WorldWideScience

Sample records for greater chemical stability

  1. Search for greater stability in nuclear regulation

    International Nuclear Information System (INIS)

    Asselstine, J.K.

    1985-01-01

    The need for greater stability in nuclear regulation is discussed. Two possible approaches for dealing with the problems of new and rapidly changing regulatory requirements are discussed. The first approach relies on the more traditional licensing reform initiatives that have been considered off and on for the past decade. The second approach considers a new regulator philosophy aimed at the root causes of the proliferation of new safety requirements that have been imposed in recent years. For the past few years, the concepts of deregulation and regulatory reform have been in fashion in Washington, and the commercial nuclear power program has not remained unaffected. Many look to these concepts to provide greater stability in the regulatory program. The NRC, the nuclear industry and the administration have all been avidly pursuing regulatory reform initiatives, which take the form of both legislative and administrative proposals. Many of these proposals look to the future, and, if adopted, would have little impact on currently operating nuclear power plants or plants now under construction

  2. Chemically stabilized soils.

    Science.gov (United States)

    2009-12-01

    The objective of this study was to conduct laboratory evaluations to quantify the effects of compaction and moisture conditions on the strength of chemically treated soils typical utilized in pavement construction in Mississippi.

  3. Chemical and thermal stability of insulin

    DEFF Research Database (Denmark)

    Huus, Kasper; Havelund, Svend; Olsen, Helle B

    2006-01-01

    To study the correlation between the thermal and chemical stability of insulin formulations with various insulin hexamer ligands.......To study the correlation between the thermal and chemical stability of insulin formulations with various insulin hexamer ligands....

  4. Chemical stabilization of graphite surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Bistrika, Alexander A.; Lerner, Michael M.

    2018-04-03

    Embodiments of a device, or a component of a device, including a stabilized graphite surface, methods of stabilizing graphite surfaces, and uses for the devices or components are disclosed. The device or component includes a surface comprising graphite, and a plurality of haloaryl ions and/or haloalkyl ions bound to at least a portion of the graphite. The ions may be perhaloaryl ions and/or perhaloalkyl ions. In certain embodiments, the ions are perfluorobenzenesulfonate anions. Embodiments of the device or component including stabilized graphite surfaces may maintain a steady-state oxidation or reduction surface current density after being exposed to continuous oxidation conditions for a period of at least 1-100 hours. The device or component is prepared by exposing a graphite-containing surface to an acidic aqueous solution of the ions under oxidizing conditions. The device or component can be exposed in situ to the solution.

  5. Improvement of Expansive Soils Using Chemical Stabilizers

    Science.gov (United States)

    Ikizler, S. B.; Senol, A.; Khosrowshahi, S. K.; Hatipoğlu, M.

    2014-12-01

    The aim of this study is to investigate the effect of two chemical stabilizers on the swelling potential of expansive soil. A high plasticity sodium bentonite was used as the expansive soil. The additive materials including fly ash (FA) and lime (L) were evaluated as potential stabilizers to decrease the swelling pressure of bentonite. Depending on the type of additive materials, they were blended with bentonite in different percentages to assess the optimum state and approch the maximum swell pressure reduction. According to the results of swell pressure test, both fly ash and lime reduce the swelling potential of bentonite but the maximum improvement occurs using bentonite-lime mixture while the swelling pressure reduction approaches to 49%. The results reveal a significant reduction of swelling potential of expansive soil using chemical stabilizers. Keywords: Expansive soil; swell pressure; chemical stabilization; fly ash; lime

  6. Optimizing the dosage of stabilizing chemical

    OpenAIRE

    Harjula, Tomi

    2013-01-01

    A chemical company provides chemical treatment at customer mill in paper industry. This thesis work was done to determine the optimum dosage of stabilizing chemical. The theoretical framework explains the basics of paper brightness and bleaching and how these topics are connected to each other. The knowledge gained is very valuable and can possibly be used in the future in other similar applications as well. This thesis work contains confidential back ground information. Key ...

  7. Mercury stabilization in chemically bonded phosphate ceramics

    International Nuclear Information System (INIS)

    Wagh, A. S.; Singh, D.; Jeong, S. Y.

    2000-01-01

    Mercury stabilization and solidification is a significant challenge for conventional stabilization technologies. This is because of the stringent regulatory limits on leaching of its stabilized products. In a conventional cement stabilization process, Hg is converted at high pH to its hydroxide, which is not a very insoluble compound; hence the preferred route for Hg sulfidation to convert it into insoluble cinnabar (HgS). Unfortunately, efficient formation of this compound is pH-dependent. At a high pH, one obtains a more soluble Hg sulfate, in a very low pH range, insufficient immobilization occurs because of the escape of hydrogen sulfide, while efficient formation of HgS occurs only in a moderately acidic region. Thus, the pH range of 4 to 8 is where stabilization with Chemically Bonded Phosphate Ceramics (CBPC) is carried out. This paper discusses the authors experience on bench-scale stabilization of various US Department of Energy (DOE) waste streams containing Hg in the CBPC process. This process was developed to treat DOE's mixed waste streams. It is a room-temperature-setting process based on an acid-base reaction between magnesium oxide and monopotassium phosphate solution that forms a dense ceramic within hours. For Hg stabilization, addition of a small amount ( 2 S or K 2 S is sufficient in the binder composition. Here the Toxicity Characteristic Leaching Procedure (TCLP) results on CBPC waste forms of surrogate waste streams representing secondary Hg containing wastes such as combustion residues and Delphi DETOXtrademark residues are presented. The results show that although the current limit on leaching of Hg is 0.2 mg/L, the results from the CBPC waste forms are at least one order lower than this stringent limit. Encouraged by these results on surrogate wastes, they treated actual low-level Hg-containing mixed waste from their facility at Idaho. TCLP results on this waste are presented here. The efficient stabilization in all these cases is

  8. Perovskite solar cells with CuSCN hole extraction layers yield stabilized efficiencies greater than 20%

    Science.gov (United States)

    Arora, Neha; Dar, M. Ibrahim; Hinderhofer, Alexander; Pellet, Norman; Schreiber, Frank; Zakeeruddin, Shaik Mohammed; Grätzel, Michael

    2017-11-01

    Perovskite solar cells (PSCs) with efficiencies greater than 20% have been realized only with expensive organic hole-transporting materials. We demonstrate PSCs that achieve stabilized efficiencies exceeding 20% with copper(I) thiocyanate (CuSCN) as the hole extraction layer. A fast solvent removal method enabled the creation of compact, highly conformal CuSCN layers that facilitate rapid carrier extraction and collection. The PSCs showed high thermal stability under long-term heating, although their operational stability was poor. This instability originated from potential-induced degradation of the CuSCN/Au contact. The addition of a conductive reduced graphene oxide spacer layer between CuSCN and gold allowed PSCs to retain >95% of their initial efficiency after aging at a maximum power point for 1000 hours under full solar intensity at 60°C. Under both continuous full-sun illumination and thermal stress, CuSCN-based devices surpassed the stability of spiro-OMeTAD-based PSCs.

  9. The Quest for Greater Chemical Energy Storage: A Deceiving Game of Nanometer Manipulation

    Science.gov (United States)

    Lindsay, C. Michael

    2015-06-01

    It is well known that modern energetic materials based on organic chemistry have nearly reached a plateau in performance with only ~ 40% improvement realized over the past half century. This fact has stimulated research on alternative chemical energy storage schema in various US government funded ``High Energy Density Materials'' (HEDM) programs since the 1950's. These efforts have examined a wide range of phenomena such as free radical stabilization, metallic hydrogen, metastable helium, polynitrogens, extended molecular solids, nanothermites, and others. In spite of the substantial research investments, significant improvements in energetic material performance have not been forthcoming. In this talk we will survey various fundamental modes of chemical energy storage, lesson's learned in the various HEDM programs, and areas that are being explored currently. A recurring theme in all of this work is the challenge to successfully manipulate and stabilize matter at the ~ 1 nm scale.

  10. Chemical stability of levoglucosan: An isotopic perspective

    Science.gov (United States)

    Sang, X. F.; Gensch, I.; Kammer, B.; Khan, A.; Kleist, E.; Laumer, W.; Schlag, P.; Schmitt, S. H.; Wildt, J.; Zhao, R.; Mungall, E. L.; Abbatt, J. P. D.; Kiendler-Scharr, A.

    2016-05-01

    The chemical stability of levoglucosan was studied by exploring its isotopic fractionation during the oxidation by hydroxyl radicals. Aqueous solutions as well as mixed (NH4)2SO4-levoglucosan particles were exposed to OH. In both cases, samples experiencing different extents of processing were isotopically analyzed by Thermal Desorption-Gas Chromatography-Isotope Ratio Mass Spectrometry (TD-GC-IRMS). From the dependence of levoglucosan δ13C and concentration on the reaction extent, the kinetic isotope effect (KIE) of the OH oxidation reactions was determined to be 1.00187±0.00027 and 1.00229±0.00018, respectively. Both show good agreement within the uncertainty range. For the heterogeneous oxidation of particulate levoglucosan by gas-phase OH, a reaction rate constant of (2.67±0.03)·10-12 cm3 molecule-1S-1 was derived. The laboratory kinetic data, together with isotopic source and ambient observations, give information on the extent of aerosol chemical processing in the atmosphere.

  11. Chemical stability of high-temperature superconductors

    Science.gov (United States)

    Bansal, Narottam P.

    1992-01-01

    A review of the available studies on the chemical stability of the high temperature superconductors (HTS) in various environments was made. The La(1.8)Ba(0.2)CuO4 HTS is unstable in the presence of H2O, CO2, and CO. The YBa2Cu3O(7-x) superconductor is highly susceptible to degradation in different environments, especially water. The La(2-x)Ba(x)CuO4 and Bi-Sr-Ca-Cu-O HTS are relatively less reactive than the YBa2Cu3O(7-x). Processing of YBa2Cu3O(7-x) HTS in purified oxygen, rather than in air, using high purity noncarbon containing starting materials is recommended. Exposure of this HTS to the ambient atmosphere should also be avoided at all stages during processing and storage. Devices and components made out of these oxide superconductors would have to be protected with an impermeable coating of a polymer, glass, or metal to avoid deterioration during use.

  12. Stability of a chemically active floating disk

    Science.gov (United States)

    Vandadi, Vahid; Jafari Kang, Saeed; Rothstein, Jonathan; Masoud, Hassan

    2017-11-01

    We theoretically study the translational stability of a chemically active disk located at a flat liquid-gas interface. The initially immobile circular disk uniformly releases an interface-active agent that locally changes the surface tension and is insoluble in the bulk. If left unperturbed, the stationary disk remains motionless as the agent is discharged. Neglecting the inertial effects, we numerically test whether a perturbation in the translational velocity of the disk can lead to its spontaneous and self-sustained motion. Such a perturbation gives rise to an asymmetric distribution of the released factor that could trigger and sustain the Marangoni propulsion of the disk. An implicit Fourier-Chebyshev spectral method is employed to solve the advection-diffusion equation for the concentration of the active agent. The solution, given a linear equation of state for the surface tension, provides the shear stress distribution at the interface. This and the no-slip condition on the wetted surface of the disk are then used at each time step to semi-analytically determine the Stokes flow in the semi-infinite liquid layer. Overall, the findings of our investigation pave the way for pinpointing the conditions under which interface-bound active particles become dynamically unstable.

  13. Chemical Stability of Telavancin in Elastomeric Pumps☆

    Science.gov (United States)

    Sand, Patrick; Aladeen, Traci; Kirkegaard, Paul; LaChance, Dennis; Slover, Christine

    2015-01-01

    Background VIBATIV is a once-daily, injectable lipoglycopeptide antibiotic approved in the U.S. for the treatment of hospital-acquired and ventilator-associated bacterial pneumonia (HABP/VABP) caused by susceptible isolates of Staphylococcus aureus when alternative treatments are not suitable. In addition, VIBATIV is approved in the U.S. for the treatment of adult patients with complicated skin & skin structure infections (cSSSI) caused by susceptible isolates of Gram-positive bacteria, including Staphylococcus aureus, both methicillin-susceptible (MSSA) and methicillin-resistant (MRSA) strains. Objective To evaluate the chemical stability of telavancin (Vibativ; Theravance Biopharma US, Inc, Northbrook, Illinois), a lipoglycopeptide antibiotic with activity against methicillin-resistant Staphylococcus aureus, in 2 types of elastomeric pumps, the Intermate Infusion System (Baxter International Inc) and the Homepump Eclipse (I-Flow Corporation). Methods Different sizes of the Baxter (Ontario, Canada) (105 mL and 275 mL) and I-Flow (Stoughton, Massachusetts) (100 mL and 250 mL) pumps were compared with glass controls. The telavancin drug product was reconstituted and diluted to concentrations of 0.6 mg/mL and 8.0 mg/mL using either 0.9% saline, 5% dextrose in water, or sterilized water for injection (0.6 mg/mL telavancin) or saline (8.0 mg/mL telavancin) followed by Ringer’s Lactate solution. Pumps were filled and stored at 2°C to 8°C, protected from light. Aliquots from both pump types and for all telavancin reconstitution/dilution schemes and concentrations were taken over a period of 8 days and analyzed for appearance, pH, telavancin concentration and purity, and degradation products. Results The pH of all pump solutions remained consistent throughout the 8-day analysis period, within a range of 4.6 to 5.7 for the 0.6 mg/mL and 4.4 to 4.9 for the 8.0 mg/mL telavancin solutions. There was no significant change in the chromatographic purity for any of the pump

  14. Chemical Stability of Telavancin in Elastomeric Pumps.

    Science.gov (United States)

    Sand, Patrick; Aladeen, Traci; Kirkegaard, Paul; LaChance, Dennis; Slover, Christine

    2015-12-01

    VIBATIV is a once-daily, injectable lipoglycopeptide antibiotic approved in the U.S. for the treatment of hospital-acquired and ventilator-associated bacterial pneumonia (HABP/VABP) caused by susceptible isolates of Staphylococcus aureus when alternative treatments are not suitable. In addition, VIBATIV is approved in the U.S. for the treatment of adult patients with complicated skin & skin structure infections (cSSSI) caused by susceptible isolates of Gram-positive bacteria, including Staphylococcus aureus, both methicillin-susceptible (MSSA) and methicillin-resistant (MRSA) strains. To evaluate the chemical stability of telavancin (Vibativ; Theravance Biopharma US, Inc, Northbrook, Illinois), a lipoglycopeptide antibiotic with activity against methicillin-resistant Staphylococcus aureus, in 2 types of elastomeric pumps, the Intermate Infusion System (Baxter International Inc) and the Homepump Eclipse (I-Flow Corporation). Different sizes of the Baxter (Ontario, Canada) (105 mL and 275 mL) and I-Flow (Stoughton, Massachusetts) (100 mL and 250 mL) pumps were compared with glass controls. The telavancin drug product was reconstituted and diluted to concentrations of 0.6 mg/mL and 8.0 mg/mL using either 0.9% saline, 5% dextrose in water, or sterilized water for injection (0.6 mg/mL telavancin) or saline (8.0 mg/mL telavancin) followed by Ringer's Lactate solution. Pumps were filled and stored at 2°C to 8°C, protected from light. Aliquots from both pump types and for all telavancin reconstitution/dilution schemes and concentrations were taken over a period of 8 days and analyzed for appearance, pH, telavancin concentration and purity, and degradation products. The pH of all pump solutions remained consistent throughout the 8-day analysis period, within a range of 4.6 to 5.7 for the 0.6 mg/mL and 4.4 to 4.9 for the 8.0 mg/mL telavancin solutions. There was no significant change in the chromatographic purity for any of the pump solutions examined. All decreases in

  15. Effect of Chemical Stabilizers in Silver Nanoparticle Suspensions on Nanotoxicity

    International Nuclear Information System (INIS)

    Bae, Eun Joo; Park, Hee Jin; Park, Jun Su; Yoon, Je Yong; Yi, Jong Heop; Kim, Young Hun; Choi, Kyung Hee

    2011-01-01

    Colloidal silver nanoparticles (AgNPs) have been commercialized as the typically stabilized form via the addition of a variety of surfactants or polymers. Herein, to examine the effects of stabilizing AgNPs in suspension, we modified the surface of bare AgNPs with four type of surfactants (NaDDBS, SDS, TW80, CTAB) and polymers (PVP, PAA, PAH, CMC). The modified AgNPs was applied to compare suspension stability and nanotoxicity test using Escherichia coli (E. coli) as a model organism. Modification of AgNPs surface using chemical stabilizer may be not related with molecular weight, but chemical structure such as ionic state and functional group of stabilizer. In this study, it is noteworthy that AgNPs modified with a cationic stabilizer (CTAB, PAH) were importantly toxic to E. coli, rather than anionic stabilizers (NaDDBS, SDS). Comparing similar anionic stabilizer, i.e., NaDDBS and SDS, the result showed that lipophilicity of chemical structure can affect on E. coli, because NaDDBS, which contains a lipophilic benzene ring, accelerated the cytotoxicity of AgNPs. Interestingly, none of the stabilizers tested, including biocompatible nonionic stabilizers (i.e., TW80 and cellulose) caused a reduction in AgNP toxicity. This showed that toxicity of AgNPs cannot be reduced using stabilizers

  16. Effect of Chemical Stabilizers in Silver Nanoparticle Suspensions on Nanotoxicity

    Energy Technology Data Exchange (ETDEWEB)

    Bae, Eun Joo; Park, Hee Jin; Park, Jun Su; Yoon, Je Yong; Yi, Jong Heop [Seoul National University, Seoul (Korea, Republic of); Kim, Young Hun [Kwangwoon University, Seoul (Korea, Republic of); Choi, Kyung Hee [National Institute of Environmental Research, Incheon (Korea, Republic of)

    2011-02-15

    Colloidal silver nanoparticles (AgNPs) have been commercialized as the typically stabilized form via the addition of a variety of surfactants or polymers. Herein, to examine the effects of stabilizing AgNPs in suspension, we modified the surface of bare AgNPs with four type of surfactants (NaDDBS, SDS, TW80, CTAB) and polymers (PVP, PAA, PAH, CMC). The modified AgNPs was applied to compare suspension stability and nanotoxicity test using Escherichia coli (E. coli) as a model organism. Modification of AgNPs surface using chemical stabilizer may be not related with molecular weight, but chemical structure such as ionic state and functional group of stabilizer. In this study, it is noteworthy that AgNPs modified with a cationic stabilizer (CTAB, PAH) were importantly toxic to E. coli, rather than anionic stabilizers (NaDDBS, SDS). Comparing similar anionic stabilizer, i.e., NaDDBS and SDS, the result showed that lipophilicity of chemical structure can affect on E. coli, because NaDDBS, which contains a lipophilic benzene ring, accelerated the cytotoxicity of AgNPs. Interestingly, none of the stabilizers tested, including biocompatible nonionic stabilizers (i.e., TW80 and cellulose) caused a reduction in AgNP toxicity. This showed that toxicity of AgNPs cannot be reduced using stabilizers.

  17. Measurements of radiological background and some chemical pollutants in two areas of greater cairo

    International Nuclear Information System (INIS)

    Tawfik, F.S.; Ramadan, A.; Abdel Aziz, M.A.; Aly, A.I.M.

    2002-01-01

    The present work aims to the evaluation of radiological background levels and chemical pollutants in greater cairo as the most dense populated city in Egypt. The meteorological data of a complete one year of Cairo city have been collected, investigated and processed to determined the behavior of the pollutants in the atmosphere and the sector that is strongly affected by the pollutants. Portable detector for measuring the radiological background was deployed in Nasr City, where two nuclear centers belonging to Atomic Energy Authority are located, to measure the radioactivity levels in the atmosphere and compare them with the international standard limits. Other detectors were deployed in Shobra El- Khema area to study two significant phenomena, the first is the formation of ozone through the photo-chemical oxidation, its level and its behavior in the atmosphere, taking into consideration the international standard limits. The second phenomenon is the impact of the black plume on the capital Cairo started on October (1999) and its association of pollutant levels increment, defining the nature and the site location of the pollutant source. The carbon monoxide concentrations (as an example), before and during the black plume, were calculated using Gaussian equation then compared with the measured data in Shobra El- Khema region. The other available instruments were used to measure nitrogen oxides, ozone and carbon monoxide

  18. Chemical stability of oseltamivir in oral solutions.

    Science.gov (United States)

    Albert, K; Bockshorn, J

    2007-09-01

    The stability of oseltamivir in oral aqueous solutions containing the preservative sodium benzoate was studied by a stability indicating HPLC-method. The separation was achieved on a RP-18 ec column using a gradient of mobile phase A (aqueous solution of 50 mM ammonium acetate) and mobile phase B (60% (v/v) acetonitrile/40% (v/v) mobile phase A). The assay was subsequently validated according to the ICH guideline Q2(R1). The extemporaneously prepared "Oseltamivir Oral Solution 15 mg/ml for Adults or for Children" (NRF 31.2.) according to the German National Formulary ("Neues Rezeptur-Formularium") was stable for 84 days if stored under refrigeration. After storage at 25 degrees C the content of oseltamivir decreased to 98.4%. Considering the toxicological limit of 0.5% of the 5-acetylamino derivative (the so-called isomer I) the solution is stable for 46 days. Oseltamivir was less stable in a solution prepared with potable water instead of purified water. Due to an increasing pH the stability of this solution decreased to 14 days. Furthermore a white precipitate of mainly calcium phosphate was observed. The addition of 0.1% anhydrous citric acid avoided these problems and improved the stability of the solution prepared with potable water to 63 days. Sodium benzoate was stable in all oral solutions tested.

  19. The quest for greater chemical energy storage in energetic materials: Grounding expectations

    Science.gov (United States)

    Lindsay, C. Michael; Fajardo, Mario E.

    2017-01-01

    It is well known that the performance of modern energetic materials based on organic chemistry has plateaued, with only ˜ 40% improvements realized over the past half century. This fact has stimulated research on alternative chemical energy storage schemes in various U.S. government funded "High Energy Density Materials" (HEDM) programs since the 1950's. These efforts have examined a wide range of phenomena such as free radical stabilization, metallic hydrogen, metastable helium, polynitrogens, extended molecular solids, nanothermites, and others. In spite of the substantial research investments, significant improvements in energetic material performance have not been forthcoming. This paper discusses the lessons learned in the various HEDM programs, the different degrees of freedom in which to store energy in materials, and the fundamental limitations and orders of magnitude of the energies involved. The discussion focuses almost exclusively on the topic of energy density and only mentions in passing other equally important properties of explosives and propellants such as gas generation and reaction rate.

  20. Chemical Stability of Telavancin in Elastomeric Pumps

    Directory of Open Access Journals (Sweden)

    Patrick Sand, MSc

    2015-12-01

    Conclusions: The results of this study indicate that telavancin remains chemically stable when diluted in the Intermate Infusion System and the Homepump Eclipse elastomeric pumps and stored at 2°C to 8°C for up to 8 days protected from light at the concentration range and dilution schemes evaluated.

  1. On the Chemical Stabilities of Ionic Liquids

    Directory of Open Access Journals (Sweden)

    Yen-Ho Chu

    2009-09-01

    Full Text Available Ionic liquids are novel solvents of interest as greener alternatives to conventional organic solvents aimed at facilitating sustainable chemistry. As a consequence of their unusual physical properties, reusability, and eco-friendly nature, ionic liquids have attracted the attention of organic chemists. Numerous reports have revealed that many catalysts and reagents were supported in the ionic liquid phase, resulting in enhanced reactivity and selectivity in various important reaction transformations. However, synthetic chemists cannot ignore the stability data and intermolecular interactions, or even reactions that are directly applicable to organic reactions in ionic liquids. It is becoming evident from the increasing number of reports on use of ionic liquids as solvents, catalysts, and reagents in organic synthesis that they are not totally inert under many reaction conditions. While in some cases, their unexpected reactivity has proven fortuitous and in others, it is imperative that when selecting an ionic liquid for a particular synthetic application, attention must be paid to its compatibility with the reaction conditions. Even though, more than 200 room temperature ionic liquids are known, only a few reports have commented their effects on reaction mechanisms or rate/stability. Therefore, rather than attempting to give a comprehensive overview of ionic liquid chemistry, this review focuses on the non-innocent nature of ionic liquids, with a decided emphasis to clearly illuminate the ability of ionic liquids to affect the mechanistic aspects of some organic reactions thereby affecting and promoting the yield and selectivity.

  2. On the chemical stabilities of ionic liquids.

    Science.gov (United States)

    Sowmiah, Subbiah; Srinivasadesikan, Venkatesan; Tseng, Ming-Chung; Chu, Yen-Ho

    2009-09-25

    Ionic liquids are novel solvents of interest as greener alternatives to conventional organic solvents aimed at facilitating sustainable chemistry. As a consequence of their unusual physical properties, reusability, and eco-friendly nature, ionic liquids have attracted the attention of organic chemists. Numerous reports have revealed that many catalysts and reagents were supported in the ionic liquid phase, resulting in enhanced reactivity and selectivity in various important reaction transformations. However, synthetic chemists cannot ignore the stability data and intermolecular interactions, or even reactions that are directly applicable to organic reactions in ionic liquids. It is becoming evident from the increasing number of reports on use of ionic liquids as solvents, catalysts, and reagents in organic synthesis that they are not totally inert under many reaction conditions. While in some cases, their unexpected reactivity has proven fortuitously advantageous in others is has been a problem, it is imperative that when selecting an ionic liquid for a particular synthetic application, attention be paid to its compatibility with the reaction conditions. Even though, more than 200 room temperature ionic liquids are known, only a few reports have commented their effects on reaction mechanisms or rate/stability. Therefore, rather than attempting to give a comprehensive overview of ionic liquid chemistry, this review focuses on the non-innocent nature of ionic liquids, with a decided emphasis to clearly illuminate the ability of ionic liquids to affect the mechanistic aspects of some organic reactions thereby affecting and promoting the yield and selectivity.

  3. Accelerated decay rates drive soil organic matter persistence and storage in temperate forests via greater mineral stabilization of microbial residues.

    Science.gov (United States)

    Phillips, R.; Craig, M.; Turner, B. L.; Liang, C.

    2017-12-01

    Climate predicts soil organic matter (SOM) stocks at the global scale, yet controls on SOM stocks at finer spatial scales are still debated. A current hypothesis predicts that carbon (C) and nitrogen (N) storage in soils should be greater when decomposition is slow owing to microbial competition for nutrients or the recalcitrance of organic substrates (hereafter the `slow decay' hypothesis). An alternative hypothesis predicts that soil C and N storage should be greater in soils with rapid decomposition, owing to the accelerated production of microbial residues and their stabilization on soil minerals (hereafter the `stabilization hypothesis'). To test these alternative hypotheses, we quantified soil C and N to 1-m depth in temperate forests across the Eastern and Midwestern US that varied in their biotic, climatic, and edaphic properties. At each site, we sampled (1) soils dominated by arbuscular mycorrhizal (AM) tree species, which typically have fast decay rates and accelerated N cycling, (2) soils dominated by ectomycorrhizal (ECM) tree species, which generally have slow decay rates and slow N cycling, and (3) soils supporting both AM and ECM trees. To the extent that trees and theor associated microbes reflect and reinforce soil conditions, support for the slow decay hypothesis would be greater SOM storage in ECM soils, whereas support for the stabilization hypothesis would be greater SOM storage in AM soils. We found support for both hypotheses, as slow decomposition in ECM soils increased C and N storage in topsoil, whereas fast decomposition in AM soils increased C and N storage in subsoil. However, at all sites we found 57% greater total C and N storage in the entire profile in AM- soils (P stabilization hypothesis. Amino sugar biomarkers (an indicator of microbial necromass) and particle size fractionation revealed that the greater SOM storage in AM soils was driven by an accumulation of microbial residues on clay minerals and metal oxides. Taken together

  4. Steam Reforming of Acetic Acid over Co-Supported Catalysts: Coupling Ketonization for Greater Stability

    Energy Technology Data Exchange (ETDEWEB)

    Davidson, Stephen D. [Energy and Environmental; Spies, Kurt A. [Energy and Environmental; Mei, Donghai [Energy and Environmental; Kovarik, Libor [Energy and Environmental; Kutnyakov, Igor [Energy and Environmental; Li, Xiaohong S. [Energy and Environmental; Lebarbier Dagle, Vanessa [Energy and Environmental; Albrecht, Karl O. [Energy and Environmental; Dagle, Robert A. [Energy and Environmental

    2017-09-11

    We report on the markedly improved stability of a novel 2-bed catalytic system, as compared to a conventional 1-bed steam reforming catalyst, for the production of H2 from acetic acid. The 2-bed catalytic system comprises of i) a basic oxide ketonization catalyst for the conversion of acetic acid to acetone, and a ii) Co-based steam reforming catalyst, both catalytic beds placed in sequence within the same unit operation. Steam reforming catalysts are particularly prone to catalytic deactivation when steam reforming acetic acid, used here as a model compound for the aqueous fraction of bio-oil. Catalysts comprising MgAl2O4, ZnO, CeO2, and activated carbon (AC) both with and without Co-addition were evaluated for conversion of acetic acid and acetone, its ketonization product, in the presence of steam. It was found that over the bare oxide support only ketonization activity was observed and coke deposition was minimal. With addition of Co to the oxide support steam reforming activity was facilitated and coke deposition was significantly increased. Acetone steam reforming over the same Co-supported catalysts demonstrated more stable performance and with less coke deposition than with acetic acid feedstock. DFT analysis suggests that over Co surface CHxCOO species are more favorably formed from acetic acid versus acetone. These CHxCOO species are strongly bound to the Co catalyst surface and could explain the higher propensity for coke formation from acetic acid. Based on these findings, in order to enhance stability of the steam reforming catalyst a dual-bed (2-bed) catalyst system was implemented. Comparing the 2-bed and 1-bed (Co-supported catalyst only) systems under otherwise identical reaction conditions the 2-bed demonstrated significantly improved stability and coke deposition was decreased by a factor of 4.

  5. Chemical stabilization of porous silicon for enhanced biofunctionalization with immunoglobulin

    Directory of Open Access Journals (Sweden)

    Nelson Naveas, Vicente Torres Costa, Dario Gallach, Jacobo Hernandez-Montelongo, Raul Jose Martín Palma, Josefa Predenstinacion Garcia-Ruiz and Miguel Manso-Silván

    2012-01-01

    Full Text Available Porous silicon (PSi is widely used in biological experiments, owing to its biocompatibility and well-established fabrication methods that allow tailoring its surface. Nevertheless, there are some unresolved issues such as deciding whether the stabilization of PSi is necessary for its biological applications and evaluating the effects of PSi stabilization on the surface biofunctionalization with proteins. In this work we demonstrate that non-stabilized PSi is prone to detachment owing to the stress induced upon biomolecular adsorption. Biofunctionalized non-stabilized PSi loses the interference properties characteristic of a thin film, and groove-like structures resulting from a final layer collapse were observed by scanning electron microscopy. Likewise, direct PSi derivatization with 3-aminopropyl-triethoxysilane (APTS does not stabilize PSi against immunoglobulin biofunctionalization. To overcome this problem, we developed a simple chemical process of stabilizing PSi (CoxPSi for biological applications, which has several advantages over thermal stabilization (ToxPSi. The process consists of chemical oxidation in H2O2, surface derivatization with APTS and a curing step at 120 °C. This process offers integral homogeneous PSi morphology, hydrophilic surface termination (contact angle θ = 26° and highly efficient derivatized and biofunctionalized PSi surfaces (six times more efficient than ToxPSi. All these features are highly desirable for biological applications, such as biosensing, where our results can be used for the design and optimization of the biomolecular immobilization cascade on PSi surfaces.

  6. Stability of biogenic metal(loid) nanomaterials related to the colloidal stabilization theory of chemical nanostructures.

    Science.gov (United States)

    Piacenza, Elena; Presentato, Alessandro; Turner, Raymond J

    2018-02-25

    In the last 15 years, the exploitation of biological systems (i.e. plants, bacteria, mycelial fungi, yeasts, and algae) to produce metal(loid) (Me)-based nanomaterials has been evaluated as eco-friendly and a cost-effective alternative to the chemical synthesis processes. Although the biological mechanisms of biogenic Me-nanomaterial (Bio-Me-nanomaterials) production are not yet completely elucidated, a key advantage of such bio-nanostructures over those chemically synthesized is related to their natural thermodynamic stability, with several studies ascribed to the presence of an organic layer surrounding these Bio-Me-nanostructures. Different macromolecules (e.g. proteins, peptides, lipids, DNA, and polysaccharides) or secondary metabolites (e.g. flavonoids, terpenoids, glycosides, organic acids, and alkaloids) naturally produced by organisms have been indicated as main contributors to the stabilization of Bio-Me-nanostructures. Nevertheless, the chemical-physical mechanisms behind the ability of these molecules in providing stability to Bio-Me-nanomaterials are unknown. In this context, transposing the stabilization theory of chemically synthesized Me-nanomaterials (Ch-Me-nanomaterials) to biogenic materials can be used towards a better comprehension of macromolecules and secondary metabolites role as stabilizing agents of Bio-Me-nanomaterials. According to this theory, nanomaterials are generally featured by high thermodynamic instability in suspension, due to their high surface area and surface energy. This feature leads to the necessity to stabilize chemical nanostructures, even during or directly after their synthesis, through the development of (i) electrostatic, (ii) steric, or (iii) electrosteric interactions occurring between molecules and nanomaterials in suspension. Based on these three mechanisms, this review is focused on parallels between the stabilization of biogenic or chemical nanomaterials, suggesting which chemical-physical mechanisms may be

  7. Wintertime aerosol chemical composition, volatility, and spatial variability in the greater London area

    Directory of Open Access Journals (Sweden)

    L. Xu

    2016-02-01

    Full Text Available The composition of PM1 (particulate matter with diameter less than 1 µm in the greater London area was characterized during the Clean Air for London (ClearfLo project in winter 2012. Two high-resolution time-of-flight aerosol mass spectrometers (HR-ToF-AMS were deployed at a rural site (Detling, Kent and an urban site (North Kensington, London. The simultaneous and high-temporal resolution measurements at the two sites provide a unique opportunity to investigate the spatial distribution of PM1. We find that the organic aerosol (OA concentration is comparable between the rural and urban sites, but the contribution from different sources is distinctly different between the two sites. The concentration of solid fuel OA at the urban site is about twice as high as at the rural site, due to elevated domestic heating in the urban area. While the concentrations of oxygenated OA (OOA are well-correlated between the two sites, the OOA concentration at the rural site is almost twice that of the urban site. At the rural site, more than 70 % of the carbon in OOA is estimated to be non-fossil, which suggests that OOA is likely related to aged biomass burning considering the small amount of biogenic SOA in winter. Thus, it is possible that the biomass burning OA contributes a larger fraction of ambient OA in wintertime than what previous field studies have suggested. A suite of instruments was deployed downstream of a thermal denuder (TD to investigate the volatility of PM1 species at the rural Detling site. After heating at 250 °C in the TD, 40 % of the residual mass is OA, indicating the presence of non-volatile organics in the aerosol. Although the OA associated with refractory black carbon (rBC; measured by a soot-particle aerosol mass spectrometer only accounts for < 10 % of the total OA (measured by a HR-ToF-AMS at 250 °C, the two measurements are well-correlated, suggesting that the non-volatile organics have similar sources or have

  8. Physical and chemical stability of pemetrexed in infusion solutions.

    Science.gov (United States)

    Zhang, Yanping; Trissel, Lawrence A

    2006-06-01

    Pemetrexed is a multitargeted, antifolate, antineoplastic agent that is indicated for single-agent use in locally advanced or metastatic non-small-cell lung cancer after prior chemotherapy and in combination with cisplatin for the treatment of malignant pleural mesothelioma not treatable by surgery. Currently, there is no information on the long-term stability of pemetrexed beyond 24 hours. To evaluate the longer-term physical and chemical stability of pemetrexed 2, 10, and 20 mg/mL in polyvinyl chloride (PVC) bags of dextrose 5% injection and NaCl 0.9% injection. Triplicate samples of pemetrexed were prepared in the concentrations and infusion solutions required. Evaluations for physical and chemical stability were performed initially and over 2 days at 23 degrees C protected from light and exposed to fluorescent light, and over 31 days of storage at 4 degrees C protected from light. Physical stability was assessed using turbidimetric and particulate measurement as well as visual observation. Chemical stability was evaluated by HPLC. All pemetrexed solutions remained chemically stable, with little or no loss of pemetrexed over 2 days at 23 degrees C, protected from light and exposed to fluorescent light, and over 31 days of storage at 4 degrees C, protected from light. The room temperature samples were physically stable throughout the 48 hour test period. However, pemetrexed admixtures developed large numbers of microparticulates during refrigerated storage exceeding 24 hours. Pemetrexed is chemically stable for 2 days at room temperature and 31 days refrigerated in dextrose 5% injection and NaCl 0.9% injection. However, substantial numbers of microparticulates may form in pemetrexed diluted in the infusion solutions in PVC bags, especially during longer periods of refrigerated storage. Limiting the refrigerated storage period to the manufacturer-recommended 24 hours will limit particulate formation.

  9. [Pharmaceutical research progress of rhynchophylla based on chemical stability].

    Science.gov (United States)

    Hao, Bo; Yang, Xiu-Juan; Feng, Yi; Hong, Yan-Long

    2014-12-01

    Rhynchophylla is a Chinese herb commonly used in clinical practice. It's also the primary herb of some famous Chinese herbal compound such as Tianma Gouteng decoction, and Lingyang Gouteng decoction. According the record from many previous materia medica literatures, rhynchophylla should be added later during decoction. Pharmaceutical research showed that rhynchophylla alkaloids were not stable. Which has resulted in many problems in the research and its application. For example, there was not a quantitative determination method in "Chinese Pharmacopoeia" of past and present versions, which seriously impacted its quality control and product application. Firstly, records from previous materia medica literatures and "Chinese Pharmacopoeia" were systematically sorted based on the chemical stability of rhynchophylla. Secondly, pharmaceutical research including chemical compositions and their stability, pharmacological effects, extraction process and quality analysis, was reviewed after reference of literatures published at home and abroad in recent decades. Positive reference and evidence for further research and development of rhynchophylla will be provided in the article.

  10. Physical and chemical stability of different formulations with superoxide dismutase.

    Science.gov (United States)

    Di Mambro, V M; Campos, P M B G Maia; Fonseca, M J V

    2004-10-01

    Topical formulations with superoxide dismutase (SOD), a scavenger of superoxide radicals, have proved to be effective against some skin diseases. Nevertheless, formulations with proteins are susceptible to both chemical and physical instability. Three different formulations (anionic and non-ionic gel and emulsion) were developed and supplemented with SOD in order to determine the most stable formulation that would maintain SOD activity. Physical stability was evaluated by assessing the rheological behavior of the formulations stored at room temperature, 37 and 45 degrees C. Chemical stability was evaluated by the measurement of enzymatic activity in the formulations stored at room temperature and at 45 degrees C. Formulations showed a flow index less than one, characterizing pseudoplastic behavior. There was no significant difference in initial values of flow index, tixotropy or minimum apparent viscosity. Neither gel showed significant changes in minimum apparent viscosity concerning storage time or temperature, as well, SOD presence and its activity. The emulsion showed decreased viscosity by the 28th day, but no significant changes concerning storage temperature or SOD presence, although it showed a decreased activity. The addition of SOD to the formulations studied did not affect their physical stability but gel formulations seem to be better bases for enzyme addition.

  11. Chemical synthesis and stabilization of magnesium substituted brushite

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Donghyun [Department of Biomedical Engineering, Chung-Ang University, 221 Heukseok-Dong, Dongjak-Gu, Seoul 156-756 (Korea, Republic of); Kumta, Prashant N., E-mail: pkumta@pitt.edu [Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA 15260 (United States); Department of Mechanical Engineering and Materials Sceince, University of Pittsburgh, Pittsburgh, PA 15260 (United States); Department of Chemical and Petroleum Engineering, University of Pittsburgh, Pittsburgh, PA 15260 (United States)

    2010-08-30

    Hydroxyapatite (Ca{sub 10}(PO{sub 4}){sub 6}(OH){sub 2}) is the most ubiquitous calcium phosphate phase used in implant coatings and more recently in gene/drug delivery applications due to its chemical stability under normal physiological conditions (37 deg. C, pH {approx} 7.5, 1 atm.). However, different calcium phosphate phases, such as brushite (CaH(PO{sub 4}){center_dot}2(H{sub 2}O)) and tricalcium phosphate (Ca{sub 3}(PO{sub 4}){sub 2}) which are thermodynamically unstable under physiological conditions are also being explored for biomedical applications. One way of stabilizing these phases under physiological conditions is to introduce magnesium to substitute for calcium in the brushite lattice. The role of magnesium as a stabilizing agent for synthesizing brushite under physiological conditions at room temperature has been studied. Chemical analysis, Fourier transform infrared spectroscopy and X-ray diffraction have also been conducted to validate the formation of magnesium substituted brushite under physiological conditions.

  12. Chemically stabilized epitaxial wurtzite-BN thin film

    Science.gov (United States)

    Vishal, Badri; Singh, Rajendra; Chaturvedi, Abhishek; Sharma, Ankit; Sreedhara, M. B.; Sahu, Rajib; Bhat, Usha; Ramamurty, Upadrasta; Datta, Ranjan

    2018-03-01

    We report on the chemically stabilized epitaxial w-BN thin film grown on c-plane sapphire by pulsed laser deposition under slow kinetic condition. Traces of no other allotropes such as cubic (c) or hexagonal (h) BN phases are present. Sapphire substrate plays a significant role in stabilizing the metastable w-BN from h-BN target under unusual PLD growth condition involving low temperature and pressure and is explained based on density functional theory calculation. The hardness and the elastic modulus of the w-BN film are 37 & 339 GPa, respectively measured by indentation along direction. The results are extremely promising in advancing the microelectronic and mechanical tooling industry.

  13. Color stabilization of red wines. A chemical and colloidal approach.

    Science.gov (United States)

    Alcalde-Eon, Cristina; García-Estévez, Ignacio; Puente, Victor; Rivas-Gonzalo, Julián C; Escribano-Bailón, M Teresa

    2014-07-23

    The effects of cold treatment and time on CIELAB color parameters and on anthocyanin and anthocyanin-derived pigments composition have been evaluated as has been the effectiveness of either an enological tannin or a mannoprotein (M) on their stabilization. With respect to color, hue (hab) was increased in the wines treated with both enological products. Furthermore, the color changes induced by cold treatment were lessened by the addition of these two enological products, although the protective effect was higher for the wines treated with M. The pigment analysis revealed higher percentages of anthocyanin-derived pigments in tannin and M-treated samples (in both cold treated and not) in relation to control ones. The addition of the enological tannin may favor the synthesis of anthocyanin-derived pigments, which are chemically more stable than native anthocyanins, whereas M seems to stabilize anthocyanin-derived pigments from a colloidal point of view, avoiding their aggregation and further precipitation.

  14. Organo-mineral interactions promote greater soil organic carbon stability under aspen in semi-arid montane forests in Utah

    Science.gov (United States)

    Van Miegroet, H.; Roman Dobarco, M.

    2014-12-01

    Forest species influence soil organic carbon (SOC) storage through litter input, which in interaction with soil microclimate, texture and mineralogy, lead to different SOC stabilization and storage patterns. We sampled mineral soil (0-15 cm) across the ecotone between aspen (Populus tremuloides) and mixed conifers stands (Abies lasiocarpa and Pseudotsuga menziesii) in semi-arid montane forests from Utah, to investigate the influence of vegetation vs. site characteristics on SOC stabilization, storage and chemistry. SOC was divided into light fraction (LF), mineral-associated SOC in the silt and clay fraction (MoM), and a dense subfraction > 53 μm (SMoM) using wet sieving and electrostatic attraction. SOC decomposability and solubility was derived from long term laboratory incubations and hot water extractions (HWE). Fourier transform infrared spectroscopy (FTIR) was used to study differences in chemical functional groups in LF and MoM. Vegetation cover did not affect SOC storage (47.0 ± 16.5 Mg C ha-1), SOC decomposability (cumulative CO2-C release of 93.2 ± 65.4 g C g-1 C), or SOC solubility (9.8 ± 7.2 mg C g-1 C), but MoM content increased with presence of aspen [pure aspen (31.2 ± 15.1 Mg C ha-1) > mixed (25.7 ± 8.8 Mg C ha-1) > conifer (22.8 ± 9.0 Mg C ha-1)]. Organo-mineral complexes reduced biological availability of SOC, indicated by the negative correlation between silt+clay (%) and decomposable SOC per gram of C (r = -0.48, p = 0.001) or soluble SOC (r = -0.59, p plant or microbial origin. FTIR spectra clustered by sites with similar parent material rather than by vegetation cover. This suggests that initial differences in litter chemistry between aspen and conifers converged into similar MoM chemistry within sites.

  15. Examination of lignocellulosic fibers for chemical, thermal, and separations properties: Addressing thermo-chemical stability issues

    Science.gov (United States)

    Johnson, Carter David

    Natural fiber-plastic composites incorporate thermoplastic resins with fibrous plant-based materials, sometimes referred to as biomass. Pine wood mill waste has been the traditional source of natural fibrous feedstock. In anticipation of a waste wood shortage other fibrous biomass materials are being investigated as potential supplements or replacements. Perennial grasses, agricultural wastes, and woody biomass are among the potential source materials. As these feedstocks share the basic chemical building blocks; cellulose, hemicellulose, and lignin, they are collectively called lignocellulosics. Initial investigation of a number of lignocellulosic materials, applied to fiber-plastic composite processing and material testing, resulted in varied results, particularly response to processing conditions. Less thermally stable lignocellulosic filler materials were physically changed in observable ways: darkened color and odor. The effect of biomass materials' chemical composition on thermal stability was investigated an experiment involving determination of the chemical composition of seven lignocellulosics: corn hull, corn stover, fescue, pine, soy hull, soy stover, and switchgrass. These materials were also evaluated for thermal stability by thermogravimetric analysis. The results of these determinations indicated that both chemical composition and pretreatment of lignocellulosic materials can have an effect on their thermal stability. A second study was performed to investigate what effect different pretreatment systems have on hybrid poplar, pine, and switchgrass. These materials were treated with hot water, ethanol, and a 2:1 benzene/ethanol mixture for extraction times of: 1, 3, 6, 12, and 24 hours. This factorial experiment demonstrated that both extraction time and medium have an effect on the weight percent of extractives removed from all three material types. The extracted materials generated in the above study were then subjected to an evaluation of thermal

  16. Chemical stability of reactive skin decontamination lotion (RSDL®).

    Science.gov (United States)

    Bogan, R; Maas, H J; Zimmermann, T

    2018-09-01

    Reactive Skin Decontamination Lotion (RSDL ® ) is used for the decontamination of Chemical Warfare Agents and Toxic Industrial Compounds after dermal exposure. It has to be stockpiled over a long period and is handled in all climatic zones. Therefore stability is an essential matter of concern. In this work we describe a study to the chemical stability of RSDL ® as basis for an estimation of shelf life. We analysed RSDL ® for the active ingredient 2,3-butandione monoxime (diacetylmonooxime, DAM), the putative degradation product dimethylglyoxime (DMG) and unknown degradation products by means of a reversed phase high pressure liquid chromatography (HPLC). Calculations were done according to the Arrhenius equation. Based on the temperature dependent rate constants, the time span was calculated, until defined threshold values for DAM and DMG subject to specification and valid regulations were exceeded. The calculated data were compared to the ones gathered from stockpiled samples and samples exposed during foreign mission. The decline of DAM followed first order kinetics, while formation of DMG could be described by zero order kinetics. The rate constants were distinctively temperature dependent. Calculated data were in good accordance to the measured ones from stockpile and mission. Based on a specified acceptable DAM-content of 90% and a valid threshold value of 0.1% (w/w) for the degradation product DMG, RSDL ® proved to be stable for at least four years if stored at the recommended conditions of 15°C-30°C. If continuously stored at higher temperatures shelf life will decrease markedly. Therefore RSDL ® is an object for risk orientated quality monitoring during storage. Copyright © 2017 Elsevier B.V. All rights reserved.

  17. Reflow process stabilization by chemical characteristics and process conditions

    Science.gov (United States)

    Kim, Myoung-Soo; Park, Jeong-Hyun; Kim, Hak-Joon; Kim, Il-Hyung; Jeon, Jae-Ha; Gil, Myung-Goon; Kim, Bong-Ho

    2002-07-01

    With the shrunken device rule below 130nm, the patterning of smaller contact hole with enough process margin is required for mass production. Therefore, shrinking technology using thermal reflow process has been applied for smaller contact hole formation. In this paper, we have investigated the effects of chemical characteristics such as molecular weight, blocking ratio of resin, cross-linker amount and solvent type with its composition to reflow process of resist and found the optimized chemical composition for reflow process applicable condition. And several process conditions like resist coating thickness and multi-step thermal reflow method have been also evaluated to stabilize the pattern profile and improve CD uniformity after reflow process. From the experiment results, it was confirmed that the effect of crosslinker in resist to reflow properties such as reflow temperature and reflow rate were very critical and it controlled the pattern profile during reflow processing. And also, it showed stable CD uniformity and improved resist properties for top loss, film shrinkage and etch selectivity. The application of lower coating thickness of resist induced symmetric pattern profile even at edge with wider process margin. The introduction of two-step baking method for reflow process showed uniform CD value, also. It is believed that the application of resist containing crosslinker and optimized process conditions for smaller contact hole patterning is necessary for the mass production with a design rule below 130nm.

  18. Color stability and staining of silorane after prolonged chemical challenges

    DEFF Research Database (Denmark)

    de Jesus, Vivian CBR; Martinelli, Nata Luiz; Poli-Frederico, Regina Célia

    Objectives: The purpose of this study was to investigate the effect of prolonged chemical challenges on color stability and staining susceptibility of a silorane-based composite material when compared to methacrylate-based composites. Methods: Cylindrical specimens (n=24) were fabricated from...... methacrylate (Filtek Z250, 3M ESPE; Filtek Z350XT, 3M ESPE; Master Fill, Biodinâmica) or silorane-based (Filtek P90, 3M ESPE) composite materials. Initial color was registered in a spectrophotometer. Specimens were divided in four groups and individually stored at 37°C in 0.02N citric acid, 0.02N phosphoric...... acid, 75% ethanol or distilled water (control) for 7, 14, 21, and 180 days, when new measurements were performed. A staining test was performed (n=12) after 21 days of chemical challenge by immersion in coffee during 3 weeks at 37°C. Color changes (¿E) were characterized using the CIEL*a*b* color...

  19. Pyrochlore as nuclear waste form. Actinide uptake and chemical stability

    Energy Technology Data Exchange (ETDEWEB)

    Finkeldei, Sarah Charlotte

    2015-07-01

    Radioactive waste is generated by many different technical and scientific applications. For the past decades, different waste disposal strategies have been considered. Several questions on the waste disposal strategy remain unanswered, particularly regarding the long-term radiotoxicity of minor actinides (Am, Cm, Np), plutonium and uranium. These radionuclides mainly arise from high level nuclear waste (HLW), specific waste streams or dismantled nuclear weapons. Although many countries have opted for the direct disposal of spent fuel, from a scientific and technical point of view it is imperative to pursue alternative waste management strategies. Apart from the vitrification, especially for trivalent actinides and Pu, crystalline ceramic waste forms are considered. In contrast to glasses, crystalline waste forms, which are chemically and physically highly stable, allow the retention of radionuclides on well-defined lattice positions within the crystal structure. Besides polyphase ceramics such as SYNROC, single phase ceramics are considered as tailor made host phases to embed a specific radionuclide or a specific group. Among oxidic single phase ceramics pyrochlores are known to have a high potential for this application. This work examines ZrO{sub 2} based pyrochlores as potential nuclear waste forms, which are known to show a high aqueous stability and a high tolerance towards radiation damage. This work contributes to (1) understand the phase stability field of pyrochlore and consequences of non-stoichiometry which leads to pyrochlores with mixed cationic sites. Mixed cationic occupancies are likely to occur in actinide-bearing pyrochlores. (2) The structural uptake of radionuclides themselves was studied. (3) The chemical stability and the effect of phase transition from pyrochlore to defect fluorite were probed. This phase transition is important, as it is the result of radiation damage in ZrO{sub 2} based pyrochlores. ZrO{sub 2} - Nd{sub 2}O{sub 3} pellets

  20. Pyrochlore as nuclear waste form. Actinide uptake and chemical stability

    International Nuclear Information System (INIS)

    Finkeldei, Sarah Charlotte

    2015-01-01

    Radioactive waste is generated by many different technical and scientific applications. For the past decades, different waste disposal strategies have been considered. Several questions on the waste disposal strategy remain unanswered, particularly regarding the long-term radiotoxicity of minor actinides (Am, Cm, Np), plutonium and uranium. These radionuclides mainly arise from high level nuclear waste (HLW), specific waste streams or dismantled nuclear weapons. Although many countries have opted for the direct disposal of spent fuel, from a scientific and technical point of view it is imperative to pursue alternative waste management strategies. Apart from the vitrification, especially for trivalent actinides and Pu, crystalline ceramic waste forms are considered. In contrast to glasses, crystalline waste forms, which are chemically and physically highly stable, allow the retention of radionuclides on well-defined lattice positions within the crystal structure. Besides polyphase ceramics such as SYNROC, single phase ceramics are considered as tailor made host phases to embed a specific radionuclide or a specific group. Among oxidic single phase ceramics pyrochlores are known to have a high potential for this application. This work examines ZrO 2 based pyrochlores as potential nuclear waste forms, which are known to show a high aqueous stability and a high tolerance towards radiation damage. This work contributes to (1) understand the phase stability field of pyrochlore and consequences of non-stoichiometry which leads to pyrochlores with mixed cationic sites. Mixed cationic occupancies are likely to occur in actinide-bearing pyrochlores. (2) The structural uptake of radionuclides themselves was studied. (3) The chemical stability and the effect of phase transition from pyrochlore to defect fluorite were probed. This phase transition is important, as it is the result of radiation damage in ZrO 2 based pyrochlores. ZrO 2 - Nd 2 O 3 pellets with pyrochlore and defect

  1. Chemical derivatization to enhance chemical/oxidative stability of resorcinol-formaldehyde resin

    Energy Technology Data Exchange (ETDEWEB)

    Hubler, T.L. [Pacific Northwest National Lab., Richland, WA (United States)

    1997-10-01

    The goal of this task is to develop modified resorcinol-formaldehyde (R-F) resin to improve the chemical/oxidative stability of the resin. R-F resin is a regenerable organic ion-exchange resin that is selective for cesium ion in highly alkaline, high ionic-strength solutions. R-F resin tends to undergo chemical degradation, reducing its ability to remove cesium ion from waste solutions; the mechanistic details of these decomposition reactions are currently unknown. The approach used for this task is chemical modification of the resin structure, particularly the resorcinol ring unit of the polymer resin. This approach is based on prior characterization studies conducted at Pacific Northwest National Laboratory (PNNL) that indicated the facile chemical degradation of the resin is oxidation of the resorcinol ring to the para-quinone structure, with subsequent loss of ion-exchange sites for cesium ion. R-F resin represents an important alternative to current radiocesium remediation technology for tank wastes at both the Hanford and Savannah River sites, particularly if regenerable resins are needed.

  2. Chemical stability and physical properties of Caesium uranates

    International Nuclear Information System (INIS)

    Berton, J.P.; Baron, D.; Coquerelle, M.

    1998-01-01

    Caesium is one of the most abundant fission products in PWR nuclear fuel or in fast reactor fuel as well. A work program has been started at the TUI Karlsruhe, in collaboration with EDF Etudes et Recherches, to determine the thermal stability and conductivity, the mechanical properties and the thermal expansion coefficient of Cs 2 UO 4 . The Caesium mono-uranate was obtained by a chemical reaction between Cs 2 O 3 and U 3 O 8 powders mixed together, pressed and heated at 670 deg. C for 24 hours. The compound was found stable up to 830 deg. C. Mechanical compressive hardening tests allowed to evaluate the elastic modulus versus temperature in the range 200 to 800 deg. C. Furthermore the viscous behaviour of the compound above 400 deg. C was confirmed. The thermal expansion coefficient of Cs 2 UO 4 was found somewhat 40% higher than the thermal expansion coefficient of UO 2 . The thermal conductivity is about 1.5 to 1.8 W/m/K for temperatures ranging from 100 to 700 deg. C, a value very similar to the UO 2 fuel thermal conductivity at high burnup in the same temperature range. (author)

  3. Chemical vapor deposition of yttria stabilized zirconia in porous substrates

    International Nuclear Information System (INIS)

    Carolan, M.F.; Michaels, J.N.

    1987-01-01

    Electrochemical vapor deposition (EVD) of yttria stabilized zirconia (YSZ) is the preferred route to the production of thin films of YSZ on porous substrates. This process has been used in the construction of both fuel cells and steam electrolyzers. A critical aspect of the EVD process is an initial chemical vapor deposition phase in which the pores of a porous substrate are plugged by YSZ. In this process, water vapor and a mixture of gaseous zirconium chloride and yttrium chloride diffuse into the porous substrate from opposite sides and react to form YSZ and HCl ga. During the second stage of the process a continuous dense film of electrolyte is formed by a tarnishing-type process. Experimentally it is observed that the pores plug within a few pore diameters of the metal chloride face of the substrate. A kinetic rate expression that is first order in metal chloride but zero order in water is best able to explain this phenomenon. With this rate expression, the pores always plug near the metal chloride face. The model predicts less pore narrowing to occur as the ratio of the reaction rate to the diffusion rate of the metal chloride is increased. A kinetic rate expression that is first order in both water and metal chloride predicts that the pores plug much deeper in the substrate

  4. Method of waste stabilization with dewatered chemically bonded phosphate ceramics

    Science.gov (United States)

    Wagh, Arun; Maloney, Martin D.

    2010-06-29

    A method of stabilizing a waste in a chemically bonded phosphate ceramic (CBPC). The method consists of preparing a slurry including the waste, water, an oxide binder, and a phosphate binder. The slurry is then allowed to cure to a solid, hydrated CBPC matrix. Next, bound water within the solid, hydrated CBPC matrix is removed. Typically, the bound water is removed by applying heat to the cured CBPC matrix. Preferably, the quantity of heat applied to the cured CBPC matrix is sufficient to drive off water bound within the hydrated CBPC matrix, but not to volatalize other non-water components of the matrix, such as metals and radioactive components. Typically, a temperature range of between 100.degree. C.-200.degree. C. will be sufficient. In another embodiment of the invention wherein the waste and water have been mixed prior to the preparation of the slurry, a select amount of water may be evaporated from the waste and water mixture prior to preparation of the slurry. Another aspect of the invention is a direct anyhydrous CBPC fabrication method wherein water is removed from the slurry by heating and mixing the slurry while allowing the slurry to cure. Additional aspects of the invention are ceramic matrix waste forms prepared by the methods disclosed above.

  5. Chemical, computational and functional insights into the chemical stability of the Hedgehog pathway inhibitor GANT61.

    Science.gov (United States)

    Calcaterra, Andrea; Iovine, Valentina; Botta, Bruno; Quaglio, Deborah; D'Acquarica, Ilaria; Ciogli, Alessia; Iazzetti, Antonia; Alfonsi, Romina; Lospinoso Severini, Ludovica; Infante, Paola; Di Marcotullio, Lucia; Mori, Mattia; Ghirga, Francesca

    2018-12-01

    This work aims at elucidating the mechanism and kinetics of hydrolysis of GANT61, the first and most-widely used inhibitor of the Hedgehog (Hh) signalling pathway that targets Glioma-associated oncogene homologue (Gli) proteins, and at confirming the chemical nature of its bioactive form. GANT61 is poorly stable under physiological conditions and rapidly hydrolyses into an aldehyde species (GANT61-A), which is devoid of the biological activity against Hh signalling, and a diamine derivative (GANT61-D), which has shown inhibition of Gli-mediated transcription. Here, we combined chemical synthesis, NMR spectroscopy, analytical studies, molecular modelling and functional cell assays to characterise the GANT61 hydrolysis pathway. Our results show that GANT61-D is the bioactive form of GANT61 in NIH3T3 Shh-Light II cells and SuFu -/- mouse embryonic fibroblasts, and clarify the structural requirements for GANT61-D binding to Gli1. This study paves the way to the design of GANT61 derivatives with improved potency and chemical stability.

  6. Use of the GREAT-ER model to estimate mass fluxes of chemicals, carried into the Western Scheldt estuary from the Rupel basin

    OpenAIRE

    Schowanek, D.

    2002-01-01

    The poster illustrates the application of the GREAT-ER model to estimate the mass flux of chemicals carried from a river basin into an estuary. GREAT-ER (Geo-referenced Regional Exposure Assessment Tool for European Rivers) is a newly developed model (1999) for management and risk assessment of chemicals in river basins (see www.great-er.org). Recently the Rupel basin has been made available for use within GREAT-ER. This now allows to make a reliable estimation of the contribution of pollu...

  7. Triphenylamine - a 'new' stabilizer for nitrocellulose based propellants. Pt. 1: chemical stability studies

    Energy Technology Data Exchange (ETDEWEB)

    Wilker, Stephan; Heeb, Gerhard [WIWEB ASt Heimerzheim, Grosses Cent, 53913 Swisttal (Germany); Vogelsanger, Beat [Nitrochemie Wimmis AG, Niesenstr. 44, 3752 Wimmis (Switzerland); Petrzilek, Jan; Skladal, Jan [Explosia a.s. - Research Institute of Industrial Chemistry (VUPCH), 532 17 Pardubice (Czech Republic)

    2007-04-15

    Triphenylamine (TPA) was used for the first time in France in 1937 as a stabilizer for propellants. The stability of those samples was described as 'good'. Around 1950 an American group produced TPA stabilized propellants and investigated the decomposition mechanism. Apart from one single experiment in the 1970s no further attempts were made to take TPA as a stabilizer for propellants. With the background of an increasingly critical discussion about nitrosamines in propellants and their declaration of being carcinogenic, TPA revealed a renaissance since the year 2000. To achieve the goal of nitrosamine free propellants several TPA stabilized propellants were produced. Their processability, stability and ballistic properties were investigated. This publication summarizes the most important results of stability tests on more than 30 different TPA stabilized propellants including the decomposition mechanism, the synthesis of the consecutive products and their stabilizing properties. In addition, the internal compatibility of TPA with the most important propellant ingredients is discussed and its relative decomposition rate is compared with that of other stabilizers. In summary TPA is a suitable stabilizer for propellants. It has nevertheless two disadvantages. It is relatively rapidly consumed in double base formulations (which makes it difficult to pass the criteria of AOP-48, Ed. 2) and the stabilizing activity of the two major consecutive products 4-NO{sub 2}-TPA and especially 4,4{sup '}-di-NO{sub 2}-TPA is low. (Abstract Copyright [2007], Wiley Periodicals, Inc.)

  8. Physical and chemical stability of the bentonite buffer

    Energy Technology Data Exchange (ETDEWEB)

    Jinsong Liu; Neretnieks, Ivars [Chemical Engineering and Technology, Royal I nstitute of Technology, Stockholm (Sweden)

    2007-12-15

    A literature study was made on previous work on clay erosion and on the fundamental processes that govern the stability of clay gels. Mechanical erosion has been studied earlier and models devised to estimate the tendency to erode. We have used a different approach that we deem is fundamentally more correct. Chemical erosion processes have not been found to be studied previously and we have approached the problem by applying simple but fundamental mass balances and transport processes to the problem. The physical and chemical processes that govern the repulsive and cohesive forces in clay are well understood in principle but cannot yet be applied quantitatively to predict the gel/sol behaviour of the bentonite clay. It was necessary to rely directly on laboratory measurements for information on swelling and gel/sol properties. The backfill bentonite clay acts as a Bingham fluid over a wide range of clay density. To mobilise the clay a shear stress larger than the Bingham yield stress must be applied to the gel. The Bingham yield stress has been measured to be larger than 1 Pa (N/m{sup 2}) although it cannot be ruled out that lower values can be found under different experimental conditions than those reported. Shear stresses exerted by the water flowing in the fractures that intersect the deposition holes with the clay backfill have been estimated for a wide range of fracture transmissivities, apertures and hydraulic gradients that could exist under repository conditions. This includes the extremely high gradients that could exist during some periods during an ice age. For fracture transmissivities ranging from 10{sup -9} to 10{sup -6} m{sup 2}/s, fracture apertures from 0.1 to 2 mm and the hydraulic gradients from 0.01 to 1 mH{sub 2}O/m, the largest local shear stress found in this range was about 0.1 Pa. To investigate a 'what if' situation where the shear stress exceeds the yield stress simple models were devised. They were used to assess the rate of

  9. Physical and chemical stability of the bentonite buffer

    International Nuclear Information System (INIS)

    Jinsong Liu; Neretnieks, Ivars

    2007-12-01

    A literature study was made on previous work on clay erosion and on the fundamental processes that govern the stability of clay gels. Mechanical erosion has been studied earlier and models devised to estimate the tendency to erode. We have used a different approach that we deem is fundamentally more correct. Chemical erosion processes have not been found to be studied previously and we have approached the problem by applying simple but fundamental mass balances and transport processes to the problem. The physical and chemical processes that govern the repulsive and cohesive forces in clay are well understood in principle but cannot yet be applied quantitatively to predict the gel/sol behaviour of the bentonite clay. It was necessary to rely directly on laboratory measurements for information on swelling and gel/sol properties. The backfill bentonite clay acts as a Bingham fluid over a wide range of clay density. To mobilise the clay a shear stress larger than the Bingham yield stress must be applied to the gel. The Bingham yield stress has been measured to be larger than 1 Pa (N/m 2 ) although it cannot be ruled out that lower values can be found under different experimental conditions than those reported. Shear stresses exerted by the water flowing in the fractures that intersect the deposition holes with the clay backfill have been estimated for a wide range of fracture transmissivities, apertures and hydraulic gradients that could exist under repository conditions. This includes the extremely high gradients that could exist during some periods during an ice age. For fracture transmissivities ranging from 10 -9 to 10 -6 m 2 /s, fracture apertures from 0.1 to 2 mm and the hydraulic gradients from 0.01 to 1 mH 2 O/m, the largest local shear stress found in this range was about 0.1 Pa. To investigate a 'what if' situation where the shear stress exceeds the yield stress simple models were devised. They were used to assess the rate of erosion by the groundwater. In

  10. Stabilization of low-level mixed waste in chemically bonded phosphate ceramics

    International Nuclear Information System (INIS)

    Wagh, A.S.; Singh, D.; Sarkar, A.V.

    1994-06-01

    Mixed waste streams, which contain both chemical and radioactive wastes, are one of the important categories of DOE waste streams needing stabilization for final disposal. Recent studies have shown that chemically bonded phosphate ceramics may have the potential for stabilizing these waste streams, particularly those containing volatiles and pyrophorics. Such waste streams cannot be stabilized by conventional thermal treatment methods such as vitrification. Phosphate ceramics may be fabricated at room temperature into durable, hard and dense materials. For this reason room-temperature-setting phosphate ceramic waste forms are being developed to stabilize these to ''problem waste streams.''

  11. Greater Role of Geostrophic Currents on Ekman Dynamics in the Western Arctic Ocean as a Mechanism for Beaufort Gyre Stabilization

    Science.gov (United States)

    Steele, M.; Zhong, W.; Zhang, J.; Zhao, J.

    2017-12-01

    Seven different methods, with and without including geostrophic currents, were used to explore Ekman dynamics in the western Arctic Ocean for the period 1992-2014. Results show that surface geostrophic currents have been increasing and are much stronger than Ekman layer velocities in recent years (2003-2014) when the oceanic Beaufort Gyre (BG) is spinning up in the region. The new methods that include geostrophic currents result in more realistic Ekman pumping velocities than a previous iterative method that does not consider geostrophic currents and therefore overestimates Ekman pumping velocities by up to 52% in the central area of the BG over the period 2003-2014. When the BG is spinning up as seen in recent years, geostrophic currents become stronger, which tend to modify the ice-ocean stress and to cause an Ekman divergence that counteracts wind-driven Ekman convergence in the Canada Basin. This is a mechanism we have identified to play an important and growing role in stabilizing the Ekman convergence and therefore the BG in recent years. This mechanism may be used to explain three scenarios that describe the interplay of changes in wind forcing, sea ice motion, and geostrophic currents that control the variability of the Ekman dynamics in the central BG during 1992-2014. Results also reveal several upwelling regions in the southern and northern Canada Basin and the Chukchi Abyssal Plain which may plays a significant role in biological processes in these regions.

  12. Greater Role of Geostrophic Currents in Ekman Dynamics in the Western Arctic Ocean as a Mechanism for Beaufort Gyre Stabilization

    Science.gov (United States)

    Zhong, Wenli; Steele, Michael; Zhang, Jinlun; Zhao, Jinping

    2018-01-01

    Seven different methods, with and without including geostrophic currents, were used to explore Ekman dynamics in the western Arctic Ocean for the period 1992-2014. Results show that surface geostrophic currents have been increasing and are much stronger than Ekman layer velocities in recent years (2003-2014) when the oceanic Beaufort Gyre (BG) is spinning up in the region. The new methods that include geostrophic currents result in more realistic Ekman pumping velocities than a previous iterative method that does not consider geostrophic currents and therefore overestimates Ekman pumping velocities by up to 52% in the central area of the BG over the period 2003-2014. When the BG is spinning up as seen in recent years, geostrophic currents become stronger, which tend to modify the ice-ocean stress and moderate the wind-driven Ekman convergence in the Canada Basin. This is a mechanism we have identified to play an important and growing role in stabilizing the Ekman convergence and therefore the BG in recent years. This mechanism may be used to explain three scenarios that describe the interplay of changes in wind forcing, sea ice motion, and geostrophic currents that control the variability of the Ekman dynamics in the central BG during 1992-2014. Results also reveal several upwelling regions in the southern and northern Canada Basin and the Chukchi Abyssal Plain which may play a significant role in physical and biological processes in these regions.

  13. Annulated Dialkoxybenzenes as Catholyte Materials for Non-aqueous Redox Flow Batteries: Achieving High Chemical Stability through Bicyclic Substitution

    International Nuclear Information System (INIS)

    Zhang, Jingjing; Yang, Zheng; Shkrob, Ilya A.; Assary, Rajeev S.

    2017-01-01

    1,4-Dimethoxybenzene derivatives are materials of choice for use as catholytes in nonaqueous redox flow batteries, as they exhibit high open-circuit potentials and excellent electrochemical reversibility. However, chemical stability of these materials in their oxidized form needs to be improved. Disubstitution in the arene ring is used to suppress parasitic reactions of their radical cations, but this does not fully prevent ring-addition reactions. By incorporating bicyclic substitutions and ether chains into the dialkoxybenzenes, a novel catholyte molecule, 9,10-bis(2-methoxyethoxy)-1,2,3,4,5,6,7,8-octahydro-1,4:5, 8-dimethanenoanthracene (BODMA), is obtained and exhibits greater solubility and superior chemical stability in the charged state. As a result, a hybrid flow cell containing BODMA is operated for 150 charge–discharge cycles with minimal loss of capacity.

  14. Both solubility and chemical stability of curcumin are enhanced by solid dispersion in cellulose derivative matrices.

    Science.gov (United States)

    Li, Bin; Konecke, Stephanie; Wegiel, Lindsay A; Taylor, Lynne S; Edgar, Kevin J

    2013-10-15

    Amorphous solid dispersions (ASD) of curcumin (Cur) in cellulose derivative matrices, hydroxypropylmethylcellulose acetate succinate (HPMCAS), carboxymethylcellulose acetate butyrate (CMCAB), and cellulose acetate adipate propionate (CAAdP) were prepared in order to investigate the structure-property relationship and identify polymer properties necessary to effectively increase Cur aqueous solution concentration. XRD results indicated that all investigated solid dispersions were amorphous, even at a 9:1 Cur:polymer ratio. Both stability against crystallization and Cur solution concentration from these ASDs were significantly higher than those from physical mixtures and crystalline Cur. Remarkably, curcumin was also stabilized against chemical degradation in solution. Chemical stabilization was polymer-dependent, with stabilization in CAAdP>CMCAB>HPMCAS>PVP, while matrices enhanced solution concentration as PVP>HPMCAS>CMCAB≈CAAdP. HPMCAS/Cur dispersions have useful combinations of pH-triggered release profile, chemical stabilization, and strong enhancement of Cur solution concentration. Copyright © 2013 Elsevier Ltd. All rights reserved.

  15. Thermal stability of chemically denatured green fluorescent protein (GFP) A preliminary study

    Energy Technology Data Exchange (ETDEWEB)

    Nagy, Attila; Malnasi-Csizmadia, Andras; Somogyi, Bela; Lorinczy, Denes

    2004-02-09

    Green fluorescent protein (GFP) is a light emitter in the bioluminescence reaction of the jellyfish Aequorea victoria. The protein consist of 238 amino acids and produces green fluorescent light ({lambda}{sub max}=508 nm), when irradiated with near ultraviolet light. The fluorescence is due to the presence of chromophore consisting of an imidazolone ring, formed by a post-translational modification of the tripeptide -Ser{sup 65}-Tyr{sup 66}-Gly{sup 67}-, which buried into {beta}-barrel. GFP is extremely compact and heat stable molecule. In this work, we present data for the effect of chemical denaturing agent on the thermal stability of GFP. When denaturing agent is applied, global thermal stability and the melting point of the molecule is decreases, that can be monitored with differential scanning calorimetry. The results indicate, that in 1-6 M range of GuHCl the melting temperature is decreasing continuously from 83 to 38 deg. C. Interesting finding, that the calculated calorimetric enthalpy decreases with GuHCl concentration up to 3 M (5.6-0.2 kJ mol{sup -1}), but at 4 M it jumps to 8.4 and at greater concentration it is falling down to 1.1 kJ mol{sup -1}. First phenomena, i.e. the decrease of melting point with increasing GuHCl concentration can be easily explained by the effect of the extended chemical denaturation, when less and less amount of heat required to diminish the remaining hydrogen bonds in {beta}-barrel. The surprising increase of calorimetric enthalpy at 4 M concentration of GuHCl could be the consequence of a dimerization or a formation of stable complex between GFP and denaturing agent as well as a precipitation at an extreme GuHCl concentration. We are planning further experiments to elucidate fluorescent consequence of these processes.

  16. Long term physical and chemical stability of polyelectrolyte multilayer membranes

    NARCIS (Netherlands)

    de Grooth, Joris; Haakmeester, Brian; Wever, Carlos; Potreck, Jens; de Vos, Wiebe Matthijs; Nijmeijer, Dorothea C.

    2015-01-01

    This work presents a detailed investigation into the long term stability of polyelectrolyte multilayer (PEM) modified membranes, a key factor for the application of these membranes in water purification processes. Although PEM modified membranes have been frequently investigated, their long term

  17. Study on stability of a-SiCOF films deposited by plasma enhanced chemical vapor deposition

    International Nuclear Information System (INIS)

    Ding Shijin; Zhang Qingquan; Wang Pengfei; Zhang Wei; Wang Jitao

    2001-01-01

    Low-dielectric-constant a-SiCOF films have been prepared from TEOS, C 4 F 8 and Ar by using plasma enhanced chemical vapor deposition method. With the aid of X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR), the chemical bonding configuration, thermal stability and resistance to water of the films are explored

  18. Chemical stability of copper-canisters in deep repository

    International Nuclear Information System (INIS)

    Ahonen, L.

    1995-12-01

    The spent fuel from Finnish nuclear reactors is planned to be encapsulated in thick-walled copper-iron canisters and placed deep into the bedrock. The copper wall of the canister provides a long-time shield against corrosion, preventing the high-level nuclear fuel from contact with ground water. In the report, stability of metallic copper and its possible corrosion reactions in the conditions of deep bedrock are evaluated by means of thermo-dynamic calculations. (90 refs., 28 figs., 11 tabs.)

  19. Vibration and Stability of 3000-hp, Titanium Chemical Process Blower

    Directory of Open Access Journals (Sweden)

    Les Gutzwiller

    2003-01-01

    Full Text Available This 74-in-diameter blower had an overhung rotor design of titanium construction, operating at 50 pounds per square inch gauge in a critical chemical plant process. The shaft was supported by oil-film bearings and was directdriven by a 3000-hp electric motor through a metal disk type of coupling. The operating speed was 1780 rpm. The blower shaft and motor shaft motion was monitored by Bently Nevada proximity probes and a Model 3100 monitoring system.

  20. Sequestration of maize crop straw C in different soils: role of oxyhydrates in chemical binding and stabilization as recalcitrance.

    Science.gov (United States)

    Song, Xiangyun; Li, Lianqing; Zheng, Jufeng; Pan, Genxing; Zhang, Xuhui; Zheng, Jinwei; Hussain, Qaiser; Han, Xiaojun; Yu, Xinyan

    2012-05-01

    While biophysical controls on the sequestration capacity of soils have been well addressed with physical protection, chemical binding and stabilization processes as well as microbial community changes, the role of chemical binding and stabilization has not yet well characterized for soil organic carbon (SOC) sequestration in rice paddies. In this study, a 6-month laboratory incubation with and without maize straw amendment (MSA) was conducted using topsoil samples from soils with different clay mineralogy and free oxy-hydrate contents collected across Southern China. The increase in SOC under MSA was found coincident with that in Fe- and Al-bound OC (Fe/Al-OC) after incubation for 30 d (R(2)=0.90, P=0.05), and with sodium dithionate-citrate-bicarbonate (DCB) extractable Fe after incubation for 180 d (R(2)=0.99, Psoils rich in DCB extractable Fe than those poor in DCB extractable Fe. The greater SOC sequestration in soils rich in DCB extractable Fe was further supported by the higher abundance of (13)C which was a natural signature of MSA. Moreover, a weak positive correlation of the increased SOC under MSA with the increased humin (R(2)=0.87, P=0.06) observed after incubation for 180 d may indicate a chemical stabilization of sequestered SOC as humin in the long run. These results improved our understanding of SOC sequestration in China's rice paddies that involves an initial chemical binding of amended C and a final stabilization as recalcitrant C of humin. Copyright © 2012 Elsevier Ltd. All rights reserved.

  1. Partially stabilized zirconia (PSZ) - what's in it for chemical engineers?

    International Nuclear Information System (INIS)

    Michelmore, A.G.

    1988-01-01

    Partial Stabilized Zirconia (PSZ) is a non-brittle ceramic material with virtually the same modulus of elasticity, Poisson's ratio, tensile strength, and co-efficient of thermal expansion as steel, coupled with low thermal conductivity, low electrical conductivity, high hardness, non-magnetic properties and high corrosion resistance. Uses are in a wide variety of applications such as automotive, computer, hot copper extrusion dies, delicate laboratory equipment, mining spigots and injection moulding gates for plastic. Applications previously thought to be impossible for ceramics such as in high thermal and/or mechanical shock situations are now possible with benefits such as longer life, reduced maintenance costs, less downtime, lower stock inventory and improved productivity. Examples given here include downhole pump check valves in the oil and gas industry, dry bearings in the mining industry and plungers for pumping tomato paste in the food processing industry. A brief comparison is made of other PSZs and Nilcra PSZ. 1 fig

  2. Further observations on sensitization of chemically stabilized stainless steels

    International Nuclear Information System (INIS)

    Samans, C.H.; Kinoshita, K.; Matsushima, I.

    1977-01-01

    Niobium additions to an 18Cr:8Ni type matrix reduce carbon solubility to such an extent that any ''solution treatment'' below 1150 0 C causes stabilization. Consequently, no Cr 23 C 6 precipitates at lower temperatures to sensitize the structure. Further observations on Type 321 suggest that two types of TiC precipitate from solid solution in an 18 : 8 type matrix. The size of the TiC nucleus decreases with the precipitating temperature. Above 1050 to 1100 0 C the initial TiC is probably incoherent, large enough to be stable, and resistant to ferric sulfate-sulfuric acid solution. Below 1050 to 1100 0 C the initial TiC, known as ''dot TiC'' or ''TiC on dislocations,'' is probably coherent, not large enough to be stable without further growth, and not resistant to ferric sulfate-sulfuric acid solution. During holding at temperatures below 1050 to 1100 0 C, stabilization occurs as the TiC on dislocations agglomerates to larger, incoherent particles. The time required increases as the temperature decreases down to the minimum TiC nucleation temperature near 610 0 C. Cold work makes it easier for the coherent particles to become incoherent, in effect facilitating approach to equilibrium carbon solubility at any temperature. Once chromium carbide forms, dissolved titanium eventually reacts with it, forming TiC and releasing chromium to desensitize the structure. This reaction can occur, given sufficient time for titanium diffusion, at any temperature at which chromium carbide nucleates. It is much more rapid than back diffusion of chromium from the matrix

  3. Repeated chemical immobilization of a captive greater one-horned rhinoceros (Rhinoceros unicornis), using combinations of etorphine, detomidine, and ketamine.

    Science.gov (United States)

    Atkinson, Mark W; Hull, Bruce; Gandolf, A Rae; Blumer, Evan S

    2002-06-01

    An adult, 23 yr-old, male greater one-horned rhinoceros (Rhinoceros unicornis) was repeatedly immobilized with combinations of etorphine, detomidine, and ketamine to provide medical and surgical care to chronic, bilateral, soft tissue lesions on the hind feet and to collect semen by electroejaculation. The rhinoceros was successfully immobilized on 24 occasions over a 55 mo period at approximately 8-10 wk intervals, 17 times with a combination of etorphine and detomidine (M99-D, i.m.) by projectile dart and seven times with a combination of etorphine, ketamine, and detomidine (M99-K-D, i.m.) by pole syringe. The combination of etorphine, detomidine, and ketamine repeatedly and safely induced prolonged anesthesia, and a suitable drug combination includes 3.5-3.8 mg etorphine, 14 mg detomidine, and 400 mg ketamine (M99-K-D) administered i.m. into the neck.

  4. A New Pseudoinverse Matrix Method For Balancing Chemical Equations And Their Stability

    International Nuclear Information System (INIS)

    Risteski, Ice B.

    2008-01-01

    In this work is given a new pseudoniverse matrix method for balancing chemical equations. Here offered method is founded on virtue of the solution of a Diophantine matrix equation by using of a Moore-Penrose pseudoinverse matrix. The method has been tested on several typical chemical equations and found to be very successful for the all equations in our extensive balancing research. This method, which works successfully without any limitations, also has the capability to determine the feasibility of a new chemical reaction, and if it is feasible, then it will balance the equation. Chemical equations treated here possess atoms with fractional oxidation numbers. Also, in the present work are introduced necessary and sufficient criteria for stability of chemical equations over stability of their extended matrices

  5. Chemical stability of insulin. 3. Influence of excipients, formulation, and pH.

    Science.gov (United States)

    Brange, J; Langkjaer, L

    1992-01-01

    The influence of auxiliary substances and pH on the chemical transformations of insulin in pharmaceutical formulation, including various hydrolytic and intermolecular cross-linking reactions, was studied. Bacteriostatic agents had a profound stabilizing effect--phenol > m-cresol > methylparaben--on deamidation as well as on insulin intermolecular cross-linking reactions. Of the isotonicity substances, NaCl generally had a stabilizing effect whereas glycerol and glucose led to increased chemical deterioration. Phenol and sodium chloride exerted their stabilizing effect through independent mechanisms. Zinc ions, in concentrations that promote association of insulin into hexamers, increase the stability, whereas higher zinc content had no further influence. Protamine gave rise to additional formation of covalent protamine-insulin products which increased with increasing protamine concentration. The impact of excipients on the chemical processes seems to be dictated mainly via an influence on the three-dimensional insulin structure. The effect of the physical state of the insulin on the chemical stability was also complex, suggesting an intricate dependence of intermolecular proximity of involved functional groups. At pH values below five and above eight, insulin degrades relatively fast. At acid pH, deamidation at residue A21 and covalent insulin dimerization dominates, whereas disulfide reactions leading to covalent polymerization and formation of A- and B-chains prevailed in alkaline medium. Structure-reactivity relationship is proposed to be a main determinant for the chemical transformation of insulin.

  6. Importance of asparagine on the conformational stability and chemical reactivity of selected anti-inflammatory peptides

    Energy Technology Data Exchange (ETDEWEB)

    Soriano-Correa, Catalina, E-mail: csorico@comunidad.unam.mx [Química Computacional, Facultad de Estudios Superiores (FES)-Zaragoza, Universidad Nacional Autónoma de México (UNAM), Iztapalapa, C.P. 09230 México, D.F. (Mexico); Barrientos-Salcedo, Carolina [Laboratorio de Química Médica y Quimiogenómica, Facultad de Bioanálisis Campus Veracruz-Boca del Río, Universidad Veracruzana, C.P. 91700 Veracruz (Mexico); Campos-Fernández, Linda; Alvarado-Salazar, Andres [Química Computacional, Facultad de Estudios Superiores (FES)-Zaragoza, Universidad Nacional Autónoma de México (UNAM), Iztapalapa, C.P. 09230 México, D.F. (Mexico); Esquivel, Rodolfo O. [Departamento de Química, Universidad Autónoma Metropolitana-Iztapalapa (UAM-Iztapalapa), C.P. 09340 México, D.F. (Mexico)

    2015-08-18

    Highlights: • Asparagine plays an important role to anti-inflammatory effect of peptides. • The electron-donor substituent groups favor the formation of the hydrogen bonds, which contribute in the structural stability of peptides. • Chemical reactivity and the physicochemical features are crucial in the biological functions of peptides. - Abstract: Inflammatory response events are initiated by a complex series of molecular reactions that generate chemical intermediaries. The structure and properties of peptides and proteins are determined by the charge distribution of their side chains, which play an essential role in its electronic structure and physicochemical properties, hence on its biological functionality. The aim of this study was to analyze the effect of changing one central amino acid, such as substituting asparagine for aspartic acid, from Cys–Asn–Ser in aqueous solution, by assessing the conformational stability, physicochemical properties, chemical reactivity and their relationship with anti-inflammatory activity; employing quantum-chemical descriptors at the M06-2X/6-311+G(d,p) level. Our results suggest that asparagine plays a more critical role than aspartic acid in the structural stability, physicochemical features, and chemical reactivity of these tripeptides. Substituent groups in the side chain cause significant changes on the conformational stability and chemical reactivity, and consequently on their anti-inflammatory activity.

  7. Hypothesis for prediction of environmental stability of chemicals by mass spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Tremolada, P; Di Guardo, A; Calamari, D; Davoli, E; Fanelli, R [Milan Univ. (Italy). Ist. di Entomologia Agraria Istituto di Ricerche Farmacologiche Mario Negri, Milan (Italy)

    1992-01-01

    The environmental persistence of organic chemicals is generally very hard to predict. In this work, the hypothesis of the use of fragmentation data in Mass Spectrometry (MS) as a possible 'stability index' of the molecules is presented. Since the fragmentation is determined by the thermodynamic properties of the molecules, it is possible to deduct information about the 'intrinsic stability' of a chemical. Such information can be used and correlated to predict the environmental degradability of a substance, especially referring to abiotic degradation. To study this relation, three different methods of measuring the fragmentation patterns are compared. All the methods show similar behaviour and one of them, in particular, shows a very good qualitative correlation between fragmentation data and persistence values found in literature. A possible 'stability index' for the quantitative prediction of the environmental degradation of a chemical is discussed.

  8. Characterisation of chemical composition and energy content of green waste and municipal solid waste from Greater Brisbane, Australia.

    Science.gov (United States)

    Hla, San Shwe; Roberts, Daniel

    2015-07-01

    The development and deployment of thermochemical waste-to-energy systems requires an understanding of the fundamental characteristics of waste streams. Despite Australia's growing interest in gasification of waste streams, no data are available on their thermochemical properties. This work presents, for the first time, a characterisation of green waste and municipal solid waste in terms of chemistry and energy content. The study took place in Brisbane, the capital city of Queensland. The municipal solid waste was hand-sorted and classified into ten groups, including non-combustibles. The chemical properties of the combustible portion of municipal solid waste were measured directly and compared with calculations made based on their weight ratios in the overall municipal solid waste. The results obtained from both methods were in good agreement. The moisture content of green waste ranged from 29% to 46%. This variability - and the tendency for soil material to contaminate the samples - was the main contributor to the variation of samples' energy content, which ranged between 7.8 and 10.7MJ/kg. The total moisture content of food wastes and garden wastes was as high as 70% and 60%, respectively, while the total moisture content of non-packaging plastics was as low as 2.2%. The overall energy content (lower heating value on a wet basis, LHVwb) of the municipal solid waste was 7.9MJ/kg, which is well above the World Bank-recommended value for utilisation in thermochemical conversion processes. Copyright © 2015 Elsevier Ltd. All rights reserved.

  9. Stability of racemic and chiral steady states in open and closed chemical systems

    Energy Technology Data Exchange (ETDEWEB)

    Ribo, Josep M. [Departament de Quimica Organica, Universitat de Barcelona, c. Marti i Franques 1, Barcelona (Spain); Hochberg, David [Centro de Astrobiologia (CSIC-INTA), Ctra. Ajalvir Km. 4, 28850 Torrejon de Ardoz, Madrid (Spain)], E-mail: hochbergd@inta.es

    2008-12-22

    The stability properties of models of spontaneous mirror symmetry breaking in chemistry are characterized algebraically. The models considered here all derive either from the Frank model or from autocatalysis with limited enantioselectivity. Emphasis is given to identifying the critical parameter controlling the chiral symmetry breaking transition from racemic to chiral steady-state solutions. This parameter is identified in each case, and the constraints on the chemical rate constants determined from dynamic stability are derived.

  10. Stability of racemic and chiral steady states in open and closed chemical systems

    International Nuclear Information System (INIS)

    Ribo, Josep M.; Hochberg, David

    2008-01-01

    The stability properties of models of spontaneous mirror symmetry breaking in chemistry are characterized algebraically. The models considered here all derive either from the Frank model or from autocatalysis with limited enantioselectivity. Emphasis is given to identifying the critical parameter controlling the chiral symmetry breaking transition from racemic to chiral steady-state solutions. This parameter is identified in each case, and the constraints on the chemical rate constants determined from dynamic stability are derived

  11. Using proven, cost-effective chemical stabilization to remediate radioactive and heavy metal contaminated sites

    International Nuclear Information System (INIS)

    Jensen, R.; Sogue, A.

    1999-01-01

    Rocky Mountain Remediation Services, L.L.C. (RMRS) has deployed a cost-effective metals stabilization method which can be used to reduce the cost of remediation projects where radioactivity and heavy metals are the contaminants of concern. The Envirobond TM process employs the use of a proprietary chemical process to stabilize metals in many waste forms, and provides an excellent binding system that can easily be compacted to reduce the waste into a shippable brick called Envirobric TM . The advantages of using chemical stabilization are: (1) Low cost, due to the simplicity of the process design and inexpensive reagents. (2) Chemical stabilization is easily deployed in field applications, which limit the amount of shielding and other protective measures. (3) The process does not add volume and bulk to the treated waste; after treatment the materials may be able to remain on-site, or if transportation and disposal is required the cost will be reduced due to lower volumes. (4) No secondary waste. The simplicity of this process creates a safe environment while treating the residues, and the long-term effectiveness of this type of chemical stabilization lowers the risk of future release of hazardous elements associated with the residues. (author)

  12. Thermodynamic stability of elementary chemical reactions proceeding at finite rates revisited using Lyapunov function analysis

    International Nuclear Information System (INIS)

    Burande, Chandrakant S.; Bhalekar, Anil A.

    2005-01-01

    The thermodynamic stability of a few representative elementary chemical reactions proceeding at finite rates has been investigated using the recently proposed thermodynamic Lyapunov function and following the steps of Lyapunov's second method (also termed as the direct method) of stability of motion. The thermodynamic Lyapunov function; L s , used herein is the excess rate of entropy production in the thermodynamic perturbation space, which thereby inherits the dictates of the second law of thermodynamics. This Lyapunov function is not the same as the excess entropy rate that one encounters in thermodynamic (irreversible) literature. The model chemical conversions studied in this presentation are A+B→v x X and A+B↔ν x X. For the sake of simplicity, the thermal effects of chemical reactions have been considered as not adding to the perturbation as our main aim was to demonstrate how one should use systematically the proposed thermodynamic Lyapunov function following the steps of Lyapunov's second method of stability of motion. The domains of thermodynamic stability under the constantly acting small disturbances, thermodynamic asymptotic stability and thermodynamic instability in these model systems get established

  13. New class of thermosetting plastics has improved strength, thermal and chemical stability

    Science.gov (United States)

    Burns, E. A.; Dubrow, B.; Lubowitz, H. R.

    1967-01-01

    New class of thermosetting plastics has high hydrocarbon content, high stiffness, thermal stability, humidity resistance, and workability in the precured state. It is designated cyclized polydiene urethane, and is applicable as matrices to prepare chemically stable ablative materials for rocket nose cones of nozzles.

  14. Design and construction control guidance for chemically stabilized pavement base layers.

    Science.gov (United States)

    2013-12-01

    A laboratory and field study was conducted related to chemically stabilized pavement layers, which is also : referred to as soil-cement. Soil-cement practices within MDOT related to Class 9C soils used for base layers : were evaluated in this report....

  15. Leaching behavior and chemical stability of copper butyl xanthate complex under acidic conditions.

    Science.gov (United States)

    Chang, Yi Kuo; Chang, Juu En; Chiang, Li Choung

    2003-08-01

    Although xanthate addition can be used for treating copper-containing wastewater, a better understanding of the leaching toxicity and the stability characteristics of the copper xanthate complexes formed is essential. This work was undertaken to evaluate the leaching behavior of copper xanthate complex precipitates by means of toxicity characteristics leaching procedure (TCLP) and semi-dynamic leaching test (SDLT) using 1 N acetic acid solution as the leachant. Also, the chemical stability of the copper xanthate complex during extraction has been examined with the studying of variation of chemical structure using UV-vis, Fourier transform infrared and X-ray photoelectron spectroscopies (XPS). Both TCLP and SDLT results showed that a negligible amount of copper ion was leached out from the copper xanthate complex precipitate, indicating that the complex exhibited a high degree of copper leaching stability under acidic conditions. Nevertheless, chemical structure of the copper xanthate complex precipitate varied during the leaching tests. XPS data suggested that the copper xanthate complex initially contained both cupric and cuprous xanthate, but the unstable cupric xanthate change to the cuprous form after acid extraction, indicating the cuprous xanthate to be the final stabilizing structure. Despite that, the changes of chemical structure did not induce the rapid leaching of copper from the copper xanthate complex.

  16. Evaluation of the effects of enzyme-based liquid chemical stabilizers on subgrade soils

    CSIR Research Space (South Africa)

    Mgangira, Martin B

    2009-07-01

    Full Text Available The purpose of this study was to asses the strength of enzyme treated soil material. Thus the aim of the paper is to present laboratory results on the effects of two enzyme-based liquid chemicals as soil stabilizers. Soil samples were prepared...

  17. Efficient first-principles prediction of solid stability: Towards chemical accuracy

    Science.gov (United States)

    Zhang, Yubo; Kitchaev, Daniil A.; Yang, Julia; Chen, Tina; Dacek, Stephen T.; Sarmiento-Pérez, Rafael A.; Marques, Maguel A. L.; Peng, Haowei; Ceder, Gerbrand; Perdew, John P.; Sun, Jianwei

    2018-03-01

    The question of material stability is of fundamental importance to any analysis of system properties in condensed matter physics and materials science. The ability to evaluate chemical stability, i.e., whether a stoichiometry will persist in some chemical environment, and structure selection, i.e. what crystal structure a stoichiometry will adopt, is critical to the prediction of materials synthesis, reactivity and properties. Here, we demonstrate that density functional theory, with the recently developed strongly constrained and appropriately normed (SCAN) functional, has advanced to a point where both facets of the stability problem can be reliably and efficiently predicted for main group compounds, while transition metal compounds are improved but remain a challenge. SCAN therefore offers a robust model for a significant portion of the periodic table, presenting an opportunity for the development of novel materials and the study of fine phase transformations even in largely unexplored systems with little to no experimental data.

  18. Vastly enhancing the chemical stability of phosphorene by employing an electric field.

    Science.gov (United States)

    Gao, Junfeng; Zhang, Gang; Zhang, Yong-Wei

    2017-03-23

    Currently, a major hurdle preventing phosphorene from various electronic applications is its rapid oxidation under ambient conditions. Thus how to enhance its chemical stability by suppressing oxidation becomes an urgent task. Here, we reveal a highly effective procedure to suppress the oxidation of phosphorene by employing a suitable van der Waals (vdW) substrate and a vertical electric field. Our first-principles study shows that the phosphorene-MoSe 2 vdW heterostructure is able to reverse the stability of physisorption and chemisorption of molecular O 2 on phosphorene. With further application of a vertical electric field of -0.6 V Å -1 , the energy barrier for oxidation is able to further increase to 0.91 eV, leading to a 10 5 times enhancement in its lifetime compared with that without using the procedure at room temperature. Our work presents a viable strategy to vastly enhance the chemical stability of phosphorene in air.

  19. Chemical and thermal stability of core-shelled magnetite nanoparticles and solid silica

    Science.gov (United States)

    Cendrowski, Krzysztof; Sikora, Pawel; Zielinska, Beata; Horszczaruk, Elzbieta; Mijowska, Ewa

    2017-06-01

    Pristine nanoparticles of magnetite were coated by solid silica shell forming core/shell structure. 20 nm thick silica coating significantly enhanced the chemical and thermal stability of the iron oxide. Chemical and thermal stability of this structure has been compared to the magnetite coated by mesoporous shell and pristine magnetite nanoparticles. It is assumed that six-membered silica rings in a solid silica shell limit the rate of oxygen diffusion during thermal treatment in air and prevent the access of HCl molecules to the core during chemical etching. Therefore, the core/shell structure with a solid shell requires a longer time to induce the oxidation of iron oxide to a higher oxidation state and, basically, even strong concentrated acid such as HCl is not able to dissolve it totally in one month. This leads to the desired performance of the material in potential applications such as catalysis and environmental protection.

  20. Evaluation of the influence of fluoroquinolone chemical structure on stability: forced degradation and in silico studies

    Directory of Open Access Journals (Sweden)

    André Valle de Bairros

    2018-05-01

    Full Text Available ABSTRACT Fluoroquinolones are a known antibacterial class commonly used around the world. These compounds present relative stability and they may show some adverse effects according their distinct chemical structures. The chemical hydrolysis of five fluoroquinolones was studied using alkaline and photolytic degradation aiming to observe the differences in molecular reactivity. DFT/B3LYP-6.31G* was used to assist with understanding the chemical structure degradation. Gemifloxacin underwent degradation in alkaline medium. Gemifloxacin and danofloxacin showed more degradation perceptual indices in comparison with ciprofloxacin, enrofloxacin and norfloxacin in photolytic conditions. Some structural features were observed which may influence degradation, such as the presence of five member rings attached to the quinolone ring and the electrostatic positive charges, showed in maps of potential electrostatic charges. These measurements may be used in the design of effective and more stable fluoroquinolones as well as the investigation of degradation products from stress stability assays.

  1. Physico-chemical, microbiological and sensory stability of chemically preserved mango pulp

    International Nuclear Information System (INIS)

    Akhtar, S.; Riaz, M.; Nisar, A.

    2010-01-01

    The effect of sodium benzoate (SB) and potassium metabisulphite (PMS) at various concentrations on chemical, microbiological and sensory quality of mango pulp during storage was assessed. Inhibitory activity of the chemical preservatives and their effect on chemical and sensory attributes was tested periodically by simulating the industrial mango pulp storage in the lab (30-42 deg. C in the dark), for a period of 90 days. Protein, fats, decreased while ash content and total soluble solid (TSS) increased during the storage period. A slight progressive decline in pH was observed with a proportional increase (p<0.05) in the acidity of the stored pulp samples. Significant inhibition of the total bacterial count (TBC) was observed on applying the specified concentrations, however PMS was shown to be more inhibitory. Storage time significantly (p<0.05) increased the CFU/g of the pulp samples as the maximum growth was observed after 90 days of storage. Sensory characteristics of the juice prepared from treated mango pulp samples were affected negatively on addition of preservatives however, the samples were accepted by the judges even after three months of storage. (author)

  2. Physical and chemical stability of palonosetron HCl in 4 infusion solutions.

    Science.gov (United States)

    Trissel, Lawrence A; Xu, Quanyun A

    2004-10-01

    Palonosetron HCl is a selective 5-HT(3) receptor antagonist used for the prevention of chemotherapy-induced nausea and vomiting. Palonosetron HCl may be diluted in an infusion solution for administraton. Consequently, stability information is needed for palonosetron HCl admixed in common infusion solutions. To evaluate the physical and chemical stability of palonosetron HCl in concentrations of 5 and 30 microg/mL in dextrose 5% injection, NaCl 0.9% injection, dextrose 5% in NaCl 0.45% injection, and dextrose 5% in lactated Ringer's injection. Triplicate test samples of palonosetron HCl at each concentration in each diluent were tested. Samples were stored and evaluated at appropriate intervals for up to 48 hours at room temperature ( approximately 23 degrees C) and 14 days under refrigeration (4 degrees C). Physical stability was assessed using turbidimetric and particulate measurement, as well as visual inspection. Chemical stability was assessed by HPLC. All of the admixtures were initially clear and colorless when viewed in normal fluorescent room light and with a Tyndall beam. Measured turbidity and particulate content were low initially and remained low throughout the study. The drug concentration was unchanged in any of the samples at either temperature throughout the study. Palonosetron HCl is physically and chemically stable in all 4 common infusion solutions for at least 48 hours at room temperature and 14 days under refrigeration.

  3. Application of isotope-labelled compounds in the study of the chemical stability of pesticides

    International Nuclear Information System (INIS)

    Roesseler, M.; Luther, D.; Abendroth, H.C.; Koch, H.

    1980-01-01

    The user of pesticides requires specific biological modes of action from the corresponding commercial products. Impurities and degradation products may cause uncontrollable toxicological reactions. Profound knowledge of the chemical stability of the effective substance in question and its formulations under storage conditions as well as under those of analytical sample preparation and detection is required. Radioisotope labelled effective substances dimethoate and 1-butyl-amino-cyclohexane-phosphonic acid dibutyl ester are used to study storage stability of the pure effective substance and its formulations; effects of selected impurities, such as technical by-products, moisture or water content, binding or carrier materials, organic solvents, chemical stabilizers and other formulation components on storage properties; temperature dependence of storage stability; selection of suitable analytical techniques for quantitative determination of the effective substance without interference effects from any by-product; reduction of the necessary analytical expense; disclosure of sources of error in the application of usual analytical techniques; improvement of possibilities of an immediate and clearer discrimination between types and amounts of compounds in a chemical system consisting of one pesticide and its degradation or reaction products at the beginning and at the end of an experimental or reaction period. Radiochemical analytical techniques, such as radio thin-layer chromatography (also combined with liquid scintillation counting), radio gas chromatography, autoradiography and isotope dilution analysis were used. Results are discussed, especially of experiments on dimethoate and its technical by-products

  4. Chemical derivation to enhance the chemical/oxidative stability of resorcinol-formaldehyde (R-F) resin

    International Nuclear Information System (INIS)

    Hubler, T.L.; Shaw, W.J.; Brown, G.N.; Linehan, J.C.; Franz, J.A.; Hart, T.R.; Hogan, M.O.

    1996-09-01

    Tank wastes at Hanford and SRS contain highly alkaline supernate solutions of conc. Na, K nitrates with large amounts of 137 Cs. It is desirable to remove and concentrate the highly radioactive fraction for vitrification. One candidate ion exchange material for removing the radiocesium is R-F resin. This report summarizes studies into synthesis and characterization of 4-derivatized R-F resins prepared in pursuit of more chemically/oxidatively robust resin. 85% 4-fluororesorcinol/15% phenol formaldehyde resin appears to have good stability in alkaline solution, although there may be some nucleophilic displacement reaction during synthesis; further studies are needed

  5. Thermal stability of Trichoderma reesei c30 cellulase and aspergillus niger; -glucosidase after ph and chemical modification

    Energy Technology Data Exchange (ETDEWEB)

    Woodward, J.; Whaley, K.S.; Zachry, G.S.; Wohlpart, D.L.

    1981-01-01

    Treatment of Trichoderma reesei C30 cellulase at pH 10.0 for 1 h at room temperature increased its pH and thermal stability. Chemical modification of the free epsilon-amino groups of cellulase at pH 10.0 resulted in no further increase in stability. Such chemical modification, however, decreased the thermal stability of the cellulose-cellulase complex. On the contrary, the chemical modification of Aspergillus niger glucosidase with glutaraldehyde at pH 8.0 increased the thermal stability of this enzyme.

  6. Thermal stability of Trichoderma reesei C30 cellulase and Aspergillus niger. beta. -glucosidase after pH and chemical modification

    Energy Technology Data Exchange (ETDEWEB)

    Woodward, J.; Whaley, K.S.; Zachry, G.S.; Wohlpart, D.L.

    1981-01-01

    Treatment of Trichoderma reesei C30 cellulase at pH 10.0 for 1 h at room temperature increased its pH and thermal stability. Chemical modification of the free epsilon-amino groups of cellulase at pH 10.0 resulted in no further increase in stability. Such chemical modification, however, decreased the thermal stability of the cellulose-cellulase complex. On the contrary, the chemical modification of Aspergillus niger ..beta..-glucosidase with glutaraldehyde at pH 8.0 increased the thermal stability of this enzyme.

  7. Chemical stability of fluorine-containing coatings of cold drying for radiation - protection technique articles

    International Nuclear Information System (INIS)

    Shigorina, I.I.; Zvyagintseva, N.V.; Egorov, B.N.

    1977-01-01

    The chemical stability of fluorolon coatings, which are not subjected to heat treatment or hot drying during application, has been studied. The test for layer life-time has been performed by submerging specimens in agressive medium. The time for one upper removable layer to fail under steady action of agressive liquid is found to be: > 12 months at 20 deg C, 6-9 months at 40 deg C; at 60 deg C the time of layer stability depends upon medium: 1 month for nitric, 2 months for acetic, 2-3 months for sulphuric and hydrochloric acid. The coatings are recommended for practical application in radiation-protective technique

  8. Real cause of detrimental carbonation in chemically stabilized layers and possible solutions

    CSIR Research Space (South Africa)

    Botha, PB

    2005-10-01

    Full Text Available to determine the other reaction that may take place in the material. KEYWORDS CARBONATION/ CHEMICAL REACTIONS/ WATER CURING/ NEW TESTING PROTOCOL 1 INTRODUCTION This paper deals with the problems related to the “curing” of the stabilized layers... than CO2 driven. In actually fact the so-called “detrimental carbonation” chemical reaction cannot even take place without free water being available. The water is normally supplied by the specified curing 2 technique to keep the layer moist...

  9. Characterization of milk proteins-lutein complexes and the impact on lutein chemical stability.

    Science.gov (United States)

    Yi, Jiang; Fan, Yuting; Yokoyama, Wallace; Zhang, Yuzhu; Zhao, Liqing

    2016-06-01

    In this study, the interaction of WPI (whey protein isolate) and SC (sodium caseinate) with hydrophobic lutein was investigated through UV-vis spectroscopy and circular dichroism (CD) as well as fluorescence. The effects on lutein's chemical stability were also examined. The decrease of turbidity of lutein suggested that lutein's aqueous solubility was improved after binding with milk proteins. CD analysis indicated lutein had little impact on the secondary structures of both proteins. Different preparation methods have significant impacts on the binding constant. Fluorescence results indicated that WPI and SC interact with lutein by hydrophobic contacts. Milk proteins have protective effects on lutein against oxidation and decomposition, and SC showed better capability in protecting lutein from oxidation than WPI during 16 days storage. The lutein's chemical stability was increased with increasing of proteins concentration. The results indicated that milk proteins may act as effective carriers for lipophilic nutraceuticals. Copyright © 2016 Elsevier Ltd. All rights reserved.

  10. Metal and anion composition of two biopolymeric chemical stabilizers and toxicity risk implication for the environment.

    Science.gov (United States)

    Ndibewu, P P; Mgangira, M B; Cingo, N; McCrindle, R I

    2010-01-01

    The objective of this study was to (1) measure the concentration of four anions (Cl(-), F(-), [image omitted], and [image omitted]) and nine other elements (Al, Ba, Ca, K, Mg, Mn, Fe, Ni, and Si) in two nontraditional biopolymeric chemical stabilizers (EBCS1 and EBCS2), (2) investigate consequent environmental toxicity risk implications, and (3) create awareness regarding environmental health issues associated with metal concentration levels in enzyme-based chemical stabilizers that are now gaining widespread application in road construction and other concrete materials. Potential ecotoxicity impacts were studied on aqueous extracts of EBCS1 and EBCS2 using two thermodynamic properties models: the Pitzer-Mayorga model (calculation of the electrolyte activity coefficients) and the Millero-Pitzer model (calculation of the ionic activity coefficients). Results showed not only high concentrations of a variety of metal ions and inorganic anions, but also a significant variation between two chemical stabilizing mixtures. The mixture (EBCS2) with the lower pH value was richer in all the cationic and anionic species than (EBCS1). Sulfate (SO(2-)(4)) concentrations were found to be higher in EBCS2 than in EBCS1. There was no correlation between electrolyte activity and presence of the ionic species, which may be linked to a possible high ionic environmental activity. The concentrations of trace metals found (Mn, Fe, and Ni) were low compared to those of earth metals (Ba, Ca, K, and Mg). The metal concentrations were higher in EBCS1 than in EBCS2. Data suggest that specific studies are needed to establish "zero" permissible metal ecotoxicity values for elements and anions in any such strong polyelectrolytic enzyme-based chemical stabilizers.

  11. A high throughput platform for understanding the influence of excipients on physical and chemical stability

    DEFF Research Database (Denmark)

    Raijada, Dhara; Cornett, Claus; Rantanen, Jukka

    2013-01-01

    The present study puts forward a miniaturized high-throughput platform to understand influence of excipient selection and processing on the stability of a given drug compound. Four model drugs (sodium naproxen, theophylline, amlodipine besylate and nitrofurantoin) and ten different excipients were...... for chemical degradation. The proposed high-throughput platform can be used during early drug development to simulate typical processing induced stress in a small scale and to understand possible phase transformation behaviour and influence of excipients on this....

  12. Chemical structure and radiation stability of solid crystalline antibiotics: thiamphenicol and chloramphenicol

    International Nuclear Information System (INIS)

    Varshney, Lalit; Soe Nwe

    1997-01-01

    Antibiotics in solid state show significant radiation resistance and some of them are exposed to gamma or electron beam irradiation for sterilization. Even small radiation degradation in solid state antibiotics is not desirable. Two antibiotics namely thiamphenicol (TPL) and chloramphenicol (CPL) having similar chemical and solid state structure were irradiated at different graded radiation doses to study their stability. Differential scanning calorimetry (DSC) was used to evaluate purity, entropy of radiation processing, heat of fusion and melting point. (author). 3 refs., 1 tab

  13. Enhancement of the chemical stability in confined δ-Bi2O3

    DEFF Research Database (Denmark)

    Sanna, Simone; Esposito, Vincenzo; Andreasen, Jens Wenzel

    2015-01-01

    Bismuth-oxide-based materials are the building blocks for modern ferroelectrics1, multiferroics2, gas sensors3, light photocatalysts4 and fuel cells5,6. Although the cubic fluorite δ-phase of bismuth oxide (δ-Bi2O3) exhibits the highest conductivity of known solid-state oxygen ion conductors5, its...... instability prevents use at low temperature7–10. Here we demonstrate the possibility of stabilizing δ-Bi2O3 using highly coherent interfaces of alternating layers of Er2O3-stabilized δ-Bi2O3 and Gd2O3-doped CeO2. Remarkably, an exceptionally high chemical stability in reducing conditions and redox cycles...

  14. On the stabilizing role of species diffusion in chemical enhanced oil recovery

    Science.gov (United States)

    Daripa, Prabir; Gin, Craig

    2015-11-01

    In this talk, the speaker will discuss a problem on the stability analysis related to the effect of species diffusion on stabilization of fingering in a Hele-Shaw model of chemical enhanced oil recovery. The formulation of the problem is motivated by a specific design principle of the immiscible interfaces in the hope that this will lead to significant stabilization of interfacial instabilities, there by improving oil recovery in the context of porous media flow. Testing the merits of this hypothesis poses some challenges which will be discussed along with some numerical results based on current formulation of this problem. Several open problems in this context will be discussed. This work is currently under progress. Supported by the grant NPRP 08-777-1-141 from the Qatar National Research Fund (a member of The Qatar Foundation).

  15. Thermal and chemical stabilities of some synthesized inorganic ion exchange materials

    International Nuclear Information System (INIS)

    EI-Naggar, I.M.; Abou-Mesalam, M.M.; El-Shorbagy, M.M.; Shady, S.A.

    2006-01-01

    Chromium and cerium titanate as inorganic ion exchange materials were synthesized by the reaction of potassium chromate or ammonium eerie nitrate with titanium tetrachloride with molar ratio equal unity. The crystal system of both chromium and cerium titanates were determined and set to be monoclinic and orthorhombic system's, respectively. The chemical composition of both chromium and cerium titanates was determined by X-ray fluorescence technique and based on the data obtained with other different techniques. A molecular formula for chromium and cerium titanates as Cr 2 Ti 12 O 27 . 13H 2 O and Ce 2 Ti 3 O 10 . 7.46H 2 O, respectively, was proposed. Thermal stabilities of both ion exchangers were investigated at different heating temperatures. Also the stability of chromium and cerium titanates for chemical attack was studied in different media. The data obtained showed high thermal and chemical stabilities of chromium and cerium titanate ion exchangers compared with the same group of ion exchange materials. The ion exchange capacities of chromium and cerium titanates at different heating temperature were also investigated

  16. Thermal and chemical stabilities of some synthesized inorganic ion exchange materials

    International Nuclear Information System (INIS)

    El-Naggar, I.M.; Abou-Mesalam, M. M.; El-Shorbagy, M.M.; Shady, S.A.

    2005-01-01

    Chromium and cerium titanate as inorganic ion exchange materials were synthesized by the reaction of potassium chromate or ammonium ceric nitrate with titanium tetrachloride with molar ratio equal unity. The crystal system of both chromium and cerium titanates were determined and set to be monoclinic and orthorhombic systems, respectively. The chemical composition of both chromium and cerium titanates were determined by X-ray fluorescence technique and based on the data obtained with other different techniques. We can proposed molecular formula for chromium and cerium titanates as Cr 2 Ti 1 2O27. 13H 2 O and Ce 2 ThO10. 7.46 H 2 O, respectively. Thermal stability of both ion exchangers was investigated at different heating temperatures. Also the stability of chromium and cerium titanates for chemical attack was studied in different media. The data obtained showed high thermal and chemical stabilities of chromium and cerium titanate ion exchangers compared to the same group of ion exchange materials. The ion exchange capacities of chromium and cerium titanates at different heating temperature were investigated

  17. Formulation design of oral pediatric Acetazolamide suspension: dose uniformity and physico-chemical stability study.

    Science.gov (United States)

    Santoveña, Ana; Suárez-González, Javier; Martín-Rodríguez, Cristina; Fariña, José B

    2017-03-01

    The formulation of an active pharmaceutical ingredient (API) as oral solution or suspension in pediatrics is a habitual practice, due to the non-existence of many commercialized medicines in pediatric doses. It is also the simplest way to prepare and administer them to this vulnerable population. The design of a formulation that assures the dose and the system stability depends on the physico-chemical properties of the API. In this study, we formulate a class IV API, Acetazolamide (AZM) as suspension for oral administration to pediatric population. The suspension must comply attributes of quality, safety and efficacy for this route of administration. We use simple compounding procedures, as well as fewer pure excipients, as recommended for children. Mass and uniformity content assays and physical and chemical stability studies were performed. To quantify the API an UPLC method was used. We verified the physico-chemical stability of the suspensions and that they passed the mass test of the European Pharmacopeia (EP), but not the dose uniformity test. This reveals that AZM must be formulated as liquid forms with a more complex system of excipients (not usually indicated in pediatrics), or otherwise solid forms capable of assuring uniformity of mass and dose for every dosage unit.

  18. The Effects of Lyophilization on the Physico-Chemical Stability of Sirolimus Liposomes

    Directory of Open Access Journals (Sweden)

    Parvin Zakeri-Milani

    2013-02-01

    Full Text Available Purpose: The major limitation in the widespread use of liposome drug delivery system is its instability. Lyophilization is a promising approach to ensure the long-term stability of liposomes. The aim of this study was to prepare sirolimus-loaded liposomes, study their stability and investigate the effect of lyophilization either in the presence or in the absence of lyoprotectant on liposome properties. Methods: Two types of multi-lamellar liposomes, conventional and fusogenic, containing sirolimus were prepared by modified thin film hydration method with different ratio of dipalmitoylphosphatidylcholine (DPPC, cholesterol and dioleoylphosphoethanolamine (DOPE, and were lyophilized with or without dextrose as lyoprotectant. Chemical stability investigation was performed at 4°C and 25°C until 6 months using a validated HPLC method. Physical stability was studied with determination of particle size (PS and encapsulation efficiency (EE % of formulations through 6 months. Results: Chemical stability test at 4°C and 25°C until 6 months showed that drug content of liposomes decreased 8.4% and 20.2% respectively. Initial mean EE % and PS were 72.8 % and 582 nm respectively. After 6 months mean EE % for suspended form, lyophilized without lyoprotectant and lyophilized with lyoprotectant were 54.8 %, 62.3% and 67.1 % at 4°C and 48.2%, 60.4 % and 66.8 % at 25°C respectively. Corresponding data for mean PS were 8229 nm, 2397 nm and 688nm at 4°C and 9362 nm, 1944 nm and 737 nm at 25°C respectively. Conclusion: It is concluded that lyophilization with and without dextrose could increase shelf life of liposome and dextrose has lyoprotectant effect that stabilized liposomes in the lyophilization process.

  19. Physical and chemical stability of proflavine contrast agent solutions for early detection of oral cancer.

    Science.gov (United States)

    Kawedia, Jitesh D; Zhang, Yan-Ping; Myers, Alan L; Richards-Kortum, Rebecca R; Kramer, Mark A; Gillenwater, Ann M; Culotta, Kirk S

    2016-02-01

    Proflavine hemisulfate solution is a fluorescence contrast agent to visualize cell nuclei using high-resolution optical imaging devices such as the high-resolution microendoscope. These devices provide real-time imaging to distinguish between normal versus neoplastic tissue. These images could be helpful for early screening of oral cancer and its precursors and to determine accurate margins of malignant tissue for ablative surgery. Extemporaneous preparation of proflavine solution for these diagnostic procedures requires preparation in batches and long-term storage to improve compounding efficiency in the pharmacy. However, there is a paucity of long-term stability data for proflavine contrast solutions. The physical and chemical stability of 0.01% (10 mg/100 ml) proflavine hemisulfate solutions prepared in sterile water was determined following storage at refrigeration (4-8℃) and room temperature (23℃). Concentrations of proflavine were measured at predetermined time points up to 12 months using a validated stability-indicating high-performance liquid chromatography method. Proflavine solutions stored under refrigeration were physically and chemically stable for at least 12 months with concentrations ranging from 95% to 105% compared to initial concentration. However, in solutions stored at room temperature increased turbidity and particulates were observed in some of the tested vials at 9 months and 12 months with peak particle count reaching 17-fold increase compared to baseline. Solutions stored at room temperature were chemically stable up to six months (94-105%). Proflavine solutions at concentration of 0.01% were chemically and physically stable for at least 12 months under refrigeration. The solution was chemically stable for six months when stored at room temperature. We recommend long-term storage of proflavine solutions under refrigeration prior to diagnostic procedure. © The Author(s) 2014.

  20. Chemical stability of insulin. 4. Mechanisms and kinetics of chemical transformations in pharmaceutical formulation.

    Science.gov (United States)

    Brange, J

    1992-01-01

    Insulin decomposes by a multitude of chemical reactions [1-3]. It deamidates at two different residues by entirely different mechanisms. In acid, deamidation at AsnA21 is intramolecularly catalyzed by the protonated C-terminal, whereas above pH 6 an intermediate imide formation at residue AsnB3 leads to isoAsp and Asp derivatives. The imide formation requires a large rotation around the alpha-carbon/peptide carbonyl carbon bond at B3, corresponding to a 10 A movement of the B-chain N-terminal. The main determinant for the rate of B3 deamidation, as well as for the ratio between the two products formed, is the local conformational structure, which is highly influenced by various excipients and the physical state of the insulin. An amazing thermolysin-like, autoproteolytic cleavage of the A-chain takes place in rhombohedral insulin crystals, mediated by a concerted catalytic action by several, inter-hexameric functional groups and Zn2+. Intermolecular, covalent cross-linking of insulin molecules occurs via several mechanisms. The most prominent type of mechanism is aminolysis by the N-terminals, leading to isopeptide linkages with the A-chain side-chain amides of residues GlnA15, AsnA18 and AsnA21. The same type of reaction also leads to covalent cross-linking of the N-terminal in protamine with insulin. Disulfide exchange reactions, initiated by lysis of the A7-B7 disulfide bridge, lead mainly to formation of covalent oligo- and polymers. Activation energy (Ea) for the neutral deamidation and the aminolysis reactions was found to be 80 and 119 KJ/mol, respectively.

  1. Processing and stabilization of Aloe Vera leaf gel by adding chemical and natural preservatives

    Directory of Open Access Journals (Sweden)

    N. Nazemi

    2017-11-01

    Full Text Available Background and objectives: Aloe vera has been used as a medicinal herb for thousands of years. Aloe vera leaves can be separated into latex and gel which have biological effects. Aloe gel is a potent source of polysaccharides. When the gel is exposed to air, it quickly decomposes and decays and loses most of its biological activity. There are various processing techniques for sterilizing and stabilizing the gel. The aim of this study was to improve stabilization of the gel by adding some chemical and natural preservatives. Methods: The gel was obtained from Aloe vera leaves and after some processing chemical and natural preservatives were added. Chemicals included citric acid, ascorbic acid, vitamin E and potassium sorbate while natural preservatives were two essential oils derived from Cinnamomum zeylanicum and Eugenia caryophyllata. All these operations were performed under sterile conditions and they were evaluated at different temperatures and times. Appearance and taste changes of gel were studied organoleptic. Microbiological tests and some physical assays such as pH, refractometry and viscosity properties as well as determination of total sugars were measured. NMR and FT-IR analyses were performed for determining the quality of samples. Results: After data analyzing, the results showed that the samples formulated with chemical additives together with essential oils were more suitable and stable compared to the control samples after 90 days and the effective ingredient acemannan, remained stable. Conclusion: The stable gel can be considered for therapeutic properties and be used for edible and medicinal purposes.

  2. Rapid continuous chemical methods for studies of nuclei far from stability

    CERN Document Server

    Trautmann, N; Eriksen, D; Gaggeler, H; Greulich, N; Hickmann, U; Kaffrell, N; Skarnemark, G; Stender, E; Zendel, M

    1981-01-01

    Fast continuous separation methods accomplished by combining a gas-jet recoil-transport system with a variety of chemical systems are described. Procedures for the isolation of individual elements from fission product mixtures with the multistage solvent extraction facility SISAK are presented. Thermochromatography in connection with a gas-jet has been studied as a technique for on-line separation of volatile fission halides. Based on chemical reactions in a gas-jet system itself separation procedures for tellurium, selenium and germanium from fission products have been worked out. All the continuous chemical methods can be performed within a few seconds. The application of such procedures to the investigation of nuclides far from the line of beta -stability is illustrated by a few examples. (16 refs).

  3. The physical and chemical stability of suspensions of sustained-release diclofenac microspheres.

    Science.gov (United States)

    Lewis, L; Boni, R L; Adeyeye, C M

    1998-01-01

    The major challenge in liquid sustained-release oral suspensions is to minimize drug diffusion into the suspending medium and to retain the original properties of the microparticles during storage. Diclofenac wax microspheres prepared by the hydrophobic congealable disperse phase method were formulated as a sustained release suspension and stored at three different temperatures (25, 37 and 45 degrees C) for 3 months, to evaluate the physical and chemical stability of the suspended microspheres. Suspensions of microspheres stored at ambient temperatures were both physically and chemically stable, but at higher temperatures, up to 45 degrees C, there was a decrease in drug release due to scaling and melting on the microsphere surface as observed by scanning electron microscopy. However, on prolonged storage, up to 90 days, especially at 45 degrees C, temperature became a dominant factor causing an increase in drug release. The suspension of diclofenac microspheres was chemically stable for 3 months, while the plain drug suspension exhibited slight degradation.

  4. Chemical properties and oxidative stability of Arjan (Amygdalus reuteri) kernel oil as emerging edible oil.

    Science.gov (United States)

    Tavakoli, Javad; Emadi, Teymour; Hashemi, Seyed Mohammad Bagher; Mousavi Khaneghah, Amin; Munekata, Paulo Eduardo Sichetti; Lorenzo, Jose Manuel; Brnčić, Mladen; Barba, Francisco J

    2018-05-01

    The oxidative stability, as well as the chemical composition of Amygdalus reuteri kernel oil (ARKO), were evaluated and compared to those of Amygdalus scoparia kernel oil (ASKO) and extra virgin olive oil (EVOO) during and after holding in the oven (170 °C for 8 h). The oxidative stability analysis was carried out by measuring the changes in conjugated dienes, carbonyl and acid values as well as oil/oxidative stability index and their correlation with the antioxidant compounds (tocopherol, polyphenols, and sterol compounds). The oleic acid was determined as the predominant fatty acid of ARKO (65.5%). Calculated oxidizability value and an iodine value of ARKO, ASKO and EVOO were reported as 3.29 and 3.24, 2.00 and 100.0, 101.4 and 81.9, respectively. Due to the high wax content (4.5% and 3.3%, respectively), the saponification number of ARKO and ASKO (96.4 and 99.8, respectively) was lower than that of EVOO (169.7). ARKO had the highest oxidative stability, followed by ASKO and EVOO. Therefore, ARKO can be introduced as a new source of edible oil with high oxidative stability. Copyright © 2018. Published by Elsevier Ltd.

  5. Idaho Chemical Processing Plant low-level waste grout stabilization development program FY-96 status report

    International Nuclear Information System (INIS)

    Herbst, A.K.

    1996-09-01

    The general purpose of the Grout Stabilization Development Program is to solidify and stabilize the liquid low-level wastes (LLW) generated at the Idaho Chemical Processing Plant (ICPP). It is anticipated that LLW will be produced from the following: (1) chemical separation of the tank farm high-activity sodium-bearing waste; (2) retrieval, dissolution, and chemical separation of the aluminum, zirconium, and sodium calcines; (3) facility decontamination processes; and (4) process equipment waste. The main tasks completed this fiscal year as part of the program were chromium stabilization study for sodium-bearing waste and stabilization and solidification of LLW from aluminum and zirconium calcines. The projected LLW will be highly acidic and contain high amounts of nitrates. Both of these are detrimental to Portland cement chemistry; thus, methods to precondition the LLW and to cure the grout were explored. A thermal calcination process, called denitration, was developed to solidify the waste and destroy the nitrates. A three-way blend of Portland cement, blast furnace slag, and fly ash was successfully tested. Grout cubes were prepared at various waste loadings to maximize loading while meeting compressive strength and leach resistance requirements. For the sodium LLW, a 25% waste loading achieves a volume reduction of 3.5 and a compressive strength of 2,500 pounds per square inch while meeting leach, mix, and flow requirements. It was found that the sulfur in the slag reduces the chromium leach rate below regulatory limits. For the aluminum LLW, a 15% waste loading achieves a volume reduction of 8.5 and a compressive strength of 4,350 pounds per square inch while meeting leach requirements. Likewise for zirconium LLW, a 30% waste loading achieves a volume reduction of 8.3 and a compressive strength of 3,570 pounds per square inch

  6. Evaluation of chemical stabilizers and windscreens for wind erosion control of uranium mill tailings

    International Nuclear Information System (INIS)

    Elmore, M.R.; Hartley, J.N.

    1984-08-01

    Potential wind erosion of uranium mill tailings is a concern for the surface disposal of tailings at uranium mills. Wind-blown tailings may subsequently be redeposited on areas outside the impoundment. Pacific Northwest Laboratory (PNL) is investigating techniques for fugitive dust control at uranium mill tailings piles. Laboratory tests, including wind tunnel studies, were conducted to evaluate the relative effectiveness of 43 chemical stabilizers. Seventeen of the more promising stabilizers were applied to test plots on a uranium tailings pile at the American Nuclear Corporation-Gas Hills Project mill site in central Wyoming. The durabilities of these materials under actual site conditions were evaluated over time. In addition, field testing of commercially available windscreens was conducted. Test panels were constructed of eight different materials at the Wyoming test site to compare their durability. A second test site was established near PNL to evaluate the effectiveness of windscreens at reducing wind velocity, and thereby reduce the potential for wind erosion of mill tailings. Results of the laboratory land field tests of the chemical stabilizers and windscreens are presented, along with costs versus effectiveness of these techniques for control of wind erosion at mill tailings piles. 12 references, 4 figures, 6 tables

  7. Study on thermal stability and chemical structure of polyamide blended with small amount of Cu

    International Nuclear Information System (INIS)

    Arai, Tsuyoshi; Ueno, Tomonaga; Kajiya, Takafumi; Ishikawa, Tomoyuki; Takeda, Kunihiko

    2007-01-01

    The thermal stability and the chemical structure of Polyamide 66 (PA66) blended with a small amount of copper have been studied. The thermal degradation of the blend with 35 ppm or more of copper was restrained and no strong influence of the concentration of copper was observed. The molecular weight of PA66 decreased by the thermal aging process but the amount of decrease of the blend was smaller than that of the non-blend. The water uptake of the blend increased. The chemical structure, which was observed by IR and NMR, changed slightly by blending with copper after aging at higher temperatures. Multiple items influenced the thermal stability of PA66 blended with a small amount of copper instead of just one. Namely, the main chain of PA66 is cut by heat and the degree of the cut is restrained by the copper. The diffusion time of copper atoms that disperse uniformly in the PA66 matrix is short enough to cover the individual amide groups and the effect enlarges the entire configuration of the PA66 chain to enhance the thermal stability. (author)

  8. Deposition of yttria stabilized zirconia layer for solid oxide fuel cell by chemical vapor infiltration

    International Nuclear Information System (INIS)

    John, John T.; Dubey, Vivekanand; Kain, Vivekanand; Dey, Gautham Kumar; Prakash, Deep

    2011-01-01

    Free energy associated with a chemical reaction can be converted into electricity, if we can split the reaction into an anodic reaction and a cathodic reaction and carry out the reactions in an electrochemical cell using electrodes that will catalyze the reactions. We also have to use a suitable electrolyte, that serves to isolate the chemical species in the two compartments from getting mixed directly but allow an ion produced in one of the reactions to proceed to the other side and complete the reaction. For this reason cracks and porosity are not tolerated in the electrolyte. First generation solid oxide fuel cell (SOFC) uses yttria stabilized zirconia (YSZ) as the electrolyte. In spite of the fact that several solid electrolytes with higher conductivities at lower temperature are being investigated and developed, 8 mol% yttria stabilized zirconia (8YSZ) is considered to be the most favored electrolyte for the SOFC today. The electrolyte should be present as a thin, impervious layer of uniform thickness with good adherence, chemical and mechanical stability, in between the porous cathode and anode. Efforts to produce the 8YSZ coatings on porous lanthanum strontium manganite tubes by electrochemical vapor deposition (ECVD) have met with unexpected difficulties such as impurity pick up and chemical and mechanical instability of the LSM tubes in the ECVD environment. It was also difficult to keep the chemical composition of the YSZ coating at exactly 8 mol% Yttria in zirconia and to control the coating thickness in tight control. These problems were overcome by a two step deposition process where a YSZ layer of required thickness was produced by electrophoretic coating from an acetyl acetone bath at a voltage of 30-300V DC and sintered at 1300 deg C. The resulting porous YSZ layer was made impervious by chemical vapor infiltration (CVI) by the reaction between a mixture of vapors of YCl 3 and ZrCl 4 and steam at 1300 deg C as in the case of ECVD for a short

  9. A Pilot Chemical and Physical Stability Study of Extemporaneously Compounded Levetiracetam Intravenous Solution.

    Science.gov (United States)

    Raphael, Chenzira D; Zhao, Fang; Hughes, Susan E; Juba, Katherine M

    2015-01-01

    Levetiracetam is a commonly used antiepileptic medication for tumor-related epilepsy. However, the 100 mL intravenous (IV) infusion volume can be burdensome to imminently dying hospice patients. A reduced infusion volume would improve patient tolerability. The purpose of this study was to evaluate the stability of 1000 mg/25 mL (40 mg/mL) levetiracetam IV solution in sodium chloride 0.9%. We prepared levetiracetam 40 mg/mL IV solution and added it to polyvinyl chloride (PVC) bags, polyolefin bags, and polypropylene syringes. Triplicate samples of each product were stored at refrigeration (2-8°C) and analyzed on days 0, 1, 4, 7, and 14. Samples were subjected to visual inspection, pH measurement, and stability-indicating high-performance liquid chromatography (HPLC) analysis. Over the 2-week storage period, there was no significant change in visual appearance or pH for any of the stability samples. The HPLC results confirmed that all stability samples retained 94.2-101.3% of initial drug concentration and no degradation products or leachable material from the packaging materials were observed. We conclude that levetiracetam 1000 mg/25 mL IV solution in sodium chloride 0.9% is physically and chemically stable for up to 14 days under refrigeration in polypropylene syringes, PVC bags, and polyolefin bags.

  10. Electrical conductivity and chemical stability of BaCe0· 8− xAxGd0 ...

    Indian Academy of Sciences (India)

    ... K. BaCe0.7In0.1Gd0.2O3− and BaCe0.7Zr0.1Gd0.2O3− ceramics exhibit an excellent chemical stability against boiling water. Indium is a suitable doping element to promote the sintering densification and to enhance both electrical conductivity and chemical stability of Gd-doped BaCeO3 at operating temperatures.

  11. Chemical and enzymatic stability of amino acid prodrugs containing methoxy, ethoxy and propylene glycol linkers.

    Science.gov (United States)

    Gupta, Deepak; Gupta, Sheeba Varghese; Lee, Kyung-Dall; Amidon, Gordon L

    2009-01-01

    We evaluated the chemical and enzymatic stabilities of prodrugs containing methoxy, ethoxy and propylene glycol linkers in order to find a suitable linker for prodrugs of carboxylic acids with amino acids. l-Valine and l-phenylalanine prodrugs of model compounds (benzoic acid and phenyl acetic acid) containing methoxy, ethoxy and propylene glycol linkers were synthesized. The hydrolysis rate profile of each compound was studied at physiologically relevant pHs (1.2, 4, 6 and 7.4). Enzymatic hydrolysis of propylene glycol containing compounds was studied using Caco-2 homogenate as well as purified enzyme valacyclovirase. It was observed that the stability of the prodrugs increases with the linker length (propyl > ethyl > methyl). The model prodrugs were stable at acidic pH as compared to basic pH. It was observed that the prodrug with the aliphatic amino acid promoiety was more stable compared to its aromatic counterpart. The comparison between benzyl and the phenyl model compounds revealed that the amino acid side chain is significant in determining the stability of the prodrug whereas the benzyl or phenyl carboxylic acid had little or no effect on the stability. The enzymatic activation studies of propylene glycol linker prodrug in the presence of valacyclovirase and cell homogenate showed faster generation of the parent drug at pH 7.4. The half-life of prodrugs at pH 7.4 was more than 12 h, whereas in the presence of cell homogenate the half-lives were less than 1 h. Hydrolysis by Caco-2 homogenate generated the parent compound in two steps, where the prodrug was first converted to the intermediate, propylene glycol benzoate, which was then converted to the parent compound (benzoic acid). Enzymatic hydrolysis of propylene glycol containing prodrugs by valacyclovirase showed hydrolysis of the amino acid ester part to generate the propylene glycol ester of model compound (propylene glycol benzoate) as the major product. The amino acid prodrugs containing methoxy

  12. The chemical stability of TRISO-coated HTGR fuel. Pt. 1. Status report

    International Nuclear Information System (INIS)

    Groot, P.; Cordfunke, E.H.P.; Konings, R.J.M.

    1994-12-01

    The US fuel seemed to be more difficult to produce than the German fuel. Also the chemical stability of this fuel must be investigated. The conditions are more severe in the US concept than in the German concept. Oxidation of the graphite seems to be no problem, according to US HTGR concept. A ZrC coating seems to have a number of advantages with regard to the SiC coating: (1) Better retention, (2) no reaction with Pd, (3) no thermal dissociation. Only the oxidation resistance is worse than SiC. Also the maximum stress must be determined that the ZrC coating can have. (orig./HP)

  13. Assessment of soil stabilization by chemical extraction and bioaccumulation using earthworm, Eisenia fetida

    Science.gov (United States)

    Lee, Byung-Tae; Abd Aziz, Azilah; Han, Heop Jo; Kim, Kyoung-Woong

    2014-05-01

    Soil stabilization does not remove heavy metals from contaminated soil, but lowers their exposures to ecosystem. Thus, it should be evaluated by measuring the fractions of heavy metals which are mobile and/or bioavailable in soils. The study compared several chemical extractions which intended to quantify the mobile or bioaccessible fractions with uptake and bioaccumulation by earthworm, Eisenia fetida. Soil samples were taken from the abandoned mine area contaminated with As, Cd, Cu, Pb and/or Zn. To stabilize heavy metals, the soils were amended with limestone and steel slag at 5% and 2% (w/w), respectively. All chemical extractions and earthworm tests were applied to both the contaminated and the stabilized soils with triplicates. The chemical extractions consisted of six single extractions which were 0.01M CaCl2 (unbufferred), EDTA or DTPA (chelating), TCLP (acidic), Mehlich 3 (mixture), and aqua regia (peudo-total). Sequential extractions were also applied to fractionate heavy metals in soils. In earthworm tests, worms were exposed to the soils for uptake of heavy metals. After 28 days of exposure to soils, worms were transferred to clean soils for elimination. During the tests, three worms were randomly collected at proper sampling events. Worms were rinsed with DI water and placed on moist filter paper for 48 h for depuration. Filter paper was renewed at 24 h to prevent coprophagy. The worms were killed with liquid nitrogen, dried in the oven, and digested with aqua regia for ICP-MS analysis. In addition to the bioaccumulation, several toxicity endpoints were observed such as burrowing time, mortality, cocoon production, and body weight changes. Toxicokinetics was applied to determine the uptake and elimination heavy metals by the earthworms. Bioaccumulation factor (BAF) was estimated using total metal concentrations and body burdens. Pearson correlation and simple linear regression were applied to evaluate the relationship between metal fractions by single

  14. Chemical stability and defect formation in CaHfO3

    KAUST Repository

    Alay-E-Abbas, Syed Muhammad

    2014-04-01

    Defects in CaHfO3 are investigated by ab initio calculations based on density functional theory. Pristine and anion-deficient CaHfO 3 are found to be insulating, whereas cation-deficient CaHfO 3 is hole-doped. The formation energies of neutral and charged cation and anion vacancies are evaluated to determine the stability in different chemical environments. Moreover, the energies of the partial and full Schottky defect reactions are computed. We show that clustering of anion vacancies in the HfO layers is energetically favorable for sufficiently high defect concentrations and results in metallicity. © 2014 EPLA.

  15. Chemical stability and defect formation in CaHfO3

    KAUST Repository

    Alay-E-Abbas, Syed Muhammad; Nazir, Safdar; Mun Wong, Kin; Shaukat, Ali; Schwingenschlö gl, Udo

    2014-01-01

    Defects in CaHfO3 are investigated by ab initio calculations based on density functional theory. Pristine and anion-deficient CaHfO 3 are found to be insulating, whereas cation-deficient CaHfO 3 is hole-doped. The formation energies of neutral and charged cation and anion vacancies are evaluated to determine the stability in different chemical environments. Moreover, the energies of the partial and full Schottky defect reactions are computed. We show that clustering of anion vacancies in the HfO layers is energetically favorable for sufficiently high defect concentrations and results in metallicity. © 2014 EPLA.

  16. A nontoxic polypeptide oligomer with a fungicide potency under agricultural conditions which is equal or greater than that of their chemical counterparts.

    Directory of Open Access Journals (Sweden)

    Sara Monteiro

    Full Text Available There are literally hundreds of polypeptides described in the literature which exhibit fungicide activity. Tens of them have had attempted protection by patent applications but none, as far as we are aware, have found application under real agricultural conditions. The reasons behind may be multiple where the sensitivity to the Sun UV radiation can come in first place. Here we describe a multifunctional glyco-oligomer with 210 kDa which is mainly composed by a 20 kDa polypeptide termed Blad that has been previously shown to be a stable intermediary product of β-conglutin catabolism. This oligomer accumulates exclusively in the cotyledons of Lupinus species, between days 4 and 12 after the onset of germination. Blad-oligomer reveals a plethora of biochemical properties, like lectin and catalytic activities, which are not unusual per si, but are remarkable when found to coexist in the same protein molecule. With this vast range of chemical characteristics, antifungal activity arises almost as a natural consequence. The biological significance and potential technological applications of Blad-oligomer as a plant fungicide to agriculture, its uniqueness stems from being of polypeptidic in nature, and with efficacies which are either equal or greater than the top fungicides currently in the market are addressed.

  17. Physico-chemical stability of eribulin mesylate containing concentrate and ready-to-administer solutions.

    Science.gov (United States)

    Spindeldreier, Kirsten; Thiesen, Judith; Lipp, Hans-Peter; Krämer, Irene

    2014-06-01

    The aim of this study was to determine the stability of commercially available eribulin mesylate containing injection solution as well as diluted ready-to-administer solutions stored under refrigeration or at room temperature. Stability was studied by a novel developed stability-indicating reversed-phase high-performance liquid chromatography (RP-HPLC) assay with ultraviolet detection (detection wavelength 200 nm). Triplicate test solutions of eribulin mesylate containing injection concentrate (0.5 mg/mL) and with 0.9% sodium chloride solution diluted ready-to-administer preparations (0.205 mg/mL eribulin mesylate in polypropylene (PP) syringes, 0.020 mg/mL eribulin mesylate in polypropylene/polyethylene (PE) bags) were stored protected from light either at room temperature (25) or under refrigeration (2-8). Samples were withdrawn on day 0 (initial), 1, 3, 5, 7, 14, 21 and 28 of storage and assayed. Physical stability was determined by measuring the pH value once a week and checking for visible precipitations or colour changes. The stability tests revealed that concentrations of eribulin mesylate remained unchanged over a period of 28 days irrespective of concentration, container material or storage temperature. Neither colour changes nor visible particles have been observed. The pH value varied slightly over time but remained in the stability favourable range of 5-9. Eribulin mesylate injection (0.5 mg/mL) is physico-chemically stable over a period of 28 days after first puncture of the vial. After dilution with 0.9% NaCl vehicle solution, ready-to-administer eribulin mesylate injection solutions (0.205 mg/mL in PP syringe) and infusion solutions (0.02 mg/mL in prefilled PP/PE bags) are physico-chemically stable for a period of at least four weeks either refrigerated or stored at room temperature. For microbiological reasons storage under refrigeration is recommended.

  18. Effects of anticaking agents and relative humidity on the physical and chemical stability of powdered vitamin C.

    Science.gov (United States)

    Lipasek, Rebecca A; Taylor, Lynne S; Mauer, Lisa J

    2011-09-01

    Vitamin C is an essential nutrient that is widely used by the food industry in the powder form for both its nutritional and functional properties. However, vitamin C is deliquescent, and deliquescence has been linked to physical and chemical instabilities. Anticaking agents are often added to powder systems to delay or prevent caking, but little is known about their effect on the chemical stability of powders. In this study, various anticaking agents (calcium phosphate, calcium silicate, calcium stearate, corn starch, and silicon dioxide) were combined with sodium ascorbate at 2% and 50% w/w ratios and stored at various relative humidities (23%, 43%, 64%, 75%, 85%, and 98% RHs). Chemical and physical stability and moisture sorption were monitored over time. Additionally, saturated solution samples were stored at various pHs to determine the effect of surface pH and dissolution on the vitamin degradation rate. Storage RH, time, and anticaking agent type and ratio all significantly affected (P vitamin C stability. Silicon dioxide and calcium silicate (50% w/w) and calcium stearate (at both ratios) were the only anticaking agents to improve the physical stability of powdered sodium ascorbate while none of the anticaking agents improved its chemical stability. However, corn starch and calcium stearate had the least adverse effect on chemical stability. Dissolution rate and pH were also important factors affecting the chemical and physical stability of the powders. Therefore, monitoring storage environmental conditions and anticaking agent usage are important for understanding the stability of vitamin C. Anticaking agent type and ratio significantly affected the physical and chemical stability of vitamin C over time and over a range of RHs. No anticaking agent improved the chemical stability of the vitamin, and most caused an increase in chemical degradation even if physical stability was improved. It is possible that anticaking agents would greatly affect other

  19. Environmental impact of industrial sludge stabilization/solidification products: chemical or ecotoxicological hazard evaluation?

    Science.gov (United States)

    Silva, Marcos A R; Testolin, Renan C; Godinho-Castro, Alcione P; Corrêa, Albertina X R; Radetski, Claudemir M

    2011-09-15

    Nowadays, the classification of industrial solid wastes is not based on risk analysis, thus the aim of this study was to compare the toxicity classifications based on the chemical and ecotoxicological characterization of four industrial sludges submitted to a two-step stabilization/solidification (S/S) processes. To classify S/S products as hazardous or non-hazardous, values cited in Brazilian chemical waste regulations were adopted and compared to the results obtained with a battery of biotests (bacteria, alga and daphnids) which were carried out with soluble and leaching fractions. In some cases the hazardous potential of industrial sludge was underestimated, since the S/S products obtained from the metal-mechanics and automotive sludges were chemically classified as non-hazardous (but non-inert) when the ecotoxicity tests showed toxicity values for leaching and soluble fractions. In other cases, the environmental impact was overestimated, since the S/S products of the textile sludges were chemically classified as non-inert (but non-hazardous) while ecotoxicity tests did not reveal any effects on bacteria, daphnids and algae. From the results of the chemical and ecotoxicological analyses we concluded that: (i) current regulations related to solid waste classification based on leachability and solubility tests do not ensure reliable results with respect to environmental protection; (ii) the two-step process was very effective in terms of metal immobilization, even at higher metal-concentrations. Considering that S/S products will be subject to environmental conditions, it is of great interest to test the ecotoxicity potential of the contaminants release from these products with a view to avoiding environmental impact given the unreliability of ecotoxicological estimations originating from chemical analysis. Copyright © 2011 Elsevier B.V. All rights reserved.

  20. An investigation on the chemical stability and a novel strategy for long-term stabilization of diphenylalanine nanostructures in aqueous solution

    Directory of Open Access Journals (Sweden)

    H. Nezammahalleh

    2015-01-01

    Full Text Available The stability of diphenylalanine (FF microwires and microtubes in phosphate buffer solution was investigated and a novel strategy was developed for their chemical stabilization. This stability investigation was carried out by optical microscopy and by high performance liquid chromatography (HPLC. These microstructures dissolve in the solution depending upon their degree of FF saturation. The dissolution mechanisms of the structures in kinetically limited processes were found by accurately fitting the experimental dissolution data to a theoretical kinetic equation. The dissolution data were well fitted to the particular Avrami-Erofe’ev kinetic expression (R2 > 0.98. These findings suggest that the structures can be stabilized by a decrease in the hydration of the constituent molecules thorough a chemical conformational induced transition upon heat treatment. The stable microtubes were fabricated in a novel three step procedure consisting of the reduction of silver ions in unstable FF microtubes by a citrate reductant, the stabilization by chemical conformational induced transition upon heat treatment, and the consequent oxidation of the reduced silver by a persulfate oxidant. These materials were characterized by electron microscopy and powder X-ray diffraction techniques. The long-term stability of both structures was also confirmed by optical microscopy and HPLC.

  1. Chemical quality and oxidative stability of extra virgin olive oils from San Juan province (Argentina).

    Science.gov (United States)

    Ceci, Liliana N; Mattar, Susana B; Carelli, Amalia A

    2017-10-01

    This study provides information about the chemical quality (quality indices, fatty acid profile, total polyphenols (PPs), tocopherols and pigments) and oxidative stability index (OSI) of virgin olive oils of Arbequina, Changlot Real and Coratina cultivars (San Juan province, Argentina). The influence of the cultivar and the effect of earlier harvest dates on the yields (OY), quality and OSI of the oils were also evaluated. All the oils were classified as extra virgin. The OY (L/100kg) averaged: Arbequina=13.2, Changlot Real=21.3, Coratina=18.3. The oleic acid (O) percentage, oleic to linoleic plus linolenic ratio [O/(L+Ln)], PPs and OSI were highly dependent on cultivar (Arbequinachemical and nutritional quality, higher oxidative stability and a fatty acid profile according to the IOC trade standard. Copyright © 2017 Elsevier Ltd. All rights reserved.

  2. Preparation and chemical stability of iron-nitride-coated iron microparticles

    International Nuclear Information System (INIS)

    Luo Xin; Liu Shixiong

    2007-01-01

    Iron-nitride-coated iron microparticles were prepared by nitridation of the surface of iron microparticles with ammonia gas at a temperature of 510 deg. C. The phases, composition, morphology, magnetic properties, and chemical stability of the particles were studied. The phases were α-Fe, ε-Fe 3 N, and γ-Fe 4 N. The composition varied from the core to the surface, with 99.8 wt% Fe in the core, and 93.8 wt% Fe and 6 wt% N in the iron-nitride coating. The thickness of the iron-nitride coating was about 0.28 μm. The chemical stability of the microparticles was greatly improved, especially the corrosion resistance in corrosive aqueous media. The saturation magnetization and the coercive force were 17.1x10 3 and 68 kA/m, respectively. It can be concluded that iron-nitride-coated iron microparticles will be very useful in many fields, such as water-based magnetorheological fluids and polishing fluids

  3. Organic Redox Species in Aqueous Flow Batteries: Redox Potentials, Chemical Stability and Solubility

    Science.gov (United States)

    Wedege, Kristina; Dražević, Emil; Konya, Denes; Bentien, Anders

    2016-01-01

    Organic molecules are currently investigated as redox species for aqueous low-cost redox flow batteries (RFBs). The envisioned features of using organic redox species are low cost and increased flexibility with respect to tailoring redox potential and solubility from molecular engineering of side groups on the organic redox-active species. In this paper 33, mainly quinone-based, compounds are studied experimentially in terms of pH dependent redox potential, solubility and stability, combined with single cell battery RFB tests on selected redox pairs. Data shows that both the solubility and redox potential are determined by the position of the side groups and only to a small extent by the number of side groups. Additionally, the chemical stability and possible degradation mechanisms leading to capacity loss over time are discussed. The main challenge for the development of all-organic RFBs is to identify a redox pair for the positive side with sufficiently high stability and redox potential that enables battery cell potentials above 1 V. PMID:27966605

  4. Organic Redox Species in Aqueous Flow Batteries: Redox Potentials, Chemical Stability and Solubility

    Science.gov (United States)

    Wedege, Kristina; Dražević, Emil; Konya, Denes; Bentien, Anders

    2016-12-01

    Organic molecules are currently investigated as redox species for aqueous low-cost redox flow batteries (RFBs). The envisioned features of using organic redox species are low cost and increased flexibility with respect to tailoring redox potential and solubility from molecular engineering of side groups on the organic redox-active species. In this paper 33, mainly quinone-based, compounds are studied experimentially in terms of pH dependent redox potential, solubility and stability, combined with single cell battery RFB tests on selected redox pairs. Data shows that both the solubility and redox potential are determined by the position of the side groups and only to a small extent by the number of side groups. Additionally, the chemical stability and possible degradation mechanisms leading to capacity loss over time are discussed. The main challenge for the development of all-organic RFBs is to identify a redox pair for the positive side with sufficiently high stability and redox potential that enables battery cell potentials above 1 V.

  5. 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

  6. Bifurcation and stability analysis of rotating chemical spirals in circular domains: Boundary-induced meandering and stabilization

    Science.gov (United States)

    Bär, Markus; Bangia, Anil K.; Kevrekidis, Ioannis G.

    2003-05-01

    Recent experimental and model studies have revealed that the domain size may strongly influence the dynamics of rotating spirals in two-dimensional pattern forming chemical reactions. Hartmann et al. [Phys. Rev. Lett. 76, 1384 (1996)], report a frequency increase of spirals in circular domains with diameters substantially smaller than the spiral wavelength in a large domain for the catalytic NO+CO reaction on a microstructured platinum surface. Accompanying simulations with a simple reaction-diffusion system reproduced the behavior. Here, we supplement these studies by a numerical bifurcation and stability analysis of rotating spirals in a simple activator-inhibitor model. The problem is solved in a corotating frame of reference. No-flux conditions are imposed at the boundary of the circular domain. At large domain sizes, eigenvalues and eigenvectors very close to those corresponding to infinite medium translational invariance are observed. Upon decrease of domain size, we observe a simultaneous change in the rotation frequency and a deviation of these eigenvalues from being neutrally stable (zero real part). The latter phenomenon indicates that the translation symmetry of the spiral solution is appreciably broken due to the interaction with the (now nearby) wall. Various dynamical regimes are found: first, the spiral simply tries to avoid the boundary and its tip moves towards the center of the circular domain corresponding to a negative real part of the “translational” eigenvalues. This effect is noticeable at a domain radius of R

  7. Effect of Cation Ordering on the Performance and Chemical Stability of Layered Double Perovskite Cathodes

    Directory of Open Access Journals (Sweden)

    Carlos Bernuy-Lopez

    2018-01-01

    Full Text Available The effect of A-site cation ordering on the cathode performance and chemical stability of A-site cation ordered LaBaCo2O5+δ and disordered La0.5Ba0.5CoO3−δ materials are reported. Symmetric half-cells with a proton-conducting BaZr0.9Y0.1O3−δ electrolyte were prepared by ceramic processing, and good chemical compatibility of the materials was demonstrated. Both A-site ordered LaBaCo2O5+δ and A-site disordered La0.5Ba0.5CoO3−δ yield excellent cathode performance with Area Specific Resistances as low as 7.4 and 11.5 Ω·cm2 at 400 °C and 0.16 and 0.32 Ω·cm2 at 600 °C in 3% humidified synthetic air respectively. The oxygen vacancy concentration, electrical conductivity, basicity of cations and crystal structure were evaluated to rationalize the electrochemical performance of the two materials. The combination of high-basicity elements and high electrical conductivity as well as sufficient oxygen vacancy concentration explains the excellent performance of both LaBaCo2O5+δ and La0.5Ba0.5CoO3−δ materials at high temperatures. At lower temperatures, oxygen-deficiency in both materials is greatly reduced, leading to decreased performance despite the high basicity and electrical conductivity. A-site cation ordering leads to a higher oxygen vacancy concentration, which explains the better performance of LaBaCo2O5+δ. Finally, the more pronounced oxygen deficiency of the cation ordered polymorph and the lower chemical stability at reducing conditions were confirmed by coulometric titration.

  8. Rescue of glaucoma-causing mutant myocilin thermal stability by chemical chaperones

    Science.gov (United States)

    Burns, J. Nicole; Orwig, Susan D.; Harris, Julia L.; Watkins, J. Derrick; Vollrath, Douglas; Lieberman, Raquel L.

    2010-01-01

    Mutations in myocilin cause an inherited form of open angle glaucoma, a prevalent neurodegenerative disorder associated with increased intraocular pressure. Myocilin forms part of the trabecular meshwork extracellular matrix presumed to regulate intraocular pressure. Missense mutations, clustered in the olfactomedin (OLF) domain of myocilin, render the protein prone to aggregation in the endoplasmic reticulum of trabecular meshwork cells, causing cell dysfunction and death. Cellular studies have demonstrated temperature-sensitive secretion of myocilin mutants, but difficulties in expression and purification have precluded biophysical characterization of wild-type (wt) myocilin and disease-causing mutants in vitro. We have overcome these limitations by purifying wt and select glaucoma-causing mutant (D380A, I477N, I477S, K423E) forms of the OLF domain (228–504) fused to maltose binding protein (MBP) from E. coli. Monomeric fusion proteins can be isolated in solution. To determine the relative stability of wt and mutant OLF domains, we developed a fluorescence thermal stability assay without removal of MBP, and provide the first direct evidence that mutated OLF is folded but less thermally stable than wt. We tested the ability of seven chemical chaperones to stabilize mutant myocilin. Only sarcosine and trimethylamine N-oxide were capable of shifting the melting temperature of all mutants tested to near that of wt OLF. Our work lays the foundation for the identification of tailored small molecules capable of stabilizing mutant myocilin and promoting secretion to the extracellular matrix, to better control intraocular pressure and ultimately delay the onset of myocilin glaucoma. PMID:20334347

  9. Wet-chemical passivation of InAs: toward surfaces with high stability and low toxicity.

    Science.gov (United States)

    Jewett, Scott A; Ivanisevic, Albena

    2012-09-18

    In a variety of applications where the electronic and optical characteristics of traditional, siliconbased materials are inadequate, recently researchers have employed semiconductors made from combinations of group III and V elements such as InAs. InAs has a narrow band gap and very high electron mobility in the near-surface region, which makes it an attractive material for high performance transistors, optical applications, and chemical sensing. However, silicon-based materials remain the top semiconductors of choice for biological applications, in part because of their relatively low toxicity. In contrast to silicon, InAs forms an unstable oxide layer under ambient conditions, which can corrode over time and leach toxic indium and arsenic components. To make InAs more attractive for biological applications, researchers have investigated passivation, chemical and electronic stabilization, of the surface by adlayer adsorption. Because of the simplicity, low cost, and flexibility in the type of passivating molecule used, many researchers are currently exploring wet-chemical methods of passivation. This Account summarizes much of the recent work on the chemical passivation of InAs with a particular focus on the chemical stability of the surface and prevention of oxide regrowth. We review the various methods of surface preparation and discuss how crystal orientation affects the chemical properties of the surface. The correct etching of InAs is critical as researchers prepare the surface for subsequent adlayer adsorption. HCl etchants combined with a postetch annealing step allow the tuning of the chemical properties in the near-surface region to either arsenic- or indium-rich environments. Bromine etchants create indium-rich surfaces and do not require annealing after etching; however, bromine etchants are harsh and potentially destructive to the surface. The simultaneous use of NH(4)OH etchants with passivating molecules prevents contact with ambient air that can

  10. Stabilization of contaminated soil and wastewater with chemically bonded phosphate ceramics

    International Nuclear Information System (INIS)

    Wagh, A.S.; Jeong, S.Y.; Singh, D.

    1997-01-01

    At Argonne National Laboratory, we have developed chemically Bonded phosphate ceramic (CBPC) technology to stabilize the U.S. Department of Energy's problem mixed waste streams, for which no other stabilization technology is suitable. In this technology, solid waste is mixed with MgO and reacted with aqueous solutions of phosphoric acid or acid phosphates at room temperature to form a slurry that sets in ∼2 h into a hard and dense ceramic waste form. Initial studies involved stabilizing the surrogate waste streams and then testing the waste forms for leaching of contaminants. After achieving satisfactory performance of the waste forms, we next incorporated actual waste streams at bench scale and produced waste forms that were then tested with the Toxicity Characteristic Leaching Procedure (TCLP). This presentation deals with stabilization of soil contaminated with Cd, Cr, Pb, Ag, Ba, and Hg, and of low-level radioactive wastewater. To enhance the contaminant levels in the soil, we further spiked the soil with additional amounts of Cd, Cr, Pb, and Hg. Both the soil and the wastewater were incorporated in the same waste form by stabilizing them with the CBPC process. The waste forms had a total waste loading of ∼77 wt.% and were dense with an open porosity of 2.7 vol.% and a density of 2.17 g/cm 3 . Compression strength was 4910 psi. The TCLP results showed excellent immobilization of all the RCRA metals, and radioactive contaminant levels were below the detection limit of 0.2 pCi/mL. Long-term leaching studies using the ANS 16.1 procedure showed that the retention of contaminants is excellent and comparable to or better than most of other stabilization processes. These results demonstrate that the CBPC process is a very superior process for treatment of low level mixed wastes; we therefore conclude that the CBPC process is well suited to the treatment of low-level mixed waste streams with high waste loading

  11. Functional and chemical stability of a medicinal herb, Artemisia capillaris, following gamma sterilization

    Energy Technology Data Exchange (ETDEWEB)

    Jung, Uhee; Jeong, Ill Yun; Bae, Mun Hyoung; Byun, Myung Woo; Jo, Sung Kee [Radiation Research Center for Biotechnology, Advanced Radiation Technology Institute, Korea Atomic Energy Research Institute, Jeongeup (Korea, Republic of)

    2007-08-15

    The stability of functional and chemical properties of gamma-irradiated (10 kGy) Artemisia capillaris, a widely used herb in the traditional Oriental medicine, was investigated. Functional properties of the extracts of gamma-irradiated and non-irradiated A. capillaris were compared in antioxidant activities, such as 1,1-diphenyl-2-picryl hydrazyl (DPPH) radical and superoxide anion radical scavenging, lipid peroxidation inhibition, and protection of lymphocyte and plasmid DNA. Their chemical properties were assessed by HPLC analysis, comparing with chlorogenic acid and caffeic acid, which were isolated from ethylacetate fraction as major compounds with strong antioxidant activities. No significant difference in functional properties between irradiated and non-irradiated A. capillaris was found in all antioxidant assays. Also HPLC analysis of ethyl acetate fractions of irradiated and non-irradiated A. capillaris revealed the preservation of chlorogenic acid ({sub t}R=3.124 min) and caffeic acid ({sub t}R=3.672 min), and showed almost the same pattern in the general peaks. These results suggest that the chemical components and antioxidant properties of A. capillaris are not affected largely by gamma-ray irradiation. Therefore, this study may provide evidence that the irradiated herbs retain their potential functional properties.

  12. Comment on the Long-Term Chemical and Mineralogical Stability of the Buffer

    International Nuclear Information System (INIS)

    Arthur, Randy; Apted, Mick; Stenhouse, Mike

    2005-03-01

    This report examines concepts and data that SKB may use to assess the long-term chemical and mineralogical evolution of bentonite barriers in a KBS-3 repository for spent nuclear fuel. Three interrelated topics are considered: mineral chemistry of the smectite clays; thermodynamic stability of the smectite clays; and bentonite-water interactions during the early thermal period of repository evolution. Smectites are complex solid solutions having variable compositions resulting from ionic substitutions on exchange, octahedral and tetrahedral sites in the crystalline lattice. Although little is known about the mechanisms and rates of reactions involving the latter two sites, abundant observational evidence from natural systems suggests that such reactions could occur to an appreciable extent in the buffer over the million year time frame being considered for an intact canister. We are not aware of any efforts in SKB's current modeling strategy to account for such reactions, and therefore question whether the strategy is appropriate for modeling the long-term chemical evolution of the buffer and associated potential effects on the desirable physical and rheological properties of this barrier material. The variable chemistry of smectites affects their thermodynamic stability. Models of smectite-water equilibria use either a fixed stoichiometric composition to approximate representative smectite varieties, or account for compositional variations using solid solution models and ideal mixing relations among thermodynamic components. In either case the thermodynamic properties of a specific smectite composition or of individual solid-solution components must usually be estimated. Recent reports suggest that SKB will not account explicitly for the thermodynamic properties of smectite in its models of bentonite-water interactions. Rather, the models will assume that this clay mineral has a fixed, though unspecified, composition representing an ion-exchanger phase. This phase

  13. YNi and its hydrides: Phase stabilities, electronic structures and chemical bonding properties from first principles

    International Nuclear Information System (INIS)

    Matar, S.F.; Nakhl, M.; Al Alam, A.F.; Ouaini, N.; Chevalier, B.

    2010-01-01

    Graphical abstract: Base centered orthorhombic YNiH X structure. For x = 3, only H1 and H2 are present. Highest hydrogen content YNiH 4 is obtained when H3 are added. - Abstract: Within density functional theory, establishing the equations of states of YNi in two different controversial structures in the literature, leads to determine the orthorhombic FeB-type as the ground state one with small energy difference. For YNiH 3 and YNiH 4 hydrides crystallizing in the orthorhombic CrB-type structure the geometry optimization and the ab initio determination of the H atomic positions show that the stability of hydrogen decreases from the tri- to the tetra- hydride. New states brought by hydrogen within the valence band lead to its broadening and to enhanced localization of metal density of states. The chemical bonding analysis shows a preferential Ni-H bonding versus Y-H.

  14. YNi and its hydrides: Phase stabilities, electronic structures and chemical bonding properties from first principles

    Energy Technology Data Exchange (ETDEWEB)

    Matar, S.F., E-mail: matar@icmcb-bordeaux.cnrs.fr [CNRS, Universite de Bordeaux, ICMCB, 87 avenue du Docteur Albert Schweitzer, F-33608 Pessac (France); Nakhl, M. [Universite Libanaise, Laboratoire de Chimie-Physique des Materiaux LCPM, Fanar (Lebanon); Al Alam, A.F.; Ouaini, N. [Universite Saint-Esprit de Kaslik, Faculte des Sciences et de Genie Informatique, Jounieh (Lebanon); Chevalier, B. [CNRS, Universite de Bordeaux, ICMCB, 87 avenue du Docteur Albert Schweitzer, F-33608 Pessac (France)

    2010-11-25

    Graphical abstract: Base centered orthorhombic YNiH{sub X} structure. For x = 3, only H1 and H2 are present. Highest hydrogen content YNiH{sub 4} is obtained when H3 are added. - Abstract: Within density functional theory, establishing the equations of states of YNi in two different controversial structures in the literature, leads to determine the orthorhombic FeB-type as the ground state one with small energy difference. For YNiH{sub 3} and YNiH{sub 4} hydrides crystallizing in the orthorhombic CrB-type structure the geometry optimization and the ab initio determination of the H atomic positions show that the stability of hydrogen decreases from the tri- to the tetra- hydride. New states brought by hydrogen within the valence band lead to its broadening and to enhanced localization of metal density of states. The chemical bonding analysis shows a preferential Ni-H bonding versus Y-H.

  15. Chemical stability of {gamma}-butyrolactone-based electrolytes for aluminium electrolytic capacitors

    Energy Technology Data Exchange (ETDEWEB)

    Ue, Makoto [Mitsubishi Chemical Corp., Tsukuba Research Center, Ibaraki (Japan); Takeda, Masayuki [Mitsubishi Chemical Corp., Tsukuba Research Center, Ibaraki (Japan); Suzuki, Yoko [Mitsubishi Chemical Corp., Tsukuba Research Center, Ibaraki (Japan); Mori, Shoichiro [Mitsubishi Chemical Corp., Tsukuba Research Center, Ibaraki (Japan)

    1996-06-01

    {gamma}-Butyrolactone-based electrolytes have been used as the operating electrolytes for aluminum electrolytic capacitors. The chemical stability of these electrolytes at elevated temperatures has been examined by monitoring the decrease in their electrolytic conductivities. The deteriorated electrolytes were analyzed by gas and liquid chromatography and the conductivity decrease was directly correlated with the loss of acid components. In quaternary ammonium hydrogen maleate/{gamma}-butyrolactone electrolytes, the maleate anion decomposed by decarboxylation resulting in a complex polymer containing polyester and polyacrylate structures. Quaternary ammonium benzoate/{gamma}-butyrolactone electrolytes decomposed by SN2 reactions giving alkyl benzoates and trialkylamines. The deterioration of the carboxylate salt/{gamma}-butyrolactone electrolytes was accelerated by electrolysis. (orig.)

  16. Assessment of chromatographic methods for the chemical stability of a new miconazole nitrate cream

    International Nuclear Information System (INIS)

    Garcia Pulpeiro, Oscar; Calzadilla Aguiar, Wendy; Rodriguez Bencomo, Wendy

    2013-01-01

    To assess the chromatographic methods for the chemical stability of a new 2 % miconazol nitrate cream. arious degradation conditions were firstly used in the raw material miconazole nitrate in order to obtain the possible degradation products of this drug and to evaluate them by thin layer chromatography-based method, which was validated to identify the degradation products in the new cream. The performance of the official method based on high resolution liquid chromatography and reported in British Pharmacopoeia 2010 was evaluated, and its selectivity against the possible degradation products were also analyzed. Both chromatographic methods were applied to the analysis of cream samples from the three pilot batches under heat stress for 30 days

  17. Colour stability, staining and roughness of silorane after prolonged chemical challenges

    DEFF Research Database (Denmark)

    Benetti, Ana Raquel; Ribeiro de Jesus, Vivian Cristiane Bueno; Martinelli, Natan Luiz

    2013-01-01

    methacrylate or silorane composites. Specimens were individually stored at 37°C in 0.02 N citric acid, 0.02 N phosphoric acid, 75% ethanol or distilled water for 7, 14, 21 and 180 days, when new measurements were performed. A staining test was performed after the chemical challenge by immersion in coffee...... considered acceptable (although significantly different) after immersion in water, citric acid, phosphoric acid or ethanol, but were unacceptable for the silorane composite immersed in ethanol for 180 days. The methacrylate-based resins stored in ethanol were significantly more stained by coffee than those...... stored in other media. The silorane composite demonstrated no staining, but increased roughness, when compared to the methacrylate-based resins. CONCLUSIONS: No effect of the immersion solution was noticed on roughness of the investigated materials. Ethanol influenced colour stability and staining...

  18. High-temperature stability of chemically vapor-deposited tungsten-silicon couples rapid thermal annealed in ammonia and argon

    Energy Technology Data Exchange (ETDEWEB)

    Broadbent, E.K.; Morgan, A.E.; Flanner, J.M.; Coulman, B.; Sadana, D.K.; Burrow, B.J.; Ellwanger, R.C.

    1988-12-15

    A rapid thermal anneal (RTA) in an NH/sub 3/ ambient has been found to increase the thermal stability of W films chemically vapor deposited (CVD) on Si. W films deposited onto single-crystal Si by low-pressure CVD were rapid thermal annealed at temperatures between 500 and 1100 /sup 0/C in NH/sub 3/ and Ar ambients. The reactions were studied using Rutherford backscattering spectrometry, x-ray diffraction, Auger electron spectroscopy, transmission electron microscopy, and four-point resistivity probe. High-temperature (greater than or equal to1000 /sup 0/C) RTA in Ar completely converted W into the low resistivity (31 ..mu cap omega.. cm) tetragonal WSi/sub 2/ phase. In contrast, after a prior 900 /sup 0/C RTA in NH/sub 3/, N inclusion within the W film and at the W/Si interface almost completely suppressed the W-Si reaction. Detailed examination, however, revealed some patches of WSi/sub 2/ formed at the interface accompanied by long tunnels extending into the substrate, and some crystalline precipitates in the substrate close to the interface. The associated interfacial contact resistance was only slightly altered by the 900 /sup 0/C NH/sub 3/ anneal. The NH/sub 3/-treated W film acted as a diffusion barrier in an Al/W/Si contact metallurgy up to at least 550 /sup 0/C, at which point some increase in contact resistance was measured.

  19. Isoparaffinic diluents for tri-n-butyl phosphate. Chemical, radiation-chemical stability, effect on tetravalent plutonium and thorium extraction

    International Nuclear Information System (INIS)

    Renard, E.V.; Pyatibratov, Yu.P.; Neumoev, N.V.; Chizhov, A.A.; Kulikov, I.A.; Gol'dfarb, Yu.Ya.; Sirotkina, I.G.; Semenova, T.I.

    1989-01-01

    By means of catalytic hydroisomerization of the n-paraffinic raw material in a reactor using alumino-platinum catalysts, there was attained a 45-90% degree of conversion of n-paraffins into branched iso-paraffins with mono- and dimethyl structure. From a batch of extensively isomerized n-paraffins, by carrying out the operations of distillation of the light (benzine) fraction, dearomatization, de-n-paraffinization and fractional distillation on a rectification column, isoparaffinic (99%) concentrates were obtained with a constant molecular weight, from iso-C 10 to isoC 15 . The solubility of plutonium and thorium nitrates in 30% solutions of TBP in iso-paraffins (mixtures of iso-paraffins with the same number of C-atoms) increases with decrease in the molecular weight of the iso-paraffin; a system with a 30% TBP in a mixture of iso-decanes practically does not stratify (∼104 g Pu/liter, 22-25 degree C). Nevertheless, a twofold increase (compared with NP) of the maximally permissible (up to the formation of the third phase) concentration, is attained when iso-paraffins are introduced into NP with a similar molecular composition in a 1:1 ratio. With respect to the main requirements demanded of diluents for radiochemical extractional operations, such as density, viscosity, boiling point, flash point, and freezing point, the chemical stability and radiation resistance, content of radioruthenium and radiozirconium, rate of stratification of two-phase systems, the synthetic iso-paraffin-containing solvents are as suitable as n-paraffins

  20. Chemical stabilization of subgrade soil for the strategic expeditionary landing field

    Science.gov (United States)

    Conaway, M. H.

    1983-06-01

    The Strategic Expeditionary Landing Field (SELF) is a military expeditionary-type airfield with an aluminum matted surface that is designed for sustained tactical and cargo airlift operations in an amphibious objective area. Because of the operational traffic parameters such as loads of the various types of aircraft, tire pressures and volume of traffic, a base layer must be constructed over subgrade soil support conditions which may be only marginal. The base layer could be constructed with conventional soil construction techniques (compaction) and yield the required strength. It would be difficult, however, to maintain this strength for the required one-year service life under many climatic conditions due to the degrading effects of water on the support capacity of many soils. Chemical soil stabilization with lime, portland cement and asphalt stabilizing agents could be used to treat the soil. These additives, when properly mixed with certain types of soils, initiate reactions which will increase soil support strength and enhance durability (resistance to the degrading effects of water). Technically, this procedure is quite viable but logistically, it may not be feasible.

  1. Chemical and physical stability of smectites and illite in electrolyte solutions: experimental study at 150 C

    International Nuclear Information System (INIS)

    Boutiche, M.

    1995-01-01

    Chemical interactions between electrolytic solutions commonly used i drilling muds and clays have been studies under P-T conditions similar to those of drillings (150 deg C) in order to determine the eventual consequences on the stability of clay rich formations. The experimental work has been carried out using several solutions (water, NaOH (pH 8, 10, 12), KCI (0,1, 1 2 mol./l), sea water, and K 2 CO 3 ) and clay minerals with low to high amounts of swelling layers (smectite (Na, Na-Ca, Ca), mixed layered illite-smectite minerals). Run products are studied by X-ray diffraction and electronic microprobe. Smectite layers show series of mineralogical changes (cation exchange in the interlayer site, formation of non-swelling layers, hydrolysis), which, however, do not yield to the formation of new minerals, except in the case of the interaction with K 2 CO 3 at 150 deg C (zeolite crystallisation). Cation exchange in the interlayer depends on the nature of the cation, cation concentration in the solution, exchange constants, and liquid/solid ratio. In dilute solutions ( 1 mol./l), because they favour the collapse of swelling layers, and dispersion. Solutions of K 2 CO 3 at 150 deg C are at the origin of the transformation of smectite to zeolites, and high pH - highly saline solutions are rather aggressive, and would probably not stabilize the argilites. (author)

  2. Stabilization of heavy oil-water emulsions using a bio/chemical emulsifier mixture

    Energy Technology Data Exchange (ETDEWEB)

    Farahbakhsh, A.; Taghizadeh, M.; Movagharnejad, K. [Chemical Engineering Department, Babol University of Technology, Babol (Iran, Islamic Republic of); Yakhchali, B. [National Institute of Genetic Engineering and Biotechnology, Tehran (Iran, Islamic Republic of)

    2011-11-15

    In this study, the viscosity reduction of heavy oil has been investigated through the formation of oil-water emulsion using a bio/chemical emulsifier mixture. Four bioemulsifiers from indigenous Rhodococcus ergthropolis and Bacillus licheniformis strains were used to stabilize a highly-viscous oil-in-water emulsion. The Taguchi method with an L{sub 9} orthogonal array design was used to investigate the effect of various control factors on the formation of the oil/water emulsions. An emulsion with lowest viscosity was formed using ACO4 strain. The substantial stability of the oil-in-water emulsion allows the heavy oil to be transported practically over long distances or remain stationary for a considerable period of time prior to utilization. As the result of Taguchi analysis, the temperature and concentration of the emulsifier had a significant influence on viscosity reduction of the emulsion. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  3. Thulium oxide fuel characterization study: Part 2, Environmental behavior and mechanical, thermal and chemical stability enhancement

    International Nuclear Information System (INIS)

    Nelson, C.A.

    1970-12-01

    A study was performed of the correlation between fuel form stability and exposure environment of (temperature and atmosphere). 100% Tm 2 O 3 , 80% Tm 2 O 3 /20% Yb 2 O 3 and 100% Yb 2 O 3 wafers were subjected to air, dynamic vacuum and static vacuum at temperatures to 2000 0 C for times to 100 hours. Results showed the Tm 2 O 3 /Yb 2 O 3 cubic structure to be unaffected by elemental levels of iron, aluminum, magnesium and silicon and unaffected by the environmental conditions imposed on the wafers. A second task emphasized the optimization of the thermal, mechanical and chemical stability of Tm 2 O 3 fuel forms. Enhancement was sought through process variable optimization and the addition of metal oxides to Tm 2 O 3 . CaO, TiO 2 and Al 2 O 3 were added to form a grain boundary precipitate to control fines generation. The presence of 1% additive was inadequate to depress the melting point of Tm 2 O 3 or to change the cubic crystalline structure of Tm 2 O 3 /Yb 2 O 3 . Tm 2 O 3 /Yb 2 O 3 wafers containing CaO developed a grain boundary phase that improved the resistance to fines generation. The presence of Yb 2 O 3 did not appear to measurably influence behavior

  4. Aerobic stability, chemical composition and ruminal degradability of sugarcane silage with glycerin from biodiesel

    Directory of Open Access Journals (Sweden)

    Marco Antonio Bensimon Gomes

    2015-06-01

    Full Text Available The experiment was performed with the objective of studying the ensiled sugarcane silage with 0, 5, 10, 15 and 20% of glycerin in experimental PVC silos. The aerobic stability was assessed by measuring the pH and the temperature of the silage at 0, 24, 48, 72, 96 and 120h. The chemical composition, the levels of non-fiber carbohydrates (NFC and the total digestible nutrients (TDN were evaluated. The in vitro digestibility of dry matter (IVDDM and the in vitro digestibility of the cell wall (IVDCW in the silages were evaluated. In three fistulated cattle the in situ degradability of dry matter (DM and the disappearance percentage of the neutral detergent fiber (NDF in samples incubated at 0, 2, 6, 12, 24, 48, 72 and 96h were analyzed. The experimental design was completely randomized and the statistical analyzes were done using Bayesian inference. Increases were observed in DM, TDN, mineral matter, NFC and reductions in NDF, acid detergent fiber, crude protein and ether extract as the inclusion of glycerin was higher. IVDDM increased (P <0.05 in silage with 15 and 20% of glycerin in relation to those with 0, 5 and 10%. The IVDCW at levels of 10, 15 and 20% of glycerin was higher (P <0.05 compared to the other treatments. Increases were observed in the soluble portion (a, a reduction in the insoluble fraction (b, and an increase in the degradability fraction constant (c of the silages with 5, 10, 15 and 20% of glycerin (P <0.05 compared to the control. Glycerin improved aerobic stability while maintaining a low pH and temperature during the observation period at levels of 15 and 20% of glycerin against the silage with 0, 5 and 10%. These results indicate glycerin as a promising additive for sugarcane silage, being able to enhance energy density and improve the aerobic stability of the ensiled matter when its inclusion is from 10 to 20%.

  5. Chemical stability of a cold-active cellulase with high tolerance toward surfactants and chaotropic agent

    Directory of Open Access Journals (Sweden)

    Thaís V. Souza

    2016-03-01

    Full Text Available CelE1 is a cold-active endo-acting glucanase with high activity at a broad temperature range and under alkaline conditions. Here, we examined the effects of pH on the secondary and tertiary structures, net charge, and activity of CelE1. Although variation in pH showed a small effect in the enzyme structure, the activity was highly influenced at acidic conditions, while reached the optimum activity at pH 8. Furthermore, to estimate whether CelE1 could be used as detergent additives, CelE1 activity was evaluated in the presence of surfactants. Ionic and nonionic surfactants were not able to reduce CelE1 activity significantly. Therefore, CelE1 was found to be promising candidate for use as detergent additives. Finally, we reported a thermodynamic analysis based on the structural stability and the chemical unfolding/refolding process of CelE1. The results indicated that the chemical unfolding proceeds as a reversible two-state process. These data can be useful for biotechnological applications.

  6. Chemical compounds and mechanisms involved in the formation and stabilization of foam in sparkling wines.

    Science.gov (United States)

    Kemp, Belinda; Condé, Bruna; Jégou, Sandrine; Howell, Kate; Vasserot, Yann; Marchal, Richard

    2018-02-08

    The visual properties of sparkling wine including foam and bubbles are an indicator of sparkling wine quality. Foam properties, particularly foam height (FH) and foam stability (TS), are significantly influenced by the chemical composition of the wine. This review investigates our current knowledge of specific chemical compounds and, the mechanisms by which they influence the foam properties of sparkling wines. Grape and yeast proteins, amino acids, polysaccharides, phenolic compounds, organic acids, fatty acids, ethanol and sugar are examined with respect to their contribution to foam characteristics in sparkling wines made with the Traditional, Transfer, and Charmat and carbonation methods. Contradictory results have been identified that appear to be due to the analytical methods used to measure and quantify compounds and foam. Biopolymer complexes are discussed and absent knowledge with regards to thaumatin-like proteins (TLPs), polysaccharides, amino acids, oak-derived phenolic compounds and organic acids are identified. Future research is also likely to concentrate on visual analysis of sparkling wines by in-depth imaging analysis and specific sensory analysis techniques.

  7. Silver-mediated base pairings: towards dynamic DNA nanostructures with enhanced chemical and thermal stability

    International Nuclear Information System (INIS)

    Swasey, Steven M; Gwinn, Elisabeth G

    2016-01-01

    The thermal and chemical fragility of DNA nanomaterials assembled by Watson–Crick (WC) pairing constrain the settings in which these materials can be used and how they can be functionalized. Here we investigate use of the silver cation, Ag + , as an agent for more robust, metal-mediated self-assembly, focusing on the simplest duplex building blocks that would be required for more elaborate Ag + –DNA nanostructures. Our studies of Ag + -induced assembly of non-complementary DNA oligomers employ strands of 2–24 bases, with varied base compositions, and use electrospray ionization mass spectrometry to determine product compositions. High yields of duplex products containing narrowly distributed numbers of Ag + can be achieved by optimizing solution conditions. These Ag + -mediated duplexes are stable to at least 60 mM Mg 2+ , higher than is necessary for WC nanotechnology schemes such as tile assemblies and DNA origami, indicating that sequential stages of Ag + -mediated and WC-mediated assembly may be feasible. Circular dichroism spectroscopy suggests simple helical structures for Ag + -mediated duplexes with lengths to at least 20 base pairs, and further indicates that the structure of cytosine-rich duplexes is preserved at high urea concentrations. We therefore propose an approach towards dynamic DNA nanomaterials with enhanced thermal and chemical stability through designs that combine sturdy silver-mediated ‘frames’ with WC paired ‘pictures’. (paper)

  8. Preparing for chemical terrorism: a study of the stability of expired pralidoxime (2-PAM).

    Science.gov (United States)

    Hoffman, Robert S; Mercurio-Zappala, Maria; Bouchard, Nicole; Ravikumar, Padinjarekuttu; Goldfrank, Lewis

    2012-03-01

    Oximes such as pralidoxime (2-PAM) are essential antidotes for life-threatening organophosphate poisoning. Unfortunately, oximes are expensive, have limited use, and have short shelf lives. As such, maintaining large stockpiles in preparation for terrorist activity is not always possible. We have demonstrated that atropine is stable well beyond its labeled shelf life and that recently expired 2-PAM was clinically efficacious in a series of poisoned patients. Because 2-PAM is often dosed empirically, clinical improvement does not guarantee pharmacological stability. We therefore chose to analyze the chemical stability of expired 2-PAM. Samples of lyophylized 2-PAM were maintained according to the manufacturer's recommendations for 20 years beyond the published shelf life. We studied 2-PAM contained in a MARK I autoinjector that was stored properly for 3 years beyond its expiration date. An Agilent LC/MSD 1100 with diode-array detector and an Agilent Sorbax SB-C-18, 4.6 × 150-mm, 5-μm column were used with the following solvent systems: water with 0.01% trifluoroacetic acid and methanol with 0.01% trifluoroacetic acid. Fresh reagent grade 2-PAM was used as a standard. Results were repeated for consistency. Lyophylized 2-PAM was a white powder that was clear and colorless in solution. Liquid chromatography was identical to the standard and resulted in 2 isolated peaks with identical mass spectra, suggesting that they are stereoisomers. The autoinjector discharged a clear, yellowish solution. In addition to the 2 peaks identified for lyophylized 2-PAM, a small third peak was identified with a mass spectra corresponding to the reported N -methyl pyridinium carboxaldehyde degradation product. When properly stored, lyophylized 2-PAM appears to be chemically stable well beyond its expiration date. Although the relative amount of degradation product found in solubilized (autoinjector) 2-PAM was small, it is unclear whether this may be toxic and therefore is of concern

  9. Chemical Stability Analysis of Hair Cleansing Conditioners under High-Heat Conditions Experienced during Hair Styling Processes

    Directory of Open Access Journals (Sweden)

    Derek A. Drechsel

    2018-03-01

    Full Text Available Chemical stability is a key component of ensuring that a cosmetic product is safe for consumer use. The objective of this study was to evaluate the chemical stability of commercially available hair cleansing conditioners subjected to high heat stresses from the styling processes of blow drying or straightening. Two hair cleansing conditioners were subjected to temperatures of 60 °C and 185 °C to simulate the use of a blow dryer or flatiron hair straightener, respectively and analyzed via Gas Chromatography-Mass Spectrometry (GC-MS, High-Performance Liquid Chromatography-UV (HPLC and Fourier-Transform Infrared Spectroscopy (FT-IR to capture a chemical profile of the samples. The resulting spectra from matched heated and unheated samples were compared to identify any changes in chemical composition. Overall, no differences in the spectra were observed between the heated and unheated samples at both temperatures evaluated. Specifically, no new peaks were observed during analysis, indicating that no degradation products were formed. In addition, all chemicals identified during GC-MS analysis were known listed ingredients of the products. In summary, no measurable changes in chemical composition were observed in the hair cleansing conditioner samples under high-heat stress conditions. The presented analytical methods can serve as an initial screening tool to evaluate the chemical stability of a cosmetic product under conditions of anticipated use.

  10. Effect of stabilizers on the physico-chemical and sensory attributes ...

    African Journals Online (AJOL)

    SERVER

    2008-01-18

    Jan 18, 2008 ... a source of highly nutritive protein, energy from added cane sugar ... stability of the grain during storage, value of its product and ease of .... Effect of stabilizers on the solids and specific gravity of thermized yoghurt*+. Stabilize.

  11. Imparting chemical stability in nanoparticulate silver via a conjugated polymer casing approach.

    Science.gov (United States)

    Chang, Mincheol; Kim, Taejoon; Park, Hyun-Woo; Kang, Minjeong; Reichmanis, Elsa; Yoon, Hyeonseok

    2012-08-01

    Only limited information is available on the design and synthesis of functional materials for preventing corrosion of metal nanostructures. In the nanometer regime, even noble metals are subject to chemical attack. Here, the corrosion behavior of noble metal nanoparticles coated with a conjugated polymer nanolayer was explored for the first time. Specifically, electrochemical corrosion and sulfur tarnishing behaviors were examined for Ag-polypyrrole (PPy) core-shell nanoparticles using potentiodynamic polarization and spectrophotometric analysis, respectively. First, the Ag-PPy nanoparticles exhibited enhanced resistance to electrochemically induced corrosion compared to their exposed silver counterparts. Briefly, a neutral PPy shell provided the highest protection efficiency (75.5%), followed by sulfate ion- (61.3%) and dodecylbenzenesulfonate ion- (53.6%) doped PPy shells. However, the doping of the PPy shell with chloride ion induced an adverse effect (protection efficiency, -120%). Second, upon exposure to sulfide ions, the Ag-PPy nanoparticles preserved their morphology and colloidal stability while the bare silver analog underwent significant structural deformation. To further understand the function of the PPy shell as a protection layer for the silver core, the catalytic activity of the nanostructures was also evaluated. Using the reduction of 4-nitrophenol as a representative example of a catalytic reaction, the rate constant for that reduction using the PPy encased Ag nanoparticles was found to be 1.1 × 10(-3) s(-1), which is approximately 33% less than that determined for the parent silver. These results demonstrate that PPy can serve as both an electrical and chemical barrier for mitigating undesirable chemical degradation in corrosive environments, as well as provide a simple physical barrier to corrosive substances under appropriate conditions.

  12. Physical and chemical stability of reconstituted and diluted dexrazoxane infusion solutions.

    Science.gov (United States)

    Zhang, Yan-Ping; Myers, Alan L; Trinh, Van A; Kawedia, Jitesh D; Kramer, Mark A; Benjamin, Robert S; Tran, Hai T

    2014-02-01

    Dexrazoxane is used clinically to prevent anthracycline-associated cardiotoxicity. Hydrolysis of dexrazoxane prior to reaching the cardiac membranes severely hampers its mode of action; therefore, degradation during the preparation and administration of intravenous dexrazoxane admixtures demands special attention. Moreover, the ongoing national shortage of one dexrazoxane formulation in the United States has forced pharmacies to dispense other commercially available dexrazoxane products. However, the manufacturers' limited stability data restrict the flexibility of dexrazoxane usage in clinical practice. The aims of this study are to determine the physical and chemical stability of reconstituted and diluted solutions of two commercially available dexrazoxane formulations. The stability of two dexrazoxane products, brand and generic name, in reconstituted and intravenous solutions stored at room temperature without light protection in polyvinyl chloride bags was determined. The concentrations of dexrazoxane were measured at predetermined time points up to 24 h using a validated reversed phase high-performance liquid chromatography with ultraviolet detection assay. Brand (B-) and generic (G-) dexrazoxane products, reconstituted in either sterile water or 0.167 M sodium lactate (final concentration of 10 mg/mL), were found stable for at least to 8 h. Infusion solutions of B-dexrazoxane, prepared according to each manufacturer's directions, were stable for at least 24 h and 8 h at 1 mg/mL and 3 mg/mL, respectively. Infusion solutions of G-dexrazoxane, prepared in either 5% dextrose or 0.9% sodium chloride following the manufacturer's guidelines, were also stable for at least 24 h and 8 h at 1 mg/mL and 3 mg/mL, respectively. All tested solutions were found physically stable up to 24 h at room temperature. The stability of dexrazoxane infusion solutions reported herein permits advance preparation of dexrazoxane intravenous admixtures, facilitating

  13. Evaluation of physical stability and leachability of Portland Pozzolona Cement (PPC) solidified chemical sludge generated from textile wastewater treatment plants

    International Nuclear Information System (INIS)

    Patel, Hema; Pandey, Suneel

    2012-01-01

    Highlights: ► Stabilization/solidification of chemical sludge from textile wastewater treatment plants using Portland Pozzolona Cement (PPC) containing fly ash. ► Physical engineering (compressive strength and block density) indicates that sludge has potential to be reused for construction purpose after stabilization/solidification. ► Leaching of heavy metals from stabilized/solidified materials were within stipulated limits. ► There is a modification of microstructural properties of PPC with sludge addition as indicated by XRD and SEM patterns. - Abstract: The chemical sludge generated from the treatment of textile dyeing wastewater is a hazardous waste as per Indian Hazardous Waste Management rules. In this paper, stabilization/solidification of chemical sludge was carried out to explore its reuse potential in the construction materials. Portland Pozzolona Cement (PPC) was selected as the binder system which is commercially available cement with 10–25% fly ash interground in it. The stabilized/solidified blocks were evaluated in terms of unconfined compressive strength, block density and leaching of heavy metals. The compressive strength (3.62–33.62 MPa) and block density (1222.17–1688.72 kg/m 3 ) values as well as the negligible leaching of heavy metals from the stabilized/solidified blocks indicate that there is a potential of its use for structural and non-structural applications.

  14. Double-Layer Structured CO2 Adsorbent Functionalized with Modified Polyethyleneimine for High Physical and Chemical Stability.

    Science.gov (United States)

    Jeon, Sunbin; Jung, Hyunchul; Kim, Sung Hyun; Lee, Ki Bong

    2018-06-18

    CO 2 capture using polyethyleneimine (PEI)-impregnated silica adsorbents has been receiving a lot of attention. However, the absence of physical stability (evaporation and leaching of amine) and chemical stability (urea formation) of the PEI-impregnated silica adsorbent has been generally established. Therefore, in this study, a double-layer impregnated structure, developed using modified PEI, is newly proposed to enhance the physical and chemical stabilities of the adsorbent. Epoxy-modified PEI and diepoxide-cross-linked PEI were impregnated via a dry impregnation method in the first and second layers, respectively. The physical stability of the double-layer structured adsorbent was noticeably enhanced when compared to the conventional adsorbents with a single layer. In addition to the enhanced physical stability, the result of simulated temperature swing adsorption cycles revealed that the double-layer structured adsorbent presented a high potential working capacity (3.5 mmol/g) and less urea formation under CO 2 -rich regeneration conditions. The enhanced physical and chemical stabilities as well as the high CO 2 working capacity of the double-layer structured adsorbent were mainly attributed to the second layer consisting of diepoxide-cross-linked PEI.

  15. Chemically stabilized reduced graphene oxide/zirconia nanocomposite: synthesis and characterization

    Science.gov (United States)

    Sagadevan, Suresh; Zaman Chowdhury, Zaira; Enamul Hoque, Md; Podder, Jiban

    2017-11-01

    In this research, chemical method was used to fabricate reduced graphene oxide/zirconia (rGO/ZrO2) nanocomposite. X-ray Diffraction analysis (XRD) was carried out to examine the crystalline structure of the nanocomposites. The nanocomposite prepared here has average crystallite size of 14 nm. The surface morphology was observed using scanning electron microscopic analysis (SEM) coupled with electron dispersion spectroscopy (EDS) to detect the chemical element over the surface of the nanocomposites. High-resolution Transmission electron microscopic analysis (HR-TEM) was carried out to determine the particle size and shape of the nanocomposites. The optical property of the prepared samples was determined using UV-visible absorption spectrum. The functional groups were identified using FTIR and Raman spectroscopic analysis. Efficient, cost effective and properly optimized synthesis process of rGO/ZrO2 nanocomposite can ensure the presence of infiltrating graphene network inside the ZrO2 matrix to enhance the electrical properties of the hybrid composites up to a greater scale. Thus the dielectric constant, dielectric loss and AC conductivity of the prepared sample was measured at various frequencies and temperatures. The analytical results obtained here confirmed the homogeneous dispersion of ZrO2 nanostructures over the surface of reduced graphene oxide nanosheets. Overall, the research demonstrated that the rGO/ZrO2 nano-hybrid structure fabricated here can be considered as a promising candidate for applications in nanoelectronics and optoelectronics.

  16. Antifoaming materials studies in G.S. (Girlder sulfide) heavy water plants. Chemical and thermical stability. Pt. 3

    International Nuclear Information System (INIS)

    Delfino, C.A.; Rojo, E.A.

    1988-01-01

    In Girlder sulfide (G.S.) heavy water plants hydrogen sulfide-water systems are inherentely foaming, so the adding of antifoaming materials is of great importance. These may be of high volatility, pyrolizable or chemically unstable in plant operation conditions (water and hydrogen sulfide at 2 MPa, up to 230 deg C). Five commercial surfactants were studied from the point of view of their chemical and thermical stability in order to select the most suitable. (Author) [es

  17. Study on stability of labeled yttrium-90 with lipiodol by chemical extraction for liver cancer

    International Nuclear Information System (INIS)

    Mu, P.Y.; Jiang, X.L.; Chen, J.; Zhu, Y.J.

    2005-01-01

    Liver cancer, particularly hepatocellular carcinoma, is one of the most common malignant diseases in many developed and developing countries. It is also one of the most common diseases endangering the people's lives and health heavily. Surgery is very effective in early-stage patients. Unfortunately, there is less than 10% of the patients with hepatocellular carcinoma fitting for surgical therapy. Instead of surgical therapy, other methods are considered for patients in whom surgery may not work well. Systemic administration of chemotherapeutic agents is not often considered in liver cancer patients, due to discouraging result and adverse side effects. Also, hepatocellular carcinoma is not keen on usual radioactive therapy. However, method of inner interventional radioactive nuclide is a potential way to cure liver tumors. Hepatocellular carcinoma would be cured with inner interventional radioactive nuclide, which is a hot topic in experimental research on hepatocellular carcinoma at home and abroad. The purpose of the study is to label Yttrium-90 with lipiodol by means of the chemical extraction method and research the stability of labeled Yttrium-90 ( 90 Y-P204-Lipiodol) in serum of a newly-born cattle and human's blood. We chose to label steady yttrium with lipiodol, because radioactive yttrium has great nuclear character for liver cancer, yttrium-90 can eradiate pure β radial, and it's half time is 64 hours. Average energy of it is 0.93 Mev, the highest energy is 2.27 Mev. Yttrium-90 can be labeled with lipiodol by means of the chemical extraction method, which is mature in chemical techniques, combined with method of radioactive nuclide labeled in. nuclear medicine. At first, yttrium-90 is extracted in certain condition(pH, temperature, whisk time, whisk frequency, etc ) after adding yttrium-90 solution. We use some distilled water to balance the labeled organic phase twice, and test the stability of labeled yttrium-90 in serum of a newly-born cattle and

  18. Iron-phosphate-based chemically bonded phosphate ceramics for mixed waste stabilization

    International Nuclear Information System (INIS)

    Wagh, A.S.; Jeong, S.Y.; Singh, D.

    1997-01-01

    In an effort to develop chemically bonded phosphate ceramics for mixed waste stabilization, a collaborative project to develop iron-phosphate based ceramics has been initiated between Argonne National Laboratory and the V. G. Khlopin Radium Institute in St. Petersburg, Russia. The starter powders are oxides of iron that are generated as inexpensive byproduct materials in the iron and steel industry. They contain iron oxides as a mixture of magnetite (Fe 3 O 4 ) and haematite (Fe 2 O 3 ). In this initial phase of this project, both of these compounds were investigated independently. Each was reacted with phosphoric acid solution to form iron phosphate ceramics. In the case of magnetite, the reaction was rapid. Adding ash as the waste component containing hazardous contaminants resulted in a dense and hard ceramic rich in glassy phase. On the other hand, the reaction of phosphoric acid solution with a mixture of haematite and ash waste contaminated with cesium and americium was too slow. Samples had to be molded under pressure. They were cured for 2-3 weeks and then hardened by heating at 350 degrees C for 3 h. The resulting ceramics in both cases were subjected to physical tests for measurement of density, open porosity, compression strength, phase analyses using X-ray diffraction and differential thermal analysis, and leaching tests using toxicity characteristic leaching procedure (TCLP) and ANS 16.1 with 7 days of leaching. Using the preliminary information obtained from these tests, we evaluated these materials for stabilization of Department of Energy's mixed waste streams

  19. Chemical stability of insulin. 1. Hydrolytic degradation during storage of pharmaceutical preparations.

    Science.gov (United States)

    Brange, J; Langkjaer, L; Havelund, S; Vølund, A

    1992-06-01

    Hydrolysis of insulin has been studied during storage of various preparations at different temperatures. Insulin deteriorates rapidly in acid solutions due to extensive deamidation at residue AsnA21. In neutral formulations deamidation takes place at residue AsnB3 at a substantially reduced rate under formation of a mixture of isoAsp and Asp derivatives. The rate of hydrolysis at B3 is independent of the strength of the preparation, and in most cases the species of insulin, but varies with storage temperature and formulation. Total transformation at B3 is considerably reduced when insulin is in the crystalline as compared to the amorphous or soluble state, indicating that formation of the rate-limiting cyclic imide decreases when the flexibility of the tertiary structure is reduced. Neutral solutions containing phenol showed reduced deamidation probably because of a stabilizing effect of phenol on the tertiary structure (alpha-helix formation) around the deamidating residue, resulting in a reduced probability for formation of the intermediate imide. The ratio of isoAsp/Asp derivative was independent of time and temperature, suggesting a pathway involving only intermediate imide formation, without any direct side-chain hydrolysis. However, increasing formation of Asp relative to isoAsp derivative was observed with decreasing flexibility of the insulin three-dimensional structure in the formulation. In certain crystalline suspensions a cleavage of the peptide bond A8-A9 was observed. Formation of this split product is species dependent: bovine greater than porcine greater than human insulin. The hydrolytic cleavage of the peptide backbone takes place only in preparations containing rhombohedral crystals in addition to free zinc ions.

  20. Chemical de-conjugation for investigating the stability of small molecule drugs in antibody-drug conjugates.

    Science.gov (United States)

    Chen, Tao; Su, Dian; Gruenhagen, Jason; Gu, Christine; Li, Yi; Yehl, Peter; Chetwyn, Nik P; Medley, Colin D

    2016-01-05

    Antibody-drug conjugates (ADCs) offer new therapeutic options for advanced cancer patients through precision killing with fewer side effects. The stability and efficacy of ADCs are closely related, emphasizing the urgency and importance of gaining a comprehensive understanding of ADC stability. In this work, a chemical de-conjugation approach was developed to investigate the in-situ stability of the small molecule drug while it is conjugated to the antibody. This method involves chemical-mediated release of the small molecule drug from the ADC and subsequent characterization of the released small molecule drug by HPLC. The feasibility of this technique was demonstrated utilizing a model ADC containing a disulfide linker that is sensitive to the reducing environment within cancer cells. Five reducing agents were screened for use in de-conjugation; tris(2-carboxyethyl) phosphine (TCEP) was selected for further optimization due to its high efficiency and clean impurity profile. The optimized de-conjugation assay was shown to have excellent specificity and precision. More importantly, it was shown to be stability indicating, enabling the identification and quantification of the small molecule drug and its degradation products under different formulation pHs and storage temperatures. In summary, the chemical de-conjugation strategy demonstrated here offers a powerful tool to assess the in-situ stability of small molecule drugs on ADCs and the resulting information will shed light on ADC formulation/process development and storage condition selection. Copyright © 2015 Elsevier B.V. All rights reserved.

  1. A review of the chemical and physical mechanisms of the storage stability of fast pyrolysis bio-oils

    Energy Technology Data Exchange (ETDEWEB)

    Diebold, J.P.

    1999-01-27

    Understanding the fundamental chemical and physical aging mechanisms is necessary to learn how to produce a bio-oil that is more stable during shipping and storage. This review provides a basis for this understanding and identifies possible future research paths to produce bio-oils with better storage stability.

  2. Comparative leaching of six toxic metals from raw and chemically stabilized MSWI fly ash using citric acid.

    Science.gov (United States)

    Wang, Huawei; Fan, Xinxiu; Wang, Ya-Nan; Li, Weihua; Sun, Yingjie; Zhan, Meili; Wu, Guizhi

    2018-02-15

    The leaching behavior of six typical toxic metals (Pb, Zn, Cr, Cd, Cu and Ni) from raw and chemically stabilized (phosphate and chelating agent) municipal solid waste incineration (MSWI) fly ash were investigated using citric acid. Leaching tests indicated that phosphate stabilization can effectively decrease the leaching of Zn, Cd and Cr; whereas chelating agent stabilization shows a strong ability to lower the release of Pb, Cd and Cu, but instead increases the solubility of Zn and Cr at low pH conditions. Sequential extraction results suggested that the leaching of Pb, Zn and Cd in both the stabilized MSWI fly ash samples led to the decrease in Fe/Mn oxide fraction and the increase in exchangeable and carbonate fractions. The leaching of Cr was due to the decrease in exchangeable, carbonate and Fe/Mn oxide fractions in phosphate-stabilized and chelating agent-stabilized MSWI fly ash. The leaching of Cu in both stabilized MSWI fly ash was greatly ascribed to the decrease in Fe/Mn oxide and oxidisable fractions. Moreover, predicted curves by geochemical model indicated that both stabilized MSWI fly ash have the risk of releasing toxic metals under strong acid environment. Copyright © 2017 Elsevier Ltd. All rights reserved.

  3. The Influence of Chemically Modified Potato Maltodextrins on Stability and Rheological Properties of Model Oil-in-Water Emulsions

    Directory of Open Access Journals (Sweden)

    Karolina Pycia

    2018-01-01

    Full Text Available The aim of this study was to determine the effect of the maltodextrins prepared from chemically modified starches (crosslinked, stabilized, crosslinked and stabilized on the stability and rheological properties of model oil-in-water (o/w emulsions. Based on the obtained results, it was concluded that emulsion stability depended on hydrolysates dextrose equivalent (DE value. Maltodextrin with the lowest degree of depolymerization effectively stabilized the dispersed system, and the effectiveness of this action depended on the maltodextrin type and concentration. Addition of distarch phosphate-based maltodextrin stabilized emulsion at the lowest applied concentration, and the least effective was maltodextrin prepared from acetylated starch. Emulsions stabilized by maltodextrins (DE 6 prepared from distarch phosphate and acetylated distarch adipate showed the predominance of the elastic properties over the viscous ones. Only emulsion stabilized by maltodextrin prepared from distarch phosphate (E1412 revealed the properties of strong gel. Additionally, the decrease in emulsions G′ and G″ moduli values, combined with an increase in the value of DE maltodextrins, was observed.

  4. Chemical stability and in chemico reactivity of 24 fragrance ingredients of concern for skin sensitization risk assessment.

    Science.gov (United States)

    Avonto, Cristina; Wang, Mei; Chittiboyina, Amar G; Vukmanovic, Stanislav; Khan, Ikhlas A

    2018-02-01

    Twenty-four pure fragrance ingredients have been identified as potential concern for skin sensitization. Several of these compounds are chemically unstable and convert into reactive species upon exposure to air or light. In the present work, a systematic investigation of the correlation between chemical stability and reactivity has been undertaken. The compounds were subjected to forced photodegradation for three months and the chemical changes were studied with GC-MS. At the end of the stability study, two-thirds of the samples were found to be unstable. The generation of chemically reactive species was investigated using the in chemico HTS-DCYA assay. Eleven and fourteen compounds were chemically reactive before and after three months, respectively. A significant increase in reactivity upon degradation was found for isoeugenol, linalool, limonene, lyral, citronellol and geraniol; in the same conditions, the reactivity of hydroxycitronellal decreased. The non-reactive compounds α-isomethyl ionone, benzyl alcohol, amyl cinnamal and farnesol became reactive after photo-oxidative degradation. Overall, forced degradation resulted in four non-reactive fragrance compounds to display in chemico thiol reactivity, while ten out of 24 compounds remained inactive. Chemical degradation does not necessarily occur with generation of reactive species. Non-chemical activation may be involved for the 10 stable unreactive compounds. Copyright © 2017 Elsevier Ltd. All rights reserved.

  5. Chemical stabilization of cadmium in acidic soil using alkaline agronomic and industrial by-products.

    Science.gov (United States)

    Chang, Yao-Tsung; Hsi, Hsing-Cheng; Hseu, Zeng-Yei; Jheng, Shao-Liang

    2013-01-01

    In situ immobilization of heavy metals using reactive or stabilizing materials is a promising solution for soil remediation. Therefore, four agronomic and industrial by-products [wood biochar (WB), crushed oyster shell (OS), blast furnace slag (BFS), and fluidized-bed crystallized calcium (FBCC)] and CaCO3 were added to acidic soil (Cd = 8.71 mg kg(-1)) at the rates of 1%, 2%, and 4% and incubated for 90 d. Chinese cabbage (Brassica chinensis L.) was then planted in the soil to test the Cd uptake. The elevation in soil pH caused by adding the by-products produced a negative charge on the soil surface, which enhanced Cd adsorption. Consequently, the diethylenetriamine pentaacetic acid (DTPA)-extractable Cd content decreased significantly (P soil. These results from the sequential extraction procedure indicated that Cd converted from the exchangeable fraction to the carbonate or Fe-Mn oxide fraction. The long-term effectiveness of Cd immobilization caused by applying the 4 by-products was much greater than that caused by applying CaCO3. Plant shoot biomass clearly increased because of the by-product soil amendment. Cd concentration in the shoots was soil.

  6. Influence of N-Oxide Introduction on the Stability of Nitrogen-Rich Heteroaromatic Rings: A Quantum Chemical Study.

    Science.gov (United States)

    Yuan, Jia; Long, Xinping; Zhang, Chaoyang

    2016-12-01

    N-Oxidization is an important strategy for enhancing the density and energy of energetic materials. Nevertheless, the influence of N + -O - introduction on molecular stability remains relatively unknown. Thus, the present work comprehensively studied 102 basic N-rich ring structures, including azoles, furazans, and azines, as well as their N-oxides by quantum chemical calculations. The introduction of N + -O - weakens molecular stability in most cases because the process elongates chemical bonds, decreases ring aromaticity, narrows the gaps between the highest occupied and lowest unoccupied molecular orbitals, and increases the photochemical reactivity. Besides, the easy H transfer to the neighboring O atom, which forms a N-OH isomer in azoles, renders the stabilization by N-oxide introduction ineffective. However, N-oxide introduction can enhance the molecular stability of 1,2,3,4-tetrazine-1,3-dioxide and tetrazino-tetrazine 1,3,6,8-tetraoxide by promoting σ-π separation and relieving lone-pair repulsion. Moreover, the alternate arrangement of positive and negative charges is another factor stabilizing the 1,2,3,4-tetrazine ring by 1,3-dioxidation. Finally, we assess the accessibility of N-oxidized azoles and azines by regarding N 2 O and H 2 O 2 as oxidizers. We find that all the oxidations were exothermic, thermodynamically spontaneous, and kinetically feasible. After an overall evaluation, we propose 19 N-oxides as basic structures for high-energy materials with considerable stability.

  7. Physical and chemical stability of expired fixed dose combination artemether-lumefantrine in uncontrolled tropical conditions

    Directory of Open Access Journals (Sweden)

    Hess Kimberly

    2009-02-01

    Full Text Available Abstract Background New artemisinin combination therapies pose difficulties of implementation in developing and tropical settings because they have a short shelf-life (two years relative to the medicines they replace. This limits the reliability and cost of treatment, and the acceptability of this treatment to health care workers. A multi-pronged investigation was made into the chemical and physical stability of fixed dose combination artemether-lumefantrine (FDC-ALU stored under heterogeneous, uncontrolled African conditions, to probe if a shelf-life extension might be possible. Methods Seventy samples of expired FDC-ALU were collected from private pharmacies and malaria researchers in seven African countries. The samples were subjected to thin-layer chromatography (TLC, disintegration testing, and near infrared Raman spectrometry for ascertainment of active ingredients, tablet integrity, and chemical degradation of the tablet formulation including both active ingredients and excipients. Results Seventy samples of FDC-ALU were tested in July 2008, between one and 58 months post-expiry. 68 of 70 (97% samples passed TLC, disintegration and Raman spectrometry testing, including eight samples that were post-expiry by 20 months or longer. A weak linear association (R2 = 0.33 was observed between the age of samples and their state of degradation relative to brand-identical samples on Raman spectrometry. Sixty-eight samples were retested in February 2009 using Raman spectrometry, between eight and 65 months post-expiry. 66 of 68 (97% samples passed Raman spectrometry retesting. An unexpected observation about African drug logistics was made in three batches of FDC-ALU, which had been sold into the public sector at concessional pricing in accordance with a World Health Organization (WHO agreement, and which were illegally diverted to the private sector where they were sold for profit. Conclusion The data indicate that FDC-ALU is chemically and

  8. Nutritional Profile and Chemical Stability of Pasta Fortified with Tilapia (Oreochromis niloticus) Flour.

    Science.gov (United States)

    Monteiro, Maria Lúcia G; Mársico, Eliane T; Soares, Manoel S; Magalhães, Amanda O; Canto, Anna Carolina V C S; Costa-Lima, Bruno R C; Alvares, Thiago S; Conte, Carlos A

    2016-01-01

    Physicochemical parameters of pasta enriched with tilapia (Oreochromis niloticus) flour were investigated. Five formulations were prepared with different concentrations of tilapia flour as partial substitute of wheat flour: pasta without tilapia flour (PTF0%), pasta with 6% (PTF6%), 12% (PTF12%), 17% (PTF17%), and 23% (PTF23%) of tilapia flour. The formulations were assessed for proximate composition, fatty acid and amino acid profile on day 1 whereas, instrumental color parameters (L*, a* and b* values), pH, water activity (aw), and lipid and protein oxidation were evaluated on days 1, 7, 14, and 21 of storage at 25°C. Fortification with tilapia flour increased (p pasta with tilapia flour decreased (p pasta containing 12%, 17%, and 23% of tilapia flour than their counterparts, and the storage promoted an increase (p pasta with 6% of tilapia flour has the potential to be a technological alternative to food industry for the nutritional enrichment of traditional pasta with negligible negative effects on the chemical stability of the final product during 21 days at 25°C.

  9. Energetics and stability of azulene: From experimental thermochemistry to high-level quantum chemical calculations

    International Nuclear Information System (INIS)

    Sousa, Clara C.S.; Matos, M. Agostinha R.; Morais, Victor M.F.

    2014-01-01

    Highlights: • Experimental standard molar enthalpy of formation, sublimation azulene. • Mini-bomb combustion calorimetry, sublimation Calvet microcalorimetry. • High level composite ab initio calculations. • Computational estimate of the enthalpy of formation of azulene. • Discussion of stability and aromaticity of azulene. - Abstract: The standard (p 0 = 0.1 MPa) molar enthalpy of formation for crystalline azulene was derived from the standard molar enthalpy of combustion, in oxygen, at T = 298.15 K, measured in a mini-bomb combustion calorimeter (aneroid isoperibol calorimeter) and the standard molar enthalpy of sublimation, at T = 298.15 K, measured by Calvet microcalorimetry. From these experiments, the standard molar enthalpy of formation of azulene in the gaseous phase at T = 298.15 K was calculated. In addition, very accurate quantum chemical calculations at the G3 and G4 composite levels of calculation were conducted in order to corroborate our experimental findings and further clarify and establish the definitive standard enthalpy of formation of this interesting non-benzenoid hydrocarbon

  10. Arsenic stability and mobilization in soil at an amenity grassland overlying chemical waste (St. Helens, UK)

    Energy Technology Data Exchange (ETDEWEB)

    Hartley, William [School of Biological and Earth Sciences, Liverpool John Moores University, Byrom Street, Liverpool L3 3AF (United Kingdom)], E-mail: w.hartley@ljmu.ac.uk; Dickinson, Nicholas M. [School of Biological and Earth Sciences, Liverpool John Moores University, Byrom Street, Liverpool L3 3AF (United Kingdom); Clemente, Rafael [Department of Soil and Water Conservation and Organic Waste Management, Centro de Edafologia y Biologia Aplicada del Segura, CSIC, Apartado 4195, 30080 Murcia (Spain); French, Christopher [School of Biological and Earth Sciences, Liverpool John Moores University, Byrom Street, Liverpool L3 3AF (United Kingdom); Piearce, Trevor G. [Biological Sciences Division, Lancaster Environment Centre, Lancaster University, Lancaster LA1 4YQ (United Kingdom); Sparke, Shaun; Lepp, Nicholas W. [School of Biological and Earth Sciences, Liverpool John Moores University, Byrom Street, Liverpool L3 3AF (United Kingdom)

    2009-03-15

    A 6.6 ha grassland, established on a former chemical waste site adjacent to a residential area, contains arsenic (As) in surface soil at concentrations 200 times higher than UK Soil Guideline Values. The site is not recognized as statutory contaminated land, partly on the assumption that mobility of the metalloid presents a negligible threat to human health, groundwater and ecological receptors. Evidence for this is evaluated, based on studies of the effect of organic (green waste compost) and inorganic (iron oxides, lime and phosphate) amendments on As fractionation, mobility, plant uptake and earthworm communities. Arsenic mobility in soil was low but significantly related to dissolved organic matter and phosphate, with immobilization associated with iron oxides. Plant uptake was low and there was little apparent impact on earthworms. The existing vegetation cover reduces re-entrainment of dust-blown particulates and pathways of As exposure via this route. Minimizing risks to receptors requires avoidance of soil exposure, and no compost or phosphate application. - Stabilization of alkali industry waste requires careful management to minimise soil arsenic mobilization and dispersal to the wider environment.

  11. A conceptual chemical solidification/stabilization system to remediate radioactive raffinate sludge

    International Nuclear Information System (INIS)

    Carpenter, D.J.; Ansted, J.P.; Foldyna, J.T.

    1994-01-01

    Past operations at the U.S. Department of Energy's (DOE) Weldon Spring, Missouri, Superfund Site included the manufacture of nitroaromatic-based munitions and the production of uranium and thorium metal from ore concentrates. These operations generated a large quantity of diverse contaminated waste media including raffinate sludge, soil, sediment, and building debris. These various waste media are contaminated with varying amounts of radionuclides nitroaromatics, metals, metalloids, non-metals, polychlorinated biphenyls (PCBs) and asbestos. The volumes and diversity of contaminants and waste media pose significant challenges in identifying applicable remedial technologies, particularly for the excavation and treatment of the water-rich raffinate sludge. This paper presents the results of comprehensive efforts to develop a conceptual chemical solidification/stabilization (CSS) system to treat a variety of waste media. The emphasis of this paper is the treatment of a water-rich refractory raffinate sludge and site contaminated soils both radioactive and nonradioactive. The conceptual system design includes raffinate sludge excavation, dewatering, and CSS processing (reagent selection and formulation, reagent and waste storage and metering, and product mixing). Many innovations were incorporated into the design, producing a system that can process the various waste types. Additionally, the radioactive and hazardous constituents are sufficiently immobilized to allow the secured disposal in a waste cell of the treated product. The conceptual CSS system can also produce a variety of treated product types, ranging from a monolithic form to a compactible soil-like medium. The advantages of this system flexibility are also presented

  12. Physico-chemical and mineralogical properties influencing water-stability of aggregates of some Italian surface soils

    International Nuclear Information System (INIS)

    Mbagwu, J.S.C.; Bazzoffi, P.; Unamba Oparah, I.

    1994-06-01

    A laboratory study was conducted to determine the relationship between physical, chemical and mineralogical properties of some surface soils (developed in north central Italy) and the stability of their aggregates to water. The index of stability used is the mean-weight diameter of water-stable aggregates (MWD). The ratio of total sand to clay which correlated negatively with MWD (r=-0.638) is the physical property which explained most of the variability in aggregate stability. The chemical properties which correlated best with aggregate stability are FeO (r=0.671), CaO (R=0.635), CaCO 3 (r=0.651) and SiO 2 (r=-0.649). Feldspar, chlorite and calcite are the minerals which influence MWD most, with respective ''r'' values of -0.627, 0.588 and 0.550. The best-fit model developed from soil physical properties explained 59% of the variation in MWD with a standard error of 0.432, that developed from chemical properties explained 97% of the variation in MWD with a standard error of 0.136, whereas the model developed from mineralogical properties explained 78% of the variation in MWD with a standard error of 0.222. Also the closest relationship between measured and model-predicted MWD was obtained with the chemical properties-based model (r=0.985), followed by the mineralogical properties-based model (r=0.884) and then the physical properties-based model (r=0.656). This indicates that the most reliable inference on the stability of these soils in water can be made from a knowledge of the amount and composition of their chemical constituents. (author). 32 refs, 1 fig., 9 tabs

  13. Radiation and chemical stability of 2-deoxy-2-[18F]fluoro-D-glucose radiopharmaceutical

    International Nuclear Information System (INIS)

    Buriova, M.

    2004-07-01

    molecules association with formate anion HCOO - and also for negative ions of deprotonised molecules. All acids appeared in the form of their lactones. FDG and GLC exhibited tendency for formation of a mixed associate charged by HCOO - anion. On the amine bond silica gel HPTLC column, FDG is poorly separated from fluoride, which even in presence of Kryptofix 2.2.2 remains on the start like on the silica gel layer. The last parathion is to be used as a standard technique for [ 18 F]F - assay. At LC-MS Kryptofix provides a very well measurable signals of associates with NH 4 + a H + ions in positive mode of ESI MS. Sensitivity of the ESI MS detector towards sugars is for three orders of magnitude higher than the refraction index detector, which is used for routine analysis, and enables estimation of molar activity of non-carrier-added 2-[ 18 F]FDG. The results of quantitative LC/MS analysis and high-efficient radiometric detector were used for specific activity of 2-[ 18 F]FDG assessment. Concentration of FDG carrier in 2-[ 18 F]FDG preparation was found to be 6 mg.dm -3 and in combination with a radiometric detector the specific activity 6.6 GBq.μmol -1 of 2-[ 18 F]FDG was found. The molar activity of carrier-free ( 18 F)FDG is 63 TBq.μmol -1 , and for good quality of bio-specific ligands at PET it is supposed to be minimally 1 kBq.fmol -1 . Radiation and chemical stability of 2-deoxy-2-[ 18 F]fluoro-D-glucose, and its comparison with glucose at oxidation by Fenton's reagent and autoradiolysis was found. The main oxidation products of FDG and glucose by Fenton's reagent were arabonic acid at 14-23% yield, gluconic acid 12%, both glucuronic acid and arabinose at 5%. In case of FDG among the principal products 2-fluorgluconic acid and 2-fluorgluconic acid by 2.7 % and 4% yields respectively were identified. The dose rates in real solutions of 2-[ 18 F]FDG, as well as the radiation-chemical yields of radioactive (fluorinated), but also further products of autoradiolysis of 2

  14. Chemical modification with phthalic anhydride and chitosan: Viable options for the stabilization of raw starch digesting amylase from Aspergillus carbonarius.

    Science.gov (United States)

    Nwagu, Tochukwu Nwamaka; Okolo, Bartholomew; Aoyagi, Hideki; Yoshida, Shigeki

    2017-06-01

    The raw starch digesting type of amylase (RSDA) presents greater opportunities for process efficiency at cheaper cost and shorter time compared to regular amylases. Chemical modification is a simple and rapid method toward their stabilization for a wider application. RSDA from Aspergillus carbonarius was modified with either phthalic anhydride (PA) or chitosan. Activity retention was 87.3% for PA-modified and 80.9% for chitosan-modified RSDA. Optimum pH shifted from 5 to 7 after PA-modification. Optimum temperature changed from 30°C (native) to 30-40°C and 60°C for PA-modified and chitosan-modified, respectively. Activation energy (kJmol -1 ) for hydrolysis was 13.5, 12.7, and 10.2 while the activation energy for thermal denaturation was 32.8, 80.3, 81.9 for free, PA-modified and chitosan-modified, respectively. The specificity constants (V max /K m ) were 73.2 for PA-modified, 63.1 for chitosan-modified and 77.1 for native RSDA. The half-life (h) of the RSDA at 80°C was increased from 6.1 to 25.7 for the PA-modified and 138.6 for the chitosan derivative. Modification also led to increase in D value, activation enthalpy and Gibbs free energy of enzyme deactivation. Fluorescence spectra showed that center of spectral mass decreased for the PA-modified RSDA but increased for chitosan modified RSDA. Copyright © 2017 Elsevier B.V. All rights reserved.

  15. More features, greater connectivity.

    Science.gov (United States)

    Hunt, Sarah

    2015-09-01

    Changes in our political infrastructure, the continuing frailties of our economy, and a stark growth in population, have greatly impacted upon the perceived stability of the NHS. Healthcare teams have had to adapt to these changes, and so too have the technologies upon which they rely to deliver first-class patient care. Here Sarah Hunt, marketing co-ordinator at Aid Call, assesses how the changing healthcare environment has affected one of its fundamental technologies - the nurse call system, argues the case for wireless such systems in terms of what the company claims is greater adaptability to changing needs, and considers the ever-wider range of features and functions available from today's nurse call equipment, particularly via connectivity with both mobile devices, and ancillaries ranging from enuresis sensors to staff attack alert 'badges'.

  16. The pH-dependent long-term stability of an amorphous manganese oxide in smelter-polluted soils: implication for chemical stabilization of metals and metalloids.

    Science.gov (United States)

    Ettler, Vojtěch; Tomášová, Zdeňka; Komárek, Michael; Mihaljevič, Martin; Šebek, Ondřej; Michálková, Zuzana

    2015-04-09

    An amorphous manganese oxide (AMO) and a Pb smelter-polluted agricultural soil amended with the AMO and incubated for 2 and 6 months were subjected to a pH-static leaching procedure (pH 3-8) to verify the chemical stabilization effect on metals and metalloids. The AMO stability in pure water was pH-dependent with the highest Mn release at pH 3 (47% dissolved) and the lowest at pH 8 (0.14% dissolved). Secondary rhodochrosite (MnCO3) was formed at the AMO surfaces at pH>5. The AMO dissolved significantly less after 6 months of incubation. Sequential extraction analysis indicated that "labile" fraction of As, Pb and Sb in soil significantly decreased after AMO amendment. The pH-static experiments indicated that no effect on leaching was observed for Cd and Zn after AMO treatments, whereas the leaching of As, Cu, Pb and Sb decreased down to 20%, 35%, 7% and 11% of the control, respectively. The remediation efficiency was more pronounced under acidic conditions and the time of incubation generally led to increased retention of the targeted contaminants. The AMO was found to be a promising agent for the chemical stabilization of polluted soils. Copyright © 2015 Elsevier B.V. All rights reserved.

  17. Physical and chemical stability of palonosetron hydrochloride with dacarbazine and with methylprednisolone sodium succinate during simulated y-site administration.

    Science.gov (United States)

    Trissel, Lawrence A; Zhang, Yanping; Xu, Quanyun A

    2006-01-01

    The objective of this study was to evaluate the physical and chemical stability of mixtures of undiluted palonosetron hydrochloride 50 micrograms/mL with dacarbazine 4 mg/mL and with methylprednisolone sodium succinate 5 mg/mL in 5% dextrose injection during simulated Y-site administration. Triplicate test samples were prepared by admixing 7.5 mL of palonosetron hydrochloride with 7.5 mL of dacarbazine solution and, separately, methylprednisolone sodium succinate solution. Physical stability was assessed by using a multistep evaluation procedure that included both turbidimetric and particulate measurement as well as visual inspection. Chemical stability was assessed by using stability-indicating high-performance liquid chromatographic analytical techniques that determined drug concentrations. Evaluations were performed immediately after mixing and 1 and 4 hours after mixing. The palonosetron hydrochloride-dacarbazine samples were clear and colorless when viewed in normal fluorescent room light and when viewed with a Tyndall beam. Measured turbidities remained unchanged; particulate contents were low and exhibited little change. High-performance liquid chromatography analysis revealed that palonosetron hydrochloride and dacarbazine remained stable throughout the 4-hour test with no drug loss. Palonosetron hydrochloride is, therefore, physically compatible and chemically stable with dacarbazine during Y-site administration. Within 4 hours, the mixtures of palonosetron hydrochloride and methylprednisolone sodium succinate developed a microprecipitate that became a white precipitate visible to the unaided eye. The precipitate was analyzed and identified as methylprednisolone. Palonosetron hydrochloride is incompatible with methylprednisolone sodium succinate.

  18. Stabilization

    Directory of Open Access Journals (Sweden)

    Muhammad H. Al-Malack

    2016-07-01

    Full Text Available Fuel oil flyash (FFA produced in power and water desalination plants firing crude oils in the Kingdom of Saudi Arabia is being disposed in landfills, which increases the burden on the environment, therefore, FFA utilization must be encouraged. In the current research, the effect of adding FFA on the engineering properties of two indigenous soils, namely sand and marl, was investigated. FFA was added at concentrations of 5%, 10% and 15% to both soils with and without the addition of Portland cement. Mixtures of the stabilized soils were thoroughly evaluated using compaction, California Bearing Ratio (CBR, unconfined compressive strength (USC and durability tests. Results of these tests indicated that stabilized sand mixtures could not attain the ACI strength requirements. However, marl was found to satisfy the ACI strength requirement when only 5% of FFA was added together with 5% of cement. When the FFA was increased to 10% and 15%, the mixture’s strength was found to decrease to values below the ACI requirements. Results of the Toxicity Characteristics Leaching Procedure (TCLP, which was performed on samples that passed the ACI requirements, indicated that FFA must be cautiously used in soil stabilization.

  19. Application of a high-throughput relative chemical stability assay to screen therapeutic protein formulations by assessment of conformational stability and correlation to aggregation propensity.

    Science.gov (United States)

    Rizzo, Joseph M; Shi, Shuai; Li, Yunsong; Semple, Andrew; Esposito, Jessica J; Yu, Shenjiang; Richardson, Daisy; Antochshuk, Valentyn; Shameem, Mohammed

    2015-05-01

    In this study, an automated high-throughput relative chemical stability (RCS) assay was developed in which various therapeutic proteins were assessed to determine stability based on the resistance to denaturation post introduction to a chaotrope titration. Detection mechanisms of both intrinsic fluorescence and near UV circular dichroism (near-UV CD) are demonstrated. Assay robustness was investigated by comparing multiple independent assays and achieving r(2) values >0.95 for curve overlays. The complete reversibility of the assay was demonstrated by intrinsic fluorescence, near-UV CD, and biologic potency. To highlight the method utility, we compared the RCS assay with differential scanning calorimetry and dynamic scanning fluorimetry methodologies. Utilizing C1/2 values obtained from the RCS assay, formulation rank-ordering of 12 different mAb formulations was performed. The prediction of long-term stability on protein aggregation is obtained by demonstrating a good correlation with an r(2) of 0.83 between RCS and empirical aggregation propensity data. RCS promises to be an extremely useful tool to aid in candidate formulation development efforts based on the complete reversibility of the method to allow for multiple assessments without protein loss and the strong correlation between the C1/2 data obtained and accelerated stability under stressed conditions. © 2015 Wiley Periodicals, Inc. and the American Pharmacists Association.

  20. Assessing the physical-chemical properties and stability of dapivirine-loaded polymeric nanoparticles.

    Science.gov (United States)

    das Neves, José; Amiji, Mansoor; Bahia, Maria Fernanda; Sarmento, Bruno

    2013-11-18

    Nanocarriers may provide interesting delivery platforms for microbicide drugs and their characterization should be addressed early in development. Differently surface-engineered dapivirine-loaded, poly(epsilon-caprolactone) (PCL)-based nanoparticles (NPs) were obtained by nanoprecipitation using polyethylene oxide (PEO), sodium lauryl sulfate (SLS), or cetyltrimethylammonium bromide (CTAB) as surface modifiers. Physical-chemical properties of NP aqueous dispersions were evaluated upon storage at -20-40 °C for one year. NPs presented 170-200 nm in diameter, roundish-shape, low polydispersity index (≤0.18), and high drug association efficiency (≥97%) and loading (≥12.7%). NPs differed in zeta potential, depending on surface modifier (PEO: -27.9 mV; SLS: -54.7 mV; CTAB: +42.4 mV). No interactions among formulation components were detected by differential scanning calorimetry (DSC) and Fourier transform infrared spectroscopy (FTIR), except for SLS-PCL NPs. Colloidal properties of NPs were lost at -20 °C storage. Negatively charged NPs were stable up to one year at 5-40°C; as for CTAB-PCL NPs, particle aggregation was observed from 30 to 90 days of storage depending on temperature. Colloidal instability affected the in vitro drug release of CTAB-PCL NPs after 360 days. In any case, no degradation of dapivirine was apparent. Overall, PEO-PCL and SLS-PCL NPs presented suitable properties as nanocarriers for dapivirine. Conversely, CTAB-PCL NPs require additional strategies in order to increase stability. Copyright © 2013 Elsevier B.V. All rights reserved.

  1. Achieving synergy between chemical oxidation and stabilization in a contaminated soil.

    Science.gov (United States)

    Srivastava, Vipul J; Hudson, Jeffrey Michael; Cassidy, Daniel P

    2016-07-01

    Eight in situ solidification/stabilization (ISS) amendments were tested to promote in situ chemical oxidation (ISCO) with activated persulfate (PS) in a contaminated soil. A 3% (by weight) dose of all ISS amendments selected for this study completely activated a 1.5% dose of PS within 3 h by raising temperatures above 30 °C (heat activation) and/or increasing pH above 10.5 (alkaline activation). Heat is released by the reaction of CaO with water, and pH increases because this reaction produces Ca(OH)2. Heat activation is preferred because it generates 2 mol of oxidizing radicals per mole of PS, whereas alkaline activation releases only 1. The relative contribution of heat vs. alkaline activation increased with CaO content of the ISS amendment, which was reflected by enhanced contaminant oxidation with increasing CaO content, and was confirmed by comparing to controls promoting purely heat or alkaline (NaOH) activation. The test soil was contaminated with benzene, toluene, ethylbenzene, and xylenes (BTEX) and polycyclic aromatic hydrocarbons (PAH), particularly naphthalene (NAP). ISS-activated PS oxidized between 47% and 84% of the BTEX & NAP, and between 13% and 33% of the higher molecular weight PAH. ISS-activated PS reduced the leachability of BTEX & NAP by 76%-91% and of the 17 PAH by 83%-96%. Combined ISCO/ISS reduced contaminant leachability far than ISCO or ISS treatments alone, demonstrating the synergy that is possible with combined remedies. Copyright © 2016 Elsevier Ltd. All rights reserved.

  2. Chemical cross-linked polyvinyl alcohol/cellulose nanocrystal composite films with high structural stability by spraying Fenton reagent as initiator.

    Science.gov (United States)

    Song, Meili; Yu, Houyong; Gu, Jiping; Ye, Shounuan; Zhou, Yuwei

    2018-07-01

    Cross-linked polyvinyl alcohol (PVA) composite films with high structural stability were prepared by free radical copolymerization between cellulose nanocrystal (CNC) and maleic anhydride (MAH) modified PVA through spraying Fenton free radical as initiator. The influence of chemical cross-linked and physical network structure on mechanical, thermal and water absorption properties of the composite films were investigated. Compared to PVA and PVA/CNC composite film, significant improvements in the mechanical, thermal and water uptake properties of the cross-linked composite film were found. The tensile strength of the cross-linked composite film was enhanced from 23.1MPa (neat PVA film) and 32.6MPa (PVA/CNC-10%) to 42.5MPa, and the maximum thermal degradation temperature was increased from 266.8°C and 281.2°C to 366.7°C (cross-linked composite film). Besides, the water absorption was reduced from 385.9% and 220.6% to 175.7% for cross-linked composite film. It indicates that compared with physical network structure in PVA/CNC composite film, the multiple cross-linked networks showed excellent thermal stability, resistance of water swelling and structural stability at the same CNC loading level. Thus, the PVA/CNC composite film with the multiple cross-linked network shows greater property reinforcements. Copyright © 2018 Elsevier B.V. All rights reserved.

  3. Physico-chemical, antioxidant, and anti-inflammatory properties and stability of hawthorn (Crataegus monogyna Jacq.) procyanidins microcapsules with inulin and maltodextrin.

    Science.gov (United States)

    Wyspiańska, Dorota; Kucharska, Alicja Z; Sokół-Łętowska, Anna; Kolniak-Ostek, Joanna

    2017-01-01

    Procyanidins from the bark of hawthorn (Crataegus monogyna Jacq.) were isolated and purified. Qualitative and quantitative composition was compared with that of the extract of hawthorn fruit (Crataegus monogyna Jacq.). Stability and antioxidant and anti-inflammatory properties of procyanidins before and after micro-encapsulation were estimated. The effects of the carrier type (inulin and maltodextrin) and procyanidins:carrier ratio (1:1, 1:3) and the influence of storage temperature (20 °C, -20 °C, -80 °C) on the content of procyanidins were evaluated. Samples before and after micro-encapsulation contained from 651 to 751 mg of procyanidins in 1 g. Among the procyanidins, (-)-epicatechin, dimer B2, and trimer C1 dominated. The use of inulin during spray drying resulted in greater efficiency of micro-encapsulation than the use of maltodextrin. During storage of the samples at 20 °C degradation of procyanidins was observed, whereas at -20 °C and -80 °C concentrations of them increased. The microcapsules with procyanidins from the bark of hawthorn, as well as the extract of procyanidins, have valuable biological activity, and strong antioxidant and anti-inflammatory properties. It is better to prepare microcapsules with a greater amount of carrier, with the procyanidin/carrier ratio 1:3. © 2016 Society of Chemical Industry. © 2016 Society of Chemical Industry.

  4. Oxygen permeation and thermo-chemical stability of oxygen separation membrane materials for the oxyfuel process

    Energy Technology Data Exchange (ETDEWEB)

    Ellett, Anna Judith

    2009-07-01

    analysis (TGA) and thermo mechanical analysis (TMA). An increase in thermal expansion and oxygen permeation associated with an increase in oxygen vacancy concentration, observed also in the TGA curves, occurs during heating. BSCF50 exhibits permeation fluxes well above those of LSCF58, PSCF58 and La{sub 2}NiO{sub 4+{delta}}, which are quite similar to each other. After exposure, no degradation of LSCF58, La{sub 2}NiO{sub 4+{delta}} and PSCF58 occurs. On the other hand BSCF50 is found to be unstable in CO{sub 2}- and/or H{sub 2}O-containing atmospheres and also to exhibit a chemical demixing. The thermo-chemical stability and the oxygen permeation performances are both crucial factors in the selection of high purity oxygen separation membranes for the oxyfuel process, thus making LSCF58, PSCF58 and La{sub 2}NiO{sub 4+{delta}} in this study the most suitable materials for this application. Serious issues arise, however, from the fact that secondary non-ion conducting oxide phases are formed in the bulk of every material, forming obstacles for oxygen ion migration, and also that a reaction with chromia occurs, preventing their use without protection. (orig.)

  5. Understanding chemical-potential-related transient pore-pressure response to improve real-time borehole (in)stability predictions

    Energy Technology Data Exchange (ETDEWEB)

    Tare, U. A.; Mody, F. K.; Mese, A. I. [Haliburton Energy Services, TX (United States)

    2002-07-01

    In order to develop a real-time wellbore (in)stability modelling capability, experimental work was carried out to investigate the role of the chemical potential of drilling fluids on transient pore pressure and time-dependent rock property alterations of shale formations. Time-dependent alterations in the pore pressure, acoustic and rock properties of formations subjected to compressive tri-axial test were recorded during the experiments involving the Pore Pressure Transmission (PPT) test. Based on the transient pore pressure of shale exposed to the test fluid presented here, the 20 per cent calcium chloride showed a very low membrane efficiency of 4.45 per cent. The need for a thorough understanding of the drilling fluid/shale interaction prior to applying any chemical potential wellbore (in)stability model to real-time drilling operations was emphasized. 9 refs., 5 figs.

  6. PHYSICAL AND CHEMICAL STABILITY ANALYSIS OF COSMETIC MULTI- PLE EMULSIONS LOADED WITH ASCORBYL PALMITATE AND SODIUM ASCORBYL PHOSPHATE SALTS.

    Science.gov (United States)

    Khan, Hira; Akhtar, Naveed; Ali, Atif; Khan, Haji M Shoaib; Sohail, Muhammad; Naeem, Muhammad; Nawaz, Zarqa

    2016-09-01

    Stability of hydrophilic and lipophilic vitamin C derivatives for quenching synergistic antioxidant activities and to treat oxidative related diseases is a major issue. This study was aimed to encapsulate hydrophilic and lipophilic vitamin C derivatives (ascorbyl palmitate and sodium ascorbyl phosphate) as functional ingredients in a newly formulated multiple emulsion of the W//W type to attain the synergistic antioxidant effects and the resultant system's long term physical and chemical stability. Several multiple emulsions using the same concentration of emulsifiers but different concentrations of ascorbyl palmitate and sodium ascorbyl phosphate were developed. Three finally selected multiple emulsions (ME₁, ME₂ and ME₃) were evaluated for physical stability in terms of rheology, microscopy, conductivity, pH, and organoleptic characteristics under different storage conditions for 3 months. Chemical stability was determined by HPLC on Sykam GmbH HPLC system (Germany), equipped with a variable UV detector. Results showed that at accelerated storage conditions all the three multiple emulsions had shear thinning behavior of varying shear stress with no influence of location of functional ingredients in a carrier system. Conductivity values increased and pH values remained within the skin pH range for 3 months. Microscopic analysis showed an increase in globule size with the passage of time, especially at higher temperatures while decreased at low temperatures. Centrifugation test did not cause phase separation till the 45th day, but little effects after 2 months. Chemical stability analysis by HPLC at the end of 3 months showed that ascorbyl palmitate and sodium ascorbyl phosphate were almost stable in all multiple emulsions with no influence of their location in a carrier system. Multiple emulsions were found a stable carrier for hydrophilic and lipophilic vitamin C derivatives to enhance their desired effects. Considering that many topical formulations

  7. Chemical stability of astaxanthin integrated into a food matrix: Effects of food processing and methods for preservation.

    Science.gov (United States)

    Martínez-Delgado, Alejandra Anahí; Khandual, Sanghamitra; Villanueva-Rodríguez, Socorro Josefina

    2017-06-15

    Astaxanthin is a carotenoid pigment found in numerous organisms ranging from bacteria to algae, yeasts, plants, crustaceans and fish such as salmon. Technological importance of this pigment emerged from various studies demonstrating that it is a powerful antioxidant, even with higher activity than alpha-tocopherol and other carotenoids. It has been included in various pharmaceutical products because of several beneficial properties. By its nature, astaxanthin is susceptible to degradation and can undergo chemical changes during food processing. Therefore, different studies have focused on improving the stability of the carotenoid under conditions such as high temperatures, pressures and mechanical force, among others. In this review, common processes involved in food processing and their effect on the stability of astaxanthin, integrated into a food matrix are discussed. Moreover, preservation techniques such as microencapsulation, inclusion in emulsions, suspensions, liposomes, etc., that are being employed to maintain stability of the product are also reviewed. Copyright © 2016 Elsevier Ltd. All rights reserved.

  8. Chemical Stability of Cd(II and Cu(II Ionic Imprinted Amino-Silica Hybrid Material in Solution Media

    Directory of Open Access Journals (Sweden)

    Buhani, Narsito, Nuryono, Eko Sri Kunarti

    2015-12-01

    Full Text Available Chemical stability of Cd(II and Cu(II ionic imprinted hybrid material of (i-Cd-HAS and i-Cu-HAS derived from silica modification with active compound (3-aminopropyl-trimethoxysilane (3-APTMS has been studied in solution media. Stability test was performed with HNO3 0.1 M (pH 1.35 to investigate material stability at low pH condition, CH3COONa 0.1 M (pH 5.22 for adsorption process optimum pH condition, and in the water (pH 9.34 for base condition. Material characteristics were carried out with infrared spectrophotometer (IR and atomic absorption spectrophotometer (AAS. At interaction time of 4 days in acid and neutral condition, i-Cd-HAS is more stable than i-Cu-HAS with % Si left in material 95.89 % (acid media, 43.82 % (close to neutral, and 9.39 % (base media.Keywords: chemical stability, amino-silica hybrid, ionic imprinting technique

  9. Chemical Stability of Cd(II and Cu(II Ionic Imprinted Amino-Silica Hybrid Material in Solution Media

    Directory of Open Access Journals (Sweden)

    Buhani Buhani

    2012-02-01

    Full Text Available Chemical stability of Cd(II and Cu(II ionic imprinted amino-silica (HAS material of (i-Cd-HAS and i-Cu-HAS derived from silica modification with active compound (3-aminopropyl-trimethoxysilane (3-APTMS has been studied in solution media.  Stability test was performed with HNO3 0.1 M (pH 1.35 to investigate material stability at low pH condition, acetat buffer at pH 5.22 for adsorption process optimum pH condition, and in the water (pH 9.34 for base condition.  Material characteristics were carried out with infrared spectrophotometer (IR and atomic absorption spectrophotometer (AAS.  At interaction time of 4 days in acid and neutral condition, i-Cd-HAS is more stable than i-Cu-HAS with % Si left in material 95.89 % (acid media, 43.82 % (close to neutral, and 9.39 % (base media.Keywords: chemical stability, amino-silica hybrid, ionic imprinting technique.

  10. Effect of stabilizers on the physico-chemical and sensory attributes ...

    African Journals Online (AJOL)

    Stabilized thermized yoghurt was produced by the addition of gelatin, carboxyl methyl cellulose (CMC) and corn starch, into yoghurt mix as stabilizers, each at 0, 0.5, 0.75 and 1.0% concentrations. The yoghurt samples produced after pasteurization of the mix, cooling, inoculation of starter culture and incubation for about 16 ...

  11. Stability issues of conjugated polymer / fullerene solar cells from a chemical viewpoint

    NARCIS (Netherlands)

    Hummelen, J.C.; Knol, J.; Sánchez, L.

    2001-01-01

    The efficiency of energy conversion and the stability or lifetime of ‘plastic’ photovoltaic cells, based on conjugated polymer/ fullerene blends, are the two main issues to be improved for this type of devices. The stability of these PV cells depends potentially on a large number of factors. A brief

  12. Storage stability of margarines produced from enzymatically interesterified fats compared to those prepared by conventional methods - Chemical properties

    DEFF Research Database (Denmark)

    Zhang, Hong; Jacobsen, Charlotte; Pedersen, Lars Saaby

    2006-01-01

    margarines in a pilot plant. Storage stability studies were carried out at storage temperatures of 5 and 25øC for 12wk. Margarines from the enzymatically interesterified fats were compared to the margarines produced by the conventional methods (chemical interesterification and physical blending......In this study, four margarine hardstocks were produced, two from enzymatically interesterified fats at 80 and 100% conversion, one from chemically randomized fat and one from physically mixed fat. These four hardstocks, blended with 50% sunflower oil, were mainly used for the production of table...... interesterified fat had higher PV in weeks4, 8 and10 than the margarines produced from the enzymatically interesterified fats and the physically blended fat. These differences were not caused by different contents of tocopherols in the hardstocks. The differences between the processes for chemical and enzymatic...

  13. Influence of particle size and preparation methods on the physical and chemical stability of amorphous simvastatin

    DEFF Research Database (Denmark)

    Zhang, Fang; Aaltonen, Jaakko; Tian, Fang

    2009-01-01

    This study investigated the factors influencing the stability of amorphous simvastatin. Quench-cooled amorphous simvastatin in two particle size ranges, 150-180 microm (QC-big) and ... compared to the crystalline form. The rank of solubility was found to be QC-big=QC-small>CM>crystalline. For the physical stability, the highest crystallization rate was observed for CM, and the slowest rate was detected for QC-big, with an intermediate rate occurring for QC-small. QC exhibited lower...

  14. Chemical and physical aspects of the stability of mica on heating

    International Nuclear Information System (INIS)

    Muromtsev, V.A.; Arkhangel'skii, S.V.; Egorov, S.V.

    1989-01-01

    An attempt was made in this study to comparatively determine the degree of hydration and thermal stability of micas and to analyze the possible causes of differences in interpreting the results on establishment of the degree of hydration on the example of phlogopites from the Kovdor and Aldan deposits by methods of flame photometry, γ-radiometric determination of K 2 O, thermal stability, and gravimetric methods of analysis of the moisture content and weight loss in calcination

  15. A study on the chemical stability and electrode performance of modified NiO cathodes for molten carbonate fuel cells

    International Nuclear Information System (INIS)

    Kim, Seung-Goo; Yoon, Sung Pil; Han, Jonghee; Nam, Suk Woo; Lim, Tae Hoon; Oh, In-Hwan; Hong, Seong-Ahn

    2004-01-01

    The chemical stabilities of modified NiO cathodes doped with 1.5 mol% CoO and 1.5 mol% LiCoO 2 fabricated by a conventional tape casting method were evaluated through the real MCFC single cell operation. The heat-treated samples before oxidation had proper porosities and microstructures for a MCFC cathode. At 150 mA cm -2 in current density, the MCFC single cell using a CoO-doped NiO cathode showed stable cell voltages in the range of 0.833-0.843 V for 1000 h. In contrast, the cell using a LiCoO 2 -doped NiO cathode with a maximum of 0.836 V at 500 h degraded to 0.826 V at 1000 h due to a wet seal breakdown at the cathode side. The amounts of nickel precipitated in the electrolytes of the cells using modified NiO cathodes doped with CoO and LiCoO 2 after the operation for 1000 h were 1.2 and 1.4 wt.%, respectively, which were about 60% lower than that of the standard cells using pure NiO cathodes. The enhanced chemical stability of modified NiO cathodes seems to be attributed to the fact that the presence of cobalt increases the lithium content in the cathodes by converting Ni 2+ to Ni 3+ , resulting in stabilizing the layered crystal structure

  16. EFFECT OF STABILIZERS ON THE CHEMICAL AND PHOTODEGRADATION OF ASCORBIC ACID IN AQUEOUS SOLUTION

    Directory of Open Access Journals (Sweden)

    Iqbal Ahmad

    2016-06-01

    Full Text Available Ascorbic acid (vitamin C is susceptible to light and air and forms various degradation products. A number of stabilizers have been used to study their effect on the degradation of ascorbic acid (AH2 in dark and light at pH 4.0 and 6.0 alone and in combination with citric and tartaric acids. The assay of AH2 in degraded solutions was performed by a specific UV spectrometric method. The degradation product of AH2 at pH 4.0 and 6.0 was identified as dehydroascorbic acid. The degradation of AH2 has been found to follow first-order kinetics. The apparent first-order rate constants, t90 and percent inhibition in rate in the presence of stabilizers and the second-order rate constants for the interaction of stabilizers with AH2 have been determined. The highest stabilizing effect on AH2 was found by sodium metabisulfite, followed by sodium sulfite, sodium bisulfate, sodium thiosulfate and thiourea. The pH of the solutions has also been found to influence the degradation of AH2 as the rates are higher at pH 6.0 compared to those of pH 4.0, probably due to the ionization of AH2. A synergistic effect has been observed when citric or tartaric acid was added to the solutions containing stabilizers where citric acid showed comparatively better effect.

  17. Chemical stabilization of metals and arsenic in contaminated soils using oxides – A review

    International Nuclear Information System (INIS)

    Komárek, Michael; Vaněk, Aleš; Ettler, Vojtěch

    2013-01-01

    Oxides and their precursors have been extensively studied, either singly or in combination with other amendments promoting sorption, for in situ stabilization of metals and As in contaminated soils. This remediation option aims at reducing the available fraction of metal(loid)s, notably in the root zone, and thus lowering the risks associated with their leaching, ecotoxicity, plant uptake and human exposure. This review summarizes literature data on mechanisms involved in the immobilization process and presents results from laboratory and field experiments, including the subsequent influence on higher plants and aided phytostabilization. Despite the partial successes in the field, recent knowledge highlights the importance of long-term and large-scale field studies evaluating the stability of the oxide-based amendments in the treated soils and their efficiency in the long-term. - In situ stabilization of metals and As in contaminated soils using oxides combined with phytostabilization is a potential alternative to conventional remediation techniques.

  18. There Is Still Room for Improvement: Presentation of a Neutral Borosilicate Glass with Improved Chemical Stability for Parenteral Packaging.

    Science.gov (United States)

    Boltres, Bettine; Tratzky, Stephan; Kass, Christof; Eichholz, Rainer; Naß, Peter

    2016-01-01

    For pharmaceutical parenteral packaging the glass compositions have always been either Type I borosilicate or Type III soda-lime glass. As both the compositions and certain chemical and physical properties are mandated by international standards, there has not been room for any changes. However, by applying only minor adjustments, a borosilicate glass was developed that showed improved chemical stability. The chemical composition is still in the range of currently used borosilicate glasses, which makes it a Type I glass according to all current pharmacopeia. A study was performed on glass vials comparing the new glass with the standard FIOLAX(®) and two other publicly available glasses. In an extraction study with water at 121 °C the new glass showed the highest chemical stability with the lowest amount of extractables. In an accelerated ageing study, which was done with water, phosphate, and carbonate buffer at 40 °C for 12 months, the new glass also proved to have the lowest amount of leachables. In this article the new glass and the results from the studies are presented, showing the reader how much of an effect can be attained with only minor adjustments if the scientific fundamentals are clear. The pharmaceutical market has been quite constant and risk-oriented due to the high impact on the safety of the patient. As any change necessitates a complicated change process, this has, in consequence, lead the industry to resist changing the parenteral primary packaging material for decades. The main glasses have either been Type I borosilicate or Type III soda-lime glass. On the other hand, a combination of improved inspection systems and the development of more sensitive biologically based drugs has elevated the standards for parental packaging materials. For example, the measurement of extractables and leachables from the packaging material steadily came into focus. In this article, a new glass is presented that still belongs to the group of Type I borosilicate

  19. Performance of a novel microwave-based treatment technology for atrazine removal and destruction: Sorbent reusability and chemical stability, and effect of water matrices

    Energy Technology Data Exchange (ETDEWEB)

    Hu, Erdan; Hu, Yuanan [State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640 (China); Cheng, Hefa, E-mail: hefac@umich.edu [State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640 (China); MOE Laboratory for Earth Surface Processes, College of Urban and Environmental Sciences, Peking University, Beijing 100871 (China)

    2015-12-15

    Highlights: • Cu{sup 2+} and Fe{sup 3+} in zeolite pores enhance atrazine sorption and MW-induced degradation. • Exchanged zeolites perform well over multiple sorption–regeneration cycles. • Fe{sup 3+} species in the zeolite micropores have much greater stability than those of Cu{sup 2+}. • DOC in natural waters can compromise the sorption capacity of exchanged zeolites. • Iron-exchanged dealuminated Y zeolites hold great promise for practical applications. - Abstract: Transition metal-exchanged dealuminated Y zeolites were used to adsorb atrazine from aqueous solutions, followed by regeneration of the sorbents and destruction of the sorbed atrazine with microwave irradiation. Exchange of copper and iron into the zeolite's micropores significantly enhanced its sorption capacity and selectivity toward atrazine, and increased the microwave-induced degradation rate of the sorbed atrazine by 3–4-folds. Both the copper- and iron-exchanged zeolites could be regenerated and reused multiple times, while the catalytic activity of the latter was more robust due to the much greater chemical stability of Fe{sup 3+} species in the micropores. The presence of humic acid, and common cations and anions had little impact on the sorption of atrazine on the transition metal-exchanged zeolites. In the treatment of atrazine spiked in natural surface water and groundwater samples, sorptive removal of atrazine was found to be impacted by the level of dissolved organic carbon, probably through competition for the micropore spaces and pore blocking, while the water matrices exhibited no strong effect on the microwave-induced degradation of sorbed atrazine. Overall, iron-exchanged dealuminated Y zeolites show great potential for removal and destruction of atrazine from contaminated surface water and groundwater in practical implementation of the novel treatment technology.

  20. Performance of a novel microwave-based treatment technology for atrazine removal and destruction: Sorbent reusability and chemical stability, and effect of water matrices

    International Nuclear Information System (INIS)

    Hu, Erdan; Hu, Yuanan; Cheng, Hefa

    2015-01-01

    Highlights: • Cu"2"+ and Fe"3"+ in zeolite pores enhance atrazine sorption and MW-induced degradation. • Exchanged zeolites perform well over multiple sorption–regeneration cycles. • Fe"3"+ species in the zeolite micropores have much greater stability than those of Cu"2"+. • DOC in natural waters can compromise the sorption capacity of exchanged zeolites. • Iron-exchanged dealuminated Y zeolites hold great promise for practical applications. - Abstract: Transition metal-exchanged dealuminated Y zeolites were used to adsorb atrazine from aqueous solutions, followed by regeneration of the sorbents and destruction of the sorbed atrazine with microwave irradiation. Exchange of copper and iron into the zeolite's micropores significantly enhanced its sorption capacity and selectivity toward atrazine, and increased the microwave-induced degradation rate of the sorbed atrazine by 3–4-folds. Both the copper- and iron-exchanged zeolites could be regenerated and reused multiple times, while the catalytic activity of the latter was more robust due to the much greater chemical stability of Fe"3"+ species in the micropores. The presence of humic acid, and common cations and anions had little impact on the sorption of atrazine on the transition metal-exchanged zeolites. In the treatment of atrazine spiked in natural surface water and groundwater samples, sorptive removal of atrazine was found to be impacted by the level of dissolved organic carbon, probably through competition for the micropore spaces and pore blocking, while the water matrices exhibited no strong effect on the microwave-induced degradation of sorbed atrazine. Overall, iron-exchanged dealuminated Y zeolites show great potential for removal and destruction of atrazine from contaminated surface water and groundwater in practical implementation of the novel treatment technology.

  1. SS-mPEG chemical modification of recombinant phospholipase C for enhanced thermal stability and catalytic efficiency.

    Science.gov (United States)

    Fang, Xian; Wang, Xueting; Li, Guiling; Zeng, Jun; Li, Jian; Liu, Jingwen

    2018-05-01

    PEGylation is one of the most promising and extensively studied strategies for improving the properties of proteins as well as enzymic physical and thermal stability. Phospholipase C, hydrolyzing the phospholipids offers tremendous applications in diverse fields. However, the poor thermal stability and higher cost of production have restricted its industrial application. This study focused on improving the stabilization of recombinant PLC by chemical modification with methoxypolyethylene glycol-Succinimidyl Succinate (SS-mPEG, MW 5000). PLC gene from isolate Bacillus cereus HSL3 was fused with SUMO, a novel small ubiquitin-related modifier expression vector and over expressed in Escherichia coli. The soluble fraction of SUMO-PLC reached 80% of the total recombinant protein. The enzyme exhibited maximum catalytic activity at 80 °C and was relatively thermostable at 40-70 °C. It showed extensive substrate specificity pattern and marked activity toward phosphatidylcholine, which made it a typical non-specific PLC for industrial purpose. SS-mPEG-PLC complex exhibited an enhanced thermal stability at 70-80 °C and the catalytic efficiency (K cat /K m ) had increased by 3.03 folds compared with free PLC. CD spectrum of SS-mPEG-PLC indicated a possible enzyme aggregation after chemical modification, which contributed to the higher thermostability of SS-mPEG-PLC. The increase of antiparallel β sheets in secondary structure also made it more stable than parallel β sheets. The presence of SS-mPEG chains on the enzyme molecule surface somewhat changed the binding rate of the substrates, leading to a significant improvement in catalytic efficiency. This study provided an insight into the addition of SS-mPEG for enhancing the industrial applications of phospholipase C at higher temperature. Copyright © 2018 Elsevier B.V. All rights reserved.

  2. High pressure stability analysis and chemical bonding of Ti1-xZrxN alloy: A first principle study

    International Nuclear Information System (INIS)

    Chauhan, Mamta; Gupta, Dinesh C.

    2016-01-01

    First-principles pseudo-potential calculations have been performed to analyze the stability of Ti 1-x Zr x N alloy under high pressures. The first order phase transition from B1 to B2 phase has been observed in this alloy at high pressure. The variation of lattice parameter with the change in concentration of Zr atom in Ti 1-x Zr x N is also reported in both the phases. The calculations for density of states have been performed to understand the alloying effects on chemical bonding of Ti-Zr-N alloy.

  3. The effect of lunar soil, metal oxides on thermal and radio-chemical stability of amino acids

    International Nuclear Information System (INIS)

    Khenokh, M.A.; Lapinskaya, E.M.

    1983-01-01

    Data on study of the effect of lunar soil and some metal oxides characteristic both for land and sea basaltS of lunar sojls on thermal and radio-chemical stability of amino acids are presented. The data obtained permit to suppose that extremely small quantity of amino acids discovered in lunar soil is conditioned by their decomposition under combined effect of different types of radiation, solar wind and sharp change of temperature. Probably, the effect of soil on photochemical activity of UV-radiation of the Sun and solid-phase radiolysis is not practically observed

  4. Anatase thin film with diverse epitaxial relationship grown on yttrium stabilized zirconia substrate by chemical vapor deposition

    International Nuclear Information System (INIS)

    Miyagi, Takahira; Ogawa, Tomoyuki; Kamei, Masayuki; Wada, Yoshiki; Mitsuhashi, Takefumi; Yamazaki, Atsushi

    2003-01-01

    An anatase epitaxial thin film with diverse epitaxial relationship, YSZ (001) // anatase (001), YSZ (010) // anatase (110), was grown on a single crystalline yttrium stabilized zirconia (YSZ) (001) substrate by metal organic chemical vapor deposition (MOCVD). The full width at half maximum (FWHM) of the (004) reflection of this anatase epitaxial film was 0.4deg, and the photoluminescence of this anatase epitaxial film showed visible emission with broad spectral width and large Stokes shift at room temperature. These results indicate that this anatase epitaxial film possessed almost equal crystalline quality compared with that grown under identical growth conditions on single crystalline SrTiO 3 substrate. (author)

  5. Co-milled API-lactose systems for inhalation therapy: impact of magnesium stearate on physico-chemical stability and aerosolization performance.

    Science.gov (United States)

    Lau, Michael; Young, Paul M; Traini, Daniela

    2017-06-01

    Particle micronization for inhalation can impart surface disorder (amorphism) of crystalline structures. This can lead to stability issues upon storage at elevated humidity from recrystallization of the amorphous state, which can subsequently affect the aerosol performance of the dry powder formulation. The aim of this study was to investigate the impact of an additive, magnesium stearate (MGST), on the stability and aerosol performance of co-milled active pharmaceutical ingredient (API) with lactose. Blends of API-lactose with/without MGST were prepared and co-milled by the jet-mill apparatus. Samples were stored at 50% relative humidity (RH) and 75% RH for 1, 5, and 15 d. Analysis of changes in particle size, agglomerate structure/strength, moisture sorption, and aerosol performance were analyzed by laser diffraction, scanning electron microscopy (SEM), dynamic vapor sorption (DVS), and in-vitro aerodynamic size assessment by impaction. Co-milled formulation with MGST (5% w/w) led to a reduction in agglomerate size and strength after storage at elevated humidity compared with co-milled formulation without MGST, as observed from SEM and laser diffraction. Hysteresis in the sorption/desorption isotherm was observed in the co-milled sample without MGST, which was likely due to the recrystallization of the amorphous regions of micronized lactose. Deterioration in aerosol performance after storage at elevated humidity was greater for the co-milled samples without MGST, compared with co-milled with MGST. MGST has been shown to have a significant impact on co-milled dry powder stability after storage at elevated humidity in terms of physico-chemical properties and aerosol performance.

  6. Quantum chemical evaluation for the stability of liquid sodium containing titanium nanoparticles

    International Nuclear Information System (INIS)

    Suzuki, Ai; Inaba, Kenji; Ishizawa, Yukie; Miura, Ryuji; Hatakeyama, Nozomu; Miyamoto, Akira; Saito, Jun-ichi; Ara, Kuniaki

    2015-01-01

    Recently, liquid sodium containing titanium nanoparticles (LSnanop) have attracted considerable attention. In this study, suspension state of Ti nanoparticle in liquid sodium was quantum chemically evaluated. The atomic interaction between Ti nanoparticles and sodium atoms in the liquid sodium medium was investigated. There were some literatures which gained quantum chemical insight into a nanoparticle with the surrounding sodium atom. However, liquid sodium medium itself together with a Ti nanoparticle under the realistic temperature has not yet been investigated theoretically. To overcome the problem of conventional theoretical method, we applied computationally low-load Tight Binding Quantum Chemical Molecular Dynamics (TB-QCMD) calculation method to investigate the suspension state of the Ti nanoparticle in liquid sodium metal. (author)

  7. Invariant boxes and stability of some systems from biomathematics and chemical reactions

    International Nuclear Information System (INIS)

    Pavel, N.H.

    1984-08-01

    A general theorem on the flow-invariance of a time-dependent rectangular box with respect to a differential system is first recalled [''Analysis of some non-linear problems'' in Banach Spaces and Applications, Univ. of Iasi (Romania) (1982)]. Then a theorem applicable to the study of some differential systems from biomathematics and chemical reactions is given and proved. The theorem can be applied to enzymatic reactions, the chemical mechanism in the Belousov reaction, and the kinetic system for the chemical scheme of Hanusse of two processes with three intermediate species [in Pavel, N.H., Differential Equations, Flow-invariance and Applications, Pitman Publishing, Ltd., London (to appear)]. Next, the matrices A for which the corresponding linear system x'=Ax is component-wise positive asymptotically stable are characterized. In the Appendix a partial answer to an open problem regarding the preservation of both continuity and dissipativity in the extension of functions to a Banach space is given

  8. Stabilization of enzymatically polymerized phenolic chemicals in a model soil organic matter-free geomaterial.

    Science.gov (United States)

    Palomo, Mónica; Bhandari, Alok

    2012-01-01

    A variety of remediation methods, including contaminant transformation by peroxidase-mediated oxidative polymerization, have been proposed to manage soils and groundwater contaminated with chlorinated phenols. Phenol stabilization has been successfully observed during cross polymerization between phenolic polymers and soil organic matter (SOM) for soils with SOM >3%. This study evaluates peroxidase-mediated transformation and removal of 2,4-dichlorophenol (DCP) from an aqueous phase in contact with a natural geomaterial modified to contain negligible (soils with higher SOM. The SOM-free sorbent was generated by removing SOM using a NaOCl oxidation. When horseradish peroxidase (HRP) was used to induce polymerization of DCP, the soil-water phase distribution relationship (PDR) of DCP polymerization products (DPP) was complete within 1 d and PDRs did not significantly change over the 28 d of study. The conversion of DCP to DPP was close to 95% efficient. Extractable solute consisted entirely of DPP with 5% or less of unreacted DCP. The aqueous extractability of DPP from SOM-free geomaterial decreased at longer contact times and at smaller residual aqueous concentrations of DPP. DCP stabilization appeared to have resulted from a combination of sorption, precipitation, and ligand exchange between oligomeric products and the exposed mineral surfaces. Modification of the mineral surface through coverage with DPP enhanced the time-dependent retention of the oligomers. DPP stabilization in SOM-free geomaterial was comparable with that reported in the literature with soil containing SOM contents >1%. Results from this study suggest that the effectiveness of HRP-mediated stabilization of phenolic compounds not only depends on the cross-coupling with SOM, but also on the modification of the surface of the sorbent that can augment affinity with oligomers and enhance stabilization. Coverage of the mineral surface by phenolic oligomers may be analogous to SOM that can potentially

  9. Evaluation of quantum-chemical methods of radiolysis stability for macromolecular structures

    International Nuclear Information System (INIS)

    Postolache, Cristian; Matei, Lidia

    2005-01-01

    The behavior of macromolecular structures in ionising fields was analyzed by quantum-chemical methods. In this study the primary radiolytic effect was analyzed using a two-step radiolytic mechanism: a) ionisation of molecule and spatial redistribution of atoms in order to reach a minimum value of energy, characteristic to the quantum state; b) neutralisation of the molecule by electron capture and its rapid dissociation into free radicals. Chemical bonds suspected to break are located in the distribution region of LUMO orbital and have minimal homolytic dissociation energies. Representative polymer structures (polyethylene, polypropylene, polystyrene, poly α and β polystyrene, polyisobutylene, polytetrafluoroethylene, poly methylsiloxanes) were analyzed. (authors)

  10. Chemical functionalization and stabilization of type I collagen with organic tanning agents

    International Nuclear Information System (INIS)

    Albu, Madalina Georgiana; Deselnicu, Viorica; Ioannidis, Ioannis; Deselnicu, Dana; Chelaru, Ciprian

    2015-01-01

    We investigated the interactions between selected organic tanning agents and type I fibrillar collagen as a model fibrillar substrate to enable the fast direct evaluation and validation of interpretations of tanning activity. Type I fibrillar collagen (1%) as gel was used as substrate of tanning and tannic acid, resorcinol- and melamine-formaldehyde and their combination at three concentrations as crosslinking agents (tannins). To evaluate the stability of collagen during tanning, the crosslinked gels at 2.8, 4.5 and 9.0 pHs were freeze-dried as discs which were characterized by FTIR, shrinkage temperature, enzymatic degradation and optical microscopy, and the results were validated by statistical analyses. The best stability was given by combinations between resorcinol- and melamine-formaldehyde at isoelectric pH

  11. Chemical functionalization and stabilization of type I collagen with organic tanning agents

    Energy Technology Data Exchange (ETDEWEB)

    Albu, Madalina Georgiana; Deselnicu, Viorica; Ioannidis, Ioannis; Deselnicu, Dana; Chelaru, Ciprian [Leather and Footwear Research Institute, Bucharest (Romania)

    2015-02-15

    We investigated the interactions between selected organic tanning agents and type I fibrillar collagen as a model fibrillar substrate to enable the fast direct evaluation and validation of interpretations of tanning activity. Type I fibrillar collagen (1%) as gel was used as substrate of tanning and tannic acid, resorcinol- and melamine-formaldehyde and their combination at three concentrations as crosslinking agents (tannins). To evaluate the stability of collagen during tanning, the crosslinked gels at 2.8, 4.5 and 9.0 pHs were freeze-dried as discs which were characterized by FTIR, shrinkage temperature, enzymatic degradation and optical microscopy, and the results were validated by statistical analyses. The best stability was given by combinations between resorcinol- and melamine-formaldehyde at isoelectric pH.

  12. Chemical stabilization of metals and arsenic in contaminated soils using oxides--a review.

    Science.gov (United States)

    Komárek, Michael; Vaněk, Aleš; Ettler, Vojtěch

    2013-01-01

    Oxides and their precursors have been extensively studied, either singly or in combination with other amendments promoting sorption, for in situ stabilization of metals and As in contaminated soils. This remediation option aims at reducing the available fraction of metal(loid)s, notably in the root zone, and thus lowering the risks associated with their leaching, ecotoxicity, plant uptake and human exposure. This review summarizes literature data on mechanisms involved in the immobilization process and presents results from laboratory and field experiments, including the subsequent influence on higher plants and aided phytostabilization. Despite the partial successes in the field, recent knowledge highlights the importance of long-term and large-scale field studies evaluating the stability of the oxide-based amendments in the treated soils and their efficiency in the long-term. Copyright © 2012 Elsevier Ltd. All rights reserved.

  13. Organic Redox Species in Aqueous Flow Batteries: Redox Potentials, Chemical Stability and Solubility

    OpenAIRE

    Kristina Wedege; Emil Dražević; Denes Konya; Anders Bentien

    2016-01-01

    Organic molecules are currently investigated as redox species for aqueous low-cost redox flow batteries (RFBs). The envisioned features of using organic redox species are low cost and increased flexibility with respect to tailoring redox potential and solubility from molecular engineering of side groups on the organic redox-active species. In this paper 33, mainly quinone-based, compounds are studied experimentially in terms of pH dependent redox potential, solubility and stability, combined ...

  14. Physical and Chemical Stability of Urapidil in 0.9% Sodium Chloride in Elastomeric Infusion Pump.

    Science.gov (United States)

    Tomasello, Cristina; Leggieri, Anna; Rabbia, Franco; Veglio, Franco; Baietto, Lorena; Fulcheri, Chiara; De Nicolò, Amedeo; De Perri, Giovanni; D'Avolio, Antonio

    2016-01-01

    Urapidil is an antihypertensive agent, usually administered through intravenous bolus injection, slow-intravenous infusion, or continuous-drug infusion by perfusor. Since to date no evidences are available on drug stability in elastomeric pumps, patients have to be hospitalized. The purpose of this study was to validate an ultra-performance liquid chromatographic method to evaluate urapidil stability in an elastomeric infusion pump, in order to allow continuous infusion as home-care treatment. Analyses were conducted by diluting urapidil in an elastomeric pump. Two concentrations were evaluated: 1.6 mg/mL and 3.3 mg/mL. For the analyses, a reverse-phase ultra-performance liquid chromatographic- photodiode array detection instrument was used. Stressed degradation, pH changes, and visual clarity were used as stability indicators up to 10 days after urapidil solution preparation. The drug showed no more than 5% degradation during the test period at room temperature. No pH changes and no evidences of incompatibility were observed. Stress tests resulted in appreciable observation of degradation products. Considering the observed mean values, urapidil hydrochloride in sodium chloride 0.9% in elastomeric infusion pumps is stable for at least 10 days. These results indicate that this treatment could be administered at home for a prolonged duration (at least 7 days) with a satisfactory response. Copyright© by International Journal of Pharmaceutical Compounding, Inc.

  15. Influence of chemical treatment on dimensional stability of narrow-leaved ash - part one: Tangential swelling

    Directory of Open Access Journals (Sweden)

    Popović Jasmina

    2012-01-01

    Full Text Available Dimensional change in wood occurs with the change in hygroscopic moisture content, as a consequence of available hydroxyl groups in wood constituents, allowing for the hydrogen bonding with water molecules. Various pretreatments of wood material are being frequently applied in the wood processing industry. One of the main effects of such processes is the hydrolysis of hemicelluloses, which is the main carrier of the free hydroxyl groups in wood material. Hence, the influence of water treatment and the acetic acid treatment on dimensional stability of narrow-leaved ash (Fraxinus angustifolia Vahl. ssp. Pannonica Soó & Simon were examined in this paper. Duration of treatments was 1h, 2h, 3h and 4h for both solvents. In addition the acetic acid was separately used in concentrations of 3% and 6%. Dimensional stability of the control (referent and treated sample groups were tested on oven dried samples which were consequently submerged in the distilled water during 32 days. The increase of dimensional stability of narrow-leaved ash was achieved with all of the three treatments (one treatment with water and the two with acetic acid solutions. Simultaneously, it was noticed that the results of water uptake and tangential swelling were not significantly affected by the duration (length of the treatments. [Projekat Ministarstva nauke Republike Srbije, br. TP-031041

  16. Mechanical properties and chemical stability of pivalolactone-based poly(ether ester)s

    NARCIS (Netherlands)

    Tijsma, E.J.; Tijsma, E.J.; van der Does, L.; Bantjes, A.; Bantjes, A.; Vulic, I.

    1994-01-01

    The processing, mechanical and chemical properties of poly(ether ester)s, prepared from pivalolactone (PVL), 1,4-butanediol (4G) and dimethyl terephthalate (DMT), were studied. The poly(ether ester)s could easily be processed by injection moulding, owing to their favourable rheological and thermal

  17. Validation and refinement of chemical stabilization procedures for pavement subgrade soils in Oklahoma : volume I.

    Science.gov (United States)

    2011-07-01

    Additions of byproduct chemicals, such as fly ash or cement kiln dust, have been shown to increase the unconfined compression strength (UCS) of soils. To be considered effective, the soil must exhibit a strength increase of at least 50 psi. Many curr...

  18. Stability fields of smectites and illites as a function of temperature and chemical composition

    International Nuclear Information System (INIS)

    Tardy, Y.; Duplay, J.; Fritz, B.; Strasbourg-1 Univ., 67

    1987-04-01

    A thermodynamic ideal solid solution analogue is proposed which accounts the correlations which clearly reflect the temperatures at which the nonmineralic population are supposed to have been formed. The solid solution is considered, at a particle scale, as an ideal mixture of individual layers, weakly bent each to the next. Each layer presents the chemical composition of a given end member, so that the proportions of the different end members change from one particle to another. Considering one particle of a given chemical composition, the multipole solid solution theory allows to calculate the wheighted contributions of each end member into the ideal clay solid solution along with the chemical composition of the aqueous solutions in equilibrium with the considered particle in its independent microenvironment. This model is able to predict the nature of the chemical correlations which are expected, at a given temperature, within a given population. This model is also applied to the prediction of the temperature required for the conversion of smectite into illite during the burial diagenesis. (orig./HP)

  19. Isoparaffin diluents for tri-n-butyl phosphate. Chemical, radiation-chemical stability, effect on solvent extraction of tetravalet plutonium and thorium

    International Nuclear Information System (INIS)

    Renard, Eh.V.; Pyatibratov, Yu.P.; Neumoev, N.V.

    1988-01-01

    45-90% conversion degree of n-paraffin into branched isoparaffin with mono- and dimethyl structure is achieved by means of catalytic hydroisomerization of n-paraffin raw material in reactor with alumoplatinum catalyser. Isoparaffin (99%) concentrates with constant molecular mass from iso-C 10 to iso-C 15 are produced of a batch of deeply isomerized n-paraffins. Plutonium and thorum nitrate solubility in 30% TBP solutions in iso-paraffins (iso-paraffin mixtures with similar C atom number) increases with the reduction of iso-paraffin molecular mass; system with 30% TBP in isodecane mixture is practically not stratified (∼ 104 g Pu/l, 22-25 deg C). By the main requirements to diluents for radiochemical extraction operations, including density, viscosity, boiling point flashed and freezines, chemical and radiation stability, radioruthenium and radiozirconium confinement systems, synthetic isoparaffin-containing solvents are as good as n-paraffins

  20. College Students' Conceptions of Chemical Stability: The Widespread Adoption of a Heuristic Rule out of Context and beyond Its Range of Application

    Science.gov (United States)

    Taber, Keith S.

    2009-01-01

    This paper reports evidence that learners commonly develop a notion of chemical stability that, whilst drawing upon ideas taught in the curriculum, is nevertheless inconsistent with basic scientific principles. A series of related small-scale studies show that many college-level students consider a chemical species with an octet structure, or a…

  1. Guia para a determinação da estabilidade de produtos químicos Guide for determining the stability of chemical products

    Directory of Open Access Journals (Sweden)

    Luciana R. Oriqui

    2013-01-01

    Full Text Available Companies worldwide are reviewing their working process to avoid waste, become aligned with environmental management standards and to fulfill specifications defined for national and international regulations. In this context, it is important that Brazilian Chemical companies have a specific stability guide for their products. The main purpose of this work is to present a stability guide for chemical products based on the existing guides of the Pharmaceutical and Cosmetics segments. Furthermore, this work proposes to offer an additional period of shelf life for chemical products, provided they meet certain prerequisites.

  2. Single crystal growth and surface chemical stability of KPb2Br5

    Science.gov (United States)

    Atuchin, V. V.; Isaenko, L. I.; Kesler, V. G.; Tarasova, A. Yu.

    2011-03-01

    Single crystal of KPb2Br5 has been grown using the Bridgman technique. Initially the synthesis of stoichiometric KPb2Br5 compound was performed from high purity bromide salts. Electronic structure of KPb2Br5 has been determined with X-ray photoelectron spectroscopy for powdered sample fabricated by grinding in air. Drastic chemical interaction of KPb2Br5 with atmosphere has not been detected. Chemical bonding in potassium- and lead-containing bromides is considered using binding energy differences ΔK=(BE K 2p3/2-BE Br 3d) and ΔPb=(BE Pb 4f7/2-BE Br 3d), respectively, as representative parameters.

  3. Evaluation of chemical stability of vitrification media for radioactive waste products

    International Nuclear Information System (INIS)

    Barkatt, A.; Simmons, J.H.; Macedo, P.B.

    1981-01-01

    Test methods and test results concerning the measurement of chemical durability of glass media proposed for nuclear waste fixation are described. In order to develop predictive models and risk calculations, the release rates of individual components are measured. The results are used to determine matrix dissolution rates, possible transport of components through the matrix, and chemical and physical corrosion mechanisms. Measurements on model borosilicate and high silica glass fixation media are reported and discussed in terms of layer formation, approach to steady state, interaction of polyvalent ions with the dealkalised layer, structural disintegration of the layer, and the effects of glass composition and of environmental conditions (temperature, leachant composition and pH, γ dose). The extrapolation of short term laboratory tests to long time storage conditions and the use of such extrapolation in predicting safe upper limits for the release rates of components of the glass are described. (author)

  4. Film thickness and chemical processing effects on the stability of cadmium telluride solar cells

    International Nuclear Information System (INIS)

    Albin, D.S.; Demtsu, S.H.; McMahon, T.J.

    2006-01-01

    The performance and stability of CdS/CdTe solar cells as a function of layer thickness, back contact etch, and oxygen during the CdCl 2 anneal was determined. Multiple linear regression models were used to analyze the statistical significance of various first order effects and interactions. With stress, all devices showed a reduction in open-circuit voltage (V oc ) and fill factor (FF) characteristic of increased recombination. Devices using thinner CdS were vulnerable to shunt formation. Oxygen during the CdCl 2 anneal minimizes this effect. A thermodynamic model involving the formation of Cu-oxide is presented to explain the latter

  5. Study of stability of terrylitine chemically bound with polymer to γ-irradiation

    International Nuclear Information System (INIS)

    Yudanova, T.N.; Skokova, I.F.; Dovbij, E.V.; Kalashnik, A.T.

    1987-01-01

    Using ESR method the mechanism of the increase in stability to γ-irradiation of proteolytic enzyme terrylitine immobilized on cellulose derivatives, has been studied. It is shown that in the process of γ-sterilization by the doses of 25 kGy at the dose rate 1.1 Gy/s migration of terrylitine free valency to macromolecule of polymer-carrier takes place, and in certain cases recombination of enzyme and polymer macroradicals occurs. Due to the fact proteolytic activity of immobilized terrylitine during γ-sterilization does not decrease practically

  6. Calculation of the relative chemical stabilities of proteins as a function of temperature and redox chemistry in a hot spring.

    Directory of Open Access Journals (Sweden)

    Jeffrey M Dick

    Full Text Available Uncovering the chemical and physical links between natural environments and microbial communities is becoming increasingly amenable owing to geochemical observations and metagenomic sequencing. At the hot spring known as Bison Pool in Yellowstone National Park, the cooling of the water in the outflow channel is associated with an increase in oxidation potential estimated from multiple field-based measurements. Representative groups of proteins whose sequences were derived from metagenomic data also exhibit an increase in average oxidation state of carbon in the protein molecules with distance from the hot-spring source. The energetic requirements of reactions to form selected proteins used in the model were computed using amino-acid group additivity for the standard molal thermodynamic properties of the proteins, and the relative chemical stabilities of the proteins were investigated by varying temperature, pH and oxidation state, expressed as activity of dissolved hydrogen. The relative stabilities of the proteins were found to track the locations of the sampling sites when the calculations included a function for hydrogen activity that increases with temperature and is higher, or more reducing, than values consistent with measurements of dissolved oxygen, sulfide and oxidation-reduction potential in the field. These findings imply that spatial patterns in the amino acid compositions of proteins can be linked, through energetics of overall chemical reactions representing the formation of the proteins, to the environmental conditions at this hot spring, even if microbial cells maintain considerably different internal conditions. Further applications of the thermodynamic calculations are possible for other natural microbial ecosystems.

  7. Linking measurements of biodegradability, thermal stability and chemical composition to evaluate the effects of management on soil organic matter

    Science.gov (United States)

    Gregorich, Ed; Gillespie, Adam; Beare, Mike; Curtin, Denis; Sanei, Hamed; Yanni, Sandra

    2015-04-01

    The stability of soil organic matter (SOM) as it relates to resistance to microbial degradation has important implications for nutrient cycling, emission of greenhouse gases, and C sequestration. Hence, there is interest in developing new ways to accurately quantify and characterise the labile and stable forms of soil organic C. Our objectives in this study were to evaluate and describe relationships among the biodegradability, thermal stability and chemistry of SOM in soil under widely contrasting management regimes. Samples from the same soil under permanent pasture, an arable cropping rotation, and chemical fallow were fractionated (sand: 2000-50 μm; silt: 50-5 μm, and clay: managements and that sand-associated organic matter was significantly more susceptible than that in the silt or clay fractions. Analysis by XANES showed accumulation of carboxylates and strong depletion of amides (protein) and aromatics in the fallow whole soil. Moreover, protein depletion was most significant in the sand fraction of the fallow soil. Sand fractions in fallow and cropped soils were, however, enriched in plant-derived phenols, aromatics and carboxylates compared to the sand fraction of pasture soils. In contrast, ketones, which have been identified as products of microbially-processed organic matter, were slightly enriched in the silt fraction of the pasture soil. These data suggest reduced inputs and cropping restrict the decomposition of plant residues and, without supplemental N additions, protein-N in native SOM is significantly mineralized in fallow systems to meet microbial C mineralization demands. Analytical pyrolysis showed distinct differences in the thermal stability of SOM among the size fractions and management treatments; it also showed that the loss of SOM generally involved dehydrogenation. The temperature at which half of the C was pyrolyzed showed strong correlation with mineralizable C and thus provides solid evidence for a link between the biological and

  8. Starved air combustion-solidification/stabilization of primary chemical sludge from a tannery

    Energy Technology Data Exchange (ETDEWEB)

    Swarnalatha, S. [Department of Environmental Technology, Central Leather Research Institute, Adyar, Chennai-600 020, Tamil Nadu (India); Ramani, K. [Department of Environmental Technology, Central Leather Research Institute, Adyar, Chennai-600 020, Tamil Nadu (India); Karthi, A. Geetha [Department of Environmental Technology, Central Leather Research Institute, Adyar, Chennai-600 020, Tamil Nadu (India); Sekaran, G. [Department of Environmental Technology, Central Leather Research Institute, Adyar, Chennai-600 020, Tamil Nadu (India)]. E-mail: ganesansekaran@hotmail.com

    2006-09-01

    The high concentration of trivalent chromium along with organic/inorganic compounds in tannery sludge causes severe ground water contamination in the case of land disposal and chronic air pollution during incineration. In the present investigation, the sludge was subjected to flow-through column test to evaluate the concentration of leachable organics (tannin, COD and TOC) and heavy metal ions (Cr{sup 3+}, Fe{sup 2+}) present in it. The dried sludge was incinerated at 800 deg. C in an incinerator under starved oxygen supply (starved-air combustion) to prevent the conversion of Cr{sup 3+} to Cr{sup 6+}. The efficiency of starved air combustion was studied under different loading rates of sludge. The calcined sludge was solidified/stabilized using fly ash and Portland cement/gypsum. The solidified bricks were tested for unconfined compressive strength and heavy metal leaching. Unconfined compressive strength of the blocks was in the range of 83-156 kg/cm{sup 2}. The stabilization of chromium (III) in the cement gel matrix was confirmed with scanning electron microscopy (SEM) and X-ray energy dispersive spectroscopy (EDX). Leachability studies on solidified bricks were carried out to determine the metal fixation and dissolved organic (as COD) concentration in the leachate.

  9. [Physical and chemical stability of fortified ophtalmic ready-to-use solutions: review of literature].

    Science.gov (United States)

    Sourdeau, P; Evrard, J-M; Remy, G; Hecq, J-D

    2012-03-01

    Ophtalmic infections and inflammations are often encountered during hospitalization. They require the preparation of "fortified" ophtalmic solutions, i.e. pharmaceutical ophtalmic solutions which are hyperconcentrated in active substance. The data of physicochemical stabilities are modified and it is therefore essential to gather the results of the various publications devoted to this subject. In 2006, an initial literature review was undertaken to identify the molecules mostly used in the preparation of fortified ophtalmic solutions in hospital. A second review of the literature in 2010 has enriched the knowledge about it. Two new drugs have entered the summary table: amikacin and ticarcillin disodium. Date on 12 molecules already known in 2006 were updated to improve clinical practices. A review of the literature was undertaken in order to collect the results of the molecules mostly used for the preparation of the fortified ophtalmic solutions in hospitals. A summary table, indicating the active substance, its concentration, the assay method, the storage temperature and physicochemical modifications, presents all the results. This review of literature makes it possible to match stability and validity period to these preparations. Copyright © 2011 Elsevier Masson SAS. All rights reserved.

  10. Swelling, Mechanics, and Thermal/Chemical Stability of Hydrogels Containing Phenylboronic Acid Side Chains

    Directory of Open Access Journals (Sweden)

    Arum Kim

    2017-12-01

    Full Text Available We report here studies of swelling, mechanics, and thermal stability of hydrogels consisting of 20 mol % methacrylamidophenylboronic acid (MPBA and 80 mol % acrylamide (AAm, lightly crosslinked with methylenebisacrylamide (Bis. Swelling was measured in solutions of fixed ionic strength, but with varying pH values and fructose concentrations. Mechanics was studied by compression and hold. In the absence of sugar or in the presence of fructose, the modulus was mostly maintained during the hold period, while a significant stress relaxation was seen in the presence of glucose, consistent with reversible, dynamic crosslinks provided by glucose, but not fructose. Thermal stability was determined by incubating hydrogels at pH 7.4 at room temperature, and 37, 50, and 65 °C, and monitoring swelling. In PBS (phosphate buffered saline solutions containing 9 mM fructose, swelling remained essentially complete for 50 days at room temperature, but decreased substantially with time at the higher temperatures, with accelerated reduction of swelling with increasing temperature. Controls indicated that over long time periods, both the MPBA and AAm units were experiencing conversion to different species.

  11. Radiolabeled hydroxamate-based matrix metalloproteinase inhibitors: How chemical modifications affect pharmacokinetics and metabolic stability

    International Nuclear Information System (INIS)

    Hugenberg, Verena; Hermann, Sven; Galla, Fabian; Schäfers, Michael

    2016-01-01

    Introduction: Dysregulated MMP expression or activation is associated with several diseases. To study MMP activity in vivo by means of PET a radiolabeled MMP inhibitor (MMPI) functioning as radiotracer has been developed by our group based on the lead structure CGS 25966. Materials and methods: Aiming at the modification of the pharmacokinetics of this lipophilic model tracer a new class of MMPIs has been discovered, consisting of additional fluorinated hydrophilic substructures, such as mini-PEG and/or 1,2,3-triazole units. To identify the best candidate for further clinical applications, radiofluorinated compounds of each subgroup have been (radio) synthesized and evaluated regarding their biodistribution behavior and their metabolic stability. Results: Radiosyntheses of different triazole based MMPIs could be realized using two step “click chemistry” procedures. Compared to lead structure [ 18 F]FEtO-CGS 25966 ([ 18 F]1e, log D(exp) = 2.02, IC 50 = 2–50 nM) all selected candidates showed increased hydrophilicities and inhibition potencies (log D(exp) = 0.23–1.25, IC 50 = 0.006–6 nM). Interestingly, despite different hydrophilicities most triazole based MMPIs showed no significant differences in their in vivo biodistribution behavior and were cleared predominantly via the hepatobiliary excretion route. Biostability and metabolism studies in vitro and in vivo revealed significant higher metabolic stability for the triazole moiety compared to the benzyl ring in the lead structure. Cleavage of ethylene glycol subunits of the mini-PEG chain led to a faster metabolism of mini-PEG containing MMPIs. Conclusion: The introduction of hydrophilic groups such as mini-PEG and 1,2,3-triazole units did not lead to a significant shift of the hepatobiliary elimination towards renal clearance. Particularly the introduction of mini-PEG chains led to an intense metabolic decomposition. Substitution of the benzyl moiety in lead structure 1e by a 1,2,3-trizole ring resulted

  12. Chemical stability of insulin. 5. Isolation, characterization and identification of insulin transformation products.

    Science.gov (United States)

    Brange, J; Hallund, O; Sørensen, E

    1992-01-01

    During storage of insulin formulated for therapy, minor amounts of various degradation and covalent di- and polymerization products are formed [1-3]. The main chemical transformation products were isolated from aged preparations and characterized chemically and biologically. The most prominent products formed in neutral medium were identified as a mixture of deamidation products hydrolyzed at residue B3, namely isoAsp B3 and Asp B3 derivatives. A hydrolysis product formed only in crystals of insulin zinc suspensions containing a surplus of zinc ions in the supernatant was identified as an A8-A9 cleavage product. The small amounts of covalent insulin dimers (CID) formed in all formulations were shown to be a heterogenous mixture of 5-6 different CIDs with a composition dependent on the pharmaceutical formulation. The chemical characteristics of the CIDs indicate that they are formed through a transamidation reaction mainly between the B-chain N-terminal and one of the four amide side-chains of the A chain. GlnA15, AsnA18 and, in particular, AsnA21 participate in the formation of such isopeptide links between two insulin molecules. The covalent insulin-protamine products (CIPP) formed during storage of NPH preparations presumably originate from a similar reaction between the protamine N-terminal with an amide in insulin. Covalent polymerization products, mainly formed during storage of amorphously suspended insulin at higher temperature, were shown to be due to disulfide interactions. Biological in vivo potencies relative to native insulin were less than 2% for the split-(A8-A9)-product and for the covalent disulfide exchange polymers, 4% for the CIPP, approximately 15% for the CIDs, whereas the B3 derivatives exhibited full potency. Rabbit immunization experiments revealed that none of the insulin transformation products had significantly increased immunogenicity in rabbits.

  13. Chemical modifications and stability of diamond nanoparticles resolved by infrared spectroscopy and Kelvin force microscopy

    Czech Academy of Sciences Publication Activity Database

    Kozak, Halyna; Remeš, Zdeněk; Houdková, Jana; Stehlík, Štěpán; Kromka, Alexander; Rezek, Bohuslav

    2013-01-01

    Roč. 15, č. 4 (2013), "1568-1"-"1568-9" ISSN 1388-0764 R&D Projects: GA ČR GAP108/12/0910; GA ČR GPP205/12/P331; GA MŠk LH12186 Institutional support: RVO:68378271 Keywords : diamond nanoparticles * chemical modification * GAR-FTIR * AFM * KFM * XPS Subject RIV: BH - Optics, Masers, Lasers Impact factor: 2.278, year: 2013 http://link.springer.com/article/10.1007%2Fs11051-013-1568-7

  14. Photo- and radiation-chemical stability of molecules. Reactions of monomolecular hydrogen atom splitting off

    International Nuclear Information System (INIS)

    Plotnikov, V.G.; Ovchinnikov, A.A.

    1978-01-01

    In the review of works published up to 1978 one of the main problems of radiation chemistry is discussed, namely the relationship between the structure of organic molecules and their resistance to the effect of ionizing radiation. Theoretical aspects of this problem are considered for reactions of monomolecular hydrogen atom splitting off. It is shown that the radical yield in low-temperature radiation-chemical experiments is connected with the position of lower triplet states of molecules, ionization potentials, polarity of medium and the energy of C-H bonds in cation radicals

  15. Comparative study on the freeze stability of yeast and chemical leavened steamed bread dough.

    Science.gov (United States)

    Wang, Pei; Yang, Runqiang; Gu, Zhenxin; Xu, Xueming; Jin, Zhengyu

    2017-04-15

    The present study comparatively evaluated the evolution of yeast and chemical leavened steamed bread dough (YLD/CLD) quality during freeze/thaw (FT) cycles. The steamed bread quality of CLD was more freeze-stable than that of the YLD after 3 FT cycles. Decreased yeast viability contributed to the loss of gassing power in YLD while no significant differences were observed for CLD during FT cycles. However, faster gas release rate in frozen CLD indicated gas retention loss due to the distortion of gluten network. Glutenin macropolymers (GMP) depolymerization via breakage of inter-chain disulfide (SS) bonds and conversions of α-helix and β-turn to β-sheet structures were the main indicators of gluten deterioration. Gluten network was more vulnerable in frozen YLD, resulting in detectable loss of viscoelasticity. The results suggested that supplement of chemical leavener contributed to a more freeze-tolerant gluten network besides its stable gassing power. Copyright © 2016 Elsevier Ltd. All rights reserved.

  16. Chemical Stability Investigations of Polyisobutylene as New Binder for Application in Lithium Air-Batteries

    International Nuclear Information System (INIS)

    Heine, Jennifer; Rodehorst, Uta; Badillo, Juan Pablo; Winter, Martin; Bieker, Peter

    2015-01-01

    ABSTRACT: The side reactions of LiO 2 , Li 2 O 2 and Li 2 O, formed during the discharge process at the cathode/electrolyte interphase, are still a main challenge of lithium-air batteries. During these reactions, polyvinylidene difluoride (PVdF), as the commonly used cathode binder material, is decomposing, leading to a shorter lifetime of the battery. In this paper, we introduced and investigated polyisobutylene (PIB), a chemically and electrochemically inert polymeric material, to substitute PVdF as binder for lithium-air batteries. Results obtained by X-ray diffraction and spectroscopic methods showed, that PIB is far more stable in the presence of O 2 − , O 2 2− as well as O 2− species compared to PVdF. This distinct inertness makes PIB a promising binder for lithium-air batteries

  17. Physico-chemical stability of busulfan in injectable solutions in various administration packages.

    Science.gov (United States)

    Houot, Mélanie; Poinsignon, Vianney; Mercier, Lionel; Valade, Cyril; Desmaris, Romain; Lemare, François; Paci, Angelo

    2013-03-01

    Busulfan is used as part of a conditioning regimen prior to hematopoietic stem cell transplantation for the treatment of certain cancers and immune deficiency syndromes. Due to its instability in aqueous preparations, busulfan for infusion is prepared from a concentrate and has a relatively short shelf life once prepared. The purpose of this study was to identify the most suitable storage container and temperature to maximize the shelf life of busulfan therapeutic infusions prepared from Busilvex(®). Busilvex(®) 6 mg/mL was diluted to 0.55 mg/mL with 0.9 % NaCl and aliquots dispensed into polypropylene syringes, polyvinyl chloride bags, and glass bottles. Three storage temperatures were evaluated: 2-8 °C, 13-15 °C (thermostatically controlled chamber), and room temperature (20 ± 5 °C). At set time points, samples were analysed for busulfan content, using a high-performance liquid chromatography (HPLC) system with ultraviolet detection. The change in pH and osmolarity on storage was also determined, and solutions were inspected visually for formation of a precipitate or colour change. To determine the contribution of precipitation to loss of busulfan content on storage, samples from one time series were treated with the solvent dimethylacetamide prior to HPLC separation and quantitation of busulfan. The results of the active substance content monitoring study over a 48-h period demonstrate that busulfan solution is stable at a 5 % threshold, at 2-8 °C for 16 h in syringes, 14 h in glass bottles, and 6 h in bags. In addition, the period of stability decreases as the temperature increases (4 h at 20 ± 5 °C). The solution is considered to be stable, subject to precipitation liable to be observed regardless of the temperature. The best stability was observed for busulfan solutions placed at 2-8 °C in syringes. This study demonstrated that precipitation, in addition to hydrolysis, has a significant influence on the busulfan content.

  18. Chemical stability of soda-alumina-zirconia-silica glasses to Na, Na2S4, and S

    International Nuclear Information System (INIS)

    Bloom, S.I.; Bradley, J.; Nelson, P.A.; Roche, M.F.

    1985-01-01

    Twenty-two glasses with a broad range of compositions, spanning the quaternary soda-alumina-zirconia-silica system, have been prepared to allow characterization of the various properties of the system. The glasses were characterized by their resistivities, energies of activation for conduction, and glass transition temperatures. The glasses were screened for compositions of especially high chemical stability of static corrosion tests in Na, S, and Na 2 S 4 for 1000h at 400 0 C. Among the glasses tested, the high soda glasses showed the smallest weight change after exposure to the three media. The weight change observed was comparable to that seen in the Dow borate glass and beta'' alumina

  19. Assessment of chemical and biochemical stabilization of organic C in soils from the long-term experiments at Rothamsted (UK).

    Science.gov (United States)

    De Nobili, M; Contin, M; Mahieu, N; Randall, E W; Brookes, P C

    2008-01-01

    Biological and chemical stabilization of organic C was assessed in soils sampled from the long-term experiments at Rothamsted (UK), representing a wide range of carbon inputs and managements by extracting labile, non-humified organic matter (NH) and humic substances (HS). Four sequentially extracted humic substances fractions of soil organic matter (SOM) were extracted and characterized before and after a 215-day laboratory incubation at 25 degrees C from two arable soils, a woodland soil and an occasionally stubbed soil. The fractions corresponded to biochemically stabilised SOM extracted in 0.5M NaOH (free fulvic acids (FA) and humic acids (HA)) and chemically plus biochemically stabilised SOM extracted from the residue with 0.1M Na4P2O7 plus 0.1M NaOH (bound FA and HA). Our aim was to investigate the effects of chemical and biochemical stabilization on carbon sequestration. The non-humic to humic (NH/H) C ratio separated the soils into two distinct groups: arable soils (unless fertilised with farmyard manure) had an NH/H C ratio between 1.05 and 0.71, about twice that of the other soils (0.51-0.26). During incubation a slow, but detectable, decrease in the NH/H C ratio occurred in soils of C input equivalent or lower to 4Mgha(-1)y(-1), whereas the ratio remained practically constant in the other soils. Before incubation the free to bound humic C ratio increased linearly (R2=0.91) with C inputs in the soils from the Broadbalk experiment and decreased during incubation, showing that biochemical stabilization is less effective than chemical stabilization in preserving humic C. Changes in delta13C and delta15N after incubation were confined to the free FA fractions. The delta13C of free FA increased by 1.48 and 0.80 per thousand, respectively, in the stubbed and woodland soils, indicating a progressive biological transformation. On the contrary, a decrease was observed for the bound FA of both soils. Concomitantly, a Deltadelta15N of up to +3.52 per thousand was

  20. 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, CaSiO 3 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 CaSiO 3 ceramic (Ca 11 Si 4 B 2 O 22 , 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 CaSiO 3 (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 Ca 11 Si 4 B 2 O 22 coatings possess excellent osteogenic activity and might be a promising candidate for orthopedic applications.

  1. Chemical stability of the fiber coating/matrix interface in silicon-based ceramic matrix composites

    International Nuclear Information System (INIS)

    Lee, K.N.; Jacobson, N.S.

    1995-01-01

    Carbon and boron nitride are used as fiber coatings in silicon-based composites. In order to assess the long-term stability of these materials, reactions of carbon/Si 3 N 4 and BN/SiC were studied at high temperatures with Knudsen effusion, coupon tests, and by microstructural examination. in the carbon/Si 3 N 4 system, carbon reacted with Si 3 N 4 to form gaseous N 2 and SiC. The formation of SiC limited further reaction by physically separating the carbon and Si 3 N 4 . Consequently, the development of high p(N 2 ) at the interface, predicted from thermochemical calculations, did not occur, thus limiting the potential deleterious effects of the reaction on the composite. Strong indications of a reaction between BN and SiC were shown by TEM and SIMS analysis of the BN/SiC interface. In long-term exposures, this reaction can lead to a depletion of a BN coating and/or an unfavorable change of the interfacial properties, limiting the beneficial effects of the coating

  2. CHEMICAL STABILITY OF COTTONSEED AND GROUNDNUT OIL USED FOR FRYING BHAJIAS AND ITS SENSORY QUALITIES

    Directory of Open Access Journals (Sweden)

    Ashima Gupta

    2014-12-01

    Full Text Available Deep fried snacks, which evolved as snacks between meals include bhajia, samosa, etc are very popular in India and commercially exploited on a wide scale.Cottonseed and Groundnut oil frequently used in Gujarat for cooking purpose studied for its intermittent frying stability. Indian fried snack popularly known as ‘Bhajia’ fried for 5 min at an interval of 1 h; 5 times a day for 5 consecutive days and studied for its various sensory attributes using 9-point hedonic scale. Standard AOCS and AOAC methods were used to determine the quality of oil. Peroxide and p-anisidine values of both oils increased significantly p<0.001 during the 25 h of intermittent frying. Iodine value of cottonseed oil did not decrease throughout the intermittent frying period. Polar components increased 257.5% in cottonseed oil (CSO and 142.9% in groundnut oil (GNO.The saturated and monounsaturated fatty acid content increased significantly with the increase in frying hours.No significant change was seen in linoleic/palmitic acid ratio of both the oils during bhajias frying. The sensory qualities of bhajia fried at different intervals did not change significantly for various attributes namely flavor, taste, crispness, greasiness, odor, color, appearance and overall acceptability.

  3. PHYSICO-CHEMICAL PHENOMENA IN SOIL STABILIZATION FOR ROADS OR HIGHWAYS INFRASTRUCTURES

    Directory of Open Access Journals (Sweden)

    Anghel STANCIU

    2013-11-01

    Full Text Available Reducing the impact on the environment of constructing transportation infrastructures can be achieved through reusing or recycling certain materials. In this context, the current trend is to use materials that do not have a negative impact on the environment and provide a long term solution. Such local materials for the construction of transportation infrastructure are the active clays. This paper presents the physicochemical and mineralogical structure of clays and their behavior regarding the interaction with water. A negative effect of this interaction is the swelling, the contraction and, respectively, the swell pressure. These produce effects (fissures, cracks in the structure of roads, highways and, respectively, airport runways. The authors analyze the possibility to reduce these effects by clay stabilization with mineral binders (cement, lime. Results on lime mixtures testing are presented in terms of physical and mechanical properties, and optimum percentages of the mixtures are presented. It is also concluded that this solution is more cost-effective than the classical one as replacing the clay layer from the roadbed with other filling materials transported from other areas.

  4. Evaluation of Chemical Characterization, Antioxidant Activity and Oxidative Stability of Some Waste Seed Oil

    Directory of Open Access Journals (Sweden)

    Sibel Uluata

    2017-01-01

    Full Text Available In this study, fatty acid composition, antioxidant activity, total phenolic compounds (TPC and oxidative stability of cherry seed (SCO, sweet cherry seed (SCSO, mulberry seed (MSO and plum seed oil (PSO were determined. Oleic acid was determined as primary fatty acid (42.9-67.3%, and followed by linoleic acid (23.4-41.8% for SCO, SCSO and PSO. Linoleic acid was determined as primary fatty acid in MSO. γ-tocopherol was determined the main and highest tocopherol isomers varied from 579.9 to 605 mg/kg oil in SCO, SCSO and PSO, whereas δ-tocopherol was determined main tocopherol isomer with 1354mg/kg oil value in MSO. Plum seed oil (PSO was the highest antioxidant activity values in both 2,2-diphenyl-1-picrylhydrazyl (DPPH and 2,2'-azino-bis-(3-ethylbenzthiazoline-6-sulfonic acid (ABTS assays. There was no significant differences in lipid hydroperoxide and TBARS (2-thiobarbituric acid-reactive substance formation among SCO, SCSO and MSO. PSO had the highest induction period (15.1 h, followed by MSO (1.4 h, SCSO (1.5 h, SCO(1.3 h. PSO was oxidatively more stable than the other oil samples. This research shows that these waste seed oils have high antioxidant capacity and tocopherol content, so they could be used in food industry.

  5. Amorphous nano-curcumin stabilized oil in water emulsion: Physico chemical characterization.

    Science.gov (United States)

    Aditya, N P; Hamilton, Ian E; Norton, Ian T

    2017-06-01

    Particle characteristics e.g. size and polymorphism are known to significantly affect the Pickering ability of the solid particles by influencing their interaction at the oil and water (O/W) interface. In this study, nano-sized amorphous curcumin particles were fabricated using nanonization technology to use them as Pickering particles. After nanonization, native crystalline curcumin particles were converted into amorphous, nanosized particles of ∼220nm. Amorphous nature of the particle was evident from the decreased melting point from 177±1°C (native curcumin) to 146±3°C (nanonized curcumin) and enthalpy from 27±2J/g to 3.5±1J/g. Interfacial tension (IFT) studies have shown a decrease in IFT at the O/W interface from ∼27mN/m to ∼15mN/m in the presence of amorphous curcumin particles in water phase compared to crystalline curcumin particles. Curcumin stabilized O/W emulsion has an initial droplet size of ∼1.2μm and they were stable for 30days at 4°C. Copyright © 2016 Elsevier Ltd. All rights reserved.

  6. An investigation of the chemical stability of a monomer/polymer gel dosimeter

    International Nuclear Information System (INIS)

    De Deene, Y.; De Wagter, C.; De Neve, W.; Achten, E.

    2000-01-01

    The aim of this work is to investigate the temporal stability of a polyacrylamide gelatin hydrogel used for 3D monomer/polymer gel dosimetry techniques involving different methods of analysis. Long-term instabilities for a similar gel have recently been reported, but differ markedly from those described in this work. Two kinds of long-term instabilities are described. One affects the slope of the dose-R 2 plot and is related to post-irradiation polymerization of the comonomer/polymer aggregates. It is observed that post-irradiation polymerization only lasts 12 hours after irradiation. The other instability affects the intercept of the dose-R 2 plot, lasts for up to 30 days and is related to the gelation process of gelatin. Further studies were performed on gelatin gels of varying compositions to obtain a better understanding of the molecular mechanism that causes the instability due to gelation. The studies included observations of the spin-spin and spin-lattice relaxation rates in combination with diffusion measurements and optical measurements. It is shown that the heating history during the manufacture of the gel affects the absolute R 2 value of the gel but not its variation. The findings presented in this study may help in producing more stable and reproducible monomer/polymer gel dosimeters. (author)

  7. Wet Chemical Oxidation and Stabilization of Mixed and Low Level Organic Wastes

    International Nuclear Information System (INIS)

    Pierce, R.A.; Livingston, R.R.; Burge, D.A.; Ramsey, W.G.

    1998-03-01

    Mixed acid oxidation is a non-incineration process capable of destroying organic compounds, including papers, plastics, resins, and oils, at moderate temperatures and pressures. The technology, developed at the Savannah River Site, uses a mixture of an oxidant (nitric acid) and a carrier acid (phosphoric acid). The carrier acid acts as a holding medium which allows appreciable amounts of the oxidant to be retained in solution at atmospheric pressure and at the temperatures needed for oxidation. The phosphoric acid also provides the raw materials for making a final waste which contains the metal contaminants from the waste stream. Savannah River has designed, built, and started up a 40-liter pilot reaction vessel to demonstrate the process and its sub-systems on a larger scale than earlier testing. The unit has been demonstrated and has provided important data on the operation of the oxidation and acid recovery systems. Specific results will be presented on oxidation conditions, acid recovery efficiency, chloride removal, metal retention, and process monitoring. Additional studies have been conducted with a smaller vessel in a radioactive hood. Testing with plutonium-bearing waste simulants was performed to make preliminary predictions about the behavior of plutonium in the process. Samples of the remaining phosphoric acid from these tests has been converted to two separate final forms for analysis. Results will be presented on plutonium fractionation during the oxidation process and waste form stability

  8. Chemical Stability of the Fiber Coating/Matrix Interface in Silicon-Based Ceramic Matrix Composites

    Science.gov (United States)

    Lee, Kang N.; Jacobson, Nathan S.

    1995-01-01

    Carbon and boron nitride are used as fiber coatings in silicon-based composites. In order to assess the long-term stability of these materials, reactions of carbon/Si3N4 and BN/SiC were studied at high temperatures with Knudsen effusion, coupon tests, and microstructural examination. In the carbon/Si3N4 system, carbon reacted with Si3N4 to form gaseous N2 and SiC. The formation of SiC limited further reaction by physically separating the carbon and Si3N4. Consequently, the development of high p(N2) at the interface, predicted from thermochemical calculations, did not occur, thus limiting the potential deleterious effects of the reaction on the composite. Strong indications of a reaction between BN and SiC were shown by TEM and SIMS analysis of the BN/SiC interface. In long-term exposures, this reaction can lead to a depletion of a BN coating and/or an unfavorable change of the interfacial properties, limiting the beneficial effects of the coating.

  9. Obtaining Highly Crystalline Barium Sulphate Nanoparticles via Chemical Precipitation and Quenching in Absence of Polymer Stabilizers

    Directory of Open Access Journals (Sweden)

    Ángela B. Sifontes

    2015-01-01

    Full Text Available Here we report the synthesis of barium sulphate (BaSO4 nanoparticles from Ba(OH2/BaCl2 solutions by a combined method of precipitation and quenching in absence of polymer stabilizers. Transmission electron microscopy (HRTEM, Fourier transforms infrared spectroscopy (FTIR, and X-ray diffraction (XRD were employed to characterize the particles. The Scherrer formula was applied to estimate the particle size using the width of the diffraction peaks. The obtained results indicate that the synthesized material is mainly composed of nanocrystalline barite, with nearly spherical morphology, and diameters ranging from 4 to 92 nm. The lattice images of nanoparticles were clearly observed by HRTEM, indicating a high degree of crystallinity and phase purity. In addition, agglomerates with diameters between 20 and 300 nm were observed in both lattice images and dynamic light scattering measurements. The latter allowed obtaining the particle size distribution, the evolution of the aggregate size in time of BaSO4 in aqueous solutions, and the sedimentation rate of these solutions from turbidimetry measurements. A short discussion on the possible medical applications is presented.

  10. HR-EELS study of hydrogen bonding configuration, chemical and thermal stability of detonation nanodiamond films

    Energy Technology Data Exchange (ETDEWEB)

    Michaelson, Sh.; Akhvlediani, R. [Schulich Faculty of Chemistry, Technion-Israel Institute of Technology, Haifa 32000 (Israel); Petit, T.; Girard, H.A.; Arnault, J.C. [CEA, LIST, Diamond Sensors Laboratory, F-91191 Gif sur Yvette (France); Hoffman, A., E-mail: choffman@tx.technion.ac.il [Schulich Faculty of Chemistry, Technion-Israel Institute of Technology, Haifa 32000 (Israel)

    2014-06-01

    Nano-diamond films composed of 3–10 nm grains prepared by the detonation method and deposited onto silicon substrates by drop-casting were examined by high resolution electron energy loss spectroscopy (HR-EELS), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and secondary ion mass spectroscopy (SIMS). The impact of (i) ex-situ ambient annealing at 400 °C and (ii) ex-situ hydrogenation on hydrogen bonding and its thermal stability were examined. In order to clarify the changes in hydrogen bonding configuration detected on the different surfaces as a function of thermal annealing, in-situ hydrogenation by thermally activated atomic hydrogen was performed and examined. This study provides direct evidence that the exposure to ambient conditions and medium temperature ambient annealing have a pronounced effect on the hydrogen-carbon bonding configuration onto the nano-diamond surfaces. In-situ 1000 °C annealing results in irreversible changes of the film surface and partial nano-diamond silicidation.

  11. Understanding chemical-potential-related transient pore-pressure response to improve real-time borehole (in)stability predictions

    Energy Technology Data Exchange (ETDEWEB)

    Tare, U.A.; Mody, F.K.; Mese, A.I. [Halliburton Energy Services, Cairo (Egypt)

    2000-11-01

    Experimental studies were conducted to explain the concept of a real-time wellbore (in)stability logging methodology. The role of the chemical potential of drilling fluids on transient pore pressure and time-dependent rock property alterations of shale formations was examined by providing details about a pore pressure transmission (PPT) test. The PPT experiments exposed formation (shale) cores under simulated downhole conditions to various salt solutions and drilling fluids. The main objective was to translate the results of the PPT tests to actual drilling conditions. A 20 per cent w/w calcium chloride solution was exposed to a Pierre II shale under high pressure in the PPT apparatus. The PPT test was used to estimate the impact of a drilling fluid on shale pore pressure. The efficiency of the salt solution/shale system was also estimated. Estimates of the dynamic rock properties were made based on the obtained acoustic data. It was determined that in order to accurately model time-dependent wellbore (in)stability in the field, it is important to calibrate representative shale core response to drilling fluids under realistic in-situ conditions. The 20 per cent w/w calcium chloride solution showed very low membrane efficiency of 4.45 per cent. It was concluded that changes in the shale dynamic rock properties as a function of test fluid exposure can be obtained from the simultaneous acquisition of sonic compression and shear wave velocity data. 12 refs., 5 figs.

  12. Chemical stability study of vitamins thiamine, riboflavin, pyridoxine and ascorbic acid in parenteral nutrition for neonatal use

    Science.gov (United States)

    2011-01-01

    Background The objective of this work was to study the vitamins B1, B2, B6 and C stability in a pediatric formulation containing high amounts of calcium in the presence of organic phosphate, amino acids, glucose, sodium chloride, magnesium sulfate, pediatric vitamins and trace elements under different conditions using developed and validated analytical methods. Methods The study was carried out during 72 h with formulations packaged in recommended storage temperature (4°C) and 25°C, with and without photoprotection. Results The results showed that the methodologies used for assessing the chemical stability of vitamins B1, B2, B6 and C in the formulation were selective, linear, precise and accurate. The vitamins could be considered stable in the formulation during the three days of study if stored at 4°C. When stored at 25°C vitamin C presented instability after 48 h. Conclusion The pediatric formulation containing high amount of calcium in the presence of organic phosphate, amino acids, glucose, sodium chloride, magnesium sulphate, pediatric vitamins and trace elements packaged in bag-type trilaminate presented a shelf life of the 72 h, when maintained under refrigeration, between 2°C and 8°C. This shelf life was measured considering the vitamins studied. Further studies are needed including all the vitamins present in this formulation. PMID:21569609

  13. Chemical stability study of vitamins thiamine, riboflavin, pyridoxine and ascorbic acid in parenteral nutrition for neonatal use

    Directory of Open Access Journals (Sweden)

    Cabral Lúcio M

    2011-05-01

    Full Text Available Abstract Background The objective of this work was to study the vitamins B1, B2, B6 and C stability in a pediatric formulation containing high amounts of calcium in the presence of organic phosphate, amino acids, glucose, sodium chloride, magnesium sulfate, pediatric vitamins and trace elements under different conditions using developed and validated analytical methods. Methods The study was carried out during 72 h with formulations packaged in recommended storage temperature (4°C and 25°C, with and without photoprotection. Results The results showed that the methodologies used for assessing the chemical stability of vitamins B1, B2, B6 and C in the formulation were selective, linear, precise and accurate. The vitamins could be considered stable in the formulation during the three days of study if stored at 4°C. When stored at 25°C vitamin C presented instability after 48 h. Conclusion The pediatric formulation containing high amount of calcium in the presence of organic phosphate, amino acids, glucose, sodium chloride, magnesium sulphate, pediatric vitamins and trace elements packaged in bag-type trilaminate presented a shelf life of the 72 h, when maintained under refrigeration, between 2°C and 8°C. This shelf life was measured considering the vitamins studied. Further studies are needed including all the vitamins present in this formulation.

  14. Chemical Synthesis of Porous Barium Titanate Thin Film and Thermal Stabilization of Ferroelectric Phase by Porosity-Induced Strain.

    Science.gov (United States)

    Suzuki, Norihiro; Osada, Minoru; Billah, Motasim; Bando, Yoshio; Yamauchi, Yusuke; Hossain, Shahriar A

    2018-03-27

    Barium titanate (BaTiO3, hereafter BT) is an established ferroelectric material first discovered in the 1940s and still widely used because of its well-balanced ferroelectricity, piezoelectricity, and dielectric constant. In addition, BT does not contain any toxic elements. Therefore, it is considered to be an eco-friendly material, which has attracted considerable interest as a replacement for lead zirconate titanate (PZT). However, bulk BT loses its ferroelectricity at approximately 130 °C, thus, it cannot be used at high temperatures. Because of the growing demand for high-temperature ferroelectric materials, it is important to enhance the thermal stability of ferroelectricity in BT. In previous studies, strain originating from the lattice mismatch at hetero-interfaces has been used. However, the sample preparation in this approach requires complicated and expensive physical processes, which are undesirable for practical applications. In this study, we propose a chemical synthesis of a porous material as an alternative means of introducing strain. We synthesized a porous BT thin film using a surfactant-assisted sol-gel method, in which self-assembled amphipathic surfactant micelles were used as an organic template. Through a series of studies, we clarified that the introduction of pores had a similar effect on distorting the BT crystal lattice, to that of a hetero-interface, leading to the enhancement and stabilization of ferroelectricity. Owing to its simplicity and cost effectiveness, this fabrication process has considerable advantages over conventional methods.

  15. Effect of impregnation of ZrO2 on the chemical stability and the superconductivity of Y- and Bi-systems

    International Nuclear Information System (INIS)

    Muroya, Masaaki; Minamiyama, Hideaki

    1994-01-01

    The results are given concerning the influence of impregnation of Zr on chemical stability and superconductivity of YBa 2 (Cu 1-x · Zr x ) 3 O 7-y (123-system) and Bi 1.84 Zr x Pb 0.34 Sr 1.91 Ca 2.03 Cu 3.06 O y (2223-system) superconductors, when the samples are contacted with the solutions of acid (pH3), distilled water (pH5.6) and base (pH9), where x = 0-0.35. It is concluded that the low chemical stability was found in the case of YBZCO, barium hydroxide and/or barium carbonate were precipitated into the solutions, even though mechanical strength was increased by impregnation of Zr, and the chemical stability of Bi-system is high compared with that of the Y-system. 8 refs., 5 figs

  16. Chemical Composition and Storage Stability of Beef burger Steaks as Influenced by Cooking and Irradiation

    International Nuclear Information System (INIS)

    Tawfik, S.S.; El kabbani, H.M.; Sallam, M.H.; Attia, A.I.

    2007-01-01

    Meat industry in Egypt has a great economic potential, but till now it has not received adequate attention. Beef burgers were prepared (50 g, 1 cm thick steaks) and aerobically packaged into polyethylene pages then divided into control, cooking and gamma-irradiated (3 and 4 kGy) groups. Samples stored at (5±degree c) and periodically judged after 5, 10, 15, 20,25 and 30 days. The results showed that irradiation increased the shelf life of stored cooked beef burger, as compared to control samples. In addition, the dose of 3 kGy is considered the most adequate for irradiation of this meat product because it obtained the same results reflected by 4 kGy. The microbiological, chemical and sensorial testing for stored cooking and irradiated beef burger steaks were examined according an experimental design presented conditions that were adequate for human consumption of this product during the refrigeration storage periods. For the non-irradiated beef burger samples, bacterial contamination was the main limiting factor with respect to the shelf life, whereas for the irradiated beef burger samples this factor was lipid oxidation. Conclusion: The cooking before food irradiation may be of practical efficacy in enhancing the technical effectiveness and feasibility of irradiation of a variety of meat products. Recommendation: The necessity for a proper preservation method for marketing the processing beef burger steaks in each of its numerous retail markets should be established central irradiation units for processing and packing before distribution in these retail markets

  17. Electronic parameters and top surface chemical stability of RbPb{sub 2}Br{sub 5}

    Energy Technology Data Exchange (ETDEWEB)

    Atuchin, V.V., E-mail: atuchin@thermo.isp.nsc.ru [Laboratory of Optical Materials and Structures, Institute of Semiconductor Physics, SB RAS, Novosibirsk 90, 630090 (Russian Federation); Isaenko, L.I. [Laboratory of Crystal Growth, Institute of Geology and Mineralogy, SB RAS, Novosibirsk 90, 630090 (Russian Federation); Kesler, V.G. [Laboratory of Physical Principles for Integrated Microelectronics, Institute of Semiconductor Physics, SB RAS, Novosibirsk 90, 630090 (Russian Federation); Pokrovsky, L.D. [Laboratory of Optical Materials and Structures, Institute of Semiconductor Physics, SB RAS, Novosibirsk 90, 630090 (Russian Federation); Tarasova, A.Yu. [Laboratory of Crystal Growth, Institute of Geology and Mineralogy, SB RAS, Novosibirsk 90, 630090 (Russian Federation)

    2012-01-16

    Highlights: Black-Right-Pointing-Pointer Bridgman growth of RbPb{sub 2}Br{sub 5} crystal. Black-Right-Pointing-Pointer Electronic structure measurements with XPS. Black-Right-Pointing-Pointer Optical crystalline surface fabrication. - Abstract: The RbPb{sub 2}Br{sub 5} crystal has been grown by Bridgman method. The electronic structure of RbPb{sub 2}Br{sub 5} has been measured with XPS for a powder sample. High chemical stability of RbPb{sub 2}Br{sub 5} surface is verified by weak intensity of O 1s core level recorded by XPS and structural RHEED measurements. Chemical bonding effects have been observed by the comparative analysis of element core levels and crystal structure of RbPb{sub 2}Br{sub 5} and several rubidium- and lead-containing bromides using binding energy difference parameters {Delta}{sub Rb} = (BE Rb 3d - BE Br 3d) and {Delta}{sub Pb} = (BE Pb 4f{sub 7/2} - BE Br 3d).

  18. Optimization of Bicomponent Electrospun Fibers for Therapeutic Use: Post-Treatments to Improve Chemical and Biological Stability

    Directory of Open Access Journals (Sweden)

    Antonio Papa

    2017-10-01

    Full Text Available Bicomponent electrospun nanofibers based on the combination of synthetic (i.e., aliphatic polyesters such as polycaprolactone (PCL and natural proteins (i.e., gelatin have been extensively investigated as temporary platforms to instruct cells by the release of molecular/pharmaceutical signals for the regeneration of several tissues. Here, water soluble proteins (i.e., gelatin, strictly embedded to PCL, act as carriers of bioactive molecules, thus improving bioavailability and supporting cell activities during in vitro regeneration. However, these proteins are rapidly digested by enzymes, locally produced by many different cell types, both in vitro and in vivo, with significant drawbacks in the control of molecular release. Hence, we have investigated three post-processing strategies based on the use of different crosslinking agents—(1-ethyl-3-(3-dimethylaminopropylcarbodiimide hydrochloride (EDC, glyceraldehyde (GC, and 1,4-butanediol diglycidyl ether (BDDGE—to delay the dissolution time of gelatin macromolecules from bicomponent fibers. All of the qualitative (i.e., SEM, TGA and quantitative (i.e., Trinitrobenzene sulfonate (TNBS and bicinchoninic acid (BCA assays morphological/chemical analyses as well as biocompatibility assays indicate that EDC crosslinking improves the chemical stability of bicomponent fibers at 37 °C and provides a more efficient encapsulation and controlled sustained release of drug, thus resulting in the best post-treatment to design bio-inspired fibrous platforms for the extended in vitro release of drugs.

  19. Thermal stability and chemical bonding states of AlOxNy/Si gate stacks revealed by synchrotron radiation photoemission spectroscopy

    International Nuclear Information System (INIS)

    He, G.; Toyoda, S.; Shimogaki, Y.; Oshima, M.

    2010-01-01

    Annealing-temperature dependence of the thermal stability and chemical bonding states of AlO x N y /SiO 2 /Si gate stacks grown by metalorganic chemical vapor deposition (MOCVD) using new chemistry was investigated by synchrotron radiation photoemission spectroscopy (SRPES). Results have confirmed the formation of the AlN and AlNO compounds in the as-deposited samples. Annealing the AlO x N y samples in N 2 ambient in 600-800 deg. C promotes the formation of SiO 2 component. Meanwhile, there is no formation of Al-O-Si and Al-Si binding states, suggesting no interdiffusion of Al with the Si substrate. A thermally induced reaction between Si and AlO x N y to form volatile SiO and Al 2 O is suggested to be responsible for the full disappearance of the Al component that accompanies annealing at annealing temperature of 1000 deg. C. The released N due to the breakage of the Al-N bonding will react with the SiO 2 interfacial layer and lead to the formation of the Si 3 -N-O/Si 2 -N-O components at the top of Si substrate. These results indicate high temperature processing induced evolution of the interfacial chemistry and application range of AlO x N y /Si gate stacks in future CMOS devices.

  20. Optimization of Bicomponent Electrospun Fibers for Therapeutic Use: Post-Treatments to Improve Chemical and Biological Stability.

    Science.gov (United States)

    Papa, Antonio; Guarino, Vincenzo; Cirillo, Valentina; Oliviero, Olimpia; Ambrosio, Luigi

    2017-10-16

    Bicomponent electrospun nanofibers based on the combination of synthetic (i.e., aliphatic polyesters such as polycaprolactone (PCL)) and natural proteins (i.e., gelatin) have been extensively investigated as temporary platforms to instruct cells by the release of molecular/pharmaceutical signals for the regeneration of several tissues. Here, water soluble proteins (i.e., gelatin), strictly embedded to PCL, act as carriers of bioactive molecules, thus improving bioavailability and supporting cell activities during in vitro regeneration. However, these proteins are rapidly digested by enzymes, locally produced by many different cell types, both in vitro and in vivo, with significant drawbacks in the control of molecular release. Hence, we have investigated three post-processing strategies based on the use of different crosslinking agents-(1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride) (EDC), glyceraldehyde (GC), and 1,4-butanediol diglycidyl ether (BDDGE)-to delay the dissolution time of gelatin macromolecules from bicomponent fibers. All of the qualitative (i.e., SEM, TGA) and quantitative (i.e., Trinitrobenzene sulfonate (TNBS) and bicinchoninic acid (BCA) assays) morphological/chemical analyses as well as biocompatibility assays indicate that EDC crosslinking improves the chemical stability of bicomponent fibers at 37 °C and provides a more efficient encapsulation and controlled sustained release of drug, thus resulting in the best post-treatment to design bio-inspired fibrous platforms for the extended in vitro release of drugs.

  1. Spinel-structured surface layers for facile Li ion transport and improved chemical stability of lithium manganese oxide spinel

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Hae Ri [Center for Energy Convergence Research, Korea Institute of Science Technology, Hwarang-ro 14-gil 5, Seongbuk-gu, Seoul 136-791 (Korea, Republic of); Department of Chemical and Biological Engineering, Korea University, 145, Anam-ro, Seongbuk-gu, Seoul 136-701 (Korea, Republic of); Seo, Hyo Ree; Lee, Boeun; Cho, Byung Won [Center for Energy Convergence Research, Korea Institute of Science Technology, Hwarang-ro 14-gil 5, Seongbuk-gu, Seoul 136-791 (Korea, Republic of); Lee, Kwan-Young [Department of Chemical and Biological Engineering, Korea University, 145, Anam-ro, Seongbuk-gu, Seoul 136-701 (Korea, Republic of); Oh, Si Hyoung, E-mail: sho74@kist.re.kr [Center for Energy Convergence Research, Korea Institute of Science Technology, Hwarang-ro 14-gil 5, Seongbuk-gu, Seoul 136-791 (Korea, Republic of)

    2017-01-15

    Graphical abstract: Strategically-designed spinel-structured nano-scale surface layer, LiM{sub x}Mn{sup IV}{sub 1−x}O{sub 4}, featuring a high Li{sup +} ion conductivity and a good chemical stability was applied on Al-doped LiMn{sub 2}O{sub 4} spinel for the drastic improvement of the electrochemical performance at the elevated temperature as a promising cathode material for lithium rechargeable batteries. - Highlights: • Spinel-structured surface layer with a high Li-ion conductivity and a good chemical stability was prepared. • Simple wet process was developed to apply nano-scale surface layer on aluminum doped lithium manganese oxide spinel. • The properties of nano-scale surface layer were characterized by analytical tools including GITT, HR-TEM and XAS. • Materials with surface coating layer exhibit an excellent electrochemical performance at the elevated temperature. - Abstract: Li-ion conducting spinel-structured oxide layer with a manganese oxidation state close to being tetravalent was prepared on aluminum-doped lithium manganese oxide spinel for improving the electrochemical performances at the elevated temperatures. This nanoscale surface layer provides a good ionic conduction path for lithium ion transport to the core and also serves as an excellent chemical barrier for protecting the high-capacity core material from manganese dissolution into the electrolyte. In this work, a simple wet process was employed to prepare thin LiAlMnO{sub 4} and LiMg{sub 0.5}Mn{sub 1.5}O{sub 4} layers on the surface of LiAl{sub 0.1}Mn{sub 1.9}O{sub 4}. X-ray absorption studies revealed an oxidation state close to tetravalent manganese on the surface layer of coated materials. Materials with these surface coating layers exhibited excellent capacity retentions superior to the bare material, without undermining the lithium ion transport characteristics and the high rate performances.

  2. Sensory and chemical stability in coated peanuts with the addition of essential oils and synthetic antioxidants

    Directory of Open Access Journals (Sweden)

    Olmedo, R. H.

    2012-03-01

    Full Text Available The objective of this work was to evaluate the antioxidant effect of essential oils on the oxidative stability of coated peanuts. Untreated coated peanuts (CP and treated coated peanuts with the addition of rosemary (CP-R, oregano (CP-O and laurel (CP-L essential oils and BHT (CPBHT were prepared. Peroxide values (PV and p-anisidine values (AV and the intensity ratings of sensory attributes by descriptive analysis were measured during 112 days of storage at room temperature (23°C. CP-BHT exhibited the lowest PV and AV increase. CP-R, CP-O and CP-L showed lower rates of increase in PV and AV than CP. The oxidized and cardboard flavor intensity ratings increased much more in CP during storage than the other studied products. CPBHT also showed the lowest increase in the intensity ratings of these sensory attributes. Three essential oils, namely, laurel, oregano and rosemary showed antioxidant activity and increased the shelf life of coated peanuts.

    El objetivo de este trabajo fue evaluar el efecto antioxidante de aceites esenciales sobre la estabilidad oxidativa en maní recubiertos. Se prepararon maníes recubiertos sin agregados (CP, y con el agregado de aceites esenciales de romero (CP-R, orégano (CP-O y laurel (CP-L y BHT (CPBHT. Se midieron, durante 112 días de almacenamiento, los valores de peróxidos (PV y p-anisidina (AV, y las intensidades de atributos sensoriales mediante análisis descriptivo. CP-BHT presentó el menor valor de PV y AV. CP-R, CP-O y CP-L tuvieron mayor PV y AV respecto a CP. Los valores de intensidad del sabor oxidado y cartón tuvieron un mayor incremento en CP durante el almacenamiento con respecto a los otros productos estudiados. La muestra CP-BHT también mostró los menores valores de intensidad de estos atributos sensoriales. Los aceites esenciales de laurel, orégano y romero presentaron actividad antioxidante e incrementaron la vida útil del maní recubierto.

  3. Chemical variation in a dominant tree species: population divergence, selection and genetic stability across environments.

    Directory of Open Access Journals (Sweden)

    Julianne M O'Reilly-Wapstra

    Full Text Available Understanding among and within population genetic variation of ecologically important plant traits provides insight into the potential evolutionary processes affecting those traits. The strength and consistency of selection driving variability in traits would be affected by plasticity in differences among genotypes across environments (G×E. We investigated population divergence, selection and environmental plasticity of foliar plant secondary metabolites (PSMs in a dominant tree species, Eucalyptus globulus. Using two common garden trials we examined variation in PSMs at multiple genetic scales; among 12 populations covering the full geographic range of the species and among up to 60 families within populations. Significant genetic variation in the expression of many PSMs resides both among and within populations of E. globulus with moderate (e.g., sideroxylonal A h(2op = 0.24 to high (e.g., macrocarpal G h(2op = 0.48 narrow sense heritabilities and high coefficients of additive genetic variation estimated for some compounds. A comparison of Qst and Fst estimates suggest that variability in some of these traits may be due to selection. Importantly, there was no genetic by environment interaction in the expression of any of the quantitative chemical traits despite often significant site effects. These results provide evidence that natural selection has contributed to population divergence in PSMs in E. globulus, and identifies the formylated phloroglucinol compounds (particularly sideroxylonal and a dominant oil, 1,8-cineole, as candidates for traits whose genetic architecture has been shaped by divergent selection. Additionally, as the genetic differences in these PSMs that influence community phenotypes is stable across environments, the role of plant genotype in structuring communities is strengthened and these genotypic differences may be relatively stable under global environmental changes.

  4. Greater autonomy at work

    NARCIS (Netherlands)

    Houtman, I.L.D.

    2004-01-01

    In the past 10 years, workers in the Netherlands increasingly report more decision-making power in their work. This is important for an economy in recession and where workers face greater work demands. It makes work more interesting, creates a healthier work environment, and provides opportunities

  5. CHEMICALS

    CERN Multimedia

    Medical Service

    2002-01-01

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

  6. Study on the chemical stability of catalyst counter electrodes for dye-sensitized solar cells using a simple X-ray photoelectron spectroscopy-based method

    Science.gov (United States)

    Yun, Dong-Jin; Kim, Jungmin; Chung, Jongwon; Park, SungHoon; Baek, WoonJoong; Kim, Yongsu; Kim, Seongheon; Kwon, Young-Nam; Chung, JaeGwan; Kyoung, Yongkoo; Kim, Ki-Hong; Heo, Sung

    2014-12-01

    Since the chemical/electrical stability and catalytic activity are essential conditions for catalyst counter electrodes (CCEs) in dye-sensitized solar cells (DSSCs), a simple dipping method is employed for evaluating the chemical stability of CCE candidates in an iodine-based liquid electrolyte (I-electrolyte). The chemical stabilities and transition mechanisms of the CCEs are successfully analyzed by studying the chemical transitions in X-ray photoelectron spectroscopy (XPS) core levels after dipping in the I-electrolyte. All films including the Pt film undergo degradation depending on the type of material. While dipping in the I-electrolyte, Cu and Au films scarcely dissolves as their respective metal sulfides, and the Al film gradually loss its metallic properties owing to Al2O3 growth. On the other hand, a previously unknown transition mechanism of organic conducting CCEs is determined based on the proposed method. Compared to the other metal films, the poly(3,4-ethylenedioxythiophene) poly(styrenesulfonate) (PEDOT:PSS) and multi wall carbon nanotube (MWCNT)/PEDOT:PSS films undergo an entirely unique transition mechanism, which results from the chemical adsorption of organic molecules onto PEDOT:PSS molecules in the I-electrolyte. Consequently, these chemical structure transitions correspond well to the degrees of alternation in the electrical properties of DSSCs with all the investigated CCEs.

  7. Heat, Acid and Chemically Induced Unfolding Pathways, Conformational Stability and Structure-Function Relationship in Wheat α-Amylase.

    Directory of Open Access Journals (Sweden)

    Kritika Singh

    Full Text Available Wheat α-amylase, a multi-domain protein with immense industrial applications, belongs to α+β class of proteins with native molecular mass of 32 kDa. In the present study, the pathways leading to denaturation and the relevant unfolded states of this multi-domain, robust enzyme from wheat were discerned under the influence of temperature, pH and chemical denaturants. The structural and functional aspects along with thermodynamic parameters for α-amylase unfolding were probed and analyzed using fluorescence, circular dichroism and enzyme assay methods. The enzyme exhibited remarkable stability up to 70°C with tendency to aggregate at higher temperature. Acid induced unfolding was also incomplete with respect to the structural content of the enzyme. Strong ANS binding at pH 2.0 suggested the existence of a partially unfolded intermediate state. The enzyme was structurally and functionally stable in the pH range 4.0-9.0 with 88% recovery of hydrolytic activity. Careful examination of biophysical properties of intermediate states populated in urea and GdHCl induced denaturation suggests that α-amylase unfolding undergoes irreversible and non-coincidental cooperative transitions, as opposed to previous reports of two-state unfolding. Our investigation highlights several structural features of the enzyme in relation to its catalytic activity. Since, α-amylase has been comprehensively exploited for use in a range of starch-based industries, in addition to its physiological significance in plants and animals, knowledge regarding its stability and folding aspects will promote its biotechnological applications.

  8. Chemical vapor deposition of three aminosilanes on silicon dioxide: surface characterization, stability, effects of silane concentration, and cyanine dye adsorption.

    Science.gov (United States)

    Zhang, Feng; Sautter, Ken; Larsen, Adam M; Findley, Daniel A; Davis, Robert C; Samha, Hussein; Linford, Matthew R

    2010-09-21

    Covalently bonded monolayers of two monofunctional aminosilanes (3-aminopropyldimethylethoxysilane, APDMES, and 3-aminopropyldiisopropylethoxysilane, APDIPES) and one trifunctional aminosilane (3-aminopropyltriethoxysilane, APTES) have been deposited on dehydrated silicon substrates by chemical vapor deposition (CVD) at 150 °C and low pressure (a few Torr) using reproducible equipment. Standard surface analytical techniques such as x-ray photoelectron spectroscopy (XPS), contact angle goniometry, spectroscopic ellipsometry, atomic force microscopy, and time-of-flight secondary ion mass spectroscopy (ToF-SIMS) have been employed to characterize the resulting films. These methods indicate that essentially constant surface coverages are obtained over a wide range of gas phase concentrations of the aminosilanes. XPS data further indicate that the N1s/Si2p ratio is higher after CVD with the trifunctional silane (APTES) compared to the monofunctional ones, with a higher N1s/Si2p ratio for APDMES compared to that for APDIPES. AFM images show an average surface roughness of 0.12- 0.15 nm among all three aminosilane films. Stability tests indicate that APDIPES films retain most of their integrity at pH 10 for several hours and are more stable than APTES or APDMES layers. The films also showed good stability against storage in the laboratory. ToF-SIMS of these samples showed expected peaks, such as CN(-), as well as CNO(-), which may arise from an interaction between monolayer amine groups and silanols. Optical absorption measurements on adsorbed cyanine dye at the surface of the aminosilane films show the formation of dimer aggregates on the surface. This is further supported by ellipsometry measurements. The concentration of dye on each surface appears to be consistent with the density of the amines.

  9. Physical-chemical characterization and stability study of alpha-trypsin at ph 3.0 by differential scanning calorimetry

    Energy Technology Data Exchange (ETDEWEB)

    Santos, A.M.C.; Santana, M.A.; Gomide, F.T.F.; Oliveira, J.S.; Vilas Boas, F.A.S.; Santoro, M.M.; Teixera, K.N. [Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, MG (Brazil). Inst. de Ciencias Biologicas (ICB). Dept. de Bioquimica e Imunologia; Miranda, A.A.C.; Biondi, I. [Universidade Estadual de Feira de Santana (UEFS), BA (Brazil). Dept. de Ciencias Biologicas; Vasconcelos, A.B.; Bemquerer, M.P. [EMBRAPA Recursos Geneticos e Biotecnologia, Brasilia, DF (Brazil). Parque Estacao Biologica (PqEB)

    2008-07-01

    Full text: {alpha}-Trypsin is a serine-protease with a polypeptide chain of 223 amino acid residues and six disulfide bridges. It is a globular protein with predominance of antiparallel {beta}-sheet secondary structure and it has two domains with similar structures. In the present work, a stability study of {alpha}-trypsin in the acid pH range was performed and physical-chemical denaturation parameters were measured by using differential scanning calorimetry (DSC). The {alpha}-trypsin has a shelf-life (t{sub 95%}) of about ten months at pH 3.0 and 4 deg C and its hydrolysis into the {psi}-trypsin isoform is negligible during six months as monitored by mass spectrometry (Micromass Q-ToF). The observed {delta}H{sub cal}/{delta}H{sub vH} ratio is close to unity for {alpha}-trypsin denaturation, which suggests the occurrence of a two-state transition, devoid of molten-globule intermediates. At pH 3.0, {alpha}-trypsin unfolded with T{sub m} 325.9 K and {delta}H= 99.10 kcal mol{sup -1}, and the change in heat capacity between the native and unfolded forms of the protein was estimated to be 1.96 {+-} 0.18 kcal mol{sup -1} K{sup -1}. The stability of {alpha}-trypsin calculated at 298 K and at pH 3.0 was {delta}G{sub U} = 6.10 kcal mol{sup -1}. These values are in the range expected for a small globular protein. These results show that the thermodynamic parameters for unfolding of {beta}-trypsin do not change substantially after its conversion to {alpha}-trypsin.

  10. Effect Of Chromium Nicotinate On Oxidative Stability, Chemical Composition And Meat Quality Of Growing-Finishing Pigs

    Directory of Open Access Journals (Sweden)

    Ondřej Bučko

    2015-12-01

    Full Text Available The effect of different organic sources of Cr on growth, feed efficiency and carcass value is known but there is a lack of information between chromium nicotinate (CrNic and pork quality. Therefore, purpose of this research was to investigate the effects of CrNic on chemical composition, quality and oxidative stability of pork meat. In the study, pigs of Large White breed (40 pcs were used. The pigs were divided into two groups, namely the control and the experimental of 20 pcs with equal number of barrows and gilts. The pigs were fed the same diet which consisted of three feed mixtures applied at the different growth phases, from 30 - 45 kg OS-03, 45 - 70 kg OS-04 and 70 - 100 kg OS-05. The pigs were allowed ad libitum access to feed and water. The diet of experimental group was supplemented with 0.75 mg.kg-1 CrNic in the form of chromium-inactivated yeast Saccharomyces cerevisiae. The fattening period in pigs lasted from 30 to 100 kg. The chromium supplementation led to a significantly higher content of chromium in longissimus thoracis muscle (LT of experimental pigs. In addition, the results showed a statistically significant difference (p ≤0.05 in retention of chromium in the LT, monounsaturated and omega-3 polyunsaturated fatty acids content in experimental group compared with control. Moreover, there was highly significant (p £0.05 difference in essential fatty acids, as well as in oxidative stability in 7 days, among the groups. The highly significant differences were also observed among sexes, namely in total water, protein and intramuscular fat contents, colour CIE b* in both times, and oxidative stability. However, physical-technological parameters (pH, drip loss, shear force and meat colour were not affected when pigs were fed the supplement. On the whole, the positive effect of chromium nicotinate in most of investigated parameters may be beneficial not only for pork industry but also for consumers. Normal 0 21 false false false

  11. Assumed non-persistent environmental chemicals in human adipose tissue; matrix stability and correlation with levels measured in urine and serum

    DEFF Research Database (Denmark)

    Artacho-Cordón, F; Arrebola, J P; Nielsen, O

    2017-01-01

    The aim of this study was to (1) optimize a method for the measurement of parabens and phenols in adipose tissue, (2) evaluate the stability of chemical residues in adipose tissue samples, and (3) study correlations of these compounds in urine, serum, and adipose tissue. Samples were obtained fro...

  12. Influence of encapsulated functional lipids on crystal structure and chemical stability in solid lipid nanoparticles: Towards bioactive-based design of delivery systems.

    Science.gov (United States)

    Salminen, Hanna; Gömmel, Christina; Leuenberger, Bruno H; Weiss, Jochen

    2016-01-01

    We investigated the influence of physicochemical properties of encapsulated functional lipids--vitamin A, β-carotene and ω-3 fish oil--on the structural arrangement of solid lipid nanoparticles (SLN). The relationship between the crystal structure and chemical stability of the incorporated bioactive lipids was evaluated with different emulsifier compositions of a saponin-rich, food-grade Quillaja extract alone or combined with high-melting or low-melting lecithins. The major factors influencing the structural arrangement and chemical stability of functional lipids in solid lipid dispersions were their solubility in the aqueous phase and their crystallization temperature in relation to that of the carrier lipid. The results showed that the stabilization of the α-subcell crystals in the lattice of the carrier lipid is a key parameter for forming stable solid lipid dispersions. This study contributes to a better understanding of SLN as a function of the bioactive lipid. Copyright © 2015 Elsevier Ltd. All rights reserved.

  13. Combining in situ chemical oxidation, stabilization, and anaerobic bioremediation in a single application to reduce contaminant mass and leachability in soil.

    Science.gov (United States)

    Cassidy, Daniel P; Srivastava, Vipul J; Dombrowski, Frank J; Lingle, James W

    2015-10-30

    Laboratory batch reactors were maintained for 32 weeks to test the potential for an in situ remedy that combines chemical oxidation, stabilization, and anaerobic bioremediation in a single application to treat soil from a manufactured gas plant, contaminated with polycyclic aromatic hydrocarbons (PAH) and benzene, toluene, ethylbenzene, and xylenes (BTEX). Portland cement and slaked lime were used to activate the persulfate and to stabilize/encapsulate the contaminants that were not chemically oxidized. Native sulfate-reducing bacteria degraded residual contaminants using the sulfate left after persulfate activation. The ability of the combined remedy to reduce contaminant mass and leachability was compared with NaOH-activated persulfate, stabilization, and sulfate-reducing bioremediation as stand-alone technologies. The stabilization amendments increased pH and temperature sufficiently to activate the persulfate within 1 week. Activation with both stabilization amendments and NaOH removed between 55% and 70% of PAH and BTEX. However, combined persulfate and stabilization significantly reduced the leachability of residual BTEX and PAH compared with NaOH activation. Sulfide, 2-naphthoic acid, and the abundance of subunit A of the dissimilatory sulfite reductase gene (dsrA) were used to monitor native sulfate-reducing bacteria, which were negatively impacted by activated persulfate, but recovered completely within weeks. Copyright © 2015 Elsevier B.V. All rights reserved.

  14. Chemical stability of seven years aged cement-PET composite waste form containing radioactive borate waste simulates

    Energy Technology Data Exchange (ETDEWEB)

    Saleh, H.M., E-mail: hosamsaleh70@yahoo.com [Radioisotope Department, Atomic Energy Authority, Dokki (Egypt); Tawfik, M.E. [Department of Polymers and Pigments, National Research Center, Dokki (Egypt); Bayoumi, T.A. [Radioisotope Department, Atomic Energy Authority, Dokki (Egypt)

    2011-04-15

    Different samples of radioactive borate waste simulate [originating from pressurized water reactors (PWR)] have been prepared and solidified after mixing with cement-water extended polyester composite (CPC). The polymer-cement composite samples were prepared from recycled poly (ethylene terephthalate) (PET) waste and cement paste (water/cement ratio of 40%). The prepared samples were left to set at room temperature (25 deg. C {+-} 5) under humid conditions. After 28 days curing time the obtained specimens were kept in their molds to age for 7 years under ambient conditions. Cement-polymer composite waste form specimens (CPCW) have been subjected to leach tests for both {sup 137}Cs and {sup 60}Co radionuclides according to the method proposed by the International Atomic Energy Agency (IAEA). Leaching tests were justified under various factors that may exist within the disposal site (e.g. type of leachant, surrounding temperature, leachant behavior, the leachant volume to CPCW surface area...). The obtained data after 260 days of leaching revealed that after 7 years of aging the candidate cement-polymer composite (CPC) containing radioactive borate waste samples are characterized by adequate chemical stability required for the long-term disposal process.

  15. Boosting Chemical Stability, Catalytic Activity, and Enantioselectivity of Metal-Organic Frameworks for Batch and Flow Reactions.

    Science.gov (United States)

    Chen, Xu; Jiang, Hong; Hou, Bang; Gong, Wei; Liu, Yan; Cui, Yong

    2017-09-27

    A key challenge in heterogeneous catalysis is the design and synthesis of heterogeneous catalysts featuring high catalytic activity, selectivity, and recyclability. Here we demonstrate that high-performance heterogeneous asymmetric catalysts can be engineered from a metal-organic framework (MOF) platform by using a ligand design strategy. Three porous chiral MOFs with the framework formula [Mn 2 L(H 2 O) 2 ] are prepared from enantiopure phosphono-carboxylate ligands of 1,1'-biphenol that are functionalized with 3,5-bis(trifluoromethyl)-, bismethyl-, and bisfluoro-phenyl substituents at the 3,3'-position. For the first time, we show that not only chemical stability but also catalytic activity and stereoselectivity of the MOFs can be tuned by modifying the ligand structures. Particularly, the MOF incorporated with -CF 3 groups on the pore walls exhibits enhanced tolerance to water, weak acid, and base compared with the MOFs with -F and -Me groups. Under both batch and flow reaction systems, the CF 3 -containing MOF demonstrated excellent reactivity, selectivity, and recyclability, affording high yields and enantioselectivities for alkylations of indoles and pyrrole with a range of ketoesters or nitroalkenes. In contrast, the corresponding homogeneous catalysts gave low enantioselectivity in catalyzing the tested reactions.

  16. High-temperature stability of chemically vapor-deposited tungsten-silicon couples rapid thermal annealed in ammonia and argon

    International Nuclear Information System (INIS)

    Broadbent, E.K.; Morgan, A.E.; Flanner, J.M.; Coulman, B.; Sadana, D.K.; Burrow, B.J.; Ellwanger, R.C.

    1988-01-01

    A rapid thermal anneal (RTA) in an NH 3 ambient has been found to increase the thermal stability of W films chemically vapor deposited (CVD) on Si. W films deposited onto single-crystal Si by low-pressure CVD were rapid thermal annealed at temperatures between 500 and 1100 0 C in NH 3 and Ar ambients. The reactions were studied using Rutherford backscattering spectrometry, x-ray diffraction, Auger electron spectroscopy, transmission electron microscopy, and four-point resistivity probe. High-temperature (≥1000 0 C) RTA in Ar completely converted W into the low resistivity (31 μΩ cm) tetragonal WSi 2 phase. In contrast, after a prior 900 0 C RTA in NH 3 , N inclusion within the W film and at the W/Si interface almost completely suppressed the W-Si reaction. Detailed examination, however, revealed some patches of WSi 2 formed at the interface accompanied by long tunnels extending into the substrate, and some crystalline precipitates in the substrate close to the interface. The associated interfacial contact resistance was only slightly altered by the 900 0 C NH 3 anneal. The NH 3 -treated W film acted as a diffusion barrier in an Al/W/Si contact metallurgy up to at least 550 0 C, at which point some increase in contact resistance was measured

  17. Greater-confinement disposal

    International Nuclear Information System (INIS)

    Trevorrow, L.E.; Schubert, J.P.

    1989-01-01

    Greater-confinement disposal (GCD) is a general term for low-level waste (LLW) disposal technologies that employ natural and/or engineered barriers and provide a degree of confinement greater than that of shallow-land burial (SLB) but possibly less than that of a geologic repository. Thus GCD is associated with lower risk/hazard ratios than SLB. Although any number of disposal technologies might satisfy the definition of GCD, eight have been selected for consideration in this discussion. These technologies include: (1) earth-covered tumuli, (2) concrete structures, both above and below grade, (3) deep trenches, (4) augered shafts, (5) rock cavities, (6) abandoned mines, (7) high-integrity containers, and (8) hydrofracture. Each of these technologies employ several operations that are mature,however, some are at more advanced stages of development and demonstration than others. Each is defined and further described by information on design, advantages and disadvantages, special equipment requirements, and characteristic operations such as construction, waste emplacement, and closure

  18. Greater oil investment opportunities

    International Nuclear Information System (INIS)

    Arenas, Ismael Enrique

    1997-01-01

    Geologically speaking, Colombia is a very attractive country for the world oil community. According to this philosophy new and important steps are being taken to reinforce the oil sector: Expansion of the exploratory frontier by including a larger number of sedimentary areas, and the adoption of innovative contracting instruments. Colombia has to offer, Greater economic incentives for the exploration of new areas to expand the exploratory frontier, stimulation of exploration in areas with prospectivity for small fields. Companies may offer Ecopetrol a participation in production over and above royalties, without it's participating in the investments and costs of these fields, more favorable conditions for natural gas seeking projects, in comparison with those governing the terms for oil

  19. Chemical Characterization and Oxidative Stability of Medium- and Long-Chain Fatty Acid Profiles in Tree-Borne Seed Oils

    Directory of Open Access Journals (Sweden)

    Da-Som Kim

    2018-01-01

    Full Text Available This study was undertaken to evaluate chemical characteristics and oxidative stability of tree-borne seed oils. A total of 15 different fatty acids were identified in six tree-borne seed oils, which included seven types of saturated fatty acids, four types of monounsaturated fatty acids, and four types of polyunsaturated fatty acids. Japanese camphor tree (JCT had a high content of medium-chain fatty acids (97.94 ± 0.04%, in which fatty acid composition was distinct from those of the other five plant seed oils. Overall, contents of tocopherols, a type of fat-soluble vitamin, ranged between 3.82 ± 0.04 mg/100 g and 101.98 ± 1.34 mg/100 g, respectively. Phytosterol contents ranged from 117.77 ± 1.32 mg/100 g to 479.45 ± 4.27 mg/100 g, respectively. Of all tree-borne seed oils, β-sitosterol was the phytosterol at the highest concentration. Contents of unsaponifiables were between 0.13 ± 0.08 and 2.01 ± 0.02, and values of acid, peroxide, and p-anisidine were between 0.79 ± 0.01 and 38.94 ± 0.24 mg KOH/g, 3.53 ± 0.21 and 127.67 ± 1.79 meq/kg, and 2.07 ± 0.51 and 9.67 ± 0.25, respectively. Oxidative stability of tree-borne seed oils was assessed through measurement of oxidation-induction periods. These results should serve as a foundation to identify the potential of tree-borne seed oils in industrial application as well as in providing fundamental data.

  20. Triacylglycerol composition, physico-chemical characteristics and oxidative stability of interesterified canola oil and fully hydrogenated cottonseed oil blends.

    Science.gov (United States)

    Imran, Muhammad; Nadeem, Muhammad

    2015-10-29

    Partial hydrogenation process is used worldwide to produce shortening, baking, and pastry margarines for food applications. However, demand for such products is decreased during last decade due to their possible links to consumer health and disease. This has raised the need to replace hydrogenation with alternative acceptable interesterification process which has advantage in context of modifying the physico-chemical properties of edible fat-based products. Therefore, the main mandate of research was the development of functional fat through chemical interesterification of canola oil (CaO) and fully hydrogenated cottonseed oil (FHCSO) mixtures. Blends were prepared in the proportions of 75:25 (T1), 50:50 (T2) and 25:75 (T3) of CaO:FHCSO (w/w). Interesterification was performed using sodium methoxide (0.2 %) as catalyst at 120 °C, under reduced pressure and constant agitation for 60 minutes. The non-interesterified and interesterified CaO:FHCSO blends were evaluated for triacylglycerol (TAG) composition, physico-chemical characteristics, oxidative stability and consumer acceptability at 0, 30 and 60 days of storage interval. The oleic acid (58.3 ± 0.6 %) was predominantly present in CaO while the contents of stearic acid (72 ± 0.8 %) were significantly higher in FHCSO. Maximum trisaturated (S3) contents (63.9 ± 0.5 %) were found in T3 while monounsaturated (S2U), diunsaturated (U2S) and triunsaturated (U3) contents were quite low in T2 and T3 before interesterification. A marked reduction in S3 and U3 contents with concomitant increase in S2U and U2S contents was observed for all CaO:FHCSO blends on interesterification. During storage, the changes in S3, S2U and U2S contents were not found significant (p ≥ 0.05). However, maximum decrease 13 %, 7.5 and 5.6 % in U3 contents for T1, T2 and T3 was noted after 60-days of interesterification, respectively. The Lovibond color R, melting point, refractive index, specific gravity, peroxide and free

  1. Combining in situ chemical oxidation, stabilization, and anaerobic bioremediation in a single application to reduce contaminant mass and leachability in soil

    Energy Technology Data Exchange (ETDEWEB)

    Cassidy, Daniel P., E-mail: daniel.cassidy@wmich.edu [Department of Geosciences, Western Michigan University, Kalamazoo, MI 49008 (United States); Srivastava, Vipul J., E-mail: vipul.srivastava@ch2m.com [CH2M HILL, 125S Wacker, Ste 3000, Chicago, IL 60606 (United States); Dombrowski, Frank J., E-mail: frank.dombrowski@we-energies.com [We Energies, 333W Everett St., A231, Milwaukee, WI 53203 (United States); Lingle, James W., E-mail: jlingle@epri.com [Electric Power Research Institute (EPRI), 4927W Willow Road, Brown Deer, WI 53223 (United States)

    2015-10-30

    Highlights: • Portland cement and lime activated persulfate by increasing pH and temperature. • Chemical oxidation achieved BTEX and PAH removal ranging from 55% to 75%. • Activating persulfate with ISS amendments reduced leachability more than NaOH. • Native sulfate-reducing bacteria degraded PAHs within weeks after ISCO finished. • ISCO, ISS, and anaerobic bioremediation were combined in a single application. - Abstract: Laboratory batch reactors were maintained for 32 weeks to test the potential for an in situ remedy that combines chemical oxidation, stabilization, and anaerobic bioremediation in a single application to treat soil from a manufactured gas plant, contaminated with polycyclic aromatic hydrocarbons (PAH) and benzene, toluene, ethylbenzene, and xylenes (BTEX). Portland cement and slaked lime were used to activate the persulfate and to stabilize/encapsulate the contaminants that were not chemically oxidized. Native sulfate-reducing bacteria degraded residual contaminants using the sulfate left after persulfate activation. The ability of the combined remedy to reduce contaminant mass and leachability was compared with NaOH-activated persulfate, stabilization, and sulfate-reducing bioremediation as stand-alone technologies. The stabilization amendments increased pH and temperature sufficiently to activate the persulfate within 1 week. Activation with both stabilization amendments and NaOH removed between 55% and 70% of PAH and BTEX. However, combined persulfate and stabilization significantly reduced the leachability of residual BTEX and PAH compared with NaOH activation. Sulfide, 2-naphthoic acid, and the abundance of subunit A of the dissimilatory sulfite reductase gene (dsrA) were used to monitor native sulfate-reducing bacteria, which were negatively impacted by activated persulfate, but recovered completely within weeks.

  2. Combining in situ chemical oxidation, stabilization, and anaerobic bioremediation in a single application to reduce contaminant mass and leachability in soil

    International Nuclear Information System (INIS)

    Cassidy, Daniel P.; Srivastava, Vipul J.; Dombrowski, Frank J.; Lingle, James W.

    2015-01-01

    Highlights: • Portland cement and lime activated persulfate by increasing pH and temperature. • Chemical oxidation achieved BTEX and PAH removal ranging from 55% to 75%. • Activating persulfate with ISS amendments reduced leachability more than NaOH. • Native sulfate-reducing bacteria degraded PAHs within weeks after ISCO finished. • ISCO, ISS, and anaerobic bioremediation were combined in a single application. - Abstract: Laboratory batch reactors were maintained for 32 weeks to test the potential for an in situ remedy that combines chemical oxidation, stabilization, and anaerobic bioremediation in a single application to treat soil from a manufactured gas plant, contaminated with polycyclic aromatic hydrocarbons (PAH) and benzene, toluene, ethylbenzene, and xylenes (BTEX). Portland cement and slaked lime were used to activate the persulfate and to stabilize/encapsulate the contaminants that were not chemically oxidized. Native sulfate-reducing bacteria degraded residual contaminants using the sulfate left after persulfate activation. The ability of the combined remedy to reduce contaminant mass and leachability was compared with NaOH-activated persulfate, stabilization, and sulfate-reducing bioremediation as stand-alone technologies. The stabilization amendments increased pH and temperature sufficiently to activate the persulfate within 1 week. Activation with both stabilization amendments and NaOH removed between 55% and 70% of PAH and BTEX. However, combined persulfate and stabilization significantly reduced the leachability of residual BTEX and PAH compared with NaOH activation. Sulfide, 2-naphthoic acid, and the abundance of subunit A of the dissimilatory sulfite reductase gene (dsrA) were used to monitor native sulfate-reducing bacteria, which were negatively impacted by activated persulfate, but recovered completely within weeks

  3. Scandium complexes: physico-chemical study and evaluation of stability in vitro and in vivo for nuclear medicine application

    International Nuclear Information System (INIS)

    Kerdjoudj, Rabha

    2014-01-01

    Among the different isotopes of Scandium that can be used in nuclear medicine may be mentioned the 47 Sc and 44 Sc. The first decays by emitting an electron associated with a 159 keV gamma can thus be used either for radiotherapy or TEMP imaging. The 44 Sc (3.97 h) decays in 94.27% in case by emitting a positron, with a γ photon energy equal to 1.157 MeV. This isotope is then an ideal candidate for applications in PET imaging. Currently, the Cyclotron of high energy and high intensity ARRONAX produce 44 Sc and co-produces the isomeric state the 44m Sc (2.44 d). The 44m Sc has properties (E(γ) = 270 keV, 98.8%), which allows to consider its use as a potential in vivo generator. Previous work had demonstrated that the DOTA ligand is most suitable and stable for Sc. This thesis aims; make in evidence the feasibility of the in vivo 44m / 44 Sc generator. Initially a procedure was optimized and validated for the production of 44m / 44 Sc with a high specific activity and chemical purity. Radiolabeling of DOTA conjugated peptides was then developed and optimized. Theoretical and experimental studies have been performed in order to demonstrate the feasibility of 44m / 44 Sc as a potential in vivo generator. Finally, in vitro stability studies on radiolabeled 44m / 44 Sc complexes were performed, followed by biodistribution studies and PET imaging. (author)

  4. Enhanced permanganate in situ chemical oxidation through MnO2 particle stabilization: evaluation in 1-D transport systems.

    Science.gov (United States)

    Crimi, Michelle; Quickel, Mark; Ko, Saebom

    2009-02-27

    In situ chemical oxidation using permanganate is an increasingly employed approach to organic contaminant remediation at hazardous waste sites. Manganese dioxide (MnO2) particles form as a by-product of the reaction of permanganate with contaminants and naturally-reduced subsurface materials. These particles are of interest because they have the potential to deposit in the subsurface and impact the flow regime in/around permanganate injection, including the well screen, filter pack, and the surrounding subsurface formation. Control of these particles can allow for improved oxidant injection and transport, and contact between the oxidant and contaminants of concern. Sodium hexametaphosphate (HMP) has previously been identified as a promising aid to stabilize MnO2 in solution when included in the oxidizing solution, increasing the potential to inhibit particle deposition and impact subsurface flow. The goal of the experimental studies described herein was to investigate the ability of HMP to prevent particle deposition in transport studies using four different types of porous media. Permanganate was delivered to a contaminant source zone (trichloroethylene) located within four different media types with variations in sand, clay, organic carbon, and iron oxides (as goethite) content. Deposition of MnO2 within the columns was quantified with distance from the source zone. Experiments were repeated in replicate columns with the inclusion of HMP directly with the oxidant delivery solution, and MnO2 deposition was again quantified. While total MnO2 deposition within the 60 cm columns did not change significantly with the addition of HMP, deposition within the contaminant source zone decreased by 25-85%, depending on the specific media type. The greatest differences in deposition were observed in the goethite-containing and clay-containing columns. Columns containing these two media types experienced completely plugged flow in the oxidant-only delivery systems; however

  5. Incorporation of Fe2O3, FeO and Al2O3 in silicate glasses and its effect on their structure and chemical stability

    Energy Technology Data Exchange (ETDEWEB)

    Van Iseghem, P; De Grave, E; Peters, L; De Batist, R

    1983-09-01

    Large amounts of the glass intermediates Al2O3, Fe2O3 and FeO are present in the amorphous silicate slags developed at the S.C.K./C.E.N. for the conditioning of Pu contaminated radioactive waste. Strong ambiguity exists in literature about both the structural incorporation and the effect on the chemical stability of Fe2O3 and FeO. The chemical stability and its relationship to the glass structure therefore was investigated for a number of silicate base glasses, taking into consideration the following parameters (the amount of glass modifiers was kept constant at 16 mole %, equimolarly spread over Li2O, K2O, MgO and CaO): 1) Fe2Ox concentrations (x = 2 or 3) varying between 2.5 and 30 mole % (compensated by changes in SiO2 concentration); 2)Equimolar replacement of Fe2Ox by Al2O3 and Fe2Ox in all glasses listed in 1. The structural incorporation of Fe2Ox was investigated by 57 Fe Mossbauer Spectroscopy, the chemical stability by the Soxhlet corrosion test. The sample weight was measured after 14 days of corrosion, after drying and removal of the weakly bounded surface layer.

  6. Influence of chemical and physical characteristics of cement kiln dusts (CKDs) on their hydration behavior and potential suitability for soil stabilization

    International Nuclear Information System (INIS)

    Peethamparan, Sulapha; Olek, Jan; Lovell, Janet

    2008-01-01

    The interaction of CKDs with a given soil depends on the chemical and physical characteristics of the CKDs. Hence, the characterization of CKDs and their hydration products may lead to better understanding of their suitability as soil stabilizers. In the present article, four different CKD powders are characterized and their hydration products are evaluated. A detailed chemical (X-ray diffraction), thermogravimetric and morphological (scanning electron microscope) analyses of both the CKD powders and the hydrated CKD pastes are presented. In general, high free-lime content (∼ 14-29%) CKDs, when reacted with water produced significant amounts of calcium hydroxide, ettringite and syngenite. These CKDs also developed higher unconfined compressive strength and higher temperature of hydration compared to CKDs with lower amounts of free-lime. An attempt was made to qualitatively correlate the performance of CKD pastes with the chemical and physical characteristics of the original CKD powders and to determine their potential suitability as soil stabilizers. To that effect a limited unconfined compressive strength testing of CKD-treated kaolinite clays was performed. The results of this study suggest that both the compressive strength and the temperature of hydration of the CKD paste can give early indications of the suitability of particular CKD for soil stabilization

  7. A high-response transparent heater based on a CuS nanosheet film with superior mechanical flexibility and chemical stability.

    Science.gov (United States)

    Xie, Shuyao; Li, Teng; Xu, Zijie; Wang, Yanan; Liu, Xiangyang; Guo, Wenxi

    2018-04-05

    Transparent heaters are widely used in technologies such as window defrosting/defogging, displays, gas sensing, and medical equipment. Apart from mechanical robustness and electrical and optical reliabilities, outstanding chemical stability is also critical to the application of transparent heaters. In this regard, we first present a highly flexible and large-area CuS transparent heater fabricated by a colloidal crackle pattern method with an optimized sheet resistance (Rs) as low as 21.5 Ω sq-1 at a ∼80% transmittance. The CuS transparent heater exhibits remarkable mechanical robustness during bending tests as well as high chemical stability against acid and alkali environments. In the application as a transparent heater, the CuS heater demonstrates a high thermal resistance of 197 °C W-1 cm2 with a fast switching time (solar panels. These CuS network TCEs with high flexibility, transparency, conductivity, and chemical stability could be widely used in wearable electronic products.

  8. Development of the chemical stabilization and solidification process for the treatment of radioactive raffinate sludges at the DOE Weldon Spring Site Remedial Action Project

    International Nuclear Information System (INIS)

    Cole, P.M.; Kakaria, V.; Enger, J.

    1996-01-01

    Chemical Solidification and Stabilization (CSS) is the mixing of chemical reagents with waste to solidify and chemically stabilize the contaminated material. The resulting product is resistant to leaching of certain contaminants. CSS treatment using Class C fly ash and Portland cement was chosen as the most feasible method for treatment of the chemically and radioactively contaminated sludge (raffinate) contained in raffinate pits on the Weldon Spring Site Remedial Action Project (WSSRAP) located outside of St. Louis, Missouri. Due to the uniqueness of the material, substantial bench-scale testing was performed on the raffinate to better understand its properties. Similarly, due to mixed results in the application of CSS treatment to radioactive materials, a pilot-scale testing facility was built to verify bench testing results and to establish and quantify design parameters for the full-scale CSS production facility. This paper discusses the development of the pilot-scale testing facility, the testing plan, and the results of the testing activities. Particular attention has been given to the applicability of the CSS treatment method and to the value of pilot-scale testing

  9. Solid-phase extraction combined with high-performance liquid chromatography-atmospheric pressure chemical ionization-mass spectrometry analysis of pesticides in water: method performance and application in a reconnaissance survey of residues in drinking water in Greater Cairo, Egypt.

    Science.gov (United States)

    Potter, Thomas L; Mohamed, Mahmoud A; Ali, Hannah

    2007-01-24

    Monitoring of water resources for pesticide residues is often needed to ensure that pesticide use does not adversely impact the quality of public water supplies or the environment. In many rural areas and throughout much of the developing world, monitoring is often constrained by lack of testing facilities; thus, collection of samples and shipment to centralized laboratories for analysis is required. The portability, ease of use, and potential to enhance analyte stability make solid-phase extraction (SPE) an attractive technique for handling water samples prior to their shipment. We describe performance of an SPE method targeting a structurally diverse mixture of 25 current-use pesticides and two common degradates in samples of raw and filtered drinking water collected in Greater Cairo, Egypt. SPE was completed in a field laboratory in Egypt, and cartridges were shipped to the United States for elution and high-performance liquid chromatography-atmospheric pressure chemical ionization-mass spectrometry analysis. Quantitative and reproducible recovery of 23 of 27 compounds (average = 96%; percent relative standard deviation = 21%) from matrix spikes (1 microg L-1 per component) prepared in the field and from deionized water fortified similarly in the analytical laboratory was obtained. Concurrent analysis of unspiked samples identified four parent compounds and one degradate in drinking water samples. No significant differences were observed between raw and filtered samples. Residue levels in all cases were below drinking water and "harm to aquatic-life" thresholds, indicating that human and ecological risks of pesticide contamination were relatively small; however, the study was limited in scale and scope. Further monitoring is needed to define spatial and temporal variation in residue concentrations. The study has demonstrated the feasibility of performing studies of this type using SPE to extract and preserve samples in the field. The approach should be broadly

  10. Concurrent Increases and Decreases in Local Stability and Conformational Heterogeneity in Cu, Zn Superoxide Dismutase Variants Revealed by Temperature-Dependence of Amide Chemical Shifts.

    Science.gov (United States)

    Doyle, Colleen M; Rumfeldt, Jessica A; Broom, Helen R; Sekhar, Ashok; Kay, Lewis E; Meiering, Elizabeth M

    2016-03-08

    The chemical shifts of backbone amide protons in proteins are sensitive reporters of local structural stability and conformational heterogeneity, which can be determined from their readily measured linear and nonlinear temperature-dependences, respectively. Here we report analyses of amide proton temperature-dependences for native dimeric Cu, Zn superoxide dismutase (holo pWT SOD1) and structurally diverse mutant SOD1s associated with amyotrophic lateral sclerosis (ALS). Holo pWT SOD1 loses structure with temperature first at its periphery and, while having extremely high global stability, nevertheless exhibits extensive conformational heterogeneity, with ∼1 in 5 residues showing evidence for population of low energy alternative states. The holo G93A and E100G ALS mutants have moderately decreased global stability, whereas V148I is slightly stabilized. Comparison of the holo mutants as well as the marginally stable immature monomeric unmetalated and disulfide-reduced (apo(2SH)) pWT with holo pWT shows that changes in the local structural stability of individual amides vary greatly, with average changes corresponding to differences in global protein stability measured by differential scanning calorimetry. Mutants also exhibit altered conformational heterogeneity compared to pWT. Strikingly, substantial increases as well as decreases in local stability and conformational heterogeneity occur, in particular upon maturation and for G93A. Thus, the temperature-dependence of amide shifts for SOD1 variants is a rich source of information on the location and extent of perturbation of structure upon covalent changes and ligand binding. The implications for potential mechanisms of toxic misfolding of SOD1 in disease and for general aspects of protein energetics, including entropy-enthalpy compensation, are discussed.

  11. Evaluating Chemical Reactivity And Mechanical Stability Of Nano Palladized Iron Embedded In Activated Carbon On Dechlorination Of Polychlorinated Biphenyls

    Science.gov (United States)

    Remediation of contaminated sites with hydrophobic organic compounds such as polychlorinated biphenyls (PCBs) remains a scientific and technical challenge. The high stability, low aqueous solubility, and high organic affinity of PCBs make them difficult to treat. Many physical,...

  12. Chemical and radiation stability of SuperLig reg-sign 644, resorcinol-formaldehyde, and CS-100 cesium ion exchange materials

    International Nuclear Information System (INIS)

    Brown, G.N.; Adami, S.R.; Bray, L.A.

    1995-09-01

    At the request of the Initial Pretreatment Module Project within Westinghouse Hanford Company, Pacific Northwest Laboratory (PNL) conducted this study for the Efficient Separations and Processing Crosscutting Program (ESP) under the task ''Develop and Test Sorbents.'' The purpose of the study was to assess and compare the chemical and radiolytic stability of several cesium-selective ion exchange materials in simulated alkaline Hanford tank waste matrices. Pretreatment of nuclear process wastes to remove of cesium and other radionuclides by ion exchange was proposed previously as one method of minimizing the amount of high-level radioactive waste at Hanford. In this study, PNL evaluated three cesium-selective materials SuperLig reg-sign 644, resorcinol-formaldehyde (R-F), and CS-100 for chemical and radiation stability in 1 M NaOH and a simulated neutralized current acid waste (NCAW). The objective of the study is to investigate the stability of the newly produced SuperLig reg-sign 644 under a variety of conditions in an attempt to simulate and predict the degradation process. The following specific conclusions and recommendations resulted from the study

  13. Chemical and radiation stability of SuperLig{reg_sign}644, resorcinol-formaldehyde, and CS-100 cesium ion exchange materials

    Energy Technology Data Exchange (ETDEWEB)

    Brown, G.N.; Adami, S.R.; Bray, L.A. [and others

    1995-09-01

    At the request of the Initial Pretreatment Module Project within Westinghouse Hanford Company, Pacific Northwest Laboratory (PNL) conducted this study for the Efficient Separations and Processing Crosscutting Program (ESP) under the task ``Develop and Test Sorbents.`` The purpose of the study was to assess and compare the chemical and radiolytic stability of several cesium-selective ion exchange materials in simulated alkaline Hanford tank waste matrices. Pretreatment of nuclear process wastes to remove of cesium and other radionuclides by ion exchange was proposed previously as one method of minimizing the amount of high-level radioactive waste at Hanford. In this study, PNL evaluated three cesium-selective materials SuperLig{reg_sign}644, resorcinol-formaldehyde (R-F), and CS-100 for chemical and radiation stability in 1 M NaOH and a simulated neutralized current acid waste (NCAW). The objective of the study is to investigate the stability of the newly produced SuperLig{reg_sign}644 under a variety of conditions in an attempt to simulate and predict the degradation process. The following specific conclusions and recommendations resulted from the study.

  14. Waste management in Greater Vancouver

    Energy Technology Data Exchange (ETDEWEB)

    Carrusca, K. [Greater Vancouver Regional District, Burnaby, BC (Canada); Richter, R. [Montenay Inc., Vancouver, BC (Canada)]|[Veolia Environmental Services, Vancouver, BC (Canada)

    2006-07-01

    An outline of the Greater Vancouver Regional District (GVRD) waste-to-energy program was presented. The GVRD has an annual budget for solid waste management of $90 million. Energy recovery revenues from solid waste currently exceed $10 million. Over 1,660,00 tonnes of GVRD waste is recycled, and another 280,000 tonnes is converted from waste to energy. The GVRD waste-to-energy facility combines state-of-the-art combustion and air pollution control, and has processed over 5 million tonnes of municipal solid waste since it opened in 1988. Its central location minimizes haul distance, and it was originally sited to utilize steam through sales to a recycle paper mill. The facility has won several awards, including the Solid Waste Association of North America award for best facility in 1990. The facility focuses on continual improvement, and has installed a carbon injection system; an ammonia injection system; a flyash stabilization system; and heat capacity upgrades in addition to conducting continuous waste composition studies. Continuous air emissions monitoring is also conducted at the plant, which produces a very small percentage of the total air emissions in metropolitan Vancouver. The GVRD is now seeking options for the management of a further 500,000 tonnes per year of solid waste, and has received 23 submissions from a range of waste energy technologies which are now being evaluated. It was concluded that waste-to-energy plants can be located in densely populated metropolitan areas and provide a local disposal solution as well as a source of renewable energy. Other GVRD waste reduction policies were also reviewed. refs., tabs., figs.

  15. Evaluation of chemical stability of polymers of XIENCE everolimus-eluting coronary stents in vivo by pyrolysis-gas chromatography/mass spectrometry.

    Science.gov (United States)

    Kamberi, Marika; Pinson, David; Pacetti, Stephen; Perkins, Laura E L; Hossainy, Syed; Mori, Hiroyoshi; Rapoza, Richard J; Kolodgie, Frank; Virmani, Renu

    2017-09-07

    The polymers poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) and poly(n-butyl methacrylate) (PBMA) are employed in manufacturing the XIENCE family of coronary stents. PBMA serves as a primer and adheres to both the stent and the drug coating. PVDF-HFP is employed in the drug matrix layer to hold the drug everolimus on the stent and control its release. Chemical stability of the polymers of XIENCE stents in the in-vivo environment was evaluated by pyrolysis-gas chromatography with mass spectrometry (Py-GC/MS) detection. For this evaluation, XIENCE stents explanted from porcine coronary arteries and from human coronary artery specimens at autopsy after 2-4 and 5-7 years of implantation, respectively, were compared to freshly manufactured XIENCE stents (controls). The comparison of pyrograms of explanted stent samples and controls showed identical fragmentation fingerprints of polymers, indicating that PVDF-HFP and PBMA maintained their chemical integrity after multiple years of XIENCE coronary stent implantation. The findings of the present study demonstrate the chemical stability of PVDF-HFP and PBMA polymers of the XIENCE family of coronary stents in the in-vivo environment, and constitute a further proof of the suitability of PVDF-HFP as a drug carrier for the drug eluting stent applications. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2017. © 2017 Wiley Periodicals, Inc.

  16. Electronic structure, chemical bonding, phase stability, and ground-state properties of YNi2-x(Co/Cu)xB2C

    International Nuclear Information System (INIS)

    Ravindran, P.; Johansson, B.; Eriksson, O.

    1998-01-01

    In order to understand the role of Ni site substitution on the electronic structure and chemical bonding in YNi 2 B 2 C, we have made systematic electronic-structure studies on YNi 2 B 2 C as a function of Co and Cu substitution using the supercell approach within the local density approximation. The equilibrium volume, bulk modulus (B 0 ) and its pressure derivative (B 0 ' ), Grueneisen constant (γ G ), Debye temperature (Θ D ), cohesive energy (E c ), and heat of formation (ΔH) are calculated for YNi 2-x (Co/Cu) x B 2 C (x=0,0.5,1.0,1.5,2). From the total energy, electron-energy band structure, site decomposed density of states, and charge-density contour we have analyzed the structural stability and chemical bonding behavior of YNi 2 B 2 C as a function of Co/Cu substitution. We find that the simple rigid band model successfully explains the electronic structure and structural stability of Co/Cu substitution for Ni. In addition to studying the chemical bonding and electronic structure we present a somewhat speculative analysis of the general trends in the behavior of critical temperature for superconductivity as a function of alloying. copyright 1998 The American Physical Society

  17. Specificity of HPLC to assess the chemical stability based on partenine from Parthenium hysterophorus L. powdered dry foliage (escoba amarga)

    International Nuclear Information System (INIS)

    Saucedo Hernandez, Yanelis; Mohamad Safa, Bassam; Gonzalez Bedia, Mirtha Mayra

    2010-01-01

    It is required a specific analysis technique allowing the follow-up to stability study intrinsic of Parthenium hysterophorus L. (escoba amarga) powdered dry foliage to achieve in a pharmaceutical way a antiparasitic usefulness with the quality, safety and effectiveness demanded requirements. High performance liquid chromatography was applied to P. hysterophorus degraded samples under degradation conditions in an oxidative, basic and acid medium. The analysis technique specificity was assessed to detect the interest component without interferences of its degradation products and its possible usefulness in studies on solid stability in the plant powder

  18. Impacts of fire, fire-fighting chemicals and post-fire stabilization techniques on the soil-plant system

    OpenAIRE

    Fernández Fernández, María

    2017-01-01

    Forest fires, as well as fire-fighting chemicals, greatly affect the soil-plant system causing vegetation loss, alterations of soil properties and nutrient losses through volatilization, leaching and erosion. Soil recovery after fires depends on the regeneration of the vegetation cover, which protects the soil and prevents erosion. Fire-fighting chemicals contain compounds potentially toxic for plants and soil organisms, and thus their use might hamper the regeneration of burnt ecosystems. In...

  19. Chemical stability of conductive ceramic anodes in LiCl–Li{sub 2}O molten salt for electrolytic reduction in pyroprocessing

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Sung Wook; Kang, Hyun Woo; Jeon, Min Ku; Lee, Sang Kwon; Choi, Eun Young; Park, Woo Shin; Hong, Sun Seok; Oh, Seung Chul; Hur, Jin Mok [Nuclear Fuel Cycle Process Development Group, Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2016-08-15

    Conductive ceramics are being developed to replace current Pt anodes in the electrolytic reduction of spent oxide fuels in pyroprocessing. While several conductive ceramics have shown promising electrochemical properties in small-scale experiments, their long-term stabilities have not yet been investigated. In this study, the chemical stability of conductive La{sub 0.33}Sr{sub 0.67}MnO{sub 3} in LiCl–Li{sub 2}O molten salt at 650°C was investigated to examine its feasibility as an anode material. Dissolution of Sr at the anode surface led to structural collapse, thereby indicating that the lifetime of the La{sub 0.33}Sr{sub 0.67}MnO{sub 3} anode is limited. The dissolution rate of Sr is likely to be influenced by the local environment around Sr in the perovskite framework.

  20. Complexes of lutein with bovine and caprine caseins and their impact on lutein chemical stability in emulsion systems: Effect of arabinogalactan.

    Science.gov (United States)

    Mora-Gutierrez, A; Attaie, R; Núñez de González, M T; Jung, Y; Woldesenbet, S; Marquez, S A

    2018-01-01

    Lutein is an important xanthophyll carotenoid with many benefits to human health. Factors affecting the application of lutein as a functional ingredient in low-fat dairy-like beverages (pH 6.0-7.0) are not well understood. The interactions of bovine and caprine caseins with hydrophobic lutein were studied using UV/visible spectroscopy as well as fluorescence. Our studies confirmed that the aqueous solubility of lutein is improved after binding with bovine and caprine caseins. The rates of lutein solubilization by the binding to bovine and caprine caseins were as follows: caprine α S1 -II-casein 34%, caprine α S1 -I-casein 10%, and bovine casein 7% at 100 μM lutein. Fluorescence of the protein was quenched on binding supporting complex formation. The fluorescence experiments showed that the binding involves tryptophan residues and some nonspecific interactions. Scatchard plots of lutein binding to the caseins demonstrated competitive binding between the caseins and their sites of interaction with lutein. Competition experiments suggest that caprine α S1 -II casein will bind a larger number of lutein molecules with higher affinity than other caseins. The chemical stability of lutein was largely dependent on casein type and significant increases occurred in the chemical stability of lutein with the following pattern: caprine α S1 -II-casein > caprine α S1 -I-casein > bovine casein. Addition of arabinogalactan to lutein-enriched emulsions increases the chemical stability of lutein-casein complexes during storage under accelerated photo-oxidation conditions at 25°C. Therefore, caprine α S1 -II-casein alone and in combination with arabinogalactan can have important applications in the beverage industry as carrier of this xanthophyll carotenoid (lutein). Copyright © 2018 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

  1. Physico-Chemical Strategies to Enhance Stability and Drug Retention of Polymeric Micelles for Tumor-Targeted Drug Delivery

    NARCIS (Netherlands)

    Shi, Y.; Lammers, Twan Gerardus Gertudis Maria; Storm, Gerrit; Hennink, W.E.

    2017-01-01

    Polymeric micelles (PM) have been extensively used for tumor-targeted delivery of hydrophobic anti-cancer drugs. The lipophilic core of PM is naturally suitable for loading hydrophobic drugs and the hydrophilic shell endows them with colloidal stability and stealth properties. Decades of research on

  2. Encapsulating betalains from Opuntia ficus-indica fruits by ionic gelation: Pigment chemical stability during storage of beads.

    Science.gov (United States)

    Otálora, María Carolina; Carriazo, José Gregorio; Iturriaga, Laura; Osorio, Coralia; Nazareno, Mónica Azucena

    2016-07-01

    Betalain encapsulation was performed by ionic gelation as a stabilization strategy for these natural pigments. Betalains were extracted from purple cactus fruits and encapsulated in calcium-alginate and in combination of calcium alginate and bovine serum albumin. Beads were characterised by scanning electron microscopy and thermal analysis using differential scanning calorimetry and thermogravimetry. Moisture sorption isotherms were determined. Bead morphology was affected by matrix composition. Pigments storage stability was evaluated at different equilibrium relative humidity and temperatures. Pigment composition of beads was determined by HPLC-MS-MS and degradation products were also analysed after storage; betalamic acid being the major one. Both types of matrices protected the encapsulated pigments, being their storage stability better at low relative humidity than that of the non-encapsulated control material. Antiradical activities of beads were proportional to remaining betalain contents. At high relative humidity, there was no protection and low storage stability was observed in the samples. Copyright © 2016 Elsevier Ltd. All rights reserved.

  3. Delocalization does not always stabilize : a quantum chemical analysis of -substituent effects on 54 alkyl and vinyl cations

    NARCIS (Netherlands)

    Alem, van K.; Lodder, G.; Zuilhof, H.

    2002-01-01

    The effects of -substituents on alkyl and vinyl cations are studied using high-level ab initio calculations. The geometries, stabilities, and electronic properties of 27 alkyl cations and 27 vinyl cations with -substituents are computed at the B3LYP/6-311 G(d,p), MP2/6-311 G(d,p), and CBS-Q levels.

  4. Effect of chemical stabilizers on the thermostability and infectivity of a representative panel of freeze dried viruses.

    Directory of Open Access Journals (Sweden)

    Boris Pastorino

    Full Text Available As a partner of the European Virus Archive (EVA FP7 project, our laboratory maintains a large collection of freeze-dried viruses. The distribution of these viruses to academic researchers, public health organizations and industry is one major aim of the EVA consortium. It is known that lyophilization requires appropriate stabilizers to prevent inactivation of the virus. However, few studies have investigated the influence of different stabilizers and lyophilization protocols on the thermostability of different viruses. In order to identify optimal lyophilization conditions that will deliver maximum retention of viral infectivity titre, different stabilizer formulations containing trehalose, sorbitol, sucrose or foetal bovine serum were evaluated for their efficacy in stabilizing a representative panel of freeze dried viruses at different storage temperatures (-20°C, +4°C and +20°C for one week, the two latter mimicking suboptimal shipping conditions. The Tissue Culture Infectious Dose 50% (TCID50 assay was used to compare the titres of infectious virus. The results obtained using four relevant and model viruses (enveloped/non enveloped RNA/DNA viruses still serve to improve the freeze drying conditions needed for the development and the distribution of a large virus collection.

  5. Advances in simultaneous DSC-FTIR microspectroscopy for rapid solid-state chemical stability studies: some dipeptide drugs as examples.

    Science.gov (United States)

    Lin, Shan-Yang; Wang, Shun-Li

    2012-04-01

    The solid-state chemistry of drugs has seen growing importance in the pharmaceutical industry for the development of useful API (active pharmaceutical ingredients) of drugs and stable dosage forms. The stability of drugs in various solid dosage forms is an important issue because solid dosage forms are the most common pharmaceutical formulation in clinical use. In solid-state stability studies of drugs, an ideal accelerated method must not only be selected by different complicated methods, but must also detect the formation of degraded product. In this review article, an analytical technique combining differential scanning calorimetry and Fourier-transform infrared (DSC-FTIR) microspectroscopy simulates the accelerated stability test, and simultaneously detects the decomposed products in real time. The pharmaceutical dipeptides aspartame hemihydrate, lisinopril dihydrate, and enalapril maleate either with or without Eudragit E were used as testing examples. This one-step simultaneous DSC-FTIR technique for real-time detection of diketopiperazine (DKP) directly evidenced the dehydration process and DKP formation as an impurity common in pharmaceutical dipeptides. DKP formation in various dipeptides determined by different analytical methods had been collected and compiled. Although many analytical methods have been applied, the combined DSC-FTIR technique is an easy and fast analytical method which not only can simulate the accelerated drug stability testing but also at the same time enable to explore phase transformation as well as degradation due to thermal-related reactions. This technique offers quick and proper interpretations. Copyright © 2012 Elsevier B.V. All rights reserved.

  6. High pressure stability analysis and chemical bonding of Ti{sub 1-x}Zr{sub x}N alloy: A first principle study

    Energy Technology Data Exchange (ETDEWEB)

    Chauhan, Mamta; Gupta, Dinesh C., E-mail: sosfizix@gmail.com, E-mail: mamta-physics@yahoo.co.in [Condensed Matter Theory Group, School of Studies in Physics, Jiwaji University, Gwalior – 474 011 (India)

    2016-05-23

    First-principles pseudo-potential calculations have been performed to analyze the stability of Ti{sub 1-x}Zr{sub x}N alloy under high pressures. The first order phase transition from B1 to B2 phase has been observed in this alloy at high pressure. The variation of lattice parameter with the change in concentration of Zr atom in Ti{sub 1-x}Zr{sub x}N is also reported in both the phases. The calculations for density of states have been performed to understand the alloying effects on chemical bonding of Ti-Zr-N alloy.

  7. The influence of incorporating MgO into Ni-based cermets by plasma spraying on anode microstructural and chemical stability in dry methane

    Science.gov (United States)

    Lay, E.; Metcalfe, C.; Kesler, O.

    2012-11-01

    The Solution Precursor Plasma Spray (SPPS) process was successfully used to deposit cermet coatings that exhibit fine microstructures with high surface area. MgO addition in Ni-YSZ and Ni-SDC cermets results in (Ni,Mg)O solid solution formation, and nickel particles after reduction are finer than in coatings without magnesia. The influence of MgO on the chemical stability of cermets in anodic operating conditions is discussed. It was found that a sufficient amount of magnesia addition (Ni0.9(MgO)0.1) helps to reduce carbon deposition in dry methane.

  8. DNA damage, acetylcholinesterase activity and lysosomal stability in native and transplanted mussels (Mytilus edulis) in areas close to coastal chemical dumping sites in Denmark

    DEFF Research Database (Denmark)

    Rank, Jette; Lehtonen, Kari K.; Strand, Jakob

    2007-01-01

    Biomarkers of genotoxicity (DNA damage, measured as tail moment in the Comet assay), neurotoxicity (acetylcholinesterase inhibition, AChE) and general stress (lysosomal membrane stability, LMS) were studied in native and transplanted blue mussels (Mytilus edulis) in coastal areas of western Denmark...... of chemical pollution complex, as seen especially in the variability in results on DNA damage, and also in regard to AChE activity. These investigations further stress the importance of understanding the effects of natural factors (salinity, temperature, water levels, rain and storm events) in correct...

  9. A Comprehensive Strategy to Evaluate Compatible Stability of Chinese Medicine Injection and Infusion Solutions Based on Chemical Analysis and Bioactivity Assay.

    Science.gov (United States)

    Li, Jian-Ping; Liu, Yang; Guo, Jian-Ming; Shang, Er-Xin; Zhu, Zhen-Hua; Zhu, Kevin Y; Tang, Yu-Ping; Zhao, Bu-Chang; Tang, Zhi-Shu; Duan, Jin-Ao

    2017-01-01

    Stability of traditional Chinese medicine injection (TCMI) is an important issue related with its clinical application. TCMI is composed of multi-components, therefore, when evaluating TCMI stability, several marker compounds cannot represent global components or biological activities of TCMI. Till now, when evaluating TCMI stability, method involving the global components or biological activities has not been reported. In this paper, we established a comprehensive strategy composed of three different methods to evaluate the chemical and biological stability of a typical TCMI, Danhong injection (DHI). UHPLC-TQ/MS was used to analyze the stability of marker compounds (SaA, SaB, RA, DSS, PA, CA, and SG) in DHI, UHPLC-QTOF/MS was used to analyze the stability of global components (MW 80-1000 Da) in DHI, and cell based antioxidant capability assay was used to evaluate the bioactivity of DHI. We applied this strategy to assess the compatible stability of DHI and six infusion solutions (GS, NS, GNS, FI, XI, and DGI), which were commonly used in combination with DHI in clinic. GS was the best infusion solution for DHI, and DGI was the worst one based on marker compounds analysis. Based on global components analysis, XI and DGI were the worst infusion solutions for DHI. And based on bioactivity assay, GS was the best infusion solution for DHI, and XI was the worst one. In conclusion, as evaluated by the established comprehensive strategy, GS was the best infusion solution, however, XI and DGI were the worst infusion solutions for DHI. In the compatibility of DHI and XI or DGI, salvianolic acids in DHI would be degraded, resulting in the reduction of original composition and generation of new components, and leading to the changes of biological activities. This is the essence of instability compatibility of DHI and some infusion solutions. Our study provided references for choosing the reasonable infusion solutions for DHI, which could contribute the improvement of safety

  10. DNA damage, acetylcholinesterase activity and lysosomal stability in native and transplanted mussels (Mytilus edulis) in areas close to coastal chemical dumping sites in Denmark

    DEFF Research Database (Denmark)

    Rank, J.; Lehtonen, K. K.; Strand, J.

    2007-01-01

    of chemical pollution complex, as seen especially in the variability in results on DNA damage, and also in regard to AChE activity. These investigations further stress the importance of understanding the effects of natural factors (salinity, temperature, water levels, rain and storm events) in correct......Biomarkers of genotoxicity (DNA damage, measured as tail moment in the Comet assay), neurotoxicity (acetylcholinesterase inhibition, AChE) and general stress (lysosomal membrane stability, LMS) were studied in native and transplanted blue mussels (Mytilus edulis) in coastal areas of western Denmark...... potentially affected by anthropogenic pollution originating from chemical dumping sites. The results indicate responses to pollution in all the biomarkers applied at the suspected areas, but the results were not consistent. Seasonal fluctuations in exposure situations at the study sites make interpretation...

  11. Galvanic replacement-free deposition of Au on Ag for core-shell nanocubes with enhanced chemical stability and SERS activity.

    Science.gov (United States)

    Yang, Yin; Liu, Jingyue; Fu, Zheng-Wen; Qin, Dong

    2014-06-11

    We report a robust synthesis of Ag@Au core-shell nanocubes by directly depositing Au atoms on the surfaces of Ag nanocubes as conformal, ultrathin shells. Our success relies on the introduction of a strong reducing agent to compete with and thereby block the galvanic replacement between Ag and HAuCl4. An ultrathin Au shell of 0.6 nm thick was able to protect the Ag in the core in an oxidative environment. Significantly, the core-shell nanocubes exhibited surface plasmonic properties essentially identical to those of the original Ag nanocubes, while the SERS activity showed a 5.4-fold further enhancement owing to an improvement in chemical enhancement. The combination of excellent SERS activity and chemical stability may enable a variety of new applications.

  12. Chemical vapour deposition at atmospheric pressure of graphene on molybdenum foil: Effect of annealing time on characteristics and corrosion stability of graphene coatings

    International Nuclear Information System (INIS)

    Naghdi, Samira; Jevremović, Ivana; Mišković-Stanković, Vesna; Rhee, Kyong Yop

    2016-01-01

    Highlights: • Atmospheric pressure chemical vapor deposition of graphene on molybdenum foils. • Quality and domain size of graphene layers increased with longer annealing times. • The number of graphene layers decreased with longer annealing times. • Graphene coatings on molybdenum foils exhibited corrosion inhibitive properties. - Abstract: In this work, the effect of pre-annealing of Mo substrate on the quality of graphene layers grown by chemical vapour deposition was investigated by X-ray diffraction, X-ray photoelectron spectroscopy, and Raman spectroscopy. Moreover, different electrochemical techniques were employed to investigate the corrosion stability of the graphene coated Mo in 0.1 M NaCl. Longer annealing time resulted in less defective graphene coatings with fewer layers. Graphene coating on the annealed Mo provided better protection against corrosion during the initial exposure times, while after prolonged exposure times, both graphene coatings on annealed and non-annealed Mo exhibited nearly the same corrosion inhibitive properties.

  13. A Study of the Stability and Characterization Plutonium Dioxide and Chemical Characterization [of] Rocky Flats and Los Alamos Plutonium-Containing Incinerator Ash

    International Nuclear Information System (INIS)

    Ray, A.K.; Boettger, J.C.; Behrens, Robert G.

    1999-01-01

    In the presentation ''A Study of the Stability and Characterization of Plutonium Dioxide'', the authors discuss their recent work on actinide stabilities and characterization, in particular, plutonium dioxide PuO 2 . Earlier studies have indicated that PuO 2 has the fluorite structure of CaF 2 and typical oxide semiconductor properties. However, detailed results on the bulk electronic structure of this important actinide oxide have not been available. The authors have used all-electron, full potential linear combinations Gaussian type orbitals fitting function (LCGTO-FF) method to study PuO 2 . The LCGTO-FF technique characterized by its use of three independent GTO basis sets to expand the orbitals, charge density, and exchange-correlation integral kernels. Results will be presented on zero pressure using both the Hedin-Lundquist local density approximation (LDA) model or the Perdew-Wang generalized gradient approximation (GGA) model. Possibilities of different characterizations of PuO 2 will be explored. The paper ''Chemical Characterization Rocky Flats and Los Alamos Plutonium-Containing Incinerator Ash'' describes the results of a comprehensive study of the chemical characteristics of virgin, calcined and fluorinated incinerator ash produced at the Rocky Flats Plant and at the Los Alamos National Laboratory prior to 1988. The Rocky Flats and Los Alamos virgin, calcined, and fluorinated ashes were also dissolved using standard nitrate dissolution chemistry. Corresponding chemical evaluations were preformed on the resultant ash heel and the results compared with those of the virgin ash. Fluorination studies using FT spectroscopy as a diagnostic tool were also performed to evaluate the chemistry of phosphorus, sulfur, carbon, and silicon containing species in the ash. The distribution of plutonium and other chemical elements with the virgin ash, ash heel, fluorinated ash, and fluorinated ash heel particulates were studied in detail using microprobe analysis. Some

  14. Heat and mass transfer in turbulent chemically nonequilibrium flow in the tube with boundary second kind conditions. The section with the stabilized heat and mass transfer

    International Nuclear Information System (INIS)

    Kritsuk, E.L.; Mishina, L.V.; Shegidevich, L.N.

    1986-01-01

    The hydrodynamically stabilized chemically nonequilibrium turbulent flow in a tube with the inert impermeable surface and constant specific heat flow on the wall is considered. The reversible homogeneous reaction of nitrogen dioxide dissociation 2NO 2 ↔ 2NO+O 2 takes place in the flow. Chemically equilibrium flow with homogeneous profile of temperature and concentration arrives into the channel inlet. After application of simplifying assumptions, the expressions for characteristics of heat and mass transfer have been written down, which are valid in the whole range of the flow parameter variation from frozen up to chemically equilibrium flow. An integral transformation method is suggested for a radial coordinate which allows a wall region to be extended, thereby essentially extending the step of integration. A solution in quadratures has been obtained for the heat and mass transfer problem in an inert fluid flow for the developed process section. The elimination method has been employed to solve the boundary-value second-kind problem for the function governing heat and mass transfer in a chemically nonequilibrium turbulent flow over the developed heat and mass transfer section. The results of calculations are presented

  15. Chemical stability of diphenhydramine hydrochloride from an elixir and lidocaine hydrochloride from a viscous solution when mixed together.

    Science.gov (United States)

    Gupta, Vishnu D

    2006-01-01

    The stability of diphenhydramine hydrochloride (from an elixir) and lidocaine hydrochloride (from a viscous solution) in a mixture (1:1) was studied using a stability-indicating high-peformance liquid chromatographic assay method. The concentrations of the drugs were related directly to peak heights and the percent relative standard deviations based on five injections were 1.4 for diphenhydramine and 1.3 for lidocaine. The products of hydrolysis from the both the drugs and a number of excipients present in the dosage forms did not interfere with the developed assay procedure. The mixture was stable for at least 21 days when stored in amber-colored bottles at room temperature. The pH value of the mixture remained constant, and the physical appearance did not change during the study period.

  16. Determination of Conditional Stability Constants for Metal Ions with Humic Acid using Chemically Immobilised Humic Acid on Silica Gel

    Energy Technology Data Exchange (ETDEWEB)

    Szabo, G.; Guszi, J. [Frederic Joliot-Curie' National Research Inst. for Rad iobiology and Radiohygiene, Budapest, H-1775 (Hungary)]. e-mail: szabogy@hp.osski.hu; Miyajima, T. [Dept. of Chemistry, Faculty of Science and Engineering, Saga Univ ., 1-Honjo, Saga (Japan); Geckeis, H. [Forschungszentrum Karlsruhe, Inst. fuer Nuk leare Entsorgung, 76021 Karlsruhe (Germany); Reiller, P. [Commissariat a l' Energie A tomique, CE Saclay, Laboratoire de Speciation des Radionucleides et des Molecule s, F-91191 Gif-sur-Yvette (France); Bulman, R.A. [Radiation Protection Div., Health Protection Agency, Chilton, Didcot (United Kingdom)

    2007-06-15

    Limitations on aqueous solution chemistries of humic acid, and also hydrolysis of some cationic species, restrict measurement of conditional stability constants of 4f- and 5f-series elements as humate complexes. Reported log {beta} values are determined by using non-linear regression binding isotherms, of Am(III) and Th(IV), and also Ag(I) and Sr(II), bound by a humic acid composite.

  17. Chemical composition and oxidative stability of jussara (Euterpe edulis M.) oil extracted by cold and hot mechanical pressing

    International Nuclear Information System (INIS)

    Da Cunha, A.L.A.; Freitas, S.P.; Godoy, R.L.O.; Cabral, L.M.C.; Tonon, R.V.

    2017-01-01

    The aim of this work was to evaluate the effect of mechanical pressing on jussara oil yield, oxidative stability and carotenoid profile with or without heat application. Firstly, jussara pulp was centrifuged for juice extraction, and the resulting cake was dried until reaching 10% moisture content. Then, oil extraction was performed in an expeller press at 25 ºC (cold pressing) and at 50 ºC (hot pressing). The process performance was evaluated by the oil yield, and the crude jussara oil was characterized for fatty acid composition, acid value, carotenoid profile and oxidative stability. Jussara oil contained 74% unsaturated fatty acids, mainly oleic and linoleic acids (48% and 24%, respectively). The oil yield was almost twice as high for the hot process as compared to the cold one. Additionally, hot pressing resulted in 25% higher total carotenoid content as compared to cold pressing, with β-carotene as the most abundant one. Hot and cold pressing showed no difference in oil oxidative stability and fatty acid composition. [es

  18. Formulating orange oil-in-water beverage emulsions for effective delivery of bioactives: Improvements in chemical stability, antioxidant activity and gastrointestinal fate of lycopene using carrier oils.

    Science.gov (United States)

    Meroni, Erika; Raikos, Vassilios

    2018-04-01

    The influence of carrier oil type on the chemical stability, antioxidant properties and bioaccessibility of lycopene in orange oil-in-water beverage emulsions was investigated. The emulsions were formulated with orange oil (A), which was partially (50%) replaced with tributyrin (B) or corn oil (C) because of their distinctively different fatty acid composition. The addition of corn oil enhanced the physical stability of the beverage during chilled storage by inhibiting Ostwald ripening. The formation of oxidation products was insignificant after storage for 28 days at 4 °C, regardless the type of added oil. Lycopene was more susceptible to chemical degradation in the presence of unsaturated, long chain triglycerides and the retention followed the order: A (87.94%), B (64.41%) and C (57.39%). Interestingly, bioaccessibility of lycopene was significantly lower for emulsions formulated with 50% corn oil as opposed to 100% orange oil as indicated by the simulated in vitro gastric digestion model. Copyright © 2018 Elsevier Ltd. All rights reserved.

  19. Role of post-sulfonation of poly(ether ether sulfone) in proton conductivity and chemical stability of its proton exchange membranes for fuel cell

    Energy Technology Data Exchange (ETDEWEB)

    Unveren, Elif Erdal; Erdogan, Tuba; Inan, Tulay Y. [Chemistry Institute, TUBITAK Marmara Research Center, 41470, Gebze, Kocaeli (Turkey); Celebi, Serdar S. [Professor Emeritus, Chemical Engineering Department, Hacettepe University, 06800, Beytepe, Ankara (Turkey)

    2010-04-15

    Commercially available poly(ether ether sulfone), PEES, was directly sulfonated using concentrated sulfuric acid at low temperatures by minimizing degradation during sulfonation. The sulfonation reaction was performed in the temperature range of 5-25 C. Sulfonated polymers were characterized by FTIR, {sup 1}H NMR spectroscopy and ion exchange capacity (IEC) measurements. Degradation during sulfonation was investigated by measuring intrinsic viscosity, glass transition temperature and thermal decomposition temperature of sulfonated polymers. Sulfonated PEES, SPEES, membranes were prepared by solvent casting method and characterized in terms of IEC, proton conductivity and water uptake. The effect of sulfonation conditions on chemical stability of membranes was also investigated via Fenton test. Optimum sulfonation condition was determined to be 10 C with conc. H{sub 2}SO{sub 4} based on the characteristics of sulfonated polymers and also the chemical stability of their membranes. SPEES membranes exhibited proton conductivity up to 185.8 mS cm{sup -1} which is higher than that of Nafion 117 (133.3 mS cm{sup -1}) measured at 80 C and relative humidity 100%. (author)

  20. Oxidative stability, chemical composition and organoleptic properties of seinat (Cucumis melo var. tibish) seed oil blends with peanut oil from China.

    Science.gov (United States)

    Siddeeg, Azhari; Xia, Wenshui

    2015-12-01

    Seinat seed oil was blended with peanut oil for the enhancement of stability and chemical characteristics of the blend. The physicochemical properties (relative density, refractive index, free fatty acids, saponification value, iodine value and peroxide value) of seinat seed and peanut oil blends in ratios 95:5, 85:15, 30:70 and 50:50 proportions were evaluated, as well as oxidative stability index, deferential scanning calorimetric (DSC) characteristics and tocopherols content. Results of oil blend showed that there was no negative effect by the addition of seinat seed oil to peanut oil and also had decreased percentages of all saturated fatty acids except stearic acid, conversely, increased the levels of unsaturated fatty acids. As for the sensory evaluation, the panelist results showed that seinat seed oil blends had no significant differences (p blending of seinat seed oil with peanut oil had also increased the stability and tocopherols content. As Sudan is the first producer of seinat oil, blending of seinat seed oil with traditional oil like quality, and may decrease the consumption of other expensive edible oils.

  1. Influence of different sugar cryoprotectants on the stability and physico-chemical characteristics of freeze-dried 5-fluorouracil plurilamellar vesicles

    Directory of Open Access Journals (Sweden)

    Mohamed Mahmoud Nounou

    2005-07-01

    Full Text Available Lyophilization increases the shelf-life of liposomes by preserving it in a dry form as lyophilized cake to be reconstituted with water immediately prior to administration. Aiming at increasing stability and availability of 5-Fluorouracil liposomal products, 5-Fluorouacil Stable Plurilamellar Vesicles were prepared. Freeze dried liposomal dispersions were prepared with or without cryoprotectants. The cryoprotectants used were glucose, mannitol or trehalose in 1, 2 and 4 grams per gram phospholipids. The results showed that lyophilized cake of liposomes without cryoprotectants was compact and difficult to reconstitute, in comparison with fluffy cakes which reconstituted easily and quickly when using cryoprotectants. The percentage of 5-Fluorouracil retained in liposomes freeze-dried without cryoprotectants was 18.29% ± 0.96% and the percentage of 5-Fluorouracil retained in stable plurilamellar vesicles was 31.22% ± 0.62% using 4 grams trehalose as cryoprotectant per gram of lipid. Physico-chemical and release stability studies showed superior potentials of the lyophilized product after reconstitution in comparison to dispersion product. It may be concluded that all tested sugars have cryoprotectant effects that stabilized liposomes in the freeze dried state, where trehalose offered the most superior cryoprotectant effect for freeze dried 5-fluorouracil liposomes.

  2. Chemical and radiation stability of a proprietary cesium ion exchange material manufactured from WWL membrane and SuperLig reg-sign 644

    International Nuclear Information System (INIS)

    Brown, G.N.; Carson, K.J.; DesChane, J.R.; Elovich, R.J.; Berry, P.K.

    1996-09-01

    Pretreatment of nuclear process wastes for ion exchange removal of Cs and other radionuclides is one way to minimize amount of high-level radioactive waste at Hanford. This study evaluated Cs-selective SuperLig reg-sign 644 (IBC Advanced Technologies, American Fork UT) entrapped in a proprietary WWL web membrane (3M) for chemical/radiation stability in simulated caustic neutralized current acid waste (NCAW), 0.5M HNO 3 , water, and air. After exposure up to 2.0E+09 rad, the material was evaluated for Cs uptake in 5M sodium NCAW simulants with varying Cs contents. Radiolytic stability appears to be sufficient for ion exchange pretreatment of radioactive Cs: essentially no decrease in Cs selectivity or loading (Kd) was observed during 60 Cs gamma irradiation in water or 0.5M HNO 3 up to 1.0E+09 rad. Cs Kd decreased by a factor of 2 after 2.0E+09 rad exposure. Cs Kd did not change during irradiation in 5M NCAW or ambient air up to 1.0E+08 rad, but decreased by more than an order of magnitude between 1.0E+08 and 2.0E+09 rad (not typical of process conditions). Chemical stability under caustic conditions is lower than in air or under neutral/acidic conditions. Results indicate that this material is less stable in caustic solution irrespective of radiation exposure. Samples of the membrane retained their physical form throughout the entire experiment and were only slightly brittle after exposure to 2.0E+09 rad. (The material evaluated was a finely ground (400 mesh) particulate engineered to form a polymeric fiber (WWL), not the macroscopic form of SuperLig reg-sign 644 resin (20 to 50 mesh).)

  3. Electrical conductivity and chemical stability of BaCe0·8−xAxGd0 ...

    Indian Academy of Sciences (India)

    −1 in air at 1073 K. BaCe0·7In0·1Gd0·2O3−δ and BaCe0·7Zr0·1Gd0·2O3−δ ceramics exhibit an ... cells convert chemical energy directly into electrical energy and their ... peratures in the presence of CO2 and water vapour (Haile. 2003 ...

  4. An evaluation of the effectiveness of a chemical additive based on sodium benzoate, potassium sorbate, and sodium nitrite on the fermentation and aerobic stability of corn silage.

    Science.gov (United States)

    Kung, Limin; Smith, Megan L; Benjamim da Silva, Erica; Windle, Michelle C; da Silva, Thiago C; Polukis, Stephanie A

    2018-04-11

    We evaluated the effectiveness of an additive comprising sodium benzoate, potassium sorbate, and sodium nitrite (SSL) as active ingredients for its ability to improve the aerobic stability of corn silages made in North America. In experiment 1, treatment with SSL (1.5 and 2.0 L/t) on whole-plant corn (WPC) was compared with treatment with an additive containing buffered propionic acid and citric acid (BPA; 2 L/t) on corn harvested at 32 and 38% DM and ensiled for 120 d. Silage treated with BPA was higher in ammonia-N and propionic acid relative to other treatments. Treatments with all of the additives had numerically, but not statistically, fewer yeasts compared with untreated silage. Both application rates of SSL resulted in lower concentrations of ethanol compared with untreated and BPA silages. Treatment with BPA improved the aerobic stability of silages compared with untreated silage, but the effect from SSL was markedly greater. In experiment 2, WPC was untreated or treated with 2 or 3 L of SSL/t or a microbial inoculant containing Enterococcus faecium M74, Lactobacillus plantarum CH6072, and Lactobacillus buchneri LN1819 (final total lactic acid bacteria application rate of 150,000 cfu/g of fresh forage). Silages were air stressed for 24 h at 28 and 42 d of storage and ensiled for 49 d before opening. Inoculation had no effect on acid end products, ethanol, number of yeasts, or aerobic stability compared with other treatments. Treatment with SSL decreased the amount of ethanol, had no effect on number of yeasts, and improved aerobic stability in a dose-dependent manner compared with other treatments. In experiment 3, WPC was untreated or treated with 2 L of SSL/t and ensiled for 5, 15, and 30 d. Treatment with SSL resulted in silage with fewer yeasts and lower concentrations of ethanol after all times of ensiling compared with untreated silage. In addition, SSL improved aerobic stability after each period of ensiling, but the effect was more at 15 and 30 d

  5. Long-term urine biobanking: storage stability of clinical chemical parameters under moderate freezing conditions without use of preservatives.

    Science.gov (United States)

    Remer, Thomas; Montenegro-Bethancourt, Gabriela; Shi, Lijie

    2014-12-01

    To examine the long-term stability and validity of analyte concentrations of 21 clinical biochemistry parameters in 24-h urine samples stored for 12 or 15 yr at -22°C and preservative free. Healthy children's 24-h urine samples in which the respective analytes had been measured shortly after sample collection (baseline) were reanalyzed. Second measurement was performed after 12 yr (organic acids) and 15 yr (creatinine, urea, osmolality, iodine, nitrogen, anions, cations, acid-base parameters) with the same analytical methodology. Paired comparisons and correlations between the baseline and repeated measurements were done. Recovery rates were calculated. More than half of the analytes (creatinine, urea, iodine, nitrogen, sodium, potassium, magnesium, calcium, ammonium, bicarbonate, citric & uric acid) showed measurement values after >10 yr of storage not significantly different from baseline. 15 of the 21 parameters were highly correlated (r=0.99) between baseline and second measurement. Poorest correlation was r=0.77 for oxalate. Recovery ranged from 73% (oxalate) to 105% (phosphate). Our results suggest high long-term stability and measurement validity for numerous clinical chemistry parameters stored at -22°C without addition of any urine preservative. Prospective storage of urine aliquots at -22°C for periods even exceeding 10 yr, appears to be an acceptable and valid tool in epidemiological settings for later quantification of several urine analytes. Copyright © 2014 The Canadian Society of Clinical Chemists. Published by Elsevier Inc. All rights reserved.

  6. Assumed non-persistent environmental chemicals in human adipose tissue; matrix stability and correlation with levels measured in urine and serum.

    Science.gov (United States)

    Artacho-Cordón, F; Arrebola, J P; Nielsen, O; Hernández, P; Skakkebaek, N E; Fernández, M F; Andersson, A M; Olea, N; Frederiksen, H

    2017-07-01

    The aim of this study was to (1) optimize a method for the measurement of parabens and phenols in adipose tissue, (2) evaluate the stability of chemical residues in adipose tissue samples, and (3) study correlations of these compounds in urine, serum, and adipose tissue. Samples were obtained from adults undergoing trauma surgery. Nine phenols and seven parabens were determined by isotope diluted TurboFlow-LC-MS/MS. The analytical method showed good accuracy and precision. Limits of detection (LOD) for parabens and phenols ranged from 0.05 to 1.83ng/g tissue. Good recovery rates were found, even when biological samples remained defrosted up to 24h. Benzophenone-3 (BP-3; range of values: 70% of adipose tissue samples, while bisphenol-A (BPA; 40% of adipose tissue samples. In general, levels were similar between adipose tissue and serum, while a correlation between adipose tissue and urine was only found for BP-3. In conclusion, adipose tissue samples in this study were found to contain environmental chemicals considered to be non-persistent, whose levels were weakly or not at all correlated with the urine burden. Therefore, adipose tissue may potentially provide additional information to that obtained from other biological matrices. Further investigations are warranted to explore whether adipose tissue might be a suitable matrix for assessment of the consequences for human health of mid/long-term exposure to these chemicals. Copyright © 2017 Elsevier Inc. All rights reserved.

  7. Incorporation of low energy activated nitrogen onto HOPG surface: Chemical states and thermal stability studies by in-situ XPS and Raman spectroscopy

    Science.gov (United States)

    Chandran, Maneesh; Shasha, Michal; Michaelson, Shaul; Hoffman, Alon

    2016-09-01

    In this paper we report the chemical states analysis of activated nitrogen incorporated highly oriented pyrolytic graphite (HOPG) surface under well-controlled conditions. Nitrogen incorporation is carried out by two different processes: an indirect RF nitrogen plasma and low energy (1 keV) N2+ implantation. Bonding configuration, concentration and thermal stability of the incorporated nitrogen species by aforesaid processes are systematically compared by in-situ X-ray photoelectron spectroscopy (XPS). Relatively large concentration of nitrogen is incorporated onto RF nitride HOPG surface (16.2 at.%), compared to N2+ implanted HOPG surface (7.7 at.%). The evolution of N 1s components (N1, N2, N3) with annealing temperature is comprehensively discussed, which indicates that the formation and reorganization of local chemical bonding states are determined by the process of nitridation and not by the prior chemical conditioning (i.e., amorphization or hydrogenation) of the HOPG surface. A combined XPS and Raman spectroscopy studies revealed that N2+ implantation process resulted in a high level of defects to the HOPG surface, which cannot be annealed-out by heat treatment up to 1000 °C. On the other hand, the RF nitrogen plasma process did not produce a high level of surface defects, while incorporating nearly the same amount of stable nitrogen species.

  8. 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.

  9. Final report of the Buffer Mass Test - Volume 3: Chemical and physical stability of the buffer materials

    International Nuclear Information System (INIS)

    Pusch, R.

    1985-11-01

    The Buffer Mass Test offered a possibility to investigate whether chemical changes took place in the smectite component at heating to 125 degrees C for about one year. The alterations that could possibly take place were a slight charge change in the crystal lattice with an associated precipitation of silica compounds, and a tendency of illite formation. The analysis showed that there were indications of both but to such a slight extent that the processes could not have affected the physical properties, which was also demonstrated by determining the swelling pressure and the hydraulic conductivity. The BMT also showed that the erodibility of bentonite-based buffer materials is less than or about equal to what can be expected on theoretical grounds. (author)

  10. Bitumen coating as a tool for improving the porosity and chemical stability of simulated cement-waste forms

    International Nuclear Information System (INIS)

    Saleh, H.M.

    2010-01-01

    Coating process of simulated cement-based waste form with bitumen was evaluated by performing physical and chemical experimental tests. X-ray diffraction (X-RD), Fourier transform infrared spectroscopy (FT-IR) and electron microscope investigations were applied on coated and non-coated simulated waste forms. Experimental results indicated that coating process improved the applicable properties of cement-based waste form such as porosity and leachability. Diffusion coefficients and leach indecies of coated specimens were calculated and show acceptable records. It could be stated that coating cemented waste form by bitumen emulsion, isolate the radioactive contaminants, thus reduces their back release to surrounding and in consequently save the environment proper and safe

  11. Improved stability of titanium based boron-doped chemical vapor deposited diamond thin-film electrode by modifying titanium substrate surface

    International Nuclear Information System (INIS)

    Lim, P.Y.; Lin, F.Y.; Shih, H.C.; Ralchenko, V.G.; Varnin, V.P.; Pleskov, Yu.V.; Hsu, S.F.; Chou, S.S.; Hsu, P.L.

    2008-01-01

    The film quality and electrochemical properties of BDD (boron-doped diamond) thin films grown by hot-filament chemical vapor deposition technique on titanium substrates that had been subjected to a range of pre-treatment processes were evaluated. The pre-roughened Ti-substrates are shown to support more adherent BDD films. It is evident that acid-etching the Ti-substrate involves surface hydrogenation that enhances nucleation and formation of diamond thereon. The prepared BDD film exhibits wide potential window and electrochemical reversibility. It also demonstrated a better long-term electrochemical stability based on the low variation in voltametric background current upon the exposing of the electrodes to repeated cycles of electrochemical metal deposition/stripping process

  12. The effect of γ-ray irradiation on the adsorption properties and chemical stability of AMP/SiO2 towards Cs(I) in HNO3 solution

    International Nuclear Information System (INIS)

    Xiaoxia Zhang; Yan Wu; Yuezhou Wei; Guangxi University, Nanning

    2016-01-01

    Silica based ammonium molybdophosphate (AMP/SiO 2 ) adsorbent was used to remove Cs(I) from HNO 3 solution. The adsorbent with different absorbed dose (0-300 kGy) was characteristed by X-ray power diffraction. The adsorption data against different γ-ray absorbed doses were analyzed by the Langmuir isotherm. The adsorption capacity decreased slightly from 23.22 to 22.37 mg/g with the increase of the absorbed dose. The breakthrough properties of Cs(I) were conducted using column packed with AMP/SiO 2 before and after irradiation. The chemical stability of AMP/SiO 2 at 300 kGy absorbed dose in 3 mol/L (M) HNO 3 was excellent. (author)

  13. Influence of alumina phases on the molybdenum adsorption capacity and chemical stability for {sup 99}Mo/{sup 99m}Tc generators columns

    Energy Technology Data Exchange (ETDEWEB)

    Guedes-Silva, Cecilia C.; Ferreira, Thiago dos Santos; Paula, Carolina M. de; Otubo, Larissa, E-mail: cecilia.guedes@ipen.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil); Carvalho, Flavio M.S. [Universidade de Sao Paulo (IGC/USP), SP (Brazil). Instituto de Geociencias

    2016-07-15

    Technetium-{sup 99m} is the clinically most used radionuclide worldwide. Although many techniques can be applied to separate {sup 99}Mo and {sup 99m}Tc, the most commonly used method is the column chromatography with alumina as stationary phase. However, the alumina nowadays used has limited adsorption capacity of molybdate ions which implies the need to develop or improve materials to produce high specific activity generators. In this paper, alumina was obtained by a solid state method and heat treatments at different conditions. The powders had a microstructure with porous particles of γ, δ, θ and α-Al{sub 2}O{sub 3} phases as well as specific surface area between 36 and 312 m{sup 2} g{sup -1}. Most interesting results were reached by powders calcined at 900 deg C for 5 hours which had high chemical stability and a molybdenum adsorption capacity of 92.45 mg Mo per g alumina. (author)

  14. Chemical stability of CdSe quantum dots in seawater and their effects on a marine microalga

    Energy Technology Data Exchange (ETDEWEB)

    Morelli, Elisabetta, E-mail: elisabetta.morelli@pi.ibf.cnr.it [National Research Council - Institute of Biophysics, Section of Pisa, Via Moruzzi, 1, 56124 Pisa (Italy); Cioni, Patrizia [National Research Council - Institute of Biophysics, Section of Pisa, Via Moruzzi, 1, 56124 Pisa (Italy); Posarelli, Mauro [Italian National Agency for New Technologies, Energy and Sustainable Economic Development, Section of Pisa, Via Moruzzi, 1, 56124 Pisa (Italy); Gabellieri, Edi [National Research Council - Institute of Biophysics, Section of Pisa, Via Moruzzi, 1, 56124 Pisa (Italy)

    2012-10-15

    With the increasing use of nanotechnologies, it is expected that nanomaterials end up in natural aquatic systems, from freshwater to the sea. In this work we studied the chemical behaviour of water-soluble CdSe QDs in seawater and their effects on the marine diatom Phaeodactylum tricornutum, as a model of a biological receptor in the marine environment. We evaluated QD toxicity in terms of growth rate inhibition, oxidative stress and ROS accumulation. In addition, we used the synthesis of phytochelatins (PCs) as a biomarker of the presence of free Cd{sup 2+} ions released from QDs. The optical and chemical characterization demonstrated the propensity of QDs to aggregate after dispersion in raw seawater. In addition, bare CdSe QDs, lacking the ZnS shell, underwent a salinity-dependent degradation process. Short-term exposure experiments showed that the ease of degradation of QDs in seawater correlated with the synthesis of PCs in P. tricornutum cells. Long-term exposure experiments, carried out with the most stable CdSe/ZnS QDs, showed that algae accumulated Cd, but synthesized negligible amounts of PCs. Since the production of PCs is a specific signal of the presence of bioavailable metal ions, our findings suggest that QDs, associated to P. tricornutum cells, did not release PC-inducing metal species. Our data also showed a gradual decrease in algal growth rate at concentrations of QDs higher than 0.5 nM. Measurements of the activity of the antioxidant enzymes showed that superoxide dismutase (SOD) and catalase (CAT) activities were increased by exposure to [QDs] {>=} 0.5 nM, whereas ascorbate peroxidase (APX) and glutathione reductase (GR) activities were not significantly affected. The increase in SOD and CAT activity can be considered a symptom of oxidative stress induced by an enhanced production of ROS. This hypothesis was confirmed by the concomitant increase in the intracellular ROS concentration.

  15. Active packaged lamb with oxygen scavenger/carbon dioxide emitter sachet: physical-chemical and microbiological stability during refrigerated storage

    Directory of Open Access Journals (Sweden)

    Marco Antonio Trindade

    2013-09-01

    Full Text Available Lamb meat has been commercialized in Brazil almost exclusively as a frozen product due to the longer shelf life provided by freezing when compared to refrigeration. However, as a result of the current trend of increased demand for convenience products, a need has emerged for further studies to facilitate the marketing of refrigerated lamb cuts. The aim of the present study was to evaluate the contribution of active packaging technology in extending the shelf life of lamb loins (Longissimus lumborum stored under refrigeration (1±1 ° C when compared to the traditional vacuum packaging. For this purpose, two kinds of sachets were employed: oxygen scavenger sachet and oxygen scavenger/carbon dioxide emitter sachet. Experiments were conducted in three treatments: 1 Vacuum (Control, 2 Vacuum + oxygen scavenger sachet and 3 Vacuum + oxygen scavenger/carbon dioxide emitter sachet. Microbiological (counts of anaerobic psychrotrophs, coliform at 45 ° C, coagulase-positive staphylococci, Salmonella and lactic acid bacteria and physical-chemical (thiobarbituric acid reactive substances, objective color, pH value, water loss from cooking and shear force analyses were carried out weekly for a total storage period of 28 days. The experiment was performed three times for all treatments. Results showed that the lamb meat remained stable with respect to the majority of the evaluated physical and chemical indexes and remained within the standards established by Brazilian legislation for pathogenic microorganisms throughout the storage period in all three packaging systems. However, all treatments presented elevated counts of anaerobic psychrotrophic microorganisms and lactic acid bacteria, reaching values above 10(7 CFU/g at 28 days of storage. Thus, under the conditions tested, neither the oxygen scavenger sachet nor the dual function sachet (oxygen scavenger/carbon dioxide emitter were able to extend the shelf life of refrigerated lamb loin when added to this

  16. The Influence of Propolis as Supplement Diet on Broiler Meat Growth Performance, Carcass Body Weight, Chemical Composition and Lipid Oxidation Stability

    Directory of Open Access Journals (Sweden)

    Peter Haščík

    2015-01-01

    Full Text Available The present experiment was aimed to study the effect of the propolis extract as supplement diet on the broiler chickens growth performance, breast and thigh weights, meat chemical composition and lipid oxidation stability. A total of 120 chicks in one day old, which were divided into 4 groups (n = 30 for 42 days.To the experimental groups were added propolis extract in doses of 200 mg.kg−1 (II, 300 mg.kg−1 (III and 400 mg.kg−1 (IV. At the end of the experiment the results were shown that the body weight gain after 21 and 42 days has been increased and there were found significant differences (P ≤ 0.05 between control and experimental groups also the feed intake has been increased and there were (P ≤ 0.05. The FCR was higher in the control group. The carcass body weight breast and thigh weights were increased and there were no significant differences while, the abdominal fat and liver weights were decreased. No significant difference was occurred on chemical composition of breast and thigh muscles, whereasthe muscle moisture tends to increase and fat content and energy value were decreased. Interestingly, thelipid oxidation stability measured as TBARS during the freezing storage for 6 months has been decreasedmalondialdehyde (MDA in the experimental groups and there were found significant (P ≤ 0.05 in the breast musclesbetween control group and experimental groups. From the present study were concluded after administration the propolis extract that broilergrowth performance has been increased and the lipid oxidation (MDA during the freezing storage (−18 °C have been decreased.

  17. Pharmaceutical optimization of lipid-based dosage forms for the improvement of taste-masking, chemical stability and solubilizing capacity of phenobarbital.

    Science.gov (United States)

    Monteagudo, Ezequiel; Langenheim, Mariana; Salerno, Claudia; Buontempo, Fabián; Bregni, Carlos; Carlucci, Adriana

    2014-06-01

    Microemulsions (MEs) and self-emulsifying drug delivery systems (SEEDS) containing phenobarbital (Phe) were developed to improve its chemical stability, solubilizing capacity and taste-masking in oral liquid dosage forms. Cremophor® RH40 and Labrasol® were used as surfactants for the screening of ME regions, Capmul® MCM L, Captex® 355, Imwitor® 408, Myglyol® 840 and Isopropyl myristate were the oil phases assayed; Transcutol® P, Polyethylene-glycol 400, glycerol, Propylene-glycol and ethanol the cosurfactants. Phe stability assay was carried out (20:4:20:56% and 20:4:35:41% (w/w); surfactant:oily phase:cosurfactant:water) for both surfactants; only one containing ethanol showed significant dismissing in its drug content. Solubility capacity for these selected formulations were also evaluated, an amount between 17 and 58 mg/mL of Phe could be loaded. At last, an optimized ME formulation with Cremophor® RH40 20%, Capmul® MCM L 4%, PEG 400 35% and sucralose 2% (w/w) was chosen in order to optimize taste-masking using an electronic tongue. Strawberry along with banana and tutti-frutti flavors plus mint flavor proved to be the best ones. Labrasol-based pre-concentrates were tested for (micro)emulsifying properties; all of them resulted to behave as SEDDS. In summary, a rationale experimental design conducted to an optimized ME for Phe oral pediatric administration which was able to load 5-fold times the currently used dose (4 mg/mL), with no sign of physical or chemical instability and with improved taste; SEDDS for capsule filling were also obtained. The biopharmaceutical advantages described for these dosage forms encourage furthering in vivo evaluation.

  18. Confinement Effects on Chemical Equilibria: Pentacyano(PyrazineFerrate(II Stability Changes within Nanosized Droplets of Water

    Directory of Open Access Journals (Sweden)

    Teofilo Borunda

    2018-04-01

    Full Text Available Nanoscale confinement is known to impact properties of molecules and we observed changes in the reactivity of an iron coordination complex, pentacyano(pyrazineferrate(II. The confinement of two coordination complexes in a sodium AOT/isooctane reverse micellar (RM water droplet was found to dramatically increase the hydrolysis rate of [Fe(CN5pyz]3− and change the monomer-dimer equilibria between [Fe(CN5pyz]3− and [Fe2(CN10pyz]6−. Combined UV-Vis and 1H-NMR spectra of these complexes in RMs were analyzed and the position of the monomer-dimer equilibrium and the relative reaction times were determined at three different RM sizes. The data show that the hydrolysis rates (loss of pyrazine are dramatically enhanced in RMs over bulk water and increase as the size of the RM decreases. Likewise, the monomer-dimer equilibrium changes to favor the formation of dimer as the RM size decreases. We conclude that the effects of the [Fe(CN5pyz]3− stability is related to its solvation within the RM.

  19. Double dielectric barrier (DBD) plasma-assisted deposition of chemical stabilized nanoparticles on polyamide 6,6 and polyester fabrics

    Science.gov (United States)

    Ribeiro, A. I.; Modic, M.; Cvelbar, U.; Dinescu, G.; Mitu, B.; Nikiforov, A.; Leys, C.; Kuchakova, I.; Vanneste, M.; Heyse, P.; De Vrieze, M.; Carneiro, N.; Souto, A. P.; Zille, A.

    2017-10-01

    The development of new multifunctional textiles containing nanoparticles (NPs) has a special interest in several applications for pharmaceutical and medical products. Cu, Zn and Ag are the most promising antimicrobial NPs, exhibiting strong antibacterial activities. However, most of antimicrobial textiles coated with NPs are not able to perform a controlled release of NPs because of the high degree of aggregation. The aim of this study is to assess the effect of NPs stabilizers such as citrate, alginate and polyvinyl alcohol (PVA) in Cu, Zn and Ag NPs dispersions. The obtained dispersions were used to develop a new class of antibacterial NPs coatings onto polyamide 6,6 (PA66) and polyester fabrics (PES) by Double Dielectric Barrier (DBD) plasma discharge. Dynamic light scattering (DLS) was used to evaluate the best dispersing agent in terms of size, polydispersity index and zeta potential. Coating efficiency was evaluated by SEM, XPS and FTIR. The washing fastness of the coatings developed was also tested. The results show that the best dispersions were obtained using 2.5% of citrate for ZnO, 5% Alginate for Cu and 2.5% alginate for Ag NPs. SEM, XPS and FTIR analysis shows that DBD is an efficient deposition technique only for Ag and Cu NPs and that better perform in PA66 than PES fabric. The DBD deposition in air display similar results in term of NPS deposition of usually more efficient plasma jets using carrier gas such as N2 and Ar.

  20. Lattice parameters and stability of the spinel compounds in relation to the ionic radii and electronegativities of constituting chemical elements.

    Science.gov (United States)

    Brik, Mikhail G; Suchocki, Andrzej; Kamińska, Agata

    2014-05-19

    A thorough consideration of the relation between the lattice parameters of 185 binary and ternary spinel compounds, on one side, and ionic radii and electronegativities of the constituting ions, on the other side, allowed for establishing a simple empirical model and finding its linear equation, which links together the above-mentioned quantities. The derived equation gives good agreement between the experimental and modeled values of the lattice parameters in the considered group of spinels, with an average relative error of about 1% only. The proposed model was improved further by separate consideration of several groups of spinels, depending on the nature of the anion (oxygen, sulfur, selenium/tellurium, nitrogen). The developed approach can be efficiently used for prediction of lattice constants for new isostructural materials. In particular, the lattice constants of new hypothetic spinels ZnRE2O4, CdRE2S4, CdRE2Se4 (RE = rare earth elements) are predicted in the present Article. In addition, the upper and lower limits for the variation of the ionic radii, electronegativities, and their certain combinations were established, which can be considered as stability criteria for the spinel compounds. The findings of the present Article offer a systematic overview of the structural properties of spinels and can serve as helpful guides for synthesis of new spinel compounds.

  1. Chemical and biological assessment of Cd-polluted sediment for land use: The effect of stabilization using chitosan-coated zeolite.

    Science.gov (United States)

    Wen, Jia; Zeng, Guangming

    2018-04-15

    Disposal of dredged sediment contaminated with heavy metals on site or in landfills inevitably causes leaching of metals that generate new environmental problems. In this study, we investigated the effectiveness of stabilizing heavy metal Cd in sediment taken from Dongting Lake, China, using a chitosan-coated zeolite, and assessed the feasibility of reusing the stabilized sediment in river bank soil based on chemical and biological analyses. Results showed that the addition of chitosan-coated zeolite significantly reduced acid-exchangeable Cd by 8% in the dredged sediment and 7% in a sediment-soil mixture. Cadmium leachability was greatly reduced in the amended sediment or sediment-soil mixture. Toxicity bioassay using Eisenia fetida showed the mortality rate of worms reduced by 16% in sediment-soil mixture with a Cd concentration of 550 mg/kg and by 17% under a Cd concentration of 250 mg/kg, both with the addition of modified zeolite. Moreover, assimilation of Cd in the earthworms was decreased by a maximum of 36 mg/kg in the sediment-soil mixture with zeolite amendment. These results indicate that the reuse of Cd-contaminated sediment following chitosan-coated zeolite modification is a feasible option for treating the dredged sediment, and could thus benefit both aquatic and terrestrial systems. Copyright © 2018 Elsevier Ltd. All rights reserved.

  2. Wild blueberry polyphenol-protein food ingredients produced by three drying methods: Comparative physico-chemical properties, phytochemical content, and stability during storage.

    Science.gov (United States)

    Correia, Roberta; Grace, Mary H; Esposito, Debora; Lila, Mary Ann

    2017-11-15

    Particulate colloidal aggregate food ingredients were prepared by complexing wheat flour, chickpea flour, coconut flour and soy protein isolate with aqueous wild blueberry pomace extracts, then spray drying, freeze drying, or vacuum oven drying to prepare dry, flour-like matrices. Physico-chemical attributes, phytochemical content and stability during storage were compared. Eighteen anthocyanins peaks were identified for samples. Spray dried matrices produced with soy protein isolate had the highest concentration of polyphenols (156.2mg GAE/g) and anthocyanins (13.4mg/g) and the most potent DPPH scavenging activity (714.1μmolesTE/g). Spray dried blueberry polyphenols complexed with protein were protected from degradation during 16weeks at 4°C and 20°C. Soy protein isolate more efficiently captured and stabilized wild blueberry pomace phytochemicals than other protein sources. Overall, spray drying the blueberry extracts complexed with protein proved to be an environment-friendly strategy to produce stable functional ingredients with multiple applications for the food industry. Copyright © 2017 Elsevier Ltd. All rights reserved.

  3. Diluting ferric carboxymaltose in sodium chloride infusion solution (0.9% w/v) in polypropylene bottles and bags: effects on chemical stability.

    Science.gov (United States)

    Philipp, Erik; Braitsch, Michaela; Bichsel, Tobias; Mühlebach, Stefan

    2016-01-01

    This study was designed to assess the physicochemical stability of colloidal ferric carboxymaltose solution (Ferinject) when diluted and stored in polypropylene (PP) bottles and bags for infusion. Two batches of ferric carboxymaltose solution (Ferinject) were diluted (500 mg, 200 mg and 100 mg iron in 100 mL saline) in PP bottles or bags under aseptic conditions. The diluted solutions were stored at 30°C and 75%±5% relative humidity (rH) for 72 h, and samples were withdrawn aseptically at preparation and after 24 h, 48 h and 72 h. Multiple parameters were used to test stability-related measures (pH, total iron and iron (II) content, molecular weight range determination, microbial contamination and particles count ≥10 μm). Overall, Ferinject diluted in 0.9% (w/v) NaCl solution and stored in PP bottles and bags was stable within the specifications for the complex and the acceptability limits set for all assays. In both containers, total iron content remained stable, within 10% of the theoretical iron content, and levels of iron (II) remained far below the threshold of acceptability. All preparations were free from sediments, particle numbers were acceptable and there was no microbial contamination. The molecular weight distribution and polydispersity index were also acceptable. Under the tested experimental conditions, colloidal ferric carboxymaltose solution (Ferinject) diluted in saline in PP infusion bottles or bags demonstrated physical and chemical stability for up to 72 h at 30°C and 75% rH. Because of the lack of additional clinical data, when using ferric carboxymaltose, physicians/pharmacists should refer to the dilution and storing recommendations given in the product's summary of product characteristics.

  4. Chemical stability of insulin. 2. Formation of higher molecular weight transformation products during storage of pharmaceutical preparations.

    Science.gov (United States)

    Brange, J; Havelund, S; Hougaard, P

    1992-06-01

    Formation of covalent, higher molecular weight transformation (HMWT) products during storage of insulin preparations at 4-45 degrees C was studied by size exclusion chromatography. The main products are covalent insulin dimers (CID), but in protamine-containing preparations the concurrent formation of covalent insulin-protamine (CIP) products takes place. At temperatures greater than or equal to 25 degrees C parallel or consecutive formation of covalent oligo- and polymers can also be observed. Rate of HMWT is only slightly influenced by species of insulin but varies with composition and formulation, and for isophane (NPH) preparations, also with the strength of preparation. Temperature has a pronounced effect on CID, CIP, and, especially, covalent oligo- and polymer formation. The CIDs are apparently formed between molecules within the hexameric unit common for all types of preparations and rate of formation is generally faster in glycerol-containing preparations. Compared with insulin hydrolysis reactions (see the preceding paper), HMWT is one order of magnitude slower, except for NPH preparations.

  5. The application of Cu/SiO2 catalytic system in chemical mechanical planarization based on the stability of SiO2 sol

    International Nuclear Information System (INIS)

    Li Yan; Liu Yuling; Wang Aochen; Yang Zhixin; Sun Mingbin; Cheng Chuan; Zhang Yufeng; Zhang Nannan

    2014-01-01

    There is a lot of hydroxyl on the surface of nano SiO 2 sol used as an abrasive in the chemical mechanical planarization (CMP) process, and the chemical reaction activity of the hydroxyl is very strong due to the nano effect. In addition to providing a mechanical polishing effect, SiO 2 sol is also directly involved in the chemical reaction. The stability of SiO 2 sol was characterized through particle size distribution, zeta potential, viscosity, surface charge and other parameters in order to ensure that the chemical reaction rate in the CMP process, and the surface state of the copper film after CMP was not affected by the SiO 2 sol. Polarization curves and corrosion potential of different concentrations of SiO 2 sol showed that trace SiO 2 sol can effectively weaken the passivation film thickness. In other words, SiO 2 sol accelerated the decomposition rate of passive film. It was confirmed that the SiO 2 sol as reactant had been involved in the CMP process of copper film as reactant by the effect of trace SiO 2 sol on the removal rate of copper film in the CMP process under different conditions. In the CMP process, a small amount of SiO 2 sol can drastically alter the chemical reaction rate of the copper film, therefore, the possibility that Cu/SiO 2 as a catalytic system catalytically accelerated the chemical reaction in the CMP process was proposed. According to the van't Hoff isotherm formula and the characteristics of a catalyst which only changes the chemical reaction rate with out changing the total reaction standard Gibbs free energy, factors affecting the Cu/SiO 2 catalytic reaction were derived from the decomposition rate of Cu (OH) 2 and the pH value of the system, and then it was concluded that the CuSiO 3 as intermediates of Cu/SiO 2 catalytic reaction accelerated the chemical reaction rate in the CMP process. It was confirmed that the Cu/SiO 2 catalytic system generated the intermediate of the catalytic reaction (CuSiO 3 ) in the CMP process

  6. Effect of water and gluten on physico-chemical properties and stability of ready to eat shelf-stable pasta.

    Science.gov (United States)

    Diantom, Agoura; Carini, Eleonora; Curti, Elena; Cassotta, Fabrizio; D'Alessandro, Alessandro; Vittadini, Elena

    2016-03-15

    A multi-analytical and multi-dimensional approach was used to investigate the effect of moisture and gluten on physico-chemical properties of shelf-stable ready to eat (RTE) pasta. Moisture and frozen water contents were not affected by formulation nor storage time. Hardness and retrograded amylopectin significantly increased during storage in all samples, more markedly in pasta with the lowest moisture content. Higher amounts of water and gluten reduced pasta hardening and contributed to control RTE pasta quality. (1)H FID became steeper in all samples during storage, but no effect of high moisture and gluten levels was observed on the mobility of these protons. Three proton T2 populations were observed (population C, population D and population E). Population C and D were not resolved during all storage. (1)H T2 relaxation time of the most abundant population (population E) shifted to shorter times and the amount of protons increased during storage, more importantly in the samples with lower moisture and gluten content. Copyright © 2015 Elsevier Ltd. All rights reserved.

  7. Color stability, radiopacity, and chemical characteristics of white mineral trioxide aggregate associated with 2 different vehicles in contact with blood.

    Science.gov (United States)

    Guimarães, Bruno Martini; Tartari, Talita; Marciano, Marina Angélica; Vivan, Rodrigo Ricci; Mondeli, Rafael Francisco Lia; Camilleri, Josette; Duarte, Marco Antonio Hungaro

    2015-06-01

    Discoloration of mineral trioxide aggregate (MTA) can be exacerbated by the interaction of the cement with body fluids such as blood. This study aimed to analyze the color alteration, chemical characteristics, and radiopacity of MTA manipulated with 2 different vehicles after immersion in blood or distilled water (DW). MTA mixed with 100% DW or 80% DW/20% propylene glycol (PG) as vehicles were placed into rubber rings and incubated at 37°C and 100% relative humidity until set. Color assessment and scanning electron microscopy/energy-dispersive spectroscopy analysis were performed after setting and repeated after 7, 15, and 30 days after immersion in blood and DW. Statistical analysis for color alteration and radiopacity was performed using nonparametric Kruskal-Wallis and Dunn tests (P vehicle, significantly lower color alterations were observed for all time periods compared with 100% DW when immersed in blood (P media because of loss of bismuth. A decrease in radiopacity was observed over time in all groups, with a statistically significant difference after 30 days for groups DW immersed in blood and 80% DW/20% immersed in both media (P vehicle for MTA results in a lower color alteration when in contact with blood. Copyright © 2015 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

  8. Physico-chemical stability of butorphanol-tramadol and butorphanol-fentanyl patient-controlled analgesia infusion solutions over 168 hours.

    Science.gov (United States)

    Chen, Fuchao; Fang, Baoxia; Li, Peng; Zhu, Xuesong; Zhou, Benhong

    2014-08-01

    This study was to investigate the physical and chemical compatibility of butorphanol with tramadol or fentanyl in 0.9% sodium chloride injections for patient controlled analgesia administration. The solutions were prepared in polyvinyl chloride (PVC) infusion bags and stored without protected from light exposure at room temperature (25 degrees C) or refrigerated (4 degrees C). Over a period of 168 hours, stabilities were determined by visual inspection, pH measurement, and high-pressure liquid chromatography (HPLC) assay of drug concentrations. At both temperatures, admixtures of butorphanol-tramadol and butorphanol-fentanyl were clear in appearance, and no color change or precipitation was observed during the study period. The maximum losses obtained were lower than 5% for the three drugs after 168 hours of storage. The results indicate that, at ambient or refrigerated storage conditions, the drug mixtures of butorphanol-tramadol and butorphanol-fentanyl in 0.9% sodium chloride injections were physically and chemically stable for at least 168 hours when stored in PVC syringes.

  9. Interaction of ionizing radiation with other physical and chemical factors in improving the safety and storage stability of foods

    International Nuclear Information System (INIS)

    Farkas, J.; Adrassy, E.; Nanati, D.; Horti, K.; Meszaros, L.; Reichart, O.

    1998-01-01

    Experiments on the preservation of a vacuum packed, ready to fry, chilled meat product (tenderloin rolls), using the combination of a 2 kGy radiation dose with a reduction in pH and/or a reduction in water activity, and on the fate of Listeria monocytogenes in this product were carried out. Irradiation caused a 1-2 decimal reduction in the aerobic viable cell counts, and a 4 decimal reduction in the Enterobacteriaceae counts. Lactic acid bacteria appeared to be more resistant, and were the dominant component of the microflora during chilled storage. Combination treatments prevented growth of Enterobacteriaceae, even at 10 deg. C refrigeration. The microbial stability of the chilled product at 2 deg. C was extended for at least 5 weeks by the triple combination of a dose of 2 kGy, pH reduction to approximately 5.6 and water activity reduction to about 0.960. The combined preserved product proved to be acceptable, both sensorially and from the point of view of the thiobarbituric acid values. The ascorbic acid (as the acidulant) and Na lactate (as the humectant) additives considerably reduced the radiolytic loss of thiamine. The Listeria inoculum survived well in the chilled, non-irradiated product, but diminished by 2 log cycles as a result of irradiation; it tended to decrease even further during post-irradiation storage. In model studies, the radiation survivors of L. monocytogenes showed significantly increased salt and pH sensitivities and an increased minimum temperature for growth in tryptic phosphate broth media, but were less sensitized when recovering in brain heat infusion broth media. A reduction in pH resulted in an increase in not only the apparent lag phase of growth of this test organism but also in the lag phase ratios between the irradiated and non-irradiated populations. The predictive mathematical equations that describe the combined effect of hydrogen ion and salt concentrations on the growth parameters at 30 deg. C were constructed for

  10. The fate of Mercury in Arctic regions: New understanding of atmospheric chemical processes and mercury stability in snow.

    Science.gov (United States)

    Steffen, A.; Ferrari, C.; Dommergue, A.; Scherz, T.; Lawson, G.; Leiatch, R.

    2006-12-01

    Mercury is a known toxic pollutant in the Arctic environment. Atmospheric mercury depletion events (AMDEs) have been studied in the Arctic since 1995. While advances in understanding this newly discovered cycling of mercury in the atmosphere have been made, much of the chemistry and the impact of this annually reoccurring event to the Arctic ecosystem are not well understood. Four years of continuous measurements at Alert, Canada of so-called reactive gaseous mercury (RGM) and mercury associated to particles (PHg) coupled with ongoing snow sampling have produced new information on the atmospheric chemistry and deposition of these mercury species to the Arctic. A distinct pattern during the springtime period in the distribution of these atmospheric mercury species has emerged. This pattern is characterized by the predominance of PHg concentration at the onset of the AMDEs. During the latter part of the AMDE season, there is an obvious swicth in the speciation of mercury to RGM as the main component during AMDEs. This swicth from PHg to RGM is clearly linked to a significant increase of mercury in the snow. In addition, concentrations of PHg are clearly linked with particles in the air that are primarily associated with Arctic haze. Recently, similar results have also been observed in Ny-Alesund (Svalbard). Further observations indicate that once deposited, the deposited mercury appears to evolve chemically in the snow. This change in mercury may impact the transfer of mercury to the environment during snow melt. These first time observed links between atmospheric conditions and subsequent deposition of mercury may help to ascertain the conditions throughout the Arctic as to when significant deposition of mercury will occur. It is proposed that should the concentration of atmospheric particles increase in the Arctic due to long range transport from emission sources, an increase in the deposition of mercury to this environment will increase during the springtime

  11. Metalorganic chemical vapor deposition growth and thermal stability of the AlInN/GaN high electron mobility transistor structure

    International Nuclear Information System (INIS)

    Yu, Hongbo; Ozturk, Mustafa; Demirel, Pakize; Cakmak, Huseyin; Bolukbas, Basar; Caliskan, Deniz; Ozbay, Ekmel

    2011-01-01

    The Al x In 1−x N barrier high electron mobility transistor (HEMT) structure has been optimized with varied barrier composition and thickness grown by metalorganic chemical vapor deposition. After optimization, a transistor structure comprising a 7 nm thick nearly lattice-matched Al 0.83 In 0.17 N barrier exhibits a sheet electron density of 2.0 × 10 13 cm −2 with a high electron mobility of 1540 cm 2 V −1 s −1 . An Al 0.83 In 0.17 N barrier HEMT device with 1 µm gate length provides a current density of 1.0 A mm −1 at V GS = 0 V and an extrinsic transconductance of 242 mS mm −1 , which are remarkably improved compared to that of a conventional Al 0.3 Ga 0.7 N barrier HEMT. To investigate the thermal stability of the HEMT epi-structures, post-growth annealing experiments up to 800 °C have been applied to Al 0.83 In 0.17 N and Al 0.3 Ga 0.7 N barrier heterostructures. As expected, the electrical properties of an Al 0.83 In 0.17 N barrier HEMT structure showed less stability than that of an Al 0.3 Ga 0.7 N barrier HEMT to the thermal annealing. The structural properties of Al 0.83 In 0.17 N/GaN also showed more evidence for decomposition than that of the Al 0.3 Ga 0.7 N/GaN structure after 800 °C post-annealing

  12. Analysis of the influence of synthetic paramaters on the structure and physico-chemical properties of non-spherical iron oxide nanocrystals and their biological stability and compatibility.

    Science.gov (United States)

    Pardo, Alberto; Pujales, Rosa; Blanco, Mateo; Villar-Alvarez, Eva M; Barbosa, Silvia; Taboada, Pablo; Mosquera, Víctor

    2016-01-14

    In this work, we analyzed the effects of subtle changes in the synthetic conditions and synthetic parameters on the resulting size, shape, monodispersity, crystallinity and magnetic properties of iron oxide nanocrystals (IONCs) obtained through a modified one pot method for the production of mainly cubic-shaped nanoparticles (NPs). Cubic, octahedral and cuboctahedral shapes with different sizes and monodispersity could be obtained by slightly changing the stabilizer/precursor molar ratio, the precursor concentration, the reaction time and temperature and/or the heating rate. Their physical properties were evaluated using high-resolution transmission electron microscopy (HRTEM), X-ray powder diffraction (XRD), selected-area electron diffraction (SAED) and a superconducting quantum interference (SQUID) device. It was found that monodisperse cubic nanocrystals from ca. 25 to 94 nm could be obtained either by changing the precursor concentration, the heating rate or the reaction time. These cubic nanocrystals were ferrimagnetic in the whole temperature rage analyzed, with saturation magnetization values even larger than those of bulk magnetite. In addition, slightly truncated octahedral NPs could be achieved at relatively large heating ramp rates, whereas cubooctahedral NPs were derived by simply increasing the stabilizer/precursor molar ratio. The saturation magnetization of both types of NPs was slightly lower than the cubic ones, but they were still ferrimagnetic in the whole temperature range analyzed. Moreover, transfer to aqueous solution was possible by a ligand exchange with dimercaptosuccinic acid (DMSA) providing, at the same time, chemical groups for additional functionalization if required. The DMSA-coated cubic IONCs were fairly stable in culture medium, allowing their internalization by different cell types. The NPs inside the cells were located in the cytoplasm and most of them showed a perinuclear distribution. Moreover, a great cytocompatibility in a

  13. Heat treatment and gamma radiation effects on the physical-chemical, microbiological and sensory stability of pure sugarcane juice or added with fruit juices, stored under refrigeration

    International Nuclear Information System (INIS)

    Oliveira, Aline Cristine Garcia de

    2007-01-01

    Sugarcane juice is a taste drink, energetic, no alcoholic that conserves all the nutrients in cane sugar. It was very appreciated by the Brazilian population and its production has been shown to be a highly lucrative business. This research had the following objectives: evaluate the acceptance of the consuming market and the stability of pure sugarcane juice or added with natural fruit juices, submitted of heat treatment (70 deg C/ 25 min) and/ or gamma radiation (2,5 kGy) and stored in high density polyethylene bottles, under refrigeration (5 +- 1 deg C). Sugarcane juice market test was evaluated through the application of 350 questionnaires on six Sao Paulo cities. Sugarcane juice stability was evaluated through microbiological (psychotropic count, lactic bacteria and yeasts and molds count), physical-chemical (pH, color, titratable acidity, soluble solids, ratio and polyphenoloxidase activity) and sensory (hedonic test) parameters. Centesimal composition was determined analyzing: humidity, caloric value, total carbohydrates, total and reducing sugars, lipids, proteins, ascorbic acid, ash and minerals. Sugarcane juice shelf life period was determinate ever 7 days over a period of 42 days stored under refrigeration. The data were submitted to the variance analysis and compared by Tukey's test (p<0,05). Among the 350 interviewed people, more of the half one is interested about its habitual food safe and care about street foods. Sandwiches had been cited foods as routinely consumed, followed for the sugarcane juice and 'pastel'. Among the interviewed ones, 80% had mentioned to appreciate sugarcane juice. It had not correlation between age and school age and the preference for the consumption form was with lemon juice addition. About 55% of the interviewed ones had mentioned that would more frequently consume sugarcane juice processed and packed. Sugarcane juice processing did not modify the flavor and taste of the drink. It was concluded from the sensory analyses

  14. Characterization of Wood-Plastic Composites Made with Different Lignocellulosic Materials that Vary in Their Morphology, Chemical Composition and Thermal Stability

    Directory of Open Access Journals (Sweden)

    Ke-Chang Hung

    2017-12-01

    Full Text Available In this study, four kinds of lignocellulosic fibers (LFs, namely, those from Chinese fir (Cunninghamia lanceolata, Taiwan red pine (Pinus taiwanensis, India-charcoal trema (Trema orientalis and makino bamboo (Phyllostachys makinoi, were selected as reinforcements and incorporated into high-density polyethylene (HDPE to manufacture wood-plastic composites (WPCs by a flat platen pressing process. In addition to comparing the differences in the physico-mechanical properties of these composites, their chemical compositions were evaluated and their thermal decomposition kinetics were analyzed to investigate the effects of the lignocellulosic species on the properties of the WPCs. The results showed that the WPC made with Chinese fir displayed a typical M-shaped vertical density profile due to the high aspect ratio of its LFs, while a flat vertical density profile was observed for the WPCs made with other LFs. Thus, the WPC made with Chinese fir exhibited higher flexural properties and lower internal bond strength (IB than other WPCs. In addition, the Taiwan red pine contained the lowest holocellulose content and the highest extractives and α-cellulose contents, which gave the resulting WPC lower water absorption and flexural properties. On the other hand, consistent with the flexural properties, the results of thermal decomposition kinetic analysis showed that the activation energy of the LFs at 10% of the conversion rate increased in the order of Taiwan red pine (146–161 kJ/mol, makino bamboo (158–175 kJ/mol, India-charcoal trema (185–194 kJ/mol and Chinese fir (194–202 kJ/mol. These results indicate that the morphology, chemical composition and thermal stability of the LFs can have a substantial impact on the physico-mechanical properties of the resulting WPCs.

  15. Physico-chemical Stability of MabThera Drug-product Solution for Subcutaneous Injection under in-use Conditions with Different Administration Materials.

    Science.gov (United States)

    Mueller, Claudia; Dietel, Elke; Heynen, Severin R; Nalenz, Heiko; Goldbach, Pierre; Mahler, Hanns-Christian; Schmidt, Johannes; Grauschopf, Ulla; Schoenhamnmer, Karin

    2015-01-01

    MabThera is an essential component of the standard-of-care regimens in the treatment of non-Hodgkin lymphoma and Chronic Lymphatic Leukemia. MabThera for subcutaneous injection is a novel line extension that has been approved by the European Medicines Agency for the treatment of patients with follicular lymphoma and diffuse large B-cell lymphoma. This study aimed to evaluate in-use stability data of MabThera subcutaneous drug-product solution in single-use syringes for subcutaneous administration according to the European Medicines Agency guideline. The drug-product solution was exposed to material contact surfaces of five different administration setups commonly used in subcutaneous drug delivery. MabThera subcutaneous was transferred under aseptic conditions into polypropylene and polycarbonate syringes and stored for 1, 2, and 4 weeks at 2°C to 8°C followed by 24 hours at 30°C. After storage, subcutaneous administration was simulated and MabThera subcutaneous drug-product solution quality attributes were evaluated by using compendial physico-chemical tests, as well as suitable and validated molecule- and formulation-specific analytical methods. MabThera subcutaneous vials were treated and analyzed in parallel. The physico-chemical results of MabThera subcutaneous in the different setups were comparable to the control for all timepoints. No change in drug-product quality after storage and simulated administration was found compared to the control. However, since single-dose products do not contain preservatives, microbial contamination and growth needs to be avoided and product sterility needs to be ensured. The results showed that MabThera subcutaneous remains compatible and stable, from a physico-chemical perspective, for up to 4 weeks at 2°C to 8°C followed by 24 hours at 30°C with the contact materials tested in this study. In order to avoid and minimize microbial growth, MabThera subcutaneous should be used immediately after removal from the original

  16. A comprehensive overview on the micro- and nano-technological encapsulation advances for enhancing the chemical stability and bioavailability of carotenoids.

    Science.gov (United States)

    Soukoulis, Christos; Bohn, Torsten

    2018-01-02

    Carotenoids are lipophilic secondary plant compounds, and their consumption within fruits and vegetables has been positively correlated with a decreased risk of developing several chronic diseases. However, their bioavailability is often compromised due to incomplete release from the food matrix, poor solubility and potential degradation during digestion. In addition, carotenoids in food products are prone to oxidative degradation, not only lowering the nutritional value of the product but also triggering other quality deteriorative changes, such as formation of lipid pro-oxidants (free radicals), development of discolorations or off-flavor defects. Encapsulation refers to a physicochemical process, aiming to entrap an active substance in structurally engineered micro- or nano-systems, in order to develop an effective thermodynamical and physical barrier against deteriorative environmental conditions, such as water vapor, oxygen, light, enzymes or pH. In this context, encapsulation of carotenoids has shown to be a very effective strategy to improve their chemical stability under common processing conditions including storage. In addition, encapsulation may also enhance bioavailability (via influencing bioaccessibility and absorption) of lipophilic bioactives, via modulating their release kinetics from the carrier system, solubility and interfacial properties. In the present paper, it is aimed to present the state of the art of carotenoid microencapsulation in order to enhance storability and bioavailability alike.

  17. Quantum Dot Photovoltaics in the Extreme Quantum Confinement Regime: The Surface-Chemical Origins of Exceptional Air- and Light-Stability

    KAUST Repository

    Tang, Jiang

    2010-02-23

    We report colloidal quantum dot (CQDs) photovoltaics having a ∼930 nm bandgap. The devices exhibit AM1.5G power conversion efficiencies in excess of 2%. Remarkably, the devices are stable in air under many tens of hours of solar illumination without the need for encapsulation. We explore herein the origins of this ordersof-magnitude improvement in air stability compared to larger PbS dots. We find that small and large dots form dramatically different oxidation products, with small dots forming lead sulfite primarily and large dots, lead sulfate. The lead sulfite produced on small dots results in shallow electron traps that are compatible with excellent device performance; whereas the sulfates formed on large dots lead to deep traps, midgap recombination, and consequent catastrophic loss of performance. We propose and offer evidence in support of an explanation based on the high rate of oxidation of sulfur-rich surfaces preponderant in highly faceted large-diameter PbS colloidal quantum dots. © 2010 American Chemical Society.

  18. Radiation and chemical stability of 2-deoxy-2-[18F]fluoro-D-glucose radiopharmaceutical. Author-review of thesis

    International Nuclear Information System (INIS)

    Buriova, M.

    2004-07-01

    free [ 18 F]fluoride and autoradiolysis products should not influence the tomographic imaging. This thesis is the first attempt of a complex quantification of chemical and radiation-chemical stability of physiological solutions of 2-[ 18 F]FDG. It appeared that the 2-[ 18 F]FDG is the radiopharmaceutical of high radiation and chemical stability. The thesis also illustrates possibilities of LC/MS/RAD system not only in routine quality control of radiopharmaceuticals but also in research of the new ones

  19. [Autoerotic fatalities in Greater Dusseldorf].

    Science.gov (United States)

    Hartung, Benno; Hellen, Florence; Borchard, Nora; Huckenbeck, Wolfgang

    2011-01-01

    Autoerotic fatalities in the Greater Dusseldorf area correspond to the relevant medicolegal literature. Our results included exclusively young to middle-aged, usually single men who were found dead in their city apartments. Clothing and devices used showed a great variety. Women's or fetish clothing and complex shackling or hanging devices were disproportionately frequent. In most cases, death occurred due to hanging or ligature strangulation. There was no increased incidence of underlying psychiatric disorders. In most of the deceased no or at least no remarkable alcohol intoxication was found. Occasionally, it may be difficult to reliably differentiate autoerotic accidents, accidents occurring in connection with practices of bondage & discipline, dominance & submission (BDSM) from natural death, suicide or homicide.

  20. Planning for greater confinement disposal

    International Nuclear Information System (INIS)

    Gilbert, T.L.; Luner, C.; Meshkov, N.K.; Trevorrow, L.E.; Yu, C.

    1985-01-01

    A report that provides guidance for planning for greater-confinement disposal (GCD) of low-level radioactive waste is being prepared. The report addresses procedures for selecting a GCD technology and provides information for implementing these procedures. The focus is on GCD; planning aspects common to GCD and shallow-land burial are covered by reference. Planning procedure topics covered include regulatory requirements, waste characterization, benefit-cost-risk assessment and pathway analysis methodologies, determination of need, waste-acceptance criteria, performance objectives, and comparative assessment of attributes that support these objectives. The major technologies covered include augered shafts, deep trenches, engineered structures, hydrofracture, improved waste forms, and high-integrity containers. Descriptive information is provided, and attributes that are relevant for risk assessment and operational requirements are given. 10 refs., 3 figs., 2 tabs

  1. Chemical and Radiochemical Composition of Thermally Stabilized Plutonium Oxide from the Plutonium Finishing Plant Considered as Alternate Feedstock for the Mixed Oxide Fuel Fabrication Facility

    International Nuclear Information System (INIS)

    Tingey, Joel M.; Jones, Susan A.

    2005-01-01

    Eighteen plutonium oxide samples originating from the Plutonium Finishing Plant (PFP) on the Hanford Site were analyzed to provide additional data on the suitability of PFP thermally stabilized plutonium oxides and Rocky Flats oxides as alternate feedstock to the Mixed Oxide Fuel Fabrication Facility (MFFF). Radiochemical and chemical analyses were performed on fusions, acid leaches, and water leaches of these 18 samples. The results from these destructive analyses were compared with nondestructive analyses (NDA) performed at PFP and the acceptance criteria for the alternate feedstock. The plutonium oxide materials considered as alternate feedstock at Hanford originated from several different sources including Rocky Flats oxide, scrap from the Remote Mechanical C-Line (RMC) and the Plutonium Reclamation Facility (PRF), and materials from other plutonium conversion processes at Hanford. These materials were received at PFP as metals, oxides, and solutions. All of the material considered as alternate feedstock was converted to PuO2 and thermally stabilized by heating the PuO2 powder at 950 C in an oxidizing environment. The two samples from solutions were converted to PuO2 by precipitation with Mg(OH)2. The 18 plutonium oxide samples were grouped into four categories based on their origin. The Rocky Flats oxide was divided into two categories, low- and high-chloride Rocky Flats oxides. The other two categories were PRF/RMC scrap oxides, which included scrap from both process lines and oxides produced from solutions. The two solution samples came from samples that were being tested at Pacific Northwest National Laboratory because all of the plutonium oxide from solutions at PFP had already been processed and placed in 3013 containers. These samples originated at the PFP and are from plutonium nitrate product and double-pass filtrate solutions after they had been thermally stabilized. The other 16 samples originated from thermal stabilization batches before canning at

  2. Greater confinement disposal of radioactive wastes

    International Nuclear Information System (INIS)

    Trevorrow, L.E.; Gilbert, T.L.; Luner, C.; Merry-Libby, P.A.; Meshkov, N.K.; Yu, C.

    1985-01-01

    Low-level radioactive waste (LLW) includes a broad spectrum of different radionuclide concentrations, half-lives, and hazards. Standard shallow-land burial practice can provide adequate protection of public health and safety for most LLW. A small volume fraction (approx. 1%) containing most of the activity inventory (approx. 90%) requires specific measures known as greater-confinement disposal (GCD). Different site characteristics and different waste characteristics - such as high radionuclide concentrations, long radionuclide half-lives, high radionuclide mobility, and physical or chemical characteristics that present exceptional hazards - lead to different GCD facility design requirements. Facility design alternatives considered for GCD include the augered shaft, deep trench, engineered structure, hydrofracture, improved waste form, and high-integrity container. Selection of an appropriate design must also consider the interplay between basic risk limits for protection of public health and safety, performance characteristics and objectives, costs, waste-acceptance criteria, waste characteristics, and site characteristics

  3. Theoretical study of stability and reaction mechanism of CuO supported on ZrO{sub 2} during chemical looping combustion

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Minjun; Liu, Jing, E-mail: liujing27@mail.hust.edu.cn; Shen, Fenghua; Cheng, Hao; Dai, Jinxin; Long, Yan

    2016-03-30

    Graphical abstract: - Highlights: • The stability and reaction mechanism of CuO supported on ZrO{sub 2} were studied by DFT. • ZrO{sub 2} provides a high resistance to CuO sintering. • ZrO{sub 2} promotes the activity of CuO for CO oxidation in fuel reactor. • The energy barriers are low enough for CuO/ZrO{sub 2} oxidation reaction in air reactor. - Abstract: The addition of inert support is important for the Cu-based oxygen carrier used in chemical looping combustion (CLC). The effects of the ZrO{sub 2} support on the stability and reactivity of Cu-based oxygen carrier were investigated using the density functional theory (DFT). First, the sintering inhibition mechanism of ZrO{sub 2} that support active CuO was investigated. The optimized Cu{sub 4}O{sub 4}/ZrO{sub 2} structure showed a strong interaction occurred between the Cu{sub 4}O{sub 4} cluster and ZrO{sub 2}(1 0 1) surface. The interaction prevented the migration and agglomeration of CuO. Next, the adsorption of CO on Cu{sub 4}O{sub 4}/ZrO{sub 2} and the mechanism of the CuO/ZrO{sub 2} reduction by CO were studied. CO mainly chemisorbed on the Cu site and ZrO{sub 2} acted as an electron donor in the adsorption system. The energy barrier of CuO/ZrO{sub 2} reduction by CO (0.79 eV) was much lower than that of the pure CuO cluster (1.44 eV), indicating that ZrO{sub 2} had a positive effect on CuO/ZrO{sub 2} reduction by CO. After CO was oxidized in the fuel reactor, the CuO was reduced into Cu. The adsorption of O{sub 2} on Cu{sub 2}/ZrO{sub 2} and the most likely pathway of Cu{sub 2}/ZrO{sub 2} oxidation by O{sub 2} were investigated. The adsorption of O{sub 2} was found a strong chemisorption behavior. The energy barriers were low enough for the Cu-based oxygen carrier oxidation reaction.

  4. Thermal stability of an InAlN/GaN heterostructure grown on silicon by metal-organic chemical vapor deposition

    Energy Technology Data Exchange (ETDEWEB)

    Watanabe, Arata, E-mail: a.watanabe.106@nitech.jp; Freedsman, Joseph J.; Urayama, Yuya; Christy, Dennis [Research Center for Nano Devices and Advanced Materials, Nagoya Institute of Technology, Gokiso-cho, Showa-ku, Nagoya 466 8555 (Japan); Egawa, Takashi, E-mail: egawa.takashi@nitech.ac.jp [Research Center for Nano Devices and Advanced Materials, Nagoya Institute of Technology, Gokiso-cho, Showa-ku, Nagoya 466 8555 (Japan); Innovation Center for Multi-Business of Nitride Semiconductors, Nagoya Institute of Technology, Gokiso-cho, Showa-ku, Nagoya 466 8555 (Japan)

    2015-12-21

    The thermal stabilities of metal-organic chemical vapor deposition-grown lattice-matched InAlN/GaN/Si heterostructures have been reported by using slower and faster growth rates for the InAlN barrier layer in particular. The temperature-dependent surface and two-dimensional electron gas (2-DEG) properties of these heterostructures were investigated by means of atomic force microscopy, photoluminescence excitation spectroscopy, and electrical characterization. Even at the annealing temperature of 850 °C, the InAlN layer grown with a slower growth rate exhibited a smooth surface morphology that resulted in excellent 2-DEG properties for the InAlN/GaN heterostructure. As a result, maximum values for the drain current density (I{sub DS,max}) and transconductance (g{sub m,max}) of 1.5 A/mm and 346 mS/mm, respectively, were achieved for the high-electron-mobility transistor (HEMT) fabricated on this heterostructure. The InAlN layer grown with a faster growth rate, however, exhibited degradation of the surface morphology at an annealing temperature of 850 °C, which caused compositional in-homogeneities and impacted the 2-DEG properties of the InAlN/GaN heterostructure. Additionally, an HEMT fabricated on this heterostructure yielded lower I{sub DS,max} and g{sub m,max} values of 1 A/mm and 210 mS/mm, respectively.

  5. Greater Confinement Disposal trench and borehole operations status

    International Nuclear Information System (INIS)

    Harley, J.P. Jr.; Wilhite, E.L.; Jaegge, W.J.

    1987-01-01

    Greater Confinement Disposal (GCD) facilities have been constructed within the operating burial ground at the Savannah River Plant (SRP) to dispose of the higher activity fraction of SRP low-level waste. GCD practices of waste segregation, packaging, emplacement below the root zone, and waste stabilization are being used in the demonstration. 2 refs., 2 figs., 2 tabs

  6. Stress-induced NQO1 controls stability of C/EBPα against 20S proteasomal degradation to regulate p63 expression with implications in protection against chemical-induced skin cancer.

    Science.gov (United States)

    Patrick, B A; Jaiswal, A K

    2012-10-04

    Previously, we have shown a role of cytosolic NAD(P)H:quinone oxidoreductase 1 (NQO1) in the stabilization of p63 against 20S proteasomal degradation resulting in thinning of the epithelium and chemical-induced skin cancer (Oncogene (2011) 30, 1098-1107). Current studies have demonstrated that NQO1 control of CCAAT-enhancer binding protein (C/EBPα) against 20S proteasomal degradation also contributes to the upregulation of p63 expression and protection. Western and immunohistochemistry analysis revealed that disruption of the NQO1 gene in mice and mouse keratinocytes led to degradation of C/EBPα and loss of p63 gene expression. p63 promoter mutagenesis, transfection and chromatin immunoprecipitation assays identified a C/EBPα-binding site between nucleotide position -185 and -174 that bound to C/EBPα and upregulated p63 gene expression. Co-immunoprecipitation and immunoblot analysis demonstrated that 20S proteasomes directly interacted and degraded C/EBPα. NQO1 direct interaction with C/EBPα led to stabilization of C/EBPα against 20S proteasomal degradation. NQO1 protection of C/EBPα required binding of NADH with NQO1. Exposure of skin and keratinocytes to the chemical stress agent benzo(a)pyrene led to induction of NQO1 and stabilization of C/EBPα protein, resulting in an increase in p63 RNA and protein in wild-type but not in NQO1-/- mice. Collectively, the current data combined with previous data suggest that stress induction of NQO1 through both stabilization of C/EBPα and increase in p63 and direct stabilization of p63 controls keratinocyte differentiation, leading to protection against chemical-induced skin carcinogenesis. The studies are significant as 2-4% human individuals are homozygous and 23% are heterozygous for the NQO1P187S mutation and might be susceptible to stress-induced skin diseases.

  7. Plutonium inventories for stabilization and stabilized materials

    Energy Technology Data Exchange (ETDEWEB)

    Williams, A.K.

    1996-05-01

    The objective of the breakout session was to identify characteristics of materials containing plutonium, the need to stabilize these materials for storage, and plans to accomplish the stabilization activities. All current stabilization activities are driven by the Defense Nuclear Facilities Safety Board Recommendation 94-1 (May 26, 1994) and by the recently completed Plutonium ES&H Vulnerability Assessment (DOE-EH-0415). The Implementation Plan for accomplishing stabilization of plutonium-bearing residues in response to the Recommendation and the Assessment was published by DOE on February 28, 1995. This Implementation Plan (IP) commits to stabilizing problem materials within 3 years, and stabilizing all other materials within 8 years. The IP identifies approximately 20 metric tons of plutonium requiring stabilization and/or repackaging. A further breakdown shows this material to consist of 8.5 metric tons of plutonium metal and alloys, 5.5 metric tons of plutonium as oxide, and 6 metric tons of plutonium as residues. Stabilization of the metal and oxide categories containing greater than 50 weight percent plutonium is covered by DOE Standard {open_quotes}Criteria for Safe Storage of Plutonium Metals and Oxides{close_quotes} December, 1994 (DOE-STD-3013-94). This standard establishes criteria for safe storage of stabilized plutonium metals and oxides for up to 50 years. Each of the DOE sites and contractors with large plutonium inventories has either started or is preparing to start stabilization activities to meet these criteria.

  8. Accelerated testing for studying pavement design and performance (FY 2003) : evaluation of the chemical stabilized subgrade soil (CISL Experiment No. 12).

    Science.gov (United States)

    2008-01-01

    The Midwest States Accelerated Pavement Testing Pooled Fund Program, financed by the highway departments : of Missouri, Iowa, Kansas and Nebraska, has supported an accelerated pavement testing (APT) project to compare : the performance of stabilized ...

  9. Improving the stability of coal slurries: Quarterly progress report for the period March 15, 1987-June 15, 1987

    Energy Technology Data Exchange (ETDEWEB)

    Fogler, H.S.

    1987-01-01

    Gum tragacanth, GT has been found to stabilize colloidal solutions. The stabilization effect with GT depends significantly on the pore size of the filter membrane. To investigate the dependence of the stabilization effect on the pore size of filter membrane, the Fourier transform infrared spectroscopy, FT-IR was employed. The FT-IR spectra showed that the chemical structure of GT was identical before and after the filtration. Next, the gel permeation chromatography was carried out, and it was found that the molecular weight distribution changes due to the filtration. Therefore, in order to study the effect of molecular weight on the stabilization effect, the amount of GT adsorbed, the zeta potential and steric layer thickness were measured. The results showed that the greater stabilization effect for the GT having the greater proportion of higher molecular weight fraction can be attributed to the greater steric layer thickness. 5 refs., 6 figs., 1 tab.

  10. Oxygen nonstoichiometry and thermo-chemical stability of La0.6Sr0.4CoO3−δ

    International Nuclear Information System (INIS)

    Kuhn, M.; Hashimoto, S.; Sato, K.; Yashiro, K.; Mizusaki, J.

    2013-01-01

    The oxygen nonstoichiometry of La 0.6 Sr 0.4 CoO 3−δ has been the topic of various reports in the literature, but has been exclusively measured at high oxygen partial pressures, pO 2 , and/or elevated temperatures. For applications of La 0.6 Sr 0.4 CoO 3−δ , such as solid oxide fuel cell cathodes or oxygen permeation membranes, knowledge of the oxygen nonstoichiometry and thermo-chemical stability over a wide range of pO 2 is crucial, as localized low pO 2 could trigger failure of the material and device. By employing coulometric titration combined with thermogravimetry, the oxygen nonstoichiometry of La 0.6 Sr 0.4 CoO 3−δ was measured at high and intermediate pO 2 until the material decomposed (at log(pO 2 /bar)≈−4.5 at 1073 K). For a gradually reduced sample, an offset in oxygen content suggests that La 0.6 Sr 0.4 CoO 3−δ forms a “super-reduced” solid solution before decomposing. When the sample underwent alternate reduction–oxidation, a hysteresis-like pO 2 dependence of the oxygen content in the decomposition pO 2 range was attributed to the reversible formation of ABO 3 and A 2 BO 4 phases. Reduction enthalpy and entropy were determined for the single-phase region and confirmed interpolated values from the literature. - Graphical abstract: Oxygen nonstoichiometry (shown as 3−δ) of La 0.6 Sr 0.4 CoO 3−δ as a function of pO 2 at 773–1173 K. The experimental data were obtained by thermogravimetric analysis (TG) and coulometric titration (measured either by a simple reduction (CT1) or a “two-step-forward one-step-back” reduction–oxidation (CT2) procedure). D1 and D2 denote the decomposition pO 2 . The solid lines are the fit to the thermogravimetry and CT1 data. The dashed lines represent the non-equilibrium region where the sample shows a super-reduced state. Highlights: ► Oxygen nonstoichiometry of La 0.6 Sr 0.4 CoO 3−δ at intermediate temperatures and p(O2). ► Experimental confirmation of previously interpolated

  11. V.I. Vernadskiy study of biochemical cycles and role of biocenoses trophic structure in their stabilization under background conditions and at chemical pollution

    International Nuclear Information System (INIS)

    Bezel, V.S.; Bel'skij, E.A.; Bel'skaya, E.A.; Zhujkova, T.V.; Mukhacheva, S.V.; Nesterkov, A.V.

    2008-01-01

    In the present report the participation of different trophic belonging organisms in biogeochemical cycles at the pollution of the environment by aerogenic emissions of metallurgical enterprises are discussed. Investigation in and around southern taiga of Middle Ural in liable to heavy metals contamination areas was made. Several areas with different level of soil contamination from background uncontaminated (at a distance 20-30 km from emission source) to buffer (4-7 km) and impact (1-2 km) were separated out. Mechanism of chemical elements accumulation by different components of terrestrial ecosystems that the aggregate of trophic levels present: depository environment (soil), producers (plants), consumers of several levels (phytophages, zoophages) was studied. Accumulation of chemical elements was considered in biomass of trophic levels both with content of chemical elements in the soil on a regional background level and by their intensive contamination. The findings enable to evaluate the quantity of chemical elements involved in biogenic cycles by different trophic belonging organisms

  12. Chemical stabilization and high pressure synthesis of Ba-free Hg-based superconductors, (Hg,M)Sr{sub 2}Ca{sub n-1}Cu{sub n}O{sub y}(N=1{approximately}3)

    Energy Technology Data Exchange (ETDEWEB)

    Kishio, K. [Univ. of Tokyo (Japan)]|[Kyoto Univ. (Japan); Shimoyama, J.; Hahakura, S. [Univ. of Tokyo (Japan)] [and others

    1994-12-31

    A homologous series of new Hg-based HTSC compounds, (Hg,M)Sr{sub 2}Ca{sub n-1}Cu{sub n}O{sub y} with n=1 to 3, have been synthesized. The stabilization of the pure phases have been accomplished by chemical doping of third elements such as M=Cr, Mo and Re. While the Hg1201(n=1) phase was readily obtained in this way, it was necessary to simultaneously dope Y into the Ca site to stabilize the Hg1212(n=2) phase. On the other hand, single-phase Y-free Hg1212(n=2) and Hg1223(n=3) samples were synthesized only under a high pressure of 6 GPa. In sharp contrast to the Ba-containing compounds, all the samples prepared in the present study have been quite stable during the synthesis and no deterioration in air has been observed after the preparation.

  13. Study of chemical stability of lemon oil components in sodium caseinate-lactose glycoconjugate-stabilized oil-in-water emulsions using solid-phase microextraction-gas chromatography.

    Science.gov (United States)

    Sabik, Hassan; Achouri, Allaoua; Alfaro, Maria; Pelletier, Marylène; Belanger, Denis; Britten, Michel; Fustier, Patrick

    2014-07-25

    A headspace solid-phase microextraction (HS-SPME) combined with gas chromatography-mass spectrometry (GC/MS) method was developed to quantify lemon oil components and their degradation products in oil-in-water (O/W) emulsions prepared with sodium caseinate-heated-lactose (NaC-T + Lact) glycoconjugates as wall materials at two pH values (3.0 and 6.8). NaC-T + Lact conjugates had a significantly lower solubility at both pHs. Hydrolysis prior to glycation enhanced the solubility of glycoconjugates. Glycation with lactose did not improve the emulsion activity of NaC, while caseinate glycoconjugates showed much stronger antioxidant activity than the NaC-control sample. This might be due to the presence of melanoidins formed between the sugar and amino acid compounds as supported by the increase in browning intensity. Among the SPME-fibres tested, carboxen/polydimethylsiloxane (CAR/PDMS) provided better results in terms of sensitivity and selectivity for oil lemon components and their degradation products. Storage studies of these emulsions demonstrated that glycated NaC-T + Lact showed protection against peroxidation compared to the control. However, acidic pH conditions altered their stability over storage time. The major off-flavor components (α-terpineol and carvone) were inhibited in emulsions stabilized with glycated NaC, particularly at pH 6.8. The use of NaC-T + Lact conjugates showed improved encapsulation efficiency and stability and could be used as potential food ingredient-emulsifiers for stabilising citrus oils against oxidative degradation in food and beverage applications.

  14. Stabilization of heavy metals in Tehran agricultural land

    International Nuclear Information System (INIS)

    Torabian, A.; Sadeghi, Sh.

    2001-01-01

    In order to prevent contamination of heavy metals accumulation in soil, plant, and ground water, several methods of prevention are studied, and tested worldwide. One of the method which has not been studied and applied in Iran is stabilization of heavy metals in soil by using clay minerals. Clay minerals due to hydration properties can adsorb organic and inorganic substances. Two clay minerals were used in this research: Bentonite with chemical structure of 2 to 1 (Two layers of silica and one layer of Aluminium) with CEC equal to 85 m eq/100 grams and Kao line with chemical structure of one to one (one layer silica and one layer Aluminum) and CEC=3 m eq/100 grams of soil. The physical and chemical properties of these two kinds of clays were different. Stabilization of heavy metals with different percentages of these two clays (7%, 15%, 22%) with different p H (4,7,8,11.5) were studied. The results indicate that with increasing of stabilizing agent at p H=7.8 and greater, stabilization of heavy metals increased significantly. The results also indicate the stabilization of heavy metals decreased rapidly at p H 4 and lower. The results of this study agree with the work of pervious researchers

  15. Characterisation, phase stability and surface chemical properties of photocatalytic active Zr and y co-doped anatase TiO2 nanoparticles

    Czech Academy of Sciences Publication Activity Database

    Mattsson, A.; Lejon, C.; Bakardjieva, Snejana; Štengl, Václav; Österlund, L.

    2013-01-01

    Roč. 199, March (2013), s. 212-223 ISSN 0022-4596 R&D Projects: GA MPO FI-IM5/231 Institutional support: RVO:61388980 Keywords : Catalytic properties * Chemical synthesis * Nanostructures * Phase transactions Subject RIV: CA - Inorganic Chemistry Impact factor: 2.200, year: 2013

  16. Improved chemical stability and cyclability in Li2S–P2S5–P2O5–ZnO composite electrolytes for all-solid-state rechargeable lithium batteries

    International Nuclear Information System (INIS)

    Hayashi, Akitoshi; Muramatsu, Hiromasa; Ohtomo, Takamasa; Hama, Sigenori; Tatsumisago, Masahiro

    2014-01-01

    Highlights: • Chemical stability in air of Li 2 S–P 2 S 5 –P 2 O 5 –ZnO composite electrolytes was examined. • A partial substitution of P 2 O 5 for P 2 S 5 decreased the rate of H 2 S generation. • The addition of ZnO to the glasses reduced the amount of H 2 S. • All-solid-state lithium cells using the developed composite electrolytes exhibited good cyclability. -- Abstract: Sulfide glasses with high Li + ion conductivity are promising solid electrolytes for all-solid-state rechargeable lithium batteries. This study specifically examined the chemical stability of Li 2 S–P 2 S 5 -based glass electrolytes in air. Partial substitution of P 2 O 5 for P 2 S 5 decreased the rate of H 2 S generation from glass exposed to air. The addition of ZnO to the Li 2 S–P 2 S 5 –P 2 O 5 glasses as a H 2 S absorbent reduced the H 2 S gas release. A composite electrolyte prepared from 90 mol% of 75Li 2 S⋅21P 2 S 5 ⋅4P 2 O 5 (mol%) glass and 10 mol% ZnO was applied to all-solid-state cells. The all-solid-state In/LiCoO 2 cell with the composite electrolyte showed good cyclability as a lithium secondary battery

  17. Surface-stabilized gold nanocatalysts

    Science.gov (United States)

    Dai, Sheng [Knoxville, TN; Yan, Wenfu [Oak Ridge, TN

    2009-12-08

    A surface-stabilized gold nanocatalyst includes a solid support having stabilizing surfaces for supporting gold nanoparticles, and a plurality of gold nanoparticles having an average particle size of less than 8 nm disposed on the stabilizing surfaces. The surface-stabilized gold nanocatalyst provides enhanced stability, such as at high temperature under oxygen containing environments. In one embodiment, the solid support is a multi-layer support comprising at least a first layer having a second layer providing the stabilizing surfaces disposed thereon, the first and second layer being chemically distinct.

  18. Greater trochanteric pain syndrome diagnosis and treatment.

    Science.gov (United States)

    Mallow, Michael; Nazarian, Levon N

    2014-05-01

    Lateral hip pain, or greater trochanteric pain syndrome, is a commonly seen condition; in this article, the relevant anatomy, epidemiology, and evaluation strategies of greater trochanteric pain syndrome are reviewed. Specific attention is focused on imaging of this syndrome and treatment techniques, including ultrasound-guided interventions. Copyright © 2014 Elsevier Inc. All rights reserved.

  19. Improving greater trochanteric reattachment with a novel cable plate system.

    Science.gov (United States)

    Baril, Yannick; Bourgeois, Yan; Brailovski, Vladimir; Duke, Kajsa; Laflamme, G Yves; Petit, Yvan

    2013-03-01

    Cable-grip systems are commonly used for greater trochanteric reattachment because they have provided the best fixation performance to date, even though they have a rather high complication rate. A novel reattachment system is proposed with the aim of improving fixation stability. It consists of a Y-shaped fixation plate combined with locking screws and superelastic cables to reduce cable loosening and limit greater trochanter movement. The novel system is compared with a commercially available reattachment system in terms of greater trochanter movement and cable tensions under different greater trochanteric abductor application angles. A factorial design of experiments was used including four independent variables: plate system, cable type, abductor application angle, and femur model. The test procedure included 50 cycles of simultaneous application of an abductor force on the greater trochanter and a hip force on the femoral head. The novel plate reduces the movements of a greater trochanter fragment within a single loading cycle up to 26%. Permanent degradation of the fixation (accumulated movement based on 50-cycle testing) is reduced up to 46%. The use of superelastic cables reduces tension loosening up to 24%. However this last improvement did not result in a significant reduction of the grater trochanter movement. The novel plate and cables present advantages over the commercially available greater trochanter reattachment system. The plate reduces movements generated by the hip abductor. The superelastic cables reduce cable loosening during cycling. Both of these positive effects could decrease the risks related to grater trochanter non-union. Copyright © 2012 IPEM. Published by Elsevier Ltd. All rights reserved.

  20. RE-UTILIZATION OF INORGANIC SOLID WASTE (LIME MUD AS FOREST ROAD STABILIZER FROM THE CHEMICAL RECOVERY PROCESS IN KRAFT PULP MILL

    Directory of Open Access Journals (Sweden)

    Habip Eroğlu

    2005-04-01

    Full Text Available Waste handling is a concern in all pulp and paper mills. Best available techniques for reducing waste is to minimize the generation of solid waste and/or reuse these materials, wherever practicable. One of the most important solid wastes is lime mud which is generated from the kraft pulping in its chemical recovery process. This paper explores the composition of lime mud resulting from the chemical recovery unite of kraft pulp mill and investigation of this waste for re-using beneficially on sub grade and pavement of forest road as a alternative disposal method. Lime mud obtained from the re-causticising process in SEKA pulp mill that utilizes wheat straw and reed as the principal raw material was supplied with % 47 water content and its chemical and physical characterisations was performed according to standard methods. Dried waste to environmental condition was mixed with certain amount to composite cement for using on pavement and sandy clay, loamy clay and clay soils for enriching forest road sub grade properties. In order to investigate the lime mud addition on pavement and sub grade properties necessary physical tests were performed. As a consequence this study reveals that while waste of lime mud causes environmental and economical problem with conventional disposal techniques and/or abandoning to environment, this waste can be used as good stabilisation materials on forest road sub-grade and pavement without any environmental problem.

  1. A stability comparison of redox-active layers produced by chemical coupling of an osmium redox complex to pre-functionalized gold and carbon electrodes

    International Nuclear Information System (INIS)

    Boland, Susan; Foster, Kevin; Leech, Donal

    2009-01-01

    The production of stable redox active layers on electrode surfaces is a key factor for the development of practical electronic and electrochemical devices. Here, we report on a comparison of the stability of redox layers formed by covalently coupling an osmium redox complex to pre-functionalized gold and graphite electrode surfaces. Pre-treatment of gold and graphite electrodes to provide surface carboxylic acid groups is achieved via classical thiolate self-assembled monolayer formation on gold surfaces and the electro-reduction of an in situ generated aryldiazonium salt from 4-aminobenzoic acid on gold, glassy carbon and graphite surfaces. These surfaces have been characterized by AFM and electrochemical blocking studies. The surface carboxylate is then used to tether an osmium complex, [Os(2,2'-bipyridyl) 2 (4-aminomethylpyridine)Cl]PF 6 , to provide a covalently bound redox active layer, E 0 '' of 0.29 V (vs. Ag/AgCl in phosphate buffer, pH 7.4), on the pre-treated electrodes. The aryldiazonium salt-treated carbon-based surfaces showed the greatest stability, represented by a decrease of <5% in the peak current for the Os(II/III) redox transition of the immobilized complex over a 3-day period, compared to a decrease of 19% and 14% for the aryldiazonium salt treated and thiolate treated gold surfaces, respectively, over the same period

  2. Cable Stability

    Energy Technology Data Exchange (ETDEWEB)

    Bottura, L [European Organization for Nuclear Research, Geneva (Switzerland)

    2014-07-01

    Superconductor stability is at the core of the design of any successful cable and magnet application. This chapter reviews the initial understanding of the stability mechanism, and reviews matters of importance for stability such as the nature and magnitude of the perturbation spectrum and the cooling mechanisms. Various stability strategies are studied, providing criteria that depend on the desired design and operating conditions.

  3. Physico-chemical properties, oxidative stability and non-enzymatic browning in marine phospholipid emulsions and their use in food applications

    DEFF Research Database (Denmark)

    Lu, Henna Fung Sieng

    Marine phospholipids (PL) contain a high level of eicosapentaenoic acids (EPA) and docosahexaenoic acids (DHA), which have documented beneficial effect on human health. In addition, marine PL are more advantageous than crude or refined fish oils. Marine PL are more resistant to oxidation, provide...... of current marine PL that was used for emulsion preparation and food application. In addition, the oxidative stability and sensory quality of marine PL fortified products varied depending on the quality and source of marine PL used for fortification. Although the attempts to incorporate marine PL into food...... better bioavailability and ability to form liposomes. All these unique properties of marine PL make them an attractive choice as ingredients for food fortification. Nowadays, a wide range of food products fortified with n-3 triglycerides (TAG) are available worldwide. However, the feasibility of using...

  4. Effect of Cu2O morphology on photocatalytic hydrogen generation and chemical stability of TiO2/Cu2O composite.

    Science.gov (United States)

    Zhu, Lihong; Zhang, Junying; Chen, Ziyu; Liu, Kejia; Gao, Hong

    2013-07-01

    Improving photocatalytic activity and stability of TiO2/Cu2O composite is a challenge in generating hydrogen from water. In this paper, the TiO2 film/Cu2O microgrid composite was prepared via a microsphere lithography technique, which possesses a remarkable performance of producing H2 under UV-vis light irradiation, in comparison with pure TiO2 film, Cu2O film and TiO2 film/Cu2O film. More interesting is that in TiO2 film/Cu2O microgrid, photo-corrosion of Cu2O can be retarded. After deposition of Pt on its surface, the photocatalytic activity of TiO2/Cu2O microgrid in producing H2 is improved greatly.

  5. Greater nitrogen load in rivers and fjords

    International Nuclear Information System (INIS)

    Kaste, Oeyvind; Engen-Skaugen, Torill

    2005-01-01

    The article presents results from river and fjord climate simulations. Climatic changes may be amplified by hydrologic, water chemical and biologic systems. Connecting model systems, interpreting results and uncertainties are discussed

  6. Simultaneous bilateral isolated greater trochanter fracture

    Directory of Open Access Journals (Sweden)

    Maruti Kambali

    2013-01-01

    Full Text Available A 48-year-old woman sustained simultaneous isolated bilateral greater trochanteric fracture, following a road traffic accident. The patient presented to us 1 month after the injury. She presented with complaints of pain in the left hip and inability to walk. Roentgenograms revealed displaced comminuted bilateral greater trochanter fractures. The fracture of the left greater trochanter was reduced and fixed internally using the tension band wiring technique. The greater trochanter fracture on the right side was asymptomatic and was managed conservatively. The patient regained full range of motion and use of her hips after a postoperative follow-up of 6 months. Isolated fractures of the greater trochanter are unusual injuries. Because of their relative rarity and the unsettled controversy regarding their etiology and pathogenesis, several methods of treatment have been advocated. Furthermore, the reports of this particular type of injury are not plentiful and the average textbook coverage afforded to this entity is limited. In our study we discuss the mechanism of injury and the various treatment options available.

  7. Solid waste and chemical sludges: Stabilization/solidification processes and qualification of related products. Rifiuti solidi e fanghi: Processi di stabilizzazione/solidificazione e qualificazione dei prodotti ottenuti

    Energy Technology Data Exchange (ETDEWEB)

    Balzamo, S.; De Angelis, G. (ENEA, Casaccia (Italy). Area Energia Ambiente e Salute)

    A wide programme on cementation of radioactive and/or toxic wastes is being conducted at ENEA (Italian Agency for Energy, New Technologies and the Environment) laboratories. The main goal of the research work is to achieve solidified products which are reliable for transport and final disposal, as well as, to study possible reuse for civil purposes. Several characterization tests are made aiming at the optimization of process parameters and the verification of the quality of the final waste forms. Particular attention is being devoted to the problems related to the waste-matrix interaction, because no waste can be considered 'inert' from this point of view. It is therefore necessary to investigate the nature and the amount of such interactions through an accurate study of the chemical behaviour of the main waste components. That should allow researchers to get useful information to prevent the embedded wastes from causing deleterious effects to the solidification matrix.

  8. Protonation and structural/chemical stability of Ln{sub 2}NiO{sub 4+δ} ceramics vs. H{sub 2}O/CO{sub 2}: High temperature/water pressure ageing tests

    Energy Technology Data Exchange (ETDEWEB)

    Upasen, S. [Sorbonne Universités, UPMC Univ Paris 06, UMR 8233, MONARIS, 75005 Paris (France); CNRS-IP2CT, UMR 8233, MONARIS, F-75005 Paris (France); Batocchi, P.; Mauvy, F. [ICMCB, ICMCB-CNRS-IUT-Université de Bordeaux, 33608 Pessac Cedex (France); Slodczyk, A. [Sorbonne Universités, UPMC Univ Paris 06, UMR 8233, MONARIS, 75005 Paris (France); CNRS-IP2CT, UMR 8233, MONARIS, F-75005 Paris (France); Colomban, Ph., E-mail: philippe.colomban@upmc.fr [Sorbonne Universités, UPMC Univ Paris 06, UMR 8233, MONARIS, 75005 Paris (France); CNRS-IP2CT, UMR 8233, MONARIS, F-75005 Paris (France)

    2015-02-15

    Highlights: • High temperature/water pressure autoclave is used to study the reaction/corrosion at SOFC/HTSE electrode. • High stability of Pr{sub 2}NiO{sub 4+δ} (PNO) and Nd{sub 2}NiO{sub 4+δ} (NNO) dense ceramics vs. water pressure is demonstrated. • Protonated rare-earth nickelates retain the perovskite-type structure and their H-content is determined. • Very low laser illumination power is required to avoid RE nickelate phase transition. • Nickelates show increasing stability from La to Pr/Nd vs. CO{sub 2}-rich high temperature water vapor. - Abstract: Mixed ionic-electronic conductors (MIEC) such as rare-earth nickelates with a general formula Ln{sub 2}NiO{sub 4+δ} (Ln = La, Pr, Nd) appear as potential for energy production and storage systems: fuel cells, electrolysers and CO{sub 2} converters. Since a good electrode material should exhibit important stability in operating conditions, the structural and chemical stability of different nickelate-based, well-densified ceramics have been studied using various techniques: TGA, dilatometry, XRD, Raman scattering and IR spectroscopy. Consequently, La{sub 2}NiO{sub 4+δ} (LNO), Pr{sub 2}NiO{sub 4+δ} (PNO) and Nd{sub 2}NiO{sub 4+δ} (NNO) have been exposed during 5 days to high water vapor pressure (40 bar) at intermediate temperature (550 °C) in an autoclave device, the used water being almost free or saturated with CO{sub 2}. Such protonation process offers an accelerating stability test and allows the choice of the most pertinent composition for industrial applications requiring a selected material with important life-time. In order to understand any eventual change of crystal structure, the ceramics were investigated in as-prepared, pristine state as well as after protonation and deprotonation (due to thermal treatment till 1000 °C under dry atmosphere). The results show the presence of traces or second phases originating from undesirable hydroxylation and carbonation, detected in the near

  9. Oxidative Stability and Physico-chemical Properties of Meat from Broilers Fed with Dietary Neem Leaf Powder, Spirulina and their Combination

    Directory of Open Access Journals (Sweden)

    Ravi KILLI

    2015-12-01

    Full Text Available This 6 week study was conducted to evaluate the antioxidant potential, maintaining quality and sensory properties of broiler meat from birds fed on dietary neem leaf powder (NLP. A total of 90 Vencobb broiler chicks were randomly allotted to 6 groups of 15 birds in each. Dietary treatments consisted of normal diet (control Group I, feed containing terramycin-200 (TM-200* at the concentration of 0.05% (Group II, feed containing NLP of 0.2% (Group III, feed containing NLP of 0.2% and spirulina of 1% (Group IV, feed containing TM-200 at 0.05% and spirulina of 1% (Group V and feed containing spirulina of 1% (Group VI. At the end of the experiment liver, kidney and muscle samples were collected to evaluate the tissue peroxidation (TBARS and protein carbonyls and antioxidant markers (SOD. Physico-chemical quality determinants of both fresh and preserved meat viz. extract release volume (ERV, water holding capacity (WHC and pH were also studied. TBARS protein carbonyls indicated a significant (P < 0.05 decrease in all the treated groups when compared to control. Superoxide dismutase levels were found to be significantly increased in all the treated groups, in all the tissues collected. Compared to control group, favorable physico-chemical quality determinants were recorded in all the treated groups. The sensory attributes did not show significant (P < 0.05 differences for color, flavor, juiciness, tenderness and overall acceptability. This study indicates enhanced stress tolerance levels, improved meat quality with unaffected consumer acceptance levels of the meat observed in the study, from broilers fed with neem and spirulina either alone or in combinationsș this points out that neem at 0.2% level can be used in poultry diets instead of antibiotic growth promoters (AGP.

  10. Estabilidade físico-química, microbiológica e sensorial de carne ovina embalada a vácuo estocada sob refrigeração Physical and chemical stability microbiological and sensory analysis of vacuum packed sheep meat stored under refrigeration

    Directory of Open Access Journals (Sweden)

    Rafaella de Paula Paseto Fernandes

    2012-04-01

    Full Text Available A carne ovina é comercializada atualmente em sua quase totalidade na forma congelada, porém com a tendência atual de maior procura por produtos de conveniência, vislumbra-se a necessidade de o mercado começar a ofertar esta carne na forma de cortes refrigerados. Este trabalho teve como objetivo avaliar a estabilidade e segurança de lombo de cordeiro embalado a vácuo quando estocado sob refrigeração. A estabilidade foi avaliada por meio de análises físicas e químicas (oxidação lipídica, cor objetiva, valor de pH, composição centesimal, perda de água por cocção e textura instrumental, microbiológicas (contagem total de psicrotróficos anaeróbios, coliformes termotolerantes a 45°C, estafilococos coagulase positiva e presença de Salmonella e sensorial (cor, aparência geral e aroma. A carne ovina apresentou-se estável durante o período de 28 dias com relação à maioria dos índices físicos e químicos avaliados e dentro dos padrões estabelecidos pela legislação brasileira para micro-organismos patogênicos. Durante o armazenamento, detectou-se um aumento elevado das contagens de micro-organismos psicrotróficos anaeróbios, atingindo valores da ordem de 10(7UFC g-1 amostra já aos 14 dias, porém os consumidores não detectaram alterações sensoriais significativas durante todo o período. Conclui-se que a vida útil de lombo ovino armazenado a 4°C é de no mínimo 28 dias.Lamb is commercialized today almost entirely in frozen form, but, considering the current trend to greater demand for convenience products, it becomes more evident the need of availability of chilled cuts of meat in the market. The objective of this study was to evaluate the stability and safety of lamb meat packed under vacuum when stored under refrigeration. The lamb meat samples were packed in high barrier multilayer plastic films and stored under refrigeration (4±1°C. The stability was evaluated by means of physical and chemical analysis

  11. Plasma-Enhanced Chemical Vapor Deposition (PE-CVD) yields better Hydrolytical Stability of Biocompatible SiOx Thin Films on Implant Alumina Ceramics compared to Rapid Thermal Evaporation Physical Vapor Deposition (PVD).

    Science.gov (United States)

    Böke, Frederik; Giner, Ignacio; Keller, Adrian; Grundmeier, Guido; Fischer, Horst

    2016-07-20

    Densely sintered aluminum oxide (α-Al2O3) is chemically and biologically inert. To improve the interaction with biomolecules and cells, its surface has to be modified prior to use in biomedical applications. In this study, we compared two deposition techniques for adhesion promoting SiOx films to facilitate the coupling of stable organosilane monolayers on monolithic α-alumina; physical vapor deposition (PVD) by thermal evaporation and plasma enhanced chemical vapor deposition (PE-CVD). We also investigated the influence of etching on the formation of silanol surface groups using hydrogen peroxide and sulfuric acid solutions. The film characteristics, that is, surface morphology and surface chemistry, as well as the film stability and its adhesion properties under accelerated aging conditions were characterized by means of X-ray photoelectron spectroscopy (XPS), energy dispersive X-ray spectroscopy (EDX), scanning electron microscopy (SEM), inductively coupled plasma-optical emission spectroscopy (ICP-OES), and tensile strength tests. Differences in surface functionalization were investigated via two model organosilanes as well as the cell-cytotoxicity and viability on murine fibroblasts and human mesenchymal stromal cells (hMSC). We found that both SiOx interfaces did not affect the cell viability of both cell types. No significant differences between both films with regard to their interfacial tensile strength were detected, although failure mode analyses revealed a higher interfacial stability of the PE-CVD films compared to the PVD films. Twenty-eight day exposure to simulated body fluid (SBF) at 37 °C revealed a partial delamination of the thermally deposited PVD films whereas the PE-CVD films stayed largely intact. SiOx layers deposited by both PVD and PE-CVD may thus serve as viable adhesion-promoters for subsequent organosilane coupling agent binding to α-alumina. However, PE-CVD appears to be favorable for long-term direct film exposure to aqueous

  12. Theoretical survey on M@C_8_0 (M = Ca, Sr, and Ba): Behavior of different alkaline earth metal impacting the chemical stability and electronic properties

    International Nuclear Information System (INIS)

    Cui, Jin-Bo; Guo, Yi-Jun; Li, Qiao-Zhi; Zhao, Pei; Zhao, Xiang

    2016-01-01

    Structures of mono-metallofullerenes M@C_8_0 (M = Ca, Sr, and Ba) that separated in early experiment are determined owning the C_2_v(31920)-C_8_0 cage. The change rule of properties for M@C_8_0 (M = Ca, Sr, and Ba) influenced by different inner metal are discussed. As the trapped metal changes from calcium to barium, performance of thermodynamic stabilities for M@C_2_v(31920)-C_8_0, M@C_2_v(31922)-C_8_0, and M@D_5_h(31923)-C_8_0 are significantly different. Orbital analysis suggests that the lowest unoccupied molecular orbitals (LUMOs) of Ca@C_2_v(31920)-C_8_0 and Ca@D_5_h(31923)-C_8_0 are mostly located on the trapped metal, whereas reduction reactions of Ca@C_2_v(31920)-C_8_0 and Ca@D_5_h(31923)-C_8_0 occur on the fullerene cage. Natural electron configuration analyses demonstrates that the decentralized electron back-donation of Ba@C_2_v(31920)-C_8_0 would take responsible for the instability of itself. Electronic properties such as electron affinities and ionization potentials are significantly affected by encapsulated metal are also found. Computational UV–visible–NIR spectra for M@C_2_v(31920)-C_8_0 (M = Ca, Sr, Ba) are in perfect accord with the spectra obtained experimentally.

  13. Transformation of Ag nanocubes into Ag-Au hollow nanostructures with enriched Ag contents to improve SERS activity and chemical stability.

    Science.gov (United States)

    Yang, Yin; Zhang, Qiang; Fu, Zheng-Wen; Qin, Dong

    2014-03-12

    We report a strategy to complement the galvanic replacement reaction between Ag nanocubes and HAuCl4 with co-reduction by ascorbic acid (AA) for the formation of Ag-Au hollow nanostructures with greatly enhanced SERS activity. Specifically, in the early stage of synthesis, the Ag nanocubes are sharpened at corners and edges because of the selective deposition of Au and Ag atoms at these sites. In the following steps, the pure Ag in the nanocubes is constantly converted into Ag(+) ions to generate voids owing to the galvanic reaction with HAuCl4, but these released Ag(+) ions are immediately reduced back to Ag atoms and are co-deposited with Au atoms onto the nanocube templates. We observe distinctive SERS properties for the Ag-Au hollow nanostructures at visible and near-infrared excitation wavelengths. When plasmon damping is eliminated by using an excitation wavelength of 785 nm, the SERS activity of the Ag-Au hollow nanostructures is 15- and 33-fold stronger than those of the original Ag nanocubes and the Ag-Au nanocages prepared by galvanic replacement without co-reduction, respectively. Additionally, Ag-Au hollow nanostructures embrace considerably improved stability in an oxidizing environment such as aqueous H2O2 solution. Collectively, our work suggests that the Ag-Au hollow nanostructures will find applications in SERS detection and imaging.

  14. Influence of non-migratory metal-chelating active packaging film on food quality: impact on physical and chemical stability of emulsions.

    Science.gov (United States)

    Tian, Fang; Decker, Eric A; McClements, D Julian; Goddard, Julie M

    2014-05-15

    Previously, we developed a novel metal-chelating packaging film (PP-g-PAA) by grafting acrylic acid (AA) monomer from polypropylene (PP) film surface, and demonstrated its potential in controlling iron-promoted lipid oxidation. Herein, we further established the industrial practicality of this active film. Specifically, the influence of film surface area-to-product volume ratio (SA/V) and product pH on the application of the film was investigated using an oil-in-water emulsion system. The films equally inhibited lipid oxidation throughout the range of SA/V ratios tested (2-8 cm(2)/ml). PP-g-PAA films were most effective at pH 7.0, and the activity decreased with decreasing pH. The particle size examination of emulsions indicated no adverse influence from the active film on the stability of this emulsion system. FTIR analysis suggested a non-migratory nature of PP-g-PAA films. These results provide fundamental knowledge that will facilitate the application of this effective and economical active packaging film in the food industry. Copyright © 2013 Elsevier Ltd. All rights reserved.

  15. Towards Biochar and Hydrochar Engineering—Influence of Process Conditions on Surface Physical and Chemical Properties, Thermal Stability, Nutrient Availability, Toxicity and Wettability

    Directory of Open Access Journals (Sweden)

    Alba Dieguez-Alonso

    2018-02-01

    Full Text Available The impact of conversion process parameters in pyrolysis (maximum temperature, inert gas flow rate and hydrothermal carbonization (maximum temperature, residence time and post-washing on biochar and hydrochar properties is investigated. Pine wood (PW and corn digestate (CD, with low and high inorganic species content respectively, are used as feedstock. CD biochars show lower H/C ratios, thermal recalcitrance and total specific surface area than PW biochars, but higher mesoporosity. CD and PW biochars present higher naphthalene and phenanthrene contents, respectively, which may indicate different reaction pathways. High temperatures (>500 °C lead to lower PAH (polycyclic aromatic hydrocarbons content (<12 mg/kg and higher specific surface area. With increasing process severity the biochars carbon content is also enhanced, as well as the thermal stability. High inert gas flow rates increase the microporosity and wettability of biochars. In hydrochars the high inorganic content favor decarboxylation over dehydration reactions. Hydrochars show mainly mesoporosity, with a higher pore volume but generally lower specific surface area than biochars. Biochars present negligible availability of NO 3 − and NH 4 + , irrespective of the nitrogen content of the feedstock. For hydrochars, a potential increase in availability of NO 3 − , NH 4 + , PO 4 3 − , and K + with respect to the feedstock is possible. The results from this work can be applied to “engineer” appropriate biochars with respect to soil demands and certification requirements.

  16. Durabilidade de solos estabilizados quimicamente com vistas á aplicação em estradas florestais Durability of chemically stabilized soils for forest road applications

    Directory of Open Access Journals (Sweden)

    Carlos Cardoso Machado

    2006-12-01

    Full Text Available Este artigo é direcionado à caracterização do parâmetro durabilidade de dois solos típicos da microrregião de Viçosa, Minas Gerais, para fins de aplicação em estradas florestais, considerando-se, para tanto, as seguintes condições: (a solos estabilizados com o resíduo industrial "grits"; (b solos melhorados com cal ou cimento; e (c solos estabilizados com grits e melhorados com cal ou cimento, a partir de resultados de ensaios de durabilidade por molhagem e secagem. Trabalhou-se com um solo residual maduro (solo 1 e um solo residual jovem de gnaisse (solo 2 da Zona da Mata Norte de Minas Gerais, Brasil. O programa de ensaios de laboratório envolveu: (a teor de grits: 24% calculado em relação ao peso de solo seco; (b teor de cal ou cimento: 10 e 20%, calculados em relação ao peso de grits seco; (c energias de compactação: referentes aos ensaios Proctor normal e modificado; e (d período de cura: sete dias em câmara úmida. Os resultados do programa de ensaios indicaram que: (a as misturas solo-cal, solo-cimento, solo-grits-cal e solo-grits-cimento, em ambas as energias empregadas, resistiram a todos os ciclos do ensaio de durabilidade por molhagem e secagem; (b a mistura solo 1 + grits + cal apresentou o melhor resultado, quando compactada na energia modificada, com perdas da ordem de 7%; com relação ao solo 2, o melhor resultado foi obtido quando se trabalhou com grits mais cimento, na energia modificada, com perdas da ordem de 9%; e (c sob o aspecto durabilidade, as misturas solo-grits só apresentam potencial para emprego como material de construção rodoviária quando melhoradas com cal ou cimento.This paper addresses the assessment of the durability properties of mixtures of two soils using laboratory wetting and drying durability tests for forest road applications, as follows: (a soils stabilization with the industrial waste grits; (b soil improvement using lime or cement; (c soil stabilization using grits, and soil

  17. Chemical Reactivity Test (CRT)

    Energy Technology Data Exchange (ETDEWEB)

    Zaka, F. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2016-12-13

    The Chemical Reactivity Test (CRT) is used to determine the thermal stability of High Explosives (HEs) and chemical compatibility between (HEs) and alien materials. The CRT is one of the small-scale safety tests performed on HE at the High Explosives Applications Facility (HEAF).

  18. Ultra-thin g-C{sub 3}N{sub 4} nanosheets wrapped silicon nanowire array for improved chemical stability and enhanced photoresponse

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Beibei; Yu, Hongtao; Quan, Xie, E-mail: quanxie@dlut.edu.cn; Chen, Shuo

    2014-11-15

    Highlights: • g-C{sub 3}N{sub 4}, as an oxygen free and metal free protective material for Si, was proposed. • g-C{sub 3}N{sub 4} nanosheets wrapped Si nanowire array was synthesized. • SiNW/g-C{sub 3}N{sub 4} exhibited enhancement of photoelectrochemical stability and photocurrent. - Abstract: In order to inhibit the oxidation of Si materials in aqueous solution, Si nanowire array was wrapped by ultra-thin g-C{sub 3}N{sub 4} nanosheets via an electrophoresis process. Scanning electron microscopy and transmission electron microscopy images showed that g-C{sub 3}N{sub 4} nanosheets were evenly distributed on the surface of Si nanowire array. X-ray diffraction patterns indicated that Si nanowire array/g-C{sub 3}N{sub 4} nanosheets were composed of Si (4 0 0 crystal plane) and g-C{sub 3}N{sub 4} (0 0 2 and 1 0 0 crystal planes). The cyclic voltammetry curves revealed that the corrosion of Si nanowire array was restrained under the protection of g-C{sub 3}N{sub 4} nanosheets. Furthermore, the photocurrent density of Si nanowire array/g-C{sub 3}N{sub 4} nanosheets increased by nearly 3 times compared to that of bare Si nanowire array due to the effective charge separation caused by the built-in electric field at the interface. This work will facilitate the applications of Si materials in aqueous solution, such as solar energy harvest and photocatalytic pollution control.

  19. Theoretical survey on M@C{sub 80} (M = Ca, Sr, and Ba): Behavior of different alkaline earth metal impacting the chemical stability and electronic properties

    Energy Technology Data Exchange (ETDEWEB)

    Cui, Jin-Bo; Guo, Yi-Jun; Li, Qiao-Zhi; Zhao, Pei; Zhao, Xiang, E-mail: xzhao@mail.xjtu.edu.cn

    2016-08-02

    Structures of mono-metallofullerenes M@C{sub 80} (M = Ca, Sr, and Ba) that separated in early experiment are determined owning the C{sub 2v}(31920)-C{sub 80} cage. The change rule of properties for M@C{sub 80} (M = Ca, Sr, and Ba) influenced by different inner metal are discussed. As the trapped metal changes from calcium to barium, performance of thermodynamic stabilities for M@C{sub 2v}(31920)-C{sub 80}, M@C{sub 2v}(31922)-C{sub 80}, and M@D{sub 5h}(31923)-C{sub 80} are significantly different. Orbital analysis suggests that the lowest unoccupied molecular orbitals (LUMOs) of Ca@C{sub 2v}(31920)-C{sub 80} and Ca@D{sub 5h}(31923)-C{sub 80} are mostly located on the trapped metal, whereas reduction reactions of Ca@C{sub 2v}(31920)-C{sub 80} and Ca@D{sub 5h}(31923)-C{sub 80} occur on the fullerene cage. Natural electron configuration analyses demonstrates that the decentralized electron back-donation of Ba@C{sub 2v}(31920)-C{sub 80} would take responsible for the instability of itself. Electronic properties such as electron affinities and ionization potentials are significantly affected by encapsulated metal are also found. Computational UV–visible–NIR spectra for M@C{sub 2v}(31920)-C{sub 80} (M = Ca, Sr, Ba) are in perfect accord with the spectra obtained experimentally.

  20. Greater trochanteric fracture with occult intertrochanteric extension.

    Science.gov (United States)

    Reiter, Michael; O'Brien, Seth D; Bui-Mansfield, Liem T; Alderete, Joseph

    2013-10-01

    Proximal femoral fractures are frequently encountered in the emergency department (ED). Prompt diagnosis is paramount as delay will exacerbate the already poor outcomes associated with these injuries. In cases where radiography is negative but clinical suspicion remains high, magnetic resonance imaging (MRI) is the study of choice as it has the capability to depict fractures which are occult on other imaging modalities. Awareness of a particular subset of proximal femoral fractures, namely greater trochanteric fractures, is vital for both radiologists and clinicians since it has been well documented that they invariably have an intertrochanteric component which may require surgical management. The detection of intertrochanteric or cervical extension of greater trochanteric fractures has been described utilizing MRI but is underestimated with both computed tomography (CT) and bone scan. Therefore, if MRI is unavailable or contraindicated, the diagnosis of an isolated greater trochanteric fracture should be met with caution. The importance of avoiding this potential pitfall is demonstrated in the following case of an elderly woman with hip pain and CT demonstrating an isolated greater trochanteric fracture who subsequently returned to the ED with a displaced intertrochanteric fracture.

  1. Butterfly valves: greater use in power plants

    International Nuclear Information System (INIS)

    McCoy, M.

    1975-01-01

    Improvements in butterfly valves, particularly in the areas of automatic control and leak tightness are described. The use of butterfly valves in nuclear power plants is discussed. These uses include service in component cooling, containment cooling, and containment isolation. The outlook for further improvements and greater uses is examined. (U.S.)

  2. Greater Somalia, the never-ending dream?

    DEFF Research Database (Denmark)

    Zoppi, Marco

    2015-01-01

    This paper provides an historical analysis of the concept of Greater Somalia, the nationalist project that advocates the political union of all Somali-speaking people, including those inhabiting areas in current Djibouti, Ethiopia and Kenya. The Somali territorial unification project of “lost...

  3. Luminescence process, refractory stabilities, and new novel electronic states: scanning chemical reactions and novel products for laser induced isotope separation. Progress report, December 1, 1975--July 15, 1976

    International Nuclear Information System (INIS)

    Gole, J.L.

    1976-08-01

    The formulation, development, and use of versatile oven systems for high temperature metal vaporization at temperatures in excess of 2000 0 C are discussed. Refinements of an apparatus appropriate for the production and study of small metal aggregates M/sub n/(2 less than or equal to n less than or equal to 6) are discussed at length. Improvements in the argon ion and nitrogen pumped dye laser systems, and necessary additions for effective interfacing of these dye lasers to the aggregates apparatus are described. Internal calibration standards are discussed. Progress on the production of carbon vapor and the reaction of this vapor with metal atoms and metal dimers to form metal carbides is outlined. Metal sulfide chemistry is discussed. Several specific studies of the luminescence process are outlined. Included in these studies are completed work on aluminum oxidation. Studies of germanium and silicon oxidation are outlined, and new investigations of inorganic hydride oxidation are presented. The status of our efforts to form new and novel surfaces via aggregate deposition is outlined. Quantum chemical calculations on small metal aggregates are discussed. The first applications of dynamic laser induced fluorescence to the AlO molecule are presented

  4. Chemical characterization and oxidative stability of the oils from three morphotypes of Mauritia flexuosa L.f, from the Peruvian Amazon

    Directory of Open Access Journals (Sweden)

    Mancini-Filho, Jorge

    2010-12-01

    Full Text Available Three morphotypes of aguaje Mauritia flexuosa were tested, classified by the color of their mesocarpium: “color”, “shambo” and “amarillo”, collected from different areas near the city of Iquitos, Peru. Also, physical-chemical analyses of the mesocarpium were performed, such as the characterization of fatty acids by gas chromatography, determination of β- carotene y α – tocopherol by high efficiency liquid chromatography system in normal and reverse phase and the determination of oxidation induction time in the Rancimat apparatus. Proximate, mineral and fatty acid analyses were done on the seeds. The aguaje mesocarpium is rich in oleic oil (“amarillo”: 75.63% ± 0.31, β-carotene (“amarillo”: 342.42ug/g ± 0.71 and α- tocopherol (“color”: 685.81mg/L ± 1.04, plus the morphotype “color” has a superior oxidation induction time compared to other morphotypes with 6.91 ± 0.01. The aguaje seed contains significant amounts of ω6 (linoleic oil in “shambo” with 36.04 ± 0.09%. The results indicate that these oils, regardless their classification, contain important chemical compounds that give them a special nutritive value.Se estudiaron tres morfotipos de aguaje Mauritia flexuosa L. f., clasificados por el color del mesocarpio: “color”, “shambo” y “amarillo”, recogidos de localidades cercanas a la ciudad de Iquitos- Perú. Del mismo modo a partir del mesocarpio se realizaron los análisis fisicoquímicos, la caracterización de los ácidos grasos por cromatografía gaseosa, la determinación de β-caroteno y α– tocoferol por cromatografía líquida de alta eficiencia (HPLC fase reversa y normal y la determinación del tiempo de inducción de la oxidación en el equipo de Rancimat. A partir de la semilla se realizaron los análisis centesimales, de minerales y ácidos grasos. Los mesocarpios de aguaje son ricos en ácido oleico (amarillo: 75.63% ± 0.31, β-caroteno (amarillo: 342.42 ug/g ± 0.71 y

  5. Osmium(III) analogues of KP1019: Electrochemical and chemical synthesis, spectroscopic characterization, x-ray crystallography, hydrolytic stability, and antiproliferative activity

    KAUST Repository

    Kuhn, Paul-Steffen

    2014-10-20

    A one-electron reduction of osmium(IV) complexes trans-[OsIVCl4(Hazole)2], where Hazole = 1H-pyrazole ([1]0), 2H-indazole ([2]0), 1H-imidazole ([3]0), and 1H-benzimidazole ([4]0), afforded a series of eight new complexes as osmium analogues of KP1019, a lead anticancer drug in clinical trials, with the general formula (cation)[trans-OsIIICl4(Hazole)2], where cation = H2pz+ (H2pz[1]), H2ind+ (H2ind[2]), H2im+ (H2im[3]), Ph4P+ (Ph4P[3]), nBu4N+ (nBu4N[3]), H2bzim+ (H2bzim[4]), Ph4P+ (Ph4P[4]), and nBu4N+ (nBu4N[4]). All complexes were characterized by elemental analysis, 1H NMR spectroscopy, electrospray ionization mass spectrometry, UV-vis spectroscopy, cyclic voltammetry, while H2pz[1], H2ind[2], and nBu4[3], in addition, by X-ray diffraction. The reduced species [1]- and [4]- are stable in aqueous media in the absence of air oxygen and do not react with small biomolecules such as amino acids and the nucleotide 5′-dGMP. Cell culture experiments in five different human cancer cell lines (HeLa, A549, FemX, MDA-MB-453, and LS-174) and one noncancerous cell line (MRC-5) were performed, and the results were discussed and compared to those for KP1019 and cisplatin. Benzannulation in complexes with similar structure enhances antitumor activity by several orders of magnitude, implicating different mechanisms of action of the tested compounds. In particular, complexes H2ind[2] and H2bzim[4] exhibited significant antiproliferative activity in vitro when compared to H2pz[1] and H2im[3]. (Chemical Equation Presented).

  6. Osmium(III) analogues of KP1019: Electrochemical and chemical synthesis, spectroscopic characterization, x-ray crystallography, hydrolytic stability, and antiproliferative activity

    KAUST Repository

    Kuhn, Paul-Steffen; Bü chel, Gabriel E.; Jovanović, Katarina K.; Filipović, Lana; Radulović, Siniša S.; Rapta, Peter; Arion, Vladimir B.

    2014-01-01

    A one-electron reduction of osmium(IV) complexes trans-[OsIVCl4(Hazole)2], where Hazole = 1H-pyrazole ([1]0), 2H-indazole ([2]0), 1H-imidazole ([3]0), and 1H-benzimidazole ([4]0), afforded a series of eight new complexes as osmium analogues of KP1019, a lead anticancer drug in clinical trials, with the general formula (cation)[trans-OsIIICl4(Hazole)2], where cation = H2pz+ (H2pz[1]), H2ind+ (H2ind[2]), H2im+ (H2im[3]), Ph4P+ (Ph4P[3]), nBu4N+ (nBu4N[3]), H2bzim+ (H2bzim[4]), Ph4P+ (Ph4P[4]), and nBu4N+ (nBu4N[4]). All complexes were characterized by elemental analysis, 1H NMR spectroscopy, electrospray ionization mass spectrometry, UV-vis spectroscopy, cyclic voltammetry, while H2pz[1], H2ind[2], and nBu4[3], in addition, by X-ray diffraction. The reduced species [1]- and [4]- are stable in aqueous media in the absence of air oxygen and do not react with small biomolecules such as amino acids and the nucleotide 5′-dGMP. Cell culture experiments in five different human cancer cell lines (HeLa, A549, FemX, MDA-MB-453, and LS-174) and one noncancerous cell line (MRC-5) were performed, and the results were discussed and compared to those for KP1019 and cisplatin. Benzannulation in complexes with similar structure enhances antitumor activity by several orders of magnitude, implicating different mechanisms of action of the tested compounds. In particular, complexes H2ind[2] and H2bzim[4] exhibited significant antiproliferative activity in vitro when compared to H2pz[1] and H2im[3]. (Chemical Equation Presented).

  7. Utilization of wind energy in greater Hanover

    International Nuclear Information System (INIS)

    Sahling, U.

    1993-01-01

    Since the beginning of the Eighties, the association of communities of Greater Hanover has dealt intensively with energy and ecopolitical questions in the scope of regional planning. Renewable energy sources play a dominant role in this context. This brochure is the third contribution to the subject ''Energy policy and environmental protection''. Experts as well as possibly interested parties are addressed especially. For all 8 contributions contained, separate entries have been recorded in this database. (BWI) [de

  8. Small cities face greater impact from automation

    OpenAIRE

    Frank, Morgan R.; Sun, Lijun; Cebrian, Manuel; Youn, Hyejin; Rahwan, Iyad

    2017-01-01

    The city has proven to be the most successful form of human agglomeration and provides wide employment opportunities for its dwellers. As advances in robotics and artificial intelligence revive concerns about the impact of automation on jobs, a question looms: How will automation affect employment in cities? Here, we provide a comparative picture of the impact of automation across U.S. urban areas. Small cities will undertake greater adjustments, such as worker displacement and job content su...

  9. The Greater Sekhukhune-CAPABILITY outreach project.

    Science.gov (United States)

    Gregersen, Nerine; Lampret, Julie; Lane, Tony; Christianson, Arnold

    2013-07-01

    The Greater Sekhukhune-CAPABILITY Outreach Project was undertaken in a rural district in Limpopo, South Africa, as part of the European Union-funded CAPABILITY programme to investigate approaches for capacity building for the translation of genetic knowledge into care and prevention of congenital disorders. Based on previous experience of a clinical genetic outreach programme in Limpopo, it aimed to initiate a district clinical genetic service in Greater Sekhukhune to gain knowledge and experience to assist in the implementation and development of medical genetic services in South Africa. Implementing the service in Greater Sekhukhune was impeded by a developing staff shortage in the province and pressure on the health service from the existing HIV/AIDS and TB epidemics. This situation underscores the need for health needs assessment for developing services for the care and prevention of congenital disorders in middle- and low-income countries. However, these impediments stimulated the pioneering of innovate ways to offer medical genetic services in these circumstances, including tele-teaching of nurses and doctors, using cellular phones to enhance clinical care and adapting and assessing the clinical utility of a laboratory test, QF-PCR, for use in the local circumstances.

  10. Operational technology for greater confinement disposal

    International Nuclear Information System (INIS)

    Dickman, P.T.; Vollmer, A.T.; Hunter, P.H.

    1984-12-01

    Procedures and methods for the design and operation of a greater confinement disposal facility using large-diameter boreholes are discussed. It is assumed that the facility would be located at an operating low-level waste disposal site and that only a small portion of the wastes received at the site would require greater confinement disposal. The document is organized into sections addressing: facility planning process; facility construction; waste loading and handling; radiological safety planning; operations procedures; and engineering cost studies. While primarily written for low-level waste management site operators and managers, a detailed economic assessment section is included that should assist planners in performing cost analyses. Economic assessments for both commercial and US government greater confinement disposal facilities are included. The estimated disposal costs range from $27 to $104 per cubic foot for a commercial facility and from $17 to $60 per cubic foot for a government facility. These costs are based on average site preparation, construction, and waste loading costs for both contact- and remote-handled wastes. 14 figures, 22 tables

  11. Greater-confinement disposal of low-level radioactive wastes

    International Nuclear Information System (INIS)

    Trevorrow, L.E.; Gilbert, T.L.; Luner, C.; Merry-Libby, P.A.; Meshkov, N.K.; Yu, C.

    1985-01-01

    Low-level radioactive wastes include a broad spectrum of wastes that have different radionuclide concentrations, half-lives, and physical and chemical properties. Standard shallow-land burial practice can provide adequate protection of public health and safety for most low-level wastes, but a small volume fraction (about 1%) containing most of the activity inventory (approx.90%) requires specific measures known as ''greater-confinement disposal'' (GCD). Different site characteristics and different waste characteristics - such as high radionuclide concentrations, long radionuclide half-lives, high radionuclide mobility, and physical or chemical characteristics that present exceptional hazards - lead to different GCD facility design requirements. Facility design alternatives considered for GCD include the augered shaft, deep trench, engineered structure, hydrofracture, improved waste form, and high-integrity container. Selection of an appropriate design must also consider the interplay between basic risk limits for protection of public health and safety, performance characteristics and objectives, costs, waste-acceptance criteria, waste characteristics, and site characteristics. This paper presents an overview of the factors that must be considered in planning the application of methods proposed for providing greater confinement of low-level wastes. 27 refs

  12. Magnet stability and reproducibility

    CERN Document Server

    Marks, N

    2010-01-01

    Magnet stability and reproducibility have become increasingly important as greater precision and beams with smaller dimension are required for research, medical and other purpose. The observed causes of mechanical and electrical instability are introduced and the engineering arrangements needed to minimize these problems discussed; the resulting performance of a state-of-the-art synchrotron source (Diamond) is then presented. The need for orbit feedback to obtain best possible beam stability is briefly introduced, but omitting any details of the necessary technical equipment, which is outside the scope of the presentation.

  13. Stability of loess

    Science.gov (United States)

    Lutenegger, A.J.; Hallberg, G.R.

    1988-01-01

    Lutenegger, A.J. and Hallberg, G.R., 1988. Stability of loess. Eng. Geol., 25: 247-261. The natural stability of loess soils can be related to fundamental geotechnical properties such as Atterberg limits, water content and void ratio. Field observations of unstable conditions in loess deposits in the upper midwest, U.S.A. show relationships between instability and the in situ moisture content and the liquidity index of the loess. Unstable loess can attain natural moisture contents equal to, or greater than, its liquid limit. Implications of these observations for applied engineering works are described. ?? 1988.

  14. Greater happiness for a greater number: Is that possible in Austria?

    NARCIS (Netherlands)

    R. Veenhoven (Ruut)

    2011-01-01

    textabstractWhat is the final goal of public policy? Jeremy Bentham (1789) would say: greater happiness for a greater number. He thought of happiness as subjective enjoyment of life; in his words as “the sum of pleasures and pains”. In his time the happiness of the great number could not be measured

  15. Greater happiness for a greater number: Is that possible? If so how? (Arabic)

    NARCIS (Netherlands)

    R. Veenhoven (Ruut); E. Samuel (Emad)

    2012-01-01

    textabstractWhat is the final goal of public policy? Jeremy Bentham (1789) would say: greater happiness for a greater number. He thought of happiness as subjective enjoyment of life; in his words as “the sum of pleasures and pains”. In his time, the happiness of the great number could not be

  16. Greater happiness for a greater number: Is that possible in Germany?

    NARCIS (Netherlands)

    R. Veenhoven (Ruut)

    2009-01-01

    textabstractWhat is the final goal of public policy? Jeremy Bentham (1789) would say: greater happiness for a greater number. He thought of happiness as subjective enjoyment of life; in his words as “the sum of pleasures and pains”. In his time the Happiness of the great number could not be measured

  17. Greater confinement disposal program at the Savannah River Plant

    International Nuclear Information System (INIS)

    Cook, J.R.; Towler, O.A.; Peterson, D.L.; Johnson, G.M.; Helton, B.D.

    1984-01-01

    The first facility to demonstrate Greater Confinement Disposal (GCD) in a humid environment in the United States has been built and is operating at the Savannah River Plant. GCD practices of waste segregation, packaging, emplacement below the root zone, and waste stabilization are being used in the demonstration. Activity concentrations to select wastes for GCD are based on a study of SRP burial records, and are equal to or less than those for Class B waste in 10CFR61. The first disposal units to be constructed are 9-foot diameter, thirty-foot deep boreholes which will be used to dispose of wastes from production reactors, tritiated wastes, and selected wastes from off-site. In 1984 an engineered GCD trench will be constructed for disposal of boxed wastes and large bulky items. 2 figures, 1 table

  18. Greater Confinement Disposal Program at the Savannah River Plant

    International Nuclear Information System (INIS)

    Towler, O.A.; Cook, J.R.; Peterson, D.L.

    1983-01-01

    Plans for improved LLW disposal at the Savannah River Plant include Greater Confinement Disposal (GCD) for the higher activity fractions of this waste. GCD practices will include waste segregation, packaging, emplacement below the root zone, and stabilizing the emplacement with cement. Statistical review of SRP burial records showed that about 95% of the radioactivity is associated with only 5% of the waste volume. Trigger values determined in this study were compared with actual burials in 1982 to determine what GCD facilities would be needed for a demonstration to begin in Fall 1983. Facilities selected include 8-feet-diameter x 30-feet-deep boreholes to contain reactor scrap, tritiated waste, and selected wastes from offsite

  19. Greater Sudbury fuel efficient driving handbook

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2009-12-15

    Reducing the amount of fuel that people use for personal driving saves money, improves local air quality, and reduces personal contributions to climate change. This handbook was developed to be used as a tool for a fuel efficient driving pilot program in Greater Sudbury in 2009-2010. Specifically, the purpose of the handbook was to provide greater Sudbury drivers with information on how to drive and maintain their personal vehicles in order to maximize fuel efficiency. The handbook also provides tips for purchasing fuel efficient vehicles. It outlines the benefits of fuel maximization, with particular reference to reducing contributions to climate change; reducing emissions of air pollutants; safe driving; and money savings. Some tips for efficient driving are to avoid aggressive driving; use cruise control; plan trips; and remove excess weight. Tips for efficient winter driving are to avoid idling to warm up the engine; use a block heater; remove snow and ice; use snow tires; and check tire pressure. The importance of car maintenance and tire pressure was emphasized. The handbook also explains how fuel consumption ratings are developed by vehicle manufacturers. refs., figs.

  20. Women at greater risk of HIV infection.

    Science.gov (United States)

    Mahathir, M

    1997-04-01

    Although many people believe that mainly men get infected with HIV/AIDS, women are actually getting infected at a faster rate than men, especially in developing countries, and suffer more from the adverse impact of AIDS. As of mid-1996, the Joint UN Program on AIDS estimated that more than 10 million of the 25 million adults infected with HIV since the beginning of the epidemic are women. The proportion of HIV-positive women is growing, with almost half of the 7500 new infections daily occurring among women. 90% of HIV-positive women live in a developing country. In Asia-Pacific, 1.4 million women have been infected with HIV out of an estimated total 3.08 million adults from the late 1970s until late 1994. Biologically, women are more vulnerable than men to infection because of the greater mucus area exposed to HIV during penile penetration. Women under age 17 years are at even greater risk because they have an underdeveloped cervix and low vaginal mucus production. Concurrent sexually transmitted diseases increase the risk of HIV transmission. Women's risk is also related to their exposure to gender inequalities in society. The social and economic pressures of poverty exacerbate women's risk. Prevention programs are discussed.

  1. Small cities face greater impact from automation.

    Science.gov (United States)

    Frank, Morgan R; Sun, Lijun; Cebrian, Manuel; Youn, Hyejin; Rahwan, Iyad

    2018-02-01

    The city has proved to be the most successful form of human agglomeration and provides wide employment opportunities for its dwellers. As advances in robotics and artificial intelligence revive concerns about the impact of automation on jobs, a question looms: how will automation affect employment in cities? Here, we provide a comparative picture of the impact of automation across US urban areas. Small cities will undertake greater adjustments, such as worker displacement and job content substitutions. We demonstrate that large cities exhibit increased occupational and skill specialization due to increased abundance of managerial and technical professions. These occupations are not easily automatable, and, thus, reduce the potential impact of automation in large cities. Our results pass several robustness checks including potential errors in the estimation of occupational automation and subsampling of occupations. Our study provides the first empirical law connecting two societal forces: urban agglomeration and automation's impact on employment. © 2018 The Authors.

  2. Small cities face greater impact from automation

    Science.gov (United States)

    Sun, Lijun; Cebrian, Manuel; Rahwan, Iyad

    2018-01-01

    The city has proved to be the most successful form of human agglomeration and provides wide employment opportunities for its dwellers. As advances in robotics and artificial intelligence revive concerns about the impact of automation on jobs, a question looms: how will automation affect employment in cities? Here, we provide a comparative picture of the impact of automation across US urban areas. Small cities will undertake greater adjustments, such as worker displacement and job content substitutions. We demonstrate that large cities exhibit increased occupational and skill specialization due to increased abundance of managerial and technical professions. These occupations are not easily automatable, and, thus, reduce the potential impact of automation in large cities. Our results pass several robustness checks including potential errors in the estimation of occupational automation and subsampling of occupations. Our study provides the first empirical law connecting two societal forces: urban agglomeration and automation's impact on employment. PMID:29436514

  3. Planning for greater-confinement disposal

    International Nuclear Information System (INIS)

    Gilbert, T.L.; Luner, C.; Meshkov, N.K.; Trevorrow, L.E.; Yu, C.

    1984-01-01

    This contribution is a progress report for preparation of a document that will summarize procedures and technical information needed to plan for and implement greater-confinement disposal (GCD) of low-level radioactive waste. Selection of a site and a facility design (Phase I), and construction, operation, and extended care (Phase II) will be covered in the document. This progress report is limited to Phase I. Phase I includes determination of the need for GCD, design alternatives, and selection of a site and facility design. Alternative designs considered are augered shafts, deep trenches, engineered structures, high-integrity containers, hydrofracture, and improved waste form. Design considerations and specifications, performance elements, cost elements, and comparative advantages and disadvantages of the different designs are covered. Procedures are discussed for establishing overall performance objectives and waste-acceptance criteria, and for comparative assessment of the performance and cost of the different alternatives. 16 references

  4. Planning for greater-confinement disposal

    International Nuclear Information System (INIS)

    Gilbert, T.L.; Luner, C.; Meshkov, N.K.; Trevorrow, L.E.; Yu, C.

    1984-01-01

    This contribution is a progress report for preparation of a document that will summarize procedures and technical information needed to plan for and implement greater-confinement disposal (GCD) of low-level radioactive waste. Selection of a site and a facility design (Phase I), and construction, operation, and extended care (Phase II) will be covered in the document. This progress report is limited to Phase I. Phase I includes determination of the need for GCD, design alternatives, and selection of a site and facility design. Alternative designs considered are augered shafts, deep trenches, engineered structures, high-integrity containers, hydrofracture, and improved waste form. Design considerations and specifications, performance elements, cost elements, and comparative advantages and disadvantages of the different designs are covered. Procedures are discussed for establishing overall performance objecties and waste-acceptance criteria, and for comparative assessment of the performance and cost of the different alternatives. 16 refs

  5. Computationally designed libraries for rapid enzyme stabilization

    NARCIS (Netherlands)

    Wijma, Hein J.; Floor, Robert J.; Jekel, Peter A.; Baker, David; Marrink, Siewert J.; Janssen, Dick B.

    The ability to engineer enzymes and other proteins to any desired stability would have wide-ranging applications. Here, we demonstrate that computational design of a library with chemically diverse stabilizing mutations allows the engineering of drastically stabilized and fully functional variants

  6. Chemical Peels

    Science.gov (United States)

    ... care Kids’ zone Video library Find a dermatologist Chemical peels Overview Chemical peels: Overview Also called chemexfoliation , derma peeling Do ... Overview Chemical peels: FAQs Chemical peels: Preparation FAQs Chemical peels: FAQs To help you decide whether this ...

  7. Oak Ridge greater confinement disposal demonstrations

    International Nuclear Information System (INIS)

    Van Hoesen, S.D.; Clapp, R.B.

    1987-01-01

    Demonstrations are being conducted in association with the disposal of a high activity low-level waste (LLW) stream. The waste stream in question will result from the cement solidification of decanted liquids from the Melton Valley Storage Tanks (MVST). The solid waste will be produced beginning in mid summer 1988. It is anticipated to have significant concentrations of Cs-137 and Sr-90, with smaller amounts of other radionuclides and <100 nCi/gm of TRU. The solid waste forms are expected to have surface dose rates in the 1 to 2 r/hr range. The solid waste will also contain several chemical species at concentrations which are below those of concern, but which may present enhanced corrosion potential for the disposal units. 2 refs., 5 figs

  8. Plastic Foam Withstands Greater Temperatures And Pressures

    Science.gov (United States)

    Cranston, John A.; Macarthur, Doug

    1993-01-01

    Improved plastic foam suitable for use in foam-core laminated composite parts and in tooling for making fiber/matrix-composite parts. Stronger at high temperatures, more thermally and dimensionally stable, machinable, resistant to chemical degradation, and less expensive. Compatible with variety of matrix resins. Made of polyisocyanurate blown with carbon dioxide and has density of 12 to 15 pounds per cubic feet. Does not contibute to depletion of ozone from atmosphere. Improved foam used in cores of composite panels in such diverse products as aircraft, automobiles, railroad cars, boats, and sporting equipment like surfboards, skis, and skateboards. Also used in thermally stable flotation devices in submersible vehicles. Machined into mandrels upon which filaments wound to make shells.

  9. On the Chemical Stabilities of Ionic Liquids

    OpenAIRE

    Yen-Ho Chu; Ming-Chung Tseng; Venkatesan Srinivasadesikan; Subbiah Sowmiah

    2009-01-01

    Ionic liquids are novel solvents of interest as greener alternatives to conventional organic solvents aimed at facilitating sustainable chemistry. As a consequence of their unusual physical properties, reusability, and eco-friendly nature, ionic liquids have attracted the attention of organic chemists. Numerous reports have revealed that many catalysts and reagents were supported in the ionic liquid phase, resulting in enhanced reactivity and selectivity in various important reaction transfor...

  10. Urban acid deposition in Greater Manchester

    Energy Technology Data Exchange (ETDEWEB)

    Lee, D.S.; Longhurst, J.W.S.; Gee, D.R.; Hare, S.E. (Manchester Polytechnic, Manchester (UK). Acid Rain Information Centre)

    1989-08-01

    Data are presented from a monitoring network of 18 bulk precipitation collectors and one wet-only collector in the urban area of Greater Manchester, in the north west of England. Weekly samples were analysed for all the major ions in precipitation along with gaseous nitrogen dioxide concentrations from diffusion tubes. Statistical analysis of the data shows significant spatial variation of non marine sulphate, nitrate, ammonium, acidity and calcium concentrations, and nitrogen dioxide concentrations. Calcium is thought to be responsible for the buffering of acidity and is of local origin. Wet deposition is the likely removal process for calcium in the atmosphere and probably by below cloud scavenging. Nitrate and ammonium concentrations and depositions show close spatial, temporal and statistical association. Examination of high simultaneous episodes of nitrate and ammonium deposition shows that these depositions cannot be explained in terms of trajectories and it is suggested that UK emissions of ammonia may be important. Statistical analysis of the relationships between nitrate and ammonium depositions, concentrations and precipitation amount suggest that ammonia from mesoscale sources reacts reversibly with nitric acid aerosol and is removed by below cloud scavenging. High episodes of the deposition of non marine sulphate are difficult to explain by trajectory analysis alone, perhaps suggesting local sources. In a comparison between wet deposition and bulk deposition, it was shown that only 15.2% of the non marine sulphur was dry deposited to the bulk precipitation collector. 63 refs., 86 figs., 31 tabs.

  11. Stabilizing Niger

    DEFF Research Database (Denmark)

    Hahonou, Eric Komlavi

    international intervention in Niger. Their main objective is to secure their own strategic, economic and political interests by strengthening the Nigerien authorities through direct intervention and capacity building activities. For western states reinforcing state security institutions and stabilizing elite...

  12. Vapour cloud explosion hazard greater with light feedstocks

    Energy Technology Data Exchange (ETDEWEB)

    Windebank, C.S.

    1980-03-03

    Because lighter chemical feedstocks such as propylene and butylenes are more reactive than LPG's they pose a greater risk of vapor cloud explosion, particularly during their transport. According to C.S. Windebank (Insurance Tech. Bur.), percussive unconfined vapor cloud explosions (PUVCE's) do not usually occur below the ten-ton threshold for saturated hydrocarbons but can occur well below this threshold in the case of unsaturated hydrocarbons such as propylene and butylenes. Boiling liquid expanding vapor explosions (BLEVE's) are more likely to be ''hot'' (i.e., the original explosion is associated with fire) than ''cold'' in the case of unsaturated hydrocarbons. No PUVCE or BLEVE incident has been reported in the UK. In the US, 16 out of 20 incidents recorded between 1970 and 1975 were related to chemical feedstocks, including propylene and butylenes, and only 4 were LPG-related. The average losses were $20 million per explosion. Between 1968 and 1978, 8% of LPG pipeline spillages led to explosions.

  13. Chemical Emergencies

    Science.gov (United States)

    When a hazardous chemical has been released, it may harm people's health. Chemical releases can be unintentional, as in the case of an ... the case of a terrorist attack with a chemical weapon. Some hazardous chemicals have been developed by ...

  14. Facile, one-pot and scalable synthesis of highly emissive aqueous-based Ag,Ni:ZnCdS/ZnS core/shell quantum dots with high chemical and optical stability

    Science.gov (United States)

    Sahraei, Reza; Soheyli, Ehsan; Faraji, Zahra; Soleiman-Beigi, Mohammad

    2017-11-01

    We report here on a one-pot, mild and low cost aqueous-based synthetic route for the preparation of colloidally stable and highly luminescent dual-doped Ag,Ni:ZnCdS/ZnS core/shell quantum dots (QDs). The pure dopant emission of the Ni-doped core/shell QDs was found to be highly affected by the presence of a second dopant ion (Ag+). Results showed that the PL emission intensity increases while its peak position experiences an obvious blue shift with an increase in the content of Ag+ ions. Regarding the optical observations, we provide a simple scheme for absorption-recombination processes of the carriers through impurity centers. To obtain optimum conditions with a better emission characteristic, we also study the effect of different reaction parameters, such as refluxing temperature, the pH of the core and shell solution, molar ratio of the dopant ions (Ni:(Zn+Cd) and Ag:(Zn+Cd)), and concentration of the core and shell precursors. Nonetheless, the most effective parameter is the presence of the ZnS shell in a suitable amount to eliminate surface trap states and enhance their emission intensity. It can also improve the bio-compatibility of the prepared QDs by restricting the Cd2+ toxic ions inside the core of the QDs. The present suggested route also revealed the remarkable optical and chemical stability of the colloidal QDs which establishes them as a decent kind of nano-scale structure for light emitting applications, especially in biological technologies. The suggested process also has the potential to be scaled-up while maintaining the emission characteristics and structural quality necessary for industrial applications in optoelectronic devices.

  15. Proton magnetic resonance study of the influence of chemical modification, mutation, quaternary state, and ligation state on dynamic stability of the heme pocket in hemoglobin as reflected in the exchange of the proximal histidyl ring labile proton

    International Nuclear Information System (INIS)

    Han, K.H.; La Mar, G.N.; Nagai, K.

    1989-01-01

    Proton nuclear magnetic resonance spectroscopy has been utilized to investigate the rates of exchange with deuterium of the proximal histidyl ring protons in a series of chemically modified and mutated forms of Hb A. Differences in rates of exchange are related to differences in the stability of the deformed or partially unfolded intermediates from which exchange with bulk solvent takes place. Each modified/mutated Hb exhibited kinetic subunit heterogeneity in the reduced ferrous state, with the alpha subunit exhibiting faster exchange than the beta subunit. Modification or mutation resulted in significant increases in the His F8 ring NH exchange rates primarily for the affected subunit and only if the modification/mutation occurs at the allosterically important alpha 1 beta 2 subunit interface. Moreover, this enhancement in exchange rate is observed primarily in that quaternary state of the modified/mutated Hb in which the modified/substituted residue makes the intersubunit contact. This confirms the importance of allosteric constraints in determining the dynamic properties of the heme pocket. Using modified or mutated Hbs that can switch between the alternate quaternary states within a given ligation state or ligate within a given quaternary state, we show that the major portion of the enhanced exchange rate in R-state oxy Hb relative to T-state deoxy Hb originates from the quaternary switch rather than from ligation. However, solely ligation effects are not negligible. The exchange rates of the His F8 ring labile protons increase dramatically upon oxidizing the iron to the ferric state, and both the subunit kinetic heterogeneity and the allosteric sensitivity to the quaternary state are essentially abolished

  16. Uranium mill tailings stabilization

    International Nuclear Information System (INIS)

    Hartley, J.N.; Koehmstedt, P.L.; Esterl, D.J.; Freeman, H.D.

    1980-02-01

    Uranium mill tailings pose a potential radiation health hazard to the public. Therefore, stabilization or disposal of these tailings in a safe and environmentally sound way is needed to minimize radon exhalation and other environmental hazards. One of the most promising concepts for stabilizing U tailings is the use of asphalt emulsion to contain radon and other hazardous materials within uranium tailings. This approach is being investigated at the Pacific Northwest Laboratory. Results of these studies indicate that a radon flux reduction of greater than 99% can be obtained using either a poured-on/sprayed-on seal (3.0 to 7.0 mm thick) or an admixture seal (2.5 to 12.7 cm thick) containing about 18 wt % residual asphalt. A field test was carried out in June 1979 at the Grand Junction tailings pile in order to demonstrate the sealing process. A reduction in radon flux ranging from 4.5 to greater than 99% (76% average) was achieved using a 15.2-cm (6-in.) admix seal with a sprayed-on top coat. A hydrostatic stabilizer was used to apply the admix. Following compaction, a spray coat seal was applied over the admix as the final step in construction of a radon seal. Overburden was applied to provide a protective soil layer over the seal. Included in part of the overburden was a herbicide to prevent root penetration

  17. Plutonium stabilization and packaging system

    International Nuclear Information System (INIS)

    1996-01-01

    This document describes the functional design of the Plutonium Stabilization and Packaging System (Pu SPS). The objective of this system is to stabilize and package plutonium metals and oxides of greater than 50% wt, as well as other selected isotopes, in accordance with the requirements of the DOE standard for safe storage of these materials for 50 years. This system will support completion of stabilization and packaging campaigns of the inventory at a number of affected sites before the year 2002. The package will be standard for all sites and will provide a minimum of two uncontaminated, organics free confinement barriers for the packaged material

  18. Greater confinement disposal program at the Savannah River Plant

    International Nuclear Information System (INIS)

    Towler, O.A.; Cook, J.R.; Peterson, D.L.; Reddick, J.A.

    1984-01-01

    A facility to demonstrate Greater Confinement Disposal (GCD) of low-level solid radioactive waste in a humid environment has been built and is operating at the Savannah River Plant (SRP). GCD practices of waste segregation into high and low activity concentrations, emplacement of waste below the root zone, waste stabilization, and capping are being used in the demonstration. Activity concentrations to select wastes for GCD are based on the volume/activity distribution of low-level solid wastes as obtained from SRP burial records, and are equal to or less than those for Class B waste in 10 CFR 61. The first disposal units constructed are twenty 9-ft-diam, 30-ft-deep boreholes. These holes will be used to dispose of wastes from the production reactors, tritiated wastes, and selected wastes from offsite. In 1984, construction will begin on an engineered GCD trench for disposal of boxed waste and large bulky items that meet the activity concentration criteria. 4 references, 5 figures, 2 tables

  19. Greater future global warming inferred from Earth's recent energy budget.

    Science.gov (United States)

    Brown, Patrick T; Caldeira, Ken

    2017-12-06

    Climate models provide the principal means of projecting global warming over the remainder of the twenty-first century but modelled estimates of warming vary by a factor of approximately two even under the same radiative forcing scenarios. Across-model relationships between currently observable attributes of the climate system and the simulated magnitude of future warming have the potential to inform projections. Here we show that robust across-model relationships exist between the global spatial patterns of several fundamental attributes of Earth's top-of-atmosphere energy budget and the magnitude of projected global warming. When we constrain the model projections with observations, we obtain greater means and narrower ranges of future global warming across the major radiative forcing scenarios, in general. In particular, we find that the observationally informed warming projection for the end of the twenty-first century for the steepest radiative forcing scenario is about 15 per cent warmer (+0.5 degrees Celsius) with a reduction of about a third in the two-standard-deviation spread (-1.2 degrees Celsius) relative to the raw model projections reported by the Intergovernmental Panel on Climate Change. Our results suggest that achieving any given global temperature stabilization target will require steeper greenhouse gas emissions reductions than previously calculated.

  20. Macroeconomic stability

    DEFF Research Database (Denmark)

    Jespersen, Jesper

    2004-01-01

    It is demonstrated that full employment and sustainable development not necessarily are conflicting goals. On the other hand macroeconomic stability cannot be obtained without a deliberate labour sharing policy and a shift in the composition of private consumption away from traditional material...

  1. Stabilized superconductors

    International Nuclear Information System (INIS)

    Wong, J.

    1975-01-01

    The stable, high field, high current composite wire comprises multiple filaments in a depleted bronze matrix, each filament comprising a type II superconducting, beta-tungsten structure, intermetallic compound layer jacketing and metallurgically bonded to a stabilizing copper core, directly or via an intermediate layer of refractory metal

  2. Chemical control in steam systems by using a stabilized inorganic product with gain of energy and speed in detecting contaminations; Controle quimico em geradores de vapor, pelo uso de agente inorganico estabilizado, com ganhos de energia e celeridade na deteccao de contaminacoes

    Energy Technology Data Exchange (ETDEWEB)

    Oliveira, Barny de; Pereira, Renato Andre Nunes [Kurita do Brasil, Rio de Janeiro, RJ (Brazil)

    2010-07-01

    This paper shows the basic conditions to control the relation between phosphate and sodium in high pressure boilers by applying a stabilized chemical product ensuring operation with low variability and energy gain by the eliminating of corrective blowdown. It presents the routine and the relevant benefits provided by a strong monitoring program of phosphate application in high pressure boilers as an important tool do detect deviations and to get better control of silica solubilization in this pressure level. (author)

  3. Atributos químicos e estabilidade de agregados sob diferentes culturas de cobertura em Latossolo do cerrado Chemical properties and aggregate stability under different cover crops in cerrado Oxisol

    Directory of Open Access Journals (Sweden)

    Glenio G. Santos

    2012-11-01

    Full Text Available Objetivou-se, com este trabalho, avaliar o efeito de diferentes culturas de cobertura sobre os atributos químicos e a estabilidade de agregados de um Latossolo do cerrado, sob plantio direto. O estudo foi conduzido em área experimental na Embrapa Arroz e Feijão, em Santo Antônio de Goiás, GO. As culturas de cobertura avaliadas foram: braquiária, milho em consórcio com braquiária (integração lavoura-pecuária, guandu anão, milheto, capim mombaça, sorgo granífero, estilosantes e crotalária. As amostras foram coletadas em abril de 2005 e 2006. O delineamento experimental foi o de blocos completos ao acaso com quatro repetições e os tratamentos arranjados em esquema fatorial 8 x 2, sendo oito culturas de cobertura e duas profundidades de amostragem do solo: 0-0,10 e 0,10-0,20 m. As culturas de cobertura influenciam, de forma diferenciada, os valores de pH e os teores de cálcio, magnésio, alumínio, fósforo, potássio, cobre, zinco e ferro do solo. O tratamento estilosantes tem maior poder em acidificar o solo. A agregação do solo varia com as culturas de cobertura e com a profundidade.The objective of this study was to evaluate the effect of different cover crops on chemical properties and aggregate stability in a cerrado Oxisol under no-tillage. The study was carried out in Embrapa Rice and Beans, in Santo Antônio de Goiás, GO, Brazil. The cover crops evaluated were: Urochloa brizantha, Urochloa brizantha and corn in association (crop-livestock integrated, Cajanus cajan, Pennisetum glaucum, Panicum maximum, Sorghum bicolor, Stylosanthes guianensis and Crotalaria juncea. The soil samples were collected in April and September 2005 and April 2006. The experimental design was in completely randomized blocks with four replications and treatments arranged in factorial scheme 8 x 2, eight cover crops and two soil sampling depths, 0-0.10 and 0.10-0.20 m. The different cover crops affect pH values and calcium, magnesium, aluminum

  4. Organochlorine chemical residues in Northern Cardinal (Cardinalis cardinalis) eggs from Greater Washington, DC USA

    Science.gov (United States)

    Schmitt, Christopher J.; Echols, Kathy R.; Peterman, Paul; Orazio, Carl; Grimm, Christiana; Tan, Shirlee; Diggs, Nora E.; Marra, Peter P.

    2018-01-01

    Northern Cardinal eggs from six neighborhoods near Washington DC were analyzed for organochlorine pesticides and PCBs. All compounds were detected more frequently and at higher concentrations in more heavily urbanized neighborhoods. DDT (mostly as p,pʹ-DDE) was detected in all neighborhoods. p,pʹ-DDT was typically 0.5‒16 ng/g (ww) in most suburban neighborhoods but was not detected (< 0.1 ng/g) in more rural areas; however, p,pʹ-DDT was 127‒1130 ng/g in eggs from two suburban Maryland nests and comprised 65.7% of total p,pʹ-DDT isomers in the most contaminated sample, indicating recent exposure to un-weathered DDT. Total chlordane (sum of 5 compounds) was 2‒70 ng/g; concentrations were greatest in older suburban neighborhoods. Total PCB (sum of detected congeners) was < 5‒21 ng/g. Congener patterns were similar in all neighborhoods and resembled those typical of weathered mixtures. Results indicate that wildlife remains exposed to low concentrations of legacy contaminants in suburban neighborhoods and that cardinal eggs can be used to monitor localized contamination.

  5. Nanoporous silica membranes with high hydrothermal stability

    DEFF Research Database (Denmark)

    Boffa, Vittorio; Magnacca, Giualiana; Yue, Yuanzheng

    to improve the stability of nanoporous silica structure. This work is a quantitative study on the impact of type and concentration of transition metal ions on the microporous structure and stability of amorphous silica-based membranes, which provides information on how to design chemical compositions...

  6. Flourescent Peptide-Stabilized Silver-Nanoclusters

    DEFF Research Database (Denmark)

    Gregersen, Simon

    to their physical and optoelectronic properties. These include great photostability, low toxicity, small size, and tunable spectral properties. Chemical stability of noble metal NCs is, however, very low, and they only exist transiently without a stabilizing scaffold. This has to date been done in solution using...

  7. Chemical denudation of the soil

    Energy Technology Data Exchange (ETDEWEB)

    Arrhenius, O

    1952-01-01

    The chemical denudation plays a greater role in our climate than the mechanical erosion. The Swedish well waters contain 3-4 times more soluble salts than those rivers which are fed by them. The chemical denudation therefore must be much greater than formerly calculated. A map shows the salt concentration of the well waters of Sweden. The amount of nitrogen accumulated per annum in a district of central Sweden seems to amount to 3-6 kg n per har.

  8. Photochemical stability of electrochromic polymers and devices

    DEFF Research Database (Denmark)

    Jensen, Jacob; Madsen, Morten Vesterager; Krebs, Frederik C

    2013-01-01

    The stability of fully printed flexible organic electrochromics based on 11 different conjugated polymers is explored from the fundamental chemical degradation level to the operational device level. The photochemical stability of the electrochromic polymers (ECPs) is studied enabling an analysis ...... based on flexible barrier substrates exhibit increased stability and are indeed viable in devices such as shading elements, light management systems, displays with low switching speed requirements and signage. © 2013 The Royal Society of Chemistry....

  9. Assessment of trace element stabilization in soil

    OpenAIRE

    Kumpiene, Jurate

    2005-01-01

    The thesis deals with the remediation of trace element contaminated soil by the chemical stabilization technique. The objective is to complement the knowledge about possibilities of applying the stabilization either (1) as an alternate soil remediation method to excavation and landfilling or (2) for a pre-treatment of contaminated soil before landfilling. The work is based on two case studies of the stabilization of 1) Cr, Cu, As, and Zn contaminated soil using metallic iron and 2) Pb and Cu ...

  10. Before Stabilization

    DEFF Research Database (Denmark)

    Plesner, Ursula; Horst, Maja

    2013-01-01

    of the communication about innovations in information and communication technology (ICT), and to contribute to an understanding of how different visions promise particular future configurations of workflows, communication processes, politics, economic models and social relations. Hereby, the paper adds...... to the literature on the relationship between ICTs and organizing, but with a distinct focus on innovation communication and distributed innovation processes taking place before ICTs are stabilized, issues which cannot be captured by studies of diffusion and adaptation of new ICTs within single organizations....

  11. CHEMICAL EVOLUTION

    Energy Technology Data Exchange (ETDEWEB)

    Calvin, Melvin

    1965-06-01

    How did life come to be on the surface of the earth? Darwin himself recognized that his basic idea of evolution by variation and natural selection must be a continuous process extending backward in time through that period in which the first living things arose and into the period of 'Chemical Evolution' which preceded it. We are approaching the examination of these events by two routes. One is to seek for evidence in the ancient rocks of the earth which were laid down prior to that time in which organisms capable of leaving their skeletons in the rocks to be fossilized were in existence. This period is sometime prior to approximately 600 million years ago. The earth is believed to have taken its present form approximately 4700 million years ago. We have found in rocks whose age is about 1000 million years certain organic molecules which are closely related to the green pigment of plants, chlorophyll. This seems to establish that green plants were already fluorishing prior to that time. We have now found in rocks of still greater age, namely, 2500 million years, the same kinds of molecules mentioned above which can be attributed to the presence of living organisms. If these molecules are as old as the rocks, we have thus shortened the time available for the generation of the complex biosynthetic sequences which give rise to these specific hydrocarbons (polyisoprenoids) to less than 2000 million years.

  12. Phase stabilities at a glance: Stability diagrams of nickel dipnictides

    International Nuclear Information System (INIS)

    Bachhuber, F.; Rothballer, J.; Weihrich, R.; Söhnel, T.

    2013-01-01

    In the course of the recent advances in chemical structure prediction, a straightforward type of diagram to evaluate phase stabilities is presented based on an expedient example. Crystal structures and energetic stabilities of dipnictides NiPn 2 (Pn = N, P, As, Sb, Bi) are systematically investigated by first principles calculations within the framework of density functional theory using the generalized gradient approximation to treat exchange and correlation. These dipnictides show remarkable polymorphism that is not yet understood systematically and offers room for the discovery of new phases. Relationships between the concerned structures including the marcasite, the pyrite, the arsenopyrite/CoSb 2 , and the NiAs 2 types are highlighted by means of common structural fragments. Electronic stabilities of experimentally known and related AB 2 structure types are presented graphically in so-called stability diagrams. Additionally, competing binary phases are taken into consideration in the diagrams to evaluate the stabilities of the title compounds with respect to decomposition. The main purpose of the stability diagrams is the introduction of an image that enables the estimation of phase stabilities at a single glance. Beyond that, some of the energetically favored structure types can be identified as potential new phases

  13. Stability of boson stars

    International Nuclear Information System (INIS)

    Gleiser, M.

    1988-01-01

    Boson stars are gravitationally bound, spherically symmetric equilibrium configurations of cold, free, or interacting complex scalar fields phi. As these equilibrium configurations naturally present local anisotropy, it is sensible to expect departures from the well-known stability criteria for fluid stars. With this in mind, I investigate the dynamical instability of boson stars against charge-conserving, small radial perturbations. Following the method developed by Chandrasekhar, a variational base for determining the eigenfrequencies of the perturbations is found. This approach allows one to find numerically an upper bound for the central density where dynamical instability occurs. As applications of the formalism, I study the stability of equilibrium configurations obtained both for the free and for the self-interacting [with V(phi) = (λ/4)chemical bondphichemical bond 4 ] massive scalar field phi. Instabilities are found to occur not for the critical central density as in fluid stars but for central densities considerably higher. The departure from the results for fluid stars is sensitive to the coupling λ; the higher the value of λ, the more the stability properties of boson stars approach those of a fluid star. These results are linked to the fractional anisotropy at the radius of the configuration

  14. Stabilization of red fruit-based smoothies by high-pressure processing. Part A. Effects on microbial growth, enzyme activity, antioxidant capacity and physical stability.

    Science.gov (United States)

    Hurtado, Adriana; Guàrdia, Maria Dolors; Picouet, Pierre; Jofré, Anna; Ros, José María; Bañón, Sancho

    2017-02-01

    Non-thermal pasteurization by high-pressure processing (HPP) is increasingly replacing thermal processing (TP) to maintain the properties of fresh fruit products. However, most of the research on HPP-fruit products only partially addresses fruit-pressure interaction, which limits its practical interest. The objective of this study was to assess the use of a mild HPP treatment to stabilize red fruit-based smoothies (microbial, enzymatic, oxidative and physical stability). HPP (350 MPa/10 °C/5 min) was slightly less effective than TP (85 °C/7 min) in inactivating microbes (mesophilic and psychrophilic bacteria, coliforms, yeasts and moulds) in smoothies kept at 4 °C for up to 28 days. The main limitation of using HPP was its low efficacy in inactivating oxidative (polyphenol oxidase and peroxidase) and hydrolytic (pectin methyl esterase) enzymes. Data on antioxidant status, colour parameters, browning index, transmittance, turbidity and viscosity confirmed that the HPP-smoothies have a greater tendency towards oxidation and clarification, which might lead to undesirable sensory and nutritional changes (see Part B). The microbial quality of smoothies was adequately controlled by mild HPP treatment without affecting their physical-chemical characteristics; however, oxidative and hydrolytic enzymes are highly pressure-resistant, which suggests that additional strategies should be used to stabilize smoothies. © 2016 Society of Chemical Industry. © 2016 Society of Chemical Industry.

  15. Insulin structure and stability.

    Science.gov (United States)

    Brange, J; Langkjoer, L

    1993-01-01

    Insulin is composed of 51 amino acids in two peptide chains (A and B) linked by two disulfide bonds. The three-dimensional structure of the insulin molecule (insulin monomer), essentially the same in solution and in solid phase, exists in two main conformations. These differ in the extent of helix in the B chain which is governed by the presence of phenol or its derivatives. In acid and neutral solutions, in concentrations relevant for pharmaceutical formulation, the insulin monomer assembles to dimers and at neutral pH, in the presence of zinc ions, further to hexamers. Many crystalline modifications of insulin have been identified but only those with the hexamer as the basic unit are utilized in preparations for therapy. The insulin hexamer forms a relatively stable unit but some flexibility remains within the individual molecules. The intrinsic flexibility at the ends of the B chain plays an important role in governing the physical and chemical stability of insulin. A variety of chemical changes of the primary structure (yielding insulin derivatives), and physical modifications of the secondary to quaternary structures (resulting in "denaturation," aggregation, and precipitation) are known to affect insulin and insulin preparations during storage and use (Fig. 8). The tendency of insulin to undergo structural transformation resulting in aggregation and formation of insoluble insulin fibrils has been one of the most intriguing and widely studied phenomena in relation to insulin stability. Although the exact mechanism of fibril formation is still obscure, it is now clear that the initial step is an exposure of certain hydrophobic residues, normally buried in the three-dimensional structure, to the surface of the insulin monomer. This requires displacement of the COOH-terminal B-chain residues from their normal position which can only be accomplished via monomerization of the insulin. Therefore, most methods stabilizing insulin against fibrillation share the

  16. Field investigation of keyblock stability

    International Nuclear Information System (INIS)

    Yow, J.L. Jr.

    1985-04-01

    Discontinuities in a rock mass can intersect an excavation surface to form discrete blocks (keyblocks) which can be unstable. This engineering problem is divided into two parts: block identification, and evaluation of block stability. One stable keyblock and thirteen fallen keyblocks were observed in field investigations at the Nevada Test Site. Nine blocks were measured in detail sufficient to allow back-analysis of their stability. Measurements included block geometry, and discontinuity roughness and compressive strength. Back-analysis correctly predicted stability or failure in all but two cases. These two exceptions involved situations that violated the stress assumptions of the stability calculations. Keyblock faces correlated well with known joint set orientations. The effect of tunnel orientation on keyblock frequency was apparent. Back-analysis of physical models successfully predicted block pullout force for two-dimensional models of unit thickness. Two-dimensional (2D) and three-dimensional (3D) analytic models for the stability of simple pyramidal keyblocks were examined. Calculated stability is greater for 3D analyses than for 2D analyses. Calculated keyblock stability increases with larger in situ stress magnitudes, larger lateral stress ratios, and larger shear strengths. Discontinuity stiffness controls block displacement more strongly than it does stability itself. Large keyblocks are less stable than small ones, and stability increases as blocks become more slender. Rock mass temperature decreases reduce the confining stress magnitudes and can lead to failure. The pattern of stresses affecting each block face explains conceptually the occurrence of pyramidal keyblocks that are truncated near their apex

  17. Stability of diphenylalanine peptide nanotubes under liquid conditions

    DEFF Research Database (Denmark)

    Andersen, Karsten Brandt; Castillo, Jaime; Hedstrom, Martin

    2011-01-01

    nanotubes are believed to be very stable both thermally and chemically. Previously, the chemical and thermal stability of self-organizing structures has been investigated after the evaporation of the solvent. However, it was recently discovered that the stability of the structures differed significantly...

  18. Chemical Peels

    Science.gov (United States)

    ... for Every Season How to Choose the Best Skin Care Products In This Section Dermatologic Surgery What is dermatologic ... for Every Season How to Choose the Best Skin Care Products Chemical Peels Uses for Chemical Peels Learn more ...

  19. Chemical Oscillations

    Indian Academy of Sciences (India)

    IMTECH),. Chandigarh. Praveen Kumar is pursuing his PhD in chemical dynamics at. Panjab University,. Chandigarh. Keywords. Chemical oscillations, autoca-. talYSis, Lotka-Volterra model, bistability, hysteresis, Briggs-. Rauscher reaction.

  20. Removal of selected emerging PPCP compounds using greater duckweed (Spirodela polyrhiza) based lab-scale free water constructed wetland.

    Science.gov (United States)

    Li, Jianan; Zhou, Qizhi; Campos, Luiza C

    2017-12-01

    Greater duckweed (Spirodela polyrhiza) based lab-scale free water constructed wetland (CW) was employed for removing four emerging pharmaceuticals and personal care products (PPCPs) (i.e. DEET, paracetamol, caffeine and triclosan). Orthogonal design was used to test the effect of light intensity, aeration, E.coli abundance and plant biomass on the target compounds. Synthetic wastewater contaminated with the target compounds at concentration of 25 μg/L was prepared, and both batch and continuous flow experiments were conducted. Up to 100% removals were achieved for paracetamol (PAR), caffeine (CAF) and tricolsan (TCS) while the highest removal for DEET was 32.2% in batch tests. Based on orthogonal Duncan analysis, high light intensity (240 μmolmm -2 s -1 ), full aeration, high plant biomass (1.00 kg/m 2 ) and high E.coli abundance (1.0 × 10 6  CFU/100 mL) favoured elimination of the PPCPs. Batch verification test achieved removals of 17.1%, 98.8%, 96.4% and 95.4% for DEET, PAR, CAF and TCS respectively. Continuous flow tests with CW only and CW followed by stabilization tank (CW-ST) were carried out. Final removals of the PPCP contaminants were 32.6%, 97.7%, 98.0% and 100% for DEET, PAR, CAF and TCS, respectively, by CW system alone, while 43.3%, 97.5%, 98.2% and 100%, respectively, were achieved by CW-ST system. By adding the ST tank, PPCP concentrations decreased significantly faster (p < 0.05) compared with continuous flow CW alone. In addition, after removing aerators during continuous flow CW experiments, the treatment systems presented good stability for the PPCP removals. CW-ST showed better chemical oxygen demand (COD) and total organic carbon (TOC) removals (89.3%, 91.2%, respectively) than CW only (79.4%, 85.2%, respectively). However, poor DEET removal (<50%) and high E.coli abundance (up to 1.7 log increase) in the final treated water indicated further treatment processes may be required. Statistical analysis showed significant correlations

  1. The Nature of Stability in Replicating Systems

    Directory of Open Access Journals (Sweden)

    Addy Pross

    2011-02-01

    Full Text Available We review the concept of dynamic kinetic stability, a type of stability associated specifically with replicating entities, and show how it differs from the well-known and established (static kinetic and thermodynamic stabilities associated with regular chemical systems. In the process we demonstrate how the concept can help bridge the conceptual chasm that continues to separate the physical and biological sciences by relating the nature of stability in the animate and inanimate worlds, and by providing additional insights into the physicochemical nature of abiogenesis.

  2. Chemical ecotoxicology

    International Nuclear Information System (INIS)

    Paasivirta, J.

    1991-01-01

    This book discusses risk assessment, chemical cycles, structure-activity relations, organohalogens, oil residues, mercury, sampling and analysis of trace chemicals, and emissions from the forestry industry. Topics include: Cycles of chemicals in the environment. Rick assessment and management, strucuture and toxicity, sampling and analysis of trace chemicals in environment, interpretation of the environmental analysis results, mercury in the environment, organohalogen compounds in the environment, emissions from forestry industry, oil residues in the environment: oil spills in the marine environment

  3. Chemical sensor

    Science.gov (United States)

    Rauh, R. David (Inventor)

    1990-01-01

    A sensor for detecting a chemical substance includes an insertion element having a structure which enables insertion of the chemical substance with a resulting change in the bulk electrical characteristics of the insertion element under conditions sufficient to permit effective insertion; the change in the bulk electrical characteristics of the insertion element is detected as an indication of the presence of the chemical substance.

  4. Stability of Pharmaceuticals in Space

    Science.gov (United States)

    Nguyen, Y-Uyen

    2009-01-01

    Stability testing is a tool used to access shelf life and effects of storage conditions for pharmaceutical formulations. Early research from the International Space Station (ISS) revealed that some medications may have degraded while in space. This potential loss of medication efficacy would be very dangerous to Crew health. The aim of this research project, Stability of Pharmacotherapeutic Compounds, is to study how the stability of pharmaceutical compounds is affected by environmental conditions in space. Four identical pharmaceutical payload kits containing medications in different dosage forms (liquid for injection, tablet, capsule, ointment and suppository) were transported to the ISS aboard a Space Shuttle. One of the four kits was stored on that Shuttle and the other three were stored on the ISS for return to Earth at various time intervals aboard a pre-designated Shuttle flight. The Pharmacotherapeutics laboratory used stability test as defined by the United States Pharmacopeia (USP), to access the degree of degradation to the Payload kit medications that may have occurred during space flight. Once these medications returned, the results of stability test performed on them were compared to those from the matching ground controls stored on Earth. Analyses of the results obtained from physical and chemical stability assessments on these payload medications will provide researchers additional tools to promote safe and efficacious medications for space exploration.

  5. Ab initio/GIAO-CCSD(T) study of structures, energies, and 13C NMR chemical shifts of C4H7(+) and C5H9(+) ions: relative stability and dynamic aspects of the cyclopropylcarbinyl vs bicyclobutonium ions.

    Science.gov (United States)

    Olah, George A; Surya Prakash, G K; Rasul, Golam

    2008-07-16

    The structures and energies of the carbocations C 4H 7 (+) and C 5H 9 (+) were calculated using the ab initio method. The (13)C NMR chemical shifts of the carbocations were calculated using the GIAO-CCSD(T) method. The pisigma-delocalized bisected cyclopropylcarbinyl cation, 1 and nonclassical bicyclobutonium ion, 2 were found to be the minima for C 4H 7 (+) at the MP2/cc-pVTZ level. At the MP4(SDTQ)/cc-pVTZ//MP2/cc-pVTZ + ZPE level the structure 2 is 0.4 kcal/mol more stable than the structure 1. The (13)C NMR chemical shifts of 1 and 2 were calculated by the GIAO-CCSD(T) method. Based on relative energies and (13)C NMR chemical shift calculations, an equilibrium involving the 1 and 2 in superacid solutions is most likely responsible for the experimentally observed (13)C NMR chemical shifts, with the latter as the predominant equilibrating species. The alpha-methylcyclopropylcarbinyl cation, 4, and nonclassical bicyclobutonium ion, 5, were found to be the minima for C 5H 9 (+) at the MP2/cc-pVTZ level. At the MP4(SDTQ)/cc-pVTZ//MP2/cc-pVTZ + ZPE level ion 5 is 5.9 kcal/mol more stable than the structure 4. The calculated (13)C NMR chemical shifts of 5 agree rather well with the experimental values of C 5H 9 (+).

  6. Meritocratic administration and democratic stability

    DEFF Research Database (Denmark)

    Cornell, Agnes; Lapuente, Victor

    2014-01-01

    , in democracies with meritocratic administrations, incumbents are credibly constrained from undertaking partial policies because their hands are tied in terms of managing the staff policy of the state apparatus. Consequently, countries with meritocratic bureaucracies have greater prospects for democratic...... stability. Empirically, we illustrate the mechanisms with two well-documented cases of democratic transitions that enshrined a politicized administration – Spain (1876–1936) and Venezuela (1958–1998) – and one transition that kept a meritocratic bureaucracy, Spain (1975–)....

  7. Technical concept for a greater-confinement-disposal test facility

    International Nuclear Information System (INIS)

    Hunter, P.H.

    1982-01-01

    Greater confinement disposal (GCO) has been defined by the National Low-Level Waste Program as the disposal of low-level waste in such a manner as to provide greater containment of radiation, reduce potential for migration or dispersion or radionuclides, and provide greater protection from inadvertent human and biological intrusions in order to protect the public health and safety. This paper discusses: the need for GCD; definition of GCD; advantages and disadvantages of GCD; relative dose impacts of GCD versus shallow land disposal; types of waste compatible with GCD; objectives of GCD borehole demonstration test; engineering and technical issues; and factors affecting performance of the greater confinement disposal facility

  8. Secular stability of rotating stars

    International Nuclear Information System (INIS)

    Imamura, J.N.; Friedman, J.L.; Durisen, R.H.

    1984-01-01

    In this work, we calculate the secular stability limits of rotating polytropes to nonaxisymmetric perturbations of low m. We consider polytropic indices ranging from 1 to 3 and several angular momentum distributions. Results are most conveniently presented in terms of the t-parameter, defined as the ratio of the rotational kinetic energy to the absolute value of the gravitational energy of the fluid. Previous work on polytropes considered only the m = 2 mode, which is unstable for values of the t-parameter greater than 0.14 +- 0.01 for the n values n = 1.5 and 3 and the angular momentum distributions tested (see Durisen and Imamura 1981). The GRR secular stability limit of the m = 2 mode for the Maclaurin spheroids (n = O) was determined by Chandrasekhar (1970). GRR stability limits of higher m modes for the Maclaurin spheroids were located approximately by Comins (1979a,b) and more precisely by Friedman (1983)

  9. Stabilizing Pentacene By Cyclopentannulation.

    Science.gov (United States)

    Bheemireddy, Sambasiva R; Ubaldo, Pamela C; Rose, Peter W; Finke, Aaron D; Zhuang, Junpeng; Wang, Lichang; Plunkett, Kyle N

    2015-12-21

    A new class of stabilized pentacene derivatives with externally fused five-membered rings are prepared by means of a key palladium-catalyzed cyclopentannulation step. The target compounds are synthesized by chemical manipulation of a partially saturated 6,13-dibromopentacene precursor that can be fully aromatized in a final step through a DDQ-mediated dehydrogenation reaction (DDQ=2,3-dichloro-5,6-dicyano-1,4-benzoquinone). The new 1,2,8,9-tetraaryldicyclopenta[fg,qr]pentacene derivatives have narrow energy gaps of circa 1.2 eV and behave as strong electron acceptors with lowest unoccupied molecular orbital energies between -3.81 and -3.90 eV. Photodegradation studies reveal the new compounds are more photostable than 6,13-bis(triisopropylsilylethynyl)pentacene (TIPS-pentacene). © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Effects of pH, temperature, and chemical structure on the stability of S-(purin-6-yl)-L-cysteine: evidence for a novel molecular rearrangement mechanism to yield N-(purin-6-yl)-L-cysteine.

    Science.gov (United States)

    Elfarra, A A; Hwang, I Y

    1996-01-01

    The stability of S-(purin-6-yl)-L-cysteine (SPC), a kidney-selective prodrug of 6-mercaptopurine and a putative metabolite of 6-chloropurine, was investigated under various pH and temperature conditions. At room temperature, the half-life (t 1/2) of SPC at either highly acidic (pH 3.6) or basic conditions (pH 9.6) was longer than at neutral or slightly acidic or basic conditions (pH 5.7-8.75). The primary degradation product, N-(purin-6-yl)-L-cysteine (NPC), was isolated using Sephadex LH-20 chromatography and characterized by 1H NMR and FAB/MS after derivatization with 2-iodoacetic acid. These results reveal novel stability requirements and implicate the cysteinyl amino group and the purinyl N-1 nitrogen in the mechanism of SPC rearrangement to NPC. Further evidence for this hypothesis was provided by the findings that the stability of SPC in phosphate buffer (pH 7.4) at 37 degrees C was similar to that of S-(guanin-6-yl)-L-cysteine, whereas S-(purin-6-yl)-N-acetyl-L-cysteine and S-(purin-6-yl)glutathione which have their cysteine amino groups blocked were much more stable than SPC. S-(Purin-6-yl)-L-homocysteine (SPHC) was also more stable than SPC, possibly because the formation of a 6-membered ring transition state as would be expected with SPHC is kinetically less favored than the formation of a 5-membered ring transition state as would be expected with SPC. These results may explain previous in vivo metabolism results of SPC and its analogs and may contribute to a better understanding of stability of structurally related cysteine S-conjugates.

  11. Data requirements of GREAT-ER: Modelling and validation using LAS in four UK catchments

    International Nuclear Information System (INIS)

    Price, Oliver R.; Munday, Dawn K.; Whelan, Mick J.; Holt, Martin S.; Fox, Katharine K.; Morris, Gerard; Young, Andrew R.

    2009-01-01

    Higher-tier environmental risk assessments on 'down-the-drain' chemicals in river networks can be conducted using models such as GREAT-ER (Geography-referenced Regional Exposure Assessment Tool for European Rivers). It is important these models are evaluated and their sensitivities to input variables understood. This study had two primary objectives: evaluate GREAT-ER model performance, comparing simulated modelled predictions for LAS (linear alkylbenzene sulphonate) with measured concentrations, for four rivers in the UK, and investigate model sensitivity to input variables. We demonstrate that the GREAT-ER model is very sensitive to variability in river discharges. However it is insensitive to the form of distributions used to describe chemical usage and removal rate in sewage treatment plants (STPs). It is concluded that more effort should be directed towards improving empirical estimates of effluent load and reducing uncertainty associated with usage and removal rates in STPs. Simulations could be improved by incorporating the effect of river depth on dissipation rates. - Validation of GREAT-ER.

  12. Data requirements of GREAT-ER: Modelling and validation using LAS in four UK catchments

    Energy Technology Data Exchange (ETDEWEB)

    Price, Oliver R., E-mail: oliver.price@unilever.co [Safety and Environmental Assurance Centre, Unilever, Colworth Science Park, Sharnbrook, Bedfordshire MK44 1LQ (United Kingdom); Munday, Dawn K. [Safety and Environmental Assurance Centre, Unilever, Colworth Science Park, Sharnbrook, Bedfordshire MK44 1LQ (United Kingdom); Whelan, Mick J. [Department of Natural Resources, School of Applied Sciences, Cranfield University, College Road, Cranfield, Bedfordshire MK43 0AL (United Kingdom); Holt, Martin S. [ECETOC, Ave van Nieuwenhuyse 4, Box 6, B-1160 Brussels (Belgium); Fox, Katharine K. [85 Park Road West, Birkenhead, Merseyside CH43 8SQ (United Kingdom); Morris, Gerard [Environment Agency, Phoenix House, Global Avenue, Leeds LS11 8PG (United Kingdom); Young, Andrew R. [Wallingford HydroSolutions Ltd, Maclean building, Crowmarsh Gifford, Wallingford, Oxon OX10 8BB (United Kingdom)

    2009-10-15

    Higher-tier environmental risk assessments on 'down-the-drain' chemicals in river networks can be conducted using models such as GREAT-ER (Geography-referenced Regional Exposure Assessment Tool for European Rivers). It is important these models are evaluated and their sensitivities to input variables understood. This study had two primary objectives: evaluate GREAT-ER model performance, comparing simulated modelled predictions for LAS (linear alkylbenzene sulphonate) with measured concentrations, for four rivers in the UK, and investigate model sensitivity to input variables. We demonstrate that the GREAT-ER model is very sensitive to variability in river discharges. However it is insensitive to the form of distributions used to describe chemical usage and removal rate in sewage treatment plants (STPs). It is concluded that more effort should be directed towards improving empirical estimates of effluent load and reducing uncertainty associated with usage and removal rates in STPs. Simulations could be improved by incorporating the effect of river depth on dissipation rates. - Validation of GREAT-ER.

  13. Assessing Human Impacts on the Greater Akaki River, Ethiopia ...

    African Journals Online (AJOL)

    We assessed the impacts of human activities on the Greater Akaki River using physicochemical parameters and macroinvertebrate metrics. Physicochemical samples and macroinvertebrates were collected bimonthly from eight sites established on the Greater Akaki River from February 2006 to April 2006. Eleven metrics ...

  14. Comparative Education in Greater China: Contexts, Characteristics, Contrasts and Contributions.

    Science.gov (United States)

    Bray, Mark; Qin, Gui

    2001-01-01

    The evolution of comparative education in Greater China (mainland China, Taiwan, Hong Kong, and Macau) has been influenced by size, culture, political ideologies, standard of living, and colonialism. Similarities and differences in conceptions of comparative education are identified among the four components and between Greater China and other…

  15. Greater temperature sensitivity of plant phenology at colder sites

    DEFF Research Database (Denmark)

    Prevey, Janet; Vellend, Mark; Ruger, Nadja

    2017-01-01

    Warmer temperatures are accelerating the phenology of organisms around the world. Temperature sensitivity of phenology might be greater in colder, higher latitude sites than in warmer regions, in part because small changes in temperature constitute greater relative changes in thermal balance...

  16. Breeding of Greater and Lesser Flamingos at Sua Pan, Botswana ...

    African Journals Online (AJOL)

    to fledging was unknown owing to the rapid drying of the pan in late March 1999. No Greater Flamingo breeding was seen that season. Exceptional flooding during 1999–2000 produced highly favourable breeding conditions, with numbers of Greater and Lesser Flamingos breeding estimated to be 23 869 and 64 287 pairs, ...

  17. Surgical anatomy of greater occipital nerve and its relation to ...

    African Journals Online (AJOL)

    Introduction: The knowledge of the anatomy of greater occipital nerve and its relation to occipital artery is important for the surgeon. Blockage or surgical release of greater occipital nerve is clinically effective in reducing or eliminating chronic migraine symptoms. Aim: The aim of this research was to study the anatomy of ...

  18. Surgical anatomy of greater occipital nerve and its relation to ...

    African Journals Online (AJOL)

    Nancy Mohamed El Sekily

    2014-08-19

    Aug 19, 2014 ... Abstract Introduction: The knowledge of the anatomy of greater occipital nerve and its relation to occipital artery is important for the surgeon. Blockage or surgical release of greater occipital nerve is clinically effective in reducing or eliminating chronic migraine symptoms. Aim: The aim of this research was to ...

  19. INDUSTRIAL LAND DEVELOPMENT AND MANUFACTURING DECONCENTRATION IN GREATER JAKARTA

    NARCIS (Netherlands)

    Hudalah, Delik; Viantari, Dimitra; Firman, Tommy; Woltjer, Johan

    2013-01-01

    Industrial land development has become a key feature of urbanization in Greater Jakarta, one of the largest metropolitan areas in Southeast Asia. Following Suharto's market-oriented policy measures in the late 1980s, private developers have dominated the land development projects in Greater Jakarta.

  20. Strategies for Talent Management: Greater Philadelphia Companies in Action

    Science.gov (United States)

    Council for Adult and Experiential Learning (NJ1), 2008

    2008-01-01

    Human capital is one of the critical issues that impacts the Greater Philadelphia region's ability to grow and prosper. The CEO Council for Growth (CEO Council) is committed to ensuring a steady and talented supply of quality workers for this region. "Strategies for Talent Management: Greater Philadelphia Companies in Action" provides…

  1. Industrial Wastes as Auxiliary Additives to Cement/Lime Stabilization of Soils

    OpenAIRE

    James, Jijo; Pandian, P. Kasinatha

    2016-01-01

    Chemical stabilization involves the use of chemical agents for initiating reactions within the soil for modification of its geotechnical properties. Cement and lime stabilization have been the most common stabilization methods adopted for soil treatment. Cement stabilization results in good compressive strengths and is preferred for cohesionless to moderately cohesive soil but loses effectiveness when the soil is highly plastic. Lime stabilization is the most preferred method for plastic clay...

  2. Nanoporous-carbon adsorbers for chemical microsensors.

    Energy Technology Data Exchange (ETDEWEB)

    Overmyer, Donald L.; Siegal, Michael P.; Staton, Alan W.; Provencio, Paula Polyak; Yelton, William Graham

    2004-11-01

    Chemical microsensors rely on partitioning of airborne chemicals into films to collect and measure trace quantities of hazardous vapors. Polymer sensor coatings used today are typically slow to respond and difficult to apply reproducibly. The objective of this project was to produce a durable sensor coating material based on graphitic nanoporous-carbon (NPC), a new material first studied at Sandia, for collection and detection of volatile organic compounds (VOC), toxic industrial chemicals (TIC), chemical warfare agents (CWA) and nuclear processing precursors (NPP). Preliminary studies using NPC films on exploratory surface-acoustic-wave (SAW) devices and as a {micro}ChemLab membrane preconcentrator suggested that NPC may outperform existing, irreproducible coatings for SAW sensor and {micro}ChemLab preconcentrator applications. Success of this project will provide a strategic advantage to the development of a robust, manufacturable, highly-sensitive chemical microsensor for public health, industrial, and national security needs. We use pulsed-laser deposition to grow NPC films at room-temperature with negligible residual stress, and hence, can be deposited onto nearly any substrate material to any thickness. Controlled deposition yields reproducible NPC density, morphology, and porosity, without any discernable variation in surface chemistry. NPC coatings > 20 {micro}m thick with density < 5% that of graphite have been demonstrated. NPC can be 'doped' with nearly any metal during growth to provide further enhancements in analyte detection and selectivity. Optimized NPC-coated SAW devices were compared directly to commonly-used polymer coated SAWs for sensitivity to a variety of VOC, TIC, CWA and NPP. In every analyte, NPC outperforms each polymer coating by multiple orders-of-magnitude in detection sensitivity, with improvements ranging from 103 to 108 times greater detection sensitivity! NPC-coated SAW sensors appear capable of detecting most analytes

  3. [Chemical weapons and chemical terrorism].

    Science.gov (United States)

    Nakamura, Katsumi

    2005-10-01

    Chemical Weapons are kind of Weapons of Mass Destruction (WMD). They were used large quantities in WWI. Historically, large quantities usage like WWI was not recorded, but small usage has appeared now and then. Chemical weapons are so called "Nuclear weapon for poor countrys" because it's very easy to produce/possession being possible. They are categorized (1) Nerve Agents, (2) Blister Agents, (3) Cyanide (blood) Agents, (4) Pulmonary Agents, (5) Incapacitating Agents (6) Tear Agents from the viewpoint of human body interaction. In 1997 the Chemical Weapons Convention has taken effect. It prohibits chemical weapons development/production, and Organization for the Prohibition of Chemical Weapons (OPCW) verification regime contributes to the chemical weapons disposal. But possibility of possession/use of weapons of mass destruction by terrorist group represented in one by Matsumoto and Tokyo Subway Sarin Attack, So new chemical terrorism countermeasures are necessary.

  4. Hazardous Chemicals

    Centers for Disease Control (CDC) Podcasts

    Chemicals are a part of our daily lives, providing many products and modern conveniences. With more than three decades of experience, The Centers for Disease Control and Prevention (CDC) has been in the forefront of efforts to protect and assess people's exposure to environmental and hazardous chemicals. This report provides information about hazardous chemicals and useful tips on how to protect you and your family from harmful exposure.

  5. Alarms, Chemical

    Science.gov (United States)

    cited in applicable qualitative materiel requirements, small development requirements, technical characteristics, and other requirements and documentation that pertain to automatic chemical agent alarms.

  6. Chemical oceanography

    National Research Council Canada - National Science Library

    Millero, F.J

    1996-01-01

    Chemical Oceanography presents a comprehensive examination of the chemistry of oceans through discussions of such topics as descriptive physical oceanography, the composition of seawater and the major...

  7. Electrochemical stabilization of clayey ground

    Science.gov (United States)

    Rzhanitzin, B.A.; Sokoloff, V.P.

    1947-01-01

    Recently developed new methods of stabilization of weak grounds (e.g. the silicate treatment) are based on injection of chemical solutions into the ground. Such methods are applicable accordingly only to the kinds of ground that have the coefficient of filtration higher than 2 meters per 24 hours and permit penetration of the chemical solutions under pressure. This limit, however, as it is shown by our experience in construction, excludes a numerous and an important class of grounds, stabilization of which is indispensable in many instances. For example, digging of trenches and pits in clayey, silty, or sandy ground shows that all these types act like typical "floaters" (sluds? -S) in the presence of the ground water pressure. There were several instances in the canalization of the city of Moskow where the laying of trenches below the ground water level has led to extreme difficulties with clayey and silty ground. Similar examples could be cited in mining, engineering hydrology, and railroad construction. For these reasons, the development of methods of stabilizing such difficult types of ground has become an urgent problem of our day. In 1936, the author began his investigations, at the ground Stabilization Laboratory of VODGEO Institute, with direct electrical current as the means of stabilization of grounds. Experiments had shown that a large number of clayey types, following passage of direct electrical current, undergoes a transformation of its physico-chemical properties. It was established that the (apparent -S) density of the ground is substantially increased in consequence of the application of direct electrical current. The ground loses also its capacity to swell and to soften in water. Later, after a more detailed study of the physico-chemical mechanism of the electrical stabilization, it became possible to develop the method so as to make it applicable to sandy and silty as well as to clayey ground. By this time (1941, S.), the method has already been

  8. Effect of Rice Husk Ash on Soil Stabilization

    OpenAIRE

    Muhammad Qasim; Aroj Bashir; Mubashar Tanvir; Malik Muhammad Anees

    2015-01-01

    The soil frequently is fragile and has low stability in heavy loading. The objective of this study is to review the stabilization of soil using sustainable methods. Some strengthening approaches are available for stabilization of expansive soils. These methods consist of stabilization with soil replacement, chemical additives, moisture control, rewetting, surcharge loading, compaction control and thermal methods. The disadvantages may be associated with all these methods due to ineffectivenes...

  9. Fractures of the greater trochanter following total hip replacement.

    Science.gov (United States)

    Brun, Ole-Christian L; Maansson, Lukas

    2013-01-01

    We studied the incidence of greater trochanteric fractures at our department following THR. In all we examined 911 patients retrospectively and found the occurance of a greater trochanteric fracture to be 3%. Patients with fractures had significantly poorer outcome on Oxford Hip score, Pain VAS, Satisfaction VAS and EQ-5D compared to THR without fractures. Greater trochanteric fracture following THR is one of the most common complications following THR. It has previously been thought to have little impact on the overall outcome following THR, but our study suggests otherwise.

  10. Pd/CeO2/SiC Chemical Sensors

    Science.gov (United States)

    Lu, Weijie; Collins, W. Eugene

    2005-01-01

    The incorporation of nanostructured interfacial layers of CeO2 has been proposed to enhance the performances of Pd/SiC Schottky diodes used to sense hydrogen and hydrocarbons at high temperatures. If successful, this development could prove beneficial in numerous applications in which there are requirements to sense hydrogen and hydrocarbons at high temperatures: examples include monitoring of exhaust gases from engines and detecting fires. Sensitivity and thermal stability are major considerations affecting the development of high-temperature chemical sensors. In the case of a metal/SiC Schottky diode for a number of metals, the SiC becomes more chemically active in the presence of the thin metal film on the SiC surface at high temperature. This increase in chemical reactivity causes changes in chemical composition and structure of the metal/SiC interface. The practical effect of the changes is to alter the electronic and other properties of the device in such a manner as to degrade its performance as a chemical sensor. To delay or prevent these changes, it is necessary to limit operation to a temperature sensor structures. The present proposal to incorporate interfacial CeO2 films is based partly on the observation that nanostructured materials in general have potentially useful electrical properties, including an ability to enhance the transfer of electrons. In particular, nanostructured CeO2, that is CeO2 with nanosized grains, has shown promise for incorporation into hightemperature electronic devices. Nanostructured CeO2 films can be formed on SiC and have been shown to exhibit high thermal stability on SiC, characterized by the ability to withstand temperatures somewhat greater than 700 C for limited times. The exchanges of oxygen between CeO2 and SiC prevent the formation of carbon and other chemical species that are unfavorable for operation of a SiC-based Schottky diode as a chemical sensor. Consequently, it is anticipated that in a Pd/CeO2/SiC Schottky

  11. Chemical stability of La0.6Sr0.4CoO3−δ in oxygen permeation applications under exposure to N2 and CO2

    DEFF Research Database (Denmark)

    Esposito, Vincenzo; Søgaard, Martin; Hendriksen, Peter Vang

    2012-01-01

    Phase stability and chemical reactivity of (La0.6Sr0.4)0.99CoO3−δ (LSC64) was tested in oxidative (pO2= 0.21 atm) and slightly reducing conditions (pO2~10−5 atm), as well as in carbon dioxide (pO2~10−4 atm) to evaluate the material performance for oxygen separation technologies. Thin film LSC64 o...... and chemical history of the samples. A flux of 4–6 Nml min−1 cm−2 in the temperature range of 800–900 °C was demonstrated for optimized membranes and conditions. © 2012 Elsevier B.V. All rights reserved.......Phase stability and chemical reactivity of (La0.6Sr0.4)0.99CoO3−δ (LSC64) was tested in oxidative (pO2= 0.21 atm) and slightly reducing conditions (pO2~10−5 atm), as well as in carbon dioxide (pO2~10−4 atm) to evaluate the material performance for oxygen separation technologies. Thin film LSC64...... measurements in air, N2 and CO2. Under mild reduction LSC64 partly decomposes to a K2NiF4-type phase (i.e. (La,Sr)2CoO4), and Co-oxide, and under high pCO2 forms SrCO3. The latter is found to impair membrane performance. Electrical properties and oxygen permeation (jO2) in thin membranes depend on the thermal...

  12. Stability constants of scandium complexes, 1

    International Nuclear Information System (INIS)

    Itoh, Hisako; Itoh, Naomi; Suzuki, Yasuo

    1984-01-01

    The stability constants of scandium complexes with some carboxylate ligands were determined potentiometrically at 25.0 and 40.0 0 C and at an ionic strength of 0.10 with potassium nitrate as supporting electrolyte. The constants of the scandium complexes were appreciably greater than those of the corresponding lanthanoid complexes, as expected. The changes in free energy, enthalpy, and entropy for the formation of the scandium complexes were calculated from the stability constants at two temperatures. (author)

  13. Prey selection by a reintroduced lion population in the Greater ...

    African Journals Online (AJOL)

    Prey selection by a reintroduced lion population in the Greater Makalali Conservancy, South Africa. Dave Druce, Heleen Genis, Jonathan Braak, Sophie Greatwood, Audrey Delsink, Ross Kettles, Luke Hunter, Rob Slotow ...

  14. LiveDiverse: Case study area, Greater Kruger South Africa

    CSIR Research Space (South Africa)

    Nortje, Karen

    2011-01-01

    Full Text Available Livelihoods and Biodiversity in Developing Countries Case study area: Greater Kruger, South Africa January 2011 Kolhapur, India Where are we? HARDSHIP LIVELIHOODS NATURE & BIODIVERSITY BELIEFS & CULTURAL PRACTISE threesansinv foursansinv onesansinv...

  15. Exploration of the Energy Efficiency of the Greater London Authority ...

    African Journals Online (AJOL)

    GLA Building/City Hall) ... Journal Home > Vol 11, No 2 (2007) > ... The Greater London Authority building was acclaimed as being energy efficient, with claims of 75 % reduction in its annual energy consumption compared to a high specification ...

  16. Molecular insights into the biology of Greater Sage-Grouse

    Science.gov (United States)

    Oyler-McCance, Sara J.; Quinn, Thomas W.

    2011-01-01

    Recent research on Greater Sage-Grouse (Centrocercus urophasianus) genetics has revealed some important findings. First, multiple paternity in broods is more prevalent than previously thought, and leks do not comprise kin groups. Second, the Greater Sage-Grouse is genetically distinct from the congeneric Gunnison sage-grouse (C. minimus). Third, the Lyon-Mono population in the Mono Basin, spanning the border between Nevada and California, has unique genetic characteristics. Fourth, the previous delineation of western (C. u. phaios) and eastern Greater Sage-Grouse (C. u. urophasianus) is not supported genetically. Fifth, two isolated populations in Washington show indications that genetic diversity has been lost due to population declines and isolation. This chapter examines the use of molecular genetics to understand the biology of Greater Sage-Grouse for the conservation and management of this species and put it into the context of avian ecology based on selected molecular studies.

  17. Greater saphenous vein anomaly and aneurysm with subsequent pulmonary embolism

    OpenAIRE

    Ma, Truong; Kornbau, Craig

    2017-01-01

    Abstract Venous aneurysms often present as painful masses. They can present either in the deep or superficial venous system. Deep venous system aneurysms have a greater risk of thromboembolism. Though rare, there have been case reports of superficial aneurysms and thrombus causing significant morbidity such as pulmonary embolism. We present a case of an anomalous greater saphenous vein connection with an aneurysm and thrombus resulting in a pulmonary embolism. This is the only reported case o...

  18. GREATER OMENTUM: MORPHOFUNCTIONAL CHARACTERISTICS AND CLINICAL SIGNIFICANCE IN PEDIATRICS

    Directory of Open Access Journals (Sweden)

    A.V. Nekrutov

    2007-01-01

    Full Text Available The review analyzes the structure organization and pathophysiological age specificities of the greater omentum, which determine its uniqueness and functional diversity in a child's organism. the article discusses protective functions of the organ, its role in the development of post operative complications of children, and the usage in children's reconstructive plastic surgery.Key words: greater omentum, omentitis, of post operative complications, children.

  19. Socio-economic considerations of cleaning Greater Vancouver's air

    International Nuclear Information System (INIS)

    2005-08-01

    Socio-economic considerations of better air quality on the Greater Vancouver population and economy were discussed. The purpose of the study was to provide socio-economic information to staff and stakeholders of the Greater Vancouver Regional District (GVRD) who are participating in an Air Quality Management Plan (AQMP) development process and the Sustainable Region Initiative (SRI) process. The study incorporated the following methodologies: identification and review of Canadian, American, and European quantitative socio-economic, cost-benefit, cost effectiveness, competitiveness and health analyses of changes in air quality and measures to improve air quality; interviews with industry representatives in Greater Vancouver on competitiveness impacts of air quality changes and ways to improve air quality; and a qualitative analysis and discussion of secondary quantitative information that identifies and evaluates socio-economic impacts arising from changes in Greater Vancouver air quality. The study concluded that for the Greater Vancouver area, the qualitative analysis of an improvement in Greater Vancouver air quality shows positive socio-economic outcomes, as high positive economic efficiency impacts are expected along with good social quality of life impacts. 149 refs., 30 tabs., 6 appendices

  20. Journal of Chemical Sciences | Indian Academy of Sciences

    Indian Academy of Sciences (India)

    DFT global chemical reactivity descriptors (chemical hardness, total energy, electronic chemical potential, and electrophilicity) are calculated for the isomers and used to predict their relative stability and reactivity. The chemical reactivity indices are found to be related to the bond angle defined by the cis carbonyls and the ...