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1

Separation of Trivalent Actinides from Lanthanides in an Acetate Buffer Solution Using Cyanex 301  

SciTech Connect

The separation of trivalent actinides from the lanthanides using the active extractant in the Cyanex 301 reagent, bis(2,4,4-trimethylpentyl)dithiophosphinic acid, was studied. Specifically, the extractant was studied for an ammonium acetate/acetic acid buffered feed that would result from a transuranic separation process utilizing an ammonium acetate strip solution. Separation factors of 241Am from 154Eu with this extractant, as a function of total acetate concentration and pH, have been measured. Additionally, the extraction behavior of stable La, Ce, Pr, Nd, Sm, and Eu was measured. Separation factors were typically very high for Am from Eu at a pH ranging from 3.8 to 5.8 and a total acetate concentration ranging from 0.2 M to 1.0 M. However, separation factors across the lanthanide series varied considerably and resulted in separation of the lighter lanthanides from the heavier lanthanides at the higher pH’s.

Jack D. Law; Dean R. Peterman; Terry A. Todd; Richard D. Tillotson

2006-05-01

2

Second Dissociation Constant of Bis[(2-hydroxyethyl)amino]acetic Acid (BICINE) and pH of Its Buffer Solutions from 5 to 55 °C  

Microsoft Academic Search

The values of the second dissociation constant, K\\u000a 2, and related thermodynamic quantities of the ampholyte bis[(2-hydroxyethyl)amino]acetic acid (BICINE) have been determined at temperatures from 5 to 55 ?C. The pH values of six equimolal buffer solutions, and four buffer solutions having ionic strengths (I = 0.16 mol?kg?1) similar to those in blood plasma, have been evaluated at 12 temperatures

Lakshmi N. Roy; Rabindra N. Roy; Cole E. Denton; Sean R. LeNoue; Chandra N. Roy; Shahaf Ashkenazi; Thomas B. Williams; Daniel R. Church; Michael S. Fuge; Kartik N. Sreepada

2006-01-01

3

Buffer Index and Buffer Capacity for a Simple Buffer Solution  

NASA Astrophysics Data System (ADS)

Many papers that present the buffering effect of the simple buffer solution consider the notion of buffer index and buffer capacity as being equivalent. Moreover, IUPAC defies them as the same thing. According to the definition of the authors who have introduced these two units, the paper shows that there is a large difference between them. The buffer index can be defined as the differential ratio of the increase in the amount of strong acid or strong base added, to pH variation. The buffer capacity is numerically expressed to be equal with the minimum concentration of strong acid or strong base which causes the variation of buffer's pH with one unit. The field of application of both notions is different: the buffer capacity is used in the quantitative chemical analysis and the buffer index in studying biological systems.

Chiriac, Veronica; Balea, Gabriel

1997-08-01

4

Electrodialysis operation with buffer solution  

DOEpatents

A new method for improving the efficiency of electrodialysis (ED) cells and stacks, in particular those used in chemical synthesis. The process entails adding a buffer solution to the stack for subsequent depletion in the stack during electrolysis. The buffer solution is regenerated continuously after depletion. This buffer process serves to control the hydrogen ion or hydroxide ion concentration so as to protect the active sites of electrodialysis membranes. The process enables electrodialysis processing options for products that are sensitive to pH changes.

Hryn, John N. (Naperville, IL); Daniels, Edward J. (Orland Park, IL); Krumdick, Greg K. (Crete, IL)

2009-12-15

5

The effects of acetate buffer concentration on lysozyme solubility  

Microsoft Academic Search

The micro-solubility column technique was employed to systematically investigate the effects of buffer concentration on tetragonal lysozyme solubility. While keeping the NaCl concentrations constant at 2%, 3%, 4%, 5% and 7%, and the pH at 4.0, we have studied the solubility of tetragonal lysozyme over an acetate buffer concentration range of 0.01M to 0.5M as a function of temperature. The

Elizabeth L. Forsythe; Marc L. Pusey

1996-01-01

6

BAM R67: Salts-Phosphate Buffered Saline Solution (Salts ...  

Center for Food Safety and Applied Nutrition (CFSAN)

... BAM R67: Salts-Phosphate Buffered Saline Solution (Salts-PBS). January 2001. ... R67 Salts-Phosphate Buffered Saline Solution (Salts-PBS). ... More results from www.fda.gov/food/foodscienceresearch/laboratorymethods

7

Activity of NaOH buffered by silicate solids in molten sodium acetate-water at 317/sup 0/C  

SciTech Connect

Silica and sodium acetate are present in the steam generator tube sheet crevices of many nuclear power plants. Trace solutes in the condensate are tremendously concentrated in the crevices by boiling. Sparingly soluble sodium silicates and other solids precipitate from the crevice liquid leaving an extremely concentrated molten mixture of water, sodium acetate and other salts. The precipitates buffer the activity of sodium hydroxide in the superheated liquid that remains. The activity of NaOH corresponding to the buffers quartz/sodium disilicate and sodium disilicate/sodium metasilicate at 317/sup 0/C has been determined experimentally. The sodium hydroxide content of a sodium acetate-water melt buffered by these reactions was determined by chemical analysis, and the corresponding activity of NaOH at temperature was calculated using the recently published Pitzer-Simonson Model of molten salt-water mixtures. The molten mixture of sodium acetate and water plays the role solvent in these experiments and calculations. The free energies of formation of solid sodium silicates at 317/sup 0/C were also determined. The activity of NaOH corresponding to other silicate and phosphate buffers was calculated using published thermodynamic data and estimated from phase diagrams.

Weres, O.; Tsao, L.

1988-08-01

8

Effects of Acetate Buffer Concentration on Lysozyme Solubility.  

National Technical Information Service (NTIS)

The micro-solubility column technique was employed to systematically investigate the effects of buffer concentration on tetragonal lysozyme solubility. While keeping the NaCl concentrations constant at 2%, 3%, 4%, 5% and 7%, and the pH at 4.0, we have stu...

E. L. Forsythe M. L. Pusey

1996-01-01

9

Antimicrobial activity of borate-buffered solutions.  

PubMed Central

A minimal salts medium adjusted to physiological pH and osmolality was buffered with either 0.3% phosphate or 1.2% borate and evaluated for antimicrobial activity. The borate-buffered medium, either with or without a carbon source, exhibited significant antimicrobial activity against 15 Pseudomonas strains, 12 strains of enteric bacteria, and 7 strains of staphylococci. The borate-buffered system appears suitable for use as a generic vehicle for ophthalmic pharmaceutical agents.

Houlsby, R D; Ghajar, M; Chavez, G O

1986-01-01

10

RAD: A Compile-Time Solution to Buffer Overflow Attacks  

Microsoft Academic Search

Buffer overflow attack can inflict upon almost arbitrary programs and is one of the most common vulnerabilities that can seriously compromise the security of a network- attached computer system. This paper presents a compiler-based solution to the notorious buffer overflow attack problem. Using this solution, users can prevent attackers from compromising their systems by changing the return address to execute

Tzi-cker Chiueh; Fu-hau Hsu

2001-01-01

11

Alternative use of the SMP?buffer solution to determine lime requirement of soils  

Microsoft Academic Search

A close relationship was found between the pH of soil suspensions in the SMP buffer solution (pHsmp) and the potential acidity of soils (H + Al) extracted by a neutral calcium acetate solution (r = 0.98), for twenty six soil samples of the State of Sao Paulo, Brazil, This relationship was represented by the equation lnY = 7.76 ? 1.053X,

J. A. Quaggio; B. van Raij; E. Malavolta

1985-01-01

12

What's in Your Buffer? Solute Altered Millisecond Motions Detected by Solution NMR.  

PubMed

To date, little work has been conducted on the relationship between solute and buffer molecules and conformational exchange motion in enzymes. This study uses solution NMR to examine the effects of phosphate, sulfate, and acetate in comparison to MES- and HEPES-buffered references on the chemical shift perturbation and millisecond, chemical, or conformational exchange motions in the enzyme ribonuclease A (RNase A), triosephosphate isomerase (TIM) and HisF. The results indicate that addition of these solutes has a small effect on (1)H and (15)N chemical shifts for RNase A and TIM but a significant effect for HisF. For RNase A and TIM, Carr-Purcell-Meiboom-Gill relaxation dispersion experiments, however, show significant solute-dependent changes in conformational exchange motions. Some residues show loss of millisecond motions relative to the reference sample upon addition of solute, whereas others experience an enhancement. Comparison of exchange parameters obtained from fits of dispersion data indicates changes in either or both equilibrium populations and chemical shifts between conformations. Furthermore, the exchange kinetics are altered in many cases. The results demonstrate that common solute molecules can alter observed enzyme millisecond motions and play a more active role than what is routinely believed. PMID:23991940

Wong, Madeline; Khirich, Gennady; Loria, J Patrick

2013-08-30

13

Catalytic effect of buffers on the degradation of doripenem in aqueous solutions  

Microsoft Academic Search

The catalytic effect of buffers (phosphate, acetate, borate, carbonate) on the degradation of doripenem in aqueous solutions\\u000a was studied at 313 K in the pH range 0.82–11.56 (? = 0.50 mol L?1) by an HPLC-UV method developed for kinetic studies of doripenem. It was observed that general acid–base catalysis occurred\\u000a in all buffers and so catalytic rate constants were calculated. Specific acid–base catalysis of doripenem

Judyta Cielecka-Piontek; Anna Jeli?ska

2011-01-01

14

Influence of Medium Buffering Capacity on Inhibition of Saccharomyces cerevisiae Growth by Acetic and Lactic Acids  

PubMed Central

Acetic acid (167 mM) and lactic acid (548 mM) completely inhibited growth of Saccharomyces cerevisiae both in minimal medium and in media which contained supplements, such as yeast extract, corn steep powder, or a mixture of amino acids. However, the yeast grew when the pH of the medium containing acetic acid or lactic acid was adjusted to 4.5, even though the medium still contained the undissociated form of either acid at a concentration of 102 mM. The results indicated that the buffer pair formed when the pH was adjusted to 4.5 stabilized the pH of the medium by sequestering protons and by lessening the negative impact of the pH drop on yeast growth, and it also decreased the difference between the extracellular and intracellular pH values (?pH), the driving force for the intracellular accumulation of acid. Increasing the undissociated acetic acid concentration at pH 4.5 to 163 mM by raising the concentration of the total acid to 267 mM did not increase inhibition. It is suggested that this may be the direct result of decreased acidification of the cytosol because of the intracellular buffering by the buffer pair formed from the acid already accumulated. At a concentration of 102 mM undissociated acetic acid, the yeast grew to higher cell density at pH 3.0 than at pH 4.5, suggesting that it is the total concentration of acetic acid (104 mM at pH 3.0 and 167 mM at pH 4.5) that determines the extent of growth inhibition, not the concentration of undissociated acid alone.

Thomas, K. C.; Hynes, S. H.; Ingledew, W. M.

2002-01-01

15

A nitrilo-tri-acetic-acid/acetic acid route for the deposition of epitaxial cerium oxide films as high temperature superconductor buffer layers  

SciTech Connect

A water based cerium oxide precursor solution using nitrilo-tri-acetic-acid (NTA) and acetic acid as complexing agents is described in detail. This precursor solution is used for the deposition of epitaxial CeO{sub 2} layers on Ni-5at%W substrates by dip-coating. The influence of the complexation behavior on the formation of transparent, homogeneous solutions and gels has been studied. It is found that ethylenediamine plays an important role in the gelification. The growth conditions for cerium oxide films were Ar-5% gas processing atmosphere, a solution concentration level of 0.25 M, a dwell time of 60 min at 900 {sup o}C and 5-30 min at 1050 {sup o}C. X-ray diffraction (XRD), scanning electron microscope (SEM), atomic force microscopy (AFM), pole figures and spectroscopic ellipsometry were used to characterize the CeO{sub 2} films with different thicknesses. Attenuated total reflection-Fourier transform infrared (ATR-FTIR) was used to determine the carbon residue level in the surface of the cerium oxide film, which was found to be lower than 0.01%. Textured films with a thickness of 50 nm were obtained. - Graphical abstract: Study of the complexation and hydrolysis behavior of Ce{sup 4+} ions in the presence of nitrilo-tri-acetic acid and the subsequent development of an aqueous chemical solution deposition route suited for the processing of textured CeO{sub 2} buffer layers on Ni-W tapes.

Thuy, T.T.; Lommens, P.; Narayanan, V.; Van de Velde, N.; De Buysser, K.; Herman, G.G.; Cloet, V. [Department of Inorganic and Physical Chemistry, Ghent University, Krijgslaan 281 - S3, 9000 Gent (Belgium); Van Driessche, I., E-mail: Isabel.Vandriessche@UGent.b [Department of Inorganic and Physical Chemistry, Ghent University, Krijgslaan 281 - S3, 9000 Gent (Belgium)

2010-09-15

16

Application of acetate buffer in pH adjustment of sorghum mash and its influence on fuel ethanol fermentation.  

PubMed

A 2 M sodium acetate buffer at pH 4.2 was tried to simplify the step of pH adjustment in a laboratory dry-grind procedure. Ethanol yields or conversion efficiencies of 18 sorghum hybrids improved significantly with 2.0-5.9% (3.9% on average) of relative increases when the method of pH adjustment changed from traditional HCl to the acetate buffer. Ethanol yields obtained using the two methods were highly correlated (R (2) = 0.96, P < 0.0001), indicating that the acetate buffer did not influence resolution of the procedure to differentiate sorghum hybrids varying in fermentation quality. Acetate retarded the growth of Saccharomyces cerevisiae, but did not affect the overall fermentation rate. With 41-47 mM of undissociated acetic acid in mash of a sorghum hybrid at pH 4.7, rates of glucose consumption and ethanol production were inhibited during exponential phase but promoted during stationary phase. The maximum growth rate constants (mu(max)) were 0.42 and 0.32 h(-1) for cells grown in mashes with pH adjusted by HCl and the acetate buffer, respectively. Viable cell counts of yeast in mashes with pH adjusted by the acetate buffer were 36% lower than those in mashes adjusted by HCl during stationary phase. Coupled to a 5.3% relative increase in ethanol, a 43.6% relative decrease in glycerol was observed, when the acetate buffer was substituted for HCl. Acetate helped to transfer glucose to ethanol more efficiently. The strain tested did not use acetic acid as carbon source. It was suggested that decreased levels of ATP under acetate stress stimulate glycolysis to ethanol formation, increasing its yield at the expense of biomass and glycerol production. PMID:18839230

Zhao, Renyong; Bean, Scott R; Crozier-Dodson, Beth Ann; Fung, Daniel Y C; Wang, Donghai

2008-10-07

17

Seed layer, solution concentration and thickness effects on CSD-derived La 2Zr 2O 7 buffer layers for coated conductors  

Microsoft Academic Search

La2Zr2O7\\/NiW buffer layers as very promising buffer layers for coated conductors were fabricated by chemical solution deposition using cheap precursors, La-acetate and Zr-(IV) n-propoxide (70% w\\/w in n-propanol). The effects on the orientation and microstructure of La2Zr2O7 buffer layers, including seed layer, thickness and solution concentration, were investigated. The results showed that insertion of a seed layer could obviously improve

X. B. Zhu; H. C. Lei; D. Q. Shi; L. Zhang; L. Wang; Y. P. Sun; W. H. Song; Z. R. Yang; J. H. Kim; R. Zeng; S. X. Dou; J. Yang; H. W. Gu

2007-01-01

18

Use of buffered hypochlorite solution for disinfecting fibrescopes.  

PubMed Central

The possible use of sodium hypochlorite solution buffered to pH 7.6 and containing 100 ppm available chlorine (avCl) for disinfecting fibrescopes was investigated. A flexible fibrescope experimentally contaminated with Pseudomonas putida, Mycobacterium fortuitum, or Bacillus subtilis spores was effectively disinfected within 10 m in repeatedly and without any observable adverse effect on the instrument. The corrosive nature of buffered hypochlorite was investigated by immersing various fibrescope components and metal wires in solutions of different strength for long periods and examining them for damage. Stainless steel, platinum, glass, Teflon, polythene and epoxy resin were apparently unaffected whereas polyurethane, rubber and other metals tested were damaged to different extents. Buffered hypochlorite solutions may have many applications pertaining to the disinfection of items which are either thermolabile or require rapid effective disinfection.

Coates, D; Death, J E

1982-01-01

19

Separation of inorganic anions and cations on titania by use of acetic acid-sodium acetate and bicine-sodium hydroxide buffers  

Microsoft Academic Search

Summary  The ion-exchange retention behavior of titania synthesized in our laboratory was investigated by ion chromatography of inorganic\\u000a anions and cations. Dilute acetic acid-sodium acetate and bicine-sodium hydroxide buffers were used as mobile phases with\\u000a no use of suppresor. We observed that the titania, although poor at separating monovalent anions expcept nitrite ion in this\\u000a experiment, was both an anion and

K. Tani; H. Kubojima

1998-01-01

20

Application of acetate buffer in pH adjustment of sorghum mash and its influence on fuel ethanol fermentation  

Microsoft Academic Search

A 2 M sodium acetate buffer at pH 4.2 was tried to simplify the step of pH adjustment in a laboratory dry-grind procedure.\\u000a Ethanol yields or conversion efficiencies of 18 sorghum hybrids improved significantly with 2.0–5.9% (3.9% on average) of\\u000a relative increases when the method of pH adjustment changed from traditional HCl to the acetate buffer. Ethanol yields obtained\\u000a using the

Renyong Zhao; Scott R. Bean; Beth Ann Crozier-Dodson; Daniel Y. C. Fung; Donghai Wang

2009-01-01

21

Application of Acetate Buffer in pH Adjustment of Mash and its Influence on Fuel Ethanol Fermentation  

Technology Transfer Automated Retrieval System (TEKTRAN)

A 2M sodium acetate buffer at pH 4.2 was used to adjust pH of liquefied mashes in a simultaneous saccharification and fermentation (SSF) procedure. Although 5 mL of the buffer did not bring the pH values of the mashes (~100 mL) from a sorghum hybrid to 4.2, it kept the system stable (pH from 4.7 to ...

22

Radical-Chain Reactions of Acetals in Solution  

NASA Astrophysics Data System (ADS)

Experimental results on the liquid-phase radical-chain reactions of acetals are summarised. Factors influencing the rate of formation, structure, and properties of free radicals generated from cyclic and linear acetals are discussed. Attention is paid mainly to the kinetics and the mechanism of the reactions of mono- and di-alkoxyalkyl radicals in solution. The relation between the structure of acetals and their reactivity towards various radicals is examined. Data are given illustrating the possibility of using homolytic liquid-phase reactions of acetals in organic synthesis. A list of 77 references is included.

Rakhmankulov, D. L.; Zlotskii, S. S.; Zorin, V. V.; Imashev, U. B.; Karakhanov, Robert A.

1981-08-01

23

Advanced titania buffer layer architectures prepared by chemical solution deposition  

NASA Astrophysics Data System (ADS)

Chemical solution deposition (CSD) was used to grow high-quality (100) oriented films of SrTiO3 (STO) on CSD CaTiO3 (CTO), Ba0.1Ca0.9TiO3 (BCT) and STO seed and template layers. These template films bridge the lattice misfit between STO and the nickel-tungsten (NiW) substrate, assisting in dense growth of textured STO. Additional niobium (Nb) doping of the STO buffer layer reduces oxygen diffusion which is necessary to avoid undesired oxidation of the NiW. The investigated templates offer suitable alternatives to established standard buffer systems like La2Zr2O7 (LZO) and CeO2 for coated conductors.

Kunert, J.; Bäcker, M.; Brunkahl, O.; Wesolowski, D.; Edney, C.; Clem, P.; Thomas, N.; Liersch, A.

2011-08-01

24

Automatic initialisation of buffer composition estimation for on-line analysis of unknown buffer solutions.  

PubMed

An automatic initialisation procedure for extracting useful information about buffer composition from a titration experiment is presented in this paper. The initialisation procedure identifies which buffering components are present in the sample from a relatively long list of buffers expected in the system monitored. The procedure determines approximate pKa values of the buffers and evaluates their maximum and minimum concentrations. This information is then used to start an optimisation procedure to fit the model of the buffer components to the titration data and to accurately determine buffer concentrations and pKa values. The procedure has been integrated as a software layer around the buffer capacity optimum model builder (BOMB) that fits a buffer-capacity model to a measured buffer-capacity curve to estimate model properties (pKa values and concentrations). The reliability and robustness of the resulting buffer capacity software (BCS) were tested using a titrimetric analyser simulator (TAS). The BCS was then validated off-line and on-line. PMID:16184364

Zaher, Usama E; Vanrolleghem, Peter A

2005-10-19

25

Evaluation of the acetate buffer attack of a sequential extraction scheme for marine particulate metal speciation studies by scanning electron microscopy with energy dispersive X-ray analysis  

Microsoft Academic Search

Scanning electron microscopy, with energy dispersive X-ray analysis (SEM-EDX), has been used to evaluate and possibly optimize, the first step (acetate buffer attack for exchangeable and carbonatic fractions) of a sequential selective extraction scheme. The extraction has been performed on two different particulates, a certified reference plankton and a real marine suspended particulate, using an increased acetate concentration and various

F Baffi; C Ianni; M Ravera; F Soggia; E Magi

1998-01-01

26

Effect of buffered solutions and sulfate on vegetative and sexual development in gametophytes of Pteridium aquilinum  

Microsoft Academic Search

Experiments were performed to determine effects of buffered solutions (0.01 M) on vegetative development and fertilization of gametophytes of Pteridium aquilinum. Buffered solutions were used to simulate exposures to acidic precipitation up to 3.5 h. Flagellar movement of sperm was reduced at buffer pH levels below 5.8. Specifically, longevity of motility was reduced so that no movements were observed 8

Lance S. Evans; Donna M. Bozzone

1977-01-01

27

Superconducting films made by spin-coating of acetate solutions  

SciTech Connect

Metallic silver substrates were spin-coated with several layers of mixed acetate solutions containing bismuth, lead, strontium, calcium, and copper. The viscosities of the cation solutions were modified by the addition of polyvinyl alcohol. The films were heat treated at various temperatures in air, O{sub 2}, and 1% O{sub 2} (balance N{sub 2}) atmospheres. Bismuth cuprate films with transport critical current densities {approx}500 A/cm{sup 2} were obtained in this work. New conditions of coating and sintering have been tried to produce superconducting films.

Balachandran, U.; Poeppel, R.B. (Argonne National Lab., IL (USA)); dos Santos, D.I.; Carvalho, C.L.; da Silva, R.R.; Aegerter, M.A. (Sao Paulo Univ., Sao Carlos, SP (Brazil). Inst. de Fisica e Quimica)

1990-12-01

28

Seed layer, solution concentration and thickness effects on CSD-derived La2Zr2O7 buffer layers for coated conductors  

NASA Astrophysics Data System (ADS)

La2Zr2O7/NiW buffer layers as very promising buffer layers for coated conductors were fabricated by chemical solution deposition using cheap precursors, La-acetate and Zr-(IV) n-propoxide (70% w/w in n-propanol). The effects on the orientation and microstructure of La2Zr2O7 buffer layers, including seed layer, thickness and solution concentration, were investigated. The results showed that insertion of a seed layer could obviously improve the crystallization and orientation, and decrease of single layer thickness could also obviously improve the in-plane orientation. The results of all metalorganic depositions derived YBCO/CeO2/La2Zr2O7/NiW showed that the prepared La2Zr2O7 buffer layers were suitable for coated conductors using all metalorganic depositions.

Zhu, X. B.; Lei, H. C.; Shi, D. Q.; Zhang, L.; Wang, L.; Sun, Y. P.; Song, W. H.; Yang, Z. R.; Kim, J. H.; Zeng, R.; Dou, S. X.; Yang, J.; Gu, H. W.

2007-12-01

29

Corrosion behavior of mild steel in acetic acid solutions  

SciTech Connect

The corrosion behavior of mild steel in acetic acid (CH{sub 3}COOH) solutions was studied by weight loss and potentiostatic polarization techniques. The variation in corrosion rate of mild steel with concentrations of CH{sub 3}COOH, evaluated by weight loss and electrochemical techniques, showed marked resemblance. From both techniques, the maximum corrosion rate was observed for 20% CH{sub 3}COOH solution at all three experimental temperatures (25, 35, and 45 C). Anodic polarization curves showed active-passive behavior at each concentration, except at 80% CH{sub 3}COOH. Critical current density (i{sub c}) passive current density (I{sub n}), primary passivation potential (E{sub pp}), and potential for passivity (E{sub p}) had their highest values in 20% CH{sub 3}COOH solution. With an increase in temperature, while the anodic polarization curves shifted toward higher current density region at each concentration, the passive region became progressively less distinguishable. With the addition of sodium acetate (NaCOOCH{sub 3}) as a supporting electrolyte, the passive range was enlarged substantially. However, the transpassive region commenced at more or less the same potential. Cathodic polarization curves were almost identical irrespective of the concentration of CH{sub 3}COOH or temperature.

Singh, M.M.; Gupta, A.

2000-04-01

30

The Determination of the pH of Standard Buffer Solution: A Laboratory Experiment.  

ERIC Educational Resources Information Center

|Describes an experiment which shows: (1) how measurements of the reaction electromotive force for the cell (Pt/glass/NaCl(aq,m),buffer/AgCl/Ag/Pt) can be utilized in determining the absolute pH of the buffer; and (2) the demonstration of the use of the Debye-Huckel model of an electrolyte solution in solving an important electrochemical problem.…

Harris, K. R.

1985-01-01

31

Acid–base buffering in organ preservation solutions as a function of temperature: new parameters for comparing buffer capacity and efficiency  

Microsoft Academic Search

Control of acidity and preventing intracellular acidosis are recognized as critical properties of an effective organ preservation solution. Buffer capacity and efficiency are therefore important for comparing the relative merits of preservation fluids for optimum hypothermic storage, but these parameters are not available for the variety of organ preservation solutions of interest in transplantation today. Moreover, buffer capacity is dependent

Simona C Baicu; Michael J Taylor

2002-01-01

32

Low-temperature solution-processed metal oxide buffer layers fulfilling large area production requirements  

NASA Astrophysics Data System (ADS)

This paper is a review of our previous work on the field of low temperature, solution processed metal oxide buffer layers published in various journals. Our work focuses on zinc oxide (ZnO) and aluminum-doped zinc oxide (AZO) as n-type and molybdenum oxide (MoO3) as p-type solution processed buffer layer. In addition to that, we investigate the surface modification of AZO using phosphonic acid-anchored aliphatic and fullerene self assembled monolayers (SAMs).

Stubhan, T.; Litzov, I.; Li, Ning; Wang, H. Q.; Krantz, J.; Machui, F.; Steidl, M.; Oh, H.; Matt, G. J.; Brabec, C. J.

2012-09-01

33

In situ XANES study of the passive film formed on iron in borate buffer and in sodium acetate  

SciTech Connect

The passive film formed on Fe in pH 8.4 borate buffer (0. 1 36 M) over a broad potential range was characterized by in situ XANES (x-ray absorption near edge structure). On stepping the potential to a value between -0.6 V and +0.4 V (MSE), a passive film forms without detectable dissolution. The edge position indicates that the valence state of Fe in the film is 10 {+-} 5% Fe{sup 2+} and 90 {+-} 5% Fe{sup 3+}. Formation of a passive film at potentials between -0.8 V and -0.65 V is associated with dissolution prior to passivation, and a lower average valence state of 17 {+-} 5% Fe{sup 2+} and 83 {+-} 5% Fe{sup 3+}. At -0.9 V, the Fe did not passivate. The passive film that forms in pH 8.2 sodium acetate (0.1 M) at +0.4 V gives an edge similar to the high potential passive film formed in borate buffer, but dissolution occurs prior to passivation.

Oblonsky, L.J.; Ryan, M.P.; Isaacs, S. [and others

1996-12-31

34

Electrochemical behavior of superconducting Bi{sub 1.4}Pb{sub 0.6}Sr{sub 2}Ca{sub 2}Cu{sub 3}O{sub 10} in halide-containing acetate buffer  

SciTech Connect

Electrochemical responses of Bi{sub 1.4}Pb{sub 0.6}Sr{sub 2}Ca{sub 2}Cu{sub 3}O{sub 10} in various buffered halide solutions were studied. Electrochemical surface alterations in the anodic and cathodic potentials were investigated by x-ray diffraction of the surfaces after potentiostatic exposures in the different media. The principal electrochemical reactions involved in alteration of the surface of the superconductor were identified by considering its potentiodynamic response as well as the post-exposure surface constitution. Formation and stability of bismuth and bismuth trioxide were found to be significant in deciding the surface composition after electrochemical exposure in acetate buffer and buffers containing chloride and fluoride. The electrochemical process was controlled by chemical reaction and diffusion in the presence of iodide.

Chattoraj, I.; Pathak, L.C. [National Metallurgical Lab., Jamshedpur (India)

1998-06-01

35

Tissue-dissolving capacity and antibacterial effect of buffered and unbuffered hypochlorite solutions  

Microsoft Academic Search

Objective. The goal of this study was to compare the dissolving potential of Dakin's solution with that of equivalent buffered and unbuffered sodium hypochlorite solutions on fresh and decayed tissues. In addition, the antimicrobial effect of Dakin's solution and equivalent unbuffered hypochlorite was tested. Study Design. Tissue specimens were obtained from freshly dissected pig palates. Unbuffered 2.5% and 0.5% sodium

Matthias Zehnder; Daniel Kosicki; Hansueli Luder; Beatrice Sener; Tuomas Waltimo

2002-01-01

36

Tissue-dissolving capacity and antibacterial effect of buffered and unbuffered hypochlorite solutions  

Microsoft Academic Search

Objective. The goal of this study was to compare the dissolving potential of Dakin's solution with that of equivalent buffered and unbuffered sodium hypochlorite solutions on fresh and decayed tissues. In addition, the antimicrobial effect of Dakin's solution and equivalent unbuffered hypochlorite was tested. Study design. Tissue specimens were obtained from freshly dissected pig palates. Unbuffered 2.5% and 0.5% sodium

Matthias Zehnder; Daniel Kosicki; Hansueli Luder; Tuomas Waltimo

2002-01-01

37

Preparation of Buffer Layers on Textured Ni5W Substrates by Chemical Solution Deposition Method  

Microsoft Academic Search

CeO2 caped La2Zr2O7 (LZO) buffer layers on cube-textured Ni5W substrates were fabricated by the method of chemical solution deposition(CSD). The orientation of both LZO film and CeO2\\/LZO buffer layer was investigated using conventional XRD and X-ray four circle diffractometers, respectively. The results reveal that both the LZO film on Ni5W substrates and CeO2 film on LZO buffer layer are grown

Yanling Cheng; Hongli Suo; Dong He; Yue Zhao; Mangmang Gao; Min Liu; Ye Shuai; Yonghua Zhu; Rong Wang; Lin Ma; Meiling Zhou

2009-01-01

38

A Simple and Universal Method for Making up Buffer Solutions.  

ERIC Educational Resources Information Center

|Uses a method which involves weighing out an amount of the appropriate weak acid or base and dissolving it in distilled water close to the final volume. Solution is then titrated with strong acid or base to give the desired pH. Provides three examples. (MVL)|

Dennison, Clive

1988-01-01

39

A pitzer mixed electrolyte solution theory approach to assignment of pH to standard buffer solutions  

Microsoft Academic Search

The IUPAC recommendations for the pH scale for aqueous solutions are based on the Bates-Guggenheim (B-G) convention (1961) for the single ion activity coefficient of the chloride ion in the standard buffer(s). This convention was adopted as a reasonable estimate based on the Debye-Huckel theory and is limited in its application to ionic strengths less than 0.1 mol-kg-1. This approach

A. K. Covington; M. I. A. Ferra

1994-01-01

40

Dependence of the mobility of molecular probes in cellulose acetate solutions on complexation and the solution structure  

Microsoft Academic Search

The spin echo technique with a magnetic field pulse gradient was used to measure the translational diffusion coefficients D of molecular probes in solutions of cellulose acetates in dimethyl sulfoxide. A linear dependence of coefficient D on the extent of substitution of the cellulose acetate was established and the sensitivity of D to the supermolecular structure of the polymer solution

O. D. Vetrov; A. M. Gladkii; V. A. Daragan; E. É. Il'ina; D. A. Moskalev; V. V. Myasoedova; A. É. Prizment

1990-01-01

41

Thick lanthanum zirconate buffer layers from water-based precursor solutions on Ni-5%W substrates  

SciTech Connect

In this work, water-based precursor solutions suitable for dip-coating of thick La{sub 2}Zr{sub 2}O{sub 7} (LZO) buffer layers for coated conductors on Ni-5%W substrates were developed. The solutions were prepared based on chelate chemistry using water as the main solvent. The effect of polymer addition on the maximum crack-free thickness of the deposited films was investigated. This novel solution preparation method revealed the possibility to grow single, crack-free layers with thicknesses ranging 100-280 nm with good crystallinity and an in-plane grain misalignment with average FWHM of 6.55{sup o}. TEM studies illustrated the presence of nanovoids, typical for CSD-LZO films annealed under Ar-5%H{sub 2} gas flow. The appropriate buffer layer action of the film in preventing the Ni diffusion was studied using XPS. It was found that the Ni diffusion was restricted to the first 30 nm of a 140 nm thick film. The surface texture of the film was improved using a seed layer. - Graphical abstract: Thick LZO buffer layers from water-based precursor solutions were synthesized and their crystallinity, microstructure and buffer layer action were studied. The buffer layer action of the LZO layer was substantial to restrict the Ni penetration within 30 nm of a 140 nm thick film. Highlights: > LZO buffer layers with high thicknesses for use in coated conductors were prepared. > Prepared from water-based solutions. > Polymeric PVP increases the crack-free critical thickness of thick films. > Thick films showed good barrier action against Ni penetration. > Seed layers promote epitaxial growth of thick layers.

Narayanan, Vyshnavi; Lommens, Petra; De Buysser, Klaartje [SCRIPTS, Department of Inorganic and Physical Chemistry, Ghent University, Krijgslaan 281-S3, B-9000 Gent (Belgium); Huehne, Ruben [IFW Dresden, Institute for Metallic Materials, Helmholtzstrasse 20, 01069 Dresden (Germany); Van Driessche, Isabel, E-mail: Isabel.Vandriessche@UGent.Be [SCRIPTS, Department of Inorganic and Physical Chemistry, Ghent University, Krijgslaan 281-S3, B-9000 Gent (Belgium)

2011-11-15

42

Influence of an acetate- and a lactate-based balanced infusion solution on acid base physiology and hemodynamics: an observational pilot study  

PubMed Central

Background The current pilot study compares the impact of an intravenous infusion of Ringer’s lactate to an acetate-based solution with regard to acid–base balance. The study design included the variables of the Stewart approach and focused on the effective strong ion difference. Because adverse hemodynamic effects have been reported when using acetate buffered solutions in hemodialysis, hemodynamics were also evaluated. Methods Twenty-four women who had undergone abdominal gynecologic surgery and who had received either Ringer’s lactate (Strong Ion Difference 28 mmol/L; n?=?12) or an acetate-based solution (Strong Ion Difference 36.8 mmol/L; n?=?12) according to an established clinical protocol and its precursor were included in the investigation. After induction of general anesthesia, a set of acid–base variables, hemodynamic values and serum electrolytes was measured three times during the next 120 minutes. Results Patients received a mean dose of 4,054?±?450 ml of either one or the other of the solutions. In terms of mean arterial blood pressure and norepinephrine requirements there were no differences to observe between the study groups. pH and serum HCO3- concentration decreased slightly but significantly only with Ringer’s lactate. In addition, the acetate-based solution kept the plasma effective strong ion difference more stable than Ringer’s lactate. Conclusions Both of the solutions provided hemodynamic stability. Concerning consistency of acid base parameters none of the solutions seemed to be inferior, either. Whether the slight advantages observed for the acetate-buffered solution in terms of stability of pH and plasma HCO3- are clinically relevant, needs to be investigated in a larger randomized controlled trial.

2012-01-01

43

Enzymatic degradation of poly(?-caprolactone)\\/poly( dl-lactide) blends in phosphate buffer solution  

Microsoft Academic Search

Blend films of poly(?-caprolactone) (PCL) and poly(dl-lactide) (PDLLA) with 0.5 weight fraction of PCL were prepared by means of solution casting and their degradation behavior was studied in phosphate buffer solution containing Pseudomonas (PS) lipase. Enzymatic degradation of the blend films occurred continuously within the first 6days and finally stopped when the film weight loss reached 50%, showing that only

Zhihua Gan; Donghong Yu; Zhiyuan Zhong; Qizhi Liang; Xiabin Jing

1999-01-01

44

Evaluation of kinetic parameters of uranyl acetate complexes in ethanolic solution by cyclic voltammetry  

Microsoft Academic Search

The complexation of uranyl ion with acetate ions was investigated in 20% ethanolic solution by using cyclic voltammetry. The\\u000a uranium formed 1:1 and 1:2 complexes with acetate ions. The values of log ?1 and log ?2 for uranyl acetate complexes were 2.05 ± 0.08 and 5.25 ± 0.06 respectively. The diffusion coefficient and heterogeneous rate\\u000a constants for the reduction of uranyl ion at hanging

A. S. A. Khan; R. Ahmed; M. L. Mirza

2010-01-01

45

Intramolecular carbon isotopic analysis of acetic acid by direct injection of aqueous solution  

Microsoft Academic Search

We report an improved method for determining the intramolecular carbon isotopic composition of acetate using direct injection of aqueous samples. The system builds upon prior work that established pyrolytic conditions for online analysis and represents a significant advance in that it requires minimal preparation for samples containing as little as 1mM sodium acetate in aqueous solution. The technique is applicable

Burt Thomas; Katherine H. Freeman; Michael A. Arthur

2009-01-01

46

Solution-Processed MoSx as an Efficient Anode Buffer Layer in Organic Solar Cells.  

PubMed

We reported a facile solution-processed method to fabricate a MoSx anode buffer layer through thermal decomposition of (NH4)2MoS4. Organic solar cells (OSCs) based on in situ growth MoSx as the anode buffer layer showed impressive improvements, and the power conversion efficiency was higher than that of conventional PEDOT:PSS-based device. The MoSx films obtained at different temperatures and the corresponding device performance were systematically studied. The results indicated that both MoS3 and MoS2 were beneficial to the device performance. MoS3 could result in higher Voc, while MoS2 could lead to higher Jsc. Our results proved that, apart from MoO3, molybdenum sulfides and Mo(4+) were also promising candidates for the anode buffer materials in OSCs. PMID:24018132

Li, Xiaodong; Zhang, Wenjun; Wu, Yulei; Min, Chao; Fang, Junfeng

2013-09-12

47

On the Structure of Cellulose Acetate Molecules in Acetone Solution  

Microsoft Academic Search

Data obtained from sedimentation velocity and viscosity measurements on a series of cellulose acetate fractions in acetone are interpreted in terms of two models, the impenetrable ellipsoid of rotation and the uniform density random coil. The lack of agreement using the former model is shown to be a real effect, rather than one determined by experimental inaccuracy. As other investigations

Seymour J. Singer; Herman Mark

1948-01-01

48

Influence of pH, temperature and buffers on cefepime degradation kinetics and stability predictions in aqueous solutions.  

PubMed

First-order rate constants (k) were determined for cefepime degradation at 45, 55, 65, and 75 degrees C, pH 0.5 to 8.6, using an HPLC assay. Each pH-rate profile exhibited an inflection between pH 1 and 2. The pH-rate expression was k(pH) = kH1 f1(aH+) + kH2 f2(aH+) + ks + kOH(aOH-), where kH1 and kH2 are the catalytic constants (M(-1) h(-1)) for hydrogen ion activity (aH+), kOH is the catalytic constant for hydroxyl ion activity (aOH-), and ks is the first-order rate constant (h(-1)) for spontaneous degradation. The protonated (f1) and unprotonated (f2) fractions were calculated from the dissociation constant, Ka = (8.32x10(-6))e(5295)/RT where T was absolute temperature (T). Accelerated loss due to formate, acetate, phosphate, and borate buffer catalysis was quantitatively described with the catalytic constant, kGA (M(-1) h(-1)) for the acidic component, [GA], and kGB (M(-1) h(-1) for the basic component, [GB], of each buffer. The temperature dependency for each rate constant was defined with experimentally determined values for A and E and the Arrhenius expression, kT = Ae-E/RT, where kT represented kH1, kH2 , kS, kOH, kGA, or kGB. Degradation rate constants were calculated for all experimental pH, temperature, and buffer conditions by combining the contributions from pH and buffer effects to yield, k = k(pH) + kGA[GA] + kGB[GB]. The calculated k values had <10% error for 103 of the 106 experimentally determined values. Maximum stability was observed in the pH-independent region, 4 to 6. Degradation rate constants were predicted and experimentally verified for cefepime solutions stored at 30 degrees C, pH 4.6 and 5.6. These solutions maintained 90% of their initial concentration (T90) for approximately 2 days. PMID:10189269

Fubara, J O; Notari, R E

1998-12-01

49

The potentiometric determination of stability constants for zinc acetate complexes in aqueous solutions to 295C  

SciTech Connect

A potentiometric method was used to determine the formation quotients of zinc acetate complexes in aqueous solutions from 50 to 295C at ionic strengths of 0.03, 0.3, and 1.0 m. The potentiometric titrations were carried out in an externally heated, Teflon-lined concentration cell fitted with hydrogen electrodes. Formal sodium acetate concentrations of the experimental solutions ranged from 0.001 to 0.1 m with acetic acid to sodium acetate ratios ranging from 30 to 300. Sodium trifluoromethanesulfonate (F{sub 3}CSO{sub 3}Na) was used as a supporting electrolyte. Stoichiometries and formation quotients for the complexes ZnCH{sub 3}COO{sup +}, Zn(CH{sub 3}COO){sub 2}, and Zn(CH{sub 3}COO){sub 3}{sup {minus}} were derived from the titration data by regression analysis. Stability constants at infinite dilution (K{sub n}) and other relevant thermodynamic quantities were calculated for these three complexes. Calculations of zinc speciation in acetate-chloride solutions show that zinc acetate complexes should have an importance similar to zinc chloride complexes in high acetate waters where chloride to acetate molal ratios are less than about 10.

Giordano, T.H. (New Mexico State Univ., Las Cruces (United States)); Drummond, S.E. (Oak Ridge National Lab., TN (United States))

1991-09-01

50

Liquid crystalline solutions of cellulose acetate in phosphoric acid  

Microsoft Academic Search

The influence has been studied of both the acid strength of phosphoric acid and the degree of substitution of cellulose acetate on the formation of an anisotropic phase. The solvent composition is expressed as a P2O5 concentration. It was found that the clearing temperature increases strongly with decreasing amount of water in the solvent.The influence of the degree of substitution

H Boerstoel; H Maatman; S. J Picken; R Remmers; J. B Westerink

2001-01-01

51

Investigation of Intermolecular Association in Concentrated Solutions of Cellulose Acetate.  

National Technical Information Service (NTIS)

The role of intermolecular association in concentrated solutions of cellulose triacetate (CTA) is investigated with respect to its importance in controlling the properties of CTA films formed from concentrated solutions for use, for example, as membranes ...

G. C. Berry T. S. Sham M. A. Leech

1979-01-01

52

La2Zr2O7 and Ce Gd O buffer layers for YBCO coated conductors using chemical solution deposition  

NASA Astrophysics Data System (ADS)

Biaxially textured La2Zr2O7 (LZO) and Ce Gd O (CGO) buffer layers were grown on Ni-RABiTS (rolling-assisted biaxially textured substrates) to obtain suitable buffer layer architectures for YBa2Cu3O7-x (YBCO) coated conductors. Both buffer systems were prepared using newly developed precursor solutions containing a simple carboxylic acid as solvent. Reproducible highly textured LZO buffer layers were obtained at annealing temperatures as low as 900 °C. CGO buffer layers were grown on top of LZO at annealing temperatures of 1000 °C. Both layers revealed a very good in-plane alignment and are textured up to the surfaces. These results, obtained using new precursor solutions, which are simple in preparation, are very promising for further development of low cost buffer layer architectures for YBCO coated conductors.

Knoth, Kerstin; Schlobach, Brigitte; Hühne, Ruben; Schultz, Ludwig; Holzapfel, Bernhard

2005-10-01

53

An experimental study of the solubility of magnetite in sodium acetate solutions  

SciTech Connect

The solubility of commercial magnetite was studied by the batch method from 100{degrees} to 250{degrees}C at pressures of 250 and 1250 bar in the presence of aqueous acetic acid and sodium acetate. Problems associated with such solubility measurements are discussed. Independent potentiometric studies were carried out to determine the formation constants of ferrous acetate and chloride complexes to ca. 300{degrees}C. These results are discussed with emphasis on the speciation of iron(II) within solutions containing chloride and acetate ions equilibrated with magnetite. The isocoulombic approach is used to extrapolate the measured temperature dependencies of the equilibrium constants for the complexation of iron(II) by chloride, acetate and hydroxide ions.

Palmer, D.A.; Drummond, S.E. Jr.

1992-01-01

54

Highly textured La2Zr2O7 buffer layers for YBCO-coated conductors prepared by chemical solution deposition  

NASA Astrophysics Data System (ADS)

Recent results of La2Zr2O7 (LZO) buffer layer development for YBa2Cu3O7-x (YBCO-) coated conductors are presented. The major achievement is the development of a new precursor solution starting from 2,4-pentanedionates of lanthanum and zirconium leading to the formation of highly textured LZO buffer layers at low annealing temperatures. The preparation of the precursor solution using only a carboxylic acid as the solvent is simple and can be carried out at room temperature under atmospheric conditions. Reproducible highly textured buffer layers were obtained at annealing temperatures as low as 900 °C. The simplicity of the precursor solution preparation and the low annealing temperature (similar to the processing temperature of the YBCO layer) for preparation of an LZO buffer layer are the main advantages of this new process for cost-effective buffer layer deposition on Ni-RABiTS (rolling-assisted biaxially textured substrates).

Knoth, Kerstin; Hühne, Ruben; Oswald, Steffen; Schultz, Ludwig; Holzapfel, Bernhard

2005-03-01

55

Effects of Buffered Deglycerolization Solutions on the 21-Day Post-Thaw Preservation of Red Blood Cells.  

National Technical Information Service (NTIS)

Fresh-frozen or rejuvenated-frozen red cells were deglycerolized by centrifugal washing. The effects of phosphate buffering of the wash solutions on the pH of the washed cell suspension was examined. Buffering raised the red cell pH, and the positive effe...

G. L. Moore M. E. Ledford

1993-01-01

56

Kinetics of hydroxyapatite dissolution in acetic, lactic, and phosphoric acid solutions  

Microsoft Academic Search

Summary The present study was undertaken in an attempt to relate the kinetics of hydroxyapatite dissolution to solution parameters, under experimental conditions relevant to the dental caries process. Thus, the dissolution of hydroxyapatite was studied in acetic, lactic, and dilute phosphoric acid solutions having initial pH values from 4 to 6. Rates of dissolution and the corresponding degree of saturation

H. C. Margolis; E. C. Moreno

1992-01-01

57

An experimental study of copper(I)-chloride and copper(I)-acetate complexing in hydrothermal solutions between 50°C and 250°C and vapor-saturated pressure  

NASA Astrophysics Data System (ADS)

The transport of copper is affected by complexing with ligands such as chloride, bisulphide and acetate. Many copper deposits are formed from hydrothermal waters and brines and in order to understand their formation we need thermodynamic properties of aqueous copper species. The solubility of cuprite experiments in pH-buffered acetate and chloride solutions was determined at 50°C, 150°C and 250°C and water vapor saturated pressures. Chloride and acetate concentrations were varied using NaCl (0.001m to 2 m) and NaAc (0.1m to 2 m, where Ac refers to acetate). Measured copper concentrations varied between 0.0001 m and 0.2 m and show systematic increases with increasing temperature and acetate or chloride concentration. Logarithms of the formation constants (log K) of copper complexes were fitted by a simplex function minimization method, then speciation models and uncertainties of fitted log K values were examined by residual maps and speciation plots of experimental solutions. Interpretation of our experimental data shows that CuCl (aq), CuCl 2-, CuAc (aq) and CuAc 2- were present in our experiments at all temperatures. CuCl 32- is an important complex at 50°C, but cannot be detected unequivocally at 150°C and 250°C. This study presents the first experimentally-derived log K values for copper(I) acetate complexes (CuAc (aq) and CuAc 2-). The derived log K values of copper(I) chloride complexes (CuCl (aq) and CuCl 2-) are similar to recently published experimentally derived values (Xiao et al., 1998). Based on new log K values generated from this study, our calculations indicate that copper transport as acetate complexes is important in acetate-bearing fluids lacking competition of other ligands such as Cl - and HS -.

Liu, Weihua; McPhail, D. C.; Brugger, Joël

2001-09-01

58

A comparison of blood factor XII autoactivation in buffer, protein cocktail, serum, and plasma solutions.  

PubMed

Activation of blood plasma coagulation in vitro by contact with material surfaces is demonstrably dependent on plasma-volume-to-activator-surface-area ratio. The only plausible explanation consistent with current understanding of coagulation-cascade biochemistry is that procoagulant stimulus arising from the activation complex of the intrinsic pathway is dependent on activator surface area. And yet, it is herein shown that activation of the blood zymogen factor XII (Hageman factor, FXII) dissolved in buffer, protein cocktail, heat-denatured serum, and FXI deficient plasma does not exhibit activator surface-area dependence. Instead, a highly-variable burst of procoagulant-enzyme yield is measured that exhibits no measurable kinetics, sensitivity to mixing, or solution-temperature dependence. Thus, FXII activation in both buffer and protein-containing solutions does not exhibit characteristics of a biochemical reaction but rather appears to be a "mechanochemical" reaction induced by FXII molecule interactions with hydrophilic activator particles that do not formally adsorb blood proteins from solution. Results of this study strongly suggest that activator surface-area dependence observed in contact activation of plasma coagulation does not solely arise at the FXII activation step of the intrinsic pathway. PMID:23117212

Golas, Avantika; Yeh, Chyi-Huey Josh; Pitakjakpipop, Harit; Siedlecki, Christopher A; Vogler, Erwin A

2012-10-30

59

Thick lanthanum zirconate buffer layers from water-based precursor solutions on Ni-5%W substrates  

NASA Astrophysics Data System (ADS)

In this work, water-based precursor solutions suitable for dip-coating of thick La2Zr2O7 (LZO) buffer layers for coated conductors on Ni-5%W substrates were developed. The solutions were prepared based on chelate chemistry using water as the main solvent. The effect of polymer addition on the maximum crack-free thickness of the deposited films was investigated. This novel solution preparation method revealed the possibility to grow single, crack-free layers with thicknesses ranging 100-280 nm with good crystallinity and an in-plane grain misalignment with average FWHM of 6.55°. TEM studies illustrated the presence of nanovoids, typical for CSD-LZO films annealed under Ar-5%H2 gas flow. The appropriate buffer layer action of the film in preventing the Ni diffusion was studied using XPS. It was found that the Ni diffusion was restricted to the first 30 nm of a 140 nm thick film. The surface texture of the film was improved using a seed layer.

Narayanan, Vyshnavi; Lommens, Petra; de Buysser, Klaartje; Hühne, Ruben; van Driessche, Isabel

2011-11-01

60

Highly textured La2Zr2O7 buffer layers for YBCO-coated conductors prepared by chemical solution deposition  

Microsoft Academic Search

Recent results of La2Zr2O7 (LZO) buffer layer development for YBa2Cu3O7-x (YBCO-) coated conductors are presented. The major achievement is the development of a new precursor solution starting from 2,4-pentanedionates of lanthanum and zirconium leading to the formation of highly textured LZO buffer layers at low annealing temperatures. The preparation of the precursor solution using only a carboxylic acid as the

Kerstin Knoth; Ruben Hühne; Steffen Oswald; Ludwig Schultz; Bernhard Holzapfel

2005-01-01

61

Buffer capacity of biologics--from buffer salts to buffering by antibodies.  

PubMed

Controlling pH is essential for a variety of biopharmaceutical process steps. The chemical stability of biologics such as monoclonal antibodies is pH-dependent and slightly acidic conditions are favorable for stability in a number of cases. Since control of pH is widely provided by added buffer salts, the current study summarizes the buffer characteristics of acetate, citrate, histidine, succinate, and phosphate buffers. Experimentally derived values largely coincide with values calculated from a model that had been proposed in 1922 by van Slyke. As high concentrated protein formulations become more and more prevalent for biologics, the self-buffering potential of proteins becomes of relevance. The current study provides information on buffer characteristics for pH ranges down to 4.0 and up to 8.0 and shows that a monoclonal antibody at 50 mg/mL exhibits similar buffer capacity as 6 mM citrate or 14 mM histidine (pH 5.0-6.0). Buffer capacity of antibody solutions scales linearly with protein concentration up to more than 200 mg/mL. At a protein concentration of 220 mg/mL, the buffer capacity resembles the buffer capacity of 30 mM citrate or 50 mM histidine (pH 5.0-6.0). The buffer capacity of monoclonal antibodies is practically identical at the process relevant temperatures 5, 25, and 40°C. Changes in ionic strength of ?I=0.15, in contrast, can alter the buffer capacity up to 35%. In conclusion, due to efficient self-buffering by antibodies in the pH range of favored chemical stability, conventional buffer excipients could be dispensable for pH stabilization of high concentrated protein solutions. PMID:23296746

Karow, Anne R; Bahrenburg, Sven; Garidel, Patrick

2013-03-01

62

Rheological and hydrodynamic properties of cellulose acetate/ionic liquid solutions.  

PubMed

Rheological properties of cellulose acetate/1-ethyl-3-methylimidazolium acetate (EMIMAc) solutions are studied using shear dynamic and steady state rheology in a large range of polymer concentrations (from 0.1 to 10 wt.%) and temperatures (from 0 °C to 80 °C). Master plots for storage and loss moduli and for dynamic viscosity were built and shift parameters determined. Cellulose acetate/EMIMAc behaves as a classical polymer solution and obeys Cox-Merz law. Cellulose acetate intrinsic viscosity [?] was determined as a function of temperature and compared with the literature data for cellulose acetates dissolved in other solvents and cellulose dissolved in EMIMAc. Cellulose acetate intrinsic viscosity turned out to be much less temperature sensitive than that of cellulose. Specific viscosity-C[?] master plot was built: the slopes in log-log scale are 1.2 and 3.1 in dilute and semi-dilute regions, respectively. The activation energy as a function of concentration follows a power-law dependence. PMID:23399245

Rudaz, Cyrielle; Budtova, Tatiana

2012-11-30

63

[Continuous irrigation of the bladder with acetic acid solution and its therapeutic effect on candida-infection].  

PubMed

Our clinical experience with acetic acid solution in the treatment of candida infection of the bladder was confirmed by in vitro experiments. We apply continuous bladder irrigation with increasing concentrations of acetic acid solution up to pH 5.0. The majority of patients had received antibiotics or cytostatic drugs and suffered from chronic and malignant diseases. A case report is given with endoscopic documentation of the influence of acetic acid solution on the bladder. PMID:234644

Böcker, R; Fröhlich, G

1975-01-01

64

A resin-buffered nutrient solution for controlling metal speciation in the algal bottle assay.  

PubMed

Metal speciation in solution is uncontrolled during algal growth in the traditional algal bottle assay. A resin-buffered nutrient solution was developed to overcome this problem and this was applied to test the effect of chloride (Cl?) on cadmium (Cd) uptake. Standard nutrient solution was enriched with 40 mM of either NaNO? or NaCl, and was prepared to contain equal Cd²? but varying dissolved Cd due to the presence of CdCl(n)(2-n) complexes. Both solutions were subsequently used in an algal assay in 100 mL beakers that contained only the solution (designated "-R") or contained the solution together with a cation exchange sulfonate resin (2 g L?¹, designated "+R") as a deposit on the bottom of the beaker. Pseudokirchneriella subcapitata was grown for 72 h (1.4 × 10?-1.4 × 10? cells mL?¹) in stagnant solution and shaken three times a day. Growth was unaffected by the presence of the resin (p>0.05). The Cd concentrations in solution of the -R devices decreased with 50-58% of initial values due to Cd uptake. No such changes were found in the +R devices or in abiotic controls. Cd uptake was unaffected by either NaNO? or NaCl treatment in the +R device, confirming that Cd²? is the preferred Cd species in line with the general concept of metal bioavailability. In contrast, Cd uptake in the -R devices was two-fold larger in the NaCl treatment than in the NaNO? treatment (p<0.001), suggesting that CdCl(n)(2-n) complexes are bioavailable in this traditional set-up. However this bioavailability is partially, but not completely, an apparent one, because of the considerable depletion of solution ¹??Cd in this set-up. Resin-buffered solutions are advocated in the algal bottle assay to control trace metal supply and to better identify the role of metal complexes on bioavailability. PMID:22447105

Verheyen, L; Merckx, R; Smolders, E

2012-02-27

65

Influence of albumin on the electrochemical behaviour of Zr in phosphate buffered saline solutions.  

PubMed

The corrosion behaviour of Zr in phosphate buffered saline (PBS) solutions with various concentrations (0-4 g L(-1)) of albumin was studied by electrochemical techniques and surface analysis. Addition of albumin to PBS solutions moved the open circuit potential (OCP) to less nobler direction. OCP, polarization resistance and impedance increased and the corrosion current decreased over immersion duration. At early stages of immersion, the resistance was increased with the concentration of albumin because of the high adsorption kinetics of albumin on metal. After the long term immersion, the resistance in PBS without albumin was higher than PBS with albumin owing to the anodic dissolution effect of albumin on metal. According to the analysis of effective capacitances, a normal distribution of time-constants was proposed to estimate the surface film on Zr. A corrosion mechanism of Zr in PBS with different albumin was proposed based on electrochemical analysis. PMID:23180000

Wang, Lu-Ning; Huang, Xian-Qiu; Shinbine, Alyssa; Luo, Jing-Li

2012-11-21

66

Micellar Solubilization of Timobesone Acetate in Aqueous and Aqueous Propylene Glycol Solutions of Nonionic Surfactants  

Microsoft Academic Search

The micellar solubilization of timobesone acetate, a novel topical corticosteroid, was studied in aqueous and aqueous propylene glycol solutions of 1 to 5% nonionic surfactants at 25°C. The surfactants used were polyoxyethylene (POE) sorbitan monofatty acid esters (polysorbates), fatty acid esters (Myrj), and fatty alcohol ethers (Brij), as well as sucrose monolaurate (Crodesta SL40). The increase in the solubility of

John T. H. Ong; Elizabeth Manoukian

1988-01-01

67

Properties of acetic-acid alcohol-containing solutions of chitosan  

Microsoft Academic Search

It was shown that incorporation of ethyl alcohol in acetic-acid solutions of chitosan reduces their turbidity and intrinsic\\u000a viscosity and increases the dynamic viscosity more the higher the concentration of chitosan and the amount of alcohol added.

S. A. Uspenskii; G. A. Vikhoreva; A. N. Sonina; L. S. Gal’braikh

2010-01-01

68

Studies on the growth of chilomonas paramecium in inorganic and acetate solutions  

Microsoft Academic Search

Summary Cultures ofChilomonas paramecium in sodium acetate and inorganic salt solutions were examined for contaminating bacteria by cultural and microscopic methods. No bacteria could be found. Qualitative tests for nitrite and nitrate and quantitative estimation of the former indicated thatChilomonas cannot oxidize ammonia to nitrite or nitrate.

William Burrows

1938-01-01

69

Extraction of formic and acetic acids from aqueous solution by dynamic headspace-needle trap extraction  

Microsoft Academic Search

A combined method of dynamic headspace-needle trap sample preparation and gas chromatography for the determination of formic and acetic acids in aqueous solution was developed in this study. A needle extraction device coupled with a gas aspirating pump was intended to perform sampling and preconcentration of target compounds from aqueous sample before gas chromatographic analysis. The needle trap extraction (NTE)

Da-Wei Lou; Xinqing Lee; Janusz Pawliszyn

2008-01-01

70

Improved synthesis of 3-(dialkylaminomethyl)-indole in acetic acid aqueous solution under ultrasound irradiation.  

PubMed

Synthesis of Mannich bases related to gramine via Mannich reaction of secondary amine, formaldehyde and indole or N-methylindole can be carried out in 69-98% yields in acetic acid aqueous solution at 35°C under ultrasound irradiation. Compared with the method using stirring, the present procedure provided several advantages such as milder conditions, shorter reaction time and higher yield. PMID:20646952

Li, Ji-Tai; Sun, Shao-Feng; Sun, Ming-Xuan

2010-06-02

71

An experimental determination of ferrous chloride and acetate complexation in aqueous solutions to 300°C  

NASA Astrophysics Data System (ADS)

The formation of the monochloroiron(II) complex, FeCl + , was studied potentiometrically from 125 to 295°C at 25 degree intervals at one molal ionic strength in aqueous solutions containing acetic acid, sodium acetate, and sodium trifluoromethanesulfonate. In this method, competition between chloride and acetate ions for the ferrous cation resulted in a change in solution pH, which in turn was monitored in situ in a hydrogen-electrode, concentration cell. A simple empirical approach was used to extrapolate these formation quotients to infinite dilution. The resulting constants proved to be in excellent agreement with previous spectrophotometric results obtained from 25 to 200°C. Thus, the present study confirms the validity of the conclusions made based on these earlier data concerning the solubility of Fe-containing minerals in hydrothermal brines. Formation constants at infinite dilution for FeCl + are compared with the stability of ferrous acetate and hydroxide complexes. The original potentiometric titration data for ferrous acetate complex formation were combined in a new fit with values determined from the present study at unit ionic strength. Two empirical treatments (namely the isocoulombic method and the temperature/water density function) were considered for fitting and extrapolating the infinite dilution formation constants to 350°C.

Palmer, Donald A.; Hyde, K. E.

1993-04-01

72

Post-exercise gastric emptying of carbohydrate solutions determined using the 13 C acetate breath test  

Microsoft Academic Search

In an attempt to measure gastric emptying of carbohydrate solutions after exercise, we used the 13C acetate breath test to differentiate the gastric emptying of three approximately isoenergetic carbohydrate solutions (i.e. glucose, glucose polymer and sucrose) from each other and from water. On four separate occasions, six post-absorptive subjects walked on an inclined treadmill at 70% maximum oxygen uptake for

G. P. Leese; J. Bowtell; S. Mudambo; N. Reynolds; J. Thompson; C. M. Scrimgeour; M. J. Rennie

1995-01-01

73

Development of Solution Buffer Layers for RABiTS Based YBCO Coated Conductors  

SciTech Connect

The main objective of this research is to find a suitable alternate solution based seed layer for the standard RABiTS three-layer architecture of physical vapor deposited CeO2 cap/YSZ barrier/Y2O3 seed on Ni-5%W metal tape. In the present work, we have identified CeO2 buffer layer as a potential replacement for Y2O3 seeds. Using a metal-organic deposition (MOD) process, we have grown smooth, crack-free, epitaxial thin films of CeO2 (both pure and Zr, Cu and Gd-doped) directly on biaxially textured Ni-5W substrates in short lengths. Detailed XRD studies indicate that a single epitaxial CeO2 phase with slightly improved out-of-plane texture compared to the texture of underlying Ni-W substrates can be achieved in pure, undoped CeO2 samples. We have also demonstrated the growth of YSZ barrier layers on pure CeO2 seeds using sputtering. Both sputtered CeO2 cap layers and MOD-YBCO films were grown epitaxially on these YSZ-buffered MOD-CeO2/Ni-5W substrates. High critical currents per unit width, Ic of 264 A/cm (critical current density, Jc of 3.3 MA/cm2) at 77 K and 0.01 T was achieved for 0.8 m thick MOD-YBCO films grown on MOD-CeO2 seeds. These results indicate that CeO2 films can be grown directly on Ni-5W substrates and still support high performance YBCO coated conductors. This work holds promise for a route for producing low-cost buffer architecture for RABiTS based YBCO coated conductors.

Paranthaman, Mariappan Parans [ORNL; Qiu, Xiaofeng [ORNL; Kim, Kyunghoon [ORNL; Shi, D. [University of Cincinnati; Zhang, Yifei [ORNL; Li, Xiaoping [American Superconductor Corporation, Westborough, MA; Sathyamurthy, Srivatsan [ORNL; Thieme, C. L. H. [American Superconductor Corporation, Westborough, MA; Rupich, M. W. [American Superconductor Corporation, Westborough, MA

2010-01-01

74

Development of Solution Buffer Layers for RABiTS Based YBCO Coated Conductors  

SciTech Connect

Abstract The main objective of this research is to find a suitable alternate solution based seed layer for the standard RABiTS three-layer architecture of physical vapor deposited CeO cap/YSZ barrier/Y O seed on Ni-5%W metal tape. In the present work, we have identified CeO buffer layer as a potential replacement for Y O seeds. Using a metal-organic deposition (MOD) process, we have grown smooth, crack-free, epitaxial thin films of CeO (pure and Zr, Cu and Gd-doped) directly on biaxially textured Ni-5W substrates in short lengths. Detailed XRD studies indicate that a single epitaxial CeO phase with slightly improved out-of-plane texture compared to the texture of the underlying Ni-W substrates can be achieved in pure, undoped CeO samples. We have also demonstrated the growth of YSZ barrier layers on pure CeO seeds using sputtering. Both sputtered CeO cap layers and MOD-YBCO films were grown epitaxially on these YSZ-buffered MOD-CeO /Ni-5W substrates. High critical currents per unit width, of 264 A/cm (critical current density, of 3.3 MA/cm ) at 77 K and 0.01 T was achieved for 0.8 m thick MOD-YBCO films grown on MOD-CeO seeds. These results indicate that CeO films can be grown directly on Ni-5W substrates and still support high performance YBCO coated conductors. This work holds promise for a route for producing low-cost buffer architecture for RABiTS based YBCO coated conductors.

Paranthaman, Mariappan Parans [ORNL; Qiu, Xiaofeng [ORNL; List III, Frederick Alyious [ORNL; Zhang, Yifei [ORNL; Li, Xiaoping [American Superconductor Corporation, Westborough, MA; Sathyamurthy, Srivatsan [ORNL; Thieme, C. L. H. [American Superconductor Corporation, Westborough, MA; Rupich, M. W. [American Superconductor Corporation, Westborough, MA

2011-01-01

75

Critical zinc[sup +2] activities for sour orange determined with chelator-buffered nutrient solutions  

SciTech Connect

Chelator-buffered nutrient solutions were used to study the effect of different levels of Zn activity in the rhizosphere on growth and nutritive responses of various tissues of sour orange seedlings. The seedlings were grown for 3 months in a growth chamber in a hydroponic culture containing from 5 to 69 [mu]m and 5 to 101 [mu]m total Zn in Expts. 1 and 2, respectively. Zn[sup +2] activities were calculated with a computerized chemical equilibrium model, and buffered by inclusion of a chelator, diethylenetriamine pentaacetate (DTPA), at 74 and 44 [mu]m in excess of the sum of Fe, Mn, Zn, Cu, Ni, and Co in Expts. 1 and 2, respectively. The use of DTPA-buffered solutions proved successful in imposing varying degrees of Zn deficiency. The deficiency was confirmed by leaf symptomatology, leaf chemical analyses, i.e., <16 mg[center dot]kg[sup [minus]1] Zn, and responses to foliar sprays and application of Zn to the roots. Growth parameters varied in their sensitivity to Zn deficiency, i.e., root dry weight < leaf number and white root growth < stem dry weight < leaf dry weight < shoot elongation and leaf area. The critical activities, expressed as pZn = [minus]log(Zn[sup +2]), were [approximately]10.2 [+-] 0.2 for root dry weight, 10.1 [+-] 0.2 for leaf number and white root growth, 10.0 [+-] 0.2 for stem dry weight, 9.9 [+-] 0.2 for leaf dry weight, and 9.8 [+-] 0.2 for shoot growth and leaf area. Increases in growth were observed in response to Zn applications even in the absence of visible Zn-deficiency symptoms. Seedlings containing > 23 mg[center dot]kg[sup [minus]1] Zn in leaves did not respond to further additions of Zn to the nutrient solution. Zinc foliar sprays were less effective than Zn applications to the roots in alleviating severe Zn deficiency because foliar-absorbed Zn was not translocated from the top of the roots and thus could not correct Zn deficiency in the roots.

Swietlik, D.; Zhang, L. (Texas A M Univ., Weslaco, TX (United States))

1994-07-01

76

Effect of phosphate buffer on photodegradation reactions of riboflavin in aqueous solution.  

PubMed

The effect of phosphate buffer on aerobic photodegradation reactions of riboflavin (RF) at pH 7.0 has been studied. The photoproducts of the two major reactions, viz., intramolecular photoreduction and intramolecular photoaddition, have been determined by a specific multicomponent spectrophotometric method. The overall photodegradation of riboflavin in the presence of phosphate buffer involves the participation of both H2PO4-and HPO4(2-) species. The second-order rate constants for the H2PO4(-)-catalysed photodegradation of riboflavin (normal photolysis) to lumichrome (LC) and HPO4(2-)-catalysed photodegradation of riboflavin (photoaddition) to cyclodehydroriboflavin (CDRF) are 0.93 x 10(-4) and 4.0 x 10(-4) M(-1) s(-1), respectively. The addition of 0.25-2.00 M phosphate to RF solutions at pH 7.0 gives rise to RF-HPO4(2-) complex and hence the quenching of 4-36% fluorescence, respectively. This results in the suppression of normal photolysis leading to the formation of LC in favour of photoaddition to yield CDRF. The present study shows the involvement of H2PO4- anions in the base-catalysed degradation of riboflavin by normal photolysis vis-a-vis the involvement of HPO42- anions in photoaddition reactions of riboflavin suggested earlier [M. Schuman Jorns, G. Schollnhammer, P. Hemmerich, Intramolecular addition of the riboflavin side chain. Anion-catalysed neutral photochemistry, Eur. J. Biochem. 57 (1975) 35-48]. PMID:15708520

Ahmad, Iqbal; Fasihullah, Q; Vaid, Faiyaz H M

2005-03-01

77

Salt precipitation during the freeze-concentration of phosphate buffer solutions.  

PubMed

Salt precipitation during the freeze concentration of phosphate solutions was investigated by differential scanning calorimetry (DSC), in view of its practical importance in the cryopreservation or freeze-drying of biological materials. It was found that the fraction of salt precipitated depends on the initial salt concentration; it began to decrease with decreasing concentration at approx. 1 M. Salt precipitation also depends on the cooling rate. In some cases, cooling at approx. 10(3) degree min-1 inhibited salt precipitation which had been observed during slow cooling (0.62 degree min-1), without, however, affecting the shape of the ice melting endotherm. In the case of ternary phosphate buffers, the fraction of salt precipitating depends on the salt composition as well as the initial concentration and cooling rate. Near the composition of the ternary eutectic or the composition where two salts are present at the same concentration, salts were prevented from precipitation. PMID:2611352

Murase, N; Franks, F

1989-11-01

78

Surface Morphology of Radiation-Grafted Binary Copolymers Measured in Buffer Solution under Swelling Condition  

NASA Astrophysics Data System (ADS)

pH-dependent binary graft copolymers, [polypropylene (PP)-g-2-(dimethylamino)ethylmethacrylate (DMAEMA)-g-N-isopropylacrylamide (NIPAAm) and (PP-g-4-vinylpyridine (4VP))-g-NIPAAm], synthesized by a two-step gamma-irradiation method, were characterized in terms of surface morphology under swelling condition. A confocal laser microscope with a water-immersion objective lens was employed for noncontact surface profile measurement of an extremely soft surface. Surface morphology was significantly different between these two binary copolymers, suggesting that the surface morphology of the binary copolymer reflected that of the first graft layer. Surface roughness was also analyzed as a function of the pH of the swelling buffer solution. Surface roughness increased with swelling ratio, and it further increased at lower pH, consistent with the results of a swelling ratio experiment previously reported.

Meléndez-Ortiz, Hector Ivan; Bucio, Emilio; Isoshima, Takashi; Ito, Hiromi; Hara, Masahiko

2010-01-01

79

Thermodynamic and transport properties of l-serine and l-threonine in aqueous sodium acetate and magnesium acetate solutions at T = 298.15 K  

Microsoft Academic Search

The apparent molar volumes, V2,?, apparent molar adiabatic compressibilities, ?S,2,?, and relative viscosities, ?r, of l-serine and l-threonine in different concentrations of aqueous sodium acetate and magnesium acetate solutions at T=298.15K have been obtained from the measurements of densities, speed of sound, and flow time, respectively. These data are used to derive the partial molar volumes, V2?, partial molar adiabatic

T. S. Banipal; Damanjit Kaur; P. K. Banipal; Gagandeep Singh

2007-01-01

80

Methyltrimethoxysilane-insulated piezoelectric microcantilevers for direct, all-electrical biodetection in buffered aqueous solutions  

NASA Astrophysics Data System (ADS)

We have examined coating (PbMg1/3Nb2/3O3)0.63-(PbTiO3)0.37 (PMN-PT)/tin piezoelectric microcantilever sensors (PEMSs) with a thin methyltrimethoxysilane (MTMS) by a simple solution method to electrically insulate the PEMS for biodetection in phosphate buffered saline (PBS) solutions. The PMN-PT/tin PEMSs were constructed using PMN-PT freestanding films that exhibited an electric-field-enhanced giant piezoelectric coefficient. The insulation procedure involved spin coatings of MTMS followed by cross-linking in water, which yielded a coating layer of about 10 nm in thickness on the tin side of the PEMS. We showed that the MTMS-insulated PMN-PT/tin PEMSs were capable of electrical self-excitation and self-sensing with a stable resonance spectrum exhibiting a quality factor of Q=50 when submerged in 0.1M PBS solution. Direct, all-electrical, in situ detection of Escherichia coli O157:H7 at various concentrations was demonstrated at a flow rate of 0.5 ml/min. A MTMS-insulated PMN-PT/tin PEMS 725 ?m long consisting of a 22-?m-thick PMN-PT layer and a 6-?m-thick tin layer exhibited a mass detection sensitivity ?m/?f=-3+/-2×10-12 g/Hz and a concentration sensitivity of better than 100 cells/ml in less than 1 ml of liquid.

Capobianco, Joseph A.; Shih, Wan Y.; Shih, Wei-Heng

2006-12-01

81

The potentiometric determination of stability constants for zinc acetate complexes in aqueous solutions to 295°C  

NASA Astrophysics Data System (ADS)

A potentiometric method was used to determine the formation quotients of zinc acetate complexes in aqueous solutions from 50 to 295°C at ionic strengths of 0.03,0.3, and 1.0 m. The potentiometric titrations were carried out in an externally heated, Teflon-lined concentration cell fitted with hydrogen electrodes. Formal sodium acetate concentrations of the experimental solutions ranged from 0.001 to 0. 1 m with acetic acid to sodium acetate ratios ranging from 30 to 300. Sodium trifluoromethanesulfonate (F3CSO3Na) was used as a supporting electrolyte. Stoichiometries and formation quotients for the complexes ZnCH3COO+, Zn(CH3COO)2, and Zn(CH3COO)?3 were derived from the titration data by regression analysis. Stability constants at infinite dilution (Kn) and other relevant thermodynamic quantities were calculated for these three complexes. Logarithms for the formation constants of the general reaction Zn2+ + nCH3COO? = Zn(CH3COO)n2?n are n = 1?(1.9 ± 0.2, 50°C), (2.3 ± 0.1, 100°C), (2.8 ± 0.1, 150°C), (3.5 ± 0.1, 200°C), (4.3 ± 0.2, 250°C), (5.3 ± 0.3, 300°C); n = 2?(3.4 ± 0.1, 50°C), (4.0 ± 0.1, 100°C), (4.83 ± 0.09, 150°C), (5.9 ± 0.1, 200°C), (7.1 ± 0.1, 250°C), (8.7 ± 0.2, 300°C); n = 3?(4.1 ± 0.3, 50°C), (4.7 ± 0.3, 100°C), (5.5 ± 0.3, 150°C), (6.6 ± 0.3, 200°C), (7.9 ± 0.3, 250°C), (9.4 ± 0.3, 300°C). Calculations of zinc speciation in acetate-chloride solutions show that zinc acetate complexes should have an importance similar to zinc chloride complexes in high acetate waters where chloride to acetate molal ratios are less than about 10.

Glordano, Thomas H.; Drummond, S. E.

1991-09-01

82

Catalytic Deprotection of Acetals In Strongly Basic Solution Usinga Self-Assembled Supramolecular 'Nanozyme'  

SciTech Connect

Acetals are among the most commonly used protecting groups for aldehydes and ketones in organic synthesis due to their ease of installation and resistance to cleavage in neutral or basic solution.[1] The common methods for hydrolyzing acetals almost always involve the use of either Broensted acid or Lewis acid catalysts.[2] Usually aqueous acids or organic solutions acidified with organic or inorganic acids have been used for reconversion of the acetal functionality to the corresponding carbonyl group; however, recently a number of reports have documented a variety of strategies for acetal cleavage under mild conditions. These include the use of Lewis acids such as bismuth(III)[3] or cerium(IV),[4, 5] functionalized silica gel, such as silica sulfuric acid[6] or silica-supported pyridinium p-toluene sulfonate,[7] or the use of silicon-based reagents such as TESOTf-2,6-Lutidine.[8] Despite these mild reagents, all of the above conditions require either added acid or overall acidic media. Marko and co-workers recently reported the first example of acetal deprotection under mildly basic conditions using catalytic cerium ammonium nitrate at pH 8 in a water-acetonitrile solution.[5] Also recently, Rao and co-workers described a purely aqueous system at neutral pH for the deprotection of acetals using {beta}-cyclodextrin as the catalyst.[9] Herein, we report the hydrolysis of acetals in strongly basic aqueous solution using a self-assembled supramolecular host as the catalyst. During the last decade, we have used metal-ligand interactions for the formation of well-defined supramolecular assemblies with the stoichiometry M{sub 4}L{sub 6}6 (M = Ga{sup III} (1 refers to K{sub 12}[Ga{sub 4}L{sub 6}]), Al{sup III}, In{sup III}, Fe{sup III}, Ti{sup IV}, or Ge{sup IV}, L = N,N{prime}-bis(2,3-dihydroxybenzoyl)-1,5-diaminonaphthalene) (Figure 1).[10] The metal ions occupy the vertices of the tetrahedron and the bisbidentate catecholamide ligands span the edges. The strong mechanical coupling of the ligands transfers the chirality from one metal center to the other, thereby requiring the {Delta}{Delta}{Delta}{Delta} or {Lambda}{Lambda}{Lambda}{Lambda} configurations of the assembly. While the 12- overall charge imparts water solubility, the naphthalene walls of the assembly provide a hydrophobic environment which is isolated from the bulk aqueous solution. This hydrophobic cavity has been utilized to kinetically stabilize a variety of water-sensitive guests such as tropylium,[11] iminium ions,[12] diazonium ions,[13] and reactive phosphonium species.[14] Furthermore, 1 has been used to encapsulate catalysts[15] for organic transformations as well as act as a catalyst for the 3-aza-Cope rearrangement of enammonium substrates[16] and the hydrolysis of acid-labile orthoformates.[17] Our recent work using 1 as a catalyst for orthoformate hydrolysis prompted our investigation of the ability of 1 to catalyze the deprotection of acetals (Scheme 1). With the ability of 1 to favor encapsulation of monocationic guests, we anticipated that the rates of acetal hydrolysis could be accelerated by stabilization of any of the cationic protonated intermediates along the mechanistic pathway upon encapsulation in 1. In contrast to the stability of 2,2-dimethoxypropane in H{sub 2}O at pH 10, addition of the acetal to a solution of 1 at this pH quickly yielded the products of hydrolysis (acetone and methanol). Addition of a strongly binding inhibitor for the interior cavity of 1, such as NEt{sub 4}{sup +} (log (K{sub a}) = 4.55), inhibited the overall reaction, confirming that 1 is active in the catalysis.

Pluth, Michael D.; Bergman, Robert G.; Raymond, Kenneth N.

2007-07-26

83

BIOKID: Randomized controlled trial comparing bicarbonate and lactate buffer in biocompatible peritoneal dialysis solutions in children [ISRCTN81137991  

PubMed Central

Background Peritoneal dialysis (PD) is the preferred dialysis modality in children. Its major drawback is the limited technique survival due to infections and progressive ultrafiltration failure. Conventional PD solutions exert marked acute and chronic toxicity to local tissues. Prolonged exposure is associated with severe histopathological alterations including vasculopathy, neoangiogenesis, submesothelial fibrosis and a gradual loss of the mesothelial cell layer. Recently, more biocompatible PD solutions containing reduced amounts of toxic glucose degradation products (GDPs) and buffered at neutral pH have been introduced into clinical practice. These solutions contain lactate, bicarbonate or a combination of both as buffer substance. Increasing evidence from clinical trials in adults and children suggests that the new PD fluids may allow for better long-term preservation of peritoneal morphology and function. However, the relative importance of the buffer in neutral-pH, low-GDP fluids is still unclear. In vitro, lactate is cytotoxic and vasoactive at the concentrations used in PD fluids. The BIOKID trial is designed to clarify the clinical significance of the buffer choice in biocompatible PD fluids. Methods/design The objective of the study is to test the hypothesis that bicarbonate based PD solutions may allow for a better preservation of peritoneal transport characteristics in children than solutions containing lactate buffer. Secondary objectives are to assess any impact of the buffer system on acid-base status, peritoneal tissue integrity and the incidence and severity of peritonitis. After a run-in period of 2 months during which a targeted cohort of 60 patients is treated with a conventional, lactate buffered, acidic, GDP containing PD fluid, patients will be stratified according to residual renal function and type of phosphate binding medication and randomized to receive either the lactate-containing Balance solution or the bicarbonate-buffered Bicavera® solution for a period of 10 months. Patients will be monitored by monthly physical and laboratory examinations. Peritoneal equilibration tests, 24-h dialysate and urine collections will be performed 4 times. Peritoneal biopsies will be obtained on occasion of intraabdominal surgery. Changes in small solute transport rates, markers of peritoneal tissue turnover in the effluent, acid-base status and peritonitis rates and severity will be analyzed.

Nau, Barbara; Schmitt, Claus P; Almeida, Margarida; Arbeiter, Klaus; Ardissino, Gianluigi; Bonzel, Klaus E; Edefonti, Alberto; Fischbach, Michel; Haluany, Karin; Misselwitz, Joachim; Kemper, Markus J; Ronnholm, Kai; Wygoda, Simone; Schaefer, Franz

2004-01-01

84

Ozonation of trichloroethylene in acetic acid solution with soluble and solid humic acid.  

PubMed

The combined flushing and oxidation process using acetic acid and ozone has been used successfully to remove trichloroethylene (TCE) completely from contaminated soil. In this study, the effects of humic acid, a fraction of the organic matter in soil, over the performance of TCE decomposition was evaluated. TCE decomposition by ozone was enhanced by the presence of humic acid at concentrations lower than 8mgCL(-1) and then inhibited at higher concentrations. It is possible that the presence of the soluble humic acid fraction during the ozonation of TCE in acetic acid solutions produces hydroxyl radicals during the TCE ozonation which appears to be the reason for the enhanced TCE decomposition rate. Solid humic acid reduced TCE decomposition rate by acting as an ozone scavenger. Similarly, sorbed TCE reduced the amount of TCE available for decomposition by ozone in solution. PMID:18511186

Alcántara-Garduño, Martha E; Okuda, Tetsuji; Nishijima, Wataru; Okada, Mitsumasa

2008-03-30

85

Ethylene vinyl acetate\\/expanded graphite nanocomposites by solution intercalation: preparation, characterization and properties  

Microsoft Academic Search

Nanodimensional reinforcing agents are introduced to polymer matrices to improve properties at very low loading. Natural graphite\\u000a (NG) as such is not reinforcing in nature. But when modified to expanded graphite (EG) by high temperature heat treatment,\\u000a this may be used as reinforcing nanofiller. In the present study, ethylene vinyl acetate (EVA) was reinforced with EG by solution\\u000a intercalation, and

Jinu Jacob George; Anil K. Bhowmick

2008-01-01

86

Crystallization process of cubic ZrO 2 in calcium acetate solution  

Microsoft Academic Search

Ultrafine powders of cubic ZrO2 were obtained at about 270° C by heating hydrated amorphous ZrO2 in greater than 0.2 molal calcium acetate solutions. Ca2+ ions played a role as nucleii for crystallization and were introduced into distinct sites of the crystalline phases, that is, substituted for Zr4+ ions. Mn2+ ions produced almost the same effects on the crystallization of

H. Imishizawa; T. Tani; K. Matsuoka

1984-01-01

87

La 2Zr 2O 7 and Ce–Gd–O buffer layers for YBCO coated conductors using chemical solution deposition  

Microsoft Academic Search

Biaxially textured La2Zr2O7 (LZO) and Ce–Gd–O (CGO) buffer layers were grown on Ni-RABiTS (rolling-assisted biaxially textured substrates) to obtain suitable buffer layer architectures for YBa2Cu3O7?x (YBCO) coated conductors. Both buffer systems were prepared using newly developed precursor solutions containing a simple carboxylic acid as solvent. Reproducible highly textured LZO buffer layers were obtained at annealing temperatures as low as 900°C.

Kerstin Knoth; Brigitte Schlobach; Ruben Hühne; Ludwig Schultz; Bernhard Holzapfel

2005-01-01

88

Determination of the stability of laser deposited apatite coatings in phosphate buffered saline solution using Fourier transform infrared (FTIR) spectroscopy  

Microsoft Academic Search

We report the use of grazing angle Fourier transform infrared spectroscopy for determination of the stability to erosion of hydroxyapatite coatings. A series of coatings were deposited by pulsed laser ablation onto titanium foils. The coatings were exposed to a phosphate buffered saline solution, and FTIR spectroscopy was used to monitor the depletion of infrared bands associated with phosphate moieties

E. N Antonov; V. N Bagratashvili; V. K Popov; E. N Sobol; S. M Howdle

1996-01-01

89

THE EFFECT OF THE PH OF PH BUFFERED NUTRIENT SOLUTIONS ON NICKEL HYPERACCUMULATION BY ALYSSUM CORSICUM AND BERKHEYA CODDII  

Technology Transfer Automated Retrieval System (TEKTRAN)

It is hypothesized that plant hyperaccumulation of Ni evolved as a defense mechanism against diseases and insects. Two hyperaccumulators, Alyssum corsicum and Berkheya coddii, were compared to cabbage (Brassica oleracea) grown in MES-HEPES buffered nutrient solutions and maintained at four pH levels...

90

Amidolytic, procoagulant, and activation-suppressing proteins produced by contact activation of blood factor XII in buffer solution  

Microsoft Academic Search

The relative proportions of enzymes with amidolytic or procoagulant activity produced by contact activation of the blood zymogen factor XII (FXII, Hageman factor) in buffer solution depends on activator surface chemistry\\/energy. As a consequence, chromogenic assay of amidolytic activity (cleavage of amino acid bonds in s-2302 chromogen) does not correlate with the traditional plasma coagulation time assay for procoagulant activity

Avantika Golas; Chyi-Huey Joshua Yeh; Christopher A. Siedlecki; Erwin A. Vogler

2011-01-01

91

Viscosity Behavior of ?-Amino Acids in Acetate Salt Solutions at Temperatures (303.15 to 323.15) K  

NASA Astrophysics Data System (ADS)

Viscosities of l-lysine monohydrochloride, l-histidine, and l-arginine in 1 m (mol · kg-1) aqueous solutions of sodium acetate, potassium acetate, and calcium acetate salts has been determined at (303.15, 308.15, 313.15, 318.15, and 323.15) K. The Falkenhagen coefficient, A, and Jones-Dole coefficient, B, relative viscosity, and specific viscosity of the solutions have also been determined using the measured viscosities. The results are interpreted in terms of solute-solute and solute-solvent interactions occurring in the system under investigation and also discussed in terms of the structure-making/breaking ability of the solute in these salt solutions. The structure making/breaking abilities of the solutes in the studied systems are strongly influenced by temperature.

Siddique, Jamal Akhter; Naqvi, Saeeda

2012-01-01

92

Understanding the dissolution of ?-zein in aqueous ethanol and acetic acid solutions.  

PubMed

Zein is a corn prolamin that has broad industrial applications because of its unique physical properties. Currently, the high cost of extraction and purification, which is directly related to the dispersion of zein in different solvents, is the major bottleneck of the zein industry. Solution behaviors of zein have been studied for a long time. However, the physical nature of zein in different solvents remains unclear. In this study, small-angle X-ray scattering (SAXS), static light scattering (SLS), and rheology were combined to study the structure and protein-solvent interaction of ?-zein in both acetic acid and aqueous ethanol solutions. We found that the like-dissolve-like rule, the partial unfolding, and the protonation of zein are all critical to understanding the solution behaviors. Zein holds an elongated conformation (i.e., prolate ellipsoid) in all solutions, as revealed from SAXS data. There is an "aging effect" for zein in aqueous ethanol solutions, as evidenced by the transition of Newtonian rheological profiles for fresh zein solutions to the non-Newtonian shear thinning behavior for zein solutions after storage at room temperature for 24 h. Such shear thinning behavior becomes more pronounced for zein solutions at higher concentrations. The SLS results clearly show that acetic acid is a better solvent to dissolve zein than aqueous ethanol solution, as supported by a more negative second virial coefficient. This is majorly caused by the protonation of the protein, which was further verified by the dissolution of zein in water (a nonsolvent for zein) with the addition of acids. PMID:22973883

Li, Yunqi; Li, Ji; Xia, Qiuyang; Zhang, Boce; Wang, Qin; Huang, Qingrong

2012-09-24

93

The Acid Hydrolysis Mechanism of Acetals Catalyzed by a Supramolecular Assembly in Basic Solution  

SciTech Connect

A self-assembled supramolecular host catalyzes the hydrolysis of acetals in basic aqueous solution. The mechanism of hydrolysis is consistent with the Michaelis-Menten kinetic model. Further investigation of the rate limiting step of the reaction revealed a negative entropy of activation ({Delta}S{double_dagger} = -9 cal mol{sup -1}K{sup -1}) and an inverse solvent isotope effect (k(H{sub 2}O)/k(D{sub 2}O) = 0.62). These data suggest that the mechanism of hydrolysis that takes place inside the assembly proceeds through an A-2 mechanism, in contrast to the A-1 mechanism operating in the uncatalyzed reaction. Comparison of the rates of acetal hydrolysis in the assembly with the rate of the reaction of unencapsulated substrates reveals rate accelerations of up to 980 over the background reaction for the substrate diethoxymethane.

Pluth, Michael D.; Bergman, Robert G.; Raymond, Kenneth N.

2008-09-24

94

Enhancement of the absorption of CO{sub 2} in alkaline buffer solutions: Joint action of two enhancers  

SciTech Connect

The authors measured the absorption of CO{sub 2} in alkaline 0.5 M/0.5 M sodium carbonate/bicarbonate buffers containing either saccharose and sodium arsenite or saccharose and formaldehyde. Absorption enhancement increased upon increasing the concentration of either of the catalysts, but the joint action of the two was always less than the sum of their individual effects, the difference being a function of the acidities and concentrations of the catalysts and the pH of the carbonate/bicarbonate buffer solution

Vazquez, G.; Chenlo, F.; Pereira, G.; Vazquez, P. [Univ. of Santiago de Compostela (Spain). Dept. of Chemical Engineering

1999-05-01

95

Better Preservation of Peritoneal Morphologic Features and Defense in Rats after Long-Term Exposure to a Bicarbonate\\/ Lactate-Buffered Solution  

Microsoft Academic Search

The long-term effects of a standard lactate-buffered dialysis fluid and a new, two-chamber, bicarbonate\\/lactate- buffered dialysis fluid (with fewer glucose degradation prod- ucts and a neutral pH) were compared in an in vivo peritoneal exposure model. Rats were given daily injections, via an access port, of 10 ml of standard solution or bicarbonate\\/lactate- buffered solution for 9 to 10 wk.

LIESBETH H. P. HEKKING; MOHAMMAD ZAREIE; BAS A. J. DRIESPRONG; DIRK FAICT; ANGELIQUE G. A. WELTEN; INGE DE GREEUW; INGE L. SCHADEE-EESTERMANS; CARIN E. G. HAVENITH; JACOB VAN DEN BORN; PIET M. TER WEE; ROBERT H. J. BEELEN

2001-01-01

96

Effect of phosphate buffer on photodegradation reactions of riboflavin in aqueous solution  

Microsoft Academic Search

The effect of phosphate buffer on aerobic photodegradation reactions of riboflavin (RF) at pH 7.0 has been studied. The photoproducts of the two major reactions, viz., intramolecular photoreduction and intramolecular photoaddition, have been determined by a specific multicomponent spectrophotometric method. The overall photodegradation of riboflavin in the presence of phosphate buffer involves the participation of both H2PO4-andHPO42- species. The second-order

Iqbal Ahmad; Q. Fasihullah; Faiyaz H. M. Vaid

2005-01-01

97

Evaluation of Four Buffer Solutions for Determining the Lime Requirement for Ohio Soils  

Microsoft Academic Search

Lime is used as a soil amendment to achieve the optimum pH suitable for good crop growth. Buffer pH (BpH) measurements have been calibrated to relate the linear drop in pH of the soil–buffer system to the amount of lime needed to neutralize soil to a certain pH level. The amount of lime required to neutralize soil acidity, called the

A. Viswakumar; R. W. Mullen; K. A. Diedrick; W. A. Dick; N. T. Basta

2010-01-01

98

Plant uptake of 14 C-EDTA, 14 C-Citrate, and 14 C-Histidine from chelator-buffered and conventional hydroponic solutions  

Microsoft Academic Search

Chelator-buffered hydroponic solutions provide low and buffered free-metal concentrations and allow the easy calculation of nutrient species expected in these solutions. Some researchers suspect that the solutions allow plant uptake of chelates and that this uptake explains the failure of the free-ion activity model using these solutions. To determine the amount and method of chelate uptake, swiss chard was grown

Paul F. Bell; M. J. McLaughlin; G. Cozens; D. P. Stevens; G. Owens; H. South

2003-01-01

99

Solubility of sulfur dioxide in aqueous solutions of acetic acid, sodium acetate, and ammonium acetate in the temperature range from 313 to 393 K at pressures up to 3.3 MPa: Experimental results and comparison with correlations/predictions  

SciTech Connect

In many chemical plants, for example in coal gasification processes or desulfurization equipment, sour gas absorption columns and sour water strippers are used to remove weak electrolyte gases like sulfur dioxide, hydrogen cyanide, hydrogen sulfide or carbon dioxide from aqueous solutions. The basic design of such equipment requires physico-chemical models to describe the phase equilibrium as well as the caloric properties of such mixtures. New experimental results for the solubility of sulfur dioxide in aqueous solutions of single solutes acetic acid, sodium acetate and ammonium acetate at temperatures from 313 to 393 K and total pressures up to 3.3 MPa are reported. Similar to the system sulfur dioxide-water, also in such systems with acetic acid and sodium or ammonium acetate a second (sulfur dioxide rich) liquid phase is observed at high sulfur dioxide concentrations. A model to describe the phase equilibrium is presented and calculated (i.e., predicted as well as correlated) phase equilibria are compared to the new experimental data.

Xia, J.; Rumpf, B.; Maurer, G. [Univ. Kaiserslautern (Germany). Lehrstuhl fuer Technische Thermodynamik

1999-03-01

100

Mesoporous ferrosilicates with high content of isolated iron species synthesized in mild buffer solution and their catalytic application  

Microsoft Academic Search

The mesoporous ferrosilicates with high content of framework iron species have been synthesized under mild acidic conditions (pH 4.4, buffer solution) by co-condensation of iron acetylacetonate and a mixture of tetraethoxysilane (TEOS) and sodium silicate using block copolymer Pluronic P123 as the template. The XRD, N2 sorption and TEM results show that the materials have well-ordered, two-dimensional, hexagonal mesoporous structure

Hongchuan Xin; Jian Liu; Fengtao Fan; Zhaochi Feng; Guoqing Jia; Qihua Yang

2008-01-01

101

New correlation for liquid hold-up of sodium citrate buffer solution in a Raschig ring packed column  

Microsoft Academic Search

Dynamic liquid hold-up was measured with an air\\/aqueous sodium citrate buffer solution at 20–40 °C, and an air\\/water system at 23 °C, in a 0.1 m diameter\\/1 m high glass column covered by a heat-isolating vacuum jacket and packed with 0.012 m nominal size ceramic Raschig rings. The superficial gas velocity range was extended to 1.2 m s?1. Experimental results

I. Bágyi; E. Márki; E. Békássy-Molnár

1996-01-01

102

Studies on Dynamic Interfacial Tension between Crude Oil and Novel Surfactant Solutions with Buffered Alkali  

Microsoft Academic Search

Experimental studies have been conducted to elucidate the fundamental mechanisms for the lowering of dynamic interfacial tensions (DIT) between crude oil and surfactant flooding systems with buffered alkaline. A series of novel single component alkylmethylnaphthalene sulfonates (AMNS) including various carbon atom numbers of alkyl chains (hexyl, octyl, decyl, dodecyl, and tetradecyl), developed in our laboratory, were adopted. Moreover, surface tensions

Z. Zhao; F. Liu; W. Wang; Z. Li; W. Qiao; L. Cheng

2007-01-01

103

Effect of Initial Buffer Composition on pH Changes During Far-From-Equilibrium Freezing of Sodium Phosphate Buffer Solutions  

Microsoft Academic Search

Purpose. This study aims to assess the pH changes induced by salt precipitation during far-from-equilibrium freezing of sodium phosphate buffers as a function of buffer composition, under experimental conditions relevant to pharmaceutical applications—sample volumes larger than a few microliters, experiencing large degrees of undercooling and supersaturation.

Gerardo Gómez; Michael J Pikal; Naír Rodríguez-Hornedo

2001-01-01

104

Relationships between soil potassium supply characteristics based on soil solution concentration and buffer power and field responses of winter wheat and maize  

Microsoft Academic Search

The relationship between soil K supply, characterised by the soil solution K concentration and the soil K buffer power, and plant K status was investigated for field grown crops. The study was carried out in 15 K fertilisation trials with maize and wheat covering a wide range of agricultural soils and K level. Soil K buffer power was obtained through

A. Schneider; P. Castillon; S. Pellerin

2003-01-01

105

The Effect of Crystallizing and Non-crystallizing Cosolutes on Succinate Buffer Crystallization and the Consequent pH Shift in Frozen Solutions  

SciTech Connect

To effectively inhibit succinate buffer crystallization and the consequent pH changes in frozen solutions. Using differential scanning calorimetry (DSC) and X-ray diffractometry (XRD), the crystallization behavior of succinate buffer in the presence of either (i) a crystallizing (glycine, mannitol, trehalose) or (ii) a non-crystallizing cosolute (sucrose) was evaluated. Aqueous succinate buffer solutions, 50 or 200 mM, at pH values 4.0 or 6.0 were cooled from room temperature to -25 C at 0.5 C/min. The pH of the solution was measured as a function of temperature using a probe designed to function at low temperatures. The final lyophiles prepared from these solutions were characterized using synchrotron radiation. When the succinic acid solution buffered to pH 4.0, in the absence of a cosolute, was cooled, there was a pronounced shift in the freeze-concentrate pH. Glycine and mannitol, which have a tendency to crystallize in frozen solutions, remained amorphous when the initial pH was 6.0. Under this condition, they also inhibited buffer crystallization and prevented pH change. At pH 4.0 (50 mM initial concentration), glycine and mannitol crystallized and did not prevent pH change in frozen solutions. While sucrose, a non-crystallizing cosolute, did not completely prevent buffer crystallization, the extent of crystallization was reduced. Sucrose decomposition, based on XRD peaks attributable to {beta}-D-glucose, was observed in frozen buffer solutions with an initial pH of 4.0. Trehalose completely inhibited crystallization of the buffer components when the initial pH was 6.0 but not at pH 4.0. At the lower pH, the crystallization of both trehalose dihydrate and buffer components was evident. When retained amorphous, sucrose and trehalose effectively inhibited succinate buffer component crystallization and the consequent pH shift. However, when trehalose crystallized or sucrose degraded to yield a crystalline decomposition product, crystallization of buffer was observed. Similarly, glycine and mannitol, two widely used bulking agents, inhibited buffer component crystallization only when retained amorphous. In addition to stabilizing the active pharmaceutical ingredient, lyoprotectants may prevent solution pH shift by inhibiting buffer crystallization.

Sundaramurthi, Prakash; Suryanarayanan, Raj (UMM)

2011-09-06

106

Proposing buffer zones and simple technical solutions for safeguarding river water quality and public health  

NASA Astrophysics Data System (ADS)

Alfeios River Basin (ARB) constitutes one of the major hydrologic basins (?3650km2) of Peloponnisos peninsula in Southern Greece. It is drained by Alfeios River and its tributaries, such as Lousios, Ladhon, Erymanthos, Kladheos, Selinous etc. The present manuscript takes a closer look at the importance of tributary basins and focuses on Erymanthos sub-basin that covers about 360 km2. Erymanthos River springs from Erymanthos Mountain that reaches altitudes of 2200 m and discharges 10 m3/sec, approximately, during the winter period, presenting a sound decrease from half to about an order of magnitude during summertime. Two factors stand out as reasons to select Erymanthos sub-basin as a case study. First, the sub-basin presents a significant variety of ecosystems and comprises a very important river system, since Erymanthos Tributary satisfies, among other uses, drinking water supply for a great majority of citizens in the region. Second, authors' experience of the study area in Research Program Pythagoras II, funded by the European Social Fund (ESF) and the Operational Program for Educational and Vocational Training II (EPEAEK II) of Greece, offers a basis for better understanding of the real problems in the area. Erymanthos watershed, in fact, faces a lot of pressures, in several levels, provoked by human activities and Erymanthos Tributary is vulnerable to pollution. Recognizing the importance of clean water for healthy people, a developing economy, and a sustainable environment, the challenge of the present paper is elaborating human-induced pressures in the study area, analyzing their effects, estimating pollution factors and proposing integrated solutions/tools and a number of methodologies/initiatives used to overcome the problem of contaminating water supply in a catchment that lacks of wastewater treatment and disposal systems. The preservation of a good ecological status in Erymanthos River is not only a necessity for achieving the goals of EU Water Framework Directive (WFD) 2000/60, but a practical necessity for the safeguarding of public health and ecosystem health, in general. The present study aims at developing a simple methodology for assessing spatial distribution characteristics of pollution in Erymanthos catchment. Pollution loads at various sites in Erymanthos watershed were illustrated with Geographical Information System (GIS). Flow rates of Erymanthos River were also taken into consideration. Based on previous studies, in situ river discharges have been compared to simulated discharges in order to calibrate the rainfall-runoff model ENNS which can then predict future scenarios regarding the river flow rates with consideration of climate change effects. The goal of this study is to detect the pertinent points and suggest a) suitable buffer zones in areas with high pollution risk and b) simple technical works in order to prevent the main channel of Erymanthos River from direct polluting discharges. The above systems could also act supportively in groundwater enrichment, forest protection and soil erosion prevention. Authors believe that the results of the study could assist authorities and engineers to design and develop strategies of improving river water quality and safeguarding public health. The proposed measures may be applicable to other catchments as well.

Podimata, M. V.; Bekri, E. S.; Yannopoulos, P. C.

2012-04-01

107

Stability of curcumin in buffer solutions and characterization of its degradation products  

Microsoft Academic Search

The degradation kinetics of curcumin under various pH conditions and the stability of curcumin in physiological matrices were investigated. When curcumin was incubated in 0.1 M phosphate buffer and serum-free medium, pH 7.2 at 37°C, about 90% decomposed within 30 min. A series of pH conditions ranging from 3 to 10 were tested and the result showed that decomposition was

Ying-Jan Wang; Min-Hsiung Pan; Ann-Lii Cheng; Liang-In Lin; Yuan-Soon Ho; Chang-Yao Hsieh; Jen-Kun Lin

1997-01-01

108

Calorimetric and Diffractometric Evidence for the Sequential Crystallization of Buffer Components and the Consequential pH Swing in Frozen Solutions  

SciTech Connect

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{sub a2} was cooled from room temperature (RT), the freeze-concentrate pH first increased and then decreased. This was attributed to the sequential crystallization of succinic acid, monosodium succinate, and finally disodium succinate. When buffered to pH > pK{sub a2}, 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{sub 2}(CH{sub 2}COO){sub 2} {center_dot} 6H{sub 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.

Sundaramurthi, Prakash; Shalaev, Evgenyi; Suryanarayanan, Raj (Pfizer); (UMM)

2010-06-22

109

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

PubMed

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) was cooled from room temperature (RT), the freeze-concentrate pH first increased and then decreased. This was attributed to the sequential crystallization of succinic acid, monosodium succinate, and finally disodium succinate. When 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. PMID:20302316

Sundaramurthi, Prakash; Shalaev, Evgenyi; Suryanarayanan, Raj

2010-04-15

110

Characteristics of thin cellulose ester films spin-coated from acetone and ethyl acetate solutions  

Microsoft Academic Search

Spin-coated films of cellulose acetate (CA), cellulose acetate propionate (CAP), cellulose acetate butyrate (CAB) and carboxymethylcellulose\\u000a acetate butyrate (CMCAB) have been characterized by ellipsometry, atomic force microscopy (AFM) and contact angle measurements.\\u000a The films were spin-coated onto silicon wafers, a polar surface. Mean thickness values were determined by means of ellipsometry\\u000a and AFM as a function of polymer concentration in

J. Amim Jr; P. M. Kosaka; D. F. S. Petri

2008-01-01

111

Spectral fingerprint in X-ray absorption for hydrogen-bonded dimer formation of acetic acids in solution  

NASA Astrophysics Data System (ADS)

We have measured X-ray absorption spectra for acetic acid molecules in an organic solvent in order to study the effect of hydrogen-bonding formation. The spectral shapes distorted by saturation effect were compensated by using a new correction procedure for X-ray absorption based on the changes in the concentration of the samples. A resonance peak shift was observed when the acetic acid molecules formed a cyclic dimer in hexane solution, which is similar to the behavior of cluster molecules in vacuum. This is the first report on the XAS spectral changes due to cyclic dimer formation in a solution.

Horikawa, Y.; Arai, H.; Tokushima, T.; Shin, S.

2012-01-01

112

Effect of borate buffer on the photolysis of riboflavin in aqueous solution.  

PubMed

The photolysis of riboflavin (RF) in the presence of borate buffer (0.1-0.5M) at pH 8.0-10.5 has been studied using a specific multicomponent spectrophotometric method for the determination of RF and photoproducts, formylmethylflavin (FMF), lumichrome (LC) and lumiflavin (LF). The overall first-order rate constants for the photolysis of RF (1.55-4.36 x 10(-2)min(-1)) and the rate constants for the formation of FMF (1.16-3.52 x 10(-2)min(-1)) and LC (0.24-0.84 x 10(-2)min(-1)) have been determined. The values of all these rate constants decrease with an increase in buffer concentration suggesting the inhibition of photolysis reaction by borate species. The kinetic data support the formation of a RF-borate complex involving the ribityl side chain to cause the inhibition of photolysis. The second-order rate constants for the borate inhibited reaction range from 1.17-3.94 x 10(-2)M(-1)min(-1). The log k-pH profiles for the reaction at various buffer concentrations indicate a gradual increase in rate, with pH, up to 10 followed by a decrease in rate at pH 10.5 probably due to ionization of RF and quenching of fluorescence by borate species. A graph of second-order rate constants against pH is a sigmoid curve showing that the rate of photolysis increases with an increase in pH. The results suggest the involvement of excited singlet state, in addition to excited triplet state, in the formation of LC. PMID:18760621

Ahmad, Iqbal; Ahmed, Sofia; Sheraz, Muhammad Ali; Vaid, Faiyaz H M

2008-07-29

113

High-quality fiber fabrication in buffered hydrofluoric acid solution with ultrasonic agitation.  

PubMed

An etching method for preparing high-quality fiber-optic sensors using a buffered etchant with ultrasonic agitation is proposed. The effects of etching conditions on the etch rate and surface morphology of the etched fibers are investigated. The effect of surface roughness is discussed on the fibers' optical properties. Linear etching behavior and a smooth fiber surface can be repeatedly obtained by adjusting the ultrasonic power and etchant pH. The fibers' spectral quality is improved as the ratio of the pit depth to size decreases, and the fibers with smooth surfaces are more sensitive to a bacterial suspension than those with rough surfaces. PMID:23458795

Zhong, Nianbing; Liao, Qiang; Zhu, Xun; Wang, Yongzhong; Chen, Rong

2013-03-01

114

Highly selective recognition of acetate and bicarbonate by thiourea-functionalised inverse opal hydrogel in aqueous solution.  

PubMed

We have synthesised an inverse opal hydrogel functionalised with a thiourea moiety as an anion recognition site. The resulting hydrogel showed remarkable changes of its structural colour with respect to acetate and bicarbonate ions selectively in aqueous solution, indicating a potential as colorimetric sensing materials for hydrophilic anions. PMID:23238179

Kado, Shinpei; Otani, Haruka; Nakahara, Yoshio; Kimura, Keiichi

2013-01-30

115

Photoelectrochemical study of pitting on iron in borate buffer solution containing inhibitor  

SciTech Connect

The photoelectrochemical behavior and the susceptibility of iron to pitting in borate buffer containing chloride ions (Cl{sup {minus}}) were investigated in the presence and absence of inhibitor PC-604, which is a mixture of polyhydric alcohol phosphoric easter and polyphosphoric ester of various molecular weights. Measurements of the band gap (E{sub g}) of the passive film on iron showed inhibitor concentration and passivation time did not interfere with E{sub g}. Photocurrent and photocurrent transients increased with increasing inhibitor quantities and passivation times at constant potential. The decay time-constant of the photocurrent transient was investigated as a specific parameter of the film. Data showed this parameter was related to pitting susceptibility of the passive film on iron.

Yang, M.; Chen, L.; Cai, S. [Peking Univ., Beijing (China). Dept. of Chemistry

1997-01-01

116

Sol-gel preparation of ZnO films with extremely preferred orientation along (002) plane from zinc acetate solution  

Microsoft Academic Search

ZnO films with preferred orientation along the (002) plane were fabricated by the sol-gel method using Zn(CH3COO)2 · 2H2O as starting material. A homogeneous and stable solution was prepared by dissolving the zinc acetate in a solution of 2-methoxyethanol and monoethanolamine. ZnO films highly oriented along the (002) plane were obtained by preheating the dip-coating films at temperatures from 200°

Masashi Ohyama; Hiromitsu Kouzuka; Toshinobu Yoko

1997-01-01

117

Anodic oxidation of 3,4-dihydroxyphenylacetic acid on carbon electrodes in acetic acid solutions.  

PubMed

The electrochemical oxidation of 3,4-dihydroxyphenylacetic acid (DOPAC) on a carbon fiber microelectrode (CF) and a glassy carbon macroelectrode (GC) in glacial acetic acid solutions was investigated using voltammetric techniques. Voltammograms recorded at these electrodes show well-defined single waves or peaks. The proposed mechanism of the anodic oxidation of DOPAC consists of two successive one-electron one-proton steps. The loss of the first electron proceeds irreversibly and determines the overall rate of the electrode process. This stage is accompanied by the generation of an unstable phenoxyl radical in position 4 of the aromatic ring. The second stage of the electrode reaction produces substituted orto-quinone as the final product of the electrode process of DOPAC. DOPAC exhibits more antioxidative power than synthetic BHT and can be useful in food protection against reactive oxygen species. The results presented can help to explain biochemical and antioxidative properties of DOPAC in a living cell and can be useful in determination of this compound in real samples. PMID:20004625

Michalkiewicz, Slawomir; Skorupa, Agata

2009-12-03

118

Comparison of the photochemical behaviors of ?-tocopherol and its acetate in organic and aqueous micellar solutions.  

PubMed

Photoionization is known to take place when ?-tocopherol (TOH) is excited to the S(1) state in a polar medium. It has been previously suggested that TO(•) is formed only as a result of proton release by TOH(•+), a process that is expected to occur, in a protic solvent, on the subnanosecond time scale. Recent redeterminations of the molar absorption coefficients of e(aq)(–) (Hare J. Phys. Chem. A 2010, 114, 1766) and of TOH(•+) and TO(•) (Naqvi J. Phys. Chem. A 2010, 114, 10795) have paved the way for testing the above suggestion, even if subnanosecond time resolution is not available, since it implies the equality of [e(aq)(–)](0) and [TO(•)](0), where [···](0) denotes the concentration of the enclosed species immediately after a nanosecond laser pulse. Nanosecond pump-probe spectroscopy of TOH in aqueous micellar solution (AMS) and two organic solvents with similar polarities (acetonitrile and methanol) has revealed that prompt formation of TO(•) through dissociation (TOH + h? ? TO(•) + H(•)) is not negligible even in AMS. In acetonitrile, TOH(•+) and TO(•) are formed with comparable yields, and the former converts quantitatively into TO(•) within 15 ?s. In methanol, TO(•) was observed, but no evidence was found for electron ejection from TOH. Only one photoproduct, namely TO(•), could be detected when ?-tocopherol acetate (TOAc) was excited to the S(1) state in several polar and nonpolar solvents; TOAc has been found to be a more efficient energy degrader than TOH. PMID:21675787

Zhang, Ye; Yousef, Y A; Li, Heng; Melø, T B; Naqvi, K Razi

2011-06-30

119

Removal and recovery of furfural, 5-hydroxymethylfurfural, and acetic acid from aqueous solutions using a soluble polyelectrolyte.  

PubMed

In the cellulosic ethanol process, furfural, 5-hydroxymethylfurfural (HMF), and acetic acid are formed during the high temperature acidic pretreatment step needed to convert biomass into fermentable sugars. These compounds can inhibit cellulase enzymes and fermentation organisms at relatively low concentrations (? 1 g/L). Effective removal of these inhibitory compounds would allow the use of more severe pretreatment conditions to improve sugar yields and lead to more efficient fermentations; if recovered and purified, they could also be sold as valuable by-products. This study investigated the separation of aldhehydes (furfural and HMF) and organic acid (acetic acid) inhibitory compounds from simple aqueous solutions by using polyethyleneimene (PEI), a soluble cationic polyelectrolyte. PEI added to simple solutions of each inhibitor at a ratio of 1 mol of functional group to 1 mol inhibitor removed up to 89.1, 58.6, and 81.5 wt% of acetic acid, HMF, and furfural, respectively. Furfural and HMF were recovered after removal by washing the polyelectrolyte/inhibitor complex with dilute sulfuric acid solution. Recoveries up to 81.0 and 97.0 wt% were achieved for furfural and HMF, respectively. The interaction between PEI and acetic acid was easily disrupted by the addition of chloride ions, sulfate ions, or hydroxide ions. The use of soluble polymers for the removal and recovery of inhibitory compounds from biomass slurries is a promising approach to enhance the efficiency and economics of an envisioned biorefinery. PMID:21455937

Carter, Brian; Gilcrease, Patrick C; Menkhaus, Todd J

2011-04-14

120

Acid buffering a high pH soil for zinc diffusion  

Microsoft Academic Search

The effective use of an aqueous buffer solution of acetic acid and sodium acetate (1.0 M HOAc\\/1.4 M NaOAc, pH = 4.8) to lower the pH of a sand-attapulgite clay mixture from 9.4 to 4.8 is demonstrated. Soil buffering is necessary to prevent precipitation of Zn{sup 2+} as Zn(OH){sub 2(s)} during zinc diffusion tests. The choice of the acetic acid\\/sodium

Charles D. Shackelford; Todd E. Cotten; Kristina M. Rohal; Steven H. Strauss

1997-01-01

121

Effect of La2Zr2O7-buffered YSZ substrate on YBa2Cu3Oy thin films by chemical solution deposition  

NASA Astrophysics Data System (ADS)

Epitaxial YBa2Cu3Oy (YBCO) thin films have been fabricated by chemical solution deposition (CSD) on La2Zr2O7-buffered YSZ single crystal substrate, where the buffer layer has three kinds of morphology - flat surface, rough surface and pore surface. The effect of LZO buffer layer’s roughness on the YBCO films was evaluated by X-ray diffraction, scanning electron microscopy and temperature-dependent resistivity measurements. The flat surface of LZO layer is beneficial to highly epitaxial YBCO films and high critical current density.

Jin, Lihua; Yu, Zeming; Zhang, Yun; Wang, Yao; Yan, Guo; Li, Chengshan; Lu, Yafeng

2010-07-01

122

Chemical solution deposition of La2Zr2O7 and Y2Ti2O7 buffer layers on NiW substrates  

NASA Astrophysics Data System (ADS)

La2Zr2O7 and Y2Ti2O7 buffer layers with similar lattice constant and cubic structure were successfully deposited on NiW(2 0 0) substrates using propionic acid as unique chelate through chemical solution deposition method. The results showed that using 900 °C-annealing temperature one could obtain highly (4 0 0)-oriented LZO buffer layers with relatively sharp out-of-plane and in-plane orientation and flat microstructure; However, the YTO buffer layers with similar lattice constant with LZO and cubic structure were (2 2 2)-oriented although the YTO lattice constant and structure were similar with that of LZO.

Zhu, X. B.; Sun, Y. P.; Song, W. H.; Yang, J.; Gu, H. W.

2006-01-01

123

Chemical solution deposition of La2Zr2O7 and Y2Ti2O7 buffer layers on NiW substrates  

Microsoft Academic Search

La2Zr2O7 and Y2Ti2O7 buffer layers with similar lattice constant and cubic structure were successfully deposited on NiW(2 0 0) substrates using propionic acid as unique chelate through chemical solution deposition method. The results showed that using 900 °C-annealing temperature one could obtain highly (4 0 0)-oriented LZO buffer layers with relatively sharp out-of-plane and in-plane orientation and flat microstructure; However,

X. B. Zhu; Y. P. Sun; W. H. Song; J. Yang; H. W. Gu

2006-01-01

124

Interfacial energetics of globular-blood protein adsorption to a hydrophobic interface from aqueous-buffer solution  

PubMed Central

Adsorption isotherms of nine globular proteins with molecular weight (MW) spanning 10–1000?kDa confirm that interfacial energetics of protein adsorption to a hydrophobic solid/aqueous-buffer (solid–liquid, SL) interface are not fundamentally different than adsorption to the water–air (liquid–vapour, LV) interface. Adsorption dynamics dampen to a steady-state (equilibrium) within a 1?h observation time and protein adsorption appears to be reversible, following expectations of Gibbs' adsorption isotherm. Adsorption isotherms constructed from concentration-dependent advancing contact angles ?a of buffered-protein solutions on methyl-terminated, self-assembled monolayer surfaces show that maximum advancing spreading pressure, ?amax, falls within a relatively narrow 10

Krishnan, Anandi; Liu, Yi-Hsiu; Cha, Paul; Allara, David; Vogler, Erwin A

2005-01-01

125

PHOTOLUMINESCENT DISTINCTION AMONG PLANT LIFE FORMS USING PHOSPHATE BUFFERED SALINE EXTRACT SOLUTIONS  

Technology Transfer Automated Retrieval System (TEKTRAN)

Photoluminescence of plant extract solutions has been investigated for discrimination of plant life forms (grasses, forbs and shrubs) using principle componet analysis (PCA). Clippings from each of six plant species representing three different plant life forms potentially found in the diets of fre...

126

Host-guest stabilized room temperature phosphorescence in beta-cyclodextrin/ bromoalcohol solutions from 2-naphthyl-oxy-acetic acid and 1-naphthyl-acetic acid.  

PubMed

Room temperature phosphorescence (RTP) from 2-naphthyl-oxy-acetic acid (NOA) and 1-naphthyl-acetic acid (NAA), with stabilization by use of beta-cyclodextrin (beta-CD) as a host system, has been examined. 2-Bromoethanol and 2,3-dibromopropanol have been evaluated as external heavy atom perturbers to enhance the rate of intersystem crossing and, consequently, populating the triplet state for phosphorescence emission. The deoxygenation of the solutions was achieved chemically by use of sodium sulphite. The spectral characteristics of the phosphorescence emission from these relatively polar compounds and the optimization of the chemical variables involved are reported. The role of the bulkiness of the bromoalcohol employed, in comparison with the unoccupied space of the interior of the cyclodextrin cavity by the guest, is an important factor in the attainment of an effective RTP emission, and should be taken into account in the selection of the appropriate external heavy atom for the observation of RTP from other organic molecules of interest by this approach. 2,3-Dibromopropanol seems a more adequate bromoalcohol than 2-bromoethanol for the observation of RTP emission in the systems investigated. PMID:18965836

de la Pena, A M; Salinas, F; Gomez, M J; Sanchez-Pena, M; Duran-Meras, I

1993-11-01

127

Diffusion of ionizable solutes across planar lipid bilayer membranes: boundary-layer pH gradients and the effect of buffers.  

PubMed

The diffusion of weak acids or bases across planar lipid bilayer membranes results in aqueous boundary layer pH gradients. If not properly taken into account, such pH gradients will lead to errors in estimated membrane permeability coefficients, Pm. The role of the permeant concentration, the buffer capacity, and the physicochemical properties of both permeant and buffer on the magnitude and impact of such pH gradients have been explored. A theoretical model has been developed to describe the diffusion of both permeant and buffer species. Significant pH gradients develop depending on solution pH and the pKa's, concentrations, and Pm values of both permeant and buffer. The relative error in experimentally determined Pm values was calculated as the ratio, r, between apparent Pm values (obtained from flux measurements using an equation which neglected boundary layer pH gradients) and its true value. Simulated r values ranged from 1 (0% error) to < 0.01 (> 100% error) for weak acids, decreasing with decreasing buffer capacity and increasing solute flux. The buffer capacity required for an r > 0.95 was calculated versus pH for permeants varying in pKa and Pm. Membrane-permeable buffers significantly reduce boundary layer pH gradients through a feedback effect due to buffer cotransport. Apparent Pm values of p-hydroxymethyl benzoic acid across lecithin bilayer membranes at 25 degrees C were obtained as a function of permeant concentration in various buffers [glycolic, 2-(N-morpholino)ethane-sulfonic, and formic acids]. Predictions agreed closely with experimental fluxes. PMID:8290481

Xiang, T X; Anderson, B D

1993-11-01

128

Characteristics of Porous Cellulose Acetate Membranes for the Separation of Some Inorganic Salts in Aqueous Solution.  

National Technical Information Service (NTIS)

Experimental results are presented to illustrate the effect of operating variables on the separation and flow characteristics of porous cellulose acetate membranes. The results are discussed from the point of view of the preferential sorption and capillar...

S. Sourirajan

1964-01-01

129

Recovery of acetic acid from dilute aqueous solutions using catalytic dehydrative esterification with ethanol.  

PubMed

We have developed a direct esterification of aqueous acetic acid with ethanol (molar ratio=1:1) catalyzed by polystyrene-supported or homogeneous sulfonic acids toward the recovery of acetic acid from wastewater in chemical plants. The equilibrium yield was significantly increased by the addition of toluene, which had a high ability to extract ethyl acetate from the aqueous phase. It was shown that low-loading and alkylated polystyrene-supported sulfonic acid efficiently accelerated the reaction. These results suggest that the construction of hydrophobic reaction environments in water was critical in improving the chemical yield. Addition of inorganic salts was also effective for the reaction under not only biphasic conditions (toluene-water) but also toluene-free conditions, because the mutual solubility of ethyl acetate and water was suppressed by the salting-out effect. Among the tested salts, CaCl(2) was found to be the most suitable for this reaction system. PMID:23290939

Yagyu, Daisuke; Ohishi, Tetsuo; Igarashi, Takeshi; Okumura, Yoshikuni; Nakajo, Tetsuo; Mori, Yuichiro; Kobayashi, Sh?

2013-01-03

130

Decontamination of aquatic vegetable leaves by removing trace toxic metals during pickling process with acetic acid solution.  

PubMed

The heavy-metal content of aquatic plants is mainly dependent upon their ecological system. This study indicated that although the toxic heavy-metal contents could be above the recommended maximum levels depending upon their concentrations in growing water, they can be decontaminated by pickling with 5% acetic acid solution. Almost all Cd, Hg, Ba, or Sb and 99.5% Pb, 96.7% Ag, or 97.1% Al were removed from Water Spinach leaves by soaking in acetic acid solution. For Water-Shield leaves, almost all Cd, Hg, Pb, Ba, or Sb and 95.0% Ag or 96.1% Al were removed. For Watercress leaves, almost all Cd, Hg, Ba, or Sb and 99.0% Pb or 99.7% Ag were removed. For Water Hyacinth leaves, almost all Cd, Ba, or Sb and 99.0% Hg, 98.5% Pb, 95.0% Ag, or 98.7% Al were removed. PMID:21888602

Wu, Wenbiao; Yang, Yixing

131

Electrochemical examination of surface films formed during chemical mechanical planarization of copper in acetic acid and dodecyl sulfate solutions  

Microsoft Academic Search

Electrochemical impedance spectroscopy (EIS) is employed to study the competitive reactions of surface corrosion and passivating film formation on a Cu-rotating disc electrode (RDE) in pH-adjusted solutions of H2O2, acetic acid (HAc) and ammonium dodecyl sulfate (ADS). The surface reactions that occur at the open circuit potential of this system are relevant for chemical mechanical planarization (CMP) of Cu-interconnect structures.

J. P. Zheng; D. Roy

2009-01-01

132

Fabrication and characterization of p-type ZnO films by pyrolysis of zinc-acetate–ammonia solution  

Microsoft Academic Search

P-type zinc oxide films were prepared on glass substrates by pyrolysis of ultrasonically nebulized zinc-acetate–ammonia solution. UV–visible absorption spectra, X-ray diffraction, and Hall effect measurements were carried out. Results show that zinc oxide films prepared by this method are preferentially oriented with the c-axis perpendicular to the substrate surface. The results of Hall effect measurements show that p-type conducting ZnO

Zhenguo Ji; Chengxin Yang; Kun Liu; Zhizhen Ye

2003-01-01

133

Ion association and solvation behavior of some alkali metal acetates in aqueous 2-butanol solutions at T = 298.15, 303.15 and 308.15 K  

Microsoft Academic Search

Molar conductance of lithium acetate, sodium acetate and potassium acetate were studied in aqueous 2-butanol solutions with an alcohol mass fraction (w2) of 0.70, 0.80 and 0.90 at 298.15, 303.15 and 308.15K. The conductance data were analyzed with the Fuoss conductance–concentration equation to evaluate the limiting molar conductances (?0), association constants (KA,c) and cosphere diameter (R) for ion-pair formation. Gibbs

Radhey Shyam Sah; Biswajit Sinha; Mahendra Nath Roy

2011-01-01

134

Amidolytic, Procoagulant, and Activation-Suppressing Proteins Produced by Contact Activation of Blood Factor XII in Buffer Solution  

PubMed Central

The relative proportions of enzymes with amidolytic or procoagulant activity produced by contact activation of the blood zymogen factor XII (FXII, Hageman factor) in buffer solution depends on activator surface chemistry/energy. As a consequence, chromogenic assay of amidolytic activity (cleavage of amino acid bonds in s-2302 chromogen) does not correlate with the traditional plasma-coagulation-time assay for procoagulant activity (protease activity inducing clotting of blood plasma). Amidolytic activity did not vary significantly with activator-particle surface energy, herein measured as water adhesion tension ?°=?lv°cos?a; where ?lv° is pure buffer interfacial tension and ?a is the advancing contact angle. By contrast, procoagulant activity varied as a parabolic-like function of ?o, high at both hydrophobic and hydrophilic extremes of activator surface energy and falling through a broad minimum within a 20

Golas, Avantika; Yeh, Chyi-Huey Joshua; Siedlecki, Christopher A.; Vogler, Erwin A.

2011-01-01

135

Preparation of DNA films for studies under vacuum conditions. The influence of cations in buffer solutions  

NASA Astrophysics Data System (ADS)

Experiments were carried out to determine the optimum conditions required for the preparation of uniform films of supercoiled plasmid DNA to be used in irradiation experiments under high vacuum conditions. Investigations reveal that significant damage to the DNA molecules occurs due to the evacuation process when films were formed from DNA samples in ultra high purity water only. A variety of bases were tested for their possible protective capabilities and sodium hydroxide solution was found to be the most effective in maintaining the supercoiled structure of plasmid DNA during the preparation process. Using a transmission electron microscope we also examined the structure of the DNA films which are formed upon evacuation and how the proposed adducts influence the preparation process. It was found that the addition of bases cause the DNA to aggregate, noting that a base is required for the stability of the DNA molecules. The experimental results presented in this paper show that it may not be possible to perform experiments on so-called pure DNA under vacuum with no stabilizers being added to the sample before the evacuation process.

?mia?ek, M. A.; Balog, R.; Jones, N. C.; Field, D.; Mason, N. J.

2010-10-01

136

Ozonation of trichloroethylene in acetic acid solution with soluble and solid humic acid  

Microsoft Academic Search

The combined flushing and oxidation process using acetic acid and ozone has been used successfully to remove trichloroethylene (TCE) completely from contaminated soil. In this study, the effects of humic acid, a fraction of the organic matter in soil, over the performance of TCE decomposition was evaluated. TCE decomposition by ozone was enhanced by the presence of humic acid at

Martha E. Alcántara-Garduño; Tetsuji Okuda; Wataru Nishijima; Mitsumasa Okada

2008-01-01

137

Salt Effects on Solvolysis Reactions of p-Nitrophenyl Alkanoates Catalyzed by 4-(Dialkylamino) pyridine-Functionalized Polymer in Buffered Water and Aqueous Methanol Solutions.  

National Technical Information Service (NTIS)

Specific salting-in effects that lead to striking substrate selectivity were observed for the hydrolysis of p-nitrophenyl alkanoates 2 (n=2-16) catalyzed by 4-(dialkylamino) pyridine-functionalized polymer 1 in aqueous Tris buffer solution at pH 8.0 and 3...

G. J. Wang D. Ye W. K. Fife

1996-01-01

138

Acid neutralizing processes in an alpine watershed front range, Colorado, U.S.A.-1: Buffering capacity of dissolved organic carbon in soil solutions  

USGS Publications Warehouse

Soil interstitial waters in the Green Lakes Valley, Front Range, Colorado were studied to evaluate the capacity of the soil system to buffer acid deposition. In order to determine the contribution of humic substances to the buffering capacity of a given soil, dissolved organic carbon (DOC) and pH of the soil solutions were measured. The concentration of the organic anion, Ai-, derived from DOC at sample pH and the concentration of organic anion, Ax- at the equivalence point were calculated using carboxyl contents from isolated and purified humic material from soil solutions. Subtracting Ax- from Ai- yields the contribution of humic substances to the buffering capacity (Aequiv.-). Using this method, one can evaluate the relative contribution of inorganic and organic constituents to the acid neutralizing capacity (ANC) of the soil solutions. The relative contribution of organic acids to the overall ANC was found to be extremely important in the alpine wetland (52%) and the forest-tundra ecotone (40%), and somewhat less important in the alpine tundra sites (20%). A failure to recognize the importance of organic acids in soil solutions to the ANC will result in erroneous estimates of the buffering capacity in the alpine environment of the Front Range, Colorado. ?? 1988.

Iggy, Litaor, M.; Thurman, E. M.

1988-01-01

139

Assignment of reference pH-values to primary standard buffer solutions for standardization of potentiometric sensors in acetonitrile-water mixtures  

Microsoft Academic Search

Standard pH-values pHPS for seven primary standard buffer solutions in 0, 10, 30, 40, 50, 70 and 100% (w\\/w) acetonitrile-water mixed solvents at 298.15 K were determined according to the criteria recently endorsed by IUPAC. The preferential solvation of the ions in acetonitrile-water mixtures was studied in order to clarify the acid-base behaviour of the solutes in such mixtures. The

José Barbosa; Victoria Sanz-Nebot

1995-01-01

140

The bacteriophage phi29 head-tail connector imaged at high resolution with the atomic force microscope in buffer solution.  

PubMed Central

The surfaces of two- and three-dimensional phi29 connector crystals were imaged in buffer solution by atomic force microscopy (AFM). Both topographies show a rectangular unit cell with dimensions of 16.5 nm x 16.5 nm. High resolution images of connectors from the two-dimensional crystal surface show two connectors per unit cell confirming the p42(1)2 symmetry. The height of the connector was estimated to be at least 7.6 nm, a value close to that found in previous studies using different techniques. The 12 subunits of the wide connector domain were clearly resolved and showed a right-handed vorticity. The channel running along the connector had a diameter of 3.7 nm in the wide domain, while it was 1.7 nm in the narrow domain end, thus suggesting a tronco-conical channel shape. Moreover, the narrow connector end appears to be rather flexible. When the force applied to the stylus was between 50 and 100 pN, the connector end was fully extended. At forces of approximately 150 pN, these ends were pushed towards the crystal surface. The complementation of the AFM data with the three-dimensional reconstruction obtained from electron microscopy not only confirmed the model proposed, but also offers new insights that may help to explain the role of the connector in DNA packing.

Muller, D J; Engel, A; Carrascosa, J L; Velez, M

1997-01-01

141

Thermodynamical characteristics of the reaction of pyridoxal-5'-phosphate with L-amino acids in aqueous buffer solution  

NASA Astrophysics Data System (ADS)

The reaction of pyridoxal-5'-phosphate with L-isomers of alanine, lysine, arginine, aspartic acid, glutamic acid, and glycine in phosphate buffer solution was studied by absorption spectroscopy and the calorimetry of dissolution at physiological acidity of the medium (pH 7.35). The formation constants of Schiff bases during reactions and changes in Gibbs energy, enthalpy, and entropy were determined. It was shown that the formation constant of the Schiff base and its spectral properties depend on the nature of the bound amino acid. The progress of the reaction with a majority of amino acids is governed by the entropy factor due to the predominant role of the dehydration effect of the reaction center of amino acids during chemical reactions. The intramolecular electrostatic interaction of an ionized phosphate group with the positively charged amino group on the end of the chain of amino acid residue stabilizes the Schiff bases formed by lysine and arginine. The extinction coefficient of the base, equilibrium constant, and the exothermic effect of the reaction then increase. The excess negative charge on the end of the chain of amino acid residues of aspartic and glutamic acids destabilizes the molecule of the Schiff base. In this case, the equilibrium constant decreases and the endothermic effect of the reaction increases.

Barannikov, V. P.; Badelin, V. G.; Venediktov, E. A.; Mezhevoi, I. N.; Guseinov, S. S.

2011-01-01

142

The Partial Pressures of Formic and Acetic Acids above Some Aqueous Solutions; and Their Partial Molal Free Energies at 1.0 Molal Concentration  

Microsoft Academic Search

The paucity of data pertaining to the vapor pressures of aqueous solutions of the organic acids has hitherto retarded thermodynamic calculations in this field. In the present study the partial pressures of formic acid above three of its solutions and those of acetic acid above two solutions have been measured at 25°C. From these results the partial molal free energies

Wm. A. Kaye; George S. Parks

1934-01-01

143

Changes in the structure of water in aqueous solutions of acetic acid, depending on concentration and temperature according to densitometry, viscosimetry, and IR spectroscopy data  

NASA Astrophysics Data System (ADS)

The structural features of aqueous solutions of acetic acid are studied by means of viscosimetry, densimetry, and IR spectroscopy within the temperature range of 283.15-333.15 K and a concentration range of 0-80%. The results from our experiments are used to calculate the parameters of viscous flow activation, the structural temperature, the partial molar volume of acetic acid in the solution, the thermal expansion coefficient, and the energies and lengths of the hydrogen bonds between water molecules. The concentration dependences of these parameters are analyzed. Based on the obtained results, we conclude that acetic acid disrupts the structure of water.

Masimov, E. A.; Khasanov, G. Sh.; Pashaev, B. G.

2013-06-01

144

Vapour pressure measurements and thermodynamic properties of aqueous solutions of sodium acetate  

Microsoft Academic Search

The vapour pressure of (sodium acetate + water) was measured in the temperature range 278.15 K to 308.15 K and in the molality range 0.65 mol · kg?1to 6.47 mol · kg?1with a static method. Water activities and osmotic coefficients were calculated. A comprehensive search of the available literature for the relevant thermodynamic data of the investigated system was carried

Roland Beyer; Michael Steiger

2002-01-01

145

THE SEPARATION OF CERIUM FROM THE TRIVALENT RARE EARTHS USING HYDROGEN PEROXIDE AND SODIUM ACETATE  

Microsoft Academic Search

Cerium was completely precipitated (>99%) as a cerium(IV) peroxyacetate ; from a nitrate solution containing cerium, yttrium, and other trivalent rare ; earths with only 5 to 15% of the trivalent rare earths carrying on the cerium ; precipitate. The process is accomplished by the addition of a buffered hydrogen ; peroxide-sodium acetate solution to the rare earth nitrate feed

E. J. Wheelwright; N. C. Howard

1960-01-01

146

Synthesis and Spectroscopic Analysis of a Cyclic Acetal: A Dehydration Performed in Aqueous Solution  

NASA Astrophysics Data System (ADS)

The treatment of aldehydes (and ketones) with diols in the presence of acid gives acetals (and ketals) in an equilibrium reaction. Treatment of pentaerythritol with benzaldehyde in aqueous acid gives the monoacetal, 5,5-bis(hydroxymethyl)-2-phenyl-1,3-dioxane. The reaction has a number of interesting features. The isolated product is the monobenzal not the dibenzal, and the reaction, a dehydration, is performed in water. The reaction proceeds to provide the acetal owing to the insolubility of the product in the aqueous reaction medium, thus removing the product from the equilibrium. This experiment is suitable for incorporation into the undergraduate organic laboratory as the synthesis of a product for characterization by melting point, solubility, and proton nuclear magnetic resonance. Only through recognition of the three-dimensional structure of the dioxane ring can students explain the appearance of the 1H NMR spectrum of the product. The hydroxymethyl groups of the product are inequivalent, as are the hydrogens of the methylenes in the ring. The experiment may also be presented as a group exercise to optimize the conditions of a reaction to maximize the yield of the desired product.

Collard, David M.; Jones, Adolphus G.; Kriegel, Robert M.

2001-01-01

147

Nanofiltration of rhodium tris(triphenylphosphine) catalyst in ethyl acetate solution  

NASA Astrophysics Data System (ADS)

Solvent resistant nanofiltration (SRNF) using polymer membranes has recently received enhanced attention due to the search for cleaner and more energy-efficient technologies. The large size of the rhodium tris(triphenylphosphine) [HRh(CO)(PPh3)3] catalyst (>400 Da) - relative to other components of the hydroformylation reaction provides the opportunity for a membrane separation based on retention of the catalyst species while permeating the solvent. The compatibility of the solvent-polyimide membrane (DuraMem{trade mark, serif} 200 and DuraMem{trade mark, serif} 500) combinations was assessed in terms of the membrane stability in solvent plus non-zero solvent flux at 2.0 MPa. Good HRh(CO)(PPh3)3 rejection (>0.95) and solvent fluxes of 9.9 L/m2.h1 at 2.0 MPa were obtained in the catalyst-ethyl acetate-DuraMem 500 system. The effect of pressure and catalyst concentration on the solvent flux and catalyst rejection was conducted on the catalyst-ethyl acetate-membrane systems. Increasing pressure substantially improved both solvent flux and catalyst rejection, while increasing catalyst concentration was found to be beneficial in terms of substantial increases in catalyst rejection without significantly affecting solvent flux.

Shaharun, Maizatul S.; Mustafa, Ahmad K.; Taha, Mohd F.

2012-09-01

148

Use of aqueous solutions of sodium alginate and calcium acetate as quenching liquids  

Microsoft Academic Search

Aqueous solutions of SA are prepared from a film of it obtained from an algal extract. The algai extract is prepared from seaweed of the species Lc~inaria saccharina and digitata. For the quenching solution 1--3% of the dried seaweeds is infused for 3--5 days in a 1% aqueous sodium carbonate solution. To obtain the SA film sulfuric or hydrochloric acid

M. G. Kurmashov

1982-01-01

149

Synthesis of Titania Pillared Saponite in Aqueous Solution of Acetic Acid  

Microsoft Academic Search

The preparation of TiO2-pillared saponite was carried out in a CH3COOH aqueous solution. Titanium ion species to intercalate into the interlayer of saponite were obtained by an addition of Ti(C3H7O)4 to an aqueous solution of CH3COOH and by subsequent aging of the solution for a prescribed time. Ti4+-intercalated saponite including organic materials was obtained by ion exchange. After the sample

Y. Kitayama; T. Kodama; M. Abe; H. Shimotsuma; Y. Matsuda

1998-01-01

150

Michrochip chromatography using an open-tubular microchannel and a ternary water-ACN-ethyl acetate mixture carrier solution.  

PubMed

A capillary chromatography system has been developed using a ternary mixed-solvents solution, i.e. water-hydrophilic/hydrophobic organic solvent mixture as a carrier solution. Here, we tried to carry out the chromatographic system on a microchip incorporating the open-tubular microchannels. A model analyte solution of isoluminol isothiocyanate (ILITC) and ILITC-labeled biomolecule was injected to the double T-junction part on the microchip. The analyte solution was delivered in the separation microchannel (40 ?m deep, 100 ?m wide, and 22 cm long) with the ternary water-ACN-ethyl acetate mixture carrier solution (3:8:4 volume ratio, the organic solvent rich or 15:3:2 volume ratio, the water-rich). The analyte, free-ILITC and labeled BSA mixture, was separated through the microchannel, where the carrier solvents were radially distributed in the separation channel generating inner and outer phases. The outer phase acts as a pseudo-stationary phase under laminar flow conditions in the system. The ILITC and the labeled BSA were eluted and detected with chemiluminescence reaction. PMID:23378128

Matsuda, Takafumi; Yamashita, Kenichi; Maeda, Hideaki; Hashimoto, Masahiko; Tsukagoshi, Kazuhiko

2013-02-04

151

Protein-Water and Protein-Buffer Interactions in the Aqueous Solution of an Intrinsically Unstructured Plant Dehydrin: NMR Intensity and DSC Aspects  

PubMed Central

Proton NMR intensity and differential scanning calorimetry measurements were carried out on an intrinsically unstructured late embryogenesis abundant protein, ERD10, the globular BSA, and various buffer solutions to characterize water and ion binding of proteins by this novel combination of experimental approaches. By quantifying the number of hydration water molecules, the results demonstrate the interaction between the protein and NaCl and between buffer and NaCl on a microscopic level. The findings overall provide direct evidence that the intrinsically unstructured ERD10 not only has a high hydration capacity but can also bind a large amount of charged solute ions. In accord, the dehydration stress function of this protein probably results from its simultaneous action of retaining water in the drying cells and preventing an adverse increase in ionic strength, thus countering deleterious effects such as protein denaturation.

Tompa, P.; Banki, P.; Bokor, M.; Kamasa, P.; Kovacs, D.; Lasanda, G.; Tompa, K.

2006-01-01

152

Kinetics and Mechanism of Aminolysis of Phenyl Acetates in Aqueous Solutions of Poly(ethylenimine).  

PubMed

Second-order rate constants (k(n)) for the aminolysis of some phenyl acetates with poly(ethylenimine) (PEI) were obtained in a pH range 4.36-11.20 at 25 degrees C in 1 M KCl. Linear Bronsted-type plots (log k(n) vs pK(N) of PEI) were found for less reactive esters 2-nitrophenyl acetate, 4-acetoxy-3-chlorobenzoic acid, and 4-acetoxybenzenesulfonate with slopes of 0.92, 0.99, and 0.82, respectively. Curved plots were obtained for 3-acetoxy-2,6-dinitrobenzoic acid and 4-acetoxy-3-nitrobenzenesulfonate, which are consistent with a stepwise reaction. The most likely mechanism involves the existence of a tetrahedral intermediate (T(+/-)) and a change in the rate-determining step from its breakdown to its formation when the basicity of the polyamine increases. A semiempirical equation was used to calculate the values of limiting slopes of the plots (0.9 and 0.1 for both esters) and pK(N) at the center of the curvature of the plots (pK(N degrees ) = 7.94 and 9.02, respectively). The values of pK(N degrees ) are lower than those estimated for the aminolysis of the same esters with simple monomeric amines (pK(n degrees ) > 11) because of a better leaving ability of the aryl oxide ion from the tetrahedral intermediate when amino groups of PEI instead of simple amines are involved. Estimation of the pK's of the reactive intermediates and of the microscopic rate constants for the proton transfer from T(+/-) to PEI or from PEIH(+) to T(+/-) indicates that either base or acid catalysis is unimportant in the aminolysis of these esters by PEI. PMID:11667037

Arcelli, Antonio; Concilio, Carlo

1996-03-01

153

Detailed investigations on La 2Zr 2O 7 buffer layers for YBCO-coated conductors prepared by chemical solution deposition  

Microsoft Academic Search

An extensive study of the growth and properties of La2Zr2O7 (LZO) buffer layers prepared by chemical solution deposition on Ni–5at.%W rolling-assisted biaxially textured substrates, which is presently of great interest for the preparation of YBa2Cu3O7?x-coated conductors, is presented. The main focus was on the understanding of the decomposition of the precursor layers, and their growth and texture formation, as well

K. Knoth; R. Hühne; S. Oswald; L. Schultz; B. Holzapfel

2007-01-01

154

Equations for calculation of the pH of buffer solutions containing sodium or potassium dihydrogen phosphate, sodium hydrogen phosphate, and sodium chloride at 25°C  

Microsoft Academic Search

Published thermodynamic data measured in aqueous mixtures of sodium or potassium dihydrogen phosphate with hydrogen phosphate\\u000a and chloride at 25°C were used to test recently developed methods for calculation of the pH of phosphate buffer solutions.\\u000a Equations for ionic activity coefficients are used in these methods. It is shown that all data used in the tests up to an\\u000a ionic

Jaakko I. Partanen; Pentti O. Minkkinen

1997-01-01

155

Wire segmenting for improved buffer insertion  

Microsoft Academic Search

Buffer insertion seeks to place buffers on the wires of a signal netto minimize delay. Van Ginneken [Buffer Placement in Distributed RC-tree Networks for Minimal Elmore Delay] proposed an optimal dynamicprogramming solution (with extensions proposed by [7] [8][9] [12]) such that at most one buffer can be placed on a singlewire. This constraint can hurt solution quality, but it may

Charles J. Alpert; Anirudh Devgan

1997-01-01

156

Plasma acetate, gluconate and interleukin-6 profiles during and after cardiopulmonary bypass: a comparison of Plasma-Lyte 148 with a bicarbonate-balanced solution  

PubMed Central

Introduction As even small concentrations of acetate in the plasma result in pro-inflammatory and cardiotoxic effects, it has been removed from renal replacement fluids. However, Plasma-Lyte 148 (Plasma-Lyte), an electrolyte replacement solution containing acetate plus gluconate is a common circuit prime for cardio-pulmonary bypass (CPB). No published data exist on the peak plasma acetate and gluconate concentrations resulting from the use of Plasma-Lyte 148 during CPB. Methods Thirty adult patients were systematically allocated 1:1 to CPB prime with either bicarbonate-balanced fluid (24 mmol/L bicarbonate) or Plasma-Lyte 148. Arterial blood acetate, gluconate and interleukin-6 (IL-6) levels were measured immediately before CPB (T1), three minutes after CPB commencement (T2), immediately before CPB separation (T3), and four hours post separation (T4). Results Acetate concentrations (normal 0.04 to 0.07 mmol/L) became markedly elevated at T2, where the Plasma-Lyte group (median 3.69, range (2.46 to 8.55)) exceeded the bicarbonate group (0.16 (0.02 to 3.49), P < 0.0005). At T3, levels had declined but the differential pattern remained apparent (Plasma-Lyte 0.35 (0.00 to 1.84) versus bicarbonate 0.17 (0.00 to 0.81)). Normal circulating acetate concentrations were not restored until T4. Similar gluconate concentration profiles and inter-group differences were seen, with a slower T3 decay. IL-6 increased across CPB, peaking at T4, with no clear difference between groups. Conclusions Use of acetate containing prime solutions result in supraphysiological plasma concentrations of acetate. The use of acetate-free prime fluid in CPB significantly reduced but did not eliminate large acetate surges in cardiac surgical patients. Complete elimination of acetate surges would require the use of acetate free bolus fluids and cardioplegia solutions. Trial registration Australia and New Zealand Clinical Trials Register (ANZCTR): ACTRN12610000267055

2011-01-01

157

Influence of different buffer solutions on the performance of anodic Pt-Ru\\/C nanoparticle electrocatalysts for a direct methanol fuel cell  

Microsoft Academic Search

This research aims to improve the activity of Pt-Ru nanoparticle electrocatalysts and thus, to lower the catalyst loading in anodes for methanol electrooxidation. The direct methanol fuel cell (DMFC) anodic Pt-Ru\\/C nanoparticle electrocatalysts were prepared using a chemical reduction method. The pH values of the reductive solutions were adjusted by different buffer solutions of CH3COONa–NaOH, C6H5Na3O7–NaOH, and Na2CO3–NaHCO3, respectively. The

Zhen-Bo Wang; Ge-Ping Yin; Peng-Fei Shi; Bo-Qian Yang; Peter-Xian Feng

2007-01-01

158

Inhibitory effect of hydroxypropyl methylcellulose acetate succinate on drug recrystallization from a supersaturated solution assessed using nuclear magnetic resonance measurements.  

PubMed

We examined the inhibitory effect of hydroxypropyl methylcellulose acetate succinate (HPMC-AS) on drug recrystallization from a supersaturated solution using carbamazepine (CBZ) and phenytoin (PHT) as model drugs. HPMC-AS HF grade (HF) inhibited the recrystallization of CBZ more strongly than that by HPMC-AS LF grade (LF). 1D-(1)H NMR measurements showed that the molecular mobility of CBZ was clearly suppressed in the HF solution compared to that in the LF solution. Interaction between CBZ and HF in a supersaturated solution was directly detected using nuclear Overhauser effect spectroscopy (NOESY). The cross-peak intensity obtained using NOESY of HF protons with CBZ aromatic protons was greater than that with the amide proton, which indicated that CBZ had hydrophobic interactions with HF in a supersaturated solution. In contrast, no interaction was observed between CBZ and LF in the LF solution. Saturation transfer difference NMR measurement was used to determine the interaction sites between CBZ and HF. Strong interaction with CBZ was observed with the acetyl substituent of HPMC-AS although the interaction with the succinoyl substituent was quite small. The acetyl groups played an important role in the hydrophobic interaction between HF and CBZ. In addition, HF appeared to be more hydrophobic than LF because of the smaller ratio of the succinoyl substituent. This might be responsible for the strong hydrophobic interaction between HF and CBZ. The intermolecular interactions between CBZ and HPMC-AS shown by using NMR spectroscopy clearly explained the strength of inhibition of HPMC-AS on drug recrystallization. PMID:24025080

Ueda, Keisuke; Higashi, Kenjirou; Yamamoto, Keiji; Moribe, Kunikazu

2013-09-26

159

Effect of Time and Degree of Saturation of Buffer Solutions on Artificial Carious Lesion Formation in Human Tooth Enamel  

Microsoft Academic Search

The chemical systems to produce carious lesions described in the literature can be divided into three types: (a) gel systems, (b) systems containing a substance which decreases the dissolution rate of the mineral in the surface area of tooth enamel and (c) buffer systems containing calcium and phosphate. The third system can give essential information in the physicochemical sense, if

H. M. Theuns; J. W. E. van Dijk; F. C. M. Driessens; A. Groeneveld

1983-01-01

160

Experimental determination of portlandite solubility in H sub 2 O and acetate solutions at 100-350C and 500 bars: Constraints on calcium hydroxide and calcium acetate complex stability  

SciTech Connect

The solubility of portlandite was measured in H{sub 2}O and aqueous acetate solutions of varying concentration (1-10 mmolal) at temperatures from 100-350C and 500 bars pressure. Dissolved Ca concentrations increased with decreasing temperature and increasing dissolved acetate concentration. Using known thermodynamic data for portlandite, H{sup +}, OH{sup {minus}}, Ca{sup ++}, CH{sub 3}COO{sup {minus}}, CH{sub 3}COOH{sup 0}, and H{sub 2}O{sub (1)}, stability constants for CaOH{sup +} and CaCH{sub 3}COO{sup +} complexes were determined. These results indicate that the stabilities of CaOH{sup 1} and CaCH{sub 3}COO{sup 1} complex increase with increasing temperature. In the acetate-free experiments, CaOH{sup +} is the dominant form of dissolved Ca in equilibrium with portlandite at 100-350C and 500 bars, while in the acetate-rich experiments (10 mmolal acetate), Ca{sup ++} and CaOH{sup +} are the dominant forms of Ca in equilibrium with portlandite at low temperature (100-200C) and CaCH{sub 3}COO{sup +} and CaOH{sup +} are the dominant forms at relatively high temperature (200-350C). Metal-acetate complexing has long been suggested as an important mechanism for mobilizing base metals during the formation of ore deposits in organic-rich environments. Due to the stability of CaCH{sub 3}COO{sup +} complex in Ca-bearing fluids at elevated temperatures and pressures, however, the effectiveness of dissolved acetate to enhance base metal sulfide solubility is limited.

Seewald, J.S.; Seyfried, W.E. Jr. (Univ. of Minnesota, Minneapolis (United States))

1991-03-01

161

TES buffer-induced phase separation of aqueous solutions of several water-miscible organic solvents at 298.15 K: phase diagrams and molecular dynamic simulations.  

PubMed

Water and the organic solvents tetrahydrofuran, 1,3-dioxolane, 1,4-dioxane, 1-propanol, 2-propanol, tert-butanol, acetonitrile, or acetone are completely miscible in all proportions at room temperature. Here, we present new buffering-out phase separation systems that the above mentioned organic aqueous solutions can be induced to form two liquid phases in the presence of a biological buffer 2-[[1,3-dihydroxy-2-(hydroxymethyl)propan-2-yl]amino]ethanesulfonic acid (TES). The lower liquid phase is rich in water and buffer, and the upper phase is organic rich. This observation has both practical and mechanistic interests. The phase diagrams of these systems were constructed by experimental measurements at ambient conditions. Molecular dynamic (MD) simulations were performed for TES + water + THF system to understand the interactions between TES, water, and organic solvent at molecular level. Several composition-sets for this system, beyond and inside the liquid-liquid phase-splitting region, have been simulated. Interestingly, the MD simulation for compositions inside the phase separation region showed that THF molecules are forced out from the water network to start forming a new liquid phase. The hydrogen-bonds, hydrogen-bonds lifetimes, hydrogen-bond energies, radial distribution functions, coordination numbers, the electrostatic interactions, and the van der Waals interactions between the different pairs have been calculated. Additionally, MD simulations for TES + water + tert-butanol?acetonitrile?acetone phase separation systems were simulated. The results from MD simulations provide an explanation for the buffering-out phenomena observed in [TES + water + organic solvent] systems by a mechanism controlled by the competitive interactions of the buffer and the organic solvent with water. The molecular mechanism reported here is helpful for designing new benign separation materials. PMID:23822250

Taha, Mohamed; Lee, Ming-Jer

2013-06-28

162

TES buffer-induced phase separation of aqueous solutions of several water-miscible organic solvents at 298.15 K: Phase diagrams and molecular dynamic simulations  

NASA Astrophysics Data System (ADS)

Water and the organic solvents tetrahydrofuran, 1,3-dioxolane, 1,4-dioxane, 1-propanol, 2-propanol, tert-butanol, acetonitrile, or acetone are completely miscible in all proportions at room temperature. Here, we present new buffering-out phase separation systems that the above mentioned organic aqueous solutions can be induced to form two liquid phases in the presence of a biological buffer 2-[[1,3-dihydroxy-2-(hydroxymethyl)propan-2-yl]amino]ethanesulfonic acid (TES). The lower liquid phase is rich in water and buffer, and the upper phase is organic rich. This observation has both practical and mechanistic interests. The phase diagrams of these systems were constructed by experimental measurements at ambient conditions. Molecular dynamic (MD) simulations were performed for TES + water + THF system to understand the interactions between TES, water, and organic solvent at molecular level. Several composition-sets for this system, beyond and inside the liquid-liquid phase-splitting region, have been simulated. Interestingly, the MD simulation for compositions inside the phase separation region showed that THF molecules are forced out from the water network to start forming a new liquid phase. The hydrogen-bonds, hydrogen-bonds lifetimes, hydrogen-bond energies, radial distribution functions, coordination numbers, the electrostatic interactions, and the van der Waals interactions between the different pairs have been calculated. Additionally, MD simulations for TES + water + tert-butanol/acetonitrile/acetone phase separation systems were simulated. The results from MD simulations provide an explanation for the buffering-out phenomena observed in [TES + water + organic solvent] systems by a mechanism controlled by the competitive interactions of the buffer and the organic solvent with water. The molecular mechanism reported here is helpful for designing new benign separation materials.

Taha, Mohamed; Lee, Ming-Jer

2013-06-01

163

Resonance Raman characterization of different forms of ground-state 8-bromo-7-hydroxyquinoline caged acetate in aqueous solutions.  

PubMed

The 8-bromo-7-hydroxyquinolinyl group (BHQ) is a derivative of 7-hydroxyquinoline (7-HQ) and BHQ molecules coexisting as different forms in aqueous solution. Absorption and resonance Raman spectroscopic methods were used to examine 8-bromo-7-hydroxyquinoline protected acetate (BHQ-OAc) in acetonitrile (MeCN), H(2)O/MeCN (60:40, v/v, pH 6 approximately 7), and NaOH-H(2)O/MeCN (60:40, v/v, pH 11 approximately 12) to obtain a better characterization of the forms of the ground-state species of BHQ-OAc in aqueous solutions and to examine their properties. The absorption spectra of BHQ-OAc in water show no absorption bands of the tautomeric species unlike the strong band at about 400 nm observed for the tautomeric form in 7-HQ aqueous solution. The resonance Raman spectra in conjunction with Raman spectra predicted from density functional theory (DFT) calculations reveal the observation of a double Raman band system characteristic of the neutral form (the nominal C=C ring stretching, C-N stretching, and O-H bending modes at 1564 and 1607 cm(-1)) and a single Raman band diagnostic of the enol-deprotonated anionic form (the nominal C=C ring, C-N, and C-O(-) stretching modes in the 1593 cm(-1) region). These results suggest that the neutral form of BHQ-OAc is the major species in neutral aqueous solution. There is a modest increase in the amount of the anionic form and a big decrease in the amount of the tautomeric form of the molecules for BHQ-OAc compared to 7-HQ in neutral aqueous solution. The presence of the 8-bromo group and/or competitive hydrogen bonding that hinder the formation and transfer process of a BHQ-OAc-water cyclic complex may be responsible for this large substituent effect. PMID:19296708

An, Hui-Ying; Ma, Chensheng; Nganga, Jameil L; Zhu, Yue; Dore, Timothy M; Phillips, David Lee

2009-03-26

164

Circuit solutions on ESD protection design for mixed-voltage I\\/O buffers in nanoscale CMOS  

Microsoft Academic Search

Electrostatic discharge (ESD) protection for mixed-voltage I\\/O interfaces has been one of the major challenges of system-on-a-chip (SOC) implementation in nanoscale CMOS processes. Moreover, the gate leakage current across thin gate-oxide devices has serious degradation on circuit performance while circuits implementing in nanoscale CMOS processes. The on-chip ESD protection circuit for mixed-voltage I\\/O buffers should meet the gate-oxide reliability constraints

Ming-Dou Ker; Chang-Tzu Wang

2009-01-01

165

Complexation of buffer constituents with neutral complexation agents: part I. Impact on common buffer properties.  

PubMed

The complexation of buffer constituents with the complexation agent present in the solution can very significantly influence the buffer properties, such as pH, ionic strength, or conductivity. These parameters are often crucial for selection of the separation conditions in capillary electrophoresis or high-pressure liquid chromatography (HPLC) and can significantly affect results of separation, particularly for capillary electrophoresis as shown in Part II of this paper series ( Beneš, M.; Riesová, M.; Svobodová, J.; Tesa?ová, E.; Dubský, P.; Gaš, B. Anal. Chem. 2013 , DOI: 10.1021/ac401381d ). In this paper, the impact of complexation of buffer constituents with a neutral complexation agent is demonstrated theoretically as well as experimentally for the model buffer system composed of benzoic acid/LiOH or common buffers (e.g., CHES/LiOH, TAPS/LiOH, Tricine/LiOH, MOPS/LiOH, MES/LiOH, and acetic acid/LiOH). Cyclodextrins as common chiral selectors were used as model complexation agents. We were not only able to demonstrate substantial changes of pH but also to predict the general complexation characteristics of selected compounds. Because of the zwitterion character of the common buffer constituents, their charged forms complex stronger with cyclodextrins than the neutral ones do. This was fully proven by NMR measurements. Additionally complexation constants of both forms of selected compounds were determined by NMR and affinity capillary electrophoresis with a very good agreement of obtained values. These data were advantageously used for the theoretical descriptions of variations in pH, depending on the composition and concentration of the buffer. Theoretical predictions were shown to be a useful tool for deriving some general rules and laws for complexing systems. PMID:23889602

Riesová, Martina; Svobodová, Jana; Tošner, Zden?k; Beneš, Martin; Tesa?ová, Eva; Gaš, Bohuslav

2013-08-29

166

Electrochemical behaviour of technetium in acetic buffer  

NASA Astrophysics Data System (ADS)

In order to understand the complex reduction mechanism of pertechnetate ions on mercury electrode we have developed electrochemical techniques which use an additional time parameter to the classical methods applied on mercury microelectrode: 3 Dimensional polarography and 3D differential capacity measurements have been investigated in addition with coulometry, cyclic voltammetry, and radioactivity determinations. We have concluded that the first VII?III reduction wave, which have been described in literature, has to be associated with the successive VII?V reactions followed by the disproportion of Tc(V) and formation of Tc(VI) and insoluble tetravalent species which are adsorbed on the electrode and reduced to trivalent ions. Then, reduction of Tc(III) to Tc(0) is reached through Tc(II) and Tc(I) intermediate species. The intermediates are characterised depending on the time window of observation.

Courson, O.; Le Naour, C.; David, F.; Bolyos, A.; Maslennikov, A.; Papadopoulos, N.

1999-01-01

167

YBa2Cu3Ox Thin Films with Yttria Stabilized Zirconia Buffer Layer on Metal Substrate by Liquid Source Chemical Vapor Deposition Using Tetrahydrofuran Solution of ?-Diketonates  

NASA Astrophysics Data System (ADS)

Textured YBa2Cu3O x (YBCO) thin films with c-axis orientation on Ni-based metal substrate with yttria stabilized zirconia (YSZ) and Pt buffer layers were formed by liquid source chemical vapor deposition (LS-CVD) using tetrahydrofuran (THF) solution of ?-diketonates. The YSZ buffer layer with a-axis orientation was formed by the similar LS-CVD on prebuffer layers of amorphous YSZ and Pt deposited by sputtering at room temperature. The CVD-YSZ buffer layer was mechanically polished before the deposition of YBCO. By transmission electron microscopy (TEM) and analytical electron microscopy (AEM), it was ascertained that YBCO and YSZ layers had platelike and column-shaped grains, respectively. An intermetallic compound of the Pt-Ni-Cr system was produced in the vicinity between the YSZ layer and metal substrate. The critical temperature (T c) of 91 K and the transport critical current densities (J c) of 1.4×105 A/cm2 at 77 K, zero field, and 2.0×104 A/cm2 at 1.5 T were achieved.

Matsuno, Shigeru; Umemura, Toshio; Uchikawa, Fusaoki; Ikeda, Bunko

1995-05-01

168

Solid phase extraction of proteins from buffer solutions employing capillary-channeled polymer (C-CP) fibers as the stationary phase.  

PubMed

Polypropylene (PP) capillary-channeled polymer (C-CP) fibers are applied for solid phase extraction (SPE) of proteins from aqueous buffer solutions using a micropipette tip-based format. A process was developed in which centrifugation is used as the moving force for solution passage in the loading/washing steps instead of the previously employed manual aspiration. The complete procedure requires ~15 minutes, with the number of samples run in parallel limited only by the capacity of the centrifuge. The method performance was evaluated based on adsorption and elution characteristics of several proteins (cytochrome c, lysozyme, myoglobin, and glucose oxidase) from 150 mM phosphate buffered saline (PBS) solutions. Protein concentration ranges of ~2 to 100 ?g mL(-1) were employed and the recovery characteristics determined through UV-Vis absorbance spectrophotometry for protein quantification. The protein loading capacities across the range of proteins was ~1.5 ?g for the 5 mg fiber tips. Average recoveries from PBS were determined for each protein sample; cytochrome c ~86%, lysozyme ~80%, myoglobin ~86%, and glucose oxidase ~89%. Recoveries from more complex matrices, synthetic urine and synthetic saliva, were determined to be ~90%. A 10× dilution study for a fixed 1 ?g protein application yielded 94 ± 3.2% recoveries. The C-CP tips provided significantly higher recoveries for myoglobin in a 150 mM PBS matrix in comparison to a commercially available protein SPE product, with the added advantages of low cost, rapid processing, and reusability. PMID:23223274

Burdette, Carolyn Q; Marcus, R Kenneth

2013-02-21

169

Effect of chloride ion on the anodic polarization behavior of the Zr 65Al 7.5Ni 10Cu 17.5 amorphous alloy in phosphate buffered solution  

Microsoft Academic Search

The corrosion behavior of the Zr65Al7.5Ni10Cu17.5 amorphous alloy was investigated in a phosphate buffered saline solution and in phosphate–citric acid buffered solutions with various chloride-ion concentrations from 0 to 1.0 M, to examine the performance of the alloy as a biomaterial. The surface condition of the non-polarized and polarized alloy in the passive region was characterized using X-ray photoelectron spectroscopy.

S. Hiromoto; A.-P. Tsai; M. Sumita; T. Hanawa

2000-01-01

170

Propensity of Formate, Acetate, Benzoate, and Phenolate for the Aqueous Solution\\/Vapor Interface: Surface Tension Measurements and Molecular Dynamics Simulations  

Microsoft Academic Search

Abstract The properties of a series of aliphatic and aromatic carboxylates and phenolate mimicking functional groups of humic acid is discussed as far as their behavior in aqueous solutions close to the surface is concerned. Both surface tension measurements,and MD simulations confirm that sodium formate behaves in accord with the classical theory of surfaces of electrolytes,whereas sodium acetate and, much

Babak Minofar; Pavel Jungwirth; Manash R. Das; Werner Kunz; S. Mahiuddin

2007-01-01

171

Effects of dissolved gas species on ultrasonic degradation of (4-chloro-2-methylphenoxy) acetic acid (MCPA) in aqueous solution.  

PubMed

Sonochemical degradation of MCPA ((4-chloro-2-methylphenoxy) acetic acid) in dilute aqueous solutions was studied using ultrasound with a frequency of 500 kHz. The effect of gas atmosphere on MCPA degradation was investigated in nitrogen (N(2)), air (O(2)/N(2)), oxygen (O(2)), argon (Ar) and Ar/O(2) (60/40% v/v) atmospheres. For sonochemical degradation of MCPA in N(2), air (O(2)/N(2)), O(2) and Ar atmospheres, the rate enhancement of MCPA decomposition by sonolysis was found to be more effective in an O(2)-enriched atmosphere compared to Ar atmosphere. It was considered that a higher amount of oxidants was formed in a higher O(2) partial pressure, which accelerated MCPA decomposition in a radical reaction system. On the other hand, both dechlorination and total organic carbon (TOC) removal rates were higher in Ar atmosphere, compared to those in O(2)/N(2) atmosphere. It was found that, MCPA was most effectively decomposed by sonication in Ar/O(2) (60/40% v/v) atmosphere, with higher rates of decomposition, dechlorination and TOC removal. PMID:15590310

Kojima, Yoshihiro; Fujita, Takafumi; Ona, Erwin P; Matsuda, Hitoki; Koda, Shinobu; Tanahashi, Naoki; Asakura, Yoshiyuki

2005-04-01

172

Diffusivity and solubility measurement of oxygen in water–acetic acid–sodium acetate solutions on a rotating ring disc electrode  

Microsoft Academic Search

The measurement of oxygen transit time from ring to disc of a rotating ring disc electrode was used to determine the diffusivity of oxygen. The solubility of oxygen under atmospheric pressure was deduced from measurement of the limiting current of oxygen reduction in a saturated solution. The density and the kinematic viscosity of the solutions were also measured. The correlations

J. Lozar; B. Bachelot; G. Falgayrac; A. Savall

1998-01-01

173

Hierarchical buffered routing tree generation  

Microsoft Academic Search

This paper presents a solution to the problem of per- formance-driven buffered routing tree generation for VLSI cir- cuits. Using a novel bottom-up construction algorithm and a local neighborhood search strategy, our polynomial time algorithm finds the optimum solution in an exponential-size solution sub- space. The final output is a buffered rectilinear Steiner routing tree that connects the driver of

Amir H. Salek; Jinan Lou; Massoud Pedram

2002-01-01

174

Buffer Biology.  

ERIC Educational Resources Information Center

|Presents a science experiment in which students test the buffering capacity of household products such as shampoo, hand lotion, fizzies candy, and cola. Lists the standards addressed in this experiment and gives an example of a student lab write-up. (YDS)|

Morgan, Kelly

2000-01-01

175

Electrochemical noise and impedance study of aluminium in weakly acid chloride solution  

Microsoft Academic Search

The electrochemical noise (EN) characteristics of pure aluminium in unbuffered potassium chloride solution and with acetic acid\\/sodium acetate buffer at pH 5.4 and 4.3 have been analysed to throw light on the influence of pH and of the presence of buffer at the aluminium surface on chloride ion-induced corrosion. Comparison has been made with results obtained by electrochemical impedance spectroscopy

Carla Gouveia-Caridade; M. Isabel S. Pereira; Christopher M. A. Brett

2004-01-01

176

Transbuccal delivery of 5-aza-2 -deoxycytidine: effects of drug concentration, buffer solution, and bile salts on permeation.  

PubMed

Delivery of 5-aza-2 -deoxycytidine (decitabine) across porcine buccal mucosa was evaluated as an alternative to the complex intravenous infusion regimen currently used to administer the drug. A reproducible high-performance liquid chromatography method was developed and optimized for the quantitative determination of this drug. Decitabine showed a concentration-dependent passive diffusion process across porcine buccal mucosa. An increase in the ionic strength of the phosphate buffer from 100 to 400 mM decreased the flux from 3.57 +/- 0.65 to 1.89 +/- 0.61 microg/h/cm2. Trihydroxy bile salts significantly enhanced the flux of decitabine at a 100 mM concentration (P > .05). The steady-state flux of decitabine in the presence of 100 mM of sodium taurocholate and sodium glycocholate was 52.65 +/- 9.48 and 85.22 +/- 7.61 microg/cm2/h, respectively. Two dihydroxy bile salts, sodium deoxytaurocholate and sodium deoxyglycocholate, showed better enhancement effect than did trihydroxy bile salts. A 38-fold enhancement in flux was achieved with 10 mM of sodium deoxyglycocholate. PMID:17915805

Mahalingam, Ravichandran; Ravivarapu, Harish; Redkar, Sanjeev; Li, Xiaoling; Jasti, Bhaskara R

2007-07-13

177

Buffer Mass Test - Buffer Materials.  

National Technical Information Service (NTIS)

Commercial Na bentonite (MX-80) is the clay component of the buffer material in the heater holes as well of the tunnel backfill. Important characteristics are the clay content, liquid limit, X-ray diffraction pattern, water content, and degree of granulat...

R. Pusch L. Boergesson J. Nilsson

1982-01-01

178

In-Line Desalting of Proteins from Buffer and Synthetic Urine Solution Prior to ESI-MS Analysis via a Capillary-Channeled Polymer Fiber Microcolumn  

NASA Astrophysics Data System (ADS)

Presented here is a novel in-line solid phase extraction (SPE) method utilizing a capillary-channeled polymer (C-CP) fiber microcolumn prior to introduction to an electrospray ionization (ESI) source. The high permeability of the microcolumn allows for operation under syringe pump or HPLC driven flow, ultimately providing greater mass spectral clarity and accurate molecular weight determinations for different protein/buffer combinations. Studies presented here focus on the desalting of several target proteins from a standard phosphate buffered saline (PBS) matrix and a synthetic urine solution prior to ESI-MS determinations. In every case, responses for ?M-level proteins in PBS improve from the situation of not permitting molecular weight determinations to values that are precise to better than ±10 Da, without internal standards, with relative improvements in the signal-to-background ratios (S/B) on the order of 3,000×. De-salting of a myoglobin-spiked (12 ?M) synthetic urine results in equally-improved spectral quality.

Burdette, Carolyn Q.; Marcus, R. Kenneth

2013-06-01

179

In-line desalting of proteins from buffer and synthetic urine solution prior to ESI-MS analysis via a capillary-channeled polymer fiber microcolumn.  

PubMed

Presented here is a novel in-line solid phase extraction (SPE) method utilizing a capillary-channeled polymer (C-CP) fiber microcolumn prior to introduction to an electrospray ionization (ESI) source. The high permeability of the microcolumn allows for operation under syringe pump or HPLC driven flow, ultimately providing greater mass spectral clarity and accurate molecular weight determinations for different protein/buffer combinations. Studies presented here focus on the desalting of several target proteins from a standard phosphate buffered saline (PBS) matrix and a synthetic urine solution prior to ESI-MS determinations. In every case, responses for ?M-level proteins in PBS improve from the situation of not permitting molecular weight determinations to values that are precise to better than ±10 Da, without internal standards, with relative improvements in the signal-to-background ratios (S/B) on the order of 3,000×. De-salting of a myoglobin-spiked (12 ?M) synthetic urine results in equally-improved spectral quality. PMID:23463546

Burdette, Carolyn Q; Marcus, R Kenneth

2013-03-05

180

Internal acid buffering in San Joaquin Valley fog drops and its influence on aerosol processing  

NASA Astrophysics Data System (ADS)

Although several chemical pathways exist for S(IV) oxidation in fogs and clouds, many are self-limiting: as sulfuric acid is produced and the drop pH declines, the rates of these pathways also decline. Some of the acid that is produced can be buffered by uptake of gaseous ammonia. Additional internal buffering can result from protonation of weak and strong bases present in solution. Acid titrations of high pH fog samples (median pH=6.49) collected in California's San Joaquin Valley reveal the presence of considerable internal acid buffering. In samples collected at a rural location, the observed internal buffering could be nearly accounted for based on concentrations of ammonia and bicarbonate present in solution. In samples collected in the cities of Fresno and Bakersfield, however, significant additional, unexplained buffering was present over a pH range extending from approximately four to seven. The additional buffering was found to be associated with dissolved compounds in the fogwater. It could not be accounted for by measured concentrations of low molecular weight ( C1- C3) carboxylic acids, S(IV), phosphate, or nitrophenols. The amount of unexplained buffering in individual fog samples was found to correlate strongly with the sum of sample acetate and formate concentrations, suggesting that unmeasured organic species may be important contributors. Simulation of a Bakersfield fog episode with and without the additional, unexplained buffering revealed a significant impact on the fog chemistry. When the additional buffering was included, the simulated fog pH remained 0.3-0.7 pH units higher and the amount of sulfate present after the fog evaporated was increased by 50%. Including the additional buffering in the model simulation did not affect fogwater nitrate concentrations and was found to slightly decrease ammonium concentrations. The magnitude of the buffering effect on aqueous sulfate production is sensitive to the amount of ozone present to oxidize S(IV) in these high pH fogs.

Collett, Jeffrey L.; Hoag, Katherine J.; Rao, Xin; Pandis, Spyros N.

181

Densities and excess molar volumes of formic acid, acetic acid and propionic acid in pure water and in water?+?Surf Excel solutions at different temperatures  

Microsoft Academic Search

Densities, ? of the systems formic acid, acetic acid and propionic acid in water and in 0.05% and 0.1% Surf Excel (SE) solutions in water were measured at temperatures 303.15, 308.15, 313.15, 318.15 and 323.15?K respectively covering the whole composition range. Excess molar volumes, for the systems were found to be negative and their values were found to increase with

M. A. Motin; M. H. Kabir; E. M. Huque

2005-01-01

182

Batch adsorption of 2,4-dichlorophenoxy-acetic acid (2,4-D) from aqueous solution by granular activated carbon  

Microsoft Academic Search

Adsorption equilibrium, kinetics and thermodynamics of 2,4-dichlorophenoxy-acetic acid (2,4-D), one of the most commonly used phenoxy acid herbicides, onto granular activated carbon were studied in aqueous solution in a batch system with respect to pH, temperature and initial 2,4-D concentration. At 600 mg l?1 initial 2,4-D concentration activated carbon exhibited the highest 2,4-D uptake capacity of 518.0 mg g?1 at

Z. Aksu; E. Kabasakal

2004-01-01

183

Crystal structures of TiO2 thin coatings prepared from the alkoxide solution via the dip-coating technique affecting the photocatalytic decomposition of aqueous acetic acid  

Microsoft Academic Search

TiO2 coatings with different crystal structures were prepared from alkoxide solutions via the dip-coating technique. The physical properties, except the crystal structure, were adjusted to distinguish the effect of crystal structure on their photocatalytic property. The results of photocatalytic measurements using TiO2 coatings with different crystal structures showed that the decomposition of aqueous acetic acid was enhanced by the content

K. Kato; A. Tsuzuki; H. Taoda; Y. Torii; T. Kato; Y. Butsugan

1994-01-01

184

Effect of magnesium acetate on the volumetric and transport behavior of some amino acids in aqueous solutions at 298.15 K  

Microsoft Academic Search

Densities, ?, and viscosities, ?, of glycine, dl-?-alanine, dl-?-amino-n-butyric acid, l-leucine and l-phenylalanine in 0.5, 1.0, 1.5 and 2.0 mB of aqueous magnesium acetate solutions at 298.15K have been measured as a function of concentration of amino acids using vibrating tube-digital densimeter and Ubbelohde capillary type viscometer, respectively. The apparent molar volumes, V?, and relative viscosities, ?r, of amino acids

Tarlok S. Banipal; Damanjit Kaur; Parampaul K. Banipal

2006-01-01

185

Method for regeneration of electroless nickel plating solution  

Microsoft Academic Search

An electroless nickel(EN)\\/hypophosphite plating bath is provided employing acetic acid\\/acetate as a buffer and which is, as a result, capable of perpetual regeneration while avoiding the production of hazardous waste. A regeneration process is provided to process the spent EN plating bath solution. A concentrated starter and replenishment solution is provided for ease of operation of the plating bath. The

Eisenmann

1997-01-01

186

Influence of a polymeric solution buffer layer on the chemical bath deposition of polycrystalline PbS films  

Microsoft Academic Search

Polycrystalline thin films of PbS grown on glass substrates previously coated with PbS colloidal particles in a polyvinyl alcohol solution were obtained by chemical bath deposition (CBD). The X-ray diffraction procedures showed evidence of polycrystalline films of cubic PbS with a preferred normal orientation of the planes [100] with the growth direction. The film texture showed a strong influence of

Y. González-Alfaro; F. A. Fernández-Lima; E. M. Larramendi; H. D. Fonseca Filho; M. E. H. Maia da Costa; F. L. Freire Jr.; R. Prioli; R. R. de Avillez; E. F. da Silveira; O. Calzadilla; O. de Melo; E. Pedrero; E. Hernández

2005-01-01

187

Sodium Acetate Hand Warmers  

NSDL National Science Digital Library

In this activity, sodium acetate hand warmers are used to introduce learners to supersaturated solutions, crystallization, and exothermic reactions. This activity guide includes background information, extension ideas, and resources.

Johnson, Jill

2006-01-01

188

DETERMINATION OF TECHNETIUM BY CONTROLLED-POTENTIAL COULOMETRIC TITRATION IN BUFFERED SODIUM TRIPOLYPHOSPHATE MEDIUM  

Microsoft Academic Search

A controlled-potential coulometric method for the determination of Tc ; was developed whereby Tc(VII) is titrated in an acetate-buffered (pH 4.7) ; solution of sodium tripolyphosphate at a potential of --0.70 volt vs S.C.E. In ; the range from about 0.5 to 5 mg of Tc(VII) titrated, the relative error of the ; method is about 450 deg C in

A. A. Terry; H. E. Zittel

1963-01-01

189

Studies on the in vivo absorption of micellar solutions of tocopherol and tocopheryl acetate in the rat: demonstration and partial characterization of a mucosal esterase localized to the endoplasmic reticulum of the enterocyte  

Microsoft Academic Search

The in vivo absorption of a-tocopherol from micellar solubilized solutions of free a-tocopherol and a- tocopheryl acetate was investigated using isolated loops of ratjejunum and found to be similar. Although analysis of the fluid remaining in the loop following the absorptive period with tocopheryl acetate showed that esterase activity and free tocopherol were present, calculations suggested that luminal hydrolysis of

P. M. Mathias; J. T. Harries; T. J. Peters; D. P. R. Muller

190

Solubility of sulfur dioxide in aqueous solutions of acetic acid, sodium acetate, and ammonium acetate in the temperature range from 313 to 393 K at pressures up to 3.3 MPa: Experimental results and comparison with correlations\\/predictions  

Microsoft Academic Search

In many chemical plants, for example in coal gasification processes or desulfurization equipment, sour gas absorption columns and sour water strippers are used to remove weak electrolyte gases like sulfur dioxide, hydrogen cyanide, hydrogen sulfide or carbon dioxide from aqueous solutions. The basic design of such equipment requires physico-chemical models to describe the phase equilibrium as well as the caloric

Jianzhong Xia; Bernd Rumpf; Gerd Maurer

1999-01-01

191

New process for producing cellulose acetate from wood in concentrated acetic acid  

Microsoft Academic Search

To explore further potential applications of acetic acid pulp, an investigation was conducted to develop a direct method for producing cellulose acetate from wood in combination with atmospheric acetic acid pulping. The process consists of delignification, totally chlorine-free bleaching, and esterification, with the concentrated acetic acid aqueous solution being used as only solvent throughout the process. The acetic acid pulp

Hironori Sato; Yasumitsu Uraki; Takao Kishimoto; Yoshihiro Sano

2003-01-01

192

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.  

PubMed

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. PMID:16956724

Cang, Long; Zhou, Dong-Mei; Alshawabkeh, Akram N; Chen, Hai-Feng

2006-08-03

193

Diffusion of lonizable Solutes Across Planar Lipid Bilayer Membranes: Boundary-Layer pH Gradients and the Effect of Buffers  

Microsoft Academic Search

The diffusion of weak acids or bases across planar lipid bilayer membranes results in aqueous boundary layer pH gradients. If not properly taken into account, such pH gradients will lead to errors in estimated membrane permeability coefficients, Pm. The role of the permeant concentration, the buffer capacity, and the physicochemical properties of both permeant and buffer on the magnitude and

Tian-xiang Xiang; Bradley D. Anderson

1993-01-01

194

An experimental study of zinc chloride speciation from 300 to 600 ??C and 0.5 to 2.0 kbar in buffered hydrothermal solutions  

USGS Publications Warehouse

The solubility of sphalerite (ZnS) was measured in KCl-HCl-H2O solutions at 300-600??C and 0.5-2.0 kbar. The silicate assemblage K-feldspar-muscovite (or andalusite)-quartz was used to buffer the solution to acid conditions, resulting in the total solubility reaction 2K+ + KAl2AlSi3O10(OH)2 + 6SiO2 + ZnS + nCl- = ZnCln(2-n) + 3KAlSi3O8 + H2S. (muscovite) (quartz) (sphalerite) (K-feldspar) A computer retrieval technique was used to derive average chloride ligand numbers for chlorozinc species at 0.25-2.0 molal total chloride. This technique mathematically solves for the average ligand number using a series of pertinent chemical relations at P and T. Mono- and di-chlorozinc species were found to predominate throughout the pressure-temperature-composition range investigated. The logarithms of the first and second dissociation constants for ZnCl20 were evaluated over the P-T range; for example, at 1 kbar, the values -0.41 and -1.42 were computed for the logarithm of the first dissociation constant, while -7.62 and -10.57 were computed for the logarithm of the second dissociation constant, for 400 and 500??C, respectively. Results are compared to past studies conducted at subcritical conditions and differ in that we find no evidence for more highly coordinated chloro-zinc species except possibly for ZnCl3- at 600??C, 1 and 2 kbar. Our results are consistent with electrostatic theory, which favors lower charged to neutral molecules in low dielectric-constant media. ?? 1994.

Cygan, G. L.; Hemley, J. J.; d'Angelo, W. M.

1994-01-01

195

Understanding, Deriving, and Computing Buffer Capacity  

NASA Astrophysics Data System (ADS)

The concept of buffer capacity appears in varied disciplines, including bio-, geo-, analytical, and environmental chemistry, physiology, medicine, dentistry, and agriculture. Unfortunately, however, derivation and systematic calculation of buffer capacity is a topic that seems to be neglected in the undergraduate analytical chemistry curriculum. In this work, we give an account of the development of the buffer capacity concept and derive the buffer capacity contribution equations for buffer systems containing mono-, di-, and triprotic weak acids (and their conjugate bases) and aluminum(III), which undergoes hydrolysis. A brief review of pH is provided because pH is involved in applying buffer capacity to the real world. In addition, we discuss evaluation of the equations, numerical approximation of buffer capacity when an analytic solution is not derived, and the mathematical properties of the buffer capacity expressions.

Urbansky, Edward T.; Schock, Michael R.

2000-12-01

196

Acid dissociation constants and pH values for standard "bes" and "tricine" buffer solutions in 30, 40, and 50 mass% dimethyl sulfoxide/water between 25 and -25 degrees C.  

PubMed

Information is given concerning two standard buffer solutions suitable as pH references in 30, 40, and 50 mass% dimethyl sulfoxide (DMSO)/H2O mixed solvents at subzero temperatures from -20 to 0 degrees C, with the intention of establishing a pH (designated pH*) scale. The two buffers selected were the ampholytes N,N-bis(2-hydroxyethyl)-2-aminoethane sulfonic acid ("bes") and N-tris(hydroxymethyl)methylglycine ("tricine"), and the reference standard consisted of equal molal quantities of the buffer and its respective sodium salt. The assignment of pH* values was based on measurements of the emf of cells without liquid junction of the type: Pt;H2(g,l atm) /Bes, Na Besate, NaCl / AgCl;Ag and Pt;H2(g,l atm) /Tricine, Na Tricinate, NaCl /AgCl;Ag and the pH* was derived from a determination of K2, the equilibrium constant for the dissociation process (Buffer)+/- in equilibrium with(Buffer)- + H+. PMID:3000691

Roy, R N; Gibbons, J J; Baker, G E

1985-12-01

197

STUDY ON THE EXTRACTION EQUILIBRIUM OF TILMICOSIN BETWEEN THE AQUEOUS AND BUTYL ACETATE PHASES  

Microsoft Academic Search

Tilmicosin is a semi-synthetic macrolide derivative of tylosin. The production process of tilmicosin involved extraction using butyl acetate and subsequent stripping using an aqueous buffer solution. In this work, the effect of pH on the solubility of tilmicosin in its aqueous phase was examined. It was found that the solubility of tilmicosin is much higher at a low pH than

Zhinan Xu; Jun Wang; Wenhe Shen; Peilin Cen

2006-01-01

198

Buffer Dimensioning for Delay and Loss-Sensitive Traffic  

Microsoft Academic Search

Multiplexing of delay- and loss-sensitive traffic requires a common analytical framework for buffer dimensioning, buffer sharing schemes, as well as buffer entry and exit priorities. This paper performs a relevant study by employing discrete-time queueing techniques, appropriate for the small buffer sizes envisaged in ATM technology. The model, solution method and relevant metrics are presented. The numerical results are critically

Kimon P Kontovassilis; John T Tsiligaridis; George I. Stassinopoulos

1995-01-01

199

Morphological and phase evolution of TiO{sub 2} nanocrystals prepared from peroxotitanate complex aqueous solution: Influence of acetic acid  

SciTech Connect

Nanosized anatase and rutile TiO{sub 2} having different shape, phase and size have been prepared from aqueous solutions of peroxo titanium complex starting from titanium(IV) isopropoxide (TTIP), acetic acid and hydrogen peroxide (H{sub 2}O{sub 2}) in water/isopropanol media by a facile sol-gel process. The TiO{sub 2} nanocrystals are characterized by powder X-ray diffraction (XRD), Raman spectroscopy, FT-IR spectroscopy, TEM, high resolution transmission electron microscopy (HRTEM) and selected area electron diffraction (SAED) techniques. The influence of pH and the sequence of addition of reaction contents on the phase and morphology of TiO{sub 2} are studied. The reasons for the observation of only anatase and/or mixture of anatase and rutile are given. - Graphical abstract: The morphology of TiO{sub 2} depends on the sequence of addition of AcOH and H{sub 2}O{sub 2} from the system of titanium isopropoxide and acetic acid (AcOH) in the presence of H{sub 2}O{sub 2}.

Chang, Jeong Ah; Vithal, Muga; Baek, In Chan [KRICT-EPFL Global Research Laboratory, Advanced Materials Division, Korea Research Institute of Chemical Technology, 19 Sinseongno, Yuseong, Daejeon 305-600 (Korea, Republic of); Seok, Sang Il, E-mail: seoksi@krict.re.k [KRICT-EPFL Global Research Laboratory, Advanced Materials Division, Korea Research Institute of Chemical Technology, 19 Sinseongno, Yuseong, Daejeon 305-600 (Korea, Republic of)

2009-04-15

200

An all chemical solution deposition approach for the growth of highly textured CeO2 cap layers on La2Zr2O7-buffered long lengths of biaxially textured Ni W substrates for YBCO-coated conductors  

NASA Astrophysics Data System (ADS)

A reel-to-reel, dip coating process has been developed to continuously deposit epitaxial La2Zr2O7 (LZO) and CeO2 on 5 m long cube-textured {100} (001)Ni tapes. Recent results for La2Zr2O7 and CeO2 buffer layers deposited on long lengths of Ni substrate for the realization of YBa2Cu3O7-x (YBCO)-coated conductors are presented. The major achievement is the development of a new all chemical solution deposition (CSD) process leading to the formation of highly textured buffer layers at moderate annealing temperatures. Reproducible highly textured, dense and crack-free LZO buffer layers and CeO2 cap layers were obtained for annealing temperatures as low as 900 °C in a reducing atmosphere (Ar-5 at.%-H2). The thickness of the LZO buffer layers was determined to be (200 ± 10) nm per single coating; prepared cerium oxide layers showed a thickness of 60 nm ± 10 nm. Pulsed laser deposition (PLD) was used to grow YBCO films on these substrates. A Tc 0 of T = 90.5 K and ?Tc = 1.4 K was obtained on PLD-YBCO/CSD-CeO2 /CSD-LZO/Ni-5 at.% W, which shows the outstanding features of this new buffer layer architecture processed by CSD. The large layer thickness combined with low annealing temperatures is the main advantage of this new process for low-cost buffer layer deposition on Ni-RABiTS (rolling-assisted biaxially textured substrates).

Engel, S.; Knoth, K.; Hühne, R.; Schultz, L.; Holzapfel, B.

2005-10-01

201

Volumetric Investigations on Interactions of Acidic\\/Basic Amino Acids with Sodium Acetate, Sodium Propionate and Sodium Butyrate in Aqueous Solutions  

Microsoft Academic Search

The apparent molar volumes, V\\u000a \\u000a ?\\u000a , of L-aspartic acid, L-glutamic acid, L-lysine monohydrate and L-arginine in water and in aqueous (0.1, 0.25, 0.5 and 1.0)\\u000a mol?kg?1 sodium acetate and sodium propionate, and (0.1, 0.25 and 0.5) mol?kg?1 sodium butyrate solutions have been determined at 288.15, 298.15, 308.15 and 318.15 K from density measurements. The partial\\u000a molar volumes at infinite dilution, V\\u000a 2o, obtained

Tarlok S. Banipal; Kultar Singh; Parampaul K. Banipal

2007-01-01

202

Effects of feed physical form and buffering solutes on water disappearance and proximal stomach pH in swine1,2  

Microsoft Academic Search

The effects of the physical form of feed on water disappearance and the effects of buffered wa- ter on proximal stomach pH in swine were determined in two experiments. In Exp. 1, 32 barrows were used to evaluate the water disappearance in pigs fed a finely ground and pelleted diet vs those fed a coarsely ground and mashed diet for

K. D. Ange; J. H. Eisemann; R. A. Argenzio; G. W. Almond; A. T. Blikslager

203

Properties of Pb(0.92)La(0.08)Zr(0.52)Ti(0.48)O(3) thin films grown on SrRuO(3) buffered nickel and silicon substrates by chemical solution deposition  

SciTech Connect

Ferroelectric film-on-foil capacitors are suitable to replace discrete passive components in the quest to develop electronic devices that show superior performance and are smaller in size. The film-on-foil approach is the most practical method to fabricate such components. Films of Pb{sub 0.92}La{sub 0.08}Zr{sub 0.52}Ti{sub 0.48}O{sub 3} (PLZT) were deposited on SrRuO{sub 3} (SRO) buffer films over nickel and silicon substrates. High-quality polycrystalline SRO thin-film electrodes were first deposited by chemical solution deposition. A phase pure, dense, uniform microstructure with grain size <100 nm was obtained in films crystallized at 700 C. The room-temperature resistivity of the SRO films crystallized at 700 C was {approx}800-900 {mu}{Omega}-cm. The dielectric properties of sol-gel derived PLZT capacitors on SRO-buffered nickel were evaluated as a function of temperature, bias field, and frequency, and the results were compared to those of the same films on silicon substrates. The comparison demonstrated the integrity of the buffer layer and its compatibility with nickel substrates. Device-quality dielectric properties were measured on PLZT films deposited on SRO-buffered nickel foils and found to be superior to those for PLZT on SRO-buffered silicon and expensive platinized silicon. These results suggest that SRO films can act as an effective barrier layer on nickel substrates suitable for embedded capacitor applications.

Narayanan, M.; Ma, B.; Tong, S.; Koritala, R.; Balachandran, U. (Energy Systems); ( MSD)

2012-01-01

204

Dependence of Device Characteristics of Bulk-Heterojunction Organic Thin-Film Solar Cells on Concentration of Glycerol and Sorbitol Addition in Pedot:. PSS Solutions for Fabricating Buffer Layers  

NASA Astrophysics Data System (ADS)

We have investigated the dependence of device characteristics of bulk-heterojunction organic thin-film solar cells on the concentration of glycerol and sorbitol addition in poly(3,4-ethylenedioxy thiophene):poly(4-styrene sulfonate) (PEDOT:PSS) solutions for fabricating buffer layers. The device structure is ITO/buffer/regioregular poly(3-hexylthiophene) (P3HT):[6,6]-phenyl C61-butyric acid methylester (PCBM)/Al. Glycerol addition is effective for increasing power conversion efficiency (PCE) from 1.25 to 1.41% because of the increase in short-circuit current density (Jsc) without decreasing open-circuit voltage (Voc). On the other hand, sorbitol addition decreases PCE from 1.25 to 1.04%, owing to the decrease in Voc. This difference in Voc behavior is ascribed to different work function of PEDOT:PSS with glycerol and sorbitol treatment.

Yamaki, Yusuke; Marumoto, Kazuhiro; Fujimori, Takuya; Mori, Tatsuo

205

Hemodynamic Effects of Peritoneal Dialysis Solutions on the Rat Peritoneal Membrane: Role of Acidity, Buffer Choice, Glucose Concentration, and Glucose Degradation Products  

Microsoft Academic Search

Conventional peritoneal dialysis fluids (PDF) are unphysiologic because of their hypertonicity, high glucose and lactate concentrations, acidic pH, and presence of glucose degradation products (GDP). Long-term exposure to conven- tional PDF may cause functional and structural alterations of the peritoneal membrane. New PDF have a neutral pH, a low GDP content, and contain bicarbonate or lactate as the buffer. Intravital

SISKA MORTIER; S. DE VRIESE; JOHAN VAN DE VOORDE; THOMAS P. SCHAUB; JUTTA PASSLICK-DEETJEN; NORBERT H. LAMEIRE

2002-01-01

206

Meshless steady-state analysis of chemo-electro-mechanical coupling behavior of pH-sensitive hydrogel in buffered solution  

Microsoft Academic Search

The objective of the present study is to simulate the phenomenological behavior of the pH-sensitive hydrogels when the pH of their buffered aqueous environment is changed. A chemo-electro-mechanical formulation, referred to as the multi-effect-coupling pH-stimulus (MECpH) model, is also presented. This mathematical model, consisting of coupled nonlinear partial differential equations, takes account of the diffusion of ionic species, electric potential

Hua Li; Y. K. Yew; T. Y. Ng; K. Y. Lam

2005-01-01

207

Solution (sup13)C Nuclear Magnetic Resonance Spectroscopic Analysis of the Amino Acids of Methanosphaera stadtmanae: Biosynthesis and Origin of One-Carbon Units from Acetate and Carbon Dioxide  

PubMed Central

We found that general pathways for amino acid synthesis of Methanosphaera stadtmanae, a methanogen that forms CH(inf4) from H(inf2) and methanol, resembled those of methanogens that form CH(inf4) from CO(inf2) or from the methyl group of acetate. We determined the incorporation of (sup14)C-labeled CO(inf2), formate, methanol, methionine, serine, and acetate into cell macromolecules. Labeling of amino acid carbons was determined by solution nuclear magnetic resonance spectroscopy after growth with (sup13)C-labeled acetate, CO(inf2), serine, and methanol. The (alpha) and (beta) carbons of serine and alanine were formed from carboxyl and methyl carbons of acetate, respectively, and the amino acid carboxyl groups were formed from CO(inf2). This indicates that pyruvate was formed by reductive carboxylation of acetate. Labeling of the methyl carbon of methionine indicated that the major route of synthesis was from the hydroxymethyl carbon of serine that arises from the methyl carbon of acetate. Methanol was a minor source of the methyl of methionine. Unambiguous assignment was made of the sources of all carbons of histidine. Labeling of the histidine 7 position ((epsilon) carbon) was consistent with formation from the C-2 of the purine ring of ATP and the origin of the C-2 from a formyl unit derived from the hydroxymethyl carbon of serine.

Miller, T. L.; Chen, X.; Yan, B.; Bank, S.

1995-01-01

208

Sizing router buffers  

Microsoft Academic Search

All Internet routers contain buffers to hold packets during times of congestion. Today, the size of the buffers is determined by the dynamics of TCP's congestion control algorithm. In particular, the goal is to make sure that when a link is congested, it is busy 100% of the time; which is equivalent to making sure its buffer never goes empty.

Guido Appenzeller; Isaac Keslassy; Nick McKeown

2004-01-01

209

An all chemical solution deposition approach for the growth of highly textured CeO2 cap layers on La2Zr2O7-buffered long lengths of biaxially textured Ni W substrates for YBCO-coated conductors  

Microsoft Academic Search

A reel-to-reel, dip coating process has been developed to continuously deposit epitaxial La2Zr2O7 (LZO) and CeO2 on 5 m long cube-textured {100} (001)Ni tapes. Recent results for La2Zr2O7 and CeO2 buffer layers deposited on long lengths of Ni substrate for the realization of YBa2Cu3O7-x (YBCO)-coated conductors are presented. The major achievement is the development of a new all chemical solution

S. Engel; K. Knoth; R. Hühne; L. Schultz; B. Holzapfel

2005-01-01

210

Preparation and application of functionalized cellulose acetate/silica composite nanofibrous membrane via electrospinning for Cr(VI) ion removal from aqueous solution.  

PubMed

Novel NH(2)-functionalized cellulose acetate (CA)/silica composite nanofibrous membranes were successfully prepared by sol-gel combined with electrospinning technology. Tetraethoxysilane (TEOS) as a silica source, CA as precursor and 3-ureidopropyltriethoxysilane as a coupling agent were used in membrane preparation. The membrane's chemical and morphological structures were investigated by scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM) images, X-ray diffraction (XRD), element analyzer, Fourier-transform infrared spectroscopy (FTIR) and N(2) adsorption-desorption isotherms. The composite nanofibrous membranes exhibited high surface area and porosity. The membranes were used for Cr(VI) ion removal from aqueous solution through static and dynamic experiments. The adsorption behavior of Cr(VI) can be well described by the Langmuir adsorption model, and the maximum adsorption capacity for Cr(VI) is estimated to be 19.46 mg/g. The membrane can be conveniently regenerated by alkalization. Thus the composite membrane prepared from biodegradable raw material has potential applications in the field of water treatment. PMID:22858801

Taha, Ahmed A; Wu, Yi-na; Wang, Hongtao; Li, Fengting

2012-08-02

211

A Buffer that Mimics the SMP Buffer for Determining Lime Requirement of Soil  

Microsoft Academic Search

The Shoemaker-McLean-Pratt (SMP) buffer used for determining lime requirement of soil contains chromium and p-nitrophenol, which classifies the solution as a hazardous waste. A buffer without hazard- ous chemicals producing the same pH as SMP buffer would eliminate hazardous waste and have no effect on agronomic interpretation. Chemicals chosen to replace chromium and p-nitrophenol were 2-(N- morpholino)ethanesulfonic acid monohydrate (MES)

F. J. Sikora

2006-01-01

212

Chemical solution deposition (CSD) of CeO2 and La2Zr2O7 buffer layers on cube textured NiW substrates  

NASA Astrophysics Data System (ADS)

We present results of crack free layers of CeO2 and La2Zr2O7 deposited by means of CSD on cube textured Ni-4 at.% W substrates. EBSD-data show histograms with very good inplane- and out-of-plane textures and were used to simulate the critical current density in the YBCO layer. The surface roughness, a sensitive feature for good deposition results, was analyzed with a profilometer. In the CSD process we applied, the 2, 4-pentanedionates of the metal cations in glacial acetic acid and methanol served as starting substances.

Kotzyba, G.; Obst, B.; Nast, R.; Goldacker, W.; Holzapfel, B.

2006-06-01

213

Depth buffer shadow algorithms  

SciTech Connect

The depth buffer (also called z-buffer) visible surface algorithm is frequently used for shadow simulation. This shadow algorithm is very powerful, but it suffers from several problems such as aliasing and incorrect self-shadowing of simple surfaces. New algorithms are presented which solve these problems for most cases without much additional computation. A family of depth buffer shadow algorithms is defined. Three main improvements are presented. First, replacing the z-buffer with a p-buffer (plane buffer) gives a more accurate representation of the visible surface across a pixel. Second, storing two surface in the shadow buffer the closest and the second surfaces to the light source, and averaging them to form an intermediate surface yields a much better defined illumination test. Third, considering the values of adjacent pixels in the shadow buffer helps to reduce some aliasing artifacts. These techniques preserve all the desirable properties of the depth buffer visible surface algorithm while yielding more accurate shadows. 12 refs., 17 figs.

Grant, C.W.; Allison, M.J.

1990-02-01

214

Organellar Calcium Buffers  

PubMed Central

Ca2+ is an important intracellular messenger affecting many diverse processes. In eukaryotic cells, Ca2+ storage is achieved within specific intracellular organelles, especially the endoplasmic/sarcoplasmic reticulum, in which Ca2+ is buffered by specific proteins known as Ca2+ buffers. Ca2+ buffers are a diverse group of proteins, varying in their affinities and capacities for Ca2+, but they typically also carry out other functions within the cell. The wide range of organelles containing Ca2+ and the evidence supporting cross-talk between these organelles suggest the existence of a dynamic network of organellar Ca2+ signaling, mediated by a variety of organellar Ca2+ buffers.

Prins, Daniel; Michalak, Marek

2011-01-01

215

Blood buffer values in mineral deficiency  

Microsoft Academic Search

Conclusions  \\u000a \\u000a \\u000a \\u000a 1. \\u000a The buffer values of serum obtained from normal and rachitic infants have been determined electrometrically for the entire\\u000a pH range.\\u000a \\u000a \\u000a \\u000a 2. \\u000a The blood buffer curves of normal and rachitic infants plotted against that of a non-buffered solution show the marked diminution\\u000a in the blood buffer capacity in rickets.\\u000a \\u000a \\u000a \\u000a 3. \\u000a The buffer action of blood is not constant but

I. Newton Kugelmass

1935-01-01

216

Interaction of [Ln(DO2A)(H 2O) 2?3] + and [Ln(DO2P)(H 2O) 2?3] ? with phosphate, acetate and fluoride anions in aqueous solution  

Microsoft Academic Search

Mixed complexation of the lanthanide(III) chelates of the 1,7-disubstituted tetraazacyclododecane macrocycles DO2A and DO2P with phosphate, acetate and fluoride anions was studied in aqueous solutions using high resolution 1H and 31P NMR spectroscopy. The [La(DO2A)(H2O)2?3]+ and [Ce(DO2A)(H2O)2?3]+ chelates readily decompose in aqueous solutions containing phosphate anions. [Nd(DO2A)(H2O)2?3]+ and [Eu(DO2A)(H2O)2?3]+ chelates remain stable in an acetate environment. Association constants for the

K Kimpe; W D’Olieslager; C Görller-Walrand; A Figueirinha; Z Kovács; C. F. G. C Geraldes

2001-01-01

217

Method for regeneration of electroless nickel plating solution  

DOEpatents

An electroless nickel(EN)/hypophosphite plating bath is provided employing acetic acid/acetate as a buffer and which is, as a result, capable of perpetual regeneration while avoiding the production of hazardous waste. A regeneration process is provided to process the spent EN plating bath solution. A concentrated starter and replenishment solution is provided for ease of operation of the plating bath. The regeneration process employs a chelating ion exchange system to remove nickel cations from spent EN plating solution. Phosphites are then removed from the solution by precipitation. The nickel cations are removed from the ion exchange system by elution with hypophosphorus acid and the nickel concentration of the eluate adjusted by addition of nickel salt. The treated solution and adjusted eluate are combined, stabilizer added, and the volume of resulting solution reduced by evaporation to form the bath starter and replenishing solution. 1 fig.

Eisenmann, E.T.

1997-03-11

218

Method for regeneration of electroless nickel plating solution  

SciTech Connect

An electroless nickel(EN)/hypophosphite plating bath is provided employing acetic acid/acetate as a buffer and which is, as a result, capable of perpetual regeneration while avoiding the production of hazardous waste. A regeneration process is provided to process the spent EN plating bath solution. A concentrated starter and replenishment solution is provided for ease of operation of the plating bath. The regeneration process employs a chelating ion exchange system to remove nickel cations from spent EN plating solution. Phosphites are then removed from the solution by precipitation. The nickel cations are removed from the ion exchange system by elution with hypophosphorous acid and the nickel concentration of the eluate adjusted by addition of nickel salt. The treated solution and adjusted eluate are combined, stabilizer added, and the volume of resulting solution reduced by evaporation to form the bath starter and replenishing solution.

Eisenmann, Erhard T. (5423 Vista Sandia, NE., Albuquerque, NM 87111)

1997-01-01

219

Fiber loop optical buffer  

Microsoft Academic Search

Fiber loop optical buffers enable data storage for discrete time intervals and therefore appear suitable for applications in optical asynchronous transfer mode (OATM)-based networks where data are transmitted in cells of fixed length. In this paper, the feasibility and the limitations of optical data storage in a fiber loop optical buffer are studied theoretically and experimentally, A model of a

R. Langenhorst; M. Eiselt; W. Pieper; G. Grosskopf; R. Ludwig; L. Kuller; E. Dietrich; H. G. Weber

1996-01-01

220

Depth buffer shadow algorithms.  

National Technical Information Service (NTIS)

The depth buffer (also called z-buffer) visible surface algorithm is frequently used for shadow simulation. This shadow algorithm is very powerful, but it suffers from several problems such as aliasing and incorrect self-shadowing of simple surfaces. New ...

C. W. Grant M. J. Allison

1990-01-01

221

Catalytic wet-air oxidation of aqueous solutions of formic acid, acetic acid and phenol in a continuous-flow trickle-bed reactor over Ru\\/TiO 2 catalysts  

Microsoft Academic Search

Catalytic wet-air oxidation of aqueous solutions of formic acid, acetic acid and phenol was carried out in a trickle-bed reactor at T=328–523K and total pressures up to 50bar over various Ru\\/TiO2 catalysts. Complete oxidation of formic acid was obtained at mild operating conditions, and no catalyst deactivation occurred that could be attributed to the dissolution of active ingredient material. It

Albin Pintar; Jurka Batista; Tatjana Tišler

2008-01-01

222

[Metabolism of C(14)-acetate by some trematodes  

PubMed

The adult trematodes, Fasciola hepatica, Eurytrema pancreaticum and Paramphistomum cervi, employed in this experiment were obtained from the cattle slaughtered at the local abbatoir. The worms selected and washed several times in normal sterilized saline solution. Each about ten of intact F. hepatica, fourty of E. pancreaticum, and twenty of P. cervi were incubated in 50 cc volume of special incubation flasks with incubation medium consisting of 10 cc. of Krebs-Ringer phosphate buffer(pH 7.4) The incubation medium was added C(14)-1-acetate and non-radioactive carrier Na-acetate so as to contain acetate concentration of 50 mg per cent. The worms were allowed to incubate for 5 hours in the Dubnoff metabolic shaking incubator at 38 degrees C. After incubation period, respiratory CO2 samples from central well of incubation flask were analysed for total CO2 production rate and their specific activity of respiratory CO2. The lactate and pyruvate appearance rates were determined by analyzing the lactate and pyruvate concentration in a medium after incubation. The glycogen samples isolated from worms were analyzed for the tissue concentration and their radioactivities in order to determine the turnover rate of glycogen pool. Radioactivities of these series of experiments were counted by an endwindow Geiger-Muller counter as an infinitely thin samples. The quantitative analysis of C(14)-acetate utilized by F. hepatica, E. pancreaticum and P. cervi were compared and discussed in this report. According to these data of the experiment, it is suggested that the fatty acid such as acetate may play a part of their oxidative process into the respiratory CO2 and the synthetic process into glycogen in the above species of trematodes. PMID:12913583

Seo, Byong Seol; Rim, Han Jong; Min, Yong Ok; Rhee, Sang Don; Lee, Tong Hoon; Yun, Myong Soon

1965-12-01

223

Acetate Induced Enhancement of Photocatalytic Hydrogen Peroxide Production from Oxalic Acid and Dioxygen.  

PubMed

The addition of acetate ion to an O2-saturated mixed solution of acetonitrile and water containing oxalic acid as a reductant and 2-phenyl-4-(1-naphthyl)quinolinium ion (QuPh(+)-NA) as a photocatalyst dramatically enhanced the turnover number of hydrogen peroxide (H2O2) production. In this photocatalytic H2O2 production, a base is required to facilitate deprotonation of oxalic acid forming oxalate dianion, which acts as an actual electron donor, whereas a Brønsted acid is also necessary to protonate O2(•-) for production of H2O2 by disproportionation. The addition of acetate ion to a reaction solution facilitates both the deprotonation of oxalic acid and the protonation of O2(•-) owing to a pH buffer effect. The quantum yield of the photocatalytic H2O2 production under photoirradiation (? = 334 nm) of an O2-saturated acetonitrile-water mixed solution containing acetate ion, oxalic acid and QuPh(+)-NA was determined to be as high as 0.34, which is more than double the quantum yield obtained by using oxalate salt as an electron donor without acetate ion (0.14). In addition, the turnover number of QuPh(+)-NA reached more than 340. The reaction mechanism and the effect of solvent composition on the photocatalytic H2O2 production were scrutinized by using nanosecond laser flash photolysis. PMID:23631436

Yamada, Yusuke; Nomura, Akifumi; Miyahigashi, Takamitsu; Ohkubo, Kei; Fukuzumi, Shunichi

2013-04-30

224

Immunolocalization of MAP-2 in Routinely Formalin-Fixed, Paraffin-Embedded Guinea Pig Brain Sections Using Microwave Irradiation: A Comparison of Different Combinations of Antibody Clones and Antigen Retrieval Buffer Solutions  

NASA Astrophysics Data System (ADS)

The present study was designed to evaluate the efficacy of different microwave pretreatment methods to retrieve microtubule-associated protein 2 (MAP-2) immunoreactivity in formalin-fixed, paraffin-embedded guinea pig brain sections. Brain sections, microwave pretreated in boiling sodium citrate, citric acid, Tris hydrochloride, and EDTA buffers of pH 4, 6, and 8, were labeled with four different clones of MAP-2 monoclonal antibodies. No MAP-2 immunoreactivity was observed in control sections processed without microwave pretreatment. Optimal MAP-2 immunoreactivity was observed only when MAP-2 antibody clone AP18 was used in conjunction with citric acid buffer of pH 6.0. Using this combination, brain sections from nerve agent soman-exposed guinea pigs were found to exhibit marked reduction in MAP-2 immunostaining in the hippocampus. These observations suggest that the clone of the antibody in addition to the type and pH of antigen retrieval (AR) solution are important variables to be considered for establishing an optimal AR technique. When studying counterpart antigens of species other than that to which the antibodies were originally raised, different antibody clones must be tested in combination with different microwave-assisted AR (MAR) methods. This MAR method makes it possible to conduct retrospective studies on archival guinea pig brain paraffin blocks to evaluate changes in neuronal MAP-2 expression as a consequence of chemical warfare nerve agent toxicity.

Kan, Robert K.; Pleva, Christina M.; Hamilton, Tracey A.; Petrali, John P.

2005-04-01

225

New Insights into Buffer-Ionic Salt Interactions: Solubilities, Transfer Gibbs Energies, and Transfer Molar Volumes of TAPS and TAPSO from Water to Aqueous Electrolyte Solutions  

Microsoft Academic Search

The solubilities of N-[tris(hydroxymethyl)methyl]-3-aminopropanesulfonic acid (TAPS) or N-[tris(hydroxymethyl)methyl]-3-amino-2-hydroxypropanesulfonic\\u000a acid (TAPSO) in water and in aqueous solutions of CH3COOK (KAc), KBr, KCl, or NaCl were determined from density measurements at 298.15 K. The solubilities of TAPS in aqueous solution\\u000a decrease with increasing concentration of the salts (salting-out effect), whereas those of TAPSO increase with increasing\\u000a concentration of the salts (salting-in effect). The

Mohamed Taha; Ming-Jer Lee

2010-01-01

226

AN AMINO ACID-BASED PERITONEAL DIALYSIS FLUID BUFFERED WITH BICARBONATE VERSUS GLUCOSE\\/BICARBONATE AND GLUCOSE\\/LACTATE SOLUTIONS: AN INTRAINDIVIDUAL RANDOMIZED STUDY  

Microsoft Academic Search

? ? ? ? ? Patients: Ten nondiabetic patients stable on continu- ous ambulatory peritoneal dialysis (time on dialysis, 42.5 ± 21.5 months) were treated and monitored with the test solutions over a 6-hour dwell. Three different study days followed in a randomized order for each patient (interval of 1 - 3 weeks). Blood and dialysate samples were taken at

Jörg Plum; Christine Erren; Claus Fieseler; Judith Kirchgessner; Jutta Passlick-Deetjen

227

Tri-State Buffer  

NSDL National Science Digital Library

This interactive presentation, created by Terry Bartelt and hosted by the Electromechanical Digital Library, discusses the tri-state buffer used in devices employing digital circuitry. A tri-state buffer is "one type of device that is used in digital circuits receiving two logic states but producing three different types of output signals." The presentation is filled with useful flash animations presenting the buffer's use. Furthermore, a series of slides presents the application of this device in different situations. Once complete, a short four-question quiz is provided to test the full understanding of the different concepts.

Bartelt, Terry L.

2009-04-20

228

Electrochemical deposition of zinc oxide films from non-aqueous solution: a new buffer\\/window process for thin film solar cells  

Microsoft Academic Search

Zinc oxide is a wide band gap semiconductor with wide application in thin film devices such as n-type window layers for thin film solar cells, piezoelectric and luminescent devices, and for catalytic applications. We have cathodically electrodeposited films of ZnO by reduction of dissolved oxygen in a non-aqueous solution (dimethylsulfoxide) containing a Zn salt. This method allows a large deposition

D. Gal; G Hodes; D Lincot; H.-W Schock

2000-01-01

229

Efficient Organic Photovoltaic Cells Using Hole-Transporting MoO3 Buffer Layers Converted from Solution-Processed MoS2 Films  

Microsoft Academic Search

We introduce a new method to fabricate a MoO3 hole-transporting layer for organic photovoltaic cells (OPVs). We fabricated a MoS2 film from its solution and converted it to MoO3. MoS2 has a lamellar crystal structure similar to graphite, and it can be exfoliated into monolayer MoS2 dispersible in water. Li atoms were first intercalated into van der Waals gaps of

Shogo Kato; Ryo Ishikawa; Yosuke Kubo; Hajime Shirai; Keiji Ueno

2011-01-01

230

Evaluation of AmpouledTonometeredBufferSolutions as a Quality ControlSystemfor pH, p2, andPo2Measurement  

Microsoft Academic Search

In response to the need for an adequate quality-control system for blood-pH and blood-gas analyzers, we inves- tigated the practical application of ampouled phosphate- bicarbonate-thioride solutions tonometered with mixtwes of carbon dioxide, oxygen, and nitrogen.This system offers three discrete sets of pH, p02, Po2 values, which are consistent with normal and pathophysiologicaily high and low values. The stated values were

A. H. J. Maas; A. H. Veefklnd; R. A. M. Van den Camp; A. J. Teunissen; E. K. A. Winckers; A. P. Jansen

231

Optimal trellis-based buffered compression and fast approximations  

Microsoft Academic Search

The authors formalize the description of the buffer-constrained adaptive quantization problem. For a given set of admissible quantizers used to code a discrete nonstationary signal sequence in a buffer-constrained environment, they formulate the optimal solution. They also develop slightly suboptimal but much faster approximations. These solutions are valid for any globally minimum distortion criterion, which is additive over the individual

Antonio Ortega; Kannan Ramchandran; Martin Vetterli

1994-01-01

232

Ring Buffered Network Bus.  

National Technical Information Service (NTIS)

This report describes the research effort to demonstrate the integration of a data sharing technology, Ring Buffered Network Bus, in development by Dryden Flight Research Center, with an engine simulation application, the Java Gas Turbine Simulator, in de...

1997-01-01

233

Coastal Wetlands Buffer Delineation.  

National Technical Information Service (NTIS)

The New Jersey Coastal Management Program requires that development in the coastal zone incorporate a buffer to protect environmentally sensitive areas such as wetlands. The objectives of the present investigation were (a) to measure the levels of direct ...

J. K. Shisler R. A. Jordan R. N. Wargo

1987-01-01

234

A buffer diverter system  

NASA Astrophysics Data System (ADS)

The prevention of sympathetic detonations between donor and acceptor bombs, which are stored lying horizontally lying parallel to each other, is accomplished using a buffer diverter system. One example of a buffer diverter system is a pair of molded concrete bases, each supporting a horizontal bomb and conforming to the shape of its respective bomb up to its horizontal centerline. In the first example, the entire space between the two molded concrete bases and bombs is filled in with a buffer which has sufficient width to attenuate the shock of detonation down pressure levels below a pressure threshold needed to induce an acceptor bomb to sympathetically detonate. In another example of a buffer diverter system, the buffer is replaced with a diverter. The diverter is an I-beam which abuts each bomb at its horizontal centerline and runs the length of the two bombs. The I-beam has the same width as the buffer, but its surface area presented to each bomb is nearly the minimum required to deflect fragments from the silhouette of the acceptor bomb.

Foster, J. C., Jr.

1985-07-01

235

StackGuard: Automatic Adaptive Detection and Prevention of Buffer-Overflow Attacks  

Microsoft Academic Search

This paper presents a systematic solution to the per- sistent problem of buffer overflow attacks. Buffer over- flow attacks gained notoriety in 1988 as part of the Morris Worm incident on the Internet. While it is fairly simple to fix individual buffer overflow vulnerabilities, buffer overflow attacks continue to this day. Hundreds of at- tacks have been discovered, and while

Crispin Cowan; Calton Pu; Dave Maier; Heather Hinton; Jonathan Walpole; Peat Bakke; Steve Beattie; Aaron Grier; Perry Wagle; Qian Zhang

236

StackGuard: Automatic Adaptive Detection and Prevention of Buffer-Overflow Attacks  

Microsoft Academic Search

This paper presents a systematic solution to the persistent problem of buffer overflow attacks. Buffer overflow attacks gained notoriety in 1988 as part of the Morris Worm incident on the Internet. While it is fairly simple to fix individual buffer overflow vulnerabilities, buffer overflow attacks continue to this day. Hundreds of attacks have been discovered, and while most of the

Crispin Cowan; Calton Pu; Dave Maier; Heather Hinton; Jonathan Walpole

1998-01-01

237

Growth and Nutrient Uptake by Barley (Hordeum vulgare L. cv Herta): Studies Using an N-(2-Hydroxyethyl)ethylenedinitrilotriacetic Acid-Buffered Nutrient Solution Technique (II. Role of Zinc in the Uptake and Root Leakage of Mineral Nutrients).  

PubMed Central

Barley seedlings (Hordeum vulgare L. cv Herta) were grown in N-(2-hydroxyethyl)ethylenedinitrilotriacetic acid-buffered nutrient solutions with or without adequate Zn supplies. Fifteen-d-old Zn-deficient seedlings contained higher concentrations of Mn, Ca, Mg, and P in their shoots and more Fe, Mn, Cu, K, Ca, and P in their roots than did similar Zn-adequate seedlings, confirming results reported in our companion study (W.A. Norvell and R.M. Welch [1993] Plant Physiol 101: 619-625). Zn-deficient roots leaked greater quantities of K, Mn, Cu, and Cl than did roots supplied adequately with Zn; they also leaked significant amounts of Zn even though the seedlings were not supplied Zn during growth. Calculated uptake rates of P, Mn, and Na were sharply reduced, but uptake rates of K and Mg were stimulated by increasing the Zn2+ activity in nutrient solutions. Intact roots of Zn-deficient seedlings contained lower concentrations of 5,5[prime] -dithio-bis(2-nitrobenzoic acid) reactive sulfhydryl groups in comparison to Zn-adequate roots. Apparently, Zn is required for the uptake and retention of several mineral nutrients by roots, possibly by playing a protective role in preventing the oxidation of sulfhydryl groups to disulfides in root-cell plasma membrane proteins involved in ion channel-gating phenomena.

Welch, R. M.; Norvell, W. A.

1993-01-01

238

Isotherm parameters and intraparticle mass transfer kinetics on molecularly imprinted polymers in acetonitrile/buffer mobile phases  

SciTech Connect

The equilibrium isotherm and the intraparticle mass transfer kinetics of the enantiomers of the template were investigated on an Fmoc-L-tryptophan (Fmoc-L-Trp) imprinted polymer at different pHs and water concentrations in acetonitrile/aqueous buffer mobile phases. The equilibrium isotherm data were measured using frontal analysis at 25 {+-} 2 C. The adsorption energy distribution was found to be trimodal, with narrow modes. Consistent with this distribution, the adsorption data were modeled using a tri-Langmuir isotherm equation and the best estimates of the isotherm parameters were determined. The intraparticle mass transfer parameters were derived by comparing the profiles of experimental overloaded bands and the profiles calculated using the isotherm model and the lumped pore diffusion (POR) model of chromatography. These results showed that different adsorption and mass transfer mechanisms exist in mobile phases made of acetonitrile/aqueous buffer and of acetonitrile/acetic acid solutions.

Kim, Hyunjung [University of Tennessee, Knoxville (UTK); Kaczmarski, Krzysztof [University of Tennessee and Rzeszow University of Technology, Poland; Guiochon, Georges A [ORNL

2006-03-01

239

The SVT Hit Buffer  

SciTech Connect

The Hit Buffer is part of the Silicon Vertex Tracker, a trigger processor dedicated to the reconstruction of particle trajectories in the Silicon Vertex Detector and the Central Tracking Chamber of the Collider Detector at Fermilab. The Hit Buffer is a high speed data-traffic node, where thousands of words are received in arbitrary order and simultaneously organized in an internal structured data base, to be later promptly retrieved and delivered in response to specific requests. The Hit Buffer is capable of processing data at a rate of 25 MHz, thanks to the use of special fast devices like Cache-Tag RAMs and high performance Erasable Programmable Logic Devices from the XILINX XC7300 family.

Belforte, S.; Dell`Orso, M.; Donati, S. [I.N.F.N., Pisa (Italy)] [and others

1996-06-01

240

A Multiaccess Frame Buffer Architecture  

Microsoft Academic Search

Many current graphical display systems are based around a memory array commonly known as a frame buffer. In these systems, the frame buffer contains the array of pixels currently being displayed. Updates to the display are accomplished by modifying the values in the frame buffer. The author demonstrates how the performance of frame buffer based systems can be improved by

David T. Harper III

1994-01-01

241

Coprecipitation of Pu(IV) with Fe(III) and Cr(III) hydroxides from nitrate-acetate solutions under hydrothermal conditions simulating deep disposal of liquid radioactive wastes  

Microsoft Academic Search

Precipitation of Fe(III), Cr(III), Ni(II), and Mn(II) from nitrate-acetate solutions and coprecipitation of Pu(IV) with Fe(III)\\u000a and Cr(III) were studied. The degree of precipitation of 80–95% is attained for Fe(III) at 95–200C and pH>0.5–0.6, and for\\u000a Cr(III), at T=95C and pH?4.0 or T=200C and pH?1.0. The phase composition of the precipitates formed by thermal hydrolysis of iron nitrate in model

I. M. Kosareva; M. K. Savushkina; A. B. Yusov; A. M. Fedoseev; O. V. Isakova; V. A. Boldyrev; V. I. Mishkevich

2006-01-01

242

Buffering as a means for increasing growth and butanol production by Clostridium acetobutylicum  

Microsoft Academic Search

Summary The objective of this work was to optimize butanol formation in the acetone-butanol-ethanol (ABE) fermentation by examining the level of buffering as it affects the dissociation of butyric acid to the less toxic butyrate anion. Experiments were carried out in batch culture using chemically defined (P2) or complex media containing various buffering agents. These included salts of acetate, citrate,

Dennis L. Bryant; Hans P. Blaschek

1988-01-01

243

Epitaxial growth and thermal dynamics of CeO2 buffer layer on textured Ni-W substrates for YBCO coated conductors  

NASA Astrophysics Data System (ADS)

In present study, the biaxially textured CeO2 buffer layers on Ni-W substrates have been prepared by chemical solution deposition (CSD) with cerium acetate as the starting precursor, mixed with solvents of Propionic acid, Isopropanol and Acetylacetone. Typical XRD ?-2? scans and the pole figure display well out-of-plane and in-plane textures of CeO2 films. SEM and AFM results suggest that the buffer layer have uniform and smooth surface. Meanwhile, the effects of heating rate on CeO2 formation starting from the precursor solution have been studied using differential thermal analysis (DTA). And the further analysis is given by XRD results for precursor xrogel at the corresponding temperature. Detailed high temperature optical microscope (HTOM) photographs investigate the surface characteristics evolved with temperature.

Pan, C. Y.; Cai, C. B.; Ying, L. L.; Lu, Y. M.; Liu, Z. Y.; Gao, B.; Liu, J. L.

2008-03-01

244

Recovery of very dilute acetic acid using ion exchange  

SciTech Connect

Acetic and related acids occur in many industrial wastewaters, often mixed with several other classes of organic compounds. Acetic acid can be recovered from 1% solutions using weakly basic ion exchange resins. The acid is adsorbed by the free-base form of the resin, which can then be eluted using a slurry of lime to give a solution of calcium acetate. This solution could either be evaporated to crystallize calcium acetate or reacted with sulfuric acid to form acetic acid and gypsum. Laboratory tests of the proposed process gave product solutions of 15--20% acetic acid using pure 1% acetic acid as feed. Some measurements using a typical industrial effluent gave similar recoveries and showed that there was no initial fouling of the resins.

Cloete, F.L.D.; Marais, A.P. [Univ. of Stellenbosch (South Africa). Dept. of Chemical Engineering

1995-07-01

245

Optimization of protein solution by a novel experimental design method using thermodynamic properties.  

PubMed

In this study, the structural stability of hen egg white lysozyme in solution at various pH levels and in different types of buffers, including acetate, phosphate, histidine, and Tris, was investigated by means of differential scanning calorimetry (DSC). Reasonable pH values were selected from the buffer ranges and were analyzed statistically through design of experiment (DoE). Four factors were used to characterize the thermograms: calorimetric enthalpy (?H), temperature at maximum heat flux (T( m )), van't Hoff enthalpy (?H( V )), and apparent activation energy of protein solution (E(app)). It was possible to calculate E(app) through mathematical elaboration from the Lumry-Eyring model by changing the scan rate. The transition temperature of protein solution, T( m ), increased when the scan rate was faster. When comparing the T( m ), ?H( V ), ?H, and E(app) of lysozyme in various pH ranges and buffers with different priorities, lysozyme in acetate buffer at pH 4.767 (scenario 9) to pH 4.969 (scenario 11) exhibited the highest thermodynamic stability. Through this experiment, we found a significant difference in the thermal stability of lysozyme in various pH ranges and buffers and also a new approach to investigate the physical stability of protein by DoE. PMID:23054718

Kim, Nam Ah; An, In Bok; Lee, Sang Yeol; Park, Eun-Seok; Jeong, Seong Hoon

2012-10-09

246

Delignification of Bagasse with Acetic Acid and Ozone. Part 1. Acetic Acid Pulping  

Microsoft Academic Search

Two-stage delignification of sugarcane bagasse with acetic acid and ozone was investigated. The better pulp was obtained pulping bagasse in aqueous solution of acetic acid (80% volume) at 145°C during 60 min. The liquor\\/bagasse ratio (L\\/B) was 10:1 and the kappa number was 44; it fell to 10 in the ozone stage due to selectivity of acetic acid medium. Pulp

H. Contreras Q; Z. A. Nagieb; R. Sanjuán D

1997-01-01

247

Virginia Tech - Buffer Pool  

NSDL National Science Digital Library

Allows user to select from FIFO, LRU, and LFU page replacement strategies. User then gives a series of page requests and the AV shows the decisions made regarding page replacement. Simple to use, clearly shows the process. It would be nice if the user could pick the size of the backing memory and the buffer pool. Recommended as lecture aide, standalone, self-study suppliment to tutorial or lecture.

Shaffer, Cliff; Sariaya, Purvi

248

Simultaneous routing and buffer insertion with restrictions on buffer locations  

Microsoft Academic Search

During the routing of global interconnects, macro blocks formuseful routing regions which allow wires to go through but forbidbuffers to be inserted. They give restrictions on bufferlocations. In this paper, we take these buffer location restrictionsinto consideration and solve the simultaneous mazerouting and buffer insertion problem. Given a block placementdefining buffer location restrictions and a pair of pins(a source and

Hai Zhou; D. F. Wong; I-Min Liu; Adnan Aziz

1999-01-01

249

Buffer Capacity of a Polyprotic Acid: First Derivative of the Buffer Capacity and pKa Values of Single and Overlapping Equilibria  

Microsoft Academic Search

Buffer capacity appears in a variety of fields, and its approximate calculation is of practical importance for the design of new buffer solutions, being also a quantity related to titrations. The aims of this paper are (i) to devise simple expressions for the buffer capacity and its first derivative for a polyprotic acid, which may be easily extended to a

Agustin G. Asuero

2007-01-01

250

RED Facts: Tridecenyl Acetates.  

National Technical Information Service (NTIS)

This fact sheet summarizes the information in the RED document for reregistration case 4116, tridecenyl acetates. Tridecenyl acetates are sex attractant pheromones used in tomato fields to disrupt the mating behavior of tomato pinworms.

1996-01-01

251

Coordination of Lanthanide Acetates  

SciTech Connect

A study of the structures of hydrated and anhydrous lanthanide acetates by X-ray diffraction, infrared spectra, and absorption spectra demonstrates that there are three separate structures for hydrated lanthanide acetates and four structures for anhydrous acetates. This paper discusses the results of that study.

Karraker, D.G.

2001-08-29

252

Principles of database buffer management  

Microsoft Academic Search

This paper discusses the implementation of a database buffer manager as a component of a DBMS. The interface between calling components of higher system layers and the buffer manager is described; the principal differences between virtual memory paging and database buffer management are outlined; the notion of referencing versus addressing of database pages is introduced; and the concept of fixing

Wolfgang Effelsberg; Theo Haerder

1984-01-01

253

Effect of buffer and pH on growth and protein content of carrot ( Daucus carota L.) in liquid shake culture  

Microsoft Academic Search

Phosphate, succinate, acetate and maleate buffers were tested for buffering B5 liquid medium. Phosphate (0·02 M) and acetate (0·002 M) were the most suitable buffers as they promoted dry weight accumulation\\u000a and nitrogen assimilation, they also exhibited less change in pH after 5 days cultivation of carrot cells. The pH increase\\u000a from 5·5 up to 6·5 also increased the dry

R P SINGIK; B D Singh; R B Singh

1981-01-01

254

Comments on the determination of isoenzyme polymorphism (ADA, AK, 6-PGD, PGM) by cellulose acetate electrophoresis  

Microsoft Academic Search

Summary The paper highlights certain peculiarities of isoenzyme polymorphism as determined by cellulose acetate electrophoresis, as compared to other supporting media at different pH levels and concentrations of the buffer.

H.-H. Sonneborn

1972-01-01

255

Liquid Chromatography-Tandem Mass Spectrometry for Analysis of Intestinal Permeability of Loperamide in Physiological Buffer  

PubMed Central

Analysis of in vitro samples with high salt concentrations represents a major challenge for fast and specific quantification with liquid chromatography-tandem mass spectrometry (LC-MS/MS). To investigate the intestinal permeability of opioids in vitro employing the Ussing chamber technique, we developed and validated a fast, sensitive and selective method based on LC–MS/MS for the determination of loperamide in HEPES-buffered Ringer's solution. Chromatographic separation was achieved with an Atlantis dC18 column, 2.1 mm×20 mm, 3 µm particle size and a gradient consisting of methanol/0.1% formic acid and ammonium acetate. The flow rate was 0.7 ml/min, and the total run time was 3 min. For quantification, two mass transitions for loperamide and a deuterated internal standard (methadone-d3) were used. The lower limit of loperamide quantification was 0.2 ng/ml. This new LC-MS/MS method can be used for the detection of loperamide in any experimental setup using HEPES-buffered Ringer's solution as a matrix compound.

Rubelt, Miriam S.; Amasheh, Salah; Grobosch, Thomas; Stein, Christoph

2012-01-01

256

Buffer Energy Nuclear Fusion  

NASA Astrophysics Data System (ADS)

A compact scheme of non-thermonuclear fusion is presented. Hydrogen ions are implanted directly from nonthermal discharge plasma or ion source into a surface of liquid Li metal at a buffer energy of a few tens keV where nuclear stopping occurs. The ions interact with Li atoms or mixed element atoms which are not being internally excited and tend towards the formation of united atoms at the minimum Gibbs free energy point. This leads to the enhanced rate of non-thermonuclear fusion of hydrogen ions due to cohesion in the liquid metal.

Ikegami, Hidetsugu

2001-10-01

257

Highly textured La 2 Zr 2 O 7 and CeO 2 buffer layers by ink jet printing for coated conductors  

Microsoft Academic Search

The objective of this paper is to prove the possibility to produce single side buffered substrates for coated conductors.\\u000a We report for the first time the production of highly textured NiW\\/La2Zr2O7\\/CeO2 system by all-chemical solution deposition means using an in-house built drop-on-demand ink-jet printer. Lanthanum zirconate\\u000a precursor ink was produced using lanthanum acetate and zirconium n-propoxide modified with propionic and

M. C. Cordero-Cabrera; T. Mouganie; B. A. Glowacki; M. Bäcker; M. Falter; B. Holzapfel; J. Engell

2007-01-01

258

Single-biomolecule observation with micro one-way valves for rapid buffer exchange  

NASA Astrophysics Data System (ADS)

This paper describes a method for the rapid exchange of buffer solution during single-molecule observation. We use a simple, transparent, all-plastic one-way valve integrated on a coverslip on a flow cell. The valve is formed using a membrane made of parylene covering a microhole. It opens when a buffer solution is introduced from the microhole (the flow pushes the cover membrane) and closes when suctioning the buffer solution (the membrane is pulled back and seals the microhole to prevent the diffusion of the solution). To check valve performance, we observed the response of a rotary biomotor, F1-ATPase, for several buffer solutions in the fabricated chamber.

Hirono-Hara, Yoko; Noji, Hiroyuki; Takeuchi, Shoji

2009-05-01

259

Pallidol hexa-acetate ethyl acetate monosolvate  

PubMed Central

The entire mol­ecule of pallidol hexa­acetate {systematic name: (±)-(4bR,5R,9bR,10R)-5,10-bis­[4-(acet­yloxy)phen­yl]-4b,5,9b,10-tetra­hydro­indeno­[2,1-a]indene-1,3,6,8-tetrayl tetra­acetate} is completed by the application of twofold rotational symmetry in the title ethyl acetate solvate, C40H34O12·C4H8O2. The ethyl acetate mol­ecule was highly disordered and was treated with the SQUEEZE routine [Spek (2009 ?). Acta Cryst. D65, 148–155]; the crystallographic data take into account the presence of the solvent. In pallidol hexa­acetate, the dihedral angle between the fused five-membered rings (r.m.s. deviation = 0.100?Å) is 54.73?(6)°, indicating a significant fold in the mol­ecule. Significant twists between residues are also evident as seen in the dihedral angle of 80.70?(5)° between the five-membered ring and the pendent benzene ring to which it is attached. Similarly, the acetate residues are twisted with respect to the benzene ring to which they are attached [C—O(carb­oxy)—C—C torsion angles = ?70.24?(14), ?114.43?(10) and ?72.54?(13)°]. In the crystal, a three-dimensional architecture is sustained by C—H?O inter­actions which encompass channels in which the disordered ethyl acetate mol­ecules reside.

Mao, Qinyong; Taylor, Dennis K.; Ng, Seik Weng; Tiekink, Edward R. T.

2013-01-01

260

The quantitation of buffering action I. A formal & general approach  

PubMed Central

Background Although "buffering" as a homeostatic mechanism is a universal phenomenon, the quantitation of buffering action remains controversial and problematic. Major shortcomings are: lack of a buffering strength unit for some buffering phenomena, multiple and mutually incommensurable units for others, and lack of a genuine ratio scale for buffering strength. Here, I present a concept of buffering that overcomes these shortcomings. Theory Briefly, when, for instance, some "free" H+ ions are added to a solution (e.g. in the form of strong acid), buffering is said to be present when not all H+ ions remain "free" (i.e., bound to H2O), but some become "bound" (i.e., bound to molecules other than H2O). The greater the number of H+ ions that become "bound" in this process, the greater the buffering action. This number can be expressed in two ways: 1) With respect to the number of total free ions added as "buffering coefficient b", defined in differential form as b = d(bound)/d(total). This measure expresses buffering action from nil to complete by a dimensionless number between 0 and 1, analogous to probabilites. 2) With respect to the complementary number of added ions that remain free as "buffering ratio B", defined as the differential B = d(bound)/d(free). The buffering ratio B provides an absolute ratio scale, where buffering action from nil to perfect corresponds to dimensionless numbers between 0 and infinity, and where equal differences of buffering action result in equal intervals on the scale. Formulated in purely mathematical, axiomatic form, the concept reveals striking overlap with the mathematical concept of probability. However, the concept also allows one to devise simple physical models capable of visualizing buffered systems and their behavior in an exact yet intuitive way. Conclusion These two measures of buffering action can be generalized easily to any arbitrary quantity that partitions into two compartments or states, and are thus suited to serve as standard units for buffering action. Some exemplary treatments of classical and non-classical buffering phenomena are presented in the accompanying paper.

Schmitt, Bernhard M

2005-01-01

261

Buffered tungsten reference electrode for LWR applications  

SciTech Connect

An alternative reference electrode for electrochemical corrosion potential (ECP) measurements, consisting of tungsten metal in a saturated Ca(OH){sub 2} buffer solution, has been developed and tested under boiling water reactor (BWR) operating conditions as part of the Massachusetts Institute of Technology electric utility program research on coolant technology in support of light water reactor (LWR) operations. All major BWR vendors currently rely on internal Ag/AgCl reference electrodes for in-reactor ECP measurement. Although adequate performance has been achieved in normal water chemistry (NWC), their longevity is hampered by reduction of AgCl in hydrogen concentration. In summary, tungsten buffered by saturated Ca(OH){sub 2} solution appears to be a useful alternative reference electrode for use in LWR coolant. Further tests are planned, including characterization of the electrochemical reactions for this system. Development of a radiation-resistant version is also required.

Hwang, I.S.; Outwater, J.O.; Driscoll, M.J. (Massachusetts Inst. of Technology, Cambridge (United States))

1992-01-01

262

Provably good global buffering using an available buffer block plan  

Microsoft Academic Search

To implement high-performance global interconnect without impacting the performance of existing blocks, the use of buffer blocks is increasingly popular in structured-custom and block-based ASIC\\/SOC methodologies. Recent works by Cong et al. [6] and Tang and Wong [25] give algorithms to solve the buffer block planning problem. In this paper we address the problem of how to perform buffering of

Feodor F. Dragan; Andrew B. Kahng; Ion I. Mandoiu; Sudhakar Muddu; Alexander Zelikovsky

2000-01-01

263

Resonance Raman characterization of the different forms of ground-state 8-substituted 7-hydroxyquinoline caged acetate compounds in aqueous solutions.  

PubMed

To investigate the substituent effect on the distribution of the forms of the ground-state species of 8-substituted 7-hydroxyquinolines, ultraviolet-absorption and resonance Raman experiments were performed for 8-chloro-7-hydroxyquinoline (CHQ-OAc) and 8-cyano-7-hydroxyquinoline (CyHQ-OAc) in acetonitrile (MeCN), in NaOH-H(2)O/MeCN (60:40, v/v, pH 11-12), and in H(2)O/MeCN (60:40, v/v, pH 6-7) solutions, and these results were compared to those previously reported for the 8-bromo-7-hydroxyquinoline (BHQ-OAc) compound. Swapping a bromine atom in BHQ-OAc for a chlorine atom in CHQ-OAc causes the amount of the tautomeric species to become larger, although the neutral species is still the predominant species for both systems in water-rich solutions. The absorption spectra and the resonance Raman spectra of CyHQ-OAc suggest that, because of the strong electron-withdrawing nature of the cyano substituent, a measurable amount of the anionic species is present and the tautomeric species cannot be easily detected in water-rich solutions. The results reported here reveal large substituent effects on the distribution of the different forms of the XHQ-OAc compounds in largely aqueous solutions. The steric effect of the 8-substituted group and competitive hydrogen bonding between the 8-substituted group and water molecules hinders the formation of a cyclic BHQ-OAc-water complex, and the electron-withdrawing property of the 8-substituted group enhances the deprotonation of the phenol group while disfavoring the formation of the positively charged quinoline nitrogen. We briefly discuss the implications of the substituent effects for using these compounds as phototriggers. PMID:20113003

An, Hui-Ying; Ma, Chensheng; Li, Wen; Harris, Kyle T; Dore, Timothy M; Phillips, David Lee

2010-02-25

264

Buffering capacity of the chief components of nutritive media for algae  

Microsoft Academic Search

The buffering capacity of solutions of KH2PO4 and NaHCO3 increases with their concentration, the behaviour being describable by mathematical expressions. Solutions of KH2PO4 prepared from tap water exhibit a buffering capacity higher by an order of magnitude than those prepared from distilled water.\\u000a However, there is no difference between the buffering capacities of solutions of NaHCO3 prepared from tap and

K. Lívanský

1982-01-01

265

Application of solution deposition techniques to coated conductor fabrication  

NASA Astrophysics Data System (ADS)

Coated conductors offer a viable alternative to the BSCCO PIT tapes. However, at the current juncture, results are being reported for conductors with buffer layers and superconductor layers processed using conventional thin film deposition which are vacuum based. Also these conductors are fabricated using four or five buffer layers between the superconductor and the metal substrate. These aspects of the fabrication route drive the cost of the process to prohibitively high values. This work is directed at the development of fabrication routes for cube textured nickel substrates, and metallorganic decomposition (MOD) routes for buffer layers and Y123 layers using simple solution based techniques which can be readily scaled. Studies of cube texturing of nickel using rolling and recrystallization showed that it is possible to produce textured nickel substrates with a FWHM of 8--10°. The substrate quality of the nickel is determined by the purity of the cube texture and the cleanliness of the surface. Processing of oriented buffer layers of barium zirconate and strontium titanate using simple metal organic decomposition routes have been studied. These processes, which use precursor solutions made by dissolution of simple acetates in common solvents like acetic acid and methanol, produce highly oriented buffer layers even when processed in a partially reducing atmosphere. Therefore, these MOD routes for buffer layer processing are compatible with nickel substrates and produce buffer layers oriented as sharply as the underlying nickel substrate. Y123 processing using fluorinated precursors, as in the TFA process, effectively circumvents the BaCO3 problem associated with most MOD routes for Y123 processing. This route, under optimized process conditions, yields Y123 films with Jc of the order of 106 A/cm2 on single crystal substrates. Studies of the compatibility of the TFA process with the MOD buffer layers showed that current density of the order of 106 A/cm 2 can be obtained for Y123 on buffered single crystals. These results give promise to the applicability of these scaleable solution deposition techniques to coated conductor fabrication.

Sathyamurthy, Srivatsan

266

The Endogenous Calcium Buffer and the Time Course of Transducer Adaptation in Auditory Hair Cells  

Microsoft Academic Search

anism that is sensitive to the level of internal calcium buffer. We have used the properties of transducer adaptation to compare the effects of exogenous calcium buffers in the patch electrode solution with those of the endogenous buffer assayed with perforated-patch recording. The endogenous buffer of the hair bundle was equivalent to 0.1-0.4 mM BAPTA and, in a majority of

A. J. Ricci; R. Fettiplace

1998-01-01

267

On the delay analysis of a TDMA channel with finite buffer capacity  

NASA Astrophysics Data System (ADS)

The throughput performance of a TDMA channel with finite buffer capacity for transmitting data messages is considered. Each station has limited message buffer capacity and has Poisson message arrivals. Message arrivals will be blocked if the buffers are congested. Using the embedded Markov chain model, the solution procedure for the limiting system-size probabilities is presented in a recursive fashion. Numerical examples are given to demonstrate the tradeoffs between the blocking probabilities and the buffer sizing strategy.

Yan, T.-Y.

1982-08-01

268

New buffer pH method for rapid estimation of exchangeable acidity and lime requirement of soils  

Microsoft Academic Search

A new buffer pH method (BpH) for the rapid estimation of unbuffered salt?exchangeable acidity (ACe) and lime requirement (LR) has been developed. The buffer reagent, consisting of sodium glycerophosphate, acetic acid, trletlianolamine, ammonium chloride and barium chloride, was useful within the pH range 3.8 to 6.6. Delta values from BpH were converted into buffer pH acidity values (AC) and calibrated

A. Mehlich

1976-01-01

269

Acetate and Formate Stress: Opposite Responses in the Proteome of Escherichia coli  

Microsoft Academic Search

Acetate and formate are major fermentation products of Escherichia coli. Below pH 7, the balance shifts to lactate; an oversupply of acetate or formate retards growth. E. coli W3110 was grown with aeration in potassium-modified Luria broth buffered at pH 6.7 in the presence or absence of added acetate or formate, and the protein profiles were compared by two-dimensional sodium

CHRISTOPHER KIRKPATRICK; LISA M. MAURER; NIKKI E. OYELAKIN; YULIYA N. YONCHEVA; RUSSELL MAURER; JOAN L. SLONCZEWSKI

2001-01-01

270

Memory access buffering in multiprocessors  

Microsoft Academic Search

In highly-pipelined machines, instructions and data are prefetched and buffered in both the processor and the cache. This is done to reduce the average memory access latency and to take advantage of memory interleaving. Lock-up free caches are designed to avoid processor blocking on a cache miss. Write buffers are often included in a pipelined machine to avoid processor waiting

Michel Dubois; Christoph Scheurich; Faye A. Briggs

1986-01-01

271

Buffering in optical packet switches  

Microsoft Academic Search

This paper consists of a categorization of optical buffering strategies for optical packet switches, and a comparison of the performance of these strategies both with respect to packet loss\\/delay and bit error rate (BER) performance. Issues surrounding optical buffer implementation are discussed, and representative architectures are introduced under different categories. Conclusions are drawn about packet loss and BER performance, and

David K. Hunter; Meow C. Chia; Ivan Andonovic

1998-01-01

272

Aluminum speciation and equilibria in aqueous solution: V. Gibbsite solubility at 50[degrees]C and pH 3-9 in 0. 1 molal NaCl solutions (a general model for aluminum speciation; analytical methods)  

Microsoft Academic Search

This study reports 184 new measurements of the solubility of gibbsite at 50[degrees]C and 0.1 molal ionic strength in NaCl solutions of acetate, bistris, and tris buffers with hydrogen ion concentrations ranging from 10[sup [minus]3] to 10[sup [minus]9] molal. Samples collected at 35, 63, 66, 120, and 144 days show no detectable difference in the total aluminum at similar pH

D. J. Wesolowski; D. A. Palmer

1994-01-01

273

Aluminum speciation and equilibria in aqueous solution: V. Gibbsite solubility at 50°C and pH 3-9 in 0.1 molal NaCl solutions (a general model for aluminum speciation; analytical methods)  

Microsoft Academic Search

This study reports 184 new measurements of the solubility of gibbsite at 50°C and 0.1 molal ionic strength in NaCl solutions of acetate, bistris, and tris buffers with hydrogen ion concentrations ranging from 10 -3 to 10 -9 molal. Samples collected at 35, 63, 66, 120 and 144 days show no detectable difference in the total aluminum at similar pH

David J. Wesolowski; Donald A. Palmer

1994-01-01

274

Aluminum speciation and equilibria in aqueous solution: V. Gibbsite solubility at 50[degrees]C and pH 3-9 in 0. 1 molal NaCl solutions (a general model for aluminum speciation; analytical methods)  

SciTech Connect

This study reports 184 new measurements of the solubility of gibbsite at 50[degrees]C and 0.1 molal ionic strength in NaCl solutions of acetate, bistris, and tris buffers with hydrogen ion concentrations ranging from 10[sup [minus]3] to 10[sup [minus]9] molal. Samples collected at 35, 63, 66, 120, and 144 days show no detectable difference in the total aluminum at similar pH values. Correction of the measured solubilities for complexation reactions involving Al[sup 3+] with acetate and Al(OH)[sub 4][sup [minus

Wesolowski, D.J.; Palmer, D.A. (Oak Ridge National Lab., TN (United States))

1994-07-01

275

Effect of light and heat on the stability of montelukast in solution and in its solid state  

Microsoft Academic Search

The chemical stability of montelukast (Monte) in solution and in its solid state was studied. A simultaneous measurement of Monte and its degradation products was determined using a selective HPLC method. The HPLC system comprised a reversed phase column (C18) as the stationary phase and a mixture of ammonium acetate buffer of pH 3.5 and methanol (15:85v\\/v) as the mobile

Mahmoud M. Al Omari; Rufaida M. Zoubi; Enas I. Hasan; Tariq Z. Khader; Adnan A. Badwan

2007-01-01

276

[Degradation of oxytetracycline with ozonation in acetic acid solvent].  

PubMed

Use acetic acid as the media of ozone degradation of oxytetracycline (OTC), and effects of the initial dosing ratio of ozone/OTC, ozone flow, free radical scavenger, metal ions on the removal rate of OTC were investigated respectively. The results showed that acetic acid had a high ozone stability and solubility. OTC had a high removal rate and degradation rate in acetic acid solution. With the increase of OTC dosage, the removal rate of OTC decreased in acetic acid. Removal rate of OTC was increased distinctly when ozone flow increased properly. It was also observed that free radical scavenger had a significantly negative effect on OTC ozonation degradation in acetic acid. Furthermore the main reactions of OTC ozone oxidation were direct oxidation and indirect oxidation in acetic acid. When Fe3+ and Co2+ were existent in acetic acid, the degradation of OTC was inhibited significantly. PMID:23379161

Li, Shi-Yin; Li, Xiao-Rong; Zhu, Yi-Ping; Zhu, Jiang-Peng; Wang, Guo-Xiang

2012-12-01

277

Facilitation through Buffer Saturation: Constraints on Endogenous Buffering Properties  

PubMed Central

Synaptic facilitation (SF) is a ubiquitous form of short-term plasticity, regulating synaptic dynamics on fast timescales. Although SF is known to depend on the presynaptic accumulation of Ca2+, its precise mechanism is still under debate. Recently it has been shown that at certain central synapses SF results at least in part from the progressive saturation of an endogenous Ca2+ buffer (Blatow et al., 2003), as proposed by Klingauf and Neher (1997). Using computer simulations, we study the magnitude of SF that can be achieved by a buffer saturation mechanism (BSM), and explore its dependence on the endogenous buffering properties. We find that a high SF magnitude can be obtained either by a global saturation of a highly mobile buffer in the entire presynaptic terminal, or a local saturation of a completely immobilized buffer. A characteristic feature of BSM in both cases is that SF magnitude depends nonmonotonically on the buffer concentration. In agreement with results of Blatow et al. (2003), we find that SF grows with increasing distance from the Ca2+ channel cluster, and increases with increasing external Ca2+, [Ca2+]ext, for small levels of [Ca2+]ext. We compare our modeling results with the experimental properties of SF at the crayfish neuromuscular junction, and find that the saturation of an endogenous mobile buffer can explain the observed SF magnitude and its supralinear accumulation time course. However, we show that the BSM predicts slowing of the SF decay rate in the presence of exogenous Ca2+ buffers, contrary to experimental observations at the crayfish neuromuscular junction. Further modeling and data are required to resolve this aspect of the BSM.

Matveev, Victor; Zucker, Robert S.; Sherman, Arthur

2004-01-01

278

The intrinsic intracellular H+ buffering power of snail neurones.  

PubMed

1. We measured intracellular pH (pHi) in snail neurones using pH-sensitive glass microelectrodes. We then calculated the intracellular buffering power (beta i) from the pHi changes associated with the influx or efflux of a variety of weak acids or bases. 2. The weak acid anions butyrate and propionate (20 mM) gave similar values for beta i but those measured using 20 mM-acetate were on average twice as great. 3. Although solutions were nominally CO2-free, blockage of pHi regulation with SITS (4-acetamido-4'-isothiocyanatostilbene-2,2'-disulphonic acid) increased the sizes of the pHi changes upon weak acid addition and removal. The corresponding measured values of beta i were on average 26% lower with SITS than without. 4. With pHi regulation blocked, the use of 2.7% CO2 to measure beta i gave beta i values similar to those measured with butyrate or propionate. These values were about 50% less than those previously measured in snail neurones using CO2. 5. beta i values calculated from the pHi changes due to the removal of 5 mM of the weak bases trimethylamine, procaine and NH4Cl were all similar and comparable to those measured using butyrate or propionate. Removing the influence of pHi regulation on the undershoots after NH4Cl removal was found to decrease the apparent measured values of beta i by 10%. 6. Combining all the data (except the values obtained using CO2 and acetate), and adjusting for the errors due to pHi regulation reducing the sizes of the pHi changes, we found that the mean value for beta i was 10.4 +/- 0.6 mM (+/- S.E.M.) at a mean pHi of 7.36 +/- 0.05. 7. We also investigated the relationship between beta i and pHi using ionophoretic acid injection. By means of step-wise injections, with pHi regulation blocked, we found that at normal pHi levels beta i remained relatively constant. However, at a pHi of less than about 6.8 beta i increased with decreasing pHi. PMID:2585301

Szatkowski, M S; Thomas, R C

1989-02-01

279

Comparative study of recovering acetic acid with energy integrated schemes  

Microsoft Academic Search

The heat pumping and multi-effect distillation techniques were evaluated for recovering acetic acid from aqueous solutions with low boiling solvents, methyl tert-butyl ether (MTBE) and ethyl acetate (EtOAc). The overhead vapour recompression and two types of column cascading techniques are compared to the conventional acetic acid recovery scheme. It was found that (1) by switching the solvent to MTBE, approximately

S. Kürüm; Z. Fonyo

1996-01-01

280

Acetals and Ketals.  

National Technical Information Service (NTIS)

Thirteen open-chain simple cyclic and spirocyclic acetals and ketals were studied. The synthesis of all the cyclic compounds was accomplished by an alcoholysis reaction. The infrared and proton magnetic resonance spectra were measured and correlated. (Aut...

J. Radell R. E. Rondeau

1970-01-01

281

A gradient technique for general buffer storage design in a production line  

Microsoft Academic Search

In this paper, we present a complete and novel solution to the well known buffer storage design problem in a serial production line. The key ingredient of the solution is the efficient calculation of the gradient vector of the throughput with respect to the various buffer sizes. Analytical and experimental results are presented.

Y. C. HO; M. A. EYLER; T. T. CHIEN

1979-01-01

282

The Use of Polymeric Gels to Reduce Compaction in Cellulose Acetate Reverse Osmosis Membranes.  

National Technical Information Service (NTIS)

Polymeric gels were synthesized by crosslinking cellulose acetate in emulsion and solution reactions. These gels were used to replace a portion of the linear cellulose acetate in a standard Manjikian-type asymmetric membrane, with the aim of reducing long...

S. L. Rosen C. Irani L. Baayens

1972-01-01

283

21 CFR 520.1696a - Buffered penicillin powder, penicillin powder with buffered aqueous diluent.  

Code of Federal Regulations, 2010 CFR

...2009-04-01 2009-04-01 false Buffered penicillin powder, penicillin powder with buffered aqueous diluent. 520...FORM NEW ANIMAL DRUGS § 520.1696a Buffered penicillin powder, penicillin powder with buffered...

2009-04-01

284

Hierarchical Z-buffer visibility  

Microsoft Academic Search

An ideal visibility algorithm should a) quickly reject most of thehidden geometry in a model and b) exploit the spatial and perhapstemporal coherence of the images being generated. Ray castingwith spatial subdivision does well on criterion (a), but poorly oncriterion (b). Traditional Z-buffer scan conversion does well oncriterion (b), but poorly on criterion (a). Here we present a hierarchicalZ-buffer scan-conversion

Ned Greene; Michael Kass; Gavin S. P. Miller

1993-01-01

285

Organic electroluminescent devices with polymer buffer layer  

NASA Astrophysics Data System (ADS)

12 We have developed a new type of polymers having TPD unit combined with non-conjugated spacer group, poly(arylene ether sulfone)-containing and poly(arylene ether ketone)- containing tetraphenylbenzidine (PTPDES an PTPDEK) and also polymers with directly coupled triphenyl amine units (PPBA). When these polymers are mixed with strong acceptor such as TBPAH or DDQ, they indicated higher conductivity and facilitated hole injection from ITO to the hole transport layer. Spin-coating of such polymer from an organic solution on ITO was found to improve the surface roughness of ITO, resulting in reduced defects that cause electric short circuit between ITO and cathode. These buffer materials lowered the operation voltage and improved the thermal stability of the device. After storage of 1,000 hours at 85 degrees Celsius, the device with polymer buffer showed no degradation in luminance and small increase of operation voltage. In comparison with CuPc buffer, it is clear that the doped polymer is superior in terms of both efficiency and thermal stability.

Sato, Yoshiharu; Ogata, Tomoyuki; Kido, Junji

2001-02-01

286

Highly conductive composites of polyaniline with plasticized cellulose acetate  

Microsoft Academic Search

Highly transparent, conductive blends can be prepared from plasticized cellulose acetate and polyaniline protonated with sulphonic acids, phosphonic acids and phosphoric acid diesters. Films cast from m-cresol solution exhibit percolation threshold below 0.5 wt% and excellent mechanical properties of plasticized cellulose acetate.

A. Pro?; M. Zagorska; Y. Nicolau; F. Genoud; M. Nechtschein

1997-01-01

287

Protein Buffering in Model Systems and in Whole Human Saliva  

PubMed Central

The aim of this study was to quantify the buffer attributes (value, power, range and optimum) of two model systems for whole human resting saliva, the purified proteins from whole human resting saliva and single proteins. Two model systems, the first containing amyloglucosidase and lysozyme, and the second containing amyloglucosidase and ?-amylase, were shown to provide, in combination with hydrogencarbonate and di-hydrogenphosphate, almost identical buffer attributes as whole human resting saliva. It was further demonstrated that changes in the protein concentration as small as 0.1% may change the buffer value of a buffer solution up to 15 times. Additionally, it was shown that there was a protein concentration change in the same range (0.16%) between saliva samples collected at the time periods of 13:00 and others collected at 9:00 am and 17:00. The mode of the protein expression changed between these samples corresponded to the change in basic buffer power and the change of the buffer value at pH 6.7. Finally, SDS Page and Ruthenium II tris (bathophenantroline disulfonate) staining unveiled a constant protein expression in all samples except for one 50 kDa protein band. As the change in the expression pattern of that 50 kDa protein band corresponded to the change in basic buffer power and the buffer value at pH 6.7, it was reasonable to conclude that this 50 kDa protein band may contain the protein(s) belonging to the protein buffer system of human saliva.

Lamanda, Andreas; Cheaib, Zeinab; Turgut, Melek Dilek; Lussi, Adrian

2007-01-01

288

Thermal decomposition of acetate: III. Catalysis by mineral surfaces  

SciTech Connect

The kinetics of thermal decarboxylation of aqueous solutions of acetic acid and sodium acetate were evaluated at 335 and 355[degrees]C in contact with various surfaces as potential catalysts. Quartz, fused quartz, calcite, natural pyrite, titanium oxide, and Au apparently do not catalyze aqueous decarboxylation reactions, in contrast to Pyrex, Ca-montmorillonite, Fe-bearing montmorillonite, hematite, synthetic pyrite, and magnetite. The dependence of the rate of acetic acid decarboxylation on the surface area of pyrite per unit solution volume was also studied. The results show that the decarboxylation of acetic acid and acetate is catalyzed heterogeneously, with the cleavage of the C-C bond occurring while the acetate molecule is adsorbed onto a surface. Entropies and enthalpies of activation obtained from these experiments are compatible with the isokinetic relationship established previously for acetic acid and acetate under similar experimental conditions, indicating the existence of a common rate-determining step. Experimental evidence indicates that oxidation of acetic acid can occur with hematite and defected magnetite. These oxidative decomposition reactions differ from the decarboxylation reaction in that CO[sub 2] and polycondensates are produced instead of CO[sub 2] and CH[sub 4].

Bell, J.L.S.; Barnes, H.L. (Oak Ridge National Lab., TN (United States)); Palmer, D.A.; Drummond, S.E. (Pennsylvania State Univ., University Park, PA (United States))

1994-10-01

289

Observation of a combined dilution and salting effect in buffers under conditions of high dilution and high ionic strength  

Microsoft Academic Search

The pH value of buffer solutions is crucially dependent on the relative concentrations of all species in solution. The addition of water or neutral salt can have a significant effect on the pH of a buffer solution. This study examines the magnitude of the \\

Richard J. C. Brown; Martin J. T. Milton

2003-01-01

290

Establishing conservation buffers using precision information  

Microsoft Academic Search

Conservation buffers, such as filter strips and riparian forest buffers, are widely prescribed to improve and protect water quality in agricultural landscapes. These buffers intercept field runoff and retain some of its pollutant load before it reaches a waterway. A buffer typically is designed to have uniform width along a field margin and to intercept runoff that flows uniformly to

M. G. Dosskey; D. E. Eisenhauer; M. J. Helmers

291

Improving Water Quality With Conservation Buffers  

Microsoft Academic Search

Conservation buffer technologies are new approaches that need wider application. In-field buffer practices work best when used in combination with other buffer types and other conservation practices. Vegetative barriers may be used in combination with edge-of-field buffers to protect and improve their function and longevity by dispersing runoff and encouraging sediment deposition upslope of the buffer. It's important to understand

R. Lowrance; S. Dabney; R. Schultz

2003-01-01

292

Buffer Capacity in Aquatic Ecosystems.  

National Technical Information Service (NTIS)

Stream water quality and ecological balance can be substantially affected by pH changes. The change in the pH that one would otherwise expect to be induced by the influx of acidic or alkaline wastes can be significantly reduced by the buffering action of ...

F. G. Pohland W. R. Bolton

1974-01-01

293

Buffering New Information during Reading.  

ERIC Educational Resources Information Center

Describes two subject-paced reading experiments in which word-reading times were collected using the moving-window method. Finds that reading times of content words increase more steeply than reading times for function words. Discusses results in terms of buffer models of reading, the processing of different lexical classes, and hypotheses which…

Haberlandt, Karl; Graesser, Arthur C.

1989-01-01

294

Distributed communication via global buffer  

Microsoft Academic Search

Design and implementation of an inter-address-space communication mechanism for the SBN network computer are described. SBN's basic communication primitives appear in context of a new distributed systems programming language strongly supported by the network communication kernel. A model in which all communication takes place via a distributed global buffer results in simplicity, generality and power in the communication primitives. Implementation

David Gelernter; Arthur J. Bernstein

1982-01-01

295

[Buffer capacity of polyproton substances].  

PubMed

Mathematical analysis of protolytic properties of a polyelectrolite with arbitrary set of stepwise dissotiation constants is carried out, based on disintegration of summary titration curves and buffer capacity for basic functions. It is demonstrated, that in some cases (for example, investigation of biomembranes and their components) simplified disintegration variants can be used. Buffer titration curve of biopolymers and biomembranes is a "buffer spectrum", the position of bands on the pH scale, their intensity and half-width being determined by the nature of the object (the quantity and quality of hydrophilic groups and the set of its conformation states). Sharp peaks of the buffer spectrum correspond to the conformation transition of the object, and their half-width on the pH scale determines the cooperative degree of each conformation transition. The mathematical analysis described is not specific to the formation of polyprotonic complex, and it can be used in investigation of the complex formation with any monodentant ligand. It is concluded that the method described can be used in the investigation of complex biomembranes and different processes, in which these membranes participate. PMID:32925

Opanasenko, V K; Gerts, S M; Makarov, A D

1978-08-01

296

Water in polymer membranes. 4. Raman scattering from cellulose acetate films  

Microsoft Academic Search

Raman scattering was observed from thin film optical waveguides of cellulose acetate exposed to water vapor from 0% to 100% relative humidity (RH), and from dilute solutions of water in methyl acetate. Spectra of cellulose acetate (CA398, 39.8% acetyl) at low RH and cellulose triacetate (CTA) at low and high RH are consistent with the presence of water monomers that

J. R. Scherer; G. F. Bailey; S. Kint; R. Young; D. P. Malladi; B. Bolton

1985-01-01

297

Acid Rain Experiments: Observing Buffers in Lakes, Ponds, and Streams  

NSDL National Science Digital Library

In this experiment, students will observe the buffering effects of limestone on the acidity of water. They will prepare two containers of vinegar solution, place crushed limestone in one, and check the pH of the solution in each container periodically for six days, recording their mesurements. The experiment helps reinforce the idea that natural limestone occurring in lake bottoms or soil may help neutralize the effects of acid rain.

298

Oxime Acetates: Substrates for Acetylcholinesterase.  

National Technical Information Service (NTIS)

Oxime acetates function as typical substrates for acetylcholinesterase (AChE). Both syn 3- and syn 4-PAM acetates are rapidly hydrolyzed. Both are highly water soluble and give large changes in molar absorbance upon hydrolysis. Hence, they have potential ...

G. M. Steinberg J. P. Maddox L. J. Szafraniec L. M. Berkowitz N. C. Thomas

1971-01-01

299

Kallolide A acetate pyrazoline  

PubMed Central

In the crystal structure of kallolide A acetate pyrazoline [systematic name: 7-methyl-16-oxo-4,10-bis­(prop-1-en-2-yl)-17,18-dioxa-14,15-diaza­tetra­cyclo­[9.4.2.16,9.01,12]octa­deca-6,8,14-trien-5-yl acetate], C23H28N2O5, there is a 12-member­ed carbon macrocyclic structure. In addition, there is a tris­ubstituted furan ring, an approximately planar ?-lactone ring [maximum deviation of 0.057?(3)?Å] and a pyraz­oline ring, the latter in an envelope conformation. The pyrazoline and the ?-lactone rings are fused in a cis configuration. In the crystal, mol­ecules are linked by weak C—H?O inter­actions, forming a two-dimensional network parallel to (001). An intra­molecular C—H?O hydrogen bond is also present.

Rodriguez-Escudero, Idaliz; Marrero, Jeffrey; Rodriguez, Abimael D.

2012-01-01

300

Low Noise Buffer Amplifiers and Buffered Phase Comparators for Precise Time and Frequency Measurement and Distribution.  

National Technical Information Service (NTIS)

Extremely low noise, high performance, wideband buffer amplifiers and buffered phase comparators have been developed for the NASA Goddard Space Flight Center Atomic Hydrogen Standards Program. These buffer amplifiers are designed to distribute reference f...

J. S. Ingold P. Dachel R. A. Eichinger W. H. Miller

1981-01-01

301

Influence of glyphosate on the copper dissolution in phosphate buffer  

NASA Astrophysics Data System (ADS)

The electrochemical behavior of copper microelectrode in phosphate buffer in the presence of glyphosate was investigated by electrochemical techniques. It was observed that the additions of glyphosate in the phosphate buffer increased the anodic current of copper microelectrode and the electrochemical dissolution was observed. This phenomenon could be associated with the Cu(II) complexation by glyphosate forming a soluble complex. Physical characterization of the surface showed that, in absence of glyphosate, an insoluble layer covered the copper surface; on the other hand, in presence of glyphosate, it was observed a corroded copper surface with the formation of glyphosate complex in solution.

Coutinho, C. F. B.; Silva, M. O.; Machado, S. A. S.; Mazo, L. H.

2007-01-01

302

Effect of the Buffer Concentration on the Separation of Lactate Dehydrogenase Isoenzymes from Different Sources by Electrophoresis  

Microsoft Academic Search

The separation of lactate dehydrogenase isoenzymes by zone electrophoresis using cellulose acetate strips as support was dependent on the concentration of the buffer used (5 mM and 50 mM, pH 7.4) and on the source of the material (chicken liver or guinea-pig liver).In three different 5 mM buffer systems, pH 7.4 (phosphate, veronal and Tris-HC1) the four lactate dehydrogenase isoenzymes

S. Imperial; J. Li Gelpí; M. Busquets; A. Mazo; A. Cortés

1991-01-01

303

Effects of PH, CO2, and Buffering Systems on Lactic Acid Production in Rat Liver Slices.  

National Technical Information Service (NTIS)

In an effort to reveal the separate effects of pH, CO2, and the type of buffering agent on lactate production, rat liver slices were incubated in Krebs-Ringer solution using three different buffers equilibrated with either O2 or 5% CO2 in O2 and at three ...

W. G. Soucie

1969-01-01

304

Effect of Buffers on the Pectolytic Activity of Culture Filtrates of Fusarium oxysporum  

Microsoft Academic Search

PECTOLYTIC enzymes have been implicated in the disintegration of plant tissue by a number of phytopathogenic bacteria and fungi1. One procedure to assay culture filtrates for pectolytic activity requires a demonstration of a loss of viscosity for a solution of sodium polypectate or pectin in buffer, using a viscosimeter2. This communication presents results of the effect of 4 buffers at

J. A. Meyer; E. D. Garber; Susan G. Shaeffer

1964-01-01

305

Plasma acetate turnover and oxidation.  

PubMed Central

Plasma acetate turnover and oxidation were determined in 11 healthy subjects by the constant infusion of a trace amount of [1-14C]acetate for 6 h. The subjects ages ranged from 22 to 57 yr. There was a positive correlation (P less than 0.001) between plasma acetate concentration and turnover rate, and a negative correlation (P less than 0.001) between turnover and age. The plasma acetate concentration in the subjects 22--28 yr old was 0.17 vs. 0.13 mM (P less than 0.02) in subjects 40--57 yr old. The plasma acetate turnover rate was also greater in the younger age group (8.23 +/- 0.66 vs. 4.98 +/- 0.64 mumol/min . kg, P less than 0.01). Approximately 90% of the plasma acetate turnover was immediately oxidized to CO2 in both age groups, however, 13.2 +/- 0.89% of the CO2 output in the younger group was derived from plasma acetate oxidation compared to 7.9 +/- 0.94% in the older group (P less than 0.01). The mean plasma acetate concentration, turnover, and oxidation in six cancer patients 47--63 yr old were similar to the values observed in the age-matched healthy subjects. Uptake or output of acetate by various tissues was measured by arterial-venous plasma acetate concentration differences. In seven of eight subjects undergoing elective surgery, the arterial-portal venous concentration difference was negative, which indicated that the gastrointestinal tract can contribute to plasma acetate production. Uptake of plasma acetate by both the leg and liver appeared to be dictated by the arterial acetate concentration. Net production of acetate by both the leg and liver was most often observed at arterial plasma acetate concentrations less than 0.08 mM.

Skutches, C L; Holroyde, C P; Myers, R N; Paul, P; Reichard, G A

1979-01-01

306

The effect of electric field strength, buffer type and concentration on separation parameters in capillary zone electrophoresis  

Microsoft Academic Search

Summary  Probe solutes were used to investigate the effect of buffer type, concentration and applied voltage on solute mobility, column\\u000a efficiency and resolution in capillary zone electrophoresis. With low conductivity buffers higher concentrations and\\/or higher\\u000a voltages could be used to improve column efficiency and resolution. Doubling the concentration of the buffer doubles the amount\\u000a of heat generated inside the column while

H. J. Issaq; I. Z. Atamna; G. M. Muschik; G. M. Janini

1991-01-01

307

46 CFR 58.25-45 - Buffers.  

Code of Federal Regulations, 2012 CFR

...25-45 Buffers. For each vessel on an ocean, coastwise, or Great Lakes voyage, steering gear other than hydraulic must be designed with suitable buffering arrangements to relieve the gear from shocks to the...

2012-10-01

308

46 CFR 58.25-45 - Buffers.  

Code of Federal Regulations, 2011 CFR

...25-45 Buffers. For each vessel on an ocean, coastwise, or Great Lakes voyage, steering gear other than hydraulic must be designed with suitable buffering arrangements to relieve the gear from shocks to the...

2011-10-01

309

Examining the Distribution of Buffer Protection  

Microsoft Academic Search

This paper examines the stochastic behavior of buffer protection (in-process inventory storage) in an 2V-machine single-buffer series system. The approach is specifically developed for unbalanced production lines (i.e., the minimum production rate of those machines preceding the buffer is different than the minimum production rate of those machines following the buffer). For the case of exponential uptimes and general downtimes,

Richard A. Murphy

1979-01-01

310

Legitimate Skew Clock Routing with Buffer Insertion  

Microsoft Academic Search

In this paper, we propose a new quick and effective legitimate skew clock routing with buffer insertion algorithm. We analyze\\u000a the optimal buffer position in the clock path, and conclude the sufficient condition and heuristic condition for buffer insertion\\u000a in clock net. During the routing process, this algorithm integrates buffer insertion and node merging together, and performs\\u000a them in parallel.

Xinjie Wei; Yici Cai; Meng Zhao; Xianlong Hong

2006-01-01

311

Buffer Layer R and D for YBCO Coated Conductor Composite Wires  

SciTech Connect

Buffer layers play a key role in the YBa2Cu3O7-{delta} (YBCO) coated conductor composite wire technology. The important buffer layer characteristics are: these buffers should prevent metal diffusion into the superconductor from the substrate; possibly act as oxygen diffusion barriers; should be smooth, continuous, crack-free, highly aligned and dense. In order to develop low-cost alternative buffer layer architectures to the standard architecture of YBCO/CeO2/YSZ/Y2O3/Ni/Ni-W, LaMnO3 (LMO) and La2Zr2O7 (LZO) buffers were chosen for this study. These buffers were grown epitaxially on biaxially textured and strengthened Ni-W3% metal tapes by scalable vapor and/or solution techniques. LaMnO3 buffers were grown epitaxially on Ni-W substrates by rf sputtering, and La2Zr2O7 buffers were grown by a Metal-Organic Deposition (MOD). Detailed microstructural characterizations indicate that both of these buffers were excellent Ni diffusion barrier layers and high current YBCO films were grown on both LMO and LZO buffer templates.

Paranthaman, M. Parans; Sathyamurthy, S.; Aytug, T.; Leonard, K.J.; Goyal, A.; Zhai, H.Y.; Kroeger, D.M.; Christen, D.K. [Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States); Li, X.; Verebelyi, D.T.; Schoop, U.; Thieme, C.; Kodenkandath, T.; Zhang, W.; Rupich, M.W. [American Superconductor Corporation, Westborough, MA 01581 (United States); Ericson, R.E. [3M Company, St. Paul, MN 55144 (United States)

2004-06-28

312

Effects of buffer concentration on voltage-gated H+ currents: does diffusion limit the conductance?  

PubMed Central

The single-channel proton conductance of the voltage-gated H(+)-selective channel, like that of the F0 component of the H(+)-ATPase, is nearly constant over a wide range of pH encompassing the physiological range. To examine the possible contributions of buffer diffusion and buffer-channel proton transfer reactions to this phenomenon, the effects of buffer concentration on voltage-activated H+ currents were explored in voltage-clamped rat alveolar epithelial cells. Changes in the external buffer concentration ([B]o), evaluated using the whole-cell configuration, had only small effects on H+ currents (IH). Lowering [B]o from 100 to 1 mM did not alter the voltage-activation curve or reversal potential (Vrev) but reduced IH, typically by 10-30%. Changes in internal buffer concentration ([B]i), examined in inside-out patches, usually altered IH more distinctly and subtly changed the kinetics. Overall, the effects of changing buffer concentration were small and subtle. The maximum attenuation of the single-channel H+ current at 1 mM buffer was estimated to be approximately 20% at either mouth of the H+ channel. Therefore, the rate-determining step in H+ permeation is neither deprotonation of buffer at the inner mouth of the channel nor protonation of buffer at the external surface. Evidently the rate of H+ permeation through the channel is itself small enough that diffusion of buffer in bulk solution does not directly limit the conductance significantly.

DeCoursey, T E; Cherny, V V

1996-01-01

313

Buffer Layer R&D for YBCO Coated Conductor Composite Wires  

NASA Astrophysics Data System (ADS)

Buffer layers play a key role in the YBa2Cu3O7-? (YBCO) coated conductor composite wire technology. The important buffer layer characteristics are: these buffers should prevent metal diffusion into the superconductor from the substrate; possibly act as oxygen diffusion barriers; should be smooth, continuous, crack-free, highly aligned and dense. In order to develop low-cost alternative buffer layer architectures to the standard architecture of YBCO/CeO2/YSZ/Y2O3/Ni/Ni-W, LaMnO3 (LMO) and La2Zr2O7 (LZO) buffers were chosen for this study. These buffers were grown epitaxially on biaxially textured and strengthened Ni-W3% metal tapes by scalable vapor and/or solution techniques. LaMnO3 buffers were grown epitaxially on Ni-W substrates by rf sputtering, and La2Zr2O7 buffers were grown by a Metal-Organic Deposition (MOD). Detailed microstructural characterizations indicate that both of these buffers were excellent Ni diffusion barrier layers and high current YBCO films were grown on both LMO and LZO buffer templates.

Paranthaman, M. Parans; Sathyamurthy, S.; Aytug, T.; Leonard, K. J.; Goyal, A.; Zhai, H. Y.; Kroeger, D. M.; Christen, D. K.; Li, X.; Verebelyi, D. T.; Schoop, U.; Thieme, C.; Kodenkandath, T.; Zhang, W.; Rupich, M. W.; Ericson, R. E.

2004-06-01

314

Spectrophotometric flow-injection analysis of the total base number in lubricants by using acid–base buffers  

Microsoft Academic Search

A spectrophotometric FIA method for the determination of the total base number (TBN) in a lubricant was proposed, which involved using an acid–base buffer solution prepared with a nonaqueous solvent. This method is based on measurements of the absorbance change of an indicator contained in the acid–base buffer solution, which is generated due to a neutralization reaction of base in

Keiko Jyonosono; Toshihiko Imato; Noriyuki Imazumi; Masayuki Nakanishi; Jun-ichi Yagi

2001-01-01

315

RESEARCH NEEDS IN RIPARIAN BUFFER RESTORATION  

EPA Science Inventory

Riparian buffer restorations are used as management tools to produce favorable water quality impacts; moreover, the basis for riparian buffers as an instrument of water quality restoration rests on a relatively firm foundation. However, the extent to which buffers can restore rip...

316

Baroresistant buffer mixtures for biochemical analyses  

Microsoft Academic Search

Hydrostatic pressure is a useful tool in the study of varied fields such as protein aggregation, association, folding, ligand binding, and allostery. Application of pressure can have a significant effect on the pKa values of buffers commonly used for biochemical analysis. Consequently, cationic buffers, rather than neutral ones, are generally used to minimize pH effects; however, even with these buffers,

R. Jason Quinlan; Gregory D. Reinhart

2005-01-01

317

Buffer management in relational database systems  

Microsoft Academic Search

The hot-set model, characterizing the buffer requirements of relational queries, is presented. This model allows the system to determine the optimal buffer space to be allocated to a query; it can also be used by the query optimizer to derive efficient execution plans accounting for the available buffer space, and by a query scheduler to prevent thrashing. The hot-set model

Giovanni Maria Sacco; Mario Schkolnick

1986-01-01

318

Buffer sizing for congested Internet links  

Microsoft Academic Search

Packet buffers in router\\/switch interfaces constitute a central element of packet networks. The appropriate sizing of these buffers is an important and open research problem. Much of the previous work on buffer sizing modeled the traffic as an exogenous process, i.e., independent of the network state, ignoring the fact that the offered load from TCP flows depends on delays and

Amogh Dhamdhere; Hao Jiang; Constantinos Dovrolis

2005-01-01

319

Doped LZO buffer layers for laminated conductors  

SciTech Connect

A laminated conductor includes a metallic substrate having a surface, a biaxially textured buffer layer supported by the surface of the substrate, the biaxially textured buffer layer comprising LZO and a dopant for mitigating metal diffusion through the LZO, and a biaxially textured conductor layer supported by the biaxially textured buffer layer.

Paranthaman, Mariappan Parans (Knoxville, TN); Schoop, Urs (Westborough, MA); Goyal, Amit (Knoxville, TN); Thieme, Cornelis Leo Hans (Westborough, MA); Verebelyi, Darren T. (Oxford, MA); Rupich, Martin W. (Framingham, MA)

2010-03-23

320

Improving Water Quality With Conservation Buffers  

NASA Astrophysics Data System (ADS)

Conservation buffer technologies are new approaches that need wider application. In-field buffer practices work best when used in combination with other buffer types and other conservation practices. Vegetative barriers may be used in combination with edge-of-field buffers to protect and improve their function and longevity by dispersing runoff and encouraging sediment deposition upslope of the buffer. It's important to understand how buffers can be managed to help reduce nutrient transport potential for high loading of nutrients from manure land application sites, A restored riparian wetland buffer retained or removed at least 59 percent of the nitrogen and 66 percent of the phosphorus that entered from an adjacent manure land application site. The Bear Creek National Restoration Demonstration Watershed project in Iowa has been the site of riparian forest buffers and filter strips creation; constructed wetlands to capture tile flow; stream-bank bioengineering; in-stream structures; and controlling livestock grazing. We need field studies that test various widths of buffers of different plant community compositions for their efficacy in trapping surface runoff, reducing nonpoint source pollutants in subsurface waters, and enhancing the aquatic ecosystem. Research is needed to evaluate the impact of different riparian grazing strategies on channel morphology, water quality, and the fate of livestock-associated pathogens and antibiotics. Integrating riparian buffers and other conservation buffers into these models is a key objective in future model development.

Lowrance, R.; Dabney, S.; Schultz, R.

2003-12-01

321

Food waste decomposition in leachbed reactor: Role of neutralizing solutions on the leachate quality  

Microsoft Academic Search

The neutralization effects of 0.1M NaHCO3, KPO4-buffer (pH 7.0) and sodium acetate (NaOAc) solutions (500ml\\/kg food waste\\/day) on controlling the pH and leachate quality in an acidogenic reactor of food waste anaerobic digestion was investigated. pH of leachate from the reactor was low and ranged from 3.24 to 4.15. Although differences in chemical oxygen demand (COD) were observed, the cumulative

Ammaiyappan Selvam; Su Yun Xu; Xiang Yang Gu; Jonathan W. C. Wong

2010-01-01

322

Acetate metabolism in Methanosarcina barkeri  

Microsoft Academic Search

Methanosarcina barkeri was grown by acetate fermentation in complex medium (N2 gas phase). The molar growth yield was 1.6–1.9 g cells\\/mol methane formed. Under these conditions 63–82% of the methane produced byMethanosarcina strains was derived from the methyl carbon of acetate, indicating that some methane was derived from other media components. Growth was not demonstrated in complex media lacking acetate

P. J. Weimer; J. G. Zeikus

1978-01-01

323

Buffered Electrochemical Polishing of Niobium  

SciTech Connect

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

Gianluigi Ciovati, Hui Tian, Sean Corcoran

2011-03-01

324

Factors That Influence Mobility, Resolution, and Selectivity in Capillary Zone Electrophoresis. III. The Role of the Buffers' Anion  

Microsoft Academic Search

A study of the anion of the buffer and its effect on electroosmotic flow, mobility times, resolution and selectivity was undertaken. The anions selected acetate, borate, phosphate, citrate, carbonate, nitrate and nitrite, gave widely different currents at the same applied voltage (20 kV). Carbonate produced the lowest current, while citrate produced the highest current. Also, it was found that the

Ibrahim Z. Atamna; Climaco J. Metral; Gary M. Muschik; Haleem J. Issaq

1990-01-01

325

Kinetics of Imidazole Catalyzed Ester Hydrolysis: Use of Buffer Dilutions to Determine Spontaneous Rate, Catalyzed Rate, and Reaction Order.  

ERIC Educational Resources Information Center

|Described is an advanced undergraduate kinetics experiment using buffer dilutions to determine spontaneous rate, catalyzed rate, and reaction order. The reaction utilized is hydrolysis of p-nitro-phenyl acetate in presence of imidazole, which has been shown to enhance rate of the reaction. (Author/JN)|

Lombardo, Anthony

1982-01-01

326

[Nomegestrol acetate: clinical pharmacology].  

PubMed

Progestogens are used in clinical practice in some conditions. Their effects depend on their chemical structure, pharmacokinetics, pharmacodynamics, with important differences among various progestogens. Generally, progestins are classified according to their parent molecule, of which often they keep some features. Derivatives of 19-nor-progesterone are characterized by high selectivity of action on progestin receptor. In particular, nomegestrol acetate (NomAc) shows an important progestational potency, neutral gluco-lipid profile, and antigonadotropic activity. It is used for treating menstrual cycle disorders and for hormone replacement therapy in menopause in association with an estrogen. In future, thanks to its antigonadotropic activity, NomAc will be used in estroprogestin combinations in fertile women, thus taking advantage of its tolerability profile and obtaining numerous non-contraceptive benefits as well. PMID:19749678

Lello, S

2009-10-01

327

Optimization of resolution in capillary zone electrophoresis: combined effect of applied voltage and buffer concentration.  

PubMed

Expressions are formulated for the prediction of solute migration time and resolution as a function applied voltage and buffer concentration in capillary zone electrophoresis. The resolution equation assumes that solute diffusion is the only operative zone-broadening mechanism. A resolution surface in applied voltage and buffer concentration space is presented featuring isochrones that are used to predict the behavior of resolution under constant analysis time. In the resolution-voltage planes the resolution increases continuously with increasing voltage. At the high-voltage border, the resolution decreases continuously with increasing concentration, however, at the low-voltage border the resolution passes through a shallow maximum as the buffer concentration is increased. At constant analysis time, resolution is optimized by simultaneously increasing the voltage and the buffer concentration. In comparison, this theoretical approach, which predicts resolution from solute migration times only, gives values that are consistently about 40-50% higher than experimentally determined resolution. PMID:1818085

Atamna, I Z; Issaq, H J; Muschik, G M; Janini, G M

1991-12-27

328

Interactive Video Service By Means of Multicasting and Client Buffering  

Microsoft Academic Search

True-VOD provides interactive on-demand (i.e., virtually zero start-up delay) video service by allocating each user a dedicated stream. Such streaming tech- nique, however, cannot scale up to accommodate a large number of users. A more scalable solution is to use multicasting and client buffering. In this paper, we propose a client-initiated (client-pull) on-demand scheme in which short unicast streams are

S.-H. Gary; Edward Chang

329

Thermogravimetric analysis of the relationship among calcium magnesium acetate, calcium acetate and magnesium acetate  

Microsoft Academic Search

Thermal decomposition characteristic of calcium magnesium acetate (CMA), calcium acetate (CA) and magnesium acetate (MA) are investigated through thermogravimetric (TG) analysis at the heating rates of 5Kmin?1, 7.5Kmin?1, 10Kmin?1 and 15Kmin?1. After dehydration, the evaporation of carboxylic radical and carbon dioxide of CMA and CA exist in two separate segments, but for MA, this occurs together in just one segment

Shengli Niu; Kuihua Han; Chunmei Lu; Rongyue Sun

2010-01-01

330

Buffer requirements for enhanced hydrogen production in acidogenic digestion of food wastes.  

PubMed

The requirements for pH buffer addition for hydrogen production and acidogenesis in batch acidogenic digestion of a food waste (FW) feedstock with limited alkalinity was studied at various initial pH conditions (6.0-8.0). The results showed that, without buffer addition, hydrogen production from this feedstock was insignificant regardless of the initial pH. With buffer addition, hydrogen production improved significantly if the initial pH was greater than 6.0. Substantial hydrogen production occurred when the pH at the end of the batch digestion was higher than 5.5. The maximum hydrogen production was found to be 120 mL/g VS added when the initial pH was 6.5 and buffer addition was in the range of 15-20 mmol/g VS. The effect of pH buffering on the formation of volatile fatty acids (acetic acid, propionic acid and butyric acid) was similar to its effect on hydrogen production. The results of this study clearly indicated shifts in the metabolic pathways with the pH of fermentation. The changes in metabolic pathways impacted upon the dosage of buffer that was required to achieve maximum hydrogen generation. PMID:19576761

Zhu, Heguang; Parker, Wayne; Basnar, Robert; Proracki, Alex; Falletta, Pat; Béland, Michel; Seto, Peter

2009-07-02

331

Stabilized Calcium Acetate Oil Dispersions.  

National Technical Information Service (NTIS)

A lubricating composition is imparted with improved load-carrying ability and anti-wear properties by incorporation of calcium acetate. The composition consists of a base lubricant, 0.1 to 50 percent by weight calcium acetate and 0.01 to 20 percent by wei...

R. H. Davis

1965-01-01

332

Lead Acetate, Radiotracer Metabolism Study.  

National Technical Information Service (NTIS)

Metabolic studies utilizing radiotracer techniques were applied to tissues from rats which had received 0 and 1000 ppm lead acetate (calculated as lead) for one month prior to the oral administration of 210 lead acetate. Seventy-two hours after administra...

D. C. Jessup

1967-01-01

333

Potassium buffering in the central nervous system  

Microsoft Academic Search

Rapid changes in extracellular K+ concentration ([K+]o) in the mammalian CNS are counteracted by simple passive diffusion as well as by cellular mechanisms of K+ clearance. Buffering of [K+]o can occur via glial or neuronal uptake of K+ ions through transporters or K+-selective channels. The best studied mechanism for [K+]o buffering in the brain is called K+ spatial buffering, wherein

P. Kofuji; E. A. Newman

2004-01-01

334

Unit 8: Buffers for Biochemical Reactions  

NSDL National Science Digital Library

The last of an eight-unit teaching and training module from Promega, this "introductory buffers laboratory is for use in undergraduate or highschool courses that cover basic topics in molecular biology or biochemistry" and includes "laboratories to illustrate basic chemistry concepts related to buffers and their functions." This unit is math-intensive, aimed at helping students feel comfortable performing laboratory calculations. It includes a lecture presentation ("Buffers for Biological Systems") and a students' and instructors' laboratory protocol.

2013-07-05

335

Buffers Strips, Common-Sense Conservation  

NSDL National Science Digital Library

This recent publication from the Natural Resources Conservation Service (NRCS) and the National Conservation Buffer Team focuses on the practices, agricultural programs, and national programs that promote conservation buffers -- "strips or small areas of land in permanent vegetation" to help control potential pollutants and other environmental concerns. NRCS outlines specific programs and educational initiatives for many different types of "filter strips, field borders, grassed waterways, field windbreaks, shelterbelts, contour grass strips, and riparian (streamside) buffers."

336

Self-assembly of diorganotin(IV) 2-{[( E)-1-(2-oxyaryl)alkylidene]amino}acetates: An investigation of structures by X-ray diffraction, solution and solid-state tin NMR, and electrospray ionization MS  

Microsoft Academic Search

The diorganotin(IV) compounds, [Me2SnL2(OH2)]2 (1), [nBu2SnL2(OH2)]2 (2), [nBu2SnL1]3·0.5C3H6O (3), [nBu2SnL3]3·0.5C6H6 (4) and [Ph2SnL3]n·0.5C6H6 (5) (L=carboxylic acid residue, i.e., 2-{[(E)-1-(2-oxyaryl)alkylidene]amino}acetate), were synthesized by treating the appropriate diorganotin(IV) dichloride with the potassium salt of the ligand in anhydrous methanol.The reaction of Ph2SnL2 (L=2-{[(E)-1-(2-oxyphenyl)ethylidene]amino}acetate) with 1,10-phenanthroline (Phen) yielded a 1:1 adduct of composition, [Ph2SnL2(Phen)] (6).The crystal structures of 1–6 were determined.The crystal of

Tushar S. Basu Baul; Cheerfulman Masharing; Rudolph Willem; Monique Biesemans; Michal Hol?apek; Robert Jirásko; Anthony Linden

2005-01-01

337

Thin La2Zr2O7 films made from a water-based solution  

NASA Astrophysics Data System (ADS)

Thin films of La2Zr2O7 (LZO) are highly regarded as possible buffer layers in the coated conductor configuration. This report describes a new synthesis for thin crystalline LZO films, based on a largely water-based solution, mainly containing metal acetates, acetic acid and an organic amine-base: triethanolamine. Initially, a thin layer of amorphous material is deposited on the textured Ni-5 at%W substrate by means of dip-coating. Only by careful control of the thermal treatment can the layer be transformed into a crystalline layer. Important parameters in this respect are the heating rate and the dwell time. The amorphous gel is analysed by HR-TGA/DTA and HR-TEM. The textured layers are analysed by XRD, pole figures, RHEED, AFM and SEM.

Cloet, V.; Feys, J.; Hühne, R.; Hoste, S.; van Driessche, I.

2009-01-01

338

Extraction of 3D Transition Metals from Molten Cesium-Sodium-Potassium/Acetate Eutectic into Dodecane Using Organophosphorous Ligands.  

National Technical Information Service (NTIS)

Measurements have been made of the transfer of the transition metal cations Cr exp 3+ , Fe exp 2+ , Co exp 2+ , Ni exp 2+ from molten cesium acetate-sodium acetate-potassium acetate eutectic (50-25-25 mol%, mp approx. 90 exp 0 C) into dodecane solutions c...

V. A. Maroni C. E. Philbin R. M. Yonco

1983-01-01

339

Synthesis of vinyl acetate\\/Pd nanocomposites as activator ink for ink-jet printing technology and electroless copper plating  

Microsoft Academic Search

A novel method for the preparation of palladium (Pd) nanoparticles reduced by vinyl acetate (VAc) oligomers is presented in this study. VAc was synthesized by free radical polymerization method which was based on vinyl acetate\\/potassium persulfate (KPS)\\/water system. The noble metal nanoparticles reduced and stabilized by vinyl acetate oligomer showed their well dispersion in the aqueous solution without surfactant and

Chun-Chieh Tseng; Yeuh-Hui Lin; Youn-Yuen Shu; Chun-Jen Chen; Ming-Der Ger

2011-01-01

340

New approach for the production of cellulose acetate: acetylation of mechanical pulp with subsequent isolation of cellulose acetate by differential solubility  

Microsoft Academic Search

A heretofore uninvestigated approach to the production of cellulose acetate is the acetylation of mechanical pulp with subsequent isolation of the cellulose derivative by differential solubility. The mechanical pulp is produced by refining aspen wood chips in a disc-refiner. Two conventional acetylation techniques, the fibrous and solution process, are employed to acetylate all components of the pulp. The cellulose acetate

Barkalow

1987-01-01

341

Simultaneous determination of 2-naphthoxyacetic acid and indole-3-acetic acid by first derivation synchronous fluorescence spectroscopy  

NASA Astrophysics Data System (ADS)

A simple, rapid, sensitive and selective method for simultaneously determining 2-naphthoxyacetic acid (BNOA) and Indole-3-Acetic Acid (IAA) in mixtures has been developed using derivation synchronous fluorescence spectroscopy based on their synchronous fluorescence. The synchronous fluorescence spectra were obtained with ?? = 100 nm in a pH 8.5 NaH2PO4-NaOH buffer solution, and the detected wavelengths of quantitative analysis were set at 239 nm for BNOA and 293 nm for IAA respectively. The over lapped fluorescence spectra were well separated by the synchronous derivative method. Under optimized conditions, the limits of detection (LOD) were 0.003 ?g/mL for BNOA and 0.012 ?g/mL for IAA. This method is simple and expeditious, and it has been successfully applied to the determination of 2-naphthoxyacetic acid and indole-3-acetic acid in fruit juice samples with satisfactory results. The samples were only filtrated through a 0.45 ?m membrane filter, which was free from the tedious separation procedures. The obtaining recoveries were in the range of 83.88-87.43% for BNOA and 80.76-86.68% for IAA, and the relative standard deviations were all less than 5.0%. Statistical comparison of the results with high performance liquid chromatography Mass Spectrometry (HPLC-MS) method revealed good agreement and proved that there were no significant difference in the accuracy and precision between these two methods.

Liu, Xiangxiang; Wan, Yiqun

2013-07-01

342

Experimental acidification of two biogeochemically-distinct neotropical streams: buffering mechanisms and macroinvertebrate drift.  

PubMed

Research into the buffering mechanisms and ecological consequences of acidification in tropical streams is lacking. We have documented seasonal and episodic acidification events in streams draining La Selva Biological Station, Costa Rica. Across this forested landscape, the severity in seasonal and episodic acidification events varies due to interbasin groundwater flow (IGF). Streams that receive IGF have higher concentrations of solutes and more stable pH (~6) than streams that do not receive IGF (pH ~5). To examine the buffering capacity and vulnerability of macroinvertebrates to short-term acidification events, we added hydrochloric acid to acidify a low-solute, poorly buffered (without IGF) and a high-solute, well buffered stream (with IGF). We hypothesized that: 1) protonation of bicarbonate (HCO(3)(-)) would neutralize most of the acid added in the high-solute stream, while base cation release from the sediments would be the most important buffering mechanism in the low-solute stream; 2) pH declines would mobilize inorganic aluminum (Ali) from sediments in both streams; and 3) pH declines would increase macroinvertebrate drift in both streams. We found that the high-solute stream neutralized 745 ?eq/L (96% of the acid added), while the solute poor stream only neutralized 27.4 ?eq/L (40%). Protonation of HCO(3)(-) was an important buffering mechanism in both streams. Base cation, Fe(2+), and Ali release from sediments and protonation of organic acids also provided buffering in the low-solute stream. We measured low concentrations of Ali release in both streams (2-9 ?eq/L) in response to acidification, but the low-solute stream released double the amount Ali per 100 ?eq of acid added than the high solute stream. Macroinvertebrate drift increased in both streams in response to acidification and was dominated by Ephemeroptera and Chironomidae. Our results elucidate the different buffering mechanisms in tropical streams and suggest that low-solute poorly buffered streams might be particularly vulnerable to episodic acidification. PMID:23201647

Ardón, Marcelo; Duff, John H; Ramírez, Alonso; Small, Gaston E; Jackman, Alan P; Triska, Frank J; Pringle, Catherine M

2012-11-28

343

Pb(II) and Zn(II) adsorption onto Na and Ca-montmorillonites in acetic acid\\/acetate medium: Experimental approach and geochemical modeling  

Microsoft Academic Search

Smectites are usually used as a clay barrier at the bottom of subsurface waste landfills due to their low permeability and their capacity to retain pollutants. The Na- and Ca-saturated SWy2 montmorillonites were interacted with initial Zn(NO3)2 or Pb(NO3)2 concentrations ranging from 10?6 to 10?2M with a solid\\/liquid ratio of 10gL?1 and using acetic acid\\/acetate as buffer at pH 5

Mariem Ghayaza; Lydie Le Forestier; Fabrice Muller; Christophe Tournassat; Jean-Michel Beny

2011-01-01

344

21 CFR 178.1010 - Sanitizing solutions.  

Code of Federal Regulations, 2013 CFR

...aqueous solution containing hydrogen peroxide (CAS Reg. No. 7722-84-1...aqueous solution containing hydrogen peroxide (CAS Reg. No. 7722-84-1...45) An aqueous solution of hydrogen peroxide, acetic acid,...

2013-04-01

345

21 CFR 184.1185 - Calcium acetate.  

Code of Federal Regulations, 2013 CFR

...also known as acetate of lime or vinegar salts, is the calcium salt of acetic acid. It may be produced by the calcium hydroxide neutralization of acetic acid. (b) The ingredient meets the specifications of the Food Chemicals...

2013-04-01

346

Buffer Asymptotics for Coding Over Networks  

Microsoft Academic Search

Traditionally, network buffer resources have been used at routers to queue transient packets to prevent packet drops. In contrast, we propose a scheme for large multihop networks where intermediate routers have no buffers for queueing transient packets. In the proposed scheme, network storage resources (memory) are used only at source and destination nodes to encode\\/decode packets using random linear coding

Sandeep Bhadra; Sanjay Shakkottai

2010-01-01

347

Box Calculus with High-Level Buffers  

Microsoft Academic Search

In this paper, we propose a high-level process algebra al- lowing to express the exchange of data values using both handshake and buffered communication. This allows a sim- ple and compositional expression of interprocess communi- cation; in particular the buffered one makes easy the repre- sentation of program variables, allowing a compact repre- sentation of large systems. The process terms

Cécile Bui Thanh; Hanna Klaudel; Franck Pommereau

348

Scheduling in switches with small internal buffers  

Microsoft Academic Search

Unbuffered crossbars or switching fabrics contain no internal buffers, and function using only input (VOQ) and possibly output queues. Schedulers for such switches are complex, and introduce increased delay at medium loads, because they have to admit at most one cell per input and per output, during each time slot. Buffered crossbars, on the other hand, contain Q sufficient internal

Nikos Chrysos; Manolis Katevenis

2005-01-01

349

Reducing State Changes with a Pipeline Buffer  

Microsoft Academic Search

A limiting factor in the performance of a render- ing system is the number of state changes, i.e., changes of the attributes material, texture, shader program, etc., in the stream of rendered primitives. We propose to include a small buffer between appli- cation and graphics hardware in the rendering sys- tem. This pipeline buffer is used to rearrange the incoming

Jens Krokowski; Harald Räcke; Christian Sohler; Matthias Westermann

2004-01-01

350

African American College Women's Suicide Buffers.  

ERIC Educational Resources Information Center

|To examine the relationships buffers may have with suicide ideation, 300 African American female college students completed measures of suicide ideation and buffers. Three variables accounted for a significant and unique portion of the variance in suicide ideation: family support, a view that suicide is unacceptable, and a collaborative religious…

Marion, Michelle S.; Range, Lillian M.

2003-01-01

351

African American College Women's Suicide Buffers.  

ERIC Educational Resources Information Center

To examine the relationships buffers may have with suicide ideation, 300 African American female college students completed measures of suicide ideation and buffers. Three variables accounted for a significant and unique portion of the variance in suicide ideation: family support, a view that suicide is unacceptable, and a collaborative religious…

Marion, Michelle S.; Range, Lillian M.

2003-01-01

352

Modeling buffer layer IGBTs for circuit simulation  

Microsoft Academic Search

The dynamic behavior of commercially available buffer layer IGBTs is described. It is shown that buffer layer IGBTs become much faster at high voltages than nonbuffer layer IGBTs with similar low voltage characteristics. Because the fall times specified in manufacturers' data sheets do not reflect the voltage dependence of switching speed, a new method of selecting devices for different circuit

1995-01-01

353

Buffer insertion for noise and delay optimization  

Microsoft Academic Search

Buffer insertion has successfully been applied to reduce delay in global interconnect paths; however, existing techniques only optimize delay and timing slack. With the increasing ratio of coupling to total capacitance and the use of aggressive dynamic logic circuit families, noise is becoming a major design bottleneck. We present comprehensive buffer insertion techniques for noise and delay optimization. Our experiments

Charles J. Alpert; Anirudh Devgan; Stephen T. Quay

1998-01-01

354

46 CFR 58.25-45 - Buffers.  

Code of Federal Regulations, 2010 CFR

... Shipping 2 2009-10-01 2009-10-01 false Buffers. 58.25-45 Section 58.25-45 Shipping COAST...MACHINERY AND RELATED SYSTEMS Steering Gear § 58.25-45 Buffers. For each vessel on an ocean, coastwise, or Great...

2009-10-01

355

46 CFR 58.25-45 - Buffers.  

Code of Federal Regulations, 2010 CFR

... Shipping 2 2010-10-01 2010-10-01 false Buffers. 58.25-45 Section 58.25-45 Shipping COAST...MACHINERY AND RELATED SYSTEMS Steering Gear § 58.25-45 Buffers. For each vessel on an ocean, coastwise, or Great...

2010-10-01

356

Color image quantization for frame buffer display  

Microsoft Academic Search

Algorithms for adaptive, tapered quantization of color images are described. The research is motivated by the desire to display high-quality reproductions of color images with small frame buffers. It is demonstrated that many color images which would normally require a frame buffer having 15 bits per pixel can be quantized to 8 or fewer bits per pixel with little subjective

Paul Heckbert

1982-01-01

357

Buffer Management in a Packet Switch  

Microsoft Academic Search

Consider a single packet switch with a finite number of packet buffers shared between several output queues. An arriving packet is lost if no free buffer is available, as in the CIGALE network. It has been observed by simulation that if load increases too much, congestion may occur, i.e., throughput declines; it appears that the busiest link's queue tends to

MAREK I. IRLAND

1978-01-01

358

AUTOMATIC TRANSFER LINES WITH BUFFER STOCKS  

Microsoft Academic Search

The efficiency of an automatic transfer line can be increased by dividing the line into a number of stages and providing buffer stores between the stages.The results of a theoretical study of the effect of buffer stocks on automatic fixed cycle in line transfer machines are reported. It is shown how the improvement in efficiency depends on the number of

J. A. BUZACOTT

1967-01-01

359

Statically Detecting Likely Buffer Overflow Vulnerabilities  

Microsoft Academic Search

Buffer overflow attacks may be today's single most important security threat. This paper presents a new approach to mitigating buffer overflow vulnerabilities by detecting likely vulnerabilities through an analysis of the program source code. Our approach exploits information provided in semantic comments and uses lightweight and efficient static analyses. This paper describes an implementation of our approach that extends the

David Larochelle; David Evans

2001-01-01

360

Water Resource Protection by Riparian Buffer Zones  

Microsoft Academic Search

Growing switch-grass in a riparian buffer zone can be one of future best management practices in water resource protection. Switch-grass requires no fertilizers and less land and water. It was recently found to be a good source of biomass. In this study, Soil and Water Assessment Tool (SWAT) model was applied to a watershed to examine the effectiveness of buffer

Roy R. Gu; Mahesh K. Sahu

2010-01-01

361

Metal buffer layer inserted switchable mirrors  

Microsoft Academic Search

Thin buffer layers of hydrogen diffusive metals such as Ti, Nb, and V were inserted between a Mg4Ni thin film and a Pd top layer, which were prepared by DC magnetron sputtering. Their optical, electrochemical properties, and switching durability were investigated using both gasochromic and electrochromic switching methods. It has been proved that Ti, Nb, and V buffer layers can

S. Bao; K. Tajima; Y. Yamada; M. Okada; K. Yoshimura

2008-01-01

362

Draft Guidance on Norethindrone Acetate Active ingredient ...  

Center for Drug Evaluation (CDER)

Text VersionPage 1. Contains Nonbinding Recommendations Draft Guidance on Norethindrone Acetate ... Active ingredient: Norethindrone Acetate ... More results from www.fda.gov/downloads/drugs/guidancecomplianceregulatoryinformation

363

Inhibition of shoot geotropism by neutral buffers.  

PubMed

Submerged hypocotyl sections from Helianthus have been used to test the effect of neutral buffers on shoot geotropism. When hypocotyls have been abraded, it is found that increasing the molarity (0.25 to 20 mm) of pH 6.8 K-phosphate buffer, as well as other buffering systems, results in a strong inhibition of geotropic curvature. Buffer strength has no such effect on the curvature of nonabraded segments. One possible explanation for these data is that asymmetric shoot growth following geostimulation may require the establishment of a proton gradient across the cell walls of the shoot. When neutral buffers have access to the wall space (i.e. in abraded segments), they may prevent the establishment of such a gradient. PMID:16662175

Wright, L Z; Rayle, D L

1982-01-01

364

Optimization of protein buffer cocktails using Thermofluor.  

PubMed

The stability and homogeneity of a protein sample is strongly influenced by the composition of the buffer that the protein is in. A quick and easy approach to identify a buffer composition which increases the stability and possibly the conformational homogeneity of a protein sample is the fluorescence-based thermal-shift assay (Thermofluor). Here, a novel 96-condition screen for Thermofluor experiments is presented which consists of buffer and additive parts. The buffer screen comprises 23 different buffers and the additive screen includes small-molecule additives such as salts and nucleotide analogues. The utilization of small-molecule components which increase the thermal stability of a protein sample frequently results in a protein preparation of higher quality and quantity and ultimately also increases the chances of the protein crystallizing. PMID:23385769

Reinhard, Linda; Mayerhofer, Hubert; Geerlof, Arie; Mueller-Dieckmann, Jochen; Weiss, Manfred S

2013-01-31

365

Effects of Acetic Acid Pretreatment and Hot Air Drying on Resistance of Salmonella on Cabbage Slices  

Microsoft Academic Search

The heat resistance of Salmonella anatum inoculated onto the surface of cabbage slices as affected by acetic acid pretreatment (0.5–1.5% v\\/v) and hot air drying at 50–60°C was investigated. Approximately 1.5 log10 of Salmonella numbers was reduced after soaking the vegetables in acetic acid solution. The inhibitory effect of acetic acid on the bacteria was more pronounced during drying. The heat

Naphaporn Chiewchan; Pornpen Morakotjinda

2009-01-01

366

Power density enhancement of anion-exchange membrane-installed microbial fuel cell under bicarbonate-buffered cathode condition.  

PubMed

We introduce a high-performance microbial fuel cell (MFC) that was operated using a 0.1 M bicarbonate buffer as the cathodic electrolyte. The MFC had a 136.42 mW/m(2) maximum power density under continuous feeding of 5 mM acetate as fuel. Results of the electrode potential measurements showed that the cathode potential of the bicarbonate-buffered condition was higher than the phosphate-buffered condition, although the phosphate condition had less interfacial resistance between the membrane and electrolyte. Therefore, we posit here that the increased power of the bicarbonate-buffered MFC may be caused by the higher cathode potential rather than by the interfacial membrane-electrolyte resistance. PMID:23314365

Piao, Jingmei; An, Junyeong; Ha, Phuc Thi; Kim, Taeyoung; Jang, Jae Kyung; Moon, Hyunsoo; Chang, In Seop

2013-01-01

367

Effects of Environmental Parameters on the Formation and Turnover of Acetate by Forest Soils  

PubMed Central

The capacity to form acetate from endogenous matter was a common property of diverse forest soils when incubated under anaerobic conditions. At 15 to 20(deg)C, acetate synthesis occurred without appreciable delay when forest soils were incubated as buffered suspensions or in microcosms at various percentages of their maximum water holding capacity. Rates for acetate formation with soil suspensions ranged from 35 to 220 (mu)g of acetate per g (dry weight) of soil per 24 h, and maximal acetate concentrations obtained in soil suspensions were two- to threefold greater than those obtained with soil microcosms at the average water holding capacity of the soil. Cellobiose degradation in soil suspensions yielded H(inf2) as a transient product. Under anaerobic conditions, supplemental H(inf2) and CO(inf2) were directed towards the acetogenic synthesis of acetate, and enrichments yielded a syringate-H(inf2)-consuming acetogenic consortium. At in situ temperatures, acetate was a relatively stable anaerobic end product; however, extended incubation periods induced acetoclastic methanogenesis and sulfate reduction. Higher mesophilic and thermophilic temperatures greatly enhanced the capacity of soils to form methane. Although methanogenic and sulfate-reducing activities under in situ-relevant conditions were negligible, these findings nonetheless demonstrated the occurrence of methanogens and sulfate-reducing bacteria in these aerated terrestrial soils. In contrast to the protracted stability of acetate under anaerobic conditions at 15 to 20(deg)C with unsupplemented soils, acetate formed by forest soils was rapidly consumed in the presence of oxygen and nitrate, and substrate-product stoichiometries indicated that acetate turnover was coupled to oxygen-dependent respiration and denitrification. The collective results suggest that acetate formed under anaerobic conditions might constitute a trophic link between anaerobic and aerobic processes in forest soils.

Kusel, K.; Drake, H. L.

1995-01-01

368

Methanogenesis from acetate: enrichment studies.  

PubMed Central

An acetate enrichment culture was initiated by inoculating anaerobic sludge from a mesophilic methane digestor into a mineral salts medium with calcium acetate as the sole carbon and energy source. This enrichment was maintained indefinitely by weekly transfer into medium of the same composition. A study of this enrichment disclosed an unexpected age-dependent inhibition of methanogenesis by H2 and formate which apparently differed from the inhibition by chloroform and benzyl viologen. This age-dependent inhibition indicated that microbial interactions of the mixed enrichment population may play a regulatory role in methane formation. Futhermore, stimulation of methanogenesis in the acetate enrichment by addition of yeast extract showed a nutrient limitation which indicated that syntrophic interactions leading to formation of growth factors may also occur. A model is presented to illustrate the possible interrelationships between methanogenic and nonmethanogenic bacteria in their growth and formation of methane and carbon dioxide from acetate. Images

Baresi, L; Mah, R A; Ward, D M; Kaplan, I R

1978-01-01

369

Imidazole-buffered osmium tetroxide: an excellent stain for visualization of lipids in transmission electron microscopy  

Microsoft Academic Search

Summary  The usefulness of imidazole-buffered osmium tetroxide as a stain for lipids in transmission electron microscopy has been investigated. Rat liver and other tissues were fixed by perfusion with glutaraldehyde and post-fixed with osmium-imidazole and the appearance of lipid droplets was compared with that after post-fixation in unbuffered aqueous osmium tetroxide or an osmium solution buffered otherwise. Prominent electron-opaque staining of

Sabine Angermüller; H. Dariush Fahimi

1982-01-01

370

Matrix unit cell scheduler (MUCS) for input-buffered ATM switches  

Microsoft Academic Search

This paper presents a novel matrix unit cell scheduler (MUCS) for input-buffered asynchronous transfer mode (ATM) switches. The MUCS concept originates from a heuristic strategy that leads to an optimal solution for cell scheduling. Numerical analysis indicates that input-buffered ATM switches scheduled by MUCS can utilize nearly 100% of the available link bandwidth. A transistor-level MUCS circuit has been designed

Haoran Duan; John W. Lockwood; Sung Mo Kang

1998-01-01

371

Molecular Structure of Acetic acid  

NSDL National Science Digital Library

Acetic Acid commonly associated with vinegar; it is the most commercially important organic acid and is used to manufacture a wide range of chemical products, such as plastics and insecticides. Acetic acid is produced naturally by Aceto bacteria but, except for making vinegar, is usually made through synthetic processes. Ethanoic acid is used as herbicide, as a micro-biocide, as a fungicide and for pH adjustment.

2003-06-02

372

Acetate catabolism by Methanosarcina barkeri  

SciTech Connect

Cell suspensions of Methanosarcina barkeri convert the carboxyl and methyl group carbons of acetate to carbon dioxide and methane at pH 6 under an atmosphere of 100% CO/sub 2/. The rate of loss of radioactivity from (1-/sup 14/C)acetate was over three times greater than that from (2-/sup 14/C)acetate under these conditions. Control experiments with both labeled substrates present showed that the rates were additive. Addition of a high level of 2-bromoethanesulfonate to selectively inhibit methane formation largely inhibited release of /sup 14/C from methyl-labeled acetate but only marginally decreased the rate of loss from (1-/sup 14/C)acetate. Thus, in the absence of the inhibitor loss of /sup 14/C from (1-/sup 14/C)acetate likely reflects an isotopic exchange reaction with CO/sub 2/ superimposed on the overall conversion of acetate to CO/sub 2/ and CH/sub 4/. The exchange reaction was inhibited by uncouplers such as 2,4-dinitrophenol, CCCP, and FCCP. Cells permeabilized by treatment with nonionic detergents or disrupted by passage through a French pressure cell failed to catalyze the exchange reaction. Exchange activity was not restored by addition of ATP or by use of (1-/sup 14/C)acetyl CoA as substrate. No evidence for involvement of carbon monoxide dehydrogenase in the exchange was found in these experiments when CO/sub 2/ was replaced by CO. However, the soluble extracts retained the ability to convert acetate to methane in the presence of H/sub 2/ and ATP.

Grahame, D.A.

1987-05-01

373

Buffering Capacity of Crystalloid and Colloid Resuscitation Solutions.  

National Technical Information Service (NTIS)

Rapid loss of a critical blood volume is 100% fatal if not treated. After hemostasis, the rapid replacement of shed blood with volume is the only current treatment that provides survival. The method of replacement involves either crystalloid or colloid so...

L. W. Traverso F. Medina R. B. Bolin

1985-01-01

374

Cyanogen bromide cleavage of proteins in salt and buffer solutions.  

PubMed

Protocols for recombinant polypeptide production should provide high yields and be efficient, user friendly, and time saving. To perform cyanogen bromide (CNBr) cleavage of fusion proteins, the majority of researchers first desalted and vacuum-dried samples and then dissolved them in aqueous formic or trifluoroacetic acid. We propose to exclude the desalting step and run CNBr cleavage directly. We show that the commonly used Tris-HCl, sodium phosphate, NaCl, imidazole, and guanidine-HCl do not interfere with the reaction under acidic conditions. Omitting the desalting step does not decrease the final yields of target products, as demonstrated for fusion proteins of different origin and composition. PMID:20670609

Andreev, Yaroslav A; Kozlov, Sergey A; Vassilevski, Alexander A; Grishin, Eugene V

2010-07-27

375

Silver Nanoparticles in Cellulose Acetate Polymers: Rheological and Morphological Properties  

Microsoft Academic Search

Silver nitrate was incorporated in cellulose acetate with different substitution degrees as a dispersion medium. Silver-containing polymer solutions in 2-methoxyethanol were rheologically investigated, both before and after boiling, which permitted a better understanding of the morphological aspects of the corresponding cast films. The different distribution of the obtained silver nanoparticles in the polymer matrix, as well as the influence of

Adina Maria Necula; Iuliana Stoica; Niculae Olaru; Florica Doroftei; Silvia Ioan

2011-01-01

376

Eliminating Cell Broadband Engine™ DMA Buffer Overflows  

NASA Astrophysics Data System (ADS)

This paper presents effective and efficient implementation techniques for DMA buffer overflow elimination on the Cell Broadband Engine™ (Cell/B.E.) processor. In the Cell/B.E. programming model, application developers manually issue DMA commands to transfer data from the system memory to the local memories of the Cell/B.E. cores. Although this allows us to eliminate cache misses or cache invalidation overhead, it requires careful management of the buffer arrays for DMA in the application programs to prevent DMA buffer overflows. To guard against DMA buffer overflows, we introduced safe DMA handling functions for the applications to use. To improve and minimize the performance overhead of buffer overflow prevention, we used three different optimization techniques that take advantage of SIMD operations: branch-hint-based optimizations, jump-table-based optimizations and self-modifying-based optimizations. Our optimized implementation prevents all DMA buffer overflows with minimal performance overhead, only 2.93% average slowdown in comparison to code without the buffer overflow protection.

Murase, Masana

377

Buffer-regulated biocorrosion of pure magnesium.  

PubMed

Magnesium (Mg) alloys are being actively investigated as potential load-bearing orthopaedic implant materials due to their biodegradability in vivo. With Mg biomaterials at an early stage in their development, the screening of alloy compositions for their biodegradation rate, and hence biocompatibility, is reliant on cost-effective in vitro methods. The use of a buffer to control pH during in vitro biodegradation is recognised as critically important as this seeks to mimic pH control as it occurs naturally in vivo. The two different types of in vitro buffer system available are based on either (i) zwitterionic organic compounds or (ii) carbonate buffers within a partial-CO(2) atmosphere. This study investigated the influence of the buffering system itself on the in vitro corrosion of Mg. It was found that the less realistic zwitterion-based buffer did not form the same corrosion layers as the carbonate buffer, and was potentially affecting the behaviour of the hydrated oxide layer that forms on Mg in all aqueous environments. Consequently it was recommended that Mg in vitro experiments use the more biorealistic carbonate buffering system when possible. PMID:22190196

Kirkland, Nicholas T; Waterman, Jay; Birbilis, Nick; Dias, George; Woodfield, Tim B F; Hartshorn, Richard M; Staiger, Mark P

2011-12-22

378

Enhancement of the wet properties of transparent chitosan-acetic-acid-salt films using microfibrillated cellulose.  

PubMed

This report presents a new route to enhance the wet properties of chitosan-acetic-acid-salt films using microfibrillated cellulose (MFC). The enhancement makes it easier to form chitosan-acetic-acid-salt films into various shapes at room temperature in the wet state. Chitosan with MFC was compared with the well-known buffer treatment. It was observed that films containing 5 wt % MFC were visually identical to the buffered/unbuffered films without MFC. Field-emission scanning electron microscopy indicated that MFC formed a network with uniformly distributed fibrils and fibril bundles in the chitosan matrix. The addition of MFC reduced the risk of creases and deformation in the wet state because of a greater wet stiffness. The wet films containing MFC were also extensible. Although the stiffness, strength and extensibility were highest for the buffered films, the wet strength of the MFC-containing unbuffered films was sufficient for wet forming operations. The effects of MFC on the mechanical properties of the dry chitosan films were small or absent. It was concluded that the addition of MFC is an acceptable alternative to buffering for shaping chitosan films/products in the wet state. The advantages are that the "extra" processing step associated with buffering is unnecessary and that the film matrix remains more water-soluble. PMID:17645308

Nordqvist, David; Idermark, Johan; Hedenqvist, Mikael S; Gällstedt, Mikael; Ankerfors, Mikael; Lindström, Tom

2007-07-24

379

A New Fast Slew Buffering Algorithm Without Input Slew Assumptions  

Microsoft Academic Search

As VLSI technology moves to the nanoscale regime, an ultra-fast slew buffering technique to buffer large number of nets and minimize buffering cost is highly desirable. The existing method proposed in [1] is able to efficiently perform buffer insertion with a simplified assumption on buffer input slew, however, when handling more general cases without input slew assumptions, it becomes slow

Shiyan Hu; Jiang Hu

2007-01-01

380

Super Saturated Solution Lab Demo  

NSDL National Science Digital Library

This video from the Midwest Regional Center for Nanotechnology Education (NANO-LINK) demonstrates the growth of sodium acetate crystals. The brief video runs only 2:32 long and shows what happens when a small crystal of sodium acetate is added to a solution of super saturated sodium acetate. Each step of the experiment is clearly explained in the video so that it can easily be recreated.

2013-06-12

381

Investigation on isobaric vapor–liquid equilibrium for acetic acid + water + methyl ethyl ketone + isopropyl acetate  

Microsoft Academic Search

Isobaric vapor–liquid equilibrium (VLE) data for acetic acid+water, acetic acid+methyl ethyl ketone (MEK), MEK+isopropyl acetate, acetic acid+MEK+water and acetic acid+MEK+isopropyl acetate+water are measured at 101.33kPa using a modified Rose cell. The nonideal behavior in vapor phase of binary systems measured in this work is analyzed through calculating fugacity coefficients since mixture containing acetic acid deviates from ideal behavior seriously in

Qiang Xie; Hui Wan; MingJuan Han; GuoFeng Guan

2009-01-01

382

Borate buffer equilibria in nickel refining electrolytes  

Microsoft Academic Search

Buffer capacity studies, carried out using pH titrations, demonstrated that electrolytes containing NiSO4 + H3BO3 + Na2SO4 buffer more effectively than in the presence of H3BO3 + Na2SO4. The increased buffer capacity is dependent on the concentration of both Ni2+ and H3BO3. Thermodynamic analysis of the pH titration data suggested the formation of a weak complex, Ni(H2BO3)2, (logK ~ 3.8

B. V. Tilak; A. S. GENDRONt; M. A. Mosoiu

1977-01-01

383

Delignification of Bagasse with Acetic Acid and Ozone. II. Ozone Stage  

Microsoft Academic Search

Ozone gas was applied as second stage in delignification of bagasse pulp obtained with acetic acid. The kappa number was reduced from 44 to 10 with 3% ozone (based on dry pulp). Because bagasse was pulped with an aqueous solution of acetic acid (80% volume), selectivity of the ozone stage was favored and does not necessary acidulate pulp, which had

H. Contreras Q; Z. A. Nagieb; R. SanjuáN D

1997-01-01

384

Microbiological preservation of cucumbers for bulk storage by the use of acetic acid and food preservatives  

Technology Transfer Automated Retrieval System (TEKTRAN)

Microbial growth did not occur when cucumbers were preserved without a thermal process by storage in solutions containing acetic acid, sodium benzoate, and calcium chloride to maintain tissue firmness. The concentrations of acetic acid and sodium benzoate required to assure preservation were low en...

385

Simultaneous acetic acid separation and monosaccharide concentration by reverse osmosis.  

PubMed

This study aimed to investigate the feasibility and efficiency of simultaneous acetic acid separation and sugar concentration in model lignocellulosic hydrolyzates by reverse osmosis. The effects of operation parameters such as pH, temperature, pressure and feed concentration on the solute retentions were examined with a synthetic xylose–glucose–acetic acid model solution. Results showed that the monosaccharides were almost completely rejected at above 20 bar, while the acetic acid retention increased with the increase in pH and pressure, and decreased with the temperature increase. The maximum separation factors of acetic acid over xylose and glucose reached as high as 211.5 and 228.4 at pH 2.93 (the initial pH of model lignocellulosic hydrolyzates), 40 °C and 20 bar. Furthermore, the concentration and diafiltration process were employed at optimal operation conditions. Consequently, a high sugar concentration and a beneficially lower acetic acid concentration were simultaneously achieved by reverse osmosis. PMID:23376199

Zhou, Fanglei; Wang, Cunwen; Wei, Jiang

2013-01-03

386

Sodium acetate as a replacement for sodium bicarbonate in medical toxicology: a review.  

PubMed

Sodium bicarbonate is central to the treatment of many poisonings. When it was placed on the FDA drug shortage list in 2012, alternative treatment strategies to specific poisonings were considered. Many hospital pharmacies, poison centers, and medical toxicologists proposed sodium acetate as an adequate alternative, despite a paucity of data to support its use in medical toxicology. The intention of this review is to educate the clinician on the use of sodium acetate and to advise them on the potential adverse events when given in excess. We conducted a literature search focused on the pharmacology of sodium acetate, its use as a buffer in pathologic acidemia and dialysis baths, and potential adverse events associated with excess sodium acetate infusion. It appears safe to replace sodium bicarbonate infusion with sodium acetate on an equimolar basis. The metabolism of acetate, however, is more complex than bicarbonate. Future prospective studies will be needed to confirm the efficacy of sodium acetate in the treatment of the poisoned patient. PMID:23636658

Neavyn, Mark J; Boyer, Edward W; Bird, Steven B; Babu, Kavita M

2013-09-01

387

A Microprocessor ASCII Character Buffering System.  

National Technical Information Service (NTIS)

A microprocessor buffering system (MBS) was developed at the Environmental Monitoring and Support Laboratory -Cincinnati (EMSL-CI) to provide an efficient transfer for serial ASCII information between intelligent instrument systema and a Data General NOVA...

J. M. Teuschler R. A. Jollis J. E. Kopke

1982-01-01

388

TREATMENT OF AMMONIUM NITRATE SOLUTIONS  

DOEpatents

The treatment of waste solutions obtained in the processing of neutron- irradiated uranium containing fission products and ammonium nitrate is described. The object of this process is to provide a method whereby the ammonium nitrate is destroyed and removed from the solution so as to permit subsequent concentration of the solution.. In accordance with the process the residual nitrate solutions are treated with an excess of alkyl acid anhydride, such as acetic anhydride. Preferably, the residual nitrate solution is added to an excess of the acetic anhydride at such a rate that external heat is not required. The result of this operation is that the ammonium nitrate and acetic anhydride react to form N/sub 2/ O and acetic acid.

Boyer, T.W.; MacHutchin, J.G.; Yaffe, L.

1958-06-10

389

The use of static and dynamic physical property measurements to infer structural properties of associated liquids: Acetic acid-water  

Microsoft Academic Search

The anomalies which occur in most static and dynamic physical property measurements on solutions of water in acetic acid can be used with critical analysis to infer associative molecular structures. The anomalies indicate significant structural changes. Proton magnetic resonance chemical shifts for acetic acid-water solutions show a significant structural change occurring in the region of equal molar concentration. Literature values

Robert W. Sims; M. Robert Willicott III; R. R. Inners

1979-01-01

390

The use of static and dynamic physical property measurements to infer structural properties of associated liquids: Acetic acid–water  

Microsoft Academic Search

The anomalies which occur in most static and dynamic physical property measurements on solutions of water in acetic acid can be used with critical analysis to infer associative molecular structures. The anomalies indicate significant structural changes. Proton magnetic resonance chemical shifts for acetic acid–water solutions show a significant structural change occurring in the region of equal molar concentration. Literature values

Robert W. Sims; M. Robert Willicott III; R. R. Inners

1979-01-01

391

Temperature buffer test – design, instrumentation and measurements  

Microsoft Academic Search

The Temperature Buffer Test, TBT, is a heated full-scale field experiment carried out jointly by ANDRA and SKB at the SKB Äspö Hard Rock Laboratory in Southeast Sweden. An existing 8m deep, 1.8m diameter KBS-3-type deposition hole located at ?420m level has been selected for the test.The objectives are to improve the general understanding of Thermo-Hydro-Mechanical, THM, behavior of buffer

Torbjörn Sandén; Reza Goudarzi; Michel de Combarieu; Mattias Åkesson; Harald Hökmark

2007-01-01

392

Baroreflex Buffering and Susceptibility to Vasoactive Drugs  

Microsoft Academic Search

Background—The overall effect of vasoactive drugs on blood pressure is determined by a combination of the direct effect on vascular tone and an indirect baroreflex-mediated effect, a baroreflex buffering of blood pressure. Differences in baroreflex function affect the responsiveness to vasoactive medications, particularly baroreflex buffering of blood pressure; however, the magnitude is not known. Methods and Results—We characterized baroreflex function

Jens Jordan; Jens Tank; John R. Shannon; Andre Diedrich; Axel Lipp; Christoph Schröder; Guy Arnold; Arya M. Sharma; Italo Biaggioni; David Robertson; Friedrich C. Luft

393

32 taps digitally controlled buffered potentiometer  

Microsoft Academic Search

The paper presents a 32-tap digitally controlled buffered potentiometer designed in a 0.8 ?m CMOS process. An up\\/down counter determines which tap is connected to the output. Output settings are stored in nonvolatile memory. A rail-to-rail op amp is used as unity-gain buffer at the output in order to eliminate the errors given by the load

C. Stanescu; A. Tache; R. Iacob

2001-01-01

394

Comments on ``A Multiaccess Frame Buffer Architecture  

Microsoft Academic Search

D.T. Harper (see ibid., vol.43, no.10, p.618-22, 1994) introduced a storage scheme in a multiaccess frame buffer scenario and showed that the proposed architecture allows parallel access to constant area rectangles of the array of pixels stored in the frame buffer. These comments show that the claim may not be true. There are cases when parallel access is not possible

Bin Wei

1996-01-01

395

Implementing Virtual Buffer for Electric Power Grids  

Microsoft Academic Search

The electric power grid is a vital network for every aspect of our life. The lack of buffer between generation and consumption\\u000a makes the power grid unstable and fragile. While large scale power storage is not technically and economically feasible at\\u000a present stage, we argue that a virtual buffer could be effectively implemented through a demand side management strategy built

Rong Gao; Lefteri H. Tsoukalas

2007-01-01

396

REMOVAL OF ACETIC ACID IMPURITIES FROM ETHYL ACETATE BY ADSORPTION ON ION EXCHANGE RESINS  

Microsoft Academic Search

Removal of acetic acid impurities from ethyl acetate was attempted by sorption on basic ion-exchange resins. Kinetic studies showed that acid removal is controlled by intraparticle resistance from both ethyl acetate and alcohol. Breakthrough curves for uptake of the acid from ethyl acetate were obtained at different flow rates and concentrations. Desorption studies were performed using both ethyl acetate and

H. M. Anasthas; V. G. Gaikar

2001-01-01

397

Infinitely selective repair buffer for EUVL reticles  

NASA Astrophysics Data System (ADS)

The three-layer absorber stack for EUVL reticles currently consists of an absorber, repair buffer and etch stop layers. The repair buffer should exhibit high etch selectivity during the absorber etch processes (i.e. pattern transfer and focused ion beam (FIB) repair), be thermally and electrically conductive, optimally thin and have high etch selectivity to the silicon-capping layer over the Mo/Si multi-layer mirror. The absorber materials that have been studied in the past are TaSiN and Cr with SiON as the repair buffer on top of a Cr etch stop layer. The SiON repair buffer is insulating, exhibiting low thermal and electrical conductivity. Also, the required thickness for FIB repair is greater than 750 Angstroms using a standard 30-keV Ga+ FIB tool, while the etch selectivity to the silicon capping layer during pattern transfer is less than five to one necessitating a Cr etch stop. A sputtered carbon repair buffer exhibiting the required qualities has been studied. The carbon film is thermally and electrically conductive and exhibits extremely high reactive ion etch selectivity to the silicon-capping layer. Carbon also has the lowest sputter yield out of all the elements opening a larger FIB repair process window without using gas-assisted etching. A conductive repair buffer also prevents the possibility of static charge buildup on the mask that could damage patterns during an electrostatic discharge.

Wasson, James R.; Smith, Ken H.; Mangat, Pawitter J.; Hector, Scott D.

2001-08-01

398

Formation of Amino Acids from Reactor Irradiated Ammonium Acetate  

NASA Astrophysics Data System (ADS)

Ammonium acetate in various conditions was irradiated in a reactor to examine the contributions of both the reactor radiations and recoiled14C nucleis to form the biologically interesting molecules. Present investigations demonstrated that several amino acids, glycine, alanine, ?-alanine and GABA, and may-be aspartic acid, serine and valine by prolonged irradiation, were formed in the aqueous solutions of ammonium acetate.14C-radioactivities were also found distributed in these amino acids. However, no special relationship between14C-radioactivity and these amino acids formed was observed.

Akaboshi, M.; Kawai, K.; Maki, H.; Kawamoto, K.; Honda, Y.

1982-12-01

399

A Simple Way to Pattern Mn_12-acetate Thin Films  

NASA Astrophysics Data System (ADS)

We have observed that Mn_12-acetate ([Mn_12O_12(CH_3COO)_16(H_2O)_4]ot2CH_3COOHot4H_2O) molecules, dissolved in organic solvents, can be self-assembled along the edge of the Mn_12 solution droplet on a Si/SiO2 substrate as the solvent is evaporated. This phenomenon may be related to the well known "coffee-stain effect"”, which leads to a dense particulate deposit along the edge of a drying droplet of coffee on a solid surface. In our study, we have observed such a deposit of Mn_12-acetate at the perimeter of a droplet, after a dilute solution in various organic solvents has been dried. We investigated how the deposits depend on the evaporation rate. Also, we controlled the concentration of the solution to find its relation to the resulting pattern deposit. By patterning the surface with resist and performing a lift-off we created what are, to our knowledge, the first artificial patterns of Mn_12-acetate. This may allow for convenient thin film devices of Mn_12-acetate and work in this direction is ongoing. This work was supported by the Texas Higher Education Coordinating Board and Texas A University.

Kim, K.; Seo, D. M.; Means, J.; Viswanathan, M.; Teizer, W.

2004-03-01

400

Variability of acid-base status in acetate-free biofiltration 84% versus bicarbonate dialysis.  

PubMed

The ultimate goal of hemodialysis (HD) treatment is to achieve the highest level of efficacy in the presence of maximal clinical tolerance. With an aim to offer good hemodynamic stability, as observed during the acetate-free biofiltration 14% (AFB 14%) to patients who are intolerant to bicarbonate dialysis (BD) and with less cost, we have developed since June 1994, a new HD technique, namely AFB 84%. This study was carried out to analyze acid-base variations during the AFB 84% in comparison to BD in hemodynamically stable patients on regular HD. This was a prospective randomized crossover study carried out on 12 patients (6 males and 6 females) for a total of 144 HD sessions (72 BD and 72 AFB 84%). Patients with decompensated cardiomyopathy, respiratory diseases or uncontrolled hypertension were not included in the trial. All the patients were treated with BD or AFB 84%; the latter is characterized by the absence of acetate in the dialysate and a complete correction of buffer balance by post-dilutional infusion of bicarbonate-based replacement solution. The comparison of pre-dialysis arterial acid-base and blood-gas parameters revealed no significant differences of pH, HCO(3)(-) and paCO(2) levels between the two techniques. Analysis of post-dialysis parameters showed that, among patients dialyzed with BD, there was over correction of metabolic acidosis with a tendency towards metabolic alkalosis. In contrast, in patients dialyzed with AFB 84%, we observed a significant improvement in pH and HCO(3)(-) levels but the increase in paCO(2) level was not significant. A comparison of these parameters between the two techniques showed statistically significant difference in pH, HCO(3)(-) and paCO(2) levels, but not for paO(2) level. AFB 84% can offer some important advantages with the complete absence of acetate from the substitution fluids, and permits a better correction of metabolic acidosis than BD, without causing alkalosis. PMID:18310870

Harzallah, Kais; Hichri, Nourredine; Mazigh, Chakib; Tagorti, Mohamed; Hmida, Ahmed; Hmida, Jalel

2008-03-01

401

Specification, Selectivity, and Performance of Porous Cellulose Acetate Membranes in Reverse Osmosis.  

National Technical Information Service (NTIS)

The general specifications of the Loeb-Sourirajan type porous cellulose acetate membranes are given in terms of the pure water permeability constant, A, and the solute transport parameter for sodium chloride at different operating pressures. A scale of me...

J. P. Agrawal S. Sourirajan

1969-01-01

402

Inhibition of Ice Growth and Recrystallization by Zirconium Acetate and Zirconium Acetate Hydroxide  

PubMed Central

The control over ice crystal growth, melting, and shaping is important in a variety of fields, including cell and food preservation and ice templating for the production of composite materials. Control over ice growth remains a challenge in industry, and the demand for new cryoprotectants is high. Naturally occurring cryoprotectants, such as antifreeze proteins (AFPs), present one solution for modulating ice crystal growth; however, the production of AFPs is expensive and inefficient. These obstacles can be overcome by identifying synthetic substitutes with similar AFP properties. Zirconium acetate (ZRA) was recently found to induce the formation of hexagonal cavities in materials prepared by ice templating. Here, we continue this line of study and examine the effects of ZRA and a related compound, zirconium acetate hydroxide (ZRAH), on ice growth, shaping, and recrystallization. We found that the growth rate of ice crystals was significantly reduced in the presence of ZRA and ZRAH, and that solutions containing these compounds display a small degree of thermal hysteresis, depending on the solution pH. The compounds were found to inhibit recrystallization in a manner similar to that observed in the presence of AFPs. The favorable properties of ZRA and ZRAH suggest tremendous potential utility in industrial applications.

Mizrahy, Ortal; Bar-Dolev, Maya; Guy, Shlomit; Braslavsky, Ido

2013-01-01

403

Anion buffering in the internal electrolyte resulting in extended durability of phosphate-selective electrodes.  

PubMed

The decomposition of the ionophore uranyl salophene in a polymeric membrane is the main source of the deterioration of phosphate-selective electrodes in time. Due to the efficient buffering of both phosphate and uranyl ions in the internal electrolyte solution, a significant decrease of the rate of decomposition of uranyl salophene in the membrane was observed, improving the lifetime of phosphate-selective electrodes. The most efficient buffering of such ions, resulting in the best sensor durability, was obtained using the internal electrolyte solution containing barium-uranyl phosphate mineral, meta-uranocircite II. PMID:12964780

Wojciechowski, Kamil; Wróblewski, Wojciech; Brzózka, Zbigniew

2003-07-01

404

Stability and tribological performances of fluid phospholipid bilayers: Effect of buffer and ions  

Microsoft Academic Search

We have investigated the mechanical and tribological properties of supported Dioleoyl phosphatidylcholine (DOPC) bilayers in different solutions: ultrapure water (pH 5.5), saline solution (150mM NaCl, pH 5.8), Tris buffer (pH 7.2) and Tris saline buffer (150mM NaCl, pH 7.2). Friction forces are measured using a homemade biotribometer. Lipid bilayer degradation is controlled in situ during friction tests using fluorescence microscopy.

F. Dekkiche; M. C. Corneci; A.-M. Trunfio-Sfarghiu; B. Munteanu; Y. Berthier; W. Kaabar; J.-P. Rieu

2010-01-01

405

Effect of Organic Acid Additions on the General and Localized Corrosion Susceptibility of Alloy 22 in Chloride Solutions  

SciTech Connect

Electrochemical studies such as cyclic potentiodynamic polarization (CPP) and electrochemical impedance spectroscopy (EIS) were performed to determine the corrosion behavior of Alloy 22 (N06022) in 1M NaCl solutions at various pH values from acidic to neutral at 90 C. All the tested material was wrought Mill Annealed (MA). Tests were also performed in NaCl solutions containing weak organic acids such as oxalic, acetic, citric and picric. Results show that the corrosion rate of Alloy 22 was significantly higher in solutions containing oxalic acid than in solutions of pure NaCl at the same pH. Citric and picric acids showed a slightly higher corrosion rate, and acetic acid maintained the corrosion rate of pure chloride solutions at the same pH. Organic acids revealed to be weak inhibitors for crevice corrosion. Higher concentration ratios, compared to nitrate ions, were needed to completely inhibit crevice corrosion in chloride solutions. Results are discussed considering acid dissociation constants, buffer capacity and complex formation constants of the different weak acids.

Carranza, R M; Giordano, C M; Rodr?guez, M A; Ilevbare, G O; Rebak, R B

2007-08-28

406

Temperature buffer test design, instrumentation and measurements  

NASA Astrophysics Data System (ADS)

The Temperature Buffer Test, TBT, is a heated full-scale field experiment carried out jointly by ANDRA and SKB at the SKB Äspö Hard Rock Laboratory in Southeast Sweden. An existing 8 m deep, 1.8 m diameter KBS-3-type deposition hole located at -420 m level has been selected for the test. The objectives are to improve the general understanding of Thermo-Hydro-Mechanical, THM, behavior of buffer materials submitted to severe thermal conditions with temperatures well over 100 °Cduring water uptake of partly saturated bentonite-based buffer materials,and to check, in due time, their properties after water saturation. The test includes two carbon steel heating canisters each 3 m high and 0.6 m diameter, surrounded by 0.6 m of buffer material. There is a 0.2 m thick sand shield between the upper heater and the surrounding bentonite, while the lower heater is surrounded by bentonite only. On top of the stack of bentonite blocks is a confining plug anchored to the rock. In the slot between buffer and rock wall is a sand filter equipped with pipes to control the water pressure at the boundary, which is seldom done with an EBS in situ experiment. Both heater mid-height planes are densely instrumented in order to follow, with direct or indirect methods, buffer THM evolution. Temperature, relative humidity, stress and pore pressure have been monitored since the test start in March 2003. Total water inflow is also monitored. Firstly, the present paper describes the test design, the instrumentation, the plug anchoring system and the system for water boundary pressure control. Second, having described the test, the paper shows different measurements that illustrate evolution of temperature, saturation, suction and swelling pressure in the upper and the lower buffer.

Sandén, Torbjörn; Goudarzi, Reza; de Combarieu, Michel; Åkesson, Mattias; Hökmark, Harald

407

Indole3-acetic Acid Sensitization of Phytochrome-Controlled Growth of Coleoptile Sections  

Microsoft Academic Search

Addition of 6 mu M indole-3-acetic acid (IAA) to incubation buffer increases the sensitivity of coleoptile sections cut from dark-grown Avena sativa L. cv. Lodi to red light by a factor of 10,000, relative to the response in the absence of added IAA, without changing the maximum amount of light-induced growth. From 0.03 to 4 mu M IAA sections show

James R. Shinkle; Winslow R. Briggs

1984-01-01

408

Redox buffered hydrofluoric acid etchant for the reduction of galvanic attack during release etching of MEMS devices having noble material films  

DOEpatents

Etchant solutions comprising a redox buffer can be used during the release etch step to reduce damage to the structural layers of a MEMS device that has noble material films. A preferred redox buffer comprises a soluble thiophosphoric acid, ester, or salt that maintains the electrochemical potential of the etchant solution at a level that prevents oxidation of the structural material. Therefore, the redox buffer preferentially oxidizes in place of the structural material. The sacrificial redox buffer thereby protects the exposed structural layers while permitting the dissolution of sacrificial oxide layers during the release etch.

Hankins, Matthew G. (Albuquerque, NM)

2009-10-06

409

Buffer Standards for the Physiological pH of the Zwitterionic Compound, DIPSO from 5 to 55 degrees C.  

PubMed

The values of the second dissociation constant, pK(2), and related thermodynamic quantities of 3-[N,N-bis (2-hydroxyethyl)amino]-2-hydroxypropanesulfonic acid (DIPSO) have already been reported over the temperature range 5 to 55 degrees C including 37 degrees C. This paper reports the pH values of four NaCl-free buffer solutions and four buffer composition containing NaCl salt at I = 0.16 mol.kg(-1). Conventional pa(H) values are reported for all eight buffer solutions. The operational pH values have been calculated for four buffer solutions recommended as pH standards, at 25 and 37 degrees C after correcting the liquid junction potentials with the flowing junction cell. PMID:20160870

Roy, Lakshmi N; Roy, Rabindra N; Lenoue, Sean R; Denton, Cole E; Fuge, Michael S; Dunseth, Craig D; Roy, Chandra N; Hayden, Shawn M; Wollen, Joshua T; Sreepada, Kripa

2009-04-01

410

Buffer Standards for the Physiological pH of the Zwitterionic Compound, DIPSO from 5 to 55?C  

PubMed Central

The values of the second dissociation constant, pK2, and related thermodynamic quantities of 3-[N,N-bis (2-hydroxyethyl)amino]-2-hydroxypropanesulfonic acid (DIPSO) have already been reported over the temperature range 5 to 55°C including 37°C. This paper reports the pH values of four NaCl-free buffer solutions and four buffer composition containing NaCl salt at I = 0.16 mol·kg?1. Conventional paH values are reported for all eight buffer solutions. The operational pH values have been calculated for four buffer solutions recommended as pH standards, at 25 and 37°C after correcting the liquid junction potentials with the flowing junction cell.

Roy, Lakshmi N.; Roy, Rabindra N.; LeNoue, Sean R.; Denton, Cole E.; Fuge, Michael S.; Dunseth, Craig D.; Roy, Chandra N.; Hayden, Shawn M.; Wollen, Joshua T.; Sreepada, Kripa

2009-01-01

411

Acetate and Formate Stress: Opposite Responses in the Proteome of Escherichia coli  

PubMed Central

Acetate and formate are major fermentation products of Escherichia coli. Below pH 7, the balance shifts to lactate; an oversupply of acetate or formate retards growth. E. coli W3110 was grown with aeration in potassium-modified Luria broth buffered at pH 6.7 in the presence or absence of added acetate or formate, and the protein profiles were compared by two-dimensional sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Acetate increased the steady-state expression levels of 37 proteins, including periplasmic transporters for amino acids and peptides (ArtI, FliY, OppA, and ProX), metabolic enzymes (YfiD and GatY), the RpoS growth phase regulon, and the autoinducer synthesis protein LuxS. Acetate repressed 17 proteins, among them phosphotransferase (Pta). An ackA-pta deletion, which nearly eliminates interconversion between acetate and acetyl-coenzyme A (acetyl-CoA), led to elevated basal levels of 16 of the acetate-inducible proteins, including the RpoS regulon. Consistent with RpoS activation, the ackA-pta strain also showed constitutive extreme-acid resistance. Formate, however, repressed 10 of the acetate-inducible proteins, including the RpoS regulon. Ten of the proteins with elevated basal levels in the ackA-pta strain were repressed by growth of the mutant with formate; thus, the formate response took precedence over the loss of the ackA-pta pathway. The similar effects of exogenous acetate and the ackA-pta deletion, and the opposite effect of formate, could have several causes; one possibility is that the excess buildup of acetyl-CoA upregulates stress proteins but excess formate depletes acetyl-CoA and downregulates these proteins.

Kirkpatrick, Christopher; Maurer, Lisa M.; Oyelakin, Nikki E.; Yoncheva, Yuliya N.; Maurer, Russell; Slonczewski, Joan L.

2001-01-01

412

The Effect of Carbon Dioxide Concentration and Buffer System on Nitrate and Nitrite Assimilation by Dunaliella tertiolecta  

Microsoft Academic Search

SUMMARY Dunaliella tertiolecta required carbon dioxide in substrate concentrations (1.75 %, v\\/v) to assimilate either nitrate or nitrite at maximum rates in light. The addition of glucose, glycerol, acetate, pyruvate or a-ketoglutarate did not remove the requirement for carbon dioxide. The rates of nitrate and nitrite assimilation in light depended upon the buffer system used. The lowest rates of nitrate

B. R. GRANT

1968-01-01

413

Thin La{sub 2}Zr{sub 2}O{sub 7} films made from a water-based solution  

SciTech Connect

Thin films of La{sub 2}Zr{sub 2}O{sub 7} (LZO) are highly regarded as possible buffer layers in the coated conductor configuration. This report describes a new synthesis for thin crystalline LZO films, based on a largely water-based solution, mainly containing metal acetates, acetic acid and an organic amine-base: triethanolamine. Initially, a thin layer of amorphous material is deposited on the textured Ni-5 at%W substrate by means of dip-coating. Only by careful control of the thermal treatment can the layer be transformed into a crystalline layer. Important parameters in this respect are the heating rate and the dwell time. The amorphous gel is analysed by HR-TGA/DTA and HR-TEM. The textured layers are analysed by XRD, pole figures, RHEED, AFM and SEM. - Grapical Abstract: Thin films of La2Zr2O7 (LZO) are produced via a water-based solution, containing metal acetates, acetic acid and triethanolamine. The thin layer is deposited on the textured Ni-5 at%W substrate by dip-coating. The amorphous gel is analysed by HR-TGA/DTA and HR-TEM. The textured layers are analysed by XRD, pole figures, RHEED analysis, AFM and SEM.

Cloet, V. [Ghent University, Krijgslaan 281-S3, 9000 Gent (Belgium)], E-mail: veerle.cloet@ugent.be; Feys, J. [Ghent University, Krijgslaan 281-S3, 9000 Gent (Belgium); Huehne, R. [Institute for Metallic Materials, IFW Dresden, Helmholtzstrasse 20, 01069 Dresden (Germany); Hoste, S.; Van Driessche, I. [Ghent University, Krijgslaan 281-S3, 9000 Gent (Belgium)

2009-01-15

414

Titanium (IV)Improved H2O2\\/O3 Process for Acetic Acid Degradation under Acid Conditions  

Microsoft Academic Search

The effect of Ti(IV) on the degradation efficiency of acetic acid by O3\\/H2O2 was investigated. The removal rate of acetic acid by O3\\/H2O2 increased from 8.0% to 62.9% after 30 min when Ti(IV) was added to acetic acid solution at pH 2.8. The optimized parameters were as follows: the pH of acetic acid solution less than 5.0; the mass concentration

Shao-Ping Tong; Wen-wen Li; Shu-qin Zhao; Chun-an Ma

2011-01-01

415

Carbopols as factors buffering triethanolamine interacting with artificial skin sebum.  

PubMed

Triethanolamine is an ethanolamine applied as counter-ion for fatty acid soaps. Interaction between triethanolamine and free fatty acids is suggested to be useful for cleansing sebaceous follicles in acne prevention. Considering relatively high pH of aqueous triethanolamine solutions we investigated influence of different concentrations of anionic polymers--Carbopol 934P, Carbopol 974P and Carbopol 980 on pH, rheological behavior and, most of them, intensity of triethanolamine interaction with artificial skin sebum components. Triethanolamine buffered using Carbopols influenced artificial skin sebum. Intensity of this interaction was measured applying specific optical method. Penetration of triethanolamine into artificial sebum and its uplift induced by above mentioned interaction were measured. Respective penetration rates and uplift rates were calculated. We found significant differences between Carbopols. The values of the penetration rates amounted 2.94 x 10(-04) h(-1) to 4.12 x 10(-03) h(-1), whereas rates for the uplift process were from 1.97 x 10(-04) h(-1) to 3.28 x 10(-03) h(-1). The value of pH is reduced from 10.06 for pure 0.1 M aqueous triethanolamine solution to 7.67 with the increase of polymer to triethanolamine molar ratio in the preparations. It is considered that triethanolamin buffered with acrylic acid polymers--Carbopols could influence cleansing of pilosebaceous unit follicles and contribute to acne prevention. PMID:15850295

Musia?, Witold; Kubis, Aleksander

2004-01-01

416

Undergraduate Chemistry Students' Perceptions of and Misconceptions about Buffers and Buffer Problems  

ERIC Educational Resources Information Center

|Both upper- and lower-level chemistry students struggle with understanding the concept of buffers and with solving corresponding buffer problems. While it might be reasonable to expect general chemistry students to struggle with this abstract concept, it is surprising that upper-level students in analytical chemistry and biochemistry continue to…

Orgill, MaryKay; Sutherland, Aynsley

2008-01-01

417

A buffer-regulated HF acid for sandstone acidizing to 550/sup 0/F  

SciTech Connect

Two earlier papers discussed the suitability of bugger-regulated HF acid (BRHFA) for high-temperature sandstone matrix stimulation treatments. Acetic-acid/acetate buffering (pH = 4.5 to 5.0) limited corrosion to acceptable levels at temperatures up to about 350/sup 0/F (177/sup 0/C). Subsequent development of reservoirs with temperatures approaching 450/sup 0/F (232/sup 0/C) demonstrated a need for even higher-temperature acidizing systems. This paper discusses a new, less corrosive BRHFA formulation that has clay-dissolving capacity comparable to 7 1/2% HCl/1 1/2% HF acid. The corrosion rate of carbon steel at 550/sup 0/F (288/sup 0/C) is only 330 mils/yr (8.4 mm/a). The BRHFA systems are also compatible with a variety of corrosion-resistant alloys. This paper presents clay slurry, core flow, and corrosion data and discusses use guidelines.

Scheuerman, R.F.

1988-02-01

418

[The effect of silymarin-N-methylglucamine salt and silybin-dihemisuccinate on (1-14C)-acetate incorporation in rat liver lipids (author's transl)].  

PubMed

60 min after i.v. application of 140.5 mg silymarin-N-methylglucamine salt/kg body weight dissolved in 4% polyvinylpyrrolidone solution, and 30 min after i.p. administration [1-14C]-acetate, compared to rats treated with solvent only, a statistically significant increase of specific radioactivities in total lipids, triglycerides, total phospholipids as well as in the phosphatidylcholine fraction and a decrease of specific activities in the free cholesterol fraction of the liver can be determined. 70 min after i.p. application of 140.5 mg silybin-dihemisuccinate/kg body weight dissolved in phosphate buffer, and 10 min after i.v. administration of [1-14C]-acetate in comparison with rats treated with solvent only, a statistically significant enhancement of specific activities of total liver lipids, free hepatic cholesterol, liver triglycerides, total liver phospholipids, and the hepatic fraction of phosphatidyl ethanolamine can be measured. Silybin also produces an increased specific radioactivity of the serum triglyceride fraction. PMID:947204

Schriewer, H; Rauen, H M

1976-02-01

419

Labview virtual instruments for calcium buffer calculations.  

PubMed

Labview VIs based upon the calculator programs of Fabiato and Fabiato (J. Physiol. Paris 75 (1979) 463) are presented. The VIs comprise the necessary computations for the accurate preparation of multiple-metal buffers, for the back-calculation of buffer composition given known free metal concentrations and stability constants used, for the determination of free concentrations from a given buffer composition, and for the determination of apparent stability constants from absolute constants. As implemented, the VIs can concurrently account for up to three divalent metals, two monovalent metals and four ligands thereof, and the modular design of the VIs facilitates further extension of their capacity. As Labview VIs are inherently graphical, these VIs may serve as useful templates for those wishing to adapt this software to other platforms. PMID:12468127

Reitz, Frederick B; Pollack, Gerald H

2003-01-01

420

Schemes for Implementing Buffer Sharing in Continuous-Media Systems  

Microsoft Academic Search

Buffer management in continuous-media systems is a frequently studied topic. One ofthe most interesting recent proposals is the idea of buffer sharing for concurrent streams. As analyzedin [6], by taking advantage of the temporal behaviour of concurrent streams, buffer sharing can leadto a 50% savings in total buffer space. In this paper, we study how to actually implement buffersharing. To

Dwight J. Makaroff; Raymond T. Ng

1995-01-01

421

Distributed scheduling based on due dates and buffer prioritization  

Microsoft Academic Search

The problem of scheduling a semiconductor manufacturing facility is addressed. Several buffer priority and due-date based scheduling policies for nonacyclic flow lines are studied. Not all buffer priority policies are stable, as is shown by a counterexample. However, the first buffer first serve and last buffer first serve policies are stable. Also, the earliest due data and least-slack policies are

C.-H. Lu; P. R. Kumar

1990-01-01

422

Biofiltration of ethyl acetate and amyl acetate using a composite bead biofilter.  

PubMed

Biodegradation kinetic behaviors of ethyl acetate and amyl acetate in a composite bead biofilter were investigated. The composite bead was the spherical PVA/peat/KNO3/GAC composite bead which was prepared in our previous works. Both microbial growth rate and biochemical reaction rate were inhibited at higher inlet concentration. For the microbial growth process, the microbial growth rate of ethyl acetate was greater than that of amyl acetate in the inlet concentration range of 100-400ppm. The degree of inhibitive effect was almost the same for ethyl acetate and amyl acetate in this concentration range. The half-saturation constant Ks values of ethyl acetate and amyl acetate were 16.26 and 12.65ppm, respectively. The maximum reaction rate Vm values of ethyl acetate and amyl acetate were 4.08 and 3.53gCh(-1)kg(-1) packed material, respectively. Zero-order kinetic with the diffusion limitation could be regarded as the most adequate biochemical reaction model. For the biochemical reaction process, the biochemical reaction rate of ethyl acetate was greater than that of amyl acetate in the inlet concentration range of 100-400ppm. The inhibitive effect for ethyl acetate was more pronounced than that for AA in this concentration range. The maximum elimination capacity of ethyl acetate and amyl acetate were 82.3 and 37.93gCh(-1)m(-3) bed volume, respectively. Ethyl acetate degraded by microbial was easier than amyl acetate did. PMID:18445522

Chan, Wu-Chung; Su, Mei-Qi

2008-04-28

423

MINIRIN Desmopressin acetate 1. EXECUTIVE SUMMARY ..... ...  

Center for Biologics Evaluation and Research (CBER)

Text Version... Brand Name MINIRIN Generic Name Desmopressin acetate ... NDA 21795 MINIRIN (desmopressin acetate) 0.1 mg and 0.2 mg Tablets Page 1 of 30 ... More results from www.fda.gov/downloads/advisorycommittees/committeesmeetingmaterials

424

Combined effect of acetate and reduced water activity in survival of Salmonella typhimurium 7136.  

PubMed Central

Whereas Salmonella typhimurium 7136 will not grow at reduced water activity (aw), it was survival in such items as intermediate-moisture foods is of interest. Initial studies demonstrated that the addition of 0.3 M acetate (pH 4.7) to glycerol-Trypticase soy broth (BBL Microbiology Systems) solutions (aw 0.86) reduced the viability of S. typhimurium cells. The extent of death of cells exposed to reduced aw was increased by decreasing the pH or increasing the concentration of acetate. Acidification of glycerol-Trypticase soy broth reduced the D40 degrees C value exhibited by cells exposed to a range of aw solutions (0.65 to 0.92). Acetate appeared to affect survival more dramatically as aw values approached the minimum growth limit. Acidification with acetate also reduced cell survival in a variety of humectant solutions with an aw of 0.86 (glycerol, dextrose, and NaCl).

Meyer, L B; Martin, S E; Witter, L D

1981-01-01

425

Characterization of the spherical intermediates and fibril formation of hCT in HEPES solution using solid-state (13)C-NMR and transmission electron microscopy.  

PubMed

Human calcitonin (hCT) is a 32-amino acid peptide hormone that contains an intrachain disulfide bridge between Cys1 and Cys7 and a proline amide at the C-terminus. hCT tends to associate to form a fibril precipitate of the same type as amyloid fibrils, and hence has been studied as a model of amyloid fibril formation. The fibrillation process in N-(2-hydroxyethyl)piperazine-N'-2-ethanesulfonic acid (HEPES) solution was examined using transmission electron microscopy. The rate of hCT fibrillation in HEPES solution was much lower than in phosphate buffer and acetic acid solution. Spherical intermediate aggregates (nuclei) were observed during the early stage of fibril formation. Short proto-fibrils appeared on the surface of the spherical intermediates. Subsequently, the spherical intermediates transformed directly into long proto-fibrils, which then elongated into mature hCT fibrils. The fibrillation process was also examined using solid-state (13)C-NMR spectroscopy, which indicated that the fibril structure was a ?-sheet in the central region and a mixture of random coils and ?-sheets at the C-terminus. The kinetics of fibril formation was examined in terms of a two-step autocatalytic reaction mechanism. The first-step nucleation rate (k1) was lower in HEPES solution than in phosphate buffer and acetic acid solution because the half-life of the intermediates is significantly longer in HEPES solution. In contrast, the second-step fibril elongation rate (k2) was similar in HEPES solution and acidic solutions. Specific interaction of HEPES molecules with hCT may stabilize the spherical intermediates and consequently inhibit the fibril elongation process of hCT. PMID:24002168

Itoh-Watanabe, Hikari; Kamihira-Ishijima, Miya; Kawamura, Izuru; Kondoh, Masashi; Nakakoshi, Masamichi; Sato, Michio; Naito, Akira

2013-09-04

426

Preparation of Buffers. An Experiment for Quantitative Analysis Laboratory  

NASA Astrophysics Data System (ADS)

In our experience, students who have a solid grounding in the theoretical aspects of buffers, buffer preparation, and buffering capacity are often at a loss when required to actually prepare a buffer in a research setting. However, there are very few published laboratory experiments pertaining to buffers. This laboratory experiment for the undergraduate quantitative analysis lab gives students hands-on experience in the preparation of buffers. By preparing a buffer to a randomly chosen pH value and comparing the theoretical pH to the actual pH, students apply their theoretical understanding of the Henderson-Hasselbalch equation, activity coefficients, and the effect of adding acid or base to a buffer. This experiment gives students experience in buffer preparation for research situations and helps them in advanced courses such as biochemistry where a fundamental knowledge of buffer systems is essential.

Buckley, P. T.

2001-10-01

427

Conductance of HCl, NaCl, Na acetate, and acetic acid in water-ethylene carbonate solvent mixtures at 25 and 40°C  

Microsoft Academic Search

The molar conductances of solutions of hydrochloric acid, sodium chloride, sodium acetate, and acetic acid were measured in water-ethylene carbonate (EC) solvent mixtures at 25 and 40°C. These solvents have dielectric constants higher than that of water. Four solvent compositions, in which the mole fraction (x2) of EC was 0.2, 0.4, 0.5, and 0.6, were studied at 25°C. For HCl

Barry R. Boerner; Roger G. Bates

1978-01-01

428

Grass buffers for playas in agricultural landscapes: an annotated bibliography  

USGS Publications Warehouse

This bibliography and associated literature synthesis (Melcher and Skagen, 2005) was developed for the Playa Lakes Joint Venture (PLJV). The PLJV sought compilation and annotation of the literature on grass buffers for protecting playas from runoff containing sediments, nutrients, pesticides, and other contaminants. In addition, PLJV sought information regarding the extent to which buffers may attenuate the precipitation runoff needed to fill playas, and avian use of buffers. We emphasize grass buffers, but we also provide information on other buffer types.

Melcher, Cynthia P.; Skagen, Susan K.

2005-01-01

429

Performance Analysis of Buffering Schemes on Wormhole Routers  

Microsoft Academic Search

Wormhole switched input-buffered and middle-buffered routers with virtual channels are analyzed in this paper. Middle buffering refers to the placement of virtual channels between the demultiplexers and multiplexers of a crossbar switch. An analytical model for multistage interconnection networks using middle-buffered switches is developed. In addition, extensive simulation is conducted to assess the performance of the two buffering techniques in

Younes M. Boura; Chita R. Das

1997-01-01

430

Changes in red blood cell volume on fixation in glutaraldehyde solutions  

Microsoft Academic Search

Light scattering (nephelometry) was used to determine directly the change in volume of red blood cells immersed in a variety of buffer and fixative solutions. Cells immersed in saline or phosphate buffer solutions showed a change in volume that reflected the osmolarity of the solution, shrinkage taking place in hypertonic solutions and swelling and haemolysis occurring in strongly hypotonic solutions.

Christopher A. Squier; John S. Hart; Alan Churchland

1976-01-01

431

Asparagine deamidation dependence on buffer type, pH, and temperature.  

PubMed

The deamidation of asparagine into aspartate and isoaspartate moieties is a major pathway for the chemical degradation of monoclonal antibodies (mAbs). It can affect the shelf life of a therapeutic antibody that is not formulated or stored appropriately. A new approach to detect deamidation using ion exchange chromatography was developed that separates papain-digested mAbs into Fc and Fab fragments. From this, deamidation rates of each fragment can be calculated. To generate kinetic parameters useful in setting shelf life, buffers prepared at room temperature and then placed at the appropriate stability temperatures. Solution pH was not adjusted to the same at different temperatures. Deamidation rate at 40°C was faster in acidic buffers than in basic buffers. However, this trend is reversed at 5°C, attributed to the change in hydroxide ion concentration influenced by buffer and temperature. The apparent activation energy was higher for rates generated in an acidic buffer than in a basic buffer. The rate-pH profile for mAb1 can be deconvoluted to Fc and Fab. The Fc deamidation showed a V-shaped profile: deamidation of PENNY peptide is responsible for the rate at high-pH, whereas deamidation of a new site, Asn323, may be responsible for the rate at low-pH. The profile for Fab is a straight line without curvature. PMID:23568760

Pace, Amanda L; Wong, Rita L; Zhang, Yonghua Taylor; Kao, Yung-Hsiang; Wang, Y John

2013-04-09

432

21 CFR 73.2396 - Lead acetate.  

Code of Federal Regulations, 2013 CFR

...ADDITIVES EXEMPT FROM CERTIFICATION Cosmetics § 73.2396 Lead acetate. (a...additive lead acetate may be safely used in cosmetics intended for coloring hair on the scalp...The amount of the lead acetate in the cosmetic shall be such that the lead...

2013-04-01

433

27 CFR 21.107 - Ethyl acetate.  

Code of Federal Regulations, 2013 CFR

...107 Ethyl acetate. (a) 85 percent ester: (1) Acidity (as acetic acid). Not more than 0.015 percent by weight...and none above 80 °C. (b) 100 percent ester: (1) Acidity (as acetic acid). Not more than 0.010 percent by...

2013-04-01

434

Kinetics of the Methanogenic Fermentation of Acetate  

PubMed Central

Inhibition of the fermentation of acetate to methane and carbon dioxide by acetate was analyzed with an acetate-acclimatized sludge and with Methanosarcina barkeri Fusaro under mesophilic conditions. A second-order substrate inhibition model, qch4 = qmS/[Ks + S + (S2/Ki)], where S was the concentration of undissociated acetic acid, not ionized acetic acid, could be applicable in both cases. The analysis resulted in substrate saturation constants, Ks, of 4.0 ?M for the acclimatized sludge and 104 ?M for M. barkeri. The threshold concentrations of undissociated acetic acid when no further acetate utilization was observed were 0.078 ?M (pH 7.50) for the acclimatized sludge and 4.43 ?M (pH 7.45) for M. barkeri. These kinetic results suggested that the concentration of undissociated acetic acid became a key factor governing the actual threshold acetate concentration for acetate utilization and that the acclimatized sludge in which Methanothrix spp. appeared dominant could utilize acetate better and survive at a lower concentration of undissociated acetic acid than could M. barkeri. Images

Fukuzaki, Satoshi; Nishio, Naomichi; Nagai, Shiro

1990-01-01

435

Determination of Battery Storage Capacity in Energy Buffer for Wind Farm  

Microsoft Academic Search

Design of a battery energy storage system (BESS) in a buffer scheme is examined for the purpose of attenuating the effects of unsteady input power from wind farms. The design problem is formulated as maximization of an objective function that measures the economic benefit obtainable from the dispatched power from the wind farm against the cost of the BESS. Solution

X. Y. Wang; D. Mahinda Vilathgamuwa; S. S. Choi

2008-01-01

436

Thermochemical Studies of Human Red Blood Cells: Enthalpy Changes on Dilution in Buffers  

Microsoft Academic Search

Enthalpy changes on dilution of human red blood cells with buffer solutions over the pH range 6 to 8 at 30 degrees C have been measured by microcalorimetry. From the results a value has been obtained for the enthalpy of ionization of the histidine residues in intracellular haemoglobin which is close to the enthalpy of ionization of the imidazole group

M. N. Jones; C. Zala

1974-01-01

437

Chemical equilibrations with soil buffer systems as bases for future soil testing programs  

Microsoft Academic Search

The soil has mechanisms which serve as buffers or ionic reservoirs which remove nutrient ions from and return them to the soil solution and thus regulate their availabilities to higher plants. Yet relative amounts of each type of cation?exchange bond are evidently so different from soil to soil that basic cation saturation ratios per se seem unimportant to the well?being

E. O. McLean

1982-01-01

438

Mineralogical sources of the buffer capacity in a granite catchment determined by strontium isotopes  

Microsoft Academic Search

The role of different minerals in base cation release and thus the increase of buffering capacity of groundwater against acid deposition is controversially discussed in the literature. The 87Sr\\/86Sr ratios and base cation concentration were investigated in whole rock leachates, mineral separates, precipitation, soil solution, groundwater and stream water samples in the Lehstenbach catchment (Germany) to identify the weathering sequence

Christina Weyer; Gunnar Lischeid; Luc Aquilina; Anne-Catherine Pierson-Wickmann; Charlotte Martin

2008-01-01

439

Post-harvest Riparian Buffer Response: Implications for Wood Recruitment Modeling and Buffer Design  

NASA Astrophysics Data System (ADS)

Despite the importance of riparian buffers in providing aquatic functions to forested streams, few studies have sought to capture key differences in ecological and geomorphic processes between buffered sites and forested conditions. This study examines post-harvest buffer conditions from 20 randomly selected harvest sites within a managed tree farm in the Cascade Mountains of western Washington. Post-harvest wind derived treefall rates in buffers up to three years post-harvest averaged 268 trees/km/year, 26 times greater than competition-induced mortality rate estimates. Treefall rates and stem breakage were strongly tied to tree species and relatively unaffected by stream direction. Observed treefall direction is strongly biased toward the channel, irrespective of channel or buffer orientation. Fall direction bias can deliver significantly more wood recruitment relative to randomly directed treefall, suggesting that models that utilize the random fall assumption will significantly underpredict recruitment. A simple estimate of post-harvest wood recruitment from buffers can be obtained from species specific treefall and breakage rates, combined with bias corrected recruitment probability as a function of source distance from the channel. Post-harvest wind effects may reduce the standing density of trees enough to significantly reduce or eliminate competition mortality and thus indirectly alter bank erosion rates, resulting in substantially different wood recruitment dynamics from buffers as compared to unmanaged forests.

Liquori, Michael K.

2006-02-01

440

Texturing influence of process parameters in sol–gel Tb 2O 3 buffer layers on Ni tapes for YBCO coated conductors  

Microsoft Academic Search

In this study, texturing influence of process parameters in sol–gel Tb2O3 buffer layers on textured Ni tapes was evaluated. A solution deposition process was used to grow epitaxial Tb2O3 buffer layers on the Ni tapes for YBa2Cu3O7?x (YBCO) coated conductors. The Tb2O3 precursor solution was prepared using solvent, chelating agents and modifying chemical liquid materials. The solution was dip-coated onto

Erdal Celik; Yusuf S Hascicek

2002-01-01

441

Simultaneous Gas Chromatography-Mass Spectrometry Quantification of Endogenous [12C]- and Applied [13C]Indole-3yl-Acetic Acid Levels in Growing Maize Roots  

PubMed Central

The use of stable indole-3yl-acetic acid (IAA) labeled by 6 atoms of 13C allowed, after [13C]IAA treatment, simultaneous gas chromatography-mass spectrometry quantifications of both endogenous [12C]IAA and applied [13C]IAA levels in Zea mays L. roots. Root material was immersed for 1 hour in a buffered (pH 6.0) solution without or with [13C]IAA at 10?7 molar. Both applied and endogenous IAA were thus measured for three zones of the roots (apical, elongating, differentiating) directly after treatment and also 2 hours later. Growth was followed over a 4 hour period. Roots not immersed elongated more than control roots (immersed in buffer), which grew more than IAA-treated roots. Immersion in buffer induced a large decrease (?68%) of [12C]IAA in the apical part of control roots, whereas immersion in [13C]IAA prevented most of it. No significant difference between control and treated roots occurred in the two other zones. Two hours after treatment, [13C]IAA had completely disappeared from the elongating zone even though [12C]IAA level was essentially stable. A direct relationship occurred between the level of IAA in the elongating zone and the growth of the root. This relationship was strongly disturbed if unmetabolized [13C]IAA was present. However, the relationship returned to its initial state when significant amounts of free [13C]IAA were no longer detectable. These results are discussed in terms of the stability of both types of compounds and the utility of the method of using stable isotopes of hormones, for the understanding of hormonal regulation of plant growth.

Meuwly, Philippe; Pilet, Paul-Emile

1991-01-01

442

Comparison of zwitterionic N-alkylaminomethanesulfonic acids to related compounds in the Good buffer series  

PubMed Central

Summary Several N-alkyl and N,N-dialkylaminomethanesulfonic acids were synthesized (as zwitterions and/or sodium salts) to be tested for utility as biological buffers at lower pH levels than existing Good buffer compounds (aminoalkanesulfonates with a minimum of two carbons between amine and sulfonic acid groups as originally described by Norman Good, and in common use as biological buffers). Our hypothesis was that a shorter carbon chain (one carbon) between the amino and sulfonic acid groups should lower the ammonium ion pK a values. The alkylaminomethanesulfonate compounds were synthesized in aqueous solution by reaction of primary or secondary amines with formaldehyde/sodium hydrogensulfite addition compound. The pK a values of the ammonium ions of this series of compounds (compared to existing Good buffers) was found to correlate well with the length of the carbon chain between the amino and sulfonate moeties, with a significant decrease in amine basicity in the aminomethanesulfonate compounds (pK a decrease of 2 units or more compared to existing Good buffers). An exception was found for the 2-hydroxypiperazine series which shows only a small pK a decrease, probably due to the site of protonation in this compound (as confirmed by X-ray crystal structure). X-ray crystallographic structures of two members of the series are reported. Several of these compounds have pK a values that would indicate potential utility for buffering at pH levels below the normal physiological range (pK a values in the range of 3 to 6 without aqueous solubility problems) – a range that is problematic for currently available Good buffers. Unfortunately, the alkylaminomethanesulfonates were found to degrade (with loss of their buffering ability) at pH levels below the pK a value and were unstable at elevated temperature (as when autoclaving) – thus limiting their utility.

Hilliard, Newton P; Chhatre, Suneel A; Timofeeva, Tatiana V; Yakovenko, Andrey A; Dei, Daniel K; Mensah, Enoch A

2010-01-01

443

Managing Buffer Stocks to Stabilize Wheat Prices.  

National Technical Information Service (NTIS)

A wheat buffer stock simulation model is used to add random deviations of wheat yields and exports to projected supply and demand conditions for 1976-82. The result is a useful analytical tool for policy analysis-especially for the analysis of questions a...

J. A. Sharples R. L. Walker R. W. Slaughter

1976-01-01

444

Buffer layers on biaxially textured metal substrates  

DOEpatents

A method is disclosed for forming a biaxially textured buffer layer on a biaxially oriented metal substrate by using a sol-gel coating technique followed by pyrolyzing/annealing in a reducing atmosphere. This method is advantageous for providing substrates for depositing electronically active materials thereon.

Shoup, Shara S. (Woodstock, GA); Paranthamam, Mariappan (Knoxville, TN); Beach, David B. (Knoxville, TN); Kroeger, Donald M. (Knoxville, TN); Goyal, Amit (Knoxville, TN)

2001-01-01

445

Specifying memory consistency of write buffer multiprocessors  

Microsoft Academic Search

Write buffering is one of many successful mechanisms that improves the performance and scalability of multiprocessors. However, it leads to more complex memory system behavior, which cannot be described using intuitive consistency models, such as Sequential Consistency. It is crucial to provide programmers with a specification of the exact behavior of such complex memories. This article presents a uniform framework

Lisa Higham; Lillanne Jackson; Jalal Kawash

2007-01-01

446

Lexical influences in graphemic buffer disorder  

Microsoft Academic Search

We report the case of patient BH, who misspelled about half of the words she attempted and showed the characteristic features of “graphemic buffer disorder” (an effect of letter length on spelling accuracy, errors involving the substitution, omission, addition, and movement of letters that affect the middles more than the ends of words). Speech comprehension and production were good. Reading

Karen Sage; Andrew W. Ellis

2004-01-01

447

The Graphemic Buffer and attentional mechanisms*1  

Microsoft Academic Search

Two patients with acquired dysgraphia were reported. The patients' performance in various written and oral spelling tasks converge in support of the hypothesis that they have selective damage, within the spelling system, to the Graphemic Buffer. Although the patients present with comparable patterns of error types, they differ in the distribution of errors as a function of letter position in

ARGYE E. HILLIS; ALFONSO CARAMAZZA

1989-01-01

448

How tendons buffer energy dissipation by muscle.  

PubMed

To decelerate the body and limbs, muscles lengthen actively to dissipate energy. During rapid energy-dissipating events, tendons buffer the work done on muscle by storing elastic energy temporarily, then releasing this energy to do work on the muscle. This elastic mechanism may reduce the risk of muscle damage by reducing peak forces and lengthening rates of active muscle. PMID:23873133

Roberts, Thomas J; Konow, Nicolai

2013-10-01

449

Buffer Size Requirements Under Longest Queue First  

Microsoft Academic Search

A model of a switching component in a packet switching network is considered. Packetsfrom several incoming channels arrive and must be routed to the appropriate outgoingport according to a service policy. A task confronting the designer of such a system is theselection of policy and the determination of the corresponding input buffer requirementswhich will prevent packet loss. One natural choice

H. Richard Gail; George A. Grover; Roch Guérin; Sidney L. Hantler; Zvi Rosberg; Moshe Sidi

1993-01-01

450

Stress, Social Support, and the Buffering Hypothesis  

Microsoft Academic Search

The purpose of this article is to determine whether the positive association between social support and well-being is attributable more to an overall beneficial effect of support (main- or direct-effect model) or to a process of support protecting persons from potentially adverse effects of stressful events (buffering model). The review of studies is organized according to (a) whether a measure

Sheldon Cohen; Thomas Ashby Wills

1985-01-01

451

Control of electrochemical reactions at the capillary electrophoresis outlet/electrospray emitter electrode under CE/ESI-MS through the application of redox buffers.  

PubMed

It was found that combining capillary electrophoresis (CE) and electrospray ionization mass spectrometry (ESI-MS) overlays two controlled current techniques to form a three-electrode system (CE inlet, CE outlet/ES emitter, and MS inlet electrodes) in which the CE outlet electrode and the ES emitter electrode were shared between the CE and the ESI-MS circuits. Depending on the polarities and magnitudes of the voltages at the CE inlet, CE outlet/ES emitter, and MS inlet electrodes, the nature of the two redox reactions at the shared electrode was the same or different (both reduction, both oxidation, or one oxidation and the other reduction). Several redox buffers were introduced for controlling electrochemical reactions at the shared electrode. By reacting at this electrode, redox buffers were able to maintain electrode potentials below the onset of water electrolysis, thereby eliminating gas bubble formation and/or pH drift. The volume of the gas generated due to water electrolysis was used to quantitate water oxidation or reduction at this electrode. Two types of redox buffers were used. A reactive electrode with an oxidation potential below that of water was used as the electrode under anodic conditions. Also, a reactive compound with a redox potential below that of water was added to the CE and/or ESI running buffer. When the shared electrode was the anode of both CE and ESI-MS circuits, the use of iron or etched and sanded stainless steel (ss) wire, instead of platinum wire, suppressed bubble formation at the shared electrode. Under these conditions, corrosion of the Fe wire and formation of Fe2+ replaced oxidation of water, eliminating O2 gas bubble and H+ formation. When mixtures of peptides were analyzed, iron adducts of peptides were observed. For a fresh wire, however, the intensities of adduct ions were less than 3% of the protonated molecules. After a few days of operation, the intensities of the adduct ions increased to approximately 50%, due to rust formation on the Fe wire. On-column rinsing with a 40% solution of citric acid rejuvenated the Fe wire and reduced the adduct peak intensities to less than 3%. Unmodified ss wire did not quench bubble formation, which was attributed to its passivated surface. When Fe, ss, and Pt wires were used as the shared electrode under forward polarity CE and positive ESI mode, where the shared electrode acted as a cathode with respect to CE inlet and as an anode with respect to MS inlet, reduction of water at the cathodic end of the electrode and, in the case of ss and Pt wires, oxidation of water at the anodic end of the shared electrode produced a significant amount of bubbles. Under these conditions, however, a buffer containing 50 mM p-benzoquinone completely suppressed both cathodic reduction and anodic oxidation of water for CE currents up to 4 microA. Reduction of p-benzoquinone at the cathodic end of the shared electrode to hydroquinone, and oxidation of this hydroquinone at the anodic end of the electrode, replaced reduction and oxidation of water, eliminating bubble formation. A 0.1% acetic acid solution saturated with I2 was also found to suppress bubble formation at the cathode for CE currents up to 3 microA; however, strong iodine adduct ions were observed under CE/ESI-MS when a mixture of peptides was analyzed. The application of iron as an in-capillary electrode for the analysis of a peptide mixture and a protein digest demonstrated a high separation efficiency similar to when hydroquinone was used as a redox buffer. PMID:11199972

Smith, A D; Moini, M

2001-01-15

452

Modified alginate composite membranes for the dehydration of acetic acid  

Microsoft Academic Search

Alginate composite membranes cross-linked with 1,6-hexanediamine (HDM) or poly(vinyl alcohol) (PVA) were prepared by casting an aqueous solution of alginate and HDM or PVA on a hydrolyzed microporous polyacrylonitrile (PAN) membrane and characterized by pervaporation separation of acetic acid\\/water mixtures. The influence of hydrolysis of PAN support layer and HDM content in dense layer on separation performance of the composite

Xin-Ping Wang

2000-01-01

453

Strong ion reserve: a viewpoint on acid base equilibria and buffering.  

PubMed

Evidence suggests that strong ions can exist reversibly bound to proteins in a pH-dependent manner and that they can be recruited into the biological solution, modulating its strong ion difference in a process that opposes the acid base disturbances imposed on the system. These recruitable strong ions represent the solution's 'strong ion reserve'. The physiologic [corrected] role of these protein-bound strong ions [corrected] in the buffering of acid base disorders is discussed. PMID:21210280

Agrafiotis, Michalis

2011-01-06

454

Stability of exenatide in poly(d,l-lactide-co-glycolide) solutions: A simplified investigation on the peptide degradation by the polymer.  

PubMed

A solution model can be used to elucidate drug stability issues in a complex system. The aim of this study was to investigate the interaction between poly(d,l-lactide-co-glycolide) (PLGA) and exenatide in organic solvent-acetate buffer saline (ABS) solutions. The effect of solvent composition on exenatide stability was investigated first. In the selected 90:10 dimethyl sulfoxide (DMSO):ABS solution, exenatide stability was examined as a function of PLGA comonomer ratios, molecular weight (Mw) and concentrations. The specific rotation analysis and second derivative UV absorbance spectroscopy were used to monitor the variation of exenatide higher order structure. The effect of ABS pH on the interaction was also investigated. Exenatide degradation products were characterized by HPLC-MS/MS. It was found that exenatide was relatively stable in glacial acetic acid (HAc)-ABS solutions, whereas DMSO content had a strong influence on the conformation state and stability of exenatide. PLGA 50:50 promoted exenatide degradation more than PLGA 75:25 and poly(d,l-lactide) (PLA). Lower Mw and higher concentration of PLGA were beneficial for exenatide degradation. Exenatide was more stable in 90:10 DMSO:ABS (pH 3.0) solution than in 90:10 DMSO:ABS (pH 4.5 and 3.0) solutions during the incubation. HPLC-MS/MS analysis of exenatide demonstrated that acylation was the main degradation route of the peptide. PMID:23994054

Liang, Rongcai; Zhang, Renyu; Li, Xiang; Wang, Aiping; Chen, Daquan; Sun, Kaoxiang; Liu, Wanhui; Li, Youxin

2013-08-29

455

Biocompatibility and buffers: Effect of bicarbonate-buffered peritoneal dialysis fluids on peritoneal cell function  

Microsoft Academic Search

Biocompatibility and buffers: Effect of bicarbonate-buffered peritoneal dialysis fluids on peritoneal cell function.BackgroundConventional peritoneal dialysis fluids (PDF) have been shown to compromise the function of both leukocytes and human peritoneal mesothelial cells (HPMC). Various in vitro studies have identified the low initial pH in combination with high lactate content, as well as the hyperosmolality and high glucose concentration present in

Achim Jörres; Thorsten O Bender; André Finn; Janusz Witowski; Sibylle Fröhlich; Gerhard M Gahl; Ulrich Frei; Heiko Keck; Jutta Passlick-Deetjen

1998-01-01

456

Fabrication of SmBiO3/NiO Double Buffer Layer for Coated Conductors  

NASA Astrophysics Data System (ADS)

NiO layers were prepared in Ar flow at temperatures between 750°C to 850°C by using surface oxidation epitaxial method on Ni-5%W alloy substrates. NiO(200) buffer layer with well textured, smooth, dense and crack-free surface was prepared in Ar ambience with a flow rate of 500 ml/min at 800°C for 10.0 min. Then SmBiO3 buffer layer was coated on the well epitaxial NiO(200) layer by chemical solution deposition (CSD) method.

Lei, Ming; Yang, Xinsheng; Zhao, Yong

2013-06-01

457

Separation of double-stranded DNA in conventional and isoelectric buffers: studies on stability and separation performance  

Microsoft Academic Search

In the capillary electrophoresis of double-stranded DNA in isoelectric buffers, worsening of resolution was observed in electropherograms as a function of time passed from the preparation of the separation solution, which consisted of 0.7% hydroxypropylcellulose, HPC, Mr 106, diluted in 150 mM histidine buffer. The DNA standards used were: kilobase pair-ladder, Marker V and Marker VI. In order to understand

Soffia Magnusdottir; Cecilia Gelfi; Mahmoud Hamdan; Pier Giorgio Righetti

1999-01-01

458

Chemically deposited La2Zr2O7 buffer layers for YBCO-coated conductors: film growth and microstructure  

Microsoft Academic Search

An adequate buffer layer architecture is of great importance for YBa2Cu3O7-delta (YBCO)-coated conductor fabrication. We present a transmission electron microscopy (TEM) analysis of La2Zr2O7 (LZO) buffer layers on biaxially textured Ni-5 at.%W substrates for YBCO-coated conductors prepared by chemical solution deposition (CSD). The LZO thin films were heat-treated at 900 and 1050 °C respectively. Electron diffraction patterns, and bright and

L. Molina; K. Knoth; S. Engel; B. Holzapfel; O. Eibl

2006-01-01

459

Bound and determined: a computer program for making buffers of defined ion concentrations.  

PubMed

A computer program that allows the preparation of buffers containing known concentrations of metal-ligand complexes at defined pH values and temperatures is described. Ligands are defined as compounds that bind metals and may include AMP, ADP, ATP, GMP, GDP, GTP, EGTA, EDTA, BAPTA, phosphate, sulfate, chloride, monocarboxylic acids, dicarboxylic acids, organophosphates, and/or citric acid. Metals may include sodium, potassium, magnesium, calcium, and/or manganese. The program uses association constants corrected for temperature and ionic strength so that solutions between 0 and 40 degrees C and between pH values of 4 and 10 can be defined. The program can perform the following: (i) calculate the concentration of all metal-ligand complexes when total metal and total ligand concentrations are known, (ii) calculate the concentration of metal ion required to make a solution of known free metal ion concentration when total ligand concentrations are known, (iii) calculate the concentration of ligand required to make a solution of known free metal ion concentration when total metal concentrations are known, and (iv) calculate the total concentrations of metal and ligand required to make a buffer of known metal-ligand concentration. Options i-iii are useful for making buffers of defined free metal ion concentrations; option iv is useful for making buffers of defined metal-nucleotide concentrations. PMID:1621949

Brooks, S P; Storey, K B

1992-02-14

460

Selective recognition of acetate ion based on fluorescence enhancement chemosensor.  

PubMed

Fluorescence study of the complexation between uranyl salophen (L) and some common anions in acetonitrile-water (90:10, v/v) solution showed a tendency of L toward acetate ion (AcO-). The fluorescence enhancement of L is attributed to a 1:1 complex formation between L and acetate ion which was utilized as the basis for the selective detection of AcO-. The association constant of the 1:1 complex formation of L-AcO- was calculated as 6.60?×?10(6) . The linear response range of the fluorescent chemosensor covers a AcO- concentration range of 1.6?×?10(-7) to 2.5?×?10(-5) ?mol/L, with a detection limit of 2.5?×?10(-8) ?mol/L. L showed a selective and sensitive fluorescence enhancement response toward acetate ion over I3- , NO3-, CN-, CO3 (2-), Br-, Cl-, F-, H2 PO4- and SO4 (2-) , which was attributed to the higher stability of inorganic complex between acetate and L. PMID:22371380

Hosseini, Morteza; Ganjali, Mohammad Reza; Veismohammadi, Bahareh; Faridbod, Farnoush; Abkenar, Shiva Dehghan; Salavati-Niasari, Masoud

2012-02-28

461

The influence of host–guest inclusion complex formation on the biotransformation of cortisone acetate ? 1-dehydrogenation  

Microsoft Academic Search

An intensive and systematic investigation had been carried out on the ?1-dehydrogenation of cortisone acetate (CA) to prednisone acetate (PA) by Arthrobacter simplex TCCC 11037 in the presence of native and modified ?-cyclodextrins (?-CDs). The biotransformation was improved through the formation of the host–guest inclusion complex between CA and CDs in aqueous solution. The inclusion complexes of CDs with CA

Yin-Hu Ma; Min Wang; Zhi Fan; Yan-Bing Shen; Li-Ting Zhang

2009-01-01

462

Simple buffers for 3D STORM microscopy  

PubMed Central

3D STORM is one of the leading methods for super-resolution imaging, with resolution down to 10 nm in the lateral direction, and 30–50 nm in the axial direction. However, there is one important requirement to perform this type of imaging: making dye molecules blink. This usually relies on the utilization of complex buffers, containing different chemicals and sensitive enzymatic systems, limiting the reproducibility of the method. We report here that the commercial mounting medium Vectashield can be used for STORM of Alexa-647, and yields images comparable or superior to those obtained with more complex buffers, especially for 3D imaging. We expect that this advance will promote the versatile utilization of 3D STORM by removing one of its entry barriers, as well as provide a more reproducible way to compare optical setups and data processing algorithms.

Olivier, Nicolas; Keller, Debora; Rajan, Vinoth Sundar; Gonczy, Pierre; Manley, Suliana

2013-01-01

463

Simple buffers for 3D STORM microscopy.  

PubMed

3D STORM is one of the leading methods for super-resolution imaging, with resolution down to 10 nm in the lateral direction, and 30-50 nm in the axial direction. However, there is one important requirement to perform this type of imaging: making dye molecules blink. This usually relies on the utilization of complex buffers, containing different chemicals and sensitive enzymatic systems, limiting the reproducibility of the method. We report here that the commercial mounting medium Vectashield can be used for STORM of Alexa-647, and yields images comparable or superior to those obtained with more complex buffers, especially for 3D imaging. We expect that this advance will promote the versatile utilization of 3D STORM by removing one of its entry barriers, as well as provide a more reproduci