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Sample records for based chemically modified

  1. Chemical sensors based on molecularly modified metallic nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Haick, Hossam [Department of Chemical Engineering and Russell Berrie Nanotechnology Institute, Technion - Israel Institute of Technology, Haifa 32000 (Israel)

    2007-12-07

    This paper presents a concise, although admittedly non-exhaustive, didactic review of some of the main concepts and approaches related to the use of molecularly modified metal nanoparticles in or as chemical sensors. This paper attempts to pull together different views and terminologies used in sensors based on molecularly modified metal nanoparticles, including those established upon electrochemical, optical, surface Plasmon resonance, piezoelectric and electrical transduction approaches. Finally, this paper discusses briefly the main advantages and disadvantages of each of the presented class of sensors. (review article)

  2. Detecting Chemically Modified DNA Bases Using Surface Enhanced Raman Spectroscopy.

    Science.gov (United States)

    Barhoumi, Aoune; Halas, Naomi J

    2011-12-15

    Post-translational modifications of DNA- changes in the chemical structure of individual bases that occur without changes in the DNA sequence- are known to alter gene expression. They are believed to result in frequently deleterious phenotypic changes, such as cancer. Methylation of adenine, methylation and hydroxymethylation of cytosine, and guanine oxidation are the primary DNA base modifications identified to date. Here we show it is possible to use surface enhanced Raman spectroscopy (SERS) to detect these primary DNA base modifications. SERS detection of modified DNA bases is label-free and requires minimal additional sample preparation, reducing the possibility of additional chemical modifications induced prior to measurement. This approach shows the feasibility of DNA base modification assessment as a potentially routine analysis that may be further developed for clinical diagnostics.

  3. Chemical composition of silica-based biocidal modifier

    Directory of Open Access Journals (Sweden)

    Grishina Anna Nikolaevna

    2016-11-01

    Full Text Available Increase of the amount of fungi spores and micotixines causes the increase in the number of different diseases. Because of this, ensuring the biological safety in buildings is becoming more and more important today. The preferred way to guarantee the biological safety of a building is to employ modern building materials that prevent the settlement of the fungi colonies on the inner surfaces of walls. Such building materials can be produced using novel biocidal modifiers that allow controlling the number of microorganisms on the surface and in the bulk of a composite construction. The precipitation product of zinc hydrosilicates and sodium sulfate is one of the mentioned modifiers. Till now, the exact chemical composition of such precipitation product is controversial; it is obvious, though, that the efficacy of the biocidal modifier is mostly determined by the type of the copper compounds. In the present work an integrated approach is used for the investigation of the chemical composition of the biocidal modifier. Such an approach consists in the examination of the modifier’s composition by means of different, yet complementary, research methods: X-ray diffraction, infrared spectroscopy and DTA. It is shown that the chemical composition of the modifier mainly depends on the amount of precipitant. X-ray diffraction reveals that the major part of the modifier is represented by amorphous phase. Along with the increase of the precipitant’s amount the crystalline phase Zn4SO4(OH6•xH2O formation takes place. Such a crystalline phase is not appropriate as a component of the biocidal modifier. Another two methods - DTA and IR spectroscopy - reveal that the amorphous phase consists essentially of zinc hydrosilicates.

  4. CHEMICALLY MODIFIED FIELD-EFFECT TRANSISTORS - POTENTIOMETRIC AG+ SELECTIVITY OF PVC MEMBRANES BASED ON MACROCYCLIC THIOETHERS

    NARCIS (Netherlands)

    BRZOZKA, Z; COBBEN, PLHM; REINHOUDT, DN; EDEMA, JJH; KELLOGG, RM

    1993-01-01

    A chemically modified field-effect transistor (CHEMFET) with satisfactory Ag+ selectivity is described. The potentiometric Ag+ selectivities of CHEMFETs with plasticized PVC membranes based on macrocyclic thioethers have been determined. All the macrocyclic thioethers tested showed silver response a

  5. Reference field effect transistor based on chemically modified ISFETs

    NARCIS (Netherlands)

    Skowronska-Ptasinska, Maria; Wal, van der Peter D.; Berg, van den Albert; Bergveld, Piet; Sudhölter, Ernst J.R.; Reinhoudt, David N.

    1990-01-01

    Different hydrophobic polymers were used for chemical modification of ion-sensitive field effect transistors (ISFETs) in order to prepare a reference FET (REFET). Chemical attachment of the polymer to the ISFET gate results in a long lifetime of the device. Properties of polyacrylate (polyACE) REFET

  6. Chemical Sensors Based on IR Spectroscopy and Surface-Modified Waveguides

    Science.gov (United States)

    Lopez, Gabriel P.; Niemczyk, Thomas

    1999-01-01

    Sol-gel processing techniques have been used to apply thin porous films to the surfaces of planar infrared (IR) waveguides to produce widely useful chemical sensors. The thin- film coating serves to diminish the concentration of water and increase the concentration of the analyte in the region probed by the evanescent IR wave. These porous films are composed of silica, and therefore, conventional silica surface modification techniques can be used to give the surface a specific functional character. The sol-gel film was surface-modified to make the film highly hydrophobic. These sensors were shown to be capable of detecting non-polar organic analytes, such as benzonitrile, in aqueous solution with detection limits in the ppb range. Further, these porous sol-gel structures allow the analytes to diffuse into and out of the films rapidly, thus reaching equilibrium in less than ten seconds. These sensors are unique because of the fact that their operation is based on the measurement of an IR absorption spectrum. Thus, these sensors are able to identify the analytes as well as measure concentration with high sensitivity. These developments have been documented in previous reports and publications. Recently, we have also targeted detection of the polar organic molecules acetone and isopropanol in aqueous solution. Polar organics are widely used in industrial and chemical processes, hence it is of interest to monitor their presence in effluents or decontamination process flows. Although large improvements in detection limits were expected with non-polar organic molecules in aqueous solutions using very hydrophobic porous sol-gel films on silicon attenuated total reflectance (Si ATR) waveguides, it was not as clear what the detection enhancements might be for polar organic molecules. This report describes the use of modified sol-gel-coated Si ATR sensors for trace detection and quantitation of small polar organic molecules in aqueous solutions. The detection of both acetone

  7. Improved actuation strain of PDMS-based DEA materials chemically modified with softening agents

    Science.gov (United States)

    Biedermann, Miriam; Blümke, Martin; Wegener, Michael; Krüger, Hartmut

    2015-04-01

    Dielectric elastomer actuators (DEAs) are smart materials that gained much in interest particularly in recent years. One active field of research is the improvement of their properties by modification of their structural framework. The object of this work is to improve the actuation properties of polydimethylsiloxane (PDMS)-based DEAs by covalent incorporation of mono-vinyl-terminated low-molecular PDMS chains into the PDMS network. These low-molecular units act as a kind of softener within the PDMS network. The loose chain ends interfere with the network formation and lower the network's density. PDMS films with up to 50wt% of low-molecular PDMS additives were manufactured and the chemical, mechanical, electrical, and electromechanical properties of these novel materials were investigated.

  8. Multifunctional hybrid nanocomposites based on carbon nanotubes and chemically modified graphene

    OpenAIRE

    Bosch Navarro, Concepcion

    2013-01-01

    La Tesis trata del desarrollo de materiales híbridos multifuncionales basados en nanotubos de carbono y grafeno con interés en magnetismo molecular y electrónica molecular This Thesis deals with the chemistry and development of new hybrid multifunctional systems based on carbon nanotubes (CNTs) and graphene (G). To introduce both types of carbon nanoforms a brief historical overview of these systems has been briefly given at the Preface. Next and prior to the presentation of ...

  9. Nanobiosensors Based on Chemically Modified AFM Probes: A Useful Tool for Metsulfuron-Methyl Detection

    Directory of Open Access Journals (Sweden)

    Fabio L. Leite

    2013-01-01

    Full Text Available The use of agrochemicals has increased considerably in recent years, and consequently, there has been increased exposure of ecosystems and human populations to these highly toxic compounds. The study and development of methodologies to detect these substances with greater sensitivity has become extremely relevant. This article describes, for the first time, the use of atomic force spectroscopy (AFS in the detection of enzyme-inhibiting herbicides. A nanobiosensor based on an atomic force microscopy (AFM tip functionalised with the acetolactate synthase (ALS enzyme was developed and characterised. The herbicide metsulfuron-methyl, an ALS inhibitor, was successfully detected through the acquisition of force curves using this biosensor. The adhesion force values were considerably higher when the biosensor was used. An increase of ~250% was achieved relative to the adhesion force using an unfunctionalised AFM tip. This considerable increase was the result of a specific interaction between the enzyme and the herbicide, which was primarily responsible for the efficiency of the nanobiosensor. These results indicate that this methodology is promising for the detection of herbicides, pesticides, and other environmental contaminants.

  10. Properties of Thermosets Derived from Chemically Modified Triglycerides and Bio-Based Comonomers

    Directory of Open Access Journals (Sweden)

    Evan S. Beach

    2013-12-01

    Full Text Available A series of materials was prepared by curing acrylated epoxidized soybean oil (AESO and dibutyl itaconate (DBI or ethyl cinnamate (EC comonomers to provide examples of thermosets with a high proportion of bio-based carbon, in accordance with the principles of green chemistry. The comonomers, representative of cellulose-derived (DBI or potentially lignin-derived (EC raw materials, were tested at levels of 25%, 33%, and 50% by mass and the resulting products were characterized by infrared spectroscopy, thermogravimetric analysis, and dynamic mechanical analysis. Both DBI and EC were incorporated into the thermosets to a high extent (>90% at all concentrations tested. The AESO-DBI and AESO-EC blends showed substantial degradation at 390–400 °C, similar to pure AESO. Glass transition temperatures decreased as comonomer content increased; the highest Tg of 41.4 °C was observed for AESO-EC (3:1 and the lowest Tg of 1.4 °C was observed for AESO-DBI (1:1. Accordingly, at 30 °C the storage modulus values were highest for AESO-EC (3:1, 37.0 MPa and lowest for AESO-DBI (1:1, 1.5 MPa.

  11. Nanobiosensors Based on Chemically Modified AFM Probes: A Useful Tool for Metsulfuron-Methyl Detection

    Science.gov (United States)

    da Silva, Aline C.N.; Deda, Daiana K.; da Róz, Alessandra L.; Prado, Rogilene A.; Carvalho, Camila C.; Viviani, Vadim; Leite, Fabio L.

    2013-01-01

    The use of agrochemicals has increased considerably in recent years, and consequently, there has been increased exposure of ecosystems and human populations to these highly toxic compounds. The study and development of methodologies to detect these substances with greater sensitivity has become extremely relevant. This article describes, for the first time, the use of atomic force spectroscopy (AFS) in the detection of enzyme-inhibiting herbicides. A nanobiosensor based on an atomic force microscopy (AFM) tip functionalised with the acetolactate synthase (ALS) enzyme was developed and characterised. The herbicide metsulfuron-methyl, an ALS inhibitor, was successfully detected through the acquisition of force curves using this biosensor. The adhesion force values were considerably higher when the biosensor was used. An increase of ∼250% was achieved relative to the adhesion force using an unfunctionalised AFM tip. This considerable increase was the result of a specific interaction between the enzyme and the herbicide, which was primarily responsible for the efficiency of the nanobiosensor. These results indicate that this methodology is promising for the detection of herbicides, pesticides, and other environmental contaminants. PMID:23348034

  12. Interpenetrating polymer networks based on polyol modified castor oil polyurethane and poly(2-hydroxyethylmethacrylate): Synthesis, chemical, mechanical and thermal properties

    Indian Academy of Sciences (India)

    K Prashantha; K Vasanth Kumar Pai; B S Sherigara; S Prasannakumar

    2001-10-01

    Interpenetrating polymer networks (IPNs) of glycerol modified castor oil polyurethane (GC–PU) and poly[2-hydroxyethylmethacrylate] (PHEMA) were synthesized using benzoyl peroxide as initiator and N,N-methylene bis acrylamide as crosslinker. GC–PU/PHEMA interpenetrating polymer networks were obtained by transfer moulding. These were characterized with respect to their resistance to chemical reagents and mechanical properties such as tensile strength, per cent elongation and shore A hardness. Differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) were undertaken for thermal characterization. The changes in NCO/OH ratio and GC–PU/PHEMA composition on the properties of the IPNs were studied.

  13. Development of a virus concentration method using lanthanum-based chemical flocculation coupled with modified membrane filtration procedures.

    Science.gov (United States)

    Zhang, Yanyan; Riley, Lela K; Lin, Mengshi; Purdy, Gregory A; Hu, Zhiqiang

    2013-06-01

    Direct membrane filtration is often used to concentrate viruses in water but it may suffer from severe membrane fouling and clogging. Here, a lanthanum-based flocculation method coupled with modified membrane filtration procedures was developed and evaluated to detect viruses in large volume (40 L) water samples. The lanthanum-based flocculation method could easily reduce the water sample volume by a factor of 40. Additional volume reduction was achieved by a two-step membrane filtration approach. First, selected membrane filters (including 1MDS electropositive filters and nitrocellulose electronegative filters-Millipore HATF filters) were used to reduce water sample volume further and compare their efficiencies in virus recovery. The Mg²⁺-modified HATF membrane performed better on MS2 retention with an average virus recovery of 83.4% (±4.5% [standard deviation]). After HATF membrane filtration and elution, centrifugal ultrafiltration through a 30 kDa cut-off membrane resulted in an overall concentration factor of 20,000. Results from the infectivity assay showed that the MS2 recovery efficiencies from the NanoCeram- and 1MDS-based direct filtration and the lanthanum-based concentration coupled with the modified filtration procedure were 10.1% (±1.0%), 3.3% (±0.1%), and 17.5% (±1.1%), respectively. Results from the PCR analysis showed that the virus recoveries of the lanthanum-based method were 20.6% (±2.9%) and 19.5% (±3.4%) for MS2 and adenovirus, respectively, while no adenovirus could be detected through the NanoCeram- and 1MDS-based direct filtration. The lanthanum-based concentration method coupled with modified membrane filtration procedures is therefore a promising method for detecting waterborne viruses.

  14. Chemical stability and osteogenic activity of plasma-sprayed boron-modified calcium silicate-based coatings.

    Science.gov (United States)

    Lu, Xiang; Li, Kai; Xie, Youtao; Huang, Liping; Zheng, Xuebin

    2016-11-01

    In recent years, CaSiO3 bio-ceramic coatings have attracted great attention because of their good bioactivity. However, their high degradation rates in physiological environment restrict their practical applications. In this work, boron-modified CaSiO3 ceramic (Ca11Si4B2O22, B-CS) coating was developed on Ti substrates by plasma-spraying technique attempting to obtain enhanced chemical stability and osteogenic activity. The B-CS coating possessed significantly increased chemical stability due to the introduction of boron and consequently the modified crystal structure, while maintaining good bioactivity. Scanning electron microscope and immunofluorescence studies showed that better cellular adhesion and extinctive filopodia-like processes were observed on the B-CS coating. Compared with the pure CaSiO3 (CS) coating, the B-CS coating promoted MC3T3-E1 cells attachment and proliferation. In addition, enhanced collagen I (COL-I) secretion, alkaline phosphatase activity, and extracellular matrix mineralization levels were detected from the B-CS coating. According to RT-PCR results, notable up-regulation expressions of mineralized tissue-related genes, such as runt-related transcription factor 2 (Runx2), bone sialoprotein and osteocalcin, and bone morphogenetic protein 7 (BMP-7) were observed on the B-CS coating compared with the CS coating. The above results suggested that Ca11Si4B2O22 coatings possess excellent osteogenic activity and might be a promising candidate for orthopedic applications.

  15. Chemically-Modified Cellulose Paper as a Microstructured Catalytic Reactor

    Directory of Open Access Journals (Sweden)

    Hirotaka Koga

    2015-01-01

    Full Text Available We discuss the successful use of chemically-modified cellulose paper as a microstructured catalytic reactor for the production of useful chemicals. The chemical modification of cellulose paper was achieved using a silane-coupling technique. Amine-modified paper was directly used as a base catalyst for the Knoevenagel condensation reaction. Methacrylate-modified paper was used for the immobilization of lipase and then in nonaqueous transesterification processes. These catalytic paper materials offer high reaction efficiencies and have excellent practical properties. We suggest that the paper-specific interconnected microstructure with pulp fiber networks provides fast mixing of the reactants and efficient transport of the reactants to the catalytically-active sites. This concept is expected to be a promising route to green and sustainable chemistry.

  16. Quality of chemically modified hemp fibers.

    Science.gov (United States)

    Kostic, Mirjana; Pejic, Biljana; Skundric, Petar

    2008-01-01

    Hemp fibers are very interesting natural material for textile and technical applications now. Applying hemp fibers to the apparel sector requires improved quality fibers. In this paper, hemp fibers were modified with sodium hydroxide solutions (5% and 18% w/v), at room and boiling temperature, for different periods of time, and both under tension and slack, in order to partially extract noncellulosic substances, and separate the fiber bundles. The quality of hemp fibers was characterised by determining their chemical composition, fineness, mechanical and sorption properties. The modified hemp fibers were finer, with lower content of lignin, increased flexibility, and in some cases tensile properties were improved. An original method for evaluation of tensile properties of hemp fibers was developed.

  17. Encoded libraries of chemically modified peptides.

    Science.gov (United States)

    Heinis, Christian; Winter, Greg

    2015-06-01

    The use of powerful technologies for generating and screening DNA-encoded protein libraries has helped drive the development of proteins as pharmaceutical ligands. However the development of peptides as pharmaceutical ligands has been more limited. Although encoded peptide libraries are typically several orders of magnitude larger than classical chemical libraries, can be more readily screened, and can give rise to higher affinity ligands, their use as pharmaceutical ligands is limited by their intrinsic properties. Two of the intrinsic limitations include the rotational flexibility of the peptide backbone and the limited number (20) of natural amino acids. However these limitations can be overcome by use of chemical modification. For example, the libraries can be modified to introduce topological constraints such as cyclization linkers, or to introduce new chemical entities such as small molecule ligands, fluorophores and photo-switchable compounds. This article reviews the chemistry involved, the properties of the peptide ligands, and the new opportunities offered by chemical modification of DNA-encoded peptide libraries.

  18. Electrochemical behavior of folic acid at calixarene based chemically modified electrodes and its determination by adsorptive stripping voltammetry

    Energy Technology Data Exchange (ETDEWEB)

    Vaze, Vishwanath D. [Department of Chemistry, University of Mumbai, Vidyanagari, Santacruz (East), Mumbai 400098 (India); Srivastava, Ashwini K. [Department of Chemistry, University of Mumbai, Vidyanagari, Santacruz (East), Mumbai 400098 (India)], E-mail: aksrivastava@chem.mu.ac.in

    2007-12-31

    Voltammetric behavior of folic acid at plain carbon paste electrode and electrode modified with calixarenes has been studied. Two peaks for irreversible oxidation were observed. Out of the three calixarenes chosen for modification of the electrodes, p-tert-butyl-calix[6]arene modified electrode (CME-6) was found to have better sensitivity for folic acid. Chronocoulometric and differential pulse voltammetric studies reveal that folic acid can assemble at CME-6 to form a monolayer whose electron transfer rate is 0.00273 s{sup -1} with 2-electron/2-proton transfer for the peak at +0.71 V against SCE. An adsorption equilibrium constant of 5 x 10{sup 3} l/mol for maximum surface coverage of 2.89 x 10{sup -10} mol/cm{sup 2} was obtained. The current is found to be rectilinear with concentration by differential pulse voltammetry. However, linearity in the lower range of concentration 8.79 x 10{sup -12} M to 1.93 x 10{sup -9} M with correlation coefficient of 0.9920 was achieved by adsorptive stripping voltammetry. The limit of detection obtained was found to be 1.24 x 10{sup -12} M. This method was used for the determination of folic acid in a variety of samples, viz. serum, asparagus, spinach, oranges and multivitamin preparations.

  19. Antitumor activity of chemical modified natural compounds

    Directory of Open Access Journals (Sweden)

    Marilda Meirelles de Oliveira

    1991-01-01

    Full Text Available Search of new activity substances starting from chemotherapeutic agents, continously appears in international literature. Perhaps this search has been done more frequently in the field of anti-tumor chemotherapy on account of the unsuccess in saving advanced stage patients. The new point in this matter during the last decade was computer aid in planning more rational drugs. In near future "the accessibility of supercomputers and emergence of computer net systems, willopen new avenues to rational drug design" (Portoghese, P. S. J. Med. Chem. 1989, 32, 1. Unknown pharmacological active compounds synthetized by plants can be found even without this eletronic devices, as tradicional medicine has pointed out in many contries, and give rise to a new drug. These compounds used as found in nature or after chemical modifications have produced successful experimental medicaments as FAA, "flavone acetic acid" with good results as inibitors of slow growing animal tumors currently in preclinical evaluation for human treatment. In this lecture some international contributions in the field of chemical modified compounds as antineoplasic drugs will be examined, particularly those done by Brazilian researches.

  20. Photocatalysis-triggered ion rectification in artificial nanochannels based on chemically modified asymmetric TiO2 nanotubes.

    Science.gov (United States)

    Hu, Ziying; Zhang, Qianqian; Gao, Jun; Liu, Zhaoyue; Zhai, Jin; Jiang, Lei

    2013-04-16

    Ion rectification is one of the important characteristics of biological ion channels. Inspired by the function of biological ion channels, creation of artificial nanochannels that show analogous ion rectification characteristics has attracted a great interest recently. Herein, we demonstrate a new type of artificial solid-state nanochannel with ion rectification characteristics. The creation of artificial nanochannels includes the formation of asymmetric TiO2 nanotubes by electrochemical anodization of Ti metal, followed by chemical modification with octadecyltrimethoxysilane (OTS) molecules. The carboxylic groups are introduced onto the tip side of TiO2 nanotubes via photocatalytic decomposition of OTS molecules by TiO2 photocatalysis under ultraviolet light. When the radius of tip side of TiO2 nanotubular channels is comparable to the thickness of electric double layer, the negatively charged surface in neutral electrolyte in combination with the asymmetric pore geometry contributes to the ion rectification characteristics. Compared with previous artificial nanochannels, our new type of artificial nanochannel is more facile to fabricate and behaves as a diode that rectifies the ion transport, which also shows some other potential applications, such as sensor and separation materials.

  1. Potassium selective chemically modified field effect transistors based on AlGaN/GaN two-dimensional electron gas heterostructures.

    Science.gov (United States)

    Alifragis, Y; Volosirakis, A; Chaniotakis, N A; Konstantinidis, G; Adikimenakis, A; Georgakilas, A

    2007-06-15

    We investigate the use of the AlGaN/GaN high electron mobility transistor (HEMT) as a novel transducer for the development of ion-selective chemically modified HEMT sensors (ChemHEMTs). For this, polyvinyl chloride (PVC) membrane doped with ion-selective ionophores is deposited onto the area of the gate for the chemical recognition step, while the AlGaN/GaN HEMT is used as the transducer. In particular, the use of a valinocycin doped membrane with thickness of 50 microm generates a sensor with excellent analytical characteristics for the monitoring of K(+). The K(+)-ChemHEMT has sensitivity of 52.4 mV/pK(+)in the linear range of 10(-5) to 10(-2)M, while the detection limit is in the order of 3.1 x 10(-6)M. Also, the sensor shows selectivity similar to valinomycin-based ISEs, while the signal stability over time and the measurement to measurement reproducibility are very good.

  2. Gene silencing by chemically modified siRNAs.

    Science.gov (United States)

    Engels, Joachim W

    2013-03-25

    RNA interference (RNAi) has not only already risen as a gold standard for validating gene function in basic science studies, but also holds great promise as a new therapeutic paradigm. Advantages of RNAi-based therapeutics include relatively fast initial screening and the ability to target proteins not yet addressable by traditional drug design strategies. In this review we describe the development of chemically modified small inhibiting siRNAs and their application as potential therapeutics during the past decade. Focus is on proper siRNA design, choice of chemical modification and how to circumvent immunogenicity as well as off-target effects.

  3. Lubricants from chemically modified vegetable oils.

    Science.gov (United States)

    Campanella, Alejandrina; Rustoy, Eduardo; Baldessari, Alicia; Baltanás, Miguel A

    2010-01-01

    This work reports laboratory results obtained from the production of polyols with branched ether and ester compounds from epoxidized vegetable oils pertaining to annual, temperate climate crops (soybean, sunflower and high-oleic sunflower oils), focusing on their possible use as components of lubricant base stocks. To this end, two different opening reactions of the epoxide ring were studied. The first caused by the attack with glacial acetic acid (exclusively in a single organic phase) and the second using short-chain aliphatic alcohols, methanol and ethanol, in acid media. Both reactions proceed under mild conditions: low synthesis temperature and short reaction times and with conversions above 99%. Spectroscopic (NMR), thermal (DSC) and rheological techniques were used to characterize the oils, their epoxides and polyols, to assess the impact of the nature of the vegetable oil and the chemical modifications introduced, including long-term storage conditions. Several correlations were employed to predict the viscosity of the vegetable oils with temperature, and good agreement with the experimental data was obtained.

  4. Probing Chromatin-modifying Enzymes with Chemical Tools

    KAUST Repository

    Fischle, Wolfgang

    2016-02-04

    Chromatin is the universal template of genetic information in all eukaryotic organisms. Chemical modifications of the DNA-packaging histone proteins and the DNA bases are crucial signaling events in directing the use and readout of eukaryotic genomes. The enzymes that install and remove these chromatin modifications as well as the proteins that bind these marks govern information that goes beyond the sequence of DNA. Therefore, these so-called epigenetic regulators are intensively studied and represent promising drug targets in modern medicine. We summarize and discuss recent advances in the field of chemical biology that have provided chromatin research with sophisticated tools for investigating the composition, activity, and target sites of chromatin modifying enzymes and reader proteins.

  5. Cyclic Voltammetric Responses of Nitrate Reductase on Chemical Modified Electrodes

    Institute of Scientific and Technical Information of China (English)

    YaRuSONG; HuiBoSHAO; 等

    2002-01-01

    Electrochemistry of nitrate reductases (NR) incorporated into 2-aminoethanethiol self-assembled on the gold electrode and polyacrylamide cast on the pyrolytic graphite electrode was examined. NR on chemical modified electrode showed electrochemical cyclic voltammetric responses in phosphate buffers.

  6. Chemically modified field effect transistors with nitrite or fluoride selectivity

    NARCIS (Netherlands)

    Antonisse, Martijn M.G.; Snellink-Ruël, Bianca H.M.; Engbersen, Johan F.J.; Reinhoudt, David N.

    1998-01-01

    Polysiloxanes with different types of polar substituents are excellent membrane materials for nitrite and fluoride selective chemically modified field effect transistors (CHEMFETs). Nitrite selectivity has been introduced by incorporation of a cobalt porphyrin into the membrane; fluoride selectivity

  7. Chemically modified field effect transistors with nitrite or fluoride selectivity

    NARCIS (Netherlands)

    Antonisse, M.M.G.; Ruel, Bianca H.M.; Engbersen, Johannes F.J.; Reinhoudt, David

    1998-01-01

    Polysiloxanes with different types of polar substituents are excellent membrane materials for nitrite and fluoride selective chemically modified field effect transistors (CHEMFETs). Nitrite selectivity has been introduced by incorporation of a cobalt porphyrin into the membrane; fluoride selectivity

  8. Chemical and semisynthesis of modified histones.

    Science.gov (United States)

    Maity, Suman Kumar; Jbara, Muhammad; Brik, Ashraf

    2016-05-01

    Post-translational modifications (PTMs) of histones play critical roles in the epigenetic regulation of eukaryotic genome by directly altering the biophysical properties of chromatin or by recruiting effector proteins. The large number of PTMs and the inherent complexity in their population and signaling processes make it highly challenging to understand epigenetics-related processes. To address these challenges, accesses to homogeneously modified histones are obligatory. Over the last decade, synthetic protein chemists have been devising novel synthetic tools and applying state-of-the-art chemoselective ligation strategies to prepare precious materials useful in answering fundamental questions in this area. In this short review, we cover some of the recent breakthroughs in these directions in particular the synthesis and semi-synthesis of modified histones and their use to unravel the mysteries of epigenetics. Copyright © 2016 European Peptide Society and John Wiley & Sons, Ltd.

  9. Chemically modified solid state nanopores for high throughput nanoparticle separation

    Energy Technology Data Exchange (ETDEWEB)

    Prabhu, Anmiv S; Kim, Min Jun [School of Biomedical Engineering and Health Science, Drexel University, Philadelphia, PA 19104 (United States); Jubery, Talukder Zaki N; Dutta, Prashanta [School of Mechanical and Materials Engineering, Washington State University, Pullman, WA 99164 (United States); Freedman, Kevin J; Mulero, Rafael, E-mail: mkim@coe.drexel.ed [Department of Mechanical Engineering and Mechanics, Drexel University, Philadelphia, PA 19104 (United States)

    2010-11-17

    The separation of biomolecules and other nanoparticles is a vital step in several analytical and diagnostic techniques. Towards this end we present a solid state nanopore-based set-up as an efficient separation platform. The translocation of charged particles through a nanopore was first modeled mathematically using the multi-ion model and the surface charge density of the nanopore membrane was identified as a critical parameter that determines the selectivity of the membrane and the throughput of the separation process. Drawing from these simulations a single 150 nm pore was fabricated in a 50 nm thick free-standing silicon nitride membrane by focused-ion-beam milling and was chemically modified with (3-aminopropyl)triethoxysilane to change its surface charge density. This chemically modified membrane was then used to separate 22 and 58 nm polystyrene nanoparticles in solution. Once optimized, this approach can readily be scaled up to nanopore arrays which would function as a key component of next-generation nanosieving systems.

  10. CONCRETE BASED ON MODIFIED DISPERSE CEMENT SYSTEM

    Directory of Open Access Journals (Sweden)

    D. V. Rudenko

    2016-08-01

    and chemical processes of hydration of clinker minerals allowed developing technological bases for special-purpose concrete.

  11. [Adsorption of phenol chemicals by surfactant-modified zeolites].

    Science.gov (United States)

    Xie, Jie; Wang, Zhe; Wu, De-Yi; Li, Chun-Jie

    2012-12-01

    Two kinds of zeolites were prepared from fly ash and modified by surfactant subsequently. Surfactant-modified zeolites were studied for adsorption of phenol chemicals (phenol, p-chlorphenol, bisphenol A). It showed that the adsorption affinity of zeolite to phenol chemicals was significantly improved after surfactant modification. The adsorption isotherms of phenol chemicals were well fitted by the Langmuir isotherm. For the two surfactant-surfactant modified zeolites, the maximum adsorption amounts of phenol, p-chlorphenol, and bisphenol A calculated from the Langmuir equation were 37.7, 52.36, 90.9 mg x g(-1) and 10.7, 22.83, 56.8 mg x g(-1), respectively. When pH values of solutions were higher than the pK(a) values of phenol chemicals, the removal efficiencies were getting higher with the increase of pH values. The octanol/water partition coefficient (K(ow)) was also found to be an important factor affecting adsorption of phenol chemicals by the modified zeolites. Higher K(ow) value, which means the greater hydrophobicity of the chemicals, resulted in a higher removal.

  12. Structure and biological activity of chemically modified nisin A species

    NARCIS (Netherlands)

    Rollema, Harry S.; Metzger, Jörg W.; Both, Paula; Kuipers, Oscar P.; Siezen, Roland J.

    1996-01-01

    Nisin, a 34-residue peptide bacteriocin, contains the less common amino acids lanthionine, β-methyllanthionine, dehydroalanine (Dha), and dehydrobutyrine (Dhb). Several chemically modified nisin A species were purified by reverse-phase HPLC and characterized by two-dimensional NMR and electrospray m

  13. Modified NASA-Lewis Chemical Equilibrium Code for MHD applications

    Energy Technology Data Exchange (ETDEWEB)

    Sacks, R. A.; Geyer, H. K.; Grammel, S. J.; Doss, E. D.

    1979-12-01

    A substantially modified version of the NASA-Lewis Chemical Equilibrium Code has recently been developed. The modifications were designed to extend the power and convenience of the Code as a tool for performing combustor analysis for MHD systems studies. This report describes the effect of the programming details from a user point of view, but does not describe the Code in detail.

  14. Structure and biological activity of chemically modified nisin A species

    NARCIS (Netherlands)

    Rollema, Harry S.; Metzger, Jörg W.; Both, Paula; Kuipers, Oscar P.; Siezen, Roland J.

    1996-01-01

    Nisin, a 34-residue peptide bacteriocin, contains the less common amino acids lanthionine, β-methyllanthionine, dehydroalanine (Dha), and dehydrobutyrine (Dhb). Several chemically modified nisin A species were purified by reverse-phase HPLC and characterized by two-dimensional NMR and electrospray m

  15. Extraction of metal ions using chemically modified silica gel covalently bonded with 4,4'-diaminodiphenylether and 4,4'-diaminodiphenylsulfone-salicylaldehyde Schiff bases.

    Science.gov (United States)

    Dey, R K; Jha, Usha; Singh, A C; Samal, S; Ray, Alok R

    2006-08-01

    Two new chelating materials (Si-DDE-o-HB, and Si-DDS-o-HB) were synthesized by modifying the activated silica gel phase with Schiff bases of 4,4'-diaminodiphenylether (DDE)/4,4'-diaminodiphenylsulfone (DDS) and o-hydroxybenzaldehyde (o-HB). The synthesized materials were characterized by FTIR and BET surface area measurement techniques. The extraction of metal ions such as Zn2+, Mn2+ and Cr3+ by the chelating material Si-DDE-o-HB was found to be higher than that by Si-DDS-o-HB. The order of metal sorption was found to be Zn2+ > Mn2+ > Cr3+. The correlation coefficients for Freundlich and Langmuir adsorption isotherms were compared for the sorption of Zn2+ onto the chelating material. The loading and elution of the metal ion solution was examined at optimum pH 7.5 and 0.5 cm3 min-1 flow rate of the solution using a column technique. The preconcentration factor for the elution of Zn2+ using dilute HNO3 was found to be 66.2 with a breakthrough volume of 15 cm3. The data obtained for the preconcentration of Zn2+ by the column technique suggested that the material Si-DDE-o-HB can find industrial applications.

  16. THE INDUSTRIAL UTILIZATION OF CHEMICAL MODIFIED AGRICULTURAL RESIDUES

    Institute of Scientific and Technical Information of China (English)

    Feng Xu; Runcang Sun; Huaiyu Zhan

    2004-01-01

    Various lignocellulosic materials such as wood,agricultural and forest residues has the potential to be valuable substitute for, or complement to,commercial sorbents for removing heavy metal ions or dyes from waste water or spilled oil from inland water or sea. More than 9 million tons of straw pulp are produced annually in china, which account for about 90% of the world′s total straw pulp. However,huge quantity of remain straw is not used as industrial raw material and is burnt in the fields or on the side of road. These resources can be chemical modified such as acetylation. Modified straws have the characteristics of low cost, high capacity, quick uptake, and easy to desorb. This paper reviews the current status of the technology for modified agricultural residues, which focus on hemicellulose and cellulose. The potential of these natural sorbents in main industry is also indicated.

  17. THE INDUSTRIAL UTILIZATION OF CHEMICAL MODIFIED AGRICULTURAL RESIDUES

    Institute of Scientific and Technical Information of China (English)

    FengXu; RuncangSun; HuaiyuZhan

    2004-01-01

    Various lignocellulosic materials such as wood, agricultural and forest residues has the potential to be valuable substitute for, or complement to, commercial sorbents for removing heavy metal ions or dyes from waste water or spilled oil from inland water or sea. More than 9 million tons of straw pulp are produced annually in china, which account for about 90% of the world's total straw pulp. However, huge quantity of remain straw is not used as industrial raw material and is burnt in the fields or on the side of road. These resources can be chemical modified such as acetylation. Modified straws have the characteristics of low cost, high capacity, quick uptake, and easy to desorb. This paper reviews the current status of the technology for modified agricultural residues, which focus on hemicellulose and cellulose. The potential of these natural sorbents in main industry is also indicated.

  18. Chemical characteristics and volatile profile of genetically modified peanut cultivars.

    Science.gov (United States)

    Ng, Ee Chin; Dunford, Nurhan T; Chenault, Kelly

    2008-10-01

    Genetic engineering has been used to modify peanut cultivars for improving agronomic performance and pest resistance. Food products developed through genetic engineering have to be assessed for their safety before approval for human consumption. Preservation of desirable chemical, flavor and aroma attributes of the peanut cultivars during the genetic modifications is critical for acceptance of genetically modified peanuts (GMP) by the food industry. Hence, the main objective of this study is to examine chemical characteristics and volatile profile of GMP. The genetically modified peanut cultivars, 188, 540 and 654 were obtained from the USDA-ARS in Stillwater, Oklahoma. The peanut variety Okrun was examined as a control. The volatile analysis was performed using a gas chromatograph/mass spectrometer (GC/MS) equipped with an olfactory detector. The peanut samples were also analyzed for their moisture, ash, protein, sugar and oil compositions. Experimental results showed that the variations in nutritional composition of peanut lines examined in this study were within the values reported for existing cultivars. There were minor differences in volatile profile among the samples. The implication of this study is significant, since it shows that peanut cultivars with greater pest and fungal resistance were successfully developed without major changes in their chemical characteristics.

  19. Chemically modified cellulose paper as a thin film microextraction phase.

    Science.gov (United States)

    Saraji, Mohammad; Farajmand, Bahman

    2013-11-01

    In this paper, chemically modified cellulose paper was introduced as a novel extracting phase for thin film microextraction (TFME). Different reagents (Octadecyltrichlorosilane, diphenyldichlorosilane, cyclohexyl isocyanate and phenyl isocyanate) were used to modify the cellulose papers. The modified papers were evaluated as a sorbent for the extraction of some synthetic and natural estrogenic hormones (17α-ethynylestradiol, estriol and estradiol) from aqueous samples. Liquid chromatography-fluorescence detection was used for the quantification of the extracted compounds. The cellulose paper modified with phenyl isocyanate showed the best affinity to the target compounds. TEME parameters such as desorption condition, shaking rate, sample ionic strength and extraction time were investigated and optimized. Limit of detections were between 0.05 and 0.23μgL(-1) and relative standard deviations were less than 11.1% under the optimized condition. The calibration curves were obtained in the range of 0.2-100μgL(-1) with a good linearity (r(2)>0.9935). Wastewater, human urine, pool and river water samples were studied as real samples for the evaluation of the method. Relative recoveries were found to be between 75% and 101%.

  20. Recovery of palladium using chemically modified cedar wood powder.

    Science.gov (United States)

    Parajuli, Durga; Hirota, Koichi

    2009-10-15

    Japanese cedar wood powder (CWP) was chemically modified to a tertiary-amine-type adsorbent and studied for the selective recovery of Pd(II) from various industrial waters. Batch adsorption tests performed from 0.1 M to 5 M HCl and HNO3 systems reveal stable performance with better results in HNO3 medium. The maximum loading capacity for Pd(II) was studied in HCl as well as in HNO3. A continuous-flow experiment taking a real industrial solution revealed the feasibility of using modified CWP for the selective uptake and preconcentration of traces of palladium contained in acidic effluents. In addition, stable adsorption performance even on long exposure to gamma-irradiation and selective recovery of palladium from simulated high-level liquid waste (HLW) are important outcomes of the study.

  1. Chemically modified oligonucleotides with efficient RNase H response

    DEFF Research Database (Denmark)

    Vester, Birte; Boel, Anne Marie; Lobedanz, Sune;

    2008-01-01

    Ten different chemically modified nucleosides were incorporated into short DNA strands (chimeric oligonucleotides ON3-ON12 and ON15-ON24) and then tested for their capacity to mediate RNAse H cleavage of the complementary RNA strand. The modifications were placed at two central positions directly...... in the RNase H cleaving region. The RNA strand of duplexes with ON3, ON5 and ON12 were cleaved more efficiently than the RNA strand of the DNA:RNA control duplex. There seems to be no correlation between the thermal stability between the duplexes and RNase H cleavage....

  2. Chemically modified tetracyclines: The novel host modulating agents

    Directory of Open Access Journals (Sweden)

    Devulapalli Narasimha Swamy

    2015-01-01

    Full Text Available Periodontal pathogens and destructive host responses are involved in the initiation and progression of periodontitis. The emergence of host response modulation as a treatment concept has resulted from our improved understanding of the pathogenesis of periodontal disease. A variety of drugs have been evaluated as host modulation agents (HMA, including Non Steroidal Anti Inflammatory Drugs (NSAIDS, bisphosphonates, tetracyclines, enamel matrix proteins and bone morphogenetic proteins. Chemically modified tetracyclines (CMTs are one such group of drugs which have been viewed as potential host modulating agents by their anticollagenolytic property. The CMTs are designed to be more potent inhibitors of pro inflammatory mediators and can increase the levels of anti inflammatory mediators.

  3. Mechano-sorptive creep of Portuguese pinewood chemically modified

    Directory of Open Access Journals (Sweden)

    Barroso Lopes Duarte

    2014-03-01

    Full Text Available The effect of chemical modification on mechano-sorptive creep in bending was studied by experimental work. Stakes with 20 × 20 × 400 mm RTL of Portuguese wood species (Pinus pinaster Aiton modified with 1,3-dimethylol-4,5- dihydroxyethyleneurea (DMDHEU, m-methylated melamine resin (MMF, tetraethoxysilane (TEOS and amid wax (WA were measured under asymmetric moistening conditions over a period of 42 days (app. 1000 hours with stress level (SL of 12 MPa, according to ENV 1156.

  4. Reduced chemically modified graphene oxide for supercapacitor electrode.

    Science.gov (United States)

    Rajagopalan, Balasubramaniyan; Chung, Jin Suk

    2014-01-01

    An efficient active material for supercapacitor electrodes is prepared by reacting potassium hydroxide (KOH) with graphene oxide followed by chemical reduction with hydrazine. The electrochemical performance of KOH treated graphene oxide reduced for 24 h (reduced chemically modified graphene oxide, RCMGO-24) exhibits a specific capacitance of 253 F g(-1) at 0.2 A g(-1) in 2 M H2SO4 compared to a value of 141 F g(-1) for graphene oxide reduced for 24 h (RGO-24), and good cyclic stability up to 3,000 cycles. Interestingly, RCMGO-24 demonstrated a higher specific capacitance and excellent cycle stability due to its residual oxygen functional groups that accelerate the faradaic reactions and aid in faster wetting. This non-annealed strategy offers the potential for simple and cost-effective preparation of an active material for a supercapacitor electrode.

  5. Band bending and electrical transport at chemically modified silicon surfaces

    Science.gov (United States)

    Lopinski, Greg; Ward, Tim; Hul'Ko, Oleksa; Boukherroub, Rabah

    2002-03-01

    High resolution electron energy loss spectroscopy (HREELS) and electrical transport measurements have been used to investigate how various chemical modifications give rise to band bending and alter the conductivity of Si(111) surfaces. HREELS is a sensitive probe of band bending through observations of the low frequency free carrier plasmon mode. For hydrogen terminated surfaces, prepared by the standard etch in ammonium flouride, HREELS measurements on both n and n+ substrates are consistent with nearly flat bands. Chlorination of these surfaces results in substantial upward band bending due to the strong electron withdrawing nature of the chlorine, driving the surface into inversion. The presence of this inversion layer on high resistivity n-type samples is observed through a substantial enhancement of the surface conductivity (relative to the H-terminated surface), as well as through broadening of the quasi-elastic peak in the HREELS measurements. We have also begun to examine organically modified silicon surfaces, prepared by various wet chemical reactions with the H-terminated surface. Decyl modified Si(111) surfaces are seen to exhibit a small degree of band bending, attributed to extrinsic defect states cause by a small degree of oxidation accompanying the modification reaction. The prospects of using conductivity as an in-situ monitor of the rate of these reactions will be discussed.

  6. Nanoparticles Modified ITO Based Biosensor

    Science.gov (United States)

    Khan, M. Z. H.

    2017-04-01

    Incorporation of nanomaterials with controlled molecular architecture shows great promise in improving electronic communication between biomolecules and the electrode substrate. In electrochemical applications metal nanoparticles (NPs) modified electrodes have been widely used and are emerging as candidates to develop highly sensitive electrochemical sensors. There has been a growing technological interest in modified indium tin oxide (ITO) electrodes due to their prominent optoelectronic properties and their wide use as a transducing platform. The introduction of NPs into the transducing platform is commonly achieved by their adsorption onto conventional electrode surfaces in various forms, including that of a composite. The aim of this review is to discuss the role of metallic NPs for surface fabrication of ITO thin films leading to detection of specific biomolecules and applications as a biosensor platform.

  7. Nanoparticles Modified ITO Based Biosensor

    Science.gov (United States)

    Khan, M. Z. H.

    2016-12-01

    Incorporation of nanomaterials with controlled molecular architecture shows great promise in improving electronic communication between biomolecules and the electrode substrate. In electrochemical applications metal nanoparticles (NPs) modified electrodes have been widely used and are emerging as candidates to develop highly sensitive electrochemical sensors. There has been a growing technological interest in modified indium tin oxide (ITO) electrodes due to their prominent optoelectronic properties and their wide use as a transducing platform. The introduction of NPs into the transducing platform is commonly achieved by their adsorption onto conventional electrode surfaces in various forms, including that of a composite. The aim of this review is to discuss the role of metallic NPs for surface fabrication of ITO thin films leading to detection of specific biomolecules and applications as a biosensor platform.

  8. Chemically modified bitumens with enhanced rheology and adhesion properties to siliceous aggregates

    OpenAIRE

    Cuadri Vega, Antonio Abad; Partal López, Pedro; Ahmad, Naveed; Grenfell, James; Airey, Gordon

    2015-01-01

    Moisture damage is one of the major premature failures that worsens the performance and shortens service life of pavements. This research assesses the effect that two chemical modifiers (thiourea and an isocyanate-functionalized castor oil prepolymer) exerts on the bitumen rheology and on the resistance to potential moisture damage of asphalt mixtures based on siliceous aggregates. Both thiourea and the isocyanate-based prepolymer improve the viscous and viscoelastic behaviours of bitumen at ...

  9. Chemically modified bitumens with enhanced rheology and adhesion properties to siliceous aggregates

    OpenAIRE

    Cuadri Vega, Antonio Abad; Partal López, Pedro; Ahmad, Naveed; Grenfell, James; Airey, Gordon

    2015-01-01

    Moisture damage is one of the major premature failures that worsens the performance and shortens service life of pavements. This research assesses the effect that two chemical modifiers (thiourea and an isocyanate-functionalized castor oil prepolymer) exerts on the bitumen rheology and on the resistance to potential moisture damage of asphalt mixtures based on siliceous aggregates. Both thiourea and the isocyanate-based prepolymer improve the viscous and viscoelastic behaviours of bitumen at ...

  10. 基于石墨烯化学修饰电极的适体传感器%Aptasensor Based on Graphene Chemically Modified Electrode

    Institute of Scientific and Technical Information of China (English)

    王延平; 肖迎红; 吴敏; 陆天虹; 杨小弟

    2012-01-01

    采用石墨烯(RGO)作载体,凝血酶适体(TBA)作探针,凝血酶为目标蛋白,电化学阻抗谱(EIS)为检测技术,建立了检测蛋白质的新方法.由于RGO可增大电极有效表面积并提高电极表面电子传输速率以及TBA的特异性识别能力,此方法具有较高的灵敏度和良好的选择性.采用本方法检测凝血酶的线性范围为0.3~10 fmol/L,检出限为0.26 fmol/L.本研究将RGO应用于电化学适体传感器,证实了RGO修饰电极在电化学适体传感器领域中潜在的应用价值.%By using graphene (RGO) as supporter, molecular recognition substance TBA as probe, thrombin as objective protein, electrochemical impedance spectroscopy ( EIS) as determination technique, a method for the determination of proteins was developed. Because RGO can improve effective surface area of electrodes and accelerate electron transfer rate at electrode/electrolyte interface as well as TBA has the molecular recognition ability with the high specificity, this determination method possesses the high sensitivity and good specificity. In the linear range from 0. 3 to 10 fmol/L for thrombin determination, the detection limit is 0. 26 fmol/L. In this study, RGO was applied to the electrochemical aptasensor for the first time, demonstrating that RGO-modified electrode has the great potential for the application in the electrochemical aptasensor.

  11. Preparation of calcium stannate by modified wet chemical method

    Institute of Scientific and Technical Information of China (English)

    何则强; 李新海; 刘恩辉; 侯朝辉; 邓凌峰; 胡传跃

    2003-01-01

    A modified wet chemical route for low-temperature synthesis of the calcium stannate CaSnO3, a potentialmaterial for dielectric applications is reported. Firstly, a precursor CaSn(OH)6 was prepared using tin tetrachloride,calcium chloride and sodium hydroxide at room temperature. Then the precursor was annealed at relatively low tem-perature of 600 ℃ to obtain CaSnO3. The phase identification, thermal behavior and surface morphology of the sam-ples were characterized by element analysis, X-ray diffraction (XRD), thermo-gravimetric (TG) analysis and deriva-tive thermo-gravimetric (DTG) analysis, Fourier transform infrared spectroscopy (FTIR) and scanning electron mi-croscopy (SEM) in detail. The results show that CaSnO3 obtained by this method possesses a cubic perovskitestructure with average grain size of 5 μm.

  12. 12-Tungstophosphates Immobilized on Chemically Modified Mesoporous Silica SBA-15

    Institute of Scientific and Technical Information of China (English)

    ZHU Jing; YOU Wan-sheng; ZHU Zai-ming; SUN Zhen-gang; ZHANG Lan-cui; GU Yuan-peng

    2005-01-01

    A functionalized material, PW/SBA-15m, was prepared successfully in diluted H2SO4 aqueous solutions by immobilizing 12-tungstophosphates on chemically modified mesoporous silica SBA-15 and characterized by elemental analysis, FTIR, 31P MAS NMR, XRD and TEM. The results indicate that the framework of SBA-15 and the Keggin structure of PW12O3-40 were retained, and that 23%-33%(mass fraction) of PW12O3-40 was immobilized; the PW12O3-40 anions were finely dispersed on the pore wall of SBA-15. Having been leached in ethanol at 60 ℃ for 7 h, the loss of PW12O3-40 anions was not found.

  13. Highly efficient adsorption of chlorophenols onto chemically modified chitosan

    Science.gov (United States)

    Zhou, Liang-Chun; Meng, Xiang-Guang; Fu, Jing-Wei; Yang, Yu-Chong; Yang, Peng; Mi, Chun

    2014-02-01

    A novel chemically modified chitosan CS-SA-CD with phenol and β-cyclodextrin groups was prepared. The adsorptions of phenol, 2-chlorophenol (2-CP), 4-chlorophenol (4-CP), 2,4-dichlorophenol (DCP) and 2,4,6-trichlorophenol (TCP) on the functional chitosan from aqueous solution were investigated. CS-SA-CD exhibited excellent adsorption ability for chlorophenols especially for DCP and TCP. The maximum adsorption capacities of phenol, 2-CP, 4-CP, DCP and TCP on CS-SA-CD were 59.74, 70.52, 96.43, 315.46 and 375.94 mg/g, respectively. The scanning electron microscope and Brunauer-Emmett-Teller analyses revealed that the introduction of phenol group changed the surface morphology and surface properties of chitosan. The modified chitosan CS-SA-CD possesses larger surface areas (4.72 m2/g), pore volume (7.29 × 10-3 mL/g) and average pore diameter (59.99 Å) as compared to those of chitosan 3.27 m2/g, 2.00 × 10-3 mL/g and 15.95 Å, respectively. The enhanced adsorption of chlorophenols was also attributed to the interaction of hydrogen bond between Cl atom and sbnd OH group. The adsorption of chlorophenols on CS-SA-CD followed the pseudo-second-order kinetic model. Adsorbent could be regenerated easily and the regenerated CS-SA-CD remained 80-91% adsorption efficiency.

  14. Fabrication of Rare Earth-Doped Transparent Glass Ceramic Optical Fibers by Modified Chemical Vapor Deposition

    OpenAIRE

    2011-01-01

    International audience; Rare earth (RE) doped silica-based optical fibers with transparent glass ceramic (TGC) core was fabricated through the well-known modified chemical vapor deposition (MCVD) process without going through the commonly used stage of post-ceramming. The main characteristics of the RE-doped oxyde nanoparticles namely, their density and mean diameter in the fibers are dictated by the concentration of alkaline earth element used as phase separating agent. Magnesium and erbium ...

  15. Highly efficient adsorption of chlorophenols onto chemically modified chitosan

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Liang-Chun [Key Laboratory of Green Chemistry and Technology, Ministry of Education, College of Chemistry, Sichuan University, Chengdu 610064 (China); National Center for Packaging Material Quality Supervision and Inspection, Chengdu Institute of Product Quality Supervision and Inspection, Chengdu 610064 (China); Meng, Xiang-Guang, E-mail: mengxgchem@163.com [Key Laboratory of Green Chemistry and Technology, Ministry of Education, College of Chemistry, Sichuan University, Chengdu 610064 (China); Fu, Jing-Wei [National Center for Packaging Material Quality Supervision and Inspection, Chengdu Institute of Product Quality Supervision and Inspection, Chengdu 610064 (China); Yang, Yu-Chong; Yang, Peng; Mi, Chun [Key Laboratory of Green Chemistry and Technology, Ministry of Education, College of Chemistry, Sichuan University, Chengdu 610064 (China)

    2014-02-15

    A novel chemically modified chitosan CS-SA-CD with phenol and β-cyclodextrin groups was prepared. The adsorptions of phenol, 2-chlorophenol (2-CP), 4-chlorophenol (4-CP), 2,4-dichlorophenol (DCP) and 2,4,6-trichlorophenol (TCP) on the functional chitosan from aqueous solution were investigated. CS-SA-CD exhibited excellent adsorption ability for chlorophenols especially for DCP and TCP. The maximum adsorption capacities of phenol, 2-CP, 4-CP, DCP and TCP on CS-SA-CD were 59.74, 70.52, 96.43, 315.46 and 375.94 mg/g, respectively. The scanning electron microscope and Brunauer–Emmett–Teller analyses revealed that the introduction of phenol group changed the surface morphology and surface properties of chitosan. The modified chitosan CS-SA-CD possesses larger surface areas (4.72 m{sup 2}/g), pore volume (7.29 × 10{sup −3} mL/g) and average pore diameter (59.99 Å) as compared to those of chitosan 3.27 m{sup 2}/g, 2.00 × 10{sup −3} mL/g and 15.95 Å, respectively. The enhanced adsorption of chlorophenols was also attributed to the interaction of hydrogen bond between Cl atom and -OH group. The adsorption of chlorophenols on CS-SA-CD followed the pseudo-second-order kinetic model. Adsorbent could be regenerated easily and the regenerated CS-SA-CD remained 80–91% adsorption efficiency.

  16. The 5' binding MID domain of human Argonaute2 tolerates chemically modified nucleotide analogues.

    Science.gov (United States)

    Deleavey, Glen F; Frank, Filipp; Hassler, Matthew; Wisnovsky, Simon; Nagar, Bhushan; Damha, Masad J

    2013-02-01

    Small interfering RNAs (siRNAs) can trigger potent gene silencing through the RNA interference (RNAi) pathway. The RNA-induced silencing complex (RISC) is key to this targeted mRNA degradation, and the human Argonaute2 (hAGO2) endonuclease component of RISC is responsible for the actual mRNA cleavage event. During RNAi, hAGO2 becomes loaded with the siRNA guide strand, making several key nucleic acid-enzyme interactions. Chemically modified siRNAs are now widely used in place of natural double-stranded RNAs, and understanding the effects chemical modifications have on guide strand-hAGO2 interactions has become particularly important. Here, interactions between the 5' nucleotide binding domain of hAGO2, MID, and chemically modified nucleotide analogues are investigated. Measured dissociation constants reveal that hAGO2 does not discriminate between nucleotide analogues during binding, regardless of the preferred sugar conformation of the nucleotide analogues. These results correlate well with cell-based gene silencing results employing siRNAs with 5'-modified guide strands. Additionally, chemical modification with 2'-deoxy-2'-fluoroarabino nucleic acid (2'F-ANA) and 2'-deoxy-2'-fluororibonucleic acid (2'F-RNA) at the passenger strand cleavage site of siRNAs has been shown to prevent hAGO2-mediated strand cleavage, an observation that appears to have little impact on overall gene silencing potency.

  17. Eigenvalue Decomposition-Based Modified Newton Algorithm

    Directory of Open Access Journals (Sweden)

    Wen-jun Wang

    2013-01-01

    Full Text Available When the Hessian matrix is not positive, the Newton direction may not be the descending direction. A new method named eigenvalue decomposition-based modified Newton algorithm is presented, which first takes the eigenvalue decomposition of the Hessian matrix, then replaces the negative eigenvalues with their absolute values, and finally reconstructs the Hessian matrix and modifies the searching direction. The new searching direction is always the descending direction. The convergence of the algorithm is proven and the conclusion on convergence rate is presented qualitatively. Finally, a numerical experiment is given for comparing the convergence domains of the modified algorithm and the classical algorithm.

  18. Chemically modified STM tips for atomic-resolution imaging of ultrathin NaCI films

    Institute of Scientific and Technical Information of China (English)

    Zhe Li[1; Koen Schouteden[1; Violeta lancu[1; Ewald Janssens[1; Peter Lievens[1; Chris Van Haesendonck[1; Jorge I. Cerda[2

    2015-01-01

    Cl-functionalized scanning tunneling microscopy (STM) tips are fabricated by modifying a tungsten STM tip in situ on islands of ultrathin NaCI(100) films on Au(111) surfaces. The functionalized tips are used to achieve clear atomic- resolution imaging of NaCI(100) islands. In comparison with bare metal tips, the chemically modified tips yield drastically enhanced spatial resolution as well as contrast reversal in STM topographs, implying that Na atoms, rather than C1 atoms, are imaged as protrusions. STM simulations based on a Green's function formalism reveal that the experimentally observed contrast reversal in the STM topographs is due to the highly localized character of the Cl-pz states at the tip apex. An additional remarkable characteristic of the modified tips is that in dI/dV maps, a Na atom appears as a ring with a diameter that depends crucially on the tip-sample distance.

  19. N-Modified Carbon-Based Materials: Nanoscience for Catalysis.

    Science.gov (United States)

    Prati, Laura; Chan-Thaw, Carine E; Campisi, Sebastiano; Villa, Alberto

    2016-10-01

    Carbon-based materials constitute a large family of materials characterized by some peculiarities such as resistance to both acidic and basic environments, flexibility of structure, and surface chemical groups. Moreover, they can be deeply modified by simple organic reactions (acid-base or redox) to acquire different properties. In particular, the introduction of N-containing groups, achieved by post-treatments or during preparation of the material, enhances the basic properties. Moreover, it has been revealed that the position and chemical nature of the N-containing groups is important in determining the interaction with metal nanoparticles, and thus, their reactivity. The modified activity was addressed to a different metal dispersion. Moreover, experiments on catalysts, showing the same metal dispersion, demonstrated that the best results were obtained when N was embedded into the carbon structure and not very close to the metal active site.

  20. Interfacial characterization and analytical applications of chemically-modified surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Jianhong [Iowa State Univ., Ames, IA (United States)

    1998-02-23

    The goal of this work is to explore several new strategies and approaches to the surface modification and the microscopic characterization of interfaces in the areas mainly targeting sensor technologies that are of interest to environmental control or monitoring, and scanning probe microscopies techniques that can monitor interfacial chemical reactions in real time. Centered on the main theme, four specific topics are presented as four chapters in this dissertation following the general introduction. Chapter 1 describes the development of two immobilization schemes for covalently immobilizing fluoresceinamine at cellulose acetate and its application as a pH sensing film. Chapter 2 investigates the applicability of SFM to following the base-hydrolysis of a dithio-bis(succinimidylundecanoate) monolayer at gold in situ. Chapter 3 studies the mechanism for the accelerated rate of hydrolysis of the dithio-bis(succinimidylundecanoate) monolayer at Au(111) surface. Chapter 4 focuses on the development of an electrochemical approach to the elimination of chloride interference in Chemical Oxygen Demand (COD) analysis of waste water. The procedures, results and conclusions are described in each chapter. This report contains the introduction, references, and general conclusions. Chapters have been processed separately for inclusion on the data base. 95 refs.

  1. Sensory and rheological properties of transgenically and chemically modified starch ingredients as evaluated in a food product model

    DEFF Research Database (Denmark)

    Ahmt, T.; Wischmann, Bente; Blennow, A.

    2004-01-01

    Starches derived from five genetically modified potato lines, two chemically modified potato starches and two native starches from potato and maize were subjected to physical and chemical analyses and their functionality evaluated in a milk-based food product model. The transgenic starches were...... gels with a higher tendency to retrograde and a low freeze/thaw stability as compared to starches with shorter amylopectin chains and lower phosphorous content. The textural properties of the food product model prepared from genetically and chemically modified starches were characterised by sensory...... and rheological analyses. To clearly visualise the effects of the modifications, data was evaluated by radar plots and multiple regression analysis (chemometrics). Genetically modified potato starches with longer amylopectin chains and increased phosphorous content gave a more gelled and a shorter texture...

  2. Photo- and electro-chromism of diarylethene modified ITO electrodes - towards molecular based read-write-erase information storage

    NARCIS (Netherlands)

    Areephong, J.; Browne, W.R.; Katsonis, N.; Feringa, B.L.

    2006-01-01

    Molecular memory devices based on dithienylethene switch modified ITO electrodes undergo reversible ring opening/closing both photo- and electro-chemically with non-destructive electrochemical readout.

  3. Highly dispersed Pd nanoparticles on chemically modified graphene with aminophenyl groups for formic acid oxidation

    Science.gov (United States)

    Yang, Su-Dong; Shen, Cheng-Min; Tong, Hao; He, Wei; Zhang, Xiao-Gang; Gao, Hong-Jun

    2011-11-01

    A novel electrode material based on chemically modified graphene (CMG) with aminophenyl groups is covalently functionalized by a nucleophilic ring-opening reaction between the epoxy groups of graphene oxide and the aminophenyl groups of p-phenylenediamine. Palladium nanoparticles with an average diameter of 4.2 nm are deposited on the CMG by a liquid-phase borohydride reduction. The electrocatalytic activity and stability of the Pd/CMG composite towards formic acid oxidation are found to be higher than those of reduced graphene oxide and commercial carbon materials such as Vulcan XC-72 supported Pd electrocatalysts.

  4. Deposition of carbon nanotubes onto aramid fibers using as-received and chemically modified fibers

    Energy Technology Data Exchange (ETDEWEB)

    Rodríguez-Uicab, O. [Centro de Investigación Científica de Yucatán A.C., Unidad de Materiales, Calle 43 No.130, Col. Chuburna de Hidalgo, C.P. 97200 Mérida, Yucatán (Mexico); Avilés, F., E-mail: faviles@cicy.mx [Centro de Investigación Científica de Yucatán A.C., Unidad de Materiales, Calle 43 No.130, Col. Chuburna de Hidalgo, C.P. 97200 Mérida, Yucatán (Mexico); Gonzalez-Chi, P.I; Canché-Escamilla, G.; Duarte-Aranda, S. [Centro de Investigación Científica de Yucatán A.C., Unidad de Materiales, Calle 43 No.130, Col. Chuburna de Hidalgo, C.P. 97200 Mérida, Yucatán (Mexico); Yazdani-Pedram, M. [Facultad de Ciencias Químicas y Farmacéuticas, Universidad de Chile, S. Livingstone 1007, Independencia, Santiago (Chile); Toro, P. [Facultad de Ciencias Físicas y Matemáticas, Universidad de Chile, Av. Beauchef 850, Santiago (Chile); Gamboa, F. [Centro de Investigacion y de Estudios Avanzados del IPN, Unidad Mérida, Depto. de Física Aplicada, Km. 6 Antigua Carretera a Progreso, 97310 Mérida, Yucatán (Mexico); Mazo, M.A.; Nistal, A.; Rubio, J. [Instituto de Cerámica y Vidrio (ICV-CSIC), Kelsen 5, 28049 Madrid (Spain)

    2016-11-01

    Highlights: • The surface of aramid fibers was functionalized by two acid treatments. • The treatment based on HNO{sub 3}/H{sub 2}SO{sub 4} reduced the mechanical properties of the fibers. • CNTs were deposited on the aramid fibers, reaching electrical conductivity. • Homogeneous CNT distribution was achieved by using pristine fibers or chlorosulfonic acid. - Abstract: Multiwall carbon nanotubes (MWCNTs) oxidized by an acid treatment were deposited on the surface of as-received commercial aramid fibers containing a surface coating (“sizing”), and fibers modified by either a chlorosulfonic treatment or a mixture of nitric and sulfuric acids. The surface of the aramid fiber activated by the chemical treatments presents increasing density of CO, COOH and OH functional groups. However, these chemical treatments reduced the tensile mechanical properties of the fibers, especially when the nitric and sulfuric acid mixture was used. Characterization of the MWCNTs deposited on the fiber surface was conducted by scanning electron microscopy, Raman spectroscopy mapping and X-ray photoelectron spectroscopy. These characterizations showed higher areal concentration and more homogeneous distribution of MWCNTs over the aramid fibers for as-received fibers and for those modified with chlorosulfonic acid, suggesting the existence of interaction between the oxidized MWCNTs and the fiber coating. The electrical resistance of the MWCNT-modified aramid yarns comprising ∼1000 individual fibers was in the order of MΩ/cm, which renders multifunctional properties.

  5. A modified method for estimation of chemical oxygen demand for samples having high suspended solids.

    Science.gov (United States)

    Yadvika; Yadav, Asheesh Kumar; Sreekrishnan, T R; Satya, Santosh; Kohli, Sangeeta

    2006-03-01

    Determination of chemical oxygen demand (COD) of samples having high suspended solids concentration such as cattle dung slurry with open reflux method of APHA-AWWA-WPCF did not give consistent results. This study presents a modification of the open reflux method (APHA-AWWA-WPCF) to make it suitable for samples with high percentage of suspended solids. The new method is based on a different technique of sample preparation, modified quantities of reagents and higher reflux time as compared to the existing open reflux method. For samples having solids contents of 14.0 g/l or higher, the modified method was found to give higher value of COD with much higher consistency and accuracy as compared to the existing open reflux method.

  6. The Use of Aryl Hydrazide Linkers for the Solid Phase Synthesis of Chemically Modified Peptides

    Energy Technology Data Exchange (ETDEWEB)

    Woo, Y; Mitchell, A R; Camarero, J A

    2006-11-03

    Since Merrifield introduced the concept of solid phase synthesis in 1963 for the rapid preparation of peptides, a large variety of different supports and resin-linkers have been developed that improve the efficiency of peptide assembly and expand the myriad of synthetically feasible peptides. The aryl hydrazide is one of the most useful resin-linkers for the synthesis of chemically modified peptides. This linker is completely stable during Boc- and Fmoc-based solid phase synthesis and yet it can be cleaved under very mild oxidative conditions. The present article reviews the use of this valuable linker for the rapid and efficient synthesis of C-terminal modified peptides, head-to-tail cyclic peptides and lipidated peptides.

  7. Chitosan and chemically modified chitosan beads for acid dyes sorption

    Institute of Scientific and Technical Information of China (English)

    AZLAN Kamari; WAN SAIME Wan Ngah; LAI KEN Liew

    2009-01-01

    The capabilities of chitosan and chitosan-EGDE (ethylene glycol diglycidyl ether) beads for removing Acid Red 37 (AR 37) and Acid Blue 25 (AB 25) from aqueous solution were examined. Chitosan beads were cross-linked with EGDE to enhance its chemical resistance and mechanical strength. Experiments were performed as a function of pH, agitation period and concentration of AR 37 and AB 25. It was shown that the adsorption capacities of chitosan were comparatively higher than chitosan-EGDE for both acid dyes. This is mainly because cross-linking using EGDE reduces the major adsorption sites -NH3+ on chitosan. Langmuir isotherm model showed best conformity compared to Freundlich and BET. The kinetic experimental data agreed very well to the pseudo second-order kinetic model. The desorption study revealed that after three cycles of adsorption and desorption by NaOH and HCl, both adsorbents retained their promising adsorption abilities. FT-IR analysis proved that the adsorption of acid dyes onto chitosan-based adsorbents was a physical adsorption. Results also showed that chitosan and chitosan-EGDE beads were favourable adsorbers and could be employed as low-cost alternatives for the removal of acid dyes in wastewater treatment.

  8. Tannic Acid as a Bio-Based Modifier of Epoxy/Anhydride Thermosets

    OpenAIRE

    Xiaoma Fei; Fangqiao Zhao; Wei Wei; Jing Luo; Mingqing Chen; Xiaoya Liu

    2016-01-01

    Toughening an epoxy resin by bio-based modifiers without trade-offs in its modulus, mechanical strength, and other properties is still a big challenge. This paper presents an approach to modify epoxy resin with tannic acid (TA) as a bio-based feedstock. Carboxylic acid-modified tannic acid (TA–COOH) was first prepared through a simple esterification between TA and methylhexahydrophthalic anhydride, and then used as a modifier for the epoxy/anhydride curing system. Owing to the chemical modifi...

  9. A NOVEL METHOD TO SYNTHESIZE N-DOPED CNTs ARRAYS VIA CHEMICAL MODIFYING POROUS ALUMINA MEMBRANE

    OpenAIRE

    CHENGYONG LI; LEI HE

    2014-01-01

    N-doped carbon nanotubes (CNTs) arrays were fabricated via simply chemical modifying porous alumina membrane (PAM) with dopamine. The diameter of N-doped CNTs is about 60–70 nm. The N/C atomic ratio is calculated to be 0.05 and the main functionality is pyridone/pyrrole N. This chemical modifying method can be used to fabricate mass of N-doped CNTs arrays in one step with single raw material.

  10. a Novel Method to Synthesize N-DOPED CNTs Arrays via Chemical Modifying Porous Alumina Membrane

    Science.gov (United States)

    Li, Chengyong; He, Lei

    2014-01-01

    N-doped carbon nanotubes (CNTs) arrays were fabricated via simply chemical modifying porous alumina membrane (PAM) with dopamine. The diameter of N-doped CNTs is about 60-70 nm. The N/C atomic ratio is calculated to be 0.05 and the main functionality is pyridone/pyrrole N. This chemical modifying method can be used to fabricate mass of N-doped CNTs arrays in one step with single raw material.

  11. Correlation between dynamic wetting behavior and chemical components of thermally modified wood

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Wang; Zhu, Yuan; Cao, Jinzhen, E-mail: caoj@bjfu.edu.cn; Sun, Wenjing

    2015-01-01

    Highlights: • We studied the dynamic wetting behavior of thermally modified wood by wetting models. • We found lower wetting speed of water droplets on thermally modified wood surface. • Dynamic wetting behavior and surface chemical components show a strong correlation. - Abstract: In order to investigate the dynamic wetting behavior of thermally modified wood, Cathay poplar (Populus cathayana Rehd.) and Scots pine (Pinus sylvestris L.) samples were thermally modified in an oven at 160, 180, 200, 220 or 240 °C for 4 h in this study. The dynamic contact angles and droplet volumes of water droplets on modified and unmodified wood surfaces were measured by sessile drop method, and their changing rates (expression index: K value and wetting slope) calculated by wetting models were illustrated for mapping the dynamic wetting process. The surface chemical components were also measured by X-ray photoelectron spectroscopy analysis (XPS), thus the relationship between dynamic wetting behavior and chemical components of thermally modified wood were determined. The results indicated that thermal modification was capable of decreasing the dynamic wettability of wood, expressed in lowing spread and penetration speed of water droplets on wood surfaces. This change was more obvious with the increased heating temperature. The K values varied linearly with the chemical components parameter (mass loss, O/C ratio, and C{sub 1}/C{sub 2} ratio), indicating a strong correlation between dynamic wetting behavior and chemical components of thermally modified wood.

  12. Determination of Human-Health Pharmaceuticals in Filtered Water by Chemically Modified Styrene-Divinylbenzene Resin-Based Solid-Phase Extraction and High-Performance Liquid Chromatography/Mass Spectrometry

    Science.gov (United States)

    Furlong, Edward T.; Werner, Stephen L.; Anderson, Bruce D.; Cahill, Jeffery D.

    2008-01-01

    In 1999, the Methods Research and Development Program of the U.S. Geological Survey National Water Quality Laboratory began the process of developing a method designed to identify and quantify human-health pharmaceuticals in four filtered water-sample types: reagent water, ground water, surface water minimally affected by human contributions, and surface water that contains a substantial fraction of treated wastewater. Compounds derived from human pharmaceutical and personal-care product use, which enter the environment through wastewater discharge, are a newly emerging area of concern; this method was intended to fulfill the need for a highly sensitive and highly selective means to identify and quantify 14 commonly used human pharmaceuticals in filtered-water samples. The concentrations of 12 pharmaceuticals are reported without qualification; the concentrations of two pharmaceuticals are reported as estimates because long-term reagent-spike sample recoveries fall below acceptance criteria for reporting concentrations without qualification. The method uses a chemically modified styrene-divinylbenzene resin-based solid-phase extraction (SPE) cartridge for analyte isolation and concentration. For analyte detection and quantitation, an instrumental method was developed that used a high-performance liquid chromatography/mass spectrometry (HPLC/MS) system to separate the pharmaceuticals of interest from each other and coextracted material. Immediately following separation, the pharmaceuticals are ionized by electrospray ionization operated in the positive mode, and the positive ions produced are detected, identified, and quantified using a quadrupole mass spectrometer. In this method, 1-liter water samples are first filtered, either in the field or in the laboratory, using a 0.7-micrometer (um) nominal pore size glass-fiber filter to remove suspended solids. The filtered samples then are passed through cleaned and conditioned SPE cartridges at a rate of about 15

  13. Facile Synthesis of Mono-Dispersed Polystyrene (PS/Ag Composite Microspheres via Modified Chemical Reduction

    Directory of Open Access Journals (Sweden)

    Wen Zhu

    2013-12-01

    Full Text Available A modified method based on in situ chemical reduction was developed to prepare mono-dispersed polystyrene/silver (PS/Ag composite microspheres. In this approach; mono-dispersed PS microspheres were synthesized through dispersion polymerization using poly-vinylpyrrolidone (PVP as a dispersant at first. Then, poly-dopamine (PDA was fabricated to functionally modify the surfaces of PS microspheres. With the addition of [Ag(NH32]+ to the PS dispersion, [Ag(NH32]+ complex ions were absorbed and reduced to silver nanoparticles on the surfaces of PS-PDA microspheres to form PS/Ag composite microspheres. PVP acted both as a solvent of the metallic precursor and as a reducing agent. PDA also acted both as a chemical protocol to immobilize the silver nanoparticles at the PS surface and as a reducing agent. Therefore, no additional reducing agents were needed. The resulting composite microspheres were characterized by TEM, field emission scanning electron microscopy (FESEM, energy-dispersive X-ray spectroscopy (EDS, XRD, UV-Vis and surface-enhanced Raman spectroscopy (SERS. The results showed that Ag nanoparticles (NPs were homogeneously immobilized onto the PS microspheres’ surface in the presence of PDA and PVP. PS/Ag composite microspheres were well formed with a uniform and compact shell layer and were adjustable in terms of their optical property.

  14. Chemically modified inulin microparticles serving dual function as a protein antigen delivery vehicle and immunostimulatory adjuvant.

    Science.gov (United States)

    Gallovic, Matthew D; Montjoy, Douglas G; Collier, Michael A; Do, Clement; Wyslouzil, Barbara E; Bachelder, Eric M; Ainslie, Kristy M

    2016-03-01

    To develop a new subunit vaccine adjuvant, we chemically modified a naturally-occurring, immunostimulatory inulin polysaccharide to produce an acid-sensitive biopolymer (acetalated inulin, Ace-IN). Various hydrophobic Ace-IN polymers were formed into microparticles (MPs) by oil-in-water emulsions followed by solvent evaporation These Ace-IN MPs possessed tunable degradation characteristics that, unlike polyesters used in FDA-approved microparticulate formulations, had only pH-neutral hydrolytic byproducts. Macrophages were passively targeted with cytocompatible Ace-IN MPs. TNF-α production by macrophages treated with Ace-IN MPs could be altered by adjusting the polymers' chemistry. Mice immunized with Ace-IN MPs encapsulating a model ovalbumin (OVA) antigen showed higher production of anti-OVA IgG antibody levels relative to soluble antigen. The antibody titers were also comparable to an alum-based formulation. This proof-of-concept establishes the potential for chemically-modified inulin MPs to simultaneously enable dual functionality as a stimuli-controlled antigen delivery vehicle and immunostimulatory adjuvant.

  15. DIMENSIONAL STABILITY AND WATER REPELLENT EFFICIENCY MEASUREMENT OF CHEMICALLY MODIFIED TROPICAL LIGHT HARDWOOD

    OpenAIRE

    Md. Saiful Islam; Sinin Hamdan; Mohamad Rusop; Md. Rezaur Rahman; Abu Saleh Ahmed; M. A. M. Mohd Idrus

    2012-01-01

    Chemical modification is an often-followed route to improve physical and mechanical properties of solid wood materials. In this study five kinds of tropical light hardwoods species, namely jelutong (Dyera costulata), terbulan (Endospermum diadenum), batai (Paraserianthes moluccana), rubberwood (Hevea brasiliensis), and pulai (Alstonia pneumatophora), were chemically modified with benzene diazonium salt to improve their dimensional stability and water repellent efficiency. The dimensional stab...

  16. A Modified Vertex—Based Shape Coding Algorithm

    Institute of Scientific and Technical Information of China (English)

    石旭利; 张兆扬

    2002-01-01

    This paper proposes a modified shape coding algorthm called modified vertex-based shape coding(MVBSC) to encode the boundary of a visual object compactly by using a modified polygonal approximation approach which uses modified curvature scale space (CSS) theory to extract feature0points.

  17. The use of modified phenol for chemical face peeling.

    Science.gov (United States)

    Stone, P A

    1998-01-01

    This article reviews the results of 59 consecutive, modified phenol facial peels on 627 anatomic areas for the purpose of reducing fine to coarse rhytides, hyperpigmentation, and actinic keratoses. This work discusses the Venner-Kellson concentrated Lysol saponated formula containing 62.5% phenol; the Maschek-Truppman 53% phenol, nonsaponated glycerin formula; and the previously unpublished Gradé formulae I, II, and III with 49.5%, 60%, and 70% phenol, respectively. The new Stone formulae I, II, and III are introduced here. These new formulae are mixed from available reagents, thus obviating the need to melt potentially toxic phenol crystals, and are designed to achieve a range of clinical peel results on a wide variety of skin types. The ingredients, methods of preparation and application, as well as three postpeel occlusion techniques are presented. Clinical data including pH measurements, croton oil ratios, phenol concentrations, and preliminary biopsy data also are presented.

  18. Radiation modification of swollen and chemically modified cellulose

    Science.gov (United States)

    Borsa, J.; Tóth, T.; Takács, E.; Hargittai, P.

    2003-06-01

    Effect of accessibility of cellulose molecules on development of crosslinks during high-energy irradiation was investigated. Accessibility of cellulose was improved by swelling (NaOH, tetramethylammonium hydroxide), carboxymethylation, coating with water-soluble carboxymethylcellulose, respectively. Irradiation of samples (10 kGy) was carried out in wet state of the fabric as mobility of cellulose molecules is much higher in the presence of water and high mobility of molecular chains is advantageous for development of crosslinks. Change in molecular size was followed by degree of polymerization. The structure modified by crosslinks was characterized by increase in the absorbance assigned to the intermolecular hydrogen bonds (FTIR), and by decrease of fiber swelling (water vapor sorption, water retention). Thew highest values both for water vapor sorption and water retention were found in sample of highest accessibility (carboxymethylated cotton fabric coated with carboxymethylcellulose).

  19. Mthfd1 is a modifier of chemically induced intestinal carcinogenesis.

    Science.gov (United States)

    MacFarlane, Amanda J; Perry, Cheryll A; McEntee, Michael F; Lin, David M; Stover, Patrick J

    2011-03-01

    The causal metabolic pathways underlying associations between folate and risk for colorectal cancer (CRC) have yet to be established. Folate-mediated one-carbon metabolism is required for the de novo synthesis of purines, thymidylate and methionine. Methionine is converted to S-adenosylmethionine (AdoMet), the major one-carbon donor for cellular methylation reactions. Impairments in folate metabolism can modify DNA synthesis, genomic stability and gene expression, characteristics associated with tumorigenesis. The Mthfd1 gene product, C1-tetrahydrofolate synthase, is a trifunctional enzyme that generates one-carbon substituted tetrahydrofolate cofactors for one-carbon metabolism. In this study, we use Mthfd1(gt/+) mice, which demonstrate a 50% reduction in C1-tetrahydrofolate synthase, to determine its influence on tumor development in two mouse models of intestinal cancer, crosses between Mthfd1(gt/+) and Apc(min)(/+) mice and azoxymethane (AOM)-induced colon cancer in Mthfd1(gt/+) mice. Mthfd1 hemizygosity did not affect colon tumor incidence, number or load in Apc(min/+) mice. However, Mthfd1 deficiency increased tumor incidence 2.5-fold, tumor number 3.5-fold and tumor load 2-fold in AOM-treated mice. DNA uracil content in the colon was lower in Mthfd1(gt/+) mice, indicating that thymidylate biosynthesis capacity does not play a significant role in AOM-induced colon tumorigenesis. Mthfd1 deficiency-modified cellular methylation potential, as indicated by the AdoMet: S-adenosylhomocysteine ratio and gene expression profiles, suggesting that changes in the transcriptome and/or decreased de novo purine biosynthesis and associated mutability cause cellular transformation in the AOM CRC model. This study emphasizes the impact and complexity of gene-nutrient interactions with respect to the relationships among folate metabolism and colon cancer initiation and progression.

  20. Chemical and structural effects of base modifications in messenger RNA

    Science.gov (United States)

    Harcourt, Emily M.; Kietrys, Anna M.; Kool, Eric T.

    2017-01-01

    A growing number of nucleobase modifications in messenger RNA have been revealed through advances in detection and RNA sequencing. Although some of the biochemical pathways that involve modified bases have been identified, research into the world of RNA modification -- the epitranscriptome -- is still in an early phase. A variety of chemical tools are being used to characterize base modifications, and the structural effects of known base modifications on RNA pairing, thermodynamics and folding are being determined in relation to their putative biological roles.

  1. WATER-BLOWN POLYURETHANE RIGID FOAMS MODIFIED BY CHEMICAL PLASTICATION

    Institute of Scientific and Technical Information of China (English)

    YU Ming; XU Qiang

    2006-01-01

    Water-blown polyurethane rigid foams are getting more and more attention, because the traditional blowing agent HCFC141b has already been abolished to prevent the ozone layer from destruction. However, the polyurethane rigid foams blown by water have serious defects, i.e. friability and resulting lower adhesion strength. Thus, the purpose of this study is to resolve the problems by chemical plastication. The maleate was added to polyol-premix containing water or to polyisocyanate,with both of which maleate does not react. To prove the reaction when polyol-premix and polyisocyanate were mixed, the model composite was synthesized and analyzed by IR, NMR and ESI (MS). Furthermore, a series of water-blown polyurethane rigid foams added different amount maleate were successfully prepared. By testing impact strength and adhesion strength of the foams, the actual effect of adding maleate was obtained.

  2. CO2 adsorption on chemically modified activated carbon.

    Science.gov (United States)

    Caglayan, Burcu Selen; Aksoylu, A Erhan

    2013-05-15

    CO2 adsorption capacity of a commercial activated carbon was improved by using HNO3 oxidation, air oxidation, alkali impregnation and heat treatment under helium gas atmosphere. The surface functional groups produced were investigated by diffuse reflectance infrared Fourier transform spectrometer (DRIFTS). CO2 adsorption capacities of the samples were determined by gravimetric analyses for 25-200°C temperature range. DRIFTS studies revealed the formation of carboxylic acid groups on the HNO3 oxidized adsorbents. Increased aromatization and uniform distribution of the Na particles were observed on the samples prepared by Na2CO3 impregnation onto HNO3 oxidized AC support. The adsorption capacities of the nonimpregnated samples were increased by high temperature helium treatments or by increasing the adsorption temperature; both leading to decomposition of surface oxygen groups, forming sites that can easily adsorb CO2. The adsorption capacity loss due to cyclic adsorption/desorption procedures was overcome with further surface stabilization of Na2CO3 modified samples with high temperature He treatments. With Na2CO3 impregnation the mass uptakes of the adsorbents at 20 bars and 25 °C were improved by 8 and 7 folds and at 1 bar were increased 15 and 16 folds, on the average, compared to their air oxidized and nitric acid oxidized supports, respectively.

  3. Basic analytical investigation of plasma-chemically modified carbon fibers

    Energy Technology Data Exchange (ETDEWEB)

    Bubert, H.; Ai, X.; Haiber, S.; Heintze, M.; Brueser, V.; Pasch, E.; Brandl, W.; Marginean, G

    2002-10-15

    The background of the present investigation is to enhance the overall adherence of vapor grown carbon fibers (VGCF) to the surrounding polymer matrix in different applications by forming polar groups at their surfaces and by modifying the surface morphology. This has been done by plasma treatments using a low-pressure plasma with different gases, flow rates, pressures and powers. Two different types of carbon fibers were investigated: carbon microfibers and carbon nanofibers. The characterization of fiber surfaces was achieved by photoelectron spectroscopy (XPS), contact angle measurements and titration. These investigations were accompanied by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The oxygen plasma treatment of the fibers changes the surfaces by forming a layer with a thickness of the order of one nanometer mainly consisting of functional groups like hydroxyl, carbonyl and carboxyl. After functionalization of the complete surface, a further plasma treatment does not enhance the superficial oxygen content but changes slightly the portions of the functional groups. A comparison of the methods applied provides a largely consistent image of the effect of plasma treatment.

  4. Biosorption of Methylene Blue by Chemically Modified Cellulose Waste

    Institute of Scientific and Technical Information of China (English)

    JIN Yanqiao; ZHANG Yizhuan; Lü Qiufeng; CHENG Xiansu

    2014-01-01

    Citric acid modified cellulose waste (CMCW) was prepared via esterification and used as a low-cost biosorbent for the removal of methylene blue (MB) from aqueous solutions. The effects of biosorbent concentration, initial pH of MB solution, biosorption temperature, contact time, and initial MB concentration on the biosorption of MB were investigated using batch biosorption technique under static conditions. The experimental results showed that CMCW exhibited excellent biosorption characteristics for MB. The maximum biosorption capacity of MB was up to 214.5 mg/g at an adsorption temperature of 293 K. The removal rate of MB onto CMCW reached the maximum at pH>4 and the biosorption reached an equilibrium at about 50 min. The kinetic data can be described well with the pseudo-second-order model and the isotherm data was found to fit the Langmuir isotherm with a monolayer adsorption capacity of 211.42 mg/g. The biosorption appears to be controlled by chemisorption and may be involved in surface adsorption and pore diffusion during the whole biosorption process.

  5. Interactions of zearalenone with native and chemically modified cyclodextrins and their potential utilization.

    Science.gov (United States)

    Poór, Miklós; Kunsági-Máté, Sándor; Sali, Nikolett; Kőszegi, Tamás; Szente, Lajos; Peles-Lemli, Beáta

    2015-10-01

    Zearalenone (ZEA) is a widespread xenoestrogenic mycotoxin produced by several Fusarium species. ZEA can cause reproductive disorders in farm animals and hyperoestrogenic syndromes in humans; therefore, development of more sensitive analytical methods (to quantify the mycotoxin) as well as strategies for prevention of its toxic impacts is highly important. In this study, the interactions of ZEA with native and chemically modified cyclodextrins (CDs) were investigated using fluorescence spectroscopy. Furthermore, in vitro experiments on liver cells were also performed to test the potential effect of CDs on toxin uptake. Our results demonstrate that ZEA forms stable complexes with CDs (logK values are approximately 3.7-4.7) resulting in the considerable elevation of its fluorescence signal. In addition, some of the CDs show ability to inhibit the cellular uptake of ZEA, suggesting their potential suitability to develop new CD-based preventive/detoxification strategies against ZEA in the future. Copyright © 2015 Elsevier B.V. All rights reserved.

  6. Fabrication of Rare Earth-Doped Transparent Glass Ceramic Optical Fibers by Modified Chemical Vapor Deposition

    CERN Document Server

    Blanc, Wilfried; Nguyen, Luan; Bhaktha, S N B; Sebbah, Patrick; Pal, Bishnu P; Dussardier, Bernard

    2011-01-01

    Rare earth (RE) doped silica-based optical fibers with transparent glass ceramic (TGC) core was fabricated through the well-known modified chemical vapor deposition (MCVD) process without going through the commonly used stage of post-ceramming. The main characteristics of the RE-doped oxyde nanoparticles namely, their density and mean diameter in the fibers are dictated by the concentration of alkaline earth element used as phase separating agent. Magnesium and erbium co-doped fibers were fabricated. Optical transmission in term of loss due to scattering as well as some spectroscopic characteristics of the erbium ions was studied. For low Mg content, nano-scale particles could be grown with and relatively low scattering losses were obtained, whereas large Mg-content causes the growth of larger particles resulting in much higher loss. However in the latter case, certain interesting alteration of the spectroscopic properties of the erbium ions were observed. These initial studies should be useful in incorporati...

  7. Dual-tracer method to estimate coral reef response to a plume of chemically modified seawater

    Science.gov (United States)

    Maclaren, J. K.; Caldeira, K.

    2013-12-01

    We present a new method, based on measurement of seawater samples, to estimate the response of a reef ecosystem to a plume of an additive (for example, a nutrient or other chemical). In the natural environment, where there may be natural variability in concentrations, it can be difficult to distinguish between changes in concentrations that would occur naturally and changes in concentrations that result from a chemical addition. Furthermore, in the unconfined natural environment, chemically modified water can mix with waters that have not been modified, making it difficult to distinguish between effects of dilution and effects of chemical fluxes or transformations. We present a dual-tracer method that extracts signals from observations that may be affected by both natural variability and dilution. In this dual-tracer method, a substance (in our example case, alkalinity) is added to the water in known proportion to a passive conservative tracer (in our example case, Rhodamine WT dye). The resulting plume of seawater is allowed to flow over the study site. Two transects are drawn across the plume at the front and back of the study site. If, in our example, alkalinity is plotted as a function of dye concentration for the front transect, the slope of the resulting mixing line is the ratio of alkalinity to dye in the added fluid. If a similar mixing line is measured and calculated for the back transect, the slope of this mixing line will indicate the amount of added alkalinity that remains in the water flowing out of the study site per unit of added dye. The ratio of the front and back slopes indicates the fraction of added alkalinity that was taken up by the reef. The method is demonstrated in an experiment performed on One Tree Reef (Queensland, Australia) aimed at showing that ocean acidification is already affecting coral reef growth. In an effort to chemically reverse some of the changes to seawater chemistry that have occurred over the past 200 years, we added

  8. Innate Immune and Chemically Triggered Oxidative Stress Modifies Translational Fidelity

    Science.gov (United States)

    Netzer, Nir; Goodenbour, Jeffrey M.; David, Alexandre; Dittmar, Kimberly A.; Jones, Richard B.; Schneider, Jeffrey R.; Boone, David; Eves, Eva M.; Rosner, Marsha R.; Gibbs, James S.; Embry, Alan; Dolan, Brian; Das, Suman; Hickman, Heather; Berglund, Peter; Bennink, Jack R.; Yewdell, Jonathan W.; Pan, Tao

    2009-01-01

    Translational fidelity, essential for protein and cell function, requires accurate tRNA aminoacylation. Purified aminoacyl-tRNA synthetases exhibit a fidelity of 1 error per 10,000 to 100,000 couplings 1, 2. The accuracy of tRNA aminoacylation in vivo is uncertain, however, and might be considerably lower 3–6. Here, we show that in mammalian cells, approximately 1% of methionine (Met) residues used in protein synthesis are aminoacylated to non-methionyl-tRNAs. Remarkably, Met-misacylation increases up to 10-fold upon exposing cells to live or non-infectious viruses, toll-like receptor ligands, or chemically induced oxidative stress. Met is misacylated to specific non-methionyl-tRNA families, and these Met-misacylated tRNAs are used in translation. Met-misacylation is blocked by an inhibitor of cellular oxidases, implicating reactive oxygen species (ROS) as the misacylation trigger. Among six amino acids tested, tRNA misacylation occurs exclusively with Met. As Met residues are known to protect proteins against ROS-mediated damage 7, we propose that Met-misacylation functions adaptively to increase Met incorporation into proteins to protect cells against oxidative stress. In demonstrating an unexpected conditional aspect of decoding mRNA, our findings illustrate the importance of considering alternative iterations of the genetic code. PMID:19940929

  9. Mechanical and chemical properties of cysteine-modified kinesin molecules.

    Science.gov (United States)

    Iwatani, S; Iwane, A H; Higuchi, H; Ishii, Y; Yanagida, T

    1999-08-10

    To probe the structural changes within kinesin molecules, we made the mutants of motor domains of two-headed kinesin (4-411 aa) in which either all the five cysteines or all except Cys45 were mutated. A residual cysteine (Cys45) of the kinesin mutant was labeled with an environment-sensitive fluorescent probe, acrylodan. ATPase activity, mechanical properties, and fluorescence intensity of the mutants were measured. Upon acrylodan-labeled kinesin binding to microtubules in the presence of 1 mM AMPPNP, the peak intensity was enhanced by 3.4-fold, indicating the structural change of the kinesin head by the binding. Substitution of cysteines decreased both the maximum microtubule-activated ATPase and the sliding velocity to the same extent. However, the maximum force and the step size were not affected; the force produced by a single molecule was 6-6.5 pN, and a step size due to the hydrolysis of one ATP molecule by kinesin molecules was about 10 nm for all kinesins. This step size was close to a unitary step size of 8 nm. Thus, the mechanical events of kinesin are tightly coupled with the chemical events.

  10. Direct determination of cadmium in Orujo spirit samples by electrothermal atomic absorption spectrometry: Comparative study of different chemical modifiers

    Energy Technology Data Exchange (ETDEWEB)

    Vilar Farinas, M. [Departamento de Quimica Analitica, Nutricion y Bromatologia, Facultad de Ciencias, Universidad de Santiago de Compostela, Campus de Lugo, 27002 Lugo (Spain); Barciela Garcia, J. [Departamento de Quimica Analitica, Nutricion y Bromatologia, Facultad de Ciencias, Universidad de Santiago de Compostela, Campus de Lugo, 27002 Lugo (Spain); Garcia Martin, S. [Departamento de Quimica Analitica, Nutricion y Bromatologia, Facultad de Ciencias, Universidad de Santiago de Compostela, Campus de Lugo, 27002 Lugo (Spain); Pena Crecente, R. [Departamento de Quimica Analitica, Nutricion y Bromatologia, Facultad de Ciencias, Universidad de Santiago de Compostela, Campus de Lugo, 27002 Lugo (Spain); Herrero Latorre, C. [Departamento de Quimica Analitica, Nutricion y Bromatologia, Facultad de Ciencias, Universidad de Santiago de Compostela, Campus de Lugo, 27002 Lugo (Spain)]. E-mail: cherrero@lugo.usc.es

    2007-05-22

    In this work, several analytical methods are proposed for cadmium determination in Orujo spirit samples using electrothermal atomic absorption spectrometry (ETAAS). Permanent chemical modifiers thermally coated on the platforms inserted in pyrolytic graphite tubes (such as W, Ir, Ru, W-Ir and W-Ru) were comparatively studied in relation to common chemical modifier mixtures [Pd-Mg(NO{sub 3}){sub 2} and (NH{sub 4})H{sub 2}PO{sub 4}-Mg(NO{sub 3}){sub 2}] for cadmium stabilization. Different ETAAS Cd determination methods based on the indicated modifiers have been developed. In each case, pyrolysis and atomization temperatures, atomization shapes, characteristic masses and detection limits as well as other analytical characteristics have been determined. All the assayed modifiers (permanent and conventional) were capable of achieving the appropriate stabilization of the analyte, with the exception of Ru and W-Ru. Moreover, for all developed methods, recoveries (99-102%) and precision (R.S.D. lower than 10%) were acceptable. Taking into account the analytical performance (best detection limit LOD = 0.01 {mu}g L{sup -1}), the ETAAS method based on the use of W as a permanent modifier was selected for further direct Cd determinations in Orujo samples from Galicia (NW Spain). The chosen method was applied in the determination of the Cd content in 38 representative Galician samples. The cadmium concentrations ranged

  11. Chemically and biologically modified activated carbon sorbents for the removal of lead ions from aqueous media.

    Science.gov (United States)

    Mahmoud, Mohamed E; Abdel-Fattah, Tarek M; Osman, Maher M; Ahmed, Somia B

    2012-01-01

    A method is described for hybridization of the adsorption and biosorption characteristics of chemically treated commercial activated carbon and baker's yeast, respectively, for the formation of environmental friendly multifunctional sorbents. Activated carbon was loaded with baker's yeast after acid-base treatment. Scanning Electron Microscopy (SEM) and Fourier Transform Infrared (FTIR) Spectroscopy were used to characterize these sorbents. Moreover, the sorption capabilities for lead (II) ions were evaluated. A value of 90 μmol g(-1) was identified as the maximum sorption capacity of activated carbon. Acid-base treatment of activated carbon was found to double the sorption capacity (140-180 μmol g(-1)). Immobilization of baker's yeast on the surface of activated carbon sorbents was found to further improve the sorption capacity efficiency of lead to 360, 510 and 560 μmol g(-1), respectively. Several important factors such as pH, contact time, sorbent dose, lead concentration and interfering ions were examined. Lead sorption process was studied and evaluated by several adsorption isotherms and found to follow the Langmuir and BET models. The potential applications of various chemically and biologically modified sorbents and biosorbents for removal of lead from real water matrices were also investigated via multistage micro-column technique and the results referred to excellent recovery values of lead (95.0-99.0 ± 3.0-5.0 %).

  12. Fretting Wear Behavior of Medium Carbon Steel Modified by Low Temperature Gas Multi-component Thermo-chemical Treatment

    Institute of Scientific and Technical Information of China (English)

    LUO Jun; ZHENG Jianfeng; PENG Jinfang; HE Liping; ZHU Minhao

    2010-01-01

    The introduction of surface engineering is expected to be an effective strategy against fretting damage. A large number of studies show that the low gas multi-component (such as carbon, nitrogen, sulphur and oxygen, etc) thermo-chemical treatment(LTGMTT) can overcome the brittleness of nitriding process, and upgrade the surface hardness and improve the wear resistance and fatigue properties of the work-pieces significantly. However, there are few reports on the anti-fretting properties of the LTGMTT modified layer up to now, which limits the applications of fretting. So this paper discusses the fretting wear behavior of modified layer on the surface of LZ50 (0.48%C) steel prepared by low temperature gas multi-component thermo-chemical treatment (LTGMTT) technology. The fretting wear tests of the modified layer flat specimens and its substrate (LZ50 steel) against 52100 steel balls with diameter of 40 mm are carried out under normal load of 150 N and displacement amplitudes varied from 2 μm to 40 μm. Characterization of the modified layer and dynamic analyses in combination with microscopic examinations were performed through the means of scanning electron microscope(SEM), optical microscope(OM), X-ray diffraction(XRD) and surface profilometer. The experimental results showed that the modified layer with a total thickness of 60 μm was consisted of three parts, i.e., loose layer, compound layer and diffusion layer. Compared with the substrate, the range of the mixed fretting regime(MFR) of the LTGMTT modified layer diminished, and the slip regime(SR) of the modified layer shifted to the direction of smaller displacement amplitude. The coefficient of friction(COF) of the modified layer was lower than that of the substrate in the initial stage. For the modified layer, the damage in partial slip regime(PSR) was very slight. The fretting wear mechanism of the modified layer both in MFR and SR was abrasive wear and delamination. The modified layer presented better wear

  13. Food preparation characteristics of potato starch pastes containing a proportion of chemically-modified starch

    OpenAIRE

    菊地, 和美; 高橋 セツ子; 吉田 訓子; 山本 未穂; 知地 英征; Kazumi, KIKUCHI; Takahashi, Setsuko; Yoshida, Kuniko; Yamamoto, Miho; Chiji, Hideyuki; 藤女子大学人間生活学部食物栄養学科; 藤女子大学人間生活学部食物栄養学科藤女子大学大学院人間生活学研究科食物栄養学専攻

    2011-01-01

    Hokkaido potatoes are widely used as a source of starch. Potato starch is used for various purposes,particularly for the production of fish paste products,livestock products, and confectionery. Moreover, modified starch, which is produced by processing potato starch chemically and physically, is used in a variety of forms. This study examines the properties of modified starch gels produced by further enhancing the starch functions of potato starch. To study the primary properties of starch ge...

  14. Correlation between dynamic wetting behavior and chemical components of thermally modified wood

    Science.gov (United States)

    Wang, Wang; Zhu, Yuan; Cao, Jinzhen; Sun, Wenjing

    2015-01-01

    In order to investigate the dynamic wetting behavior of thermally modified wood, Cathay poplar (Populus cathayana Rehd.) and Scots pine (Pinus sylvestris L.) samples were thermally modified in an oven at 160, 180, 200, 220 or 240 °C for 4 h in this study. The dynamic contact angles and droplet volumes of water droplets on modified and unmodified wood surfaces were measured by sessile drop method, and their changing rates (expression index: K value and wetting slope) calculated by wetting models were illustrated for mapping the dynamic wetting process. The surface chemical components were also measured by X-ray photoelectron spectroscopy analysis (XPS), thus the relationship between dynamic wetting behavior and chemical components of thermally modified wood were determined. The results indicated that thermal modification was capable of decreasing the dynamic wettability of wood, expressed in lowing spread and penetration speed of water droplets on wood surfaces. This change was more obvious with the increased heating temperature. The K values varied linearly with the chemical components parameter (mass loss, O/C ratio, and C1/C2 ratio), indicating a strong correlation between dynamic wetting behavior and chemical components of thermally modified wood.

  15. Synthesis and optoelectronic properties of chemically modified bi-fluorenylidenes

    OpenAIRE

    Wielopolski, Mateusz; Marszalek, Magdalena; Brunetti, Fulvio G.; Joly, Damien; Calbo, Joaquín; Aragó, Juan; Moser, Jacques-E.; Humphry-Baker, Robin; Zakeeruddin, Shaik M.; Delgado, Juan Luis; Grätzel, Michael; Ortí, Enrique; Martín,Nazario

    2016-01-01

    The development of new light harvesting materials is a key issue for the progress of the research on organic & hybrid photovoltaics. Here, we report a new class of organic sensitizers based on the bi-fluorenylidene moiety as p-linker within the donor–p-linker–acceptor (D–p–A) scheme. The new dyes are endowed with electron donor and electron acceptor units at strategic positions in order to improve their electronic and light-harvesting properties. The comprehensive study of these compounds thr...

  16. Applicability of chemically modified capillaries in chiral capillary electrophoresis for methamphetamine profiling.

    Science.gov (United States)

    Iwata, Yuko T; Mikuma, Toshiyasu; Kuwayama, Kenji; Tsujikawa, Kenji; Miyaguchi, Hajime; Kanamori, Tatsuyuki; Inoue, Hiroyuki

    2013-03-10

    We examined the applicability of chemically modified capillaries on the chiral capillary electrophoresis of essential compounds for methamphetamine (MA) profiling (MA, amphetamine, ephedrine, pseudoephedrine, norephedrine, and norpseudoephedrine) using highly sulfated γ-cyclodextrin as a chiral selector. Four types of chemically modified capillaries, namely, FunCap-CE/Type D (possessing diol groups), Type A (amino groups), Type C (carboxyl groups), and Type S (sulfate groups), were evaluated. Repeatability, speed, and good chiral resolution sufficient for routine MA profiling were achieved with the Type S capillary.

  17. Evaluating Zeolite-Modified Sensors: towards a faster set of chemical sensors

    Science.gov (United States)

    Berna, A. Z.; Vergara, A.; Trincavelli, M.; Huerta, R.; Afonja, A.; Parkin, I. P.; Binions, R.; Trowell, S.

    2011-09-01

    The responses of zeolite-modified sensors, prepared by screen printing layers of chromium titanium oxide (CTO), were compared to unmodified tin oxide sensors using amplitude and transient responses. For transient responses we used a family of features, derived from the exponential moving average (EMA), to characterize chemo-resistive responses. All sensors were tested simultaneously against 20 individual volatile compounds from four chemical groups. The responses of the two types of sensors showed some independence. The zeolite-modified CTO sensors discriminated compounds better using either amplitude response or EMA features and CTO-modified sensors also responded three times faster.

  18. Chemical treatment of the intra-canal dentin surface: a new approach to modify dentin hydrophobicity

    Directory of Open Access Journals (Sweden)

    Cesar GAITAN-FONSECA

    2013-01-01

    Full Text Available Objective This study evaluated the hydrophobicity of dentin surfaces that were modified through chemical silanization with octadecyltrichlorosilane (OTS. Material and Methods An in vitro experimental study was performed using 40 human permanent incisors that were divided into the following two groups: non-silanized and silanized. The specimens were pretreated and chemically modified with OTS. After the chemical modification, the dentin hydrophobicity was examined using a water contact angle measurement (WCA. The effectiveness of the modification of hydrophobicity was verified by the fluid permeability test (FPT. Results and Conclusions Statistically significant differences were found in the values of WCA and FPT between the two groups. After silanization, the hydrophobic intraradicular dentin surface exhibited in vitro properties that limit fluid penetration into the sealed root canal. This chemical treatment is a new approach for improving the sealing of the root canal system.

  19. Modified clay minerals efficiency against chemical and biological warfare agents for civil human protection.

    Science.gov (United States)

    Plachá, Daniela; Rosenbergová, Kateřina; Slabotínský, Jiří; Kutláková, Kateřina Mamulová; Studentová, Soňa; Martynková, Gražyna Simha

    2014-04-30

    Sorption efficiencies of modified montmorillonite and vermiculite of their mono ionic Na and organic HDTMA and HDP forms were studied against chemical and biological warfare agents such as yperite and selected bacterial strains. Yperite interactions with modified clay minerals were observed through its capture in low-density polyethylene foil-modified clay composites by measuring yperite gas permeation with using chemical indication and gas chromatography methods. The antibacterial activities of synthetized organoclays were tested against selected Gram-positive and Gram-negative bacterial species in minimum inhibitory concentration tests. The obtained results showed a positive influence of modified clay minerals on the significant yperite breakthrough-time increase. The most effective material was the polyethylene-Na form montmorillonite, while the polyethylene-Na form vermiculite showed the lowest efficiency. With increasing organic cations loading in the interlayer space the montmorillonite efficiency decreased, and in the case of vermiculite an opposite effect was observed. Generally the modified montmorillonites were more effective than modified vermiculites. The HDP cations seem to be more effective compare to the HDTMA. The antibacterial activity tests confirmed efficiency of all organically modified clay minerals against Gram-positive bacteria. The confirmation of antibacterial activity against Y. pestis, plague bacteria, is the most interesting result of this part of the study.

  20. X-Ray Photoelectron Spectroscopic Characterization of Chemically Modified Electrodes Used as Chemical Sensors and Biosensors: A Review

    Directory of Open Access Journals (Sweden)

    Elio Desimoni

    2015-04-01

    Full Text Available The characterization of chemically modified sensors and biosensors is commonly performed by cyclic voltammetry and electron microscopies, which allow verifying electrode mechanisms and surface morphologies. Among other techniques, X-ray photoelectron spectroscopy (XPS plays a unique role in giving access to qualitative, quantitative/semi-quantitative and speciation information concerning the sensor surface. Nevertheless, XPS remains rather underused in this field. The aim of this paper is to review selected articles which evidence the useful performances of XPS in characterizing the top surface layers of chemically modified sensors and biosensors. A concise introduction to X-ray Photoelectron Spectroscopy gives to the reader the essential background. The application of XPS for characterizing sensors suitable for food and environmental analysis is highlighted.

  1. High-affinity integration of hydroxyapatite nanoparticles with chemically modified silk fibroin

    Energy Technology Data Exchange (ETDEWEB)

    Wang Li; Li Chunzhong [East China University of Science and Technology, Key Laboratory for Ultrafine Materials of Ministry of Education, School of Materials Science and Engineering (China)], E-mail: czli@ecust.edu.cn; Senna, Mamoru [Keio University, Department of Applied Chemistry, Faculty of Science and Technology (Japan)

    2007-10-15

    Hydroxyapatite (HA)-based nanocomposites were prepared by a co-precipitation method with silk fibroin (SF) serving as organic matrix. Silk fibroin was chemically modified with an alkali solution or an enzyme attempting to improve the interface between the mineral and the organic matrix. The influences of the alkali and enzyme pretreatments on microstructure and physicochemical properties of HA-SF composite were examined and compared. The results reveal that both the two kinds of pretreatments facilitate the formation of highly ordered three-dimensional porous network throughout the composites, increase the microhardness of the composite, and promote the preferential growth of HA crystallites along c-axis. Among all the as-prepared samples, the composite containing the enzyme pretreated SF shows desirable hierarchical microstructure with higher degree of organization and more uniform pore size distribution. Due to the enzyme pretreatment, HA crystallites undergo obvious changes in morphology from rod-like to whisker-like and in crystal growth towards more apparent epitaxy along c-axis. The alkali pretreatment induces the stronger chemical interactions between HA and SF and thus to strengthen the inorganic-organic interfacial adhesion. The newly developed HA-SF composites are expected to be attractive biomedical materials for bone repair and remodeling.

  2. Selective recovery of precious metals by persimmon waste chemically modified with dimethylamine.

    Science.gov (United States)

    Xiong, Ying; Adhikari, Chaitanya Raj; Kawakita, Hidetaka; Ohto, Keisuke; Inoue, Katsutoshi; Harada, Hiroyuki

    2009-09-01

    Persimmon waste was chemically modified with dimethylamine (DMA) to obtain a tertiary-amine-type gel, named DMA persimmon waste gel (DMA-PW). It was found to be effective for the adsorption of Au(III), Pd(II), and Pt(IV) in hydrochloric acid medium. In contrast, base metals such as Cu(II), Zn(II), Fe(III), and Ni(II) were not practically adsorbed. The formation of ion pairs of the metal chloro complex anions with the protonated adsorption gels was proposed as the main adsorption process. The gel exhibited selectivity only for precious metals with a remarkably high capacity for Au(III), i.e., 5.63 mol/kg dry gel and comparable capacities, i.e., 0.42 and 0.28 mol/kg for Pd(II) and Pt(IV), respectively. According to the kinetic and electrochemical studies, the adsorption rate of Au(III) was greatly enhanced by the chemical modification. Also, its excellent adsorption characteristics for the precious metals were confirmed by adsorption and elution tests using a column packed with the DMA-PW gel.

  3. Growth of aligned ZnO nanowires via modified atmospheric pressure chemical vapor deposition

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Yuping; Li, Chengchen [Faculty of Science, Jiangsu University, Zhenjiang, Jiangsu, 212013 (China); Chen, Mingming, E-mail: andychain@live.cn [Faculty of Science, Jiangsu University, Zhenjiang, Jiangsu, 212013 (China); Yu, Xiao; Chang, Yunwei [Faculty of Science, Jiangsu University, Zhenjiang, Jiangsu, 212013 (China); Chen, Anqi [State Key Laboratory of Optoelectronic Materials and Technologies, School of Electronics & Information Technology, Sun Yat-Sen University, Guangzhou Higher Education Mega Center (University Town), Guangzhou, 510006 (China); Zhu, Hai, E-mail: zhuhai5@mail.sysu.edu.cn [State Key Laboratory of Optoelectronic Materials and Technologies, School of Electronics & Information Technology, Sun Yat-Sen University, Guangzhou Higher Education Mega Center (University Town), Guangzhou, 510006 (China); Tang, Zikang, E-mail: zktang@umac.mo [State Key Laboratory of Optoelectronic Materials and Technologies, School of Electronics & Information Technology, Sun Yat-Sen University, Guangzhou Higher Education Mega Center (University Town), Guangzhou, 510006 (China); The Institute of Applied Physics and Materials Engineering, University of Macau, Avenida da Universidade, Taipa, Macau (China)

    2016-12-09

    In this work, we report the growth of high-quality aligned ZnO nanowires via a facile atmospheric pressure chemical vapor deposition (CVD) method. The CVD reactor chamber used was more complicated than a conventional one due to the quartz boats loaded with sources (ZnO/C) and substrates being inserted into a semi-open quartz tube, and then placed inside the CVD reactor. The semi-open quartz tube played a very important role in growing the ZnO nanowires, and demonstrated that the transportation properties of Zn and O vapor differ from those in the conventional CVD reactor chamber. Aligned ZnO nanowires were successfully obtained, though they were only found at substrates located upstream. The very high crystalline quality of the obtained ZnO nanowires was demonstrated by high-resolution transmission electron microscopy and room temperature photoluminescence investigations. Such ZnO nanowires with high crystalline quality may provide opportunities for the fabrication of ZnO-based nano-devices in future. - Highlights: • High-quality aligned ZnO nanowires were obtained via modified chemical vapor deposition under atmospheric pressure. • The semi-open quartz tube plays very important roles in growing ZnO nanowires. • The transportation properties of Zn and O vapor differ from those in the conventional CVD reactor chamber.

  4. Chemically modified tetracyclines stimulate matrix metalloproteinase-2 production by periodontal ligament cells.

    NARCIS (Netherlands)

    Bildt, M.M.; Snoek-van Beurden, A.M.; Groot, J. de; El, B. van; Kuijpers-Jagtman, A.M.; Hoff, J.W. Von den

    2006-01-01

    BACKGROUND AND OBJECTIVE: The purpose of this study was to investigate the effects of chemically modified tetracyclines (CMTs) on the production of gelatinases [matrix metalloproteinase (MMP)-2 and -9] by human periodontal ligament (PDL) cells, and on the activity of recombinant gelatinases. MATERIA

  5. Chemical modifiers in electrothermal atomic absorption determination of Platinum and Palladium containing preparations in blood serum

    Directory of Open Access Journals (Sweden)

    Аntonina Alemasova

    2012-11-01

    Full Text Available The biological liquids matrixes influence on the characteristic masses and repeatability of Pt and Pd electrothermal atomic absorption spectroscopy (ETAAS determination was studied. The chemical modifiers dimethylglyoxime and ascorbic acid for matrix interferences elimination and ETAAS results repeatability improvement were proposed while bioliquids ETAAS analysis, and their action mechanism was discussed.

  6. A Novel Chemically Modified Curcumin Reduces Severity of Experimental Periodontal Disease in Rats: Initial Observations

    Directory of Open Access Journals (Sweden)

    Muna S. Elburki

    2014-01-01

    Full Text Available Tetracycline-based matrix metalloproteinase- (MMP- inhibitors are currently approved for two inflammatory diseases, periodontitis and rosacea. The current study addresses the therapeutic potential of a novel pleiotropic MMP-inhibitor not based on an antibiotic. To induce experimental periodontitis, endotoxin (LPS was repeatedly injected into the gingiva of rats on one side of the maxilla; the contralateral (control side received saline injections. Two groups of rats were treated by daily oral intubation with a chemically modified curcumin, CMC 2.24, for two weeks; the control groups received vehicle alone. After sacrifice, gingiva, blood, and maxilla were collected, the jaws were defleshed, and periodontal (alveolar bone loss was quantified morphometrically and by μ-CT scan. The gingivae were pooled per experimental group, extracted, and analyzed for MMPs (gelatin zymography; western blot and for cytokines (e.g., IL-1β; ELISA; serum and plasma samples were analyzed for cytokines and MMP-8. The LPS-induced pathologically excessive bone loss was reduced to normal levels based on either morphometric (P=0.003 or μ-CT (P=0.008 analysis. A similar response was seen for MMPs and cytokines in the gingiva and blood. This initial study, on a novel triketonic zinc-binding CMC, indicates potential efficacy on inflammatory mediators and alveolar bone loss in experimental periodontitis and warrants future therapeutic and pharmacokinetic investigations.

  7. Biomechanical properties of acellular sciatic nerves treated with a modified chemical method

    Institute of Scientific and Technical Information of China (English)

    Xinlong Ma; Zhao Yang; Xiaolei Sun; Jianxiong Ma; Xiulan Li; Zhenzhen Yuan; Yang Zhang; Honggang Guo

    2011-01-01

    Nerve grafts are able to adapt to surrounding biomechanical environments if the nerve graft itself exhibits appropriate biomechanical properties (load, elastic modulus, etc.). The present study was designed to determine the differences in biomechanical properties between fresh and chemically acellularized sciatic nerve grafts. Two different chemical methods were used to establish acellular nerve grafts. The nerve was chemically extracted in the Sondell method with a combination of Triton X-100 (nonionic detergent) and sodium deoxycholate (anionic detergent), and in the modified method with a combination of Triton X-200 (anionic detergent), sulfobetaine-10 (SB-10, amphoteric detergents), and sulfobetaine-16 (SB-16, amphoteric detergents). Following acellularization, hematoxylin-eosin staining and scanning electron microscopy demonstrated that the effect of acellularization via the modified method was similar to the traditional Sondell method. However, effects of demyelination and nerve fiber tube integrity were superior to the traditional Sondell method. Biomechanical testing showed that peripheral nerve graft treated using the chemical method resulted in decreased biomechanical properties (ultimate load, ultimate stress, ultimate strain, and mechanical work to fracture) compared with fresh nerves, but the differences had no statistical significance (P > 0.05). These results demonstrated no significant effect on biomechanical properties of nerves treated using the chemical method. In conclusion, nerve grafts treated via the modified method removed Schwann cells, preserved neural structures, and ensured biomechanical properties of the nerve graft, which could be more appropriate for implantation studies.

  8. Adsorption Studies of Phenol Using Thermally and Chemically Modified Rice Husk as Adsorbents

    Directory of Open Access Journals (Sweden)

    *M. M. Yousaf

    2014-03-01

    Full Text Available Most of the Phenols are hazardous substances and some are supposed to have carcinogenic activity. Thus it is necessary to remove Phenolics and other aromatics from the aqueous ecosystem. Traditional processes for the removal of Phenolics compounds are extraction, adsorption on granulated activated carbon, steam distillation, chemical and bacterial techniques. Literature survey show a number of methods like oxidation, ion exchange, reverse osmosis, electrochemical oxidation and adsorption. Phenol removal by process like, adsorption is the best method of choice as it can remove most of phenols in simple and easy way. In recent past; agricultural by-products such as, maize cob, date stone, apricot Stones, rice bran, and bagass pith have been extensively studied and used as adsorbents for the adsorption of hazardous substances from wastewater. In the present study we tried modified rice husks as potential adsorbents for the removal of Phenol from aqueous system. Batch mode studies were carried out. Isotherm data was generated and fitted in Freundlich and Langmuir equation to explain the phenomenon of adsorption. The adsorption capacities based on Langmuir model (Qm of the 3 adsorbents were found to be 0.81 for raw husk (RH, 0.395 for the Grafted (G and 2.306 mg/g for the Charred (C. The R2 values were 0.92 for raw husk, 0.97 for grafted and 0.91 for charred husk. Based on Freundlich model the adsorption capacities (K were 2.94, 2.29 and 1.25mg/g for Raw husk, grafted husk and charred husk. The R2 values were found to be 0.72, 0.95 and 0.83 for the raw husk, grafted husk and charred husk respectively. Our result showed that modified rice husks could be used as potential adsorbents for Phenol removal from aqueous system.

  9. Chemical and Conformational Diversity of Modified Nucleosides Affects tRNA Structure and Function

    Directory of Open Access Journals (Sweden)

    Ville Y. P. Väre

    2017-03-01

    Full Text Available RNAs are central to all gene expression through the control of protein synthesis. Four major nucleosides, adenosine, guanosine, cytidine and uridine, compose RNAs and provide sequence variation, but are limited in contributions to structural variation as well as distinct chemical properties. The ability of RNAs to play multiple roles in cellular metabolism is made possible by extensive variation in length, conformational dynamics, and the over 100 post-transcriptional modifications. There are several reviews of the biochemical pathways leading to RNA modification, but the physicochemical nature of modified nucleosides and how they facilitate RNA function is of keen interest, particularly with regard to the contributions of modified nucleosides. Transfer RNAs (tRNAs are the most extensively modified RNAs. The diversity of modifications provide versatility to the chemical and structural environments. The added chemistry, conformation and dynamics of modified nucleosides occurring at the termini of stems in tRNA’s cloverleaf secondary structure affect the global three-dimensional conformation, produce unique recognition determinants for macromolecules to recognize tRNAs, and affect the accurate and efficient decoding ability of tRNAs. This review will discuss the impact of specific chemical moieties on the structure, stability, electrochemical properties, and function of tRNAs.

  10. Chemical functionalization of ceramic tile surfaces by silane coupling agents: polymer modified mortar adhesion mechanism implications

    Directory of Open Access Journals (Sweden)

    Alexandra Ancelmo Piscitelli Mansur

    2008-09-01

    Full Text Available Adhesion between tiles and mortars are crucial to the stability of ceramic tile systems. From the chemical point of view, weak forces such as van der Waals forces and hydrophilic interactions are expected to be developed preferably at the tiles and polymer modified Portland cement mortar interface. The main goal of this paper was to use organosilanes as primers to modify ceramic tile hydrophilic properties to improve adhesion between ceramic tiles and polymer modified mortars. Glass tile surfaces were treated with several silane derivatives bearing specific functionalities. Contact angle measurements and Fourier Transform Infrared Spectroscopy (FTIR were used for evaluating the chemical changes on the tile surface. In addition, pull-off tests were conducted to assess the effect on adhesion properties between tile and poly(ethylene-co-vinyl acetate, EVA, modified mortar. The bond strength results have clearly shown the improvement of adherence at the tile-polymer modified mortar interface, reflecting the overall balance of silane, cement and polymer interactions.

  11. Osteogenesis ability of biomimetic modified 3Y-TZP ceramic using chemical treatment

    Energy Technology Data Exchange (ETDEWEB)

    Hsu, Shih-Kuang [Department of Dental Technology and Materials Science, Central Taiwan University of Science and Technology, Taichung 40601, Taiwan, ROC (China); Chang, Pai-Ling [Taoyuan General Hospital, Taoyuan 33004, Taiwan, ROC (China); Ho, Wen-Fu [Department of Chemical and Materials Engineering, National University of Kaohsiung, Kaohsiung 81148, Taiwan, ROC (China); Hsu, Hsueh-Chuan; Liao, Huei-Jyuan [Department of Dental Technology and Materials Science, Central Taiwan University of Science and Technology, Taichung 40601, Taiwan, ROC (China); Wu, Shih-Ching, E-mail: scwu@ctust.edu.tw [Department of Dental Technology and Materials Science, Central Taiwan University of Science and Technology, Taichung 40601, Taiwan, ROC (China)

    2015-12-01

    In this study, RGD peptide derived from extracellular matrix proteins was employed to modify the surface of yttria-tetragonal zirconia polycrystal (3Y-TZP) to promote cell adhesion. The surface of 3Y-TZP ceramic specimens was first modified using chemical treatment with aqueous solutions of H{sub 3}PO{sub 4}, CH{sub 3}COOH, and NaOH, for the formation of Zr–OH surface functional groups. Then, the RGD peptide was immobilized on the surface of the 3Y-TZP through silanization method, with covalent bonding via the Zr–OH surface functional groups. From this study, the RGD peptide can successfully be grafted onto the chemical modified 3Y-TZP surface. The –OH functional groups formed on the surface of 3Y-TZP after acid/alkaline chemical treatment contribute to the grafting reaction of RGD peptides. The use of phosphoric acid solution in 3Y-TZP surface treatment before RGD peptide grafting for biomimetic modification can significantly enhance cell adhesion, proliferation, and differentiation. - Highlights: • This study successfully immobilized the peptides onto the surface of zirconia. • Acid/alkaline chemical treatment promotes the formation of − OH functional groups. • The use of phosphoric acid solution produced the formation of most − OH. • Peptides can significantly enhance cell adhesion, proliferation, and differentiation.

  12. Polynuclear Nickel Hexacyanoferrate/Graphitized Mesoporous Carbon Hybrid Chemically Modified Electrode for Selective Hydrazine Detection

    OpenAIRE

    Palani Barathi; Annamalai Senthil Kumar; Minnal Ranjan Babu Karthick

    2011-01-01

    A hybrid polynuclear nickel hexacyanoferrate (NiHCFe)/graphitized mesoporous carbon- (GMC-) modified glassy carbon electrode (GCE/NiHCFe@GMC) has been prepared by a sequential method using electrodeposited Ni on a GMC-modified glassy carbon electrode (GCE/Ni@GMC) as a template and [Fe(CN)6]3− as an in-situ chemical precipitant, without any additional interlinking agent. Physicochemical and electrochemical characterizations reveal the presence of NiHCFe units within the porous sites of the GM...

  13. A Switching Algorithm Based on Modified Quasi-Newton Equation

    Institute of Scientific and Technical Information of China (English)

    Yueting Yang; Chengxian Xu

    2006-01-01

    In this paper, a switching method for unconstrained minimization is proposed.The method is based on the modified BFGS method and the modified SR1 method. The eigenvalues and condition numbers of both the modified updates are evaluated and used in the switching rule. When the condition number of the modified SR1 update is superior to the modified BFGS update, the step in the proposed quasi-Newton method is the modified SR1 step. Otherwise the step is the modified BFGS step. The efficiency of the proposed method is tested by numerical experiments on small, medium and large scale optimization.The numerical results are reported and analyzed to show the superiority of the proposed method.

  14. Nanotube-Based Chemical and Biomolecular Sensors

    Institute of Scientific and Technical Information of China (English)

    J.Koh; B.Kim; S.Hong; H.Lim; H.C.Choi

    2008-01-01

    We present a brief review about recent results regarding carbon nanotube (CNT)-based chemical and biomolecular sensors. For the fabrication of CNT-based sensors, devices containing CNT channels between two metal electrodes are first fabricated usually via chemical vapor deposition (CVD) process or "surface programmed assembly" method. Then, the CNT surfaces are often functionalized to enhance the selectivity of the sensors. Using this process, highly-sensitive CNT-based sensors can be fabricated for the selective detection of various chemical and biological molecules such as hydrogen, ammonia, carbon monoxide, chlorine gas, DNA, glucose, alcohol, and proteins.

  15. Adhesion mapping of chemically modified and poly(ethylene oxide)-grafted glass surfaces

    OpenAIRE

    Jogikalmath, G.; Stuart, J.K.; Pungor, A.; Hlady, V.

    1999-01-01

    Two-dimensional mapping of the adhesion pull-off forces was used to study the origin of surface heterogeneity in the grafted poly(ethylene oxide) (PEO) layer. The variance of the pull-off forces measured over the μm-sized regions after each chemical step of modifying glass surfaces was taken to be a measure of the surface chemical heterogeneity. The attachment of γ-glycidoxypropyltrimethoxy silane (GPS) to glass decreased the pull-off forces relative to the clean glass and made the surface mo...

  16. Highly improved chromium (III uptake capacity in modified sugarcane bagasse using different chemical treatments

    Directory of Open Access Journals (Sweden)

    Vanessa Cristina Gonçalves Dos Santos

    2012-01-01

    Full Text Available The present paper focuses on improving chromium (III uptake capacity of sugarcane bagasse through its chemical modification with citric acid and/or sodium hydroxide. The chemical modifications were confirmed by infrared spectroscopy, with an evident peak observed at 1730 cm-1, attributed to carbonyl groups. Equilibrium was reached after 24 h, and the kinetics followed the pseudo-second-order model. The highest chromium (III maximum adsorption capacity (MAC value was found when using sugarcane bagasse modified with sodium hydroxide and citric acid (58.00 mg g-1 giving a MAC value about three times greater (20.34 mg g-1 than for raw sugarcane bagasse.

  17. Removal of lead from aqueous solution with native and chemically modified corncobs.

    Science.gov (United States)

    Tan, Guangqun; Yuan, Hongyan; Liu, Yong; Xiao, Dan

    2010-02-15

    In this study, corncobs biomass was utilized as an adsorbent to remove Pb(II) from aqueous solution. The adsorption behavior of Pb(II) was studied under different conditions, including solution pH, contact time and metal concentration. Ground corncobs were modified with CH(3)OH and NaOH to investigate the effect of chemical modification on Pb(II) binding capacity. Results showed that Pb(II) binding on the biomass is pH-dependent and the kinetics can be well described by the Lagergren-second-order model. The maximum Pb(II) binding capacity q(max) calculated from Langmuir isotherm was 0.0783 mmol/g. After base hydrolysis of the biomass, Pb(II) binding capacity increased from 0.0783 to 0.2095 mmol/g (about 43.4 mg Pb/g). However, Pb(II) binding capacity on the esterified corncobs decreased greatly from 0.0783 to 0.0381 mmol/g. Fourier transform infrared spectroscopy (FTIR) analysis showed that hydroxyl and carboxylic (COO(-)) groups on the biomass play an important role in Pb(II) binding process. The X-ray photoelectron spectroscopy (XPS) data further indicated that lead is adsorbed as Pb(2+) and is attached to oxide groups on the biomass.

  18. 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}.

  19. Chemically Modified Ordered Mesoporous Carbon/Polyaniline Composites for Electrochemical Capacitors

    Institute of Scientific and Technical Information of China (English)

    KONG Ling-bin; ZHANG Jing; CAI Jian-jun; YANG Zhen-sheng; LUO Yong-chun; KANG Long

    2011-01-01

    Chemically modified ordered mesoporous carbon CMK-3 materials were prepared by means of an easy wet-oxidative method in 2 mol/L nitric acid aqueous solution. A large amount of oxygen-containing functional groups were introduced onto the CMK-3 surface. Modified CMK-3(m-CMK-3) and aniline monomer were polymerized via an in situ chemical oxidative polymerization method. Morphological characterizations of m-CMK-3/PANI (polyaniline) composites were carried out via field emission scanning electron microscopy(SEM). Their electrochemical properties were investigated with cyclic voltammetry, galvanostatic charge-discharge, and electrochemical impedance spectroscopy. The m-CMK-3/PANI composites have excellent properties in capacitance, and the highest specific capacitance(SC) value was up to 489 F/g, suggesting their potential application in the electrode material for electrochemical capacitors.

  20. Applicability and Optimal Parameters Analysis for Chemical Phosphorus Removal in a Modified Carrousel Oxidation Ditch

    OpenAIRE

    Tao Zhang; Yonghong Zhao

    2017-01-01

    In order to confine the aqua-eutrophication problem arising from phosphorus pollution, many municipal wastewater treatment plants have to improve their executive drainage standard for total phosphorus (TP). In this study, a municipal wastewater treatment plant employing modified Carrousel oxidation ditch as main biological treatment unit was selected as a representative case. Technical necessity for adding a chemically enhanced phosphorus removal unit was analysed, and process feasibility was...

  1. Chemical modifiers in arsenic determination in biological materials by tungsten coil electrothermal atomic absorption spectrometry.

    Science.gov (United States)

    Bruhn, C G; Huerta, V N; Neira, J Y

    2004-01-01

    Palladium, iridium, and rhodium are evaluated as possible chemical modifiers in the determination of As in digest solutions of biological materials (human hair and clam) by tungsten coil electrothermal atomic absorption spectrophotometry (TCA-AAS). The modifier in solution was applied onto the coil and thermally pre-reduced; the pre-reduction conditions, the amount of modifier, and the thermal program were optimized. Palladium was not satisfactory, whereas Ir and Rh were effective modifiers and rendered better relative sensitivity for As by a factor of 1.4 and 1.9, respectively compared to the case without modifier. Upon optimization of thermal conditions for As in pre-reduced Ir (2.0 microg) and Rh (2.0 microg) modifiers and in the digest solutions of the study matrices, Rh (2.0 microg) was more effective modifier and was selected as such. The mean within-day repeatability was 2.8% in consecutive measurements (25-100 microg L(-1)) (3 cycles, each of n=6) and confirmed good short-term stability of the absorbance measurements. The mean reproducibility was 4.4% (n=20 in a 3-day period) and the detection limit (3 sigmablank/slope) was 29 pg (n=15). The useful coil lifetime in Rh modifier was extended to 300-400 firings. Validation was by determination of As in the certified reference material (CRM) of "Oyster tissue" solution with a percentage relative error (Erel%) of 2% and percentage relative standard deviation (RSD%) of 3% (n=4), and by analytical recovery of As spiked in CRM of human hair [94 +/- 8% (n=4)]. The methodology is simple, fast (sample readout frequency 21 h(-1)), reliable, of low cost, and was applied to the determination of As in hair samples of exposed and unexposed workers.

  2. Chemical modifiers in arsenic determination in biological materials by tungsten coil electrothermal atomic absorption spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Bruhn, C.G.; Huerta, V.N.; Neira, J.Y. [Departamento de Analisis Instrumental, Facultad de Farmacia, Universidad de Concepcion, P.O. Box 237, Concepcion (Chile)

    2004-01-01

    Palladium, iridium, and rhodium are evaluated as possible chemical modifiers in the determination of As in digest solutions of biological materials (human hair and clam) by tungsten coil electrothermal atomic absorption spectrophotometry (TCA-AAS). The modifier in solution was applied onto the coil and thermally pre-reduced; the pre-reduction conditions, the amount of modifier, and the thermal program were optimized. Palladium was not satisfactory, whereas Ir and Rh were effective modifiers and rendered better relative sensitivity for As by a factor of 1.4 and 1.9, respectively compared to the case without modifier. Upon optimization of thermal conditions for As in pre-reduced Ir (2.0 {mu}g) and Rh (2.0 {mu}g) modifiers and in the digest solutions of the study matrices, Rh (2.0 {mu}g) was more effective modifier and was selected as such. The mean within-day repeatability was 2.8% in consecutive measurements (25-100 {mu}g L{sup -1}) (3 cycles, each of n=6) and confirmed good short-term stability of the absorbance measurements. The mean reproducibility was 4.4% (n=20 in a 3-day period) and the detection limit (3{sigma}{sub blank}/slope) was 29 pg (n=15). The useful coil lifetime in Rh modifier was extended to 300-400 firings. Validation was by determination of As in the certified reference material (CRM) of ''Oyster tissue'' solution with a percentage relative error (E{sub rel}%) of 2% and percentage relative standard deviation (RSD%) of 3% (n=4), and by analytical recovery of As spiked in CRM of human hair [94{+-}8% (n=4)]. The methodology is simple, fast (sample readout frequency 21 h{sup -1}), reliable, of low cost, and was applied to the determination of As in hair samples of exposed and unexposed workers. (orig.)

  3. Ningxia Becomes China's Largest Coal Chemical Base

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    @@ Northwest China's Ningxia Hui Autonomous Region plans to invest more than 100 billion yuan (US$12.9 billion) to build Asia's largest liquefied-coal base,according to the regional development and reform commission. The first group of projects, designed to produce methanol and other chemicals from coal, are under construction in the Ningdong Chemical Resource Base, which is located near coal deposits containing 80 percent of Ningxia's known coal reserves, said Hao Linhai, director of the regional commission.

  4. Electrochemical impedance spectroscopy for graphene surface modification and protein translocation through the chemically modified graphene nanopore

    Science.gov (United States)

    Tiwari, Purushottam; Shan, Yuping; Wang, Xuewen; Darici, Yesim; He, Jin

    2014-03-01

    The multilayer graphene surface has been modified using mercaptohexadecanoic acid (MHA) and 1,2-dimyristoyl-sn-glycero-3-phosphoethanolamine-N-[methoxy(polyethylene glycol)-750] (DPPE-PEG750). The surface modifications are evaluated using electrochemical impedance spectroscopy (EIS). EIS measurements show the better graphene surface passivation with DPPE-PEG750 than with MHA. After modification with ferritin, the MHA modified surface shows greater charge transfer resistance (Rct) change than DPPE-PEG750 modified surface. Based on these results the translocations of ferritin through modified graphene nanopore with diameter 5-20 nm are studied. The translocation is more successful through DPPE-PEG750 modified graphene nanopore. This concludes that that the attachment of ferritin to DPPE-PEG750 modified graphene nanopore is not significant compared to MHA modified pore for the ferritin translocation hindrance. These results nicely correlate with the EIS data for respective Rct change of ferritin modified surfaces. P. Tiwari would like to thank FIU School of Integrated Science & Humanity, College Arts & Sciences for the research assistantship.

  5. Calorimetric and Spectroscopic Analysis of the Thermal Stability of Short Duplex DNA-Containing Sugar and Base-Modified Nucleotides.

    Science.gov (United States)

    Fakhfakh, Kareem; Hughesman, Curtis B; Louise Creagh, A; Kao, Vincent; Haynes, Charles

    2016-01-01

    Base- and sugar-modified analogs of DNA and RNA are finding ever expanding use in medicine and biotechnology as tools to better tailor structured oligonucleotides by altering their thermal stability, nuclease resistance, base-pairing specificity, antisense activity, or cellular uptake. Proper deployment of these chemical modifications generally requires knowledge of how each affects base-pairing properties and thermal stabilities. Here, we describe in detail how differential scanning calorimetry and UV spectroscopy may be used to quantify the melting thermodynamics of short dsDNA containing chemically modified nucleosides in one or both strands. Insights are provided into why and how the presence of highly stable base pairs containing modified nucleosides can alter the nature of calorimetry or melting spectroscopy data, and how each experiment must therefore be conducted to ensure high-quality melting thermodynamics data are obtained. Strengths and weaknesses of the two methods when applied to chemically modified duplexes are also addressed.

  6. Deposition of carbon nanotubes onto aramid fibers using as-received and chemically modified fibers

    Science.gov (United States)

    Rodríguez-Uicab, O.; Avilés, F.; Gonzalez-Chi, P. I.; Canché-Escamilla, G.; Duarte-Aranda, S.; Yazdani-Pedram, M.; Toro, P.; Gamboa, F.; Mazo, M. A.; Nistal, A.; Rubio, J.

    2016-11-01

    Multiwall carbon nanotubes (MWCNTs) oxidized by an acid treatment were deposited on the surface of as-received commercial aramid fibers containing a surface coating ("sizing"), and fibers modified by either a chlorosulfonic treatment or a mixture of nitric and sulfuric acids. The surface of the aramid fiber activated by the chemical treatments presents increasing density of CO, COOH and OH functional groups. However, these chemical treatments reduced the tensile mechanical properties of the fibers, especially when the nitric and sulfuric acid mixture was used. Characterization of the MWCNTs deposited on the fiber surface was conducted by scanning electron microscopy, Raman spectroscopy mapping and X-ray photoelectron spectroscopy. These characterizations showed higher areal concentration and more homogeneous distribution of MWCNTs over the aramid fibers for as-received fibers and for those modified with chlorosulfonic acid, suggesting the existence of interaction between the oxidized MWCNTs and the fiber coating. The electrical resistance of the MWCNT-modified aramid yarns comprising ∼1000 individual fibers was in the order of MΩ/cm, which renders multifunctional properties.

  7. A new modified-rate approach for gas-grain chemical simulations

    CERN Document Server

    Garrod, R T

    2008-01-01

    Understanding grain-surface processes is crucial to interpreting the chemistry of the ISM. However, accurate surface chemistry models are computationally expensive and are difficult to integrate with gas-phase simulations. A new modified-rate method for solving grain-surface chemical systems is presented. Its purpose is accurately to model highly complex systems that can otherwise only be treated using the sometimes inadequate rate-equation approach. In contrast to previous rate-modification techniques, the functional form of the surface production rates was modified, and not simply the rate coefficient. This form is appropriate to the extreme "small-grain" limit, and can be verified using an analytical master-equation approach. Various further modifications were made to this basic form, to account for competition between processes, to improve estimates of surface occupation probabilities, and to allow a switch-over to the normal rate equations where these are applicable. The new method was tested against sys...

  8. Silencing of Inducible Immunoproteasome Subunit Expression by Chemically Modified siRNA and shRNA.

    Science.gov (United States)

    Gvozdeva, Olga V; Prassolov, Vladimir S; Zenkova, Marina A; Vlassov, Valentin V; Chernolovskaya, Elena L

    2016-08-01

    Overexpression of inducible subunits of immunoproteasome is related to pathogenesis of some chronic diseases. Specific inhibition of the immunosubunits may be used for the treatment of these diseases and RNA interference is one of the potent methods used in this area. We designed 2'-O-methyl modified siRNAs with selectively protected nuclease-sensitive sites, which efficiently silence LMP2, LMP7, and MECL-1 genes expression. To provide stable long-lasting inhibition of target genes, short-hairpin RNAs (shRNA) expressed by lentiviral vectors were constructed. Our results demonstrated that chemically modified siRNAs inhibited the expression of target genes with similar efficiency or with efficiency exceeding that of corresponding shRNAs and provide silencing effect for 5 days.

  9. Retention of proteins and metalloproteins in open tubular capillary electrochromatography with etched chemically modified columns.

    Science.gov (United States)

    Pesek, Joseph J; Matyska, Maria T; Salgotra, Vasudha

    2008-09-01

    Etched chemically modified capillaries with two different bonded groups (pentyl and octadecyl) are compared for their migration behavior of several common proteins and metalloproteins as well as metalloproteinases. Migration times, efficiency and peak shape are evaluated over the pH range of 2.1-8.1 to determine any effects of the bonded group on the electrochromatographic behavior of these compounds. One goal was to determine if the relative hydrophobicity of the stationary phase has a significant effect on proteins in the open tubular format of capillary electrochromatography as it does in HPLC. Reproducibility of the migration times is also investigated.

  10. Retention of Proteins and Metalloproteins in Open Tubular Capillary Electrochromatography with Etched Chemically Modified Columns

    Science.gov (United States)

    Pesek, Joseph J.; Matyska, Maria T.; Salgotra, Vasudha

    2010-01-01

    Etched chemically modified capillaries with two different bonded groups (pentyl and octadecyl) are compared for their migration behavior of several common proteins and metalloproteins as well as metalloproteinases. Migration times, efficiency and peak shape are evaluated over the pH range of 2.1 to 8.1 to determine any effects of the bonded group on the electrochromatographic behavior of these compounds. One goal was to determine if the relative hydrophobicity of the stationary phase has a significant effect on proteins in the open tubular format of capillary electrochromatography as it does in HPLC. Reproducibility of the migration times is also investigated. PMID:18850653

  11. Modified Augmented Lagrange Multiplier Methods for Large-Scale Chemical Process Optimization

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Chemical process optimization can be described as large-scale nonlinear constrained minimization. The modified augmented Lagrange multiplier methods (MALMM) for large-scale nonlinear constrained minimization are studied in this paper. The Lagrange function contains the penalty terms on equality and inequality constraints and the methods can be applied to solve a series of bound constrained sub-problems instead of a series of unconstrained sub-problems. The steps of the methods are examined in full detail. Numerical experiments are made for a variety of problems, from small to very large-scale, which show the stability and effectiveness of the methods in large-scale problems.

  12. Size-dependent mobility of gold nano-clusters during growth on chemically modified graphene

    Energy Technology Data Exchange (ETDEWEB)

    Bell, Gavin R., E-mail: gavin.bell@warwick.ac.uk; Dawson, Peter M.; Pandey, Priyanka A.; Wilson, Neil R. [Department of Physics, University of Warwick, Coventry CV4 7AL (United Kingdom); Mulheran, Paul A. [Department of Chemical and Process Engineering, University of Strathclyde, James Weir Building, 75 Montrose St., Glasgow G1 1XJ (United Kingdom)

    2014-01-01

    Gold nano-clusters were grown on chemically modified graphene by direct sputter deposition. Transmission electron microscopy of the nano-clusters on these electron-transparent substrates reveals an unusual bimodal island size distribution (ISD). A kinetic Monte Carlo model of growth incorporating a size-dependent cluster mobility rule uniquely reproduces the bimodal ISD, providing strong evidence for the mobility of large clusters during surface growth. The cluster mobility exponent of −5/3 is consistent with cluster motion via one-dimensional diffusion of gold atoms around the edges of the nano-clusters.

  13. Size-dependent mobility of gold nano-clusters during growth on chemically modified graphene

    Directory of Open Access Journals (Sweden)

    Gavin R. Bell

    2014-01-01

    Full Text Available Gold nano-clusters were grown on chemically modified graphene by direct sputter deposition. Transmission electron microscopy of the nano-clusters on these electron-transparent substrates reveals an unusual bimodal island size distribution (ISD. A kinetic Monte Carlo model of growth incorporating a size-dependent cluster mobility rule uniquely reproduces the bimodal ISD, providing strong evidence for the mobility of large clusters during surface growth. The cluster mobility exponent of −5/3 is consistent with cluster motion via one-dimensional diffusion of gold atoms around the edges of the nano-clusters.

  14. An atlas of RNA base pairs involving modified nucleobases with optimal geometries and accurate energies

    KAUST Repository

    Chawla, Mohit

    2015-06-27

    Posttranscriptional modifications greatly enhance the chemical information of RNA molecules, contributing to explain the diversity of their structures and functions. A significant fraction of RNA experimental structures available to date present modified nucleobases, with half of them being involved in H-bonding interactions with other bases, i.e. ‘modified base pairs’. Herein we present a systematic investigation of modified base pairs, in the context of experimental RNA structures. To this end, we first compiled an atlas of experimentally observed modified base pairs, for which we recorded occurrences and structural context. Then, for each base pair, we selected a representative for subsequent quantum mechanics calculations, to find out its optimal geometry and interaction energy. Our structural analyses show that most of the modified base pairs are non Watson–Crick like and are involved in RNA tertiary structure motifs. In addition, quantum mechanics calculations quantify and provide a rationale for the impact of the different modifications on the geometry and stability of the base pairs they participate in.

  15. Peroxide-modified titanium dioxide: a chemical analog of putative Martian soil oxidants

    Science.gov (United States)

    Quinn, R. C.; Zent, A. P.

    1999-01-01

    Hydrogen peroxide chemisorbed on titanium dioxide (peroxide-modified titanium dioxide) is investigated as a chemical analog to the putative soil oxidants responsible for the chemical reactivity seen in the Viking biology experiments. When peroxide-modified titanium dioxide (anatase) was exposed to a solution similar to the Viking labeled release (LR) experiment organic medium, CO2 gas was released into the sample cell headspace. Storage of these samples at 10 degrees C for 48 hr prior to exposure to organics resulted in a positive response while storage for 7 days did not. In the Viking LR experiment, storage of the Martian surface samples for 2 sols (approximately 49 hr) resulted in a positive response while storage for 141 sols essentially eliminated the initial rapid release of CO2. Heating the peroxide-modified titanium dioxide to 50 degrees C prior to exposure to organics resulted in a negative response. This is similar to, but not identical to, the Viking samples where heating to approximately 46 degrees C diminished the response by 54-80% and heating to 51.5 apparently eliminated the response. When exposed to water vapor, the peroxide-modified titanium dioxide samples release O2 in a manner similar to the release seen in the Viking gas exchange experiment (GEx). Reactivity is retained upon heating at 50 degrees C for three hours, distinguishing this active agent from the one responsible for the release of CO2 from aqueous organics. The release of CO2 by the peroxide-modified titanium dioxide is attributed to the decomposition of organics by outer-sphere peroxide complexes associated with surface hydroxyl groups, while the release of O2 upon humidification is attributed to more stable inner-sphere peroxide complexes associated with Ti4+ cations. Heating the peroxide-modified titanium dioxide to 145 degrees C inhibited the release of O2, while in the Viking experiments heating to this temperature diminished but did not eliminated the response. Although the

  16. A Mechanistic Study of Chemically Modified Inorganic Membranes for Gas and Liquid Separations

    Energy Technology Data Exchange (ETDEWEB)

    Way, J Douglas

    2011-01-21

    This final report will summarize the progress made during the period August 1, 1993 - October 31, 2010 with support from DOE grant number DE-FG03-93ER14363. The objectives of the research have been to investigate the transport mechanisms in micro- and mesoporous, metal oxide membranes and to examine the relationship between the microstructure of the membrane, the membrane surface chemistry, and the separation performance of the membrane. Examples of the membrane materials under investigation are the microporous silica hollow fiber membrane manufactured by PPG Industries, chemically modified mesoporous oxide membranes, and polymer membranes containing microporous oxides (mixed matrix membranes). Analytical techniques such as NMR, FTIR and Raman spectroscopy, thermal analysis, and gas adsorption were used to investigate membrane microstructure and to probe the chemical interactions occurring at the gas-membrane interface.

  17. Free-radical-promoted conversion of graphite oxide into chemically modified graphene.

    Science.gov (United States)

    Chai, Na-Na; Zeng, Jing; Zhou, Kai-Ge; Xie, Yu-Long; Wang, Hang-Xing; Zhang, Hao-Li; Xu, Chen; Zhu, Ji-Xin; Yan, Qing-Yu

    2013-05-01

    The preparation of chemically modified graphene (CMG) generally involves the reduction of graphite oxide (GO) by using various reducing reagents. Herein, we report a free-radical-promoted synthesis of CMG, which does not require any conventional reductant. We demonstrated that the phenyl free radical can efficiently promote the conversion of GO into CMG under mild conditions and produces phenyl-functionalized CMG. This pseudo-"reduction" process is attributed to a free-radical-mediated elimination of the surface-attached oxygen-containing functionalities. This work illustrates a new strategy for preparing CMG that is alternative to the conventional means of chemical reduction. Furthermore, the phenyl-functionalized graphene shows an excellent performance as an electrode material for lithium-battery applications.

  18. DIMENSIONAL STABILITY AND WATER REPELLENT EFFICIENCY MEASUREMENT OF CHEMICALLY MODIFIED TROPICAL LIGHT HARDWOOD

    Directory of Open Access Journals (Sweden)

    Md Saiful Islam,

    2012-01-01

    Full Text Available Chemical modification is an often-followed route to improve physical and mechanical properties of solid wood materials. In this study five kinds of tropical light hardwoods species, namely jelutong (Dyera costulata, terbulan (Endospermum diadenum, batai (Paraserianthes moluccana, rubberwood (Hevea brasiliensis, and pulai (Alstonia pneumatophora, were chemically modified with benzene diazonium salt to improve their dimensional stability and water repellent efficiency. The dimensional stability of treated samples in terms of volumetric swelling coefficient (S and anti-swelling-efficiency (ASE were found to improve with treatment. The water repellent efficiency (WRE values also seemed to improve considerably with treatment of wood samples. Furthermore, treated wood samples had lower water and moisture absorption compared to that of untreated ones.

  19. Chemical and rheological evaluation of ageing properties of SBS polymer modified bitumens

    Energy Technology Data Exchange (ETDEWEB)

    Lu, X.; Isacsson, U. [Royal Institute of Technology, Stockholm (Sweden). Division of Highway Engineering

    1998-07-01

    The ageing properties of Styrene-Butadiene-Styrene (SBS) polymer modified bitumens were evaluated using Dynamic Mechanical Analysis (DMA), Gel Permeation Chromatography (GPC) and Fourier Transform InfraRed (FTIR) spectroscopy. The binders were aged by means of the Thin Film Oven Test (TFOT) and the Rolling Thin Film Oven Test (RTFOT), respectively. It was observed that ageing resulted in degradation of the SBS polymer containing molecules and increase in bitumen molecular weight. The polymer was observed to resist formation of sulphoxides. Changes in the rheological properties of aged-modified binders were dependent on a combined effect of bitumen oxidation and polymer degradation, which varied with bitumen source/grade and polymer type/content. In all cases, the aged modified binders showed better rheological properties than aged base bitumens. The study also indicated that the ageing index obtained using DMA was largely influenced by temperature and frequency. This parameter may be applied for evaluating the base bitumens and modified binders with a low polymer content (3% in this study), but not for modified binders with a high (6%) polymer content. 18 refs., 9 figs., 4 tabs.

  20. A Modified Approach for Calculating Dressed Quark Propagator at Finite Chemical Potential

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    Based on the rainbow approximation of Dyson-Schwinger equation and the assumption that the full inverse quark propagator at finite chemical potential is analytic in the neighborhood of μ = 0, it is proved that the dressed From the dressed quark propagator at finite chemical potential μ can be written as (g0-1)[μ]=iγ·(p~)A((p~2))+B((p~2))with (p~)μ=((p),p4+iμ).From the dressed quark propagator at finite chemical potential in Munczek model the bag constant of a baryon and the scalar quark condensate are evaluated. A comparison with previous results is given.

  1. Bio-based targeted chemical engineering education

    NARCIS (Netherlands)

    N.M. Márquez Luzardoa; Dr. ir. Jan Venselaar

    2012-01-01

    Avans University of Applied Sciences is redrafting its courses and curricula in view of sustainability. For chemical engineering in particular that implies a focus on 'green' and bio-based processes, products and energy. Avans is situated in the Southwest region of the Netherlands and specifically

  2. HIGHLY EFFECTIVE CHEMICAL MODIFIERS FOR PRODUCTION OF CONCRETES WITH PRE-SET PROPERTIES

    Directory of Open Access Journals (Sweden)

    Tkach Evgeniya Vladimirovna

    2012-10-01

    Full Text Available The paper demonstrates the application of industrial by-products and recycled materials. Waterproofing admixtures improve the structure and the properties of the cement stone. Development and preparation of highly effective waterproofing modifiers of durable effect, as well as development of the process procedure parameters, including mixing, activation, heat treatment, etc. are to be implemented. The composition of waterproofing modifiers is to be fine-tuned to synergize the behaviour of various ingredients of cement systems to assure the substantial improvement of their strength, freeze- and corrosion resistance. Multi-functional waterproofing admixtures were used to produce highly effective modified concretes. The key idea of the new method of modifying cement-based building materials is that the waterproofing admixture concentration is to exceed 10% of the weight of the binding agent within the per-unit weight of the cement stone, given that its strength does not deteriorate. GKM-type modifier coupled with organo-mineral waterproofing admixture concentration agent GT-M may be recommended for mass use in the manufacturing of hydraulic concrete and reinforced concrete products. Overview of their practical implementation has proven that waterproofing modifier GKM-S, if coupled with waterproofing admixture concentration agent GT-M, improves the corrosion control inside the cement stone and makes it possible to manufacture durable concrete and reinforced concrete products that demonstrate pre-set physical and processing behaviour. Comprehensive concrete modification by modifier GKM-S and waterproofing admixture concentration agent GT-M may be regarded as one of the most ambitious methods of production of highly effective waterproof concretes.

  3. Microstructural and Chemical Rejuvenation of a Ni-Based Superalloy

    Science.gov (United States)

    Yao, Zhiqi; Degnan, Craig C.; Jepson, Mark A. E.; Thomson, Rachel C.

    2016-10-01

    The microstructural evolution of the Ni-based superalloy CMSX-4 including the change in gamma prime morphology, size, and distribution after high-temperature degradation and subsequent rejuvenation heat treatments has been examined using field emission gun scanning electron microscopy and transmission electron microscopy. In this paper, it is shown that there are significant differences in the size of the `channels' between gamma prime particles, the degree of rafting, and the size of tertiary gamma prime particles in each of the different microstructural conditions studied. Chemical analysis has been carried out to compare rejuvenated and pre-service samples after the same subsequent degradation procedure. The results indicate that although the microstructures of pre-service and rejuvenated samples are similar, chemical differences are more pronounced in the rejuvenated samples, suggesting that chemical segregation from partitioning of the elements was not completely eliminated through the applied rejuvenation heat treatment. A number of modified rejuvenation heat treatment trials were carried out to reduce the chemical segregation prior to creep testing. The creep test results suggest that chemical segregation has an immeasurable influence on the short-term mechanical properties under the test conditions used here, indicating that further work is required to fully understand the suitability of specific rejuvenation heat treatments and their role in the extension of component life in power plant applications.

  4. Microstructural and Chemical Rejuvenation of a Ni-Based Superalloy

    Science.gov (United States)

    Yao, Zhiqi; Degnan, Craig C.; Jepson, Mark A. E.; Thomson, Rachel C.

    2016-12-01

    The microstructural evolution of the Ni-based superalloy CMSX-4 including the change in gamma prime morphology, size, and distribution after high-temperature degradation and subsequent rejuvenation heat treatments has been examined using field emission gun scanning electron microscopy and transmission electron microscopy. In this paper, it is shown that there are significant differences in the size of the `channels' between gamma prime particles, the degree of rafting, and the size of tertiary gamma prime particles in each of the different microstructural conditions studied. Chemical analysis has been carried out to compare rejuvenated and pre-service samples after the same subsequent degradation procedure. The results indicate that although the microstructures of pre-service and rejuvenated samples are similar, chemical differences are more pronounced in the rejuvenated samples, suggesting that chemical segregation from partitioning of the elements was not completely eliminated through the applied rejuvenation heat treatment. A number of modified rejuvenation heat treatment trials were carried out to reduce the chemical segregation prior to creep testing. The creep test results suggest that chemical segregation has an immeasurable influence on the short-term mechanical properties under the test conditions used here, indicating that further work is required to fully understand the suitability of specific rejuvenation heat treatments and their role in the extension of component life in power plant applications.

  5. Aqueous dispersions of few-layer-thick chemically modified magnesium diboride nanosheets by ultrasonication assisted exfoliation

    Science.gov (United States)

    Das, Saroj Kumar; Bedar, Amita; Kannan, Aadithya; Jasuja, Kabeer

    2015-01-01

    The discovery of graphene has led to a rising interest in seeking quasi two-dimensional allotropes of several elements and inorganic compounds. Boron, carbon’s neighbour in the periodic table, presents a curious case in its ability to be structured as graphene. Although it cannot independently constitute a honeycomb planar structure, it forms a graphenic arrangement in association with electron-donor elements. This is exemplified in magnesium diboride (MgB2): an inorganic layered compound comprising boron honeycomb planes alternated by Mg atoms. Till date, MgB2 has been primarily researched for its superconducting properties; it hasn’t been explored for the possibility of its exfoliation. Here we show that ultrasonication of MgB2 in water results in its exfoliation to yield few-layer-thick Mg-deficient hydroxyl-functionalized nanosheets. The hydroxyl groups enable an electrostatically stabilized aqueous dispersion and create a heterogeneity leading to an excitation wavelength dependent photoluminescence. These chemically modified MgB2 nanosheets exhibit an extremely small absorption coefficient of 2.9 ml mg−1 cm−1 compared to graphene and its analogs. This ability to exfoliate MgB2 to yield nanosheets with a chemically modified lattice and properties distinct from the parent material presents a fundamentally new perspective to the science of MgB2 and forms a first foundational step towards exfoliating metal borides. PMID:26041686

  6. Adhesion mapping of chemically modified and poly(ethylene oxide)-grafted glass surfaces

    Science.gov (United States)

    Jogikalmath, G.; Stuart, J.K.; Pungor, A.; Hlady, V.

    2012-01-01

    Two-dimensional mapping of the adhesion pull-off forces was used to study the origin of surface heterogeneity in the grafted poly(ethylene oxide) (PEO) layer. The variance of the pull-off forces measured over the μm-sized regions after each chemical step of modifying glass surfaces was taken to be a measure of the surface chemical heterogeneity. The attachment of γ-glycidoxypropyltrimethoxy silane (GPS) to glass decreased the pull-off forces relative to the clean glass and made the surface more uniform. The subsequent hydrolysis of the terminal epoxide groups resulted in a larger surface heterogeneity which was modeled by two populations of the terminal hydroxyl groups, each with its own distribution of adhesion forces and force variance. The activation of the hydroxyls with carbonyldiimmidazole (CDI) healed the surface and lowered its adhesion, however, the force variance remained rather large. Finally, the grafting of the α,ω-diamino poly(ethyleneoxide) chains to the CDI-activated glass largely eliminated adhesion except at a few discrete regions. The adhesion on the PEO grafted layer followed the Poisson distribution of the pull-off forces. With the exception of the glass surface, a correlation between the water contact angles and the mean pull-off forces measured with the Si3N4 tip surfaces was found for all modified glass surfaces. PMID:22267896

  7. Determination of bisphenol A in food-simulating liquids using LCED with a chemically modified electrode.

    Science.gov (United States)

    D'Antuono, A; Dall'Orto, V C; Lo Balbo, A; Sobral, S; Rezzano, I

    2001-03-01

    Liquid chromatography with electrochemical detector (LC-ED), using a chemically modified electrode coated with a metalloporphyrin film, is reported for determination of bisphenol A (BPA) migration from polycarbonate baby bottles. The extraction process of the samples was performed according to regulations of the Southern Common Market (MERCOSUR), where certain food-simulating liquids [(A) distilled water, (B) acetic acid 3% V/V in distilled water, and (C) ethanol 15% V/V in distilled water] are defined along with controlled time and temperature conditions. The baseline obtained using the naked electrode showed a considerable drift which increased the detection limit. This effect was suppressed with the chemically modified electrode. A linear range up to 450 ppb along with a detection limit of 20 ppb for the amperometric detection technique was observed. The procedure described herein allowed lowering the detection limit of the method to 0.2 ppb. The value found for BPA in the food-simulating liquid is 1.2 ppb, which is below the tolerance limit for specific migration (4.8 ppm).

  8. Multiresolution edge detection based on modified bubble function and SWT

    Institute of Scientific and Technical Information of China (English)

    YU Rui-xing; LI Yan-jun; ZHANG Ke

    2006-01-01

    A new way based on a modified bubble function and stationary wavelet transform(SWT) is proposed to solve the problem that the conventional edge detection algorithms are sensitive to the noises.Firstly,the traditional bubble function is modified in order to get different time-frequency domain responses and to get filtering effects through adjusting the parameters. Secondly, the modified bubble function is combined with SWT to construct a multiresolution network. By using the modified bubble function to enhance the edges and by using SWT to reduce the noises, the edges can be extracted accurately,effectively and quickly with lower noise.Finally, the experimental results of the proposed edge detection algorithm are verified to be better than that with the traditional bubble function.

  9. Enhancing adsorption capacity of toxic malachite green dye through chemically modified breadnut peel: equilibrium, thermodynamics, kinetics and regeneration studies.

    Science.gov (United States)

    Chieng, Hei Ing; Lim, Linda B L; Priyantha, Namal

    2015-01-01

    Breadnut skin, in both its unmodified (KS) and base-modified (BM-KS) forms, was investigated for its potential use as a low-cost adsorbent for the removal of toxic dye, malachite green (MG). Characterization of the adsorbents was carried out using scanning electron microscope, X-ray fluorescence and Fourier transform infra-red spectroscopy. Batch adsorption experiments, carried out under optimized conditions, for the adsorption of MG were fitted using five isotherm models (Langmuir, Freundlich, Dubinin-Radushkevich, Temkin and Sips) and six error functions to determine the best-fit model. The adsorption capacity was greatly enhanced when breadnut skin was chemically modified with NaOH, leading to an adsorption capacity of 353.0 mg g(-1), that was far superior to most reported adsorbents for the removal of MG. Thermodynamics studies indicated that the adsorption of MG was spontaneous on KS and BM-KS, and the reactions were endothermic and exothermic, respectively. Kinetics studies showed that both followed the pseudo-second order. Regeneration experiments on BM-KS indicated that its adsorption capacity was still maintained at>90% even after five cycles. It can be concluded that NaOH-modified breadfruit skin has great potential to be utilized in real-life application as a low-cost adsorbent for the removal of MG in wastewater treatment.

  10. In vitro evolution of chemically-modified nucleic acid aptamers: Pros and cons, and comprehensive selection strategies.

    Science.gov (United States)

    Lipi, Farhana; Chen, Suxiang; Chakravarthy, Madhuri; Rakesh, Shilpa; Veedu, Rakesh N

    2016-12-01

    Nucleic acid aptamers are single-stranded DNA or RNA oligonucleotide sequences that bind to a specific target molecule with high affinity and specificity through their ability to adopt 3-dimensional structure in solution. Aptamers have huge potential as targeted therapeutics, diagnostics, delivery agents and as biosensors. However, aptamers composed of natural nucleotide monomers are quickly degraded in vivo and show poor pharmacodynamic properties. To overcome this, chemically-modified nucleic acid aptamers are developed by incorporating modified nucleotides after or during the selection process by Systematic Evolution of Ligands by EXponential enrichment (SELEX). This review will discuss the development of chemically-modified aptamers and provide the pros and cons, and new insights on in vitro aptamer selection strategies by using chemically-modified nucleic acid libraries.

  11. Elaboration and Properties of Nanocomposite Structures Based on Crown Modified Platinum Nanoparticles

    Institute of Scientific and Technical Information of China (English)

    H.Perez; S.Cavaliere-jaricot; P-A.Albouy; A.Etcheberry

    2007-01-01

    1 Results This paper presents the development of platinum nanocomposites structures based on organically modified c.a.2 nm core platinum nanoparticles.The chemical modification of the 4-mercaptoaniline functionalized particles by various in coming molecules is evidenced and precisely quantified.The particles can be dissolved like molecules in various solvents depending on the features of the new crown and X-rays shows that the interparticle distance is affected by the crown modification.These platinum n...

  12. The performance of chemically and physically modified local kaolinite in methanol dehydration to dimethyl ether

    Directory of Open Access Journals (Sweden)

    Sanaa M. Solyman

    2014-09-01

    Full Text Available The catalytic activity of modified natural kaolinite as a solid acid catalyst for dimethyl ether (DME preparation was investigated by following up the conversion% of methanol and the yield% of DME. Natural kaolinite (KN was treated chemically with H2O2 (KT followed by thermal treatment at 500 °C (KC and then mechano-chemically by ball milling with and without CaSO4 (KB-Ca and KB, respectively. These samples were characterized by XRD, FTIR, SEM, HRTEM, TGA and NH3-TPD techniques. The different techniques showed that the chemical treatment of kaolinite with H2O2 resulted in partial exfoliation/delamination of kaolinite, decreased the amount of acidic sites which is accompanied by increasing their strength. Calcination only decreased the acidic strength and slightly enlarged the particle size mostly due to heat effect. Ball milling resulted in multitude randomly-oriented crystals and increased the amount of acidic sites with the same strength of KT sample. CaSO4 mostly produced ordered monocrystalline kaolinite and created new acidic sites with slightly lower strength relative to KB. The catalytic activity and selectivity depend on the reaction temperature, the space velocity and the strength of acid sites. The most active sample is KB-Ca, which gives 84% DME due to its high amount and strength of acidic sites. The different modification methods resulted in 100% selectivity for DME.

  13. Physico-Chemical Properties and Biodegradability of Genetically Modified Populus trichocarpa and Pinus taeda

    Science.gov (United States)

    Edmunds, Charles Warren

    Increasing concerns over greenhouse gas emissions and the finite supply of fossil fuels lead to the goal of utilizing lignocellulosic feedstocks for biofuels, platform chemicals, and biocomposites. Lignin is responsible for the recalcitrance of lignocellulosic biomass and is a major barrier to its deconstruction. Great progress has been made in mapping and modifying the lignin biosynthetic pathway. However, the link between the genetic modification, resulting chemical and physical properties of the wood, and how these properties influence the thermomechanical and recalcitrance to biological and chemical degradation needs further investigation. In this dissertation, the study of modified Populus trichocarpa and Pinus taeda were utilized to accomplish this goal. Thermo-mechanical properties of genetically modified P. trichocarpa with altered lignin content and/or lignin structure were measured with a series of tools including; dynamic mechanical analysis, nuclear magnetic resonance, and wet chemistry techniques. Results demonstrated lignin content and lignin structure likely influence the glass transition temperature (Tg), and that decreased lignin content and the corresponding higher proportion of cell wall carbohydrates may contribute to increased molecular mobility in the wood polymer structure. The effect of lignin biosynthetic pathway modification on biological degradation of these transgenic wood specimens was of interest. However, experimental methods for fungal treatment on small young greenhouse-grown wood specimens are not well established. Therefore, a project was undertaken to develop a method for fungal inoculation and incubation for these unique specimens. Several parameters were tested, and a fungal treatment method was identified with sufficient weight loss after decay and significant reduction in variation of weight loss between replicates compared to previous experiments by direct inoculation of wood with liquid malt extract fungal culture

  14. Tannic Acid as a Bio-Based Modifier of Epoxy/Anhydride Thermosets

    Directory of Open Access Journals (Sweden)

    Xiaoma Fei

    2016-08-01

    Full Text Available Toughening an epoxy resin by bio-based modifiers without trade-offs in its modulus, mechanical strength, and other properties is still a big challenge. This paper presents an approach to modify epoxy resin with tannic acid (TA as a bio-based feedstock. Carboxylic acid-modified tannic acid (TA–COOH was first prepared through a simple esterification between TA and methylhexahydrophthalic anhydride, and then used as a modifier for the epoxy/anhydride curing system. Owing to the chemical modification, TA–COOH could easily disperse in epoxy resin and showed adequate interface interaction between TA–COOH and epoxy matrix, in avoid of phase separation. The use of TA–COOH in different proportions as modifier of epoxy/anhydride thermosets was studied. The results showed that TA–COOH could significantly improve the toughness with a great increase in impact strength under a low loading amount. Moreover, the addition of TA–COOH also simultaneously improved the tensile strength, elongation at break and glass transition temperature. The toughening and reinforcing mechanism was studied by scanning electron microscopy (SEM, dynamic mechanical analysis (DMA and thermal mechanical analysis (TMA, which should be owned to the synergistic effect of good interface interaction, aromatic structure, decreasing of cross linking density and increasing of free volume. This approach allows us to utilize the renewable tannic acid as an effective modifier for epoxy resin with good mechanical and thermal properties.

  15. A rule-based expert system for chemical prioritization using effects-based chemical categories.

    Science.gov (United States)

    Schmieder, P K; Kolanczyk, R C; Hornung, M W; Tapper, M A; Denny, J S; Sheedy, B R; Aladjov, H

    2014-01-01

    A rule-based expert system (ES) was developed to predict chemical binding to the estrogen receptor (ER) patterned on the research approaches championed by Gilman Veith to whom this article and journal issue are dedicated. The ERES was built to be mechanistically transparent and meet the needs of a specific application, i.e. predict for all chemicals within two well-defined inventories (industrial chemicals used as pesticide inerts and antimicrobial pesticides). These chemicals all lack structural features associated with high affinity binders and thus any binding should be low affinity. Similar to the high-quality fathead minnow database upon which Veith QSARs were built, the ERES was derived from what has been termed gold standard data, systematically collected in assays optimized to detect even low affinity binding and maximizing confidence in the negatives determinations. The resultant logic-based decision tree ERES, determined to be a robust model, contains seven major nodes with multiple effects-based chemicals categories within each. Predicted results are presented in the context of empirical data within local chemical structural groups facilitating informed decision-making. Even using optimized detection assays, the ERES applied to two inventories of >600 chemicals resulted in only ~5% of the chemicals predicted to bind ER.

  16. Sulfur Fixation by Chemically Modified Red Mud Samples Containing Inorganic Additives: A Parametric Study

    Directory of Open Access Journals (Sweden)

    Yang Liu

    2016-01-01

    Full Text Available Sulfur retention ability of Bayer red mud from alumina plant was investigated. Bayer red mud modified by fusel salt and waste mother liquor of sodium ferrocyanide as the main sulfur fixation agent and the calcium based natural mineral materials as servicing additives; the experimental results showed the following: (1 Through 10 wt% waste mother liquor of sodium ferrocyanide modifying Bayer red mud, sulfur fixation rate can increase by 13 wt%. (2 Magnesium oxide can obviously improve the sulfur fixation performance of Bayer red mud and up to a maximum sulfur fixation rate of 47 wt% at adding 1 wt% magnesium oxide. (3 Dolomite enhanced the sulfur fixation performances with the sulfur fixation rate of 68 wt% in optimized condition. (4 Vermiculite dust reduced sulfur dioxide during the fixed-sulfur process of modified Bayer red mud, and the desulphurization ration could reach up to a maximum 76 wt% at 950°C. (5 An advanced three-component sulfur fixation agent was investigated, in which the optimized mass ratio of modified Bayer red mud, dolomite, and vermiculite dust was 70 : 28 : 2 in order, and its sulfur fixation efficiency has reached to a maximum 87 wt% under its 20 wt% dosage in the coal.

  17. Chemically modified and nanostructured porous silicon as a drug delivery material and device

    Science.gov (United States)

    Anglin, Emily Jessica

    This thesis describes the fabrication, chemical modification, drug release, and toxicity studies of nanostructured porous silicon for the purposes of developing a smart drug delivery device. The first chapter is an introductory chapter, presenting the chemical and physical properties of porous silicon, the concepts and issues of current drug delivery devices and materials, and how porous silicon can address the issues regarding localized and controlled drug therapies. The second chapter discusses chemical modifications of nanostructured porous Si for stabilizing the material in biologically relevant media while providing an extended release of a therapeutic in vitro. This chapter also demonstrates the utility of the porous silicon optical signatures for effectively monitoring drug release from the system and its applications for development of a self-reporting drug delivery device. In chapter three, the concept of providing a triggered release of a therapeutic from porous silicon microparticles through initiation by an external stimulus is demonstrated. The microparticles are chemically modified, and the release is enhanced by a short application of ultrasound to the particulate system. The effect of ultrasound on the drug release and particle size is discussed. Chapter four presents a new method for sustaining the release of a monoclonal antibody from the porous matrix of porous SiO2. The therapeutic is incorporated into the films through electrostatic adsorption and a slow release is observed in vitro. A new method of quantifying the extent of drug loading is monitored with interferometry. The last chapter of the thesis provides a basic in vivo toxicity study of various porous Si microparticles for intraocular applications. Three types of porous Si particles are fabricated and studied in a rabbit eye model. The toxicity studies were conducted by collaborators at the Shiley Eye Center, La Jolla, CA. This work, demonstrates the feasibility of developing a self

  18. Covalent incorporation of non-chemically modified gelatin into degradable PVA-tyramine hydrogels.

    Science.gov (United States)

    Lim, Khoon S; Alves, Marie H; Poole-Warren, Laura A; Martens, Penny J

    2013-09-01

    Development of tissue engineering solutions for biomedical applications has driven the need for integration of biological signals into synthetic materials. Approaches to achieve this typically require chemical modification of the biological molecules. Examples include chemical grafting of synthetic polymers onto protein backbones and covalent modification of proteins using crosslinkable functional groups. However, such chemical modification processes can cause protein degradation, denaturation or loss of biological activity due to side chain disruption. This study exploited the observation that native tyrosine rich proteins could be crosslinked via radical initiated bi-phenol bond formation without any chemical modification of the protein. A new, tyramine functionalised poly(vinyl alcohol) (PVA) polymer was synthesised and characterised. The tyramine modified PVA (PVA-Tyr) was fabricated into hydrogels using a visible light initiated crosslinking system. Mass loss studies showed that PVA-Tyr hydrogels were completely degraded within 19 days most likely via degradation of ester linkages in the network. Protein incorporation to form a biosynthetic hydrogel was achieved using unmodified gelatin, a protein derived from collagen and results showed that 75% of gelatin was retained in the gel post-polymerisation. Incorporation of gelatin did not alter the sol fraction, swelling ratio and degradation profile of the hydrogels, but did significantly improve the cellular interactions. Moreover, incorporation of as little as 0.01 wt% gelatin was sufficient to facilitate fibroblast adhesion onto PVA-Tyr/gelatin hydrogels. Overall, this study details the synthesis of a new functionalised PVA macromer and demonstrates that tyrosine containing proteins can be covalently incorporated into synthetic hydrogels using this innovative PVA-Tyr system. The resultant degradable biosynthetic hydrogels hold great promise as matrices for tissue engineering applications.

  19. MS-based analytical methodologies to characterize genetically modified crops.

    Science.gov (United States)

    García-Cañas, Virginia; Simó, Carolina; León, Carlos; Ibáñez, Elena; Cifuentes, Alejandro

    2011-01-01

    The development of genetically modified crops has had a great impact on the agriculture and food industries. However, the development of any genetically modified organism (GMO) requires the application of analytical procedures to confirm the equivalence of the GMO compared to its isogenic non-transgenic counterpart. Moreover, the use of GMOs in foods and agriculture faces numerous criticisms from consumers and ecological organizations that have led some countries to regulate their production, growth, and commercialization. These regulations have brought about the need of new and more powerful analytical methods to face the complexity of this topic. In this regard, MS-based technologies are increasingly used for GMOs analysis to provide very useful information on GMO composition (e.g., metabolites, proteins). This review focuses on the MS-based analytical methodologies used to characterize genetically modified crops (also called transgenic crops). First, an overview on genetically modified crops development is provided, together with the main difficulties of their analysis. Next, the different MS-based analytical approaches applied to characterize GM crops are critically discussed, and include "-omics" approaches and target-based approaches. These methodologies allow the study of intended and unintended effects that result from the genetic transformation. This information is considered to be essential to corroborate (or not) the equivalence of the GM crop with its isogenic non-transgenic counterpart.

  20. Immobilization of chemically modified horse radish peroxidase within activated alginate beads

    Directory of Open Access Journals (Sweden)

    Spasojević Dragica

    2014-01-01

    Full Text Available Immobilization of horse radish peroxidase (HRP within alginate beads was improved by chemical modification of the enzyme and polysaccharide chains. HRP and alginate were oxidized by periodate and subsequently modified with ethylenediamine. Highest specific activity of 0.43 U/ml of gel and 81 % of bound enzyme activity was obtained using aminated HRP and alginate oxidized by periodate. Immobilized enzyme retained 75 % of original activity after 2 days of incubation in 80 % (v/v dioxane and had increased activity at basic pH values compared to native enzyme. During repeated use in batch reactor for pyrogallol oxidation immobilized peroxidase retained 75 % of original activity. [Projekat Ministarstva nauke Republike Srbije, br. ON173017 i br. ON172049

  1. Genome mining expands the chemical diversity of the cyanobactin family to include highly modified linear peptides.

    Science.gov (United States)

    Leikoski, Niina; Liu, Liwei; Jokela, Jouni; Wahlsten, Matti; Gugger, Muriel; Calteau, Alexandra; Permi, Perttu; Kerfeld, Cheryl A; Sivonen, Kaarina; Fewer, David P

    2013-08-22

    Ribosomal peptides are produced through the posttranslational modification of short precursor peptides. Cyanobactins are a growing family of cyclic ribosomal peptides produced by cyanobacteria. However, a broad systematic survey of the genetic capacity to produce cyanobactins is lacking. Here we report the identification of 31 cyanobactin gene clusters from 126 genomes of cyanobacteria. Genome mining suggested a complex evolutionary history defined by horizontal gene transfer and rapid diversification of precursor genes. Extensive chemical analyses demonstrated that some cyanobacteria produce short linear cyanobactins with a chain length ranging from three to five amino acids. The linear peptides were N-prenylated and O-methylated on the N and C termini, respectively, and named aeruginosamide and viridisamide. These findings broaden the structural diversity of the cyanobactin family to include highly modified linear peptides with rare posttranslational modifications.

  2. A modified next reaction method for simulating chemical systems with time dependent propensities and delays.

    Science.gov (United States)

    Anderson, David F

    2007-12-01

    Chemical reaction systems with a low to moderate number of molecules are typically modeled as discrete jump Markov processes. These systems are oftentimes simulated with methods that produce statistically exact sample paths such as the Gillespie algorithm or the next reaction method. In this paper we make explicit use of the fact that the initiation times of the reactions can be represented as the firing times of independent, unit rate Poisson processes with internal times given by integrated propensity functions. Using this representation we derive a modified next reaction method and, in a way that achieves efficiency over existing approaches for exact simulation, extend it to systems with time dependent propensities as well as to systems with delays.

  3. Biosilica from Living Diatoms: Investigations on Biocompatibility of Bare and Chemically Modified Thalassiosira weissflogii Silica Shells

    Directory of Open Access Journals (Sweden)

    Stefania Roberta Cicco

    2016-12-01

    Full Text Available In the past decade, mesoporous silica nanoparticles (MSNs with a large surface area and pore volume have attracted considerable attention for their application in drug delivery and biomedicine. Here we propose biosilica from diatoms as an alternative source of mesoporous materials in the field of multifunctional supports for cell growth: the biosilica surfaces were chemically modified by traditional silanization methods resulting in diatom silica microparticles functionalized with 3-mercaptopropyl-trimethoxysilane (MPTMS and 3-aminopropyl-triethoxysilane (APTES. Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy analyses revealed that the –SH or –NH2 were successfully grafted onto the biosilica surface. The relationship among the type of functional groups and the cell viability was established as well as the interaction of the cells with the nanoporosity of frustules. These results show that diatom microparticles are promising natural biomaterials suitable for cell growth, and that the surfaces, owing to the mercapto groups, exhibit good biocompatibility.

  4. Structural resistance of chemically modified 1-D nanostructured titanates in inorganic acid environment

    Energy Technology Data Exchange (ETDEWEB)

    Marinkovic, Bojan A., E-mail: bojan@puc-rio.br [Departamento de Engenharia de Materiais, Pontificia Universidade Catolica de Rio de Janeiro-PUC-Rio, Rua Marques de Sao Vicente 225, Gavea, RJ (Brazil); Fredholm, Yann C. [Nanogavea-Nanotecnologia Sustentavel Ltda, Av. Padre Leonel Franca 150, Gavea, RJ (Brazil); Morgado, Edisson [PETROBRAS S.A./CENPES, Research and Development Centre, Av. Horacio Macedo, 950, Cidade Universitaria, 21941-915, Rio de Janeiro, RJ (Brazil); Jardim, Paula M.; Rizzo, Fernando [Departamento de Engenharia de Materiais, Pontificia Universidade Catolica de Rio de Janeiro-PUC-Rio, Rua Marques de Sao Vicente 225, Gavea, RJ (Brazil)

    2010-10-15

    Sodium containing one-dimensional nanostructured layered titanates (1-D NSLT) were produced both from commercial anatase powder and Brazilian natural rutile mineral sands by alkali hydrothermal process. The 1-D NSLT were chemically modified with proton, cobalt or iron via ionic exchange and all products were additionally submitted to intensive inorganic acid aging (pH = 0.5) for 28 days. The morphology and crystal structure transformations of chemically modified 1-D NSLT were followed by transmission electron microscopy, powder X-ray diffraction, selected area electron diffraction and energy dispersive spectroscopy. It was found that the original sodium rich 1-D NSLT and cobalt substituted 1-D NSLT were completely converted to rutile nanoparticles, while the protonated form was transformed in a 70%-30% (by weight) anatase-rutile nanoparticles mixture, very similar to that of the well-known TiO{sub 2}-photocatalyst P25 (Degussa). The iron substituted 1-D NSLT presented better acid resistance as 13% of the original structure and morphology remained, the rest being converted in rutile. A significant amount of remaining 1-D NSLT was also observed after the acid treatment of the product obtained from rutile sand. The results showed that phase transformation of NSLT into titanium dioxide polymorph in inorganic acid conditions were controllable by varying the exchanged cations. Finally, the possibility to transform, through acid aging, 1-D NSLT obtained from Brazilian natural rutile sand into TiO{sub 2}-polymorphs was demonstrated for the first time to the best of authors' knowledge, opening path for producing TiO{sub 2}-nanoproducts with different morphologies through a simple process and from a low cost precursor.

  5. Genetic and chemical modifiers of a CUG toxicity model in Drosophila.

    Directory of Open Access Journals (Sweden)

    Amparo Garcia-Lopez

    Full Text Available Non-coding CUG repeat expansions interfere with the activity of human Muscleblind-like (MBNL proteins contributing to myotonic dystrophy 1 (DM1. To understand this toxic RNA gain-of-function mechanism we developed a Drosophila model expressing 60 pure and 480 interrupted CUG repeats in the context of a non-translatable RNA. These flies reproduced aspects of the DM1 pathology, most notably nuclear accumulation of CUG transcripts, muscle degeneration, splicing misregulation, and diminished Muscleblind function in vivo. Reduced Muscleblind activity was evident from the sensitivity of CUG-induced phenotypes to a decrease in muscleblind genetic dosage and rescue by MBNL1 expression, and further supported by the co-localization of Muscleblind and CUG repeat RNA in ribonuclear foci. Targeted expression of CUG repeats to the developing eye and brain mushroom bodies was toxic leading to rough eyes and semilethality, respectively. These phenotypes were utilized to identify genetic and chemical modifiers of the CUG-induced toxicity. 15 genetic modifiers of the rough eye phenotype were isolated. These genes identify putative cellular processes unknown to be altered by CUG repeat RNA, and they include mRNA export factor Aly, apoptosis inhibitor Thread, chromatin remodelling factor Nurf-38, and extracellular matrix structural component Viking. Ten chemical compounds suppressed the semilethal phenotype. These compounds significantly improved viability of CUG expressing flies and included non-steroidal anti-inflammatory agents (ketoprofen, muscarinic, cholinergic and histamine receptor inhibitors (orphenadrine, and drugs that can affect sodium and calcium metabolism such as clenbuterol and spironolactone. These findings provide new insights into the DM1 phenotype, and suggest novel candidates for DM1 treatments.

  6. Effect of chemically converted graphene as an electrode interfacial modifier on device-performances of inverted organic photovoltaic cells

    Science.gov (United States)

    Kang, Tae-Woon; Noh, Yong-Jin; Yun, Jin-Mun; Yang, Si-Young; Yang, Yong-Eon; Lee, Hae-Seong; Na, Seok-In

    2015-06-01

    This study examined the effects of chemically converted graphene (CCG) materials as a metal electrode interfacial modifier on device-performances of inverted organic photovoltaic cells (OPVs). As CCG materials for interfacial layers, a conventional graphene oxide (GO) and reduced graphene oxide (rGO) were prepared, and their functions on OPV-performances were compared. The inverted OPVs with CCG materials showed all improved cell-efficiencies compared with the OPVs with no metal/bulk-heterojunction (BHJ) interlayers. In particular, the inverted OPVs with reduction form of GO showed better device-performances than those with GO and better device-stability than poly(3,4-ethylenedioxythiophene): poly(styrenesulfonate) (PEDOT:PSS)-based inverted solar cells, showing that the rGO can be more desirable as a metal/BHJ interfacial material for fabricating inverted-configuration OPVs.

  7. Modified maximum likelihood registration based on information fusion

    Institute of Scientific and Technical Information of China (English)

    Yongqing Qi; Zhongliang Jing; Shiqiang Hu

    2007-01-01

    The bias estimation of passive sensors is considered based on information fusion in multi-platform multisensor tracking system. The unobservable problem of bearing-only tracking in blind spot is analyzed. A modified maximum likelihood method, which uses the redundant information of multi-sensor system to calculate the target position, is investigated to estimate the biases. Monte Carlo simulation results show that the modified method eliminates the effect of unobservable problem in the blind spot and can estimate the biases more rapidly and accurately than maximum likelihood method. It is statistically efficient since the standard deviation of bias estimation errors meets the theoretical lower bounds.

  8. Chemically Modified Plastic Tube for High Volume Removal and Collection of Circulating Tumor Cells.

    Directory of Open Access Journals (Sweden)

    Angelo Gaitas

    Full Text Available In this preliminary effort, we use a commercially available and chemically modified tube to selectively capture circulating tumor cells (CTCs from the blood stream by immobilizing human anti-EpCAM antibodies on the tube's interior surface. We describe the requisite and critical steps required to modify a tube into a cancer cell-capturing device. Using these simple modifications, we were able to capture or entrap about 85% of cancer cells from suspension and 44% of cancer cells from spiked whole blood. We also found that the percentage of cells captured was dependent on the tube's length and also the number of cancer cells present. It is our strong belief that with the utilization of appropriate tube lengths and procedures, we can ensure capture and removal of nearly the entire CTC population in whole blood. Importantly after a patient's entire blood volume has circulated through the tube, the tube can then be trypsinized to release the captured live CTCs for further analysis and testing.

  9. New Inorganic-organic Hybrid Tetravanadate:Preparation, Characterization and Application in Chemically Modified Electrode

    Institute of Scientific and Technical Information of China (English)

    SUN Ying-hua; LI Xiao-ping; MEI Ze-min; ZHU Yu; NIU Li

    2011-01-01

    A new inorganic-organic hybrid tetravanadate [Co(2,2'-bpy)3]2V4O12.llH2O(l) has been prepared and characterized. X-Ray diffraction study reveals that compound 1 contains classical cluster anions [V4O12]4-, coordi nated cations [Co(2,2'-bpy)3]2+ and eleven water molecules, in which an interesting decamer water cluster is formed.The hybrid nanoparticles were firstly used as a bulk-modifier to fabricate a chemically modified paste electrode (1-CPE). The electrochemical behavior and electrocatalysis of 1-CPE have been studied in detail. The results indicate that 1-CPE has a good electrocatalytic activity toward the reduction of bromate in a 0.5 mol/L H2SO4 aqueous solu tion. I-CPE shows remarkable stability that be ascribed to the hydrogen bonding interactions between V4O12 cluster and water cluster, which are very important for practical application in electrode modification.

  10. Amineborane Based Chemical Hydrogen Storage - Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Sneddon, Larry G.

    2011-04-21

    The development of efficient and safe methods for hydrogen storage is a major hurdle that must be overcome to enable the use of hydrogen as an alternative energy carrier. The objectives of this project in the DOE Center of Excellence in Chemical Hydride Storage were both to develop new methods for on-demand, low temperature hydrogen release from chemical hydrides and to design high-conversion off-board methods for chemical hydride regeneration. Because of their reactive protic (N-H) and hydridic (B-H) hydrogens and high hydrogen contents, amineboranes such as ammonia borane, NH3BH3 (AB), 19.6-wt% H2, and ammonia triborane NH3B3H7 (AT), 17.7-wt% H2, were initially identified by the Center as promising, high-capacity chemical hydrogen storage materials with the potential to store and deliver molecular hydrogen through dehydrogenation and hydrolysis reactions. In collaboration with other Center partners, the Penn project focused both on new methods to induce amineborane H2-release and on new strategies for the regeneration the amineborane spent-fuel materials. The Penn approach to improving amineborane H2-release focused on the use of ionic liquids, base additives and metal catalysts to activate AB dehydrogenation and these studies successfully demonstrated that in ionic liquids the AB induction period that had been observed in the solid-state was eliminated and both the rate and extent of AB H2-release were significantly increased. These results have clearly shown that, while improvements are still necessary, many of these systems have the potential to achieve DOE hydrogen-storage goals. The high extent of their H2­-release, the tunability of both their H2 materials weight-percents and release rates, and their product control that is attained by either trapping or suppressing unwanted volatile side products, such as borazine, continue to make AB/ionic­-liquid based systems attractive candidates for chemical hydrogen storage applications. These studies also

  11. Modified calcium oxide as stable solid base catalyst for Aldol condensation reaction

    Indian Academy of Sciences (India)

    Ying Tang; Jingfang Xu; Xuefan Gu

    2013-03-01

    A highly efficient and stable solid-base catalyst for Aldol condensation was prepared by modifying commercial CaO with benzyl bromide in a simple way. It was found that modified CaO can effectively catalyse the Aldol condensation of cyclohexanone and benzaldehyde, as well as various benzaldehydes, to produce 2-benzylidenecyclohexanone with a good selectivity and high yield. Higher yield of 95.8% was obtained over modified CaO after 3 h, which is short compared with the yield of 92.1% after 12 h over commercial CaO. The influence of several reaction parameters, such as temperature, catalyst loading, was investigated. The humidity test over modified CaO reveals that the basic centres of modified CaO are stable for CO2 and moisture. From the results of Fourier transform-infrared (FT-IR) and Thermogravity analysis (TG) characterization, the modifier was bonded on surface of CaO chemically and almost no Ca(OH)2 formed during the modification process. The type of aldehyde has great influence on the yield of aldol condensation.

  12. Carbon-Nanotube-Based Chemical Gas Sensor

    Science.gov (United States)

    Kaul, Arunpama B.

    2010-01-01

    Conventional thermal conductivity gauges (e.g. Pirani gauges) lend themselves to applications such as leak detectors, or in gas chromatographs for identifying various gas species. However, these conventional gauges are physically large, operate at high power, and have a slow response time. A single-walled carbon-nanotube (SWNT)-based chemical sensing gauge relies on differences in thermal conductance of the respective gases surrounding the CNT as it is voltage-biased, as a means for chemical identification. Such a sensor provides benefits of significantly reduced size and compactness, fast response time, low-power operation, and inexpensive manufacturing since it can be batch-fabricated using Si integrated-circuit (IC) process technology.

  13. Effect of Modifying Prosthetic Socket Base Materials by Adding Nanodiamonds

    Directory of Open Access Journals (Sweden)

    Lifang Ma

    2015-01-01

    Full Text Available The curing process of prosthetic socket base materials requires attention owing to a series of associated problems that are yet to be addressed and solved. However, to date, few relevant studies have been reported. In this paper, nanodiamonds modified with a silane coupling agent were dispersed into a prosthetic socket base material, and the performance of the modified base materials was investigated. Adding a predetermined amount of nanodiamonds to the prosthetic socket base material increased the glass transition temperature, improved the mechanical properties of the cured base material, and reduced the influence of the volatile gas formed during the curing process on the environment. With increasing nanodiamond contents, the glass transition temperature increased and the mechanical properties improved slightly. Owing to the high thermal conductivity of the nanodiamonds, the localized heat, as a result of the curing process, could be dissipated and released. Thus, adding nanodiamonds led to a more uniform temperature field forming in the curing system. This improved the curing process and reduced the formation of volatile monomers, thereby decreasing the adverse impact of the generated volatile gases on the environment. All of these provide a potential strategy for modifying prosthetic socket base materials.

  14. Kinetic and thermodynamic studies on biosorption of Cu(Ⅱ) by chemically modified orange peel

    Institute of Scientific and Technical Information of China (English)

    FENG Ning-chuan; GUO Xue-yi; LIANG Sha

    2009-01-01

    Cu(H) biosorption by orange peel that was chemically modified with sodium hydroxide and calcium chloride was investigated. The effects of temperature, contact time, initial concentration of metal ions and pH on the biosorption of Cu( II) ions were assessed. Thermodynamic parameters including change of free energy(△G~Θ), enthalpy (△H~Θ) and entropy(△S~Θ) during the biosorption were determined. The results show that the biosorption process of Cu( II) ions by chemically treated orange peel is feasible, spontaneous and exothermic under studied conditions. Equilibrium is well described by Langmuir equation with the maximum biosorption capacity(q_m) for Cu( II) as 72.73 mg/g and kinetics is found to fit pseudo-second order type biosorption kinetics. As the temperature increases from 16 ℃ to 60 ℃, copper biosorption decreases. The loaded biosorbent is regenerated using HC1 solution for repeatedly use for five times with little loss of biosorption capacity.

  15. On the structure and topography of free-standing chemically modified graphene

    Energy Technology Data Exchange (ETDEWEB)

    Wilson, N R; Pandey, P A; Beanland, R; Lupo, U; Rowlands, G; Roemer, R A [Department of Physics, University of Warwick, Gibbet Hill Road, Coventry, CV4 7AL (United Kingdom); Rourke, J P, E-mail: Neil.Wilson@Warwick.ac.uk [Department of Chemistry, University of Warwick, Gibbet Hill Road, Coventry, CV4 7AL (United Kingdom)

    2010-12-15

    The mechanical, electrical and chemical properties of chemically modified graphene (CMG) are intrinsically linked to its structure. Here, we report on our study of the topographic structure of free-standing CMG using atomic force microscopy (AFM) and electron diffraction. We find that, unlike graphene, suspended sheets of CMG are corrugated and distorted on nanometre length scales. AFM reveals not only long-range (100 nm) distortions induced by the support, as previously observed for graphene, but also short-range corrugations with length scales down to the resolution limit of 10 nm. These corrugations are static not dynamic, and are significantly diminished on CMG supported on atomically smooth substrates. Evidence for even shorter-range distortions, down to a few nanometres or less, is found by electron diffraction of suspended CMG. Comparison of the experimental data with simulations reveals that the mean atomic displacement from the nominal lattice position is of order 10% of the carbon-carbon bond length. Taken together, these results suggest a complex structure for CMG where heterogeneous functionalization creates local strain and distortion.

  16. On the structure and topography of free-standing chemically modified graphene

    Science.gov (United States)

    Wilson, N. R.; Pandey, P. A.; Beanland, R.; Rourke, J. P.; Lupo, U.; Rowlands, G.; Römer, R. A.

    2010-12-01

    The mechanical, electrical and chemical properties of chemically modified graphene (CMG) are intrinsically linked to its structure. Here, we report on our study of the topographic structure of free-standing CMG using atomic force microscopy (AFM) and electron diffraction. We find that, unlike graphene, suspended sheets of CMG are corrugated and distorted on nanometre length scales. AFM reveals not only long-range (100 nm) distortions induced by the support, as previously observed for graphene, but also short-range corrugations with length scales down to the resolution limit of 10 nm. These corrugations are static not dynamic, and are significantly diminished on CMG supported on atomically smooth substrates. Evidence for even shorter-range distortions, down to a few nanometres or less, is found by electron diffraction of suspended CMG. Comparison of the experimental data with simulations reveals that the mean atomic displacement from the nominal lattice position is of order 10% of the carbon-carbon bond length. Taken together, these results suggest a complex structure for CMG where heterogeneous functionalization creates local strain and distortion.

  17. The effects of space radiation on a chemically modified graphite-epoxy composite material

    Science.gov (United States)

    Reed, S. M.; Herakovich, C. T.; Sykes, G. F.

    1986-01-01

    The effects of the space environment on the engineering properties and chemistry of a chemically modified T300/934 graphite-epoxy composite system are characterized. The material was subjected to 1.0 x 10 to the 10th power rads of 1.0 MeV electron irradiation under vacuum to simulate 30 years in geosynchronous earth orbit. Monotonic tension tests were performed at room temperature (75 F/24 C) and elevated temperature (250 F/121 C) on 4-ply unidirectional laminates. From these tests, inplane engineering and strength properties (E sub 1, E sub 2, Nu sub 12, G sub 12, X sub T, Y sub T) were determined. Cyclic tests were also performed to characterize energy dissipation changes due to irradiation and elevated temperature. Large diameter graphite fibers were tested to determine the effects of radiation on their stiffness and strength. No significant changes were observed. Dynamic-mechanical analysis demonstrated that the glass transition temperature was reduced by 50 F(28 C) after irradiation. Thermomechanical analysis showed the occurrence of volatile products generated upon heating of the irradiated material. The chemical modification of the epoxy did not aid in producing a material which was more radiation resistant than the standard T300/934 graphite-epoxy system. Irradiation was found to cause crosslinking and chain scission in the polymer. The latter produced low molecular weight products which plasticize the material at elevated temperatures and cause apparent material stiffening at low stresses at room temperature.

  18. Applicability and Optimal Parameters Analysis for Chemical Phosphorus Removal in a Modified Carrousel Oxidation Ditch

    Directory of Open Access Journals (Sweden)

    Tao Zhang

    2017-07-01

    Full Text Available In order to confine the aqua-eutrophication problem arising from phosphorus pollution, many municipal wastewater treatment plants have to improve their executive drainage standard for total phosphorus (TP. In this study, a municipal wastewater treatment plant employing modified Carrousel oxidation ditch as main biological treatment unit was selected as a representative case. Technical necessity for adding a chemically enhanced phosphorus removal unit was analysed, and process feasibility was verified by batch and continuous experiments as well. The study results were summarized as follows. Because the organic carbon source in influent wastewater is not enough, it is impossible to satisfy the national drainage standard of TP by individual biological phosphorus removal processes, therefore, aided chemical phosphorus removal is essential. The polymeric aluminium chloride (PAC is preferable to be used as precipitant for phosphorus removal. The molar ratio of agent dosage to TP removal is preferable to be about 2.0. Under these conditions, the effluent TP concentration can be lower than 1.0 mg l−1.

  19. Efficiency of modified chemical remediation techniques for soil contaminated by organochlorine pesticides

    Science.gov (United States)

    Correa-Torres, S. N.; Kopytko, M.; Avila, S.

    2016-07-01

    This study reports the optimization of innovation chemical techniques in order to improve the remediation of soils contaminated with organochloride pesticides. The techniques used for remediation were dehalogenation and chemical oxidation in soil contaminated by pesticides. These techniques were applied sequentially and combined to evaluate the design optimize the concentration and contact time variables. The soil of this study was collect in cotton crop zone in Agustin Codazzi municipality, Colombia, and its physical properties was measure. The modified dehalogenation technique of EPA was applied on the contaminated soil by adding Sodium Bicarbonate solution at different concentrations and rates during 4, 7 and 14 days, subsequently oxidation technique was implemented by applying a solution of KMnO4 at different concentration and reaction times. Organochlorine were detected by Gas Chromatography analysis coupled Mass Spectrometry and its removals were between 85.4- 90.0% of compounds such as 4, 4’-DDT, 4,4’-DDD, 4,4-DDE, trans-Clordane y Endrin. These results demonstrate that the technique of dehalogenation with oxidation chemistry can be used for remediation soils contaminated by organochloride pesticides.

  20. [The influence of chemically-modified SLA on bone defect healing around implants in dogs].

    Science.gov (United States)

    Lv, Xiao-fei; Zhuang, Long-fei; Liu, Xin; Zhang, Zhi-yong; Lai, Hong-chang

    2010-06-01

    The study was designed to investigate the effect of surface chemical modification on the process of bone defect healing around implants in dogs. Six Beagle dogs were used in this study. The mandibular premolars and first molars were extracted bilaterally. Three months after tooth extraction the procedure of implant placement was performed. Four canals with a diameter of 2.8 mm and 10 mm in depth were prepared at the third premolar (P3) and the first molar (M1) sites of both sides of the mandible, of which the coronal 5 mm portion were further widened with the 5.3 mm diameter twist drill. In each side of the mandible one modSLA (chemically-modified SLA) implant and one SLA (sandblasted, large-grit, acid-etched) implant with a diameter of 3.3 mm and 10 mm in length were installed, respectively. Thus, the circumferential defect that was 5mm deep and 1mm wide created between the implant surface and the bony wall. Four implants placed in both sides of the mandible were allowed for non-submerged healing. Two dogs were sacrificed at the week 2, 4 and 8 following implant placement, respectively, and the specimens were prepared and stained with trinitrophenol- fuchsin for histological and histomorphometric analyses to acquire the bone-to-implant contact (BIC%), new bone fill (NBF%) and the distance between the most coronal level of bone-to-implant contact and the bottom of the surgically created bone defect(B-D). Statistical analysis was conducted with SPSS13.0 software package. No implant was loosen or lost during the study. The histomorphometric results demonstrated that new bone formation was observed in the defect region around both groups of implants at all time points and the newly formed bone occurred initially from the apical and lateral bony wall of the defect region, the bone defect almost was filled at week 8. At 2 and 4 weeks of healing, the BIC%, NBF% and B-D values were significantly higher for modSLA implants (P0.05). The SLA implants processed by means of

  1. Surface chemical and biological characterization of flax fabrics modified with silver nanoparticles for biomedical applications

    Energy Technology Data Exchange (ETDEWEB)

    Paladini, F., E-mail: federica.paladini@unisalento.it [Department of Engineering for Innovation, University of Salento, Via per Monteroni, 73100 Lecce (Italy); Picca, R.A.; Sportelli, M.C.; Cioffi, N. [Department of Chemistry, University of Bari “Aldo Moro”, Via Orabona 4, 70126 Bari (Italy); Sannino, A.; Pollini, M. [Department of Engineering for Innovation, University of Salento, Via per Monteroni, 73100 Lecce (Italy)

    2015-07-01

    Silver nanophases are increasingly used as effective antibacterial agent for biomedical applications and wound healing. This work aims to investigate the surface chemical composition and biological properties of silver nanoparticle-modified flax substrates. Silver coatings were deposited on textiles through the in situ photo-reduction of a silver solution, by means of a large-scale apparatus. The silver-coated materials were characterized through X-ray Photoelectron Spectroscopy (XPS), to assess the surface elemental composition of the coatings, and the chemical speciation of both the substrate and the antibacterial nanophases. A detailed investigation of XPS high resolution regions outlined that silver is mainly present on nanophases' surface as Ag{sub 2}O. Scanning electron microscopy and energy dispersive X-ray spectroscopy were also carried out, in order to visualize the distribution of silver particles on the fibers. The materials were also characterized from a biological point of view in terms of antibacterial capability and cytotoxicity. Agar diffusion tests and bacterial enumeration tests were performed on Gram positive and Gram negative bacteria, namely Staphylococcus aureus and Escherichia coli. In vitro cytotoxicity tests were performed through the extract method on murine fibroblasts in order to verify if the presence of the silver coating affected the cellular viability and proliferation. Durability of the coating was also assessed, thus confirming the successful scaling up of the process, which will be therefore available for large-scale production. - Highlights: • Silver nanophases are increasingly used as effective antibacterial agent for biomedical applications. • Silver coatings were deposited on textiles through the in situ photo-reduction of a silver solution. • Flax fabrics were characterized from a biological and surface chemical point of view. • Scaling up of the process was confirmed.

  2. Adhesion force interactions between cyclopentane hydrate and physically and chemically modified surfaces.

    Science.gov (United States)

    Aman, Zachary M; Sloan, E Dendy; Sum, Amadeu K; Koh, Carolyn A

    2014-12-07

    Interfacial interactions between liquid-solid and solid-solid phases/surfaces are of fundamental importance to the formation of hydrate deposits in oil and gas pipelines. This work establishes the effect of five categories of physical and chemical modification to steel on clathrate hydrate adhesive force: oleamide, graphite, citric acid ester, nonanedithiol, and Rain-X anti-wetting agent. Hydrate adhesive forces were measured using a micromechanical force apparatus, under both dry and water-wet surface conditions. The results show that the graphite coating reduced hydrate-steel adhesion force by 79%, due to an increase in the water wetting angle from 42 ± 8° to 154 ± 7°. Two chemical surface coatings (nonanedithiol and the citric acid ester) induced rapid hydrate growth in the hydrate particles; nonanedithiol increased hydrate adhesive force by 49% from the baseline, while the citric acid ester coating reduced hydrate adhesion force by 98%. This result suggests that crystal growth may enable a strong adhesive pathway between hydrate and other crystalline structures, however this effect may be negated in cases where water-hydrocarbon interfacial tension is minimised. When a liquid water droplet was placed on the modified steel surfaces, the graphite and citric acid ester became less effective at reducing adhesive force. In pipelines containing a free water phase wetting the steel surface, chemical or physical surface modifications alone may be insufficient to eliminate hydrate deposition risk. In further tests, the citric acid ester reduced hydrate cohesive forces by 50%, suggesting mild activity as a hybrid anti-agglomerant suppressing both hydrate deposition and particle agglomeration. These results demonstrate a new capability to develop polyfunctional surfactants, which simultaneously limit the capability for hydrate particles to aggregate and deposit on the pipeline wall.

  3. Electrochemical investigation of the surface-modifying roles of guanidine carbonate in chemical mechanical planarization of tantalum

    Energy Technology Data Exchange (ETDEWEB)

    Rock, S.E.; Crain, D.J.; Zheng, J.P. [Department of Physics, Clarkson University, Potsdam, NY 13699-5820 (United States); Pettit, C.M. [Department of Physics, Emporia State University, Emporia, KS 66801-5087 (United States); Roy, D., E-mail: samoy@clarkson.edu [Department of Physics, Clarkson University, Potsdam, NY 13699-5820 (United States)

    2011-10-03

    Highlights: {yields} This work contributes to the development of CMP slurries for Ta and Cu at low pressure. {yields} We present here a model of the chemical mechanism of the CMP of Ta and Cu using guanidine slurries. {yields} Removal of Ta occurs as structurally weak guanidinium-tantalic-acid surface complexes. {yields} The results will be useful for the CMP processing of interconnects with low-k dielectrics. {yields} We demonstrate the utility of electro-analytical techniques in the development of CMP slurries. - Abstract: The fabrication of interconnect structures for semiconductor devices requires low down-pressure chemical mechanical planarization (CMP) of Ta barrier layers. Guanidine carbonate (GC) serves as an effective surface-complexing agent for such CMP applications, where the rate of Ta removal can be chemically controlled through pH-tuned selectivity with respect to the removal of Cu lines. Electrochemical techniques are employed in this work to study the surface-modifying roles of GC that make this chemical an attractive complexing agent for Ta CMP. In addition, the effects of including H{sub 2}O{sub 2} (an oxidizer) and dodecyl benzene sulfonic acid (DBSA, a dissolution inhibitor for Cu) in GC-based CMP solutions are investigated to examine the selective CMP mechanisms of Ta and Cu in these solutions. The results suggest that the removal of Ta is supported in part by structurally weak guanidinium-tantalic-acid surface complexes formed on Ta/Ta{sub 2}O{sub 5}. The bicarbonate/carbonate anions of GC also facilitate Ta removal through 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.

  4. Trimethylamine Sensors Based on Au-Modified Hierarchical Porous Single-Crystalline ZnO Nanosheets

    Directory of Open Access Journals (Sweden)

    Fanli Meng

    2017-06-01

    Full Text Available It is of great significance for dynamic monitoring of foods in storage or during the transportation process through on-line detecting trimethylamine (TMA. Here, TMA were sensitively detected by Au-modified hierarchical porous single-crystalline ZnO nanosheets (HPSCZNs-based sensors. The HPSCZNs were synthesized through a one-pot wet-chemical method followed by an annealing treatment. Polyethyleneimine (PEI was used to modify the surface of the HPSCZNs, and then the PEI-modified samples were mixed with Au nanoparticles (NPs sol solution. Electrostatic interactions drive Au nanoparticles loading onto the surface of the HPSCZNs. The Au-modified HPSCZNs were characterized by X-ray diffraction (XRD, scanning electron microscopy (SEM, transmission electron microscopy (TEM and energy dispersive spectrum (EDS, respectively. The results show that Au-modified HPSCZNs-based sensors exhibit a high response to TMA. The linear range is from 10 to 300 ppb; while the detection limit is 10 ppb, which is the lowest value to our knowledge.

  5. Chemically Modified Oligonucleotides Modulate an Epigenetically Varied and Transient Form of Transcription Silencing of HIV-1 in Human Cells

    Directory of Open Access Journals (Sweden)

    Stuart Knowling

    2012-01-01

    Full Text Available Small noncoding RNAs (ncRNAs have been shown to guide epigenetic silencing complexes to target loci in human cells. When targeted to gene promoters, these small RNAs can lead to long-term stable epigenetic silencing of gene transcription. To date, small RNAs have been shown to modulate transcriptional gene silencing (TGS of human immunodeficiency virus type 1 (HIV-1 as well as several other disease-related genes, but it has remained unknown as to what extent particular chemistries can be used to generate single-stranded backbone-modified oligonucleotides that are amenable to this form of gene targeting and regulation. Here, we present data indicating that specific combinations of backbone modifications can be used to generate single-stranded antisense oligonucleotides that can functionally direct TGS of HIV-1 in a manner that is however, independent of epigenetic changes at the target loci. Furthermore, this functionality appears contingent on the absence of a 5′ phosphate in the oligonucleotide. These data suggest that chemically modified oligonucleotide based approaches could be implemented as a means to regulate gene transcription in an epigenetically independent manner.

  6. Waveguide-based optical chemical sensor

    Science.gov (United States)

    Grace, Karen M.; Swanson, Basil I.; Honkanen, Seppo

    2007-03-13

    The invention provides an apparatus and method for highly selective and sensitive chemical sensing. Two modes of laser light are transmitted through a waveguide, refracted by a thin film host reagent coating on the waveguide, and analyzed in a phase sensitive detector for changes in effective refractive index. Sensor specificity is based on the particular species selective thin films of host reagents which are attached to the surface of the planar optical waveguide. The thin film of host reagents refracts laser light at different refractive indices according to what species are forming inclusion complexes with the host reagents.

  7. Effect of emulsifiers on complexation and retrogradation characteristics of native and chemically modified White sorghum (Sorghum bicolor) starch

    Energy Technology Data Exchange (ETDEWEB)

    Ali, Tahira Mohsin, E-mail: tahira.mohsin@uok.edu.pk [Department of Food Science and Technology, University of Karachi, 75270 Karachi (Pakistan); Hasnain, Abid, E-mail: abidhasnain@uok.edu.pk [Department of Food Science and Technology, University of Karachi, 75270 Karachi (Pakistan)

    2013-01-20

    Highlights: Black-Right-Pointing-Pointer Sorghum starches were chemically modified. Black-Right-Pointing-Pointer Starch-lipid complexes were studied in the presence of emulsifiers. Black-Right-Pointing-Pointer Type II complexes were also detected in native and oxidized starches on adding GMS. Black-Right-Pointing-Pointer Starch-lipid complexes sharply reduced retrogradation in modified starches. - Abstract: The effect of emulsifiers on complexation and retrogradation characteristics of native and chemically modified white sorghum starches was studied. Complex forming tendency of white sorghum starch with commercially available emulsifiers GMS and DATEM improved after acetylation. Presence of emulsifiers reduced {lambda}{sub max} (wavelength of maximum absorbance) both for native and modified sorghum starches suggesting lower availability of amylose chains to complex with iodine. In native white sorghum starch (NWSS) and oxidized white sorghum starch (OWSS), both Type I and Type II starch-lipid complexes were observed on addition of 1.0% GMS prior to gelatinization. Acetylated-oxidized white sorghum starch (AOWSS) formed weakest complexes among all the modified starches. The results revealed that antistaling characteristics of modified sorghum starches were enhanced when used in combination with emulsifiers. The most prominent decline in reassociative capability among modified starches was observed for acetylated starches.

  8. Sensing based on the motion of enzyme-modified nanorods

    DEFF Research Database (Denmark)

    Bunea, Ada-Ioana; Pavel, Ileana-Alexandra; David, Sorin;

    2015-01-01

    Asymmetric modification with an enzyme confers nanorods an enhanced diffusive motion that is dependent on the concentration of the enzyme substrate. In turn, such a motion opens the possibility of determining the concentration of the enzyme substrate by measuring the diffusion coefficient...... of nanorods modified with the appropriate enzyme. Nanorods, with a Pt and a polypyrrole (PPy) segment, were fabricated. The PPy segment of such nanorods was then modified with glucose oxidase (GOx), glutamate oxidase (GluOx), or xanthine oxidase (XOD). Calibration curves, linking the diffusion coefficient...... media. Based on the obtained results we are confident that our motion-based approach to sensing can be developed to the point where different nanorods in a mixture simultaneously report on the concentration of different compounds with good temporal and spatial resolution....

  9. Catechol-Based Hydrogel for Chemical Information Processing

    Directory of Open Access Journals (Sweden)

    Eunkyoung Kim

    2017-07-01

    Full Text Available Catechols offer diverse properties and are used in biology to perform various functions that range from adhesion (e.g., mussel proteins to neurotransmission (e.g., dopamine, and mimicking the capabilities of biological catechols have yielded important new materials (e.g., polydopamine. It is well known that catechols are also redox-active and we have observed that biomimetic catechol-modified chitosan films are redox-active and possess interesting molecular electronic properties. In particular, these films can accept, store and donate electrons, and thus offer redox-capacitor capabilities. We are enlisting these capabilities to bridge communication between biology and electronics. Specifically, we are investigating an interactive redox-probing approach to access redox-based chemical information and convert this information into an electrical modality that facilitates analysis by methods from signal processing. In this review, we describe the broad vision and then cite recent examples in which the catechol–chitosan redox-capacitor can assist in accessing and understanding chemical information. Further, this redox-capacitor can be coupled with synthetic biology to enhance the power of chemical information processing. Potentially, the progress with this biomimetic catechol–chitosan film may even help in understanding how biology uses the redox properties of catechols for redox signaling.

  10. Dental repair material: a resin-modified glass-ionomer bioactive ionic resin-based composite.

    Science.gov (United States)

    Croll, Theodore P; Berg, Joel H; Donly, Kevin J

    2015-01-01

    This report documents treatment and repair of three carious teeth that were restored with a new dental repair material that features the characteristics of both resin-modified glass-ionomer restorative cement (RMGI) and resin-based composite (RBC). The restorative products presented are reported by the manufacturer to be the first bioactive dental materials with an ionic resin matrix, a shock-absorbing resin component, and bioactive fillers that mimic the physical and chemical properties of natural teeth. The restorative material and base/liner, which feature three hardening mechanisms, could prove to be a notable advancement in the adhesive dentistry restorative materials continuum.

  11. Additives for cement compositions based on modified peat

    Science.gov (United States)

    Kopanitsa, Natalya; Sarkisov, Yurij; Gorshkova, Aleksandra; Demyanenko, Olga

    2016-01-01

    High quality competitive dry building mixes require modifying additives for various purposes to be included in their composition. There is insufficient amount of quality additives having stable properties for controlling the properties of cement compositions produced in Russia. Using of foreign modifying additives leads to significant increasing of the final cost of the product. The cost of imported modifiers in the composition of the dry building mixes can be up to 90% of the material cost, depending on the composition complexity. Thus, the problem of import substitution becomes relevant, especially in recent years, due to difficult economic situation. The article discusses the possibility of using local raw materials as a basis for obtaining dry building mixtures components. The properties of organo-mineral additives for cement compositions based on thermally modified peat raw materials are studied. Studies of the structure and composition of the additives are carried out by physicochemical research methods: electron microscopy and X-ray analysis. Results of experimental research showed that the peat additives contribute to improving of cement-sand mortar strength and hydrophysical properties.

  12. Additives for cement compositions based on modified peat

    Energy Technology Data Exchange (ETDEWEB)

    Kopanitsa, Natalya, E-mail: kopanitsa@mail.ru; Sarkisov, Yurij, E-mail: sarkisov@tsuab.ru; Gorshkova, Aleksandra, E-mail: kasatkina.alexandra@gmail.com; Demyanenko, Olga, E-mail: angel-n@sibmail.com [Tomsk State University of Architecture and Building, 2, Solyanaya sq., Tomsk, 634003 (Russian Federation)

    2016-01-15

    High quality competitive dry building mixes require modifying additives for various purposes to be included in their composition. There is insufficient amount of quality additives having stable properties for controlling the properties of cement compositions produced in Russia. Using of foreign modifying additives leads to significant increasing of the final cost of the product. The cost of imported modifiers in the composition of the dry building mixes can be up to 90% of the material cost, depending on the composition complexity. Thus, the problem of import substitution becomes relevant, especially in recent years, due to difficult economic situation. The article discusses the possibility of using local raw materials as a basis for obtaining dry building mixtures components. The properties of organo-mineral additives for cement compositions based on thermally modified peat raw materials are studied. Studies of the structure and composition of the additives are carried out by physicochemical research methods: electron microscopy and X-ray analysis. Results of experimental research showed that the peat additives contribute to improving of cement-sand mortar strength and hydrophysical properties.

  13. A genotype of modified vaccinia Ankara (MVA) that facilitates replication in suspension cultures in chemically defined medium.

    Science.gov (United States)

    Jordan, Ingo; Horn, Deborah; John, Katrin; Sandig, Volker

    2013-01-21

    While vectored vaccines, based on hyperattenuated viruses, may lead to new treatment options against infectious diseases and certain cancers, they are also complex products and sometimes difficult to provide in sufficient amount and purity. To facilitate vaccine programs utilizing host-restricted poxviruses, we established avian suspension cell lines (CR and CR.pIX) and developed a robust, chemically defined, culturing process for production of this class of vectors. For one prominent member, modified vaccinia Ankara (MVA), we now describe a new strain that appears to replicate to greater yields of infectious units, especially in the cell-free supernatant of cultures in chemically defined media. The new strain was obtained by repeated passaging in CR suspension cultures and, consistent with reports on the exceptional genetic stability of MVA, sequencing of 135 kb of the viral genomic DNA revealed that only three structural proteins (A3L, A9L and A34R) each carry a single amino acid exchange (H639Y, K75E and D86Y, respectively). Host restriction in a plaque-purified isolate of the new genotype appears to be maintained in cell culture. Processing towards an injectable vaccine preparation may be simplified with this strain as a complete lysate, containing the main burden of host cell contaminants, may not be required anymore to obtain adequate yields.

  14. A modified parallel artificial membrane permeability assay for evaluating the bioconcentration of highly hydrophobic chemicals in fish.

    Science.gov (United States)

    Kwon, Jung-Hwan; Escher, Beate I

    2008-03-01

    Low cost in vitro tools are needed at the screening stage of assessment of bioaccumulation potential of new and existing chemicals because the number of chemical substances that needs to be tested highly exceeds the capacity of in vivo bioconcentration tests. Thus, the parallel artificial membrane permeability assay (PAMPA) system was modified to predict passive uptake/ elimination rate in fish. To overcome the difficulties associated with low aqueous solubility and high membrane affinity of highly hydrophobic chemicals, we measured the rate of permeation from the donor poly(dimethylsiloxane)(PDMS) disk to the acceptor PDMS disk through aqueous and PDMS membrane boundary layers and term the modified PAMPA system "PDMS-PAMPA". Twenty chemicals were selected for validation of PDMS-PAMPA. The measured permeability is proportional to the passive elimination rate constant in fish and was used to predict the "minimum" in vivo elimination rate constant. The in vivo data were very close to predicted values except for a few polar chemicals and metabolically active chemicals, such as pyrene and benzo[a]pyrene. Thus, PDMS-PAMPA can be an appropriate in vitro system for nonmetabolizable chemicals. Combination with metabolic clearance rates using a battery of metabolic degradation assays would enhance the applicability for metabolizable chemicals.

  15. Supported liquid membrane stability in chiral resolution by chemically and physically modified membranes

    Energy Technology Data Exchange (ETDEWEB)

    Molinari, R.; Argurio, P. [Arcavata di Rende Univ. of Calabria, Arcavata di Rende, CS (Italy). Dept. of Chemical and Materials Engineering

    2001-04-01

    In the present work some stability studies on Supported Liquid Membranes (SLMs) to be used for chiral separations were realized. In particular, primary aim was to determine how a modification of the support surface influences the SLM stability. First, the procedure for support modification was optimised, making a screening of various compounds (sulphuric acid, nitric acid, chromic acid, sodium dodecyl sulphate (SDS), glycerol, oleic alcohol, propylene glycol (PPG), bovine serum albumin (BSA)) and testing their performance by means of contact angle measurements. Next, a second screening was realized by permeation tests in a stirred cell. Finally, to compare the stability of modified with unmodified support in a process of interest for chemical and/or biochemical industries, some permeation tests for resolution of DNB-DL-Leucine were realized in a re-circulation system. Results showed a better surface hydrophilization of chemically modified support and better stability of the sulphonated support. However, in operating conditions a little high stability of the unmodified support was obtained. [Italian] Nel presente lavoro sono stati realizzati degli studi di stabilita' di Membrane Liquide Supportate (SLMs) da impiegare in separazioni chirali. In particolare, obiettivo principale e' stato quello di determinare l'influenza che una modifica della superficie del supporto ha sulla stabilita' della SLM. Cosi', in un primo momento, e' stata ottimizzata le procedura di modifica del supporto, facendo una selezione tra vari composti (acido solforico, acido nitrico, acido cromico, sodio dodecil solfato (SDS), glicerolo, alcool oleico, glicole propilenico (PPG), siero di albumina bovina (BSA)) basata su misure dell'angolo di contatto. Successivamente, e' stata realizzata una seconda selezione mediante prove di permeazione in una cella agitata. Infine, con lo scopo di confrontare la stabilita' della SLM con supporto modificato rispetto

  16. Electron Transfer Reactivity Patterns at Chemically Modified Electrodes: Fundamentals and Application to the Optimization of Redox Recycling Amplification Systems

    Energy Technology Data Exchange (ETDEWEB)

    Bergren, Adam Johan [Iowa State Univ., Ames, IA (United States)

    2006-01-01

    Electroanalytical chemistry is often utilized in chemical analysis and Fundamental studies. Important advances have been made in these areas since the advent of chemically modified electrodes: the coating of an electrode with a chemical film in order to impart desirable, and ideally, predictable properties. These procedures enable the exploitation of unique reactivity patterns. This dissertation presents studies that investigate novel reaction mechanisms at self-assembled monolayers on gold. In particular, a unique electrochemical current amplification scheme is detailed that relies on a selective electrode to enable a reactivity pattern that results in regeneration of the analyte (redox recycling). This regenerating reaction can occur up to 250 times for each analyte molecule, leading to a notable enhancement in the observed current. The requirements of electrode selectivity and the resulting amplification and detection limit improvements are described with respect to the heterogeneous and homogeneous electron transfer rates that characterize the system. These studies revealed that the heterogeneous electrolysis of the analyte should ideally be electrochemically reversible, while that for the regenerating agent should be held to a low level. Moreover, the homogeneous reaction that recycles the analyte should occur at a rapid rate. The physical selectivity mechanism is also detailed with respect to the properties of the electrode and redox probes utilized. It is shown that partitioning of the analyte into/onto the adlayer leads to the extraordinary selectivity of the alkanethiolate monolayer modified electrode. Collectively, these studies enable a thorough understanding of the complex electrode mechanism required for successful redox recycling amplification systems, Finally, in a separate (but related) study, the effect of the akyl chain length on the heterogeneous electron transfer behavior of solution-based redox probes is reported, where an odd-even oscillation

  17. Gravimetric chemical sensors based on silica-based mesoporous organic-inorganic hybrids.

    Science.gov (United States)

    Xu, Jiaqiang; Zheng, Qi; Zhu, Yongheng; Lou, Huihui; Xiang, Qun; Cheng, Zhixuan

    2014-09-01

    Silica-based mesoporous organic-inorganic hybrid material modified quartz crystal microbalance (QCM) sensors have been examined for their ability to achieve highly sensitive and selective detection. Mesoporous silica SBA-15 serves as an inorganic host with large specific surface area, facilitating gas adsorption, and thus leads to highly sensitive response; while the presence of organic functional groups contributes to the greatly improved specific sensing property. In this work, we summarize our efforts in the rational design and synthesis of novel sensing materials for the detection of hazardous substances, including simulant nerve agent, organic vapor, and heavy metal ion, and develop high-performance QCM-based chemical sensors.

  18. Modified chemical synthesis of porous α-Sm{sub 2}S{sub 3} thin films

    Energy Technology Data Exchange (ETDEWEB)

    Kumbhar, V.S.; Jagadale, A.D. [Thin Film Physics Laboratory, Department of Physics, Shivaji University, Kolhapur, (M.S.) 416004 (India); Gaikwad, N.S. [Rayat Shikshan Sanstha, Satara, (M.S.) 415 001 (India); Lokhande, C.D., E-mail: l_chandrakant@yahoo.com [Thin Film Physics Laboratory, Department of Physics, Shivaji University, Kolhapur, (M.S.) 416004 (India)

    2014-08-15

    Highlights: • A novel chemical route to prepare α-Sm{sub 2}S{sub 3} thin films. • A porous honeycomb like morphology of the α-Sm{sub 2}S{sub 3} thin film. • An application of α-Sm{sub 2}S{sub 3} thin film toward its supercapacitive behaviour. - Abstract: The paper reports synthesis of porous α-Sm{sub 2}S{sub 3} thin films using modified chemical synthesis, also known as successive ionic layer adsorption and reaction (SILAR) method. The X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), atomic force microscopy (AFM), wettability and ultraviolet–visible spectroscopy (UV–vis) techniques are used for the study of structural, elemental, morphological and optical properties of α-Sm{sub 2}S{sub 3} films. An orthorhombic crystal structure of α-Sm{sub 2}S{sub 3} is resulted from XRD study. The SEM and AFM observations showed highly porous α-Sm{sub 2}S{sub 3} film surface. An optical band gap of 2.50 eV is estimated from optical absorption spectrum. The porous α-Sm{sub 2}S{sub 3} thin film tuned for supercapacitive behaviour using cyclic voltammetry and galvanostatic charge discharge showed a specific capacitance and energy density of 294 Fg{sup –1} and 48.9 kW kg{sup –1}, respectively in 1 M LiClO{sub 4}–propylene carbonate electrolyte.

  19. The chemical and catalytic properties of nanocrystalline metal oxides prepared through modified sol-gel synthesis

    Science.gov (United States)

    Carnes, Corrie Leigh

    The goal of this research was to synthesize, characterize and study the chemical properties of nanocrystalline metal oxides. Nanocrystalline (NC) ZnO, CuO, NiO, Al2O3, and the binary Al2O 3/MgO and ZnO/CuO were prepared through modified sol gel methods. These NC metal oxides were studied in comparison to the commercial (CM) metal oxides. The samples were characterized by XRD, TGA, FTIR, BET, and TEM. The NC samples were all accompanied by a significant increase in surface area and decrease in crystallite size. Several chemical reactions were studied to compare the NC samples to the CM samples. One of the reactions involved a high temperature reaction between carbon tetrachloride and the oxide to form carbon dioxide and the corresponding metal chloride. A similar high temperature reaction was conducted between the metal oxide and hydrogen sulfide to form water and the corresponding metal sulfide. A room temperature gas phase adsorption was studied where SO2 was adsorbed onto the oxide. A liquid phase adsorption conducted at room temperature was the destructive adsorption of paraoxon (a toxic insecticide). In all reactions the NC samples exhibited greater activity, destroying or adsorbing a larger amount of the toxins compared to the CM samples. To better study surface area effects catalytic reactions were also studied. The catalysis of methanol was studied over the nanocrystalline ZnO, CuO, NiO, and ZnO/CuO samples in comparison to their commercial counterparts. In most cases the NC samples proved to be more active catalysts, having higher percent conversions and turnover numbers. A second catalytic reaction was also studied, this reaction was investigated to look at the support effects. The catalysis of cyclopropane to propane was studied over Pt and Co catalysts. These catalysts were supported onto NC and CM alumina by impregnation. By observing differences in the catalytic behavior, support effects have become apparent.

  20. Distribution of phosphorus and hydroxypropyl groups within granules of modified sweet potato starches as determined after chemical peeling

    NARCIS (Netherlands)

    Zhao, J.; Schols, H.A.; Chen Zenghong,; Jin, Z.; Buwalda, P.; Gruppen, H.

    2015-01-01

    The distributions of phosphorus and hydroxypropyl groups within granules of cross-linked and hydroxypropylated sweet potato starches were investigated. Chemical surface peeling of starch granules was performed after sieving of native and modified starches into large-size (diameter = 20 µm) and small

  1. Enhanced forward osmosis from chemically modified polybenzimidazole (PBI) nanofiltration hollow fiber membranes with a thin wall

    KAUST Repository

    Wang, Kai Yu

    2009-04-01

    To develop high-flux and high-rejection forward osmosis (FO) membranes for water reuses and seawater desalination, we have fabricated polybenzimidazole (PBI) nanofiltration (NF) hollow fiber membranes with a thin wall and a desired pore size via non-solvent induced phase inversion and chemically cross-linking modification. The cross-linking by p-xylylene dichloride can finely tune the mean pore size and enhance the salt selectivity. High water permeation flux and improved salt selectivity for water reuses were achieved by using the 2-h modified PBI NF membrane which has a narrow pore size distribution. Cross-linking at a longer time produces even a lower salt permeation flux potentially suitable for desalination but at the expense of permeation flux due to tightened pore sizes. It is found that draw solution concentration and membrane orientations are main factors determining the water permeation flux. In addition, effects of membrane morphology and operation conditions on water and salt transport through membrane have been investigated. © 2008 Elsevier Ltd. All rights reserved.

  2. Photoelectrochemical Properties of CuO Grown by Using a Modified Chemical Bath Deposition Method

    Energy Technology Data Exchange (ETDEWEB)

    Ha, Jin-wook; Ryu, Hyukhyun [Inje University, Gimhae (Korea, Republic of); Lee, Won-Jae [Dong-Eui University, Busan (Korea, Republic of)

    2016-06-15

    In this study, cupric oxide (CuO) nanorods were grown on the fluorine-doped tin oxide (FTO) glass substrate using a modified-chemical bath deposition (M-CBD) method. We investigated the morphology, structural, optical and photoelectrochemical properties of the cupric oxide nanorods with various growth durations by using field-emission scanning-electron microscopy (FE-SEM), X-ray diffraction (XRD), UV-visible spectroscopy (UV-vis) and three-electrode potentiostat, respectively. In this work, we found that the morphologies, thickness, growth rate, crystallinities, grain sizes and optical bandgap were controllable on the growth duration, which affected photocurrent density and photo-stability. The highest growth rate of CuO nanorods was 126 nm/min. From the XRD measurement, we also confirmed that (020) directional growth affected the growth of the CuO nanorods. A maximum photocurrent density of-1.88 mA/cm² at -0.55 V (vs. SCE) and high photo-stability value about 40% was obtained with 10 minutes growth duration.

  3. Optimizing the lanthanum adsorption process onto chemically modified biomaterials using factorial and response surface design.

    Science.gov (United States)

    Gabor, Andreea; Davidescu, Corneliu Mircea; Negrea, Adina; Ciopec, Mihaela; Grozav, Ion; Negrea, Petru; Duteanu, Narcis

    2017-01-29

    The rare metals' potential to pollute air, water, soil, and especially groundwater has received lot of attention recently. One of the most common rare earth group elements, lanthanum, is used in many industrial branches, and due to its toxicity, it needs to be eliminated from all residual aqueous solutions. The goal of this study was to evaluate the control of the adsorption process for lanthanum removal from aqueous solutions, using cellulose, a known biomaterial with high adsorbent properties, cheap, and environment friendly. The cellulose was chemically modified by functionalization with sodium β-glycerophosphate. The experimental results obtained after factorial design indicate optimum adsorption parameters as pH 6, contact time 60 min, and temperature 298 K, when the equilibrium concentration of lanthanum was 250 mg L(-1), and the experimental adsorption capacity obtained was 31.58 mg g(-1). Further refinement of the optimization of the adsorption process by response surface design indicates that at pH 6 and the initial concentration of 256 mg L(-1), the adsorption capacity has maximum values between 30.87 and 36.73 mg g(-1).

  4. Removal of heavy metals from aqueous phases using chemically modified waste Lyocell fiber.

    Science.gov (United States)

    Bediako, John Kwame; Wei, Wei; Kim, Sok; Yun, Yeoung-Sang

    2015-12-15

    In this study, an outstanding performance of chemically modified waste Lyocell for heavy metals treatment is reported. The sorbent, which was prepared by a simple and concise method, was able to bind heavy metals such as Pb(II), Cu(II) and Cd(II), with very high efficiencies. The binding mechanisms were studied through adsorption and standard characterization tests such as scanning electron microscopy, energy-dispersive spectroscopy, Fourier transform infrared spectroscopy, and X-ray diffraction analyses. Adsorption kinetics was very fast and attained equilibrium within 5 min in all metals studied. The maximum single metal uptakes were 531.29±0.28 mg/g, 505.64±0.21 mg/g, and 123.08±0.26 mg/g for Pb(II), Cd(II) and Cu(II), respectively. In ternary metal systems, Cu(II) selectivity was observed and the underlying factors were discussed. The sorbent by its nature, could be very effective in treating large volumes of wastewater with the contact of very little amount.

  5. Removal of methylene blue from aqueous solutions by chemically modified bamboo.

    Science.gov (United States)

    Guo, Jian-Zhong; Li, Bing; Liu, Li; Lv, Kangle

    2014-09-01

    Chemically modified bamboo (CMB) was utilized for removing methylene blue (MB) from aqueous media in the present study. The adsorbent was characterized by Fourier transform infrared (FTIR) spectra and elemental analysis, which confirms that carboxyl groups and diethylenetriamine were successfully introduced into the surface of bamboo. The effects of initial MB concentration (100-900mgL(-1)), contact time (15-315min), the pH of the solution (3-10), temperature (298-318K), adsorbent dosage (0.4-2.6gL(-1)) and salt concentration on the adsorption efficiency of CMB towards MB were investigated. It was found that the adsorption of MB in CMB fits Langmuir mode well, and the maximum adsorption capacity of CMB achieved 606mgg(-1) at 298K, which is much higher than those obtained from previously investigated bioadsorbents. The adsorption kinetics can be described by pseudo-second-order kinetic model, and the adsorption of MB on CMB was an exothermic process. The results of the present study suggest that CMB is an effective biosorbent for removal of organic pollutants from aqueous solutions. Copyright © 2014 Elsevier Ltd. All rights reserved.

  6. Chemically modified peptide scaffolds target the CFTR-associated ligand PDZ domain.

    Directory of Open Access Journals (Sweden)

    Jeanine F Amacher

    Full Text Available PDZ domains are protein-protein interaction modules that coordinate multiple signaling and trafficking pathways in the cell and that include active therapeutic targets for diseases such as cancer, cystic fibrosis, and addiction. Our previous work characterized a PDZ interaction that restricts the apical membrane half-life of the cystic fibrosis transmembrane conductance regulator (CFTR. Using iterative cycles of peptide-array and solution-binding analysis, we targeted the PDZ domain of the CFTR-Associated Ligand (CAL, and showed that an engineered peptide inhibitor rescues cell-surface expression of the most common CFTR disease mutation ΔF508. Here, we present a series of scaffolds containing chemically modifiable side chains at all non-motif positions along the CAL PDZ domain binding cleft. Concordant equilibrium dissociation constants were determined in parallel by fluorescence polarization, isothermal titration calorimetry, and surface plasmon resonance techniques, confirming robust affinity for each scaffold and revealing an enthalpically driven mode of inhibitor binding. Structural studies demonstrate a conserved binding mode for each peptide, opening the possibility of combinatorial modification. Finally, we diversified one of our peptide scaffolds with halogenated substituents that yielded modest increases in binding affinity. Overall, this work validates our approach and provides a stereochemical foundation for further CAL inhibitor design and screening.

  7. Chemically modified peptide scaffolds target the CFTR-associated ligand PDZ domain.

    Science.gov (United States)

    Amacher, Jeanine F; Zhao, Ruizhi; Spaller, Mark R; Madden, Dean R

    2014-01-01

    PDZ domains are protein-protein interaction modules that coordinate multiple signaling and trafficking pathways in the cell and that include active therapeutic targets for diseases such as cancer, cystic fibrosis, and addiction. Our previous work characterized a PDZ interaction that restricts the apical membrane half-life of the cystic fibrosis transmembrane conductance regulator (CFTR). Using iterative cycles of peptide-array and solution-binding analysis, we targeted the PDZ domain of the CFTR-Associated Ligand (CAL), and showed that an engineered peptide inhibitor rescues cell-surface expression of the most common CFTR disease mutation ΔF508. Here, we present a series of scaffolds containing chemically modifiable side chains at all non-motif positions along the CAL PDZ domain binding cleft. Concordant equilibrium dissociation constants were determined in parallel by fluorescence polarization, isothermal titration calorimetry, and surface plasmon resonance techniques, confirming robust affinity for each scaffold and revealing an enthalpically driven mode of inhibitor binding. Structural studies demonstrate a conserved binding mode for each peptide, opening the possibility of combinatorial modification. Finally, we diversified one of our peptide scaffolds with halogenated substituents that yielded modest increases in binding affinity. Overall, this work validates our approach and provides a stereochemical foundation for further CAL inhibitor design and screening.

  8. Chemically modified tetracyclines: Novel therapeutic agents in the management of chronic periodontitis

    Directory of Open Access Journals (Sweden)

    Rupali Agnihotri

    2012-01-01

    Full Text Available Chronic periodontitis is a complex infection initiated by gram-negative bacteria which destroy the supporting structures of the tooth. Recently, it has been recognized that it is the host response to bacterial infection which causes greater destruction of the connective tissue elements, periodontal ligament and alveolar bone in periodontitis. This has led to the development of various host modulating approaches to target cells and their destructive mediators involved in tissue degradation. Chemically modified tetracyclines (CMTs are derivatives of tetracycline group of drugs which lack antimicrobial action but have potent host modulating affects. They inhibit pathologically elevated matrix metal loproteinases, pro-inflammtory cytokines and other destructive mediators. Bone resorption is also suppressed due to their combined anti-proteinase and apoptotic affects on osteoblasts and osteoclasts, respectively. Development of resistant bacteria and gastrointestinal toxicity seen with parent tetracyclines is not produced by CMTs. Hence, CMTs are viewed as potential therapeutic agents in the management of chronic diseases like periodontitis that involve destruction of connective tissue and bone.

  9. Effects of Zn Content on Crystal Structure, Cytocompatibility, Antibacterial Activity, and Chemical Stability in Zn-Modified Calcium Silicate Coatings

    Science.gov (United States)

    Li, Kai; Yu, Jiangming; Xie, Youtao; Huang, Liping; Ye, Xiaojian; Zheng, Xuebin

    2013-08-01

    In our previous study, Zn-modified calcium silicate coatings possess not only excellent chemical stability but also well antibacterial activity. Still, effects of zinc content on these properties and cytocompatibility remain unclear. In this paper, two kinds of Zn-modified calcium silicate coatings (ZC0.3, ZC0.5) were fabricated on Ti-6Al-4V substrates via plasma spraying technology. X-ray diffraction results and transmission electron microscopy observations showed that the ZC0.5 coating was composed of pure hardystonite (Ca2ZnSi2O7) phase, while, besides Ca2ZnSi2O7 phase, the amorphous CaSiO3 phase was also detected in the ZC0.3 coating. Chemical stability in Tris-HCl buffer solution and antibacterial activity of the Zn-modified calcium silicate coatings increased with an increase in zinc content. In vitro cytocompatibility evaluation demonstrated that the proliferation and alkaline phosphatase activity and collagen type I (COLI) secretion of osteoblast-like MC3T3-E1 cells on Zn-modified coatings were significantly enhanced compared to the Zn-free coating and Ti-6Al-4V control, and no cytotoxicity appeared on Zn-modified coatings. The better antibacterial activity and the enhanced capability to promote MC3T3-E1 cells differentiation of Zn-modified coatings should be attributed to the slow and constant Zn2+ releasing from the coatings.

  10. Vulnerability assessment of chemical industry facilities in South Korea based on the chemical accident history

    Science.gov (United States)

    Heo, S.; Lee, W. K.; Jong-Ryeul, S.; Kim, M. I.

    2016-12-01

    The use of chemical compounds are keep increasing because of their use in manufacturing industry. Chemical accident is growing as the consequence of the chemical use increment. Devastating damages from chemical accidents are far enough to aware people's cautious about the risk of the chemical accident. In South Korea, Gumi Hydrofluoric acid leaking accident triggered the importance of risk management and emphasized the preventing the accident over the damage reducing process after the accident occurs. Gumi accident encouraged the government data base construction relate to the chemical accident. As the result of this effort Chemical Safety-Clearing-house (CSC) have started to record the chemical accident information and damages according to the Harmful Chemical Substance Control Act (HCSC). CSC provide details information about the chemical accidents from 2002 to present. The detail informations are including title of company, address, business type, accident dates, accident types, accident chemical compounds, human damages inside of the chemical industry facilities, human damage outside of the chemical industry facilities, financial damages inside of the chemical industry facilities, and financial damages outside of the chemical industry facilities, environmental damages and response to the chemical accident. Collected the chemical accident history of South Korea from 2002 to 2015 and provide the spatial information to the each accident records based on their address. With the spatial information, compute the data on ArcGIS for the spatial-temporal analysis. The spatial-temporal information of chemical accident is organized by the chemical accident types, damages, and damages on environment and conduct the spatial proximity with local community and environmental receptors. Find the chemical accident vulnerable area of South Korea from 2002 to 2015 and add the vulnerable area of total period to examine the historically vulnerable area from the chemical accident in

  11. Color-Based Image Retrieval Using Perceptually Modified Hausdorff Distance

    Directory of Open Access Journals (Sweden)

    Park BoGun

    2008-01-01

    Full Text Available In most content-based image retrieval systems, the color information is extensively used for its simplicity and generality. Due to its compactness in characterizing the global information, a uniform quantization of colors, or a histogram, has been the most commonly used color descriptor. However, a cluster-based representation, or a signature, has been proven to be more compact and theoretically sound than a histogram for increasing the discriminatory power and reducing the gap between human perception and computer-aided retrieval system. Despite of these advantages, only few papers have broached dissimilarity measure based on the cluster-based nonuniform quantization of colors. In this paper, we extract the perceptual representation of an original color image, a statistical signature by modifying general color signature, which consists of a set of points with statistical volume. Also we present a novel dissimilarity measure for a statistical signature called Perceptually Modified Hausdorff Distance (PMHD that is based on the Hausdorff distance. In the result, the proposed retrieval system views an image as a statistical signature, and uses the PMHD as the metric between statistical signatures. The precision versus recall results show that the proposed dissimilarity measure generally outperforms all other dissimilarity measures on an unmodified commercial image database.

  12. MODIFIED VIEW BASED APPROACHES FOR HANDWRITTEN TAMIL CHARACTER RECOGNITION

    Directory of Open Access Journals (Sweden)

    S. Sobhana Mari

    2015-08-01

    Full Text Available Finding simple and efficient features for offline hand written character recognition is still an active area of research. In this work, we propose modified view based feature extraction approaches for the recognition of handwritten Tamil characters. In the first approach, the five views of a normalized and binarized character image viz, top, bottom, left, right and front are extracted. Each view is then divided into 16 equal zones and the total numbers of background pixel in each zone are counted. The 80 values so obtained form a feature vector. In the second approach, the normalized and binaraized character images are divided into 16 equal zones. Five views are extracted from each zone and the total number of background pixel in each view is counted, resulting in 80 feature values. Further the above two approaches are modified by employing thinned images instead of the whole image. The extracted features are classified using SVM, MLP and ELM classifier. The discriminative powers of the proposed approaches are compared with that of four popular feature extraction approaches in character recognition. The feature extraction time and classification performances are also compared. The proposed modified approaches results in high classification performance (95.26% with comparatively less feature extraction time.

  13. Bio-based chemicals - green, but also sustainable?

    DEFF Research Database (Denmark)

    Ögmundarson, Ólafur; Herrgard, Markus; Förster, Jochen;

    For almost two decades, the chemical industry has put great effort into developing bio-chemicals,among others to fight global warming caused by greenhouse gas emissions, one of the biggest threats that are faced by our society today. To facilitate a growing and versatile bio-based chemical...... production, the US Department of Energy proposed in 2004 a list of 12 building block chemicals which can either be converged through biological or chemical conversions. Moving toward more bio-based chemicals, the chemical industry does not only claim to reduce climate change impacts, but also...... that they are increasing overall sustainability in chemical production. Whether such claims are justifiable is unclear. When sustainability of bio-based polymer production is assessed, various environmental trade-offs occur that need to be considered. It is not enough to claim that a bio-chemical is sustainable...

  14. Study of enzyme biosensor based on carbon nanotubes modified electrode for detection of pesticides residue

    Institute of Scientific and Technical Information of China (English)

    Shu Ping Zhang; Lian Gang Shan; Zhen Ran Tian; Yi Zheng; Li Yi Shi; Deng Song Zhang

    2008-01-01

    The paper describes a controllable layer-by-layer (LBL) self-assembly modification technique of multi-walled carbon nanotubes(MWNTs) and poly(diallyldimethylammonium chloride) (PDDA) towards glassy carbon electrode (GCE), Acetylcholinesterase(ACHE) was immobilized directly to the modified GCE by LBL self-assembly method, the activity value of AChE was detected byusing i-t technique based on the modified Ellman method. Then the composition of carbaryl were detected by the enzyme electrodewith 0.01U activity value and the detection limit of carbaryl is 10-12 g L-1 so the enzyme biosensor showed good properties forpesticides residue detection.2008 Shu Ping Zhang. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved.

  15. Modified Stancu operators based on inverse Polya Eggenberger distribution.

    Science.gov (United States)

    Deshwal, Sheetal; Agrawal, P N; Araci, Serkan

    2017-01-01

    In this paper, we construct a sequence of modified Stancu-Baskakov operators for a real valued function bounded on [Formula: see text], based on a function [Formula: see text]. This function [Formula: see text] is infinite times continuously differentiable on [Formula: see text] and satisfy the conditions [Formula: see text] and [Formula: see text] is bounded for all [Formula: see text]. We study the degree of approximation of these operators by means of the Peetre K-functional and the Ditzian-Totik modulus of smoothness. The quantitative Voronovskaja-type theorems are also established in terms of the first order Ditzian-Totik modulus of smoothness.

  16. The RSA Cryptoprocessor Hardware Implementation Based on Modified Montgomery Algorithm

    Institute of Scientific and Technical Information of China (English)

    CHEN Bo; WANG Xu; RONG Meng-tian

    2005-01-01

    RSA (Rivest-Shamir-Adleman)public-key cryptosystem is widely used in the information security area such as encryption and digital signature. Based on the modified Montgomery modular multiplication algorithm, a new architecture using CSA(carry save adder)was presented to implement modular multiplication. Compared with the popular modular multiplication algorithms using two CSA, the presented algorithm uses only one CSA, so it can improve the time efficiency of RSA cryptoprocessor and save about half of hardware resources for modular multiplication. With the increase of encryption data size n, the clock cycles for the encryption procedure reduce in T(n2) , compared with the modular multiplication algorithms using two CSA.

  17. Minimal incision surgery in strabismus: Modified fornix-based approach.

    Science.gov (United States)

    Pérez-Flores, I

    2016-07-01

    To evaluate the modified fornix-based technique as an approach for minimal incision surgery in strabismus. The medical records of all consecutive patients that underwent strabismus surgery with fornix-based conjunctival incision between 2007 and 2012 were retrospectively reviewed. As a primary variable, an analysis was made of the wound size depending on the number of stitches. A descriptive study was performed on the variables related to patients and to the type of strabismus and surgery. Out of 153patients identified, 138 with 294 surgeries were included. In 200 (68%) interventions, the incision was sutured with one stitch, in 77 (26.2%) with 2, in 13 (4.4%) with 3, and in 4 (1.4%) with 4, with the mean number of stitches being 1.39±0.64. The mean age of the patients was 39years (2-80), and 36 (26.1%) had previous strabismus surgery, with topical anaesthesia being used in 35 (25.4%) cases. At 3months after surgery deviation was ≤10DP in 114 (82.6%) patients. There were no wound-related complications. The modified fornix-based technique is an effective and safe approach for minimal incision surgery in strabismus, in patients at all ages, with previous history of strabismus surgery and with topical anaesthesia. Copyright © 2015 Sociedad Española de Oftalmología. Published by Elsevier España, S.L.U. All rights reserved.

  18. Evaluation of alkyne-modified isoprenoids as chemical reporters of protein prenylation.

    Science.gov (United States)

    DeGraw, Amanda J; Palsuledesai, Charuta; Ochocki, Joshua D; Dozier, Jonathan K; Lenevich, Stepan; Rashidian, Mohammad; Distefano, Mark D

    2010-12-01

    Protein prenyltransferases catalyze the attachment of C15 (farnesyl) and C20 (geranylgeranyl) groups to proteins at specific sequences localized at or near the C-termini of specific proteins. Determination of the specific protein prenyltransferase substrates affected by the inhibition of these enzymes is critical for enhancing knowledge of the mechanism of such potential drugs. Here, we investigate the utility of alkyne-containing isoprenoid analogs for chemical proteomics experiments by showing that these compounds readily penetrate mammalian cells in culture and become incorporated into proteins that are normally prenylated. Derivatization via Cu(I) catalyzed click reaction with a fluorescent azide reagent allows the proteins to be visualized and their relative levels to be analyzed. Simultaneous treatment of cells with these probes and inhibitors of prenylation reveals decreases in the levels of some but not all of the labeled proteins. Two-dimensional electrophoretic separation of these labeled proteins followed by mass spectrometric analysis allowed several labeled proteins to be unambiguously identified. Docking experiments and density functional theory calculations suggest that the substrate specificity of protein farnesyl transferase may vary depending on whether azide- or alkyne-based isoprenoid analogs is employed. These results demonstrate the utility of alkyne-containing analogs for chemical proteomic applications.

  19. Modifying ability of titanium-based pelleted master alloys

    Science.gov (United States)

    Bazhin, V. Yu.; Savchenkov, S. A.; Kosov, Ya. I.

    2017-05-01

    The problem of enhancing the quality of pressed titanium master alloys is discussed to increase the rate and degree of dissolution of their components and to ensure the formation of a fine-grained structure in aluminum alloys. A technology of producing a pelleted titanium master alloy for effective correction of the chemical composition of an aluminum alloy in casting is developed and tested. Incoming inspection of the component composition and the flux distribution in the volume of pressed pellets of various manufacturers is performed. The rate of dissolution of pressed powder master alloys in the aluminum melt is studied, and their modifying ability is estimated after studying the microstructures of cast blanks. Molasses is used as a binder in a pelleted master alloy. As a result, we achieved a uniform flux distribution over the pellet volume and the formation of uniform pores after annealing as compared pelleted master alloys of other manufacturers. The fabricated alloying briquettes have higher strength characteristics and their dissolution rate in the aluminum melt is higher than those of analogs by 15-20%.

  20. Cobalt as chemical modifier to improve chromium sensitivity and minimize matrix effects in tungsten coil atomic emission spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Silva, Sidnei G. [Group of Applied Instrumental Analysis, Department of Chemistry, Federal University of São Carlos, P.O. Box 676, São Carlos, SP 13560-970 (Brazil); Donati, George L., E-mail: georgedonati@yahoo.com.br [Department of Chemistry, Wake Forest University, Winston-Salem, NC 27109 (United States); Santos, Luana N. [Group of Applied Instrumental Analysis, Department of Chemistry, Federal University of São Carlos, P.O. Box 676, São Carlos, SP 13560-970 (Brazil); Jones, Bradley T. [Department of Chemistry, Wake Forest University, Winston-Salem, NC 27109 (United States); Nóbrega, Joaquim A. [Group of Applied Instrumental Analysis, Department of Chemistry, Federal University of São Carlos, P.O. Box 676, São Carlos, SP 13560-970 (Brazil)

    2013-05-30

    Graphical abstract: -- Highlights: •Charge transfer reactions increase the population of Cr{sup +}. •Chromium ions and electrons recombine to form excited-state Cr atoms. •A 10-fold improvement in LOD is observed for Cr emission measurements. •The two-step ionization/excitation mechanism improves sensitivity and accuracy. •High concentrations of Co also minimize matrix effects. -- Abstract: Cobalt is used as chemical modifier to improve sensitivity and minimize matrix effects in Cr determinations by tungsten coil atomic emission spectrometry (WCAES). The atomizer is a tungsten filament extracted from microscope light bulbs. A solid-state power supply and a handheld CCD-based spectrometer are also used in the instrumental setup. In the presence of 1000 mg L{sup −1} Co, WCAES limit of detection for Cr (λ = 425.4 nm) is calculated as 0.070 mg L{sup −1}; a 10-fold improvement compared to determinations without Co modifier. The mechanism involved in such signal enhancement is similar to the one observed in ICP OES and ICP-MS determinations of As and Se in the presence of C. Cobalt increases the population of Cr{sup +} by charge transfer reactions. In a second step, Cr{sup +}/e{sup −} recombination takes place, which results in a larger population of excited-state Cr atoms. This alternative excitation route is energetically more efficient than heat transfer from atomizer and gas phase to analyte atoms. A linear dynamic range of 0.25–10 mg L{sup −1} and repeatability of 3.8% (RSD, n = 10) for a 2.0 mg L{sup −1} Cr solution are obtained with this strategy. The modifier high concentration also contributes to improving accuracy due to a matrix-matching effect. The method was applied to a certified reference material of Dogfish Muscle (DORM-2) and no statistically significant difference was observed between determined and certified Cr values at a 95% confidence level. Spike experiments with bottled water samples resulted in recoveries between 93% and

  1. Effects of modified atmosphere and vacuum packaging on microbiological and chemical properties of rainbow trout (Oncorynchus mykiss) fillets.

    Science.gov (United States)

    Arashisar, Sükriye; Hisar, Olcay; Kaya, Mükerrem; Yanik, Telat

    2004-12-15

    Microbial (psychrotrophic, mesophilic aerobic bacteria and Enterobacteriacae counts), and chemical analysis [pH, total volatile bases nitrogen (TVB-N), lipid oxidation (Thiobarbituric acid reactive substance, TBARS)] of rainbow trout (Oncorynchus mykiss) fillets in air (control), vacuum and modified atmosphere packaging (MAP) with various gas mixtures conditions at 4+/-1 degrees C were determined. The gas mixtures evaluated were 100% CO2, 2.5% O2+7.5% N2+90% CO2 and 30% O2+30% N2+40% CO2. Psychrotrophic bacteria count was above 1 x 10(7) cfu/g on the 12th day in 100% CO2. However; mesophilic bacteria count was below 1 x 10(6) cfu/g at the end of the 14-day storage period. Enterobacteriaceae count was significantly lower in samples packaged with MAP. Lipid oxidation increased rapidly after 6 days of storage in the samples containing 30% O2. While minimum TBARS values were recorded in fillets containing 100% CO2 and vacuumed fillets, the lowest TVB-N values were obtained in fillets with 100% CO2.

  2. Effect of chemically modified silicas on the properties of hybrid gel electrolyte for Li-ion batteries

    Science.gov (United States)

    Walkowiak, Mariusz; Zalewska, Aldona; Jesionowski, Teofil; Waszak, Daniel; Czajka, Bogdan

    The aim of the presented work was to perform a preliminary study the physico-chemical properties of hybrid organic-inorganic gel electrolytes for Li-ion batteries based on the PVdF-HFP polymeric matrix and surface modified fumed silicas. Modifications were done by means of the so-called dry method using seven different silanes differing in the nature of the principal functional group: N-2-(aminoethyl)-3-amino propyltrimethoxysilane, 3-glycidoxypropyltrimetoxysilane, 3-mercaptopropyltrimetoxysilane, n-octyltriethoxysilane, 3-(chloropropyl)trimethoxysilane, 3-methacryloxypropyltrimetoxysilane, vinyltrimethoxysilane. The PVdF-HFP gels were prepared according to the so-called Bellcore process (two-step method). Impact of the silicas surface functionality on the degree of crystallinity of the polymeric membranes was studied using the differential scanning calorimetry technique. Applicability of the prepared gel electrolytes for the Li-ion technology was estimated on the basis of specific conductivity measurements. It was shown that modification of the silica surface by most of the silanes causes an increase in the gel specific conductivity by about two orders of magnitude as compared to gel with unmodified silica.

  3. Effect of chemically modified silicas on the properties of hybrid gel electrolyte for Li-ion batteries

    Energy Technology Data Exchange (ETDEWEB)

    Walkowiak, Mariusz; Waszak, Daniel; Czajka, Bogdan [Central Laboratory of Batteries and Cells, ul. Forteczna 12, 61-362 Poznan (Poland); Zalewska, Aldona [Warsaw University of Technology, Department of Chemistry, ul. Noakowskiego 3, 00-664 Warsaw (Poland); Jesionowski, Teofil [Poznan University of Technology, Institute of Chemical Technology and Engineering, Pl. Marii Sklodowskiej-Curie 2, 60-965 Poznan (Poland)

    2006-09-13

    The aim of the presented work was to perform a preliminary study the physico-chemical properties of hybrid organic-inorganic gel electrolytes for Li-ion batteries based on the PVdF-HFP polymeric matrix and surface modified fumed silicas. Modifications were done by means of the so-called dry method using seven different silanes differing in the nature of the principal functional group: N-2-(aminoethyl)-3-amino propyltrimethoxysilane, 3-glycidoxypropyltrimetoxysilane, 3-mercaptopropyltrimetoxysilane, n-octyltriethoxysilane, 3-(chloropropyl)trimethoxysilane, 3-methacryloxypropyltrimetoxysilane, vinyltrimethoxysilane. The PVdF-HFP gels were prepared according to the so-called Bellcore process (two-step method). Impact of the silicas surface functionality on the degree of crystallinity of the polymeric membranes was studied using the differential scanning calorimetry technique. Applicability of the prepared gel electrolytes for the Li-ion technology was estimated on the basis of specific conductivity measurements. It was shown that modification of the silica surface by most of the silanes causes an increase in the gel specific conductivity by about two orders of magnitude as compared to gel with unmodified silica. (author)

  4. Comparison of adsorption of Cd(II and Pb(II ions on pure and chemically modified fly ashes

    Directory of Open Access Journals (Sweden)

    Sočo Eleonora

    2016-06-01

    Full Text Available The study investigates chemical modifications of coal fly ash (FA treated with HCl or NH4HCO3 or NaOH or Na2edta, based on the research conducted to examine the behaviour of Cd(II and Pb(II ions adsorbed from water solution on treated fly ash. In laboratory tests, the equilibrium and kinetics were examined applying various temperatures (293 - 333 K and pH (2 - 11 values. The maximum Cd(II and Pb(II ions adsorption capacity obtained at 293 K, pH 9 and mixing time 2 h from the Langmuir model can be grouped in the following order: FA-NaOH > FA-NH4HCO3 > FA > FA-Na2edta > FA-HCl. The morphology of fly ash grains was examined via small-angle X-ray scattering (SAXS and images of scanning electron microscope (SEM. The adsorption kinetics data were well fitted by a pseudo-second-order rate model but showed a very poor fit for the pseudofirst order model. The intra-particle model also revealed that there are two separate stages in the sorption process, i.e. the external diffusion and the inter-particle diffusion. Thermodynamics parameters such as free energy, enthalpy and entropy were also determined. A laboratory test demonstrated that the modified coal fly ash worked well for the Cd(II and Pb(II ion uptake from polluted waters.

  5. Improved properties of chemically modified graphene/poly(methyl methacrylate nanocomposites via a facile in-situ bulk polymerization

    Directory of Open Access Journals (Sweden)

    X. Y. Yuan

    2012-10-01

    Full Text Available The nanosheet of graphene was chemically modified by long alkyl chain for enhanced compatibility with polymer matrix and graphene/poly(methyl methacrylate (PMMA nanocomposites with homogeneous dispersion of the nanosheets and enhanced nanofiller-matrix interfacial interaction were fabricated via a facile in-situ bulk polymerization. The nanocomposites were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, Scanning electron microscopy and thermogravimetry. The results showed that the graphene nanosheets were fully exfoliated in PMMA matrix and the thermal and mechanical properties of the nanocomposites were significantly improved at low graphene loadings. Large shifts of 15°C in the glass transition temperature and 27°C improvement of onset thermal degradation temperature were achieved with graphene loading as low as 0.07 wt%. A 67% increase in tensile strength was also observed by the addition of only 0.5 wt% graphene. The method used in this study provided a novel route to other graphene-based polymers.

  6. Study of the adsorption and electroadsorption process of Cu (II) ions within thermally and chemically modified activated carbon.

    Science.gov (United States)

    Macías-García, A; Gómez Corzo, M; Alfaro Domínguez, M; Alexandre Franco, M; Martínez Naharro, J

    2017-04-15

    The aim of this work is to modify the porous texture and superficial groups of a commercial activated carbon through chemical and thermal treatment and subsequently study the kinetics of adsorption and electroadsorption of Cu (II) ion for these carbons. Samples of three activated carbons were used. These were a commercial activated carbon, commercial activated carbon modified thermically (C-N2-900) and finally commercial activated carbon modified chemically C-SO2-H2S-200. The activated carbons were characterized chemically and texturally and the electrical conductivity of them determined. Different kinetic models were applied. The kinetics of the adsorption and electroadsorption process of the Cu (II) ion fits a pseudo second order model and the most likely mechanism takes place in two stages. A first step through transfer of the metal mass through the boundary layer of the adsorbent and distribution of the Cu (II) on the external surface of the activated carbon and a second step that represents intraparticle diffusion and joining of the Cu (II) with the active centres of the activated carbon. Finally, the kinetics of the adsorption process are faster than the kinetics of the electroadsorption but the percentage of the Cu (II) ion retained is much higher in the electroadsorption process.

  7. Effect of surface chemical composition on the work function of silicon substrates modified by binary self-assembled monolayers.

    Science.gov (United States)

    Kuo, Che-Hung; Liu, Chi-Ping; Lee, Szu-Hsian; Chang, Hsun-Yun; Lin, Wei-Chun; You, Yun-Wen; Liao, Hua-Yang; Shyue, Jing-Jong

    2011-09-07

    It has been shown that the application of self-assembled monolayers (SAMs) to semiconductors or metals may enhance the efficiency of optoelectronic devices by changing the surface properties and tuning the work functions at their interfaces. In this work, binary SAMs with various ratios of 3-aminopropyltrimethoxysilane (APTMS) and 3-mercaptopropyltrimethoxysilane (MPTMS) were used to modify the surface of Si to fine-tune the work function of Si to an arbitrary energy level. As an electron-donor, amine SAM (from APTMS) produced outward dipole moments, which led to a lower work function. Conversely, electron-accepting thiol SAM (from MPTMS) increased the work function. It was found that the work function of Si changed linearly with the chemical composition and increased with the concentration of thiol SAMs. Because dipoles of opposite directions cancelled each other out, homogeneously mixing them leads to a net dipole moment (hence the additional surface potential) between the extremes defined by each dipole and changes linearly with the chemical composition. As a result, the work function changed linearly with the chemical composition. Furthermore, the amine SAM possessed a stronger dipole than the thiol SAM. Therefore, the SAMs modified with APTMS showed a greater work function shift than did the SAMs modified with MPTMS.

  8. Adsorption behavior of Cu(II) and Co(II) using chemically modified marine algae.

    Science.gov (United States)

    Foroutan, Rauf; Esmaeili, Hossein; Abbasi, Mohsen; Rezakazemi, Mashallah; Mesbah, Mohammad

    2017-08-28

    In this study, brown algae-modified biomass Padina sanctae crucis was used for copper (Cu(II)) and cobalt (Co(II)) heavy metal ions adsorption in synthetic wastewater. The effects of solution pH and adsorption efficiency for Cu(II) and Co(II) removal from aqueous solutions were studied. In order to study the kinetic behavior of adsorption, pseudo-first-order, pseudo-second-order kinetic models, liquid film penetration, and Ritchie second-order models were used. The results showed that the pseudo-second-order kinetic model was able to describe adsorbent behavior in comparison to the other models. Moreover, in order to study adsorbent equilibrium behavior, Langmuir and Freundlich isothermal models were used. Based on the Langmuir model, the adsorption capacity of Co(II) and Cu(II) was determined and their values were 13.73 and 13.996 mg/g, respectively. It was shown that both metal ions adsorption process is favorable and adsorption is physical. In this research, thermodynamic parameters were also studied in order to determine Gibbs free energy for both metal ions which were negative, indicating that metal ions adsorption process is spontaneous and the degree of self-adsorption increases as temperature increases.

  9. The Compatibility of Hepatocytes with Chemically Modified Porous Silicon with Reference to In Vitro Biosensors

    Science.gov (United States)

    Alvarez, Sara D.; Derfus, Austin M.; Schwartz, Michael P.; Bhatia, Sangeeta N.; Sailor, Michael J.

    2008-01-01

    Porous Si is a nanostructured material that is of interest for molecular and cell-based biosensing, drug delivery, and tissue engineering applications. Surface chemistry is an important factor determining the stability of porous Si in aqueous media, its affinity for various biomolecular species, and its compatibility with tissues. In this study, the attachment and viability of a primary cell type to porous Si samples containing various surface chemistries is reported, and the ability of the porous Si films to retain their optical reflectivity properties relevant to molecular biosensing is assessed. Four chemical species grafted to the porous Si surface are studied: silicon oxide (via ozone oxidation), dodecyl (via hydrosilylation with dodecene), undecanoic acid (via hydrosilylation with undecylenic acid), and oligo(ethylene) glycol (via hydrosilylation with undecylenic acid followed by an oligo(ethylene) glycol coupling reaction). Fourier Transform Infrared (FTIR) spectroscopy and contact angle measurements are used to characterize the surface. Adhesion and short-term viability of primary rat hepatocytes on these surfaces, with and without pre-adsorption of collagen type I, are assessed using vital dyes (calcein-AM and ethidium homodimer I). Cell viability on undecanoic acid-terminated porous Si, oxide-terminated porous Si, and oxide-terminated flat (non-porous) Si are monitored by quantification of albumin production over the course of 8 days. The stability of porous Si thin films after 8 days in cell culture is probed by measuring the optical interferometric reflectance spectra. Results show that hepatocytes adhere better to surfaces coated with collagen, and that chemical modification does not exert a deleterious effect on primary rat hepatocytes. The hydrosilylation chemistry greatly improves the stability of porous Si in contact with cultured primary cells while allowing cell coverage levels comparable to standard culture preparations on tissue culture

  10. Chemically modified carbon paste ion-selective electrodes for determination of atorvastatin calcium in pharmaceutical preparations

    Directory of Open Access Journals (Sweden)

    Salwa Fares Rassi

    2017-06-01

    Full Text Available A simple, rapid and sensitive method for the determination of atorvastatin calcium in pharmaceutical preparations using two modified carbon paste electrodes was developed. One electrode (sensor A is based on ion-pair of atorvastatin with 5,6-diaminouracil hydrochloride (ATS-DAUH and the other (sensor B is based on atorvastatin with picric acid (ATS-PC. Among three different solvent mediators tested, dioctylphthalate (DOPH exhibited a proper behavior including Nernstian slopes of the calibration curve at 58.76 ± 0.8 and 57.48±1 mV per decade for sensors A and B. The response times were 10 and 12 s, detection limits 1.3 × 10−6 and 2.2 × 10−6 M; the concentration range 2.5 × 10−6-7.9 × 10−2 M and 3.0 × 10−6 to 7.9 × 10−2 M respectively. The present electrodes show good discrimination of atorvastatin calcium from several inorganic, organic ions, sugars and some common excipients. The sensors were applied for the determination of atorvastatin calcium in pharmaceutical preparations using standard addition and the calibration curve methods. The results obtained were satisfactory with excellent percentage recovery comparable and sometimes better than those obtained by other routine methods for the assay. The proposed potentiometric methods offer the advantages of simplicity, accuracy, automation feasibility and applicability to turbid and colored sample solutions.

  11. Modified DM Models for Aging Networks Based on Neighborhood Connectivity

    Institute of Scientific and Technical Information of China (English)

    WEI Du-Qu; LIN Min; LUO Xiao-Shu; WANG Gang; ZOU Yan-Li; CHEN Tian-Lun

    2008-01-01

    Two modified Dorogovtsev-Mendes (DM) models of aging networks based on the dynamics of connecting nearest-neighbors are introduced. One edge of the new site is connected to the old site with probabilityekt-αas in the DM's model, where the degree and age of the old site are k and t, respectively. We consider two eases, I.e. The other edges of the new site attaching to the nearest-neighbors of the old site with uniform and degree connectivity probability, respectively. The network structure changes with an increase of aging exponent α. It is found that the networks can produce scale-free degree distributions with small-world properties. And the different connectivity probabilities lead to the different properties of the networks.

  12. Investigation of surface properties of physico-chemically modified natural fibres using inverse gas chromatography

    CSIR Research Space (South Africa)

    Cordeiro, N

    2011-01-01

    Full Text Available Inverse gas chromatography (IGC) is a suitable method to determine surface energy of natural fibres when compared to wetting techniques. In the present study, the surface properties of raw and modified lignocellulosic fibres have been investigated...

  13. HIGHLY EFFECTIVE CHEMICAL MODIFIERS FOR PRODUCTION OF CONCRETES WITH PRE-SET PROPERTIES

    OpenAIRE

    2012-01-01

    The paper demonstrates the application of industrial by-products and recycled materials. Waterproofing admixtures improve the structure and the properties of the cement stone. Development and preparation of highly effective waterproofing modifiers of durable effect, as well as development of the process procedure parameters, including mixing, activation, heat treatment, etc. are to be implemented. The composition of waterproofing modifiers is to be fine-tuned to synergize the behaviour of var...

  14. Development of GaN-based micro chemical sensor nodes

    Science.gov (United States)

    Son, Kyung-ah; Prokopuk, Nicholas; George, Thomas; Moon, Jeong S.

    2005-01-01

    Sensors based on III-N technology are gaining significant interest due to their potential for monolithic integration of RF transceivers and light sources and the capability of high temperature operations. We are developing a GaN-based micro chemical sensor node for remote detection of chemical toxins, and present electrical responses of AlGaN/GaN HEMT (High Electron Mobility Transistor) sensors to chemical toxins as well as other common gases.

  15. Physisorption of DNA molecules on chemically modified single-walled carbon nanotubes with and without sonication.

    Science.gov (United States)

    Umemura, Kazuo; Ishibashi, Yu; Oura, Shusuke

    2016-09-01

    We investigated the physisorption phenomenon of single-stranded DNA (ssDNA) molecules onto two types of commercially available chemically functionalized single-walled carbon nanotubes (SWNTs) by atomic force microscopy (AFM) and agarose gel electrophoresis. We found that DNA molecules can adsorb on the water-soluble SWNT surfaces without sonication, although sonication treatment has been used for hybridization of DNA and SWNTs in many previous studies. Using our method, damage of DNA molecules by sonication can be avoided. On the other hand, the amount of DNA molecules adsorbed on SWNT surfaces increased when the samples were sonicated. This fact suggests that the sonication is effective not only at debundling of SWNTs, but also at assisting DNA adsorption. Furthermore, DNA adsorption was affected by the types of functionalized SWNTs. In the case of SWNTs functionalized with polyethylene glycol (PEG-SWNT), physisorption of ssDNA molecules was confirmed only by agarose-gel electrophoresis. In contrast, amino-terminated SWNTs (NH2-SWNTs) showed a change in the height distribution profile based on AFM observations. These results suggest that DNA molecules tended to adsorb to NH2-SWNT surfaces, although DNA molecules can also adsorb on PEG-SWNT surfaces. Our results revealed fundamental information for developing nanobiodevices using hybrids of DNA and SWNTs.

  16. The investigation on sulfation of modified Ca-based sorbent

    Energy Technology Data Exchange (ETDEWEB)

    Hongwei Chen; Chunbo Wang; Yonghua Li; Zijie Wang [North China Electric Power University, Baoding (China). Department of Power Engineering

    2003-07-01

    The sulfation of a limestone modified by Na{sub 2}CO{sub 3} was investigated in this paper, which aimed to find the causes of its enhanced sulfation capacity. It was shown in the experiment that although the sulfur capture capability of M-CaO (the CaO calcined from modified limestone) is in excess of that of N-CaO (the CaO calcined from original sample), the specific surface area and porosity of the former are much less than that of the latter and also the average pore radius of the former become bigger. Based on the solid-state ion diffusion theory, a new mechanism to explain M-CaO sulfation is suggested. More lattice defects are formed in M-CaO, which reduce the resistance of ion diffusion in the CaSO{sub 4} product layer, and increase the Ca-conversion. To verify this, XRD was applied to measure the crystal structures of CaO samples. It was found M-CaO has bigger lattice distortion than N-CaO. It means that M-CaO has more lattice defects. In the sulfation the lattice defects in M-CaO will go into the CaSO{sub 4} product layer and it is that accelerates the ion diffusivity and leads to the higher Ca-conversion than that of N-CaO. By scanning the element distribution in reacted M-CaO using SEM, how the lattice defects formed in the product layers was verified.

  17. Cr(VI) adsorption from electroplating plating wastewater by chemically modified coir pith.

    Science.gov (United States)

    Suksabye, Parinda; Thiravetyan, Paitip

    2012-07-15

    Coir pith samples were chemically modified by grafting with acrylic acid for the removal of Cr(VI) from electroplating wastewater. The presence of acrylic acid on the coir pith surface was verified by a scanning electron microscope with an electron dispersive x-ray spectrometer (SEM/EDX), Fourier transform infrared spectroscopy (FTIR) and thermogravimetry (TG). The carbonyl groups (C==O) from the carboxylic acids (COOH) increased on the coir pith surface after grafting with acrylic acid. In addition, the thermal stability of the acrylic acid-grafted coir pith also improved. The optimum conditions for grafting the acrylic acid on the coir pith consisted of 2 M acrylic acid and 0.00125 M ceric ammonium nitrate (CAN, as an initiator). The maximum Cr(VI) removal (99.99 ± 0.07%) was obtained with the following conditions: a 1.3% (w/v) dosage of acrylic acid-grafted coir pith, a system pH of 2, a contact time of 22 h, a temperature of 30 °C, a particle size of <150 μm and an initial Cr(VI) of 1,171 mg l(-1). At system pH of 2, Cr(VI) in the HCrO(4)(-) form can be adsorbed with acrylic acid-grafted coir pith via an electrostatic attraction. The adsorption isotherm of 2 M acrylic acid-grafted coir pith exhibited a good fit with the Langmuir isotherm. The maximum Cr(VI) adsorption capacity of the 2 M acrylic acid-grafted coir pith was 196.00 mg Cr(VI) g(-1) adsorbent, whereas for coir pith without grafting, the maximum Cr(VI) removal was 165.00 mg Cr(VI) g(-1) adsorbent. The adsorption capacity of the acrylic acid-grafted coir pith for Cr(VI) was higher compared to the original coir pith. This result was due to the enhancement of the carbonyl groups on the coir pith surface that may have involved the mechanism of chromium adsorption. The X-ray absorption near edged structure (XANES) and desorption studies suggested that most of the Cr(III) that presented on the acrylic acid-grafted coir pith was due to the Cr(VI) being reduced to Cr(III) on the adsorbent surface. FTIR

  18. [Effects of Different Modifier Concentrations on Lead-Zinc Tolerance, Subcellular Distribution and Chemical Forms for Four Kinds of Woody Plants].

    Science.gov (United States)

    Chen, Yong-hua; Zhang, Fu-yun; Wu, Xiao-fu; Liang, Xi; Yuan, Si-wen

    2015-10-01

    Four kinds of lead-zinc tolerant woody plants: Nerium oleander, Koelreuteria paniculata, Paulownia and Boehmeria were used as materials to estimate their enrichment and transferable capacity of lead (Pb) and zinc (Zn) and analyze the subcellular distribution and chemical speciation of Zn and Ph in different parts of plants, under different modifier concentrations (CK group: 100% lead-zinc slag plus a small amount of phosphate fertilizer, improved one: 85% of lead-zinc slag ± 10% peat ± 5% bacterial manure plus a small amount of phosphate fertilizer, improved two: 75% lead-zinc slag ± 20% peat ± 5% bacterial manure ± a small amount of phosphate). Results showed that: (1) The content of Pb, Zn in matrix after planting four kinds of plants was lower than before, no significant difference between improved one and improved two of Nerium oleander and Boehmeria was found, but improved two was better than improved one of Paulownia, while improved one was better than improved two of Koelreuteria paniculata; Four plants had relatively low aboveground enrichment coefficient of Pb and Zn, but had a high transfer coefficient, showed that the appropriate modifier concentration was able to improve the Pb and Zn enrichment and transfer ability of plants. (2) In subcellular distribution, most of Pb and Zn were distributed in plant cell wall components and soluble components while the distribution in cell organelles such as mitochondria, chloroplasts and nucleus component were less. Compared with CK group, two improved group made soluble components of the cell walls of Pb fixation and retention of zinc role in the enhancement. (3) As for the chemical forms of Pb and Zn in plants, the main chemical forms of Pb were hydrochloric acid, sodium chloride and ethanol extractable forms, while other chemical form contents were few, the main chemical forms of Zn were different based on plant type. Compared with CK group, the proportion of the active Pb chemical form in different plant

  19. Graphene-Based Chemical Vapor Sensors for Electronic Nose Applications

    Science.gov (United States)

    Nallon, Eric C.

    chemiresistor device and used as a chemical sensor, where its resistance is temporarily modified while exposed to chemical compounds. The inherent, broad selective nature of graphene is demonstrated by testing a sensor against a diverse set of volatile organic compounds and also against a set of chemically similar compounds. The sensor exhibits excellent selectivity and is capable of achieving high classification accuracies. The kinetics of the sensor's response are further investigated revealing a relationship between the transient behavior of the response curve and physiochemical properties of the compounds, such as the molar mass and vapor pressure. This kinetic information is also shown to provide important information for further pattern recognition and classification, which is demonstrated by increased classification accuracy of very similar compounds. Covalent modification of the graphene surface is demonstrated by means of plasma treatment and free radical exchange, and sensing performance compared to an unmodified graphene sensor. Finally, the first example of a graphene-based, cross-reactive chemical sensor array is demonstrated by applying various polymers as coatings over an array of graphene sensors. The sensor array is tested against a variety of compounds, including the complex odor of Scotch whiskies, where it is capable of perfect classification of 10 Scotch whiskey variations.

  20. Stress-Strain of Hotmix Cold Laid Containing Buton Granular Asphat (BGA with Modifier Oil Base and Modifier Water Base as Wearing Course

    Directory of Open Access Journals (Sweden)

    Budiamin

    2015-07-01

    Full Text Available Buton granular asphalt (BGA is produced from natural rock asphalt. The employment of hotmix cold laid containing BGA with modifier oil base and modifier oil base can substitute hot rolled asphalt (HRA construction in the remote and distance areas. Natural rock asphalt that deposited in Buton Island, Southeast Sulawesi in Indonesia is crushed to produce Buton granular asphalt (BGA. BGA and cold modifier were utilized to produce hot mixture that can be laid at cold temperature of 50OC to 27OC.The present study provides the information concerning the stress-strain pattern and compressive strength of hotmix cold laid containing BGA and Modifier Oil Base and Modifier Water Base at the storing and compaction time of 4 hours, 3 days and 7 days.

  1. Electrochemical Biosensor Based on Boron-Doped Diamond Electrodes with Modified Surfaces

    Directory of Open Access Journals (Sweden)

    Yuan Yu

    2012-01-01

    Full Text Available Boron-doped diamond (BDD thin films, as one kind of electrode materials, are superior to conventional carbon-based materials including carbon paste, porous carbon, glassy carbon (GC, carbon nanotubes in terms of high stability, wide potential window, low background current, and good biocompatibility. Electrochemical biosensor based on BDD electrodes have attracted extensive interests due to the superior properties of BDD electrodes and the merits of biosensors, such as specificity, sensitivity, and fast response. Electrochemical reactions perform at the interface between electrolyte solutions and the electrodes surfaces, so the surface structures and properties of the BDD electrodes are important for electrochemical detection. In this paper, the recent advances of BDD electrodes with different surfaces including nanostructured surface and chemically modified surface, for the construction of various electrochemical biosensors, were described.

  2. Evaluation of modified nasal to oral endotracheal tube switch-For modified alar base cinching after maxillary orthognathic surgery.

    Science.gov (United States)

    Shaik, Taj Nizam Shakeel; Meka, Sridhar; Ch, Pavan Kumar; Kolli, Naga Neelima Devi; Chakravarthi, P Srinivas; Kattimani, Vivekanand S; L, Krishna Prasad

    2017-01-01

    Soft tissue changes secondary to Maxillary orthognathic surgery are many fold. The alar flare is one among them, which affects the appearance of the patient. Cinch suture has been used to prevent alar flare; but the presence of anaesthetic tube hinders cinching. So, the study was aimed to assess an efficacy of modified nasal to oral tube switch technique for modified alar cinching to prevent alar flare after orthognathic and nasal corrective surgeries. Patients were randomly allocated in each group, who underwent modified alar base cinching with and without nasal to oral tube switch. Changes in alar base width, upper lip length was measured with Digital Vernier Caliper and nasolabial angle (Cotg-Sn-Ls) on lateral cephalogram at 1st, 3rd, 6th, and 12th months after surgery. The time taken and ease of tube switch were noted. The data obtained were tabulated and interpreted using a test of significance. Study results showed no statistical significant difference in perinasal soft changes among both groups. But tube switch appears to be beneficial to prevent alar flare. Modified alar base cinching was performed effectively in patients with a modified tube switch technique. It increased positive results in comparison with non-shift. The technique of tube switch used is effective in prevention of alar flare. Because of small sample size and limited period of follow up, our study suggests multi centre, randomized studies to know the technical difficulties of tube switch for cinching and aesthetic results with varying anaesthetist and the surgeon's experience.

  3. Magnetorheological finishing with chemically modified fluids for studying material removal of single-crystal ZnS

    Science.gov (United States)

    Salzman, S.; Romanofsky, H. J.; Clara, Y. I.; Giannechini, L. J.; West, Garrett J.; Lambropoulos, J. C.; Jacobs, S. D.

    2013-09-01

    Magnetorheological finishing (MRF) of polycrystalline, chemical-vapor-deposited (CVD) zinc sulfide (ZnS) and zinc selenide (ZnSe) can leave millimeter-size artifacts on the part surface. These pebble-like features come from the anisotropic mechanical and chemical properties of the ceramic material and from the CVD growth process itself. The resulting surface texture limits the use of MRF for polishing aspheric and other complex shapes using these important infrared (IR) ceramics. An investigation of the individual contributions of chemistry and mechanics to polishing of other polycrystalline ceramics has been employed in the past to overcome similar material anisotropy problems. The approach taken was to study the removal process for the different single-crystal orientations that comprise the ceramic, making adjustments to mechanics (polishing abrasive type and concentration) and polishing slurry chemistry (primarily pH) to equalize the removal rate for all crystal orientations. Polishing with the modified slurry was shown to prevent the development of surface texture. Here we present mechanical (microhardness testing) and chemical (acid etching) studies performed on the four single-crystal orientations of ZnS: 100, 110, 111, and 311. We found that the (111) plane is 35% to 55% harder and 30% to 40% more resistant to chemical etching than the other three planes. This relatively high degree of variation in these properties can help to explain the surface texture developed from MRF of the polycrystalline material. Theoretical calculations of microhardness, planar, and bond densities are presented and compared with the experimental data. Here surface characterization of these single-crystal orientations of ZnS for material removal and roughness with chemically modified MR fluids at various pH levels between pH 4 and pH 6 are presented for the first time.

  4. Chemically Modified Starch; Allyl- and Epoxy-Starch Derivatives: Their Synthesis and Characterization

    NARCIS (Netherlands)

    Franssen, M.C.R.; Boeriu, C.

    2014-01-01

    Both native and modified starches, such as starch that is pregelatinized, extruded, acid-converted, cross-linked, and substituted, are widely used in industry. This chapter describes a mild two-step process for the synthesis of novel, highly reactive granular epoxy-starch derivatives. Via this metho

  5. Chemically Modified Starch; Allyl- and Epoxy-Starch Derivatives: Their Synthesis and Characterization

    NARCIS (Netherlands)

    Franssen, M.C.R.; Boeriu, C.

    2014-01-01

    Both native and modified starches, such as starch that is pregelatinized, extruded, acid-converted, cross-linked, and substituted, are widely used in industry. This chapter describes a mild two-step process for the synthesis of novel, highly reactive granular epoxy-starch derivatives. Via this metho

  6. High-affinity triplex targeting of double stranded DNA using chemically modified peptide nucleic acid oligomers

    DEFF Research Database (Denmark)

    Hansen, Mads E; Bentin, Thomas; Nielsen, Peter E

    2009-01-01

    While sequence-selective dsDNA targeting by triplex forming oligonucleotides has been studied extensively, only very little is known about the properties of PNA-dsDNA triplexes-mainly due to the competing invasion process. Here we show that when appropriately modified using pseudoisocytosine subs...

  7. Chemically Modified Starch; Allyl- and Epoxy-Starch Derivatives: Their Synthesis and Characterization

    NARCIS (Netherlands)

    Franssen, M.C.R.; Boeriu, C.

    2014-01-01

    Both native and modified starches, such as starch that is pregelatinized, extruded, acid-converted, cross-linked, and substituted, are widely used in industry. This chapter describes a mild two-step process for the synthesis of novel, highly reactive granular epoxy-starch derivatives. Via this

  8. Evaluation of a Modified ADC-Based Thermometry Bridge

    Science.gov (United States)

    Podgornik, T.; Batagelj, V.; Winkler, G.; Hartl, H.; Drnovsek, J.

    2011-12-01

    This article presents the modification and testing of an ADC-based thermometry bridge. The instrument under investigation is an Anton Paar MKT 50 Millikelvin Thermometer (developed at the IFE, TU-Graz) based on a precision analog-to-digital converter (ADC). During preliminary testing, it was found that the MKT 50 performs better than its declared uncertainty (1 mK equal to 1 ppm when using a 100 Ω PRT) and is comparable to thermometry resistance ratio bridges typically used in secondary thermometry laboratories (with typical uncertainties from 0.1 mK to 1 mK). The modifications to the original bridge were undertaken by the development team of the MKT 50 at the Graz University of Technology, Austria. Measurements and evaluation of the modified instruments were performed at the MIRS/UL-FE/LMK. For the MKT 50 to be used in thermometry laboratories as a reference unit, measuring parameters of the instrument had to be changed. During the first modification, the upper limit of the instrument range was decreased from 400 Ω to 133 Ω, this is a preferred range for standard platinum resistance thermometers (SPRTs). This also meant an increase in the measuring current from 0.5 mA to the more frequently used 1 mA. A modification of the programmable ADC control unit increased the resolution from 24 bit to 27 bit. By adding a switch, the use of an external standard resistor was enabled. After this stage of the modification, the first tests on the instrument were performed. The second stage was aimed at the removal of noise sources. The instrument was prepared in such a way that it only used two input channels, one connected to the SPRT and the other to the standard resistor. Also, the components of the ADC were upgraded to further reduce noise. The elimination of one input channel sped up measurements, making the PC software capable of taking several readings in a shorter time period. All tests were performed in laboratory conditions, where precision AC and DC resistance

  9. Bioprocessing of bio-based chemicals produced from lignocellulosic feedstocks.

    Science.gov (United States)

    Kawaguchi, Hideo; Hasunuma, Tomohisa; Ogino, Chiaki; Kondo, Akihiko

    2016-12-01

    The feedstocks used for the production of bio-based chemicals have recently expanded from edible sugars to inedible and more recalcitrant forms of lignocellulosic biomass. To produce bio-based chemicals from renewable polysaccharides, several bioprocessing approaches have been developed and include separate hydrolysis and fermentation (SHF), simultaneous saccharification and fermentation (SSF), and consolidated bioprocessing (CBP). In the last decade, SHF, SSF, and CBP have been used to generate macromolecules and aliphatic and aromatic compounds that are capable of serving as sustainable, drop-in substitutes for petroleum-based chemicals. The present review focuses on recent progress in the bioprocessing of microbially produced chemicals from renewable feedstocks, including starch and lignocellulosic biomass. In particular, the technological feasibility of bio-based chemical production is discussed in terms of the feedstocks and different bioprocessing approaches, including the consolidation of enzyme production, enzymatic hydrolysis of biomass, and fermentation.

  10. Biosorption of Cu (II onto chemically modified waste mycelium of Aspergillus awamori: Equilibrium, kinetics and modeling studies

    Directory of Open Access Journals (Sweden)

    ZDRAVKA VELKOVA

    2012-01-01

    Full Text Available The biosorption potential of chemically modified waste mycelium of industrial xylanase-producing strain Aspergillus awamori for Cu (II removal from aqueous solutions was evaluated. The influence of pH, contact time and initial Cu (II concentration on the removal efficiency was evaluated. Maximum biosorption capacity was reached by sodium hydroxide treated waste fungal mycelium at pH 5.0. The Langmuir adsorption equation matched very well the adsorption equilibrium data in the studied conditions. The process kinetic followed the pseudo-firs order model.

  11. Use of modified chemical route for ZnSe nanocrystalline thin films growth: Study on surface morphology and physical properties

    Science.gov (United States)

    Kale, R. B.; Lokhande, C. D.; Mane, R. S.; Han, Sung-Hwan

    2006-06-01

    The zinc selenide thin films have been deposited using modified chemical bath deposition (M-CBD) method. Zinc acetate and sodium selenosulphate were used as Zn 2+ and Se 2- ion sources, respectively. The preparative parameters such as concentration, pH, number of deposition cycles have been optimized in order to deposit ZnSe thin films. The as-deposited ZnSe thin films are specularly reflective and faint yellowish in color. The as-deposited ZnSe films are annealed in an air atmosphere at 473 K for 2 h. The films are characterized using structural, morphological, compositional, optical and electrical properties.

  12. Incorporating Student Input in Developing Alternate Assessments Based on Modified Academic Achievement Standards

    Science.gov (United States)

    Roach, Andrew T.; Beddow, Peter A.; Kurz, Alexander; Kettler, Ryan J.; Elliott, Stephen N.

    2010-01-01

    In developing alternate assessments based on modified academic achievement standards (AA-MAS), several states have modified existing test items with the aim of enhancing accessibility and reducing difficulty for students with disabilities. Using Grade 8 multiple-choice test items in unmodified and modified forms, two studies examined student…

  13. Incorporating Student Input in Developing Alternate Assessments Based on Modified Academic Achievement Standards

    Science.gov (United States)

    Roach, Andrew T.; Beddow, Peter A.; Kurz, Alexander; Kettler, Ryan J.; Elliott, Stephen N.

    2010-01-01

    In developing alternate assessments based on modified academic achievement standards (AA-MAS), several states have modified existing test items with the aim of enhancing accessibility and reducing difficulty for students with disabilities. Using Grade 8 multiple-choice test items in unmodified and modified forms, two studies examined student…

  14. Removal of Chlorinated Chemicals in H2 Feedstock Using Modified Activated Carbon

    Directory of Open Access Journals (Sweden)

    Prapaporn Luekittisup

    2015-01-01

    Full Text Available Activated carbon (GAC was impregnated by sodium and used as adsorbent to remove chlorinated hydrocarbon (CHC gases contaminated in H2 feedstock. The adsorption was carried out in a continuous packed-bed column under the weight hourly space velocity range of 0.8–1.0 hr−1. The adsorption capacity was evaluated via the breakthrough curves. This modified GAC potentially adsorbed HCl and VCM of 0.0681 gHCl/gadsorbent and 0.0026 gVCM/gadsorbent, respectively. It showed higher adsorption capacity than SiO2 and Al2O3 balls for both organic and inorganic CHCs removal. In addition, the kinetic adsorption of chlorinated hydrocarbons on modified GAC fit well with Yoon-Nelson model.

  15. Determination of vanadium in mussels by electrothermal atomic absorption spectrometry without chemical modifiers

    Energy Technology Data Exchange (ETDEWEB)

    Saavedra, Y.; Fernandez, P. [Centro de Control do Medio Marino, Peirao de Vilaxoan s/n, Vilagarcia de Arousa, 36611 Pontevedra (Spain); Gonzalez, A. [Departamento de Quimica Analitica, Nutricion y Bromatologia, Facultad de Quimica, 15706, Santiago de Compostela (Spain)

    2004-05-01

    A method was developed for the quantitative determination of total vanadium concentration in mussels via electrothermal atomic absorption spectrometry (ETAAS). After the microwave digestion of the samples, a program using temperatures of 1600 C and 2600 C for ashing and atomization respectively, without any matrix modifiers, allowed us to obtain results that were satisfactory since they agreed closely with certified reference material values. The detection limit was 0.03 mg kg{sup -1} (dry weight), indicating that the method is suitable for the analysis of mussel samples. This determination was compared with matrix modifiers that have been reported previously. The method was applied to various cultivated and wild mussels from the Galician coast, yielding levels below 1 mg kg{sup -1} (wet weight). (orig.)

  16. EXTENDING THE KNOWLEDGE BASE OF CHEMICAL ENGINEERING

    Institute of Scientific and Technical Information of China (English)

    Mooson Kwauk

    2005-01-01

    The obvious current reversion to micro-scale investigations in basic chemical engineering, combined with the need, of a quite different nature, in the rapid growth of high added-value and small-lot functional materials, have been pointing to an area not yet sufficiently covered by the unit operations, transport phenomena and chemical reaction engineering. Although it is difficult to define accurately this area, a cursory scan of the activities already in progress has revealed a few common attributes: multi-phased (structured), multi-scaled, multi-disciplined, nonlinear, needs for resolution to reductionism-solvable subsystems, and pervasive in the process industry. From these activities, the present paper drafts a tentative scheme for studying the related problems: first to dissect a problem into various scales - spatial, temporal or otherwise as best suits the case in hand- in order to identify pertinent parameters which are then organized into model formulations. Together with inter-scale model formulations, a zoom-in/zoom-out process is carried out between the scales, by trial-and-error and through reasoning, to arrive at a global formulation of a quantitative solution, in order to derive, eventually, the general from the particular.

  17. Rheological behaviour of polymer-modified bituminous mastics : a comparative analysis between physical and chemical modification

    OpenAIRE

    Shivokhin, Maxim; García Morales, Moisés; Partal López, Pedro; Cuadri Vega, Antonio Abad; Gallegos Montes, Críspulo

    2012-01-01

    Mastic, a bitumen/filler blend which naturally forms when bitumen is mixed with aggregates is the actual product used to bind coarse mineral particles in the asphalt mixtures. As a result, the characterisation of mastics is essential to improve the understanding of the response and performance of asphalt concrete pavements. On the other hand, the lack of experimental data concerning the behaviour of mastics and, above all, polymer-modified mastics has been lately claimed. In that sense, this ...

  18. Rheological behaviour of polymer-modified bituminous mastics : a comparative analysis between physical and chemical modification

    OpenAIRE

    Shivokhin, Maxim; García Morales, Moisés; Partal López, Pedro; Cuadri Vega, Antonio Abad; Gallegos Montes, Críspulo

    2012-01-01

    Mastic, a bitumen/filler blend which naturally forms when bitumen is mixed with aggregates is the actual product used to bind coarse mineral particles in the asphalt mixtures. As a result, the characterisation of mastics is essential to improve the understanding of the response and performance of asphalt concrete pavements. On the other hand, the lack of experimental data concerning the behaviour of mastics and, above all, polymer-modified mastics has been lately claimed. In that sense, this ...

  19. Influence of pyrolysis temperature on lead immobilization by chemically modified coconut fiber-derived biochars in aqueous environments.

    Science.gov (United States)

    Wu, Weidong; Li, Jianhong; Niazi, Nabeel Khan; Müller, Karin; Chu, Yingchao; Zhang, Lingling; Yuan, Guodong; Lu, Kouping; Song, Zhaoliang; Wang, Hailong

    2016-11-01

    Biochar has received widespread attention as an eco-friendly and efficient material for immobilization of toxic heavy metals in aqueous environments. In the present study, three types of coconut fiber-derived biochars were obtained by pyrolyzing at three temperatures, i.e., 300, 500, and 700 °C. In addition, nine types of biochars were prepared by chemical modification with ammonia, hydrogen peroxide, and nitric acid, respectively, which were used to investigate changes in physico-chemical properties by inter alia, Fourier transformation infrared spectrophotometry (FTIR), scanning electron microscope (SEM), and BET specific surface area analysis. Batch sorption experiments were carried out to determine the sorption capacity of the biochars for lead (Pb) in aqueous solutions. Results showed that the cation exchange capacity of biochar pyrolyzed at 300 °C and modified with nitric acid increased threefold compared to the control. Loosely corrugated carbon surface and uneven carbon surface of the biochar pyrolyzed at 300 °C were produced during ammonia and nitric acid modifications. Removal rate of Pb by the coconut biochar pyrolyzed at 300 °C and modified with ammonia was increased from 71.8 to 99.6 % compared to the untreated biochar in aqueous solutions containing 100 mg L(-1) Pb. However, chemical modification did not enhance adsorption of Pb of the biochars pyrolyzed at higher temperatures (e.g., 500 or 700 °C), indicating that resistance of biochars to chemical treatment increased with pyrolysis temperature.

  20. A small azide-modified thiazole-based reporter molecule for fluorescence and mass spectrometric detection

    Directory of Open Access Journals (Sweden)

    Stefanie Wolfram

    2014-10-01

    Full Text Available Molecular probes are widely used tools in chemical biology that allow tracing of bioactive metabolites and selective labeling of proteins and other biomacromolecules. A common structural motif for such probes consists of a reporter that can be attached by copper(I-catalyzed 1,2,3-triazole formation between terminal alkynes and azides to a reactive headgroup. Here we introduce the synthesis and application of the new thiazole-based, azide-tagged reporter 4-(3-azidopropoxy-5-(4-bromophenyl-2-(pyridin-2-ylthiazole for fluorescence, UV and mass spectrometry (MS detection. This small fluorescent reporter bears a bromine functionalization facilitating the automated data mining of electrospray ionization MS runs by monitoring for its characteristic isotope signature. We demonstrate the universal utility of the reporter for the detection of an alkyne-modified small molecule by LC–MS and for the visualization of a model protein by in-gel fluorescence. The novel probe advantageously compares with commercially available azide-modified fluorophores and a brominated one. The ease of synthesis, small size, stability, and the universal detection possibilities make it an ideal reporter for activity-based protein profiling and functional metabolic profiling.

  1. Predicting Drugs Side Effects Based on Chemical-Chemical Interactions and Protein-Chemical Interactions

    Directory of Open Access Journals (Sweden)

    Lei Chen

    2013-01-01

    Full Text Available A drug side effect is an undesirable effect which occurs in addition to the intended therapeutic effect of the drug. The unexpected side effects that many patients suffer from are the major causes of large-scale drug withdrawal. To address the problem, it is highly demanded by pharmaceutical industries to develop computational methods for predicting the side effects of drugs. In this study, a novel computational method was developed to predict the side effects of drug compounds by hybridizing the chemical-chemical and protein-chemical interactions. Compared to most of the previous works, our method can rank the potential side effects for any query drug according to their predicted level of risk. A training dataset and test datasets were constructed from the benchmark dataset that contains 835 drug compounds to evaluate the method. By a jackknife test on the training dataset, the 1st order prediction accuracy was 86.30%, while it was 89.16% on the test dataset. It is expected that the new method may become a useful tool for drug design, and that the findings obtained by hybridizing various interactions in a network system may provide useful insights for conducting in-depth pharmacological research as well, particularly at the level of systems biomedicine.

  2. Copyright Protection for Modifiable Digital Content Based on Distributed Environment

    Science.gov (United States)

    Park, Heejae; Kim, Jong

    Today, users themselves are becoming subjects of content creation. The fact that blog, wiki, and UCC have become very popular shows that users want to participate to create and modify digital content. Users who participate in composing content also want to have their copyrights on their modification parts. Thus, a copyright protection system for the content which can be modified by multiple users is required. However, the conventional DRM (Digital Rights Management) systems like OMA DRM are not suitable for the modifiable content because they do not support the content created and modified by different users. Therefore in this paper, we propose a new copyright protection system which allows each modifier of the content created and modified by multiple users to have one's own copyright. We propose data formats and protocols, and analyze the proposed system in terms of the correctness and security. Performance evaluation in the view of response time shows that the proposed system is 2 to 18 times shorter than other comparative schemes.

  3. [Research progress in chemical communication among insect-resistant genetically modified plants, insect pests and natural enemies].

    Science.gov (United States)

    Liu, Qing-Song; Li, Yun-He; Chen, Xiu-Ping; Peng, Yu-Fa

    2014-08-01

    Semiochemicals released by plants or insects play an important role in the communication among plants, phytophagous insects and their natural enemies. They thus form a chemical information network which regulates intra- and inter-specific behaviors and sustains the composition and structure of plant and insect communities. The application of insect-resistant genetically modified (IRGM) crops may affect the chemical communication within and among the tritrophic levels, and thus cause disturbances to the biotic community structure and the stability of the farmland ecosystem. This has raised concerns about the environmental safety of IRGM crops and triggered research worldwide. In the current article we provided a brief summary of the chemical communication among plants, herbivores and natural enemies; analyzed the potential of IRGM crops to affect the chemical communication between plants and arthropods and the related mechanisms; and discussed the current research progress and the future prospects in this field. We hope that this will promote the research in this field by Chinese scientists and increase our understanding of the potential effects of growing of IRGM crops on the arthropod community structure.

  4. A decision analytic approach to exposure-based chemical prioritization.

    Directory of Open Access Journals (Sweden)

    Jade Mitchell

    Full Text Available The manufacture of novel synthetic chemicals has increased in volume and variety, but often the environmental and health risks are not fully understood in terms of toxicity and, in particular, exposure. While efforts to assess risks have generally been effective when sufficient data are available, the hazard and exposure data necessary to assess risks adequately are unavailable for the vast majority of chemicals in commerce. The US Environmental Protection Agency has initiated the ExpoCast Program to develop tools for rapid chemical evaluation based on potential for exposure. In this context, a model is presented in which chemicals are evaluated based on inherent chemical properties and behaviorally-based usage characteristics over the chemical's life cycle. These criteria are assessed and integrated within a decision analytic framework, facilitating rapid assessment and prioritization for future targeted testing and systems modeling. A case study outlines the prioritization process using 51 chemicals. The results show a preliminary relative ranking of chemicals based on exposure potential. The strength of this approach is the ability to integrate relevant statistical and mechanistic data with expert judgment, allowing for an initial tier assessment that can further inform targeted testing and risk management strategies.

  5. Chemically modified fatty acid methyl esters: their potential for use as lubrication fluids and surfactants

    Science.gov (United States)

    A review of recent developments in the synthesis and characterization of lubrication fluids and surfactants from methyl oleate. The synthesis of materials made using an epoxidation route is the focus. This versatile method of chemical modification of fatty acid methyl esters improves their oxidati...

  6. Chemical and physical properties of Paulownia elongata biochar modified with oxidants for horticultural applications

    Science.gov (United States)

    Treatment of biochar with oxidants such as acids and hydrogen peroxide has been shown to alter porosity, increase adsorption of chemicals, and introduce functional groups on the biochar surfaces, all of which are desirable for their use in horticultural applications. Biochar was produced from the py...

  7. Construction of a Linux based chemical and biological information system.

    Science.gov (United States)

    Molnár, László; Vágó, István; Fehér, András

    2003-01-01

    A chemical and biological information system with a Web-based easy-to-use interface and corresponding databases has been developed. The constructed system incorporates all chemical, numerical and textual data related to the chemical compounds, including numerical biological screen results. Users can search the database by traditional textual/numerical and/or substructure or similarity queries through the web interface. To build our chemical database management system, we utilized existing IT components such as ORACLE or Tripos SYBYL for database management and Zope application server for the web interface. We chose Linux as the main platform, however, almost every component can be used under various operating systems.

  8. Chemical compound navigator: a web-based chem-BLAST, chemical taxonomy-based search engine for browsing compounds.

    Science.gov (United States)

    Prasanna, M D; Vondrasek, Jiri; Wlodawer, Alexander; Rodriguez, H; Bhat, T N

    2006-06-01

    A novel technique to annotate, query, and analyze chemical compounds has been developed and is illustrated by using the inhibitor data on HIV protease-inhibitor complexes. In this method, all chemical compounds are annotated in terms of standard chemical structural fragments. These standard fragments are defined by using criteria, such as chemical classification; structural, chemical, or functional groups; and commercial, scientific or common names or synonyms. These fragments are then organized into a data tree based on their chemical substructures. Search engines have been developed to use this data tree to enable query on inhibitors of HIV protease (http://xpdb.nist.gov/hivsdb/hivsdb.html). These search engines use a new novel technique, Chemical Block Layered Alignment of Substructure Technique (Chem-BLAST) to search on the fragments of an inhibitor to look for its chemical structural neighbors. This novel technique to annotate and query compounds lays the foundation for the use of the Semantic Web concept on chemical compounds to allow end users to group, sort, and search structural neighbors accurately and efficiently. During annotation, it enables the attachment of "meaning" (i.e., semantics) to data in a manner that far exceeds the current practice of associating "metadata" with data by creating a knowledge base (or ontology) associated with compounds. Intended users of the technique are the research community and pharmaceutical industry, for which it will provide a new tool to better identify novel chemical structural neighbors to aid drug discovery.

  9. Styromal based polymer films modified with copper microparticles

    Directory of Open Access Journals (Sweden)

    Viktor F. Vargalyuk

    2016-12-01

    Full Text Available A method for the synthesis of polymeric film based on a copolymer of styrene and maleic anhydride (stiromal and oligodiol was suggested. Block copolymer of ethylene glycol and propylene glycol was used as oligodiol. It was shown that synthesized materials have moderate water swelling capacity in and ion-exchange properties. Static exchange capacity in 0.1 mol/L NaOH aqueous solution is within the interval of 1.44–1.76 mmol/g. At air-dry state films have a tensile strength of 4–6.6 MPa and an elongation at break tensile 38–61 %. The effect of stiromal molecular weight and oligodiol type, and conditions of film formation on ion-exchange and physical-mechanical properties of the films was studied. The synthesized material appeared to be able to sorb Cu2+-ions from neutral and acidic solutions. The distribution coefficient in case of sorption from slightly acidic solution with Cu2+ concentration of 50 mg/L was 48–50. Composite material with a metal submicroparticles uniformly distributed in the polymeric matrix was obtained by chemical reduction of copper ions sorbed. It was found that the film acquires electric conductivity, as a result of filling of metal particles, which allows copper electrodeposition on the film surface.

  10. Chemical-potential-based Lattice Boltzmann Method for Nonideal Fluids

    CERN Document Server

    Wen, Binghai; He, Bing; Zhang, Chaoying; Fang, Haiping

    2016-01-01

    Chemical potential is an effective way to drive phase transition or express wettability. In this letter, we present a chemical-potential-based lattice Boltzmann model to simulate multiphase flows. The nonideal force is directly evaluated by a chemical potential. The model theoretically satisfies thermodynamics and Galilean invariance. The computational efficiency is improved owing to avoiding the calculation of pressure tensor. We have derived several chemical potentials of the popular equations of state from the free-energy density function. An effective chemical-potential boundary condition is implemented to investigate the wettability of a solid surface. Remarkably, the numerical results show that the contact angle can be linearly tuned by the surface chemical potential.

  11. Crystal engineering of energetic materials: co-crystals of Ethylenedinitramine (EDNA) with modified performance and improved chemical stability.

    Science.gov (United States)

    Aakeröy, Christer B; Wijethunga, Tharanga K; Desper, John

    2015-07-27

    In the area of energetic materials, co-crystallization is emerging as a new technology for modifying or enhancing the properties of existing energetic substances. Ethylenedinitramine (EDNA) is a known energetic material which requires attention partly due to its chemical instability originating with its two highly acidic protons. In order to stabilize EDNA, a co-crystallization approach targeting the acidic protons using a series of co-crystallizing agents with suitable hydrogen-bond acceptors was employed. Fifteen attempted co-crystallizations resulted in eight successful outcomes and six of these were crystallographically characterized and all showed evidence of hydrogen bonds to the intended protons. Calculated detonation properties and experimental thermal and impact data for the co-crystals were obtained and compared with those of pure EDNA. The co-crystal of EDNA and 1,2-bis(4-pyridyl)ethylene was recognized as a more thermally stable alternative to EDNA while the co-crystal of EDNA and pyrazine N,N'-dioxide showed comparable detonation strengths (and much improved chemical stability) compared with that of EDNA. The co-crystals EDNA:4,4'-bipyridine and EDNA:pyrazine N,N'-dioxide were found to be about 50 % less impact sensitive than EDNA, all of which illustrate how co-crystallizations can be utilized for successfully modifying specific aspects of energetic materials. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. Material removal mechanism of copper chemical mechanical polishing in a periodate-based slurry

    Science.gov (United States)

    Cheng, Jie; Wang, Tongqing; He, Yongyong; Lu, Xinchun

    2015-05-01

    The material removal mechanism of copper in a periodate-based slurry during barrier layer chemical mechanical polishing (CMP) has not been intensively investigated. This paper presents a study of the copper surface film chemistry and mechanics in a periodate-based slurry. On this basis, the controlling factor of the copper CMP material removal mechanism is proposed. The results show that the chemical and electrochemical reaction products on the copper surface are complex and vary considerably as a function of the solution pH. Under acidic conditions (pH 4) the copper surface underwent strong chemical dissolution while the corrosion was mild and uniform under alkaline conditions (pH 11). The corrosion effect was the lowest in near neutral solutions because the surface was covered with non-uniform Cu(IO3)2·H2O/Cu-periodate/copper oxides films, which had better passivation effect. The surface film thickness and mechanical removal properties were studied by AES and AFM nano-scratch tests. Based on the combined surface film analysis and CMP experiment results, it can be concluded that the controlling factor during copper CMP in a periodate-based slurry is the chemical-enhanced mechanical removal of the surface films. The periodate-based slurry should be modified by the addition of corrosion inhibitors and complexing agents to achieve a good copper surface quality with moderate chemical dissolution.

  13. Chemically Modified Chitosan Beads as Molecularly Imprinted Polymer Matrix for Adsorptive Separation of Proteins

    Institute of Scientific and Technical Information of China (English)

    Tian Ying GUO; Yong Qing XIA; Guang Jie HAO; Bang Hua ZHANG

    2004-01-01

    In a phosphate buffer, a hemoglobin (Hb)-imprinted polymer complex was prepared using maleic anhydride (MAH) modified chitosan beads as matrix, acrylamide (AM) as functional monomer, N,N-methylenebisacrylamide (MBA) as cross-linker and potassiumpersulfate (KPS)/sodium hydrogen sulfite (NaHSO3) as initiators. Langmuir analysis showed that an equal class of adsorption was formed in the molecular imprinting polymer (MIP), and the MIP has high adsorption capacity and selectivity for the imprinted molecule. The MIP can be reused and the recovery was approximately 100% at low concentration.

  14. Structure and Electrical Study of New Chemically Modified Poly(vinyl chloride

    Directory of Open Access Journals (Sweden)

    F. Ammari

    2015-01-01

    Full Text Available The aim of this work was to study the structural and electrical properties of a new polymer obtained by functionalization of a commercial poly(vinyl chloride (PVC (Mw = 48000 by grafting aminoalkyl and aminoaryl groups. Modified poly(vinyl chloride was prepared in two steps. The structural properties of the polymer were systematically investigated by varieties of techniques as differential scanning calorimetric (DSC, thermogravimetry analysis (TG, X-ray diffraction (XRD, and Fourier transform infrared (FTIR spectroscopy. The electrical properties of the polymer were studied by electrochemical impedance spectroscopy (EIS.

  15. Thermogravimetric Analysis of Modified Hematite by Methane (CH{sub 4}) for Chemical-Looping Combustion: A Global Kinetics Mechanism

    Energy Technology Data Exchange (ETDEWEB)

    Monazam, Esmail R; Breault, Ronald W; Siriwardane, Ranjani; Miller, Duane D

    2013-10-01

    Iron oxide (Fe{sub 2}O{sub 3}) or in its natural form (hematite) is a potential material to capture CO{sub 2} through the chemical-looping combustion (CLC) process. It is known that magnesium (Mg) is an effective methyl cleaving catalyst and as such it has been combined with hematite to assess any possible enhancement to the kinetic rate for the reduction of Fe{sub 2}O{sub 3} with methane. Therefore, in order to evaluate its effectiveness as a hematite additive, the behaviors of Mg-modified hematite samples (hematite –5% Mg(OH){sub 2}) have been analyzed with regard to assessing any enhancement to the kinetic rate process. The Mg-modified hematite was prepared by hydrothermal synthesis. The reactivity experiments were conducted in a thermogravimetric analyzer (TGA) using continuous stream of CH{sub 4} (5, 10, and 20%) at temperatures ranging from 700 to 825 {degrees}C over ten reduction cycles. The mass spectroscopy analysis of product gas indicated the presence of CO{sub 2}, H{sub 2}O, H{sub 2} and CO in the gaseous product. The kinetic data at reduction step obtained by isothermal experiments could be well fitted by two parallel rate equations. The modified hematite samples showed higher reactivity as compared to unmodified hematite samples during reduction at all investigated temperatures.

  16. Comparative repellent properties of certain chemicals against mosquitoes, house flies and cockroaches using modified techniques.

    Science.gov (United States)

    Vartak, P H; Tungikar, V B; Sharma, R N

    1994-09-01

    Several terpenoids were assessed for their repellent/toxic properties against mosquitoes (Aedes aegypti), house flies (Musca domestica) and cockroaches (Periplaneta americana). Impregnated wide mesh netting was used in the case of the Dipterans, while treated filtered paper was employed for the bioassays with cockroaches. Persistence of the repellent chemicals was studied. Doses ranged from 5-20 gm/M2 for the Dipterans and 25-100 mg per 4 x 4 cm filter paper for the cockroaches. Dimethyl phthalate (DMP) offered the maximum protection of the chemicals tested against mosquitoes but was not so effective against house flies and cockroaches. Citral and Eugenol were effective against all the three test insects. Other test compounds afforded varying degrees of protection. Application strategy and utility of the findings are discussed.

  17. Calcium phosphate formation from sea urchin - (brissus latecarinatus via modified mechano-chemical (ultrasonic conversion method

    Directory of Open Access Journals (Sweden)

    R. Samur

    2013-07-01

    Full Text Available This study aims to produce apatite structures, such as hydroxyapatite (HA and fluorapatite (FA, from precursor calcium phosphates of biological origin, namely from sea urchin, with mechano-chemical stirring and hot-plating conversion method. The produced materials were heat treated at 800 °C for 4 hours. X-ray diffraction and scanning electron microscopy (SEM studies were conducted. Calcium phosphate phases were developed. The SEM images showed the formation of micro to nano-powders. The experimental results suggest that sea urchin, Brissus latecarinatus skeleton could be an alternative source for the production of various mono or biphasic calcium phosphates with simple and economic mechano-chemical (ultrasonic conversion method.

  18. The optimal one dimensional periodic table: a modified Pettifor chemical scale from data mining

    Science.gov (United States)

    Glawe, Henning; Sanna, Antonio; Gross, E. K. U.; Marques, Miguel A. L.

    2016-09-01

    Starting from the experimental data contained in the inorganic crystal structure database, we use a statistical analysis to determine the likelihood that a chemical element A can be replaced by another B in a given structure. This information can be used to construct a matrix where each entry (A,B) is a measure of this likelihood. By ordering the rows and columns of this matrix in order to reduce its bandwidth, we construct a one-dimension ordering of the chemical elements, analogous to the famous Pettifor scale. The new scale shows large similarities with the one of Pettifor, but also striking differences, especially in what comes to the ordering of the non-metals.

  19. Calcium phosphate formation from sea urchin - (brissus latecarinatus) via modified mechano-chemical (ultrasonic) conversion method

    OpenAIRE

    R. Samur; Ozyegin, L.; D. Agaogullari; F. N. Oktar; Agathopoulos, S.; Kalkandelen, C.; I. Duman; B. Ben-Nissan

    2013-01-01

    This study aims to produce apatite structures, such as hydroxyapatite (HA) and fluorapatite (FA), from precursor calcium phosphates of biological origin, namely from sea urchin, with mechano-chemical stirring and hot-plating conversion method. The produced materials were heat treated at 800 °C for 4 hours. X-ray diffraction and scanning electron microscopy (SEM) studies were conducted. Calcium phosphate phases were developed. The SEM images showed the formation of micro to nano-powders. The e...

  20. Cellular RNA is chemically modified by exposure to air pollution mixtures.

    Science.gov (United States)

    Baldridge, Kevin C; Zavala, Jose; Surratt, Jason; Sexton, Kenneth G; Contreras, Lydia M

    2015-01-01

    RNAs are more susceptible to modifications than DNA, and chemical modifications in RNA have an effect on their structure and function. This study aimed to characterize chemical effects on total RNA in human A549 lung cells after exposure to elevated levels of major secondary air pollutants commonly found in urban locations, including ozone (O3), acrolein (ACR) and methacrolein (MACR). Enzyme-linked immunosorbent assays (ELISA) were used to measure levels of interleukin (IL)-8 in the growth media and 8-oxoguanine (8OG) levels in total cellular RNA, and lactate dehydrogenase (LDH) in the growth media was measured by a coupled enzymatic assay. Quantitative real-time polymerase chain reaction (qRT-PCR) was used to measure levels of microRNA 10b (miR-10b). The study found that 1-h exposure to all tested pollutant mixtures consistently caused significant increases in the levels of 8OG in total RNA. In the case of 4 ppm O3 exposures, measured levels of IL-8, LDH and miR-10b each showed consistent trends between two independent trials, but varied among these three targets. After 1-h exposures to an ACR+MACR mixture, measured levels of IL-8, LDH and miR-10b showed variable results. For mixtures of O3+ACR+MACR, IL-8 measurements showed no change; miR-10b and LDH showed variable results. The results indicate that short-term high-concentration exposures to air pollution can cause RNA chemical modifications. Chemical modifications in RNAs could represent more consistent markers of cellular stress relative to other inflammation markers, such as IL-8 and LDH, and provide a new biomarker endpoint for mechanistic studies in toxicity of air pollution exposure.

  1. Unconventional assembly of bimetallic Au-Ni janus nanoparticles on chemically modified silica spheres.

    Science.gov (United States)

    Jia, Lei; Pei, Xiaowei; Zhou, Feng; Liu, Weimin

    2014-02-10

    This paper reports that Janus Au-Ni nanoparticles (JANNPs) can self-assemble onto silica spheres in a novel way, which is different from that of single-component isotropic nanoparticles. JANNPs modified with octadecylamine (ODA) assemble onto catechol-modified silica spheres (SiO2-OH) to form a very special core-loop complex structure and finally the core-loop assemblies link each other to form large assemblies through capillary force and the hydrophobic interaction of the alkyl chains of ODA. The nanocomposites disassemble in the presence of vanillin and oleic acid because of the breakage of the catechol-metal link. Vanillin-induced disassembly enables the JANNPs to reassemble into a core-loop structure upon ODA addition. The assembly of SiO2-OH and isotropic Ni or Fe3O4 particles generates traditional core-satellite structures. This unconventional self-assembly can be attributed to the synergistic effect of Janus specificity and capillary force, which is also confirmed by the assembly of thiol-terminated silica spheres (SH-SiO2) with anisotropic JANNPs, isotropic Au, and Ni nanoparticles. These results can guide the development of novel composite materials using Janus nanoparticles as the primary building blocks. Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. A Systematic Methodology for Design of Emulsion Based Chemical Products

    DEFF Research Database (Denmark)

    Mattei, Michele; Kontogeorgis, Georgios; Gani, Rafiqul

    2012-01-01

    A systematic methodology for emulsion based chemical product design is presented. The methodology employs a model-based product synthesis/design stage and a modelexperiment based further refinement and/or validation stage. In this paper only the first stage is presented. The methodology employs...

  3. Chemical characterization of carbohydrate-based biosurfactants

    Science.gov (United States)

    High-yield, glycolipid-based biosurfactants are of increasing interest for use in environmentally benign cleaning or emulsifying agents. We have developed a MALDI-TOF/MS screen for the rapid analysis of several types of biosurfactants, including various acylated rhamnolipids in Pseudomonas extracts...

  4. POLYPROPYLENE-MODIFIED KAOLINITE COMPOSITES: EFFECT OF CHEMICAL MODIFICATION ON MECHANICAL, THERMAL AND MORPHOLOGICAL PROPERTIES

    Directory of Open Access Journals (Sweden)

    O. Meziane

    2016-05-01

    Full Text Available The intercalation of kaolinite with an ammonium salt was performed. Untreated and treated kaolinite samples were examined by XRD. PP/kaolinite compounds were prepared by the melt intercalation method. The effects of modified clay on properties of the prepared composites were studied. The XRD results showed that the treatment with the ammonium salt caused the return to the initial state of the clay. TGA thermograms marked an increase in thermal degradation of the composites, while the DSC results showed the decrease of the crystallization temperature and the melting point in presence of clay in the matrix owing to the fact that the filler acts as reinforcing effect. The mechanical properties of the composites exhibited important variations, the morphology of the composites was further studied using SEM and showed poor dispersion of used nanoclay in PP matrix.

  5. Physico-chemical characteristics of nano-organo bentonite prepared using different organo-modifiers

    Directory of Open Access Journals (Sweden)

    A.M. Motawie

    2014-09-01

    Full Text Available Different types of nano-organo bentonite (NOB were prepared from the Egyptian Bentonite (EB. EB was characterized by energy dispersive X-ray EDX. It was purified from different impurities using a conventional method via the treatment with HCl and distilled water. The modification of the clay was carried out using different types of organo-modifiers namely; hexadecyl trimethyl ammonium bromide (HTAB, 3-aminopropyltriethoxysilane (Silane, octadecylamine (ODA, and dodecylamine (DDA. The cation exchange capacity (CEC was measured for pristine bentonite after and before modification. The NB was characterized by FTIR, XRD, TEM, and TGA techniques. The obtained results indicated that variation of the interlayer space gallery was effected by the type of the penetrator used.

  6. UV Spectral Analysis of the Chemical Modification and Photolysis of Acetylacetone Modified Alumina Aqueous Solution

    Institute of Scientific and Technical Information of China (English)

    Chengbin JING; Xiujian ZHAO; Haizheng TAO; Xina WANG; Aiyun LIU

    2004-01-01

    Acetylacetone was firstly introduced into the aqueous media with the presence of aluminum sec-butoxide and peptizator. It was confirmed that the UV (ultraviolet) absorption band of acetylacetone underwent 14 nm of red-shift due to the formation of the six-membered ring of the complex between alumina and acetylacetone in the aqueous solution. It was also found that the chemical modification can be dissociated by the UV irradiation with a wavelength shorter than 286 nm as a result of the excitation of π-π* transition in the complex.

  7. Modifying culture conditions in chemical library screening identifies alternative inhibitors of mycobacteria.

    Science.gov (United States)

    Miller, Christopher H; Nisa, Shahista; Dempsey, Sandi; Jack, Cameron; O'Toole, Ronan

    2009-12-01

    In this study, application of a dual absorbance/fluorescence assay to a chemical library screen identified several previously unknown inhibitors of mycobacteria. In addition, growth conditions had a significant effect on the activity profile of the library. Some inhibitors such as Se-methylselenocysteine were detected only when screening was performed under nutrient-limited culture conditions as opposed to nutrient-rich culture conditions. We propose that multiple culture condition library screening is required for complete inhibitory profiling and for maximal antimycobacterial compound detection.

  8. Study on Natural and Modified Bentonite Adsorption of Antibiotics%Guangzhou Chemical Industry

    Institute of Scientific and Technical Information of China (English)

    刘希

    2016-01-01

    To deal with the water polluted by antibiotics, adsorption experiments for adsorption behavior of oxytetracycline and tetracycline on bentonite/acid modified bentonite were carried out to investigate the effect of pH,activation temperature, dosing quantity and adsorption time. The results showed that two kind of antibiotics could beabsorbed effectively when theactivation temperature was 200 ℃, pH=6 , the dosing quantity was 1 gandadsorption time was 8 h. Asakind of environmental friendlyadsorbent for promotion, modified bentonite is better than natural bentonite.%针对制药工业产生的抗生素废水,研究了一定条件下膨润土/酸改性膨润土对土霉素( OTC)和四环素( TC)的吸附作用,综合考察了原土与改性膨润土在不同pH、活化温度、投加量以及吸附时间等条件下的吸附效率。结果表明:在活化温度为200℃、 pH=6、投加量为1 g、吸附时间为8 h时,可以有效地吸附两种抗生素,且酸改性膨润土比膨润土吸附效果更好,能够作为环境友好的抗生素吸附剂进行推广。

  9. Investigation of the biofouling properties of several algae on different textured chemical modified silicone surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Jihai [Key Laboratory of Marine Materials and Related Technologies, Zhejiang Key Laboratory of Marine Materials and Protective Technologies, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo 315201 (China); University of Chinese Academy of Sciences, Beijing 100049 (China); Zhao, Wenjie, E-mail: zhaowj@nimte.ac.cn [Key Laboratory of Marine Materials and Related Technologies, Zhejiang Key Laboratory of Marine Materials and Protective Technologies, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo 315201 (China); Peng, Shusen; Zeng, Zhixiang; Zhang, Xin [Key Laboratory of Marine Materials and Related Technologies, Zhejiang Key Laboratory of Marine Materials and Protective Technologies, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo 315201 (China); Wu, Xuedong, E-mail: xdwu@nimte.ac.cn [Key Laboratory of Marine Materials and Related Technologies, Zhejiang Key Laboratory of Marine Materials and Protective Technologies, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo 315201 (China); Xue, Qunji [Key Laboratory of Marine Materials and Related Technologies, Zhejiang Key Laboratory of Marine Materials and Protective Technologies, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo 315201 (China)

    2014-08-30

    Highlights: • Engineered pillars, pits and grooves spaced 3–12 μm apart were fabricated on siloxane modified acrylic resin films. • The effect of feature size, geometry, and wettability on the settlement of different algae was evaluated. • The feature size and geometry displayed a substantial correlation with the antifouling properties. • A comparatively physical fouling deterrent mechanism was analyzed. - Abstract: Engineered pillars, pits and grooves spaced 3, 6, 9 and 12 μm apart were fabricated on siloxane modified acrylic resin films. The effect of feature size, geometry, and wettability on the settlement of different algae was evaluated. These films showed various antifouling performances to Ulothrix, Closterium and Navicula. For Navicula (length: 10–12 μm), the feature size and geometry displayed a substantial correlation with the antifouling properties. The film with pillars spaced 3 μm reduced Navicula settlement by 73% compared to the control surface. For Closterium (length: 45–55 μm), their responses were governed by the same underlying thermodynamic principles as wettability, the largest reduction in Closterium, 81%, was obtained on the surface with grooves spaced 12 μm apart. For Ulothrix (length: 5–8 mm), the surface also showed the best antifouling performance, the reduction ratio of the settlement on the surface with grooves spaced 12 μm apart could even reach 92%. At last, physical fouling deterrent mechanisms for the films with various textures were analyzed in detail. The feature size and geometry display a substantial correlation with the antifouling properties when the size of fouling algae is close to the textures. With the increasing size for algae, antifouling performance was getting better on surface with pillars or grooves because the algae are bridged between two or more features other than stabilizing its entire mass on one single feature or able to settle between features.

  10. Nile tilapia skin collagen sponge modified with chemical cross-linkers as a biomedical hemostatic material.

    Science.gov (United States)

    Sun, Leilei; Li, Bafang; Jiang, Dandan; Hou, Hu

    2017-07-26

    Nile tilapia skin collagen sponges were fabricated by freeze-drying technology and modified with 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide in the presence of N-hydroxysuccinimide (EDC/NHS), genipin+PBS, genipin+ethanol, tea polyphenol (TP), nordihydroguaiaretic acid (NDGA) and diphenyl phosphoryl azide (DPPA). Physicochemical and biological properties, micromorphology and compatibility before and after modification were investigated to evaluate collagen sponge as a hemostatic biomedical material. The mechanical property of collagen sponges strengthened after cross-linking. The elongation at break of cross-linked collagen sponges decreased except for EDC/NHS, which was close to that of non-crosslinked. The collagen sponge cross-linked with EDC/NHS exhibited the highest hygroscopicity in comparison with other cross-linkers. The resistance to collagenase biodegradation of collagen sponges after cross-linking strengthened significantly except for NDGA. Collagen sponges cross-linked with EDC/NHS, TP and NDGA maintained high porosity (97-98%), similar to non-crosslinked (98.42%). Collagen sponges could shorten the blood coagulation time. From the variations of the FTIR spectrum pattern and SEM, DPPA could change the secondary structure of collagen and destroy the spongy structure of collagen sponge, which was not suitable for the cross-linking of collagen sponge. Whereas, EDC/NHS was recognized as a perfect cross-linker owing to its excellent properties and porous microstructure. All fabricated collagen sponges were recognized to be biocompatible by the hemolysis assay in vitro. Therefore, collagen sponge modified with EDC/NHS could be used as a perfect biomedical hemostatic material. Copyright © 2017 Elsevier B.V. All rights reserved.

  11. Wrapping of a single bacterium with Functionalized - Chemically Modified Graphene (FCMG) sheets via highly specific protein-cell wall interaction

    Science.gov (United States)

    Mohanty, Nihar; Berry, Vikas

    2009-03-01

    Graphene has recently generated a lot of interest due to its unique structural and electrical properties. It's micro-scale area and sub-nano-scale thickness coupled with ballistic electronic transport at room temperature, low Johnston noise and low charge scattering, have made it a gold mine for novel applications. Since its discovery in 2004, there have been a plethora of studies on characterizing its unique physical, chemical and electrical properties of graphene as well as on integrating it with various physical/chemical systems to utilize these properties. But there have been limited or no studies on the integration of graphene with living microorganisms or mammalian cells. Here we describe the novel wrapping of a single live bacterium (Bacillus cereus) with a chemically modified graphene sheet functionalized with the protein Concanavalin-A (Con-A) via the highly specific Con-A - Teichoic acid interaction. We are investigating the structural and the electrical properties of these novel bacteria-FCMG ensembles. Further, we are also interested in characterizing this wrapping process in detail by studying the kinetics and the mechanism of action of bacterial-wrapping via 3D modelling. This is a first step towards the live-bio-nano-integration of graphene which would open up avenues for applications as diverse as bio-batteries using the Geobacter to recombinant enzyme compartmentalization.

  12. Phosphate adsorption using modified iron oxide-based sorbents

    Science.gov (United States)

    Phosphate RemovalThis dataset is associated with the following publication:Lalley , J., C. Han , G. RamMohan , T. Speth , J. Garland , M. Nadagouda , and D. Dionysiou. Phosphate Removal using Modified Bayoxide®E33 Adsorption Media. WATER RESEARCH. Elsevier Science Ltd, New York, NY, USA, issue}: 96-107, (2015).

  13. Surface modified Ti based metallic glasses for bioactivation by electrochemical treatment technique

    Energy Technology Data Exchange (ETDEWEB)

    Oak, Jeong-Jung, E-mail: ojj69@pusan.ac.kr [GCRC-SOP, Pusan Nat’l University, Busan (Korea, Republic of); Inoue, Akihisa [Institute for Materials Research, Tohoku University, Sendai (Japan); Rao, K. Venkat [Division of Engineering Materials Physics, KTH, Stockholm (Sweden); Chun, Ho-Hwan [Dept. of Naval Architecture and Ocean Engineering, Pusan Nat’l University, Busan (Korea, Republic of); Park, Yong Ho [Dept. of Materials Science and Engineering, Pusan Nat’l University, Busan (Korea, Republic of)

    2014-12-05

    The aim of this study is surface modification of Ni-free type Ti based metallic glass (Ti{sub 42}Hf{sub 11}Cu{sub 11}Pd{sub 36} at.%) for increasing calcification by electrochemical treatment. Ni-free type Ti based metallic glass has excellent mechanical and chemical properties which are comparable with those of Ti based alloys. Surface of Ti based metallic glasses was prepared as follows; one is anodically-oxidized porous layer by potentiostatic control in 5 M NaOH solution at 25 °C for 2 h, and the other is simple hydrothermal treated poros layer by immersion in 5 M NaOH solution at 60 °C for 24 h. The synthesized surface structures were characterized by X-ray diffraction (XRD) identification, SEM observation, energy dispersive X-ray spectroscopy (EDS) analysis and Auger electron spectroscopy (AES) analysis. These surfaces on the modified specimens have nano-mesh laminated structures and are consist of sodium titanate and titanium oxide. In addition, the above two types surfaces with nano-mesh laminated layer were immersed in Hank’s balance salt solution (HBSS) at 37 °C for 21 days for evaluation of calcification. The apatite-forming ability on these surfaces is observed by SEM observation and EDS analysis. As stated above surface modifications are also discussed about calcification effect by different surface treatment and different formability of porosity in this study. - Highlights: • Electrochemical treatment synthesizes nano-mesh laminated structures. • Large reticular area and fine nanopores are synthesized in alkali-solution at 25 °C. • Low crystal growth of sodium titanate densifies nano-mesh laminated structures. • The modified surface increases calcification in simulated body fluid.

  14. Isoindigo-based polymer photovoltaics: modifying polymer molecular structures to control the nanostructural packing motif.

    Science.gov (United States)

    Kim, Yu Jin; Lee, Yun-Ji; Kim, Yun-Hi; Park, Chan Eon

    2016-07-21

    Donor molecular structures, and their packing aspects in donor:acceptor active blends, play a crucial role in the photovoltaic performance of polymer solar cells. We systematically investigated a series of isoindigo-based donor polymers within the framework of a three-dimensional (3D) crystalline motif by modifying their chemical structures, thereby affecting device performances. Although our isoindigo-based polymer series contained polymers that differed only by their alkyl side chains and/or donating units, they showed quite different nanoscale morphological properties, which resulted in significantly different device efficiencies. Notably, blends of our isoindigo-based donor polymer systems with an acceptor compound, whereby the blends had more intermixed network morphologies and stronger face-on orientations of the polymer crystallites, provided better-performing photovoltaic devices. This behavior was analyzed using atomic force microscopy (AFM) and two-dimensional grazing incidence wide angle X-ray diffraction (2D-GIWAXD). To the best of our knowledge, no correlation has been reported previously between 3D nano-structural donor crystallites and device performances, particularly for isoindigo-based polymer systems.

  15. Timing of leaf removal modifies chemical and phenolic composition of Sauvignon Blanc wine

    Directory of Open Access Journals (Sweden)

    Wurz Douglas André

    2017-01-01

    Full Text Available The objective of this work was to evaluate the effect of different defoliation times on the chemical and phenolic composition of Sauvignon Blanc wine in high altitude regions of Santa Catarina - Brazil. The experiment was conducted in the 2015 and 2016 seasons, in a vineyard located in the city of São Joaquim – Santa Catarina State. The defoliation was carried out during phenological stages: full bloom, berries pepper-corn size, pea-sized berries, veraison, 15 days after veraison and control without leaf removal. During harvest, severity of Botrytis cinerea was assessed by visual evaluation through a diagrammatic scale. For the wine samples from each season, total acidity (meq L−1, pH, total polyphenol content (mg L−1 of gallic acid and color (Abs 420nm were performed. For the wines of the 2015 harvest, phenolic compounds were analyzed: gallic acid, catechin, vanillic acid, P-coumaric acid and rutin. The chemical composition of Sauvignon Blanc wine was affected as a result of leaf removal timing, defoliation carried out in full bloom, berries pepper-corn size and pea-sized berries reduced total acidity and increased pH of the wines in both seasons. For wine color, in both seasons, it was found a greater yellow coloration in wines originated from grapes where the plants were not defoliated. The increase of yellow coloration is due to the oxidation of catechins and epicatechins, which is related to the increase of botrytis bunch rot. In the 2015 season there were no influence of leaf removal timing in total polyphenols, however, in the 2016, the defoliation performed in full bloom resulted in lower polyphenols contents. Wines from non-defoliated plants presented higher values of catechin, rutin, P-coumaric acid and gallic acid, related to yellow coloration of wines and greater susceptibility to darkening and oxidation. For vanillic acid, wines from non-defoliated plants have the lowest values, this compound is important in wine preservation

  16. Facile synthesis of graphene oxide-modified lithium hydroxide for low-temperature chemical heat storage

    Science.gov (United States)

    Yang, Xixian; Huang, Hongyu; Wang, Zhihui; Kubota, Mitsuhiro; He, Zhaohong; Kobayashi, Noriyuki

    2016-01-01

    LiOH·H2O nanoparticles supported on graphene oxide (GO) were facilely synthesized by a hydrothermal process. The mean diameter of nanoparticles on the integrated graphene sheet was about 5-10 nm showed by SEM and TEM results. XRD results suggested that the nanoparticles are in good agreement with the data of LiOH·H2O. The as-prepared sample showed a greatly enhanced thermal energy storage density and exhibit higher rate of heat release than pure lithium hydroxide, and thermal conductivity of composites increased due to the introduction of nano carbon. LiOH·H2O/GO nanocomposites are novel chemical heat storage materials for potential highly efficient energy system.

  17. Preparation and mechanism of calcium phosphate coatings on chemical modified carbon fibers by biomineralization

    Institute of Scientific and Technical Information of China (English)

    HUANG Su-ping; ZHOU Ke-chao; LI Zhi-you

    2008-01-01

    In order to prepare HA coatings on the carbon fibers, chemical modification and biomineralization processes were applied. The phase components, morphologies, and possible growth mechanism of calcium phosphate were studied by infrared spectroscopy(IR), X-ray diffractometry(XRD) and scanning electron microscopy(SEM). The results show that calcium phosphate coating on carbon fibers can be obtained by biomineralization. But the phase components and morphologies of calcium phosphate coatings are different due to different modification methods. Plate-like CaHPO4-2H2O (DCPD) crystals grow from one site of the active centre by HNO3 treatment. While on the para-aminobenzoic acid treated fibers, the coating is composed of nano-structural HA crystal homogeneously. This is because the -COOH functional groups of para-aminobenzoic acid graft on fibers, with negative charge and arranged structure, accelerating the HA crystal nucleation and crystallization on the carbon fibers.

  18. Piezoresistive Chemical Sensors Based on Functionalized Hydrogels

    Directory of Open Access Journals (Sweden)

    Margarita Guenther

    2014-06-01

    Full Text Available Thin films of analyte-specific hydrogels were combined with microfabricated piezoresistive pressure transducers to obtain chemomechanical sensors that can serve as selective biochemical sensors for a continuous monitoring of metabolites. The gel swelling pressure has been monitored in simulated physiological solutions by means of the output signal of piezoresistive sensors. The interference by fructose, human serum albumin, pH, and ionic concentration on glucose sensing was studied. With the help of a database containing the calibration curves of the hydrogel-based sensors at different values of pH and ionic strength, the corrected values of pH and glucose concentration were determined using a novel calibration algorithm.

  19. Carbon Nanotube-Based Chemical Sensors.

    Science.gov (United States)

    Meyyappan, M

    2016-04-27

    The need to sense gases and vapors arises in numerous scenarios in industrial, environmental, security and medical applications. Traditionally, this activity has utilized bulky instruments to obtain both qualitative and quantitative information on the constituents of the gas mixture. It is ideal to use sensors for this purpose since they are smaller in size and less expensive; however, their performance in the field must match that of established analytical instruments in order to gain acceptance. In this regard, nanomaterials as sensing media offer advantages in sensitivity, preparation of chip-based sensors and construction of electronic nose for selective detection of analytes of interest. This article provides a review of the use of carbon nanotubes in gas and vapor sensing. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. Chemical Sensors Based on Piezoresistive Cantilever Array

    Institute of Scientific and Technical Information of China (English)

    于晓梅; 张大成; 王丛舜; 杜先锋; 王小宝; 阮勇

    2003-01-01

    U-shaped and rectangle piezoresistive cantilever arrays have been designed with the analysing results of stress,noise and sensitivity of the cantilevers. Based on silicon micromachining technology, the piezoresistive cantilevers were fabricated by using polysilicon as the piezoresistive materials. With the measurement results of noise and sensitivity, the Hooge factor is calculated to be 3 × 10-3, the gauge factor is 27, and the minimum detectable deflection of piezoresistive cantilevers are calculated to be 1.0nm for rectangle cantilever and 0.5 nm for the Ushaped cantilever at a 6 V bias voltage and a 1000 Hz measurement bandwidth. Using polymer-coated cantilevers as individual sensors, their responses to water vapour and ammonia were tested by measuring their output voltage signals. The measured results show that the sensor sensitivity to ammonia can reach a few ppm and the sensor responses are quick.

  1. Chemical-Based Formulation Design: Virtual Experimentation

    DEFF Research Database (Denmark)

    Conte, Elisa; Gani, Rafiqul

    This paper presents a software, the virtual Product-Process Design laboratory (virtual PPD-lab) and the virtual experimental scenarios for design/verification of consumer oriented liquid formulated products where the software can be used. For example, the software can be employed for the design...... system engineering community, it is possible now to replace, at least, some of the experimental steps with efficient and validated model-based approaches. For example, the search space can be significantly reduced through computer-aided screenings of the active ingredient (AI), the solvent mixture......, the additives and/or their mixtures (formulations). Therefore, the experimental resources can focus on a few candidate product formulations to find the best product. The virtual PPD-lab allows various options for experimentations related to design and/or verification of the product. For example, the selection...

  2. Chemical, Physical, and Mechanical Characterization of Isocyanate Cross-linked Amine-Modified Silica Aerogels

    Science.gov (United States)

    Katti, Atul; Shimpi, Nilesh; Roy, Samit; Lu, Hongbing; Fabrizio, Eve F.; Dass, Amala; Capadona, Lynn A.; Leventis, Nicholas

    2006-01-01

    We describe a new mechanically strong lightweight porous composite material obtained by encapsulating the skeletal framework of amine-modified silica aerogels with polyurea. The conformal polymer coating preserves the mesoporous structure of the underlying silica framework and the thermal conductivity remains low at 0.041 plus or minus 0.001 W m(sup -1 K(sup -1). The potential of the new cross-linked silica aerogels for load-carrying applications was determined through characterization of their mechanical behavior under compression, three-point bending, and dynamic mechanical analysis (DMA). A primary glass transition temperature of 130 C was identified through DMA. At room temperature, results indicate a hyperfoam behavior where in compression cross-linked aerogels are linearly elastic under small strains (less than 4%) and then exhibit yield behavior (until 40% strain), followed by densification and inelastic hardening. At room temperature the compressive Young's modulus and the Poisson's ratio were determined to be 129 plus or minus 8 MPa and 0.18, respectively, while the strain at ultimate failure is 77% and the average specific compressive stress at ultimate failure is 3.89 x 10(exp 5) N m kg(sup -1). The specific flexural strength is 2.16 x 10(exp 4) N m kg(sup -1). Effects on the compressive behavior of strain rate and low temperature were also evaluated.

  3. An iterative modified kernel based on training data

    Institute of Scientific and Technical Information of China (English)

    Zhi-xiang ZHOU; Feng-qing HAN

    2009-01-01

    To improve performance of a support vector regression, a new method for a modified kernel function is proposed. In this method, information of all samples is included in the kernel function with conformal mapping. Thus the kernel function is data-dependent. With a random initial parameter, the kernel function is modified re-peatedly until a satisfactory result is achieved. Compared with the conventional model, the improved approach does not need to select parameters of the kernel function. Sim-ulation is carried out for the one-dimension continuous function and a case of strong earthquakes. The results show that the improved approach has better learning ability and forecasting precision than the traditional model. With the increase of the iteration number, the figure of merit decreases and converges. The speed of convergence depends on the parameters used in the algorithm.

  4. Discrimination of genetically modified sugar beets based on terahertz spectroscopy

    Science.gov (United States)

    Chen, Tao; Li, Zhi; Yin, Xianhua; Hu, Fangrong; Hu, Cong

    2016-01-01

    The objective of this paper was to apply terahertz (THz) spectroscopy combined with chemometrics techniques for discrimination of genetically modified (GM) and non-GM sugar beets. In this paper, the THz spectra of 84 sugar beet samples (36 GM sugar beets and 48 non-GM ones) were obtained by using terahertz time-domain spectroscopy (THz-TDS) system in the frequency range from 0.2 to 1.2 THz. Three chemometrics methods, principal component analysis (PCA), discriminant analysis (DA) and discriminant partial least squares (DPLS), were employed to classify sugar beet samples into two groups: genetically modified organisms (GMOs) and non-GMOs. The DPLS method yielded the best classification result, and the percentages of successful classification for GM and non-GM sugar beets were both 100%. Results of the present study demonstrate the usefulness of THz spectroscopy together with chemometrics methods as a powerful tool to distinguish GM and non-GM sugar beets.

  5. Chemical stability of prints made on hemp fibre based papers

    Directory of Open Access Journals (Sweden)

    Ivana Plazonić

    2016-11-01

    Full Text Available For paper industry and consequently graphic industry it is very important that fibres used in paper production provide high quality and printability of the paper. In pulp and paper industry fibres of cellulose pulp derived still predominantly from wood, but in the last few years the consumption of non-wood raw materials for that purpose has grown. This work presents research on the chemical stability of printed hemp fibre based papers to water, alcohol and alkali. Evaluation of chemical degradation on prints was determined through the spectrophotometric measurements. Deviations in colour of prints have shown that highest chemical stability provides prints made on industrially paper formed from mixture of hemp and post-consumer fibres with high share of inorganic components. Further, bleached hemp fibres in handmade 100 % hemp fibre based paper give prints with the lowest chemical stability.

  6. CANCER – THE ULTIMATUM FROM OUR CHEMICAL BASED CIVILIZATION

    Directory of Open Access Journals (Sweden)

    Shibabrata Pattanayak

    2014-06-01

    Full Text Available Cumulative effect of regular consumption of low amount of a large number of synthetic chemicals may create ultimately an environment inside our body leading to gereration of several types of diseases. Moreover, either DNA molecule of some tissue may get irreversible genetic damage or mutations or some tissue may start to grow abnormally due to the effect of those chemicals, both of which can lead to cancer, slowly but inevitably. To live with lesser number of hazardous diseases and for a healthy future generation, we must have to be conscious about these dangerous aspects of our chemical based civilization

  7. Efficient exploration of chemical space by fragment-based screening.

    Science.gov (United States)

    Hall, Richard J; Mortenson, Paul N; Murray, Christopher W

    2014-01-01

    Screening methods seek to sample a vast chemical space in order to identify starting points for further chemical optimisation. Fragment based drug discovery exploits the superior sampling of chemical space that can be achieved when the molecular weight is restricted. Here we show that commercially available fragment space is still relatively poorly sampled and argue for highly sensitive screening methods to allow the detection of smaller fragments. We analyse the properties of our fragment library versus the properties of X-ray hits derived from the library. We particularly consider properties related to the degree of planarity of the fragments.

  8. Modified versus classic alar base sutures after LeFort I osteotomy: a systematic review.

    Science.gov (United States)

    Liu, Xianwen; Zhu, Songsong; Hu, Jing

    2014-01-01

    The purpose of this systematic review is to evaluate the efficacy of a new modified alar base cinch suture by comparing it with the commonly used classic alar base suture after LeFort I osteotomy. A comprehensive search strategy was performed to include interventional studies involving the comparisons of alar base suturing methods after LeFort I osteotomy. Data analyses were conducted using the random-effects model. Three studies with 146 participants undergoing LeFort I maxillary osteotomy were included in this review. The results showed that, compared with the classic method, both modified transseptal alar base suture and modified reinsertion sutures significantly decreased postoperative alar and alar base widening. The modified alar base cinch suture was more effective than the classic alar base suture in maintaining preoperative alar and alar base width after LeFort I osteotomy. Copyright © 2014 Elsevier Inc. All rights reserved.

  9. Applicability of Vacuum Impregnation to Modify Physico-Chemical, Sensory and Nutritive Characteristics of Plant Origin Products—A Review

    Directory of Open Access Journals (Sweden)

    Elżbieta Radziejewska-Kubzdela

    2014-09-01

    Full Text Available Vacuum impregnation is a non-destructive method of introducing a solution with a specific composition to the porous matrices of fruit and vegetables. Mass transfer in this process is a result of mechanically induced differences in pressure. Vacuum impregnation makes it possible to fill large volumes of intercellular spaces in tissues of fruit and vegetables, thus modifying physico-chemical properties and sensory attributes of products. This method may be used, e.g., to reduce pH and water activity of the product, change its thermal properties, improve texture, color, taste and aroma. Additionally, bioactive compounds may be introduced together with impregnating solutions, thus improving health-promoting properties of the product or facilitating production of functional food.

  10. Chemically modified amino porphyrin/TiO2 for the degradation of Acid Black 1 under day light illumination.

    Science.gov (United States)

    Krishnakumar, Balu; Balakrishna, Avula; Arranja, Cláudia T; Dias, Carlos M F; Sobral, Abilio J F N

    2017-04-05

    In this paper, for the first time, chemically modified 5,10,15,20-meso-tetra-(para-amino)-phenyl-porphyrin/TiO2 (TPAPP/TiO2) was prepared and used for the degradation of an azo dye Acid Black 1 (AB 1) under direct sunlight. Initially, TiO2 was prepared by sol-gel method. Before making a TPAPP/TiO2 composite, the surface modification of TiO2 was carried out with glycidoxypropyltrimethoxy silane (GPTMS) which acts as a coupling agent. This is an epoxy terminated silane and could easily bond to the amino group of TPAPP through epoxy cleavage. The formation of TPAPP/TiO2 was confirmed by different characterization techniques such as FT-IR, XRD, SEM and DRS. The photocatalytic activity of TiO2 was highly influenced by TPAPP. A mechanism was proposed for AB 1 degradation by TPAPP/TiO2 under sun light.

  11. Chemically modified amino porphyrin/TiO2 for the degradation of Acid Black 1 under day light illumination

    Science.gov (United States)

    Krishnakumar, Balu; Balakrishna, Avula; Arranja, Cláudia T.; Dias, Carlos M. F.; Sobral, Abilio J. F. N.

    2017-04-01

    In this paper, for the first time, chemically modified 5,10,15,20-meso-tetra-(para-amino)-phenyl-porphyrin/TiO2 (TPAPP/TiO2) was prepared and used for the degradation of an azo dye Acid Black 1 (AB 1) under direct sunlight. Initially, TiO2 was prepared by sol-gel method. Before making a TPAPP/TiO2 composite, the surface modification of TiO2 was carried out with glycidoxypropyltrimethoxy silane (GPTMS) which acts as a coupling agent. This is an epoxy terminated silane and could easily bond to the amino group of TPAPP through epoxy cleavage. The formation of TPAPP/TiO2 was confirmed by different characterization techniques such as FT-IR, XRD, SEM and DRS. The photocatalytic activity of TiO2 was highly influenced by TPAPP. A mechanism was proposed for AB 1 degradation by TPAPP/TiO2 under sun light.

  12. Raman spectra investigation of the defects of chemical vapor deposited multilayer graphene and modified by oxygen plasma treatment

    Science.gov (United States)

    Li, Zongyao; Xu, Yu; Cao, Bing; Qi, Lin; He, Shunyu; Wang, Chinhua; Zhang, Jicai; Wang, Jianfeng; Xu, Ke

    2016-11-01

    Graphene, a two dimensional material, can be modified its properties by defects engineering. Here, we present Raman spectra studies of the multilayer graphene (MLG) fabricated by low-pressure chemical vapor deposition over copper foil, and report that the defects of MLG can be controlled by adjusting methane concentration. Moreover, MLG can be changed from metallic to semiconductoring properties by using oxygen plasma treatment, and we investigate the defects evolution of the graphene after exposing to oxygen plasma by Raman spectra. Our results indicate that the amount of defects in graphene can be changed by regulating the methane concentration and oxygen plasma exposure times, but the primary type of defect in MLG is still boundary-like defect. It is valuable for understanding the physics of defects evolution through artificially generated defects, and such defect engineering will greatly open up the future application of the novel material.

  13. Applicability of Vacuum Impregnation to Modify Physico-Chemical, Sensory and Nutritive Characteristics of Plant Origin Products—A Review

    Science.gov (United States)

    Radziejewska-Kubzdela, Elżbieta; Biegańska-Marecik, Róża; Kidoń, Marcin

    2014-01-01

    Vacuum impregnation is a non-destructive method of introducing a solution with a specific composition to the porous matrices of fruit and vegetables. Mass transfer in this process is a result of mechanically induced differences in pressure. Vacuum impregnation makes it possible to fill large volumes of intercellular spaces in tissues of fruit and vegetables, thus modifying physico-chemical properties and sensory attributes of products. This method may be used, e.g., to reduce pH and water activity of the product, change its thermal properties, improve texture, color, taste and aroma. Additionally, bioactive compounds may be introduced together with impregnating solutions, thus improving health-promoting properties of the product or facilitating production of functional food. PMID:25244012

  14. The application of solid sorbents for the purification of aluminum contaminated chemicals used as modifiers in electrothermal atomic absorption spectrometry.

    Science.gov (United States)

    Bulska, E; Pyrzyńska, K

    1996-06-01

    Various microcolumns with solid sorbents (ion exchange resins, functionalised cellulose sorbents, chelating resins) have been tested with respect to their ability for the purification of aluminum contaminated chemicals used as modifiers in electrothermal atomic absorption spectrometry. The purification of NaNO(3), Mg(NO(3))(2), K(2)SO(4) and (NH(4))(2)HPO(4) has been the most effective with an almost 100% efficiency, when Spheron-Oxine was used as chelating resin. The sorption of aluminum from KOH solution has been found to be very high (around 90%) for all investigated sorbents. However, the best results have been obtained with anion-exchange resins. It has been difficult to purify concentrated mineral acids (HCl, H(2)SO(4)). A retention of aluminum above 80% has been achieved only when Cellex P, Chelex 100 or Amberlite XAD-2 have been used.

  15. Interaction of plasma-generated water cluster ions with chemically-modified Si surfaces investigated by infrared absorption spectroscopy

    Directory of Open Access Journals (Sweden)

    Ayumi Hirano-Iwata

    2016-03-01

    Full Text Available We have investigated the interaction of water cluster ions generated by discharge plasma, with chemically modified Si surfaces using infrared absorption spectroscopy in the multiple internal reflection geometry. We observe that water cluster ions readily adsorb on SiO2-covered Si surfaces to form water droplets. We demonstrate that positively- and negatively-charged cluster ions adsorb on the SiO2-covered Si surface in different manners, indicating ionic interaction of the water droplets with the negatively-charged SiO2 surface. Water droplets formed on the protein-coated surface rupture the amide bond of the proteins, suggesting the function of protein decomposition of water cluster ions.

  16. Interaction of plasma-generated water cluster ions with chemically-modified Si surfaces investigated by infrared absorption spectroscopy

    Science.gov (United States)

    Hirano-Iwata, Ayumi; Matsumura, Ryosuke; Ma, Teng; Kimura, Yasuo; Niwano, Michio; Nishikawa, Kazuo

    2016-03-01

    We have investigated the interaction of water cluster ions generated by discharge plasma, with chemically modified Si surfaces using infrared absorption spectroscopy in the multiple internal reflection geometry. We observe that water cluster ions readily adsorb on SiO2-covered Si surfaces to form water droplets. We demonstrate that positively- and negatively-charged cluster ions adsorb on the SiO2-covered Si surface in different manners, indicating ionic interaction of the water droplets with the negatively-charged SiO2 surface. Water droplets formed on the protein-coated surface rupture the amide bond of the proteins, suggesting the function of protein decomposition of water cluster ions.

  17. Rehabilitation of irradiated patients with chemically modified and conventional SLA implants: five-year follow-up.

    Science.gov (United States)

    Nack, C; Raguse, J-D; Stricker, A; Nelson, K; Nahles, S

    2015-01-01

    The aim of this study is to evaluate the clinical and radiological parameters of standard SLA surface implants compared to chemically modified hydrophilic SLActive implants in irradiated patients after the initial 12-month loading period up to 5 years. Twenty patients with a mean age of 61·1 years were treated with dental implants after ablative surgery and radio-chemotherapy of oral cancer. All patients were non-smokers. The placement of 102 implants (50 SLA, 52 SLActive) was performed bilaterally according to a split-mouth design. Mean crestal bone changes were evaluated using standardised orthopantomographies and clinical parameters. Data were analysed using a Kaplan-Meier curve, Mann-Whitney U-test and two-factorial non-parametric analysis. The average observation period was 60 months. The amount of bone loss at the implant shoulder of SLA implants was mesial and distal 0·7 mm. The SLActive implants displayed a bone loss of mesial 0·6 mm as well as distal 0·7 mm after 5 years. Two SLA implants were lost before loading. One patient lost five implants due to recurrence of a tumour. The overall cumulative 12-month, 3-year and 5-year survival rate of SLA implants was 92%, 80% and 75·8% and of SLActive implants 94·2%, 78·8% and 74·4%, respectively. Eighteen implants were considered lost because the patients had died. Sandblasted acid-etched implants with or without a chemically modified surface can be used in irradiated patients with a high predictability of success. Lower implant survival rates in patients with irradiated oral cancer may be associated with systemic effects rather than peri-implantitis. © 2014 John Wiley & Sons Ltd.

  18. Evaluation of thorium based nuclear fuel. Chemical aspects

    Energy Technology Data Exchange (ETDEWEB)

    Konings, R.J.M.; Blankenvoorde, P.J.A.M.; Cordfunke, E.H.P.; Bakker, K.

    1995-07-01

    This report describes the chemical aspects of a thorium-based fuel cycle. It is part of a series devoted to the study of thorium-based fuel as a means to achieve a considerable reduction of the radiotoxicity of the waste from nuclear power production. Therefore special emphasis is placed on fuel (re-)fabrication and fuel reprocessing in the present work. (orig.).

  19. Efficient acetone-butanol-ethanol production (ABE) by Clostridium acetobutylicum XY16 immobilized on chemically modified sugarcane bagasse.

    Science.gov (United States)

    Kong, Xiangping; He, Aiyong; Zhao, Jie; Wu, Hao; Jiang, Min

    2015-07-01

    Sugarcane bagasse was chemically modified by polyethylenimine (PEI) and glutaraldehyde (GA) and then used as a support to immobilize Clostridium acetobutylicum XY16 in the process of butanol production. Compared with batch fermentation using unmodified sugarcane bagasse, 22.3 g/L total solvents were produced by cells immobilized on 4 g/L PEI treated sugarcane bagasse with high solvent productivity of 0.62 g/(L h) and glucose consumption rate of 1.67 g/(L h). Improvement of 14, 43, and 37 % in total solvent titer, solvent productivity and glucose consumption rate was observed, respectively. Enhanced solvent production of 25.14 g/L was obtained when using a high concentration of glucose of 80 g/L. Continuous fermentation was studied using PEI/GA modified sugarcane bagasse as immobilization support with a range of dilution which rates from 0.2 to 2.5 to find an optimal condition. The maximum solvent productivity of 11.32 g/(L h) was obtained at a high dilution rate of 2.0 h(-1).

  20. Factors affecting protein transfer into surfactant-isooctane solution: a case study of extraction behavior of chemically modified cytochrome c.

    Science.gov (United States)

    Ono, T; Goto, M

    1998-01-01

    The extraction mechanism of proteins by surfactant molecules in an organic solvent has been investigated using a chemically modified protein. We conducted guanidylation on lysine residues of cytochrome c by replacing their amino groups with homoarginine to enhance the protein-surfactant interaction. Results have shown that guanidylated cytochrome c readily forms a hydrophobic complex with dioleyl phosphoric acid (DOLPA) through hydrogen bonding between the phosphate moiety and the guanidinium groups. Although improved protein-surfactant interaction activated the formation of a hydrophobic complex at the interface, it could not improve the protein transfer in isooctane. It has been established that the protein extraction mechanism using surfactant molecules is mainly governed by two processes: formation of an interfacial complex at the oil-water interface and the subsequent solubilization of the complex into the organic phase. In addition, a kinetic study demonstrated that guanidylation of lysine accelerated the initial extraction rate of cytochrome c. This fact implies that the protein transferability from aqueous phase into organic phase depends on the protein-surfactant interaction which can be modified by protein surface engineering.

  1. Plasmonics Based Harsh Environment Compatible Chemical Sensors

    Energy Technology Data Exchange (ETDEWEB)

    Michael Carpenter

    2012-01-15

    Au-YSZ, Au-TiO{sub 2} and Au-CeO{sub 2} nanocomposite films have been investigated as a potential sensing element for high-temperature plasmonic sensing of H{sub 2}, CO, and NO{sub 2} in an oxygen containing environment. The Au-YSZ and Au-TiO{sub 2} films were deposited using PVD methods, while the CeO{sub 2} thin film was deposited by molecular beam epitaxy (MBE) and Au was implanted into the as-grown film at an elevated temperature followed by high temperature annealing to form well-defined Au nanoclusters. Each of the films were characterized by x-ray diffraction (XRD) and Rutherford backscattering spectrometry (RBS). For the gas sensing experiments, separate exposures to varying concentrations of H{sub 2}, CO, and NO{sub 2} were performed at a temperature of 500°C in oxygen backgrounds of 5.0, 10, and ~21% O{sub 2}. Changes in the localized surface plasmon resonance (LSPR) absorption peak were monitored during gas exposures and are believed to be the result of oxidation-reduction processes that fill or create oxygen vacancies in the respective metal oxides. This process affects the LSPR peak position either by charge exchange with the Au nanoparticles or by changes in the dielectric constant surrounding the particles. Hyperspectral multivariate analysis was used to gauge the inherent selectivity of the film between the separate analytes. From principal component analysis (PCA), unique and identifiable responses were seen for each of the analytes. Linear discriminant analysis (LDA) was also used on the Au-CeO{sub 2} results and showed separation between analytes as well as trends in gas concentration. Results indicate that each of the films are is selective towards O{sub 2}, H{sub 2}, CO, and NO{sub 2} in separate exposures. However, when the films were analyzed in a sensor array based experiment, ie simultaneous exposures to the target gases, PCA analysis of the combined response showed an even greater selective character towards the target gases. Combined

  2. Biocompatibility and surface structure of chemically modified immunoisolating alginate-PLL capsules.

    Science.gov (United States)

    Bünger, C M; Gerlach, C; Freier, T; Schmitz, K P; Pilz, M; Werner, C; Jonas, L; Schareck, W; Hopt, U T; de Vos, P

    2003-12-15

    Grafting of encapsulated living cells has the potential to cure a wide variety of diseases. Large-scale application of the technique, however, is hampered by insufficient biocompatibility of the capsules. A major factor in the biocompatibility of capsules is inadequate covering of the inflammatory poly-L-lysine (PLL) on the capsules' surface. In the present study, we investigate whether tissue responses against alginate-PLL capsules can be reduced by crosslinking the surface of the capsules with heparin or polyacrylic acid. Our transplant study in rats shows a tissue response composed of fibroblasts and macrophages on alginate-PLL-alginate and alginate-PLL-heparin capsules that was completely absent on alginate-PLL-polyacrylic acid capsules. Atomic force microscopy analyses of the capsules demonstrates that the improved biocompatibility of alginate-PLL-capsules by polyacrylic acid coating should not only be explained by a more adequate binding of PLL but also by the induction of a smoother surface. This study shows for the first time that biologic responses against capsules can be successfully deleted by chemically crosslinking biocompatible molecules on the surface of alginate-PLL capsules. Copyright 2003 Wiley Periodicals, Inc. J Biomed Mater Res 67A: 1219-1227, 2003

  3. MEDICAL IMAGE SEGMENTATION BASED ON A MODIFIED LEVEL SET ALGORITHM

    Institute of Scientific and Technical Information of China (English)

    Yang Yong; Lin Pan; Zheng Chongxun; Gu Jianwen

    2005-01-01

    Objective To present a novel modified level set algorithm for medical image segmentation. Methods The algorithm is developed by substituting the speed function of level set algorithm with the region and gradient information of the image instead of the conventional gradient information. This new algorithm has been tested by a series of different modality medical images. Results We present various examples and also evaluate and compare the performance of our method with the classical level set method on weak boundaries and noisy images. Conclusion Experimental results show the proposed algorithm is effective and robust.

  4. Multiple depositions of Ag nanoparticles on chemically modified agarose films for surface-enhanced Raman spectroscopy

    Science.gov (United States)

    Zhai, Wen-Lei; Li, Da-Wei; Qu, Lu-Lu; Fossey, John S.; Long, Yi-Tao

    2011-12-01

    A facile and cost-effective approach for the preparation of a surface-enhanced Raman spectroscopy (SERS) substrate through constructing silver nanoparticle/3-aminopropyltriethoxysilane/agarose films (Ag NPs/APTES/Agar film) on various solid supports is described. The SERS performance of the substrate was systematically investigated, revealing a maximum SERS intensity with four layers of the Ag NP deposition. The enhancement factor of the developed substrate was calculated as 1.5 × 107 using rhodamine 6G (R6G) as the probe molecule, and the reproducibility of the SERS signals was established. A high throughput screening platform was designed, manufactured and implemented which utilised the ability to cast agarose to assemble arrays. Quantitative analysis of 4-aminobenzoic acid (4-ABA) and 4-aminothiophenol (4-ATP) was achieved over a ~0.5 nM-0.1 μM range.A facile and cost-effective approach for the preparation of a surface-enhanced Raman spectroscopy (SERS) substrate through constructing silver nanoparticle/3-aminopropyltriethoxysilane/agarose films (Ag NPs/APTES/Agar film) on various solid supports is described. The SERS performance of the substrate was systematically investigated, revealing a maximum SERS intensity with four layers of the Ag NP deposition. The enhancement factor of the developed substrate was calculated as 1.5 × 107 using rhodamine 6G (R6G) as the probe molecule, and the reproducibility of the SERS signals was established. A high throughput screening platform was designed, manufactured and implemented which utilised the ability to cast agarose to assemble arrays. Quantitative analysis of 4-aminobenzoic acid (4-ABA) and 4-aminothiophenol (4-ATP) was achieved over a ~0.5 nM-0.1 μM range. Electronic supplementary information (ESI) available: the chemical structure of agarose, the SEM characterization of the synthesised Ag NPs, the calculation of the EF, the stability of the SERS substrate. See DOI: 10.1039/c1nr10956a

  5. The effect of chemically modified alginates on macrophage phenotype and biomolecule transport.

    Science.gov (United States)

    Bygd, Hannah C; Bratlie, Kaitlin M

    2016-07-01

    Macrophage (MΦ) reprogramming has received significant attention in applications such as cancer therapeutics and tissue engineering where the host immune response to biomaterials is crucial in determining the success or failure of an implanted device. Polymeric systems can potentially be used to redirect infiltrating M1 MΦs toward a proangiogenic phenotype. This work exploits the concept of MΦ reprogramming in the engineering of materials for improving the longevity of tissue engineering scaffolds. We have investigated the effect of 13 different chemical modifications of alginate on MΦ phenotype. Markers of the M1 response-tumor necrosis factor-α (TNF-α) and inducible nitric oxide synthase-and the M2 response-arginase-were measured and used to determine the ability of the materials to alter MΦ phenotype. It was found that some modifications were able to reduce the pro-inflammatory response of M1 MΦs, others appeared to amplify the M2 phenotype, and the results for two materials suggested they were able to reprogram a MΦ population from M1 to M2. These findings were supplemented by studies done to examine the permselectivity of the materials. Diffusion of TNF-α was completely prevented through some of these materials, while up to 84% was found to diffuse through others. The diffusion of insulin through the materials was statistically consistent. These results suggest that the modification of these materials might alter mass transport in beneficial ways. The ability to control polarization of MΦ phenotypes with immunoprotective materials has the potential to augment the success of tissue engineering scaffolds. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 104A: 1707-1719, 2016.

  6. A chemically modified [alpha]-amylase with a molten-globule state has entropically driven enhanced thermal stability

    Energy Technology Data Exchange (ETDEWEB)

    Siddiqui, Khawar Sohail; Poljak, Anne; De Francisci, Davide; Guerriero, Gea; Pilak, Oliver; Burg, Dominic; Raftery, Mark J.; Parkin, Don M.; Trewhella, Jill; Cavicchioli, Ricardo (Sydney); (New South)

    2010-11-15

    The thermostability properties of TAA were investigated by chemically modifying carboxyl groups on the surface of the enzyme with AMEs. The TAA{sub MOD} exhibited a 200% improvement in starch-hydrolyzing productivity at 60 C. By studying the kinetic, thermodynamic and biophysical properties, we found that TAA{sub MOD} had formed a thermostable, MG state, in which the unfolding of the tertiary structure preceded that of the secondary structure by at least 20 C. The X-ray crystal structure of TAA{sub MOD} revealed no new permanent interactions (electrostatic or other) resulting from the modification. By deriving thermodynamic activation parameters of TAA{sub MOD}, we rationalised that thermostabilisation have been caused by a decrease in the entropy of the transition state, rather than being enthalpically driven. Far-UV CD shows that the origin of decreased entropy may have arisen from a higher helical content of TAA{sub MOD}. This study provides new insight into the intriguing properties of an MG state resulting from the chemical modification of TAA.

  7. Phase Stability of Ce-Modified La2Zr2O7 Coatings and Chemical Compatibility with YSZ

    Science.gov (United States)

    Wu, Qiong; Ji, Xiaojuan; Peng, Haoran; Ren, Xianjing; Yu, Yueguang

    2016-04-01

    Ce-modified La2Zr2O7 powders, i.e., La2Zr2O7 (LZ), La2(Zr0.7Ce0.3)2O7 (LZ7C3), and La2(Zr0.3Ce0.7)2O7 (LZ3C7), were used to produce thermal barrier coatings by atmospheric plasma spray process. The chemical compatibility of the CeO2-doped La2Zr2O7 with the traditional YSZ was investigated in LZ-YSZ powder mixtures and LZ-YSZ bilayer coatings by x-ray diffraction and scanning electron microscope. The powder mixtures and coatings were aged at 1200 and 1300 °C for 100 h. The results showed that LZ and LZ7C3 presented single pyrochlore structure after the heat treatments at both 1200 and 1300 °C. For LZ3C7, however, fluorite structure was observed at 1300 °C, indicating a poor phase stability of LZ3C7 at the elevated temperature. The results further showed that La2(Zr0.3Ce0.7)2O7 reacted with YSZ in the bilayer ceramic coatings due to the diffusion of cerium, zirconium, and yttrium. While for La2Zr2O7(LZ) and La2(Zr0.7Ce0.3)2O7, a better chemical compatibility with YSZ was shown.

  8. Novel acrylic resin denture base with enhanced mechanical properties by the incorporation of PMMA-modified hydroxyapatite

    Institute of Scientific and Technical Information of China (English)

    Yingying Pan; Fengwei Liu; Dan Xu; Xiaoze Jiang; Hao Yu; Meifang Zhu

    2013-01-01

    A kind of novel acrylic resin denture base enhanced by PMMA-modified hydroxyapatite (M-HAP) was prepared and the modification effect of HAP on the mechanical properties of denture base material was investigated in the present study. HAP whiskers were prepared by hydrothermal homogeneous precipitation process and were silanized by the coupling agent, 3-methacryloxy propyl trimethoxyl silane (g-MPS), to induce the vinyl groups onto its surface. Methyl methacrylate (MMA) were then modified outside the vinyl functionalized HAP via polymerization to build a similar chemical structure with the acrylic matrix. A novel acrylic resin denture base was obtained through self-curing process with the incorporation of this PMMA-modified HAP, and the content of which ranged from 0 wt% to 0.8 wt%. Thermal gravimetric analysis (TGA), fourier transform infrared spectroscopy (FT-IR), scanning electron microscope (SEM), and universal testing apparatus were used to characterize M-HAP and corresponding denture base. The results showed that PMMA were successfully grafted onto the surface of HAP whiskers with up to 15 wt% and the modification turned out to be useful for the dispersion and compatibility of whiskers in the acrylic resin matrix. The mechanical properties of the prepared denture base samples were enhanced greatly after incorporating with M-HAP fillers. The optimal incorporated content of M-HAP was also investigated.

  9. Neutral anion receptors; synthesis and evaluation as sensing molecules in chemically modified field effect transistors (CHEMFETs)

    NARCIS (Netherlands)

    Antonisse, Martijn M.G.; Snellink-Ruel, Bianca H.M.; Yigit, Isteyfo; Engbersen, Johan F.J.; Reinhoudt, David N.

    1997-01-01

    new class of anion selective receptors is based on the neutral uranylsalophene building block as Lewis acidic binding site. Additional hydrogen bond accepting or donating moieties near the anion binding site offer the possibility of varying the binding selectivity. Field effect transistors chemicall

  10. Epoxy nanocomposites based on high temperature pyridinium-modified clays.

    Science.gov (United States)

    Zhang, Qingxin; Naito, Kimiyoshi; Qi, Ben; Kagawa, Yutaka

    2009-01-01

    Polymer/clay nanocomposites are generally fabricated by thermal curing or melt compounding at elevated temperatures, however the thermal stability of common alkyl ammonium treated clays is poor and decomposition occurs inevitably during high temperature processing. In this study, we modified clays with an aromatic pyridinium salt. Thermogravimetric analysis (TGA) showed that the onset degradation temperature (Td(onset)) and maximum decomposition temperature (Td(max)) of the pyridinium treatment clays was up to 310 and 457 degrees C respectively implying high thermal stability. The thermal decomposition behaviour of the pyridinium modified clays was discussed. A series of epoxy/clay nanocomposites were synthesized using a diglycidyl ether of bisphenol A (DGEBA) epoxy and diethyltoluene diamine (DETDA). The morphology of epoxy/clay nanocomposites was characterized with wide angle X-ray diffraction (WAXD) and transmission electron microscope (TEM), and intercalated structures were observed. The storage modulus of epoxy was increased but glass transition temperature was decreased with clay incorporation. The effects of clays on glass transition temperature (Tg) of epoxy were also discussed.

  11. Process Design and Evaluation for Chemicals Based on Renewable Resources

    DEFF Research Database (Denmark)

    Fu, Wenjing

    One of the key steps in process design is choosing between alternative technologies, especially for processes producing bulk and commodity chemicals. Recently, driven by the increasing oil prices and diminishing reserves, the production of bulk and commodity chemicals from renewable feedstocks has...... development of chemicals based on renewable feedstocks. As an example, this thesis especially focuses on applying the methodology in process design and evaluation of the synthesis of 5-hydroxymethylfurfural (HMF) from the renewable feedstock glucose/fructose. The selected example is part of the chemoenzymatic...... gained considerable interest. Renewable feedstocks usually cannot be converted into fuels and chemicals with existing process facilities due to the molecular functionality and variety of the most common renewable feedstock (biomass). Therefore new types of catalytic methods as well as new types...

  12. Enhanced compatibility of chemically modified titanium surface with periodontal ligament cells

    Energy Technology Data Exchange (ETDEWEB)

    Kado, T.; Hidaka, T. [Division of Periodontology and Endodontology, Department of Oral Rehabilitation, School of Dentistry, Health Sciences University of Hokkaido, 1757 Kanazawa, Ishikari-Tobetsu, Hokkaido 061-0293 (Japan); Aita, H. [Division of Occlusion and Removable Prosthodontics, Department of Oral Rehabilitation, School of Dentistry, Health Sciences University of Hokkaido, 1757 Kanazawa, Ishikari-Tobetsu, Hokkaido 061-0293 (Japan); Endo, K. [Division of Biomaterials and Bioengineering, Department of Oral Rehabilitation, School of Dentistry, Health Sciences University of Hokkaido, 1757 Kanazawa, Ishikari-Tobetsu, Hokkaido 061-0293 (Japan); Furuichi, Y., E-mail: furuichi@hoku-iryo-u.ac.jp [Division of Periodontology and Endodontology, Department of Oral Rehabilitation, School of Dentistry, Health Sciences University of Hokkaido, 1757 Kanazawa, Ishikari-Tobetsu, Hokkaido 061-0293 (Japan)

    2012-12-01

    Highlights: Black-Right-Pointing-Pointer Cell-adhesive molecules were covalently immobilized on a Ti surface. Black-Right-Pointing-Pointer Immobilized cell-adhesive molecules maintained native function on the Ti surface. Black-Right-Pointing-Pointer Immobilized collagen enhanced adhesion of periodontal ligament cells to the Ti. - Abstract: A simple chemical modification method was developed to immobilize cell-adhesive molecules on a titanium surface to improve its compatibility with human periodontal ligament cells (HPDLCs).The polished titanium disk was immersed in 1% (v/v) p-vinylbenzoic acid solution for 2 h to introduce carboxyl groups onto the surface. After rinsing with distilled deionized water, the titanium disk was dipped into 1.47% 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide solution containing 0.1 mg/ml Gly-Arg-Gly-Asp-Ser (GRGDS), human plasma fibronectin (pFN), or type I collagen from calf skin (Col) to covalently immobilize the cell-adhesive molecules on the titanium surface via formation of peptide bonds. X-ray photoelectron spectroscopy analyses revealed that cell-adhesive molecules were successfully immobilized on the titanium surfaces. The Col-immobilized titanium surface revealed higher values regarding nano rough characteristics than the as-polished titanium surface under scanning probe microscopy. The number of HPDLCs attached to both the pFN- and Col-immobilized titanium surfaces was twice that attached to the as-polished titanium surfaces. The cells were larger with the cellular processes that stretched to a greater extent on the pFN- and Col-immobilized titanium surfaces than on the as-polished titanium surface (p < 0.05). HPDLCs on the Col-immobilized titanium surfaces showed more extensive expression of vinculin at the tips of cell projections and more contiguously along the cell outline than on the as-polished, GRGDS-immobilized and pFN-immobilized titanium surfaces. It was concluded that cell-adhesive molecules successfully

  13. Structural and Chemical Diversity of Tl-Based Cuprate Superconductors

    Institute of Scientific and Technical Information of China (English)

    信赢

    2003-01-01

    The Tl-based cuprate superconductor family is the largest family in crystal structure and chemical composition among all high Tc cuprate superconductors. The Tl family can be divided into two sub-families, the Tl single layer family and the Tl double layer family, based on their crystal structural characteristics. The Tl single layer family is an ideal material for investigating the evolution of crystalline formation, charge carrier density, chemical composition, transport properties, superconductivity and their relationships. The Tl family contains almostall possible crystal structures discovered in high-Tc cuprate superconductors. Tl cuprate superconductors are of great importance not only in studying high-temperature superconductivity but also in commercial applications.

  14. Studies on filtered back-projection imaging reconstruction based on a modified wavelet threshold function

    Science.gov (United States)

    Wang, Zhengzi; Ren, Zhong; Liu, Guodong

    2016-10-01

    In this paper, the wavelet threshold denoising method was used into the filtered back-projection algorithm of imaging reconstruction. To overcome the drawbacks of the traditional soft- and hard-threshold functions, a modified wavelet threshold function was proposed. The modified wavelet threshold function has two threshold values and two variants. To verify the feasibility of the modified wavelet threshold function, the standard test experiments were performed by using the software platform of MATLAB. Experimental results show that the filtered back-projection reconstruction algorithm based on the modified wavelet threshold function has better reconstruction effect because of more flexible advantage.

  15. Modifiers in BASE and MICASE: A Matter of Academic Cultures or Lecturing Styles?

    Science.gov (United States)

    Lin, Chia-Yen

    2012-01-01

    Numerous studies have investigated the occurrence of modifiers in a variety of settings, especially academic research writing and casual spoken contexts. This study extends previous research in two ways: (1) it examines pragmatic force modifiers (PFMs) (and) in lectures in BASE and MICASE in order to reveal their functions specific to the…

  16. Simulating Chemical Kinetics Without Differential Equations: A Quantitative Theory Based on Chemical Pathways.

    Science.gov (United States)

    Bai, Shirong; Skodje, Rex T

    2017-08-17

    A new approach is presented for simulating the time-evolution of chemically reactive systems. This method provides an alternative to conventional modeling of mass-action kinetics that involves solving differential equations for the species concentrations. The method presented here avoids the need to solve the rate equations by switching to a representation based on chemical pathways. In the Sum Over Histories Representation (or SOHR) method, any time-dependent kinetic observable, such as concentration, is written as a linear combination of probabilities for chemical pathways leading to a desired outcome. In this work, an iterative method is introduced that allows the time-dependent pathway probabilities to be generated from a knowledge of the elementary rate coefficients, thus avoiding the pitfalls involved in solving the differential equations of kinetics. The method is successfully applied to the model Lotka-Volterra system and to a realistic H2 combustion model.

  17. Preparation and properties of environmental-friendly coatings based on carboxymethyl cellulose nitrate ester & modified alkyd.

    Science.gov (United States)

    Duan, Hongtao; Shao, Ziqiang; Zhao, Ming; Zhou, Zhenwen

    2016-02-10

    Amphipathic coating basic film-forming material carboxymethyl cellulose nitrate ester (CMCN) was synthesized and characterizations of CMCN with different ratio of functional groups were studied. Ratios of functional groups on each repeating units of CMCN have great importance in the decision of CMCN properties using as an amphipathic coating basic film-forming material and ratios of functional groups were the most concerned of the study. Ratios of functional groups on each repeating units of CMCN were measured by elemental analyzer and calculated. Series of experiments were conducted using different ratios of functional groups of CMCN. Thermal properties of CMCN were measured by FT-IR and TG. Densities of CMCN powders were measured. Aqueous coatings based on CMCN/alkyd (after chemical modified by coconut oil) were prepared and morphology & rheology of CMCN hydrophilic dispersions were measured using an Anton-Paar-Strasse 20A-8054 Graz analyzer. Contact angles between films based on CMCN and deionized water were recorded. Other properties of films were measured. CMCN with the etherification of carboxymethyl groups at 0.35-0.40, nitrate ester groups at 1.96-2.19 and hydroxyl groups at 0.46-0.64 per d-glucose was considered as the best film forming material.

  18. Electrochemical monitoring of biointeraction by graphene-based material modified pencil graphite electrode.

    Science.gov (United States)

    Eksin, Ece; Zor, Erhan; Erdem, Arzum; Bingol, Haluk

    2017-06-15

    Recently, the low-cost effective biosensing systems based on advanced nanomaterials have received a key attention for development of novel assays for rapid and sequence-specific nucleic acid detection. The electrochemical biosensor based on reduced graphene oxide (rGO) modified disposable pencil graphite electrodes (PGEs) were developed herein for electrochemical monitoring of DNA, and also for monitoring of biointeraction occurred between anticancer drug, Daunorubicin (DNR), and DNA. First, rGO was synthesized chemically and characterized by using UV-Vis, TGA, FT-IR, Raman Spectroscopy and SEM techniques. Then, the quantity of rGO assembling onto the surface of PGE by passive adsorption was optimized. The electrochemical behavior of rGO-PGEs was examined by cyclic voltammetry (CV). rGO-PGEs were then utilized for electrochemical monitoring of surface-confined interaction between DNR and DNA using differential pulse voltammetry (DPV) technique. Additionally, voltammetric results were complemented with electrochemical impedance spectroscopy (EIS) technique. Electrochemical monitoring of DNR and DNA was resulted with satisfying detection limits 0.55µM and 2.71µg/mL, respectively.

  19. Size-controlled nanoassemblies based on cyclodextrin-modified dextrans.

    Science.gov (United States)

    Wintgens, Véronique; Nielsen, Thorbjørn Terndrup; Larsen, Kim Lambertsen; Amiel, Catherine

    2011-09-09

    Nanoassemblies formed by host/guest interactions between two polymers in aqueous media are studied. Two types of polymers with the same dextran backbone are modified with adamantyl or βCD groups. The sizes of the spontaneously formed nanoassemblies depend on the βCD:Ada ratio and on the total concentration and composition of the mixtures. The results can be rationalized by assuming a core/shell structure of the nanoassemblies, the core resulting from associative phase separation of the two polymers and being stabilized by an external shell made of Ada-grafted dextran and containing ions adsorbed from the solution. Hydrophobic compounds such as benzophenone can be incorporated efficiently without inducing changes in properties of the nanoassemblies.

  20. Modified silica-based heterogeneous catalysts for etherification of glycerol

    Energy Technology Data Exchange (ETDEWEB)

    Gholami, Zahra, E-mail: zahra.gholami@petronas.com.my [Centralized Analytical Laboratory, Universiti Teknologi PETRONAS, Bandar Seri Iskandar, 31750 Tronoh, Perak (Malaysia); Abdullah, Ahmad Zuhairi, E-mail: chzuhairi@usm.my; Gholami, Fatemeh, E-mail: fgholami59@gmail.com [School of Chemical Engineering, Universiti Sains Malaysia, Engineering Campus,14300 Nibong Tebal, Penang (Malaysia); Vakili, Mohammadtaghi, E-mail: farshid3601@gmail.com [School of Industrial Technology, Universiti Sains Malaysia, 11800 Penang (Malaysia)

    2015-07-22

    The advent of mesoporous silicas such as MCM-41 has provided new opportunities for research into supported metal catalysis. The loading of metals into framework structures and particularly into the pores of porous molecular sieves, has long been of interest because of their potential catalytic activity. Stable heterogeneous mesoporous basic catalysts were synthesized by wet impregnation of MCM-41 with calcium nitrate and lanthanum nitrate. The surface and structural properties of the prepared catalysts were characterized using BET surface analysis, SEM and TEM. MCM-41 and modified MCM-41 were used in the solventless etherification of glycerol to produce diglycerol as the desired product. The reaction was performed at 250 °C for 8 h, and catalyst activity was evaluated. Catalytic etherification over the 20%Ca{sub 1.6}La{sub 0.6}/MCM-41 catalyst resulted in the highest glycerol conversion of 91% and diglycerol yield of 43%.

  1. SDRE Based Attitude Control Using Modified Rodriguez Parameters

    CERN Document Server

    Doruk, R Ozgur

    2011-01-01

    The purpose of this paper is to present an application of the State Dependent Riccati Equation (SDRE) method to satellite attitude control where the satellite kinematics is modeled by Modified Rodriguez Parameters (MRP). The SDRE methodology is applicable on special forms of nonlinear systems where satellite model is one of the candidates. It is not easy to find an analytical solution from the SDRE. Thus point wise solutions are interpolated with respect to the operating conditions. The point wise solutions are obtained from the MATLAB algorithms which are derived from the positive definite solutions of the SDRE. The global stability analysis is difficult due to the nature of the methodology. The resultant attitude controllers outside the breakpoints (the selected operating conditions for interpolation) are suboptimal. The performance of the designs is examined by simulations on MATLAB - Simulink environment. The simulation results show that, the designed attitude controllers are working satisfactorily even i...

  2. Incorporation of post-translational modified amino acids as an approach to increase both chemical and biological diversity of conotoxins and conopeptides.

    Science.gov (United States)

    Espiritu, Michael J; Cabalteja, Chino C; Sugai, Christopher K; Bingham, Jon-Paul

    2014-01-01

    Bioactive peptides from Conus venom contain a natural abundance of post-translational modifications that affect their chemical diversity, structural stability, and neuroactive properties. These modifications have continually presented hurdles in their identification and characterization. Early endeavors in their analysis relied on classical biochemical techniques that have led to the progressive development and use of novel proteomic-based approaches. The critical importance of these post-translationally modified amino acids and their specific assignment cannot be understated, having impact on their folding, pharmacological selectivity, and potency. Such modifications at an amino acid level may also provide additional insight into the advancement of conopeptide drugs in the quest for precise pharmacological targeting. To achieve this end, a concerted effort between the classical and novel approaches is needed to completely elucidate the role of post-translational modifications in conopeptide structure and dynamics. This paper provides a reflection in the advancements observed in dealing with numerous and multiple post-translationally modified amino acids within conotoxins and conopeptides and provides a summary of the current techniques used in their identification.

  3. A 3D Microfluidic Chip for Electrochemical Detection of Hydrolysed Nucleic Bases by a Modified Glassy Carbon Electrode

    Directory of Open Access Journals (Sweden)

    Jana Vlachova

    2015-01-01

    Full Text Available Modification of carbon materials, especially graphene-based materials, has wide applications in electrochemical detection such as electrochemical lab-on-chip devices. A glassy carbon electrode (GCE modified with chemically alternated graphene oxide was used as a working electrode (glassy carbon modified by graphene oxide with sulphur containing compounds and Nafion for detection of nucleobases in hydrolysed samples (HCl pH = 2.9, 100 °C, 1 h, neutralization by NaOH. It was found out that modification, especially with trithiocyanuric acid, increased the sensitivity of detection in comparison with pure GCE. All processes were finally implemented in a microfluidic chip formed with a 3D printer by fused deposition modelling technology. As a material for chip fabrication, acrylonitrile butadiene styrene was chosen because of its mechanical and chemical stability. The chip contained the one chamber for the hydrolysis of the nucleic acid and another for the electrochemical detection by the modified GCE. This chamber was fabricated to allow for replacement of the GCE.

  4. Durable chemical sensors based on field-effect transistors

    NARCIS (Netherlands)

    Reinhoudt, D.N.

    1995-01-01

    The design of durable chemical sensors based on field-effect transistors (FETs) is described. After modification of an ion-sensitive FET (ISFET) with a polysiloxane membrane matrix, it is possible to attach all electroactive components covalently. Preliminary results of measurements with a sodium-se

  5. Chemical Information in Scirus and BASE (Bielefeld Academic Search Engine)

    Science.gov (United States)

    Bendig, Regina B.

    2009-01-01

    The author sought to determine to what extent the two search engines, Scirus and BASE (Bielefeld Academic Search Engines), would be useful to first-year university students as the first point of searching for chemical information. Five topics were searched and the first ten records of each search result were evaluated with regard to the type of…

  6. Microstructure and property characterization of a modified zinc-base alloy and comparison with bearing alloys

    Science.gov (United States)

    Prasad, B. K.; Patwardhan, A. K.; Yegneswaran, A. H.

    1998-02-01

    The microstructure and physical, mechanical, and tribological properties of a modified zinc-base alloy have been characterized. In order to assess its utility as a bearing alloy, its properties have also been compared with those of a similarly processed conventional zinc-base alloy and a leaded-tin bronze (conforming to ZA27 and SAE 660 specifications, respectively) used for bearing applications. The modified zinc-base alloy shows promise in terms of better elevated-temperature strength and wear response at higher sliding speeds relative to the conventional zinc-base alloy. Interestingly, the wear behavior (especially the seizure pressure) of the modified alloy was also comparable to that of the bronze specimens at the maximum sliding speed, and was superior at the minimum sliding speed. The modified alloy also attained lower density and better hardness. Alloy behavior has been linked to the nature and type of the alloy microconstituents.

  7. Gravitational Cherenkov losses in theories based on modified Newtonian dynamics.

    Science.gov (United States)

    Milgrom, Mordehai

    2011-03-18

    Survival of high-energy cosmic rays (HECRs) against gravitational Cherenkov losses is shown not to cast strong constraints on modified Newtonian dynamics (MOND) theories that are compatible with general relativity (GR): theories that coincide with GR for accelerations ≫a(0) (a(0) is the MOND constant). The energy-loss rate, E, is many orders smaller than those derived in the literature for theories with no extra scale. Modification to GR, which underlies E, enters only beyond the MOND radius of the particle: r(M)=(Gp/ca(0))(1/2). The spectral cutoff, entering E quadratically, is thus r(M)(-1), not k(dB)=p/ℏ. Thus, E is smaller than published rates, which use k(dB), by a factor ∼(r(M)k(dB))(2)≈10(39)(cp/3×10(11)  Gev)(3). Losses are important only beyond D(loss)≈qℓ(M), where q is a dimensionless factor, and ℓ(M)=c(2)/a(0) is the MOND length, which is ≈2π times the Hubble distance.

  8. Using Physiologically-Based Pharmacokinetic Models to Incorporate Chemical and Non-Chemical Stressors into Cumulative Risk Assessment: A Case Study of Pesticide Exposures

    Directory of Open Access Journals (Sweden)

    Jonathan I. Levy

    2012-05-01

    Full Text Available Cumulative risk assessment has been proposed as an approach to evaluate the health risks associated with simultaneous exposure to multiple chemical and non-chemical stressors. Physiologically based pharmacokinetic/pharmacodynamic (PBPK/PD models can allow for the inclusion and evaluation of multiple stressors, including non-chemical stressors, but studies have not leveraged PBPK/PD models to jointly consider these disparate exposures in a cumulative risk context. In this study, we focused on exposures to organophosphate (OP pesticides for children in urban low-income environments, where these children would be simultaneously exposed to other pesticides (including pyrethroids and non-chemical stressors that may modify the effects of these exposures (including diet. We developed a methodological framework to evaluate chemical and non-chemical stressor impacts on OPs, utilizing an existing PBPK/PD model for chlorpyrifos. We evaluated population-specific stressors that would influence OP doses or acetylcholinesterase (AChE inhibition, the relevant PD outcome. We incorporated the impact of simultaneous exposure to pyrethroids and dietary factors on OP dose through the compartments of metabolism and PD outcome within the PBPK model, and simulated combinations of stressors across multiple exposure ranges and potential body weights. Our analyses demonstrated that both chemical and non-chemical stressors can influence the health implications of OP exposures, with up to 5-fold variability in AChE inhibition across combinations of stressor values for a given OP dose. We demonstrate an approach for modeling OP risks in the presence of other population-specific environmental stressors, providing insight about co-exposures and variability factors that most impact OP health risks and contribute to children’s cumulative health risk from pesticides. More generally, this framework can be used to inform cumulative risk assessment for any compound impacted by

  9. The optimal time-frequency atom search based on a modified ant colony algorithm

    Institute of Scientific and Technical Information of China (English)

    GUO Jun-feng; LI Yan-jun; YU Rui-xing; ZHANG Ke

    2008-01-01

    In this paper,a new optimal time-frequency atom search method based on a modified ant colony algorithm is proposed to improve the precision of the traditional methods.First,the discretization formula of finite length time-frequency atom is inferred at length.Second; a modified ant colony algorithm in continuous space is proposed.Finally,the optimal timefrequency atom search algorithm based on the modified ant colony algorithm is described in detail and the simulation experiment is carried on.The result indicates that the developed algorithm is valid and stable,and the precision of the method is higher than that of the traditional method.

  10. The effect of different annealing temperatures on tin and cadmium telluride phases obtained by a modified chemical route

    Energy Technology Data Exchange (ETDEWEB)

    Mesquita, Anderson Fuzer [Departamento de Química, CCE, Universidade Federal do Espírito Santo, Campus Goiabeiras, 29075-910 Vitória, Espírito Santo (Brazil); Porto, Arilza de Oliveira, E-mail: arilzaporto@yahoo.com.br [Departamento de Química, ICEx, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais (Brazil); Magela de Lima, Geraldo [Departamento de Química, ICEx, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais (Brazil); Paniago, Roberto [Departamento de Física, ICEx, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais (Brazil); Ardisson, José Domingos [Centro de Desenvolvimento da Tecnologia Nuclear, CDTN/CNEN, Belo Horizonte, Minas Gerais (Brazil)

    2012-11-15

    Graphical abstract: Display Omitted Highlights: ► Synthesis of cadmium and tin telluride. ► Chemical route to obtain pure crystalline cadmium and tin telluride. ► Effect of the annealing temperature on the crystalline phases. ► Removal of tin oxide as side product through thermal treatment. -- Abstract: In this work tin and cadmium telluride were prepared by a modification of a chemical route reported in the literature to obtain metallacycles formed by oxidative addition of tin-tellurium bonds to platinum (II). Through this procedure it was possible to obtain tin and cadmium telluride. X-ray diffraction and X-ray photoelectron spectroscopy were used to identify the crystalline phases obtained as well as the presence of side products. In the case of tin telluride it was identified potassium chloride, metallic tellurium and tin oxide as contaminants. The tin oxidation states were also monitored by {sup 119}Sn Mössbauer spectroscopy. The annealing in hydrogen atmosphere was chosen as a strategy to reduce the tin oxide and promote its reaction with the excess of tellurium present in the medium. The evolution of this tin oxide phase was studied through the annealing of the sample at different temperatures. Cadmium telluride was obtained with high degree of purity (98.5% relative weight fraction) according to the Rietveld refinement of X-ray diffraction data. The modified procedure showed to be very effective to obtain amorphous tin and cadmium telluride and the annealing at 450 °C has proven to be useful to reduce the amount of oxide produced as side product.

  11. Progress in chemical luminescence-based biosensors: A critical review.

    Science.gov (United States)

    Roda, Aldo; Mirasoli, Mara; Michelini, Elisa; Di Fusco, Massimo; Zangheri, Martina; Cevenini, Luca; Roda, Barbara; Simoni, Patrizia

    2016-02-15

    Biosensors are a very active research field. They have the potential to lead to low-cost, rapid, sensitive, reproducible, and miniaturized bioanalytical devices, which exploit the high binding avidity and selectivity of biospecific binding molecules together with highly sensitive detection principles. Of the optical biosensors, those based on chemical luminescence detection (including chemiluminescence, bioluminescence, electrogenerated chemiluminescence, and thermochemiluminescence) are particularly attractive, due to their high-to-signal ratio and the simplicity of the required measurement equipment. Several biosensors based on chemical luminescence have been described for quantitative, and in some cases multiplex, analysis of organic molecules (such as hormones, drugs, pollutants), proteins, and nucleic acids. These exploit a variety of miniaturized analytical formats, such as microfluidics, microarrays, paper-based analytical devices, and whole-cell biosensors. Nevertheless, despite the high analytical performances described in the literature, the field of chemical luminescence biosensors has yet to demonstrate commercial success. This review presents the main recent advances in the field and discusses the approaches, challenges, and open issues, with the aim of stimulating a broader interest in developing chemical luminescence biosensors and improving their commercial exploitation.

  12. Process Design and Evaluation for Chemicals Based on Renewable Resources

    DEFF Research Database (Denmark)

    Fu, Wenjing

    with recycle of the aqueous phase back to the enzymatic reaction. Costing analysis indicates the HMF production cost by the designed process is very sensitive to the dehydration reaction yield, the amount of solvent used in the whole process and the glucose price. In addition, increasing scale is also help......One of the key steps in process design is choosing between alternative technologies, especially for processes producing bulk and commodity chemicals. Recently, driven by the increasing oil prices and diminishing reserves, the production of bulk and commodity chemicals from renewable feedstocks has....... In addition, another characteristic of chemicals based on renewable feedstocks is that many alternative technologies and possible routes exist, resulting in many possible process flowsheets. The challenge for process engineers is then to choose between possible process routes and alternative technologies...

  13. A novel amperometric sensor for peracetic acid based on a polybenzimidazole-modified gold electrode

    Energy Technology Data Exchange (ETDEWEB)

    Hua, Mu-Yi, E-mail: huamy@mail.cgu.edu.t [Green Research Center, Department of Chemical and Materials Engineering, Chang Gung University, 259 Wen-Hwa 1st Rd., Kuei-Shan, Tao-Yuan 33302, Taiwan (China); Biosensor Group, Biomedical Engineering Research Center, Chang Gung University, 259 Wen-Hwa 1st Rd., Kuei-Shan, Tao-Yuan 33302, Taiwan (China); Chen, Hsiao-Chien [Green Research Center, Department of Chemical and Materials Engineering, Chang Gung University, 259 Wen-Hwa 1st Rd., Kuei-Shan, Tao-Yuan 33302, Taiwan (China); Biosensor Group, Biomedical Engineering Research Center, Chang Gung University, 259 Wen-Hwa 1st Rd., Kuei-Shan, Tao-Yuan 33302, Taiwan (China); Tsai, Rung-Ywan [Electronics and Optoelectronics Research Laboratories, Industrial Technology Research Institute, 195, Sec. 4, Chung Hsing Rd., Hsinchu 31040, Taiwan (China); Lin, Yu-Chen [Green Research Center, Department of Chemical and Materials Engineering, Chang Gung University, 259 Wen-Hwa 1st Rd., Kuei-Shan, Tao-Yuan 33302, Taiwan (China); Biosensor Group, Biomedical Engineering Research Center, Chang Gung University, 259 Wen-Hwa 1st Rd., Kuei-Shan, Tao-Yuan 33302, Taiwan (China)

    2011-04-30

    We have developed a peracetic acid (PAA) sensor based on a polybenzimidazole-modified gold (PBI/Au) electrode. Fourier transform infrared and X-ray photoelectron spectroscopy indicated that PAA oxidized 69.4% of the imine in PBI to form PBI N-oxide, increasing the electrochemical reduction current during cyclic voltammetry. The chemical oxidation of the PBI/Au electrode by PAA, followed by its electrochemical reduction, allowed PAA to be detected directly and consecutively by assessing its reduction current. The PAA sensor had a broad linear detection range (3.1 {mu}M-1.5 mM) and a rapid response time (3.9 s) at an applied potential of -0.3 V. Potentially interfering substances, such as hydrogen peroxide, acetic acid, and oxygen, had no effect on the ability of the probe to detect PAA, indicating high selectivity of the probe. Furthermore, the detection range, response time, and sensitivity of the sensor could all be improved by modification of the smooth planar electrode surface to a porous three-dimensional configuration. When compared to the analytical characteristics of other PAA sensors operating under optimal conditions, the three-dimensional PBI/Au electrode offers a rapid detection time, a usable linear range, and a relatively low detection limit.

  14. Electrical properties and thermal sensitivity of Ti/Y modified CuO-based ceramic thermistors

    Science.gov (United States)

    Yang, Bao; Zhang, Hong; Guo, Jia; Liu, Ya; Li, Zhicheng

    2016-09-01

    The Ti/Y modified CuO-based negative temperature coefficient (NTC) thermistors, Cu0.988-2y Y0.008Ti y O (TYCO; y = 0.01, 0.015, 0.03, 0.05 and 0.07), were synthesized through a wet-chemical method followed by a traditional ceramic sintering technology. The related phase component and electrical properties were investigated. XRD results show that the TYCO ceramics have a monoclinic structure as that of CuO crystal. The TYCO ceramics can be obtained at the sintering temperature 970°C-990°C, and display the typical NTC characteristic. The NTC thermal-sensitive constants of TYCO thermistors can be adjusted from 1112 to 3700 K by changing the amount of Ti in the TYCO ceramics. The analysis of complex impedance spectra revealed that both the bulk effect and grain boundary effect contribute to the electrical behavior and the NTC effect. Both the band conduction and electron-hopping models are proposed for the conduction mechanisms in the TYCO thermistors.

  15. Influence of soft bitumens on the chemical and rheological properties of reclaimed polymer-modified binders from the "old" surface-layer asphalt

    NARCIS (Netherlands)

    Liu, G.; Nielsen, E.; Komacka, J.; Leegwater, G.; Ven, M. van de

    2015-01-01

    Reclaimed asphalt (RA) that contains polymer-modified bitumen (PMB) offers a potential premium material contribution for recycling. This study investigated the influence of soft virgin bitumens on the chemical and rheological properties of three reclaimed PMBs from different "old" surface-layer

  16. Optical properties of carbon nanostructures produced by laser irradiation on chemically modified multi-walled carbon nanotubes

    Science.gov (United States)

    Santiago, Enrique Vigueras; López, Susana Hernández; Camacho López, Marco A.; Contreras, Delfino Reyes; Farías-Mancilla, Rurik; Flores-Gallardo, Sergio G.; Hernández-Escobar, Claudia A.; Zaragoza-Contreras, E. Armando

    2016-10-01

    This research focused on the nanosecond (Nd: YAG-1064 nm) laser pulse effect on the optical and morphological properties of chemically modified multi-walled carbon nanotubes (MWCNT). Two suspensions of MWCNT in tetrahydrofuran (THF) were prepared, one was submitted to laser pulses for 10 min while the other (blank) was only mechanically homogenized during the same time. Following the laser irradiation, the suspension acquired a yellow-amber color, in contrast to the black translucent appearance of the blank. UV-vis spectroscopy confirmed this observation, showing the blank a higher absorption. Additionally, photoluminescence measurements exhibited a broad blue-green emission band both in the blank and irradiated suspension when excited at 369 nm, showing the blank a lower intensity. However, a modification in the excitation wavelength produced a violet to green tuning in the irradiated suspension, which did not occur in the blank. Lastly, the electron microscopy analysis of the treated nanotubes showed the abundant formation of amorphous carbon, nanocages, and nanotube unzipping, exhibiting the intense surface modification produced by the laser pulse. Nanotube surface modification and the coexistence with the new carbon nanostructures were considered as the conductive conditions for optical properties modification.

  17. COL-3, a chemically modified tetracycline, inhibits lipopolysaccharide-induced microglia activation and cytokine expression in the brain.

    Directory of Open Access Journals (Sweden)

    Rawan Abdulhameed Edan

    Full Text Available Microglia activation results in release of proinflammatory molecules including cytokines, which contribute to neuronal damage in the central nervous system (CNS if not controlled. Tetracycline antibiotics such as minocycline inhibit microglial activation and cytokine expression during CNS inflammation. In the present study we found that administration of chemically modified tetracycline-3 (COL-3, inhibits lipopolysaccharide (LPS-induced microglial and p38 MAPK activation, as well as the increase in TNF-α, but not IL-1β expression, in the brains of BALB/c mice. COL-3 has been described to have no antibacterial activity. We observed that COL-3 had no activity against a Gram-negative bacteria, Escherichia coli; however surprisingly, COL-3 had antibacterial activity against a Gram-positive bacteria Staphylococcus aureus, with a minimum inhibitory concentration of 1 mg/ml. Our data show that COL-3 has some antibacterial activity against S. aureus, inhibits LPS-induced neuroinflammation, and displays potential as a therapeutic agent for treatment of conditions involving CNS inflammation.

  18. COL-3, a chemically modified tetracycline, inhibits lipopolysaccharide-induced microglia activation and cytokine expression in the brain.

    Science.gov (United States)

    Edan, Rawan Abdulhameed; Luqmani, Yunus A; Masocha, Willias

    2013-01-01

    Microglia activation results in release of proinflammatory molecules including cytokines, which contribute to neuronal damage in the central nervous system (CNS) if not controlled. Tetracycline antibiotics such as minocycline inhibit microglial activation and cytokine expression during CNS inflammation. In the present study we found that administration of chemically modified tetracycline-3 (COL-3), inhibits lipopolysaccharide (LPS)-induced microglial and p38 MAPK activation, as well as the increase in TNF-α, but not IL-1β expression, in the brains of BALB/c mice. COL-3 has been described to have no antibacterial activity. We observed that COL-3 had no activity against a Gram-negative bacteria, Escherichia coli; however surprisingly, COL-3 had antibacterial activity against a Gram-positive bacteria Staphylococcus aureus, with a minimum inhibitory concentration of 1 mg/ml. Our data show that COL-3 has some antibacterial activity against S. aureus, inhibits LPS-induced neuroinflammation, and displays potential as a therapeutic agent for treatment of conditions involving CNS inflammation.

  19. Tetracyclines and chemically modified tetracycline-3 (CMT-3) modulate cytokine secretion by lipopolysaccharide-stimulated whole blood.

    Science.gov (United States)

    Cazalis, Julia; Tanabe, Shin-ichi; Gagnon, Guy; Sorsa, Timo; Grenier, Daniel

    2009-04-01

    In addition to their bacteriostatic effect, tetracyclines, which are often used in the treatment of periodontitis, also present anti-inflammatory properties. In the present study, we investigated the effects of tetracycline (TC), doxycycline (doxy), and chemically modified tetracycline-3 (CMT-3) on the production of pro-inflammatory mediators and matrix metalloproteinases (MMPs) in an ex vivo human whole blood (WB) model stimulated with Porphyromonas gingivalis lipopolysaccharide (LPS). WB samples obtained from three periodontitis patients and six healthy subjects were stimulated with P. gingivalis LPS in the absence and presence of TC, doxy, or CMT-3. The secretion of interleukin-1beta (IL-1beta), interleukin-6 (IL-6), interleukin-8 (IL-8), MMP-8, and MMP-9 by the WB samples was determined using enzyme-linked immunosorbent assays. P. gingivalis LPS significantly increased the secretion of all cytokines and MMPs tested. While we observed inter-patient variations, TC, doxy, and CMT-3 caused reductions of LPS-induced cytokine secretion to various degrees. TC, doxy, and CMT-3 had no significant effect on MMP-8 and MMP-9 secretion by LPS-stimulated WB samples. In conclusion, we used a human WB model that takes into consideration relevant in vivo immune cell interactions in the presence of plasma proteins to show that TC, doxy, and CMT-3 can reduce the production of pro-inflammatory mediators. This property may contribute to the clinically proven benefits of these molecules in the treatment of periodontitis and other chronic inflammatory diseases.

  20. Compositionally and structurally modified SrTiO{sub 3} thin films prepared by chemical solution deposition

    Energy Technology Data Exchange (ETDEWEB)

    Spitzner, Dirk; Gutmann, Emanuel; Reibold, Marianne; Meyer, Dirk C. [Institut fuer Strukturphysik, Technische Universitaet Dresden (Germany); Mahltig, Boris [GMBU e.V., Arbeitsgruppe Funktionelle Schichten, Dresden (Germany)

    2009-07-01

    For electronic and architectural design of functional electroceramic devices, materials with a perovskite-type of structure play a major role. For high-k dielectric, sensing and thermal switching applications the introduction of Barium into SrTiO{sub 3}(STO) allows tuning the electrical properties by tuning the paraelectric-to-ferroelectric transition temperature. For thin film preparation a classic sol-gel route was modified by refluxing as well as solvothermal treatment of the as-synthesized sols. For treated sols the decomposition, phase evolution and transition behaviour differed and from X-ray diffraction (XRD) we observed a supression of foreign phases and a higher degree of compositional homogeneity. In this context also the homologous series of perovskite-related Ruddlesden-Popper (RP) phases promise an engineering of electrical properties by selecting a specific member. Exemplarily we realised the chemical solution deposition of epitaxial thin films of SrO(SrTiO{sub 3}){sub n} RP phases (n=1,2,3) on STO substrates. Structural characteristics of the films were analysed by means of XRD and HRTEM. An application as buffer layers exhibiting tuneable dielectric properties is conceivable.

  1. Glassy carbon electrode modified with a graphene oxide/poly(o-phenylenediamine) composite for the chemical detection of hydrogen peroxide

    Energy Technology Data Exchange (ETDEWEB)

    Nguyen, Van Hoa [School of Chemical Engineering, Yeungnam University, Gyeongsan, Gyeongbuk 712-749 (Korea, Republic of); Department of Chemistry, Nha Trang University, 2 Nguyen Dinh Chieu, Nha Trang (Viet Nam); Tran, Trung Hieu [School of Chemical Engineering, Yeungnam University, Gyeongsan, Gyeongbuk 712-749 (Korea, Republic of); Shim, Jae-Jin, E-mail: jjshim@yu.ac.kr [School of Chemical Engineering, Yeungnam University, Gyeongsan, Gyeongbuk 712-749 (Korea, Republic of)

    2014-11-01

    Conducting poly(o-phenylenediamine) (POPD)/graphene oxide (GO) composites were prepared using a facile and efficient method involving the in-situ polymerization of OPD in the presence of GO in an aqueous medium. Copper sulfate was used as an oxidative initiator for the polymerization of OPD. Scanning electron microscopy and transmission electron microscopy images showed that POPD microfibrils were formed and distributed relatively uniformly with GO sheets in the obtained composites. X-ray diffraction results revealed the highly crystal structure of POPD. This composite exhibited good catalytic activity and stability. These results highlight the potential applications of POPD/GO composites as excellent electrochemical sensors. The composites were used to modify glass carbon electrodes for the chemical detection of hydrogen peroxide in aqueous media. - Highlights: • Graphene oxide/poly(o-phenylenediamine) composites were prepared efficiently. • POPD microfibrils were distributed relatively uniformly with GO sheets. • The composite exhibited good catalytic activity and stability for H{sub 2}O{sub 2} sensing.

  2. Avaliação físico-química de bolo de chocolate com coberturas comestíveis à base de gelatina, ácido esteárico, amido modificado ou cera de carnaúba Physical and chemical evaluation of chocolate cake covered with gelatin, stearic acid, modified starch or "carnaúba" wax edible icing

    Directory of Open Access Journals (Sweden)

    Cibele Cristina Osawa

    2009-03-01

    Full Text Available Coberturas comestíveis biodegradáveis são uma alternativa às embalagens sintéticas, que causam preocupações ambientais. Este trabalho avaliou o efeito de diferentes tipos de coberturas sobre propriedades físico-químicas de bolo de chocolate durante a estocagem, em comparação com bolo sem cobertura (CO e bolo sem cobertura embalado em polipropileno (EMB. As seguintes coberturas foram aplicadas sobre os bolos: 10% gelatina (GE, 10% gelatina com 10% ácido esteárico (GE + AE, 18% cera de carnaúba (CE, 10% amido modificado (AM e fondant (FO. Os bolos foram avaliados durante 10 dias de estocagem. FO e EMB apresentaram menor perda de massa, enquanto todos os demais tratamentos apresentaram valores superiores a CO. GE, GE + AE e EMB apresentaram a menor redução da atividade de água, enquanto CE e CO apresentaram a maior redução. As superfícies dos bolos recobertos estavam mais duras que as de CO e EMB. Os maiores valores para dureza e mastigabilidade foram encontrados para CE e CO e os menores, para EMB, GE e GE + AE. Em relação à cor, GE + AE foi diferente dos demais tratamentos, devido à presença do ácido esteárico. Os resultados indicam que a perda de massa dos bolos pode ser atribuída também à perda de água das coberturas.Biodegradable edible icing or frosting is an alternative to synthetic packaging that causes environmental concerns. This work evaluated the effect of different types of frosting on the physical-chemical properties of chocolate cake during storage in comparison to cakes without icing or frosting (C and cakes without frosting packed in polypropylene (CP. The following frostings were applied to the cakes: 10% gelatin (GE, 10% gelatin with 10% stearic acid (GE+SA, 18% "carnaúba" wax (CW, 10% modified starch (MS, and fondant (FO. The cakes were analyzed during 10 days of storage. FO and CP presented the lowest mass loss while all other treatments presented higher values than C. GE, GE+SA, and CP presented

  3. Eletrodos quimicamente modificados aplicados à eletroanálise: uma breve abordagem Chemically modified electrodes applyes to electroanalysis: a brief presentation

    Directory of Open Access Journals (Sweden)

    Maria de Fátima Brito Souza

    1997-04-01

    Full Text Available Chemically modified electrodes (CMEs have been subject of considerable attention since its inception about 23 years ago. CMEs result of a deliberate immobilization of a modifier agent onto the electrode surface obtained through chemical reactions, chemisorption, composite formation or polymer coating. This immobilization seeks transfer the physicochemical properties of the modifier to the electrode surface and thus to dictate and control the behavior of the electrode/solution interface. In recent years the interest in CMEs has increased particularly to enhance the sensitivity and/or the selectivity of electroanalytical techniques. In general higher sensitivity and/or selectivity may be achieved by exploiting one or more of the following phenomena: electrocatalysis, preconcentration and interferents exclusion. This paper deals with the application of CMEs in electroanalysis, including a brief presentation of the more general procedures that have been employed for the modification of electrode surfaces.

  4. Interdependent chemical-electrochemical steps in retrometabolism-based drug and safer chemical design.

    Science.gov (United States)

    Tókés, B; Suciu, G; Nagy, G

    2002-02-01

    An extension of the retrometabolic based drug (chemical) design concept, specifically the soft drug approach, to the family of nitrone compounds is presented. Nitrones oppose oxidative challenges by virtue of their ability to very rapidly trap free radical species that are more stable and biochemically less harmful than the original molecular fragments. Moreover, the spin adducts may undergo further transformations including reaction with a second radical and decomposition (hydrolysis) to hydroxylamines and carbonyl compounds. Nitrones and their spin adducts may generate nitric oxide in vivo, which, like nitrones themselves, exerts a number of diverse activities in phylogenetically distant species as well as opposing effects in related biological systems. It was described as a major messenger in the cardiovascular, immune, and nervous systems, in which it plays regulatory, signaling, cytoprotective, and cytotoxic effects. Nitrones play an important role in the synthesis of drugs belonging to chemically and pharmacologically very different classes. A combined chemical-electrochemical synthesis of nitrones has been elaborated. These compounds may be obtained from aldehydes or ketones and N-substituted hydroxylamines. These reactions were performed directly, in situ in the electrochemical cell, where phenylhydroxylamine obtained by electroreduction of nitrobenzene derivatives reacts with the carbonyl compound introduced in the cell. The kinetic and thermodynamic parameters of the processes were determined by analyzing the adequate polarographic curves. Differences between purely chemical and mixed chemical-electrochemical methods are discussed. Analysis of the experimental data permits optimization of the investigated process from a preparative point of view. Effects of structural factors were systematically evaluated. The proposed method may be useful for combinatorial chemistry as well.

  5. Finding Important Nodes in Social Networks Based on Modified Pagerank

    Directory of Open Access Journals (Sweden)

    Li-qing Qiu

    2014-01-01

    Full Text Available Important nodes are individuals who have huge influence on social network. Finding important nodes in social networks is of great significance for research on the structure of the social networks. Based on the core idea of Pagerank, a new ranking method is proposed by considering the link similarity between the nodes. The key concept of the method is the use of the link vector which records the contact times between nodes. Then the link similarity is computed based on the vectors through the similarity function. The proposed method incorporates the link similarity into original Pagerank. The experiment results show that the proposed method can get better performance.

  6. Target searching based on modified implicit ROI encoding scheme

    Institute of Scientific and Technical Information of China (English)

    Bai Xu; Zhang Zhongzhao

    2008-01-01

    An EBCOT-based method is proposed to reduce the priority of background coefficients in the ROI code block without compromising algorithm complexity.The region of interest is encoded to a higher quality level than background,and the target searching time in video-guided penetrating missile can be shortened.Three kinds of coding schemes based on EBCOT are discussed.Experimental results demonstrate that the proposed method shows higher compression efficiency,lower complexity,and good reconstructed ROI image quality in the lower channel capacity.

  7. Relative embryotoxicity of two classes of chemicals in a modified zebrafish embryotoxicity test and comparison with their in vivo potencies.

    Science.gov (United States)

    Hermsen, Sanne A B; van den Brandhof, Evert-Jan; van der Ven, Leo T M; Piersma, Aldert H

    2011-04-01

    The zebrafish embryotoxicity test (ZET) is a fast and simple method to study chemical toxicity after exposure of the complete vertebrate embryo during embryogenesis in ovo. We developed a novel quantitative evaluation method to assess the development of the zebrafish embryo based on specific endpoints in time, the general morphology score (GMS) system. For teratogenic effects a separate scoring list was developed. The relative effects of eight glycol ethers and six 1,2,4-triazole anti-fungals were evaluated in this system and results were compared with in vivo developmental toxicity potencies. Methoxyacetic acid and ethoxyacetic acid appeared as the most potent glycol ether metabolites, inducing growth retardation and malformations. Other glycol ethers showed no developmental toxicity. Flusilazole appeared the most potent triazole, followed by hexaconazole, cyproconazole, triadimefon, myclobutanil and triticonazole, respectively. In general, the potency ranking of the compounds within their class in the ZET was comparable to their in vivo ranking. In conclusion, the ZET with the GMS system appears an efficient and useful test system for screening embryotoxic properties of chemicals within the classes of compounds tested. This alternative test method may also be useful for the detection of embryotoxic properties of other classes of chemicals.

  8. A modified soil water based Richards equation for layered soils

    Science.gov (United States)

    Kalinka, F.; Ahrens, B.

    2010-09-01

    Most Soil-Vegetation-Atmosphere-Transfer (SVAT) models like TERRA-ML (implemented e.g. in the CCLM model (www.clm-community.eu)) use the soil moisture based Richards equation to simulate vertical water fluxes in soils, assuming a homogeneous soil type. Recently, high-resolution soil type datasets (e.g. BüK 1000, only for Germany (Federal Institute for Geosciences and Natural Resources, BGR, www.bgr.bund.de) or Harmonized World Soil Database (HWSD, version 1.1, FAO/IIASA/ISRIC/ISSCAS/JRC, March 2009)) have been developed. Deficiencies in the numerical solution of the soil moisture based Richards equation may occur if inhomogeneous soil type data is implemented, because there are possibly discontinuities in soil moisture due to various soil type characteristics. One way to fix this problem is to use the potential based Richards equation, but this may lead to problems in conservation of mass. This presentation will suggest a possible numerical solution of the soil moisture based Richards equation for inhomogeneous soils. The basic idea is to subtract the equilibrium state of it from soil moisture fluxes. This should reduce discontinuities because each soil layer aspires the equilibrium state and therefore differences might be of the same order. First sensitivity studies have been done for the Main river basin, Germany.

  9. Problem-based learning biotechnology courses in chemical engineering.

    Science.gov (United States)

    Glatz, Charles E; Gonzalez, Ramon; Huba, Mary E; Mallapragada, Surya K; Narasimhan, Balaji; Reilly, Peter J; Saunders, Kevin P; Shanks, Jacqueline V

    2006-01-01

    We have developed a series of upper undergraduate/graduate lecture and laboratory courses on biotechnological topics to supplement existing biochemical engineering, bioseparations, and biomedical engineering lecture courses. The laboratory courses are based on problem-based learning techniques, featuring two- and three-person teams, journaling, and performance rubrics for guidance and assessment. Participants initially have found them to be difficult, since they had little experience with problem-based learning. To increase enrollment, we are combining the laboratory courses into 2-credit groupings and allowing students to substitute one of them for the second of our 2-credit chemical engineering unit operations laboratory courses.

  10. Exemplar-Based Image Inpainting Using a Modified Priority Definition.

    Directory of Open Access Journals (Sweden)

    Liang-Jian Deng

    Full Text Available Exemplar-based algorithms are a popular technique for image inpainting. They mainly have two important phases: deciding the filling-in order and selecting good exemplars. Traditional exemplar-based algorithms are to search suitable patches from source regions to fill in the missing parts, but they have to face a problem: improper selection of exemplars. To improve the problem, we introduce an independent strategy through investigating the process of patches propagation in this paper. We first define a new separated priority definition to propagate geometry and then synthesize image textures, aiming to well recover image geometry and textures. In addition, an automatic algorithm is designed to estimate steps for the new separated priority definition. Comparing with some competitive approaches, the new priority definition can recover image geometry and textures well.

  11. Exemplar-Based Image Inpainting Using a Modified Priority Definition.

    Science.gov (United States)

    Deng, Liang-Jian; Huang, Ting-Zhu; Zhao, Xi-Le

    2015-01-01

    Exemplar-based algorithms are a popular technique for image inpainting. They mainly have two important phases: deciding the filling-in order and selecting good exemplars. Traditional exemplar-based algorithms are to search suitable patches from source regions to fill in the missing parts, but they have to face a problem: improper selection of exemplars. To improve the problem, we introduce an independent strategy through investigating the process of patches propagation in this paper. We first define a new separated priority definition to propagate geometry and then synthesize image textures, aiming to well recover image geometry and textures. In addition, an automatic algorithm is designed to estimate steps for the new separated priority definition. Comparing with some competitive approaches, the new priority definition can recover image geometry and textures well.

  12. Solid Propellant Burn Rate Modifiers Based on Reactive Nanocomposite Materials

    Science.gov (United States)

    2010-10-26

    NaNO3 Al x x* x* x x x x** Mg x x x Al0.5Mg0.5 x MgH2 x x Si x x x Zr x x x x 2B·Ti*** x** Reactive Metal-Metalloid...composites B Reactive metals: Ti, Zr, Hf Nanostructured Al-based alloys Al Alloying components: W, Hf, Mg, MgH2 , Ti, Li, Zr, C * Metal-rich

  13. A modified Lee-Carter model for analysing short-base-period data.

    Science.gov (United States)

    Zhao, Bojuan Barbara

    2012-03-01

    This paper introduces a new modified Lee-Carter model for analysing short-base-period mortality data, for which the original Lee-Carter model produces severely fluctuating predicted age-specific mortality. Approximating the unknown parameters in the modified model by linearized cubic splines and other additive functions, the model can be simplified into a logistic regression when fitted to binomial data. The expected death rate estimated from the modified model is smooth, not only over ages but also over years. The analysis of mortality data in China (2000-08) demonstrates the advantages of the new model over existing models.

  14. Agent-Based Chemical Plume Tracing Using Fluid Dynamics

    Science.gov (United States)

    Zarzhitsky, Dimitri; Spears, Diana; Thayer, David; Spears, William

    2004-01-01

    This paper presents a rigorous evaluation of a novel, distributed chemical plume tracing algorithm. The algorithm is a combination of the best aspects of the two most popular predecessors for this task. Furthermore, it is based on solid, formal principles from the field of fluid mechanics. The algorithm is applied by a network of mobile sensing agents (e.g., robots or micro-air vehicles) that sense the ambient fluid velocity and chemical concentration, and calculate derivatives. The algorithm drives the robotic network to the source of the toxic plume, where measures can be taken to disable the source emitter. This work is part of a much larger effort in research and development of a physics-based approach to developing networks of mobile sensing agents for monitoring, tracking, reporting and responding to hazardous conditions.

  15. Spectroelectrochemical characterisation of copper salen-based polymer modified electrode

    OpenAIRE

    Martins, Madga; Vilas-Boas, Miguel; de Castro, B; Hillman, A.R.; Freire, C.

    2005-01-01

    Electrogenerated polymers based on copper salen-type complexes were characterised electrochemically and by in situ UV–vis and ex situ EPR spectroscopy. The films, poly[Cu(salen)] and poly[Cu(saltMe)], exhibit reversible oxidative electrochemical behaviour in a wide potential range (0.0–1.5 V). Different regimes for charge transport behaviour are accessed by manipulation of film thickness and experimental time scale: thin films (surface concentration, Γ < ca. 80 nmol cm−2) show thin-layer/surf...

  16. Molecularly Imprinted Polymer/Metal Organic Framework Based Chemical Sensors

    Directory of Open Access Journals (Sweden)

    Zhenzhong Guo

    2016-10-01

    Full Text Available The present review describes recent advances in the concept of molecular imprinting using metal organic frameworks (MOF for development of chemical sensors. Two main strategies regarding the fabrication, performance and applications of recent sensors based on molecularly imprinted polymers associated with MOF are presented: molecularly imprinted MOF films and molecularly imprinted core-shell nanoparticles using MOF as core. The associated transduction modes are also discussed. A brief conclusion and future expectations are described herein.

  17. Molecularly Imprinted Polymer/Metal Organic Framework Based Chemical Sensors

    OpenAIRE

    Zhenzhong Guo; Anca Florea; Mengjuan Jiang; Yong Mei; Weiying Zhang; Aidong Zhang; Robert Săndulescu; Nicole Jaffrezic-Renault

    2016-01-01

    The present review describes recent advances in the concept of molecular imprinting using metal organic frameworks (MOF) for development of chemical sensors. Two main strategies regarding the fabrication, performance and applications of recent sensors based on molecularly imprinted polymers associated with MOF are presented: molecularly imprinted MOF films and molecularly imprinted core-shell nanoparticles using MOF as core. The associated transduction modes are also discussed. A brief conclu...

  18. Chemically modified polymeric resins for solid-phase extraction and group separation prior to analysis by liquid or gas chromatography

    Energy Technology Data Exchange (ETDEWEB)

    Schmidt, L.W.

    1993-07-01

    Polystyrene divinylbenzene was modified by acetyl, sulfonic acid, and quaternary ammonium groups. A resin functionalized with an acetyl group was impregnated in a PTFE membrane and used to extract and concentrate phenolic compounds from aqueous samples. The acetyl group created a surface easily wetted, making it an efficient adsorbent for polar compounds in water. The membrane stabilized the resin bed. Partially sulfonated high surface area resins are used to extract and group separate an aqueous mixture of neutral and basic organics; the bases are adsorbed electrostatically to the sulfonic acid groups, while the neutraons are adsorbed hydrophobically. A two-step elution is then used to separate the two fractions. A partially functionalized anion exchange resin is used to separate organic acids and phenols from neutrals in a similar way. Carboxylic acids are analyzed by HPLC and phenols by GC.

  19. Acellular dermal matrix based nipple reconstruction: A modified technique

    Directory of Open Access Journals (Sweden)

    Raghavan Vidya

    2017-09-01

    Full Text Available Nipple areolar reconstruction (NAR has evolved with the advancement in breast reconstruction and can improve self-esteem and, consequently, patient satisfaction. Although a variety of reconstruction techniques have been described in the literature varying from nipple sharing, local flaps to alloplastic and allograft augmentation, over time, loss of nipple projection remains a major problem. Acellular dermal matrices (ADM have revolutionised breast reconstruction more recently. We discuss the use of ADM to act as a base plate and strut to give support to the base and offer nipple bulk and projection in a primary procedure of NAR with a local clover shaped dermal flap in 5 breasts (4 patients. We used 5-point Likert scales (1 = highly unsatisfied, 5 = highly satisfied to assess patient satisfaction. Median age was 46 years (range: 38–55 years. Nipple projection of 8 mm, 7 mm, and 7 mms were achieved in the unilateral cases and 6 mm in the bilateral case over a median 18 month period. All patients reported at least a 4 on the Likert scale. We had no post-operative complications. It seems that nipple areolar reconstruction [NAR] using ADM can achieve nipple projection which is considered aesthetically pleasing for patients.

  20. Integration Processes of Delay Differential Equation Based on Modified Laguerre Functions

    Directory of Open Access Journals (Sweden)

    Yeguo Sun

    2012-01-01

    Full Text Available We propose long-time convergent numerical integration processes for delay differential equations. We first construct an integration process based on modified Laguerre functions. Then we establish its global convergence in certain weighted Sobolev space. The proposed numerical integration processes can also be used for systems of delay differential equations. We also developed a technique for refinement of modified Laguerre-Radau interpolations. Lastly, numerical results demonstrate the spectral accuracy of the proposed method and coincide well with analysis.

  1. Heterogeneous Web Data Extraction Algorithm Based On Modified Hidden Conditional Random Fields

    OpenAIRE

    Cui Cheng

    2014-01-01

    As it is of great importance to extract useful information from heterogeneous Web data, in this paper, we propose a novel heterogeneous Web data extraction algorithm using a modified hidden conditional random fields model. Considering the traditional linear chain based conditional random fields can not effectively solve the problem of complex and heterogeneous Web data extraction, we modify the standard hidden conditional random fields in three aspects, which are 1) Using the hidden Markov mo...

  2. INVESTIGATING EFFECTS OF AMINE BASED MODIFIER ON RECYCLED ASPHALT SHINGLES BLENDING

    OpenAIRE

    2014-01-01

    A laboratory study was conducted to investigate the effects of Amine based modifier on rheological characteristics of particle filled viscous medium such as asphalt binder in presence of Recycled Asphalt Shingles (RAS). In this study, virgin asphalt binder (PG 64-22), three different percentages (20, 30 and 40%) of tear-off shingles and modifiers; Rediset, Evotherm and Bio-binder were used. The tear-off shingles acquired from local reroofing company in Greensboro, North Carolina; were finely ...

  3. Wearable Ring-Based Sensing Platform for Detecting Chemical Threats.

    Science.gov (United States)

    Sempionatto, Juliane R; Mishra, Rupesh K; Martín, Aida; Tang, Guangda; Nakagawa, Tatsuo; Lu, Xiaolong; Campbell, Alan S; Lyu, Kay Mengjia; Wang, Joseph

    2017-10-11

    This work describes a wireless wearable ring-based multiplexed chemical sensor platform for rapid electrochemical monitoring of explosive and nerve-agent threats in vapor and liquid phases. The ring-based sensor system consists of two parts: a set of printed electrochemical sensors and a miniaturized electronic interface, based on a battery-powered stamp-size potentiostat, for signal processing and wireless transmission of data. A wide range of electrochemical capabilities have thus been fully integrated into a 3D printed compact ring structure, toward performing fast square-wave voltammetry and chronoamperometric analyses, along with interchangeable screen-printed sensing electrodes for the rapid detection of different chemical threats. High analytical performance is demonstrated despite the remarkable miniaturization and integration of the ring system. The attractive capabilities of the wearable sensor ring system have been demonstrated for sensitive and rapid voltammetric and amperometric monitoring of nitroaromatic and peroxide explosives, respectively, along with amperometric biosensing of organophosphate (OP) nerve agents. Such ability of the miniaturized wearable sensor ring platform to simultaneously detect multiple chemical threats in both liquid and vapor phases and alert the wearer of such hazards offers considerable promise for meeting the demands of diverse defense and security scenarios.

  4. Thermal Conductivity Based on Modified Laser Flash Measurement

    Science.gov (United States)

    Lin, Bochuan; Ban, Heng; Li, Chao; Scripa, Rosalia N.; Su, Ching-Hua; Lehoczky, Sandor L.

    2005-01-01

    The laser flash method is a standard method for thermal diffusivity measurement. It employs single-pulse heating of one side of a thin specimen and measures the temperature response of the other side. The thermal diffusivity of the specimen can be obtained based on a one-dimensional transient heat transfer analysis. This paper reports the development of a theory that includes a transparent reference layer with known thermal property attached to the back of sample. With the inclusion of heat conduction from the sample to the reference layer in the theoretical analysis, the thermal conductivity and thermal diffusivity of sample can be extracted from the temperature response data. Furthermore, a procedure is established to select two points from the data to calculate these properties. The uncertainty analysis indicates that this method can be used with acceptable levels of uncertainty.

  5. Xanthine Biosensor Based on Didodecyldimethylammonium Bromide Modified Pyrolytic Graphite Electrode

    Institute of Scientific and Technical Information of China (English)

    TANG,Ji-Lin(唐纪琳); HAN,Xiao-Jun(韩晓军); HUANG,Wei-Min(黄卫民); WANG,Er-Kang(汪尔康)

    2002-01-01

    The vesicle of didodecyldimethylammonium bromide (DDAB)which contained tetrathiafulvalene (TTF) was mixed with xanthine oxidase, and the mixture was cast on the pyrolytic graphite electrode. The lipid films were used to supply a biological environment resembling biomembrane on the surface of the electrode. TTF was used as a mediator because of its high electron-transfer efficiency. A novel xanthine biosensor based on cast DDAB film was developed. The effects of pH and operating potential were explored for optimum analytical performance by using the amperometric method. The response time of the biosensor was less than 10 s. The detection limit of the biosensor was 3.2 × 10-7 mol/L and the liner range was from 4 × 10-7 mol/L to 2.4 × 10-6 mol/L.

  6. Rule-Based Classification of Chemical Structures by Scaffold.

    Science.gov (United States)

    Schuffenhauer, Ansgar; Varin, Thibault

    2011-08-01

    Databases for small organic chemical molecules usually contain millions of structures. The screening decks of pharmaceutical companies contain more than a million of structures. Nevertheless chemical substructure searching in these databases can be performed interactively in seconds. Because of this nobody has really missed structural classification of these databases for the purpose of finding data for individual chemical substructures. However, a full deck high-throughput screen produces also activity data for more than a million of substances. How can this amount of data be analyzed? Which are the active scaffolds identified by an assays? To answer such questions systematic classifications of molecules by scaffolds are needed. In this review it is described how molecules can be hierarchically classified by their scaffolds. It is explained how such classifications can be used to identify active scaffolds in an HTS data set. Once active classes are identified, they need to be visualized in the context of related scaffolds in order to understand SAR. Consequently such visualizations are another topic of this review. In addition scaffold based diversity measures are discussed and an outlook is given about the potential impact of structural classifications on a chemically aware semantic web.

  7. A Standardized Chemically Modified Curcuma longa Extract Modulates IRAK-MAPK Signaling in Inflammation and Potentiates Cytotoxicity

    Directory of Open Access Journals (Sweden)

    Minakshi Rana

    2016-07-01

    Full Text Available The TLR/IL-1R pathway is a critical signaling module that is misregulated in pathologies like inflammation and cancer. Extracts from turmeric (Curcuma longa L. enriched in curcumin and carbonyls like turmerones have been shown to exert potent anti-inflammatory effects. The present study evaluated the anti-inflammatory activity, cytotoxic effect and the underlying mechanism of a novel chemically modified, non-carbonyl compound enriched Curcuma longa L. (C. longa extract (CMCE. CMCE (1 or 10 µg/mL; 14 h significantly decreased LPS (50-100 ng/mL induced TNF-α and IL-1β production in THP-1 cells, human, and mouse whole blood as measured by ELISA. LPS-induced IRAK1, MAPK activation, TLR4 expression, TLR4-MyD88 interaction and IκBα degradation were significantly reduced in CMCE pre-treated THP-1 cells as assessed by Western blotting. CMCE (30, 100 and 300 mg/kg; 10 days p.o. pre-treated and LPS (10 mg/kg challenged Swiss mice exhibited attenuated plasma TNF-α, IL-1β, nitrite, aortic iNOS expression and vascular dysfunction. In a PI permeability assay, cell lines derived from acute myeloid leukemia were most sensitive to the cytotoxic effects of CMCE. Analysis of Sub-G1 phase, Annexin V-PI positivity, loss of mitochondrial membrane potential, increased caspase-3 and PARP-1 activation confirmed CMCE induced apoptosis in HL-60 cells. IRAK inhibition also sensitized HL-60 cells to CMCE induced cytotoxicity. The present study defines the mechanism underlying the action of CMCE and suggests a therapeutic potential for its use in sepsis and leukemia.

  8. A Standardized Chemically Modified Curcuma longa Extract Modulates IRAK-MAPK Signaling in Inflammation and Potentiates Cytotoxicity.

    Science.gov (United States)

    Rana, Minakshi; Maurya, Preeti; Reddy, Sukka S; Singh, Vishal; Ahmad, Hafsa; Dwivedi, Anil K; Dikshit, Madhu; Barthwal, Manoj K

    2016-01-01

    The TLR/IL-1R pathway is a critical signaling module that is misregulated in pathologies like inflammation and cancer. Extracts from turmeric (Curcuma longa L.) enriched in curcumin and carbonyls like turmerones have been shown to exert potent anti-inflammatory effects. The present study evaluated the anti-inflammatory activity, cytotoxic effect and the underlying mechanism of a novel chemically modified, non-carbonyl compound enriched Curcuma longa L. (C. longa) extract (CMCE). CMCE (1 or 10 μg/mL; 14 h) significantly decreased LPS (50-100 ng/mL) induced TNF-α and IL-1β production in THP-1 cells, human, and mouse whole blood as measured by ELISA. LPS-induced IRAK1, MAPK activation, TLR4 expression, TLR4-MyD88 interaction, and IκBα degradation were significantly reduced in CMCE pre-treated THP-1 cells as assessed by Western blotting. CMCE (30, 100, and 300 mg/kg; 10 days p.o.) pre-treated and LPS (10 mg/kg) challenged Swiss mice exhibited attenuated plasma TNF-α, IL-1β, nitrite, aortic iNOS expression, and vascular dysfunction. In a PI permeability assay, cell lines derived from acute myeloid leukemia were most sensitive to the cytotoxic effects of CMCE. Analysis of Sub-G1 phase, Annexin V-PI positivity, loss of mitochondrial membrane potential, increased caspase-3, and PARP-1 activation confirmed CMCE induced apoptosis in HL-60 cells. IRAK inhibition also sensitized HL-60 cells to CMCE induced cytotoxicity. The present study defines the mechanism underlying the action of CMCE and suggests a therapeutic potential for its use in sepsis and leukemia.

  9. Investigation of chemical modifiers for sulfur determination in diesel fuel samples by high-resolution continuum source graphite furnace molecular absorption spectrometry using direct analysis

    Energy Technology Data Exchange (ETDEWEB)

    Huber, Charles S. [Instituto Federal Sul-rio-grandense, Câmpus Pelotas, Pelotas, RS (Brazil); Universidade Federal do Rio Grande do Sul, Instituto de Química, Porto Alegre, RS (Brazil); Vale, Maria Goreti R. [Universidade Federal do Rio Grande do Sul, Instituto de Química, Porto Alegre, RS (Brazil); Instituto Nacional de Ciência e Tecnologia do CNPq, INCT de Energia e Ambiente, Universidade Federal da Bahia, Salvador, BA (Brazil); Welz, Bernhard [Instituto Nacional de Ciência e Tecnologia do CNPq, INCT de Energia e Ambiente, Universidade Federal da Bahia, Salvador, BA (Brazil); Universidade Federal de Santa Catarina, Departamento de Química, Florianópolis, SC (Brazil); Andrade, Jailson B. [Instituto Nacional de Ciência e Tecnologia do CNPq, INCT de Energia e Ambiente, Universidade Federal da Bahia, Salvador, BA (Brazil); Dessuy, Morgana B., E-mail: mbdessuy@ufrgs.br [Universidade Federal do Rio Grande do Sul, Instituto de Química, Porto Alegre, RS (Brazil); Instituto Nacional de Ciência e Tecnologia do CNPq, INCT de Energia e Ambiente, Universidade Federal da Bahia, Salvador, BA (Brazil)

    2015-06-01

    High-resolution continuum source graphite furnace molecular absorption spectrometry has been applied for sulfur determination in diesel fuel. The sharp rotational lines of the carbon monosulfide molecule (formed during the vaporization step) were used to measure the absorbance. The analytical line at 258.056 nm was monitored using the sum of three pixels. Different chemical modifiers were investigated and the mixture of palladium and magnesium was used as chemical modifier in combination with iridium as permanent modifier. L-Cysteine was chosen as sulfur standard and the calibration was done against aqueous standard solutions. The proposed method was applied for the analyses of four diesel samples: two S10 samples and two S500 samples. The trueness of the method was checked with a certified reference material (CRM) of sulfur in diesel fuel (NIST 2724b). Accurate results, for samples and CRM, were achieved after a dilution with propan-1-ol. The following figures of merit were obtained: characteristic mass of 17 ± 3 ng, limit of detection and limit of quantification of 1.4 mg kg{sup −1} and 4.7 mg kg{sup −1}, respectively. - Highlights: • Ir, Ru and Zr were investigated as permanent modifiers. • Ca, Mg, Pd and Pd/Mg were investigated as modifiers in solution. • Indirect determination of sulfur monitoring the molecular absorbance of the CS • Direct analysis of diesel samples using a dilution in propan-1-ol.

  10. Case modifying of high-speed cutting database based on CSP and similarity theory

    Institute of Scientific and Technical Information of China (English)

    Kejun XIANG; Zhanqiang LIU; Xing AI

    2009-01-01

    By analyzing the reasoning of a high-speed cutting database system, a case modifying method is put forward. According to the variables' difference of the solution part in a case, a constraint satisfaction problem (CSP) and similarity calculation are used to modify a case. The constraint relationship of discrete variables is described by establishing a rule knowledge base. The algorithm of CSP is used to solve the discrete variable constraint problem. On the basis of the high-speed cutting theory, a similarity calculation formula is deduced to calculate the consecutive variables. The CSP and similarity calculation are applied to case modifying, which is possible to automatically modify cases in the high-speed cutting database system.

  11. Synthesis of methylprednisolone loaded ibuprofen modified inulin based nanoparticles and their application for drug delivery.

    Science.gov (United States)

    Zhang, Luzhong; Li, Yue; Wang, Caiping; Li, Guicai; Zhao, Yahong; Yang, Yumin

    2014-09-01

    Ibuprofen modified inulin was synthesized through a direct esterification linkage in which the in situ activation of the carboxylic acid with N,N'-carbonyldiimidazole was carried out. The critical aggregation concentration of the ibuprofen modified inulin was determined by using pyrene as the fluorescence probe. Methylprednisolone loaded nanoparticles were prepared by the self-assembly of the ibuprofen modified inulin copolymer and methylprednisolone. In vitro release of the methylprednisolone and the cytotoxicity of the methylprednisolone loaded nanoparticles against RSC-96 cells were evaluated. Since the ibuprofen and methylprednisolone could stimulate a significant neurite growth and diminish the human neurological deficits after the spinal cord injury, the methylprednisolone loaded nanoparticles based on the ibuprofen modified inulin copolymer may have a great potential in the synergetic effect treatment for spinal cord injury.

  12. Activation of the ERK1/2 Signaling Pathway during the Osteogenic Differentiation of Mesenchymal Stem Cells Cultured on Substrates Modified with Various Chemical Groups

    Directory of Open Access Journals (Sweden)

    Bing Bai

    2013-01-01

    Full Text Available The current study examined the influence of culture substrates modified with the functional groups –OH, –COOH, –NH2, and –CH3 using SAMs technology, in conjunction with TAAB control, on the osteogenic differentiation of rabbit BMSCs. The CCK-8 assay revealed that BMSCs exhibited substrate-dependent cell viability. The cells plated on –NH2- and –OH-modified substrates were well spread and homogeneous, but those on the –COOH- and –CH3-modified substrates showed more rounded phenotype. The mRNA expression of BMSCs revealed that –NH2-modified substrate promoted the mRNA expression and osteogenic differentiation of the BMSCs. The contribution of ERK1/2 signaling pathway to the osteogenic differentiation of BMSCs cultured on the –NH2-modified substrate was investigated in vitro. The –NH2-modified substrate promoted the expression of integrins; the activation of FAK and ERK1/2. Inhibition of ERK1/2 activation by PD98059, a specific inhibitor of the ERK signaling pathway, blocked ERK1/2 activation in a dose-dependent manner, as revealed for expression of Cbfα-1 and ALP. Blockade of ERK1/2 phosphorylation in BMSCs by PD98059 suppressed osteogenic differentiation on chemical surfaces. These findings indicate a potential role for ERK in the osteogenic differentiation of BMSCs on surfaces modified by specific chemical functional groups, indicating that the microenvironment affects the differentiation of BMSCs. This observation has important implications for bone tissue engineering.

  13. Bismuth Modified Carbon-Based Electrodes for the Determination of Selected Neonicotinoid Insecticides

    Directory of Open Access Journals (Sweden)

    Marko Rodić

    2011-05-01

    Full Text Available Two types of bismuth modified electrodes, a bismuth-film modified glassy carbon (BiF-GCE and a bismuth bulk modified carbon paste, were applied for the determination of selected nitroguanidine neonicotinoid insecticides. The method based on an ex situ prepared BiF-GCE operated in the differential pulse voltammetric (DPV mode was applied to determine clothianidin in the concentration range from 2.5 to 23 μg cm−3 with a relative standard deviation (RSD not exceeding 1.5%. The tricresyl phosphate-based carbon paste electrodes (TCP-CPEs, bulk modified with 5 and 20 w/w% of bismuth, showed a different analytical performance in the determination of imidacloprid, regarding the peak shape, potential window, and noise level. The TCP-CPE with 5% Bi was advantageous, and the developed DPV method based on it allowed the determination in the concentration range from 1.7 to 60 μg cm−3 with an RSD of 2.4%. To get a deeper insight into the morphology of the bismuth-based sensor surfaces, scanning electron microscopic measurements were performed of both the surface film and the bulk modified electrodes.

  14. Thermal Stability and Ablation Behavior of Modified Polydimethylsiloxane-Based Polyurethane Composites Reinforced with Polyhedral Oligomeric Silsesquioxane.

    Science.gov (United States)

    Han, Zhongyou; Xi, Yukun; Kwon, Younghwan

    2016-02-01

    Series of polydimethylsiloxane (PDMS)-based polyurethane (PU)/polyhedral oligomeric silsesquioxane (POSS) composites are prepared using ether or polyether modified diol/polyol PDMS prepolymers, isophorone diisocyanate (IPDI) and either non-reactive or reactive POSS. The effect of POSS incorporated chemically or physically, number of ethylene oxide units and crosslinking on PDMS based PU is investigated in terms of thermal stability and ablation properties. The ablation property is measured using an oxyacetylene torch test, and the ablation rate is evaluated. The results show that POSS molecules make a considerable influence on the ablative resistance, because they act as protective silica forming precursors under oxyacetylene condition. POSS molecules, especially methyl POSS, in PU matrix leads to the formation of densely accumulated spherical silica layers on the top of the ablated surface, resulting in improved ablation resistance.

  15. Application of Nation/Cobalt Hexacyanoferrate Chemically Modified Electrodes for the Determination of Electroinactive Cations by Ion Chromatography

    Institute of Scientific and Technical Information of China (English)

    XU,Ji-Ming(徐继明); XIAN,Yue-Zhong(鲜跃仲); SHI,Guo-Yue(施国跃); LI,Jin-Hua(李金花); JIN Li-Tong(金利通)

    2002-01-01

    An amperometric detector based on the chemical modification of Nafion and cobalt(H) hexacyanoferrate(Ⅱ, Ⅲ) thin film (Nafion/Co-CN-Fe) onto a glassy carbon (GC) electrode was firslly developed for the determination of electroinactive cations (Li+, Na+, K+, Rb+, Cs+ and NH4+) in single column ion chromatography. A set of well-defined peaks of electroinactive cation was obtained. The relative standard deviations (RSDs)of - peak height (nA) for these cations were all below 3.8%. The cations were detected conveniently in the linear concentration range of 6.0× 10-6-5.0 × 10-3 mol/L and their correlation coefficients were all above 0.99. Tne detection limiits of the cations were 9.2 × 10- 6 mol/L for Li + , 3.4 ×10-6 mol/L for Na+ , 6.3 × 10-7 mol/L for K+ , 7.8 × 10-7 mol/L for Rb+ , 6.2 × 10-7 mol/L for Cs+ and 6.2 × 10-6 mol/L for NH4+ , at a signal-noise ratio of 3. The method was quick, sensitive, simple and was successfully applied to the analysis of rainwater samples. The electrode was stable for a 2 week period of operation with no evidence of chemical or mechanical deterioration.

  16. Spectrofluorimetric determination of stoichiometry and association constants of the complexes of harmane and harmine with beta-cyclodextrin and chemically modified beta-cyclodextrins.

    Science.gov (United States)

    Martín, L; León, A; Olives, A I; Del Castillo, B; Martín, M A

    2003-06-13

    The association characteristics of the inclusion complexes of the beta-carboline alkaloids harmane and harmine with beta-cyclodextrin (beta-CD) and chemically modified beta-cyclodextrins such as hydroxypropyl-beta-cyclodextrin (HPbeta-CD), 2,3-di-O-methyl-beta-cyclodextrin (DMbeta-CD) and 2,3,6-tri-O-methyl-beta-cyclodextrin (TMbeta-CD) are described. The association constants vary from 112 for harmine/DMbeta-CD to 418 for harmane/HPbeta-CD. The magnitude of the interactions between the host and the guest molecules depends on the chemical and geometrical characteristics of the guest molecules and therefore the association constants vary for the different cyclodextrin complexes. The steric hindrance is higher in the case of harmine due to the presence of methoxy group on the beta-carboline ring. The association obtained for the harmane complexes is stronger than the one observed for harmine complexes except in the case of harmine/TMbeta-CD. Important differences in the association constants were observed depending on the experimental variable used in the calculations (absolute value of fluorescence intensity or the ratio between the fluorescence intensities corresponding to the neutral and cationic forms). When fluorescence intensity values were considered, the association constants were higher than when the ratio of the emission intensity for the cationic and neutral species was used. These differences are a consequence of the co-existence of acid-base equilibria in the ground and in excited states together with the complexation equilibria. The existence of a proton transfer reaction in the excited states of harmane or harmine implies the need for the experimental dialysis procedure for separation of the complexes from free harmane or harmine. Such methodology allows quantitative results for stoichiometry determinations to be obtained, which show the existence of both 1:1 and 1:2 beta-carboline alkaloid:CD complexes with different solubility properties.

  17. Chemically modified carbon paste and membrane sensors for the determination of benzethonium chloride and some anionic surfactants (SLES, SDS, and LABSA): Characterization using SEM and AFM.

    Science.gov (United States)

    Issa, Yousry M; Mohamed, Sabrein H; Baset, Mohamed Abd-El

    2016-08-01

    Chemically modified carbon-paste (CMCP) and membrane- sensors based on incorporating benzothonium-tetraphenylborate (BT-TPB) were constructed for the analysis of benzethonium chloride, and some other surfactants such as sodium lauryl ether sulphate (SLES), sodium dodecyl sulphate (SDS), and linear alkylbenzene sulphonic acid (LABSA). All sensors showed good sensitivity and reverse wide linearity over a concentration range of 5.97×10(-7) to 1.00×10(-3) and 5.96×10(-7) to 3.03×10(-3)molL(-1) with limit of detection of 3.92×10(-7)and 3.40×10(-7)molL(-1) for membrane and chemically modified carbon paste sensors, respectively, with respect to benzethonium chloride (BT.Cl). They could be used over a wide pH range of 2.0-10.0. The thermal coefficients of membrane and CMCP sensors are 5.40×10(-4), 1.17×10(-4)V/°C, respectively. The sensors indicated a wide selectivity over different inorganic cations. The effect of soaking on the surface morphology of the membrane sensor was studied using EDX-SEM and AFM techniques. The response time was <10s The freshly prepared, exhausted membrane, and CMCP sensors were successfully applied for the potentiometric determination of the pure BT.Cl solution. They were also used for the determination of its pharmaceutical formulation Dermoplast(®) antibacterial spray (20% benzocaine+0.2% benzethonium chloride) with recovery values ranging from 97.54±1.70 to 101.25±1.12 and from 96.32±2.49 to 101.23±2.15%. The second goal of these sensors is the potentiometric determination of different surfactants such as SLES, SDS, and LABSA with good recovery values using BT.Cl as a titrant in their pure forms, and in samples containing one of them (shampoo, Touri(®) dishwashing liquid, and waste water). The statistical analysis of the obtained data was studied.

  18. Aging of a New Niobium-Modified MAR-M247 Nickel-Based Superalloy

    Science.gov (United States)

    Baldan, Renato; Azevedo e Silva, Paulo Ricardo Soares; Nunes, Carlos Angelo; Coelho, Gilberto Carvalho

    2013-08-01

    MAR-M247 is a nickel-based superalloy that contains 3 wt.% Ta (weight percent of tantalum). Considering the chemical similarity between tantalum and niobium (Nb) and the lower cost of Nb, a modified MAR-M247 superalloy was produced with total replacement of Ta by Nb in this work. The samples were previously solutioned at 1260°C for 8 h and then aged at different times (between 5 and 80 h) and temperatures (between 780 and 980°C). The microstructures of the aged samples were characterized with a scanning electron microscope (SEM and FEG-SEM, both with EDS). Simulations of the MC carbide and γ' fraction and the Ta and Nb content in both MC carbide and γ' phase were performed with Thermo-Calc software (TT_Ni8 database) and simulations of the γ' growth rate and γ' mean diameter were performed with JMatPro software. MC carbide with high Hf content was observed in all the aged samples, in agreement with thermodynamic simulation results. The equilibrium γ' fraction decreases from 67 mol.% at 780°C to 52 mol.% at 980°C. Good agreement between the calculated and experimentally determined γ' particle size was also found. The growth rate of γ' at 980°C is about 8 times higher than that at 780°C and 3 times higher than that at 880°C. The hardness values do not change considerably after aging at 780 and 880°C. However, these values decrease significantly after aging at 980°C.

  19. Graphene-based room-temperature implementation of a modified Deutsch-Jozsa quantum algorithm.

    Science.gov (United States)

    Dragoman, Daniela; Dragoman, Mircea

    2015-12-04

    We present an implementation of a one-qubit and two-qubit modified Deutsch-Jozsa quantum algorithm based on graphene ballistic devices working at room temperature. The modified Deutsch-Jozsa algorithm decides whether a function, equivalent to the effect of an energy potential distribution on the wave function of ballistic charge carriers, is constant or not, without measuring the output wave function. The function need not be Boolean. Simulations confirm that the algorithm works properly, opening the way toward quantum computing at room temperature based on the same clean-room technologies as those used for fabrication of very-large-scale integrated circuits.

  20. Optimisation of Direct Copper Determination in Human Breast Milk Without Digestion by Zeeman Graphite Furnace Atomic Absorption Spectrophotometry with Two Chemical Modifiers.

    Science.gov (United States)

    Pineau, Alain; Fauconneau, Bernard; Marrauld, Annie; Lebeau, Alexandra; Hankard, Regis; Guillard, Olivier

    2015-08-01

    Milk is an important food in the human diet, and copper (Cu) in human milk is indispensable to children's normal growth and development. It is consequently important that Cu deficiency, occurring in malnourished women or in malabsorption following bariatric surgery, be prevented. The objective of this work is to provide hospital-based paediatricians with a tool enabling rapid measurement of Cu in human breast milk through a technique that biology laboratories can easily apply. Using electrothermal atomic absorption spectrophotometry with Zeeman correction, we have optimized this method with two chemical modifiers and without digestion for analytical procedure. Detection limits and quantification limits for Cu in human milk were found to be 0.077 and 0.26 μmol/L, respectively. Within-run (n = 30) and between-run (n = 15) variations in a pool of human milk samples were 1.50 and 3.62%, respectively. Average recoveries ranged from 98.67 to 100.61%. The reliability of this method was also confirmed by analysing certified reference material (10%). In breast milk samples collected from 100 lactating mothers, Cu mean (±1 SD) was 7.09 ± 1.60 μmol/L. In conclusion, with minimal preparation and quick determination, the method proposed is suitable for measurement of Cu in human breast milk.

  1. Assessment of a modified and optimised method for determining chemical oxygen demand of solid substrates and solutions with high suspended solid content.

    Science.gov (United States)

    Raposo, F; de la Rubia, M A; Borja, R; Alaiz, M

    2008-07-15

    A modified approach to determine the chemical oxygen demand (COD) of solid substrates based on the DIN 38414-S9 standard method is proposed. The adapted procedure is assessed and compared with standard methods widely used for water and wastewater such as the American Public Health Association-American Water Works Association-Water Pollution Control Federation (APHA-AWWA-WPCF) standard methods 5220 B-open reflux (SM-OR) and 5220 D-closed reflux colorimetric (SM-CR). Solutions with high suspended concentration of solids, as well as digestates from an anaerobic reactor, were used during the comparative test. For solid substrates, the COD recovery was about 100% when the proposed method was used. For solutions with solid content higher than 20 g TS L(-1), the recovery was only completed when the proposed method was used, showing that the methods traditionally employed are not very appropriate for samples with the described characteristics. For instance, percentages of COD recovery in the ranges of 77.3-87.1% and 89.4-94.1% were achieved when the SM-OR and SM-CR methods were used, respectively.

  2. [Rationality of commercial specification of rhubarb based on chemical analysis].

    Science.gov (United States)

    Wang, Jiabo; Zhang, Xueru; Xiao, Xiaohe; Chu, Xiaohui; Zhou, Canping; Jin, Cheng; Yan, Dan

    2010-02-01

    The differences of 34 rhubarb samples collected on the market and at producing area were investigated by chemical analysis on the contents of anthraquinones and chromatographic fingerprints, in order to assess the rationality of the commercial specification of rhubarb. The results indicated that the commercial specification of rhubarb was not correlated to the contents of anthraquinones as well as the price. The chromatographic fingerprints of rhubarb samples from different producing area were dissimilar, while the commercial specifications were difficult to be separated. Generally, the rhubarb samples produced in famous-region contained more anthraquinones. This demonstrated rationality on the traditional records of the famous-region of rhubarb from a chemical view. In this study, it was firstly reported that rhubarb could be categorized into two types, chrysophanol-type and rhein-type, based on the proportion of the two constituents in the total anthraquinones after acid hydrohysis. It was found that the rhubarb samples of rhein-type were mostly produced in famous-regions, such as Qinghai, Xizang, West Sichuan and Gansu. The literatures reported that rhein was superior to chrysophanol at many pharmacological effects and pharmacokinetic properties. Hence, we primarily considered that rhein-type rhubarb might be high-quality. These results were helpful to improve the commercial specification of rhubarb from a view of chemical information.

  3. Exploration of chemical space based on 4-anilinoquinazoline.

    Science.gov (United States)

    Li, D-D; Hou, Y-P; Wang, W; Zhu, H-L

    2012-01-01

    Chemical space is defined as all possible small organic molecules, including those present in biological systems, which is so vast that so far only a tiny fraction of it has been explored. Indeed, a thorough examination of all "chemical space" is practically impossible. The success of three EGFR inhibitors (Gefitnib, Erlotinib, Lapatinib) suggests that 4-anilinoquinazoline scaffold is still worth developing in the future. To date hundreds of this sort of derivatives have been synthesized and show potent anticancer activities. Most of the compounds have been proved to be EGFR/HER2 kinase inhibitors, binding at the hinge region of the ATP site and some lead compounds have been optimized against a number of different kinases, including VEGFR-2, Src, Aurora A/B, Tpl, Clk and PDE10A. Now there is now a rich pipeline of novel anticancer agents based on 4-anilinoquinazoline in early phase clinical trials. This review will highlight the exploration of chemical space of 4-anilinoquinazoline in the past ten years and we hope that increasing knowledge of the SAR and cellular processes underlying the antitumor-activity of anilinoquinazoline derivatives will be beneficial to the rational design of new generation of small molecule anticancer drugs.

  4. 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.

  5. Physical And Chemical Evaluation Of Chocolate Cake Covered With Gelatin, Stearic Acid, Modified Starch Or "carnaúba" Wax Edible Icing [avaliação Físico-química De Bolo De Chocolate Com Coberturas Comestíveis à Base De Gelatina, ácido Esteárico, Amido Modificado Ou Cera De Carnaúba

    OpenAIRE

    Osawa C.C.; Fontes L.C.B.; Miranda E.H.W.; Chang Y.K.; Steel C.J.

    2009-01-01

    Biodegradable edible icing or frosting is an alternative to synthetic packaging that causes environmental concerns. This work evaluated the effect of different types of frosting on the physical-chemical properties of chocolate cake during storage in comparison to cakes without icing or frosting (C) and cakes without frosting packed in polypropylene (CP). The following frostings were applied to the cakes: 10% gelatin (GE), 10% gelatin with 10% stearic acid (GE+SA), 18% "carnaúba" wax (CW), 10%...

  6. CHEMICALS

    CERN Document Server

    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

  7. Direct proteins electrochemistry based on ionic liquid mediated carbon nanotube modified glassy carbon electrode.

    Science.gov (United States)

    Zhao, Qiang; Zhan, Dongping; Ma, Hongyang; Zhang, Meiqin; Zhao, Yifang; Jing, Ping; Zhu, Zhiwei; Wan, Xinhua; Shao, Yuanhua; Zhuang, Qiankun

    2005-01-01

    A novel glassy carbon electrode modified by a gel containing multi-walled carbon nanotubes (MWNTs) and ionic liquid of 1-butyl-3-methylimidazolium hexafluorophosphate (BMIPF6) is reported. The gel is formed by grinding of MWNTs and BMIPF6. Such gel is then coated on the surface of a glassy carbon electrode. We have employed scanning electron microscopy, Fourier transform infrared spectrometry (FTIR) and cyclic voltammetry to characterize the modified electrode. The direct electron transfers of hemoglobin and catalase on the modified electrode have been observed and studied in detail electrochemically. Hemoglobin is verified to be adsorbed on the modified electrode with the retention of conformation, which has been proved by microscopic FTIR. The electrochemical response of the adsorbed hemoglobin on the modified electrode is very stable, and shows repeated changes in the different pH solutions. It also has shown electrocatalysis to the reduction of oxygen and trichloroacetic acid. Catalase adsorbed on the gel modified electrode still keep activity to hydrogen peroxide. This work provides a simple and easy approach to construct biosensors based on the carbon nanotubes and ionic liquids.

  8. Extracellular biosynthesis of gadolinium oxide (Gd2O3) nanoparticles, their biodistribution and bioconjugation with the chemically modified anticancer drug taxol

    OpenAIRE

    Khan, Shadab Ali; Gambhir, Sanjay; Ahmad, Absar

    2014-01-01

    As a part of our programme to develop nanobioconjugates for the treatment of cancer, we first synthesized extracellular, protein-capped, highly stable and well-dispersed gadolinium oxide (Gd2O3) nanoparticles by using thermophilic fungus Humicola sp. The biodistribution of the nanoparticles in rats was checked by radiolabelling with Tc-99m. Finally, these nanoparticles were bioconjugated with the chemically modified anticancer drug taxol with the aim of characterizing the role of this bioconj...

  9. Synthesis of chemically-modified single-walled carbon nanotubes by counter-current ammonia gas injection into the induction thermal plasma process

    Science.gov (United States)

    Shahverdi, Ali

    Pristine single-walled carbon nanotubes (SWCNTs) are poorly dispersible and insoluble in many solvents and need to be chemically modified prior to their use in many applications. This work is focused on the investigation of the synthesis of chemically modified SWCNTs material through an in situ approach. The main objectives of the presented research are: 1) to explore the in situ chemical process during the synthesis of SWCNT and 2) to closely examine the effect of a reactive environment on SWCNTs. Effects of the catalyst type and content on the SWCNTs final product, synthesized by induction thermal plasma (ITP), were studied to replace toxic cobalt (Co) in the feedstock. In this regard, three different catalyst mixtures (i.e. Ni-Y2O3, Ni-Co-Y2O3, and Ni-Mo-Y2O3) were used. Experimental results showed that the catalyst type affects the quality of the SWCNT final product. Similar quality SWCNTs can be produced when the same amount of Co was replaced by Ni. Moreover, the results observed in this experimental work were further explained by thermodynamic calculation results. Thermogravimetry (TG) was used throughout the work to characterize the SWCNTs product. TG was firstly standardized by studying the effects of three main instrumental parameters (temperature ramp, TR, initial mass of the sample, IM, and gas flow rate, FR) on the Tonset and full-width half maximum (FWHM) obtained from TG and derivative TG graphs of carbon black, respectively. Therefore, a two-level factorial statistical design was performed. The statistical analysis showed that the effect of TR, IM, and to a lower extent, FR, is significant on FWHM and insignificant on Tonset. A methodology was then developed based upon the SWCNTs synthesis using the ITP system, through an in situ chemistry approach. Ammonia (NH3) was selected and counter-currently injected into the ITP reactor at three different flow rates and by four different nozzle designs. Numerical simulation indicated a better mixing of NH3 in

  10. Effect of modified atmosphere and vacuum packaging on selected chemical parameters of rainbow trout (Oncorhynchus mykiss and carp (Cyprinus carpio cuts freshness

    Directory of Open Access Journals (Sweden)

    Babić Jelena A.

    2014-01-01

    vacuum was established during the whole period of investigation (p < 0,001, while in carp cuts samples packaged in vacuum the increase in pH value (p < 0,05 was established up to 7th day of testing. Based on the obtained results it can be concluded that gas mixture consisting of 60% CO2 and 40% N2 was the most suitable for packaging of fresh trout and carp cuts in terms of selected chemical parameters, such as TVB-N and pH. [Projekat Ministarstva nauke Republike Srbije, br. TR 31011 i br. TR 31075

  11. Chemical reactivity and skin sensitization potential for benzaldehydes: can Schiff base formation explain everything?

    Science.gov (United States)

    Natsch, Andreas; Gfeller, Hans; Haupt, Tina; Brunner, Gerhard

    2012-10-15

    Skin sensitizers chemically modify skin proteins rendering them immunogenic. Sensitizing chemicals have been divided into applicability domains according to their suspected reaction mechanism. The widely accepted Schiff base applicability domain covers aldehydes and ketones, and detailed structure-activity-modeling for this chemical group was presented. While Schiff base formation is the obvious reaction pathway for these chemicals, the in silico work was followed up by limited experimental work. It remains unclear whether hydrolytically labile Schiff bases can form sufficiently stable epitopes to trigger an immune response in the living organism with an excess of water being present. Here, we performed experimental studies on benzaldehydes of highly differing skin sensitization potential. Schiff base formation toward butylamine was evaluated in acetonitrile, and a detailed SAR study is presented. o-Hydroxybenzaldehydes such as salicylaldehyde and the oakmoss allergens atranol and chloratranol have a high propensity to form Schiff bases. The reactivity is highly reduced in p-hydroxy benzaldehydes such as the nonsensitizing vanillin with an intermediate reactivity for p-alkyl and p-methoxy-benzaldehydes. The work was followed up under more physiological conditions in the peptide reactivity assay with a lysine-containing heptapeptide. Under these conditions, Schiff base formation was only observable for the strong sensitizers atranol and chloratranol and for salicylaldehyde. Trapping experiments with NaBH₃CN showed that Schiff base formation occurred under these conditions also for some less sensitizing aldehydes, but the reaction is not favored in the absence of in situ reduction. Surprisingly, the Schiff bases of some weaker sensitizers apparently may react further to form stable peptide adducts. These were identified as the amides between the lysine residues and the corresponding acids. Adduct formation was paralleled by oxidative deamination of the parent

  12. Preparation, Biodegradation of Coconut Oil Driven Chemically Modified Bovine Serum Albumin Microparticles of Encapsulated Cicer arietinum Amylase and Study of Their Application in Washing Detergents

    Directory of Open Access Journals (Sweden)

    Kirti Rani

    2014-10-01

    Full Text Available In present work, Cicer arietinum amylase was encapsulated by emulsification through covalent coupling by glutaraldehyde into chemically modified bovine serum albumin. Biodegradation of coconut oil driven emulsified bovine serum albumin encapsulated Cicer arietinum amylase was carried out by the alkaline protease for its controlled and sustained release of encapsulated enzyme from prepared microparticles of encapsulated Cicer arietinum amylase and its stability increased up to 6 months as compared to free enzyme. Its biodegradation was carried out by the using different concentration of alkaline protease (5U, 10U, 15U, 20U, 25U, 30U, 35U, 40U. Further, this coconut oil driven chemically modified bovine serum albumin microparticles of encapsulated Cicer arietinum amylase with alkaline protease were used with detergents for washing of stained cloths which have rust, gel pen ink, grease and chocolate strains. These chosen strains are very commonly present on uniforms of school going children which are very tough upon drying, hence, not to be easily vanish with well known brand detergents upon in one wash. But, the mixture solution of coconut oil driven chemically modified bovine serum albumin microparticles of encapsulated Cicer arietinum amylase along with alkaline protease were used with detergents powder for washing of these dry tough strains (rust, gel pen ink, grease and chocolate strains leads to vanishing these strains very fast with absolute clear results were found as compared to results of washing of stained cloths with detergents only.

  13. Effect of chemically modified Vulcan XC-72R on the performance of air-breathing cathode in a single-chamber microbial fuel cell.

    Science.gov (United States)

    Duteanu, N; Erable, B; Senthil Kumar, S M; Ghangrekar, M M; Scott, K

    2010-07-01

    The catalytic activity of modified carbon powder (Vulcan XC-72R) for oxygen reduction reaction (ORR) in an air-breathing cathode of a microbial fuel cell (MFC) has been investigated. Chemical modification was carried out by using various chemicals, namely 5% nitric acid, 0.2N phosphoric acid, 0.2N potassium hydroxide and 10% hydrogen peroxide. Electrochemical study was performed for ORR of these modified carbon materials in the buffer solution pH range of 6-7.5 in the anodic compartment. Although, these treatments influenced the surface properties of the carbon material, as evident from the SEM-EDX analysis, treatment with H(2)PO(4), KOH, and H(2)O(2) did not show significant activity during the electrochemical test. The HNO(3) treated Vulcan demonstrated significant ORR activity and when used in the single-chamber MFC cathode, current densities (1115mA/m(2), at 5.6mV) greater than those for a Pt-supported un-treated carbon cathode were achieved. However, the power density for the latter was higher. Such chemically modified carbon material can be a cheaper alternative for expensive platinum catalyst used in MFC cathode construction.

  14. Chemical analyses of hydroxyapatite formation on SAM surfaces modified with COOH, NH(2), CH(3), and OH functions.

    Science.gov (United States)

    Hirata, Isao; Akamatsu, Mai; Fujii, Eri; Poolthong, Suchit; Okazaki, Masayuki

    2010-08-01

    Hydroxyapatite formation was examined at the surface of self-assembled monolayers (SAMs) modified with four functional groups, -COOH, -NH(2), -CH(3), and -OH. For COOH-SAM and NH(2)-SAM, scanning electron spectroscopic observation showed that flake-like sheet crystals covered the whole wafer and small broccoli-like crystals were observed occasionally on the flake-like crystal base layer. For CH(3)-SAM and OH-SAM, no flake-like sheet crystals were observed; broccoli-like crystals were observed in a dispersed manner for CH(3)-SAM, but in localized spots for OH-SAM. X-ray diffraction patterns showed a strong apatite pattern oriented toward the c-axis direction for COOH-SAM. ESCA analysis revealed distinct Ca, P, O peaks for COOH-, NH(2)-, CH(3)-, and OH-SAM. Surface plasmon resonance (SPR) analysis indicated that during the supply of supersaturated calcium phosphate solution, the deposition of precipitates increased monotonically with time for COOH-SAM, increased slightly for NH(2)-SAM, but little increase in deposition was detected for CH(3)-SAM and OH-SAM.

  15. Long-Term Performance of Chemically and Physically Modified Activated Carbons in Air Cathodes of Microbial Fuel Cells

    KAUST Repository

    Zhang, Xiaoyuan

    2014-07-31

    © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. Activated carbon (AC) is a low-cost and effective catalyst for oxygen reduction in air cathodes of microbial fuel cells (MFCs), but its performance must be maintained over time. AC was modified by three methods: 1)pyrolysis with iron ethylenediaminetetraacetic acid (AC-Fe), 2)heat treatment (AC-heat), and 3)mixing with carbon black (AC-CB). The maximum power densities after one month with these AC cathodes were 35% higher with AC-Fe (1410±50mW m-2) and AC-heat (1400±20mW m-2), and 16% higher with AC-CB (1210±30mW m-2) than for plain AC (1040±20mW m-2), versus 1270±50mW m-2 for a Pt control. After 16months, the Pt cathodes produced only 250±10mW m-2. However, the AC-heat and AC-CB cathodes still produced 960-970mW m-2, whereas plain AC produced 860±60mW m-2. The performance of the AC cathodes was restored to >85% of the initial maximum power densities by cleaning with a weak acid solution. Based on cost considerations among the AC materials, AC-CB appears to be the best choice for long-term performance.

  16. Carbon Nanotube Based Chemical Sensors for Space and Terrestrial Applications

    Science.gov (United States)

    Li, Jing; Lu, Yijiang

    2009-01-01

    A nanosensor technology has been developed using nanostructures, such as single walled carbon nanotubes (SWNTs), on a pair of interdigitated electrodes (IDE) processed with a silicon-based microfabrication and micromachining technique. The IDE fingers were fabricated using photolithography and thin film metallization techniques. Both in-situ growth of nanostructure materials and casting of the nanostructure dispersions were used to make chemical sensing devices. These sensors have been exposed to nitrogen dioxide, acetone, benzene, nitrotoluene, chlorine, and ammonia in the concentration range of ppm to ppb at room temperature. The electronic molecular sensing of carbon nanotubes in our sensor platform can be understood by intra- and inter-tube electron modulation in terms of charge transfer mechanisms. As a result of the charge transfer, the conductance of p-type or hole-richer SWNTs in air will change. Due to the large surface area, low surface energy barrier and high thermal and mechanical stability, nanostructured chemical sensors potentially can offer higher sensitivity, lower power consumption and better robustness than the state-of-the-art systems, which make them more attractive for defense and space applications. Combined with MEMS technology, light weight and compact size sensors can be made in wafer scale with low cost. Additionally, a wireless capability of such a sensor chip can be used for networked mobile and fixed-site detection and warning systems for military bases, facilities and battlefield areas.

  17. Photonic crystal fiber based chloride chemical sensors for corrosion monitoring

    Science.gov (United States)

    Wei, Heming; Tao, Chuanyi; Krishnaswamy, Sridhar

    2016-04-01

    Corrosion of steel is one of the most important durability issues in reinforced concrete (RC) structures because aggressive ions such as chloride ions permeate concrete and corrode steel, consequently accelerating the destruction of structures, especially in marine environments. There are many practical methods for corrosion monitoring in RC structures, mostly focusing on electrochemical-based sensors for monitoring the chloride ion which is thought as one of the most important factors resulting in steel corrosion. In this work, we report a fiber-optic chloride chemical sensor based on long period gratings inscribed in a photonic crystal fiber (PCF) with a chloride sensitive thin film. Numerical simulation is performed to determine the characteristics and resonance spectral response versus the refractive indices of the analyte solution flowing through into the holes in the PCF. The effective refractive index of the cladding mode of the LPGs changes with variations of the analyte solution concentration, resulting in a shift of the resonance wavelength, hence providing the sensor signal. This fiber-optic chemical sensor has a fast response, is easy to prepare and is not susceptible to electromagnetic environment, and can therefore be of use for structural health monitoring of RC structures subjected to such aggressive environments.

  18. Dataset on photonic crystal fiber based chemical sensor.

    Science.gov (United States)

    Ahmed, Kawsar; Paul, Bikash Kumar; Chowdhury, Sawrab; Islam, Md Shadidul; Sen, Shuvo; Islam, Md Ibadul; Asaduzzaman, Sayed; Bahar, Ali Newaz; Miah, Mohammad Badrul Alam

    2017-06-01

    This article represents the data set of micro porous core photonic crystal fiber based chemical sensor. The suggested structure is folded cladding porous shaped with circular air hole. Here is investigated four distinctive parameters including relative sensitivity, confinement loss, numerical aperture (NA), and effective area (Aeff). The numerical outcomes are computed over the E+S+C+L+U communication band. The useable sensed chemicals are methanol, ethanol, propanol, butanol, and pentanol whose are lies in the alcohol series (Paul et al., 2017) [1]. Furthermore, V-parameter (V), Marcuse spot size (MSS), and beam divergence (BD) are also investigated rigorously. All examined results have been obtained using finite element method based simulation software COMSOL Multiphysics 4.2 versions with anisotropic circular perfectly matched layer (A-CPML). The proposed PCF shows the high NA from 0.35 to 0.36; the low CL from ~10(-11) to ~10(-7) dB/m; the high Aeff from 5.50 to 5.66 µm(2); the MSS from 1.0 to 1.08 µm; the BD from 0.43 to 0.46 rad at the controlling wavelength λ = 1.55 µm for employing alcohol series respectively.

  19. Dataset on photonic crystal fiber based chemical sensor

    Directory of Open Access Journals (Sweden)

    Kawsar Ahmed

    2017-06-01

    Full Text Available This article represents the data set of micro porous core photonic crystal fiber based chemical sensor. The suggested structure is folded cladding porous shaped with circular air hole. Here is investigated four distinctive parameters including relative sensitivity, confinement loss, numerical aperture (NA, and effective area (Aeff. The numerical outcomes are computed over the E+S+C+L+U communication band. The useable sensed chemicals are methanol, ethanol, propanol, butanol, and pentanol whose are lies in the alcohol series (Paul et al., 2017 [1]. Furthermore, V-parameter (V, Marcuse spot size (MSS, and beam divergence (BD are also investigated rigorously. All examined results have been obtained using finite element method based simulation software COMSOL Multiphysics 4.2 versions with anisotropic circular perfectly matched layer (A-CPML. The proposed PCF shows the high NA from 0.35 to 0.36; the low CL from ~10–11 to ~10−7 dB/m; the high Aeff from 5.50 to 5.66 µm2; the MSS from 1.0 to 1.08 µm; the BD from 0.43 to 0.46 rad at the controlling wavelength λ = 1.55 µm for employing alcohol series respectively.

  20. Systematic Review of School-based Interventions to Modify Dietary Behavior: Does Intervention Intensity Impact Effectiveness?

    Science.gov (United States)

    Racey, Megan; O'Brien, Charlene; Douglas, Sabrina; Marquez, Olivia; Hendrie, Gilly; Newton, Genevieve

    2016-01-01

    Background: Owing to the associations between diet and health, it is important that effective health promotion strategies establish healthful eating behaviors from an early age. We reviewed the intensity of school-based interventions aimed to modify dietary behavior in preadolescent and adolescents and related intervention characteristics to…

  1. A Modified Protocol of Quantum Key Distribution Based on Entanglement Swapping

    Institute of Scientific and Technical Information of China (English)

    HUANG Xin; LI Shu-Min; WANG An-Min

    2007-01-01

    By comparing Cabello's addendum to his quantum key distribution protocol [Phys. Rev. A 64 (2001) 024301],we propose a more convenient modified protocol based on the entanglement swapping which is secure against the eavesdropping strategy addressed by Zhang et al. [Phys. Rev. A 63 (2001)036301] and other existing types of attack.

  2. A new smart additive of reinforced concrete based on modified hydrotalcites: Preparation, characterization and anticorrosion applications

    NARCIS (Netherlands)

    Yang, Z.; Fischer, H.; Polder, R.

    2012-01-01

    A carbonate form of Mg-Al-hydrotalcite and its p-aminobenzoate (pAB) modified derivative (i.e.,Mg(2)Al-pAB) were synthesized and characterized by means of XRD and FT-IR. The anticorrosion behavior was evaluated based on open circuit potential (OCP) of carbon steel in simulated concrete pore solution

  3. Modified multistep method based on interpolation for solving ordinary differential problem

    Science.gov (United States)

    Ismail, Azman; Ahmad, Rokiah@Rozita; Din, Ummul Khair Salma; Hamid, Mohd Rosli A.

    2014-06-01

    This study is based on multistep method using interpolation formula. The coefficients of new formula are produced using modification on interpolation. This method is tested on ordinary differential equations. Comparisons are between the modified method and the classical Adams Bashforth and Adams-Moulton methods with equal step. Mathematica software is used to determine the new coefficients.

  4. Modified third order multistep method based on interpolation for solving ordinary differential problem

    Science.gov (United States)

    Ismail, Azman; Ahmad, Rokiah Rozita; Din, Ummul Khair Salma; Hamid, Mohd Rosli A.

    2014-09-01

    This study is based on third order multistep method using interpolation formula. The coefficients of new formula are produced using modification on interpolation. This method is tested on ordinary differential equations. Comparisons are between the modified method and the classical Adams Bashforth. Mathematica software is used to determine the new coefficients. The methods was found to be efficient when tested on ordinary differential equation.

  5. A Modified Importance-Performance Framework for Evaluating Recreation-Based Experiential Learning Programs

    Science.gov (United States)

    Pitas, Nicholas; Murray, Alison; Olsen, Max; Graefe, Alan

    2017-01-01

    This article describes a modified importance-performance framework for use in evaluation of recreation-based experiential learning programs. Importance-performance analysis (IPA) provides an effective and readily applicable means of evaluating many programs, but the near universal satisfaction associated with recreation inhibits the use of IPA in…

  6. Boronate-Modified Interdigitated Electrode Array for Selective Impedance-Based Sensing of Glycated Hemoglobin

    DEFF Research Database (Denmark)

    Boonyasit, Yuwadee; Laiwattanapaisal, Wanida; Chailapakul, Orawon

    2016-01-01

    An impedance-based label-free affinity sensor was developed for the recognition of glycated hemoglobin (HbA1c). Interdigitated gold microelectrode arrays (IDA) were first modified with a self-assembled monolayer of cysteamine followed by cross-linking with glutaraldehyde and subsequent binding of...

  7. #DDOD Use Case: Make VBM (Value-Based Payment Modifier) reporting for all groups publicly available

    Data.gov (United States)

    U.S. Department of Health & Human Services — SUMMARY DDOD use case request to make Value-Based Payment Modifier (VBM) reporting more transparent for everyone. WHAT IS A USE CASE? A “Use Case” is a request that...

  8. Chemical Abstracts Service approach to management of large data bases.

    Science.gov (United States)

    Huffenberger, M A; Wigington, R L

    1975-02-01

    When information handling is "the business," as it is at Chemical Abstract Service (CAS), the total organization must be involved in information management. Since 1967, when, as a result of long-range planning efforts, CAS adopted a "data-base approach" to management of both the processing system and the distribution of information files, CAS has been grappling with the problems of managing large collections of information in computer-based systems. This paper describes what has been done at CAS in the management of large files and what we see as necessary, as a result of our experience, to improve and complete the information management system that is the foundation of our production processes.

  9. Zirconia-based solid state chemical gas sensors

    CERN Document Server

    Zhuiykov, S

    2000-01-01

    This paper presents an overview of chemical gas sensors, based on solid state technology, that are sensitive to environmental gases, such as O sub 2 , SO sub x , NO sub x , CO sub 2 and hydrocarbons. The paper is focussed on performance of electrochemical gas sensors that are based on zirconia as a solid electrolyte. The paper considers sensor structures and selection of electrode materials. Impact of interfaces on sensor performance is discussed. This paper also provides a brief overview of electrochemical properties of zirconia and their effect on sensor performance. Impact of auxiliary materials on sensors performance characteristics, such as sensitivity, selectivity, response time and recovery time, is also discussed. Dual gas sensors that can be applied for simultaneous monitoring of the concentration of both oxygen and other gas phase components, are briefly considered

  10. Mean kernels to improve gravimetric geoid determination based on modified Stokes's integration

    Science.gov (United States)

    Hirt, C.

    2011-11-01

    Gravimetric geoid computation is often based on modified Stokes's integration, where Stokes's integral is evaluated with some stochastic or deterministic kernel modification. Accurate numerical evaluation of Stokes's integral requires the modified kernel to be integrated across the area of each discretised grid cell (mean kernel). Evaluating the modified kernel at the center of the cell (point kernel) is an approximation, which may result in larger numerical integration errors near the computation point, where the modified kernel exhibits a strongly nonlinear behavior. The present study deals with the computation of whole-of-the-cell mean values of modified kernels, exemplified here with the Featherstone-Evans-Olliver (1998) kernel modification [Featherstone, W.E., Evans, J.D., Olliver, J.G., 1998. A Meissl-modified Vaníček and Kleusberg kernel to reduce the truncation error in gravimetric geoid computations. Journal of Geodesy 72(3), 154-160]. We investigate two approaches (analytical and numerical integration), which are capable of providing accurate mean kernels. The analytical integration approach is based on kernel weighting factors which are used for the conversion of point to mean kernels. For the efficient numerical integration, Gauss-Legendre quadrature is applied. The comparison of mean kernels from both approaches shows a satisfactory mutual agreement at the level of 10 -4 and better, which is considered to be sufficient for practical geoid computation requirements. Closed-loop tests based on the EGM2008 geopotential model demonstrate that using mean instead of point kernels reduces numerical integration errors by ˜65%. The use of mean kernels is recommended in remove-compute-restore geoid determination with the Featherstone-Evans-Olliver (1998) kernel or any other kernel modification under the condition that the kernel changes rapidly across the cells in the neighborhood of the computation point.

  11. Study on Tribological Behaviors of Boron-Nitrogen Modified Fatty Acid as Water-Based Lube Additives

    Institute of Scientific and Technical Information of China (English)

    FANG Jian-hua; CHEN Bo-shui; DONG Ling; WANG Jiu

    2008-01-01

    A new type of boron-nitrogen modified fatty acid as water base lube additive was prepared and the chemical structure characterized by infrared spectrum. The tribological properties of the additive in water were evaluated by friction testers. The morphographies and tribochemical species of the worn surfaces were analyzed by means of X-ray Photoelectron Spectroscope (XPS). The results showed that the additive is excellent in increasing loadcarrying capacity, anti-wear and friction-reducing abilities of water. The lubrication mechanism is inferred that a high strength adsorption film and a tribochemical reaction film are formed on the rubbing surfaces due to the carrier effect of the long chain fatty acid molecules, high reaction activities of nitrogen, electron-deficient orbit of boron and their synergisms.

  12. Selective separation of mercury(II) using magnetic chitosan resin modified with Schiff's base derived from thiourea and glutaraldehyde.

    Science.gov (United States)

    Donia, Ahmed M; Atia, Asem A; Elwakeel, Khalid Z

    2008-03-01

    Magnetic chitosan resin was chemically modified by a Schiff's base cross-linker. The interaction of the resin obtained with Hg(II) was studied and uptake value of 2.8 mmol/g was reported. The kinetic and thermodynamic parameters of the adsorption process were estimated. These data indicated that the adsorption process is exothermic and follow the pseudo-second-order kinetics. The selectivity of Hg(II) from other different metal ions in solutions using the studied resin was also reported. Breakthrough curves for the recovery of Hg(II) were studied. The critical bed height was found to be 2.05 cm. The adsorbed Hg(II) was eluted from the resin effectively using 0.1 M potassium iodide.

  13. A Modified Decision Based Mean Median Algorithm for Removal of High Density Salt and Pepper Noise

    Directory of Open Access Journals (Sweden)

    Jitender Kumar

    2014-03-01

    Full Text Available This paper presents a modified decision based mean median filter for removal of salt and pepper noise in gray scale images. This is a computationally efficient filtering technique. It is implemented in two steps: In the first step, noisy pixels are identified and in the second step, the proposed algorithm is applied only on noisy pixels. The noise free pixels are not modified, which helps in retaining the image features. Experimental results show that the proposed algorithm performs better than various recent denoising methods in terms of PSNR, IEF and MSE.

  14. Development of a DNA Sensor Based on Alkanethiol Self- Assembled Monolayer-Modified Electrodes

    Directory of Open Access Journals (Sweden)

    José M. Pingarrón

    2005-11-01

    Full Text Available An electrochemical DNA biosensor based on recognition of double or singlestranded DNA (ds-DNA/ss-DNA immobilised on a self-assembled modified gold electrodeis presented for denaturalisation and hybridisation detection. DNA is covalently bond on aself assembled 3-mercaptopropionic acid monolayer by using water soluble N-3-(dimethylaminopropyl-N´ethylcarbodiimide hydrochloride (EDC and Nhydroxisulfosuccinimide(NHSS as linkers. The interaction between the immobilised DNAand methylene blue (MB is investigated using square wave voltammetry (SWV. Theincrease or diminution of peak currents of the MB upon the hybridisation or denaturalisationevent at the modified electrode surface is studied.

  15. Multi-face detection based on downsampling and modified subtractive clustering for color images

    Institute of Scientific and Technical Information of China (English)

    KONG Wan-zeng; ZHU Shan-an

    2007-01-01

    This paper presents a multi-face detection method for color images. The method is based on the assumption that faces are well separated from the background by skin color detection. These faces can be located by the proposed method which modifies the subtractive clustering. The modified clustering algorithm proposes a new definition of distance for multi-face detection, and its key parameters can be predetermined adaptively by statistical information of face objects in the image. Downsampling is employed to reduce the computation of clustering and speed up the process of the proposed method. The effectiveness of the proposed method is illustrated by three experiments.

  16. Properties of unidirectional GFRPs based on an epoxy resin modified with polysulphone or an epoxyurethane oligomer

    Science.gov (United States)

    Solodilov, V. I.; Gorbatkina, Yu. A.

    2006-11-01

    The mechanical properties of unidirectional GFRPs based on an ED-22 epoxy resin were investigated. The resin was modified with a PSK-1 polysulphone or a PEF-3a epoxyurethane oligomer. Triethanolaminotitanate or diaminodiphenilsulphone was used as a hardener. The modification did not improve the mechanical properties of GFRPs in quasi-static loading; but in a low-speed impact loading, the shear strength of epoxypolysulphone GFRPs with 20 wt.% PSK-1 increased by 20-25%. For all the GFRPs investigated, the shear strength grew linearly with the logarithm of loading rate. The introduction of the modifiers increased the fracture toughness considerably: by 100 and 70% for GFRPs modified with 20 wt.% PSK-1 and 50 wt.% PEF-3a, respectively.

  17. Biodegradable polyester-based eco-composites containing hemp fibers modified with macrocyclic oligomers

    Science.gov (United States)

    Conzatti, Lucia; Utzeri, Roberto; Hodge, Philip; Stagnaro, Paola

    2016-05-01

    An original compatibilizing pathway for hemp fibers/poly(1,4-butylene adipate-co-terephtalate) (PBAT) eco-composites was explored exploiting the capability of macrocyclic oligomers (MCOs), obtained by cyclodepolymerization (CDP) of PBAT at high dilution, of being re-converted into linear chains by entropically-driven ring-opening polymerization (ED-ROP) that occurs simply heating the MCOS in the bulk. CDP reaction of PBAT was carried out varying solvent, catalyst and reaction time. Selected MCOs were used to adjust the conditions of the ED-ROP reaction. The best experimental conditions were then adopted to modify hemp fibers. Eco-composites based on PBAT and hemp fibers as obtained or modified with PBAT macrocyclics or oligomers were prepared by different process strategies. The best fiber-PBAT compatibility was observed when the fibers were modified with PBAT oligomers before incorporation in the polyester matrix.

  18. High-performance lubricant additives based on modified graphene oxide by ionic liquids.

    Science.gov (United States)

    Fan, Xiaoqiang; Wang, Liping

    2015-08-15

    Graphene oxide (GO) is a layered material bearing a variety of oxygen-containing functional groups on its basal planes and edges, which allow it as a substrate to conduct a variety of chemical transformations. Here modified graphene oxide (MGO) was prepared using alkyl imidazolium ionic liquids (ILs) (1-butyl-3-methylimidazolium tetrafluoroborate (LB104), 1-butyl-3-methyl imidazolium hexafluorophosphate (LP104) and 1-hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl) amide (LF106)) via epoxide ring-opening reaction, cation-π stacking or van der Waals interactions, with LB104 modified graphene (MG) exfoliated from graphite rod by a moderate electrochemical method as a comparison. The stability and tribological properties of MGO and MG as multialkylated cyclopentanes (MACs) additives were investigated in detail. The results show that GO is converted into graphene through the chemical modification using ILs, and MGO with good dispersion and stability in MACs significantly improves the tribological performance (friction and wear were reduced about 27% and 74% with pure MACs as a comparison, respectively). The excellent tribological properties are attributed to the formation of an ILs-containing graphene-rich tribofilm on the sliding surfaces, which as the third body can prevent the sliding surfaces from straight asperity contact and improve friction reducing and anti-wear behaviors.

  19. Template-free TiO2 photoanodes for dye-sensitized solar cell via modified chemical route.

    Science.gov (United States)

    Gaikwad, M A; Mane, A A; Desai, S P; Moholkar, A V

    2017-02-15

    Surfactant and template-free Titanium dioxide (TiO2) spheres have been deposited via ultrasonic rinsing assisted modified successive ionic layer adsorption and reaction (M-SILAR) method. The effect of M-SILAR cycle variation on the growth of TiO2 films and power conversion efficiency (PCE) of dye-sensitized solar cells (DSSCs) has been reported. Also, the significant influence of the dye adsorption time of photoelectrodes on the overall PCE of TiO2 based DSSCs has been investigated systematically. The SEM images reveal that the TiO2 microspheres are made up of densely packed and interconnected nanospheres. After dye loading maximum absorption peak around 500nm is seen with broader coverage in the visible region of the solar spectrum. The excess amount of dye for dye loading time 15h did not contribute to current and is suspected to be present either in multilayers or physisorbed on the surface of TiO2. The DSSC prepared using photoelectrode TO125 and dye loading time of 12h exhibited the highest power conversion efficiency (PCE) of 1.16% with short-circuit current density (Jsc) of 8.17mA/cm(2), open circuit voltage (Voc) of 0.42V and fill factor of 0.34. The PCE is attributed to the large molecular interconnected TiO2 spheres diffusing visible light to enhance the light absorption. Also, it possesses relatively superior 3-D microsphere like structure and thus provides the effective pathway to the photogenerated electrons with low recombination rate, leading to attaining the high PCE.

  20. Determination of Atropine Sulfate in Human Urines by Capillary Electrophoresis Using Chemical Modified Electrode as Electrochemiluminescence Sensor

    Directory of Open Access Journals (Sweden)

    Min Zhou

    2011-01-01

    Full Text Available A Ru(bpy3 2+-based electrochemiluminescence (ECL detection coupled with capillary electrophoresis (CE was developed for the determination of atropine sulfate on the basis of an Eu-PB modified platinum electrode as the working electrode. The analyte was injected to separation capillary of 50 cm length (25 μm i.d., 360 μm o.d. by electrokinetic injection for 10 s at 10 kV. Parameters related to the separation and detection were discussed and optimized. It was proved that 10 mM phosphate buffer at pH 8.0 could achieve the most favorable resolution, and the high sensitivity of detection was obtained by using the detection potential at 1.15 V and 5 mM Ru(bpy3 2+ in 80 mM phosphate buffer at pH 8.0 in the detection reservoir. Under the optimized conditions, the ECL peak area was in proportion to atropine sulfate concentration in the range from 0.08 to 20 μg⋅mL−1 with a detection limit of 50 ng⋅mL−1 (3σ. The relative standard derivations of migration time and peak area were 0.81 and 3.19%, respectively. The developed method was successfully applied to determine the levels of atropine sulfate in urine samples of patients with recoveries between 90.9 and 98.6%.

  1. INFLUENCE OF PACKAGING MATERIAL AND STORAGE TIME ON PHYSICAL, CHEMICAL AND MICROBIOLOGICAL PROPERTIES OF SET YOGURT: A COMPARATIVE STUDY BETWEEN MODIFIED BIODEGRADABLE POLY(LACTIC ACID AND POLYPROPYLENE

    Directory of Open Access Journals (Sweden)

    NAWADON PETCHWATTANA

    2016-10-01

    Full Text Available The current paper investigates the influence of storage time and type of polymeric packaging material on the chemical, physical and microbiological properties of set yogurt. Firstly, poly(lactic acid (PLA was modified by using a core-shell rubber (CSR and an acrylic processing aid (PA to produce PLA with high toughness and good processability. Secondly, an appropriate PLA/PA/CSR composition was selected and fabricated to yogurt cup. The yogurt was stored in both modified PLA and polypropylene (PP packages to observe some physical, chemical and biological changes. Finally, the biodegradation test was made on both packages and compared with that cellulose. Experimental results revealed that adding 5wt% CSR gave PLA/PA as tough as PP. Types of packaging material and storage time did not change the color of yogurt. The number of lactic acid bacteria grew significantly after they had been incubated for 6 days. The bacterial viability decreased dramatically due to the increased acidity and the decreased pH. A positive impact on the viability of bacterial growth was found when yogurt was stored in modified PLA package. This made yogurt had more health benefits than stored in PP package. The biodegradation test results indicated that the modified PLA degraded at a rapid rate. It achieved approximately 50% biodegradation within 40 days which was comparable to the time required to degrade the cellulose, whereas PP was non-biodegradable over the period studied. In summary, substitution conventional PP by a novel modified PLA seems to be a better way for both the health and the environment benefits.

  2. Electrochemical sensor for Isoniazid based on the glassy carbon electrode modified with reduced graphene oxide–Au nanomaterials

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Zhuo, E-mail: guozhuochina@syuct.edu.cn [Department of Materials Science and Engineering, Shenyang University of Chemical Technology, Shenyang 110142 (China); Wang, Ze-yu [Department of Materials Science and Engineering, Shenyang University of Chemical Technology, Shenyang 110142 (China); Wang, Hui-hua, E-mail: hhwang@suda.edu.cn [Shagang School of Iron and Steel, Soochow University, Suzhou 215021 (China); Huang, Guo-qing; Li, Meng-meng [Department of Materials Science and Engineering, Shenyang University of Chemical Technology, Shenyang 110142 (China)

    2015-12-01

    A sensitive electrochemical sensor has been fabricated to detect Isoniazid (INZ) using reduced graphene oxide (RGO) and Au nanocomposites (RGO–Au). RGO–Au nanocomposites were synthesized by a solution-based approach of chemical co-reduction of Au(III) and graphene oxide (GO), and were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Raman spectroscopy, and Fourier transform infrared (FT-IR). The Au nanoparticles separate the RGO sheets in the precipitate and prevent RGO sheets from aggregation upon π–π stacking interactions. RGO–Au nanocomposites were used to modify the glassy carbon electrode (GCE). The electrochemical properties of RGO–Au/GCE were investigated by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS), and the RGO–Au/GCE exhibited remarkably strong electrocatalytic activities towards INZ. Under the optimized conditions, there was linear relationships between the peak currents and the concentrations in the range of 1.0 × 10{sup −7} M to 1.0 × 10{sup −3} M for INZ, with the limit of detection (LOD) (based on S/N = 3) of 1.0 × 10{sup −8} M for INZ. - Highlights: • RGO–Au nanocomposites were synthesized and characterized by chemical co-reduction of Au (III) and GO. • RGO–Au/GCE was used as a sensitive electrochemical sensor to detect Isoniazid. • RGO–Au/GCE exhibited strong electrocatalytic activities towards Isoniazid.

  3. Chemical Imaging of Platinum-Based Drugs and their Metabolites.

    Science.gov (United States)

    Liu, Xin; Hummon, Amanda B

    2016-12-05

    Platinum-based drugs (cisplatin, carboplatin, and oxaliplatin) are widely used therapeutic agents for cancer treatment. Even though the platinum (Pt)-drugs are routinely used clinically, a clear picture of their distribution within tumor tissues is lacking. The current methods to image the distribution of Pt drugs are limited and do not enable the discrimination of the drug from its metabolites. In this manuscript, we demonstrate a methodology that enables chemical imaging of a Pt drug and its metabolites simultaneously and specifically. Matrix-Assisted Laser Desorption/Ionization (MALDI) Mass Spectrometry Imaging (MSI) is combined with an on-tissue chemical derivatization using diethyldithiocarbamate (DDTC). DDTC abstracts the Pt atom to generate ionizable complexes that can be imaged by MALDI MSI. We demonstrate that Pt drugs and their metabolites can be specifically imaged. This approach was successfully applied to map the penetration and metabolism of oxaliplatin in hyperthermic intraperitoneal chemotherapy (HIPEC)-like treated 3D colorectal tumor mimics. The distribution of cisplatin and carboplatin was mapped in additional 3D tumor mimics. We demonstrate that the approach can also be used to image the distribution of copper ions in cells. This method has the potential to be used to evaluate the penetration and distribution of a wide range of compounds.

  4. Oligo(ethylene glycol)-modified β-cyclodextrin-based polyrotaxanes for simultaneously modulating solubility and cellular internalization efficiency.

    Science.gov (United States)

    Tamura, Atsushi; Ohashi, Moe; Yui, Nobuhiko

    We developed stimuli-labile polyrotaxanes (PRXs) composed of β-cyclodextrin (β-CD), Pluronic as an axle polymer, and acid-cleavable N-triphenylmethyl groups as bulky stopper molecules, and found that the PRXs are potent therapeutics for Niemann-Pick type C disease, because the PRX can effectively reduce intracellular cholesterol through the intracellular release of threaded β-CDs. In general, the PRXs need to be chemically modified with hydrophilic functional groups because PRXs are not soluble in aqueous media. Herein, four series of oligo(ethylene glycol)s (OEGs) with different ethylene glycol repeating unit (2 or 3) and chemical structure of OEG terminal (hydroxy or methoxy) were modified onto the threaded β-CDs in PRX. The effects of the structure of OEG on the aqueous solubility, toxicity, and cellular internalization efficiency of OEG-modified PRXs were investigated to optimize the chemical structure of OEG. The hydroxy-terminated OEG-modified PRXs showed excellent solubility in aqueous media and no toxicity, regardless of the number of ethylene glycol repeating units. In the case of the methoxy-terminated OEG-modified PRXs, sufficient solubility in aqueous media and negligible toxicity were observed when the number of ethylene glycol repeating units was 3, while low solubility and toxicity were observed when the ethylene glycol repeating unit was 2. Additionally, cellular uptake levels of methoxy-terminated OEG-modified PRXs in RAW264.7 cells were higher than those of hydroxy-terminated OEG-modified PRXs. Consequently, the chemical structure of the OEG strongly affects the chemical and biological properties of the PRXs, and that a methoxy-terminated OEG with 3 ethylene glycol repeating units is the most preferable modification of PRXs, since the resultant PRX is sufficiently soluble in aqueous media, non-toxic, and possesses high cellular internalization efficiency.

  5. Computing of network tenacity based on modified binary particle swarm optimization algorithm

    Science.gov (United States)

    Shen, Maoxing; Sun, Chengyu

    2017-05-01

    For rapid calculation of network node tenacity, which can depict the invulnerability performance of network, this paper designs a computational method based on modified binary particle swarm optimization (BPSO) algorithm. Firstly, to improve the astringency of the BPSO algorithm, the algorithm adopted an improved bit transfer probability function and location updating formula. Secondly, algorithm for fitness function value of BPSO based on the breadth-first search is designed. Thirdly, the computing method for network tenacity based on the modified BPSO algorithm is presented. Results of experiment conducted in the Advanced Research Project Agency (ARPA) network and Tactical Support Communication (TCS) network illustrate that the computing method is impactful and high-performance to calculate network tenacity.

  6. A glucose/O{sub 2} biofuel cell base on nanographene platelet-modified electrodes

    Energy Technology Data Exchange (ETDEWEB)

    Zheng, W.; Zhao, H.Y.; Zhang, J.X.; Zhou, H.M.; Xu, X.X. [Center for Biomedical Materials and Engineering, Harbin Engineering University, Harbin 150001 (China); Zheng, Y.F.; Wang, Y.B.; Cheng, Y. [Center for Biomedical Materials and Tissue Engineering, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing 100871 (China); Jang, B.Z. [College of Engineering and Computer Science, Wright State University, 3640 Colonel Glenn Hwy., Dayton, OH 45435 (United States)

    2010-07-15

    This study demonstrated a novel nanographene platelets (NGPs)-based glucose/O{sub 2} biofuel cell (BFC) with the glucose oxidase (GOD) as the anodic biocatalysts and the laccase as the cathodic biocatalysts. The GOD/NGPs-modified electrode exhibited good catalytic activity towards glucose oxidation and the laccase/NGPs-modified electrode exhibited good catalytic activity towards O{sub 2} electroreduction. The maximum power density was ca. 57.8 {mu}W cm{sup -} {sup 2} for the assembled glucose/O{sub 2} NGPs-based BFC. These results indicated that the NGPs were very useful for the future development of novel carbon-based nanomaterials BFC device. (author)

  7. Chemical sensors based on surface-confined dendrimers

    Energy Technology Data Exchange (ETDEWEB)

    Tokuhisa, Hideo; Crooks, R.M. [Texas A& M Univ., College Station, TX (United States). Dept. of Chemistry; Ricco, A.J.; Osbourn, G.C. [Sandia National Labs., Albuquerque, NM (United States)

    1997-10-01

    The use of dendrimers for preparing chemically sensitive interfaces for detecting volatile organic compounds (VOCs) using surface acoustic wave (SAW) device transducers is described. Specifically, the synthesis of the dendrimers and the means by which they are affixed to SAW devices is discussed, followed by a detailed spectroscopic analysis of the surface-confined dendrimers and a discussion of their interaction with different VOCs. Most of these preliminary experiments focus on dendrimer surface modification using benzoylchloride, which leads to phenyl terminal groups linked to the dendrimer via amide groups. The results of this study lead us to conclude that dendrimers: (1) provide general specificity towards classes of functional groups and are therefore suitable for array-based sensing schemes; (2) are intermediate in structure between monolayers and polymers and exhibit the desirable properties of both; (3) can be straightforwardly attached to the surfaces of acoustic wave devices.

  8. Evaluation of Artificial Intelligence Based Models for Chemical Biodegradability Prediction

    Directory of Open Access Journals (Sweden)

    Aleksandar Sabljic

    2004-12-01

    Full Text Available This study presents a review of biodegradability modeling efforts including a detailed assessment of two models developed using an artificial intelligence based methodology. Validation results for these models using an independent, quality reviewed database, demonstrate that the models perform well when compared to another commonly used biodegradability model, against the same data. The ability of models induced by an artificial intelligence methodology to accommodate complex interactions in detailed systems, and the demonstrated reliability of the approach evaluated by this study, indicate that the methodology may have application in broadening the scope of biodegradability models. Given adequate data for biodegradability of chemicals under environmental conditions, this may allow for the development of future models that include such things as surface interface impacts on biodegradability for example.

  9. Theoretical Insights into Three Types of Oxidized Starch-Based Adhesives: Chemical Stability, Water Resistance, and Shearing Viscosity from a Molecular Viewpoint

    Directory of Open Access Journals (Sweden)

    Liang Junxi

    2016-01-01

    Full Text Available To better understand the origin and difference associated with chemical stability, water resistance, and shearing viscosity of three types of different oxidized modified starch-based adhesives, a detailed theoretical investigation from a molecular viewpoint has been performed using the AM1 semiempirical level and the DFT-B3LYP level, respectively. As a result, our findings suggest that, by Mulliken population analysis (MPA, frontier orbital analysis, and electrostatic potential (EP analysis based on B3LYP/6-31G calculations, the chemical stability, water resistance, and shearing viscosity of the oxidized modified starch-based adhesives are uniformly improved and corresponding difference for each property presents an identical order: the oxidized grafted cross-linked starch-based adhesive > the oxidized grafted starch-based adhesive > the oxidized starch-based adhesive, which is well consistent with experimental results.

  10. Trends in information theory-based chemical structure codification.

    Science.gov (United States)

    Barigye, Stephen J; Marrero-Ponce, Yovani; Pérez-Giménez, Facundo; Bonchev, Danail

    2014-08-01

    This report offers a chronological review of the most relevant applications of information theory in the codification of chemical structure information, through the so-called information indices. Basically, these are derived from the analysis of the statistical patterns of molecular structure representations, which include primitive global chemical formulae, chemical graphs, or matrix representations. Finally, new approaches that attempt to go "back to the roots" of information theory, in order to integrate other information-theoretic measures in chemical structure coding are discussed.

  11. Enzymatically hydrolysed, acetylated and dually modified corn starch: physico-chemical, rheological and nutritional properties and effects on cake quality.

    Science.gov (United States)

    Sahnoun, Mouna; Ismail, Nouha; Kammoun, Radhouane

    2016-01-01

    Corn starch was treated by enzymatic hydrolysis with Aspergillus oryzae S2 α-amylase, acetylation with vinyl acetate, and dual modification. The dual modified starch displayed a higher substitution degree than the acetylated starch and lower reducing sugar content than the hydrolysed starch. The results revealed that the cooling viscosity and amylose content of those products decrease (P cake formulations at 5 and 10 % concentrations on a wheat flour basis and compared to native starch. The results revealed that when applied at 5 % concentrations, the modified starches reduced the hardness, cohesion, adhesion and chewiness of baked cakes and enhanced their elasticity, volume, height, crust color, and appearance as compared to native starch. These effects were more pronounced for the cake incorporating the dually modified starch.

  12. Efficient Inverted Organic Solar Cells Based on a Fullerene Derivative-Modified Transparent Cathode.

    Science.gov (United States)

    Wang, Yifan; Cong, Hailin; Yu, Bing; Zhang, Zhiguo; Zhan, Xiaowei

    2017-09-11

    Indium tin oxide (ITO) is a transparent conductive material which is extensively used in organic solar cells (OSCs) as electrodes. In inverted OSCs, ITO is usually employed as a cathode, which should be modified by cathode buffer layers (CBLs) to achieve better contact with the active layers. In this paper, an amine group functionalized fullerene derivative (DMAPA-C60) is used as a CBL to modify the transparent cathode ITO in inverted OSCs based on PTB7 as a donor and PC71BM as an acceptor. Compared with traditional ZnO CBL, DMAPA-C60 exhibited comparable transmittance. OSCs based on DMAPA-C60 show much better device performance compared with their ZnO counterparts (power conversion efficiencies (PCEs) improved from 6.24 to 7.43%). This is mainly because a better contact between the DMAPA-C60 modified ITO and the active layer is formed, which leads to better electron transport and collection. Nanoscale morphologies also demonstrate that the surface of DMAPA-C60-modified ITO is plainer than the ZnO counterparts, which also leads to the better device performance.

  13. Reducing composite restoration polymerization shrinkage stress through resin modified glass-ionomer based adhesives.

    Science.gov (United States)

    Naoum, S J; Mutzelburg, P R; Shumack, T G; Thode, Djg; Martin, F E; Ellakwa, A E

    2015-12-01

    The aim of this study was to determine whether employing resin modified glass-ionomer based adhesives can reduce polymerization contraction stress generated at the interface of restorative composite adhesive systems. Five resin based adhesives (G Bond, Optibond-All-in-One, Optibond-Solo, Optibond-XTR and Scotchbond-Universal) and two resin modified glass-ionomer based adhesives (Riva Bond-LC, Fuji Bond-LC) were analysed. Each adhesive was applied to bond restorative composite Filtek-Z250 to opposing acrylic rods secured within a universal testing machine. Stress developed at the interface of each adhesive-restorative composite system (n = 5) was calculated at 5-minute intervals over 6 hours. The resin based adhesive-restorative composite systems (RBA-RCS) demonstrated similar interface stress profiles over 6 hours; initial rapid contraction stress development (0-300 seconds) followed by continued contraction stress development ≤0.02MPa/s (300 seconds - 6 hours). The interface stress profile of the resin modified glass-ionomer based adhesive-restorative composite systems (RMGIBA-RCS) differed substantially to the RBA-RCS in several ways. Firstly, during 0-300 seconds the rate of contraction stress development at the interface of the RMGIBA-RCS was significantly (p resin modified glass-ionomer based adhesives can significantly reduce the magnitude and rate of polymerization contraction stress developed at the interface of adhesive-restorative composite systems. © 2015 Australian Dental Association.

  14. Evidence-Based Approaches to Improving Chemical Equilibrium Instruction

    Science.gov (United States)

    Davenport, Jodi L.; Leinhardt, Gaea; Greeno, James; Koedinger, Kenneth; Klahr, David; Karabinos, Michael; Yaron, David J.

    2014-01-01

    Two suggestions for instruction in chemical equilibrium are presented, along with the evidence that supports these suggestions. The first is to use diagrams to connect chemical reactions to the effects of reactions on concentrations. The second is the use of the majority and minority species (M&M) strategy to analyze chemical equilibrium…

  15. Incorporating a Modified Problem-Based Learning Exercise in a Traditional Lecture and Lab-Based Dairy Products Course

    Science.gov (United States)

    Liceaga, Andrea M.; Ballard, Tameshia S.; Skura, Brent J.

    2011-01-01

    A modified problem-based learning (PBL) exercise was implemented in a food science Dairy Products course, which had previously been taught in the traditional lecture and laboratory format only. The first 10 wk of the course consisted of weekly lectures and laboratory exercises. During the remaining 3 wk, students were presented with a case study…

  16. Study of Aerosol Chemical Composition Based on Aerosol Optical Properties

    Science.gov (United States)

    Berry, Austin; Aryal, Rudra

    2015-03-01

    We investigated the variation of aerosol absorption optical properties obtained from the CIMEL Sun-Photometer measurements over three years (2012-2014) at three AERONET sites GSFC; MD Science_Center and Tudor Hill, Bermuda. These sites were chosen based on the availability of data and locations that can receive different types of aerosols from land and ocean. These absorption properties, mainly the aerosol absorption angstrom exponent, were analyzed to examine the corresponding aerosol chemical composition. We observed that the retrieved absorption angstrom exponents over the two sites, GSFC and MD Science Center, are near 1 (the theoretical value for black carbon) and with low single scattering albedo values during summer seasons indicating presence of black carbon. Strong variability of aerosol absorption properties were observed over Tudor Hill and will be analyzed based on the air mass embedded from ocean side and land side. We will also present the seasonal variability of these properties based on long-range air mass sources at these three sites. Brent Holben, NASA GSFC, AERONET, Jon Rodriguez.

  17. Total synthesis approaches to natural product derivatives based on the combination of chemical synthesis and metabolic engineering.

    Science.gov (United States)

    Kirschning, Andreas; Taft, Florian; Knobloch, Tobias

    2007-10-21

    Secondary metabolites are an extremely diverse and important group of natural products with industrial and biomedical implications. Advances in metabolic engineering of both native and heterologous secondary metabolite producing organisms have allowed the directed synthesis of desired novel products by exploiting their biosynthetic potentials. Metabolic engineering utilises knowledge of cellular metabolism to alter biosynthetic pathways. An important technique that combines chemical synthesis with metabolic engineering is mutasynthesis (mutational biosynthesis; MBS), which advanced from precursor-directed biosynthesis (PDB). Both techniques are based on the cellular uptake of modified biosynthetic intermediates and their incorporation into complex secondary metabolites. Mutasynthesis utilises genetically engineered organisms in conjunction with feeding of chemically modified intermediates. From a synthetic chemist's point of view the concept of mutasynthesis is highly attractive, as the method combines chemical expertise with Nature's synthetic machinery and thus can be exploited to rapidly create small libraries of secondary metabolites. However, in each case, the method has to be critically compared with semi- and total synthesis in terms of practicability and efficiency. Recent developments in metabolic engineering promise to further broaden the scope of outsourcing chemically demanding steps to biological systems.

  18. Effect of surface modified TiO2 nanoparticles on thermal, barrier and mechanical properties of long oil alkyd resin-based coatings

    Directory of Open Access Journals (Sweden)

    T. S. Radoman

    2015-10-01

    Full Text Available Novel soy alkyd-based nanocomposites (NCs were prepared using TiO2 nanoparticles (NPs surface modified with different gallates, and for the first time with imine obtained from 3,4-dihydroxybenzaldehyde and oleylamine (DHBAOA. Unmodified and surface modified anatase TiO2 NPs were characterized by transmission electron microscopy (TEM, X-ray diffraction (XRD, Fourier transform infrared spectroscopy (FTIR and ultraviolet-visible (UV-Vis spectroscopy, while the amount of adsorbed ligands was calculated from thermogravimetric analysis (TGA results. Surface modification of TiO2 NPs was confirmed by FTIR and UV-Vis spectra. The influence of the TiO2 surface modification on the dispersion of TiO2 NPs in alkyd resin, thermal, barrier and mechanical properties and chemical resistance of alkyd resin/TiO2 NC coatings was investigated. The obtained results revealed that glass transition temperature of all investigated NCs is lower than for pure resin, that the presence of TiO2 NPs surface modified with gallates had no significant influence on the thermooxidative stability of alkyd resin, while TiO2-DHBAOA NPs slightly improved alkyd resin thermooxidative stability. Also, the presence of surface modified TiO2 NPs improved barrier properties, increased stress and strain at break and hardness and chemical resistance and decreased modulus of elasticity and abrasion resistance of alkyd resin.

  19. Fatigue behavior of Ti–6Al–4V alloy in saline solution with the surface modified at a micro- and nanoscale by chemical treatment

    Energy Technology Data Exchange (ETDEWEB)

    Claros, Cesar Adolfo Escobar; Oliveira, Diego Pedreira; Campanelli, Leonardo Contri; Pereira da Silva, Paulo Sergio Carvalho; Bolfarini, Claudemiro

    2016-10-01

    This work evaluated the influence of the surface modification using acid etching combined with alkaline treatment on the fatigue strength of Ti–6Al–4V ELI alloy. The topography developed by chemical surface treatments (CST) was examined by scanning electron microscopy (SEM) and confocal laser scanning microscopy (CLSM). Increased roughness and effective surface area were investigated and compared with the Ti–6Al–4V samples without modification. Surface composition was analyzed by energy dispersive X-ray spectroscopy (EDS). Axial fatigue resistance of polished and modified surfaces was determined by stepwise load increase tests and staircase test method. Light microscopy and SEM were employed to examine the fracture surface of the tested specimens. According to the results, a similar fatigue behavior was found and a negligible difference in the fatigue crack nucleation was observed for the Ti–6Al–4V with CST in comparison to the samples without treatment. - Highlights: • Fatigue behavior of Ti–6Al–4V with the surface modified by chemical treatments • The topography developed did not induce differences in the fatigue resistance. • Untreated and chemically treated surfaces presented fractographic similarities.

  20. Development of Oilfield Chemicals Based on Advantages in Petrochemical Feedstocks

    Institute of Scientific and Technical Information of China (English)

    Wang Xieqing; Peng Pu

    2002-01-01

    This article focuses on the routes for development of oilfield chemicals by making use of the feedstock advantages of the petrochemical industry. The diversification of oilfield chemicals has re sulted in thousand product grades. Because there are hundred domestic producers of oilfield chemicals,mostly medium and small producers, the fluctuations of feedstock prices and product quality cannot be conducive to the application and development of oilfield chemicals. This article illustrates the feasibility of oilfield chemical production by state-run medium and large petrochemical enterprises by allowing full play to their own advantages in petrochemical feedstocks.

  1. A STUDY COMPARING CHEMICAL PEELING USING MODIFIED JESSNER'S SOLUTION AND 15%TRICHLOROACETIC ACID VERSUS 15% TRICHLOROACETIC ACID IN THE TREATMENT OF MELASMA

    Science.gov (United States)

    Safoury, Omar Soliman; Zaki, Nagla Mohamed; El Nabarawy, Eman Ahmad; Farag, Eman Abas

    2009-01-01

    Background: Melasma is a symmetric progressive hyperpigmentation of the facial skin that occurs in all races but has a predilection for darker skin phenotypes. Depigmenting agents, laser and chemical peeling as classic Jessner's solution, modified Jessner's solution and trichloroacetic acid have been used alone and in combination in the treatment of melasma. Objectives: The aim of the study was to compare the therapeutic effect of combined 15% Trichloroacetic acid (TCA) and modified Jessner's solution with 15% TCA on melasma. Materials and Methods: Twenty married females with melasma (epidermal type), with a mean age of 38.25 years, were included in this study. All were of skin type III or IV. Fifteen percent TCA was applied to the whole face, with the exception of the left malar area to which combined TCA 15% and modified Jessner's solution was applied. Results: Our results revealed statistically highly significant difference between MASI Score (Melasma Area and Severity Index) between the right malar area and the left malar area. Conclusion: Modified Jessner's solution proved to be useful as an adjuvant treatment with TCA in the treatment of melasma, improving the results and minimizing postinflammatory hyperpigmentation. PMID:20049268

  2. A study comparing chemical peeling using modified jessner′s solution and 15% trichloroacetic acid versus 15% trichloroacetic acid in the treatment of melasma

    Directory of Open Access Journals (Sweden)

    Safoury Omar

    2009-01-01

    Full Text Available Background: Melasma is a symmetric progressive hyperpigmentation of the facial skin that occurs in all races but has a predilection for darker skin phenotypes. Depigmenting agents, laser and chemical peeling as classic Jessner′s solution, modified Jessner′s solution and trichloroacetic acid have been used alone and in combination in the treatment of melasma. Objectives: The aim of the study was to compare the therapeutic effect of combined 15% Trichloroacetic acid (TCA and modified Jessner′s solution with 15% TCA on melasma. Materials and Methods: Twenty married females with melasma (epidermal type, with a mean age of 38.25 years, were included in this study. All were of skin type III or IV. Fifteen percent TCA was applied to the whole face, with the exception of the left malar area to which combined TCA 15% and modified Jessner′s solution was applied. Results: Our results revealed statistically highly significant difference between MASI Score (Melasma Area and Severity Index between the right malar area and the left malar area. Conclusion: Modified Jessner′s solution proved to be useful as an adjuvant treatment with TCA in the treatment of melasma, improving the results and minimizing postinflammatory hyperpigmentation.

  3. Comparison of Fe-Al-modified natural materials by an electrochemical method and chemical precipitation for the adsorption of F- and As(V).

    Science.gov (United States)

    Vázquez Mejía, G; Martínez-Miranda, V; Fall, C; Linares-Hernández, I; Solache-Ríos, M

    2016-01-01

    The adsorption of fluoride and arsenic ions by modified natural materials may have an impact on the removal of F- and As(V) from waters. In this work, a zeolitic material and pozzolan (commonly known as pumicite) were modified with aluminium an iron by an electrochemical method and chemical precipitation, respectively. The adsorbents were characterized by X-ray diffraction, scanning electron microscopy with energy X-ray disperse spectroscopy analysis and the point of zero charge (pHzpc). F- and As(V) adsorption properties of both materials were investigated. Adsorption kinetic data were best fitted to pseudo-second-order model and equilibrium data to the Langmuir isotherm model. The highest F- and As(V) sorption capacities were obtained for modified zeolitic (0.866 mg/g) and pozzolan (3.35 mg/g) materials, respectively, with initial F- or As(V) concentrations of 10 mg/L. It was found that the unmodified materials did not show either adsorption of F- ions or As(V), which indicated that Al and Fe in the adsorbents are responsible for the adsorption of these ions. In general, both modified materials show similar capacities for the adsorption of F- and As(V).

  4. Development of an aptasensor based on a fluorescent particles-modified aptamer for ochratoxin A detection.

    Science.gov (United States)

    Hayat, Akhtar; Mishra, Rupesh K; Catanante, Gaelle; Marty, Jean Louis

    2015-10-01

    The presented work reports a generic fluorescent aptasensing design employing carboxy-modified fluorescent particles as a signal-generating probe and magnetic particles as a solid separation support. Carboxy-modified fluorescent particles were used to modify the aptamer and act as a signal-generating probe. Magnetic beads were used as an immobilization surface to perform the function of a solid separation support. As a proof of concept, the assay was used to detect ochratoxin A (OTA). Fluorescent detection based on the displacement and competition format was performed, and the obtained results were compared. The competition-based assays were characterized with improved analytical characteristics as compared to those based on the displacement principle. The competitive fluorescent assays showed a high sensitivity where the detection limit and IC50 were 0.005 and 7.2 nM respectively. The aptasensing platform was finally demonstrated for the detection of OTA in a beer sample. However, this is a generic approach that can be very easily extended to other matrixes to determine OTA. Additionally, the proposed concept of fluorescent particles as a signal-generating probe in combination with magnetic particles can also be integrated to other fluorescent-based affinity assays.

  5. Surface Structure and Photocatalytic Properties of Bi2WO6 Nanolatelets Modified by Molybdena Islands from Chemical Vapor Deposition

    NARCIS (Netherlands)

    Dittmer, A.; Menze, J.; Mei, B.T.; Strunk, J.; Luftman, H.S.; Gutkowski, R.; Wachs, I.E.; Schuhmann, W.; Muhler, M.

    2016-01-01

    We report on a novel route of preparing molybdena-modified bismuth tungstates and their successful application in the photocatalytic oxygen evolution reaction and the oxidation of glycerol. Hierarchically assembled monocrystalline Bi2WO6 nanoplatelets with a specific surface area of 10 m2/g were obt

  6. Rheological and chemical evaluation on the ageing properties of SBS polymer modified bitumen: From the laboratory to the field

    NARCIS (Netherlands)

    Liu, G.; Nielsen, E.; Komacka, J.; Greet, L.; Ven, M.V.D.

    2014-01-01

    This study investigated the ageing properties of the styrene-butadiene- styrene polymer modified bitumen (SBS PMB) from the laboratory to the field. The virgin SBS PMB had been kept for 23 years and its field-aged binder was extracted from the reclaimed stone matrix asphalt (SMA) after the 22-year s

  7. Rheological and chemical evaluation on the ageing properties of SBS polymer modified bitumen: From the laboratory to the field

    NARCIS (Netherlands)

    Liu, G.; Nielsen, E.; Komacka, J.; Greet, L.; Ven, M.V.D.

    2014-01-01

    This study investigated the ageing properties of the styrene-butadiene- styrene polymer modified bitumen (SBS PMB) from the laboratory to the field. The virgin SBS PMB had been kept for 23 years and its field-aged binder was extracted from the reclaimed stone matrix asphalt (SMA) after the 22-year

  8. Surface Structure and Photocatalytic Properties of Bi2WO6 Nanolatelets Modified by Molybdena Islands from Chemical Vapor Deposition

    NARCIS (Netherlands)

    Dittmer, A.; Menze, J.; Mei, Bastian Timo; Strunk, J.; Luftman, H.S.; Gutkowski, R.; Wachs, I.E.; Schuhmann, W.; Muhler, M.

    2016-01-01

    We report on a novel route of preparing molybdena-modified bismuth tungstates and their successful application in the photocatalytic oxygen evolution reaction and the oxidation of glycerol. Hierarchically assembled monocrystalline Bi2WO6 nanoplatelets with a specific surface area of 10 m2/g were

  9. Rheological and chemical evaluation on the ageing properties of SBS polymer modified bitumen: From the laboratory to the field

    NARCIS (Netherlands)

    Liu, G.; Nielsen, E.; Komacka, J.; Greet, L.; Ven, M.V.D.

    2014-01-01

    This study investigated the ageing properties of the styrene-butadiene- styrene polymer modified bitumen (SBS PMB) from the laboratory to the field. The virgin SBS PMB had been kept for 23 years and its field-aged binder was extracted from the reclaimed stone matrix asphalt (SMA) after the 22-year s

  10. Chemically modified polymeric resins for separation of cations, organic acids, and small polar moleculea by high performance liquid chromatography

    Energy Technology Data Exchange (ETDEWEB)

    Morris, John B. [Iowa State Univ., Ames, IA (United States)

    1993-07-01

    This thesis is divided into 4 parts: a review, ion chromatography of metal cations on carboxylic resins, separation of hydrophilic organic acids and small polar compounds on macroporous resin columns, and use of eluent modifiers for liquid chromatographic separation of carboxylic acids using conductivity detection.

  11. Enzymatically hydrolysed, acetylated and dually modified corn starch: physico-chemical, rheological and nutritional properties and effects on cake quality

    OpenAIRE

    Sahnoun, Mouna; Ismail, Nouha; Kammoun, Radhouane

    2015-01-01

    Corn starch was treated by enzymatic hydrolysis with Aspergillus oryzae S2 α-amylase, acetylation with vinyl acetate, and dual modification. The dual modified starch displayed a higher substitution degree than the acetylated starch and lower reducing sugar content than the hydrolysed starch. The results revealed that the cooling viscosity and amylose content of those products decrease (P 

  12. Magnetic Flux Leakage Signal Inversion of Corrosive Flaws Based on Modified Genetic Local Search Algorithm

    Institute of Scientific and Technical Information of China (English)

    HAN Wen-hua; FANG Ping; XIA Fei; XUE Fang

    2009-01-01

    In this paper, a modified genetic local search algorithm (MGLSA) is proposed. The proposed algorithm is resulted from employing the simulated annealing technique to regulate the variance of the Gaussian mutation of the genetic local search algorithm (GLSA). Then, an MGLSA-based inverse algorithm is proposed for magnetic flux leakage (MFL) signal inversion of corrosive flaws, in which the MGLSA is used to solve the optimization problem in the MFL inverse problem. Experimental results demonstrate that the MGLSA-based inverse algorithm is more robust than GLSA-based inverse algorithm in the presence of noise in the measured MFL signals.

  13. Voltammetric detection of As(III) with Porphyridium cruentum based modified carbon paste electrode biosensor.

    Science.gov (United States)

    Zaib, M; Saeed, A; Hussain, I; Athar, M M; Iqbal, M

    2014-12-15

    A novel biosensor based on carbon paste electrode modified with Porphyridium cruentum biomass was developed for the determination of As(III) in contaminated water. As(III) was first biosorbed-accumulated on the electrode surface at open circuit potential and then stripped off by applying anodic scan range of -0.8 to +0.8 V using differential pulse anodic stripping voltammetric technique. The best result was obtained at pH 6.0 with 0.1M HNO3 solution as stripping medium, allowing biosorption-accumulation time of 8 min using 5% P. cruentum biomass in graphite-mineral oil paste. Linear range for As(III) detection with the modified electrode-biosensor was observed between 2.5 and 20 µg L(-1). The FTIR spectrum of P. cruentum biomass confirmed the presence of active functional groups that participate in the binding of As(III). Scanning Electron Microscopy (SEM) indulged the surface morphology of modified electrode-biosensor before and after As(III) adsorption. Similarly, Atomic Force Microscopy (AFM) showed that the average roughness of the modified electrode decreased indicating the successful incorporation of P. cruentum biomass. Efficiency of the biosensor in the presence of different interfering metal (Na(+), K(+), Ca(2+), and Mg(2+)) ions were also evaluated. The application of P. cruentum modified biosensor was successfully used for the detection of As(III) in the binary metal (Fe(3+), Mn(2+), Cd(2+), Cu(2+), Ni(2+), Hg(2+), and Pb(2+)) contaminated system. The accuracy of application of biosorption based biosensor for the detection of As(III) is as low as 2.5 µg L(-1).

  14. Evaluation of some vanillin-modified polyoxyethylene surfactants as additives for water based mud

    Directory of Open Access Journals (Sweden)

    M.M.A. El-Sukkary

    2014-03-01

    Full Text Available Water-based drilling fluids are increasingly being used for oil and gas exploration and are generally considered to be more environmentally acceptable than oil-based or synthetic-based fluids. In this study, new types of vanillin-modified polyoxyethylene surfactants were evaluated as additives in water-based mud. Their rheological properties in water-based mud were investigated which included the apparent viscosity, the plastic viscosity, the yield point, the gel strength, the thixotropy as well as the filtration properties. Also, the effect of high temperature on the rheology of the formulated water based mud was studied. The tested ethoxylated non-ionic surfactants showed good results when utilized in the formulation of water-based mud.

  15. Evaluation of chitosan quaternary ammonium salt-modified resin denture base material.

    Science.gov (United States)

    Song, Rong; Zhong, Zhaohua; Lin, Lexun

    2016-04-01

    Chitosan quaternary ammonium salt displays good antioxidant and antibacterial characteristics and it shows appreciable solubility in water. When added to the traditional denture material to form a resin base, it could promote good oral health by improving the oral environment. In this study, chitosan quaternary ammonium salt was added to the denture material following two different methods. After three months of immersion in artificial saliva, the specimens were tested for tensile strength and were scanned by electron microscope. The murine fibroblast cytotoxicity and antibacterial properties were also tested. The result showed no significant differences in the tensile strength and in the proliferation of murine L929 fibroblast cells. The two structures of chitosan quaternary ammonium salt-modified denture material had different degrees of corrosion resistance and antimicrobial properties. These results indicate that chitosan quaternary ammonium salt-modified resin denture base material has the potential to become a new generation oral denture composite material.

  16. EFFICIENT NUMERICAL INTEGRATORS FOR HIGHLY OSCILLATORY DYNAMIC SYSTEMS BASED ON MODIFIED MAGNUS INTEGRATOR METHOD

    Institute of Scientific and Technical Information of China (English)

    LI Wen-cheng; DENG Zi-chen; HUANG Yong-an

    2006-01-01

    Based on the Magnus integrator method established in linear dynamic systems, an efficiently improved modified Magnus integrator method was proposed for the second-order dynamic systems with time-dependent high frequencies. Firstly, the secondorder dynamic system was reformulated as the first-order system and the frame of reference was transfered by introducing new variables so that highly oscillatory behaviour inherits from the entries in the meantime. Then the modified Magnus integrator method based on local linearization was appropriately designed for solving the above new form and some improved also were presented. Finally, numerical examples show that the proposed methods appear to be quite adequate for integration for highly oscillatory dynamic systems including Hamiltonian systems problem with long time and effectiveness

  17. Novel Modified Elman Neural Network Control for PMSG System Based on Wind Turbine Emulator

    Directory of Open Access Journals (Sweden)

    Chih-Hong Lin

    2013-01-01

    Full Text Available The novel modified Elman neural network (NN controlled permanent magnet synchronous generator (PMSG system, which is directly driven by a permanent magnet synchronous motor (PMSM based on wind turbine emulator, is proposed to control output of rectifier (AC/DC power converter and inverter (DC/AC power converter in this study. First, a closed loop PMSM drive control based on wind turbine emulator is designed to generate power for the PMSG system according to different wind speeds. Then, the rotor speed of the PMSG, the voltage, and current of the power converter are detected simultaneously to yield better power output of the converter. Because the PMSG system is the nonlinear and time-varying system, two sets online trained modified Elman NN controllers are developed for the tracking controllers of DC bus power and AC power to improve output performance of rectifier and inverter. Finally, experimental results are verified to show the effectiveness of the proposed control scheme.

  18. Protein structure refinement using a quantum mechanics-based chemical shielding predictor

    DEFF Research Database (Denmark)

    Bratholm, Lars Andersen; Jensen, Jan Halborg

    2017-01-01

    The accurate prediction of protein chemical shifts using a quantum mechanics (QM)-based method has been the subject of intense research for more than 20 years but so far empirical methods for chemical shift prediction have proven more accurate. In this paper we show that a QM-based predictor...... of a protein backbone and CB chemical shifts (ProCS15, PeerJ, 2016, 3, e1344) is of comparable accuracy to empirical chemical shift predictors after chemical shift-based structural refinement that removes small structural errors. We present a method by which quantum chemistry based predictions of isotropic...

  19. Conventional SLA and chemically modified SLA implants in patients with poorly controlled type 2 diabetes mellitus--a randomized controlled trial.

    Science.gov (United States)

    Khandelwal, Namita; Oates, Thomas W; Vargas, Adriana; Alexander, Peggy P; Schoolfield, John D; Alex McMahan, C

    2013-01-01

    The objective of this study was to evaluate the potential for a chemically modified Sand blasted, Large grit, Acid etched (SLA) surface, compared with a conventional SLA surface, to enhance implant healing and integration in poorly controlled diabetic patients, a group previously demonstrated to have compromises and delays in implant stabilization during the metabolically active healing period following implant placement. The study enrolled 24 patients with type 2 diabetes, baseline HbA1c levels between 7.5-11.4%, and a minimum of two posterior mandibular tooth sites at least 4 months following extraction and appropriate for implant placement. Each patient, at a randomly selected site, received an implant with the conventional SLA surface; at the second site, the patient received an implant with the chemically modified SLA (modSLA) surface. Thus, 48 study implants were placed. Implant stability was assessed using Resonance Frequency Analysis (RFA). Readings were taken from the buccal and proximal directions for each implant. Implant stability (ISQ) was assessed at the time of surgical placement (baseline) and 2, 3, 4, 6, 8, 10, 12, and 16 weeks following implant placement. No significant differences in implant stability were observed between conventional SLA implants and modSLA implants, and the time courses of implant stabilization following implant placement were similar for the two implant types. Baseline ISQ and minimum ISQ was slightly higher in subjects with higher HbA1c levels, but were similar during 12-16 weeks following implant placement. Forty-seven (98%) of the 48 implants were determined to be successfully osseointegrated and continued to restoration. Implant stabilization was similar for the conventional SLA and chemically modified SLA implants in type 2 diabetic patients with relatively poor glycemic control. Furthermore, this study demonstrated clinically successful implant placement even in poorly controlled diabetic patients. © 2011 John Wiley

  20. Turbulence Effects on Modified State Observer-Based Adaptive Control: Black Kite Micro Aerial Vehicle

    Directory of Open Access Journals (Sweden)

    Venkatasubramani S. R. Pappu

    2016-02-01

    Full Text Available This paper presents the implementation of a modified state observer-based adaptive dynamic inverse controller for the Black Kite micro aerial vehicle. The pitch and velocity adaptations are computed by the modified state observer in the presence of turbulence to simulate atmospheric conditions. This state observer uses the estimation error to generate the adaptations and, hence, is more robust than model reference adaptive controllers which use modeling or tracking error. In prior work, a traditional proportional-integral-derivative control law was tested in simulation for its adaptive capability in the longitudinal dynamics of the Black Kite micro aerial vehicle. This controller tracks the altitude and velocity commands during normal conditions, but fails in the presence of both parameter uncertainties and system failures. The modified state observer-based adaptations, along with the proportional-integral-derivative controller enables tracking despite these conditions. To simulate flight of the micro aerial vehicle with turbulence, a Dryden turbulence model is included. The turbulence levels used are based on the absolute load factor experienced by the aircraft. The length scale was set to 2.0 meters with a turbulence intensity of 5.0 m/s that generates a moderate turbulence. Simulation results for various flight conditions show that the modified state observer-based adaptations were able to adapt to the uncertainties and the controller tracks the commanded altitude and velocity. The summary of results for all of the simulated test cases and the response plots of various states for typical flight cases are presented.

  1. Application study of piecewise context-based adaptive binary arithmetic coding combined with modified LZC

    Science.gov (United States)

    Su, Yan; Jun, Xie Cheng

    2006-08-01

    An algorithm of combining LZC and arithmetic coding algorithm for image compression is presented and both theory deduction and simulation result prove the correctness and feasibility of the algorithm. According to the characteristic of context-based adaptive binary arithmetic coding and entropy, LZC was modified to cooperate the optimized piecewise arithmetic coding, this algorithm improved the compression ratio without any additional time consumption compared to traditional method.

  2. Markov chain-based analysis of a modified Cooper-Frieze model

    Institute of Scientific and Technical Information of China (English)

    Jin-ying TONG; Zhen-ting HOU; Ding-hua SHI

    2009-01-01

    From the perspective of probability,the stability of a modified Cooper Frieze model is studied in the present paper.Based on the concept and technique of the first-passage probability in the Markov theory,we provide a rigorous proof for the existence of the steady-state degree distribution,and derive the explicit formula analytically.Moreover,we perform extensive numerical simulations of the model,including the degree distribution and the clustering.

  3. Gene Therapy Vectors with Enhanced Transfection Based on Hydrogels Modified with Affinity Peptides

    Science.gov (United States)

    Shepard, Jaclyn A.; Wesson, Paul J.; Wang, Christine E.; Stevans, Alyson C.; Holland, Samantha J.; Shikanov, Ariella; Grzybowski, Bartosz A.; Shea, Lonnie D.

    2011-01-01

    Regenerative strategies for damaged tissue aim to present biochemical cues that recruit and direct progenitor cell migration and differentiation. Hydrogels capable of localized gene delivery are being developed to provide a support for tissue growth, and as a versatile method to induce the expression of inductive proteins; however, the duration, level, and localization of expression isoften insufficient for regeneration. We thus investigated the modification of hydrogels with affinity peptides to enhance vector retention and increase transfection within the matrix. PEG hydrogels were modified with lysine-based repeats (K4, K8), which retained approximately 25% more vector than control peptides. Transfection increased 5- to 15-fold with K8 and K4 respectively, over the RDG control peptide. K8- and K4-modified hydrogels bound similar quantities of vector, yet the vector dissociation rate was reduced for K8, suggesting excessive binding that limited transfection. These hydrogels were subsequently applied to an in vitro co-culture model to induce NGF expression and promote neurite outgrowth. K4-modified hydrogels promoted maximal neurite outgrowth, likely due to retention of both the vector and the NGF. Thus, hydrogels modified with affinity peptides enhanced vector retention and increased gene delivery, and these hydrogels may provide a versatile scaffold for numerous regenerative medicine applications. PMID:21514659

  4. Modified TiO2 based photocatalysts for improved air and health quality

    Directory of Open Access Journals (Sweden)

    Vassilios Binas

    2017-03-01

    Full Text Available Photocatalysis with modified titania is a promising approach to improve both air and health quality. Modified titania with novel photocatalytic properties under indoor light irradiation leads to smart coatings, which are benchmark materials suitable for their indoor applications. It is generally accepted that the photocatalytic activity is affected by the light absorption, charge creation/recombination rate and surface reactivity. In this contribution we focus on modified TiO2 as catalyst in heterogeneous photo-catalytic processes and address the efficiency of TiO2-based building and construction materials on the removal of environmental pollutants indoors and outdoors. We also present data on the presence of eventually formed, toxicologically relevant and harmful by-products as the result of the photo-induced degradation of pollutants in an effort for better evaluation of induced risks for human health from the application of TiO2 modified materials. Finally, we present recent results on the disinfection performance of these material and the inactivation of severe pathogens contained in water and indoor air environments.

  5. Multifunctional Electrochemical Platforms Based on the Michael Addition/Schiff Base Reaction of Polydopamine Modified Reduced Graphene Oxide: Construction and Application.

    Science.gov (United States)

    Huang, Na; Zhang, Si; Yang, Liuqing; Liu, Meiling; Li, Haitao; Zhang, Youyu; Yao, Shouzhuo

    2015-08-19

    In this paper, a new strategy for the construction of multifunctional electrochemical detection platforms based on the Michael addition/Schiff base reaction of polydopamine modified reduced graphene oxide was first proposed. Inspired by the mussel adhesion proteins, 3,4-dihydroxyphenylalanine (DA) was selected as a reducing agent to simultaneously reduce graphene oxide and self-polymerize to obtain the polydopamine-reduced graphene oxide (PDA-rGO). The PDA-rGO was then functionalized with thiols and amines by the reaction of thiol/amino groups with quinine groups of PDA-rGO via the Michael addition/Schiff base reaction. Several typical compounds containing thiol and/or amino groups such as 1-[(4-amino)phenylethynyl] ferrocene (Fc-NH2), cysteine (cys), and glucose oxidase (GOx) were selected as the model molecules to anchor on the surface of PDA-rGO using the strategy for construction of multifunctional electrochemical platforms. The experiments revealed that the composite grafted with ferrocene derivative shows excellent catalysis activity toward many electroactive molecules and could be used for individual or simultaneous detection of dopamine hydrochloride (DA) and uric acid (UA), or hydroquinone (HQ) and catechol (CC), while, after grafting of cysteine on PDA-rGO, simultaneous discrimination detection of Pb(2+) and Cd(2+) was realized on the composite modified electrode. In addition, direct electron transfer of GOx can be observed when GOx-PDA-rGO was immobilized on glassy carbon electrode (GCE). When glucose was added into the system, the modified electrode showed excellent electric current response toward glucose. These results inferred that the proposed multifunctional electrochemical platforms could be simply, conveniently, and effectively regulated through changing the anchored recognition or reaction groups. This study would provide a versatile method to design more detection or biosensing platforms through a chemical reaction strategy in the future.

  6. Direct synthesis of hydrophobic graphene-based nanosheets via chemical modification of exfoliated graphene oxide.

    Science.gov (United States)

    Wang, Jigang; Wang, Yongsheng; He, Dawei; Liu, Zhiyong; Wu, Hongpeng; Wang, Haiteng; Zhao, Yu; Zhang, Hui; Yang, Bingyang; Xu, Haiteng; Fu, Ming

    2012-08-01

    Hydrophobic graphene-based material at the nanoscale was prepared by treatment of exfoliated graphene oxide with organic isocyanates. The lipophilic modified graphene oxide (LMGO) can then be exfoliated into the functionalized graphene nanoplatelets that can form a stable dispersion in polar aprotic solvents. AFM image shows the thickness of LMGO is approximately 1 nm. Characterization of LMGO by elemental analysis suggested that the chemical treatment results in the functionalization of the carboxyl and hydroxyl groups in GO via formation of amides and carbamate esters, respectively. The degree of GO functionalization can be controlled via either the reactivity of the isocyanate or the reaction time. Then we investigated the thermal properties of the SPFGraphene by using thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC), the TGA curve shows a greater weight loss of approximately 20% occurred indicating removal of functional groups from the LMGO sheets and an obvious exothermic peak at 176 degrees can be observed from 150 to 250 degrees. We also compared the structure of graphene oxide with the structure of chemical treated graphene oxide by FT-IR spectroscopy. The morphology and microstructure of the LMGO nanosheets were also characterized by SEM and XRD. Graphene can be used to fabricate a wide range of simple electronic devices such as field-effect transistors, resonators, quantum dots and some other extensive industrial manufacture such as super capacitor, li ion battery, solar cells and even transparent electrodes in device applications.

  7. Chemical Modification of Cyclodextrin and Amylose by Click Reaction and Its Application to the Synthesis of Poly-alkylamine-Modified Antibacterial Sugars.

    Science.gov (United States)

    Yamamura, Hatsuo

    2017-01-01

    Cyclodextrin (CD) can be chemically modified into desired and sophisticated functional molecules. However, poly-modification often produces complicated mixtures, resulting in a low yield of the desired product. As the most promising procedure to solve such problems and to achieve poly-modification of the CD molecule, we present here the Huisgen 1,3-dipolar cycloaddition, known as a click reaction. This review will describe the results of our microwave-assisted click reaction for the poly-modification of CD and amylose molecules, and its application to the study of synthetic membrane active antibacterial derivatives.

  8. Stable gene targeting in human cells using single-strand oligonucleotides with modified bases.

    Directory of Open Access Journals (Sweden)

    Xavier Rios

    Full Text Available Recent advances allow multiplexed genome engineering in E. coli, employing easily designed oligonucleotides to edit multiple loci simultaneously. A similar technology in human cells would greatly expedite functional genomics, both by enhancing our ability to test how individual variants such as single nucleotide polymorphisms (SNPs are related to specific phenotypes, and potentially allowing simultaneous mutation of multiple loci. However, oligo-mediated targeting of human cells is currently limited by low targeting efficiencies and low survival of modified cells. Using a HeLa-based EGFP-rescue reporter system we show that use of modified base analogs can increase targeting efficiency, in part by avoiding the mismatch repair machinery. We investigate the effects of oligonucleotide toxicity and find a strong correlation between the number of phosphorothioate bonds and toxicity. Stably EGFP-corrected cells were generated at a frequency of ~0.05% with an optimized oligonucleotide design combining modified bases and reduced number of phosphorothioate bonds. We provide evidence from comparative RNA-seq analysis suggesting cellular immunity induced by the oligonucleotides might contribute to the low viability of oligo-corrected cells. Further optimization of this method should allow rapid and scalable genome engineering in human cells.

  9. 2D-3D Face Recognition Method Based on a Modified CCA-PCA Algorithm

    Directory of Open Access Journals (Sweden)

    Patrik Kamencay

    2014-03-01

    Full Text Available This paper presents a proposed methodology for face recognition based on an information theory approach to coding and decoding face images. In this paper, we propose a 2D-3D face-matching method based on a principal component analysis (PCA algorithm using canonical correlation analysis (CCA to learn the mapping between a 2D face image and 3D face data. This method makes it possible to match a 2D face image with enrolled 3D face data. Our proposed fusion algorithm is based on the PCA method, which is applied to extract base features. PCA feature-level fusion requires the extraction of different features from the source data before features are merged together. Experimental results on the TEXAS face image database have shown that the classification and recognition results based on the modified CCA-PCA method are superior to those based on the CCA method. Testing the 2D-3D face match results gave a recognition rate for the CCA method of a quite poor 55% while the modified CCA method based on PCA-level fusion achieved a very good recognition score of 85%.

  10. Graphene Electronic Device Based Biosensors and Chemical Sensors

    Science.gov (United States)

    Jiang, Shan

    Two-dimensional layered materials, such as graphene and MoS2, are emerging as an exciting material system for a new generation of atomically thin electronic devices. With their ultrahigh surface to volume ratio and excellent electrical properties, 2D-layered materials hold the promise for the construction of a generation of chemical and biological sensors with unprecedented sensitivity. In my PhD thesis, I mainly focus on graphene based electronic biosensors and chemical sensors. In the first part of my thesis, I demonstrated the fabrication of graphene nanomesh (GNM), which is a graphene thin film with a periodic array of holes punctuated in it. The periodic holes introduce long periphery active edges that provide a high density of functional groups (e.g. carboxylic groups) to allow for covalent grafting of specific receptor molecules for chemical and biosensor applications. After covalently functionalizing the GNM with glucose oxidase, I managed to make a novel electronic sensor which can detect glucose as well as pH change. In the following part of my thesis I demonstrate the fabrication of graphene-hemin conjugate for nitric oxide detection. The non-covalent functionalization through pi-pi stacking interaction allows reliable immobilization of hemin molecules on graphene without damaging the graphene lattice to ensure the highly sensitive and specific detection of nitric oxide. The graphene-hemin nitric oxide sensor is capable of real-time monitoring of nitric oxide concentrations, which is of central importance for probing the diverse roles of nitric oxide in neurotransmission, cardiovascular systems, and immune responses. Our studies demonstrate that the graphene-hemin sensors can respond rapidly to nitric oxide in physiological environments with sub-nanomolar sensitivity. Furthermore, in vitro studies show that the graphene-hemin sensors can be used for the detection of nitric oxide released from macrophage cells and endothelial cells, demonstrating their

  11. One-pot chemical synthesis of small ubiquitin-like modifier protein-peptide conjugates using bis(2-sulfanylethyl)amido peptide latent thioester surrogates.

    Science.gov (United States)

    Boll, Emmanuelle; Drobecq, Hervé; Ollivier, Nathalie; Blanpain, Annick; Raibaut, Laurent; Desmet, Rémi; Vicogne, Jérôme; Melnyk, Oleg

    2015-02-01

    Small ubiquitin-like modifier (SUMO) post-translational modification (PTM) of proteins has a crucial role in the regulation of important cellular processes. This protocol describes the chemical synthesis of functional SUMO-peptide conjugates. The two crucial stages of this protocol are the solid-phase synthesis of peptide segments derivatized by thioester or bis(2-sulfanylethyl)amido (SEA) latent thioester functionalities and the one-pot assembly of the SUMO-peptide conjugate by a sequential native chemical ligation (NCL)/SEA native peptide ligation reaction sequence. This protocol also enables the isolation of a SUMO SEA latent thioester, which can be attached to a target peptide or protein in a subsequent step. It is compatible with 9-fluorenylmethoxycarbonyl (Fmoc) chemistry, and it gives access to homogeneous, reversible and functional SUMO conjugates that are not easily produced using living systems. The synthesis of SUMO-peptide conjugates on a milligram scale takes 20 working days.

  12. Towards combined electrochemistry and surface-enhanced resonance Raman of heme proteins: Improvement of diffusion electrochemistry of cytochrome c at silver electrodes chemically modified with 4-mercaptopyridine.

    Science.gov (United States)

    Millo, Diego; Ranieri, Antonio; Koot, Wynanda; Gooijer, Cees; van der Zwan, Gert

    2006-08-01

    To date, a successful combination of surface-enhanced resonance Raman spectroscopy (SERRS) and electrochemistry to study heme proteins is inhibited by the problems raised by the prerequisite to use silver as electrode metal. This paper indicates an approach to overcome these problems. It describes a quick and reproducible procedure to prepare silver electrodes chemically modified with 4-mercaptopyridine suitable to perform diffusion electrochemistry of cytochrome c (cyt c). The method involves the employment of a mechanical and a chemical treatment and avoids the use of alumina slurries and any electrochemical pretreatment. Cyclic voltammetry (CV) was used to test the electrochemical response of cyt c, and the CV signals were found identical with those obtained on gold electrodes under the same experimental conditions. Compared to previous literature, a significant improvement of the CV signal of cyt c at silver electrodes was achieved. Preliminary results show that this treatment can be also successfully employed for the preparation of SERRS-active electrodes.

  13. A Modified Model for Flexibility Analysis in Chemical Engineering Processes%化工过程中柔性分析的改进模型

    Institute of Scientific and Technical Information of China (English)

    张蕾; 何小荣; 徐强

    2004-01-01

    This paper discussed an extended model for flexibility analysis of chemical process. Under uncertainty, probability density function is used to describe uncertain parameters instead of hyper-rectangle, and chanceconstrained programming is a feasible way to deal with the violation of constraints. Because the feasible region of control variables would change along with uncertain parameters, its smallest acceptable size threshold is presented to ensure the controllability condition. By synthesizing the considerations mentioned above, a modified model can describe the flexibility analysis problem more exactly. Then a hybrid algorithm, which integrates stochastic simulation and genetic algorithm, is applied to solve this model and maximize the flexibility region. Both numerical and chemical process examples are presented to demonstrate the effectiveness of the method.

  14. Electrochemical impedance-based DNA sensor using a modified single walled carbon nanotube electrode

    Energy Technology Data Exchange (ETDEWEB)

    Weber, Jessica E. [Department of Mechanical Engineering, University of South Florida, Tampa, FL (United States); Nanomaterials and Nanomanufacturing Research Center, University of South Florida, Tampa, FL (United States); Pillai, Shreekumar [Center for NanoBiotechnology Research, Alabama State University, Montgomery, AL (United States); Ram, Manoj Kumar, E-mail: mkram@usf.edu [Department of Mechanical Engineering, University of South Florida, Tampa, FL (United States); Nanomaterials and Nanomanufacturing Research Center, University of South Florida, Tampa, FL (United States); Kumar, Ashok [Department of Mechanical Engineering, University of South Florida, Tampa, FL (United States); Nanomaterials and Nanomanufacturing Research Center, University of South Florida, Tampa, FL (United States); Singh, Shree R. [Center for NanoBiotechnology Research, Alabama State University, Montgomery, AL (United States)

    2011-07-20

    Carbon nanotubes have become promising functional materials for the development of advanced electrochemical biosensors with novel features which could promote electron-transfer with various redox active biomolecules. This paper presents the detection of Salmonella enterica serovar Typhimurium using chemically modified single walled carbon nanotubes (SWNTs) with single stranded DNA (ssDNA) on a polished glassy carbon electrode. Hybridization with the corresponding complementary ssDNA has shown a shift in the impedance studies due to a higher charge transfer in ssDNA. The developed biosensor has revealed an excellent specificity for the appropriate targeted DNA strand. The methodologies to prepare and functionalize the electrode could be adopted in the development of DNA hybridization biosensor.

  15. Advance in researches on chemically modified starch used in food%变性淀粉在食品中的应用研究进展

    Institute of Scientific and Technical Information of China (English)

    张静静; 梁艳; 宫丽华; 崔波

    2014-01-01

    Starch has become a kind of important industrial raw material as renewable natural resources . Because many inherent qualities of the original starch( infusibility in cold water,instability of paste liquid in acid,heat and shearing action)limit its industrial application.So people developed modified technology according to the starch structure and physical and chemical properties ,named modified starch .With many good properties of the modified starch ,its application in food industry is becoming more and more widely at home and abroad.This paper introduces preparation methods of modified starch,domain,and prospects the development of modified starch.%淀粉作为一种可再生的天然资源,已成为重要的工业原料。由于原淀粉的许多固有性质(冷水不溶性,糊液在酸、热、剪切作用下不稳定)限定了淀粉的工业应用,人们根据淀粉的结构和理化性质开发了淀粉的变性技术,即变性淀粉。随着变性淀粉诸多优良性质的显现,其在国内外食品行业的应用也越来越广泛。本文介绍了变性淀粉的制备方法及应用领域,并对变性淀粉的发展做了展望。

  16. Preparation and characterization of superhydrophobic surfaces based on hexamethyldisilazane-modified nanoporous alumina

    Directory of Open Access Journals (Sweden)

    Sanli Deniz

    2011-01-01

    Full Text Available Abstract Superhydrophobic nanoporous anodic aluminum oxide (alumina surfaces were prepared using treatment with vapor-phase hexamethyldisilazane (HMDS. Nanoporous alumina substrates were first made using a two-step anodization process. Subsequently, a repeated modification procedure was employed for efficient incorporation of the terminal methyl groups of HMDS to the alumina surface. Morphology of the surfaces was characterized by scanning electron microscopy, showing hexagonally ordered circular nanopores with approximately 250 nm in diameter and 300 nm of interpore distances. Fourier transform infrared spectroscopy-attenuated total reflectance analysis showed the presence of chemically bound methyl groups on the HMDS-modified nanoporous alumina surfaces. Wetting properties of these surfaces were characterized by measurements of the water contact angle which was found to reach 153.2 ± 2°. The contact angle values on HMDS-modified nanoporous alumina surfaces were found to be significantly larger than the average water contact angle of 82.9 ± 3° on smooth thin film alumina surfaces that underwent the same HMDS modification steps. The difference between the two cases was explained by the Cassie-Baxter theory of rough surface wetting.

  17. Effects of a Modified Through-Mask Drinking System (MDS) on Fluid Intake During Exercise in Chemical Protective Gear

    Science.gov (United States)

    1989-10-12

    in chemical protective gear. METHODS Test Subiects: Eighteen (18) unacclimated male volunteers were recruited from the military population at USARIEM...hydration status, a pretest urine sample was analyzed for specific gravity ( refractometry ) and no significant difference was observed between the two

  18. An Internet-Based Distributed Laboratory for Interactive Chemical Engineering Education

    Science.gov (United States)

    Guo, Jing; Kettler, David J.; Al-Dahhan, Muthanna

    2007-01-01

    A common undergraduate chemical engineering experiment has been modified for on-line operation over the Internet. By adopting rapidly changing Internet and object component technologies, we developed a novel approach combining the Internet and regular laboratory equipment. The client-server applications use a Visual Basic and Labtech programming…

  19. Hybrid Semiloof elements for plates and shells based upon a modified Hu-Washizu principle

    Science.gov (United States)

    Pian, T. H. H.; Sumihara, K.

    1984-01-01

    Hybrid SemiLoof elements for plates and shells are developed based upon modified Hu-Washizu principle. In the new version of the assumed stress hybrid formulation the equilibrium equations are satisfied through the introduction of internal displacement parameters as Lagrange multipliers. The inversion of the resulting H-matrices is simplified particularly when the stresses are expressed in terms of natural coordinates. A 24-DOF triangular element and a 32-DOF quadrilateral element based on shallow shell theory are derived and evaluated.

  20. MODIFIED BOTTLENECK-BASED PROCEDURE FOR LARGE-SCALE FLOW-SHOP SCHEDULING PROBLEMS WITH BOTTLENECK

    Institute of Scientific and Technical Information of China (English)

    ZUO Yan; GU Hanyu; XI Yugeng

    2006-01-01

    A new bottleneck-based heuristic for large-scale flow-shop scheduling problems with a bottleneck is proposed, which is simpler but more tailored than the shifting bottleneck (SB)procedure. In this algorithm, a schedule for the bottleneck machine is first constructed optimally and then the non-bottleneck machines are scheduled around the bottleneck schedule by some effective dispatching rules. Computational results show that the modified bottleneck-based procedure can achieve a tradeoff between solution quality and computational time comparing with SB procedure for medium-size problems. Furthermore it can obtain a good solution in quite short time for large-scale scheduling problems.