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Sample records for chemical mechanical polishing

  1. Tribology analysis of chemical-mechanical polishing

    Energy Technology Data Exchange (ETDEWEB)

    Runnels, S.R.; Eyman, L.M. (Sematech, Austin, TX (United States))

    1994-06-01

    To better understand the variation of material removal rate on a wafer during chemical-mechanical polishing (CMP), knowledge of the stress distribution on the wafer surface is required. The difference in wafer-surface stress distributions could be considerable depending on whether or not the wafer hydroplanes during polishing. This study analyzes the fluid film between the wafer and pad and demonstrates that hydroplaning is possible for standard CMP processes. The importance of wafer curvature, slurry viscosity, and rotation speed on the thickness of the fluid film is also demonstrated.

  2. Chemical Mechanical Polishing of Silicon Carbide

    Science.gov (United States)

    Powell, J. Anthony; Pirouz

    1999-01-01

    The High Temperature Integrated Electronics and Sensors (HTIES) team at the NASA Lewis Research Center is developing silicon carbide (SiC) as an enabling electronic technology for many aerospace applications. The Lewis team is focusing on the chemical vapor deposition of the thin, single-crystal SiC films from which devices are fabricated. These films, which are deposited (i.e., epitaxially "grown") on commercial wafers, must consist of a single crystal with very few structural defects so that the derived devices perform satisfactorily and reliably. Working in collaboration (NASA grant) with Professor Pirouz of Case Western Reserve University, we developed a chemical-mechanical polishing (CMP) technique for removing the subsurface polishing damage prior to epitaxial growth of the single-crystal SiC films.

  3. Cation Effect on Copper Chemical Mechanical Polishing

    Institute of Scientific and Technical Information of China (English)

    WANG Liang-Yong; LIU Bo; SONG Zhi-Tang; FENG Song-Lin

    2009-01-01

    We examine the effect of cations in solutions containing benzotriazole (BTA) and H2O2 on copper chemical mechanical polishing (CMP). On the base of atomic force microscopy (AFM) and material removal rate (MRR) results, it is found that ammonia shows the highest MRR as well as good surface after CMP, while KOH demon-strates the worst performance. These results reveal a mechanism that sma//molecules with lone-pairs rather than molecules with steric effect and common inorganic cations are better for copper CMP process, which is indirectly confirmed by open circuit potential (OCP).

  4. Chemical mechanical polishing (CMP) of sapphire

    Science.gov (United States)

    Zhu, Honglin

    The concept of chemical mechanical polishing (CMP) was examined for finishing sapphire. In this study sapphire was used as a model system for oxide ceramics. The removal rates were determined by weight loss. Surface quality and structure were characterized with surface probe microscopy (SPM). Polishing experiments were designed to test the chemically modified surface layer. A series of abrasives with various hardnesses including mono-crystalline and polycrystalline diamond, alpha and gamma alumina, zirconia, ceria and silica were used. Diaspore was also evaluated. The results indicated that, with similar particle size and shape, harder abrasives do not necessarily cause faster material removal and better surface finish, and abrasives with hardness equal to or less than sapphire such as alpha alumina and gamma alumina achieved the best surface finish and efficient material removal. A hypothesis was proposed that the sapphire surface was modified by water to form a thin hydration laver with structure and hardness close to diaspore. Abrasives with a hardness between diaspore and sapphire polished the c-plane of sapphire with good surface finish and efficient removal. SPM indicated the hydration layer on the c-plane surface was about 1 nm thick. Removal rate and surface finish as a function of pH were also examined on c-plane sapphire with nano-alumina abrasives. The removal rate as a function of pH was compared to the solubility behavior of alumina. The results showed the deviation of pH from the lowest solubility pH for alumina (pH = 5) was a driving force for the surface reaction to form a hydration layer. The anisotropy of sapphire strongly affects removal rate and surface quality in CMP. The relationships among orientation. pH and abrasive were studied for sapphire with c (0001), a (11-20), and m (10-10) planes. Based on the results, the CMP process for sapphire includes chemical reaction of the surface to form a thin reaction layer that is softer than sapphire

  5. Defect centers in chemical-mechanical polished MOS oxides

    Energy Technology Data Exchange (ETDEWEB)

    Shaneyfelt, M.R.; Warren, W.L.; Hetherington, D.L.; Timon, R.P.; Resnick, P.J.; Winokur, P.S.

    1994-12-31

    Defect centers generated in vacuum-ultraviolet irradiated chemical-mechanical polished oxides have been characterized using electron paramagnetic resonance and C-V analysis. Both oxide trap E{sub {gamma}} and interface trap P{sub b0} centers were detected in unpolished and polished oxides. In addition, another interface defect center known as the P{sub b1} center was only identified in the polished oxides, suggesting that the polishing process altered the SiO{sub 2}/Si interface.

  6. Effect of Chemicals on Chemical Mechanical Polishing of Glass Substrates

    Institute of Scientific and Technical Information of China (English)

    WANG Liang-Yong; ZHANG Kai-Liang; SONG Zhi-Tang; FENG Song-Lin

    2007-01-01

    @@ We investigate the effect of chemicals on chemical mechanical polishing (CMP) of glass substrates. Ceria slurry in an ultra-low concentration of 0.25wt.% is used and characterized by scanning electron microscopy. Three typical molecules, i.e. acetic acid, citric acid and sodium acrylic polymer, are adopted to investigate the effect on CMP performance in terms of material removal rate (MRR) and surface quality. The addition of sodium acrylic polymer shows the highest MRR as well as the best surface by atomic force microscopy after CMP, vhile the addition of citric acid shows the worst performance. These results reveal a mechanism that a long-chain molecule without any branches rather than small molecules and common molecules with ramose abundant-electron groups is better for the dispersion of the slurry and thus better for the CMP process.

  7. 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

  8. Modeling Chemical Mechanical Polishing with Couple Stress Fluids

    Institute of Scientific and Technical Information of China (English)

    张朝辉; 雒建斌; 温诗铸

    2004-01-01

    Chemical mechanical polishing (CMP) is a manufacturing process used to achieve high levels of global and local planarity.Currently, the slurries used in CMP usually contain nanoscale particles to accelerate the removal ratio and to optimize the planarity, whose rheological properties can no longer be accurately modeled with Newtonian fluids.The Reynolds equation, including the couple stress effects, was derived in this paper.The equation describes the mechanism to solve the CMP lubrication equation with the couple stress effects.The effects on load and moments resulting from the various parameters, such as pivot height, roll angle, and pitch angle, were subsequently simulated.The results show that the couple stress can provide higher load and angular moments.This study sheds some lights into the mechanism of the CMP process.

  9. Application of chemical mechanical polishing process on titanium based implants.

    Science.gov (United States)

    Ozdemir, Z; Ozdemir, A; Basim, G B

    2016-11-01

    Modification of the implantable biomaterial surfaces is known to improve the biocompatibility of metallic implants. Particularly, treatments such as etching, sand-blasting or laser treatment are commonly studied to understand the impact of nano/micro roughness on cell attachment. Although, the currently utilized surface modification techniques are known to improve the amount of cell attachment, it is critical to control the level of attachment due to the fact that promotion of bioactivity is needed for prosthetic implants while the cardiac valves, which are also made of titanium, need demotion of cells attachment to be able to function. In this study, a new alternative is proposed to treat the implantable titanium surfaces by chemical mechanical polishing (CMP) technique. It is demonstrated that the application of CMP on the titanium surface helps in modifying the surface roughness of the implant in a controlled manner (inducing nano-scale smoothness or controlled nano/micro roughness). Simultaneously, it is observed that the application of CMP limits the bacteria growth by forming a protective thin surface oxide layer on titanium implants. It is further shown that there is an optimal level of surface roughness where the cell attachment reaches a maximum and the level of roughness is controllable through CMP. PMID:27524033

  10. Research on the molecular scale material removal mechanism in chemical mechanical polishing

    Institute of Scientific and Technical Information of China (English)

    WANG YongGuang; ZHAO YongWu

    2008-01-01

    This paper investigates a novel molecular scale material removal mechanism in chemical mechanical polishing (CMP) by incorporating the order-of-magnitude calculations,particle adhesion force,defect of wafer,thickness of newly formed oxidizedlayer,and large deformation of pad/particle not discussed by previous analysis.The theoretical analysis and experimental data show that the indentation depth,scratching depth and polishing surface roughness are on the order of molecular scale or less.There.fore,this novel mechanism has gained the support from wide order-of- magnitude calculations and experimental data.In addition,with the decrease in the particle size,the molecular scale removal mechanism is plausibly one of the most promising removal mechanisms to clarify the CMP polishing process.The results are useful to substantiating the molecular-scale mechanism of the CMP material removal in addition to its underlying theoretical foundation.

  11. Chemical mechanical polishing of transparent conductive layers using spherical cationic polymer microbeads

    Energy Technology Data Exchange (ETDEWEB)

    Nagaoka, Shoji, E-mail: nagaoka@kmt-iri.go.jp [Kumamoto Industrial Research Institute, 3-11-38 Higashimachi, Higashiku, Kumamoto 862-0901 (Japan); Department of Applied Chemistry and Biochemistry, Kumamoto University, 2-39-1 Kurokami, Chuouku, Kumamoto 860-8555 (Japan); Kumamoto Institute for Photo-Electro Organics (Phoenics), 3-11-38 Higashimachi, Higashiku, Kumamoto 862-0901 (Japan); Ryu, Naoya [Kumamoto Industrial Research Institute, 3-11-38 Higashimachi, Higashiku, Kumamoto 862-0901 (Japan); Yamanouchi, Akio [Department of Applied Chemistry and Biochemistry, Kumamoto University, 2-39-1 Kurokami, Chuouku, Kumamoto 860-8555 (Japan); Shirosaki, Tomohiro [Kumamoto Industrial Research Institute, 3-11-38 Higashimachi, Higashiku, Kumamoto 862-0901 (Japan); Kumamoto Institute for Photo-Electro Organics (Phoenics), 3-11-38 Higashimachi, Higashiku, Kumamoto 862-0901 (Japan); Horikawa, Maki [Kumamoto Industrial Research Institute, 3-11-38 Higashimachi, Higashiku, Kumamoto 862-0901 (Japan); Department of Applied Chemistry and Biochemistry, Kumamoto University, 2-39-1 Kurokami, Chuouku, Kumamoto 860-8555 (Japan); Kumamoto Institute for Photo-Electro Organics (Phoenics), 3-11-38 Higashimachi, Higashiku, Kumamoto 862-0901 (Japan); Sakurai, Hideo; Takafuji, Makoto; Ihara, Hirotaka [Department of Applied Chemistry and Biochemistry, Kumamoto University, 2-39-1 Kurokami, Chuouku, Kumamoto 860-8555 (Japan); Kumamoto Institute for Photo-Electro Organics (Phoenics), 3-11-38 Higashimachi, Higashiku, Kumamoto 862-0901 (Japan)

    2015-02-02

    Spherical cationic polymer microbeads were used to chemically mechanically polish transparent conductive oxide (TCO) layers without the need for inorganic abrasives. Poly(methyl acrylate) (PMA) was used as the polymer matrix. Surface cationization of the spherical PMA microbeads was achieved by aminolysis using 1,2-diaminoethane. The amino group content of the microbeads was controlled using the aminolysis reaction time. The surface roughness of the TCO polished using the cationic polymer microbeads was similar to that of TCO polished with an inorganic abrasive. The microbead-polished TCO layer was slightly thinner than the unpolished TCO layer. The sheet resistance of the TCO layer polished using the microbeads was lower than that polished using the inorganic abrasive. The TCO polishing ability of the microbeads was dependent on their cationic properties and softness. - Highlights: • Indium tin oxide (ITO) layer was planarized using cationic polymer microbeads. • Cationic polymer microbeads planarized, while retaining ITO layer thickness • Cationic polymer microbeads did not degrade the sheet resistance of ITO. • Cationic polymer microbeads could planarize the ITO surface without damaging.

  12. Chemical mechanical polishing of transparent conductive layers using spherical cationic polymer microbeads

    International Nuclear Information System (INIS)

    Spherical cationic polymer microbeads were used to chemically mechanically polish transparent conductive oxide (TCO) layers without the need for inorganic abrasives. Poly(methyl acrylate) (PMA) was used as the polymer matrix. Surface cationization of the spherical PMA microbeads was achieved by aminolysis using 1,2-diaminoethane. The amino group content of the microbeads was controlled using the aminolysis reaction time. The surface roughness of the TCO polished using the cationic polymer microbeads was similar to that of TCO polished with an inorganic abrasive. The microbead-polished TCO layer was slightly thinner than the unpolished TCO layer. The sheet resistance of the TCO layer polished using the microbeads was lower than that polished using the inorganic abrasive. The TCO polishing ability of the microbeads was dependent on their cationic properties and softness. - Highlights: • Indium tin oxide (ITO) layer was planarized using cationic polymer microbeads. • Cationic polymer microbeads planarized, while retaining ITO layer thickness • Cationic polymer microbeads did not degrade the sheet resistance of ITO. • Cationic polymer microbeads could planarize the ITO surface without damaging

  13. 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.

  14. Damascene Array Structure of Phase Change Memory Fabricated with Chemical Mechanical Polishing Method

    Institute of Scientific and Technical Information of China (English)

    LIU Qi-Bin; SONG Zhi-Tang; ZHANG Kai-Liang; WANG Liang-Yong; FENG Song-Lin; CHEN Bomy

    2006-01-01

    @@ A damascene structure of phase change memory (PCM) is fabricated successfully with the chemical mechanical polishing (CMP) method, and the CMP of Ge2Sb2Te5 (GST) and Ti films is investigated. The polished surface of wafer is analysed by scanning electron microscopy (SEM) and an energy dispersive spectrometer (EDS). The measurements show that the damascene device structure of phase change memory is achieved by the CMP process.After the top electrode is deposited, dc sweeping test on PCM reveals that the phase change can be observed.The threshold current of array cells varies between 0.90mA and 1.15mA.

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

    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)

    2013-11-15

    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

  16. Surface characteristics of ruthenium in periodate-based slurry during chemical mechanical polishing

    Energy Technology Data Exchange (ETDEWEB)

    Cheng, Jie; Wang, Tongqing; Jiang, Liang; Lu, Xinchun, E-mail: xclu@tsinghua.edu.cn

    2015-10-01

    Highlights: • The Ru surface chemical and mechanical property varies with KIO{sub 4} slurry pH. • In alkaline slurry, the corrosion proceeds uniformly like a direct dissolution. • In neutral and acidic slurries, Ru exhibits passivation behavior. • MRR is highest in neutral slurry due to inhomogeneous RuO{sub 2}·2H{sub 2}O/RuO{sub 3} passivation. • Weak alkaline slurry is preferred to get good MRR and avoid toxic RuO{sub 4} formation. - Abstract: When the feature size of integrated circuit continues to shrink below 14 nm, ruthenium (Ru) has become one of the most promising candidates for the application of novel barrier layer. To reveal the material removal mechanism of Ru during chemical mechanical polishing (CMP), surface characteristics of Ru in KIO{sub 4}-based slurry were investigated. The corrosion behavior of ruthenium was measured by the surface chemistry and morphology analysis. Then the mechanical properties of the passivated/corroded surface were evaluated by AES and tribocorrosion experiments. CMP experiments were carried out to make clear the effects of surface property during polishing. It was found that the Ru surface chemistry and mechanical properties vary obviously as a function of slurry pH. In neutral slurries, the Ru surface is covered with RuO{sub 2}·2H{sub 2}O/RuO{sub 3} inhomogeneous passivation films, with the highest material removal rate obtained during the CMP process. It could be concluded that the material removal mechanism largely depends on the slurry pH values. In near neutral slurries, Ru is passivated with thick and heterogeneous oxides film, which proves the easiest to be mechanically removed during polishing. The weak alkaline slurry is preferred in order to achieve desirable polishing rate as well as avoid the formation of toxic RuO{sub 4}.

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

    Science.gov (United States)

    Zhu, Aibin; He, Dayong; Luo, Wencheng; Liu, Yangyang

    2016-11-01

    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.

  18. Chemical Mechanical Polishing of Glass Substrate with α-Alumina-g-Polystyrene Sulfonic Acid Composite Abrasive

    Institute of Scientific and Technical Information of China (English)

    LEI Hong; BU Naijing; ZHANG Zefang; CHEN Ruling

    2010-01-01

    Abrasive is the one of key influencing factors during chemical mechanical polishing(CMP) process. Currently, α-Alumina (α-Al2O3) particle, as a kind of abrasive, has been widely used in CMP slurries, but their high hardness and poor dispersion stability often lead to more surface defects. After being polished with composite particles, the surface defects of work pieces decrease obviously. So the composite particles as abrasives in slurry have been paid more attention. In order to reduce defect caused by pure α-Al2O3 abrasive, α-alumina-g-polystyrene sulfonic acid (α-Al2O3-g-PSS) composite abrasive was prepared by surface graft polymerization. The composition, structure and morphology of the product were characterized by Fourier transform infrared spectroscopy(FTIR), X-ray photoelectron spectroscopy(XPS), time-of-flight secondary ion mass spectroscopy(TOF-SIMS), and scanning electron microscopy(SEM), respectively. The results show that polystyrene sulfonic acid grafts onto α-Al2O3, and has well dispersibility. Then, the chemical mechanical polishing performances of the composite abrasive on glass substrate were investigated with a SPEEDFAM-16B-4M CMP machine. Atomic force microscopy(AFM) images indicate that the average roughness of the polished glass substrate surface can be decreased from 0.835 nm for pure α-Al2O3 abrasive to 0.583 nm for prepared α-Al2O3-g-PSS core-shell abrasive. The research provides a new and effect way to improve the surface qualities during CMP.

  19. Chemical Mechanical Polishing of Ge2Sb2Te5 Using Abrasive-Free Solutions of Iron Trichloride

    Institute of Scientific and Technical Information of China (English)

    YAN Wei-Xia; WANG Liang-Yong; ZHANG Ze-Fang; HE Ao-Dong; ZHONG Min; LIU Wei-Li; WU Liang-Cai; SONG Zhi-Tang

    2012-01-01

    Chemical mechanical polishing (CMP) of amorphous Ge2Sb2Te5 (GST) is studied using aqueous solutions of iron trichloride (FeCl3 ) as possible abrasive-free slurries.The polishing performance of abrasive-free solutions is compared with abrasive-containing (3wt%o colloidal silica) slurry in terms of polishing rate and surface quality.The experimental results indicate that the abrasive-free solutions have a higher polishing rate and better surface quality.In order to further investigate the polishing mechanism,post-CMP GST films using the abrasive-free solutions and abrasive-containing slurry are characterized by x-ray photoelectron spectroscopy. Finally,it is verified that the abrasive-free solutions have no influence on the electrical property of the post-CMP GST films through the resistivity test.

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

    Institute of Scientific and Technical Information of China (English)

    ZHONG Min; SONG Zhi-Tang; LIU Bo; FENG Song-Lin; CHEN Bomy

    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 Ge2Sb2Te5 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,Ge2 Sb2 Te5 material stoichiometric content ratios are unchanged.After the top electrode is deposited,currentvoltage characteristics test demonstrates that the set threshold voltage is reduced from 13 V to 2.7V and the threshold current from 0.1 mA to 0.025 mA.Furthermore,we analyse the RIE cleaning principle and compare it with the ultrasonic method.

  1. Nanotopography Impact in Shallow Trench Isolation Chemical Mechanical Polishing-Dependence on Slurry Characteristics

    Institute of Scientific and Technical Information of China (English)

    Jea-Gun Park; Takeo Katoh; Ungyu Paik

    2004-01-01

    The nanotopography of the surface of silicon wafers has become an important issue in ULSI device manufacturing since it affects the post-chemical mechanical polishing (post-CMP) uniformity of the thickness deviation of dielectric films. In this study, the nanotopography impact was investigated in terms of its dependence on the characteristics of ceriabased slurries, such as the abrasive size, the grain size of the polycrystalline abrasive and the surfactant added to the slurry. It was found that the magnitude of the post-CMP oxide thickness deviation due to nanotopography increased with the surfactant concentration in the case of smaller abrasives but was almost independent of the concentration in the case of larger abrasives. The grain size of the polycrystalline abrasive did not affect the nanotopography impact.

  2. 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.

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

    International Nuclear Information System (INIS)

    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.

  4. Iron trichloride as oxidizer in acid slurry for chemical mechanical polishing of Ge2Sb2Te5

    International Nuclear Information System (INIS)

    The effect of iron trichloride (FeCl3) on chemical mechanical polishing (CMP) of Ge2Sb2Te5 (GST) film is investigated in this paper. The polishing rate of GST increases from 38 nm/min to 144 nm/min when the FeCl3 concentration changes from 0.01 wt% to 0.15 wt%, which is much faster than 20 nm/min for the 1 wt% H2O2-based slurry. This polishing rate trends are inversely correlated with the contact angle data of FeCl3-based slurry on the GST film surface. Thus, it is hypothesized that the hydrophilicity of the GST film surface is associated with the polishing rate during CMP. Atomic force microscope (AFM) and optical microscope (OM) are used to characterize the surface quality after CMP. The chemical mechanism is studied by potentiodynamic measurements such as Ecorr and Icorr to analyze chemical reaction between FeCl3 and GST surface. Finally, it is verified that slurry with FeCl3 has no influence on the electrical property of the post-CMP GST film by the resistivity–temperature (RT) tests. (interdisciplinary physics and related areas of science and technology)

  5. 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.

  6. 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.

  7. Surface modification of ceria nanoparticles and their chemical mechanical polishing behavior on glass substrate

    International Nuclear Information System (INIS)

    To improve their chemical mechanical polishing (CMP) performance, ceria nanoparticles were surface modified with γ-aminopropyltriethoxysilane (APS) through silanization reaction with their surface hydroxyl group. The compositions, structures and dispersibility of the modified ceria particles were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), field-emission scanning electron microscopy (FE-SEM), energy dispersive spectroscopy (EDS), laser particle size analyzer, zeta potential measurement and stability test, respectively. The results indicated that APS had been successfully grafted onto the surface of ceria nanoparticles, which led to the modified ceria nanoparticles with better dispersibility and stability than unmodified ceria particles in aqueous fluids. Then, CMP performance of the modified ceria nanoparticles on glass substrate was investigated. Experimental results showed that the modified ceria particles exhibited lower material removal rate (MRR) but much better surface quality than unmodified ceria particles, which may be explained by the hardness reduction of ceria particles, the enhancement of lubrication of the particles and substrate surfaces, and the elimination of the agglomeration among the ceria particles.

  8. Modeling effects of abrasive particle size and concentration on material removal at molecular scale in chemical mechanical polishing

    International Nuclear Information System (INIS)

    A novel material removal model as a function of abrasive particle size and concentration was established in chemical mechanical polishing (CMP) based on molecular scale mechanism, micro-contact mechanics and probability statistics. A close-form equation was firstly developed to calculate the number of effective particles. It found nonlinear dependences of removal rate on the particle size and concentration, being qualitatively agreement with the published experimental data. The nonlinear relation results from the couple relationship among abrasive number, slurry concentration and surface atoms' binding energy with the particle size. Finally, the system parameters such as the operational conditions and materials properties were incorporated into the model as well.

  9. A novel approach of chemical mechanical polishing using environment-friendly slurry for mercury cadmium telluride semiconductors

    Science.gov (United States)

    Zhang, Zhenyu; Wang, Bo; Zhou, Ping; Guo, Dongming; Kang, Renke; Zhang, Bi

    2016-03-01

    A novel approach of chemical mechanical polishing (CMP) is developed for mercury cadmium telluride (HgCdTe or MCT) semiconductors. Firstly, fixed-abrasive lapping is used to machine the MCT wafers, and the lapping solution is deionized water. Secondly, the MCT wafers are polished using the developed CMP slurry. The CMP slurry consists of mainly SiO2 nanospheres, H2O2, and malic and citric acids, which are different from previous CMP slurries, in which corrosive and toxic chemical reagents are usually employed. Finally, the polished MCT wafers are cleaned and dried by deionized water and compressed air, respectively. The novel approach of CMP is environment-friendly. Surface roughness Ra, and peak-to-valley (PV) values of 0.45, and 4.74 nm are achieved, respectively on MCT wafers after CMP. The first and second passivating processes are observed in electrochemical measurements on MCT wafers. The fundamental mechanisms of CMP are proposed according to the X-ray photoelectron spectroscopy (XPS) and electrochemical measurements. Malic and citric acids dominate the first passivating process, and the CMP slurry governs the second process. Te4+3d peaks are absent after CMP induced by the developed CMP slurry, indicating the removing of oxidized films on MCT wafers, which is difficult to achieve using single H2O2 and malic and citric acids solutions.

  10. Study on the Effect of Nano-SiO2 in ULSI Silicon Substrate Chemical Mechanical Polishing Process

    Directory of Open Access Journals (Sweden)

    Liu Yuling

    2006-01-01

    Full Text Available Both process and mechanical of silicon substrate chemical mechanical polishing (CMP are studied in detail, and the effects of experiments designed indicate that nano-SiO2 grinding particles seem to be acted as catalyzer besides the grinding action during the CMP process. This is different from the traditional function. As a result, in the condition of low pH, the nano-SiO2 slurry can be recycled. In the meanwhile, the removal rate can gain stability and pH value does not change obviously.

  11. 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.

  12. Synthesis and Characterization of SiO2 Nanoparticles and Their Efficacy in Chemical Mechanical Polishing Steel Substrate

    Directory of Open Access Journals (Sweden)

    M. J. Kao

    2014-01-01

    Full Text Available Chemical mechanical polishing (CMP technology is extensively used in the global planarization of highly value-added and large components in the aerospace industry. A nanopowder of SiO2 was prepared by the sol-gel method and was compounded into polishing slurry for the CMP of steel substrate. The size of the SiO2 abrasives was controlled by varying the sol-gel reaction conditions. The polishing efficacy of nano-SiO2 was studied, and the CMP mechanism with nanosized abrasives was further investigated. The proposed methods can produce SiO2 abrasives whose size can be controlled by varying the sol-gel reaction conditions. The size of the SiO2 abrasives was controlled in the range from 58 to 684 nm. The roughness of the steel substrate strongly depends on the size of the abrasive, and the surface roughness decreases as the abrasive size declines. A super-smooth surface with a roughness of 8.4 nm is obtained with nanosized SiO2. Ideal CMP slurry can be used to produce material surfaces with low roughness, excellent global planarization, high selectivity, an excellent finish, and a low-defected rate.

  13. Atomistic Mechanisms of Chemical Mechanical Polishing of a Cu Surface in Aqueous H2O2: Tight-Binding Quantum Chemical Molecular Dynamics Simulations.

    Science.gov (United States)

    Kawaguchi, Kentaro; Ito, Hiroshi; Kuwahara, Takuya; Higuchi, Yuji; Ozawa, Nobuki; Kubo, Momoji

    2016-05-11

    We applied our original chemical mechanical polishing (CMP) simulator based on the tight-binding quantum chemical molecular dynamics (TB-QCMD) method to clarify the atomistic mechanism of CMP processes on a Cu(111) surface polished with a SiO2 abrasive grain in aqueous H2O2. We reveal that the oxidation of the Cu(111) surface mechanically induced at the friction interface is a key process in CMP. In aqueous H2O2, in the first step, OH groups and O atoms adsorbed on a nascent Cu surface are generated by the chemical reactions of H2O2 molecules. In the second step, at the friction interface between the Cu surface and the abrasive grain, the surface-adsorbed O atom intrudes into the Cu bulk and dissociates the Cu-Cu bonds. The dissociation of the Cu-Cu back-bonds raises a Cu atom from the surface that is mechanically sheared by the abrasive grain. In the third step, the raised Cu atom bound to the surface-adsorbed OH groups is removed from the surface by the generation and desorption of a Cu(OH)2 molecule. In contrast, in pure water, there are no geometrical changes in the Cu surface because the H2O molecules do not react with the Cu surface, and the abrasive grain slides smoothly on the planar Cu surface. The comparison between the CMP simulations in aqueous H2O2 and pure water indicates that the intrusion of a surface-adsorbed O atom into the Cu bulk is the most important process for the efficient polishing of the Cu surface because it induces the dissociation of the Cu-Cu bonds and generates raised Cu atoms that are sheared off by the abrasive grain. Furthermore, density functional theory calculations show that the intrusion of the surface-adsorbed O atoms into the Cu bulk has a high activation energy of 28.2 kcal/mol, which is difficult to overcome at 300 K. Thus, we suggest that the intrusion of surface-adsorbed O atoms into the Cu bulk induced by abrasive grains at the friction interface is a rate-determining step in the Cu CMP process. PMID:27092706

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

    Energy Technology Data Exchange (ETDEWEB)

    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); 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); Shi, Xiaolei; Xu, Li; Zou, Chunli; Gong, Hua; Luo, Guihai [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)

    2014-10-15

    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{sub 2}O{sub 2}, but not that after immersing in H{sub 2}O{sub 2} solution. UV–vis spectroscopy curves prove that • OH hydroxyl radical could be generated only under CMP polishing by the slurry including H{sub 2}O{sub 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.

  15. A nano-scale mirror-like surface of Ti-6Al-4V attained by chemical mechanical polishing

    Science.gov (United States)

    Chenliang, Liang; Weili, Liu; Shasha, Li; Hui, Kong; Zefang, Zhang; Zhitang, Song

    2016-05-01

    Metal Ti and its alloys have been widely utilized in the fields of aviation, medical science, and micro-electro-mechanical systems, for its excellent specific strength, resistance to corrosion, and biological compatibility. As the application of Ti moves to the micro or nano scale, however, traditional methods of planarization have shown their short slabs. Thus, we introduce the method of chemical mechanical polishing (CMP) to provide a new way for the nano-scale planarization method of Ti alloys. We obtain a mirror-like surface, whose flatness is of nano-scale, via the CMP method. We test the basic mechanical behavior of Ti-6Al-4V (Ti64) in the CMP process, and optimize the composition of CMP slurry. Furthermore, the possible reactions that may take place in the CMP process have been studied by electrochemical methods combined with x-ray photoelectron spectroscopy (XPS). An equivalent circuit has been built to interpret the dynamic of oxidation. Finally, a model has been established to explain the synergy of chemical and mechanical effects in the CMP of Ti-6Al-4V. Project supported by the National Major Scientific and Technological Special Project during the Twelfth Five-year Plan Period of China (Grant No. 2009ZX02030-1), the National Natural Science Foundation of China (Grant No. 51205387), the Support by Science and Technology Commission of Shanghai City, China (Grant No. 11nm0500300), and the Science and Technology Commission of Shanghai City, China (Grant No. 14XD1425300).

  16. Core/shell composites with polystyrene cores and meso-silica shells as abrasives for improved chemical mechanical polishing behavior

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Yang, E-mail: cy.jpu@126.com; Qin, Jiawei; Wang, Yayun; Li, Zefeng [Changzhou University, School of Material Science and Engineering (China)

    2015-09-15

    The core/shell-structured organic/inorganic composite abrasive has an important potential application in damage-free chemical mechanical polishing (CMP) due to its non-rigid mechanical property. In this work, the PS/{sub M}SiO{sub 2} composites, containing polystyrene (PS) sphere (211 ± 4 nm) cores and mesoporous silica shells (31 ± 3 nm in thickness) were synthesized through directed surface sol–gel process of tetraethylorthosilicate on the polymer cores in the presence of the cetyltrimethylammonium bromide surfactant. For comparison, the conventional core/shell PS/{sub N}SiO{sub 2} composites with non-porous silica shells were also prepared via a modified Stöber procedure that involved the hydrolysis of TEOS under acidic condition. The physical properties of the samples were examined by small-angle X-ray diffraction, fourier transform infrared spectroscopy, thermogravimetric analysis, transmission electron microscopy, field emission scanning electron microscopy, and nitrogen adsorption–desorption. As novel abrasives, the core/shell-structured PS/{sub M}SiO{sub 2} composites were introduced into the CMP process for silicon oxide films. The oxide-CMP performance among conventional solid silica particles, PS/{sub N}SiO{sub 2} composites, and novel PS/{sub M}SiO{sub 2} composites was explored by atomic force microscopy. Polishing results indicated that the substrate revealed a comparable root-mean-square surface roughness (0.25 ± 0.03 and 0.22 ± 0.02 nm, respectively) after CMP with PS/{sub N}SiO{sub 2} and PS/{sub M}SiO{sub 2} abrasives under the same polishing conditions. However, the material removal rate of the PS/{sub M}SiO{sub 2} composites (123 ± 15 nm/min) was about three times larger than that of the PS/{sub N}SiO{sub 2} composites (47 ± 13 nm/min). The reduced surface roughness and improved removal rate might be due to the optimization of the physical and/or chemical environments in the local contacting region between abrasives

  17. Corrosion Investigations of Ruthenium in Potassium Periodate Solutions Relevant for Chemical Mechanical Polishing

    Science.gov (United States)

    Cheng, Jie; Wang, Tongqing; Pan, Jinshan; Lu, Xinchun

    2016-08-01

    Ruthenium is the most promising material for the barrier layer used for the sub 14 nm technology node in integrated circuits manufacturing. Potassium periodate (KIO4)-based slurry is used in the chemical mechanical planarization (CMP) process of the barrier layer. However, the electrochemical and corrosion properties of ruthenium have not been investigated in such slurry. In this paper, the electrochemical and corrosion behaviors of ruthenium in KIO4 solutions were investigated under static conditions but at different pH values by potentiodynamic polarization and electrochemical impedance spectroscopy measurements, combined with surface chemical analysis using auger electron spectroscopy. Moreover, to study wear enhanced corrosion during CMP, tribocorrosion experiments were carried out to monitor the current density changes during and after mechanical scratching. The results show that at pH 6, ruthenium forms a relatively thick and heterogeneous surface film composed of RuO2·2H2O/RuO3, showing a high corrosion resistance and it exhibits a quick repassivation after mechanical scratching. At pH 4, ruthenium shows a passivation behavior with formation of a uniform and conductive oxide like RuO2·2H2O. It should be noted that there is a possible formation of RuO4 toxic gas under this condition, which should be avoided in the actual production. However, at pH 11, ruthenium exhibits no considerable passivity and the corrosion proceeds uniformly.

  18. Chemical mechanical polishing of Indium phosphide, Gallium arsenide and Indium gallium arsenide films and related environment and safety aspects

    Science.gov (United States)

    Matovu, John Bogere

    As scaling continues with advanced technology nodes in the microelectronic industry to enhance device performance, the performance limits of the conventional substrate materials such as silicon as a channel material in the front-end-of-the-line of the complementary metal oxide semiconductor (CMOS) need to be surmounted. These challenges have invigorated research into new materials such as III-V materials consisting of InP, GaAs, InGaAs for n-channel CMOS and Ge for p-channels CMOS to enhance device performance. These III-V materials have higher electron mobility that is required for the n-channel while Ge has high hole mobility that is required for the p-channel. Integration of these materials in future devices requires chemical mechanical polishing (CMP) to achieve a smooth and planar surface to enable further processing. The CMP process of these materials has been associated with environment, health and safety (EH&S) issues due to the presence of P and As that can lead to the formation of toxic gaseous hydrides. The safe handling of As contaminated consumables and post-CMP slurry waste is essential. In this work, the chemical mechanical polishing of InP, GaAs and InGaAs films and the associated environment, health and safety (EH&S) issues are discussed. InP removal rates (RRs) and phosphine generation during the CMP of blanket InP films in hydrogen peroxide-based silica particle dispersions in the presence and absence of three different multifunctional chelating carboxylic acids, namely oxalic acid, tartaric acid, and citric acid are reported. The presence of these acids in the polishing slurry resulted in good InP removal rates (about 400 nm min-1) and very low phosphine generation (surfaces (0.1 nm RMS surface roughness). The optimized slurry compositions consisting of 3 wt % silica, 1 wt % hydrogen peroxide and 0.08 M oxalic acid or citric acid that provided the best results on blanket InP films were used to evaluate their planarization capability of patterned

  19. Preparation of Fe-doped colloidal SiO(2) abrasives and their chemical mechanical polishing behavior on sapphire substrates.

    Science.gov (United States)

    Lei, Hong; Gu, Qian; Chen, Ruling; Wang, Zhanyong

    2015-08-20

    Abrasives are one of key influencing factors on surface quality during chemical mechanical polishing (CMP). Silica sol, a widely used abrasive in CMP slurries for sapphire substrates, often causes lower material removal rate (MRRs). In the present paper, Fe-doped colloidal SiO2 composite abrasives were prepared by a seed-induced growth method in order to improve the MRR of sapphire substrates. The CMP performance of Fe-doped colloidal SiO2 abrasives on sapphire substrates was investigated using UNIPOL-1502 CMP equipment. Experimental results indicate that the Fe-doped colloidal SiO2 composite abrasives exhibit lower surface roughness and higher MRR than pure colloidal SiO2 abrasives for sapphire substrates under the same testing conditions. Furthermore, the acting mechanism of Fe-doped colloidal SiO2 composite abrasives in sapphire CMP was analyzed by x-ray photoelectron spectroscopy. Analytical results show that the Fe in the composite abrasives can react with the sapphire substrates to form aluminum ferrite (AlFeO3) during CMP, which promotes the chemical effect in CMP and leads to improvement of MRR. PMID:26368752

  20. 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.

  1. Research on Abrasives in the Chemical Mechanical Polishing Process for Silicon Nitride Balls

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Silicon nitride (Si 3N 4) has been the main material for balls in ceramic ball bearings, for its lower density, high strength, high hardness, fine thermal stability and anticorrosive, and is widely used in various fields, such as high speed and high temperature areojet engines, precision machine tools and chemical engineer machines. Silicon nitride ceramics is a kind of brittle and hard material that is difficult to machining. In the traditional finishing process of silicon nitride balls, balls are lapped...

  2. 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.

  3. Experimental Study of Chemical Mechanical Rough Polishing for Hard Disk Substrate%硬盘基板化学机械粗抛光的实验研究

    Institute of Scientific and Technical Information of China (English)

    刘利宾; 刘玉岭; 王胜利; 林娜娜; 杨立兵

    2011-01-01

    For rough polishing of NiP/Al substrate of hard disk, SiO2 colloid was adopted to polish the substrate of hard disk under different pressures, speed, pH values, abrasive concentration and activator concentration, the removal rate of hard disk substrate was measured and the surface analyses after chemical mechanical rough polishing were accomplished by atomic force microscope (AFM). Finally, five key polishing parameters were optimized. The results show that when the pressure is 0. 10 Mpa, the speed is 80 rad/min, the pH value is 11.2, the ratio of abrasive volume with the deionized water is 1:0. 5, and surfactant concentration is 9 mL/L, the removal rate of hard disk substrate is 27 mg/min, the surface roughness after polishing is 0.281 nm. After rough polishing of hard disk substrate, high removal rate and good surface roughness are obtained, and it will greatly reduce the time of fine polishing, which is beneficial to increase the polishing efficiency.%针对硬盘NiP/Al基板粗抛光,采用SiO2作为抛光磨料的碱性抛光液,在不同压力、转速、pH值、磨料浓度和活性剂体积浓度下,对硬盘基板粗抛光的去除速率和表面粗糙度的变化规律进行研究,用原子力显微镜观察抛光表面的微观形貌.最后对5个关键参数进行了优化.结果表明:当压力为0.10 MPa,转速为80 rad/min,pH值为11.2,磨料与去离子水体积比为1∶0.5,表面活性剂体积浓度为9 mL/L时,硬盘基板的去除速率为27 mg/min,粗抛后表面粗糙度为0.281 nm,获得了高的去除速率和较好的表面粗糙度,这样会大大降低精抛的时间,有利于抛光效率的提高.

  4. Development of High-Speed Copper Chemical Mechanical Polishing Slurry for Through Silicon Via Application Based on Friction Analysis Using Atomic Force Microscope

    Science.gov (United States)

    Amanokura, Jin; Ono, Hiroshi; Hombo, Kyoko

    2011-05-01

    In order to obtain a high-speed copper chemical mechanical polishing (CMP) process for through silicon vias (TSV) application, we developed a new Cu CMP slurry through friction analysis of Cu reaction layer by an atomic force microscope (AFM) technique. A lateral modulation friction force microscope (LM-FFM) is able to measure the friction value properly giving a vibration to the layer. We evaluated the torsional displacement between the probe of the LM-FFM and the Cu reaction layer under a 5 nm vibration to cancel the shape effect of the Cu reaction layer. The developed Cu CMP slurry forms a frictionally easy-removable Cu reaction layer.

  5. Synergetic effect of benzotriazole and non-ionic surfactant on copper chemical mechanical polishing in KIO{sub 4}-based slurries

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, Liang [State Key Laboratory of Tribology, Tsinghua University, Beijing 100084 (China); Center for Advanced Materials Processing, Clarkson University, Potsdam, NY 13699 (United States); He, Yongyong [State Key Laboratory of Tribology, Tsinghua University, Beijing 100084 (China); Niu, Xiangyu; Li, Yuzhuo [Center for Advanced Materials Processing, Clarkson University, Potsdam, NY 13699 (United States); Luo, Jianbin, E-mail: luojb@tsinghua.edu.cn [State Key Laboratory of Tribology, Tsinghua University, Beijing 100084 (China)

    2014-05-02

    Ruthenium will be integrated into copper interconnects as a barrier layer in the near future. During the chemical mechanical polishing process of the ruthenium barrier layer, copper polishing performance with barrier slurries is crucial to microchips' final performance. This paper mainly studies the synergetic effect of benzotriazole (BTA) and non-ionic surfactant on copper polishing performance using KIO{sub 4}-based barrier slurries. The results show that, the copper removal rate (RR) and static etching rate increase with increasing concentration of KIO{sub 4} due to the increasing proportion of the Cu–periodate and Cu–iodate compounds like Cu(IO{sub 4}){sub 2} and Cu(IO{sub 3}){sub 2} of the passivating film on the copper surface; the added BTA can further enhance the copper RR instead of suppressing it probably due to the formation of incomplete Cu–BTA thin film. It is demonstrated that the combination of BTA and non-ionic surfactant exhibits excellent performance in suppressing the copper RR to about 200 Å/min, realizing satisfactory copper surface quality and achieving desirable material removal rate selectivity among copper, ruthenium and low-κ dielectrics. The synergetic passivation mechanism of BTA and non-ionic surfactant on the copper surface was investigated. It is proposed that in the presence of KIO{sub 4} as an oxidizer, the added BTA and non-ionic surfactant can form a porous passivating film on the copper surface which is mainly composed of the Cu–BTA complex, the adsorbed non-ionic surfactant and the leftover insoluble copper compounds like Cu(IO{sub 4}){sub 2} and Cu(IO{sub 3}){sub 2}, and then the hydrophobic polypropylene oxide segments of non-ionic surfactant can be effectively absorbed on the hydrophobic Cu–BTA complex as a supplement. The above two parts are integrated into a complete passivating film to protect the copper surface from chemical dissolution and excessive mechanical abrasion. - Highlights: • The copper

  6. Atomic-scale and pit-free flattening of GaN by combination of plasma pretreatment and time-controlled chemical mechanical polishing

    Energy Technology Data Exchange (ETDEWEB)

    Deng, Hui; Endo, Katsuyoshi; Yamamura, Kazuya, E-mail: yamamura@upst.eng.osaka-u.ac.jp [Research Center for Ultra-precision Science and Technology, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871 (Japan)

    2015-08-03

    Chemical mechanical polishing (CMP) combined with atmospheric-pressure plasma pretreatment was applied to a GaN (0001) substrate. The irradiation of a CF{sub 4}-containing plasma was proven to be very useful for modifying the surface of GaN. When CMP was conducted on a plasma-irradiated surface, a modified layer of GaF{sub 3} acted as a protective layer on GaN by preventing the formation of etch pits. Within a short duration (8 min) of CMP using a commercially available CeO{sub 2} slurry, an atomically flat surface with a root mean square (rms) roughness of 0.11 nm was obtained. Moreover, etch pits, which are inevitably introduced in conventional CMP, could not be observed at the dislocation sites on the polished GaN surface. It was revealed that CMP combined with the plasma pretreatment was very effective for obtaining a pit-free and atomically flat GaN surface.

  7. Nano-scale stick-slip friction model for the chatter scratch generated by chemical mechanical polishing process.

    Science.gov (United States)

    Kim, Hong Jin; Yang, Ji Chul; Yoon, Bo Un; Lee, Hyeon-Deok; Kim, Taesung

    2012-07-01

    Although Chemical Mechanical Planarization (CMP) process is a still promising technology for the fabrication of the next generation devices, CMP-induced defects tackle further development of CMP process. In particular, even nano-sized scratches generated by CMP process kill the device directly. However mechanism of scratch formation was not clearly understood yet. CMP-induced scratches are classified as razor, chatter mark and skipping scratch. Among them, chatter mark scratch (or chatter scratch) is the most critical defect for the device yield loss. Chatter scratch has a periodic pattern of scars, which is reminiscent of a stick-slip friction pattern. Based on that similarity, stick-slip model was proposed in this paper in order to explain how chatter scratch is formed. And controlling parameters for chatter scratch are defined. During stick period the friction force that exceeds the yield strength of wafer surface makes chatter scratch and the distance between chatter marks is determined by slip period.

  8. Study of impurity distribution in mechanically polished, chemically treated and ultra-high vacuum degassed pure Niobium samples using TOFSIMS technique

    CERN Document Server

    Bose, A

    2015-01-01

    The performance of Superconducting radio frequency cavities (SCRF) are highly dependent on the surface treatment processes, which in turn is influenced by the chemistry within the penetration depth of Niobium (Nb). The present study analyses various impurities within the RF penetration depth (~50nm) of Nb samples treated by SCRF cavity processing techniques like colloidal silica polishing (simulating centrifugal barrel polishing), buffer chemical polishing (BCP), high pressure rinsing (HPR) and degassing under ultra high vacuum (UHV) condition at 600{\\deg}C for 10hrs. Various modes of Time of flight secondary ion mass spectrometry (TOFSIMS) technique was employed to study the effect of the above treatments on the vast spectrum of impurities that include interstitials, hydrocarbons, oxides, acidic residuals, reaction products and metallic impurities. UHV degassing treatment was the only treatment capable of reducing hydrogen contamination, but, it led to extensive oxygen, carbon and metallic impurities in the ...

  9. A facile chemical-mechanical polishing lift-off transfer process toward large scale Cu(In,Ga)Se2 thin-film solar cells on arbitrary substrates

    Science.gov (United States)

    Tseng, Kuan-Chun; Yen, Yu-Ting; Thomas, Stuart R.; Tsai, Hung-Wei; Hsu, Cheng-Hung; Tsai, Wen-Chi; Shen, Chang-Hong; Shieh, Jia-Min; Wang, Zhiming M.; Chueh, Yu-Lun

    2016-02-01

    The fabrication of Cu(In,Ga)Se2 (CIGS) solar cells on flexible substrates is a non-trivial task due to thermal and ion diffusion related issues. In order to circumvent these issues, we have developed a chemical-mechanical polishing lift-off (CMPL) transfer process, enabling the direct transfer of CIGS solar cells from conventional soda-lime glass (SLG) onto arbitrary flexible substrates up to 4 cm2 in size. The structural and compositional nature of the pre- and post-transferred films is examined using electron microscopy, X-ray diffraction analysis, Raman and photoluminescence spectroscopy. We demonstrate the fabrication of solar cells on a range of flexible substrates while being able to maintain 75% cell efficiency (η) when compared to pre-transferred solar cells. The results obtained in this work suggest that our transfer process offers a highly promising approach toward large scale fabrication of CIGS-based solar cells on a wide variety of flexible substrates, suitable for use in the large scale CIGS photovoltaic industry.The fabrication of Cu(In,Ga)Se2 (CIGS) solar cells on flexible substrates is a non-trivial task due to thermal and ion diffusion related issues. In order to circumvent these issues, we have developed a chemical-mechanical polishing lift-off (CMPL) transfer process, enabling the direct transfer of CIGS solar cells from conventional soda-lime glass (SLG) onto arbitrary flexible substrates up to 4 cm2 in size. The structural and compositional nature of the pre- and post-transferred films is examined using electron microscopy, X-ray diffraction analysis, Raman and photoluminescence spectroscopy. We demonstrate the fabrication of solar cells on a range of flexible substrates while being able to maintain 75% cell efficiency (η) when compared to pre-transferred solar cells. The results obtained in this work suggest that our transfer process offers a highly promising approach toward large scale fabrication of CIGS-based solar cells on a wide

  10. Electrolyte composition and removal mechanism of Cu electrochemical mechanical polishing

    Institute of Scientific and Technical Information of China (English)

    边燕飞; 翟文杰; 程媛媛; 朱宝全; 王金虎

    2014-01-01

    The optimization of electrolytes and the material removal mechanisms for Cu electrochemical mechanical planarization (ECMP) at different pH values including 5-methyl-1H-benzotriazole (TTA), hydroxyethylidenediphosphoric acid (HEDP), and tribasic ammonium citrate (TAC) were investigated by electrochemical techniques, X-ray photoelectron spectrometer (XPS) analysis, nano-scratch tests, AFM measurements, and polishing of Cu-coated blanket wafers. The experimental results show that the planarization efficiency and the surface quality after ECMP obtained in alkali-based solutions are superior to that in acidic-based solutions, especially at pH=8. The optimal electrolyte compositions (mass fraction) are 6% HEDP, 0.3% TTA and 3% TAC at pH=8. The main factor affecting the thickness of the oxide layer formed during ECMP process is the applied potential. The soft layer formation is a major mechanism for electrochemical enhanced mechanical abrasion. The surface topography evolution before and after electrochemical polishing (ECP) illustrates the mechanism of mechanical abrasion accelerating electrochemical dissolution, that is, the residual stress caused by the mechanical wear enhances the electrochemical dissolution rate. This understanding is beneficial for optimization of ECMP processes.

  11. Chemical mechanical polishing for silicon wafer by composite abrasive slurry%利用复合磨粒抛光液的硅片化学机械抛光

    Institute of Scientific and Technical Information of China (English)

    许雪峰; 马冰迅; 黄亦申; 彭伟

    2009-01-01

    为了提高硅片的抛光速率,利用复合磨粒抛光液对硅片进行化学机械抛光.分析了SiO2磨粒与聚苯乙烯粒子在溶液中的ζ电位及粒子间的相互作用机制,观察到SiO2磨粒吸附在聚苯乙烯及某种氨基树脂粒子表面的现象.通过向单一磨粒抛光液中加入聚合物粒子的方法获得了复合磨粒抛光液.对硅片传统化学机械抛光与利用复合磨粒抛光液的化学机械抛光进行了抛光性能研究,提出了利用复合磨粒抛光液的化学机械抛光技术的材料去除机理,并分析了抛光工艺参数对抛光速率的影响.实验结果显示,利用单一SiO2磨料抛光液对硅片进行抛光的抛光速率为180 nm/min;利用SiO2磨料与聚苯乙烯粒子或某氨基树脂粒子形成的复合磨粒抛光液对硅片进行抛光的抛光速率分别为273 nm/min和324 nm/min.结果表明,利用复合磨粒抛光液对硅片进行抛光提高了抛光速率,并可获得Ra为0.2 nm的光滑表面.%In order to increase the polishing rate for a silicon wafer,the composite abrasive slurry was used in Chemical Mechanical Polishing(CMP). Zeta potentials of silica abrasives and polystyrene particles in the slurry were measured at various pH values, and the mechanism of interactions between silica abrasives and polymer particles was analyzed. Small silica abrasives were observed to attach onto the surfaces of the polystyrene particles and some resin particles.Then,the composite abrasive slurry was obtained by adding some polymer particles into single abrasive slurry. In comparison with the polishing performance of traditional CMP and CMP using composite abrasive slurry, the mechanism of material removal of CMP using composite abrasive slurry was proposed, and the influence of craft parameters on the polishing rate was studied through the experiments. Experimental results indicate that the polishing rate is 180 nm/min with single silica abrasive slurry, and 273 nm/min, 324 nm

  12. Effect of FA/O complexing agents and H2O2 on chemical mechanical polishing of ruthenium in weakly alkaline slurry

    Science.gov (United States)

    Bo, Duan; Weijing, An; Jianwei, Zhou; Shuai, Wang

    2015-07-01

    This paper investigated the effect of FA/O and hydrogen peroxide (H2O2) on ruthenium (Ru) removal rate (RR) and static etching rate (SER). It was revealed that Ru RR and SER first linearly increased then slowly decreaseed with the increasing H2O2 probably due to the formation of uniform Ru oxides on the surface during polishing. Their corrosion behaviors and states of surface oxidation were analyzed. In addition, FA/O could chelate Ru oxides (such as (RuO4)2- and RuO4- changed into soluble amine salts [R(NH3)4] (RuO4)2) and enhance Ru RR. The non-ionic surfactant AD was used to improve the Ru CMP performance. In particular, the addition of AD can lead to significant improvement of the surface roughness. Project supported by the Special Project Items No. 2 in National Long-Term Technology Development Plan (No. 2009ZX02308), the Natural Science Foundation of Hebei Province (No. E2013202247), the Science and Technology Plan Project of Hebei Province (Nos. Z2010112, 10213936), the Hebei Provincial Department of Education Fund (No. 2011128), and the Scientific Research Fund of Hebei Provincial Education (No. QN2014208).

  13. 钨的化学机械抛光过程中TiN-W电偶的腐蚀行为%Galvanic Corrosion of TiN-W Electro-couple During Tungsten Chemical Mechanical Polishing

    Institute of Scientific and Technical Information of China (English)

    程璇; 林昌健

    2001-01-01

    Chemical-mechanical polishing (CMP) is a process whereby mechanical and chemical forces are combined to remove material from a wafer and polish it to a flat surface. Tungsten CMP is an important process to gain the global planarity of silicon wafers with tungsten (W) plugs. Tungsten is actually deposited on a thin adhesive layer of titanium nitride (TiN) on silicon. When close to the final stage of polishing, TiN and W will be simultaneously exposed to the polishing chemistry, forming a galvanic couple. The corrosion of TiN and W couple will result in different polish rate.   This work studied the potential difference and galvanic currents on particulate contamination of the abrasive on the patterned surface and on corrosion behaviors of TiN and W. The polarization curves of TiN and W were, respectively, obtained in 0.01 mol/L KNO3 solutions in the absence and presence of three typical oxidants (H2O2, KIO3, Fe(NO3)3) by DC polarization technique. The corrosion potentials and galvanic currents were measured when TiN and W were placed in a specially designed electrochemical cell to form electro-couple. The preliminary results revealed that the corrosion rate of TiN-W electro-couple significantly increased in the presence of 4.5% H2O2 at pH 4.0, while reduced to the minimal in the presence of Fe(NO3)3 at pH 1.5. Agitation significantly enhanced the corrosion rate of TiN-W couple.%化学机械抛光(CMP)技术是同时利用化学和机械作用来获得固体表面亚微米尺度上平整性非常有效的方法,从90年代初期起已成为制备高质量镜头和镜面及集成电路制造过程中硅片表面预处理工艺中最常用的技术之一.钨的化学机械抛光是用钨坯获得硅片球面平整度的重要工艺.其过程实际上是先将钨沉积到硅上已有的薄粘附层-氮化钛上,然后进行化学机械抛光.当抛光阶段接近终了时,氮化钛和钨表面将同时暴露在化学抛光液中形成电偶对,并在界

  14. Pulse Electromagnetic Field-assisted Chemical Mechanical Polishing Utilizing Magnetic Composite Abrasives Slurry and Its Polishing Performance%脉冲磁场辅助磁性复合磨粒化学机械抛光技术及其加工试验研究

    Institute of Scientific and Technical Information of China (English)

    黄亦申; 赵彬善; 黄水泉; 游红武; 许雪峰

    2014-01-01

    A polishing method assisted by an auxiliary pulse electromagnetic field was proposed, where the magnetic polymer microspheres/SiO2 composite abrasives were anchored on a smooth glass tool plate by the magnetic force,and the dependence between diameter of composite abrasives and morphology of tool plate was reduced.In polishing processes,the abrasives entered into the polishing area easily by mean of pulse electromagnetic force,and a high material removal rate was obtained.An electromagnet with contrapuntal structure was designed,and simulation calculations show that uni-form distributions of magnetic flux density and electromagnetic force are achieved.Force analyses in-dicate that the electromagnetic force can help the magnetic polymer microspheres enter the polishing area from near-polishing area,and material is polished by magnetic composite abrasives in two-body abrasion wear mechanism.Owing to the pulse electromagnetic force,magnetic composite abrasives is deposited and entered into polishing area easily without the occurrence of magnetic abrasives aggrega-tion.Experiments of polishing silica wafer,using a glass tool plate of Ra 1.1μm surface roughness and pulse electromagnetic field with a certain frequency and duty cycle,have shown the superior char-acteristics.The material removal rate is increased from 137 nm/min to 288 nm/min with the assis-tance of the electromagnetic field of 5 Hz frequency and 50% duty cycle,and the surface roughness of wafer is decreased from Ra 405 nm to Ra 0.641 nm.%提出一种脉冲磁场辅助新型磁性复合磨粒化学机械抛光技术。该技术利用磁性聚合物微球与Si O 2磨粒组成的复合磨粒抛光液,在脉冲磁场辅助作用下,实现磨粒尺寸对硬质抛光盘微观形貌依赖性小、磨粒易进入抛光区域、材料去除率较高的抛光。设计了“之暠字形的对位式结构电磁铁,模拟计算表明其磁感应强度沿抛光平面分布均匀,磁性微球受到的磁力一致性

  15. Compound Processing Technique for Single Crystal Diamond with Mechanical Lapping and Chemically Assisted Mechanical Polishing%单晶金刚石机械研磨结合化学辅助机械抛光组合加工工艺

    Institute of Scientific and Technical Information of China (English)

    李强; 金洙吉; 苑泽伟; 李伟思; 郭东明

    2013-01-01

    Single crystal diamond is often used to be made into ultra-precise cutting tool for its highest hardness and lowest friction coefficient.Surface roughness is an important requirement for tool life.This paper presents a method for processing single crystal diamond,which integrates mechanical lapping with chemically assisted mechanical polishing.The optimized processing is to first obtain a plane by lapping using 5 μm and 2 μm diamond powders and then remove the damage caused by lapping with chemically assisted mechanical polishing.A surface roughness,Ra =0.8 nm (measured area 70 μm × 53 μm),can be achieved by using this machining process.Moreover,the analysis results with Raman spectrometer indicate that a surface with only 1 332 cm-1 Raman peak can be obtained using chemically assisted mechanical polishing.%单晶金刚石因具有最高的硬度和最低的摩擦系数常被用来制备超精密刀具,而表面粗糙度是影响刀具寿命的重要指标.提出采用机械研磨结合化学辅助机械抛光的组合工艺抛光单晶金刚石.实验优化并确定的加工工艺如下:先用5 μm和2μm金刚石粉研磨单晶金刚石表面,然后采用化学机械的方法去除机械研磨带来的损伤.用该工艺抛光单晶金刚石,表面粗糙度Ra可达0.8 nm(测量区域70 μm×53 μm).表面拉曼光谱分析表明化学机械抛光的表面只有1 332 cm-1拉曼峰.

  16. Summaries of the 40. Scientific Assembly of Polish Chemical Society and Association of Engineers and Technicians of Chemical Industry

    International Nuclear Information System (INIS)

    Annual 40. Scientific Assembly of Polish Chemical Society and Association of Engineers and Technicians of Chemical Industry has been held in Gdansk on 22-26 September 1997. The most valuable scientific results obtained in Polish Laboratories have been presented in 22 main sections and 7 symposia directed especially at following subjects: analytical chemistry, biochemistry, solid state chemistry and material science, physical chemistry, heteroorganic and coordination chemistry, medical and pharmaceutical chemistry, metalorganic chemistry, inorganic and organic chemistry, polymers chemistry, chemistry and environment protection, theoretical chemistry, chemical didactics, photochemistry, radiation chemistry and chemical kinetics, chemical engineering, catalysis, crystallochemistry, chemical technology, electrochemistry, and instrumental methods

  17. Materials of 44. Scientific Assembly of Polish Chemical Society and Association of Engineers and Technicians of Chemical Industry

    International Nuclear Information System (INIS)

    Scientific assemblies of Polish Chemical Society and Association of Engineers and Technicians of Chemical Industry are the most important chemical meeting organised annually in Poland. Basic as well as application studies in all chemical branches have been extensively presented. The next subjects was proposed as scientific sessions and symposia topics: solid state chemistry; didactics of chemistry; electrochemistry; biologically active compounds; geochemistry; organic chemistry; physical chemistry; environment quality and protection; coordination chemistry; chemical technology; polymers; explosive materials; analytical chemistry; theoretical chemistry

  18. Electrochemical and mechanical polishing and shaping method and system

    Science.gov (United States)

    Engelhaupt, Darell E. (Inventor); Gubarev, Mikhail V. (Inventor); Jones, William David (Inventor); Ramsey, Brian D. (Inventor); Benson, Carl M. (Inventor)

    2011-01-01

    A method and system are provided for the shaping and polishing of the surface of a material selected from the group consisting of electrically semi-conductive materials and conductive materials. An electrically non-conductive polishing lap incorporates a conductive electrode such that, when the polishing lap is placed on the material's surface, the electrode is placed in spaced-apart juxtaposition with respect to the material's surface. A liquid electrolyte is disposed between the material's surface and the electrode. The electrolyte has an electrochemical stability constant such that cathodic material deposition on the electrode is not supported when a current flows through the electrode, the electrolyte and the material. As the polishing lap and the material surface experience relative movement, current flows through the electrode based on (i) adherence to Faraday's Law, and (ii) a pre-processing profile of the surface and a desired post-processing profile of the surface.

  19. Evaluation of hardness and color stability in the soft lining materials after thermocycling and chemical polishing.

    Science.gov (United States)

    Goiato, Marcelo Coelho; Falcón-Antenucci, Rosse Mary; Santos, Daniela Micheline dos; Pellizzer, Eduardo Piza

    2009-01-01

    The aim of this study was to evaluate the Shore A hardness and color stability of two soft lining materials after thermocycling and when chemical polishing was used or omitted. Two acrylic-based soft lining materials were tested: Coe-Soft and Soft Confort, 14 specimens were made for each material. They were distributed in four groups according to the treatment performed. The specimens were thermocycled (1000 cycles) and half of the group submitted to chemical polishing (methyl methacrylate). Shore A hardness was determined and color stability was calculated by means of Commission International de l'Eclairage Lab uniform color scale using a spectrophotometer, the measurements were made immediately after deflasked, chemical polishing and thermocycling. Analysis of variance (ANOVA) and Tukey's tests were performed at p Confort (10.60) showed significantly higher values than Coe-Soft (4.57). Coe-Soft (26.42) showed higher Shore A hardness values than Soft Confort (19.42). Chemical polishing did not influence in the color stability of both materials; however, influenced in the hardness values of Coe-Soft. PMID:19601498

  20. Evaluation of hardness and color stability in the soft lining materials after thermocycling and chemical polishing.

    Science.gov (United States)

    Goiato, Marcelo Coelho; Falcón-Antenucci, Rosse Mary; Santos, Daniela Micheline dos; Pellizzer, Eduardo Piza

    2009-01-01

    The aim of this study was to evaluate the Shore A hardness and color stability of two soft lining materials after thermocycling and when chemical polishing was used or omitted. Two acrylic-based soft lining materials were tested: Coe-Soft and Soft Confort, 14 specimens were made for each material. They were distributed in four groups according to the treatment performed. The specimens were thermocycled (1000 cycles) and half of the group submitted to chemical polishing (methyl methacrylate). Shore A hardness was determined and color stability was calculated by means of Commission International de l'Eclairage Lab uniform color scale using a spectrophotometer, the measurements were made immediately after deflasked, chemical polishing and thermocycling. Analysis of variance (ANOVA) and Tukey's tests were performed at p Confort (10.60) showed significantly higher values than Coe-Soft (4.57). Coe-Soft (26.42) showed higher Shore A hardness values than Soft Confort (19.42). Chemical polishing did not influence in the color stability of both materials; however, influenced in the hardness values of Coe-Soft.

  1. Efficacy of chemical treatments in eliminating Salmonella and Escherichia coli O157:H7 on scarified and polished alfalfa seeds.

    Science.gov (United States)

    Holliday, S L; Scouten, A J; Beuchat, L R

    2001-10-01

    Alfalfa seeds are sometimes subjected to a scarification treatment to enhance water uptake, which results in more rapid and uniform germination during sprout production. It has been hypothesized that this mechanical abrasion treatment diminishes the efficacy of chemical treatments used to kill or remove pathogenic bacteria from seeds. A study was done to compare the effectiveness of chlorine (20,000 ppm), H2O, (8%), Ca(OH)2 (1%), Ca(OH)2 (1%) plus Tween 80 (1%), and Ca(OH)2 (1%) plus Span 20 (1%) treatments in killing Salmonella and Escherichia coli O157:H7 inoculated onto control, scarified, and polished alfalfa seeds obtained from two suppliers. The influence of the presence of organic material in the inoculum carrier on the efficacy of sanitizers was investigated. Overall, treatment with 1% Ca(OH)2 was the most effective in reducing populations of the pathogens. Reduction in populations of pathogens on seeds obtained from supplier I indicate that chemical treatments are less efficacious in eliminating the pathogens on scarified seeds compared to control seeds. However, the effectiveness of chemical treatment in removing Salmonella and E. coli O157:H7 from seeds obtained from supplier 2 was not markedly affected by scarification or polishing. The presence of organic material in the inoculum carrier did not have a marked influence on the efficacy of chemicals in reducing populations of test pathogens. Additional lots of control, scarified, and polished alfalfa seeds of additional varieties need to be tested before conclusions can be drawn concerning the impact of mechanical abrasion on the efficacy of chemical treatment in removing or killing Salmonella and E. coli O157:H7. PMID:11601695

  2. Surface topography in mechanical polishing of 6H-SiC (0001) substrate

    Science.gov (United States)

    Yin, Ling; Huang, Han

    2007-12-01

    Silicon carbide (SiC) single crystals have been used as the substrates of a new generation of wide band-gap semiconductors due to their unparalleled combination of high breakdown voltage, extreme temperature tolerance, mobility and radiation hardness. For their applications, the SiC substrates need to be machined with nanometric surface quality as well as high form accuracy. However, the superior properties of the materials render their machinability extremely difficult. In this paper, we report the form error and surface roughness of the 6H-SiC (0001) substrate mechanically polished using 3 μm diamond powders in two different polishing processes. One process was concentrated-load polishing; the other was surface polishing. The polished surfaces were evaluated using white light interferometry and atomic force microscopy (AFM) for assessment of two- and three-dimensional topographies including form error and surface roughness. We found that a large form error was produced on the 6H-SiC (0001) substrate in the concentrated-load polishing. The root-mean-square (RMS) surface roughness of approximately 4 nm was resulted. Surface polishing of the 6H-SiC (0001) substrate remarkably improved form accuracy. The RMS surface roughness of approximately 2.5 nm was obtained.

  3. Development of polishing methods for Chemical Vapor Deposited Silicon Carbide mirrors for synchrotron radiation

    International Nuclear Information System (INIS)

    Material properties of Chemical Vapor Deposited Silicon Carbide (CVD SiC) make it ideal for use in mirrors for synchrotron radiation experiments. We developed methods to grind and polish flat samples of CVD SiC down to measured surface roughness values as low as 1.1 Angstroms rms. We describe the processing details, including observations we made during trial runs with alternative processing recipes. We conclude that pitch polishing using progressively finer diamond abrasive, augmented with specific water based lubricants and additives, produces superior results. Using methods based on these results, a cylindrical and a toroidal mirror, each about 100 x 300mm, were respectively finished by Continental Optical and Frank Cooke, Incorporated. WYCO Interferometry shows these mirrors have surface roughness less than 5.7 Angstroms rms. These mirrors have been installed on the LLNL/UC X-ray Calibration and Standards Facility at the Stanford Synthrotron Radiation Laboratory

  4. Voltage-induced material removal mechanism of copper for electrochemical-mechanical polishing applications

    Institute of Scientific and Technical Information of China (English)

    Sang-Jun HAN; Yong-Jin SEO

    2009-01-01

    The current-voltage (Ⅰ-Ⅴ) curves, such as linear sweep voltammetry (LSV) and cyclic voltammetry (CV), were employed to evaluate the effect of electrolyte concentration on the electrochemical reaction trend. From the Ⅰ-Ⅴ curve, the electrochemical states of active, passive, transient and trans-passive region could be characterized. And then, the mechanism of the process of voltage-induced material removal in electrochemical mechanical polishing (ECMP) of copper was investigated. Scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) analyses were used to observe the surface profile. Finally, the oxidation and reduction processes of the Cu surface were monitored by the repetition of anodic and cathodic potential from cyclic voltammetry (CV) method in acid- and alkali-based electrolyte.

  5. 抛光垫特性及其对300 mm晶圆铜化学机械抛光效果的影响研究%Comparison of Polishing Pad Characteristics in Copper-interconnect Chemical Mechanical Polishing of 300 mm Wafer

    Institute of Scientific and Technical Information of China (English)

    王同庆; 韩桂全; 赵德文; 何永勇; 路新春

    2013-01-01

    利用扫描电子显微镜和接触式表面形貌仪分析了IC1000/Suba-Ⅳ和IC1010两种商用抛光垫的主要特性,并通过自行研制的超低压力化学机械抛光(CMP)试验机、四探针测试仪和三维白光干涉仪等研究了这两种抛光垫对300 mm晶圆铜互连的CMP材料去除率、片内非均匀性、碟形凹陷和腐蚀的影响规律.结果表明:IC1010比IC1000的硬度低、压缩率高、粗糙度大,IC1000为网格状沟槽、沟槽较宽、分布较稀,IC1010为同心圆沟槽、沟槽较细、分布较密;相同条件下IC1010比IC1000的材料去除率大、片内非均匀性好;在相同线宽下IC1000与IC1010的腐蚀几乎一致,IC1010的碟形凹陷比IC1000的略大.%A systematic study of Cu CMP for 300mm wafer in terms of the effect of polishing pad properties on the process characteristics has been performed.The properties of 1C1000/Suba-Ⅳ and IC1010 polishing pads (hardness,compressibility,porosity,roughness and groove) were investigated by scanning electron microscope and stylus profile.The results show that there were significantly differences in the properties of the ICl000/Suba-Ⅳ and IC1010 pads.The IC1000/Suba-Ⅳ and IC1010 polishing pads were compared with regard to the material removal rate,non-uniformity,dishing and erosion of the CMP process for 300 mm wafer.Polishing with the IC1010 pad,a higher material removal rate,better uniformity and worse dishing were achieved.No differences in the pad influence on the erosion have been found.

  6. Chemical Mechanical Planarization (CMP) for Microelectronic Applications

    Institute of Scientific and Technical Information of China (English)

    Li Yuzhuo

    2004-01-01

    Surface planarity is of paramount importance in microelectronics. Chemical Mechanical Polishing (CMP) is the most viable approach to address the planarity issues during the fabrication of advanced semiconductor devices. With the integration of copper as interconnect and low k materials as dielectric, the CMP community is facing an ever increasing demand on reducing defectivity without scarifying production throughput. Key issues in CMP today include reduction of surface defectivity and enhancement of planarization efficiency. More specifically, the polished surface should be free of defects such as scratches, pits, corrosion spots, and residue particles. To accomplish these goals, we have investigated a wide range of pathways including reduction of oversized particles,use of unique abrasives such as functionalized nanoparticles, and development of polishing solution without abrasive particles.In this presentation, some fundamental aspects of the CMP process will be given first.Several academic and industrial examples will be used to illustrate the issues and challenges during the implementation of various slurry designs into the CMP processes.

  7. Colloid Aspects of Chemical-Mechanical Planarization

    Directory of Open Access Journals (Sweden)

    Matijević, E.

    2010-09-01

    Full Text Available The essential parts of interconnects for silicon based logic and memory devices consist of metal wiring (e.g. copper, a barrier metal (Ta, TaN, and of insulation (SiO2 , low-k polymer. The deposition of the conducting metal cannot be confined to trenches, resulting in additional coverage of Cu and Ta/TaN on the surface of the dielectrics, yielding an electrically conducting continuous but an uneven surface. The surplus metal must be removed until a perfectly flat surface consisting of electrically isolated metal lines is achieved with no imperfections. This task is accomplished by the chemical-mechanical planarization (CMP process, in which the wafer is polished with a slurry containing abrasives of finely dispersed particles in submicrometer to nanometer size. The slurries also contain dissolved chemicals to modify the surfaces to be planarized. Eventually the final product must be cleared of any adhered particles and debris left after polishing is completed. Obviously the entire process deals with materials and interactions which are the focal subjects of colloid and surface science, such as the natures of abrasive particles and their stability in the slurry, the properties of various surfaces and their modifications, adhesion and detachment of the particles and different methods for the characterization of constituents, as well as elucidation of the relevant interfacial phenomena. This review endeavors to describe the colloid approach to optimize the materials and processes in order to achieve desirable polish rates and final surfaces with no imperfections. Specifically, the effects of the composition, size, shape, and charge of abrasive particles on the polish process and the quality of planarized wafers is described in detail. Furthermore, the interactions of metal surfaces with oxidizing, chelating, and other species which affect the dissolution and surface modification of metal (copper surfaces are illustrated and related to the

  8. Laser polishing of niobium for SRF applications

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Liang; Klopf, J. Michael [JLAB; Reece, Charles E. [JLAB; Kelley, Michael [W& M

    2013-09-01

    Smooth interior surfaces are desired for niobium SRF cavities, now obtained by buffered chemical polish (BCP) and/or electropolish (EP). Laser polishing is a potential alternative, having advantages of speed, freedom from chemistry and in-process inspection. Here we show that laser polishing can produce smooth topography with Power Spectral Density (PSD) measurements similar to that obtained by EP. We studied the influence of the laser power density and laser beam raster rate on the surface topography. These two factors need to be combined carefully to smooth the surface without damaging it. Computational modeling was used to simulate the surface temperature and explain the mechanism of laser polishing.

  9. Polish Society of Endocrinology Position statement on endocrine disrupting chemicals (EDCs).

    Science.gov (United States)

    Rutkowska, Aleksandra; Rachoń, Dominik; Milewicz, Andrzej; Ruchała, Marek; Bolanowski, Marek; Jędrzejuk, Diana; Bednarczuk, Tomasz; Górska, Maria; Hubalewska-Dydejczyk, Alicja; Kos-Kudła, Beata; Lewiński, Andrzej; Zgliczyński, Wojciech

    2015-01-01

    With the reference to the position statements of the Endocrine Society, the Paediatric Endocrine Society, and the European Society of Paediatric Endocrinology, the Polish Society of Endocrinology points out the adverse health effects caused by endocrine disrupting chemicals (EDCs) commonly used in daily life as components of plastics, food containers, pharmaceuticals, and cosmetics. The statement is based on the alarming data about the increase of the prevalence of many endocrine disorders such as: cryptorchidism, precocious puberty in girls and boys, and hormone-dependent cancers (endometrium, breast, prostate). In our opinion, it is of human benefit to conduct epidemiological studies that will enable the estimation of the risk factors of exposure to EDCs and the probability of endocrine disorders. Increasing consumerism and the industrial boom has led to severe pollution of the environment with a corresponding negative impact on human health; thus, there is great necessity for the biomonitoring of EDCs in Poland. PMID:26136137

  10. 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.

  11. Modeling and Simulation of Abrasive Flow in Chemical Mechanical Polishing Using Discrete Element Method%化学机械抛光中磨粒运动特性离散元仿真研究

    Institute of Scientific and Technical Information of China (English)

    谭援强; 张浩; 李明军

    2011-01-01

    According to coupling computational fluid dynamics and computational granular media mechanics method, the motion of abrasive flow in CMP with composite particles was simulated using discrete element method. With PFC3D software, a two-phase flow model that predicted the kinematics and trajectory of the abrasive particles was built herein,two verification simulations were conducted to demonstrate the capability of the current method to solve nano-size two-phase flow problems. Finally, the CMP geometry simulations were conducted, some phenomenon observed in the experiments were explained.%基于耦合计算流体力学和计算散体力学的方法,利用PFC3D软件模拟了复合磨粒抛光液化学机械抛光(CMP)中抛光液固液两相流的流动行为.通过2个数值实验并将其与他人实验数据进行对比,验证了利用PFC3D软件模拟纳米两相流问题的可行性.对CMP过程进行了数值模拟,解释了一些实验中观测到的现象.

  12. Evaluation of subsurface damage in GaN substrate induced by mechanical polishing with diamond abrasives

    Energy Technology Data Exchange (ETDEWEB)

    Aida, Hideo, E-mail: h-aida@namiki.net [NJC Institute of Technology, Namiki Precision Jewel Co., Ltd., 3-8-22 Shinden, Adachi, Tokyo 123-8511 (Japan); KASTEC, Kyushu University, Kasuga-shi, Fukuoka 816-8580 (Japan); Takeda, Hidetoshi; Kim, Seong-Woo; Aota, Natsuko; Koyama, Koji [NJC Institute of Technology, Namiki Precision Jewel Co., Ltd., 3-8-22 Shinden, Adachi, Tokyo 123-8511 (Japan); Yamazaki, Tsutomu; Doi, Toshiro [KASTEC, Kyushu University, Kasuga-shi, Fukuoka 816-8580 (Japan)

    2014-02-15

    The relationship between the depth of the subsurface damage (SSD) and the size of the diamond abrasive used for mechanical polishing (MP) of GaN substrates was investigated in detail. GaN is categorized as a hard, brittle material, and material removal in MP proceeds principally to the fracture of GaN crystals. Atomic force microscopy and cathodoluminescence imaging revealed that the mechanical processing generated surface scratches and SSD. The SSD depth reduced as the diamond abrasive size reduced. A comparison of the relationship between the SSD depth and the diamond abrasive size used in the MP of GaN with the same relationship for typical brittle materials such as glass substrates suggests that the MP of GaN substrates proceeds via the same mechanism as glass.

  13. Surface studies of niobium chemically polished under conditions for superconducting radiofrequency cavity production

    Energy Technology Data Exchange (ETDEWEB)

    Hui Tian; Michael Kelley; Charles Reece

    2005-11-14

    The performance of niobium superconducting radiofrequency accelerator cavities is strongly impacted by the topmost several nanometers of the active (interior) surface, especially by the final surface conditioning treatments. We examined the effect of the most commonly employed treatment, buffered chemical polishing (BCP), on polycrystalline niobium sheet over a range of realistic solution flow rates using electron back scatter diffraction (EBSD), stylus profilometry, atomic force microscopy, laboratory XPS and synchrotron (variable photon energy) XPS, seeking to collect statistically significant data sets. We found that the predominant general surface orientation is (100), but others are also present and at the atomic-level details of surface plane orientation are more complex. The post-etch surface exhibits micron-scale roughness, whose extent does not change with treatment conditions. The outermost surface consists of a few-nm thick layer of niobium pentoxide, whose thickness increases with solution flow rate to a maximum of 1.3 - 1.4 times that resulting from static solution. The standard deviation of the roughness measurements is ?? 30% and that of the surface composition is ?? 5%.

  14. Surface studies of niobium chemically polished under conditions for superconducting radio frequency (SRF) cavity production

    Energy Technology Data Exchange (ETDEWEB)

    Tian Hui [Thomas Jefferson National Accelerator Facility and College of William and Mary (United States); Reece, Charles E. [Thomas Jefferson National Accelerator Facility and College of William and Mary (United States); Kelley, Michael J. [Thomas Jefferson National Accelerator Facility and College of William and Mary (United States)]. E-mail: mkelley@jlab.org; Wang Shancai [Department of Physics, Boston University (United States); Plucinski, Lukasz [Department of Physics, Boston University (United States); Smith, Kevin E. [Department of Physics, Boston University (United States); Nowell, Matthew M. [EDAX TSL (United States)

    2006-11-30

    The performance of niobium superconducting radiofrequency (SRF) accelerator cavities is strongly impacted by the topmost several nanometers of the active (interior) surface, especially as influenced by the final surface conditioning treatments. We examined the effect of the most commonly employed treatment, buffered chemical polishing (BCP), on polycrystalline niobium sheet over a range of realistic solution flow rates using electron back scatter diffraction (EBSD), stylus profilometry, atomic force microscopy, laboratory XPS and synchrotron (variable photon energy) XPS, seeking to collect statistically significant datasets. We found that the predominant general surface orientation is (1 0 0), but others are also present and at the atomic-level details of surface plane orientation are more complex. The post-etch surface exhibits micron-scale roughness, whose extent does not change with treatment conditions. The outermost surface consists of a few-nm thick layer of niobium pentoxide, whose thickness increases with solution flow rate to a maximum of 1.3-1.4 times that resulting from static solution. The standard deviation of the roughness measurements is {+-}30% and that of the surface composition is {+-}5%.

  15. Review on Application of Rare Earth Polishing Powders in Glass Polishing

    Institute of Scientific and Technical Information of China (English)

    Li Xueshun; Yang Guosheng

    2004-01-01

    The paper reviewed different explanations to the mechanism of glass polishing, the practices of glass polishing and the preparation of polishing powders, addressed the growth mechanism of CeO2 crystals, summarized the roles of rare earth elements in glass polishing and the factors that may influence the polishing effects, and specified the existing problems in glass polishing.

  16. Fe-Nx/C assisted chemical–mechanical polishing for improving the removal rate of sapphire

    International Nuclear Information System (INIS)

    Highlights: • A novel non-noble metal catalyst (Fe-Nx/C) was prepared. • Fe-Nx/C shows remarkable catalytic activity for improving the removal rate of sapphire in alkaline solution. • The optimum CMP removal by Fe-Nx/C yielded a superior surface finish of 0.078 nm the average roughness. • Fe2O3, Fe3O4, 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-Nx/C) is used to improve the removal mass of sapphire as well as obtain atomically smooth sapphire wafer surfaces. The results indicate that Fe-Nx/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-Nx/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 (SiO2) without Fe-Nx/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-Nx/C) with a hardness between boehmite and sapphire polish the c-plane of sapphire with good surface finish and efficient removal. Fe2O3, Fe3O4, 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-Nx/C also yields a superior surface finish of 0.078 nm the average roughness (Ra)

  17. Thermal outgassing properties of mechanically polished and of sand- and bead-blasted Inconel 600 surfaces up to 5000C

    International Nuclear Information System (INIS)

    In the present work, two different types of Inconel 600 samples have been investigated. The first one was mechanically polished and chemically cleaned in several steps and had a total hemispherical emissivity at 750C of epsilon1 = 0.146 and a surface roughness of CLA1 = 0.08 μm, while the second sample was sand- and bead-blasted with epsilon2 = 0.382 and CLA2 = 1.2 μm. The experimental studies were composed of the determination of desorption spectra from 200C up to 5500C at different heating rates, the investigation of the decrease of thermal outgassing rates during a longer heating interval at about 5000C and the measurement of equilibrium outgassing rates at higher temperatures of samples which have been heated several days at about 5000C. The total outgassing rates and the partial outgassing rates of the main components H2, H2O, CO and CO2 have been determined in these studies. Activation energies of desorption, rate constants and equilibrium surface coverages have been calculated from the experimental data using the theory of Redhead. (author)

  18. Summaries of the 40. Scientific Assembly of Polish Chemical Society and Association of Engineers and Technicians of Chemical Industry; Streszczenia 40. Zjazdu Naukowego Polskiego Towarzystwa Chemicznego i Stowarzyszenia Inzynierow i Technikow Przemyslu Chemicznego

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1997-12-31

    Annual 40. Scientific Assembly of Polish Chemical Society and Association of Engineers and Technicians of Chemical Industry has been held in Gdansk on 22-26 September 1997. The most valuable scientific results obtained in Polish Laboratories have been presented in 22 main sections and 7 symposia directed especially at following subjects: analytical chemistry, biochemistry, solid state chemistry and material science, physical chemistry, heteroorganic and coordination chemistry, medical and pharmaceutical chemistry, metalorganic chemistry, inorganic and organic chemistry, polymers chemistry, chemistry and environment protection, theoretical chemistry, chemical didactics, photochemistry, radiation chemistry and chemical kinetics, chemical engineering, catalysis, crystallochemistry, chemical technology, electrochemistry, and instrumental methods.

  19. Mechanisms of multiple chemical sensitivity.

    Science.gov (United States)

    Winder, Chris

    2002-03-10

    Sensitivity to chemicals is a toxicological concept, contained in the dose-response relationship. Sensitivity also includes the concept of hypersensitivity, although controversy surrounds the nature of effects from very low exposures. The term multiple chemical sensitivity has been used to describe individuals with a debilitating, multi-organ sensitivity following chemical exposures. Many aspects of this condition extend the nature of sensitivity to low levels of exposure to chemicals, and is a designation with medical, immunological, neuropsychological and toxicological perspectives. The basis of MCS is still to be identified, although a large number of hypersensitivity, immunological, psychological, neurological and toxicological mechanisms have been suggested, including: allergy; autosuggestion; cacosomia; conditioned response; immunological; impairment of biochemical pathways involved in energy production; impairment of neurochemical pathways; illness belief system; limbic kindling; olfactory threshold sensitivity; panic disorder; psychosomatic condition; malingering; neurogenic inflammation; overload of biotransformation pathways (also linked with free radical production); psychological or psychiatric illness; airway reactivity; sensitisation of the neurological system; time dependent sensitisation, toxicant induced loss of tolerance. Most of these theories tend to break down into concepts involving: (1) disruption in immunological/allergy processes; (2) alteration in nervous system function; (3) changes in biochemical or biotransformation capacity; (4) changes in psychological/neurobehavioural function. Research into the possible mechanisms of MCS is far from complete. However, a number of promising avenues of investigation indicate that the possibility of alteration of the sensitivity of nervous system cells (neurogenic inflammation, limbic kindling, cacosomia, neurogenic switching) are a possible mechanism for MCS.

  20. Materials of yearly scientific assembly of Polish Chemical Society, Lublin 1995; Materialy ze zjazdu naukowego Polskiego Towarzystwa Chemicznego, Lublin 1995

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1995-12-31

    Scientific conference accompanied the yearly assembly of Polish Chemical Society has bee held in 1995 in Lublin. The general review on scientific progress of the most important field of chemistry in Poland have been presented. The conference has been divided into 16 plenary sessions and 3 microsymposia. The sessions topics as follows: S-1 - physical chemistry; S-2 - physicochemistry of the surface; S-3 - catalysis; S-4 - chemical technology; S-5 - inorganic chemistry; S-6 - coordination chemistry; S-7 -crystallochemistry; S-8 - electrochemistry; S-9 - organic chemistry; S-10 -chemistry of polymers; S-11 - chemistry in medicine; S-12 - chemistry and technology of solid state materials; S-13 - young scientists forum; S-14 -didactics in chemistry; S-15 - theoretical chemistry; S-16 - environmental protection. Also the 3 microsymposia have been organized. It was: M-1 -chemistry of heteroorganic compounds; M-2 chromatography; M-3 - plasma chemistry.

  1. Fate of indicator endocrine disrupting chemicals in sewage during treatment and polishing for non-potable reuse.

    Science.gov (United States)

    Holmes, Mike; Kumar, Anu; Shareef, Ali; Doan, Hai; Stuetz, Richard; Kookana, Rai

    2010-01-01

    The removal and fate of several indicator endocrine disrupting chemicals (EDCs) at two large municipal wastewater treatment plants (WWTPs) in Adelaide South Australia was investigated. Non-estrogens included the non-ionic surfactant breakdown compounds nonyl phenol mono- and di-ethoxylates, 4-t-octylphenol and 4-nonyl phenol; and, the plasticizer bisphenol A. Estrogens included 17β-estradiol; estrone; and, 17α-ethynylestradiol. Effluent from Bolivar WWTP is polished using stabilisation lagoons followed by coagulation, dissolved air flotation/filtration and chlorination for non-potable reuse. Biosolids from both plants is applied to agricultural land as a soil conditioner. Non-estrogen indicator EDCs were detected at the highest concentration in sewage, effluent and sludge but estrogen indicator EDCs contributed the greatest potential for estrogenicity. The fate of indicator EDCs at various treatment stages is complex and includes biochemical modification/transformation and/or partitioning to either solid or liquid phases. Activated sludge treatment was an important removal barrier achieving moderate-high removal of predicted and YES (a yeast screen assay) measured estrogen equivalent values (EEq). Combined polishing treatment achieved high removal of candidate EDCs (97%). Mass balance indicates that the largest source of estrogenicity discharged from both WWTPs investigated is digested sludge which accounts for 18 and 22% respectively of the combined predicted and YES measured EEq measured in sewage at the two WWTPs. PMID:20861558

  2. Structural features of metallic phase formed under the action of mechanical polishing of SmS polycrystalline specimens

    International Nuclear Information System (INIS)

    By means of X-ray diffractometry one investigated into structural features of a metallic phase film resulting from the balanced polishing of Sm1+xS semiconducting polycrystalline specimens within homogeneity range. One investigated into structural changes occurring in that case in semiconducting phase. On the basis of analysis of thickness dependence of metallic layers formed at the specimen surface on x one explains mechanism of influence of amount of samarium excessive ions on the transition parameters. The evaluations based on measurement results of dimensions of X-ray radiation coherent scattering ranges (CSR) in various composition specimens enabled to explain the reason of stabilization of SmS metallic modification upon termination of polishing. Occurrence and stabilization of metallic phase are associated with reduction and retaining of CSR dimensions

  3. Planarization mechanism of alkaline copper CMP slurry based on chemical mechanical kinetics

    Institute of Scientific and Technical Information of China (English)

    Wang Shengli; Yin Kangda; Li Xiang; Yue Hongwei; Liu Yunling

    2013-01-01

    The planarization mechanism of alkaline copper slurry is studied in the chemical mechanical polishing (CMP) process from the perspective of chemical mechanical kinetics.Different from the international dominant acidic copper slurry,the copper slurry used in this research adopted the way of alkaline technology based on complexation.According to the passivation property of copper in alkaline conditions,the protection of copper film at the concave position on a copper pattern wafer surface can be achieved without the corrosion inhibitors such as benzotriazole (BTA),by which the problems caused by BTA can be avoided.Through the experiments and theories research,the chemical mechanical kinetics theory of copper removal in alkaline CMP conditions was proposed.Based on the chemical mechanical kinetics theory,the planarization mechanism of alkaline copper slurry was established.In alkaline CMP conditions,the complexation reaction between chelating agent and copper ions needs to break through the reaction barrier.The kinetic energy at the concave position should be lower than the complexation reaction barrier,which is the key to achieve planarization.

  4. Laser polishing of niobium for superconducting radio-frequency accelerator applications

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Liang [William and Mary College; Klopf, John M. [William and Mary College; Reece, Charles E. [JLAB; Kelley, Michael J. [JLAB

    2014-08-01

    Interior surfaces of niobium cavities used in superconducting radio frequency accelerators are now obtained by buffered chemical polish and/or electropolish. Laser polishing is a potential alternative, having advantages of speed, freedom from noxious chemistry and availability of in-process inspection. We studied the influence of the laser power density and laser beam raster rate on the surface topography. These two factors need to be combined carefully to smooth the surface without damage. Computational modeling was used to estimate the surface temperature and gain insight into the mechanism of laser polishing. Power spectral density analysis of surface topography measurements shows that laser polishing can produce smooth topography similar to that obtained by electropolish. This is a necessary first step toward introducing laser polishing as an alternative to the currently practiced chemical polishing.

  5. Substrate preparation by contactless mechanochemical polish

    Science.gov (United States)

    Rotter, S.; Lachish, U.; El-Hanany, U.

    1985-10-01

    A simple, yet effective, polishing technique for substrate preparation is presented. It is contactless chemical polish which does not introduce any defects into the substrate during the process. The method can be readily adopted in all cases where chemical polishing is practical for substrate preparation. Results similar to those obtained by the more sophisticated hydroplaning method can be achieved.

  6. Buffer Chemical Polishing and RF Testing of the 56 MHz SRF Cavity

    Energy Technology Data Exchange (ETDEWEB)

    Burrill,A.

    2009-01-01

    The 56 MHz cavity presents a unique challenge in preparing it for RF testing prior to construction of the cryomodule. This challenge arises due to the physical dimensions and subsequent weight of the cavity, and is further complicated by the coaxial geometry, and the need to properly chemically etch and high pressure rinse the entire inner surface prior to RF testing. To the best of my knowledge, this is the largest all niobium SRF cavity to be chemically etched and subsequently tested in a vertical dewar at 4K, and these processes will be the topic of this technical note.

  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. PMID:27194943

  8. 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

  9. The Family Meeting as a Mechanism of Family Governance: Review of the Experiences of Polish Family Companies

    Directory of Open Access Journals (Sweden)

    Izabela Koładkiewicz

    2014-09-01

    Full Text Available Purpose: The objective of the research was an assessment of the experiences of Polish owners of family companies in organizing family meetings as mechanisms of family governance as well as evaluating the usefulness of solutions developed in this sphere for both family and company. Methodology: The character of the conducted research was qualitative. The main technique used to gather data involved interviews. A total of thirty nine respondents from twenty companies were questioned. Nineteen were representatives of the older generation while twenty represented the younger second generation of owners of family businesses. Findings: Research results indicated the rather extensive use by the examined owner families of family meetings to discuss company matters. Depending on their needs, they developed various models ranging from the ad hoc bringing up of company matters to the transformation of such meetings into formal, family meetings of the management board organized in company offi ces. Regardless of organizational form, family meetings were an important forum for the exchange of information and views on the functioning of the company among family members. The experiences of the examined families of owners in building family governance systems, understood as a complex of structures and mechanisms making possible the maintenance of a balance between tensions stemming from economic and emotional ties among family members, both involved in the company and outside it, remain small. Research limitations: The qualitative character of the research, including the size of the examined sample (twenty family companies represented by thirty nine representatives, means that the generalizations made for the purposes of this study refer only to the experiences and opinions of the interviewed respondents. Originality: The research performed is the fi rst of its kind devoted to family meetings as a component of the system of family governance created in the

  10. Materials of jubilee scientific assembly of the Polish Chemical Society, Warsaw`94. Homo chemicus; Materialy z jubileuszowego zjazdu Polskiego Towarzystwa Chemicznego, Warszawa`94. Homo chemicus

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1994-12-31

    The Jubilee Scientific Assembly of the Polish Chemical Society has been held in 1994 in Warsaw. The general view on scientific progress in chemistry in Poland has been presented during plenary session. The conference has been divided into 15 sessions and 3 microsymposia covering the most important research fields in chemistry. Sessions topics were: analytical chemistry, chemistry of solid state materials, physical chemistry, coordination chemistry, medical chemistry, chemistry of metalorganic compounds, inorganic chemistry, organic chemistry, chemistry of polymers, young scientists forum, didactics and history of chemistry, catalysis, crystallochemistry, chemical technology, environment protection. Microsymposia`s topics were as follows: chemistry of saccharides, electrochemistry, membranes and membrane processes.

  11. Mechanism analysis on finishing of reaction-sintered silicon carbide by combination of water vapor plasma oxidation and ceria slurry polishing

    Science.gov (United States)

    Shen, Xinmin; Tu, Qunzhang; Deng, Hui; Jiang, Guoliang; Yamamura, Kazuya

    2015-05-01

    Reaction-sintered silicon carbide (RS-SiC), which is considered as a promising mirror material for space telescope systems, requires a high surface property. An ultrasmooth surface with a Ra surface roughness of 0.480 nm was obtained after water vapor plasma oxidation for 90 min followed by ceria slurry polishing for 40 min. The oxidation process of RS-SiC by water vapor plasma was analyzed based on the Deal-Grove model, and the theoretical calculation results are consistent with the measured data obtained by scanning white light interferometer (SWLI), scanning electron microscopy/energy-dispersive x-ray, and atomic force microscope. The polishing process of oxidized RS-SiC by ceria slurry was investigated according to the Preston equation, which would theoretically forecast the evolutions of RS-SiC surfaces along with the increasing of polishing time, and it was experimentally verified by comparing the surface roughnesses obtained by SWLI and the surface morphologies obtained by SEM. The mechanism analysis on the finishing of RS-SiC would be effective for the optimization of water vapor plasma oxidation parameters and ceria slurry polishing parameters, which will promote the application of RS-SiC substrates by improving the surface property obtained by the oxidation-assisted polishing method.

  12. Materials of yearly scientific assembly of Polish Chemical Society, Poznan 23-26 September 1996; Materialy ze zjazdu naukowego Polskiego Towarzystwa Chemicznego, Poznan 23-26 wrzesnia 1996

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1996-12-31

    The Scientific Assembly of Polish Chemical Society has been held in 1996 in Poznan. The general view on scientific progress of chemistry in Poland has been presented. The conference has been divided into 18 sessions covering the most important research fields in chemistry. The sessions topics were as follows: S-1 physical chemistry; S-2 photochemistry, radiation chemistry and chemical kinetics; S-3 catalysis; S-4 inorganic chemistry and coordination chemistry; S-5 organic chemistry; S-6 chemistry of hetero organic compounds; S-7 medical chemistry; S-8 crystallochemistry; S-9 environment protection; S-10 didactics in chemistry; S-11 analytical chemistry; S-12 chemical technology; S-13 chemical engineering; S-14 chemistry of polymers; S-15 young chemists forum; S-16 professor forum; S-17 membranes and membrane processes; S-18 supermolecular chemistry.

  13. Materials of the yearly scientific assembly of the Polish Chemical Society - Torun`93: chemistry of new materials; Materialy z dorocznego zjazdu naukowego - Torun`93: chemia nowych materialow

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1993-12-31

    Scientific conference accompanied the assembly of Polish Chemical Society has been held in 1993 in Torun. The conference has been divided into 12 sections and 4 symposia covering the most important research fields in chemistry. The general view on scientific progress has been presented during the plenary session. Then proceedings have performed in specialist sessions on: contemporary methods in organic chemistry chemistry, chemistry and physico-chemistry of polymers, coordination chemistry state-of-the-art prospects, absorption and absorbents, new chemical technologies of organic compounds, new chemical technologies of inorganic compounds, environment protection, new methods in analytical chemistry, photochemistry and chemical kinetics, crystallochemistry, history of chemistry and didactics, new substances in health protection, membranes and membrane techniques, electroactive organic compounds, zeolites - material properties.

  14. Defectivity control of aluminum chemical mechanical planarization in replacement metal gate process of MOSFET

    Science.gov (United States)

    Jin, Zhang; Yuling, Liu; Chenqi, Yan; Yangang, He; Baohong, Gao

    2016-04-01

    The replacement metal gate (RMG) defectivity performance control is very challenging in high-k metal gate (HKMG) chemical mechanical polishing (CMP). In this study, three major defect types, including fall-on particles, micro-scratch and corrosion have been investigated. The research studied the effects of polishing pad, pressure, rotating speed, flow rate and post-CMP cleaning on the three kinds of defect, which finally eliminated the defects and achieved good surface morphology. This study will provide an important reference value for the future research of aluminum metal gate CMP. Project supported by the Major National Science and Technology Special Projects (No. 2009ZX02308), the Natural Science Foundation for the Youth of Hebei Province (Nos. F2012202094, F2015202267), and the Outstanding Youth Science and Technology Innovation Fund of Hebei University of Technology (No. 2013010).

  15. A flexible nanobrush pad for the chemical mechanical planarization of Cu/ultra-low-к materials

    Science.gov (United States)

    Han, Guiquan; Liu, Yuhong; Lu, Xinchun; Luo, Jianbin

    2012-10-01

    A new idea of polishing pad called flexible nanobrush pad (FNP) has been proposed for the low down pressure chemical mechanical planarization (CMP) process of Cu/ultra-low-к materials. The FNP was designed with a surface layer of flexible brush-like nanofibers which can `actively' carry nanoscale abrasives in slurry independent of the down pressure. Better planarization performances including high material removal rate, good planarization, good polishing uniformity, and low defectivity are expected in the CMP process under the low down pressure with such kind of pad. The FNP can be made by template-assisted replication or template-based synthesis methods, which will be driven by the development of the preparation technologies for ordered nanostructure arrays. The present work would potentially provide a new solution for the Cu/ultra-low-к CMP process.

  16. A Finite Element Model for Wafer Materiall Removal Rate and Non-uniformity in Chemical Mechanical Polishing Process%机械化学抛光中晶圆材料切削率和非均匀性有限元模型

    Institute of Scientific and Technical Information of China (English)

    郭跃彬

    2001-01-01

    提出了一个机械化学抛光中晶圆材料非均匀性的有限元模型.通过分析压力、摩擦力、抛光垫和承载膜的可压缩性对晶圆的应力分布的影响,研究了抛光过程中晶圆厚度的不均匀性.结果证明非均匀剪应力是晶圆厚度变化的一个主要原因.这个模型也建立了声发射信号的变化和晶圆厚度不均匀性的关系.通过对晶圆材料切削率的声发射信号监测,证明了实验结果和模型预测值的一致性.%A 3D finite element model is presented for wafer non-uniformity in chemicalmechanical polishing(CMP)process. Film thickness non-uniformity of the wafer during CMPprocess was investigated by examining the influence of applied pressure, friction force,pad andcarrier film compressibility on stress distribution across the wafer diameter. It shows that non-uniform shear stress distribution on wafer plays an important role on the non-uniformity. Themodel relates the variation of acoustic emission (AE)signal from non-uniform stress distribu-tion on the wafer to its non-uniformity. The agreement between model prediction and experi-mental results is demonstrated by AE monitoring of material removal rate in CMP process.

  17. 铜及铜合金不同化学抛光工艺研究%Study on different chemical polishing processes for copper and copper alloys

    Institute of Scientific and Technical Information of China (English)

    农兰平; 李金莲; 巩育军

    2011-01-01

    对铜及铜合金化学抛光工艺进行了研究,考察了低浓度硝酸体系和双氧水体系对铜及其合金的抛光亮度、腐蚀失重以及对环境污染程度的影响.结果表明,低浓度硝酸体系抛光亮度高,适用范围广,对环境的污染较传统三酸体系少,虽然对铜及铜合金有一定的腐蚀,但返工对工件的尺寸影响不大,适用于冰箱、空调器等的蒸发管的抛光.双氧水抛光体系对铜及其合金腐蚀轻微,对环境的污染更少,但成本相对较高,适于对加工尺寸要求严格的铜及铜合金电子元件的化学抛光.%The chemical polishing process for copper and its alloy was studied. The influence of a low concentration nitric acid system and a hydrogen peroxide system on the polishing brightness, corrosion weight loss and environmental pollution level was discussed. The results showed that the low concentration nitric acid system has a high polishing brightness and a wide application areas, results in a great improvement in reducing environmental pollution as compared with the traditional three-acid system, and is suitable for polishing the evaporator pipes in refrigerator or air conditioner. Although it causes a slight corrosion of copper and its alloys, there is only a little effect on the size of workpiece during reprocessing. The hydrogen peroxide system features slight corrosion of copper and its alloys and less environmental pollution, but higher cost. It can be applied to chemical polishing of electronic components made of copper and copper alloys with strict request on the size and shape.

  18. Characterization of implant materials in fetal bovine serum and sodium sulfate by electrochemical impedance spectroscopy. I. Mechanically polished samples.

    Science.gov (United States)

    Contu, F; Elsener, B; Böhni, H

    2002-12-01

    Electrochemical impedance spectroscopy is used to monitor the long-term stability (up to 150 days) of mechanically polished commercial pure titanium, Ti6Al4V, Ti6Al7Nb, and CoCrMo alloys in 0.1M sodium sulfate and fetal bovine serum. A capacitive spectrum in the frequency range from 10(-3) to 10(5) Hz is always found and the impedance spectra can be fitted by a simple parallel RC circuit with a constant phase element. The open circuit potential observed in serum is always more cathodic and the polarization resistance (R(p)) is higher than that recorded in sodium sulfate solutions. The observed variation of the equivalent capacitance in serum bovine suggests that an adsorption layer of organic molecules develops on the electrode surface and it is responsible for both the decrease in open circuit potential and the higher R(p), because it hinders the oxygen evolution reaction and the charge transfer responsible for the passive film dissolution (or growth). Among the alloys studied, Ti6Al4V displayed the highest steady-state values of R(p) both in serum and in sodium sulfate.

  19. Mechanical and chemical properties of sewage pipes

    OpenAIRE

    Ł. Wierzbicki; M. Szymiczek

    2012-01-01

    Purpose: The purpose of this paper was to evaluate the compatibility of the physico-chemical properties of sewage pipes with the requirements of PN – EN ISO 1401-01: Plastics piping systems for non-pressure underground drainage and sewerage. This article is based on a research carried out for the water supply company. The article presents the results of mechanical and chemical testing of four pipes of unplasticized polyvinyl chloride and one pipe of polypropylene. All the test pipes were app...

  20. Dissolution, corrosion and environmental issues in chemical mechanical planarization of copper

    Science.gov (United States)

    Tamilmani, Subramanian

    Chemical mechanical polishing (CMP) of dielectric and metal films has become a key process in manufacturing devices with ultra large scale integration (ULSI). In a CMP process, planarization is achieved by polishing a wafer with uneven topography using colloidal slurry consisting of sub-micron sized abrasive particles, oxidant and various additives. Hydrogen peroxide and hydroxylamine are commonly used oxidants in copper CMP process. To achieve planarization, the low lying areas have to be protected while the higher areas are polished away. This requires low static dissolution rate of copper in low areas. Another major issue in copper CMP is galvanic corrosion during barrier polishing step where both copper and the barrier metal are exposed to the slurry. The main goal of the research reported in this dissertation is to understand the dissolution and corrosion issues during the removal of copper in hydroxylamine based chemistries. Electrochemical and physical methods such as profilometry were used to obtain copper removal rates. Among the variety of organic compound tested, benzotriazole and salicylhydroxamic acid were identified as potential corrosion inhibitors for copper. The passive film formed on the copper surface by the addition of benzotriazole and salicylhydroxamic acid was characterized by X-ray photoelectron spectroscopy and atomic force microscopy. The passivation and repassivation kinetics were investigated in detail and a passivation mechanism for copper in hydroxylamine in the presence of benzotriazole and salicylhydroxamic acid chemistries is proposed. Copper removal experiments were performed on a specially designed electrochemical abrasion cell (EC-AC) in the presence and absence of inhibitors. The effect of anodic potentials on the dissolution of copper in various chemistries was studied to identify suitable conditions for electro-chemical mechanical planarization process. The extent of galvanic corrosion between copper and tantalum was estimated

  1. Implications of Polishing Techniques in Quantitative X-Ray Microanalysis

    Science.gov (United States)

    Rémond, Guy; Nockolds, Clive; Phillips, Matthew; Roques-Carmes, Claude

    2002-01-01

    Specimen preparation using abrasives results in surface and subsurface mechanical (stresses, strains), geometrical (roughness), chemical (contaminants, reaction products) and physical modifications (structure, texture, lattice defects). The mechanisms involved in polishing with abrasives are presented to illustrate the effects of surface topography, surface and subsurface composition and induced lattice defects on the accuracy of quantitative x-ray microanalysis of mineral materials with the electron probe microanalyzer (EPMA). PMID:27446758

  2. Synergetic effect of organic cores and inorganic shells for core/shell structured composite abrasives for chemical mechanical planarization

    International Nuclear Information System (INIS)

    Highlights: • The damage-free polishing mechanism of core/shell composite abrasive was explored. • The organic core is help to decrease surface roughness and mechanical damages. • The inorganic shell is in favor of improving material removal rate. • The enhanced CMP behavior is due to the synergistic effect between core and shell. - Abstract: Core/shell structured organic/inorganic composite microspheres has an important potential application in efficient and damage-free chemical mechanical planarization/polishing (CMP) as a kind of novel abrasive due to its uniform non-rigid mechanical property. However, the synergistic effect of material removal between organic cores and inorganic shells of composite abrasives is ambiguous. In this work, oxide-CMP performances of various slurries, containing polystyrene (PS) spheres, solid abrasives (SiO2 or CeO2), mixed abrasives ((PS + SiO2) or (PS + CeO2)), core/shell composites (PS/SiO2 or PS/CeO2), were investigated by atomic force microscopy. Experiment results indicated that the surfaces polished by composite abrasives exhibited lower surface roughness, fewer scratches as well as lower topographical variations than those by other type of abrasives. The core/shell structure of composite abrasives plays an important role in improving CMP behavior. Moreover, the organic cores are mainly beneficial to decrease surface roughness and mechanical damages, and the inorganic shells are in favor of improving material removal rate

  3. Synergetic effect of organic cores and inorganic shells for core/shell structured composite abrasives for chemical mechanical planarization

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Yang, E-mail: cy.jpu@126.com [School of Materials Science and Engineering, Changzhou University, Changzhou, Jiangsu 213164 (China); Li, Zhina [School of Materials Science and Engineering, Changzhou University, Changzhou, Jiangsu 213164 (China); Miao, Naiming [School of Mechanical Engineering, Changzhou University, Changzhou, Jiangsu 213016 (China)

    2014-09-30

    Highlights: • The damage-free polishing mechanism of core/shell composite abrasive was explored. • The organic core is help to decrease surface roughness and mechanical damages. • The inorganic shell is in favor of improving material removal rate. • The enhanced CMP behavior is due to the synergistic effect between core and shell. - Abstract: Core/shell structured organic/inorganic composite microspheres has an important potential application in efficient and damage-free chemical mechanical planarization/polishing (CMP) as a kind of novel abrasive due to its uniform non-rigid mechanical property. However, the synergistic effect of material removal between organic cores and inorganic shells of composite abrasives is ambiguous. In this work, oxide-CMP performances of various slurries, containing polystyrene (PS) spheres, solid abrasives (SiO{sub 2} or CeO{sub 2}), mixed abrasives ((PS + SiO{sub 2}) or (PS + CeO{sub 2})), core/shell composites (PS/SiO{sub 2} or PS/CeO{sub 2}), were investigated by atomic force microscopy. Experiment results indicated that the surfaces polished by composite abrasives exhibited lower surface roughness, fewer scratches as well as lower topographical variations than those by other type of abrasives. The core/shell structure of composite abrasives plays an important role in improving CMP behavior. Moreover, the organic cores are mainly beneficial to decrease surface roughness and mechanical damages, and the inorganic shells are in favor of improving material removal rate.

  4. Investigation of the chemical and electrochemical phenomena in the chemical mechanical planarization of copper

    Science.gov (United States)

    Wang, Ling

    Chemical mechanical planarization (CMP), a polishing process in which uneven surfaces of a copper film deposited on a wafer are planarized using chemically active slurry containing sub-micron abrasive particles, is key for the metallization of multilevel copper interconnection wires on integrated circuits by damascene processes. The present dissertation study investigates the electrochemical and chemical behavior of copper in aqueous solutions containing chemical reagents representative of those in CMP slurries, and the effects of these chemical constituents, with the aim of improving our understanding of the chemical processes responsible, at least in part, for planarization and material removal in copper CMP, and providing mechanistic and quantitative information for developing comprehensive predictive CMP removal models that incorporate chemical, electrochemical and mechanical factors. In the first part of the dissertation, the passivation behavior of copper in solutions containing hydrogen peroxide and glycine was examined, using various characterization techniques including electrochemical polarization curve measurements, copper coupon exposure tests, and electrochemical quartz crystal microbalance measurements. Polarization curves were measured with a rotating disk copper electrode in glycine solution, in the presence and absence of hydrogen peroxide, to understand the role of hydrogen peroxide in the oxidative dissolution and passivation of copper. Weight loss and copper solubilization measurements were conducted by exposing copper coupons to glycine solutions containing hydrogen peroxide, with various concentrations, at different solution pHs, to characterize the development and degree of the peroxide-induced passivation of copper and to obtain the kinetics of copper dissolution, in order to gain insight into the passivation mechanisms of copper in the peroxide-glycine-based solutions. The Quartz Crystal Microbalance (QCM) measurements were conducted with

  5. 铝合金轮毂曲面CNC机械抛光轮廓控制方法研究%Research on Contour Control Method of CNC Mechanical Polishing Machine for Aluminum Alloy Wheel Hub Surface

    Institute of Scientific and Technical Information of China (English)

    吴昌林; 丁和艳; 陈义

    2009-01-01

    研发了新型圆柱坐标式五坐标联动轮毂曲面CNC机械抛光专用机床,该机床能实现三个气动或电动抛光轮同步抛光轮毂表面.机床采用双层立式的主体机械结构.抛光轮运动轨迹数据源于轮毂CAD/CAM模型.机床控制系统采用抛光轮位姿和抛光力混合控制策略.实验结果表明,轮毂CNC机械抛光后表面粗糙度与手工抛光的表面粗糙度相当,但抛光效率高10倍以上.%An advanced and novel computer numerical control mechanical polishing machine was developed. The machine is of double-layer and vertical struction, and the five-axis CNC system is based on cylindrical coordinate. The machine was suitable for mechanical polishing aluminum-alloy wheel hubs and can even polish one wheel hub with three polishing tools at the same time. How the machine worked was introduced, and especially how the polishing tools followed the surface was discussed,which was based on the hybrid control of position, orientation and polishing force. The CL data was from the wheel hub's CAD/CAM model. Many polishing experiments have showed that the special purpose CNC polishing machine with surface following control system has the same effect on surface roughness as with skilled workers, while the special purpose CNC polishing machine is more efficient and can replace many migrant workers in wheel hub machining.

  6. Mechanical and Chemical Signaling in Angiogenesis

    CERN Document Server

    2013-01-01

    This volume of Studies in Mechanobiology, Tissue Engineering and Biomaterials describes the most recent advances in angiogenesis research at all biological length scales: molecular, cellular and tissue, in both in vivo and in vitro settings.  Angiogenesis experts from diverse fields including engineering, cell and developmental biology, and chemistry have contributed chapters which focus on the mechanical and chemical signals which affect and promote blood vessel growth. Specific emphasis is given to novel methodologies and biomaterials that have been developed and applied to angiogenesis research. 

  7. Reaction Mechanism Generator: Automatic construction of chemical kinetic mechanisms

    Science.gov (United States)

    Gao, Connie W.; Allen, Joshua W.; Green, William H.; West, Richard H.

    2016-06-01

    Reaction Mechanism Generator (RMG) constructs kinetic models composed of elementary chemical reaction steps using a general understanding of how molecules react. Species thermochemistry is estimated through Benson group additivity and reaction rate coefficients are estimated using a database of known rate rules and reaction templates. At its core, RMG relies on two fundamental data structures: graphs and trees. Graphs are used to represent chemical structures, and trees are used to represent thermodynamic and kinetic data. Models are generated using a rate-based algorithm which excludes species from the model based on reaction fluxes. RMG can generate reaction mechanisms for species involving carbon, hydrogen, oxygen, sulfur, and nitrogen. It also has capabilities for estimating transport and solvation properties, and it automatically computes pressure-dependent rate coefficients and identifies chemically-activated reaction paths. RMG is an object-oriented program written in Python, which provides a stable, robust programming architecture for developing an extensible and modular code base with a large suite of unit tests. Computationally intensive functions are cythonized for speed improvements.

  8. Effect of pH and chemical mechanical planarization process conditions on the copper–benzotriazole complex formation

    Science.gov (United States)

    Cho, Byoung-Jun; Kim, Jin-Yong; Hamada, Satomi; Shima, Shohei; Park, Jin-Goo

    2016-06-01

    Benzotriazole (BTA) has been used to protect copper (Cu) from corrosion during Cu chemical mechanical planarization (CMP) processes. However, an undesirable Cu–BTA complex is deposited after Cu CMP processes and it should be completely removed at post-Cu CMP cleaning for next fabrication process. Therefore, it is very important to understand of Cu–BTA complex formation behavior for its applications such as Cu CMP and post-Cu CMP cleaning. The present study investigated the effect of pH and polisher conditions on the formation of Cu–BTA complex layers using electrochemical techniques (potentiodynamic polarization and electrochemical impedance spectroscopy) and the surface contact angle. The wettability was not a significant factor for the polishing interface, as no difference in the contact angles was observed for these processes. Both electrochemical techniques revealed that BTA had a unique advantage of long-term protection for Cu corrosion in an acidic condition (pH 3).

  9. Potassium sorbate as an inhibitor in copper chemical mechanical planarization slurry. Part I. Elucidating slurry chemistry

    Energy Technology Data Exchange (ETDEWEB)

    Nagar, Magi; Starosvetsky, David [Department of Materials Engineering, Technion Israel Institute of Technology, Haifa 32000 (Israel); Vaes, Jan [IMEC, Kapeldreef 75, B-3001 Leuven (Belgium); Ein-Eli, Yair, E-mail: eineli@tx.technion.ac.i [Department of Materials Engineering, Technion Israel Institute of Technology, Haifa 32000 (Israel)

    2010-04-01

    The integration of an advanced inhibitor, potassium sorbate (K[CH{sub 3}(CH){sub 4}CO{sub 2}]), in a copper CMP slurry based on hydrogen peroxide and glycine is reported. The first part of the study discusses the slurry chemistry by qualitatively describing the processes involved and proposes a mechanism for a hydrogen peroxide-glycine based slurry having sorbate anion as an inhibitor. For this purpose, the specific role of each chemical constituent in the slurry was elucidated at a fundamental level by electrochemical studies, X-ray photon spectroscopy (XPS) and contact angle measurements, all linked to the CMP performance on blanket wafers. Once the polishing mechanism was resolved the influence of the inhibitor was evaluated by CMP processing of patterned wafers.

  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. An advanced alkaline slurry for barrier chemical mechanical planarization on patterned wafers

    Institute of Scientific and Technical Information of China (English)

    Wang Chenwei; Liu Yuling; Niu Xinhuan; Tian Jianying; Gao Baohong; Zhang Xiaoqiang

    2012-01-01

    We have developed an alkaline barrier slurry (named FA/O slurry) for barrier removal and evaluated its chemical mechanical planarization (CMP) performance through comparison with a commercially developed barrier slurry.The FA/O slurry consists of colloidal silica,which is a complexing and an oxidizing agent,and does not have any inhibitors.It was found that the surface roughness of copper blanket wafers polished by the FA/O slurry was lower than the commercial barrier slurry,demonstrating that it leads to a better surface quality.In addition,the dishing and electrical tests also showed that the patterned wafers have a lower dishing value and sheet resistance as compared to the commercial barrier slurry.By comparison,the FA/O slurry demonstrates good planarization performance and can be used for barrier CMP.

  12. Learning the mechanisms of chemical disequilibria

    Science.gov (United States)

    Nicholson, Schuyler B.; Alaghemandi, Mohammad; Green, Jason R.

    2016-08-01

    When at equilibrium, large-scale systems obey thermodynamics because they have microscopic configurations that are typical. "Typical" states are a fraction of those possible with the majority of the probability. A more precise definition of typical states underlies the transmission, coding, and compression of information. However, this definition does not apply to natural systems that are transiently away from equilibrium. Here, we introduce a variational measure of typicality and apply it to atomistic simulations of a model for hydrogen oxidation. While a gaseous mixture of hydrogen and oxygen combusts, reactant molecules transform through a variety of ephemeral species en route to the product, water. Out of the exponentially growing number of possible sequences of chemical species, we find that greater than 95% of the probability concentrates in less than 1% of the possible sequences. Overall, these results extend the notion of typicality across the nonequilibrium regime and suggest that typical sequences are a route to learning mechanisms from experimental measurements. They also open up the possibility of constructing ensembles for computing the macroscopic observables of systems out of equilibrium.

  13. 45钢电解-机械复合抛光工艺优化%Optimization of the process for combined electrochemical and mechanical polishing of 45 steel

    Institute of Scientific and Technical Information of China (English)

    时君丽; 周茂军; 曲洪伟

    2013-01-01

    采用电解-机械复合抛光工艺处理某压缩机45钢曲轴,以改善其表面粗糙度。通过单因素试验和正交试验对电解-机械复合抛光工艺进行优化,得到的最佳工艺条件如下:对于脉冲电解抛光,输出频率1000 Hz,方波占空比50%,电解液NaNO3的质量分数20%,电流密度50 A/cm2,工作电压10 V;对于机械抛光,砂轮转速160 r/min,磨削压力2 kg/cm2,砂带粒度号1500#。在最佳电解-机械复合抛光工艺下,45钢的粗糙度 Ra均低于0.3μm,比抛光前降低了70%以上,满足粗糙度应低于0.5μm的加工要求。%The crankshaft of a compressor was treated by combined electrochemical and mechanical polishing for improving its roughness. The optimized process conditions by single factor experiment and orthogonal test are as follows:for pulse electropolishing, output frequency 1 000 Hz, duty cycle of square wave 50%, mass fraction of HNO3 in electrolyte 20%, current density 50 A/cm2, and working voltage 10 V;and for mechanical polishing, rotation rate of abrasive wheel 160 r/min, grinding force 2 kg/cm2, and granularity of abrasive belt 1500#. Under the optimal process conditions, the roughness (Ra) of polished 45 steel is not higher than 0.3μm, which is 70%lower than that of the unpolished one, meeting the roughness requirement of less than 0.5μm.

  14. Chemical Mechanism Solvers in Air Quality Models

    OpenAIRE

    Linford, John C.; Adrian Sandu; Rolf Sander; Hong Zhang

    2011-01-01

    The solution of chemical kinetics is one of the most computationally intensive tasks in atmospheric chemical transport simulations. Due to the stiff nature of the system, implicit time stepping algorithms which repeatedly solve linear systems of equations are necessary. This paper reviews the issues and challenges associated with the construction of efficient chemical solvers, discusses several families of algorithms, presents strategies for increasing computational efficiency, and gives insi...

  15. Influence of Zn (II) ion on abrasive-free polishing of hard disk substrate

    Energy Technology Data Exchange (ETDEWEB)

    Lei, Hong, E-mail: hong_lei2005@163.com; Zhao, Rong, E-mail: zr890804@163.com; Chen, Ruling, E-mail: chen_ruling@163.com

    2014-07-01

    With higher requirement setting for hard disk substrate to minimize roughness and defects of the polished surface, abrasive-free polishing (AFP) of hard disk substrate has been put forward in this paper. The effect of Zn (II) ion on the AFP of hard disk substrate in the H{sub 2}O{sub 2} based slurry was investigated by AFP tests. The results indicate that the material removal rate of hard disk substrate polished in slurry with Zn (II) ion is obviously higher than that without Zn (II) ion. And surface polished by slurry containing Zn (II) ion exhibits lower surface roughness and fewer nano-asperity peaks than that without Zn (II) ion. Furthermore, the acting mechanism of Zn (II) ion in AFP of hard disk substrate was analyzed. X-ray photoelectron spectroscopy analysis shows that metal Zn appears on the polished surface, implying the tribochemistry reaction occurs during AFP. The electrochemical reaction between metal Zn and oxide film Ni{sub 2}O{sub 3} on the surface of hard disk substrate during AFP can promote the chemical effect in AFP and lead to the increasing of material removal rate. - Highlights: • Zn (II) ion improves surface quality in abrasive-free polishing (AFP). • The removal rate increases with the increasing of Zn (II) ion content. • Tribo-chemistry reaction exists during AFP. • Zn (II) ion accelerates the electrochemistry reaction during AFP.

  16. Micro-effects of surface polishing treatment on microscopic field enhancement and long vacuum gap breakdown

    Science.gov (United States)

    Zhang, Yu; Su, Jiancang; Qiu, Xudong; Li, Rui; Zhao, Liang; Cheng, Jie; Zeng, Bo

    2016-09-01

    In this paper, three surface polishing treatments were employed to treat plate titanium electrodes, and microscopic surfaces of the electrodes after polishing were presented. Through comparing the breakdown strength of the 2.5 cm vacuum gap formed by plate titanium electrodes after the three treatments, experimental results showed that the breakdown strength was enhanced by 35% while the micro-surface roughness dropped from 3.5μm to 0.35μm. In view of that, effects of microstructural parameters after polishing on the microscopic field enhancement factor were investigated. The field-uniformity mechanism and the shield effect between micro-protrusions on the rough electrode surface were put forward and demonstrated. Based on the idea that electric field can be shield in a pit, a theoretical model was established to evaluate the maximum field enhancement factor βEmax on the micro-surface. It revealed that 1 ≤ βEmax ≤ 3.96, and βEmax had the maximum decrements of 1.96 and 2.1 both from 3.96 after the mirror polishing and the chemical polishing, respectively. When the surface roughness decreased to the scale from nm to μm, the effort on βEmax reduction through surface polishing was not effective to enhance the vacuum gap breakdown strength any more.

  17. Optimization of Polishing Parameters with Taguchi Method for LBO Crystal in CMP

    Institute of Scientific and Technical Information of China (English)

    Jun Li; Yongwei Zhu; Dunwen Zuo; Yong Zhu; Chuangtian Chen

    2009-01-01

    Chemical mechanical polishing (CMP) was used to polish Lithium triborate (UB_3O_5 or LBO) crystal. Taguchi method was applied for optimization of the polishing parameters. Material removal rate (MRR) and surface roughness are considered as criteria for the optimization. The polishing pressure, the abrasive concentration and the table velocity are important parameters which influence MRR and surface roughness in CMP of LBO crystal. Experiment results indicate that for MRR the polishing pressure is the most significant polishing parameter followed by table velocity; while for the surface roughness, the abrasive concentration is the most important one. For high MRR in CMP of LBO crystal the optimal conditions are: pressure 620 g/cm~2, concentration 5.0 wt pct, and velocity 60 r/min, respectively. For the best surface roughness the optimal conditions are: pressure 416 g/cm~2, concentration 5.0 wt pct, and velocity 40 r/min, respectively. The contributions of individual parameters for MRR and surface roughness were obtained.

  18. Effect of additives for higher removal rate in lithium niobate chemical mechanical planarization

    International Nuclear Information System (INIS)

    High roughness and a greater number of defects were created by lithium niobate (LN; LiNbO3) processes such as traditional grinding and mechanical polishing (MP), should be decreased for manufacturing LN device. Therefore, an alternative process for gaining defect-free and smooth surface is needed. Chemical mechanical planarization (CMP) is suitable method in the LN process because it uses a combination approach consisting of chemical and mechanical effects. First of all, we investigated the LN CMP process using commercial slurry by changing various process conditions such as down pressure and relative velocity. However, the LN CMP process time using commercial slurry was long to gain a smooth surface because of lower material removal rate (MRR). So, to improve the material removal rate (MRR), the effects of additives such as oxidizer (hydrogen peroxide; H2O2) and complexing agent (citric acid; C6H8O7) in a potassium hydroxide (KOH) based slurry, were investigated. The manufactured slurry consisting of H2O2-citric acid in the KOH based slurry shows that the MRR of the H2O2 at 2 wt% and the citric acid at 0.06 M was higher than the MRR for other conditions.

  19. Thyroid disrupting chemicals: Mechanisms and mixtures

    Science.gov (United States)

    Environmental contaminants are known to act as thyroid disrupting chemicals (TDCs). Broadly defined, TDCs are xenobiotics that alter the structure or function of the thyroid gland, alter regulatory enzymes associated with thyroid hormone (TH) homeostasis, or change circulating o...

  20. MORPHOLOGY CONTROL OF ULTRAFINE CeO2 AND ITS POLISHING EFFICACY

    Institute of Scientific and Technical Information of China (English)

    Chen Jianqing; Chen Zhigang; Li Jinchun

    2005-01-01

    Homogenous precipitation and subsequent calcination has been used to synthesize ultrafine ceria from cerium nitrate and urea solution. The ceria calcined from the precursor inherit the size and morphology of it. The size and morphology of the precursor are closely related to the preparation process. The morphology, size and distribution of the precursor could be tailored by changing the reaction condition and the ageing time. Monodispersed 200 nm sized spherical particles is prepared by this method. The powder is used in the chemical-mechanical polishing of Si wafer. The average surface roughness of the polished Si wafer is 0.171 nm measured by AFM.

  1. Physical Chemistry Chemical Kinetics and Reaction Mechanism

    CERN Document Server

    Trimm, Harold H

    2011-01-01

    Physical chemistry covers diverse topics, from biochemistry to materials properties to the development of quantum computers. Physical chemistry applies physics and math to problems that interest chemists, biologists, and engineers. Physical chemists use theoretical constructs and mathematical computations to understand chemical properties and describe the behavior of molecular and condensed matter. Their work involves manipulations of data as well as materials. Physical chemistry entails extensive work with sophisticated instrumentation and equipment as well as state-of-the-art computers. This

  2. A model for chemically-induced mechanical loading on MEMS

    DEFF Research Database (Denmark)

    Amiot, Fabien

    2007-01-01

    The development of full displacement field measurements as an alternative to the optical lever technique to measure the mechanical response for microelectro-mechanical systems components in their environment calls for a modeling of chemically-induced mechanical fields (stress, strain, and displac...

  3. Micro-structural analysis of local damage introduced in subsurface regions of 4H-SiC wafers during chemo-mechanical polishing

    Science.gov (United States)

    Sako, Hideki; Matsuhata, Hirofumi; Sasaki, Masayuki; Nagaya, Masatake; Kido, Takanori; Kawata, Kenji; Kato, Tomohisa; Senzaki, Junji; Kitabatake, Makoto; Okumura, Hajime

    2016-04-01

    The surface morphology and lattice defect structures in the subsurface regions of 4H-SiC wafers introduced during chemo-mechanical polishing (CMP) were studied by scanning electron microscopy and transmission electron microscopy. It is known that local damage consisting of high-density lattice defects is introduced in the wafers during the current CMP, however, optical microscopy showed that the surface was very flat and clean without any presence of surface defects. Specifically, this study focused on the detailed analysis of such lattice defect structures. The high-density lattice defects locally introduced in the subsurface regions consisted of nano-scale surface scratches, high-density basal-plane dislocation loops, Shockley-type stacking faults, and Y-shaped defects. Two types of dislocation loops were introduced near the scratches that were selected for further study: nearly perfect basal-plane dislocations, which were accompanied by narrow stacking faults, and apparent partial basal-plane dislocations, which were accompanied by wide stacking faults. A Y-shaped defect was observed in the local damage along the [ 11 2 ¯ 0 ] direction, but not in the local damage along the [ 1 ¯100 ] direction. It was also found that the directions of the Burgers vectors for the basal-plane dislocations clearly depended on the directions of the introduced scratch-like defects.

  4. The Application of Bileaflet Mechanical Heart Valves in the Polish Ventricular Assist Device: Physical and Numerical Study and First Clinical Usage.

    Science.gov (United States)

    Malota, Zbigniew; Sadowski, Wojciech; Krzyskow, Marek; Stolarzewicz, Bogdan

    2016-03-01

    The Polish ventricular assist device (Polvad) has been used successfully in clinical contexts for many years. The device contains two single-disc valves, one at the inlet and one at the outlet connector of the pneumatic pump. Unfortunately, in recent years, a problem has occurred with the availability of single-disc valves. This article presents the possibility of using bileaflet mechanical heart valve prostheses in the Polvad to avoid a discontinuity in clinical use. The study is based on experimental and numerical simulations and comparison of the distribution of flow, pressure, and stress (wall, shear, and turbulent) inside the Polvad chamber and the inlet/outlet connectors fitted with Sorin Monodisc and Sorin Bicarbon Fitline valves. The type and orientation of the inlet valve affects valve performance and flow distribution inside the chamber. Near-wall flow is observed for single-disc valves. In the case of bileaflet valves, the main jet is directed more centrally, with lower shear stress but higher turbulent stress in comparison with single-disc valves. For clinical usage, a 45° orientation of the bileaflet inlet valve was chosen, as this achieves good washing of the inlet area near the membrane paste surface. The Polvad with bileaflet valves has now been used successfully in our clinic for over a year and will continue to be used until new assist devices for heart support are developed.

  5. The effect of hydrogen peroxide on polishing removal rate in CMP with various abrasives

    Science.gov (United States)

    Manivannan, R.; Ramanathan, S.

    2009-01-01

    The effect of hydrogen peroxide in chemical mechanical planarization slurries for shallow trench isolation was investigated. The various abrasives used in this study were ceria, silica, alumina, zirconia, titania, silicon carbide, and silicon nitride. Hydrogen peroxide suppresses the polishing of silicon dioxide and silicon nitride surfaces by ceria abrasives. The polishing performances of other abrasives were either unaffected or enhanced slightly with the addition of hydrogen peroxide. The ceria abrasives were treated with hydrogen peroxide, and the polishing of the work surfaces with the treated abrasive shows that the inhibiting action of hydrogen peroxide is reversible. It was found that the effect of hydrogen peroxide as an additive is a strong function of the nature of the abrasive particle.

  6. Chemical kinetic reaction mechanism for the combustion of propane

    Science.gov (United States)

    Jachimowski, C. J.

    1984-01-01

    A detailed chemical kinetic reaction mechanism for the combustion of propane is presented and discussed. The mechanism consists of 27 chemical species and 83 elementary chemical reactions. Ignition and combustion data as determined in shock tube studies were used to evaluate the mechanism. Numerical simulation of the shock tube experiments showed that the kinetic behavior predicted by the mechanism for stoichiometric mixtures is in good agrement with the experimental results over the entire temperature range examined (1150-2600K). Sensitivity and theoretical studies carried out using the mechanism revealed that hydrocarbon reactions which are involved in the formation of the HO2 radical and the H2O2 molecule are very important in the mechanism and that the observed nonlinear behavior of ignition delay time with decreasing temperature can be interpreted in terms of the increased importance of the HO2 and H2O2 reactions at the lower temperatures.

  7. High polishing selectivity ceria slurry for formation of top electrode in spin-transfer torque magnetic random access memory

    Energy Technology Data Exchange (ETDEWEB)

    Cui, Hao [Advanced Semiconductor Materials and Devices Development Center, Hanyang University, Seoul 133-791 (Korea, Republic of); Department of Electronics and Communication Engineering, Hanyang University, Seoul 133-791 (Korea, Republic of); Lim, Jae-Hyung [Advanced Semiconductor Materials and Devices Development Center, Hanyang University, Seoul 133-791 (Korea, Republic of); Department of Nanoscale Semiconductor Engineering, Hanyang University, Seoul 133-791 (Korea, Republic of); Park, Jin-Hyung [Advanced Semiconductor Materials and Devices Development Center, Hanyang University, Seoul 133-791 (Korea, Republic of); Park, Jea-Gun, E-mail: parkjgL@hanyang.ac.kr [Advanced Semiconductor Materials and Devices Development Center, Hanyang University, Seoul 133-791 (Korea, Republic of); Department of Electronics and Communication Engineering, Hanyang University, Seoul 133-791 (Korea, Republic of)

    2012-11-01

    During the formation of the top electrode (T.E.) in spin-transfer torque magnetic random access memory, a slurry with a high polishing rate of SiO{sub 2} and a low polishing rate of metal (T.E. material) is required in the chemical mechanical planarization application area. We used a ceria-based slurry with a polymeric additive to maintain the high polishing rate of SiO{sub 2} while it suppresses the polishing rate of the T.E. material, tantalum and ruthenium. We found ruthenium showed a significantly higher selectivity than tantalum in the ceria-based slurry. X-ray photoelectron spectroscopy was used to investigate the adsorption characteristics of the polymeric additive on the T.E. material. Except for the adsorbed polymeric additive, we found that zeta potential of the T.E. material played a critical role in determining the polishing selectivity of SiO{sub 2}-to-T.E. material. - Highlights: Black-Right-Pointing-Pointer High selective chemical mechanical planarization (CMP) slurry was investigated. Black-Right-Pointing-Pointer The slurry has a high selectivity of SiO{sub 2}-to-metals like tantalum and ruthenium. Black-Right-Pointing-Pointer Spin-transfer-torque magnetic memory requires such high selectivity slurry. Black-Right-Pointing-Pointer Surface zeta potential was used to explain CMP mechanism. Black-Right-Pointing-Pointer tantalum and ruthenium have different rate-determining steps during CMP.

  8. Effect of mechanical stress on biofilms challenged by different chemicals.

    Science.gov (United States)

    Simões, Manuel; Pereira, Maria Olivia; Vieira, Maria João

    2005-12-01

    In this study a methodology was applied in order to ascertain the mechanical stability of biofilms, by using a stainless-steel (SS) rotating device immersed in a biological reactor where biofilms formed by Pseudomonas fluorescens were allowed to grow for 7 days at a Reynolds number of agitation of 2400. The biofilms developed with this system were characterised in terms of amount of total, extracellular and intracellular proteins and polysaccharides, amount of mass, metabolic activity and mechanical stability, showing that the biofilms were active, had a high content of extracellular constituents and an inherent mechanical stability. In order to assess the role of chemical agents on the mechanical stability, the biofilms were exposed to chemical agents followed by mechanical treatments by submission to increase Reynolds number of agitation. Seven different chemical agents were tested (two non-oxidising biocides, three surfactants and two oxidising biocides) and their effects on the biofilm mechanical stability were evaluated. The increase in the Reynolds number increased the biofilm removal, but total biofilm removal was not found for all the conditions tested. For the experiment without chemical addition (only mechanical treatment), the biofilm remaining on the surface was about 76%. The chemical treatment followed by the subsequent mechanical treatment did not remove all the biofilms from the surface. The biofilm remaining on the SS cylinder ranged from 3% to 62%, depending on the chemical treatment, showing that the chemical treatment is far from being a cause that induces massive biofilm detachment and even the synergistic chemical and mechanical treatments did not promote biofilm removal. Some chemical agents promoted an increase in the biofilm mechanical stability such as glutaraldehyde (GTA), benzalkonium chloride (BC), except for the lower concentration tested, and sodium dodecyl sulphate (SDS), except for the higher concentration tested. Treatments that

  9. Sublingual immunotherapy (SLIT)--indications, mechanism, and efficacy: Position paper prepared by the Section of Immunotherapy, Polish Society of Allergy.

    Science.gov (United States)

    Jutel, Marek; Bartkowiak-Emeryk, Małgorzata; Bręborowicz, Anna; Cichocka-Jarosz, Ewa; Emeryk, Andrzej; Gawlik, Radosław; Gonerko, Paweł; Rogala, Barbara; Nowak-Węgrzyn, Anna; Samoliński, Bolesław

    2016-01-01

    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. PMID:27012173

  10. 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.

  11. 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...

  12. 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.

  13. 石灰-陶瓷抛光砖粉无机结合料的性能及机理分析%PERFORMANCE AND MECHANISM ANALYSIS OF LIME-POLISHING POWDER INORGANIC BINDER

    Institute of Scientific and Technical Information of China (English)

    王功勋; 苏达根

    2008-01-01

    将陶瓷工业废弃物抛光砖粉用作一种公路工程新型的无机结合料,并将其与粉煤灰进行对比,测试了两种结合料的强度和水稳定性,采用XRD、SEM、IR等手段分析了其水化产物及微观形貌,通过化学结合水量以及化学未溶量等试验研究了抛光砖粉的火山灰活性及水化程度.结果表明:在相同配比条件下,石灰-抛光砖粉结合料与石灰-粉煤灰结合料相比,前者的早期抗压强度略有提高,28 d抗压强度增幅明显,平均增幅达190 %,最大增幅高达210 %;前者的7 d、28 d软化系数均高于后者,具有更好的水稳定性.SEM测试进一步说明,石灰-抛光砖粉结合料生成的水化产物更多,结构更致密,在结构与性能上优于石灰-粉煤灰结合料.%An innovative approach of reusing ceramic polishing powder generated in ceramic industries to develop high performance inorganic binders was studied. Effects of polishing powder on pozzolanic ability and hydration degree were studied comparing to fly ash by X-ray diffraction (XRD),infrared spectrum (IR),scanning electron microscope (SEM) and measuring chemical combined water and chemical undissolved quantity. Results show that polishing powder has high of pozzolanic than fly ash does. Compressive strength curing 7 days of lime-polishing powder binder is slightly higher than those of lime-fly ash binder,but amplitude of strength curing 28 days is obvious high,average amplitude is up to 190% and maximal amplitude is up to 210% comparing to fly ash-lime binder. Lime-PP binder preceded lime-FA binder in intenerate index of 7 days and 28 days under the same ratio of PP (FA) to lime condition. Microstructure analysis of two binders indicated further that larger amount of hydration product is formed in lime-polishing powder binders.

  14. 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.

  15. Surface characteristics of posterior composites after polishing and toothbrushing.

    Science.gov (United States)

    van Dijken, J W; Ruyter, I E

    1987-10-01

    The surface characteristics of eight posterior and two anterior composite resins were studied by SEM and profilometric tracings. The materials included both chemically cured and light-cured resin systems. Two posterior materials were microfilled composites; the others were conventional or hybrid types. The anterior composites were of conventional and hybrid types. At various steps in the procedures the following polishing/brushing treatments were evaluated: 1) dry polishing with Sof-lex discs followed by brushing with toothpaste; and 2) wet polishing with diamond pastes of increasing fineness, followed by brushing with toothpaste. The base line before the polishing/brushing procedures was obtained by wet polishing on silicon-carbide paper (4000 grit). All materials could be polished to a comparable smoothness by the Sof-lex discs, but this polishing procedure was associated with the development of an amorphous surface layer. Polishing with diamond pastes gave various results, with a 20-fold difference in surface roughness values from the smoothest to the roughest material. Toothbrushing after polishing with the Sof-lex system increased the surface roughness for all materials, but to various degrees. The two microfilled and four of the conventional posterior composites showed comparable surface roughness values, whereas two remaining posterior and the two anterior materials showed two to three times higher surface roughness values after toothbrushing. PMID:3478939

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

    Science.gov (United States)

    Mirzaie, Mansoreh; Yasini, Esmail; Kermanshah, Hamid; Omidi, Baharan Ranjbar

    2014-01-01

    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 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 significant increase in microleakage of evaluated tooth-colored class V restorations. PMID:24688568

  17. The chemical, mechanical, and hydrological evolution of weathering granitoid

    Science.gov (United States)

    Goodfellow, Bradley W.; Hilley, George E.; Webb, Samuel M.; Sklar, Leonard S.; Moon, Seulgi; Olson, Christopher A.

    2016-08-01

    Surprisingly few studies connect the chemical, mechanical, and hydrological evolution of rock as it weathers to saprolite and soil. We assess this coevolution in granodiorite from Monterey Peninsula, California, by measuring changes in bulk chemistry, mineralogy, volumetric strain, the oxidation state of Fe in biotite crystals, tensile strength, abrasion rate, connected porosity, and hydraulic conductivity in samples covering a range of weathering grades. We identify the oxidative dissolution of biotite as the key chemical reaction because of the volumetric expansion that accompanies formation of altered biotite and precipitation of ferrihydrite. We show how the associated accumulation of elastic strain produces an energy density that is sufficient to support rock fracturing over length scales equivalent to constituent crystals. The resulting intragranular and intergranular cracking profoundly reduces tensile strength and increases the abrasion rate, connected porosity, and hydraulic conductivity of the rock matrix. These changes increase the rate of plagioclase weathering, and ultimately the rock disintegrates into grus and clay. Major changes in rock properties can occur with only minor element leaching, and the threshold behavior of weathering that arises from the coevolution of chemical, hydrological, and mechanical properties may be difficult to capture using simplified weathering models that fail to incorporate these properties. Our results, which combine the mechanical and hydrological evolution of weathering rock with more common measurements of chemical changes, should help to more accurately model the effects of, and mechanical and hydrological feedbacks upon, chemical weathering of rock.

  18. 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.

  19. Effect of Pad Surface Micro-Texture on Removal Rate during Interlayer Dielectric Chemical Mechanical Planarization Process

    Science.gov (United States)

    Liao, Xiaoyan; Zhuang, Yun; Borucki, Leonard J.; Cheng, Jiang; Theng, Siannie; Ashizawa, Toranosuke; Philipossian, Ara

    2013-01-01

    The effect of pad surface micro-texture on removal rate in interlayer dielectric chemical mechanical planarization was investigated. Blanket 200-mm oxide wafers were polished on a Dow® IC1000TM K-groove pad conditioned at two different conditioning forces. The coefficient of friction increased slightly (by 7%) while removal rate increased dramatically (by 65%) when conditioning force was increased from 26.7 to 44.5 N. Pad surface micro-texture analysis results showed that pad surface contact area decreased dramatically (by 71%) at the conditioning force of 44.5 N, leading to a sharp increase in the local contact pressure and resulting in a significantly higher removal rate.

  20. Removal Of Optical Coatings Without Polishing

    Science.gov (United States)

    Gourley, Helen

    1980-11-01

    A process for removing antireflection, mirror and polarizer coatings has been developed at ILC, based on work begun by LLL (Applied Optics Vol. 17, No. 12, 15 June 1978 - "Notes on Optical Coating Removal", N.J. Brown). Because of the danger (personnel hazard) involved in the hydrofluoric acid process, we employed an ammonium bifluoride solution, combined with various polishing components. The substrates, generally BK7, are fairly soft and also sensitive to chemical action. Therefore we have limited our polishing materials to aluminum oxide powder graded at 0.1 pm or smaller. For some coatings, no polishing material is used, as the ammonium bifluoride solution is adequate to remove the coating. The resulting clean surface is washed and neutralized, and is then ready for recoating.

  1. New directions: Atmospheric chemical mechanisms for the future

    Science.gov (United States)

    Kaduwela, Ajith; Luecken, Deborah; Carter, William; Derwent, Richard

    2015-12-01

    The atmospheric chemical reaction scheme, commonly referred to as the chemical mechanism, is the portion of an air quality model that represents the atmospheric chemistry of the pollutants. It is at the heart of every air quality model used in research and policy applications to predict and analyse the complex air pollutants: ozone, air toxics and PM2.5. The chemical mechanism should incorporate available information on chemical kinetics and reaction pathways and be the conduit through which the fundamental science of atmospheric chemistry is applied to solve real-world problems. The efficiency and effectiveness of policies developed to reduce exposure to harmful pollutants depend on how well the mechanisms reflect the actual chemistry. If the mechanism has reaction pathways that are incorrectly characterised or completely missing, the resulting predictions may underestimate emission reduction requirements needed to meet public health and ecosystem protection targets, or may overstate the emission reductions needed and cause unnecessary implementation costs. It is therefore essential that mechanisms utilise the best, most up-to-date atmospheric chemistry information available so that policy development is based on air quality model predictions that are robust, transparent and free from scientific challenge. We are concerned that this may not continue to be the case.

  2. Characterization of Chemical and Mechanical Properties of Polymer Based Nanocomposites

    OpenAIRE

    Wafy, Tamer

    2013-01-01

    Characterization of Chemical and Mechanical Properties of Polymer Based NanocompositesThe University of ManchesterTamer Wafy Doctor of Philosophy17 January, 2013One of the most significant issues in nanocomposite performance is improving the dispersion of carbon nanotubes (CNTs) in thermosetting or thermoplastic polymers in order to gain good mechanical properties. Several studies have investigated the fabrication of nanocomposites based on carbon nanotubes and analysed properties, but there ...

  3. Quantum chemical investigation of mechanisms of silane oxidation

    DEFF Research Database (Denmark)

    Mader, Mary M.; Norrby, Per-Ola

    2001-01-01

    Several mechanisms for the peroxide oxidation of organosilanes to alcohols are compared by quantum chemical calculations, including solvation with the PCM method. Without doubt, the reaction proceeds via anionic, pentacoordinate silicate species, but a profound difference is found between in vacuo...

  4. Environmentally clean slurry using nano-TiO{sub 2}-abrasive mixed with oxidizer H{sub 2}O{sub 2} for ruthenium-film chemical mechanical planarization

    Energy Technology Data Exchange (ETDEWEB)

    Cui, Hao [Department of Electronics and Communications Engineering, Hanyang University, Seoul 133-791 (Korea, Republic of); Advance Semiconductor Material and Device Development Center, Hanyang University, Seoul 133-791 (Korea, Republic of); Park, Jin-Hyung [Advance Semiconductor Material and Device Development Center, Hanyang University, Seoul 133-791 (Korea, Republic of); Park, Jea-Gun, E-mail: parkjgL@hanyang.ac.kr [Department of Electronics and Communications Engineering, Hanyang University, Seoul 133-791 (Korea, Republic of); Advance Semiconductor Material and Device Development Center, Hanyang University, Seoul 133-791 (Korea, Republic of)

    2013-10-01

    A colloidal silica-abrasive-based slurry mixed with periodate salts has been used for chemical mechanical planarization (CMP) of ruthenium (Ru) film in semiconductor-chip fabrication. This slurry has serious environmental problems such as generation of toxic RuO{sub 4} gas, corrosion, and ionic contamination. We developed an environmentally clean slurry using nano-TiO{sub 2} abrasive mixed with hydrogen peroxide (H{sub 2}O{sub 2}) for the purpose of Ru-film CMP. Moreover, this slurry is free of corrosion and ionic contamination. The polishing rates of Ru and SiO{sub 2} films with this slurry strongly depended on the H{sub 2}O{sub 2} concentration; the Ru-film polishing rate rapidly increased with H{sub 2}O{sub 2} concentration up to 1 wt% and then slightly decreased or saturated, whereas the SiO{sub 2}-film polishing rate abruptly dropped to ∼50 Å/min. In particular, the adsorbed amount of H{sub 2}O{sub 2} on nano-TiO{sub 2} abrasive directly determined the Ru-film polishing rate, indicating a new CMP mechanism of Ru film in the slurry.

  5. Multi-functional composite materials for catalysis and chemical mechanical planarization

    Science.gov (United States)

    Coutinho, Cecil A.

    2009-12-01

    Composite materials formed from two or more functionally different materials offer a versatile avenue to create a tailored material with well defined traits. Within this dissertation research, multi-functional composites were synthesized based on organic and inorganic materials. The functionally of these composites was experimentally tested and a semi-empirical model describing the sedimentation behavior of these particles was developed. This first objective involved the fabrication of microcomposites consisting of titanium dioxide (TiO2) nanoparticles confined within porous, microgels of a thermo-responsive polymer for use in the photocatalytic treatment of wastewater. TiO2 has been shown to be an excellent photocatalyst with potential applications in advanced oxidative processes such as wastewater remediation. Upon UV irradiation, short-lived electron-hole pairs are generated, which produce oxidative species that degrade simple organic contaminants. The rapid sedimentation of these microcomposites provided an easy gravimetric separation after remediation. Methyl orange was used as a model organic contaminant to investigate the kinetics of photodegradation under a range of concentrations and pH conditions. Although after prolonged periods of UV irradiation (˜8-13 hrs), the titania-microgels also degrade, regeneration of the microcomposites was straightforward via the addition of polymer microgels with no loss in photocatalytic activity of the reformed microcomposites. The second objective within this dissertation involved the systematic development of abrasive microcomposite particles containing well dispersed nanoparticles of ceria in an organic/inorganic hybrid polymeric particle for use in chemical mechanical polishing/planarization (CMP). A challenge in IC fabrication involves the defect-free planarization of silicon oxide films for successful multi-layer deposition. Planarization studies conducted with the microcomposites prepared in this research, yield

  6. Fluid Jet Polishing

    NARCIS (Netherlands)

    Booij, S.M.

    2003-01-01

    The goal of this thesis research was to investigate the possibilities and limitations of the Fluid Jet Polishing (FJP) technique. FJP is a new optical fabrication technique that is capable of making shape corrections and reducing the surface roughness of glass and other materials. The principle of o

  7. Modulation of mechanical resonance by chemical potential oscillation in graphene

    Science.gov (United States)

    Chen, Changyao; Deshpande, Vikram V.; Koshino, Mikito; Lee, Sunwoo; Gondarenko, Alexander; MacDonald, Allan H.; Kim, Philip; Hone, James

    2016-03-01

    The classical picture of the force on a capacitor assumes a large density of electronic states, such that the electrochemical potential of charges added to the capacitor is given by the external electrostatic potential and the capacitance is determined purely by geometry. Here we consider capacitively driven motion of a nano-mechanical resonator with a low density of states, in which these assumptions can break down. We find three leading-order corrections to the classical picture: the first of which is a modulation in the static force due to variation in the internal chemical potential; the second and third are changes in the static force and dynamic spring constant due to the rate of change of chemical potential, expressed as the quantum (density of states) capacitance. As a demonstration, we study capacitively driven graphene mechanical resonators, where the chemical potential is modulated independently of the gate voltage using an applied magnetic field to manipulate the energy of electrons residing in discrete Landau levels. In these devices, we observe large periodic frequency shifts consistent with the three corrections to the classical picture. In devices with extremely low strain and disorder, the first correction term dominates and the resonant frequency closely follows the chemical potential. The theoretical model fits the data with only one adjustable parameter representing disorder-broadening of the Landau levels. The underlying electromechanical coupling mechanism is not limited by the particular choice of material, geometry, or mechanism for variation in the chemical potential, and can thus be extended to other low-dimensional systems.

  8. Development and Validation of Chemical Kinetic Mechanism Reduction Scheme for Large-Scale Mechanisms

    DEFF Research Database (Denmark)

    Poon, Hiew Mun; Ng, Hoon Kiat; Gan, Suyin;

    2014-01-01

    This work is an extension to a previously reported work on chemical kinetic mechanism reduction scheme for large-scale mechanisms. Here, Perfectly Stirred Reactor (PSR) was added as a criterion of data source for mechanism reduction instead of using only auto-ignition condition. As a result......, a reduced n-hexadecane mechanism with 79 species for diesel fuel surrogate was successfully derived from the detailed mechanism. Following that, the reduced n-hexadecane mechanism was validated under auto-ignition and PSR conditions using zero-dimensional (0-D) closed homogeneous batch reactor in CHEMKIN...

  9. Coupled Thermal-Chemical-Mechanical Modeling of Validation Cookoff Experiments

    Energy Technology Data Exchange (ETDEWEB)

    ERIKSON,WILLIAM W.; SCHMITT,ROBERT G.; ATWOOD,A.I.; CURRAN,P.D.

    2000-11-27

    The cookoff of energetic materials involves the combined effects of several physical and chemical processes. These processes include heat transfer, chemical decomposition, and mechanical response. The interaction and coupling between these processes influence both the time-to-event and the violence of reaction. The prediction of the behavior of explosives during cookoff, particularly with respect to reaction violence, is a challenging task. To this end, a joint DoD/DOE program has been initiated to develop models for cookoff, and to perform experiments to validate those models. In this paper, a series of cookoff analyses are presented and compared with data from a number of experiments for the aluminized, RDX-based, Navy explosive PBXN-109. The traditional thermal-chemical analysis is used to calculate time-to-event and characterize the heat transfer and boundary conditions. A reaction mechanism based on Tarver and McGuire's work on RDX{sup 2} was adjusted to match the spherical one-dimensional time-to-explosion data. The predicted time-to-event using this reaction mechanism compares favorably with the validation tests. Coupled thermal-chemical-mechanical analysis is used to calculate the mechanical response of the confinement and the energetic material state prior to ignition. The predicted state of the material includes the temperature, stress-field, porosity, and extent of reaction. There is little experimental data for comparison to these calculations. The hoop strain in the confining steel tube gives an estimation of the radial stress in the explosive. The inferred pressure from the measured hoop strain and calculated radial stress agree qualitatively. However, validation of the mechanical response model and the chemical reaction mechanism requires more data. A post-ignition burn dynamics model was applied to calculate the confinement dynamics. The burn dynamics calculations suffer from a lack of characterization of the confinement for the flaw

  10. Chemical dynamics in the gas phase: Time-dependent quantum mechanics of chemical reactions

    Energy Technology Data Exchange (ETDEWEB)

    Gray, S.K. [Argonne National Laboratory, IL (United States)

    1993-12-01

    A major goal of this research is to obtain an understanding of the molecular reaction dynamics of three and four atom chemical reactions using numerically accurate quantum dynamics. This work involves: (i) the development and/or improvement of accurate quantum mechanical methods for the calculation and analysis of the properties of chemical reactions (e.g., rate constants and product distributions), and (ii) the determination of accurate dynamical results for selected chemical systems, which allow one to compare directly with experiment, determine the reliability of the underlying potential energy surfaces, and test the validity of approximate theories. This research emphasizes the use of recently developed time-dependent quantum mechanical methods, i.e. wave packet methods.

  11. Chemical reactions modulated by mechanical stress: extended Bell theory.

    Science.gov (United States)

    Konda, Sai Sriharsha M; Brantley, Johnathan N; Bielawski, Christopher W; Makarov, Dmitrii E

    2011-10-28

    A number of recent studies have shown that mechanical stress can significantly lower or raise the activation barrier of a chemical reaction. Within a common approximation due to Bell [Science 200, 618 (1978)], this barrier is linearly dependent on the applied force. A simple extension of Bell's theory that includes higher order corrections in the force predicts that the force-induced change in the activation energy will be given by -FΔR - ΔχF(2)∕2. Here, ΔR is the change of the distance between the atoms, at which the force F is applied, from the reactant to the transition state, and Δχ is the corresponding change in the mechanical compliance of the molecule. Application of this formula to the electrocyclic ring-opening of cis and trans 1,2-dimethylbenzocyclobutene shows that this extension of Bell's theory essentially recovers the force dependence of the barrier, while the original Bell formula exhibits significant errors. Because the extended Bell theory avoids explicit inclusion of the mechanical stress or strain in electronic structure calculations, it allows a computationally efficient characterization of the effect of mechanical forces on chemical processes. That is, the mechanical susceptibility of any reaction pathway is described in terms of two parameters, ΔR and Δχ, both readily computable at zero force.

  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. A multipurpose reduced chemical-kinetic mechanism for methanol combustion

    Science.gov (United States)

    Fernández-Tarrazo, Eduardo; Sánchez-Sanz, Mario; Sánchez, Antonio L.; Williams, Forman A.

    2016-07-01

    A multipurpose reduced chemical-kinetic mechanism for methanol combustion comprising 8 overall reactions and 11 reacting chemical species is presented. The development starts by investigating the minimum set of elementary reactions needed to describe methanol combustion with reasonable accuracy over a range of conditions of temperature, pressure, and composition of interest in combustion. Starting from a 27-step mechanism that has been previously tested and found to give accurate predictions of ignition processes for these conditions, it is determined that the addition of 11 elementary reactions taken from its basis (San Diego) mechanism extends the validity of the description to premixed-flame propagation, strain-induced extinction of non-premixed flames, and equilibrium composition and temperatures, giving results that compare favourably with experimental measurements and also with computations using the 247-step detailed San Diego mechanism involving 50 reactive species. Specifically, premixed-flame propagation velocities and extinction strain rates for non-premixed counterflow flames calculated with the 38-step mechanism show departures from experimental measurements and detailed-chemistry computations that are roughly on the order of 10%, comparable with expected experimental uncertainties. Similar accuracy is found in comparisons of autoignition times over the range considered, except at very high temperatures, under which conditions the computations tend to overpredict induction times for all of the chemistry descriptions tested. From this 38-step mechanism, the simplification is continued by introducing steady-state approximations for the intermediate species CH3, CH4, HCO, CH3O, CH2OH, and O, leading to an 8-step reduced mechanism that provides satisfactory accuracy for all conditions tested. The flame computations indicate that thermal diffusion has a negligible influence on methanol combustion in all cases considered and that a mixture-average species

  14. Coupling between chemical degradation and mechanical behaviour of leached concrete

    International Nuclear Information System (INIS)

    This work is in the context of the long term behavior of concrete employed in radioactive waste disposal. The objective is to study the coupled chemo-mechanical modelling of concrete. In the first part of this contribution, experimental investigations are described where the effects of the calcium leaching process of concrete on its mechanical properties are highlighted. An accelerated method has been chosen to perform this leaching process by using an ammonium nitrate solution. In the second part, we present a coupled phenomenological chemo-mechanical model that represents the degradation of concrete materials. On one hand, the chemical behavior is described by the simplified calcium leaching approach of cement paste and mortar. Then a homogenization approach using the asymptotic development is presented to take into account the influence of the presence of aggregates in concrete. And on the other hand, the mechanical part of the modelling is given. Here continuum damage mechanics is used to describe the mechanical degradation of concrete. The growth of inelastic strains observed during the mechanical tests is describes by means of a plastic like model. The model is established on the basis of the thermodynamics of irreversible processes framework. The coupled nonlinear problem at hand is addressed within the context of the finite element method. Finally, numerical simulations are compared with the experimental results for validation. (author)

  15. Polish Nuclear Physics Network

    International Nuclear Information System (INIS)

    In June 2002 the representatives of thirteen Polish nuclear physics units decided to create Polish Nuclear Physics Network (PNPN) and to contact Czech Republic, Hungary and Slovakia with a suggestion to establish a larger network of nuclear physics laboratories in these countries and in Poland. In spring 2003 North-East European Network (NEEN) was established. Its planned networking activities, their objectives and expected outcomes were submitted to EURONS Coordinator. During the same period the nuclear physics laboratories from Bulgaria, Croatia, Greece, Romania, Serbia and Turkey formed South-East European Network (SEEN) and also applied for EURONS support. Eventually, following the EURONS advice, the merge of NEEN and SEEN was decided by representatives of both networks and, in 2004, a common network EWON (East - West Outreach) was included in the EURONS initiative. The indicated EU financial contribution to EWON includes only the support of NEEN, whereas SEEN, for practical reasons, is financed separately. The nuclear physics activity in Poland can be conveniently divided into a few subgroups: - experimental nuclear physics using local facilities; - experimental nuclear physics using external facilities; - theoretical nuclear physics; - applications of nuclear physics to other domains of science; - medical applications. Most of these activities are presented in this report, at least partly, in the form of review articles and short communications. The special place in the Polish nuclear physics landscape occupies the theoretical physics. Not limited by severe financial restrictions which affects local experimental facilities, the flourishing of this domain is especially evident in the nuclear structure theory

  16. Polish device for FOCCoS/PFS slit system

    Science.gov (United States)

    de Oliveira, Antonio Cesar; de Oliveira, Ligia Souza; de Arruda, Marcio V.; Souza Marrara, Lucas; dos Santos, Leandro Henrique; Ferreira, Décio; dos Santos, Jesulino Bispo; de Paiva Vilaça, Rodrigo; Rosa, Josimar Aparecido; Sodré Junior, Laerte; de Oliveira, Claudia Mendes

    2014-07-01

    The Fiber Optical Cable and Connector System, "FOCCoS", for the Prime Focus Spectrograph, "PFS", is responsible for transporting light from the Subaru Telescope focal plane to a set of four spectrographs. Each spectrograph will be fed by a convex curved slit with 616 optical fibers organized in a linear arrangement. The slit frontal surface is covered with a special dark composite, made with refractory oxide, which is able to sustain its properties with minimum quantities of abrasives during the polishing process; this stability is obtained This stability is obtained by the detachment of the refractory oxide nanoparticles, which then gently reinforce gently the polishing process and increase its the efficiency. The surface roughness measured in several samples after high performance polishing was about 0.01 microns. Furthermore, the time for obtaining a polished surface with this quality is about 10 times less than the time required for polishing a brass, glass or ceramic surface of the same size. In this paper, we describe the procedure developed for high quality polishing of this type of slit. The cylindrical polishing described here, uses cylindrical concave metal bases on which glass paper is based. The polishing process consists to use grid sequences of 30μm, 12μm, 9μm, 5μm, 3μm, 1μm and, finally, a colloidal silica on a chemical cloth. To obtain the maximum throughput, the surface of the fibers should be polished in such a way that they are optically flat and free from scratches. The optical fibers are inspected with a microscope at all stages of the polishing process to ensure high quality. The efficiency of the process may be improved by using a cylindrical concave composite base as a substrate suitable for diamond liquid solutions. Despite this process being completely by hand, the final result shows a very high quality.

  17. Mechanisms of fuel-cladding chemical interaction: US interpretation

    International Nuclear Information System (INIS)

    Proposed mechanisms of fuel-cladding chemical interaction (FCCI) in LMFBR fuel pins are reviewed and examined in terms of in-pile and out-of-pile data. From this examination several factors are identified which may govern the occurrence of localized deep intergranular penetrations of Type-316SS cladding. Using a plausible mechanistic hypothesis for FCCI, first steps have been taken towards developing a quantitative, physically-meaningful, mathematical method of predicting cladding wastage in operating fuel pins. Both kinetic and thermodynamic aspects of FCCI are considered in the development of this prediction method, together with a fuel chemistry model that describes the evolution of thermochemical conditions at the fuel-cladding gap. On the basis of results from recent fuel pin and laboratory tests a thermal transport mechanism has been proposed to explain the thermal gradient-induced migration of Fe, Cr, and Ni from cladding into the fuel. This mechanism involves chemical transport of the metallic cladding components (as tellurides) in liquid Cs-Te. (author)

  18. Computational thermal, chemical, fluid, and solid mechanics for geosystems management.

    Energy Technology Data Exchange (ETDEWEB)

    Davison, Scott; Alger, Nicholas; Turner, Daniel Zack; Subia, Samuel Ramirez; Carnes, Brian; Martinez, Mario J.; Notz, Patrick K.; Klise, Katherine A.; Stone, Charles Michael; Field, Richard V., Jr.; Newell, Pania; Jove-Colon, Carlos F.; Red-Horse, John Robert; Bishop, Joseph E.; Dewers, Thomas A.; Hopkins, Polly L.; Mesh, Mikhail; Bean, James E.; Moffat, Harry K.; Yoon, Hongkyu

    2011-09-01

    This document summarizes research performed under the SNL LDRD entitled - Computational Mechanics for Geosystems Management to Support the Energy and Natural Resources Mission. The main accomplishment was development of a foundational SNL capability for computational thermal, chemical, fluid, and solid mechanics analysis of geosystems. The code was developed within the SNL Sierra software system. This report summarizes the capabilities of the simulation code and the supporting research and development conducted under this LDRD. The main goal of this project was the development of a foundational capability for coupled thermal, hydrological, mechanical, chemical (THMC) simulation of heterogeneous geosystems utilizing massively parallel processing. To solve these complex issues, this project integrated research in numerical mathematics and algorithms for chemically reactive multiphase systems with computer science research in adaptive coupled solution control and framework architecture. This report summarizes and demonstrates the capabilities that were developed together with the supporting research underlying the models. Key accomplishments are: (1) General capability for modeling nonisothermal, multiphase, multicomponent flow in heterogeneous porous geologic materials; (2) General capability to model multiphase reactive transport of species in heterogeneous porous media; (3) Constitutive models for describing real, general geomaterials under multiphase conditions utilizing laboratory data; (4) General capability to couple nonisothermal reactive flow with geomechanics (THMC); (5) Phase behavior thermodynamics for the CO2-H2O-NaCl system. General implementation enables modeling of other fluid mixtures. Adaptive look-up tables enable thermodynamic capability to other simulators; (6) Capability for statistical modeling of heterogeneity in geologic materials; and (7) Simulator utilizes unstructured grids on parallel processing computers.

  19. Mechanism of radiation-chemical and pyrolytic transformations in lexan

    OpenAIRE

    Roustam Aliev; Rafael Navarro-González

    2006-01-01

    We report here a new approach to study the mechanism of radiation-chemical transformations in polymeric materials based on the combined analysis of radiolytic gases, and pyrolytic products from preirradiated polymers by flash pyrolysis coupled to gas chromatography –Fourier transformed infrared spectroscopy– mass spectrometry with electron impact mode (GC-FTIR-MS). Lexan® (bisphenol-A polycarbonate) was studied in the dose range from 0.125 to 1.0 MGy. Lexan irradiation was accompanied by the ...

  20. Development of a hybrid chemical/mechanical heat pump

    Science.gov (United States)

    Grzyll, Lawrence R.; Silvestri, John J.; Scaringe, Robert P.

    1991-01-01

    The authors present the current development status of a hybrid chemical/mechanical heat pump for low-lift applications. The heat pump provides electronics cooling by evaporating a pure refrigerant from an absorbent/refrigerant mixture in a generator/cold plate. The current development focused on evaluation of absorbent/refrigerant pairs, corrosion testing, pump and compressor design, and electronic cold plate design. Two cycle configurations were considered. The first configuration utilized a standard mechanical compressor and pump. The second cycle configuration investigated pumps and compressors with non-moving parts. An innovative generator/cold plate design is also presented. The development to date shows that this cycle has about the same performance as standard vapor compression heat pumps with standard refrigerants but may have some performance and reliability advantages over vapor compression heat pumps.

  1. Contrastive Analysis of Metatext. Expressing Polish "niemniej" in Bulgarian

    Directory of Open Access Journals (Sweden)

    Anna Katarzyna Kisiel

    2015-12-01

    Full Text Available Contrastive Analysis of Metatext. Expressing Polish niemniej in BulgarianThe author discusses possible ways of expressing meanings of Polish niemniej, tym niemniej and niemniej jednak in Bulgarian. A confrontative analysis of the equivalents gives grounds for a reflection on how to conduct a cross-linguistic examination of metatext. Two important questions are raised: whether it is methodologically justified to compare objects non-identical such as units and compositions, lexical and grammatical means, and what exactly equivalence within metatext class means. It is expected that analysis of metatext in Polish and Bulgarian will allow to discover mechanisms of creating metatextual units.

  2. Influence of oxygen on the chemical stage of radiobiological mechanism

    Science.gov (United States)

    Barilla, Jiří; Lokajíček, Miloš V.; Pisaková, Hana; Simr, Pavel

    2016-07-01

    The simulation of the chemical stage of radiobiological mechanism may be very helpful in studying the radiobiological effect of ionizing radiation when the water radical clusters formed by the densely ionizing ends of primary or secondary charged particle may form DSBs damaging DNA molecules in living cells. It is possible to study not only the efficiency of individual radicals but also the influence of other species or radiomodifiers (mainly oxygen) being present in water medium during irradiation. The mathematical model based on Continuous Petri nets (proposed by us recently) will be described. It makes it possible to analyze two main processes running at the same time: chemical radical reactions and the diffusion of radical clusters formed during energy transfer. One may study the time change of radical concentrations due to the chemical reactions running during diffusion process. Some orientation results concerning the efficiency of individual radicals in DSB formation (in the case of Co60 radiation) will be presented; the influence of oxygen present in water medium during irradiation will be shown, too.

  3. Centrifugal barrel polishing of 1.3 GHz Nb cavities

    Energy Technology Data Exchange (ETDEWEB)

    Tamashevich, Yegor; Foster, Brian [DESY, Hamburg (Germany); Hamburg Univ. (Germany); Navitski, Aliaksandr; Steder, Lea; Elsen, Eckhard [DESY, Hamburg (Germany)

    2013-07-01

    Superconducting radio-frequency (SRF) cavities are the key components of particle accelerators such as the European X-ray Free Electron Laser (XFEL, under construction) and the planned future International Linear Collider (ILC). Steady progress in surface treatment techniques of SRF cavities in both the achievable quality factor Q and the accelerating electric field Eacc makes new accelerators and ambitious projects feasible. One of the alternative surface preparation techniques which is actually being explored is centrifugal barrel polishing (CBP) pioneered at KEK in Japan in mid-nineties by T. Hiuchi et al. CBP is a mechanical polishing of cavities and results in around 10 x smaller surface roughness and mirror-like surface as compared to chemistry alone. Q and E{sub acc} are expected to be at least as high as for chemically treated cavities. CBP eliminates the bulk chemistry and has the potential to completely replace the chemistry. The University of Hamburg is installing a CBP machine to study it as a cavity preparation and repair technique for 9-cell 1.3 GHz SRF cavities at the Deutsche Elektronen-Synchrotron (DESY). The setup and first commissioning tests will be presented and discussed.

  4. Detailed chemical kinetic oxidation mechanism for a biodiesel surrogate

    Energy Technology Data Exchange (ETDEWEB)

    Herbinet, O; Pitz, W J; Westbrook, C K

    2007-09-20

    A detailed chemical kinetic mechanism has been developed and used to study the oxidation of methyl decanoate, a surrogate for biodiesel fuels. This model has been built by following the rules established by Curran et al. for the oxidation of n-heptane and it includes all the reactions known to be pertinent to both low and high temperatures. Computed results have been compared with methyl decanoate experiments in an engine and oxidation of rapeseed oil methyl esters in a jet stirred reactor. An important feature of this mechanism is its ability to reproduce the early formation of carbon dioxide that is unique to biofuels and due to the presence of the ester group in the reactant. The model also predicts ignition delay times and OH profiles very close to observed values in shock tube experiments fueled by n-decane. These model capabilities indicate that large n-alkanes can be good surrogates for large methyl esters and biodiesel fuels to predict overall reactivity, but some kinetic details, including early CO{sub 2} production from biodiesel fuels, can be predicted only by a detailed kinetic mechanism for a true methyl ester fuel. The present methyl decanoate mechanism provides a realistic kinetic tool for simulation of biodiesel fuels.

  5. Detailed chemical kinetic oxidation mechanism for a biodiesel surrogate

    Energy Technology Data Exchange (ETDEWEB)

    Herbinet, O; Pitz, W J; Westbrook, C K

    2007-09-17

    A detailed chemical kinetic mechanism has been developed and used to study the oxidation of methyl decanoate, a surrogate for biodiesel fuels. This model has been built by following the rules established by Curran et al. for the oxidation of n-heptane and it includes all the reactions known to be pertinent to both low and high temperatures. Computed results have been compared with methyl decanoate experiments in an engine and oxidation of rapeseed oil methyl esters in a jet stirred reactor. An important feature of this mechanism is its ability to reproduce the early formation of carbon dioxide that is unique to biofuels and due to the presence of the ester group in the reactant. The model also predicts ignition delay times and OH profiles very close to observed values in shock tube experiments fueled by n-decane. These model capabilities indicate that large n-alkanes can be good surrogates for large methyl esters and biodiesel fuels to predict overall reactivity, but some kinetic details, including early CO2 production from biodiesel fuels, can be predicted only by a detailed kinetic mechanism for a true methyl ester fuel. The present methyl decanoate mechanism provides a realistic kinetic tool for simulation of biodiesel fuels.

  6. Chemical and mechanical weed control in soybean (Glycine max

    Directory of Open Access Journals (Sweden)

    Weber, Jonas Felix

    2016-02-01

    Full Text Available In this study we investigated the possibility of chemical and mechanical weed control strategies in soybean. Soybean field experiments were carried out in 2013 and 2014 in Southern Germany. Five treatments including common herbicide mixtures and four mechanical weed control treatments, implementing a harrow and a hoe, were tested at different locations. In the herbicide experiments two treatments were applied by PRE emergence herbicides (metribuzin, clomazone, dimethenamid and metribuzin, flufenacet, clomazone and another two treatments were sprayed with a combination of PRE + POST emergence herbicides (metribuzin, flufenacet, thifensulfuron and pendimethalin, thifensulfuron, bentazone, cycloxydim. Furthermore, a POST herbicide treatment was implemented (thifensulfuron, bentazone, thifensulfuron and fluazifop-P-butyl. In the mechanical weed control experiments, treatments were: three times hoeing, PRE emergence harrowing plus three times hoeing, hoeing and harrowing in rotation or three times harrowing. In both experiments an untreated control was included. A 90% weed control efficacy and 23% yield increase was observed in the POST herbicide treatment. PRE + POST treatments resulted in 92% to 99% weed control efficiency and 15% yield increase compared to the untreated control. In the mechanical weed control experiments the combination of PRE emergence harrowing and POST emergence hoeing resulted in 82% weed control efficiency and 34% higher yield compared to the untreated control. Less weed control efficiency (72% was observed in the harrow treatment, leading to 20% higher yield compared to the control. The suitability of both strategies for implementation in “Integrated Weed Management” has been investigated.

  7. 利用DMAIC解决铝合金化学抛光制程参数的设计问题%Application of Six Sigma Method on chemical polishing process yield improvement

    Institute of Scientific and Technical Information of China (English)

    杨赟炜

    2012-01-01

    Aluminum alloy enclosure is consumer electronics customer's favourite, because it is so light, strong and good thermal conductivity. But most of the defects appear at chemical polishing process to enclosure production process. So in the paper, the DMAIC process of Six Sigma method is used to design the optimized of H3PO5 / H2SO4,Al^3+,time,temperature which are the four key factors. Good results are obtained.%铝合金外壳以其的轻薄、坚固和优良的导热性逐渐成为电子消费市场的新宠,但对铝合金外壳制造过程来说,化学抛光制程问题一直困扰着阳极处理制造商。本文采用六西格玛的DMAIC流程,通过优化组合磷酸硫酸比、Al^3+含量、化抛时间、温度对提高良率最有影响的这4点参数进行设计,从而得到较好的效果。

  8. 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

  9. Nano alumina slurries for improved polishing on thermoset and thermoplastic resins

    Science.gov (United States)

    Hooper, Abigail R.; Boffa, Christopher C.; Sarkas, Harry W.

    2015-10-01

    Cerium oxide, because of its commonality to the optical workshop, is often used as the go-to abrasive for polishing many different substrates. For silica containing substrates, cerium oxide is an excellent abrasive choice because it allows for both chemical and mechanical polishing. However, plastic lenses do not contain silica and thereby cannot undergo the same chemical reaction with cerium oxide. These substrates are also very vulnerable to sleeks and scratches, and the tabular cerium oxide can impart defects into the surface resulting in scratch-dig failures and higher than expected surface roughness values. With the recent market push for plastic optical components, selection of an appropriate polishing slurry is critical to maintaining a competitive edge in the market and a profitable business. In this paper, the authors will show how using an aluminum oxide can improve performance on thermoset and thermoplastic resins like polycarbonate, Zeonex® and Acrylica. The shape of the aluminum oxide allows for reduced defectivity while the high hardness of the abrasive allows for a removal rate tunable to the substrate hardness.

  10. Mathematically Reduced Chemical Reaction Mechanism Using Neural Networks

    Energy Technology Data Exchange (ETDEWEB)

    Ziaul Huque

    2007-08-31

    This is the final technical report for the project titled 'Mathematically Reduced Chemical Reaction Mechanism Using Neural Networks'. The aim of the project was to develop an efficient chemistry model for combustion simulations. The reduced chemistry model was developed mathematically without the need of having extensive knowledge of the chemistry involved. To aid in the development of the model, Neural Networks (NN) was used via a new network topology known as Non-linear Principal Components Analysis (NPCA). A commonly used Multilayer Perceptron Neural Network (MLP-NN) was modified to implement NPCA-NN. The training rate of NPCA-NN was improved with the GEneralized Regression Neural Network (GRNN) based on kernel smoothing techniques. Kernel smoothing provides a simple way of finding structure in data set without the imposition of a parametric model. The trajectory data of the reaction mechanism was generated based on the optimization techniques of genetic algorithm (GA). The NPCA-NN algorithm was then used for the reduction of Dimethyl Ether (DME) mechanism. DME is a recently discovered fuel made from natural gas, (and other feedstock such as coal, biomass, and urban wastes) which can be used in compression ignition engines as a substitute for diesel. An in-house two-dimensional Computational Fluid Dynamics (CFD) code was developed based on Meshfree technique and time marching solution algorithm. The project also provided valuable research experience to two graduate students.

  11. Mechanism of plasma ignition in electrothermal-chemical launcher

    Institute of Scientific and Technical Information of China (English)

    Yong JIN; Yan-jie NI; Hai-yuan LI; Bao-ming LI

    2016-01-01

    Plasma generator is a core component in an electrothermal-chemical (ETC) launcher. Its work state directly influences the launch efficiency of a system. The interaction between plasma and propellants is a very important mechanism in ETC technology. Based on the transient radiation model and open air plasma jet experiment, the mechanism of plasma ignition process is analyzed. Results show that the surface temperature of local solid propellant grain can quickly achieve the ignition temperature under the action of early transient plasma radiation. But it needs enough time to maintain the high energy flow to make self-sustained combustion of solid propellant grains. Because of the limited space characteristics of transient radiation, the near-field propellant grains can gain enough energy by the strong transient radiation to be ignited and achieve self-sustained combustion. The far-field propellant grains mainly gain the energy by the activated particles in plasma jet to be ignited and self-sustained combustion. Experiments show that plasma jet always has a high flow velocity in the area of the cartridge. Compared with conventional ignition, the solid propellant grains can obtain more quick and uniform ignition and self-sustained combustion by this kind of ablation controlled arc (ACA) plasma via energy skin effect of propellant grains, pre-heat temperature mechanism and high efficient jet diffusion.

  12. Mechanism of plasma ignition in electrothermal-chemical launcher

    Directory of Open Access Journals (Sweden)

    Yong Jin

    2016-04-01

    Full Text Available Plasma generator is a core component in an electrothermal-chemical (ETC launcher. Its work state directly influences the launch efficiency of a system. The interaction between plasma and propellants is a very important mechanism in ETC technology. Based on the transient radiation model and open air plasma jet experiment, the mechanism of plasma ignition process is analyzed. Results show that the surface temperature of local solid propellant grain can quickly achieve the ignition temperature under the action of early transient plasma radiation. But it needs enough time to maintain the high energy flow to make self-sustained combustion of solid propellant grains. Because of the limited space characteristics of transient radiation, the near-field propellant grains can gain enough energy by the strong transient radiation to be ignited and achieve self-sustained combustion. The far-field propellant grains mainly gain the energy by the activated particles in plasma jet to be ignited and self-sustained combustion. Experiments show that plasma jet always has a high flow velocity in the area of the cartridge. Compared with conventional ignition, the solid propellant grains can obtain more quick and uniform ignition and self-sustained combustion by this kind of ablation controlled arc (ACA plasma via energy skin effect of propellant grains, pre-heat temperature mechanism and high efficient jet diffusion.

  13. Stress-induced light scattering method for the detection of latent flaws on fine polished glass substrates

    Science.gov (United States)

    Sakata, Y.; Sakai, K.; Nonaka, K.

    2014-08-01

    Fine polishing techniques, such as the chemical mechanical polishing treatment, are one of the most important technique to glass substrate manufacturing. Mechanical interaction in the form of friction occurs between the abrasive and the substrate surface during polishing, which may cause formation of latent flaws on the glass substrate surface. Fine polishing-induced latent flaws may become obvious during a subsequent cleaning process if glass surfaces are corroded away by chemical interaction with the cleaning liquid. Latent flaws thus reduce product yield. In general, non-destructive inspection techniques, such as the light-scattering methods, used to detect foreign matters on the glass substrate surface. However, it is difficult to detect latent flaws by these methods because the flaws remain closed. Authors propose a novel inspection technique for fine polishing-induced latent flaws by combining the light scattering method with stress effects, referred to as the stress-induced light scattering method (SILSM). SILSM is able to distinguish between latent flaws and particles on the surface. In this method, samples are deformed by an actuator and stress effects are induced around the tips of latent flaws. Due to the photoelastic effect, the refractive index of the material around the tip of a latent flaw is changed. This changed refractive index is in turn detected by a cooled charge-coupled device camera as variations in light scattering intensity. In this report, surface latent flaws are detected non-destructively by applying SILSM to glass substrates, and the utility of SILSM evaluated as a novel inspection technique.

  14. Mechanism-based bioanalysis and biomarkers for hepatic chemical stress.

    Science.gov (United States)

    Antoine, D J; Mercer, A E; Williams, D P; Park, B K

    2009-08-01

    Adverse drug reactions, in particular drug-induced hepatotoxicity, represent a major challenge for clinicians and an impediment to safe drug development. Novel blood or urinary biomarkers of chemically-induced hepatic stress also hold great potential to provide information about pathways leading to cell death within tissues. The earlier pre-clinical identification of potential hepatotoxins and non-invasive diagnosis of susceptible patients, prior to overt liver disease is an important goal. Moreover, the identification, validation and qualification of biomarkers that have in vitro, in vivo and clinical transferability can assist bridging studies and accelerate the pace of drug development. Drug-induced chemical stress is a multi-factorial process, the kinetics of the interaction between the hepatotoxin and the cellular macromolecules are crucially important as different biomarkers will appear over time. The sensitivity of the bioanalytical techniques used to detect biological and chemical biomarkers underpins the usefulness of the marker in question. An integrated analysis of the biochemical, molecular and cellular events provides an understanding of biological (host) factors which ultimately determine the balance between xenobiotic detoxification, adaptation and liver injury. The aim of this review is to summarise the potential of novel mechanism-based biomarkers of hepatic stress which provide information to connect the intracellular events (drug metabolism, organelle, cell and whole organ) ultimately leading to tissue damage (apoptosis, necrosis and inflammation). These biomarkers can provide both the means to inform the pharmacologist and chemist with respect to safe drug design, and provide clinicians with valuable tools for patient monitoring. PMID:19621999

  15. Chemical degradation mechanisms of membranes for alkaline membrane fuel cells

    International Nuclear Information System (INIS)

    Chemical degradation mechanisms of membranes for alkaline membrane fuel cells have been investigated using density functional theory (DFT). We have elucidated that the aryl-ether moiety of membranes is one of the weakest site against attack of hydroxide ions. The results of DFT calculations for hydroxide initiated aryl-ether cleavage indicated that the aryl-ether cleavage occurred prior to degradation of cationic functional group. Such a weak nature of the aryl-ether group arises from the electron deficiency of the aryl group as well as the low bond dissociation energy. The DFT results suggests that removal of the aryl-ether group in the membrane should enhance the stability of membranes under alkaline conditions. In fact, an ether fee poly(phenylene) membrane exhibits excellent stability against the attack from hydroxide ions

  16. Chemical degradation mechanisms of membranes for alkaline membrane fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Choe, Yoong-Kee [National Institute of Advanced Industrial Science and Technology, Umezono 1-1-1, Tsukuba (Japan); Henson, Neil J.; Kim, Yu Seung [Los Alamos National Laboratory, Los Alamos, NM (United States)

    2015-12-31

    Chemical degradation mechanisms of membranes for alkaline membrane fuel cells have been investigated using density functional theory (DFT). We have elucidated that the aryl-ether moiety of membranes is one of the weakest site against attack of hydroxide ions. The results of DFT calculations for hydroxide initiated aryl-ether cleavage indicated that the aryl-ether cleavage occurred prior to degradation of cationic functional group. Such a weak nature of the aryl-ether group arises from the electron deficiency of the aryl group as well as the low bond dissociation energy. The DFT results suggests that removal of the aryl-ether group in the membrane should enhance the stability of membranes under alkaline conditions. In fact, an ether fee poly(phenylene) membrane exhibits excellent stability against the attack from hydroxide ions.

  17. Chemical and Mechanical processes during burial diagenesis of chalk

    DEFF Research Database (Denmark)

    Borre, Mai Kirstine; Lind, Ida

    1998-01-01

    or larger influence on the textural development. In the chalk interval below, compaction is not the only porosity reducing agent but it has a larger influence on texture than concurrent recrystallization. Below 850 m grain-bridging cementation becomes important resulting in a lithified limestone below 1100......Burial diagenesis of chalk is a combination of mechanical compaction and chemical recrystallization as well as cementation. We have predicted the characteristic trends in specific surface resulting from these processes. The specific surface is normally measured by nitrogen adsorption but is here...... in the Pacific, where a > 1 km thick package of chalk facies sediments accumulated from the Cretaceous to the present. In the upper 200-300 m the sediment is unconsolidated carbonate ooze, throughout this depth interval compaction is the principal porosity reducing agent, but recrystallization has an equal...

  18. Mechanism of Interaction between Ionizing Radiation and Chemicals

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Jin Kyu; Lee, B. H.; Shin, H. S. (and others)

    2008-03-15

    This research project has been carried out jointly with INP (Poland) to develop technologies for 'Mechanism of Interaction between ionizing radiation and chemicals{sup .} Several biological end-points were assessed in experimental organisms such as higher plants, rats, cell lines and yeast cells to establish proper bioassay techniques. The Tradescantia somatic cell mutation assay was carried out, and immunohistochemistry and hormone assays were done in Fisher 344 rats and cell lines to analyse the combined effect of ionizing radiation with mercury chloride. Using the common regularities of combined actions of two factors, a theoretical model was established, and applied to the thermo radiation action and synergism between two chemicals, as well. The model approach made it possible to predict the condition under which the maximum synergism could be attained. The research results were published in high standard journals and presented in the scientific conferences to verify KAERI's current technology level. The experience of collaboration can be used as a fundamental tool for multinational collaboration, and make the role of improving relationship between Korea and Poland.

  19. Mechanism of Interaction between Ionizing Radiation and Chemicals

    International Nuclear Information System (INIS)

    This research project has been carried out jointly with INP (Poland) to develop technologies for 'Mechanism of Interaction between ionizing radiation and chemicals. Several biological end-points were assessed in experimental organisms such as higher plants, rats, cell lines and yeast cells to establish proper bioassay techniques. The Tradescantia somatic cell mutation assay was carried out, and immunohistochemistry and hormone assays were done in Fisher 344 rats and cell lines to analyse the combined effect of ionizing radiation with mercury chloride. Using the common regularities of combined actions of two factors, a theoretical model was established, and applied to the thermo radiation action and synergism between two chemicals, as well. The model approach made it possible to predict the condition under which the maximum synergism could be attained. The research results were published in high standard journals and presented in the scientific conferences to verify KAERI's current technology level. The experience of collaboration can be used as a fundamental tool for multinational collaboration, and make the role of improving relationship between Korea and Poland

  20. Subjective Quality of Life of Polish, Polish-Immigrant, and Polish-American Elderly.

    Science.gov (United States)

    Berdes, Celia; Zych, Adam A.

    2000-01-01

    Compares subjective quality of life of elderly Poles living in Poland, and Polish immigrants and Polish-American ethnics living in Chicago as part of a secondary data analysis of a study initially conducted in Poland. Conclusions lend support to the idea that U.S.-born elderly people and elderly immigrants to the United States have a significantly…

  1. Temperature buffer test. Hydro-mechanical and chemical/ mineralogical characterizations

    Energy Technology Data Exchange (ETDEWEB)

    Aakesson, Mattias; Olsson, Siv; Dueck, Ann; Nilsson, Ulf; Karnland, Ola [Clay Technology AB, Lund (Sweden); Kiviranta, Leena; Kumpulainen, Sirpa [BandTech Oy, Helsinki (Finland); Linden, Johan [Aabo Akademi, Aabo (Finland)

    2012-01-15

    The Temperature Buffer Test (TBT) is a joint project between SKB/ANDRA and supported by ENRESA (modeling) and DBE (instrumentation), which aims at improving the understanding and to model the thermo-hydro-mechanical behavior of buffers made of swelling clay submitted to high temperatures (over 100 deg C) during the water saturation process. The test has been carried out in a KBS-3 deposition hole at Aspo HRL. It was installed during the spring of 2003. Two steel heaters (3 m long, 0.6 m diameter) and two buffer arrangements have been investigated: the lower heater was surrounded by rings of compacted Wyoming bentonite only, whereas the upper heater was surrounded by a composite barrier, with a sand shield between the heater and the bentonite. The test was dismantled and sampled during the winter of 2009/2010. This report presents the hydro-mechanical and chemical/mineralogical characterization program which was launched subsequent to the dismantling operation. The main goal has been to investigate if any significant differences could be observed between material from the field experiment and the reference material. The field samples were mainly taken from Ring 4 (located at the mid-section around the lower heater), in which the temperature in the innermost part reached 155 deg C. The following hydro-mechanical properties have been determined for the material (test technique within brackets): hydraulic conductivity (swelling pressure device), swelling pressure (swelling pressure device), unconfined compression strength (mechanical press), shear strength (triaxial cell) and retention properties (jar method). The following chemical/mineralogical properties (methods within brackets) were determined: anion analysis of water leachates (IC), chemical composition (ICP/AES+MS, EGA), cation exchange capacity (CEC, Cu-trien method) and exchangeable cations (exchange with NH4, ICPAES), mineralogical composition (XRD and FTIR), element distribution and microstructure (SEM and

  2. Molecular mechanisms of Tetranychus urticae chemical adaptation in hop fields.

    Science.gov (United States)

    Piraneo, Tara G; Bull, Jon; Morales, Mariany A; Lavine, Laura C; Walsh, Douglas B; Zhu, Fang

    2015-01-01

    The two-spotted spider mite, Tetranychus urticae Koch is a major pest that feeds on >1,100 plant species. Many perennial crops including hop (Humulus lupulus) are routinely plagued by T. urticae infestations. Hop is a specialty crop in Pacific Northwest states, where 99% of all U.S. hops are produced. To suppress T. urticae, growers often apply various acaricides. Unfortunately T. urticae has been documented to quickly develop resistance to these acaricides which directly cause control failures. Here, we investigated resistance ratios and distribution of multiple resistance-associated mutations in field collected T. urticae samples compared with a susceptible population. Our research revealed that a mutation in the cytochrome b gene (G126S) in 35% tested T. urticae populations and a mutation in the voltage-gated sodium channel gene (F1538I) in 66.7% populations may contribute resistance to bifenazate and bifenthrin, respectively. No mutations were detected in Glutamate-gated chloride channel subunits tested, suggesting target site insensitivity may not be important in our hop T. urticae resistance to abamectin. However, P450-mediated detoxification was observed and is a putative mechanism for abamectin resistance. Molecular mechanisms of T. urticae chemical adaptation in hopyards is imperative new information that will help growers develop effective and sustainable management strategies. PMID:26621458

  3. Influence of Polish Climate Conditions on Content and the Chemical Variation of Volatiles in the Roots of Six Eleutherococcus Species and Their Potential Use

    Directory of Open Access Journals (Sweden)

    Daniel Załuski

    2015-08-01

    Full Text Available The aim of this study was the term of the climate influence on essential oil and aroma components of six Eleutherococcus species [E. senticosus (Rupr. & Maxim. Maxim., E. setchuensis (Harms Nakai, E. sessiliflorus (Rupr. & Maxim. S. Y. Hu, E. gracilistylus (W. W. Smith S. Y. Hu, E. henryi Oliv., E. divaricatus (Siebold & Zucc. S. Y. Hu ] cultivated in Poland. The hydrodistilled volatiles of the samples were ranged from 0.2% to 0.4%. The components of the determined volatiles were analyzed by GC/MS/MS. Thirty of the same compounds were present in all samples. Major components of the samples were (E,E-farnesol (43.6-6.9%, (E,Z-farnesol (7.2-0.7%, (Z,E-farnesol (1.4-0.1%, tetradecanoic acid (9.91-2.08%, and pentadecanoic acid (12.8-3.5%. Highest (E,E-farnesol content (43.6% was determined in the roots of E. divaricatus. This compound may be considered as chemical marker of the species. This is the first time, when the analysis of volatiles in the roots of Eleutherococcus spp. cultivated in Poland was performed. This study provides a platform for further investigation for the isolation and pharmacological activity of active principles.

  4. [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

  5. Chemically- and mechanically-mediated influences on the transport and mechanical characteristics of rock fractures

    Energy Technology Data Exchange (ETDEWEB)

    Min, K.-B.; Rutqvist, J.; Elsworth, D.

    2009-02-01

    A model is presented to represent changes in the mechanical and transport characteristics of fractured rock that result from coupled mechanical and chemical effects. The specific influence is the elevation of dissolution rates on contacting asperities, which results in a stress- and temperature-dependent permanent closure. A model representing this pressure-dissolution-like behavior is adapted to define the threshold and resulting response in terms of fundamental thermodynamic properties of a contacting fracture. These relations are incorporated in a stress-stiffening model of fracture closure to define the stress- and temperature-dependency of aperture loss and behavior during stress and temperature cycling. These models compare well with laboratory and field experiments, representing both decoupled isobaric and isothermal responses. The model was applied to explore the impact of these responses on heated structures in rock. The result showed a reduction in ultimate induced stresses over the case where chemical effects were not incorporated, with permanent reduction in final stresses after cooling to ambient conditions. Similarly, permeabilities may be lower than they were in the case where chemical effects were not considered, with a net reduction apparent even after cooling to ambient temperature. These heretofore-neglected effects may have a correspondingly significant impact on the performance of heated structures in rock, such as repositories for the containment of radioactive wastes.

  6. 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.

  7. 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. PMID:20665091

  8. Fused-Polished Fiber Couplers

    Institute of Scientific and Technical Information of China (English)

    Sien; Chi; Shiao-Min; Tseng

    2003-01-01

    We report on fused-polished fiber couplers with a new fabrication method. This structure so fabricated is promising while achieving high-performance all-fiber WDM devices. Potential advantages and prospects of our works are presented.

  9. Co - pyrolysis of biomass and Polish lignite

    Energy Technology Data Exchange (ETDEWEB)

    Kordylewski, Wlodzimierz; Stojanowska, Grazyna [Politechnika Wroclawska, Wroclaw (Poland); Jones, Jenny [Univ. of Leeds (United Kingdom). Energy and Resources Research Inst.

    2006-01-15

    The paper presents results of studies of the chemical decomposition of coal, biomass and their blends during low rate heating gasification in atmosphere of air or nitrogen. Polish lignite (Turow), sawdust of pine and blends of these two fuels have been used in the research and it has been investigated the influence of ion exchanged calcium on their pyrolysis. The primary products of devolatilization provided important information for understanding subsequently the leading to toxic organic compounds and synergistic effects of these fuels. The influence of blending ratio and influence of calcium catalysts was discussed.

  10. Mechanisms and chemical induction of aneuploidy in rodent germ cells

    Energy Technology Data Exchange (ETDEWEB)

    Mailhes, J B; Marchetti, F

    2004-10-15

    The objective of this review is to suggest that the advances being made in our understanding of the molecular events surrounding chromosome segregation in non-mammalian and somatic cell models be considered when designing experiments for studying aneuploidy in mammalian germ cells. Accurate chromosome segregation requires the temporal control and unique interactions among a vast array of proteins and cellular organelles. Abnormal function and temporal disarray among these, and others to be inidentified, biochemical reactions and cellular organelles have the potential for predisposing cells to aneuploidy. Although numerous studies have demonstrated that certain chemicals (mainly those that alter microtubule function) can induce aneuploidy in mammalian germ cells, it seems relevant to point out that such data can be influenced by gender, meiotic stage, and time of cell-fixation post-treatment. Additionally, a consensus has not been reached regarding which of several germ cell aneuploidy assays most accurately reflects the human condition. More recent studies have shown that certain kinase, phosphatase, proteasome, and topoisomerase inhibitors can also induce aneuploidy in rodent germ cells. We suggest that molecular approaches be prudently incorporated into mammalian germ cell aneuploidy research in order to eventually understand the causes and mechanisms of human aneuploidy. Such an enormous undertaking would benefit from collaboration among scientists representing several disciplines.

  11. Performance of a hybrid chemical/mechanical heat pump

    Science.gov (United States)

    Silvestri, John J.; Scaringe, Robert P.; Grzyll, Lawrence R.

    1990-01-01

    The authors present the design and preliminary results of the performance of a hybrid chemical/mechanical, low-lift (20 C) heat pump. Studies have indicated that this heat pump has several advantages over the traditional single fluid vapor compression (reverse Rankine) heat pump. Included in these benefits are: 1) increased COPc due to the approximation of the cycle to the Lorenz cycle and due to the availability of the heat of solution, along with the heat of vaporization, to provide cooling; and 2) ease of variation in system cooling capacity by changing the fluid composition. The system performance is predicted for a variety of refrigerant-absorbent pairs. Cooling capacity is determined for systems operating with ammonia as the refrigerant and lithium nitrate and sodium thiocyanate as the absorbents and also with water as the refrigerant and magnesium chloride, potassium hydroxide, lithium bromide, sodium hydroxide, and sulfuric acid as the absorbents. Early indications have shown that the systems operating with water as the refrigerant operate at 2-4 times the capacity of the ammonia-refrigerant-based systems. Using existing working fluids in the proposed innovative design, a coefficient-of-performance improvement of 21 percent is possible when compared to the best vapor compression systems analyzed.

  12. The Mechanism of Surface Chemical Kinetics of Dissolution of Minerals

    Institute of Scientific and Technical Information of China (English)

    谭凯旋; 张哲儒; 等

    1996-01-01

    This paper deals with the mechanism of dissolution reaction kinetics of minerals in aqueous solution based on the theory of surface chemistry.Surface chemical catalysis would lead to an obvous decrease in active energy of dissolution reaction of minerals.The dissolution rate of minerals is controlled by suface adsorption,surface exchange reaction and desorption,depending on pH of the solution and is directly proportional to δHn0+,When controlled by surface adsorption,i.e.,nθ=1,the dissolution rate will decrease with increasing pH;when controlled by surface exchane reaction,i.e.,nθ=0,the dissolution rate is independent of pH;when controlled by desorption,nθis a positive decimal between 0 and 1 in acidic solution and a negative decimal between-1 and 0 in alkaline solution.Dissolution of many minerals is controlled by surface adsorption and/or surface exchange reactions under acid conditions and by desorption under alkaline conditions.

  13. Endocrine-Disrupting Chemicals: Associated Disorders and Mechanisms of Action

    Directory of Open Access Journals (Sweden)

    Sam De Coster

    2012-01-01

    Full Text Available The incidence and/or prevalence of health problems associated with endocrine-disruption have increased. Many chemicals have endocrine-disrupting properties, including bisphenol A, some organochlorines, polybrominated flame retardants, perfluorinated substances, alkylphenols, phthalates, pesticides, polycyclic aromatic hydrocarbons, alkylphenols, solvents, and some household products including some cleaning products, air fresheners, hair dyes, cosmetics, and sunscreens. Even some metals were shown to have endocrine-disrupting properties. Many observations suggesting that endocrine disruptors do contribute to cancer, diabetes, obesity, the metabolic syndrome, and infertility are listed in this paper. An overview is presented of mechanisms contributing to endocrine disruption. Endocrine disruptors can act through classical nuclear receptors, but also through estrogen-related receptors, membrane-bound estrogen-receptors, and interaction with targets in the cytosol resulting in activation of the Src/Ras/Erk pathway or modulation of nitric oxide. In addition, changes in metabolism of endogenous hormones, cross-talk between genomic and nongenomic pathways, cross talk with estrogen receptors after binding on other receptors, interference with feedback regulation and neuroendocrine cells, changes in DNA methylation or histone modifications, and genomic instability by interference with the spindle figure can play a role. Also it was found that effects of receptor activation can differ in function of the ligand.

  14. Road polishing assessment methodology 'TROWS'

    OpenAIRE

    Gothie, Michel; Do, Minh Tan

    2003-01-01

    Both tire wear and road polishing are complex phenomenon, which are obviously strongly related; the energy that polishes the road is the energy that wears the tire. They both depend non-linearly on numerous parameters, like materials used, vehicle and road usage, environmental conditions (e.g., temperature) and many others. Due to their many economic and ecological implications, including those concerning the road users safety, the possibility to predict them is of major importance to tire ma...

  15. Balanced Unemployment in Polish Economy

    OpenAIRE

    Kamila Szymańska

    2009-01-01

    The article deals with the problem of balanced unemployment in relation to the Polish economy. This issue with its variety considerations and economic, social and political implications is today one of the most important matter. Author analyses this problem together with its reasons and refer it to the Polish economy. In first and second part of the text there are presented basic assumptions of natural unemployment theory and Non-Accelerating Inflation Rate of Unemployment. Third part is an a...

  16. Effect of electrochemical polishing time on surface topography of mild steel

    Institute of Scientific and Technical Information of China (English)

    Baocheng Wang; Jinhua Zhu

    2007-01-01

    The variation in altitude density function (ADF) of the surface topography of mild steel during electrochemical polishing (ECP) was investigated, and the mechanism of the variation of surface roughness with polishing time was analyzed. The results show that the variation trend of ADF with polishing time is flat-steep-flat; the variation of surface roughness results in the different distributions of surface current density, and there is a fine surface smoothness in the special period of ECP from 4 to 8 s.

  17. MECHANIZM OF ANODE DISSOLVING OF CORROSION-RESISTING AND STRUCTURAL CARBON STEELS UNDER ELECTROPULSE POLISHING

    Directory of Open Access Journals (Sweden)

    I. Yunkovsky

    2013-01-01

    Full Text Available In this article were suggested the schemes of anode processes, taking into account the nature of metals, anion structure, pH solution of electrolyte and anode potential by electropulse polishing of corrosion- resisting and structural carbon steels.It is shown and experimentally confirmed, that under conditions of electropulse polishing of anode dissolving of metals, which are contained into corrosion-resisting and structural carbon steels, carried out according to mechanism of complex formation through a set of series and series-parallel of intermediate stages. In the 1st stage on the surface of metals adsorption complexes with participation of chemisorption molecules of water are formed. In the next stages anions of electrolyte’s solution and molecules of water take part. In final stage of dissolving on the surface of anode soluble compounds are formed, which by transition into solution into simple ions are dissociated. It is determined that by electrical-impulse polishing in dissolving of components of corrosion-resisting carbon steels the important role play chemical processes, and anode dissolving of metals take place in the field of mixed electrochemical and diffusion kinetics . Diffusion limitations appear as a result of difficult ion mass transfer through surface salt, oxide and hydro-oxide and absorption-phase coatings.

  18. The impact of 90 years of drainage works on some chemical properties of raised peat bog organic soils - case study from valley of the Upper San river in Polish Bieszczady Mts. (Eastern Carpathians).

    Science.gov (United States)

    Stolarczyk, Mateusz

    2016-04-01

    Wetland ecosystems, including raised peat bogs are characterized by a specific water conditions and unique vegetation, which makes peatland highly important habitats due to protection of biodiversity. Transformation of peat bog areas is particularly related to changes in the environment e.g. according to reclamation works. Drainage of peatlands is directly associated to the decrease of groundwater levels and lead to a number of changes in the chemical and physical properties of peat material, included contents of exchangeable cations in the surface layers of peat soils in the decession phase of peat development and release above compounds from the soil to ground or surface waters. The aim of the research was to determine the impact of extended drainage works on chemical composition of sorption complex of raised peat bog organic soils and identification the potential environmental effects of alkaline cations leaching to the surface waters. Research was carried out on the peat bogs located in the Upper San valley in Polish Bieszczady Mts. (Eastern Carpathians). Soil samples used in this study were collected from 3 soil profiles in 10 or 20 cm intervals to the approximately 130 cm depth. Laboratory analyses included determination of basic properties of organic material such as the degree of peat decomposition, ash content, soil pH and carbon, hydrogen, nitrogen concentrations. Additionally the amount of alkaline cations, exchangeable and extractable acidity was determined. Furthermore, the degree of saturation of the sorption complex with alkaline cations (V) and cation exchange capacity (CEC) are calculated. In order to evaluate the impact of the examined peat bog to the environment, also water samples were collected and ions composition was measured. The obtained results show that studied organic soils are oligotrophic and strongly acidic. In the case of organic material related to decession phase of peat development, as a result of the lengthy drainage works

  19. Chemical and mechanical interactions of interstitials with vanadium alloys

    Energy Technology Data Exchange (ETDEWEB)

    DiStefano, J.R.; Chitwood, L.D.; DeVan, J.H. [Oak Ridge National Laboratory, TN (United States)

    1996-04-01

    Oxidation studies of V-4Cr-4Ti were conducted in air and reduced oxygen partial pressures (10{sup 4}, 10{sup -5} and 10{sup -6} torr). Reaction rates were determined by weight change measurements and chemical analyses. Mechanical properties after the exposures were determined by room temperature tensile tests. In air at 400 and 500{degrees}C, oxide films form on the surface. Initially, rates are high but decrease with time reaching similiar values to those found in oxygen partial pressures at 10{sup -4}, 10{sup -5}, and 10{sup -6} torr. At 400{degrees}C, oxygen pick-up followed a logarithmic function of time and was confined to regions near the surface. Little change in room temperature tensile properties was noted for oxygen increase up to 1500 ppm. Thermal cycling specimens from 400{degrees}C to room temperature up to 14 times had no apparent effect on oxidation rate or tensile properties. At 500{degrees}C, oxygen pick-up appeared to follow a parabolic relation with time. Rates were {approx} 10 times those at 400{degrees}C and correspondingly larger oxygen increases occurred when compared with the 400{degrees}C tests after similiar time periods. This resulted in a significant decrease in total elongation after 240 h. At reduced oxygen partial pressures, rates were measured for times <100 h. Data are relatively sparse but generally show a slightly higher initial rate before slowing. At 400{degrees}C increases to {approx}200 ppm oxygen were found with no effect on room temperature elongation. At 500{degrees}C increase in oxygen of 2400 ppm after 50h/10{sup -5} torr resulted in a decrease of around 25% in room temperature elongation. By comparison, exposure to air at 500{degrees}C for 12 h caused nearly the same results.

  20. An ionic-chemical-mechanical model for muscle contraction.

    Science.gov (United States)

    Manning, Gerald S

    2016-12-01

    The dynamic process underlying muscle contraction is the parallel sliding of thin actin filaments along an immobile thick myosin fiber powered by oar-like movements of protruding myosin cross bridges (myosin heads). The free energy for functioning of the myosin nanomotor comes from the hydrolysis of ATP bound to the myosin heads. The unit step of translational movement is based on a mechanical-chemical cycle involving ATP binding to myosin, hydrolysis of the bound ATP with ultimate release of the hydrolysis products, stress-generating conformational changes in the myosin cross bridge, and relief of built-up stress in the myosin power stroke. The cycle is regulated by a transition between weak and strong actin-myosin binding affinities. The dissociation of the weakly bound complex by addition of salt indicates the electrostatic basis for the weak affinity, while structural studies demonstrate that electrostatic interactions among negatively charged amino acid residues of actin and positively charged residues of myosin are involved in the strong binding interface. We therefore conjecture that intermediate states of increasing actin-myosin engagement during the weak-to-strong binding transition also involve electrostatic interactions. Methods of polymer solution physics have shown that the thin actin filament can be regarded in some of its aspects as a net negatively charged polyelectrolyte. Here we employ polyelectrolyte theory to suggest how actin-myosin electrostatic interactions might be of significance in the intermediate stages of binding, ensuring an engaged power stroke of the myosin motor that transmits force to the actin filament, and preventing the motor from getting stuck in a metastable pre-power stroke state. We provide electrostatic force estimates that are in the pN range known to operate in the cycle. PMID:27603027

  1. 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

  2. Chemical Sensory Mechanisms of Insects%昆虫的化学感觉机理

    Institute of Scientific and Technical Information of China (English)

    娄永根; 程家安

    2001-01-01

    Insects possess two kinds of chemical sensory organ,olfactoryorgan and gustatory organ,by which they can perceive chemical cues in the circumstance and subsequently make a series of corresponding behavioral responses.From perceiving chemical cues to making behavioral responses,it involves in information coding,proceeding and integration to chemical cues at various level in insect nerve system.New pest control methods will be developed with the elucidation of insect chemical sensory mechanisms.

  3. Research progress in tribo-electrochemistry and tribo-electrochemical polishing

    Institute of Scientific and Technical Information of China (English)

    ZHAI Wenjie

    2007-01-01

    In this paper, the status quo and recent progress in the research on tribo-electrochemistry in aqueous and non-aqueous media, respectively, are reviewed. Much more attention has been paid to the tribo-electrochemical mechanisms for the control of friction and wear. Based on a summary of the conventional polishing principles of hard and brittle materials, the tribo-electrochemical polishing method is proposed. The results of the preliminary test show that tribo-electrochemical polishing is promising to become a critical technology in the high efficient polishing and planarization of microelectronic materials.

  4. 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.

  5. Laser polishing for topography management of accelerator cavity surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Liang [College of William and Mary, Williamsburg, VA (United States); Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States); Klopf, J. Mike [College of William and Mary, Williamsburg, VA (United States); Reece, Charles E. [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States); Kelley, Michael J. [College of William and Mary, Williamsburg, VA (United States); Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States)

    2015-07-20

    Improved energy efficiency and reduced cost are greatly desired for advanced particle accelerators. Progress toward both can be made by atomically-smoothing the interior surface of the niobium superconducting radiofrequency accelerator cavities at the machine's heart. Laser polishing offers a green alternative to the present aggressive chemical processes. We found parameters suitable for polishing niobium in all surface states expected for cavity production. As a result, careful measurement of the resulting surface chemistry revealed a modest thinning of the surface oxide layer, but no contamination.

  6. Sensing roughness and polish direction

    Science.gov (United States)

    Jakobsen, M. L.; Olesen, A. S.; Larsen, H. E.; Stubager, J.; Hanson, S. G.; Pedersen, T. F.; Pedersen, H. C.

    2016-04-01

    As a part of the work carried out on 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 relatively large numbers 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, but then the object needs 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 introduces 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 complications during the casting process. In this work we present a method for measuring the RMS-values of the surface roughness while simultaneously determining the polishing direction. We are mainly interested in the RMS-values in the range from 0 - 100 nm, which corresponds to the finish categories of A1, A2 and A3. Based on simple intensity measurements we estimates the RMS-value of the surface roughness, and by using a sectioned annual photo-detector to collect the scattered light we can determine the direction of polishing and distinguish light scattered from random structures and light scattered from scratches.

  7. Program Helps To Determine Chemical-Reaction Mechanisms

    Science.gov (United States)

    Bittker, D. A.; Radhakrishnan, K.

    1995-01-01

    General Chemical Kinetics and Sensitivity Analysis (LSENS) computer code developed for use in solving complex, homogeneous, gas-phase, chemical-kinetics problems. Provides for efficient and accurate chemical-kinetics computations and provides for sensitivity analysis for variety of problems, including problems involving honisothermal conditions. Incorporates mathematical models for static system, steady one-dimensional inviscid flow, reaction behind incident shock wave (with boundary-layer correction), and perfectly stirred reactor. Computations of equilibrium properties performed for following assigned states: enthalpy and pressure, temperature and pressure, internal energy and volume, and temperature and volume. Written in FORTRAN 77 with exception of NAMELIST extensions used for input.

  8. New development of atmospheric pressure plasma polishing

    Institute of Scientific and Technical Information of China (English)

    Bo Wang; Jufan Zhang; Shen Dong

    2009-01-01

    Atmospheric pressure plasma polishing (APPP) is a precision machining technology used for manufacturing high quality optical surfaces. The changes of surface modulus and hardness after machining prove the distinct improvement of surface mechanical properties. The demonstrated decrease of surfacc residual stresses testifies the removal of the former deformation layer.And the surface topographies under atomic force microscope (AFM) and scanning electron microscope (SEM) indicate obvious amelioration of the surface status,showing that the 0.926-nm average surface roughness has been achieved.

  9. Chemical protection against ionizing radiation: a survey of possible mechanisms

    International Nuclear Information System (INIS)

    A comparative survey is given of the hypotheses which have been proposed to explain the protecting and sensitizing action of chemical substances towards ionizing radiation such as gamma radiation or x radiation

  10. Electrochemical studies of Copper, Tantalum and Tantalum Nitride surfaces in aqueous solutions for applications in chemical-mechanical and electrochemical-mechanical planarization

    Science.gov (United States)

    Sulyma, Christopher Michael

    This report will investigate fundamental properties of materials involved in integrated circuit (IC) manufacturing. Individual materials (one at a time) are studied in different electrochemical environmental solutions to better understand the kinetics associated with the polishing process. Each system tries to simulate a real CMP environment in order to compare our findings with what is currently used in industry. To accomplish this, a variety of techniques are used. The voltage pulse modulation technique is useful for electrochemical processing of metal and alloy surfaces by utilizing faradaic reactions like electrodeposition and electrodissolution. A theoretical framework is presented in chapter 4 to facilitate quantitative analysis of experimental data (current transients) obtained in this approach. A typical application of this analysis is demonstrated for an experimental system involving electrochemical removal of copper surface layers, a relatively new process for abrasive-free electrochemical mechanical planarization of copper lines used in the fabrication of integrated circuits. Voltage pulse modulated electrodissolution of Cu in the absence of mechanical polishing is activated in an acidic solution of oxalic acid and hydrogen peroxide. The current generated by each applied voltage step shows a sharp spike, followed by a double-exponential decay, and eventually attains the rectangular shape of the potential pulses. For the second system in chapter 5, open-circuit potential measurements, cyclic voltammetry and Fourier transform impedance spectroscopy have been used to study pH dependent surface reactions of Cu and Ta rotating disc electrodes (RDEs) in aqueous solutions of succinic acid (SA, a complexing agent), hydrogen peroxide (an oxidizer), and ammonium dodecyl sulfate (ADS, a corrosion inhibitor for Cu). The surface chemistries of these systems are relevant for the development of a single-slurry approach to chemical mechanical planarization (CMP) of Cu

  11. Inspection technique of latent flaws on fine polished glass substrates using stress-induced light scattering method

    Science.gov (United States)

    Sakata, Yoshitaro; Sakai, Kazufumi; Nonaka, Kazuhiro

    2014-05-01

    The fine polishing technique, e.g. Chemical Mechanical Polishing treatment (CMP), is one of the most important techniques in the glass substrate manufacturing. However, mechanical interaction, e.g. friction, occurs between the abrasive and the surface of substrates. Therefore, latent flaws are formed in the surfaces of glass substrates depending on the polishing condition. In the case of the cleaning process of the glass substrate in which the latent flaws existed, latent flaws become obvious because glass surfaces were eaten away by chemical interaction of cleaning liquid. Therefore, latent flaws are the cause of decrease the yield of products. In general, non-destructive inspection techniques, e.g. light scattering method, foreign matter on the surface of glass substrates. Though, it is difficult to detect the latent flaws by these method, because these are closed. The present authors propose a novel inspection technique of latent flaws which occurred by the fine polishing technique, using light scattering method with stress concentration (Stress-Induced Light scattering Method; SILSM). SILSM is possible to classify and separately detect latent flaws and particles on the surfaces. Samples are deformed by the actuator and stress concentrations are occurred around the tip of latent flaws. By photo-elastic effect, the refractive index of around the tip of latent flaws is changed. And then, changed refractive index is detected by cooled CCD camera as the light scattering intensity. In this report, applying SILSM to glass substrates, latent flaws on the surface of glass substrates are detected non-destructively, and the usefulness of SILSM is evaluated as novel inspection technique of latent flaws.

  12. 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

  13. Tagged ozone mechanism for MOZART-4, CAM-chem and other chemical transport models

    OpenAIRE

    L. K. Emmons; Hess, P. G.; Lamarque, J. -F.; G. G. Pfister

    2012-01-01

    A procedure for tagging ozone produced from NO sources through updates to an existing chemical mechanism is described, and results from its implementation in the Model for Ozone and Related chemical Tracers (MOZART-4), a global chemical transport model, are presented. Artificial tracers are added to the mechanism, thus, not affecting the standard chemistry. The results are linear in the troposphere, i.e., the sum of ozone from individual tagged sources equals the ...

  14. Mechanisms of selectivity loss during tungsten CVD (chemical vapor deposition)

    Energy Technology Data Exchange (ETDEWEB)

    Creighton, J.R.

    1990-01-01

    The tungsten subfluoride mechanism as well as other proposed mechanisms of selectivity loss are reviewed. To further demonstrate the viability of the tungsten subfluoride mechanism, we have extended the measurement of the tungsten subfluoride production rate down to 450{degree}C. We also report results from some preliminary experiments designed to identify the selectivity loss mechanism when elemental silicon is available for reaction. Comments regarding the origins of the insulator effect and selectivity loss for silane reduction are offered. 23 refs., 2 figs.

  15. Experimental Study on the Effects of Alumina Abrasive Particle Behavior in MR Polishing for MEMS Applications

    Directory of Open Access Journals (Sweden)

    Young-Jae Shin

    2008-01-01

    Full Text Available Recently, the magnetorheological (MR polishing process has been examined asa new ultra-precision polishing technology for micro parts in MEMS applications. In theMR polishing process, the magnetic force plays a dominant role. This method uses MRfluids which contains micro abrasives as a polishing media. The objective of the presentresearch is to shed light onto the material removal mechanism under various slurryconditions for polishing and to investigate surface characteristics, including shape analysisand surface roughness measurement, of spots obtained from the MR polishing process usingalumina abrasives. A series of basic experiments were first performed to determine theoptimum polishing conditions for BK7 glass using prepared slurries by changing the processparameters, such as wheel rotating speed and electric current. Using the obtained results,groove polishing was then performed and the results are investigated. Outstanding surfaceroughness of Ra=3.8nm was obtained on the BK7 glass specimen. The present resultshighlight the possibility of applying this polishing method to ultra-precision micro partsproduction, especially in MEMS applications.

  16. Research on a mechanical polishing method for stainless steel electric kettle surface%不锈钢电水壶曲面机械抛光方法研究

    Institute of Scientific and Technical Information of China (English)

    吴昌林; 范青荣; 耿金龙; 金逸

    2011-01-01

    为解决不锈钢电热水壶在手工抛光方式中存在的污染严重、抛光效率低和质量不稳定等问题,成功自主研发了一套电水壶曲面自动化机械抛光系统,该系统采用了多磨具多工位的抛光方法,可夹持三个水壶同时进行抛光,提高了抛光效率.为确保水壶表面抛光质量,规划了螺旋式刀具路径,同时提出了基于示教法的抛光刀位数据生成方法,并利用NURBS曲线拟合的方法对刀具轨迹进行优化.实验结果证明,与手工抛光方式相比较,该方法大大提高了抛光质量和效率.%To resolve the problems of manual polishing for stainless steel electric kettle,such as,serious pollution, low efficiency and unstable quality,an automatic polishing system for stainless steel electric kettle surface was successfully developed.The system adopted the method of multi-abrasive and multi-station, which can polish three kettles in a time and improve the polishing efficiency; making sure of the polishing quality of kettle surface,the spiral tool path was planed,meanwhile a method of data generating for cutter location with teaching method was recommended and a method of optimal path engendered with NURBS curve fitting was used to optimize the tool path.The experimental result proves that this method can produce higher polishing quality and efficiency compared with manual polishing.

  17. 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.

  18. Sensing roughness and polish direction

    DEFF Research Database (Denmark)

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

    2016-01-01

    and A3 (Finishing guide, Bales). Based on simple intensity measurements, we estimate the RMS-value of the surface roughness, and by using a sectioned annually shaped photo-detector to collect the scattered light, we can determine the direction of polishing and distinguish light scattered from random...

  19. Characterization of colloidal silica abrasives with different sizes and their chemical–mechanical polishing performance on 4H-SiC (0 0 0 1)

    Energy Technology Data Exchange (ETDEWEB)

    Shi, Xiaolei [The 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 [The 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; Gu, Zhonghua; Gong, Hua; Zou, Chunli [The 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)

    2014-07-01

    In this paper, a detailed analysis is presented to characterize the performance of colloidal silica abrasives based slurry with different abrasive sizes on CMP of hexagonal 4H-SiC wafer, and indicates that the abrasive size is an important factor to determine the efficiency of CMP and the final planarization quality of wafer surface. The authors also present a detailed hypothesis to describe the material removal mechanism of 4H-SiC by colloidal silica abrasives during CMP process, and design two groups of experiments to demonstrate the rationality of the hypothesis. Furthermore, the authors put forward some suggestions to optimize the CMP efficiency and planarization quality of 4H-SiC wafer.

  20. An Investigation on a Tin Fixed Abrasive Polishing Pad with Phyllotactic Pattern for Polishing Wafer

    Institute of Scientific and Technical Information of China (English)

    吕玉山; 刘电飞; 寇智慧

    2012-01-01

    In order to improve the polishing ability of polishing pads, a kind of polishing pad with the tin fixed abrasive blocks, which are arranged based on the phyllotaxis theory of biology, was designed and fabricated by the use of electroplating technology, and also its polishing ability for JGS-2 wafer was investigated by polishing experiments. The research resuits show that the phyllotactic parameters of the polishing pad influence the arrangement density of the tin fixed abrasive blocks, the polishing pad with phyllotactic pattern is feasibly fabricated by the use of electroplating technology, and the good polishing result can be obtained by using the polishing pad with pbyllotactic pattern to polish a wafer when the diameter D of the tin fixed abrasive block is between Φ. 3 mm and Φ1. 4 mm, and the phyllotactic coefficient k between 1.0 and 1.1, respectively.

  1. (--Pentazocine induces visceral chemical antinociception, but not thermal, mechanical, or somatic chemical antinociception, in μ-opioid receptor knockout mice

    Directory of Open Access Journals (Sweden)

    Satoh Masamichi

    2011-04-01

    Full Text Available Abstract Background (--Pentazocine has been hypothesized to induce analgesia via the κ-opioid (KOP receptor, although the involvement of other opioid receptor subtypes in the effects of pentazocine remains unknown. In this study, we investigated the role of the μ-opioid (MOP receptor in thermal, mechanical, and chemical antinociception induced by (--pentazocine using MOP receptor knockout (MOP-KO mice. Results (--Pentazocine-induced thermal antinociception, assessed by the hot-plate and tail-flick tests, was significantly reduced in heterozygous and abolished in homozygous MOP-KO mice compared with wildtype mice. The results obtained from the (--pentazocine-induced mechanical and somatic chemical antinociception experiments, which used the hind-paw pressure and formalin tests, were similar to the results obtained from the thermal antinociception experiments in these mice. However, (--pentazocine retained its ability to induce significant visceral chemical antinociception, assessed by the writhing test, in homozygous MOP-KO mice, an effect that was completely blocked by pretreatment with nor-binaltorphimine, a KOP receptor antagonist. In vitro binding and cyclic adenosine monophosphate assays showed that (--pentazocine possessed higher affinity for KOP and MOP receptors than for δ-opioid receptors. Conclusions The present study demonstrated the abolition of the thermal, mechanical, and somatic chemical antinociceptive effects of (--pentazocine and retention of the visceral chemical antinociceptive effects of (--pentazocine in MOP-KO mice. These results suggest that the MOP receptor plays a pivotal role in thermal, mechanical, and somatic chemical antinociception induced by (--pentazocine, whereas the KOP receptor is involved in visceral chemical antinociception induced by (--pentazocine.

  2. Research and Development of Chemical Mechanical Planarization for Ge2Sb2Te5%Ge2Sb2Te5的化学机械抛光研究进展

    Institute of Scientific and Technical Information of China (English)

    何敖东; 刘波; 宋志棠; 冯高明; 朱南飞; 任佳栋; 吴关平; 封松林

    2013-01-01

    相变存储器由于具有非易失性、高速度、低功耗等优点被认为最有可能成为下一代存储器的主流产品,Ge2Sb2Te5 (GST)作为一种传统相变材料已经被广泛应用在相变存储器中,而GST的化学机械抛光作为相变存储器生产的关键工艺目前已被采用.本工作综述了有关GST的化学机械抛光技术研究进展,讨论了GST化学机械抛光过程的影响因素,如下压力、转速、抛光垫、磨料、氧化剂、表面活性剂等,并对目前GST的化学机械抛光机理进行了归纳,进一步展望了GST的化学机械抛光技术的发展前景.%Phase change memory (PCM) is considered a major candidate for next-generation memory due to its nonvolatile,fast program access times,low consumable power.So far chalcogenide Ge2Sb2Te5 (GST),as a traditional phase material,has been widely adopted and investigated for PCM application.Recently,chemical mechanical planarization (CMP) of GST as a key technique for confined structure has been applied in the fabrication of PCM.In this paper,research and development of CMP for GST is reviewed firstly and the impact factors of down force,rotation velocity,polishing pads,and the slurry on the GST CMP are discussed.For the mechanical parameter,the removal rate (RR) of GST increases with the increasing of pressure and rotation velocity firstly,and then reaches saturation or slightly decreases.The gentle mechanical parameter is a better choice for GST CMP due to its lower hardness.With regard to polishing pads,GST polished using Politex reg can attain a better surface quality,and almost no residue and scratches can be found,compared with IC1010.The oxidizer of slurry,such as H2O2,(NH4)2S2O8,KMnO4 and FeCl3 have a great influence on the GST performance,the oxidization capacity of each element in GST alloy is different.Among these elements,Ge is preferentially oxidized,but Te is hard oxidized due to their different electronegativity.RR strongly depends on the p

  3. Chemical mechanisms and reaction rates for the initiation of hot corrosion of IN-738

    Science.gov (United States)

    Fryburg, G. C.; Kohl, F. J.; Stearns, C. A.

    1984-01-01

    Sodium-sulfate-induced hot corrosion of preoxidized IN-738 was studied at 975 C with special emphasis placed on the processes occurring during the long induction period. Thermogravimetric tests were run for predetermined periods of time, and then one set of specimens was washed with water. Chemical analysis of the wash solutions yielded information about water soluble metal salts and residual sulfate. A second set of samples was cross sectioned dry and polished in a nonaqueous medium. Element distributions within the oxide scale were obtained from electron microprobe X-ray micrographs. Evolution of SO was monitored throughout the thermogravimetric tests. Kinetic rate studies were performed for several pertinent processes; appropriate rate constants were obtained from the following chemical reactions: Cr2O3 + 2 Na2SO4(1) + 3/2 O2 yields 2 Na2CrO4(1) + 2 SO3(g)n TiO2 + Na2SO4(1) yields Na2O(TiO2)n + SO3(g)n TiO2 + Na2CrO4(1) yields Na2O(TiO2)n + CrO3(g).

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

    NARCIS (Netherlands)

    Gumuscu, Burcu; Berg, van den 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

  5. Effects of Chairside Polishing and Brushing on Surface Roughness of Acrylic Denture Base Resins

    Institute of Scientific and Technical Information of China (English)

    Seung-Kyun Kim; Ju-Mi Park; Min-Ho Lee; Jae-Youn Jung; Shipu Li; Xinyu Wang

    2009-01-01

    The effects of 3 chairside polishing kits and mechanical brushing on the surface roughness of 3 different acrylic denture base resins were compared. Acrylic denture base resins (auto-polymerizing, heat-polymerizing, injected heat-polymerizing resins) were examined after a tungsten carbide bur, and after chairside polishing using 3 polishing kits and pumice. The specimens were subjected to mechanical brushing using a wear tester to simulate 30 000 strokes of brushing. The surface roughness of the acrylic denture base resin specimens was measured using a contact pro-filometer. After the test, the random polished acrylic resins were evaluated by scanning electron mi-croscopy (SEM) and atomic force microscopy (AFM). Acrylic denture base resins polished using the 3 types of polishing kits had a smoother surface than those finished with the tungsten carbide bur (p <0.05). The surface of the resin polished by a TC cutter exceeded the Ra of 0.2 μm (p<0.05). The auto-polymerizing resin showed a significantly higher surface roughness than the heat-polymerizing resin and injected heat-polymerizing resin (p>0.05). In the case of polishing step wise, there was almost no change in surface roughness after brushing (p>0.05).

  6. Development of Application of RE Polishing Materials

    Institute of Scientific and Technical Information of China (English)

    Li Xueshun; Huang Shaodong; Yang Guosheng

    2004-01-01

    The manufacturing method and functions of the RE polishing powder and comparation of the current situation of its production and application home and abroad were introduced.By analyzing the development of the liquid crystal (plate) display, the wide application of the RE polishing powder in the field of the liquid crystal display and predicts the development direction of the market of the RE polishing powder was presented.In addition, the development trends of the RE polishing powder industry and forecasts the application prospect of the RE polishing powder was analyzed.

  7. Effect of Chemical Corrosion on the Mechanical Characteristics of Parent Rocks for Nuclear Waste Storage

    Directory of Open Access Journals (Sweden)

    Tielin Han

    2016-01-01

    Full Text Available Long-term immersion was adopted to explore the damage deterioration and mechanical properties of granite under different chemical solutions. Here, granite was selected as the candidate of parent rocks for nuclear waste storage. The physical and mechanical properties of variation regularity immersed in various chemical solutions were analyzed. Meanwhile, the damage variable based on the variation in porosity was used in the quantitative analysis of chemical damage deterioration degree. Experimental results show that granite has a significant weakening tendency after chemical corrosion. The fracture toughness KIC, splitting tensile strength, and compressive strength all demonstrate the same deteriorating trend with chemical corrosion time. However, a difference exists in the deterioration degree of the mechanical parameters; that is, the deterioration degree of fracture toughness KIC is the greatest followed by those of splitting tensile strength and compressive strength, which are relatively smaller. Strong acid solutions may aggravate chemical damage deterioration in granite. By contrast, strong alkaline solutions have a certain inhibiting effect on chemical damage deterioration. The chemical solutions that feature various compositions may have different effects on chemical damage degree; that is, SO42- ions have a greater effect on the chemical damage in granite than HCO3- ions.

  8. Evaluation of the surface roughness in dental ceramics submitted to different finishing and polishing methods.

    Science.gov (United States)

    Vieira, Alex C; Oliveira, Mario C S; Lima, Emilena M C X; Rambob, Isabel; Leite, Mariana

    2013-09-01

    Ceramic restorations have been widely used in dentistry. These restorations often require intraoral adjustment with diamond burs after their cementation causing increasing roughness of the ceramic surface. Consequently some finishing and polishing methods have been used to minimize this occurrence. The aim of this study is to evaluate the roughness of the ceramic surfaces submitted to different finishing and polishing methods. 144 specimens of VITAVM(®)7, VM(®)9 and VM(®)13 (VITA Zahnfabrik) ceramics were fabricated and submitted to grinding using diamond burs. They were then divided into 15 groups (five of each ceramic type). Groups 1, 6 and 11-positive control (Glaze); Groups 2, 7 and 12-negative control (no polishing); Groups 3, 8 and 13-polished with abrasive rubbers (Edenta), felt disc and diamond polishing past; Groups 4, 9 and 14-polished with abrasive rubbers (Shofu), felt disc and diamond polishing past; Groups 5, 10 and 15-polished with aluminum oxide discs (Sof-Lex, 3M-ESPE), felt disc and diamond polishing paste. The roughness of the samples surfaces were measured using the rugosimeter Surfcorder SE 1700 and the data were submitted to statistical analysis using ANOVA and Tukey test at a level of significance of 5 %. There was statistically significance difference between the positive control groups and the other groups in all the ceramic types. Mechanical finishing and polishing methods were not able to provide a surface as smooth as the glazed surface for the tested ceramics. To assist dental practitioners to select the best finishing and polishing methods for the final adjustment of the ceramic restorations. PMID:24431749

  9. Mechanical behavior of chemically treated Jute/Polymer composites

    Directory of Open Access Journals (Sweden)

    Murali B

    2014-03-01

    Full Text Available Fiber which serves as a reinforcement in reinforced plastics may be synthetic or natural past studies show that only artificial fibers such as glass, carbon etc., have been used in fiber reinforced plastics. Although glass and other synthetic fiber reinforced plastics possess high specific strength, their fields of application are very limited because of their inherent higher cost of production. In this connection, an investigation has been carried out to make use of jute , a natural fiber abundantly available in India. Natural fibers are not only strong and lightweight but also relatively very cheap. In the present work, jute composites are developed and their mechanical properties are evaluated. Mechanical properties of jute/polymer and compared with glass fiber/epoxy. These results indicate that jute can be used as a potential reinforcing material for making low load bearing thermoplastic composites.

  10. Effect of mechanical stress on biofilms challenged by different chemicals

    OpenAIRE

    Simões, M; Pereira, Maria Olívia; Vieira, M. J.

    2005-01-01

    In this study a methodology was applied in order to ascertain the mechanical stability of biofilms, by using a stainlesssteel (SS) rotating device immersed in a biological reactor where biofilms formed by Pseudomonas fluorescens were allowed to grow for 7 days at a Reynolds number of agitation of 2400. The biofilms developed with this system were characterised in terms of amount of total, extracellular and intracellular proteins and polysaccharides, amount of mass, metabolic activ...

  11. 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.

  12. 2010 University Exemplary Department Award honors chemical engineering, entomology, and mechanical engineering

    OpenAIRE

    Owczarski, Mark

    2010-01-01

    Virginia Tech's Department of Entomology in the College of Agriculture and Life Sciences and the Department of Chemical Engineering and the Department of Mechanical Engineering in the College of Engineering have been recognized with the 2010 University Exemplary Department Award.

  13. Efficacy and mechanisms of non-antibacterial, chemical plaque control by dentifrices - An in vitro study

    NARCIS (Netherlands)

    Busscher, Henk J.; White, Don J.; Atema-Smit, Jelly; van der Mei, Henny C.

    2007-01-01

    Objectives: The provision of antiplaque benefits to dentifrices assists patients in improving hygiene and reducing susceptibility to gingivitis and caries. Chemical plaque control involves different mechanisms and is mostly associated with antibacterial effects, but also includes effects on pellicle

  14. Evidentiality in English and Polish

    OpenAIRE

    Gurajek, Beata

    2010-01-01

    This thesis provides a synchronic account of evidentiality in English and Polish and the main ideas associated with the research on evidentiality with reference to these languages. Chapter 1 provides the review of main ideas as presented in the literature on the topic. Linguists provide varied definitions of evidentiality, therefore chapter 2 gives a unified description of evidentiality, understood as an independent grammatical and semantic category, and offers an organised account of its sem...

  15. Interculutral Polish-Chinese QQing

    OpenAIRE

    Elżbieta Gajek,

    2012-01-01

    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 mod...

  16. Polish technologies on-line

    OpenAIRE

    Dominiak, Maciej (OPI); Lipiec, Krzysztof (OPI); Siwek, Krystyna (OPI); Ossowski, Maciej (OPI); GreyNet, Grey Literature Network Service

    2008-01-01

    In February 2008 the internet service POLSKIETECHNOLOGIE.pl was opened by Information Processing Centre in Warsaw (OPI). The strategic objective was to improve access to technologies offered to the Polish small land medium enterprises by research organizations. The below article presents the portal's principles of working and observations after the first year of its functioning. Includes: Conference preprint, Powerpoint presentation, Abstract and Biographical notes, Pratt student commentar...

  17. THE CHANGING POLISH FOOD CONSUMER

    OpenAIRE

    Sznajder, Michal; Senauer, Benjamin

    1998-01-01

    This paper provides an overview of major demographic and food trends in Poland and the rapid changes in Polish food retailing. The demographic changes include the size of the population; birth, death, marriage and divorce rates; the age distribution, education and household types. Two important demographic factors that will affect food consumption are the aging population and the major gap in education between urban and rural areas. In the next 20 years, the number of children will decrease r...

  18. Chemical kinetic mechanism for the oxidation of paraffinic hydrocarbons needed for primary reference fuels

    Energy Technology Data Exchange (ETDEWEB)

    Westbrook, C.K.; Pitz, W.J.

    1993-03-01

    A detailed chemical kinetic reaction mechanism is described which simulates the oxidation of the primary reference fuels n-heptane and iso-octane. The high temperature subset of these mechanisms is identified, and the extensions to deal with low temperature conditions are also explained. The algorithms used to assign reaction rates to elementary steps in the reaction mechanism are described, and the means of identifying the different chemical species and the relevant reactions are outlined. Finally, we show how interested kinetic modeling researchers can obtain copies of this reaction mechanism.

  19. Chemical and mechanical control of corrosion product transport

    Energy Technology Data Exchange (ETDEWEB)

    Hede Larsen, O.; Blum, R. [I/S Fynsvaerket, Faelleskemikerne, Odense (Denmark); Daucik, K. [I/S Skaerbaekvaerket, Faelleskemikerne, Fredericia (Denmark)

    1996-12-01

    The corrosion products formed in the condensate and feedwater system of once-through boilers are precipitated and deposited inside the evaporator tubes mainly in the burner zone at the highest heat flux. Depositions lead to increased oxidation rate and increased metal temperature of the evaporator tubes, hereby decreasing tube lifetime. This effect is more important in the new high efficiency USC boilers due to increased feedwater temperature and hence higher thermal load on the evaporator tubes. The only way to reduce the load on the evaporator tubes is to minimise corrosion product transport to the boiler. Two general methods for minimising corrosion product transport to the boiler have been evaluated through measurement campaigns for Fe in the water/steam cycle in supercritical boilers within the ELSAM area. One method is to reduce corrosion in the low temperature condensate system by changing conditioning mode from alkaline volatile treatment (AVT) to oxygenated treatment (OT). The other method is to filtrate part of the condensate with a mechanical filter at the deaerator. The results show, that both methods are effective at minimising Fe-transport to the boiler, but changing to OT has the highest effect and should always be used, whenever high purity condensate is maintained. Whether mechanical filtration also is required, depends on the boiler, specifically the load on the evaporator. A simplified calculation model for lifetime evaluation of evaporator tubes has been developed. This model has been used for evaluating the effect of corrosion product transport to the boiler on evaporator tube lifetime. Conventional supercritical boilers generally can achieve sufficient lifetime by AVT and even better by OT, whereas all measures to reduce Fe-content of feedwater, including OT and mechanical filtration, should be taken, to ensure sufficient lifetime for the new boilers with advanced steam data - 290 bar/580 deg. C and above. (au)

  20. Corrosion problems of materials for mechanical, power and chemical engineering

    International Nuclear Information System (INIS)

    The proceedings contain 47 contributions, out of which 8 have been inputted in INIS. These are concerned with various corrosion problems of WWER primary circuit components and their testing. The factors affecting the corrosion resistance are analyzed, the simultaneous corrosion action of decontamination of steels is assessed, and the corrosion cracking of special steels is dealt with. The effects of deformation on the corrosion characteristics are examined for steel to be used in fast reactors. The corrosion potentials were measured for various steels. A testing facility for corrosion-mechanical tests is briefly described. (M.D.). 5 figs., 5 tabs., 25 refs

  1. Electrochemical behavior and polishing properties of silicon wafer in alkaline slurry with abrasive CeO2

    Institute of Scientific and Technical Information of China (English)

    SONG Xiao-lan; XU Da-yu; ZHANG Xiao-wei; SHI Xun-da; JIANG Nan; QIU Guan-zhou

    2008-01-01

    The electrochemical behavior of silicon wafer in alkaline slurry with nano-sized CeO2 abrasive was investigated. The variations of corrosion potential (φcorr) and corrosion current density (Jcorr) of the P-type (100) silicon wafer with the slurry pH value and the concentration of abrasive CeO2 were studied by polarization curve technologies. The dependence of the polishing rate on the pH and the concentration of CeO2 in slurries during chemical mechanical polishing(CMP) were also studied. It is discovered that there is a large change of φcorr and Jcorr when slurry pH is altered and the Jcorr reaches the maximum (1.306 μA/cm2) at pH 10.5 when the material removal rate(MRR) comes to the fastest value. The Jcorr increases gradually from 0.994 μA/cm2 with 1% CeO2 to 1.304 μA/cm2 with 3% CeO2 and reaches a plateau with the further increase of CeO2 concentration. There is a considerable MRR in the slurry with 3% CeO2 at pH 10.5. The coherence between Jcorr and MRR elucidates that the research on the electrochemical behavior of silicon wafers in the alkaline slurry could offer theoretic guidance on silicon polishing rate and ensure to adjust optimal components of slurry.

  2. Parameter Optimization for Laser Polishing of Niobium for SRF Applications

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Liang [Thomas Jefferson National Accelerator Facility, Newport News, VA (United States) and William and Mary College, Williamsburg, VA (United States); Klopf, John Michael [Thomas Jefferson National Accelerator Facility, Newport News, VA (United States); Reece, Charles E. [Thomas Jefferson National Accelerator Facility, Newport News, VA (United States); Kelley, Michael J. [Thomas Jefferson National Accelerator Facility, Newport News, VA (United States) and William and Mary College, Williamsburg, VA (United States)

    2013-06-01

    Surface smoothness is critical to the performance of SRF cavities. As laser technology has been widely applied to metal machining and surface treatment, we are encouraged to use it on niobium as an alternative to the traditional wet polishing process where aggressive chemicals are involved. In this study, we describe progress toward smoothing by optimizing laser parameters on BCP treated niobium surfaces. Results shows that microsmoothing of the surface without ablation is achievable.

  3. Free Energies of Chemical Reactions in Solution and in Enzymes with Ab Initio Quantum Mechanics/Molecular Mechanics Methods

    Science.gov (United States)

    Hu, Hao; Yang, Weitao

    2008-05-01

    Combined quantum mechanics/molecular mechanics (QM/MM) methods provide an accurate and efficient energetic description of complex chemical and biological systems, leading to significant advances in the understanding of chemical reactions in solution and in enzymes. Here we review progress in QM/MM methodology and applications, focusing on ab initio QM-based approaches. Ab initio QM/MM methods capitalize on the accuracy and reliability of the associated quantum-mechanical approaches, however, at a much higher computational cost compared with semiempirical quantum-mechanical approaches. Thus reaction-path and activation free-energy calculations based on ab initio QM/MM methods encounter unique challenges in simulation timescales and phase-space sampling. This review features recent developments overcoming these challenges and enabling accurate free-energy determination for reaction processes in solution and in enzymes, along with applications.

  4. Successful intervention in a child with toxic methemoglobinemia due to nail polish remover poisoning

    Directory of Open Access Journals (Sweden)

    Soumya Patra

    2011-01-01

    Full Text Available Children are most susceptible to accidental exposure of common household substances and one of the common household substances is nail polish remover. We are presenting a case of accidental ingestion of nail polish remover with lethal methemoglobinemia (serum methemoglobin level-72%. This patient was treated successfully with injection methylene blue. However, even small amounts can be dangerous to children, so it is important to keep this and all household chemicals in a safe place

  5. NIR Analysis of Rice Bran Depending on DifferentPercentages of Rice Polishing

    OpenAIRE

    Kumagai, Masanori; Takahashi, Toru; Takahashi, Hitoshi; Ogawa, Nobuaki; TOEDA, Kazuki

    2006-01-01

    Generally, in the case of agricultural products, some difficulties, resulting from the broad peak intensity and extensive overlapping of NIR absorption bands derived from complex chemical components that exist in the sample, arise in relation to specific functionalities of those spectra. This study is intended to specify the NIR spectra of rice bran depending on different percentages of rice polishing. Sample sets were prepared by polishing and grinding away 5% increments of the original mass...

  6. Effects of Hygrothermal Cycling on the Chemical, Thermal, and Mechanical Properties of 862/W Epoxy Resin

    Science.gov (United States)

    Miller, Sandi G.; Roberts, Gary D.; Copa, Christine C.; Bail, Justin L.; Kohlman, Lee W.; Binienda, Wieslaw K.

    2011-01-01

    The hygrothermal aging characteristics of an epoxy resin were characterized over 1 year, which included 908 temperature and humidity cycles. The epoxy resin quickly showed evidence of aging through color change and increased brittleness. The influence of aging on the material s glass transition temperature (Tg) was evaluated by Differential Scanning Calorimetry (DSC) and Dynamic Mechanical Analysis (DMA). The Tg remained relatively constant throughout the year long cyclic aging profile. The chemical composition was monitored by Fourier Transform Infrared Spectroscopy (FTIR) where evidence of chemical aging and advancement of cure was noted. The tensile strength of the resin was tested as it aged. This property was severely affected by the aging process in the form of reduced ductility and embrittlement. Detailed chemical evaluation suggests many aging mechanisms are taking place during exposure to hygrothermal conditions. This paper details the influence of processes such as: advancement of cure, chemical degradation, and physical aging on the chemical and physical properties of the epoxy resin.

  7. Water effect on peroxy radical measurement by chemical amplification: Experimental determination and chemical mechanism

    Institute of Scientific and Technical Information of China (English)

    QI Bin; LIU Lu; CHAO YuTao; WANG ZhuQing; YANG HongYan

    2008-01-01

    The water effect on peroxy radical measurement by chemical amplification was determined experi-mentally for HO2 and HO2+OH, respectively at room temperature (298+9) K and atmospheric pressure (1×105 Pa). No significant difference in water effect was observed with the type of radicals. A theoretical study of the reaction of HO2. H2O adduct with NO was performed using density functional theory at CCSD(T)/6-311 G(2d, 2p)//B3LYPI6-311 G(2d, 2p) level of theory. It was found that the primary reaction channel for the reaction is HO2. H2O+NO→HNO3+H2O (R4a). On the basis of the theoretical study, the rate constant for (R4a) was calculated using Polyrate Version 8.02 program. The fitted Arrenhnius equation for (R4a) is k=5.49×107 T1.03exp(-14798/T) between 200 and 2000 K. A chemical model in-corporated with (R4a) was used to simulate the water effect. The water effect curve obtained by the model is in accordance with that of the experiment, suggesting that the water effect is probably caused mainly by (R4a).

  8. Water effect on peroxy radical measurement by chemical amplification: Experimental determination and chemical mechanism

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The water effect on peroxy radical measurement by chemical amplification was determined experimentally for HO2 and HO2+OH, respectively at room temperature (298±2) K and atmospheric pressure (1×105 Pa). No significant difference in water effect was observed with the type of radicals. A theoretical study of the reaction of HO2·H2O adduct with NO was performed using density functional theory at CCSD(T)/6-311 G(2d, 2p)//B3LYP/6-311 G(2d, 2p) level of theory. It was found that the primary reaction channel for the reaction is HO2·H2O+NO→HNO3+H2O (R4a). On the basis of the theoretical study, the rate constant for (R4a) was calculated using Polyrate Version 8.02 program. The fitted Arrenhnius equation for (R4a) is k = 5.49×107 T 1.03exp(?14798/T) between 200 and 2000 K. A chemical model incorporated with (R4a) was used to simulate the water effect. The water effect curve obtained by the model is in accordance with that of the experiment, suggesting that the water effect is probably caused mainly by (R4a).

  9. An Overview of Polish Martial Arts

    Directory of Open Access Journals (Sweden)

    Wojciech J. Cynarski

    2012-07-01

    Full Text Available The purpose of this study is to explain the revival of Polish martial arts from the perspectives of cultural sociology, the sciences of physical culture, and the humanistic theory of martial arts. The Polish Martial Arts (Polskie Sztuki Walki are a subject still requiring serious scientific examination, even in Poland. There are few works concerning the history of Polish weapons, and most only describe techniques for wielding specific types of edged weapons. Nevertheless, there is a large group of enthusiasts trying to restore and cultivate the old Polish tradition, a tradition with heavy emphasis on the art of fencing. The author knows many of the people and facts presented here, from personal observation and from direct participation in these arts. As a disciple of the late Master Yoshio Sugino (10th-dan Kobudo Katori Shinto-ryu, he fought against the Polish saber champion, and he has taken part in joint exhibitions of Polish and Japanese fencing.

  10. Cellular and molecular mechanisms of chemical synaptic transmission.

    Science.gov (United States)

    Millhorn, D E; Bayliss, D A; Erickson, J T; Gallman, E A; Szymeczek, C L; Czyzyk-Krzeska, M; Dean, J B

    1989-12-01

    During the last decade much progress has been made in understanding the cellular and molecular mechanisms by which nerve cells communicate with each other and nonneural (e.g., muscle) target tissue. This review is intended to provide the reader with an account of this work. We begin with an historical overview of research on cell-to-cell communication and then discuss recent developments that, in some instances, have led to dramatic changes in the concept of synaptic transmission. For instance, the finding that single neurons often contain multiple messengers (i.e., neurotransmitters) invalidated the long-held theory (i.e., Dale's Law) that individual neurons contain and release one and only one type of neurotransmitter. Moreover, the last decade witnessed the inclusion of an entire group of compounds, the neuropeptides, as messenger molecules. Enormous progress has also been made in elucidating postsynaptic receptor complexes and biochemical intermediaries involved in synaptic transmission. Here the development of recombinant DNA technology has made it possible to clone and determine the molecular structure for a number of receptors. This information has been used to gain insight into how these receptors function either as a ligand-gated channel or as a G protein-linked ligand recognition molecule. Perhaps the most progress made during this era was in understanding the molecular linkage of G protein-linked receptors to intramembranous and cytoplasmic macromolecules involved in signal amplification and transduction. We conclude with a brief discussion of how synaptic transmission leads to immediate alterations in the electrical activity and, in some cases, to a change in phenotype by altering gene expression. These alterations in cellular behavior are believed to be mediated by phosphoproteins, the final biochemical product of signal transduction. PMID:2575357

  11. Report of National Cancer Institute symposium: comparison of mechanisms of carcinogenesis by radiation and chemical agents. I. Common molecular mechanisms

    Energy Technology Data Exchange (ETDEWEB)

    Borg, D.C.

    1984-01-01

    Some aspects of molecular mechanisms common to radiation and chemical carcinogenesis are discussed, particularly the DNA damage done by these agents. Emphasis is placed on epidemiological considerations and on dose-response models used in risk assessment to extrapolate from experimental data obtained at high doses to the effects from long-term, low-level exposures. 3 references, 6 figures. (ACR)

  12. Evaluation of Aromatic Oxidation Reactions in Seven Chemical Mechanisms with an Outdoor Chamber

    Science.gov (United States)

    Simulations using seven chemical mechanisms are intercompared against O3, NOx and hydrocarbon data from photooxidation experiments conducted at the University of North Carolina outdoor smog chamber. The mechanisms include CB4–2002, CB05, CB05-TU, a CB05 vari...

  13. Reduced chemical kinetic mechanisms for NOx emission prediction in biomass combustion

    DEFF Research Database (Denmark)

    Houshfar, Ehsan; Skreiberg, Øyvind; Glarborg, Peter;

    2012-01-01

    Because of the complex composition of biomass, the chemical mechanism contains many different species and therefore a large number of reactions. Although biomass gas‐phase combustion is fairly well researched and understood, the proposed mechanisms are still complex and need very long computational...... reactions and chemical species, that is, 35 species and 198 reactions, corresponding to 72% reduction in the number of reactions and, therefore, improving the computational time considerably. Yet, the model based on the reduced mechanism predicts correctly concentrations of NOx and CO that are essentially...... parameters on NOx emission. © 2012 Wiley Periodicals, Inc. Int J Chem Kinet 44: 219–231, 2012...

  14. Polish in the light of grammaticalization theory

    Directory of Open Access Journals (Sweden)

    Björn Hansen

    2015-11-01

    Full Text Available Polish in the light of grammaticalization theory The paper is concerned with grammaticalization, a type of language change whereby lexical items, in specifi contexts, come to serve grammatical functions, and grammatical items acquire new grammatical functions. The aim is twofold: to shed light at the main properties of grammaticalization, and to demonstrate its applicability to Polish data. Some prominent examples in Polish are discussed: the grammaticalization of modals, imperative and avertive constructions. The paper closes with a non-exhaustive list of leads for further research into grammaticalization in Polish.

  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

    ABSTRACT Introduction: Debris buildup on the bracket-wire interface can influence friction. Cleansing brackets with air-powder polishing can affect this process. Objective: 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. Methods: 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 < 0.05. Results: 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 < 0.01). Image analysis showed that the control group exhibited greater debris buildup (median = 2.0) compared with the group that received prophylaxis with air-powder polishing (median = 0.5) (p < 0.05). Conclusion: Cleansing orthodontic brackets with air-powder polishing significantly reduces debris buildup on the bracket surface while decreasing friction levels observed during sliding mechanics. PMID:27653265

  16. Perceptions of and Attitudes towards Regional Varieties of Polish: Views from Two Polish Provinces

    Science.gov (United States)

    Milobog, Magdalena; Garrett, Peter

    2011-01-01

    This paper reports a study of perceptions and attitudes relating to regional varieties of Polish. The methodology followed folk linguistic approaches to attitudes research. Respondents in two Polish provinces were asked to draw on a map of Poland where they thought the main regional varieties of Polish were spoken, and then to name and…

  17. 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.

  18. Response of mechanical properties of glasses to their chemical, thermal and mechanical histories

    DEFF Research Database (Denmark)

    Yue, Yuanzheng

    of glass fibers are dependent on the thermal history (measured as fictive temperature), tension, chemical composition and redox state. However, the fictive temperature affects the hardness of bulk glass in a complicated manner, i.e., the effect does not exhibit a clear regularity in the range...

  19. Material Characterization in the Electro-Analytic Approach for Applications in Chemical Mechanical Planarization and Electrochemical Energy Systems

    Science.gov (United States)

    Rock, Simon E.

    the generation of ion-incorporated tantalum pentoxide. DBSA strongly affects the CMP chemistry of Cu, but exhibits relatively weaker effects on the surface activity of Ta, and thus plays a vital role in dictating the selectivity of Ta:Cu polish rates. CMP of tantalum nitride is also an essential step of material processing in the fabrication of integrated circuits, which is looked separately in this thesis. The present work investigates certain chemical aspects of this strategy of TaN-CMP by also using guanidine carbonate (GC) as a surface complexing agent, and employing electrochemical experiments. The experiments are designed to study the chemical and electrochemical origins of the CMP-specific surface complex films formed on a TaN wafer in acidic solutions of GC and hydrogen peroxide. Open circuit potential, polarization resistance, and electrochemical impedance measurements are employed to probe the surface effects that facilitate material removal in chemically prevailing CMP of TaN. The results are discussed in view of designing slurry variables to support barrier layer planarization with reduced roles of mechanical abrasion. Nonvolatile and nonflammable ionic liquids (ILs) have distinct thermal advantages over the traditional organic solvent electrolytes of lithium ion batteries. However, this beneficial feature of ILs is often counterbalanced by their high viscosity (a limiting factor for ionic conductivity) and, sometimes, by their unsuitable electrochemistry for generating protective layers on electrode surfaces. In an effort to alleviate these limiting Aspects of ILs, we have synthesized a PEGylated imidazolium bis(triflouromethylsulfonyl)amide (bistriflamide) IL that exhibited better thermal and electrochemical stability than a conventional electrolyte based on a blend of ethylene carbonate and diethyl carbonate. The electrochemical performance of this IL has been demonstrated using a cathode consisting of ball-milled LiMn2O4 particles. A direct comparison

  20. Household Chemical Emergencies

    Science.gov (United States)

    ... and disposing of the material according to the manufacturer’s directions. It is critical to store household chemicals in places where children cannot access them. Remember that products such as aerosol cans of hair spray and deodorant, nail polish ...

  1. Stochastic innovation as a mechanism by which catalysts might self-assemble into chemical reaction networks

    OpenAIRE

    Bradford, Justin A; Dill, Ken A.

    2007-01-01

    We develop a computer model for how two different chemical catalysts in solution, A and B, could be driven to form AB complexes, based on the concentration gradients of a substrate or product that they share in common. If A's product is B's substrate, B will be attracted to A, mediated by a common resource that is not otherwise plentiful in the environment. By this simple physicochemical mechanism, chemical reactions could spontaneously associate to become chained together in solution. Accord...

  2. Time-dependent protection of ground and polished Cu using graphene film

    International Nuclear Information System (INIS)

    Highlights: • Graphene was deposited on polished and ground Cu sheets by CVD. • Graphene films provide better protection to polished Cu for short time. • Multilayer graphene films provide better protection for short time. - Abstract: Graphene was deposited on Cu sheets with different morphologies by chemical vapor deposition. Scanning electron microscopy (SEM) analysis indicated that the morphology of the Cu sheet affected the graphene film properties. Electrochemical impedance spectroscopy measurements showed that the graphene film did not effectively protect Cu against corrosion because of prolonged exposure to ionic environments (3.5 wt.% NaCl solution). For short durations, graphene films provided better protection to polished Cu than ground Cu. Prolonged electrolyte immersion of graphene-coated Cu samples showed that the graphene film from the polished Cu surface was detached more easily than that from ground Cu

  3. Organic chemical aging mechanisms: An annotated bibliography. Waste Tank Safety Program

    Energy Technology Data Exchange (ETDEWEB)

    Samuels, W.D.; Camaioni, D.M.; Nelson, D.A.

    1993-09-01

    An annotated bibliography has been compiled of the potential chemical and radiological aging mechanisms of the organic constituents (non-ferrocyanide) that would likely be found in the UST at Hanford. The majority of the work that has been conducted on the aging of organic chemicals used for extraction and processing of nuclear materials has been in conjunction with the acid or PUREX type processes. At Hanford the waste being stored in the UST has been stabilized with caustic. The aging factors that were used in this work were radiolysis, hydrolysis and nitrite/nitrate oxidation. The purpose of this work was two-fold: to determine whether or not research had been or is currently being conducted on the species associated with the Hanford UST waste, either as a mixture or as individual chemicals or chemical functionalities, and to determine what areas of chemical aging need to be addressed by further research.

  4. The Bulgarian-Polish-Russian parallel corpus

    Directory of Open Access Journals (Sweden)

    Maksim Duškin

    2015-11-01

    Full Text Available The Bulgarian-Polish-Russian parallel corpusThe Semantics Laboratory Team of Institute of Slavic Studies of Polish Academy of Sciences is planning to begin work on the creation of a Bulgarian-Polish-Russian parallel corpus. The three selected languages are representatives of the main groups of Slavic languages: Bulgarian represents the southern group of Slavic languages, Polish – the western group of Slavic languages, Russian – the eastern group of Slavic languages. Our project will be the first parallel corpus of these three languages. The planned corpus will be based on material, dating from one period (the 20th century and will have a synchronous nature. The project will not constitute the sum of the separate corpora of selected languages.One of the problems with creating multilingual parallel corpora are different proportions of translated texts between the selected languages, for example, Polish literature is often translated into Bulgarian, but not vice versa.Bulgarian, Russian and Polish differ typologically – Bulgarian is an analytic language, Polish and Russian are synthetic. The parallel corpus should have compatible annotation, while taking into account the characteristic features of the selected languages.We hope that the Bulgarian-Polish-Russian parallel corpus will serve as a source of linguistic material of contrastive language studies and may prove to be a big help for linguists, translators, terminologists and students of linguistics. The results of our work will be available on the Internet.

  5. Numerical analysis of hydrodynamic process of circular-translational-moving polishing (CTMP)

    Institute of Scientific and Technical Information of China (English)

    Wenjie ZHAI; Changxiong LIU; Yingchun LIANG

    2008-01-01

    By keeping a pad moving relative to a wafer along a circular path without rotation, we developed a polishing technique called circular-translational-moving polishing (CTMP), which permits multidirectional polish-ing of the work piece and thus bears the advantage of isotropic polishing and a potential increase of material removal rate (MRR) on the wafer. To illuminate the mechanisms of CTMP and determine the optimum pro-cess variables in a CTMP process, a three-dimensional hydrodynamic lubrication model for CTMP with a smooth and rigid pad under a quasi-stable state is estab-lished in a polar coordinate system. The model equations are further calculated numerically by the finite difference method. The instantaneous distribution of fluid pressure is obtained, which shows that a negative pressure exists. The reason for negative pressure in CTMP and its effect on polishing is discussed. Moreover, the nominal clear-ance of the fluid film, roll, and pitch angles under different working conditions are obtained in terms of the applied load, moments, and polishing velocity. The obtained numerical analysis can be used as guidance for choosing operation parameters in a practical CTMP application.

  6. 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...

  7. The Influence of Surface Polish and Beverages on the Roughness of Nanohybrid and Microhybri Resin Composites

    Directory of Open Access Journals (Sweden)

    Sadeghi M

    2016-03-01

    Full Text Available Statement of the Problem: Surface roughness is a key factor in the aesthetics of restorative dentistry as it can determine the clinical quality and success of restorative materials. The chemical process of dissolution in the presence of mechanical forces can accelerate the surface roughness of tooth-coloured restorative materials. Objectives: To determine the degree of surface roughness of a microhybrid and a nanohybrid resin composite after polishing and immersion in various solutions. Materials and Methods: Two resin composites were used : a microhybrid (Gradia direct, GC, and a nanohybrid (Ice, SDI. A total of 54 disc-shaped specimens were prepared for each composite and immersed in distilled water incubated at 37 °C for 24 hours. After 24 h, the baseline measurement for surface roughness (Ra was performed and the specimens were divided into 3 groups of 18 and tested with unpolished or after polishing with Sof-Lex disc and Enhance point systems. Specimens in each group were subdivided into 3 subgroups (n = 6 and immersed in 3 solutions (distilled water, coffee, and cola for 7 days incubated at 37 °C. After 7 days, the specimens were rinsed with tap water for 10 seconds, dried with paper towel and Ra was measured again. Two randomly selected specimens of each group were sputter coated with gold and examined using a Field-Emission Scanning Electron Microscope (SEM. Results: Gradia direct showed a greater Ra than ice in all solutions for all polishing systems (p < 0.001. Specimens polished with Enhance point revealed a significantly greater roughness than Sof-Lex discs and both showed greater Ra than unpolished specimens. Specimens immersed in coffee exhibited significantly greater surface roughness than that of distilled water (p < 0.05 and cola (p < 0.001. Conclusions: Nano-hybrid composite showed a significantly smoother surface than microhybrid. Coffee exhibited the highest Ra compared to distilled water and cola. Enhance point revealed

  8. Mechanical Erosion in a Tropical River Basin in Southeastern Brazil: Chemical Characteristics and Annual Fluvial Transport Mechanisms

    Directory of Open Access Journals (Sweden)

    Alexandre Martins Fernandes

    2012-01-01

    Full Text Available This study aims to evaluate the mechanical erosion processes that occur in a tropical river basin, located in the São Paulo state, southeastern Brazil, through the chemical characterization of fine suspended sediments and the transport mechanisms near the river mouth, from March 2009 to September 2010. The chemical characterization indicated the predominance of SiO2, Al2O3, and Fe2O3 and showed no significant seasonal influences on the major element concentrations, expressed as oxides. The concentration variations observed were related to the mobility of chemical species. The evaluation of the rock-alteration degree indicated that the physical weathering was intense in the drainage basin. The fine suspended sediments charge was influenced by the variation discharges throughout the study period. The solid charge estimate of the surface runoff discharge was four times higher in the rainy season than the dry season. The transport of fine suspended sediments at the Sorocaba River mouth was 55.70 t km−2 a−1, corresponding to a specific physical degradation of 37.88 m Ma−1, a value associated with the mechanical erosion rate that corresponds to the soil thickness reduction in the drainage basin.

  9. 3D thermo-chemical-mechanical analysis of the pultrusion process

    DEFF Research Database (Denmark)

    Baran, Ismet; Hattel, Jesper Henri; Tutum, Cem C.

    2013-01-01

    In the present study, a 3D Eulerian thermo-chemical analysis is sequentially coupled with a 3D Lagrangian quasi static mechanical analysis of the pultrusion process. The temperature and degree of cure profiles at the steady state are first calculated in the thermo-chemical analysis....... In the mechanical analysis, the developments of the process induced stresses and distortions during the process are predicted using the already obtained temperature and degree of cure profiles together with the glass transition temperature. The predictions of the transverse transient stresses and distortions...... are found to be similar as compared to the available data in the literature. Using the proposed 3D mechanical analysis, different mechanical behaviour is obtained for the longitudinal stress development as distinct from the stress development in the transverse directions. Even though the matrix material...

  10. The Radical Pair Mechanism and the Avian Chemical Compass: Quantum Coherence and Entanglement

    CERN Document Server

    Zhang, Yiteng; Kais, Sabre

    2015-01-01

    We review the spin radical pair mechanism which is a promising explanation of avian navigation. This mechanism is based on the dependence of product yields on (1) the hyperfine interaction involving electron spins and neighboring nuclear spins and (2) the intensity and orientation of the geomagnetic field. One surprising result is that even at ambient conditions quantum entanglement of electron spins can play an important role in avian magnetoreception. This review describes the general scheme of chemical reactions involving radical pairs generated from singlet and triplet precursors; the spin dynamics of the radical pairs; and the magnetic field dependence of product yields caused by the radical pair mechanism. The main part of the review includes a description of the chemical compass in birds. We review: the general properties of the avian compass; the basic scheme of the radical pair mechanism; the reaction kinetics in cryptochrome; quantum coherence and entanglement in the avian compass; and the effects o...

  11. Compressive elastic moduli and polishing performance of non-rigid core/shell structured PS/SiO{sub 2} composite abrasives evaluated by AFM

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Ailian [College of Mechanical and Energy Engineering, Changzhou University, Changzhou, Jiangsu 213016 (China); Mu, Weibin [School of Materials Science and Engineering, Changzhou University, Changzhou, Jiangsu 213164 (China); Chen, Yang, E-mail: cy.jpu@126.com [School of Materials Science and Engineering, Changzhou University, Changzhou, Jiangsu 213164 (China)

    2014-01-30

    The core/shell structured polystyrene (PS)/SiO{sub 2} composite microspheres with different silica shell morphology were synthesized by a modified Stöber method. As confirmed by transmission electron microscopy (TEM), the rough discontinuous shell consisted of separate SiO{sub 2} nanoparticles for composite-A, while the smooth continuous one was composed of amorphous silica network for composite-B. Atomic force microscopy (AFM) was employed to probe the compressive Young's moduli (E) and chemical mechanical polishing (CMP) performances of the as-prepared PS/SiO{sub 2} composite microspheres. On the basis of the Hertzian contact mechanics, the calculated E values of the PS microspheres, composite-A and composite-B were 2.9 ± 0.4, 5.1 ± 1.2 and 6.0 ± 1.2 GPa, respectively. Compared to traditional abrasives, thermally grown silicon oxide wafers after polished by the core/shell PS/SiO{sub 2} composite abrasives obtained a lower root mean square roughness and a higher material removal rate value. In addition, there is an obvious effect of shell morphology of the composites on oxide CMP performance and structural stability during polishing process. This approach would provide a basis for understanding the actual role of organic/inorganic core/shell composite abrasives in the material removal process of CMP.

  12. Mechanism for the Environmental Process & Ecological Effects of Typical Chemical Pollutants

    Institute of Scientific and Technical Information of China (English)

    XU Xiaobai; WANG Liansheng; DAI Shugui; HUANG Yuyao

    2007-01-01

    @@ Principally being engaged in the field of earth sciences, this research project explores the mechanism which governs the environmental process of some typical chemical contaminants and their eco-toxic effects at various levels. The research project features the following achievements:

  13. A reconsideration for forming mechanism of optic fiber probe fabricated by static chemical etching

    Science.gov (United States)

    Chen, Yiru; Shen, Ruiqi

    2016-07-01

    The studies on the mechanism of static chemical etching are supplemented in this paper. Surface tension and diffusion effect are both taken into account. Theoretical analysis and data fitting show that the slant angle of the liquid-liquid interface leads to the maximum liquid rising, when diffusion effect is negligible.

  14. Protein structure validation and refinement using amide proton chemical shifts derived from quantum mechanics

    DEFF Research Database (Denmark)

    Christensen, Anders Steen; Linnet, Troels Emtekær; Borg, Mikael;

    2013-01-01

    We present the ProCS method for the rapid and accurate prediction of protein backbone amide proton chemical shifts - sensitive probes of the geometry of key hydrogen bonds that determine protein structure. ProCS is parameterized against quantum mechanical (QM) calculations and reproduces high level...

  15. Lifetimes of organic photovoltaics: Combining chemical and physical characterisation techniques to study degradation mechanisms

    DEFF Research Database (Denmark)

    Norrman, K.; Larsen, N.B.; Krebs, Frederik C

    2006-01-01

    Degradation mechanisms of a photovoltaic device with an Al/C-60/C-12-PSV/PEDOT:PSS/ITO/glass geometry was studied using a combination of in-plane physical and chemical analysis techniques: TOF-SIMS, AFM, SEM, interference microscopy and fluorescence microscopy. A comparison was made between...

  16. Rescue of vasopressin V2 receptor mutants by chemical chaperones: specificity and mechanism.

    NARCIS (Netherlands)

    Robben, J.H.; Sze, M.; Knoers, N.V.A.M.; Deen, P.M.T.

    2006-01-01

    Because missense mutations in genetic diseases of membrane proteins often result in endoplasmic reticulum (ER) retention of functional proteins, drug-induced rescue of their cell surface expression and understanding the underlying mechanism are of clinical value. To study this, we tested chemical ch

  17. The mechanical properties of thin alumina film deposited by metal-organic chemical vapour deposition

    NARCIS (Netherlands)

    Haanappel, V.A.C.; Gellings, P.J.; Vendel, van de D.; Metselaar, H.S.C.; Corbach, van H.D.; Fransen, T.

    1995-01-01

    Amorphous alumina films were deposited by metal-organic chemical vapour deposition (MOCVD) on stainless steel, type AISI 304. The MOCVD experiments were performed in nitrogen at low and atmospheric pressures. The effects of deposition temperature, growth rate and film thickness on the mechanical pro

  18. Use of Chemical Mixtures to Differentiate Mechanisms of Endocrine Action in a Small Fish Model

    Science.gov (United States)

    Various assays with adult fish have been developed to identify potential endocrine-disrupting chemicals (EDCs) which may cause toxicity via alterations in the hypothalamic-pituitary-gonadal (HPG) axis via different mechanisms/modes of action (MOA). These assays can be sensitive ...

  19. Structure-mechanism-based engineering of chemical regulators targeting distinct pathological factors in Alzheimer's disease

    Science.gov (United States)

    Beck, Michael W.; Derrick, Jeffrey S.; Kerr, Richard A.; Oh, Shin Bi; Cho, Woo Jong; Lee, Shin Jung C.; Ji, Yonghwan; Han, Jiyeon; Tehrani, Zahra Aliakbar; Suh, Nayoung; Kim, Sujeong; Larsen, Scott D.; Kim, Kwang S.; Lee, Joo-Yong; Ruotolo, Brandon T.; Lim, Mi Hee

    2016-10-01

    The absence of effective therapeutics against Alzheimer's disease (AD) is a result of the limited understanding of its multifaceted aetiology. Because of the lack of chemical tools to identify pathological factors, investigations into AD pathogenesis have also been insubstantial. Here we report chemical regulators that demonstrate distinct specificity towards targets linked to AD pathology, including metals, amyloid-β (Aβ), metal-Aβ, reactive oxygen species, and free organic radicals. We obtained these chemical regulators through a rational structure-mechanism-based design strategy. We performed structural variations of small molecules for fine-tuning their electronic properties, such as ionization potentials and mechanistic pathways for reactivity towards different targets. We established in vitro and/or in vivo efficacies of the regulators for modulating their targets' reactivities, ameliorating toxicity, reducing amyloid pathology, and improving cognitive deficits. Our chemical tools show promise for deciphering AD pathogenesis and discovering effective drugs.

  20. Smoking characteristics of Polish immigrants in Dublin

    Directory of Open Access Journals (Sweden)

    Zatonski Witold

    2008-12-01

    Full Text Available Abstract 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 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 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.

  1. 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.

  2. Direct imaging of mechanical and chemical gradients across the thickness of graded organosilicone microwave PECVD coatings.

    Science.gov (United States)

    Hall, Colin J; Murphy, Peter J; Griesser, Hans J

    2014-01-22

    The characterization of variations in the chemical composition and ensuing mechanical properties across the thickness of coatings with continuously varying compositions through their thickness (graded coatings) presents considerable challenges for current analytical techniques in materials science. We report here the direct imaging of nanomechanical and chemical gradients across cross-sections of an organosilicone coating fabricated via microwave plasma enhanced chemical vapor deposition (PECVD). Cross-sectional nanoindentation was used to determine the mechanical properties of uniform and graded organosilicone coatings. Both hardness and modulus across the coatings were directly measured. Additionally, "modulus mapping" on cross-sections was used to map the complex modulus. For the graded coating, it was found that variations in the complex modulus was predominantly due to varying storage modulus. It was observed that at the interface with the substrate there was a low storage modulus, which linearly increased to a relatively high storage modulus at the surface. It is proposed that the increase in stiffness, from the substrate interface to the outer surface, is due to the increasing content of a cross-linked O-Si-O network. This mechanical gradient has been linked to a change in the Si:O ratio via direct compositional mapping using ToF-SIMS. Direct mapping of the mechanical and compositional gradients across these protective coatings provides insight into the changes in properties with depth and supports optimization of the critical mechanical performance of PECVD graded coatings.

  3. Chemical reaction of hexagonal boron nitride and graphite nanoclusters in mechanical milling systems

    Energy Technology Data Exchange (ETDEWEB)

    Muramatsu, Y.; Grush, M.; Callcott, T.A. [Univ. of Tennessee, Knoxville, TN (United States)] [and others

    1997-04-01

    Synthesis of boron-carbon-nitride (BCN) hybrid alloys has been attempted extensively by many researchers because the BCN alloys are considered an extremely hard material called {open_quotes}super diamond,{close_quotes} and the industrial application for wear-resistant materials is promising. A mechanical alloying (MA) method of hexagonal boron nitride (h-BN) with graphite has recently been studied to explore the industrial synthesis of the BCN alloys. To develop the MA method for the BCN alloy synthesis, it is necessary to confirm the chemical reaction processes in the mechanical milling systems and to identify the reaction products. Therefore, the authors have attempted to confirm the chemical reaction process of the h-BN and graphite in mechanical milling systems using x-ray absorption near edge structure (XANES) methods.

  4. Applicability of random sequential adsorption algorithm for simulation of surface plasma polishing kinetics

    Science.gov (United States)

    Minárik, Stanislav; Vaňa, Dušan

    2015-11-01

    Applicability of random sequential adsorption (RSA) model for the material removal during a surface plasma polishing is discussed. The mechanical nature of plasma polishing process is taken into consideration in modified version of RSA model. During the plasma polishing the surface layer is aligned such that molecules of material are removed from the surface mechanically as a consequence of the surface deformation induced by plasma particles impact. We propose modification of RSA technique to describe the reduction of material on the surface provided that sequential character of molecules release from the surface is maintained throughout the polishing process. This empirical model is able to estimate depth profile of material density on the surface during the plasma polishing. We have shown that preliminary results obtained from this model are in good agreement with experimental results. We believe that molecular dynamics simulation of the polishing process, possibly also other types of surface treatment, can be based on this model. However influence of material parameters and processing conditions (including plasma characteristics) must be taken into account using appropriate model variables.

  5. AFNMR: automated fragmentation quantum mechanical calculation of NMR chemical shifts for biomolecules

    Energy Technology Data Exchange (ETDEWEB)

    Swails, Jason [Rutgers University, Department of Chemistry and Chemical Biology and BioMaPS Institute (United States); Zhu, Tong; He, Xiao, E-mail: xiaohe@phy.ecnu.edu.cn [East China Normal University, State Key Laboratory of Precision Spectroscopy, Institute of Theoretical and Computational Science (China); Case, David A., E-mail: case@biomaps.rutgers.edu [Rutgers University, Department of Chemistry and Chemical Biology and BioMaPS Institute (United States)

    2015-10-15

    We evaluate the performance of the automated fragmentation quantum mechanics/molecular mechanics approach (AF-QM/MM) on the calculation of protein and nucleic acid NMR chemical shifts. The AF-QM/MM approach models solvent effects implicitly through a set of surface charges computed using the Poisson–Boltzmann equation, and it can also be combined with an explicit solvent model through the placement of water molecules in the first solvation shell around the solute; the latter substantially improves the accuracy of chemical shift prediction of protons involved in hydrogen bonding with solvent. We also compare the performance of AF-QM/MM on proteins and nucleic acids with two leading empirical chemical shift prediction programs SHIFTS and SHIFTX2. Although the empirical programs outperform AF-QM/MM in predicting chemical shifts, the differences are in some cases small, and the latter can be applied to chemical shifts on biomolecules which are outside the training set employed by the empirical programs, such as structures containing ligands, metal centers, and non-standard residues. The AF-QM/MM described here is implemented in version 5 of the SHIFTS software, and is fully automated, so that only a structure in PDB format is required as input.

  6. EFFECT OF THERMAL TREATMENT ON THE CHEMICAL COMPOSITION AND MECHANICAL PROPERTIES OF BIRCH AND ASPEN

    Directory of Open Access Journals (Sweden)

    Duygu Kocaefe

    2008-05-01

    Full Text Available The high temperature treatment of wood is one of the alternatives to chemical treatment. During this process, the wood is heated to higher temperatures than those of conventional drying. The wood structure changes due to decomposition of hemicelluloses, ramification of lignin, and crystallization of cellulose. The wood becomes less hygroscopic. These changes improve the dimensional stability of wood, increase its resistance to micro-organisms, darken its color, and modify its hardness. However, wood also might loose some of its elasticity. Consequently, the heat treatment conditions have to be optimized. Therefore, it is important to understand the transformation of the chemical structure of wood caused by the treatment. In this study, the modification of the surface composition of the wood was followed with Fourier transform infrared spectroscopy (FTIR and inverse gas chromatography (IGC under different experimental conditions. The effect of maximum treatment temperatures on the chemical composition of Canadian birch and aspen as well as the correlations between their chemical transformation and different mechanical properties are presented. FTIR analysis results showed that the heat treatment affected the chemical composition of birch more compared to that of aspen. The results of IGC tests illustrated that the surfaces of the aspen and birch became more basic with heat treatment. The mechanical properties were affected by degradation of hemicellulose, ramification of lignin and cellulose crystallization.

  7. Chemical-mechanical stability of the hierarchical structure of shell nacre

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    The hierarchical structure and mechanical property of shell nacre are experimentally investigated from the new aspects of chemical stability and chemistry-mechanics coupling. Through chemical deproteinization or demineralization methods together with characterization techniques at micro/nano scales,it is found that the nacre of abalone,haliotis discus hannai,contains a hierarchical structure stacked with irregular aragonite platelets and interplatelet organic matrix thin layers. Yet the aragonite platelet itself is a nanocomposite consisting of nanoparticles and intraplatelet organic matrix framework. The mean diameter of the nanoparticles and the distribution of framework are quite different for different platelets. Though the interplatelet and in-traplatelet organic matrix can be both decomposed by sodium hydroxide solution,the chemical stability of individual aragonite platelets is much higher than that of the microstructure stacked with them. Further,macroscopic bending test or nanoindentation experiment is performed on the micro/nanostructure of nacre after sodium hydroxide treatment. It is found that the Young’s modulus of both the stacked microstructure and nanocomposite platelet reduced. The reduction of the microstructure is more remark than that of the platelet. Therefore the chemical-mechanical stability of the nanocomposite platelet itself is much higher than that of the stacked microstructure of nacre.

  8. Sediment losses from forest management: mechanical vs. chemical site preparation after clearcutting

    Energy Technology Data Exchange (ETDEWEB)

    Beasley, R.S.; Granillo, A.B.; Zillmer, V.

    The comparative effects of mechanical and chemical site preparation water yields and sediment losses following forest clearcutting were evaluated over a 4-yr period in the Athens Plateau area of southwestern Arkansas. After 1 yr of pretreatment measurements, three forested water sheds were clearcut and the residual vegetation and debris were sheared and windrowed but not burned. Three watersheds were clearcut in a similar manner, but received chemical site preparation. Residual trees on two watersheds were injected with 2-4, D amine; the third watershed was aerially sprayed with a mixture of Tordon (active ingredient: picloram (4-amino-3,5,6-trichloropicoline acid)) and Garlon (active ingredient; triclopyr (3,5,6-trichloro-2-pyridinyloxyacetic acid)). Three additional watersheds were left undisturbed for controls. Mean annual sediment losses on the mechanically, site prepared watersheds during the first posttreatment year were significantly higher than those from either the chemically site prepared watersheds or controls. Chemical site preparation did not significantly increase sediment losses. Although 2nd yr losses for the mechanical site preparation and control treatments doubled over 1st-yr levels, no significant treatment effect was detected for either site preparation treatment. Third-year losses decreased below 1st-yr losses for all treatments but not to pretreatment year levels. The relatively sharp declines in sediment losses during the third posttreatment year were attributed to rapid regrowth of natural vegetation on the sites.

  9. Evaluation and Development of Chemical Kinetic Mechanism Reduction Scheme for Biodiesel and Diesel Fuel Surrogates

    DEFF Research Database (Denmark)

    Poon, Hiew Mun; Ng, Hoon Kiat; Gan, Suyin;

    2013-01-01

    The aim of this study is to evaluate the existing chemical kinetic mechanism reduction techniques. From here, an appropriate reduction scheme was developed to create compact yet comprehensive surrogate models for both diesel and biodiesel fuels for diesel engine applications. The reduction......-dimensional computational fluid dynamics (CFD) study. A new reduction scheme was therefore formulated. A 68-species mechanism for biodiesel surrogate and a 49-species mechanism for diesel surrogate were successfully derived from the respective detailed mechanisms. An overall 97% reduction in species number......-hexadecane mechanism is expected to be a better representative of surrogate component for various transportation fuels such as biodiesel. Additionally, it can be applied to predict the reactivity of other n-alkane or interchange with one another for kinetic and CFD simulations....

  10. A micro-mapping strategy to investigate mechanical and chemical mass transport in migmatite

    Science.gov (United States)

    Lanari, Pierre; Riel, Nicolas

    2016-04-01

    Migmatites are fantastic objects to study both mechanical and chemical mass transport occurring at mm to cm-scale. However, migmatitic outcrops are the result of complex space and time interactions between (i) melt producing reactions, (ii) melt gain/loss and (iii) retrograde reactions. This succession of events is recorded in the minerals and microstructures of migmatites, and accounts for their apparent complexity. In order to explore the controlling parameters of these chemico-mechanical mass transport, it is thus necessary to characterize in great details the compositional changes between the different migmatitic domains, such as between leucosome and residuum. In this contribution we show how suitable local effective bulk (LEB) compositions can be derived by means of standardized microprobe X-ray images, using the program XMapTools. For chemically heterogeneous samples, such as migmatites, these LEB allow to forward model the stable mineral assemblages for each domain. Those thermodynamic models are used to investigate the conditions of leucosome-residuum separation. The studied sample is a metapelite embedded within a metasedimentary xenolith in the Marcabeli pluton, El Oro Complex, Ecuador. The sample exhibits complex mineral patterns due to local melt redistribution (at mm to cm-scale). Such physical mass transport involves major changes that affect the local chemical composition observed today. At the same time gradients in chemical potential can be established between adjacent domains such as residuum and leucosome, thus triggering chemical interaction. Diffusive transport between domains aims to reduce such chemical potential gradients. Along a modelled P-T path the chemical and mineralogical evolution of micro-domains can be reconstructed for (at least the reactive parts of) the crystallization history.

  11. Evidence from pharmacology and pathophysiology suggests that chemicals with dissimilar mechanisms of action could be of bigger concern in the toxicological risk assessment of chemical mixtures than chemicals with a similar mechanism of action

    DEFF Research Database (Denmark)

    Hadrup, Niels

    2014-01-01

    concomitantly contribute to the pathophysiology, suggesting that a grouping based on common target organs may also be inefficient. A better option may be to prioritise chemicals on the basis of potency and risk of exposure. In conclusion, there are arguments to suggest that we should concomitantly consider all...... mechanisms of action, similar modes of action or with common target organs. In the European Union, efforts are currently being made to subgroup chemicals according to this need. However, it remains to be determined whether this is the best strategy to obtain data for risk assessment. In conditions...... such as cancer or HIV, it is generally recognised that pharmacological combination therapy targeting different mechanisms of action is more effective than a strategy where only one mechanism is targeted. Moreover, in diseases such as acute myocardial infarction and congestive heart failure, several organ systems...

  12. Utilizing toxicogenomic data to understand chemical mechanism of action in risk assessment

    Energy Technology Data Exchange (ETDEWEB)

    Wilson, Vickie S., E-mail: wilson.vickie@epa.gov [National Health and Environmental Effects Research Laboratory, Office of Research and Development, U.S. Environmental Protection Agency, Research Triangle Park, NC 27711 (United States); Keshava, Nagalakshmi [National Center for Environmental Assessment, Office of Research and Development, U.S. Environmental Protection Agency, 1200 Pennsylvania Ave., NW, Washington, DC 20460 (United States); Hester, Susan [National Health and Environmental Effects Research Laboratory, Office of Research and Development, U.S. Environmental Protection Agency, Research Triangle Park, NC 27711 (United States); Segal, Deborah; Chiu, Weihsueh [National Center for Environmental Assessment, Office of Research and Development, U.S. Environmental Protection Agency, 1200 Pennsylvania Ave., NW, Washington, DC 20460 (United States); Thompson, Chad M. [ToxStrategies, Inc., 23501 Cinco Ranch Blvd., Suite G265, Katy, TX 77494 (United States); Euling, Susan Y. [National Center for Environmental Assessment, Office of Research and Development, U.S. Environmental Protection Agency, 1200 Pennsylvania Ave., NW, Washington, DC 20460 (United States)

    2013-09-15

    The predominant role of toxicogenomic data in risk assessment, thus far, has been one of augmentation of more traditional in vitro and in vivo toxicology data. This article focuses on the current available examples of instances where toxicogenomic data has been evaluated in human health risk assessment (e.g., acetochlor and arsenicals) which have been limited to the application of toxicogenomic data to inform mechanism of action. This article reviews the regulatory policy backdrop and highlights important efforts to ultimately achieve regulatory acceptance. A number of research efforts on specific chemicals that were designed for risk assessment purposes have employed mechanism or mode of action hypothesis testing and generating strategies. The strides made by large scale efforts to utilize toxicogenomic data in screening, testing, and risk assessment are also discussed. These efforts include both the refinement of methodologies for performing toxicogenomics studies and analysis of the resultant data sets. The current issues limiting the application of toxicogenomics to define mode or mechanism of action in risk assessment are discussed together with interrelated research needs. In summary, as chemical risk assessment moves away from a single mechanism of action approach toward a toxicity pathway-based paradigm, we envision that toxicogenomic data from multiple technologies (e.g., proteomics, metabolomics, transcriptomics, supportive RT-PCR studies) can be used in conjunction with one another to understand the complexities of multiple, and possibly interacting, pathways affected by chemicals which will impact human health risk assessment.

  13. Wellbore Stability in Oil and Gas Drilling with Chemical-Mechanical Coupling

    Directory of Open Access Journals (Sweden)

    Chuanliang Yan

    2013-01-01

    Full Text Available Wellbore instability in oil and gas drilling is resulted from both mechanical and chemical factors. Hydration is produced in shale formation owing to the influence of the chemical property of drilling fluid. A new experimental method to measure diffusion coefficient of shale hydration is given, and the calculation method of experimental results is introduced. The diffusion coefficient of shale hydration is measured with the downhole temperature and pressure condition, then the penetration migrate law of drilling fluid filtrate around the wellbore is calculated. Furthermore, the changing rules of shale mechanical properties affected by hydration and water absorption are studied through experiments. The relationships between shale mechanical parameters and the water content are established. The wellbore stability model chemical-mechanical coupling is obtained based on the experimental results. Under the action of drilling fluid, hydration makes the shale formation softened and produced the swelling strain after drilling. This will lead to the collapse pressure increases after drilling. The study results provide a reference for studying hydration collapse period of shale.

  14. Research Update: Mechanical properties of metal-organic frameworks – Influence of structure and chemical bonding

    Directory of Open Access Journals (Sweden)

    Wei Li

    2014-12-01

    Full Text Available Metal-organic frameworks (MOFs, a young family of functional materials, have been attracting considerable attention from the chemistry, materials science, and physics communities. In the light of their potential applications in industry and technology, the fundamental mechanical properties of MOFs, which are of critical importance for manufacturing, processing, and performance, need to be addressed and understood. It has been widely accepted that the framework topology, which describes the overall connectivity pattern of the MOF building units, is of vital importance for the mechanical properties. However, recent advances in the area of MOF mechanics reveal that chemistry plays a major role as well. From the viewpoint of materials science, a deep understanding of the influence of chemical effects on MOF mechanics is not only highly desirable for the development of novel functional materials with targeted mechanical response, but also for a better understanding of important properties such as structural flexibility and framework breathing. The present work discusses the intrinsic connection between chemical effects and the mechanical behavior of MOFs through a number of prototypical examples.

  15. Deterministic polishing from theory to practice

    Science.gov (United States)

    Hooper, Abigail R.; Hoffmann, Nathan N.; Sarkas, Harry W.; Escolas, John; Hobbs, Zachary

    2015-10-01

    Improving predictability in optical fabrication can go a long way towards increasing profit margins and maintaining a competitive edge in an economic environment where pressure is mounting for optical manufacturers to cut costs. A major source of hidden cost is rework - the share of production that does not meet specification in the first pass through the polishing equipment. Rework substantially adds to the part's processing and labor costs as well as bottlenecks in production lines and frustration for managers, operators and customers. The polishing process consists of several interacting variables including: glass type, polishing pads, machine type, RPM, downforce, slurry type, baume level and even the operators themselves. Adjusting the process to get every variable under control while operating in a robust space can not only provide a deterministic polishing process which improves profitability but also produces a higher quality optic.

  16. Electro Polishing of Niobium Cavities at DESY

    CERN Document Server

    Matheisen, A; Morales, H; Petersen, B; Schmoekel, M; Steinhau-Kühl, N

    2004-01-01

    At DESY a facility for electro polishing (EP) of the super conducting (s.c.) TESLA/TTF cavities have been built and is operational since summer 2003. The EP infrastructure is capable to handle single-cell structures and the standard TESLA/ TTF nine-cell cavities. Several electro polishing processes have been made since and acceleration voltage up to 40 MV/m have been reached in nine cell structures. We report on measurements and experiences gained since 2003 as well as on handling procedures developed for the preparation of electro polished resonators. Specific data like heat production, variation of current density and bath aging will be presented. Another important point for reproducible results is the quality control of the electro polishing process. First quality control steps to be implanted in the EP procedure for large-scale production will be described.

  17. Polish martial law the crisis of communism

    OpenAIRE

    Dmitrukowski, Tomasz

    2009-01-01

    In the summer of 1980, Polish workers revolted against Communist corruption and Poland's failed economic system. In a wave of solidarity unprecedented in a Communist state, citizens challenged the government's authority as the legitimate decision making body. Striking workers throughout the country created the Solidarity Union. They demanded personal freedom, legalization of Solidarity, and an input into the government. Polish Communist leaders faced the choice of either executing the wishes ...

  18. 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’.

  19. Effect of mechanical activation on structure changes and reactivity in further chemical modification of lignin.

    Science.gov (United States)

    Zhao, Xiaohong; Zhang, Yanjuan; Hu, Huayu; Huang, Zuqiang; Yang, Mei; Chen, Dong; Huang, Kai; Huang, Aimin; Qin, Xingzhen; Feng, Zhenfei

    2016-10-01

    Lignin was treated by mechanical activation (MA) in a customized stirring ball mill, and the structure and reactivity in further esterification were studied. The chemical structure and morphology of MA-treated lignin and the esterified products were analyzed by chemical analysis combined with UV/vis spectrometer, FTIR,NMR, SEM and particle size analyzer. The results showed that MA contributed to the increase of aliphatic hydroxyl, phenolic hydroxyl, carbonyl and carboxyl groups but the decrease of methoxyl groups. Moreover, MA led to the decrease of particle size and the increase of specific surface area and roughness of surface in lignin. The reactivity of lignin was enhanced significantly for the increase of hydroxyl content and the improvement of mass transfer in chemical reaction caused by the changes of molecular structure and morphological structure. The process of MA is green and simple, and is an effective method for enhancing the reactivity of lignin. PMID:27344951

  20. 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.

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

    OpenAIRE

    Danuta Roszko; Roman Roszko

    2015-01-01

    Experimental Polish-Lithuanian Corpus with the Semantic Annotation ElementsIn 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.

  2. 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.

  3. Physical and chemical mechanisms in oxide-based resistance random access memory.

    Science.gov (United States)

    Chang, Kuan-Chang; Chang, Ting-Chang; Tsai, Tsung-Ming; Zhang, Rui; Hung, Ya-Chi; Syu, Yong-En; Chang, Yao-Feng; Chen, Min-Chen; Chu, Tian-Jian; Chen, Hsin-Lu; Pan, Chih-Hung; Shih, Chih-Cheng; Zheng, Jin-Cheng; Sze, Simon M

    2015-01-01

    In this review, we provide an overview of our work in resistive switching mechanisms on oxide-based resistance random access memory (RRAM) devices. Based on the investigation of physical and chemical mechanisms, we focus on its materials, device structures, and treatment methods so as to provide an in-depth perspective of state-of-the-art oxide-based RRAM. The critical voltage and constant reaction energy properties were found, which can be used to prospectively modulate voltage and operation time to control RRAM device working performance and forecast material composition. The quantized switching phenomena in RRAM devices were demonstrated at ultra-cryogenic temperature (4K), which is attributed to the atomic-level reaction in metallic filament. In the aspect of chemical mechanisms, we use the Coulomb Faraday theorem to investigate the chemical reaction equations of RRAM for the first time. We can clearly observe that the first-order reaction series is the basis for chemical reaction during reset process in the study. Furthermore, the activation energy of chemical reactions can be extracted by changing temperature during the reset process, from which the oxygen ion reaction process can be found in the RRAM device. As for its materials, silicon oxide is compatible to semiconductor fabrication lines. It is especially promising for the silicon oxide-doped metal technology to be introduced into the industry. Based on that, double-ended graphene oxide-doped silicon oxide based via-structure RRAM with filament self-aligning formation, and self-current limiting operation ability is demonstrated. The outstanding device characteristics are attributed to the oxidation and reduction of graphene oxide flakes formed during the sputter process. Besides, we have also adopted a new concept of supercritical CO2 fluid treatment to efficiently reduce the operation current of RRAM devices for portable electronic applications.

  4. Endocrine-disrupting chemicals use distinct mechanisms of action to modulate endocrine system function.

    Science.gov (United States)

    Henley, Derek V; Korach, Kenneth S

    2006-06-01

    The term endocrine-disrupting chemicals is used to define a structurally diverse class of synthetic and natural compounds that possess the ability to alter various components of the endocrine system and potentially induce adverse health effects in exposed individuals and populations. Research on these compounds has revealed that they use a variety of both nuclear receptor-mediated and non-receptor-mediated mechanisms to modulate different components of the endocrine system. This review will describe in vitro and in vivo studies that highlight the spectrum of unique mechanisms of action and biological effects of four endocrine-disrupting chemicals--diethylstilbestrol, genistein, di(n-butyl)phthalate, and methoxyacetic acid--to illustrate the diverse and complex nature of this class of compounds.

  5. NSR&D FY15 Final Report. Modeling Mechanical, Thermal, and Chemical Effects of Impact

    Energy Technology Data Exchange (ETDEWEB)

    Long, Christopher Curtis [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Ma, Xia [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Zhang, Duan Zhong [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2015-11-02

    The main goal of this project is to develop a computer model that explains and predicts coupled mechanical, thermal and chemical responses of HE under impact and friction insults. The modeling effort is based on the LANL-developed CartaBlanca code, which is implemented with the dual domain material point (DDMP) method to calculate complex and coupled thermal, chemical and mechanical effects among fluids, solids and the transitions between the states. In FY 15, we have implemented the TEPLA material model for metal and performed preliminary can penetration simulation and begun to link with experiment. Currently, we are working on implementing a shock to detonation transition (SDT) model (SURF) and JWL equation of state.

  6. Chemical weathering as a mechanism for the climatic control of bedrock river incision.

    Science.gov (United States)

    Murphy, Brendan P; Johnson, Joel P L; Gasparini, Nicole M; Sklar, Leonard S

    2016-04-14

    Feedbacks between climate, erosion and tectonics influence the rates of chemical weathering reactions, which can consume atmospheric CO2 and modulate global climate. However, quantitative predictions for the coupling of these feedbacks are limited because the specific mechanisms by which climate controls erosion are poorly understood. Here we show that climate-dependent chemical weathering controls the erodibility of bedrock-floored rivers across a rainfall gradient on the Big Island of Hawai'i. Field data demonstrate that the physical strength of bedrock in streambeds varies with the degree of chemical weathering, which increases systematically with local rainfall rate. We find that incorporating the quantified relationships between local rainfall and erodibility into a commonly used river incision model is necessary to predict the rates and patterns of downcutting of these rivers. In contrast to using only precipitation-dependent river discharge to explain the climatic control of bedrock river incision, the mechanism of chemical weathering can explain strong coupling between local climate and river incision.

  7. Topoisomerase I and II inhibitors: chemical structure, mechanisms of action and role in cancer chemotherapy

    Science.gov (United States)

    Dezhenkova, L. G.; Tsvetkov, V. B.; Shtil, A. A.

    2014-01-01

    The review summarizes and analyzes recent published data on topoisomerase I and II inhibitors as potential antitumour agents. Functions and the mechanism of action of topoisomerases are considered. The molecular mechanism of interactions between low-molecular-weight compounds and these proteins is discussed. Topoisomerase inhibitors belonging to different classes of chemical compounds are systematically covered. Assays for the inhibition of topoisomerases and the possibilities of using the computer-aided modelling for the rational design of novel drugs for cancer chemotherapy are presented. The bibliography includes 127 references.

  8. Influence of chemical heat treatment on the mechanical properties of paper knife-edge die

    OpenAIRE

    K. Dybowski; Kaczmarek, Ł.; R. Pietrasik; J. Smolik; Ł. Kołodziejczyk; Batory, D.; Gzik, M; M. Stegliński

    2009-01-01

    Purpose: In this article mechanical properties together with wear mechanism of paper knife-edge die made of A 681 steel with TiN, TiCN and DLC coating were analyzed. A Paper knife-edge die using in stamping machine, serves a map of complicated graphical projects. However wear resistance is strongly dependent on chemical composition of a paper mainly on the TiO2 content.Design/methodology/approach: In order to optimize the wear resistance of analyzed paper knife-edge die, influence of HS6-5-2 ...

  9. 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.

  10. Notes on the KIVA-2 software and chemically reactive fluid mechanics

    Science.gov (United States)

    Holst, M. J.

    1992-09-01

    Working notes regarding the mechanics of chemically reactive fluids with sprays, and their numerical simulation with the KIVA-2 software are presented. KIVA-2 is a large FORTRAN program developed at Los Alamos National Laboratory for internal combustion engine simulation. It is our hope that these notes summarize some of the necessary background material in fluid mechanics and combustion, explain the numerical methods currently used in KIVA-2 and similar combustion codes, and provide an outline of the overall structure of KIVA-2 as a representative combustion program, in order to aid the researcher in the task of implementing KIVA-2 or a similar combustion code on a massively parallel computer. The notes are organized into three parts as follows. In Part 1, a brief introduction to continuum mechanics, to fluid mechanics, and to the mechanics of chemically reactive fluids with sprays is presented. In Part 2, a close look at the governing equations of KIVA-2 is taken, and the methods employed in the numerical solution of these equations is discussed. Some conclusions are drawn and some observations are made in Part 3.

  11. The Physical-Chemical Mechanism of Water Stream Self-Purification

    CERN Document Server

    Mikhailovskii, V

    2000-01-01

    The self-purification process of water streams is studied and the physical-chemical mechanism of it is determined. The naturally occurring self-purification process at the Boyne River site is monitored. Experiments at several creeks and rivers in GTA area that induced the self-purification process are provided. As a result, the concentration of polluting agents in the water decreases up to 100 0epending on the site and pollutants.

  12. Development of a Next-Generation Environmental Chamber Facility for Chemical Mechanism and VOC Reactivity Research

    OpenAIRE

    Carter, W P L; Fitz, D; D. R. Cocker III; Malkina, I L; Bumiller, K; Sauer, C G; Pisano, J T; Bufalino, C; Song, C.

    2005-01-01

    A new state-of-the-art indoor environmental chamber facility for the study of atmospheric processes leading to the formation of ozone and secondary organic aerosol (SOA) has been constructed and characterized. The chamber is designed for atmospheric chemical mechanism evaluation at low reactant concentrations under well-controlled environmental conditions. It consists of two collapsible 90 m3 FEP Teflon film reactors on pressure-controlled moveable frameworks inside a temperature-controlled e...

  13. Identifying the causes of differences in ozone production from the CB05 and CBMIV chemical mechanisms

    OpenAIRE

    R. D. Saylor; A. F. Stein

    2011-01-01

    An investigation was conducted to identify the mechanistic differences between two versions of the carbon bond gas-phase chemical mechanism (CB05 and CBMIV) which consistently lead to larger ground-level ozone concentrations being produced in the CB05 version of the National Air Quality Forecasting Capability (NAQFC) modeling system even though the two parallel forecast systems utilize the same meteorology and base emissions and similar initial and boundary conditions. Box models of ea...

  14. Identifying the causes of differences in ozone production from the CB05 and CBMIV chemical mechanisms

    OpenAIRE

    R. D. Saylor; A. F. Stein

    2012-01-01

    An investigation was conducted to identify the mechanistic differences between two versions of the carbon bond gas-phase chemical mechanism (CB05 and CBMIV) which consistently lead to larger ground-level ozone concentrations being produced in the CB05 version of the National Air Quality Forecasting Capability (NAQFC) modeling system even though the two parallel forecast systems utilize the same meteorology and base emissions and similar initial and boundary conditions. Box models of each of t...

  15. Effects of Mechanical and Chemical Pretreatments of Zirconia or Fiber Posts on Resin Cement Bonding

    OpenAIRE

    Rui Li; Hui Zhou; Wei Wei; Chen Wang,; Ying Chun Sun; Ping Gao

    2015-01-01

    The bonding strength between resin cement and posts is important for post and core restorations. An important method of improving the bonding strength is the use of various surface pretreatments of the post. In this study, the surfaces of zirconia (fiber) posts were treated by mechanical and/or chemical methods such as sandblasting and silanization. The bonding strength between the zirconia (fiber) post and the resin cement was measured by a push-out method after thermocycling based on the ad...

  16. Rescue of vasopressin V2 receptor mutants by chemical chaperones: specificity and mechanism.

    OpenAIRE

    Robben, J.H.; Sze, M.; Knoers, N.V.A.M.; Deen, P. M. T.

    2006-01-01

    Because missense mutations in genetic diseases of membrane proteins often result in endoplasmic reticulum (ER) retention of functional proteins, drug-induced rescue of their cell surface expression and understanding the underlying mechanism are of clinical value. To study this, we tested chemical chaperones and sarco(endo)plasmic reticulum Ca2+ ATPase pump inhibitors on Madin-Darby canine kidney cells expressing nine ER-retained vasopressin type-2 receptor (V2R) mutants involved in nephrogeni...

  17. Postharvest Chemical, Sensorial and Physical-Mechanical Properties of Wild Apricot (Prunus armeniaca L.)

    OpenAIRE

    Evica MRATINIĆ; Bojan POPOVSKI; Tomo MILOŠEVIĆ; Melpomena POPOVSKA

    2011-01-01

    Some chemical, sensorial and physical-mechanical properties of 19 apricot genotypes and Hungarian Best (control) such as moisture content, soluble solids content, titratable acidity ratio and their ratio, fruit and stone mass, flesh/stone ratio, fruit dimensions (length, width, thickness), arithmetic and geometric mean diameter, sphericity, surface area and aspect ratio were determined. Their application is also discussed. The highest moisture content and stone mass observed in X-1/1/04 and X...

  18. Potential role of redox cycling as a mechanism for chemical teratogenesis

    Energy Technology Data Exchange (ETDEWEB)

    Juchau, M.R.; Fantel, A.G.; Harris, C.; Beyer, B.K.

    1986-12-01

    A survey of the literature indicates that several chemicals whose reduced metabolites are capable of undergoing redox cycling in biological systems also possess significant teratogenic properties when tested in vivo. The authors have initiated investigations to determine whether the embryotoxic effects of such chemicals could result from their redox cycling properties and whether redox cycling could be an important mechanism in chemical teratogenesis. In order to obviate the potentially confounding influences of maternal factors, the initial studies have been performed with a whole embryo culture system with redox cycling agents added directly to the culture medium. Several representative redox cycling agents including doxorubicin, paraquat, a series of nitroheterocycles, nitrosofluorene, and diethylstilbestrol (converted metabolically to redox cycling quinone/semiquinone radicals) have been investigated thus far. The nitroheterocycles which bear nitro groups with comparatively high redox potentials produced a striking, asymmetric defect involving primarily the right half of the prosencephalic and mesencephalic regions. The effect was exacerbated under conditions of low O/sub 2/ tension. Accumulated data to date strongly suggest that reduction of the nitro group is an essential feature in the embryotoxic mechanism. Quinones (doxorubicin, paraquat) and compounds metabolically converted to quinones (diethylstilbestrol) appeared to produce embryotoxic effects via mechanisms not associated with redox cycling. Nitrosofluorene embryotoxicity was markedly exacerbated by changes in both intra- and extracellular glutathione levels, but definitive dependence on a radical-mediated effect or redox cycling was not demonstrated.

  19. Protein structure validation and refinement using amide proton chemical shifts derived from quantum mechanics.

    Directory of Open Access Journals (Sweden)

    Anders S Christensen

    Full Text Available We present the ProCS method for the rapid and accurate prediction of protein backbone amide proton chemical shifts--sensitive probes of the geometry of key hydrogen bonds that determine protein structure. ProCS is parameterized against quantum mechanical (QM calculations and reproduces high level QM results obtained for a small protein with an RMSD of 0.25 ppm (r = 0.94. ProCS is interfaced with the PHAISTOS protein simulation program and is used to infer statistical protein ensembles that reflect experimentally measured amide proton chemical shift values. Such chemical shift-based structural refinements, starting from high-resolution X-ray structures of Protein G, ubiquitin, and SMN Tudor Domain, result in average chemical shifts, hydrogen bond geometries, and trans-hydrogen bond ((h3J(NC' spin-spin coupling constants that are in excellent agreement with experiment. We show that the structural sensitivity of the QM-based amide proton chemical shift predictions is needed to obtain this agreement. The ProCS method thus offers a powerful new tool for refining the structures of hydrogen bonding networks to high accuracy with many potential applications such as protein flexibility in ligand binding.

  20. Protein structure validation and refinement using amide proton chemical shifts derived from quantum mechanics

    CERN Document Server

    Christensen, Anders S; Borg, Mikael; Boomsma, Wouter; Lindorff-Larsen, Kresten; Hamelryck, Thomas; Jensen, Jan H

    2013-01-01

    We present the ProCS method for the rapid and accurate prediction of protein backbone amide proton chemical shifts - sensitive probes of the geometry of key hydrogen bonds that determine protein structure. ProCS is parameterized against quantum mechanical (QM) calculations and reproduces high level QM results obtained for a small protein with an RMSD of 0.25 ppm (r = 0.94). ProCS is interfaced with the PHAISTOS protein simulation program and is used to infer statistical protein ensembles that reflect experimentally measured amide proton chemical shift values. Such chemical shift-based structural refinements, starting from high-resolution X-ray structures of Protein G, ubiquitin, and SMN Tudor Domain, result in average chemical shifts, hydrogen bond geometries, and trans-hydrogen bond (h3JNC') spin-spin coupling constants that are in excellent agreement with experiment. We show that the structural sensitivity of the QM-based amide proton chemical shift predictions is needed to refine protein structures to this...

  1. 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...

  2. Identifying the causes of differences in ozone production from the CB05 and CBMIV chemical mechanisms

    Directory of Open Access Journals (Sweden)

    R. D. Saylor

    2012-02-01

    Full Text Available An investigation was conducted to identify the mechanistic differences between two versions of the carbon bond gas-phase chemical mechanism (CB05 and CBMIV which consistently lead to larger ground-level ozone concentrations being produced in the CB05 version of the National Air Quality Forecasting Capability (NAQFC modeling system even though the two parallel forecast systems utilize the same meteorology and base emissions and similar initial and boundary conditions. Box models of each of the mechanisms as they are implemented in the NAQFC were created and a set of 12 sensitivity simulations was designed. The sensitivity simulations independently probed the conceptual mechanistic differences between CB05 and CBMIV and were exercised over a 45-scenario simulation suite designed to emulate the wide range of chemical regimes encountered in a continental-scale atmospheric chemistry model. Results of the sensitivity simulations indicate that two sets of reactions that were included in the CB05 mechanism, but which were absent from the CBMIV mechanism, are the primary causes of the greater ozone production in the CB05 version of the NAQFC. One set of reactions recycles the higher organic peroxide species of CB05 (ROOH, resulting in additional photochemically reactive products that act to produce additional ozone in some chemical regimes. The other set of reactions recycles reactive nitrogen from less reactive forms back to NO2, increasing the effective NOx concentration of the system. In particular, the organic nitrate species (NTR, which was a terminal product for reactive nitrogen in the CBMIV mechanism, acts as a reservoir species in CB05 to redistribute NOx from major source areas to potentially NOx-sensitive areas where additional ozone may be produced in areas remote from direct NOx sources.

  3. Identifying the causes of differences in ozone production from the CB05 and CBMIV chemical mechanisms

    Directory of Open Access Journals (Sweden)

    R. D. Saylor

    2011-10-01

    Full Text Available An investigation was conducted to identify the mechanistic differences between two versions of the carbon bond gas-phase chemical mechanism (CB05 and CBMIV which consistently lead to larger ground-level ozone concentrations being produced in the CB05 version of the National Air Quality Forecasting Capability (NAQFC modeling system even though the two parallel forecast systems utilize the same meteorology and base emissions and similar initial and boundary conditions. Box models of each of the mechanisms as they are implemented in the NAQFC were created and a set of 12 sensitivity simulations was designed. The sensitivity simulations independently probed the conceptual mechanistic differences between CB05 and CBMIV and were exercised over a 45-scenario simulation suite designed to emulate the wide range of chemical regimes encountered in a continental-scale atmospheric chemistry model. Results of the sensitivity simulations indicate that two sets of reactions that were included in the CB05 mechanism, but which were absent from the CBMIV mechanism, are the primary causes of the greater ozone production in the CB05 version of the NAQFC. One set of reactions recycles the higher organic peroxide species of CB05 (ROOH, resulting in additional photochemically reactive products that act to produce additional ozone in some chemical regimes. The other set of reactions recycles reactive nitrogen from less reactive forms back to NO2, increasing the effective NOx concentration of the system. In particular, the organic nitrate species (NTR, which was a terminal product for reactive nitrogen in the CBMIV mechanism, acts as a reservoir species in CB05 to redistribute NOx from major source areas to potentially NOx-sensitive areas where additional ozone may be produced in areas remote from direct NOx sources.

  4. 大气化学机理的发展及应用%Development and Application of Atmospheric Chemical Mechanisms

    Institute of Scientific and Technical Information of China (English)

    石玉珍; 徐永福; 贾龙

    2012-01-01

    Atmospheric chemical mechanism is one of the most important components to study photochemical processes and develop air quality models. The development and application of several atmospheric chemical mechanisms were summarized. The simplified chemical mechanisms include Carbon Bond Mechanism (CBM), Statewide Air Pollution Research Center mechanism (SAPRC), Regional Acid Deposition Mechanism (RADM), and Regional Atmospheric Chemical Mechanism (RACM) which have been widely used in the past decades and the explicit chemical mechanisms contain Master Chemical Mechanism (MCM) and Common Representative Intermediates (CRI) which were developed rapidly in the past few years. The history, species, and lump styles of these mechanisms were compared. Meanwhile, the research of the evaluation to chemical mechanism by using chamber experiment data and the application of these chemical mechanisms in model development also summarized. Besides, the further demand to the development and improvement of chemical mechanisms was put forward.%大气化学机理是研究大气化学过程的重要手段和方法之一,也是发展空气质量模式必不可少的重要组成部分.作者综述了几种应用广泛的简化机理——碳键机理(Carbon Bond Mechanism,CBM)、加州大气污染研究中心机理(Statewide Air Pollution Research Center mechanism,SAPRC)、区域酸沉降机理(Regional Acid Deposition Mechanism,RADM)、区域大气化学机理(Regional Atmospheric Chemical Mechanism,RACM)以及详细化学机理——主要大气化学机理(Master Chemical Mechanism,MCM)和共同代表性中间体机理(Common Representative Intermediates,CRI)的发展及应用.对上述大气化学机理的产生、发展、包含的物种类型、集总方式等方面进行了对比分析,总结了采用烟雾箱数据评价大气化学机理的研究成果以及大气化学机理在模式发展方面的应用,并对大气化学机理的进一步发展与完善提出了需求.

  5. Comparison of Moringa Oleifera seeds oil characterization produced chemically and mechanically

    Science.gov (United States)

    Eman, N. A.; Muhamad, K. N. S.

    2016-06-01

    It is established that virtually every part of the Moringa oleifera tree (leaves, stem, bark, root, flowers, seeds, and seeds oil) are beneficial in some way with great benefits to human being. The tree is rich in proteins, vitamins, minerals. All Moringa oleifera food products have a very high nutritional value. They are eaten directly as food, as supplements, and as seasonings as well as fodder for animals. The purpose of this research is to investigate the effect of seeds particle size on oil extraction using chemical method (solvent extraction). Also, to compare Moringa oleifera seeds oil properties which are produced chemically (solvent extraction) and mechanically (mechanical press). The Moringa oleifera seeds were grinded, sieved, and the oil was extracted using soxhlet extraction technique with n-Hexane using three different size of sample (2mm, 1mm, and 500μm). The average oil yield was 36.1%, 40.80%, and 41.5% for 2mm, 1mm, and 500μm particle size, respectively. The properties of Moringa oleifera seeds oil were: density of 873 kg/m3, and 880 kg/m3, kinematic viscosity of 42.2mm2/s and 9.12mm2/s for the mechanical and chemical method, respectively. pH, cloud point and pour point were same for oil produced with both methods which is 6, 18°C and 12°C, respectively. For the fatty acids, the oleic acid is present with high percentage of 75.39%, and 73.60% from chemical and mechanical method, respectively. Other fatty acids are present as well in both samples which are (Gadoleic acid, Behenic acid, Palmitic acid) which are with lower percentage of 2.54%, 5.83%, and 5.73%, respectively in chemical method oil, while they present as 2.40%, 6.73%, and 6.04%, respectively in mechanical method oil. In conclusion, the results showed that both methods can produce oil with high quality. Moringa oleifera seeds oil appear to be an acceptable good source for oil rich in oleic acid which is equal to olive oil quality, that can be consumed in Malaysia where the olive oil

  6. The influence of chemical composition on structure and mechanical properties of austenitic Cr-Ni steels

    Directory of Open Access Journals (Sweden)

    A. Kurc-Lisiecka

    2013-12-01

    Full Text Available Purpose: The aim of the paper is to investigated the influence of the chemical composition on the structure and mechanical properties of austenitic Cr-Ni steels. Special attention was put on the effect of solution heat treatment on mechanical properties of examined steels. Design/methodology/approach: The examinations of static tensile tests were conducted on ZWICK 100N5A. Hardness measurements were made by Vickers method. The X-ray analyzes were realized with the use of Dron 2.0 diffractometer equipped with the lamp of the cobalt anode. The metallographic observations were carried out on LEICA MEF 4A light microscope. Findings: Results shown that after solution heat treatment the values of strength properties (UTS, YS0.2 and hardness (HV of both investigated steels decrease and their elongation (EL increases. The X5CrNi18-8 steel in delivery state shown austenitic microstructure with twins and numerous non-metallic inclusions, while in steel X10CrNi18-8 revealed a austenitic microstructure with numerous slip bands in areas with deformation martensite α’. The examined steels after solution heat treatment followed by water-cooling has the structure of austenite. Research limitations/implications: To investigate in more detail the influence of chemical composition on structure and mechanical properties the examinations of substructure by TEM should be conducted. Originality/value: The relationship between the solution heat treatment, structure and mechanical properties of investigated steels was specified.

  7. The Radical Pair Mechanism and the Avian Chemical Compass: Quantum Coherence and Entanglement

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Yiteng [Purdue Univ., West Lafayette, IN (United States); Kais, Sabre [Purdue Univ., West Lafayette, IN (United States); Berman, Gennady Petrovich [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2015-02-02

    We review the spin radical pair mechanism which is a promising explanation of avian navigation. This mechanism is based on the dependence of product yields on 1) the hyperfine interaction involving electron spins and neighboring nuclear spins and 2) the intensity and orientation of the geomagnetic field. One surprising result is that even at ambient conditions quantum entanglement of electron spins can play an important role in avian magnetoreception. This review describes the general scheme of chemical reactions involving radical pairs generated from singlet and triplet precursors; the spin dynamics of the radical pairs; and the magnetic field dependence of product yields caused by the radical pair mechanism. The main part of the review includes a description of the chemical compass in birds. We review: the general properties of the avian compass; the basic scheme of the radical pair mechanism; the reaction kinetics in cryptochrome; quantum coherence and entanglement in the avian compass; and the effects of noise. We believe that the quantum avian compass can play an important role in avian navigation and can also provide the foundation for a new generation of sensitive and selective magnetic-sensing nano-devices.

  8. 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.

  9. Electropolishing and chemical passivation of austenitic steel

    Directory of Open Access Journals (Sweden)

    A. Baron

    2008-12-01

    Full Text Available Purpose: The aim of the paper is investigations a dependence between the parameters of the electrochemical treatment of austenitic steel and their electrochemical behavior in Tyrod solution.Design/methodology/approach: Specimens (rode 30 mm × ø1 mm were to give in to the surface treatment – mechanically polishing, electrolytic polishing and passivation with various parameter. Electrochemical investigations concerning the corrosion resistance of austenitic steel samples were carried out by means of the potentiodynamic and electrochemical impedance spectroscopy method.Findings: The analysis of the obtained results leads to the conclusion that chemical passivation affects also the chemical composition of the passive layer of steel and changes its resistance to corrosion. Electrolytic polishing improves corrosion resistance, as can be proved by the shift of the value of the corrosion potential and break-down potential of the passive layer and the initiation of pittings.Research limitations/implications: The obtained results are the basis for the optimization of anodic passivation parameters of the austenitic steel as a metallic biomaterial. The future research should be focused on selected more suitable parameters of the electrochemical impedance spectroscopy test to better describe process on the solid/ liquid interface.Practical implications: In result of the presented investigations it has been found that the best corrosion resistance can be achieved thanks to the application of electrolytic polishing of the steel in a special bath and chemical passivation in nitric (V acid with an addition of chromic (VI acid temperature t = 60°C for one hour.Originality/value: The enormous demand for metal implants has given rise to a search for cheap materials with a good biotolerance and resistance to corrosion. Most commonly used are steel implants assigned to remain in the organism for some limited time only. It was compare two electrochemical methods

  10. Synthesis and Growth Mechanism of Carbon Filaments by Chemical Vapor Deposition without Catalyst

    Institute of Scientific and Technical Information of China (English)

    Shuhe Liu; Feng Li; Shuo Bai

    2009-01-01

    Carbon filaments with diameter from several to hundreds micrometers were synthesized by chemical vapor deposition of methane without catalyst. The morphology, microstructure and mechanical properties of the carbon filament were investigated by scanning electronic microscopy, optical microscopy, X-ray diffraction and mechanical testing. The results show that the carbon filament is inverted cone shape and grows up along the gas flow direction. The stem of it is formed of annular carbon layers arranged in a tree ring structure while the head is made up of concentrical layers. The tensile strength of the carbon filament is increased after graphitization for the restructuring and growing large of graphene. The growth mechanism of carbon filament was proposed according to the results of two series of experiments with different deposition time and intermittent deposition cycles.

  11. Effects of bioleaching on the mechanical and chemical properties of waste rocks

    Science.gov (United States)

    Yin, Sheng-Hua; Wu, Ai-Xiang; Wang, Shao-Yong; Ai, Chun-Ming

    2012-01-01

    Bioleaching processes cause dramatic changes in the mechanical and chemical properties of waste rocks, and play an important role in metal recovery and dump stability. This study focused on the characteristics of waste rocks subjected to bioleaching. A series of experiments were conducted to investigate the evolution of rock properties during the bioleaching process. Mechanical behaviors of the leached waste rocks, such as failure patterns, normal stress, shear strength, and cohesion were determined through mechanical tests. The results of SEM imaging show considerable differences in the surface morphology of leached rocks located at different parts of the dump. The mineralogical content of the leached rocks reflects the extent of dissolution and precipitation during bioleaching. The dump porosity and rock size change under the effect of dissolution, precipitation, and clay transportation. The particle size of the leached rocks decreased due to the loss of rock integrity and the conversion of dry precipitation into fine particles.

  12. Mechanical properties of chemical vapor deposited coatings for fusion reactor application

    International Nuclear Information System (INIS)

    Chemical vapor deposited coatings of TiB2, TiC and boron on graphite substrates are being developed for application as limiter materials in magnetic confinement fusion reactors. In this application severe thermal shock conditions exist and to do effective thermo-mechanical modelling of the material response it is necessary to acquire elastic moduli, fracture strength and strain to fracture data for the coatings. Four point flexure tests have been conducted from room temperature to 20000C on TiB2 and boron coated graphite with coatings in tension and compression and the mechanical properties extracted from the load-deflection data. In addition, stress relaxation tests from 500 to 11500C were performed on TiB2 and TiC coated graphite beams to assess the low levels of plastic deformation which occur in these coatings. Significant differences have been observed between the effective mechanical properties of the coatings and literature values of the bulk properties

  13. 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.

  14. Integration of large chemical kinetic mechanisms via exponential methods with Krylov approximations to Jacobian matrix functions

    KAUST Repository

    Bisetti, Fabrizio

    2012-06-01

    Recent trends in hydrocarbon fuel research indicate that the number of species and reactions in chemical kinetic mechanisms is rapidly increasing in an effort to provide predictive capabilities for fuels of practical interest. In order to cope with the computational cost associated with the time integration of stiff, large chemical systems, a novel approach is proposed. The approach combines an exponential integrator and Krylov subspace approximations to the exponential function of the Jacobian matrix. The components of the approach are described in detail and applied to the ignition of stoichiometric methane-air and iso-octane-air mixtures, here described by two widely adopted chemical kinetic mechanisms. The approach is found to be robust even at relatively large time steps and the global error displays a nominal third-order convergence. The performance of the approach is improved by utilising an adaptive algorithm for the selection of the Krylov subspace size, which guarantees an approximation to the matrix exponential within user-defined error tolerance. The Krylov projection of the Jacobian matrix onto a low-dimensional space is interpreted as a local model reduction with a well-defined error control strategy. Finally, the performance of the approach is discussed with regard to the optimal selection of the parameters governing the accuracy of its individual components. © 2012 Copyright Taylor and Francis Group, LLC.

  15. Biological effects of mechanically and chemically dispersed oil on the Icelandic scallop (Chlamys islandica).

    Science.gov (United States)

    Frantzen, Marianne; Regoli, Francesco; Ambrose, William G; Nahrgang, Jasmine; Geraudie, Perrine; Benedetti, Maura; Locke, William L; Camus, Lionel

    2016-05-01

    This study aimed to simulate conditions in which dispersant (Dasic NS) might be used to combat an oil spill in coastal sub-Arctic water of limited depth and water exchange in order to produce input data for Net Environmental Benefit Analysis (NEBA) of Arctic and sub-Arctic coastal areas. Concentration dependent differences in acute responses and long-term effects of a 48h acute exposure to dispersed oil, with and without the application of a chemical dispersant, were assessed on the Arctic filter feeding bivalve Chlamys islandica. Icelandic scallops were exposed for 48h to a range of spiked concentrations of mechanically and chemically dispersed oil. Short-term effects were assessed in terms of lysosomal membrane stability, superoxide dismutase, catalase, gluthatione S-transferases, glutathione peroxidases, glutathione reductase, glutathione, total oxyradical scavenging capacity, lipid peroxidation and peroxisomal proliferation. Post-exposure survival, growth and reproductive investment were followed for 2 months to evaluate any long-term consequence. Generally, similar effects were observed in scallops exposed to mechanically and chemically dispersed oil. Limited short-term effects were observed after 48h, suggesting that a different timing would be required for measuring the possible onset of such effects. There was a concentration dependent increase in cumulative post-exposure mortality, but long-term effects on gonadosomatic index, somatic growth/condition factor did not differ among treatments. PMID:26809079

  16. Effect of chemical treatment of Kevlar fibers on mechanical interfacial properties of composites.

    Science.gov (United States)

    Park, Soo-Jin; Seo, Min-Kang; Ma, Tae-Jun; Lee, Douk-Rae

    2002-08-01

    In this work, the effects of chemical treatment on Kevlar 29 fibers have been studied in a composite system. The surface characteristics of Kevlar 29 fibers were characterized by pH, acid-base value, X-ray photoelectron spectroscopy (XPS), and FT-IR. The mechanical interfacial properties of the final composites were studied by interlaminar shear strength (ILSS), critical stress intensity factor (K(IC)), and specific fracture energy (G(IC)). Also, impact properties of the composites were investigated in the context of differentiating between initiation and propagation energies and ductile index (DI) along with maximum force and total energy. As a result, it was found that chemical treatment with phosphoric acid solution significantly affected the degree of adhesion at interfaces between fibers and resin matrix, resulting in improved mechanical interfacial strength in the composites. This was probably due to the presence of chemical polar groups on Kevlar surfaces, leading to an increment of interfacial binding force between fibers and matrix in a composite system.

  17. Microstructures and Mechanical Properties of Laser Welding Joint of a CLAM Steel with Revised Chemical Compositions

    Science.gov (United States)

    Chen, Shuhai; Huang, Jihua; Lu, Qi; Zhao, Xingke

    2016-05-01

    To suppress the tendency to form delta ferrite in weld metal (WM) of China low activation martensitic (CLAM) steel joint, a CLAM steel with revised chemical compositions was designed. Laser welding of the CLAM steel was investigated. The microstructures of the WM and heat-affected zone were analyzed. The impact toughness of the WM was evaluated by a Charpy impact test method with three V notches. The influence of temper temperature on mechanical properties was analyzed. It was found that the delta ferrite was eliminated almost completely in laser WM of CLAM steel with revised chemical compositions which has lower tendency to form delta ferrite than original chemical compositions. The joint has higher tensile strength than the parent metal. With increasing the heat input, the impact toughness of the joint is approximatively equal with that of parent metal first and then decreases obviously. Temper treatment could effectively improve mechanical property of the joint. When the temper temperature exceeds 600 °C, the impact toughness of the joint is higher than that of the parent metal.

  18. Combined effects of crystallography, heat treatment and surface polishing on blistering in tungsten exposed to high-flux deuterium plasma

    Science.gov (United States)

    Zayachuk, Y.; Tanyeli, I.; Van Boxel, S.; Bystrov, K.; Morgan, T. W.; Roberts, S. G.

    2016-08-01

    For tungsten exposed to low-energy hydrogen-plasmas, it has been thought that grains with surface normal are most susceptible to blistering while those with surface normal are virtually impervious to it. Here, we report results showing that non-uniformity of blister distribution depends on the state of the surface due to polishing. In electrochemically polished material blisters appear on the grains with all orientations, while in mechanically polished material blister-free areas associated with particular orientations emerge. On the other hand, blistering is shown to have a strong dependence on the level of deformation within particular grains in partially recrystallized material.

  19. Research on the chemical mechanism in the polyacrylate latex modified cement system

    International Nuclear Information System (INIS)

    In this paper, the chemical mechanism in the polyacrylate latex modified cement system was investigated by Fourier transform infrared spectra (FT-IR), X-ray photoelectron spectroscopy (XPS), gel permeation chromatography (GPC) and compact pH meter. All results have shown that the chemical reactions in the polyacrylate modified system can be divided into three stages. The hydration reactions of cement can produce large amounts of Ca(OH)2 (calcium hydroxide) and lead the whole system to be alkali-rich and exothermic at the first stage. Subsequently, this environment can do great contributions to the hydrolysis of ester groups in the polyacrylate chains, resulting in the formation of carboxyl groups at the second stage. At the third stage, the final crosslinked network structure of the product was obtained by the reaction between the carboxyl groups in the polyacrylate latex chains and Ca(OH)2

  20. The Electronic Flux in Chemical Reactions. Insights on the Mechanism of the Maillard Reaction

    Science.gov (United States)

    Flores, Patricio; Gutiérrez-Oliva, Soledad; Herrera, Bárbara; Silva, Eduardo; Toro-Labbé, Alejandro

    2007-11-01

    The electronic transfer that occurs during a chemical process is analysed in term of a new concept, the electronic flux, that allows characterizing the regions along the reaction coordinate where electron transfer is actually taking place. The electron flux is quantified through the variation of the electronic chemical potential with respect to the reaction coordinate and is used, together with the reaction force, to shed light on reaction mechanism of the Schiff base formation in the Maillard reaction. By partitioning the reaction coordinate in regions in which different process might be taking place, electronic reordering associated to polarization and transfer has been identified and found to be localized at specific transition state regions where most bond forming and breaking occur.

  1. Research on the chemical mechanism in the polyacrylate latex modified cement system

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Min [The Key Laboratory of Space Applied Physics and Chemistry, Ministry of Education and Shaanxi Key Laboratory of Macromolecular Science and Technology, School of Science, Northwestern Polytechnical University, Xi' an 710072 (China); Wang, Rumin, E-mail: wangmin19@mail.nwpu.edu.cn [The Key Laboratory of Space Applied Physics and Chemistry, Ministry of Education and Shaanxi Key Laboratory of Macromolecular Science and Technology, School of Science, Northwestern Polytechnical University, Xi' an 710072 (China); Zheng, Shuirong [The Key Laboratory of Space Applied Physics and Chemistry, Ministry of Education and Shaanxi Key Laboratory of Macromolecular Science and Technology, School of Science, Northwestern Polytechnical University, Xi' an 710072 (China); Northwestern Polytechnical University–East China University of Science and Technology Combined Research Institute of New High Speed Railway Materials (China); Farhan, Shameel; Yao, Hao; Jiang, Hao [The Key Laboratory of Space Applied Physics and Chemistry, Ministry of Education and Shaanxi Key Laboratory of Macromolecular Science and Technology, School of Science, Northwestern Polytechnical University, Xi' an 710072 (China)

    2015-10-15

    In this paper, the chemical mechanism in the polyacrylate latex modified cement system was investigated by Fourier transform infrared spectra (FT-IR), X-ray photoelectron spectroscopy (XPS), gel permeation chromatography (GPC) and compact pH meter. All results have shown that the chemical reactions in the polyacrylate modified system can be divided into three stages. The hydration reactions of cement can produce large amounts of Ca(OH){sub 2} (calcium hydroxide) and lead the whole system to be alkali-rich and exothermic at the first stage. Subsequently, this environment can do great contributions to the hydrolysis of ester groups in the polyacrylate chains, resulting in the formation of carboxyl groups at the second stage. At the third stage, the final crosslinked network structure of the product was obtained by the reaction between the carboxyl groups in the polyacrylate latex chains and Ca(OH){sub 2}.

  2. Structural, Mechanical and Optical Properties of Plasma-chemical Si-C-N Films

    Directory of Open Access Journals (Sweden)

    A.O. Kozak

    2014-11-01

    Full Text Available An influence of the substrate temperature in the range of 40-400 °C on the properties of the Si-C-N films deposited by plasma enhanced chemical vapor deposition (PECVD technique using hexamethyldisilazane is analyzed. Study of the structure, chemical bonding, surface morphology, mechanical properties and energy gap of the obtained films was carried out using X-ray diffraction, infrared spectroscopy, X-ray photoelectron spectroscopy, atomic force microscopy, optical measurements and nanoindentation. It was established that all the films were X-ray amorphous and had low surface roughness. Intensive hydrogen effusion from the films takes place, when substrate temperature increases up to 400 °C, which promotes a decrease of roughness and an increase in hardness and Young modules more than twice.

  3. Evolution of mechanical properties of silicate glasses: Impact of the chemical composition and effects of irradiation

    International Nuclear Information System (INIS)

    This thesis examines: (1) how the chemical composition changes the hardness, toughness, and stress corrosion cracking behavior in model pristine and (2) how external irradiation impact these properties. It is to be incorporated in the context of the storage of nuclear waste in borosilicate glass matrix, the structural integrity of which should be assessed. Eight simplified borosilicate glasses made of 3 oxides with modulated proportions (SiO2-B2O3-Na2O (SBN) have been selected and their hardness, toughness, and stress corrosion cracking behavior have been characterized prior and after irradiation. The comparative study of the non-irradiated SBN glasses provides the role played by the chemical composition. The sodium content is found to be the key parameter: As it increases, the glass plasticity increases, leading to changes in the mechanical response to strain. Hardness (Hv) and toughness (Kc) decrease since the flow under indenter increases. The analysis of the stress corrosion behavior evidences a clear shift of the SCC curves linked also to the glass plasticity. Four of the 8 simplified SBN glass systems highlight the influence of electron, light and heavy ions irradiations on the mechanical properties. Once again, the sodium content is a key parameter. It is found to inhibit the glass modification: Glasses with high sodium content are more stable. Ions irradiations highlight the predominant role of nuclear interaction in changing the glass properties. Finally, electronic interaction induced by helium and electron irradiation does not lead to the same structural/mechanical glasses variations. (author)

  4. Postharvest Chemical, Sensorial and Physical-Mechanical Properties of Wild Apricot (Prunus armeniaca L.

    Directory of Open Access Journals (Sweden)

    Evica MRATINIĆ

    2011-11-01

    Full Text Available Some chemical, sensorial and physical-mechanical properties of 19 apricot genotypes and Hungarian Best (control such as moisture content, soluble solids content, titratable acidity ratio and their ratio, fruit and stone mass, flesh/stone ratio, fruit dimensions (length, width, thickness, arithmetic and geometric mean diameter, sphericity, surface area and aspect ratio were determined. Their application is also discussed. The highest moisture content and stone mass observed in X-1/1/04 and X-1/2/04, soluble solids content in ZO-1/03, titratable acidity in ZL-2/03, SS/TA ratio in ZL-1/03, and fruit mass and flesh/stone ratio in DL-1/1/04 genotype. The most number of genotypes have orange and deep orange skin and flesh colour, respectively, whereas sweet kernel taste was predominant in most genotypes. Regarding physical-mechanical properties, the superior fruit dimensions (length, width, thickness, arithmetic and geometric mean diameter and surface area observed in DL-1/1/04 genotype, whereas the highest sphericity and surface area observed in X-1/1/04 and X-1/2/04 genotypes. Also, the series of genotypes evaluated have better chemical, sensorial and physical-mechanical properties than Hungarian Best (control. Finally, information about these properties is very important for understanding the behaviour of the product during the postharvest operations.

  5. Synthetically chemical-electrical mechanism for controlling large scale reversible deformation of liquid metal objects

    Science.gov (United States)

    Zhang, Jie; Sheng, Lei; Liu, Jing

    2014-11-01

    Reversible deformation of a machine holds enormous promise across many scientific areas ranging from mechanical engineering to applied physics. So far, such capabilities are still hard to achieve through conventional rigid materials or depending mainly on elastomeric materials, which however own rather limited performances and require complicated manipulations. Here, we show a basic strategy which is fundamentally different from the existing ones to realize large scale reversible deformation through controlling the working materials via the synthetically chemical-electrical mechanism (SCHEME). Such activity incorporates an object of liquid metal gallium whose surface area could spread up to five times of its original size and vice versa under low energy consumption. Particularly, the alterable surface tension based on combination of chemical dissolution and electrochemical oxidation is ascribed to the reversible shape transformation, which works much more flexible than many former deformation principles through converting electrical energy into mechanical movement. A series of very unusual phenomena regarding the reversible configurational shifts are disclosed with dominant factors clarified. This study opens a generalized way to combine the liquid metal serving as shape-variable element with the SCHEME to compose functional soft machines, which implies huge potential for developing future smart robots to fulfill various complicated tasks.

  6. Chemical influence on the hydro-mechanical behaviour of high-density bentonite

    International Nuclear Information System (INIS)

    In radioactive waste disposal schemes, during the operational period of clay barriers, solute transport an d thermal gradients may alter the solute concentration of pore water. These induced changes have important consequences on hydro-mechanical properties and microstructural alterations (mineral composition and pore size distribution changes) of the clay barrier. Chemically induced changes originated by different imbibition fluids and soil mineral compositions have been a subject with a long research tradition. These researches have been mainly focused on the behaviour of reconstituted soils starting from slurry and saturated wit h saline solutions at elevated concentrations, where hydro-mechanical changes (soil compressibility and water permeability changes) are clearly detected. In contrast, available information concerning the response of high-density clays subjected to chemically induced actions with a wide range of pore solution concentrations is very limited in spite of its practical relevance to environmental geotechnics. This situation has been caused, at least in part, by the difficulties in detecting important hydro-mechanical changes when clays with low water storage capacity have been used. Nevertheless, this paper will demonstrate that even in the case of high-density fabrics, considerable changes can be observed when high-activity clays (bentonites) are imbibed with different pore fluid compositions. (authors)

  7. Polishing methods for metallic and ceramic transmission electron microscopy specimens: Revision 1

    Energy Technology Data Exchange (ETDEWEB)

    Kestel, B.J.

    1986-03-01

    In recent years, the increasing sophistication of transmission electron microscope (TEM) studies of materials has necessitated more exacting methods of specimen preparation. The present report describes improved equipment and techniques for electropolishing and chemically polishing a wide variety of specimens. Many of the specimens used in developing or improving the techniques to be described were irradiated with heavy ions such as nickel or vanadium to study radiation damage. The high cost of these specimens increased the need for reproducible methods of initial preparation postirradiation processing, and final thinning for TEM examination. A technique was also developed to salvage specimens that had previously been thinned but were unusable for various reasons. Jet polishing is, in general, the method of choice for surface polishing, sectioning, and thinning. The older beaker electropolishing method is included in this report because it is inexpensive and simple, and gives some insight into how the more recent methods were developed.

  8. Scientific Basis for a Coupled Thermal-Hydrological-Mechanical-Chemical-Biological Experimental Facility at DUSEL Homestake

    Science.gov (United States)

    Sonnenthal, E. L.; Elsworth, D.; Lowell, R. P.; Maher, K.; Mailloux, B. J.; Uzunlar, N.; Freifeld, B. M.; Keimowitz, A. R.; Wang, J. S.

    2009-12-01

    Most natural and engineered earth system processes involve strong coupling of thermal, mechanical, chemical, and sometimes biological processes in rocks that are heterogeneous at a wide range of spatial scales. One of the most pervasive processes in the Earth’s crust is that of fluids (primarily water, but also CO2, hydrocarbons, volcanic gases, etc.) flowing through fractured heated rock under stress. A preliminary design is being formulated for a large-scale subsurface experimental facility to investigate coupled Thermal-Hydrological-Mechanical-Chemical-Biological (THMCB) processes in fractured rock at depth. The experiment would be part of the proposed Deep Underground Science and Engineering Laboratory (DUSEL) in the Homestake Mine, South Dakota. Fundamental geochemical, isotopic, microbiological, laboratory THMC experiments, and numerical modeling will be used to guide the experimental design and evaluation of the time and spatial scales of the coupled THMCB processes. Although we sometimes analyze rocks and fluids for physical and chemical properties, it is difficult to create quantitative numerical models based on fundamental physics and chemistry that can capture the dynamic changes that have occurred or may yet take place. Initial conditions and history are only known roughly at best, and the boundary conditions have likely varied over time as well. Processes such as multicomponent chemical and thermal diffusion, multiphase flow, advection, and thermal expansion/contraction, are taking place simultaneously in rocks that are structurally and chemically complex—heterogeneous assemblages of mineral grains, pores, and fractures—and visually opaque. The only way to fully understand such processes is to carry out well-controlled experiments at a range of scales (grain/pore-scale to decimeter-scale) that can be interrogated and modeled. The THMCB experimental facility is also intended to be a unique laboratory for testing hypotheses regarding effects of

  9. Chemical and mechanical performance properties for various final waste forms -- PSPI scoping study

    Energy Technology Data Exchange (ETDEWEB)

    Farnsworth, R.K.; Larsen, E.D.; Sears, J.W.; Eddy, T.L.; Anderson, G.L.

    1996-09-01

    The US DOE is obtaining data on the performance properties of the various final waste forms that may be chosen as primary treatment products for the alpha-contaminated low-level and transuranic waste at the INEL`s Transuranic Storage Area. This report collects and compares selected properties that are key indicators of mechanical and chemical durability for Portland cement concrete, concrete formed under elevated temperature and pressure, sulfur polymer cement, borosilicate glass, and various forms of alumino-silicate glass, including in situ vitrification glass and various compositions of iron-enriched basalt (IEB) and iron-enriched basalt IV (IEB4). Compressive strength and impact resistance properties were used as performance indicators in comparative evaluation of the mechanical durability of each waste form, while various leachability data were used in comparative evaluation of each waste form`s chemical durability. The vitrified waste forms were generally more durable than the non-vitrified waste forms, with the iron-enriched alumino-silicate glasses and glass/ceramics exhibiting the most favorable chemical and mechanical durabilities. It appears that the addition of zirconia and titania to IEB (forming IEB4) increases the leach resistance of the lanthanides. The large compositional ranges for IEB and IEB4 more easily accommodate the compositions of the waste stored at the INEL than does the composition of borosilicate glass. It appears, however, that the large potential variation in IEB and IEB4 compositions resulting from differing waste feed compositions can impact waste form durability. Further work is needed to determine the range of waste stream feed compositions and rates of waste form cooling that will result in acceptable and optimized IEB or IEB4 waste form performance. 43 refs.

  10. Synthesis, mechanical, thermal and chemical properties of polyurethanes based on cardanol

    Indian Academy of Sciences (India)

    C V Mythili; A Malar Retna; S Gopalakrishnan

    2004-06-01

    Cardanol, an excellent monomer for polymer production, has been isolated from CNSL and allowed to react with formaldehyde in a particular mole ratio in the presence of glutaric acid catalyst to give high-ortho novolac resin. Such characterized polyol has been condensed with diphenylmethane diisocyanate to produce rigid polyurethane. A commercially available polyol, polypropylene glycol-2000 (PPG-2000), has also been condensed with diphenylmethane diisocyanate and polyol to produce tough polyurethane. These polyurethanes were characterized with respect to their resistance to chemical reagents and mechanical properties such as tensile strength, percentage elongation, tear strength and hardness. Differential thermal analysis (DTA) and thermo-gravimetric analysis (TGA) were undertaken for thermal characterization.

  11. Different sensing mechanisms in single wire and mat carbon nanotubes chemical sensors

    CERN Document Server

    Neumann, P L; Dobrik, G; Kertész, K; Horváth, E; Lukács, I E; Biró, L P; Horváth, Z E

    2014-01-01

    Chemical sensing properties of single wire and mat form sensor structures fabricated from the same carbon nanotube (CNT) materials have been compared. Sensing properties of CNT sensors were evaluated upon electrical response in the presence of five vapours as acetone, acetic acid, ethanol, toluene, and water. Diverse behaviour of single wire CNT sensors was found, while the mat structures showed similar response for all the applied vapours. This indicates that the sensing mechanism of random CNT networks cannot be interpreted as a simple summation of the constituting individual CNT effects, but is associated to another robust phenomenon, localized presumably at CNT-CNT junctions, must be supposed.

  12. Load transfer and mechanical properties of chemically reduced graphene reinforcements in polymer composites

    International Nuclear Information System (INIS)

    We report load transfer and mechanical properties of chemically derived single layer graphene (SLG) as reinforcements in poly (dimethyl) siloxane (PDMS) composites. Shear mixing reduced graphene sheets in polymers resulted in a marked decrease of the 2D band intensity due to doping and functionalization. Raman G mode shifts of 11.2 cm−1/% strain in compression and 4.2 cm−1/% strain in tension are reported. Increases in elastic modulus of PDMS by ∼42%, toughness by ∼39%, damping capability by ∼673%, and strain energy density of ∼43% by the addition of 1 wt% SLG in PDMS are reported. (paper)

  13. CHEMICALS

    CERN Multimedia

    Medical Service

    2002-01-01

    It is reminded that all persons who use chemicals must inform CERN's Chemistry Service (TIS-GS-GC) and the CERN Medical Service (TIS-ME). Information concerning their toxicity or other hazards as well as the necessary individual and collective protection measures will be provided by these two services. Users must be in possession of a material safety data sheet (MSDS) for each chemical used. These can be obtained by one of several means : the manufacturer of the chemical (legally obliged to supply an MSDS for each chemical delivered) ; CERN's Chemistry Service of the General Safety Group of TIS ; for chemicals and gases available in the CERN Stores the MSDS has been made available via EDH either in pdf format or else via a link to the supplier's web site. Training courses in chemical safety are available for registration via HR-TD. CERN Medical Service : TIS-ME :73186 or service.medical@cern.ch Chemistry Service : TIS-GS-GC : 78546

  14. Polished sapphire for ultracold-neutron guides

    Energy Technology Data Exchange (ETDEWEB)

    Nesvizhevsky, V.V. [Institut Laue-Langevin, 6 rue Jules Horowitz, 38042 Grenoble (France)]. E-mail: nesvizhevsky@ill.fr

    2006-02-15

    We show that polished sapphire allows one to efficiently reflect ultracold neutrons (UCN) at specular trajectories. The probability of specular UCN reflection at sapphire surface under typical experimental conditions was measured to be at least 99.8%. That could provide nearly loss-free transport of UCN between a source and an experimental installation at a distance of some 10 m. Polished sapphire can be used for specular neutron guides at steady and pulsed UCN sources. It can also be used in experimental installations, in particular, for building compact gravitational spectrometers and for study of the resonance transitions between neutron quantum states in the gravitational field.

  15. POLISH-RUSSIAN COOPERATION OF POMORSKIE PROVINCE

    Directory of Open Access Journals (Sweden)

    Christina GOMULKA

    2015-01-01

    Full Text Available Polish-Russian Cooperation of Pomorskie Province commenced in 1999 and was based on the intergovernmental agreements. The new agreement, executed between the authorities of the Pomeranian Province and Kaliningrad Oblast in 2002, provided for cooperation in many areas. The contacts between the partners were dominated by economic cooperation. The Polish–Russian cooperation stopped with Polish accession to the Schengen zone. Cooperation resumed when in 2011 and agreement on small cross-border traffic was signed and then ratified in 2012. 

  16. Mechanical and microstructural/chemical degradation of coating and substrate in gas turbine blade

    Energy Technology Data Exchange (ETDEWEB)

    Sugita, Y.; Ito, M. [Chubu Electric Power Co. Inc., Nagoya (Japan); Sakurai, S. [Hitachi Ltd., Ibaraki (Japan). Hitachi Research Lab.; Gold, C.R.; Bloomer, T.E.; Kameda, J. [Iowa State Univ. of Science and Technology, Ames, IA (United States). Center for Advanced Technology Development

    1995-12-31

    The mechanical property degradation (295--1223 K) and microstructural/chemical evolution of CoNiCrAlY coatings and superalloy (Rene 80) substrates in gas turbine blades operated in- service have been studied using a small punch (SP) testing technique and scanning Auger microprobe. In SP tests, coating cracks continuously and discretely propagated at 295 K and higher temperatures, respectively. The ductile-brittle transition temperature of the coatings was increased during long time exposure of gas turbine blades to oxidizing environments while that of the substrate did not change. The low cycle fatigue life of the coatings at 295 K was also reduced in-service. Oxidation and sulfur segregation near the coating surface were found to be major causes of the mechanical degradation of the coatings.

  17. Detailed chemical kinetic mechanism for the oxidation of biodiesel fuels blend surrogate.

    Energy Technology Data Exchange (ETDEWEB)

    Herbinet, O; Pitz, W J; Westbrook, C K

    2009-07-21

    Detailed chemical kinetic mechanisms were developed and used to study the oxidation of two large unsaturated esters: methyl-5-decenoate and methyl-9-decenoate. These models were built from a previous methyl decanoate mechanism and were compared with rapeseed oil methyl esters oxidation experiments in a jet stirred reactor. A comparative study of the reactivity of these three oxygenated compounds was performed and the differences in the distribution of the products of the reaction were highlighted showing the influence of the presence and the position of a double bond in the chain. Blend surrogates, containing methyl decanoate, methyl-5-decenoate, methyl-9-decenoate and n-alkanes, were tested against rapeseed oil methyl esters and methyl palmitate/n-decane experiments. These surrogate models are realistic kinetic tools allowing the study of the combustion of biodiesel fuels in diesel and homogeneous charge compression ignition engines.

  18. Recent Developments in the Theory of Mechanisms in Radiation Chemical Processes

    International Nuclear Information System (INIS)

    Recent developments in the mechanisms of radiation-initiated chemical reactions are reviewed. The role of ion molecule processes is reviewed, with particular reference to the radiation chemistry of methane. In this system, the existence of reactions of excited molecules, in addition to ionic processes is deduced. It is shown that, in the radiolysis of methane, unsaturated hydrocarbons play a considerable part in the mechanism of reaction. Developments in ionic polymerization and also polymerization under heterogenous conditions are reviewed. The importance of reactant purity, and also cleanliness of reaction vessels is discussed. The effect of an applied external potential in solid state polymerization is briefly reviewed. The importance of free-radical processes to radiation chemists is considered in the light of the Dow process for the production of ethyl bromide. (author)

  19. Stability for a novel low-pH alkaline slurry during the copper chemical mechanical planarization

    International Nuclear Information System (INIS)

    The stability of a novel low-pH alkaline slurry (marked as slurry A, pH = 8.5) for copper chemical mechanical planarization was investigated in this paper. First of all, the stability mechanism of the alkaline slurry was studied. Then many parameters have been tested for researching the stability of the slurry through comparing with a traditional alkaline slurry (marked as slurry B, pH = 9.5), such as the pH value, particle size and zeta potential. Apart from this, the stability of the copper removal rate, dishing, erosion and surface roughness were also studied. All the results show that the stability of the novel low-pH alkaline slurry is better than the traditional alkaline slurry. The working-life of the novel low-pH alkaline slurry reaches 48 h. (semiconductor technology)

  20. Computational organic chemistry: bridging theory and experiment in establishing the mechanisms of chemical reactions.

    Science.gov (United States)

    Cheng, Gui-Juan; Zhang, Xinhao; Chung, Lung Wa; Xu, Liping; Wu, Yun-Dong

    2015-02-11

    Understanding the mechanisms of chemical reactions, especially catalysis, has been an important and active area of computational organic chemistry, and close collaborations between experimentalists and theorists represent a growing trend. This Perspective provides examples of such productive collaborations. The understanding of various reaction mechanisms and the insight gained from these studies are emphasized. The applications of various experimental techniques in elucidation of reaction details as well as the development of various computational techniques to meet the demand of emerging synthetic methods, e.g., C-H activation, organocatalysis, and single electron transfer, are presented along with some conventional developments of mechanistic aspects. Examples of applications are selected to demonstrate the advantages and limitations of these techniques. Some challenges in the mechanistic studies and predictions of reactions are also analyzed.

  1. Changes in mechanical and chemical wood properties by electron beam irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Schnabel, Thomas, E-mail: thomas.schnabel@fh-salzburg.ac.at [Salzburg University of Applied Sciences, Department of Forest Products Technology and Wood Constructions, Marktstraße 136a, 5431 Kuchl (Austria); Huber, Hermann [Salzburg University of Applied Sciences, Department of Forest Products Technology and Wood Constructions, Marktstraße 136a, 5431 Kuchl (Austria); Grünewald, Tilman A. [BOKU University of Natural Resources and Life Sciences, Institute of Physics and Materials Science, Peter Jordan Straße 82, 1190 Vienna (Austria); Petutschnigg, Alexander [Salzburg University of Applied Sciences, Department of Forest Products Technology and Wood Constructions, Marktstraße 136a, 5431 Kuchl (Austria); BOKU University of Natural Resources and Life Sciences, Konrad Lorenzstraße 24, 3430 Tulln (Austria)

    2015-03-30

    Highlights: • Changes in wood due to electron beam irradiations (EBI) were evaluated. • Wood components undergo different altering mechanisms due to the irradiation. • Chemical reactions in wood lead to better surface hardness of low irradiated wood. - Abstract: This study deals with the influence of various electron beam irradiation (EBI) dosages on the Brinell hardness of Norway spruce. The results of the hardness measurements and the FT-IR spectroscopic analysis show different effects of the EBI at dosages of 25, 50, 100 and 200 kGy. It was assumed that the lignin and carbohydrates undergo different altering mechanisms due to the EBI treatment. New cleavage products and condensation reactions of lignin and carbohydrates lead to better surface hardness of low irradiated wood samples. These results provide a useful basis for further investigations on the changes in wood chemistry and material properties due to electron beam irradiations.

  2. Chemical bath deposition of CdS thin films: An approach to the chemical mechanism through study of the film microstructure

    Energy Technology Data Exchange (ETDEWEB)

    Dona, J.M.; Herrero, J. [CIEMAT, Madrid (Spain). Inst. de Energias Renovables

    1997-11-01

    Many papers have been published lately on chemical bath deposition of CdS (CBD-CdS) thin films and related materials due to the promising results obtained using CBD-CdS for the fabrication of thin-film solar cells. In spite of this little of the research proposes a realistic chemical mechanism for the deposition process based on the determination of kinetic parameters. In this paper the authors present an exhaustive study of the CBD-CdS kinetic from which they propose a new chemical mechanism which agrees with the kinetic parameters determined supported by heterogeneous catalysis concepts. Simultaneously, the dependence of the deposited film structure on the kinetic variables is studied and the results obtained corroborate the proposed mechanism. These studies have allowed the authors to establish a standard set of conditions for the fabrication of homogeneous and continuous very thin CdS films.

  3. 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.

  4. Physical-chemical principles of corrosion inhibitors for metals and metallic alloys and the inhibition mechanisms

    International Nuclear Information System (INIS)

    The usage of corrosion inhibitors is one of the most important cheapest, easy and efficient methods for controlling the process of the metallic corrosion. This method relies on adding one or more chemical substance at certain concentration to the corroding mediums for retarding of the corrosion process of surfaces corrosion of the metals and alloys. The corrosion inhibitors are considered as a first line of defense against the corrosion process in the petroleum, chemical industrial plants and in the water treating stations. The inhibitor is a complicated subject and applied successfully only in special cases. For example some inhibitors may be effective for one metal or more. The optimum efficiency of each inhibitor can be achieved at certain conditions (such as concentration, temperature and ph). The effective inhibitor for a metal (in the special conditions) may be a corrosive media for another metal (or in other conditions). There are a lot of inhibitors used for preventing process of the corrosion but there is no classification of the inhibitors until now. Several attempts for the classification of inhibitors in accordance to their chemical nature (organic, inorganic, biological and green), to their properties (an oxidizer or inoxidizer) or to their application field (cleaning, or peeling). On the other hand, the incorrect utilization of inhibitors could lead to an increase in the corrosion rate and/or in the hydrogenous creep of the metals and alloys. The inhibition mechanism of the inorganic inhibitors depends on the forming of protective layers on metals surface which retard the corrosion process. organic inhibitors mechanism depends on the surfactant's group adsorption like N, S, COOH, NH2 SH on the metal surface forming micelle which act as physical barrier for protecting the surface against the corrosive media or forming a stable surface complexes. The efficiency of the inhibitors performance can be measured by extent of the adhesion of their molecules on

  5. An optimized chemical kinetic mechanism for HCCI combustion of PRFs using multi-zone model and genetic algorithm

    International Nuclear Information System (INIS)

    Highlights: • A new chemical kinetic mechanism for PRFs HCCI combustion is developed. • New mechanism optimization is performed using genetic algorithm and multi-zone model. • Engine-related combustion and performance parameters are predicted accurately. • Engine unburned HC and CO emissions are predicted by the model properly. - Abstract: Development of comprehensive chemical kinetic mechanisms is required for HCCI combustion and emissions prediction to be used in engine development. The main purpose of this study is development of a new chemical kinetic mechanism for primary reference fuels (PRFs) HCCI combustion, which can be applied to combustion models to predict in-cylinder pressure and exhaust CO and UHC emissions, accurately. Hence, a multi-zone model is developed for HCCI engine simulation. Two semi-detailed chemical kinetic mechanisms those are suitable for premixed combustion are used for n-heptane and iso-octane HCCI combustion simulation. The iso-octane mechanism contains 84 species and 484 reactions and the n-heptane mechanism contains 57 species and 296 reactions. A simple interaction between iso-octane and n-heptane is considered in new mechanism. The multi-zone model is validated using experimental data for pure n-heptane and iso-octane. A new mechanism is prepared by combination of these two mechanisms for n-heptane and iso-octane blended fuel, which includes 101 species and 594 reactions. New mechanism optimization is performed using genetic algorithm and multi-zone model. Mechanism contains low temperature heat release region, which decreases with increasing octane number. The results showed that the optimized chemical kinetic mechanism is capable of predicting engine-related combustion and performance parameters. Also after implementing the optimized mechanism, engine unburned HC and CO emissions predicted by the model are in good agreement with the corresponding experimental data

  6. Mechanical and chemical behavior of intergranular fluids in nonhydrostatically stressed rocks at low temperature

    Institute of Scientific and Technical Information of China (English)

    刘亮明; 彭省临

    2001-01-01

    Intergranular fluids within the nonhydrostatically stressed solids are a sort of important fluids in the crust. Research on the mechanical and chemical behavior of the intergranular fluids in nonhydrostatically stressed rocks at low temperature is a key for understanding deformation and syntectonic geochemical processes in mid to shallow crust. Theoretically, it is suggested that the fluid film sandwiched between solid grains is one of the main states of intergranular fluids in the nonhydrostatically stressed solids. Their superthin thickness makes the fluid films have the mechanical and chemical behavior very different from the common fluids. Because of hydration force, double-layer repulsive force or osmotic pressure due to double-layer, the fluid films can transmit nonhydrostatic stress. The solid minerals-intergranular fluids interaction and mass transfer by intergranular fluids is stress-related, because the stress in solid minerals can enhance the free energy of solid matter on the interfaces. The thermodynamic and kinetic equations for the simple case of stress induced processes are derived.

  7. SYNERGISTIC EFFECTS BETWEEN BIRCH CHEMICAL MECHANICAL PULPS AND ASPEN BLEACHED KRAFT PULP

    Institute of Scientific and Technical Information of China (English)

    Eric C. Xu; Yajun Zhou

    2004-01-01

    In this investigation, two different grades of birch chemical mechanical (P-RC APMP) pulps and aspen market bleached kraft pulp were compared by low consistency refining of the pulps separately and in different combinations. In addition, the separately refined pulps were also combined to compare with the pulps from the co-refined pulp blend. The results showed that in both cases there were synergistic effects between the two types of pulps: adding the birch P-RC APMP pulp to the aspen kraft pulp improved pulp properties, and the resultant pulp blends had a higher fiber bonding strength (tensile and tensile energy absorption) than the sum of weighted contributions from the individual components. Understanding this synergistic effect between chemical mechanical (P-RC APMP) and kraft pulps can help to improve their applications and performances in various papermaking processes.The results also showed that introducing, at least up to certain percentage of, the birch P-RC APMP pulp into the aspen bleached kraft pulp not only improves optical and bulk properties, but also maintains or improves tensile strength, even though the P-RC APMP pulp used has lower tensile than the kraft pulp.

  8. SYNERGISTIC EFFECTS BETWEEN BIRCH CHEMICAL MECHANICAL PULPS AND ASPEN BLEACHED KRAFT PULP

    Institute of Scientific and Technical Information of China (English)

    EricC.Xu; YajunZhou

    2004-01-01

    In this investigation, two different grades of birch chemical mechanical (P-RC APMP) pulps and aspen market bleached kraft pulp were compared by low consistency refining of the pulps separately and in different combinations. In addition, the separately refined pulps were also combined to compare with the pulps from the co-refined pulp blend. The results showed that in both cases there were synergistic effects between the two types of pulps: adding the birch P-RC APMP pulp to the aspen kraft pulp improved pulp properties, and the resultant pulp blends had a higher fiber bonding strength (tensile and tensile energy absorption) than the sum of weighted contributions from the individual components. Understanding this synergistic effect between chemical mechanical (P-RC APMP) and kraft pulps can help to improve their applications and performances in various papermaking processes. The results also showed that introducing, at least up to certain percentage of, the birch P-RC APMP pulp into the aspen bleached kraft pulp not only improves optical and bulk properties, but also maintains or improves tensile strength, even though the P-RC APMP pulp used has lower tensile than the kraft pulp.

  9. Modelling the Tox21 10 K chemical profiles for in vivo toxicity prediction and mechanism characterization.

    Science.gov (United States)

    Huang, Ruili; Xia, Menghang; Sakamuru, Srilatha; Zhao, Jinghua; Shahane, Sampada A; Attene-Ramos, Matias; Zhao, Tongan; Austin, Christopher P; Simeonov, Anton

    2016-01-26

    Target-specific, mechanism-oriented in vitro assays post a promising alternative to traditional animal toxicology studies. Here we report the first comprehensive analysis of the Tox21 effort, a large-scale in vitro toxicity screening of chemicals. We test ∼ 10,000 chemicals in triplicates at 15 concentrations against a panel of nuclear receptor and stress response pathway assays, producing more than 50 million data points. Compound clustering by structure similarity and activity profile similarity across the assays reveals structure-activity relationships that are useful for the generation of mechanistic hypotheses. We apply structural information and activity data to build predictive models for 72 in vivo toxicity end points using a cluster-based approach. Models based on in vitro assay data perform better in predicting human toxicity end points than animal toxicity, while a combination of structural and activity data results in better models than using structure or activity data alone. Our results suggest that in vitro activity profiles can be applied as signatures of compound mechanism of toxicity and used in prioritization for more in-depth toxicological testing.

  10. Statistical analysis of crystallization database links protein physico-chemical features with crystallization mechanisms.

    Directory of Open Access Journals (Sweden)

    Diana Fusco

    Full Text Available X-ray crystallography is the predominant method for obtaining atomic-scale information about biological macromolecules. Despite the success of the technique, obtaining well diffracting crystals still critically limits going from protein to structure. In practice, the crystallization process proceeds through knowledge-informed empiricism. Better physico-chemical understanding remains elusive because of the large number of variables involved, hence little guidance is available to systematically identify solution conditions that promote crystallization. To help determine relationships between macromolecular properties and their crystallization propensity, we have trained statistical models on samples for 182 proteins supplied by the Northeast Structural Genomics consortium. Gaussian processes, which capture trends beyond the reach of linear statistical models, distinguish between two main physico-chemical mechanisms driving crystallization. One is characterized by low levels of side chain entropy and has been extensively reported in the literature. The other identifies specific electrostatic interactions not previously described in the crystallization context. Because evidence for two distinct mechanisms can be gleaned both from crystal contacts and from solution conditions leading to successful crystallization, the model offers future avenues for optimizing crystallization screens based on partial structural information. The availability of crystallization data coupled with structural outcomes analyzed through state-of-the-art statistical models may thus guide macromolecular crystallization toward a more rational basis.

  11. Time Evolution of Thermo-Mechanically and Chemically Coupled Magma Chambers

    Science.gov (United States)

    Ozimek, C.; Karlstrom, L.; Erickson, B. A.

    2015-12-01

    Complexity in the volcanic eruption cycle reflects time variation both of magma inputs to the crustal plumbing system and of crustal melt storage zones (magma chambers). These data include timing and volumes of eruptions, as well as erupted compositions. Thus models must take into account the coupled nature of physical attributes. Here we combine a thermo-mechanical model for magma chamber growth and pressurization with a chemical model for evolving chamber compositions, in the limit of rapid mixing, to study controls on eruption cycles and compositions through time. We solve for the mechanical evolution of a 1D magma chamber containing melt, crystals and bubbles, in a thermally evolving and viscoelastic crust. This pressure and temperature evolution constrains the input values of a chemical box model (Lee et al., 2013) that accounts for recharge, eruption, assimilation and fractional crystallization (REAFC) within the chamber. We plan to study the influence of melt supply, input composition, and chamber depth eruptive fluxes and compositions. Ultimately we will explore multiple chambers coupled by elastic-walled dikes. We expect that this framework will facilitate self-consistent inversion of long-term eruptive histories in terms of magma transport physics. Lee, C.-T. A., Lee, T.-C., Wu, C.-T., 2013. Modeling the compositional evolution of recharging, evacuating, and fractionating (REFC) magma chambers: Implications for differentiationof arc magmas. Geochemica Cosmochimica Acta, http://dx.doi.org/10.1016/j.gca.2013.08.009.

  12. Nanoporous framework materials interfaced with mechanical sensors for highly-sensitive chemical sensing.

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Jin-Hwan; Skinner, Jack L.; Houk, Ronald J. T.; Fischer, Roland A.; Robinson, Alex Lockwood; Allendorf, Mark D.; Yusenko, Kirill; Meilikhov, Mikhail; Hesketh, Peter J.; Venkatasubramanian, Anandram; Thornberg, Steven Michael

    2010-04-01

    We will describe how novel nanoporous framework materials (NFM) such as metal-organic frameworks (MOFs) can be interfaced with common mechanical sensors, such as surface acoustic wave (SAW), microcantilever array, and quartz crystal microbalance (QCM) devices, and subsequently be used to provide selectivity and sensitivity to a broad range of analytes including explosives, nerve agents, and volatile organic compounds (VOCs). NFM are highly ordered, crystalline materials with considerable synthetic flexibility resulting from the presence of both organic and inorganic components within their structure. Chemical detection using micro-electro-mechanical-systems (MEMS) devices (i.e. SAWs, microcantilevers) requires the use of recognition layers to impart selectivity. Unlike traditional organic polymers, which are dense, the nanoporosity and ultrahigh surface areas of NFM allow for greater analyte uptake and enhance transport into and out of the sensing layer. This enhancement over traditional coatings leads to improved response times and greater sensitivity, while their ordered structure allows chemical tuning to impart selectivity. We describe here experiments and modeling aimed at creating NFM layers tailored to the detection of water vapor, explosives, CWMD, and volatile organic compound (VOCs), and their integration with the surfaces of MEMS devices. Molecular simulation shows that a high degree of chemical selectivity is feasible. For example, a suite of MOFs can select for strongly interacting organics (explosives, CWMD) vs. lighter volatile organics at trace concentrations. At higher gas pressures, the CWMD are deselected in favor of the volatile organics. We will also demonstrate the integration of various NFM on the surface of microcantiliver arrays, QCM crystals, and SAW devices, and describe new synthetic methods developed to improve the quality of NFM coatings. Finally, MOF-coated MEMS devices show how temperature changes can be tuned to improve response

  13. Effects of Mechanical and Chemical Pretreatments of Zirconia or Fiber Posts on Resin Cement Bonding.

    Directory of Open Access Journals (Sweden)

    Rui Li

    Full Text Available The bonding strength between resin cement and posts is important for post and core restorations. An important method of improving the bonding strength is the use of various surface pretreatments of the post. In this study, the surfaces of zirconia (fiber posts were treated by mechanical and/or chemical methods such as sandblasting and silanization. The bonding strength between the zirconia (fiber post and the resin cement was measured by a push-out method after thermocycling based on the adhesion to Panavia F 2.0 resin cement. The zirconia and fiber posts exhibited different bonding strengths after sandblasting and/or silanization because of the different strengths and chemical structures. The zirconia post showed a high bonding strength of up to 17.1 MPa after a combined treatment of sandblasting and silanization because of the rough surface and covalent bonds at the interface. This effect was also enhanced by using 1,2-bis(trimethoxysilylethane for the formation of a flexible layer at the interface. In contrast, a high bonding strength of 13.9 MPa was obtained for the fiber post treated by silane agents because the sandblasting treatment resulted in damage to the fiber post, as observed by scanning electron microscopy. The results indicated that the improvement in the bonding strength between the post and the resin cement could be controlled by different chemical and/or mechanical treatments. Enhanced bonding strength depended on covalent bonding and the surface roughness. A zirconia post with high bonding strength could potentially be used for the restoration of teeth in the future.

  14. Effects of Mechanical and Chemical Pretreatments of Zirconia or Fiber Posts on Resin Cement Bonding

    Science.gov (United States)

    Li, Rui; Zhou, Hui; Wei, Wei; Wang, Chen; Sun, Ying Chun; Gao, Ping

    2015-01-01

    The bonding strength between resin cement and posts is important for post and core restorations. An important method of improving the bonding strength is the use of various surface pretreatments of the post. In this study, the surfaces of zirconia (fiber) posts were treated by mechanical and/or chemical methods such as sandblasting and silanization. The bonding strength between the zirconia (fiber) post and the resin cement was measured by a push-out method after thermocycling based on the adhesion to Panavia F 2.0 resin cement. The zirconia and fiber posts exhibited different bonding strengths after sandblasting and/or silanization because of the different strengths and chemical structures. The zirconia post showed a high bonding strength of up to 17.1 MPa after a combined treatment of sandblasting and silanization because of the rough surface and covalent bonds at the interface. This effect was also enhanced by using 1,2-bis(trimethoxysilyl)ethane for the formation of a flexible layer at the interface. In contrast, a high bonding strength of 13.9 MPa was obtained for the fiber post treated by silane agents because the sandblasting treatment resulted in damage to the fiber post, as observed by scanning electron microscopy. The results indicated that the improvement in the bonding strength between the post and the resin cement could be controlled by different chemical and/or mechanical treatments. Enhanced bonding strength depended on covalent bonding and the surface roughness. A zirconia post with high bonding strength could potentially be used for the restoration of teeth in the future. PMID:26066349

  15. Determination of the effective mechanism of chemically stimulated diffusion in semiconductors at their interaction with an atomic hydrogen

    International Nuclear Information System (INIS)

    Paper is devoted to calculate coefficients of chemically stimulated diffusion (CSD) of some impurities in near-the-surface layers of germanium and gallium arsenide following well-known mechanisms to determine governing mechanism of CSD depending on type of diffusing impurity and conditions to carry out experiment. Calculation results of CSD coefficients following the mentioned mechanisms for copper in germanium showed that their efficiency was rather unimpressive in contrast to CSD mechanisms associated with energy transfer to crystal atomic subsystem

  16. Effects of chemical alteration on fracture mechanical properties in hydrothermal systems

    Science.gov (United States)

    Callahan, O. A.; Eichhubl, P.; Olson, J. E.

    2015-12-01

    Fault and fracture networks often control the distribution of fluids and heat in hydrothermal and epithermal systems, and in related geothermal and mineral resources. Additional chemical influences on conduit evolution are well documented, with dissolution and precipitation of mineral species potentially changing the permeability of fault-facture networks. Less well understood are the impacts of chemical alteration on the mechanical properties governing fracture growth and fracture network geometry. We use double-torsion (DT) load relaxation tests under ambient air conditions to measure the mode-I fracture toughness (KIC) and subcritical fracture growth index (SCI) of variably altered rock samples obtained from outcrop in Dixie Valley, NV. Samples from southern Dixie Valley include 1) weakly altered granite, characterized by minor sericite in plagioclase, albitization and vacuolization of feldspars, and incomplete replacement of biotite with chlorite, and 2) granite from an area of locally intense propylitic alteration with chlorite-calcite-hematite-epidote assemblages. We also evaluated samples of completely silicified gabbro obtained from the Dixie Comstock epithermal gold deposit. In the weakly altered granite KIC and SCI are 1.3 ±0.2 MPam1/2 (n=8) and 59 ±25 (n=29), respectively. In the propylitic assemblage KIC is reduced to 0.6 ±0.1 MPam1/2 (n=11), and the SCI increased to 75 ±36 (n = 33). In both cases, the altered materials have lower fracture toughness and higher SCI than is reported for common geomechanical standards such as Westerly Granite (KIC ~1.7 MPam1/2; SCI ~48). Preliminary analysis of the silicified gabbro shows a significant increase in fracture toughness, 3.6 ±0.4 MPam1/2 (n=2), and SCI, 102 ±45 (n=19), compared to published values for gabbro (2.9 MPam1/2 and SCI = 32). These results suggest that mineralogical and textural changes associated with different alteration assemblages may result in spatially variable rates of fracture

  17. 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...

  18. 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 r...

  19. Polish Complementary Schools in Iceland and England

    Science.gov (United States)

    Zielinska, Malgorzata; Kowzan, Piotr; Ragnarsdóttir, Hanna

    2014-01-01

    Since 2004, the opening of labour markets has spurred a considerable number of Poles to emigrate e.g. to Iceland and England. Families with school age children have had the challenge of adapting to foreign environments and school systems. Polish complementary schools have played an important, albeit ambivalent, role in this process. Through focus…

  20. 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…

  1. Freeform grinding and polishing with PROSurf

    Science.gov (United States)

    Wolfs, Franciscus; Fess, Edward; DeFisher, Scott; Torres, Josh; Ross, James

    2015-10-01

    Recently, the desire to use freeform optics has been increasing, including shapes such as torics and anamorphic aspheres. Freeform optics can be used to expand capabilities of optical systems. They can compensate for limitations in rotationally symmetric optics. These same traits that give freeform optics the ability to improve optical systems also makes them more challenging to manufacture. This holds true for grinding, polishing, and metrology. As freeform optics become more prevalent in the industry, tolerances will become more stringent, requiring deterministic manufacturing processes. To generate freeforms, it is crucial to have control over all aspects of the process. Controlling the surface definition is important for achieving a better surface finish during processing. Metrology will be required to adjust tool paths at various stages in manufacturing. During grinding, metrology will be used to adjust tool positions relative to the nominal tool path to compensate for repeatable machine and tooling error. For polishing, metrology will be used to deterministically adjust dwell relative to the amount of the error in different surface locations, allowing for convergence towards the desired surface at a uniform rate. OptiPro has developed PROSurf, a CAM software package for creating freeform tool paths and applying metrology-based corrections. The software can be used for both grinding and polishing freeform optics. The software has flexibility to allow for different methods of modelling the surface: mathematical equations, solid models, and point clouds. The software is designed to make it easier to manufacture and polish complex freeform optics.

  2. Fluid jet polishing of optical surfaces

    NARCIS (Netherlands)

    Fähnle, O.W.; Brug, H. van; Frankena, H.J.

    1998-01-01

    We present a new finishing process that is capable of locally shaping and polishing optical surfaces of complex shapes. A fluid jet system is used to guide a premixed slurry at pressures less than 6 bars to the optical surface. We used a slurry comprising water and 10% #800 SiC abrasives (21.8 μm to

  3. New Environmental Practices in Polish Production Firms

    DEFF Research Database (Denmark)

    Kræmer, Trine Pipi

    2002-01-01

    Based on five case studies in Poland, the paper discusses, how a specific environmental policy influences the firms? industrial environmental practices. The study illustrates, how the Polish environmental policy, dominated by environmental charges on emissions, is extremely effective in improving...... the environmental state, but at the same time seems to direct the firms towards end-of-pipe solutions and a retrospective environmental strategy....

  4. Information Systems in the Polish Payment System

    OpenAIRE

    Murowaniecki, Łukasz; Woźniacki, Konrad

    2007-01-01

    The paper focuses on computerised information systems responsible for payment information exchange in Polish payment system. Firstly some terms, connected with the topic of funds transfer system, are ordered. Then, relying on the taxonomy, the paper presents a comprehensive view of domestic payment system.

  5. Polish Youth: A Dychotomic World of Values.

    Science.gov (United States)

    Bodnar, Artur; Zelichowski, Ryszard

    Research results show a skepticism among Polish youth concerning the possibility of implementing the accepted socialist values in political practice and denote a steady erosion of socialism's image. Youth organizations are many and varied, but it appears that most join because of the opportunity to meet friends, not because of political…

  6. 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.

  7. Contemporary Contrastive Studies of Polish, Bulgarian and Russian Neologisms versus Language Corpora

    Directory of Open Access Journals (Sweden)

    Joanna Satoła-Staśkowiak

    2015-06-01

    Full Text Available Contemporary Contrastive Studies of Polish, Bulgarian and Russian Neologisms versus Language CorporaIn the field of Slavonic linguistics contrastive studies of neologisms occupy little place, the newest words are insufficiently described and classified. The aim of this article is to draw attention to the need for contrastive description of the newest lexis and checking exclusively one of many possibilities of obtaining Polish, Bulgarian and Russian neologisms. Language corpora, as this possibility is in question, are not the only source from which the author obtains her research material, yet a growing interest in corpora has inspired her to also use this method. The author wants to show the reader to what degree language corpora can help in building the thesaurus of Polish, Bulgarian and Russian neologisms. Making an attempt to confront a collection of neologisms of contemporary Polish, Bulgarian and Russian language, the author points out the need to standardize the description (identical for each of the analysed languages, which she intends to propose in another publications on neologisms in Polish, Bulgarian and Russian language. The application of contrastive method to three different but related languages from the Slavonic group will help, in her opinion, to discover more mechanisms of new words coming into existence and examine the newest derivative processes and their productivity.

  8. Study of the Contact Force in Free-form Surfaces Compliant EDM Polishing by Robot

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    With an elastic negative pole being driven by ultra so nic vibration and being moved along the surface of work-piece compliantly by ro bot, a new kind of effective EDM, the compliant EDM, cuts the electrically condu ctive materials away and polishes work-piece of free-form surface. The study o f the contact force between the end of polishing tool and the surface of work-p iece is the key for the compliant EDM to study its cutting mechanism and to make better use of it. This paper makes a model for the cont...

  9. 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

  10. Magnetic force improvement and parameter optimization for magnetic abrasive polishing of AZ31 magnesium alloy

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The magnetic force acting on workpieee to be machined plays a significantly important role in magnetic abrasive polishing process.But in a case of polishing nonferrous materials,the strength of magnetic force is very low and it leads lower polishing efficiency.The magnesium alloy that has superior mechanical properties for industrial application such as a lightweight and high specific strength is one of the most famous nonferrous materials.An improving strategy of the magnetic force for me AZ31 magnesium alloy installed with a permanent magnet was proposed and experimental verification Was carded out.For the proposed strategy,the effect of process parameters on the surface roughness of the AZ31 magnesium alloy Was evaluated by a design of experimental method.

  11. PROBABILISTIC STATISTICAL ASSESSMENT OF SURFACE ROUGHNESS OF PARTS BEING POLISHED WHILE USING ELECTRIC PULSE METHOD

    Directory of Open Access Journals (Sweden)

    Y. V. Sinkevich

    2011-01-01

    Full Text Available The paper presents methodology and results of investigations pertaining to profilograms of specimen surfaces being polished using electric pulse method and being made of steel 10 и 20Х13 with the help of correlative transformation. It has been established that in the process of polishing topography formation is initiated due to simultaneous surfacing of micro- and sub-micro-irregularities with equal probability and equal intensity. The obtained mechanism for topography formation is justified by the fact that break-down of gas-vapor shell takes place with equal probability as on the micro-profile top so in its cavities on the polished surface in the zones of accidental  non-homogeneity of electric field.

  12. Effect of chemical environment and rock composition on fracture mechanics properties of reservoir lithologies in context of CO2 sequestration

    Science.gov (United States)

    Major, J. R.; Eichhubl, P.; Callahan, O. A.

    2015-12-01

    The coupled chemical and mechanical response of reservoir and seal rocks to injection of CO2 have major implications on the short and long term security of sequestered carbon. Many current numerical models evaluating behavior of reservoirs and seals during and after CO2 injection in the subsurface consider chemistry and mechanics separately and use only simple mechanical stability criteria while ignoring time-dependent failure parameters. CO2 injection irreversibly alters the subsurface chemical environment which can then affect geomechanical properties on a range of time scales by altering rock mineralogy and cements through dissolution, remobilization, and precipitation. It has also been documented that geomechanical parameters such as fracture toughness (KIC) and subcritical index (SCI) are sensitive to chemical environment. Double torsion fracture mechanics testing of reservoir lithologies under controlled environmental conditions relevant to CO2 sequestration show that chemical environment can measurably affect KIC and SCI. This coupled chemical-mechanical behavior is also influenced by rock composition, grains, amount and types of cement, and fabric. Fracture mechanics testing of the Aztec Sandstone, a largely silica-cemented, subarkose sandstone demonstrate it is less sensitive to chemical environment than Entrada Sandstone, a silty, clay-rich sandstone. The presence of de-ionized water lowers KIC by approximately 20% and SCI 30% in the Aztec Sandstone relative to tests performed in air, whereas the Entrada Sandstone shows reductions on the order of 70% and 90%, respectively. These results indicate that rock composition influences the chemical-mechanical response to deformation, and that the relative chemical reactivity of target reservoirs should be recognized in context of CO2 sequestration. In general, inert grains and cements such as quartz will be less sensitive to the changing subsurface environment than carbonates and clays.

  13. Freeform correction polishing for optics with semi-kinematic mounting

    Science.gov (United States)

    Huang, Chien-Yao; Kuo, Ching-Hsiang; Peng, Wei-Jei; Yu, Zong-Ru; Ho, Cheng-Fang; Hsu, Ming-Ying; Hsu, Wei-Yao

    2015-10-01

    Several mounting configurations could be applied to opto-mechanical design for achieving high precise optical system. The retaining ring mounting is simple and cost effective. However, it would deform the optics due to its unpredictable over-constraint forces. The retaining ring can be modified to three small contact areas becoming a semi-kinematic mounting. The semi-kinematic mounting can give a fully constrained in lens assembly and avoid the unpredictable surface deformation. However, there would be still a deformation due to self-weight in large optics especially in vertical setup applications. The self-weight deformation with a semi-kinematic mounting is a stable, repeatable and predictable combination of power and trefoil aberrations. This predictable deformation can be pre-compensated onto the design surface and be corrected by using CNC polisher. Thus it is a freeform surface before mounting to the lens cell. In this study, the freeform correction polishing is demonstrated in a Φ150 lens with semi-kinematic mounting. The clear aperture of the lens is Φ143 mm. We utilize ANSYS simulation software to analyze the lens deformation due to selfweight deformation with semi-kinematic mounting. The simulation results of the self-weight deformation are compared with the measurement results of the assembled lens cell using QED aspheric stitching interferometer (ASI). Then, a freeform surface of a lens with semi-kinematic mounting due to self-weight deformation is verified. This deformation would be corrected by using QED Magnetorheological Finishing (MRF® ) Q-flex 300 polishing machine. The final surface form error of the assembled lens cell after MRF figuring is 0.042 λ in peak to valley (PV).

  14. Design Considerations of Polishing Lap for Computer-Controlled Cylindrical Polishing Process

    Science.gov (United States)

    Khan, Gufran S.; Gubarev, Mikhail; Speegle, Chet; Ramsey, Brian

    2010-01-01

    The future X-ray observatory missions, such as International X-ray Observatory, require grazing incidence replicated optics of extremely large collecting area (3 m2) in combination with angular resolution of less than 5 arcsec half-power diameter. The resolution of a mirror shell depends ultimately on the quality of the cylindrical mandrels from which they are being replicated. Mid-spatial-frequency axial figure error is a dominant contributor in the error budget of the mandrel. This paper presents our efforts to develop a deterministic cylindrical polishing process in order to keep the mid-spatial-frequency axial figure errors to a minimum. Simulation studies have been performed to optimize the operational parameters as well as the polishing lap configuration. Furthermore, depending upon the surface error profile, a model for localized polishing based on dwell time approach is developed. Using the inputs from the mathematical model, a mandrel, having conical approximated Wolter-1 geometry, has been polished on a newly developed computer-controlled cylindrical polishing machine. We report our first experimental results and discuss plans for further improvements in the polishing process.

  15. Critical Chemical-Mechanical Couplings that Define Permeability Modifications in Pressure-Sensitive Rock Fractures

    Energy Technology Data Exchange (ETDEWEB)

    Derek Elsworth; Abraham Grader; Susan Brantley

    2007-04-25

    This work examined and quantified processes controlling changes in the transport characteristics of natural fractures, subjected to coupled thermal-mechanical-chemical (TMC) effects. Specifically, it examined the effects of mineral dissolution and precipitation mediated by mechanical effects, using laboratory through-flow experiments concurrently imaged by X-ray CT. These were conducted on natural and artificial fractures in cores using water as the permeant. Fluid and mineral mass balances are recorded and are correlated with in-sample saturation, porosity and fracture aperture maps, acquired in real-time by X-ray CT-imaging at a maximum spatial resolution of 15-50 microns per pixel. Post-test, the samples were resin-impregnated, thin-sectioned, and examined by microscopy to define the characteristics of dissolution and precipitation. The test-concurrent X-ray imaging, mass balances, and measurements of permeability, together with the post-test microscopy, were used to define dissolution/precipitation processes, and to constrain process-based models. These models define and quantify key processes of pressure solution, free-face dissolution, and shear-dilation, and the influence of temperature, stress level, and chemistry on the rate of dissolution, its distribution in space and time, and its influence on the mechanical and transport properties of the fracture.

  16. Tooth polishing: Relevance in present day periodontal practice

    Directory of Open Access Journals (Sweden)

    Madan Charu

    2009-01-01

    Full Text Available Time has seen the emergence of more efficient and effective devices like jet abrasives. However, the role of rubber cups with prophy angles cannot be overlooked as they are still being widely used and provide an economical alternative. Owing to several shortcomings associated with the air polishing device using sodium bicarbonate (NaHCO 3 , trends are shifting towards the usage of low abrasive powders. Recent demonstration of Glycine Powder Air Polishing (GPAP in removing subgingival biofilm results in less gingival erosion than hand instrumentation or NaHCO 3 air-polishing. Despite the emergence of latest advances in polishing, data suggesting selective polishing of teeth is compelling.

  17. Polishing Material Removal Correlation on PMMA - FEM Simulation

    Science.gov (United States)

    Almeida, R.; Börret, R.; Rimkus, W.; Harrison, D. K.; DeSilva, A. K. M.

    2016-02-01

    The complexity of polishing is very high and experience in this field is required to achieve reproducible deterministic results concerning shape accuracy. The goal of this work is to predict the material removal of the polishing process on PMMA (Polymethylmethacrylate) using an industrial robot polisher. In order to predict the material removal, a FEM Model was created representing the polishing process. This model will help to predict the material removal when polishing parameters are changed. Experiments were carried out and compared to the results obtained from the different parameters tested in the simulation.

  18. Hybrid Cleaning Technology for Enhanced Post-Cu/Low-Dielectric Constant Chemical Mechanical Planarization Cleaning Performance

    Science.gov (United States)

    Ramachandran, Manivannan; Cho, Byoung-Jun; Kwon, Tae-Young; Park, Jin-Goo

    2013-05-01

    During chemical mechanical planarization (CMP), a copper/low-k surface is often contaminated by abrasive particles, organic materials and other additives. These contaminants need to be removed in the subsequent cleaning process with minimum material loss. In this study, a dilute amine-based alkaline cleaning solution is used along with physical force in the form of megasonic energy to remove particles and organic contaminants. Tetramethylammonium hydroxide (TMAH) and monoethanolamine (MEA) are used as an organic base and complexing agent, respectively, in the proposed solution. Ethanolamine acts as a corrosion inhibitor in the solution. Organic residue removal was confirmed through contact angle measurements and X-ray photoelectron spectroscopy analysis. Electrochemical studies showed that the proposed solution increases protection against corrosion, and that the hybrid cleaning technology resulted in higher particle removal efficiency from both the copper and low-k surfaces.

  19. An Improved Chemical Resistance and Mechanical Durability of Hydrophobic FDTS Coatings

    Science.gov (United States)

    Kobrin, B.; Zhang, T.; Grimes, M. T.; Chong, K.; Wanebo, M.; Chinn, J.; Nowak, R.

    2006-04-01

    Chemical and mechanical stability of FDTS (perfluorodecyltrichlorosilane) hydrophobic coatings was improved by using an oxide adhesion layer followed by an in-situ vapour deposition of the FDTS self-aligned monolayer. The use of silicon oxide base layer improves stability of the FDTS film and degradation of its hydrophobic properties resulting from a continuous immersion in water and other liquids. We ascribe the improved stability of the FDTS films grown on oxide to high density and uniformity of the surface hydroxyl groups required for FDTS attachment and the resulting high quality of the FDTS monolayer. This approach shows film property improvement over traditional substrates such as silicon and aluminium but may also be particularly useful in biochemistry and micro fluidics when films are deposited on substrates with lower density of the surface hydroxyl groups.

  20. Dual Raman-Brillouin Microscope for Chemical and Mechanical Characterization and Imaging.

    Science.gov (United States)

    Traverso, Andrew J; Thompson, Jonathan V; Steelman, Zachary A; Meng, Zhaokai; Scully, Marlan O; Yakovlev, Vladislav V

    2015-08-01

    We present a unique confocal microscope capable of measuring the Raman and Brillouin spectra simultaneously from a single spatial location. Raman and Brillouin scattering offer complementary information about a material's chemical and mechanical structure, respectively, and concurrent monitoring of both of these spectra would set a new standard for material characterization. We achieve this by applying recent innovations in Brillouin spectroscopy that reduce the necessary acquisition times to durations comparable to conventional Raman spectroscopy while attaining a high level of spectral accuracy. To demonstrate the potential of the system, we map the Raman and Brillouin spectra of a molded poly(ethylene glycol) diacrylate (PEGDA) hydrogel sample in cyclohexane to create two-dimensional images with high contrast at microscale resolutions. This powerful tool has the potential for very diverse analytical applications in basic science, industry, and medicine.

  1. Effects of He-Ne laser beam on mechanical, heat, chemical and superficial wounds

    International Nuclear Information System (INIS)

    This study summarizes the effects of low-doses of He-Ne laser radiation (λ = 6328 A), on healing of four types of wounds, including mechanical, heat, chemical and superficial wounds. The results revealed that variations between complete wound-closure in irradiated samples and that of control groups were statistically significant. Moreover, the results suggest that the stimulative action of laser is an accumulative phenomenon, that affects factors involved in the course of wound healing. The results also indicate that the skin epithelium is a highly responsive tissue towards this sort of radiation, which suggests that the stimulative action of He-Ne laser could be assayed easily by using such tissues as a test target. (author). 11 refs, 2 tabs

  2. Surfactant-controlled damage evolution during chemical mechanical planarization of nanoporous films

    International Nuclear Information System (INIS)

    The integration of nanoporous organosilicate thin films involving chemical mechanical planarization (CMP) is a significant challenge due the evolution of defects in the films during CMP in the form of cracking and delamination. This study shows that small changes in CMP electrolyte chemistry and surfactant additions can have dramatic effects on crack growth rates in the films. Crack growth rates were sensitive to the type of electrolyte and decreased in the presence of electrolytes that caused crack tip blunting. Growth rates were also sensitive to nonionic surfactant additions where molecular structure and weight were demonstrated to be important variables. An optimized blend of surfactants and electrolytes can significantly retard defect evolution due to molecular bridging. Surfactant self-assembly and resulting molecular bridging were characterized by in situ atomic force microscopy and used to quantify the molecular bridging observed.

  3. Band gap engineering in polymers through chemical doping and applied mechanical strain.

    Science.gov (United States)

    Lanzillo, Nicholas A; Breneman, Curt M

    2016-08-17

    We report simulations based on density functional theory and many-body perturbation theory exploring the band gaps of common crystalline polymers including polyethylene, polypropylene and polystyrene. Our reported band gaps of 8.6 eV for single-chain polyethylene and 9.1 eV for bulk crystalline polyethylene are in excellent agreement with experiment. The effects of chemical doping along the polymer backbone and side-groups are explored, and the use mechanical strain as a means to modify the band gaps of these polymers over a range of several eV while leaving the dielectric constant unchanged is discussed. This work highlights some of the opportunities available to engineer the electronic properties of polymers with wide-reaching implications for polymeric dielectric materials used for capacitive energy storage. PMID:27324304

  4. Insight into the mechanisms of chemical doping of graphene on silicon carbide.

    Science.gov (United States)

    Giannazzo, Filippo

    2016-02-19

    Graphene (Gr) is currently the object of intense research investigations, owing to its rich physics and wide potential for applications. In particular, epitaxial Gr on silicon carbide (SiC) holds great promise for the development of new device concepts based on the vertical current transport at Gr/SiC heterointerface. Precise tailoring of Gr workfunction (WF) represents a key requirement for these device structures. In this context, Günes et al (2015 Nanotechnology 26 445702) recently reported a straightforward approach for WF modulation in epitaxial Gr on silicon carbide by using nitric acid solutions at different dilutions. This paper provides a deep insight on the peculiar mechanisms of chemical doping of epitaxial Gr on 4H-SiC(0001), using several characterization techniques (Raman, UPS, AFM) and density functional theory calculations. The relevance of these findings and their perspective applications in emerging device concepts based on monolithic integration of Gr and SiC will be discussed. PMID:26782771

  5. Band gap engineering in polymers through chemical doping and applied mechanical strain

    Science.gov (United States)

    Lanzillo, Nicholas A.; Breneman, Curt M.

    2016-08-01

    We report simulations based on density functional theory and many-body perturbation theory exploring the band gaps of common crystalline polymers including polyethylene, polypropylene and polystyrene. Our reported band gaps of 8.6 eV for single-chain polyethylene and 9.1 eV for bulk crystalline polyethylene are in excellent agreement with experiment. The effects of chemical doping along the polymer backbone and side-groups are explored, and the use mechanical strain as a means to modify the band gaps of these polymers over a range of several eV while leaving the dielectric constant unchanged is discussed. This work highlights some of the opportunities available to engineer the electronic properties of polymers with wide-reaching implications for polymeric dielectric materials used for capacitive energy storage.

  6. Kandelia obovata (S., L.) Yong tolerance mechanisms to Cadmium: subcellular distribution, chemical forms and thiol pools.

    Science.gov (United States)

    Weng, Bosen; Xie, Xiangyu; Weiss, Dominik J; Liu, Jingchun; Lu, Haoliang; Yan, Chongling

    2012-11-01

    In order to explore the detoxification mechanisms adopted by mangrove under cadmium (Cd) stress, we investigated the subcellular distribution and chemical forms of Cd, in addition to the change of the thiol pools in Kandelia obovata (S., L.) Yong, which were cultivated in sandy culture medium treated with sequential Cd solution. We found that Cd addition caused a proportional increase of Cd in the organs of K. obovata. The investigation of subcellular distribution verified that most of the Cd was localized in the cell wall, and the lowest was in the membrane. Results showed sodium chloride and acetic acid extractable Cd fractions were dominant. The contents of non-protein thiol compounds, Glutathione and phytochelatins in K. obovata were enhanced by the increasing strength of Cd treatment. Therefore, K. obovata can be defined as Cd tolerant plant, which base on cell wall compartmentalization, as well as protein and organic acids combination.

  7. Panel report on coupled thermo-mechanical-hydro-chemical processes associated with a nuclear waste repository

    International Nuclear Information System (INIS)

    Four basic physical processes, thermal, hydrological, mechanical and chemical, are likely to occur in 11 different types of coupling during the service life of an underground nuclear waste repository. A great number of coupled processes with various degrees of importance for geological repositories were identified and arranged into these 11 types. A qualitative description of these processes and a tentative evaluation of their significance and the degree of uncertainty in prediction is given. Suggestions for methods of investigation generally include, besides theoretical work, laboratory and large scale field testing. Great efforts of a multidisciplinary nature are needed to elucidate details of several coupled processes under different temperature conditions in different geological formations. It was suggested that by limiting the maximum temperature to 1000C in the backfill and in the host rock during the whole service life of the repository the uncertainties in prediction of long-term repository behavior might be considerably reduced

  8. Insight into the mechanisms of chemical doping of graphene on silicon carbide.

    Science.gov (United States)

    Giannazzo, Filippo

    2016-02-19

    Graphene (Gr) is currently the object of intense research investigations, owing to its rich physics and wide potential for applications. In particular, epitaxial Gr on silicon carbide (SiC) holds great promise for the development of new device concepts based on the vertical current transport at Gr/SiC heterointerface. Precise tailoring of Gr workfunction (WF) represents a key requirement for these device structures. In this context, Günes et al (2015 Nanotechnology 26 445702) recently reported a straightforward approach for WF modulation in epitaxial Gr on silicon carbide by using nitric acid solutions at different dilutions. This paper provides a deep insight on the peculiar mechanisms of chemical doping of epitaxial Gr on 4H-SiC(0001), using several characterization techniques (Raman, UPS, AFM) and density functional theory calculations. The relevance of these findings and their perspective applications in emerging device concepts based on monolithic integration of Gr and SiC will be discussed.

  9. Mechanism of waste biomass pyrolysis: Effect of physical and chemical pre-treatments.

    Science.gov (United States)

    Das, Oisik; Sarmah, Ajit K

    2015-12-15

    To impart usability in waste based biomass through thermo-chemical reactions, several physical and chemical pre-treatments were conducted to gain an insight on their mode of action, effect on the chemistry and the change in thermal degradation profiles. Two different waste biomasses (Douglas fir, a softwood and hybrid poplar, a hardwood) were subjected to four different pre-treatments, namely, hot water pre-treatment, torrefaction, acid (sulphuric acid) and salt (ammonium phosphate) doping. Post pre-treatments, the changes in the biomass structure, chemistry, and thermal makeup were studied through electron microscopy, atomic absorption/ultra violet spectroscopy, ion exchange chromatography, and thermogravimetry. The pre-treatments significantly reduced the amounts of inorganic ash, extractives, metals, and hemicellulose from both the biomass samples. Furthermore, hot water and torrefaction pre-treatment caused mechanical disruption in biomass fibres leading to smaller particle sizes. Torrefaction of Douglas fir wood yielded more solid product than hybrid poplar. Finally, the salt pre-treatment increased the activation energies of the biomass samples (especially Douglas fir) to a great extent. Thus, salt pre-treatment was found to bestow thermal stability in the biomass. PMID:26282766

  10. Biocomposites from waste derived biochars: Mechanical, thermal, chemical, and morphological properties.

    Science.gov (United States)

    Das, Oisik; Sarmah, Ajit K; Bhattacharyya, Debes

    2016-03-01

    To identify a route for organic wastes utilisation, biochar made from various feedstocks (landfill pine saw dust, sewage sludge, and poultry litter) and at diverse pyrolysis conditions, were collected. These biochars were used to fabricate wood and polypropylene biocomposites with a loading level of 24 mass%. The composites were tested for their mechanical, chemical, thermal, morphological, and fire properties. The poultry litter biochar biocomposite, with highest ash content, was found to have high values of tensile/flexural strength, tensile/flexural modulus, and impact strength, compared to other composites. In general, addition of all the biochars enhanced the tensile/flexural moduli of the composites. The crystal structure of polypropylene in the composite was intact after the incorporation of all the biochars. The final chemical and crystal structure of the composite were an additive function of the individual components. The biochar particles along with wood acted as nucleating agents for the recrystallization of polypropylene in composite. Each component in the composites was found to decompose individually under thermal regime. The electron microscopy revealed the infiltration of polypropylene into the biochar pores and a general good dispersion in most composites. The poultry litter composite was found to have lower heat release rate under combustion regime. PMID:26724232

  11. Disruptive environmental chemicals and cellular mechanisms that confer resistance to cell death.

    Science.gov (United States)

    Narayanan, Kannan Badri; Ali, Manaf; Barclay, Barry J; Cheng, Qiang Shawn; D'Abronzo, Leandro; Dornetshuber-Fleiss, Rita; Ghosh, Paramita M; Gonzalez Guzman, Michael J; Lee, Tae-Jin; Leung, Po Sing; Li, Lin; Luanpitpong, Suidjit; Ratovitski, Edward; Rojanasakul, Yon; Romano, Maria Fiammetta; Romano, Simona; Sinha, Ranjeet K; Yedjou, Clement; Al-Mulla, Fahd; Al-Temaimi, Rabeah; Amedei, Amedeo; Brown, Dustin G; Ryan, Elizabeth P; Colacci, Annamaria; Hamid, Roslida A; Mondello, Chiara; Raju, Jayadev; Salem, Hosni K; Woodrick, Jordan; Scovassi, A Ivana; Singh, Neetu; Vaccari, Monica; Roy, Rabindra; Forte, Stefano; Memeo, Lorenzo; Kim, Seo Yun; Bisson, William H; Lowe, Leroy; Park, Hyun Ho

    2015-06-01

    Cell death is a process of dying within biological cells that are ceasing to function. This process is essential in regulating organism development, tissue homeostasis, and to eliminate cells in the body that are irreparably damaged. In general, dysfunction in normal cellular death is tightly linked to cancer progression. Specifically, the up-regulation of pro-survival factors, including oncogenic factors and antiapoptotic signaling pathways, and the down-regulation of pro-apoptotic factors, including tumor suppressive factors, confers resistance to cell death in tumor cells, which supports the emergence of a fully immortalized cellular phenotype. This review considers the potential relevance of ubiquitous environmental chemical exposures that have been shown to disrupt key pathways and mechanisms associated with this sort of dysfunction. Specifically, bisphenol A, chlorothalonil, dibutyl phthalate, dichlorvos, lindane, linuron, methoxychlor and oxyfluorfen are discussed as prototypical chemical disruptors; as their effects relate to resistance to cell death, as constituents within environmental mixtures and as potential contributors to environmental carcinogenesis. PMID:26106145

  12. Mechanism of waste biomass pyrolysis: Effect of physical and chemical pre-treatments.

    Science.gov (United States)

    Das, Oisik; Sarmah, Ajit K

    2015-12-15

    To impart usability in waste based biomass through thermo-chemical reactions, several physical and chemical pre-treatments were conducted to gain an insight on their mode of action, effect on the chemistry and the change in thermal degradation profiles. Two different waste biomasses (Douglas fir, a softwood and hybrid poplar, a hardwood) were subjected to four different pre-treatments, namely, hot water pre-treatment, torrefaction, acid (sulphuric acid) and salt (ammonium phosphate) doping. Post pre-treatments, the changes in the biomass structure, chemistry, and thermal makeup were studied through electron microscopy, atomic absorption/ultra violet spectroscopy, ion exchange chromatography, and thermogravimetry. The pre-treatments significantly reduced the amounts of inorganic ash, extractives, metals, and hemicellulose from both the biomass samples. Furthermore, hot water and torrefaction pre-treatment caused mechanical disruption in biomass fibres leading to smaller particle sizes. Torrefaction of Douglas fir wood yielded more solid product than hybrid poplar. Finally, the salt pre-treatment increased the activation energies of the biomass samples (especially Douglas fir) to a great extent. Thus, salt pre-treatment was found to bestow thermal stability in the biomass.

  13. Photofunctionalization of Titanium: An Alternative Explanation of Its Chemical-Physical Mechanism

    Science.gov (United States)

    Pompella, Alfonso; Kubacki, Jerzy; Szade, Jacek; Roy, Robert A.; Hedzelek, Wieslaw

    2016-01-01

    Objectives To demonstrate that titanium implant surfaces as little as 4 weeks from production are contaminated by atmospheric hydrocarbons. This phenomenon, also known as biological ageing can be reversed by UVC irradiation technically known as photofunctionalization. To propose a new model from our experimental evidence to explain how the changes in chemical structure of the surface will affect the adsorption of amino acids on the titanium surface enhancing osteointegration. Methods In our study XPS and AES were used to analyze the effects of UVC irradiation (photofunctionalization) in reversing biological ageing of titanium. SEM was used to analyze any possible effects on the topography of the surface. Results UVC irradiation was able to reverse biological ageing of titanium by greatly reducing the amount of carbon contamination present on the implant surface by up to 4 times, while the topography of the surface was not affected. UVC photon energy reduces surface H2O and increases TiOH with many –OH groups being produced. These groups explain the super-hydrophilic effect from photofunctionalization when these groups come into contact with water. Significance Photofunctionalization has proven to be a valid method to reduce the amount of hydrocarbon contamination on titanium dental implants and improve biological results. The chemisorption mechanisms of amino acids, in our study, are dictated by the chemical structure and electric state present on the surface, but only in the presence of an also favourable geometrical composition at the atomical level. PMID:27309723

  14. Preparation of High Impermeable and Crack-resistance Chemical Admixture and Its Mechanism

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    A kind of high impermeable and crack-resistance chemical admixture (HICRCA) was prepared, which is a compound chemical admixture composed of an expansion ingredient,density ingredient, and organic hydrophobic poreblocking ingredient. The results of the experiments indicate that the addition of HICRCA improves mortar and concrete in the following performances:(1) perfect workability: slump is more than 22cm, the slump after 3h is about 16cm; (2)high impermeability:for the mortar,the pervious height under a water pressure of 1.5MPa is 1.5cm,for the concrete, the pervious height under a water pressure of 5.0MPa is 2.2cm;(3)high crack-resistance:there is a micro-expansion at the age of 90d;(4)high compressivestrength:compared with the controlled concrete,the compressive strengths at the age of 3d and 28d are improved by 66.4% and 62.0%, respectively.At the same time,the effects of different curing condition on mortar and concrete expansive and shrinkage performance were studied.In addition,the impermeable and crack-resistance mechanism was investigated in the present paper.

  15. Effects of thermal treatment on chemical, mechanical and colour traits in Norway spruce wood.

    Science.gov (United States)

    Kačíková, Danica; Kačík, František; Cabalová, Iveta; Durkovič, Jaroslav

    2013-09-01

    In several different branches of the wood industry heat treatment is a growing application as it changes the chemical, mechanical, physical and biological properties of wood. Investigations using wet chemical analyses, Fourier transform infrared spectroscopy, size exclusion chromatography, and CIELab colour system have been conducted to study the changes in Norway spruce wood subjected to temperature up to 270°C over a 30 min time period. The results showed that mass loss (ML), total crystallinity index (TCI) of cellulose, total colour difference (ΔE*), and the content of lignin and extractives increased with the temperature, whereas degree of polymerization (DP) of cellulose, modulus of rupture (MOR), modulus of elasticity (MOE), lightness difference (ΔL*), and the content of holocellulose, cellulose and hemicelluloses all decreased with the thermal treatment. Relationships between temperature and the examined wood traits were all fitted by exponential curves. Power law relationships were found to fit the trends for DP of cellulose with ΔE*, ΔL*, and TCI of cellulose. Also found were power law regressions for the content of hemicelluloses with MOE, MOR, ΔL*, and ML. Temperatures ranging from 20 to 187°C formed a compact cluster, clearly separated from the higher examined temperatures in the multivariate wood trait space.

  16. Mechanisms mediating environmental chemical-induced endocrine disruption in the adrenal gland

    Directory of Open Access Journals (Sweden)

    Daniel B Martinez-Arguelles

    2015-03-01

    Full Text Available Humans are continuously exposed to hundreds of man-made chemicals that pollute the environment in addition to multiple therapeutic drug treatments administered throughout life. Some of these chemicals, known as endocrine disruptors (EDs, mimic endogenous signals, thereby altering gene expression, influencing development, and promoting disease. Although EDs are eventually removed from the market or replaced with safer alternatives, new evidence suggests that early life exposure leaves a fingerprint on the epigenome, which may increase the risk of disease later in life. Epigenetic changes occurring in early life in response to environmental toxicants have been shown to affect behavior, increase cancer risk, and modify the physiology of the cardiovascular system. Thus, exposure to an ED or combination of EDs may represent a first hit to the epigenome. Only limited information is available regarding the effect of ED exposure on adrenal function. The adrenal gland controls the stress response, blood pressure, and electrolyte homeostasis. This endocrine organ therefore has an important role in physiology and is a sensitive target of EDs. We review herein the effect of ED exposure on the adrenal gland with particular focus on in utero exposure to the plasticizer di(2-ethylehyl phthalate. We discuss the challenges associated with identifying the mechanism mediating the epigenetic origins of disease and availability of biomarkers that may identify individual or population risks.

  17. Evaluation of the Chemical and Mechanical Properties of Hardening High-Calcium Fly Ash Blended Concrete

    Directory of Open Access Journals (Sweden)

    Wei-Jie Fan

    2015-09-01

    Full Text Available High-calcium fly ash (FH is the combustion residue from electric power plants burning lignite or sub-bituminous coal. As a mineral admixture, FH can be used to produce high-strength concrete and high-performance concrete. The development of chemical and mechanical properties is a crucial factor for appropriately using FH in the concrete industry. To achieve sustainable development in the concrete industry, this paper presents a theoretical model to systematically evaluate the property developments of FH blended concrete. The proposed model analyzes the cement hydration, the reaction of free CaO in FH, and the reaction of phases in FH other than free CaO. The mutual interactions among cement hydration, the reaction of free CaO in FH, and the reaction of other phases in FH are also considered through the calcium hydroxide contents and the capillary water contents. Using the hydration degree of cement, the reaction degree of free CaO in FH, and the reaction degree of other phases in FH, the proposed model evaluates the calcium hydroxide contents, the reaction degree of FH, chemically bound water, porosity, and the compressive strength of hardening concrete with different water to binder ratios and FH replacement ratios. The evaluated results are compared to experimental results, and good consistencies are found.

  18. The chemical and mechanical behaviors of polymer / reactive metal systems under high strain rates

    Science.gov (United States)

    Shen, Yubin

    As one category of energetic materials, impact-initiated reactive materials are able to release a high amount of stored chemical energy under high strain rate impact loading, and are used extensively in civil and military applications. In general, polymers are introduced as binder materials to trap the reactive metal powders inside, and also act as an oxidizing agent for the metal ingredient. Since critical attention has been paid on the metal / metal reaction, only a few types of polymer / reactive metal interactions have been studied in the literature. With the higher requirement of materials resistant to different thermal and mechanical environments, the understanding and characterization of polymer / reactive metal interactions are in great demand. In this study, PTFE (Polytetrafluoroethylene) 7A / Ti (Titanium) composites were studied under high strain rates by utilizing the Taylor impact and SHPB tests. Taylor impact tests with different impact velocities, sample dimensions and sample configurations were conducted on the composite, equipped with a high-speed camera for tracking transient images during the sudden process. SHPB and Instron tests were carried out to obtain the stress vs. strain curves of the composite under a wide range of strain rates, the result of which were also utilized for fitting the constitutive relations of the composite based on the modified Johnson-Cook strength model. Thermal analyses by DTA tests under different flow rates accompanied with XRD identification were conducted to study the reaction mechanism between PTFE 7A and Ti when only heat was provided. Numerical simulations on Taylor impact tests and microstructural deformations were also performed to validate the constitutive model built for the composite system, and to investigate the possible reaction mechanism between two components. The results obtained from the high strain rate tests, thermal analyses and numerical simulations were combined to provide a systematic study on

  19. Optimization of TiO2 and PMAPTAC Concentrations of a Chemical Humidity Sensing Mechanism

    Directory of Open Access Journals (Sweden)

    Samir Barra

    2009-09-01

    Full Text Available This work aims to achieve an optimization of the TiO2 and PMAPTAC concentrations in a chemical resistive-type humidity sensing mechanism (RHSM. Our idea is based primarily on the modeling of the sensing mechanism. This model takes into account the parameters of non-linearity, hysteresis, temperature, frequency, substrate type. Furthermore, we investigated the TiO2 and PMAPTAC effects concentrations on the humidity sensing properties in our model. Secondly, we used the Matlab environment to create a database for an ideal model for the sensing mechanism, where the response of this ideal model is linear for any value of the above parameters. We have done the training to create an analytical model for the sensing mechanism (SM and the ideal model (IM. After that, the SM and IM models are established on PSPICE simulator, where the output of the first is identical to the output of the RHSM used and the output of the last is the ideal response. Finally a “DIF bloc” was realized to make the difference between the SM output and the IM output, where this difference represents the linearity error, we take the minimum error, to identify the optimal TiO2 and PMAPTAC concentrations. However, a compromise between concentrations, humidity and temperature must be performed. The simulation results show that in low humidity and at temperature more than 25 °C, sample 1 is the best (in alumina substrate. However, the sample 9 represents the best sensor (in PET substrate predominately for the lowest humidity and temperature.

  20. Global mechanistic model of SOA formation: effects of different chemical mechanisms

    Directory of Open Access Journals (Sweden)

    G. Lin

    2011-09-01

    Full Text Available Recent experimental findings indicate that Secondary Organic Aerosol (SOA represents an important and, under many circumstances, the major fraction of the organic aerosol burden. Here, we use a global 3-d model (IMPACT to test the results of different mechanisms for the production of SOA. The basic mechanism includes SOA formation from organic nitrates and peroxides produced from an explicit chemical formulation, using partition coefficients based on thermodynamic principles. We also include the formation of non-evaporative SOA from the reaction of glyoxal and methylglyoxal on aqueous aerosols and cloud droplets as well as from the reaction of epoxides on aqueous aerosols. A model simulation including these SOA formation mechanisms gives an annual global SOA production of 113.5 Tg. The global production of SOA is substantially decreased to 85.0 Tg yr−1 if the HOx regeneration mechanism proposed by Peeters et al. (2009 is used. Model predictions with and without this HOx regeneration scheme are compared with multiple surface observation datasets, namely: the Interagency Monitoring of Protected Visual Environments (IMPROVE for the United States, the European Monitoring and Evaluation Programme (EMEP as well as Aerosol Mass Spectrometry (AMS data measured in both Northern Hemisphere and tropical forest regions. All model simulations realistically predict the organic carbon mass observed in the Northern Hemisphere, although they tend to overestimate the concentrations in tropical forest regions. This overestimate may result from an unrealistically high uptake rate of glyoxal and methylglyoxal on aqueous aerosols and in cloud drops. The modeled OC in the free troposphere is in agreement with measurements in the ITCT-2K4 aircraft campaign over the North America and in pollution layers in Asia during the INTEX-B campaign, although the model underestimates OC in the free troposphere during the ACE-Asia campaign off the

  1. Effect of pretreatment bias on the nucleation and growth mechanisms of ultrananocrystalline diamond films via bias-enhanced nucleation and growth: An approach to interfacial chemistry analysis via chemical bonding mapping

    International Nuclear Information System (INIS)

    The effect of pretreatment bias on the nucleation and growth mechanisms of the ultrananocrystalline diamond (UNCD) films on the Si substrate via bias-enhanced nucleation and bias-enhanced growth (BEN-BEG) was investigated using cross-sectional high-resolution transmission electron microscopy, chemical bonding mapping, and Raman spectroscopy. The mirror-polished substrate surface showed the formation of a triangular profile produced by a dominant physical sputtering mechanism induced by ion bombardment of ions from the hydrogen plasma accelerated toward the substrate due to biasing and a potential hydrogen-induced chemical reaction component before synthesizing the UNCD films. The BEN-BEG UNCD films grown on the Si substrate with biased and unbiased pretreatments in the hydrogen plasma were compared. In the case of the bias-pretreated substrate, the SiC phases were formed at the peaks of the Si surface triangular profile due to the active unsaturated Si bond and the enhanced local electrical field. The UNCD grains grew preferentially at the peaks of the triangular substrate surface profile and rapidly covered the amorphous carbon (a-C) and oriented graphite phases formed in the valley of the surface profile. In the case of the substrate with unbiased pretreatment, the SiC phases were formed via the reactions between the hydrocarbon species and the active Si atoms released from the substrate with assistance of the hydrogen plasma. The UNCD grains nucleated on the nucleating sites consisting of the SiC, a-C, and graphite phases. Growth mechanisms for the BEN-BEG UNCD films on both Si substrates were proposed to elucidate the different nucleation processes. Applying bias on the Si substrate pretreated in the hydrogen plasma optimized the nucleation sites for growth of UNCD grains, resulting in the low content of the nondiamond phases in UNCD films

  2. Photochemical modeling in California with two chemical mechanisms: model intercomparison and response to emission reductions.

    Science.gov (United States)

    Cai, Chenxia; Kelly, James T; Avise, Jeremy C; Kaduwela, Ajith P; Stockwell, William R

    2011-05-01

    An updated version of the Statewide Air Pollution Research Center (SAPRC) chemical mechanism (SAPRC07C) was implemented into the Community Multiscale Air Quality (CMAQ) version 4.6. CMAQ simulations using SAPRC07C and the previously released version, SAPRC99, were performed and compared for an episode during July-August, 2000. Ozone (O3) predictions of the SAPRC07C simulation are generally lower than those of the SAPRC99 simulation in the key areas of central and southern California, especially in areas where modeled concentrations are greater than the federal 8-hr O3 standard of 75 parts per billion (ppb) and/or when the volatile organic compound (VOC)/nitrogen oxides (NOx) ratio is less than 13. The relative changes of ozone production efficiency (OPE) against the VOC/NOx ratio at 46 sites indicate that the OPE is reduced in SAPRC07C compared with SAPRC99 at most sites by as much as approximately 22%. The SAPRC99 and SAPRC07C mechanisms respond similarly to 20% reductions in anthropogenic VOC emissions. The response of the mechanisms to 20% NOx emissions reductions can be grouped into three cases. In case 1, in which both mechanisms show a decrease in daily maximum 8-hr O3 concentration with decreasing NOx emissions, the O3 decrease in SAPRC07C is smaller. In case 2, in which both mechanisms show an increase in O3 with decreasing NOx emissions, the O3 increase is larger in SAPRC07C. In case 3, SAPRC07C simulates an increase in O3 in response to reduced NOx emissions whereas SAPRC99 simulates a decrease in O3 for the same region. As a result, the areas where NOx controls would be disbeneficial are spatially expanded in SAPRC07C. Although the results presented here are valuable for understanding differences in predictions and model response for SAPRC99 and SAPRC07C, the study did not evaluate the impact of mechanism differences in the context of the U.S. Environmental Protection Agency's guidance for using numerical models in demonstrating air quality attainment

  3. Photochemical modeling in California with two chemical mechanisms: model intercomparison and response to emission reductions.

    Science.gov (United States)

    Cai, Chenxia; Kelly, James T; Avise, Jeremy C; Kaduwela, Ajith P; Stockwell, William R

    2011-05-01

    An updated version of the Statewide Air Pollution Research Center (SAPRC) chemical mechanism (SAPRC07C) was implemented into the Community Multiscale Air Quality (CMAQ) version 4.6. CMAQ simulations using SAPRC07C and the previously released version, SAPRC99, were performed and compared for an episode during July-August, 2000. Ozone (O3) predictions of the SAPRC07C simulation are generally lower than those of the SAPRC99 simulation in the key areas of central and southern California, especially in areas where modeled concentrations are greater than the federal 8-hr O3 standard of 75 parts per billion (ppb) and/or when the volatile organic compound (VOC)/nitrogen oxides (NOx) ratio is less than 13. The relative changes of ozone production efficiency (OPE) against the VOC/NOx ratio at 46 sites indicate that the OPE is reduced in SAPRC07C compared with SAPRC99 at most sites by as much as approximately 22%. The SAPRC99 and SAPRC07C mechanisms respond similarly to 20% reductions in anthropogenic VOC emissions. The response of the mechanisms to 20% NOx emissions reductions can be grouped into three cases. In case 1, in which both mechanisms show a decrease in daily maximum 8-hr O3 concentration with decreasing NOx emissions, the O3 decrease in SAPRC07C is smaller. In case 2, in which both mechanisms show an increase in O3 with decreasing NOx emissions, the O3 increase is larger in SAPRC07C. In case 3, SAPRC07C simulates an increase in O3 in response to reduced NOx emissions whereas SAPRC99 simulates a decrease in O3 for the same region. As a result, the areas where NOx controls would be disbeneficial are spatially expanded in SAPRC07C. Although the results presented here are valuable for understanding differences in predictions and model response for SAPRC99 and SAPRC07C, the study did not evaluate the impact of mechanism differences in the context of the U.S. Environmental Protection Agency's guidance for using numerical models in demonstrating air quality attainment

  4. Computer modelling system of the chemical composition and treatment parameters influence on mechanical properties of structural steels

    OpenAIRE

    L.A. Dobrzański; R. Honysz

    2009-01-01

    Purpose: This paper presents Neuro-Lab. It is an authorship programme, which use algorithms of artificial intelligence for structural steels mechanical properties estimation.Design/methodology/approach: On the basis of chemical composition, parameters of heat and mechanical treatment and elements of geometrical shape and size this programme has the ability to calculate the mechanical properties of examined steel and introduce them as raw numeric data or in graphic as influence charts. Possibl...

  5. Polish Government policy for coal (1989-2006)

    Energy Technology Data Exchange (ETDEWEB)

    Piotr Zientara

    2007-07-01

    The purpose of this paper is to discuss and assess the consecutive Governments' policy for coal (1989-2006) in the context of the systemic transformation of the Polish economy. The paper presents a critical analysis of the rationale and effectiveness of government efforts to restructure the Polish coal mining industry in the light of economic theory, published literature, and a survey of three collieries. Some parallels, toutes proportions gardees, are drawn between the situation in the UK under Margaret Thatcher and that in Poland. The paper argues that, despite throwing billions of zlotys at the industry in the form of direct subsidies and debt write-offs, decision makers failed to make the collieries economically sound. The weaknesses of the consecutive governments - manifesting itself, amongst other things, in the unwillingness and/or inability to confront the miners' unions, to introduce market mechanisms into the sector, to ensure competent management and, crucially, to press on with nationwide economic liberalisation - are seen as the principal reasons behind the failure.

  6. Physico-chemical mechanisms governing the adherence of starch granules on materials with different hydrophobicities.

    Science.gov (United States)

    Detry, Jean G; Sindic, Marianne; Servais, Marjorie J; Adriaensen, Yasmine; Derclaye, Sylvie; Deroanne, Claude; Rouxhet, Paul G

    2011-03-01

    The factors influencing the adherence of starch were examined to improve the understanding of the mechanisms affecting soiling and cleanability. Therefore an aqueous suspension of starch granules was sprayed on four model substrates (glass, stainless steel, polystyrene and PTFE) and dried, and the substrates were cleaned using a radial-flow cell. The morphology of the soiled surfaces and the substrate chemical composition were also characterized. By influencing droplet spreading and competition between granule-substrate and granule-granule interfaces regarding the action of capillary forces, substrate wettability affected the shape and compactness of the adhering aggregates, the efficiency of shear forces upon cleaning, and finally the adherence of soiling particles. The rate of drying had an influence explained by the duration left to capillary forces for acting. X-ray photoelectron spectroscopy demonstrated the presence of macromolecules, mainly polysaccharides, which were adsorbed from the liquid phase, or carried by the retracting water film and deposited at the granule-substrate interface. These macromolecules acted as an adhesive joint, the properties of which seemed to be influenced by the detailed history of drying and subsequent exposure to humidity. In summary, the substrate surface energy affects the adherence of starch aggregates by different mechanisms which are all linked together: suspension droplet spreading, action of capillary forces, direct interaction with starch particles and interfacial macromolecules.

  7. Mechanisms of chemical modification of neoplastic cell transformation by ionizing radiation

    International Nuclear Information System (INIS)

    During space travel, astronauts will be continuously exposed to ionizing radiation; therefore, it is necessary to minimize the radiation damage by all possible means. The authors' studies show that DMSO (when present during irradiation) can protect cells from being killed and transformed by X rays and that low concentration of DMSO can reduce the transformation frequency significantly when it is applied to cells, even many days after irradiation. The process of neoplastic cell transformation is a complicated one and includes at least two different stages: induction and expression. DMSO apparently can modify the radiation damage during both stages. There are several possible mechanisms for the DMSO effect: (1) changing the cell membrane structure and properties; (2) inducing cell differentiation by acting on DNA; and (3) scavanging free radicals in the cell. Recent studies with various chemical agents, e.g., 5-azacytidine, dexamethane, rhodamin-123, etc., indicate that the induction of cell differentiation by acting on DNA may be an important mechanism for the suppression of expression of neoplastic cell transformation by DMSO

  8. Influence of oxidant passivation on controlling dishing in alkaline chemical mechanical planarization

    International Nuclear Information System (INIS)

    The article studied the electrochemical behavior of P2 alkaline polishing slurry. The main research is the changing discipline of Ecorr and Icorr in the Cu electrolyte at different concentrations of oxidant H2O2. It compares potentiodynamic polarization curves in different P2 slurries and analyzes the passivation function of H2O2 acting on controlling dishing. The result implies that the potential increases gradually and then levels off while the current density on the contrary decreases with the augment of H2O2 concentration. In addition, dishing declines with the increasing of H2O2 along with the optimization of planarization of the alkaline P2 slurry. (paper)

  9. Agglomeration patterns in the Polish manufacturing industry

    Directory of Open Access Journals (Sweden)

    Tomasz Brodzicki

    2012-01-01

    Full Text Available External liberalization should affect regional agglomeration patterns in manufacturing industry. In Poland, the largest CEE economy, economic transition was marked by accelerated restructuring associated with relatively rapid external trade and capital flows liberalization. The process of economic transition was reinforced by accession to the EU. Economic transition could potentially have a sizeable impact on industrial agglomeration patterns. Using sectoral agglomeration indices we examine changes in the agglomeration patterns of the Polish manufacturing industry. The analysis is carried out on a disaggregated data set on employment for 2 and 3-digit NACE manufacturing industry sectors at the level of local administrative districts (LAD4 level. The data set covers the period 1999-2006. The overall agglomeration index for Polish manufacturing industry decreased only by 0.5 percent within the analyzed period of time. The patter of agglomeration remained largely unaffected despite of significant structural adjustments in other areas.

  10. Activation of chemical biological defense mechanisms and remission of vital oxidative injury by low dose radiation

    Energy Technology Data Exchange (ETDEWEB)

    Yamaoka, K. [Okayama University Medical School, Okayama (Japan); Nomura, T. [Central Research Institute of Electric Power Industry, Tokyo (Japan); Kojima, S. [Science University of Tokyo, Chiba (Japan)

    2000-05-01

    Excessive active oxygen produced in vivo by various causes is toxic. Accumulation of oxidation injuries due to excessive active causes cell and tissue injuries, inducing various pathologic conditions such as aging and carcinogenesis. On the other hand, there are chemical defense mechanisms in the body that eliminate active oxygen or repair damaged molecules, defending against resultant injury. It is interesting reports that appropriate oxidation stress activate the chemical biological defense mechanisms. In this study, to elucidate these phenomena and its mechanism by low dose radiation, we studied on the below subjects. Activation of chemical biological defense mechanisms by low dose radiation: (1) The effects radiation on lipid peroxide (LPO) levels in the organs, membrane fluidity and the superoxide dismutase (SOD) activity were examined in rats and rabbits. Rats were irradiated with low dose X-ray over their entire bodies, and rabbits inhaled vaporized radon spring water, which primarily emitted {alpha}-ray. The following results were obtained. Unlike high dose X-ray, low dose X-ray and radon inhalation both reduced LPO levels and made the state of the SH-group on membrane-bound proteins closer to that of juvenile animals, although the sensitivity to radioactivity varied depending on the age of the animals and among different organs and tissues. The SOD activity was elevated, suggesting that low dose X-ray and radon both activate the host defensive function. Those changes were particularly marked in the organs related to immune functions of the animals which received low dose X-ray, while they were particularly marked in the brain after radon inhalation. It was also found that those changes continued for longer periods after low dose X-irradiation. (2) Since SOD is an enzyme that mediates the dismutation of O{sub 2}- to H{sub 2}O{sub 2}, the question as to whether the resultant H{sub 2}O{sub 2} is further detoxicated into H{sub 2}O and O{sub 2} or not must

  11. Multiple stressor effects in Chlamydomonas reinhardtii – Toward understanding mechanisms of interaction between effects of ultraviolet radiation and chemical pollutants

    International Nuclear Information System (INIS)

    Highlights: • Systematic study of multiple stressor effects of UVR and chemicals in C. reinhardtii. • UVR and chemicals did not act independently on algal photosynthesis and reproduction. • Multiple stressor effects of UVR and chemicals depended on chemical MOA. • Synergistic effect interactions not limited to oxidative stress inducing chemicals. • Multiple MOAs of UVR may limit applicability of current prediction models. - Abstract: The effects of chemical pollutants and environmental stressors, such as ultraviolet radiation (UVR), can interact when organisms are simultaneously exposed, resulting in higher (synergistic) or lower (antagonistic) multiple stressor effects than expected based on the effects of single stressors. Current understanding of interactive effects is limited due to a lack of mechanism-based multiple stressor studies. It has been hypothesized that effect interactions may generally occur if chemical and non-chemical stressors cause similar physiological effects in the organism. To test this hypothesis, we exposed the model green alga Chlamydomonas reinhardtii to combinations of UVR and single chemicals displaying modes of action (MOA) similar or dissimilar to the impact of UVR on photosynthesis. Stressor interactions were analyzed based on the independent action model. Effect interactions were found to depend on the MOA of the chemicals, and also on their concentrations, the exposure time and the measured endpoint. Indeed, only chemicals assumed to cause effects on photosynthesis similar to UVR showed interactions with UVR on photosynthetic yield: synergistic in case of Cd(II) and paraquat and antagonistic in case of diuron. No interaction on photosynthesis was observed for S-metolachlor, which acts dissimilarly to UVR. However, combined effects of S-metolachlor and UVR on algal reproduction were synergistic, highlighting the importance of considering additional MOA of UVR. Possible mechanisms of stressor effect interactions are

  12. Multiple stressor effects in Chlamydomonas reinhardtii – Toward understanding mechanisms of interaction between effects of ultraviolet radiation and chemical pollutants

    Energy Technology Data Exchange (ETDEWEB)

    Korkaric, Muris [Eawag, Swiss Federal Institute of Aquatic Science and Technology, Department of Environmental Toxicology, 8600, Duebendorf (Switzerland); ETH Zürich, Institute of Biogeochemistry and Pollutant Dynamics, 8092 Zürich (Switzerland); Behra, Renata; Fischer, Beat B. [Eawag, Swiss Federal Institute of Aquatic Science and Technology, Department of Environmental Toxicology, 8600, Duebendorf (Switzerland); Junghans, Marion [Swiss Center for Applied Ecotoxicology Eawag-EPFL, 8600, Duebendorf (Switzerland); Eggen, Rik I.L., E-mail: rik.eggen@eawag.ch [Eawag, Swiss Federal Institute of Aquatic Science and Technology, Department of Environmental Toxicology, 8600, Duebendorf (Switzerland); ETH Zürich, Institute of Biogeochemistry and Pollutant Dynamics, 8092 Zürich (Switzerland)

    2015-05-15

    Highlights: • Systematic study of multiple stressor effects of UVR and chemicals in C. reinhardtii. • UVR and chemicals did not act independently on algal photosynthesis and reproduction. • Multiple stressor effects of UVR and chemicals depended on chemical MOA. • Synergistic effect interactions not limited to oxidative stress inducing chemicals. • Multiple MOAs of UVR may limit applicability of current prediction models. - Abstract: The effects of chemical pollutants and environmental stressors, such as ultraviolet radiation (UVR), can interact when organisms are simultaneously exposed, resulting in higher (synergistic) or lower (antagonistic) multiple stressor effects than expected based on the effects of single stressors. Current understanding of interactive effects is limited due to a lack of mechanism-based multiple stressor studies. It has been hypothesized that effect interactions may generally occur if chemical and non-chemical stressors cause similar physiological effects in the organism. To test this hypothesis, we exposed the model green alga Chlamydomonas reinhardtii to combinations of UVR and single chemicals displaying modes of action (MOA) similar or dissimilar to the impact of UVR on photosynthesis. Stressor interactions were analyzed based on the independent action model. Effect interactions were found to depend on the MOA of the chemicals, and also on their concentrations, the exposure time and the measured endpoint. Indeed, only chemicals assumed to cause effects on photosynthesis similar to UVR showed interactions with UVR on photosynthetic yield: synergistic in case of Cd(II) and paraquat and antagonistic in case of diuron. No interaction on photosynthesis was observed for S-metolachlor, which acts dissimilarly to UVR. However, combined effects of S-metolachlor and UVR on algal reproduction were synergistic, highlighting the importance of considering additional MOA of UVR. Possible mechanisms of stressor effect interactions are

  13. 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.

  14. Social Responsibility Management in Polish Companies

    OpenAIRE

    Paliwoda-Matiolañska, Adriana

    2010-01-01

    Trends and changes occurring in the environment show that the social responsibility will play an increasingly important role in shaping the economic reality. The influence of non-material factors on the company’s value increases, as well as the social awareness. This article presents the evolution of the term of social responsibility, the model of social responsibility system and the practice of Polish companies with respect to CSR from the perspective of a survey among representatives of top...

  15. 241Pu in the biggest Polish rivers

    OpenAIRE

    Dagmara I. Strumińska-Parulska; Skwarzec, Bogdan

    2013-01-01

    In the paper the results of 241Pu activity concentration determination in the biggest Polish rivers are presented. The analysis of more than 100 river water samples showed the Vistula and the Odra as well as three Pomeranian Rivers are important sources of 241Pu in the southern Baltic Sea. There were differences in 241Pu activities depending on season and sampling site and the plutonium contamination came mainly from the global atmospheric fallout as well as the Chernobyl accident, which is c...

  16. Knowledge economy policy in Polish regions

    OpenAIRE

    Sokołowska-Woźniak, Justyna

    2013-01-01

    The aim of this paper is twofold. The first is to examine the level of the development of knowledge economy in Polish regions (NUTS 2 units, voivodeships). In order to assess the advances in building the knowledge economy in regions, the composite indicator for years 2003-2008 is constructed with the use of the Hellwig method based on creation of an abstract model. The second purpose is to analyse the regional authorities’ policies directed towards supporting the pillars underlying the knowle...

  17. Surftherm: A program to analyze thermochemical and kinetic data in gas-phase and surface chemical reaction mechanisms

    Energy Technology Data Exchange (ETDEWEB)

    Coltrin, M.E.; Moffat, H.K.

    1994-06-01

    This report documents the Surftherm program that analyzes transport coefficient, thermochemical- and kinetic rate information in complex gas-phase and surface chemical reaction mechanisms. The program is designed for use with the Chemkin (gas-phase chemistry) and Surface Chemkin (heterogeneous chemistry) programs. It was developed as a ``chemist`s companion`` in using the Chemkin packages with complex chemical reaction mechanisms. It presents in tabular form detailed information about the temperature and pressure dependence of chemical reaction rate constants and their reverse rate constants, reaction equilibrium constants, reaction thermochemistry, chemical species thermochemistry and transport properties. This report serves as a user`s manual for use of the program, explaining the required input and the output.

  18. Can polish university female students swim?

    Directory of Open Access Journals (Sweden)

    Podstawski Robert

    2013-06-01

    Full Text Available Background and aim of the work: There are only few studies in Polish and foreign literature providing solid information on swimming skills of university students. The aim of the study carried out at the University of Warmia & Mazury in Olsztyn was to determine swimming skills of Polish university female students starting their studies. Material and methods: The study was conducted in 2012 on 298 female students of the 1 st year course, at the age of 19 – 20. Anonymous questionnaire was used in the research. Results: It has been shown that almost 72% of the women could not swim at all, and 26% swam poorly. Within the group of women able to swim, the greatest percentage was set by women using classical style (49% and “their own” one (27% and only 13% of the students used crawl, 9% - back stroke and 2% - butterfly style. Of all the women declaring swimming abilities, the biggest percentage (16% could cover the distance of only 20 – 50 m; fewer students (6% covered the distance of 50 – 100 m; and 5% could swim only 20 m. Only a marginal number of students (2% could cover the distance from 100 to 1000 m; none could swim more than 1000 m. Conclusions: The study showed a very pessimistic picture of swimming skills of Polish university female students in respect of the number of women able to swim, their knowledge of swimming styles, and the length of the covered distance.

  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. 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 industrial optics. We report on how these ambitious requirements have stimulated an investigation into the synergy between 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.

  1. Duplication of holograms by using fingernail polish

    Science.gov (United States)

    Toxqui-López, S.; Olivares-Pérez, A.; Fuentes-Tapia, I.; Quintero-Romo, A.

    2007-08-01

    In this manuscript, we report the results of a research effort in finding an innovative recorder material which utilized fingernail polish (Super Oro One Coat®) information by means of the control of temperature as a parameter induced by hand rubbing. Analogical and computer holograms were replicated, resulting in a high quality behavior of fingernail polish through coating the polish with an average thickness of 10-15 μm, which contains some components of polyester resin with nitrocellulose. Through this material we obtained a high absolute diffraction efficiency, which was approximately equal to 90%, with gratings of 100 lines/mm. For a copy of conventional holograms at high frequencies (holographic ranges) the diffraction efficiency parameter is in the neighborhood of 22% at first order or more, depending on diffraction efficiency of the pattern of the hologram. The hologram is elaborated in the absence of any development of any process and does not need to have carefully controlled environmental conditions. Following this process, the hologram is obtained at standard atmospheric conditions of pressure and temperature. Another advantage is that it is possible to obtain a hologram at a lower cost; furthermore, the property of applicability to any substrate that it has is remarkable.

  2. 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

  3. Integrated Surface Topography Characterization of Variously Polished Niobium for Superconducting Particle Accelerators

    Energy Technology Data Exchange (ETDEWEB)

    Hui Tian, Charles Reece, Michael Kelley, G. Ribeill

    2009-05-01

    As superconducting niobium radio-frequency (SRF) cavities approach fundamental material limits, there is increased interest in understanding the details of topographical influences on realized performance limitations. Micro-and nano-roughness are implicated in both direct geometrical field enhancements as well as complications of the composition of the 50 nm surface layer in which the super-currents flow. Interior surface chemical polishing (BCP/EP) to remove mechanical damage leaves surface topography, including pits and protrusions of varying sharpness. These may promote RF magnetic field entry, locally quenching superconductivity, so as to degrade cavity performance. A more incisive analysis of surface topography than the widely-used average roughness is needed. In this study, a power spectral density (PSD) approach based on Fourier analysis of surface topography data acquired by both stylus profilometry and atomic force microscopy (AFM) is being used to distinguish the scale-dependent smoothing effects. The topographical evolution of the Nb surface as a function of different steps of EP is reported, resulting in a novel qualitative and quantitative description of Nb surface topography.

  4. Selected indicators of the range and use of printed resources in Polish academic libraries

    OpenAIRE

    Górny, Mirosław; Jazdon, Artur; Nowak, Piotr

    1999-01-01

    Reports the results of a survey rating the amount and degree of the utilisation of printed materials in Polish academic libraries. The results which are presented by type (for example chemical, biological, technical libraries etc.) as well as by function (research libraries and libraries of educational institutions), concern the number of materials, including both books and periodicals. The authors include the amount of material in English as well as in other foreign l...

  5. Materials of the 39 Polish Seminar on Nuclear Magnetic Resonance and Its Applications - Abstracts

    International Nuclear Information System (INIS)

    The Report comprises abstracts of 78 communications presented during the 39 Polish Seminar on Nuclear Magnetic Resonance and Its Applications, held on November, 30 - December, 2006 in Cracow (PL). They cover a variety of research fields, including magnetic resonance imaging in vivo, applications of NMR spectroscopy to medical diagnosis, studies on molecular properties of different materials as well as quantum chemical calculations of NMR parameters

  6. 41 Polish Seminar on Nuclear Magnetic Resonance and Its Applications - Abstracts

    International Nuclear Information System (INIS)

    The Report consist of abstracts of 63 communications presented during the 41 Polish Seminar on Nuclear Magnetic Resonance and Its Applications, held on December 1-2, 2008 in Cracow. Presentations cover a variety of research fields, including magnetic resonance imaging in vivo, applications of NMR spectroscopy to medical diagnosis, studies on molecular properties of different materials as well as quantum chemical calculations of NMR parameters

  7. Effect of chemical and mechanical weed control on cassava yield, soil quality and erosion under cassava cropping system

    Science.gov (United States)

    Islami, Titiek; Wisnubroto, Erwin; Utomo, Wani

    2016-04-01

    Three years field experiments were conducted to study the effect of chemical and mechanical weed control on soil quality and erosion under cassava cropping system. The experiment were conducted at University Brawijaya field experimental station, Jatikerto, Malang, Indonesia. The experiments were carried out from 2011 - 2014. The treatments consist of three cropping system (cassava mono culture; cassava + maize intercropping and cassava + peanut intercropping), and two weed control method (chemical and mechanical methods). The experimental result showed that the yield of cassava first year and second year did not influenced by weed control method and cropping system. However, the third year yield of cassava was influence by weed control method and cropping system. The cassava yield planted in cassava + maize intercropping system with chemical weed control methods was only 24 t/ha, which lower compared to other treatments, even with that of the same cropping system used mechanical weed control. The highest cassava yield in third year was obtained by cassava + peanuts cropping system with mechanical weed control method. After three years experiment, the soil of cassava monoculture system with chemical weed control method possessed the lowest soil organic matter, and soil aggregate stability. During three years of cropping soil erosion in chemical weed control method, especially on cassava monoculture, was higher compared to mechanical weed control method. The soil loss from chemical control method were 40 t/ha, 44 t/ha and 54 t/ha for the first, second and third year crop. The soil loss from mechanical weed control method for the same years was: 36 t/ha, 36 t/ha and 38 t/ha. Key words: herbicide, intercropping, soil organic matter, aggregate stability.

  8. IDENTIFYING CHEMICALS FOR CUMULATIVE RISK ASSESSMENT USING COMMON MECHANISMS OF ACTION AND TOXICITY

    Science.gov (United States)

    Traditionally, potential health risk assessments from exposure to contaminated food, drinking water, or environmental media have been conducted on individual pesticides or chemicals in each medium of concern. However, humans are generally exposed to multiple chemicals and stress...

  9. Physico-chemical phenomena during mechanical thermal expression of water in low rank coal

    Energy Technology Data Exchange (ETDEWEB)

    Alan L. Chaffee; Yuli Aranto; Christian Bergins; Janine Hulston; Marc Marshall; Haruo Kumagai [Monash University, Vic. (Australia). School of Chemistry

    2007-07-01

    Mechanical thermal expression (MTE) is a non-evaporative method for water removal from low rank coal with typical processing conditions in the range 150-220{sup o}C and 10-20 MPa of applied mechanical pressure. Using a range of analytical methods, this study probes physico-chemical changes in the coal structure that occur as a result of MTE processing and, also, molecular dynamic behaviour under MTE conditions. Mercury intrusion porosimetry (MIP), after appropriately compensating for the coal's compressibility, showed that progressively harsher MTE conditions led to a reduction in the concentration of macropores and a concomitant increase in the concentration of mesopores. However, since MIP requires the use of dried samples, it does not facilitate the examination of 'as-received' samples. Using small angle X-ray scattering (SAXS) it was possible to examine the MTE products in both their wet and dry states enabling the pore volume reduction upon drying to be observed. Also, consideration of the SAXS and MIP results in combination, suggests that the abundance of 'closed' (meso)pores is reduced at higher MTE processing temperatures. The dynamic nature of coal molecular structure under MTE processing conditions has been probed for the first time using {sup 1}H-NMR transverse relaxation rate (T2) measurements. The data suggest that water exerts a 'plasticising' effect, enhancing the mobility of the coal structure at elevated temperature. This enhanced mobility (softening) presumably facilitates the reorganization of molecular structure, enabling the changes in porosity identified by MIP and SAXS. 22 refs., 8 figs., 1 tab.

  10. Thulium oxide fuel characterization study: Part 2, Environmental behavior and mechanical, thermal and chemical stability enhancement

    International Nuclear Information System (INIS)

    A study was performed of the correlation between fuel form stability and exposure environment of (temperature and atmosphere). 100% Tm2O3, 80% Tm2O3/20% Yb2O3 and 100% Yb2O3 wafers were subjected to air, dynamic vacuum and static vacuum at temperatures to 20000C for times to 100 hours. Results showed the Tm2O3/Yb2O3 cubic structure to be unaffected by elemental levels of iron, aluminum, magnesium and silicon and unaffected by the environmental conditions imposed on the wafers. A second task emphasized the optimization of the thermal, mechanical and chemical stability of Tm2O3 fuel forms. Enhancement was sought through process variable optimization and the addition of metal oxides to Tm2O3. CaO, TiO2 and Al2O3 were added to form a grain boundary precipitate to control fines generation. The presence of 1% additive was inadequate to depress the melting point of Tm2O3 or to change the cubic crystalline structure of Tm2O3/Yb2O3. Tm2O3/Yb2O3 wafers containing CaO developed a grain boundary phase that improved the resistance to fines generation. The presence of Yb2O3 did not appear to measurably influence behavior

  11. Experimental and Theoretical Study on the Surface Enhanced Raman Mechanism of Pristine and Chemically Doped Graphene

    Science.gov (United States)

    Feng, Simin; Dos Santos, Maria C.; Lu, Ruitao; Elias, Ana L.; Perea-Lopez, Nestor; Terrones, Mauricio

    2014-03-01

    It is demonstrated that graphene could be used as an efficient surface-enhanced Raman spectroscopy (SERS) substrate. Recently, our group has also shown that chemically doped graphene can improve the SERS signal of pristine graphene. Here we present an experimental and theoretical study on the SERS mechanism for both pristine (PG) and Nitrogen-doped graphene (NG). Large-area and highly-crystalline monolayer PG and NG sheets have been synthesized. Common molecules, such as Rhodamine B, Crystal Violet, Methylene Blue and Melamine were used as Raman probes using different laser excitation energies. It was observed that for each molecule, specific laser energy exhibits large intensity Raman signals when compared to others. More importantly, some signals can be detected even for concentrations as low as 10-8 M, which provides excellent molecular sensing properties. Then the system was modeled using DFT-B3LYP/6-31(d,p) and the Mulliken population analysis was used to calculate the net charge on the adsorbed molecules. By comparing the cases of PG and NG, our preliminary results suggest that stronger Raman enhancement of NG would likely be coming from the resonance of EF of graphene and the LUMO level of the adsorbed molecules.

  12. Chemical and biological mechanisms of phytochemical activation of Nrf2 and importance in disease prevention

    Science.gov (United States)

    Eggler, Aimee L.; Savinov, Sergey N.

    2016-01-01

    Plants are an incredibly rich source of compounds that activate the Nrf2 transcription factor, leading to upregulation of a battery of cytoprotective genes. This perspective surveys established and proposed molecular mechanisms of Nrf2 activation by phytochemicals with a special emphasis on a common chemical property of Nrf2 activators: the ability as “soft” electrophiles to modify cellular thiols, either directly or as oxidized biotransformants. In addition, the role of reactive oxygen/nitrogen species as secondary messengers in Nrf2 activation is discussed. While the uniquely reactive C151 of Keap1, an Nrf2 repressor protein, is highlighted as a key target of cytoprotective phytochemicals, also reviewed are other stress-responsive proteins, including kinases, which play non-redundant roles in the activation of Nrf2 by plant-derived agents. Finally, the perspective presents two key factors accounting for the enhanced therapeutic windows of effective phytochemical activators of the Keap1–Nrf2 axis: enhanced selectivity toward sensor cysteines and reversibility of addition to thiolate molecules. PMID:26855455

  13. Chemical and mechanical instabilities in high energy heavy-ion collisions

    Science.gov (United States)

    Gervino, G.; Lavagno, A.; Pigato, D.

    2015-07-01

    We investigate the possible thermodynamic instability in a warm and dense nuclear medium where a phase transition from nucleonic matter to resonance-dominated Δ-matter can take place. Such a phase transition is characterized by both mechanical instability (fluctuations on the baryon density) and by chemical-diffusive instability (fluctuations on the isospin concentration) in asymmetric nuclear matter. Similarly to the liquid-gas phase transition, the nucleonic and the Δ-matter phase have a different isospin density in the mixed phase. In the liquid-gas phase transition, the process of producing a larger neutron excess in the gas phase is referred to as isospin fractionation. A similar effects can occur in the nucleon-Δ matter phase transition due essentially to a Δ- excess in the Δ-matter phase in asymmetric nuclear matter. In this context, we study the hadronic equation of state by means of an effective quantum relativistic mean field model with the inclusion of the full octet of baryons, the Δ-isobar degrees of freedom, and the lightest pseudoscalar and vector mesons. Finally, we will investigate the presence of thermodynamic instabilities in a hot and dense nuclear medium where phases with different values of antibaryon-baryon ratios and strangeness content may coexist. Such a physical regime could be in principle investigated in the future high-energy compressed nuclear matter experiments where will make it possible to create compressed baryonic matter with a high net baryon density.

  14. Relaxation of the chemical bond skin chemisorption size matter ZTP mechanics H2O myths

    CERN Document Server

    Sun, Chang Q

    2014-01-01

    The aim of this book is to explore the detectable properties of a material to the parameters of bond and non-bond involved and to clarify the interdependence of various properties. This book is composed of four parts; Part I deals with the formation and relaxation dynamics of bond and non-bond during chemisorptions with uncovering of the correlation among the chemical bond, energy band, and surface potential barrier (3B) during reactions; Part II is focused on the relaxation of bonds between atoms with fewer neighbors than the ideal in bulk with unraveling of the bond order-length-strength (BOLS) correlation mechanism, which clarifies the nature difference between nanostructures and bulk of the same substance; Part III deals with the relaxation dynamics of bond under heating and compressing with revealing of rules on the temperature-resolved elastic and plastic properties of low-dimensional materials; Part IV is focused on the asymmetric relaxation dynamics of the hydrogen bond (O:H-O) and the anomalous behav...

  15. Do we need an Ad hoc chemical mechanism for Mexico City's photochemical smog?

    Science.gov (United States)

    Ruiz-Suárez, L. G.; Castro, T.; Mar, B.; Ruiz-Santoyo, M. E.; Cruz, X.

    Chemical mechanisms in mathematical models for air quality studies represent the synthesis of about 30 years of research in gas kinetics and atmospheric chemistry, and are able to represent, to a good extent, the chemistry of photochemical smog. However, due to the large amount of computer resources required by these models, different well-known approaches have been used in order to make them operative. In any of these approaches, a set of educated guesses is made, based upon the knowledge of the conditions under which the reactions occur and the competition between them, and upon the expected absolute and relative concentrations of the emitted reactive organic gases (ROG). Are those educated guesses applicable to Mexico City? Do we know enough how the prevalent conditions of temperature, total pressure, ultraviolet irradiation and water content in the atmosphere operate over the chemistry of photochemical smog? An answer to these questions has been attempted by performing variational analysis of selected hydrocarbons. Some results for n-butane, propene and trans-2-butene are shown; they show that under conditions of high reactivity, some assumptions may not be applicable to Mexico City. Also, the results serve to show the applicability of the method to preliminary reactivity studies.

  16. The physical-chemical characterization of mechanically-treated CFBC fly ash

    Energy Technology Data Exchange (ETDEWEB)

    Xiaoru Fu; Qin Li; Jianping Zhai; Guanghong Sheng; Feihu Li [Nanjing University, Nanjing (China). State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment

    2008-03-15

    The physical-chemical characteristics of mechanically-treated circulating fluidized bed combustion (CFBC) fly ash, such as 45 {mu}m sieve residue, granulometric distribution, water requirement, specific gravity, pH value, and mineralogical phases, were investigated. It was found that the grinding process can be divided into three stages. The increase in fineness of ground CFBC fly ash is very sharp in the first stage, then slows down in the second stage, and in the last stage it becomes almost invary. The water requirement decreases with prolonged grinding time, and slightly increases during the last stage of grinding. Ground CFBC fly ash shows a higher specific gravity due to the crushing of coarse particles and carbon particles. The pH of ground CFBC fly ash is greater than that of the original CFBC fly ash, indicating that ground samples react more rapidly with water. The mineralogical compositions remain unchanged with grinding, although the intensity of the crystalline phases decreases and the half peak width increases.

  17. A reliable control system for measurement on film thickness in copper chemical mechanical planarization system

    Science.gov (United States)

    Li, Hongkai; Qu, Zilian; Zhao, Qian; Tian, Fangxin; Zhao, Dewen; Meng, Yonggang; Lu, Xinchun

    2013-12-01

    In recent years, a variety of film thickness measurement techniques for copper chemical mechanical planarization (CMP) are subsequently proposed. In this paper, the eddy-current technique is used. In the control system of the CMP tool developed in the State Key Laboratory of Tribology, there are in situ module and off-line module for measurement subsystem. The in situ module can get the thickness of copper film on wafer surface in real time, and accurately judge when the CMP process should stop. This is called end-point detection. The off-line module is used for multi-points measurement after CMP process, in order to know the thickness of remained copper film. The whole control system is structured with two levels, and the physical connection between the upper and the lower is achieved by the industrial Ethernet. The process flow includes calibration and measurement, and there are different algorithms for two modules. In the process of software development, C++ is chosen as the programming language, in combination with Qt OpenSource to design two modules' GUI and OPC technology to implement the communication between the two levels. In addition, the drawing function is developed relying on Matlab, enriching the software functions of the off-line module. The result shows that the control system is running stably after repeated tests and practical operations for a long time.

  18. Influence of silane content and filler distribution on chemical-mechanical properties of resin composites

    Directory of Open Access Journals (Sweden)

    Tathy Aparecida XAVIER

    2015-01-01

    Full Text Available This study investigated the influence of silane concentration and filler size distribution on the chemical-mechanical properties of experimental composites. Experimental composites with silane contents of 0%, 1% and 3% (in relation to filler mass and composites with mixtures of barium glass particles (median size = 0.4, 1 and 2 μm and nanometric silica were prepared for silane and filler analyses, respectively. The degree of conversion (DC was analyzed by FTIR. Biaxial flexural strength (BFS was tested after 24-h or 90-d storage in water, and fracture toughness, after 24 h. The data were subjected to ANOVA and Tukey’s test (p = 0.05. The DC was not significantly affected by the silane content or filler distribution. The 0% silane group had the lowest immediate BFS, and the 90-d storage time reduced the strength of the 0% and 3% groups. BFS was not affected by filler distribution, and aging decreased the BFS of all the groups. Silanization increased the fracture toughness of both the 1% and 3% groups, similarly. Significantly higher fracture toughness was observed for mixtures with 2 μm glass particles. Based on the results, 3% silane content boosted the initial strength, but was more prone to degradation after water storage. Variations in the filler distribution did not affect BFS, but fracture toughness was significantly improved by increasing the filler size.

  19. Assessment of insulation degradation of I and C cables from chemical and mechanical measurements

    International Nuclear Information System (INIS)

    Instrumentation and control (I and C) cables used in nuclear power plants (NPPs) are exposed to various deteriorative environmental effects during their operational lifetime. The factors consisting of long-term irradiation (at rather low dose rates, in the presence of oxygen), and enhanced temperature eventually result in insulation degradation. Monitoring of the actual state of the cable insulation and the prediction of their residual service life consist of the measurement of the properties that are directly proportional to the functionality of the cables (usually the elongation at break is used as the critical parameter). In view of this, accelerated thermal and radiation ageing of I and C cable insulation materials have been carried out and the degradation due to thermal and radiation ageing has been assessed using oxidation induction time (OIT) and oxidation induction temperature (OITp) measurements by differential scanning calorimetry (DSC). As elongation at break (EAB) is considered to be a benchmark characterization technique for polymeric materials, tensile tests have also been carried out on these cable materials to measure EAB for correlating with DSC findings. The scanning electron microscopy (SEM) performed on fresh and aged samples support relatively good correlation between chemical and mechanical properties. (author)

  20. Recent achievements using chemical vapor composite silicon carbide (CVC SiC)

    Science.gov (United States)

    Goodman, William A.; Tanaka, Clifford

    2009-08-01

    This annual review documents our progress towards inexpensive mass production of silicon carbide mirrors and optical structures. Results are provided for a NASA Small Business Technology Transfer (STTR) X-Ray Mirror project. Trex partnered with the University of Alabama-Huntsville Center for Advanced Optics (UAH-CAO) to develop fabrication methods for polished cylindrical and conical chemical vapor composite (CVCTM) SiC mandrels. These mandrels are envisioned as pre-forms for the replication of fused silica x-ray optics to be eventually used in the International X-Ray Observatory (IXO). CVC SiCTM offers superior high temperature stability, thermal and mechanical performance and polishability required for this precision replication process. In this program, Trex fabricated prototype mandrels with design diameters of 10.5cm, 20cm and 45cm. UAH-CAO was Trex's university partner in this effort and worked on polishing and metrology of the unusual x-ray mandrel geometries. UAH-CAO successfully developed an innovative interferometric method for measuring the CVC SiCTM x-ray mandrels based on a precision cylindrical lens system. UAH-CAO also developed finishing and polishing methods for CVC SiCTM that utilized a Zeeko IRP200 computer controlled polishing tool. The three technologies key technologies demonstrated in this program (near net shape forming of CVC SiCTM mandrels, the x-ray mandrel metrology and free-form polishing capability on CVC SiCTM) could enable cost-effective manufacture of the x-ray mandrels required for the International X-Ray Observatory (IXO).

  1. Computational analysis of the mechanism of chemical reactions in terms of reaction phases: hidden intermediates and hidden transition States.

    Science.gov (United States)

    Kraka, Elfi; Cremer, Dieter

    2010-05-18

    Computational approaches to understanding chemical reaction mechanisms generally begin by establishing the relative energies of the starting materials, transition state, and products, that is, the stationary points on the potential energy surface of the reaction complex. Examining the intervening species via the intrinsic reaction coordinate (IRC) offers further insight into the fate of the reactants by delineating, step-by-step, the energetics involved along the reaction path between the stationary states. For a detailed analysis of the mechanism and dynamics of a chemical reaction, the reaction path Hamiltonian (RPH) and the united reaction valley approach (URVA) are an efficient combination. The chemical conversion of the reaction complex is reflected by the changes in the reaction path direction t(s) and reaction path curvature k(s), both expressed as a function of the path length s. This information can be used to partition the reaction path, and by this the reaction mechanism, of a chemical reaction into reaction phases describing chemically relevant changes of the reaction complex: (i) a contact phase characterized by van der Waals interactions, (ii) a preparation phase, in which the reactants prepare for the chemical processes, (iii) one or more transition state phases, in which the chemical processes of bond cleavage and bond formation take place, (iv) a product adjustment phase, and (v) a separation phase. In this Account, we examine mechanistic analysis with URVA in detail, focusing on recent theoretical insights (with a variety of reaction types) from our laboratories. Through the utilization of the concept of localized adiabatic vibrational modes that are associated with the internal coordinates, q(n)(s), of the reaction complex, the chemical character of each reaction phase can be identified via the adiabatic curvature coupling coefficients, A(n,s)(s). These quantities reveal whether a local adiabatic vibrational mode supports (A(n,s) > 0) or resists

  2. A coupled model between mechanical deformation and chemical diffusion: An explanation for the preservation of chemical zonation in plagioclase at high temperatures

    Science.gov (United States)

    Zhong, Xin; Vrijmoed, Johannes; Moulas, Evangelos; Tajcmanová, Lucie

    2016-04-01

    Compositional zoning in metamorphic minerals have been generally recognized as an important geological feature to decipher the metamorphic history of rocks. The observed chemical zoning of, e.g. garnet, is commonly interpreted as disequilibrium between the fractionated inner core and the surrounding matrix. However, chemically zoned minerals were also observed in high grade rocks (T>800 degree C) where the duration of metamorphic processes was independently dated to take several Ma. This implies that temperature may not be the only factor that controls diffusion timescales, and grain scale pressure variation was proposed to be a complementary factor that may significantly contribute to the formation and preservation of chemical zoning in high temperature metamorphic minerals [Tajcmanová 2013, 2015]. Here, a coupled model is developed to simulate viscous deformation and chemical diffusion. The numerical approach considers the conservation of mass, momentum, and a constitutive relation developed from equilibrium thermodynamics. A compressible viscoelastic rheology is applied, which associates the volumetric change triggered by deformation and diffusion to a change of pressure. The numerical model is applied to the chemically zoned plagioclase rim described by [Tajcmanová 2014]. The diffusion process operating during the plagioclase rim formation can lead to a development of a pressure gradient. Such a pressure gradient, if maintained during ongoing viscous relaxation, can lead to the preservation of the observed chemical zonation in minerals. An important dimensionless number, the Deborah number, is defined as the ratio between the Maxwell viscoelastic relaxation time and the characteristic diffusion time. It characterizes the relative influence between the maintenance of grain scale pressure variation and chemical diffusion. Two extreme regimes are shown: the mechanically-controlled regime (high Deborah number) and diffusion-controlled regime (low Deborah number

  3. Correlating the nanoscale mechanical and chemical properties of knockout mice bones

    Science.gov (United States)

    Kavukcuoglu, Nadire Beril

    Bone is a mineral-organic composite where the organic matrix is mainly type I collagen plus small amounts of non-collagenous proteins including osteopontin (OPN), osteocalcin (OC) and fibrillin 2 (Fbn2). Mature bone undergoes remodeling continually so new bone is formed and old bone resorbed. Uncoupling between the bone resorption and bone formation causes an overall loss of bone mass and leads to diseases like osteoporosis and osteopenia. These are characterized by structural deterioration of the bone tissue and an increased risk of fracture. The non-collagenous bone proteins are known to have a role in regulating bone turnover and to affect the structural integrity of bone. OPN and OC play a key role in bone resorption and formation, while absence of Fbn-2 causes a connective tissue disorder (congenital contractural arachnodactyly) and has been associated with decreased bone mass. In this thesis nanoindentation and Raman-microspectroscopy techniques were used to investigate and correlate the mechanical and chemical properties of cortical femoral bones from OPN deficient (OPN-/-), OC deficient (OC-/-) and Fbn-2 deficient (Fbn2-/-) mice and their age, sex and background matched wild-type controls (OPN+/+, OC+/+ and Fbn2+/+). For OPN the hardness (H) and elastic modulus (E) of under 12 week OPN-/- bones were significantly lower than for OPN+/+ bones, but Raman showed no significant difference. Mechanical properties of bones from mice older than 12 weeks were not significantly different with genotype. However, mineralization and crystallinity from >50 week OPN-/- bones were significantly higher than for OPN+/+ bones. Mechanical properties of OPN-/- bones showed no variation with age, but mineralization, crystallinity and type-B carbonate substitution increased for both genotypes. For OC-/- intra-bone analyses showed that the hardness and crystallinity of the bones were significantly higher, especially in the mid-cortical sections, compared to OC+/+ bones. Fbn2

  4. Abolished thermal and mechanical antinociception but retained visceral chemical antinociception induced by butorphanol in μ-opioid receptor knockout mice

    OpenAIRE

    Ide, Soichiro; Minami, Masabumi; Ishihara, Kumatoshi; Uhl, George R; Satoh, Masamichi; Sora, Ichiro; Ikeda, Kazutaka

    2008-01-01

    Butorphanol is hypothesized to induce analgesia via opioid pathways, although the precise mechanisms for its effects remain unknown. In this study, we investigated the role of the μ-opioid receptor (MOP) in thermal, mechanical, and visceral chemical antinociception induced by butorphanol using MOP knockout (KO) mice. Butorphanol-induced thermal antinociception, assessed by the hot-plate and tail-flick tests, was significantly reduced in heterozygous and abolished in homozygous MOP-KO mice com...

  5. 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.

  6. Polish Eastern Border as an External European Union Border

    OpenAIRE

    Mazurek, Tomasz; Barwiński, Marek

    2009-01-01

    1. Apart from Finnish-Russian border, Polish eastern border is one of the longest external European Union and Schengen Agreement land borders under the control of a single country. 2. For the last few years, Polish Government has significantly improved the infrastructure of Border Guard at the eastern border in order to prevent “flooding” of Europe by illegal immigrants and smuggled goods. 3. Despite this fact, Polish eastern border does not have sufficient infrastructure, especially wh...

  7. Polish migrant workers in the north: integration and xenophobia

    OpenAIRE

    Fitzgerald, Ian

    2014-01-01

    Polish migrant workers have moved from being a novel feature of many northern workplaces and communities to becoming resident in everyday life, with shops and businesses catering for their needs. The research undertaken here began in 2005 and is still continuing, more recently it has explored moral panics and the integration of Polish workers in the north. This recent work has been undertaken with a colleague from the Warsaw based Polish Academy of Sciences. The presentation will provide an i...

  8. Human Factors in Nuclear Power Engineering in Polish Conditions

    OpenAIRE

    Agnieszka Kaczmarek-Kacprzak; Martin Catlow

    2014-01-01

    The paper “Human factors in nuclear power engineering in Polish conditions” focuses on analysis of dynamics of preparing Polish society to build fi rst nuclear power plant in XXI century in Poland. Authors compare experience from constructing nuclear power plant Sizewell B (Great Britain) and Sizewell C, which is in preparation phase with polish nuclear power program. Paper includes aspects e.g. of creating nuclear safety culture and social opinion about investment. Human factors in nuclear p...

  9. Visible Light Activated Photocatalytic Water Polishing System Project

    Data.gov (United States)

    National Aeronautics and Space Administration — This proposal targets development of a LED light activated photocatalytic water polishing system that enables reduction of organic impurities (TOC and...

  10. Preparing polished crystal slices with high precision orientation

    DEFF Research Database (Denmark)

    Mathiesen, S. Ipsen; Gerward, Leif; Pedersen, O.

    1974-01-01

    A polishing procedure is described which utilizes a high precision Laue technique for crystal orientation. Crystal slices with their final polished surfaces parallel to a crystallographic plane within 0.02° can be prepared. ©1974 The American Institute of Physics......A polishing procedure is described which utilizes a high precision Laue technique for crystal orientation. Crystal slices with their final polished surfaces parallel to a crystallographic plane within 0.02° can be prepared. ©1974 The American Institute of Physics...

  11. Electrochemical mechanical micromachining based on confined etchant layer technique.

    Science.gov (United States)

    Yuan, Ye; Han, Lianhuan; Zhang, Jie; Jia, Jingchun; Zhao, Xuesen; Cao, Yongzhi; Hu, Zhenjiang; Yan, Yongda; Dong, Shen; Tian, Zhong-Qun; Tian, Zhao-Wu; Zhan, Dongping

    2013-01-01

    The confined etchant layertechnique (CELT) has been proved an effective electrochemical microfabrication method since its first publication at Faraday Discussions in 1992. Recently, we have developed CELT as an electrochemical mechanical micromachining (ECMM) method by replacing the cutting tool used in conventional mechanical machining with an electrode, which can perform lathing, planing and polishing. Through the coupling between the electrochemically induced chemical etching processes and mechanical motion, ECMM can also obtain a regular surface in one step. Taking advantage of CELT, machining tolerance and surface roughness can reach micro- or nano-meter scale.

  12. Mechanical properties of chemically bonded sand core materials dipped in sol-gel coating impregnated with filter

    DEFF Research Database (Denmark)

    Nwaogu, Ugochukwu Chibuzoh; Tiedje, Niels Skat

    2012-01-01

    A novel sol-gel coating impregnated with filter dust was applied on chemically bonded sand core materials by dipping. After curing, the strengths of the core materials were measured under uniaxial loading using a new strength testing machine (STM). The STM presents the loading history as a force......-displacement curve from which the mechanical properties of the materials are deduced. The fracture surfaces were examined using a stereomicroscope and a scanning electron microscope. From the results, the strengths of the core materials were slightly reduced by the coating in tensile and flexural modes, while...... the strengths were increased under compression. The mode of fracture of the chemically bonded sand core materials was observed to be intergranular through the binder. The stiffness of the chemically bonded sand core materials was determined. For better understanding of the mechanical properties...

  13. A review of the chemical and physical mechanisms of the storage stability of fast pyrolysis bio-oils

    Energy Technology Data Exchange (ETDEWEB)

    Diebold, J.P.

    1999-01-27

    Understanding the fundamental chemical and physical aging mechanisms is necessary to learn how to produce a bio-oil that is more stable during shipping and storage. This review provides a basis for this understanding and identifies possible future research paths to produce bio-oils with better storage stability.

  14. Plasma-enhanced chemical vapor deposited silicon oxynitride films for optical waveguide bridges for use in mechanical sensors

    DEFF Research Database (Denmark)

    Storgaard-Larsen, Torben; Leistiko, Otto

    1997-01-01

    In this paper the influence of RF power, ammonia flow, annealing temperature, and annealing time on the optical and mechanical properties of plasma-enhanced chemically vapor deposited silicon oxynitride films, is presented. A low refractive index (1.47 to 1.48) film having tensile stress has been...

  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. Pinning-depinning mechanism of the contact line during evaporation on chemically patterned surfaces: A lattice Boltzmann study

    CERN Document Server

    Li, Qing; Yan, H J

    2016-01-01

    In this paper, the pinning and depinning mechanism of the contact line during droplet evaporation on chemically stripe-patterned surfaces is numerically investigated using a thermal multiphase lattice Boltzmann (LB) model with liquid-vapor phase change. A local force balance in the context of diffuse interfaces is introduced to explain the equilibrium states of droplets on chemically patterned surfaces. It is shown that, when the contact line is pinned on a hydrophobic-hydrophilic boundary, different contact angles can be interpreted as the variation of the length of the contact line occupied by each component. The stick-slip-jump behavior of evaporating droplets on chemically patterned surfaces is well captured by the LB simulations. Particularly, a slow movement of the contact line is clearly observed during the stick (pinning) mode, which shows that the pinning of the contact line during droplet evaporation on chemically stripe-patterned surfaces is actually a dynamic pinning process and the dynamic equili...

  17. 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...

  18. Foreign direct investment in the Polish economy

    Directory of Open Access Journals (Sweden)

    Tomasz Gutowski

    2013-06-01

    Full Text Available Foreign Direct Investment (FDI plays an extraordinary and increasingly important role in global and local business. This type of investment gives the country a better position to prepare for rapidly changing economic conditions. Considering the external effects of FDI, it should be assumed that the most important one is coinvolvement in the development of a country in which they are located. In the Polish economy the value of foreign direct investment is very high and it is one of the most important causes of the economic growth.

  19. Elucidation of Mechanisms and Selectivities of Metal-Catalyzed Reactions using Quantum Chemical Methodology.

    Science.gov (United States)

    Santoro, Stefano; Kalek, Marcin; Huang, Genping; Himo, Fahmi

    2016-05-17

    Quantum chemical techniques today are indispensable for the detailed mechanistic understanding of catalytic reactions. The development of modern density functional theory approaches combined with the enormous growth in computer power have made it possible to treat quite large systems at a reasonable level of accuracy. Accordingly, quantum chemistry has been applied extensively to a wide variety of catalytic systems. A huge number of problems have been solved successfully, and vast amounts of chemical insights have been gained. In this Account, we summarize some of our recent work in this field. A number of examples concerned with transition metal-catalyzed reactions are selected, with emphasis on reactions with various kinds of selectivities. The discussed cases are (1) copper-catalyzed C-H bond amidation of indoles, (2) iridium-catalyzed C(sp(3))-H borylation of chlorosilanes, (3) vanadium-catalyzed Meyer-Schuster rearrangement and its combination with aldol- and Mannich-type additions, (4) palladium-catalyzed propargylic substitution with phosphorus nucleophiles, (5) rhodium-catalyzed 1:2 coupling of aldehydes and allenes, and finally (6) copper-catalyzed coupling of nitrones and alkynes to produce β-lactams (Kinugasa reaction). First, the methodology adopted in these studies is presented briefly. The electronic structure method in the great majority of these kinds of mechanistic investigations has for the last two decades been based on density functional theory. In the cases discussed here, mainly the B3LYP functional has been employed in conjunction with Grimme's empirical dispersion correction, which has been shown to improve the calculated energies significantly. The effect of the surrounding solvent is described by implicit solvation techniques, and the thermochemical corrections are included using the rigid-rotor harmonic oscillator approximation. The reviewed examples are chosen to illustrate the usefulness and versatility of the adopted methodology in

  20. Chemical characterization and ecotoxicity of three soil foaming agents used in mechanized tunneling

    Energy Technology Data Exchange (ETDEWEB)

    Baderna, Diego, E-mail: diego.baderna@marionegri.it [Laboratory of Environmental Chemistry and Toxicology, IRCCS – Istituto di Ricerche Farmacologiche Mario Negri, Via Giuseppe La Masa 19, 20156 Milan (Italy); Lomazzi, Eleonora [Laboratory of Environmental Chemistry and Toxicology, IRCCS – Istituto di Ricerche Farmacologiche Mario Negri, Via Giuseppe La Masa 19, 20156 Milan (Italy); Passoni, Alice [Unit of Analytical Instrumentation, IRCCS – Istituto di Ricerche Farmacologiche Mario Negri, Via Giuseppe La Masa 19, 20156 Milan (Italy); Pogliaghi, Alberto; Petoumenou, Maria Ifigeneia [Laboratory of Environmental Chemistry and Toxicology, IRCCS – Istituto di Ricerche Farmacologiche Mario Negri, Via Giuseppe La Masa 19, 20156 Milan (Italy); Bagnati, Renzo [Unit of Analytical Instrumentation, IRCCS – Istituto di Ricerche Farmacologiche Mario Negri, Via Giuseppe La Masa 19, 20156 Milan (Italy); Lodi, Marco [Laboratory of Environmental Chemistry and Toxicology, IRCCS – Istituto di Ricerche Farmacologiche Mario Negri, Via Giuseppe La Masa 19, 20156 Milan (Italy); Viarengo, Aldo; Sforzini, Susanna [Department of Sciences and Technological Innovation (DiSIT), University of Piemonte Orientale “A. Avogadro”, 15121 Alessandria (Italy); Benfenati, Emilio [Laboratory of Environmental Chemistry and Toxicology, IRCCS – Istituto di Ricerche Farmacologiche Mario Negri, Via Giuseppe La Masa 19, 20156 Milan (Italy); Fanelli, Roberto [Department of Environmental Health Sciences, IRCCS – Istituto di Ricerche Farmacologiche Mario Negri, Via Giuseppe La Masa 19, 20156 Milan (Italy)

    2015-10-15

    Highlights: • An integrated approach was applied to study three foaming agents. • Several compounds not reported on the safety data sheets were identified by HRMS. • Environmental impacts were investigated with a battery of biological assays. • An ecotoxicological ranking of the products was obtained. - Abstract: The construction of tunnels and rocks with mechanized drills produces several tons of rocky debris that are today recycled as construction material or as soil replacement for covering rocky areas. The lack of accurate information about the environmental impact of these excavated rocks and foaming agents added during the excavation process has aroused increasing concern for ecosystems and human health. The present study proposes an integrated approach to the assessment of the potential environmental impact of three foaming agents containing different anionic surfactants and other polymers currently on the market and used in tunnel boring machines. The strategy includes chemical characterization with high resolution mass spectrometry techniques to identify the components of each product, the use of in silico tools to perform a similarity comparison among these compounds and some pollutants already listed in regulatory frameworks to identify possible threshold concentrations of contamination, and the application of a battery of ecotoxicological assays to investigate the impact of each foaming mixture on model organisms of soil (higher plants and Eisenia andrei) and water communities (Daphnia magna). The study identified eleven compounds not listed on the material safety data sheets for which we have identified possible concentrations of contamination based on existing regulatory references. The bioassays allowed us to determine the no effect concentrations (NOAECs) of the three mixtures, which were subsequently used as threshold concentration for the product in its entirety. The technical mixtures used in this study have a different degree of toxicity

  1. Chemical characterization and ecotoxicity of three soil foaming agents used in mechanized tunneling.

    Science.gov (United States)

    Baderna, Diego; Lomazzi, Eleonora; Passoni, Alice; Pogliaghi, Alberto; Petoumenou, Maria Ifigeneia; Bagnati, Renzo; Lodi, Marco; Viarengo, Aldo; Sforzini, Susanna; Benfenati, Emilio; Fanelli, Roberto

    2015-10-15

    The construction of tunnels and rocks with mechanized drills produces several tons of rocky debris that are today recycled as construction material or as soil replacement for covering rocky areas. The lack of accurate information about the environmental impact of these excavated rocks and foaming agents added during the excavation process has aroused increasing concern for ecosystems and human health. The present study proposes an integrated approach to the assessment of the potential environmental impact of three foaming agents containing different anionic surfactants and other polymers currently on the market and used in tunnel boring machines. The strategy includes chemical characterization with high resolution mass spectrometry techniques to identify the components of each product, the use of in silico tools to perform a similarity comparison among these compounds and some pollutants already listed in regulatory frameworks to identify possible threshold concentrations of contamination, and the application of a battery of ecotoxicological assays to investigate the impact of each foaming mixture on model organisms of soil (higher plants and Eisenia andrei) and water communities (Daphnia magna). The study identified eleven compounds not listed on the material safety data sheets for which we have identified possible concentrations of contamination based on existing regulatory references. The bioassays allowed us to determine the no effect concentrations (NOAECs) of the three mixtures, which were subsequently used as threshold concentration for the product in its entirety. The technical mixtures used in this study have a different degree of toxicity and the predicted environmental concentrations based on the conditions of use are lower than the NOAEC for soils but higher than the NOAEC for water, posing a potential risk to the waters due to the levels of foaming agents in the muck. PMID:25917697

  2. Effect of Overlaid Material on Optical Transmission of Side-Polished Fiber Made by Wheel Side Polishing

    Institute of Scientific and Technical Information of China (English)

    Zhe Chen; Chun-He Bai

    2008-01-01

    The performance of optical power transmission through a side-polished fiber on which materials of different refractive indices were overlaid is investigated. The experiments show that the transmitted optical power through the side-polished fiber varies with the refractive index of the overlaid material. The result of our experiments fits well the theoretical calculation.Side-polished fiber manufactured by wheel polishing method can be used not only to control optical power transmission through the fiber core but also as a refractive index sensor.

  3. CO/sub 2/-laser polishing of fused silica surfaces for increased laser damage resistance at 1. 06. mu. m

    Energy Technology Data Exchange (ETDEWEB)

    Temple, P.A.; Milam, D.; Lowdermilk, W.H.

    1980-04-03

    Bare fused silica surfaces were prepared by subjecting the mechanically polished surface to a rastered cw CO/sub 2/ laser beam. Analysis shows that this processing causes: (a) removal of a uniform layer of fused silica; and (b) a probable re-fusing or healing of existing subsurface fractures. The fused silica removal rate is found to be a function of the laser intensity and scan rate. These surfaces are seen to have very low scatter and to be very smooth. In addition, they have exhibited entrance surface damage thresholds at 1.06 ..mu..m, and 1 nsec, which are substantially above those seen on the mechanically polished surface. When damage does occur, it tends to be at a few isolated points rather than the general uniform damage seen on the mechanicaly polished part. In addition to the damage results, we will discuss an observational technique used for viewing these surfaces which employs dark-field illumination.

  4. CO2-laser polishing of fused silica surfaces for increased laser damage resistance at 1.06 μm

    International Nuclear Information System (INIS)

    Bare fused silica surfaces were prepared by subjecting the mechanically polished surface to a rastered cw CO2 laser beam. Analysis shows that this processing causes: (a) removal of a uniform layer of fused silica; and (b) a probable re-fusing or healing of existing subsurface fractures. The fused silica removal rate is found to be a function of the laser intensity and scan rate. These surfaces are seen to have very low scatter and to be very smooth. In addition, they have exhibited entrance surface damage thresholds at 1.06 μm, and 1 nsec, which are substantially above those seen on the mechanically polished surface. When damage does occur, it tends to be at a few isolated points rather than the general uniform damage seen on the mechanicaly polished part. In addition to the damage results, we will discuss an observational technique used for viewing these surfaces which employs dark-field illumination

  5. Investigating Differences in Isoprene Oxidation Chemistry Between Gas-Phase Mechanisms Using a Constrained Chemical Box Model

    Science.gov (United States)

    Marvin, M. R.; Wolfe, G. M.; Salawitch, R. J.; Canty, T. P.; Hanisco, T. F.; Kaiser, J.; Keutsch, F. N.; Graus, M.; Warneke, C.; De Gouw, J. A.; Gilman, J.; Lerner, B. M.; Peischl, J.; Veres, P. R.; Min, K. E.; Holloway, J. S.; Aikin, K. C.; Ryerson, T. B.; Roberts, J. M.; Brown, S. S.; Pollack, I. B.; Hatch, C. D.; Lee, B. H.; Lopez-Hilfiker, F.; Thornton, J. A.; Diskin, G. S.; Sachse, G. W.; Huey, L. G.; Liu, X.; Wisthaler, A.; Mikoviny, T.; Wennberg, P. O.; St Clair, J.; Crounse, J.; Teng, A.

    2015-12-01

    Oxidation of isoprene by OH can significantly influence concentrations of important atmospheric pollutants such as ozone and secondary organic aerosols, but the chemistry that describes the relationships between these species is complex and not fully understood. Debate on the topic has led to differences in the isoprene oxidation schemes of several gas-phase chemical mechanisms currently applied in air chemistry models. We use the University of Washington Chemical Model (UWCMv3) to evaluate these mechanisms with respect to isoprene chemistry based on observations from the SENEX and SEAC4RS aircraft campaigns. The campaigns provide constraints on compounds measured over the Southeast United States, where isoprene concentrations are high and other conditions (e.g., NOx levels) vary widely. The payloads for both missions include observations of a wide range of isoprene oxidation products, which can provide insight into specific oxidation pathways. Analysis will focus on the characterization and comparison of isoprene oxidation chemistry for established gas-phase mechanisms that are prevalent in atmospheric modeling today, including the Carbon Bond mechanism (CB05 and CB6r2) and the Master Chemical Mechanism (versions 3.2 and 3.3).

  6. The chemical digestion of Ti6Al7Nb scaffolds produced by Selective Laser Melting reduces significantly ability of Pseudomonas aeruginosa to form biofilm.

    Science.gov (United States)

    Junka, Adam F; Szymczyk, Patrycja; Secewicz, Anna; Pawlak, Andrzej; Smutnicka, Danuta; Ziółkowski, Grzegorz; Bartoszewicz, Marzenna; Chlebus, Edward

    2016-01-01

    In our previous work we reported the impact of hydrofluoric and nitric acid used for chemical polishing of Ti-6Al-7Nb scaffolds on decrease of the number of Staphylococcus aureus biofilm forming cells. Herein, we tested impact of the aforementioned substances on biofilm of Gram-negative microorganism, Pseudomonas aeruginosa, dangerous pathogen responsible for plethora of implant-related infections. The Ti-6Al-7Nb scaffolds were manufactured using Selective Laser Melting method. Scaffolds were subjected to chemical polishing using a mixture of nitric acid and fluoride or left intact (control group). Pseudomonal biofilm was allowed to form on scaffolds for 24 hours and was removed by mechanical vortex shaking. The number of pseudomonal cells was estimated by means of quantitative culture and Scanning Electron Microscopy. The presence of nitric acid and fluoride on scaffold surfaces was assessed by means of IR and rentgen spetorscopy. Quantitative data were analysed using the Mann-Whitney test (P ≤ 0.05). Our results indicate that application of chemical polishing correlates with significant drop of biofilm-forming pseudomonal cells on the manufactured Ti-6Al-7Nb scaffolds ( p = 0.0133, Mann-Whitney test) compared to the number of biofilm-forming cells on non-polished scaffolds. As X-ray photoelectron spectroscopy revealed the presence of fluoride and nitrogen on the surface of scaffold, we speculate that drop of biofilm forming cells may be caused by biofilm-supressing activity of these two elements.

  7. The chemical digestion of Ti6Al7Nb scaffolds produced by Selective Laser Melting reduces significantly ability of Pseudomonas aeruginosa to form biofilm.

    Science.gov (United States)

    Junka, Adam F; Szymczyk, Patrycja; Secewicz, Anna; Pawlak, Andrzej; Smutnicka, Danuta; Ziółkowski, Grzegorz; Bartoszewicz, Marzenna; Chlebus, Edward

    2016-01-01

    In our previous work we reported the impact of hydrofluoric and nitric acid used for chemical polishing of Ti-6Al-7Nb scaffolds on decrease of the number of Staphylococcus aureus biofilm forming cells. Herein, we tested impact of the aforementioned substances on biofilm of Gram-negative microorganism, Pseudomonas aeruginosa, dangerous pathogen responsible for plethora of implant-related infections. The Ti-6Al-7Nb scaffolds were manufactured using Selective Laser Melting method. Scaffolds were subjected to chemical polishing using a mixture of nitric acid and fluoride or left intact (control group). Pseudomonal biofilm was allowed to form on scaffolds for 24 hours and was removed by mechanical vortex shaking. The number of pseudomonal cells was estimated by means of quantitative culture and Scanning Electron Microscopy. The presence of nitric acid and fluoride on scaffold surfaces was assessed by means of IR and rentgen spetorscopy. Quantitative data were analysed using the Mann-Whitney test (P ≤ 0.05). Our results indicate that application of chemical polishing correlates with significant drop of biofilm-forming pseudomonal cells on the manufactured Ti-6Al-7Nb scaffolds ( p = 0.0133, Mann-Whitney test) compared to the number of biofilm-forming cells on non-polished scaffolds. As X-ray photoelectron spectroscopy revealed the presence of fluoride and nitrogen on the surface of scaffold, we speculate that drop of biofilm forming cells may be caused by biofilm-supressing activity of these two elements. PMID:27150429

  8. Co-operation Amongst Polish Research Libraries

    Directory of Open Access Journals (Sweden)

    Ewa Dobrzyńska-Lankosz

    2007-11-01

    Full Text Available Polish research libraries have a long tradition of co-operating with one another, particularly when certain solutions require a collective effort. Co-operation can take place either at local, national or international level. In the past, we were able to observe close co-operation at the national level between libraries in similar disciplines (for instance, co-operation of groups of medical, technical and economics libraries. This form of co-operation has existed until today. Then, at the beginning of the 1990’s a new ‘configuration’ of library co-operation was initiated, that is, co-operation between libraries in various disciplines within one consortium aimed at choosing, purchasing and implementing the same integrated library system. The next step was co-operation undertaken within an inter-system consortium in order to fund a national union catalogue. This was an enormous enterprise, whose aim was to facilitate access to catalogue information on the collections of Polish research libraries and accelerate the process of cataloguing books. The National Union Catalogue NUKAT is based on shared cataloguing. At present, the catalogue is being created by 60 libraries, mainly academic.

  9. Impact of mechanical mowing and chemical treatment on phytosociological, pedochemical and biological parameters in roadside soils and vegetation.

    Science.gov (United States)

    Pellegrini, Elisa; Falcone, Lino; Loppi, Stefano; Lorenzini, Giacomo; Nali, Cristina

    2016-03-01

    Many chemical and non-chemical strategies have been applied to control weeds in agricultural and industrial areas. Knowledge regarding the effects of these methods on roadside vegetation is still poor. A 2-year field experiment was performed along a road located near Livorno (Tuscany, central Italy). Eight plots/strips were identified, of which four were subjected to periodical mechanical mowing and the remaining four were treated with a chemical herbicide based on glyphosate (the producer's recommended rates were used for the selective control of broad-leaved weeds). Our results clearly showed that roadside soil and vegetation are a significant reservoir of anthropogenic activities which have a strong negative effect on several phytosociological, pedochemical and biological parameters. Compared with conventional mechanical mowing, chemical treatment induced (i) a significant increase in organic matter in the upper plot layers (+18%), and (ii) a marked reduction in weed height throughout the entire period of the experiment. Irrespectively of the kind of treatment, no significance differences were detected in terms of (i) biological quality of soil (the abundance and diversity of arthropod communities did not change), and (ii) plant elemental content (bulk concentrations of analysed trace elements had a good fit within ranges of occurrence in the "reference plant"). The glyphosate partially controlled broad-leaved weeds and this moderate efficacy is dependent upon the season/time of application. In conclusion, the rational and sustainable use of chemical herbicides may be a useful tool for the management of roadside vegetation. PMID:26573685

  10. Deterministic Computer-Controlled Polishing Process for High-Energy X-Ray Optics

    Science.gov (United States)

    Khan, Gufran S.; Gubarev, Mikhail; Speegle, Chet; Ramsey, Brian

    2010-01-01

    A deterministic computer-controlled polishing process for large X-ray mirror mandrels is presented. Using tool s influence function and material removal rate extracted from polishing experiments, design considerations of polishing laps and optimized operating parameters are discussed

  11. Personality and temperamental features vs. quality of life of Polish seafarers.

    Science.gov (United States)

    Jeżewska, Maria; Leszczyńska, Irena; Grubman-Nowak, Marta

    2013-01-01

    In Poland seafarers are a significantly large occupational group and their work is highly burdening and hazardous. The environmental, physical, chemical, biological and psychosocial factors have a great impact on their quality of work and life. This report examines their quality of life and the relationship between quality of life, personality and temperament was evaluated. A total of 300 Polish seafarers took part in this study. Their average age is 44. Incorporated methods used were: WHOQOL-BREF, a survey for people working at sea, questionnaires: NEO-FFI and PTS. The results have shown that their quality of life is quite high. Polish seafarers show neuroticism below average and high extraversion. They are open, agreeable and scrupulous. Their power of stimulation and inhibition processes is correct.

  12. Analytic tendencies in modern Polish and Russian

    Directory of Open Access Journals (Sweden)

    Wojciech Sosnowski

    2015-11-01

    Full Text Available Analytic tendencies in modern Polish and RussianModern Polish and Russian are characterized by some features which demonstrate an increasing level of analitism. In the process of transformation from synthetic to analytical language, a crucial role is played by prepositional units. In this research, analitism is understood in a traditional way as a morphological and syntactic phenomenon. The fact that the synthetic structure of a language may, in some conditions, turn into an analytical one, as happened in the case of Bulgarian and Macedonian, has been intriguing linguists ever since, and has made me attempt to answer the question: What is the condition of modern Polish and Russian, which are languages with a rich literary tradition and solid grammatical norms, which belong to a group of synthetic languages? The analytical tendencies in morphology include the following: a decrease in the number of cases in all inflected parts of speech; a more frequent use of uninflected nouns and adjectives; the growing importance of nouns with common gender, and, in particular, the use of forms of masculine gender to depict feminine gender; differences in expressing collectiveness in a group of nouns (using collective meaning for forms that have singular meaning; substituting case forms with prepositions; substituting case forms with subordinate clauses; substituting case forms with “helper” words. Analytical tendencies in the area of numeral functioning include: substituting inflected forms of ordinal numerals with cardinal ones; the gradual disappearing inflection of numerals; confusing the forms of noun cases after numerals; the disappearing declination of collective numerals; displacing other cases with so-called simple cases; changing the syntactical position which the numeral should be inflected in; abandoning the declination of first elements of collective numerals. During the study of analytic tendencies in morphology, it was necessary to examine

  13. POLISHING EFFLUENT FROM A PERCHLORATE-REDUCING ANAEROBIC BIOLOGICAL CONTACTOR

    Science.gov (United States)

    The U.S. Environmental Protection Agency undertook at 3 ½ year pilot-scale biological perchlorate treatment study that included two long (311 and 340 days) examinations of anaerobic effluent polishing. The polishing system consisted of hydrogen peroxide addition and aeration, fo...

  14. 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

  15. Can a global model chemical mechanism reproduce NO, NO2, and O3 measurements above a tropical rainforest?

    Directory of Open Access Journals (Sweden)

    C. N. Hewitt

    2009-12-01

    Full Text Available A cross-platform field campaign, OP3, was conducted in the state of Sabah in Malaysian Borneo between April and July of 2008. Among the suite of observations recorded, the campaign included measurements of NOx and O3–crucial outputs of any model chemistry mechanism. We describe the measurements of these species made from both the ground site and aircraft. We examine the output from the global model p-TOMCAT at two resolutions for this location during the April campaign period. The models exhibit reasonable ability in capturing the NOx diurnal cycle, but ozone is overestimated. We use a box model containing the same chemical mechanism to explore the weaknesses in the global model and the ability of the simplified global model chemical mechanism to capture the chemistry at the rainforest site. We achieve a good fit to the data for all three species (NO, NO2, and O3, though the model is much more sensitive to changes in the treatment of physical processes than to changes in the chemical mechanism. Indeed, without some parameterization of the nighttime boundary layer-free troposphere mixing, a time dependent box model will not reproduce the observations. The final simulation uses this mixing parameterization for NO and NO2 but not O3, as determined by the vertical structure of each species, and matches the measurements well.

  16. Effect of layering sequence and chemical treatment on the mechanical properties of woven kenaf–aramid hybrid laminated composites

    International Nuclear Information System (INIS)

    Highlights: • The mechanical properties of woven kenaf/Kevlar hybrid composites were analysed. • The layering sequences affect the mechanical properties of hybrid composites. • Treated kenaf improves the mechanical properties of hybrid composites. - Abstract: This work aims to evaluate the effect of layering sequence and chemical treatment on mechanical properties of woven kenaf–Kevlar composites. Woven kenaf–aramid hybrid laminated composites fabricated through hand lay-up techniques by arranging woven kenaf and Kevlar fabrics in different layering sequences and by using treated kenaf mat. To evaluate the effect of chemical treatment on hybrid composites, the woven kenaf mat was treated with 6% sodium hydroxide (NaOH) diluted solution and compared mechanical properties with untreated kenaf hybrid composites. Results shows that the tensile properties of hybrid composites improved in 3-layer composites compared to 4-layer composites. Hybrid composite with Kevlar as outer layers display a better mechanical properties as compared to other hybrid composites. Tensile and flexural properties of treated hybrid composites are better than non-treated hybrid composites. The fractured surface of hybrid composites was investigated by scanning electron microscopy. This study is a part of exploration of potential application of the hybrid composite in high velocity impact application

  17. Mechanism of Methane Chemical Looping Combustion with Hematite Promoted with CeO 2

    Energy Technology Data Exchange (ETDEWEB)

    Miller, Duane D.; Siriwardane, Ranjani

    2013-08-15

    Chemical looping combustion (CLC) is a promising technology for fossil fuel combustion that produces sequestration-ready CO{sub 2} stream, reducing the energy penalty of CO{sub 2} separation from flue gases. An effective oxygen carrier for CLC will readily react with the fuel gas and will be reoxidized upon contact with oxygen. This study investigated the development of a CeO{sub 2}-promoted Fe{sub 2}O{sub 3}-hematite oxygen carrier suitable for the methane CLC process. Composition of CeO{sub 2} is between 5 and 25 wt % and is lower than what is generally used for supports in Fe{sub 2}O{sub 3} carrier preparations. The incorporation of CeO{sub 2} to the natural ore hematite strongly modifies the reduction behavior in comparison to that of CeO{sub 2} and hematite alone. Temperature-programmed reaction studies revealed that the addition of even 5 wt % CeO{sub 2} enhances the reaction capacity of the Fe{sub 2}O{sub 3} oxygen carrier by promoting the decomposition and partial oxidation of methane. Fixed-bed reactor data showed that the 5 wt % cerium oxides with 95 wt % iron oxide produce 2 times as much carbon dioxide in comparison to the sum of carbon dioxide produced when the oxides were tested separately. This effect is likely due to the reaction of CeO{sub 2} with methane forming intermediates, which are reactive for extracting oxygen from Fe{sub 2}O{sub 3} at a considerably faster rate than the rate of the direct reaction of Fe{sub 2}O{sub 3} with methane. These studies reveal that 5 wt % CeO{sub 2}/Fe{sub 2}O{sub 3} gives stable conversions over 15 reduction/oxidation cycles. Lab-scale reactor studies (pulsed mode) suggest the methane reacts initially with CeO{sub 2} lattice oxygen to form partial oxidation products (CO + H{sub 2}), which continue to react with oxygen from neighboring Fe{sub 2}O{sub 3}, leading to its complete oxidation to form CO{sub 2}. The reduced cerium oxide promotes the methane decomposition reaction to form C + H{sub 2}, which continue to

  18. Toxicological Mechanism of Endocrine Disrupting Chemicals:Is Estrogen Receptor Involved?

    OpenAIRE

    Jeung, Eui-Bae; Choi, Kyung-Chul

    2010-01-01

    Endocrine disrupting chemicals (EDCs) have been shown to interfere with physiological systems, i.e., adversely affecting hormone balance (endocrine system) , or disrupting normal function, in the female and male reproductive organs. Although endocrine disruption is a global concern for human health, its impact and significance and the screening strategy for detecting these synthetic or man-made chemicals are not clearly understood in female and male reproductive functions. Thus, in this revie...

  19. Semiempirical Predictions of Chemical Degradation Reaction Mechanisms of CL-20 as Related to Molecular Structure

    Energy Technology Data Exchange (ETDEWEB)

    Qasim, Mohammad M.; Furey, John; Fredrickson, Herbert L.; Szecsody, Jim E.; Mcgrath, Chris J.; Bajpai, Rakesh

    2004-10-01

    Quantum mechanical methods and force field molecular mechanics were used to characterize cage cyclic nitramines and to predict environmental degradation mechanisms. Due to structural similarities it is predicted that, under homologous circumstances, the major environmental RDX degradation pathways should also be effective for CL-20 and similar cyclic nitramines.

  20. Mechanism and Optimal Application of Chemical Additives for Accelerating Early Strength of Lime-flyash Stabilized Soils

    Institute of Scientific and Technical Information of China (English)

    JIANG Zengguo; ZHAO Yuan

    2005-01-01

    To accelerate the early strength of lime-flyash stabilized soil for extending its further uses in highway and shortening highway construction time, five kinds of chemical additives were chosen on the basis of mechanism analysis of accelerating early strength in highway as a semi-rigid base material, and a series of experiments about the effect of different kinds of additives and quantity on the early strength of the stabilized soil were tested. The results show that chemical additives can efficiently improve the early strength of lime-flyash stabilized soil both the 7 d and 28d, and the optimum quantity for above chemical additive is 1.5%-2.5% approximately.Some suggestions for the practical construction were also proposed.