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Sample records for preparations mechanical polishing

  1. Chemical mechanical polishing characteristics of ITO thin film prepared by RF magnetron sputtering

    International Nuclear Information System (INIS)

    Lee, Kang-Yeon; Choi, Gwon-Woo; Kim, Yong-Jae; Choi, Youn-Ok; Kim, Nam-Oh

    2012-01-01

    Indium-tin-oxide (ITO) thin films have attracted intensive interest because of their unique properties of good conductivity, high optical transmittance over the visible region and easy patterning ability. ITO thin films have found many applications in anti-static coatings, thermal heaters, solar cells, flat panel displays (FPDs), liquid crystal displays (LCDs), electroluminescent devices, sensors and organic light-emitting diodes (OLEDs). ITO thin films are generally fabricated by using various methods, such as spraying, chemical vapor deposition (CVD), evaporation, electron gun deposition, direct current electroplating, high frequency sputtering, and reactive sputtering. In this research, ITO films were grown on glass substrates by using a radio-frequency (RF) magnetron sputtering method. In order to achieve a high transmittance and a low resistivity, we examined the various film deposition conditions, such as substrate temperature, working pressure, annealing temperature, and deposition time. Next, in order to improve the surface quality of the ITO thin films, we performed a chemical mechanical polishing (CMP) with different process parameters and compared the electrical and the optical properties of the polished ITO thin films. The best CMP conditions with a high removal rate, low nonuniformity, low resistivity and high transmittance were as follows: platen speed, head speed, polishing time, and slurry flow rate of 30 rpm, 30 rpm, 60 sec, and 60 ml/min, respectively.

  2. Sublingual immunotherapy (SLIT – indications, mechanism, and efficacy Position paper prepared by the Section of Immunotherapy, Polish Society of Allergy

    Directory of Open Access Journals (Sweden)

    Marek Jutel

    2015-12-01

    Full Text Available SLIT ( sublingual immunotherapy induces allergen-specific immune tolerance by sublingual administration of a gradually increasing dose of an allergen. The mechanism of SLIT is comparable to those during SCIT (subcutaneous immunotherapy, with the exception of local oral dendritic cells, pre-programmed to elicit tolerance. In the SLIT dose, to achieve the same efficacy as in SCIT, it should be 50–100 times higher with better safety profile. The highest quality evidence supporting the efficacy of SLIT lasting 1 – 3 years has been provided by the large scale double-blind, placebo-controlled (DBPC trials for grass pollen extracts, both in children and adults with allergic rhinitis. Current indications for SLIT are allergic rhinitis (and conjunctivitis in both children and adults sensitized to pollen allergens (trees, grass, Parietaria , house dust mites ( Dermatophagoides pteronyssinus, Dermatophagoides farinae , cat fur, as well as mild to moderate controlled atopic asthma in children sensitized to house dust mites. There are positive findings for both asthma and new sensitization prevention. Severe adverse events, including anaphylaxis, are very rare, and no fatalities have been reported. Local adverse reactions develop in up to 70 – 80% of patients. Risk factors for SLIT adverse events have not been clearly identified. Risk factors of non-adherence to treatment might be dependent on the patient, disease treatment, physician-patient relationship, and variables in the health care system organization.

  3. Material removal mechanisms in electrochemical-mechanical polishing of tantalum

    International Nuclear Information System (INIS)

    Gao, F.; Liang, H.

    2009-01-01

    Material removal mechanisms in tantalum chemical-mechanical polishing (CMP) and electrochemical-mechanical polishing (ECMP) were investigated using the single frequency electrochemical impedance spectroscopy (EIS). Through measuring the impedance of the tantalum surface, the single frequency EIS scan made it possible to observe the CMP and ECMP processes in situ. The impedance results presented competing mechanisms of removal and formation of a surface oxide layer of tantalum. Analysis indicated that the thickness of the oxide layer formed during polishing was related to the mechanical power correlated to the friction force and the rotating speed. Furthermore, the rate of growth and removal of the oxide film was a function of the mechanical power. This understanding is beneficial for optimization of CMP and ECMP processes.

  4. Chemical Mechanical Polishing Optimization for 4H-SiC

    National Research Council Canada - National Science Library

    Neslen, Craig

    2000-01-01

    .... Preliminary chemical mechanical polishing (CMP) studies of 1 3/8" 4H-SiC wafers were performed in an attempt to identify the polishing parameter values that result in a maximum material removal rate and thus reduce substrate polishing time...

  5. Chemical mechanical glass polishing with cerium oxide: Effect of selected physico-chemical characteristics on polishing efficiency

    Czech Academy of Sciences Publication Activity Database

    Janoš, P.; Ederer, J.; Pilařová, V.; Henych, Jiří; Tolasz, Jakub; Milde, D.; Opletal, T.

    2016-01-01

    Roč. 362, SEP (2016), s. 114-120 ISSN 0043-1648 R&D Projects: GA MŠk(CZ) LM2015073 Institutional support: RVO:61388980 Keywords : Chemical mechanical polishing * Ceria-based polishing powders * Polishing efficienc Subject RIV: CA - Inorganic Chemistry Impact factor: 2.531, year: 2016

  6. Preparation of cerium oxide for lens polishing powder

    International Nuclear Information System (INIS)

    Injarean, Uthaiwan; Rodthongkom, Chouvana; Pichestapong, Pipat; Changkrurng, Kalaya

    2003-10-01

    Cerium is an element of rare earth group which is called lanthanide series. It is found in the ores like monazite and xenotime which are the tailings of tin mines in the south of Thailand. Cerium is used mostly as lens polishing powder besides the applications in other industries. In this study, cerium extracted from monazite ore breakdown by alkaline process was used for the preparation of lens polishing powder. Cerium hydroxide cake from the process was dissolved by hydrochloric acid and precipitated with oxalic acid. The oxalate precipitate then was calcined to oxide powder and its particle size was measured. Precipitation conditions being studied are concentration of feed cerium chloride solution, concentration of oxalic acid used for the precipitation, concentration of sulfuric acid used as precipitation control reagent and the precipitation temperature. It was found that the appropriate precipitation conditions yielded the fine oxide powder with particle size about 12μm. The oxide powder can be ground to the size of 1-3 μm which is suitable for making lens polishing powder

  7. Microscopic machining mechanism of polishing based on vibrations of liquid

    International Nuclear Information System (INIS)

    Huang, Z G; Guo, Z N; Chen, X; Yu, Z Q; Yu, T M; Lee, W B

    2007-01-01

    A molecular dynamics method has been applied to study the mechanism of polishing based on vibrations of liquid. Movements of polishing particles and formations of impact dents are simulated and discussed. The abrasive effect between particle and machined substrate is evaluated empirically. Polishing qualities, including roughness and fractal character under multiple impacts, are obtained by numerical methods. Results show that the particle will vibrate and roll viscously on the substrate. Press, tear and self-organization effects will be responsible for the formation of impact dents. Simulation results are compared with experimental data to verify the conclusions

  8. Study of Profile Changes during Mechanical Polishing using Relocation Profilometry

    Science.gov (United States)

    Kumaran, S. Chidambara; Shunmugam, M. S.

    2017-10-01

    Mechanical polishing is a finishing process practiced conventionally to enhance quality of surface. Surface finish is improved by mechanical cutting action of abrasive particles on work surface. Polishing is complex in nature and research efforts have been focused on understanding the polishing mechanism. Study of changes in profile is a useful method of understanding behavior of the polishing process. Such a study requires tracing same profile at regular process intervals, which is a tedious job. An innovative relocation technique is followed in the present work to study profile changes during mechanical polishing of austenitic stainless steel specimen. Using special locating fixture, micro-indentation mark and cross-correlation technique, the same profile is traced at certain process intervals. Comparison of different parameters of profiles shows the manner in which metal removal takes place in the polishing process. Mass removal during process estimated by the same relocation technique is checked with that obtained using weight measurement. The proposed approach can be extended to other micro/nano finishing processes and favorable process conditions can be identified.

  9. Optimized pre-thinning procedures of ion-beam thinning for TEM sample preparation by magnetorheological polishing.

    Science.gov (United States)

    Luo, Hu; Yin, Shaohui; Zhang, Guanhua; Liu, Chunhui; Tang, Qingchun; Guo, Meijian

    2017-10-01

    Ion-beam-thinning is a well-established sample preparation technique for transmission electron microscopy (TEM), but tedious procedures and labor consuming pre-thinning could seriously reduce its efficiency. In this work, we present a simple pre-thinning technique by using magnetorheological (MR) polishing to replace manual lapping and dimpling, and demonstrate the successful preparation of electron-transparent single crystal silicon samples after MR polishing and single-sided ion milling. Dimples pre-thinned to less than 30 microns and with little mechanical surface damage were repeatedly produced under optimized MR polishing conditions. Samples pre-thinned by both MR polishing and traditional technique were ion-beam thinned from the rear side until perforation, and then observed by optical microscopy and TEM. The results show that the specimen pre-thinned by MR technique was free from dimpling related defects, which were still residual in sample pre-thinned by conventional technique. Nice high-resolution TEM images could be acquired after MR polishing and one side ion-thinning. MR polishing promises to be an adaptable and efficient method for pre-thinning in preparation of TEM specimens, especially for brittle ceramics. Copyright © 2017 Elsevier B.V. All rights reserved.

  10. Study on chemical mechanical polishing of silicon wafer with megasonic vibration assisted.

    Science.gov (United States)

    Zhai, Ke; He, Qing; Li, Liang; Ren, Yi

    2017-09-01

    Chemical mechanical polishing (CMP) is the primary method to realize the global planarization of silicon wafer. In order to improve this process, a novel method which combined megasonic vibration to assist chemical mechanical polishing (MA-CMP) is developed in this paper. A matching layer structure of polishing head was calculated and designed. Silicon wafers are polished by megasonic assisted chemical mechanical polishing and traditional chemical mechanical polishing respectively, both coarse polishing and precision polishing experiments were carried out. With the use of megasonic vibration, the surface roughness values Ra reduced from 22.260nm to 17.835nm in coarse polishing, and the material removal rate increased by approximately 15-25% for megasonic assisted chemical mechanical polishing relative to traditional chemical mechanical polishing. Average Surface roughness values Ra reduced from 0.509nm to 0.387nm in precision polishing. The results show that megasonic assisted chemical mechanical polishing is a feasible method to improve polishing efficiency and surface quality. The material removal and finishing mechanisms of megasonic vibration assisted polishing are investigated too. Copyright © 2017 Elsevier B.V. All rights reserved.

  11. Mechanistic, kinetic, and processing aspects of tungsten chemical mechanical polishing

    Science.gov (United States)

    Stein, David

    This dissertation presents an investigation into tungsten chemical mechanical polishing (CMP). CMP is the industrially predominant unit operation that removes excess tungsten after non-selective chemical vapor deposition (CVD) during sub-micron integrated circuit (IC) manufacture. This work explores the CMP process from process engineering and fundamental mechanistic perspectives. The process engineering study optimized an existing CMP process to address issues of polish pad and wafer carrier life. Polish rates, post-CMP metrology of patterned wafers, electrical test data, and synergy with a thermal endpoint technique were used to determine the optimal process. The oxidation rate of tungsten during CMP is significantly lower than the removal rate under identical conditions. Tungsten polished without inhibition during cathodic potentiostatic control. Hertzian indenter model calculations preclude colloids of the size used in tungsten CMP slurries from indenting the tungsten surface. AFM surface topography maps and TEM images of post-CMP tungsten do not show evidence of plow marks or intergranular fracture. Polish rate is dependent on potassium iodate concentration; process temperature is not. The colloid species significantly affects the polish rate and process temperature. Process temperature is not a predictor of polish rate. A process energy balance indicates that the process temperature is predominantly due to shaft work, and that any heat of reaction evolved during the CMP process is negligible. Friction and adhesion between alumina and tungsten were studied using modified AFM techniques. Friction was constant with potassium iodate concentration, but varied with applied pressure. This corroborates the results from the energy balance. Adhesion between the alumina and the tungsten was proportional to the potassium iodate concentration. A heuristic mechanism, which captures the relationship between polish rate, pressure, velocity, and slurry chemistry, is presented

  12. Development of clean chemical mechanical polishing systems; Clean CMP system

    Energy Technology Data Exchange (ETDEWEB)

    Tsujimura, M.; Hosokawa, M. [Ebara Corp., Tokyo (Japan)

    1998-10-20

    Described herein are clean chemical mechanical polishing (CMP) systems developed by Ebara. A CMP system needs advanced peripheral techniques, in addition to those for grinding adopted by the conventional system, in order to fully exhibit its inherent functions. An integrated design concept is essential for the CMP steps, including slurry supplying, polishing, washing, process controlling and waste fluid treatment. The Ebara has adopted a standard concept `Clean CMP, dry-in and dry-out of wafers,` and provided world`s highest grades of techniques for inter-layer insulating film, shallow trench isolation, plug and wiring. The head for the polishing module is specially designed by FEM, to improve homogeneity of wafers from the center to edges. The dresser is also specially designed, to improve pad surface topolody after dressing. A slurry dipsersing method is developed to reduce slurry consumption. Various washing modules, designed to have the same external shape, can be allocated to various functions. 10 figs.

  13. Chemical Mechanical Polishing of Ruthenium, Cobalt, and Black Diamond Films

    Science.gov (United States)

    Peethala, Brown Cornelius

    Ta/TaN bilayer serves as the diffusion barrier as well as the adhesion promoter between Cu and the dielectric in 32 nm technology devices. A key concern of future technology devices (layer (vs. a bilayer of Ta/TaN) to act as a barrier. During patterning, they need to be planarized using conventional chemical mechanical polishing (CMP) to achieve a planar surface. However, CMP of these new barrier materials requires novel slurry compositions that provide adequate selectivity towards Cu and dielectric films, and minimize galvanic corrosion. Apart from the application as a barrier, Ru also has been proposed as a lower electrode material in metal-insulator-metal capacitors where high (> 50 nm/min) Ru removal rates (RRs) are required and as a stop layer in magnetic recording head fabrication where low (hydroxide (KOH). It was also determined that increased the ionic strength is not responsible for the observed increase in Ru removal rate. Benzotirazole (BTA) and ascorbic acid were added to the slurry to reduce the open circuit potential (Eoc) difference between Cu and Ru to ˜20 mV from about 550 mV in the absence of additives. A removal mechanism with KIO4 as the oxidizing agent is proposed based on the formation of several ruthenium oxides, some of which formed residues on the polishing pad below a pH of ˜7. Next, a colloidal silica-based slurry with hydrogen peroxide (H 2O2) as the oxidizer (1 wt%), and arginine (0.5 wt%) as the complexing agent was developed to polish Co at pH 10. The Eoc between Cu and Co at the above conditions was reduced to ˜20 mV compared to ˜250 mV in the absence of additives, suggestive of reduced galvanic corrosion during the Co polishing. The slurry also has the advantages of good post-polish surface quality at pH 10, and no dissolution rate. BTA at a concentration of 5mM in this slurry inhibited Cu dissolution rates and yielded a Cu/Co RR ratio of ˜0.8:1 while the open potential difference between Cu and Co was further reduced to ˜10

  14. Novel ceria-polymer microcomposites for chemical mechanical polishing

    International Nuclear Information System (INIS)

    Coutinho, Cecil A.; Mudhivarthi, Subrahmanya R.; Kumar, Ashok; Gupta, Vinay K.

    2008-01-01

    Abrasive particles are key components in slurries for chemical mechanical polishing (CMP). Since the particle characteristics determine surface quality of wafers during polishing, in this research, novel abrasive composite particles have been developed. These composite particles contain nanoparticles of ceria dispersed within cross-linked, polymeric microspheres such that the average mass fraction of ceria is approximately 50% in the particles. The microspheres are formed by co-polymerization of N-isopropylacrylamide (NIPAM) with 3-(trimethoxysilyl)propyl methacrylate (MPS) and contain interpenetrating (IP) chains of poly(acrylic acid) (PAAc). Infrared spectroscopy, dynamic light scattering, and transmission electron microscopy are employed to characterize the composite particles. Planarization of silicon dioxide wafers is studied on a bench-top CMP tester and the polished surfaces are characterized by ellipsometry, atomic force and optical microscopy. Slurries formed from the composite ceria-polymer particles lead to lower topographical variations and surface roughness than slurries of only ceria nanoparticles even though both slurries achieve similar removal rates of ∼100 nm/min for similar ceria content. Polishing with the novel composite particles gives surfaces devoid of scratches and particle deposition, which makes these particles suitable for the next generation slurries in CMP

  15. Novel ceria-polymer microcomposites for chemical mechanical polishing

    Energy Technology Data Exchange (ETDEWEB)

    Coutinho, Cecil A. [Department of Chemical and Biomedical Engineering, University of South Florida (United States); Mudhivarthi, Subrahmanya R.; Kumar, Ashok [Nanomaterials and Nanomanufacturing Research Center, University of South Florida (United States); Department of Mechanical Engineering, University of South Florida (United States); Gupta, Vinay K. [Department of Chemical and Biomedical Engineering, University of South Florida (United States)], E-mail: vkgupta@eng.usf.edu

    2008-12-30

    Abrasive particles are key components in slurries for chemical mechanical polishing (CMP). Since the particle characteristics determine surface quality of wafers during polishing, in this research, novel abrasive composite particles have been developed. These composite particles contain nanoparticles of ceria dispersed within cross-linked, polymeric microspheres such that the average mass fraction of ceria is approximately 50% in the particles. The microspheres are formed by co-polymerization of N-isopropylacrylamide (NIPAM) with 3-(trimethoxysilyl)propyl methacrylate (MPS) and contain interpenetrating (IP) chains of poly(acrylic acid) (PAAc). Infrared spectroscopy, dynamic light scattering, and transmission electron microscopy are employed to characterize the composite particles. Planarization of silicon dioxide wafers is studied on a bench-top CMP tester and the polished surfaces are characterized by ellipsometry, atomic force and optical microscopy. Slurries formed from the composite ceria-polymer particles lead to lower topographical variations and surface roughness than slurries of only ceria nanoparticles even though both slurries achieve similar removal rates of {approx}100 nm/min for similar ceria content. Polishing with the novel composite particles gives surfaces devoid of scratches and particle deposition, which makes these particles suitable for the next generation slurries in CMP.

  16. Tribochemical interaction between nanoparticles and surfaces of selective layer during chemical mechanical polishing

    International Nuclear Information System (INIS)

    Ilie, Filip

    2013-01-01

    Nanoparticles have been widely used in polish slurries such as those in the chemical mechanical polishing (CMP) process. For understanding the mechanisms of CMP, an atomic force microscope (AFM) is used to characterize polished surfaces of selective layers, after a set of polishing experiments. To optimize the CMP polishing process, one needs to get information on the interaction between the nano-abrasive slurry nanoparticles and the surface of selective layer being polished. The slurry used in CMP process of the solid surfaces is slurry with large nanoparticle size colloidal silica sol nano-abrasives. Silica sol nano-abrasives with large nanoparticle are prepared and characterized by transmission electron microscopy, particles colloidal size, and Zeta potential in this paper. The movement of nanoparticles in liquid and the interaction between nanoparticles and solid surfaces coating with selective layer are very important to obtain an atomic alloy smooth surface in the CMP process. We investigate the nanoparticle adhesion and removal processes during CMP and post-CMP cleaning. The mechanical interaction between nanoparticles and the wafer surface was studied using a microcontact wear model. This model considers the nanoparticle effects between the polishing interfaces during load balancing. Experimental results on polishing and cleaning are compared with numerical analysis. This paper suggests that during post-CMP cleaning, a combined effort in chemical and mechanical interaction (tribochemical interactions) would be effective in removal of small nanoparticles during cleaning. For large nanoparticles, more mechanical forces would be more effective. CMP results show that the removal rate has been improved to 367 nm/min and root mean square (RMS) of roughness has been reduced from 4.4 to 0.80 nm. Also, the results show that the silica sol nano-abrasives about 100 nm are of higher stability (Zeta potential is −65 mV) and narrow distribution of nanoparticle

  17. Surface qualities after chemical-mechanical polishing on thin films

    International Nuclear Information System (INIS)

    Fu, Wei-En; Lin, Tzeng-Yow; Chen, Meng-Ke; Chen, Chao-Chang A.

    2009-01-01

    Demands for substrate and film surface planarizations significantly increase as the feature sizes of Integrated Circuit (IC) components continue to shrink. Chemical Mechanical Polishing (CMP), incorporating chemical and mechanical interactions to planarize chemically modified surface layers, has been one of the major manufacturing processes to provide global and local surface planarizations in IC fabrications. Not only is the material removal rate a concern, the qualities of the CMP produced surface are critical as well, such as surface finish, defects and surface stresses. This paper is to examine the CMP produced surface roughness on tungsten or W thin films based on the CMP process conditions. The W thin films with thickness below 1000 nm on silicon wafer were chemical-mechanical polished at different down pressures and platen speeds to produce different surface roughness. The surface roughness measurements were performed by an atomic force microscope (DI D3100). Results show that the quality of surface finish (R a value) is determined by the combined effects of down pressures and platen speeds. An optimal polishing condition is, then, possible for selecting the down pressures and platen speeds.

  18. Antioxidative properties of milk protein preparations fermented by Polish strains of Lactobacillus helveticus.

    Science.gov (United States)

    Skrzypczak, Katarzyna W; Gustaw, Waldemar Z; Jabłońska-Ryś, Ewa D; Michalak-Majewska, Monika; Sławińska, Aneta; Radzki, Wojciech P; Gustaw, Klaudia M; Waśko, Adam D

    2017-01-01

    The increasing significance of food products containing substances with antioxidative activi- ties is currently being observed. This is mainly due to the fact that pathogenic changes underlying some diseases are related to the carcinogenic effects of free radicals. Antioxidative compounds play an important role in supporting and enhancing the body’s defense mechanisms, which is useful in preventing some civili- zation diseases. Unfortunately, it has been already proved that some synthetic antioxidants pose a potential risk in vivo. Therefore, antioxidant compounds derived from a natural source are extremely valuable. Milk is a source of biologically active precursors, which when enclosed in structural protein sequences are inactive. The hydrolysis process, involving bacterial proteolytic enzymes, might release biopeptides that act in various ways, including having antioxidant properties. The objective of this study was to determine the antioxidant properties of milk protein preparations fermented by Polish strains of L. helveticus. The research also focused on evaluating the dynamics of milk acidification by these strains and analyzing the textural properties of the skim milk fermented products obtained. The research studied Polish strains of L. helveticus: B734, 141, T80 and T105, which have not yet been used industrially. The antioxidant properties of 1% (w/v) solutions of milk protein preparations (skim milk powder, caseinoglycomacropeptide and α-lactoalbumin) fermented by these strains were determined by neutralizing the free radicals with 2,2-diphenyl-1-picrylhydrazyl (DPPH˙). Moreover, solutions of skim milk powder (SMP) fermented by the microorganisms being tested were analyzed on gel electrophoresis (SDS-PAGE). The dynamics of milk acidification by these microorganisms was also analyzed L. helveticus strains were used to prepare fermented regenerated skim milk products that were subjected to texture profile analysis (TPA) performed using a TA-XT2i

  19. A novel vibration assisted polishing device based on the flexural mechanism driven by the piezoelectric actuators

    Directory of Open Access Journals (Sweden)

    Guilian Wang

    2018-01-01

    Full Text Available The vibration assisted polishing has widely application fields because of higher machining frequency and better polishing quality, especially the polishing with the non-resonant mode that is regarded as a kind of promising polishing method. This paper reports a novel vibration assisted polishing device, consisting of the flexible hinge mechanism driven by the piezoelectric actuators, which is suitable for polishing planes or curve surfaces with slow curvature. Firstly, the generation methods of vibration trajectory are investigated for the same frequency and different frequency signals’ inputs, respectively, and then the types of elliptic and Lissajous’s vibration trajectories are generated respectively. Secondly, a flexural mechanism consisting of the right circular flexible hinges and the leaf springs is developed to produce two-dimensional vibration trajectory. Statics and dynamics investigating of this flexible mechanism are finished in detail. The analytical models about input and output compliances of the flexural mechanism are established according to the matrix-based compliance modeling, and the dynamic model of the flexural mechanism based on the Euler-Lagrange equation is also presented. The finite element model of the flexural mechanism was established to carry out the numerical simulation in order to testify the rationality of device design. Finally, the polishing experiment is carried out to prove the effectiveness of the vibration device. The experimental results show that this novel vibration assisted polishing device developed in this study can remove more effectively the cutting marks left by last process and obviously reduce the workpiece surface roughness.

  20. KDP Aqueous Solution-in-Oil Microemulsion for Ultra-Precision Chemical-Mechanical Polishing of KDP Crystal

    Directory of Open Access Journals (Sweden)

    Hui Dong

    2017-03-01

    Full Text Available A novel functional KH2PO4 (KDP aqueous solution-in-oil (KDP aq/O microemulsion system for KDP crystal ultra-precision chemical-mechanical polishing (CMP was prepared. The system, which consisted of decanol, Triton X-100, and KH2PO4 aqueous solution, was available at room temperature. The functional KDP aq/O microemulsion system was systematically studied and applied as polishing solution to KDP CMP technology. In this study, a controlled deliquescent mechanism was proposed for KDP polishing with the KDP aq/O microemulsion. KDP aqueous solution, the chemical etchant in the polishing process, was caged into the micelles in the microemulsion, leading to a limitation of the reaction between the KDP crystal and KDP aqueous solution only if the microemulsion was deformed under the effect of the external force. Based on the interface reaction dynamics, KDP aqueous solutions with different concentrations (cKDP were applied to replace water in the traditional water-in-oil (W/O microemulsion. The practicability of the controlled deliquescent mechanism was proved by the decreasing material removal rate (MRR with the increasing of the cKDP. As a result, the corrosion pits on the KDP surface were avoided to some degree. Moreover, the roughnesses of KDP with KDP aq/O microemulsion (cKDP was changed from 10 mM to 100 mM as polishing solutions were smaller than that with the W/O microemulsion. The smallest surface root-mean-square roughness of 1.5 nm was obtained at a 30 mmol/L KDP aq solution, because of the most appropriate deliquescent rate and MRR.

  1. Chemical mechanical polishing of hard disk substrate with {alpha}-alumina-g-polystyrene sulfonic acid composite abrasive

    Energy Technology Data Exchange (ETDEWEB)

    Lei Hong, E-mail: hong_lei2005@yahoo.com.c [Research Center of Nano-science and Nano-technology, Shanghai University, Shanghai 200444 (China); Bu Naijing; Chen Ruling; Hao Ping [Research Center of Nano-science and Nano-technology, Shanghai University, Shanghai 200444 (China); Neng Sima; Tu Xifu; Yuen Kwok [Shenzhen Kaifa Magnetic Recording Co., LTD, Shenzhen, 518035 (China)

    2010-05-03

    {alpha}-Alumina-g-polystyrene sulfonic acid ({alpha}-Al{sub 2}O{sub 3}-g-PSS) composite abrasive was prepared by surface activation, graft polymerization and sulfonation, successively. The composition, dispersibility and morphology of the product were characterized by Fourier transformed infrared spectroscopy, laser particle size analysis and scanning electron microscopy, respectively. The chemical mechanical polishing (CMP) performances of the composite abrasive on hard disk substrate with nickel-phosphorous plating were investigated. The microscopy images of the polished surfaces show that {alpha}-Al{sub 2}O{sub 3}-g-PSS composite abrasive results in improved CMP and post-CMP cleaning performances than pure {alpha}-alumina abrasive under the same testing conditions.

  2. Models of nanoparticles movement, collision, and friction in chemical mechanical polishing (CMP)

    Energy Technology Data Exchange (ETDEWEB)

    Ilie, Filip, E-mail: filip@meca.omtr.pub.ro [Polytechnic University of Bucharest, Department of Machine Elements and Tribology (Romania)

    2012-03-15

    Nanoparticles have been widely used in polishing slurry such as chemical mechanical polishing (CMP) process. The movement of nanoparticles in polishing slurry and the interaction between nanoparticles and solid surface are very important to obtain an atomic smooth surface in CMP process. Polishing slurry contains abrasive nanoparticles (with the size range of about 10-100 nm) and chemical reagents. Abrasive nanoparticles and hydrodynamic pressure are considered to cause the polishing effect. Nanoparticles behavior in the slurry with power-law viscosity shows great effect on the wafer surface in polishing process. CMP is now a standard process of integrated circuit manufacturing at nanoscale. Various models can dynamically predict the evolution of surface topography for any time point during CMP. To research, using a combination of individual nanoscale friction measurements for CMP of SiO{sub 2}, in an analytical model, to sum these effects, and the results scale CMP experiments, can guide the research and validate the model. CMP endpoint measurements, such as those from motor current traces, enable verification of model predictions, relating to friction and wear in CMP and surface topography evolution for different types of CMP processes and patterned chips. In this article, we explore models of the microscopic frictional force based on the surface topography and present both experimental and theoretical studies on the movement of nanoparticles in polishing slurry and collision between nanoparticles, as well as between the particles and solid surfaces in time of process CMP. Experimental results have proved that the nanoparticle size and slurry properties have great effects on the polishing results. The effects of the nanoparticle size and the slurry film thickness are also discussed.

  3. Combined Ultrasonic Elliptical Vibration and Chemical Mechanical Polishing of Monocrystalline Silicon

    Directory of Open Access Journals (Sweden)

    Liu Defu

    2016-01-01

    Full Text Available An ultrasonic elliptical vibration assisted chemical mechanical polishing(UEV-CMP is employed to achieve high material removal rate and high surface quality in the finishing of hard and brittle materials such as monocrystalline silicon, which combines the functions of conventional CMP and ultrasonic machining. In theultrasonic elliptical vibration aided chemical mechanical polishingexperimental setup developed by ourselves, the workpiece attached at the end of horn can vibrate simultaneously in both horizontal and vertical directions. Polishing experiments are carried out involving monocrystalline silicon to confirm the performance of the proposed UEV-CMP. The experimental results reveal that the ultrasonic elliptical vibration can increase significantly the material removal rate and reduce dramatically the surface roughness of monocrystalline silicon. It is found that the removal rate of monocrystalline silicon polished by UEV-CMP is increased by approximately 110% relative to that of conventional CMP because a passive layer on the monocrystalline silicon surface, formed by the chemical action of the polishing slurry, will be removed not only by the mechanical action of CMP but also by ultrasonic vibration action. It indicates that the high efficiency and high quality CMP of monocrystalline silicon can be performed with the proposed UEV-CMP technique.

  4. Mechanical polishing as an improved surface treatment for platinum screen-printed electrodes

    Directory of Open Access Journals (Sweden)

    Junqiao Lee

    2016-07-01

    Full Text Available The viability of mechanical polishing as a surface pre-treatment method for commercially available platinum screen-printed electrodes (SPEs was investigated and compared to a range of other pre-treatment methods (UV-Ozone treatment, soaking in N,N-dimethylformamide, soaking and anodizing in aqueous NaOH solution, and ultrasonication in tetrahydrofuran. Conventional electrochemical activation of platinum SPEs in 0.5 M H2SO4 solution was ineffective for the removal of contaminants found to be passivating the screen-printed surfaces. However, mechanical polishing showed a significant improvement in hydrogen adsorption and in electrochemically active surface areas (probed by two different redox couples due to the effective removal of surface contaminants. Results are also presented that suggest that SPEs are highly susceptible to degradation by strong acidic or caustic solutions, and could potentially lead to instability in long-term applications due to continual etching of the binding materials. The ability of SPEs to be polished effectively extends the reusability of these traditionally “single-use” devices. Keywords: Screen-printed electrodes, Polishing, Platinum, Activation, Pre-treatment, Cyclic voltammetry

  5. Preparation and preliminary of two new Polish CRMs for inorganic trace analysis

    International Nuclear Information System (INIS)

    Dybczynski, R.; Danko, B.; Kulisa, K.; Maleszewska, E.; Polkowska-Motrenko, H.; Samczynski, Z.; Szopa, Z.

    2004-01-01

    Preparation and characterization of two new reference materials of biological origin, namely: Tea Leaves (INCT-TL-1) and Mixed Polish Herbs (INCT-MPH-2) is described. The raw materials were ground in an agate ball mill, sieved through a nylon sieve, collecting fraction of particle size: diameter ≤67 μm, and carefully homogenized. Preliminary homogeneity testing by XRF method and final checking of homogeneity by NAA after distribution of the materials into containers revealed that they are sufficiently homogeneous at least for sample size ≥100 mg. Both materials were prepared in amounts exceeding 40 kg and certified on the basis of a worldwide interlaboratory comparison, in which 109 laboratories from 19 countries participated. The method of data evaluation leading to assignment of certified values was essentially the same as that used previously in this Laboratory, but supplemented by additional data from the analysis of a CRM which was sent to the participants and analyzed by them along with the candidate reference materials. In addition the results for a few elements by very accurate developed methods in this Laboratory were obtained and used to support the certification process. Analytical uncertainties and stability uncertainties were quantified to arrive at combined uncertainties of the certified values. So far 18 elements in INCT-TL-1 and 21 in INCT-MPH-2 could be certified. (author)

  6. Microscopic investigations of chemo-mechanical polishing of tungsten

    International Nuclear Information System (INIS)

    Lim, Min Soo; Heide, Paul A.W. van der; Perry, Scott S.; Galloway, Heather C.; Koeck, Deborah C.

    2004-01-01

    The influence of aqueous solutions of KNO 3 , KClO 3 , and KIO 3 on tungsten surfaces has been investigated in terms of the degree of surface oxidation, metal dissolution and interfacial friction. The surface properties of tungsten films have been measured ex-situ with X-ray photoelectron spectroscopy and in situ with atomic force microscopy. Measurements of the surface composition reveal a greater degree of oxidation for surfaces treated in solutions of KIO 3 in comparison to the other solutions. This increase in surface oxidation is correlated to a greater rate of localized film dissolution that occurs under the action of the scanning probe tip. In turn, the process of material removal is the predominant origin of the higher interfacial friction measured at tungsten surfaces immersed in KIO 3 solutions, as compared to KClO 3 and KNO 3 solutions. Collectively, these measurements portray a fundamental pathway of material removal at tungsten surfaces in the presence of oxidizing species and highlight complementary roles of chemical and mechanical action

  7. Microscopic investigations of chemo-mechanical polishing of tungsten

    Energy Technology Data Exchange (ETDEWEB)

    Lim, Min Soo; Heide, Paul A.W. van der; Perry, Scott S.; Galloway, Heather C.; Koeck, Deborah C

    2004-06-15

    The influence of aqueous solutions of KNO{sub 3}, KClO{sub 3}, and KIO{sub 3} on tungsten surfaces has been investigated in terms of the degree of surface oxidation, metal dissolution and interfacial friction. The surface properties of tungsten films have been measured ex-situ with X-ray photoelectron spectroscopy and in situ with atomic force microscopy. Measurements of the surface composition reveal a greater degree of oxidation for surfaces treated in solutions of KIO{sub 3} in comparison to the other solutions. This increase in surface oxidation is correlated to a greater rate of localized film dissolution that occurs under the action of the scanning probe tip. In turn, the process of material removal is the predominant origin of the higher interfacial friction measured at tungsten surfaces immersed in KIO{sub 3} solutions, as compared to KClO{sub 3} and KNO{sub 3} solutions. Collectively, these measurements portray a fundamental pathway of material removal at tungsten surfaces in the presence of oxidizing species and highlight complementary roles of chemical and mechanical action.

  8. Chemical-mechanical polishing of metal and dielectric films for microelectronic applications

    Science.gov (United States)

    Hegde, Sharath

    The demand for smaller, faster devices has led the integrated circuit (IC) industry to continually increase the device density on a chip while simultaneously reducing feature dimensions. Copper interconnects and multilevel metallization (MLM) schemes were introduced to meet some of these challenges. With the employment of MLM in the ultra-large-scale-integrated (ULSI) circuit fabrication technology, repeated planarization of different surface layers with tolerance of a few nanometers is required. Presently, chemical-mechanical planarization (CMP) is the only technique that can meet this requirement. Damascene and shallow trench isolation processes are currently used in conjunction with CMP in the fabrication of multilevel copper interconnects and isolation of devices, respectively, for advanced logic and memory devices. These processes, at some stage, require simultaneous polishing of two different materials using a single slurry that offers high polish rates, high polish selectivity to one material over the other and good post-polish surface finish. Slurries containing one kind of abrasive particles do not meet most of these demands due mainly to the unique physical and chemical properties of each abrasive. However, if a composite particle is formed that takes the advantages of different abrasives while mitigating their disadvantages, the CMP performance of resulting abrasives would be compelling. It is demonstrated that electrostatic interactions between ceria and silica particles at pH 4 can be used to produce composite particles with enhanced functionality. Zeta potential measurement and TEM images used for particle characterization show the presence of such composite particles with smaller shell particles attached onto larger core particles. Slurries containing ceria (core)/silica (shell) and silica (core)/ceria (shell) composite particles when used to polish metal and dielectric films, respectively, yield both enhanced metal and dielectric film removal rates

  9. Mirror-smooth surfaces and repair of defects in superconducting RF cavities by mechanical polishing

    Energy Technology Data Exchange (ETDEWEB)

    Cooper, C. A. [Fermilab; Cooley, L. D. [Fermilab

    2012-11-22

    Mechanical techniques for polishing the inside surface of niobium superconducting radio-frequency (SRF) cavities have been systematically explored. By extending known techniques to fine polishing, mirror-like finishes were produced, with <15 nm RMS (root mean square) roughness over 1 mm2 scan area. This is an order of magnitude less than the typical roughness produced by the electropolishing of niobium cavities. The extended mechanical polishing (XMP) process was applied to several SRF cavities which exhibited equator defects that caused quench at <20 MV m-1 and were not improved by further electropolishing. Cavity optical inspection equipment verified the complete removal of these defects, and minor acid processing, which dulled the mirror finish, restored performance of the defective cells to the high gradients and quality factors measured for adjacent cells when tested with other harmonics. This innate repair feature of XMP could be used to increase manufacturing yield. Excellent superconducting properties resulted after initial process optimization, with quality factor Q of 3 × 1010 and accelerating gradient of 43 MV m-1 being attained for a single-cell TESLA cavity, which are both close to practical limits. Several repaired nine-cell cavities also attained Q > 8 × 109 at 35 MV m-1, which is the specification for the International Linear Collider. Future optimization of the process and pathways for eliminating requirements for acid processing are also discussed.

  10. Evaluation of environmental impacts during chemical mechanical polishing (CMP) for sustainable manufacturing

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Hyun Seop; Park, Sun Joon; Jeong, Hae Do [Pusan National University, Busan (Korea, Republic of)

    2013-02-15

    Reducing energy consumption has become a critical issue in manufacturing. The semiconductor industry in particular is confronted with environmental regulations on pollution associated with electric energy, chemical, and ultrapure water (UPW) consumptions. This paper presents the results of an evaluation of the environmental impacts during chemical mechanical polishing (CMP), a key process for planarization of dielectrics and metal films in ultra-large-scale integrated circuits. The steps in the CMP process are idling, conditioning, wetting, wafer loading/unloading, head dropping, polishing, and rinsing. The electric energy, CMP slurry, and UPW consumptions associated with the process and their impacts on global warming are evaluated from an environmental standpoint. The estimates of electric energy, slurry, and UPW consumptions as well as the associated greenhouse gas emissions presented in this paper will provide a technical aid for reducing the environmental burden associated with electricity consumption during the CMP process.

  11. Role of crystal orientation on chemical mechanical polishing of single crystal copper

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, Aibin, E-mail: abzhu@mail.xjtu.edu.cn; He, Dayong; Luo, Wencheng; Liu, Yangyang

    2016-11-15

    Highlights: • The role of crystal orientation in cooper CMP by quasi-continuum was studied. • The atom displacement diagrams were obtained and analyzed. • The stress distribution diagrams and load-displacement curves were analyzed. • This research is helpful to revealing the material removal mechanism of CMP. - Abstract: The material removal mechanism of single crystal copper in chemical mechanical polishing (CMP) has not been intensively investigated. And the role of crystal orientation in CMP of single crystal cooper is not quite clear yet. Quasi-continuum method was adopted in this paper to simulate the process of nano-particles grinding on single crystal copper in CMP process. Three different crystal orientations, i.e. x[100]y[001], x[001]y[110] and x[–211]y[111], were chosen for analysis. The atom displacement diagrams, stress distribution diagrams and load-displacement curves were obtained. After analyzing the deformation mechanism, residual stress of the work piece material and cutting force, results showed that, the crystal orientation of work piece has great influence on the deformation characteristics and surface quality of work piece during polishing. In the A(001)[100] orientation, the residual stress distribution after polishing is deeper, and the stress is larger than that in the B(110)[001] and C(111)[–211] orientations. And the average tangential cutting force in the A(001)[100] orientation is much larger than those in the other two crystal orientation. This research is helpful to revealing the material removal mechanism of CMP process.

  12. Effects of catalyst concentration and ultraviolet intensity on chemical mechanical polishing of GaN

    Science.gov (United States)

    Wang, Jie; Wang, Tongqing; Pan, Guoshun; Lu, Xinchun

    2016-08-01

    Effects of catalyst concentration and ultraviolet intensity on chemical mechanical polishing (CMP) of GaN were deeply investigated in this paper. Working as an ideal homogeneous substrate material in LED industry, GaN ought to be equipped with a smooth and flat surface. Taking the strong chemical stability of GaN into account, photocatalytic oxidation technology was adopted in GaN CMP process to realize efficient removal. It was found that, because of the improved reaction rate of photocatalytic oxidation, GaN material removal rate (MRR) increases by a certain extent with catalyst concentration increasing. Cross single line analysis on the surface after polishing by Phase Shift MicroXAM-3D was carried out to prove the better removal effect with higher catalyst concentration. Ultraviolet intensity field in H2O2-SiO2-based polishing system was established and simulated, revealing the variation trend of ultraviolet intensity around the outlet of the slurry. It could be concluded that, owing to the higher planarization efficiency and lower energy damage, the UV lamp of 125 W is the most appropriate lamp in this system. Based on the analysis, defects removal model of this work was proposed to describe the effects of higher catalyst concentration and higher power of UV lamp.

  13. Design of an ultraprecision computerized numerical control chemical mechanical polishing machine and its implementation

    Science.gov (United States)

    Zhang, Chupeng; Zhao, Huiying; Zhu, Xueliang; Zhao, Shijie; Jiang, Chunye

    2018-01-01

    The chemical mechanical polishing (CMP) is a key process during the machining route of plane optics. To improve the polishing efficiency and accuracy, a CMP model and machine tool were developed. Based on the Preston equation and the axial run-out error measurement results of the m circles on the tin plate, a CMP model that could simulate the material removal at any point on the workpiece was presented. An analysis of the model indicated that lower axial run-out error led to lower material removal but better polishing efficiency and accuracy. Based on this conclusion, the CMP machine was designed, and the ultraprecision gas hydrostatic guideway and rotary table as well as the Siemens 840Dsl numerical control system were incorporated in the CMP machine. To verify the design principles of machine, a series of detection and machining experiments were conducted. The LK-G5000 laser sensor was employed for detecting the straightness error of the gas hydrostatic guideway and the axial run-out error of the gas hydrostatic rotary table. A 300-mm-diameter optic was chosen for the surface profile machining experiments performed to determine the CMP efficiency and accuracy.

  14. Fe-N{sub x}/C assisted chemical–mechanical polishing for improving the removal rate of sapphire

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Li, E-mail: xl0522@126.com [State Key Laboratory of Tribology, Tsinghua University, Beijing 100084 (China); Shenzhen Key Laboratory of Micro/Nano Manufacturing, Research Institute of Tsinghua University in Shenzhen, Shenzhen 518057 (China); Zou, Chunli; Shi, Xiaolei [State Key Laboratory of Tribology, Tsinghua University, Beijing 100084 (China); Shenzhen Key Laboratory of Micro/Nano Manufacturing, Research Institute of Tsinghua University in Shenzhen, Shenzhen 518057 (China); Pan, Guoshun, E-mail: pangs@tsinghua.edu.cn [State Key Laboratory of Tribology, Tsinghua University, Beijing 100084 (China); Shenzhen Key Laboratory of Micro/Nano Manufacturing, Research Institute of Tsinghua University in Shenzhen, Shenzhen 518057 (China); Luo, Guihai; Zhou, Yan [State Key Laboratory of Tribology, Tsinghua University, Beijing 100084 (China); Shenzhen Key Laboratory of Micro/Nano Manufacturing, Research Institute of Tsinghua University in Shenzhen, Shenzhen 518057 (China)

    2015-07-15

    Highlights: • A novel non-noble metal catalyst (Fe-N{sub x}/C) was prepared. • Fe-N{sub x}/C shows remarkable catalytic activity for improving the removal rate of sapphire in alkaline solution. • The optimum CMP removal by Fe-N{sub x}/C yielded a superior surface finish of 0.078 nm the average roughness. • Fe{sub 2}O{sub 3}, Fe{sub 3}O{sub 4}, pyridinic N as well as pyrrolic N group possibly serving as the catalytic sites. • A soft hydration layer (boehmite, AlO(OH)) was generated on the surface of sapphire during CMP process. - Abstract: In this paper, a novel non-noble metal catalyst (Fe-N{sub x}/C) is used to improve the removal mass of sapphire as well as obtain atomically smooth sapphire wafer surfaces. The results indicate that Fe-N{sub x}/C shows good catalytic activity towards sapphire removal rate. And the material removal rates (MRRs) are found to vary with the catalyst content in the polishing fluid. Especially that when the polishing slurry mixes with 16 ppm Fe-N{sub x}/C shows the maximum MRR and its removal mass of sapphire is 38.43 nm/min, more than 15.44% larger than traditional CMP using the colloidal silicon dioxide (SiO{sub 2}) without Fe-N{sub x}/C. Catalyst-assisted chemical–mechanical polishing of sapphire is studied with X-ray photoelectron spectroscopy (XPS). It is found that the formation of a soft hydration layer (boehmite, γ-AlOOH or γ-AlO(OH)) on sapphire surface facilitates the material removal and achieving fine surface finish on basal plane. Abrasives (colloid silica together with magnetite, ingredient of Fe-N{sub x}/C) with a hardness between boehmite and sapphire polish the c-plane of sapphire with good surface finish and efficient removal. Fe{sub 2}O{sub 3}, Fe{sub 3}O{sub 4}, pyridinic N as well as pyrrolic N group would be the catalytical active sites and accelerate this process. Surface quality is characterized with atomic force microscopy (AFM). The optimum CMP removal by Fe-N{sub x}/C also yields a superior

  15. Polish reference material: corn flour (INCT-CF-3)for inorganic trace analysis - preparation and certification

    International Nuclear Information System (INIS)

    Polkowska-Motrenko, H.; Dybczynski, R.; Chajduk, E.; Danko, B.; Kulisa, K.; Samczynski, Z.; Sypula, M.; Szopa, Z.

    2006-01-01

    Preparation, examination and certification of the new matrix reference material of biological origin: Corn Flour (INCT-CF-3) is described. The material was prepared from corn grown in Poland according to Polish standard PN-A-74205:1997. The material was sieved through the 250 mm nylon sieves and stored in a polyethylene (PE) bag. Approximately 50 kg of sieved corn flour was collected. Examination by optical microscopy revealed that Martin's diameter of over 98% of particles was below 25 mm. The whole lot of corn flour was then homogenized by mixing for 20 hours in a 110 dm 3 PE drum rotated in three directions. Preliminary homogeneity testing by X-ray fluorescence (XRF) method and final checking of homogeneity by neutron activation analysis (NAA) after distribution of the material into containers revealed, that it is sufficiently homogeneous at least for a sample size ≥ 100 mg. In order to assure the long-term stability, all containers with INCT-CF-3 were sterilized by electron beam radiation. Long-term stability was checked by analyzing concentrations of selected elements in the material stored in the air-conditioned room at 20 o C. Short-term stability was examined by the determination of concentrations of the selected elements in the bottle stored in the CO 2 incubator at 37 o C. The material was certified on the basis of a worldwide interlaboratory comparison, in which 92 laboratories from 19 countries participated providing 962 laboratory averages (4228 individual determinations) for 57 elements. A method of data evaluation leading to assignment of certified values was the same as that used previously in the Laboratory of the Department of Analytical Chemistry, Institute of Nuclear Chemistry and Technology. The result for Mo was obtained by definitive methods developed in the Laboratory and used to support the certification process. Analytical uncertainties and stability uncertainties were quantified to arrive at combined uncertainties of the certified

  16. Passivation of mechanically polished, chemically etched and anodized zirconium in various aqueous solutions: Impedance measurements

    International Nuclear Information System (INIS)

    Abo-Elenien, G.M.; Abdel-Salam, O.E.

    1987-01-01

    Zirconium and its alloys are finding increasing applications especially in water-cooled nuclear reactors. Because of the fact that zirconium is electronegative (E 0 = -1.529V) its corrosion resistance in aqueous solutions is largely determined by the existence of a thin oxide film on its surface. The structure and properties of this film depend in the first place on the method of surface pre-treatment. This paper presents an experimental study of the nature of the oxide film on mechanically polished, chemically etched and anodized zirconium. Ac impedance measurements carried out in various acidic, neutral and alkaline solutions show that the film thickness depends on the method of surface pre-treatment and the type of electrolyte solution. The variation of the potential and impedance during anodization of zirconium at low current density indicates that the initial stages of polarization consist of oxide build-up at a rate dependent on the nature of the electrode surface and the electrolyte. Oxygen evolution commences at a stage where oxide thickening starts to decline. The effect of frequency on the measured impedance indicates that the surface reactivity, and hence the corrosion rate, decreases in the following order: mechanically polished > chemically etched > anodized

  17. Radioactive recontamination on mechanically polished piping at Shimane-1 Nuclear Power Plant

    International Nuclear Information System (INIS)

    Umeda, K.; Komoto, I.; Imamura, K.; Kataoka, I.; Uchida, S.

    1998-01-01

    In a series of preventive maintenance tasks for an aging plant, recirculation pipes of Shimane-1 NPP have been replaced by newly fabricated type 316 NG stainless steel pipes. Suppression of shutdown dose rate caused by 60 Co recontamination on the newly replaced piping was one of the major concerns in the recirculation pipe replacement. In order to suppress the shutdown dose rate, control of the 60 Co deposition rate coefficient as well as 60 Co radioactivity in the reactor water are essential. The deposition rate coefficient depends on surface roughness. The coefficient is suppressed by reduction of the effective surface area of pipes through mechanical polishing. Then the inner surface of the pipes was polished mechanically to reduce roughness prior to application in the plant. After measuring and evaluating radioactive recontamination, it was estimated that deposited amounts of radioactive corrosion products on the pipe inner surface would reach the saturated value in a few years, and would not exceed the level before replacement unless water chemistry is degraded. (author)

  18. Effect of conditioner load on the polishing pad surface during chemical mechanical planarization process

    Energy Technology Data Exchange (ETDEWEB)

    Shin, Cheol Min; Qin, Hong Yi; Hong, Seok Jun; Jeon, Sang Hyuk; Kulkarni, Atul; Kim, Tae Sun [Sungkyunkwan University, Suwon (Korea, Republic of)

    2016-12-15

    During the Chemical mechanical planarization (CMP), the pad conditioning process can affect the pad surface characteristics. Among many CMP process parameters, the improper applied load on the conditioner arm may have adverse effects on the polyurethane pad. In this work, we evaluated the pad surface properties under the various conditioner arm applied during pad conditioning process. The conditioning pads were evaluated for surface topography, surface roughness parameters such as Rt and Rvk and Material removal rate (MRR) and within-wafer non-uniformity after wafer polishing. We observed that, the pad asperities were collapsed in the direction of conditioner rotation and blocks the pad pores applied conditioner load. The Rvk value and MRR were founded to be in relation with 4 > 1 > 7 kgF conditioner load. Hence, this study shows that, 4 kgF applied load by conditioner is most suitable for the pad conditioning during CMP.

  19. Reactive Ion Etching as Cleaning Method Post Chemical Mechanical Polishing for Phase Change Memory Device

    International Nuclear Information System (INIS)

    Min, Zhong; Zhi-Tang, Song; Bo, Liu; Song-Lin, Feng; Bomy, Chen

    2008-01-01

    In order to improve nano-scale phase change memory performance, a super-clean interface should be obtained after chemical mechanical polishing (CMP) of Ge 2 Sb 2 Te 5 phase change films. We use reactive ion etching (RIE) as the cleaning method. The cleaning effect is analysed by scanning electron microscopy and an energy dispersive spectrometer. The results show that particle residue on the surface has been removed. Meanwhile, Ge 2 Sb 2 Te 5 material stoichiometric content ratios are unchanged. After the top electrode is deposited, current-voltage characteristics test demonstrates that the set threshold voltage is reduced from 13 V to 2.7V and the threshold current from 0.1mA to 0.025mA. Furthermore, we analyse the RIE cleaning principle and compare it with the ultrasonic method

  20. Characterization of chemical interactions during chemical mechanical polishing (CMP) of copper

    Science.gov (United States)

    Lee, Seung-Mahn

    2003-10-01

    Chemical mechanical polishing (CMP) has received much attention as an unique technique to provide a wafer level planarization in semiconductor manufacturing. However, despite the extensive use of CMP, it still remains one of the least understood areas in semiconductor processing. The lack of the fundamental understanding is a significant barrier to further advancements in CMP technology. One critical aspect of metal CMP is the formation of a thin surface layer on the metal surface. The formation and removal of this layer controls all the aspects of the CMP process, including removal rate, surface finish, etc. In this dissertation, we focus on the characterization of the formation and removal of the thin surface layer on the copper surface. The formation dynamics was investigated using static and dynamic electrochemical techniques, including potentiodynamic scans and chronoamperometry. The results were validated using XPS measurements. The mechanical properties of the surface layer were investigated using nanoindentation measurements. The electrochemical investigation showed that the thickness of the surface layer is controlled by the chemicals such as an oxidizer (hydrogen peroxide), a corrosion inhibitor (benzotriazole), a complexing agent (citric acid), and their concentrations. The dynamic electrochemical measurements indicated that the initial layer formation kinetics is unaffected by the corrosion inhibitors. The passivation due to the corrosion inhibitor becomes important only on large time scales (>200 millisecond). The porosity and the density of the chemically modified surface layer can be affected by additives of other chemicals such as citric acid. An optimum density of the surface layer is required for high polishing rate while at the same time maintaining a high degree of surface finish. Nanoindentation measurements indicated that the mechanical properties of the surface layer are strongly dependent on the chemical additives in the slurry. The CMP

  1. Effect of chemical disinfectant on the transverse strength of heat-polymerized acrylic resins subjected to mechanical and chemical polishing: an in vitro study.

    Science.gov (United States)

    Sharan, Smitha; Kavitha, H R; Konde, Harish; Kalahasti, Deepthi

    2012-05-01

    To evaluate the effect of chemical disinfectant on the transverse strength of heat-polymerized acrylic resins subjected to mechanical and chemical polishing. A total of 256 rectangular specimens (65 * 10 * 3 mm) 128 per resin (Lucitone-199 and Acralyn-H) were fabricated. One side of each specimen was not polished and the other was either mechanically (n = 96) or chemically (n = 96) polished and immersed for 10, 30 and 60 minutes in 2% alkaline glutaraldehyde. Mechanically polished (n = 32) and chemically polished (n = 32) control specimens were immersed only in distilled water. The transverse strength (N/mm(2)) was tested for failure in a universal testing machine, at a crosshead speed of 5 mm/min. Data were statistically analyzed using 2-way ANOVA and Student t-test. chemical polishing resulted in significantly lower transverse strength values than mechanical polishing. Lucitone- 199 resin demonstrated the highest overall transverse strength for the materials tested. Heat-polymerized acrylic resins either mechanically or chemically polished, did not demonstrate significant changes in transverse strength during immersion in the disinfecting solution tested, regardless of time of immersion. Lucitone-199 resin demonstrated the highest overall transverse strength for the materials tested and significantly stronger than Acralyn-H with either type of polishing following immersion in 2% alkaline glutaraldehyde. There is a concern that immersion in chemical solutions often used for cleansing and disinfection of prostheses may undermine the strength and structure of denture base resins. In this study it was observed that, the transverse strength of samples of Lucitone-199 was higher than that of the samples of Acralyn-H. The chances of fracture of the denture made of Lucitone-199 are less than that of dentures made of Acralyn-H. The chemically polished dentures may be more prone to fracture than mechanically polished dentures.

  2. Analysis the complex interaction among flexible nanoparticles and materials surface in the mechanical polishing process

    Energy Technology Data Exchange (ETDEWEB)

    Han Xuesong, E-mail: hanxuesongphd@yahoo.com.cn [School of Mechanical Engineering, Tianjin University, 300072 (China); Gan, Yong X. [Department of Mechanical, Industrial and Manufacturing Engineering, University of Toledo, OH 43606 (United States)

    2011-02-01

    Mechanical polishing (MP), being the important technique of realizing the surface planarization, has already been widely applied in the area of microelectronic manufacturing and computer manufacturing technology. The surface planarization in the MP is mainly realized by mechanical process which depended on the microdynamic behavior of nanoparticle. The complex multibody interaction among nanoparticles and materials surface is different from interaction in the macroscopic multibody system which makes the traditional classical materials machining theory cannot accurately uncover the mystery of the surface generation in the MP. Large-scale classical molecular dynamic (MD) simulation of interaction among nanoparticles and solid surface has been carried out to investigate the physical essence of surface planarization. The particles with small impact angle can generate more uniform global planarization surface but the materials removal rate is lower. The shear interaction between particle and substrate may induce large friction torque and lead to the rotation of particle. The translation plus rotation makes the nanoparticle behaved like micro-milling tool. The results show that the nanoparticles may aggregrate together and form larger cluster thus deteriorate surface the quality. This MD simulation results illuminate that the f inal planarized surface can only be acquired by synergic behavior of all particles using various means such as cutting, impacting, scratching, indentation and so on.

  3. Preparation and certification of the Polish reference material 'Oriental Tobacco Leaves' (CTA-OTL-1) for inorganic trace analysis

    International Nuclear Information System (INIS)

    Dybczynski, R.; Polkowska-Motrenko, H.; Samczynski, Z.; Szopa, Z.

    1996-01-01

    A new Polish certified reference material 'Oriental Tobacco Leaves' (CTA-OTL-1) for inorganic trace analysis was prepared. Fresh tobacco leaves of variety 'Oriental' were dried, ground and sieved. All precautions were taken to avoid contamination of material with metals. The next step was homogenization. Preliminary homogeneity checking consisted in determining of Ca, Fe and K content by X-ray fluorescence. Final homogeneity testing was performed by neutron activation analysis determining Co, Cr, Fe and Rb. To assure long-term stability, the whole lot of material was sterilized by electron beam radiation. Certification of the candidate reference material was done on the basis of world-wide interlaboratory comparisons exercise in which 61 laboratories, using various analytical methods participated. (author). 30 refs, 12 tabs, 21 figs

  4. Contribution of NAA and other techniques to the certification of two new Polish CRMs prepared by INCT

    International Nuclear Information System (INIS)

    Dybczynski, R.; Danko, B.; Kulisa, K.; Maleszewska, E.; Polkowska-Motrenko, H.; Samczynski, Z.; Szopa, Z.

    2002-01-01

    Two new reference materials of biological origin, namely Tea Leaves (INCTTL-1 ) and Mixed Polish Herbs (INCT-MPH-2), were prepared, and a worldwide interlaboratory comparison in which more than 100 laboratories participated was organized with the aim to certify these materials for the content of possibly a great number of trace elements. In this paper a preliminary analysis of the contribution of various analytical techniques to the certification of the new reference materials is presented and discussed with special emphasis on the role played by neutron activation analysis (NAA) and other radiometric techniques. The significance of 'very accurate methods' by radiochemical NAA in the certification process is pointed out. An attempt is made to compare the outcome of the present intercomparison with those formerly organized by INCT as well as with some earlier IAEA intercomparisons in order to demonstrate similarities, differences and trends in the use of the various analytical techniques in trace analysis as a function of time. (author)

  5. Preparation and certification of the Polish reference material `Oriental Tobacco Leaves` (CTA-OTL-1) for inorganic trace analysis

    Energy Technology Data Exchange (ETDEWEB)

    Dybczynski, R.; Polkowska-Motrenko, H.; Samczynski, Z.; Szopa, Z. [Institute of Nuclear Chemistry and Technology, Warsaw (Poland)

    1996-12-31

    A new Polish certified reference material `Oriental Tobacco Leaves` (CTA-OTL-1) for inorganic trace analysis was prepared. Fresh tobacco leaves of variety `Oriental` were dried, ground and sieved. All precautions were taken to avoid contamination of material with metals. The next step was homogenization. Preliminary homogeneity checking consisted in determining of Ca, Fe and K content by X-ray fluorescence. Final homogeneity testing was performed by neutron activation analysis determining Co, Cr, Fe and Rb. To assure long-term stability, the whole lot of material was sterilized by electron beam radiation. Certification of the candidate reference material was done on the basis of world-wide interlaboratory comparisons exercise in which 61 laboratories, using various analytical methods participated. (author). 30 refs, 12 tabs, 21 figs.

  6. Preparation, mechanical strengths, and thermal

    Science.gov (United States)

    Inoue, A.; Furukawa, S.; Hagiwara, M.; Masumoto, T.

    1987-05-01

    Ni-based amorphous wires with good bending ductility have been prepared for Ni75Si8B17 and Ni78P12B10 alloys containing 1 to 2 at. pct Al or Zr by melt spinning in rotating water. The enhancement of the wire-formation tendency by the addition of Al has been clarified to be due to the increase in the stability of the melt jet through the formation of a thin A12O3 film on the outer surface. The maximum wire diameter is about 190 to 200 μm for the Ni-Si (or P)-B-Al alloys and increases to about 250 μm for the Ni-Si-B-Al-Cr alloys containing 4 to 6 at. pct Cr. The tensile fracture strength and fracture elongation are 2730 MPa and 2.9 pct for (Ni0.75Si0.08B0.17 99Al1) wire and 2170 MPa and 2.4 pct for (Ni0.78P0.12B0.1)99Al1 wire. These wires exhibit a fatigue limit under dynamic bending strain in air with a relative humidity of 65 pct; this limit is 0.50 pct for a Ni-Si-B-Al wire, which is higher by 0.15 pct than that of a Fe75Si10B15 amorphous wire. Furthermore, the Ni-base wires do not fracture during a 180-deg bending even for a sample annealed at temperatures just below the crystallization temperature, in sharp contrast to high embrittlement tendency for Fe-base amorphous alloys. Thus, the Ni-based amorphous wires have been shown to be an attractive material similar to Fe- and Co-based amorphous wires because of its high static and dynamic strength, high ductility, high stability to thermal embrittlement, and good corrosion resistance.

  7. Reduction of Residual Stresses in Sapphire Cover Glass Induced by Mechanical Polishing and Laser Chamfering Through Etching

    Directory of Open Access Journals (Sweden)

    Shih-Jeh Wu

    2016-10-01

    Full Text Available Sapphire is a hard and anti-scratch material commonly used as cover glass of mobile devices such as watches and mobile phones. A mechanical polishing using diamond slurry is usually necessary to create mirror surface. Additional chamfering at the edge is sometimes needed by mechanical grinding. These processes induce residual stresses and the mechanical strength of the sapphire work piece is impaired. In this study wet etching by phosphate acid process is applied to relief the induced stress in a 1” diameter sapphire cover glass. The sapphire is polished before the edge is chamfered by a picosecond laser. Residual stresses are measured by laser curvature method at different stages of machining. The results show that the wet etching process effectively relief the stress and the laser machining does not incur serious residual stress.

  8. Adsorption treatment of oxide chemical mechanical polishing wastewater from a semiconductor manufacturing plant by electrocoagulation

    Energy Technology Data Exchange (ETDEWEB)

    Chou, Wei-Lung, E-mail: wlchou@sunrise.hk.edu.tw [Department of Safety, Health and Environmental Engineering, Hungkuang University, No. 34, Chung-Chie Road, Sha-Lu, Taichung 433, Taiwan (China); Wang, Chih-Ta [Department of Safety Health and Environmental Engineering, Chung Hwa University of Medical Technology, Tainan Hsien 717, Taiwan (China); Chang, Wen-Chun; Chang, Shih-Yu [Department of Safety, Health and Environmental Engineering, Hungkuang University, No. 34, Chung-Chie Road, Sha-Lu, Taichung 433, Taiwan (China)

    2010-08-15

    In this study, metal hydroxides generated during electrocoagulation (EC) were used to remove the chemical oxygen demand (COD) of oxide chemical mechanical polishing (oxide-CMP) wastewater from a semiconductor manufacturing plant by EC. Adsorption studies were conducted in a batch system for various current densities and temperatures. The COD concentration in the oxide-CMP wastewater was effectively removed and decreased by more than 90%, resulting in a final wastewater COD concentration that was below the Taiwan discharge standard (100 mg L{sup -1}). Since the processed wastewater quality exceeded the direct discharge standard, the effluent could be considered for reuse. The adsorption kinetic studies showed that the EC process was best described using the pseudo-second-order kinetic model at the various current densities and temperatures. The experimental data were also tested against different adsorption isotherm models to describe the EC process. The Freundlich adsorption isotherm model predictions matched satisfactorily with the experimental observations. Thermodynamic parameters, including the Gibbs free energy, enthalpy, and entropy, indicated that the COD adsorption of oxide-CMP wastewater on metal hydroxides was feasible, spontaneous and endothermic in the temperature range of 288-318 K.

  9. Adsorption treatment of oxide chemical mechanical polishing wastewater from a semiconductor manufacturing plant by electrocoagulation

    International Nuclear Information System (INIS)

    Chou, Wei-Lung; Wang, Chih-Ta; Chang, Wen-Chun; Chang, Shih-Yu

    2010-01-01

    In this study, metal hydroxides generated during electrocoagulation (EC) were used to remove the chemical oxygen demand (COD) of oxide chemical mechanical polishing (oxide-CMP) wastewater from a semiconductor manufacturing plant by EC. Adsorption studies were conducted in a batch system for various current densities and temperatures. The COD concentration in the oxide-CMP wastewater was effectively removed and decreased by more than 90%, resulting in a final wastewater COD concentration that was below the Taiwan discharge standard (100 mg L -1 ). Since the processed wastewater quality exceeded the direct discharge standard, the effluent could be considered for reuse. The adsorption kinetic studies showed that the EC process was best described using the pseudo-second-order kinetic model at the various current densities and temperatures. The experimental data were also tested against different adsorption isotherm models to describe the EC process. The Freundlich adsorption isotherm model predictions matched satisfactorily with the experimental observations. Thermodynamic parameters, including the Gibbs free energy, enthalpy, and entropy, indicated that the COD adsorption of oxide-CMP wastewater on metal hydroxides was feasible, spontaneous and endothermic in the temperature range of 288-318 K.

  10. Adsorption treatment of oxide chemical mechanical polishing wastewater from a semiconductor manufacturing plant by electrocoagulation.

    Science.gov (United States)

    Chou, Wei-Lung; Wang, Chih-Ta; Chang, Wen-Chun; Chang, Shih-Yu

    2010-08-15

    In this study, metal hydroxides generated during electrocoagulation (EC) were used to remove the chemical oxygen demand (COD) of oxide chemical mechanical polishing (oxide-CMP) wastewater from a semiconductor manufacturing plant by EC. Adsorption studies were conducted in a batch system for various current densities and temperatures. The COD concentration in the oxide-CMP wastewater was effectively removed and decreased by more than 90%, resulting in a final wastewater COD concentration that was below the Taiwan discharge standard (100 mg L(-1)). Since the processed wastewater quality exceeded the direct discharge standard, the effluent could be considered for reuse. The adsorption kinetic studies showed that the EC process was best described using the pseudo-second-order kinetic model at the various current densities and temperatures. The experimental data were also tested against different adsorption isotherm models to describe the EC process. The Freundlich adsorption isotherm model predictions matched satisfactorily with the experimental observations. Thermodynamic parameters, including the Gibbs free energy, enthalpy, and entropy, indicated that the COD adsorption of oxide-CMP wastewater on metal hydroxides was feasible, spontaneous and endothermic in the temperature range of 288-318 K. Copyright 2010 Elsevier B.V. All rights reserved.

  11. Manipulating mammalian cell morphologies using chemical-mechanical polished integrated circuit chips

    Science.gov (United States)

    Moussa, Hassan I.; Logan, Megan; Siow, Geoffrey C.; Phann, Darron L.; Rao, Zheng; Aucoin, Marc G.; Tsui, Ting Y.

    2017-12-01

    Tungsten chemical-mechanical polished integrated circuits were used to study the alignment and immobilization of mammalian (Vero) cells. These devices consist of blanket silicon oxide thin films embedded with micro- and nano-meter scale tungsten metal line structures on the surface. The final surfaces are extremely flat and smooth across the entire substrate, with a roughness in the order of nanometers. Vero cells were deposited on the surface and allowed to adhere. Microscopy examinations revealed that cells have a strong preference to adhere to tungsten over silicon oxide surfaces with up to 99% of cells adhering to the tungsten portion of the surface. Cells self-aligned and elongated into long threads to maximize contact with isolated tungsten lines as thin as 180 nm. The orientation of the Vero cells showed sensitivity to the tungsten line geometric parameters, such as line width and spacing. Up to 93% of cells on 10 μm wide comb structures were aligned within ± 20° of the metal line axis. In contrast, only 22% of cells incubated on 0.18 μm comb patterned tungsten lines were oriented within the same angular interval. This phenomenon is explained using a simple model describing cellular geometry as a function of pattern width and spacing, which showed that cells will rearrange their morphology to maximize their contact to the embedded tungsten. Finally, it was discovered that the materials could be reused after cleaning the surfaces, while maintaining cell alignment capability.

  12. The way to zeros: The future of semiconductor device and chemical mechanical polishing technologies

    Science.gov (United States)

    Tsujimura, Manabu

    2016-06-01

    For the last 60 years, the development of cutting-edge semiconductor devices has strongly emphasized scaling; the effort to scale down current CMOS devices may well achieve the target of 5 nm nodes by 2020. Planarization by chemical mechanical polishing (CMP), is one technology essential for supporting scaling. This paper summarizes the history of CMP transitions in the planarization process as well as the changing degree of planarity required, and, finally, introduces innovative technologies to meet the requirements. The use of CMP was triggered by the replacement of local oxidation of silicon (LOCOS) as the element isolation technology by shallow trench isolation (STI) in the 1980s. Then, CMP’s use expanded to improving embedability of aluminum wiring, tungsten (W) contacts, Cu wiring, and, more recently, to its adoption in high-k metal gate (HKMG) and FinFET (FF) processes. Initially, the required degree of planarity was 50 nm, but now 0 nm is required. Further, zero defects on a post-CMP wafer is now the goal, and it is possible that zero psi CMP loading pressure will be required going forward. Soon, it seems, everything will have to be “zero” and perfect. Although the process is also chemical in nature, the CMP process is actually mechanical with a load added using slurry particles several tens of nm in diameter. Zero load in the loading process, zero nm planarity with no trace of processing, and zero residual foreign material, including the very slurry particles used in the process, are all required. This article will provide an overview of how to achieve these new requirements and what technologies should be employed.

  13. Fabrication of ruthenium thin film and characterization of its chemical mechanical polishing process

    International Nuclear Information System (INIS)

    Chou, Yi-Sin; Yen, Shi-Chern; Jeng, King-Tsai

    2015-01-01

    The fabrication of Ru thin film is conducted on titanium (Ti)-based rotating disk electrodes (RDE) by electrodeposition and characteristics of its chemical mechanical polishing (CMP) are investigated to be employed for copper diffusion layer applications in various semiconductor-device interconnects. The electrodeposits obtained under different electrodeposition conditions are characterized using atomic force microscope (AFM) and field emission scanning electron microscope (FESEM). Experimental results indicate that the Ru electrodeposition exhibits a Tafel behavior with a 2e metal ion reduction process. Both exchange current density and cathodic transfer coefficient are determined. A quasi Koutecky–Levich analysis is proposed to analyze the electrodeposition processes under different applied current density conditions and the activation overpotentials together with electrodeposition rate constants are obtained. For Ru CMP operations, slurries containing metal-free 2wt% ammonium persulfate and 2wt% silica abrasive at various pH values are employed. Potentiodynamic polarization studies indicate that the corrosion current density varies in the presence of ammonia while the static etch rate remains low. Both chemical and mechanical effects are investigated and analyzed, and the CMP efficacy factors are obtained. - Highlights: • Ru electrodeposition is a 2e metal ion reduction process with Tafel behavior. • Ru electrodeposition on Ti RDE fits a quasi Koutecky–Levich equation. • Metal-free slurry is employed for CMP operation to avoid contamination. • The Ru CMP process is affected by the surface condition and the pH of slurry. • The CMP efficacy factor should be high in order to obtain a smooth surface

  14. Fabrication of ruthenium thin film and characterization of its chemical mechanical polishing process

    Energy Technology Data Exchange (ETDEWEB)

    Chou, Yi-Sin [Department of Chemical Engineering, National Taiwan University, Taipei 10617, Taiwan (China); Yen, Shi-Chern, E-mail: scyen@ntu.edu.tw [Department of Chemical Engineering, National Taiwan University, Taipei 10617, Taiwan (China); Jeng, King-Tsai [Research Division I, TIER, 7F, No. 16-8, Dehuei St., Taipei 10461, Taiwan (China)

    2015-07-15

    The fabrication of Ru thin film is conducted on titanium (Ti)-based rotating disk electrodes (RDE) by electrodeposition and characteristics of its chemical mechanical polishing (CMP) are investigated to be employed for copper diffusion layer applications in various semiconductor-device interconnects. The electrodeposits obtained under different electrodeposition conditions are characterized using atomic force microscope (AFM) and field emission scanning electron microscope (FESEM). Experimental results indicate that the Ru electrodeposition exhibits a Tafel behavior with a 2e metal ion reduction process. Both exchange current density and cathodic transfer coefficient are determined. A quasi Koutecky–Levich analysis is proposed to analyze the electrodeposition processes under different applied current density conditions and the activation overpotentials together with electrodeposition rate constants are obtained. For Ru CMP operations, slurries containing metal-free 2wt% ammonium persulfate and 2wt% silica abrasive at various pH values are employed. Potentiodynamic polarization studies indicate that the corrosion current density varies in the presence of ammonia while the static etch rate remains low. Both chemical and mechanical effects are investigated and analyzed, and the CMP efficacy factors are obtained. - Highlights: • Ru electrodeposition is a 2e metal ion reduction process with Tafel behavior. • Ru electrodeposition on Ti RDE fits a quasi Koutecky–Levich equation. • Metal-free slurry is employed for CMP operation to avoid contamination. • The Ru CMP process is affected by the surface condition and the pH of slurry. • The CMP efficacy factor should be high in order to obtain a smooth surface.

  15. XPS, UV–vis spectroscopy and AFM studies on removal mechanisms of Si-face SiC wafer chemical mechanical polishing (CMP)

    International Nuclear Information System (INIS)

    Zhou, Yan; Pan, Guoshun; Shi, Xiaolei; Xu, Li; Zou, Chunli; Gong, Hua; Luo, Guihai

    2014-01-01

    Highlights: • CMP removal mechanism of Si-face SiC wafer is investigated through XPS analysis. • UV–vis spectroscopy is used to study CMP removal mechanisms. • CMP removal model of Si-face SiC wafer is proposed. • The variations of atomic step morphology on ultra-smooth surface via AFM is studied. - Abstract: Chemical mechanical polishing (CMP) removal mechanisms of on-axis Si-face SiC wafer have been investigated through X-ray photoelectron spectroscopy (XPS), UV–visible (UV–vis) spectroscopy and atomic force microscopy (AFM). XPS results indicate that silicon oxide is formed on Si-face surface polished by the slurry including oxidant H 2 O 2 , but not that after immersing in H 2 O 2 solution. UV–vis spectroscopy curves prove that • OH hydroxyl radical could be generated only under CMP polishing by the slurry including H 2 O 2 and abrasive, so as to promote oxidation of Si-face to realize the effective removal; meanwhile, alkali KOH during CMP could induce the production of more radicals to improve the removal. On the other side, ultra-smooth polished surface with atomic step structure morphology and extremely low Ra of about 0.06 nm (through AFM) is obtained using the developed slurry with silica nanoparticle abrasive. Through investigating the variations of the atomic step morphology on the surface polished by different slurries, it's reveals that CMP removal mechanism involves a simultaneous process of surface chemical reaction and nanoparticle atomic scale abrasion

  16. Investigation on the surface characterization of Ga-faced GaN after chemical-mechanical polishing

    Energy Technology Data Exchange (ETDEWEB)

    Gong, Hua [State Key Laboratory of Tribology, Tsinghua University, Beijing 100084 (China); Shenzhen Key Laboratory of Micro/nano Manufacturing, Research Institute of Tsinghua University in Shenzhen, Shenzhen 518057 (China); Pan, Guoshun, E-mail: pangs@tsinghua.edu.cn [State Key Laboratory of Tribology, Tsinghua University, Beijing 100084 (China); Shenzhen Key Laboratory of Micro/nano Manufacturing, Research Institute of Tsinghua University in Shenzhen, Shenzhen 518057 (China); Zhou, Yan; Shi, Xiaolei; Zou, Chunli; Zhang, Suman [State Key Laboratory of Tribology, Tsinghua University, Beijing 100084 (China); Shenzhen Key Laboratory of Micro/nano Manufacturing, Research Institute of Tsinghua University in Shenzhen, Shenzhen 518057 (China)

    2015-05-30

    Highlights: • Tiny-sized nanoparticles were introduced in GaN CMP to realize a good surface. • The relationship between surface characterization and abrasive size was conducted. • An atomic step-terrace structure was achieved on GaN surface after CMP. • Pt/C catalyst nanoparticles were used in GaN CMP to get a higher MRR. - Abstract: The relationship between the surface characterization after chemical mechanical polishing (CMP) and the size of the silica (SiO{sub 2}) abrasive used for CMP of gallium nitride (GaN) substrates was investigated in detail. Atomic force microscope was used for measuring the surface morphology, pit feature, pit depth distribution, and atomic step-terrace structure. With the decrease of SiO{sub 2} abrasive size, the pit depth reduced and the atomic step-terrace structure became more whole with smaller damage area, resulting in smaller roughness. For tiny-sized SiO{sub 2} abrasive, an almost complete atomic step-terrace structure with 0.0523 nm roughness was achieved. On the other hand, in order to acquire higher removal, Pt/C nanoparticle was employed as a catalyst in CMP slurry. The result indicates that when Pt/C catalyst content was reached to 1.0 ppm, material removal rate was increased by 47.69% compared to that by none of the catalyst, and besides, the pit depth reduced and the surface atomic step-terrace structure was not destroyed. The Pt/C nanoparticle is proved to be the promising catalyst to the surface preparation of super-hard and inert materials with high efficiency and good surface.

  17. Chemical mechanical polishing of BTO thin film for vertical sidewall patterning of high-density memory capacitor

    International Nuclear Information System (INIS)

    Kim, Nam-Hoon; Ko, Pil-Ju; Seo, Yong-Jin; Lee, Woo-Sun

    2006-01-01

    Most high-k materials cannot to be etched easily. Problems such as low etch rate, poor sidewall angle, plasma damage, and process complexity have emerged in high-density DRAM fabrication. Chemical mechanical polishing (CMP) by the damascene process has been used to pattern high-k materials for high-density capacitor. Barium titanate (BTO) thin film, a typical high-k material, was polished with three types of silica slurry having different pH values. Sufficient removal rate with adequate selectivity to realize the pattern mask of tetra-ethyl ortho-silicate (TEOS) film for the vertical sidewall angle was obtained. The changes of X-ray diffraction pattern and dielectric constant by CMP process were negligible. Planarization was also achieved for the subsequent multilevel processes. Our new CMP approach will provide a guideline for effective patterning of high-k materials by CMP

  18. Influence of Wafer Edge Geometry on Removal Rate Profile in Chemical Mechanical Polishing: Wafer Edge Roll-Off and Notch

    Science.gov (United States)

    Fukuda, Akira; Fukuda, Tetsuo; Fukunaga, Akira; Tsujimura, Manabu

    2012-05-01

    In the chemical mechanical polishing (CMP) process, uniform polishing up to near the wafer edge is essential to reduce edge exclusion and improve yield. In this study, we examine the influences of inherent wafer edge geometries, i.e., wafer edge roll-off and notch, on the CMP removal rate profile. We clarify the areas in which the removal rate profile is affected by the wafer edge roll-off and the notch, as well as the intensity of their effects on the removal rate profile. In addition, we propose the use of a small notch to reduce the influence of the wafer notch and present the results of an examination by finite element method (FEM) analysis.

  19. Standards of Conditions During Preparations for the Summer Paralympic Games Between 2004 and 2012 Assessed by Polish Athletes

    Directory of Open Access Journals (Sweden)

    Sobiecka Joanna

    2015-12-01

    Full Text Available The quality of training conditions affects sporting success, injuries and health. The aim of the work was to present the conditions during the preparations of Polish athletes for the Summer Paralympic Games 2004-2012. The study encompassed 271 paralympians: Athens (91, Beijing (89 and London (91, competing in 13 disciplines. The research was based on a two-part questionnaire by Kłodecka-Różalska adjusted for disabled sports, and was conducted one month before each PG. Part 1 contained 20 closed-ended questions regarding conditions during preparations, while Part 2 concerned socio-demographic and sports-related data. Three levels of conditions: good, satisfactory and poor, were identified. The analysis showed that while the relationships between the athletes were good in all the preparatory periods, the co-operation with the paralympic coaches worsened. The standards of accommodation, food and sports facilities lowered. Personal orthopaedic supply was satisfactory in London; personal sporting equipment was good at all PG. The quality of medical care was the highest in London. The co-operation with physicians, physiotherapists and massage therapists was satisfactory. Consultations with the dietician were sporadic and assessed as poor. Psychological consultations were rare but satisfactory in Beijing and London. Contacts with the mass media were poor at all PG. Although combining private life, work, and education with sport was satisfactory, it was increasingly difficult to manage, particularly before London. The conditions during preparations for the PG 2004-2012 varied. Improvement was noticed only in the quality of medical care and personal orthopaedic supply.

  20. Standards of Conditions During Preparations for the Summer Paralympic Games Between 2004 and 2012 Assessed by Polish Athletes.

    Science.gov (United States)

    Sobiecka, Joanna; Gawroński, Wojciech; Kądziołka, Marta; Kruszelnicki, Paweł; Kłodecka-Różalska, Jadwiga; Plinta, Ryszard

    2015-11-22

    The quality of training conditions affects sporting success, injuries and health. The aim of the work was to present the conditions during the preparations of Polish athletes for the Summer Paralympic Games 2004-2012. The study encompassed 271 paralympians: Athens (91), Beijing (89) and London (91), competing in 13 disciplines. The research was based on a two-part questionnaire by Kłodecka-Różalska adjusted for disabled sports, and was conducted one month before each PG. Part 1 contained 20 closed-ended questions regarding conditions during preparations, while Part 2 concerned socio-demographic and sports-related data. Three levels of conditions: good, satisfactory and poor, were identified. The analysis showed that while the relationships between the athletes were good in all the preparatory periods, the co-operation with the paralympic coaches worsened. The standards of accommodation, food and sports facilities lowered. Personal orthopaedic supply was satisfactory in London; personal sporting equipment was good at all PG. The quality of medical care was the highest in London. The co-operation with physicians, physiotherapists and massage therapists was satisfactory. Consultations with the dietician were sporadic and assessed as poor. Psychological consultations were rare but satisfactory in Beijing and London. Contacts with the mass media were poor at all PG. Although combining private life, work, and education with sport was satisfactory, it was increasingly difficult to manage, particularly before London. The conditions during preparations for the PG 2004-2012 varied. Improvement was noticed only in the quality of medical care and personal orthopaedic supply.

  1. Mechanical bowel preparation for elective colorectal surgery

    DEFF Research Database (Denmark)

    Güenaga, Katia F; Matos, Delcio; Wille-Jørgensen, Peer

    2011-01-01

    The presence of bowel contents during colorectal surgery has been related to anastomotic leakage, but the belief that mechanical bowel preparation (MBP) is an efficient agent against leakage and infectious complications is based on observational data and expert opinions only.An enema before...... the rectal surgery to clean the rectum and facilitate the manipulation for the mechanical anastomosis is used for many surgeons. This is analysed separately...

  2. Mechanical site preparation for forest restoration

    Science.gov (United States)

    Magnus Lof; Daniel C. Dey; Rafael M. Navarro; Douglass F. Jacobs

    2012-01-01

    Forest restoration projects have become increasingly common around the world and planting trees is almost always a key component. Low seedling survival and growth may result in restoration failures and various mechanical site preparation techniques for treatment of soils and vegetation are important tools used to help counteract this. In this article, we synthesize the...

  3. Mechanical bowel preparation for elective colorectal surgery

    DEFF Research Database (Denmark)

    Güenaga, Katia F; Matos, Delcio; Wille-Jørgensen, Peer

    2011-01-01

    The presence of bowel contents during colorectal surgery has been related to anastomotic leakage, but the belief that mechanical bowel preparation (MBP) is an efficient agent against leakage and infectious complications is based on observational data and expert opinions only.An enema before...

  4. R&D progress in SRF surface preparation with centrifugal barrel polishing (cbp) for both Nb and Cu

    Energy Technology Data Exchange (ETDEWEB)

    Palczewski, Ari [JLAB

    2013-09-01

    Centrifugal Barrel polishing (CBP) is becoming a common R&D tool for SRF cavity preparation around the world. During the CBP process a cylindrically symmetric SRF cavity is filled with relatively cheap and environmentally friendly abrasive and sealed. The cavity is then spun around a cylindrically symmetric axis at high speeds uniformly conditioning the inner surface. This uniformity is especially relevant for SRF application because many times a single manufacturing defects limits cavity?s performance well below it?s theoretical limit. In addition CBP has created surfaces with roughness?s on the order of 10?s of nm which create a unique surface for wet chemistry or thin film deposition. CBP is now being utilized at Jefferson Laboratory, Fermi Laboratory and Cornell University in the US, Deutsches Elektronen-Synchrotron in Germany, Laboratori Nazionali di Legnaro in Italy, and Raja Ramanna Centre for Advanced Technology in India. In this talk we will present current CBP research from each lab including equipment, baseline recipes, cavity removal rates and subsequent cryogenic cavity tests on niobium as well as copper cavities where available.

  5. Analysis and optimization of surface profile correcting mechanism of the pitch lap in large-aperture annular polishing

    Science.gov (United States)

    Zhang, Huifang; Yang, Minghong; Xu, Xueke; Wu, Lunzhe; Yang, Weiguang; Shao, Jianda

    2017-10-01

    The surface figure control of the conventional annular polishing system is realized ordinarily by the interaction between the conditioner and the lap. The surface profile of the pitch lap corrected by the marble conditioner has been measured and analyzed as a function of kinematics, loading conditions, and polishing time. The surface profile measuring equipment of the large lap based on laser alignment was developed with the accuracy of about 1μm. The conditioning mechanism of the conditioner is simply determined by the kinematics and fully fitting principle, but the unexpected surface profile deviation of the lap emerged frequently due to numerous influencing factors including the geometrical relationship, the pressure distribution at the conditioner/lap interface. Both factors are quantitatively evaluated and described, and have been combined to develop a spatial and temporal model to simulate the surface profile evolution of pitch lap. The simulations are consistent with the experiments. This study is an important step toward deterministic full-aperture annular polishing, providing a beneficial guidance for the surface profile correction of the pitch lap.

  6. Modeling the effects of cohesive energy for single particle on the material removal in chemical mechanical polishing at atomic scale

    International Nuclear Information System (INIS)

    Wang Yongguang; Zhao Yongwu; An Wei; Wang Jun

    2007-01-01

    This paper proposes a novel mathematical model for chemical mechanical polishing (CMP) based on interface solid physical and chemical theory in addition to energy equilibrium knowledge. And the effects of oxidation concentration and particle size on the material removal in CMP are investigated. It is shown that the mechanical energy and removal cohesive energy couple with the particle size, and being a cause of the non-linear size-removal rate relation. Furthermore, it also shows a nonlinear dependence of removal rate on removal cohesive energy. The model predictions are in good qualitative agreement with the published experimental data. The current study provides an important starting point for delineating the micro-removal mechanism in the CMP process at atomic scale

  7. RNA-Seq and iTRAQ Reveal the Dwarfing Mechanism of Dwarf Polish Wheat (Triticum polonicum L.).

    Science.gov (United States)

    Wang, Yi; Xiao, Xue; Wang, Xiaolu; Zeng, Jian; Kang, Houyang; Fan, Xing; Sha, Lina; Zhang, Haiqin; Zhou, Yonghong

    2016-01-01

    The dwarfing mechanism of Rht-dp in dwarf Polish wheat (DPW) is unknown. Each internode of DPW was significantly shorter than it in high Polish wheat (HPW), and the dwarfism was insensitive to photoperiod, abscisic acid (ABA), gibberellin (GA), cytokinin (CK), auxin and brassinolide (BR). To understand the mechanism, three sets of transcripts, DPW, HPW, and a chimeric set (a combination of DPW and HPW), were constructed using RNA sequencing (RNA-Seq). Based on the chimeric transcripts, 2,446 proteins were identified using isobaric tags for relative and absolute quantification (iTRAQ). A total of 108 unigenes and 12 proteins were considered as dwarfism-related differentially expressed genes (DEGs) and differentially expressed proteins (DEPs), respectively. Among of these DEGs and DEPs, 6 DEGs and 6 DEPs were found to be involved in flavonoid and S-adenosyl-methionine (SAM) metabolisms; 5 DEGs and 3 DEPs were involved in cellulose metabolism, cell wall plasticity and cell expansion; 2 DEGs were auxin transporters; 2 DEPs were histones; 1 DEP was a peroxidase. These DEGs and DEPs reduced lignin and cellulose contents, increased flavonoid content, possibly decreased S-adenosyl-methionine (SAM) and polyamine contents and increased S-adenosyl-L-homocysteine hydrolase (SAHH) content in DPW stems, which could limit auxin transport and reduce extensibility of the cell wall, finally limited cell expansion (the cell size of DPW was significantly smaller than HPW cells) and caused dwarfism in DPW.

  8. Mechanical bowel preparation for elective colorectal surgery

    DEFF Research Database (Denmark)

    Guenaga, Katia K F G; Matos, Delcio; Wille-Jørgensen, Peer

    2009-01-01

    BACKGROUND: The presence of bowel contents during surgery has been related to anastomotic leakage, but the belief that mechanical bowel preparation (MBP) is an efficient agent against leakage and infectious complications is based on observational data and expert opinions only. OBJECTIVES...... with no MBP. Primary outcomes included anastomosis leakage - both rectal and colonic - and combined figures. Secondary outcomes included mortality, peritonitis, reoperation, wound infection, extra-abdominal complications, and overall surgical site infections. DATA COLLECTION AND ANALYSIS: Data were......: Four new trials were included at this update (total 13 RCTs with 4777 participants; 2390 allocated to MBP (Group A), and 2387 to no preparation (Group B), before elective colorectal surgery) .Anastomotic leakage occurred:(i) in 10.0% (14/139) of Group A, compared with 6.6% (9/136) of Group B for low...

  9. Nd{sup 3+}-doped colloidal SiO{sub 2} composite abrasives: Synthesis and the effects on chemical mechanical polishing (CMP) performances of sapphire wafers

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Tingting; Lei, Hong, E-mail: hong_lei2005@aliyun.com

    2017-08-15

    Highlights: • The novel Nd{sup 3+}-doped colloidal SiO{sub 2} abrasives were synthesized by seed-introduced method. • The Nd{sup 3+}-doped colloidal SiO{sub 2} abrasives exhibited lower Ra and higher MRR on sapphire during CMP. • The cores SiO{sub 2} were coated by the shells (SiO{sub 2}, Nd{sub 2}Si{sub 2}O{sub 7} and Nd(OH){sub 3}) via chemical bonds and hydrogen bonds. • XPS analysis revealed the solid-state chemical reaction between Nd{sup 3+}-doped colloidal SiO{sub 2} abrasives and sapphire during CMP. - Abstract: Abrasive is one of the most important factors in chemical mechanical polishing (CMP). In order to improve the polishing qualities of sapphire substrates, the novel Nd{sup 3+}-doped colloidal SiO{sub 2} composite abrasives were prepared by seed-induced growth method. In this work, there were a series of condensation reactions during the synthesis process of Nd{sup 3+}-doped colloidal SiO{sub 2} composite abrasives and the silica cores were coated by shells (which contains SiO{sub 2}, Nd{sub 2}Si{sub 2}O{sub 7} and Nd(OH){sub 3}) via chemical bonds and hydrogen bonds in the Nd{sup 3+}-doped colloidal SiO{sub 2} composite abrasives, which made the composite abrasives’ core-shell structure more sTable Scanning electron microscopy (SEM) showed that Nd{sup 3+}-doped colloidal SiO{sub 2} composite abrasives were spherical and uniform in size. And the acting mechanisms of Nd{sup 3+}-doped colloidal SiO{sub 2} composite abrasives on sapphire in CMP were investigated. Time-of-flight secondary ion mass spectroscopy (TOF-SIMS) analysis and X-ray photoelectron spectroscopy (XPS) analysis demonstrated that the solid-state chemical reactions between the shells (which contained SiO{sub 2}, Nd{sub 2}Si{sub 2}O{sub 7} and Nd(OH){sub 3}) of Nd{sup 3+}-doped colloidal SiO{sub 2} composite abrasives and the sapphire occurred during the CMP process. Furthermore, Nd{sup 3+}-doped colloidal SiO{sub 2} composite abrasives exhibited lower surface roughness and

  10. Preparation and certification of the Polish reference material Virginia Tobacco Leaves (CTA-VTL-2) for inorganic trace analysis including microanalysis

    Energy Technology Data Exchange (ETDEWEB)

    Dybczynski, R.; Polkowska-Motrenko, H.; Samczynski, Z.; Szopa, Z.

    1997-12-31

    A new Polish certified reference material Virginia Tobacco Leaves (CTA-VTL-2) for inorganic trace analysis including microanalysis has been prepared. Certification of the candidate reference material was based on the world-wide interlaboratory comparison in which 60 laboratories from 18 countries, participated using various analytical methods and techniques. Data evaluation performed by means of the new multifunctional software package -SSQC. Recommended values were assigned for 33 and `information` values for 10 elements, respectively. The validity of `certified` values was confirmed for several elements using `very accurate` methods developed in this Laboratory. (author). 47 refs, 28 figs, 12 tabs.

  11. Preparation and certification of the Polish reference material Virginia Tobacco Leaves (CTA-VTL-2) for inorganic trace analysis including microanalysis

    International Nuclear Information System (INIS)

    Dybczynski, R.; Polkowska-Motrenko, H.; Samczynski, Z.; Szopa, Z.

    1997-01-01

    A new Polish certified reference material Virginia Tobacco Leaves (CTA-VTL-2) for inorganic trace analysis including microanalysis has been prepared. Certification of the candidate reference material was based on the world-wide interlaboratory comparison in which 60 laboratories from 18 countries, participated using various analytical methods and techniques. Data evaluation performed by means of the new multifunctional software package -SSQC. Recommended values were assigned for 33 and 'information' values for 10 elements, respectively. The validity of 'certified' values was confirmed for several elements using 'very accurate' methods developed in this Laboratory. (author)

  12. The effect of mechanical load cycling and polishing time on microleakage of class V glass-ionomer and composite restorations: A scanning electron microscopy evaluation

    Directory of Open Access Journals (Sweden)

    Mansoreh Mirzaie

    2014-01-01

    Full Text Available Background: Microleakage is one of the challenging concerns in direct filling restorations. Understanding of its related factors is important in clinical practice. The aim of this study was scanning electron microscopy (SEM evaluation of marginal integrity in three types of tooth-colored restorative materials in class V cavity preparations and the effect of load cycling and polishing time on the microleakage. Materials and Methods: In this in vitro experimental study, class V cavity preparations were prepared on the buccal and lingual surfaces of 60 bovine incisors. The specimens were divided into three groups each containing 20 teeth: group 1: Filtek Z350, Group 2: Fuji IX/G Coat Plus, Group 3: Fuji II LC/GC varnish. In each group, 2 subgroups (n = 20 were established based on finishing time (immediate or delayed by 24 h. All specimens were thermocycled (×2,000, 5-50°C. In each sub groups, half of the teeth were load cycled. Epoxy resin replicas of 24 specimens were evaluated under field emission-SEM and interfacial gaps were measured. All teeth were then immersed in 0.5% basic fuchsin dye for 24 h, sectioned and observed under stereomicroscope. Data were analyzed with Kruskal-Wallis′ test and Mann-Whitney U test and a comparison between incisal and cervical microleakage was made with Wilcoxon test. P < 0.05 was considered as significant. Results: Load cycling and filling material had a significant effect on microleakage, but polishing time did not. Cervical microleakage in Z350/load cycle/immediate polish and Fuji IX/load cycle/immediate or delayed polish and Fuji IX/no load cycle/immediate polish were significantly higher than incisal microleakage. Conclusion: It was concluded that the cervical sealing ability of Fuji IX under load cycling was better than Fuji II LC. Under load cycling and immediate polishing Z350 showed better marginal integrity than both Fuji II LC and Fuji IX. The immediate polishing didn′t cause a statistically

  13. Polish visit

    CERN Document Server

    2003-01-01

    On 6 October, Professor Michal Kleiber, Polish Minister of Science and Chairman of the State Committee for Scientific Research, visited CERN and met both the current and designated Director General, Luciano Maiani and Robert Aymar. Professor Kleiber visited the CMS and ATLAS detector assembly halls, the underground cavern for ATLAS, and the LHC superconducting magnet string test hall. Michal Kleiber (left), Polish minister of science and Jan Krolikowski, scientist at Warsaw University and working for CMS, who shows the prototypes of the Muon Trigger board of CMS.

  14. POLISH FARM MACHINERY MARKET AFTER ACCESSION TO THE EUROPEAN UNION – PRODUCTION AND SUPPLY OF MEANS OF AGRICULTURAL MECHANIZATION

    Directory of Open Access Journals (Sweden)

    Jan Pawlak

    2014-09-01

    Full Text Available After accession to the EU in 2004 the demand for tractors and agricultural implements has grown, followed by increasing supply of them. In 2012, the supply of brand-new agricultural tractors was by 185.4% higher than in 2003. In 2012 the value of renovation index of tractor fleet in agriculture was by 149.3% higher than in 2003. In spite of significant increase of demand for tractors, their production in 2012 was by 39.2% lower than in 2003. The downfall in number of tractors produced in Poland caused that imported tractors achieved more and more important share in supplies on Polish market. In 2003 the share of imports amounted to 64.0% and in 2012 – 91.4%. Production of most other means of agricultural mechanization was in 2012 higher than in 2003. The increase in a case of manure spreaders amounted to 704.3%; self loading or unloading agricultural tractor trailers – 362.1%; fertilizer spreader – 335.2%; field sowing machines – 245.3%; pick-up balers – 222.1% and harvester threshers – 194.8. Decreases were noted in cases of steamers – by 73.3%; potato planters – by 49.7%; harrows other than disc ones – by 42.2%; potato diggers – by 31.2% and rototillers – by 22.8%.

  15. Study on the Effects of Corrosion Inhibitor According to the Functional Groups for Cu Chemical Mechanical Polishing in Neutral Environment

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Sang Won; Kim, Jae Jeong [Institute of Chemical Process, Seoul National University, Seoul (Korea, Republic of)

    2015-08-15

    As the aluminum (Al) metallization process was replaced with copper (Cu), the damascene process was introduced, which required the planarization step to eliminate over-deposited Cu with Chemical Mechanical Polishing (CMP) process. In this study, the verification of the corrosion inhibitors, one of the Cu CMP slurry components, was conducted to find out the tendency regarding the carboxyl and amino functional group in neutral environment. Through the results of etch rate, removal rate, and chemical ability of corrosion inhibitors based on 1H-1,2,4-triazole as the base corrosion inhibitor, while the amine functional group presents high Cu etching ability, carboxyl functional group shows lower Cu etching ability than base-corrosion inhibitor which means that it increases passivation effect by making strong passivation layer. It implies that the corrosion inhibitor with amine functional group was proper to apply for 1st Cu CMP slurry owing to the high etch rate and with carboxyl functional group was favorable for the 2nd Cu CMP slurry due to the high Cu removal rate/dissolution rate ratio.

  16. Self-reported preparation of Polish midwives for independent performance of prophylactic activities within the scope of women's diseases and obstetric pathologies.

    Science.gov (United States)

    Iwanowicz-Palus, Grażyna J; Rzońca, Ewa; Bień, Agnieszka; Włoszczak-Szubzda, Anna

    2014-01-01

    The objective of the study is an attempt to recognize self-reported preparation of midwives for an independent performance of prophylactic activities within the scope of women's diseases and obstetric pathologies. The study was conducted in a representative all-Polish population sample of 3,569 midwives, by the method of a diagnostic survey using a questionnaire technique. The research instrument was a questionnaire form designed by the author containing items concerning the characteristics of respondents and the object of the study, constructed based on the 5-point Liker scale. The relationships between the variables were verified using chi-square test (χ(2)) of independence. The p values pindependent performance of prophylactic activities in the area of women's diseases (84.28%) and obstetric pathologies (77.95%). However, nearly every tenth midwife, irrespective of the region of Poland where she lives, age, and participation in post-graduate training, is not prepared for an independent performance of the prevention of women's diseases. In turn, the lack of preparation for carrying out prevention of women's diseases was admitted mainly by midwives from the northern and central regions of Poland, aged 31-40, possessing post-secondary school education, who did not participate in any form of post-graduate training. The results of studies and analysis of the relevant literature indicate that it is necessary for midwives to improve their qualifications in the area of prophylaxis of women's diseases and obstetric pathologies through participation in various forms of post-graduate education.

  17. Highly-productive mechanization systems for coal mining in the Polish coal industry

    Energy Technology Data Exchange (ETDEWEB)

    Sikora, W

    1985-01-01

    Effects of mechanization on underground coal mining in Poland from 1960 to 1980 and mining equipment used in Poland is reviewed. In 1983 black coal output increased to 191.1 Mt. There were 765 working faces, 442 of which with powered supports. Six hundred thirty-four shearer loaders were in use. About 82.7% of coal output fell on faces mined by sets of mining equipment (shearer loaders, powered supports and chain conveyors). The average coal output per working face amounted to 889 t/d. About 50% of mine roadways was driven by heading machines (346 heading machines were in use). The average coal output per face mined by a set of mining equipment amounted to 1248 t/d. About 86% of shearer loaders fell on double drum shearer loaders. Types of mining equipment used in underground mining are reviewed: powered supports (Pioma, Fazos, Glinik and the SOW), shearer loaders (drum shearer loaders and double-drum shearer loaders with chain haulage and chainless haulage systems for unidirectional and bi-directional mining), chain conveyors (Samson, Rybnik). Statistical data on working faces with various sets of equipment are given. 3 references.

  18. Effect of strain rate and temperature on mechanical properties of selected building Polish steels

    Directory of Open Access Journals (Sweden)

    Moćko Wojciech

    2015-01-01

    Full Text Available Currently, the computer programs of CAD type are basic tool for designing of various structures under impact loading. Application of the numerical calculations allows to substantially reduce amount of time required for the design stage of such projects. However, the proper use of computer aided designing technique requires input data for numerical software including elastic-plastic models of structural materials. This work deals with the constitutive model developed by Rusinek and Klepaczko (RK applied for the modelling of mechanical behaviour of selected grades structural St0S, St3SX, 18GS and 34GS steels and presents here results of experimental and empirical analyses to describe dynamic elastic-plastic behaviours of tested materials at wide range of temperature. In order to calibrate the RK constitutive model, series of compression tests at wide range of strain rates, including static, quasi-static and dynamic investigations at lowered, room and elevated temperatures, were carried out using two testing stands: servo-hydraulic machine and split Hopkinson bar. The results were analysed to determine influence of temperature and strain rate on visco-plastic response of tested steels, and show good correlation with experimental data.

  19. Preparation, characterization and mechanical properties of k ...

    Indian Academy of Sciences (India)

    2017-06-09

    Jun 9, 2017 ... Nanocomposite; k-Carrageenan; SiO2 nanoparticles; mechanical strength; antimicrobial activity. 1. Introduction ... Silicon dioxide (SiO2)-filled polymer matrix com- posites have ... by using the agar disk diffusion method. 2.

  20. Self-reported preparation of Polish midwives for independent performance of prophylactic activities within the scope of women’s diseases and obstetric pathologies

    Directory of Open Access Journals (Sweden)

    Grażyna J. Iwanowicz-Palus

    2014-06-01

    Full Text Available objective. The objective of the study is an attempt to recognize self-reported preparation of midwives for an independent performance of prophylactic activities within the scope of women’s diseases and obstetric pathologies. material and methods. The study was conducted in a representative all-Polish population sample of 3,569 midwives, by the method of a diagnostic survey using a questionnaire technique. The research instrument was a questionnaire form designed by the author containing items concerning the characteristics of respondents and the object of the study, constructed based on the 5-point Liker scale. The relationships between the variables were verified using chi-square test (χ [sup]2[/sup] of independence. The p values p<0.05 were considered statistically significant. results. Analysis of results allows the presumption that in the opinions of midwives the majority of them are prepared for the independent performance of prophylactic activities in the area of women’s diseases (84.28% and obstetric pathologies (77.95%. However, nearly every tenth midwife, irrespective of the region of Poland where she lives, age, and participation in post-graduate training, is not prepared for an independent performance of the prevention of women’s diseases. In turn, the lack of preparation for carrying out prevention of women’s diseases was admitted mainly by midwives from the northern and central regions of Poland, aged 31–40, possessing post-secondary school education, who did not participate in any form of post-graduate training. conclusions. The results of studies and analysis of the relevant literature indicate that it is necessary for midwives to improve their qualifications in the area of prophylaxis of women’s diseases and obstetric pathologies through participation in various forms of post-graduate education

  1. Zerodur polishing process for high surface quality and high efficiency

    International Nuclear Information System (INIS)

    Tesar, A.; Fuchs, B.

    1992-08-01

    Zerodur is a glass-ceramic composite importance in applications where temperature instabilities influence optical and mechanical performance, such as in earthbound and spaceborne telescope mirror substrates. Polished Zerodur surfaces of high quality have been required for laser gyro mirrors. Polished surface quality of substrates affects performance of high reflection coatings. Thus, the interest in improving Zerodur polished surface quality has become more general. Beyond eliminating subsurface damage, high quality surfaces are produced by reducing the amount of hydrated material redeposited on the surface during polishing. With the proper control of polishing parameters, such surfaces exhibit roughnesses of < l Angstrom rms. Zerodur polishing was studied to recommend a high surface quality polishing process which could be easily adapted to standard planetary continuous polishing machines and spindles. This summary contains information on a polishing process developed at LLNL which reproducibly provides high quality polished Zerodur surfaces at very high polishing efficiencies

  2. Vestibule and Cask Preparation Mechanical Handling Calculation

    International Nuclear Information System (INIS)

    Ambre, N.

    2004-01-01

    The scope of this document is to develop the size, operational envelopes, and major requirements of the equipment to be used in the vestibule, cask preparation area, and the crane maintenance area of the Fuel Handling Facility. This calculation is intended to support the License Application (LA) submittal of December 2004, in accordance with the directive given by DOE correspondence received on the 27th of January 2004 entitled: ''Authorization for Bechtel SAIC Company L.L.C. to Include a Bare Fuel Handling Facility and Increased Aging Capacity in the License Application, Contract Number DE-AC--28-01R W12101'' (Ref. 167124). This correspondence was appended by further correspondence received on the 19th of February 2004 entitled: ''Technical Direction to Bechtel SAIC Company L.L. C. for Surface Facility Improvements, Contract Number DE-AC--28-01R W12101; TDL No. 04-024'' (Ref. 16875 1). These documents give the authorization for a Fuel Handling Facility to be included in the baseline. The limitations of this preliminary calculation lie within the assumptions of section 5 , as this calculation is part of an evolutionary design process

  3. Dietary risk evaluation for 28 polycyclic aromatic hydrocarbons (PAHs) in tea preparations made of teas available on the Polish retail market.

    Science.gov (United States)

    Roszko, Marek; Kamińska, Marta; Szymczyk, Krystyna; Jędrzejczak, Renata

    2018-01-02

    The aim of this work was to assess dietary risk resulting from consumption of polycyclic aromatic hydrocarbons (PAHs) with tea infusions. To this end, levels of 28 PAHs in black, green, red and white teas available on the Polish retail market have been assessed. Profiles and correlation between concentrations of individual PAHs have been identified. A model study on transfer of PAHs from tea leaves into tea preparations has been conducted. Relatively high concentrations of 28 evaluated PAHs have been found in 58 tested samples of black, green, red and white teas sampled on the Polish retail market. Total concentration ∑28PAH ranged from 57 to 696 µg kg -1 with mean 258 µg kg -1 (dry tea leaves). The most mature tea leaves fermented to a small degree contained relatively the highest PAH levels among all four tested tea types. Relatively low PAH transfer rates into tea infusions and limited volumes of the consumed tea keep the risks associated with PAH dietary intake at a safely low level. The worst-case scenario dietary intake values were 7.62/0.82/0.097 ng kg -1 b.w. day -1 (estimated on the basis of the maximum found concentrations 696/113/23 µg kg -1 and maximum observed transfer rates 24/16/9%) for ∑28PAH/∑PAH4/B[a]P, respectively. MOE values calculated using the above worst case estimates exceeded 700,000 and 400,000 (BMDL 10 0.07 and 0.34 mg kg -1 b.w. day -1 ) for B[a]P and PAH4, respectively. Both B[a]P and PAH4 concentrations may be used as indicators of total PAH concentration in tea leaves; PAH4 slightly better fits low molecular weight PAHs. Several correlations between various PAHs/groups of PAHs have been identified, the strongest one (R 2 = 0.92) between PAH4 and EU PAH 15+1.

  4. Preparation and Mechanical Properties of Aligned Discontinuous Carbon Fiber Composites

    OpenAIRE

    DENG Hua; GAO Junpeng; BAO Jianwen

    2018-01-01

    Aligned discontinuous carbon fiber composites were fabricated from aligned discontinuous carbon fiber prepreg, which was prepared from continuous carbon fiber prepreg via mechanical high-frequency cutting. The internal quality and mechanical properties were characterized and compared with continuous carbon fiber composites. The results show that the internal quality of the aligned discontinuous carbon fiber composites is fine and the mechanical properties have high retention rate after the fi...

  5. Polish reference material: soya bean flour (INCT-SBF-4) for inorganic trace analysis - preparation and certification

    International Nuclear Information System (INIS)

    Polkowska-Motrenko, H.; Dybczynski, R.; Chajduk, E.; Danko, B.; Kulisa, K.; Samczynski, Z.; Sypula, M.; Szopa, Z.

    2006-01-01

    Preparation, examination and certification of the new matrix reference material of biological origin: Soya Bean Flour (INCT-SBF-4) is described. The material was prepared from soya bean grown in India, not genetically modified. After milling, the material was sieved through the 150 mm nylon sieves and stored in a polyethylene (PE) bag. Approximately 50 kg of sieved soya bean flour was collected. Examination by optical microscopy revealed that Martin's diameter of over 90% of particles was below 50 mm. The whole lot of soya bean flour was then homogenized by mixing for 20 hours in a 110 dm 3 PE drum rotated in three directions. Preliminary homogeneity testing by X-ray fluorescence (XRF) method and final checking of homogeneity by neutron activation analysis (NAA) after distribution of the material into containers revealed, that it is sufficiently homogeneous at least for a sample size ≥ 100 mg. In order to assure the long-term stability, all containers with INCT-SBF-4 were sterilized by electron beam radiation. Long-term stability was checked by analyzing concentrations of selected elements in the material stored in the air-conditioned room at 20 o C. Short-term stability was examined by the determination of concentrations of the selected elements in the bottle stored in the CO 2 incubator at 37 o C. The material was certified on the basis of a worldwide interlaboratory comparison, in which 92 laboratories from 19 countries participated providing 1107 laboratory averages (4873 individual determinations) for 58 elements. A method of data evaluation leading to assignment of certified values was the same as that used previously in the Laboratory of the Department of Analytical Chemistry, Institute of Nuclear Chemistry and Technology. The results for a few elements were obtained by definitive methods developed in the Laboratory and used to support the certification process. Analytical uncertainties and stability uncertainties were quantified to arrive at combined

  6. Metallographic preparation of Zr-2.5Nb pressure tube material for examination of inclusions

    International Nuclear Information System (INIS)

    Lockley, A.J.

    1994-11-01

    The traditional final polish of Zr-2.5Nb alloy comprises an attack polish that contains a 0.05 μm alumina or fly-ash slurry with dilute hydrofluoric acid. This polish preferentially etches the material adjacent to the inclusions and distorts or removes the inclusions. A final polish has been developed that uses a caustic alumina slurry to produce a chemical-mechanical polish that keeps the inclusions intact. This preparation is reproducible, suitable for automation, and retains smaller inclusions. (author). 2 refs., 5 figs

  7. States and state-preparing procedures in quantum mechanics

    International Nuclear Information System (INIS)

    Benioff, P.A.; Ekstein, Hans

    D'Espagnat and others have shown that different preparation procedures that mix systems prepared in unequivalent states and objectively different, are nevertheless assigned the same state. This unpalatable result follows from the usual interpretative rules of quantum mechanics. It is shown here that this result is incompatible with the strengthened interpretative rules (requiring randomness of the measurement outcome sequence) recently proposed. Thus, the randomness requirement restores reasonableness

  8. Audit Committee Practice in the Polish Listed Stock Companies. Present Situation and Development Perspectives

    Directory of Open Access Journals (Sweden)

    Piotr Szczepankowski

    2012-06-01

    Full Text Available The audit committee is one of the parts of corporate governance mechanism, which is understood as the relationship between corporate managers, directors and the providers of equity, people and institutions who save and invest their capital to earn the return. This study presents survey research results of audit committee activity in Polish public stock companies quoted on the Warsaw Stock Exchange (WSE. The purpose of this paper is to present the audit committee practice in Poland after 2009. The paper shows that the audit committee practice is still the most problematic issue of transitional Polish corporate governance rules. The survey has shown that the corporate needs and its implementation, and communication with listed companies leave a lot of room for improvement. The paper is based on the documents prepared in 2010 by PricewaterhouseCoopers, the Polish Association of Listed Companies and the Polish Institute of Directors.

  9. Mechanical bowel preparation in elective open colon surgery

    NARCIS (Netherlands)

    Fa-Si-Oen, Patrick Regnier

    2006-01-01

    Mechanical bowel preparation is a long standing practice in elective open colon surgery dating from the 1970's. It has always been believed to reduce the rate of postoperative complications in the form of anastomotic leakage and wound infection. In this thesis we broadly and thoroughly examine the

  10. Mécanisme de l'usure par polissage des cylindres de moteurs diesel Bore Polishing Wear Mechanism in Diesel Engine Cylinders

    Directory of Open Access Journals (Sweden)

    Fayard J. C.

    2006-11-01

    particulier, l'usure des segments ainsi que les débits de gaz de soufflage, sont plus faibles qu'avec une chemise normale. Enfin, le mécanisme de l'usure par polissage par abrasion douce à deux et à trois corps est parfaitement confirmé par une exploration micrographique et une microanalyse des surfaces polies. A fast and economical method for evaluating lubricants and fuels in relation to the bore polishing wear of super charged diesel-engine cylinders has been developed using a single-cylinder laboratory engine within the framework of an Société Nationale Elf Aquitaine - Institut Français du Pétrole (SNEA-lFP research agreement. This method bears the reference IFP-UP-4/80.It also serves to evaluate the deposit-forming and sticking tendency, ring wear and the oil-consumption tendency of lubricants. It is in good correlation with the CEC-Ford Tornado test and makes an excellent discrimination between the Coordinating European Council (CEC reference cils RL 47 and RL 48. The method is used for investigating the bore polishingwear mechanism by searching for the influence exerted by the principal parameters: (a Composition of the lubricant: the phenomenon is influenced by the base oil and its viscosity, by the amount of polymers improving the viscosity index and especially by the choice of detergent additives. As a first approximation and for homogeneous oil familles, polishing wear increases when the thermal stability of the oil decreases. (b Engine running: polishing increases very fart with the engine load after a certain threshold, and its evolution in time as observed by endoscopic rating shows a characteristic S shape as polishing begins on the thrust side and at the top of the cylinder. (c Composition of the fuel: the increase in the sulfur content of diesel fuel considerably decreases polishing wear caused by an oil reputed to be poorfrom this standpoint but has no effect on a goodoil. (d Surface finish of the cylinder: prepolishing the liner by extremely fine

  11. Mechanical Conversion for High-Throughput TEM Sample Preparation

    International Nuclear Information System (INIS)

    Kendrick, Anthony B; Moore, Thomas M; Zaykova-Feldman, Lyudmila

    2006-01-01

    This paper presents a novel method of direct mechanical conversion from lift-out sample to TEM sample holder. The lift-out sample is prepared in the FIB using the in-situ liftout Total Release TM method. The mechanical conversion is conducted using a mechanical press and one of a variety of TEM coupons, including coupons for both top-side and back-side thinning. The press joins a probe tip point with attached TEM sample to the sample coupon and separates the complete assembly as a 3mm diameter TEM grid, compatible with commercially available TEM sample holder rods. This mechanical conversion process lends itself well to the high through-put requirements of in-line process control and to materials characterization labs where instrument utilization and sample security are critically important

  12. Functional Median Polish

    KAUST Repository

    Sun, Ying; Genton, Marc G.

    2012-01-01

    polish is demonstrated by comparing its performance with the traditional functional ANOVA fitted by means under different outlier models in simulation studies. The functional median polish is illustrated on various applications in climate science

  13. Evidence for two concurrent inhibitory mechanisms during response preparation

    Science.gov (United States)

    Duque, Julie; Lew, David; Mazzocchio, Riccardo; Olivier, Etienne; Ivry, Richard B.

    2010-01-01

    Inhibitory mechanisms are critically involved in goal-directed behaviors. To gain further insight into how such mechanisms shape motor representations during response preparation, motor evoked potentials (MEPs) elicited by transcranial magnetic stimulation (TMS) and H-reflexes were recorded from left hand muscles during choice reaction time tasks. The imperative signal, which indicated the required response, was always preceded by a preparatory cue. During the post-cue delay period, left MEPs were suppressed when the left hand had been cued for the forthcoming response, suggestive of a form of inhibition specifically directed at selected response representations. H-reflexes were also suppressed on these trials, indicating that the effects of this inhibition extend to spinal circuits. In addition, left MEPs were suppressed when the right hand was cued, but only when left hand movements were a possible response option before the onset of the cue. Notably, left hand H-reflexes were not modulated on these trials, consistent with a cortical locus of inhibition that lowers the activation of task-relevant, but non-selected responses. These results suggest the concurrent operation of two inhibitory mechanisms during response preparation: one decreases the activation of selected responses at the spinal level, helping to control when selected movements should be initiated by preventing their premature release; a second, upstream mechanism helps to determine what response to make during a competitive selection process. PMID:20220014

  14. Hydroxyapatite nanocrystals: Simple preparation, characterization and formation mechanism

    International Nuclear Information System (INIS)

    Mohandes, Fatemeh; Salavati-Niasari, Masoud; Fathi, Mohammadhossein; Fereshteh, Zeinab

    2014-01-01

    Crystalline hydroxyapatite (HAP) nanoparticles and nanorods have been successfully synthesized via a simple precipitation method. To control the shape and particle size of HAP nanocrystals, coordination ligands derived from 2-hydroxy-1-naphthaldehyde were first prepared, characterized by Fourier transform infrared (FT-IR) and proton nuclear magnetic resonance ( 1 H-NMR) spectroscopies, and finally applied in the synthesis process of HAP. On the other hand, the HAP nanocrystals were also characterized by several techniques including powder X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM). According to the FE-SEM and TEM micrographs, it was found that the morphology and crystallinity of the HAP powders depended on the coordination mode of the ligands. - Highlights: • HAP nanobundles and nanoparticles have been prepared by a precipitation method. • Morphologies of HAP nanocrystals were controlled by different coordination ligands. • The formation mechanism of hydroxyapatite nanocrystals was also considered

  15. Hydroxyapatite nanocrystals: Simple preparation, characterization and formation mechanism

    Energy Technology Data Exchange (ETDEWEB)

    Mohandes, Fatemeh [Department of Inorganic Chemistry, Faculty of Chemistry, University of Kashan, Kashan, P. O. Box. 87317-51167, Islamic Republic of Iran (Iran, Islamic Republic of); Salavati-Niasari, Masoud, E-mail: salavati@kashanu.ac.ir [Department of Inorganic Chemistry, Faculty of Chemistry, University of Kashan, Kashan, P. O. Box. 87317-51167, Islamic Republic of Iran (Iran, Islamic Republic of); Institute of Nano Science and Nano Technology, University of Kashan, Kashan, P. O. Box 87317-51167, Islamic Republic of Iran (Iran, Islamic Republic of); Fathi, Mohammadhossein [Biomaterials Research Group, Department of Materials Engineering, Isfahan University of Technology, Isfahan 8415683111, Islamic Republic of Iran (Iran, Islamic Republic of); Dental Materials Research Center, Isfahan University of Medical Sciences, Isfahan, Islamic Republic of Iran (Iran, Islamic Republic of); Fereshteh, Zeinab [Biomaterials Research Group, Department of Materials Engineering, Isfahan University of Technology, Isfahan 8415683111, Islamic Republic of Iran (Iran, Islamic Republic of)

    2014-12-01

    Crystalline hydroxyapatite (HAP) nanoparticles and nanorods have been successfully synthesized via a simple precipitation method. To control the shape and particle size of HAP nanocrystals, coordination ligands derived from 2-hydroxy-1-naphthaldehyde were first prepared, characterized by Fourier transform infrared (FT-IR) and proton nuclear magnetic resonance ({sup 1}H-NMR) spectroscopies, and finally applied in the synthesis process of HAP. On the other hand, the HAP nanocrystals were also characterized by several techniques including powder X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM). According to the FE-SEM and TEM micrographs, it was found that the morphology and crystallinity of the HAP powders depended on the coordination mode of the ligands. - Highlights: • HAP nanobundles and nanoparticles have been prepared by a precipitation method. • Morphologies of HAP nanocrystals were controlled by different coordination ligands. • The formation mechanism of hydroxyapatite nanocrystals was also considered.

  16. Cancer morbidity among polishers.

    Science.gov (United States)

    Järvholm, B; Thiringer, G; Axelson, O

    1982-01-01

    The mortality pattern among 86 men was determined to investigate the possible hazards of polishing steel. The men had polished steel with polishing paste for at least five years. The polishing pastes had contained tallow, beeswax, carnauba wax, alundum, carborundum, ferric oxide, and chalk. A total of 18 men had died compared with 13.3 expected. Four had died of stomach cancer compared with 0.44 expected (p less than 0.005). The mortality for other causes of death was not increased. The study does not permit any definite conclusion but indicates a possible cancer hazard among polishers. PMID:7066237

  17. Evaluation of the effect of polishing on flexural strength of feldspathic porcelain and its comparison with autoglazing and over glazing

    Directory of Open Access Journals (Sweden)

    Jalali H.

    2005-06-01

    Full Text Available Statement of Problem: Ceramic restorations are popular because they can provide the most natural replacement for teeth. However, the brittleness of ceramics is a primary disadvantage. There are various methods for strengthening ceramics such as metal framework, ceramic cores, and surface strengthening mechanisms through glazing, work hardening and ion exchange. Purpose: The purpose of this study was to evaluate the effect of polish on flexural strength of feldspathic porcelain and to compare it with overglaze and autoglaze. Materials and Methods: In this experimental study, one brand of feldspathic porcelain (colorlogic, Ceramco was used and forty bars (25×6×3 mm were prepared according to ISO 6872 and ADA No. 69. The specimens were randomly divided into four groups: overglazed, auto glazed, fine polish and coarse polish (clinic polish. Flexural strength of each specimen was determined by three point bending test (Universal Testing Machine, Zwick 1494, Germany. Collected data was analyzed by ANOVA and post-hoc test with P<0.05 as the limit of significance. Results: A significant difference was observed among the studied groups (P<0.0001. According to post-hoc test, flexural strength in overglaze and fine polish group were significantly stronger than clinic polish and autoglaze group (P<0.001. Although the mean value for overglazed group was higher than fine polish group, this was not statistically significant (P=0.9. Also no statistical difference was seen between autoglazed and coarse polish group (P=0.2. Conclusion: Based on the findings of this study, flexural strength achieved by fine polish (used in this study can compete with overglazing the feldespathic porcelains. It also can be concluded that a final finishing procedure that involves fine polishing may be preferred to simple staining followed by self-glazing.

  18. Electrolytic polishing system for space age materials

    International Nuclear Information System (INIS)

    Coons, W.C.; Iosty, L.R.

    1976-01-01

    A simple electrolytic polishing technique was developed for preparing Cr, Co, Hf, Mo, Ni, Re, Ti, V, Zr, and their alloys for structural analysis on the optical microscope. The base electrolyte contains 5g ZnCl 2 and 15g AlCl 3 . 6H 2 O in 200 ml methyl alcohol, plus an amount of H 2 SO 4 depending on the metal being polished. Five etchants are listed

  19. Mechanical properties of nanocrystalline palladium prepared by magnetron sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Castrup, Anna; Hahn, Horst [Forschungszentrum Karlsruhe (Germany); Technical University of Darmstadt (Germany); Scherer, Torsten; Ivanisenko, Yulia; Choi, In-Suk; Kraft, Oliver [Forschungszentrum Karlsruhe (Germany)

    2009-07-01

    Nanocrystalline metals and alloys with grain sizes well below 100 nm often demonstrate unique deformation behaviour and therefore attract a great interest in material science. The understanding of deformation mechanisms operating in nanocrystalline materials is important to predict their mechanical properties. In the present study Pd films of 1{mu}m thickness were prepared using UHV rf magnetron sputtering on dog bone shaped Kapton substrates and on Si/SiO2 wafers. The films were sputtered using multilayer technology with an individual layer thickness of 10 nm. This resulted in grain sizes of about 20 nm. Initial microstructure and texture were characterized using conventional XRD measurements and transmission electron microscopy (TEM) in both cross section- and plane view. The mechanical properties were investigated using tensile testing and nanoindentation at several strain rates. An increased hardness and strength as compared to coarse grained Pd was observed, as well as high strain rate sensitivity. The microstructure in the gauge section after tensile testing was again analyzed using TEM in order to reveal signatures of deformation mechanisms like dislocation motion or twinning.

  20. Polishing of silicon based advanced ceramics

    Science.gov (United States)

    Klocke, Fritz; Dambon, Olaf; Zunke, Richard; Waechter, D.

    2009-05-01

    Silicon based advanced ceramics show advantages in comparison to other materials due to their extreme hardness, wear and creep resistance, low density and low coefficient of thermal expansion. As a matter of course, machining requires high efforts. In order to reach demanded low roughness for optical or tribological applications a defect free surface is indispensable. In this paper, polishing of silicon nitride and silicon carbide is investigated. The objective is to elaborate scientific understanding of the process interactions. Based on this knowledge, the optimization of removal rate, surface quality and form accuracy can be realized. For this purpose, fundamental investigations of polishing silicon based ceramics are undertaken and evaluated. Former scientific publications discuss removal mechanisms and wear behavior, but the scientific insight is mainly based on investigations in grinding and lapping. The removal mechanisms in polishing are not fully understood due to complexity of interactions. The role of, e.g., process parameters, slurry and abrasives, and their influence on the output parameters is still uncertain. Extensive technological investigations demonstrate the influence of the polishing system and the machining parameters on the stability and the reproducibility. It is shown that the interactions between the advanced ceramics and the polishing systems is of great relevance. Depending on the kind of slurry and polishing agent the material removal mechanisms differ. The observed effects can be explained by dominating mechanical or chemo-mechanical removal mechanisms. Therefore, hypotheses to state adequate explanations are presented and validated by advanced metrology devices, such as SEM, AFM and TEM.

  1. [Lysenkoism in Polish botany].

    Science.gov (United States)

    Köhler, Piotr

    2008-01-01

    Lysenkoism in Poland was never an autonomous phenomenon. The whole array of reasons for which it appeared in Polish science would require a separate study--here it only needs to be pointed out that the major reasons included terror on the part of the security service, lawlessness, the ubiquitous atmosphere of intimidation and terror, censorship, the diminishing sphere of civil liberties, political show trials, propaganda and denunciations. An important role in facilitating the introduction of Lysenkoism was played also by the reorganization of science after World War Two, the isolation of Polish science from science in the West, as well as the damage it had suffered during the war. At first, Lysenkoism was promoted in Poland by a small group of enthusiastic and uncritical proponents. A overview of the events connected with the ten years of Lysenkoism in Poland (end of 1948--beginning of 1958) shows a two-tier picture of how the 'idea' was propagated. The first tier consisted in the activities of the Association of Marxist Naturalists [Koło Przyrodników-Marksistów], which it engaged in since the end of 1948. The Association was later transformed into a Union of Marxist Naturalists, and this in turn merged, in 1952, with the Copernican Society of Polish Naturalists [Polskie Towarzystwo Przyrodników im. Kopernika]. It was that society which promoted Lysenkoism longest, until the end of 1956. The propaganda and training activities of the circle and the society prepared ground for analogous activities of the newly formed Polish Academy of Science (PAN), which--since its very establishment in 1952--engaged in promoting Lysenkoism through its Second Division. These activities were aimed at naturalists, initially at those who were prominent scientists (eg. the conference at Kuźnice, 1950/1951), and then at those who were only starting their academic career (including national courses in new biology at Dziwnów, 1952, or Kortowo, 1953 and 1955). The end to promoting

  2. Preparation of Mn-Zn nanoferrite by mechanical alloying

    International Nuclear Information System (INIS)

    Nasresfahani, M.

    2007-01-01

    Full text: In this research Mn-Zn nanoferrite (Mn x Zn 1-x Fe 2 O 4 ;X=0.3,0.5,0.7)were prepared by mechanical alloying of a mixture of 2 single phase ferrites, MnFe 2 O 4 and ZnFe 2 O 4 . First, ZnFe 2 O 4 and MnFe 2 O 4 were obtained by conventional ceramic technique. In this technique a mixture of related raw materials(ZnO and MnO 2 from merck company and Fe 2 O 3 domestic source) was first mixed and calcined at 1100 C for 3h in air. The starting materials used to prepare Mn-Zn nanoferrite were MnFe 2 O 4 and ZnFe 2 O 4 mixed in the ratio appropriate for the reaction: xMnFe 2 O 4+(1-x) ZnFe 2 O 4 MnxZn 1-x Fe 2 O 4 and milled at different times in SPEX8000M mixer/mill. XRD investigations was used to study the phase formation of the as-milled mixed ferrite. Using XRD patterns and Scherrer's formula, mean crystallite size of the single phase samples were calculated and were in the 10-20 nm. Saturation magnetization(Ms) of the powders was measured at room temperature by a very sensitive home made permeameter. The measured Ms values show that they are smaller than the Ms values associated with the same compound prepared by conventional ceramic technique. The decrease is due to the surface effect in nanoparticles, which can be explained on core-sell model. (authors)

  3. Polish Conference on the Theory of Machines and Mechanisms, 11th, Zakopane, Poland, Apr. 27-30, 1987, Proceedings

    Energy Technology Data Exchange (ETDEWEB)

    1987-01-01

    The conference presents papers on the diagnostic classification of machinery conditions and their interpretation, the detection of parameter changes in a mechanical nonlinear rotational system, microcomputer-aided teaching of the fundamentals of machine steering, the basic functions of expert systems, and the basic requirements of a CAD system for designing robotized stands. Consideration is also given to the determination of the position function in link mechanisms, the application of the finite element method to the study of the human skeletal system, and a method of suboptimal decentralized control in robotics. Other topics include the principles and techniques of pragmatic simulation, polyoptimal synthesis, and bending vibrations of a shaft with thin disks.

  4. Health Information in Polish (polski)

    Science.gov (United States)

    ... Tools You Are Here: Home → Multiple Languages → Polish (polski) URL of this page: https://medlineplus.gov/languages/polish.html Health Information in Polish (polski) To use the sharing features on this page, ...

  5. Processing, Mechanical and Optical Properties of Additive-Free ZrC Ceramics Prepared by Spark Plasma Sintering

    Directory of Open Access Journals (Sweden)

    Clara Musa

    2016-06-01

    Full Text Available In the present study, nearly fully dense monolithic ZrC samples are produced and broadly characterized from microstructural, mechanical and optical points of view. Specifically, 98% dense products are obtained by Spark Plasma Sintering (SPS after 20 min dwell time at 1850 °C starting from powders preliminarily prepared by Self-propagating High-temperature Synthesis (SHS followed by 20 min ball milling. A prolonged mechanical treatment up to 2 h of SHS powders does not lead to appreciable benefits. Vickers hardness of the resulting samples (17.5 ± 0.4 GPa is reasonably good for monolithic ceramics, but the mechanical strength (about 250 MPa up to 1000 °C could be further improved by suitable optimization of the starting powder characteristics. The very smoothly polished ZrC specimen subjected to optical measurements displays high absorption in the visible-near infrared region and low thermal emittance at longer wavelengths. Moreover, the sample exhibits goodspectral selectivity (2.1–2.4 in the 1000–1400 K temperature range. These preliminary results suggest that ZrC ceramics produced through the two-step SHS/SPS processing route can be considered as attractive reference materials for the development of innovative solar energy absorbers.

  6. STUDY OF POLISHING AISI 316L WITH STRUCTURED ABRASIVE

    Directory of Open Access Journals (Sweden)

    François GOOSSENS

    2015-05-01

    Full Text Available Finishing process like polishing is usually used to obtain high quality mechanical surface characteristics such as texture and roughness. These operations are mainly handmade and need highly trained operators thus limiting their repeatability and profitability. To optimize the industrialization of the polishing process, it is therefore necessary to modelize the process to built efficient parameter database. The aim of this study is to characterise the polishing of 316L stainless steel with structured abrasive belts. The geometric data of the belts are given, and we then propose a model to determine material removal. An experimental test bench is set up to test this model and characterise the polishing process in terms of forces. It produces samples for different polishing conditions. The different polished surfaces are then analyzed thanks to the roughness and the wettability. Using experimental designs, we are able to validate the proposed model and identify the parameters that influence a polishing operation.

  7. Polish Cartographical Review

    Directory of Open Access Journals (Sweden)

    Nedjeljko Frančula

    2017-07-01

    Full Text Available The Polish Cartographical Review (PCR journal has been published in English four times a year since 2015. The journal is in open access and it is published by De Gruyter Open. It is edited by Polish scientists in collaboration with international experts.

  8. Morphometric, densitometric and mechanical properties of mandibular deciduous teeth in 5-month-old Polish Merino sheep.

    Science.gov (United States)

    Tatara, Marcin R; Szabelska, Anna; Krupski, Witold; Tymczyna, Barbara; Luszczewska-Sierakowska, Iwona; Bieniaś, Jarosław; Ostapiuk, Monika

    2014-02-19

    Caries, enamel hypoplasia, molar incisor hipomineralization, amylogenesis imperfecta, dentine dysplasia, hypophosphatasia and other dental disorders lead to tooth mineralization disturbances and structural abnormalities, decreasing masticatory organ functions. Dental disorders in sheep can lead to premature slaughter before they have attained final stage of their reproductive life and induce economic loss due to high flock replacement costs. Growth rate, health status and meat quality of sheep depends on tooth properties and quality determining in large extent efficiency of the masticatory apparatus and initial food break up. Considering lack of basic anatomical and physiological data on teeth properties in sheep, the aim of the study was to evaluate morphometric, densitometric and mechanical traits of deciduous mandibular incisor, canine and the second premolar obtained at the slaughter age of 5 months of life. The obtained results have shown the highest values of weight, total tooth volume, enamel volume and dentine volume in second premolar. Morphometric and mechanical parameters of incisors reached the highest values in first incisor and decreased gradually in second and third incisor, and in canine. Densitometric measurements have not revealed significant differences of the volumetric tooth mineral density in hard dental tissues between the investigated teeth. In conclusion, proposed methodological approach is noninvasive since the deciduous teeth undergo physiological replacement with permanent teeth. Deciduous teeth can be easy collected for analyses from large animal population and may reflect mineral status and metabolism resulting from postnatal growth and development of the whole flock. In individual cases, evaluation of properties of deciduous teeth may serve for breeding selection and further reproduction of sheep possessing favorable traits of teeth and better masticatory system functions.

  9. Assessment of the radiation risk following from exploitation of Polish brown coals. Part 1. Brown coal in Polish industry; preparation of the method of determining the concentrations of main natural radioisotopes appearing in brown coal and its combustion products

    International Nuclear Information System (INIS)

    Jasinska, M.; Niewiadomski, T.; Schwabenthan, J.

    1982-01-01

    Poland is rich in deposits of brown coal applicable for large-scale industry. These deposits are estimated at about 13.5.10 9 tons. In the near future, one-half of the electric power produced in Poland will be generated by power plants using brown coal. As a result, the yearly burden of the environment in Poland will amount to about 15.10 6 tons of ashes and slag, and about 0.79.10 6 tons of fly ash emitted into the atmosphere. Concentrations of radioactive elements in wastes following from the use of brown coal may in some cases be as much as 12 times higher that occuring from combustion products of lignite coal. Distribution of these wastes to the environment affects the population, through inhalation of fly-ashes, consumption of radioactively contaminated products and through living in dwellings constructed of building materials produced using industrial wastes. In order to determine the concentrations of 226 Ra, 232 Th and 40 K in brown coal and in products of its combustion, the method of identifying these elements through gamma-spectrometry has been prepared. Concentrations of 210 Pb and 210 Po will be determined using the method of electrodeposition on metallic silver, which has been tested in the laboratory. (author)

  10. Nanoscale wedge polishing of superconducting thin films-an easy way to obtain depth dependent information by surface analysis techniques

    International Nuclear Information System (INIS)

    Shapoval, T; Engel, S; Gruendlich, M; Meier, D; Backen, E; Neu, V; Holzapfel, B; Schultz, L

    2008-01-01

    A mechanical wedge polishing procedure that offers a simple, cost-effective and rapid way to look into the depth of a thin film with different surface-sensitive scanning techniques has been developed. As an example of its wide applicability, this method was utilized for the investigation of two differently prepared superconducting YBa 2 Cu 3 O 7-δ thin films: an Hf-doped film prepared by chemical solution deposition and an undoped film grown by pulsed laser deposition. Upon polishing, the roughness of the samples was reduced to less than 5 nm (peak-to-valley) without influencing the superconducting properties of the films. Thus, nanoscale polishing opens up a unique possibility for microscopic studies with various surface-sensitive techniques. We demonstrate the successful imaging of flux lines by low temperature magnetic force microscopy after polishing a formerly rough as-prepared film. By applying the wedge polishing procedure to the Hf-doped sample, high resolution electron backscattering diffraction investigations reveal the homogeneous distribution of non-superconducting BaHfO 3 nanoparticles in the whole volume of the film

  11. Solid state amorphisation in binary systems prepared by mechanical alloying

    International Nuclear Information System (INIS)

    Gonzalez, G.; Sagarzazu, A.; Bonyuet, D.; D'Angelo, L.; Villalba, R.

    2009-01-01

    In the present work a detailed study of amorphisation in different systems prepared by mechanical alloying under the same experimental conditions was carried out, milling up to 50 and 100 h in some cases. The systems studied were: AlTi, AlNi, AlFe, FeNi, FeCo, NiMo, NiW, NiCo, MoW, CoMo. These systems were chosen to study the effect of Al-transition metal, transition metal-transition metal and also systems with large and small negative heat of mixing, different and similar crystal structures, atomic sizes and diffusion coefficients. Calculations based on the Miedema model for alloy formation and amorphisation on all the alloys studied were performed. The experimental results from X-ray diffraction and transmission electron microscopy showed that the systems based on Fe (FeNi, FeCo and FeAl) did not amorphised, even after milling for 100 h, and formed a stable solid solution with a nanometric grain size of 7 nm. The systems NiMo, NiW, MoW and CoMo (systems with small negative heat of mixing), showed amorphisation after 50 h of milling. NiAl and TiAl form an intermediate amorphous phase after around 20 h of milling and with further milling they recrystallize into a fcc solid solution. Agreement between the theoretical calculations based on the Miedema model and the experimental results was found in most of the systems.

  12. Effects of polishing procedures on color stability of composite resins

    Directory of Open Access Journals (Sweden)

    Ahmet Umut Güler

    2009-04-01

    Full Text Available The purpose of this study was to investigate the effect of different polishing methods on color stability of posterior, universal and nanohybrid composite resin restorative materials upon exposure to a staining agent. Twenty-five specimens were prepared for each of 5 different composite resins (Filtek Z250, Filtek P60, Quadrant LC, Grandio and Filtek Supreme. Specimens were divided into 5 groups and different polishing procedures, including polishing discs (Pd, polishing discs then diamond polishing paste (PdP, polishing discs then a liquid polishing system (Biscover (PdB, and combinations of these (PdPB were used. Unpolished specimens served as the control (C. The specimens were stored for 48 h in a coffee solution. The color of all specimens was measured before and after exposure with a colorimeter, and total color change (DE* were calculated. The data were analyzed with a two-way ANOVA and the means were compared by Tukey HSD test (a=0.05. The lowest color difference was observed in the groups PdP and C, while the highest color difference was observed in PdPB, and PdB. When comparing the five different restorative materials, no significant difference was observed between FiltekP60 and FiltekZ250, and these materials demonstrated significantly less color change than Quadrant LC and the nanohybrid materials (Grandio, Filtek Supreme. The posterior (Filtek P60 and universal (Filtek Z250 composite resin restorative materials, which do not contain tetraethyleneglycol dimethacrylate (TEGDMA, were found to be less stainable than the nanohybrid (Grandio, Filtek Supreme and universal (Quadrant LC composite resins, which contain TEGDMA. The use of diamond polishing paste after polishing with polishing discs significantly decreased staining when compared to the groups that used polishing discs alone, for all restorative materials tested. The highest color change values were obtained for the specimens that were polished with the Biscover liquid polish

  13. Tribological approach to study polishing of road surface under traffic

    OpenAIRE

    KANE, Malal; DO, Minh Tan

    2007-01-01

    The polishing phenomenon of road pavements under the vehicle traffic constitutes the main mechanism inherent to the loss of skid resistance over time. A better understanding of this phenomenon would allow an improvement of road safety. This study comprises a review of laboratory test and a model simulating the polishing of road surfaces. The laboratory test uses a polishing machine so called 'Wehner-Schulze' which can reproduce the evolution of the road texture from specimens taken directly f...

  14. Preparation and mechanical properties of edible rapeseed protein films.

    Science.gov (United States)

    Jang, Sung-Ae; Lim, Geum-Ok; Song, Kyung Bin

    2011-03-01

    Edible films were manufactured from rapeseed oil extraction residues. To prepare rapeseed protein (RP) films, various concentrations of plasticizers and emulsifiers were incorporated into the preparation of a film-forming solution. The optimal conditions for the preparation of the RP film were 2% sorbitol/0.5% sucrose as plasticizer and 1.5% polysorbate 20 as an emulsifier. In addition, RP blend films were prepared. Gelidium corneum or gelatin was added to improve the physical properties of the RP film, and the highest tensile strength value of the films was 53.45 MPa for the 3% RP/4% gelatin film. Our results suggest that the RP-gelatin blend film is suitable for applications in food packaging. Edible RP films prepared in the present investigation can be applied in food packaging.

  15. Polish polar research (outline

    Directory of Open Access Journals (Sweden)

    Krzysztof Ludwik Birkenmajer

    2017-12-01

    Full Text Available The article describes Polish research and discoveries in the Arctic and the Antarctic since the 19th century. The author is a geologist and since 1956 has been engaged in scientific field research on Spitsbergen, Greenland and Antarctica (23 expeditions. For many years chairman of the Committee on Polar Research of the Polish Academy of Sciences, he is now its Honorary Chairman.

  16. Elastic emission polishing

    Energy Technology Data Exchange (ETDEWEB)

    Loewenthal, M.; Loseke, K.; Dow, T.A.; Scattergood, R.O.

    1988-12-01

    Elastic emission polishing, also called elastic emission machining (EEM), is a process where a stream of abrasive slurry is used to remove material from a substrate and produce damage free surfaces with controlled surface form. It is a noncontacting method utilizing a thick elasto-hydrodynamic film formed between a soft rotating ball and the workpiece to control the flow of the abrasive. An apparatus was built in the Center, which consists of a stationary spindle, a two-axis table for the workpiece, and a pump to circulate the working fluid. The process is controlled by a programmable computer numerical controller (CNC), which presently can operate the spindle speed and movement of the workpiece in one axis only. This apparatus has been used to determine material removal rates on different material samples as a function of time, utilizing zirconium oxide (ZrO{sub 2}) particles suspended in distilled water as the working fluid. By continuing a study of removal rates the process should become predictable, and thus create a new, effective, yet simple tool for ultra-precision mechanical machining of surfaces.

  17. Novel EBSD preparation method for Cu/Sn microbumps using a focused ion beam

    International Nuclear Information System (INIS)

    Liu, Tao-Chi; Chen, Chih; Chiu, Kuo-Jung; Lin, Han-Wen; Kuo, Jui-Chao

    2012-01-01

    We proposed a novel technique developed from focused ion beam (FIB) polishing for sample preparation of electron backscatter diffraction (EBSD) measurement. A low-angle incident gallium ion beam with a high acceleration voltage of 30 kV was used to eliminate the surface roughness of cross-sectioned microbumps resulting from mechanical polishing. This work demonstrates the application of the FIB polishing technique to solders for a high-quality sample preparation for EBSD measurement after mechanical polishing. - Highlights: ► The novel FIB technique of sample preparation is fast, effective and low-cost. ► It can enhance the process precision to the specific area of the sample. ► It is convenient for analyzing the metallurgy of the microbump in 3DIC packaging. ► The EBSD image quality can be enhanced by just using a common FIB instrument.

  18. Impact of mechanical bowel preparation in elective colorectal surgery: A meta-analysis.

    Science.gov (United States)

    Rollins, Katie E; Javanmard-Emamghissi, Hannah; Lobo, Dileep N

    2018-01-28

    To analyse the effect of mechanical bowel preparation vs no mechanical bowel preparation on outcome in patients undergoing elective colorectal surgery. Meta-analysis of randomised controlled trials and observational studies comparing adult patients receiving mechanical bowel preparation with those receiving no mechanical bowel preparation, subdivided into those receiving a single rectal enema and those who received no preparation at all prior to elective colorectal surgery. A total of 36 studies (23 randomised controlled trials and 13 observational studies) including 21568 patients undergoing elective colorectal surgery were included. When all studies were considered, mechanical bowel preparation was not associated with any significant difference in anastomotic leak rates (OR = 0.90, 95%CI: 0.74 to 1.10, P = 0.32), surgical site infection (OR = 0.99, 95%CI: 0.80 to 1.24, P = 0.96), intra-abdominal collection (OR = 0.86, 95%CI: 0.63 to 1.17, P = 0.34), mortality (OR = 0.85, 95%CI: 0.57 to 1.27, P = 0.43), reoperation (OR = 0.91, 95%CI: 0.75 to 1.12, P = 0.38) or hospital length of stay (overall mean difference 0.11 d, 95%CI: -0.51 to 0.73, P = 0.72), when compared with no mechanical bowel preparation, nor when evidence from just randomized controlled trials was analysed. A sub-analysis of mechanical bowel preparation vs absolutely no preparation or a single rectal enema similarly revealed no differences in clinical outcome measures. In the most comprehensive meta-analysis of mechanical bowel preparation in elective colorectal surgery to date, this study has suggested that the use of mechanical bowel preparation does not affect the incidence of postoperative complications when compared with no preparation. Hence, mechanical bowel preparation should not be administered routinely prior to elective colorectal surgery.

  19. Chemical mechanical polisher technology for 300mm/0.18-0.13{mu}m semiconductor devices; 300mm/0.18-0.-0.13{mu}m sedai no CMP gijutsu

    Energy Technology Data Exchange (ETDEWEB)

    Tsujimura, M.; Kobayashi, F. [Ebara Corp., Tokyo (Japan)

    1998-10-20

    Described herein are problems involved in, and development points and measures for chemical mechanical polisher (CMP) technology for the generation of 300mm/0.18 to 0.13{mu}m semiconductor devices. Ebara has developed a CMP system for 300mm devices for I300I and Selete (semiconductor high-technologies). The polishing process conditions are set for the time being based on those for the 200mm devices, and the driver and machine structures are set at 2.25 times larger than those for the 200mm devices. Its space requirement is compacter at 1.3 times increase. The company has adopted a concept of `dry-in and dry-out,` which is not common for a CMP. This needs integration of the washer with the polisher, and aerodynamic designs for dust-free conditions. These are already developed for the 200mm devices, and applicable to the 300mm devices without causing any problem. The special chamber for the conventional CMP can be dispensed with, reducing cost. Expendables, such as slurry pad, are being developed to double their service lives and halve their consumption. 8 figs.

  20. Mechanical performance of styrene-butadiene-rubber filled with carbon nanoparticles prepared by mechanical mixing

    Energy Technology Data Exchange (ETDEWEB)

    Saatchi, M.M. [Department of Chemical and Petroleum Engineering, Sharif University of Technology, P.O. Box 11155-9465, Tehran (Iran, Islamic Republic of); Shojaei, A., E-mail: akbar.shojaei@sharif.edu [Department of Chemical and Petroleum Engineering, Sharif University of Technology, P.O. Box 11155-9465, Tehran (Iran, Islamic Republic of)

    2011-09-15

    Highlights: {yields} We compare influence of carbon blacks and carbon nanotube on properties of SBR. {yields} We model mechanical behavior of SBR nanocomposites by the micromechanical model. {yields} Mechanical properties of carbon black/SBR is greatly dominated by bound rubber. {yields} Mechanical properties of SBR/nanotube is governed by big aspect ratio of nanotube. - Abstract: Reinforcement of styrene-butadiene-rubber (SBR) was investigated using two different carbon blacks (CBs) with similar particle sizes, including highly structured CB and conventional CB, as well as multi-walled carbon nanotube (MWCNT) prepared by mechanical mixing. The attempts were made to examine reinforcing mechanism of these two different classes of carbon nanoparticles. Scanning electron microscopy and electrical conductivity measurement were used to investigate morphology. Tensile, cyclic tensile and stress relaxation analyses were performed. A modified Halpin-Tsai model based on the concept of an equivalent composite particle, consisting of rubber bound, occluded rubber and nanoparticle, was proposed. It was found that properties of CB filled SBR are significantly dominated by rubber shell and occluded rubber in which molecular mobility is strictly restricted. At low strains, these rubber constituents can contribute in hydrodynamic effects, leading to higher elastic modulus. However, at higher strains, they contribute in stress hardening resulting in higher elongation at break and higher tensile strength. These elastomeric regions can also influence stress relaxation behaviors of CB filled rubber. For SBR/MWCNT, the extremely great inherent mechanical properties of nanotube along with its big aspect ratio were postulated to be responsible for the reinforcement while their interfacial interaction was not so efficient.

  1. Functional Median Polish

    KAUST Repository

    Sun, Ying

    2012-08-03

    This article proposes functional median polish, an extension of univariate median polish, for one-way and two-way functional analysis of variance (ANOVA). The functional median polish estimates the functional grand effect and functional main factor effects based on functional medians in an additive functional ANOVA model assuming no interaction among factors. A functional rank test is used to assess whether the functional main factor effects are significant. The robustness of the functional median polish is demonstrated by comparing its performance with the traditional functional ANOVA fitted by means under different outlier models in simulation studies. The functional median polish is illustrated on various applications in climate science, including one-way and two-way ANOVA when functional data are either curves or images. Specifically, Canadian temperature data, U. S. precipitation observations and outputs of global and regional climate models are considered, which can facilitate the research on the close link between local climate and the occurrence or severity of some diseases and other threats to human health. © 2012 International Biometric Society.

  2. Fabrication and Characterization of FeNiCr Matrix-TiC Composite for Polishing CVD Diamond Film

    Institute of Scientific and Technical Information of China (English)

    Zhuji Jin; Zewei Yuan; Renke Kang; Boxian Dong

    2009-01-01

    Dynamic friction polishing (DFP) is one of the most promising methods appropriate for polishing CVD diamond film with high efficiency and low cost.By this method CVD diamond film is polished through being simply pressed against a metal disc rotating at a high speed utilizing the thermochemical reaction occurring as a result of dynamic friction between them in the atmosphere.However, the relatively soft materials such as stainless steel, cast iron and nickel alloy widely used for polishing CVD diamond film are easy to wear and adhere to diamond film surface, which may further lead to low efficiency and poor polishing quality.In this paper, FeNiCr matrix-TiC composite used as grinding wheel for polishing CVD diamond film was obtained by combination of mechanical alloying (MA) and spark plasma sintering (SPS).The process of ball milling,composition, density, hardness, high-temperature oxidation resistance and wear resistance of the sintered piece were analyzed.The results show that TiC was introduced in MA-SPS process and had good combination with FeNiCr matrix and even distribution in the matrix.The density of composite can be improved by mechanical alloying.The FeNiCr matrix-TiC composite obtained at 1273 K was found to be superior to at 1173 K sintering in hardness, high-temperature oxidation resistance and wearability.These properties are more favorable than SUS304 for the preparation of high-performance grinding wheel for polishing CVD diamond film.

  3. Oculomotor preparation as a rehearsal mechanism in spatial working memory.

    Science.gov (United States)

    Pearson, David G; Ball, Keira; Smith, Daniel T

    2014-09-01

    There is little consensus regarding the specific processes responsible for encoding, maintenance, and retrieval of information in visuo-spatial working memory (VSWM). One influential theory is that VSWM may involve activation of the eye-movement (oculomotor) system. In this study we experimentally prevented healthy participants from planning or executing saccadic eye-movements during the encoding, maintenance, and retrieval stages of visual and spatial working memory tasks. Participants experienced a significant reduction in spatial memory span only when oculomotor preparation was prevented during encoding or maintenance. In contrast there was no reduction when oculomotor preparation was prevented only during retrieval. These results show that (a) involvement of the oculomotor system is necessary for optimal maintenance of directly-indicated locations in spatial working memory and (b) oculomotor preparation is not necessary during retrieval from spatial working memory. We propose that this study is the first to unambiguously demonstrate that the oculomotor system contributes to the maintenance of spatial locations in working memory independently from the involvement of covert attention. Copyright © 2014 The Authors. Published by Elsevier B.V. All rights reserved.

  4. Preparation and mechanical property of polymer-based biomaterials

    International Nuclear Information System (INIS)

    Zhang, P; Chen, G; Zheng, X F

    2010-01-01

    The porous polymer-based biomaterial has been synthesized from PLGA, dioxane and tricalcium phosphate (TCP) by low-temperature deposition process. The deformation behaviours and fracture mechanism of polymer-based biomaterials were investigated using the compression test and the finite element (FE) simulation. The results show that the stress-strain curve of compression process includes linear elastic stage I, platform stage II and densification stage III, and the fracture mechanism can be considered as brittle fracture.

  5. Buffered Electrochemical Polishing of Niobium

    Energy Technology Data Exchange (ETDEWEB)

    Ciovati, Gianluigi [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States); Tian, Hui [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States); College of William and Mary, Williamsburg, VA (United States); Corcoran, Sean [Virginia Polytechnic Inst. and State Univ. (Virginia Tech), Blacksburg, VA (United States)

    2011-03-01

    The standard preparation of superconducting radio-frequency (SRF) cavities made of pure niobium include the removal of a 'damaged' surface layer, by buffered chemical polishing (BCP) or electropolishing (EP), after the cavities are formed. The performance of the cavities is characterized by a sharp degradation of the quality factor when the surface magnetic field exceeds about 90 mT, a phenomenon referred to as 'Q-drop.' In cavities made of polycrystalline fine grain (ASTM 5) niobium, the Q-drop can be significantly reduced by a low-temperature (? 120 °C) 'in-situ' baking of the cavity if the chemical treatment was EP rather than BCP. As part of the effort to understand this phenomenon, we investigated the effect of introducing a polarization potential during buffered chemical polishing, creating a process which is between the standard BCP and EP. While preliminary results on the application of this process to Nb cavities have been previously reported, in this contribution we focus on the characterization of this novel electrochemical process by measuring polarization curves, etching rates, surface finish, electrochemical impedance and the effects of temperature and electrolyte composition. In particular, it is shown that the anodic potential of Nb during BCP reduces the etching rate and improves the surface finish.

  6. Mechanical bowel preparation and oral antibiotic prophylaxis in colorectal surgery: Analysis of evidence and narrative review.

    Science.gov (United States)

    Badia, Josep M; Arroyo-García, Nares

    2018-05-14

    The role of oral antibiotic prophylaxis and mechanical bowel preparation in colorectal surgery remains controversial. The lack of efficacy of mechanical preparation to improve infection rates, its adverse effects, and multimodal rehabilitation programs have led to a decline in its use. This review aims to evaluate current evidence on antegrade colonic cleansing combined with oral antibiotics for the prevention of surgical site infections. In experimental studies, oral antibiotics decrease the bacterial inoculum, both in the bowel lumen and surgical field. Clinical studies have shown a reduction in infection rates when oral antibiotic prophylaxis is combined with mechanical preparation. Oral antibiotics alone seem to be effective in reducing infection in observational studies, but their effect is inferior to the combined preparation. In conclusion, the combination of oral antibiotics and mechanical preparation should be considered the gold standard for the prophylaxis of postoperative infections in colorectal surgery. Copyright © 2018 AEC. Publicado por Elsevier España, S.L.U. All rights reserved.

  7. Polish Higher Education: Intersectoral Distinctiveness

    Science.gov (United States)

    Musial, Joanna

    2014-01-01

    This study analyzes degrees of differences between the private and public sectors of Polish higher education. It finds them to be strong: Polish private institutions function very differently from Polish public institutions and these differences correspond with those found in the literature on higher education elsewhere in the world. Polish…

  8. Reduction mechanism of Ni2+ into Ni nanoparticles prepared from ...

    Indian Academy of Sciences (India)

    journal of. March 2009 physics pp. 577–586. Reduction mechanism of Ni2+ into Ni ..... and at high field, no domain wall is available and hence, the system becomes a .... [23] J Ding, T Tsuzuki, P G McCormick and R Street, J. Phys. D: Appl.

  9. Hydroxyapatite nanocrystals: simple preparation, characterization and formation mechanism.

    Science.gov (United States)

    Mohandes, Fatemeh; Salavati-Niasari, Masoud; Fathi, Mohammadhossein; Fereshteh, Zeinab

    2014-12-01

    Crystalline hydroxyapatite (HAP) nanoparticles and nanorods have been successfully synthesized via a simple precipitation method. To control the shape and particle size of HAP nanocrystals, coordination ligands derived from 2-hydroxy-1-naphthaldehyde were first prepared, characterized by Fourier transform infrared (FT-IR) and proton nuclear magnetic resonance ((1)H-NMR) spectroscopies, and finally applied in the synthesis process of HAP. On the other hand, the HAP nanocrystals were also characterized by several techniques including powder X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM). According to the FE-SEM and TEM micrographs, it was found that the morphology and crystallinity of the HAP powders depended on the coordination mode of the ligands. Copyright © 2014 Elsevier B.V. All rights reserved.

  10. Montmorillonite polyaniline nanocomposites: Preparation, characterization and investigation of mechanical properties

    International Nuclear Information System (INIS)

    Soundararajah, Q.Y.; Karunaratne, B.S.B.; Rajapakse, R.M.G.

    2009-01-01

    The interest in clay polymer nanocomposites (CPN) materials, initially developed by researchers at Toyota, has grown dramatically over the last decade. They have attracted great interest, both in industry and in academia, because they often exhibit remarkable improvement in materials' properties when compared with virgin polymer or conventional micro- and macro-composites. These improvements can include high moduli, increased strength and heat resistance, decreased gas permeability and flammability, optical transparency and increased biodegradability of biodegradable polymers. Such enhancement in the properties of nanocomposites occurs mostly due to their unique phase morphology and improved interfacial properties. Because of these enhanced properties they find applications in the fields of electronics, automobile industry, packaging, and construction. This study aims at investigating the mechanical property enhancement of polyaniline (PANI) intercalated with montmorillonite (MMT) clay. The MMT-PANI nanocomposites displayed improved mechanical properties compared to the neat polymer or clay. The enhancement was achieved at low clay content probably due to its exfoliated structure. The increased interfacial areas and improved bond characteristics may attribute to the mechanical property enhancement

  11. Transformation mechanism of nutrient elements in the process of biochar preparation for returning biochar to soil

    Institute of Scientific and Technical Information of China (English)

    Shuangshuang Tian; Zhongxin Tan; Alfreda Kasiulienė; Ping Ai

    2017-01-01

    Returning biochar to soil is a heavily researched topic because biochar functions well for soil improvement. There is a significant loss of nutrients, which occurs during biochar preparation before biochar is returned to soil, thereby seriously undermining biochar's efficacy. Therefore, the transformation mechanisms of biochar pH, mass, nutrients and metals during pyrolysis under different atmospheres and temperatures were studied such that the best method for biochar preparation could be developed. Several conclusions can be reached: (1) a CO2 atmosphere is better than a N2 atmosphere for biochar preparation, although preparation in a CO2 atmosphere is not a common practice for biochar producers; (2) 350 ℃ is the best temperature for biochar preparation because the amount of nutrient loss is notably low based on the premise of straw transferred into biochar; and (3) transforming mechanisms of pH, N, P and K are also involved in the biochar preparation process.

  12. Sexual activity of Polish adults

    Directory of Open Access Journals (Sweden)

    Beata Pastwa-Wojciechowska

    2014-03-01

    Full Text Available Aim. The purpose of this research was to explore the subject of sexual activity in the Polish population, with special focus on age and gender differences, and sexual infidelity. Sexual activity is one of the basic factors in initiating and maintaining relationships. On the one hand, sexual activity enables us to meet natural needs and maintain an intimate relationship with another human being; on the other, it may allow us to overcome loneliness and social isolation by providing the opportunity to express feelings of closeness and unity. Material and method. The research was conducted on a representative group of 3,200 Poles aged between 15–49, with the support of a well-known Polish research company – TNS OBOP. Face-to-face and Pencil and Paper (PAPI interviews were carried out. Results. The results focus on two main issues: the age and motives of sexual initiation among teenagers (with a significant percentage starting their sexual activity at the age of 15, and the quality of the sexual lives of adults (average number of sexual partners, sexual infidelity and sexual satisfaction. Conclusion. There is dependence between the type of relationship and the performance or non-performance of sexual activity, as well as the quality of the relationship. Among both adolescents and adults, remaining in a stable relationship (partnership or marriage promotes loyalty. The performance of sexual goals turns out to be an important mechanism regulating the interpersonal aspects of a relationship, influencing their perception and evaluation.

  13. Colon and rectal surgery for cancer without mechanical bowel preparation: one-center randomized prospective trial.

    Science.gov (United States)

    Scabini, Stefano; Rimini, Edoardo; Romairone, Emanuele; Scordamaglia, Renato; Damiani, Giampiero; Pertile, Davide; Ferrando, Valter

    2010-04-30

    Mechanical bowel preparation is routinely done before colon and rectal surgery, aimed at reducing the risk of postoperative infectious complications. The aim of the study was to assess whether elective colon and rectal surgery can be safely performed without preoperative mechanical bowel preparation. Patients undergoing elective colon and rectal resections with primary anastomosis were prospectively randomized into two groups. Group A had mechanical bowel preparation with polyethylene glycol before surgery, and group B had their surgery without preoperative mechanical bowel preparation. Patients were followed up for 30 days for wound, anastomotic, and intra-abdominal infectious complications. Two hundred forty four patients were included in the study, 120 in group A and 124 in group B. Demographic characteristics, type of surgical procedure and type of anastomosis did not significantly differ between the two groups. There was no difference in the rate of surgical infectious complications between the two groups but the overall infectious complications rate was 20.0% in group A and 11.3% in group B (p .05). Wound infection (p = 0.18), anastomotic leak (p = 0.52), and intra-abdominal abscess (p = 0.36) occurred in 9.2%, 5.8%, and 5.0% versus 4.8%, 4.0%, and 2.4%, respectively. No mechanical bowel preparation seems to be safe also in rectal surgery. These results suggest that elective colon and rectal surgery may be safely performed without mechanical preparation.

  14. Polish Semantic Parser

    Directory of Open Access Journals (Sweden)

    Agnieszka Grudzinska

    2000-01-01

    Full Text Available Amount of information transferred by computers grows very rapidly thus outgrowing the average man's capability of reception. It implies computer programs increase in the demand for which would be able to perform an introductory classitication or even selection of information directed to a particular receiver. Due to the complexity of the problem, we restricted it to understanding short newspaper notes. Among many conceptions formulated so far, the conceptual dependency worked out by Roger Schank has been chosen. It is a formal language of description of the semantics of pronouncement integrated with a text understanding algorithm. Substantial part of each text transformation system is a semantic parser of the Polish language. It is a module, which as the first and the only one has an access to the text in the Polish language. lt plays the role of an element, which finds relations between words of the Polish language and the formal registration. It translates sentences written in the language used by people into the language theory. The presented structure of knowledge units and the shape of understanding process algorithms are universal by virtue of the theory. On the other hand the defined knowledge units and the rules used in the algorithms ure only examples because they are constructed in order to understand short newspaper notes.

  15. The influence of polishing techniques on pre-polymerized CAD\\CAM acrylic resin denture bases.

    Science.gov (United States)

    Alammari, Manal Rahma

    2017-10-01

    Lately, computer-aided design and computer-aided manufacturing (CAD/CAM) has broadly been successfully employed in dentistry. The CAD/CAM systems have recently become commercially available for fabrication of complete dentures, and are considered as an alternative technique to conventionally processed acrylic resin bases. However, they have not yet been fully investigated. The purpose of this study was to inspect the effects of mechanical polishing and chemical polishing on the surface roughness (Ra) and contact angle (wettability) of heat-cured, auto-cured and CAD/CAM denture base acrylic resins. This study was conducted at the Advanced Dental Research Laboratory Center of King Abdulaziz University from March to June 2017. Three denture base materials were selected: heat cure poly-methylmethacrylate resin, thermoplastic (polyamide resin) and (CAD\\CAM) denture base resin. Sixty specimens were prepared and divided into three groups, twenty in each. Each group was divided according to the polishing techniques into (Mech P) and (Chem P), ten specimens in each; surface roughness and wettability were investigated. Data were analyzed by SPSS version 22, using one-way ANOVA and Pearson coefficient. One-way analysis of variance (ANOVA) and post hoc tests were used for comparing the surface roughness values between three groups which revealed a statistical significant difference between them (p 1 CAD\\CAM denture base material (group III) showed the least mean values (1.08±0.23, 1.39±0.31, Mech P and Chem P respectively). CAD/CAM showed the least contact angle in both polishing methods, which were statistically significant at 5% level (p=0.034 and pCAD\\CAM denture base resin with superior smooth surface compared to chemical polishing. Mechanical polishing is considered the best effective polishing technique. CAD/CAM denture base material should be considered as the material of choice for complete denture construction in the near future, especially for older dental

  16. Preparation and Mechanical Properties of Pressed Straw Concrete Brick

    Science.gov (United States)

    Sumarni, S.; Wijanarko, W.

    2018-03-01

    Rice straws have been widely used as wall filler material in China, Australia, and United States, by spinning them into hays with an approximate dimension of 40 cm of height, 40cm of thickness and 60 cm of width, using a machine. Then, the hays are placed into a wall frame until they fill it completely. After that, the wall frame is covered with wire mesh and plastered. In this research, rice straws are to be used as concrete brick fillers, by pressing the straws into hays and then putting them into the concrete brick mold along with mortar. The objective of this research is to investigate the mechanical properties of concrete brick, namely: compressive strength, specific gravity, and water absorption power. This research used experimental research method. It was conducted by using concrete bricks which had 400 cm of width, 200 cm of height, and 100 cm of thickness, made from rice straws, cement, sand, and water as the test sample. The straws were each made different by their volume. The mortars used in this research were made from cement, sand, and water, with the ratio of 1:7:0.5. The concrete bricks were made by pressing straws mixed with glue into hays, and then cut by determined variations of volume. The variations of hays volume were 0 m3, 0.000625 m3, 0.00075 m3, 0.000875 m3, 0.00125 m3, 0.0015 m3, 0.00175 m3, 0.001875 m3, 0.00225 m3, and 0.002625 m3. There were 3 samples for each volumes of hays. The result shows that the straw concrete bricks reached the maximum compressive strength of 1.92 MPa, specific gravity of 1,702 kg/m3, and water absorption level of 3.9 %. Based on the provided measurements of products in the Standar Nasional Indonesia (Indonesian product standardization), the concrete bricks produced attained the prescribed standard quality.

  17. Combination oral and mechanical bowel preparations decreases complications in both right and left colectomy.

    Science.gov (United States)

    Midura, Emily F; Jung, Andrew D; Hanseman, Dennis J; Dhar, Vikrom; Shah, Shimul A; Rafferty, Janice F; Davis, Bradley R; Paquette, Ian M

    2018-03-01

    Before elective colectomy, many advocate mechanical bowel preparation with oral antibiotics, whereas enhanced recovery pathways avoid mechanical bowel preparations. The optimal preparation for right versus left colectomy is also unclear. We sought to determine which strategy for bowel preparation decreases surgical site infection (SSI) and anastomotic leak (AL). Elective colectomies from the National Surgical Quality Improvement Program colectomy database (2012-2015) were divided by (1) type of bowel preparation: no preparation (NP), mechanical preparation (MP), oral antibiotics (PO), or mechanical and oral antibiotics (PO/MP); and (2) type of colonic resection: right, left, or segmental colectomy. Univariate and multivariate analyses identified predictors of SSI and AL, and their risk-adjusted incidence was determined by logistic regression. When analyzed as the odds ratio compared with NP, the PO and PO/MP groups were associated with a decrease in SSI (PO = 0.70 [0.55-0.88] and PO/MP = 0.47 [0.42-0.53]; P < .01). Use of PO/MP was associated with a decrease in SSI across all types of resections (right colectomy = 0.40 [0.33-0.50], left colectomy = 0.57 [0.47-0.68], and segmental colectomy = 0.43 (0.34-0.54); P < .01). Similarly, use of PO/MP was associated with a decrease in AL in left colectomy = 0.50 ([0.37-0.69]; P < .01) and segmental colectomy = 0.53 ([0.36-0.80]; P < .01). Mechanical bowel preparation with oral antibiotics is the preferred preoperative preparation strategy in elective colectomy because of decreased incidence of SSI and AL. Copyright © 2017 Elsevier Inc. All rights reserved.

  18. Factors influencing the surface quality of polished tool steels

    International Nuclear Information System (INIS)

    Rebeggiani, S; Rosén, B-G

    2014-01-01

    Today’s demands on surface quality of moulds for injection moulding of plastic components involve no/low defect contents and roughness levels in the nm-range for high gloss applications. Material properties as well as operating conditions influence the mould finish, and thus the final surface of moulded products. This paper focuses on how particle content and different polishing strategies influence final surface qualities of moulds. Visual estimations of polished tool steel samples were combined with non-contact 3D-surface texture analysis in order to correlate traditional assessments to more quantitative methods, and to be able to analyse the surfaces at nanometre-level. It was found that steels with a lower proportion of particles, like carbides and oxides, gave rise to smoother polished surfaces. In a comparative study of polishers from different polishing shops, it was found that while different surface preparation strategies can lead to similar final roughness, similar preparation techniques can produce high-quality surfaces from different steel grades. However, the non-contact 3D-surface texture analysis showed that not all smooth polished surfaces have desirable functional topographies for injection moulding of glossy plastic components. (paper)

  19. Reel-to-reel substrate tape polishing system

    Energy Technology Data Exchange (ETDEWEB)

    Selvamanickam, Venkat; Gardner, Michael T.; Judd, Raymond D.; Weloth, Martin; Qiao, Yunfei

    2005-06-21

    Disclosed is a reel-to-reel single-pass mechanical polishing system (100) suitable for polishing long lengths of metal substrate tape (124) used in the manufacture of high-temperature superconductor (HTS) coated tape, including multiple instantiations of a polishing station (114) in combination with a subsequent rinsing station (116) arranged along the axis of the metal substrate tape (124) that is translating between a payout spool (110a) and a take-up spool (110b). The metal substrate tape obtains a surface smoothness that is suitable for the subsequent deposition of a buffer layer.

  20. EFFECTS OF POLISHING TIME AND THERMALCYCLINGON THE MICROLEAKAGE OF FOUR TOOTH –COLOURED DIRECT RESTORATIVE MATERIALS

    Directory of Open Access Journals (Sweden)

    V MORTAZAVI

    2002-09-01

    Full Text Available Introdaction. Microleakage has been recognized as a major clinical problem with direct filled dental restorations.The purpose of this study was to investigate and to compare the microleakage of four direct filled tooth-coloured materials, evaluation the effects of polishing time and thermocycling on the microleakage of these materials. Methods. Wedge-shaped class V cavities were prepared on buccal and lingual surfaces of 96 intact extracted human molar teeth. The teeth were randomly divided into three treatment groups and four subgroups. The cavities of each subgroup were filled using one of these materials: a conventional glass ionomer; a resin modified glass ionomer; a composite resin and a compomer. Polishing in the teeth of group 1 was done immediately after placement of restorations and in group 2 one week later. In group 3 delayed polishing and thermocycling (X100 was done. All of the teeth were stored in distilled water for one week and then stained with dye, sectioned, and scored for microleakage on occlusal and cervical edges. Results were statistically analyzed by Kruskal wallis and Mann whitney tests. Results. There was a statistically difference between the microleakage scores of four materials (P < 0.001. Immediately polished glass ionomer and compomer groups have significantly more microleakage than delayed polished groups (P < 0.001. Thermocycting could infulence the microleakage of composite on cervical edges (P < 0.05. Discussion. The precense of differences between the nature of materials and also the surface treatment such as primer or etchant application could influence the microleakage. The prescence of differences in reaction rate between the materials and the time that they reach to their adequate mechanical strength and adhesive bond strength lead to presence of differences between the effect of polishing time on the microleakage scores of materials.

  1. Mechanical and Tribological Characteristics of the AMC, Prepared by P/M Route along with Thermo-Mechanical Treatment

    Science.gov (United States)

    Mohapatra, Sambit Kumar; Maity, Kalipada; Bhuyan, Subrat Kumar; Prasad Satpathy, Mantra

    2018-03-01

    Thermo mechanical treatments have the ameliorated impacts on the mechanical and tribological properties of powder metallurgy components. In this investigation an aluminium matrix composite (AMC) {Al (92) + Mg (5) + Gr (1) + Ti (2)} has been prepared by following powder metallurgy technique, with double axial compaction and ulterior sintering. Secondary thermo-mechanical treatment i.e. hot extrusion through mathematical contoured cosine profiled die was considered. The die causes minimum velocity relative differences across the extrusion exit cross-section, which provides smooth material flow. Comparative result analysis for the mechanical and tribological characteristics of the specimen before and after extrusion was concentrated. Extrusion engenders significant amount of improvements of the properties those are attributed to excellent bond strength and uniform density distribution due to high compressive stress. Oxidative and delaminated wear mechanisms were found predominating type. To furnish the suitable explanation scanning electron microscopies have been performed for the wear surfaces.

  2. Polish Americans. Second, Revised Edition.

    Science.gov (United States)

    Lopata, Helen Znaniecka

    This book examines Polonia, the Polish ethnic community in America created by three giant waves of immigration between 1880 and 1990. The complicated history of this ethnic group is reflected in the lives of increasing numbers of Polish Americans, including recent immigrants brought by political and economic changes, as they achieve middle class…

  3. Preparation and mechanical properties of photo-crosslinked poly(trimethylene carbonate) and nano-hydroxyapatite composites

    NARCIS (Netherlands)

    Geven, Mike Alexander; Barbieri, D.; Yuan, Huipin; de Bruijn, Joost Dick; Grijpma, Dirk W.

    2015-01-01

    Composite materials of photo-crosslinked poly(trimethylene carbonate) and nanoscale hydroxyapatite were prepared and their mechanical characteristics for application as orbital floor implants were assessed. The composites were prepared by solvent casting poly(trimethylene carbonate) macromers with

  4. Low temperature preparation of α-tricalcium phosphate and its mechanical properties

    Directory of Open Access Journals (Sweden)

    Song Wang

    2017-06-01

    Full Text Available In this work, α-tricalcium phosphate (α-TCP was successfully prepared by the thermal transformation of amorphous calcium phosphate (ACP precursor. β-cyclodextrin (β-CD was used for preparation of ACP precursor and played an important role in designing its special structure. The phase composition and microstructures of the obtained α-TCP at different annealing temperature were analysed by X-ray diffraction and scanning electron microscope, and confirmed that α-TCP can be prepared at 650°C for 3 h using ACP as precursor, which is much lower than the phase transition temperature of α-TCP. Mechanical properties were tested 24 h after mixing the obtained α-TCP with 30 wt.% of deionised water. The compressive strength and the flexural strength were 26.4MPa and 12.0MPa, respectively. The flexural strength was higher than that of α-TCP prepared by other methods.

  5. Preparation, heat treatment, and mechanical properties of the uranium-5 weight percent chromium eutectic alloy

    International Nuclear Information System (INIS)

    Townsend, A.B.

    1980-10-01

    The eutectic alloy of uranium-5 wt % chromium (U-5Cr) was prepared from high-purity materials and cast into 1-in.-thick ingots. This material was given several simple heat treatments, the mechanical properties of these heat-treated samples were determined; and the microstructure was examined. Some data on the melting point and transformation temperatures were obtained

  6. Research on high-efficiency polishing technology of photomask substrate

    Science.gov (United States)

    Zhao, Shijie; Xie, Ruiqing; Zhou, Lian; Liao, Defeng; Chen, Xianhua; Wang, Jian

    2018-03-01

    A method of photomask substrate fabrication is demonstrated ,that the surface figure and roughness of fused silica will converge to target precision rapidly with the full aperture polishing. Surface figure of optical flats in full aperture polishing processes is primarily dependent on the surface profile of polishing pad, therefor, a improved function of polishing mechanism was put forward based on two axis lapping machine and technology experience, and the pad testing based on displacement sensor and the active conditioning method of the pad is applied in this research. Moreover , the clamping deformation of the thin glass is solved by the new pitch dispensing method. The experimental results show that the surface figure of the 152mm×152mm×6.35mm optical glass is 0.25λ(λ=633nm) and the roughness is 0.32nm ,which has meet the requirements of mask substrate for 90 45nm nodes.

  7. Chemical polishing of epitoxial silicon wafer

    International Nuclear Information System (INIS)

    Osada, Shohei

    1978-01-01

    SSD telescopes are used for the determination of the kind and energy of charged particles produced by nuclear reactions, and are the equipments combining ΔE counters and E counters. The ΔE counter is a thin SSD which is required to be thin and homogeneous enough to get the high resolution of measurement. The SSDs for ΔE counters have so far been obtained by polishing silicon plates mechanically and chemically or by applying electrolytic polishing method on epitaxial silicon wafers, but it was very hard to obtain them. The creative etching equipment and technique developed this time make it possible to obtain thin SSDs for ΔE counters. The outline of the etching equipment and its technique are described in the report. The etching technique applied for the silicon films for ΔE counters with thickness of about 10 μm was able to be experimentally established in this study. (Kobatake, H.)

  8. Damage-free polishing of monocrystalline silicon wafers without chemical additives

    International Nuclear Information System (INIS)

    Biddut, A.Q.; Zhang, L.C.; Ali, Y.M.; Liu, Z.

    2008-01-01

    This investigation explores the possibility and identifies the mechanism of damage-free polishing of monocrystalline silicon without chemical additives. Using high resolution electron microscopy and contact mechanics, the study concludes that a damage-free polishing process without chemicals is feasible. All forms of damages, such as amorphous Si, dislocations and plane shifting, can be eliminated by avoiding the initiation of the β-tin phase of silicon during polishing. When using 50 nm abrasives, the nominal pressure to achieve damage-free polishing is 20 kPa

  9. Microstructures and formation mechanism of W–Cu composite coatings on copper substrate prepared by mechanical alloying method

    International Nuclear Information System (INIS)

    Meng, Yunfei; Shen, Yifu; Chen, Cheng; Li, Yongcan; Feng, Xiaomei

    2013-01-01

    In the present work, high-energy mechanical alloying (MA) method was applied to prepare tungsten–copper composite coatings on pure copper surface using a planetary ball mill. During mechanical alloying process, grains on the surface layer of substrate were refined and the substrate surface was activated as a result of repeated collisions by a large number of flying balls along with powder particles. The repeated ball-to-substrate collisions resulted in the deposition of coatings. The microstructures and elemental and phase composition of mechanically alloyed coatings at different milling durations during mechanical alloying process were studied using scanning electron microscopy (SEM), X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDS). Microhardness tests were carried out to examine the mechanical properties of the coatings. The results showed that the coatings and the substrates were well bonded, and with the increase of the milling duration, multi-layered coatings with different structures were generated and the coatings became denser. The microhardness tests showed that the maximum microhardness of the coatings reached HV 0.1 228, showing a threefold improvement upon the substrate. And the cross-sectional microhardness values of the processed sample changed gradually, which gave a proof for the cushioning and sustaining functions of the multi-layered coatings. A reasonable formation mechanism of coatings on bulk materials with metallic immiscible system by mechanical alloying method was presented.

  10. Polishing large NaCl windows on a continuous polisher

    International Nuclear Information System (INIS)

    Williamson, R.

    1979-01-01

    The Helios and Antares CO 2 fusion laser systems incorporate numerous large sodium chloride windows. These must be refinished periodically, making necessary a consistent and predictable polishing capability. A continuous polisher (or annular lap) which might at Kirtland's Developmental Optical Facility. Large NaCl windows had not been polished on this type of machine. The machine has proven itself capable of producing lambda/16 figures at 633 nm (HeNe) with extremely smooth surfaces on glass. Since then, we have been working exclusively on NaCl optics. Due to different polishing parameters between NaCl and glass, and the slight solubility of the pitch in the slurry, this phase presents new problems. The work on glass will be reviewed. Results on NaCl to date will be reported. The potential of this type of machine relative to prisms, thin and irregularly shaped optics will be discussed

  11. Preparation of sago starch-based biocomposite reinforced microfibrillated cellulose of bamboo assisted by mechanical treatment

    Science.gov (United States)

    Silviana, S.; Hadiyanto, H.

    2017-06-01

    The utilization of green composites by using natural fibres is developed due to their availability, ecological benefits, and good properties in mechanical and thermal. One of the potential sources is bamboo that has relative high cellulose content. This paper was focused on the preparation of sago starch-based reinforced microfribrillated cellulose of bamboo that was assisted by mechanical treatment. Microfibrillated cellulose of bamboo was prepared by isolation of cellulose with chemical treatment. Preparation of bamboo microfibrillated cellulose was conducted by homogenizers for dispersing bamboo cellulose, i.e. high pressure homogenizer and ultrasonic homogenizer. Experiments were elaborated on several variables such as the concentration of bamboo microfibrillated cellulose dispersed in water (1-3 %w) and the volume of microfibrillated cellulose (37.5-75%v). Four %w of sago starch solution was mixed with bamboo microfibrillated cellulose and glycerol with plasticizer and citric acid as cross linker. This paper provided the analysis of tensile strength as well as SEM for mechanical and morphology properties of the biocomposite. The results showed that the preparation of sago starch-based biocomposite reinforced bamboo microfibrillated cellulose by using ultrasonic homogenizer yielded the highest tensile strength and well dispersed in the biocomposite.

  12. TiTaCN-Co cermets prepared by mechanochemical technique: microstructure and mechanical properties

    OpenAIRE

    Fides, Martin; Hvizdoš, P.; Balko, Ján; Chicardi, E.; Gotor, F.J.

    2016-01-01

    Microstructure and mechanical characterization of (Ti,Ta)(C,N)-Co based solid solution cermets prepared by two mechanochemical synthesis processes (one- and two-step milling) and a pressureless sintering in protective helium atmosphere. Materials with composition of TixTa1- xC0.5N0.5-20%Co with two different Ti/Ta ratios (x = 0.9 and x = 0.95) were developed to prepare four groups of experimental materials. Microstructures were observed using confocal microscopy and grain size was ev...

  13. Mechanical behavior of mullite green disks prepared by thermal consolidation with different starches

    International Nuclear Information System (INIS)

    Talou, M.H.; Tomba Martinez, A.G.; Camerucci, M.A.

    2011-01-01

    Mechanical behavior of porous green disks obtained by thermal consolidation of mullite suspensions with cassava and potato starches was studied by diametral compression testing. Disks (thickness/diameter ≤ 0.25) were prepared by thermal treatment (70-80 °C, 2h) of mullite (75 vol%)/starch (25 vol%) of suspensions (40 vol%) pre-gelled at 55-60 °C, and dried (40 °C, 24 h). Samples were characterized by porosity measurements (50-55%) and microstructural analysis (SEM). Several mechanical parameters were determined: mechanical strength, Young's modulus, strain to fracture and yield stress. Typical crack patterns were analyzed and the fractographic analysis was performed by SEM. Mechanical results were related to the developed microstructures, the behavior of the starches in aqueous suspension, and the properties of the formed gels. For comparative purposes, mullite green disks obtained by burning out the starch (650 °C, 2h) were also mechanically evaluated. (author)

  14. Nanocrystalline-grained tungsten prepared by surface mechanical attrition treatment: Microstructure and mechanical properties

    International Nuclear Information System (INIS)

    Guo, Hong-Yan; Xia, Min; Wu, Zheng-Tao; Chan, Lap-Chung; Dai, Yong; Wang, Kun; Yan, Qing-Zhi; He, Man-Chao; Ge, Chang-Chun; Lu, Jian

    2016-01-01

    A nanostructured surface layer was fabricated on commercial pure tungsten using the method of surface mechanical attrition treatment (SMAT). The microstructure evolution of the surface layer was characterized by using scanning electron microscopy (SEM) and transmission electron microscopy (TEM) and its formation mechanism was discussed as well. Both refinement and elongation of the brittle W grains were confirmed. The elongated SMATed W was heavily strained, the maximum value of the strain at the grain boundaries reaches as high as 3–5%. Dislocation density in the SMATed W nanograins was found to be 5 × 10 12  cm −2 . The formation of the nanograins in the top surface layer of the W was ascribed to the extremely high strain and strain rate, as well as the multidirectional repetitive loading. Bending strength of commercial W could be improved from 825 MPa to 1850 MPa by SMAT process. Microhardness results indicated the strain range in SMATed W can reach up to 220 μm beneath the top surface. The notched Charpy testing results demonstrated that SMATed W possess higher ductility than that of commercial W. The top surface of the W plates with and without SMATe processing possesses residual compressive stress of about −881 MPa and −234 MPa in y direction, and −872 MPa and −879 MPa in x direction respectively. The improvement of toughness (DBTT shift) of SMATed W may be the synergistic effect of residual compressive stress, dislocation density improvement and microstructure refinement induced by SMAT processing. SMAT processing could be a complementary method to further decrease the DBTT value of tungsten based materials.

  15. Nanocrystalline-grained tungsten prepared by surface mechanical attrition treatment: Microstructure and mechanical properties

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Hong-Yan [State Key Laboratory for GeoMechanics and Deep Underground Engineering, China University of Mining and Technology, Beijing 100083 (China); Institute of Nuclear Materials, University of Science & Technology Beijing, Beijing 100083 (China); Department of Mechanical and Biomedical Engineering, City University of Hong Kong, Tae Chee Avenue Kowloon, Hong Kong 999077 (China); Xia, Min, E-mail: xmdsg@ustb.edu.cn [Institute of Nuclear Materials, University of Science & Technology Beijing, Beijing 100083 (China); Wu, Zheng-Tao [College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005 (China); Chan, Lap-Chung [Department of Mechanical and Biomedical Engineering, City University of Hong Kong, Tae Chee Avenue Kowloon, Hong Kong 999077 (China); Dai, Yong; Wang, Kun [Laboratory for Nuclear Materials, Paul Scherrer Institut, 5323 Villigen PSI (Switzerland); Yan, Qing-Zhi [Institute of Nuclear Materials, University of Science & Technology Beijing, Beijing 100083 (China); He, Man-Chao [State Key Laboratory for GeoMechanics and Deep Underground Engineering, China University of Mining and Technology, Beijing 100083 (China); Ge, Chang-Chun, E-mail: ccge@mater.ustb.edu.cn [Institute of Nuclear Materials, University of Science & Technology Beijing, Beijing 100083 (China); Lu, Jian, E-mail: jianlu@cityu.edu.hk [Department of Mechanical and Biomedical Engineering, City University of Hong Kong, Tae Chee Avenue Kowloon, Hong Kong 999077 (China)

    2016-11-15

    A nanostructured surface layer was fabricated on commercial pure tungsten using the method of surface mechanical attrition treatment (SMAT). The microstructure evolution of the surface layer was characterized by using scanning electron microscopy (SEM) and transmission electron microscopy (TEM) and its formation mechanism was discussed as well. Both refinement and elongation of the brittle W grains were confirmed. The elongated SMATed W was heavily strained, the maximum value of the strain at the grain boundaries reaches as high as 3–5%. Dislocation density in the SMATed W nanograins was found to be 5 × 10{sup 12} cm{sup −2}. The formation of the nanograins in the top surface layer of the W was ascribed to the extremely high strain and strain rate, as well as the multidirectional repetitive loading. Bending strength of commercial W could be improved from 825 MPa to 1850 MPa by SMAT process. Microhardness results indicated the strain range in SMATed W can reach up to 220 μm beneath the top surface. The notched Charpy testing results demonstrated that SMATed W possess higher ductility than that of commercial W. The top surface of the W plates with and without SMATe processing possesses residual compressive stress of about −881 MPa and −234 MPa in y direction, and −872 MPa and −879 MPa in x direction respectively. The improvement of toughness (DBTT shift) of SMATed W may be the synergistic effect of residual compressive stress, dislocation density improvement and microstructure refinement induced by SMAT processing. SMAT processing could be a complementary method to further decrease the DBTT value of tungsten based materials.

  16. Various bio-mechanical factors affecting heat generation during osteotomy preparation: A systematic review.

    Science.gov (United States)

    Chauhan, Chirag J; Shah, Darshana N; Sutaria, Foram B

    2018-01-01

    As implant site preparation and bone are critical precursors to primary healing, thermal and mechanical damage to the bone must be minimized during the preparation of the implant site. Moreover, excessively traumatic surgery can adversely affect the maturation of bone tissue at the bone/implant interface and consequently diminish the predictability of osseointegration. So, this study was carried out to evaluate the various biological and mechanical factors responsible for heat generation during osteotomy site preparation to reduce the same for successful osseointegration of dental implants. A broad search of the dental literature in PubMed added by manual search was performed for articles published between 1992 and December 2015. Various bio-mechanical factors related to dental implant osteotomy preparation such as dental implant drill designs/material/wear, drilling methods, type of irrigation, and bone quality were reviewed. Titles and abstracts were screened and articles which fulfilled the inclusion criteria were selected for a full-text reading. The initial database search yielded 123 titles, of which 59 titles were discarded after reading the titles and abstracts, 30 articles were again excluded based on inclusion and exclusion criteria, and finally 34 articles were selected for data extraction. Many biological and mechanical factors responsible for heat generation were found. Literatures of this review study have indicated that there are various bio-mechanical reasons, which affect the temperature rise during osteotomy and suggest that the amount of heat generation is a multifactorial in nature and it should be minimized for better primary healing of the implant site.

  17. Detection of paint polishing defects

    Science.gov (United States)

    Rebeggiani, S.; Wagner, M.; Mazal, J.; Rosén, B.-G.; Dahlén, M.

    2018-06-01

    Surface finish plays a major role on perceived product quality, and is the first thing a potential buyer sees. Today end-of-line repairs of the body of cars and trucks are inevitably to secure required surface quality. Defects that occur in the paint shop, like dust particles, are eliminated by manual sanding/polishing which lead to other types of defects when the last polishing step is not performed correctly or not fully completed. One of those defects is known as ‘polishing roses’ or holograms, which are incredibly hard to detect in artificial light but are clearly visible in sunlight. This paper will present the first tests with a measurement set-up newly developed to measure and analyse polishing roses. The results showed good correlations to human visual evaluations where repaired panels were estimated based on the defects’ intensity, severity and viewing angle.

  18. Tooth polishing: The current status

    Directory of Open Access Journals (Sweden)

    Madhuri Alankar Sawai

    2015-01-01

    Full Text Available Healthy teeth and gums make a person feel confident and fit. As people go about their daily routines and with different eating and drinking habits, the tooth enamel turns yellowish or gets stained. Polishing traditionally has been associated with the prophylaxis procedure in most dental practices, which patients know and expect. However, with overzealous use of polishing procedure, there is wearing of the superficial tooth structure. This would lead to more accumulation of local deposits. Also, it takes a long time for the formation of the fluoride-rich layer of the tooth again. Hence, now-a-days, polishing is not advised as a part of routine oral prophylaxis procedure but is done selectively based on the patients′ need. The article here, gives an insight on the different aspects of the polishing process along with the different methods and agents used for the same.

  19. Lysenko affair and Polish botany.

    Science.gov (United States)

    Köhler, Piotr

    2011-01-01

    This article describes the slight impact of Lysenkoism upon Polish botany. I begin with an account of the development of plant genetics in Poland, as well as the attitude of scientists and the Polish intelligentsia toward Marxist philosophy prior to the World War II. Next I provide a short history of the introduction and demise of Lysenkoism in Polish science, with a focus on events in botany, in context with key events in Polish science from 1939 to 1958. The article outlines the little effects of Lysenkoism upon botanists and their research, as well as how botanists for the most part rejected what was often termed the "new biology." My paper shows that though Lysenko's theories received political support, and were actively promoted by a small circle of scientists and Communist party activists, they were never accepted by most botanists. Once the political climate in Poland altered after the events of 1956, Lysenko's theories were immediately abandoned.

  20. Preparation of Baking-Free Brick from Manganese Residue and Its Mechanical Properties

    Directory of Open Access Journals (Sweden)

    Ping Wang

    2013-01-01

    Full Text Available The increasing amount of waste residue produced during the electrolytic preparation process of manganese has nowadays brought about serious environmental problems. The research on utilization of manganese slag has been a hot spot around the world. The utilization of manganese slag is not only environment friendly, but also economically feasible. In the current work, a summarization of the main methods to produced building materials from manganese slag materials was given. Baking-free brick, a promising building material, was produced from manganese slag with the addition of quicklime and cement. The physical properties, chemical composition, and mechanical performances of the obtained samples were measured by several analyses and characterization methods. Then the influence of adding materials and molding pressure during the preparation of baking-free brick samples on their compressive strength properties was researched. It is concluded that the baking-free brick prepared from manganese residue could have excellent compressive strength performance under certain formula.

  1. Sustained release of doxorubicin from zeolite-magnetite nanocomposites prepared by mechanical activation

    International Nuclear Information System (INIS)

    Arruebo, Manuel; Fernandez-Pacheco, Rodrigo; Irusta, Silvia; Arbiol, Jordi; Ibarra, M Ricardo; SantamarIa, Jesus

    2006-01-01

    Nanocomposites consisting of magnetite and FAU zeolite with a high surface area and adsorption capacity have been prepared by mechanical activation using high-energy milling at room temperature. FTIR results, as well as HRTEM, EFTEM, and XPS measurements, show that the resulting magnetic nanoparticles are covered by a thin aluminosilicate coating. A saturation magnetization as high as 16 emu g -1 and 94.2 Oe of coercivity were observed for the obtained composites. The main advantages of this synthesis procedure are (i) simplicity of the preparation procedure (ii) prevention of agglomeration of the magnetite nanoparticles to a large extent, and (iii) absence of free magnetite outside the zeolitic matrix. In addition, in vitro experiments revealed that the nanoparticles prepared were able to store and release substantial amounts of doxorubicin. In view of these advantages, these magnetic nanoparticles can be considered as potential candidates for drug-delivery applications

  2. Using quantum dots to tag subsurface damage in lapped and polished glass samples

    International Nuclear Information System (INIS)

    Williams, Wesley B.; Mullany, Brigid A.; Parker, Wesley C.; Moyer, Patrick J.; Randles, Mark H.

    2009-01-01

    Grinding, lapping, and polishing are finishing processes used to achieve critical surface parameters in a variety of precision optical and electronic components. As these processes remove material from the surface through mechanical and chemical interactions, they may induce a damaged layer of cracks, voids, and stressed material below the surface. This subsurface damage (SSD) can degrade the performance of a final product by creating optical aberrations due to diffraction, premature failure in oscillating components, and a reduction in the laser induced damage threshold of high energy optics. As these defects lie beneath the surface, they are difficult to detect, and while many methods are available to detect SSD, they can have notable limitations regarding sample size and type, preparation time, or can be destructive in nature. The authors tested a nondestructive method for assessing SSD that consisted of tagging the abrasive slurries used in lapping and polishing with quantum dots (nano-sized fluorescent particles). Subsequent detection of fluorescence on the processed surface is hypothesized to indicate SSD. Quantum dots that were introduced to glass surfaces during the lapping process were retained through subsequent polishing and cleaning processes. The quantum dots were successfully imaged by both wide field and confocal fluorescence microscopy techniques. The detected fluorescence highlighted features that were not observable with optical or interferometric microscopy. Atomic force microscopy and additional confocal microscope analysis indicate that the dots are firmly embedded in the surface but do not appear to travel deep into fractures beneath the surface. Etching of the samples exhibiting fluorescence confirmed that SSD existed. SSD-free samples exposed to quantum dots did not retain the dots in their surfaces, even when polished in the presence of quantum dots.

  3. Physical and mechanical properties of microcrystalline cellulose prepared from local agricultural residues

    International Nuclear Information System (INIS)

    El-Sakhawy, M.M.; Hassan, M.L.

    2005-01-01

    Microcrystalline cellulose (MCC) was prepared from local agricultural residues, namely, bagasse, rice straw, and cotton stalks bleached pulps. Hydrolysis of bleached pulps was carried out using hydrochloric or sulfuric acid to study the effect of the acid used on the properties of produced microcrystalline cellulose such as degree of polymerization (DP), crystallinity index (CrI), crystallite size, bulk density, particle size, and thermal stability. The mechanical properties of tablets made from microcrystalline cellulose of the different agricultural residues were tested and compared to commercial grade MCC. The use of rice straw pulp in different proportions as a source of silica to prepare silicified microcrystalline cellulose (SMCC) was carried out. The effect of the percent of silica on the mechanical properties of tablets before and after wet granulation was tested

  4. Preparation, characterization and mechanical properties of rare-earth-based nanocomposites

    Directory of Open Access Journals (Sweden)

    Musbah S.S.

    2012-01-01

    Full Text Available This study reports research related to different preparation methods and characterization of polymer nanocomposites for optical applications. The Eu-ion doped Gd2O3 nanophosphor powder with different nanoparticle content was embedded in the matrix of PMMA. Preparation was carried out by mixing molding (bulk, electrospinning (nanofibers and solution casting (thin films with neat particles and particles coated with AMEO silane. Among the pros and cons for proposed methods, the mixing molding enables to avoid solvent use while the best deagglomeration and nanoparticle distribution is gained using the electrospinning method. The results of dynamic mechanical analysis (DMA and nanoindentation revealed that the storage modulus of the composites was higher than that of pure PMMA and increased with nanophosphor content. Surface modification of particles improved the mechanical properties of nanocomposites.

  5. Physical and mechanical properties of microcrystalline cellulose prepared from local agricultural residues

    Energy Technology Data Exchange (ETDEWEB)

    El-Sakhawy, M M; Hassan, M L [Cellulose and Paper Dept., National Research Center, Dokki, Cairo (Egypt)

    2005-07-01

    Microcrystalline cellulose (MCC) was prepared from local agricultural residues, namely, bagasse, rice straw, and cotton stalks bleached pulps. Hydrolysis of bleached pulps was carried out using hydrochloric or sulfuric acid to study the effect of the acid used on the properties of produced microcrystalline cellulose such as degree of polymerization (DP), crystallinity index (CrI), crystallite size, bulk density, particle size, and thermal stability. The mechanical properties of tablets made from microcrystalline cellulose of the different agricultural residues were tested and compared to commercial grade MCC. The use of rice straw pulp in different proportions as a source of silica to prepare silicified microcrystalline cellulose (SMCC) was carried out. The effect of the percent of silica on the mechanical properties of tablets before and after wet granulation was tested.

  6. Laser polishing of 3D printed mesoscale components

    International Nuclear Information System (INIS)

    Bhaduri, Debajyoti; Penchev, Pavel; Batal, Afif; Dimov, Stefan; Soo, Sein Leung; Sten, Stella; Harrysson, Urban; Zhang, Zhenxue; Dong, Hanshan

    2017-01-01

    Highlights: • Process optimisation for laser polishing novel 3D printed SS316L parts. • Evaluating the effects of key polishing parameters on SS316L surface roughness. • Detailed spectroscopic analysis of oxide layer formation due to laser polishing. • Comparative surface integrity analysis of SS parts polished in air and argon. • A maximum reduction in roughness of over 94% achieved at optimised polishing settings. - Abstract: Laser polishing of various engineered materials such as glass, silica, steel, nickel and titanium alloys, has attracted considerable interest in the last 20 years due to its superior flexibility, operating speed and capability for localised surface treatment compared to conventional mechanical based methods. The paper initially reports results from process optimisation experiments aimed at investigating the influence of laser fluence and pulse overlap parameters on resulting workpiece surface roughness following laser polishing of planar 3D printed stainless steel (SS316L) specimens. A maximum reduction in roughness of over 94% (from ∼3.8 to ∼0.2 μm S_a) was achieved at the optimised settings (fluence of 9 J/cm"2 and overlap factors of 95% and 88–91% along beam scanning and step-over directions respectively). Subsequent analysis using both X-ray photoelectron spectroscopy (XPS) and glow discharge optical emission spectroscopy (GDOES) confirmed the presence of surface oxide layers (predominantly consisting of Fe and Cr phases) up to a depth of ∼0.5 μm when laser polishing was performed under normal atmospheric conditions. Conversely, formation of oxide layers was negligible when operating in an inert argon gas environment. The microhardness of the polished specimens was primarily influenced by the input thermal energy, with greater sub-surface hardness (up to ∼60%) recorded in the samples processed with higher energy density. Additionally, all of the polished surfaces were free of the scratch marks, pits, holes, lumps

  7. Laser polishing of 3D printed mesoscale components

    Energy Technology Data Exchange (ETDEWEB)

    Bhaduri, Debajyoti, E-mail: debajyoti.bhaduri@gmail.com [Department of Mechanical Engineering, School of Engineering, University of Birmingham, Edgbaston, Birmingham, B15 2TT (United Kingdom); Penchev, Pavel; Batal, Afif; Dimov, Stefan; Soo, Sein Leung [Department of Mechanical Engineering, School of Engineering, University of Birmingham, Edgbaston, Birmingham, B15 2TT (United Kingdom); Sten, Stella; Harrysson, Urban [Digital Metal, Höganäs AB, 263 83 Höganäs (Sweden); Zhang, Zhenxue; Dong, Hanshan [School of Metallurgy and Materials, University of Birmingham, Edgbaston, Birmingham, B15 2TT (United Kingdom)

    2017-05-31

    Highlights: • Process optimisation for laser polishing novel 3D printed SS316L parts. • Evaluating the effects of key polishing parameters on SS316L surface roughness. • Detailed spectroscopic analysis of oxide layer formation due to laser polishing. • Comparative surface integrity analysis of SS parts polished in air and argon. • A maximum reduction in roughness of over 94% achieved at optimised polishing settings. - Abstract: Laser polishing of various engineered materials such as glass, silica, steel, nickel and titanium alloys, has attracted considerable interest in the last 20 years due to its superior flexibility, operating speed and capability for localised surface treatment compared to conventional mechanical based methods. The paper initially reports results from process optimisation experiments aimed at investigating the influence of laser fluence and pulse overlap parameters on resulting workpiece surface roughness following laser polishing of planar 3D printed stainless steel (SS316L) specimens. A maximum reduction in roughness of over 94% (from ∼3.8 to ∼0.2 μm S{sub a}) was achieved at the optimised settings (fluence of 9 J/cm{sup 2} and overlap factors of 95% and 88–91% along beam scanning and step-over directions respectively). Subsequent analysis using both X-ray photoelectron spectroscopy (XPS) and glow discharge optical emission spectroscopy (GDOES) confirmed the presence of surface oxide layers (predominantly consisting of Fe and Cr phases) up to a depth of ∼0.5 μm when laser polishing was performed under normal atmospheric conditions. Conversely, formation of oxide layers was negligible when operating in an inert argon gas environment. The microhardness of the polished specimens was primarily influenced by the input thermal energy, with greater sub-surface hardness (up to ∼60%) recorded in the samples processed with higher energy density. Additionally, all of the polished surfaces were free of the scratch marks, pits, holes

  8. Composite adaptive control of belt polishing force for aero-engine blade

    Science.gov (United States)

    Zhsao, Pengbing; Shi, Yaoyao

    2013-09-01

    The existing methods for blade polishing mainly focus on robot polishing and manual grinding. Due to the difficulty in high-precision control of the polishing force, the blade surface precision is very low in robot polishing, in particular, quality of the inlet and exhaust edges can not satisfy the processing requirements. Manual grinding has low efficiency, high labor intensity and unstable processing quality, moreover, the polished surface is vulnerable to burn, and the surface precision and integrity are difficult to ensure. In order to further improve the profile accuracy and surface quality, a pneumatic flexible polishing force-exerting mechanism is designed and a dual-mode switching composite adaptive control(DSCAC) strategy is proposed, which combines Bang-Bang control and model reference adaptive control based on fuzzy neural network(MRACFNN) together. By the mode decision-making mechanism, Bang-Bang control is used to track the control command signal quickly when the actual polishing force is far away from the target value, and MRACFNN is utilized in smaller error ranges to improve the system robustness and control precision. Based on the mathematical model of the force-exerting mechanism, simulation analysis is implemented on DSCAC. Simulation results show that the output polishing force can better track the given signal. Finally, the blade polishing experiments are carried out on the designed polishing equipment. Experimental results show that DSCAC can effectively mitigate the influence of gas compressibility, valve dead-time effect, valve nonlinear flow, cylinder friction, measurement noise and other interference on the control precision of polishing force, which has high control precision, strong robustness, strong anti-interference ability and other advantages compared with MRACFNN. The proposed research achieves high-precision control of the polishing force, effectively improves the blade machining precision and surface consistency, and

  9. Design and fabrication of a mechanical alloying system for preparing intermetallic, nanocrystalline, amorphous and quasicrystalline compounds

    International Nuclear Information System (INIS)

    Bonifacio M, J.; Iturbe G, J.L.; Castaneda J, G.

    2002-01-01

    In this work a grinding system was designed and fabricated which allowed to improve the operation conditions in time, frequency, temperature and selection of the grinding media and that allow the contamination decrease of the compounds. By means of this method of mechanical alloying new metallic compounds can be produced, starting from elemental powders, with fine and controlled microstructures. These compounds prepared by this method are going to be used as materials for the hydrogen storage. (Author)

  10. What the cerveau isolé preparation tells us nowadays about sleep-wake mechanisms?

    Science.gov (United States)

    Gottesmann, C

    1988-01-01

    The intercollicular transected preparation opened a rich field for investigations of sleep-wake mechanisms. Initial results showed that brain stem ascending influences are essential for maintaining an activated cortex. It was subsequently shown that the forebrain also develops activating influences, since EEG desynchronization of the cortex reappears in the chronic cerveau isolé preparation, and continuous or almost continuous theta rhythm is able to occur in the acute cerveau isolé preparation. A brief "intermediate stage" of sleep occurs during natural sleep just prior to and after paradoxical sleep. It is characterized by cortical spindle bursts, hippocampal low frequency theta activity (two patterns of the acute cerveau isolé preparation) and is accompanied by a very low thalamic transmission level, suggesting a cerveau isolé-like state. The chronic cerveau isolé preparation also demonstrates that the executive processes of paradoxical sleep are located in the lower brain stem, while the occurrence of this sleep stage seems to be modulated by forebrain structures.

  11. Large coercivity in nanocrystalline TbMn6Sn6 permanent magnets prepared by mechanical milling

    International Nuclear Information System (INIS)

    Zhang Hongwei; Zhao Tongyun; Zhang Jian; Rong Chuanbing; Zhang Shaoying; Shen Baogen; Li Lu; Zhang Ligang

    2003-01-01

    Isotropic TbMn 6 Sn 6 was prepared by mechanical milling and subsequent annealing. Although the crystalline grain size was a little larger than 15 nm, no remanence enhancement resulting from intergrain exchange coupling was observed. The coercivity μ 0 H c = 0.96 T at 293 K was much larger than that expected from magnetocrystalline anisotropy. The smallest effective anisotropy constant is suggested to be 0.25 MJ m -3 when the coercivity mechanism is controlled by coherent rotation of magnetization in a single-domain grain. The contributions of shape anisotropy and magnetoelastic anisotropy are considered in order to explain the large coercivity in the magnets

  12. Production of rare earth polishing powders in Russia

    International Nuclear Information System (INIS)

    Kosynkin, V.D.; Ivanov, E.N.; Kotrekhov, V.A.; Shtutza, M.G.; Grabko, A.I.

    1998-01-01

    Full text: Russia is a potent producer of polishing powders made of rare earth material presented as an extensive and well developed base. Considering the reserves, the facilities predisposition and the polishing agent (cerium dioxide) content the chief mineral source is loparite, apatite and monazite. The production of rare earth polishing powders is based on specially developed continuous technological processes, corrosion-proof equipment, ensuring a high and stable production quality. A special attention is paid to the radiation safety of the powders. The initial material for the rare earth polishing powders based on loparite is the fusion cake of rare earth chlorides obtained at that mineral chlorination. The technology of the polishing powder production from the REE fusion cake includes the following stages: dissolution of the REE fusion cake chlorides; - thorough cleaning of the REE fusion cake chlorides from radioactive and non-rare-earth impurities; chemical precipitation of REE carbonates, obtaining middlings with proper material and granulometric composition, thermal treatment of precipitated carbonates followed with the operations of drying and roasting; classification of roasted oxides, obtaining end products - polishing powders. The production of fluorine-containing powders includes the stage of their fluorination after the stage of carbonate precipitation. The stabilizing doping can be introduced both into the middlings during one of the technological process of powders manufacturing and into the end product. Rare earth polishing powders are manufactured in Russia by the Share Holding Company 'Chepetz Mechanical Plant' (ChMP Co.), the city of Glasov. The plant produces a number of polishing materials, such as; polishing powder Optinol, containing at least 50% by mass of cerium dioxide, used in the mass production of optical and other articles; polishing powder Optinol-10 with doping to improve the sedimentary and aggregate stability of the solid phase

  13. The Preparation for the Cooperativisation of the Polish Rural Youth Not Included in School Teaching during the Interwar Period (1918–1939 [Przysposobienie spółdzielcze wiejskiej młodzieży pozaszkolnej w Polsce w okresie międzywojennym (1918–1939

    Directory of Open Access Journals (Sweden)

    Elżbieta MAGIERA

    2017-11-01

    Full Text Available The output of the XXth century Polish cooperative movement can be considered in ideological, organisational, economic, social and educational terms. The cooperative movement had a significant effect on the educational and propagating activities for both adults and school children. The cooperative movement criticized egoism and the pursuit of profit, taught cooperative forms of work, mutual help, and solidarity as well as providing the basic necessities for the poor. It supported the family and the education of children, young people and adults. It propagated the development of student organizations, the cooperative education and upbringing through taking cooperation into consideration in curricula. Cooperative education was created at the Polish cooperative movement’s initiative. It raised the level of the farmer’s knowledge and skills. It was also conducive to their activation. It's educational and upbringing activities disseminated the idea of the cooperative. They also spread the theoretical and practical knowledge which was necessary to found and run cooperative institutions. The preparation for cooperativisaton was organised among young people and adults in both urban and rural areas. It was aimed at raising awareness and educating the youth not included in the school teaching in accordance with the idea of cooperation, establishing contact and cooperation with cooperatives as well as shaping the characters of the rural youth. Youth organisations played an important role in the teaching of cooperation for young people not included in the school teaching. They propagated social assistance, self-education, preparation for cooperation and prepared the young generation for participating in the cooperative movement of adults. Moreover, the preparation for cooperation among the rural youth was included in the agricultural education which was a common method of spreading amongst young people the necessary skills for agriculture. It also

  14. Polish Toxic Currency Options

    Directory of Open Access Journals (Sweden)

    Waldemar Gontarski

    2009-06-01

    Full Text Available Toxic currency options are defined on the basis of the opposition to the nature (essence of an option contract, which is justified in terms of norms founded on the general law clause of characteristics (nature of a relation (which represents an independent premise for imposing restrictions on the freedom of contracts. So-understood toxic currency options are unlawful. Indeed they contravene iuris cogentis regulations. These include for instance option contracts, which are concluded with a bank, if the bank has not informed about option risk before concluding the contract; or the barrier options, which focus only on the protection of bank’s interests. Therefore, such options may appear to be invalid. Therefore, performing contracts for toxic currency options may be qualified as a criminal mismanagement. For the sake of security, the manager should then take into consideration filing a claim for stating invalidity (which can be made in a court verdict. At the same time, if the supervisory board member in a commercial company, who can also be a subject to mismanagement offences, commits an omission involving lack of reaction (for example, if he/she fails to notify of the suspected offence committed by the management board members acting to the company’s detriment when the management board makes the company conclude option contracts which are charged with absolute invalidity the supervisory board member so acting may be considered to act to the company’s detriment. In the most recent Polish jurisprudence and judicature the standard of a “good host” is treated to be the last resort for determining whether the manager’s powers resulting from criminal regulations were performed. The manager of the exporter should not, as a rule, issue any options. Issuing options always means assuming an obligation. In the case of currency put options it is an absolute obligation to purchase a given amount in euro at exchange rate set in advance. On the

  15. Electron beam crosslinked gels-Preparation, characterization and their effect on the mechanical, dynamic mechanical and rheological properties of rubbers

    International Nuclear Information System (INIS)

    Mitra, Suman; Chattopadhyay, Santanu; Sabharwal, Sunil; Bhowmick, Anil K.

    2010-01-01

    Electron beam (EB) crosslinked natural rubber (NR) gels were prepared by curing NR latex with EB irradiation over a range of doses from 2.5 to 20 kGy using butyl acrylate as sensitizer. The NR gels were systematically characterized by solvent swelling, dynamic light scattering, mechanical and dynamic mechanical properties. These gels were introduced in virgin NR and styrene butadiene rubber (SBR) matrices at 2, 4, 8 and 16 phr concentration. Addition of the gels improved the mechanical and dynamic mechanical properties of NR and SBR considerably. For example, 16 phr of 20 kGy EB-irradiated gel-filled NR showed a tensile strength of 3.53 MPa compared to 1.85 MPa of virgin NR. Introduction of gels in NR shifted the glass transition temperature to a higher temperature. A similar effect was observed in the case of NR gel-filled SBR systems. Morphology of the gel-filled systems was studied with atomic force microscopy. The NR gels also improved the processability of the virgin rubbers greatly. Both the shear viscosity and the die swell values of EB-irradiated gel-filled NR and SBR were lower than their virgin counterparts as investigated by capillary rheometer.

  16. Electron beam crosslinked gels-Preparation, characterization and their effect on the mechanical, dynamic mechanical and rheological properties of rubbers

    Energy Technology Data Exchange (ETDEWEB)

    Mitra, Suman; Chattopadhyay, Santanu [Rubber Technology Centre, Indian Institute of Technology, Kharagpur 721302 (India); Sabharwal, Sunil [Radiation Technology Development Section, Bhabha Atomic Research Center, Trombay, Mumbai 400085 (India); Bhowmick, Anil K., E-mail: anilkb@rtc.iitkgp.ernet.i [Rubber Technology Centre, Indian Institute of Technology, Kharagpur 721302 (India)

    2010-03-15

    Electron beam (EB) crosslinked natural rubber (NR) gels were prepared by curing NR latex with EB irradiation over a range of doses from 2.5 to 20 kGy using butyl acrylate as sensitizer. The NR gels were systematically characterized by solvent swelling, dynamic light scattering, mechanical and dynamic mechanical properties. These gels were introduced in virgin NR and styrene butadiene rubber (SBR) matrices at 2, 4, 8 and 16 phr concentration. Addition of the gels improved the mechanical and dynamic mechanical properties of NR and SBR considerably. For example, 16 phr of 20 kGy EB-irradiated gel-filled NR showed a tensile strength of 3.53 MPa compared to 1.85 MPa of virgin NR. Introduction of gels in NR shifted the glass transition temperature to a higher temperature. A similar effect was observed in the case of NR gel-filled SBR systems. Morphology of the gel-filled systems was studied with atomic force microscopy. The NR gels also improved the processability of the virgin rubbers greatly. Both the shear viscosity and the die swell values of EB-irradiated gel-filled NR and SBR were lower than their virgin counterparts as investigated by capillary rheometer.

  17. Terminology extraction from medical texts in Polish.

    Science.gov (United States)

    Marciniak, Małgorzata; Mykowiecka, Agnieszka

    2014-01-01

    Hospital documents contain free text describing the most important facts relating to patients and their illnesses. These documents are written in specific language containing medical terminology related to hospital treatment. Their automatic processing can help in verifying the consistency of hospital documentation and obtaining statistical data. To perform this task we need information on the phrases we are looking for. At the moment, clinical Polish resources are sparse. The existing terminologies, such as Polish Medical Subject Headings (MeSH), do not provide sufficient coverage for clinical tasks. It would be helpful therefore if it were possible to automatically prepare, on the basis of a data sample, an initial set of terms which, after manual verification, could be used for the purpose of information extraction. Using a combination of linguistic and statistical methods for processing over 1200 children hospital discharge records, we obtained a list of single and multiword terms used in hospital discharge documents written in Polish. The phrases are ordered according to their presumed importance in domain texts measured by the frequency of use of a phrase and the variety of its contexts. The evaluation showed that the automatically identified phrases cover about 84% of terms in domain texts. At the top of the ranked list, only 4% out of 400 terms were incorrect while out of the final 200, 20% of expressions were either not domain related or syntactically incorrect. We also observed that 70% of the obtained terms are not included in the Polish MeSH. Automatic terminology extraction can give results which are of a quality high enough to be taken as a starting point for building domain related terminological dictionaries or ontologies. This approach can be useful for preparing terminological resources for very specific subdomains for which no relevant terminologies already exist. The evaluation performed showed that none of the tested ranking procedures were

  18. Initial polishing time affects gloss retention in resin composites.

    Science.gov (United States)

    Waheeb, Nehal; Silikas, Nick; Watts, David

    2012-10-01

    To determine the effect of finishing and polishing time on the surface gloss of various resin-composites before and after simulated toothbrushing. Eight representative resin-composites (Ceram X mono, Ceram X duo, Tetric EvoCeram, Venus Diamond, EsteliteSigma Quick, Esthet.X HD, Filtek Supreme XT and Spectrum TPH) were used to prepare 80 disc-shaped (12 mm x 2 mm) specimens. The two step system Venus Supra was used for polishing the specimens for 3 minutes (Group A) and 10 minutes (Group B). All specimens were subjected to 16,000 cycles of simulated toothbrushing. The surface gloss was measured after polishing and after brushing using the gloss meter. Results were evaluated using one way ANOVA, two ways ANOVA and Dennett's post hoc test (P = 0.05). Group B (10-minute polishing) resulted in higher gloss values (GV) for all specimens compared to Group A (3 minutes). Also Group B showed better gloss retention compared to Group A after simulated toothbrushing. In each group, there was a significant difference between the polished composite resins (P gloss after the simulated toothbrushing.

  19. Polish-German bilingualism at school. A Polish perspective

    Directory of Open Access Journals (Sweden)

    Pulaczewska, Hanna

    2014-03-01

    Full Text Available This article presents the institutional frames for the acquisition of Polish literacy skills in Germany and the maintenance of Polish-German bilingualism after the repatriation of bilingual children to Poland. These processes are examined in the context of recent developments in the European domestic job market. While the European Union has placed proficiency in several languages among its educational objectives, and foreign languages have been made obligatory school subjects in all member countries, the potential advantages of internal European migrations for producing high-proficiency bilinguals are being ignored. Bilingualism resulting from migration and biculturalism enjoys little social prestige in the host countries. In Germany, there is significant regional variation in how school authorities react to challenges posed by the presence of minority languages. In many cases, the linguistic potential of many second-generation migrants and re-emigrants gets largely wasted because of lacking interest and incentives from German and Polish institutions alike.

  20. MWCNTs/Cellulose Hydrogels Prepared from NaOH/Urea Aqueous Solution with Improved Mechanical Properties

    Directory of Open Access Journals (Sweden)

    Yingpu Zhang

    2015-01-01

    Full Text Available Novel high strength composite hydrogels were designed and synthesized by introducing multiwalled carbon nanotubes (MWCNTs into cellulose/NaOH/urea aqueous solution and then cross-linked by epichlorohydrin. MWCNTs were used to modify the matrix of cellulose. The structure and morphology of the hydrogels were characterized by Fourier transform infrared (FT-IR spectroscopy, high resolution transmission electron microscopy (HR-TEM, and scanning electron microscopy (SEM. The results from swelling testing revealed that the equilibrium swelling ratio of hydrogels decreased with the increment of MWCNTs content. Thermogravimetric analysis (TGA and dynamic mechanical analysis (DMA results demonstrated that the introduction of MWCNT into cellulose hydrogel networks remarkably improved both thermal and mechanical properties of the composite hydrogels. The preparation of MWCNTs modifiedcellulose-based composites with improved mechanical properties was the first important step towards the development of advanced functional materials.

  1. Microstructural and mechanical characteristics of porous iron prepared by powder metallurgy.

    Science.gov (United States)

    Capek, Jaroslav; Vojtěch, Dalibor

    2014-10-01

    The demand for porous biodegradable load-bearing implants has been increasing recently. Based on investigations of biodegradable stents, porous iron may be a suitable material for such applications. In this study, we prepared porous iron samples with porosities of 34-51 vol.% by powder metallurgy using ammonium bicarbonate as a space-holder material. We studied sample microstructure (SEM-EDX and XRD), flexural and compressive behaviors (universal loading machine) and hardness HV5 (hardness tester) of the prepared samples. Sample porosity increased with the amount of spacer in the initial mixtures. Only the pore surfaces had insignificant oxidation and no other contamination was observed. Increasing porosity decreased the mechanical properties of the samples; although, the properties were still comparable with human bone and higher than those of porous non-metallic biomaterials and porous magnesium prepared in a similar way. Based on these results, powder metallurgy appears to be a suitable method for the preparation of porous iron for orthopedic applications. Copyright © 2014 Elsevier B.V. All rights reserved.

  2. Reagentless mechanical cell lysis by nanoscale barbs in microchannels for sample preparation.

    Science.gov (United States)

    Di Carlo, Dino; Jeong, Ki-Hun; Lee, Luke P

    2003-11-01

    A highly effective, reagentless, mechanical cell lysis device integrated in microfluidic channels is reported. Sample preparation, specifically cell lysis, is a critical element in 'lab-on-chip' applications. However, traditional methods of cell lysis require purification steps or complicated fabrication steps that a simple mechanical method of lysis may avoid. A simple and effective mechanical cell lysis system is designed, microfabricated, and characterized to quantify the efficiency of cell lysis and biomolecule accessibility. The device functionality is based on a microfluidic filter region with nanostructured barbs created using a modified deep reactive ion etching process. Mechanical lysis is characterized by using a membrane impermeable dye. Three main mechanisms of micro-mechanical lysis are described. Quantitative measurements of accessible protein as compared to a chemically lysed sample are acquired with optical absorption measurements at 280 and 414 nm. At a flow rate of 300 microL min(-1) within the filter region total protein and hemoglobin accessibilities of 4.8% and 7.5% are observed respectively as compared to 1.9% and 3.2% for a filter without nanostructured barbs.

  3. Preparing high-density polymer brushes by mechanically assisted polymer assembly (MAPA)

    Science.gov (United States)

    Wu, Tao; Efimenko, Kirill; Genzer, Jan

    2001-03-01

    We introduce a novel method of modifying the surface properties of materials. This technique, called MAPA (="mechanically assisted polymer assembly"), is based on: 1) chemically attaching polymerization initiators to the surface of an elastomeric network that has been previously stretched by a certain length, Δx, and 2) growing end-anchored macromolecules using surface initiated ("grafting from") atom transfer living radical polymerization. After the polymerization, the strain is removed from the substrate, which returns to its original size causing the grafted macromolecules to stretch away from the substrate and form a dense polymer brush. We demonstrate the feasibility of the MAPA method by preparing high-density polymer brushes of poly(acryl amide), PAAm. We show that, as expected, the grafting density of the PAAm brushes can be increased by increasing Δx. We demonstrate that polymer brushes with extremely high grafting densities can be successfully prepared by MAPA.

  4. Innovative Fly Ash Geopolymer-Epoxy Composites: Preparation, Microstructure and Mechanical Properties

    Directory of Open Access Journals (Sweden)

    Giuseppina Roviello

    2016-06-01

    Full Text Available The preparation and characterization of composite materials based on geopolymers obtained from fly ash and epoxy resins are reported for the first time. These materials have been prepared through a synthetic method based on the concurrent reticulation of the organic and inorganic components that allows the formation of hydrogen bonding between the phases, ensuring a very high compatibility between them. These new composites show significantly improved mechanical properties if compared to neat geopolymers with the same composition and comparable performances in respect to analogous geopolymer-based composites obtained starting from more expensive raw material such as metakaolin. The positive combination of an easy synthetic approach with the use of industrial by-products has allowed producing novel low cost aluminosilicate binders that, thanks to their thixotropicity and good adhesion against materials commonly used in building constructions, could be used within the field of sustainable building.

  5. Sensing roughness and polish direction

    DEFF Research Database (Denmark)

    Jakobsen, Michael Linde; Olesen, Anders Sig; Larsen, Henning Engelbrecht

    2016-01-01

    As a part of the work carried out in a project supported by the Danish Council for Technology and Innovation, we have investigated the option of smoothing standard CNC-machined surfaces. In the process of constructing optical prototypes, involving custom-designed optics, the development cost...... and time consumption can become prohibitive in a research budget. Machining the optical surfaces directly is expensive and time consuming. Alternatively, a more standardized and cheaper machining method can be used, calling for the object to be manually polished. During the polishing process, the operator...... needs information about the RMS-value of the surface roughness and the current direction of the scratches introduced by the polishing process. The RMS-value indicates to the operator how far he is from the final finish, and the scratch orientation is often specified by the customer in order to avoid...

  6. Morphology and mechanical properties of PA12/plasticized starch blends prepared by high-shear extrusion

    International Nuclear Information System (INIS)

    Teyssandier, F.; Cassagnau, P.; Gérard, J.F.; Mignard, N.; Mélis, F.

    2012-01-01

    Highlights: ► High shear rate processing was found to greatly impact PA12/starch blend morphologies. ► The morphology was observed to be stable under subsequent processing conditions. ► The mechanical properties of the blends under high-shear rate were greatly improved. ► Polymer blend preparation via high-shear processing has proved to be very effective. ► Finally, polymer blends with improved mechanical properties were obtained. - Abstract: PA12/plasticized starch blends (PA12/TPS) were prepared by high-shear twin screw extruder. The morphology development and the mechanical properties of the blends were investigated as a function of the apparent shear rate. High-shear processing has proved to be an efficient method to finely disperse thermoplastic starch in polyamide 12 matrix. Blends containing TPS domains with a size at the nano-scale (R n ∼ 150 nm) homogeneously dispersed in PA12 matrix were obtained. From a modeling point of view, the variation of the droplet radius is closer to the Wu's predictions compared to the Serpe's predictions. From the basic hypothesis of these models, it can be then assumed that compatibilization between both phases occurs during the blend processing. Furthermore, this morphology of the blends has been proved to be stable after a reprocessing step in an internal mixer most likely due to either strong hydrogen bonds between the hydroxyl groups of starch and amide groups of polyamide 12 or to potentially cross reactions between macroradicals accounting for in situ formation of graft copolymers with the potential function of compatibilizers. Mechanical properties of the blends were found to be strongly dependent on the shear rate parameter of blend processing as the mechanical properties increase with shear rate. In agreement to the blend morphology, the elongation at break of the blends was greatly improved attesting of a good adhesion between both phases.

  7. Disturbance induced by surface preparation on instrumented indentation test

    International Nuclear Information System (INIS)

    Li, Yugang; Kanouté, Pascale; François, Manuel

    2015-01-01

    Surface preparation, which may induce considerable sample disturbance, plays an important role in instrumented indentation test (IIT). In this study, the sample disturbance (mainly divided into residual stresses and plastic strain) induced by the surface preparation process of instrumented indentation test specimens were investigated with both experimental tests and numerical simulations. Grazing incidence X-ray diffractions (GIXRD) and uniaxial tensile tests were conducted for characterizing the residual stresses and high plastic strain in the top surface layers of a carefully mechanically polished indentation sample, which, in the present work, is made of commercially pure titanium. Instrumented indentation tests and the corresponding finite element simulations were performed as well. For comparison, a reference sample (carefully mechanically polished & electrolytically polished) which represents the raw material was prepared and tested. Results showed that a careful mechanical polishing procedure can effectively reduce the level of residual stresses induced by this process. However, the high plastic strain in the surface region imposed by the polishing process is significant. The induced plastic strain can affect a depth up to 5 µm, which is deeper than the maximum penetration depth h max (3 µm) used for the instrumented indentation tests. In the near surface layer (in the range of depth about 350 nm), the plastic strain levels are fairly high. In the very top layer, the plastic strain was even estimated to reach more than 60%. The simultaneous use of indentation tests and numerical simulations showed that the existence of high plastic strain in the surface region will make the load vs depth (P–h) curve shift upwards, the contact hardness (H) increase and the contact stiffness (S) decrease

  8. Disturbance induced by surface preparation on instrumented indentation test

    Energy Technology Data Exchange (ETDEWEB)

    Li, Yugang, E-mail: yugang.li@utt.fr [Université de Technologie de Troyes (UTT), ICD-LASMIS, UMR CNRS 6281, 12, rue Marie Curie-CS 42060, 10010 Troyes Cedex (France); Kanouté, Pascale, E-mail: pascale.kanoute@onera.fr [Université de Technologie de Troyes (UTT), ICD-LASMIS, UMR CNRS 6281, 12, rue Marie Curie-CS 42060, 10010 Troyes Cedex (France); The French Aerospace Lab (ONERA), DMSM/MCE, 29 avenue de la Division Leclerc-BP 72, F-92322 Chatillon Cedex (France); François, Manuel, E-mail: manuel.francois@utt.fr [Université de Technologie de Troyes (UTT), ICD-LASMIS, UMR CNRS 6281, 12, rue Marie Curie-CS 42060, 10010 Troyes Cedex (France)

    2015-08-26

    Surface preparation, which may induce considerable sample disturbance, plays an important role in instrumented indentation test (IIT). In this study, the sample disturbance (mainly divided into residual stresses and plastic strain) induced by the surface preparation process of instrumented indentation test specimens were investigated with both experimental tests and numerical simulations. Grazing incidence X-ray diffractions (GIXRD) and uniaxial tensile tests were conducted for characterizing the residual stresses and high plastic strain in the top surface layers of a carefully mechanically polished indentation sample, which, in the present work, is made of commercially pure titanium. Instrumented indentation tests and the corresponding finite element simulations were performed as well. For comparison, a reference sample (carefully mechanically polished & electrolytically polished) which represents the raw material was prepared and tested. Results showed that a careful mechanical polishing procedure can effectively reduce the level of residual stresses induced by this process. However, the high plastic strain in the surface region imposed by the polishing process is significant. The induced plastic strain can affect a depth up to 5 µm, which is deeper than the maximum penetration depth h{sub max} (3 µm) used for the instrumented indentation tests. In the near surface layer (in the range of depth about 350 nm), the plastic strain levels are fairly high. In the very top layer, the plastic strain was even estimated to reach more than 60%. The simultaneous use of indentation tests and numerical simulations showed that the existence of high plastic strain in the surface region will make the load vs depth (P–h) curve shift upwards, the contact hardness (H) increase and the contact stiffness (S) decrease.

  9. Effects of Mechanical Site Preparation on Growth of Oaks Planted on Former Agricultural Fields

    Directory of Open Access Journals (Sweden)

    John D. Hodges

    2011-12-01

    Full Text Available Mechanical site preparation is frequently proposed to alleviate problematic soil conditions when afforesting retired agricultural fields. Without management of soil problems, any seedlings planted in these areas may exhibit poor growth and survival. While mechanical site preparation methods currently employed in hardwood afforestation are proven, there is a substantial void in research comparing subsoiling, bedding, and combination plowing treatments. A total of 4,320 bare-root Nuttall oak (Quercus texana Buckley, Shumard oak (Quercus shumardii Buckley, and swamp chestnut oak (Quercus michauxii Nutt. seedlings were planted in February 2008 on three Mississippi sites. All sites were of comparable soils and received above average precipitation throughout the three-year duration of the study. Four site preparation treatments were replicated at each site, with 480 seedlings planted in each of nine replications, and a total of 1,440 seedlings per species planted across all sites. Mechanical treatments were installed using 3.1 m row centers, with treatments as follows: control, subsoiling, bedding, and combination plowing. Treatment effects on seedling height, groundline diameter (GLD, and survival were analyzed. Seedlings exhibited greater height in bedded and combination plowed areas (79.7 cm to 102.7 cm and 82.6 cm to 100.1 cm, respectively compared to subsoiled or control areas (70.4 cm to 84.6 cm and 71.4 cm to 86.9 cm, respectively. Greater GLD was observed in bedded and combination plowed areas (11.9 mm to 18.4 mm and 12.2 mm to 18.3 mm, respectively compared to subsoiled or control areas (10.2 mm to 14.6 mm and 10.5 mm to 15.6 mm, respectively. Survival was high for this study (94.%, and no differences were detected among treatments.

  10. Cannabinoids cases in polish athletes

    OpenAIRE

    A Pokrywka; Z Obmiński; D Kwiatkowska; R Grucza

    2009-01-01

    The aim of this study was to investigate the number of cases and the profiles of Polish athletes who had occasionally been using marijuana or hashish throughout the period of 1998-2004, with respect to: sex, age, and discipline of sport as well as the period of testing (in- and out-of-competition). Results of the study were compared with some data reported by other WADA accredited anti-doping laboratories. Totally, 13 631 urine samples taken from Polish athletes of both sexes, aged 10-67 year...

  11. Graphite Composite Panel Polishing Fixture

    Science.gov (United States)

    Hagopian, John; Strojny, Carl; Budinoff, Jason

    2011-01-01

    The use of high-strength, lightweight composites for the fixture is the novel feature of this innovation. The main advantage is the light weight and high stiffness-to-mass ratio relative to aluminum. Meter-class optics require support during the grinding/polishing process with large tools. The use of aluminum as a polishing fixture is standard, with pitch providing a compliant layer to allow support without deformation. Unfortunately, with meter-scale optics, a meter-scale fixture weighs over 120 lb (.55 kg) and may distort the optics being fabricated by loading the mirror and/or tool used in fabrication. The use of composite structures that are lightweight yet stiff allows standard techniques to be used while providing for a decrease in fixture weight by almost 70 percent. Mounts classically used to support large mirrors during fabrication are especially heavy and difficult to handle. The mount must be especially stiff to avoid deformation during the optical fabrication process, where a very large and heavy lap often can distort the mount and optic being fabricated. If the optic is placed on top of the lapping tool, the weight of the optic and the fixture can distort the lap. Fixtures to support the mirror during fabrication are often very large plates of aluminum, often 2 in. (.5 cm) or more in thickness and weight upwards of 150 lb (68 kg). With the addition of a backing material such as pitch and the mirror itself, the assembly can often weigh over 250 lb (.113 kg) for a meter-class optic. This innovation is the use of a lightweight graphite panel with an aluminum honeycomb core for use as the polishing fixture. These materials have been used in the aerospace industry as structural members due to their light weight and high stiffness. The grinding polishing fixture consists of the graphite composite panel, fittings, and fixtures to allow interface to the polishing machine, and introduction of pitch buttons to support the optic under fabrication. In its

  12. In situ deformation and mechanical properties of bismuth telluride prepared via zone melting

    Science.gov (United States)

    Lai, Tang-Yu; Hsiao, Yu-Jen; Fang, Te-Hua

    2018-03-01

    In this study, we prepared Bi2Te3 nanostructures via zone melting and characterized their mechanical properties by nanoindentation and in situ transmission electron microscopy (TEM). The nanoindentation results revealed that a significant ‘pop-in’ phenomenon occurs under high-loading conditions with multiple dislocations and phase transitions in the material structure. Young’s modulus of the nanostructures was found to be 42.7 ± 2.56 GPa from nanoindentation measurements and 12.3 ± 0.1 GPa from in situ TEM measurements. The results of this study may be useful for the future development of Bi2Te3 thermoelectric devices via printing processes.

  13. Microstructural and magnetic behavior of nanostructured soft alloys prepared by mechanical grinding and gas atomization

    International Nuclear Information System (INIS)

    Marin, P.; Lopez, M.; Garcia-Escorial, A.; Lieblich, M.

    2007-01-01

    Nanocrystalline powder of Fe-Si-B-Cu-Nb has been obtained by means of mechanical milling of the corresponding nanocrystalline ribbons. Gas atomization technique has been used to minimize the magnetic hardening due to stress effects observed in ball-milled samples. Fe-Si-B-Cu-Nb and Fe-Si nanocrystalline samples have been prepared by gas atomization. The aim of our work is to analyse the particle size dependence of coercivity in this nanostructured alloys and to show the analogies and differences between ball-milled and gas atomized samples

  14. Curing temperature effect on mechanical strength of smokeless fuel briquettes prepared with humates

    Energy Technology Data Exchange (ETDEWEB)

    M.J. Blesa; J.L. Miranda; M.T. Izquierdo; R. Moliner; A. Arenillas; F. Rubiera [Instituto de Carboquimica (CSIC), Zaragoza (Spain)

    2003-04-01

    The effect of curing temperature on smokeless fuel briquettes has been studied by Fourier transform infrared spectroscopy (FT-IR), mass spectrometry (MS), and temperature programmed decomposition (TPD). These techniques help to predict the final properties of these briquettes which were prepared with a low-rank coal, sawdust, and olive stone as biomasses and humates as binder. The best mechanical properties are reached with both the mildest thermal curing at 95{sup o}C and the cocarbonized at 600{sup o}C of Maria coal (M2) and sawdust (S) due to the fibrous texture of sawdust. The temperature of curing causes the release of a certain amount of oxygenate structures and the decrease of the mechanical resistance. 15 refs., 7 figs., 3 tabs.

  15. Preparation of polyvinyl alcohol graphene oxide phosphonate film and research of thermal stability and mechanical properties.

    Science.gov (United States)

    Li, Jihui; Song, Yunna; Ma, Zheng; Li, Ning; Niu, Shuai; Li, Yongshen

    2018-05-01

    In this article, flake graphite, nitric acid, peroxyacetic acid and phosphoric acid are used to prepare graphene oxide phosphonic and phosphinic acids (GOPAs), and GOPAs and polyvinyl alcohol (PVA) are used to synthesize polyvinyl alcohol graphene oxide phosphonate and phosphinate (PVAGOPs) in the case of faint acidity and ultrasound irradiation, and PVAGOPs are used to fabricate PVAGOPs film, and the structure and morphology of GOPAs, PVAGOPs and PVAGOPs film are characterized, and the thermal stability and mechanical properties of PVAGOPs film are investigated. Based on these, it has been proved that GOPAs consist of graphene oxide phosphonic acid and graphene oxide phosphinic acid, and there are CP covalent bonds between them, and PVAGOPs are composed of GOPAs and PVA, and there are six-member lactone rings between GOPAs and PVA, and the thermal stability and mechanical properties of PVAGOPs film are improved effectively. Copyright © 2018 Elsevier B.V. All rights reserved.

  16. Preparation of Basalt Incorporated Polyethylene Composite with Enhanced Mechanical Properties for Various Applications

    Directory of Open Access Journals (Sweden)

    Bredikhin Pavel

    2017-01-01

    Full Text Available The present article showed the possibility of increasing the complex of mechanical properties of polyolefins with dispersed mineral fillers obtained by fine grinding of basalt rocks via ball mill processing. The composites based on dispersed basalt, which were derived from Samara rock mass (Russia with rare earth elements containing, were obtained by extrusion combining the binder and filler, followed by preparation injection-molded test samples. The study of mechanical properties of materials developed showed the possibility of a significant increase in strength characteristics of different types of polyethylene: the breaking stress at static bending for HDPE can be increasing more than 60% and the impact strength by more than 4 times. In addition the incorporation of the dispersed basalt also enhanced the thermal properties of the composites (the oxygen index of HDPE increases from 19 to 25%.

  17. Thermoplastic starch composites with TiO2 particles: Preparation, morphology, rheology and mechanical properties.

    Science.gov (United States)

    Ostafińska, A; Mikešová, J; Krejčíková, S; Nevoralová, M; Šturcová, A; Zhigunov, A; Michálková, D; Šlouf, M

    2017-08-01

    Composites of thermoplastic starch (TPS) with titanium dioxide particles (mTiO 2 ; average size 0.1μm) with very homogeneous matrix and well-dispersed filler were prepared by a two-step method, including solution casting (SC) followed by melt mixing (MM). Light and scanning electron microscopy confirmed that only the two-step procedure (SC+MM) resulted in ideally homogeneous TPS/mTiO 2 systems. The composites prepared by single-step MM contained non-plasticized starch granules and the composites prepared by single-step SC suffered from mTiO 2 agglomeration. Dynamic mechanical measurements showed an increase modulus with increasing filler concentration. In TPS containing 3wt.% of mTiO 2 the stiffness was enhanced by >40%. Further experiments revealed that the recommended addition of chitosan or the exchange of mTiO 2 for anisometric titanate nanotubes with high aspect ratio did not improve the properties of the composites. Copyright © 2017 Elsevier B.V. All rights reserved.

  18. Polish-Bulgarian-Russian, Bulgarian-Polish-Russian or Russian-Bulgarian-Polish dictionary?

    Directory of Open Access Journals (Sweden)

    Violetta Koseska-Toszewa

    2015-11-01

    Full Text Available Polish-Bulgarian-Russian, Bulgarian-Polish-Russian or Russian-Bulgarian-Polish dictionary? The trilingual dictionary (M. Duszkin, V. Koseska, J. Satoła and A. Tzoneva is being elaborated based on a working Polish-Bulgarian-Russian electronic parallel corpus authored by Maksim Duszkin, Violetta Koseska-Toszewa and Joanna Satoła-Staśkowiak, and works by A. Tzoneva. It is the first corpus comparing languages belonging to three different Slavic language groups: western, southern and eastern. Works on the dictionary are based on Gramatyka konfrontatywna bułgarsko-polska (Bulgarian-Polish confrontative grammar and the proposed there semantic-oriented interlanguage. Two types of classifiers have been introduced into the dictionary: classic and semantic. The trilingual dictionary will present a consistent and homogeneous set of facts of grammar and semantics. The Authors point out that in a traditional dictionary it is not clear for example whether aspect should be understood as imperfective / perfective form of a verb or as its meaning. Therefore in the dictionary forms and meaning are separated in a regular way. Imperfective verb form has two meanings: state and configuration of states and events culminating in state. Also perfective verb form has two meanings: event and configuration of states and events culminating in event. These meanings are described by the semantic classifiers, respectively, state and event, state1 and event1. The way of describing language units, mentioned in the article, gives a possibility to present language material (Polish, Bulgarian, Russian in any required order, hence the article’s title.

  19. In-situ photopatterning of hydrogel microarrays in polished microchips

    NARCIS (Netherlands)

    Gümüscü, B.; van den Berg, Albert; Eijkel, Jan C.T.

    2015-01-01

    We present a fabrication method which enables simple and eproducible photopatterning of micron- sized hydrogel arrays inside closed microchips. To achieve this, the glass cover of the microchip is thinned by mechanical grinding and polishing. This procedure reduces the spacing between the photomask

  20. Violation of interest-rate parity: a Polish example

    Science.gov (United States)

    Przystawa, Jerzy; Wolf, Marek

    2000-09-01

    The mechanism of the so-called “Bagsik Oscillator” is presented and discussed. In essence, it is a repeated exploitation of arbitrage opportunities that resulted from a marked departure from the interest-rate parity relationship between the local Polish currency and the western currencies.

  1. Wear characteristics of polished and glazed lithium disilicate ceramics opposed to three ceramic materials.

    Science.gov (United States)

    Saiki, Osamu; Koizumi, Hiroyasu; Akazawa, Nobutaka; Kodaira, Akihisa; Okamura, Kentaro; Matsumura, Hideo

    2016-01-01

    This study compared the wear characteristics of a heat-pressed lithium disilicate ceramic material opposed to feldspathic porcelain, a lithium disilicate glass ceramic, and zirconia materials. Ceramic plate specimens were prepared from feldspathic porcelain (EX-3 nA1B), lithium disilicate glass ceramics (e.max CAD MO1/C14), and zirconia (Katana KT 10) and then ground or polished. Rounded rod specimens were fabricated from heat-pressed lithium disilicate glass ceramic (e.max press LT A3) and then glazed or polished. A sliding wear testing apparatus was used for wear testing. Wear of glazed rods was greater than that of polished rods when they were abraded with ground zirconia, ground porcelain, polished porcelain, or polished lithium disilicate ceramics. For both glazed and polished rods, wear was greater when the rods were abraded with ground plates. The findings indicate that application of a polished surface rather than a glazed surface is recommended for single restorations made of heat-pressed lithium disilicate material. In addition, care must be taken when polishing opposing materials, especially those used in occlusal contact areas. (J Oral Sci 58, 117-123, 2016).

  2. Melting of iron nanoparticles embedded in silica prepared by mechanical milling

    International Nuclear Information System (INIS)

    Ding, Peng; Ma, Ji; Cao, Hui; Liu, Yi; Wang, Lianwen; Li, Jiangong

    2013-01-01

    Highlights: • Melting of metallic nanoparticles was studied for some eight elements. • This slim range of materials is successfully expanded to iron. • A mechanical-milled iron–silica composite is employed. • For iron particles of 15 nm in diameter, the melting point depression is 30 K. • The measured data is in agreement with our theoretical calculations. -- Abstract: For decades, experimental studies on the size-dependent melting of metals are regretfully limited to some eight archetypal examples. In this work, to expand this slim range of materials, the melting behavior of Fe nanoparticles embedded in SiO 2 prepared by using mechanical milling are investigated. Effects of factors in sample preparation on the size, isolation and thermal stability of Fe nanoparticles are systematically studied. On this basis, the size-dependent melting of Fe is successfully traced: for Fe nanoparticles with a diameter of about 15 nm, the melting point depression is 30 °C in comparison with bulk Fe, in accordance with our recent theoretical prediction

  3. Effect of heat treatment on Fe-B-Si-Nb alloy powder prepared by mechanical alloying

    Directory of Open Access Journals (Sweden)

    Rodrigo Estevam Coelho

    2005-06-01

    Full Text Available The effect of heat treatment on crystallization behavior of Fe73.5B15Si10Nb1.5 alloy powder prepared by mechanical alloying was studied. The powder samples were prepared by mechanical alloying (MA and for different milling times (1, 5, 25, 70 and 100 hours. Crystalline powders of iron, boron, silicon and niobium were sealed with tungsten carbide balls in a cylindrical vial under nitrogen atmosphere. The ball-to-powder weight ratio was 20 to 1. A Fritsch Pulverizette 5 planetary ball mill was used for MA the powders at room temperature and at 250 rpm. To study the microstructural evolution, a small amount of powder was collected after different milling times and examined by X-ray diffraction, using CuKalpha radiation (lambda = 0.15418 nm. The crystallization behavior was studied by differential thermal analysis, from 25 up to 1000 °C at a heating rate of 25 °C min-1.

  4. Cannabinoids cases in polish athletes

    Directory of Open Access Journals (Sweden)

    A Pokrywka

    2009-07-01

    Full Text Available The aim of this study was to investigate the number of cases and the profiles of Polish athletes who had occasionally been using marijuana or hashish throughout the period of 1998-2004, with respect to: sex, age, and discipline of sport as well as the period of testing (in- and out-of-competition. Results of the study were compared with some data reported by other WADA accredited anti-doping laboratories. Totally, 13 631 urine samples taken from Polish athletes of both sexes, aged 10-67 years, performing 46 disciplines of sport were tested. Cannabinoids were detected in 267 samples. Among Polish athletes the relative number of positive THC (tetrahydrocannabinol samples was one of the highest in Europe. The group of young Polish athletes (aged 16-24 years was the most THC-positive. THC-positive cases were noted more frequently in male athletes tested during out of competitions. The so-called contact sports (rugby, ice hockey, skating, boxing, badminton, body building and acrobatic sports were those sports, where the higher risk of cannabis use was observed. The legal interpretation of some positive cannabinoids results would be difficult because of some accidental and unintentional use of the narcotics by sportsmen. It was concluded that national anti-doping organizations (NADO’s, which are competent to judge whether the anti-doping rules were violated, should take into account the possibility of non-intentional doping use of cannabinoids via passive smoking of marijuana.

  5. Retraction: Graphene-SnO2 nanocomposites decorated with quantum tunneling junctions: preparation strategies, microstructures and formation mechanism.

    Science.gov (United States)

    Simpson, Anna

    2017-09-20

    Retraction of 'Graphene-SnO 2 nanocomposites decorated with quantum tunneling junctions: preparation strategies, microstructures and formation mechanism' by Qingxiu Wang et al., Phys. Chem. Chem. Phys., 2014, 16, 19351-19357.

  6. Attitudes of Polish Consumers Toward Experiential Marketing

    Directory of Open Access Journals (Sweden)

    Monika Skorek

    2017-01-01

    Full Text Available Purpose: The experience economy is a concept that can be defned as a new way of perceiving the market offer of an enterprise, focusing on the customer experience. Enterprises, both in the production and service industries, are becoming similar to one another on a massive scale, which makes it increasingly diffcult to stand out. The response to this can be to offer the consumer an unforgettable experience related to a product or service provided by a company. Methodology: This study analysed the results of qualitative research on the attitudes and opinions of Polish consumers on experience marketing. Results/fndings: The results showed that participants of the study were prepared to transition from the economy based on products or services to an economy based on experiences at a moderate level. They declared a willingness to participate in experiences offered by companies but at the same time focus on the cost and utility of them

  7. Polish students at the Académie Julian until 1919

    Directory of Open Access Journals (Sweden)

    Zgórniak, Marek

    2012-08-01

    Full Text Available The subject of the article is the presence of Polish students in the most important private artistic school in Paris in the second half of the 19thcentury. The extant records regarding the atelier for male students made it possible to compile a list of about 165 Polish painters and sculptors studying there in the period from 1880 to 1919. The text presents the criteria used when preparing the list and the diagrams show the fluctuations in registration and the number of Polish artists in particular ateliers in successive years. The observations contained in the article have a summary nature and are illustrated only with selected examples.

  8. Structural evolution and formation mechanisms of TiC/Ti nanocomposites prepared by high-energy mechanical alloying

    International Nuclear Information System (INIS)

    Gu Dongdong; Meiners, Wilhelm; Hagedorn, Yves-christian; Wissenbach, Konrad; Poprawe, Reinhart

    2010-01-01

    In this work, high-energy ball milling of a micrometre-scaled Ti and TiC powder mixture was performed to prepare TiC/Ti nanocomposites. The constituent phases and microstructural characteristics of the milled powders were studied by an x-ray diffractometer, a scanning electron microscope, an energy dispersive x-ray spectroscope and a transmission electron microscope. Formation mechanisms and theoretical basis of the microstructural development were elucidated. It showed that on increasing the applied milling time, the structures of the Ti constituent experienced a successive change from hcp (5 h) to fcc (10 h) and finally to an amorphous state (≥15 h). The hydrostatic stresses caused by the excess free volume at grain boundaries were calculated to be 3.96 and 5.59 GPa for the Ti constituent in 5 and 10 h milled powders, which was responsible for the hcp to fcc polymorphic change. The amorphization of Ti constituent was due to the large defect concentration induced by severe plastic deformation during milling. The milled powder particles underwent two stages of significant refinement at 10 and 20 h during milling. For a higher milling time above 25 h, powder characteristics and chemical compositions became stable. The competitive action and the final equilibrium between the mechanisms of fracturing and cold welding accounted for the microstructural evolution. The ball milled products were typically nanocomposite powders featured by a nanocrystalline/amorphous Ti matrix reinforced with uniformly dispersed TiC nanoparticles. The finest crystalline sizes of the Ti and TiC constituents were 17.2 nm (after 10 h milling) and 13.5 nm (after 20 h milling), respectively.

  9. Strategy for development of the Polish electricity sector

    Energy Technology Data Exchange (ETDEWEB)

    Dybowski, J. [Polish Power Grid Co., Warsaw (Poland)

    1995-12-01

    This paper represents the strategy for development of the Polish Electricity Sector dealing with specific problems which are common for all of East Central Europe. In 1990 Poland adopted a restructuring program for the entire energy sector. Very ambitious plans were changed several times but still the main direction of change was preserved. The most difficult period of transformation is featured by several contradictions which have to be balanced. Electricity prices should increase in order to cover the modernization and development program but the society is not able to take this burden in such a short time. Furthermore the new environment protection standards force the growth of capital investment program which sooner or later has to be transferred through the electricity prices. New economic mechanisms have to be introduced to the electricity sector to replace the old ones noneffective, centrally planned. This process has to follow slow management changes. Also, introduction of new electricity market is limited by those constraints. However, this process of change would not be possible without parallel governmental initiation like preparation of new energy law and regulatory frames.

  10. Mechanical and Electrical Properties of Sulfur-Containing Polymeric Materials Prepared via Inverse Vulcanization

    Directory of Open Access Journals (Sweden)

    Sergej Diez

    2017-02-01

    Full Text Available Recently, new methods have been developed for the utilization of elemental sulfur as a feedstock for novel polymeric materials. One promising method is the inverse vulcanization, which is used to prepare polymeric structures derived from sulfur and divinyl comonomers. However, the mechanical and electrical properties of the products are virtually unexplored. Hence, in the present study, we synthesized a 200 g scale of amorphous, hydrophobic as well as translucent, hyperbranched polymeric sulfur networks that provide a high thermal resistance (>220 °C. The polymeric material properties of these sulfur copolymers can be controlled significantly by varying the monomers as well as the feed content. The investigated comonomers are divinylbenzene (DVB and 1,3-diisopropenylbenzene (DIB. Plastomers with low elastic content and high shape retention containing 12.5%–30% DVB as well as low viscose waxy plastomers with a high flow behavior containing a high DVB content of 30%–35% were obtained. Copolymers with 15%–30% DIB act, on the one hand, as thermoplastics and, on the other hand, as vitreous thermosets with a DIB of 30%–35%. Results of the thermogravimetric analysis (TGA, the dynamic scanning calorimetry (DSC and mechanical characterization, such as stress–strain experiments and dynamic mechanical thermal analysis, are discussed with the outcome that they support the assumption of a polymeric cross-linked network structure in the form of hyper-branched polymers.

  11. Convergent preparation and photophysical characterization of dimaleimide dansyl fluorogens: elucidation of the maleimide fluorescence quenching mechanism.

    Science.gov (United States)

    Guy, Julia; Caron, Karine; Dufresne, Stéphane; Michnick, Stephen W; Skene, W G; Keillor, Jeffrey W

    2007-10-03

    Dimaleimide fluorogens are being developed for application to fluorescent protein labeling. In this method, fluorophores bearing two maleimide quenching groups do not fluoresce until both maleimide groups have undergone thiol addition reactions with the Cys residues of the target protein sequence [J. Am. Chem. Soc. 2005, 127, 559-566]. In this work, a new convergent synthetic route was developed that would allow any fluorophore to be attached via a linker to a dimaleimide moiety in a modular fashion. Series of dimaleimide and dansyl derivatives were thus prepared conveniently and used to elucidate the mechanism of maleimide quenching. Intersystem crossing was ruled out as a potential quenching pathway, based on the absence of a detectable triplet intermediate by laser flash photolysis. Stern-Volmer rate constants were measured with exogenous dimaleimide quenchers and found to be close to the diffusion-controlled limits, consistent with electron transfer being thermodynamically favorable. The thermodynamic feasibility of the photoinduced electron transfer (PET) quenching mechanism was verified by cyclic voltammetry. The redox potentials measured for dansyl and maleimide confirm that electron transfer from the dansyl excited state to a pendant maleimide group is exergonic and is responsible for fluorescence quenching of the fluorogens studied herein. Taking this PET quenching mechanism into account, future fluorogenic protein labeling agents will be designed with spacers of variable length and rigidity to probe the structure-property PET efficiency relationship.

  12. Rheological and mechanical properties of polypropylene prepared with multi-walled carbon nanotube masterbatch.

    Science.gov (United States)

    Shim, Young-Sun; Park, Soo-Jin

    2012-07-01

    In this study, the effects of polypropylene-grafted maleic-anhydride-treated multi-walled carbon nanotubes (PP-MWNTs) on the viscoelastic behaviors and mechanical properties of a polypropylene-(PP)-based composite system were examined. The PP-MWNT/PP composites were prepared via melt mixing with a 3:1 ratio of PP-g-MA and acid-treated MWNTs at 220 degrees C. The surface characteristics of the PP-MWNTs were confirmed via Fourier transform infrared (FTIR) spectroscopy and transmission electron microscopy (TEM). The viscoelastic behavior and mechanical properties of the PP-MWNT/PP composites were confirmed using a rheometer and an ultimate testing machine (UTM). The storage and loss moduli increased with increasing PP-MWNT content. The critical intensity stress factor (K(IC)) of the PP-MWNT/PP composites at high filler loading was also higher than that of the MWNT/PP composites. In conclusion, the viscoelastic behavior and mechanical properties of MWNT/PP can be improved by grafting MWNTs to PP-g-MA.

  13. Experimental and Numerical Study of the Influence of Substrate Surface Preparation on Adhesion Mechanisms of Aluminum Cold Spray Coatings on 300M Steel Substrates

    Science.gov (United States)

    Nastic, A.; Vijay, M.; Tieu, A.; Rahmati, S.; Jodoin, B.

    2017-10-01

    The effect of substrate surface topography on the creation of metallurgical bonds and mechanical anchoring points has been studied for the cold spray deposition of pure aluminum on 300M steel substrate material. The coatings adhesion strength showed a significant decrease from 31.0 ± 5.7 MPa on polished substrates to 6.9 ± 2.0 MPa for substrates with roughness of 2.2 ± 0.5 μm. Strengths in the vicinity of 45 MPa were reached for coatings deposited onto forced pulsed waterjet treated surfaces with roughnesses larger than 33.8 μm. Finite element analysis has confirmed the sole presence of mechanical anchoring in coating adhesion strength for all surface treatment except polished surfaces. Grit embedment has been shown to be non-detrimental to coating adhesion for the current deposited material combination. The particle deformation process during impacts has been studied through finite element analysis using the Preston-Tonks-Wallace (PTW) constitutive model. The obtained equivalent plastic strain (PEEQ), temperature, contact pressure and velocity vector were correlated to the particle ability to form metallurgical bonds. Favorable conditions for metallurgical bonding were found to be highest for particles deposited on polished substrates, as confirmed by fracture surface analysis.

  14. Chemical etching and polishing of InP

    International Nuclear Information System (INIS)

    Kurth, E.; Reif, A.; Gottschalch, V.; Finster, J.; Butter, E.

    1988-01-01

    This paper describes possibilities of several chemical preparations for the selective cleaning of InP surfaces. The investigations of the surface states after the chemical treatment were carried out by means of XPS measurements. A pre-etching with (NH 4 ) 2 S 2 O 8 :H 2 SO 4 :H 2 O and a polishing with 1% bromine in methanol produce optically smooth (100)-and (111) P surfaces free of oxides. (author)

  15. Synthesis, microstructure and mechanical properties of ceria stabilized tetragonal zirconia prepared by spray drying technique

    International Nuclear Information System (INIS)

    Sharma, S.C.; Gokhale, N.M.; Dayal, Rajiv; Lazl, Ramji

    2002-01-01

    Ceria stabilized zirconia powders with ceria concentration varying from 6 to 16 mol% were synthesized using spray drying technique. Powders were characterized for their particle size distribution and specific surface area. The dense sintered ceramics fabricated using these powders were characterized for their microstructure, crystallite size and phase composition. The flexural strength, fracture toughness and micro-hardness of sintered ceramics were measured. High fracture toughness and flexural strength were obtained for sintered bodies with 12 mol% of CeO 2 . Flexural strength and fracture toughness were dependent on CeO 2 concentration, crystallite size and phase composition of sintered bodies. Correlation of data has indicated that the transformable tetragonal phase is the key factor in controlling the fracture toughness and strength of ceramics. It has been demonstrated that the synthesis method is effective to prepare nanocrystalline tetragonal ceria stabilized zirconia powders with improved mechanical properties. Ce-ZrO 2 with 20 wt% alumina was also prepared with flexural strength, 1200 MPa and fracture toughness 9.2 MPa√m. (author)

  16. Dissociating the role of prefrontal and premotor cortices in controlling inhibitory mechanisms during motor preparation.

    Science.gov (United States)

    Duque, Julie; Labruna, Ludovica; Verset, Sophie; Olivier, Etienne; Ivry, Richard B

    2012-01-18

    Top-down control processes are critical to select goal-directed actions in flexible environments. In humans, these processes include two inhibitory mechanisms that operate during response selection: one is involved in solving a competition between different response options, the other ensures that a selected response is initiated in a timely manner. Here, we evaluated the role of dorsal premotor cortex (PMd) and lateral prefrontal cortex (LPF) of healthy subjects in these two forms of inhibition by using an innovative transcranial magnetic stimulation (TMS) protocol combining repetitive TMS (rTMS) over PMd or LPF and a single pulse TMS (sTMS) over primary motor cortex (M1). sTMS over M1 allowed us to assess inhibitory changes in corticospinal excitability, while rTMS was used to produce transient disruption of PMd or LPF. We found that rTMS over LPF reduces inhibition associated with competition resolution, whereas rTMS over PMd decreases inhibition associated with response impulse control. These results emphasize the dissociable contributions of these two frontal regions to inhibitory control during motor preparation. The association of LPF with competition resolution is consistent with the role of this area in relatively abstract aspects of control related to goal maintenance, ensuring that the appropriate response is selected in a variable context. In contrast, the association of PMd with impulse control is consistent with the role of this area in more specific processes related to motor preparation and initiation.

  17. Dissociating the role of prefrontal and premotor cortices in controlling inhibitory mechanisms during motor preparation

    Science.gov (United States)

    Duque, Julie; Labruna, Ludovica; Verset, Sophie; Olivier, Etienne; Ivry, Richard B.

    2012-01-01

    Top-down control processes are critical to select goal-directed actions in flexible environments. In humans, these processes include two inhibitory mechanisms that operate during response selection: one is involved in solving a competition between different response options, the other ensures that a selected response is initiated timely. Here, we evaluated the role of dorsal premotor cortex (PMd) and lateral prefrontal cortex (LPF) of healthy subjects in these two forms of inhibition by using an innovative transcranial magnetic stimulation (TMS) protocol combining repetitive TMS (rTMS) over PMd or LPF and a single pulse TMS (sTMS) over primary motor cortex (M1). sTMS over M1 allowed us to assess inhibitory changes in corticospinal excitability, while rTMS was used to produce transient disruption of PMd or LPF. We found that rTMS over LPF reduces inhibition associated with competition resolution whereas rTMS over PMd decreases inhibition associated with response impulse control. These results emphasize the dissociable contributions of these two frontal regions to inhibitory control during motor preparation. The association of LPF with competition resolution is consistent with the role of this area in relatively abstract aspects of control related to goal maintenance, ensuring that the appropriate response is selected in a variable context. In contrast, the association of PMd with impulse control is consistent with the role of this area in more specific processes related to motor preparation and initiation. PMID:22262879

  18. Preparation and mechanical properties of modified nanocellulose/PLA composites from cassava residue

    Directory of Open Access Journals (Sweden)

    Lijie Huang

    2018-02-01

    Full Text Available Nanocellulose was prepared by a mechanochemical method using cassava residue as a raw material and phosphoric acid as the auxiliary agent. The prepared nanocellulose was hydrophobically modified with stearic acid to improve its dispersibility. This modified nanocellulose was added to polylactic acid (PLA film-forming liquids at concentrations of 0%, 0.5%, 1.0%, 1.5% and 2.0%, and the effect of modified nanocellulose on the mechanical properties of polylactic acid (PLA films were investigated. When at least 0.5% modified nanocellulose is added, more active groups of modified nanocellulose are adsorbed onto the PLA molecular chain. Although the tensile strength of the film is only improved by 13.59%, the flexibility of the film decreases, and the elastic modulus decreases by 28.91%. When 1% modified nanocellulose is added, the modified nanocellulose and PLA are tangled together through molecular chains and they co-crystallize to form a stable network structure. The tensile strength of the nanocomposite films is enhanced by 40.03%, the elastic modulus is enhanced by 55.65%, and the flexibility of the film decreases.

  19. Preparation and mechanical properties of modified nanocellulose/PLA composites from cassava residue

    Science.gov (United States)

    Huang, Lijie; Zhang, Xiaoxiao; Xu, Mingzi; Chen, Jie; Shi, Yinghan; Huang, Chongxing; Wang, Shuangfei; An, Shuxiang; Li, Chunying

    2018-02-01

    Nanocellulose was prepared by a mechanochemical method using cassava residue as a raw material and phosphoric acid as the auxiliary agent. The prepared nanocellulose was hydrophobically modified with stearic acid to improve its dispersibility. This modified nanocellulose was added to polylactic acid (PLA) film-forming liquids at concentrations of 0%, 0.5%, 1.0%, 1.5% and 2.0%, and the effect of modified nanocellulose on the mechanical properties of polylactic acid (PLA) films were investigated. When at least 0.5% modified nanocellulose is added, more active groups of modified nanocellulose are adsorbed onto the PLA molecular chain. Although the tensile strength of the film is only improved by 13.59%, the flexibility of the film decreases, and the elastic modulus decreases by 28.91%. When 1% modified nanocellulose is added, the modified nanocellulose and PLA are tangled together through molecular chains and they co-crystallize to form a stable network structure. The tensile strength of the nanocomposite films is enhanced by 40.03%, the elastic modulus is enhanced by 55.65%, and the flexibility of the film decreases.

  20. Preparation and Dynamic Mechanical Properties at Elevated Temperatures of a Tungsten/Glass Composite

    Science.gov (United States)

    Gao, Chong; Wang, Yingchun; Ma, Xueya; Liu, Keyi; Wang, Yubing; Li, Shukui; Cheng, Xingwang

    2018-03-01

    Experiments were conducted to prepare a borosilicate glass matrix composite containing 50 vol.% tungsten and examine its dynamic compressive behavior at elevated temperatures in the range of 450-775 °C. The results show that the homogenous microstructure of the tungsten/glass composite with relative density of 97% can be obtained by hot-pressing sintering at 800 °C for 1 h under pressure of 30 MPa. Dynamic compressive testing was carried out by a separate Hopkinson pressure bar system with a synchronous device. The results show that the peak stress decreases and the composite transforms from brittle to ductile in nature with testing temperature increasing from 450 to 750 °C. The brittle-ductile transition temperature is about 500 °C. Over 775 °C, the composite loses load-bearing capacity totally because of the excessive softening of the glass phase. In addition, the deformation and failure mechanism were analyzed.

  1. Mechanical Properties of TC4 Matrix Composites Prepared by Laser Cladding

    Directory of Open Access Journals (Sweden)

    WANG Lin

    2017-06-01

    Full Text Available In order to improve the penetration performance of TC4, the direct laser deposition technology was used to prepare TC4 composite material. TA15+30% TiC powder, TA15+20%Cr3C2 powder and TA15+15%B4C powder were used as deposited materials for TC4 matrix. The micromorphology, change of hardness of the deposited coating and mechanical properties of the three composites were studied. The experimental results demonstrate that the TC4 matrix with the three kinds of materials can form a complete metallurgical bonding, and the strength of TC4-(TA15+TiC, TC4-(TA15+Cr3C2 and TC4-(TA15+B4C are higher than that of TC4 matrix materials, while the plasticity is slightly worse.

  2. Preparation and Mechanical Properties of Chitosan-graft Maleic Anhydride Reinforced with Montmorillonite

    Science.gov (United States)

    Fajrin, A.; Sari, L. A.; Rahmawati, N.; Saputra, O. A.; Suryanti, V.

    2017-02-01

    The research aims to develop biodegradable composites as bio-based plastics from chitosan. The composites were prepared via solution casting method by introducing the maleic anhydride (MAH) as grafting agent and montmorillonite (MMt) as reinforcement. The grafting process of chitosan was conducted by varying concentrations of MAH which were 10, 20, and 30% w/w. It was observed that the chitosan-graft-maleic anhydride (Cs-g-MAH) containing 10% w/w of MAH increased its tensile strength by 70%. Reinforcement material was added to the Cs-g-MAH by varying MMt concentrations, e.g. 3, 6, 9 and 12% w/w. It was noted that the presence of 9% w/w of MMt in the Cs-g-MAH gave the best mechanical properties of the Cs-g-MAH/MMt composite.

  3. Structure and magnetic properties of nanocrystalline Fe75Si25 powders prepared by mechanical alloying

    International Nuclear Information System (INIS)

    Kalita, M.P.C.; Perumal, A.; Srinivasan, A.

    2008-01-01

    Nanocrystalline Fe 75 Si 25 powders were prepared by mechanical alloying in a planetary ball mill. The evolution of the microstructure and magnetic properties during the milling process were studied by X-ray diffraction, scanning electron microscope and vibrating sample magnetometer measurements. The evolution of non-equilibrium solid solution Fe (Si) during milling was accompanied by refinement of crystallite size down to 10 nm and the introduction of high density of dislocations of the order of 10 17 m -2 . During the milling process, Fe sites get substituted by Si. This structural change and the resulting disorder are reflected in the lattice parameters and average magnetic moment of the powders milled for various time periods. A progressive increase of coercivity was also observed with increasing milling time. The increase of coercivity could be attributed to the introduction of dislocations and reduction of powder particle size as a function of milling time

  4. Surface geometry of three packable and one hybrid composite after polishing.

    Science.gov (United States)

    Jung, Martin; Bruegger, Hilka; Klimek, Joachim

    2003-01-01

    This study evaluated the surface quality of four composite materials after polishing with six different polishing techniques. Eighty specimens were made using three packable composites (Definite/Degussa, SureFil/ Dentsply and Solitaire/Heraeus-Kulzer) and one hybrid composite (Herculite XRV/Kerr). Five specimens of each material were polished using flexible Sof-Lex discs. The remaining 75 specimens of each composite were prepared using three finishing protocols: a single 30 microm diamond (n = 25), two finishing diamonds (30/20 microm; n = 25) and a 30 microm diamond followed by a tungsten carbide finishing bur (n = 25). Final polishing of each of the three finishing groups was accomplished with SuperBuff, Diafix-oral, OneGloss, Astropol and HaWe Composite Polishers (n = 5, each). Surface roughness was evaluated quantitatively by laser-stylus profilometry. Average roughness (R(a)) was calculated; statistical analysis of the data was performed with two-way ANOVA and Scheffé post-hoc tests. The polished surfaces were examined qualitatively by SEM. The results showed significant effects on surface roughness from the different composites (p = 0.011) and polishing systems (p < 0.001). After polishing, the Solitaire surfaces (R(a) = 0.72 microm) were smoother than Definite (R(a) = 0.87 microm) and SureFil (R(a) = 0.89 microm) and significantly smoother than Herculite (R(a) = 0.92 microm; p = 0.011). Three of the polishing methods (SuperBuff, Diafix-oral and Astropol) achieved lower R(a)-values than Sof-Lex discs. The polishing quality of the one-step systems SuperBuff and Diafix-oral was strongly affected by the initial finishing protocol.

  5. Preparation and mechanism of the sintered bricks produced from Yellow River silt and red mud

    International Nuclear Information System (INIS)

    He, Hongtao; Yue, Qinyan; Su, Yuan; Gao, Baoyu; Gao, Yue; Wang, Jingzhou; Yu, Hui

    2012-01-01

    Highlights: ► The best condition was red mud content of 40% and sintering at 1050 °C for 2 h. ► Bricks’ weight loss was caused by the removal of absorbed water and crystal water. ► Bricks’ sintering shrinkage depended on the sodium and iron compounds of red mud. ► Sintering can strengthen bricks and decrease leaching concentration of toxic metal. - Abstract: The preparation, characteristics and mechanisms of sintered bricks manufactured by Yellow River silt and red mud were studied. The sintering shrinkage, weight loss on ignition, water absorption and compressive strength were tested to determine the optimum preparation condition. Sintering mechanisms were discussed through linear regression analysis. Crystalline components of raw materials and bricks were analyzed by X-ray diffraction. Leaching toxicity of raw materials and bricks were measured according to sulphuric acid and nitric acid method. Radiation safety of the sintered bricks was characterized by calculating internal exposure index and external exposure index. The results showed that at the chosen best parameters (red mud content of 40%, sintering temperature of 1050 °C and sintering time of 2 h), the best characteristics of sintered bricks could be obtained. The weight loss on ignition of sintered bricks was principally caused by the removal of absorbed water and crystal water. The sintering shrinkage of sintered bricks mainly depended on sodium compounds and iron compounds of red mud. The sintering process made some components of raw materials transform into other crystals having better thermostability. Besides, the leaching toxicity and radioactivity index of sintered bricks produced under the optimum condition were all below standards.

  6. Preparation, Characterization and Analysis of Fouling Mechanisms of TiO2- Embedded PVDF Membranes

    Directory of Open Access Journals (Sweden)

    Yoones Jafarzadeh

    2017-01-01

    Full Text Available Titanium dioxide (TiO2-embedded polyvinylidene fluoride (PVDF mixed matrix membranes were prepared through a nonsolvent induced phase separation (NIPS method. The structure of the membranes was characterized by FESEM, EDX, water drop contact angle measurement, pure water flux and mean pore radius analysis. The results showed that the prepared membranes had asymmetric structures with macro-voids and the presence of TiO2 nanoparticles increased the size of macro-voids. Moreover, pure water flux increased from 41 kg/m2h to 162 kg/m2h the content of TiO2 nanoparticles increased from 1 wt% to 5 wt% as embedded membrane. The contact angle dropped from 100° for 1 wt% TiO2- embedded membrane to 69° for 5 wt% TiO2-embedded membrane, showing that the hydrophilicity of membranes increased by addition of inorganic TiO2 nanoparticles. The fouling behavior oftheprepared mixed matrix membranes was studied in filtration process of 1% humic acid solution. The results showed that fouling resistance of the membranes increased with higher content of TiO2 nanoparticles. The results of classic fouling modeling of membranes showed that for 2 and 5 wt% TiO2-embedded membranes the best fit of the data occurred with the intermediate blockage model whereas cake formation model was the dominant mechanism for other membranes. Moreover, the analysis of fouling mechanisms by combined models showed that cake filtration-intermediate blockage model was in good agreement with the experimental data for all membranes. Finally, the results showed that the rejection of membranes increased with the addition of TiO2 nanoparticles, and then decreased.

  7. Porous poly(vinyl alcohol)/sepiolite bone scaffolds: Preparation, structure and mechanical properties

    International Nuclear Information System (INIS)

    Killeen, Derek; Frydrych, Martin; Chen Biqiong

    2012-01-01

    Porous poly(vinyl alcohol) (PVA)/sepiolite nanocomposite scaffolds containing 0–10 wt.% sepiolite were prepared by freeze-drying and thermally crosslinked with poly(arylic acid). The microstructure of the obtained scaffolds was characterised by scanning electron microscopy and micro-computed tomography, which showed a ribbon and ladder like interconnected structure. The incorporation of sepiolite increased the mean pore size and porosity of the PVA scaffold as well as the degree of anisotropy due to its fibrous structure. The tensile strength, modulus and energy at break of the PVA solid material that constructed the scaffold were found to improve with additions of sepiolite by up to 104%, 331% and 22% for 6 wt.% clay. Such enhancements were attributed to the strong interactions between the PVA and sepiolite, the good dispersion of sepiolite nanofibres in the matrix and the intrinsic properties of the nanofibres. However, the tensile properties of the PVA scaffold deteriorated in the presence of sepiolite because of the higher porosity, pore size and degree of anisotropy. The PVA/sepiolite nanocomposite scaffold containing 6 wt.% sepiolite was characterised by an interconnected structure, a porosity of 89.5% and a mean pore size of 79 μm and exhibited a tensile strength of 0.44 MPa and modulus of 14.9 MPa, which demonstrates potential for this type of materials to be further developed as bone scaffolds. - Highlights: ► Novel PAA-crosslinked PVA/sepiolite nanocomposite scaffolds were prepared. ► They were highly porous with interconnected structures and exhibited good mechanical properties. ► The effects of sepiolite nanofibres on structure and properties of the scaffolds were investigated. ► Sepiolite nanofibres improved the mechanical properties of the solid material significantly.

  8. Preparation and mechanical properties of unidirectional boron nitride fibre reinforced silica matrix composites

    International Nuclear Information System (INIS)

    Li, Duan; Zhang, Chang-Rui; Li, Bin; Cao, Feng; Wang, Si-Qing

    2012-01-01

    Highlights: → BN fibres hardly degrade when exposed at elevated temperatures. → Few researches have related to BN f /SiO 2 composites. → BN f /SiO 2 composites have fine high-temperature mechanical properties. → Self-healing properties of fused SiO 2 and B 2 O 3 may contribute to the properties. -- Abstract: The unidirectional BN f /SiO 2 composites were prepared via sol-gel method, and the structure, composition and mechanical properties were studied. The results show that the composites consist of BN fibres and α-cristobalite matrix probably as well as the interface phases of Si 3 N 4 and B 2 O 3 . The composites have a density of 1.70 g cm -3 and an open porosity of 20.8%. The average flexural strength, elastic modulus and fracture toughness at room temperature are 51.2 MPa, 23.2 GPa and 1.46 MPa m 1/2 , respectively. The composites show a very plane fracture surface with practically no pulled-out fibres. The mechanical properties of BN f /SiO 2 composites at 300-1000 o C are desirable, with the maximum flexural strength and residual ratio being 80.2 MPa and 156.8% at 500 o C, respectively, while it is a sharply reduced trend as for SiO 2f /SiO 2 composites. The high thermal stability of BN fibres and self-healing properties caused by the fused SiO 2 and B 2 O 3 enable the composites fine high-temperature mechanical properties.

  9. Polish energy-system modernisation

    International Nuclear Information System (INIS)

    Drozdz, M.

    2003-01-01

    The Polish energy-system needs intensive investments in new technologies, which are energy efficient, clean and cost effective. Since the early 1990s, the Polish economy has had practically full access to modern technological devices, equipment and technologies. Introducing new technologies is a difficult task for project teams, constructors and investors. The author presents a set of principles for project teams useful in planning and energy modernisation. Several essential features are discussed: Energy-efficient appliances and systems; Choice of energy carriers, media and fuels; Optimal tariffs, maximum power and installed power; Intelligent, integrated, steering systems; Waste-energy recovery; Renewable-energy recovery. In practice there are several difficulties connected with planning and realising good technological and economic solutions. The author presents his own experiences of energy-system modernisation of industrial processes and building new objects. (Author)

  10. Energy savings in Polish buildings

    Energy Technology Data Exchange (ETDEWEB)

    Markel, L.C.; Gula, A.; Reeves, G.

    1995-12-31

    A demonstration of low-cost insulation and weatherization techniques was a part of phase 1 of the Krakow Clean Fossil Fuels and Energy Efficient Project. The objectives were to identify a cost-effective set of measures to reduce energy used for space heating, determine how much energy could be saved, and foster widespread implementation of those measures. The demonstration project focused on 4 11-story buildings in a Krakow housing cooperative. Energy savings of over 20% were obtained. Most important, the procedures and materials implemented in the demonstration project have been adapted to Polish conditions and applied to other housing cooperatives, schools, and hospitals. Additional projects are being planned, in Krakow and other cities, under the direction of FEWE-Krakow, the Polish Energie Cities Network, and Biuro Rozwoju Krakowa.

  11. SAFETY PLATFORM OF POLISH TRANSPORT

    Directory of Open Access Journals (Sweden)

    Katarzyna CHRUZIK

    2016-03-01

    Full Text Available Analyzing the level of Polish transport safety culture can be seen that it is now dependent on the culture of safety management within the organization and the requirements and recommendations of law in this field for different modes of transport (air, rail, road, water. Of the four basic types of transport requirements are widely developed in the aviation, rail, and water – the sea. In order to harmonize the requirements for transport safety so it appears advisable to develop a platform for exchange of safety information for different modes of transport, and the development of good practices multimodal offering the possibility of improving Polish transport safety. Described in the publication of the proposal in addition to the alignment platform experience and knowledge in the field of transport safety in all its kinds, it can also be a tool for perfecting new operators of public transport.

  12. Polishing compound for plastic surfaces

    Science.gov (United States)

    Stowell, M.S.

    1991-01-01

    This invention is comprised of a polishing compound for plastic materials. The compound includes approximately by approximately by weight 25 to 80 parts at least one petroleum distillate lubricant, 1 to 12 parts mineral spirits, 50 to 155 parts abrasive paste, and 15 to 60 parts water. Preferably, the compound includes approximately 37 to 42 parts at least one petroleum distillate lubricant, up to 8 parts mineral spirits, 95 to 110 parts abrasive paste, and 50 to 55 parts water. The proportions of the ingredients are varied in accordance with the particular application. The compound is used on PLEXIGLAS{trademark}, LEXAN{trademark}, LUCITE{trademark}, polyvinyl chloride (PVC), and similar plastic materials whenever a smooth, clear polished surface is desired.

  13. Careers of young Polish chemists

    OpenAIRE

    Kosmulski, Marek

    2014-01-01

    Typical young Polish scientist is an alumnus of doctoral studies at the same university and department where he/she completed his/her Master degree. The career is continued by receiving a habilitation at the same university and department. Then a holder of habilitation is promoted to a tenured position at the same university and department. Detailed analysis of scientific careers of 154 recent Ph.D. recipients and of 16 habilitation candidates in chemistry from University of Warsaw is present...

  14. 19th Polish Control Conference

    CERN Document Server

    Kacprzyk, Janusz; Oprzędkiewicz, Krzysztof; Skruch, Paweł

    2017-01-01

    This volume contains the proceedings of the KKA 2017 – the 19th Polish Control Conference, organized by the Department of Automatics and Biomedical Engineering, AGH University of Science and Technology in Kraków, Poland on June 18–21, 2017, under the auspices of the Committee on Automatic Control and Robotics of the Polish Academy of Sciences, and the Commission for Engineering Sciences of the Polish Academy of Arts and Sciences. Part 1 deals with general issues of modeling and control, notably flow modeling and control, sliding mode, predictive, dual, etc. control. In turn, Part 2 focuses on optimization, estimation and prediction for control. Part 3 is concerned with autonomous vehicles, while Part 4 addresses applications. Part 5 discusses computer methods in control, and Part 6 examines fractional order calculus in the modeling and control of dynamic systems. Part 7 focuses on modern robotics. Part 8 deals with modeling and identification, while Part 9 deals with problems related to security, fault ...

  15. Thermal and dynamic mechanical characterization of thermoplastic polyurethane/organoclay nanocomposites prepared by melt compounding

    International Nuclear Information System (INIS)

    Barick, A.K.; Tripathy, D.K.

    2010-01-01

    Thermoplastic polyurethane (TPU) nanocomposites based on organically modified layered silicate (OMLS) were prepared by melt intercalation process followed by compression molding. Different percentage of organoclays was incorporated into the TPU matrix in order to examine the influence of the nanoscaled fillers on nanostructure morphology and material properties. The microscopic morphology of the nanocomposites was evaluated by wide angle X-ray diffraction (WAXD), transmission electron microscopy (TEM), and atomic force microscopy (AFM). The observation revealed that both nanoclay-polymer interactions and shear stress developed during melt mixing are responsible for the effectively organoclay dispersion in TPU matrix resulting intercalated/exfoliated morphology. Thermal stability of the nanocomposites measured by thermogravimetric analysis (TGA) was improved significantly with the addition of nanoclay. The differential scanning calorimetry (DSC) analysis reveals that melting point of the nanocomposites increased with incorporation of nanoclay. The dynamic mechanical properties of the TPU nanocomposites were analyzed using a dynamic mechanical thermal analyzer (DMTA), which indicates that the storage modulus (E'), loss modulus (E''), and glass transition temperature (T g ) are significantly increased with increasing nanoclay content.

  16. Preparation and mechanism analysis of an environment-friendly maize seed coating agent.

    Science.gov (United States)

    Zeng, Defang; Fan, Zhao; Tian, Xu; Wang, Wenjin; Zhou, Mingchun; Li, Haochuan

    2018-06-01

    Traditional seed coating agents often contain toxic ingredients, which contaminate the environment and threaten human health. This paper expounds a method of preparing a novel environment-friendly seed coating agent for maize and researches its mechanism of action. The natural polysaccharide polymer, which is the main active ingredient of this environment-friendly seed coating agent, has the characteristics of innocuity and harmlessness, and it can replace the toxic ingredients used in traditional seed coating agents. This environment-friendly seed coating agent for maize was mainly made up of the natural polysaccharide polymer and other additives. The field trials results showed that the control efficacy of Helminthosporium maydis came to 93.72%, the anti-feeding rate of cutworms came to 81.29%, and the maize yield was increased by 17.75%. Besides, the LD 50 value (half the lethal dose in rats) of this seed coating agent was 10 times higher than that of the traditional seed coating agents. This seed coating agent could improve the activity of plant protective enzymes (peroxidase, catalase and superoxidase dismutase) and increase the chlorophyll content. This seed coating agent has four characteristics of disease prevention, desinsectization, increasing yield and safety. Results of mechanism analyses showed that this seed coating agent could enhance disease control effectiveness by improving plant protective enzymes activity and increase maize yield by improving chlorophyll content. © 2017 Society of Chemical Industry. © 2017 Society of Chemical Industry.

  17. Characterization of Dispersion Strengthened Copper Alloy Prepared by Internal Oxidation Combined with Mechanical Alloying

    Science.gov (United States)

    Zhao, Ziqian; Xiao, Zhu; Li, Zhou; Zhu, Mengnan; Yang, Ziqi

    2017-11-01

    Cu-3.6 vol.% Al2O3 dispersion strengthened alloy was prepared by mechanical alloying (MA) of internal oxidation Cu-Al powders. The lattice parameter of Cu matrix decreased with milling time for powders milled in argon, while the abnormal increase of lattice parameter occurred in the air resulting from mechanochemical reactions. With a quantitative analysis, the combined method makes residual aluminum oxidized completely within 10-20 h while mechanical alloying method alone needs longer than 40 h. Lamellar structure formed and the thickness of lamellar structure decreased with milling time. The size of Al2O3 particles decreased from 46 to 22 nm after 40 h milling. After reduction, core-shell structure was found in MAed powders milled in the air. The compacted alloy produced by MAed powders milled in the argon had an average hardness and electrical conductivity of 172.2 HV and 82.1% IACS while the unmilled alloy's were 119.8 HV and 74.1% IACS due to the Al2O3 particles refinement and residual aluminum in situ oxidization.

  18. Nanostructured Al–Zn–Mg–Cu–Zr alloy prepared by mechanical alloying followed by hot pressing

    International Nuclear Information System (INIS)

    Azimi, Amin; Shokuhfar, Ali; Zolriasatein, Ashkan

    2014-01-01

    Nanostructured Al–7.8 wt% Zn–2.6 wt% Mg–2 wt% Cu–0.1 wt% Zr alloy was mechanically alloyed (MA) from elemental powders and consolidated by hot press technique. The effect of the milling time and hot pressing process on microstructure was investigated by means of X-ray diffraction measurements (XRD) and analytical and scanning electron microscopy (SEM). Furthermore mechanical properties of samples with different MA time as well as pure aluminum were investigated by microhardness and compression tests. The results show that an Al–Zn–Mg–Cu–Zr homogenous supersaturated solid solution with a crystallite size of 27 nm was obtained after 40 h of milling time. Microstructure refinement and morphological changes of powders from flake to spherical shape were observed by increasing milling time. Phase and microstructural characterization of high density bulk nanostructured samples revealed that increasing milling time up to 40 h leads to formation of MgZn 2 precipitation in the alloy matrix. With increasing milling time, density of the samples and crystalline size decrease. Significant enhancement of hardness and compressive strength is observed in the aluminum alloy by increasing milling time up to 40 h which is much higher than pure aluminum. Crystallite size refinement in pure aluminum samples from micro- to nanoscales resulted in 107% and 100% improvement in compressive strength and hardness, respectively. Furthermore the compressive strength and hardness of Al–Zn–Mg–Cu–Zr alloy nanostructured samples increased to 179% and 172%, respectively, compared to nanostructured pure Al, which was produced as reference specimen. 40 h of MA was the optimum case for preparing such an Al alloy and more milling up to 50 h led to deterioration of mechanical properties

  19. The effects of different polishing techniques on the staining resistance of CAD/CAM resin-ceramics

    Science.gov (United States)

    Demirci, Tevfik; Demirci, Gamze; Sagsoz, Nurdan Polat; Yildiz, Mehmet

    2016-01-01

    PURPOSE The purposes of this study were to evaluate the staining resistance of CAD/CAM resin-ceramics polished with different techniques and to determine the effectiveness of the polishing techniques on resin-ceramics, comparing it with that of a glazed glass-ceramic. MATERIALS AND METHODS Four different CAD/CAM ceramics (feldspathic ceramic: C-CEREC Blocs, (SIRONA) and three resin-ceramics: L-Lava Ultimate, (3M ESPE), E-Enamic, (VITA) and CS-CeraSmart, (GC)) and one light cure composite resin: ME-Clearfil Majesty Esthetic (Kuraray) were used. Only C samples were glazed (gl). Other restorations were divided into four groups according to the polishing technique: nonpolished control group (c), a group polished with light cure liquid polish (Biscover LV BISCO) (bb), a group polished with ceramic polishing kit (Diapol, EVE) (cd), and a group polished with composite polishing kit (Clearfil Twist Dia, Kuraray) (kc). Glazed C samples and the polished samples were further divided into four subgroups and immersed into different solutions: distilled water, tea, coffee, and fermented black carrot juice. Eight samples (8 × 8 × 1 mm) were prepared for each subgroup. According to CIELab system, four color measurements were made: before immersion, immersion after 1 day, after 1 week, and after 1 month. Data were analyzed with repeated measures of ANOVA (α=.05). RESULTS The highest staining resistance was found in gl samples. There was no difference among gl, kc and cd (P>.05). Staining resistance of gl was significantly higher than that of bb (PCeramic and composite polishing kits can be used for resin ceramics as a counterpart of glazing procedure used for full ceramic materials. Liquid polish has limited indications for resin ceramics. PMID:28018558

  20. Effects of different polishing techniques on the surface roughness of dental porcelains

    Directory of Open Access Journals (Sweden)

    Işil Sarikaya

    2010-02-01

    Full Text Available OBJECTIVE: The purpose of this study was to evaluate the effects of different polishing techniques on the surface roughness of dental porcelains. MATERIAL AND METHODS: Fifty-five cylindirical specimens (15x2 mm were prepared for each feldspathic (Vita VMK 95, Ceramco III and low-fusing dental porcelain (Matchmaker. Fifty-five specimens of machinable feldspathic porcelain blocks (Vitablocs Mark II, (12x14x18 mm were cut into 2-mm-thick slices (12x14 mm with low speed saw. The prepared specimens were divided into 11 groups (n=5 representing different polishing techniques including control ((C no surface treatment, glaze (G and other 9 groups that were finished and polished with polishing discs (Sof-Lex (Sl, two porcelain polishing kits (NTI (Pk, Dialite II (Di, a diamond polishing paste (Sparkle (Sp, a zirconium silicate based cleaning and polishing prophy paste (Zircate (Zr, an aluminum oxide polishing paste (Prisma Gloss (Pg, and combinations of them. The surface roughness of all groups was measured with a profilometer. The data were analyzed with a 2-way analysis of variance, and the mean values were compared by the Tukey Honestly Significant Difference test (a=0.05. RESULTS: For all porcelain material groups, the lowest Ra values were observed in Group Gl, Group Sl, Group Pk, and Group Di, which were not significantly different from each other (p>0.05.When comparing the 4 different porcelain materials, the machinable feldspathic porcelain block group (Mark II demonstrated statistically significantly less Ra values than the other porcelain materials tested (p<0.05. No significant difference was observed between the VMK 95 and Ceramco III porcelain groups (p=0.919, also these groups demonstrated the highest Ra values. CONCLUSION: Subjected to surface roughness, the surfaces obtained with polishing and/or cleaning-prophy paste materials used alone were rougher compared to the surfaces finished using Sof-lex, Dialite, and NTI polishing kit

  1. The tourism attractiveness of Polish libraries

    OpenAIRE

    Miedzińska, Magdalena; Tanaś, Sławoj

    2009-01-01

    The aim of the article is to draw the reader's attention to the tourism attractiveness of renowned Polish libraries. These have attained a tourism function due to tourism exploration and penetration, but remain in the shadow of other Polish cultural assets. The article outlines the historical geography of Polish libraries, an analysis of tourism assets and an attempt to classify and catalogue libraries in Poland.

  2. Study of the mechanical properties of stainless steel 316LN prepared by hot isostatic compression. Influence of preparation parameters

    International Nuclear Information System (INIS)

    Couturier, Raphael

    1999-01-01

    This research thesis has been performed within an R and D programme which aimed at optimising and certifying the HIP process (hot isostatic pressing) from a technological as well as metallurgical point of view. The objective has been to improve dimensional reproducibility of fabricated parts, and metallurgical properties of the dense material. Reference parts are those belonging to PWR primary circuit, and are made in cast austenitic-ferritic steel. Thus, the objective has been to show that these parts can be beneficially fabricated by powder metallurgy in austenitic grade. A mock part (a primary circuit pump wheel at the 1/2 scale) has first been fabricated by HIP, and a more complex shape generator has been designed. The author reports the determination of microstructure and mechanical characteristics of the austenitic 316LN steel produced by HIP and used to fabricate mock parts and demonstrator parts, the study of the relationship between dense material properties and fabrication parameters (temperature, pressure, consolidation time), and the analysis of the consequences of an elaboration by HIP on the 316LN steel with comparison with forged parts. After a presentation of the Powder Metallurgy elaboration technique, the author reports a bibliographical study on the precipitation at Prior Particle Boundaries (PPB), reports the study of microstructure and mechanical properties of the HIPed 316LN, and discusses the possibility of a decrease of precipitation at PPBs by adjusting powder degassing or a granulometric sorting. The last part reports the extension of the study of steel coherence to a temperature range which encompasses the primary circuit operation temperature (350 C). Resilience tests are performed as well as mechanical tests on notched axisymmetric samples. A finite element calculation of these samples allows the validation of the use of a Thomson-type model to describe the emergence of defects which are typical of a steel elaborated by powder

  3. Compound antimalarial ethosomal cataplasm: preparation, evaluation, and mechanism of penetration enhancement.

    Science.gov (United States)

    Shen, Shuo; Liu, Shu-Zhi; Zhang, Yu-Shi; Du, Mao-Bo; Liang, Ai-Hua; Song, Li-Hua; Ye, Zu-Guang

    2015-01-01

    Malaria is still a serious public health problem in some parts of the world. The problems of recurrence and drug resistance are increasingly more serious. Thus, it is necessary to develop a novel antimalarial agent. The objectives of this study were to construct a novel compound antimalarial transdermal nanosystem-ethosomal cataplasm, to investigate its characteristics and efficiency, and to systematically explore the penetration-enhancing mechanisms of ethosomal cataplasm. Artesunate-loaded ethosomes and febrifugine-loaded ethosomes were prepared, and their characteristics were evaluated. Drug-loaded ethosomes were incorporated in the matrix of cataplasm to form the compound antimalarial ethosomal cataplasm. With the help of ethosomal technology, the accumulated permeation quantity of artesunate significantly increased at 8 hours after administration, which was 1.57 times as much as that of conventional cataplasm. Soon after administration, the ethosomal cataplasm could make a large quantity of antimalarial drug quickly penetrate through skin, then the remaining drug in the ethosomal cataplasm could be steadily released. These characteristics of ethosomal cataplasm are favorable for antimalarial drugs to kill Plasmodium spp. quickly and prevent the resurgence of Plasmodium spp. As expected, the ethosomal cataplasm showed good antimalarial efficiency in this experiment. The negative conversion rates were 100% and the recurrence rates were 0% at all dosages. The mechanism of penetration enhancement of the ethosomal cataplasm was systematically explored using an optics microscope, polarization microscope, and transmission electron microscopy. The microstructure, ultrastructure, and birefringent structure in skin were observed. Data obtained in this study showed that the application of ethosomal technology to antimalarial cataplasm could improve the transdermal delivery of drug, enhance the efficacy, and facilitate practical application in clinic.

  4. Molecular modeling, FTIR spectral characterization and mechanical properties of carbonated-hydroxyapatite prepared by mechanochemical synthesis

    International Nuclear Information System (INIS)

    Youness, Rasha A.; Taha, Mohammed A.; Elhaes, Hanan; Ibrahim, Medhat

    2017-01-01

    Nanocrystalline B-type carbonate substituted hydroxyapatite (B-CHA) powder has been successively synthesized by mechanochemical method. The effect of milling times on the formation of B-CHA was investigated by Fourier transform infrared spectroscopy, X-ray diffraction technique and scanning electron microscopy. Moreover, physical as well as mechanical properties were examined as a function of milling time. Furthermore, theoretical model was presented for hydroxyapatite (HA). Semiempirical calculations at PM6 level were used to calculate thermal parameters including entropy; enthalpy; heat capacity; free energy and heat of formation in the temperature range from 200 up to 500 k. The results revealed that single phase B-CHA was successfully formed after 8 h of milling when Ball to Powder Ratio (BPR) equals to 10:1. Results revealed that entropy; enthalpy and heat capacity gradually increased as a function of temperature while, free energy and heat of formation decreased with the increasing of temperature. Comparison with higher level of theory was conducted at HF and DFT using the models HF/3-21g**; B3LYP/6-31G(d,p) and B3LYP/LANL2DZ, respectively and indicated that PM6 could be utilized with appropriate accuracy and time to study physical and thermochemical parameters for HA. - Highlights: • Preparation of Nanocrystalline B-type carbonate substituted hydroxyapatite (B-CHA) powder by mechanochemical method. • Characterization of CHA. • Semiemperical and DFT models for CHA.

  5. Microstructure and mechanical properties of Zr-Si-N films prepared by rf-reactive sputtering

    CERN Document Server

    Nose, M; Zhou, M; Mae, T; Meshii, M

    2002-01-01

    ZrN and ZrSiN films were prepared in an rf sputtering apparatus that has a pair of targets facing each other (referred to as the facing target--type rf sputtering). Films were deposited on silicon wafers without bias application or substrate heating in order to examine only the effect of silicon addition to the transition metal nitride films. The contents of zirconium, nitrogen, and silicon of the films were determined with an electron probe microanalyzer. The transmission electron microscopy studies were carried out in addition to x-ray diffraction. For the high resolution transmission electron microscopy observation, the field emission type transmission electron microscope was used, which provides a point-to-point resolution of 0.1 nm. The samples were observed both parallel and perpendicular to the film surface, which were plane and cross sectional views, respectively. In order to investigate the relationship between the mechanical properties and microstructure of films, the hardness was measured by a nano...

  6. Preparation and mechanical properties of rubber composites reinforced with carbon nanohorns.

    Science.gov (United States)

    Isshiki, Tetsuya; Hashimoto, Mikiko; Morii, Masato; Ota, Yuki; Kaneda, Kazuo; Takahashi, Hidetaka; Yudasaka, Masako; Iijima, Sumio; Okino, Fujio

    2010-06-01

    Nitrile butadiene rubber (NBR) composites with single-wall carbon nanohorns (SWNHs, or simply NHs), hole-opened NHs (h-NHs), and carbon black (CB), the most commonly used nanocarbon rubber filler, were prepared, and their mechanical properties were compared. The NBR composites with h-NHs (NBR/h-NH) showed higher tensile strength than those with NHs (NBR/NH), and the tensile strength of NBR/h-NH or NBR/NH was much greater than those of the NBR composites with CB (NBR/CB). At 5 parts per hundred of rubber (phr), the tensile stresses at break of NBR/h-NH was about 1.8 times larger than those of NBR/CB, and the strain at the break, 1.2 times larger. Similarly, at 20 phr, both the tensile strength and strain at the break of NBR/h-NH were 1.4 times larger than those of NBR/CB. NBR/NH showed the highest hardness while having the smallest specific gravity. The present results indicate that NHs and h-NHs have much superior reinforcement effects to CB for NBR rubber matrix.

  7. A multifaceted knowledge translation strategy can increase compliance with guideline recommendations for mechanical bowel preparation.

    Science.gov (United States)

    Eskicioglu, Cagla; Pearsall, Emily; Victor, J Charles; Aarts, Mary-Anne; Okrainec, Allan; McLeod, Robin S

    2015-01-01

    The successful transfer of evidence into clinical practice is a slow and haphazard process. We report the outcome of a 5-year knowledge translation (KT) strategy to increase adherence with a clinical practice guideline (CPG) for mechanical bowel preparation (MBP) for elective colorectal surgery patients. A locally tailored CPG recommending MBP practices was developed. Data on MBP practices were collected at six University of Toronto hospitals before CPG implementation as well as after two separate KT strategies. KT strategy #1 included development of the CPG, education by opinion leaders, reminder cards, and presentations of data. KT strategy #2 included selection of hospital champions, development of communities of practice, education, reminder cards, electronic updates, pre-printed standardized orders, and audit and feedback. A total of 744 patients (400 males, 344 females, mean age 57.0) were included. Compliance increased from 58.6 to 70.4% after KT strategy #1 and to 81.1% after KT strategy #2 (p < 0.001). Using a tailored KT strategy, increased compliance was observed with CPG recommendations over time suggesting that a longitudinal KT strategy is required to increase and sustain compliance with recommendations. Furthermore, different strategies may be required at different times (i.e., educational sessions initially and reminders and standardized orders to maintain adherence).

  8. Preparation, characterization, mechanical, barrier and antimicrobial properties of chitosan/PVOH/clay nanocomposites.

    Science.gov (United States)

    Giannakas, Aris; Vlacha, Maria; Salmas, Constantinos; Leontiou, Areti; Katapodis, Petros; Stamatis, Haralambos; Barkoula, Nektaria-Marianthi; Ladavos, Athanasios

    2016-04-20

    In the current study low molecular weight poly(vinylalcohol) (PVOH) was used to prepare chitosan/PVOH blends and chitosan/PVOH/montmorillonite nanocomposites via a reflux - solution - heat pressing method. The effect of PVOH content and montmorillonite type (hydrophylic vs. organically modified) on the morphology, mechanical, thermomechanical, barrier and antimicrobial properties of the obtained polymer blends and nanocomposite films was studied. Higher amounts of PVOH (20 and 30%) resulted in plasticization of the films, with an increase in the elongation at break and decrease of the stiffness and the strength while effective blending between chitosan and PVOH chains was observed based on the XRD and DMA findings. Addition of PVOH was beneficial for water and oxygen barrier properties of the obtained films while it did not influence the antimicrobial activity of films against the growth of Escherichia coli. Intercalated structures were obtained after the addition of hydrophilic and organo-modified clays leading into stiffening of the nano-modified films and enhancement of their barrier and antimicrobial properties. Copyright © 2015 Elsevier Ltd. All rights reserved.

  9. The role of mechanical bowel preparation for colonic resection and anastomosis: an experimental study.

    Science.gov (United States)

    Feres, O; Monteiro dos Santos, J C; Andrade, J I

    2001-11-01

    To evaluate the effect of mechanical bowel preparation (MBP) on colonic resection and anastomosis. Mongrel dogs were divided into two groups of 20 animals each. During the preoperative period (24 h) group A was not subjected to MBP, and group B was fasted and ingested 20 ml magnesium hydroxide plus 15 ml/kg 10% mannitol orally. All animals underwent segmental colectomy followed by end-to-end anastomosis. The survivors of both groups were reoperated upon on the 7th postoperative day. Mortality before reoperation was significantly higher in group A (45%) than in group B (10%; P0.05). Aerobic and anaerobic bacterial cultures showed similar growth in the two groups. We conclude that the omission of MBP increased the mortality due to early anastomotic leakage with peritonitis; MBP did not change the rate of localized anastomotic leakage, leakage with peritonitis, or intact anastomoses on the 7th day; no quantitative or qualitative differences were observed in the bacteria isolated from the two groups.

  10. Molecular modeling, FTIR spectral characterization and mechanical properties of carbonated-hydroxyapatite prepared by mechanochemical synthesis

    Energy Technology Data Exchange (ETDEWEB)

    Youness, Rasha A. [Spectroscopy Department, National Research Centre, El-Bohouth Str., 12622, Dokki, Giza (Egypt); Taha, Mohammed A. [Solid-State Physics Department, National Research Centre, El-Bohouth Str., 12622, Dokki, Giza (Egypt); Elhaes, Hanan [Physics Department, Faculty of Women for Arts, Science, and Education, Ain Shams University, 11757 Cairo (Egypt); Ibrahim, Medhat, E-mail: medahmed6@yahoo.com [Spectroscopy Department, National Research Centre, El-Bohouth Str., 12622, Dokki, Giza (Egypt)

    2017-04-01

    Nanocrystalline B-type carbonate substituted hydroxyapatite (B-CHA) powder has been successively synthesized by mechanochemical method. The effect of milling times on the formation of B-CHA was investigated by Fourier transform infrared spectroscopy, X-ray diffraction technique and scanning electron microscopy. Moreover, physical as well as mechanical properties were examined as a function of milling time. Furthermore, theoretical model was presented for hydroxyapatite (HA). Semiempirical calculations at PM6 level were used to calculate thermal parameters including entropy; enthalpy; heat capacity; free energy and heat of formation in the temperature range from 200 up to 500 k. The results revealed that single phase B-CHA was successfully formed after 8 h of milling when Ball to Powder Ratio (BPR) equals to 10:1. Results revealed that entropy; enthalpy and heat capacity gradually increased as a function of temperature while, free energy and heat of formation decreased with the increasing of temperature. Comparison with higher level of theory was conducted at HF and DFT using the models HF/3-21g**; B3LYP/6-31G(d,p) and B3LYP/LANL2DZ, respectively and indicated that PM6 could be utilized with appropriate accuracy and time to study physical and thermochemical parameters for HA. - Highlights: • Preparation of Nanocrystalline B-type carbonate substituted hydroxyapatite (B-CHA) powder by mechanochemical method. • Characterization of CHA. • Semiemperical and DFT models for CHA.

  11. Corporate Politics on Polish Millennials

    OpenAIRE

    Natalia Roślik

    2017-01-01

    In the very beginning of this particular paper, an author is trying to determine and describe who Millennials actually are. Then, the basis of Millennials definition is analysing corporation’s activity over the past years regarding this age group. The main goal of the thesis is to bring their specific futures out and describe what corporations on Polish job market are doing to encourage them to work in their offices. Especially in Poland within the last years, it is observed that big multinat...

  12. Polish Foundation for Energy Efficiency

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1995-12-31

    The Polish Foundation for Energy Efficiency (FEWE) was established in Poland at the end of 1990. FEWE, as an independent and non-profit organization, has the following objectives: to strive towards an energy efficient national economy, and to show the way and methods by use of which energy efficiency can be increased. The activity of the Foundation covers the entire territory of Poland through three regional centers: in Warsaw, Katowice and Cracow. FEWE employs well-known and experienced specialists within thermal and power engineering, civil engineering, economy and applied sciences. The organizer of the Foundation has been Battelle Memorial Institute - Pacific Northwest Laboratories from the USA.

  13. The coercivity mechanism of Pr–Fe–B nanoflakes prepared by surfactant-assisted ball milling

    Energy Technology Data Exchange (ETDEWEB)

    Zuo, Wen-Liang, E-mail: wlzuo@iphy.ac.cn; Zhang, Ming; Niu, E.; Shao, Xiao-Ping; Hu, Feng-Xia; Sun, Ji-Rong; Shen, Bao-Gen, E-mail: shenbg@aphy.iphy.ac.cn

    2015-09-15

    The strong (00l) textured Pr{sub 12+x}Fe{sub 82−x}B{sub 6} (x=0, 1, 2, 3, 4) nanoflakes with high coercivity were prepared by surfactant-assisted ball milling (SABM). The thickness and length of the flakes are mainly in the range of 50−200 nm and 0.5−2 μm, respectively. A coercivity of 4.16 kOe for Pr{sub 15}Fe{sub 79}B{sub 6} nanoflakes was obtained, which is the maximum coercivity of R{sub 2}Fe{sub 14}B (R=Pr, Nd) nanoflakes or nanoparticles reported up to now. The results of XRD and SEM for the aligned Pr{sub 15}Fe{sub 79}B{sub 6} nanoflakes indicate that a strong (00l) texture is obtained and the easy magnetization direction is parallel to the surface of the flakes. The angular dependence of coercivity for aligned sample indicates that the coercivity mechanism of the as-milled nanoflakes is mainly dominated by domain wall pinning. Meanwhile, the field dependence of coercivity, isothermal (IRM) and dc demagnetizing (DCD) remanence curves also indicate that the coercivity is mainly determined by domain wall pinning, and nucleation also has an important effect. In addition, the mainly interaction of flakes is dipolar coupling. The research of coercivity mechanism for Pr{sub 15}Fe{sub 79}B{sub 6} nanoflakes is important for guidance the further increase its value, and is useful for the future development of the high performance nanocomposite magnets and soft/hard exchange spring magnets. - Highlights: • A coercivity of 4.16 kOe for Pr{sub 15}Fe{sub 79}B{sub 6} nanoflakes was obtained. • The strong (00l) textured is obtained for Pr{sub 15}Fe{sub 79}B{sub 6} nanoflakes. • The interaction of nanoflakes is mainly dipolar coupling. • Domain wall pinning is the mainly coercivity mechanism.

  14. Novel cavitation fluid jet polishing process based on negative pressure effects.

    Science.gov (United States)

    Chen, Fengjun; Wang, Hui; Tang, Yu; Yin, Shaohui; Huang, Shuai; Zhang, Guanghua

    2018-04-01

    Traditional abrasive fluid jet polishing (FJP) is limited by its high-pressure equipment, unstable material removal rate, and applicability to ultra-smooth surfaces because of the evident air turbulence, fluid expansion, and a large polishing spot in high-pressure FJP. This paper presents a novel cavitation fluid jet polishing (CFJP) method and process based on FJP technology. It can implement high-efficiency polishing on small-scale surfaces in a low-pressure environment. CFJP uses the purposely designed polishing equipment with a sealed chamber, which can generate a cavitation effect in negative pressure environment. Moreover, the collapse of cavitation bubbles can spray out a high-energy microjet and shock wave to enhance the material removal. Its feasibility is verified through researching the flow behavior and the cavitation results of the negative pressure cavitation machining of pure water in reversing suction flow. The mechanism is analyzed through a computational fluid dynamics simulation. Thus, its cavitation and surface removal mechanisms in the vertical CFJP and inclined CFJP are studied. A series of polishing experiments on different materials and polishing parameters are conducted to validate its polishing performance compared with FJP. The maximum removal depth increases, and surface roughness gradually decreases with increasing negative outlet pressures. The surface becomes smooth with the increase of polishing time. The experimental results confirm that the CFJP process can realize a high material removal rate and smooth surface with low energy consumption in the low-pressure environment, together with compatible surface roughness to FJP. Copyright © 2017 Elsevier B.V. All rights reserved.

  15. Chromatic stability of acrylic resins of artificial eyes submitted to accelerated aging and polishing.

    Science.gov (United States)

    Goiato, Marcelo Coelho; Santos, Daniela Micheline dos; Souza, Josiene Firmino; Moreno, Amália; Pesqueira, Aldiéris Alves

    2010-12-01

    Esthetics and durability of materials used to fabricate artificial eyes has been an important issue since artificial eyes are essential to restore esthetics and function, protect the remaining tissues and help with patients' psychological therapy. However, these materials are submitted to degrading effects of environmental agents on the physical properties of the acrylic resin. This study assessed the color stability of acrylic resins used to fabricate sclera in three basic shades (N1, N2 and N3) when subjected to accelerated aging, mechanical and chemical polishing. Specimens of each resin were fabricated and submitted to mechanical and chemical polishing. Chromatic analysis was performed before and after accelerated aging through ultraviolet reflection spectrophotometry. All specimens revealed color alteration following polishing and accelerated aging. The resins presented statistically significant chromatic alteration (p<0.01) between the periods of 252 and 1008 h. Both polishing methods presented no significant difference between the values of color derivatives of resins.

  16. Comparative evaluation of effect of different polishing systems on surface roughness of composite resin: An in vitro study.

    Science.gov (United States)

    Chour, Rashmi G; Moda, Aman; Arora, Arpana; Arafath, Muhmmed Y; Shetty, Vikram K; Rishal, Yousef

    2016-08-01

    Satisfactory composite restoration depends upon its smooth finish, quality of polishing agents, type of composite material used, and its composition. The present study evaluated the effect of different polishing systems on the surface roughness of composite resin. Forty discs of composite were prepared and equally subjected to different finishing and polishing procedures; (i) unpolished control group, (ii) sof-lex discs, (iii) diamond tips, and (iv) Astrobrush groups. Later, the surface roughness for the entire specimen was evaluated using Profilomotor. Data were tabulated and statistically analyzed using analysis of variance and Tukey's test at significance level of 0.001. Composite surface roughness after polishing was statistically significant between the groups. Sof-lex group produced lesser surface roughness compared to control, Astrobrush, and diamond group. The present study indicated that diamond tips can be used to remove rough surface whereas sof-lex can be used for final finish and polish of the composite restoration.

  17. Effects of various polishing media and techniques on the surface finish and behavior of laser glasses

    International Nuclear Information System (INIS)

    Landingham, R.L.; Casey, A.W.; Lindahl, R.O.

    1978-01-01

    The advance of high-power laser technology is dependent on the rate of advancement in laser glass forming and surface preparation. The threshold damage of glass surfaces continues to be a weak link in the overall advancement of laser technology. Methods were developed and used in the evaluation of existing glass surface preparation techniques. Modified procedures were evaluated to reduce surface contamination and subsurface defects. Polishing rates were monitored under controlled polishing conditions (purity, pH, particle size distribution, particle concentration, etc.). Future work at LLL for this ongoing investigation is described

  18. Pine growth and plant community response to chemical vs. mechanical site preparation for establishing loblolly and slash pine

    Science.gov (United States)

    James H. Miller; Zhijuan Qiu

    1995-01-01

    Chemical and mechanical site preparation methods were studied for establishing loblolly (Pinus taeda L) and slash (P. elliottii var. elliottii Engelm.) pine following both integrated fuelwood-pulpwood harvesting and conventional whole-tree harvesting of pines and hardwoods in southem Alabama's Middle Coastal...

  19. Effect of sintering conditions on the microstructural and mechanical characteristics of porous magnesium materials prepared by powder metallurgy.

    Science.gov (United States)

    Čapek, Jaroslav; Vojtěch, Dalibor

    2014-02-01

    There has recently been an increased demand for porous magnesium materials in many applications, especially in the medical field. Powder metallurgy appears to be a promising approach for the preparation of such materials. Many works have dealt with the preparation of porous magnesium; however, the effect of sintering conditions on material properties has rarely been investigated. In this work, we investigated porous magnesium samples that were prepared by powder metallurgy using ammonium bicarbonate spacer particles. The effects of the purity of the argon atmosphere and sintering time on the microstructure (SEM, EDX and XRD) and mechanical behaviour (universal loading machine and Vickers hardness tester) of porous magnesium were studied. The porosities of the prepared samples ranged from 24 to 29 vol.% depending on the sintering conditions. The purity of atmosphere played a significant role when the sintering time exceeded 6h. Under a gettered argon atmosphere, a prolonged sintering time enhanced diffusion connections between magnesium particles and improved the mechanical properties of the samples, whereas under a technical argon atmosphere, oxidation at the particle surfaces caused deterioration in the mechanical properties of the samples. These results suggest that a refined atmosphere is required to improve the mechanical properties of porous magnesium. © 2013.

  20. Preparation of crosslinked poly (acryloyloxyethyltrimethyl ammonium chloride) microsphere and its adsorption and mechanism towards shikimic acid

    Energy Technology Data Exchange (ETDEWEB)

    Men, Jiying, E-mail: menjiying@nuc.edu.cn; Wang, Ruixin; Li, Huan; Li, Xinyan; Yang, Shanshan; Liu, Haisi; Gao, Baojiao

    2017-02-01

    Shikimic acid (SA) is a key raw material for the synthesis of the antiviral drug, but its extraction and separation from plants is still limited. Crosslinked poly (acryloyloxyethyltrimethyl ammonium chloride, DAC) microspheres were synthesized via inverse-phase suspension polymerization. In the synthesizing, N,N′-methylene bisacrylamide (MBA) was used as crosslinker, cyclohexane as dispersed medium and span-60 as dispersants, obtaining CPDAC gel microspheres. The effect of polymerization condition on balling performance and the characteristics of CPDAC were examined. The adsorption properties of CPDAC towards SA were mainly explored and the data of adsorption isotherm were analyzed by using Langmuir, Freundlich, Temkin, Sips and Toth models. Furthermore, the adsorption mechanism was analyzed in depth, and the adsorption thermodynamics was also investigated. The results show that in order to prepare CPDAC, water phase must be added dropwise to oil phase, and the volume ratio of oil-water is more than 2:1. The mean diameter of CPDAC decreases with increasing span-60 and accelerating agitating rate. The strong electrostatic interaction is formed between quaternary ammonium nitrogen of CPDAC and −COO{sup –} of SA. The adsorption kinetic data is fitted well with pseudo-first-order model. The adsorption ability is higher in aqueous water than ethanol, reaching 108 mg/g, and Toth model is more suitable for describing the actual adsorption process. The adsorption of CPDAC towards SA is dependent on the pH value of the medium. The adsorption process is exothermic, the adsorption amount decreases with the increase of temperature, and the process is driven by enthalpy. The adsorption amount decreases with the increase of salinity. The reusability of CPDAC towards SA can keep 86.1% at the sixth cycle. - Highlights: • CPDAC microspheres were synthesized via inverse-phase suspension polymerization. • SA was adsorbed strongly by strong electrostatic interaction.

  1. Preparation, mechanical, and in vitro properties of glass fiber-reinforced polycarbonate composites for orthodontic application.

    Science.gov (United States)

    Tanimoto, Yasuhiro; Inami, Toshihiro; Yamaguchi, Masaru; Nishiyama, Norihiro; Kasai, Kazutaka

    2015-05-01

    Generally, orthodontic treatment uses metallic wires made from stainless steel, cobalt-chromium-nickel alloy, β-titanium alloy, and nickel-titanium (Ni-Ti) alloy. However, these wires are not esthetically pleasing and may induce allergic or toxic reactions. To correct these issues, in the present study we developed glass-fiber-reinforced plastic (GFRP) orthodontic wires made from polycarbonate and E-glass fiber by using pultrusion. After fabricating these GFRP round wires with a diameter of 0.45 mm (0.018 inch), we examined their mechanical and in vitro properties. To investigate how the glass-fiber diameter affected their physical properties, we prepared GFRP wires of varying diameters (7 and 13 µm). Both the GFRP with 13-µm fibers (GFRP-13) and GFRP with 7 µm fibers (GFRP-7) were more transparent than the metallic orthodontic wires. Flexural strengths of GFRP-13 and GFRP-7 were 690.3 ± 99.2 and 938.1 ± 95.0 MPa, respectively; flexural moduli of GFRP-13 and GFRP-7 were 25.4 ± 4.9 and 34.7 ± 7.7 GPa, respectively. These flexural properties of the GFRP wires were nearly equivalent to those of available Ni-Ti wires. GFRP-7 had better flexural properties than GFRP-13, indicating that the flexural properties of GFRP increase with decreasing fiber diameter. Using thermocycling, we found no significant change in the flexural properties of the GFRPs after 600 or 1,200 cycles. Using a cytotoxicity detection kit, we found that the glass fiber and polycarbonate components comprising the GFRP were not cytotoxic within the limitations of this study. We expect this metal-free GFRP wire composed of polycarbonate and glass fiber to be useful as an esthetically pleasing alternative to current metallic orthodontic wire. © 2014 Wiley Periodicals, Inc.

  2. Compound antimalarial ethosomal cataplasm: preparation, evaluation, and mechanism of penetration enhancement

    Directory of Open Access Journals (Sweden)

    Shen S

    2015-06-01

    Full Text Available Shuo Shen, Shu-Zhi Liu, Yu-Shi Zhang, Mao-Bo Du, Ai-Hua Liang, Li-Hua Song, Zu-Guang Ye Institute of Chinese Materia Medica, China Academy of Chinese Medical Sciences, Beijing, People’s Republic of China Abstract: Malaria is still a serious public health problem in some parts of the world. The problems of recurrence and drug resistance are increasingly more serious. Thus, it is necessary to develop a novel antimalarial agent. The objectives of this study were to construct a novel compound antimalarial transdermal nanosystem–ethosomal cataplasm, to investigate its characteristics and efficiency, and to systematically explore the penetration-enhancing mechanisms of ethosomal cataplasm. Artesunate-loaded ethosomes and febrifugine-loaded ethosomes were prepared, and their characteristics were evaluated. Drug-loaded ethosomes were incorporated in the matrix of cataplasm to form the compound antimalarial ethosomal cataplasm. With the help of ethosomal technology, the accumulated permeation quantity of artesunate significantly increased at 8 hours after administration, which was 1.57 times as much as that of conventional cataplasm. Soon after administration, the ethosomal cataplasm could make a large quantity of antimalarial drug quickly penetrate through skin, then the remaining drug in the ethosomal cataplasm could be steadily released. These characteristics of ethosomal cataplasm are favorable for antimalarial drugs to kill Plasmodium spp. quickly and prevent the resurgence of Plasmodium spp. As expected, the ethosomal cataplasm showed good antimalarial efficiency in this experiment. The negative conversion rates were 100% and the recurrence rates were 0% at all dosages. The mechanism of penetration enhancement of the ethosomal cataplasm was systematically explored using an optics microscope, polarization microscope, and transmission electron microscopy. The microstructure, ultrastructure, and birefringent structure in skin were observed. Data

  3. Polish Industry and Art at CERN

    CERN Multimedia

    2000-01-01

    On 17 October 2000 the second Polish industrial and technological exhibition opened at CERN. The first one was held five years ago and nine of the companies that were present then have come back again this year. Six of those companies were awarded contracts with CERN in 1995. Three Polish officials were present at the Opening Ceremony today: Mrs Malgorzata Kozlowska, Under-secretary of State in the State Committee for Scientific Research, Mr Henryk Ogryczak, Under-secretary of State in Ministry of Economy and Prof. Jerzy Niewodniczanski, President of National Atomic Energy Agency. Professor Luciano Maiani welcomed the Polish delegation to CERN and stressed the important contribution of Polish scientists and industrialists to the work of the laboratory. Director General Luciano Maiani (back left) and head of SPL division Karl-Heinz Kissler (back right) visit the Poland at CERN exhibition… The exhibition offers Polish companies the opportunity to establish professional contacts with CERN. Nineteen companies...

  4. The effect of polishing technique on 3-D surface roughness and gloss of dental restorative resin composites.

    Science.gov (United States)

    Ereifej, N S; Oweis, Y G; Eliades, G

    2013-01-01

    The aim of this study was to compare surface roughness and gloss of resin composites polished using different polishing systems. Five resin composites were investigated: Filtek Silorane (FS), IPS Empress Direct (IP), Clearfil Majesty Posterior (CM), Premise (PM), and Estelite Sigma (ES). Twenty-five disk specimens were prepared from each material, divided into five groups, each polished with one of the following methods: Opti1Step (OS), OptiDisc (OD), Kenda CGI (KD), Pogo (PG), or metallurgical polishing (ML). Gloss and roughness parameters (Sa, Sz, Sq, and St) were evaluated by 60°-angle glossimetry and white-light interferometric profilometry. Two-way analysis of variance was used to detect differences in different materials and polishing techniques. Regression and correlation analyses were performed to examine correlations between roughness and gloss. Significant differences in roughness parameters and gloss were found according to the material, type of polishing, and material/polishing technique (pgloss was recorded for PM/ML (88.4 [2.3]) and lowest for FS/KD (30.3 [5.7]). All roughness parameters were significantly correlated with gloss (r= 0.871, 0.846, 0.713, and 0.707 for Sa, Sq, Sz, St, and gloss, respectively). It was concluded that the polishing procedure and the type of composite can have significant impacts on surface roughness and gloss of resin composites.

  5. Cleaning, abrasion, and polishing effect of novel perlite toothpaste abrasive.

    Science.gov (United States)

    Wang, Bo

    2013-01-01

    This study was intended to optimize perlite particle size and morphology for better tooth cleaning and lower tooth abrasion, and to evaluate the performance of a whitening toothpaste containing the optimized perlite abrasive for tooth cleaning, abrasion, and polishing. Perlite toothpaste abrasive samples were prepared by air classifying a commercial expanded perlite product. The tooth cleaning and abrasion properties for these classified perlite samples were reported via the pellicle cleaning ratio (PCR) and relative dentin abrasion (RDA). Performance of the whitening toothpaste containing the optimized perlite abrasive in tooth cleaning, polishing, and abrasion was evaluated against a widely used synthetic high-cleaning silica. Air classification removes large perlite particles and also physically changes perlite particle morphology from mostly three dimensional and angular particles to mainly two dimensional and platy particles. All the classified samples show good tooth cleaning effect, but tooth abrasion decreases significantly with decreasing particle size. Compared to high-cleaning silica whitening toothpaste, the whitening toothpaste containing the optimized perlite abrasive (PerlClean) is slightly better at tooth cleaning, lower in tooth abrasion, and significantly better at tooth polishing. Fine platy perlite particles are effective in tooth cleaning with low tooth abrasion. The enhanced performance of optimized perlite toothpaste abrasive compared to high-cleaning silica in a whitening toothpaste is attributed to the optimized particle size distribution and the unique platy particle geometry.

  6. Electrochemical Polishing Applications and EIS of a Vitamin B4-Based Ionic Liquid

    International Nuclear Information System (INIS)

    Wixtrom, Alex I.; Buhler, Jessica E.; Reece, Charles E.; Abdel-Fattah, Tarek M.

    2013-01-01

    Modern particle accelerators require minimal interior surface roughness for Niobium superconducting radio frequency (SRF) cavities. Polishing of the Nb is currently achieved via electrochemical polishing with concentrated mixtures of sulfuric and hydrofluoric acids. This acid-based approach is effective at reducing the surface roughness to acceptable levels for SRF use, but due to acid-related hazards and extra costs (including safe disposal of used polishing solutions), an acid-free method would be preferable. This study focuses on an alternative electrochemical polishing method for Nb, using a novel ionic liquid solution containing choline chloride, also known as Vitamin B 4 (VB 4 ). Potentiostatic electrochemical impedance spectroscopy (EIS) was also performed on the VB4-based system. Nb polished using the VB4-based method was found to have a final surface roughness comparable to that achieved via the acid-based method, as assessed by atomic force microscopy (AFM). These findings indicate that acid-free VB 4 -based electrochemical polishing of Nb represents a promising replacement for acid-based methods of SRF cavity preparation

  7. [Comparison of surface roughness of nanofilled and microhybrid composite resins after curing and polishing].

    Science.gov (United States)

    Jiang, Hong; Lv, Da; Liu, Kailei; Zhang, Weisheng; Yao, Yao; Liao, Chuhong

    2014-05-01

    To compare the surface roughness of nanofilled dental composite resin and microhybrid composite resins after curing and polishing. A nanofilled composite (Z350) and 4 microhybrid composites (P60, Z250, Spectrum, and AP-X) were fabricated from the lateral to the medial layers to prepare 8 mm×8 mm×5 mm cubical specimens. The 4 lateral surfaces of each specimens were polished with abrasive disks (Super-Snap). Profilometer was used to test the mean surface roughness (Ra) after polishing. P60 had the lowest Ra (0.125∓0.030 µm) followed by Z250 and Spectrum. The Ra of Z350 (0.205∓0.052 µm) was greater than that of the other 3 resins, and AP-X had the roughest surfaces. Under scanning electron microscope, the polished faces of P60 resin were characterized by minor, evenly distributed particles with fewer scratches; the polished faces of Z350 presented with scratches where defects of the filling material could be seen. The nanofilled composite Z350 has smooth surface after polishing by abrasive disks, but its smoothness remains inferior to that of other micro-hybrid composite resins.

  8. Polish Adaptation of Wrist Evaluation Questionnaires.

    Science.gov (United States)

    Czarnecki, Piotr; Wawrzyniak-Bielęda, Anna; Romanowski, Leszek

    2015-01-01

    Questionnaires evaluating hand and wrist function are a very useful tool allowing for objective and systematic recording of symptoms reported by the patients. Most questionnaires generally accepted in clinical practice are available in English and need to be appropriately adapted in translation and undergo subsequent validation before they can be used in another culture and language. The process of translation of the questionnaires was based on the generally accepted guidelines of the International Quality of Life Assessment Project (IQOLA). First, the questionnaires were translated from English into Polish by two independent translators. Then, a joint version of the translation was prepared collectively and translated back into English. Each stage was followed by a written report. The translated questionnaires were then evaluated by a group of patients. We selected 31 patients with wrist problems and asked them to complete the PRWE, Mayo, Michigan and DASH questionnaires twice at intervals of 3-10 days. The results were submitted for statistical analysis. We found a statistically significant (pquestionnaires. A comparison of the PRWE and Mayo questionnaires with the DASH questionnaire also showed a statistically significant correlation (pquestionnaires was successful and that the questionnaires may be used in clinical practice.

  9. Corporate Politics on Polish Millennials

    Directory of Open Access Journals (Sweden)

    Natalia Roślik

    2017-12-01

    Full Text Available In the very beginning of this particular paper, an author is trying to determine and describe who Millennials actually are. Then, the basis of Millennials definition is analysing corporation’s activity over the past years regarding this age group. The main goal of the thesis is to bring their specific futures out and describe what corporations on Polish job market are doing to encourage them to work in their offices. Especially in Poland within the last years, it is observed that big multinational companies are paying special attention to Millennials and trying to hire them before competitors will do so. As a part of this paper, an author will describe corporate politics and practices on Thomson Reuters and BNY Mellon examples. Within this work, an author is also discussing key features and differences between this generation and Millennials parent’s generation. Additionally, there is a reference to corporate social responsibility concept and work-life balance issues.

  10. Determinants of Polish public debt

    Directory of Open Access Journals (Sweden)

    Tomasz Stryjewski

    2011-12-01

    Full Text Available The crisis, which had its beginning in 2007, turned into the debt crisis of the countries. The examples of Greece, Ireland, Iceland or Spain showed the category of public debt in a new light. Poland, at the turn of 2010/2011 also achieved the upper level of public debt acceptable by the law. In the present situation of the European Union countries being in debt, and even insolvent, the situation in Poland becomes riskier. This article attempts at an empirical verification of the determinants of Polish public debt within 95 months (the data link with the period of time from January 2003 to November 2010. The verification of the main factors which cause the formation of public debt takes place by means of an appropriately verified econometric model.

  11. Mechanical Properties of Warm Mix Asphalt Prepared Using Foamed Asphalt Binders : Executive Summary Report

    Science.gov (United States)

    2011-03-01

    Hot mix asphalt (HMA) is a mixture containing aggregates and asphalt binders prepared at specified : proportions. The aggregates and asphalt binder proportions are determined through a mix design : procedure such as the Marshall Mix Design or the Sup...

  12. Ion-beam mixing of ceramic alloys: preparation and mechanical properties

    International Nuclear Information System (INIS)

    Lewis, M.B.; McHargue, C.J.

    1981-01-01

    Techniques used to produce unique states of pure metals mixed into ceramic materials are presented. The samples were prepared by irradiating a 1-MeV Fe + beam on Al 2 O 3 crystal surfaces over which a thin chromium or zirconium film had been evaporated. The limitations of using noble gas ion beams are noted. Micro Knoop hardness tests performed near the surfaces of the samples indicated a significant increase in the hardness of most samples prepared by ion beam mixing

  13. Forming a health culture of future teachers in Polish educational establishments

    Directory of Open Access Journals (Sweden)

    T.S. IERMAKOVA

    2014-10-01

    Full Text Available Aim: to study the experience of the structure and system of training of future teachers in Polish schools. Material: content analysis of domestic and foreign authors. Used data from the survey of students of Polish universities. Also were used survey results through polish service ANKIETKA. For comparison, a questionnaire survey 35 students of the Faculty of Physical Education (future teachers of physical training and 30 students - the future teachers of elementary school of Ukrainian university. Results: the study of Polish teachers consider health culture of a person as the ability to assess individual and community health needs using in everyday life hygiene and health regulations. There have been some differences among Ukrainian and Polish students in their health and health culture. Among the respondents, Polish students - the future teachers of physical culture, is dominated motives such as the improvement of the physical condition, strengthen self-esteem, as well as improved health. Polish students from other disciplines believe that the most important motive for the adoption of physical activity is a concern for the physical well-being and mental health. The majority of Ukrainian students (future teachers of physical culture believe an important part of building health culture of their direct participation in various sports clubs, as well as the ability to organize physical culture, sports and educational work with students outside the classroom. Ukrainian students (other specialty noted the need to improve health, enhance knowledge in specific subjects humanities and promoting healthy lifestyles. Conclusions: It is recommended to use the experience of preparing students of Polish schools in modern Ukrainian higher education.

  14. Effects of finishing/polishing techniques on microleakage of resin-modified glass ilonomer cement restorations.

    Science.gov (United States)

    Yap, Adrian U J; Yap, W Y; Yeo, Egwin J C; Tan, Jane W S; Ong, Debbie S B

    2003-01-01

    This study investigated the effect of finishing/polishing techniques on the microleakage of resin-modified glass ionomer restorations. Class V preparations were made on the buccal and lingual/palatal surfaces of freshly extracted teeth. The cavities on each tooth were restored with Fuji II LC (FT [GC]) and Photac-Fil Quick (PF [3M-ESPE]) according to manufacturers' instructions. Immediately after light-polymerization, gross finishing was done with eight-fluted tungsten carbide burs. The teeth were then randomly divided into four groups and finishing/polishing was done with one of the following systems: (a) Robot Carbides (RC); (b) Super-Snap system (SS); (c) OneGloss (OG) and (d) CompoSite Polishers (CS). The sample size for each material-finishing/polishing system combination was eight. After finishing/polishing, the teeth were stored in distilled water at 37 degrees C for one week. The root apices were then sealed with acrylic and two coats of varnish was applied 1 mm beyond the restoration margins. The teeth were subsequently subjected to dye penetration testing (0.5% basic fuchsin), sectioned and scored. Data was analyzed using Kruskal-Wallis and Mann-Whitney U tests at a significance level of 0.05. Results of statistical analysis were as follows: Enamel margins: PF-OGpolishing technique, leakage at dentin margins was significantly greater than at enamel margins for FT. For PF, no significant difference in leakage scores was observed between dentin and enamel with the exception of finishing/polishing with OG. FT restorations had significantly less enamel and dentin leakage than PF restorations when treated with OG. The effect of finishing/polishing techniques on microleakage was both tissue and material dependent.

  15. Cleansing orthodontic brackets with air-powder polishing: effects on frictional force and degree of debris.

    Science.gov (United States)

    Leite, Brisa Dos Santos; Fagundes, Nathalia Carolina Fernandes; Aragón, Mônica Lídia Castro; Dias, Carmen Gilda Barroso Tavares; Normando, David

    2016-01-01

    Debris buildup on the bracket-wire interface can influence friction. Cleansing brackets with air-powder polishing can affect this process. The aim of this study was to evaluate the frictional force and amount of debris remaining on orthodontic brackets subjected to prophylaxis with air-powder polishing. Frictional force and debris buildup on the surface of 28 premolar brackets were evaluated after orthodontic treatment. In one hemiarch, each bracket was subjected to air-powder polishing (n = 14) for five seconds, while the contralateral hemiarch (n = 14) served as control. Mechanical friction tests were performed and images of the polished bracket surfaces and control surfaces were examined. Wilcoxon test was applied for comparative analysis between hemiarches at p Brackets that had been cleaned with air-powder polishing showed lower friction (median = 1.27 N) when compared to the control surfaces (median = 4.52 N) (p orthodontic brackets with air-powder polishing significantly reduces debris buildup on the bracket surface while decreasing friction levels observed during sliding mechanics.

  16. Convergent Polishing: A Simple, Rapid, Full Aperture Polishing Process of High Quality Optical Flats & Spheres

    Science.gov (United States)

    Suratwala, Tayyab; Steele, Rusty; Feit, Michael; Dylla-Spears, Rebecca; Desjardin, Richard; Mason, Dan; Wong, Lana; Geraghty, Paul; Miller, Phil; Shen, Nan

    2014-01-01

    Convergent Polishing is a novel polishing system and method for finishing flat and spherical glass optics in which a workpiece, independent of its initial shape (i.e., surface figure), will converge to final surface figure with excellent surface quality under a fixed, unchanging set of polishing parameters in a single polishing iteration. In contrast, conventional full aperture polishing methods require multiple, often long, iterative cycles involving polishing, metrology and process changes to achieve the desired surface figure. The Convergent Polishing process is based on the concept of workpiece-lap height mismatch resulting in pressure differential that decreases with removal and results in the workpiece converging to the shape of the lap. The successful implementation of the Convergent Polishing process is a result of the combination of a number of technologies to remove all sources of non-uniform spatial material removal (except for workpiece-lap mismatch) for surface figure convergence and to reduce the number of rogue particles in the system for low scratch densities and low roughness. The Convergent Polishing process has been demonstrated for the fabrication of both flats and spheres of various shapes, sizes, and aspect ratios on various glass materials. The practical impact is that high quality optical components can be fabricated more rapidly, more repeatedly, with less metrology, and with less labor, resulting in lower unit costs. In this study, the Convergent Polishing protocol is specifically described for fabricating 26.5 cm square fused silica flats from a fine ground surface to a polished ~λ/2 surface figure after polishing 4 hr per surface on a 81 cm diameter polisher. PMID:25489745

  17. Mechanical properties of multi-walled carbon nanotube (MWCNT)/polymethyl methacrylite (PMMA) nanocomposite prepared via the coagulation method

    Science.gov (United States)

    Ismail, Noor Mazni; Aziz, Azizan; Jaafar, Mariatti

    2012-06-01

    Multi-walled carbon nanotube (MWCNT) is well known as one of the best candidates for reinforcing the next generation of high performance nanocomposites due to its excellent mechanical properties. In this study, MWCNTs were dispersed in polymethyl methacrylite (PMMA) matrix to enhance its mechanical strength. MWCNT/PMMA were prepared by simple coagulation method and then hot-pressed to create nanocomposite film consists of rich nanotubes. Samples were prepared in respect to various high filler loading (1%, 3%, 5%, 7% and 10% wt.). Standard ASTM D790 flexural test was used to evaluate the mechanical properties of the composites. The morphology and surface fracture were observed via scanning electron microscope. The properties of the composites where found to be better than the neat PMMA. Flexural strength & flexural modulus of MWCNT/PMMA nanocomposite showed an improvement up to 24.1% and 107.7% compared to the neat PMMA, respectively. These studies therefore demonstrate that MWCNT/PMMA prepared by coagulation method able to successfully improve mechanical properties of PMMA.

  18. Grinding and polishing instead of sectioning for the tissue samples with a graft: Implications for light and electron microscopy.

    Science.gov (United States)

    Mukhamadiyarov, Rinat A; Sevostyanova, Victoria V; Shishkova, Daria K; Nokhrin, Andrey V; Sidorova, Olga D; Kutikhin, Anton G

    2016-06-01

    A broad use of the graft replacement requires a detailed investigation of the host-graft interaction, including both histological examination and electron microscopy. A high quality sectioning of the host tissue with a graft seems to be complicated; in addition, it is difficult to examine the same tissue area by both of the mentioned microscopy techniques. To solve these problems, we developed a new technique of epoxy resin embedding with the further grinding, polishing, and staining. Graft-containing tissues prepared by grinding and polishing preserved their structure; however, sectioning frequently required the explantation of the graft and led to tissue disintegration. Moreover, stained samples prepared by grinding and polishing may then be assessed by both light microscopy and backscattered scanning electron microscopy. Therefore, grinding and polishing outperform sectioning when applied to the tissues with a graft. Copyright © 2016 Elsevier Ltd. All rights reserved.

  19. An investigation on the compressibility of aluminum/nano-alumina composite powder prepared by blending and mechanical milling

    International Nuclear Information System (INIS)

    Razavi Hesabi, Z.; Hafizpour, H.R.; Simchi, A.

    2007-01-01

    The densification response of aluminum powder reinforced with 5 vol.% nanometric alumina particles (35 nm) during uniaxial compaction in a rigid die was studied. The composite powder was prepared by blending and mechanical milling procedures. To determine the effect of the reinforcement nanoparticles on the compressibility of aluminum powder, monolithic Al powder, i.e. without the addition of alumina, was also examined. It was shown that at the early stage of compaction when the rearrangement of particles is the dominant mechanism of the densification, disintegration of the nanoparticle clusters and agglomerates under the applied load contributes in the densification of the composite powder prepared by blending method. As the compaction pressure increases, however, the load partitioning effect of the nanoparticles decreases the densification rate of the powder mixture, resulting in a lower density compared to the monolithic aluminum. It was also shown that mechanical milling significantly impacts the compressibility of the unreinforced and reinforced aluminum powders. Morphological changes of the particles upon milling increase the contribution of particle rearrangement in densification whilst the plastic deformation mechanism is significantly retarded due to the work-hardening effect of the milling process. Meanwhile, the distribution of alumina nanoparticles is improved by mechanical milling, which in fact, affects the compressibility of the composite powder. This paper addresses the effect of mechanical milling and reinforcement nanoparticles on the compressibility of aluminum powder

  20. Challenges of sample preparation for cross sectional EBSD analysis of electrodeposited nickel films

    DEFF Research Database (Denmark)

    Alimadadi, Hossein; Pantleon, Karen

    2009-01-01

    Thorough microstructure and crystallographic orientation analysis of thin films by means of electron backscatter diffraction requires cross section preparation of the film-substrate compound. During careful preparation, changes of the rather non-stable as-deposited microstructure must be avoided....... Different procedures for sample preparation including mechanical grinding and polishing, electropolishing and focused ion beam milling have been applied to a nickel film electrodeposited on top of an amorphous Ni-P layer on a Cu-substrate. Reliable EBSD analysis of the whole cross section can be obtained...

  1. Technological Advances of Robot Assisted Polishing

    DEFF Research Database (Denmark)

    Lazarev, Ruslan; Top, Søren; Grønbæk, Jens

    The efficient polishing of surfaces is very important in mould and die industry. Fine abrasive processes are widely used in industry for the first steps for the production of tools of high quality in terms of finishing accuracy, form and surface integrity. While manufacturing of most components....... In this study, the influence of polishing parameters and type of polishing media on fine abrasive surface finishing is investigated. Experimental study is covering 2D rotational surfaces that is widespread used in mould and dies industry. Application of it is essential for process intelligent control, condition...... monitoring and quality inspection....

  2. Interstitial positions of tin ions in alpha-(FerichSn)(2)O-3 solid solutions prepared by mechanical alloying

    DEFF Research Database (Denmark)

    Jiang, Jianzhong; Lin, Rong; Nielsen, Kurt

    1997-01-01

    The microstructure of samples of 91, 85, and 71 mol % alpha-Fe-2-O-3-SnO2. prepared by mechanical alloying, has been studied by x-ray diffraction with Rietveld structure refinements, On the basis of the structure refinements to the whole x-ray diffraction patterns for the four as-milled samples, ......, it is found that tin ions do not substitute iron ions in the solid solution, although this model is generally assumed in the literature. The Sn4+ ions occupy the empty octahedral holes in the lattice of the alpha-Fe2O3 phase.......The microstructure of samples of 91, 85, and 71 mol % alpha-Fe-2-O-3-SnO2. prepared by mechanical alloying, has been studied by x-ray diffraction with Rietveld structure refinements, On the basis of the structure refinements to the whole x-ray diffraction patterns for the four as-milled samples...

  3. Mechanical properties of 9Cr–1W reduced activation ferritic martensitic steel weldment prepared by electron beam welding process

    Energy Technology Data Exchange (ETDEWEB)

    Das, C.R., E-mail: chitta@igcar.gov.in [Indira Gandhi Center for Atomic Research, Kalpakkam 603102 (India); Albert, S.K. [Indira Gandhi Center for Atomic Research, Kalpakkam 603102 (India); Sam, Shiju [Institute for Plasma Research, Gandhinagar (India); Mastanaiah, P. [Defense Research and Development Laboratory, Hyderabad (India); Chaitanya, G.M.S.K.; Bhaduri, A.K.; Jayakumar, T. [Indira Gandhi Center for Atomic Research, Kalpakkam 603102 (India); Murthy, C.V.S. [Defense Research and Development Laboratory, Hyderabad (India); Kumar, E. Rajendra [Institute for Plasma Research, Gandhinagar (India)

    2014-11-15

    Highlights: • Width of HAZ is smaller in the 9Cr–1W RAFM weldment prepared by EB process compared to that reported for TIG weldments in literature. • Weld joint is stronger than that of the base metal. • Toughness of weld metal prepared by EB welding process is comparable to that (in PWHT condition) prepared by TIG process. • DBTT of as-welded 9Cr–1W RAFM weldment prepared by EB process is comparable to that reported for TIG weld metal in PWHT condition. - Abstract: Microstructure and mechanical properties of the weldments prepared from 9Cr–1W reduced activation ferritic martensitic (RAFM) steel using electron beam welding (EBW) process were studied. Microstructure consists of tempered lath martensite where precipitates decorating the boundaries in post weld heat treated (PWHT) condition. Lath and precipitate sizes were found to be finer in the weld metal than in base metal. Accordingly, hardness of the weld metal was found to be higher than the base metal. Tensile strength of the cross weldment specimen was 684 MPa, which was comparable with the base metal tensile strength of 670 MPa. On the other hand, DBTT of 9Cr–1W weld metal in as-welded condition is similar to that reported for TIG weld metal in PWHT condition.

  4. Mechanical properties of 9Cr–1W reduced activation ferritic martensitic steel weldment prepared by electron beam welding process

    International Nuclear Information System (INIS)

    Das, C.R.; Albert, S.K.; Sam, Shiju; Mastanaiah, P.; Chaitanya, G.M.S.K.; Bhaduri, A.K.; Jayakumar, T.; Murthy, C.V.S.; Kumar, E. Rajendra

    2014-01-01

    Highlights: • Width of HAZ is smaller in the 9Cr–1W RAFM weldment prepared by EB process compared to that reported for TIG weldments in literature. • Weld joint is stronger than that of the base metal. • Toughness of weld metal prepared by EB welding process is comparable to that (in PWHT condition) prepared by TIG process. • DBTT of as-welded 9Cr–1W RAFM weldment prepared by EB process is comparable to that reported for TIG weld metal in PWHT condition. - Abstract: Microstructure and mechanical properties of the weldments prepared from 9Cr–1W reduced activation ferritic martensitic (RAFM) steel using electron beam welding (EBW) process were studied. Microstructure consists of tempered lath martensite where precipitates decorating the boundaries in post weld heat treated (PWHT) condition. Lath and precipitate sizes were found to be finer in the weld metal than in base metal. Accordingly, hardness of the weld metal was found to be higher than the base metal. Tensile strength of the cross weldment specimen was 684 MPa, which was comparable with the base metal tensile strength of 670 MPa. On the other hand, DBTT of 9Cr–1W weld metal in as-welded condition is similar to that reported for TIG weld metal in PWHT condition

  5. Powder-metallurgy preparation of NiTi shape-memory alloy using mechanical alloying and spark-plasma sintering.

    Czech Academy of Sciences Publication Activity Database

    Novák, P.; Moravec, H.; Vojtěch, V.; Knaislová, A.; Školáková, A.; Kubatík, Tomáš František; Kopeček, Jaromír

    2017-01-01

    Roč. 51, č. 1 (2017), s. 141-144 ISSN 1580-2949 R&D Projects: GA ČR(CZ) GA14-03044S Institutional support: RVO:61389021 ; RVO:68378271 Keywords : mechanical alloying * spark plasma sintering * NiTi * shape memory alloy Subject RIV: JG - Metallurgy; JG - Metallurgy (FZU-D) OBOR OECD: Materials engineering ; Materials engineering (FZU-D) Impact factor: 0.436, year: 2016 https://www.researchgate.net/publication/313900224_Powder-metallurgy_preparation_of_NiTi_shape-memory_alloy_using_mechanical_alloying_and_spark-plasma_sintering

  6. Advanced ion exchange resins for PWR condensate polishing

    International Nuclear Information System (INIS)

    Hoffman, B.; Tsuzuki, S.

    2002-01-01

    The severe chemical and mechanical requirements of a pressurized water reactor (PWR) condensate polishing plant (CPP) present a major challenge to the design of ion exchange resins. This paper describes the development and initial operating experience of improved cation and anion exchange resins that were specifically designed to meet PWR CPP needs. Although this paper focuses specifically on the ion exchange resins and their role in plant performance, it is also recognized and acknowledged that excellent mechanical design and operation of the CPP system are equally essential to obtaining good results. (authors)

  7. Microstructural and mechanical properties of Al-Mg/Al{sub 2}O{sub 3} nanocomposite prepared by mechanical alloying

    Energy Technology Data Exchange (ETDEWEB)

    Safari, J., E-mail: safari.jam@gmail.com [Department of Material Science and Engineering, Shahid Bahonar University of Kerman, P.O. Box No. 76135-133, Kerman (Iran, Islamic Republic of); Akbari, G.H. [Department of Material Science and Engineering, Shahid Bahonar University of Kerman, P.O. Box No. 76135-133, Kerman (Iran, Islamic Republic of); Research Center for Mineral Industries, Shahid Bahonar University of Kerman, P.O. Box No. 76135-133, Kerman (Iran, Islamic Republic of); Shahbazkhan, A. [Islamic Azad University, Saveh Branch, Saveh (Iran, Islamic Republic of); Delshad Chermahini, M. [Materials and Energy Research Center, Karaj (Iran, Islamic Republic of)

    2011-09-29

    Highlights: > The presence of Mg has remarkable effects on crystallite size and lattice strain. > The solution of Mg in the Al matrix accelerates the mechanical milling stages. > The microhardness increased in the presence of Mg. > The presence of Mg has significant effect on lattice parameter. > Steady-state situation was occurred in presence of Mg. - Abstract: The effect of milling time on the microstructure and mechanical properties of Al and Al-10 wt.% Mg matrix nanocomposites reinforced with 5 wt.% Al{sub 2}O{sub 3} during mechanical alloying was investigated. Steady-state situation was occurred in Al-10Mg/5Al{sub 2}O{sub 3} nanocomposite after 20 h, due to solution of Mg into Al matrix, while the situation was not observed in Al/5Al{sub 2}O{sub 3} nanocomposite at the same time. For the binary Al-Mg matrix, after 10 h, the predominant phase was an Al-Mg solid solution with an average crystallite size 34 nm. Up to 10 h, the lattice strain increased to about 0.4 and 0.66% for Al and Al-Mg matrix, respectively. The increasing of lattice parameter due to dissolution of Mg atom into Al lattice during milling was significant. By milling for 10 h the dramatic increase in microhardness (155 HV) for Al-Mg matrix nanocomposite was caused by grain refinement and solid solution formation. From 10 to 20 h, slower rate of increasing in microhardness may be attributed to the completion of alloying process, and dynamic and static recovery of powders.

  8. Jewish problem in the Polish Communist Party

    Directory of Open Access Journals (Sweden)

    Cimek Henryk

    2016-12-01

    Full Text Available Jews accounted for approx. 8-10% of the population of the Second Republic and in the communist movement (Polish Communist Party and Polish Communist Youth Union the rate was approx, 30%, while in subsequent years it much fluctuated. The percentage of Jews was the highest in the authorities of the party and in the KZMP. This had a negative impact on the position of the KPP on many issues, especially in its relation to the Second Republic.

  9. Trace element analysis of nail polishes

    International Nuclear Information System (INIS)

    Misra, G.; Mittal, V.K.; Sahota, H.S.

    1999-01-01

    Instrumental neutron activation analysis (INAA) technique was used to measure the concentrations of various trace elements in nail polishes of popular Indian and foreign brands. The aim of the present experiment was to see whether trace elements could distinguish nail polishes of different Indian and foreign brands from forensic point of view. It was found that cesium can act as a marker to differentiate foreign and Indian brands. (author)

  10. Surface morphology changes of acrylic resins during finishing and polishing phases

    Directory of Open Access Journals (Sweden)

    Glaucio Serra

    2013-12-01

    Full Text Available INTRODUCTION: The finishing and polishing phases are essential to improve smoothness and shining on the surface of acrylic resins used to make removable orthodontic appliances. A good surface finishing reduces roughness, which facilitates hygiene, prevents staining and provides greater comfort to the patients. OBJECTIVE: The aim of this paper was to analyze the changes on surface morphology of acrylic resins during finishing and polishing phases. METHODS: Thirty discs (10 mm in diameter and 5 mm in length were made with acrylic resin and randomly divided into ten groups. The control group did not receive any treatment while the other groups received gradual finishing and polishing. The last group received the entire finishing and polishing procedures. Surface morphology was qualitatively analyzed through scanning electron microscopy and quantitatively analyzed through a laser profilometer test. RESULTS: The acrylic resin surfaces without treatment showed bubbles which were not observed in the subsequent phases. Wearing out with multilaminated burs, finishing with wood sandpaper and finishing with water sandpaper resulted in surfaces with decreasing irregularities. The surfaces that were polished with pumice and with low abrasive liquids showed high superficial smoothness. CONCLUSION: Highly smooth acrylic resin surfaces can be obtained after mechanical finishing and polishing performed with multilaminated burs, wood sandpaper, water sandpaper, pumice and low abrasive liquids.

  11. Experimental Polish-Lithuanian Corpus with the Semantic Annotation Elements

    Directory of Open Access Journals (Sweden)

    Danuta Roszko

    2015-06-01

    Full Text Available Experimental Polish-Lithuanian Corpus with the Semantic Annotation Elements In the article the authors present the experimental Polish-Lithuanian corpus (ECorpPL-LT formed for the idea of Polish-Lithuanian theoretical contrastive studies, a Polish-Lithuanian electronic dictionary, and as help for a sworn translator. The semantic annotation being brought into ECorpPL-LT is extremely useful in Polish-Lithuanian contrastive studies, and also proves helpful in translation work.

  12. Laser polishing of additive manufactured Ti alloys

    Science.gov (United States)

    Ma, C. P.; Guan, Y. C.; Zhou, W.

    2017-06-01

    Laser-based additive manufacturing has attracted much attention as a promising 3D printing method for metallic components in recent years. However, surface roughness of additive manufactured components has been considered as a challenge to achieve high performance. In this work, we demonstrate the capability of fiber laser in polishing rough surface of additive manufactured Ti-based alloys as Ti-6Al-4V and TC11. Both as-received surface and laser-polished surfaces as well as cross-section subsurfaces were analyzed carefully by White-Light Interference, Confocal Microscope, Focus Ion Beam, Scanning Electron Microscopy, Energy Dispersive Spectrometer, and X-ray Diffraction. Results revealed that as-received Ti-based alloys with surface roughness more than 5 μm could be reduce to less than 1 μm through laser polishing process. Moreover, microstructure, microhardness and wear resistance of laser-polished zone was investigated in order to examine the thermal effect of laser polishing processing on the substrate of additive manufactured Ti alloys. This proof-of-concept process has the potential to effectively improve the surface roughness of additive manufactured metallic alloy by local polishing method without damage to the substrate.

  13. Conformal polishing approach: Tool footprint analysis

    Directory of Open Access Journals (Sweden)

    José A Dieste

    2016-02-01

    Full Text Available Polishing process is one of the most critical manufacturing processes during a metal part production because it determines the final quality of the product. Free-form surface polishing is a handmade process with lots of rejected parts, scrap generation and time and energy consumption. Two different research lines are being developed: prediction models of the final surface quality parameters and an analysis of the amount of material removed depending on the polishing parameters to predict the tool footprint during the polishing task. This research lays the foundations for a future automatic conformal polishing system. It is based on rotational and translational tool with dry abrasive in the front mounted at the end of a robot. A tool to part concept is used, useful for large or heavy workpieces. Results are applied on different curved parts typically used in tooling industry, aeronautics or automotive. A mathematical model has been developed to predict the amount of material removed in function of polishing parameters. Model has been fitted for different abrasives and raw materials. Results have shown deviations under 20% that implies a reliable and controllable process. Smaller amount of material can be removed in controlled areas of a three-dimensional workpiece.

  14. Interculutral Polish-Chinese QQing

    Directory of Open Access Journals (Sweden)

    Elżbieta Gajek

    2012-12-01

    Full Text Available Working in tandem with the use of information and communication technologies is well-known and frequently used as a method of supporting learning of foreign languages in authentic communication. It is based on a constructivist approach to teaching. In the reported case study Polish and Chinese students discussed in English preprepared topics. The work shows the potential of e-learning at the micro level, as the language and intercultural task is implemented into an academic course without modification of the objectives and learning outcomes of the course. Evaluation carried out at the end of the project indicates that both groups perceived the task as a significant linguistic, cultural and personal experience. They stressed the importance of sharing “culture for culture” as the partner culture was new for most of them. The ability to talk and respond to information which was often strange, from the point of view of their own culture, allowed for learning intercultural competence ̔in action’.

  15. Effects of surface polishing and annealing on the optical conductivity of intermetallic compounds

    CERN Document Server

    Rhee, J Y

    1999-01-01

    The optical conductivity spectra of several intermetallic compounds were measured by spectroscopic ellipsometry. Three spectra were measured for each compound; just after the sample was mechanically polished, at high temperature, and after the sample was annealed at 110 .deg. C for at least one day and cooled to room temperature. An equiatomic FeTi alloy showed the typical effects of annealing after mechanical polishing of surface. The spectrum after annealing had a larger magnitude and sharper structures than the spectrum before annealing. We also observed shifts of peaks in the spectrum. A relatively low-temperature annealing gave rise to unexpectedly substantial effects, and the effects were explained by recrystallization and/or a disorder -> order transition of the surface of the sample which was damaged and, hence, became highly disordered by mechanical polishing. Similar effects were also observed when the sample temperature was lowered. The observed changes upon annealing could partly be explained by p...

  16. The Effect of Grinding and Polishing Procedure of Tool Steels in Sheet Metal Forming

    DEFF Research Database (Denmark)

    Lindvall, F.; Bergström, J.; Krakhmalev, P.

    2010-01-01

    The surface finish of tools in sheet metal forming has a large influence on the performance of the forming tool. Galling, concern of wear in sheet metal forming, is a severe form of adhesive wear where sheet material is transferred on to the tool surface. By polishing the tools to a fine surface ...... 40 and Vanadis 6 and up to ten different grinding and polishing treatments were tested against AISI 316 stainless steel. The tests showed that an optimum surface preparation might be found at the transition between abrasive and adhesive wear....

  17. Flaw preparations for HSST program vessel fracture mechanics testing: mechanical-cyclic pumping and electron-beam weld-hydrogen-charge cracking schemes

    International Nuclear Information System (INIS)

    Holz, P.P.

    1980-06-01

    The purpose of the document is to present schemes for flaw preparations in heavy section steel. The ability of investigators to grow representative sharp cracks of known size, location, and orientation is basic to representative field testing to determine data for potential flaw propagation, fracture behavior, and margin against fracture for high-pressure-, high-temperature-service steel vessels subjected to increasing pressurization and/or thermal shock. Gaging for analytical stress and strain procedures and ultrasonic and acoustic emission instrumentation can then be applied to monitor the vessel during testing and to study crack growth. This report presents flaw preparations for HSST fracture mechanics testing. Cracks were grown by two techniques: (1) a mechanical method wherein a premachined notch was sharpened by pressurization and (2) a method combining electron-beam welds and hydrogen charging to crack the chill zone of a rapidly placed autogenous weld. The mechanical method produces a naturally occurring growth shape controlled primarily by the shape of the machined notch; the welding-electrochemical method produces flaws of uniform depth from the surface of a wall or machined notch. Theories, details, discussions, and procedures are covered for both of the flaw-growing schemes

  18. [Fifty years of the Polish School of Medicine at the University of Edinburgh (1941-1991)].

    Science.gov (United States)

    Tomaszewski, W

    1994-01-01

    which was celebrated by the University, influenced the participants to organise regular quinquennial world reunions in Edinburgh. A later, particularly memorable event, was the world reunion in 1976 on the occasion of the 250th anniversary of the Medical Faculty of the University; it was celebrated jointly, as it coincided with the 35th anniversary of the Polish School. The 45th anniversary of the School in 1986 was marked by the opening of the "Polish School of Medicine Historical Collection" in the Polish Room of the Erskine Medical Library of the University of Edinburgh. Also a Polish School of Medicine Memorial Fund, founded on contributions from the graduates, was inaugurated at the University of Edinburgh to provide scholarships for research workers from Poland. Another venture was the "Professor Antoni Jurasz Lectureship" for professors of the Edinburgh Medical Faculty to promote contact with Medical Schools in Poland by delivering lectures. An ardent desire was expressed by the original organisers of the School to continue into the future the academic links in medicine between the University and Poland. Political and ideological factors which devided the post-war Europe did not favor such a fulfillment of this plan. The members of the School who remained in the West, maintained links with the University and prepared funds to put the plans of co-operation into action. With the end of the political division of Europe the future of a productive Scottish-Polish collaboration can be viewed with hope and confidence.

  19. Preparation and mechanical properties of ultra-high-strength nanocrystalline metals

    Czech Academy of Sciences Publication Activity Database

    Marek, I.; Vojtěch, D.; Michalcová, A.; Kubatík, Tomáš František

    2015-01-01

    Roč. 15, č. 4 (2015), s. 596-600 ISSN 1213-2489 Institutional support: RVO:61389021 Keywords : Mechanical properties * Nanocrystalline materials * Selective leaching * Silver * Spark plasma sintering Subject RIV: JG - Metallurgy

  20. 1.06 μm 150 psec laser damage study of diamond turned, diamond turned/polished and polished metal mirrors

    International Nuclear Information System (INIS)

    Saito, T.T.; Milam, D.; Baker, P.; Murphy, G.

    1975-01-01

    Using a well characterized 1.06 μm 150 ps glass laser pulse the damage characteristics for diamond turned, diamond turned/ polished, and polished copper and silver mirrors less than 5 cm diameter were studied. Although most samples were tested with a normal angle of incidence, some were tested at 45 0 with different linear polarization showing an increase in damage threshold for S polarization. Different damage mechanisms observed will be discussed. Laser damage is related to residual surface influences of the fabrication process. First attempts to polish diamond turned surfaces resulted in a significant decrease in laser damage threshold. The importance of including the heat of fusion in the one dimensional heat analysis of the theoretical damage threshold and how close the samples came to the theoretical damage threshold is discussed. (auth)

  1. Solvothermal tuning of photoluminescent graphene quantum dots: from preparation to photoluminescence mechanism

    Science.gov (United States)

    Qi, Bao-Ping; Zhang, Xiaoru; Shang, Bing-Bing; Xiang, Dongshan; Zhang, Shenghui

    2018-02-01

    Solvothermal synthesis was employed to tune the surface states of graphene quantum dots (GQDs). Two series of GQDs with the particle sizes from 2.6 to 4.5 nm were prepared as follows: (I) GQDs with the same size but different oxygen degrees; (II) GQDs with different core sizes but the similar surface chemistry. Both the large sizes and the high surface oxidation degrees led to the redshift photoluminescence (PL) of GQDs. Electrochemiluminescence (ECL) spectra from two series of GQDs were all in accordance with their PL spectra, respectively, which provided good evidence for the conjugated structures in GQDs responsible for PL. [Figure not available: see fulltext.

  2. Influence of preparation technique of ceramic superconductors on structure, mechanical and electrical properties

    International Nuclear Information System (INIS)

    Tomandl, G.; Kohl, R.

    1991-01-01

    Sol-Gel-like preparation techniques using citrate-, citrate/ethylenglycol- as well as ethylhexanoate precursors and the addition of fluorine were tested with regard to homogeneity and properties of HTSC-ceramics. A few single- and polycrystalline materials were coated with YBaCuOxide- and Bi Sr Ca Cu Oxide-films using ethylhexanoate-precursors. Interdiffusion reactions were investigated affecting the electrical properties. The best results in YBaCuOxide system were obtained using polycrystalline magnesia and silver as substrate materials. Bulk ceramics with a high degree of orientation were fabricated by reaction sintering and simultaneous external pressure. (orig.) With 44 refs., 6 tabs., 81 figs [de

  3. Superconductive properties, interaction mechanisms, materials preparation and electronic transport in high-Tc superconductors

    International Nuclear Information System (INIS)

    Saemann-Ischenko, G.

    1993-01-01

    The final report is composed of eight chapters dealing with the following aspects: I. Mixed state, critical currents, anisotropy, intrinsic and extrinsic pinning. II. Microwave properties and far-infrared reflectivity of epitactic HTSC films. III. Hall effect at the states of normal conductivity and superconductivity, magnetoresistance, superconducting fluctuation phenomena. IV. Effects of the nuclear and the electronic energy loss. V. Scanning electron microscopy. VI. p- and n-doped high-Tc superconductors: Charge symmetry and magnetism. VII. Preparation methods. VIII. Electrochemical examinations of HTSC films and HTSC monocrystals at low temperatures. (orig./MM) [de

  4. Comparison of the Nanostructure and Mechanical Performance of Highly Exfoliated Epoxy-Clay Nanocomposites Prepared by Three Different Protocols.

    Science.gov (United States)

    Shiravand, Fatemeh; Hutchinson, John M; Calventus, Yolanda; Ferrando, Francesc

    2014-05-30

    Three different protocols for the preparation of polymer layered silicate nanocomposites based upon a tri-functional epoxy resin, triglycidyl para -amino phenol (TGAP), have been compared in respect of the cure kinetics, the nanostructure and their mechanical properties. The three preparation procedures involve 2 wt% and 5 wt% of organically modified montmorillonite (MMT), and are: isothermal cure at selected temperatures; pre-conditioning of the resin-clay mixture before isothermal cure; incorporation of an initiator of cationic homopolymerisation, a boron tri-fluoride methyl amine complex, BF₃·MEA, within the clay galleries. It was found that features of the cure kinetics and of the nanostructure correlate with the measured impact strength of the cured nanocomposites, which increases as the degree of exfoliation of the MMT is improved. The best protocol for toughening the TGAP/MMT nanocomposites is by the incorporation of 1 wt% BF₃·MEA into the clay galleries of nanocomposites containing 2 wt% MMT.

  5. Smoking characteristics of Polish immigrants in Dublin.

    LENUS (Irish Health Repository)

    Kabir, Zubair

    2008-01-01

    BACKGROUND: This study examined two main hypotheses: a) Polish immigrants\\' smoking estimates are greater than their Irish counterparts (b) Polish immigrants purchasing cigarettes from Poland smoke "heavier" (>\\/= 20 cigarettes a day) when compared to those purchasing cigarettes from Ireland. The study also set out to identify significant predictors of \\'current\\' smoking (some days and everyday) among the Polish immigrants. METHODS: Dublin residents of Polish origin (n = 1,545) completed a previously validated Polish questionnaire in response to an advertisement in a local Polish lifestyle magazine over 5 weekends (July-August, 2007). The Office of Tobacco Control telephone-based monthly survey data were analyzed for the Irish population in Dublin for the same period (n = 484). RESULTS: Age-sex adjusted smoking estimates were: 47.6% (95% Confidence Interval [CI]: 47.3%; 48.0%) among the Poles and 27.8% (95% CI: 27.2%; 28.4%) among the general Irish population (p < 0.001). Of the 57% of smokers (n = 345\\/606) who purchased cigarettes solely from Poland and the 33% (n = 198\\/606) who purchased only from Ireland, 42.6% (n = 147\\/345) and 41.4% (n = 82\\/198) were "heavy" smokers, respectively (p = 0.79). Employment (Odds Ratio [OR]: 2.89; 95% CI: 1.25-6.69), lower education (OR: 3.76; 95%CI: 2.46-5.74), and a longer stay in Ireland (>24 months) were significant predictors of current smoking among the Poles. An objective validation of the self-reported smoking history of a randomly selected sub-sample immigrant group, using expired carbon monoxide (CO) measurements, showed a highly significant correlation coefficient (r = 0.64) of expired CO levels with the reported number of cigarettes consumed (p < 0.0001). CONCLUSION: Polish immigrants\\' smoking estimates are higher than their Irish counterparts, and particularly if employed, with only primary-level education, and are overseas >2 years.

  6. Standard guide for preparation of metallographic specimens

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2011-01-01

    1.1 The primary objective of metallographic examinations is to reveal the constituents and structure of metals and their alloys by means of a light optical or scanning electron microscope. In special cases, the objective of the examination may require the development of less detail than in other cases but, under nearly all conditions, the proper selection and preparation of the specimen is of major importance. Because of the diversity in available equipment and the wide variety of problems encountered, the following text presents for the guidance of the metallographer only those practices which experience has shown are generally satisfactory; it cannot and does not describe the variations in technique required to solve individual specimen preparation problems. Note 1—For a more extensive description of various metallographic techniques, refer to Samuels, L. E., Metallographic Polishing by Mechanical Methods, American Society for Metals (ASM) Metals Park, OH, 3rd Ed., 1982; Petzow, G., Metallographic Etchin...

  7. Preparation and characterization of Bi-2223 tapes

    International Nuclear Information System (INIS)

    Hense, K.; Kirchmayr, H.; Kovac, P.; Lackner, R.; Mueller, M.; Pachla, W.; Pitel, J.; Polak, M.; Usak, P.

    2003-01-01

    In a concerted action between Austrian, Slovakian and Polish research institutes Bi-2223 tapes have been prepared and characterized by different physical methods. Metallographic studies by optical as well as electron microscopy, measurements of critical current (angle dependent) and losses have been performed. Properties of individual filaments extracted from multifilamentary tapes were also studied. Uniformity of local I C of these filaments were considerably lower than that of the whole tape. This indicates that improvement of filament homogeneity could improve the over all J C in tapes. The application of these tapes for optimized magnet coils will also be discussed. From these investigations a better understanding of the mechanisms, limiting the critical current could be achieved and more optimized preparation methods can be envisioned

  8. Surface texture of resin-modified glass ionomer cements: effects of finishing/polishing time.

    Science.gov (United States)

    Yap, A U J; Ong, S B; Yap, W Y; Tan, W S; Yeo, J C

    2002-01-01

    This study compared the surface texture of resin-modified glass ionomer cements after immediate and delayed finishing with different finishing/polishing systems. Class V preparations were made on the buccal and lingual/palatal surfaces of 64 freshly extracted teeth. The cavities on each tooth were restored with Fuji II LC (GC) and Photac-Fil Quick (3M-ESPE) according to manufacturers' instructions. Immediately after light-polymerization, gross finishing was done with 8-fluted tungsten carbide burs. The teeth were then randomly divided into four groups of 16 teeth. Half of the teeth in each group were finished immediately, while the remaining half were finished after one-week storage in distilled water at 37 degrees C. The following finishing/polishing systems were employed: (a) Robot Carbides; (b) Super-Snap system; (c) OneGloss and (d) CompoSite Polishers. The mean surface roughness (microm; n=8) in vertical (RaV) and horizontal (RaH) axis was measured using a profilometer. Data was subjected to ANOVA/Scheffe's tests and Independent Samples t-test at significance level 0.05. Ra values were generally lower in both vertical and horizontal axis with delayed finishing/polishing. Although significant differences in RaV and RaH values were observed among several systems with immediate finishing/polishing, only one (Fuji II LC: RaH - Super-Snap < Robot Carbides) was observed with delayed finishing.

  9. Gloss and surface roughness produced by polishing kits on resin composites.

    Science.gov (United States)

    Sadidzadeh, Ramtin; Cakir, Deniz; Ramp, Lance C; Burgess, John O

    2010-08-01

    To compare in vitro the surface roughness (Ra) and gloss (G) produced by three conventional and one experimental polishing kits on four resin composites. 24 discs were prepared (d = 12 mm, t = 4 mm) for each resin composite: Filtek Supreme Plus Body/A2 (FSB), Yellow Translucent (FST), Heliomolar/A2 (HM), and EsthetX/A2 (EX) following the manufacturers' instructions. They were finished with 320 grit silicon carbide paper for 80 seconds each. Polishing systems: Sof-Lex, Enhance-Pogo, Astropol and Experimental Discs/EXL-695, were applied following manufacturers' instructions. Each specimen was ultrasonically cleaned with distilled water and dried. Gloss and Ra were measured with a small area glossmeter (Novo-curve) and non-contact profilometer (Proscan 2000) following ISO 4288, respectively. The results were evaluated by two-way ANOVA followed by separate one-way ANOVA and Tukey/Kramer test (P = 0.05). There was a significant interaction of surface roughness and gloss between the composites and polishing systems (P gloss was obtained for FSB composite polished with the Experimental kit. The experimental polishing system produced smoothest surfaces (P gloss (P < 0.05).

  10. Investigation of the sample preparation and curing treatment effects on mechanical properties and bioactivity of silica rich metakaolin geopolymer

    International Nuclear Information System (INIS)

    Catauro, M.; Bollino, F.; Papale, F.; Lamanna, G.

    2014-01-01

    In many biomedical applications both the biological and mechanical behaviours of implants are of relevant interest; in the orthopaedic field, for example, favourable bioactivity and biocompatibility capabilities are necessary, but at the same time the mechanical characteristics of the implants must be such as to allow one to support the body weight. In the present work, the authors have examined the application of geopolymers with composition H 24 AlK 7 Si 31 O 79 and ratio Si/Al = 31 to be used in biomedical field, considering two different preparation methods: one of the activators (KOH) has been added as pellets in the potassium silicate solution, in the other as a water solution with 8 M concentration. Moreover, a different water content was used and only some of the synthesized samples were heat treated. The chemical and microstructural characterizations of those materials have been carried out by Fourier transform infrared spectroscopy (FT-IR) and scanning electron microscopy (SEM). Subsequently, the effects of the adopted preparation on the mechanical and biological properties have been studied: compressive strength tests have demonstrated that more fragile specimens were obtained when KOH was added as a solution. The bioactivity was successfully evaluated with the soaking of the samples in a simulated body fluid (SBF) for 3 weeks. The formation of a layer of hydroxyapatite on the surface of the materials has been shown both by SEM micrographs and EDS analyses. - Highlights: • Rich metakaolin geopolymer activated with KOH/K 2 SiO 3 and thermal treatment • Mechanical and bioactivity test to evaluate consolidation and bone bonding ability • Order of addition of reactants and thermal treatment influence mechanical properties

  11. Investigation of the sample preparation and curing treatment effects on mechanical properties and bioactivity of silica rich metakaolin geopolymer

    Energy Technology Data Exchange (ETDEWEB)

    Catauro, M., E-mail: michelina.catauro@unina2.it; Bollino, F.; Papale, F.; Lamanna, G.

    2014-03-01

    In many biomedical applications both the biological and mechanical behaviours of implants are of relevant interest; in the orthopaedic field, for example, favourable bioactivity and biocompatibility capabilities are necessary, but at the same time the mechanical characteristics of the implants must be such as to allow one to support the body weight. In the present work, the authors have examined the application of geopolymers with composition H{sub 24}AlK{sub 7}Si{sub 31}O{sub 79} and ratio Si/Al = 31 to be used in biomedical field, considering two different preparation methods: one of the activators (KOH) has been added as pellets in the potassium silicate solution, in the other as a water solution with 8 M concentration. Moreover, a different water content was used and only some of the synthesized samples were heat treated. The chemical and microstructural characterizations of those materials have been carried out by Fourier transform infrared spectroscopy (FT-IR) and scanning electron microscopy (SEM). Subsequently, the effects of the adopted preparation on the mechanical and biological properties have been studied: compressive strength tests have demonstrated that more fragile specimens were obtained when KOH was added as a solution. The bioactivity was successfully evaluated with the soaking of the samples in a simulated body fluid (SBF) for 3 weeks. The formation of a layer of hydroxyapatite on the surface of the materials has been shown both by SEM micrographs and EDS analyses. - Highlights: • Rich metakaolin geopolymer activated with KOH/K{sub 2}SiO{sub 3} and thermal treatment • Mechanical and bioactivity test to evaluate consolidation and bone bonding ability • Order of addition of reactants and thermal treatment influence mechanical properties.

  12. Improved mechanical and functional properties of elastomer/graphite nanocomposites prepared by latex compounding

    International Nuclear Information System (INIS)

    Yang Jian; Tian Ming; Jia Qingxiu; Shi Junhong; Zhang Liqun; Lim Szuhui; Yu Zhongzhen; Mai Yiuwing

    2007-01-01

    The facile latex approach has been adopted to finely incorporate graphite nanosheets into elastomeric polymer matrix to obtain high-performance elastomeric nanocomposites with improved mechanical properties and functional properties. Scanning electron microscopy, transmission electron microscopy and X-ray diffraction experiments show that the nanostructures of the final nanocomposites exhibit a high degree of exfoliation and intercalation of graphite in the nitrile-butadiene rubber (NBR) matrix. Mechanical and dynamic-mechanical tests demonstrate that the NBR/graphite nanocomposites possess greatly increased elastic modulus and tensile strength, and desirably strong interfaces. The unexpected self-crosslinking of elastomer/graphite nanocomposites was discovered and then verified by oscillating disc rheometry and equilibrium swelling experiments. After critically examining various polymer types by X-ray photoelectron spectroscopy, electron spin resonance and Fourier transform infrared spectroscopy, a radical initiation mechanism was proposed to explain the self-crosslinking reaction. These NBR/graphite nanocomposites possess significantly improved wear resistance and gas barrier properties, and superior electrical/thermal conductivity. Such versatile functional properties make NBR nanocomposites a promising new class of advanced materials

  13. FeSiBAlNiMo High Entropy Alloy Prepared by Mechanical Alloying

    Czech Academy of Sciences Publication Activity Database

    Bureš, R.; Hadraba, Hynek; Fáberová, M.; Kollár, P.; Füzer, J.; Roupcová, Pavla; Strečková, M.

    2017-01-01

    Roč. 131, č. 4 (2017), s. 771-773 ISSN 0587-4246 R&D Projects: GA ČR(CZ) GA14-25246S Institutional support: RVO:68081723 Keywords : Entropy * Mechanical alloying * Nanocrystals * Sintering Subject RIV: JG - Metallurgy OBOR OECD: Materials engineering Impact factor: 0.469, year: 2016

  14. Improved mechanical and functional properties of elastomer/graphite nanocomposites prepared by latex compounding

    Energy Technology Data Exchange (ETDEWEB)

    Yang Jian [Key Laboratory for Nano-materials, Beijing University of Chemical Technology, Ministry of Education of China, Beijing 100029 (China); Key Laboratory on Preparation and Processing of Novel Polymer Materials, Beijing University of Chemical Technology, Beijing 100029 (China); Tian Ming [Key Laboratory for Nano-materials, Beijing University of Chemical Technology, Ministry of Education of China, Beijing 100029 (China); Jia Qingxiu [Key Laboratory on Preparation and Processing of Novel Polymer Materials, Beijing University of Chemical Technology, Beijing 100029 (China); Shi Junhong [Key Laboratory for Nano-materials, Beijing University of Chemical Technology, Ministry of Education of China, Beijing 100029 (China); Zhang Liqun [Key Laboratory for Nano-materials, Beijing University of Chemical Technology, Ministry of Education of China, Beijing 100029 (China); Key Laboratory on Preparation and Processing of Novel Polymer Materials, Beijing University of Chemical Technology, Beijing 100029 (China)], E-mail: zhanglq@mail.buct.edu.cn; Lim Szuhui; Yu Zhongzhen [Centre for Advanced Materials Technology (CAMT), School of Aerospace, Mechanical and Mechatronic Engineering (J07), University of Sydney, Sydney, NSW 2006 (Australia); Mai Yiuwing [Centre for Advanced Materials Technology (CAMT), School of Aerospace, Mechanical and Mechatronic Engineering (J07), University of Sydney, Sydney, NSW 2006 (Australia)], E-mail: y.mai@usyd.edu.au

    2007-10-15

    The facile latex approach has been adopted to finely incorporate graphite nanosheets into elastomeric polymer matrix to obtain high-performance elastomeric nanocomposites with improved mechanical properties and functional properties. Scanning electron microscopy, transmission electron microscopy and X-ray diffraction experiments show that the nanostructures of the final nanocomposites exhibit a high degree of exfoliation and intercalation of graphite in the nitrile-butadiene rubber (NBR) matrix. Mechanical and dynamic-mechanical tests demonstrate that the NBR/graphite nanocomposites possess greatly increased elastic modulus and tensile strength, and desirably strong interfaces. The unexpected self-crosslinking of elastomer/graphite nanocomposites was discovered and then verified by oscillating disc rheometry and equilibrium swelling experiments. After critically examining various polymer types by X-ray photoelectron spectroscopy, electron spin resonance and Fourier transform infrared spectroscopy, a radical initiation mechanism was proposed to explain the self-crosslinking reaction. These NBR/graphite nanocomposites possess significantly improved wear resistance and gas barrier properties, and superior electrical/thermal conductivity. Such versatile functional properties make NBR nanocomposites a promising new class of advanced materials.

  15. Ceramic core–shell composites with modified mechanical properties prepared by thermoplastic co-extrusion

    Czech Academy of Sciences Publication Activity Database

    Kaštyl, J.; Chlup, Zdeněk; Clemens, F.; Trunec, M.

    2015-01-01

    Roč. 35, č. 10 (2015), s. 2873-2881 ISSN 0955-2219 R&D Projects: GA MŠk(CZ) ED1.1.00/02.0068 Institutional support: RVO:68081723 Keywords : Alumina * Zirconia toughened alumina * Co-extrusion * Composite * Mechanical properties1 Subject RIV: JH - Ceramics, Fire-Resistant Materials and Glass Impact factor: 2.933, year: 2015

  16. Powder metallurgy preparation of Al-Cu-Fe quasicrystals using mechanical alloying and Spark Plasma Sintering

    Czech Academy of Sciences Publication Activity Database

    Novák, P.; Kubatík, Tomáš František; Vystrčil, J.; Hendrych, R.; Kříž, J.; Mlynár, J.; Vojtěch, D.

    2014-01-01

    Roč. 52, September (2014), s. 131-137 ISSN 0966-9795 Institutional support: RVO:61389021 Keywords : Nanostructure intermetallics * Ternary alloys systems * Mechanical alloying and milling * Sintering * Diffraction Subject RIV: JG - Metallurgy Impact factor: 2.131, year: 2014 http://www.sciencedirect.com/science/article/pii/S0966979514001198#

  17. Microstructure and mechanical strength of near- and sub-micrometre grain size copper prepared by spark plasma sintering

    DEFF Research Database (Denmark)

    Zhu, K. N.; Godfrey, A.; Hansen, Niels

    2017-01-01

    Spark plasma sintering (SPS) has been used to prepare fully dense samples of copper in a fully recrystallized condition with grain sizes in the near- and sub-micrometre regime. Two synthesis routes have been investigated to achieve grain size control: (i) SPS at different temperatures from 800...... transmission electron microscope, and on electron back-scatter diffraction studies, confirms the samples are in a nearly fully recrystallized condition, with grains that are dislocation-free, and have a random texture, with a high fraction of high angle boundaries. The mechanical strength of the samples has...

  18. Studies of the composition, mechanical and electrical properties of N-doped carbon films prepared by DC-MFCAD

    International Nuclear Information System (INIS)

    Wen, F.; Huang, N.; Leng, Y.X.; Wang, J.; Sun, H.; Li, Y.J.; Wang, Z.W.

    2006-01-01

    N-doped carbon films were prepared on Si(1 0 0) and Ti-6Al-4V substrates using direct current magnetically filtered cathodic arc deposition (DC-MFCAD) at room temperature for various different N 2 pressures. The structure and composition of the films were characterized by Raman spectroscopy and X-ray photoelectron spectroscopy (XPS). Ball-on-disk and microhardness tests were used to characterize the mechanical properties of the films, and Hall effect tests were employed to study the electrical properties

  19. The preparation and mechanical properties of Al-containing a-C : H thin films

    International Nuclear Information System (INIS)

    Zhang Guangan; Yan Pengxun; Wang Peng; Chen Youming; Zhang Junyan

    2007-01-01

    Al-containing hydrogenated amorphous carbon (Al-C : H) films were deposited on silicon substrates using a mid frequency magnetron sputtering Al target in an argon and methane gas mixture. The composition, surface morphology, hardness and friction coefficient of the films were characterized using x-ray photoelectron spectroscopy, atomic force microscopy, nanoindentation and tribological tester. The Al-C : H films deposited at low CH 4 content show high surface roughness, low hardness and high friction coefficient, similar to metallic Al films; in contrast, the Al-C : H films prepared under high CH 4 content indicate low surface roughness, high hardness and low friction coefficient, close to that of hard a-C : H films as wear-resistance films

  20. Multifunctional foaming agent to prepare aluminum foam with enhanced mechanical properties

    Science.gov (United States)

    Li, Xun; Liu, Ying; Ye, Jinwen; An, Xuguang; Ran, Huaying

    2018-03-01

    In this paper, CuSO4 was used as foaming agent to prepare close cell Aluminum foam(Al foam) at the temperature range of 680 °C ∼ 758 °C for the first time. The results show that CuSO4 has multifunctional such as, foaming, viscosity increasing, reinforcement in Al matrix, it has a wide decomposition temperature range of 641 °C ∼ 816 °C, its sustain-release time is 5.5 min at 758 °C. The compression stress and energy absorption of CuSO4-Al foam is 6.89 Mpa and 4.82 × 106 J m‑3(compression strain 50%), which are 77.12% and 99.17% higher than that of TiH2-Al foam at the same porosity(76% in porosity) due to the reinforcement in Al matrix and uniform pore dispersion.

  1. Preparation and Mechanical Properties of Fiber Reinforced PLA for 3D Printing Materials

    Science.gov (United States)

    Li, Xionghao; Ni, Zhongjin; Bai, Shuyang; Lou, Baiyang

    2018-03-01

    The cellulose prepared by means of TEMPO oxidation method and glass fibre was blended with PLA respectively, and were spun into enhanced PLA wires. This study evaluates the wire rods that is from extruder is suitable for FDM printing by various physical characterization tests to determine their feasibility as a 3D printing filament materials. The cellulose and glass fibre is blended with PLA and spun into the reinforced PLA filament respectively, which is applied to FDM printing technology. The results showed that the intensity of strike resistant of the reinforced PLA filament made from cellulose and PLA is 34% to 60% higher than the PLA filament, meanwhile the tensile strength is 43% to 52% higher than the pure one. The other enhanced PLA filament is 13% to 35% higher than the PLA filament in intensity of strike resistant, and the tensile strength is 54% to 61% higher than the pure one.

  2. A comparative study of structural and mechanical properties of Al–Cu composites prepared by vacuum and microwave sintering techniques

    Directory of Open Access Journals (Sweden)

    Penchal Reddy Matli

    2018-04-01

    Full Text Available In this paper, the aluminum metal matrix composite reinforced with copper particulates (3, 6 and 9 vol.% were fabricated by high energy ball milling, followed by vacuum sintering (VS and microwave sintering techniques (MS separately. The effects of Cu content and preparation methods on the microstructure and compression mechanical behavior of Al–Cu matrix composites were investigated. The microstructural characterizations revealed a homogeneous distribution of Cu particles in the Al matrix and also fine microstructures of microwave sintered samples. The microwave sintered specimen exhibited the highest hardness and better mechanical properties compared to vacuum sintered specimens. Furthermore, the hardness and compressive strength increased 137.2% and 30.3% for the microwave sintered Al–9 vol.% Cu composite, respectively. The increase in mechanical properties with the increasing volume fraction of Cu particulates can be ascribed to the presence of harder Cu particles reinforcement. The developed materials of the microwave sintered Al–Cu composite in this investigation could be successfully used for industrial applications due to improved mechanical properties. Keywords: Al matrix composites, Microwave sintering, Microstructure, Mechanical behavior

  3. APS 3D: a new benchmark in aspherical polishing

    Science.gov (United States)

    Gauch, Daniel; Mikulic, Dalibor; Veit, Christian

    2017-10-01

    The APS 3D system performs polishing and form correction in one step in order to reduce overall process time, reduce the number of polishing steps required and eliminate the need for highly skilled operators while providing a repeatable polishing process. This new 3D Polishing system yields better surface quality, and a better slope error, automatically determining the optimum speeds, feed rates and polish pressures to achieve a deterministic process based on the required quality parameters input by the operator. The process flow is always the same to ensure consistent quality and target quality values are defined before polishing begins.

  4. Mechanical properties of silicon oxynitride thin films prepared by low energy ion beam assisted deposition

    International Nuclear Information System (INIS)

    Shima, Yukari; Hasuyama, Hiroki; Kondoh, Toshiharu; Imaoka, Yasuo; Watari, Takanori; Baba, Koumei; Hatada, Ruriko

    1999-01-01

    Silicon oxynitride (SiO x N y ) films (0.1-0.7 μm) were produced on Si (1 0 0), glass and 316L stainless steel substrates by ion beam assisted deposition (IBAD) using Si evaporation and the concurrent bombardment with a mixture of 200 eV N 2 and Ar, or O 2 and Ar ions. Adhesion was evaluated by pull-off tests. Film hardness was measured by a nanoindentation system with AFM. The measurement of internal stress in the films was carried out by the Stoney method. The film structure was examined by GXRD. XPS was employed to measure the composition of films and to analyze the chemical bonds. The dependence of mechanical properties on the film thickness and the processing temperature during deposition was studied. Finally, the relations between the mechanical properties of the films and the correlation with corrosion-protection ability of films are discussed and summarized

  5. Nanocrystalline Al7075+1 wt % Zr Alloy Prepared Using Mechanical Milling and Spark Plasma Sintering.

    Czech Academy of Sciences Publication Activity Database

    Molnárová, O.; Málek, P.; Veselý, J.; Šlapáková, M.; Minárik, P.; Lukáč, František; Chráska, Tomáš; Novák, P.; Průša, F.

    2017-01-01

    Roč. 10, č. 9 (2017), č. článku 1105. ISSN 1996-1944 R&D Projects: GA ČR(CZ) GA15-15609S Institutional support: RVO:61389021 Keywords : gas atomization * mechanical milling * spark plasma sintering * microstructure * microhardness * recrystallization Subject RIV: JG - Metallurgy OBOR OECD: Materials engineering Impact factor: 2.654, year: 2016 http://www.readcube.com/articles/10.3390/ma10091105

  6. Mechanical and thermal expansion properties of β-eucryptite prepared by sol-gel methods and hot pressing

    International Nuclear Information System (INIS)

    Xia, L.; Wen, G.W.; Qin, C.L.; Wang, X.Y.; Song, L.

    2011-01-01

    Research highlights: → Dense LAS glass-ceramics were fabricated by sol-gel and hot pressing technique. → The LAS glass-ceramics have relative good mechanical properties. → The negative thermal expansion behavior of LAS glass-ceramics was investigated. -- Abstract: The microstructures, mechanical properties and thermal expansion behavior of monolithic lithium aluminosilicate glass-ceramics, prepared by sol-gel method and hot pressing, were investigated by using X-ray diffraction, scanning and transmission electron microscopies, three-point bend tests and dilatometry. β-eucryptite appeared as main phase in the monolithic lithium aluminosilicate glass-ceramics. The glass ceramics exhibited high relative densities and the average flexural strength and fracture toughness values were 154 MPa and 2.46 MPa m 1/2 , respectively. The lithium aluminosilicate glass-ceramics hot pressed 1300 and 1350 o C demonstrated negative coefficient of thermal expansion, which was affected by amount and type of crystalline phases.

  7. Synthesis mechanism of an Al-Ti-C grain refiner master alloy prepared by a new method

    Science.gov (United States)

    Zhang, B. Q.; Lu, L.; Lai, M. O.; Fang, H. S.; Ma, H. T.; Li, J. G.

    2003-08-01

    The mechanisms of in-situ synthesis of an Al-Ti-C grain-refiner master alloy, prepared by adding a powder mixture of potassium titanium fluoride and carbon into an aluminum melt, have been systematically studied. It was found that vigorous reactions occurred at the initial stage of reaction and then slowed down. After about 20 minutes, the reactions, which led the formation of blocky titanium aluminides and submicron titanium carbides in the aluminum matrix, appeared to reach completion. Potassium titanium fluoride reacted with aluminum and carbon at 724 °C and 736 °C, respectively, resulting in the formation of titanium aluminides and titanium carbides in the aluminum matrix as well as in the formation of a low-melting-point slag of binary potassium aluminofluorides. The reaction between potassium titanium fluoride and carbon is believed to be the predominant mechanism in the synthesis of TiC by this method.

  8. Microstructure and mechanical properties of Al/Fe-aluminide in-situ composite prepared by reactive stir casting route

    International Nuclear Information System (INIS)

    Chatterjee, Subhranshu; Sinha, Arijit; Das, Debdulal; Ghosh, Sumit; Basumallick, Amitava

    2013-01-01

    Iron aluminide particulate reinforced aluminium composites were prepared by a simple liquid metal stir casting route. The particulate intermetallic reinforcements were formed by in-situ reaction between molten aluminium and a rotating mild steel stirrer at 800 °C. X-ray diffraction studies were carried out to identify the types of iron aluminide particulates present in the as cast composite. Compositional variations of the composite samples were estimated with the aid of energy dispersive spectroscopy. The microstructural features of the composite were studied with respect to different heat treatment schedules and deformation conditions. Microhardness and nanoindentation measurements were also carried out to assess the micromechanical behaviour e.g., hardness and elastic modulus in micrometric length scale of the composite samples. Tensile tests and fractographic analysis were performed to estimate the mechanical properties and determine the mode of failure of the samples. The microstructure and mechanical properties of the composite samples were correlated and discussed

  9. Structural and mechanical properties of nc-TiC/a-C:H nanocomposite film prepared by dual plasma technique

    International Nuclear Information System (INIS)

    Wang Yaohui; Zhang Xu; Wu Xianying; Li Qiang; Zhang Huixing; Zhang Xiaoji

    2008-01-01

    Nanocomposite nc-TiC/a-C:H film, with an unusual combination of superhardness, high elastic modulus and high elastic recovery, are prepared by using the dual plasma technique. The effects of the filter coil current on the compositional, structural and mechanical properties of the nc-TiC/a-C:H films have been investigated. X-ray photoelectron spectroscopy (XPS) and Raman analyses show that deposition rate, composition and nanostructure of the nc-TiC/a-C:H films could be changed by varying the filter coil current. Fortunately, by selecting the proper value for the filter coil current, 2.5 A, one could remarkably enhance mechanical properties of films such as the superhardness (66.4 GPa), the high elastic modulus (510 GPa) and the high elastic recovery (83.3%)

  10. Cone-beam computed tomography analysis of the apical third of curved roots after mechanical preparation with different automated systems

    International Nuclear Information System (INIS)

    Oliveira, Cesar Augusto Pereira; Pascoalato, Cristina; Meurer, Maria Ines; Silva, Silvio Rocha Correa

    2009-01-01

    The present study evaluated by cone-beam computed tomography (CBCT) the apical canal transportation and centralizing ability of different automated systems after root canal preparation. The mesiobuccal canals of maxillary first molars (n=10 per group) were prepared with: GI - reciprocating system with K-Flexofile; GII - reciprocating system with NiTiFlex files; GIII - rotary system with K3 instruments; GIV - rotary system with RaCe instruments. CBCT scans were taken before and after biomechanical preparation up to a 40.02 diameter. Canal transportation was determined by measuring the smallest distance between the inner canal walls and the mesial and distal sides of the root. The centralization ability corresponded to the difference between the measurements from transportation evaluation, using the linear voxel to voxel method of analysis. The mean transportation was 0.06 ± 0.14 mm, with a tendency to deviate to the mesial side of the root (n=22), with no statistically significant difference among the groups (p=0.4153). The mean centralization index was 0.15 ± 0.65 also without statistically significant difference among the groups (p=0.0881). It may be concluded that apical canal transportation and centralization ability were not influenced by the type of mechanical movement and instruments used. (author)

  11. Cone-beam computed tomography analysis of the apical third of curved roots after mechanical preparation with different automated systems

    Energy Technology Data Exchange (ETDEWEB)

    Oliveira, Cesar Augusto Pereira; Pascoalato, Cristina [University of Southern Santa Catarina (UNISUL), Tubarao, SC (Brazil); Meurer, Maria Ines [Federal University of Santa Catarina (UFSC), Florianopolis, SC (Brazil); Silva, Silvio Rocha Correa, E-mail: silvio@foar.unesp.b [Sao Paulo State University (UNESP), Araraquara, SP (Brazil)

    2009-07-01

    The present study evaluated by cone-beam computed tomography (CBCT) the apical canal transportation and centralizing ability of different automated systems after root canal preparation. The mesiobuccal canals of maxillary first molars (n=10 per group) were prepared with: GI - reciprocating system with K-Flexofile; GII - reciprocating system with NiTiFlex files; GIII - rotary system with K3 instruments; GIV - rotary system with RaCe instruments. CBCT scans were taken before and after biomechanical preparation up to a 40.02 diameter. Canal transportation was determined by measuring the smallest distance between the inner canal walls and the mesial and distal sides of the root. The centralization ability corresponded to the difference between the measurements from transportation evaluation, using the linear voxel to voxel method of analysis. The mean transportation was 0.06 +- 0.14 mm, with a tendency to deviate to the mesial side of the root (n=22), with no statistically significant difference among the groups (p=0.4153). The mean centralization index was 0.15 +- 0.65 also without statistically significant difference among the groups (p=0.0881). It may be concluded that apical canal transportation and centralization ability were not influenced by the type of mechanical movement and instruments used. (author)

  12. Preparation of a Bimetal Using Mechanical Alloying for Environmental or Industrial Use

    Science.gov (United States)

    Quinn, Jacqueline; Geiger, Cherie; Clausen, Christian

    2013-01-01

    Following the 1976 Toxic Substances Control Act ban on their manufacture, PCBs remain an environmental threat. PCBs are known to bio-accumulate and concentrate in fatty tissues. Further complications arise from the potential for contamination of commercial mixtures with other more toxic chlorinated compounds such as polychlorinated dibenzodioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs). Until recently, only one option was available for the treatment of PCB-contaminated materials: incineration. This may prove to be more detrimental to the environment than the PCBs themselves due to the potential for formation of PCDDs. Metals have been used for the past ten years for the remediation of halogenated solvents and other contaminants in the environment; however, zero-valent metals alone do not possess the activity required to dehalogenate PCBs. Palladium has been shown to act as an excellent catalyst for the dechlorination of PCBs with active metals. This invention is a method for the production of a palladium/magnesium bimetal capable of dechlorinating PCBs using mechanical milling/mechanical alloying. Other base metals and catalysts may also be alloyed together (e.g., nickel or zinc) to create a similarly functioning catalyst system. Several bimetal catalyst systems currently can be used for processes such as hydrogen peroxide synthesis, oxidation of ethane, selective oxidation, hydrogenation, and production of syngas for further conversion to clean fuels. The processes for making these bimetal catalysts often involve vapor deposition. This technology provides an alternative to vapor deposition that may provide equally active catalysts. A hydrogenation catalyst including a base material coated with a catalytic metal is made using mechanical milling techniques. The hydrogenation catalysts are used as an excellent catalyst for the dehalogenation of contaminated compounds and the remediation of other industrial compounds. The mechanical milling technique is

  13. Preparation and mechanical properties of photo-crosslinked poly(trimethylene carbonate) and nano-hydroxyapatite composites.

    Science.gov (United States)

    Geven, Mike A; Barbieri, Davide; Yuan, Huipin; de Bruijn, Joost D; Grijpma, Dirk W

    2015-01-01

    Composite materials of photo-crosslinked poly(trimethylene carbonate) and nanoscale hydroxyapatite were prepared and their mechanical characteristics for application as orbital floor implants were assessed. The composites were prepared by solvent casting poly(trimethylene carbonate) macromers with varying amounts of nano-hydroxyapatite and subsequent photo-crosslinking. The incorporation of the nano-hydroxyapatite into the composites was examined by thermogravimetric analysis, scanning electron microscopy and gel content measurements. The mechanical properties were investigated by tensile testing and trouser tearing experiments. Our results show that nano-hydroxyapatite particles can readily be incorporated into photo-crosslinked poly(trimethylene carbonate) networks. Compared to the networks without nano-hydroxyapatite, incorporation of 36.3 wt.% of the apatite resulted in an increase of the E modulus, yield strength and tensile strength from 2.2 MPa to 51 MPa, 0.5 to 1.4 N/mm2 and from 1.3 to 3.9 N/mm2, respectively. We found that composites containing 12.4 wt.% nano-hydroxyapatite had the highest values of strain at break, toughness and average tear propagation strength (376% , 777 N/mm2 and 3.1 N/mm2, respectively).

  14. Chitosan-Based Coating with Antimicrobial Agents: Preparation, Property, Mechanism, and Application Effectiveness on Fruits and Vegetables

    Directory of Open Access Journals (Sweden)

    Yage Xing

    2016-01-01

    Full Text Available Chitosan coating is beneficial to maintaining the storage quality and prolonging the shelf life of postharvest fruits and vegetables, which is always used as the carrier film for the antimicrobial agents. This review focuses on the preparation, property, mechanism, and application effectiveness on the fruits and vegetables of chitosan-based coating with antimicrobial agents. Chitosan, derived by deacetylation of chitin, is a modified and natural biopolymer as the coating material. In this article, the safety and biocompatible and antimicrobial properties of chitosan were introduced because these attributes are very important for its application. The methods to prepare the chitosan-based coating with antimicrobial agents, such as essential oils, acid, and nanoparticles, were developed by other researchers. Meanwhile, the application of chitosan-based coating is mainly due to its antimicrobial activity and other functional properties, which were investigated, introduced, and analyzed in this review. Furthermore, the surface and mechanical properties were also investigated by researchers and concluded in this article. Finally, the effects of chitosan-based coating on the storage quality, microbial safety, and shelf life of fruits and vegetables were introduced. Their results indicated that chitosan-based coating with different antimicrobial agents would probably have wide prospect in the preservation of fruits and vegetables in the future.

  15. Preparation of a high strength Al–Cu–Mg alloy by mechanical alloying and press-forming

    International Nuclear Information System (INIS)

    Tang Huaguo; Cheng Zhiqiang; Liu Jianwei; Ma Xianfeng

    2012-01-01

    Highlights: ► A high strength aluminum alloy of Al–2 wt.%Mg–2 wt.%Cu has been prepared by mechanical alloying and press-forming. ► The alloy only consists of solid solution α-Al. ► The grains size of α-Al was about 300 nm–5 μm. ► The solid solution strengthening and the grain refinement strengthening are the main reasons for such a high strength. - Abstract: A high strength aluminum alloy, with the ratio of 96 wt.%Al–2 wt.%Mg–2 wt.%Cu, has been prepared by mechanical alloying and press-forming. The alloy exhibited a high tensile strength of 780 MPa and a high microhardness of 180 HV. X-ray diffraction characterizations confirmed that the alloy only consists of a solid solution α-Al. Microstructure characterizations revealed that the grain size of α-Al was about 300 nm–5 μm. The solid solution strengthening and the grain refinement strengthening were considered to be the reason for such a high strength.

  16. Preparation of a high strength Al-Cu-Mg alloy by mechanical alloying and press-forming

    Energy Technology Data Exchange (ETDEWEB)

    Tang Huaguo [State Key Laboratory of Rare Earth Utilization, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022 (China); Cheng Zhiqiang [College of Resources and Environment, Jilin Agricultural University, Changchun 130118 (China); Liu Jianwei [State Key Laboratory of Rare Earth Utilization, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022 (China); Ma Xianfeng, E-mail: xfma@ciac.jl.cn [State Key Laboratory of Rare Earth Utilization, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022 (China)

    2012-07-30

    Highlights: Black-Right-Pointing-Pointer A high strength aluminum alloy of Al-2 wt.%Mg-2 wt.%Cu has been prepared by mechanical alloying and press-forming. Black-Right-Pointing-Pointer The alloy only consists of solid solution {alpha}-Al. Black-Right-Pointing-Pointer The grains size of {alpha}-Al was about 300 nm-5 {mu}m. Black-Right-Pointing-Pointer The solid solution strengthening and the grain refinement strengthening are the main reasons for such a high strength. - Abstract: A high strength aluminum alloy, with the ratio of 96 wt.%Al-2 wt.%Mg-2 wt.%Cu, has been prepared by mechanical alloying and press-forming. The alloy exhibited a high tensile strength of 780 MPa and a high microhardness of 180 HV. X-ray diffraction characterizations confirmed that the alloy only consists of a solid solution {alpha}-Al. Microstructure characterizations revealed that the grain size of {alpha}-Al was about 300 nm-5 {mu}m. The solid solution strengthening and the grain refinement strengthening were considered to be the reason for such a high strength.

  17. Formation, decomposition and cesium adsorption mechanisms of highly alkali-tolerant nickel ferrocyanide prepared by interfacial synthesis

    International Nuclear Information System (INIS)

    Ichikawa, Tsuneki; Yamada, Kazuo; Osako, Masahiro; Haga, Kazuko

    2017-01-01

    Highly alkali-tolerant nickel ferrocyanide was prepared as an adsorbent for preventing the leaching of radioactive cesium from municipal solid waste incinerator fly ash containing large amounts of calcium hydroxide and potassium chloride, which act as an alkaline source and the suppressor for cesium adsorption, respectively. Nickel ferrocyanide prepared by contacting concentrated nickel and ferrocyanide solutions without mixing adsorbed cesium ions in alkaline conditions even the concentration of coexisting potassium ions was more than ten thousand times higher than that of the cesium ions. Large particles of nickel ferrocyanide slowly grew at the interface between the two solutions, which reduced the surface energy of the particles and therefore increased the alkali tolerance. The interfacially-synthesized nickel ferrocyanide was possible to prevent the leaching of radioactive cesium from cement-solidified fly ash for a long period. The mechanisms of the formation, selective cesium adsorption, and alkali-induced decomposition of the nickel ferrocyanide were elucidated. Comparison of the cesium adsorption mechanism with that of the other adsorbents revealed that an adsorbent can selectively adsorb cesium ions without much interference from potassium ions, if the following conditions are fulfilled. 1) The adsorption site is small enough for supplying sufficient electrostatic energy for the dehydration of ions adsorbed. 2) Both the cesium and potassium ions are adsorbed as dehydrated ions. 3) The adsorption site is flexible enough for permitting the penetration of dehydrated ions with the size comparable to that of the site. (author)

  18. A survey of the mechanical properties of concrete for structural purposes prepared on construction sites

    Directory of Open Access Journals (Sweden)

    R. R. J. RIBEIRO

    Full Text Available Abstract This paper aims to study the concrete dosage conditions for structural purposes in construction sitesl, and the impacts of non-compliance of structural concrete for structural safety, having as study case the city of Angicos / RN. Were analyzed the dynamic elasticity modulus, static elasticity modulus and the compressive strength of concrete samples. Was conducted to collect the survey data, a field research aiming to gather information about dosage of concrete used in the works, as well as the collection of cylindrical specimens of 150 mm diameter by 300 mm of height, prepared according to practice of those professionals. The study indicated a clear necessity to reflection on the subject, since there is no concern, or even, a lack of knowledge by the interviewed professionals regarding the care and procedures necessary for the production of concrete with satisfactory quality, once at least 50% of evaluated construction sites presented compressive strength lower than 20 MPa, minimal strength to structural concrete, as recommended by ABNT-NBR 6118:2014.

  19. Mechanical, Microstructure and Surface Characterizations of Carbon Fibers Prepared from Cellulose after Liquefying and Curing

    Directory of Open Access Journals (Sweden)

    Xiaojun Ma

    2013-12-01

    Full Text Available In this study, Cellulose-based carbon fibers (CBCFs were prepared from cellulose after phenol liquefaction and curing. The characteristics and properties of CBCFs were examined by scanning electron microscopy (SEM, Fourier transform infrared spectroscopy (FTIR, X-ray diffraction (XRD, Raman spectroscopy and X-ray photoelectron spectroscopy (XPS. The results showed that, with increasing carbonization temperature, the La, Lc, and Lc/d(002 of CBCFs increased gradually, whereas the degree of disorder R decreased. The –OH, –CH2–, –O–C– and phenyl group characteristic absorption peaks of CBCFs reduced gradually. The cross-linked structure of CBCFs was converted into a graphite structure with a six-ring carbon network during carbonization. The surface of CBCFs were mainly comprised of C–C, C–O, and C=O. The tensile strength, carbonization yield and carbon content of CBCFs obtained at 1000 °C were 1015 MPa, 52%, and 95.04%, respectively.

  20. Mechanical properties of anorthite based ceramics prepared from kaolin DD2 and calcite

    Energy Technology Data Exchange (ETDEWEB)

    Harabi, A.; Zaiou, S.; Guechi, A.; Foughali, L.; Harabi, E.; Karboua, N.-E.; Zouai, S.; Mezahi, F.-Z.; Guerfa, F., E-mail: harabi52@gmail.com, E-mail: Zaiou_21@yahoo.fr, E-mail: guechia@yahoo.fr, E-mail: semouni84@gmail.com, E-mail: kanour17@yahoo.fr, E-mail: foughali_lazhar@yahoo.fr, E-mail: zouaisouheila@yahoo.fr, E-mail: mezahif@yahoo.fr [Ceramics Lab., Faculty of Exact Science, Physics Department, Mentouri University of Constantine (Algeria)

    2017-07-15

    Good quality ceramics costs a lot that has limited their use in developing countries. This work was devoted to prepare low-cost and good quality anorthite based ceramics. The proposed composition was 80 wt% kaolin (DD2 type) and 20 wt% calcium oxide (CaO). The choice of these raw materials was dictated by their natural abundance coupled with a modified milling system, as another interesting advantage. Previous studies have shown that a simple vibratory multidirectional milling system using bimodal distribution of highly resistant ceramic milling elements has been successfully applied for obtaining fine powders. The influence of the relatively lower sintering temperature, ranging from 800 to 1100 °C, on the porosity and the average pore size (APS) have been investigated. The APS and the porosity values of samples sintered at 950 °C were about 1 μm and 4%, respectively. The best Vickers microhardness and 3-point bending strength values for these sintered samples, using this proposed milling system, were 7.1 GPa and 203 MPa, respectively. Finally, the crystalline phase evolution during heat treatment was investigated by X-ray diffraction, Fourier transform infrared spectroscopy and scanning electron microscopy techniques. (author)

  1. Polish Academy of Sciences Great Dictionary of Polish [Wielki słownik języka polskiego PAN

    Directory of Open Access Journals (Sweden)

    Piotr Žmigrodzki

    2014-12-01

    Full Text Available The paper describes a lexicographical project involving the development of the newest general dictionary of the Polish language: the Polish Academy of Sciences Great Dictionary of Polish [Wielki słownik języka polskiego PAN]. The project is coordinated by the Institute of Polish Language at the Polish Academy of Sciences and carried out in collaboration with linguists and lexicographers from several other Polish academic centres. The paper offers a brief description of the genesis of the project and the scope of information included in the dictionary, the organisation of work, the life of the dictionary on the Web as well as the plans for the future.

  2. The preparation and mechanical properties of carbon–carbon/lithium–aluminum–silicate composite joints

    International Nuclear Information System (INIS)

    Li, Ke-zhi; Wang, Jie; Ren, Xiao-bin; Li, He-jun; Li, Wei; Li, Zhao-qian

    2013-01-01

    Highlights: ► First study to join carbon cloth laminated C–C composites to LAS glass–ceramics. ► First study on the flexural property of C–C/LAS joints at different temperatures. ► The joint flexural strength at 800 °C can increase 14.1% than at room temperature. ► A quasi-ductile fracture behavior can be found in the C–C/LAS joints. -- Abstract: Silica carbide modified carbon cloth laminated C–C composites have been successfully joined to lithium–aluminum–silicate (LAS) glass–ceramics using magnesium–aluminum–silicate (MAS) glass–ceramics as interlayer by vacuum hot-press technique. The microstructure, mechanical properties and fracture mechanism of C–C/LAS composite joints were investigated. SiC coating modified the wettability between C–C composites and LAS glass–ceramics. Three continuous and homogenous interfaces (i.e. C–C/SiC, SiC/MAS and MAS/LAS) were formed by element interdiffusions and chemical reactions, which lead to a smooth transition from C–C composites to LAS glass–ceramics. The C–C/LAS joints have superior flexural property with a quasi-ductile behavior. The average flexural strength of C–C/LAS joints can be up to 140.26 MPa and 160.02 MPa at 25 °C and 800 °C, respectively. The average shear strength of C–C/LAS joints achieves 21.01 MPa and the joints are apt to fracture along the SiC/MAS interface. The high retention of mechanical properties at 800 °C makes the joints to be potentially used in a broad temperature range as structural components.

  3. Preparation of highly absorbing polymeric hydrogels by radiation processing: mechanical and physical properties

    International Nuclear Information System (INIS)

    Dragusin, M.

    1994-01-01

    Some highly absorbing polymeric hydrogels such as acrylic polymers were produced by radiation processing with gamma sources Co-60 of 10,000 Ci, 3 kGy/h and an electron beam accelerator of 3 - 6 MeV, 0.3 - 3 kGy/s. For practical purposes, such as different applications in agriculture, etc, we studied the physical properties of residual monomers by refractometric and polarographic methods and the mechanical properties (gel strength) with devices made in our laboratory. (Author)

  4. Stress 'deafness' in a language with fixed word stress: an ERP study on Polish

    Directory of Open Access Journals (Sweden)

    Ulrike eDomahs

    2012-11-01

    Full Text Available The aim of the present contribution was to examine the factors influencing the prosodic processing in a language with predictable word stress. For Polish, a language with fixed penultimate stress but several well-defined exceptions, difficulties in the processing and representation of prosodic information have been reported (e.g., Peperkamp & Dupoux, 2002. The present study utilized event-related potentials (ERPs to investigate the factors influencing prosodic processing in Polish. These factors are i the predictability of stress and ii the prosodic structure in terms of metrical feet. Polish native speakers were presented with correctly and incorrectly stressed Polish words and instructed to judge the correctness of the perceived stress patterns. For each stress violation an early negativity was found which was interpreted as reflection of an error-detection mechanism, and in addition exceptional stress patterns (= antepenultimate stress and post-lexical (= initial stress evoked a task-related positivity effect (P300 whose amplitude and latency is correlated with the degree of anomaly and deviation from an expectation. Violations involving the default (= penultimate stress in contrast did not produce such an effect. This asymmetrical result is interpreted to reflect that Polish native speakers are less sensitive to the default pattern than to the exceptional or post-lexical patterns. Behavioral results are orthogonal to the electrophysiological results showing that Polish speakers had difficulties to reject any kind of stress violation. Thus, on a meta-linguistic level Polish speakers appeared to be stress-‘deaf’ for any kind of stress manipulation, whereas the neural reactions differentiate between the default and lexicalized patterns.

  5. Nd:YOV4 laser polishing on WC-Co HVOF coating

    Science.gov (United States)

    Giorleo, L.; Ceretti, E.; Montesano, L.; La Vecchia, G. M.

    2017-10-01

    WC/Co coatings are widely applied to different types of components due to their extraordinary performance properties including high hardness and wear properties. In industrial applications High Velocity Oxy-Fuel (HVOF) technique is extensively used to deposit hard metal coatings. The main advantage of HVOF compared to other thermal spray techniques is the ability to accelerate the melted powder particles of the feedstock material at a relatively high velocity, leading to obtain good adhesion and low porosity level. However, despite the mentioned benefits, the surface finish quality of WC-Co HVOF coatings results to be poor (Ra higher than 5 µm) thus a mechanical polishing process is often needed. The main problem is that the high hardness of coating leads the polishing process expensive in terms of time and tool wear; moreover polishing becomes difficult and not always possible in case of limited accessibility of a part, micro dimensions or undercuts. Nowadays a different technique available to improve surface roughness is the laser polishing process. The polishing principle is based on focused radiation of a laser beam that melts a microscopic layer of surface material. Compared to conventional polishing process (as grinding) it ensures the possibility of avoiding tool wear, less pollution (no abrasive or liquids), no debris, less machining time and coupled with a galvo system it results to be more suitable in case of 3D complex workpieces. In this paper laser polishing process executed with a Nd:YOV4 Laser was investigated: the effect of different process parameters as initial coating morphology, laser scan speed and loop cycles were tested. Results were compared by a statistical approach in terms of average roughness along with a morphological analysis carried out by Scanning Electron Microscope (SEM) investigation coupled with EDS spectra.

  6. Recovery of rare earths from used polishes by chemical vapor transport process

    International Nuclear Information System (INIS)

    Ozaki, T.; Machida, K.; Adachi, G.

    1998-01-01

    Full text: Rare earth oxide polishes are widely used in the glass industry because of its mechanical and chemical polishing action. The Japanese glass industry use 2000 tons per year of the polishes, and a large portion of them are thrown away after their polishing lifetime. A dry recovery processes for rare earths from the used polishes have been investigated by using a chemical vapor transport method via the formation of vapor complexes RAl n Cl 3+3n (R = rare earths). A flow type reactor with various temperature gradients was employed for the process. The used polishes were mixed with active carbon, and chlorinated with N 2 + Cl 2 mixture at 1273 K. Aluminium oxide were also chlorinated at lower temperature and the resulting AlCl 3 were introduced to the reactor. The rare earth chlorides and AlCl 3 were converted to the vapor complexes. These were driven along the temperature gradient, decomposed according to the reverse reaction, and regenerated RCl 3 . About 90 % of the used polish were chlorinated after 2 hours. Rare earth chlorides, AlCl 3 , and FeCl 3 were fully transported after 82 hours. The rare earth chlorides were mainly condensed over the temperature range 1263-903 K. On the other hand, AlCl 3 and FeCl 3 were deposited at the temperature range below 413 K. CaCl 2 and SrCl 2 were hardly transported and remained in the residue. When the temperature gradient with the smaller slope was used, mutual separation efficiencies among the rare earths was improved. The highest CeCl 3 purity of 80% was obtained in the process

  7. Preparative conditions and vibrational study of HUP : phase transition and conductivity mechanisms

    International Nuclear Information System (INIS)

    Thi, M.P.; Novak, A.; Colomban, Ph.

    1985-01-01

    Among solid protonic conductors HUP (H 3 OUO 2 PO 4 .3 H 2 O) exhibits very high conducting properties. Uranyl/phosphate hydrates belonging to the HUP family (HUP ; UO 2 (H 2 PO 4 ) 2 .3 H 2 O ; (U= 2 ) 3 (PO 4 ) 2 .4 H 2 O ; (UO O 2 )sub(1.43)PO 4 Hsub(0.14) 2-3.5 H 2 O) have been synthesized in different forms (crystals, powders, films, ...) and characterized by various methods: chemical analysis, DTA, TGA, SEM, X-Ray diffraction, IR and Raman spectroscopy. Morphological studies reveal the presence of various particulat es, from ultrafine powders ( 2 O washing of HUP. Infrared and Raman spectra of polycrystalline H 3 OUO 2 PO 4 .3 H 2 O (HUP) have been investigated at various temperatures between 50 K and 300 K. The most temperature-sensitive bands correspond to PO 4 and H 2 O librations; U-OPO 3 stretching and OH stretching vibrations indicate four different phases of HUP and allow to propose a phasetransition mechanism from a bidimensionnal, quasi-liquid state of a protonated species in the room-temperature phase to a fully ordered crystal below 130 K. The protonic conductivity mechanism of room- and low-temperature phases is discussed. (author)

  8. Preparations and mechanism of hydrolysis of ([8]annulene)actinide compounds

    International Nuclear Information System (INIS)

    Moore, R.M. Jr.

    1985-07-01

    The mechanism of hydrolysis for bis[8]annulene actinide and lanthanide complexes has been studied in detail. The uranium complex, uranocene, decomposes with good pseudo-first order kinetics (in uranocene) in 1 M degassed solutions of H 2 O in THF. Decomposition of a series of aryl-substituted uranocenes demonstrates that the hydrolysis rate is dependent on the electronic nature of the substituent (Hammett rho value = 2.1, r 2 = 0.999), with electron-withdrawing groups increasing the rate. When D 2 O is substituted for H 2 O, kinetic isotope effects of 8 to 14 are found for a variety of substituted uranocenes. These results suggest a pre-equilibrium involving approach of a water molecule to the central metal, followed by rate determining proton transfer to the eight membered ring and rapid decomposition to products. Each of the four protonations of the complex has a significant isotope effect. The product ratio of cyclooctatriene isomers formed in the hydrolysis varies, depending on the central metal of the complex. However, the general mechanism of hydrolysis, established for uranocene, can be extended to the hydrolysis and alcoholysis of all the [8]annulene complexes of the lanthanides and actinides

  9. Preparation of reduced graphene oxide/gelatin composite films with reinforced mechanical strength

    International Nuclear Information System (INIS)

    Wang, Wenchao; Wang, Zhipeng; Liu, Yu; Li, Nan; Wang, Wei; Gao, Jianping

    2012-01-01

    Highlights: ► We used and compared different proportion of gelatin and chitosan as reducing agents. ► The mechanical properties of the films are investigated, especially the wet films. ► The cell toxicity of the composite films as biomaterial is carried out. ► The water absorption capabilities of the composite films also studied. -- Abstract: Graphene oxide (GO) was reduced by chitosan/gelatin solution and added to gelatin (Gel) to fabricate reduced graphene oxide/gelatin (RGO/Gel) films by a solvent-casting method using genipin as cross-linking agent. The structure and properties of the films were characterized by scanning electron microscopy (SEM), X-ray powder diffraction (XRD), thermogravimetric analysis (TGA) and UV–vis spectroscopy. The addition of RGO increased the tensile strength of the RGO/Gel films in both dry and wet states, but decreased their elongation at break. The incorperation of RGO also decreased the swelling ability of the films in water. Cell cultures were carried out in order to test the cytotoxicity of the films. The cells grew and reproduced well on the RGO/Gel films, indicating that the addition of RGO has no negative effect on the compatibility of the gelatin. Therefore, the reduced graphene oxide/gelatin composite is a promising biomaterial with excellent mechanical properties and good cell compatibility.

  10. A novel strategy for preparing mechanically robust ionically cross-linked alginate hydrogels

    International Nuclear Information System (INIS)

    Jejurikar, Aparna; Lawrie, Gwen; Groendahl, Lisbeth; Martin, Darren

    2011-01-01

    The properties of alginate films modified using two cross-linker ions (Ca 2+ and Ba 2+ ), comparing two separate cross-linking techniques (the traditional immersion (IM) method and a new strategy in a pressure-assisted diffusion (PD) method), are evaluated. This was achieved through measuring metal ion content, water uptake and film stability in an ionic solution ([Ca 2+ ] = 2 mM). Characterization of the internal structure and mechanical properties of hydrated films were established by cryogenic scanning electron microscopy and tensile testing, respectively. It was found that gels formed by the PD technique possessed greater stability and did not exhibit any delamination after 21 day immersion as compared to gels formed by the IM technique. The Ba 2+ cross-linked gels possessed significantly higher cross-linking density as reflected in lower water content, a more dense internal structure and higher Young's modulus compared to Ca 2+ cross-linked gels. For the Ca 2+ cross-linked gels, a large improvement in the mechanical properties was observed in gels produced by the PD technique and this was attributed to thicker pore walls observed within the hydrogel structure. In contrast, for the Ba 2+ cross-linked gels, the PD technique resulted in gels that had lower tensile strength and strain energy density and this was attributed to phase separation and larger macropores in this gel.

  11. Mechanical Validation of an MRI Compatible Stereotactic Neurosurgery Robot in Preparation for Pre-Clinical Trials

    Science.gov (United States)

    Nycz, Christopher J; Gondokaryono, Radian; Carvalho, Paulo; Patel, Nirav; Wartenberg, Marek; Pilitsis, Julie G; Fischer, Gregory S

    2018-01-01

    The use of magnetic resonance imaging (MRI) for guiding robotic surgical devices has shown great potential for performing precisely targeted and controlled interventions. To fully realize these benefits, devices must work safely within the tight confines of the MRI bore without negatively impacting image quality. Here we expand on previous work exploring MRI guided robots for neural interventions by presenting the mechanical design and assessment of a device for positioning, orienting, and inserting an interstitial ultrasound-based ablation probe. From our previous work we have added a 2 degree of freedom (DOF) needle driver for use with the aforementioned probe, revised the mechanical design to improve strength and function, and performed an evaluation of the mechanism’s accuracy and effect on MR image quality. The result of this work is a 7-DOF MRI robot capable of positioning a needle tip and orienting it’s axis with accuracy of 1.37 ± 0.06mm and 0.79° ± 0.41°, inserting it along it’s axis with an accuracy of 0.06 ± 0.07mm, and rotating it about it’s axis to an accuracy of 0.77° ± 1.31°. This was accomplished with no significant reduction in SNR caused by the robot’s presence in the MRI bore, ≤ 10.3% reduction in SNR from running the robot’s motors during a scan, and no visible paramagnetic artifacts. PMID:29696097

  12. MEMORANDUM: Application of Best Management Practices to Mechanical Silvicultural Site Preparation Activities for the Establishment of Pine Plantations in the Southeast

    Science.gov (United States)

    Memorandum to the Field, November 28, 1995, clarifying the applicability of forested wetlands best management practices to mechanical silvicultural site preparation activities for the establishment of pine plantations in the Southeast.

  13. Microstructure, mechanical properties and superelasticity of biomedical porous NiTi alloy prepared by microwave sintering.

    Science.gov (United States)

    Xu, J L; Bao, L Z; Liu, A H; Jin, X J; Tong, Y X; Luo, J M; Zhong, Z C; Zheng, Y F

    2015-01-01

    Porous NiTi alloys were prepared by microwave sintering using ammonium hydrogen carbonate (NH4HCO3) as the space holder agent to adjust the porosity in the range of 22-62%. The effects of porosities on the microstructure, hardness, compressive strength, bending strength, elastic modulus, phase transformation temperature and superelasticity of the porous NiTi alloys were investigated. The results showed that the porosities and average pore sizes of the porous NiTi alloys increased with increasing the contents of NH4HCO3. The porous NiTi alloys consisted of nearly single NiTi phase, with a very small amount of two secondary phases (Ni3Ti, NiTi2) when the porosities are lower than 50%. The amount of Ni3Ti and NiTi2 phases increased with further increasing of the porosity proportion. The porosities had few effects on the phase transformation temperatures of the porous NiTi alloys. By increasing the porosities, all of the hardness, compressive strength, elastic modulus, bending strength and superelasticity of the porous NiTi alloys decreased. However, the compressive strength and bending strength were higher or close to those of natural bone and the elastic modulus was close to the natural bone. The superelastic recovery strain of the trained porous NiTi alloys could reach between 3.1 and 4.7% at the pre-strain of 5%, even if the porosity was up to 62%. Moreover, partial shape memory effect was observed for all porosity levels under the experiment conditions. Therefore, the microwave sintered porous NiTi alloys could be a promising candidate for bone implant. Copyright © 2014 Elsevier B.V. All rights reserved.

  14. Effects of air-polishing powders on color stability of composite resins.

    Science.gov (United States)

    Güler, Ahmet Umut; Duran, Ibrahim; Yücel, Ali Çağin; Ozkan, Pelin

    2011-10-01

    The purpose of this study was to investigate the effect of different air-polishing powders on the color stability of different types of composite resin restorative materials. Thirty cylindrical specimens (15×2 mm) were prepared for each of 7 composite resin restorative materials. All specimens were polished with a series of aluminum oxide polishing discs (Sof-Lex). The prepared specimens of each composite resin were randomly divided into 3 groups of 10 specimens each, for control (Group-C) and two air-powder applications (Group-CP: Cavitron Prophy-Jet; Group-PS: Sirona ProSmile prophylaxis powder). A standard air-polishing unit (ProSmile Handly) was used. All specimens were air-powdered for 10 s at 4-bar pressure. The distance of the spray nosel from the specimens was approximately 10 mm and angulation of the nosel was 90°. Specimens were stored in 100 mL of coffee (Nescafe Classic) for 24 h at 37°C. Color measurement of all specimens was recorded before and after exposure to staining agent with a colorimeter (Minolta CR-300). Color differences (∆E*) between the 2 color measurements (baseline and after 24 h storage) were calculated. The data were analyzed with a 2-way ANOVA test, and mean values were compared by the Tukey HSD test (p.05) and these groups demonstrated the highest ∆E* values. For Filtek Silorane and IntenS, the highest ∆E* values were observed in Group-PS. The lowest ∆E* values for all composite resin groups were observed in Group-C. When comparing the 7 composite resin restorative materials, Aelite Aesthetic Enemal demonstrated significantly less ∆E* values than the other composite resins tested. The highest ∆E* values were observed in Quixfil. Except for Quixfil, all control groups of composite resins that were polished Sof-Lex exhibited clinically acceptable ∆E values (<3.7). Air-polishing applications increased the color change for all composite resin restorative materials tested. Composite restorations may require re-polishing

  15. Effects of air-polishing powders on color stability of composite resins

    Directory of Open Access Journals (Sweden)

    Ahmet Umut Güler

    2011-10-01

    Full Text Available OBJECTIVES: The purpose of this study was to investigate the effect of different air-polishing powders on the color stability of different types of composite resin restorative materials. MATERIAL AND METHODS: Thirty cylindrical specimens (15×2 mm were prepared for each of 7 composite resin restorative materials. All specimens were polished with a series of aluminum oxide polishing discs (Sof-Lex. The prepared specimens of each composite resin were randomly divided into 3 groups of 10 specimens each, for control (Group-C and two air-powder applications (Group-CP: Cavitron Prophy-Jet; Group-PS: Sirona ProSmile prophylaxis powder. A standard air-polishing unit (ProSmile Handly was used. All specimens were air-powdered for 10 s at 4-bar pressure. The distance of the spray nosel from the specimens was approximately 10 mm and angulation of the nosel was 90°. Specimens were stored in 100 mL of coffee (Nescafe Classic for 24 h at 37°C. Color measurement of all specimens was recorded before and after exposure to staining agent with a colorimeter (Minolta CR-300. Color differences (∆E* between the 2 color measurements (baseline and after 24 h storage were calculated. The data were analyzed with a 2-way ANOVA test, and mean values were compared by the Tukey HSD test (p.05 and these groups demonstrated the highest ∆E* values. For Filtek Silorane and IntenS, the highest ∆E* values were observed in Group-PS. The lowest ∆E* values for all composite resin groups were observed in Group-C. When comparing the 7 composite resin restorative materials, Aelite Aesthetic Enemal demonstrated significantly less ∆E* values than the other composite resins tested. The highest ∆E* values were observed in Quixfil. CONCLUSION: Except for Quixfil, all control groups of composite resins that were polished Sof-Lex exhibited clinically acceptable ∆E values (<3.7. Air-polishing applications increased the color change for all composite resin restorative materials

  16. Determination of Microstructural Parameters of Nanocrystalline Hydroxyapatite Prepared by Mechanical Alloying Method

    Science.gov (United States)

    Joughehdoust, Sedigheh; Manafi, Sahebali

    2011-12-01

    Hydroxyapatite [HA, Ca10(PO4)6(OH)2] is chemically similar to the mineral component of bones and hard tissues. HA can support bone ingrowth and osseointegration when used in orthopaedic, dental and maxillofacial applications. In this research, HA nanostructure was synthesized by mechanical alloying method. Phase development, particle size and morphology of HA were investigated by X-ray diffraction (XRD) pattern, zetasizer instrument, scanning electron microscopy (SEM), respectively. XRD pattern has been used to determination of the microstructural parameters (crystallite size, lattice parameters and crystallinity percent) by Williamson-Hall equation, Nelson-Riley method and calculating the areas under the peaks, respectively. The crystallite size and particle size of HA powders were in nanometric scales. SEM images showed that some parts of HA particles have agglomerates. The ratio of lattice parameters of synthetic hydroxyapatite (c/a = 0.73) was determined in this study is the same as natural hydroxyapatite structure.

  17. Structural instability and photoacoustic study of AlSb prepared by mechanical alloying

    Energy Technology Data Exchange (ETDEWEB)

    Triches, D.M.; Souza, S.M.; Poffo, C.M. [Departamento de Engenharia Mecanica, Universidade Federal de Santa Catarina, 88040-900 Florianopolis, SC (Brazil); Lima, J.C. de, E-mail: fsc1jcd@fsc.ufsc.b [Departamento de Fisica, Universidade Federal de Santa Catarina, 88040-900 Florianopolis, SC (Brazil); Grandi, T.A. [Departamento de Fisica, Universidade Federal de Santa Catarina, 88040-900 Florianopolis, SC (Brazil); Biasi, R.S. de [Secao de Engenharia Mecanica e de Materiais, Instituto Militar de Engenharia, 22290-270 Rio de Janeiro, RJ (Brazil)

    2010-09-03

    High-purity elemental Al and Sb powders were blended with equiatomic composition and submitted to mechanical alloying. For all milling times, the milled powders showed a mixture of AlSb and elemental Sb. The largest amount of AlSb was reached for milling times between 7 and 10 h. For milling times larger than 10 h, decomposition of AlSb was observed. The volume fractions of the crystalline and interfacial components were estimated using the X-ray diffraction pattern of a sample milled for 10 h. Photoacoustic absorption spectroscopy (PAS) was used to determine the thermal diffusivity and other heat transport parameters in the same sample. A combination of XRD and PAS data was used to estimate the thermal diffusivity of the interfacial component, which has a significant contribution to the thermal diffusivity of the sample.

  18. Structural instability and photoacoustic study of AlSb prepared by mechanical alloying

    International Nuclear Information System (INIS)

    Triches, D.M.; Souza, S.M.; Poffo, C.M.; Lima, J.C. de; Grandi, T.A.; Biasi, R.S. de

    2010-01-01

    High-purity elemental Al and Sb powders were blended with equiatomic composition and submitted to mechanical alloying. For all milling times, the milled powders showed a mixture of AlSb and elemental Sb. The largest amount of AlSb was reached for milling times between 7 and 10 h. For milling times larger than 10 h, decomposition of AlSb was observed. The volume fractions of the crystalline and interfacial components were estimated using the X-ray diffraction pattern of a sample milled for 10 h. Photoacoustic absorption spectroscopy (PAS) was used to determine the thermal diffusivity and other heat transport parameters in the same sample. A combination of XRD and PAS data was used to estimate the thermal diffusivity of the interfacial component, which has a significant contribution to the thermal diffusivity of the sample.

  19. Influencing Mechanism of Electrochemical Treatment on Preparation of CNTs-grafted on Carbon Fibers

    Directory of Open Access Journals (Sweden)

    SONG Lei

    2017-11-01

    Full Text Available Based on electrochemical anodic oxidation, an innovative technique was developed to efficiently obtain the uniform catalyst coating on continuous carbon fibers. Through systematic investigation on the effect of electrochemical modified strength on the physical and chemical characteristics of carbon fiber surface, catalyst particles and the morphology of CNTs-grafted carbon fibers, tensile strength of multi-scale reinforcement and the interlaminar shear strength of its reinforced composites, the electrochemical modification process on carbon fibre surface was optimized. The results show that the morphology and distribution of catalyst particles not only affect the morphology of CNTs deposited on the surface of carbon fibres,but also affect the mechanical properties of multi-scale reinforcement and its reinforced composites of CNTs-grafted carbon fibers.

  20. Mechanical Design and Manufacturing Preparation of Loading Unloading Irradiation Facility in Reflector Irradiation Position

    International Nuclear Information System (INIS)

    Hasibuan, Djaruddin

    2004-01-01

    Base on planning to increase of the irradiation service quality in Multi purpose Reactor-GAS, the mechanical design and manufacturing of the (n,γ) irradiation facility has been done. The designed of (n,γ) irradiation facility is a new facility in Multi purpose Reactor-GAS. The design doing by design of stringer, guide bar and hanger. By the design installation, the continuous irradiation service of non fission reaction will be easy to be done without reactor shut down. The design of the facility needs 3 pieces Al pipe by 36 x 1.5 mm, a peace of Al round bar by 80 mm diameter and a piece of Al plate by 20 x 60 x 0.2 mm for the stringer and guide bar manufacturing. By the building of non fission irradiation facility in the reflector irradiation position, will make the irradiation service to be increased. (author)

  1. Preparation and Investigation of Mechanical Properties and Optical Clarity of Polyvinylbutyral Film

    Directory of Open Access Journals (Sweden)

    Morteza Hajian

    2013-01-01

    Full Text Available Polyvinyl butyral (PVB was synthesized by condensation reaction of polyvinyl alcohol (PVA with butanal in aqueous medium containing an effective emulsifier and an inorganic acid as catalyst. The product was characterized by, IR, TG and DTG techniques. Percentage of vinyl alcohol groups in the PVB was determined by a chemical method according to a standard method. Some clear and soft film samples containing the PVB and some high boiling point plasticizers were made by hot press. For this purpose plasticizers such as bis(2-ethylhexylphthalate (DOP and bis(2-ethylhexyl terephthalate (DOTP were purchased and the triethylene glycol bis(2-ethylhexanoate (TEGB was synthesized. The film samples containing 30 percent mixture of triethylene glycol bis(2-ethylhexanoate and bis (2-ethylhexylphthalate with ratio 65/35 showed some improved mechanical and optical properties.

  2. Preparation and mechanical properties of carbon nanotube-silicon nitride nano-ceramic matrix composites

    Science.gov (United States)

    Tian, C. Y.; Jiang, H.

    2018-01-01

    Carbon nanotube-silicon nitride nano-ceramic matrix composites were fabricated by hot-pressing nano-sized Si3N4 powders and carbon nanotubes. The effect of CNTs on the mechanical properties of silicon nitride was researched. The phase compositions and the microstructure characteristics of the samples as well as the distribution of carbon nanotube in the silicon nitride ceramic were analyzed by X-ray diffraction and scanning electron microscope. The results show that the microstructure of composites consists mainly of α-Si3N4, β-Si3N4, Si2N2O and carbon natubes. The addition of proper amount of carbon nanotubes can improve the fracture toughness and the flexural strength, and the optimal amount of carbon nanotube are both 3wt.%. However the Vickers hardness values decrease with the increase of carbon nanotubes content.

  3. Preparation of Artificial Skin that Mimics Human Skin Surface and Mechanical Properties.

    Science.gov (United States)

    Shimizu, Rana; Nonomura, Yoshimune

    2018-01-01

    We have developed an artificial skin that mimics the morphological and mechanical properties of human skin. The artificial skin comprises a polyurethane block possessing a microscopically rough surface. We evaluated the tactile sensations when skin-care cream was applied to the artificial skin. Many subjects perceived smooth, moist, and soft feels during the application process. Cluster analysis showed that these characteristic tactile feels are similar to those when skin-care cream is applied to real human skin. Contact angle analysis showed that an oil droplet spread smoothly on the artificial skin surface, which occurred because there were many grooves several hundred micrometers in width on the skin surface. In addition, when the skin-care cream was applied, the change in frictional force during the dynamic friction process increased. These wetting and frictional properties are important factors controlling the similarity of artificial skin to real human skin.

  4. MECHANICAL PROPERTIES OF CR-DLC LAYERS PREPARED BY HYBRID LASER TECHNOLOGY

    Directory of Open Access Journals (Sweden)

    Petr Písařík

    2017-06-01

    Full Text Available Diamond like carbon (DLC layers have excellent biological properties for use in medicine for coating implants, but poor adhesion to biomedical alloys. The adhesion can be improved by doping the DLC layer by chromium, as described in this article. Chromium doped diamond like carbon layers (Cr‑DLC were deposited by hybrid deposition system using KrF excimer laser and magnetron sputtering. Carbon and chromium contents were determined by wavelength dispersive X-ray spectroscopy. Mechanical properties were studied by nanoindentation. Hardness and reduced Young's modulus reached 31.2 GPa and 271.5 GPa, respectively. Films adhesion was determined by scratch test and reached 19 N for titanium substrates. Good adhesion to biomedical alloys and high DLC hardness will help to progress in the field of implantology.

  5. Boron nitride-MWCNT/epoxy hybrid nanocomposites: Preparation and mechanical properties

    International Nuclear Information System (INIS)

    Ulus, Hasan; Üstün, Tugay; Eskizeybek, Volkan; Şahin, Ömer Sinan; Avcı, Ahmet; Ekrem, Mürsel

    2014-01-01

    Highlights: • We studied the effects of BN nanoplatelets on tensile strength and elasticity modulus for polymer composites. • We investigated the synergetic effects of BN nanoplatelets and MWCNTs on tensile strength and elasticity modulus for polymer composites. • Fracture surfaces were examined by SEM analysis. - Abstract: In this study, production and mechanical properties of hybrid nanocomposites have been investigated. Hybrid nanocomposites are consisting of boron nitride nanoplatelets (BN) and multiwall carbon nanotubes (MWCNT) embedded in epoxy resin. The BN and MWCNT were mixed to epoxy resin in different weight fractions and mixtures were utilized for tensile test specimen production. The synthesized BN and produced hybrid nanocomposites were characterized by SEM, TEM, XRD, FT-IR and TGA analyses. The elasticity modulus and tensile strength values were obtained via tensile tests. The fracture morphologies were investigated after tensile test by means of scanning electron microscopy

  6. Magnetic field sensor based on double-sided polished fibre-Bragg gratings

    International Nuclear Information System (INIS)

    Tien, Chuen-Lin; Hwang, Chang-Chou; Liu, Wen-Feng; Chen, Hong-Wei

    2009-01-01

    A new magnetic field sensor based on double-sided polished fibre-Bragg gratings (FBGs) coated with an iron thin film for measuring magnetic flux density was experimentally demonstrated with the sensitivity of 25.6 nm T −1 . The sensing mechanism is based on the Bragg wavelength shift as the magnetic field is measured by the proposed sensing head. Results of this study present the intensity of the reflected optical signal as a function of the applied strain on the FBG. This paper shows that an improved method for sensing the wavelength shift with changes in external magnetic field is developed by use of the double-sided polished FBGs

  7. A Study of Polishing Feature of Ultrasonic-Assisted Vibration Method in Bamboo Charcoal

    Directory of Open Access Journals (Sweden)

    Hsin-Min Lee

    2017-01-01

    Full Text Available Focusing on the feature of porosity in bamboo charcoal, this study applies the ultrasonic-assisted vibration method to perform surface polishing of the silicon wafer workpiece. The self-developed bamboo charcoal polishing spindle and ultrasonic- assisted vibration mechanism are attached to a single lapping machine. In the machining process, ultrasonic vibration enables the diamond slurry to smoothly pass through the microscopic holes of bamboo charcoal; the end of the bamboo charcoalis able to continue machining on the surface of the workpiece through the grasping force which exists in the microscopic holes. Under the polishing and machining parameters of ultrasonic-assisted vibration, with a diamond slurry concentration of 0.3%, the experimental results show a polishing time of 20 min, a loading of 25 N on the workpiece surface, a spindle speed of 1200 rpm, a vibration frequency of 30 kHz and the original surface roughness value of Ra 0.252 μm equals that of a mirror-like surface at Ra 0.017 μm. These research results prove that by using bamboo charcoal and ultrasonic-assisted vibration for polishing, a very good improvement can be achieved on the workpiece surface.

  8. Precision machining and polishing of scintillating crystals for large calorimeters and hodoscopes

    International Nuclear Information System (INIS)

    Wuest, C.R.; Fuchs, B.A.; Holdener, F.R.; Heck, J.L. Jr.

    1994-04-01

    New machining and polishing techniques have been developed for large scintillating crystal arrays such as the Barium Fluoride Electromagnetic Calorimeter for the GEM Detector at SSCL, the Crystal Clear Collaboration's cerium fluoride or lead tungstenate calorimeter at the proposed LHC and CERN, the PHENIX Detector at RHIC (barium fluoride), and the cesium iodide Calorimeter for the BaBar Detector at PEP-2 B Factory at SLAC. The machining and polishing methods to be presented in this paper provide crystalline surfaces without sub-surface damage or deformation as verified by Rutherford Back-scattering (RBS) analysis. Surface roughness of about 10--20 angstroms and sub-micron mechanical tolerances have been demonstrated on large barium fluoride crystal samples. Mass production techniques have also been developed for machining the proper angled surfaces and polishing up to five 50 cm long crystals at one time. These techniques utilize kinematic mount technology developed at LLNL to allow precision machining and polishing of complex surfaces. They will present this technology along with detailed surface studies of barium fluoride and cerium fluoride crystals polished with this technique

  9. Wastewater polishing by a channelized macrophyte-dominated wetland and anaerobic digestion of the harvested phytomass

    Science.gov (United States)

    : Constructed wetlands (CW) offer a mechanism to meet regulatory standards for wastewater treatment while minimizing energy inputs. To optimize CW wastewater polishing activities and investigate integration of CW with energy production from anaerobic digestion we constructed a pair of three-tier ch...

  10. Immigrant families in historical perspective: the experiences of Polish pioneers in Winnipeg, 1896-1919

    OpenAIRE

    ŁUKASZ ALBAŃSKI

    2017-01-01

    This paper focuses on an early Polish family life in Winnipeg. The family often served as a mechanism to reduce a sense of dislocation and to facilitate immigrants' adaptation. The family was also the primary economic unit. The family relations were affected by gender. Both immigrant men and women found themselves reconsidering traditional roles. Somehow immigration tested their family roles in newways.

  11. Structural and mechanical properties of ZrSiN thin films prepared by reactive magnetron sputtering

    International Nuclear Information System (INIS)

    Freitas, F.G.R.; Conceicao, A.G.S.; Vitoria, E.R.; Carvalho, R.G.; Tentardini, E.K.; Hübler, R.; Soares, G.

    2014-01-01

    Zirconium silicon nitride (ZrSiN) thin films were deposited by reactive magnetron sputtering in order to verify the silicon influence on coating morphology and mechanical properties. The Si/(Zr+Si) ratio was adjusted between 0 to 14.5% just modifying the power applied on the silicon target. Only peaks associated to ZrN crystalline structure were observed in XRD analysis, since Si_3N_4 phase was amorphous. All samples have (111) preferred orientation, but there is a peak intensity reduction and a broadening increase for the sample with the highest Si/(Zr+Si) ratio (14.5%), demonstrating a considerable loss of crystallinity or grain size reduction (about 8 nm calculated by Scherrer). It was also observed that the texture coefficient for (200) increases with silicon addition. Chemical composition and thickness of the coatings were determined by RBS analysis. No significant changes in nano hardness with increasing Si content were found. The thin film morphology observed by SEM presents columnar and non columnar characteristics. The set of results suggests that Si addition is restricting the columnar growth of ZrN thin films. This conclusion is justified by the fact that Si contributes to increase the ZrN grains nucleation during the sputtering process. (author)

  12. Electrocatalysts with platinum, cobalt and nickel preparations by mechanical alloyed and CVD for the reaction of oxygen reduction

    International Nuclear Information System (INIS)

    Garcia C, M. A.

    2008-01-01

    In this research, the molecular oxygen reduction reaction (ORR) was investigated on electrocatalysts of Co, Ni, Pt and their alloys CoNi, PtCo, PtNi and PtCoNi by using H 2 SO 4 0.5 and KOH 0.5 M solutions as electrolytes. The electrocatalysts were synthesized by Mechanical Alloying (MA) and Chemical Vapor Deposition (CVD) processes. For MA, metallic powders were processed during 20 h of milling in a high energy SPEX 8000 mill. For CVD, a hot-wall reactor was utilized and Co, Ni and Pt acetilactetonates were used as precursors. Films were deposited at a total pressure of 1 torr and temperatures of 400-450 C. Electrocatalysts were characterized by X-Ray Diffraction (XRD). Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM) and Energy Dispersive X-Ray Spectroscopy (EDS). Electrocatalysts prepared by mechanical alloying showed a homogeneously dispersed agglomeration of particles with nano metric size. Electrocatalysts obtained by CVD showed, in some cases, non uniform films, with particles of nano metric size, as well. The electrocatalytic performance was evaluated by using the Rotating Disk Electrode technique (RDE). Electrocatalysts prepared by MA showed higher activity than those obtained by CVD. All electrocatalysts were evaluated in alkaline media. Only electrocatalysts containing Pt were evaluated in acid media, because those materials with Co, Ni and their alloys showed instability in acidic media. Most electrocatalysts followed a mechanism for the ORR producing a certain proportion of H 2 O 2 . All electrocatalysts, exhibited a fair or good electrocatalytic activity in comparison with other similar reported materials. It was found that MA and CVD are appropriate processes to prepare electrocatalysts for the ORR with particles of nano metric size and performing with an acceptable catalytic activity. PtCoNi 70-23-7% by MA and PtCoNi-CVD electrocatalysts showed the highest activity in alkaline media, while in acidic electrolyte PtCoNi 70

  13. Preparation and applications of mechanically exfoliated single-layer and multilayer MoS₂ and WSe₂ nanosheets.

    Science.gov (United States)

    Li, Hai; Wu, Jumiati; Yin, Zongyou; Zhang, Hua

    2014-04-15

    Although great progress has been achieved in the study of graphene, the small current ON/OFF ratio in graphene-based field-effect transistors (FETs) limits its application in the fields of conventional transistors or logic circuits for low-power electronic switching. Recently, layered transition metal dichalcogenide (TMD) materials, especially MoS2, have attracted increasing attention. In contrast to its bulk material with an indirect band gap, a single-layer (1L) MoS2 nanosheet is a semiconductor with a direct band gap of ~1.8 eV, which makes it a promising candidate for optoelectronic applications due to the enhancement of photoluminescence and high current ON/OFF ratio. Compared with TMD nanosheets prepared by chemical vapor deposition and liquid exfoliation, mechanically exfoliated ones possess pristine, clean, and high-quality structures, which are suitable for the fundamental study and potential applications based on their intrinsic thickness-dependent properties. In this Account, we summarize our recent research on the preparation, characterization, and applications of 1L and multilayer MoS2 and WSe2 nanosheets produced by mechanical exfoliation. During the preparation of nanosheets, we proposed a simple optical identification method to distinguish 1L and multilayer MoS2 and WSe2 nanosheets on a Si substrate coated with 90 and 300 nm SiO2. In addition, we used Raman spectroscopy to characterize mechanically exfoliated 1L and multilayer WSe2 nanosheets. For the first time, a new Raman peak at 308 cm(-1) was observed in the spectra of WSe2 nanosheets except for the 1L WSe2 nanosheet. Importantly, we found that the 1L WSe2 nanosheet is very sensitive to the laser power during characterization. The high power laser-induced local oxidation of WSe2 nanosheets and single crystals was monitored by Raman spectroscopy and atomic force microscopy (AFM). Hexagonal and monoclinic structured WO3 thin films were obtained from the local oxidization of single- to triple

  14. 21 CFR 872.6030 - Oral cavity abrasive polishing agent.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Oral cavity abrasive polishing agent. 872.6030... (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Miscellaneous Devices § 872.6030 Oral cavity abrasive polishing agent. (a) Identification. An oral cavity abrasive polishing agent is a device in paste or powder form...

  15. Microbiological flora and nail polish: a brief report.

    Science.gov (United States)

    Rayan, G M; Flournoy, D J; Schlageter, P

    1994-11-01

    Removing nail polish and prosthetic nails from operating room (OR) personnel prior to scrubbing and from patients prior to hand surgery is recommended but not practiced in many hospitals. There is concern that nail polish can act as a vehicle for the transfer of infectious agents. This study was designed to determine the incidence of microbiological flora of nail polish in a clinical setting.

  16. Monitoring of Robot Assisted Polishing through parameters of acoustic emission

    DEFF Research Database (Denmark)

    Lazarev, Ruslan; Top, Søren; Bilberg, Arne

    The polishing process is essential for the surface generation of machine tooling components in advanced manufacturing. While robot assisted polishing is faster and more consistent than manual polishing, it can still consume a significant part of ma- chining time and operator presence time...

  17. Polish Qualitative Sociology: The General Features and Development

    OpenAIRE

    Konecki, Krzysztof Tomasz

    2005-01-01

    The article explores the development of Polish qualitative sociology in Poland by presenting its main intellectual routes and some of the general features of Polish sociology. Romanticism and inductionmethod are crucial elements for the development of this discipline in Poland and contribute to its. unigueness. The role of Florian Znaniecki in creating the Polish qualitative sociology is also underlined. Krzysztof Konecki

  18. Preparation, mechanical properties and in vitro cytocompatibility of multi-walled carbon nanotubes/poly(etheretherketone) nanocomposites.

    Science.gov (United States)

    Cao, Jianfei; Lu, Yue; Chen, Hechun; Zhang, Lifang; Xiong, Chengdong

    2018-03-01

    Desired bone repair material must have excellent biocompatibility and high bioactivity. Moreover, mechanical properties of biomaterial should be equivalent to those of human bones. For developing an alternative biocomposite for load-bearing orthopedic application, combination of bioactive fillers with polymer matrix is a feasible approach. In this study, a series of multi-walled carbon nanotubes (MWCNTs)/poly(etheretherketone) (PEEK) bioactive nanocomposites were prepared by a novel coprecipitation-compounding and injection-molding process. Scanning electron microscope (SEM) images revealed that MWCNTs were adsorbed on the surface of PEEK particles during the coprecipitation-compounding process and dispersed homogeneously in the nanocomposite because the conjugated PEEK polymers stabilized MWCNTs by forming strong π-π stack interactions. The mechanical testing revealed that mechanical performance of PEEK was significantly improved by adding MWCNTs (2-8 wt%) and the experimental values obtained were close to or higher than that of human cortical bone. In addition, incorporation of MWCNTs into PEEK matrix also enhanced the roughness and hydrophilicity of the nanocomposite surface. In vitro cytocompatibility tests demonstrated that the MWCNTs/PEEK nanocomposite was in favor of cell adhesion and proliferation of MC3T3-E1 osteoblast cells, exhibiting excellent cytocompatibility and biocompatibility. Thus, this MWCNTs/PEEK nanocomposite may be used as a promising bone repair material in orthopedic implants application.

  19. In-Situ Preparation of Aramid-Multiwalled CNT Nano-Composites: Morphology, Thermal Mechanical and Electric Properties

    Directory of Open Access Journals (Sweden)

    Jessy Shiju

    2018-05-01

    Full Text Available In this work in-situ polymerization technique has been used to chemically link the functionalized multiwalled carbon nanotubes (CNTs with aramid matrix chains. Phenylene diamine monomers were reacted in the first stage with the carboxylic acid functionalized CNTs and then amidized in-situ using terephthaloyl chloride generating chemically bonded CNTs with the matrix. Various proportions of the CNTs were used to prepare the hybrid materials. The functionalization procedure was studied by Fourier transform infrared (FTIR spectroscopy and composite morphology investigated by scanning electron microscopy (SEM. Thermal mechanical properties of these hybrids, together with those where pristine CNTs with similar loadings were used, are compared using tensile and dynamic mechanical analysis (DMA. The tensile strength and temperature involving α-relaxations on CNT loading increased with CNT loading in both systems, but much higher values, i.e., 267 MPa and 353 °C, respectively, were obtained in the chemically bonded system, which are related to the nature of the interface developed as observed in SE micrographs. The water absorption capacity of the films was significantly reduced from 6.2 to 1.45% in the presence pristine CNTs. The inclusion of pristine CNTs increased the electric conductivity of the aramid films with a minimum threshold value at the loading of 3.5 wt % of CNTs. Such mechanically strong and thermally stable aramid and easily processable composites can be suitable for various applications including high performance films, electromagnetic shielding and radar absorption.

  20. Mechanically robust silver coatings prepared by electroless plating on thermoplastic polyurethane

    Science.gov (United States)

    Vasconcelos, B.; Vediappan, K.; Oliveira, J. C.; Fonseca, C.

    2018-06-01

    A simple and low-cost surface functionalization method is proposed to activate a thermoplastic polyurethane (TPU) for the electroless deposition of a silver coating with excellent adhesion and low resistivity. The TPU surface functionalization was performed in solution and consisted in forming a physical interpenetrating network at the TPU surface, involving TPU and polyvinylpyrrolidone (PVP), a polymer displaying a strong affinity for metals. The presence of PVP on the TPU surface and its stability in aqueous solution were assessed by ATR-FTIR and contact angle measurements as a function of the PVP concentration and treatment time. A modified Tollens solution was used to grow a silver film on the TPU substrate, by using the electroless plating method. Compact silver films with an average thickness of 12.5 μm and a resistivity of 8.57 mΩ·cm were obtained for a 24 h plating time. The adhesion strength of the silver film proved to be higher than 8.5 N/cm. The resistance to fatigue of the silver films was studied by performing series of compression/stretching tests (150 cycles). It was concluded that the films kept low resistance values, although displaying a higher sensitivity to compression than to stretching. Furthermore, the films keep a good conductivity for strains up to 400%. The excellent electrical and mechanical properties of the films make them suitable candidates for the coating of multipin dry bioelectrodes. Owing to the high affinity of many metals for PVP, this activation technique has the potential to be extended to the deposition of other metals and other polymers as well, provided a suitable solvent is used.

  1. ISRU Soil Mechanics Vacuum Facility: Soil Bin Preparation and Simulant Strength Characterization

    Science.gov (United States)

    Kleinhenz, Julie; Wilkinson, Allen

    2012-01-01

    Testing in relevant environments is key to exploration mission hardware development. This is true on both the component level (in early development) and system level (in late development stages). During ISRU missions the hardware will interface with the soil (digging, roving, etc) in a vacuum environment. A relevant test environment will therefore involve a vacuum chamber with a controlled, conditioned simulant bed. However, in earth-based granular media, such as lunar soil simulant, gases trapped within the material pore structures and water adsorbed to all particle surfaces will release when exposed to vacuum. Early vacuum testing has shown that this gas release can occur violently, which loosens and weakens the simulant, altering the consolidation state. The Vacuum Facility #13, a mid-size chamber (3.66m tall, 1.5m inner diameter) at the NASA Glenn Research Center has been modified to create a soil mechanics test facility. A 0.64m deep by 0.914m square metric ton bed of lunar simulant was placed under vacuum using a variety of pumping techniques. Both GRC-3 and LHT-3M simulant types have been used. An electric cone penetrometer was used to measure simulant strength properties at vacuum including: cohesion, friction angle, bulk density and shear modulus. Simulant disruptions, caused by off gassing, affected the strength properties, but could be mitigated by reducing pump rate. No disruptions were observed at pressures below 2.5Torr, regardless of the pump rate. However, slow off gassing of the soil lead to long test times, a full week, to reach 10-5Torr. This work highlights the need for robotic machine-simulant hardware and operations in vacuum to expeditiously perform (sub-)systems tests.

  2. Professional Training of Economists at Polish Universities

    Science.gov (United States)

    Ogienko, Olena

    2016-01-01

    Polish experience in professional training of economists at university has been generalized. Structural, content and procedural peculiarities of the training have been defined. It has been proved that key factors for reforming economic education in Poland are globalization, internationalization, integration, technologization and informatization.…

  3. Knowledge Mobilisation in the Polish Education System

    Science.gov (United States)

    Fazlagic, Jan; Erkol, Arif

    2015-01-01

    Poland has made substantial progress in improving the quality of its education system in recent years. This paper aims to describe the situation of the Polish education system from a knowledge management perspective and, to some extent, through innovation policies in education. The many challenges, this paper argues, can be tackled only through…

  4. Sexual Health of Polish Athletes with Disabilities

    Directory of Open Access Journals (Sweden)

    Ryszard Plinta

    2015-06-01

    Full Text Available The purpose of this study was to determine sexual functioning of Polish athletes with disabilities (including paralympians. The study encompassed 218 people with physical disabilities, aged between 18 and 45 (149 men and 69 women. The entire research population was divided into three groups: Polish paralympians (n = 45, athletes with disabilities (n = 126 and non-athletes with disabilities (n = 47. The quality of sexual life of Polish paralympians was measured by using the Polish version of Female Sexual Function Index and International Index of Erectile Function. Clinically significant erectile dysfunctions were most often diagnosed in non-athletes (83.33% with 50% result of severe erectile dysfunctions, followed by athletes and paralympians with comparable results of 56.98% and 54.17% respectively (p = 0.00388. Statistically significant clinical sexual dysfunctions concerned lubrication, orgasm as well as pain domains, and prevailed among female non-athletes (68.42%, 68.42% and 57.89%. Practising sports at the highest level has a favourable effect on the sexuality of men and women with physical disabilities. Men with physical disabilities manifest more sexual disorders than women, an aspect which should be considered by health-care professionals working with people with disabilities.

  5. Directory of Polish Officials: A Reference Aid

    Science.gov (United States)

    1989-04-01

    Jan 86 Deputy Director Mondalski, Janusz Aug 83 Polish Steamship Company (Polski Zegluga Morska ) (PZM) Director Andruczyk, Mieczyslaw Jan...2<> Polski Kosciol Chrzescijan Baptystow 12° Polski Linie Oceaniczne ’"- Polski Towarzystwo Ekonomiczne ’’° Polski Zegluga Morska 102 Polski

  6. Polish students’ opinion about medicinal cannabis

    Directory of Open Access Journals (Sweden)

    Rafał Mazur

    2017-09-01

    Conclusions: Polish students seem to be ready for introduction into medical marijuana and are aware of its therapeutic potential. The majority is in favor of sales in a controlled manner. The task of researchers should be accurate examination of the effectiveness of specific cannabinoids in the treatment of diseases.

  7. Surface Roughness, Microhardness, and Microleakage of a Silorane-Based Composite Resin after Immediate or Delayed Finishing/Polishing

    Directory of Open Access Journals (Sweden)

    Fernanda Carvalho Rezende Lins

    2016-01-01

    Full Text Available Objective. This study evaluated the effect of immediate or delayed finishing/polishing using different systems on the surface roughness, hardness, and microleakage of a silorane-based composite. Material and Methods. Specimens were made with silorane-based composite (Filtek P90, 3M ESPE and assigned to the treatments: control (light-cured; aluminum oxide discs (Sof-Lex, 3M ESPE; diamond-impregnated silicone tips (Astropol, Ivoclar Vivadent; aluminum oxide-impregnated silicone tips (Enhance, Dentsply. Half of the specimens were finished/polished immediately and the rest after 7 days. Surface roughness (Ra, μm; n=20 and Vickers microhardness (50 g; 45 s; n=10 were measured. Cavities were prepared in bovine incisors and filled with Filtek P90. The fillings received immediate or delayed finishing/polishing (n=10 and were subjected to dye penetration test (0.5% basic fuchsin, 24 h. Data were analyzed by ANOVA and Scheffe, Kruskal-Wallis, and Mann-Whitney tests (p<0.05. Results. The finishing/polishing system significantly influenced roughness and microhardness (p<0.0001. For enamel, microleakage was not affected by the finishing/polishing system (p=0.309. For dentin, Sof-Lex discs and Astropol points promoted greater microleakage than Enhance points (p=0.033. Conclusion. Considering roughness, microhardness, and microleakage together, immediate finishing/polishing of a silorane-based composite using aluminum oxide discs may be recommended.

  8. The corpus-driven revolution in Polish Sign Language: the interview with Dr. Paweł Rutkowski

    Directory of Open Access Journals (Sweden)

    Iztok Kosem

    2018-02-01

    Full Text Available Dr. Paweł Rutkowski is head of the Section for Sign Linguistics at the University of Warsaw. He is a general linguist and a specialist in the field of syntax of natural languages, carrying out research on Polish Sign Language (polski język migowy — PJM. He has been awarded a number of prizes, grants and scholarships by such institutions as the Foundation for Polish Science, Polish Ministry of Science and Higher Education, National Science Centre, Poland, Polish–U.S. Fulbright Commission, Kosciuszko Foundation and DAAD. Dr. Rutkowski leads the team developing the Corpus of Polish Sign Language and the Corpus-based Dictionary of Polish Sign Language, the first dictionary of this language prepared in compliance with modern lexicographical standards. The dictionary is an open-access publication, available freely at the following address: http://www.slownikpjm.uw.edu.pl/en/. This interview took place at eLex 2017, a biennial conference on electronic lexicography, where Dr. Rutkowski was awarded the Adam Kilgarriff Prize and gave a keynote address entitled Sign language as a challenge to electronic lexicography: The Corpus-based Dictionary of Polish Sign Language and beyond. The interview was conducted by Dr. Victoria Nyst from Leiden University, Faculty of Humanities, and Dr. Iztok Kosem from the University of Ljubljana, Faculty of Arts.

  9. Analysis of mechanical preparations in extracted teeth using ProTaper rotary instruments: value of the safety quotient.

    Science.gov (United States)

    Blum, J Y; Machtou, P; Ruddle, C; Micallef, J P

    2003-09-01

    The purpose of this study was to apply the Endographe to analyze the vertical forces and torque developed during mechanical preparations in extracted teeth. The data collected in this study may be used to calculate the safety quotient (SQ) as proposed by J.T. McSpadden. The SQ formula is defined as the torque required to break a file at D3 divided by the mean working torque required to cut dentin. The Endographe is a unique force-analyzer device equipped to measure, record, and generate graphs of the vertical forces and torque exerted during root canal preparation. All preparations were performed by endodontists in roots with narrow, more restrictive canals, larger, more open canals, or in roots sectioned in two halves. All canals, including the sectioned canals, were prepared with ProTaper files in accordance with the manufacturer's guidelines for use. For narrow canals, the mean values of the generated vertical forces (g) and torque (g.cm) varied from 80 (+/- 20) g (SX) to 232 (+/- 60) g (F2) and from 80 (+/- 24) g x cm (F1) to 150 (+/- 45) g x cm (S2), respectively. For large canals, the mean values of the generated vertical forces (g) and torque (g x cm) varied from 80 (+/- 20) g (SX) to 340 (+/- 20) g (F1) and from 31 (+/- 9) g x cm (S2) to 96 (+/- 35) g x cm (SX), respectively. The SQ varied from 0.93 to 7.95 for narrow canals and from 1.58 to 14.50 for large canals. The SQ is intended to provide values that can be analyzed to predict whether a rotary file will have a tendency to break or will work safely during clinical use. However, if the formula is going to provide useful information, it must index the "rotation to failure torque" with the "mean working torque" at a specific location along the cutting blades of a file. Additionally, this mathematical formula does not account for factors such as the concentration of forces, the way the instruments are used, or the wear of the instruments. A precise protocol for canal preparation should emphasize using

  10. Transformation of the Polish Banking Sector

    Directory of Open Access Journals (Sweden)

    Marek Stefański

    2009-07-01

    Full Text Available In the post-war period the banking system in Poland underwent two important system transitions: after 1946 and after 1989. The third transformation began after May 1, 2004, but it did not have a systemic character. The Polish banking sector started to operate on the Single European Market. The first part of the paper is devoted to the problems of the banks transformations after 1989 with a special focus on the quantitative development of banks in 19892008, and on subsequent privatisation and consolidation processes. The former intensified in 19891999, and the latter in 19992002. The consolidation process was very noticeable in the sector of cooperative banks after 1994. The second part of the paper includes an economic and financial analysis of the banks. A lot of attention was paid to the liquidity of the banking sector. It was assessed as good, which was confirmed by a short-term rating of Moodys and by the Financial Stability Report 2009, published by the National Bank of Poland in June 2009. The comparison of the net profit of the banking sector in 19972008 shows its dependence on the economic situation and policy. The number of banks with capital adequacy ratio well above the minimum required by the banking supervision is rising. The financial power ratings are not favorable for the domestic banks. The third part of the paper focuses on the development directions of the Polish banking sector. It may be concluded on the basis of the analysis that privatisation and consolidation processes will be continued. They will concentrate on the capital of foreign banks already operating in Poland. As compared with individual foreign banks, the potential of the Polish banking sector is week. The fourth part of the paper focuses on the presentation Polish banking sector in the context of European Union banking sector. The paper finishes with conclusions. Generally, Polish banks have to implement a strategy to enable them to compete on the Single

  11. Precision machining and polishing of scintillating crystals for large calorimeters and hodoscopes

    International Nuclear Information System (INIS)

    Wuest, C.R.; Fuchs, B.A.

    1993-05-01

    New machining and polishing techniques have been developed for large barium fluoride scintillating crystals that provide crystalline surfaces without sub-surface damage or deformation as verified by Atomic Force Microscopy (AFM) and Rutherford Back-scattering (RBS) analyses. Surface roughness of about 10--20 angstroms and sub-micron mechanical tolerances have been demonstrated on large crystal samples. Mass production techniques have also been developed for machining and polishing up to five 50 cm long crystals at one time. We present this technology along with surface studies of barium fluoride crystals polished with this technique. This technology is applicable for a number of new crystal detectors proposed at Colliders including the Barium Fluoride Electromagnetic Calorimeter at SSC, the Crystal Clear Collaboration's cerium fluoride calorimeter at LHC, and the KTeV and PHENIX scintillating hodoscopes at Fermilab, and RHIC, respectively. Lawrence Livermore National Laboratory (LLNL) has an active program of study on barium fluoride scintillating crystals for the Barium Fluoride Electromagnetic Calorimeter Collaboration and cerium fluoride and lead fluoride for the Crystal Clear Collaboration. This program has resulted in a number of significant improvements in the mechanical processing, polishing and coating of fluoride crystals. Techniques have been developed using diamond-loaded pitch lapping that can produce 15 angstrom RMS surface finishes over large areas. Also, special polishing fixtures have been designed based on mounting technology developed for the 1.1 m diameter optics used in LLNL's Nova Laser. These fixtures allow as many as five 25--50 cm long crystals to be polished and lapped at the same time with tolerances satisfying the stringent requirements of crystal calorimeters. We also discuss results on coating barium fluoride with UV reflective layers of magnesium fluoride and aluminum

  12. Composite films based on biorelated agro-industrial waste and poly(vinyl alcohol). Preparation and mechanical properties characterization.

    Science.gov (United States)

    Chiellini, E; Cinelli, P; Imam, S H; Mao, L

    2001-01-01

    As a part of an ongoing project on the production of composite materials based on poly(vinyl alcohol) (PVA) and polymeric materials from renewable resources, the present paper reports on the incorporation of agricultural waste materials as organic fillers in a film matrix based on PVA as continuous phase. In this study lignocellulosic fibers byproducts, derived from sugar cane (SC) and apple (AP) and orange (OR) fruit juice extraction, were cast from PVA aqueous solutions. The effect of fiber type and composition on the relative properties of cast films was evaluated and compared. OR resulted to be suitable for blending in higher amounts by weight than SC and AP. Glycerol and urea were added as plasticizing agents and were observed to be effective in giving flexible films. Additionally, cornstarch was added to further increase the composition of polymers from renewable resources in cost-effective and ecoefficient composite film formulations. The prepared films resulted sensitive to moisture and water. To reduce water sensitivity, hexamethoxymethylmelamine (HMMM) was tested as a cross-linking agent for the present composite formulations. Cross-linked films exhibited significant improvement in water-resistance that can be taken as a tuneable structural feature for customized applications. The mechanical properties of the prepared composite films (elongation at break, tensile strength, Young modulus) were found to be dependent upon the nature and content of the filler and on environmental conditions.

  13. [On the preparation and mechanical properties of PVA hydrogel bionic cartilage/bone composite artificial articular implants].

    Science.gov (United States)

    Meng, Haoye; Zheng, Yudong; Huang, Xiaoshan; Yue, Bingqing; Xu, Hong; Wang, Yingjun; Chen, Xiaofeng

    2010-10-01

    In view of the problems that conventional artificial cartilages have no bioactivity and are prone to peel off in repeated uses as a result of insufficient strength to bond with subchondral bone, we have designed and prepared a novel kind of PVA-BG composite hydrogel as bionic artificial articular cartilage/bone composite implants. The effects of processes and conditions of preparation on the mechanical properties of implant were explored. In addition, the relationships between compression strain rate, BG content, PVA hydrogels thickness and compressive tangent modulus were also explicated. We also analyzed the effects of cancellous bone aperture, BG and PVA content on the shear strength of bonding interface of artificial articular cartilage with cancellous bone. Meanwhile, the bonding interface of artificial articular cartilage and cancellous bone was characterized by scanning electron microscopy. It was revealed that the compressive modulus of composite implants was correspondingly increased with the adding of BG content and the augments of PVA hydrogel thickness. The compressive modulus and bonding interface were both related to the apertures of cancellous bone. The compressive modulus of composite implants was 1.6-2.23 MPa and the shear strength of bonding interface was 0.63-1.21 MPa. These results demonstrated that the connection between artificial articular cartilage and cancellous bone was adequately firm.

  14. Facile preparation and formation mechanism of Sr2Si5N8:Eu2+ red-emitting phosphors

    Science.gov (United States)

    Wang, Yang; Wang, Yunli; Wang, Ming; Shao, Yiran; Zhu, Yingchun

    2018-05-01

    The red-emitting Sr2Si5N8:Eu2+ phosphors have been synthesized in a new facile process using (oxy)nitride precursors by inductive calcination under N2 atmosphere at ordinary pressure. Different from the prevailing methods, lower cost raw materials, simpler pretreatment, without harsh conditions and a shorter reaction time are achieved. It was found that red-emitting Sr2Si5N8:Eu2+ phosphors were synthesized with high crystallinity and purity after 1 h inductive calcination. The formation mechanism was characterized by XRD, SEM, TEM and Fluorescence microscopy. It was demonstrated that a hexagonal mesophase of Sr-doped α-Si3N4 was primarily formed in the reaction process, which transformed into the final product of the orthorhombic Sr2Si5N8:Eu2+ phosphors. During the reaction process, the color of the samples transforms from greenish-yellow to orange and eventually to red. The as-prepared phosphors have a wide excitation in the range of 250 ∼ 570 nm which matches blue light chips and give a red-light emission peaking at 610 nm. The results indicate a promising prospect for a simple, efficient and inexpensive way to prepare Sr2Si5N8:Eu2+ phosphors for blue/UV-based warm-white LEDs and other fluorescent applications.

  15. Comparison of the Nanostructure and Mechanical Performance of Highly Exfoliated Epoxy-Clay Nanocomposites Prepared by Three Different Protocols

    Directory of Open Access Journals (Sweden)

    Fatemeh Shiravand

    2014-05-01

    Full Text Available Three different protocols for the preparation of polymer layered silicate nanocomposites based upon a tri-functional epoxy resin, triglycidyl para-amino phenol (TGAP, have been compared in respect of the cure kinetics, the nanostructure and their mechanical properties. The three preparation procedures involve 2 wt% and 5 wt% of organically modified montmorillonite (MMT, and are: isothermal cure at selected temperatures; pre-conditioning of the resin-clay mixture before isothermal cure; incorporation of an initiator of cationic homopolymerisation, a boron tri-fluoride methyl amine complex, BF3·MEA, within the clay galleries. It was found that features of the cure kinetics and of the nanostructure correlate with the measured impact strength of the cured nanocomposites, which increases as the degree of exfoliation of the MMT is improved. The best protocol for toughening the TGAP/MMT nanocomposites is by the incorporation of 1 wt% BF3·MEA into the clay galleries of nanocomposites containing 2 wt% MMT.

  16. A study of the kinetics and mechanisms of electrocrystallization of indium oxide on an in situ prepared metallic indium electrode

    International Nuclear Information System (INIS)

    Omanovic, S.; Metikos-Hukovic, M.

    2004-01-01

    The mechanisms and kinetics of nucleation and growth of indium oxide film on an in situ prepared metallic indium electrode was studied in a borate buffer solution of pH 10.0 using cyclic voltammetry and chroanoamperometry techniques. It was shown that the initial stage of nucleation of the oxide film includes a three-dimensional progressive nucleation process, combined with a diffusion-controlled growth of the stable indium oxide crystals. The thermodynamic data obtained indicated a strong tendency of indium to form an indium oxide film on its surface in an aqueous solution. It was found that the rate-determining step in the nucleation and growth process is the surface diffusion of electroactive species. The nucleation rate constant, and the number of nucleation active sites were calculated independently. It was shown that between 2 and 15% of sites on the indium surface act as active nucleation centers, and that each active site represents a critical nucleus

  17. Process controls for Bi2Te3-Sb2Te3 prepared by mechanical alloying and hot pressing

    International Nuclear Information System (INIS)

    Lee, Go-Eun; Kim, Il-Ho; Choi, Soon-Mok; Lim, Young-Soo; Seo, Won-Seon; Park, Jae-Soung; Yang, Seung-Ho

    2014-01-01

    p-Type Bi 2 Te 3 -Sb 2 Te 3 solid solutions were prepared by mechanical alloying (MA) and hot pressing (HP) under different process conditions, after which the transport and the thermoelectric properties were evaluated. The relative densities of all hot-pressed specimens were over 98%, and the microstructure and crystal orientation were independent of the HP direction. All specimens exhibited p-type conduction, and the electrical resistivity was observed to increase slightly with increasing temperature, indicating a degenerate semiconductor behavior. The carrier concentration decreased with increasing HP temperature while the mobility increased. The maximum figure of merit obtained was 0.86 at 323 K for Bi 0.5 Sb 1.5 Te 3 hot-pressed at 648 K.

  18. Effect of chip size on mechanical property and microstructure of AZ91D magnesium alloy prepared by solid state recycling

    International Nuclear Information System (INIS)

    Hu Maoliang; Ji Zesheng; Chen Xiaoyu; Zhang Zhenkao

    2008-01-01

    In this study, different kinds of AZ91D magnesium alloy chips were prepared by solid state recycling. Mechanical properties and microstructures of the recycled specimens were investigated. Various microstructural analyses were performed using the techniques of optical microscopy, scanning electron microscopy and oxygen-nitrogen analysis. Microstructural observations revealed that all the recycled specimens consisted of fine grains due to dynamic recrystallization. The oxide precipitate content is closely related to the recycled chip size. Accumulated oxygen concentration linearly increases with the total surface area of the machined chips in the recycled specimens. Ambient oxide in the recycled specimen contributes to a higher ultimate tensile strength and a higher elongation to failure; however, excessive oxide in the recycled specimen may adversely affect the elongation to failure

  19. Radiation preparation of graphene/carbon nanotubes hybrid fillers for mechanical reinforcement of poly(vinyl alcohol) films

    Science.gov (United States)

    Ma, Hui-Ling; Zhang, Long; Zhang, Youwei; Wang, Shuojue; Sun, Chao; Yu, Hongyan; Zeng, Xinmiao; Zhai, Maolin

    2016-01-01

    Graphene/carbon nanotubes (G/CNTs) hybrid fillers were synthesized by γ-ray radiation reduction of graphene oxide (GO) in presence of CNTs. The obtained hybrid fillers with three-dimensional (3D) interconnected network structure were characterized by X-ray diffraction (XRD) and scanning electron microscope (SEM). Poly(vinyl alcohol) (PVA) composite films with enhanced mechanical properties and thermal stability were subsequently prepared by solution blending of G/CNTs with PVA matrix. The tensile strength and Young's modulus of PVA composite films containing 1 wt% G/CNTs were measured to be 81.9 MPa and 3.9 GPa respectively, which were 56% and 33.6% higher than those of pure PVA. These substantial improvements could be attributed to the interconnected 3D structure of G/CNTs, homogeneous dispersion as well as the strong hydrogen-bonding interaction between G/CNTs and PVA macromolecular chains.

  20. Tetragonal zirconia ceramics in Zr O2-Ce O2 system (Ce-TZP): preparation, characterization and mechanical properties

    International Nuclear Information System (INIS)

    Andrade Nono, M.C. de.

    1992-01-01

    This paper describes and discusses the results achieved in a study about Ce-TZP ceramics prepared from conventional powder mixtures of Zr O 2 and Ce O 2 (with composition in the range of 8 to 16 mol% Ce O 2 ). Physical and chemical characteristics were related with the powder compaction behavior and with the sintering state. The sintered ceramics showed a level of high porosity (≅ 4%), mainly due to the fairly adequate powder characteristics and compaction. The crystalline phases were analysed from X-rays diffraction data and showed that these ceramics can present tetragonal-to-monoclinic stress induced transformation. The bending strength, fracture toughness and Vickers hardness results were influenced by Ce O 2 content microstructure and sintering temperature. These Ce-TZP ceramics showed mechanical strength results comparable to those published in the international literature. (author)

  1. Morphology, thermal and mechanical properties of PVC/MMT nanocomposites prepared by solution blending and solution blending + melt compounding

    DEFF Research Database (Denmark)

    Madaleno, Liliana Andreia Oliveira; Schjødt-Thomsen, Jan; Pinto, José Cruz

    2010-01-01

    Two types of montmorillonite (MMT), natural sodium montmorillonite (Na-MMT) and organically modified montmorillonite (OMMT), in different amounts of 1, 2, 5, 10 and 25 phr (parts per hundred resin), were dispersed in rigid poly (vinyl chloride) by two different methods solution blending...... and solution blending + melt compounding The effects on morphology, thermal and mechanical properties of the PVC/MMT nanocomposites were studied by varying the amount of Na-MMT and OMMT in both methods SEM and XRD analysis revealed that possible intercalated and exfoliated structures were obtained in all...... prepared by solution blending + melt compounding method Experimental values for 1 and 2 phr are larger than the calculated values which directly suggest that the MMT particles are exfoliated (C) 2010 Elsevier Ltd All rights reserved...

  2. Surface Roughness and Gloss of Actual Composites as Polished With Different Polishing Systems.

    Science.gov (United States)

    Rodrigues-Junior, S A; Chemin, P; Piaia, P P; Ferracane, J L

    2015-01-01

    This in vitro study evaluated the effect of polishing with different polishing systems on the surface roughness and gloss of commercial composites. One hundred disk-shaped specimens (10 mm in diameter × 2 mm thick) were made with Filtek P-90, Filtek Z350 XT, Opallis, and Grandio. The specimens were manually finished with #400 sandpaper and polished by a single operator using three multistep systems (Superfix, Diamond Pro, and Sof-lex), one two-step system (Polidores DFL), and one one-step system (Enhance), following the manufacturer's instructions. The average surface roughness (μm) was measured with a surface profilometer (TR 200 Surface Roughness Tester), and gloss was measured using a small-area glossmeter (Novo-Curve, Rhopoint Instrumentation, East Sussex, UK). Data were analyzed by two-way analysis of variance and Tukey's test (α=0.05). Statistically significant differences in surface roughness were identified by varying the polishing systems (pGloss was influenced by the composites (pone-step system, Enhance, produced the lowest gloss for all composites. Surface roughness and gloss were affected by composites and polishing systems. The interaction between both also influenced these surface characteristics, meaning that a single polishing system will not behave similarly for all composites. The multistep systems produced higher gloss, while the one-step system produced the highest surface roughness and the lowest gloss of all.

  3. Mechanical properties and thermal stability of Al–Fe–Ni alloys prepared by centrifugal atomisation and hot extrusion

    International Nuclear Information System (INIS)

    Průša, F.; Vojtěch, D.; Michalcová, A.; Marek, I.

    2014-01-01

    In this work, Al–12Fe and Al–7Fe–5Ni (wt%) alloys prepared by a novel technique including centrifugal atomisation and hot extrusion were studied. The microstructures were investigated using light microscopy, electron scanning microscopy, transmission electron microscopy and X-ray diffraction. The mechanical properties were determined by Vickers hardness measurements and compressive stress–strain tests. To study the thermal stability, the mechanical properties were also measured after 100 h of annealing at 300 °C and 400 °C. In addition, creep tests at a stress of 120 MPa and a temperature of 300 °C were performed. The investigated materials were composed of fine-grained α-Al and intermetallic phases identified as Al 13 Fe 4 and Al 9 FeNi. The Vickers hardness and compressive yield strength were 68 HV5 and 183 MPa, respectively, for the Al–12Fe alloy and 73 HV5 and 226 MPa, respectively, for the Al–7Fe–5Ni alloy. After long-term annealing, the change in the mechanical properties was negligible, indicating the excellent thermal stability of both materials. The creep tests confirmed the highest thermal stability of the Al–7Fe–5Ni alloy with a total compressive creep strain of 15%. The “thermally stable” casting Al–12Si–1Cu–1Mg–1Ni alloy treated by the T6 regime was used as a reference material. The casting alloy exhibited sufficient mechanical properties (hardness and compressive yield strength) at room temperature. However, annealing remarkably softened and reduced its compressive yield strength to almost 50% of the initial values. Additionally, the total creep strain of the casting reference material was almost three times higher than that of the Al–7Fe–5Ni alloy. It has been proven that centrifugally atomised materials quickly compacted via hot extrusion can compete or even exceed the properties of common casting aluminium alloys that are used in automotive industry

  4. Fusion - 2050 perspective (in Polish)

    CERN Document Server

    Romaniuk, R S

    2013-01-01

    The results of strongly exothermic reaction of thermonuclear fusion between nuclei of deuterium and tritium are: helium nuclei and neutrons, plus considerable kinetic energy of neutrons of over 14 MeV. DT nuclides synthesis reaction is probably not the most favorable one for energy production, but is the most advanced technologically. More efficient would be possibly aneutronic fusion. The EU by its EURATOM agenda prepared a Road Map for research and implementation of Fusion as a commercial method of thermonuclear energy generation in the time horizon of 2050.The milestones on this road are tokomak experiments JET, ITER and DEMO, and neutron experiment IFMIF. There is a hope, that by engagement of the national government, and all research and technical fusion communities, part of this Road Map may be realized in Poland. The infrastructure build for fusion experiments may be also used for material engineering research, chemistry, biomedical, associated with environment protection, power engineering, security, ...

  5. Preparation and mechanical properties of in situ TiC{sub x}–Ni (Si, Ti) alloy composites

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Wenjuan [Institute of Materials Science and Engineering, School of Mechanical, Electronic and Control Engineering, Beijing Jiaotong University, Beijing 100044 (China); Zhai, Hongxiang, E-mail: hxzhai@sina.com [Institute of Materials Science and Engineering, School of Mechanical, Electronic and Control Engineering, Beijing Jiaotong University, Beijing 100044 (China); Chen, Lin; Huang, Zhenying [Institute of Materials Science and Engineering, School of Mechanical, Electronic and Control Engineering, Beijing Jiaotong University, Beijing 100044 (China); Bei, Guoping; Baumgärtner, Christoph; Greil, Peter [Department of Materials Science (Glass and Ceramics), University of Erlangen-Nuernberg, Martensstr. 5, 91058 Erlangen (Germany)

    2014-10-20

    Novel in situ TiC{sub x} reinforced Ni (Si, Ti) alloy composites with superior mechanical properties were prepared at 1250 °C for 30 min by pressureless sintering Ti{sub 3}SiC{sub 2} (10 and 20 vol%) and Ni as precursors. The Ti{sub 3}SiC{sub 2} particles decomposed into substoichiometric TiC{sub x} phase, while the additional Si and partial Ti atoms derived from Ti{sub 3}SiC{sub 2} diffused into Ni matrix to form Ni (Si, Ti) alloy. The in situ formed TiC{sub x} phases are mainly dispersed on the grain boundaries of the Ni (Si, Ti) alloying, forming a strong skeleton and refining the microstructures of the metal matrix. The hardness, the yield stress σ{sub 0.2%} and ultimate compressive strength of 20.6 vol%TiC{sub x}–Ni(Si, Ti) composite can reach 2.15±0.04 GPa, 466.8±55.8 MPa and 733.3±78.4 MPa, respectively. The enhanced mechanical properties of TiC{sub x}–Ni(Si, Ti) composites are due to the in situ formation of TiC{sub x} skeleton, the refined microstructures of Ni (Si, Ti) alloys and solid solution effects as well as good wettability between TiC{sub x} and Ni (Si, Ti) matrix.

  6. Textures and mechanical properties in rare-earth free quasicrystal reinforced Mg-Zn-Zr alloys prepared by extrusion

    International Nuclear Information System (INIS)

    Ohhashi, S.; Kato, A.; Demura, M.; Tsai, A.P.

    2011-01-01

    Highlights: → Powder-metallurgical warm extrusion made quasicrystal dispersing Mg alloys. → Mg extrusions containing quasicrystals showed randomized textures. → These extrusion showed the enhancement of mechanical properties at 150 deg. C. - Abstract: Microstructure and mechanical properties of quasicrystals dispersed Mg alloys prepared by warm extrusion of the mixtures of Mg and Zn-Mg-Zr quasicrystalline (Qc) powders have been studied. Strong texture oriented along a [101-bar 0] direction observed in pure Mg was reduced in Qc-dispersed samples, as verified by pole figure method and electron back scattering diffraction. The ultimate tensile strengths at 150 deg. C for Qc-dispersed extrusions were much higher than 110 MPa for pure Mg, which drastically reached 156 MPa for 15 wt.% Qc by preventing the motion of dislocations. Elongation was improved by the randomization of grain orientation: from 5.7% for pure Mg to 12.9% for 10 wt.% Qc at room temperature; from 15% for pure Mg to 37.1% for 5 wt.% Qc at 150 deg. C.

  7. Evolution of Thermoelectric Properties of Zn4Sb3 Prepared by Mechanical Alloying and Different Consolidation Routes

    Directory of Open Access Journals (Sweden)

    Pee-Yew Lee

    2018-05-01

    Full Text Available In this research, a method combining the mechanical alloying with the vacuum sintering or hot pressing was adopted to obtain the compact of β-Zn4Sb3. Pure zinc and antimony powders were used as the starting material for mechanical alloying. These powders were mixed in the stoichiometry ratio of 4 to 3, or more Zn-rich. Single phase Zn4Sb3 was produced using a nominally 0.6 at. % Zn rich powder. Thermoelectric Zn4Sb3 bulk specimens have been fabricated by vacuum sintering or hot pressing of mechanically alloyed powders at various temperatures from 373 to 673 K. For the bulk specimens sintering at high temperature, phase transformation of β-Zn4Sb3 to ZnSb and Sb was observed due to Zn vaporization. However, single-phase Zn4Sb3 bulk specimens with 97.87% of theoretical density were successfully produced by vacuum hot pressing at 473 K. Electric resistivity, Seebeck coefficient, and thermal conductivity were evaluated for the hot pressed specimens from room temperature to 673 K. The results indicate that the Zn4Sb3 shows an intrinsic p-type behavior. The increase of Zn4Sb3 phase ratio can increase Seebeck coefficient but decrease electric conductivity. The maximum power factor and figure of merit (ZT value were 1.31 × 10−3 W/mK2 and 0.81 at 600 K, respectively. The ZT value was lower than that reported in the available data for materials prepared by conventional melt growth and hot pressed methods, but higher than the samples fabricated by vacuum melting and heat treatment techniques.

  8. Hydrogen storage properties in the Mg_0_._7_5Ta_0_._2_5 system prepared by mechanical milling

    International Nuclear Information System (INIS)

    Ramirez G, J. A.

    2016-01-01

    Magnesium and most of its mixtures have slow sorption-desorption kinetics of hydrogen, which limits their technological application and their viability from the economic view point. Recently, has been observed that by the synthesis of advanced materials, using the mechanical milling technique, positive changes in the kinetics are introduced. In order to improve the sorption-desorption hydrogen properties, in the present work a mixture consisting of Mg_0_._7_5Ta_0_._2_5 was prepared using methanol as process control agent. To this end, the first methodological step was to carry out, by means of the mechanical milling technique, the synthesis of the mixture Mg_0_._7_5Ta_0_._2_5 in a Spex type vibratory mill at times of 6, 12, 18 and 24 h. Subsequently, the material was characterized by different analytical techniques such as scanning electron microscopy with elemental analysis, X-ray diffraction and N_2 physisorption analysis. Subsequently, hydrogen sorption experiments were carried out in a Parr reactor to evaluate the hydrogen storage capacity of the mixture, varying temperature parameters, pressure and time, in order to determine the optimal parameters of hydrogen sorption. The characterization of the hydrogen storage capacity was analyzed by the thermogravimetric analysis/differential scanning calorimetry technique coupled to a mass spectrometer. X ray diffraction analysis reveals that there is a mixture between the starting compounds, with an important refinement of the microstructure as a consequence of the mechanical milling process. The results of the hydrogen sorption tests at 1, 5 and 10 cycles showed that the storage of hydrogen in the Mg_0_._7_5Ta_0_._2_5 mixture can be carried out at a temperature of 25 degrees Celsius with a pressure of 2 atm and a contact time of 1 h. (Author)

  9. Surface roughness and hardness of a composite resin: influence of finishing and polishing and immersion methods

    Directory of Open Access Journals (Sweden)

    Ana Luísa Botta Martins de Oliveira

    2010-09-01

    Full Text Available This study evaluated the finishing and polishing effect on the surface roughness and hardness of the Filtek Supreme XT, in fluoride solutions. Specimens were prepared (n = 140 with half of the samples finished and polished with Super-Snap® disks. The experimental groups were divided according to the presence or absence of finishing and polishing and immersion solutions (artificial saliva, sodium fluoride solution at 0.05% - manipulated, Fluordent Reach, Oral B, Fluorgard. The specimens remained immersed in artificial saliva for 24 hours and were then subjected to initial analysis (baseline of surface roughness and Vickers microhardness. Next, they were immersed in different fluoride solutions for 1 min/day, for 60 days. Afterwards, a new surface roughness and microhardness reading was conducted. The data were submitted to a two-way ANOVA and Tukey's test (5% significance level. For the comparison of mean roughness and hardness at baseline and after 60 days, the paired Student t test was used. The results showed that the surface roughness and microhardness of the Filtek Supreme XT were influenced by the finishing and polishing procedure, independently of the immersion methods.

  10. Structural evolution of Cu{sub (1−X)}Y{sub X} alloys prepared by mechanical alloying: Their thermal stability and mechanical properties

    Energy Technology Data Exchange (ETDEWEB)

    Mula, Suhrit, E-mail: smulafmt@iitr.ernet.in [Department of Metallurgical and Materials Engineering, Indian Institute of Technology Roorkee, Roorkee 247667 (India); Setman, Daria [Physics of Nanostructured Materials, University of Vienna, Boltzmanngasse 5, A-1090 Wien (Austria); Youssef, Khaled [Department of Materials Science and Technology, Qatar University, P.O. Box 2713, Doha (Qatar); Scattergood, R.O.; Koch, Carl C [Department of Materials Science and Engineering, NC State University, Raleigh, NC 27695 (United States)

    2015-04-05

    Highlights: • Metastable solid solutions were prepared from Cu–Y nonequilibrium compositions by mechanical alloying. • Gibbs free energy change as per Miedema’s model confirms the formation of metastable alloys. • High Y content alloys showed high thermal stability during extensive annealing at high temperatures. • Stabilized alloys showed very high hardness and improved yield strength. • Mechanisms of high thermal stability and improved mechanical properties were discussed. - Abstract: In the present study, an attempt has been made to synthesize copper based disordered solid solutions by mechanical alloying (MA) of non-equilibrium compositions. The blended compositions of Cu–1% Y, Cu–3% Y, Cu–5% Y and Cu–7.5% Y (at.%) (all the compositions will be addressed as % only hereafter until unless it is mentioned) were ball-milled for 8 h, and then annealed at different temperatures (200–800 °C) for different length of duration (1–5 h) under high purity argon + 2 vol.% H{sub 2} atmosphere. X-ray diffraction (XRD) analysis and Gibbs free energy change calculation confirm the formation of disordered solid solution (up to 7.5%) of Y in Cu after milling at a room temperature for 8 h. The XRD grain size was calculated to be as low as 7 nm for 7.5% Y and 22 nm for 1% Y alloy. The grain size was retained within 35 nm even after annealing for 1 h at 800 °C. Transmission electron microscopy (TEM) analysis substantiates the formation of ultra-fine grained nanostructures after milling. Microhardness value of the as-milled samples was quite high (3.0–4.75 GPa) compared to that of pure Cu. The hardness value increased with increasing annealing temperatures up to 400 °C for the alloys containing 3–7.5% Y, and thereafter it showed a decreasing trend. The increase in the hardness after annealing is attributed to the formation of uniformly distributed ultrafine intermetallic phases in the nanocrystalline grains. The stabilization effect is achieved due to

  11. Understanding the creation of & reducing surface microroughness during polishing & post-processing of glass optics

    Energy Technology Data Exchange (ETDEWEB)

    Suratwala, Tayyab [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2016-09-22

    In the follow study, we have developed a detailed understanding of the chemical and mechanical microscopic interactions that occur during polishing affecting the resulting surface microroughness of the workpiece. Through targeted experiments and modeling, the quantitative relationships of many important polishing parameters & characteristics affecting surface microroughness have been determined. These behaviors and phenomena have been described by a number of models including: (a) the Ensemble Hertzian Multi Gap (EHMG) model used to predict the removal rate and roughness at atomic force microscope (AFM) scale lengths as a function of various polishing parameters, (b) the Island Distribution Gap (IDG) model used to predict the roughness at larger scale lengths, (c) the Deraguin-Verwey-Landau-Overbeek (DLVO) 3-body electrostatic colloidal model used to predict the interaction of slurry particles at the interface and roughness behavior as a function of pH, and (d) a diffusion/chemical reaction rate model of the incorporation of impurities species into the polishing surface layer (called the Bielby layer). Based on this improved understanding, novel strategies to polish the workpiece have been developed simultaneously leading to both ultrasmooth surfaces and high material removal rates. Some of these strategies include: (a) use of narrow PSD slurries, (b) a novel diamond conditioning recipe of the lap to increase the active contact area between the workpiece and lap without destroying its surface figure, (c) proper control of pH for a given glass type to allow for a uniform distribution of slurry particles at the interface, and (d) increase in applied load just up to the transition between molecular to plastic removal regime for a single slurry particle. These techniques have been incorporated into a previously developed finishing process called Convergent Polishing leading to not just economical finishing process with improved surface figure control, but also

  12. Microbiological Safety of Commercial Prime Rib Preparation Methods: Thermal Inactivation of Salmonella in Mechanically Tenderized Rib Eye.

    Science.gov (United States)

    Calle, Alexandra; Porto-Fett, Anna C S; Shoyer, Bradley A; Luchansky, John B; Thippareddi, Harshavardhan

    2015-12-01

    Boneless beef rib eye roasts were surface inoculated on the fat side with ca. 5.7 log CFU/g of a five-strain cocktail of Salmonella for subsequent searing, cooking, and warm holding using preparation methods practiced by restaurants surveyed in a medium-size Midwestern city. A portion of the inoculated roasts was then passed once through a mechanical blade tenderizer. For both intact and nonintact roasts, searing for 15 min at 260°C resulted in reductions in Salmonella populations of ca. 0.3 to 1.3 log CFU/g. For intact (nontenderized) rib eye roasts, cooking to internal temperatures of 37.8 or 48.9°C resulted in additional reductions of ca. 3.4 log CFU/g. For tenderized (nonintact) rib eye roasts, cooking to internal temperatures of 37.8 or 48.9°C resulted in additional reductions of ca. 3.1 or 3.4 log CFU/g, respectively. Pathogen populations remained relatively unchanged for intact roasts cooked to 37.8 or 48.9°C and for nonintact roasts cooked to 48.9°C when held at 60.0°C for up to 8 h. In contrast, pathogen populations increased ca. 2.0 log CFU/g in nonintact rib eye cooked to 37.8°C when held at 60.0°C for 8 h. Thus, cooking at low temperatures and extended holding at relatively low temperatures as evaluated herein may pose a food safety risk to consumers in terms of inadequate lethality and/or subsequent outgrowth of Salmonella, especially if nonintact rib eye is used in the preparation of prime rib, if on occasion appreciable populations of Salmonella are present in or on the meat, and/or if the meat is not cooked adequately throughout.

  13. Emissions from the Polish power industry

    International Nuclear Information System (INIS)

    Uliasz-Bochenczyk, Alicja; Mokrzycki, Eugeniusz

    2007-01-01

    Poland is a country where power and heat energy production is based on conventional fuel combustion, above all hard coal and lignite. In power plants and combined heat and power plants, fossil fuel combustion results in emitting to the atmosphere first of all SO 2 , NO x , CO, particulate matter, greenhouse gases for instance N 2 O and CO 2 . For many years the Polish power industry has tried to reduce the emission of air contaminants to the atmosphere. The reduction is feasible on account of various methods of emission reduction, which have been advanced and applied for many years. The paper presents conventional fuels used in the Polish professional power industry, as well as the principal emission types occurring there for the last 10 years and the undertaken reduction measures

  14. Synchrotron/crystal sample preparation

    Science.gov (United States)

    Johnson, R. Barry

    1993-01-01

    The Center for Applied Optics (CAO) of the University of Alabama in Huntsville (UAH) prepared this final report entitled 'Synchrotron/Crystal Sample Preparation' in completion of contract NAS8-38609, Delivery Order No. 53. Hughes Danbury Optical Systems (HDOS) is manufacturing the Advanced X-ray Astrophysics Facility (AXAF) mirrors. These thin-walled, grazing incidence, Wolter Type-1 mirrors, varying in diameter from 1.2 to 0.68 meters, must be ground and polished using state-of-the-art techniques in order to prevent undue stress due to damage or the presence of crystals and inclusions. The effect of crystals on the polishing and grinding process must also be understood. This involves coating special samples of Zerodur and measuring the reflectivity of the coatings in a synchrotron system. In order to gain the understanding needed on the effect of the Zerodur crystals by the grinding and polishing process, UAH prepared glass samples by cutting, grinding, etching, and polishing as required to meet specifications for witness bars for synchrotron measurements and for investigations of crystals embedded in Zerodur. UAH then characterized these samples for subsurface damage and surface roughness and figure.

  15. Polish normalization of the Body Esteem Scale

    Directory of Open Access Journals (Sweden)

    Małgorzata Lipowska

    2014-02-01

    Full Text Available Background Physical attractiveness plays an important part in one’s social functioning. The interest in one’s own appearance have been documented as widespread among the female population, but over the recent years it is more and more often emphasized that concentrating on body appearance concerns men as well. Franzoi and Shields (1984 created the Body Esteem Scale which allows to qualify the subject’s attitude towards his or her own body. The aim of the study was to create a Polish version of the Body Esteem Scale along with the norms for age and sex clusters. Participants and procedure The normalization sample consisted of 4298 participants: 1865 women aged 16 to 80 (M = 29.92; SD = 12.85 and 2433 men aged 16 to 78 (M = 28.74; SD = 11.50. Education levels among the participants were also controlled for. In order to create a Polish version of the Body Esteem Scale, translation was adopted as the adaptation strategy. Like the original one, the Polish scale comprises 35 items grouped into three gender specific subscales. The subscales for women include Sexual Attractiveness, Weight Concern, and Physical Condition, whereas the body esteem of is examined with regards to Physical Attractiveness, Upper Body Strength, and Physical Condition. Results Reliability of subscales was high both for females (Cronbach’s alpha from 0.80 to 0.89 and males (Cronbach’s alpha from 0.85 to 0.88. The given coefficients of reliability cover the original division into subscales adopted by the authors of BES. Conclusions We confirmed high reliability of the Polish version of the Body Esteem Scale, thus we recommend it as a diagnostic tool. Created norms allowed to refer results obtained in the course of research carried out on people with various disorders (e.g. eating disorders or body dysmorphic disorder with population data for corresponding age brackets.

  16. Microstructures, Mechanical Properties and Thermal Conductivities of W-0.5 wt.%TiC Alloys Prepared via Ball Milling and Wet Chemical Method

    Science.gov (United States)

    Lang, Shaoting; Yan, Qingzhi; Sun, Ningbo; Zhang, Xiaoxin; Ge, Changchun

    2017-10-01

    Two kinds of W-0.5 wt.%TiC alloys were prepared, one by ball milling and the other by the wet chemical method. For comparison, pure tungsten powders were chemically prepared and sintered by the same process. The microstructures, mechanical properties and thermal conductivities of the prepared samples were characterized. It has been found that the wet chemical method resulted in finer sizes and more uniform distribution of TiC particles in the sintered tungsten matrix than the ball milling method. The W-TiC alloy prepared by the wet chemical method achieved the highest bending strength (1065.72 MPa) among the samples. Further, it also exhibited obviously higher thermal conductivities in the temperature range of room temperature to 600°C than did the W-TiC alloy prepared by ball milling, but the differences in their thermal conductivities could be ignored in the range of 600-800°C.

  17. Preparation and characterisation of Co–Fe–Ni–M-Si–B (M = Zr, Ti) amorphous powders by wet mechanical alloying

    Energy Technology Data Exchange (ETDEWEB)

    Neamţu, B.V., E-mail: Bogdan.Neamtu@stm.utcluj.ro [Materials Science and Engineering Department, Technical University of Cluj-Napoca, 103-105, Muncii Avenue, 400641, Cluj-Napoca (Romania); Chicinaş, H.F.; Marinca, T.F. [Materials Science and Engineering Department, Technical University of Cluj-Napoca, 103-105, Muncii Avenue, 400641, Cluj-Napoca (Romania); Isnard, O. [Université Grenoble Alpes, Institut NEEL, F-38042, Grenoble (France); CNRS, Institut NEEL, 25 rue des martyrs, BP166, F-38042, Grenoble (France); Chicinaş, I. [Materials Science and Engineering Department, Technical University of Cluj-Napoca, 103-105, Muncii Avenue, 400641, Cluj-Napoca (Romania)

    2016-07-15

    Co-based amorphous alloys were prepared via wet mechanical alloying process starting from elemental powders. The reference alloy Co{sub 70}Fe{sub 4}Ni{sub 2}Si{sub 15}B{sub 9} (at. %) as well as the alloys derived from this composition by the substitution of 5 at.% of Zr or Ti for Si or B (Co{sub 70}Fe{sub 4}Ni{sub 2}Si{sub 15}B{sub 4}Zr{sub 5}, Co{sub 70}Fe{sub 4}Ni{sub 2}Si{sub 15}B{sub 4}Ti{sub 5}, Co{sub 70}Fe{sub 4}Ni{sub 2}Si{sub 10}B{sub 9}Zr{sub 5} and Co{sub 70}Fe{sub 4}Ni{sub 2}Si{sub 10}B{sub 9}Ti{sub 5}) are obtained in amorphous state, according to X-ray diffraction (XRD) investigation, after 40 h of milling. The calculated amount of amorphous fraction reaches 99% after 40 h of milling. The largest increase of the crystallisation temperature was induced by the substitution of Zr or Ti for Si while, regardless of the type of substitution, an important increase of the Curie temperature of the alloy was obtained. A Co-based solid solution, with Co{sub 2}Si and Co{sub 2}B phases, result after crystallisation of the amorphous alloys as proved by XRD investigations. Saturation magnetisation of the alloys decreases upon increasing milling time, however it remains larger than the saturation magnetisation of the reference alloy. This was discussed in correlation with the specificity of the wet mechanical alloying process and the influence of the chemical bonding between Co and metalloids atoms over the magnetic moment of Co. - Highlights: • Co–Fe–Ni–M-Si–B (M = Zr, Ti) amorphous powders were prepared by wet MA. • Amorphisation of the alloy is reached after 40 h of wet MA for any composition. • Magnetisation decrease upon increasing milling time. • Substituting 5% Zr/Ti for Si increases significantly the alloy's thermal stability. • Substitution of 5 at. % Zr/Ti for Si increases the saturation magnetisation by 20%.

  18. Nanometer, submicron and micron sized aluminum powder prepared by semi-solid mechanical stirring method with addition of ceramic particles

    International Nuclear Information System (INIS)

    Qin, X.H.; Jiang, D.L.; Dong, S.M.

    2004-01-01

    Composite powder, which is a mixture of Al/Al 2 O 3 composite particles and nanometer, submicron and micron sized aluminum powder, was prepared by semi-solid mechanical stirring method with addition of Al 2 O 3 ceramic particles. The ceramic particles have an average diameter of 80 μm and a volume fraction of 15% in the slurry. The methods used to measure the size distribution of particles greater than 50 μm and less than 50 μm were sieve analysis and photosedimentation, respectively. The surface morphology and transverse sections of the composite powder of different sizes were examined by scanning electron microscope (SEM), optical microscope and auger electron spectroscopy (AES). The results indicate that the composite powder prepared in present work have a wide size distribution ranging from less than 50-900 μm, and the aluminum particles and Al/Al 2 O 3 composite particles are separated and isolated. The particles greater than 200 μm and less than 50 μm are almost pure aluminum powder. The rate of conversion of ingot aluminum into particles less than 1 μm containing nanometer and submicron sizes is 1.777 wt.% in this work. The aluminum powder of different sizes has different shape and surface morphology, quasi-spherical in shape with rough surface for aluminum particles of micron scale, irregular in shape for aluminum particles of submicron scale, and quite close to a globular or an excellent globular in shape for aluminum particles of nanometer size. On the other hand, the surface of ceramic particle was coated by aluminum particles with maximum thickness less than 10 μm containing nanometer and submicron sizes as a single layer. It is suggested that the surface of ceramic particles can provide more nucleation sites for solidification of liquid aluminum and the nucleation of liquid aluminum can take place readily, grow and adhere on the surface of ceramic particles, although it is poorly wetted by the liquid aluminum and the semi-solid slurry can

  19. Robotic Automation in Computer Controlled Polishing

    Science.gov (United States)

    Walker, D. D.; Yu, G.; Bibby, M.; Dunn, C.; Li, H.; Wu, Y.; Zheng, X.; Zhang, P.

    2016-02-01

    We first present a Case Study - the manufacture of 1.4 m prototype mirror-segments for the European Extremely Large Telescope, undertaken by the National Facility for Ultra Precision Surfaces, at the OpTIC facility operated by Glyndwr University. Scale-up to serial-manufacture demands delivery of a 1.4 m off-axis aspheric hexagonal segment with surface precision robots and computer numerically controlled ('CNC') polishing machines for optical fabrication. The objective was not to assess which is superior. Rather, it was to understand for the first time their complementary properties, leading us to operate them together as a unit, integrated in hardware and software. Three key areas are reported. First is the novel use of robots to automate currently-manual operations on CNC polishing machines, to improve work-throughput, mitigate risk of damage to parts, and reduce dependence on highly-skilled staff. Second is the use of robots to pre-process surfaces prior to CNC polishing, to reduce total process time. The third draws the threads together, describing our vision of the automated manufacturing cell, where the operator interacts at cell rather than machine level. This promises to deliver a step-change in end-to-end manufacturing times and costs, compared with either platform used on its own or, indeed, the state-of-the-art used elsewhere.

  20. ROUGHNESS ANALYSIS OF VARIOUSLY POLISHED NIOBIUM SURFACES

    Energy Technology Data Exchange (ETDEWEB)

    Ribeill, G.; Reece, C.

    2008-01-01

    Niobium superconducting radio frequency (SRF) cavities have gained widespread use in accelerator systems. It has been shown that surface roughness is a determining factor in the cavities’ effi ciency and maximum accelerating potential achievable through this technology. Irregularities in the surface can lead to spot heating, undesirable local electrical fi eld enhancement and electron multipacting. Surface quality is typically ensured through the use of acid etching in a Buffered Chemical Polish (BCP) bath and electropolishing (EP). In this study, the effects of these techniques on surface morphology have been investigated in depth. The surface of niobium samples polished using different combinations of these techniques has been characterized through atomic force microscopy (AFM) and stylus profi lometry across a range of length scales. The surface morphology was analyzed using spectral techniques to determine roughness and characteristic dimensions. Experimentation has shown that this method is a valuable tool that provides quantitative information about surface roughness at different length scales. It has demonstrated that light BCP pretreatment and lower electrolyte temperature favors a smoother electropolish. These results will allow for the design of a superior polishing process for niobium SRF cavities and therefore increased accelerator operating effi ciency and power.

  1. Mechanical properties and thermal stability of Al–Fe–Ni alloys prepared by centrifugal atomisation and hot extrusion

    Energy Technology Data Exchange (ETDEWEB)

    Průša, F., E-mail: Filip.Prusa@vscht.cz; Vojtěch, D.; Michalcová, A.; Marek, I.

    2014-05-01

    In this work, Al–12Fe and Al–7Fe–5Ni (wt%) alloys prepared by a novel technique including centrifugal atomisation and hot extrusion were studied. The microstructures were investigated using light microscopy, electron scanning microscopy, transmission electron microscopy and X-ray diffraction. The mechanical properties were determined by Vickers hardness measurements and compressive stress–strain tests. To study the thermal stability, the mechanical properties were also measured after 100 h of annealing at 300 °C and 400 °C. In addition, creep tests at a stress of 120 MPa and a temperature of 300 °C were performed. The investigated materials were composed of fine-grained α-Al and intermetallic phases identified as Al{sub 13}Fe{sub 4} and Al{sub 9}FeNi. The Vickers hardness and compressive yield strength were 68 HV5 and 183 MPa, respectively, for the Al–12Fe alloy and 73 HV5 and 226 MPa, respectively, for the Al–7Fe–5Ni alloy. After long-term annealing, the change in the mechanical properties was negligible, indicating the excellent thermal stability of both materials. The creep tests confirmed the highest thermal stability of the Al–7Fe–5Ni alloy with a total compressive creep strain of 15%. The “thermally stable” casting Al–12Si–1Cu–1Mg–1Ni alloy treated by the T6 regime was used as a reference material. The casting alloy exhibited sufficient mechanical properties (hardness and compressive yield strength) at room temperature. However, annealing remarkably softened and reduced its compressive yield strength to almost 50% of the initial values. Additionally, the total creep strain of the casting reference material was almost three times higher than that of the Al–7Fe–5Ni alloy. It has been proven that centrifugally atomised materials quickly compacted via hot extrusion can compete or even exceed the properties of common casting aluminium alloys that are used in automotive industry.

  2. Effect of nitrogen on the microstructure and mechanical properties of Co-33Cr-9W alloys prepared by dental casting.

    Science.gov (United States)

    Yamanaka, Kenta; Mori, Manami; Torita, Yasuhiro; Chiba, Akihiko

    2018-01-01

    The effect of nitrogen concentration on the mechanical properties of Co-33Cr-9W alloy dental castings fabricated using the "high-Cr and high-N" concept was investigated. Microstructural analysis was performed on the alloys, and findings were discussed in relation to the mechanical properties. Owing to their high nitrogen concentrations (0.25-0.35wt%), all alloys prepared exhibited face-centered cubic (fcc) γ-phase matrices with a-few-millimeter grains consisting of dendritic substructures. Strain-induced martensitic transformations to produce hexagonal close-packed (hcp) ε-phases were not identified under tensile deformation. The precipitation of the intermetallic σ-phase was identified at the interdendritic regions where solidification segregation of Cr and W occurred. The size and chemical composition of this σ-phase did not vary with the bulk nitrogen concentration. Adding nitrogen to the alloys did not alter their tensile yield stress or Vickers hardness values significantly, suggesting that the nitrogen strengthening effect is affected by the manufacturing route as well as local chemistry that is involved in the microstructural evolution during solidification. The tensile ductility, on the other hand, increased with an increase in nitrogen concentration; the alloy with 0.35wt% nitrogen exhibited 21% elongation with a high 0.2% proof stress (589MPa). This significant improvement in ductility was likely caused by the reduction in the amount of σ-phase precipitates at the interdendritic regions following the addition of nitrogen. Copyright © 2017 Elsevier Ltd. All rights reserved.

  3. Mechanical Properties And Microstructure Of AlN/SiCN Nanocomposite Coatings Prepared By R.F.-Reactive Sputtering Method

    Directory of Open Access Journals (Sweden)

    Nakafushi Y.

    2015-06-01

    Full Text Available FIn this work, AlN/SiCN composite coatings were deposited by r.f.-reactive sputtering method using a facing target-type sputtering (FTS apparatus with composite targets consisting of Al plate and SiC chips in a gaseous mixture of Ar and N2, and investigated their mechanical properties and microstructure. The indentation hardness (HIT of AlN/SiCN coatings prepared from composite targets consisting of 8 ~32 chips of SiC and Al plate showed the maximum value of about 29~32 GPa at a proper nitrogen gas flow rate. X-ray diffraction (XRD patterns for the AlN/SiCN composite coatings indicated the presence of the only peeks of hexagonal (B4 structured AlN phase. AlN coatings clarified the columnar structure of the cross sectional view TEM observation. On the other hand, microstructure of AlN/SiCN composite coatings changed from columnar to equiaxed structure with increasing SiCN content. HR-TEM observation clarified that the composite coatings consisted of very fine equiaxial grains of B4 structured AlN phase and amorphous phase.

  4. Microstructure, chemical states, and mechanical properties of V–C–Co coatings prepared by non-reactive magnetron sputtering

    International Nuclear Information System (INIS)

    Zhang, Xiaojuan; Wang, Bo; Zhan, Zhaolin; Huang, Feng

    2013-01-01

    V–C–Co coatings have been prepared by non-reactive magnetron co-sputtering from VC and Co targets. The microstructure, chemical states, and mechanical properties are examined as a function of Co content in the coatings. The coatings are dense, with columnar growth structures. High resolution transmission electron microscopy (HRTEM) studies identify a nanocomposite microstructure for the 12.4 at.% Co coating, in which ligament-like Co-rich regions partially separate the nanocrystalline VC grains. X-ray photoelectron spectroscopy studies reveal a noticeable charge transfer from Co 2p states to C 1s states. This charge transfer, in addition to the ligament-like Co-rich regions as revealed by HRTEM, points to the formation of a strong Co/VC interface. The nanoindentation hardness of the coatings drops steadily with the Co content, from 29 GPa for pure VC to ∼ 21 GPa for the 12.4 at.% Co coating. Meanwhile, the plasticity characteristic increased from 0.42 to 0.53. - Highlights: • Nanocomposite V–C–Co coatings with strong Co/VC interfaces were formed. • Found nanocrystalline VC grains separated by ∼ 1 nm thin Co-rich ligaments. • A noticeable amount of C-Co bonds between VC and Co is identified. • V–C–Co coatings exhibited a higher plasticity characteristic than VC

  5. Microstructure, chemical states, and mechanical properties of V–C–Co coatings prepared by non-reactive magnetron sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Xiaojuan [Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo, Zhejiang 315201 (China); School of Materials Science and Engineering, Kunming University of Science and Technology, Kunming, Yunnan 650000 (China); Wang, Bo [Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo, Zhejiang 315201 (China); Zhan, Zhaolin [School of Materials Science and Engineering, Kunming University of Science and Technology, Kunming, Yunnan 650000 (China); Huang, Feng, E-mail: huangfeng@nimte.ac.cn [Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo, Zhejiang 315201 (China)

    2013-07-01

    V–C–Co coatings have been prepared by non-reactive magnetron co-sputtering from VC and Co targets. The microstructure, chemical states, and mechanical properties are examined as a function of Co content in the coatings. The coatings are dense, with columnar growth structures. High resolution transmission electron microscopy (HRTEM) studies identify a nanocomposite microstructure for the 12.4 at.% Co coating, in which ligament-like Co-rich regions partially separate the nanocrystalline VC grains. X-ray photoelectron spectroscopy studies reveal a noticeable charge transfer from Co 2p states to C 1s states. This charge transfer, in addition to the ligament-like Co-rich regions as revealed by HRTEM, points to the formation of a strong Co/VC interface. The nanoindentation hardness of the coatings drops steadily with the Co content, from 29 GPa for pure VC to ∼ 21 GPa for the 12.4 at.% Co coating. Meanwhile, the plasticity characteristic increased from 0.42 to 0.53. - Highlights: • Nanocomposite V–C–Co coatings with strong Co/VC interfaces were formed. • Found nanocrystalline VC grains separated by ∼ 1 nm thin Co-rich ligaments. • A noticeable amount of C-Co bonds between VC and Co is identified. • V–C–Co coatings exhibited a higher plasticity characteristic than VC.

  6. AC magnetic properties of the soft magnetic composites based on Supermalloy nanocrystalline powder prepared by mechanical alloying

    Energy Technology Data Exchange (ETDEWEB)

    Neamtu, B.V., E-mail: bogdan.neamtu@stm.utcluj.ro [Materials Science and Engineering Department, Technical University of Cluj-Napoca, 400614 Cluj-Napoca (Romania); Institut Neel, CNRS/Universite J. Fourier, BP166, 38042 Grenoble, Cedex 9 (France); Geoffroy, O. [Institut Neel, CNRS/Universite J. Fourier, BP166, 38042 Grenoble, Cedex 9 (France); Grenoble Electrical Engineering, University J. Fourier, BP 46, F-38402 Saint-Martin d' Heres Cedex (France); Chicinas, I. [Materials Science and Engineering Department, Technical University of Cluj-Napoca, 400614 Cluj-Napoca (Romania); Isnard, O. [Institut Neel, CNRS/Universite J. Fourier, BP166, 38042 Grenoble, Cedex 9 (France)

    2012-05-25

    Highlights: Black-Right-Pointing-Pointer Nanocrystalline soft magnetic composites were obtained. Black-Right-Pointing-Pointer The cutting frequency of the produced nanocrystalline SMC exceeds 100 kHz. Black-Right-Pointing-Pointer A long annealing at low temperature leads to an improvement of the permeability (12%). - Abstract: The preparation and characterization of the nanocrystalline soft magnetic composite core based on Supermalloy powder obtained via mechanical alloying route are presented. The AC magnetic properties of the compacts were determined in frequency range from 100 Hz to 100 kHz for flux densities of 0.05 and 0.1 T. Composite materials were obtained by covering the Supermalloy particles with a polymer binder, then compacted into toroidal shape and finally polymerized. It is found that an increase of the compacting pressure from 600 MPa to 800 MPa leads to an increase of the compacts permeability by more than 8%. Also, reducing the polymer content from 2 wt.% to 0.5 wt.% leads to an increase of the magnetic losses (at 100 kHz and 0.1 T) by 380%. The removal of the stresses induced during compaction has been accomplished by a heat treatment at 170 Degree-Sign C for 120 h. This leads to a significant increase (12%) of the relative initial permeability of the compacts.

  7. Capacitor Property and Leakage Current Mechanism of ZrO2 Thin Dielectric Films Prepared by Anodic Oxidation

    Science.gov (United States)

    Kamijyo, Masahiro; Onozuka, Tomotake; Shinkai, Satoko; Sasaki, Katsutaka; Yamane, Misao; Abe, Yoshio

    2003-07-01

    Polycrystalline ZrO2 thin film capacitors were prepared by anodizing sputter-deposited Zr films. Electrical measurements are performed for the parallel-plate anodized capacitors with an Al-ZrO2-Zr (metal-insulator-metal) structure, and a high capacitance density (0.6 μF/cm2) and a low dielectric loss of nearly 1% are obtained for a very thin-oxide capacitor anodized at 10 V. In addition, the leakage current density of this capacitor is about 1.8 × 10-8 A/cm2 at an applied voltage of 5 V. However, the leakage current is somewhat larger than that of a low-loss HfO2 capacitor. The leakage current density (J) of ZrO2 capacitors as a function of applied electric field (E) was investigated for several capacitors with different oxide thicknesses, by plotting \\ln(J) vs E1/2 curves. As a result, it is revealed that the conduction mechanism is due to the Poole-Frenkel effect, irrespective of the oxide thickness.

  8. PREPARATION,COMPLEX MECHANISM AND STRUCTURE MODEL OF METALLOPHTHALOC- YANINE-Fe3O4 NANOPARTICLES COMPOSITE

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    MPc-Fe3O4-nanoparticles composite(M=Co, Cu, Ni, Mn) have been prepared and the factors that influence their mean size have been studied. The mean size of the nanoparticles composite increase with the increase of complex temperature. The interaction of MPc with Fe3O4 nanoparticles has been studied. There are M-O covalent bonding and ionic bonding between MPc and Fe3O4 nanoparticles. The intensities of M-O bonding and ionic bonding are in vestigated .The complex mechanism of MPc with Fe3O4 nanoparticles have been studied. First, there are complex between MPc and all Fe3O4 nanoparticles. Then, Fe3O4 nanoparticles accumulate together to form the accumulators, MPc have the function of cohering Fe3O4 nanoparticles. A considerable number of MPc combine with Fe3O4 nanoparticles on the surface of the accumulators to form MPc-Fe3O4 nanoparticles composite. All the above proesses take place spontaneously. The structure model of MPc-Fe3O4 nanoparticles composite has also been investigated. Inside the MPc-Fe3O4 nanoparticles composite, Fe3O4 nanoparticles accumulate together without order, on the surface of the composite, MPc form molecular dispersion layer. The threshold of molecular dispersion layer are also investigated.

  9. Probing the doping mechanisms and electrical properties of Al, Ga and In doped ZnO prepared by spray pyrolysis

    KAUST Repository

    Maller, Robert

    2016-05-24

    The measured structural, optical and electrical properties of Al, Ga and In doped ZnO films deposited using spray pyrolysis are reported over the doping range 0.1 - 3 atomic percent (at. %). Over the entire doping series highly transparent, polycrystalline thin films are prepared. Using the AC Hall effect we probe the electronic properties of our doped films separating the impact of doping on the measured charge carrier concentrations and Hall mobility, with an emphasis on the low doping, < 1 at. %, range. In this doping range highly resistive films are formed and we highlight AC Hall as a reliable and highly reproducible technique for analysing the doping mechanism. The implementation of a simple, post-deposition heat treatment of our AZO films creates typical films with charge carrier concentrations exceeding > 1019 cm-3 and electron mobilities over 10 cm2/Vs. We describe in detail the nature of the defect chemistry and the role of intrinsic defects, particularly traps, and show that despite significant variations in dopant species and grain boundary concentrations that the defect chemistry dominates the electrical characteristics.

  10. Probing the doping mechanisms and electrical properties of Al, Ga and In doped ZnO prepared by spray pyrolysis

    KAUST Repository

    Maller, Robert; Porte, Yoann; Alshareef, Husam N.; McLachlan, Martyn

    2016-01-01

    The measured structural, optical and electrical properties of Al, Ga and In doped ZnO films deposited using spray pyrolysis are reported over the doping range 0.1 - 3 atomic percent (at. %). Over the entire doping series highly transparent, polycrystalline thin films are prepared. Using the AC Hall effect we probe the electronic properties of our doped films separating the impact of doping on the measured charge carrier concentrations and Hall mobility, with an emphasis on the low doping, < 1 at. %, range. In this doping range highly resistive films are formed and we highlight AC Hall as a reliable and highly reproducible technique for analysing the doping mechanism. The implementation of a simple, post-deposition heat treatment of our AZO films creates typical films with charge carrier concentrations exceeding > 1019 cm-3 and electron mobilities over 10 cm2/Vs. We describe in detail the nature of the defect chemistry and the role of intrinsic defects, particularly traps, and show that despite significant variations in dopant species and grain boundary concentrations that the defect chemistry dominates the electrical characteristics.

  11. Growth Mechanism and Surface Structure of Ge Nanocrystals Prepared by Thermal Annealing of Cosputtered GeSiO Ternary Precursor

    Directory of Open Access Journals (Sweden)

    Bo Zhang

    2014-01-01

    Full Text Available Ge nanocrystals (Ge-ncs embedded in a SiO2 superlattice structure were prepared by magnetron cosputtering and postdeposition annealing. The formation of spherical nanocrystals was confirmed by transmission electron microscopy and their growth process was studied by a combination of spectroscopic techniques. The crystallinity volume fraction of Ge component was found to increase with crystallite size, but its overall low values indicated a coexistence of crystalline and noncrystalline phases. A reduction of Ge-O species was observed in the superlattice during thermal annealing, accompanied by a transition from oxygen-deficient silicon oxide to silicon dioxide. A growth mechanism involving phase separation of Ge suboxides (GeOx was then proposed to explain these findings and supplement the existing growth models for Ge-ncs in SiO2 films. Further analysis of the bonding structure of Ge atoms suggested that Ge-ncs are likely to have a core-shell structure with an amorphous-like surface layer, which is composed of GeSiO ternary complex. The surface layer thickness was extracted to be a few angstroms and equivalent to several atomic layer thicknesses.

  12. An organic-inorganic hybrid coagulant containing Al, Zn and Fe (HOAZF: preparation, efficiency and mechanism of removing organic phosphorus

    Directory of Open Access Journals (Sweden)

    Y. Fu

    2018-04-01

    Full Text Available A polymeric-Al-Zn-Fe (PAZF coagulant showing high removal of pollutants has been successfully developed using a galvanized slag in earlier works, but it gave less elimination of phosphorus. To improve phosphorus removal, a hybrid organic-Al-Zn-Fe (HOAZF coagulant was prepared using PAZF and polyacrylamide (PAM as an organic additive, and then was characterized by scanning electron microscopy (SEM, infrared spectroscopy (IR, X-ray diffraction (XRD, and Zeta potential, respectively. Removing efficiency and mechanism of organophosphorus by HOAZF was probed using jar tests in treating a simulated pesticide wastewater containing dichlorvos (DDVP, compared to that by PAZF and polyaluminum chloride. The results displayed that HOAZF having relative lower Zeta potential (compared to PAZF exhibited complex surface morphology composited by Al, Zn and Fe and PAM, forming some new crystalline and amorphous substances different from that in PAZF. HOAZF gave higher removal of organophosphorus and far lower dosage than PAZF, and also posed a suitable wider pH range (pH = 7–12 for HOAZF and 10–11 for PAZF, respectively and suitable wider organophosphorus level range than PAZF. Removing organophosphorus by HOAZF was a simultaneous complex process involving a non-phase transfer of adsorption/bridging/sweeping and a phase transfer of chemical precipitation.

  13. Preparation and mechanical properties of liquid-phase sinterd silicon carbide; Herstellung und mechanische Eigenschaften von fluessigphasengesintertem Siliziumkarbid

    Energy Technology Data Exchange (ETDEWEB)

    Wiedmann, I.

    1998-12-01

    Liquid-phase sintered silicon carbide ceramics, LPS-SiC, were prepared, and the influence of structure and chemical secondary phase composition on the mechanical properties was investigated in order to identify LPS-SiC materials which can be produced reproducibly and with low loss of mass by simple techniques, i.e. without powder bed or encapsulation. Their profile of characteristics should be superior to conventional solid-phase sintered SiC and should be comparable with liquid-phase sintered silicon nitride ceramics. [Deutsch] In der vorliegenden Arbeit wurden fluessigphasengesinterte Siliziumkarbid-Keramiken, LPS-SiC, hergestellt und der Einfluss der Gefuegeausbildung und der chemischen Sekundaerphasenzusammensetzung auf die mechanischen Eigenschaften untersucht. Ziel war es, LPS-SiC-Materialien zu identifizieren, die ohne besonderen Vorkehrungen wie Pulverbett oder Einkapselung reproduzierbar und mit geringem Masseverlust hergestellt werden koennen. Das Eigenschaftsprofil sollte deutlich ueber dem von konventionell festphasengesintertem SiC liegen und vergleichbar zu fluessigphasengesinterten Siliziumnitrid-Keramiken sein. (orig.)

  14. The exploration of endocytic mechanisms of PLA-PEG nanoparticles prepared by coaxialtri-capillary electrospray-template removal method.

    Science.gov (United States)

    Chen, Jiaming; Cao, Lihua; Cui, Yuecheng; Tu, Kehua; Wang, Hongjun; Wang, Li-Qun

    2018-01-01

    The nano-sized poly(lactic acid)-poly(ethylene glycol) (PLA-PEG) particles with core-shell structure were efficiently prepared by using coaxial tri-capillary electrospray-template removal method. The cellular uptake mechanism, intracellular distribution and exocytosis in A549 cell model of electrosprayed PLA-PEG nanoparticles were systemically studied. The drug release behavior of electrosprayed PLA-PEG nanoparticles were also investigated. Our results showed that PLA-PEG nanoparticles can be endocytosed quickly by A549 cells. The cellular uptake of PLA-PEG nanoparticles was an energy dependent endocytosis process. Caveolae-mediated endocytosis was only one of endocytosis pathways in A549 cells for PLA-PEG nanoparticles, while clathrin mediated endocytosis was not involved in the endocytosis process. The endocytosed PLA-PEG nanoparticles enriched in the head of A549 cells and only a small amount of them was transported into lysosome after 24h incubation. These findings provided insights into the application of electrosprayed PLA-PEG nanoparticles in nano drug delivery field. Copyright © 2017 Elsevier B.V. All rights reserved.

  15. Evaluation of the surface roughness of three heat-cured acrylic denture base resins with different conventional lathe polishing techniques: A comparative study.

    Science.gov (United States)

    Rao, Duggineni Chalapathi; Kalavathy, N; Mohammad, H S; Hariprasad, A; Kumar, C Ravi

    2015-01-01

    Surface roughness promotes adhesion and colonization of denture plaque. Therefore, it is important to know the effects of polishing and finishing on the surface roughness of various acrylic resin materials. To evaluate and compare the effects of different conventional lathe polishing techniques on heat cured acrylic resins in producing surface roughness. Three different commercially available heat-cured acrylic resin materials namely DPI, Meliodent and Trevalon Hi were selected. 30 Specimens of each acrylic material (30 x 3 = 90, 10 x 60 x 2mm) were prepared and divided into 5 groups, each group consisted of 6 Nos. of specimens per material(6x3=18) and were grouped as Group A(unfinished), Group B (finished), Group C (Polishing Paste), Group D (Polishing Cake) and Group E (Pumice and Gold rouge). The resulted surface roughness (μm) was measured using Perthometer and observed under Scanning Electron Microscope. The values obtained were subjected statistical analyses. Among the materials tested, better results were obtained with Trevalon Hi followed by Meliodent and DPI. Among the polishing methods used, superior results were obtained with universal polishing paste followed by polishing cake; Pumice and Gold rouge. Although Pumice and Gold rouge values produced greater roughness value, they were well within the threshold value of 0.2 mm.

  16. Measurement of surface roughness changes of unpolished and polished enamel following erosion.

    Directory of Open Access Journals (Sweden)

    Francesca Mullan

    Full Text Available To determine if Sa roughness data from measuring one central location of unpolished and polished enamel were representative of the overall surfaces before and after erosion.Twenty human enamel sections (4x4 mm were embedded in bis-acryl composite and randomised to either a native or polishing enamel preparation protocol. Enamel samples were subjected to an acid challenge (15 minutes 100 mL orange juice, pH 3.2, titratable acidity 41.3mmol OH/L, 62.5 rpm agitation, repeated for three cycles. Median (IQR surface roughness [Sa] was measured at baseline and after erosion from both a centralised cluster and four peripheral clusters. Within each cluster, five smaller areas (0.04 mm2 provided the Sa roughness data.For both unpolished and polished enamel samples there were no significant differences between measuring one central cluster or four peripheral clusters, before and after erosion. For unpolished enamel the single central cluster had a median (IQR Sa roughness of 1.45 (2.58 μm and the four peripheral clusters had a median (IQR of 1.32 (4.86 μm before erosion; after erosion there were statistically significant reductions to 0.38 (0.35 μm and 0.34 (0.49 μm respectively (p<0.0001. Polished enamel had a median (IQR Sa roughness 0.04 (0.17 μm for the single central cluster and 0.05 (0.15 μm for the four peripheral clusters which statistically significantly increased after erosion to 0.27 (0.08 μm for both (p<0.0001.Measuring one central cluster of unpolished and polished enamel was representative of the overall enamel surface roughness, before and after erosion.

  17. Effect of finishing and polishing on color stability of a nanofilled resin immersed in different media

    Directory of Open Access Journals (Sweden)

    Ana Luísa Botta Martins de OLIVEIRA

    Full Text Available OBJECTIVE: The purpose of this study was to evaluate the effect of finishing and polishing on color stability of a nanofilled composite resin (Filtek Z350 XT according to different immersion media.MATERIAL AND METHOD: Composite disks (10 mm diameter, 2 mm thickness were prepared for each group (n = 6 using a stainless steel mold. The groups were divided according to the presence or absence of finishing and polishing procedure and immersion media (artificial saliva, artificial juice- KAPO(r Coca-Cola(rflavors: pineapple, orange, strawberry and grape. The finishing and polishing procedures were performed using Super -Snap(r disks. The specimens were stored in artificial saliva for 24 hours (baseline and were analyzed using a color spectrophotometer by CIELab system. Then, they were immersed in different media for 5 minutes, 3 times a day, every 4 hours during 60 days. They were stored in artificial saliva at 37 ± 1°C during the immersion intervals. After this time, new measure of color was performed. The data were analyzed using Kruskall-Wallis test and Mann- Whitney test. The significance level was 5%.RESULT: The results showed that the finishing/polishing not significantly influence the color stability of resin composite (p > 0.05. There was no statistically significant difference in the color stability of the studied resin after immersion in different media (p > 0.05.CONCLUSION: The finishing and polishing procedures and the immersion media did not have influence on color stability of nanofilled resin Filtek Z350 XT.

  18. Strategies for sustainable development of the Polish electric power system

    International Nuclear Information System (INIS)

    Janiczek, R.

    1996-01-01

    The key features of sustainable development of the Polish electric power industry are discussed. Priorities and limitations for changes and power demand forecasts are described. Results of least-cost planning for existing power plants' modernization and generation expansion with environmental impacts are presented. The least-cost strategy is given by the optimal upgrades of older plants until year 2002 and by expansion of gas-fired units. The limited availability of gas after 2010 will lead to the construction of new coal-fired plants. For the next planning process, an integrated resource planning methodology is proposed, which includes dynamic optimization of supply and demand side options. Innovative mechanisms are shown to overcome barriers of development like long-terms contracts and decentralization of the power system planning process. (author)

  19. Friction Properties of Polished Cvd Diamond Films Sliding against Different Metals

    Science.gov (United States)

    Lin, Zichao; Sun, Fanghong; Shen, Bin

    2016-11-01

    Owing to their excellent mechanical and tribological properties, like the well-known extreme hardness, low coefficient of friction and high chemical inertness, chemical vapor deposition (CVD) diamond films have found applications as a hard coating for drawing dies. The surface roughness of the diamond films is one of the most important attributes to the drawing dies. In this paper, the effects of different surface roughnesses on the friction properties of diamond films have been experimentally studied. Diamond films were fabricated using hot filament CVD. The WC-Co (Co 6wt.%) drawing dies were used as substrates. A gas mixture of acetone and hydrogen gas was used as the feedstock gas. The CVD diamond films were polished using mechanical polishing. Polished diamond films with three different surface roughnesses, as well as the unpolished diamond film, were fabricated in order to study the tribological performance between the CVD diamond films and different metals with oil lubrication. The unpolished and polished CVD diamond films are characterized with scanning electron microscope (SEM), atomic force microscope (AFM), surface profilometer, Raman spectrum and X-ray diffraction (XRD). The friction examinations were carried out by using a ball-on-plate type reciprocating friction tester. Low carbide steel, stainless steel, copper and aluminum materials were used as counterpart balls. Based on this study, the results presented the friction coefficients between the polished CVD films and different metals. The friction tests demonstrate that the smooth surface finish of CVD diamond films is beneficial for reducing their friction coefficients. The diamond films exhibit low friction coefficients when slid against the stainless steel balls and low carbide steel ball, lower than that slid against copper ball and aluminum ball, attributed to the higher ductility of copper and aluminum causing larger amount of wear debris adhering to the sliding interface and higher adhesive

  20. Polish Phoneme Statistics Obtained On Large Set Of Written Texts

    Directory of Open Access Journals (Sweden)

    Bartosz Ziółko

    2009-01-01

    Full Text Available The phonetical statistics were collected from several Polish corpora. The paper is a summaryof the data which are phoneme n-grams and some phenomena in the statistics. Triphonestatistics apply context-dependent speech units which have an important role in speech recognitionsystems and were never calculated for a large set of Polish written texts. The standardphonetic alphabet for Polish, SAMPA, and methods of providing phonetic transcriptions are described.

  1. Polish Qualitative Sociology: The General Features and Development

    OpenAIRE

    Konecki, Krzysztof Tomasz; Kacperczyk, Anna; Marciniak, Łukasz

    2005-01-01

    Forum Qualitative Sozialforschung / Forum: Qualitative Social Research,2005, 6(3) The article explores the development of Polish qualitative sociology in Poland by presenting its main intellectual routes and some of the general features of Polish sociology. Romanticism and inductionmethod are crucial elements for the development of this discipline in Poland and contribute to its. unigueness. The role of Florian Znaniecki in creating the Polish qualitative sociology is also underlined.

  2. The Effect of Prophylactic Polishing Pastes on Surface Roughness of Indirect Restorative Materials

    Directory of Open Access Journals (Sweden)

    Esra Can Say

    2014-01-01

    Full Text Available The purpose of this study was to evaluate the influence of prophylactic polishing pastes (PPP; Detartrine (DT, Topex (TP on surface roughness (Ra of indirect composites (IRC; Tescera (TES, Gradia (GRD, and Estenia C&B (EST, a glass ceramic (Empress 2 layering (E2, and a leucite reinforced glass ceramic (Empress Esthetic (EE with two different (glazed (G; polished (P surface preparations. A total of 90 IRC and 120 ceramic discs, 8 mm in diameter and 2 mm thick, were prepared. E2 and EE specimens were randomly divided into two groups (n=30. One group was glazed (GE2; GEE, while the other group was polished (PE2; PEE the same as the IRCs. The specimens in each group were subsequently divided into three subgroups: control (C, DT, and TP. Ra (μm was evaluated with a profilometer. Data were analyzed by Kruskal Wallis, followed by the Dunn's multiple comparison tests P0.05. PE2 and PEE were not affected by DT or TP P>0.05, while GE2 and GEE exhibited significant roughening after TP P<0.05. Surface roughness of IRCs and glazed ceramics can be affected by PPP applications.

  3. Food additives used in meat processing according to the Polish and European Union legislation.

    Science.gov (United States)

    Uradziński, J; Weiner, M

    2003-01-01

    This paper presents the legal regulations related to the use of food additives in meat production in Poland and the European Union. The Polish legal definition of food additives is given as well as the classification of permitted food additives added to food and stimulants by their technological function. In addition, a definition of processing aids in the food industry is included. It shows that Polish legislation includes food additives used to ensure or improve food nutritional value, whereas in the EU legislation, these substances are not included in the list of food additives. Moreover, the Council Directives include food additive specific purity criteria, whereas the Polish regulations do not mention the legal regulations of this issue in practice. The European Union use mechanisms and procedures for the introduction of new food additives into internal markets as well as controlling the circulation of additives. The Polish legislation in practice, however, does not determine approval or methods for the introduction of new food additives to the market. Legal regulations on the monitoring of food additives no exist.

  4. New ion exchange resin designs and regeneration procedures yield improved performance for various condensate polishing applications

    International Nuclear Information System (INIS)

    Najmy, S.W.

    2002-01-01

    Condensate polishing is an application with many different design and operational aspects. The past decade has brought new challenges for improved water quality with respect to both soluble and insoluble contaminants. Nonetheless, the endeavors to understand the compositional complexities of the ion exchange resin bead and the convoluted dynamics of ion exchange chemistry and chemical engineering mechanisms occurring within the mixed bed condensate polisher have brought new ideas and expectations for ion exchange resin in deep-bed condensate polishers than ever before. The new products and procedures presented here are a collaboration of a great deal of effort on the part of researchers, consultants, system engineers, station chemists, lab technicians and others. The studies discussed in this paper unequivocally demonstrate the merits of: 1. A specially designed cation resin to achieve greater than 95% insoluble iron removal efficiency, 2. A less-separable mixed resin for improved control of reactor water sulfate in BWR primary cycles, 3. Applying increased levels of regeneration chemicals and retrofitting the service vessels with re-mixing capability to improve the operation of deep-bed condensate polishers in PWR secondary cycles. (authors)

  5. Study of Pneumatic Servo Loading System in Double-Sided Polishing

    International Nuclear Information System (INIS)

    Qian, N; Ruan, J; Li, W

    2006-01-01

    The precise double-sided polishing process is one of the main methods to get the ultra-smooth surface of workpiece. In double-sided polishing machine, a loading system is required to be able to precisely control the load superimposed on the workpiece, while the polishing is being carried out. A pneumatic servo loading system is proposed for this purpose. In the pneumatic servo system, the servo valve, which acts both the electrical to mechanical converter and the power amplifier, has a substantial influence on the performance of the loading system. Therefore a specially designed pneumatic digital servo valve is applied in the control system. In this paper, the construction of the pneumatic servo loading system in double-sided polishing machine and control strategy associated with the digital servo valve are first addressed. The mathematical model of the system established and the hardware of the pneumatic servo system is designed. Finally, the experiments are carried out by measuring the practical load on the workpiece and the quality of the surface finish. It is demonstrated that the error rate of load is less than 5% and a super-smooth surface of silicon wafer with roughness Ra 0.401 nm can be obtained

  6. Assessing operability of a novel polisher arrangement using MMS

    International Nuclear Information System (INIS)

    Shor, S.W.W.

    1987-01-01

    A condensate polisher is intended to remove both particulate matter and ionic material from the condensate. Condensate polishers have normally been placed directly in the condensate system downstream of the condensate pumps. This inline location has certain disadvantages. These disadvantages are discussed. Placing the polisher in a sidestream location, where water is removed from the condensate system, pumped through the polisher, and then returned to the condensate system provides a solution to these disadvantages. Several possible types of sidestream installations is described. This has a polisher taking unpolished condensate from one compartment from one compartment of a divided hotwell in a specially modified condenser and returning polished condensate to the other compartment. The polisher is supplied by its own dedicated pumps, which have a head requirement sufficient only to overcome the pressure drop through the polisher circuit at a flow rate of 110% of maximum condensate flow. This concept is very attractive but has not yet been tested even though it is being installed in several new units. A simulation was, therefore, performed using MMS to provide confidence that this particular sidestream polisher arrangement was operationally viable

  7. SEM Evaluation and Comparision of Marginal Integrity in Glass-Ionomer and Copmposite Class Restoratins With Immediate or Delay Polishing

    Directory of Open Access Journals (Sweden)

    Ranjbar Omidi B

    2011-12-01

    Full Text Available Background and Aims: Marginal seal in class V cavities and determining the best restorative material to decrease microleakage is of great importance in operative dentistry. The aim of this study was to evaluate the effect of polishing time on the microleakage of three types of tooth-colored restorative materials in class V cavity preparations and to assess the marginal integrity of these materials using scanning electron microscope (SEM.Materials and Methods: In this in vitro study, class V cavity preparations were made on the buccal and lingual surfaces of 30 bovine incisors (60 cavities. The specimens were divided into three groups each containing 10 teeth (20 cavities: group 1, Filtek Z350 (nanocomposite; group 2, Fuji IX/G Coat Plus (CGIC; and group 3, Fuji II LC (RMGI. In each group, half of the specimens (n = 20 were finished/polished immediately and the rest of them were finished/polished after 24 hours. All the specimens were thermocycled for 2000 cycles (5-50 °C. Epoxy resin replicas of 12 specimens (2 restorations in each subgroup were evaluated using SEM and the interfacial gaps were measured. Finally, the teeth were immersed in 0.5% basic fuchsin dye for 24 hours at room temperature, sectioned and observed under stereomicroscope. The data were analyzed using Kruskal-Wallis and Mann-Whitney U tests and the comparison between incisal and cervical microleakage was made with Wilcoxon test.Results: Incisal and cervical microleakage were not affected by polishing time in none of the three restorative materials (P>0.05. Cervical microleakage only in Fuji IX with immediate polishing was significantly higher than incisal microleakage (P0.05.Conclusion: Immediate polishing is recommended in tooth-colored class V restorations.

  8. Origin of high oxide to nitride polishing selectivity of ceria-based slurry in the presence of picolinic acid

    International Nuclear Information System (INIS)

    Wang Liang-Yong; Liu Bo; Song Zhi-Tang; Liu Wei-Li; Feng Song-Lin; David Huang; Babu, S.V

    2011-01-01

    We report on the investigation of the origin of high oxide to nitride polishing selectivity of ceria-based slurry in the presence of picolinic acid. The oxide to nitride removal selectivity of the ceria slurry with picolinic acid is as high as 76.6 in the chemical mechanical polishing. By using zeta potential analyzer, particle size analyzer, horizon profilometer, thermogravimetric analysis and Fourier transform infrared spectroscopy, the pre- and the post-polished wafer surfaces as well as the pre- and the post-used ceria-based slurries are compared. Possible mechanism of high oxide to nitride selectivity with using ceria-based slurry with picolinic acid is discussed. (interdisciplinary physics and related areas of science and technology)

  9. Origin of high oxide to nitride polishing selectivity of ceria-based slurry in the presence of picolinic acid

    Institute of Scientific and Technical Information of China (English)

    Wang Liang-Yong; Liu Bo; Song Zhi-Tang; Liu Wei-Li; Feng Song-Lin; David Huang; S.V Babu

    2011-01-01

    We report on the investigation of the origin of high oxide to nitride polishing selectivity of ceria-based slurry in the presence of picolinic acid. The oxide to nitride removal selectivity of the ceria slurry with picolinic acid is as high as 76.6 in the chemical mechanical polishing. By using zeta potential analyzer, particle size analyzer, horizon profilometer, thermogravimetric analysis and Fourier transform infrared spectroscopy, the pre-and the post-polished wafer surfaces as well as the pre-and the post-used ceria-based slurries are compared. Possible mechanism of high oxide to nitride selectivity with using ceria-based slurry with picolinic acid is discussed.

  10. Resilient Amorphous Networks Prepared by Photo-Crosslinking High-Molecular-Weight D,L-Lactide and Trimethylene Carbonate Macromers: Mechanical Properties and Shape-Memory Behavior

    NARCIS (Netherlands)

    Sharifi, Shahriar; Grijpma, Dirk W.

    2012-01-01

    Tough networks are prepared by photo-crosslinking high-molecular-weight DLLA and TMC macromers. These amorphous networks exhibit tunable thermal and mechanical properties and have excellent shape-memory features. Variation of the monomer ratio allows adjustment of Tg between approximately −13 and

  11. Benefits and costs of IFRS implementation in the opinion of Polish certified auditors

    Directory of Open Access Journals (Sweden)

    Anna Karmańska

    2017-12-01

    Full Text Available The article presents the results of a survey conducted among a carefully selected group of Polish certified auditors. The purpose of the study was to determine whether auditors, during the audit of financial state- ments, perceive certain costs and benefits resulting from the fact that the audited statements were pre- pared in accordance with IFRS. This survey was undertaken to demonstrate that the cost-benefit analysis of IFRS, after more than a decade of their use in Polish practice, could provide important observations for future legislative changes in this area. The study shows that, thanks to the implementation of IFRSs, auditors gain the benefit of lower audit workloads. At the same time, however, they identify six reasons why the audit process is prolonged, requiring special organization, prior special preparation and, as a result, higher auditing costs

  12. Technology of Polish copper ore beneficiation – perspectives from the past experience

    Directory of Open Access Journals (Sweden)

    Wieniewski Andrzej

    2016-01-01

    Full Text Available The paper describes the main types of existing copper deposits in the world and the most common enrichment technologies. The characteristic elements of the current flowsheet of the Polish ore beneficiation were discussed together with the reasons for using them. The paper presents a perspective flowsheet based on more than 50-years of experience in beneficiation of Polish copper ore. The main elements of proposed technology are: leaving in justified cases the division of ore into fractions of increased sandstone and carbonate ores content, flotation in the milling circuit as part of the effective preparation of the ore to rougher flotation, intensive rougher flotation, classic cleaning system, processing of the middlings with grinding system in new type mills, classification and flotation with outlet of final tailings.

  13. Polish country study to address climate change: Strategies of the GHG`s emission reduction and adaptation of the Polish economy to the changed climate. Final report

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1996-01-01

    The Polish Country Study Project was initiated in 1992 as a result of the US Country Study Initiative whose objective was to grant the countries -- signatories of the United Nations` Framework Convention on Climate Change -- assistance that will allow them to fulfill their obligations in terms of greenhouse gases (GHG`s) inventory, preparation of strategies for the reduction of their emission, and adapting their economies to the changed climatic conditions. In February 1993, in reply to the offer from the United States Government, the Polish Government expressed interest in participation in this program. The Study proposal, prepared by the Ministry of Environmental Protection, Natural Resources and Forestry was presented to the US partner. The program proposal assumed implementation of sixteen elements of the study, encompassing elaboration of scenarios for the strategy of mission reduction in energy sector, industry, municipal management, road transport, forestry, and agriculture, as well as adaptations to be introduced in agriculture, forestry, water management, and coastal management. The entire concept was incorporated in macroeconomic strategy scenarios. A complementary element was the elaboration of a proposal for economic and legal instruments to implement the proposed strategies. An additional element was proposed, namely the preparation of a scenario of adapting the society to the expected climate changes.

  14. Slower nicotine metabolism among postmenopausal Polish smokers.

    Science.gov (United States)

    Kosmider, Leon; Delijewski, Marcin; Koszowski, Bartosz; Sobczak, Andrzej; Benowitz, Neal L; Goniewicz, Maciej L

    2018-06-01

    A non-invasive phenotypic indicator of the rate of nicotine metabolism is nicotine metabolite ratio (NMR) defined as a ratio of two major metabolites of nicotine - trans-3'-hydroxycotinine/cotinine. The rate of nicotine metabolism has important clinical implications for the likelihood of successful quitting with nicotine replacement therapy (NRT). We conducted a study to measure NMR among Polish smokers. In a cross-sectional study of 180 daily cigarette smokers (42% men; average age 34.6±13.0), we collected spot urine samples and measured trans-3'-hydroxycotinine (3-HC) and cotinine levels with LC-MS/MS method. We calculated NMR (molar ratio) and analyzed variations in NMR among groups of smokers. In the whole study group, an average NMR was 4.8 (IQR 3.4-7.3). The group of women below 51 years had significantly greater NMR compared to the rest of the population (6.4; IQR 4.1-8.8 vs. 4.3; IQR 2.8-6.4). No differences were found among group ages of male smokers. This is a first study to describe variations in nicotine metabolism among Polish smokers. Our findings indicate that young women metabolize nicotine faster than the rest of population. This finding is consistent with the known effects of estrogen to induce CYP2A6 activity. Young women may require higher doses of NRT or non-nicotine medications for most effective smoking cessation treatment. Copyright © 2017 Institute of Pharmacology, Polish Academy of Sciences. Published by Elsevier B.V. All rights reserved.

  15. Plasma electrolytic polishing of metalized carbon fibers

    Directory of Open Access Journals (Sweden)

    Falko Böttger-Hiller

    2016-02-01

    Full Text Available Efficient lightweight structures require intelligent materials that meet versatile functions. Especially, carbon-fiber-reinforced polymers (CFRPs are gaining relevance. Their increasing use aims at reducing energy consumption in many applications. CFRPs are generally very light in weight, while at the same time being extremely stiff and strong (specific strength: CFRPs: 1.3 Nm kg–1, steel: 0.27 Nm kg–1; specific stiffness: CFRPs: 100 Nm kg–1, steel: 25 Nm kg–1. To increase performance and especially functionality of CFRPs, the integration of microelectronic components into CFRP parts is aspired. The functionalization by sensors, actuators and electronics can enable a high lightweight factor and a new level of failure-safety. The integration of microelectronic components for this purpose requires a working procedure to provide electrical contacts for a reliable connection to energy supply and data interfaces. To overcome this challenge, metalized carbon fibers are used. Metalized fibers are, similar to the usual reinforcing fibers, able to be soldered and therefore easy to incorporate into CFRPs. Unfortunately, metalized fibers have to be pre-treated by flux-agents. Until now, there is no flux which is suitable for mass production without destroying the polymer of the CFRP. The process of plasma electrolytic polishing (PeP could be an option, but is so far not available for copper. Thus, in this study, plasma electrolytic polishing is transferred to copper and its alloys. To achieve this, electrolytic parameters as well as the electrical setup are adapted. It can be observed that the gloss and roughness can be adjusted by means of this procedure. Finally, plasma electrolytic polishing is used to treat thin copper layers on carbon fibers.

  16. Comparison of Swelling and Mechanical Analysis for the Determination of Crosslink Density of Acrylamide Based Hydrogels Prepared by Ionizing Radiation

    International Nuclear Information System (INIS)

    Sen, M.

    2006-01-01

    One of the basic parameters that describes the structure of a hydrogel network is the molecular weight between cross-links or cross-link density of highly swollen network. Several theories have been proposed to calculate the average molecular weight between cross-links. In the highly swollen state, the constrained junction theory indicates that a real network exhibits properties closer to those of the phantom network model and molecular weight between cross-links can be calculated easily by using swelling and polymer-solvent based parameters such as molar volume of the swelling agent, polymer-solvent interaction parameter, functionality, specific volume of the polymer and polymer volume fraction in the relaxed state. Molecular weight between cross-links (M c a ver.) and effective cross-linking density (V e ) of a hydrogel can also be determined from shear modulus data obtained from compression tests. Our previous studies indicated that simple compression analyses and equations derived from Phantom network theory can be used for the determination of effective cross-link density of hydrogels without needing some polymer-solvent based parameters as in the case of swelling based determinations. The M c a ver. and V e values calculated from mechanical tests were found to be very close to the values obtained from swelling experiments. Slight differences observed were attributed to the uncertainty on the value of the χ parameter used in the expression related to swelling data. In this study the uncertainty in the polymer based parameter χ on the M c a ver. was discussed. Poly(acrylamide/methacrylamide) P(AAm/MAAm) and Poly(acrylamide/hydroxyethylmeth acrylate) P(AAm/HEMA) hydrogels were prepared by gamma rays and used as model hydrogel systems. The uniaxial compression was applied to cylindrical samples using the Universal Testing Instrument in the swollen form at pH 7. Stress-strain curves of hydrogels were evaluated to calculate the shear modulus values. The M c a ver

  17. An Unbiased View of the History of Polish Medical Physics by a Senior Polish Medical Physicist

    International Nuclear Information System (INIS)

    Chomicki, O. A.

    2008-01-01

    Here is a story told by Maria Sklodowska-Curie at the meeting of the International Committee of Intellectual Cooperation in 1921: 'In a free literary competition on the role and importance of elephants the Englishman's story was 'My adventures while shooting elephants in South Africa', the Frenchman was more concerned with 'The sexual and erotic life of elephants', while the Polish approach was invariably 'The elephant versus Poland's national independence', which seemed quite understandable in the light of over 120 years when Poland was partitioned and lost its independence. Since then this saying has become proverbial and came to express the unmistakably Polish tendency to see everything in terms of Polish interests. In my remarks and reminiscences on the history of the Polish Society of Medical Physics you will quickly recognize the same tendency. First, I will, among other things, try to open some old cupboards to 'produce good [things] from the store of good' (Matthew 12:35), especially concerning the first few years of the activity in medical physics in Poland, and second, I will draw some conclusions and/or offer suggestions based on what a senior medical physicist has seen for more than 50 years of his activity in this field. (author)

  18. New technology and tool prepared for communication against storm surges.

    Science.gov (United States)

    Letkiewicz, Beata

    2010-05-01

    The aim of the presentation is description of the new technology and tool prepared for communication, information and issue of warnings against storm surges. The Maritime Branch of the Institute of Meteorology and Water Management is responsible for preparing the forecast as warning, where the end users are Government Officials and Public. The Maritime Branch carry out the project "Strengthening the administrative capacity in order to improve the management of Polish coastal zone environment" (supported by a grant from Norway through the Norwegian Financial Mechanism). The expected final result of the project is web site www.baltyk.pogodynka.pl. One of the activities of the project is - set up of information website www.baltyk.pogodynka.pl, giving public access to the complied data. Information on web site: - meta data - marine data (on-line measurement: sea level, water temperature, salinity, oxygen concentration); - data bases of mathematical model outputs - forecast data (sea level, currents); - ice conditions of the Baltic Sea, - instructions, information materials with information of polish coastal zone. The aim of set up of the portal is development of communication between users of the system, exchange of the knowledge of marine environment and natural hazards such as storm surges, improving the ability of the region in the scope of the data management about the sea environment and the coastal zone.

  19. METALLOGRAPHIC SAMPLE PREPARATION STATION-CONSTRUCTIVE CONCEPT

    Directory of Open Access Journals (Sweden)

    AVRAM Florin Timotei

    2016-11-01

    Full Text Available In this paper we propose to present the issues involved in the case of the constructive conception of a station for metallographic sample preparation. This station is destined for laboratory work. The metallographic station is composed of a robot ABB IRB1600, a metallographic microscope, a gripping device, a manipulator, a laboratory grinding and polishing machine. The robot will be used for manipulation of the sample preparation and the manipulator take the sample preparation for processing.

  20. Dissolved air flotation of polishing wastewater from semiconductor manufacturer.

    Science.gov (United States)

    Liu, J C; Lien, C Y

    2006-01-01

    The feasibility of the dissolved air flotation (DAF) process in treating chemical mechanical polishing (CMP) wastewater was evaluated in this study. Wastewater from a local semiconductor manufacturer was sampled and characterised. Nano-sized silica (77.6 nm) with turbidity of 130 +/- 3 NTU was found in the slightly alkaline wastewater with traces of other pollutants. Experimental results indicated removal efficiency of particles, measured as suspended particle or turbidity, increased with increasing concentration of cationic collector cetyltrimethyl ammonium bromide (CTAB). When CTAB concentration was 30 mg/L, pH of 6.5 +/- 0.1 and recycle ratio of 30%, very effective removal of particles (> 98%) was observed in saturation pressure range of 4 to 6 kg/cm2, and the reaction proceeded faster under higher pressure. Similarly, the reaction was faster under the higher recycle ratio, while final removal efficiency improved slightly as the recycle ratio increased from 20 to 40%. An insignificant effect of pH on treatment efficiency was found as pH varied from 4.5 to 8.5. The presence of activator, Al3+ and Fe3+, enhanced the system performance. It is proposed that CTAB adsorbs on silica particles in polishing wastewater through electrostatic interaction and makes particles more hydrophobic. The increase in hydrophobicity results in more effective bubble-particle collisions. In addition, flocculation of silica particles through bridging effect of collector was found; it is believed that flocculation of particles also contributed to flotation. Better attachment between gas bubble and solid, higher buoyancy and higher air to solid ratio all lead to effective flotation.

  1. Immigrant families in historical perspective: the experiences of Polish pioneers in Winnipeg, 1896-1919

    Directory of Open Access Journals (Sweden)

    ŁUKASZ ALBAŃSKI

    2017-10-01

    Full Text Available This paper focuses on an early Polish family life in Winnipeg. The family often served as a mechanism to reduce a sense of dislocation and to facilitate immigrants' adaptation. The family was also the primary economic unit. The family relations were affected by gender. Both immigrant men and women found themselves reconsidering traditional roles. Somehow immigration tested their family roles in newways.

  2. Farmers' pensions and the Polish economic crisis.

    Science.gov (United States)

    Simanis, J G

    1983-04-01

    The Polish Government, in 1977, inaugurated a new pension program that made old-age and invalidity benefits available for the first time to most farmers in that country. The evolution and eventual failure of that program were closely intertwined with a growing national economic crisis, manifested in widespread popular unrest and culminating in emergence of the Solidarity movement. The farmers' pension program was originally presented as both a social security measure and a vehicle for improving agricultural efficiency. The economic situation was expected to benefit as farms of older owners were passed to younger, presumably more efficient, successors, with the state sometimes acting as intermediary. A further step to bind the social security concept to agricultural efficiency came through relating the pension amount to the quantity of produce the individual farmer sold to the state over a number of years. The failure of these provisions and other unpopular features of the new program was aggravated by inflation and continuing deterioration of the Polish economy.

  3. The effects of crosslinkers on physical, mechanical, and cytotoxic properties of gelatin sponge prepared via in-situ gas foaming method as a tissue engineering scaffold.

    Science.gov (United States)

    Poursamar, S Ali; Lehner, Alexander N; Azami, Mahmoud; Ebrahimi-Barough, Somayeh; Samadikuchaksaraei, Ali; Antunes, A P M

    2016-06-01

    In this study porous gelatin scaffolds were prepared using in-situ gas foaming, and four crosslinking agents were used to determine a biocompatible and effective crosslinker that is suitable for such a method. Crosslinkers used in this study included: hexamethylene diisocyanate (HMDI), poly(ethylene glycol) diglycidyl ether (epoxy), glutaraldehyde (GTA), and genipin. The prepared porous structures were analyzed using Fourier Transform Infrared Spectroscopy (FT-IR), thermal and mechanical analysis as well as water absorption analysis. The microstructures of the prepared samples were analyzed using Scanning Electron Microscopy (SEM). The effects of the crosslinking agents were studied on the cytotoxicity of the porous structure indirectly using MTT analysis. The affinity of L929 mouse fibroblast cells for attachment on the scaffold surfaces was investigated by direct cell seeding and DAPI-staining technique. It was shown that while all of the studied crosslinking agents were capable of stabilizing prepared gelatin scaffolds, there are noticeable differences among physical and mechanical properties of samples based on the crosslinker type. Epoxy-crosslinked scaffolds showed a higher capacity for water absorption and more uniform microstructures than the rest of crosslinked samples, whereas genipin and GTA-crosslinked scaffolds demonstrated higher mechanical strength. Cytotoxicity analysis showed the superior biocompatibility of the naturally occurring genipin in comparison with other synthetic crosslinking agents, in particular relative to GTA-crosslinked samples. Copyright © 2016 Elsevier B.V. All rights reserved.

  4. The Czechoslovak-Polish Club in Brno (1925–1939)

    Czech Academy of Sciences Publication Activity Database

    Baron, Roman

    2011-01-01

    Roč. 3, č. 1 (2011), s. 43-64 ISSN 1803-6546 Institutional research plan: CEZ:AV0Z80150510 Keywords : Czechoslovak-Polish solidarity * Czechoslovak-Polish relations * Brno * associations * Interwar Period Subject RIV: AB - History

  5. Phonematic translation of Polish texts by the neural network

    International Nuclear Information System (INIS)

    Bielecki, A.; Podolak, I.T.; Wosiek, J.; Majkut, E.

    1996-01-01

    Using the back propagation algorithm, we have trained the feed forward neural network to pronounce Polish language, more precisely to translate Polish text into its phonematic counterpart. Depending on the input coding and network architecture, 88%-95% translation efficiency was achieved. (author)

  6. Etymology in the Polish Academy of Sciences Great Dictionary of ...

    African Journals Online (AJOL)

    The article offers an insight into etymological information provided in the Polish Academy of Sciences Great Dictionary of Polish (Pol. Wielki słownik języka polskiego PAN, WSJP PAN). The dictionary and the rules of producing the entries are briefly presented. These rules influence the way of working on etymology within ...

  7. Polish Qualitative Sociology. Insight into the future of postdisciplinary research

    OpenAIRE

    Konecki, Krzysztof

    2014-01-01

    The paper desctibes the definitions of following concepts: multidisiplinarity, interdisciplinarity, transdysciplinarity, postdisciplinarity. MOreover it discuss the meanings of a concept of discipline. It describes the place of the Polish qualitative sociology in the context of postdisciplinary research. The main question of paper is: Does the POlish Qualitative Sociology has entered the postdisciplinary phase of research? DGS, UL Krzysztof Konecki

  8. Effects of surface polishing and annealing on the optical conductivity of intermetallic compounds

    International Nuclear Information System (INIS)

    Rhee, Joo Yull

    1999-01-01

    The optical conductivity spectra of several intermetallic compounds were measured by spectroscopic ellipsometry. Three spectra were measured for each compound; just after the sample was mechanically polished, at high temperature, and after the sample was annealed at 110 .deg. C for at least one day and cooled to room temperature. An equiatomic FeTi alloy showed the typical effects of annealing after mechanical polishing of surface. The spectrum after annealing had a larger magnitude and sharper structures than the spectrum before annealing. We also observed shifts of peaks in the spectrum. A relatively low-temperature annealing gave rise to unexpectedly substantial effects, and the effects were explained by recrystallization and/or a disorder → order transition of the surface of the sample which was damaged and, hence, became highly disordered by mechanical polishing. Similar effects were also observed when the sample temperature was lowered. The observed changes upon annealing could partly be explained by presumption that the recrystallization would be realized in such a way that the average atomic spacing would be reduced

  9. Note on the polishing of small spheres of ferrimagnetic materials

    Energy Technology Data Exchange (ETDEWEB)

    Grunberg, J. G.; Antier, G. [Centre d' etudes nucleaires de Grenoble - C.E.N.G. (France); Seiden, P. E. [Institut Fourier, Universite de Grenoble (France)

    1961-07-01

    This note describes a simple and rapid method that we have used for obtaining a high degree of polish on spheres of ferrimagnetic materials. A high surface polish is of particular importance if one desires to perform ferrimagnetic resonance experiments on very narrow linewidth materials such as Yttrium Iron Garnet. It is not possible to obtain the very narrow linewidths without polishing the sample with a very fine abrasive such as 'Linde A'. Although the methods presently used for the fine polishing of ferrite spheres give satisfactory results, the method described here is of particular interest because of its simplicity and speed. For example with the air-jet tumbling technique it can take as long as three days of polishing to obtain an acceptable surface while our method will give the same results in one to two hours. (author)

  10. Microstructures and mechanical properties of Cu/Ti{sub 3}SiC{sub 2}/C/MWCNTs composites prepared by vacuum hot-pressing sintering

    Energy Technology Data Exchange (ETDEWEB)

    Xiaosong, Jiang, E-mail: xsjiang@yeah.net [School of Materials Science and Engineering, Southwest Jiaotong University, Chengdu, Sichuan 610031 (China); Liu, Wanxia; Li, Jingrui [School of Materials Science and Engineering, Southwest Jiaotong University, Chengdu, Sichuan 610031 (China); Shao, Zhenyi [Department of Mechanical Engineering, Chengdu Technological University, Chengdu, Sichuan 610031 (China); Zhu, Degui [School of Materials Science and Engineering, Southwest Jiaotong University, Chengdu, Sichuan 610031 (China)

    2015-01-05

    Highlights: • Cu/Ti{sub 3}SiC{sub 2}/C/MWCNTs composites were prepared using vacuum hot-pressing sintering. • Dispersions of MWCNTs were prepared using 10 μg/ml gallic acid aqueous solution. • MWCNTs content has no effect on generation of TiC and Cu{sub 9}Si to effect matrix’s performance. - Abstract: Cu/Ti{sub 3}SiC{sub 2}/C/MWCNTs composites were prepared by vacuum hot-pressing sintering. Microstructures and mechanical properties of Cu/Ti{sub 3}SiC{sub 2}/C/MWCNTs composites with different multi-walled carbon nanotubes contents have been systematically investigated. The microstructures of the composites were examined by optical microscopy, X-ray diffraction, back scattered electron imaging, scanning electron microscope and energy dispersive spectrometer. The mechanical properties were determined from Brinell hardness and tensile tests. The results demonstrated that there was an optimum value of MWCNTs content which has an impact on microstructures and mechanical properties of Cu/Ti{sub 3}SiC{sub 2}/C/MWCNTs composites. Based on MWCNTs content on properties and microstructure of Cu/Ti{sub 3}SiC{sub 2}/C/MWCNTs composites, effects of MWCNTs on improvement of the composites and strengthening mechanism have been analyzed.

  11. Chemical polishing of partially oxidized T-111 alloy

    International Nuclear Information System (INIS)

    Teaney, P.E.

    1974-01-01

    The specimens were pressure-mounted in Bakelite and ground through 600 grit on silicon carbide papers. The specimens were rough-polished on a vibratory polisher for 4 to 6 h, using a water slurry of one micron alumina on Texmet, followed by 0.3-μ alumina on Texmet overnight. Final polishing was accomplished by continuous swabbing with a chemical polish. A chemical polish consisting of ten parts lactic acid, four parts nitric acid, and four parts hydrofluoric acid worked well for the T-111 parent material specimens; however, in the partially oxidized specimens, considerable pitting and staining occurred in the oxygen-affected zone and in the transition zone between the oxygen-affected zone and the parent material. A chemical polish was developed for the partially oxidized specimens by adjusting the ratio of the acids to ten parts lactic acid, two parts nitric acid, and two parts hydrofluoric acid. This slowed the chemical attack on the oxygen-affected zone considerably and, with continuous swabbing, the pitting and stain could be avoided. The specimens were rinsed and checked occasionally on the metallograph to determine when the proper polish had been obtained. Some specimens required intermittent polishing times up to 1 / 2 hour. No relationship could be established between the oxygen content of the specimen and the time required for chemical polishing in the partially oxidized specimens. However, the microstructure of the transition zone was the most difficult to obtain, and specimens with uniform reaction zones across the width of the specimen polished quicker than those with the transition zone

  12. THE SOCIALIST YOUTH UNION (1957–1976 – POLISH COUNTERPART OF KOMSOMOL

    Directory of Open Access Journals (Sweden)

    Joanna Sadowska

    2016-10-01

    Full Text Available The political system of the Polish People’s Republic was modelled on the Soviet one. Polish youth organizations had the ambitions of being counterparts of Komsomol: they adopted similar work methods and tried to play a similar role in the country. The obvious differences resulted from the specificity of each country and the differences in the societies. The most deeply rooted in the memory of Poles is the Socialist Youth Union, which, being the most stable, existed for almost 20 years with nearly 1.3 million members in the early 1970s. The Union was closely connected with the Polish United Workers’ Party and it had to accomplish two main kinds of political task: to select and prepare future members of the Party, both ordinary and those in the managerial positions, and to educate the whole young generation. The Party indeed treated the organization as its agency, an office dealing with the affairs of youths. However, non-political activity of the Union (culture, entertainment, tourism, etc. was much more effective and evaluated more positively. Actually, there was much more falsehood in the Union: many members were almost completely passive and the work was often only simulated.

  13. Antigenic typing Polish isolates of canine parvovirus

    Energy Technology Data Exchange (ETDEWEB)

    Mizak, B. [National Veterinary Research Institute, Pulawy (Poland); Plucienniczak, A. [Polish Academy ofd Sciences. Microbiology and Virology Center, Lodz (Poland)

    1995-12-31

    Polish strains of canine parvovirus isolated between 1982 and 1993 were examined to determine the extent to which the virus has evolved antigenically and genetically over eleven years. Two CPV isolates obtained in Warsaw in 1982 and Pulawy in 1993, were examined using monoclonal antibody typing, restriction analysis and sequencing VP-2 protein gene. Five other isolates from Warsaw and Pulawy were tested with the panel of monoclonal antibodies specific to CPV-2, CPV-2a and common for canine parvovirus, feline panleukopenia virus and milk enteritis virus. Results of the studies demonstrated that all isolates tested represented CPV-2a antigenic type. Rapid antigenic strain replacement recorded by Parrish and Senda in the U.S.A and Japan was not confirmed in Poland. (author). 30 refs, 2 tabs.

  14. Food patterns of Polish older people

    DEFF Research Database (Denmark)

    Wadolowska, L.; Danowska-Oziewicz, M.; Niedzwiedzka, E.

    2006-01-01

    Food patterns of Polish older people were separated and described. The research included 422 people aged 65+ years, living in 5 geographical locations. Participants of the study were selected in quota sampling. Criteria for recruitment included sex, age (65-^74 or 75+ years) and family status...... (living alone or living with other people). Respondents were asked questions about consumption of 55 food products. The factor analysis allowed for separating 21 food patterns. They included from 1 to 3 groups of products, intake of which was mutually dependant. Big number of separated food patterns...... and small number of products fonning joint food patterns speak in advocacy of relatively small reciprocal relationship between different food items consumed by the seniors in Poland....

  15. Antigenic typing Polish isolates of canine parvovirus

    International Nuclear Information System (INIS)

    Mizak, B.; Plucienniczak, A.

    1995-01-01

    Polish strains of canine parvovirus isolated between 1982 and 1993 were examined to determine the extent to which the virus has evolved antigenically and genetically over eleven years. Two CPV isolates obtained in Warsaw in 1982 and Pulawy in 1993, were examined using monoclonal antibody typing, restriction analysis and sequencing VP-2 protein gene. Five other isolates from Warsaw and Pulawy were tested with the panel of monoclonal antibodies specific to CPV-2, CPV-2a and common for canine parvovirus, feline panleukopenia virus and milk enteritis virus. Results of the studies demonstrated that all isolates tested represented CPV-2a antigenic type. Rapid antigenic strain replacement recorded by Parrish and Senda in the U.S.A and Japan was not confirmed in Poland. (author). 30 refs, 2 tabs

  16. Structure and mechanical properties of Al-Si-Fe alloys prepared by short-term mechanical alloying and Spark Plasma Sintering

    Czech Academy of Sciences Publication Activity Database

    Průša, J.; Vojtěch, D.; Bláhová, M.; Michalcová, A.; Kubatík, Tomáš František; Čížek, J.

    2015-01-01

    Roč. 75, June (2015), s. 65-75 ISSN 0261-3069 Institutional support: RVO:61389021 Keywords : Aluminium alloy s * Mechanical Properties * Microstructure * Mechanical alloy ing * Spark-Plasma Sintering Subject RIV: JG - Metallurgy Impact factor: 3.997, year: 2015 http://www.sciencedirect.com/science/article/pii/S0261306915000990#

  17. The effects of crosslinkers on physical, mechanical, and cytotoxic properties of gelatin sponge prepared via in-situ gas foaming method as a tissue engineering scaffold

    Energy Technology Data Exchange (ETDEWEB)

    Poursamar, S. Ali [Institute for Creative Leather Technologies, Park Campus, The University of Northampton, Boughton Green Road, Northampton NN2 7AL (United Kingdom); Lehner, Alexander N. [Centre for Physical Activity and Chronic Disease and the Aging Research Centre, Institute for Health and Wellbeing, School of Health, Park Campus, The University of Northampton, Boughton Green Road, Northampton NN2 7AL (United Kingdom); Azami, Mahmoud; Ebrahimi-Barough, Somayeh [Department of Tissue Engineering, School of Advanced Technologies in Medicine, Tehran University of Medical Sciences, Tehran (Iran, Islamic Republic of); Samadikuchaksaraei, Ali [Cellular and Molecular Research Centre, Iran University of Medical Sciences, Tehran (Iran, Islamic Republic of); Department of Tissue Engineering & Regenerative Medicine, Faculty of Advanced Technologies in Medicine, Iran University of Medical Sciences, Tehran (Iran, Islamic Republic of); Department of Medical Biotechnology, Faculty of Applied Medicine, Iran University of Medical Sciences, Tehran (Iran, Islamic Republic of); Antunes, A.P.M., E-mail: Paula.Antunes@northampton.ac.uk [Institute for Creative Leather Technologies, Park Campus, The University of Northampton, Boughton Green Road, Northampton NN2 7AL (United Kingdom)

    2016-06-01

    In this study porous gelatin scaffolds were prepared using in-situ gas foaming, and four crosslinking agents were used to determine a biocompatible and effective crosslinker that is suitable for such a method. Crosslinkers used in this study included: hexamethylene diisocyanate (HMDI), poly(ethylene glycol) diglycidyl ether (epoxy), glutaraldehyde (GTA), and genipin. The prepared porous structures were analyzed using Fourier Transform Infrared Spectroscopy (FT-IR), thermal and mechanical analysis as well as water absorption analysis. The microstructures of the prepared samples were analyzed using Scanning Electron Microscopy (SEM). The effects of the crosslinking agents were studied on the cytotoxicity of the porous structure indirectly using MTT analysis. The affinity of L929 mouse fibroblast cells for attachment on the scaffold surfaces was investigated by direct cell seeding and DAPI-staining technique. It was shown that while all of the studied crosslinking agents were capable of stabilizing prepared gelatin scaffolds, there are noticeable differences among physical and mechanical properties of samples based on the crosslinker type. Epoxy-crosslinked scaffolds showed a higher capacity for water absorption and more uniform microstructures than the rest of crosslinked samples, whereas genipin and GTA-crosslinked scaffolds demonstrated higher mechanical strength. Cytotoxicity analysis showed the superior biocompatibility of the naturally occurring genipin in comparison with other synthetic crosslinking agents, in particular relative to GTA-crosslinked samples. - Highlights: • In-situ gas foaming application in the production of sponge-like gelatin structures • The crosslinkers molecular length impacts on the physical and mechanical properties of the structure. • The effect of crosslinkers on the biocompatibility of gelatin scaffolds.

  18. The effects of crosslinkers on physical, mechanical, and cytotoxic properties of gelatin sponge prepared via in-situ gas foaming method as a tissue engineering scaffold

    International Nuclear Information System (INIS)

    Poursamar, S. Ali; Lehner, Alexander N.; Azami, Mahmoud; Ebrahimi-Barough, Somayeh; Samadikuchaksaraei, Ali; Antunes, A.P.M.

    2016-01-01

    In this study porous gelatin scaffolds were prepared using in-situ gas foaming, and four crosslinking agents were used to determine a biocompatible and effective crosslinker that is suitable for such a method. Crosslinkers used in this study included: hexamethylene diisocyanate (HMDI), poly(ethylene glycol) diglycidyl ether (epoxy), glutaraldehyde (GTA), and genipin. The prepared porous structures were analyzed using Fourier Transform Infrared Spectroscopy (FT-IR), thermal and mechanical analysis as well as water absorption analysis. The microstructures of the prepared samples were analyzed using Scanning Electron Microscopy (SEM). The effects of the crosslinking agents were studied on the cytotoxicity of the porous structure indirectly using MTT analysis. The affinity of L929 mouse fibroblast cells for attachment on the scaffold surfaces was investigated by direct cell seeding and DAPI-staining technique. It was shown that while all of the studied crosslinking agents were capable of stabilizing prepared gelatin scaffolds, there are noticeable differences among physical and mechanical properties of samples based on the crosslinker type. Epoxy-crosslinked scaffolds showed a higher capacity for water absorption and more uniform microstructures than the rest of crosslinked samples, whereas genipin and GTA-crosslinked scaffolds demonstrated higher mechanical strength. Cytotoxicity analysis showed the superior biocompatibility of the naturally occurring genipin in comparison with other synthetic crosslinking agents, in particular relative to GTA-crosslinked samples. - Highlights: • In-situ gas foaming application in the production of sponge-like gelatin structures • The crosslinkers molecular length impacts on the physical and mechanical properties of the structure. • The effect of crosslinkers on the biocompatibility of gelatin scaffolds

  19. Popularity of marijuana among Polish students

    Directory of Open Access Journals (Sweden)

    Michał Pająk

    2017-09-01

    Full Text Available Introduction and the aim: Marijuana is the most commonly used drug in the world (excluding alcohol and tobacco. According to the literature about 16% of Poles at the age of 16 to 64 years old, at least once have used cannabis. The aim of study was to estimate the popularity of marijuana among students of Polish universities. We also asked questions about respondents’ attitude towards marijuana and opinions about its validation. Material and methods: The study was conducted in 2017 on 132 individuals – 60 men and 72 women. The results were analyzed in STATISTICA 10 at p<0.05. Results:Out of interviewees, 63.6% of them, at least once in their lives, have used marijuana. This is a percentage of up to four times greater than that one given in the literature for the general population. Even 80% of men and 50% of women have tried marijuana at least once in their lives. Students of Catholic University of Lublin reach for marijuana significantly more often than students of Medical University of Lublin. The majority of respondents (53% treats marijuana as a "soft" drug, though up 67.4% believe that it has the addictive potential. More than a half of respondents (56.8% stands for liberalization of rules relevant to marijuana in Poland. Vast majority (70% of respondents believes that marijuana is easily available in Poland. Conclusions: Marijuana is a drug popular among students. The criminalization of drug use in Poland is not effective for the prevention of its use, the majority of respondents believes that marijuana is easily available in Poland. Considering the negative health and social consequences of the current state, it is worth wondering about making changes in the education system and Polish drug law.

  20. Droughts in historical times in Polish territory

    Science.gov (United States)

    Limanowka, Danuta; Cebulak, Elzbieta; Pyrc, Robert; Doktor, Radoslaw

    2015-04-01

    Climate change is one of the key environmental, social and economical issues, and it is also followed by political consequences. Impact of climate conditions on countries' economy is increasingly recognized, and a lot of attention is given, both in the global scale and by the individual national governments. In years 2008-2010, at the Poland -Institute of Meteorology and Water Management-National Research Institute was realized the KLIMAT Project on Impact of climate change on environment, economy and society (changes, effects and methods of reducing them, conclusions for science, engineering practice and economic planning) No. POIG01-03-01-14-011/08. The project was financed by the European Union and Polish state budget in frame of Innovative Economy Operational Programme. A very wide range of research was carried out in the different thematic areas. One of them was "Natural disasters and internal safety of the country (civil and economical)." The problem of drought in Poland was developed in terms of meteorology and hydrology. "Proxy" Data Descriptions very often inform about dry years and seasons, hot periods without precipitation. Analysis of historical material allowed to extract the years that have experienced prolonged periods of high temperatures and rainfall shortages. Weather phenomenon defined as drought belongs to extreme events. This information was very helpful in the process of indexing and thus to restore the course and intensity of climatic elements in the past. The analysis covered the period from year 1000 to modern times. Due to the limited information from the period of 1000-1500 the authors focused primarily on the period from 1500 to 2010. Analysis of the collected material has allowed the development of a highly precise temporal structure of the possible occurrence of dry periods to Polish territory.

  1. Surface texture of resin-modified glass ionomer cements: effects of finishing/polishing systems.

    Science.gov (United States)

    Yap, Adrian U J; Tan, W S; Yeo, J C; Yap, W Y; Ong, S B

    2002-01-01

    This study investigated the surface texture of two resin-modified glass ionomer cements (RMGICs) in the vertical and horizontal axis after treatment with different finishing/polishing systems. Class V preparations were made on the buccal and lingual/palatal surfaces of freshly extracted teeth. The cavities on each tooth were restored with Fuji II LC (GC) and Photac-Fil Quick (ESPE) according to manufacturers' instructions. Immediately after light-polymerization, gross finishing was done with 8-flute tungsten carbide burs. The teeth were then randomly divided into four groups and finished/polished with (a) Robot Carbides (RC); (b) Super-Snap system (SS); (c) OneGloss (OG) and (d) CompoSite Points (CS). The sample size for each material-finishing/polishing system combination was eight. The mean surface roughness (microm) in vertical (RaV) and horizontal (RaH) axis was measured using a profilometer. Data was subjected to ANOVA/Scheffe's tests and Independent Samples t-test at significance level 0.05. Mean RaV ranged from 0.59-1.31 and 0.83-1.52, while mean RaH ranged from 0.80-1.43 and 0.85-1.58 for Fuji II LC and Photac-Fil, respectively. Results of statistical analysis were as follows: Fuji II LC: RaV-RC, SSpolishing of RMGICs is not recommended. Graded abrasive disk (SS) or two-step rubber abrasive (CS) systems should be used instead.

  2. Evaluation and analysis of polished fused silica subsurface quality by the nanoindenter technique

    International Nuclear Information System (INIS)

    Ma Bin; Shen Zhengxiang; He Pengfei; Sha Fei; Wang Chunliang; Wang Bin; Ji Yiqin; Liu Huasong; Li Weihao; Wang Zhanshan

    2011-01-01

    We evaluate the subsurface quality of polished fused silica samples using the nanoindenter technique. Two kinds of samples, consisting of hundreds of nanometers and micrometers of subsurface damage layers, are fabricated by controlling the grinding and polishing processes, and the subsurface quality has been verified by the chemical etching method. Then several nanoindentation experiments are performed using the Berkovich tip to investigate the subsurface quality. Some differences are found by relative measurements in terms of the relationship between the total penetration and the peak load on the surfaces, the modulus calculated over the defined depths and from unload, and the indented morphology at a constant load near the surface collapse threshold. Finally, the capabilities of such a mechanical method for detecting subsurface flaws are discussed and analyzed.

  3. Effects of sintering temperature on the mechanical properties of sintered NdFeB permanent magnets prepared by spark plasma sintering

    International Nuclear Information System (INIS)

    Wang, G.P.; Liu, W.Q.; Huang, Y.L.; Ma, S.C.; Zhong, Z.C.

    2014-01-01

    Sintered NdFeB-based permanent magnets were fabricated by spark plasma sintering (SPS) and a conventional method to investigate the mechanical and magnetic properties. The experimental results showed that sintered NdFeB magnet prepared by the spark plasma sintering (SPS NdFeB) possesses a better mechanical properties compared to the conventionally sintered one, of which the maximum value of bending strength and Vickers hardness was 402.3 MPa and 778.1 MPa, respectively. The effects of sintering temperature on bending strength and Vickers hardness were investigated. It was shown that the bending strength firstly increases to the maximum value and then decreases with the increase of sintering temperature in a certain range. The investigations of microstructures and mechanical properties indicated that the unique sintering mechanism in the SPS process is responsible for the improvement of mechanical properties of SPS NdFeB. Furthermore, the relations between the mechanical properties and relevant microstructure have been analyzed based on the experimental fact. - Highlights: • Studied the sintering temperature effect on strengthening mechanism of NdFeB magnet firstly. • It showed that sintering temperature may effectively affect the mechanical properties. • The maximum bending strength and Vickers hardness was 402.3 MPa and 778.1 MPa, respectively

  4. Effects of sintering temperature on the mechanical properties of sintered NdFeB permanent magnets prepared by spark plasma sintering

    Energy Technology Data Exchange (ETDEWEB)

    Wang, G.P., E-mail: wgp@jxnu.edu.cn [College of Physics and Communication Electronics, Jiangxi Normal University, Nanchang 330022 (China); Liu, W.Q. [Key Laboratory of Advanced Functional Materials Science and Engineering, Ministry of Education, Beijing University of Technology, Beijing 100022 (China); Huang, Y.L.; Ma, S.C.; Zhong, Z.C. [School of Materials Science and Engineering, Nanchang Hangkong University, Nanchang 330063 (China)

    2014-01-15

    Sintered NdFeB-based permanent magnets were fabricated by spark plasma sintering (SPS) and a conventional method to investigate the mechanical and magnetic properties. The experimental results showed that sintered NdFeB magnet prepared by the spark plasma sintering (SPS NdFeB) possesses a better mechanical properties compared to the conventionally sintered one, of which the maximum value of bending strength and Vickers hardness was 402.3 MPa and 778.1 MPa, respectively. The effects of sintering temperature on bending strength and Vickers hardness were investigated. It was shown that the bending strength firstly increases to the maximum value and then decreases with the increase of sintering temperature in a certain range. The investigations of microstructures and mechanical properties indicated that the unique sintering mechanism in the SPS process is responsible for the improvement of mechanical properties of SPS NdFeB. Furthermore, the relations between the mechanical properties and relevant microstructure have been analyzed based on the experimental fact. - Highlights: • Studied the sintering temperature effect on strengthening mechanism of NdFeB magnet firstly. • It showed that sintering temperature may effectively affect the mechanical properties. • The maximum bending strength and Vickers hardness was 402.3 MPa and 778.1 MPa, respectively.

  5. A novel inorganic precipitation-peptization method for VO2 sol and VO2 nanoparticles preparation: Synthesis, characterization and mechanism.

    Science.gov (United States)

    Li, Yao; Jiang, Peng; Xiang, Wei; Ran, Fanyong; Cao, Wenbin

    2016-01-15

    In this paper, a simple, safe and cost-saving precipitation-peptization method was proposed to prepare VO2 sol by using inorganic VOSO4-NH3⋅H2O-H2O2 reactants system in air under room temperature. In this process, VOSO4 was firstly precipitated to form VO(OH)2, then monometallic species of VO(O2)(OH)(-) were formed through the coordination between VO(OH)2 and H2O2. The rearrangement of VO(O2)(OH)(-) in a nonplanar pattern and intermolecular condensation reactions result in multinuclear species. Finally, VO2 sol is prepared through the condensation reactions between the multinuclear species. After drying the obtained sol at 40°C, VO2 xerogel exhibiting monoclinic crystal structure with the space group of C2/m was prepared. The crystal structure of VO2 nanoparticles was transferred to monoclinic crystal structure with the space group of P21/c (VO2(M)) by annealing the xerogel at 550°C. Both XRD and TEM analysis indicated that the nanoparticles possess good crystallinity with crystallite size of 34.5nm as estimated by Scherrer's method. These results suggest that the VO2 sol has been prepared successfully through the proposed simple method. Copyright © 2015 Elsevier Inc. All rights reserved.

  6. New perspectives in hydrodynamic radial polishing techniques for optical surfaces

    Science.gov (United States)

    Ruiz, Elfego; Sohn, Erika; Luna, Esteban; Salas, Luis; Cordero, Alberto; González, Jorge; Núñez, Manuel; Salinas, Javier; Cruz-González, Irene; Valdés, Jorge; Cabrera, Victor; Martínez, Benjamín

    2004-09-01

    In order to overcome classic polishing techniques, a novel hydrodynamic radial polishing tool (HyDRa) is presented; it is useful for the corrective lapping and fine polishing of diverse materials by means of a low-cost abrasive flux and a hydrostatic suspension system that avoids contact of the tool with the working surface. This tool enables the work on flat or curved surfaces of currently up to two and a half meters in diameter. It has the advantage of avoiding fallen edges during the polishing process as well as reducing tool wear out and deformation. The functioning principle is based on the generation of a high-velocity, high-pressure, abrasive emulsion flux with radial geometry. The polishing process is repeatable by means of the control of the tool operational parameters, achieving high degrees of precision and accuracy on optical and semiconductor surfaces, with removal rates of up to 9 mm3/hour and promising excellent surface polishing qualities. An additional advantage of this new tool is the possibility to perform interferometric measurements during the polishing process without the need of dismounting the working surface. A series of advantages of this method, numerical simulations and experimental results are described.

  7. Opinions of Polish occupational medicine physicians on workplace health promotion.

    Science.gov (United States)

    Puchalski, Krzysztof; Korzeniowska, Elzbieta; Pyzalski, Jacek; Wojtaszczyk, Patrycja

    2005-01-01

    According to the current Polish legislation on occupational health services, occupational medicine physicians should perform workplace health promotion (WHP) activities as a part of their professional work. The concept of workplace health promotion or health promotion programs, however, has not been defined in this legislation in any way. Therefore, two essential questions arise. First, what is the physicians' attitude towards workplace health issues and second, what is actually carried out under the label of health promotion? The main objective of the research described in this paper was to answer these questions. The survey was carried out by the National Center for Workplace Health Promotion in 2002. A questionnaire prepared by the Center for the purpose of this survey was sent to a random sample of occupational medicine physicians. The results of the survey showed that 53% of occupational medicine physicians consider WHP just as a new name for prophylactics. On the other hand almost all of the respondents (94%) agree that occupational medicine physicians should perform WHP activities and find them useful in improving patients' health (78%). The main obstacle for the development of this activity in the perception of physicians is the lack of interest in workplace health promotion among employers (86%). In the modern understanding of workplace health promotion concept this type of intervention includes not only safety measures and health education, but also a profound organizational change that allows employers, employees and social partners to improve wellbeing of people at work. Each of such projects should facilitate changes necessary to create a health promoting workplace. It also needs a skilled leader--well trained and aware of a multidisciplinary dimension of WHP interventions. Occupational medicine specialists should become natural partners of employers and employees. The majority of the occupational medicine physicians, however, are not sufficiently

  8. 8. All Polish Conference on Analytical Chemistry: Analytical Chemistry for the Community of the 21. Century

    International Nuclear Information System (INIS)

    Koscielniak, P.; Wieczorek, M.; Kozak, J.

    2010-01-01

    Book of Abstracts contains short descriptions of lectures, communications and posters presented during 8 th All Polish Conference on Analytical Chemistry (Cracow, 4-9.07.2010). Scientific programme consisted of: basic analytical problems, preparation of the samples, chemometry and metrology, miniaturization of the analytical procedures, environmental analysis, medicinal analyses, industrial analyses, food analyses, biochemical analyses, analysis of relicts of the past. Several posters were devoted to the radiochemical separations, radiochemical analysis, environmental behaviour of the elements important for the nuclear science and the professional tests.

  9. A preliminary study in zero anaphora coreference resolution for Polish

    Directory of Open Access Journals (Sweden)

    Adam Jan Kaczmarek

    2017-12-01

    Full Text Available A preliminary study in zero anaphora coreference resolution for Polish Zero anaphora is an element of the coreference resolution task that has not yet been directly addressed in Polish and, in most studies, it has been left as the most challenging aspect for further investigation. This article presents an initial study of this problem. The preparation of a machine learning approach, alongside engineering features based on linguistic study of the KPWr corpus, is discussed. This study utilizes existing tools for Polish coreference resolution as sources of partial coreferential clusters containing pronoun, noun and named entity mentions. They are also used as baseline zero coreference resolution systems for comparison with our system. The evaluation process is focused not only on clustering correctness, without taking into account types of mentions, using standard CoNLL-2012 measures, but also on the informativeness of the resulting relations. According to the annotation approach used for coreference to the KPWr corpus, only named entities are treated as mentions that are informative enough to constitute a link to real world objects. Consequently, we provide an evaluation of informativeness based on found links between zero anaphoras and named entities. For the same reason, we restrict coreference resolution in this study to mention clusters built around named entities.   Wstępne studium rozwiązywania problemu koreferencji anafory zerowej w języku polskim Koreferencja zerowa, w języku polskim, jest jednym z zagadnień rozpoznawania koreferencji. Dotychczas nie była ona bezpośrednim przedmiotem badań, gdyż ze względu na jej złożoność była pomijana i odsuwana na dalsze etapy badań. Artykuł prezentuje wstępne studium problemu, jakim jest rozpoznawanie koreferencji zerowej. Przedstawiamy podejście wykorzystujące techniki uczenia maszynowego oraz proces tworzenia cech w oparciu o analizę lingwistyczną korpusu KPWr. W przedstawionej

  10. Polishing Sapphire Substrates by 355 nm Ultraviolet Laser

    Directory of Open Access Journals (Sweden)

    X. Wei

    2012-01-01

    Full Text Available This paper tries to investigate a novel polishing technology with high efficiency and nice surface quality for sapphire crystal that has high hardness, wear resistance, and chemical stability. A Q-switched 355 nm ultraviolet laser with nanosecond pulses was set up and used to polish sapphire substrate in different conditions in this paper. Surface roughness Ra of polished sapphire was measured with surface profiler, and the surface topography was observed with scanning electronic microscope. The effects of processing parameters as laser energy, pulse repetition rate, scanning speed, incident angle, scanning patterns, and initial surface conditions on surface roughness were analyzed.

  11. Presentation of the verbs in Bulgarian-Polish electronic dictionary

    Directory of Open Access Journals (Sweden)

    Ludmila Dimitrova

    2014-09-01

    Full Text Available Presentation of the verbs in Bulgarian-Polish electronic dictionary This paper briefly discusses the presentation of the verbs in the first electronic Bulgarian-Polish dictionary that is currently being developed under a bilateral collaboration between IMI-BAS and ISS-PAS. Special attention is given to the digital entry classifiers that describe Bulgarian and Polish verbs. Problems related to the correspondence between natural language phenomena and their presentations are discussed. Some examples illustrate the different types of dictionary entries for verbs.

  12. "Agricultural budget" and the competitiveness of the Polish agriculture

    OpenAIRE

    Lenkiewicz, Stanisław; Rokicki, Bartłomiej

    2014-01-01

    The aim of the publication is to assess the impact of public support on the functioning of the Polish agriculture. In order to achieve this aim the publication includes an analysis of the system of direct payments and rural development policy instruments planned to be implemented in Poland within the CAP 2014-2020. The study also presents an analysis of regional diversity of the Polish agriculture and an assessment of the scale of agricultural investment made in recent years in all the Polish...

  13. Surface polishing of niobium for superconducting radio frequency (SRF) cavity applications

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Liang [College of William and Mary, Williamsburg, VA (United States)

    2014-08-01

    Niobium cavities are important components in modern particle accelerators based on superconducting radio frequency (SRF) technology. The interior of SRF cavities are cleaned and polished in order to produce high accelerating field and low power dissipation on the cavity wall. Current polishing methods, buffered chemical polishing (BCP) and electro-polishing (EP), have their advantages and limitations. We seek to improve current methods and explore laser polishing (LP) as a greener alternative of chemical methods. The topography and removal rate of BCP at different conditions (duration, temperature, sample orientation, flow rate) was studied with optical microscopy, scanning electron microscopy (SEM), and electron backscatter diffraction (EBSD). Differential etching on different crystal orientations is the main contributor to fine grain niobium BCP topography, with gas evolution playing a secondary role. The surface of single crystal and bi-crystal niobium is smooth even after heavy BCP. The topography of fine grain niobium depends on total removal. The removal rate increases with temperature and surface acid flow rate within the rage of 0~20 °C, with chemical reaction being the possible dominate rate control mechanism. Surface flow helps to regulate temperature and avoid gas accumulation on the surface. The effect of surface flow rate on niobium EP was studied with optical microscopy, atomic force microscopy (AFM), and power spectral density (PSD) analysis. Within the range of 0~3.7 cm/s, no significant difference was found on the removal rate and the macro roughness. Possible improvement on the micro roughness with increased surface flow rate was observed. The effect of fluence and pulse accumulation on niobium topography during LP was studied with optical microscopy, SEM, AFM, and PSD analysis. Polishing on micro scale was achieved within fluence range of 0.57~0.90 J/cm2, with pulse accumulation adjusted accordingly. Larger area treatment was proved possible by

  14. Cone-beam computed tomography analysis of curved root canals after mechanical preparation with three nickel-titanium rotary instruments

    Science.gov (United States)

    Elsherief, Samia M.; Zayet, Mohamed K.; Hamouda, Ibrahim M.

    2013-01-01

    Cone beam computed tomography is a 3-dimensional high resolution imaging method. The purpose of this study was to compare the effects of 3 different NiTi rotary instruments used to prepare curved root canals on the final shape of the curved canals and total amount of root canal transportation by using cone-beam computed tomography. A total of 81 mesial root canals from 42 extracted human mandibular molars, with a curvature ranging from 15 to 45 degrees, were selected. Canals were randomly divided into 3 groups of 27 each. After preparation with Protaper, Revo-S and Hero Shaper, the amount of transportation and centering ability that occurred were assessed by using cone beam computed tomography. Utilizing pre- and post-instrumentation radiographs, straightening of the canal curvatures was determined with a computer image analysis program. Canals were metrically assessed for changes (surface area, changes in curvature and transportation) during canal preparation by using software SimPlant; instrument failures were also recorded. Mean total widths and outer and inner width measurements were determined on each central canal path and differences were statistically analyzed. The results showed that all instruments maintained the original canal curvature well with no significant differences between the different files (P = 0.226). During preparation there was failure of only one file (the protaper group). In conclusion, under the conditions of this study, all instruments maintained the original canal curvature well and were safe to use. Areas of uninstrumented root canal wall were left in all regions using the various systems. PMID:23885273

  15. Characterization and mechanical investigation of Ti–O2−x film prepared by plasma immersion ion implantation and deposition for cardiovascular stents surface modification

    International Nuclear Information System (INIS)

    Xie Dong; Wan Guojiang; Maitz, Manfred F.; Lei Yifeng; Huang Nan; Sun Hong

    2012-01-01

    Highlights: ► We prepared Ti–O 2−x films of good quality by PIII and D successfully on stents product. ► The Ti–O 2−x film shows good homogeneity and intergradient film/substrate interface. ► The Ti–O 2−x films on stent sustain clinically-required expansion without failure. ► The films show good mechanical durability for cardiovascular stents application. - Abstract: Up to date, materials for cardiovascular stents are still far from satisfactory because of high risk of biomaterials-associated restenosis and thrombosis. Extensive efforts have been made to improve the biocompatibility of the materials by various surface modification techniques. Ti–O 2−x films prepared by plasma immersion ion implantation and deposition (PIII and D) have shown good blood compatibility. For clinical application, surface quality and mechanical durability of the Ti–O 2−x film on stents are also of critical importance for the long-term serving. In this paper we present our research results on surface quality, mechanical investigation and characterization of Ti–O 2−x films prepared using PIII and D on stent products provided by Boston Scientific SCIMED. Ti–O 2−x films with mostly Rutile and little non-stoichiometric phases were obtained with smoothness of 2−x films on stents products were sustained balloon-expansion of clinically-required extent without mechanical failure, showing highly potential feasibility for cardiovascular stents application.

  16. Properties and toughening mechanisms of PVA/PAM double-network hydrogels prepared by freeze-thawing and anneal-swelling.

    Science.gov (United States)

    Ou, Kangkang; Dong, Xia; Qin, Chengling; Ji, Xinan; He, Jinxin

    2017-08-01

    It is well known that preparation method of hydrogels has a significant effect on their properties. In this paper, freeze-thawing and anneal-swelling were applied to prepare poly(vinyl alcohol)/polyacrylamide (PVA/PAM) double-network hydrogels with covalently and physically cross-linked networks. The properties of these hydrogels were investigated and compared to control hydrogels. Results indicated that hydrogels fabricated by freeze-thawing show larger pores size and higher swelling capacity than those made by anneal-swelling and c