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Sample records for solution ph levels

  1. Chemical Speciation and Bond Lengths of Organic Solutes by Core-Level Spectroscopy: pH and Solvent Influence on p-Aminobenzoic Acid.

    Science.gov (United States)

    Stevens, Joanna S; Gainar, Adrian; Suljoti, Edlira; Xiao, Jie; Golnak, Ronny; Aziz, Emad F; Schroeder, Sven L M

    2015-05-04

    Through X-ray absorption and emission spectroscopies, the chemical, electronic and structural properties of organic species in solution can be observed. Near-edge X-ray absorption fine structure (NEXAFS) and resonant inelastic X-ray scattering (RIXS) measurements at the nitrogen K-edge of para-aminobenzoic acid reveal both pH- and solvent-dependent variations in the ionisation potential (IP), 1s→π* resonances and HOMO-LUMO gap. These changes unequivocally identify the chemical species (neutral, cationic or anionic) present in solution. It is shown how this incisive chemical state sensitivity is further enhanced by the possibility of quantitative bond length determination, based on the analysis of chemical shifts in IPs and σ* shape resonances in the NEXAFS spectra. This provides experimental access to detecting even minor variations in the molecular structure of solutes in solution, thereby providing an avenue to examining computational predictions of solute properties and solute-solvent interactions. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. Effect of pH Upper Control Limit on Nutrient Solution Component and Water Spinach Growth under Hydroponics

    OpenAIRE

    Xuzhang Xue; Yinkun Li; Feng Li; Fang Zhang; Wenzhong Guo

    2015-01-01

    In this study, experiment with four levels of nutrient solution pH control upper limit was conducted to explore the optimal nutrient solution pH management scheme under hydroponics by evaluating the nutrient solution characters i.e., pH, Electric Conductivity (EC), nitrate, soluble phosphorus (soluble-P), water spinach growth and quality. The results showed that the nutrient solution pH was 8.2 and unsuitable for water spinach growth under the treatment with no pH regulation during the experi...

  3. Corrosion studies of thermally sensitised AGR fuel element brace in pH7 and pH9.2 borate solutions

    International Nuclear Information System (INIS)

    Tyfield, S.P.; Smith, C.A.

    1987-04-01

    Brace and cladding of AGR fuel elements sensitised in reactor are susceptible to intergranular and crevice corrosion, which may initiate in the pH7 borate pond storage environment of CEGB/SSEB stations. This report considers the benefit in corrosion control that is provided by raising the pond solution pH to 9.2, whilst maintaining the boron level at 1250 gm -3 . The greater corrosion protection provided by pH9.2 solution compared to the pH7 borate solution is demonstrated by a series of tests with non-active laboratory sensitised brace samples exposed to solutions dosed with chloride or sulphate in order to promote localised corrosion. The corrosion tests undertaken consisted of 5000 hour immersions at 32 0 C and shorter term electrochemically monitored experiments (rest potential, impedance, anodic current) generally conducted at 22 0 C. The pH9.2 solution effectively inhibited the initiation of crevice and intergranular corrosion in the presence of low levels of chloride and sulphate, whereas the pH7 solution did not always do so. However, the pH9.2 solution, dosed with 40 gm -3 chloride, failed to suppress fully crevice corrosion initiated in unborated 40 gm -3 chloride solution at 22 0 C. Fluoride is not deleterious at low levels ∼ 10 gm -3 in the borate solutions. The significant improvement in corrosion control demonstrated for the change from pH7 to pH9.2 borate solution on laboratory sensitised brace samples should ideally be confirmed using complete irradiated AGR fuel elements. (U.K.)

  4. Effect of nitrogen form and pH of nutrient solution on the changes in pH and EC of spinach rhizosphere in hydroponic culture

    OpenAIRE

    M. Parsazadeh; N. Najafi

    2011-01-01

    In this study, the effect of nitrate to ammonium ratio and pH of nutrient solution on the changes in pH and EC of rhizosphere during spinach growth period in perlite culture, under greenhouse conditions, was investigated. A split factorial experiment in a completely randomized design with four replications was conducted with three factors including nutrient solution’s pH in three levels (4.5, 6.5 and 8), nitrate to ammonium ratio of nutrient solution in five levels (100:0, 75:25, 50:50, 25:75...

  5. A Busy period analysis of the level dependent PH/PH/1/K queue

    NARCIS (Netherlands)

    Al Hanbali, Ahmad

    2011-01-01

    In this paper, we study the transient behavior of a level dependent single server queuing system with a waiting room of finite size during the busy period. The focus is on the level dependent PH/PH/1/K queue. We derive in closed form the joint transform of the length of the busy period, the number

  6. Automated pH Control of Nutrient Solution in a Hydroponic Plant Growth System

    Science.gov (United States)

    Smith, B.; Dogan, N.; Aglan, H.; Mortley, D.; Loretan, P.

    1998-01-01

    Over, the years, NASA has played an important role in providing to and the development of automated nutrient delivery and monitoring, systems for growing crops hydroponically for long term space missions. One example are the systems used in the Biomass Production Chamber (BPC) at Kennedy Space Center (KSC). The current KSC monitoring system is based on an engineering workstation using standard analog/digital input/output hardware and custom written software. The monitoring system uses completely separate sensors to provide a check of control sensor accuracy and has the ability to graphically display and store data form past experiment so that they are available for data analysis [Fortson, 1992]. In many cases, growing systems have not been fitted with the kind of automated control systems as used at KSC. The Center for Food and Environmental Systems for Human Exploration of Space (CFESH) located on the campus of Tuskegee University, has effectively grown sweetpotatoes and peanuts hydroponically for the past five years. However they have adjusted the pH electrical conductivity and volume of the hydroponic nutrient solution only manually at times when the solution was to be replenished or changed out according to its protocol (e.g. one-week, two-week, or two-day cycle). But the pH of the nutrient solution flowing through the channel is neither known nor controlled between the update, change out, or replenishment period. Thus, the pH of the nutrient solution is not held at an optimum level over the span of the plant's growth cycle. To solve this dilemma, an automated system for the control and data logging of pH data relative to sweetpotato production using the nutrient film technique (NFT) has been developed, This paper discusses a microprocessor-based system, which was designed to monitor, control, and record the pH of a nutrient solution used for growing sweetpotatoes using NFT.

  7. Effect of Nutrition Solution pH and Electrical Conductivity on Fusarium Wilt on Strawberry Plants in Hydroponic Culture

    Directory of Open Access Journals (Sweden)

    Myeong Hyeon Nam

    2018-03-01

    Full Text Available Fusarium wilt on strawberry plants caused by Fusarium oxysporum f. sp. fragariae (Fof is a major disease in Korea. The prevalence of this disease is increasing, especially in hydroponic cultivation in strawberry field. This study assessed the effect of nutrition solution pH and electrical conductivity (EC on Fusarium wilt in vitro and in field trials. pH levels of 5.0, 5.5, 6.0, 6.5, 7.0, and 7.5 were assayed in vitro and in field trials. EC levels at 0, 0.5, 0.8, 1.0, and 1.5 dS∙m⁻¹ were assayed in field trials. Mycelial growth of Fof increased with increasing pH and was highest at 25°C pH 7 and lowest at 20°C, pH 5.0 in vitro. The incidence of Fusarium wilt was lowest in the pH 6.5 treatment and highest in the pH 5 treatment in field trials. At higher pH levels, the EC decreased in the drain solution and the potassium content of strawberry leaves increased. In the EC assay, the severity of Fusarium wilt and nitrogen content of leaves increased as the EC increased. These results indicate that Fusarium wilt is related to pH and EC in hydroponic culture of strawberry plants.

  8. The effect of pH on phosphorus availability and speciation in an aquaponics nutrient solution.

    Science.gov (United States)

    Cerozi, Brunno da Silva; Fitzsimmons, Kevin

    2016-11-01

    The interaction between the main ions in aquaponics nutrient solutions affects chemical composition and availability of nutrients, and nutrient uptake by plant roots. This study determined the effect of pH on phosphorus (P) speciation and availability in an aquaponics nutrient solution and used Visual MINTEQ to simulate P species and P activity. In both experimental and simulated results, P availability decreased with increase in pH of aquaponics nutrient solutions. According to simulations, P binds to several cations leaving less free phosphate ions available in solution. High pH values resulted in the formation of insoluble calcium phosphate species. The study also demonstrated the importance of organic matter and alkalinity in keeping free phosphate ions in solution at high pH ranges. It is recommended though that pH in aquaponics systems is maintained at a 5.5-7.2 range for optimal availability and uptake by plants. Copyright © 2016 Elsevier Ltd. All rights reserved.

  9. Effect of pH value of applied solution on radioiodine sorption by soils

    International Nuclear Information System (INIS)

    Szabova, T.

    1976-01-01

    Sorption of radioiodine by soils was followed under static conditions at different pH values of the initial solution in five soil types. Sorption of radioiodine by soils is affected by the amount of the organic mass and by the pH of solutions. With the same pH, soils containing a higher amount of the organic mass absorb more radioiodine. The highest sorption percentage of 131 I - for all pH values was found in meadow chernozem soil and the lowest in the rendzina and in carboniferous meadow soils. The highest sorption of 131 I - for degraded chernozem, meadow chernozem soils and brown soil was recorded at pH 5 and for carboniferous meadow soil and rendzina at pH 7. (author)

  10. Computer model of hydroponics nutrient solution pH control using ammonium.

    Science.gov (United States)

    Pitts, M; Stutte, G

    1999-01-01

    A computer simulation of a hydroponics-based plant growth chamber using ammonium to control pH was constructed to determine the feasibility of such a system. In nitrate-based recirculating hydroponics systems, the pH will increase as plants release hydroxide ions into the nutrient solution to maintain plant charge balance. Ammonium is an attractive alternative to traditional pH controls in an ALSS, but requires careful monitoring and control to avoid overdosing the plants with ammonium. The primary advantage of using NH4+ for pH control is that it exploits the existing plant nutrient uptake charge balance mechanisms to maintain solution pH. The simulation models growth, nitrogen uptake, and pH of a l-m2 stand of wheat. Simulation results indicated that ammonium-based control of nutrient solution pH is feasible using a proportional integral controller. Use of a 1 mmol/L buffer (Ka = 1.6 x 10(-6)) in the nutrient solution is required.

  11. Considerations on prevention of phlebitis and venous pain from intravenous prostaglandin E(1) administration by adjusting solution pH: in vitro manipulations affecting pH.

    Science.gov (United States)

    Kohno, Emiko; Nishikata, Mayumi; Okamura, Noboru; Matsuyama, Kenji

    2008-01-01

    Prostaglandin E(1) (PGE(1); Alprostadil Alfadex) is a potent vasodilator and inhibitor of platelet aggregation used to treat patients with peripheral vascular disease. The main adverse effects of intravenous PGE(1) administration, phlebitis and venous pain, arise from the unphysiologically low pH of infusion solutions. When PGE(1) infusion solutions with a pH value greater then 6 are used, phlebitis and venous pain are considered to be avoidable. Beginning with a PGE(1) infusion solution with pH greater than 6, we add the amount of 7% sodium bicarbonate needed to bring the solution to pH 7.4 if phlebitis or venous pain develops. In the present study we established a convenient nomogram showing the relationship between the titratable acidity of various infusion solutions and the volume of 7% sodium bicarbonate required to attain pH 7.4 for preventing the phlebitis and venous pain associated with PGE(1) infusion.

  12. Metal extraction from Cetraria islandica (L. Ach. lichen using low pH solutions

    Directory of Open Access Journals (Sweden)

    ANA A. CUCULOVIC

    2008-04-01

    Full Text Available Extraction of metals (K, Al, Ca, Mg, Fe, Cu, Ba, Zn, Mn and Sr from dry Cetraria islandica (L. Ach. lichen was performed using solutions similar to acid rain (solution A – H2SO4–HNO3–(NH42SO4 and solution B – H2SO4–HNO3–(NH42SO4–NH4NO3. The pH values of these solutions were 2.00, 2.58, 2.87, 3.28, and 3.75. Five consecutive extractions were performed with each solution. In all solutions, the extracted metal content, except Cu and Ca, was the highest in the first extract. The highest percentage of the metals desorbed in the first extraction was obtained using solutions with low pH values, 2.00, 2.58, and 2.87. The lowest percentage in the first extraction was obtained using solutions with pH 3.28 and 3.75, indicating influence of the H+ ion on the extraction. According to the results obtained, the investigated metals form two groups. The first group includes K, Al, Ca, Mg, and Fe. They were extracted in each of the five extractions at each of the pH values. The second group includes Ba, Zn, Mn, Cu, and Sr, which were not all extracted at each pH value. The first group yielded three types of extraction curves when the logarithms of extracted metal amounts were plotted as a function of the number of successive extractions. These effects indicate that three different positions (centres of metal ion accumulation exist in the lichen (due to sorption, complex formation, or other processes present in the tissues.

  13. Influence of pH of spray solution on optoelectronic properties of cadmium oxide thin films

    International Nuclear Information System (INIS)

    Hodlur, R. M.; Rabinal, M. K.

    2015-01-01

    Highly conducting transparent cadmium oxide thin films were prepared by the conventional spray pyrolysis technique. The pH of the spray solution is varied by adding ammonia/hydrochloric acid. The effect of pH on the morphology, crystallinity and optoelectronic properties of these films is studied. The structural analysis showed all the films in the cubic phase. For the films with pH < 7 (acidic condition), the preferred orientation is along the (111) direction and for those with pH >7 (alkaline condition), the preferred orientation is along the (200) direction. A lowest resistivity of 9.9 × 10 −4 Ω·cm (with carrier concentration = 5.1 × 10 20 cm −3 , mobility = 12.4 cm 2 /(V·s)) is observed for pH ≈ 12. The resistivity is tuned almost by three orders of magnitude by controlling the bath pH with optical transmittance more than 70%. Thus, the electrical conductivity of CdO films could be easily tuned by simply varying the pH of the spray solution without compromising the optical transparency. (paper)

  14. Effect of Solution pH on the Adsorption of Paracetamol on Chemically Modified Activated Carbons

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    Valentina Bernal

    2017-06-01

    Full Text Available Paracetamol adsorption in acidic, neutral and basic media on three activated carbons with different chemistry surfaces was studied. A granular activated carbon (GAC was prepared from coconut shell; starting from this sample, an oxidized activated carbon (GACo was obtained by treating the GAC with a boiling solution of 6 M nitric acid, so to generate a greater number of oxygenated surface groups. In addition, a reduced activated carbon (GACr was obtained by heating the GAC at 1173 K, to remove the oxygenated surface groups. Paracetamol adsorption was higher for GACr due to the lower presence of oxygenated surface functional groups. Moreover, adsorption was highest at neutral pH. The magnitude of the interactions between paracetamol molecules and activated carbons was studied by measuring the immersion enthalpies of activated carbons in solution of paracetamol at different concentrations and pH values and by calculating the interaction enthalpy. The highest value was obtained for GACr in a paracetamol solution of 1000 mg L−1 at pH 7, confirming that paracetamol adsorption is favoured on basic activated carbons at pH values near to neutrality. Finally, the Gibbs energy changes confirmed the latter result, allowing explaining the different magnitudes of the interactions between paracetamol and activated carbons, as a function of solution pH.

  15. From proton nuclear magnetic resonance spectra to pH. Assessment of {sup 1}H NMR pH indicator compound set for deuterium oxide solutions

    Energy Technology Data Exchange (ETDEWEB)

    Tynkkynen, Tuulia, E-mail: tuulia.tynkkynen@uku.fi [Laboratory of Chemistry, Department of Biosciences, University of Kuopio, PO Box 1627, 70211 Kuopio (Finland); Tiainen, Mika; Soininen, Pasi; Laatikainen, Reino [Laboratory of Chemistry, Department of Biosciences, University of Kuopio, PO Box 1627, 70211 Kuopio (Finland)

    2009-08-19

    In this study, a protocol for pH determination from D{sub 2}O samples using {sup 1}H NMR pH indicator compounds was developed and assessed by exploring the pH-dependency of 13 compounds giving pH-dependent {sup 1}H NMR signals. The indicators cover the pH range from pH* 0 to 7.2. Equations to transform the indicator chemical shifts to pH estimates are given here for acetic acid, formic acid, chloroacetic acid, dichloroacetic acid, creatine, creatinine, glycine, histidine, 1,2,4-triazole, and TSP (2,2,3,3-tetradeutero-3-(trimethylsilyl)-propionic acid). To characterize the method in presence of typical solutes, the effects of common metabolites, albumin and ionic strength were also evaluated. For the ionic strengths, the effects were also modelled. The experiments showed that the use of pH sensitive {sup 1}H NMR chemical shifts allows the pH determination of typical metabolite solutions with accuracy of 0.01-0.05 pH units. Also, when the ionic strength is known with accuracy better than 0.1 mol dm{sup -3} and the solute concentrations are low, pH{sub nmr}{sup *} (the NMR estimate of pH) can be assumed to be within 0.05 pH units from potentiometrically determined pH.

  16. Effect of pH Changes on Antioxidant Capacity and the Content of Betalain Pigments During the Heating of a Solution of Red Beet Betalains

    Directory of Open Access Journals (Sweden)

    Mikołajczyk-Bator Katarzyna

    2017-06-01

    Full Text Available Red beets and their products are mainly consumed after processing. In this study, the effect of pH on changes in antioxidant capacity (AC and the content of betalain pigments were analysed during the heating of a betalain preparation solution. With pH ranging from 4 to 9 during the heat-treatment, the content of red pigments decreased depending on the pH level of the sample. The losses of red pigments in the investigated betalain preparation solution increased along with rising pH levels of the heated solution. The greatest losses were recorded at pH of 9.0. An opposite correlation was observed for yellow pigments. The content of yellow pigments in the heated betalain preparation solution was increasing along with increasing pH. The most pronounced increase in the content of yellow pigments was found at pH of 6.5 and 7.0. At the same time, the heated betalain preparation solution was shown to exhibit a higher antioxidant capacity at pH of 6.0 (14.9 μmol Trolox/mL than at pH of 4.0 (12.6 μmol Trolox/mL. It was observed that the increase in the antioxidant capacity in heated betalain preparation solutions with pH in the 6.0–6.5 range occurred as a result of increased concentrations of neobetanin, assessed by HPLC, within the pH range from 5.0 to 6.5.

  17. Solution and surface chemistry of the Se(IV)-Fe(0) reactions: Effect of initial solution pH.

    Science.gov (United States)

    Xia, Xuefen; Ling, Lan; Zhang, Wei-Xian

    2017-02-01

    Aspects of solution and solid-phase reactions between selenite (Se(IV)) and nanoscale zero-valent iron (nZVI) were investigated. Experimental results on the effects of initial solution pH, formation and evolution of nZVI corrosion products, and speciation of selenium in nZVI were presented. In general, the rate of Se(IV) removal decreases with increasing initial pH. The observed rate constants of Se(IV) removal decreased from 0.3530 to 0.0364 min -1 as pH increased from 4.0 to 10.0. Composition and morphology of nZVI corrosion products and selenium species were characterized using scanning electron microscopy (SEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). Results confirmed that Se(IV) was reduced to Se(0) and Se(-II) by nZVI. Lower solution pH favored further reduction of Se(0) to Se(-II). Amorphous FeOOH, magnetite/maghemite (Fe 3 O 4 /γ-Fe 2 O 3 ) and ferrous hydroxide (Fe(OH) 2 ) were identified as the main corrosion products. Under alkaline conditions, the corrosion products were mainly of Fe(OH) 2 along with small amounts of Fe 3 O 4 , while nZVI in acidic solutions was oxidized to mostly Fe 3 O 4 and amorphous FeOOH. Furthermore, these corrosion products acted as intermediates for electron transfer and reactive/sorptive sites for Se(IV) adsorption and reduction, thus played a crucial role in the removal of aqueous Se(IV). Copyright © 2016. Published by Elsevier Ltd.

  18. Effect of Nitrogen Form and pH of Nutrient Solution on the Shoot Concentration of Phosphorus, Nitrate, and Nitrogen of Spinach in Hydroponic Culture

    OpenAIRE

    N. Najafi; M. Parsazadeh

    2010-01-01

    In order to study the effect of nitrogen form and pH of nutrient solution on the shoot concentration of P, nitrate, organic N + inorganic ammonium, and total N of spinach, a factorial experiment was conducted with two factors including pH of nutrient solution in three levels (4.5, 6.5 and 8.0) and nitrate to ammonium ratio of nutrient solution in five levels (100:0, 75:25, 50:50, 25:75 and 0:100). This factorial experiment was carried out in a completely randomized design with four replicatio...

  19. Determination of free acid in high level liquid wastes by means of fixed pH value

    International Nuclear Information System (INIS)

    Li Jifu; Duan Shirong; Wu Xi; Yu Xueren

    1991-01-01

    For the determination of free acid in high level liquid wastes, 8% potassium oxalate solution with pH 6.50 as a complex agent of hydrolizable ion is added to 1 AW and the solution is titrated with standard sodium hydroxide to reach the original pH value. The quantity of free acid is calculated by standard sodium hydroxide consumed. This method is simple, rapid and accurate. The relative error of analysis is less than ±4%. The average percentage of recovery is 99.6-101.0%

  20. The stability of water- and fat-soluble vitamin in dentifrices according to pH level and storage type.

    Science.gov (United States)

    Park, Jung-Eun; Kim, Ki-Eun; Choi, Yong-Jun; Park, Yong-Duk; Kwon, Ha-Jeong

    2016-02-01

    The purpose of this study is to evaluate the vitamin stabilities in dentifrices by analyzing various vitamins according to the level and storage temperature. The stabilities of water- and fat-soluble vitamins were investigated in buffer solution at different pH values (4, 7, 8, 10 and 11) for 14 days and in dentifrices at different pH (7 and 10) for 5 months at two temperature conditions (room and refrigeration temperature) by analyzing the remaining amounts using HPLC methods. In the buffer solution, the stability of vitamins B1 , B6 and C was increased as the pH values increased. Vitamins E and K showed poor stability at pH 4, and vitamin B3 showed poor stability at pH 11. In dentifrices, the storage temperature highly influenced vitamin stability, especially vitamins C and E, but the stabilities of vitamins B1 and C according to pH values did not correspond to the buffer solution tests. Vitamin B group was relatively stable in dentifrices, but vitamin C completely disappeared after 5 months. Vitamin K showed the least initial preservation rates. Vitamins were not detected in commercial dentifrices for adults and detected amounts were less than the advertised contents in dentifrices for children. Copyright © 2015 John Wiley & Sons, Ltd.

  1. Manganese toxicity in pasture legumes. II. Effects of pH and molybdenum levels in the substrate

    Energy Technology Data Exchange (ETDEWEB)

    Truong, N V; Andrew, C S; Wilson, G L

    1971-06-01

    The effects of pH and Mo levels in the growing media on Mn toxicity were investigated for white clover and five tropical pasture legume species. In solution culture, high Mo supply did not influence Mn toxicity. However, in two species, it caused Mo toxicity. High solution pH intensified Mn toxicity in white clover, probably by way of uptake. The effects of Ca and P on Mn toxicity reported in a previous paper, were not greatly influenced by solution pH. In the soil, Mo application greatly increased dry matter yield of white clover grown on soils high in exchangeable Mn. This effect was more easily attributed to an influence on N metabolism of the legume plant than on Mn toxicity. Measured soil pH was found to have little influence on the level of exchangeable Mn in the soil. However the larger pH changes in small soil pockets, resulting from non-uniform incorporation of chemicals in the soil, might have a more important effect on this fraction of soil Mn. 31 references, 7 tables.

  2. Characterizing the correlation between dephosphorization and solution pH in a calcined water treatment plant sludge.

    Science.gov (United States)

    Zhou, Zhenming; Liu, Qidi; Li, Shuwen; Li, Fei; Zou, Jing; Liao, Xiaobin; Yuan, Baoling; Sun, Wenjie

    2018-04-26

    This study focused on characterizing the correlation between the dephosphorization process of calcined water treatment plant sludge (C-WTPS) and the solution initial pH in batch experiments. The specific aim was to illustrate the effect of different initial pH on the adsorption and desorption of phosphorous in C-WTPS. In addition, the effects of solution initial pH on the release of ammonia nitrogen and total organic carbon (TOC) from C-WTPS and the change of pH after adsorption were also investigated. The results demonstrated that the initial pH significantly influenced the adsorption of phosphorus on C-WTPS. When initial pH was increased from 3 to 10, the phosphorous absorption capacity reduced by 76.5%. Especially, when the initial pH reached to 11, the phosphorus adsorption capacity became a negative value, indicating that C-WTPS released phosphorus into the solution. The addition of C-WTPS to the solution had little impact on the initial pH of the solution. The absorbed phosphorous on C-WTPS was relatively stable in the pH range of 3 to 10. Nevertheless, when the solution pH was higher than 11, it can be easily released into the solution. Furthermore, by comparison with WTPS, C-WTPS released less ammonia nitrogen and TOC into the solution and adsorbed more phosphorus from the solution in the experimental pH range. Therefore, C-WTPS is more suitable to serve as a cost-effective sorbent for phosphorus removal.

  3. Biodesulfurization of vanadium-bearing titanomagnetite concentrates and pH control of bioleaching solution

    Science.gov (United States)

    Liu, Xiao-rong; Jiang, Sheng-cai; Liu, Yan-jun; Li, Hui; Wang, Hua-jun

    2013-10-01

    Vanadium-bearing titanomagnetite concentrates were desulfurized with Acidithiobacillus ferrooxidans ( A. ferrooxidans). The sulfur content of the concentrates was reduced from 0.69wt% to 0.14wt% after bioleaching for 15 d with a 10% pulp density at 30°C. Maintaining a stable pH value during biodesulfurization was critical because of high acid consumption, resulting from a combination of nonoxidative and oxidative dissolution of pyrrhotite in acid solution. It is discovered that the citric acid-disodium hydrogen phosphate buffer of pH 2.0 can control the solution pH value smoothly in the optimal range of 2.0-3.0 for A. ferrooxidans growth. Using the buffer in the volume fraction range of 5.0%-15.0% stimulates A. ferrooxidans growth and improves the biodesulfurization efficiency. Compared with the buffer-free control case, the maximum increase of biodesulfurization rate is 29.7% using a 10.0vol% buffer. Bioleaching provides an alternative process for desulfurization of vanadium-bearing titanomagnetite ores.

  4. Temperature and pH driven association in uranyl aqueous solutions

    Directory of Open Access Journals (Sweden)

    M. Druchok

    2012-12-01

    Full Text Available An association behavior of uranyl ions in aqueous solutions is explored. For this purpose a set of all-atom molecular dynamics simulations is performed. During the simulation, the fractions of uranyl ions involved in dimer and trimer formations were monitored. To accompany the fraction statistics one also collected distributions characterizing average times of the dimer and trimer associates. Two factors effecting the uranyl association were considered: temperature and pH. As one can expect, an increase of the temperature decreases an uranyl capability of forming the associates, thus lowering bound fractions/times and vice versa. The effect of pH was modeled by adding H+ or OH- ions to a "neutral" solution. The addition of hydroxide ions OH- favors the formation of the associates, thus increasing bound times and fractions. The extra H+ ions in a solution produce an opposite effect, thus lowering the uranyl association capability. We also made a structural analysis for all the observed associates to reveal the mutual orientation of the uranyl ions.

  5. Salivary pH levels and caries among siblings and parents within families.

    Science.gov (United States)

    Basch, Yaffa; Peretz, Benjamin

    2013-01-01

    High level of caries activity is related to organisms in the dental plaque with high acidogenesis capacity. To test salivary pH in children of the same family and compare it with their caries status. To compare pH levels between children and their parents. To examine the relationship between pH and caries status among children of the same family and their parents. We examined 123 children and adolescents aged 3-18, (73 boys and 50 girls) and 33 adults, (12 men and 21 women), parents of these children. Caries status was examined clinically, using DMF index. Salivary pH measurements were made by a digital pH meter. Among adults, increase in patient age led to increased DMF (p = 0.005). The higher the pH, the lower the DMF (p = 0.037). Among men, DMF was lower by 3 compared to women (p = 0.049). Children's pH correlated with the parents' (p = 0.004). Children's DMF correlated to their pH (p = 0.001). Children's pH was the best predictor of their DMF (R2 = 0.309, p = 0.001). Among children, the higher the pH, the lower the DMFT. Children's pH was the best predictor of their DMF.

  6. Revealing the Dimeric Crystal and Solution Structure of β-Lactoglobulin at pH 4 and Its pH and Salt Dependent Monomer–Dimer Equilibrium

    DEFF Research Database (Denmark)

    Khan, Sanaullah; Ipsen, Richard; Almdal, Kristoffer

    2018-01-01

    The dimeric structure of bovine β-lactoglobulin A (BLGA) at pH 4.0 was solved to 2.0 Å resolution. Fitting the BLGA pH 4.0 structure to SAXS data at low ionic strength (goodness of fit R-factor = 3.6%) verified the dimeric state in solution. Analysis of the monomer–dimer equilibrium at varying pH...... and ionic strength by SAXS and scattering modeling showed that BLGA is dimeric at pH 3.0 and 4.0, shifting toward a monomer at pH 2.2, 2.6, and 7.0 yielding monomer/dimer ratios of 80/20%, 50/50%, and 25/75%, respectively. BLGA remained a dimer at pH 3.0 and 4.0 in 50–150 mM NaCl, whereas the electrostatic...... shielding raised the dimer content at pH 2.2, 2.6, and 7.0, i.e., below and above the pI. Overall, the findings provide new insights into the molecular characteristics of BLGA relevant for dairy product formulations and for various biotechnological and pharmaceutical applications....

  7. Migration characteristics of cobalt-60 through sandy soil in high pH solution

    International Nuclear Information System (INIS)

    Ohnuki, Toshihiko

    1992-01-01

    Migration characteristics of 60 Co through sandy soil in high pH solution has been investigated by both column and batch techniques. The association of 60 Co with the sandy soil and its components were studied by sequential extraction techniques. The concentration profile of 60 Co in the sandy soil column was composed of two exponential curves showing that 60 Co would consist of immobile and mobile fractions. The immobile 60 Co was retained by the sandy soil and was distributed near the top. Though the mobile 60 Co was little sorbed by soil and migrated through the soil column, maximum concentration of 60 Co in the effluents decreased slightly with increasing path length of the soil column. The sequential extraction of 60 Co from the sandy soil and from its components showed that 60 Co was sorbed by both manganese oxide and clay minerals. And manganese oxide is one of the responsible soil components for the observed decrease in the maximum concentration of 60 Co in the effluents. Although the content of manganese oxide in the sandy soil was 0.13%, manganese oxide is the important component to prevent from the migration of 60 Co in the high pH solution. (author)

  8. Peroxidase-mediated polymerization of 1-naphthol: impact of solution pH and ionic strength.

    Science.gov (United States)

    Bhandari, Alok; Xu, Fangxiang; Koch, David E; Hunter, Robert P

    2009-01-01

    Peroxidase-mediated oxidation has been proposed as a treatment method for naphthol-contaminated water. However, the impact of solution chemistry on naphthol polymerization and removal has not been documented. This research investigated the impact of pH and ionic strength on peroxidase-mediated removal of 1-naphthol in completely mixed batch reactors. The impact of hydrogen peroxide to 1-naphthol ratio and activity of horseradish peroxidase was also studied. Size exclusion chromatography was used to estimate the molecular weight distribution of oligomeric products, and liquid chromatography/mass spectrometry was used to estimate product structure. Naphthol transformation decreased with ionic strength, and substrate removal was lowest at neutral pHs. Solution pH influenced the size and the composition of the oligomeric products. An equimolar ratio of H(2)O(2):naphthol was sufficient for optimal naphthol removal. Polymerization products included naphthoquinones and oligomers derived from two, three, and four naphthol molecules. Our results illustrate the importance of water chemistry when considering a peroxidase-based approach for treatment of naphthol-contaminated waters.

  9. Unusual Salt and pH Induced Changes in Polyethylenimine Solutions.

    Directory of Open Access Journals (Sweden)

    Kimberly A Curtis

    Full Text Available Linear PEI is a cationic polymer commonly used for complexing DNA into nanoparticles for cell-transfection and gene-therapy applications. The polymer has closely-spaced amines with weak-base protonation capacity, and a hydrophobic backbone that is kept unaggregated by intra-chain repulsion. As a result, in solution PEI exhibits multiple buffering mechanisms, and polyelectrolyte states that shift between aggregated and free forms. We studied the interplay between the aggregation and protonation behavior of 2.5 kDa linear PEI by pH probing, vapor pressure osmometry, dynamic light scattering, and ninhydrin assay. Our results indicate that: At neutral pH, the PEI chains are associated and the addition of NaCl initially reduces and then increases the extent of association.The aggregate form is uncollapsed and co-exists with the free chains.PEI buffering occurs due to continuous or discontinuous charging between stalled states.Ninhydrin assay tracks the number of unprotonated amines in PEI.The size of PEI-DNA complexes is not significantly affected by the free vs. aggregated state of the PEI polymer. Despite its simple chemical structure, linear PEI displays intricate solution dynamics, which can be harnessed for environment-sensitive biomaterials and for overcoming current challenges with DNA delivery.

  10. A study of specific sorption of neptunium(V) on smectite in low pH solution

    International Nuclear Information System (INIS)

    Kozai, Naofumi; Ohnuki, Toshihiko; Matsumoto, Junko; Banba, Tsunetaka; Ito, Yoshimoto

    1996-01-01

    The 'specific sorption' of neptunium(V) on smectite, in other words, a strong sorption undesorbable by 1 M KCl, is studied with a combination of batch type sorption and desorption experiments over a pH range of 2 to 5. Six types of homoionic smectite (Li-, Na-, K-, Cs-, Mg-, and Ca-smectite) are used in this study. Distribution coefficients (K d ) of neptunium for smectite vary over a wide pH range; the maximum K d value of ∝300 cm 3 x g -1 at around pH 2 for Li- and Na-smectite and the minimum value of ∝2 cm 3 x g -1 for Cs-smectite. The specific sorption of neptunium depends on pH and on the affinity of the exchangeable cation for smectite; the lower the pH of solution or the affinity, the larger the specific sorption. The neptunium-smectite association varies with the elapse of contact time. Within the first day of the neptunium-smectite contact the neptunium sorbed on na-smectite at low pH is desorbable by 1 M KCl solution, and on the passage of time most of the neuptunium sorbed becomes undesorbable by KCl (the specific sorption). Hydronium ion in solution is sorbed on smectite at low pH and dissociates the exchangeable cation from smectite into solution, and the specific sorption of neuptunium increases with increasing the exchangeable cation that is dissociated from smectite. (orig.)

  11. THE PREDICTION OF pH BY GIBBS FREE ENERGY MINIMIZATION IN THE SUMP SOLUTION UNDER LOCA CONDITION OF PWR

    Directory of Open Access Journals (Sweden)

    HYOUNGJU YOON

    2013-02-01

    Full Text Available It is required that the pH of the sump solution should be above 7.0 to retain iodine in a liquid phase and be within the material compatibility constraints under LOCA condition of PWR. The pH of the sump solution can be determined by conventional chemical equilibrium constants or by the minimization of Gibbs free energy. The latter method developed as a computer code called SOLGASMIX-PV is more convenient than the former since various chemical components can be easily treated under LOCA conditions. In this study, SOLGASMIX-PV code was modified to accommodate the acidic and basic materials produced by radiolysis reactions and to calculate the pH of the sump solution. When the computed pH was compared with measured by the ORNL experiment to verify the reliability of the modified code, the error between two values was within 0.3 pH. Finally, two cases of calculation were performed for the SKN 3&4 and UCN 1&2. As results, pH of the sump solution for the SKN 3&4 was between 7.02 and 7.45, and for the UCN 1&2 plant between 8.07 and 9.41. Furthermore, it was found that the radiolysis reactions have insignificant effects on pH because the relative concentrations of HCl, HNO3, and Cs are very low.

  12. Adsorption of phenol by activated carbon: Influence of activation methods and solution pH

    International Nuclear Information System (INIS)

    Beker, Ulker; Ganbold, Batchimeg; Dertli, Halil; Guelbayir, Dilek Duranoglu

    2010-01-01

    Cherry stone based activated carbon derived from a canning industry was evaluated for its ability to remove phenol from an aqueous solution in a batch process. A comparative adsorption on the uptake of phenol by using commercial activated carbon (Chemviron CPG-LF), and two non-functional commercial polymeric adsorbents (MN-200 and XAD-2) containing a styrene-divinylbenzene macroporous hyperreticulated network have been also examined. Equilibrium studies were conducted in 25 mg L -1 initial phenol concentrations, 6.5-9 solution pH and at temperature of 30 deg. C. The experimental data were analyzed by the Langmuir and Freundlich isotherm models. Besides, the cherry stone based activated carbons were carried out by using zinc chloride and KOH activation agents at different chemical ratios (activating agent/precursor), to develop carbons with well-developed porosity. The cherry stone activated carbon prepared using KOH as a chemical agent showed a high surface area. According to the results, activated carbons had excellent adsorptive characteristics in comparison with polymeric sorbents and commercial activated carbon for the phenol removal from the aqueous solutions.

  13. Seasonal pH and carbondioxide level as indicator of vulnerability of ...

    African Journals Online (AJOL)

    Seasonal pH and carbondioxide level as indicator of vulnerability of fresh and marine ... are already evident but the impact of these changes on marine and coastal living ... and their potential impacts on global climate and aquatic ecosystems.

  14. Gammaradiation effect on spectral properties of oxyhemoglobin solutions of different pH in the presence of serotonin

    International Nuclear Information System (INIS)

    Artyukhov, V.G.

    1979-01-01

    Changes in spectral properties of oxyhemoglobin solutions (pH 3 to 12) of mice exposed to gammaradiation (6000R) in the presence of serotonin have been studied. It was established that serotonin (5x10 -5 M) exerts a radioprotective effect in respect of oxyhemoglobin solutions of pH 5 to 9. Serotonin fails to protect protein in the presence of catalase (1x10 -6 M). It is stated that the process of formation of hydrogen peroxide/serotonin complex appreciably contributes to the protective action of the radioprotective agent in respect of gammairradiated oxyhemoglobin solutions

  15. Relieving Dry Mouth: Varying Levels of pH Found in Bottled Water.

    Science.gov (United States)

    Fisher, Bailey Jean; Spencer, Angela; Haywood, Van; Konchady, Gayathri

    2017-07-01

    It is estimated that 30% of people older than 60 years suffer from hyposalivation or dry mouth. Drinking water frequently has been recommended as a safe, non-pharmacologic way to combat hyposalivation. The saliva in patients with dry mouth is acidic. Beverages consumed daily may have an erosive potential on teeth. The pH and the mineral content of the beverage determine its erosive potential. An acidic beverage, therefore, may have harmful effects on mineralized tooth structures, causing erosion of enamel, dentin, and cementum. Because bottled water is both convenient and easily available, the authors tested the pH of eight common brands of bottled water. (One brand included two different bottle types, for a total of nine bottled waters tested.) To standardize the pH electrode, pH buffers of 4.7 and 10 were used. The pH was measured using the Denver Instruments basic pH meter. Six recordings were used for each brand and then averaged to report the pH. Two of the bottled water samples tested were below the critical level of 5.2 pH to 5.5 pH, the level at which erosion of enamel occurs. Six of the samples tested were below the critical pH of 6.8, at which erosion of root dentin occurs. The authors conclude that both patients and clinicians incorrectly presume bottled water to be innocuous. Clinicians should be cognizant of the erosive potential of different brands of bottled water to both educate patients and to recommend water with neutral or alkaline pH for patients with symptoms of dry mouth to prevent further deterioration and demineralization of tooth structure.

  16. Effect of initial pH and temperature of iron salt solutions on formation of magnetite nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Gnanaprakash, G. [Metallurgy and Materials Group, Indira Gandhi Centre for Atomic Research, Kalpakkam 603 102 (India); Mahadevan, S. [Metallurgy and Materials Group, Indira Gandhi Centre for Atomic Research, Kalpakkam 603 102 (India); Jayakumar, T. [Metallurgy and Materials Group, Indira Gandhi Centre for Atomic Research, Kalpakkam 603 102 (India); Kalyanasundaram, P. [Metallurgy and Materials Group, Indira Gandhi Centre for Atomic Research, Kalpakkam 603 102 (India); Philip, John [Metallurgy and Materials Group, Indira Gandhi Centre for Atomic Research, Kalpakkam 603 102 (India)]. E-mail: philip@igcar.gov.in; Raj, Baldev [Metallurgy and Materials Group, Indira Gandhi Centre for Atomic Research, Kalpakkam 603 102 (India)

    2007-05-15

    We report the effect of initial pH and temperature of iron salt solutions on formation of magnetite (Fe{sub 3}O{sub 4}) nanoparticles during co-precipitation. We synthesized nanoparticles by keeping the initial pH at 0.7, 1.5, 3.0, 4.7, 5.7, 6.7 for two different temperatures of 30 and 60 deg. C. When the initial pH (prior to alkali addition) of the salt solution was below 5, the nanoparticles formed were 100% spinel iron oxide. Average size of the magnetite particles increases with initial pH until ferrihydrite is formed at a pH of 3 and the size remains the same till 4.7 pH. The percentage of goethite formed along with non-stoichiometric magnetite was 35 and 78%, respectively, when the initial pH of the solution was 5.7 and 6.7. As the reaction temperature was increased to 60 deg. C, maintaining a pH of 6.7, the amount of goethite increased from 78 to 100%. These results show that the initial pH and temperature of the ferrous and ferric salt solution before initiation of the precipitation reaction are critical parameters controlling the composition and size of nanoparticles formed. We characterize the samples using X-ray diffraction, transmission electron microscopy and vibrating sample magnetometer. The results of the present work provide the right conditions to synthesis pure magnetite nanoparticles, without goethite impurities, through co-precipitation technique for ferrofluid applications.

  17. Effects of pH on the stability of cyanidin and cyanidin 3-O-β-glucopyranoside in aqueous solution

    Directory of Open Access Journals (Sweden)

    Rakić Violeta P.

    2015-01-01

    Full Text Available The colour variation, colour intensity and stability at various pH values (2.0, 4.0, 7.0 and 9.0 of cyanidin 3-O-β-glucopyranoside (Cy3Glc and its aglycone cyanidin was investigated during a period of 8 hours storage at 25ºC. Our data showed that pH of aqueous solution had impact on spectroscopic profile of cyanidin and Cy3Glc. Beginning with the most acidic solutions, increasing the pH induce bathochromic shifts of absorbance maximum in the visible range for all examined pH values (with the exception pH 4.0 for cyanidin, while the presence of the 3-glucosidic substitution induce hypsochromic shift. Compared to cyanidin, Cy3Glc has higher colour intensity and higher stability in the whole pH range, except at pH 7.0. The 3-glucosidic substitution influences on the colour intensity of Cy3Glc in the alkaline region. After 8-hour incubation of Cy3Glc and cyanidin at pH 2.0 and 25 ºC, 99% of Cy3Glc and only 27% of cyanidin remained unchanged.

  18. Requirements for Ion and Solute Transport, and pH Regulation During Enamel Maturation

    Science.gov (United States)

    LACRUZ, RODRIGO S.; SMITH, CHARLES E.; MOFFATT, PIERRE; CHANG, EUGENE H.; BROMAGE, TIMOTHY G.; BRINGAS, PABLO; NANCI, ANTONIO; BANIWAL, SANJEEV K.; ZABNER, JOSEPH; WELSH, MICHAEL J.; KURTZ, IRA; PAINE, MICHAEL L.

    2012-01-01

    Transcellular bicarbonate transport is suspected to be an important pathway used by ameloblasts to regulate extracellular pH and support crystal growth during enamel maturation. Proteins that play a role in amelogenesis include members of the ABC transporters (SLC gene family and CFTR). A number of carbonic anhydrases (CAs) have also been identified. The defined functions of these genes are likely interlinked during enamel mineralization. The purpose of this study is to quantify relative mRNA levels of individual SLC, Cftr, and CAs in enamel cells obtained from secretory and maturation stages on rat incisors. We also present novel data on the enamel phenotypes for two animal models, amutant porcine(CFTR-ΔF508) and the NBCe1-null mouse.Our data show that two SLCs(AE2 and NBCe1),Cftr,and Car2, Car3,Car6,and Car12 are all significantly up-regulated at the onset of the maturation stage of amelogenesis when compared to the secretory stage. The remaining SLCs and CA gene transcripts showed negligible expression or no significant change in expression from secretory to maturation stages. The enamel of Cftr-ΔF508 adult pigs was hypomineralized and showed abnormal crystal growth. NBCe1-null mice enamel was structurally defective and had a marked decrease in mineral content relative to wild-type. These data demonstrate the importance of many non-matrix proteins to amelogenesis and that the expression levels of multiple genes regulating extracellular pH are modulated during enamel maturation in response to an increased need for pH buffering during hydroxyapatite crystal growth. PMID:21732355

  19. Integrating chemical imaging of cationic trace metal solutes and pH into a single hydrogel layer

    International Nuclear Information System (INIS)

    Hoefer, Christoph; Santner, Jakob; Borisov, Sergey M.; Wenzel, Walter W.; Puschenreiter, Markus

    2017-01-01

    Gel-based, two-dimensional (2D) chemical imaging techniques are versatile methods for investigating biogeochemically active environments at high spatial resolution (sub-mm). State-of-the-art solute imaging techniques, such as diffusive gradients in thin films (DGT) and planar optodes (PO), employ passive solute sampling or sensing. Combining these methods will provide powerful tools for studying the biogeochemistry of biological niches in soils and sediments. In this study we aimed at developing a combined single-layer gel for direct pH imaging using PO and sampling of anionic and cationic solutes by DGT, with subsequent analysis of the bound solutes by laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). We tested three ultra-thin (<100 μm) polyurethane-based gels, incorporating anion and cation binding materials and the fluorescent pH indicator DCIFODA (2′,7′-dichloro-5(6)-N-octadecyl-carboxamidofluorescein). Results showed that PO-based pH sensing using DCIFODA was impossible in the presence of the anion binding materials due to interferences with DCIFODA protonation. One gel, containing only a cation binding material and DCIFODA, was fully characterized and showed similar performance characteristics as comparable DGT-only gels (applicable pH range: pH 5–8, applicable ionic strength range: 1–20 mmol L"-"1, cation binding capacity ∼24 μg cm"−"2). The dynamic range for PO-based pH mapping was between pH 5.5 and 7.5 with t_9_0 response time of ∼60 min. In a case study we demonstrated the gel's suitability for multi-analyte solute imaging and mapped pH gradients and concurrent metal solubility patterns in the rhizosphere of Salix smithiana. pH decreases in the rooted soil were co-localized with elevated solute fluxes of Al"3"+, Co"2"+, Cu"2"+, Fe, Mn"2"+, Ni"2"+ and Pb"2"+, indicating pH-induced metal solubilisation. - Highlights: • Diffusive gradients in thin films (DGT) and planar optode (PO) imaging is combined. • A

  20. Integrating chemical imaging of cationic trace metal solutes and pH into a single hydrogel layer

    Energy Technology Data Exchange (ETDEWEB)

    Hoefer, Christoph [Department of Forest and Soil Sciences, Institute of Soil Research, University of Natural Resources and Life Sciences, Vienna, Konrad-Lorenz-Strasse 24, A-3430 Tulln (Austria); Santner, Jakob, E-mail: jakob.santner@boku.ac.at [Department of Forest and Soil Sciences, Institute of Soil Research, University of Natural Resources and Life Sciences, Vienna, Konrad-Lorenz-Strasse 24, A-3430 Tulln (Austria); Department of Crop Sciences, Division of Agronomy, University of Natural Resources and Life Sciences, Vienna, Konrad-Lorenz-Strasse 24, 3430 Tulln (Austria); Borisov, Sergey M. [Institute of Analytical Chemistry and Food Chemistry, Graz University of Technology, Stremayrgasse 9, A-8010, Graz (Austria); Wenzel, Walter W.; Puschenreiter, Markus [Department of Forest and Soil Sciences, Institute of Soil Research, University of Natural Resources and Life Sciences, Vienna, Konrad-Lorenz-Strasse 24, A-3430 Tulln (Austria)

    2017-01-15

    Gel-based, two-dimensional (2D) chemical imaging techniques are versatile methods for investigating biogeochemically active environments at high spatial resolution (sub-mm). State-of-the-art solute imaging techniques, such as diffusive gradients in thin films (DGT) and planar optodes (PO), employ passive solute sampling or sensing. Combining these methods will provide powerful tools for studying the biogeochemistry of biological niches in soils and sediments. In this study we aimed at developing a combined single-layer gel for direct pH imaging using PO and sampling of anionic and cationic solutes by DGT, with subsequent analysis of the bound solutes by laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). We tested three ultra-thin (<100 μm) polyurethane-based gels, incorporating anion and cation binding materials and the fluorescent pH indicator DCIFODA (2′,7′-dichloro-5(6)-N-octadecyl-carboxamidofluorescein). Results showed that PO-based pH sensing using DCIFODA was impossible in the presence of the anion binding materials due to interferences with DCIFODA protonation. One gel, containing only a cation binding material and DCIFODA, was fully characterized and showed similar performance characteristics as comparable DGT-only gels (applicable pH range: pH 5–8, applicable ionic strength range: 1–20 mmol L{sup -1}, cation binding capacity ∼24 μg cm{sup −2}). The dynamic range for PO-based pH mapping was between pH 5.5 and 7.5 with t{sub 90} response time of ∼60 min. In a case study we demonstrated the gel's suitability for multi-analyte solute imaging and mapped pH gradients and concurrent metal solubility patterns in the rhizosphere of Salix smithiana. pH decreases in the rooted soil were co-localized with elevated solute fluxes of Al{sup 3+}, Co{sup 2+}, Cu{sup 2+}, Fe, Mn{sup 2+}, Ni{sup 2+} and Pb{sup 2+}, indicating pH-induced metal solubilisation. - Highlights: • Diffusive gradients in thin films (DGT) and planar

  1. Influence of pH, temperature and thermal treatment on site corrosion of SAE 304 steel in chlorinated solutions

    International Nuclear Information System (INIS)

    Konrad, I.B.

    1982-01-01

    The electrochemical behaviour and fracture morphology of homogenized and sensitized type SAE 304 stainless steel U bent specimens, in 3% NaCl solution, at pH=2.0 and pH=7.0 both at room temperature and 100 0 C was studied. Polarization curves, galvanostatic and potentiostatic experiments were run. It could be observed that high temperature and low pH favour transgranular cracking and longer sensitization times lower fracture time and tend to give rise to intergranular fracture. Light sensitization can produce transgranular cracking even at room temperature, when the homogenized alloy does not present stress-corrosion cracking for the same condition. (Author) [pt

  2. Sorption behavior of cesium on various soils under different pH levels

    International Nuclear Information System (INIS)

    Giannakopoulou, F.; Haidouti, C.; Chronopoulou, A.; Gasparatos, D.

    2007-01-01

    In the present study we investigated the sorption behavior of Cs in four different soils (sandyloam, loam, clayloam and clay) by using batch experiment. Cs sorption characteristics of the studied soils were examined at 4 mg L -1 Cs concentration, at various pH levels, at room temperature and with 0.01 M CaCl 2 as a background electrolyte. Among different soils the decrease of k d (distribution coefficient) of cesium, at all pH levels, followed the sequence sandyloam > loam > clayloam > clay, indicating that the particle size fractions and especially the clay content plays predominant role on sorption of Cs. The effect of pH on cesium sorption displays a similar pattern for all soils, depending on soil type. At acid pH levels less cesium was sorbed, due to a greater competition with other cations for available sorption sites. The maximum sorption of Cs was observed at pH 8, where the negative charge density on the surface of the absorbents was the highest. For all soils was observed significantly lower Cs sorption at pH 10

  3. Inactivation of Escherichia coli by ozone treatment of apple juice at different pH levels.

    Science.gov (United States)

    Patil, S; Valdramidis, V P; Cullen, P J; Frias, J; Bourke, P

    2010-09-01

    This research investigated the efficacy of gaseous ozone on the inactivation of Escherichia coli ATCC 25922 and NCTC 12900 strains in apple juice of a range of pH levels, using an ozone bubble column. The pH levels investigated were 3.0, 3.5, 4.0, 4.5 and 5.0. Apple juice inoculated with E. coli strains (10(6)CFU/mL) was treated with ozone gas at a flow rate of 0.12L/min and ozone concentration of 0.048 mg/min/mL for up to 18 min. Results show that inactivation kinetics of E. coli by ozone were affected by pH of the juice. The ozone treatment duration required for achieving a 5-log reduction was faster (4 min) at the lowest pH than at the highest pH (18 min) studied. The relationship between time required to achieve 5log reduction (t(5d)) and pH for both strains was described mathematically by two exponential equations. Ozone treatment appears to be an effective process for reducing bacteria in apple juice and the required applied treatment for producing a safe apple juice is dependant on its acidity level. Copyright 2010 Elsevier Ltd. All rights reserved.

  4. Chemical Composition and Evaluation of Nicotine, Tobacco Alkaloids, pH and Selected Flavors in e-Cigarette Cartridges and Refill Solutions

    Science.gov (United States)

    Lisko, Joseph G.; Tran, Hang; Stanfill, Stephen B.; Blount, Benjamin C.; Watson, Clifford H.

    2015-01-01

    Introduction Electronic cigarette (e-cigarette) use is increasing dramatically in developed countries, but little is known about these rapidly evolving products. This study analyzed and evaluated the chemical composition including nicotine, tobacco alkaloids, pH and flavors in 36 e-liquids brands from four manufacturers. Methods We determined the concentrations of nicotine, alkaloids, and select flavors and measured pH in solutions used in e-cigarettes. E-cigarette products were chosen based upon favorable consumer approval ratings from online review websites. Quantitative analyses were performed using strict quality assurance/quality control (QC) validated methods previously established by our lab for the measurement of nicotine, alkaloids, pH and flavors. Results Three-quarters of the products contained lower measured nicotine levels than the stated label values (6% - 42% by concentration). The pH for e-liquids ranged from 5.1 – 9.1. Minor tobacco alkaloids were found in all samples containing nicotine, and their relative concentrations varied widely among manufacturers. A number of common flavor compounds were analyzed in all e-liquids. Conclusions Free nicotine levels calculated from the measurement of pH correlated with total nicotine content. The direct correlation between the total nicotine concentration and pH suggests that the alkalinity of nicotine drives the pH of e-cigarette solutions. A higher percentage of nicotine exists in the more absorbable free form as total nicotine concentration increases. A number of products contained tobacco alkaloids at concentrations that exceed U.S. Pharmacopeia limits for impurities in nicotine used in pharmaceutical and food products. PMID:25636907

  5. Chemical Composition and Evaluation of Nicotine, Tobacco Alkaloids, pH, and Selected Flavors in E-Cigarette Cartridges and Refill Solutions.

    Science.gov (United States)

    Lisko, Joseph G; Tran, Hang; Stanfill, Stephen B; Blount, Benjamin C; Watson, Clifford H

    2015-10-01

    Electronic cigarette (e-cigarette) use is increasing dramatically in developed countries, but little is known about these rapidly evolving products. This study analyzed and evaluated the chemical composition including nicotine, tobacco alkaloids, pH, and flavors in 36 e-liquids brands from 4 manufacturers. We determined the concentrations of nicotine, alkaloids, and select flavors and measured pH in solutions used in e-cigarettes. E-cigarette products were chosen based upon favorable consumer approval ratings from online review websites. Quantitative analyses were performed using strict quality assurance/quality control validated methods previously established by our lab for the measurement of nicotine, alkaloids, pH, and flavors. Three-quarters of the products contained lower measured nicotine levels than the stated label values (6%-42% by concentration). The pH for e-liquids ranged from 5.1-9.1. Minor tobacco alkaloids were found in all samples containing nicotine, and their relative concentrations varied widely among manufacturers. A number of common flavor compounds were analyzed in all e-liquids. Free nicotine levels calculated from the measurement of pH correlated with total nicotine content. The direct correlation between the total nicotine concentration and pH suggests that the alkalinity of nicotine drives the pH of e-cigarette solutions. A higher percentage of nicotine exists in the more absorbable free form as total nicotine concentration increases. A number of products contained tobacco alkaloids at concentrations that exceed U.S. pharmacopeia limits for impurities in nicotine used in pharmaceutical and food products. © Published by Oxford University Press on behalf of the Society for Research on Nicotine and Tobacco 2015. This work is written by (a) US Government employee(s) and is in the public domain in the US.

  6. Effect of pH on the corrosion behaviour of SUS321 in the ammonia aqueous solution

    International Nuclear Information System (INIS)

    Park, Sang Yoon; Jeong, Y. H.; Baek, J. H.; Choi, B. K.; Lee, M. H.; Choi, B. S.; Yoon, J. H.; Lee, D. J.

    2003-02-01

    The corrosion characteristics of SUS321 for pressure vessel of SMART in pure water, ammonia aqueous solutions of pH 8.5 ∼ 11.5 at 300 .deg. C were evaluated by using static autoclaves. SUS321 specimen in the high temperature ammonia aqueous solution has weight gain or loss by the 4 reactions. And it depends on the refreshing period of the aqueous solution. So additional experiments by recirculating loop system were required to evaluate the corrosion behaviour of SUS321 in the ammonia aqueous solution

  7. Enzymatic characterization of peptidic materials isolated from aqueous solutions of ammonium cyanide (pH 9) and hydrocyanic acid (pH 6) exposed to ionizing radiation.

    Science.gov (United States)

    Niketic, V; Draganić, Z; Nesković, S; Draganić, I

    1982-01-01

    The enzymatic digestion of some radiolytically produced peptidic materials was examined. The substrates were compounds isolated from 0.1 molar solutions of NH4CN (pH 9) and HCN (pH 6), after their exposure to gamma rays from a 60Co source (15-20 Mrad doses). Commercial proteolytic enzymes pronase and aminopeptidase M were used. The examined materials were of composite nature and proteolytic action was systematically observed after their subsequent purification. In some fractions the effect was found to be positive with up to 30% of peptide bonds cleaved with respect to the amino acid content. These findings support our previous conclusions on the free radical induced formation of peptidic backbones without the intervention of amino acids. Some side effects were also noted which might be of interest in observations on enzymatic cleavage of other composite peptidic materials of abiotic origin.

  8. Influence of pH and oxygen content of buffer solutions on the corrosion behaviour of metallic materials

    International Nuclear Information System (INIS)

    Wiedemann, K.H.

    1977-05-01

    The application of solutions to the decontamination of materials in nuclear installations is based on the condition that their corrosion behaviour is clearly understood. Since electrochemical corrosion is due to cathodic and anodic partial reactions which are influenced in different ways by the pH of the solution and the oxygen content it is suggested that the results of electrochemical experiments with buffer solutions be used as a model for predicting the corrosion behaviour of materials in other solutions. In the tests described here potentio-kinetic current-potential-curves have been traced and galvanic corrosion tests have been made. The results obtained in ascorbic acid, potassium hydrogen phthalate, ammonium citrate and acetate, sodium and potassium tartrate, ammonium hydrogen phosphate, sodium carbonate, hexamethylene tetramin, ethylene diamine enable - on the basis of summarized current-potential-curves - the metals studied to be classified in four groups characterized by clear differences concerning the influence of pH on the corrosion behaviour. (Auth.)

  9. Comparative study of buffered 50% glycolic acid (pH 3.0) + 0.5% salicylic acid solution vs Jessner's solution in patients with acne vulgaris.

    Science.gov (United States)

    In Jae, Jeong; Dong Ju, Hyun; Dong Hyun, Kim; Yoon, Moon Soo; Lee, Hee Jung

    2017-11-21

    Superficial chemical peels are frequently used in acne vulgaris treatment. Although glycolic acid (GA) has been widely used in clinical practice, its pH ranges from 0.08-2.75 and thus should be neutralized after application to avoid burns. To evaluate treatment efficacy and safety of chemical peeling using buffered 50% GA (pH 3.0) + 0.5% salicylic acid (SA) solution that does not need to be neutralized in the treatment of acne vulgaris compared to the conventional peeling using Jessner's solution. We performed a prospective, randomized, evaluator-blind, split-face clinical trial. Twenty patients were randomized by assigning one side of each patient's face to receive a 50% GA (pH 3.0) + 0.5% SA peel (GA side) and the other side to receive the Jessner's solution (Jessner's solution side). All patients underwent 2 sessions of treatment spaced 2 weeks apart. Lesion count, acne severity, subjective efficacy assessment, and side effects were evaluated. The total lesion count was significantly reduced for the GA and Jessner's solution sides (P  .05). The GA side had fewer side effects than the Jessner's solution side. The results of this study suggest that chemical peeling using the 50% GA (pH 3.0) + 0.5% SA solution can be as effective and convenient as the conventional peeling using Jessner's solution in the treatment of acne vulgaris and may show fewer adverse events than the conventional peeling. © 2017 Wiley Periodicals, Inc.

  10. [Aluminum dissolution and changes of pH in soil solution during sorption of copper by aggregates of paddy soil].

    Science.gov (United States)

    Xu, Hai-Bo; Zhao, Dao-Yuan; Qin, Chao; Li, Yu-Jiao; Dong, Chang-Xun

    2014-01-01

    Size fractions of soil aggregates in Lake Tai region were collected by the low-energy ultrasonic dispersion and the freeze-desiccation methods. The dissolution of aluminum and changes of pH in soil solution during sorption of Cu2+ and changes of the dissolution of aluminum at different pH in the solution of Cu2+ by aggregates were studied by the equilibrium sorption method. The results showed that in the process of Cu2+ sorption by aggregates, the aluminum was dissoluted and the pH decreased. The elution amount of aluminum and the decrease of pH changed with the sorption of Cu2+, both increasing with the increase of Cu2+ sorption. Under the same conditions, the dissolution of aluminum and the decrease of pH were in the order of coarse silt fraction > silt fraction > sand fraction > clay fraction, which was negatively correlated with the amount of iron oxide, aluminum and organic matter. It suggested that iron oxide, aluminum and organic matters had inhibitory and buffering effect on the aluminum dissolution and the decrease of pH during the sorption of Cu2+.

  11. Dansyl-8-aminoquinoline as a sensitive pH fluorescent probe with dual-responsive ranges in aqueous solutions.

    Science.gov (United States)

    Zhang, Min; Zheng, Shuyu; Ma, Liguo; Zhao, Meili; Deng, Lengfang; Yang, Liting; Ma, Li-Jun

    2014-04-24

    A sensitive pH fluorescent probe based on dansyl group, dansyl-8-aminoquinoline (DAQ), has been synthesized. The probe showed dual-responsive ranges to pH changes, one range from 2.00 to 7.95 and another one from 7.95 to 10.87 in aqueous solution, as it showed pKa values of 5.73 and 8.56 under acid and basic conditions, respectively. Furthermore, the pH response mechanism of the probe was explored successfully by using NMR spectra. The results indicated that the responses of DAQ to pH changes should attribute to the protonation of the nitrogen atom in the dimethylamino group and deprotonation of sulfonamide group. Copyright © 2014. Published by Elsevier B.V.

  12. Effect of Aging Temperature on Corrosion Behavior of Sintered 17-4 PH Stainless Steel in Dilute Sulfuric Acid Solution

    Science.gov (United States)

    Szewczyk-Nykiel, Aneta; Kazior, Jan

    2017-07-01

    The general corrosion behavior of sintered 17-4 PH stainless steel processed under different processing conditions in dilute sulfuric acid solution at 25 °C was studied by open-circuit potential measurement and potentiodynamic polarization technique. The corrosion resistance was evaluated based on electrochemical parameters, such as polarization resistance, corrosion potential, corrosion current density as well as corrosion rate. The results showed that the precipitation-hardening treatment could significantly improve the corrosion resistance of the sintered 17-4 PH stainless steel in studied environment. As far as the influence of aging temperature on corrosion behavior of the sintered 17-4 PH stainless steel is concerned, polarization resistance and corrosion rate are reduced with increasing aging temperature from 480 up to 500 °C regardless of the temperature of solution treatment. It can be concluded that the highest corrosion resistance in 0.5 M H2SO4 solution exhibits 17-4 PH after solution treatment at 1040 °C followed by aging at 480 °C.

  13. A new slurry pH model accounting for effects of ammonia and carbon dioxide volatilization on solution speciation

    DEFF Research Database (Denmark)

    Petersen, V.; Markfoged, R.; Hafner, S. D.

    2014-01-01

    a reduced variable that combines time and location and an analytical approach to solving the resulting system of equations using Mathematica. To evaluate the model, we made measurements of pH at a resolution of 0.1 mm in the top 30 mm of an ammonium bicarbonate solution. These measurements show the creation...

  14. Effects of solution pH and complexing reagents on uranium and thorium desorption under saturated equilibrium conditions

    International Nuclear Information System (INIS)

    Wang, Yug-Yea; Yu, C.

    1992-01-01

    Three contaminated bulk surface soils were used for investigating the effect of solution pH and complexing reagents on uranium and thorium desorption. At a low solution pH, the major chemical species of uranium and thorium, uranyl UO 2 +2 , thorium dihydroxide Th(OH) 2 +2 , and thorium hydroxide Th(OH) +3 , tend to form complexes with acetates in the solution phase, which increases the fractions of uranium and thorium desorbed into this phase. At a high solution pH, important uranium and thorium species such as uranyl tricarbonate complex UO 2 (CO) 33 -4 and thorium tetrahydroxide complex Th(OH) 4 tend to resist complexation with acetates. The presence of complexing reagents in solution can release radionuclides such as uranium and/or thorium from the soil to the solution by forming soluble complexes. Sodium bicarbonate (NaHCO 3 ) and diethylenetriaminepentaacetic acid (DTPA) are strong complex formers that released 38% to 62% of total uranium activity and 78% to 86% of total thorium activity, respectively, from the soil samples investigated. Solutions of 0.1 molar sodium nitrate (NaNO 3 ) and 0.1 molar sodium sulfate (Na 2 SO 4 ) were not effective complex formers with uranium and thorium under the experimental conditions. Fractions of uranium and thorium desorbed by 0.15g/200ml humic acid ranged from 4.62% to 6.17% and 1.59% to 7.09%, respectively. This work demonstrates the importance of a knowledge of solution chemistry in investigating the desorption of radionuclides

  15. Low-temperature solution processing of palladium/palladium oxide films and their pH sensing performance.

    Science.gov (United States)

    Qin, Yiheng; Alam, Arif U; Pan, Si; Howlader, Matiar M R; Ghosh, Raja; Selvaganapathy, P Ravi; Wu, Yiliang; Deen, M Jamal

    2016-01-01

    Highly sensitive, easy-to-fabricate, and low-cost pH sensors with small dimensions are required to monitor human bodily fluids, drinking water quality and chemical/biological processes. In this study, a low-temperature, solution-based process is developed to prepare palladium/palladium oxide (Pd/PdO) thin films for pH sensing. A precursor solution for Pd is spin coated onto pre-cleaned glass substrates and annealed at low temperature to generate Pd and PdO. The percentages of PdO at the surface and in the bulk of the electrodes are correlated to their sensing performance, which was studied by using the X-ray photoelectron spectroscope. Large amounts of PdO introduced by prolonged annealing improve the electrode's sensitivity and long-term stability. Atomic force microscopy study showed that the low-temperature annealing results in a smooth electrode surface, which contributes to a fast response. Nano-voids at the electrode surfaces were observed by scanning electron microscope, indicating a reason for the long-term degradation of the pH sensitivity. Using the optimized annealing parameters of 200°C for 48 h, a linear pH response with sensitivity of 64.71±0.56 mV/pH is obtained for pH between 2 and 12. These electrodes show a response time shorter than 18 s, hysteresis less than 8 mV and stability over 60 days. High reproducibility in the sensing performance is achieved. This low-temperature solution-processed sensing electrode shows the potential for the development of pH sensing systems on flexible substrates over a large area at low cost without using vacuum equipment. Copyright © 2015 Elsevier B.V. All rights reserved.

  16. Influence of pH on Cr(VI) ions removal from aqueous solutions using carboxymethyl cellulose-based hydrogel as adsorbent

    Science.gov (United States)

    Anah, L.; Astrini, N.

    2017-03-01

    The major problem in heavy metal pollution is that these metals are not biodegradable and accordingly accumulate in the bodies of living organisms, causing dangerous diseases and serious cell disorder. According to World Health Organization (WHO), the long term exposure of Cr(VI) levels of over 0.1 ppm causes respiratory problems, liver and kidney damage, and carcinogenicity.Due to its easy operation and of various cheap adsorbents development, adsorption has been proved to be efficient and most economically attractive technique and feasible to the removal of toxic heavy metal from wastewater. The study aimed to report the removal of Cr(VI) ions from aqueous solutions through adsorption process using carboxymethyl cellulose-graft-poly(acrylic acid) (CMC-g-PAA) hydrogel as adsorbent.Effect of pH was studied to remove hexavalent chromium.Graft copolymerization of poly(acrylic acid) onto carboxymethyl cellulose was carried out in the presence of benzoyl peroxide redox initiator and methylenbisacrylamide as crosslinker agent. Batch experiments were carried out to investigate the effects ofinitial pH.The adsorption of Cr(VI) ions as a function of pH was conducted in the initial pH range of 1 to 8. The results indicated that acidic pH strongly favored the adsorption. The optimum pH for adsorption of Cr(VI) ranged from 1 to 3, and the maximum uptake of Cr(VI) from the solution was 6.53 mg/g at pH 1 and 30°C. FTIR spectroscopy, SEM analyses were performed on the adsorbent before and after Cr(VI) binding. All analyses confirmed the complexation of Cr(VI) ions on the adsorbent.

  17. Low pH levels wipe out salmon and trout populations in southernmost Norway

    Energy Technology Data Exchange (ETDEWEB)

    Jensen, K W; Snekvik, E

    1972-01-01

    A gradual decrease in pH has been documented for many Scandinavian rivers and lakes and there is little doubt that the main cause is acid precipitation (1-4). Eggs, fry, and alevins of salmon and brown trout are more susceptible to acid water than are the older fish. A gradually increasing acidity of trout biotopes will cause a reduction in the natural reproduction rate of trout, because eggs and fry succumb, while the older individuals in the population survive, at least until the pH level sinks low enough to affect them, as well. A study of the present situation and examination of the available data show that the salmon populations in a number of rivers in southernmost Norway have been nearly wiped out by low pH values. During the last twenty to thirty years, low pH levels have eliminated the brown trout populations in a great number of lakes and rivers in Norway's southernmost districts. This alarming development is continuing.

  18. Changing noise levels in a high CO2/lower pH ocean

    Science.gov (United States)

    Brewer, P. G.; Hester, K. C.; Peltzer, E. T.; Kirkwood, W. J.

    2008-12-01

    We show that ocean acidification from fossil fuel CO2 invasion and from increased respiration/reduced ventilation, has significantly reduced ocean sound absorption and thus increased ocean noise levels in the kHz frequency range. Below 10 kHz, sound absorption occurs due to well known chemical relaxations in the B(OH)3/B(OH)4- and HCO3-/CO32- systems. The pH dependence of these chemical relaxations results in decreased sound absorption (α = dB/km) as the ocean becomes more acidic from increased CO2 levels. The scale of surface ocean pH change today from the +105 ppmv change in atmospheric CO2 is about - 0.12 pH, resulting in frequency dependent decreases in sound absorption that now exceed 12% over pre- industrial. Under reasonable projections of future fossil fuel CO2 emissions and other sources a pH change of 0.3 units or more can be anticipated by mid-century, resulting in a decrease in α by almost 40%. Increases in water temperature have a smaller effect but also contribute to decreased sound absorption. Combining a lowering of 0.3 pH units with an increase of 3°C, α will decrease further to almost 45%. Ambient noise levels in the ocean within the auditory range critical for environmental, military, and economic interests are set to increase significantly due to the combined effects of decreased absorption and increasing sources from mankind's activities. Incorporation of sound absorption in modeling future ocean scenarios (R. Zeebe, personal communication) and long-term monitoring possibly with the aid of modern cabled observatories can give insights in how ocean noise will continue to change and its effect on groups such as marine mammals which communicate in the affected frequency range.

  19. X-ray absorption spectroscopic study of trivalent and tetravalent actinides in solution at varying pH values

    Energy Technology Data Exchange (ETDEWEB)

    Brendebach, B.; Banik, N.L.; Marquardt, C.M.; Rothe, J.; Denecke, M.A.; Geckeis, H. [Forschungszentrum Karlsruhe (Germany). Inst. fuer Nukleare Entsorgung

    2009-07-01

    We perform X-ray absorption spectroscopy (XAS) investigations to monitor the stabilization of redox sensitive trivalent and tetravalent actinide ions in solution at acidic conditions in a pH range from 0 to 3 after treatment with holding reductants, hydroxylamine hydrochloride (NH{sub 2}OHHCl) and Rongalite (sodium hydroxymethanesulfinate, CH{sub 3}NaO{sub 3}S). X-ray absorption near edge structure (XANES) measurements clearly demonstrate the stability of the actinide species for several hours under the given experimental conditions. Hence, structural parameters can be accurately derived by extended X-ray absorption fine structure (EXAFS) investigations. The coordination structure of oxygen atoms belonging to water ligands surrounding the actinide ions does not change with increasing pH value (approximately 11 O atoms at 2.42 A in the case of U(IV) at pH 1, 9 0 atoms at 2.52 A for Np(III) at pH 1.5, and 10 O atoms at 2.49 A for Pu(III) up to pH 3), indicating that hydrolysis reactions are suppressed under the given chemical conditions. (orig.)

  20. Adsorption of cadmium by activated carbon cloth: influence of surface oxidation and solution pH.

    Science.gov (United States)

    Rangel-Mendez, J R; Streat, M

    2002-03-01

    The surface of activated carbon cloth (ACC), based on polyacrylonitrile fibre as a precursor, was oxidised using nitric acid, ozone and electrochemical oxidation to enhance cadmium ion exchange capacity. Modified adsorbents were physically and chemically characterised by pH titration, direct titration, X-ray photoelectron spectroscopy, elemental analysis, surface area and porosimetry, and scanning electron microscopy. BET surface area decreased after oxidation, however, the total ion exchange capacity increased by a factor of approximately 3.5 compared to the commercial as-received ACC. A very significant increase in cadmium uptake, by a factor of 13, was observed for the electrochemically oxidised ACC. Equilibrium sorption isotherms were determined at pH 4, 5 and 6 and these showed that cadmium uptake increased with increasing pH. There was clear evidence of physical damage to ozone-oxidised fibre, however, acid and electrochemically oxidised samples were completely stable.

  1. Effect of chitosan on the heat stability of whey protein solution as a function of pH.

    Science.gov (United States)

    Zhao, Zhengtao; Xiao, Qian

    2017-03-01

    Chitosan was reported to interact with proteins through electrostatic interactions. Their interaction was influenced by pH, which was not fully characterized. Further research on the interactions between protein and chitosan at different pH and their influence on the thermal denaturation of proteins is necessary. In this research, the effect of chitosan on the heat stability of whey protein solution at pH 4.0-6.0 was studied. At pH 4.0, a small amount chitosan was able to prevent the heat-induced denaturation and aggregation of whey protein molecules. At higher pH values (5.5 and 6.0), whey proteins complexed with chitosan through electrostatic attraction. The formation of chitosan-whey protein complexes at pH 5.5 improved the heat stability of dispersions and no precipitation could be detected up to 20 days. The dispersion with a medium amount of chitosan (chitosan:whey protein 1:5) produced the most stable particles, which had an average radius of 135 ± 14 nm and a zeta potential value of 36 ± 1 mV. In contrast, at pH 6.0 only the dispersion with a high amount of chitosan (chitosan:whey protein 1:2) showed good shelf stability up to 20 days. It was possible to produce heat-stable whey protein beverages by regulating the interaction between chitosan and whey protein molecules. © 2016 Society of Chemical Industry. © 2016 Society of Chemical Industry.

  2. Effect of pH and chloride on the micro-mechanism of pitting corrosion for high strength pipeline steel in aerated NaCl solutions

    International Nuclear Information System (INIS)

    Wang, Yafei; Cheng, Guangxu; Wu, Wei; Qiao, Qiao; Li, Yun; Li, Xiufeng

    2015-01-01

    Highlights: • Pitting behavior of X80 steel in aerated NaCl solutions is studied systematically. • Unique large pit morphology is observed in neutral/acidic NaCl solutions. • In low pH solutions, pit will propagate in the horizontal direction, leading to the shallow shape of pitting morphology; in high pH solutions, the pit sizes are much smaller. • Film growth, which is dependent on the pH and chloride concentration, has great influence on the cathodic reaction by affecting oxygen diffusion process. - Abstract: The pitting corrosion mechanism of high strength pipeline steel in aerated NaCl solutions with different pH and chloride content was investigated, using potentiodynamic polarization, electrochemical impedance spectroscopy (EIS) and scanning electron microscope (SEM). The pitting behavior in alkaline solutions was found to be significantly different from that in neutral and acidic solutions. Electrochemical results and SEM images indicate that the product film formed on the steel surface results in different corrosion behavior in an alkaline solution. SEM images show that pH and chloride concentration in the bulk solution have a great influence on the pitting morphology. Unique large pit morphology due to corrosion in neutral/acidic solutions with 0.05 mol/L NaCl was observed. The relationship between solution pH and the effect of chloride concentration is also discussed

  3. Modified Organosilica Core-Shell Nanoparticles for Stable pH Sensing in Biological Solutions.

    Science.gov (United States)

    Robinson, Kye J; Huynh, Gabriel T; Kouskousis, Betty P; Fletcher, Nicholas L; Houston, Zachary H; Thurecht, Kristofer J; Corrie, Simon R

    2018-04-19

    Continuous monitoring using nanoparticle-based sensors has been successfully employed in complex biological systems, yet the sensors still suffer from poor long-term stability partially because of the scaffold materials chosen to date. Organosilica core-shell nanoparticles containing a mixture of covalently incorporated pH-sensitive (shell) and pH-insensitive (core) fluorophores is presented as a continuous pH sensor for application in biological media. In contrast to previous studies focusing on similar materials, we sought to investigate the sensor characteristics (dynamic range, sensitivity, response time, stability) as a function of material properties. The ratio of the fluorescence intensities at specific wavelengths was found to be highly sensitive to pH over a physiologically relevant range (4.5-8) with a response time of pH-specific signals when stored at room temperature for more than 80 days. Finally, we demonstrated that the nanosensors successfully monitored the pH of a bacterial culture over 15 h and that pH changes in the skin of mouse cadavers could also be observed via in vivo fluorescence imaging following subcutaneous injection. The understanding gained from linking sensor characteristics and material properties will inform the next generation of optical nanosensors for continuous-monitoring applications.

  4. [Relationship between blood glucose levels and salivary pH and buffering capacity in type II diabetes patients].

    Science.gov (United States)

    Elkafri, I H; Mashlah, A; Shaqifa, A

    2014-03-13

    This study was evaluated the relationship between blood glucose levels and salivary pH and buffering capacity in type II diabetic patients. The sample comprised 210 participants (age ranged 40-60 years). Based on fasting blood glucose levels the participants were divided into 3 groups: controls with normal blood glucose levels; diabetic patients with levels ≤ 200 mg/dL; and diabetic patients with levels > 200 mg/dL. Salivary pH and buffering capacity were determined in a sample of resting (non-stimulated) saliva taken from each participant. Salivary pH levels in diabetic patients with blood glucose levels > 200 mg/dL were lower than in the controls and diabetic patients with levels ≤ 200 mg/dL. Salivary pH levels were comparable in controls and diabetic patients with blood glucose levels ≤ 200 mg/dL. Salivary buffering capacity in the 3 groups was comparable.

  5. Analysis of the electric conductivity and pH behaviors in recycled drainage solution of rose cv. Charlotte plants grown in substrate

    Directory of Open Access Journals (Sweden)

    Luis Fernando Yepes V

    2013-12-01

    Full Text Available In open soilless cropping systems contamination from nutrient lixiviation is generated making it necessary to design closed or semi-closed systems, which require the determination of the maximum saline levels in recycling solutions. In this study, the electric conductivity (EC and pH behaviors were analyzed in drainage solution intended for recycling in the crop; in addition, parameters were used to estimate nutrient availability for the plants in a substrate based cropping system. This research project was carried out under greenhouse conditions in the municipality of Mosquera (Colombia. Rose cv. Charlotte grafted on "Natal briar" stocks were used, sown in pots arranged on elevated beds, 15 m in length. This project was carried out using a split-plot design with sub-plots (with the substrate as the main plot and the recycling as the sub-plot, three kinds of substrate and three recycling percentages (0, 50, and 100%, for a total of 27 experimental units. Substrate mixtures based on burned rice husk and coconut fiber were used. Recycling during one harvest cycle of the roses did not show EC and pH values above those that are considered to have a negative impact on production; however, an increasing behavior in the EC and pH values was observed. Likewise, no significant differences between the 50 and 100% recycling were observed, which means 100% recycling can be used, optimizing nutrient use and water conservation

  6. pH sensing characteristics and biosensing application of solution-gated reduced graphene oxide field-effect transistors.

    Science.gov (United States)

    Sohn, Il-Yung; Kim, Duck-Jin; Jung, Jin-Heak; Yoon, Ok Ja; Thanh, Tien Nguyen; Quang, Trung Tran; Lee, Nae-Eung

    2013-07-15

    Solution-gated reduced graphene oxide field-effect transistors (R-GO FETs) were investigated for pH sensing and biochemical sensing applications. A channel of a networked R-GO film formed by self-assembly was incorporated as a sensing layer into a solution-gated FET structure for pH sensing and the detection of acetylcholine (Ach), which is a neurotransmitter in the nerve system, through enzymatic reactions. The fabricated R-GO FET was sensitive to protons (H(+)) with a pH sensitivity of 29 mV/pH in terms of the shift of the charge neutrality point (CNP), which is attributed to changes in the surface potential caused by the interaction of protons with OH surface functional groups present on the R-GO surface. The R-GO FET immobilized with acetylcholinesterase (AchE) was used to detect Ach in the concentration range of 0.1-10mM by sensing protons generated during the enzymatic reactions. The results indicate that R-GO FETs provide the capability to detect protons, demonstrating their applicability as a biosensing device for enzymatic reactions. Copyright © 2013 Elsevier B.V. All rights reserved.

  7. Effects of Iodide and Hydrogen Peroxide on Measuring High Temperature pH in Various Lithium Borate Buffer Solutions

    Energy Technology Data Exchange (ETDEWEB)

    Hwang, Jae Sik; Yun, Myung Hee; Yeon, Jei Won; Song, Kyu Seok [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2008-10-15

    In a reactor coolant system of nuclear power plants, the need for reliable high temperature pH electrodes has resulted from interests in the corrosion and corrosion product behaviors of the structural materials in a high temperature coolant system. In developing the electrodes for measuring the high temperature pH of aqueous solutions, it is necessary to note two major problems: the chemical stability of an electrode against other chemical impurities, and an electrode's integrity as the temperature and pressure are varied between operational extremes. Over the past decade Macdonald et al. and Danielson et al. have developed many ceramic membrane pH electrodes based on a yttrium stabilized zirconium oxide. However, there are still many experimental difficulties associated with the problems in obtaining electrochemical information across different pressure boundaries and against many kinds of chemical impurities caused by the radiolysis of water and the leakage of a fuel clad. In the present work, we investigated the effects of the environmental factors on a high temperature pH. The selected environmental factors are as follows: system pressure, and chemical species such as iodide and hydrogen peroxide ions.

  8. Effect of pH Value on the Electrochemical and Stress Corrosion Cracking Behavior of X70 Pipeline Steel in the Dilute Bicarbonate Solutions

    Science.gov (United States)

    Cui, Z. Y.; Liu, Z. Y.; Wang, L. W.; Ma, H. C.; Du, C. W.; Li, X. G.; Wang, X.

    2015-11-01

    In this work, effects of pH value on the electrochemical and stress corrosion cracking (SCC) behavior of X70 pipeline steel in the dilute bicarbonate solutions were investigated using electrochemical measurements, slow strain rate tensile tests and surface analysis techniques. Decrease of the solution pH from 6.8 to 6.0 promotes the anodic dissolution and cathodic reduction simultaneously. Further decrease of the pH value mainly accelerates the cathodic reduction of X70 pipeline steel. As a result, when the solution pH decreases form 6.8 to 5.5, SCC susceptibility decreases because of the enhancement of the anodic dissolution. When the solution pH decreases from 5.5 to 4.0, SCC susceptibility increases gradually because of the acceleration of cathodic reactions.

  9. Magnetite synthesis from ferrous iron solution at pH 6.8 in a continuous stirred tank reactor.

    Science.gov (United States)

    Mos, Yvonne M; Zorzano, Karin Bertens; Buisman, Cees J N; Weijma, Jan

    2018-04-01

    Partial oxidation of defined Fe 2+ solutions is a well-known method for magnetite synthesis in batch systems. The partial oxidation method could serve as basis for an iron removal process in drinking water production, yielding magnetite (Fe 3 O 4 ) as a compact and valuable product. As a first step toward such a process, a series of experiments was carried out, in which magnetite was synthesized from an Fe 2+ solution in a 2 L continuous stirred tank reactor (CSTR) at atmospheric pressure and 32 °C. In four experiments, elevating the pH from an initial value of 5.5 or 6.0 to a final value of 6.8, 7.0 or 7.5 caused green rust to form, eventually leading to magnetite. Formation of NH 4 + in the reactor indicated that NO 3 - and subsequently NO 2 - served as the oxidant. However, mass flow analysis revealed an influx of O 2 to the reactor. In a subsequent experiment, magnetite formation was achieved in the absence of added nitrate. In another experiment, seeding with magnetite particles led to additional magnetite precipitation without the need for a pH elevation step. Our results show, for the first time, that continuous magnetite formation from an Fe 2+ solution is possible under mild conditions, without the need for extensive addition of chemicals.

  10. The influence of low dose irradiation on intracellular pH level, synthesizing activity and ATP level in cultured chinese fibroblasts

    International Nuclear Information System (INIS)

    Parkhomenko, I.M.; Perishvili, G.V.; Turovetskij, V.B.; Kudryashov, Yu.B.; Rubin, A.B.; Brovko, L.Yu.

    1993-01-01

    X-irradiation of Chinese fibroblasts with doses of 0.05-0.15 Gy was shown to cause intracellular pH (pH i ) changes: its diminishing during the first 40-60 min by 0.16-0.18 pH units, then the return to the control level 120 min after irradiation and, finally, the increase by 0.18-0.20 pH units. Simultaneously, the synthesizing activity of the cells changed in the same way. The ATP level changed in the opposite way: increased when pH fell and decreased when pH grew. It was shown that pH i changes were connected with the changes in Na + /H + -exchange system, and they seemed to be primary in the chain of the alterations observed

  11. Experiments on the effect of sphagnum on the pH of salt solutions

    Energy Technology Data Exchange (ETDEWEB)

    Williams, K T; Thompson, T G

    1936-01-01

    Addition of sphagnum to salt solutions produced marked increases in the concentrations of the hydrogen ions, as measured both electrometrically and colorimetrically. The greater the concentration of the salt solution, the greater the increase in hydrogen ion concentration upon the addition of sphagnum. With a given salt concentration, the hydrogen ion concentration increased with increase in quantity of sphagnum added. The divalent cations produced greater increases in the hydrogen concentration than the monovalent cations for equal weights of sphagnum. Divalent anions, while showing an increase in hydrogen ions, upon the addition of sphagnum were far less effective in increasing the hydrogen ion concentrations. Sphagnum may be a useful reagent for regulating the acidity of salt solutions for many types of scientific work. It seems probable that the adsorption of metallic and hydroxyl ions explains, at least in part, the acidity of the water of sphagnum bogs.

  12. Fabric tensile strength as affected by different anti pilling agents at various concentration and ph levels

    International Nuclear Information System (INIS)

    Tusief, M.Q.; Mahmood, N.; Saleem, M.

    2013-01-01

    Pilling is a phenomenon that has a long cause trouble in textile industry. It is the formation of pills or knops on the surface of woven or knitted fabrics caused by friction and abrasion. If fabric has a pronounced tendency to pilling, their appearances suffer severely after a short period of use. The pilling of fabrics is a serious problem for the apparel industry. The use of anti pilling finishes is one of the best techniques to control the pilling of the fabric. In this method fabric is treated with special anti pilling agents to prevent pilling that promote adhesion of the fibres in the yarn or the fabric. This paper endeavors to optimize the application of different anti pilling agents at different concentration and pH levels on the Tensile Strength of P/C fabric for best results. The results exposed that different anti pilling finishes have significant effects on the Tensile Strength of fabric at different concentration level however different pH levels have no considerable effects. (author)

  13. Parametric Level Statistics in Random Matrix Theory: Exact Solution

    International Nuclear Information System (INIS)

    Kanzieper, E.

    1999-01-01

    During recent several years, the theory of non-Gaussian random matrix ensembles has experienced a sound progress motivated by new ideas in quantum chromodynamics (QCD) and mesoscopic physics. Invariant non-Gaussian random matrix models appear to describe universal features of low-energy part of the spectrum of Dirac operator in QCD, and electron level statistics in normal conducting-superconducting hybrid structures. They also serve as a basis for constructing the toy models of universal spectral statistics expected at the edge of the metal-insulator transition. While conventional spectral statistics has received a detailed study in the context of RMT, quite a bit is known about parametric level statistics in non-Gaussian random matrix models. In this communication we report about exact solution to the problem of parametric level statistics in unitary invariant, U(N), non-Gaussian ensembles of N x N Hermitian random matrices with either soft or strong level confinement. The solution is formulated within the framework of the orthogonal polynomial technique and is shown to depend on both the unfolded two-point scalar kernel and the level confinement through a double integral transformation which, in turn, provides a constructive tool for description of parametric level correlations in non-Gaussian RMT. In the case of soft level confinement, the formalism developed is potentially applicable to a study of parametric level statistics in an important class of random matrix models with finite level compressibility expected to describe a disorder-induced metal-insulator transition. In random matrix ensembles with strong level confinement, the solution presented takes a particular simple form in the thermodynamic limit: In this case, a new intriguing connection relation between the parametric level statistics and the scalar two-point kernel of an unperturbed ensemble is demonstrated to emerge. Extension of the results obtained to higher-order parametric level statistics is

  14. Radiolysis of permanganate and its mixtures with bromate and nitrate ions in solution at pH 10

    International Nuclear Information System (INIS)

    Dedgaonkar, V.G.; Kulkarni, S.A.; Mahajan, C.T.

    1981-01-01

    γ-radiolysis of aqueous solutions of pure permanganate and its binary mixture with nitrite and bromate ions at pH 10 is studied as a function of concentration and dose. In pure system G(-MnO 4 - ) increases with the increase in initial concentration from 0.68 to a maximum of 25. The rise is sharp above 10 -2 M concentration which indicates the occurrence of a chain mechanism. In the presence of bromate or nitrite the G value decreases: the G(-MnO 4 - ) in 10 -3 M permanganate solution is 1.07, with 10 -1 M bromate it is 0.2 and with 10 -2 M nitrite it is 0.7. A mechanism based on the cometitive kinetics is envisaged to explain the observed results. (author)

  15. Radiolysis of nitrite, bromate and permanganate ions and their binary mixtures in aqueous solutions at pH 10

    International Nuclear Information System (INIS)

    Dedgaonkar, V.G.; Kulkarni, S.A.; Mahajan, C.T.

    1981-01-01

    #betta#-radiolysis of pure systems viz. nitrite, bromate and permanganate and their binary mixtures (MNO 4- /NO 2- , MnO 4- /BrO 3- ) in aqueous solution at pH 10 is studied as a function of dose and concentration. In pure systems the G(NO 3- ), G(Br - ) and G(-MnO 4- ) increase with increasing concentration. The first two show an identical limiting value of approximately 0.5 while the last increases from 0.68 below 10 4 M and reaches 2.5 at 10 - 2 M concentration. Presence of 10 - 1 M BrO 3- or 10 - 2 M NO 2- reduces the G(-MnO 4- ) from 1.07 for the pure 10 - 3 M permanganate solution to 0.2 and 0.7 respectively. A mechanism based on the competitive kinetics is envisaged to explain the observed results. (author)

  16. Electrochemical processing of low-level waste solutions

    International Nuclear Information System (INIS)

    Hobbs, D.T.; Ebra, M.A.

    1987-01-01

    The feasibility of treating low-level Savannah River Plant (SRP) waste solutions by an electrolytic process has been demonstrated. Although the economics of the process are marginal at the current densities investigated at the laboratory scale, there are a number of positive environmental benefits. These benefits include: (1) reduction in the levels of nitrate and nitrite in the waste, (2) further decontamination of 99 Tc and 106 Ru, and (3) reduction in the volume of waste

  17. Calorimetric and diffractometric evidence for the sequential crystallization of buffer components and the consequential pH swing in frozen solutions.

    Science.gov (United States)

    Sundaramurthi, Prakash; Shalaev, Evgenyi; Suryanarayanan, Raj

    2010-04-15

    Sequential crystallization of succinate buffer components in the frozen solution has been studied by differential scanning calorimetry and X-ray diffractometry (both laboratory and synchrotron sources). The consequential pH shifts were monitored using a low-temperature electrode. When a solution buffered to pH pK(a)(2), the freeze-concentrate pH first decreased and then increased due to the sequential crystallization of the basic (disodium succinate) followed by the acidic (monosodium succinate and succinic acid) buffer components. XRD provided direct evidence of the crystallization events in the frozen buffer solutions, including the formation of disodium succinate hexahydrate [Na(2)(CH(2)COO)(2).6H(2)O]. When the frozen solution was warmed in a differential scanning calorimeter, multiple endotherms attributable to the melting of buffer components and ice were observed. When the frozen solutions were dried under reduced pressure, ice sublimation was followed by dehydration of the crystalline hexahydrate to a poorly crystalline anhydrate. However, crystalline succinic acid and monosodium succinate were retained in the final lyophiles. The pH and the buffer salt concentration of the prelyo solution influenced the crystalline salt content in the final lyophile. The direction and magnitude of the pH shift in the frozen solution depended on both the initial pH and the buffer concentration. In light of the pH-sensitive nature of a significant fraction of pharmaceuticals (especially proteins), extreme care is needed in both the buffer selection and its concentration.

  18. Relationship between salivary glucosa levels and salivary pH with candidiasis oral in diabetes mellitus patients

    OpenAIRE

    Sumintarti Sumintarti

    2016-01-01

    Diabetes Mellitus (DM) is a metabolic disease which is characterized by increased blood glucose level and also increased salivary glucose level. The disease is characterized by decreasing pH of the saliva. The decrease pH of saliva can the high risk of oral infection. Candidiasis is the most common infection of patients with diabetes mellitus. The purpose of this study was to determine the relationship between salivary glucose level and salivary pH to the occurrence of oral candidiasis in pat...

  19. The effect of solution pH and peroxide in the TiO2-induced photocatalysis of chlorinated aniline

    International Nuclear Information System (INIS)

    Chu, W.; Choy, W.K.; So, T.Y.

    2007-01-01

    Chlorinated anilines are frequently used in the industry as starting materials for chemical synthesis. This type of compounds can end up as pollutants in wastewater. 2-Chloroaniline (2-ClA) was selected irradiating under monochromatic UV light at 300 nm. The reaction rate could be enhanced by introducing low level of H 2 O 2 into the UV/TiO 2 system. Excess H 2 O 2 could not increase the HO· generation but retarded the reaction rate. The pH effect was also investigated in UV/TiO 2 and UV/TiO 2 /H 2 O 2 systems. All the experimental results show that pH is a sensitive parameter to the rate of degradation. Low reaction rate at acidic pH could be accounted by the dark adsorption test which has also proven the photocatalysis of TiO 2 may contribute to a two-step process: (1) 2-ClA pre-adsorbed onto TiO 2 and (2) photoexcitation of TiO 2 . At high pH, rate enhancement could be observed at UV/TiO 2 system because of the increase generation of HO·. However, the introduction of H 2 O 2 slowdown the decay rate at such alkaline medium

  20. Redox properties of phenosafranine at zeolite-modified electrodes-Effect of surface modification and solution pH

    International Nuclear Information System (INIS)

    Easwaramoorthi, S.; Natarajan, P.

    2008-01-01

    Redox properties of cationic dye phenosafranine (3,7-diamino-5-phenylphenazenium chloride) (PS + ) were studied at zeolite-modified electrodes using Zeolite-Y and NaZSM-5. The peak current and peak potential of phenosafranine-adsorbed zeolite were found to be influenced by the pH of the electrolyte solution. Observation of a second redox couple is suggested to be due to formation of new species at low concentration from the reduced phenosafranine at the zeolite-modified electrodes. Titanium dioxide nanoparticles encapsulated in the cavities of the zeolite or anchored on the external surface of the zeolite do not seem to affect the redox properties of adsorbed PS + . When the cyclic voltammograms are recorded immediately after the electrode is immersed into the solution, the redox potential of PS + is found to be sensitive to the nature of the zeolite surface. The peak potential shifts towards positive region under continuous cycles as the surface hydroxyl groups get protonated in acidic electrolyte solution thereby forcing the movement of dye molecules from the zeolite surface to the zeolite electrode solution interface. The electron transfer rate constants for the adsorbed dye at the electrode are calculated to be 2.5 ± 0.2 s -1 and 3.5 ± 0.2 s -1 for the zeolite-Y electrode and the ZSM-5 electrode, respectively by the Laviron equation

  1. Osmotic potential calculations of inorganic and organic aqueous solutions over wide solute concentration levels and temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Cochrane, T. T., E-mail: agteca@hotmail.com [AGTECA S.A., 230 Oceanbeach Road, Mount Maunganui, Tauranga 3116 (New Zealand); Cochrane, T. A., E-mail: tom.cochrane@canterbury.ac.nz [Department of Civil and Natural Resources Engineering, University of Canterbury, Private Bag 4800, Christchurch 8140 (New Zealand)

    2016-01-15

    Purpose: To demonstrate that the authors’ new “aqueous solution vs pure water” equation to calculate osmotic potential may be used to calculate the osmotic potentials of inorganic and organic aqueous solutions over wide ranges of solute concentrations and temperatures. Currently, the osmotic potentials of solutions used for medical purposes are calculated from equations based on the thermodynamics of the gas laws which are only accurate at low temperature and solute concentration levels. Some solutions used in medicine may need their osmotic potentials calculated more accurately to take into account solute concentrations and temperatures. Methods: The authors experimented with their new equation for calculating the osmotic potentials of inorganic and organic aqueous solutions up to and beyond body temperatures by adjusting three of its factors; (a) the volume property of pure water, (b) the number of “free” water molecules per unit volume of solution, “N{sub f},” and (c) the “t” factor expressing the cooperative structural relaxation time of pure water at given temperatures. Adequate information on the volume property of pure water at different temperatures is available in the literature. However, as little information on the relative densities of inorganic and organic solutions, respectively, at varying temperatures needed to calculate N{sub f} was available, provisional equations were formulated to approximate values. Those values together with tentative t values for different temperatures chosen from values calculated by different workers were substituted into the authors’ equation to demonstrate how osmotic potentials could be estimated over temperatures up to and beyond bodily temperatures. Results: The provisional equations formulated to calculate N{sub f}, the number of free water molecules per unit volume of inorganic and organic solute solutions, respectively, over wide concentration ranges compared well with the calculations of N{sub f

  2. Osmotic potential calculations of inorganic and organic aqueous solutions over wide solute concentration levels and temperatures

    International Nuclear Information System (INIS)

    Cochrane, T. T.; Cochrane, T. A.

    2016-01-01

    Purpose: To demonstrate that the authors’ new “aqueous solution vs pure water” equation to calculate osmotic potential may be used to calculate the osmotic potentials of inorganic and organic aqueous solutions over wide ranges of solute concentrations and temperatures. Currently, the osmotic potentials of solutions used for medical purposes are calculated from equations based on the thermodynamics of the gas laws which are only accurate at low temperature and solute concentration levels. Some solutions used in medicine may need their osmotic potentials calculated more accurately to take into account solute concentrations and temperatures. Methods: The authors experimented with their new equation for calculating the osmotic potentials of inorganic and organic aqueous solutions up to and beyond body temperatures by adjusting three of its factors; (a) the volume property of pure water, (b) the number of “free” water molecules per unit volume of solution, “N f ,” and (c) the “t” factor expressing the cooperative structural relaxation time of pure water at given temperatures. Adequate information on the volume property of pure water at different temperatures is available in the literature. However, as little information on the relative densities of inorganic and organic solutions, respectively, at varying temperatures needed to calculate N f was available, provisional equations were formulated to approximate values. Those values together with tentative t values for different temperatures chosen from values calculated by different workers were substituted into the authors’ equation to demonstrate how osmotic potentials could be estimated over temperatures up to and beyond bodily temperatures. Results: The provisional equations formulated to calculate N f , the number of free water molecules per unit volume of inorganic and organic solute solutions, respectively, over wide concentration ranges compared well with the calculations of N f using recorded

  3. On the multi-level solution algorithm for Markov chains

    Energy Technology Data Exchange (ETDEWEB)

    Horton, G. [Univ. of Erlangen, Nuernberg (Germany)

    1996-12-31

    We discuss the recently introduced multi-level algorithm for the steady-state solution of Markov chains. The method is based on the aggregation principle, which is well established in the literature. Recursive application of the aggregation yields a multi-level method which has been shown experimentally to give results significantly faster than the methods currently in use. The algorithm can be reformulated as an algebraic multigrid scheme of Galerkin-full approximation type. The uniqueness of the scheme stems from its solution-dependent prolongation operator which permits significant computational savings in the evaluation of certain terms. This paper describes the modeling of computer systems to derive information on performance, measured typically as job throughput or component utilization, and availability, defined as the proportion of time a system is able to perform a certain function in the presence of component failures and possibly also repairs.

  4. Relationship between salivary glucosa levels and salivary pH with candidiasis oral in diabetes mellitus patients

    Directory of Open Access Journals (Sweden)

    Sumintarti Sumintarti

    2016-06-01

    Full Text Available Diabetes Mellitus (DM is a metabolic disease which is characterized by increased blood glucose level and also increased salivary glucose level. The disease is characterized by decreasing pH of the saliva. The decrease pH of saliva can the high risk of oral infection. Candidiasis is the most common infection of patients with diabetes mellitus. The purpose of this study was to determine the relationship between salivary glucose level and salivary pH to the occurrence of oral candidiasis in patients with DM. This type of research is analytic observational study on 30 sample with diabetes mellitus. The determination of salivary glucose level with “GOD PAP test enzymatic calorimetric” and salivary pH with lacmus paper. Oral candidiasis was determined in presenting candida albicans with seeding Saboround agar and gram staining. The result showed r 0'573, which is higher salivary glucose levels, followed by decreasing salivary pH and microscopic examination of candida found in the whole sample of the study. This finding demonstrates that an increased salivary glucose levels and increase salivary pH affect the occurrence of oral candidiasis in diabetic patients.

  5. Exact analytic solutions for Mikheyev-Smirnov-Wolfenstein level crossings

    International Nuclear Information System (INIS)

    Noetzold, D.

    1987-01-01

    An exact formula for the transition probability in level-crossing phenomena is derived for a general case, ranging from adiabatic to sudden crossings. This is done in the context of neutrino flavor oscillations for the Mikheyev-Smirnov-Wolfenstein (MSW) effect, where hitherto only numerical or approximate solutions were obtained. The matter density or level splitting is assumed to be governed by a hyperbolic-tangent function which, however, can change arbitrarily fast between two constant values. For example, in context of the MSW effect this furnishes a nice fit to the solar density determining the level crossing of solar neutrinos. In the quasiadiabatic limit the exact Landau-Zener factor can be read off, correcting some expressions obtained so far. Even in the opposite limit of a sudden level crossing a conversion is found, which can have far-reaching consequences for neutrino detection on Earth

  6. pH effect on pit potential and protection potential of stainless steels AISI-304, 310 and 316 in NaCl solution

    International Nuclear Information System (INIS)

    Cabral, U.Q.; Sathler, L.; Mariano Neto, F.

    1973-06-01

    For three austenitic stainless steels, AISI 304, 310 and 316, the pH influence on the rupture, protection and corrosion potentials was studied in a 0,5N NACl solution. The pit potentials determined by the chronogalvonometric method, are pH independent within the acid range. They showed a rough linear variation within the basic range having a maximum corresponding to the pH value of 8.8. The electrochemical hysteresis method, employed for determining the protection potential, presented a total pH independence for the AISI 316. The other steels showed a small dependence within the basic range but with a tendency for the protection potential to become slightly more active with increasing pH, within the acid range. It was also noted for the three steels studied that the corrosion potental became more active with increasing pH, within the basic range [pt

  7. Conductivity of alanine solution for high level dosimetry

    International Nuclear Information System (INIS)

    Wieser, A.; Figel, M.; Regulla, D.F.

    1993-01-01

    The amino acid alanine is well known as a dosimetric detector material for high level dosimetry. Its application is based on the formation of radicals by ionising radiation. The free radicals are earlier detected by electron spin resonance (ESR) spectroscopy or chemically after dissolving the irradiated samples. Of all these methods the ESR/alanine system is the most advanced and is suggested for reference dosimetry. At present, however, the high cost of the system is a serious handicap for a large scale routine application in radiation plants. In this study the variation of electrical conductivity of L-alanine solution with applied dose is investigated in the range from 0.5-200 kGy. The conductivity was measured with a 50 MHz RF oscillator. This readout method is uncomplicated and may be suitable for routine application. The experiments were performed with L-alanine solution in glass ampoules. (Author)

  8. Normalization of pH level and gastric mucosa after eradication of H. pylori in the remnant stomach.

    Science.gov (United States)

    Kato, Shunji; Matsukura, Norio; Matsuda, Noriko; Tsuchiya, Shinichi; Naito, Zenya; Tajiri, Takashi

    2008-12-01

    The Updated Sydney System (USS) is used to evaluate chronic gastritis and chronic atrophic gastritis (CAG) due to H. pylori infection. Here, we investigated USS scores and gastric juice pH levels in H. pylori infection-positive or -eradicated patients with remnant stomach after surgery. Gastric juice pH levels were measured using pH test-tape in 197 patients (112 H. pylori-positive and 85 H. pylori-negative after eradication) who had undergone distal gastrectomy and conventional H. pylori eradication therapy. In H. pylori infection-positive remnant stomach cases, gastric juice pH showed a reverse correlation with pepsinogen I/II ratio, and H. pylori infection-negative patients following eradication showed associations with the degree of atrophy and intestinal metaplasia at both the anastomosis and in the corpus. Further, pH levels in these patients were normalized time depending after the eradication in the remnant stomach. Eradication therapy for the remnant stomach contributes to the possible improvement of stomach conditions by controlling the pH level of gastric juice. This effect will be protective against the risk of secondary stomach carcinogenesis in the remnant stomach.

  9. Precision sensing by two opposing gradient sensors: how does Escherichia coli find its preferred pH level?

    Science.gov (United States)

    Hu, Bo; Tu, Yuhai

    2013-07-02

    It is essential for bacteria to find optimal conditions for their growth and survival. The optimal levels of certain environmental factors (such as pH and temperature) often correspond to some intermediate points of the respective gradients. This requires the ability of bacteria to navigate from both directions toward the optimum location and is distinct from the conventional unidirectional chemotactic strategy. Remarkably, Escherichia coli cells can perform such a precision sensing task in pH taxis by using the same chemotaxis machinery, but with opposite pH responses from two different chemoreceptors (Tar and Tsr). To understand bacterial pH sensing, we developed an Ising-type model for a mixed cluster of opposing receptors based on the push-pull mechanism. Our model can quantitatively explain experimental observations in pH taxis for various mutants and wild-type cells. We show how the preferred pH level depends on the relative abundance of the competing sensors and how the sensory activity regulates the behavioral response. Our model allows us to make quantitative predictions on signal integration of pH and chemoattractant stimuli. Our study reveals two general conditions and a robust push-pull scheme for precision sensing, which should be applicable in other adaptive sensory systems with opposing gradient sensors. Copyright © 2013 Biophysical Society. Published by Elsevier Inc. All rights reserved.

  10. pH Sensing Properties of Flexible, Bias-Free Graphene Microelectrodes in Complex Fluids: From Phosphate Buffer Solution to Human Serum.

    Science.gov (United States)

    Ping, Jinglei; Blum, Jacquelyn E; Vishnubhotla, Ramya; Vrudhula, Amey; Naylor, Carl H; Gao, Zhaoli; Saven, Jeffery G; Johnson, Alan T Charlie

    2017-08-01

    Advances in techniques for monitoring pH in complex fluids can have a significant impact on analytical and biomedical applications. This study develops flexible graphene microelectrodes (GEs) for rapid (pH of complex biofluids by measuring real-time Faradaic charge transfer between the GE and a solution at zero electrical bias. For an idealized sample of phosphate buffer solution (PBS), the Faradaic current is varied monotonically and systematically with the pH, with a resolution of ≈0.2 pH unit. The current-pH dependence is well described by a hybrid analytical-computational model, where the electric double layer derives from an intrinsic, pH-independent (positive) charge associated with the graphene-water interface and ionizable (negative) charged groups. For ferritin solution, the relative Faradaic current, defined as the difference between the measured current response and a baseline response due to PBS, shows a strong signal associated with ferritin disassembly and the release of ferric ions at pH ≈2.0. For samples of human serum, the Faradaic current shows a reproducible rapid (pH. By combining the Faradaic current and real-time current variation, the methodology is potentially suitable for use to detect tumor-induced changes in extracellular pH. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. Stress corrosion cracking of X80 pipeline steel exposed to high pH solutions with different concentrations of bicarbonate

    Science.gov (United States)

    Fan, Lin; Du, Cui-wei; Liu, Zhi-yong; Li, Xiao-gang

    2013-07-01

    Susceptibilities to stress corrosion cracking (SCC) of X80 pipeline steel in high pH solutions with various concentrations of HCO{3/-} at a passive potential of -0.2 V vs. SCE were investigated by slow strain rate tensile (SSRT) test. The SCC mechanism and the effect of HCO{3/-} were discussed with the aid of electrochemical techniques. It is indicated that X80 steel shows enhanced susceptibility to SCC with the concentration of HCO{3/-} increasing from 0.15 to 1.00 mol/L, and the susceptibility can be evaluated in terms of current density at -0.2 V vs. SCE. The SCC behavior is controlled by the dissolution-based mechanism in these circumstances. Increasing the concentration of HCO{3/-} not only increases the risk of rupture of passive films but also promotes the anodic dissolution of crack tips. Besides, little susceptibility to SCC is found in dilute solution containing 0.05 mol/L HCO{3/-} for X80 steel. This can be attributed to the inhibited repassivation of passive films, manifesting as a more intensive dissolution in the non-crack tip areas than at the crack tips.

  12. The correlation between pH and flow rate of salivary smokers related to nicotine levels labelled on cigarettes

    OpenAIRE

    Saputri, Dewi; Nasution, Abdillah Imron; Surbakti, Mutiara Rizki Wardarni; Gani, Basri A.

    2017-01-01

    Background: Saliva is a biological fluid in oral cavity that plays a role in maintaining the environmental balance and oral commensal. Nicotine of cigarettes has been reported as a predisposing factor for changing of pH and salivary flow rate, thereby changing in biological salivary components. Purpose: This study aimed to analyze the correlation between salivary pH and salivary flow rate in smokers with nicotine levels labeled on cigarettes. Methods: Purposive sampling was conducted involvin...

  13. Effects of cold stratification pretreatment and pH level on ...

    African Journals Online (AJOL)

    Previous studies emphasise that low germination rate of its seed is primarily due to deep seed dormancy. Therefore, studies was done on C. tchihatcheffii seeds, to investigate the effects of cold stratification for different periods (90, 120 and 150 days) and different pH values (pH 6.5, 7.5 and 8.5) on seed germination.

  14. Ph3CCOOSnPh3.Ph3PO AND Ph3CCOOSnPh3.Ph3AsO: SYNTHESIS AND INFRARED STUDY

    Directory of Open Access Journals (Sweden)

    ABDOU MBAYE

    2014-08-01

    Full Text Available The mixture of ethanolic solutions of Ph3CCOOSnPh3 and Ph3PO or Ph3AsO gives Ph3CCOOSnPh3.Ph3PO and Ph3CCOOSnPh3.Ph3AsO adducts which have been characterized by infrared spectroscopy. A discrete structure is suggested for both, the environment around the tin centre being trigonal bipyramidal, the triphenylacetate anion behaving as a mondentate ligand.

  15. The correlation between pH and flow rate of salivary smokers related to nicotine levels labelled on cigarettes

    Directory of Open Access Journals (Sweden)

    Dewi Saputri

    2017-06-01

    Full Text Available Background: Saliva is a biological fluid in oral cavity that plays a role in maintaining the environmental balance and oral commensal. Nicotine of cigarettes has been reported as a predisposing factor for changing of pH and salivary flow rate, thereby changing in biological salivary components. Purpose: This study aimed to analyze the correlation between salivary pH and salivary flow rate in smokers with nicotine levels labeled on cigarettes. Methods: Purposive sampling was conducted involving 40 male smokers. Before participating, they filled a questionnaire related to the history of their smoking habit. Using a spitting method for 5 minutes their saliva was collected. Results: Result of Pearson correlation test showed that there was a significant correlation between smoking intensity and salivary flow rate of those smokers (r = -0.486 and p0.512. There was no correlation between nicotine levels labeled on cigarettes and salivary pH of those smokers (r = -0.216, p>0.181. Nevertheless, there was a significant correlation between salivary flow rate and salivary pH of those smokers (r= 0.686, p<0.00,. Conclusion: There is a strong correlation between the intensity of smoking with salivary flow rate and its pH. However, there is no correlation between nicotine levels labeled on cigarettes and both salivary flow rate as well as salivary pH.

  16. Effect of pH on corrosion behavior of CuCrZr in solution without and with NaCl

    Energy Technology Data Exchange (ETDEWEB)

    Kwok, C.T.; Wong, P.K. [Department of Electromechanical Engineering, University of Macau (China); Man, H.C. [Department of Industrial and Systems Engineering, Hong Kong Polytechnic University (Hong Kong); Cheng, F.T., E-mail: apaftche@polyu.edu.h [Department of Applied Physics, Hong Kong Polytechnic University (Hong Kong)

    2009-10-01

    CuCrZr is a high copper alloy widely used as electrical and thermal conducting material, especially in heat exchangers in nuclear reactors. In this respect, the physical and fatigue properties of CuCrZr have been extensively studied. The electrochemical behavior of CuCrZr, on the other hand, has not been adequately investigated. In the present study, the effect of pH on the corrosion behavior of CuCrZr in aqueous solutions without and with chloride (0.6 M NaCl) was studied. The pH of the solutions is found to exert significant influence on the corrosion behavior of CuCrZr. In acidic solutions without chloride, the corrosion of CuCrZr is ascribed to active dissolution with soluble products. In neutral and alkaline solutions without NaCl, the presence of oxides on the surface of CuCrZr leads to a noble shift in corrosion potential and passivation results in increased corrosion resistance. In chloride solutions at various pH values, the chloride ions influence the formation of the surface layers and the anodic dissolution process during polarization. At high pH, CuCrZr shows significant passivity and high corrosion resistance due to the growth of Cu{sub 2}O/Cu(OH) film which hinders further dissolution whereas at low pH the corrosion resistance is lowered due to active dissolution of Cu.

  17. Effect of pH on corrosion behavior of CuCrZr in solution without and with NaCl

    International Nuclear Information System (INIS)

    Kwok, C.T.; Wong, P.K.; Man, H.C.; Cheng, F.T.

    2009-01-01

    CuCrZr is a high copper alloy widely used as electrical and thermal conducting material, especially in heat exchangers in nuclear reactors. In this respect, the physical and fatigue properties of CuCrZr have been extensively studied. The electrochemical behavior of CuCrZr, on the other hand, has not been adequately investigated. In the present study, the effect of pH on the corrosion behavior of CuCrZr in aqueous solutions without and with chloride (0.6 M NaCl) was studied. The pH of the solutions is found to exert significant influence on the corrosion behavior of CuCrZr. In acidic solutions without chloride, the corrosion of CuCrZr is ascribed to active dissolution with soluble products. In neutral and alkaline solutions without NaCl, the presence of oxides on the surface of CuCrZr leads to a noble shift in corrosion potential and passivation results in increased corrosion resistance. In chloride solutions at various pH values, the chloride ions influence the formation of the surface layers and the anodic dissolution process during polarization. At high pH, CuCrZr shows significant passivity and high corrosion resistance due to the growth of Cu 2 O/Cu(OH) film which hinders further dissolution whereas at low pH the corrosion resistance is lowered due to active dissolution of Cu.

  18. Influence of bismuth oxide concentration on the pH level and biocompatibility of white Portland cement.

    Science.gov (United States)

    Marciano, Marina Angélica; Garcia, Roberto Brandão; Cavenago, Bruno Cavalini; Minotti, Paloma Gagliardi; Midena, Raquel Zanin; Guimarães, Bruno Martini; Ordinola-Zapata, Ronald; Duarte, Marco Antonio Hungaro

    2014-01-01

    To investigate if there is a relation between the increase of bismuth oxide and the decrease of pH levels and an intensification of toxicity in the Portland cement. White Portland cement (WPC) was mixed with 0, 15, 20, 30 and 50% bismuth oxide, in weight. For the pH level test, polyethylene tubes were filled with the cements and immersed in Milli-Q water for 15, 30 and 60 days. After each period, the increase of the pH level was assessed. For the biocompatibility, two polyethylene tubes filled with the cements were implanted in ninety albino rats (n=6). The analysis of the intensity of the inflammatory infiltrate was performed after 15, 30 and 60 days. The statistical analysis was performed using the Kruskal-Wallis, Dunn and Friedman tests for the pH level and the Kruskal-Wallis and Dunn tests for the biological analysis (p0.05). For the inflammatory infiltrates, no significant statistical differences were found among the groups in each period (p>0.05). The 15% WPC showed a significant decrease of the inflammatory infiltrate from 15 to 30 and 60 days (pPortland cement did not affect the pH level and the biological response. The concentration of 15% of bismuth oxide resulted in significant reduction in inflammatory response in comparison with the other concentrations evaluated.

  19. Influence of bismuth oxide concentration on the pH level and biocompatibility of white Portland cement

    Directory of Open Access Journals (Sweden)

    Marina Angélica MARCIANO

    2014-07-01

    Full Text Available Objectives: To investigate if there is a relation between the increase of bismuth oxide and the decrease of pH levels and an intensification of toxicity in the Portland cement. Material and Methods: White Portland cement (WPC was mixed with 0, 15, 20, 30 and 50% bismuth oxide, in weight. For the pH level test, polyethylene tubes were filled with the cements and immersed in Milli-Q water for 15, 30 and 60 days. After each period, the increase of the pH level was assessed. For the biocompatibility, two polyethylene tubes filled with the cements were implanted in ninety albino rats (n=6. The analysis of the intensity of the inflammatory infiltrate was performed after 15, 30 and 60 days. The statistical analysis was performed using the Kruskal-Wallis, Dunn and Friedman tests for the pH level and the Kruskal-Wallis and Dunn tests for the biological analysis (p0.05. For the inflammatory infiltrates, no significant statistical differences were found among the groups in each period (p>0.05. The 15% WPC showed a significant decrease of the inflammatory infiltrate from 15 to 30 and 60 days (p<0.05. Conclusions: The addition of bismuth oxide into Portland cement did not affect the pH level and the biological response. The concentration of 15% of bismuth oxide resulted in significant reduction in inflammatory response in comparison with the other concentrations evaluated.

  20. Radiolytic gas formation in high-level liquid waste solutions

    International Nuclear Information System (INIS)

    Brodda, B.-G.; Dix, Siegfried; Merz, E.R.

    1989-01-01

    High-level fission product waste solutions originating from the first-cycle raffinate stream of spent fast breeder reactor fuel reprocessing have been investigated gas chromatographically for their radiolytic and chemical gas production. The solutions showed considerable formation of hydrogen, carbon dioxide and dinitrogen oxide, whereas atmospheric oxygen was consumed completely within a short time. In particular, carbon dioxide resulted from the radiolytic degradation of entrained organic solvent. After nearly complete degradation of the organic solvent, the influence of hydrazine and nitrogen dioxide on hydrogen formation was investigated. Hydrazinium hydroxide led to the formation of dinitrogen oxide and nitrogen. After 60 d, the concentration of dinitrogen oxide had reduced to zero, whereas the amount of nitrogen formed had reached a maximum. This may be explained by simultaneous chemical and radiolytic reactions leading to the formation of dinitrogen oxide and nitrogen and photolytic fission of dinitrogen oxide. Addition of sodium nitrite resulted in the rapid formation of dinitrogen oxide. The rate of hydrogen production was not changed significantly after the addition of hydrazine or nitrite. The results indicate that under normal operating conditions no dangerous hydrogen radiolysis yields should develop in the course of reprocessing and high-level liquid waste tank storage. Organic entrainment may lead to enhanced radiolytic decomposition and thus to considerable hydrogen production rates and pressure build-up in closed systems. (author)

  1. Tuning interionic interaction by rationally controlling solution pH for highly selective colorimetric sensing of arginine.

    Science.gov (United States)

    Qian, Qin; Hao, Jie; Ma, Wenjie; Yu, Ping; Mao, Lanqun

    2016-04-01

    Direct selective sensing of arginine in central nervous systems remains very essential to understanding of the molecular basis of some physiological events. This study presents the first demonstration on a simple yet effective method for arginine sensing with gold nanoparticles (Au-NPs) as the signal readout. The rationale for the method is based on the pH-dependent feature of the interionic interaction between cysteine and arginine. At pH 6.0, cysteine can only interact with arginine through the ion-pair interaction and such interaction can lead to the changes in both the solution color and UV-vis spectrum of the cysteine-protected Au-NPs upon the addition of arginine. These changes are further developed into an analytical strategy for effective sensing of arginine by rationally controlling the pH values of Au-NP dispersions with the ratio of the absorbance at 650 nm (A 650) to that at 520 nm (A 520) (A 650/A 520) as a parameter for analysis. The method is responsive to arginine without the interference from other species in the cerebral system; under the optimized conditions, the A 650/A 520 values are linear with the concentration of arginine within a concentration range from 0.80 to 64 μM, yet remain unchanged with the addition of other kinds of amino acids or the species in the central nervous system into the Au-NPs dispersion containing cysteine. The method demonstrated here is reliable and robust and could thus be used for detection of the increase of arginine in central nervous systems.

  2. Kinetic Rate Law Parameter Measurements on a Borosilicate Waste Glass: Effect of Temperature, pH, and Solution Composition on Alkali Ion Exchange

    International Nuclear Information System (INIS)

    Pierce, Eric M.; McGrail, B PETER.; Icenhower, J P.; Rodriguez, Elsa A.; Steele, Jackie L.; Baum, Steven R.

    2004-01-01

    The reaction kinetics of glass is controlled by matrix dissolution and ion exchange (IEX). Dissolution of an alkali-rich simulated borosilicate waste glass was investigated using single-pass flow-through (SPFT) experiments. Experiments were conducted as a function of temperature, pH, and solution composition by varying the SiO 2 (aq) activity in the influent solution. Results showed that under dilute conditions matrix dissolution increased with increasing pH and temperature, and decreased with increasing SiO 2 (aq) activity. IEX rates decreased with increasing pH and temperature, and increased with increasing SiO 2 (aq) activity. Over the solution composition range interrogated in this study the dominant dissolution mechanism changed from matrix dissolution to IEX. These results suggest that ''secondary'' reactions may become dominant under certain environmental conditions and emphasize the need to incorporate these reactions into dissolution rate models

  3. Estimation of Hydrazine Decomposition on Measuring the High-Temperature pH in Hydrazine/ETA Solutions at 553 K

    International Nuclear Information System (INIS)

    Hwang, Jae Sik; Yeon, Jei Won; Yun, Myung Hee; Song, Kyu Seok; Lee, Sang Ill

    2010-01-01

    Hydrazine is one of the most excellent oxygen scavengers used in the secondary circuit of nuclear power plants. Furthermore, in some pants, the hydrazine is used as a source of hydrogen required to suppress radiolysis of the coolant water in the primary loop. When hydrazine was exposed in the high temperature and high pressure water, it can be decomposed into the various products such as NH 3 , N 2 , H 2 , and NO 3 ions. As the result, the pH of solution containing hydrazine in the condition of the high temperature and high pressure can be changed by those decomposed products. In the present work, we investigated the decomposition behavior of hydrazine in ETA (ethanol amine) solution. In addition, we measured the high temperature pH at 553 K on the various hydrazine/ETA solutions for confirming the applicability of the yttria stabilized zirconia (YSZ)- based pH electrode in secondary circuit of the nuclear power plants

  4. Gravity-driven pH adjustment for site-specific protein pKa measurement by solution-state NMR

    Science.gov (United States)

    Li, Wei

    2017-12-01

    To automate pH adjustment in site-specific protein pKa measurement by solution-state NMR, I present a funnel with two caps for the standard 5 mm NMR tube. The novelty of this simple-to-build and inexpensive apparatus is that it allows automatic gravity-driven pH adjustment within the magnet, and consequently results in a fully automated NMR-monitored pH titration without any hardware modification on the NMR spectrometer.

  5. Gamma radiation and osmotic potential of the nutrient solution differentially affect macronutrient concentrations, pH and EC in chilhuacle pepper fruits

    International Nuclear Information System (INIS)

    Victor Garcia-Gaytan, Libia Iris Trejo-Tellez; Olga Tejeda-Sartorius; Maribel Ramirez-Martinez; Julian Delgadillo-Martinez; Fernando Carlos Gomez-Merino; Soledad Garcia-Morales

    2018-01-01

    Chilhuacle pepper (Capsicum annuum L.) seeds were exposed to gamma radiation (GR) doses (0, 10, 80 and 120 Gy), and plants were grown in hydroponics with different osmotic potentials (OP) (- 0.036, - 0.072, - 0.092, and - 0.108 MPa) in the nutrient solution. We measured the nutrient concentrations, pH and electrical conductivity (EC) in fruits at different time points after transplanting (70, 90 and 130 dat), and found the GR, nutrient solution OP and their interactions differentially affected N, P, K, Ca, and Mg concentrations, as well as pH and EC in chilhuacle peppers. (author)

  6. Soil solution Zn and pH dynamics in non-rhizosphere soil and in the rhizosphere of Thlaspi caerulescens grown in a Zn/Cd-contaminated soil.

    Science.gov (United States)

    Luo, Y M; Christie, P; Baker, A J

    2000-07-01

    Temporal changes in soil solution properties and metal speciation were studied in non-rhizosphere soil and in the rhizosphere of the hyperaccumulator Thlaspi caerulescens J. & C. Presl (population from Prayon, Belgium) grown in a Zn- and Cd-contaminated soil. This paper focuses on soil solution Zn and pH dynamics during phytoextraction. The concentration of Zn in both non-rhizosphere and rhizosphere soil solutions decreased from 23 mg/l at the beginning to 2 mg/l at the end of the experiment (84 days after transplanting of seedlings), mainly due to chemical sorption. There was no significant difference in overall Zn concentration between the planted and the unplanted soil solutions (P > 0.05). Soil solution pH decreased initially and then increased slightly in both planted and unplanted soil zones. From 60 to 84 days after transplanting, the pH of the rhizosphere soil solution was higher than that of non-rhizosphere soil solution (P<0.05). Zn uptake by the hyperaccumulator plants was 8.8 mg per pot (each containing 1 kg oven-dry soil) on average. The data indicate that the potential of T. caerulescens to remove Zn from contaminated soil may not be related to acidification of the rhizosphere.

  7. The influence of surface modification, coating agents and pH value of aqueous solutions on physical properties of magnetite nanoparticles investigated by ESR method

    Energy Technology Data Exchange (ETDEWEB)

    Dobosz, Bernadeta, E-mail: benia@amu.edu.pl [Medical Physics Division, Faculty of Physics, Adam Mickiewicz University, Umultowska 85, 61-614 Poznań (Poland); Krzyminiewski, Ryszard [Medical Physics Division, Faculty of Physics, Adam Mickiewicz University, Umultowska 85, 61-614 Poznań (Poland); Kurczewska, Joanna; Schroeder, Grzegorz [Faculty of Chemistry, Adam Mickiewicz University, Umultowska 89B, 61-614 Poznań (Poland)

    2017-05-01

    The article presents the results of electron spin resonance (ESR) studies for aqueous solutions of functionalized superparamagnetic iron(II,III) oxide nanoparticles. The samples studied differed in type of organic ligands at the magnetite surface, type of coating agent and pH value of aqueous solutions. The ESR spectra of the samples were obtained at room temperature and at 230 K. The field cooling (FC) experiment was performed for selected samples, and the effective anisotropy field (H{sub K2}) and the first order magnetocrystalline anisotropy constant (K{sub 1}) was calculated. The process of the nanoparticles diffusion in different environments (human blood, human serum) forced by an inhomogeneous magnetic field was monitored and their interactions with different solvents have been discussed. It has been shown that ESR method is useful to observe the impact of organic ligands at the magnetite surface, type of coating agent and pH value of aqueous solutions on the properties of iron(II,III) oxide nanoparticles. - Highlights: • The influence of different organic ligands, coatings and pH values of aqueous solutions on the physical properties of the magnetite nanoparticles studied by ESR method. • Nanoparticles diffusion forced by inhomogeneous magnetic field monitored by ESR and explained. • A narrow line separated in ESR spectra by CREM. • The influence of different coatings and pH values of aqueous solutions on ESR spectra of TEMPO attached to the magnetite core.

  8. Tetrachloroethylene Removal Rate from Aqueous Solutions by Pumice Doped with Copper: An Evaluation of the Effect of pH

    Directory of Open Access Journals (Sweden)

    Ali Almasi

    2016-12-01

    Full Text Available Tetrachloroethylene (TCE is a chlorinated aliphatic hydrocarbon, used in many industries. Effective and efficient treatment of industrial wastewater, containing TCE, is one of the environmental requirements. The purpose of this study was to determine the role of alkaline environments in TCE removal rate from aqueous solutions, using copper-doped pumice. This experimental study was performed, using granulated pumice stones with a mesh 4 (8.4 mm in alkaline conditions; the samples were coated with copper. Copper-doped pumice was prepared as a bed at doses of 1, 2, and 3 g/L; the study was performed at pH ranges of 3, 7, and 11. Based on the results, copper-doped pumice showed good efficacy in TCE removal; in addition, its performance increased in alkaline conditions. Therefore, use of this stone for the treatment of wastewater, containing TCE, is effective due to its availability and low cost. Besides, it can be considered a good option, given its high efficiency in the absorption process.

  9. Calculation of the equilibrium pH in a multiple-buffered aqueous solution based on partitioning of proton buffering: a new predictive formula.

    Science.gov (United States)

    Nguyen, Minhtri K; Kao, Liyo; Kurtz, Ira

    2009-06-01

    Upon the addition of protons to an aqueous solution containing multiple buffers, the final H+ concentration ([H+]) at equilibrium is determined by the partitioning of added H+ among the various buffer components. In the analysis of acid-base chemistry, the Henderson-Hasselbalch equation and the Stewart strong ion formulation can only describe (rather than predict) the equilibrium pH following a proton load since these formulas calculate the equilibrium pH only when the reactant concentrations at equilibrium(1) 1The term "equilibrium" refers to the steady state proton and reactant concentrations when the buffering of excess protons by the various buffers is complete. are already known. In this regard, it is simpler to directly measure the equilibrium pH rather than measure the equilibrium reactant concentrations to calculate the equilibrium pH. As these formulas cannot predict the final equilibrium [H+] following a proton load to a multiple-buffered aqueous solution, we developed a new quantitative approach for predicting the equilibrium [H+] that is based on the preequilibrium(2)2 The term "preequilibrium" refers to the initial proton and reactant concentrations immediately upon addition of protons and before the buffering of excess protons by the various buffers. concentrations of all buffers in an aqueous solution. The mathematical model used to derive our equation is based on proton transfer buffer equilibria without requiring the incorporation of electroneutrality considerations. The model consists of a quartic polynomial equation that is derived based solely on the partitioning of H+ among the various buffer components. We tested the accuracy of the model using aqueous solutions with various buffers and measured the equilibrium pH values following the addition of HCl. Our results confirmed the accuracy of our new equation (r2 = 1; measured pH vs. predicted pH), indicating that it quantitatively accounts for the underlying acid-base phenomenology.

  10. Calculation of the equilibrium pH in a multiple-buffered aqueous solution based on partitioning of proton buffering: a new predictive formula

    Science.gov (United States)

    Nguyen, Minhtri K.; Kao, Liyo; Kurtz, Ira

    2009-01-01

    Upon the addition of protons to an aqueous solution containing multiple buffers, the final H+ concentration ([H+]) at equilibrium is determined by the partitioning of added H+ among the various buffer components. In the analysis of acid-base chemistry, the Henderson-Hasselbalch equation and the Stewart strong ion formulation can only describe (rather than predict) the equilibrium pH following a proton load since these formulas calculate the equilibrium pH only when the reactant concentrations at equilibrium1 1The term “equilibrium” refers to the steady state proton and reactant concentrations when the buffering of excess protons by the various buffers is complete. are already known. In this regard, it is simpler to directly measure the equilibrium pH rather than measure the equilibrium reactant concentrations to calculate the equilibrium pH. As these formulas cannot predict the final equilibrium [H+] following a proton load to a multiple-buffered aqueous solution, we developed a new quantitative approach for predicting the equilibrium [H+] that is based on the preequilibrium22The term “preequilibrium” refers to the initial proton and reactant concentrations immediately upon addition of protons and before the buffering of excess protons by the various buffers. concentrations of all buffers in an aqueous solution. The mathematical model used to derive our equation is based on proton transfer buffer equilibria without requiring the incorporation of electroneutrality considerations. The model consists of a quartic polynomial equation that is derived based solely on the partitioning of H+ among the various buffer components. We tested the accuracy of the model using aqueous solutions with various buffers and measured the equilibrium pH values following the addition of HCl. Our results confirmed the accuracy of our new equation (r2 = 1; measured pH vs. predicted pH), indicating that it quantitatively accounts for the underlying acid-base phenomenology. PMID

  11. Methods of pH determination in Calcareous soils of Oman: The effect of Electrolyte and soil solution ratio

    International Nuclear Information System (INIS)

    Al-Busaidi, A.; Cookson, P.

    2002-01-01

    Determination of pH assists in understanding many reactions that occur in soil. Soil pH values are highly sensitive to the procedure used for determination. In this study, pH was measured in different electrolytes [distilled water (pHw), 0.01MCaCl2 (pHCa), 1MKCl (pHk), and 0.01MBaCl2 (pHba)] with different soil: electrolyte ratios (i.e. 1:1, 1:2.5 and 1:5). The objective was to determine the effect of each electrolyte and dilution ratio on pH of saline and non-saline soils from Oman. It was found that ph values varied significantly between electrolytes and with different dilution ratios. Linear regression equations were generated between electrolytes, dilution ratios and were mostly significant. Soil pH values determined in different electrolytes were significantly interrelated. Water appeared as a highly suitable solvent for soil pH measurements because it is simple and values familiar to soil users. However, alkaline errors and electrode instabilities due to liquid junction and soluble salt effects, affected soil pH measurements, especially in water, and resulted in alkaline errors during pH measurements. Errors were minimized when pH was measured in electrolytes rather than in water. (author)

  12. Science PhD career preferences: levels, changes, and advisor encouragement.

    Directory of Open Access Journals (Sweden)

    Henry Sauermann

    Full Text Available Even though academic research is often viewed as the preferred career path for PhD trained scientists, most U.S. graduates enter careers in industry, government, or "alternative careers." There has been a growing concern that these career patterns reflect fundamental imbalances between the supply of scientists seeking academic positions and the availability of such positions. However, while government statistics provide insights into realized career transitions, there is little systematic data on scientists' career preferences and thus on the degree to which there is a mismatch between observed career paths and scientists' preferences. Moreover, we lack systematic evidence whether career preferences adjust over the course of the PhD training and to what extent advisors exacerbate imbalances by encouraging their students to pursue academic positions. Based on a national survey of PhD students at tier-one U.S. institutions, we provide insights into the career preferences of junior scientists across the life sciences, physics, and chemistry. We also show that the attractiveness of academic careers decreases significantly over the course of the PhD program, despite the fact that advisors strongly encourage academic careers over non-academic careers. Our data provide an empirical basis for common concerns regarding labor market imbalances. Our results also suggest the need for mechanisms that provide PhD applicants with information that allows them to carefully weigh the costs and benefits of pursuing a PhD, as well as for mechanisms that complement the job market advice advisors give to their current students.

  13. Science PhD career preferences: levels, changes, and advisor encouragement.

    Science.gov (United States)

    Sauermann, Henry; Roach, Michael

    2012-01-01

    Even though academic research is often viewed as the preferred career path for PhD trained scientists, most U.S. graduates enter careers in industry, government, or "alternative careers." There has been a growing concern that these career patterns reflect fundamental imbalances between the supply of scientists seeking academic positions and the availability of such positions. However, while government statistics provide insights into realized career transitions, there is little systematic data on scientists' career preferences and thus on the degree to which there is a mismatch between observed career paths and scientists' preferences. Moreover, we lack systematic evidence whether career preferences adjust over the course of the PhD training and to what extent advisors exacerbate imbalances by encouraging their students to pursue academic positions. Based on a national survey of PhD students at tier-one U.S. institutions, we provide insights into the career preferences of junior scientists across the life sciences, physics, and chemistry. We also show that the attractiveness of academic careers decreases significantly over the course of the PhD program, despite the fact that advisors strongly encourage academic careers over non-academic careers. Our data provide an empirical basis for common concerns regarding labor market imbalances. Our results also suggest the need for mechanisms that provide PhD applicants with information that allows them to carefully weigh the costs and benefits of pursuing a PhD, as well as for mechanisms that complement the job market advice advisors give to their current students.

  14. SPATIAL AND TEMPORAL PATTERN OF SOIL pH AND Eh AND THEIR IMPACT ON SOLUTE IRON CONTENT IN A WETLAND (TRANSDANUBIA, HUNGARY

    Directory of Open Access Journals (Sweden)

    SZALAI ZOLTÁN

    2008-06-01

    Full Text Available Land mosaics have direct and indirect influence on chemical reaction and redox condition of soils. The present paper deals with the relationship between some environmental factors (such as soil andvegetation patterns, micro-relief, water regime, temperature and incident solar radiation and the pH, Eh of soils and solute iron in a headwater wetland in Transdanubia, Hungary. Measurements have been taken in four different patches and along their boundaries: sedge (Carex vulpina, Carex riparia, three patches and two species, horsetail (Equisetum arvense, common nettle (Urtica dioica. Thespatial pattern of the studied parameters are influenced by the water regime, micro-topography, climatic conditions and by direct and indirect effects of vegetation. The indirect effect can be the shading, which has influence on soil temperature and on the incident solar radiation (PAR. Root respiration and excretion of organic acids appear as direct effects.. There have been measured individual pH and Eh characteristic in the studied patches. Soil Eh, pH and solute iron have shown seasonal dynamics. Higher redox potentials (increasingly oxidative conditions and higher pH values were measured between late autumn and early spring. The increasing physiological activity of plants causes lower pH and Eh and it leads to higher spatial differences. Although temperature is an essential determining factor for Eh and pH, but our results suggest it rather has indirect effectsthrough plants on wetlands.

  15. The study on the pH behavior of the HFSC leached solution. The development of model considering the pozzolanic reaction

    International Nuclear Information System (INIS)

    Yoshida, Yasushi; Mihara, Morihiro

    2005-09-01

    The development of low alkalinity cement (high fly-ash contained silica-fume cement, HFSC) has been carried out in JNC. Low alkalinity for this cement is achieved by adding pozzolan materials to ordinary portland cement and Ca ion attributed to high alkalinity is consumed by forming CHS gel. This report shows the calculation model to predict the composition for HFSC reacted solution which considers cement mineral dissolution/precipitation as equilibrium reactions and dissolution for pozzolan material as a kinetic reaction. The dissolution kinetic equation for pozzolan material is also derived from leaching experiment. This calculation model is applied to the leaching experiment where powdered HFSC was reacted with distilled water. As a result of comparison between calculation and experimental measurement at the early stage for leaching the tendency for pH, pH decrease from 12.5 to 11.5 drastically, could be interpreted by this calculation model, however, after this drastic pH decreasing pH predicted by calculation model also shows drastic decrease whereas pH for experiment decreased mildly around pH 11.5. It could be thought that this difference between experiment and calculation is caused by inappropriate modelling for CSH gel dissolution/precipitation of C/S value lower than 1.0. For this C/S range thermodynamic data for intermediate and end member for solid solution for CSH gel and in addition the reaction kinetic for CSH gel should be examined in detail. (author)

  16. Impact of Initial pH and Pyrolysis Temperature on the Adsorption of Cr(Ⅵ from Aqueous Solutions on Corn Straw-based Materials

    Directory of Open Access Journals (Sweden)

    WANG Shuai

    2016-09-01

    Full Text Available Batch experiments were performed on Cr(Ⅵ adsorption using four straw-based materials including corn straw and three kinds of biochar pyrolysed at 300 ℃, 450 ℃ and 600 ℃, respectively. The results showed that the Cr(Ⅵ adsorption were significantly affected by initial pH and pyrolysis temperature. The data were described by kinetic and isotherm models, and showed that the adsorption of Cr(Ⅵ was increased with the decrease of initial pH. The removal rates of Cr(Ⅵ were decreased with the increase of the pyrolysis temperature at pH=3 or pH=5. The biochar pyrolysed at 300 ℃ had the best capability of removing Cr(Ⅵ from aqueous solution at pH=1, and the maxi-mum adsorption quantity was 141.24 mg·g-1 approximately. It observed that both the lower initial pH and the lower pyrolysis temperature had positive effects on the removal of Cr(Ⅵ from aqueous solution.

  17. Contribution of solution pH and buffer capacity to suppress intergranular stress corrosion cracking of sensitized type 304 stainless steel at 95 C

    International Nuclear Information System (INIS)

    Zhang, S.; Shibata, T.; Haruna, T.

    1999-01-01

    Controlling pH of high-temperature water to ∼pH 7 at 300 C by adding lithium hydroxide (LiOH) into the coolant system of a pressurized water reactor (PWR) successfully has been mitigating the corrosion of PWR component materials. The effects of solution pH and buffer capacity on intergranular stress corrosion cracking (IGSCC) of sensitized type 304 stainless steel ([SS] UNS S30400) was examined at 95 C by slow strain rate technique (SSRT) with an in-situ cracking observation system. It was found that an increase in solution pH or buffer capacity increased crack initiation time and decreased mean crack initiation frequency, but exerted almost no effect on crack propagation. This inhibition effect on IGSCC initiation was explained as resulting from a retarding effect of solution pH and buffer capacity on the decrease in pH at crack nuclei caused by the hydrolysis of metal ions dissolved when the passive film was ruptured by strain in SSRT

  18. Influence of alkaline (PH 8.3-12.0) and saline solutions on chemical, mineralogical and physical properties of two different bentonites - batch experiments at 25 deg. C

    International Nuclear Information System (INIS)

    Heikola, Tiina; Vuorinen, Ulla; Kumpulainen, Sirpa; Kiviranta, Leena; Korkeakoski, Petri

    2012-01-01

    Document available in extended abstract form only. Construction of a spent fuel repository deep in the bedrock will need supporting structures using cement materials. A part of them can be removed before closure but still it is estimated that about 1000 tonnes will remain in the host rock. Degradation of cementitious materials produces leachates of high pH. If such an alkaline plume reaches the bentonite buffer, it may induce mineralogical and chemical changes in bentonite over long term, and further affect the safety functions of the buffer. Laboratory experiments were done with the objective to gain data of possible alterations in mineralogical, chemical and physical properties of bentonites contacted with high-pH saline solutions. Two untreated, high grade, Na- and Ca-bentonites, were used in batch experiments, which were carried out in an anaerobic glove-box at 25±1 deg. C for 554 days. Each bentonite sample (20 g) was leached with approximately 3.8 L of leaching solution, which equals 190 mL/g of bentonite. The bentonites were leached with three types of simulated cement waters (pH 9.7, 11.3 and 12.0) and one saline groundwater simulate (pH 8.3) as a reference. The leaching solutions were 0.3 M, and contained NaCl and CaCl 2 , and trace amounts of SiO 2 , K, Br, Mg and SO 4 . Dissolved oxygen and carbon dioxide were removed from leaching solutions before mixing of bentonite in PC bottles. The samples were placed on a platform shaker in order to allow better contact between bentonite and the leaching solution. The evolution of pH in the samples was followed by measuring the pH-value of each sample in the solution phase approximately twice a week and the solution was renewed when values of two to three consecutive measurements did not change. On average, the leaching solution was renewed once a month. For each renewal of the leaching solution the phases were separated, the reacted solution withdrawn, and the chemical composition analysed. Before analysis the

  19. Food web analysis reveals effects of pH on mercury bioaccumulation at multiple trophic levels in streams

    Energy Technology Data Exchange (ETDEWEB)

    Jardine, Timothy D., E-mail: tim.jardine@usask.ca [Canadian Rivers Institute and Department of Biology, University of New Brunswick, Saint John, NB E2L 4L5 (Canada); Kidd, Karen A. [Canadian Rivers Institute and Department of Biology, University of New Brunswick, Saint John, NB E2L 4L5 (Canada); O’ Driscoll, Nelson [Department of Earth and Environmental Sciences, Acadia University, Wolfville, NS B4P 2R6 (Canada)

    2013-05-15

    Highlights: ► We examine biomagnification of Hg through stream food webs using δ15 N. ► Slopes of methyl Hg vs. trophic level were higher than total Hg vs. trophic level. ► Biomagnification from predatory insects to fish was related to pH of the water. ► Biomagnification at lower trophic levels was related to dietary concentrations. ► These trends can explain variation in field-measured Hg in food webs. -- Abstract: Biomagnification processes and the factors that govern them, including those for mercury (Hg), are poorly understood in streams. Total and methyl Hg concentrations and relative trophic position (using δ{sup 15}N) were analyzed in biofilm and invertebrates from 21 streams in New Brunswick, Canada to assess food web biomagnification leading to the common minnow blacknose dace (Rhinichthys atratulus), a species known to have Hg concentrations that are higher in low pH waters. Biomagnification slopes within stream food webs measured using Hg vs. δ{sup 15}N or corresponding trophic levels (TL) differed depending on the chemical species analyzed, with total Hg exhibiting increases of 1.3–2.5 per TL (mean slope of total Hg vs. δ{sup 15}N = 0.14 ± 0.06 S.D., range = 0.06–0.20) and methyl Hg showing a more pronounced increase of 2.8 to 6.0 per TL (mean slope of methyl Hg vs. δ{sup 15}N = 0.30 ± 0.08 S.D., range = 0.22–0.39). While Hg biomagnification slopes through the entire food web (Trophic Magnification Factors, TMFs) were not influenced by water chemistry (pH), dietary concentrations of methyl Hg strongly influenced biomagnification factors (BMFs) for consumer-diet pairs within the food web at lower trophic levels, and BMFs between dace and predatory invertebrates were significantly higher in low pH waters. These analyses, coupled with observations of higher Hg in primary producers in streams with low pH, suggest that pH influences both baseline concentrations and biomagnification of Hg in these systems. Because higher Hg

  20. Food web analysis reveals effects of pH on mercury bioaccumulation at multiple trophic levels in streams

    International Nuclear Information System (INIS)

    Jardine, Timothy D.; Kidd, Karen A.; O’ Driscoll, Nelson

    2013-01-01

    Highlights: ► We examine biomagnification of Hg through stream food webs using δ15 N. ► Slopes of methyl Hg vs. trophic level were higher than total Hg vs. trophic level. ► Biomagnification from predatory insects to fish was related to pH of the water. ► Biomagnification at lower trophic levels was related to dietary concentrations. ► These trends can explain variation in field-measured Hg in food webs. -- Abstract: Biomagnification processes and the factors that govern them, including those for mercury (Hg), are poorly understood in streams. Total and methyl Hg concentrations and relative trophic position (using δ 15 N) were analyzed in biofilm and invertebrates from 21 streams in New Brunswick, Canada to assess food web biomagnification leading to the common minnow blacknose dace (Rhinichthys atratulus), a species known to have Hg concentrations that are higher in low pH waters. Biomagnification slopes within stream food webs measured using Hg vs. δ 15 N or corresponding trophic levels (TL) differed depending on the chemical species analyzed, with total Hg exhibiting increases of 1.3–2.5 per TL (mean slope of total Hg vs. δ 15 N = 0.14 ± 0.06 S.D., range = 0.06–0.20) and methyl Hg showing a more pronounced increase of 2.8 to 6.0 per TL (mean slope of methyl Hg vs. δ 15 N = 0.30 ± 0.08 S.D., range = 0.22–0.39). While Hg biomagnification slopes through the entire food web (Trophic Magnification Factors, TMFs) were not influenced by water chemistry (pH), dietary concentrations of methyl Hg strongly influenced biomagnification factors (BMFs) for consumer-diet pairs within the food web at lower trophic levels, and BMFs between dace and predatory invertebrates were significantly higher in low pH waters. These analyses, coupled with observations of higher Hg in primary producers in streams with low pH, suggest that pH influences both baseline concentrations and biomagnification of Hg in these systems. Because higher Hg concentrations in the diets

  1. pH variation and influence in an autotrophic nitrogen removing biofilm system using an efficient numerical solution strategy

    DEFF Research Database (Denmark)

    Vangsgaard, Anna Katrine; Mauricio Iglesias, Miguel; Valverde Perez, Borja

    2013-01-01

    A pH simulator consisting of an efficient numerical solver of a system of nine nonlinear equations was constructed and implemented in the modeling software MATLAB. The pH simulator was integrated in a granular biofilm model and used to simulate the pH profiles within granules performing...... the nitritation-anammox process for a range of operating points. The simulation results showed that pH profiles were consistently increasing with increasing depth into the granule, since the proton producing aerobic ammonium oxidizers (AOB) were located close to the granule surface.Despite this pH profile, more...... NH3 was available for AOB than for anaerobic ammonium oxidizers (AnAOB), located in the center of the granules. However, operating at a higher oxygen loading resulted in steeper changes in pH over the depth of the granule and caused the NH3 concentration profile to increase from the granule surface...

  2. Transport and Retention of TiO2 Rutile Nanoparticles in Saturated Porous Media: Influence of Solution pH, Ionic Strength, and the Presence of Humic Acid

    Science.gov (United States)

    The influence of solution pH, ionic strength, and varying concentrations of the Suwannee River Humic Acid (SRHA) on the transport of titanium dioxide (TiO2, rutile) nanoparticle aggregates (nTiO2) in saturated porous media was investigated through systematically examining the tra...

  3. Role of Metal Cations on the corrosion behaviour of 8090-T851 in a pH 2.0 solution

    DEFF Research Database (Denmark)

    Murthy, K.S.N.; Ambat, Rajan; Dwarakadasa, E.S.

    1994-01-01

    The influence of cations such as Cu2+, Al3+ and Li+ on the corrosion behaviour of 8090-T851(Al-Li) alloy in a pH 2.0 HCl solution was investigated by weight loss and polarisation techniques. Weight loss experiments showed that the effect of cation is a strong function of its nature...

  4. Pharmacodynamics of nitrofurantoin at different pH levels against pathogens involved in urinary tract infections

    NARCIS (Netherlands)

    Fransen, F.; Melchers, M.J.B.; Lagarde, C.M.C.; Meletiadis, J.; Mouton, J.W.

    2017-01-01

    Background: Urinary tract infections are among the most common human infections. Due to the progressive increase in ESBL-producing bacteria and the unavailability of new antibiotics, re-evaluation of 'old' antibiotics is needed. However, the pharmacodynamics of nitrofurantoin under variable pH

  5. Initial dissolution rate of a Japanese simulated high-level waste glass P0798 as a function of pH and temperature measured by using micro-channel flow-through test method

    International Nuclear Information System (INIS)

    Inagaki, Yaohiro; Makigaki, Hikaru; Idemitsu, Kazuya; Arima, Tatsumi; Mitsui, Sei-ichiro; Noshita, Kenji

    2012-01-01

    Aqueous dissolution tests were performed for a Japanese type of simulated high-level waste (HLW) glass P0798 by using a newly developed test method of micro-channel flow-through (MCFT) method, and the initial dissolution rate of glass matrix, r 0 , was measured as a function of solution pH (3-11) and temperature (25-90degC) precisely and consistently for systematic evaluation of the dissolution kinetics. The MCFT method using a micro-channel reactor with a coupon shaped glass specimen has the following features to provide precise and consistent data on the glass dissolution rate: (1) any controlled constant solution condition can be provided over the test duration; (2) the glass surface area actually reacting with solution can be determined accurately; and (3) direct and totally quantitative analyses of the reacted glass surface can be performed for confirming consistency of the test results. The present test results indicated that the r 0 shows a 'V-shaped' pH dependence with a minimum at around pH 6 at 25degC, but it changes to a 'U-shaped' one with a flat bottom at neutral pH at elevated temperatures of up to 90degC. The present results also indicated that the r 0 increases with temperature according to an Arrhenius law at any pH, and the apparent activation energy evaluated from Arrhenius relation increases with pH from 54 kJ/mol at pH 3 to 76 kJ/mol at pH 10, which suggests that the dissolution mechanism changes depending on pH. (author)

  6. The passivation of calcite by acid mine water. Column experiments with ferric sulfate and ferric chloride solutions at pH 2

    Energy Technology Data Exchange (ETDEWEB)

    Soler, Josep M. [Institute of Earth Sciences ' Jaume Almera' (CSIC), Lluis Sole i Sabaris s/n, 08028 Barcelona, Catalonia (Spain); Institute of Environmental Assessment and Water Research (CSIC), Jordi Girona 18, 08034 Barcelona, Catalonia (Spain)], E-mail: jsoler@ija.csic.es; Boi, Marco [Institute of Earth Sciences ' Jaume Almera' (CSIC), Lluis Sole i Sabaris s/n, 08028 Barcelona, Catalonia (Spain); Institute of Environmental Assessment and Water Research (CSIC), Jordi Girona 18, 08034 Barcelona, Catalonia (Spain); Mogollon, Jose Luis [Institute of Earth Sciences ' Jaume Almera' (CSIC), Lluis Sole i Sabaris s/n, 08028 Barcelona, Catalonia (Spain); Instituto de Ciencias de la Tierra, Universidad Central de Venezuela, Caracas 1020-A (Venezuela, Bolivarian Republic of); Cama, Jordi; Ayora, Carlos [Institute of Earth Sciences ' Jaume Almera' (CSIC), Lluis Sole i Sabaris s/n, 08028 Barcelona, Catalonia (Spain); Institute of Environmental Assessment and Water Research (CSIC), Jordi Girona 18, 08034 Barcelona, Catalonia (Spain); Nico, Peter S.; Tamura, Nobumichi; Kunz, Martin [Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 94720 (United States)

    2008-12-15

    Column experiments, simulating the behavior of passive treatment systems for acid mine drainage, have been performed. Acid solutions (HCl or H{sub 2}SO{sub 4}, pH 2), with initial concentrations of Fe(III) ranging from 250 to 1500 mg L{sup -1}, were injected into column reactors packed with calcite grains at a constant flow rate. The composition of the solutions was monitored during the experiments. At the end of the experiments (passivation of the columns), the composition and structure of the solids were measured. The dissolution of calcite in the columns caused an increase in pH and the release of Ca into the solution, leading to the precipitation of gypsum and Fe-oxyhydroxysulfates (Fe(III)-SO{sub 4}-H{sup +} solutions) or Fe-oxyhydroxychlorides (Fe(III)-Cl-H{sup +} solutions). The columns worked as an efficient barrier for some time, increasing the pH of the circulating solutions from 2 to {approx}6-7 and removing its metal content. However, after some time (several weeks, depending on the conditions), the columns became chemically inert. The results showed that passivation time increased with decreasing anion and metal content of the solutions. Gypsum was the phase responsible for the passivation of calcite in the experiments with Fe(III)-SO{sub 4}-H{sup +} solutions. Schwertmannite and goethite appeared as the Fe(III) secondary phases in those experiments. Akaganeite was the phase responsible for the passivation of the system in the experiments with Fe(III)-Cl-H{sup +} solutions.

  7. Collection and storage of red blood cells with anticoagulant and additive solution with a physiologic pH

    NARCIS (Netherlands)

    Burger, Patrick; Korsten, Herbert; Verhoeven, Arthur J.; de Korte, Dirk; van Bruggen, Robin

    2012-01-01

    BACKGROUND: A donation of whole blood is most commonly collected in acidic citrate-phosphate-dextrose (CPD) variants with pH 5.2 to 6.2 as anticoagulants. Previously, we have shown that the initial pH after red blood cell (RBC) preparation can have an effect on RBCs during storage. First, we

  8. PhD Crisis Discourse: A Critical Approach to the Framing of the Problem and Some Australian "Solutions"

    Science.gov (United States)

    Cuthbert, Denise; Molla, Tebeje

    2015-01-01

    A feature of HE reform discourse is the tendency to construct the rationale for reform in terms of averting calamity and risk. We refer to this risk talk as "crisis discourse." This study examines the formulation of PhD crisis discourse internationally and in Australia. We find that a key feature of PhD crisis discourse is that…

  9. pH variation and influence in an autotrophic nitrogen removing biofilm system using an efficient numerical solution strategy.

    Science.gov (United States)

    Vangsgaard, Anna Katrine; Mauricio-Iglesias, Miguel; Valverde-Pérez, Borja; Gernaey, Krist V; Sin, Gürkan

    2013-01-01

    A pH simulator consisting of an efficient numerical solver of a system of nine nonlinear equations was constructed and implemented in the modeling software MATLAB. The pH simulator was integrated in a granular biofilm model and used to simulate the pH profiles within granules performing the nitritation-anammox process for a range of operating points. The simulation results showed that pH profiles were consistently increasing with increasing depth into the granule, since the proton-producing aerobic ammonium-oxidizing bacteria (AOB) were located close to the granule surface. Despite this pH profile, more NH3 was available for AOB than for anaerobic ammonium oxidizers, located in the center of the granules. However, operating at a higher oxygen loading resulted in steeper changes in pH over the depth of the granule and caused the NH3 concentration profile to increase from the granule surface towards the center. The initial value of the background charge and influent bicarbonate concentration were found to greatly influence the simulation result and should be accurately measured. Since the change in pH over the depth of the biofilm was relatively small, the activity potential of the microbial groups affected by the pH did not change more than 5% over the depth of the granules.

  10. Fate of cadmium at the soil-solution interface: a thermodynamic study as influenced by varying pH at South 24 Parganas, West Bengal, India.

    Science.gov (United States)

    Karak, Tanmoy; Paul, Ranjit Kumar; Das, Sampa; Das, Dilip K; Dutta, Amrit Kumar; Boruah, Romesh K

    2015-11-01

    A study on the sorption kinetics of Cd from soil solution to soils was conducted to assess the persistence of Cd in soil solution as it is related to the leaching, bioavailability, and potential toxicity of Cd. The kinetics of Cd sorption on two non-contaminated alkaline soils from Canning (22° 18' 48.02″ N and 88° 39' 29.0″ E) and Lakshmikantapur (22° 06' 16.61″ N and 88° 19' 08.66″ E) of South 24 Parganas, West Bengal, India, were studied using conventional batch experiment. The variable soil suspension parameters were pH (4.00, 6.00, 8.18, and 9.00), temperatures (308, 318, and 328 K) and Cd concentrations (5-100 mg L(-1)). The average rate coefficient (kavg) and half-life (t1/2) values indicate that the persistence of Cd in soil solution is influenced by both temperature and soil suspension pH. The concentration of Cd in soil solution decreases with increase of temperature; therefore, Cd sorption on the soil-solution interface is an endothermic one. Higher pH decreases the t 1/2 of Cd in soil solution, indicating that higher pH (alkaline) is not a serious concern in Cd toxicity than lower pH (acidic). Based on the energy of activation (Ea) values, Cd sorption in acidic pH (14.76±0.29 to 64.45±4.50 kJ mol(-1)) is a surface control phenomenon and in alkaline pH (9.33±0.09 to 44.60±2.01 kJ mol(-1)) is a diffusion control phenomenon The enthalpy of activation (ΔH∓) values were found to be between 7.28 and 61.73 kJ mol(-1). Additionally, higher positive energy of activation (ΔG∓) values (46.82±2.01 to 94.47±2.36 kJ mol(-1)) suggested that there is an energy barrier for product formation.

  11. Effect of surface chemistry, solution pH, and ionic strength on the removal of herbicides diuron and amitrole from water by an activated carbon fiber.

    Science.gov (United States)

    Fontecha-Cámara, M A; López-Ramón, M V; Alvarez-Merino, M A; Moreno-Castilla, C

    2007-01-30

    A study was conducted on the effects of carbon surface chemistry, solution pH, and ionic strength on the removal of diuron and amitrole from aqueous solutions by adsorption on an as-received and oxidized activated carbon fiber. Results obtained were explained by the surface characteristics of the adsorbents and the characteristics of the herbicide molecules. Under the experimental conditions used, diuron uptake was much higher than that of amitrole, despite its larger molecular dimensions, due to the lesser water solubility, greater hydrophobicity, and larger dipolar moment of diuron compared with amitrole. Uptake variations associated with differences in carbon surface oxidation, solution pH, and ionic strength were explained by corresponding changes in electrostatic, hydrophobic, and van der Waals interactions.

  12. Influence of the solution pH in the 6-mercaptopurine self-assembled monolayer (6MP-SAM) on a Au(111) single-crystal electrode.

    Science.gov (United States)

    Madueño, Rafael; García-Raya, Daniel; Viudez, Alfonso J; Sevilla, José M; Pineda, Teresa; Blázquez, Manuel

    2007-10-23

    Self-assembled monolayers (SAMs) of 6-mercaptopurine (6MP) have been prepared on a Au(111) single-crystal electrode by immersion of the metal surface in a 100 microM 6MP and 0.01 M HClO4 solution. The 6MP-SAM Au(111) single-crystal electrodes were transferred to the cell and allowed to equilibrate with the different aqueous working solutions before the electrochemical experiments. The influence of the solution pH was studied by cyclic voltammetry, double layer capacitance curves, and electrochemical impedance spectroscopy. The electrochemical behavior of the 6MP-SAM in acetic acid at pH 4 presents important differences in comparison to that obtained in 0.1 M KOH solutions. Cyclic voltammograms for the reductive desorption process in acid medium are broad and show some features that can be explained by a phase transition between a chemisorbed and a physisorbed state of the 6MP molecules. The low solubility of these molecules in acid medium could explain this phenomenon and the readsorption of the complete monolayer when the potential is scanned in the positive direction. The variation of the double-layer capacitance values in the potential range of monolayer stability with the pH suggests that the acid-base chemistry of the 6MP molecules is playing a role. This fact has been studied by following the variations of the electron-transfer rate constant of the highly charged redox probes as are Fe(CN)(6)-3/-4 and Ru(NH3)(6)+3/+2 as a function of solution pH. The apparent surface pKa value for the 6MP-SAM (pKa approximately 8) is explained by the total conversion of the different 6MP tautomers that exist in solution to the thiol species in the adsorbed state.

  13. Effects of EDTA on the electronic properties of passive film formed on Fe-20Cr in pH 8.5 buffer solution

    International Nuclear Information System (INIS)

    Cho, Eun Ae; Kwon, Hyuk Sang; Beranrd, Frederic

    2003-01-01

    The electronic properties of the passive film formed on Fe-20Cr ferritic stainless steel in pH 8.5 buffer solution containing 0.05 M EDTA (ethylene diammine tetraacetic acid) were examined by the photocurrent measurements and Mott-Schottky analysis for the film. XPS depth profile for the film demonstrated that Cr content in the outermost layer of the passive film was higher in the solution with EDTA than that in the solution without EDTA, due to selective dissolution of Fe by EDTA. In the solution with EDTA, the passive film showed characteristics of an amorphous or highly disordered n-type semiconductor. The band gap energies of the passive film are estimated to be ∼ 3.0 eV, irrespective of film formation potential from 0 to 700 mV SCE and of presence of EDTA. However, the donor density of the passive film formed in the solution with EDTA is much higher than that formed in the solution without EDTA, due to an increase in oxygen vacancy resulted from the dissolution of Fe-oxide in the outermost layer of the passive film. These results support the proposed model that the passive film formed on Fe-20Cr in pH 8.5 buffer solution mainly consists of Cr-substituted γ-Fe 2 O 3

  14. Passivation Characteristics of Alloy Corrosion-Resistant Steel Cr10Mo1 in Simulating Concrete Pore Solutions: Combination Effects of pH and Chloride.

    Science.gov (United States)

    Ai, Zhiyong; Sun, Wei; Jiang, Jinyang; Song, Dan; Ma, Han; Zhang, Jianchun; Wang, Danqian

    2016-09-01

    The electrochemical behaviour for passivation of new alloy corrosion-resistant steel Cr10Mo1 immersed in alkaline solutions with different pH values (13.3, 12.0, 10.5, and 9.0) and chloride contents (0.2 M and 1.0 M), was investigated by various electrochemical techniques: linear polarization resistance, electrochemical impedance spectroscopy and capacitance measurements. The chemical composition and structure of passive films were determined by XPS. The morphological features and surface composition of the immersed steel were evaluated by SEM together with EDS chemical analysis. The results evidence that pH plays an important role in the passivation of the corrosion-resistant steel and the effect is highly dependent upon the chloride contents. In solutions with low chloride (0.2 M), the corrosion-resistant steel has notably enhanced passivity with pH falling from 13.3 to 9.0, but does conversely when in presence of high chloride (1.0 M). The passive film on the corrosion-resistant steel presents a bilayer structure: an outer layer enriched in Fe oxides and hydroxides, and an inner layer, rich in Cr species. The film composition varies with pH values and chloride contents. As the pH drops, more Cr oxides are enriched in the film while Fe oxides gradually decompose. Increasing chloride promotes Cr oxides and Fe oxides to transform into their hydroxides with little protection, and this is more significant at lower pH (10.5 and 9.0). These changes annotate passivation characteristics of the corrosion-resistant steel in the solutions of different electrolyte.

  15. The electrochemical behaviour of stainless steel AISI 304 in alkaline solutions with different pH in the presence of chlorides

    International Nuclear Information System (INIS)

    Freire, L.; Carmezim, M.J.; Ferreira, M.G.S.; Montemor, M.F.

    2011-01-01

    Highlights: → The passivation and passivation breakdown of AISI 304 in alkaline solutions with different pH was studied. → The electrochemical behaviour and the corrosion resistance in chloride environments were evaluated using d.c. potentiodynamic polarization and electrochemical impedance spectroscopy. → The results were modelled using a hierarchically distributed circuit and revealed a more susceptible surface at pH 9. → The passive film characterization was carried out by SEM and EDS analysis, revealing the existence of MnS inclusions and the increase of Cr/Fe ratio in the attacked areas, preferably the vicinity of those inclusions. - Abstract: Nowadays, stainless steel reinforcements appear as an effective solution to increase the durability of reinforced concrete structures exposed to very aggressive environments. AISI 304 is widely used for this purpose. Although the improved durability of reinforcing AISI 304, when compared to carbon steel, there is a high probability of pitting susceptibility in the presence of chlorides. Thus, the present work aims at studying the passivation and passivation breakdown of AISI 304 in alkaline solutions of different pH (pH from 13 to 9), simulating the interstitial concrete electrolyte. These solutions were contaminated with different concentrations of chloride ions (3% and 10%, as NaCl). The electrochemical behaviour was evaluated by d.c. potentiodynamic polarization and by electrochemical impedance spectroscopy (EIS). The morphological features and the changes observed in the surface composition were evaluated by Scanning Electron Microscopy (SEM) together with EDS chemical analysis. The results evidence that pH plays an important role in the evolution of the film resistance and charge transfer processes. Moreover, the effect is highly dependent upon the chloride content and immersion time.

  16. Removal of radiocobalt from aqueous solutions by kaolinite affected by solid content, pH, ionic strength, contact time and temperature

    International Nuclear Information System (INIS)

    Kan Li; Zhengjie Liu; Lei Chen; Yunhui Dong; Jun Hu; Chinese Academy of Sciences, Hefei

    2013-01-01

    The kaolinite sample was characterized by Fourier transform infrared spectroscopy (FT-IR) and X-ray powder diffraction, and was applied as adsorbent for the removal of radiocobalt ions from radioactive wastewater. The results demonstrated that the sorption of Co(II) was strongly dependent on pH and ionic strength at low pH values, and independent of pH and ionic strength at high pH values. The sorption of Co(II) was dominated by outer-sphere surface complexation or ion exchange at low pH values, whereas inner-sphere surface complexation was the main sorption mechanism at high pH values. The sorption isotherms were well described by Langmuir, Freundlich and Dubinin-Radushkevich models. The thermodynamic parameters (i.e., ΔGdeg, ΔSdeg, ΔHdeg) calculated from the temperature-dependent sorption isotherms indicated that the sorption of Co(II) on kaolinite was an endothermic and spontaneous process. The results of high sorption capacity of kaolinite suggested that the kaolinite sample was a suitable material for the preconcentration of Co(II) from large volumes of aqueous solutions and as backfill materials in nuclear waste management. (author)

  17. pH sensing in aqueous solutions using a MnO2 thin film electrodeposited on a glassy carbon electrode

    International Nuclear Information System (INIS)

    Cherchour, N.; Deslouis, C.; Messaoudi, B.; Pailleret, A.

    2011-01-01

    An electrolysis technique at a constant potential was used to develop a highly reproducible and fast elaboration method of adherent manganese dioxide thin films on a glassy carbon electrode from aqueous solutions containing sulfuric acid and manganese sulfate. The resulting films were found to have a nanostructured character presumably due rather to birnessite (δ-MnO 2 ) than to γ-MnO 2 , as suggested by their Raman and XRD signatures. They lead to modified electrodes that present an obvious although complex pH dependent potentiometric response. This sensor indeed showed a single slope non-Nernstian linear behaviour over the 1.5-12 pH range for increasing pH direction ('trace'), whereas a Nernstian two slopes linear behaviour was observed for decreasing pH direction ('re-trace'). Preliminary EIS experiments carried out at a pH value of 1.8 seem to reveal a sensitivity mechanism based on proton insertion process at least at highly acidic pH values.

  18. pH sensing in aqueous solutions using a MnO{sub 2} thin film electrodeposited on a glassy carbon electrode

    Energy Technology Data Exchange (ETDEWEB)

    Cherchour, N. [Laboratoire de Technologie des Materiaux et Genie des Procedes (LTMGP), Departement de Genie des Procedes, Universite A. Mira, Route de Targa Ouzemmour, 06000 Bejaia (Algeria); CNRS, UPR 15, Laboratoire Interfaces et Systemes Electrochimiques (LISE, case courrier 133), 4 Place Jussieu, F-75005 Paris (France); UPMC Univ. Paris VI, UPR 15, Laboratoire Interfaces et Systemes Electrochimiques (LISE, case courrier 133), 4 Place Jussieu, F-75005 Paris (France); Deslouis, C. [CNRS, UPR 15, Laboratoire Interfaces et Systemes Electrochimiques (LISE, case courrier 133), 4 Place Jussieu, F-75005 Paris (France); UPMC Univ. Paris VI, UPR 15, Laboratoire Interfaces et Systemes Electrochimiques (LISE, case courrier 133), 4 Place Jussieu, F-75005 Paris (France); Messaoudi, B. [Laboratoire de Technologie des Materiaux et Genie des Procedes (LTMGP), Departement de Genie des Procedes, Universite A. Mira, Route de Targa Ouzemmour, 06000 Bejaia (Algeria); Pailleret, A., E-mail: alain.pailleret@upmc.fr [CNRS, UPR 15, Laboratoire Interfaces et Systemes Electrochimiques (LISE, case courrier 133), 4 Place Jussieu, F-75005 Paris (France); UPMC Univ. Paris VI, UPR 15, Laboratoire Interfaces et Systemes Electrochimiques (LISE, case courrier 133), 4 Place Jussieu, F-75005 Paris (France)

    2011-11-30

    An electrolysis technique at a constant potential was used to develop a highly reproducible and fast elaboration method of adherent manganese dioxide thin films on a glassy carbon electrode from aqueous solutions containing sulfuric acid and manganese sulfate. The resulting films were found to have a nanostructured character presumably due rather to birnessite ({delta}-MnO{sub 2}) than to {gamma}-MnO{sub 2}, as suggested by their Raman and XRD signatures. They lead to modified electrodes that present an obvious although complex pH dependent potentiometric response. This sensor indeed showed a single slope non-Nernstian linear behaviour over the 1.5-12 pH range for increasing pH direction ('trace'), whereas a Nernstian two slopes linear behaviour was observed for decreasing pH direction ('re-trace'). Preliminary EIS experiments carried out at a pH value of 1.8 seem to reveal a sensitivity mechanism based on proton insertion process at least at highly acidic pH values.

  19. Binding of sodium dodecyl sulfate with linear and branched polyethyleneimines in aqueous solution at different pH values.

    Science.gov (United States)

    Wang, Hao; Wang, Yilin; Yan, Haike; Zhang, Jin; Thomas, Robert K

    2006-02-14

    Isothermal titration microcalorimetry (ITC), conductivity, and turbidity measurements have been carried out to study the interaction of sodium dodecyl sulfate (SDS) with polyethyleneimines (PEI) including linear PEI and branched PEI at different pH values of 3, 7, and 10. In all cases, the polymers show a remarkable affinity toward SDS. At pH 3, the polymer PEI is a strong polycation, and the binding is dominated by electrostatic 1:1 charge neutralization with the anionic surfactant. At pH 7, the electrostatic attraction between SDS and PEI is weak, and the hydrophobic interaction becomes stronger. At the natural pH of 10, PEI is essentially nonionic and binds SDS in the form of polymer-bound surfactant aggregates. The charge neutralization concentration (C1) of SDS for the PEI-SDS complex can be derived from the curves of variation of the enthalpy, conductivity, and turbidity with SDS concentration. There is good agreement between the results from the three methods and all show a decrease with increasing pH. The total interaction enthalpies (deltaH(total)) of PEI with SDS are obtained from the observed enthalpy curves and the difference enthalpy (deltaH*) between the total enthalpy of branched PEI with SDS, and the total enthalpy of linear PEI with SDS can be derived from the obtained deltaH(total). The difference deltaH* increases dramatically as pH increases, which indicates that the interactions are different for linear PEI and branched PEI at high pH values. A schematic map of the different states of aggregation is presented.

  20. Parameters affecting level measurement interpretation of nuclear fuel solutions

    International Nuclear Information System (INIS)

    Hunt, B.A.; Landat, D.A.

    1999-01-01

    This paper describes a level measurement technique commonly used in the measurement of radioactive liquids and equipment utilised by the inspectors for safeguards purposes. Some of the influencing parameters affecting the measurement results by this technique are characterised. An essential requisite for successful process operations in chemical facilities involving liquids generally require some physical measurements to be made in-line for both process and quality control in order to achieve the necessary final product specifications . In nuclear fuel reprocessing facilities, the same objectives apply coupled however with an additional requirement of achieving nuclear material accountancy and control. In view of the strategic importance of some of the process vessels in nuclear facilities, accountancy has to be supported by volume and density measurements of low uncertainty. Inspectors therefore require instruments which are at the very least as good as or better than operator's equipment. The classical measurement technique and most widely applied for process liquids in nuclear installations is the bubbler probe or dip-tube technique. Here a regulated flow of air passes through tubes inserted to various depths into the vessel and pressure readings are measured which are a function of the presence of liquid height and density of solution in the tank. These readings, taken together with a pre-determined calibration curve are sufficient for the volume and amount of liquor in a tank to be quantified. All measurement equipment and instrumentation are long distances from the tank environment. The key physical parameter to measure at this location is therefore pressure. Equipment designed developed, commissioned and tested in the tank measurement facilities at Ispra and in nuclear installations in Europe, Japan and the USA, house digital pressure transducer modules with manufacture's declared features of better than 0.01% accuracy and long term stability of 0.01% full

  1. Effect of the pH in the adsorption and in the immersion enthalpy of monohydroxylated phenols from aqueous solutions on activated carbons.

    Science.gov (United States)

    Blanco-Martínez, D A; Giraldo, L; Moreno-Piraján, J C

    2009-09-30

    An activated carbon Carbochem--PS230 was modified by chemical and thermal treatment in flow of H(2) in order to evaluate the influence of the activated carbon chemical surface in the adsorption of the monohydroxylated phenols. The solid-solution interaction was determined by analyzing the adsorption isotherms at 298 K at pH 7, 9 and 11 during 48 h. The adsorption capacity of activated carbons increases when the pH solution decreases. The amount adsorbed increases in the reduced carbon at the maximum adsorption pH and decreases in the oxidized carbon. In the sample of granulated activated carbon, CAG, the monohydroxylated phenols adsorption capacity diminishes in the following order catechol >hydroquinone >resorcinol, at the three pH values. The experimental data are evaluated with Freundlich's and Langmuir's models. The immersion enthalpies are determined and increase with the retained amount, ranging between 21.5 and 45.7 J g(-1). In addition, the immersion enthalpies show more interaction with the reduced activated carbon that has lower total acidity contents.

  2. Semi-mechanistic partial buffer approach to modeling pH, the buffer properties, and the distribution of ionic species in complex solutions.

    Science.gov (United States)

    Dougherty, Daniel P; Da Conceicao Neta, Edith Ramos; McFeeters, Roger F; Lubkin, Sharon R; Breidt, Frederick

    2006-08-09

    In many biological science and food processing applications, it is very important to control or modify pH. However, the complex, unknown composition of biological media and foods often limits the utility of purely theoretical approaches to modeling pH and calculating the distributions of ionizable species. This paper provides general formulas and efficient algorithms for predicting the pH, titration, ionic species concentrations, buffer capacity, and ionic strength of buffer solutions containing both defined and undefined components. A flexible, semi-mechanistic, partial buffering (SMPB) approach is presented that uses local polynomial regression to model the buffering influence of complex or undefined components in a solution, while identified components of known concentration are modeled using expressions based on extensions of the standard acid-base theory. The SMPB method is implemented in a freeware package, (pH)Tools, for use with Matlab. We validated the predictive accuracy of these methods by using strong acid titrations of cucumber slurries to predict the amount of a weak acid required to adjust pH to selected target values.

  3. Electrochemical Corrosion Behavior of Carbon Steel and Hot Dip Galvanized Steel in Simulated Concrete Solution with Different pH Values

    Directory of Open Access Journals (Sweden)

    Wanchen XIE

    2017-08-01

    Full Text Available Hot dip galvanizing technology is now widely used as a method of protection for steel rebars. The corrosion behaviors of Q235 carbon steel and hot galvanized steel in a Ca(OH2 solution with a pH from 10 to 13 was investigated by electrode potential and polarization curves testing. The results indicated that carbon steel and hot galvanized steel were all passivated in a strong alkaline solution. The electrode potential of hot dip galvanized steel was lower than that of carbon steel; thus, hot dip galvanized steel can provide very good anodic protection for carbon steel. However, when the pH value reached 12.5, a polarity reversal occurred under the condition of a certain potential. Hot dip galvanized coating became a cathode, and the corrosion of carbon steel accelerated. The electrochemical behaviors and passivation abilities of hot dip galvanized steel and carbon steel were affected by pH. The higher the pH value was, the more easily they were passivated.DOI: http://dx.doi.org/10.5755/j01.ms.23.3.16675

  4. Study of the crystallographic phase change on copper (I) selenide thin films prepared through chemical bath deposition by varying the pH of the solution

    Energy Technology Data Exchange (ETDEWEB)

    Sandoval-Paz, M.G., E-mail: myrnasandoval@udec.cl [Departament of Physics, Faculty of Physical Sciences and Mathematics, University of Concepcion, Box 160-C, Concepción (Chile); Rodríguez, C.A. [Department of Materials Engineering, Faculty of Engineering, University of Concepción, Edmundo Larenas 270, Concepción 4070409 (Chile); Porcile-Saavedra, P.F. [Departament of Physics, Faculty of Physical Sciences and Mathematics, University of Concepcion, Box 160-C, Concepción (Chile); Trejo-Cruz, C. [Department of Physics, Faculty of Science, University of Biobío, Avenue Collao 1202, Box 5C, Concepción 4051381 (Chile)

    2016-07-15

    Copper (I) selenide thin films with orthorhombic and cubic structure were deposited on glass substrates by using the chemical bath deposition technique. The effects of the solution pH on the films growth and subsequently the structural, optical and electrical properties of the films were studied. Films with orthorhombic structure were obtained from baths wherein both metal complex and hydroxide coexist; while films with cubic structure were obtained from baths where the metal hydroxide there is no present. The structural modifications are accompanied by changes in bandgap energy, morphology and electrical resistivity of the films. - Graphical abstract: “Study of the crystallographic phase change on copper (I) selenide thin films prepared through chemical bath deposition by varying the pH of the solution” by M. G. Sandoval-Paz, C. A. Rodríguez, P. F. Porcile-Saavedra, C. Trejo-Cruz. Display Omitted - Highlights: • Copper (I) selenide thin films were obtained by chemical bath deposition. • Orthorhombic to cubic phase change was induced by varying the reaction solution pH. • Orthorhombic phase is obtained mainly from a hydroxides cluster mechanism. • Cubic phase is obtained mainly from an ion by ion mechanism. • Structural, optical and electrical properties are presented as a function of pH.

  5. Ni removal from aqueous solutions by chemical reduction: Impact of pH and pe in the presence of citrate

    International Nuclear Information System (INIS)

    Li, Chi-Wang; Yu, Jui-Hsuan; Liang, Yang-Min; Chou, Yi-Hsuan; Park, Hyung-June; Choo, Kwang-Ho; Chen, Shiao-Shing

    2016-01-01

    The chemical precipitation of Ni ions from industrial wastewater at alkaline pH values creates waste chemical sludge (e.g., Ni(OH)_2). We herein focused on Ni removal via chemical reduction using dithionite, by converting Ni(II) to its elemental or other valuable forms. Without the presence of a chelator (e.g., citrate), the nickel reduction efficiency increased with increasing dithionite:Ni molar ratio, reaching 99% at ratios above 3:1. The effect of pH on Ni reduction was in agreement with the standard redox potentials (pe"0) of dithionite, which became more negative with an increase in pH leading to greater Ni reduction efficiencies. With the formation of Ni-citrate chelates, however, the Ni reduction deteriorated. Elevated pH and temperature improved nickel reduction, due to the greater reducing power of dithionite. The optimal pH value for Ni(II) reduction was found to be 8. Injecting Cu seed particles enhanced the rate and amount of Ni reduced. NiS and Ni_3S_2 were identified in the crystal of the resulting solids by X-ray crystallography, and the presence of elemental Ni was explained by X-ray photoelectron spectroscopy. The chemical reduction of actual printed circuit board wastewater with the dithionite:Ni(II) molar ratio dose of 12:1 retrieved 99% nickel after 30-min reaction at 40 °C.

  6. Ni removal from aqueous solutions by chemical reduction: Impact of pH and pe in the presence of citrate

    Energy Technology Data Exchange (ETDEWEB)

    Li, Chi-Wang, E-mail: chiwang@mail.tku.edu.tw [Department of Water Resources and Environmental Engineering, Tamkang University, No. 151 Yingzhuan Road, Tamsui District, New Taipei City, 25137, Taiwan (China); Yu, Jui-Hsuan [Department of Water Resources and Environmental Engineering, Tamkang University, No. 151 Yingzhuan Road, Tamsui District, New Taipei City, 25137, Taiwan (China); Department of Marine Leisure and Tourism, Taipei College of Maritime Technology, No. 150, Sec. 3, Binhai Road, Tamsui District, New Taipei City, 251, Taiwan (China); Liang, Yang-Min; Chou, Yi-Hsuan [Department of Water Resources and Environmental Engineering, Tamkang University, No. 151 Yingzhuan Road, Tamsui District, New Taipei City, 25137, Taiwan (China); Park, Hyung-June [Department of Environmental Engineering, Kyungpook National University, 80 Daehak-ro, Buk-gu, Daegu, 41566 (Korea, Republic of); Choo, Kwang-Ho, E-mail: chookh@knu.ac.kr [Department of Environmental Engineering, Kyungpook National University, 80 Daehak-ro, Buk-gu, Daegu, 41566 (Korea, Republic of); Chen, Shiao-Shing [Institute of Environmental Engineering and Management, National Taipei University of Technology, No. 1, Sec. 3, Chung-Hsiao E. Road, Taipei, 106, Taiwan (China)

    2016-12-15

    The chemical precipitation of Ni ions from industrial wastewater at alkaline pH values creates waste chemical sludge (e.g., Ni(OH){sub 2}). We herein focused on Ni removal via chemical reduction using dithionite, by converting Ni(II) to its elemental or other valuable forms. Without the presence of a chelator (e.g., citrate), the nickel reduction efficiency increased with increasing dithionite:Ni molar ratio, reaching 99% at ratios above 3:1. The effect of pH on Ni reduction was in agreement with the standard redox potentials (pe{sup 0}) of dithionite, which became more negative with an increase in pH leading to greater Ni reduction efficiencies. With the formation of Ni-citrate chelates, however, the Ni reduction deteriorated. Elevated pH and temperature improved nickel reduction, due to the greater reducing power of dithionite. The optimal pH value for Ni(II) reduction was found to be 8. Injecting Cu seed particles enhanced the rate and amount of Ni reduced. NiS and Ni{sub 3}S{sub 2} were identified in the crystal of the resulting solids by X-ray crystallography, and the presence of elemental Ni was explained by X-ray photoelectron spectroscopy. The chemical reduction of actual printed circuit board wastewater with the dithionite:Ni(II) molar ratio dose of 12:1 retrieved 99% nickel after 30-min reaction at 40 °C.

  7. Aggregation and metal-complexation behaviour of THPP porphyrin in ethanol/water solutions as function of pH

    Science.gov (United States)

    Zannotti, Marco; Giovannetti, Rita; Minofar, Babak; Řeha, David; Plačková, Lydie; D'Amato, Chiara A.; Rommozzi, Elena; Dudko, Hanna V.; Kari, Nuerguli; Minicucci, Marco

    2018-03-01

    The effect of pH change on 5,10,15,20-Tetrakis(4-hydroxyphenyl)-21H,23H-porphine (THPP) with its aggregation as function of water-ethanol mixture was studied with UV-vis, fluorescence, Raman and computational analysis. In neutral pH, THPP was present as free-base and, increasing the water amount, aggregation occurred with the formation of H- and J-aggregates. The aggregation constant and the concentration of dimers were calculated, other information about the dimer aggregation were evaluated by computational study. In acidic pH, by the insertions of two hydrogens in the porphyrin rings, the porphyrin changed its geometry with a ring deformation confirmed by red-shifted spectrum and quenching in fluorescence; at this low pH, increasing the water amount, the acidic form (THPPH2)2 + resulted more stable due to a polar environment with stronger interaction by hydrogen bonding. In basic pH, reached by NH4OH, THPP porphyrin was able to react with alkali metals in order to form sitting-atop complex (M2THPP) confirmed by the typical absorption spectrum of metallo-porphyrin, Raman spectroscopy and by computational analysis.

  8. Effects of sodium hypochlorite and high pH buffer solution in electrokinetic soil treatment on soil chromium removal and the functional diversity of soil microbial community

    International Nuclear Information System (INIS)

    Cang Long; Zhou Dongmei; Alshawabkeh, Akram N.; Chen Haifeng

    2007-01-01

    Effects of sodium hypochlorite (NaClO), applied as an oxidant in catholyte, and high pH buffer solution on soil Cr removal and the functional diversity of soil microbial community during enhanced electrokinetic treatments of a chromium (Cr) contaminated red soil are evaluated. Using pH control system to maintain high alkalinity of soil together with the use of NaClO increased the electrical conductivities of soil pore liquid and electroosmotic flux compared with the control (Exp-01). The pH control and NaClO improved the removal of Cr(VI) and total Cr from the soil. The highest removal percentages of soil Cr(VI) and total Cr were 96 and 72%, respectively, in Exp-04 when the pH value of the anolyte was controlled at 10 and NaClO was added in the catholyte. The alkaline soil environment and introduction of NaClO in the soil enhanced the desorption of Cr(VI) from the soil and promoted Cr(III) oxidation to mobile Cr(VI), respectively. However, the elevated pH and introduction of NaClO in the soil, which are necessary for improving the removal efficiency of soil Cr, resulted in a significantly adverse impact on the functional diversity of soil microbial community. It suggests that to assess the negative impact of extreme conditions for enhancing the extraction efficiencies of Cr on the soil properties and function is necessary

  9. Influence of the pH value of a colloidal gold solution on the absorption spectra of an LSPR-assisted sensor

    International Nuclear Information System (INIS)

    Zhu, Jin; Li, Wenbin; Zhu, Mao; Zhang, Wei; Niu, Wencheng; Liu, Guohua

    2014-01-01

    The localized surface plasmon resonances (LSPRs) of gold particles assembled on a crystal plate are a powerful tool for biological sensors. Here, we prepare gold colloids in different pH solutions. We monitor the effects of the particle radius and particle coverage on the absorption spectra of AT-cut (r-face dihedral angle of about 3°) crystal plates supporting gold nanoparticles. The surface morphologies were monitored on silicon dioxide substrates using ultraviolet and visible (UV-vis) spectroscopy, and atomic force microscopy (AFM). The results showed that the gold particle coverage decreases with increasing pH value of the gold colloid solution. This phenomenon demonstrates that self-assembled gold surfaces were formed via the electrostatic adsorption of gold particles on the positively charged, ionized amino groups on the crystal plates in the acidic solution. The spectrum of gold nanoparticles with different coverage degree on the crystal plates showed that the LSPR properties are highly dependent on pH

  10. Modified atmosphere packaging for prevention of mold spoilage of bakery products with different pH and water activity levels.

    Science.gov (United States)

    Guynot, M E; Marín, S; Sanchis, V; Ramos, A J

    2003-10-01

    A sponge cake analog was used to study the influence of pH, water activity (aw), and carbon dioxide (CO2) levels on the growth of seven fungal species commonly causing bakery product spoilage (Eurotium amstelodami, Eurotium herbariorum, Eurotium repens, Eurotium rubrum, Aspergillus niger, Aspergillus flavus, and Penicillium corylophilum). A full factorial design was used. Water activity, CO2, and their interaction were the main factors significantly affecting fungal growth. Water activity at levels of 0.80 to 0.90 had a significant influence on fungal growth and determined the concentration of CO2 needed to prevent cake analog spoilage. At an aw level of 0.85, lag phases increased twofold when the level of CO2 in the headspace increased from 0 to 70%. In general, no fungal growth was observed for up to 28 days of incubation at 25 degrees C when samples were packaged with 100% CO2, regardless of the aw level. Partial least squares projection to latent structures regression was used to build a polynomial model to predict sponge cake shelf life on the basis of the lag phases of all seven species tested. The model developed explained quite well (R2 = 79%) the growth of almost all species, which responded similarly to changes in tested factors. The results of this study emphasize the importance of combining several hurdles, such as modified atmosphere packaging, aw, and pH, that have synergistic or additive effects on the inhibition of mold growth.

  11. Diffusion of flexible, charged, nanoscopic molecules in solution: Size and pH dependence for PAMAM dendrimer

    Science.gov (United States)

    Maiti, Prabal K.; Bagchi, Biman

    2009-12-01

    In order to understand self-diffusion (D) of a charged, flexible, and porous nanoscopic molecule in water, we carry out very long, fully atomistic molecular dynamics simulation of PAMAM dendrimer up to eight generations in explicit salt water under varying pH. We find that while the radius of gyration (Rg) varies as N1/3, the self-diffusion constant (D ) scales, surprisingly, as N-α, with α =0.39 at high pH and 0.5 at neutral pH, indicating a dramatic breakdown of Stokes-Einstein relation for diffusion of charged nanoscopic molecules. The variation in D as a function of radius of gyration demonstrates the importance of treating water and ions explicitly in the diffusion process of a flexible nanoscopic molecule. In agreement with recent experiments, the self-diffusion constant increases with pH, revealing the importance of dielectric friction in the diffusion process. The shape of a dendrimer is found to fluctuate on a nanosecond time scale. We argue that this flexibility (and also the porosity) of the dendrimer may play an important role in determining the mean square displacement of the dendrimer and the breakdown of the Stokes-Einstein relation between diffusion constant and the radius.

  12. New analytical methodology for analysing S(IV) species at low pH solutions by one stage titration method (bichromatometry) with a clear colour change. Could potentially replace the state-of-art-method iodometry at low pH analysis due higher accuracy.

    Science.gov (United States)

    Santasalo-Aarnio, Annukka; Galfi, Istvan; Virtanen, Jorma; Gasik, Michael M

    2017-01-01

    A new, faster and more reliable analytical methodology for S(IV) species analysis at low pH solutions by bichromatometry is proposed. For decades the state of the art methodology has been iodometry that is still well justified method for neutral solutions, thus at low pH media possess various side reactions increasing inaccuracy. In contrast, the new methodology has no side reactions at low pH media, requires only one titration step and provides a clear color change if S(IV) species are present in the solution. The method is validated using model solutions with known concentrations and applied to analyses of gaseous SO2 from purged solution in low pH media samples. The results indicate that bichromatometry can accurately analyze SO2 from liquid samples having pH even below 0 relevant to metallurgical industrial processes.

  13. Influence of storage solution on enamel demineralization submitted to pH cycling Influência da solução de armazenagem na desmineralização do esmalte submetido à ciclagem de pH

    Directory of Open Access Journals (Sweden)

    Juliana Silva Moura

    2004-09-01

    Full Text Available Extracted human teeth are frequently used for research or educational purposes. Therefore, it is necessary to store them in disinfectant solutions that do not alter dental structures. Thus, this study evaluated the influence of storage solution on enamel demineralization. For that purpose, sixty samples were divided into the following groups: enamel stored in formaldehyde (F1, stored in thymol (T1, stored in formaldehyde and submitted to pH cycling (F2, stored in thymol and submitted to pH cycling (T2. All samples were evaluated by cross-sectional microhardness analysis and had their percentage of mineral volume versus micrometer (integrated area determined. Differences between groups were found up to 30-µm depth from the enamel surface (p Dentes humanos extraídos são freqüentemente utilizados para propósitos educacionais ou de pesquisa. Desta forma, é necessário o armazenamento dos mesmos em soluções desinfetantes que não alterem a estrutura dental. Para tanto, sessenta espécimes foram divididos nos seguintes grupos: esmalte armazenado em formol (F1, armazenado em timol (T1, armazenado em formol e submetido à ciclagem de pH (F2 e armazenado em timol e submetido à ciclagem de pH (T2, sendo avaliados por meio de análise de microdureza longitudinal e tiveram a porcentagem de volume mineral pro micrômetro determinada. Diferenças entre os grupos foram encontradas até a profundidade de 30µm da superfície do esmalte (p<0,05, onde o grupo mais desmineralizado era T2. Foi concluído que a solução de armazenagem influenciou na reação do substrato dental a um desafio cariogênico, sugerindo que o formaldeído pode aumentar a resistência do esmalte à desmineralização promovida pelo modelo de ciclagem de pH, quando comparado à desmineralização ocorrida no esmalte armazenado em timol.

  14. Preparing for Graduate-Level Training in Professional Psychology: Comparisons across Clinical PhD, Counseling PhD, and Clinical PsyD Programs

    Science.gov (United States)

    Karazsia, Bryan T.; Smith, Lena

    2016-01-01

    In the present study, faculty who teach in clinical and counseling doctor of philosophy (PhD) or doctor of psychology (PsyD) programs completed surveys regarding preferences for prospective student preparations to graduate programs. Faculty expectations of minimum and ideal undergraduate training were highest for scientific methods, though…

  15. Dry matter and nitrogen accumulation are not affected by superoptimal concentration of ammonium in flowing solution culture with pH control

    Science.gov (United States)

    Rideout, J. W.; Raper, C. D. Jr; Raper CD, J. r. (Principal Investigator)

    1994-01-01

    While it is known that superoptimal concentrations of the nitrate (NO3-) ion in solution culture do not increase NO3- uptake or dry matter accumulation, the same is not known for the ammonium (NH4+) ion. An experiment was conducted utilizing flowing solution culture with pH control to investigate the influence of superoptimal NH4+ concentrations on dry matter, nitrogen (N), potassium (K), calcium (Ca), and magnesium (Mg) accumulation by nonnodulated soybean plants. Increasing the NH4+ concentration in solution from 1 to 10 mM did not affect dry matter or N accumulation. Accumulations of K, Ca, and Mg were slightly decreased with increased NH4+ concentration. The NH4+ uptake system, which is saturated at less than 1mM NH4+, is able to regulate uptake of NH4+ at concentrations as high as 10 mM.

  16. Effect of Strength and Microstructure on Stress Corrosion Cracking Behavior and Mechanism of X80 Pipeline Steel in High pH Carbonate/Bicarbonate Solution

    Science.gov (United States)

    Zhu, Min; Du, Cuiwei; Li, Xiaogang; Liu, Zhiyong; Wang, Shengrong; Zhao, Tianliang; Jia, Jinghuan

    2014-04-01

    The stress corrosion cracking (SCC) behaviors and mechanisms of X80 pipeline steels with different strength and microstructure in high pH carbonate/bicarbonate solution were investigated by slow strain rate testing and electrochemical test. The results showed that the cracking mode of low strength X80 steel composed of bulky polygonal ferrite and granular bainite in high pH solution was intergranular (IGSCC), and the SCC mechanism was anodic dissolution (AD). While the mixed cracking mode of high strength X80 steel consisted of fine acicular ferrite and granular bainite was intergranular (IGSCC) in the early stage, and transgranular (TGSCC) in the later stage. The decrease of pH value of crack tip was probably the key reason for the occurrence of TGSCC. The SCC mechanism may be a mixed mode of AD and hydrogen embrittlement (HE), and the HE mechanism may play a significant role in the deep crack propagation at the later stage. The cracking modes and SCC mechanisms of the two X80 steels were associated with its microstructure and strength.

  17. Self-assembly behavior of pH- and thermosensitive amphiphilic triblock copolymers in solution: experimental studies and self-consistent field theory simulations.

    Science.gov (United States)

    Cai, Chunhua; Zhang, Liangshun; Lin, Jiaping; Wang, Liquan

    2008-10-09

    We investigated, both experimentally and theoretically, the self-assembly behaviors of pH- and thermosensitive poly(L-glutamic acid)- b-poly(propylene oxide)-b-poly(L-glutamic acid) (PLGA-b-PPO-b-PLGA) triblock copolymers in aqueous solution by means of transmission electron microscopy (TEM), scanning electron microscopy (SEM), dynamic light scattering (DLS), circular dichroism (CD), and self-consistent field theory (SCFT) simulations. Vesicles were observed when the hydrophilic PLGA block length is shorter or the pH value of solution is lower. The vesicles were found to transform to spherical micelles when the PLGA block length increases or its conformation changes from helix to coil with increasing the pH value. In addition, increasing temperature gives rise to a decrease in the size of aggregates, which is related to the dehydration of the PPO segments at higher temperatures. The SCFT simulation results show that the vesicles transform to the spherical micelles with increasing the fraction or statistical length of A block in model ABA triblock copolymer, which corresponds to the increase in the PLGA length or its conformation change from helix to coil in experiments, respectively. The SCFT calculations also provide chain distribution information in the aggregates. On the basis of both experimental and SCFT results, the mechanism of the structure change of the PLGA- b-PPO- b-PLGA aggregates was proposed.

  18. Hemoglobin bioconjugates with surface-protected gold nanoparticles in aqueous media: The stability depends on solution pH and protein properties.

    Science.gov (United States)

    Del Caño, Rafael; Mateus, Lucia; Sánchez-Obrero, Guadalupe; Sevilla, José Manuel; Madueño, Rafael; Blázquez, Manuel; Pineda, Teresa

    2017-11-01

    The identification of the factors that dictate the formation and physicochemical properties of protein-nanomaterial bioconjugates are important to understand their behavior in biological systems. The present work deals with the formation and characterization of bioconjugates made of the protein hemoglobin (Hb) and gold nanoparticles (AuNP) capped with three different molecular layers (citrate anions (c), 6-mercaptopurine (MP) and ω-mercaptoundecanoic acid (MUA)). The main focus is on the behavior of the bioconjugates in aqueous buffered solutions in a wide pH range. The stability of the bioconjugates have been studied by UV-visible spectroscopy by following the changes in the localized surface resonance plasmon band (LSRP), Dynamic light scattering (DLS) and zeta-potential pH titrations. It has been found that they are stable in neutral and alkaline solutions and, at pH lower than the protein isoelectric point, aggregation takes place. Although the surface chemical properties of the AuNPs confer different properties in respect to colloidal stability, once the bioconjugates are formed their properties are dictated by the Hb protein corona. The protein secondary structure, as analyzed by Attenuated total reflectance infrared (ATR-IR) spectroscopy, seems to be maintained under the conditions of colloidal stability but some small changes in protein conformation take place when the bioconjugates aggregate. These findings highlight the importance to keep the protein structure upon interaction with nanomaterials to drive the stability of the bioconjugates. Copyright © 2017 Elsevier Inc. All rights reserved.

  19. A highly selective chemosensor for colorimetric detection of Hg2+ and fluorescence detection of pH changes in aqueous solution

    International Nuclear Information System (INIS)

    Kavitha, Ramasamy; Stalin, Thambusamy

    2014-01-01

    A naturally existing and unmodified simple chemosensor, 2-hydroxy-1,4-naphthoquinone (2HNQ), was identified and used for both the colorimetric detection of Hg 2+ and the fluorescent (on-off) detection of pH. The distinct color change and quenching of fluorescence emission was visible to the naked eye. More importantly, the chemosensor was used in combination with β-cyclodextrin (β-CD), which enabled the sensor to be solubilized and stabilized in aqueous solutions. The sensor selectively detected Hg 2+ via the stable 1:1 complexation of the CåO and OH groups with Hg 2+ and reflected pH changes in the range from 6 to 12 via a fluorescence on–off response resulting from the deprotonation of the hydroxyl group in 2HNQ. - Highlights: • The 2-Hydroxy-1,4-Naphthoquinone (2HNQ) chemosensor is capable of both colorimetric detection of Hg 2+ and a fluorescence on-off response to pH. • The distinct color change and quenching of fluorescence emission are detectable with the naked eye. • The on– off fluorescence response in the pH range from 6– to 12 is due to the deprotonation of the hydroxyl group in 2HNQ

  20. Growth rates of three geographically separated strains of the ichthyotoxic Prymnesium parvum (Prymnesiophyceae) in response to six different pH levels

    Science.gov (United States)

    Lysgaard, Maria L.; Eckford-Soper, Lisa; Daugbjerg, Niels

    2018-05-01

    Continued anthropogenic carbon emissions are expected to cause a decline in global average pH of the oceans to a projected value of 7.8 by the end of the century. Understanding how harmful algal bloom (HAB) species will respond to lowered pH levels will be important when predicting future HAB events and their ecological consequences. In this study, we examined how manipulated pH levels affected the growth rate of three strains of Prymnesium parvum from North America, Denmark and Japan. Triplicate strains were grown under pH conditions ranging from 6.6 to 9.1 to simulate plausible future levels. Different tolerances were evident for all strains. Significantly higher growth rates were observed at pH 6.6-8.1 compared to growth rates at pH 8.6-9.1 and a lower pH limit was not observed. The Japanese strain (NIES-1017) had the highest maximum growth rate of 0.39 divisions day-1 at pH 6.6 but a low tolerance (0.22 divisions day-1) to high levels (pH 9.1) with growth declining markedly after pH 7.6. The Danish (SCCAP K-0081) and North American (UTEX LB 2797) strains had maximum growth rates of 0.26 and 0.35 divisions day-1, respectively between pH 6.6-8.1. Compared to the other two strains the Danish strain had a statistically lower growth rate across all pH treatments. Strain differences were either attributed to their provenance or the length of time the strain had been in culture.

  1. Charge-leveling and proper treatment of long-range electrostatics in all-atom molecular dynamics at constant pH.

    Science.gov (United States)

    Wallace, Jason A; Shen, Jana K

    2012-11-14

    Recent development of constant pH molecular dynamics (CpHMD) methods has offered promise for adding pH-stat in molecular dynamics simulations. However, until now the working pH molecular dynamics (pHMD) implementations are dependent in part or whole on implicit-solvent models. Here we show that proper treatment of long-range electrostatics and maintaining charge neutrality of the system are critical for extending the continuous pHMD framework to the all-atom representation. The former is achieved here by adding forces to titration coordinates due to long-range electrostatics based on the generalized reaction field method, while the latter is made possible by a charge-leveling technique that couples proton titration with simultaneous ionization or neutralization of a co-ion in solution. We test the new method using the pH-replica-exchange CpHMD simulations of a series of aliphatic dicarboxylic acids with varying carbon chain length. The average absolute deviation from the experimental pK(a) values is merely 0.18 units. The results show that accounting for the forces due to extended electrostatics removes the large random noise in propagating titration coordinates, while maintaining charge neutrality of the system improves the accuracy in the calculated electrostatic interaction between ionizable sites. Thus, we believe that the way is paved for realizing pH-controlled all-atom molecular dynamics in the near future.

  2. Effect of interactions between carbon dioxide enrichment and NH4+/NO3- ratio on pH of culturing nutrient solution,growth and vigor of tomato root system

    Institute of Scientific and Technical Information of China (English)

    Juan LI; Jianmin ZHOU

    2008-01-01

    A growth chamber experiment was conducted to investigate the influence of NH4+/NO3- ratio and elevated CO2 concentration on the pH in nutrient solution,growth and root vigor system of tomato seedling roots,which attempts to understand whether the elevated CO2 concentration can alleviate the harmful effects of higher NH4+-N concentration in nutrient solutions on the tomato root system.Tomato (Lycopersicon esculenturn Mill.var.Hezuo 906) was grown in pots with nutrient solutions varying in NH4+/NO3- ratio (0:1,1:3,1:1,3:1and 1:0) and the growth chambers were supplied with with the growth process and CO2 concentration increased.At both CO2 levels,pH increased when 100% NO3--N was supplied and decreased in other treatments.The pH decrease in the nutrient solution was directly correlated to the NH4+-N proportion.The pH value was more reduced in 100% NH4+-N nutrient solution than increased in the 100% NO3--N nutrient solution.CO2 enrichment increased the dry weight of shoots and roots,root vigor system,total absorbing area and active absorbing area of tomato seedlings.All the measurement indexes above were increased in the elevated CO2 concentration treatment with the NO3- proportion increase in the nutrient solutions.Thus,under the elevated CO2 concentration,the dry weights of shoots and roots,root vigor system,total root absorbing area and active absorbing area were found to be inversely correlated to NH4+/NO3- ratio,leading to about 65.8%,78.0%,18.9%,12.9% and 18.9% increase,respectively,compared with that under the ambient CO2 concentration.Our results indicated that tomato seedling roots may benefit mostly from CO2 enrichment when 100% NO3--N nutrient solutions was supplied,but the CO2 concentration elevation did not alleviate the harmful effects when 100% NHa+-N was supplied.

  3. Effect of dietary roughage level on chewing activity, ruminal pH, and saliva secretion in lactating Holstein cows.

    Science.gov (United States)

    Jiang, F G; Lin, X Y; Yan, Z G; Hu, Z Y; Liu, G M; Sun, Y D; Liu, X W; Wang, Z H

    2017-04-01

    Increasing dietary roughage level is a commonly used strategy to prevent subacute ruminal acidosis. We hypothesized that high-roughage diets could promote chewing activity, saliva secretion, and hence more alkaline to buffer rumen pH. To verify the hypothesis, 12 multiparous Holstein cows in mid lactation were randomly allocated to 4 treatments in a triplicated 4 × 4 Latin square experiment with one cow in each treatment surgically fitted with a ruminal cannula. Treatments were diets containing 40, 50, 60, or 70% of roughage on a DM basis. Increasing dietary roughage level decreased DM, CP, OM, starch, and NE L intake, increased ADF intake, and decreased milk yield linearly. Intake of NDF was quite stable across treatments and ranged from 7.8 to 8.1 kg/d per cow. Daily eating time increased linearly with increased roughage level. The increase in eating time was due to increased eating time per meal but not number of meals per day, which was stable and ranged from 8.3 to 8.5 meals per day across treatments. Increasing dietary roughage level had no effect on ruminating time (min/d), the number of ruminating periods (rumination periods per d), and chewing time per ruminating period (min/ruminating period). Ruminating time per kilogram of NDF intake and total chewing time per kilogram of ADF intake were similar across treatments (57.4 and 183.8 min/kg, respectively). Increasing dietary roughage level linearly increased daily total chewing time; linearly elevated the mean, maximum, and minimum ruminal pH; and linearly decreased total VFA concentration and molar proportion of propionate in ruminal fluid. Saliva secretion during eating was increased, the secretion during rumination was unaffected, but the secretion during resting tended to decrease with increased dietary roughage level. As a result, total saliva secretion was not affected by treatments. In conclusion, the results of the present study did not support the concept that high-roughage diets elevated ruminal pH

  4. Corrosion Effects on the Fatigue Crack Propagation of Giga-Grade Steel and its Heat Affected Zone in pH Buffer Solutions for Automotive Application

    Science.gov (United States)

    Lee, H. S.

    2018-03-01

    Corrosion fatigue crack propagation test was conducted of giga-grade steel and its heat affected zone in pH buffer solutions, and the results were compared with model predictions. Pure corrosion effect on fatigue crack propagation, particularly, in corrosive environment was evaluated by means of the modified Forman equation. As shown in results, the average corrosion rate determined from the ratio of pure corrosion induced crack length to entire crack length under a cycle load were 0.11 and 0.37 for base metal and heat affected zone, respectively, with load ratio of 0.5, frequency of 0.5 and pH 10.0 environment. These results demonstrate new interpretation methodology for corrosion fatigue crack propagation enabling the pure corrosion effects on the behavior to be determined.

  5. Degradation kinetics of fisetin and quercetin in solutions affected by medium pH, temperature and co-existed proteins

    Directory of Open Access Journals (Sweden)

    Wang Jing

    2016-01-01

    Full Text Available Impacts of medium pH, temperature and coexisted proteins on the degradation of two flavonoids fisetin and quercetin were assessed by spectroscopic method in the present study. Based on the measured degradation rate constants (k, fisetin was more stable than quercetin in all cases. Increasing medium pH from 6.0 to 7.5 at 37°C enhanced respective k values of fisetin and quercetin from 8.30x10−3 and 2.81x10−2 to 0.202 and 0.375 h-1 (P<0.05. In comparison with their degradation at 37°C, fisetin and quercetin showed larger k values at higher temperature (0.124 and 0.245 h−1 at 50°C, or 0.490 and 1.42 h−1 at 65°C. Four protein products in medium could stabilize the two flavonoids (P<0.05, as these proteins at 0.10 g L-1 decreased respective k values of fisetin and quercetin to 2.28x10−2-2.98x10−2 and 4.37´10−2-5.97x10−2 h−1. Hydrophobic interaction between the proteins and the two flavonoids was evidenced responsible for the stabilization, as sodium dodecyl sulfate could destroy the stabilization significantly (P<0.05. Casein and soybean protein provided greater stabilization than whey protein isolate. It is thus concluded that higher temperature and alkaline pH can enhance flavonoid loss, whereas coexisted proteins as flavonoid stabilizers can inhibit flavonoid degradation.

  6. Passive behaviour of alloy corrosion-resistant steel Cr10Mo1 in simulating concrete pore solutions with different pH

    International Nuclear Information System (INIS)

    Ai, Zhiyong; Jiang, Jinyang; Sun, Wei; Song, Dan; Ma, Han; Zhang, Jianchun; Wang, Danqian

    2016-01-01

    Highlights: • A new alloy corrosion-resistant steel Cr10Mo1 is developed for reinforcing rebar of concrete in severe environments. • The effects of pH on the passive behaviour of Cr10Mo1 steel compared with plain carbon steel were studied systematically by electrochemical techniques and surface analysis. • The mechanism for self-reinforcing passivity against carbonation of the corrosion-resistant steel is revealed. - Abstract: The passive behaviour of new alloy corrosion-resistant steel Cr10Mo1 and plain carbon steel (as a comparison) in simulating concrete pore solutions of different pH (ranging from 13.5 to 9.0) under open circuit potential conditions, was evaluated by various electrochemical techniques: potentiodynamic polarization, capacitance measurements and electrochemical impedance spectroscopy. The chemical composition and structure of passive films were investigated by X-ray photoelectron spectroscopy (XPS) and secondary ion mass spectroscopy (SIMS). The electrochemical responses of passive films show that Cr10Mo1 steel has an increasing passivity with pH decreasing while carbon steel dose conversely, revealing carbonation does no negative effect on passivation of the corrosion-resistant steel. SIMS reveals that the passive film on the corrosion-resistant steel presents a bilayer structure: an outer layer mainly consisting of Fe oxides and hydroxides, and an inner layer enriched in Cr species, while only a Fe-concentrated layer for carbon steel. According to the XPS analysis results, as the pH decreases, more stable and protective Cr oxides are enriched in the film on Cr10Mo1 steel while Fe oxides gradually decompose. Higher content of Cr oxides in the film layer provides Cr10Mo1 corrosion-resistant steel more excellent passivity at lower pH.

  7. Passive behaviour of alloy corrosion-resistant steel Cr10Mo1 in simulating concrete pore solutions with different pH

    Energy Technology Data Exchange (ETDEWEB)

    Ai, Zhiyong, E-mail: 230139452@seu.edu.cn [School of Materials Science and Engineering, Southeast University, Nanjing 211189, Jiangsu (China); Jiangsu Key Laboratory of Construction Materials, Nanjing 211189, Jiangsu (China); Jiang, Jinyang, E-mail: jiangjinyang16@163.com [School of Materials Science and Engineering, Southeast University, Nanjing 211189, Jiangsu (China); Jiangsu Key Laboratory of Construction Materials, Nanjing 211189, Jiangsu (China); Sun, Wei, E-mail: sunwei@seu.edu.cn [School of Materials Science and Engineering, Southeast University, Nanjing 211189, Jiangsu (China); Jiangsu Key Laboratory of Construction Materials, Nanjing 211189, Jiangsu (China); Song, Dan, E-mail: songdancharls@hhu.edu.cn [School of Materials Science and Engineering, Southeast University, Nanjing 211189, Jiangsu (China); Jiangsu Key Laboratory of Construction Materials, Nanjing 211189, Jiangsu (China); College of Mechanics and Materials, Hohai University, Nanjing 210098, Jiangsu (China); Ma, Han, E-mail: mahan-iris@shasteel.cn [Research Institute of Jiangsu Shasteel Iron and Steel, Zhangjiagang 215625, Jiangsu (China); Zhang, Jianchun, E-mail: Zhangjc-iris@shasteel.cn [Research Institute of Jiangsu Shasteel Iron and Steel, Zhangjiagang 215625, Jiangsu (China); Wang, Danqian, E-mail: wonderbaba@126.com [School of Materials Science and Engineering, Southeast University, Nanjing 211189, Jiangsu (China); Jiangsu Key Laboratory of Construction Materials, Nanjing 211189, Jiangsu (China)

    2016-12-15

    Highlights: • A new alloy corrosion-resistant steel Cr10Mo1 is developed for reinforcing rebar of concrete in severe environments. • The effects of pH on the passive behaviour of Cr10Mo1 steel compared with plain carbon steel were studied systematically by electrochemical techniques and surface analysis. • The mechanism for self-reinforcing passivity against carbonation of the corrosion-resistant steel is revealed. - Abstract: The passive behaviour of new alloy corrosion-resistant steel Cr10Mo1 and plain carbon steel (as a comparison) in simulating concrete pore solutions of different pH (ranging from 13.5 to 9.0) under open circuit potential conditions, was evaluated by various electrochemical techniques: potentiodynamic polarization, capacitance measurements and electrochemical impedance spectroscopy. The chemical composition and structure of passive films were investigated by X-ray photoelectron spectroscopy (XPS) and secondary ion mass spectroscopy (SIMS). The electrochemical responses of passive films show that Cr10Mo1 steel has an increasing passivity with pH decreasing while carbon steel dose conversely, revealing carbonation does no negative effect on passivation of the corrosion-resistant steel. SIMS reveals that the passive film on the corrosion-resistant steel presents a bilayer structure: an outer layer mainly consisting of Fe oxides and hydroxides, and an inner layer enriched in Cr species, while only a Fe-concentrated layer for carbon steel. According to the XPS analysis results, as the pH decreases, more stable and protective Cr oxides are enriched in the film on Cr10Mo1 steel while Fe oxides gradually decompose. Higher content of Cr oxides in the film layer provides Cr10Mo1 corrosion-resistant steel more excellent passivity at lower pH.

  8. A cow-level association of ruminal pH on body condition score, serum beta-hydroxybutyrate and postpartum disorders in Thai dairy cattle

    NARCIS (Netherlands)

    Inchaisri, C.; Chanpongsang, S.; Noordhuizen, J.; Hogeveen, H.

    2014-01-01

    Subacute ruminal acidosis in dairy cows occurs when ruminal pH is below about 5.5. However, the exact threshold level of ruminal pH affecting cow health is still in debate. This investigation was carried out in 505 cows within 31 farms. The postpartum disorders, including dystocia, retained

  9. Influence on Levels of Information as Presented by Different Technologies on Students' Understanding of Acid, Base, and pH Concepts.

    Science.gov (United States)

    Nakhleh, Mary B.; Krajcik, Joseph S.

    1994-01-01

    Involves secondary students in a study designed to allow investigation into how different levels of information presented by various technologies (chemical indicators, pH meters, and microcomputer-based laboratories-MBLs) affected students' understanding of acid, base, and pH concepts. Results showed that students using MBLs exhibited a greater…

  10. Changes in soil solution Zn and pH and uptake of Zn by arbuscular mycorrhizal red clover in Zn-contaminated soil.

    Science.gov (United States)

    Li, X; Christie, P

    2001-01-01

    Red clover plants inoculated with Glomus mosseae were grown in a sterile pasture soil containing 50 mg Zn kg(-1) in 'Plexiglas' (acrylic) containers with nylon net partitions (30 microm mesh) designed to separate the soil into a central root zone and two outer zones for hyphal growth with no root penetration. Two porous plastic soil moisture samplers were installed in each pot, one in the root compartment and the other in one of the hyphal compartments. The soil in the outer compartments was amended with one of the four application rates of Zn (as ZnSO4) ranging from 0 to 1000 mg kg(-1). Non-mycorrhizal controls were included, and there were five replicates of each treatment in a randomised block in a glasshouse. Uninoculated plants received supplementary P to avoid yield limitation due to low soil P status. Plants grew in the central compartment for nine weeks. Soil moisture samples were collected 4, 24 and 62 days after sowing to monitor changes in the Zn concentration and pH of the soil solution. At harvest, the mean mycorrhizal infection rate of inoculated plants ranged from 29% to 34% of total root length and was little affected by Zn application. Root and shoot yields were not affected by mycorrhizal infection. Plant Zn concentration and uptake were lower in mycorrhizal plants than non-mycorrhizal controls, and this effect was more pronounced with increasing Zn application rate to the soil. Soil solution Zn concentrations were lower and pH values were higher in mycorrhizal treatments than non-mycorrhizal controls and the mycorrhiza effect was more pronounced at higher Zn application rates. The protective effect of mycorrhiza against plant Zn uptake may have been associated with changes in Zn solubility mediated by changes in the soil solution pH, or by immobilisation of Zn in the extraradical mycelium.

  11. A cow-level association of ruminal pH on body condition score, serum beta-hydroxybutyrate and postpartum disorders in Thai dairy cattle.

    Science.gov (United States)

    Chaidate, Inchaisri; Somchai, Chanpongsang; Jos, Noordhuizen; Henk, Hogeveen

    2014-09-01

    Subacute ruminal acidosis in dairy cows occurs when ruminal pH is below about 5.5. However, the exact threshold level of ruminal pH affecting cow health is still in debate. This investigation was carried out in 505 cows within 31 farms. The postpartum disorders, including dystocia, retained placenta, anestrus, cystic ovary, metritis, clinical mastitis and lameness, were analyzed. Ruminal pH, serum beta-hydroxy butyrate (SBHB), serum urea nitrogen and body condition score (BCS) were measured once during the 3 to 6 weeks postpartum, while BCS was determined once more at 1 week before calving. Ruminal pH was determined by ruminocentesis technique. The ruminal pH was evaluated to study the association with BCS, SBHB and postpartum disorders using linear regression in a generalized linear mixed model with farm as a random effect. The results show that low ruminal pH was associated with dystocia, metritis and lameness. Moreover, a low ruminal pH can be found in cows with a high loss of BCS after calving and also in cows with low SBHB postpartum. These findings confirmed the feasibility of the ruminocentesis technique and the association of low ruminal pH on various postpartum disorders at the individual cow level. However, the consequences of low ruminal pH on dairy cow health still needs more exploration for a better understanding of the physiological mechanisms. © 2014 Japanese Society of Animal Science.

  12. Reflection-mode micro-spherical fiber-optic probes for in vitro real-time and single-cell level pH sensing.

    Science.gov (United States)

    Yang, Qingbo; Wang, Hanzheng; Lan, Xinwei; Cheng, Baokai; Chen, Sisi; Shi, Honglan; Xiao, Hai; Ma, Yinfa

    2015-02-01

    pH sensing at the single-cell level without negatively affecting living cells is very important but still a remaining issue in the biomedical studies. A 70 μm reflection-mode fiber-optic micro-pH sensor was designed and fabricated by dip-coating thin layer of organically modified aerogel onto a tapered spherical probe head. A pH sensitive fluorescent dye 2', 7'-Bis (2-carbonylethyl)-5(6)-carboxyfluorescein (BCECF) was employed and covalently bonded within the aerogel networks. By tuning the alkoxide mixing ratio and adjusting hexamethyldisilazane (HMDS) priming procedure, the sensor can be optimized to have high stability and pH sensing ability. The in vitro real-time sensing capability was then demonstrated in a simple spectroscopic way, and showed linear measurement responses with a pH resolution up to an average of 0.049 pH unit within a narrow, but biological meaningful pH range of 6.12-7.81. Its novel characterizations of high spatial resolution, reflection mode operation, fast response and high stability, great linear response within biological meaningful pH range and high pH resolutions, make this novel pH probe a very cost-effective tool for chemical/biological sensing, especially within the single cell level research field.

  13. [Effect of amino acid solutions on the blood ammonia level].

    Science.gov (United States)

    Sanjo, K; Harihara, Y; Kawasaki, S; Umekita, N; Idezuki, Y

    1985-09-01

    We have carried out several basic experiments on artificial liver support and found that the plasma free amino acid balance was lost after treatment according to this procedure. Application of fluid therapy--Using conventional amino acid preparations available on the market--Is not adequate during and after the treatment with artificial liver. Fluid therapy using mainly special amino acid preparations should have been established; preparations, named Todai Hospital fluid (THF), are intended to correct the deranged aminogram, supply nutrition and promote the improvement in symptoms. Furthermore, experimental animals with acute hepatic insufficiency of diverse severity were prepared and basic experiments were performed which these animals to see how the efficacy of THF developed. In the basic experiments, psychoneurotic symptoms and the electroencephalogram were improved with the lowering of the blood ammonia level. Clinically, THF was not only used as a therapeutic agent after treatment by artificial liver support in patients with fulminant hepatitis, but is also served as a further indication in hepatic encephalopathy accompanying chronic liver diseases in late stages. Improvement in encephalopathy was observed immediately after the administration of THF and persisted while the aminogram pattern returned to the premedication representation. There was more improvement in patients in whom ammonemia was complicated, and the blood ammonia level was reduced markedly.

  14. Effects of pH and Competing Anions on the Solution Speciation of Arsenic by Ion Exchange Resins

    Energy Technology Data Exchange (ETDEWEB)

    Impellitteri, Christopher A.; Ryan, JAmes A.; Al-Abed, Souhail R.; Scheckel, Kirk G.; Randall, Paul M.; Richardson, Collin A.

    2003-03-26

    Anion-exchange resins (AER) are used to differentiate As(V) and As(III) by retaining As(V) and allowing As(III) to pass through. AERs allow rapid speciation of As in the field which precludes the effects of sample preservation on As speciation. Aqueous environmental samples contain anions that may interfere with the speciation of As. This study compares the speciation of As by two commercially available AERs. A silica-based AER was selected for further study. As(V) and As(III) were passed through the AER in the presence of NO3 -, SO4 2-, HPO4 2-, Cl- and HCO3 - at pH 4, 6 and 8. Recoveries of As species in mixed systems range between 90 to 100%. Breakthrough curves for As(V) are presented which allow calculation of loading rates. HPO4 2- has the greatest effect on the speciation of As by AER.

  15. Low-level waste management - suggested solutions for problem wastes

    International Nuclear Information System (INIS)

    Pechin, W.H.; Armstrong, K.M.; Colombo, P.

    1984-01-01

    Problem wastes are those wastes which are difficult or require unusual expense to place into a waste form acceptable under the requirements of 10 CFR 61 or the disposal site operators. Brookhaven National Laboratory has been investigating the use of various solidification agents as part of the DOE Low-Level Waste Management Program for several years. Two of the leading problem wastes are ion exchange resins and organic liquids. Ion exchange resins can be solidified in Portland cement up to about 25 wt % resin, but waste forms loaded to this degree exhibit significantly reduced compressive strength and may disintegrate when immersed in water. Ion exchange resins can also be incorporated into organic agents. Mound Laboratory has been investigating the use of a joule-heated glass melter as a means of disposing of ion exchange resins and organic liquids in addition to other combustible wastes

  16. Chemical hazards from decontamination solutions in low level waste

    International Nuclear Information System (INIS)

    Leventhal, L.; Miller, A.; Turney, J.; Naughton, M.; IMPELL Corp., Walnut Creek, CA; Electric Power Research Inst., Palo Alto, CA)

    1985-01-01

    Recent regulations are focussing more attention on the non-radioactive matrix materials associated with radioactive wastes. Decontamination of operating facilities is becoming a more significant source of low-level waste. This study reviewed the chemical and biological hazards of over 50 decontamination processes. Seventeen of the most prominent hard and soft decontamination processes were examined in detail. The chemical and biological hazards of these seventeen are presented in this paper. These hazards influence the choice of radwaste processing and packaging operations and methods. Federal, state and local regulations further impact on operations and waste disposal. Hazards to personnel, in plant and off-site, resulting from the decontamination cycle are evaluated. 1 fig., 5 tabs

  17. Study of the pitting and repassiv,tion corrosion potential of zicaloy-4 halides solutions at 250C and several pH

    International Nuclear Information System (INIS)

    Gardiazabal, J.I.; Cordova, R.; Gomez, H.; Layana, G.; Schrebler, R.

    1987-01-01

    The electrochemical behaviour of Zircaloy-4 electrode in chloride, bromide and iodide acid solution was investigated at 25 0 C employing stationary, quasi-stationary and potentiodynamic techniques. The results show that the pitting and repassivation potentials are independent on pH but both are dependent on halice concentration, following linear relation ships in these cases. It is also possible to correlate the pitting potential with the ionic radius of the anions, allowing thus to establish an order in their agressive properties. This order was extrapolated for fluoride ion and further experimental measurements show that the corrosion potential of Zircaloy-4 in acid or neutra solution of this ion (which undergoes active dissolution) is coincident with that predicted from the Ep v/s ionic radius determined for the other halides. (Author) [pt

  18. Effect of pH and uranium concentration on interaction of uranium(VI) and uranium(IV) with organic ligands in aqueous solutions

    International Nuclear Information System (INIS)

    Li, W.C.; Victor, D.M.; Chakrabarti, C.L.

    1980-01-01

    The effect of pH and uranium concentration on the interactions of uranium(VI) and uranium(IV) with organic ligands was studied by employing dialysis and ultrafiltration techniques. The interactions of U(VI) and U(IV) with organic ligands in nitrate or chloride aqueous solution have been found to be pH-dependent. The stability constants of uranium-organic complexes decrease in the order: fulvic acid>humic acid>tannic acid for U(VI) and humic acid>tannic acid>fulvic acid for U(IV). Scatchard plots for the uranium-organic acid systems indicate two types of binding sites with a difference in stability constants of about 10 2 . Ultrafiltration of uranium-humic acid complexes indicates that U(VI) and U(IV) ions are concentrated in larger molecular size fractions (>5.1 nm) at pH less than or equal to 3 and in smaller molecular size fractions (in the range 5.1 to 3.1 nm and 2.4 to 1.9 nm) at pH greater than or equal to 5. 7 figures, 4 tables

  19. Electrochemical characteristics of bioresorbable binary MgCa alloys in Ringer's solution: Revealing the impact of local pH distributions during in-vitro dissolution.

    Science.gov (United States)

    Mareci, D; Bolat, G; Izquierdo, J; Crimu, C; Munteanu, C; Antoniac, I; Souto, R M

    2016-03-01

    Biodegradable magnesium-calcium (MgCa) alloy is a very attractive biomaterial. Two MgCa alloys below the solid solubility of Ca were considered, as to solely investigate the effect of Ca content on the behavior of magnesium and the pH changes associated to metal dissolution. X-ray diffraction analysis and optical microscopy showed that both Mg-0.63Ca and Mg-0.89Ca alloys were solely composed of α(Mg) phase. Degradation characteristics and electrochemical characterization of MgCa alloys were investigated during exposure to Ringer's solution at 37 °C by electrochemical impedance spectroscopy and scanning electrochemical microscopy. The impedance behavior showed both capacitive and inductive features that are related to the alloy charge transfer reaction and the relaxation of the absorbed corrosion compounds, and can be described in terms of an equivalent circuit. Scanning electron microscopy (SEM) was employed to view the surface morphology of the MgCa samples after 1 week immersion in Ringer's solution showing extensive precipitation of corrosion products, whereas the substrate shows evidence of a non-uniform corrosion process. Energy dispersive analysis showed that the precipitates contained oxygen, calcium, magnesium and chlorine, and the Mg:Ca ratios were smaller than in the alloys. Scanning electrochemical microscopy (SECM) was used to visualize local pH changes associated to these physicochemical processes with high spatial resolution. The occurrence of pH variations in excess of 3 units between anodic and cathodic half-cell reactions was monitored in situ. Copyright © 2015 Elsevier B.V. All rights reserved.

  20. The effect of solution pH on the electrochemical performance of nanocrystalline metal ferrites MFe2O4 (M=Cu, Zn, and Ni) thin films

    Science.gov (United States)

    Elsayed, E. M.; Rashad, M. M.; Khalil, H. F. Y.; Ibrahim, I. A.; Hussein, M. R.; El-Sabbah, M. M. B.

    2016-04-01

    Nanocrystalline metal ferrite MFe2O4 (M=Cu, Zn, and Ni) thin films have been synthesized via electrodeposition-anodization process. Electrodeposited (M)Fe2 alloys were obtained from aqueous sulfate bath. The formed alloys were electrochemically oxidized (anodized) in aqueous (1 M KOH) solution, at room temperature, to the corresponding hydroxides. The parameters controlling the current efficiency of the electrodeposition of (M)Fe2 alloys such as the bath composition and the current density were studied and optimized. The anodized (M)Fe2 alloy films were annealed in air at 400 °C for 2 h. The results revealed the formation of three ferrite thin films were formed. The crystallite sizes of the produced films were in the range between 45 and 60 nm. The microstructure of the formed film was ferrite type dependent. The corrosion behavior of ferrite thin films in different pH solutions was investigated using open circuit potential (OCP) and potentiodynamic polarization measurements. The open circuit potential indicates that the initial potential E im of ZnFe2O4 thin films remained constant for a short time, then sharply increased in the less negative direction in acidic and alkaline medium compared with Ni and Cu ferrite films. The values of the corrosion current density I corr were higher for the ZnFe2O4 films at pH values of 1 and 12 compared with that of NiFe2O4 and CuFe2O4 which were higher only at pH value 1. The corrosion rate was very low for the three ferrite films when immersion in the neutral medium. The surface morphology recommended that Ni and Cu ferrite films were safely used in neutral and alkaline medium, whereas Zn ferrite film was only used in neutral atmospheres.

  1. The effect of high pH alkaline solutions on the mineral stability of the Boom Clay - Batch experiments at 60 deg. C

    International Nuclear Information System (INIS)

    Honty, M.; De Craen, M.; Wang, L.; Madejova, J.; Czimerova, A.; Pentrak, M.; Stricek, I.; Van Geet, M.

    2010-01-01

    Boom Clay is currently viewed as a reference host formation for studies on deep geological disposal of radioactive waste in Belgium. The interactions between bulk rock Boom Clay and 0.1 M KOH, 0.1 M NaOH, 0.1 M Ca(OH) 2 , young cement water and evolved cement water solutions, ranging in pH from 12.5 to 13.2, were examined as static batch experiments at 60 deg. C to simulate alkaline plume perturbations, which are expected to occur in the repository due to the presence of concrete. Both liquids and solids were investigated at specific times between 90 and 510 days in order to control the elemental budget and to search for potential mineralogical alterations. Also, the clay fraction was separated from the whole-rock Boom Clay at the end of each run and characterized for its mineralogical composition. Thereby, the importance of the mineral matrix to buffer the alkaline attack and the role of organic matter to protect clay minerals were also addressed. The results indicate that the degree of geochemical perturbation in Boom Clay is dependent on the initial pH of the applied solution together with the nature of the major cation in the reactant fluids. The higher the initial pH of the media, the stronger its interaction with Boom Clay. No major non-clay mineralogical alteration of the Boom Clay was detected, but dissolution of kaolinite, smectite and illite occurred within the studied experimental conditions. The dissolution of clays is accompanied by the decrease in the layer charge, followed by a decrease in the cation-exchange capacity. The highest TOC values coincide with the highest total elemental concentrations in the leachates, and correspondingly, the highest dissolution degree. However, no quantitative link could be established between the degree of organic matter decomposition and clay dissolution.

  2. The nature of rusts and corrosion characteristics of low alloy and plain carbon steels in three kinds of concrete pore solution with salinity and different pH

    International Nuclear Information System (INIS)

    Singh, J.K.; Singh, D.D.N.

    2012-01-01

    Highlights: ► LAS rebars corrode 2–3 times slower than PCS in concrete pore solution and mortars. ► Raman and XRD studies show that goethite and maghemite phases of rusts formed on LAS. ► On PCS unstable phases of lepidocrocite and akaganite are formed. ► EIS confirms more stable rust on LAS than on PCS. ► A model is proposed to explain formation of passive film on surface of steels. - Abstract: Correlation of corrosion characteristics and nature of rusts on low alloy (LA) and plain carbon (PC) steels exposed in simulated concrete pore solution of different pH is studied. Rusts formed under wet/dry conditions are examined by Raman spectroscopy and X-ray diffraction. LA rust is more adherent compared to PC as confirmed by measurement of weight in gain and electrochemical studies. EIS results show improvement in protective properties of steels with passage of time. Both steels are found prone to pitting attack in chloride contaminated pore solution. Rebars embedded in concrete exhibit same trend as recorded in solution exposure tests.

  3. The effect of sulfide on the aerobic corrosion of carbon steel in near-neutral pH saline solutions

    International Nuclear Information System (INIS)

    Sherar, B.W.A.; Keech, P.G.; Shoesmith, D.W.

    2013-01-01

    Highlights: ► The corrosion rate is low when steel is exposed to anaerobic conditions (pH = 8.9). ► An anaerobic to aerobic corrosion with sulfide switch increases the corrosion rate. ► Aerobic exposure induces the formation of goethite-covered tubercles. ► Continual sulfide exposure leads to the slow conversion of goethite to mackinawite. - Abstract: Severe corrosion damage may occur when gas transmission pipelines are exposed, at disbonded coating locations, to trapped waters containing sulfide followed by secondary exposure to air. Aerobic corrosion with sulfide was investigated in a long-term corrosion experiment in which corrosion was monitored by measurement of the corrosion potential and polarization resistance obtained from linear polarization resistance measurements. The properties and composition of the corrosion product deposits formed were determined using scanning electron microscopy, energy dispersive X-ray analysis, and Raman spectroscopy. A switch from aerobic to aerobic-with-sulfide corrosion doubles the relative corrosion rate.

  4. Metabolism of the intervertebral disc: effects of low levels of oxygen, glucose, and pH on rates of energy metabolism of bovine nucleus pulposus cells.

    Science.gov (United States)

    Bibby, Susan R S; Jones, Deborah A; Ripley, Ruth M; Urban, Jill P G

    2005-03-01

    In vitro measurements of metabolic rates of isolated bovine nucleus pulposus cells at varying levels of oxygen, glucose, and pH. To obtain quantitative information on the interactions between oxygen and glucose concentrations and pH, and the rates of oxygen and glucose consumption and lactic acid production, for disc nucleus cells. Disc cells depend on diffusion from blood vessels at the disc margins for supply of nutrients. Loss of supply is thought to lead to disc degeneration, but how loss of supply affects nutrient concentrations in the disc is not known; nutrient concentrations within discs can normally only be calculated, because concentration measurements are invasive. However, realistic predictions cannot be made until there are data from measurements of metabolic rates at conditions found in the disc in vivo, i.e., at low levels of oxygen, glucose, and pH. A metabolism chamber was designed to allow simultaneous recording of oxygen and glucose concentrations and of pH. These concentrations were measured electrochemically with custom-built glucose and oxygen sensors; lactic acid was measured biochemically. Bovine nucleus pulposus cells were isolated and inserted into the chamber, and simultaneous rates of oxygen and glucose consumption and of lactic acid production were measured over a range of glucose, oxygen, and pH levels. There were strong interactions between rates of metabolism and oxygen consumption and pH. At atmospheric oxygen levels, oxygen consumption rate at pH 6.2 was 32% of that at pH 7.4. The rate fell by 60% as oxygen concentration was decreased from 21 to 5% at pH 7.4, but only by 20% at pH 6.2. Similar interactions were seen for lactic acid production and glucose consumption rates; we found that glycolysis rates fell at low oxygen and glucose concentrations and low pH. Equations were derived that satisfactorily predict the effect of nutrient and metabolite concentrations on rates of lactic acid production rate and oxygen consumption. Disc

  5. Effect of X-ray irradiation on germination of rice and wheat at different temperatures and pH levels of water

    International Nuclear Information System (INIS)

    Rajput, T.B.S.; Singh, Jaswant

    1981-01-01

    An experiment was conducted on the germination of ''Jaya'' rice (Oryza sativa Linn.) and ''Sonalika'' wheat (Triticum aestivum Linn. emend. Thell.) to study the effects of low doses of X-ray irradiation at different temperatures and pH levels of water. The percentage of germination was more at pH 7, and decreased with an increase or decrease in pH level. In most of the cases irradiation delayed the germination and proved to be harmful. But at 20deg C, 4 KR X-ray irradiation promoted the germination of rice by more than 15% at pH levels of 5.5-8.5. But in wheat no significant increase in germination percentage was noted at any combination of the parameters. (auth.)

  6. Effect of electrolyte valency, alginate concentration and pH on engineered TiO₂ nanoparticle stability in aqueous solution.

    Science.gov (United States)

    Loosli, Frédéric; Le Coustumer, Philippe; Stoll, Serge

    2015-12-01

    Agglomeration and disagglomeration processes are expected to play a key role on the fate of engineered nanoparticles in natural aquatic systems. These processes are investigated here in detail by studying first the stability of TiO2 nanoparticles in the presence of monovalent and divalent electrolytes at different pHs (below and above the point of zero charge of TiO2) and discussing the importance of specific divalent cation adsorption with the help of the DLVO theory as well as the importance of the nature of the counterions. Then the impact of one polysaccharide (alginate) on the stability of agglomerates formed under pH and water hardness representative of Lake Geneva environmental conditions is investigated. In these conditions the large TiO2 agglomerates (diameter>1μm) are positively charged due to Ca(2+) and Mg(2+) specific adsorption and alginate, which is negatively charged, adsorbs onto the agglomerate surface. Our results indicate that the presence of alginate at typical natural organic matter concentration (1-10 mg L(-1)) strongly modifies the TiO2 agglomerate (50 mg L(-1)) stability by inducing their partial and rapid disagglomeration. The importance of disagglomeration is found dependent on the alginate concentration with maximum of disagglomeration obtained for alginate concentration ≥8 mg L(-1) and leading to 400 nm fragments. From an environmental point of view partial restabilization of TiO2 agglomerates in the presence of alginate constitutes an important outcome. Disagglomeration will enhance their transport and residence time in aquatic systems which is an important step in the current knowledge on risk assessment associated to engineered nanoparticles. Copyright © 2015 Elsevier B.V. All rights reserved.

  7. Spore germination of Gleichenella pectinata (Willd. Ching (Polypodiopsida-Gleicheniaceae at different temperatures, levels of light and pH

    Directory of Open Access Journals (Sweden)

    Eunice Pereira Gonçalves dos Santos

    2010-12-01

    Full Text Available This study investigated the effects of different temperatures (25 and 30 ± 2 ºC, light levels (62, 42, 22 and 5% of natural light, and pH (4.0, 4.5, 5.0, 5.5, 6.0 and 6.7 on the spore germination of Gleichenella pectinata. To accomplish this, the spores were surface sterilized and sown in bottles containing mineral medium. The spores of G. pectinata are monolets and the perispore surface can show large and irregular deposits. During germination, filamentous gametophytes with and without developing rhizoids were observed. Only gametophytes which presented developed rhizoids were able to reach the heart-shaped developmental stage. Based on the collection, the rate of and gametophyte development were generally very low. The relative germination rates were higher at 25 ºC than at 30 °C. Moreover, the highest percentages of gametophytes with developed rhizoids were observed at 22 and 5% of natural light (8.8 ± 2.3% and 11.3 ± 2.2% respectively and the highest percentage of heart-shaped gametophytes were observed at pH 4.5 and 5.0 (1.2 ± 0.8% and 2.2 ± 0.8%, respectively.A finalidade deste estudo foi analisar o potencial germinativo dos esporos de G. pectinata e verificar os efeitos de níveis de luz (62, 42, 22 e 5% da luz natural, das temperaturas de 25 e 30 ºC e de pHs entre 4,0 e 6,7 na germinação. Esporos de G. pectinata são monoletes e a superfície apresenta depósitos grandes e irregulares. Observamos três classes de desenvolvimento: esporos contendo cloroplastos, gametófitos filamentosos sem rizóides desenvolvidos e gametófitos filamentosos com rizóides desenvolvidos. Somente os gametófitos com rizóides desenvolvidos foram capazes de alcançar a fase cordiforme. As porcentagens de germinação foram mais elevadas à temperatura de 25ºC do que 30 ºC. As mais elevadas porcentagens de gametófitos com rizóides desenvolvidos foram observadas sob 22 e 5% da luz natural e as porcentagens mais elevadas de gamet

  8. Modulation of phosducin-like protein 3 (PhLP3 levels promotes cytoskeletal remodelling in a MAPK and RhoA-dependent manner.

    Directory of Open Access Journals (Sweden)

    Nandini V L Hayes

    Full Text Available Phosducin-like protein 3 (PhLP3 forms a ternary complex with the ATP-dependent molecular chaperone CCT and its folding client tubulin. In vitro studies suggest PhLP3 plays an inhibitory role in β-tubulin folding while conversely in vivo genetic studies suggest PhLP3 is required for the correct folding of β-tubulin. We have a particular interest in the cytoskeleton, its chaperones and their role in determining cellular phenotypes associated with high level recombinant protein expression from mammalian cell expression systems.As studies into PhLP3 function have been largely carried out in non mammalian systems, we examined the effect of human PhLP3 over-expression and siRNA silencing using a single murine siRNA on both tubulin and actin systems in mammalian Chinese hamster ovary (CHO cell lines. We show that over-expression of PhLP3 promotes an imbalance of α and β tubulin subunits, microtubule disassembly and cell death. In contrast, β-actin levels are not obviously perturbed. On-the-other-hand, RNA silencing of PhLP3 increases RhoA-dependent actin filament formation and focal adhesion formation and promotes a dramatic elongated fibroblast-like change in morphology. This was accompanied by an increase in phosphorylated MAPK which has been associated with promoting focal adhesion assembly and maturation. Transient overexpression of PhLP3 in knockdown experiments rescues cells from the morphological change observed during PhLP3 silencing but mitosis is perturbed, probably reflecting a tipping back of the balance of PhLP3 levels towards the overexpression state.Our results support the hypothesis that PhLP3 is important for the maintenance of β-tubulin levels in mammalian cells but also that its modulation can promote actin-based cytoskeletal remodelling by a mechanism linked with MAPK phosphorylation and RhoA-dependent changes. PhLP3 levels in mammalian cells are thus finely poised and represents a novel target for engineering industrially

  9. The effect of recommending a CPP-ACPF product on salivary and plaque pH levels in orthodontic patients: a randomized cross-over clinical trial.

    Science.gov (United States)

    Heshmat, Haleh; Banava, Sepideh; Mohammadi, Ebrahim; Kharazifard, Mohammad Javad; Mojtahedzadeh, Faramarz

    2014-11-01

    Along with their re-mineralizing capacity, calcium phosphopeptide-amorphous calcium phosphate products combined with fluoride (CPP-ACPF) could also be beneficial by neutralizing acidic salivary and plaque pH. The purpose was to evaluate the effect of CPP-ACPF on salivary and plaque pH in orthodontic patients. As a triple-blind, cross-over randomized trial, 30 orthodontic patients with fixed appliances (age range = 15.70 ± 4.08 years) were recruited and randomly assigned to two groups. A CPP-ACPF paste (MI Paste Plus, GC America, Alsip, IL) was used by group 1 (n = 15) and a placebo by group 2 (n = 15) for 1 month. After a 1 month washout period, patients used the alternative paste for another month. Plaque and salivary pH levels were measured at all before and after periods. By applying MI Paste Plus, the plaque pH increased from 5.81 ± 0.45 to 6.60 ± 0.38 (p salivary pH recordings, which were 6.72 ± 0.43 and 6.71 ± 0.38, respectively, remained statistically unchanged (p > 0.05). MI Paste Plus can be clinically beneficial in increasing plaque pH levels, but has no effect on the salivary pH.

  10. Taxonomy of Means and Ends in Aquaculture Production—Part 2: The Technical Solutions of Controlling Solids, Dissolved Gasses and pH

    Directory of Open Access Journals (Sweden)

    Bjorgvin Vilbergsson

    2016-09-01

    Full Text Available In engineering design, knowing the relationship between the means (technique and the end (desired function or outcome is essential. The means in Aquaculture are technical solutions like airlifts that are used to achive desired functionality (an end like controlling dissolved gasses. In previous work, the authors identified possible functions by viewing aquaculture production systems as transformation processes in which inputs are transformed by treatment techniques (means and produce outputs (ends. The current work creates an overview of technical solutions of treatment functions for both design and research purposes. A comprehensive literature review of all areas of technical solutions is identified and categorized into a visual taxonomy of the treatment functions for controlling solids, controlling dissolved gasses and controlling pH alkalinity and hardness. This article is the second in a sequence of four and partly presents the treatments functions in the taxonomy. The other articles in this series present complementary aspects of this research: Part 1, A transformational view on aquaculture and functions divided into input, treatment and output functions; Part 2, The current taxonomy paper; Part 3, The second part of the taxonomy; and Part 4, Mapping of the means (techniques for multiple treatment functions.

  11. Partitioning high-level waste from alkaline solution: A literature survey

    International Nuclear Information System (INIS)

    Marsh, S.F.

    1993-05-01

    Most chemical partitioning procedures are designed for acidic feed solutions. However, the high-level waste solutions in the underground storage tanks at US Department of Energy defense production sites are alkaline. Effective partitioning procedures for alkaline solutions could decrease the need to acidify these solutions and to dissolve the solids in acid, which would simplify subsequent processing and decrease the generation of secondary waste. The author compiles candidate technologies from his review of the chemical literature, experience, and personal contacts. Several of these are recommended for evaluation

  12. Fluidized-Bed Coating with Sodium Sulfate and PVA-TiO2, 2. Influence of Coating Solution Viscosity, Stickiness, pH, and Droplet Diameter on Agglomeration

    DEFF Research Database (Denmark)

    Hede, Peter Dybdahl; Bach, Poul; Jensen, Anker Degn

    2009-01-01

    In the first part of this study [Hede, P. D.; Bach, P.; Jensen, A. D. Ind. Eng. Chem. Res. 2009, 49, 1914], agglomeration regime maps were developed for two types of coatings: sodium sulfate and PVA-TiO2. It was observed here how the agglomeration tendency is always lower for the salt coating...... the PVA-TiO2 coating formulation and process to achieve a low tendency of agglomeration, similar to that of the salt coating process. The best results for the PVA-TiO2 solution are obtained by substituting the PVA-TiO2 in equal amounts with Neodol 23-6.5 and further reducing the pH value in the coating...

  13. Effect of diet phase change, dietary Ca and P level and phytase on bird performance and real-time gizzard pH measurements.

    Science.gov (United States)

    Lee, S A; Dunne, J; Mottram, T; Bedford, M R

    2017-06-01

    In this study, a novel capsule technique was used to capture real-time pH readings from the gizzard over several hours, in response to different dietary treatments. 1. The first experiment was a preliminary study into capsule administration and pH recordings using 9 male Ross 308 broilers from 20 d. In the second experiment, broilers (576) were fed in two phases (0-21 and 21-42 d) with 4 treatment groups; low and adequate Ca and AvP diets with and without Quantum Blue phytase (1500 FTU/kg). Capsules were administered to 8 birds from each treatment group, pre and post diet phase change, with readings captured over a 2.5 h period. 2. Phytase addition improved body weight gain (BWG) and feed conversion ratio (FCR) of birds fed low dietary Ca, while having no significant effect on birds fed adequate Ca diets. Unexpectantly, diets with higher Ca levels gave a lower average gizzard pH compared to the low Ca diet. Phytase addition, irrespective of Ca level, increased average gizzard pH. Fluctuations in gizzard pH (0.6-3.8) were observed across all treatment groups. Higher frequencies of pH readings below pH 1.0 were seen in birds fed an adequate Ca diet and with phytase supplementation of a low Ca diet. 3. These results signify the potential use of capsule techniques to monitor real-time pH changes. The implication on gastric protein and fibre hydrolysis as a result of large fluctuations in pH should be considered.

  14. Evaluation of citric acid and GDL in the recovery at different pH levels of Clostridium sporogenes PA 3679 spores subjected to HTST treatment conditions.

    Science.gov (United States)

    Silla Santos, M H; Torres Zarzo, J

    1996-04-01

    Spores of Clostridium sporogenes PA 3679 were treated at different temperatures (121, 126, 130 and 135 degrees C) in white asparagus purée (pH 5.8) and acidified with glucono-delta-lactone (GDL) and citric acid to pH levels of 5.5, 5.0 and 4.5. Afterwards, the spores were recovered in MPA3679 medium in various conditions: unacidified (pH 7.5), acidified with GDL (500 ppm) and acidified with citric acid (500 and 250 ppm) to pH levels of 6.5, 6.0 and 5.0. The results indicated that the pH levels, concentration and type of acid used act synergistically rather than independently. Citric acid has a stronger inhibiting effect than GDL on the recovery of C. sporogenes PA 3679 spores. At the higher heat treatments (130 and 135 degrees C) the major injury on the spores sensitize more than against the acids and low pH values.

  15. A STUDY OF THE PRESSURE SOLUTION AND DEFORMATION OF QUARTZ CRYSTALS AT HIGH pH AND UNDER HIGH STRESS

    Directory of Open Access Journals (Sweden)

    JUNG-HAE CHOI

    2013-02-01

    Full Text Available Bentonite is generally used as a buffer material in high-level radioactive waste disposal facilities and consists of 50% quartz by weight. Quartz strongly affects the behavior of bentonite over very long periods. For this reason, quartz dissolution experiment was performed under high-pressure and high-alkalinity conditions based on the conditions found in a high-level radioactive waste disposal facility located deep underground. In this study, two quartz dissolution experiments were conducted on 1 quartz beads under low-pressure and high-alkalinity conditions and 2 a single quartz crystal under high-pressure and high-alkalinity conditions. Following the experiments, a confocal laser scanning microscope (CLSM was used to observe the surfaces of experimental samples. Numerical analyses using the finite element method (FEM were also performed to quantify the deformation of contact area. Quartz dissolution was observed in both experiments. This deformation was due to a concentrated compressive stress field, as indicated by the quartz deformation of the contact area through the FEM analysis. According to the numerical results, a high compressive stress field acted upon the neighboring contact area, which showed a rapid dissolution rate compared to other areas of the sample.

  16. Ex situ characterization of metallurgical inclusions in X100 pipeline steel before and after immersion in a neutral pH bicarbonate solution

    Energy Technology Data Exchange (ETDEWEB)

    Li, Yingbo; Liu, Jie [Key Laboratory of Advanced Ceramics and Machining Technology (Ministry of Education), School of Materials Science and Engineering, Tianjin University, Tianjin 300072 (China); Deng, Yida [Tianjin Key Laboratory of Composite and Functional Materials, Tianjin University, Tianjin 300072 (China); Han, Xiaopeng [Key Laboratory of Advanced Ceramics and Machining Technology (Ministry of Education), School of Materials Science and Engineering, Tianjin University, Tianjin 300072 (China); Hu, Wenbin [Key Laboratory of Advanced Ceramics and Machining Technology (Ministry of Education), School of Materials Science and Engineering, Tianjin University, Tianjin 300072 (China); Tianjin Key Laboratory of Composite and Functional Materials, Tianjin University, Tianjin 300072 (China); Zhong, Cheng, E-mail: cheng.zhong@tju.edu.cn [Key Laboratory of Advanced Ceramics and Machining Technology (Ministry of Education), School of Materials Science and Engineering, Tianjin University, Tianjin 300072 (China)

    2016-07-15

    The initiation of corrosion pits in pipeline steels plays an important role in the development of stress corrosion cracking. In order to reveal the effect of inclusions on corrosion initiation sites and also to clarify contradictory results from previous literature, we proposed an ex situ characterization method that is allowed to characterize exactly the same inclusion or location of the surface of steel before and after corrosion tests. The time-dependent corrosion behaviour of the inclusions and the surrounding X100 steel matrix at the same area before and after early stage immersion in a near-neutral pH bicarbonate solution was investigated by ex situ scanning electron microscopy (SEM), energy-dispersive X-ray (EDX) analysis and localized electrochemical impedance spectroscopy (LEIS). The sizes of most inclusions in X100 steel are below 3 μm. The results challenge the long-held opinion of previous work that corrosion pit initiations are related with the inclusions. It has been found that most of the inclusions remain stable (intact) during the whole testing time although severe corrosion occurs on the matrix of the steel. The chemical composition of the inclusion greatly affects the chemical stability of the inclusion. SiO{sub 2} inclusions and complex inclusions with a high SiO{sub 2} content remain intact although obvious general corrosion occurs on the steel matrix under the investigated immersion period. Inclusions with little Si, such as Al–Mg–Ca–O enriched inclusions, totally disappear after certain immersion time. During the immersion, the corrosion product tends to deposit at the interstice between the inclusion and steel matrix. - Highlights: • Ex situ characterization of metallurgical inclusions in X100 pipeline steel. • The pipeline steel was immersed in neutral pH bicarbonate solution. • Majority of inclusions remain stable during the whole testing time. • The chemical stability of metallurgical inclusions depends on the SiO{sub 2

  17. Ex situ characterization of metallurgical inclusions in X100 pipeline steel before and after immersion in a neutral pH bicarbonate solution

    International Nuclear Information System (INIS)

    Li, Yingbo; Liu, Jie; Deng, Yida; Han, Xiaopeng; Hu, Wenbin; Zhong, Cheng

    2016-01-01

    The initiation of corrosion pits in pipeline steels plays an important role in the development of stress corrosion cracking. In order to reveal the effect of inclusions on corrosion initiation sites and also to clarify contradictory results from previous literature, we proposed an ex situ characterization method that is allowed to characterize exactly the same inclusion or location of the surface of steel before and after corrosion tests. The time-dependent corrosion behaviour of the inclusions and the surrounding X100 steel matrix at the same area before and after early stage immersion in a near-neutral pH bicarbonate solution was investigated by ex situ scanning electron microscopy (SEM), energy-dispersive X-ray (EDX) analysis and localized electrochemical impedance spectroscopy (LEIS). The sizes of most inclusions in X100 steel are below 3 μm. The results challenge the long-held opinion of previous work that corrosion pit initiations are related with the inclusions. It has been found that most of the inclusions remain stable (intact) during the whole testing time although severe corrosion occurs on the matrix of the steel. The chemical composition of the inclusion greatly affects the chemical stability of the inclusion. SiO_2 inclusions and complex inclusions with a high SiO_2 content remain intact although obvious general corrosion occurs on the steel matrix under the investigated immersion period. Inclusions with little Si, such as Al–Mg–Ca–O enriched inclusions, totally disappear after certain immersion time. During the immersion, the corrosion product tends to deposit at the interstice between the inclusion and steel matrix. - Highlights: • Ex situ characterization of metallurgical inclusions in X100 pipeline steel. • The pipeline steel was immersed in neutral pH bicarbonate solution. • Majority of inclusions remain stable during the whole testing time. • The chemical stability of metallurgical inclusions depends on the SiO_2 content.

  18. The effect of pH on the corrosion behavior of intermetallic compounds Ni{sub 3}(Si,Ti) and Ni{sub 3}(Si,Ti) + 2Mo in sodium chloride solutions

    Energy Technology Data Exchange (ETDEWEB)

    Priyotomo, Gadang, E-mail: gada001@lipi.go.id; Nuraini, Lutviasari, E-mail: Lutviasari@gmail.com [Research Center for Metallurgy and Material, Indonesian Institute of Sciences, Kawasan PUSPIPTEK Gd.474, Setu, Tangerang Selatan, Banten 15314 (Indonesia); Kaneno, Yasuyuki, E-mail: kaneno@mtr.osakafu-u.ac.id [Department of Materials Science, Graduate School of Engineering, Osaka Prefecture University, 1-1 Gakuen-cho, Sakai, Osaka 599-8531 (Japan)

    2015-12-29

    The corrosion behavior of the intermetallic compounds, Ni{sub 3}(Si,Ti) (L1{sub 2}: single phase) and Ni{sub 3}(Si,Ti) + 2Mo (L1{sub 2} and (L12 + Ni{sub ss}) mixture region), has been investigated using an immersion test, electrochemical method and surface analytical method (SEM; scanning electron microscope and EDAX: Energy Dispersive X-ray) in 0.5 kmol/m{sup 3} NaCl solutions at various pH. The corrosion behavior of nickel alloy C-276 was studied under the same experimental conditions as a reference. It was found that the uniform attack was observed on Ni{sub 3}(Si,Ti) for the immersion test at lower pH, while the pitting attack was observed on this compound for this test at neutral solution. Furthermore, Ni{sub 3}(Si,Ti)+2Mo had the preferential dissolution of L1{sub 2} compared to (L1{sub 2} + Ni{sub ss}) mixture region at lower pH, while pitting attack occurred in (L1{sub 2} + Ni{sub ss}) mixture region at neutral solution. For both intermetallic compounds, the magnitude of pitting and uniform attack decrease with increasing pH of solutions. From the immersion test and polarization curves, the corrosion resistance of Ni{sub 3}(Si,Ti)+2Mo is lower than that of Ni{sub 3}(Si,Ti), while the nickel alloy C-276 is the highest one at various pH of solutions. On the other hand, in the lower pH of solutions, the corrosion resistance of tested materials decreased significantly compared to those in neutral and higher pH of solutions.

  19. Solution pH and oligoamine molecular weight dependence of the transition from monolayer to multilayer adsorption at the air-water interface from sodium dodecyl sulfate/oligoamine mixtures.

    Science.gov (United States)

    Halacheva, S S; Penfold, J; Thomas, R K; Webster, J R P

    2013-05-14

    Neutron reflectivity and surface tension have been used to investigate the solution pH and oligoamine molecular weight dependence of the adsorption of sodium dodecyl sulfate (SDS)/oligoamine mixtures at the air-water interface. For diethylenetriamine, triamine, or triethylenetetramine, tetramine mixed with SDS, there is monolayer adsorption at pH 7 and 10, and multilayer adsorption at pH 3. For the slightly higher molecular weight tetraethylenepentamine, pentamine, and pentaethylenehexamine, hexamine, the adsorption is in the form of a monolayer at pH 3 and multilayers at pH 7 and 10. Hence, there is a pH driven transition from monolayer to multilayer adsorption, which shifts from low pH to higher pH as the oligoamine molecular weight increases from tetramine to pentamine. This results from the relative balance between the electrostatic attraction between the SDS and amine nitrogen group which decreases as the charge density decreases with increasing pH, the ion-dipole interaction between the amine nitrogen and SDS sulfate group which is dominant at higher pH, and the hydrophobic interalkyl chain interaction between bound SDS molecules which changes with oligoamine molecular weight.

  20. Effect of temperature, pH, and oxygen level on the multiplication of naturally occurring Legionella pneumophila in potable water.

    Science.gov (United States)

    Wadowsky, R M; Wolford, R; McNamara, A M; Yee, R B

    1985-05-01

    A water culture containing naturally occurring Legionella pneumophila and associated microbiota was maintained in the laboratory by serially transferring the culture in tap water which had been sterilized by membrane filtration. Successful maintenance of the water culture depended upon transferring the culture when the growth of L. pneumophila was in the late-exponential to early-stationary phase. The water culture was used as a source of naturally occurring bacteria to determine some of the parameters which affect the multiplication of L. pneumophila in tap water. Naturally occurring L. pneumophila multiplied at a temperature between 25 and 37 degrees C, at pH levels of 5.5 to 9.2, and at concentrations of dissolved oxygen of 6.0 to 6.7 mg/liter. Multiplication did not occur in tap water which contained less than 2.2 mg of dissolved oxygen per liter. An association was observed between the multiplication of L. pneumophila and the non-Legionellaceae bacteria which were also present in the water culture. The method of preserving naturally occurring L. pneumophila and associated microbiota may facilitate studies on the symbiosis of L. pneumophila with other microorganisms.

  1. Low levels of iron enhance UV/H2O2 efficiency at neutral pH.

    Science.gov (United States)

    Ulliman, Sydney L; McKay, Garrett; Rosario-Ortiz, Fernando L; Linden, Karl G

    2018-03-01

    While the presence of iron is generally not seen as favorable for UV-based treatment systems due to lamp fouling and decreased UV transmittance, we show that low levels of iron can lead to improvements in the abatement of chemicals in the UV-hydrogen peroxide advanced oxidation process. The oxidation potential of an iron-assisted UV/H 2 O 2 (UV 254  + H 2 O 2  + iron) process was evaluated at neutral pH using iron levels below USEPA secondary drinking water standards (UV/H 2 O 2 systems. The effects of iron species (Fe 2+ and Fe 3+ ), iron concentration (0-0.3 mg/L), H 2 O 2 concentration (0-10 mg/L) and background water matrix (low-carbon tap (LCT) and well water) on HO production and compound removal were examined. Iron-assisted UV/H 2 O 2 efficiency was most influenced by the target chemical and the water matrix. Added iron to UV/H 2 O 2 was shown to increase the steady-state HO concentration by approximately 25% in all well water scenarios. While CBZ removal was unchanged by iron addition, 0.3 mg/L iron improved NDMA removal rates in both LCT and well water matrices by 15.1% and 4.6% respectively. Furthermore, the combination of UV/Fe without H 2 O 2 was also shown to enhance NDMA removal when compared to UV photolysis alone indicating the presence of degradation pathways other than HO oxidation. Copyright © 2017 Elsevier Ltd. All rights reserved.

  2. Changes in EC , pH and in the concentrations of nitrate, ammonium, sodium and chlorine in the drainage solution of a crop of roses on substrates with drainage recycling

    Directory of Open Access Journals (Sweden)

    Mariela Rodríguez

    2012-08-01

    Full Text Available The rose cultivation system has been changing from soil to substrate on the Plateau of Bogota. The objective of this study was the monitoring of the EC, pH, and the levels of nitrate, ammonium, sodium and chlorine in a drainage solution in a crop of roses with substrates based on burnt rice husk and coconut fiber. The Charlotte rose variety grafted onto ‘Natal Briar’ was planted in a greenhouse located in one of the SENA facilities in Mosquera (Colombia; with a density of 6.5 plants/ m². For this experiment, a split plot design was used arranged in randomized blocks with a three-level recirculating system (0, 50 and 100% on the substrates 100% burnt rice husk; 65% burnt rice husk plus 35% coconut fiber; and 35% burnt rice husk plus 65% coconut fiber, repeated three times. The EC decreased from 2.7 to 1.3 mS cm-1 within weeks 2 and 5 which demonstrated an increase of mineral consumption by the plants. The pH levels dropped from 7.46 to 6.27 within weeks 3 to 8 and then increased to 7.39 within weeks 8 to 12. Nitrate concentrations showed a decreasing trend in recirculation treatments within weeks 2 to 12. A lower ammonium concentration was observed at week 4 in treatments with and without recirculation during the vegetative stage. The levels of sodium and chloride increased in treatments with a recirculation system, without signs of toxicity

  3. The level of heat shock protein 90 in pig Longissimus dorsi muscle and its relationship with meat pH and quality.

    Science.gov (United States)

    Zhang, Muhan; Wang, Daoying; Geng, Zhiming; Bian, Huan; Liu, Fang; Zhu, Yongzhi; Xu, Weimin

    2014-12-15

    The 90 kDa heat shock protein (HSP90) is a molecular chaperone that participates in various cellular processes, the role and significance of HSP90 in postmortem muscle though remains unclear. In the present study, pig Longissimus dorsi muscles, categorized into three pH groups, were tested for HSP90 levels and meat quality parameters (i.e. water holding capacity, colour, tenderness and lipid oxidation). The muscles with a high initial pH (pHi) group (pH>6.4) possessing the greatest water holding capacity and lightness, contained the highest HSP90 level, followed by intermediate (6.0-6.4) and low pHi groups (pHwater retention of meat and may be involved in postmortem meat quality development. Copyright © 2014 Elsevier Ltd. All rights reserved.

  4. Formation of M-Like Intermediates in Proteorhodopsin in Alkali Solutions (pH ≥ ∼8.5) Where the Proton Release Occurs First in Contrast to the Sequence at Lower pH.

    Science.gov (United States)

    Tamogami, Jun; Sato, Keitaro; Kurokawa, Sukuna; Yamada, Takumi; Nara, Toshifumi; Demura, Makoto; Miyauchi, Seiji; Kikukawa, Takashi; Muneyuki, Eiro; Kamo, Naoki

    2016-02-23

    Proteorhodopsin (PR) is an outward light-driven proton pump observed in marine eubacteria. Despite many structural and functional similarities to bacteriorhodopsin (BR) in archaea, which also acts as an outward proton pump, the mechanism of the photoinduced proton release and uptake is different between two H(+)-pumps. In this study, we investigated the pH dependence of the photocycle and proton transfer in PR reconstituted with the phospholipid membrane under alkaline conditions. Under these conditions, as the medium pH increased, a blue-shifted photoproduct (defined as Ma), which is different from M, with a pKa of ca. 9.2 was produced. The sequence of the photoinduced proton uptake and release during the photocycle was inverted with the increase in pH. A pKa value of ca. 9.5 was estimated for this inversion and was in good agreement with the pKa value of the formation of Ma (∼ 9.2). In addition, we measured the photoelectric current generated by PRs attached to a thin polymer film at varying pH. Interestingly, increases in the medium pH evoked bidirectional photocurrents, which may imply a possible reversal of the direction of the proton movement at alkaline pH. On the basis of these findings, a putative photocycle and proton transfer scheme in PR under alkaline pH conditions was proposed.

  5. Estimation and Comparison of Salivary Calcium, Phosphorous, Alkaline Phosphatase and pH Levels in Periodontal Health and Disease: A Cross-sectional Biochemical Study.

    Science.gov (United States)

    Patel, Rufi Murad; Varma, Siddhartha; Suragimath, Girish; Zope, Sameer

    2016-07-01

    In oral diagnostics there is a great challenge to determine biomarkers for screening and evaluating the disease activity. Biomarkers can also serve as a useful tool to measure the efficacy of the therapy. To evaluate and compare the levels of salivary calcium, phosphorous, alkaline phosphatase and pH levels in periodontally healthy subjects and patients with gingivitis and periodontitis. The present study consisted of 150 subjects aged between 20-45 years who were divided into three groups; periodontally healthy, gingivitis and chronic periodontitis. Prior to the clinical examination the demographic details, relevant information of the subject, gingival index, plaque index, Oral Hygiene Index (OHI) and pH were recorded. Biochemical assay of saliva i.e., inorganic calcium, phosphorous and alkaline phosphatase were estimated by colorimetric method. ANOVA and Tukey's test were applied for statistical analysis. The mean levels of biomarkers studied were; inorganic calcium (12.55μg/dl), phosphorous (14.50μg/dl), alkaline phosphatase (49.62μg/dl) and pH (11.65). There was a gradual increase in these levels as the condition progressed from health to gingivitis or periodontitis which was statistically significant at psalivary calcium, phosphorous, alkaline phosphatase and pH can be considered for evaluating the diagnosis and prognosis of periodontal tissues in disease and health.

  6. Lactate versus pH levels in fetal scalp blood during labor--using the Lactate Scout System

    DEFF Research Database (Denmark)

    Lundin, Ingeborg Christina Rørbye; Perslev, Anette; Nickelsen, Carsten Nahne Amtoft

    2016-01-01

    OBJECTIVE: To assess if lactate measured with the Scout Lactate System is a reliable alternative to pH in intrapartum monitoring of the fetus. METHODS: A prospective study analyzing (1) the correlation between scalp lactate measured by the Scout Lactate System and the Automatic Blood Laboratory (...

  7. Carbon steel corrosion under anaerobic-aerobic cycling conditions in near-neutral pH saline solutions - Part 1: Long term corrosion behaviour

    International Nuclear Information System (INIS)

    Sherar, B.W.A.; Keech, P.G.; Shoesmith, D.W.

    2011-01-01

    Highlights: → Anaerobic-aerobic cycling on pipeline steel forms two distinct surface morphologies. → Seventy-five percentage of the surface was covered by a black, compact layer ∼4.5 μm thick. → A tubercle, ∼3 to 4 mm in cross section, covered the remaining 25% of surface. → The tubercle cross section showed a single large pit ∼275 μm deep. - Abstract: The influence of anaerobic-aerobic cycling on pipeline steel corrosion was investigated in near-neutral carbonate/sulphate/chloride solution (pH 9) over 238 days. The corrosion rate increased and decreased as exposure conditions were switched between redox conditions. Two distinct corrosion morphologies were observed. The majority of the surface corroded uniformly to produce a black magnetite/maghemite layer approximately 4.5 μm thick. The remaining surface was covered with an orange tubercle, approximately 3-4 mm in cross section. Analysis of the tubercle cross section revealed a single large pit approximately 275 μm deep. Repeated anaerobic-aerobic cycling localized the corrosion process within this tubercle-covered pit.

  8. The effect of aerobic corrosion on anaerobically-formed sulfide layers on carbon steel in dilute near-neutral pH saline solutions

    International Nuclear Information System (INIS)

    Sherar, B.W.A.; Keech, P.G.; Shoesmith, D.W.

    2013-01-01

    Highlights: •The corrosion rate is low when steel is exposed to anaerobic conditions (pH = 8.9). •An anaerobic corrosion with sulfide to aerobic switch increases the corrosion rate. •Aerobic conditions leads to corrosion and oxide deposition beneath FeS. •Continual air exposure leads to the blistering of the original FeS film. -- Abstract: The aerobic corrosion of pipeline steel was investigated in an aqueous sulfide solution by monitoring the corrosion potential and periodically measuring the polarization resistance. The properties and composition of the corrosion product deposits formed were determined using scanning electron microscopy, energy dispersive X-ray analysis, and Raman spectroscopy. The establishment of aerobic conditions leads to corrosion and (oxyhydr)oxide deposition beneath the anaerobically-formed mackinawite film originally present on the steel surface. This leads to blistering and spalling of the sulfide film. Chemical conversion of the mackinawite to Fe(III) (oxyhydr)oxides also occurs but is a relatively slow reaction

  9. Standard Practice for Use of Mattsson's Solution of pH 7.2 to Evaluate the Stress- Corrosion Cracking Susceptibility of Copper-Zinc Alloys

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2011-01-01

    1.1 This practice covers the preparation and use of Mattsson's solution of pH 7.2 as an accelerated stress-corrosion cracking test environment for brasses (copper-zinc base alloys). The variables (to the extent that these are known at present) that require control are described together with possible means for controlling and standardizing these variables. 1.2 This practice is recommended only for brasses (copper-zinc base alloys). The use of this test environment is not recommended for other copper alloys since the results may be erroneous, providing completely misleading rankings. This is particularly true of alloys containing aluminum or nickel as deliberate alloying additions. 1.3 This practice is intended primarily where the test objective is to determine the relative stress-corrosion cracking susceptibility of different brasses under the same or different stress conditions or to determine the absolute degree of stress corrosion cracking susceptibility, if any, of a particular brass or brass component ...

  10. All-in-One Wafer-Level Solution for MMIC Automatic Testing

    Directory of Open Access Journals (Sweden)

    Xu Ding

    2018-04-01

    Full Text Available In this paper, we present an all-in-one wafer-level solution for MMIC (monolithic microwave integrated circuit automatic testing. The OSL (open short load two tier de-embedding, the calibration verification model, the accurate PAE (power added efficiency testing, and the optimized vector cold source NF (noise figure measurement techniques are integrated in this solution to improve the measurement accuracy. A dual-core topology formed by an IPC (industrial personal computer and a VNA (vector network analyzer, and an automatic test software based on a three-level driver architecture, are applied to enhance the test efficiency. The benefit from this solution is that all the data of a MMIC can be achieved in only one contact, which shows state-of-the-art accuracy and efficiency.

  11. Evaluation method of iodine re-evolution from an in-containment water pool after a loss of coolant accident, Part I: pH estimation of a solution with various chemicals

    International Nuclear Information System (INIS)

    Kim, Tae Hyeon; Jeong, Ji Hwan

    2016-01-01

    Highlights: • It is required to evaluate re-evolved iodine from sump water after LOCA. • pH evaluation based on Gibbs free energy minimization. • Program was developed to evaluate chemical equilibrium and pH solutions. • Predictions are in good agreement with experimental data. - Abstract: Radioactive iodine, which is released into the atmosphere of the containment building, is absorbed into the containment spray water and dissolved to be ionized. This iodine-rich water is then transported to the in-containment refueling water storage tank (IRWST) in APR1400 nuclear power plants. When the pH of the water is below 7, the dissolved iodine converts to molecular iodine and re-evolves from the water and returns to the atmosphere. A series of studies have been conducted in order to evaluate the iodine re-evolution from the IRWST. This study consists of two parts: the pH evaluation method and the evaluation of the iodine re-evolution. This paper presents the first part, i.e. the pH evaluation method. The equilibrium concentrations of various chemicals in a solution are determined at the minimum Gibbs’ free energy. This method is useful for complex reactant problems rather than equilibrium constants method because the latter method requires numerous equilibrium constants and there might be missing equilibrium constants associated with the solution. The calculated pH values of solutions are compared with the experimental measurements in order to validate this method and the thermodynamic data of the chemicals incorporated into the program. The estimated values for solutions are in good agreement with the experimental measurements within a difference of less than 3.3%.

  12. Solutions of the two-level problem in terms of biconfluent Heun functions

    Energy Technology Data Exchange (ETDEWEB)

    Ishkhanyan, Artur [Engineering Center of Armenian National Academy of Sciences, Ashtarak (Armenia)]. E-mail: artur@ec.sci.am; Suominen, Kalle-Antti [Helsinki Institute of Physics, Helsinki (Finland); Department of Applied Physics, University of Turku, Turku (Finland)

    2001-08-17

    Five four-parametric classes of quantum mechanical two-level models permitting solutions in terms of the biconfluent Heun function are derived. Three of these classes are generalizations of the well known classes of Landau-Zener, Nikitin and Crothers. It is shown that two other classes describe super- and sublinear and essentially nonlinear level crossings, as well as processes with three crossing points. In particular, these classes include two-level models where the field amplitude is constant and the detuning varies as {delta}{sub 0}t+{delta}{sub 2}t{sup 3} or {approx}t{sup 1/3}. For the essentially nonlinear cubic-crossing model, {delta}{sub t}{approx}{delta}{sub 2}t{sup 3}, the general solution of the two-level problem is shown to be expressed as series of confluent hypergeometric functions. (author)

  13. Exact Solution of the Two-Level System and the Einstein Solid in the Microcanonical Formalism

    Science.gov (United States)

    Bertoldi, Dalia S.; Bringa, Eduardo M.; Miranda, E. N.

    2011-01-01

    The two-level system and the Einstein model of a crystalline solid are taught in every course of statistical mechanics and they are solved in the microcanonical formalism because the number of accessible microstates can be easily evaluated. However, their solutions are usually presented using the Stirling approximation to deal with factorials. In…

  14. Pore solution chemistry of simulated low-level liquid waste incorporated in cement grouts

    International Nuclear Information System (INIS)

    Kruger, A.A.

    1995-12-01

    Expressed pore solutions from simulated low level liquid waste cement grouts cured at room temperature, 50 degree C and 90 degree C for various duration were analyzed by standard chemical methods and ion chromatography. The solid portions of the grouts were formulated with portland cement, fly ash, slag, and attapulgite clay in the ratios of 3:3:3:1. Two different solutions simulating off-gas condensates expected from vitrification of Hanford low level tank wastes were made. One is highly alkaline and contains the species Na + , P0 4 3- , N0 2 - , NO 3 - and OH - . The other is carbonated and contains the species, Na + , PO 4 3- , NO 2 - , NO 3 - , and CO 3 2- . In both cases phosphate rapidly disappeared from the pore solution, leaving behind sodium in the form of hydroxide. The carbonates were also removed from the pore solution to form calcium carbonate and possibly calcium monocarboaluminate. These reactions resulted in the increase of hydroxide ion concentration in the early period. Subsequently there was a significant reduction OH - and Na + ion concentrations. In contrast high concentration of N0 2 - and N0 3 - were retained in the pore solution indefinitely

  15. Experimental study of trace metal chemistry in soft-water lakes at different pH levels

    Energy Technology Data Exchange (ETDEWEB)

    Jackson, T A; Kipphut, G; Hesslein, R H; Schindler, D W

    1980-03-01

    The biogeochemistry of Hg, Zn, Co, Fe, Mn, Cr, V, Th, Ba, Cs, As, and Se in two soft-water lakes of the Canadian shield was investigated. The residence times of the radionuclides in the water were determined, and the partitioning of the nuclides among different metal-binding agents in the water and sediments was studied. Metals of high crystal field stabilization energy, high electronegativity, or small ionic radius were most readily scavenged by greater than 0.45 micrometer suspended particles and dispersed colloids in the water, disappeared most rapidly from the water column, and were preferentially accumulated by sedimentary binding agents, including organic substances. Hg was removed fairly rapidly from the water at pH 6.7-6.8 owing to its high electronegativity but was removed more slowly than any other metal at pH 5.1 owing to its large ionic radius. Acidification of lake water to pH 5.1 interfered with accumulation of Hg and other metals by organic ooze. Acidification also lowered the concentration of extractable colloidal phosphate in the ooze but had no effect on extractable orthophosphate content. 45 references, 10 figures, 4 tables.

  16. Dependency of the band gap of electrodeposited Copper oxide thin films on the concentration of copper sulfate (CuSO4.5H2O) and pH in bath solution for photovoltaic applications

    KAUST Repository

    Islam, Md. Anisul

    2016-03-10

    In this study, Copper oxide thin films were deposited on copper plate by electrodeposition process in an electrolytic bath containing CuSO4.5H2O, 3M lactic acid and NaOH. Copper oxide films were electrodeposited at different pH and different concentration of CuSO4.5H2O and the optical band gap was determined from their absorption spectrum which was obtained from UV-Vis absorption spectroscopy. It was found that copper oxide films which were deposited at low concentration of CuSO4.5H2O have higher band gap than those deposited at higher bath concentration. The band gap of copper oxide films also significantly changes with pH of the bath solution. It was also observed that with the increase of the pH of bath solution band gap of copper oxide film decreased. © 2015 IEEE.

  17. Assessment of Material Solutions of Multi-level Garage Structure Within Integrated Life Cycle Design Process

    Science.gov (United States)

    Wałach, Daniel; Sagan, Joanna; Gicala, Magdalena

    2017-10-01

    The paper presents an environmental and economic analysis of the material solutions of multi-level garage. The construction project approach considered reinforced concrete structure under conditions of use of ordinary concrete and high-performance concrete (HPC). Using of HPC allowed to significant reduction of reinforcement steel, mainly in compression elements (columns) in the construction of the object. The analysis includes elements of the methodology of integrated lice cycle design (ILCD). By making multi-criteria analysis based on established weight of the economic and environmental parameters, three solutions have been evaluated and compared within phase of material production (information modules A1-A3).

  18. Structural alterations in embryos and alevins of the Atlantic salmon, Salmo salar 1. , induced by continuous or short-term exposure to acidic levels of pH

    Energy Technology Data Exchange (ETDEWEB)

    Daye, P.G.; Garside, E.T.

    1980-01-01

    Embryos of the Atlantic Salmon, salmo salar l., were incubated continuously from fertilization, at pH 6.8 (control), 5.0, 4.5, 4.3, 4.0, and 3.7, at 5-6 degrees C. The subsequent alvins in these environments were maintained at these levels for 40 days after hatching. Generally, lethal and sublethal injuries were separable only as to degree and distribution. Sublethal alterations occurred in the integument, gill blood, and blood vascular structures of all live alevins incubated at pH 5.0 and lower. At pH 4.5 and lower, injuries also occurred in brain, optic retina, kidney, and spleen. Some tissue regeneration occurred in the embryonal rudimentary integument at pH 4.5 and lower. Regeneration also occurred but to a lesser degree in pseudobranch, kidney, spleen, and erythrocytes. Injury of the integument was the apparent cause of death in prehatching embryos since it is the major site of respiration and ion exchange. As gills expand in posthatching alevins, they assume these functions and destruction of branchial epithelium then becomes the prime cause of death. The nature of cell injury and consequent dysgenesis at tissue and organ levels are not ascribable uniquely to acidic stress. Some injuries are similar to those caused variously by heavy metals, detergents, halogenated organic compounds, some petroleum fractions, and chronic and acute high temperature in postalevin stages of several species of fish.

  19. Influence of the Dentinal Wall on the pH of Sodium Hypochlorite during Root Canal Irrigation

    NARCIS (Netherlands)

    Macedo, Ricardo Gomes; Herrero, Noemi Pascual; Wesselink, Paul; Versluis, Michel; van der Sluis, Luc

    Introduction: The purpose of this study was to evaluate the influence of dentin on the pH levels of different concentrations of sodium hypochlorite (NaOCl) solutions over time and to evaluate if preconditioning of dentin with 17% EDTA or agitation of the NaOCl solution influences these pH levels.

  20. Removal of radioruthenium from alkaline intermediate level radioactive waste solution : a laboratory investigation

    International Nuclear Information System (INIS)

    Samanta, S.K.; Theyyunni, T.K.

    1994-01-01

    Various methods were investigated in the laboratory for the removal of radioruthenium from alkaline intermediate level radioactive waste solutions of reprocessing plant origin. The methods included batch equilibration with different ion exchangers and sorbents, column testing and chemical precipitation. A column method using zinc-activated carbon mixture and a chemical precipitation method using ferrous salt along with sodium sulphite were found to be promising for plant scale application. (author). 10 refs., 3 figs., 7 tabs

  1. PH sensor

    OpenAIRE

    Artero, C.; Nogueras Cervera, Marc; Manuel Lázaro, Antonio

    2012-01-01

    This paper presents a design of a marine instrument for the measurement of pH in seawater. The measurement system consists of a pH electrode connected to the underwater observatory OBSEA. The extracted data are useful for scientists researching ocean acidification. Peer Reviewed

  2. Influência do pH da solução extrativa no teor de antocianinas em frutos de morango Influence of the extraction solution pH on the content of anthocyanins in strawberry fruits

    Directory of Open Access Journals (Sweden)

    Celso Luiz Bordignon Jr.

    2009-03-01

    Full Text Available Nos últimos anos, os estudos sobre a composição química do fruto do morangueiro vêm ganhando destaque devido ao seu elevado consumo e às atividades biológicas atribuídas a ele. Além disso, os principais metabólitos secundários encontrados nesses frutos são as antocianinas, compostos responsáveis pela intensa coloração vermelha e amplamente utilizados como corantes naturais pela indústria alimentícia. Neste trabalho, foram preparados diferentes extratos de frutos de morango com a cultivar Oso Grande, com o intuito de verificar a influência do pH no perfil espectroscópico do extrato e no teor de antocianos. O extrato em pH 1,0 forneceu um perfil clássico para antocianinas na análise por espectroscopia no ultravioleta, assim como um maior teor de antocianinas nos frutos frescos devido a uma extração mais eficiente das substâncias de interesse.Recently, the study on the chemical composition of the strawberry fruit has been recognized in view of its increased consumption and biological activities. Moreover, the main secondary metabolites found in strawberry fruits are anthocyanins, which are the compounds responsible for the intense red color of the fruit and are widely used as natural colorants by the food industry. In this work, were prepared different extracts with strawberry fruits of the cultivar Oso Grande in order to verify the pH influence on the spectroscopic profile of the strawberry extracts and on the content of anthocyanins. The results indicate that at pH 1,0 the extract showed a classic profile to anthocyanins through ultraviolet spectra analysis and a higher content of anthocyanins in fresh fruits.

  3. Differences in functional traits between invasive and native Amaranthus species under simulated acid deposition with a gradient of pH levels

    Science.gov (United States)

    Wang, Congyan; Wu, Bingde; Jiang, Kun; Zhou, Jiawei

    2018-05-01

    Co-occurring invasive plant species (invaders hereafter) and natives receive similar or even the same environmental selection pressures. Thus, the differences in functional traits between natives and invaders have become widely recognized as a major driving force of the success of plant invasion. Meanwhile, increasing amounts of acid are deposited into ecosystems. Thus, it is important to elucidate the potential effects of acid deposition on the functional traits of invaders in order to better understand the potential mechanisms for the successful invasion. This study aims to address the differences in functional traits between native red amaranth (Amaranthus tricolor L.; amaranth hereafter) and invasive redroot pigweed (A. retroflexus L.; pigweed hereafter) under simulated acid deposition with a gradient of pH levels. Pigweed was significantly taller than amaranth under most treatments. The greater height of pigweed can lead to greater competitive ability for resource acquisition, particularly for sunlight. Leaf shape index of pigweed was also significantly greater than that of amaranth under all treatments. The greater leaf shape index of pigweed can enhance the efficiency of resource capture (especially sunlight capture) via adjustments to leaf shape and size. Thus, the greater height and leaf shape index of pigweed can significantly enhance its competitive ability, especially under acid deposition. Acid deposition of pH 5.6 significantly increased amaranth leaf width in the co-cultivation due to added nutrients. The pH 4.5 acid deposition treatment significantly increased the specific leaf area of amaranth in the monoculture compared with the pH 5.6 acid deposition treatment and the control. The main mechanism explaining this pattern may be due to acid deposition mediating a hormesis effect on plants, promoting plant growth. The values of the relative competition intensity between amaranth and pigweed for most functional traits were lower than zero under most

  4. Colorimetric study of malvidin-3-O-glucoside copigmented by phenolic compounds: The effect of molar ratio, temperature, pH, and ethanol content on color expression of red wine model solutions.

    Science.gov (United States)

    Zhang, Bo; Yang, Xue-Shan; Li, Ning-Ning; Zhu, Xia; Sheng, Wen-Jun; He, Fei; Duan, Chang-Qing; Han, Shun-Yu

    2017-12-01

    In the recent research, the copigmentations of malvidin-3-O-glucoside with eight types of phenolic copigments have been investigated. The influence of the pigment/copigment molar ratio, the reaction temperature, the pH and the ethanol content of solutions has been examined. The results showed that the copigmentation effect was dependent on not only the particular structures of the phenolic compounds but also the factors of the reaction systems. The increase of the copigment concentration can strengthen the copigmentation effect, improve the solution color, and enhance the red-purple features. Different temperatures had different influences on the copigmentation reactions. The destruction of the copigmentation complexes can result in the hypsochromic shift of the reaction solution when the temperature was higher than 20°C. The bathochromic shift of the solution gradually progressed with the increase of the pH value. A significant copigmentation feature was spotted when pH reached 3.0, which demonstrates obvious red-purple characterization. The addition of the ethanol weakened the copigmentation effect. According to measurement through color analysis, it was found that the color differences caused by ethanol in red wine were typically attributed to quantitative changes. Remarkably, all of the above delicate color deviations caused by the structural or environmental factors can be precisely and conveniently depicted via the CIELAB space analysis. Copyright © 2017 Elsevier Ltd. All rights reserved.

  5. New formulae for solutions of quantum Knizhnik-Zamolodchikov equations on level-4

    International Nuclear Information System (INIS)

    Boos, Hermann; Korepin, Vladimir; Smirnov, Feodor

    2004-01-01

    We present a new form of solution to the quantum Knizhnik-Zamolodchikov equation [qKZ] on level-4 in a special case corresponding to the Heisenberg XXX spin chain. Our form is equivalent to the integral representation obtained by Jimbo and Miwa in 1996 [7]. An advantage of our form is that it is reduced to the product of single integrals. This fact is deeply related to a cohomological nature of our formulae. Our approach is also based on the deformation of hyper-elliptic integrals and their main property-deformed Riemann bilinear relation. Jimbo and Miwa also suggested a nice conjecture which relates solution of the qKZ on level-4 to any correlation function of the XXX model. This conjecture, together with our form of solution to the qKZ, makes it possible to prove a conjecture that any correlation function of the XXX model can be expressed in terms of the Riemann zeta-function at odd arguments and rational coefficients. This issue will be discussed in our next publication

  6. Exceptionally crystalline and conducting acid doped polyaniline films by level surface assisted solution casting approach

    Energy Technology Data Exchange (ETDEWEB)

    Puthirath, Anand B.; Varma, Sreekanth J.; Jayalekshmi, S., E-mail: jayalekshmi@cusat.ac.in [Division for Research in Advanced Materials, Department of Physics, Cochin University of Science and Technology, Cochin, Kerala 682022 (India); Methattel Raman, Shijeesh [Nanophotonic and Optoelectronic Devices Laboratory, Department of Physics, Cochin University of Science and Technology, Cochin, Kerala 682022 (India)

    2016-04-18

    Emeraldine salt form of polyaniline (PANI) was synthesized by chemical oxidative polymerisation method using ammonium persulfate as oxidant. Resultant emeraldine salt form of PANI was dedoped using ammonia solution and then re-doped with camphor sulphonic acid (CSA), naphthaline sulphonic acid (NSA), hydrochloric acid (HCl), and m-cresol. Thin films of these doped PANI samples were deposited on glass substrates using solution casting method with m-cresol as solvent. A level surface was employed to get homogeneous thin films of uniform thickness. Detailed X-ray diffraction studies have shown that the films are exceptionally crystalline. The crystalline peaks observed in the XRD spectra can be indexed to simple monoclinic structure. FTIR and Raman spectroscopy studies provide convincing explanation for the exceptional crystallinity observed in these polymer films. FESEM and AFM images give better details of surface morphology of doped PANI films. The DC electrical conductivity of the samples was measured using four point probe technique. It is seen that the samples also exhibit quite high DC electrical conductivity, about 287 S/cm for CSA doped PANI, 67 S/cm for NSA doped PANI 65 S/cm for HCl doped PANI, and just below 1 S/cm for m-cresol doped PANI. Effect of using the level surface for solution casting is studied and correlated with the observed crystallinity.

  7. Microculture model studies on the effect of sorbic acid on Penicillium chrysogenum, Cladosporium cladosporioides and Ulocladium atrum at different pH levels.

    Science.gov (United States)

    Skirdal, I M; Eklund, T

    1993-02-01

    The minimum growth-inhibitory concentration of sorbic acid has been determined for Penicillium chrysogenum, Cladosporium cladosporioides and Ulocladium atrum at pH 4.1-7.6 by using a microculture technique. This technique had earlier been applied to bacteria and Candida albicans and gave very reliable minimum inhibitory values. This investigation has shown that it is suitable also for determination of mould growth. The minimum inhibitory concentrations of sorbic acid were at the tested pH levels 1-230 mmol l-1 for P. chrysogenum, 0.3-18.0 mmol l-1 for C. cladosporioides and 0.2-33.0 mmol l-1 for U. atrum. A mathematical model for combined inhibition by dissociated and undissociated acid, which gave a good description of the minimum inhibitory concentration data earlier obtained for bacteria and Candida albicans, was suitable also for moulds. Both dissociated and undissociated acid contributed to growth inhibition.

  8. Stochastic level-set variational implicit-solvent approach to solute-solvent interfacial fluctuations

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Shenggao, E-mail: sgzhou@suda.edu.cn, E-mail: bli@math.ucsd.edu [Department of Mathematics and Mathematical Center for Interdiscipline Research, Soochow University, 1 Shizi Street, Jiangsu, Suzhou 215006 (China); Sun, Hui; Cheng, Li-Tien [Department of Mathematics, University of California, San Diego, La Jolla, California 92093-0112 (United States); Dzubiella, Joachim [Soft Matter and Functional Materials, Helmholtz-Zentrum Berlin, 14109 Berlin, Germany and Institut für Physik, Humboldt-Universität zu Berlin, 12489 Berlin (Germany); Li, Bo, E-mail: sgzhou@suda.edu.cn, E-mail: bli@math.ucsd.edu [Department of Mathematics and Quantitative Biology Graduate Program, University of California, San Diego, La Jolla, California 92093-0112 (United States); McCammon, J. Andrew [Department of Chemistry and Biochemistry, Department of Pharmacology, Howard Hughes Medical Institute, University of California, San Diego, La Jolla, California 92093-0365 (United States)

    2016-08-07

    Recent years have seen the initial success of a variational implicit-solvent model (VISM), implemented with a robust level-set method, in capturing efficiently different hydration states and providing quantitatively good estimation of solvation free energies of biomolecules. The level-set minimization of the VISM solvation free-energy functional of all possible solute-solvent interfaces or dielectric boundaries predicts an equilibrium biomolecular conformation that is often close to an initial guess. In this work, we develop a theory in the form of Langevin geometrical flow to incorporate solute-solvent interfacial fluctuations into the VISM. Such fluctuations are crucial to biomolecular conformational changes and binding process. We also develop a stochastic level-set method to numerically implement such a theory. We describe the interfacial fluctuation through the “normal velocity” that is the solute-solvent interfacial force, derive the corresponding stochastic level-set equation in the sense of Stratonovich so that the surface representation is independent of the choice of implicit function, and develop numerical techniques for solving such an equation and processing the numerical data. We apply our computational method to study the dewetting transition in the system of two hydrophobic plates and a hydrophobic cavity of a synthetic host molecule cucurbit[7]uril. Numerical simulations demonstrate that our approach can describe an underlying system jumping out of a local minimum of the free-energy functional and can capture dewetting transitions of hydrophobic systems. In the case of two hydrophobic plates, we find that the wavelength of interfacial fluctuations has a strong influence to the dewetting transition. In addition, we find that the estimated energy barrier of the dewetting transition scales quadratically with the inter-plate distance, agreeing well with existing studies of molecular dynamics simulations. Our work is a first step toward the

  9. An All-Solid-State pH Sensor Employing Fluorine-Terminated Polycrystalline Boron-Doped Diamond as a pH-Insensitive Solution-Gate Field-Effect Transistor.

    Science.gov (United States)

    Shintani, Yukihiro; Kobayashi, Mikinori; Kawarada, Hiroshi

    2017-05-05

    A fluorine-terminated polycrystalline boron-doped diamond surface is successfully employed as a pH-insensitive SGFET (solution-gate field-effect transistor) for an all-solid-state pH sensor. The fluorinated polycrystalline boron-doped diamond (BDD) channel possesses a pH-insensitivity of less than 3mV/pH compared with a pH-sensitive oxygenated channel. With differential FET (field-effect transistor) sensing, a sensitivity of 27 mv/pH was obtained in the pH range of 2-10; therefore, it demonstrated excellent performance for an all-solid-state pH sensor with a pH-sensitive oxygen-terminated polycrystalline BDD SGFET and a platinum quasi-reference electrode, respectively.

  10. Two-Level Solutions to Exponentially Complex Problems in Glass Science

    DEFF Research Database (Denmark)

    Mauro, John C.; Smedskjær, Morten Mattrup

    Glass poses an especially challenging problem for physicists. The key to making progress in theoretical glass science is to extract the key physics governing properties of practical interest. In this spirit, we discuss several two-level solutions to exponentially complex problems in glass science....... Topological constraint theory, originally developed by J.C. Phillips, is based on a two-level description of rigid and floppy modes in a glass network and can be used to derive quantitatively accurate and analytically solvable models for a variety of macroscopic properties. The temperature dependence...... that captures both primary and secondary relaxation modes. Such a model also offers the ability to calculate the distinguishability of particles during glass transition and relaxation processes. Two-level models can also be used to capture the distribution of various network-forming species in mixed...

  11. Solutes transport characteristics in peritoneal dialysis: variations in glucose and insulin serum levels.

    Science.gov (United States)

    da Silva, Dirceu R; Figueiredo, Ana E; Antonello, Ivan C; Poli de Figueiredo, Carlos E; d'Avila, Domingos O

    2008-01-01

    Differences in small solutes transport rate (SSTR) during peritoneal dialysis (PD) may affect water and solutes removal. Patients with high SSTR must rely on shorter dwell times and increased dialysate glucose concentrations to keep fluid balance. Glucose absorption during peritoneal dialysis (PD), besides affecting glucose and insulin metabolism, may induce weight gain. The study aimed at examining acute glucose and insulin serum level changes and other potential relationships in PD patients with diverse SSTR. This cross-sectional study used a modified peritoneal equilibration test (PET) that enrolled 34 prevalent PD patients. Zero, 15, 30, 60, 120, 180, and 240-minute glucose and insulin serum levels were measured. Insulin resistance index was assessed by the homeostasis model assessment (HOMA-IR) formula. SSTR categories were classified by quartiles of the four-hour dialysate/serum creatinine ratio (D(4)/P(Cr)). Demographic and clinical variables were evaluated, and the body mass index (BMI) was estimated. Correlations among variables of interest and categories of SSTR were explored. Glucose serum levels were significantly different at 15, 30, and 60 minutes between high and low SSTR categories (p = 0.014, 0.009, and 0.022). Increased BMI (25.5 +/- 5.1) and insulin resistance [HOMA-IR = 2.60 (1.40-4.23)] were evidenced overall. Very strong to moderate correlations between insulin levels along the PET and HOMA-IR (r = 0.973, 0.834, 0.766, 0.728, 0.843, 0.857, 0.882) and BMI (r = 0.562, 0.459, 0.417, 0.370, 0.508, 0.514, 0.483) were disclosed. CONCLUSIONS; Early glucose serum levels were associated with SSTR during a PET. Overweight or obesity and insulin resistance were prevalent. An association between insulin serum levels and BMI was demonstrated.

  12. Numerical modeling of acidity distribution in antroduodenum aimed at identifying anomalous zones at consuming drinks with different pH level

    Directory of Open Access Journals (Sweden)

    M.R. Kamaltdinov

    2017-03-01

    Full Text Available The article focuses on describing mathematical model of a multi-phase flow in antroduodenum and its application for predicting digestive process features, including pH level detection. The suggested sub-model representing antroduodenal area of gastrointestinal tract is being developed within the frameworks of mathematical multilevel model depicting evolution of damage to critical organs and systems under exposure to risk factors. We introduced damages as per three functions (motor, secretory and absorbing one to several gastrointestinal tract zones (body of stomach, antrum, and duodenum and to pancreas and liver, into the sub-model. Mathematical problem statement includes records of mass and impulse conservation equations for mixture of liquid incompressible phases; ratios for mass flow intensity vector due to diffusion processes; ratios for mass sources due to reactions, secretion and components absorption, food dissolution, initial and terminal conditions. We obtained numeric experiment results when drinks with various pH level (2.3; 3.5; 7 were consumed; they revealed that anomalous considerable increase in acidity occurred in pyloric opening zone and duodenal cap zone when a drink with pH level equal to 2.3 was consumed. The results presented in this work make a considerable contribution into mathematical modeling development used to describe multiphase flows in biological channels with variable form. We showed that obtained acidity levels in various antroduodenum zones correspond to experimental data given in the works of other researchers. In future the model can be applied to predict risks of duodenum damages evolvement together with detecting areas of their localization under exposure to negative factors.

  13. Variation in bull beef quality due to ultimate muscle pH is correlated to endopeptidase and small heat shock protein levels.

    Science.gov (United States)

    Pulford, D J; Dobbie, P; Fraga Vazquez, S; Fraser-Smith, E; Frost, D A; Morris, C A

    2009-09-01

    This study set out to determine if ultimate pH (pH(u)) affected the performance of intracellular small heat shock protein and endopeptidase dynamics in muscle during beef ageing. Longissimus dorsi muscles from 39 Angus or Limousin×Angus bulls were examined to see if pH(u) achieved at 22h post mortem (rigor) affected tenderness and water holding capacity of beef. Samples were segregated into three pH(u) groups termed high (pH>6.3), intermediate (5.7pHpHpH(u) beef. More than 30% of bull beef did not achieve acceptable tenderness at 8 days post mortem with this ageing regime. No significant differences in calpain or cathepsin enzyme levels due to meat pH were observed until after 22h post mortem, but low pH(u) beef had elevated caspase 3/7 activity soon after slaughter. At 22h post mortem, greater levels of μ-calpain enzyme were found in the high and intermediate pH(u) beef and cathepsin B levels were superior in the low pH(u) beef after 2 days post mortem. Different rates of desmin and troponin T protein degradation were also observed in aged bull beef. Both proteins were degraded within 6h post mortem for high pH(u) beef, but took >3 days post mortem for intermediate pH(u) beef. High levels of alpha β-crystallin (aβC) at 22h post mortem coincided with delayed muscle protein degradation for low pH(u) beef. Our results support the hypothesis that aβC shields myofibrils and buffers against endopeptidase degradation of beef structure during ageing.

  14. Direct spectrophotometric analysis of low level Pu (III) in Pu(IV) nitrate solution

    International Nuclear Information System (INIS)

    Mageswaran, P.; Suresh Kumar, K.; Kumar, T.; Gayen, J.K.; Shreekumar, B.; Dey, P.K.

    2010-01-01

    Among the various methods demonstrated for the conversion of plutonium nitrate to its oxide, the oxalate precipitation process either as Pu (III) or Pu (IV) oxalate gained wide acceptance. Since uranous nitrate is the most successful partitioning agent used in the PUREX process for the separation of Pu from the bulk amount of U, the Pu (III) oxalate precipitation of the purified nitrate solution will not give required decontamination from U. Hence Pu IV oxalate precipitation process is a better option to achieve the end user's specified PuO 2 product. Prior to the precipitation process, ensuring of the Pu (IV) oxidation state is essential. Hence monitoring of the level of Pu oxidation state either Pu (III) or Pu (IV) in the feed solution plays a significant role to establish complete conversion of Pu (III). The method in vogue to estimate Pu(lV) content is extractive radiometry using Theonyl Trifluoro Acetone (TTA). As the the method warrants a sample preparation with respect to acidity, a precise measurement of Pu (IV) without affecting the Pu(III) level in the feed sample is difficult. Present study is focused on the exploration of direct spectrophotometry using an optic fiber probe of path length of 40mm to monitor the low level of Pu(III) after removing the bulk Pu(lV) which interfere in the Pu(III) absorption spectrum, using TTA-TBP synergistic mixture without changing the sample acidity

  15. A plant oil-containing pH 4 emulsion improves epidermal barrier structure and enhances ceramide levels in aged skin.

    Science.gov (United States)

    Blaak, J; Dähnhardt, D; Dähnhardt-Pfeiffer, S; Bielfeldt, S; Wilhelm, K-P; Wohlfart, R; Staib, P

    2017-06-01

    Xerosis is a serious problem among the very old. It is a dermatological challenge caused by significant alterations in stratum corneum (SC) function and structure. Two negative changes in aged skin are (i) the enhanced skin surface pH and (ii) the altered SC lipid content, composition and ordering. Therefore, we investigated the way in which an acidic skin care product with different plant oils affects SC function, structure and lipid profile in older subjects with dry skin. Before and after a 3-week application period, different biophysical measurements were performed: transepidermal water loss, SC hydration and skin surface pH. In addition, the SC lipid matrix was evaluated by analysis of the intercellular lipid lamellae and the SC lipid profile. After treatment, a significant increase in lipid lamellae in the intercellular space of the SC was observed in the area treated with the test product compared to the untreated area. Furthermore, the ceramide level was found to be increased, although ceramides were not provided by the acidic test formulation. In summary, topical application of a pH 4.0 product containing plant oils improves epidermal barrier formation and SC lipid ordering and ratio in aged dry skin. © 2016 Society of Cosmetic Scientists and the Société Française de Cosmétologie.

  16. Sustaining elevated levels of nitrite in the oral cavity through consumption of nitrate-rich beetroot juice in young healthy adults reduces salivary pH.

    Science.gov (United States)

    Hohensinn, Barbara; Haselgrübler, Renate; Müller, Ulrike; Stadlbauer, Verena; Lanzerstorfer, Peter; Lirk, Gerald; Höglinger, Otmar; Weghuber, Julian

    2016-11-30

    Dietary inorganic nitrate (NO 3 - ) and its reduced forms nitrite (NO 2 - ) and nitric oxide (NO), respectively, are of critical importance for host defense in the oral cavity. High concentrations of salivary nitrate are linked to a lower prevalence of caries due to growth inhibition of cariogenic bacteria. In-vitro studies suggest that the formation of antimicrobial NO results in an increase of the pH preventing erosion of tooth enamel. The purpose of this study was to prove this effect in-vivo. In a randomized clinical study with 46 subjects we investigated whether NO 3 - rich beetroot juice exhibits a protective effect against caries by an increase of salivary pH. Our results show that, in comparison to a placebo group, consumption of beetroot juice that contains 4000 mg/L NO 3 - results in elevated levels of salivary NO 2 - , nitrite NO 3 - , and NO. Furthermore, we determined an increase of the mean pH of saliva from 7.0 to 7.5, confirming the anti-cariogenic effect of the used NO 3 - -rich beetroot juice. Taken together, we have found that NO 3 - -rich beetroot juice holds potential effects against dental caries by preventing acidification of human saliva. C-87-15 (Ethics Commissions of Upper Austria). Copyright © 2016 The Authors. Published by Elsevier Inc. All rights reserved.

  17. A policy hackathon for analysing impacts and solutions up to 20 metres sea-level rise

    Science.gov (United States)

    Haasnoot, Marjolijn; Bouwer, Laurens; Kwadijk, Jaap

    2017-04-01

    We organised a policy hackathon in order to quantify the impacts accelerated and high-end sea-level rise up to 20 metres on the coast of the Netherlands, and develop possible solutions. This was done during one day, with 20 experts that had a wide variety of disciplines, including hydrology, geology, coastal engineering, economics, and public policy. During the process the problem was divided up into several sub-sets of issues that were analysed and solved within small teams of between 4 to 8 people. Both a top-down impact analysis and bottom-up vulnerability analysis was done by answering the questions: What is the impact of sea level rise of x meter?; and How much sea level rise can be accommodated with before transformative actions are needed? Next, adaptation tipping points were identified that describe conditions under which the coastal system starts to perform unacceptably. Reasons for an adaptation tipping point can be technical (technically not possible), economic (cost-benefits are negative), or resources (available space, sand, energy production, financial). The results are presented in a summary document, and through an infographic displaying different adaptation tipping points and milestones that occur when the sea level rises up to 20 m. No technical limitations were found for adaptation, but many important decisions need to be taken. Although accelerated sea level rise seems far away it can have important consequences for short-term decisions that are required for transformative actions. Such extensive actions require more time for implementation. Also, other action may become ineffective before their design life. This hackathon exercise shows that it is possible to map within a short time frame the issues at hand, as well as potentially effective solutions. This can be replicated for other problems, and can be useful for several decision-makers that require quick but in-depth analysis of their long-term planning problems.

  18. Determination of optimum levels of nitrogen, phosphorus and potassium of oil palm seedlings in solution culture

    Directory of Open Access Journals (Sweden)

    Hasmah Mohidin

    2015-09-01

    Full Text Available Balanced nutrient elements in fertilizer play a critical role in oil palm seedling successful growth and development, and at the same time reduces of fertilizer losses in the environment. This study examines the effect of different levels of N, P2O5 and K2O for oil palm seedlings in solution culture on growth traits, nutrient uptake in plant tissues and biomass accumulation under nursery conditions. Five concentration levels of N (50, 100, 300, 600 and 900 mg L–1, P2O5 and K2O (15, 30, 60, 90 and 120 mg L–1 were used in a completely randomized design (CRD with five replications for each. Parameters measured during the growing period include - plant height, leaf number/plant, stem diameter, SPAD chlorophyll value, and at harvest – total leaf area, root dry weight, shoot dry weight and total dry weight. Different levels of N, P2O5 and K2O showed significant effects on all the parameters studied. The highest values for diameter, plant height, leaf number/plant, total leaf area, root dry weight, shoot dry weight and total dry biomass were obtained using 100, 90 and 300 mg/L levels of N, P2O5 and K2O, respectively. Most of the growth parameters, declined with lower levels of N, P2O5 and K2O. The results of this study provide a new knowledge to produce oil palm plant with better nutrient management at the nursery under solution culture.

  19. Determination of optimum levels of nitrogen, phosphorus and potassium of oil palm seedlings in solution culture

    Directory of Open Access Journals (Sweden)

    Hasmah Mohidin

    2015-01-01

    Full Text Available Balanced nutrient elements in fertilizer play a critical role in oil palm seedling successful growth and development, and at the same time reduces of fertilizer losses in the environment. This study examines the effect of different levels of N, P2O5 and K2O for oil palm seedlings in solution culture on growth traits, nutrient uptake in plant tissues and biomass accumulation under nursery conditions. Five concentration levels of N (50, 100, 300, 600 and 900 mg L–1, P2O5 and K2O (15, 30, 60, 90 and 120 mg L–1 were used in a completely randomized design (CRD with five replications for each. Parameters measured during the growing period include - plant height, leaf number/plant, stem diameter, SPAD chlorophyll value, and at harvest – total leaf area, root dry weight, shoot dry weight and total dry weight. Different levels of N, P2O5 and K2O showed significant effects on all the parameters studied. The highest values for diameter, plant height, leaf number/plant, total leaf area, root dry weight, shoot dry weight and total dry biomass were obtained using 100, 90 and 300 mg/L levels of N, P2O5 and K2O, respectively. Most of the growth parameters, declined with lower levels of N, P2O5 and K2O. The results of this study provide a new knowledge to produce oil palm plant with better nutrient management at the nursery under solution culture.

  20. The next generation in optical transport semiconductors: IC solutions at the system level

    Science.gov (United States)

    Gomatam, Badri N.

    2005-02-01

    In this tutorial overview, we survey some of the challenging problems facing Optical Transport and their solutions using new semiconductor-based technologies. Advances in 0.13um CMOS, SiGe/HBT and InP/HBT IC process technologies and mixed-signal design strategies are the fundamental breakthroughs that have made these solutions possible. In combination with innovative packaging and transponder/transceiver architectures IC approaches have clearly demonstrated enhanced optical link budgets with simultaneously lower (perhaps the lowest to date) cost and manufacturability tradeoffs. This paper will describe: *Electronic Dispersion Compensation broadly viewed as the overcoming of dispersion based limits to OC-192 links and extending link budgets, *Error Control/Coding also known as Forward Error Correction (FEC), *Adaptive Receivers for signal quality monitoring for real-time estimation of Q/OSNR, eye-pattern, signal BER and related temporal statistics (such as jitter). We will discuss the theoretical underpinnings of these receiver and transmitter architectures, provide examples of system performance and conclude with general market trends. These Physical layer IC solutions represent a fundamental new toolbox of options for equipment designers in addressing systems level problems. With unmatched cost and yield/performance tradeoffs, it is expected that IC approaches will provide significant flexibility in turn, for carriers and service providers who must ultimately manage the network and assure acceptable quality of service under stringent cost constraints.

  1. Gas exchange and organic solutes in forage sorghum genotypes grown under different salinity levels

    Directory of Open Access Journals (Sweden)

    Daniela S. Coelho

    Full Text Available ABSTRACT Adaptation of plants to saline environments depends on the activation of mechanisms that minimize the effects of excess ions on vital processes, such as photosynthesis. The objective of this study was to evaluate the leaf gas exchange, chlorophyll, and organic solute in ten genotypes of forage sorghum irrigated with solutions of different salinity levels. The experiment was conducted in a randomized block design, in a 10 x 6 factorial arrangement, with three replications, using ten genotypes - F305, BRS-655, BRS-610, Volumax, 1.015.045, 1.016.005, 1.016.009, 1.016.013, 1.016.015 and 1.016.031 - and six saline solutions, with electrical conductivity (ECw of 0, 2.5, 5.0, 7.5, 10 and 12.5 dS m-1. The photosynthetic activity in forage sorghum plants reduces with increasing salinity, and this response was found in the ten genotypes evaluated. The chlorophyll and protein contents were not affected by salinity, whereas carbohydrates and amino acid contents increased with increasing ECw. Soluble sugars are essential for osmoregulation of forage sorghum due to its high content in leaves.

  2. Faecal urobilinogen levels and pH of stools in population groups with different incidence of cancer of the colon, and their possible role in its aetiology.

    OpenAIRE

    Malhotra, S L

    1982-01-01

    Mean faecal urobilinogen levels and the pH of stools were both found to be higher in subjects from a population group at high risk of developing cancer of the colon than in subjects matched for age, sex and socioeconomic status from a low-risk population group. An alkaline reaction of the colon contents seems to have a tumorigenic effect by a direct action on the mucus of the mucous cells. An acidic reaction, on the other hand, appears to be protective. These differences are dependent on the ...

  3. The Effect of ringer Lactate as the Priming Solution of the Cardiopulmonary by Pass Circuit on Plasma Potassium Levels after Open Heart Surgery in Children

    Directory of Open Access Journals (Sweden)

    Arash Peivandi Yazdi

    2015-11-01

    Full Text Available Background: Conduct of cardiopulmonary bypass (CPB due to the higher volume of priming solution in comparison to the total blood volume in children requires careful consideration. Recently attention has been focused on the potential risk of hyperkalemia in these patients. Given its significant effects on cardiac rhythm, hyperkalemia is considered a medical emergency. In this cross-sectional study we aimed to determine the changes in K+ and other electrolytes following CPB in a pediatric cardiac surgery setting. Method: Sixty children scheduled for pediatric cardiac surgery weighing more than 5 kilograms with Hct level above 30% were enrolled. The prime solution used was Ringer-lactate. Venous blood were collected at defined time points: before, during and after CPB and at discharge. A p-value of less than 0.05 was considered statistically significant. Results: Mean age of the studied patients was 3.69±2.77 years. A rise in potassium levels during surgery was recorded. Also a significant difference in the potassium levels before surgery and at discharge were observed (p=0.007. A significant drop and a subsequent rise in the Hct level was seen overtime whereas a significant decrease in the PH and bicarbonate levels were detected. 31 experienced cardiac arrhythmia after undergoing CPB. Conclusion: A K+-free crystalloid that will offset the K+ load of stored blood is highly anticipated in these patients

  4. Solution Algorithm for a New Bi-Level Discrete Network Design Problem

    Directory of Open Access Journals (Sweden)

    Qun Chen

    2013-12-01

    Full Text Available A new discrete network design problem (DNDP was pro-posed in this paper, where the variables can be a series of integers rather than just 0-1. The new DNDP can determine both capacity improvement grades of reconstruction roads and locations and capacity grades of newly added roads, and thus complies with the practical projects where road capacity can only be some discrete levels corresponding to the number of lanes of roads. This paper designed a solution algorithm combining branch-and-bound with Hooke-Jeeves algorithm, where feasible integer solutions are recorded in searching the process of Hooke-Jeeves algorithm, lend -ing itself to determine the upper bound of the upper-level problem. The thresholds for branch cutting and ending were set for earlier convergence. Numerical examples are given to demonstrate the efficiency of the proposed algorithm.

  5. EGSIEM combination service: combination of GRACE monthly K-band solutions on normal equation level

    Science.gov (United States)

    Meyer, Ulrich; Jean, Yoomin; Arnold, Daniel; Jäggi, Adrian

    2017-04-01

    The European Gravity Service for Improved Emergency Management (EGSIEM) project offers a scientific combination service, combining for the first time monthly GRACE gravity fields of different analysis centers (ACs) on normal equation (NEQ) level and thus taking all correlations between the gravity field coefficients and pre-eliminated orbit and instrument parameters correctly into account. Optimal weights for the individual NEQs are commonly derived by variance component estimation (VCE), as is the case for the products of the International VLBI Service (IVS) or the DTRF2008 reference frame realisation that are also derived by combination on NEQ-level. But variance factors are based on post-fit residuals and strongly depend on observation sampling and noise modeling, which both are very diverse in case of the individual EGSIEM ACs. These variance factors do not necessarily represent the true error levels of the estimated gravity field parameters that are still governed by analysis noise. We present a combination approach where weights are derived on solution level, thereby taking the analysis noise into account.

  6. Food safety and ecologization: practical solutions to problems at the regional level in current economic conditions

    Directory of Open Access Journals (Sweden)

    Lysochenko Alla, A.

    2015-03-01

    Full Text Available Ensuring food security and greening both at the level of the country, and at the level of regions are main objectives of modern agroeconomic policy. The state support creates favorable conditions for dynamic development of agrarian and industrial complex, raises investment opportunities and competitiveness of agricultural producers. A realization of the actions directed on assistance to the enterprises making import-substituting production of the regional agro-industrial complex is actual in modern economic conditions. The solution of this problem consists of investment projects implementation and production expansion of the operating enterprises. Considering new economic conditions, the ensuring financial stability of agricultural producers, availability of the food to needy segments of the population, production of valeologically safe food, and also increase efficiency of use of natural resources and conditions along with preservation of quality of environment at the local, regional and global levels are particularly acute challenges. State regulation of development of an agrofood complex of Russia remains a necessary condition for its reproduction functioning, and the social and economic policy has to provide economic availability of the food to all groups of the population that causes need of standard and legal fixing of mechanisms offood security achievement at the regional level.

  7. An integrated radar model solution for mission level performance and cost trades

    Science.gov (United States)

    Hodge, John; Duncan, Kerron; Zimmerman, Madeline; Drupp, Rob; Manno, Mike; Barrett, Donald; Smith, Amelia

    2017-05-01

    A fully integrated Mission-Level Radar model is in development as part of a multi-year effort under the Northrop Grumman Mission Systems (NGMS) sector's Model Based Engineering (MBE) initiative to digitally interconnect and unify previously separate performance and cost models. In 2016, an NGMS internal research and development (IR and D) funded multidisciplinary team integrated radio frequency (RF), power, control, size, weight, thermal, and cost models together using a commercial-off-the-shelf software, ModelCenter, for an Active Electronically Scanned Array (AESA) radar system. Each represented model was digitally connected with standard interfaces and unified to allow end-to-end mission system optimization and trade studies. The radar model was then linked to the Air Force's own mission modeling framework (AFSIM). The team first had to identify the necessary models, and with the aid of subject matter experts (SMEs) understand and document the inputs, outputs, and behaviors of the component models. This agile development process and collaboration enabled rapid integration of disparate models and the validation of their combined system performance. This MBE framework will allow NGMS to design systems more efficiently and affordably, optimize architectures, and provide increased value to the customer. The model integrates detailed component models that validate cost and performance at the physics level with high-level models that provide visualization of a platform mission. This connectivity of component to mission models allows hardware and software design solutions to be better optimized to meet mission needs, creating cost-optimal solutions for the customer, while reducing design cycle time through risk mitigation and early validation of design decisions.

  8. Influence of pH, temperature, and concentration on stabilization of aqueous hornet silk solution and fabrication of salt-free materials.

    Science.gov (United States)

    Kameda, Tsunenori

    2015-01-01

    We found that an aqueous solution of silk from cocoons produced by hornet larvae (hornet silk) can be obtained when the solution is adjusted to basic conditions of pH > 9.2. It is known that native hornet cocoons can be dissolved in concentrated aqueous solution of salts, such as lithium bromide (LiBr) and calcium chloride (CaCl2). Upon the removal of these salts from solution by dialysis, solidification, gelation, or sedimentation of hornet silk is known to occur. In the present study, under basic conditions, however, no such solidification occurred, even after salt removal. In this study, ammonia was used for alkalization of solution because it is volatilized during the casting process and pure hornet silk materials can be obtained after drying. The effects of the concentrations of hornet silk and ammonia, as well as dialysis temperature, on preventing gelation during dialysis were investigated. Dialysis conditions that limit the degradation of hornet silk by hydrolysis in alkali solution were identified. Moreover, casting conditions to prepare flexible and transparent hornet silk film from aqueous ammonia solution were optimized. Molecular structural analysis of hornet silk in aqueous ammonia solution and cast film indicated the formation of α-helix conformations. © 2014 Wiley Periodicals, Inc.

  9. Modelling of the effect of solute structure and mobile phase pH and composition on the retention of phenoxy acid herbicides in reversed-phase high-performance liquid chromatography

    International Nuclear Information System (INIS)

    Aschi, Massimiliano; D'Archivio, Angelo Antonio; Mazzeo, Pietro; Pierabella, Mirko; Ruggieri, Fabrizio

    2008-01-01

    A feed-forward artificial neural network (ANN) learned by error back-propagation is used to generate a retention predictive model for phenoxy acid herbicides in isocratic reversed-phase high-performance liquid chromatography. The investigated solutes (18 compounds), apart from the most common herbicides of this class, include some derivatives of benzoic acid and phenylacetic acid structurally related to phenoxy acids, as a whole covering a pK a range between 2.3 and 4.3. A mixed model in terms of both solute descriptors and eluent attributes is built with the aim of predicting retention in water-acetonitrile mobile phases within a large range of composition (acetonitrile from 30% to 70%, v/v) and acidity (pH of water before mixing with acetonitrile ranging between 2 and 5). The set of input variables consists of solute pK a and quantum chemical molecular descriptors of both the neutral and dissociated form, %v/v of acetonitrile in the mobile phase and pH of aqueous phase before mixing with acetonitrile. After elimination of redundant variables, a nine-dimensional model is identified and its prediction ability is evaluated by external validation based on three solutes not involved in model generation and by cross-validation. A multilinear counterpart in terms of the same descriptors is seen to provide a noticeably poorer retention prediction

  10. Modelling of the effect of solute structure and mobile phase pH and composition on the retention of phenoxy acid herbicides in reversed-phase high-performance liquid chromatography

    Energy Technology Data Exchange (ETDEWEB)

    Aschi, Massimiliano [Dipartimento di Chimica, Ingegneria Chimica e Materiali, Universita degli Studi di L' Aquila, Via Vetoio, 67010 Coppito, L' Aquila (Italy); D' Archivio, Angelo Antonio [Dipartimento di Chimica, Ingegneria Chimica e Materiali, Universita degli Studi di L' Aquila, Via Vetoio, 67010 Coppito, L' Aquila (Italy)], E-mail: darchivi@univaq.it; Mazzeo, Pietro; Pierabella, Mirko; Ruggieri, Fabrizio [Dipartimento di Chimica, Ingegneria Chimica e Materiali, Universita degli Studi di L' Aquila, Via Vetoio, 67010 Coppito, L' Aquila (Italy)

    2008-06-02

    A feed-forward artificial neural network (ANN) learned by error back-propagation is used to generate a retention predictive model for phenoxy acid herbicides in isocratic reversed-phase high-performance liquid chromatography. The investigated solutes (18 compounds), apart from the most common herbicides of this class, include some derivatives of benzoic acid and phenylacetic acid structurally related to phenoxy acids, as a whole covering a pK{sub a} range between 2.3 and 4.3. A mixed model in terms of both solute descriptors and eluent attributes is built with the aim of predicting retention in water-acetonitrile mobile phases within a large range of composition (acetonitrile from 30% to 70%, v/v) and acidity (pH of water before mixing with acetonitrile ranging between 2 and 5). The set of input variables consists of solute pK{sub a} and quantum chemical molecular descriptors of both the neutral and dissociated form, %v/v of acetonitrile in the mobile phase and pH of aqueous phase before mixing with acetonitrile. After elimination of redundant variables, a nine-dimensional model is identified and its prediction ability is evaluated by external validation based on three solutes not involved in model generation and by cross-validation. A multilinear counterpart in terms of the same descriptors is seen to provide a noticeably poorer retention prediction.

  11. Cinética do escurecimeno não-enzimático com soluções modelo de açúcares e aminoácidos em pH neutro e ácido = Kinetic of non-enzimatic browning with model solutions of sugar and aminoacids in neutral and acid pH

    Directory of Open Access Journals (Sweden)

    Vandré Barbosa Brião

    2011-01-01

    Full Text Available A cor dos alimentos é um importante atributo para a escolha do consumidor. O escurecimento é desejável em alguns alimentos pela cor e pelo aroma produzidos (como nos casos do pão e carne assada, mas, é indesejável em outros (como no tratamento térmico de leite. A reação de Maillard é influenciada pela natureza dos açúcares e aminoácidos envolvidos, bem como pelo pH e temperatura do processo. O objetivo do trabalho foi avaliar o escurecimento de soluções modelo contendo açúcares e aminoácidos pela reação de Maillard em pH neutro e ácido, obtendo as taxas de reação e avaliando a cinética dela. Doistipos de açúcares (glicose e lactose foram misturados com dois tipos de aminoácidos (glicina ou glutamato de sódio em pH 7,0 e pH 5,1. As soluções (2 mol L-1 foram aquecidas em água fervente (97ºC, e a absorbância medida (420 nm em intervalos de tempo. A glicose apresentou maior taxa de reação que a lactose, enquanto que entre os aminoácidos a glicina reagiu com intensidade semelhante ao glutamato. A redução do pH do meio retarda a reação, e o escurecimento demonstrou menor taxa de reação em pH ácido.The color of food is an important attribute for consumer choice. Browning is desirable in some foods due to the color and flavor itproduces (such as in bread and roasted meat, but is undesirable for others (such as heattreated milk. The Maillard reaction is influenced by the nature of the sugars and amino acids involved, as well as the pH and temperature of the process. The aim of this work was to evaluate the browning of model solutions containing sugars and amino acids due to the Maillard reaction in neutral and acid pH, and to calculate the reaction rate and the kinetics of the reaction. Two types of sugars (glucose or lactose were mixed with amino acids(glycine or sodium glutamate in pH 7.0 or pH 5.1. The solutions (2 mol L-1 were heated in boiling water (97ºC, and the absorbance was measured (420 nm at time

  12. Redox levels in aqueous solution: Effect of van der Waals interactions and hybrid functionals

    Energy Technology Data Exchange (ETDEWEB)

    Ambrosio, Francesco, E-mail: Francesco.Ambrosio@epfl.ch; Miceli, Giacomo; Pasquarello, Alfredo [Chaire de Simulation à l’Echelle Atomique (CSEA), Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne (Switzerland)

    2015-12-28

    We investigate redox levels in aqueous solution using a combination of ab initio molecular dynamics (MD) simulations and thermodynamic integration methods. The molecular dynamics are performed with both the semilocal Perdew-Burke-Ernzerhof functional and a nonlocal functional (rVV10) accounting for van der Waals (vdW) interactions. The band edges are determined through three different schemes, namely, from the energy of the highest occupied and of the lowest unoccupied Kohn-Sham states, from total-energy differences, and from a linear extrapolation of the density of states. It is shown that the latter does not depend on the system size while the former two are subject to significant finite-size effects. For the redox levels, we provide a formulation in analogy to the definition of charge transition levels for defects in crystalline materials. We consider the H{sup +}/H{sub 2} level defining the standard hydrogen electrode, the OH{sup −}/OH{sup ∗} level corresponding to the oxidation of the hydroxyl ion, and the H{sub 2}O/OH{sup ∗} level for the dehydrogenation of water. In spite of the large structural modifications induced in liquid water, vdW interactions do not lead to any significant structural effect on the calculated band gap and band edges. The effect on the redox levels is also small since the solvation properties of ionic species are little affected by vdW interactions. Since the electronic properties are not significantly affected by the underlying structural properties, it is justified to perform hybrid functional calculations on the configurations of our MD simulations. The redox levels calculated as a function of the fraction α of Fock exchange are found to remain constant, reproducing a general behavior previously observed for charge transition levels of defects. Comparison with experimental values shows very good agreement. At variance, the band edges and the band gap evolve linearly with α. For α ≃ 0.40, we achieve a band gap, band

  13. Redox levels in aqueous solution: Effect of van der Waals interactions and hybrid functionals

    Science.gov (United States)

    Ambrosio, Francesco; Miceli, Giacomo; Pasquarello, Alfredo

    2015-12-01

    We investigate redox levels in aqueous solution using a combination of ab initio molecular dynamics (MD) simulations and thermodynamic integration methods. The molecular dynamics are performed with both the semilocal Perdew-Burke-Ernzerhof functional and a nonlocal functional (rVV10) accounting for van der Waals (vdW) interactions. The band edges are determined through three different schemes, namely, from the energy of the highest occupied and of the lowest unoccupied Kohn-Sham states, from total-energy differences, and from a linear extrapolation of the density of states. It is shown that the latter does not depend on the system size while the former two are subject to significant finite-size effects. For the redox levels, we provide a formulation in analogy to the definition of charge transition levels for defects in crystalline materials. We consider the H+/H2 level defining the standard hydrogen electrode, the OH-/OH∗ level corresponding to the oxidation of the hydroxyl ion, and the H2O/OH∗ level for the dehydrogenation of water. In spite of the large structural modifications induced in liquid water, vdW interactions do not lead to any significant structural effect on the calculated band gap and band edges. The effect on the redox levels is also small since the solvation properties of ionic species are little affected by vdW interactions. Since the electronic properties are not significantly affected by the underlying structural properties, it is justified to perform hybrid functional calculations on the configurations of our MD simulations. The redox levels calculated as a function of the fraction α of Fock exchange are found to remain constant, reproducing a general behavior previously observed for charge transition levels of defects. Comparison with experimental values shows very good agreement. At variance, the band edges and the band gap evolve linearly with α. For α ≃ 0.40, we achieve a band gap, band-edge positions, and redox levels in overall

  14. Comprehensive solutions to the Bloch equations and dynamical models for open two-level systems

    Science.gov (United States)

    Skinner, Thomas E.

    2018-01-01

    The Bloch equation and its variants constitute the fundamental dynamical model for arbitrary two-level systems. Many important processes, including those in more complicated systems, can be modeled and understood through the two-level approximation. It is therefore of widespread relevance, especially as it relates to understanding dissipative processes in current cutting-edge applications of quantum mechanics. Although the Bloch equation has been the subject of considerable analysis in the 70 years since its inception, there is still, perhaps surprisingly, significant work that can be done. This paper extends the scope of previous analyses. It provides a framework for more fully understanding the dynamics of dissipative two-level systems. A solution is derived that is compact, tractable, and completely general, in contrast to previous results. Any solution of the Bloch equation depends on three roots of a cubic polynomial that are crucial to the time dependence of the system. The roots are typically only sketched out qualitatively, with no indication of their dependence on the physical parameters of the problem. Degenerate roots, which modify the solutions, have been ignored altogether. Here the roots are obtained explicitly in terms of a single real-valued root that is expressed as a simple function of the system parameters. For the conventional Bloch equation, a simple graphical representation of this root is presented that makes evident the explicit time dependence of the system for each point in the parameter space. Several intuitive, visual models of system dynamics are developed. A Euclidean coordinate system is identified in which any generalized Bloch equation is separable, i.e., the sum of commuting rotation and relaxation operators. The time evolution in this frame is simply a rotation followed by relaxation at modified rates that play a role similar to the standard longitudinal and transverse rates. These rates are functions of the applied field, which

  15. The role of pH in heavy metal detoxification by biosorption from ...

    African Journals Online (AJOL)

    The high level of toxic metal pollution in the environment is a result of increased human activities. The hydrogen ion concentration of solutions has been known to affect reactions in solutions. The role of pH in As(V), Pb(II) and Hg(II) ions detoxification by bio-sorption from aqueous solutions using coconut fiber and sawdust ...

  16. Corrosion of carbon steel in saturated high-level waste salt solutions

    International Nuclear Information System (INIS)

    Wiersma, B.J.; Parish, W.R.

    1997-01-01

    High level waste stored as crystallized salts is to be removed from carbon steel tanks by water dissolution. Dissolution of the saltcake must be performed in a manner which will not impact the integrity of the tank. Corrosion testing was performed to determine the amount of corrosion inhibitor that must be added to the dissolution water in order to ensure that the salt solution formed would not induce corrosion degradation of the tank materials. The corrosion testing performed included controlled potential slow strain rate, coupon immersion, and potentiodynamic polarization tests. These tests were utilized to investigate the susceptibility of the cooling coil material to stress corrosion cracking in the anticipated environments. No evidence of SCC was observed in any of the tests. Based on these results, the recommended corrosion requirements were that the temperature of the salt solution be less than 50 degrees C and that the minimum hydroxide concentration be 0.4 molar. It was also recommended that the hydroxide concentration not stay below 0.4 molar for longer than 45 days

  17. Fermi level equilibration between colloidal lead and silver particles in aqueous solution

    International Nuclear Information System (INIS)

    Henglein, A.; Holzwarth, A.; Mulvaney, P.

    1992-01-01

    Colloidal solutions of lead and silver were mixed under the exclusion of air. The equilibration of the Fermi levels in the two different types of metal particles took place over a few days at room temperature. The equilibration took place by the transfer of lead atoms from lead to silver particles until the latter carried a lead mantle of one to two monolayers. This could be concluded from the observed changes in the optical spectrum of the silver particles. The results are discussed in terms of two mechanisms: (1) Pb atom transfer following heterocoagulation of the lead and silver particles and (2) electron transfer during Brownian encounters, followed by Pb 2+ desorption from the lead particles and subsequent Pb 2+ reductor on the silver particles carrying the transferred electrons. Traces of methylviologen, MV 2+ , in the solution drastically increase the rate of equilibration; this is explained by a relay mechanism in which electrons in the lead particles are first picked up by MV 2+ and are then transferred from MV + to the silver particles. 2 refs., 4 figs

  18. Effects of milk curd on saliva secretion in healthy volunteer compared to baseline, 2% pilocarpine and equivalent pH adjusted acetic acid solutions.

    Science.gov (United States)

    Babaee, Neda; Gholizadehpasha, Atefeh; Zahedpasha, Samir; Moghadamnia, Yasaman; Zamaninejad, Shiva; Moghadamnia, Ali Akbar

    2011-01-01

    Dry mouth is a common clinical problem, and different products have been proposed to improve it. In this investigation, the effects of "milk curd" on the amount of saliva secretion were studied. A total of 32 patients (aged 20-30) were selected from healthy volunteers. Milk curd concentrations of 0.5, 1, 2 and 4%, and 2% pilocarpine were prepared as drops. The impact of the drugs on the saliva weight was assessed after 1-5 min. To determine the effects of the pH of the milk curd on the amount of saliva secretion, different concentrations of acetic acid were used. At the end of the first minute, the differences between the data for all groups were statistically significant, and the difference between the 2% and 4% milk curd groups was higher than the others (P saliva secreted at the end of the second minute between the baseline and 4% milk curd groups and between the 0.5% and 4% MC groups were significant (P = 0.006 and P = 0.025, respectively). In total, there was no significant difference between the effect of various pH treatments and the amount of baseline saliva secretion. Milk curd has a significant local impact, and the saliva increase depends on the dose. It seems that this effect is not only related to its acidic taste. As a result, factors other than pH are involved in the effect.

  19. Trace level detection of explosives in solution using leidenfrost phenomenon assisted thermal desorption ambient mass spectrometry.

    Science.gov (United States)

    Saha, Subhrakanti; Mandal, Mridul Kanti; Chen, Lee Chuin; Ninomiya, Satoshi; Shida, Yasuo; Hiraoka, Kenzo

    2013-01-01

    The present paper demonstrates the detection of explosives in solution using thermal desorption technique at a temperature higher than Leidenfrost temperature of the solvent in combination with low temperature plasma (LTP) ionization. Leidenfrost temperature of a solvent is the temperature above which the solvent droplet starts levitation instead of splashing when placed on a hot metallic surface. During this desorption process, slow and gentle solvent evaporation takes place, which leads to the pre-concentration of less-volatile explosive molecules in the droplet and the explosive molecules are released at the last moment of droplet evaporation. The limits of detection for explosives studied by using this thermal desorption LTP ionization method varied in a range of 1 to 10 parts per billion (ppb) using a droplet volume of 20 μL (absolute sample amount 90-630 fmol). As LTP ionization method was applied and ion-molecule reactions took place in ambient atmosphere, various ion-molecule adduct species like [M+NO2](-), [M+NO3](-), [M+HCO3](-), [M+HCO4](-) were generated together with [M-H](-) peak. Each peak was unambiguously identified using 'Exactive Orbitrap' mass spectrometer in negative ionization mode within 3 ppm deviation compared to its exact mass. This newly developed technique was successfully applied to detect four explosives contained in the pond water and soil sample with minor sample pre-treatment and the explosives were detected with ppb levels. The present method is simple, rapid and can detect trace levels of explosives with high specificity from solutions.

  20. Solutions for ecosystem-level protection of ocean systems under climate change.

    Science.gov (United States)

    Queirós, Ana M; Huebert, Klaus B; Keyl, Friedemann; Fernandes, Jose A; Stolte, Willem; Maar, Marie; Kay, Susan; Jones, Miranda C; Hamon, Katell G; Hendriksen, Gerrit; Vermard, Youen; Marchal, Paul; Teal, Lorna R; Somerfield, Paul J; Austen, Melanie C; Barange, Manuel; Sell, Anne F; Allen, Icarus; Peck, Myron A

    2016-12-01

    The Paris Conference of Parties (COP21) agreement renewed momentum for action against climate change, creating the space for solutions for conservation of the ocean addressing two of its largest threats: climate change and ocean acidification (CCOA). Recent arguments that ocean policies disregard a mature conservation research field and that protected areas cannot address climate change may be oversimplistic at this time when dynamic solutions for the management of changing oceans are needed. We propose a novel approach, based on spatial meta-analysis of climate impact models, to improve the positioning of marine protected areas to limit CCOA impacts. We do this by estimating the vulnerability of ocean ecosystems to CCOA in a spatially explicit manner and then co-mapping human activities such as the placement of renewable energy developments and the distribution of marine protected areas. We test this approach in the NE Atlantic considering also how CCOA impacts the base of the food web which supports protected species, an aspect often neglected in conservation studies. We found that, in this case, current regional conservation plans protect areas with low ecosystem-level vulnerability to CCOA, but disregard how species may redistribute to new, suitable and productive habitats. Under current plans, these areas remain open to commercial extraction and other uses. Here, and worldwide, ocean conservation strategies under CCOA must recognize the long-term importance of these habitat refuges, and studies such as this one are needed to identify them. Protecting these areas creates adaptive, climate-ready and ecosystem-level policy options for conservation, suitable for changing oceans. © 2016 John Wiley & Sons Ltd.

  1. EFFECT OF RICE STRAW AND NITRATE LEVELS IN SOIL SOLUTION ON NITROUS OXIDE EMISSION

    Directory of Open Access Journals (Sweden)

    André Carlos Cruz Copetti

    2015-04-01

    Full Text Available Among the greenhouse gases, nitrous oxide (N2O is considered important, in view of a global warming potential 296 times greater than that of carbon dioxide (CO2 and its dynamics strongly depend on the availability of C and mineral N in the soil. The understanding of the factors that define emissions is essential to develop mitigation strategies. This study evaluated the dynamics of N2O emissions after the application of different rice straw amounts and nitrate levels in soil solution. Pots containing soil treated with sodium nitrate rates (0, 50 and 100 g kg-1 of NO−3-N and rice straw levels (0, 5 and 10 Mg ha-1, i.e., nine treatments, were subjected to anaerobic conditions. The results showed that N2O emissions were increased by the addition of greater NO−3 amounts and reduced by large straw quantities applied to the soil. On the 1st day after flooding (DAF, significantly different N2O emissions were observed between the treatments with and without NO−3 addition, when straw had no significant influence on N2O levels. Emissions peaked on the 4th DAF in the treatments with highest NO−3-N addition. At this moment, straw application negatively affected N2O emissions, probably due to NO−3 immobilization. There were also alterations in other soil electrochemical characteristics, e.g., higher straw levels raised the Fe, Mn and dissolved C contents. These results indicate that a lowering of NO−3 concentration in the soil and the increase of straw incorporation can decrease N2O emissions.

  2. Effects of milk curd on saliva secretion in healthy volunteer compared to baseline, 2% pilocarpine and equivalent pH adjusted acetic acid solutions

    Directory of Open Access Journals (Sweden)

    Neda Babaee

    2011-01-01

    Full Text Available Background: Dry mouth is a common clinical problem, and different products have been proposed to improve it. In this investigation, the effects of "milk curd" on the amount of saliva secretion were studied. Materials and Methods: A total of 32 patients (aged 20-30 were selected from healthy volunteers. Milk curd concentrations of 0.5, 1, 2 and 4%, and 2% pilocarpine were prepared as drops. The impact of the drugs on the saliva weight was assessed after 1-5 min. To determine the effects of the pH of the milk curd on the amount of saliva secretion, different concentrations of acetic acid were used. Results: At the end of the first minute, the differences between the data for all groups were statistically significant, and the difference between the 2% and 4% milk curd groups was higher than the others (P < 0.0001. The differences in the amount of the saliva secreted at the end of the second minute between the baseline and 4% milk curd groups and between the 0.5% and 4% MC groups were significant (P = 0.006 and P = 0.025, respectively. In total, there was no significant difference between the effect of various pH treatments and the amount of baseline saliva secretion. Conclusion: Milk curd has a significant local impact, and the saliva increase depends on the dose. It seems that this effect is not only related to its acidic taste. As a result, factors other than pH are involved in the effect.

  3. Influence of variation in mobile phase pH and solute pK(a) with the change of organic modifier fraction on QSRRs of hydrophobicity and RP-HPLC retention of weakly acidic compounds.

    Science.gov (United States)

    Han, Shu-ying; Liang, Chao; Zou, Kuan; Qiao, Jun-qin; Lian, Hong-zhen; Ge, Xin

    2012-11-15

    The variation in mobile phase pH and ionizable solute dissociation constant (pK(a)) with the change of organic modifier fraction in hydroorganic mobile phase has seemingly been a troublesome problem in studies and applications of reversed phase high performance liquid chromatography (RP-HPLC). Most of the early studies regarding the RP-HPLC of acid-base compounds have to measure the actual pH of the mixed mobile phase rigorously, sometimes bringing difficulties in the practices of liquid chromatographic separation. In this paper, the effect of this variation on the apparent n-octanol/water partition coefficient (K(ow)″) and the related quantitative structure-retention relationship (QSRR) of logK(ow)″ vs. logk(w), the logarithm of retention factor of analytes in neat aqueous mobile phases, was investigated for weakly acidic compounds. This QSRR is commonly used as a classical method for K(ow) measurement by RP-HPLC. The theoretical and experimental derivation revealed that the variation in mobile phase pH and solute pK(a) will not affect the QSRRs of acidic compounds. This conclusion is proved to be suitable for various types of ion-suppressors, i.e., strong acid (perchloric acid), weak acid (acetic acid) and buffer salt (potassium dihydrogen phosphate/phosphoric acid, PBS). The QSRRs of logK(ow)″ vs. logk(w) were modeled by 11 substituted benzoic acids using different types of ion-suppressors in a binary methanol-water mobile phase to confirm our deduction. Although different types of ion-suppressor all can be used as mobile phase pH modifiers, the QSRR model obtained by using perchloric acid as the ion-suppressor was found to have the best result, and the slightly inferior QSRRs were obtained by using acetic acid or PBS as the ion-suppressor. Copyright © 2012 Elsevier B.V. All rights reserved.

  4. Less is More: Membrane Protein Digestion Beyond Urea–Trypsin Solution for Next-level Proteomics*

    Science.gov (United States)

    Zhang, Xi

    2015-01-01

    The goal of next-level bottom-up membrane proteomics is protein function investigation, via high-coverage high-throughput peptide-centric quantitation of expression, modifications and dynamic structures at systems scale. Yet efficient digestion of mammalian membrane proteins presents a daunting barrier, and prevalent day-long urea–trypsin in-solution digestion proved insufficient to reach this goal. Many efforts contributed incremental advances over past years, but involved protein denaturation that disconnected measurement from functional states. Beyond denaturation, the recent discovery of structure/proteomics omni-compatible detergent n-dodecyl-β-d-maltopyranoside, combined with pepsin and PNGase F columns, enabled breakthroughs in membrane protein digestion: a 2010 DDM-low-TCEP (DLT) method for H/D-exchange (HDX) using human G protein-coupled receptor, and a 2015 flow/detergent-facilitated protease and de-PTM digestions (FDD) for integrative deep sequencing and quantitation using full-length human ion channel complex. Distinguishing protein solubilization from denaturation, protease digestion reliability from theoretical specificity, and reduction from alkylation, these methods shifted day(s)-long paradigms into minutes, and afforded fully automatable (HDX)-protein-peptide-(tandem mass tag)-HPLC pipelines to instantly measure functional proteins at deep coverage, high peptide reproducibility, low artifacts and minimal leakage. Promoting—not destroying—structures and activities harnessed membrane proteins for the next-level streamlined functional proteomics. This review analyzes recent advances in membrane protein digestion methods and highlights critical discoveries for future proteomics. PMID:26081834

  5. Process for final storage of high level radioactive fission product solution

    International Nuclear Information System (INIS)

    Ellis, J.R.B.; Fries, B.A.

    1984-01-01

    In this process for the storage of an aqueous solution of radioactive nuclides, the solution is diluted with system water, which is obtained from a reservoir below the bottom of the sea in a porous geological stratum. After dilution, the diluted solution is injected into the same geological stratum under the bottom of the sea. (orig.) [de

  6. Efeito da concentração de coagulantes e do pH da solução na turbidez da água, em recirculação, utilizada no processamento dos frutos do cafeeiro Effects from the concentration of coagulants and pH solution on the turbidity of the recirculating water used in the coffee cherry processing

    Directory of Open Access Journals (Sweden)

    Antonio T. Matos

    2007-08-01

    Full Text Available Com o objetivo de determinar a dose e a faixa de pH dos coagulantes sulfato de alumínio (SA, sulfato ferroso clorado (SFC, cloreto férrico (CF e extrato de semente de moringa (ESM, que proporcionassem maior eficiência na remoção da turbidez na água residuária da despolpa de frutos do cafeeiro (ARDC, após serem efetuadas cinco recirculações, foram conduzidos ensaios de coagulação/floculação utilizando o aparelho "Jar-test". Todos esses coagulantes foram avaliados nas concentrações de 0; 0,5; 1,0; 1,5; 2,0; 2,5 e 3,0 g L-1. No caso da solução preparada com ESM, as doses utilizadas foram: 0; 10; 20; 30; 40; 50 e 60 mL L-1. O pH da solução em teste foi alterado, utilizando-se do hidróxido de sódio (NaOH, na concentração de 0,3 mol L-1, sendo avaliadas as faixas de 4,0 a 5,0; 5,0 a 6,0; 6,0 a 7,0 e 7,0 a 8,0. No ensaio de coagulação/floculação, o ESM proporcionou maior remoção de SS (sólidos em suspensão da ARDC com a dose de 10 mL L-1 e pH de 4,27 (natural. Para os coagulantes SA e CF, os melhores resultados foram obtidos com a concentração de 3 g L-1 e pH de 7,27 e, para o coagulante SFC, com a concentração de 3 g L-1 e pH de 4,27.Aiming the determination of the dose and pH range of the coagulants aluminum sulfate (AS, chlorinated ferrous sulfate (CFS, ferric chloride (FC and Moringa oleifera seed extract (MSE that would provide a higher efficiency in removing the turbidity from the coffee cherry pulping wastewater (CPW, five recirculations were accomplished and the coagulation/flocculation assays were conducted, by using the Jar-test device. The concentrations (0; 0.5; 1.0; 1.5; 2.0; 2.5 and 3.0 g L- 1 were evaluated. In the case of the MSE-prepared solution, the following doses were used: 0; 10; 20; 30; 40; 50 and 60 mL L-1. The pH of the solution under test was changed, by using the sodium hydroxide (NaOH at the concentration of 0.3 mol L-1, whereas the ranges from 4.0 to 5.0; 5.0 to 6.0; 6.0 to 7.0; and 7

  7. Adaptor protein containing PH domain, PTB domain and leucine zipper (APPL1) regulates the protein level of EGFR by modulating its trafficking

    International Nuclear Information System (INIS)

    Lee, Jae-Rin; Hahn, Hwa-Sun; Kim, Young-Hoon; Nguyen, Hong-Hoa; Yang, Jun-Mo; Kang, Jong-Sun; Hahn, Myong-Joon

    2011-01-01

    Highlights: ► APPL1 regulates the protein level of EGFR in response to EGF stimulation. ► Depletion of APPL1 accelerates the movement of EGF/EGFR from the cell surface to the perinuclear region in response to EGF. ► Knockdown of APPL1 enhances the activity of Rab5. -- Abstract: The EGFR-mediated signaling pathway regulates multiple biological processes such as cell proliferation, survival and differentiation. Previously APPL1 (adaptor protein containing PH domain, PTB domain and leucine zipper 1) has been reported to function as a downstream effector of EGF-initiated signaling. Here we demonstrate that APPL1 regulates EGFR protein levels in response to EGF stimulation. Overexpression of APPL1 enhances EGFR stabilization while APPL1 depletion by siRNA reduces EGFR protein levels. APPL1 depletion accelerates EGFR internalization and movement of EGF/EGFR from cell surface to the perinuclear region in response to EGF treatment. Conversely, overexpression of APPL1 decelerates EGFR internalization and translocation of EGF/EGFR to the perinuclear region. Furthermore, APPL1 depletion enhances the activity of Rab5 which is involved in internalization and trafficking of EGFR and inhibition of Rab5 in APPL1-depleted cells restored EGFR levels. Consistently, APPL1 depletion reduced activation of Akt, the downstream signaling effector of EGFR and this is restored by inhibition of Rab5. These findings suggest that APPL1 is required for EGFR signaling by regulation of EGFR stabilities through inhibition of Rab5.

  8. Response of Listeria monocytogenes to disinfection stress at the single-cell and population levels as monitored by intracellular pH measurements and viable-cell counts

    DEFF Research Database (Denmark)

    Kastbjerg, Vicky Gaedt; Nielsen, Dennis S.; Arneborg, Nils

    2009-01-01

    of the bacterium. In situ analyses of Listeria monocytogenes single cells were performed during exposure to different concentrations of the disinfectant Incimaxx DES to study a possible population subdivision. Bacterial survival was quantified with plate counting and disinfection stress at the single-cell level...... by measuring intracellular pH (pHi) over time by fluorescence ratio imaging microscopy. pHi values were initially 7 to 7.5 and decreased in both attached and planktonic L. monocytogenes cells during exposure to sublethal and lethal concentrations of Incimaxx DES. The response of the bacterial population...... was homogenous; hence, subpopulations were not detected. However, pregrowth with NaCl protected the planktonic bacterial cells during disinfection with Incimaxx (0.0015%) since pHi was higher (6 to 6.5) for the bacterial population pregrown with NaCl than for cells grown without NaCl (pHi 5 to 5.5) (P

  9. Uremic retention solute indoxyl sulfate level is associated with prolonged QTc interval in early CKD patients.

    Directory of Open Access Journals (Sweden)

    Wei-Hua Tang

    Full Text Available Total mortality and sudden cardiac death is highly prevalent in patients with chronic kidney disease (CKD. In CKD patients, the protein-bound uremic retention solute indoxyl sulfate (IS is independently associated with cardiovascular disease. However, the underlying mechanisms of this association have yet to be elucidated. The relationship between IS and cardiac electrocardiographic parameters was investigated in a prospective observational study among early CKD patients. IS arrhythmogenic effect was evaluated by in vitro cardiomyocyte electrophysiological study and mathematical computer simulation. In a cohort of 100 early CKD patients, patients with corrected QT (QTc prolongation had higher IS levels. Furthermore, serum IS level was independently associated with prolonged QTc interval. In vitro, the delay rectifier potassium current (IK was found to be significantly decreased after the treatment of IS in a dose-dependent manner. The modulation of IS to the IK was through the regulation of the major potassium ion channel protein Kv 2.1 phosphorylation. In a computer simulation, the decrease of IK by IS could prolong the action potential duration (APD and induce early afterdepolarization, which is known to be a trigger mechanism of lethal ventricular arrhythmias. In conclusion, serum IS level is independently associated with the prolonged QTc interval in early CKD patients. IS down-regulated IK channel protein phosphorylation and the IK current activity that in turn increased the cardiomyocyte APD and QTc interval in vitro and in the computer ORd model. These findings suggest that IS may play a role in the development of arrhythmogenesis in CKD patients.

  10. Investigations of actinides in the context of final disposal of high-level radioactive waste. Trivalent actinides in aqueous solution

    International Nuclear Information System (INIS)

    Banik, N.L.; Boris Brendebach; Marquardt, Ch.M.

    2014-01-01

    The speciation of redox sensitive trivalent actinides Pu(III), Np(III), and U(III) has been studied in aqueous solution. The redox preparation, stabilization, and speciation of these trivalent actinides in aqueous systems are discussed here. The reductants investigated were rongalite, hydroxylamine hydrochloride, and acetohydroxamic acid and the An(III) species have been characterized by UV-Vis and XANES spectroscopy. The results show that the effectiveness of stabilization decreases generally in the order Pu(III) > Np(III) > U(III) and that the effectiveness of each reducing agent depends on the experimental conditions. More than 80 % of Pu(III) aquo species have been stabilized up to pH 5.5, whereas the Np(III) aquo ion could be stabilized in a pH range 0-2.5, and U(III) aquo ion is sufficiently stable at pH 1.0 and below over time periods suitable for experiments. However, this study gives a basis for the characterisation of the trivalent lighter actinides involved in complexation, sorption, and solid formation reactions in the future. (author)

  11. Carbon steel protection in G.S. (Girlder sulfide) plants. A protective layer formation in saturated solution of sulfohydric acid in water at pH = 4.43. Pt. 3

    International Nuclear Information System (INIS)

    Bruzzoni, P.; Burkart, A.L.; Garavaglia, R.N.

    1985-04-01

    As complement to the experiences on carbon steel passivation for its use in G.S. (Girlder sulfide) heavy water production plants, the results herein obtained are given, processing the material with a saturated solution at 2.3 MPa of full pressure and 125 temperature degree of H 2 S in NaOH 5 x 10 -3 M, which, at an equilibrium point, the pH is 4.43. The characteristics, the composition and adherence to the layer formed and the corrosion velocity data are analyzed. (Author) [es

  12. The Influence of pH and Temperature on the Stability of N-[(Piperidinemethylene]daunorubicin Hydrochloride and a Comparison of the Stability of Daunorubicin and Its Four New Amidine Derivatives in Aqueous Solutions

    Directory of Open Access Journals (Sweden)

    Mikołaj Piekarski

    2014-01-01

    Full Text Available The influence of pH and temperature on the stability of N-[(piperidinemethylene]daunorubicin hydrochloride (PPD was investigated. Degradation was studied using an HPLC method. Specific acid-base catalysis of PPD involves hydrolysis of protonated molecules of PPD catalyzed by hydrogen ions and spontaneous hydrolysis under the influence of water zwitterions, unprotonated molecules, and monoanions of PPD. The thermodynamic parameters of these reactions, energy, enthalpy, and entropy, were calculated. Also, the stability of daunorubicin and its new amidine derivatives (piperidine, morpholine, pyrrolidine, and hexahydroazepin-1-yl in aqueous solutions was compared and discussed.

  13. Zn availability in nutrient solutions for cucumber (Cucumis sativus L) in hydroponics as affected by Fe-chelates and pH

    NARCIS (Netherlands)

    Voogt, W.; Sonneveld, C.

    2017-01-01

    In soil-less culture systems Fe is usually supplied as chelate to ensure an adequate availability of this element. As chelates have affinity for many metal ions these chelates will interact with other cation nutrients in nutrient solutions. This affects the availability of Fe and other nutrients.

  14. Partitioning of organic matter and heavy metals in a sandy soil: Effects of extracting solution, solid to liquid ratio and pH

    NARCIS (Netherlands)

    Fest, P.M.J.; Temminghoff, E.J.M.; Comans, R.N.J.; Riemsdijk, van W.H.

    2008-01-01

    In sandy soils the behavior of heavy metals is largely controlled by soil organic matter (solid and dissolved organic matter; SOC and DOC). Therefore, knowledge of the partitioning of organic matter between the solid phase and soil solution is essential for adequate predictions of the total

  15. Skeletal muscle intracellular pH and levels of high energy phosphates during hypercapnia in intact lizards by 31P NMR

    International Nuclear Information System (INIS)

    Johnson, D.C.; Hitzig, B.M.; Elmden, K.; McFarland, E.; Koutcher, J.; Kazemi, H.

    1986-01-01

    Lizards have been shown to reduce ventilation during CO 2 breathing. This is thought to be detrimental to the maintenance of intracellular pH (pHi) and levels of high energy phosphates. The authors subjected chameleons (n=4) to 5% CO 2 breathing and made serial measurements of tail (skeletal) muscle pHi, levels of phosphocreatine (PCr), and ATP utilizing high resolution 31 P NMR. pHi was unchanged from controls (7.27 +/- 0.06 units) (mean +/- SE) during 30 minutes of hypercapnia (7.19 +/- 0.09 units) (p>.2) demonstrating effective regulation of skeletal muscle pHi; however, there were significant decreases in the PCr/ATP ratios to 65% +/- 5% (p 2 availability because there were no increases in the levels of glycolytic intermediates and inorganic phosphate which would indicate tissue hypoxia. It is possible that an active process requiring ATP is required for the maintenance of pHi in the presence of hypercapnia and that the reduction of PCr/ATP ratio is a reflection of an increased utilization of ATP

  16. Solubility and speciation of actinides in salt solutions and migration experiments of intermediate level waste in salt formations

    International Nuclear Information System (INIS)

    1986-01-01

    A comprehensive study into the solubility of the actinides americium and plutonium in concentrated salt solutions, the release of radionuclides from various forms of conditioned ILW and the migration behaviour of these nuclides through geological material specific to the Gorleben site in Lower Saxony is described. A detailed investigation into the characterization of four highly concentrated salt solutions in terms of their pH, Eh, inorganic carbon contents and their densities is given and a series of experiments investigating the solubility of standard americium(III) and plutonium(IV) hydroxides in these solutions is described. Transuranic mobility studies for solutions derived from the standard hydroxides through salt and sand have shown the presence of at least two types of species present of widely differing mobility; one migrating with approximately the same velocity as the solvent front and the other strongly retarded. Actinide mobility data are presented and discussed for leachates derived from the simulated ILW in cement and data are also presented for the migration of the fission products in leachates derived from real waste solidified in cement and bitumen. Relatively high plutonium mobilities were observed in the case of the former and in the case of the real waste leachates, cesium was found to be the least retarded. The sorption of ruthenium was found to be largely associated with the insoluble residues of the natural rock salt rather than the halite itself. (orig./RB)

  17. Less is More: Membrane Protein Digestion Beyond Urea-Trypsin Solution for Next-level Proteomics.

    Science.gov (United States)

    Zhang, Xi

    2015-09-01

    The goal of next-level bottom-up membrane proteomics is protein function investigation, via high-coverage high-throughput peptide-centric quantitation of expression, modifications and dynamic structures at systems scale. Yet efficient digestion of mammalian membrane proteins presents a daunting barrier, and prevalent day-long urea-trypsin in-solution digestion proved insufficient to reach this goal. Many efforts contributed incremental advances over past years, but involved protein denaturation that disconnected measurement from functional states. Beyond denaturation, the recent discovery of structure/proteomics omni-compatible detergent n-dodecyl-β-d-maltopyranoside, combined with pepsin and PNGase F columns, enabled breakthroughs in membrane protein digestion: a 2010 DDM-low-TCEP (DLT) method for H/D-exchange (HDX) using human G protein-coupled receptor, and a 2015 flow/detergent-facilitated protease and de-PTM digestions (FDD) for integrative deep sequencing and quantitation using full-length human ion channel complex. Distinguishing protein solubilization from denaturation, protease digestion reliability from theoretical specificity, and reduction from alkylation, these methods shifted day(s)-long paradigms into minutes, and afforded fully automatable (HDX)-protein-peptide-(tandem mass tag)-HPLC pipelines to instantly measure functional proteins at deep coverage, high peptide reproducibility, low artifacts and minimal leakage. Promoting-not destroying-structures and activities harnessed membrane proteins for the next-level streamlined functional proteomics. This review analyzes recent advances in membrane protein digestion methods and highlights critical discoveries for future proteomics. © 2015 by The American Society for Biochemistry and Molecular Biology, Inc.

  18. A comparative study of the metastable equilibrium solubility behavior of high-crystallinity and low-crystallinity carbonated apatites using pH and solution strontium as independent variables.

    Science.gov (United States)

    Heslop, D D; Bi, Y; Baig, A A; Otsuka, M; Higuchi, W I

    2005-09-01

    Using solution strontium and pH as independent variables, the metastable equilibrium solubility (MES) behavior of two carbonated apatite (CAP) samples has been examined, a high-crystallinity CAP (properties expected to be similar to dental enamel) and a low-crystallinity CAP (properties expected to be similar to bone mineral). CAP samples were prepared by precipitation/digestion: (CAP A: high-crystallinity, 1.3 wt% CO3, synthesized at 85 degrees C; CAP B: low-crystallinity, 6.4 wt% CO3, synthesized at 50 degrees C). Baseline MES distributions were determined in a series of 0.1 M acetate buffers containing only calcium and phosphate (no strontium) over a broad range of solution conditions. To assess the influence of strontium, MES profiles were determined in a similar fashion with 20, 40, 60, and 80% of the solution calcium being replaced on an equal molar basis by solution strontium. To determine the correct function governing CAP dissolution, ion activity products (IAPs) were calculated from the compositions of buffer solutions based on the hydroxyapatite template (Ca(10-n)Sr(n)(PO4)6(OH)2 (n = 0-10)) and the calcium/hydroxide deficient hydroxyapatite template (Ca(9-n)Sr(n)(HPO4)(PO4)5OH (n = 0-9)). (a) for CAP A, at high solution strontium/calcium ratios, the MES profiles were essentially superimposable when the solution IAPs were calculated using the stoichiometry of Ca6Sr4(PO4)6(OH)2 and for CAP B by a stoichiometry of Ca7Sr2(HPO4)(PO4)5OH; (b) for CAP A, at low strontium/calcium ratios, the stoichiometry yielding MES data superpositioning was found to be that of hydroxyapatite and for CAP B, that of calcium/hydroxide deficient hydroxyapatite. When other stoichiometries were assumed, good superpositioning of the data was not possible.

  19. Direct measurement of CO2 solubility and pH in NaCl hydrothermal solutions by combining in-situ potentiometry and Raman spectroscopy up to 280 °C and 150 bar

    Science.gov (United States)

    Truche, Laurent; Bazarkina, Elena F.; Berger, Gilles; Caumon, Marie-Camille; Bessaque, Gilles; Dubessy, Jean

    2016-03-01

    The in-situ monitoring of aqueous solution chemistry at elevated temperatures and pressures is a major challenge in geochemistry. Here, we combined for the first time in-situ Raman spectroscopy for concentration measurements and potentiometry for pH measurement in a single hydrothermal cell equipped with sampling systems and operating under controlled conditions of temperature and pressure. Dissolved CO2 concentration and pH were measured at temperatures up to 280 °C and pressures up to 150 bar in the H2O-CO2 and H2O-CO2-NaCl systems. A Pitzer specific-ion-interaction aqueous model was developed and confirmed the accuracy and consistency of the measurements, at least up to 250 °C. The revised Pitzer parameters for the H2O-CO2-NaCl system were formatted for the Phreeqc geochemical software. Significant changes with respect to the Pitzer.dat database currently associated with Phreeqc were observed. The new model parameters are now available for further applications. The Raman and pH probes tested here may also be applied to field monitoring of hydrothermal springs, geothermal wells, and oil and gas boreholes.

  20. Deep and shallow acceptor levels in solid solutions Pb0.98Sm0.02S

    International Nuclear Information System (INIS)

    Hasanov, H.A.; Rahimov, R.Sh.

    2010-01-01

    It is well known that the metal vacancies the energy levels of which take place between permitted energies of valency band, are the main acceptor centers in the led salts and solid solutions on their base. The aim of the given paper is founding of character of acceptor levels in single crystals Pb 0 .98Sm 0 .02S with low concentrations of charge carrier. The deep and shallow acceptor levels are found at investigation of Hall effect in Pb 0 .98Sm 0 .02S solid solution with character of low concentrations of charge carriers in crystals

  1. Virucidal activities of medium- and long-chain fatty alcohols and lipids against respiratory syncytial virus and parainfluenza virus type 2: comparison at different pH levels.

    Science.gov (United States)

    Hilmarsson, H; Traustason, B S; Kristmundsdóttir, T; Thormar, H

    2007-01-01

    Recent studies have shown that some lipids and fatty alcohols have microbicidal activities against a broad variety of pathogens. In this study, virucidal activities of fatty acids, monoglycerides and fatty alcohols were tested against respiratory syncytial virus (RSV) and human parainfluenza virus type 2 (HPIV2) at different concentrations, times and pH levels. The most active compounds were mixed with milk products and fruit juices and the mixtures tested for virucidal effects. The aim was to determine which compounds are the most active against these respiratory viruses and could possibly be used in pharmaceutical formulations or as additives to milk products or juice. Several compounds caused a significant inactivation of virus, and there was generally a good agreement between the activities against RSV and parainfluenza virus. By changing the pH from 7 to 4.2, the virucidal activities of some of the compounds were greatly increased, i.e., they inactivated virus in a shorter time and at lower concentrations. The most active compound tested was 1-monoglyceride of capric acid, monocaprin, which also showed activity against influenza A virus and significant virucidal activities after addition to milk products and fruit juices, even at a concentration as low as 0.06-0.12%. The significant virucidal activities of fatty alcohols and lipids on RSV and parainfluenza virus demonstrated in this in vitro study raise the question of the feasibility of using such compounds as ingredients in pharmaceutical dosage forms against respiratory infections caused by these viruses, and possibly other paramyxo- and myxoviruses.

  2. Impact of low-level laser therapy on hyposalivation, salivary pH, and quality of life in head and neck cancer patients post-radiotherapy.

    Science.gov (United States)

    Palma, Luiz Felipe; Gonnelli, Fernanda Aurora Stabile; Marcucci, Marcelo; Dias, Rodrigo Souza; Giordani, Adelmo José; Segreto, Roberto Araújo; Segreto, Helena Regina Comodo

    2017-05-01

    Late effects of radiotherapy for head and neck cancer treatment have been increasingly investigated due to its impact on patients' quality of life. The purpose of this study was to evaluate the effect of low-level laser therapy on hyposalivation, low salivary pH, and quality of life in head and neck cancer patients post-radiotherapy. Twenty-nine patients with radiation-induced xerostomia received laser sessions twice a week, during 3 months (24 sessions). For this, a continuous wave Indium-Gallium-Aluminium-Phosphorus diode laser device was used punctually on the major salivary glands (808 nm, 0.75 W/cm 2 , 30 mW, illuminated area 0.04 cm 2 , 7.5 J/cm 2 , 10 s, 0.3 J). Six extraoral points were illuminated on each parotid gland and three on each submandibular gland, as well as two intraoral points on each sublingual gland. Stimulated and unstimulated salivary flow rate, pH (two scales with different gradations), and quality of life (University Of Washington Quality of Life Questionnaire for Patients with Head and Neck Cancer) were assessed at baseline and at the end of the treatment. There were significant increases in both mean salivary flow rates (unstimulated: p = 0.0012; stimulated: p quality of life questionnaire (p patients submitted to radiotherapy for head and neck cancer, thereby leading to an improvement in quality of life.

  3. Electrochemical characteristics of bioresorbable binary MgCa alloys in Ringer's solution: Revealing the impact of local pH distributions during in-vitro dissolution

    Energy Technology Data Exchange (ETDEWEB)

    Mareci, D., E-mail: danmareci@yahoo.com [Faculty of Chemical Engineering and Environmental Protection, The “Gheorghe Asachi” Technical University of Iasi, 700050, Iasi (Romania); Bolat, G. [Faculty of Chemical Engineering and Environmental Protection, The “Gheorghe Asachi” Technical University of Iasi, 700050, Iasi (Romania); Izquierdo, J. [Department of Chemistry, University of La Laguna, P.O. Box 456, E-38200 La Laguna (Tenerife) (Spain); Crimu, C.; Munteanu, C. [Faculty of Mechanical Engineering, The “Gheorghe Asachi” Technical University of Iasi, 700050, Iasi (Romania); Antoniac, I. [Faculty of Materials Science and Engineering, Politehnica of Bucharest, 060042 Bucharest (Romania); Souto, R.M., E-mail: rsouto@ull.es [Department of Chemistry, University of La Laguna, P.O. Box 456, E-38200 La Laguna (Tenerife) (Spain); Faculty of Materials Science and Engineering, Politehnica of Bucharest, 060042 Bucharest (Romania)

    2016-03-01

    Biodegradable magnesium–calcium (MgCa) alloy is a very attractive biomaterial. Two MgCa alloys below the solid solubility of Ca were considered, as to solely investigate the effect of Ca content on the behavior of magnesium and the pH changes associated to metal dissolution. X-ray diffraction analysis and optical microscopy showed that both Mg–0.63Ca and Mg–0.89Ca alloys were solely composed of α(Mg) phase. Degradation characteristics and electrochemical characterization of MgCa alloys were investigated during exposure to Ringer's solution at 37 °C by electrochemical impedance spectroscopy and scanning electrochemical microscopy. The impedance behavior showed both capacitive and inductive features that are related to the alloy charge transfer reaction and the relaxation of the absorbed corrosion compounds, and can be described in terms of an equivalent circuit. Scanning electron microscopy (SEM) was employed to view the surface morphology of the MgCa samples after 1 week immersion in Ringer's solution showing extensive precipitation of corrosion products, whereas the substrate shows evidence of a non-uniform corrosion process. Energy dispersive analysis showed that the precipitates contained oxygen, calcium, magnesium and chlorine, and the Mg:Ca ratios were smaller than in the alloys. Scanning electrochemical microscopy (SECM) was used to visualize local pH changes associated to these physicochemical processes with high spatial resolution. The occurrence of pH variations in excess of 3 units between anodic and cathodic half-cell reactions was monitored in situ. - Highlights: • Spontaneous degradation of MgCa alloys in Ringer's solution characterized at 37 °C • Reactivity differences between Mg0.63Ca and Mg0.89Ca are evidenced using multiscale electrochemical characterization. • Electrochemical activation occurs heterogeneously on the alloy surface. • Metal dissolution is accompanied by local pH changes. • Mg0.63Ca degrades faster

  4. Influence of solution pH on the electron transport of the self-assembled nanoarrays of single-walled carbon nanotube-cobalt tetra-aminophthalocyanine on gold electrodes: Electrocatalytic detection of epinephrine

    Energy Technology Data Exchange (ETDEWEB)

    Ozoemena, Kenneth I. [Chemistry Department, University of Pretoria, Pretoria 0002 (South Africa)], E-mail: kenneth.ozoemena@up.ac.za; Nkosi, Dudu; Pillay, Jeseelan [Chemistry Department, University of Pretoria, Pretoria 0002 (South Africa)

    2008-02-15

    This paper provides first evidence of the impact of solution pH on the heterogeneous electron transfer rate constants of self-assembled films of single-walled carbon nanotubes (SWCNT) and SWCNT integrated to cobalt(II)tetra-aminophthalocyanine (SWCNT-CoTAPc) by sequential self-assembly. Using cyclic voltammetry and electrochemical impedance spectroscopy, we proved that both SAMs exhibit notable differences in their response to different buffered solution pH, with and without the presence of redox probe, [Fe(CN){sub 6}]{sup 4-}/[Fe(CN){sub 6}]{sup 3-}. Surface pK{sub a} value for the Au-Cys-SWCNT-CoTAPc was estimated as ca. 7.8, compared to that of the Au-Cys-SWCNT of about 5.5. Interestingly, both redox-active SAMs gave similar analytical response for epinephrine, giving well-resolved square wave voltammograms, with linear concentration range up to 130 {mu}M, sensitivity of ca. 9.4 x 10{sup -3} AM{sup -1}, and limit of detection ca. 6 {mu}M. This analytical result implies that there is no detectable advantage of one of the SAMs over the other in the electrocatalytic detection of this neurotransmitter.

  5. Deposition and separation of W and Mo from aqueous solutions with simultaneous hydrogen production in stacked bioelectrochemical systems (BESs): Impact of heavy metals W(VI)/Mo(VI) molar ratio, initial pH and electrode material.

    Science.gov (United States)

    Huang, Liping; Li, Ming; Pan, Yuzhen; Quan, Xie; Yang, Jinhui; Puma, Gianluca Li

    2018-04-16

    The deposition and separation of W and Mo from aqueous solutions with simultaneous hydrogen production was investigated in stacked bioelectrochemical systems (BESs) composed of microbial electrolysis cell (1#) serially connected with parallel connected microbial fuel cell (2#). The impact of W/Mo molar ratio (in the range 0.01 mM : 1 mM and vice-versa), initial pH (1.5 to 4.0) and cathode material (stainless steel mesh (SSM), carbon rod (CR) and titanium sheet (TS)) on the BES performance was systematically investigated. The concentration of Mo(VI) was more influential than W(VI) in determining the rate of deposition of both metals and the rate of hydrogen production. Complete metal recovery was achieved at equimolar W/Mo ratio of 0.05 mM : 0.05 mM. The rates of metal deposition and hydrogen production increased at acidic pH, with the fastest rates at pH 1.5. The morphology of the metal deposits and the valence of the Mo were correlated with W/Mo ratio and pH. CR cathodes (2#) coupled with SSM cathodes (1#) achieved a significant rate of hydrogen production (0.82 ± 0.04 m 3 /m 3 /d) with W and Mo deposition (0.049 ± 0.003 mmol/L/h and 0.140 ± 0.004 mmol/L/h (1#); 0.025 ± 0.001 mmol/L/h and 0.090 ± 0.006 mmol/L/h (2#)). Copyright © 2018 Elsevier B.V. All rights reserved.

  6. The Effect of Micro/Nano-metrics Size on the Interaction of Jordanian Aluminosilicate Raw Materials with High pH Solution

    Science.gov (United States)

    Aldabsheh, Islam; Garcia-Valles, Maite; Martinez, Salvador

    2014-05-01

    Environmental preservation has become a driving force behind the search for new sustainable and environmentally friendly composites to replace conventional concrete produced from ordinary Portland cement (OPC). Current researches concentrate on developing building products (geopolymers) through geopolymerization. The goal is to produce low cost construction materials for green housing. Geopolymerization is the process of polymerizing minerals with high silica and alumina at low temperature by the use of alkali solutions. Dissolution is the most important process for supplying the high initial Al and Si concentrations to produce the gel phase that is responsible for geopolymerization. This study has been focused on the influence of different micrometric particle sizes of three Jordanian raw materials on their dissolution behavior in sodium hydroxide solution. The samples are kaolinite, volcanic tuff and silica sand. The dissolution properties of each material, alone and mixed with the other two materials were studied in different concentrations (5 and 10 M) using (NaOH) at 25ºC, and shaking time for 24 and 168 h. To better understand the dissolution process, the alkaline solution was renewed after the desired time in order to know if the Al-Si raw material is completely dissolved or not. Different analytical techniques were used to characterize raw materials physically, mineralogically, chemically and thermally. All processed samples either centrifuged solutions or solid residues were fully characterized. The leached concentrations of Al and Si were determined by inductively coupled plasma (ICP). X-ray Diffraction Technique (XRD), Scanning Electron Microscopy (SEM), and Thermo Gravimetric Analysis (TGA) were used to evaluate the solid residue characterization compared with the original ones. The three aluminosilicate raw materials have indicated variable degrees of solubility under highly alkaline conditions. The method for the size reduction of the used raw

  7. Optimal control of quantum dissipative dynamics: Analytic solution for cooling the three-level Λ system

    International Nuclear Information System (INIS)

    Sklarz, Shlomo E.; Tannor, David J.; Khaneja, Navin

    2004-01-01

    We study the problem of optimal control of dissipative quantum dynamics. Although under most circumstances dissipation leads to an increase in entropy (or a decrease in purity) of the system, there is an important class of problems for which dissipation with external control can decrease the entropy (or increase the purity) of the system. An important example is laser cooling. In such systems, there is an interplay of the Hamiltonian part of the dynamics, which is controllable, and the dissipative part of the dynamics, which is uncontrollable. The strategy is to control the Hamiltonian portion of the evolution in such a way that the dissipation causes the purity of the system to increase rather than decrease. The goal of this paper is to find the strategy that leads to maximal purity at the final time. Under the assumption that Hamiltonian control is complete and arbitrarily fast, we provide a general framework by which to calculate optimal cooling strategies. These assumptions lead to a great simplification, in which the control problem can be reformulated in terms of the spectrum of eigenvalues of ρ, rather than ρ itself. By combining this formulation with the Hamilton-Jacobi-Bellman theorem we are able to obtain an equation for the globally optimal cooling strategy in terms of the spectrum of the density matrix. For the three-level Λ system, we provide a complete analytic solution for the optimal cooling strategy. For this system it is found that the optimal strategy does not exploit system coherences and is a 'greedy' strategy, in which the purity is increased maximally at each instant

  8. The Impact of Solution-Focused Brief Group Psychological Counseling on University Students’ Burnout Levels

    Directory of Open Access Journals (Sweden)

    Azmi Bayram Ilbay

    2014-12-01

    Full Text Available This research was done to analyze the effects of Coping with Burnout Program, developed on the basis of Solution-Focused Brief Therapy on the burnout levels of university students. To select the subjects that would participate in the research, Maslach Burnout Inventory­­–Student Survey was applied on 461 university students from the University of Sakarya. As a result of pre-interviews, 24 students who had experienced student burnout voluntarily participated in a Coping with Burnout Program. The students were randomly appointed to one of the experimental and control groups. At this stage, a six-session Coping with Burnout Program developed by the researcher was applied on the students from the experimental group. No application was performed on the students from the control group. A 2x3 design (experimental/ control groups X pretest/ posttest/ follow up was used in the research. The scores from the Maslach Burnout Inventory–Student Survey formed the dependent variable of the research, and the application of Coping with Burnout Program formed the independent variable of the research. The scale used in the research was applied on the groups as pretest two weeks before the sessions started, and as posttest two weeks after the sessions ended, and as follow-up two months after the posttest in order to determine the resistance of the experimental process. In the analysis of the data obtained through these processes, two-way analysis of variance (ANOVA was used to determine whether or not there was a significant difference between groups and the survey. The data obtained through the research proved that the Coping with Burnout Program decreased the burnout levels of the students in the experimental group as were determined with the Maslach Burnout Inventory–Student Survey, and follow up tests showed that the situation remained the same. It was seen that there was no significant difference between the scores of the participants of the control

  9. Plant Habitat (PH)

    Science.gov (United States)

    Onate, Bryan

    2016-01-01

    The International Space Station (ISS) will soon have a platform for conducting fundamental research of Large Plants. Plant Habitat (PH) is designed to be a fully controllable environment for high-quality plant physiological research. PH will control light quality, level, and timing, temperature, CO2, relative humidity, and irrigation, while scrubbing ethylene. Additional capabilities include leaf temperature and root zone moisture and oxygen sensing. The light cap will have red (630 nm), blue (450 nm), green (525 nm), far red (730 nm) and broad spectrum white LEDs. There will be several internal cameras (visible and IR) to monitor and record plant growth and operations.

  10. O pH da calda de aplicação e a absorção de ácido giberélico por frutas de laranja cv. ‘Valência’ The solution pH on gibberellic acid uptake by cv. ‘Valência’ orange fruits

    Directory of Open Access Journals (Sweden)

    João Guilherme Casagrande Jr.

    1999-10-01

    different solution pH. The treatments consisted of 5 concentrations of gibberellic acid (0; 5; 10; 15; and 20 ppm and 3 pHs (3; 4.5; and 6. The aplication was made in May, when fruits were at green-yellow stage, and samples were collected every 30 days until November. The variables studied were coloration and thickness of the peel, total soluble solids (TSS, pH of juice, percent of juice, total acid (TA, ratio TSS/TA and technological index. The results obtained did not allow to conclude that gibberellic acid had any influence on the characteristics of the juice. The thickness of the peel was not affected by gibberellic acid. However, gibberellic acid caused a retaintion of the green color of the peel with increasing concentration, causing the fruits to remain greener. This was observed for all solution pHs. At pH 3, the fruits were greener than under the other pHs, and at the normal pH (4.5 The green coloration in the fruits persisted for a louger time than at pH=6, suggesting that acid pHs increase the uptake of gibberelic acid by the plants. It was also observed that gibberellic acid delayed the regreening of the fruits, what happens when the temperature becomes higher.

  11. PH-Sensitive Nanogels Synthesised by Radiation-Induced Cross-Linking of Hydrogen-Bonded Interpolymer Complexes in Aqueous Solution

    International Nuclear Information System (INIS)

    Ulanski, P.; Kadłubowski, S.; Henke, A.; Olejnik, A.K.; Rokita, B.; Wach, R.; Rosiak, J.M.

    2010-01-01

    Nanogels, i.e., internally cross-linked hydrophilic polymeric particles of sub-micron sizes, gained much interest over the last years due to their possible application as components of advanced type of medicines, like drug carriers. It is expected that they can facilitate distribution and delivery of different types of biologically active substances (including proteins, peptides and oligonucleotides) in a controlled way within the human body. Nanogels and their bigger analogues – microgels, are mainly synthesised through free-radical cross-linking polymerization of monomers. This synthetic routine can be carried out in solution but more often emulsion techniques are preferred (mini- or microemulsion) due to easier size control and exclusion of the macrogelation process. Additionally, surfactant-free emulsion polymerization (SFEP) is the method of choice for the preparation of temperature-sensitive particles, mainly based on poly(N-isopropylacrylamide).Nanogels were also successfully prepared by intramolecular cross-linking of single macromolecules. More recently, covalent stabilization was utilized to obtain the self-assembled structures like micelles of amphiphilic block copolymers, held by relatively weak physical interactions. Due to low stability of these polymolecular systems against dilution or temperature changes, different chemistry-based strategies to turn them into permanent nanopaticles were proposed in the literature (e.g., independent stabilization of a core or a shell of the micelles)

  12. PH-Sensitive Nanogels Synthesised by Radiation-Induced Cross-Linking of Hydrogen-Bonded Interpolymer Complexes in Aqueous Solution

    Energy Technology Data Exchange (ETDEWEB)

    Ulanski, P.; Kadłubowski, S.; Henke, A.; Olejnik, A. K.; Rokita, B.; Wach, R.; Rosiak, J.M., E-mail: slawekka@mitr.p.lodz.pl [Technical University of Lodz, Wroblewskiego 15, 93-590 Lodz (Poland)

    2010-07-01

    Nanogels, i.e., internally cross-linked hydrophilic polymeric particles of sub-micron sizes, gained much interest over the last years due to their possible application as components of advanced type of medicines, like drug carriers. It is expected that they can facilitate distribution and delivery of different types of biologically active substances (including proteins, peptides and oligonucleotides) in a controlled way within the human body. Nanogels and their bigger analogues – microgels, are mainly synthesised through free-radical cross-linking polymerization of monomers. This synthetic routine can be carried out in solution but more often emulsion techniques are preferred (mini- or microemulsion) due to easier size control and exclusion of the macrogelation process. Additionally, surfactant-free emulsion polymerization (SFEP) is the method of choice for the preparation of temperature-sensitive particles, mainly based on poly(N-isopropylacrylamide).Nanogels were also successfully prepared by intramolecular cross-linking of single macromolecules. More recently, covalent stabilization was utilized to obtain the self-assembled structures like micelles of amphiphilic block copolymers, held by relatively weak physical interactions. Due to low stability of these polymolecular systems against dilution or temperature changes, different chemistry-based strategies to turn them into permanent nanopaticles were proposed in the literature (e.g., independent stabilization of a core or a shell of the micelles)

  13. Adsorção de cromo (VI por carvão ativado granular de soluções diluídas utilizando um sistema batelada sob pH controlado Chromium (VI adsorption by GAC from diluted solutions in batch system and controlled ph

    Directory of Open Access Journals (Sweden)

    Renata Santos Souza

    2009-09-01

    solutions, and batch systems with controlled pH. The functional groups on the CAG surface was carried out by the Boehm method. In addition, effect of pH on the Cr(VI adsorption, adsorption equilibrium, and kinetic were studied under experimental conditions (pH = 6, MA = 6g, for 90min.. On the GAC surface, carboxylic groups were found to be in higher concentrations (MAS=0,43 mmol/gCAG, which increase the Cr(VI adsorption, principally in acidic pH values. The adsorption capacity is dependent on the pH of the solution, due to its influence on the surface properties of the CAG and different ionic forms of the Cr(VI solutions. The adsorption equilibrium data was adjusted satisfactorily by the Langmuir isotherm (R²=0,988, favorable type. From kinetics adsorption of 20 mg/L and 5 mg/L, the results were compatible with the national legislation (Res. nº 357/05. Therefore, the experimental system using (CAG was efficient in removing the Cr(VI from liquid streams containing low concentrations of the metal.

  14. Thermoelastic analysis of spent fuel and high level radioactive waste repositories in salt. A semi-analytical solution

    International Nuclear Information System (INIS)

    St John, C.M.

    1977-04-01

    An underground repository containing heat generating, High Level Waste or Spent Unreprocessed Fuel may be approximated as a finite number of heat sources distributed across the plane of the repository. The resulting temperature, displacement and stress changes may be calculated using analytical solutions, providing linear thermoelasticity is assumed. This report documents a computer program based on this approach and gives results that form the basis for a comparison between the effects of disposing of High Level Waste and Spent Unreprocessed Fuel

  15. Programmable pH buffers

    Science.gov (United States)

    Gough, Dara Van; Huber, Dale L.; Bunker, Bruce C.; Roberts, Mark E.

    2017-01-24

    A programmable pH buffer comprises a copolymer that changes pK.sub.a at a lower critical solution temperature (LCST) in water. The copolymer comprises a thermally programmable polymer that undergoes a hydrophobic-to-hydrophilic phase change at the LCST and an electrolytic polymer that exhibits acid-base properties that are responsive to the phase change. The programmable pH buffer can be used to sequester CO.sub.2 into water.

  16. A Two-Level Undercut-Profile Substrate for Chemical-Solution-Based Filamentary Coated Conductors

    DEFF Research Database (Denmark)

    Wulff, Anders Christian; Lundeman, Jesper H.; Hansen, Jørn B.

    2016-01-01

    . In the present study, the 2LUPS concept is applied to a commercial cube-textured Ni-5at.% W tape, and the surface of the 2LUPS coated with two Gd2Zr2O7 buffer layers using chemical solution deposition is examined. Except for narrow regions near the edge of upper plateaus, the plateaus are found to be covered...

  17. Chemically modified carbon paste electrode for fast screening of oxalic acid levels in soil solutions

    Czech Academy of Sciences Publication Activity Database

    Šestáková, Ivana; Jakl, M.; Jaklová Dytrtová, J.

    2008-01-01

    Roč. 102, - (2008), s. 140-140 E-ISSN 1213-7103. [International Conference on Electroanalysis /12./. 16.06.2008-19.06.2008, Prague] R&D Projects: GA ČR GA521/06/0496 Institutional research plan: CEZ:AV0Z40400503 Keywords : oxalic acid * carbon paste electrodes * soil solutions Subject RIV: CG - Electrochemistry

  18. Solutions for ecosystem-level protection of ocean systems under climate change

    NARCIS (Netherlands)

    Queirós, Ana M.; Huebert, Klaus B.; Keyl, Friedemann; Fernandes, Jose A.; Stolte, Willem; Maar, Marie; Kay, Susan; Jones, Miranda C.; Hamon, Katell G.; Hendriksen, Gerrit; Vermard, Youen; Marchal, Paul; Teal, Lorna R.; Somerfield, Paul J.; Austen, Melanie C.; Barange, Manuel; Sell, Anne F.; Allen, Icarus; Peck, Myron A.

    2016-01-01

    The Paris Conference of Parties (COP21) agreement renewed momentum for action against climate change, creating the space for solutions for conservation of the ocean addressing two of its largest threats: climate change and ocean
    acidification (CCOA). Recent arguments that ocean policies

  19. Remoção de metais pesados de efluentes aquosos pela zeólita natural escolecita - influência da temperatura e do pH na adsorção em sistemas monoelementares Heavy metals removal from wastewater by the natural zeolite scolecite - temperature and pH influence in single-metal solutions

    Directory of Open Access Journals (Sweden)

    Ricardo Sarti Jimenez

    2004-10-01

    Full Text Available Cation exchange capabilities of a Brazilian natural zeolite, identified as scolecite, were evaluated for application in wastewater control. We investigated the process of sorption of chromium(III, nickel(II, cadmium(II and manganese(II in synthetic aqueous effluents, including adsorption isotherms of single-metal solutions. The natural zeolite showed the ability to take up the tested heavy metals in the order Cr(III > Cd(II > Ni(II > Mn(II, and this could be related to the valence and the hydration radius of the metal cations. The influence of temperature (25, 40 and 60 ºC and initial pH value (from 4 to 6 was also evaluated. It was found that the adsorption increased substantially when the temperature was raised to 60 ºC and that maximum adsorption capacity was observed at pH 6. These results demonstrate that scolecite can be used for removal of heavy metals from aqueous effluents, under optimized conditions.

  20. Closed-form analytical solutions for assessing the consequences of sea-level rise on unconfined sloping island aquifers

    Science.gov (United States)

    Chesnaux, R.

    2016-04-01

    Closed-form analytical solutions for assessing the consequences of sea-level rise on fresh groundwater oceanic island lenses are provided for the cases of both strip and circular islands. Solutions are proposed for directly calculating the change in the thickness of the lens, the changes in volume and the changes in travel time of fresh groundwater within island aquifers. The solutions apply for homogenous aquifers recharged by surface infiltration and discharged by a down-gradient, fixed-head boundary. They also take into account the inland shift of the ocean due to land surface inundation, this shift being determined by the coastal slope of inland aquifers. The solutions are given for two simple island geometries: circular islands and strip islands. Base case examples are presented to illustrate, on one hand, the amplitude of the change of the fresh groundwater lens thickness and the volume depletion of the lens in oceanic island with sea-level rise, and on the other hand, the shortening of time required for groundwater to discharge into the ocean. These consequences can now be quantified and may help decision-makers to anticipate the effects of sea-level rise on fresh groundwater availability in oceanic island aquifers.

  1. Molecular dynamics investigation of ferrous-ferric electron transfer in a hydrolyzing aqueous solution: Calculation of the pH dependence of the diabatic transfer barrier and the potential of mean force

    International Nuclear Information System (INIS)

    Rustad, James R.; Rosso, Kevin M.; Felmy, Andrew R.

    2004-01-01

    We present a molecular model for ferrous-ferric electron transfer in an aqueous solution that accounts for electronic polarizability and exhibits spontaneous cation hydrolysis. An extended Lagrangian technique is introduced for carrying out calculations of electron-transfer barriers in polarizable systems. The model predicts that the diabatic barrier to electron transfer increases with increasing pH, due to stabilization of the Fe 3+ by fluctuations in the number of hydroxide ions in its first coordination sphere, in much the same way as the barrier would increase with increasing dielectric constant in the Marcus theory. We have also calculated the effect of pH on the potential of mean force between two hydrolyzing ions in aqueous solution. As expected, increasing pH reduces the potential of mean force between the ferrous and ferric ions in the model system. The magnitudes of the predicted increase in diabatic transfer barrier and the predicted decrease in the potential of mean force nearly cancel each other at the canonical transfer distance of 0.55 nm. Even though hydrolysis is allowed in our calculations, the distribution of reorganization energies has only one maximum and is Gaussian to an excellent approximation, giving a harmonic free energy surface in the reorganization energy F(ΔE) with a single minimum. There is thus a surprising amount of overlap in electron-transfer reorganization energies for Fe 2+ -Fe(H 2 O) 6 3+ , Fe 2+ -Fe(OH)(H 2 O) 5 2+ , and Fe 2+ -Fe(OH) 2 (H 2 O) + couples, indicating that fluctuations in hydrolysis state can be viewed on a continuum with other solvent contributions to the reorganization energy. There appears to be little justification for thinking of the transfer rate as arising from the contributions of different hydrolysis states. Electronic structure calculations indicate that Fe(H 2 O) 6 2+ -Fe(OH) n (H 2 O) 6-n (3-n)+ complexes interacting through H 3 O 2 - bridges do not have large electronic couplings

  2. A Low-Tech, Low-Budget Storage Solution for High Level Radioactive Sources

    Energy Technology Data Exchange (ETDEWEB)

    Brett Carlsen; Ted Reed; Todd Johnson; John Weathersby; Joe Alexander; Dave Griffith; Douglas Hamelin

    2014-07-01

    The need for safe, secure, and economical storage of radioactive material becomes increasingly important as beneficial uses of radioactive material expand (increases inventory), as political instability rises (increases threat), and as final disposal and treatment facilities are delayed (increases inventory and storage duration). Several vendor-produced storage casks are available for this purpose but are often costly — due to the required design, analyses, and licensing costs. Thus the relatively high costs of currently accepted storage solutions may inhibit substantial improvements in safety and security that might otherwise be achieved. This is particularly true in areas of the world where the economic and/or the regulatory infrastructure may not provide the means and/or the justification for such an expense. This paper considers a relatively low-cost, low-technology radioactive material storage solution. The basic concept consists of a simple shielded storage container that can be fabricated locally using a steel pipe and a corrugated steel culvert as forms enclosing a concrete annulus. Benefits of such a system include 1) a low-tech solution that utilizes materials and skills available virtually anywhere in the world, 2) a readily scalable design that easily adapts to specific needs such as the geometry and radioactivity of the source term material), 3) flexible placement allows for free-standing above-ground or in-ground (i.e., below grade or bermed) installation, 4) the ability for future relocation without direct handling of sources, and 5) a long operational lifetime . ‘Le mieux est l’ennemi du bien’ (translated: The best is the enemy of good) applies to the management of radioactive materials – particularly where the economic and/or regulatory justification for additional investment is lacking. Development of a low-cost alternative that considerably enhances safety and security may lead to a greater overall risk reduction than insisting on

  3. Chapter 6. Scaling Up Solutions to State, National and Global Levels

    OpenAIRE

    Kammen, Daniel; Rotman, Doug; Delmas, Magali; Feldman, David; Mielke, Mike; Ramesh, Ramamoorthy; Sperling, Daniel

    2016-01-01

    Scaling-up solutions require learning and adapting lessons between locations and at different scales. To accomplish this, common metrics are vital to building a shared language. For California, this has meant careful financial, cradle-to-grave life-cycle assessment methods leading to carbon accounting in many avenues of government (via the Low Carbon Fuel Standard or the Cap and Trade program). These methods themselves interact, such as the use of carbon accounting for the resources needed to...

  4. Students’ Learning Obstacles and Alternative Solution in Counting Rules Learning Levels Senior High School

    Directory of Open Access Journals (Sweden)

    M A Jatmiko

    2017-12-01

    Full Text Available The counting rules is a topic in mathematics senior high school. In the learning process, teachers often find students who have difficulties in learning this topic. Knowing the characteristics of students' learning difficulties and analyzing the causes is important for the teacher, as an effort in trying to reflect the learning process and as a reference in constructing alternative learning solutions which appropriate to anticipate students’ learning obstacles. This study uses qualitative methods and involves 70 students of class XII as research subjects. The data collection techniques used in this study is diagnostic test instrument about learning difficulties in counting rules, observation, and interview. The data used to know the learning difficulties experienced by students, the causes of learning difficulties, and to develop alternative learning solutions. From the results of data analysis, the results of diagnostic tests researcher found some obstacles faced by students, such as students get confused in describing the definition, students difficulties in understanding the procedure of solving multiplication rules. Based on those problems, researcher analyzed the causes of these difficulties and make hypothetical learning trajectory as an alternative solution in counting rules learning.

  5. Retrofitting solutions for two different occupancy levels of educational buildings in tropics

    Science.gov (United States)

    Yang, Junjing; Pantazaras, Alexandros; Lee, Siew Eang; Santamouris, Mattheos

    2018-01-01

    Within the multi-functionality of educational buildings, the energy conservation potential can be very different. In addition, among different retrofitting solutions investigated involving interventions on the building envelope, ventilation strategies, artificial lighting systems as well as equipment upgrading, different saving potential would come from different aspects. The opportunities for energy saving potential from the overall point of view and from the detailed aspect view of different retrofitting solutions would be very useful and important for building renovation decision making. This study presents a detailed retrofitting study of two different educational buildings. One represents a building with average occupancy variation and containing mainly offices and labs. The other one represents a building with high occupancy variation and containing mainly lecture rooms and studios. This comparison of the results gives an idea of the different energy saving potential for different types of educational buildings. Principal component analysis is also adopted to investigate the detailed performance of one of the buildings which is influenced stronger by these retrofitting solutions.

  6. The pH Game.

    Science.gov (United States)

    Chemecology, 1996

    1996-01-01

    Describes a game that can be used to teach students about the acidity of liquids and substances around their school and enable them to understand what pH levels tell us about the environment. Students collect samples and measure the pH of water, soil, plants, and other natural material. (DDR)

  7. Chapter 6. Scaling Up Solutions to State, National and Global Levels

    Directory of Open Access Journals (Sweden)

    Daniel Kammen

    2016-12-01

    Full Text Available Scaling-up solutions require learning and adapting lessons between locations and at different scales. To accomplish this, common metrics are vital to building a shared language. For California, this has meant careful financial, cradle-to-grave life-cycle assessment methods leading to carbon accounting in many avenues of government (via the Low Carbon Fuel Standard or the Cap and Trade program. These methods themselves interact, such as the use of carbon accounting for the resources needed to manage water and other key resources; the use of criteria air pollution monitoring to identify environmental injustices; and the use of carbon market revenues to address these inequalities, through investment in best available abatement technologies (BACT and in job creation in disadvantaged communities anticipated in the emerging clean energy sector.  Creating interdisciplinary partnerships across the UC Campuses and the National Laboratories to innovate science and technology is critical to scalable carbon neutrality solutions. As an example, we can build coordinated research and development programs across UC and California, with strong partnerships with the Federal government to coordinate and “multiply” resources that accelerate development and deployment. These partnerships should be strongly goal-focused, i.e., they are created to solve specific, large problems, to enable quantitatively measurable outcomes within energy generation, efficiency and CO2 abatement categories. Intersectoral partnerships should be fostered across campuses, laboratories, with state, federal and multi-lateral organizations funding to develop technologies and deploy solutions at scale. Integrated partnerships with industry are required to influence markets, deploy solutions, and create new industries and jobs.  Beyond California, we need to establish consortia with industry and foundations to deploy solutions at the regional, state, national, and international scale to

  8. Thousand Islands River : study of solutions to address critically low water levels : summary report; Riviere des Milles Iles : etude des solutions de soutien des etiages critiques : rapport sommaire

    Energy Technology Data Exchange (ETDEWEB)

    Cyr, J F; Fontin, M [Centre d' Expertise Hydrique du Quebec, Quebec, PQ (Canada). Service de la Securite des Barrages

    2005-07-01

    A study was conducted to find solutions to very low water flow in the Thousand Islands River, near the Island of Montreal, Quebec. It was launched in response to the critically low water levels that were experienced in 2001 and 2002. In the summer of 2001, municipalities served by the Thousand Island River were faced with problems in the supply of drinking water when the river flow reached approximately 13 cubic metres per second. Since 1970, the minimal values of flow observed for this time of year had seldom passed under 20 cubic metres per second. Under such conditions of flow, the dilution of any water discharged into the river became so weak that the aging water treatment facilities had to work beyond their capacity. In addition, the population served by this river has increased significantly in the past 2 decades. During this episode of critically low water levels, Quebec's Center of Water Expertise (CEHQ)intervened in an emergency measure to drain flows from a water reservoir in the catchment area to ensure a minimal flow of approximately 25 cubic metres per second. Thereafter, the affected municipalities had to ask the Quebec Environment Ministry to define permanent interventions to ensure a minimal flow the river in the event of similar episodes. The CEHQ carried out a preliminary study of possible solutions to address the critically low water levels and presented its report in the spring 2002. In the winter of 2002, CEHQ created an emergency management procedure in preparation of a repeat episode. 28 refs., 11 figs.

  9. Thousand Islands River : study of solutions to address critically low water levels : summary report; Riviere des Milles Iles : etude des solutions de soutien des etiages critiques : rapport sommaire

    Energy Technology Data Exchange (ETDEWEB)

    Cyr, J.F.; Fontin, M. [Centre d' Expertise Hydrique du Quebec, Quebec, PQ (Canada). Service de la Securite des Barrages

    2005-07-01

    A study was conducted to find solutions to very low water flow in the Thousand Islands River, near the Island of Montreal, Quebec. It was launched in response to the critically low water levels that were experienced in 2001 and 2002. In the summer of 2001, municipalities served by the Thousand Island River were faced with problems in the supply of drinking water when the river flow reached approximately 13 cubic metres per second. Since 1970, the minimal values of flow observed for this time of year had seldom passed under 20 cubic metres per second. Under such conditions of flow, the dilution of any water discharged into the river became so weak that the aging water treatment facilities had to work beyond their capacity. In addition, the population served by this river has increased significantly in the past 2 decades. During this episode of critically low water levels, Quebec's Center of Water Expertise (CEHQ)intervened in an emergency measure to drain flows from a water reservoir in the catchment area to ensure a minimal flow of approximately 25 cubic metres per second. Thereafter, the affected municipalities had to ask the Quebec Environment Ministry to define permanent interventions to ensure a minimal flow the river in the event of similar episodes. The CEHQ carried out a preliminary study of possible solutions to address the critically low water levels and presented its report in the spring 2002. In the winter of 2002, CEHQ created an emergency management procedure in preparation of a repeat episode. 28 refs., 11 figs.

  10. The effect of high pressure and residual oxygen on the color stability of minced cured restructured ham at different levels of drying, pH, and NaCl.

    Science.gov (United States)

    Bak, Kathrine Holmgaard; Lindahl, Gunilla; Karlsson, Anders H; Lloret, Elsa; Gou, Pere; Arnau, Jacint; Orlien, Vibeke

    2013-10-01

    Color stability of minced cured restructured ham was studied by considering the effects of high pressure (HP) (600 MPa, 13°C, 5 min), raw meat pH24 (low, normal, high), salt content (15, 30 g/kg), drying (20%, 50% weight loss), and residual oxygen level (0.02%-0.30%). Raw hams were selected by pH24 in Semimembranosus, mixed with additives, frozen, sliced, and dried by the Quick-Dry-Slice® (QDS) process followed by HP treatment or not (control). Packaging and storage simulated industrial packaging: modified atmosphere containing 80% N2, 20% CO2, and residual O2 in one of three intervals: hams, while the stabilizing effect on 50% QDS hams was smaller, concluding that water has the dominating role. Raw meat pH24, salt content, and residual oxygen level had varying effects on the stability of the red color. Copyright © 2013 Elsevier Ltd. All rights reserved.

  11. Modeling the chemical kinetics of atmospheric plasma for cell treatment in a liquid solution

    International Nuclear Information System (INIS)

    Kim, H. Y.; Kang, S. K.; Lee, H. Wk.; Lee, H. W.; Kim, G. C.; Lee, J. K.

    2012-01-01

    Low temperature atmospheric pressure plasmas have been known to be effective for living cell inactivation in a liquid solution but it is not clear yet which species are key factors for the cell treatment. Using a global model, we elucidate the processes through which pH level in the solution is changed from neutral to acidic after plasma exposure and key components with pH and air variation. First, pH level in a liquid solution is changed by He + and He(2 1 S) radicals. Second, O 3 density decreases as pH level in the solution decreases and air concentration decreases. It can be a method of removing O 3 that causes chest pain and damages lung tissue when the density is very high. H 2 O 2 , HO 2 , and NO radicals are found to be key factors for cell inactivation in the solution with pH and air variation.

  12. Neptunium separation in trace levels from uranium solutions by extraction chromatography

    International Nuclear Information System (INIS)

    Cotrim, M.B.; Matsuda, H.T.

    1994-01-01

    Neptunium and uranium behavior in extraction chromatograph system, aiming the separation of micro quantities of neptunium from uranyl solutions is described. Tri-n-octylamine (TOA), Tri-n-butylphosphate (TBP) as stationary phase, alumine, Voltalef UF-300 as support material were verified. The impregnation conditions as well as the best stationary phase/support material ratio were established. TBP/alumine, TBP/Voltalef and TOA/alumine system were selected to uranium and neptunium separation studies. (author) . 12 refs., 03 tabs., 03 figs

  13. TPACK Levels of Physics and Science Teacher Candidates: Problems and Possible Solutions

    Science.gov (United States)

    Bozkurt, Ersin

    2014-01-01

    This research examined whether the technological pedagogical content knowledge (TPACK) of physics and science teachers is at a sufficient level and whether the TPACK level affected the academic achievements of the students. In the research, a mixed method was used quantitatively and qualitatively. In the quantitative part of the research, Provus'…

  14. Evaluation of pH, buffering capacity, viscosity and flow rate levels of saliva in caries-free, minimal caries and nursing caries children: An in vivo study

    Directory of Open Access Journals (Sweden)

    Dwitha Animireddy

    2014-01-01

    Full Text Available Background and Aim: The present study was undertaken to evaluate the pH, buffering capacity, viscosity and flow rate of saliva in caries free, minimal caries and nursing caries children and to evaluate the relationship of these on the caries activity of children. Materials and Methods: A total of 75 school children of age group between 4 and 12 years were selected and divided into three equal groups: Group I, Group II and Group III, consisting of 25 subjects each. Group I included caries-free subjects, Group II included subjects with minimal caries and Group III included subjects with nursing caries. Saliva samples were collected from all subjects and were estimated for flow rate, pH, buffering capacity and viscosity. Results: There was a significant decrease in the mean salivary flow rate, salivary ph and salivary buffer capacity and a significant increase in the salivary viscosity among caries-free subjects, subjects with minimal caries and subjects with nursing caries. Conclusion: The physicochemical properties of saliva, such as salivary flow rate, pH, buffering capacity and viscosity, has a relation with caries activity in children and act as markers of caries activity.

  15. The Effect of Level of Information as Presented by Different Technologies on Students' Understanding of Acid, Base, and pH Concepts.

    Science.gov (United States)

    Nakhleh, Mary B.; Krajcik, Joseph S.

    Within high school chemistry the topic of acids, bases, and pH is particularly challenging because robust understanding of the topic depends heavily on the student possessing deep concepts of atoms, molecules, ions, and chemical reactions. Since knowledge is acquired and stored in a dynamic structure, it was investigated in this study how…

  16. Physiological functions at single-cell level of Lactobacillus spp. isolated from traditionally fermented cabbage in response to different pH conditions.

    Science.gov (United States)

    Olszewska, Magdalena A; Kocot, Aleksandra M; Łaniewska-Trokenheim, Łucja

    2015-04-20

    Changes in pH are significant environmental stresses that may be encountered by lactobacilli during fermentation processes or passage through the gastrointestinal tract. Here, we report the cell response of Lactobacillus spp. isolated from traditionally fermented cabbage subjected to acid/alkaline treatments at pH 2.5, 7.4 and 8.1, which represented pH conditions of the gastrointestinal tract. Among six isolates, four species of Lactobacillus plantarum and two of Lactobacillus brevis were identified by fluorescence in situ hybridization (FISH). The fluorescence-based strategy of combining carboxyfluorescein diacetate (CFDA) and propidium iodine (PI) into a dual-staining assay was used together with epifluorescence microscopy (EFM) and flow cytometry (FCM) for viability assessment. The results showed that the cells maintained esterase activity and membrane integrity at pH 8.1 and 7.4. There was also no loss of culturability as shown by plate counts. In contrast, the majority of 2.5 pH-treated cells had a low extent of esterase activity, and experienced membrane perturbation. For these samples, an extensive loss of culturability was demonstrated. Comparison of the results of an in situ assessment with that of the conventional culturing method has revealed that although part of the stressed population was unable to grow on the growth media, it was deemed viable using a CFDA/PI assay. However, there was no significant change in the cell morphology among pH-treated lactobacilli populations. These analyses are expected to be useful in understanding the cell response of Lactobacillus strains to pH stress and may facilitate future investigation into functional and industrial aspects of this response. Copyright © 2015 Elsevier B.V. All rights reserved.

  17. Sea level changes from monthly solutions of ice sheet mass balance

    DEFF Research Database (Denmark)

    Barletta, Valentina Roberta; Sørensen, Louise Sandberg; Forsberg, René

    We present mass change time series at basin scale for both Greenland and Antarctica, de-rived from GRACE data, and use these data to find the associated global sea level changes. We use two independent methods for GRACE ice mass loss estimation, including use of different GIA models and estimatio...

  18. From hierarchies to levels : new solutions for games with hierarchical structure

    NARCIS (Netherlands)

    Álvarez-Mozos, M.; van den Brink, R.; van der Laan, G.; Tejada, O.

    2017-01-01

    Recently, applications of cooperative game theory to economic allocation problems have gained popularity. In many of these problems, players are organized according to either a hierarchical structure or a levels structure that restrict the players’ possibilities to cooperate. In this paper, we

  19. Neptunium separation in trace levels from uranium solutions by extraction chromatography

    International Nuclear Information System (INIS)

    Figols, M.E.B.

    1991-01-01

    Neptunium and uranium behavior in extraction chromatography system, aiming the separation of microquantities of neptunium from uranyl nitrate solutions is described. Tri-n-octylamina (TOA), tri-n-butylphosphate (TBP), thenoyltrifluoroacetone (TTA) as stationary phase, alumina, Voltalef-UF-300, silica as support material were verified. The impregnation conditions as well as the best stationary phase/support material ratio were established. TBP/alumina, TBP/Voltalef and TOA/alumina system were selected to uranium and neptunium separation studies. In the system using TBP as extractant agent uranium and neptunium separation was reached by selective elution after the retention of both elements on the column. U-Np separation by selective retention of Np was possible with TOA system. The capacity of the column was the 66.6 mg U/mL and 191.6mg U/mL for the TBP/alumina and TBP/Voltalef systems, respectively. An application of extraction chromatography system in the final phase of irradiated uranium treatment process is proposed. (author)

  20. Asymptotically exact solution of the multi-channel resonant-level model

    International Nuclear Information System (INIS)

    Zhang Guangming; Su Zhaobin; Yu Lu.

    1994-01-01

    An asymptotically exact partition function of the multi-channel resonant-level model is obtained through Tomonaga-Luttinger bosonization. A Fermi-liquid vs. non-Fermi-liquid transition, resulting from a competition between the Kondo and X-ray edge physics, is elucidated explicitly via the renormalization group theory. In the strong-coupling limit, the model is renormalized to the Toulouse limit. (author). 20 refs, 1 fig

  1. Sterics level the rates of proton transfer to [Ni(XPh){PhP(CH₂CH₂PPh₂)₂}]⁺ (X = O, S or Se).

    Science.gov (United States)

    Alwaaly, Ahmed; Henderson, Richard A

    2014-09-04

    Rates of proton transfers between lutH(+) (lut = 2,6-dimethylpyridine) and [Ni(XPh)(PhP{CH2CH2PPh2}2)](+) (X = O, S or Se) are slow and show little variation (k(O) : k(S) : k(Se) = 1 : 12 : 9). This unusual behaviour is a consequence of sterics affecting the optimal interaction between the reactants prior to proton transfer.

  2. High pressure effect on the color of minced cured restructured ham at different levels of drying, pH, and NaCl.

    Science.gov (United States)

    Bak, Kathrine Holmgaard; Lindahl, Gunilla; Karlsson, Anders H; Lloret, Elsa; Ferrini, Gabriele; Arnau, Jacint; Orlien, Vibeke

    2012-03-01

    Color changes of minced cured restructured ham was studied considering the effects of high pressure (HP) treatment (600MPa, 13°C, 5min), raw meat pH(24) (low, normal, high), salt content (15, 30g/kg), and drying (20%, 50% weight loss). Raw hams were selected based on pH(24) in Semimembranosus, mixed with additives, frozen, sliced, and dried using the Quick-Dry-Slice® process. Meat color (CIE 1976 L*a*b*) and reflectance spectra were measured before and after HP treatment. HP significantly increased L*, decreased a*, and decreased b* for restructured ham dried to 20% weight loss, regardless of salt content and pH(24). L* and a* were best preserved in high pH/high salt restructured ham. HP had no effect on the color of restructured ham dried to 50% weight loss. HP had no effect on the shape of reflectance curves, indicating that the pigment responsible for minced cured restructured ham color did not change due to HP. Copyright © 2011 Elsevier Ltd. All rights reserved.

  3. Iodine evolution and pH control

    International Nuclear Information System (INIS)

    Beahm, E.C.; Lorenz, R.A.; Weber, C.F.

    1993-01-01

    The pH is the major factor in determining the extent of I 2 in solution. In containment where no pH-control chemicals are present, the acidity or basicity of the water pool will be determined by materials that are introduced into containment as a result of the accident itself. These materials may be fission products (i.e., cesium compounds), thermally produced products (i.e., core-concrete aerosols), or compounds produced by radiation (i.e., nitric acid). In situations where pH levels fall below ∼7, the formation of I 2 will occur in irradiated iodide solutions. A correlation between pH and iodine formation is needed so that the amounts I 2 in water pools can be assessed. This, in turn, determines the amount of I 2 in the atmosphere available for escape by containment leakage. A number of calculational routines based on more than 100 differential equations representing individual reactions can be found in the literature. In this work, it is shown that a simpler approach based on the steady-state decomposition of hydrogen peroxide should correctly describe iodine formation in severe accidents. Comparisons with test data show this approach to be valid. The most important acids in containment will be nitric acid (HNO 3 ), produced by irradiation of water and air, and hydrochloric acid (HCl), produced by irradiation or heating of electrical cable insulation. The most important bases in containment will be cesium hydroxide, cesium borate (or cesium carbonate), and in some plants pH additives, such as sodium hydroxide or sodium phosphate

  4. Evaluation of the electrochemical behavior of U2.5Zr7.5Nb and U3Zr9Nb uranium alloys in relation to the pH and the solution aeration

    International Nuclear Information System (INIS)

    Mansur, Fabio Abud; Santos, Ana Maria Matildes dos; Ferraz, Wilmar Barbosa; Figueiredo, Celia de Araujo

    2011-01-01

    The Centro de Desenvolvimento da Tecnologia Nuclear (CDTN) is developing, in cooperation with the Centro Tecnologico da Marinha (CTMSP), the advanced nuclear plate type fuel for the second core of the land-based reactor prototype of the Laboratorio de Geracao Nucleo-Eletrica (LABGENE). Recent investigations have shown that the fuel made of uranium-based niobium and zirconium alloys reaches the best performance relative to other fuels, e.g. UO 2 . Niobium and Zirconium also increase the corrosion resistance and the mechanical strength of the uranium alloys. By means of electrochemical techniques the corrosion behavior of alloys U 2 . 5 Zr 7.5 Nb and U 3 Zr 9 Nb, developed at CDTN and heat treated in the temperature range of 200 deg C to 600 deg C, was assessed. The effect of the parameters pH and solution aeration was studied as well as the influence of zirconium and niobium alloying elements in the corrosion of uranium. The techniques used were open circuit potential, electrochemical impedance and potentiodynamic anodic polarization at room temperature. The tests were performed in a three-electrode electrochemical cell with Ag/AgCl (3M KCl) as the reference electrode and a platinum plate as the auxiliary electrode. The potentiodynamic polarization curves of uranium and its alloys in acidic solutions showed regions with anodic currents limited by a passive film. The presence of niobium and zirconium contributed for the formation of this film. The impedance data showed the presence of two semicircles in the Bode diagram, indicating the occurrence of two distinct electrochemical processes. The data were fitted to an equivalent circuit model in order to obtain parameters of the electrochemical processes and evaluate the effect of the studied variables. (author)

  5. Removal of radium from aqueous sulphate solutions

    International Nuclear Information System (INIS)

    Weir, D.R.; Masters, J.T.; Neven, M.

    1983-01-01

    Radium is often present in ores and an aqueous solution associated with the ore may consequently contain dissolved radium. It is frequently necessary to remove radium from such solutions to reduce the total radium content to a prescribed low level before the solution can be returned to the environment. The present invention is based on the discovery that the total radium content can be reduced to a satisfactory level within a reasonable time by adding a soluble barium salt to a radium-containing sulphate solution which also contains dissolved magnesium at a pH not greater than about 0 to precipitate radium as barium radium sulphate, raising the pH to at least 11 to precipitate an insoluble magnesium compound which collects the barium radium sulphate precipitate, and separating substantially all of the precipitates from the solution

  6. Solutions to HYDROCOIN [Hydrologic Code Intercomparison] Level 1 problems using STOKES and PARTICLE (Cases 1,2,4,7)

    International Nuclear Information System (INIS)

    Gureghian, A.B.; Andrews, A.; Steidl, S.B.; Brandstetter, A.

    1987-10-01

    HYDROCOIN (Hydrologic Code Intercomparison) Level 1 benchmark problems are solved using the finite element ground-water flow code STOKES and the pathline generating code PARTICLE developed for the Office of Crystalline Repository Development (OCRD). The objective of the Level 1 benchmark problems is to verify the numerical accuracy of ground-water flow codes by intercomparison of their results with analytical solutions and other numerical computer codes. Seven test cases were proposed for Level 1 to the Swedish Nuclear Power Inspectorate, the managing participant of HYDROCOIN. Cases 1, 2, 4, and 7 were selected by OCRD because of their appropriateness to the nature of crystalline repository hydrologic performance. The background relevance, conceptual model, and assumptions of each case are presented. The governing equations, boundary conditions, input parameters, and the solution schemes applied to each case are discussed. The results are shown in graphic and tabular form with concluding remarks. The results demonstrate the two-dimensional verification of STOKES and PARTICLE. 5 refs., 61 figs., 30 tabs

  7. The disposal of high level radioactive wastes. Proposed solutions and uses in Brazil

    International Nuclear Information System (INIS)

    Toledo, J.F.A.

    1992-06-01

    The characteristics of high level radioactive waste produced in nuclear plants similar to that used in Brazil is presented. Subsequently it is described the international experience, and the way to apply such knowledge to the Brazilian situation, defining the magnitude of the problem, applying a methodology to select sites, and choosing areas for the location of a repository. Once such areas are defined, it is presented the behaviour of rock mass, similar to those found in the brazilian territory, based on the requirements for a high radioactive waste repository site. Finally, two Projects are presented for countries with lithologies similar to that of Brazil. The first one is choosing sites for a high radioactive waste repository program, and the second is an investigation of rock mass responses program. (author)

  8. Glasses used in the solidification of high level radioactive waste: their behaviour in aqueous solutions

    International Nuclear Information System (INIS)

    Grauer, R.

    1983-02-01

    Because of their amorphous structure, glasses are particularly suitable matrixes for the solidification of the mixture of radionuclides included in the high level wastes from reactor fuel reprocessing. They are not sensitive to variations in the fractions present of different waste oxides and are resistent to the effects of irradiation. In particular, borosilicate glasses have been investigated for around 25 years and the vitrification techniques have been tested on the technological scale. The environmental conditions within a final waste repository are expected to be such that the chemical resistance of glasses to attack by groundwaters is of special interest. In the present report the corrosion behaviour is described, with emphasis being placed upon the most significant controlling parameters. Since experimental determination of corrosion rates must be done in relatively short-time experiments, the results of which can depend strongly upon the measurement methods employed, it is necessary to carry out a critical assessment of the techniques commonly used in laboratory work. Experimental results are illustrated by means of selected examples. Particular emphasis is placed upon the effects of increased temperatures and of irradiation. The models which have been proposed for the estimation of the long-term corrosion behaviour of glasses are not yet fully sufficient and improvements are required. Furthermore, the actual corrosion rates which are fed into such models must be replaced by values more appropriate for the actual environmental conditions to which the glasses are most likely to be exposed within high level waste repositories. It should be noted, however, that even with current conservative input data on corrosion rates, typical estimated lifetimes for vitrified waste blocks are of the order of 10 5 years. The report concludes with recommendations concerning the most useful areas for further investigations. (author)

  9. Molecular Twister: A Game for Exploring Solution Chemistry †

    OpenAIRE

    Masonjones, Sawyer R.; Masonjones, Heather D.; Malone, Megan C.; Williams, Ann H.; Beemer, Margaret M.; Waggett, Rebecca J.

    2014-01-01

    pH is an essential biological concept with critical importance at various scales, from the molecular level, dealing with blood buffers, homeostasis, and proton gradients, all the way up to the ecosystem level, with soil chemistry and acid rain. However, pH is also a concept that spawns student misconceptions and misunderstanding in terms of what is happening in a solution on the atomic level. The Molecular Twister game, created for a Florida Department of Education funded professional develop...

  10. Spectroscopic determination of pH

    International Nuclear Information System (INIS)

    Faanu, A.; Glover, E.T.; Bailey, E.; Rochelle, C.

    2009-01-01

    A technique of measuring pH at temperature range of 20 - 70 0 C and high pressure conditions of 1 - 200 atmospheres has been developed by relating the ratio of absorbance peaks of indicator solutions (basic and acidic) as a function of pH, using ultraviolet-visible spectrophotometer. The pH values of the buffer solutions measured at 20 0 C and 70 0 C indicated slight temperature dependence, while the pressure had no effect. The pH of the buffer solutions increased with temperature with relative standard deviations in the range 0.4 - 0.5 % at 95 % confidence interval. The possible causes of the temperature dependence were attributed to changes in pH values as the temperature changed. (au)

  11. Muonated cyclohexadienyl radicals observed by level crossing resonance in dilute solutions of benzene in hexane subjected to muon-irradiation

    International Nuclear Information System (INIS)

    Walker, D.C.; Barnabas, M.V.; Venkateswaran, K.

    1988-11-01

    Benzene is used here as a scavenger of muonium to produce the muonated cyclohexadienyl radical in dilute solutions in n-hexane. The radical was identified by level crossing resonance spectroscopy (LCR) by observing the proton resonance of the -CHMu group occurring at 2.059T. Its yield is found to equal the sum of the muonium atom yield and the 'missing' muon yield in hexane (total 35% of the incident muons). Consequently, the complete dispersement of muons in different chemical associations is now accounted for in a saturated hydrocarbon liquid, and is seen to be similar to that in water

  12. Geologic disposal as optimal solution of managing the spent nuclear fuel and high-level radioactive waste

    International Nuclear Information System (INIS)

    Ilie, P.; Didita, L.; Ionescu, A.; Deaconu, V.

    2002-01-01

    To date there exist three alternatives for the concept of geological disposal: 1. storing the high-level waste (HLW) and spent nuclear fuel (SNF) on ground repositories; 2. solutions implying advanced separation processes including partitioning and transmutation (P and T) and eventual disposal in outer space; 3. geological disposal in repositories excavated in rocks. Ground storing seems to be advantageous as it ensures a secure sustainable storing system over many centuries (about 300 years). On the other hand ground storing would be only a postponement in decision making and will be eventually followed by geological disposal. Research in the P and T field is expected to entail a significant reduction of the amount of long-lived radioactive waste although the long term geological disposal will be not eliminated. Having in view the high cost, as well as the diversity of conditions in the countries owning power reactors it appears as a reasonable regional solution of HLW disposal that of sharing a common geological disposal. In Romania legislation concerning of radioactive waste is based on the Law concerning Spent Nuclear Fuel and Radioactive Waste Management in View of Final Disposal. One admits at present that for Romania geological disposal is not yet a stressing issue and hence intermediate ground storing of SNF will allow time for finding a better final solution

  13. Measurement of pH micro-heterogeneity in natural cheese matrices by fluorescence lifetime imaging

    OpenAIRE

    Zuzana eBurdikova; Zdenek eSvindrych; Jan ePala; Cian eHickey; Martin G. Wilkinson; Jiri ePanek; Mark A. E. Auty; Ammasi ePeriasamy; Jeremiah J. Sheehan

    2015-01-01

    Cheese, a product of microbial fermentation may be defined as a protein matrix entrapping fat, moisture, minerals and solutes as well as dispersed bacterial colonies. The growth and physiology of bacterial cells in these colonies may be influenced by the microenvironment around the colony, or alternatively the cells within the colony may modify the microenvironment (e.g., pH, redox potential) due to their metabolic activity. While cheese pH may be measured at macro level there remains a signi...

  14. Measurement of pH micro-heterogeneity in natural cheese matrices by flourescence lifetime imaging

    OpenAIRE

    Burdikova, Suzana; Svindrych, Zdenek; Pala, Jan; Hickey, Cian D; Wilkinson, Martin G.; Panek, Jiri; Auty, Mark A.E.; Periasamy, Ammasi; Sheehan, Jeremiah J.

    2015-01-01

    peer-reviewed Cheese, a product of microbial fermentation may be defined as a protein matrix entrapping fat, moisture, minerals and solutes as well as dispersed bacterial colonies. The growth and physiology of bacterial cells in these colonies may be influenced by the microenvironment around the colony, or alternatively the cells within the colony may modify the microenvironment (e.g., pH, redox potential) due to their metabolic activity. While cheese pH may be measured at macro level ther...

  15. Titratable acidity of beverages influences salivary pH recovery

    Directory of Open Access Journals (Sweden)

    Livia Maria Andaló TENUTA

    2015-01-01

    Full Text Available A low pH and a high titratable acidity of juices and cola-based beverages are relevant factors that contribute to dental erosion, but the relative importance of these properties to maintain salivary pH at demineralizing levels for long periods of time after drinking is unknown. In this crossover study conducted in vivo, orange juice, a cola-based soft drink, and a 10% sucrose solution (negative control were tested. These drinks differ in terms of their pH (3.5 ± 0.04, 2.5 ± 0.05, and 5.9 ± 0.1, respectively and titratable acidity (3.17 ± 0.06, 0.57 ± 0.04 and < 0.005 mmols OH- to reach pH 5.5, respectively. Eight volunteers with a normal salivary flow rate and buffering capacity kept 15 mL of each beverage in their mouth for 10 s, expectorated it, and their saliva was collected after 15, 30, 45, 60, 90, and 120 s. The salivary pH, determined using a mini pH electrode, returned to the baseline value at 30 s after expectoration of the cola-based soft drink, but only at 90 s after expectoration of the orange juice. The salivary pH increased to greater than 5.5 at 15 s after expectoration of the cola drink and at 30 s after expectoration of the orange juice. These findings suggest that the titratable acidity of a beverage influences salivary pH values after drinking acidic beverages more than the beverage pH.

  16. Titratable acidity of beverages influences salivary pH recovery.

    Science.gov (United States)

    Tenuta, Livia Maria Andaló; Fernández, Constanza Estefany; Brandão, Ana Carolina Siqueira; Cury, Jaime Aparecido

    2015-01-01

    A low pH and a high titratable acidity of juices and cola-based beverages are relevant factors that contribute to dental erosion, but the relative importance of these properties to maintain salivary pH at demineralizing levels for long periods of time after drinking is unknown. In this crossover study conducted in vivo, orange juice, a cola-based soft drink, and a 10% sucrose solution (negative control) were tested. These drinks differ in terms of their pH (3.5 ± 0.04, 2.5 ± 0.05, and 5.9 ± 0.1, respectively) and titratable acidity (3.17 ± 0.06, 0.57 ± 0.04 and pH 5.5, respectively). Eight volunteers with a normal salivary flow rate and buffering capacity kept 15 mL of each beverage in their mouth for 10 s, expectorated it, and their saliva was collected after 15, 30, 45, 60, 90, and 120 s. The salivary pH, determined using a mini pH electrode, returned to the baseline value at 30 s after expectoration of the cola-based soft drink, but only at 90 s after expectoration of the orange juice. The salivary pH increased to greater than 5.5 at 15 s after expectoration of the cola drink and at 30 s after expectoration of the orange juice. These findings suggest that the titratable acidity of a beverage influences salivary pH values after drinking acidic beverages more than the beverage pH.

  17. Challenge in manufacturing electrolyte solutions for lithium and lithium ion batteries quality control and minimizing contamination level

    Science.gov (United States)

    Heider, U.; Oesten, R.; Jungnitz, M.

    The quality of electrolytes for lithium batteries are a major topic in science and battery industries. The solvents and lithium salts should be of highest purity. Therefore, during preparation and handling of electrolyte solutions, the contamination level has to be minimized and the quality during packaging, storage and transportation has to be guaranteed. Especially, protic impurities are found to be very critical for LiPF 6-based electrolytes. The influence of water is reported to be tremendous. But also other protic impurities like alcohols are considered to play an important role in the electrolyte quality. The reaction of the protic impurities with LiPF 6 leads to the formation of HF which further reacts with cathode active materials (e.g., spinel) and the passivating films of the cathode and anode. For a better understanding of the protic impurities and their role in the electrolyte quality a systematic investigation of different impurities was carried out. Electrolytes were doped with different protic compounds. Then the electrolyte was analyzed for protic impurities and HF in dependence of time. First results showing the relation between protic impurities and HF are presented and discussed. In addition, different packaging materials for the electrolyte solutions were investigated. Storage tests were carried out at different temperatures and in different atmospheres. Results on contamination levels, influence of packaging, high temperature storage and handling are addressed.

  18. Stabilizing sodium hypochlorite at high pH: effects on soft tissue and dentin.

    Science.gov (United States)

    Jungbluth, Holger; Marending, Monika; De-Deus, Gustavo; Sener, Beatrice; Zehnder, Matthias

    2011-05-01

    When sodium hypochlorite solutions react with tissue, their pH drops and tissue sorption decreases. We studied whether stabilizing a NaOCl solution at a high pH would increase its soft-tissue dissolution capacity and effects on the dentin matrix compared with a standard NaOCl solution of the same concentration and similar initial pH. NaOCl solutions were prepared by mixing (1:1) a 10% stock solution with water (standard) or 2 mol/L NaOH (stabilized). Physiological saline and 1 mol/L NaOH served as the controls. Chlorine content and alkaline capacity of NaOCl solutions were determined. Standardized porcine palatal soft-tissue specimens and human root dentin bars were exposed to test and control solutions. Weight loss percentage was assessed in the soft-tissue dissolution assay. Three-point bending tests were performed on the root dentin bars to determine the modulus of elasticity and flexural strength. Values between groups were compared using one-way analysis of variance with the Bonferroni correction for multiple testing (α pH level of 7.5, respectively. The stabilized NaOCl dissolved significantly more soft tissue than the standard solution, and the pH remained high. It also caused a higher loss in elastic modulus and flexure strength (P < .05) than the control solutions, whereas the standard solution did not. NaOH-stabilized NaOCl solutions have a higher alkaline capacity and are thus more proteolytic than standard counterparts. Copyright © 2011 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

  19. Effect of pH on saturated hydraulic conductivity and soil dispersion

    Energy Technology Data Exchange (ETDEWEB)

    Suarez, D.L.; Roades, J.D.; Lavado, R.; Grieve, C.M.

    The adverse effects of exchangeable sodium on soil hydraulic conductivity (K) are well known, but at present only sodicity and total electrolyte concentration are used in evaluating irrigation water suitability. In arid areas, high sodicity is often associatd with high dissolved carbonate and thus high pH, but in humid areas high sodicity may be associated with low pH. To evaluate the effect of pH (as an independent variable) on K, solutions with the same SAR and electrolyte level were prepared at pH 6, 7, 8, and 9. Saturated K values were determined at constant flux in columns packed at a bulk density of 1.5 Mg m/sup -3/. At pH 9, saturated K values were lower than at pH 6 for a montmorillonitic and kaolinitic soil. For a vermiculitic soil with lower organic carbon and higher silt content, pH changes did not cause large K differences. Decreases in K were not reversible on application of waters with higher electrolyte levels. The results from the K experiments were generally consistent with optical transmission measurements of dispersion. Although anion adsorption was at or below detection limits and cation exchange capacity (CEC) was only slightly dependent on pH, differences in pH effects on K among soils are likely due to differences in quantities of variable-charge minerals and organic matter.

  20. Intracellular pH of Mycobacterium avium subsp. paratuberculosis following exposure to antimicrobial compounds monitored at the single cell level

    DEFF Research Database (Denmark)

    Gaggìa, Francesca; Nielsen, Dennis Sandris; Biavati, Bruno

    2010-01-01

    for 24h revealed the presence of a subpopulation of cells probably resistant to the antimicrobial compounds tested. Use of nisin and bacteriocin-producing LAB strains could lead to new intervention strategies for the control of MAP based on in vivo application of probiotic cultures as feed additives......Mycobacterium avium subsp. paratuberculosis (MAP) is the etiologic agent of Johne's disease; moreover, it seems to be implicated in the development of Crohn's disease in humans. In the present study, fluorescence ratio imaging microscopy (FRIM) was used to assess changes in intracellular pH (p......H(i)) of one strain of MAP after exposure to nisin and neutralized cell-free supernatants (NCSs) from five bacteriocin-producing lactic acid bacteria (LAB) with known probiotic properties. The evaluation of pH(i) by FRIM provides information about the physiological state of bacterial cells, bypassing the long...

  1. Precipitation of plutonium from acidic solutions using magnesium oxide

    International Nuclear Information System (INIS)

    Jones, S.A.

    1994-01-01

    Magnesium oxide will be used as a neutralizing agent for acidic plutonium-containing solutions. It is expected that as the magnesium oxide dissolves, the pH of the solution will rise, and plutonium will precipitate. The resulting solid will be tested for suitability to storage. The liquid is expected to contain plutonium levels that meet disposal limit requirements

  2. Multi-level Quantum Mechanics and Molecular Mechanics Study of Ring Opening Process of Guanine Damage by Hydroxyl Radical in Aqueous Solution.

    Science.gov (United States)

    Liu, Peng; Wang, Qiong; Niu, Meixing; Wang, Dunyou

    2017-08-10

    Combining multi-level quantum mechanics theories and molecular mechanics with an explicit water model, we investigated the ring opening process of guanine damage by hydroxyl radical in aqueous solution. The detailed, atomic-level ring-opening mechanism along the reaction pathway was revealed in aqueous solution at the CCSD(T)/MM levels of theory. The potentials of mean force in aqueous solution were calculated at both the DFT/MM and CCSD(T)/MM levels of the theory. Our study found that the aqueous solution has a significant effect on this reaction in solution. In particular, by comparing the geometries of the stationary points between in gas phase and in aqueous solution, we found that the aqueous solution has a tremendous impact on the torsion angles much more than on the bond lengths and bending angles. Our calculated free-energy barrier height 31.6 kcal/mol at the CCSD(T)/MM level of theory agrees well with the one obtained based on gas-phase reaction profile and free energies of solvation. In addition, the reaction path in gas phase was also mapped using multi-level quantum mechanics theories, which shows a reaction barrier at 19.2 kcal/mol at the CCSD(T) level of theory, agreeing very well with a recent ab initio calculation result at 20.8 kcal/mol.

  3. A ph sensor based on a flexible substrate

    Science.gov (United States)

    Huang, Wen-Ding

    pH sensor is an essential component used in many chemical, food, and bio-material industries. Conventional glass electrodes have been used to construct pH sensors, however, have some disadvantages. Glass electrodes are easily affected by alkaline or HF solution, they require a high input impedance pH meter, they often exhibit a sluggish response. In some specific applications, it is also difficult to use glass electrodes for in vivo biomedical or food monitoring applications due to the difficulty of size miniaturization, planarization and polymerization based on current manufacturing technologies. In this work, we have demonstrated a novel flexible pH sensor based on low-cost sol-gel fabrication process of iridium oxide (IrOx) sensing film (IROF). A pair of flexible miniature IrOx/AgCl electrode generated the action potential from the solution by electrochemical mechanism to obtain the pH level of the reagent. The fabrication process including sol-gel, thermal oxidation, and the electro-plating process of the silver chloride (AgCl) reference electrode were reported in the work. The IrOx film was verified and characterized using electron dispersive analysis (EDAX), scanning electron microscope (SEM), and x-ray diffraction (XRD). The flexible pH sensor's performance and characterization have been investigated with different testing parameters such as sensitivity, response time, stability, reversibility, repeatability, selectivity and temperature dependence. The flexible IrOx pH sensors exhibited promising sensing performance with a near-Nernstian response of sensitivity which is between --51.1mV/pH and --51.7mV/pH in different pH levels ranging from 1.5 to 12 at 25°C. Two applications including gastroesophageal reflux disease (GERD) diagnosis and food freshness wireless monitoring using our micro-flexible IrOx pH sensors were demonstrated. For the GERD diagnosing system, we embedded the micro flexible pH sensor on a 1.2cmx3.8cm of the capsule size of wireless sensor

  4. Early containment of high-alkaline solution simulating low-level radioactive waste stream in clay-bearing blended cement

    International Nuclear Information System (INIS)

    Kruger, A.A.; Olson, R.A.; Tennis, P.D.

    1995-04-01

    Portland cement blended with fly ash and attapulgite clay was mixed with high-alkaline solution simulating low-level radioactive waste stream at a one-to-one weight ratio. Mixtures were adiabatically and isothermally cured at various temperatures and analyzed for phase composition, total alkalinity, pore solution chemistry, and transport properties as measured by impedance spectroscopy. Total alkalinity is characterized by two main drops. The early one corresponds to a rapid removal of phosphorous, aluminum, sodium, and to a lesser extent potassium solution. The second drop from about 10 h to 3 days is mainly associated with the removal of aluminum, silicon, and sodium. Thereafter, the total alkalinity continues descending, but at a lower rate. All pastes display a rapid flow loss that is attributed to an early precipitation of hydrated products. Hemicarbonate appears as early as one hour after mixing and is probably followed by apatite precipitation. However, the former is unstable and decomposes at a rate that is inversely related to the curing temperature. At high temperatures, zeolite appears at about 10 h after mixing. At 30 days, the stabilized crystalline composition Includes zeolite, apatite and other minor amounts of CaCO 3 , quartz, and monosulfate Impedance spectra conform with the chemical and mineralogical data. The normalized conductivity of the pastes shows an early drop, which is followed by a main decrease from about 12 h to three days. At three days, the permeability of the cement-based waste as calculated by Katz-Thompson equation is over three orders of magnitude lower than that of ordinary portland cement paste. However, a further decrease in the calculated permeability is questionable. Chemical stabilization is favorable through incorporation of waste species into apatite and zeolite

  5. Changes of organic acid exudation and rhizosphere pH in rice plants under chromium stress

    International Nuclear Information System (INIS)

    Zeng Fanrong; Chen Song; Miao Ying; Wu Feibo; Zhang Guoping

    2008-01-01

    The effect of chromium (Cr) stress on the changes of rhizosphere pH, organic acid exudation, and Cr accumulation in plants was studied using two rice genotypes differing in grain Cr accumulation. The results showed that rhizosphere pH increased with increasing level of Cr in the culture solution and with an extended time of Cr exposure. Among the six organic acids examined in this experiment, oxalic and malic acid contents were relatively higher, and had a significant positive correlation with the rhizosphere pH, indicating that they play an important role in changing rhizosphere pH. The Cr content in roots was significantly higher than that in stems and leaves. Cr accumulation in plants was significantly and positively correlated with rhizosphere pH, and the exudation of oxalic, malic and citric acids, suggesting that an increase in rhizosphere pH, and exudation of oxalic, malic and citric acid enhances Cr accumulation in rice plants. - Rhizosphere pH and organic acid exudation of rice roots are markedly affected by chromium level in culture solution

  6. Ikaite crystals in melting sea ice – implications for pCO2 and pH levels in Arctic surface waters

    DEFF Research Database (Denmark)

    Rysgaard, Søren; Glud, R.N.; Lennert, K.

    2012-01-01

    A major issue of Arctic marine science is to understand whether the Arctic Ocean is, or will be, a source or sink for air-sea CO 2 exchange. This has been complicated by the recent discoveries of ikaite (a polymorph of CaCO 3•6H 2O) in Arctic and Antarctic sea ice, which indicate that multiple...... chemical transformations occur in sea ice with a possible effect on CO 2 and pH conditions in surface waters. Here, we report on biogeochemical conditions, microscopic examinations and x-ray diffraction analysis of single crystals from a melting 1.7 km 2 (0.5-1 m thick) drifting ice floe in the Fram Strait...... during summer. Our findings show that ikaite crystals are present throughout the sea ice but with larger crystals appearing in the upper ice layers. Ikaite crystals placed at elevated temperatures disintegrated into smaller crystallites and dissolved. During our field campaign in late June, melt reduced...

  7. Influence of pH on extracellular matrix preservation during lung decellularization.

    Science.gov (United States)

    Tsuchiya, Tomoshi; Balestrini, Jenna L; Mendez, Julio; Calle, Elizabeth A; Zhao, Liping; Niklason, Laura E

    2014-12-01

    The creation of decellularized organs for use in regenerative medicine requires the preservation of the organ extracellular matrix (ECM) as a means to provide critical cues for differentiation and migration of cells that are seeded onto the organ scaffold. The purpose of this study was to assess the influence of varying pH levels on the preservation of key ECM components during the decellularization of rat lungs. Herein, we show that the pH of the 3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonate (CHAPS)-based decellularization solution influences ECM retention, cell removal, and also the potential for host response upon implantation of acellular lung tissue. The preservation of ECM components, including elastin, fibronectin, and laminin, were better retained in the lower pH conditions that were tested (pH ranges tested: 8, 10, 12); glycosaminoglycans were preserved to a higher extent in the lower pH groups as well. The DNA content following decellularization of the rat lung was inversely correlated with the pH of the decellularization solution. Despite detectible levels of cyotoskeletal proteins and significant residual DNA, tissues decellularized at pH 8 demonstrated the greatest tissue architecture maintenance and the least induction of host response of all acellular conditions. These results highlight the effect of pH on the results obtained by organ decellularization and suggest that altering the pH of the solutions used for decellularization may influence the ability of cells to properly differentiate and home to appropriate locations within the scaffold, based on the preservation of key ECM components and implantation results.

  8. Method of continuously regenerating decontaminating electrolytic solution

    International Nuclear Information System (INIS)

    Sasaki, Takashi; Kobayashi, Toshio; Wada, Koichi.

    1985-01-01

    Purpose: To continuously recover radioactive metal ions from the electrolytic solution used for the electrolytic decontamination of radioactive equipment and increased with the radioactive dose, as well as regenerate the electrolytic solution to a high concentration acid. Method: A liquid in an auxiliary tank is recycled to a cathode chamber containing water of an electro depositing regeneration tank to render pH = 2 by way of a pH controller and a pH electrode. The electrolytic solution in an electrolytic decontaminating tank is introduced by way of an injection pump to an auxiliary tank and, interlocking therewith, a regenerating solution is introduced from a regenerating solution extracting pump by way of a extraction pipeway to an electrolytic decontaminating tank. Meanwhile, electric current is supplied to the electrode to deposit radioactive metal ions dissolved in the cathode chamber on the capturing electrode. While on the other hand, anions are transferred by way of a partition wall to an anode chamber to regenerate the electrolytic solution to high concentration acid solution. While on the other hand, water is supplied by way of an electromagnetic valve interlocking with the level meter to maintain the level meter constant. This can decrease the generation of the liquid wastes and also reduce the amount of the radioactive secondary wastes. (Horiuchi, T.)

  9. Characterization of the Vaginal Microbiota of Ewes and Cows Reveals a Unique Microbiota with Low Levels of Lactobacilli and Near-Neutral pH

    Science.gov (United States)

    Swartz, Jeffrey D.; Lachman, Medora; Westveer, Kelsey; O’Neill, Thomas; Geary, Thomas; Kott, Rodney W.; Berardinelli, James G.; Hatfield, Patrick G.; Thomson, Jennifer M.; Roberts, Andy; Yeoman, Carl J.

    2014-01-01

    Although a number of common reproductive disorders in livestock involve bacterial infection, very little is known about their normal vaginal microbiota. Therefore, we sought to determine the species composition of sheep and cattle vaginal microbiota. Twenty Rambouillet ewes and twenty crossbred cows varying in age and reproductive status were sampled by ectocervicovaginal lavage. We amplified and sequenced the V3–V4 region of the 16S ribosomal RNA (rRNA) contents yielding a total of 907,667 high-quality reads. Good’s Coverage estimates indicated that we obtained data on 98 ± 0.01% of the total microbial genera present in each sample. Cow and ewe vaginal microbiota displayed few differences. Cow microbiota exhibited greater (P ≤ 0.05) α-diversity compared to the ewe microbiota. Both livestock species differed (P ≤ 0.05) from all previously reported vaginal communities. While bacteria were numerically dominant, Archaea were detected in 95% of cow and ewe samples, mainly of the order Desulfurococcales. Both ewes and cows were predominately colonized by the bacterial phyla Bacteroidetes, Fusobacteria, and Proteobacteria. The most abundant genera were Aggregatibacter spp., and Streptobacillus spp. Lactobacillus spp. were detected in 80% of ewe and 90% of cow samples, but only at very low abundances. Bacteria previously described from culture-based studies as common to the cow and ewe vaginal tract, except for Escherichia, were variably present, and only in low abundance. Ewe and cow pH differed (P ≤ 0.05), with means (±SD) of 6.7 ± 0.38 and 7.3 ± 0.63, respectively. In conclusion, 16S rRNA sequencing of cow and ewe vaginal ectocervicovaginal lavages showed that cow and ewe vaginal microbiota differ from culture-led results, revealing a microbiota distinct from previously described vaginal ecosystems. PMID:26664918

  10. Ikaite crystals in melting sea ice - implications for pCO2 and pH levels in Arctic surface waters

    Science.gov (United States)

    Rysgaard, S.; Glud, R. N.; Lennert, K.; Cooper, M.; Halden, N.; Leakey, R. J. G.; Hawthorne, F. C.; Barber, D.

    2012-08-01

    A major issue of Arctic marine science is to understand whether the Arctic Ocean is, or will be, a source or sink for air-sea CO2 exchange. This has been complicated by the recent discoveries of ikaite (a polymorph of CaCO3·6H2O) in Arctic and Antarctic sea ice, which indicate that multiple chemical transformations occur in sea ice with a possible effect on CO2 and pH conditions in surface waters. Here, we report on biogeochemical conditions, microscopic examinations and x-ray diffraction analysis of single crystals from a melting 1.7 km2 (0.5-1 m thick) drifting ice floe in the Fram Strait during summer. Our findings show that ikaite crystals are present throughout the sea ice but with larger crystals appearing in the upper ice layers. Ikaite crystals placed at elevated temperatures disintegrated into smaller crystallites and dissolved. During our field campaign in late June, melt reduced the ice floe thickness by 0.2 m per week and resulted in an estimated 3.8 ppm decrease of pCO2 in the ocean surface mixed layer. This corresponds to an air-sea CO2 uptake of 10.6 mmol m-2 sea ice d-1 or to 3.3 ton km-2 ice floe week-1. This is markedly higher than the estimated primary production within the ice floe of 0.3-1.3 mmol m-2 sea ice d-1. Finally, the presence of ikaite in sea ice and the dissolution of the mineral during melting of the sea ice and mixing of the melt water into the surface oceanic mixed layer accounted for half of the estimated pCO2 uptake.

  11. Ikaite crystals in melting sea ice – implications for pCO2 and pH levels in Arctic surface waters

    Directory of Open Access Journals (Sweden)

    R. J. G. Leakey

    2012-08-01

    Full Text Available A major issue of Arctic marine science is to understand whether the Arctic Ocean is, or will be, a source or sink for air–sea CO2 exchange. This has been complicated by the recent discoveries of ikaite (a polymorph of CaCO3·6H2O in Arctic and Antarctic sea ice, which indicate that multiple chemical transformations occur in sea ice with a possible effect on CO2 and pH conditions in surface waters. Here, we report on biogeochemical conditions, microscopic examinations and x-ray diffraction analysis of single crystals from a melting 1.7 km2 (0.5–1 m thick drifting ice floe in the Fram Strait during summer. Our findings show that ikaite crystals are present throughout the sea ice but with larger crystals appearing in the upper ice layers. Ikaite crystals placed at elevated temperatures disintegrated into smaller crystallites and dissolved. During our field campaign in late June, melt reduced the ice floe thickness by 0.2 m per week and resulted in an estimated 3.8 ppm decrease of pCO2 in the ocean surface mixed layer. This corresponds to an air–sea CO2 uptake of 10.6 mmol m−2 sea ice d−1 or to 3.3 ton km−2 ice floe week−1. This is markedly higher than the estimated primary production within the ice floe of 0.3–1.3 mmol m−2 sea ice d−1. Finally, the presence of ikaite in sea ice and the dissolution of the mineral during melting of the sea ice and mixing of the melt water into the surface oceanic mixed layer accounted for half of the estimated pCO2 uptake.

  12. Transport of a solute pulse through the bentonite barrier of deep geological high-level waste storage facilities in granite

    International Nuclear Information System (INIS)

    Cormenzana Lopez, J.L.; Alonso Diaz-Teran, J.; Gonzalez- Herranz, E.

    1997-01-01

    Spain like Sweden, Finland, Canada and other countries has opted for an open nuclear fuel cycle, and to store the unreprocessed spent fuel in a stable geological formation. Sweden, Finland and Canada have chosen granite rock for their high-level waste storage facilities. Their Performance Assessment of disposal systems have all obtained to the same result. The greatest annual doses are caused by I 129 in the gap between the fuel rods and the cladding. The reference concept for the Spanish high-level waste storage facility in granite provides for final storage in a granite mass at a depth of 500 m in carbon steel capsules in horizontal tunnels surrounded by a bentonite buffer. It the capsule fails due to generalised corrosion, an not giving credit for the cladding, the I 129 and other radionuclides in the gap would pass immediately into the surrounding water. This paper describes the modelling of the transport of the solute through the bentonite around the capsule to determine the fraction that crosses the bentonite each year. It also analyses the sensitivity of the results to the boundary condition adopted and changes in the values of the relevant parameters. (Author)

  13. The pH-static enzyme sensor: design of the pH control system

    NARCIS (Netherlands)

    van der Schoot, B.H.; van der Schoot, Bart H.; Voorthuijzen, Hans; Voorthuyzen, J.A.; Bergveld, Piet

    1990-01-01

    The pH-static enzyme sensor offers a solution to the buffer dependency of ISFET-based enzyme sensors. A continuous coulometric titration of the reaction products keeps the pH in the enzymatic membrane at a constant level. This paper presents an automatic system to control the compensating current

  14. Milles Iles River : study of solutions to address critically low water levels; Riviere des Milles Iles : etude des solutions de soutien des etiages critiques

    Energy Technology Data Exchange (ETDEWEB)

    Cyr, J F; Fontin, M [Centre d' Expertise Hydrique du Quebec, Quebec, PQ (Canada). Service de la Securite des Barrages

    2006-07-01

    Water management for the Mille Iles River, which supplies drinking water to 400,000 people, was discussed with reference to solutions for critically low water flow which was experienced in 2001 and 2002. The river is part of the Lac des Deux Montagnes watershed in the region of Montreal which is characterized as a high population growth area. In the summer of 2001, municipalities served by the Mille Iles River were faced with problems in the supply of drinking water when the river flow reached only 13 cubic metres per second. The minimal values of flow observed for this time of year have rarely been under 20 cubic metres per second since 1970. The quality of water was reduced under such conditions of flow because the dilution of wastewater discharged into the river became so weak that the aging water treatment facilities had to work beyond their capacity. Quebec's Center of Water Expertise (CEHQ) intervened in an emergency measure to ensure water quality. This study investigated the following 3 possible scenarios for a solution to this problem: (1) to increase the Mille Iles River capacity at the Lac des Deux Montagnes outlet, (2) to reduce the flow discharged by the 3 other outlets of Lac des Deux Montagnes, and (3) to increase the inflow to Lac des Deux Montagnes from reservoirs located in the Ottawa River watershed. The first solution was favoured. 2 refs., 1 tab., 8 figs.

  15. Milles Iles River : study of solutions to address critically low water levels; Riviere des Milles Iles : etude des solutions de soutien des etiages critiques

    Energy Technology Data Exchange (ETDEWEB)

    Cyr, J.F.; Fontin, M. [Centre d' Expertise Hydrique du Quebec, Quebec, PQ (Canada). Service de la Securite des Barrages

    2006-07-01

    Water management for the Mille Iles River, which supplies drinking water to 400,000 people, was discussed with reference to solutions for critically low water flow which was experienced in 2001 and 2002. The river is part of the Lac des Deux Montagnes watershed in the region of Montreal which is characterized as a high population growth area. In the summer of 2001, municipalities served by the Mille Iles River were faced with problems in the supply of drinking water when the river flow reached only 13 cubic metres per second. The minimal values of flow observed for this time of year have rarely been under 20 cubic metres per second since 1970. The quality of water was reduced under such conditions of flow because the dilution of wastewater discharged into the river became so weak that the aging water treatment facilities had to work beyond their capacity. Quebec's Center of Water Expertise (CEHQ) intervened in an emergency measure to ensure water quality. This study investigated the following 3 possible scenarios for a solution to this problem: (1) to increase the Mille Iles River capacity at the Lac des Deux Montagnes outlet, (2) to reduce the flow discharged by the 3 other outlets of Lac des Deux Montagnes, and (3) to increase the inflow to Lac des Deux Montagnes from reservoirs located in the Ottawa River watershed. The first solution was favoured. 2 refs., 1 tab., 8 figs.

  16. Electrical Conductivity and Chemical Composition of Soil Solution: Comparison of Solution Samplers in Tropical Soils

    Directory of Open Access Journals (Sweden)

    Davi Lopes do Carmo

    2016-01-01

    Full Text Available ABSTRACT Soil solution samplers may have the same working principle, but they differ in relation to chemical and physical characteristics, cost and handling, and these aspects exert influence on the chemical composition of the soil solution obtained. This study was carried out to evaluate, over time, the chemical composition of solutions extracted by Suolo Acqua, with the hydrophilic membrane (HM as a standard, using soils with contrasting characteristics, and to determine the relationship between electrical conductivity (EC and concentration of ions and pH of soil solution samples. This study was carried out under laboratory conditions, using three soils samples with different clay and organic matter (OM contents. Soil solution contents of F−, Cl−, NO−3, Br−, SO42−, Na+, NH4+, K+, Mg2+, Ca2+, were analyzed, as well as inorganic, organic, and total C contents, pH, and EC, in four successive sampling times. Soil solution chemical composition extracted by the Suolo Acqua sampler is similar to that collected by the HM, but the Suolo Acqua extracted more Na+ and soluble organic C than the HM solution. Solution EC, cation and anion concentrations, and soluble C levels are higher in the soil with greater clay and OM contents (Latossolo and Cambissolo in this case. Soil solution composition varied over time, with considerable changes in pH, EC, and nutrient concentrations, especially associated with soil OM. Thus, single and isolated sampling of the soil solution must be avoided, otherwise composition of the soil solution may not be correctly evaluated. Soil solution EC was regulated by pH, as well as the sum of cation and anion concentrations, and the C contents determined in the soil liquid phase.

  17. Using mineralogy and higher-level taxonomy as indicators of species sensitivity to pH: A case-study of Puget Sound

    Directory of Open Access Journals (Sweden)

    Shallin Busch

    2017-09-01

    Full Text Available Information on ecosystem sensitivity to global change can help guide management decisions. Here, we characterize the sensitivity of the Puget Sound ecosystem to ocean acidification by estimating, at a number of taxonomic levels, the direct sensitivity of its species. We compare sensitivity estimates based on species mineralogy and on published literature from laboratory experiments and field studies. We generated information on the former by building a database of species in Puget Sound with mineralogy estimates for all CaCO3-forming species. For the latter, we relied on a recently developed database and meta-analysis on temperate species responses to increased CO2. In general, species sensitivity estimates based on the published literature suggest that calcifying species are more sensitive to increased CO2 than non-calcifying species. However, this generalization is incomplete, as non-calcifying species also show direct sensitivity to high CO2 conditions. We did not find a strong link between mineral solubility and the sensitivity of species survival to changes in carbonate chemistry, suggesting that, at coarse scales, mineralogy plays a lesser role to other physiological sensitivities. Summarizing species sensitivity at the family level resulted in higher sensitivity scalar scores than at the class level, suggesting that grouping results at the class level may overestimate species sensitivity. This result raises caution about the use of broad generalizations on species response to ocean acidification, particularly when developing summary information for specific locations. While we have much to learn about species response to ocean acidification and how to generalize ecosystem response, this study on Puget Sound suggests that detailed information on species performance under elevated carbon dioxide conditions, summarized at the lowest taxonomic level possible, is more valuable than information on species mineralogy.

  18. Reaction of H atoms with chelators in highly basic solution: H2 production in high level liquid waste simulants

    International Nuclear Information System (INIS)

    Barnabas, F.; Cerny, E.; Jonah, C.D.; Meisel, D.; Sauer, M.C. Jr.

    1995-01-01

    The rate constants for hydrogen abstraction by H from ethylene-diamine tetracetic acid (EDTA), N-(2-hydroxyethyl)-ethylenediaminetriacetic acid (HEDTA), nitrilotriacetic acid (NTA), iminodiacetic acid (IDA), glycolic acid and citric acid were measured at pH 13. The predominant product of these reactions is H 2 . The rate constants obtained are more than an order of magnitude larger than the literature rates that had been measured at pH 1. These measurements are of significance for understanding the radiolytic production of H 2 in nuclear waste storage tanks. (Author)

  19. Dissolution of Simulated and Radioactive Savannah River Site High-Level Waste Sludges with Oxalic Acid & Citric Acid Solutions

    International Nuclear Information System (INIS)

    STALLINGS, MARY

    2004-01-01

    sludge solids. We recommend that these results be evaluated further to determine if these solutions contain sufficient neutron poisons. We observed low general corrosion rates in tests in which carbon steel coupons were contacted with solutions of oxalic acid, citric acid and mixtures of oxalic and citric acids. Wall thinning can be minimized by maintaining short contact times with these acid solutions. We recommend additional testing with oxalic and oxalic/citric acid mixtures to measure dissolution performance of sludges that have not been previously dried. This testing should include tests to clearly ascertain the effects of total acid strength and metal complexation on dissolution performance. Further work should also evaluate the downstream impacts of citric acid on the SRS High-Level Waste System (e.g., radiochemical separations in the Salt Waste Processing Facility and addition of organic carbon in the Saltstone and Defense Waste Processing facilities)

  20. Method for producing rapid pH changes

    Science.gov (United States)

    Clark, J.H.; Campillo, A.J.; Shapiro, S.L.; Winn, K.R.

    A method of initiating a rapid pH change in a solution comprises irradiating the solution with an intense flux of electromagnetic radiation of a frequency which produces a substantial pK change to a compound in solution. To optimize the resulting pH change, the compound being irradiated in solution should have an excited state lifetime substantially longer than the time required to establish an excited state acid-base equilibrium in the solution. Desired pH changes can be accomplished in nanoseconds or less by means of picosecond pulses of laser radiation.

  1. Technetium-99 levels in pertechnetate solutions from (n,γ) and (n,f) molybdenum-99 generators

    International Nuclear Information System (INIS)

    Moore, P.W.

    1983-04-01

    There is increasing evidence that, in some radiopharmaceutical kits, Tc-99 has an adverse effect on the imaging and labelling performance of Tc-99m. For example, labelling efficiency with red blood cells can be affected when 99/99m ratios exceed about 4:1. The 99/99m ratio in a target is about 13.5:1 after a seven-day irradiation in a nuclear reactor. The ratio increases slightly during the time needed for processing. With the chromatographic generators used in hospitals, up to 90 hours may elapse between the final wash stage of manufacture and the first elution, during which time, 99/99m ratios can increase to about 90:1. If elution efficiencies are high and the time between elutions is between 12 and 24 hours, ratios in the generator, hence in the eluates, may actually increase with each elution. In the case of ready-to-inject pertechnetate solutions, the critical time at which 99/99m ratios increase rapidly is the time between elution and use. If production conditions are poor, ratios may increase to more than 600:1 by the time of use. With better conditions and production schedules Tc-99 levels at the time of use are comparable to those from chromatographic generators

  2. Acid Rain, pH & Acidity: A Common Misinterpretation.

    Science.gov (United States)

    Clark, David B.; Thompson, Ronald E.

    1989-01-01

    Illustrates the basis for misleading statements about the relationship between pH and acid content in acid rain. Explains why pH cannot be used as a measure of acidity for rain or any other solution. Suggests that teachers present acidity and pH as two separate and distinct concepts. (RT)

  3. Plasma glucose level in elective surgical patients administered with 5% dextrose in 0.45% NaCl in comparison with those receiving lactated Ringer's solution.

    Science.gov (United States)

    Saringcarinkul, Ananchanok; Kotrawera, Kriengsak

    2009-09-01

    To determine the effect of dextrose containing solution (5% dextrose in 0.45% NaCl) compared to non-dextrose containing solution (lactated Ringer's solution) on plasma glucose level in elective surgical patients. A prospective randomized double-blind control trial was conducted on 60 patients aged 18-60, with ASA physical status I to II, who were scheduled for elective surgery at Maharaj Nakorn Chiang Mai Hospital, Thailand between October; 2007 and September; 2008. The patients received either lactated Ringer's solution (Group L), or 5% dextrose in 0.45% NaCl (Group D) in the morning of the operation day. Blood glucose levels were determined before intravenous fluid administration (T0), at the beginning (T1), after the 1st hr (T2), and at the end of surgery (T3). Mean duration of preoperative fast was almost 11 hrs in both groups; however, none of the patients had preoperative hypoglycemia. The blood sugar levels were significantly higher in the patients receiving 5% dextrose solution compared to the patients receiving lactated Ringer's solution at the beginning, after the 1st hr and at the end of surgery (p-value = 0.06, 0.018 and 0.036 respectively). There were some patients having hyperglycemia after receiving 5% dextrose in 0.45% NaCl during surgery. However, none of the average plasma glucose values in either group was considered as hyperglycemia. Though they fasted many hours before surgery, no patients were found to have hypoglycemia. The large volume of lactate Ringer's solution had minimal effect on the blood sugar levels compared to the levels in 5% dextrose in 0.45% NaCl group. Therefore, lactate Ringer's solution is probably the alternative choice of intravenous fluid for perioperative maintenance and can be used as replacement in healthy patients undergoing elective surgery.

  4. pH in atomic scale simulations of electrochemical interfaces

    DEFF Research Database (Denmark)

    Rossmeisl, Jan; Chan, Karen; Ahmed, Rizwan

    2013-01-01

    Electrochemical reaction rates can strongly depend on pH, and there is increasing interest in electrocatalysis in alkaline solution. To date, no method has been devised to address pH in atomic scale simulations. We present a simple method to determine the atomic structure of the metal......|solution interface at a given pH and electrode potential. Using Pt(111)|water as an example, we show the effect of pH on the interfacial structure, and discuss its impact on reaction energies and barriers. This method paves the way for ab initio studies of pH effects on the structure and electrocatalytic activity...

  5. ph Sensitive hydrogel as colon specific drug delivery

    International Nuclear Information System (INIS)

    Alarifi, A.S.

    2011-01-01

    γ-radiation induced graft copolymerization and crosslinking was for the synthesis of ph-sensitive hydrogels composed of poly (vinyl pyrrolidone) acrylic acid. The prepared hydrogels were subjected to swelling test to evaluate the effects of ph and ionic strength of the surrounding solution. Drastic changes in the swelling parameters where observed by changing the surrounding solution ph values. The release of ibuprofen from hydrogels was monitored as a function of time at ph 1 and ph 7 in order to evaluate the prepared copolymer ability for colon- specific drug carrier uses.

  6. Corrosion of zirconium alloys in alternating pH environment

    International Nuclear Information System (INIS)

    Mayer, P.; Manolescu, A.V.

    1985-01-01

    Behaviour of two commercial alloys, Zircaloy-2 and zirconium-2.5 wt% niobium were investigated in an environment of alternating pH. Corrosion advancement and scale morphology of coupons exposed to aqueous solution of LiOH (pH 10.2 and 14) were followed as a function of temperature (300-360 degreesC) and time (up to 165 days). The test sequence consisted of short term exposure to high pH and re-exposure to low pH solutions for extended period of time followed by a short term test in high pH. The results of these tests and detailed post-corrosion analysis indicate a fundamental difference between the corrosion behaviour of these two materials. Both alloys corrode fast in high pH environments, but only zirconium-2.5 wt% niobium continues to form detectable new oxide in low pH solution

  7. Ratiometric pH Imaging with a CoII2 MRI Probe via CEST Effects of Opposing pH Dependences (Postprint)

    Science.gov (United States)

    2017-10-13

    acid-catalyzed proton exchange, respectively. Importantly, the pH calibration curve is independent of the probe concentration and is identical in...in aqueous solutions containing 50 mM HEPES and 100 mM NaCl buffered at various pH values were acquired using D2O in an inner capillary to lock the...ppm using a presaturation pulse applied for 6 s at a power level (B1) of 24 μT. D2O was placed in an inner capillary within the NMR sample tube to lock

  8. Measurement of pH micro-heterogeneity in natural cheese matrices by fluorescence lifetime imaging

    Directory of Open Access Journals (Sweden)

    Zuzana eBurdikova

    2015-03-01

    Full Text Available Cheese, a product of microbial fermentation may be defined as a protein matrix entrapping fat, moisture, minerals and solutes as well as dispersed bacterial colonies. The growth and physiology of bacterial cells in these colonies may be influenced by the microenvironment around the colony, or alternatively the cells within the colony may modify the microenvironment (e.g. pH, redox potential due to their metabolic activity. While cheese pH may be measured at macro level there remains a significant knowledge gap relating to the degree of micro-heterogeneity of pH within the cheese matrix and its relationship with microbial, enzymatic and physiochemical parameters and ultimately with cheese quality, consistency and ripening patterns. The pH of cheese samples was monitored both at macroscopic scale and at microscopic scale, using a non-destructive microscopic technique employing C-SNARF-4 and Oregon Green 488 fluorescent probes. The objectives of this work were to evaluate the suitability of these dyes for microscale pH measurements in natural cheese matrices and to enhance the sensitivity and extend the useful pH range of these probes using fluorescence lifetime imaging (FLIM. In particular, fluorescence lifetime of Oregon Green 488 proved to be sensitive probe to map pH micro heterogeneity within cheese matrices. Good agreement was observed between macroscopic scale pH measurement by FLIM and by traditional pH methods, but in addition considerable localized microheterogeneity in pH was evident within the curd matrix with pH range between 4.0 and 5.5. This technique provides significant potential to further investigate the relationship between cheese matrix physico-chemistry and bacterial metabolism during cheese manufacture and ripening.

  9. Measurement of pH micro-heterogeneity in natural cheese matrices by fluorescence lifetime imaging.

    Science.gov (United States)

    Burdikova, Zuzana; Svindrych, Zdenek; Pala, Jan; Hickey, Cian D; Wilkinson, Martin G; Panek, Jiri; Auty, Mark A E; Periasamy, Ammasi; Sheehan, Jeremiah J

    2015-01-01

    Cheese, a product of microbial fermentation may be defined as a protein matrix entrapping fat, moisture, minerals and solutes as well as dispersed bacterial colonies. The growth and physiology of bacterial cells in these colonies may be influenced by the microenvironment around the colony, or alternatively the cells within the colony may modify the microenvironment (e.g., pH, redox potential) due to their metabolic activity. While cheese pH may be measured at macro level there remains a significant knowledge gap relating to the degree of micro-heterogeneity of pH within the cheese matrix and its relationship with microbial, enzymatic and physiochemical parameters and ultimately with cheese quality, consistency and ripening patterns. The pH of cheese samples was monitored both at macroscopic scale and at microscopic scale, using a non-destructive microscopic technique employing C-SNARF-4 and Oregon Green 488 fluorescent probes. The objectives of this work were to evaluate the suitability of these dyes for microscale pH measurements in natural cheese matrices and to enhance the sensitivity and extend the useful pH range of these probes using fluorescence lifetime imaging (FLIM). In particular, fluorescence lifetime of Oregon Green 488 proved to be sensitive probe to map pH micro heterogeneity within cheese matrices. Good agreement was observed between macroscopic scale pH measurement by FLIM and by traditional pH methods, but in addition considerable localized microheterogeneity in pH was evident within the curd matrix with pH range between 4.0 and 5.5. This technique provides significant potential to further investigate the relationship between cheese matrix physico-chemistry and bacterial metabolism during cheese manufacture and ripening.

  10. Technetium recovery from high alkaline solution

    Energy Technology Data Exchange (ETDEWEB)

    Nash, Charles A.

    2016-07-12

    Disclosed are methods for recovering technetium from a highly alkaline solution. The highly alkaline solution can be a liquid waste solution from a nuclear waste processing system. Methods can include combining the solution with a reductant capable of reducing technetium at the high pH of the solution and adding to or forming in the solution an adsorbent capable of adsorbing the precipitated technetium at the high pH of the solution.

  11. Effect of use of socially marketed faucet fitted earthen vessel/sodium hypochlorite solution on diarrhea prevention at household level in rural India

    Directory of Open Access Journals (Sweden)

    AR Dongre

    2008-07-01

    Full Text Available Objective: To evaluate the effect of socially marketed faucet fitted to earthen vessel / sodium hypochlorite solution on diarrhea prevention at rural household level as a social intervention for diarrhea prevention under ‘Community Led Initiatives for Child Survival (CLICS program. Methods: Unmatched case-control study was carried out in 10 villages of Primary Health Centre, Anji, located in rural central India. During the study period, 144 households used either faucet fitted earthen vessel to store drinking water or used sodium hypochlorite solution (SH for keeping drinking water safe. These served as case households for the present study. 213 neighborhood control households from same locality who used neither of the methods were also selected. Results: Odds ratio for households who used faucets fitted to earthen vessel was 0.49 (95% CI= 0.25 – 0.95. Odds ratio for households who used sodium hypochlorite solution was 0.55 (95% CI= 0.31 – 0.98. Use of these methods by the community, would prevent about 27 percent and 22 percent cases of the diarrhea (Population attributable risk proportion = 0.25 by faucets fitted to earthen vessels and 0.22 by use of sodium hypochlorite solution respectively. Conclusion: To ensure safe drinking water at household level, the effective and cheap methods like fitting faucet to traditionally used earthen vessel and/or use of sodium hypochlorite solution must be promoted through community participation at household level for cost and culture sensitive rural people in India.

  12. Sugar-based gemini surfactant with a vesicle-to-micelle transition at acidic pH and a reversible vesicle flocculation near neutral pH

    NARCIS (Netherlands)

    Johnsson, M; Wagenaar, A; Engberts, JBFN

    2003-01-01

    A sugar-based (reduced glucose) gemini surfactant forms vesicles in dilute aqueous solution near neutral pH. At lower pH, there is a vesicle-to-micelle transition within a narrow pH region (pH 6.0-5.6). The vesicles are transformed into large cylindrical micelles that in turn are transformed into

  13. SWCNT-Based Biosensor Modelling for pH Detection

    Directory of Open Access Journals (Sweden)

    Mohammad Javad Kiani

    2015-01-01

    Full Text Available Different forms of CNT delivery have been discovered with several biomedical functions during past decades. The mechanisms of the cellular uptake of CNTs are mainly maintained due to the chemical nature, the cell type, and the features of the molecules, which are used to functionalize the nanotube exterior. Since single-wall carbon Nanotube (SWCNT has unique chemical and physical properties, it is a great applicant for pH sensing. In addition, ion sensitive FET (ISFET base on nanostructured SWCNT have covered a new method to help genetic investigators restructure metabolic pathways in cells, recognize the progression of disease, and expand diagnostics and therapeutics. Particularly, because PH sensing is very crucial for the constancy of enzymes, it is essential to extend the cost efficient types of this sensing. In this research, the conductance changes of the CNT-based ISFET device with different pH values can be modelled by ion concentration of the solution. In addition, the electrical current of channel is imagined as a function of pH levels, which can be controlled by a control factor (α. Thus, ISFET based nanostructured SWCNT is proposed focusing on the area of electrical detection of hydrogen ions of the electrolyte membrane. Besides, electrical detection of hydrogen ion applications is suggested to be used by modelling the delivery of SWCNT sheets. In the end, after comparing the proposed model and experimental data, it has been reported that there is a good compatibility between them.

  14. Multi-level quantum mechanics theories and molecular mechanics study of the double-inversion mechanism of the F- + CH3I reaction in aqueous solution.

    Science.gov (United States)

    Liu, Peng; Zhang, Jingxue; Wang, Dunyou

    2017-06-07

    A double-inversion mechanism of the F - + CH 3 I reaction was discovered in aqueous solution using combined multi-level quantum mechanics theories and molecular mechanics. The stationary points along the reaction path show very different structures to the ones in the gas phase due to the interactions between the solvent and solute, especially strong hydrogen bonds. An intermediate complex, a minimum on the potential of mean force, was found to serve as a connecting-link between the abstraction-induced inversion transition state and the Walden-inversion transition state. The potentials of mean force were calculated with both the DFT/MM and CCSD(T)/MM levels of theory. Our calculated free energy barrier of the abstraction-induced inversion is 69.5 kcal mol -1 at the CCSD(T)/MM level of theory, which agrees with the one at 72.9 kcal mol -1 calculated using the Born solvation model and gas-phase data; and our calculated free energy barrier of the Walden inversion is 24.2 kcal mol -1 , which agrees very well with the experimental value at 25.2 kcal mol -1 in aqueous solution. The calculations show that the aqueous solution makes significant contributions to the potentials of mean force and exerts a big impact on the molecular-level evolution along the reaction pathway.

  15. PH og modernismen

    DEFF Research Database (Denmark)

    Ahnfeldt-Mollerup, Merete

    2012-01-01

    Artiklen kaster et kritisk blik på Poul Henningsens samfundsanalyse og dennes sammenhæng med hans design. PH ses i en bredere national og international sammenhæng. Diskussion af designmetoder, æstetik og Bauhaus.......Artiklen kaster et kritisk blik på Poul Henningsens samfundsanalyse og dennes sammenhæng med hans design. PH ses i en bredere national og international sammenhæng. Diskussion af designmetoder, æstetik og Bauhaus....

  16. Steering urban environmental quality in a multi-level governance context. How can devolution be the solution to pollution?

    NARCIS (Netherlands)

    Stigt, van Rien; Driessen, Peter P.J.; Spit, Tejo

    2016-01-01

    Devolution is advocated as a solution to scale mismatches in urban environmental governance. However, urban environmental quality is a multi-scalar issue: its various aspects – noise, soil, odour, air, water et cetera – are influenced by processes at multiple spatial and temporal scales. Decisions

  17. HYDROCOIN [HYDROlogic COde INtercomparison] Level 1: Benchmarking and verification test results with CFEST [Coupled Fluid, Energy, and Solute Transport] code: Draft report

    International Nuclear Information System (INIS)

    Yabusaki, S.; Cole, C.; Monti, A.M.; Gupta, S.K.

    1987-04-01

    Part of the safety analysis is evaluating groundwater flow through the repository and the host rock to the accessible environment by developing mathematical or analytical models and numerical computer codes describing the flow mechanisms. This need led to the establishment of an international project called HYDROCOIN (HYDROlogic COde INtercomparison) organized by the Swedish Nuclear Power Inspectorate, a forum for discussing techniques and strategies in subsurface hydrologic modeling. The major objective of the present effort, HYDROCOIN Level 1, is determining the numerical accuracy of the computer codes. The definition of each case includes the input parameters, the governing equations, the output specifications, and the format. The Coupled Fluid, Energy, and Solute Transport (CFEST) code was applied to solve cases 1, 2, 4, 5, and 7; the Finite Element Three-Dimensional Groundwater (FE3DGW) Flow Model was used to solve case 6. Case 3 has been ignored because unsaturated flow is not pertinent to SRP. This report presents the Level 1 results furnished by the project teams. The numerical accuracy of the codes is determined by (1) comparing the computational results with analytical solutions for cases that have analytical solutions (namely cases 1 and 4), and (2) intercomparing results from codes for cases which do not have analytical solutions (cases 2, 5, 6, and 7). Cases 1, 2, 6, and 7 relate to flow analyses, whereas cases 4 and 5 require nonlinear solutions. 7 refs., 71 figs., 9 tabs

  18. A Simple Technique for Determining the pH of Whole Cigarette Smoke

    Directory of Open Access Journals (Sweden)

    Dong J

    2014-12-01

    Full Text Available A new technique has been developed to determine the pH of whole cigarette smoke. In this technique, whole smoke from ten cigarettes was trapped in 300 mL water containing 1% (w/v sodium chloride and the pH was determined on the resulting aqueous suspension of cigarette smoke. Two impingers with an extra coarse porosity fritted disc were used to dispense the smoke in the aqueous trapping medium. Cigarettes were smoked on a 20-port Borgwaldt RM 20/CS smoking machine using modified FTC (Federal Trade Commission conditions. The puff volume was adjusted to take a 35 mL puff as measured through the cigarette and the collection traps. This new technique accounts for the contributions to smoke pH from both the vapor phase and the particulate phase of smoke. The repeatability of this new technique was determined on eighteen replicates of a commercially available non-menthol, filter cigarette. Each measurement was done on a different day to check for a possible drift in pH with time. The mean pH value for the chosen sample was found to be 4.97 with a standard deviation of 0.07 pH units. The smoke pH values for over 150 commercially available cigarette brands with a variety of “tar” levels were determined. The smoke pH values had a range from 4.6 to 5.5, with an average of 4.79 and a maximum standard deviation of 0.10 pH units. An experimental flue cured cigarette had a smoke pH of around 5.0, while an experimental Burley cigarette had a smoke pH of 5.4. No correlation between smoke pH and “tar” or total particulate matter (TPM and between pH and nicotine levels was found. The purpose of the present study was to develop a practical, relatively simple laboratory method to measure the pH of a water solution of whole smoke, and was not intended to reflect, or have direct relevance for any biochemical or biological phenomena such as inhalability of smoke, flavor perception, nicotine ab-sorption, etc.”

  19. The influence of calcium and pH on growth in primary roots of Zea mays

    Science.gov (United States)

    Hasenstein, K. H.; Evans, M. L.

    1988-01-01

    We investigated the interaction of Ca2+ and pH on root elongation in Zea mays L. cv. B73 x Missouri 17 and cv. Merit. Seedlings were raised to contain high levels of Ca2+ (HC, imbibed and raised in 10 mM CaCl2) or low levels of Ca2+ (LC, imbibed and raised in distilled water). In HC roots, lowering the pH (5 mM MES/Tris) from 6.5 to 4.5 resulted in strong, long-lasting growth promotion. Surprisingly, increasing the pH from 6.5 to 8.5 also resulted in strong growth promotion. In LC roots acidification of the medium (pH 6.5 to 4.5) resulted in transient growth stimulation followed by a gradual decline in the growth rate toward zero. Exposure of LC roots to high pH (pH shift from 6.5 to 8.5) also promoted growth. Addition of EGTA resulted in strong growth promotion in both LC and HC roots. The ability of EGTA to stimulate growth appeared not to be related to H+ release from EGTA upon Ca2+ chelation since, 1) LC roots showed a strong and prolonged response to EGTA, but only a transient response to acid pH, and 2) promotion of growth by EGTA was observed in strongly buffered solutions. We also examined the pH dependence of the release of 45Ca2+ from roots of 3-day-old seedlings grown from grains imbibed in 45Ca2+. Release of 45Ca2+ from the root into agar blocks placed on the root surface was greater the more acidic the pH of the blocks. The results indicate that Ca2+ may be necessary for the acid growth response in roots.

  20. Physiological indexese macro- and micronutrients in plant tissue and essential oil of Mentha piperita L. grown in nutrient solution with variation in N, P, K and Mg levels

    Directory of Open Access Journals (Sweden)

    E.F.S. David

    2014-03-01

    Full Text Available Mentha piperita L. is an aromatic and medicinal species of the family Lamiaceae, known as mint or peppermint, and its leaves and branches produce essential oil rich in menthol. This study aimed to evaluate physiological indexes, macro- and micronutrients inthe shootsand essential oil of Mentha piperita L. grown in nutrient solution number 2 of Hoagland and Arnon (1950 with different N, P, K and Mg levels. Shoot length, dry mass of the different organs, total dry mass, leaf area, essential oil yield and composition, and macronutrient (N, P, K, Mg, Ca, S and micronutrient (Mn, Cu, Fe, Zn contents in the shoot were evaluated. Plants treated with 65%N/50%P/25%K/100%Mg had a tendency towards longer shoot, greaterroot and leaf blade dry masses, higher essential oil yield, higher menthol levels and lower menthone levels. The results showed that Mentha can be grown in nutrient solution by reducing 65% N, 50% P, 25% K and 100% Mg. This solution had better development compared to the other tested treatments. Therefore,we recommendMentha piperita L. to be grown with such nutrient levels.

  1. Optimisation of liquid scintillation counting conditions to determine low activity levels of tritium and radiostrontium in aqueous solution

    Energy Technology Data Exchange (ETDEWEB)

    Rauret, Gemma; Mestres, J.S.; Ribera, Merce; Rajadel, Pilar (Barcelona Univ. (Spain). Dept. de Quimica Analitica)

    1990-08-01

    An optimisation of the counting conditions for the measurement of aqueous solutions of tritium or radiostrontium using Insta-Gel II as scintillator is presented. The variables optimised were the window, the ratio of mass of sample to mass of scintillator and the total volume of the counting mixture. An optimisation function which takes into account each of these variables, the background and also the efficiency is proposed. The conditions established allow the lowest possible detection limit to be reached. For tritium, this value was compared with that obtained when the standard method for water analysis was applied. (author).

  2. The role of the national low level waste repository operator in delivering new solutions for the management of low level wastes in the UK - 16217

    International Nuclear Information System (INIS)

    Walkingshaw, Martin

    2009-01-01

    The UK National Low Level Waste Repository (LLWR) is located near to the village of Drigg in West Cumbria. It is the principal site for disposal of solid Low Level Radioactive Waste (LLW) in the United Kingdom. This paper describes the program of work currently being undertaken by the site's operators, (LLW Repository Ltd and its newly appointed Parent Body Organisation), to extend the life of the LLWR and reduce the overall cost of LLW management to the UK taxpayer. The current focus of this program is to prevent disposal capacity being taken up at LLWR by waste types which lend themselves to alternative treatment and/or disposition routes. The chosen approach enables consignors to segregate LLW at source into formats which allow further treatment for volume reduction or, (for wastes with lower levels of activity), consignment in the future to alternative disposal facilities. Segregated waste services are incorporated into LLW Disposal commercial agreements between the LLWR operator and waste consignors. (author)

  3. Regulating NETosis: Increasing pH Promotes NADPH Oxidase-Dependent NETosis

    Science.gov (United States)

    Khan, Meraj A.; Philip, Lijy M.; Cheung, Guillaume; Vadakepeedika, Shawn; Grasemann, Hartmut; Sweezey, Neil; Palaniyar, Nades

    2018-01-01

    Neutrophils migrating from the blood (pH 7.35–7.45) into the surrounding tissues encounter changes in extracellular pH (pHe) conditions. Upon activation of NADPH oxidase 2 (Nox), neutrophils generate large amounts of H+ ions reducing the intracellular pH (pHi). Nevertheless, how extracellular pH regulates neutrophil extracellular trap (NET) formation (NETosis) is not clearly established. We hypothesized that increasing pH increases Nox-mediated production of reactive oxygen species (ROS) and neutrophil protease activity, stimulating NETosis. Here, we found that raising pHe (ranging from 6.6 to 7.8; every 0.2 units) increased pHi of both activated and resting neutrophils within 10–20 min (Seminaphtharhodafluor dual fluorescence measurements). Since Nox activity generates H+ ions, pHi is lower in neutrophils that are activated compared to resting. We also found that higher pH stimulated Nox-dependent ROS production (R123 generation; flow cytometry, plate reader assay, and imaging) during spontaneous and phorbol myristate acetate-induced NETosis (Sytox Green assays, immunoconfocal microscopy, and quantifying NETs). In neutrophils that are activated and not resting, higher pH stimulated histone H4 cleavage (Western blots) and NETosis. Raising pH increased Escherichia coli lipopolysaccharide-, Pseudomonas aeruginosa (Gram-negative)-, and Staphylococcus aureus (Gram-positive)-induced NETosis. Thus, higher pHe promoted Nox-dependent ROS production, protease activity, and NETosis; lower pH has the opposite effect. These studies provided mechanistic steps of pHe-mediated regulation of Nox-dependent NETosis. Raising pH either by sodium bicarbonate or Tris base (clinically known as Tris hydroxymethyl aminomethane, tromethamine, or THAM) increases NETosis. Each Tris molecule can bind 3H+ ions, whereas each bicarbonate HCO3− ion binds 1H+ ion. Therefore, the amount of Tris solution required to cause the same increase in pH level is less than that of equimolar

  4. Regulating NETosis: Increasing pH Promotes NADPH Oxidase-Dependent NETosis

    Directory of Open Access Journals (Sweden)

    Meraj A. Khan

    2018-02-01

    Full Text Available Neutrophils migrating from the blood (pH 7.35–7.45 into the surrounding tissues encounter changes in extracellular pH (pHe conditions. Upon activation of NADPH oxidase 2 (Nox, neutrophils generate large amounts of H+ ions reducing the intracellular pH (pHi. Nevertheless, how extracellular pH regulates neutrophil extracellular trap (NET formation (NETosis is not clearly established. We hypothesized that increasing pH increases Nox-mediated production of reactive oxygen species (ROS and neutrophil protease activity, stimulating NETosis. Here, we found that raising pHe (ranging from 6.6 to 7.8; every 0.2 units increased pHi of both activated and resting neutrophils within 10–20 min (Seminaphtharhodafluor dual fluorescence measurements. Since Nox activity generates H+ ions, pHi is lower in neutrophils that are activated compared to resting. We also found that higher pH stimulated Nox-dependent ROS production (R123 generation; flow cytometry, plate reader assay, and imaging during spontaneous and phorbol myristate acetate-induced NETosis (Sytox Green assays, immunoconfocal microscopy, and quantifying NETs. In neutrophils that are activated and not resting, higher pH stimulated histone H4 cleavage (Western blots and NETosis. Raising pH increased Escherichia coli lipopolysaccharide-, Pseudomonas aeruginosa (Gram-negative-, and Staphylococcus aureus (Gram-positive-induced NETosis. Thus, higher pHe promoted Nox-dependent ROS production, protease activity, and NETosis; lower pH has the opposite effect. These studies provided mechanistic steps of pHe-mediated regulation of Nox-dependent NETosis. Raising pH either by sodium bicarbonate or Tris base (clinically known as Tris hydroxymethyl aminomethane, tromethamine, or THAM increases NETosis. Each Tris molecule can bind 3H+ ions, whereas each bicarbonate HCO3− ion binds 1H+ ion. Therefore, the amount of Tris solution required to cause the same increase in pH level is less than that of equimolar

  5. Behavior of the sorption of {sup 60} Co in aqueous solution on inorganic materials as function of p H; Comportamiento de la sorcion del {sup 60} Co en solucion acuosa sobre materiales inorganicos como una funcion del pH

    Energy Technology Data Exchange (ETDEWEB)

    Granados, F.; Bulbulian, S.; Solache R, M. [ININ, 52045 Ocoyoacac, Estado de Mexico (Mexico); Bertin, V. [UAM-I, 09340 Mexico D.F. (Mexico)

    2004-07-01

    The sorption of the {sup 60} Co is evaluated in aqueous solution on Mg O, MnO{sub 2}, TiO{sub 2}, Sn O, activated carbon and hydrotalcite calcined as a function of the p H, using the method for lots and quantifying at the {sup 60} Co for gamma spectrometry. Likewise it was explained the one behavior of the sorption of the {sup 60} Co in the materials with base in the chemical species of this radioactive isotope in aqueous solution. The chemical species of the {sup 60} Co in solution were identified by electrophoresis of high voltage for the different p H values. It was found that under the experimental conditions, the {sup 60} Co showed a significant sorption on MnO{sup 2}, TiO{sup 2} and activated carbon. On the other hand, in Mg O, Sn O and calcined hydrotalcite also was observed a sorption, although in smaller quantities. The studied hydrated metallic oxides retained the {sup 60} Co for ion exchange via. It was found that the {sup 60} Co was present as a cationic specie to p H 1, 3, 5 and 7 and like a neutral specie to alkaline p H. (Author)

  6. Effect of pH and phosphate on calcium carbonate polymorphs precipitated at near-freezing temperature

    NARCIS (Netherlands)

    Hu, Yu-Bin; Wolthers, Mariëtte; Wolf-Gladrow, Dieter A.; Nehrke, Gernot

    2015-01-01

    The effects of pH and phosphate on the precipitation of calcium carbonate polymorphs from aqueous solution were investigated. Experiments were carried out at near-freezing temperature and two different pH conditions (pH 13.4 and 9.0). At each pH condition, solutions having different concentrations

  7. The effect of pH and chloride concentration on the stability and antimicrobial activity of chlorine-based sanitizers.

    Science.gov (United States)

    Waters, Brian W; Hung, Yen-Con

    2014-04-01

    Chlorinated water and electrolyzed oxidizing (EO) water solutions were made to compare the free chlorine stability and microbicidal efficacy of chlorine-containing solutions with different properties. Reduction of Escherichia coli O157:H7 was greatest in fresh samples (approximately 9.0 log CFU/mL reduction). Chlorine loss in "aged" samples (samples left in open bottles) was greatest (approximately 40 mg/L free chlorine loss in 24 h) in low pH (approximately 2.5) and high chloride (Cl(-) ) concentrations (greater than 150 mg/L). Reduction of E. coli O157:H7 was also negatively impacted (pH and high Cl(-) . Higher pH values (approximately 6.0) did not appear to have a significant effect on free chlorine loss or numbers of surviving microbial cells when fresh and aged samples were compared. This study found chloride levels in the chlorinated and EO water solutions had a reduced effect on both free chlorine stability and its microbicidal efficacy in the low pH solutions. Greater concentrations of chloride in pH 2.5 samples resulted in decreased free chlorine stability and lower microbicidal efficacy. © 2014 Institute of Food Technologists®

  8. pH dependent polymeric micelle adsorption

    Energy Technology Data Exchange (ETDEWEB)

    McLean, S C; Gee, M L [The University of Melbourne, VIC (Australia). School of Chemistry

    2003-07-01

    Full text: Poly(2-vinylpyridine)-poly(ethylene oxide) (P2VP-PEO) shows potential as a possible drug delivery system for anti-tumour drugs since it forms pH dependent polymeric micelles. Hence to better understand the adsorption behaviour of this polymer we have studied the interaction forces between layers of P2VP-PEO adsorbed onto silica as a function of solution pH using an Atomic Force Microscope (AFM). When P2VP-PEO is initially adsorbed above the pKa of the P2VP block, P2VP-PEO adsorbs from solution as micelles that exist as either partially collapsed- or a hemi-micelles at the silica surface. Below the pKa of P2VP, the P2VP-PEO adsorbs as unimers, forming a compact layer with little looping and tailing into solution. When initial adsorption of P2VP-PEO is in the form of unimers, any driving force to self-assembly of the now charge neutral polymer is kinetically hindered. Hence, after initial adsorption at pH 3.6, a subsequent increase in pH to 6.6 results in a slow surface restructuring towards self-assembly and equilibrium. When the pH is increased from pH 6.6 to 9.7 there is a continuation of the evolution of the system to its equilibrium position during which the adsorbed P2VP-PEO unimers continue to 'unravel' from the surface, extending away from it, towards eventual complete surface self-assembly.

  9. Effect of precursor solutions stirring on deep level defects concentration and spatial distribution in low temperature aqueous chemical synthesis of zinc oxide nanorods

    Energy Technology Data Exchange (ETDEWEB)

    Alnoor, Hatim, E-mail: hatim.alnoor@liu.se; Chey, Chan Oeurn; Pozina, Galia; Willander, Magnus; Nur, Omer [Department of Science and Technology (ITN), Campus Norrköping, Linköping University, SE-601 74 Norrköping (Sweden); Liu, Xianjie; Khranovskyy, Volodymyr [Department of Physics, Chemistry and Biology (IFM), Linköping University, SE-583 81 Linköping (Sweden)

    2015-08-15

    Hexagonal c-axis oriented zinc oxide (ZnO) nanorods (NRs) with 120-300 nm diameters are synthesized via the low temperature aqueous chemical route at 80 °C on silver-coated glass substrates. The influence of varying the precursor solutions stirring durations on the concentration and spatial distributions of deep level defects in ZnO NRs is investigated. Room temperature micro-photoluminesnce (μ-PL) spectra were collected for all samples. Cathodoluminescence (CL) spectra of the as-synthesized NRs reveal a significant change in the intensity ratio of the near band edge emission (NBE) to the deep-level emission (DLE) peaks with increasing stirring durations. This is attributed to the variation in the concentration of the oxygen-deficiency with increasing stirring durations as suggested from the X-ray photoelectron spectroscopy analysis. Spatially resolved CL spectra taken along individual NRs revealed that stirring the precursor solutions for relatively short duration (1-3 h), which likely induced high super saturation under thermodynamic equilibrium during the synthesis process, is observed to favor the formation of point defects moving towards the tip of the NRs. In contrary, stirring for longer duration (5-15 h) will induce low super saturation favoring the formation of point defects located at the bottom of the NRs. These findings demonstrate that it is possible to control the concentration and spatial distribution of deep level defects in ZnO NRs by varying the stirring durations of the precursor solutions.

  10. Desirable levels of exchangeable K and Ca and their concentration in the soil solution to reduce uptake of radioactive Cs by rice plants

    International Nuclear Information System (INIS)

    Sekimoto, Hitoshi; Yamada, Takashi; Hotsuki, Tomoe; Matsuzaki, Akio; Mimura, Tetsuro

    2014-01-01

    K in the soil solution can control the uptake of radioactive Cs by rice plants, but this control is not accomplished only by K; it is affected by other ionic species. It is therefore important to investigate uptake of radioactive Cs from the perspective of the concentration of major cations such as Ca in the soil solution and the levels of exchangeable cations in the soil. To clarify the effects of K and Ca in the soil solution and of the levels of soil exchangeable cations to prevent uptake of radioactive Cs, we conducted a pot experiment and field experiments in a paddy soil in 2011 and 2012. To reduce the uptake of radioactive Cs, it was necessary to achieve a K concentration in the soil solution of 0.5 mmol L"-"1, and a Ca concentration higher than 2 mmol L"-"1 based on the results of the pot experiment. In addition, we obtained the desirable levels of exchangeable cations and the cation exchange capacity (CEC) in the soil from previous reports and the results of our field experiments. On this basis, we propose the following threshold levels for exchangeable cations and CEC in the soil as a standard: 0.53 K cmol_c kg"-"1, 18.0 Ca cmol_c kg"-"1, 2.0 Mg cmol_c kg"-"1, i.e. 25 mg K_2O 100 g"-"1, 505 mg CaO 100 g"-"1, 40 Mg O mg 100 g"-"1, and a CEC of 30 cmol_c kg"-"1. Converting these values into the corresponding levels in the soil solution, we obtained concentrations of 0.71 mmol K L"-"1, 4.22 mmol Ca L"-"1, and 1.35 mmol Mg L"-"1. These levels are within the improving standard for fertility of paddy soils in Japan. Consequently, it will be necessary to improve the fertility of paddy soils to control the uptake of radioactive Cs by rice plants. (author)

  11. [Dynamics of riboflavin level in aqueous humour of anterior chamber of experimental animals under standard stroma saturation by ultraviolet corneal cross-linking solutions].

    Science.gov (United States)

    Bikbov, M M; Shevchuk, N E; Khalimov, A R; Bikbova, G M

    To evaluate the dynamics of riboflavin changes in the aqueous humour of the anterior chamber (AHAC) of rabbits' eyes during standard ultraviolet (UV) cross-linking with account to the area of corneal debridement. Forty two rabbits were studied sequentially. The following solutions of riboflavin were used for cornea saturation: IR - 0.1% isosmotic riboflavin, D - Dextralink (0.1% riboflavin with 20% dextran), R - 0.1% riboflavin with 1.0% hydroxypropylmethylcellulose (HPMC). Each solution was evaluated in 3 groups that differed in the diameter of corneal debridement: group 1 - Epi-Off 3 mm (IR-3, D-3, P-3), group 2 - Epi-Off 6 mm (IR-6, D-6, R-6), and group 3 - Epi-Off 9 mm (IR-9, D-9, R-9). Aqueous humour sampling (252 samples in total) was performed in 10-minute intervals within a 60 minute period. Riboflavin levels were measured by enzyme-linked immunoassay (ID-Vit microbiological test system; Immundiagnostik, Germany). Stable growth rates of riboflavin level in the AHAC (with maximum values reached at 30-40 min) were observed for solutions D and R, regardless of the variant of corneal debridement. Moreover, throughout the whole follow-up period and regardless of the area of corneal debridement, the solution D provided a relatively lower concentration of riboflavin in the AHAC as compared to the two other solutions. At 30 minutes, when the cornea was considered ready for UV irradiation, the riboflavin level in the AHAC ranged from 385±26.1 μg/l (D-9) to 665±28 μg/l (R-9). In groups IR-9, IR-6, P-6, IR-3, and P-3 riboflavin levels were found to be in the same range starting at 20 minutes. However, even a sufficient concentration of riboflavin in the cornea or AHAC cannot guarantee safe and effective UV cross-linking, since the removed epithelium limits the area of the stroma that can be saturated with riboflavin, while the area of UV exposure is 8-10 mm. Safe and efficient standard UV cross-linking may be performed only under sufficient saturation of the

  12. Image understanding systems based on the unifying representation of perceptual and conceptual information and the solution of mid-level and high-level vision problems

    Science.gov (United States)

    Kuvychko, Igor

    2001-10-01

    Vision is a part of a larger information system that converts visual information into knowledge structures. These structures drive vision process, resolving ambiguity and uncertainty via feedback, and provide image understanding, that is an interpretation of visual information in terms of such knowledge models. A computer vision system based on such principles requires unifying representation of perceptual and conceptual information. Computer simulation models are built on the basis of graphs/networks. The ability of human brain to emulate similar graph/networks models is found. That means a very important shift of paradigm in our knowledge about brain from neural networks to the cortical software. Starting from the primary visual areas, brain analyzes an image as a graph-type spatial structure. Primary areas provide active fusion of image features on a spatial grid-like structure, where nodes are cortical columns. The spatial combination of different neighbor features cannot be described as a statistical/integral characteristic of the analyzed region, but uniquely characterizes such region itself. Spatial logic and topology naturally present in such structures. Mid-level vision processes like clustering, perceptual grouping, multilevel hierarchical compression, separation of figure from ground, etc. are special kinds of graph/network transformations. They convert low-level image structure into the set of more abstract ones, which represent objects and visual scene, making them easy for analysis by higher-level knowledge structures. Higher-level vision phenomena like shape from shading, occlusion, etc. are results of such analysis. Such approach gives opportunity not only to explain frequently unexplainable results of the cognitive science, but also to create intelligent computer vision systems that simulate perceptional processes in both what and where visual pathways. Such systems can open new horizons for robotic and computer vision industries.

  13. Expression of characteristics of ammonium nutrition as affected by pH of the root medium

    Science.gov (United States)

    Chaillou, S.; Vessey, J. K.; Morot-Gaudry, J. F.; Raper, C. D. Jr; Henry, L. T.; Boutin, J. P.

    1991-01-01

    To study the effect of root-zone pH on characteristic responses of NH4+ -fed plants, soybeans (Glycine max inverted question markL. inverted question mark Merr. cv. Ransom) were grown in flowing solution culture for 21 d on four sources of N (1.0 mol m-3 NO3-, 0.67 mol m-3 NO3- plus 0.33 mol m-3 NH4+, 0.33 mol m-3 NO3- plus 0.67 mol m-3 NH4+, and 1.0 mol m-3 NH4+) with nutrient solutions maintained at pH 6.0, 5.5, 5.0, and 4.5. Amino acid concentration increased in plants grown with NH4+ as the sole source of N at all pH levels. Total amino acid concentration in the roots of NH4+ -fed plants was 8 to 10 times higher than in NO3(-)-fed plants, with asparagine accounting for more than 70% of the total in the roots of these plants. The concentration of soluble carbohydrates in the leaves of NH4+ -fed plants was greater than that of NO3(-)-fed plants, but was lower in roots of NH4+ -fed plants, regardless of pH. Starch concentration was only slightly affected by N source or root-zone pH. At all levels of pH tested, organic acid concentration in leaves was much lower when NH4+ was the sole N source than when all or part of the N was supplied as NO3-. Plants grown with mixed NO3- plus NH4+ N sources were generally intermediate between NO3(-)- and NH4+ -fed plants. Thus, changes in tissue composition characteristic of NH4+ nutrition when root-zone pH was maintained at 4.5 and growth was reduced, still occurred when pH was maintained at 5.0 or above, where growth was not affected. The changes were slightly greater at pH 4.5 than at higher pH levels.

  14. The Semen pH Affects Sperm Motility and Capacitation.

    Science.gov (United States)

    Zhou, Ji; Chen, Li; Li, Jie; Li, Hongjun; Hong, Zhiwei; Xie, Min; Chen, Shengrong; Yao, Bing

    2015-01-01

    As the chemical environment of semen can have a profound effect on sperm quality, we examined the effect of pH on the motility, viability and capacitation of human sperm. The sperm in this study was collected from healthy males to avoid interference from other factors. The spermatozoa cultured in sperm nutrition solution at pH 5.2, 6.2, 7.2 and 8.2 were analyzed for sperm total motility, progressive motility (PR), hypo-osmotic swelling (HOS) rate, and sperm penetration. Our results showed that these parameters were similar in pH 7.2 and 8.2 sperm nutrition solutions, but decreased in pH 5.2 and 6.2 solutions. The HOS rate exhibited positive correlation with the sperm total motility and PR. In addition, the sperm Na(+)/K(+)-ATPase activity at different pHs was measured, and the enzyme activity was significantly lower in pH 5.2 and 6.2 media, comparing with that in pH 8.2 and pH 7.2 solutions. Using flow cytometry (FCM) and laser confocal scanning microscopy (LCSM) analysis, the intracellular Ca2(+ )concentrations of sperm cultured in sperm capacitation solution at pH 5.2, 6.2, 7.2 and 8.2 were determined. Compared with that at pH 7.2, the mean fluorescence intensity of sperm in pH 5.2 and 6.2 media decreased significantly, while that of pH 8.2 group showed no difference. Our results suggested that the declined Na(+)/K(+)-ATPase activity at acidic pHs result in decreased sperm movement and capacitation, which could be one of the mechanisms of male infertility.

  15. Determining pH of strip-mine spoils

    Science.gov (United States)

    W. A. Berg

    1969-01-01

    Results with the LaMotte-Morgan method for determining soil pH-or the solution modification of this method-usually agreed fairly well with the results from using a pH meter, the recognized standard. Results obtained with the Soiltex and Hellige-Truog methods often deviated somewhat from the pH meter readings; and the Hydrion papers and the Kelway pH tester often gave...

  16. Differential Sensor for PH Monitoring of Environmental Objects

    Directory of Open Access Journals (Sweden)

    Romanenko Sergey

    2016-01-01

    Full Text Available Differential pH sensor is proposed. Reference electrode and measuring electrode are the same type. Reference electrode is immersed in standard buffer solution with known pH value. The differential pH sensor has longer service life as compared with the traditionally used sensors with silver chloride reference electrode. Ultrasonic cleaning system is proposed to clean the primary measuring transducer from pollution that form as result of silting during long-term operation with the sensor.

  17. Chapter A6. Section 6.4. pH

    Science.gov (United States)

    Wilde, Franceska D.; Busenberg, Eurybiades; Radtke, Dean B.

    2006-01-01

    Measurement of pH is critical to the understanding of the viability and vulnerability of environmental waters and is considered a master variable in determining the aqueous geochemistry of an aqueous system. pH is a measure that represents the hydrogen-ion concentration (activity) of a solution. This section of the National Field Manual (NFM) describes U.S. Geological Survey (USGS) guidance and protocols for measurement of pH in ground and surface waters.

  18. A Simplified Solution for Calculating the Phreatic Line and Slope Stability during a Sudden Drawdown of the Reservoir Water Level

    Directory of Open Access Journals (Sweden)

    Guanhua Sun

    2018-01-01

    Full Text Available On the basis of the Boussinesq unsteady seepage differential equation, a new simplified formula for the phreatic line of slopes under the condition of decreasing reservoir water level is derived by means of the Laplacian matrix and its inverse transform. In this context, the expression of normal stress on the slip surface under seepage forces is deduced, and a procedure for obtaining the safety factors under hydrodynamic forces is proposed. A case study of the Three Gorges Reservoir is used to analyze the influences of the water level, decreasing velocity and the permeability coefficient on slope stability.

  19. Protein aggregation in aqueous casein solution. Effect of irradiation, dose level, concentration, storage and additives (carbohydrate and lipid)

    Energy Technology Data Exchange (ETDEWEB)

    Yousri, R M

    1980-06-01

    From the vast amount of research efforts dealing with various aspects of radiation effects on foods and food components, it is apparent up to now that much remains to be studied in depth, much may have to be added or corrected about radiation-induced physico-chemical changes in foods. A great many reactions that take place when foodstuffs are subjected to ionizing radiation are still not fully understood. The better understanding of some of the radiation-induced changes in pure proteins as such or in mixture with other food constituents could yield much data which could be meaningfully extrapolated to intact foods and consequently could help to improve the assessment of the wholesomeness of irradiated foods. It was the purpose of our investigations to elucidate some of the changes in the chemical structure of a pure protein (casein), irradiated as such or with added carbohydrate and/or lipid. The effect of subsequent storage of the irradiated solutions has been also examined. The formation of protein aggregates was studied by gel filtration technique. The application of thin-layer gel filtration, its speed and adaptability to very small samples facilitated the measurements of the extent of aggregation which occurred in protein molecules after irradiation.

  20. Normal values in ambulatory oesophageal pH monitoring at two levels in Spain Valores normales en pHmetría esofágica ambulatoria a dos niveles en España

    Directory of Open Access Journals (Sweden)

    2010-07-01

    Full Text Available Aim: upper oesophageal pH monitoring may play a significant role in the study of extra-oesophageal GERD, but limited normal data are available to date. Our aim was to develop a large series of normal values of proximal oesophageal acidification. Methods: 155 healthy volunteers (74 male participated in a multi-centre national study including oesophageal manometry and 24 hours oesophageal pH monitoring using two electrodes individually located 5 cm above the LOS and 3 cm below the UOS. Results: 130 participants with normal manometry completed all the study. Twelve of them were excluded for inadequate pH tests. Twenty-seven subjects had abnormal conventional pH. The remaining 91 subjects (37 M; 18-72 yrs age range formed the reference group for normality. At the level of the upper oesophagus, the 95th percentile of the total number of reflux events was 30, after eliminating the meal periods 22, and after eliminating also the pseudo-reflux events 18. Duration of the longest episodes was 5, 4 and 4 min, respectively (3.5 min in upright and 0.5 min in supine. The upper limit for the percentage of acid exposure time was 1.35, 1.05 and 0.95%, respectively. No reflux events were recorded in the upper oesophagus in 8 cases. Conclusion: this is the largest series of normal values of proximal oesophageal reflux that confirm the existence of acid reflux at that level in healthy subjects, in small quantity and unrelated to age or gender. Our data support the convenience of excluding pseudo-reflux events and meal periods from analysis.Objetivo: la pHmetría con electrodo proximal puede jugar un papel importante en el estudio de las manifestaciones extraesofágicas de la ERGE, pero no existen series amplias que permitan establecer los valores de referencia con fiabilidad. Métodos: se incluyeron 155 voluntarios sanos (74 H en un estudio multicéntrico a nivel nacional con manometría esofágica y pHmetría de 24 horas con dos electrodos individuales a 5 cm por

  1. Renewable Energy Prices in State-Level Feed-in Tariffs: Federal Law Constraints and Possible Solutions

    Energy Technology Data Exchange (ETDEWEB)

    Hempling, S.; Elefant, C.; Cory, K.; Porter, K.

    2010-01-01

    State legislatures and state utility commissions trying to attract renewable energy projects are considering feed-in tariffs, which obligate retail utilities to purchase electricity from renewable producers under standard arrangements specifying prices, terms, and conditions. The use of feed-in tariffs simplifies the purchase process, provides revenue certainty to generators, and reduces the cost of financing generating projects. However, some argue that federal law--including the Public Utility Regulatory Policies Act of 1978 (PURPA) and the Federal Power Act of 1935 (FPA)--constrain state-level feed-in tariffs. This report seeks to reduce the legal uncertainties for states contemplating feed-in tariffs by explaining the constraints imposed by federal statutes. It describes the federal constraints, identifies transaction categories that are free of those constraints, and offers ways for state and federal policymakers to interpret or modify existing law to remove or reduce these constraints. This report proposes ways to revise these federal statutes. It creates a broad working definition of a state-level feed-in tariff. Given this definition, this report concludes there are paths to non-preempted, state-level feed-in tariffs under current federal law.

  2. A multi-level quantum mechanics and molecular mechanics study of SN2 reaction at nitrogen: NH2Cl + OH(-) in aqueous solution.

    Science.gov (United States)

    Lv, Jing; Zhang, Jingxue; Wang, Dunyou

    2016-02-17

    We employed a multi-level quantum mechanics and molecular mechanics approach to study the reaction NH2Cl + OH(-) in aqueous solution. The multi-level quantum method (including the DFT method with both the B3LYP and M06-2X exchange-correlation functionals and the CCSD(T) method, and both methods with the aug-cc-pVDZ basis set) was used to treat the quantum reaction region in different stages of the calculation in order to obtain an accurate potential of mean force. The obtained free energy activation barriers at the DFT/MM level of theory yielded a big difference of 21.8 kcal mol(-1) with the B3LYP functional and 27.4 kcal mol(-1) with the M06-2X functional respectively. Nonetheless, the barrier heights become very close when shifted from DFT to CCSD(T): 22.4 kcal mol(-1) and 22.9 kcal mol(-1) at CCSD(T)(B3LYP)/MM and CCSD(T)(M06-2X)/MM levels of theory, respectively. The free reaction energy obtained using CCSD(T)(M06-2X)/MM shows an excellent agreement with the one calculated using the available gas-phase data. Aqueous solution plays a significant role in shaping the reaction profile. In total, the water solution contributes 13.3 kcal mol(-1) and 14.6 kcal mol(-1) to the free energy barrier heights at CCSD(T)(B3LYP)/MM and CCSD(T)(M06-2X)/MM respectively. The title reaction at nitrogen is a faster reaction than the corresponding reaction at carbon, CH3Cl + OH(-).

  3. Low pH Cements

    International Nuclear Information System (INIS)

    Savage, David; Benbow, Steven

    2007-05-01

    speciation of silicon at pH 10 has a significant impact upon the solubility of montmorillonite and would thus constitute a logical choice of pH limit for cement-derived pore fluids, but it is unlikely that cement-based grouts could be developed to meet this limit. Control of mass transport by diffusion processes serves as a significant constraint over the amount of bentonite that can be degraded. Computer simulations indicate that porosity reduction is likely at the interface between cement and bentonite. However, it is not clear how the transport properties of bentonite may be modified due to mineral alteration processes. There are considerable uncertainties concerning the precise mechanism of the rate of montmorillonite dissolution at elevated pH. The rate of dissolution may be inhibited by the presence of dissolved Si (and perhaps Al), but this mechanism has yet to be confirmed at high pH. The type of secondary minerals assumed to form from cement-bentonite interaction will also have a significant impact upon the rate of montmorillonite dissolution. Low-pH cement systems have received little attention thus far regarding the development of models for the chemical evolution of pore fluids. Low Ca/Si CSH gels show preferential leaching of Si, which is in marked contrast with gels of greater Ca/Si ratio. Models apparently capable of predicting pore fluid composition coexisting with low Ca/Si CSH gels are a modified Berner model and a solid-solution model proposed by Sugiyama and Fujita. The solubility of silica in pore fluids coexisting with low Ca/Si gels may exceed that of amorphous silica, and may pose problems regarding the stability of montmorillonite in relation to framework silicates such as feldspars. However, the potential rate of conversion of montmorillonite to feldspar under repository conditions is uncertain. It is necessary to use additives such as super plasticiser to improve the workability of low-pH cements. These organic additives have the potential to

  4. Low pH Cements

    Energy Technology Data Exchange (ETDEWEB)

    Savage, David; Benbow, Steven [Quintessa Ltd., Henley-on-Thames (United Kingdom)

    2007-05-15

    speciation of silicon at pH 10 has a significant impact upon the solubility of montmorillonite and would thus constitute a logical choice of pH limit for cement-derived pore fluids, but it is unlikely that cement-based grouts could be developed to meet this limit. Control of mass transport by diffusion processes serves as a significant constraint over the amount of bentonite that can be degraded. Computer simulations indicate that porosity reduction is likely at the interface between cement and bentonite. However, it is not clear how the transport properties of bentonite may be modified due to mineral alteration processes. There are considerable uncertainties concerning the precise mechanism of the rate of montmorillonite dissolution at elevated pH. The rate of dissolution may be inhibited by the presence of dissolved Si (and perhaps Al), but this mechanism has yet to be confirmed at high pH. The type of secondary minerals assumed to form from cement-bentonite interaction will also have a significant impact upon the rate of montmorillonite dissolution. Low-pH cement systems have received little attention thus far regarding the development of models for the chemical evolution of pore fluids. Low Ca/Si CSH gels show preferential leaching of Si, which is in marked contrast with gels of greater Ca/Si ratio. Models apparently capable of predicting pore fluid composition coexisting with low Ca/Si CSH gels are a modified Berner model and a solid-solution model proposed by Sugiyama and Fujita. The solubility of silica in pore fluids coexisting with low Ca/Si gels may exceed that of amorphous silica, and may pose problems regarding the stability of montmorillonite in relation to framework silicates such as feldspars. However, the potential rate of conversion of montmorillonite to feldspar under repository conditions is uncertain. It is necessary to use additives such as super plasticiser to improve the workability of low-pH cements. These organic additives have the potential to

  5. Comparison of costs for solidification of high-level radioactive waste solutions: glass monoliths vs metal matrices

    International Nuclear Information System (INIS)

    Jardine, L.J.; Carlton, R.E.; Steindler, M.J.

    1981-05-01

    A comparative economic analysis was made of four solidification processes for liquid high-level radioactive waste. Two processes produced borosilicate glass monoliths and two others produced metal matrix composites of lead and borosilicate glass beads and lead and supercalcine pellets. Within the uncertainties of the cost (1979 dollars) estimates, the cost of the four processes was about the same, with the major cost component being the cost of the primary building structure. Equipment costs and operating and maintenance costs formed only a small portion of the building structure costs for all processes

  6. Probing the Energy Level Alignment and the Correlation with Open-Circuit Voltage in Solution-Processed Polymeric Bulk Heterojunction Photovoltaic Devices.

    Science.gov (United States)

    Yang, Qing-Dan; Li, Ho-Wa; Cheng, Yuanhang; Guan, Zhiqiang; Liu, Taili; Ng, Tsz-Wai; Lee, Chun-Sing; Tsang, Sai-Wing

    2016-03-23

    Energy level alignment at the organic donor and acceptor interface is a key to determine the photovoltaic performance in organic solar cells, but direct probing of such energy alignment is still challenging especially for solution-processed bulk heterojunction (BHJ) thin films. Here we report a systematic investigation on probing the energy level alignment with different approaches in five commonly used polymer:[6,6]-phenyl-C71-butyric acid methyl ester (PCBM) BHJ systems. We find that by tuning the weight ratio of polymer to PCBM the electronic features from both polymer and PCBM can be obtained by photoemission spectroscopy. Using this approach, we find that some of the BHJ blends simply follow vacuum level alignment, but others show strong energy level shifting as a result of Fermi level pinning. Independently, by measuring the temperature-dependent open-circuit voltage (VOC), we find that the effective energy gap (Eeff), the energy difference between the highest occupied molecular orbital of the polymer donor (EHOMO-D) and lowest unoccupied molecular orbital of the PCBM acceptor (ELUMO-A), obtained by photoemission spectroscopy in all polymer:PCBM blends has an excellent agreement with the extrapolated VOC at 0 K. Consequently, the photovoltage loss of various organic BHJ photovoltaic devices at room temperature is in a range of 0.3-0.6 V. It is believed that the demonstrated direct measurement approach of the energy level alignment in solution-processed organic BHJ will bring deeper insight into the origin of the VOC and the corresponding photovoltage loss mechanism in organic photovoltaic cells.

  7. An improved red blood cell additive solution maintains 2,3-diphosphoglycerate and adenosine triphosphate levels by an enhancing effect on phosphofructokinase activity during cold storage.

    Science.gov (United States)

    Burger, Patrick; Korsten, Herbert; De Korte, Dirk; Rombout, Eva; Van Bruggen, Robin; Verhoeven, Arthur J

    2010-11-01

    Current additive solutions (ASs) for red blood cells (RBCs) do not maintain constant 2,3-diphosphoglycerate (DPG) and adenosine triphosphate (ATP) levels during cold storage. We have previously shown that with a new AS called phosphate-adenine-glucose-guanosine-gluconate-mannitol (PAGGGM), both 2,3-DPG and ATP could be maintained throughout storage for 35 days. In this study, the mechanism underlying the effect of PAGGGM on RBC storage was studied in more detail. By using double-erythrocytapheresis units (leukoreduced), a direct comparison could be made between the current AS saline-adenine-glucose-mannitol (SAGM) and the experimental solution PAGGGM. During cold storage, several in vitro characteristics were analyzed. In agreement with our previous findings with single RBCs, PAGGGM maintained 2,3-DPG and ATP levels for 35 days of cold storage. Furthermore, glucose consumption and lactate production were higher in PAGGGM units during the first 21 days of cold storage. Fructose-1,6-diphophate and dihydroxyacetone phosphate levels were also increased during the first 21 days of storage in PAGGGM units. These results indicate that it is likely that phosphofructokinase (PFK) activity is enhanced in PAGGGM units relative to SAGM units. After 21 days, PFK activity also decreases in PAGGGM units, but sufficient metabolic reserve in these units prevents depletion of 2,3-DPG and ATP. © 2010 American Association of Blood Banks.

  8. Microfabricated Collector-Generator Electrode Sensor for Measuring Absolute pH and Oxygen Concentrations.

    Science.gov (United States)

    Dengler, Adam K; Wightman, R Mark; McCarty, Gregory S

    2015-10-20

    Fast-scan cyclic voltammetry (FSCV) has attracted attention for studying in vivo neurotransmission due to its subsecond temporal resolution, selectivity, and sensitivity. Traditional FSCV measurements use background subtraction to isolate changes in the local electrochemical environment, providing detailed information on fluctuations in the concentration of electroactive species. This background subtraction removes information about constant or slowly changing concentrations. However, determination of background concentrations is still important for understanding functioning brain tissue. For example, neural activity is known to consume oxygen and produce carbon dioxide which affects local levels of oxygen and pH. Here, we present a microfabricated microelectrode array which uses FSCV to detect the absolute levels of oxygen and pH in vitro. The sensor is a collector-generator electrode array with carbon microelectrodes spaced 5 μm apart. In this work, a periodic potential step is applied at the generator producing transient local changes in the electrochemical environment. The collector electrode continuously performs FSCV enabling these induced changes in concentration to be recorded with the sensitivity and selectivity of FSCV. A negative potential step applied at the generator produces a transient local pH shift at the collector. The generator-induced pH signal is detected using FSCV at the collector and correlated to absolute solution pH by postcalibration of the anodic peak position. In addition, in oxygenated solutions a negative potential step at the generator produces hydrogen peroxide by reducing oxygen. Hydrogen peroxide is detected with FSCV at the collector electrode, and the magnitude of the oxidative peak is proportional to absolute oxygen concentrations. Oxygen interference on the pH signal is minimal and can be accounted for with a postcalibration.

  9. Improvement of multi-level resistive switching characteristics in solution-processed AlO x -based non-volatile resistive memory using microwave irradiation

    Science.gov (United States)

    Kim, Seung-Tae; Cho, Won-Ju

    2018-01-01

    We fabricated a resistive random access memory (ReRAM) device on a Ti/AlO x /Pt structure with solution-processed AlO x switching layer using microwave irradiation (MWI), and demonstrated multi-level cell (MLC) operation. To investigate the effect of MWI power on the MLC characteristics, post-deposition annealing was performed at 600-3000 W after AlO x switching layer deposition, and the MLC operation was compared with as-deposited (as-dep) and conventional thermally annealing (CTA) treated devices. All solution-processed AlO x -based ReRAM devices exhibited bipolar resistive switching (BRS) behavior. We found that these devices have four-resistance states (2 bits) of MLC operation according to the modulation of the high-resistance state (HRSs) through reset voltage control. Particularly, compared to the as-dep and CTA ReRAM devices, the MWI-treated ReRAM devices showed a significant increase in the memory window and stable endurance for multi-level operation. Moreover, as the MWI power increased, excellent MLC characteristics were exhibited because the resistance ratio between each resistance state was increased. In addition, it exhibited reliable retention characteristics without deterioration at 25 °C and 85 °C for 10 000 s. Finally, the relationship between the chemical characteristics of the solution-processed AlO x switching layer and BRS-based multi-level operation according to the annealing method and MWI power was investigated using x-ray photoelectron spectroscopy.

  10. Effect of precursor solutions stirring on deep level defects concentration and spatial distribution in low temperature aqueous chemical synthesis of zinc oxide nanorods

    Directory of Open Access Journals (Sweden)

    Hatim Alnoor

    2015-08-01

    Full Text Available Hexagonal c-axis oriented zinc oxide (ZnO nanorods (NRs with 120-300 nm diameters are synthesized via the low temperature aqueous chemical route at 80 °C on silver-coated glass substrates. The influence of varying the precursor solutions stirring durations on the concentration and spatial distributions of deep level defects in ZnO NRs is investigated. Room temperature micro-photoluminesnce (μ-PL spectra were collected for all samples. Cathodoluminescence (CL spectra of the as-synthesized NRs reveal a significant change in the intensity ratio of the near band edge emission (NBE to the deep-level emission (DLE peaks with increasing stirring durations. This is attributed to the variation in the concentration of the oxygen-deficiency with increasing stirring durations as suggested from the X-ray photoelectron spectroscopy analysis. Spatially resolved CL spectra taken along individual NRs revealed that stirring the precursor solutions for relatively short duration (1-3 h, which likely induced high super saturation under thermodynamic equilibrium during the synthesis process, is observed to favor the formation of point defects moving towards the tip of the NRs. In contrary, stirring for longer duration (5-15 h will induce low super saturation favoring the formation of point defects located at the bottom of the NRs. These findings demonstrate that it is possible to control the concentration and spatial distribution of deep level defects in ZnO NRs by varying the stirring durations of the precursor solutions.

  11. PhD Dissertations

    OpenAIRE

    Redazione Reti Medievali (a cura di)

    2010-01-01

    Report of PhD Dissertations.Anna Airò La scrittura delle regole. Politica e istituzioni a Taranto nel Quattrocento, Tesi di dottorato di ricerca in Storia medievale, Università degli studi di Firenze, 2005 Pasquale Arfé La Clavis Physicae II (316-529) di Honorius Augustodunensis. Studio ed edizione critica, Tesi di dottorato in Storia della filosofia medievale, Università degli Studi di Napoli "L'Orientale", 2005 Alessandro Azzimonti Scrittura agiografica e strutture di potere nell'Italia c...

  12. In vitro simulation of fretting-corrosion in hip implant modular junctions: The influence of pH.

    Science.gov (United States)

    Royhman, Dmitry; Patel, Megha; Jacobs, Joshua J; Wimmer, Markus A; Hallab, Nadim J; Mathew, Mathew T

    2018-02-01

    The fretting-corrosion behavior of mixed metal contacts is affected by various mechanical and electrochemical parameters. Crevice conditions at the junction and patient-specific pathologies can affect the pH of the prosthetic environment. The main objective of this study is to understand the effect of pH variation at the stem/head junction of the hip implant under fretting corrosion exposure. We hypothesized that pH will have a significant influence on the fretting-corrosion behavior hip implant modular junctions. A custom-made setup was used to evaluate the fretting corrosion behavior of hip implant modular junctions. A Newborn calf serum solution (30 g/L protein content) was used to simulate the synovial fluid environment. A sinusoidal fretting motion, with a displacement amplitude of +50 µm, was applied to the Ti alloy rod. The effects of pathology driven, periprosthetic pH variation were simulated at four different pH levels (3.0, 4.5, 6.0 and 7.6). Electrochemical and mechanical properties were evaluated before, during, and after the applied fretting motion. The impedance of the system was increased in response to the fretting motion. The hysteresis tangential load/displacement behavior was not affected by pH level. The worn surfaces of CoCrMo pins exhibited the presence of tribolayer or organic deposits, in the pH 4.5 group, which may explain the lower drop in potential and mass loss observed in that group. Mechanically dominated wear mechanisms, namely, adhesive wear was shown in the pH 7.6 group, which may account for a higher potential drop and metal content loss. This study suggests that the fretting-corrosion mechanisms in hip implant are affected by the pH levels of the surrounding environment and patient-specific factors. Copyright © 2017. Published by Elsevier Ltd.

  13. Effects of Fuel to Synthesis of CaTiO3 by Solution Combustion Synthesis for High-Level Nuclear Waste Ceramics.

    Science.gov (United States)

    Jung, Choong-Hwan; Kim, Yeon-Ku; Han, Young-Min; Lee, Sang-Jin

    2016-02-01

    A solution combustion process for the synthesis of perovskite (CaTiO3) powders is described. Perovskite is one of the crystalline host matrics for the disposal of high-level radioactive wastes (HLW) because it immobilizes Sr and Lns elements by forming solid solutions. Solution combustion synthesis, which is a self-sustaining oxi-reduction reaction between nitrate and organic fuel, the exothermic reaction, and the heat evolved convert the precursors into their corresponding oxide products above 1100 degrees C in air. To investigate the effects of amino acid on the combustion reaction, various types of fuels were used; a glycine, amine and carboxylic ligand mixture. Sr, La and Gd-nitrate with equivalent amounts of up to 20% of CaTiO3 were mixed with Ca and Ti nitrate and amino acid. X-ray diffraction analysis, SEM and TEM were conducted to confirm the formed phases and morphologies. While powders with an uncontrolled shape are obtained through a general oxide-route process, Ca(Sr, Lns)TiO3 powders with micro-sized soft agglomerates consisting of nano-sized primary particles can be prepared using this method.

  14. Open Source Web-Based Solutions for Disseminating and Analyzing Flood Hazard Information at the Community Level

    Science.gov (United States)

    Santillan, M. M.-M.; Santillan, J. R.; Morales, E. M. O.

    2017-09-01

    We discuss in this paper the development, including the features and functionalities, of an open source web-based flood hazard information dissemination and analytical system called "Flood EViDEns". Flood EViDEns is short for "Flood Event Visualization and Damage Estimations", an application that was developed by the Caraga State University to address the needs of local disaster managers in the Caraga Region in Mindanao, Philippines in accessing timely and relevant flood hazard information before, during and after the occurrence of flood disasters at the community (i.e., barangay and household) level. The web application made use of various free/open source web mapping and visualization technologies (GeoServer, GeoDjango, OpenLayers, Bootstrap), various geospatial datasets including LiDAR-derived elevation and information products, hydro-meteorological data, and flood simulation models to visualize various scenarios of flooding and its associated damages to infrastructures. The Flood EViDEns application facilitates the release and utilization of this flood-related information through a user-friendly front end interface consisting of web map and tables. A public version of the application can be accessed at http://121.97.192.11:8082/. The application is currently expanded to cover additional sites in Mindanao, Philippines through the "Geo-informatics for the Systematic Assessment of Flood Effects and Risks for a Resilient Mindanao" or the "Geo-SAFER Mindanao" Program.

  15. Siting low-level radioactive waste in Pennsylvania: socio-political problems and the search for solutions

    International Nuclear Information System (INIS)

    Bord, R.J.

    1987-01-01

    By January 1, 1996 the State of Pennsylvania must take title to and possession of all low-level radioactive waste generated within its borders and pay any damages resulting from failure to provide disposal. While ten years appears to be a comfortable time frame within which to develop a disposal facility, the path to an operating site will undoubtedly be difficult and costly in both time and money. Public opposition to waste in general and to radioactive materials in particular makes the 1996 deadline problematic. The not in my back yard battle cry highlights the conflict characterizing attempts to site any kind of hazardous material. Nuclear power plants, medical facilities, manufacturing industries, and research institutes have a high stake in successful siting. Three issues must be addressed to provide a better understanding of the dilemma facing the State: first, an overview of the development of the present legal situation is necessary to understand the mandate facing Pennsylvania; second, the nature of public intransigence and their perception of the situation sheds light on approaches which may enhance cooperation; finally, probable paths to a LLRW site which are now being discussed in draft legislation provide an assessment of how the State hopes to meet the siting challenge. A discussion of general siting difficulties will conclude the paper

  16. Fine-grain Parallel Processing On A Commodity Platform: A Solution For The Atlas Second-level Trigger

    CERN Document Server

    Boosten, M

    2003-01-01

    From 2005 on, CERN expects to have a new accelerator available for experiments: the Large Hadron Collider (LHC), with a circumference of 27 kilometres. The ATLAS detector produces 40 TeraBytes/s of data. Only a fraction of all data is interesting. A computer system, called the trigger, selects the interesting data through real-time data analysis. The trigger consists of three subsequent filtering levels: LVL1, LVL2, and LVL3. LVL1 will be implemented using special-purpose hardware. LVL2 and LVL3 will be implemented using a Network Of Workstations (NOW). A major problem is to make efficient use of the computing power available in each workstation. The major contribution of this designer's project is an infrastructure named MESH. MESH enables CERN to cost- effectively implement the LVL2 trigger. Furthermore, due to the use of commodity technology, MESH enables the LVL2 trigger to be cost-effectively upgraded and supported during its 20 year lifecycle. MESH facilitates efficient parallel processing on PCs interc...

  17. Water-insoluble fractions of botanical foods lower blood ethanol levels in rats by physically maintaining the ethanol solution after ethanol administration

    Directory of Open Access Journals (Sweden)

    Shunji Oshima

    2015-11-01

    Full Text Available Background: Several studies have analyzed the functions of foods and dietary constituents in the dynamics of alcohol metabolism. However, few studies have reported the function of dietary fibers in the dynamics of alcohol metabolism. Objective: We assessed the effects of botanical foods that contain dietary fibers on alcohol metabolism. Methods: The ability of the water-insoluble fraction (WIF of 18 kinds of botanical foods to maintain 15% (v/v ethanol solution was examined using easily handled filtration. A simple linear regression analysis was performed to examine the correlation between the filtered volumes and blood ethanol concentration (BEC in F344 rats 4 h after the ingestion of 4.0 g/kg of ethanol following dosage of 2.5% (w/v WIF of the experimental botanical foods. Furthermore, the supernatant (6.3 Brix; water-soluble fraction and precipitate (WIF of tomato, with a strong ethanol-maintaining ability, were obtained and BEC and the residual gastric ethanol in rats were determined 2 h after the administration of 4.0 g/kg of ethanol and the individuals fractions. Results: The filtered volumes of dropped ethanol solutions containing all the botanical foods tested except green peas were decreased compared with the ethanol solution without WIF (control. There was a significant correlation between the filtered volumes and blood ethanol concentration (BEC. There was no significant difference in the residual gastric ethanol between controls and the supernatant group; however, it was increased significantly in the WIF group than in controls or the supernatant group. Consistent with this, BEC reached a similar level in controls and the supernatant group but significantly decreased in the WIF group compared with controls or the supernatant group. Conclusions: These findings suggest that WIFs of botanical foods, which are mostly water-insoluble dietary fibers, possess the ability to absorb ethanol-containing solutions, and this ability correlates

  18. Esophageal pH monitoring

    Science.gov (United States)

    pH monitoring - esophageal; Esophageal acidity test ... Esophageal pH monitoring is used to check how much stomach acid is entering the esophagus. It also checks how well the acid is cleared downward into the ...

  19. Evaluating Nanoparticle Sensor Design for Intracellular pH Measurements

    DEFF Research Database (Denmark)

    Benjaminsen, Rikke Vicki; Sun, Honghao; Henriksen, Jonas Rosager

    2011-01-01

    Particle-based nanosensors have over the last decade been designed for optical fluorescent-based ratiometric measurements of pH in living cells. However, quantitative and time-resolved intracellular measurements of pH in endosomes and lysosomes using particle nanosensors is challenging...... and there is a need to improve measurement methodology. In the present paper, we have successfully carried out time resolved pH measurements in endosomes and lyosomes in living cells using nanoparticle sensors and show the importance of sensor choice for successful quantification. We have studied two nanoparticle...... quantification of pH is an unfortunate result when measuring pH too close to the limit of the sensitive range of the sensors. Triple-labeled nanosensors with a pH measurement range of 3.2-7.0, which was synthesized by adding two pH-sensitive fluorophores with different pKa to each sensor, seem to be a solution...

  20. Effect of pH on the structural, optical and morphological properties of Ga-doped ZnO nanoparticles by reflux precipitation method

    Science.gov (United States)

    Ungula, J.; Dejene, B. F.; Swart, H. C.

    2018-04-01

    Gallium-doped zinc oxide nanoparticles (GZO NPs) were synthesized by the reflux precipitation method at 1, 3, 5, 7 and 8 pH conditions of Ga/Zn precursor solution (Ga/Zn sol.). Analysis of X-ray diffraction (XRD) spectra showed that the diffraction peak intensities of GZO NPs increased and the crystallite sizes varied from 11 to 27 nm with an increase in the pH of the Zn/Ga sol. Scanning electron microscopy micrographs showed agglomerated tiny particles that formed on big slabs of nanorods at the lower pH, but fine and enlarged particles on nano-spherical bases formed at the higher pH values. The photoluminescence exciton peak intensities of the GZO NPs and their respective FWHM increased to a maximum at the 5 pH and then reduced slightly as the solution got more basic. The increase of the deep level peak intensities with the increase in the pH followed the XRD diffraction intensity results. It was observed that both the exciton and DLE peaks emission positions shifted to lower wavelengths up to the 5 pH and then red shifted for a further increase in the pH values. The UV-vis analysis also demonstrated that the optical properties of the GZO NPs improved with the increase Ga/Zn sol. pH, as shown by the blue shift of the absorption edge of the reflectance spectra. The band gap energy was tuned from 3.18 to 3.31 eV with the increase in the pH from 1 to 5. An additional increase in the pH yielded no significant change in the optical properties of the GZO NPs.

  1. The PhD by Publication

    Directory of Open Access Journals (Sweden)

    Susi Peacock

    2017-07-01

    Full Text Available Aim/Purpose: The purpose of this work is to develop more nuanced understandings of the PhD by publication, particularly raising awareness of the retrospective PhD by publication. The article aims to contribute to contemporary debates about the differing pathways to the attainment of doctoral study completion and the artifacts submitted for that purpose. It also seeks to support prospective graduate students and supervisors who are embarking upon alternative routes to doctoral accreditation. Background: The PhD is considered the pinnacle of academic study – highly cherished, and replete with deeply held beliefs. In response to changes in job markets, developments in the disciplines, and more varied student cohorts, diverse pathways to completion of this award have emerged, such as the PhD by publication (PhDP. A PhDP may either be prospective or retrospective. For the former, publications are planned and created with their contributions to the PhDP in mind. The retrospective PhD is assembled after some, or most, of the publications have been completed. The artifact submitted for examination in this case consists of a series of peer-reviewed academic papers, books, chapters, or equivalents that have been published or accepted for publication, accompanied by an over-arching narrative. The retrospective route is particularly attractive for professionals who are research-active but lack formal academic accreditation at the highest level. Methodology: This article calls upon a literature review pertaining to the award of PhDP combined with the work of authors who offer their personal experiences of the award. The author also refers to her candidature as a Scottish doctoral student whilst studying for the award of PhD by publication. Contribution: This work raises awareness of the PhDP as a credible and comparable pathway for graduate students. The article focuses upon the retrospective PhDP which, as with all routes to doctoral accreditation, has

  2. Influence of pH on the transport of silver nanoparticles in saturated porous media: laboratory experiments and modeling

    Energy Technology Data Exchange (ETDEWEB)

    Flory, Jason; Kanel, Sushil R., E-mail: sushil.kanel.ctr@afit.edu; Racz, LeeAnn [Air Force Institute of Technology, Department of Systems and Engineering Management (United States); Impellitteri, Christopher A. [U.S. Environmental Protection Agency (United States); Silva, Rendahandi G. [U.S. EPA Test and Evaluation Facility, National Risk Management Research Laboratory, U.S. Environmental Protection Agency, Shaw Environmental and Infrastructure (United States); Goltz, Mark N., E-mail: mark.goltz@afit.edu [Air Force Institute of Technology, Department of Systems and Engineering Management (United States)

    2013-03-15

    Given the ubiquity of silver nanoparticles (AgNPs) and their potential for toxic effects on both humans and the environment, it is important to understand their environmental fate and transport. The purpose of this study is to gain information on the transport properties of commercial AgNP suspensions in a glass bead-packed column under saturated flow conditions at different solution pH levels. Commercial AgNPs were characterized using high-resolution transmission electron microscopy, dynamic light scattering, X-ray photoelectron spectroscopy, ultraviolet visible spectroscopy, Fourier transform infrared spectroscopy, thermogravimetric analysis, and X-ray diffraction. Transport data were collected at different pH levels (4, 6.5, 9, and 11) at fixed ionic strength. Capture of AgNPs increased as the pH of the solution increased from 4 to 6.5. Further increase in pH to 9 and 11 decreased the attachment of AgNPs to the glass beads. AgNP concentration versus time breakthrough data were simulated using an advection-dispersion model incorporating both irreversible and reversible attachment. In particular, a reversible attachment model is required to simulate breakthrough curve tailing at near neutral pH, when attachment is most significant. The laboratory and modeling study reveals that for natural groundwaters, AgNP transport in porous media may be retarded due to capture; but ultimately, most of the mass may be slowly released over time.

  3. pH dependence of the aqueous dissolution rates of perovskite and zirconolite at 90 C

    International Nuclear Information System (INIS)

    McGlinn, P.J.; Hart, K.P.; Loi, E.H.; Vance, E.R.

    1995-01-01

    Perovskite and zirconolite are two of the major phases of the Synroc titanate mineral assemblage. Their aqueous durability under a range of pH conditions at 90 C has been examined. Solution analysis, electron microscopy and X-ray diffraction have been used to investigate the dissolution behavior of these phases, and a perovskite phase doped with Nd, Sr and Al, using buffered solutions at pH levels of 2.1, 3.7, 6.1, 7.9 and 12.9. After 43 days of leaching, Ca and Ti extractions from perovskite and zirconolite show only a weak pH-dependence. SEM investigation of the samples leached at pH 2.1, 6.1 and 12.9 showed that a titanaceous surface layer formed on the perovskite specimens. XRD analysis of the perovskite samples showed that anatase formed on the leached surface at acidic and neutral pHs, but not under alkaline conditions, and that minor amounts of rutile also formed. In the leached perovskite specimens doped with Nd, Sr and Al, no rule was found by XRD and anatase was only detected in the sample leached at pH 2.1. There were no detectable changes in the leached zirconolite samples examined by SEM and XRD

  4. Metal/Metal Oxide Differential Electrode pH Sensors

    Science.gov (United States)

    West, William; Buehler, Martin; Keymeulen, Didier

    2007-01-01

    Solid-state electrochemical sensors for measuring the degrees of acidity or alkalinity (in terms of pH values) of liquid solutions are being developed. These sensors are intended to supplant older electrochemical pH sensors that include glass electrode structures and reference solutions. The older sensors are fragile and subject to drift. The present developmental solid-state sensors are more rugged and are expected to be usable in harsh environments. The present sensors are based on a differential-electrode measurement principle. Each sensor includes two electrodes, made of different materials, in equilibrium with the solution of interest.

  5. Aqueous solutions/nuclear glasses interactions

    International Nuclear Information System (INIS)

    Delage, F.; Advocat, T.; Vernaz, E.; Crovisier, J.L.

    1991-01-01

    Interactions results of the borosilicate glass used in radioactive wastes confinement and aqueous solutions at various temperature and PH show that for the glass components: - the release rate evolution follows an Arrhenius law, - in acid PH, there is a selective dissolution, - in basic PH, there is a stoechiometric dissolution [fr

  6. In vitro synthesis and purification of PhIP-deoxyguanosine and PhIP-DNA oligomer covalent complexes

    Energy Technology Data Exchange (ETDEWEB)

    Freeman, J.

    1994-12-01

    2-Amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) is a heterocyclic amine compound formed when meats are cooked at high temperatures. PhIP damages DNA by forming covalent complexes with DNA carcinogen. In an effort to understand how the binding of PhIP to DNA may cause cancer, it is important to characterize the structures of PhIP-damaged DNA molecules. Our HPLC data support fluorescence and {sup 32}P Post-labeling studies which indicate the formation of several species of 2{prime}deoxyguanosine-(dG) or oligodeoxynucleotide-PhIP adducts. The reaction of PhIP with dG resulted in a reddish precipitate that was likely the major adduct, N-(deoxyguanosin-8-yl)-PhIP (dG-C8-PhIP) adduct, with a more polar adduct fraction remaining in the supernatant. Reversed-phase HPLC analysis of the adducts in the supernatant revealed the existence of species of much shorter retention times than the dG-C8-PhIP adduct, confirming that these species are more polar than dG-C8-PhIP. At least four adducts were formed in the reaction of PhIP with DNA oligomer. HPLC analysis of the PhIP-DNA oligomer supernatant after butanol extractions revealed four unresolved peaks which spectra had maximum wavelengths between 340 and 360 nm. Though adduct peaks were not completely resolved, there was {approximately}3 minutes interval between the DNA oligomer peak and the adduct peaks. Furthermore, fluorescence emission data of the DNA oligomer-PhIP adduct solution show heterogeneous binding. The more polar PhIP adducts were fraction-collected and their structures will be solved by nuclear magnetic resonance or x-ray crystallography.

  7. PH of Hawaiian precipitation: A preliminary report

    International Nuclear Information System (INIS)

    Miller, J.M.; Yoshinaga, A.M.

    1981-01-01

    Daily or biweekly precipitation samples have been collected at various sites on the island of Hawaii since 1974. The elevations of the sites ranged from sea level to 3400 m. Samples were analyzed on the day of collection for pH and conductivity. Detection of major anions, such as sulfate and nitrate, were made on selected samples during the period

  8. Pyrite oxidation at circumneutral pH

    Science.gov (United States)

    Moses, Carl O.; Herman, Janet S.

    1991-02-01

    Previous studies of pyrite oxidation kinetics have concentrated primarily on the reaction at low pH, where Fe(III) has been assumed to be the dominant oxidant. Studies at circumneutral pH, necessitated by effective pH buffering in some pyrite oxidation systems, have often implicitly assumed that the dominant oxidant must be dissolved oxygen (DO), owing to the diminished solubility of Fe(III). In fact, Fe(III)(aq) is an effective pyrite oxidant at circumneutral pH, but the reaction cannot be sustained in the absence of DO. The purpose of this experimental study was to ascertain the relative roles of Fe(III) and DO in pyrite oxidation at circumneutral pH. The rate of pyrite oxidation was first-order with respect to the ratio of surface area to solution volume. Direct determinations of both Fe(II) (aq)> and Fe(III) (aq) demonstrated a dramatic loss of Fe(II) from the solution phase in excess of the loss for which oxidation alone could account. Based on rate data, we have concluded that Fe(II) is adsorbed onto the pyrite surface. Furthermore, Fe(II) is preferred as an adsorbate to Fe(III), which we attribute to both electrostatic and acid-base selectivity. We also found that the rate of pyrite oxidation by either Fe(III) (aq) or DO is reduced in the presence of aqueous Fe(II), which leads us to conclude that, under most natural conditions, neither Fe(III) (aq) nor DO directly attacks the pyrite surface. The present evidence suggests a mechanism for pyrite oxidation that involves adsorbed Fe( II ) giving up electrons to DO and the resulting Fe(III) rapidly accepting electrons from the pyrite. The adsorbed Fe is, thus, cyclically oxidized and reduced, while it acts as a conduit for electrons traveling from pyrite to DO. Oxygen is transferred from the hydration sphere of the adsorbed Fe to pyrite S. The cycle of adsorbed Fe oxidation and reduction and the successive addition of oxygen to pyrite S continues until a stable sulfoxy species dissociates from the surface. Prior

  9. PhD Dissertations

    Directory of Open Access Journals (Sweden)

    Redazione Reti Medievali (a cura di

    2004-06-01

    Full Text Available Report of PhD Dissertations. Francesco Barone Istituzioni, società ed economia a Catania nel tardo medioevo (XIV-XV secolo, Tesi di dottorato in Storia medievale (XVI ciclo, Università degli Studi di Firenze, 2004   Laura Berti Ceroni Il territorio e le strutture di Cesarea e Classe tra tarda antichità e alto medioevo in rapporto con Ravenna, Tesi di dottorato di ricerca in Storia e Informatica, Università degli studi di Bologna, 2002-2003.   Marco Bicchierai Poppi dalla signoria dei conti Guidi al vicariato del Casentino (1360-1480, Tesi di dottorato in Storia medievale (XIV ciclo, Università degli Studi di Firenze, 2004   Emanuela Garimberti Spatiosa ad habitandum loca. Luoghi e identità nella Historia Langobardorum di Paolo Diacono, Tesi di dottorato in Storia medievale (XV ciclo, Università degli Studi di Bologna, 2004   Lorenzo Tanzini Sistemi normativi e pratiche istituzionali a Firenze dalla fine del XIII all’inizio del XV secolo, Tesi di dottorato di ricerca in Storia medievale (XVI ciclo, Università degli Studi di Firenze, 2004   Stefania Tarquini Pellegrinaggio e asseto urbano di Roma, Tesi di dottorato di ricerca in Storia dei centri, delle vie e della cultura dei pellegrinaggi nel Medioevo euro mediterraneo (XV ciclo, Università degli studi di Lecce, 2003

  10. PhD Dissertations

    Directory of Open Access Journals (Sweden)

    Redazione Reti Medievali (a cura di

    2010-06-01

    Full Text Available Report of PhD dissertations. Andrea Brugnoli Una storia locale: l’organizzazione del territorio veronese nel medioevo: trasformazioni della realtà e schemi notarili (IX-metà XII secolo, Tesi di dottorato di ricerca in Scienze Storiche e Antropologiche (XXII ciclo, Università degli Studi di Verona, 2010   Luca Filangieri Famiglie e gruppi dirigenti a Genova (secoli XII-metà XIII, Tesi di dottorato di ricerca in Storia medievale (XXII ciclo, Università degli Studi di Firenze, 2010   Jakub Kujawi ski Wernakularna kolekcja historiograficzna z rękopisu francuskiego nr 688 z Biblioteki Narodowej w Paryżu. Studium źródłoznawcze (La raccolta dei volgarizzamenti delle opere storiografiche nel manoscritto francese 688 della Biblioteca Nazionale di Parigi, Tesi di dottorato, Università “Adam Mickiewicz”, Facoltà di Storia, Pozna, a.a. 2009/2010   Marta Longhi I signori “de Radicata”. Strategie di affermazione familiare e patrimoniale nel Piemonte dei secoli XII-XIV, Tesi di dottorato di ricerca in Istituzioni, Società, Religioni dal Tardo Antico alla fine del Medioevo (XX ciclo, Università di Torino, 2008

  11. PhD Dissertations

    Directory of Open Access Journals (Sweden)

    Redazione Reti Medievali (a cura di

    2003-06-01

    Full Text Available Reporto of PhD Dissertations.   Mario Dalle Carbonare Società, potere e clientele nell’Irlanda altomedievale (secoli V-IX, Tesi di dottorato di ricerca in Storia sociale europea, Università "Ca' Foscari" di Venezia, 2003 Vieri Mazzoni La legislazione antighibellina e la politica oligarchica della Parte Guelfa di Firenze nel secondo Trecento (1347-1378, Tesi di dottorato di ricerca in Storia Medievale (ciclo XII, Università degli Studi di Firenze   Alma Poloni Pisa dalle origini del movimento popolare alla discesa di Ludovico il Bavaro. I gruppi dirigenti cittadini tra continuità e trasformazione, Tesi di dottorato di ricerca in Storia dell'Europa nel medioevo, Università degli studi di Pisa, 2003   Andrea Puglia Potere marchionale, amministrazione del territorio, società locali dalla morte di Ugo di Tuscia a Guelfo VI di Baviera (1001-1160, Tesi di dottorato di ricerca in Storia medievale, Università degli studi di Milano, 2003

  12. Evaluating high pH for control of dreissenid mussels

    Directory of Open Access Journals (Sweden)

    Dave Evans

    2013-04-01

    Full Text Available Two field experiments were carried out using a custom built flow-through laboratory to test the effect of elevated pH on dreissenid musselsas a potential control method. Both experiments tested the ability of dreissenid pediveligers to settle under conditions of elevated pH and thelong-term survival of adult dreissenids under the same conditions. The two experimental sites had different water quality and differentspecies of dreissenids present. The settlement of quagga mussel pediveligers at the lower Colorado River was inhibited with increasing pH.At the maximum achieved pH of 9.1, there was approximately 90% reduction compared to the maximum settlement observed in the controls.Since the settlement was almost as low in pH 8.9 as at pH 9.1, the inhibition in settlement may have been due to the presence of a precipitateformed under high pH conditions rather than the increase in background pH. No mortality of quagga mussel adults was observed in theexperimental pH levels at the lower Colorado River. At San Justo Reservoir, zebra mussel settlement decreased with increasing pH. Newsettlement was almost entirely absent at the highest pH tested (pH 9.6. The observed mortality of adult zebra mussels was low, but did tendto increase with increasing pH. We also tested the response of adult zebra mussels to short-term exposure to very high pH levels (i.e. pH 10,11, and 12. Adult mussels in poor physical condition experienced 90% mortality after 12 hours at pH 12. For unstressed adult zebra mussels,90% mortality was reached after 120 hours at pH 12. Significant mortalities were also observed both at pH 10 and pH 11. From this study,we conclude that pH elevation could be used both as a preventative treatment to eliminate settlement by dreissenid mussels and as an end ofseason treatment to eliminate adults. The high pH treatment would have to be tailored to the site water quality to prevent formation ofprecipitate during treatment and to minimize corrosive

  13. Investigation of the fabrication parameters of thick film metal oxide-polymer pH electrodes

    International Nuclear Information System (INIS)

    Gac, Arnaud

    2002-01-01

    This thesis describes a study into the development of an optimum material and fabrication process for the production of thick film pH electrodes. These devices consist of low cost, miniature and rugged pH sensors formed by screen printing a metal oxide bearing paste onto a high temperature (∼850 deg C) fired metal back contact supported on a standard alumina substrate. The pH sensitive metal oxide layer must be fabricated at relatively low temperatures (<300 deg C) in order to maintain the pH sensitivity of the layer and hence requires the use of a suitably stable low temperature curing binder. Bespoke fabricated inks are derived from a Taguchi style factorial experimental plans in which, different binder types, curing temperatures, hydration level and percentage mixtures of different metal oxides and layer thicknesses were investigated. The pH responses of 18 printed electrodes per batch were assessed in buffer solutions with respect to a commercial reference electrode forming a complete potentiometric circuit. The evaluation criteria used in the study included the device-to-device variation in sensitivity of the pH sensors and their sensitivity variation as a function of time. The results indicated the importance of the choice of binder type in particular on the performance characteristics. Reproducible device-to-device variation in sensitivity was determined for the best inks found, whatever the ink fabrication batch. A reduction in the sensitivity variation with time has been determined using the mathematical models derived from an experimental plan. The lack of reproducibility of the sensitivity magnitude, regardless of the ink manufacturing batch, seems to be a recurrent problem with prototype inks. Experimental sub-Nernstian responses are discussed in the light of possible pH mechanisms. (author)

  14. The influence of pH on the adsorption of lead by Na-clinoptilolite ...

    African Journals Online (AJOL)

    The influence of pH on the adsorption of lead by Na-clinoptilolite: Kinetic and equilibrium studies. ... At high pH of the contact solution, the adsorption process occurs by ion exchange and at low pH; i.e., it is physical. The variation of the Gibbs free energy demonstrates that adsorption occurs spontaneously. The process was ...

  15. Intracellular pH in rat pancreatic ducts

    DEFF Research Database (Denmark)

    Novak, I; Hug, M; Greger, R

    1997-01-01

    In order to study the mechanism of H+ and HCO3- transport in a HCO3- secreting epithelium, pancreatic ducts, we have measured the intracellular pH (pHi) in this tissue using the pH sensitive probe BCECF. We found that exposures of ducts to solutions containing acetate/acetic acid or NH4+/NH3...... buffers (20 mmol/l) led to pHi changes in accordance with entry of lipid-soluble forms of the buffers, followed by back-regulation of pHi by duct cells. In another type of experiment, changes in extracellular pH of solutions containing HEPES or HCO3-/CO2 buffers led to significant changes in pHi that did....... Under some conditions, these exchangers can be invoked to regulate cell pH....

  16. Effect of fluoridated varnish and silver diamine fluoride solution on enamel demineralization: pH-cycling study Efeito do verniz fluoretado e da solução de diamino fluoreto de prata na desmineralização do esmalte: estudo utilizando modelo de ciclagem de pH

    Directory of Open Access Journals (Sweden)

    Alberto Carlos Botazzo Delbem

    2006-04-01

    Full Text Available OBJECTIVE: In the present investigation, the anticariogenic effect of fluoride released by two products commonly applied in infants was evaluated. METHODS: Bovine sound enamel blocks were randomly allocated to each one of the treatment groups: control (C, varnish (V and diamine silver fluoride solution (D. The blocks were submitted to pH cycles in an oven at 37ºC. Next, surface and cross-sectional microhardness were assessed to calculate the percentage loss of surface microhardness (%SML and the mineral loss (deltaZ. The fluoride present in enamel was also determined. RESULTS: F/Px10-3 (ANOVA, pOBJETIVOS: Este trabalho avaliou o efeito anticariogênico do flúor liberado por dois produtos comumente aplicados em crianças. MÉTODOS: Para isto, utilizaram-se blocos de esmalte de dentes bovinos distribuídos aleatoriamente em três grupos de tratamento: controle (C, verniz fluoretado (V e solução de diamino fluoreto de prata (D. Os blocos foram submetidos à ciclagem de pH a 37ºC. Após, realizou-se o teste de microdureza de superfície (para o cálculo da % da perda de microdureza de superfície - %SML e em secção longitudinal do esmalte (% de alteração da área mineral - %deltaZ e a determinação do flúor presente no esmalte (F/P x 10-3. RESULTADOS: As concentrações de flúor (ANOVA, p<0,05 na 1ª camada do esmalte, antes da ciclagem de pH, foram (C, V e D: 1,6ª; 21,6b e 4,0c. Os resultados de %SML (Kruskal-Wallis, p<0.05 foram: -64,0ª, -45,2b e -53,1c. Os valores de %deltaZ (ANOVA, p<0.05 foram: -18,7ª, -7,7b e -17,3ª. CONCLUSÃO: Os dados sugerem que o flúor liberado pelo verniz apresentou maior interação com o esmalte promovendo menor perda mineral quando comparado à solução de diamino de prata.

  17. Influence of different levels of aluminum on the development of citrus rootstock swingle citrumelo (Citrus paradisi mcf. x Poncirus trifoliata raf. in nutrient solution

    Directory of Open Access Journals (Sweden)

    Carlos Henrique dos Santos

    2000-01-01

    Full Text Available This work aimed at evaluating the influence of different levels of aluminum on the physiological parameters of the citrus rootstock Swingle Citrumelo in hydroponic solution. The experiment was carried out with a completely randomized design with three replications, subdivided in several lots. The levels of aluminum used were: 0, 7.5, 15, 22.5 and 30 mg L-1 in form of AlCl3.6H2O in nutrient solution. Following physiological parameters were evaluated: specific and relative foliar area, relative foliar mass, and the ratio of aerial part dry matter/root system dry matter. The results showed that aluminum did not influence the parameters evaluated except the specific foliar area, which decreased starting at the 7.5 mg L-1 level.O presente trabalho teve como objetivo avaliar a influência de diferentes níveis de alumínio nos parâmetros fisiológicos do porta-enxerto cítrico citrumeleiro Swingle em cultivo hidropônico. O experimento foi conduzido seguindo o delineamento estatístico inteiramente casualizado, com 3 repetições, em parcelas subdivididas. Os níveis de alumínio utilizados foram: 0, 7,5, 15, 22,5 e 30 mg L-1, na forma de AlCl3 6.H2O em solução nutritiva. Foram avaliados os parâmetros fisiológicos área foliar específica, razão de área foliar e massa foliar, relação matéria seca da parte aérea/matéria seca do sistema radicular. De acordo com os resultados obtidos nestas condições, conclui-se que os níveis de alumínio não influenciaram nos valores dos parâmetros acima discutidos, excetuando-se a AFE, havendo decréscimos destes valores a partir de 7,5 mg L-1 de alumínio.

  18. Building a comprehensive mill-level database for the Industrial Sectors Integrated Solutions (ISIS) model of the U.S. pulp and paper sector.

    Science.gov (United States)

    Modak, Nabanita; Spence, Kelley; Sood, Saloni; Rosati, Jacky Ann

    2015-01-01

    Air emissions from the U.S. pulp and paper sector have been federally regulated since 1978; however, regulations are periodically reviewed and revised to improve efficiency and effectiveness of existing emission standards. The Industrial Sectors Integrated Solutions (ISIS) model for the pulp and paper sector is currently under development at the U.S. Environmental Protection Agency (EPA), and can be utilized to facilitate multi-pollutant, sector-based analyses that are performed in conjunction with regulatory development. The model utilizes a multi-sector, multi-product dynamic linear modeling framework that evaluates the economic impact of emission reduction strategies for multiple air pollutants. The ISIS model considers facility-level economic, environmental, and technical parameters, as well as sector-level market data, to estimate the impacts of environmental regulations on the pulp and paper industry. Specifically, the model can be used to estimate U.S. and global market impacts of new or more stringent air regulations, such as impacts on product price, exports and imports, market demands, capital investment, and mill closures. One major challenge to developing a representative model is the need for an extensive amount of data. This article discusses the collection and processing of data for use in the model, as well as the methods used for building the ISIS pulp and paper database that facilitates the required analyses to support the air quality management of the pulp and paper sector.

  19. Building a Comprehensive Mill-Level Database for the Industrial Sectors Integrated Solutions (ISIS) Model of the U.S. Pulp and Paper Sector

    Science.gov (United States)

    Modak, Nabanita; Spence, Kelley; Sood, Saloni; Rosati, Jacky Ann

    2015-01-01

    Air emissions from the U.S. pulp and paper sector have been federally regulated since 1978; however, regulations are periodically reviewed and revised to improve efficiency and effectiveness of existing emission standards. The Industrial Sectors Integrated Solutions (ISIS) model for the pulp and paper sector is currently under development at the U.S. Environmental Protection Agency (EPA), and can be utilized to facilitate multi-pollutant, sector-based analyses that are performed in conjunction with regulatory development. The model utilizes a multi-sector, multi-product dynamic linear modeling framework that evaluates the economic impact of emission reduction strategies for multiple air pollutants. The ISIS model considers facility-level economic, environmental, and technical parameters, as well as sector-level market data, to estimate the impacts of environmental regulations on the pulp and paper industry. Specifically, the model can be used to estimate U.S. and global market impacts of new or more stringent air regulations, such as impacts on product price, exports and imports, market demands, capital investment, and mill closures. One major challenge to developing a representative model is the need for an extensive amount of data. This article discusses the collection and processing of data for use in the model, as well as the methods used for building the ISIS pulp and paper database that facilitates the required analyses to support the air quality management of the pulp and paper sector. PMID:25806516

  20. The increase in pH during aging of porous sol-gel silica spheres

    NARCIS (Netherlands)

    Titulaer, M.K.; Kegel, W.K.; Jansen, J.B.H.; Geus, John W.

    1994-01-01

    The increase in pH in the hydrothermal fluid is studied after hydrothermal aging of porous silica gel spheres of 1–3 mm diameter. The porous silica spheres are formed by the sol-gel process from a supersaturated silica solution. The increase of the pH of the hydrothermal solution affects the silica

  1. Solution mining process

    International Nuclear Information System (INIS)

    Showalter, W.E.

    1984-01-01

    A solution mining process which may be used for uranium, thorium, vanadium, copper, nickel, molybdenum, rhenium, and selenium is claimed. During a first injection-and-production phase of between 6 months and 5 years, a leaching solution is injected through at least one well into the formation to solubilize the mineral values and form a pregnant liquor. This liquor is recovered through another well. The leaching solution contains sulfuric acid, nitric acid, hydrochloric acid, carbonic acid, an alkali metal carbonate, an alkali metal bicarbonate, ammonium carbonate or ammonium bicarbonate. Subsequently during a first production-only phase of between about 2 weeks and one year, injection of the leaching solution is suspended but pregnant liquor is still recovered. This stage is followed by a second injection-and-production phase of between 6 months and 5 years and a second production-only phase. The mineral values are separated from the pregnant liquor to form a barren liquor. The leaching agent is introduced into this liquor, and the solution is recycled. In a second claim for the solution mining of uranium, dilute carbonic acid is used as the leaching solution. The solution has a pH less than 7 and a bicarbonate ion concentration between about 380 ppm and 1000 ppm. The injection-and-production phase lasts between one and two years and the production only phase takes between one and four months. Carbon dioxide is introduced into the barren liquor to form a dilute carbonic acid solution and the solution is recycled

  2. Effect of pH on the complexation of kaempferol-4'-glucoside with three β-cyclodextrin derivatives: isothermal titration calorimetry and spectroscopy study.

    Science.gov (United States)

    Zheng, Yan; Dong, Li-Na; Liu, Min; Chen, Aiju; Feng, Shangcai; Wang, Bingquan; Sun, Dezhi

    2014-01-08

    The utilization of kaempferol and its glycosides in food and pharmaceutical industries could be improved by the formation of inclusion complexes with cyclodextrins at different pH. This study explores the complexation of kaempferol-4'-glucoside with sulfobutyl ether-β-cyclodextrin (SBE-β-CD), hydroxypropyl-β-cyclodextrin (HP-β-CD), and methylated-β-cyclodextrin (M-β-CD) in phosphate buffer solutions of different pH using isothermal titration calorimetry, UV-vis absorption and proton nuclear magnetic resonance spectroscopy at 298.2 K. Experimental results showed that kaempferol-4'-glucoside binds with the three β- cyclodextrins in the same 1:1 stoichiometry. The rank order of stability constants is SBE-β-CD > HP-β-CD > M-β-CD at the same pH level and pH 6.0 > pH 7.4 > pH 9.0 for the same cyclodextrin. The binding of kaempferol-4'-glucoside with the three β-cyclodextrin derivatives is synergistically driven by enthalpy and entropy at pH 6.0 and enthalpy-driven at pH 7.4 and 9.0. The possible inclusion mode was that in the cavity of β-CD is included the planar benzopyranic-4-one part of the kaempferol-4'-glucoside.

  3. pH tolerance of Daphnia pulex (leydig, emend. , richard)

    Energy Technology Data Exchange (ETDEWEB)

    Davis, P; Ozburn, G W

    1969-01-01

    The survival time and reproduction of female Daphnia pulex in solutions varying in pH have been observed. Dilute sodium hydroxide or sulfuric acid solutions were added to four different diluent waters: distilled water, aerated tap water, aerated and filtered tap water from an aquarium containing Dace minnows, and Mcintyre River water. D. Pulex (initially up to 72 hours old) survived for the duration of the experiment (32 hours) in river water within a pH range of 6.1 to 10.3; in aquarium water within a pH range of 4.3 to 10.4; only at pH 6.4 and pH 7.6 in distilled water; and in none of the solutions using aerated tap water. The dissolved oxygen content was measured at the beginning and end of every experiment and was found never to fall below 6.2 p.p.M. Those individuals which survived were cultured in the laboratory and parthenogenesis was observed at pH values between 7.0 and 8.7.

  4. FLEXIBLE PH SENSOR WITH POLYANILINE LAYER BASED ON IMPEDANCE MEASUREMENT

    OpenAIRE

    Chuang, Cheng-Hsin; Wu, Hsun-Pei; Chen, Cheng-Ho; Wu, Peng-Rong

    2012-01-01

    A flexible sensor with conducting polyaniline layer for detecting pH value based on the impedance measurement is fabricated and demonstrated in this study. The pH sensor consists of an interdigital electrode array on a flexible printed circuit and a thin-film polyaniline as the sensing layer. As the conductivity of polyaniline depends on the redox state, the impedance change of the polyaniline after it has reacted with different pH value solutions works as the sensing mechanism. In order to o...

  5. Effect of pH on Pulp Potential and Sulphide Mineral Flotation

    OpenAIRE

    GÖKTEPE, Ferihan

    2014-01-01

    Control of pH is one of the most widely applied methods for the modulation of mineral flotation. In this study the effect of pH on potential in solution and sulphur minerals flotation is discussed with various electrodes. The electrodes were platinum, gold, chalcopyrite, pyrite and galena. In solution, potentials were linearly dependent on pH with a different slope for each electrode. Chalcopyrite, pyrite, sphalerite and galena minerals flotation tests were performed in a microflot...

  6. Ratiometric detection of pH fluctuation in mitochondria with a new fluorescein/cyanine hybrid sensor? ?Electronic supplementary information (ESI) available: Characterization of Mito-pH, emission spectra and photograph of Mito-pH solutions, linear fitting of the ratiometric response, and co-localization images at pH 8.50. See DOI: 10.1039/c4sc04021j Click here for additional data file.

    OpenAIRE

    Chen, Yuncong; Zhu, Chengcheng; Cen, Jiajie; Bai, Yang; He, Weijiang; Guo, Zijian

    2015-01-01

    The homeostasis of mitochondrial pH (pHm) is crucial in cell physiology. Developing small-molecular fluorescent sensors for the ratiometric detection of pHm fluctuation is highly demanded yet challenging. A ratiometric pH sensor, Mito-pH, was constructed by integrating a pH-sensitive FITC fluorophore with a pH-insensitive hemicyanine group. The hemicyanine group also acts as the mitochondria targeting group due to its lipophilic cationic nature. Besides its ability to target mitochondria, thi...

  7. PH-Induced Nanosegregation of Ritonavir to Lyotropic Liquid Crystal of Higher Solubility Than Crystalline Polymorphs

    International Nuclear Information System (INIS)

    Rodriguez-Spong, B.; Acciacca, A.; Fleisher, D.; Rodriguez-Hornedo, N.

    2009-01-01

    Birefringent spherical vesicles of ritonavir (RTV) are formed by increasing the pH of aqueous solutions from 1 to 3 or to 7 and by addition of water to ethanol solutions at room temperature. Increasing the pH creates supersaturation levels of 30--400. Upon this change in pH, the solutions become translucent, implying that some kind of RTV assembly was formed. Small spherical vesicles of narrow size distribution are detectable only after a few hours by optical microscopy. The vesicles show similar X-ray diffraction patterns and differential scanning calorimetry (DSC) behavior to amorphous RTV prepared by melt-quenching crystalline RTV. Examination by polarized optical microscopy suggests that these are lyotropic liquid crystalline (LLC) assemblies. Small-angle X-ray scattering and synchrotron X-ray diffraction further support the presence of orientational order that is associated with a nematic structure. RTV self-organizes into various phases as a result of the supersaturation created in aqueous solutions. The LLC vesicles do not fuse but slowly transform to the polymorphs of RTV (in days), Form I and finally Form II. Amorphous RTV in aqueous suspension also undergoes a transformation to a mesophase of similar morphology. Transformation pathways are consistent with measured dissolution rates and solubilities: amorphous > LLC >> Form I > Form II. The dissolution and solubility of LLC is slightly lower than that of the amorphous phase and about 20 times higher than that of Form II. RTV also self-assembles at the air/water interface as indicated by the decrease in surface tension of aqueous solutions. This behavior is similar to that of amphiphilic molecules that induce LLC formation.

  8. A PhD is a PhD is a PhD

    OpenAIRE

    Ostrow, Deborah Anne

    2017-01-01

    A PhD is a PhD is a PhD is a practice-based project that interrogates the process of an artist undertaking PhD research under established criteria. It consists of an exegesis, an original screenplay, and a digital film made for online viewing, with images drawn from a range of documentaries and films found on YouTube. They have been dissected, re-assembled and then re-embedded to YouTube. The source material covers topics such as medicalization of madness, the conspicuous appropriation of uni...

  9. PhD on Track – designing learning for PhD students

    Directory of Open Access Journals (Sweden)

    Gunhild Austrheim

    2013-12-01

    Full Text Available Three years ago we started the project "Information Management for Knowledge Creation". The project was initiated to create online information literacy modules for PhD students. The result of our endeavours, PhD on Track, will be launched in May 2013. The initial stage of the project was mapping out the information behaviour of PhD students, as well as what services they require from the library through a literature review and a focus group study. The findings of these inquiries formed the knowledge base from which we developed our information literacy modules. Our paper will focus on the interaction between content production and user testing when creating PhD on Track. Methods: User testing has been employed throughout the production stage. We have tested navigation and organisation of the web site, content and usability. The project team have conducted expert testing. Analysis: The results from our user testing have played an important part in decisions concerning content production. Our working hypothesis was that the PhD students would want an encyclopaedic website, a place to quickly find answers. However, the user tests revealed that PhD students understood and expected the website to be learning modules. Conclusions: The PhD students in the tests agreed that a site such as this would be useful, especially to new PhD students. They also liked the design, but had some qualms with the level of information. They preferred shorter text, but with more depth. The students would likewise have preferred more practical examples, more illustrations and more discipline specific information. The current content of PhD on Track reflects the feedback from the user testing. We have retained initial ideas such as one section for reviewing and discovering research literature and one section for publishing PhD research work. In addition, we have included more practical examples to indicate efficient workflows or relevant actions in context. Illustrations

  10. Evaluation of the electrochemical behavior of U{sub 2.5}Zr{sub 7.5}Nb and U{sub 3}Zr{sub 9}Nb uranium alloys in relation to the pH and the solution aeration

    Energy Technology Data Exchange (ETDEWEB)

    Mansur, Fabio Abud; Santos, Ana Maria Matildes dos; Ferraz, Wilmar Barbosa; Figueiredo, Celia de Araujo, E-mail: ferraz@cdtn.b [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN/CNEN-MG), Belo Horizonte, MG (Brazil)

    2011-07-01

    The Centro de Desenvolvimento da Tecnologia Nuclear (CDTN) is developing, in cooperation with the Centro Tecnologico da Marinha (CTMSP), the advanced nuclear plate type fuel for the second core of the land-based reactor prototype of the Laboratorio de Geracao Nucleo-Eletrica (LABGENE). Recent investigations have shown that the fuel made of uranium-based niobium and zirconium alloys reaches the best performance relative to other fuels, e.g. UO{sub 2}. Niobium and Zirconium also increase the corrosion resistance and the mechanical strength of the uranium alloys. By means of electrochemical techniques the corrosion behavior of alloys U{sub 2}.{sub 5}Zr{sub 7.5}Nb and U{sub 3}Zr{sub 9}Nb, developed at CDTN and heat treated in the temperature range of 200 deg C to 600 deg C, was assessed. The effect of the parameters pH and solution aeration was studied as well as the influence of zirconium and niobium alloying elements in the corrosion of uranium. The techniques used were open circuit potential, electrochemical impedance and potentiodynamic anodic polarization at room temperature. The tests were performed in a three-electrode electrochemical cell with Ag/AgCl (3M KCl) as the reference electrode and a platinum plate as the auxiliary electrode. The potentiodynamic polarization curves of uranium and its alloys in acidic solutions showed regions with anodic currents limited by a passive film. The presence of niobium and zirconium contributed for the formation of this film. The impedance data showed the presence of two semicircles in the Bode diagram, indicating the occurrence of two distinct electrochemical processes. The data were fitted to an equivalent circuit model in order to obtain parameters of the electrochemical processes and evaluate the effect of the studied variables. (author)

  11. OPC Paste Samples Exposed To Aggressive Solutions. Cementitious Barriers Partnership

    Energy Technology Data Exchange (ETDEWEB)

    Langton, C. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

    2014-11-01

    The study presented in this report focused on a low-activity wasteform containing a high-pH pore solution with a significant level of sulfate. The purpose of the study was to improve understanding of the complex concrete/wasteform reactive transport problem, in particular, the role of pH in sulfate attack. Paste samples prepared at three different water-to-cement ratios were tested. The mixtures were prepared with ASTM Type I cement, without additional admixtures. The samples were exposed to two different sodium sulfate contact solutions. The first solution was prepared at 0.15M Na2SO4. The second solution also incorporated 0.5M NaOH, to mimic the high pH conditions found in Saltstone. The data collected indicated that, in Na2SO4 solution, damage occurs to the pastes. In the case of the high-pH sulfate solution (Na2SO4 + NaOH), no signs of damage were observed on any of the paste mixtures. These results indicate that the high sulfate content found in the wasteform pore solution will not necessarily lead to severe damage to concrete. Good-quality mixtures could thus prove durable over the long term, and act as an effective barrier to prevent radionuclides from reaching the environment.

  12. Effect of pH on turbidity, size, viscosity and the shape of sodium caseinate aggregates with light scattering and rheometry.

    Science.gov (United States)

    Ghorbani Gorji, Sara; Ghorbani Gorji, Elham; Mohammadifar, Mohammad Amin

    2015-03-01

    The characterization of sodium caseinate solutions as a function of pH was determined using titration with HCL through turbidimetry in different concentrations (0.03 wt.%, 0.045 wt.%, 0.06 wt.%, 0.09 wt.%, 0.2 wt.%, and 0.3 wt.%). Additionally, the coupling of slow in situ acidification of the solution and rheometry was utilized to gain deeper insights into pH-induced structural transitions during the self assembly process and particle size distribution analysis have been used to determine the behavior of sodium caseinate solutions in different pHs. The formation of aggregates during the acidification process was clearly visualized using microscopy. Surprisingly the viscosity of sodium caseinate solution at pH 4.64 was maximum and decreased by lowering pH. Particle size analysis confirmed the onset of big aggregates on decreasing pH but further acidification led to formation of smaller aggregates. A small concentration effect on pI was seen where at sodium caseinate levels of 0.03 wt.% the pI occurred at 4.29, where at sodium caseinate levels of 0.30 wt.% pI value was 4.64.

  13. Decoloration and mineralization of aqueous solution of cationic (basic) dye Astrazon Black FDL by using gamma rays

    International Nuclear Information System (INIS)

    Kantoglu, Oemer

    2017-01-01

    Degree of decolorization due to the irradiation of aqueous solutions of commercial cationic (basic) Astrazon Black FDL textile dye was studied in this study. Factor effecting radiolysis of the dye such as dye concentration, absorbed dose, toxicity, COD, BOD_5 and pH of solutions were studied at air, O_2 saturated and H_2O_2 environments. Unirradiated Astrazon Black FDL was non-biodegradable, whereas it was biodegradable after irradiation. The biodegradability (BOD_5/COD) increased at 2 kGy for Astrazon Black FDL in all solutions. The biorefractory organic compounds were converted into more easily biodegradable compounds having lower molecular weights. In optimum dose and pH determination experiments, 5 kGy pH 12 at air, 7 kGy pH 3 at O_2 saturated, 9 kGy pH 3 at 2.6 mM H_2O_2 for Astrazon Black FDL were found as the optimum irradiation conditions. Toxicity level of unirradiated solutions was high, whereas toxicity level of irradiated solutions was lower.

  14. Decoloration and mineralization of aqueous solution of cationic (basic) dye Astrazon Black FDL by using gamma rays

    Energy Technology Data Exchange (ETDEWEB)

    Kantoglu, Oemer [Turkish Atomic Energy Authority, Ankara (Turkey). Saraykoey Nuclear Research and Training Center

    2017-06-01

    Degree of decolorization due to the irradiation of aqueous solutions of commercial cationic (basic) Astrazon Black FDL textile dye was studied in this study. Factor effecting radiolysis of the dye such as dye concentration, absorbed dose, toxicity, COD, BOD{sub 5} and pH of solutions were studied at air, O{sub 2} saturated and H{sub 2}O{sub 2} environments. Unirradiated Astrazon Black FDL was non-biodegradable, whereas it was biodegradable after irradiation. The biodegradability (BOD{sub 5}/COD) increased at 2 kGy for Astrazon Black FDL in all solutions. The biorefractory organic compounds were converted into more easily biodegradable compounds having lower molecular weights. In optimum dose and pH determination experiments, 5 kGy pH 12 at air, 7 kGy pH 3 at O{sub 2} saturated, 9 kGy pH 3 at 2.6 mM H{sub 2}O{sub 2} for Astrazon Black FDL were found as the optimum irradiation conditions. Toxicity level of unirradiated solutions was high, whereas toxicity level of irradiated solutions was lower.

  15. Behavior of technetium in alkaline solution: Identification of non-pertechnetate species in high-level nuclear waste tanks at the Hanford reservation

    International Nuclear Information System (INIS)

    Lukens, Wayne W. Jr.; Shuh, David K.; Schroeder, Norman C.; Ashley, Kenneth R.

    2003-01-01

    Technetium is a long-lived (99Tc: 213,000 year half-life) fission product found in nuclear waste and is one of the important isotopes of environmental concern. The known chemistry of technetium suggests that it should be found as pertechnetate, TcO4-, in the extremely basic environment of the nuclear waste tanks at the Hanford site. However, other chemical forms of technetium are present in significant amounts in certain tanks, and these non-pertechnetate species complicate the treatment of the waste. The only spectroscopic characterization of these non-pertechnetate species is a series of X-ray absorption near edge structure (XANES) spectra of actual tank waste. To better understand the behavior of technetium under these conditions, we have investigated the reduction of pertechnetate in highly alkaline solution in the presence of compounds found in high-level waste. These results and the X-ray absorption fine structure (XAFS) spectra of these species are compared to the chemical behavior and XANES spectra of the actual non-pertechnetate species. The identity of the nonpertechnetate species is surprising

  16. Effects of Iron Concentration Level in Extracting Solutions from Contaminated Soils on the Determination of Zinc by Flame Atomic Absorption Spectrometry with Two Background Correctors

    Directory of Open Access Journals (Sweden)

    Christophe Waterlot

    2012-01-01

    Full Text Available Zinc and iron concentrations were determined after digestion, water, and three-step sequential extractions of contaminated soils. Analyses were carried out using flame absorption spectrometry with two background correctors: a deuterium lamp used as the continuum light source (D2 method and the high-speed self-reversal method (HSSR method. Regarding the preliminary results obtained with synthetic solutions, the D2 method often emerged as an unsuitable configuration for compensating iron spectral interferences. In contrast, the HSSR method appeared as a convenient and powerful configuration and was tested for the determination of zinc in contaminated soils containing high amounts of iron. Simple, fast, and interference-free method, the HSSR method allows zinc determination at the ppb level in the presence of large amounts of iron with high stability, sensitivity, and reproducibility of results. Therefore, the HSSR method is described here as a promising approach for monitoring zinc concentrations in various iron-containing samples without any pretreatment.

  17. Selective separation of cesium from simulated high level liquid waste solution using 1,3-dioctyloxy calix[4]arene-benzo-crown-6

    International Nuclear Information System (INIS)

    Vikas Kumar; Sharma, J.N.; Hubli, R.C.

    2014-01-01

    The 25,27-di(octyloxy)calix[4]arenebenzocrown-6 (CBC) in 1,3-alternate conformation was synthesized indigenously starting from its intermediates in good yield and purity. The extraction studies of CBC were carried out by using two different phase modifiers namely isodecyl alcohol and ortho-nitrophenyl hexyl ether. Detailed investigations on the effect of various parameters like, concentration of phase modifiers, aqueous phase acidity, ligand concentration, nitrate ion concentration and effect of temperature on extraction of cesium have been carried out. The concentration of phase modifiers was optimized to be 30 % in n-dodecane to ensure optimum extraction of cesium. Stoichiometry of the extracted complex determined by slope analysis method reveals 1:1:1 molar ratio for CsNO 3 :CBC:HNO 3 . The extraction process was found to be exothermic as determined from the plot of log K ex versus 1/T. The solvent system with a composition 0.01 M CBC/30 % phase modifier/n-dodecane was found to be effective for selective separation of cesium from simulated high level liquid waste solution. (author)

  18. The diffusion behaviour of hydrogen in a low alloyed carbon steel with respect to the deformation level and to the passivation process in alkaline solutions

    International Nuclear Information System (INIS)

    Juilfs, G.G.

    2001-01-01

    The diffusion behaviour of hydrogen in a low alloyed carbon steel with respect to the deformation level and to the passivation process in alkaline solutions. The influence of plastic strain on the diffusion behaviour of hydrogen in a low alloyed structural steel (FeE 690T) was investigated using the electrochemical permeation technique. The plastic deformation was introduced either by cold rolling or by tensile straining. Specially prepared C(T)-specimen enabled the direct determination of the diffusion coefficient in the highly deformed region ahead of a blunting crack. It was shown, that the apparent diffusion coefficient depends on the plastic strain and on the overall hydrogen concentration, whereas the maximum hydrogen flux remained almost unchanged. These observations are interpreted in terms of variations in the dislocation density, which act as 'sinks' for the diffusable hydrogen atoms. The results are compared with model calculations, that describe the hydrogen transport as a function of the trap density. The comparison of the numerical simulation and the experimental data shows a good agreement over the whole range of plastic strain levels, leading to a trap density of 6.1.10 19 /d 3 . Together with the results of a previous study on the fracture toughness of FeE 690T in the presence of hydrogen the permeation data obtained in this work suggest that the observed influence of deformation rates on the fracture mechanism can be attributed to the reduced mobility of hydrogen atoms in the plastic zone. The assumption that the hydrogen transport during monotonic straining is controlled by diffusion was confirmed by investigations concerning the formation of surface films. Using a potentiodynamic method (cyclovoltammetry) a characterisation of the surface reactions involved in permeation experiments was performed. It was shown that the nature of the passive layers forming on the surface depends on the applied potential, affecting mainly the hydrogen absorption

  19. Recovery of thorium along with uranium 233 from Thorex waste solution employing Chitosan

    International Nuclear Information System (INIS)

    Priya, S.; Reghuram, D.; Kumaraguru, K.; Vijayan, K.; Jambunathan, U.

    2003-01-01

    The low level waste solution, generated from Thorex process during the processing of U 233 , contains thorium along with traces of Th 228 and U 233 . Chitosan, a natural bio-polymer derived from Chitin, was earlier used to recover the uranium and americium. The studies were extended to find out its thorium sorption characteristics. Chitosan exhibited very good absorption of thorium (350 mg/g). Chitosan was equilibrated directly with the low level waste solution at different pH after adjusting its pH, for 60 minutes with a Chitosan to aqueous ratio of 1:100 and the raffinates were filtered and analysed. The results showed more than 99% of thorium and U 233 could be recovered by Chitosan between pH 4 and 5. Loaded thorium and uranium could be eluted from the Chitosan by 1M HNO 3 quantitatively. (author)

  20. Continuous pH monitoring in a perfused bioreactor system using an optical pH sensor

    Science.gov (United States)

    Jeevarajan, Antony S.; Vani, Sundeep; Taylor, Thomas D.; Anderson, Melody M.

    2002-01-01

    Monitoring and regulating the pH of the solution in a bioprocess is one of the key steps in the success of bioreactor operation. An in-line optical pH sensor, based on the optical absorption properties of phenol red present in the medium, was developed and tested in this work for use in NASA space bioreactors based on a rotating wall-perfused vessel system supporting a baby hamster kidney (BHK-21) cell culture. The sensor was tested over three 30-day and one 124-day cell runs. The pH sensor initially was calibrated and then used during the entire cell culture interval. The pH reported by the sensor was compared to that measured by a fiber optically coupled Shimadzu spectrophotometer and a blood gas analyzer. The maximum standard error of prediction for all the four cell runs for development pH sensor against BGA was +/-0.06 pH unit and for the fiber optically coupled Shimadzu spectrophotometer against the blood gas analyzer was +/-0.05 pH unit. The pH sensor system performed well without need of recalibration for 124 days. Copyright 2002 Wiley Periodicals, Inc.

  1. pH relationship and nutrient availability for cacao in an Entisol from the Colombian Amazon

    Directory of Open Access Journals (Sweden)

    Gelber Rosas-Patiño

    2017-09-01

    Full Text Available Liming is a common practice in acid soil manage-ment; however, the information on liming in cacao soils of the Colombian Amazon region is precarious. Incubation curves were built in a highly acid Typic Udorthents cultivated with cacao (Theobroma cacao L. - Malvaceae, for which increasing doses (0 - 1 - 3 - 5 - 7 - 9 -11 Mg/ha of dolomite lime (Ca M g (CO32 and calcium carbonate (CaCO3 were used, in order to establish the type and amount of liming material (ME with better reactivity, and the one that is better favored with the acidity changes: pH, Al3+, H+, total acidity. Models to estimate the ME dose needed to manage the soil in order to obtain the desired pH (≥5.5 were generated. Sub-sequently, the soil was then limed under field conditions and pH, Al3+, Al in solution (Alsol, aluminum saturation (SAI, cation exchange capacity (CEC and N, P, K, Ca, Mg, Zn, Cu, B, Fe and Mn availability were evaluated. The results show that the greatest reaction of liming materials in these soils occurs after 60 days; applications of 7 Mg/ha allowed to raise the pH from 5.5 to 6.0 and decreases Al and Fe levels. These changes improved the CECand nutrient availability (Ca, Mg, P, Zn for cacao without affecting other nutrients such as N and K.

  2. Influence of radiopacifying agents on the solubility, pH and antimicrobial activity of portland cement.

    Science.gov (United States)

    Weckwerth, Paulo Henrique; Machado, Adriano Cosme de Oliveira; Kuga, Milton Carlos; Vivan, Rodrigo Ricci; Polleto, Raquel da Silva; Duarte, Marco Antonio Hungaro

    2012-01-01

    The aim of this study was to evaluate the interference of the radiopacifiers bismuth oxide (BO), bismuth carbonate (BC), bismuth subnitrate (BS), and zirconiun oxide (ZO) on the solubility, alkalinity and antimicrobial properties of white Portland cement (WPC). The substances were incorporated to PC, at a ratio of 1:4 (v/v) and subjected to a solubility test. To evaluate the pH, the cements were inserted into retrograde cavities prepared in simulated acrylic teeth and immediately immersed in deionized water. The pH of the solution was measured at 3, 24, 72 and 168 h. The antimicrobial activity was evaluated by a radial diffusion method against the microorganisms S. aureus (ATCC 25923), P. aeruginosa (ATCC 27853), E. faecalis (ATCC 29212) and C. albicans (ATCC 10231). The zone of microbial growth inhibition was measured after 24 h. The addition of BS and BC increased the solubility of the cement. The pH values demonstrated that all materials produced alkaline levels. At 3 h, BS showed lower pH than WPC (p0.05). The materials did not present antimicrobial activity for S. aureus, P. aeruginosas and E. faecalis (p>0.05). With regards to C. albicans, all materials formed an inhibition zone, mainly the mixture of WPC with ZO (p<0.05). The type of radiopacifier incorporated into WPC interfered with its physical and antimicrobial properties. ZO was found to be a viable radiopacifier that can be used with WPC.

  3. Urine pH test

    Science.gov (United States)

    ... urine test Male urinary tract References Bose A, Monk RD, Bushinsky DA. Kidney stones. In: Melmed S, Polonsky ... and its influence on urine pH. J Am Diet Assoc . 1995;95(7):791-797. PMID: 7797810 ...

  4. Exercise and Pulmonary Hypertension (PH)

    Science.gov (United States)

    ... Situations Find a Doctor PH Care Centers PHA Classroom PHA Registry Insurance Guide Specialty Pharmacy Other Resources ... no published data in the medical literature regarding routine exercise in patients with PAH. However, there are ...

  5. PhEDEx Data Service

    International Nuclear Information System (INIS)

    Egeland, Ricky; Wildish, Tony; Huang, Chih-Hao

    2010-01-01

    The PhEDEx Data Service provides access to information from the central PhEDEx database, as well as certificate-authenticated managerial operations such as requesting the transfer or deletion of data. The Data Service is integrated with the 'SiteDB' service for fine-grained access control, providing a safe and secure environment for operations. A plug-in architecture allows server-side modules to be developed rapidly and easily by anyone familiar with the schema, and can automatically return the data in a variety of formats for use by different client technologies. Using HTTP access via the Data Service instead of direct database connections makes it possible to build monitoring web-pages with complex drill-down operations, suitable for debugging or presentation from many aspects. This will form the basis of the new PhEDEx website in the near future, as well as providing access to PhEDEx information and certificate-authenticated services for other CMS dataflow and workflow management tools such as CRAB, WMCore, DBS and the dashboard. A PhEDEx command-line client tool provides one-stop access to all the functions of the PhEDEx Data Service interactively, for use in simple scripts that do not access the service directly. The client tool provides certificate-authenticated access to managerial functions, so all the functions of the PhEDEx Data Service are available to it. The tool can be expanded by plug-ins which can combine or extend the client-side manipulation of data from the Data Service, providing a powerful environment for manipulating data within PhEDEx.

  6. Economical wireless optical ratiometric pH sensor

    International Nuclear Information System (INIS)

    Vuppu, Sandeep; Kostov, Yordan; Rao, Govind

    2009-01-01

    The development and application of a portable, wireless fluorescence-based optical pH sensor is presented. The design incorporates the MSP430 microcontroller as the control unit, an RF transceiver for wireless communication, digital filters and amplifiers and a USB-based communication module for data transmission. The pH sensor is based on ratiometric fluorescence detection from pH sensitive dye incorporated in a peel-and-stick patch. The ability of the instrument to detect the pH of the solution with contact only between the sensor patch and the solution makes it partially non-invasive. The instrument also has the ability to transmit data wirelessly, enabling its use in processes that entail stringent temperature control and sterility. The use of the microcontroller makes it a reliable, low-cost and low-power device. The luminous intensity of the light source can be digitally controlled to maximize the sensitivity of the instrument. It has a resolution of 0.05 pH. The sensor is accurate and reversible over the pH range of 6.5–9

  7. Survey on the Labour Market Position of PhD Graduates: Competence comparison and relation between PhD and current employment

    Energy Technology Data Exchange (ETDEWEB)

    Heuritsch, J.; Waaijer, C.J.F.; Van der Weijden, I.C.M.

    2016-07-01

    We compared the skills PhD graduates acquired during their PhDs to the ones they need in their current job. We also studied the relation between PhD topic and content of the current job of recent PhD graduates. Data was collected in a survey of 1,133 respondents with a PhD from five Dutch universities between early 2008 and mid-2012. We show that scientific skills and independence are developed sufficiently during the PhD education, whereas PhDs are lacking in management and communication skills. These competence discrepancies were compared to the educational level required for the PhD holder’s current job and the relatedness of the current job to the PhD topic. (Author)

  8. Critical assessment of the pH of children's soap

    Directory of Open Access Journals (Sweden)

    Bruna Rafaela Mendes

    2016-06-01

    Full Text Available Abstract Objective: To evaluate the pH value of children's antibacterial soaps and syndets used in children's baths and verify whether there is information regarding pH on the product label. Methods: Quantitative, cross-sectional, analytical observational study that included ninety soap samples, both in bar and liquid presentations, as follows: 67 children's soap (group 1, 17 antibacterial soaps (group 2, and 6 syndets (group 3. Each sample had its pH measured after 1% dilution. In addition to descriptive statistics, the Pearson-Yates chi-squared test and Student's t-tests were applied, considering the minimal significance level of 5%. The Wilcoxon-Mann-Whitney test, Fisher's exact test, and the Kruskal-Wallis test were used for inferential statistics. Results: The pH levels varied considerably between liquid and bar presentations, with lower levels (4.4-7.9 found for the liquids (p < 0.05. Syndets showed pH levels close to the ideal (slightly acid and the antibacterial soaps showed the highest pH levels (up to 11.34 (p < 0.05. Only two of the soaps included in the study had information about their pH levels on the product packaging. Conclusions: Knowledge of the pH of children's soap by doctors and users is important, considering the great pH variability found in this study. Moreover, liquid soaps, and especially syndets, are the most recommended for the sensitive skin of neonates and infants, in order to guarantee skin barrier efficacy.

  9. Critical assessment of the pH of children's soap.

    Science.gov (United States)

    Mendes, Bruna Rafaela; Shimabukuro, Danielle Midori; Uber, Marjorie; Abagge, Kerstin Taniguchi

    2016-01-01

    To evaluate the pH value of children's antibacterial soaps and syndets used in children's baths and verify whether there is information regarding pH on the product label. Quantitative, cross-sectional, analytical observational study that included ninety soap samples, both in bar and liquid presentations, as follows: 67 children's soap (group 1), 17 antibacterial soaps (group 2), and 6 syndets (group 3). Each sample had its pH measured after 1% dilution. In addition to descriptive statistics, the Pearson-Yates chi-squared test and Student's t-tests were applied, considering the minimal significance level of 5%. The Wilcoxon-Mann-Whitney test, Fisher's exact test, and the Kruskal-Wallis test were used for inferential statistics. The pH levels varied considerably between liquid and bar presentations, with lower levels (4.4-7.9) found for the liquids (p<0.05). Syndets showed pH levels close to the ideal (slightly acid) and the antibacterial soaps showed the highest pH levels (up to 11.34) (p<0.05). Only two of the soaps included in the study had information about their pH levels on the product packaging. Knowledge of the pH of children's soap by doctors and users is important, considering the great pH variability found in this study. Moreover, liquid soaps, and especially syndets, are the most recommended for the sensitive skin of neonates and infants, in order to guarantee skin barrier efficacy. Copyright © 2016 Sociedade Brasileira de Pediatria. Published by Elsevier Editora Ltda. All rights reserved.

  10. A method for measuring pH at high temperatures is presented

    International Nuclear Information System (INIS)

    Chaudon, Luc.

    1979-01-01

    Two hydrogen electrodes are used and set up in a PTFE cell comprising two chambers connected through a saturated potassium chloride solution bridge. This cell is put in an autoclave containing hydrogen. The potential difference of the following cell is measured: H 2 , Pt, R solution - KCl saturated solution at 25 0 C - X solution, Pt, H 2 - The pH of the reference solution R is known up to 300 0 C and the X solution must have its pH to be determined. The precision of the measures at 300 0 C is estimated about +-0,1 pH unit. The dissociation constant of water is calculated from pH variations of alcaline solutions up to 300 0 C. The method has helped to measure the pH at 300 0 C of some boric acid solutions, with or without lithium hydroxide additions, in the following concentration range: B: 250 to 1500 ppm and Li: 0 to 3 ppm. Some concentrations are in fact those chosen for the primary circuits of pressurized water reactors. The pH of ammoniacal solutions is measured too and helped to determine the variations of the dissociation constant of ammonia with temperature [fr

  11. Modelling impacts of acid deposition and groundwater level on habitat quality and plant species diversity

    NARCIS (Netherlands)

    Kros, J.; Mol, J.P.; Wamelink, G.W.W.; Reinds, G.J.; Hinsberg, van A.; Vries, de W.

    2016-01-01

    Introduction
    We quantified the effects of the site factors pH and nitrate (NO3) concentration in soil solution and groundwater level on the vegetation of terrestrial ecosystems for the Netherlands in response to changes in atmospheric nitrogen (N) and sulphur (S) deposition and groundwater level

  12. The pH dependent Raman spectroscopic study of caffeine

    Science.gov (United States)

    Kang, Jian; Gu, Huaimin; Zhong, Liang; Hu, Yongjun; Liu, Fang

    2011-02-01

    First of all the surface enhanced Raman spectroscopy (SERS) and normal Raman spectra of caffeine aqueous solution were obtained at different pH values. In order to obtain the detailed vibrational assignments of the Raman spectroscopy, the geometry of caffeine molecule was optimized by density functional theory (DFT) calculation. By comparing the SERS of caffeine with its normal spectra at different pH values; it is concluded that pH value can dramatically affect the SERS of caffeine, but barely affect the normal Raman spectrum of caffeine aqueous solution. It can essentially affect the reorientation of caffeine molecule to the Ag colloid surface, but cannot impact the vibration of functional groups and chemical bonds in caffeine molecule.

  13. Solution chemistry of lanthanide complexes

    International Nuclear Information System (INIS)

    Brittain, H.G.

    1979-01-01

    Intermolecular energy transfer from Tb 3+ to Eu 3+ , luminescence intensity measurements, potentiometric titrations, differential absorption spectroscopy, and spectroscopic titrations were all used to study the binding of lanthanide ions by serine and threonine. At low pH (3.0 to 6.0) the complexes are mononuclear and ligand is only weakly bound. In the pH interval of 6.0 to 8.5 stronger interaction takes place between the ligand and the metal (with possible coordination of the undissociated hydroxyl group), and self-association of complexes becomes important. Above pH 8.5, base hydrolysis of the complexes leads to highly associated species in solution and shortly above this pH an insoluble precipitate is formed. It was found that energy could be transferred from Tb 3+ to Eu 3+ more efficiently among complexes prepared from racemic ligands than in complexes made from resolved ligand, but this stereoselectivity was only observed at pH values greater than 6.5 and in solutions having a 1:10 ratio of metal-to-ligand. No stereoselectivity was found in solutions having 1:5 ratios, and this observation was explained by the existence of 1:2 metal-ligand complexes existing in solutions having the higher ratio of metal-to-ligand (only 1:1 complexes are then found at lower ratios of metal-to-ligand). (author)

  14. Ratiometric Imaging of Extracellular pH in Dental Biofilms

    DEFF Research Database (Denmark)

    Schlafer, Sebastian; Dige, Irene

    2016-01-01

    The pH in bacterial biofilms on teeth is of central importance for dental caries, a disease with a high worldwide prevalence. Nutrients and metabolites are not distributed evenly in dental biofilms. A complex interplay of sorption to and reaction with organic matter in the biofilm reduces...... the diffusion paths of solutes and creates steep gradients of reactive molecules, including organic acids, across the biofilm. Quantitative fluorescent microscopic methods, such as fluorescence life time imaging or pH ratiometry, can be employed to visualize pH in different microenvironments of dental biofilms...... allows monitoring both vertical and horizontal pH gradients in real-time without mechanically disturbing the biofilm. However, care must be taken to differentiate accurately between extra- and intracellular compartments of the biofilm. Here, the ratiometric dye, seminaphthorhodafluor-4F 5-(and-6...

  15. Cadmium triggers Elodea canadensis to change the surrounding water pH and thereby Cd uptake.

    Science.gov (United States)

    Javed, M Tariq; Greger, Maria

    2011-01-01

    This study was aimed to investigate the influence of Elodea canadensis shoots on surrounding water pH in the presence of cadmium and the effect of plant-induced pH on cadmium uptake. The pH change in the surrounding nutrient solution and Cd uptake by Elodea shoots were investigated after cultivation of various plant densities (1, 3, 6 plants per 500 ml) in hydroponics at a starting pH of 4.0 and in the presence of different concentrations of cadmium (0, 0.1, 0.5 microM). Cadmium uptake was also investigated at different constant pH (4.0, 4.5, 5.5 and 6.5). To investigate if the pH change arose from photosynthetic activities, plants were grown under light, darkness or in the presence of a photosynthetic inhibitor, 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU), and 0.5 microM cadmium in the solution. Elodea had an ability to increase the surroundin