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1

Alkaline Hydrolysis of CL-20.  

National Technical Information Service (NTIS)

The Energetics and Warheads Division of the U.S. Army Armament Research, Development and Engineering Center has been involved in the development of CL-20. An alkaline hydrolysis study was performed to better understand the fate and transport of CL-2O thro...

P. Karakaya M. Sidhourn C. Christodoulatos W. Balas S. Nicolich

2005-01-01

2

Alkaline Hydrolysis Conversion of Nitrocellulose Fines.  

National Technical Information Service (NTIS)

The conversion of 1,125,000 pounds of bone-dry nitrocellulose fines into a liquid fertilizer was documented. Alkaline hydrolysis was the conversion method using potassium hydroxide to dissolve the nitrocellulose, phosphoric acid to adjust the pH and then ...

F. E. Wolf

1997-01-01

3

Kinetics of the alkaline hydrolysis of nitrocellulose.  

PubMed

Cellulose nitrate (nitrocellulose) is an explosive solid substance used in large quantities in various formulations of rocket and gun propellants. Safe destruction of nitrocellulose can be achieved by alkaline hydrolysis, which converts it to biodegradable products that can then be treated by conventional biological processes. The kinetics of the alkaline hydrolysis of munitions-grade nitrocellulose in sodium hydroxide solutions were investigated in completely mixed batch reactors. Experiments were conducted using solutions of alkaline strength ranging from 0.1 to 15% by mass and temperatures in the range of 30 to 90 degrees C. Regression analysis of the kinetic data revealed that alkaline hydrolysis of nitrocellulose is of the order 1.0 and 1.5 with respect to nitrocellulose and hydroxide concentration, respectively. The activation energy of the hydrolysis reaction was found to be 100.9 kJ/mol with a preexponential Arrhenius constant of 4.73 x 10(13). Nitrite and nitrate, in a 3:1 ratio, were the primary nitrogen species present in the posthydrolysis solution. The kinetic information is pertinent to the development and optimization of nitrocellulose chemical-biological treatment systems. PMID:11563378

Christodoulatos, C; Su, T L; Koutsospyros, A

4

Stability Patterns of Methoxy Phenols under Alkaline Hydrolysis Conditions  

Microsoft Academic Search

catechol plus their methyl and ethyl analogs, and phenol. The yield of ether-solubles was reported to reach a maximum of about 30% on a weight basis. The yield of identifiable phenolics was about 10% with catechol the largest product (~5%). Thring and co-workers studied the alkaline hydrolysis of lignins isolated with organic solvents, ethylene glycol (7) and ethanol (8). At

D. K. Johnson; J. Salvadób; E. Chornet

5

[Promoting high-temperature hydrolysis under alkaline condition].  

PubMed

The effect of alkaline thermal hydrolysis method on excess sludge and its characteristic parameters(such as soluble chemical oxygen demand, volatile fatty acids, ammonia-nitrogen, pH value, sludge concentration, etc.) were investigated. The results show that the addition of alkali can reduce the resistance of the sludge cells to high temperature and enhance the release and the hydrolysis of organic materials from the sludge cells with the increase of temperature, pH value and reaction time. The concentration of SCOD reached 17,950 mg/L and SCOD/TCOD was 0.65 on the conditions of pH 13, 170 degrees C and 75 min. The maximal dissolving rate of suspended solids (SS) was 67% and 72% for volatile suspended solids (VSS) at pH 13 with 60 min. The concentration of SCOD after alkaline thermal hydrolysis treatment increased with the increase of sludge concentration, in which the nice linear relation was reached and the correlation coefficient (R2) was above 0.97. The increasing rate of the SCOD was improving with the increase of the pH value and the SCOD of unit sludge reached 672 mg/g at pH 13. The effect of three factors on the SCOD was investigated through orthogonal experiment at the temperature of 170 degrees C, the importance was sludge concentration,pH value and reaction time in turn. PMID:18839582

He, Yu-feng; Yang, Feng-lin; Hu, Shao-wei; Sun, Cui; Liu, Zhong-qiang; Gong, Zheng

2008-08-01

6

Peroxyacetyl nitrate: comparison of alkaline hydrolysis and chemiluminescence methods  

SciTech Connect

Peroxyacetyl nitrate (PAN; CH/sub 3/C(O)OONO/sub 2/) was prepared from sunlight irradiation of organic-NO/sub x/ and chlorine-organic-NO/sub x/ mixtures in air, and its concentration was measured by using two methods. The first method involved ion chromatography following alkaline hydrolysis of PAN to acetate, and the second method involved PAN measurements using a chemiluminescent NO/sub x/ analyzer. The two methods were found to be in good agreement in the range of PAN concentrations tested, 0-400 ppb. Applications and limitations of the two methods are discussed for both laboratory and ambient measurements of PAN.

Grosjean, D.; Harrison, J.

1985-01-01

7

High-risk biodegradable waste processing by alkaline hydrolysis.  

PubMed

Biodegradable waste is by definition degraded by other living organisms. Every day, meat industry produces large amounts of a specific type of biodegradable waste called slaughterhouse waste. Traditionally in Europe, this waste is recycled in rendering plants which produce meat and bone meal and fat. However, feeding animals with meat and bone meal has been banned since the outbreaks of bovine spongiform encephalopathy (BSE). In consequence, new slaughterhouse waste processing technologies have been developed, and animal wastes have now been used for energy production. Certain parts of this waste, such as brains and spinal cord, are deemed high-risk substances, because they may be infected with prions. Their treatment is therefore possible only in strictly controlled conditions. One of the methods which seems to bear acceptable health risk is alkaline hydrolysis. This paper presents the results of an alkaline hydrolysis efficiency study. It also proposes reuse of the obtained material as organic fertiliser, as is suggested by the analytical comparison between meat and bone meal and hydrolysate. PMID:21971109

Kalambura, Sanja; Vo?a, Neven; Kri?ka, Tajana; Sindrak, Zoran; Spehar, Ana; Kalambura, Dejan

2011-09-01

8

Management of spent solvents by alkaline hydrolysis process  

SciTech Connect

This paper deals with the treatment method for the management of spent solvents of reprocessing origin (30% tri-n-butyl phosphate in n-dodecane) using the alkaline hydrolysis process. The consolidated work reported herein has established total conversion of TBP to aqueous soluble reaction products and transfer of near total radioactivity associated with the waste into this aqueous phase. It was also observed that n-dodecane did not take part in the reaction and separated out as the top layer. Repeated runs have established the process on engineering scale with regard to conversion of TBP into sodium salt of HDBP, butanol and recovery of the diluent practically free of TMP. The measured parameters, specifically, temperature and pressure did not deviate from set limits during the entire reaction time indicating safe operation. Experiments were also carried out on immobilization of the aqueous phase resulting from hydrolysis which contains almost all the radioactivity associated with the original spent solvent. These immobilization studies have established compatibility of the process generated aqueous stream with cementitious matrix.

Manohar, S.; Srinivas, C.; Vincent, T.; Wattal, P.K.

1999-07-01

9

The Origins of Phenol Produced in the Rapid Hydrothermolysis and Alkaline Hydrolysis of Hybrid Poplar Lignins  

Microsoft Academic Search

Hybrid poplar lignins were isolated from selected hybrid poplar clones by an enzymatic\\/solvent extraction method. The lignins were subjected to both rapid hydrothermolysis (RHT) and alkaline hydrolysis. Phenol (C6H6OH) was the predominant component of hydrothermolysis products, whilst p-hydroxybenzoic acid (PHBA) was the chief product of the alkaline hydrolysis. Phenol yields were 2–9 wt.% of the lignin, whilst PHBA yields ranged

F. A. Agblevor; D. G. B. Boocock

1989-01-01

10

Safe operating temperatures for pressurized alkaline hydrolysis of HMX-based explosives  

Microsoft Academic Search

Alkaline hydrolysis is used to convert high explosives to nonenergetic, aqueous compounds. Base hydrolysis of high explosives is exothermic (H{sub RXN} = 2.3 kJ\\/g), and thermal runaway of the reaction is a possibility at elevated temperatures (>120 C) where the rate of reaction is large. Thermal runaway could result in an accidental detonation of the energetic material being treated, so

Robert L. Bishop; David M. Harradine; Raymond L. Flesner; Sheldon A. Larson; David A. Bell

2000-01-01

11

Detection of bound phenolic acids: prevention by ascorbic acid and ethylenediaminetetraacetic acid of degradation of phenolic acids during alkaline hydrolysis  

Microsoft Academic Search

The experimental conditions commonly used to detect bound phenolic acids by alkaline hydrolysis result in loss of several phenolic acids, particularly dihydroxy-derivatives (caffeic acid, dihydrocaffeic acid, homogentisic acid). In this study we show that the addition of ascorbic acid, a strong antioxidant, and ethylenediaminetetraacetic acid, a metal chelator, totally prevent the loss of phenolic acids during alkaline hydrolysis. In these

M Nardini; E Cirillo; F Natella; D Mencarelli; A Comisso; C Scaccini

2002-01-01

12

Aqueous solubility and alkaline hydrolysis of the novel high explosive hexanitrohexaazaisowurtzitane (CL-20).  

PubMed

The recently developed polycyclic nitramine CL-20 is considered as a possible replacement for the monocyclic nitramines RDX and HMX. The present study reports aqueous solubility data for CL-20, as well as the kinetic parameters for its alkaline hydrolysis with sodium hydroxide below and above its solubility limits. Aqueous solubility of CL-20 was measured in the temperature range of 4-69 degrees C and the data were fitted to a generalized solubility model. Alkaline hydrolysis experiments were conducted at 15, 20, 30 and 40 degrees C, with hydroxide concentrations ranging from 0.25 to 300 mM. Like RDX and HMX, alkaline hydrolysis of CL-20 follows second-order kinetics. CL-20 alkaline hydrolysis was found to proceed at a significantly faster rate than RDX. The temperature dependency of the second-order rate constants was evaluated using the Arrhenius model. The activation energy for CL-20 was found to be within close range of the activation energies reported for RDX and HMX. PMID:15811680

Karakaya, Pelin; Sidhoum, Mohammed; Christodoulatos, Christos; Nicolich, Steve; Balas, Wendy

2005-04-11

13

AN ALKALINE HYDROLYSIS TISSUE DIGESTION SYSTEM FOR A BSL-3-AG CONTAINMENT FACILITY  

Technology Transfer Automated Retrieval System (TEKTRAN)

An alkaline hydrolysis tissue digestion system was installed at the Arthropod-borne Animal Diseases Research Laboratory (ABADRL) Biosafety Level (BSL) 3-AG containment facility in 2000 to replace the antiquated pathologic waste incinerator because of significant costs for upgrading this incinerator ...

14

Total fractionation of green tea residue by microwave-assisted alkaline pretreatment and enzymatic hydrolysis.  

PubMed

Total refinery of constituents of green tea residue was achieved by combination of microwave-assisted alkaline pretreatment and enzymatic hydrolysis. Alkaline pretreatment was effective at separating pectic polysaccharides, protein, phenolic compounds and aliphatic compounds (probably originating from cuticular components), and the solubilization rate was attained 64–74% by heating at 120–200 °C. The higher heating value (HHV) of alkali-soluble fraction attained 20.1 MJ/kg, indicating its usability as black-liquor-like biofuel. Successive cellulolytic enzymatic hydrolysis mainly converted cellulose into glucose and attained the maximum solubilization rate of 89%. Final residue was predominantly composed of aliphatic cuticular components with high proportion in 9,10,18-trihydroxyoctadecanoic acid (30.1–48.6%). These cuticular components are potential alternative feedstock for aliphatic compounds commonly found in oil plants. PMID:23384782

Tsubaki, Shuntaro; Azuma, Jun-ichi

2013-01-11

15

Aqueous solubility and alkaline hydrolysis of the novel high explosive hexanitrohexaazaisowurtzitane (CL20)  

Microsoft Academic Search

The recently developed polycyclic nitramine CL-20 is considered as a possible replacement for the monocyclic nitramines RDX and HMX. The present study reports aqueous solubility data for CL-20, as well as the kinetic parameters for its alkaline hydrolysis with sodium hydroxide below and above its solubility limits. Aqueous solubility of CL-20 was measured in the temperature range of 4–69°C and

Pelin Karakaya; Mohammed Sidhoum; Christos Christodoulatos; Steve Nicolich; Wendy Balas

2005-01-01

16

Enhanced enzymatic hydrolysis of spruce by alkaline pretreatment at low temperature  

Microsoft Academic Search

Alkaline pretreatment of spruce at low tem­ perature in both presence and absence of urea was studied. It was found that the enzymatic hydrolysis rate and efficiency can be significantly improved by the pretreatment. At low temperature, the pretreatment chemicals, either NaOH alone or NaOH-urea mixture solution, can slightly remove lignin, hemicelluloses, and cellulose in the lignocellulosic materials, disrupt the

Yulin Zhao; Ying Wang; J. Y. Zhu; Art Ragauskas; Yulin Deng

2008-01-01

17

Kinetic study of alkaline protease 894 for the hydrolysis of the pearl oyster Pinctada martensii  

NASA Astrophysics Data System (ADS)

A new enzyme (alkaline protease 894) obtained from the marine extremophile Flavobacterium yellowsea (YS-80-122) has exhibited strong substrate-binding and catalytic activity, even at low temperature, but the characteristics of the hydrolysis with this enzyme are still unclear. The pearl oyster Pinctada martensii was used in this study as the raw material to illustrate the kinetic properties of protease 894. After investigating the intrinsic relationship between the degree of hydrolysis and several factors, including initial reaction pH, temperature, substrate concentration, enzyme concentration, and hydrolysis time, the kinetics model was established. This study showed that the optimal conditions for the enzymatic hydrolysis were an initial reaction pH of 5.0, temperature of 30°C, substrate concentration of 10% (w/v), enzyme concentration of 2 500 U/g, and hydrolysis time of 160 min. The kinetic characteristics of the protease for the hydrolysis of P. martensii were obtained. The inactivation constant was found to be 15.16/min, and the average relative error between the derived kinetics model and the actual measurement was only 3.04%, which indicated a high degree of fitness. Therefore, this study provides a basis for the investigation of the concrete kinetic characteristics of the new protease, which has potential applications in the food industry.

Chen, Xin; Chen, Hua; Cai, Bingna; Liu, Qingqin; Sun, Huili

2013-05-01

18

Alkaline hydrolysis of dimethyl terephthalate in the presence of [LiAl2(OH)6]Cl·2H2O  

NASA Astrophysics Data System (ADS)

The alkaline hydrolysis of dimethyl terephthalate (DMT) in the presence of [LiAl2(OH)6]Cl has been investigated to demonstrate a possible application of anion exchange facility of layered double hydroxides (LDHs) to control chemical reactions. The results show that (i) in the alkaline hydrolysis of DMT in the presence of [LiAl2(OH)6]Cl, most of the interlayer Cl- of [LiAl2(OH)6]Cl is quickly replaced by OH- in the alkaline solution because the LDH host favors OH- more; (ii) the alkaline hydrolysis of DMT in the presence of [LiAl2(OH)6]Cl is faster than the reaction of DMT and [LiAl2(OH)6]OH; (iii) The hydrolysis of DMT in a buffer solution of pH?8 takes longer time to reach equilibrium than the alkaline hydrolysis of DMT in the presence of [LiAl2(OH)6]Cl. It is believed that the selective anion exchange chemistry of the LDH plays a key role in storage and controlled release of active reactant, that is, OH-, thus make the hydrolysis proceeds in a controlled way.

Lei, Lixu; Zhang, Weifeng; Hu, Meng; Zheng, Hegen

2006-11-01

19

Enhanced enzymatic hydrolysis of spruce by alkaline pretreatment at low temperature.  

PubMed

Alkaline pretreatment of spruce at low temperature in both presence and absence of urea was studied. It was found that the enzymatic hydrolysis rate and efficiency can be significantly improved by the pretreatment. At low temperature, the pretreatment chemicals, either NaOH alone or NaOH-urea mixture solution, can slightly remove lignin, hemicelluloses, and cellulose in the lignocellulosic materials, disrupt the connections between hemicelluloses, cellulose, and lignin, and alter the structure of treated biomass to make cellulose more accessible to hydrolysis enzymes. Moreover, the wood fiber bundles could be broken down to small and loose lignocellulosic particles by the chemical treatment. Therefore, the enzymatic hydrolysis efficiency of untreated mechanical fibers can also be remarkably enhanced by NaOH or NaOH/urea solution treatment. The results indicated that, for spruce, up to 70% glucose yield could be obtained for the cold temperature pretreatment (-15 degrees C) using 7% NaOH/12% urea solution, but only 20% and 24% glucose yields were obtained at temperatures of 23 degrees C and 60 degrees C, respectively, when other conditions remained the same. The best condition for the chemical pretreatment regarding this study was 3% NaOH/12% urea, and -15 degrees C. Over 60% glucose conversion was achieved upon this condition. PMID:18023037

Zhao, Yulin; Wang, Ying; Zhu, J Y; Ragauskas, Art; Deng, Yulin

2008-04-15

20

Processing poultry feathers into keratin hydrolysate through alkaline-enzymatic hydrolysis.  

PubMed

Poultry feathers make up for as much as 8.5% of chicken weight and represent a considerable amount of almost pure keratin waste which is not being adequately utilized at the present time. The present study dealt with the processing of poultry feathers through a two-stage alkaline-enzymatic hydrolysis. In the first stage, feathers were mixed with a 0.1 or 0.3% KOH water solution in a 1 : 50 ratio and were incubated at 70°C for 24 h. After adjusting pH to 9, the effects examined in the second processing stage on the amount of degraded feathers were those of proteolytic enzyme additions (1-5%), time (4-8 h) and temperature (50-70°C). Processing feathers in 0.3% KOH and hydrolysing for 8 h in the second stage at 70°C with a 5% dose of enzyme (relative to dry feathers weight) produced approx. 91% degradation. Keratin hydrolysate is distinct for its high nitrogen content and reasonable inorganic solids level. Two-stage technology of alkaline-enzymatic hydrolysing of poultry feathers in an environment of 0.3% KOH achieves high efficiency under quite mild reaction conditions (temperature not exceeding 70°C with pH in a mildly alkaline region), and is feasible from an economic viewpoint. Keratin hydrolysate can find particular application in packaging technology (films, foils and encapsulates). PMID:20483878

Mokrejs, Pavel; Svoboda, Petr; Hrncirik, Josef; Janacova, Dagmar; Vasek, Vladimir

2010-05-18

21

Quantum chemical study of conformational preferences of intermediates and transition states in the alkaline hydrolysis of dimethyl phosphate  

NASA Astrophysics Data System (ADS)

The phosphate diester is a basic structure in DNA and RNA. The mechanism of phosphate diester hydrolysis is important for understanding the decomposition reactions of nucleic acids. In this study, we have explored the reaction pathway of alkaline hydrolysis of dimethyl phosphate, which is the simplest phosphate diester, with a hydroxide ion. Since the conformations of the intermediates and transition states reportedly influence the reaction mechanism of transacylation of methyl acetate with methoxide, we considered the conformational preferences on the alkaline hydrolysis of dimethyl phosphate, by using the most stable conformer as a reactant. Upon the reaction with hydroxide, a concerted reaction pathway was obtained in the gas phase, whereas a stepwise reaction pathway was obtained in water. As compared to the earlier study, our computation shows more stable conformations in the hydrolysis reactions than the previous study.

Takano, Y.; Kita, M.; Nakamura, H.

2013-08-01

22

Scale-up and integration of alkaline hydrogen peroxide pretreatment, enzymatic hydrolysis, and ethanolic fermentation.  

PubMed

Alkaline hydrogen peroxide (AHP) has several attractive features as a pretreatment in the lignocellulosic biomass-to-ethanol pipeline. Here, the feasibility of scaling-up the AHP process and integrating it with enzymatic hydrolysis and fermentation was studied. Corn stover (1?kg) was subjected to AHP pretreatment, hydrolyzed enzymatically, and the resulting sugars fermented to ethanol. The AHP pretreatment was performed at 0.125?g H(2) O(2) /g biomass, 22°C, and atmospheric pressure for 48?h with periodic pH readjustment. The enzymatic hydrolysis was performed in the same reactor following pH neutralization of the biomass slurry and without washing. After 48?h, glucose and xylose yields were 75% and 71% of the theoretical maximum. Sterility was maintained during pretreatment and enzymatic hydrolysis without the use of antibiotics. During fermentation using a glucose- and xylose-utilizing strain of Saccharomyces cerevisiae, all of the Glc and 67% of the Xyl were consumed in 120?h. The final ethanol titer was 13.7?g/L. Treatment of the enzymatic hydrolysate with activated carbon prior to fermentation had little effect on Glc fermentation but markedly improved utilization of Xyl, presumably due to the removal of soluble aromatic inhibitors. The results indicate that AHP is readily scalable and can be integrated with enzyme hydrolysis and fermentation. Compared to other leading pretreatments for lignocellulosic biomass, AHP has potential advantages with regard to capital costs, process simplicity, feedstock handling, and compatibility with enzymatic deconstruction and fermentation. Biotechnol. Bioeng. 2012; 109:922-931. © 2011 Wiley Periodicals, Inc. PMID:22125119

Banerjee, Goutami; Car, Suzana; Liu, Tongjun; Williams, Daniel L; Meza, Sarynna López; Walton, Jonathan D; Hodge, David B

2011-12-13

23

Alkaline Hydrolysis is an Effective Treatment Technology for RDX-Contaminated Groundwater  

SciTech Connect

Kinetics and treatability of alkaline hydrolysis were investigated in batch reactor and continuous flow-stirred tank reactor (CFSTR) for remediating groundwater contaminated with hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX). The batch system (pH 11 to 13, RDX 1 to 10 mg/L) achieved pseudo first-order RDX transformation rates in the range of 0.2 to 47.5 min-1, corresponding to 57.8 to 0.2 hrs of half-life period, respectively. In the CFSTR system (pH 11 to 11.9, HRT 0.54 to 2 days), the best alkaline RDX transformation was achieved a 99% RDX removal with the longest HRT and the highest reaction pH. Formate ({approx}2 M/M RDXremoved) and nitrite ({approx}0.2 M/M RDXremoved) were produced as the major hydrolysates, indicative of a simultaneous transformation mechanism by RDX ring cleavage and ring nitrogen elimination. The net OH- demand was found to be 1.5, 390 and 130 M OH-/M RDXremoved at the pH of 11.9, 11.5 and 11.0, respectively, in the CFSTR system.

Hqang, Snagchul; Felt, Deborah R.; Bouwer, Edward J.; Brooks, Michael C.; Larson, Steven L.; Davis, Jeffrey L.

2003-03-26

24

Alkaline Hydrolysis/Polymerization of 2,4,6-Trinitrotoluene: Characterization of Products by 13C and 15N NMR  

USGS Publications Warehouse

Alkaline hydrolysis has been investigated as a nonbiological procedure for the destruction of 2,4,6-trinitrotoluene (TNT) in explosives contaminated soils and munitions scrap. Nucleophilic substitutions of the nitro and methyl groups of TNT by hydroxide ion are the initial steps in the alkaline degradation of TNT. Potential applications of the technique include both in situ surface liming and ex situ alkaline treatment of contaminated soils. A number of laboratory studies have reported the formation of an uncharacterized polymeric material upon prolonged treatment of TNT in base. As part of an overall assessment of alkaline hydrolysis as a remediation technique, and to gain a better understanding of the chemical reactions underlying the hydrolysis/polymerization process, the soluble and precipitate fractions of polymeric material produced from the calcium hydroxide hydrolysis of unlabeled and 15N-labeled TNT were analyzed by elemental analysis and 13C and 15N nuclear magnetic resonance spectroscopy. Spectra indicated that reactions leading to polymerization included nucleophilic displacement of nitro groups by hydroxide ion, formation of ketone, carboxyl, alcohol, ether, and other aliphatic carbons, conversion of methyl groups to diphenyl methylene carbons, and recondensation of aromatic amines and reduced forms of nitrite, including ammonia and possibly hydroxylamine, into the polymer. Compared to the distribution of carbons in TNT as 14% sp 3- and 86% sp2-hybridized, the precipitate fraction from hydrolysis of unlabeled TNT contained 33% sp3- and 67% sp 2-hybridized carbons. The concentration of nitrogen in the precipitate was 64% of that in TNT. The 15N NMR spectra showed that, in addition to residual nitro groups, forms of nitrogen present in the filtrate and precipitate fractions include aminohydroquinone, primary amide, indole, imine, and azoxy, among others. Unreacted nitrite was recovered in the filtrate fraction. The toxicities and susceptibilities to microbial or chemical degradation of the polymeric materials remain unknown.

Thorn, K. A.; Thorne, P. G.; Cox, L. G.

2004-01-01

25

Enhanced osteogenic activity of a poly(butylene succinate)/calcium phosphate composite by simple alkaline hydrolysis.  

PubMed

Bone engineering offers the prospect of alternative therapies for clinically relevant skeletal defects. Poly(butylene succinate) (PBSu) is a biodegradable and biocompatible polyester which may possess some limitations in clinical use due to its hydrophobicity. In order to overcome these limitations and increase the bioactivity, a simple and convenient surface hydrolysis of PBSu, PBSu/hydroxyapatite and PBSu/?-tricalcium phosphate (TCP) films was performed. The resulting surfaces (i.e., HPBSu, HPBSu/HA and HPBSu/TCP) were tested for their physicochemical property, biocompatibility and osteogenic potency. The results showed that surface hydrolysis significantly increased surface roughness and hydrophilicity of the composites, with the HPBSu/TCP possessing the most pronounced results. All the materials appeared to be biocompatible and supported in vitro growth and osteoblast differentiation of hMSCs, and the alkaline hydrolysis significantly enhanced the hMSC cell proliferation and the osteogenic potency of PBSu/TCP compared with the non-hydrolyzed sample. In conclusion, the HPBSu/TCP possessed better hydrophilicity, biocompatibility and osteogenic potency in vitro, suggesting that this simple and convenient alkaline hydrolysis could be used to augment the biological property of PBSu-based composites for bone engineering in vivo. PMID:24057872

Arphavasin, Suphakit; Singhatanadgit, Weerachai; Ngamviriyavong, Patcharee; Janvikul, Wanida; Meesap, Preeyapan; Patntirapong, Somying

2013-09-20

26

Inorganic nanofibers with tailored placement of nanocatalysts for hydrogen production via alkaline hydrolysis of glucose  

NASA Astrophysics Data System (ADS)

Monoaxial silica nanofibers containing iron species as well as coaxial nanofibers with a pure silica core and a silica shell containing high concentrations of iron nanocrystals were fabricated via electrospinning precursor solutions, followed by thermal treatment. Tetraethyl-orthosilicate (TEOS) and iron nitrate (Fe(NO3)3) were used as the precursors for the silica and iron phases, respectively. Thermal treatments of as-spun precursor fibers were applied to generate nanocrystals of iron with various oxidation states (pure iron and hematite). Scanning electron microscopy (SEM), x-ray diffraction (XRD), and transmission electron microscopy (TEM) were used to probe the fiber morphology and crystal structures. The results indicated that the size, phase, and placement of iron nanocrystals can be tuned by varying the precursor concentration, thermal treatment conditions, and processing scheme. The resulting nanofiber/metal systems obtained via both monoaxial and coaxial electrospinning were applied as catalysts to the alkaline hydrolysis of glucose for the production of fuel gas. Differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and bulk weight change in a furnace with residual gas analysis (RGA) were used to evaluate the performance of the catalysts for various ratios of both Fe to Si, and catalyst to glucose, and the oxidation state of the iron nanocrystals. The product gas is composed of mostly H2 (>96 mol%) and CH4 with very low concentrations of CO2 and CO. Due to the clear separation of reaction temperature for H2 and CH4 production, pure hydrogen can be obtained at low reaction temperatures. Our coaxial approach demonstrates that placing the iron species selectively near the fiber surface can lead to two to three fold reduction in catalytic consumption compared to the monoaxial fibers with uniform distribution of catalysts.

Hansen, Nathaniel S.; Ferguson, Thomas E.; Panels, Jeanne E.; Alissa Park, Ah-Hyung; Lak Joo, Yong

2011-08-01

27

Specificity of hydrolysis of phytic acid by alkaline phytase from lily pollen  

Microsoft Academic Search

lily (Lilium longiflorum 1.) pollen is described. Structures of the intermediate inositol phosphates and the final product were estab- lished by a variety of nuclear magnetic resonance techniques ('H-, 31P-, and 3'P-'H-detected multiple quantum coherence spec- troscopy, and total correlation spectroscopy). On the basis of the structures identified we have proposed a scheme of hydrolysis of phytic acid. Initial hydrolysis

Laura Barrientos; Jonathan J. Scott; Pushpalatha P. N. Murthy

1994-01-01

28

Kinetics of hydrolysis and oxidation of carbon disulfide by hydrogen peroxide in alkaline medium and application to carbonyl sulfide  

SciTech Connect

Kinetic studies of the oxidation of carbon disulfide by hydrogen peroxide in alkaline medium were made spectrophotometrically. The reaction of CS/sub 2/ with OH/sup -/ ion was found to be rate controlling and proceeded by the formation of a dithiocarbonate complex. The major reaction product was sulfate with sulfur occurring as colloidal suspensions only at pH values less than 8. The formation of sulfate increased exponentially with time and was also found to be dependent on the rate of hydrolysis of CS/sub 2/. In addition, the production of sulfate showed large induction periods, suggesting either a complex mechanism or formation by secondary reactions. The results obtained for carbon disulfide were extended to carbonyl sulfide (OCS) oxidation in alkaline solutions. The removal of OCS (acid gas) from mixtures of gases by alkaline liquid absorbents (e.g. NaOH) and oxidation of subsequent solutions to sulfate is an important industrial practice. 42 references, 14 figures, 2 tables.

Adewuyi, Y.G.; Carmichael, G.R.

1987-02-01

29

Investigation of Unexpected Reaction Intermediates in the Alkaline Hydrolysis of Methyl 3,5-Dinitrobenzoate  

ERIC Educational Resources Information Center

|An experimental project aimed at identifying stable reaction intermediates is described. Initially, the studied reaction appears to involve the simple hydrolysis, by aqueous sodium hydroxide, of methyl 3,5-dinitrobenzoate dissolved in dimethyl sulfoxide. On mixing the substrates, however, the reaction mixture unexpectedly turns an intense red in…

Silva, Clesia C.; Silva, Ricardo O.; Navarro, Daniela M. A. F.; Navarro, Marcelo

2009-01-01

30

Pretreatment of cane bagasse with alkaline hydrogen peroxide for enzymatic hydrolysis of cellulose and ethanol fermentation  

Microsoft Academic Search

Pretreatment of the agrocellulosic waste, cane bagasse with alkaline hydrogen peroxide greatly enhances its susceptibility to enzymatic cellulolysis and thus the ethanol production from it. Various process conditions have been studied to optimize the enzymate effectiveness. These conditions include the contact time, the hydrogen peroxide concentration and the pretreatment temperature. Results obtained show, that about 50% of lignin and most

A. M. Azzam

1989-01-01

31

Alkaline hydrolysis of dimethyl terephthalate in the presence of [LiAl{sub 2}(OH){sub 6}]Cl.2H{sub 2}O  

SciTech Connect

The alkaline hydrolysis of dimethyl terephthalate (DMT) in the presence of [LiAl{sub 2}(OH){sub 6}]Cl has been investigated to demonstrate a possible application of anion exchange facility of layered double hydroxides (LDHs) to control chemical reactions. The results show that (i) in the alkaline hydrolysis of DMT in the presence of [LiAl{sub 2}(OH){sub 6}]Cl, most of the interlayer Cl{sup -} of [LiAl{sub 2}(OH){sub 6}]Cl is quickly replaced by OH{sup -} in the alkaline solution because the LDH host favors OH{sup -} more; (ii) the alkaline hydrolysis of DMT in the presence of [LiAl{sub 2}(OH){sub 6}]Cl is faster than the reaction of DMT and [LiAl{sub 2}(OH){sub 6}]OH; (iii) The hydrolysis of DMT in a buffer solution of pH{approx}8 takes longer time to reach equilibrium than the alkaline hydrolysis of DMT in the presence of [LiAl{sub 2}(OH){sub 6}]Cl. It is believed that the selective anion exchange chemistry of the LDH plays a key role in storage and controlled release of active reactant, that is, OH{sup -}, thus make the hydrolysis proceeds in a controlled way. - Graphical abstract: XRD patterns of the solid products of the alkaline hydrolysis of dimethyl terephthalate (DMT) in the presence of [LiAl{sub 2}(OH){sub 6}]Cl at 70 deg. C halted at different time, which shows that [LiAl{sub 2}(OH){sub 6}]Cl turns out to be [LiAl{sub 2}(OH){sub 6}]OH, and [LiAl{sub 2}(OH){sub 6}]{sub 2}TP forms gradually. In this reaction, the alkaline hydrolysis of DMT is controlled by replacement of Cl{sup -} in [LiAl{sub 2}(OH){sub 6}]Cl by OH{sup -}, and subsequent replacement of OH{sup -} in [LiAl{sub 2}(OH){sub 6}]OH by terephthalate anion.

Lei Lixu [Department of Chemistry and Chemical Engineering, Southeast University, Nanjing 210096 (China)]. E-mail: lixu.lei@seu.edu.cn1; Zhang Weifeng [Department of Chemistry and Chemical Engineering, Southeast University, Nanjing 210096 (China); Hu Meng [Department of Chemistry and Chemical Engineering, Southeast University, Nanjing 210096 (China); Zheng Hegen [State Key Laboratory of Coordination Chemistry, Nanjing 210093 (China)

2006-11-15

32

Pretreatment of cane bagasse with alkaline hydrogen peroxide for enzymatic hydrolysis of cellulose and ethanol fermentation  

SciTech Connect

Pretreatment of the agrocellulosic waste, cane bagasse with alkaline hydrogen peroxide greatly enhances its susceptibility to enzymatic cellulolysis and thus the ethanol production from it. Various process conditions have been studied to optimize the enzymate effectiveness. These conditions include the contact time, the hydrogen peroxide concentration and the pretreatment temperature. Results obtained show, that about 50% of lignin and most of hemicellulose content of can bagasse was solubilized, by 2% alkaline hydrogen peroxide at 30{sup 0}C within 8 h. The cellulose content was consequently increased from 42% in the original cane bagasse to 75% in the oxidized pulp. Saccharification of this pulp residue with cellulase from Trichorderma viride at 45{sup 0}C for 24 h, yielded glucose with 95% efficiency. The efficiency of ethanol production from the insoluble fraction with S. cervisiae was 90% compared to about 50% for untreated cane bagasse.

Azzam, A.M. (National Research Centre, Cairo (Egypt))

1989-01-01

33

Reduction and alkaline hydrolysis of 5-oxoindeno(1,2-b)pyridinium salts  

SciTech Connect

5,9b-dihydro derivatives of indeno(1,2-b)pyridine were obtained by the reduction of the corresponding 1,2-dimethyl-4-acryl-5-oxoindeno(1,2-b)pyridinium perchlorates. 1,2-dimethyl-3-ethoxycarbonyl-4-phenyl-5-oxoindeno(1,2-b)pyridinium perchlorate forms in alkaline medium with splitting, recyclization and deamination products.

Mutsenietse, D.Kh.; Zandersons, A.Z.; Lusis, V.K.; Dubur, G.Ya.

1987-07-01

34

Alkaline polyol pulping and enzymatic hydrolysis of softwood: effect of pulping severity and pulp properties on cellulase activity and overall sugar yield.  

PubMed

The saccharification of softwood using alkaline polyol pulping (AlkaPolP) and enzymatic hydrolysis was investigated. It will be demonstrated that the AlkaPolP process yields high quality pulps which can easily be hydrolyzed by cellulases. Temperature (180-230°C) and duration (15-60 min) of the alkaline glycerol pulping, expressed as pulping severity R0, were varied to find optimum reaction conditions. The obtained pulps were characterized regarding their residual lignin content, kappa number and crystallinity index. Thus, the dependencies of the conversion during enzymatic hydrolysis on severity, pulp composition and pulp characteristics could be observed. In further experiments it was investigated how the enzymatic hydrolysis is affected by pulp drying or by a reduction of enzyme loading. Up to 83% of the initial cellulose in wood and almost 97% of the cellulose in pulp were converted into glucose using cellulases from Trichoderma reesei and ?-glucosidase from Aspergillus niger. PMID:23500589

Hundt, Martin; Schnitzlein, Klaus; Schnitzlein, Michael G

2013-02-15

35

EFFECT OF ANATOMICAL FRACTIONATION ON THE ENZYMATIC HYDROLYSIS OF ACID AND ALKALINE PRETREATED CORN STOVER  

SciTech Connect

Due to concerns with biomass collection systems and soil sustainability there are opportunities to investigate the optimal plant fractions to collect for conversion. An ideal feedstock would require low severity pretreatment to release a maximum amount of sugar during enzymatic hydrolysis. Corn stover fractions were separated by hand and analyzed for glucan, xylan, acid soluble lignin, acid insoluble lignin, and ash composition. The stover fractions were also pretreated with either 0, 0.4, or 0.8% NaOH for 2 hours at room temperature, washed, autoclaved and saccharified. In addition, acid pretreated samples underwent simultaneous saccharification and fermentation (SSF) to ethanol. In general, the two pretreatments produced similar trends with cobs, husks, and leaves responding best to the pretreatments, the tops of stalks responding slightly less, and the bottom of the stalks responding the least. For example, corn husks pretreated with 0.8% NaOH released over 90% (standard error of 3.8%) of the available glucan, while only 45% (standard error of 1.1%) of the glucan was produced from identically treated stalk bottoms. Estimates of the theoretical ethanol yield using acid pretreatment followed by SSF were 65% (standard error of 15.9%) for husks and 29% (standard error of 1.8%) for stalk bottoms. This suggests that integration of biomass collection systems to remove sustainable feedstocks could be integrated with the processes within a biorefinery to minimize overall ethanol production costs.

K. B. Duguid; M. D. Montross; C. W. Radtke; C. L. Crofcheck; L. M. Wendt; S. A. Shearer

2009-11-01

36

Surface potential and osteoblast attraction to calcium phosphate compounds is affected by selected alkaline hydrolysis processing.  

PubMed

This study examines the link(s) between the suspension behavior of calcium deficient apatites (CDAs) and biphasic calcium phosphate (BCP), as measured by the zeta-potential, with respect to both whole bone and osteoblasts. CDA is fabricated by hydrolyzing an acidic CaP such as dicalcium diphosphate dihydrate (DCPD; CaHPO4.2H2O) and has a structure and composition close to bone apatite. Sintering CDA results in the formation of BCP ceramics consisting of mixtures of hydroxyapatite (HA) and beta-tricalcium phosphate (beta-TCP), with the HA/beta-TCP weight ratio proportional to the Ca/P ratio of CDA. The choice of the base for the DCPD hydrolysis allows various ionic partial substitution of the formed CDA. Na for Ca partial substitution is of interest because of the resulting improvement in mechanical properties of the resulting BCP ceramics and NH4OH was used as a negative control. The zeta-potential was measured for these materials and the stability of the ceramic to bone interaction calculated. zeta-potential values decrease for CDA(NH4OH) versus CDA(NaOH) and increase for BCP(NH4OH) versus BCP(NaOH). While results of these analyses indicate that NH4OH and NaOH processed CDA and BCP will likely yield osteoblast attachment in vivo, differences in the zeta-potentials may explain varying degrees of cell attachment. PMID:15477734

Smith, I O; Baumann, M J; Obadia, L; Bouler, J-M

2004-08-01

37

Alkaline polyol pulping and enzymatic hydrolysis of hardwood: effect of pulping severity and pulp composition on cellulase activity and overall sugar yield.  

PubMed

The saccharification of beech wood using alkaline polyol pulping (AlkaPolP) and enzymatic hydrolysis was investigated. It will be demonstrated that the AlkaPolP process yields high quality pulps which can easily be hydrolyzed by cellulases. In order to find optimum reaction conditions chips of Fagus sylvatica were pretreated by alkaline glycerol at temperatures between 190 and 230 °C for 15, 20, and 25 min. The impacts of temperature and time were expressed using a severity factor R0. The dependencies of the conversion during enzymatic hydrolysis on severity, pulp yield, delignification and pulp composition are shown. In further experiments it was investigated if the sugar yields can be increased by the application of ultrasound or surfactants before enzyme addition. Up to 95% of the initial cellulose in wood were converted into glucose using cellulases from Trichoderma reesei and ?-glucosidase from Aspergillus niger. PMID:23570715

Hundt, Martin; Schnitzlein, Klaus; Schnitzlein, Michael G

2013-03-07

38

Mechanisms and kinetics of alkaline hydrolysis of the energetic nitroaromatic compounds 2,4,6-trinitrotoluene (TNT) and 2,4-dinitroanisole (DNAN).  

PubMed

The environmental impacts of energetic compounds can be minimized through the design and selection of new energetic materials with favorable fate properties. Building predictive models to inform this process, however, is difficult because of uncertainties and complexities in some major fate-determining transformation reactions such as the alkaline hydrolysis of energetic nitroaromatic compounds (NACs). Prior work on the mechanisms of the reaction between NACs and OH(-) has yielded inconsistent results. In this study, the alkaline hydrolysis of 2,4,6-trinitrotoluene (TNT) and 2,4-dinitroanisole (DNAN) was investigated with coordinated experimental kinetic measurements and molecular modeling calculations. For TNT, the results suggest reversible formation of an initial product, which is likely either a Meisenheimer complex or a TNT anion formed by abstraction of a methyl proton by OH(-). For DNAN, the results suggest that a Meisenheimer complex is an intermediate in the formation of 2,4-dinitrophenolate. Despite these advances, the remaining uncertainties in the mechanisms of these reactions-and potential variability between the hydrolysis mechanisms for different NACs-mean that it is not yet possible to generalize the results into predictive models (e.g., quantitative structure-activity relationships, QSARs) for hydrolysis of other NACs. PMID:23373810

Salter-Blanc, Alexandra J; Bylaska, Eric J; Ritchie, Julia J; Tratnyek, Paul G

2013-02-22

39

Determination of Tryptophan with HPLC after Alkaline Hydrolysis in Autoclave using ?-methyl-tryptophan as Internal Standard  

Microsoft Academic Search

A method for determination of tryptophan in feeding stuffs is described. The hydrolysis is carried out on a sample containing 10 mg nitrogen using 25 ml NaOH 4.2 mol\\/l at 110°C for 16 hours in an autoclave. ?-methyl-tryptophan is used as internal standard. The tryptophan and the internal standard are determined by using HPLC with fluorescence detection. When analysing three

Steen Bech-Andersen

1991-01-01

40

Improved gas chromatographic method for determination of daminozide by alkaline hydrolysis and 2-nitrobenzaldehyde derivatization and survey results of daminozide in agricultural products.  

PubMed

An improved method was developed for the quantitative determination of daminozide. This new method combines the alkaline hydrolysis and distillation steps of the PAM II method for daminozide with the derivatization, cleanup, and gas chromatographic determination steps of the Wright method for unsymmetrical dimethyl hydrazine (UDMH). The minimum detectable level is 0.05 ppm. Recoveries range from 85 to 110% when daminozide is added at 0.1 to 1.0 ppm, and are generally 40% at the 0.05 ppm level. A variety of domestic and imported products were analyzed by this improved method and daminozide was detected in 33 of the 98 samples analyzed. Levels detected ranged from a trace amount to 0.80 ppm. The identity of UDMH hydrazone was confirmed by mass spectrometry in many samples, thus confirming the presence of daminozide. Two samples containing daminozide were analyzed independently by a second laboratory and the findings were closely duplicated. PMID:2211471

Steinbrecher, K; Saxton, W L; Oehler, G A

41

Stereospecific synthesis of 16. cap alpha. -hydroxy-17-oxo steroids by controlled alkaline hydrolysis of corresponding 16-bromo 17-ketones and its reaction mechanism  

SciTech Connect

Synthesis of 16..cap alpha..-hydroxy-17-oxo steroids and 3..beta..,16..cap alpha..-dihydroxy-5-17-oxoandrosten-3-yl sulfate from 16..cap alpha..-bromo-17-oxo steroids and the reaction mechanism of the controlled alkaline hydrolysis are described. Treatment of the bromo ketones with NaOH in aqueous DMF gave the 16..cap alpha..-hydroxy 17-ketones stereoselectively in 95% yield without formation of other ketols. The sodium salt of 3-sulfate was also obtained in one step in 85% yield from the corresponding bromo ketone. Isotope-labeling experiments and time-course studies showed that equilibration between the 15-bromo epimers occurs by the reaction mechanism described in this report. The 16..beta..-morpholino derivaive obtained by reaction with morpholine was shown to be an isomerized product of the 16..cap alpha.. isomer which is produced also by S/sub N/2 displacement of the 16..beta..-bromine. The mechanism of ketol rearrangement to the 17..beta..-hydroxy-16-oxo compound was found to involve a hydration to the carbonyl function. The new hydration dehydration mechanism is proposed for the ketol rearrangement.

Numazawa, M. (Tohoku Coll. of Pharmacy, Sendai, Japan); Nagaoka, M.; Osawa, Y.

1982-10-08

42

Analysis of 4-aminobiphenyl-DNA adducts in human urinary bladder and lung by alkaline hydrolysis and negative ion gas chromatography-mass spectrometry.  

PubMed Central

Analysis of carcinogen-DNA adducts has been regarded as a useful means of assessing human exposure to chemical carcinogens. We have established a method for quantitation of 4-aminobiphenyl (4-ABP)-DNA adducts by alkaline hydrolysis and gas chromatography with negative ion chemical ionization mass spectrometry (GC-NICI-MS). Aliquots of DNA (typically 100 micrograms/ml) were spiked with an internal standard, d9-4-ABP, and were hydrolyzed in 0.05 N NaOH at 130 degrees C overnight. The liberated 4-ABP was extracted with hexane and derivatized using pentafluoropropionic anhydride in trimethylamine for 30 min at room temperature prior to GC-NICI-MS. With in vitro [3H]N-hydroxy-4-ABP modified DNA standards, we observed 59 +/- 7% (n = 9) recovery of the 4-ABP and a linear correlation between hydrolyzed 4-ABP and the adduct levels ranging from about 1 in 10(8) to 1 in 10(4) nucleotides (r = 0.999, n = 9). The method was further validated by comparison of the results with that obtained by the 32P-postlabeling method. There was excellent agreement (r = 0.994, p < 0.001) between the two methods for quantitation of the adduct in eight samples of Salmonella typhimurium DNA treated with 4-ABP and rat liver S9, although the 32P-postlabeling method gave slightly higher values. The DNA adducts in 11 human lung and 8 urinary bladder mucosa specimens were then determined by our GC-NICI-MS method. The adduct levels were found to be < 0.32 to 49.5 adducts per 10(8) nucleotides in the lungs and < 0.32 to 3.94 adducts per 10(8) nucleotides in the bladder samples.(ABSTRACT TRUNCATED AT 250 WORDS) Images Figure 4. A Figure 4. B

Lin, D; Lay, J O; Bryant, M S; Malaveille, C; Friesen, M; Bartsch, H; Lang, N P; Kadlubar, F F

1994-01-01

43

Alkaline hydrolysis of the cyclic nitramine explosives RDX, HMX, and CL-20: new insights into degradation pathways obtained by the observation of novel intermediates.  

PubMed

Hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX, I) and octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) hydrolyze at pH > 10 to form end products including NO2-, HCHO, HCOOH, NH3, and N2O, but little information is available on intermediates, apart from the tentatively identified pentahydro-3,5-dinitro-1,3,5-triazacyclohex-1-ene (II). Despite suggestions that RDX and HMX contaminated groundwater could be economically treated via alkaline hydrolysis, the optimization of such a process requires more detailed knowledge of intermediates and degradation pathways. In this study, we hydrolyzed the monocyclic nitramines RDX, MNX (hexahydro-1-nitroso-3,5-dinitro-1,3,5-triazine), and HMX in aqueous solution (pH 10-12.3) and found that nitramine removal was accompanied by formation of 1 molar equiv of nitrite and the accumulation of the key ring cleavage product 4-nitro-2,4-diazabutanal (4-NDAB, O2NNHCH2NHCHO). Most of the remaining C and N content of RDX, MNX, and HMX was found in HCHO, N2O, HCOOH, and NH3. Consequently, we selected RDX as a model compound and hydrolyzed it in aqueous acetonitrile solutions (pH 12.3) in the presence and absence of hydroxypropyl-beta-cyclodextrin (HP-beta-CD) to explore other early intermediates in more detail. We observed a transient LC-MS peak with a [M-H] at 192 Da that was tentatively identified as 4,6-dinitro-2,4,6-triaza-hexanal (O2NNHCH2NNO2CH2NHCHO, III) considered as the hydrolyzed product of II. In addition, we detected another novel intermediate with a [M-H] at 148 Da that was tentatively identified as a hydrolyzed product of III, namely, 5-hydroxy-4-nitro-2,4-diaza-pentanal (HOCH2NNO2CH2NHCHO, IV). Both III and IV can act as precursors to 4-NDAB. In the case of the polycyclic nitramine 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane (CL-20), denitration (two NO2-) also led to the formation of HCOOH, NH3, and N2O, but neither HCHO nor 4-NDAB were detected. The results provide strong evidence that initial denitration of cyclic nitramines in water is sufficient to cause ring cleavage followed by spontaneous decomposition to form the final products. PMID:12775055

Balakrishnan, Vimal K; Halasz, Annamaria; Hawari, Jalal

2003-05-01

44

PHTHALATE ESTER HYDROLYSIS: LINEAR FREE ENERGY RELATIONSHIPS  

EPA Science Inventory

Alkaline hydrolysis rate constants were measured for dimethyl, diethyl, di-n-butyl, di-iso-butyl, and di-(2-ethylhexyl) phthalate esters in water. A linear free energy relationship (LFER) was established for estimating alkaline hydrolysis rate constants for other phthalate esters...

45

QM/MM analysis suggests that Alkaline Phosphatase (AP) and Nucleotide pyrophosphatase/phosphodiesterase slightly tighten the transition state for phosphate diester hydrolysis relative to solution: implication for catalytic promiscuity in the AP superfamily  

PubMed Central

Several members of the Alkaline Phosphatase (AP) superfamily exhibit a high level of catalytic proficiency and promiscuity in structurally similar active sites. A thorough characterization of the nature of transition state for different substrates in these enzymes is crucial for understanding the molecular mechanisms that govern those remarkable catalytic properties. In this work, we study the hydrolysis of a phosphate diester, MpNPP?, in solution, two experimentally well-characterized variants of AP (R166S AP, R166S/E322Y AP) and wild type Nucleotide pyrophosphatase/phosphodiesterase (NPP) by QM/MM calculations in which the QM method is an approximate density functional theory previously parameterized for phosphate hydrolysis (SCC-DFTBPR). The general agreements found between these calculations and available experimental data for both solution and enzymes support the use of SCC-DFTBPR/MM for a semi-quantitative analysis of the catalytic mechanism and nature of transition state in AP and NPP. Although phosphate diesters are cognate substrates for NPP but promiscuous substrates for AP, the calculations suggest that their hydrolysis reactions catalyzed by AP and NPP feature similar synchronous transition states that are slightly tighter in nature compared to that in solution, due in part to the geometry of the bimetallic zinc motif. Therefore, this study provides the first direct computational support to the hypothesis that enzymes in the AP superfamily catalyze cognate and promiscuous substrates via similar transition states to those in solution. Our calculations do not support the finding of recent QM/MM studies by López-Canut and coworkers, who suggested that the same diester substrate goes through a much looser transition state in NPP/AP than in solution, a result likely biased by the large structural distortion of the bimetallic zinc site in their simulations. Finally, our calculations for different phosphate diester orientations and phosphorothioate diesters highlight that the interpretation of thio-substitution experiments is not always straightforward.

Hou, Guanhua

2011-01-01

46

Inclusion of the insecticide fenitrothion in dimethylated-?-cyclodextrin: unusual guest disorder in the solid state and efficient retardation of the hydrolysis rate of the complexed guest in alkaline solution  

PubMed Central

Summary An anhydrous 1:1 crystalline inclusion complex between the organophosphorus insecticide fenitrothion [O,O-dimethyl O-(3-methyl-4-nitrophenyl)phosphorothioate] and the host compound heptakis(2,6-di-O-methyl)-?-cyclodextrin (DIMEB) was prepared and its structure elucidated by single-crystal X-ray diffraction. This revealed two independent host molecules in the asymmetric unit. In one of these, the cavity is occupied by two disordered guest components (distinguishable as rotamers with respect to the P–OAr bond) while in the other, three distinct guest components with site-occupancies 0.44, 0.29 and 0.27 appear, the last having a reversed orientation relative to all the other components. Kinetic studies of the alkaline hydrolysis of fenitrothion in the presence of DIMEB showed a remarkable reduction of 84% in the rate of this reaction relative to that for the free substrate, a value exceeding those previously attained with the native hosts, ?- and ?-cyclodextrin, and fully methylated ?-cyclodextrin.

Cruickshank, Dyanne L; Rougier, Natalia M; Vico, Raquel V; Bourne, Susan A

2013-01-01

47

ABIOTIC HYDROLYSIS OF SORBED PESTICIDES  

EPA Science Inventory

The hydrolysis of pesticides that are sorbed to sterilized natural sediments has been investigated in aqueous systems at acid, neutral and alkaline pH's. The results show that the rate constants of pH independent ('neutral') hydrolyses are the same within experimental uncertainti...

48

Abiotic Hydrolysis of Sorbed Pesticides.  

National Technical Information Service (NTIS)

The hydrolysis of pesticides that are sorbed to sterilized natural sediments has been investigated in aqueous systems at acid, neutral and alkaline pH's. The results show that the rate constants of pH independent ('neutral') hydrolyses are the same within...

D. L. Macalady N. L. Wolfe

1984-01-01

49

Alkaline Hydrolysis/Biodegradation of Nitrocellulose Fines.  

National Technical Information Service (NTIS)

Cellulose nitrate constitutes an important industrial feedstock, with applications ranging from fingernail polish and photographic films, to explosives. The high level of nitration required for these explosive materials creates a significant environmental...

B. J. Kim J. E. Alleman D. M. Quivey

1998-01-01

50

Alkalinity Protocol  

NSDL National Science Digital Library

This site from GLOBE describes an exercise in which students learn the correct way to measure the alkalinity of water. Topics include definitions of alkaline and pH, and the importance of alkalinity in buffering acidic additions to water. Also included are lab and field guides, and examples of student research.

Globe

51

Adsorption of albumin, collagen, and fibronectin on the surface of poly(hydroxybutyrate-hydroxyvalerate) (PHB/HV) and of poly (epsilon-caprolactone) (PCL) films modified by an alkaline hydrolysis and of poly(ethylene terephtalate) (PET) track-etched membranes.  

PubMed

The effect of alkaline hydrolysis on several surface properties of poly(hydroxybutyrate-hydroxyvalerate) (92/8) (PHB/HV) and poly(epsilon-caprolactone) (PCL) films and of poly(ethylene terephtalate) (PET) track-etched membranes have been characterized, as well as the adsorption of three proteins normally encountered by mammalian cells in vivo, namely albumin, collagen, and fibronectin. The water contact angle decreases and the number of -COOH functions accessible to a chemical reaction at the surface of PCL increases with alkaline hydrolysis. Analysis by atomic force microscopy pictures reveals a change in surface morphology. The modifications of surface properties are correlated with a two times increase of the adsorption of three radiolabelled proteins. The hydrolysis results in a slight increase in the water contact angle of one face of the PHB/HV film and a sharp increase in the number of -COOH functions. Important morphology changes are also induced. The adsorption of the radiolabelled proteins is almost 100 times higher on the hydrolyzed polymer than on the native surface. The increase in hydrophilicity of different PET batches correlates to an increase in the number of -COOH functions. Nevertheless, the surface chemical composition and rugosity are constant and no significant difference in the amount of radiolabelled fibronectin adsorbed on the different surfaces is detectable. In conclusion, the effect of hydrolysis on the surface properties of each of the polyesters studied as well as the proteins adsorption on the different surfaces are different. The results strongly support the hypothesis that, in the system studied, parameters other than hydrophilicity influence protein adsorption: the main parameters that might play a role are the total surface area accessible to the proteins, as well as the surface chemical composition. PMID:9860170

Rouxhet, L; Duhoux, F; Borecky, O; Legras, R; Schneider, Y J

1998-01-01

52

Effect of hydrolysis on identifying prenatal cannabis exposure  

PubMed Central

Identification of prenatal cannabis exposure is important due to potential cognitive and behavioral consequences. A two-dimensional gas chromatography–mass spectrometry method for cannabinol, ?9-tetrahydrocannabinol (THC), 11-hydroxy-THC (11-OH-THC), 8?,11-dihydroxy-THC, and 11-nor-9-carboxy-THC (THCCOOH) quantification in human meconium was developed and validated. Alkaline, enzymatic, and enzyme–alkaline tandem hydrolysis conditions were optimized with THC- and THCCOOH-glucuronide reference standards. Limits of quantification ranged from 10 to 15 ng/g, and calibration curves were linear to 500 ng/g. Bias and intra-day and inter-day imprecision were <12.3%. Hydrolysis efficiencies were analyte-dependent; THC-glucuronide was effectively cleaved by enzyme, but not base. Conversely, THCCOOH-glucuronide was most sensitive to alkaline hydrolysis. Enzyme–alkaline tandem hydrolysis maximized efficiency for both glucuronides. Identification of cannabinoid-positive meconium specimens nearly doubled following alkaline and enzyme–alkaline hydrolysis. Although no 11-OH-THC glucuronide standard is available, enzymatic hydrolysis improved 11-OH-THC detection in authentic specimens. Maximal identification of cannabis-exposed neonates and the widest range of cannabis biomarkers are achieved with enzyme–alkaline tandem hydrolysis.

Gray, Teresa R.; Barnes, Allan J.

2011-01-01

53

Theoretical study on oxygen exchange accompanying alkaline hydrolysis of esters and amides. The role of water for the exchange reaction 1 Dedicated to Professor Keiji Morokuma in celebration of his 65th birthday. 1  

Microsoft Academic Search

The hydrolysis of esters and amides accompanies a fast reaction, which results in exchange of carbonyl 18O to 16O coming from solvent water. The present study considered two paths as the oxygen exchange mechanism. One, Path 1 called the direct path, is the mechanism that a proton of the OH fragment directly moves from the OH to the 18O fragment

Kenzi Hori; Yuji Hashitani; Yuji Kaku; Katsutoshi Ohkubo

1999-01-01

54

Simultaneous GC-EI-MS Determination of ?9-Tetrahydrocannabinol, 11-Hydroxy-?9-Tetrahydrocannabinol, and 11-nor-9-Carboxy-?9-Tetrahydrocannabinol in Human Urine Following Tandem Enzyme-Alkaline Hydrolysis  

PubMed Central

A sensitive and specific method for extraction and quantification of ?9-tetrahydrocannabinol (THC), 11-hydroxy-?9-tetrahydrocannabinol (11-OH-THC), and 11-nor-9-carboxy-?9-tetrahydrocannabinol (THCCOOH) in human urine was developed and fully validated. To ensure complete hydrolysis of conjugates and capture of total analyte content, urine samples were hydrolyzed by two methods in series. Initial hydrolysis was with Escherichia coli ?-glucuronidase (Type IX–A) followed by a second hydrolysis utilizing 10N NaOH. Specimens were adjusted to pH 5?6.5, treated with acetonitrile to precipitate protein, and centrifuged, and the supernatants were subjected to solid-phase extraction. Extracted analytes were derivatized with BSTFA and quantified by gas chromatography–mass spectrometry with electron impact ionization. Standard curves were linear from 2.5 to 300 ng/mL. Extraction efficiencies were 57.0?59.3% for THC, 68.3?75.5% for 11-OH-THC, and 71.5?79.7% for THCCOOH. Intra- and interassay precision across the linear range of the assay ranged from 0.1 to 4.3% and 2.6 to 7.4%, respectively. Accuracy was within 15% of target concentrations. This method was applied to the analysis of urine specimens collected from individuals participating in controlled administration cannabis studies, and it may be a useful analytical procedure for determining recency of cannabis use in forensic toxicology applications.

Abraham, Tsadik T.; Lowe, Ross H.; Pirnay, Stephane O.; Darwin, William D.; Huesti, Marilyn A.

2009-01-01

55

Simultaneous GC-EI-MS determination of Delta9-tetrahydrocannabinol, 11-hydroxy-Delta9-tetrahydrocannabinol, and 11-nor-9-carboxy-Delta9-tetrahydrocannabinol in human urine following tandem enzyme-alkaline hydrolysis.  

PubMed

A sensitive and specific method for extraction and quantification of Delta(9)-tetrahydrocannabinol (THC), 11-hydroxy-Delta(9)-tetrahydrocannabinol (11-OH-THC), and 11-nor-9-carboxy-Delta(9)-tetrahydrocannabinol (THCCOOH) in human urine was developed and fully validated. To ensure complete hydrolysis of conjugates and capture of total analyte content, urine samples were hydrolyzed by two methods in series. Initial hydrolysis was with Escherichia coli beta-glucuronidase (Type IX-A) followed by a second hydrolysis utilizing 10N NaOH. Specimens were adjusted to pH 5-6.5, treated with acetonitrile to precipitate protein, and centrifuged, and the supernatants were subjected to solid-phase extraction. Extracted analytes were derivatized with BSTFA and quantified by gas chromatography-mass spectrometry with electron impact ionization. Standard curves were linear from 2.5 to 300 ng/mL. Extraction efficiencies were 57.0-59.3% for THC, 68.3-75.5% for 11-OH-THC, and 71.5-79.7% for THCCOOH. Intra- and interassay precision across the linear range of the assay ranged from 0.1 to 4.3% and 2.6 to 7.4%, respectively. Accuracy was within 15% of target concentrations. This method was applied to the analysis of urine specimens collected from individuals participating in controlled administration cannabis studies, and it may be a useful analytical procedure for determining recency of cannabis use in forensic toxicology applications. PMID:17988462

Abraham, Tsadik T; Lowe, Ross H; Pirnay, Stephane O; Darwin, William D; Huestis, Marilyn A

2007-10-01

56

Alkaline battery  

US Patent & Trademark Office Database

An alkaline battery comprising a positive electrode, a negative electrode, a separator disposed between the positive electrode and the negative electrode; and an alkaline electrolyte, wherein the positive electrode includes manganese dioxide and graphite; the cumulative pore volume of pores with diameters of 3 to 5 nm in the manganese dioxide is X (cm.sup.3/g), and the weight loss rate of the manganese dioxide when heated from 150 to 400.degree. C. is Y (%), X and Y satisfying 0.005.ltoreq.X.ltoreq.0.011, 3.4.ltoreq.Y.ltoreq.3.9, and -16.7X+3.58.ltoreq.Y.ltoreq.66.7X+3.17; the negative electrode includes zinc; and the alkaline electrolyte includes an aqueous potassium hydroxide solution.

Nunome; Jun (Kyoto, JP); Kato; Fumio (Osaka, JP); Shimamura; Harunari (Osaka, JP)

2011-11-01

57

Hydrolysis Kinetics of Secoisolariciresinol Diglucoside Oligomers from Flaxseed  

Microsoft Academic Search

Flaxseed is the richest dietary source of the lignan secoisolariciresinol diglucoside (SDG) and contains the largest amount of SDG oligomers, which are often hydrolyzed to break the ester linkages for the release of SDG and the glycosidic bonds for the release of secoisolariciresinol (SECO). The alkaline hydrolysis reaction kinetics of SDG oligomers from flaxseed and the acid hydrolysis process of

Jian-Ping Yuan; Xin Li; Shi-Ping Xu; Jiang-Hai Wang; Xin Liu

2008-01-01

58

O-Carbonyl-Assisted Alkaline Hydrolyses of Methyl Benzoates.  

National Technical Information Service (NTIS)

The rates of alkaline hydrolysis of methyl 6-methyl-2-benzoylbenzoate, methyl 6-methyl-2-acetylbenzoate, methyl 6-chloro-2-benzoylbenzoate, methyl 6-chloro-2-acetylbenzoate, and the 6-unsubstituted analogs have been measured. In each case the 6-substitute...

M. S. Newman A. L. Leegwater

1968-01-01

59

CARBARYL, PROPHAM AND CHLORPROPHAM: A COMPARISON OF THE RATES OF HYDROLYSIS AND PHOTOLYSIS WITH THE RATE OF BIOLYSIS  

EPA Science Inventory

Alkaline hydrolysis half-lives, based on second-order alkaline hydrolysis rate constants, for carbaryl, propham (IPC), and chlorpropham (CIPC) at pH 9 (27 degrees) are 0.15>1 x 10 to the 4th power days, and >1 x 10 to the 4th power days, respectively. The direct photolysis half-l...

60

The hydrolysis of carbonyl sulfide at low temperature: a review.  

PubMed

Catalytic hydrolysis technology of carbonyl sulfide (COS) at low temperature was reviewed, including the development of catalysts, reaction kinetics, and reaction mechanism of COS hydrolysis. It was indicated that the catalysts are mainly involved metal oxide and activated carbon. The active ingredients which can load on COS hydrolysis catalyst include alkali metal, alkaline earth metal, transition metal oxides, rare earth metal oxides, mixed metal oxides, and nanometal oxides. The catalytic hydrolysis of COS is a first-order reaction with respect to carbonyl sulfide, while the reaction order of water changes as the reaction conditions change. The controlling steps are also different because the reaction conditions such as concentration of carbonyl sulfide, reaction temperature, water-air ratio, and reaction atmosphere are different. The hydrolysis of carbonyl sulfide is base-catalyzed reaction, and the force of the base site has an important effect on the hydrolysis of carbonyl sulfide. PMID:23956697

Zhao, Shunzheng; Yi, Honghong; Tang, Xiaolong; Jiang, Shanxue; Gao, Fengyu; Zhang, Bowen; Zuo, Yanran; Wang, Zhixiang

2013-07-15

61

The Hydrolysis of Carbonyl Sulfide at Low Temperature: A Review  

PubMed Central

Catalytic hydrolysis technology of carbonyl sulfide (COS) at low temperature was reviewed, including the development of catalysts, reaction kinetics, and reaction mechanism of COS hydrolysis. It was indicated that the catalysts are mainly involved metal oxide and activated carbon. The active ingredients which can load on COS hydrolysis catalyst include alkali metal, alkaline earth metal, transition metal oxides, rare earth metal oxides, mixed metal oxides, and nanometal oxides. The catalytic hydrolysis of COS is a first-order reaction with respect to carbonyl sulfide, while the reaction order of water changes as the reaction conditions change. The controlling steps are also different because the reaction conditions such as concentration of carbonyl sulfide, reaction temperature, water-air ratio, and reaction atmosphere are different. The hydrolysis of carbonyl sulfide is base-catalyzed reaction, and the force of the base site has an important effect on the hydrolysis of carbonyl sulfide.

Zhao, Shunzheng; Yi, Honghong; Tang, Xiaolong; Jiang, Shanxue; Gao, Fengyu; Zhang, Bowen; Zuo, Yanran; Wang, Zhixiang

2013-01-01

62

Acid Hydrolysis of Wood.  

National Technical Information Service (NTIS)

A series of investigations into the acid hydrolysis of pinus radiata (Monterey pine) and the results therefrom are described. Main objectives of the investigation were to establish, using the most promising routes, the conditions of hydrolysis that would ...

A. L. Titchener B. K. Guha

1981-01-01

63

Hydrolysis of Bromodifluoromethyltriphenylphosphonium Bromide.  

National Technical Information Service (NTIS)

Hydrolysis of Ph3P(+)CFBr2Br(-) afforded a high yield of dibromofluoromethane and triphenylphosphine oxide. Hydrolysis in the presence of a radioactive isotope of bromine gave evidence that the mechanism of this reaction proceeds via the dibromofluorometh...

R. M. Flynn R. G. Manning R. M. Kessler

1981-01-01

64

Dephosphorylation of sodium caseinate, enzymatically hydrolyzed casein and casein phosphopeptides by intestinal alkaline phosphatase: implications for iron availability  

Microsoft Academic Search

Clusters of phosphoserine residues in casein bind iron with high affinity. Casein inhibits iron absorption in humans but partial hydrolysis of casein prior to ingestion diminishes this inhibition. The objective of this study was to test two hypotheses: 1. Partial hydrolysis of the peptide bonds in casein exposes phosphoserine residues to attack by intestinal alkaline phosphatase (IAP). 2. Hydrolysis of

Andrew C. Yeung; Raymond P. Glahn; Dennis D. Miller

2001-01-01

65

Mechanism of hydrolysis of a novel indolocarbazole topoisomerase I inhibitor.  

PubMed

The degradation kinetics and reaction product profile of the antitumor agent 1 in aqueous solution was studied. Hydrolysis of the pendant imide ring of 1 is the primary mode of thermal degradation in aqueous solution, and the pH rate profile of 1 has a V-shape indicating that hydrolysis of the imide ring can be catalyzed by either acid or base. Hydrolysis of 1 to the anhydride derivative 3 or the dicarboxylic acid derivative 4 is stepwise and the intermediates 2a and 2b formed by initial hydrolytic attack have been observed under alkaline conditions. An overall mechanism for the hydrolysis of 1 in aqueous solution has been proposed. Extrapolating Arrhenius behavior to the hydrolysis reaction of 1 in aqueous solution maintained at a pH value of 4 suggests an aqueous buffered formulation has sufficient thermal stability to be considered a robust room temperature drug product. PMID:20025967

Breslin, David; Sato, Yuichi; Karki, Shyam B

2009-12-16

66

Homogeneous hydrolysis rate constants for selected chlorinated methanes, ethanes, ethenes, and propanes  

Microsoft Academic Search

Hydrolysis rate constants of 18 chlorinated methanes, ethanes, ethenes, and propanes were measured in dilute aqueous solutions within the temperature range of 0 to 180 C and at pH values of 3 to 14. Arrhenius parameters were determined for both neutral and alkaline hydrolysis reactions. Reactivity of these compounds in basic solutions increases in accord with the expected acidity of

Peter M. Jeffers; Lisa M. Ward; Lisa M. Woytowitch; N. Lee Wolfe

1989-01-01

67

Enzymatic hydrolysis and glucose fermentation of wet oxidized sugarcane bagasse and rice straw for bioethanol production  

Microsoft Academic Search

Alkaline wet oxidation was used as pretreatment method of sugarcane bagasse (SB) and rice straw (RS) prior to enzymatic hydrolysis and glucose fermentations with Saccharomyces cerevisiae. At high enzyme loadings, the enzymatic hydrolysis of wet oxidized sugarcane bagasse (SBWO) resulted in the highest degree of saccharification compared to wet oxidized rice straw (RSWO). However, at enzyme concentrations below 10 FPU\\/g-cellulose,

68

Towards zero discharge of chromium-containing leather waste through improved alkali hydrolysis  

Microsoft Academic Search

The treatment of chromium-containing leather waste (CCLW), the major solid waste generated at the post-tanning operations of leather processing, has the potential to generate value-added leather chemicals. Various alkali and enzymatic hydrolysis were compared, and calcium oxide was found to be important for effective (but still incomplete) hydrolysis. Three possible reasons are given for the incomplete hydrolysis under alkaline conditions.

Changdao Mu; Wei Lin; Mingrang Zhang; Qingshi Zhu

2003-01-01

69

Sugarcane bagasse mild alkaline/oxidative pretreatment for ethanol production by alkaline recycle process.  

PubMed

In order to decrease the alkali and water consumptions in the sugarcane bagasse alkaline/oxidative pretreatment for ethanol production, an alkaline recycle process was carried out. Two recycles of NaOH/H2O2 pretreatment did not decrease the pretreatment and enzymatic hydrolysis efficiencies and the consumptions of NaOH and water would be saved by 26% and 40%, respectively. A simultaneous saccharification and fermentation (SSF) culture with pretreated bagasse as substrate was developed giving 25 g ethanol l(-1) with a yield of 0.2 g g(-1) bagasse and productivity of 0.52 g l(-1) h(-1). PMID:18327542

Cheng, Ke-Ke; Zhang, Jian-An; Ping, Wen-Xiang; Ge, Jing-Ping; Zhou, Yu-Jie; Ling, Hong-Zhi; Xu, Jing-Ming

2008-03-08

70

Production of Electrical Energy from Carbohydrates using a Transition Metal-Catalysed Liquid Alkaline Fuel Cell  

Microsoft Academic Search

Biomass may be converted to energy by enzymatic hydrolysis to monomer components and fermentative conversion of those products to ethanol for use as fuel. Both glucose and xylose in aqueous solution were directly converted to electrical energy using a liquid alkaline fuel cell (AFC) at room temperature. Hydrolysis products derived from the action of cellulase and amylase on cellulose and

J. McGinley; F. N. McHale; P. Hughes; C. N. Reid; A. P. McHale

2004-01-01

71

Waste activated sludge hydrolysis and short-chain fatty acids accumulation under mesophilic and thermophilic conditions: Effect of pH  

Microsoft Academic Search

The effect of pH (4.0–11.0) on waste activated sludge (WAS) hydrolysis and short-chain fatty acids (SCFAs) accumulation under mesophilic and thermophilic conditions were investigated. The WAS hydrolysis increased markedly in thermophilic fermentation compared to mesophilic fermentation at any pH investigated. The hydrolysis at alkaline pHs (8.0–11.0) was greater than that at acidic pHs, but both of the acidic and alkaline

Peng Zhang; Yinguang Chen; Qi Zhou

2009-01-01

72

Study on the hydrolysis of 2-chlorobenzamide.  

PubMed

It is reported that 2-chlorobenzamide, one of the chief degradation products of CCU (1-(2-chlorobenzoyl)-3-(4-chlorophenyl) urea), a new insect growth regulator, is a potential carcinogen, but few studies about its environmental stability have been found. This paper is concerned with the hydrolysis of 2-chlorobenzamide as part of the environmental study of CCU. The results showed that 2-chlorobenzamide is relatively stable in solutions of pH = 6 and 8, for which the rate constants are 0.00286 h(-)(1) (R = 99.13%, SD = 0. 0095) and 0.00109 h(-)(1) (R = 96.70%, SD = 0.0072), respectively. Hydrolysis was more rapid in acidic (pH = 5), alkaline (pH = 10), and neutral (pH = 7) environments, with hydrolytic rate constants of 0.00417h(-)(1) (R = 95.76%, SD = 0.0390), 0.00411h(-)(1) (R = 99.89%, SD = 0.0162) and 0.00408h(-)(1) (R = 98.29%, SD = 0.0237), respectively. The change of the rate of hydrolysis with pH showed two minima at 25 degrees C. Temperature has some impact on the hydrolysis, showing at higher temperature the larger rate of reaction. PMID:10888586

Qingxiang, Z; Wenying, L; Guoguang, L; Xiuling, X

2000-06-01

73

New Approaches in Modeling Carbonate Alkalinity and Total Alkalinity  

Microsoft Academic Search

Alkaline measurements (carbonate alkalinity and total alkalinity) are of great importance in analyses of ocean, marine, lake and river waters, and other samples. Carbonate alkalinity (CA) refers to the cases in which only bicarbonate and carbonate species are considered. Total alkalinity (Alk) implies additional species having acid-base properties. Biochemical processes give rise to the organic alkalinity (OA) in natural waters.

Tadeusz Micha?owski; Agustin G. Asuero

2012-01-01

74

Progressing batch hydrolysis process  

DOEpatents

A progressive batch hydrolysis process is disclosed for producing sugar from a lignocellulosic feedstock. It comprises passing a stream of dilute acid serially through a plurality of percolation hydrolysis reactors charged with feed stock, at a flow rate, temperature and pressure sufficient to substantially convert all the cellulose component of the feed stock to glucose. The cooled dilute acid stream containing glucose, after exiting the last percolation hydrolysis reactor, serially fed through a plurality of pre-hydrolysis percolation reactors, charged with said feedstock, at a flow rate, temperature and pressure sufficient to substantially convert all the hemicellulose component of said feedstock to glucose. The dilute acid stream containing glucose is cooled after it exits the last prehydrolysis reactor.

Wright, J.D.

1985-01-10

75

Reaction pathways and free energy profiles for spontaneous hydrolysis of urea and tetramethylurea: unexpected substituent effects.  

PubMed

It has been difficult to directly measure the spontaneous hydrolysis rate of urea and, thus, 1,1,3,3-tetramethylurea (Me4U) was used as a model to determine the "experimental" rate constant for urea hydrolysis. The use of Me4U was based on an assumption that the rate of urea hydrolysis should be 2.8 times that of Me4U hydrolysis because the rate of acetamide hydrolysis is 2.8 times that of N,N-dimethyl-acetamide hydrolysis. The present first-principles electronic-structure calculations on the competing non-enzymatic hydrolysis pathways have demonstrated that the dominant pathway is the neutral hydrolysis via the CN addition for both urea (when pH < ?11.6) and Me4U (regardless of pH), unlike the non-enzymatic hydrolysis of amides where alkaline hydrolysis is dominant. Based on the computational data, the substituent shift of the free energy barrier calculated for the neutral hydrolysis is remarkably different from that for the alkaline hydrolysis, and the rate constant for the urea hydrolysis should be ?1.3 × 10(9)-fold lower than that (4.2 × 10(-12) s(-1)) measured for the Me4U hydrolysis. As a result, the rate enhancement and catalytic proficiency of urease should be 1.2 × 10(25) and 3 × 10(27) M(-1), respectively, suggesting that urease surpasses proteases and all other enzymes in its power to enhance the rate of reaction. All of the computational results are consistent with available experimental data for Me4U, suggesting that the computational prediction for urea is reliable. PMID:24097048

Yao, Min; Tu, Wenlong; Chen, Xi; Zhan, Chang-Guo

2013-10-16

76

Enzymatic hydrolysis of molasses  

Microsoft Academic Search

Kinetic studies of the enzymatic hydrolysis of molasses were conducted using glucoamylase. Central Sugar Refinery SDN BHD contains 13–20% glucose. The molasses was diluted and the kinetic experiments were conducted at 67 °C with 100–1000 mg\\/l of glucoamylase. The glucose contents of the molasses were enhanced after hydrolysis of molasses solution with 1000 mg\\/l glucoamylase. A Lineweaver–Burk plot was obtained

Ghasem D. Najafpour; Cheong Poi Shan

2003-01-01

77

Contribution of hydrolysis in the abiotic attenuation of RDX and HMX in coastal waters.  

PubMed

Sinking of military ships, dumping of munitions during the two World Wars, and military training have resulted in the undersea deposition of numerous unexploded ordnances (UXOs). Leaching of energetic compounds such as hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) and octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) from these UXOs may cause adverse ecological effects so that the long-term fate of these chemicals in the sea should be known. The present study assesses the contribution of alkaline hydrolysis into the natural attenuation of RDX and HMX in coastal waters. Alkaline hydrolysis rates were shown to be unaffected by the presence of sodium chloride, the most common component in marine waters. Kinetic parameters (E(a), ln A, k(2)) quantified for the alkaline hydrolysis of RDX and HMX in deionized water (30-50 degrees C, pH 10-12) agreed relatively well with abiotic degradation rates determined in sterilized natural coastal waters (50 and 60 degrees C, variable salinity) even if the latter were generally slightly faster than the former. Furthermore, similar products (HCHO, NO(2)(-), O(2)NNHCH(2)NHCHO) were obtained on alkaline hydrolysis in deionized water and abiotic degradation in coastal waters. These two findings suggested that degradation of nitramines in sterilized natural coastal waters, away from light, was mainly governed by alkaline hydrolysis. Kinetic calculations using the present parameters showed that alkaline hydrolysis of RDX and HMX in marine waters at 10 degrees C would respectively take 112 +/- 10 and 2408 +/- 217 yr to be completed (99.0%). We concluded that under natural conditions hydrolysis should not contribute significantly to the natural attenuation of HMX in coastal waters whereas it could play an active role in the natural attenuation of RDX. PMID:18453407

Monteil-Rivera, Fanny; Paquet, Louise; Giroux, Romain; Hawari, Jalal

2008-05-02

78

Comparative study on chemical pretreatments to accelerate enzymatic hydrolysis of aquatic macrophyte biomass used in water purification processes  

Microsoft Academic Search

In this study, enzymatic hydrolysis of two floating aquatic plants which are suitable for water purification, water hyacinth (Eichhornia crassipes) and water lettuce (Pistia stratiotes L.), was performed to produce sugars. Twenty chemical pretreatments were comparatively examined in order to improve the efficiency of enzymatic hydrolysis. As a result, the alkaline\\/oxidative (A\\/O) pretreatment, in which sodium hydroxide and hydrogen peroxide

D. Mishima; M. Tateda; M. Ike; M. Fujita

2006-01-01

79

Alkaline "Permanent" Paper.  

ERIC Educational Resources Information Center

Discussion of paper manufacturing processes and their effects on library materials focuses on the promotion of alkaline "permanent" paper, with less acid, by Canadian library preservation specialists. Standards for paper acidity are explained; advantages of alkaline paper are described, including decreased manufacturing costs; and recyclability is…

Pacey, Antony

1991-01-01

80

Anodes for alkaline electrolysis  

DOEpatents

A method of making an anode for alkaline electrolysis cells includes adsorption of precursor material on a carbonaceous material, conversion of the precursor material to hydroxide form and conversion of precursor material from hydroxide form to oxy-hydroxide form within the alkaline electrolysis cell.

Soloveichik, Grigorii Lev (Latham, NY)

2011-02-01

81

Alkaline "Permanent" Paper.  

ERIC Educational Resources Information Center

|Discussion of paper manufacturing processes and their effects on library materials focuses on the promotion of alkaline "permanent" paper, with less acid, by Canadian library preservation specialists. Standards for paper acidity are explained; advantages of alkaline paper are described, including decreased manufacturing costs; and recyclability…

Pacey, Antony

1991-01-01

82

Alkaline igneous rocks  

SciTech Connect

In this volume, an international team of scientists provides an up-to-date overview of the nature, origin, and evolution of alkaline magmas. Particular attention is paid to carbonatites, lamprophyres, and lamproites which are rock suites of current interest not recently reviewed elsewhere. Recent work on the classical alkaline provinces of East Africa, South Greenland, and the Kola Peninsula is included together with reviews of other areas of alkaline magmatism in North and South America, East Greenland, Europe, West Africa, and the ocean basins. Other papers discuss the impact of experimental isotopic and geochemical studies of the petrogenesis of alkaline rocks. This book will be of interest to petrologists and geochemists studying alkaline igneous rocks, and to other earth scientists as a reference on the rapidly expanding field of igneous petrology.

Fitton, J.G.; Upton, B.G.J. (eds.)

1987-01-01

83

The effect of acrylic comonomers on the hydrolytic stability of polyacrylamides at high temperature in alkaline solution  

SciTech Connect

A major cause of instability in acrylamide-based polymers used in tertiary oil recovery is hydrolysis of the amide groups, especially at alkaline pH and high temperatures. Changes in polymer composition resulting from hydrolysis can cause precipitation from sea-water solutions. This work has studied the effects of the sodium salts of acrylic acid and acrylamidomethyl propane sulfonic acid (AMPS) on the rate of hydrolysis of acrylamide copolymers in alkaline solutions at high temperatures. Copolymers were prepared containing 0 - 50% of the anionic comonomers and hydrolyzed in aqueous solution at pH 8.5 at 90/sup 0/, 107/sup 0/, and 120/sup 0/C. The extent of hydrolysis was measured by a conductimetric method, analyzing for the total carboxylate content. It was found that the rate of hydrolysis decreased as the mole ratio of either of the anionic comonomers increased and that AMPS was more effective in preventing hydrolysis at all of the temperatures studied.

Dexter, R.W.; Ryles, R.G.

1988-05-01

84

Hydrolysis of CL-20.  

National Technical Information Service (NTIS)

The Energetics and Warheads Division of the U.S. Army Armament Research, Development and Engineering Center has been involved in the development of CL-20. An aqueous hydrolysis study was performed to better understand the fate and transport of CL-20 throu...

J. Pavlov M. Sidhoum C. Christodoulatos W. Balas S. Nicolich

2005-01-01

85

Ester hydrolysis rate constant prediction from infrared interferograms  

Microsoft Academic Search

A method for predicting reactivity parameters of organic chemicals from spectroscopic data is being developed to assist in assessing the environmental fate of pollutants. The prototype system, which employs multiple linear regression analysis using selected points from the Fourier transforms of mid-infrared gas-phase spectra, has been applied to the prediction of the alkaline hydrolysis rate constants (k{sub OH}) of 41

Timothy W. Collette

1990-01-01

86

Uranium in alkaline rocks  

SciTech Connect

Geologic and geochemical criteria were developed for the occurrence of economic uranium deposits in alkaline igneous rocks. A literature search, a limited chemical analytical program, and visits to three prominent alkaline-rock localities (Ilimaussaq, Greenland; Pocos de Caldas, Brazil; and Powderhorn, Colorado) were made to establish criteria to determine if a site had some uranium resource potential. From the literature, four alkaline-intrusive occurrences of differing character were identified as type-localities for uranium mineralization, and the important aspects of these localities were described. These characteristics were used to categorize and evaluate U.S. occurrences. The literature search disclosed 69 U.S. sites, encompassing nepheline syenite, alkaline granite, and carbonatite. It was possible to compare two-thirds of these sites to the type localities. A ranking system identified ten of the sites as most likely to have uranium resource potential.

Murphy, M.; Wollenberg, H.; Strisower, B.; Bowman, H.; Flexser, S.; Carmichael, I.

1978-04-01

87

DFT investigations of phosphotriesters hydrolysis in aqueous solution: a model for DNA single strand scission induced by N-nitrosoureas.  

PubMed

DNA phosphotriester adducts are common alkylation products of DNA phosphodiester moiety induced by N-nitrosoureas. The 2-hydroxyethyl phosphotriester was reported to hydrolyze more rapidly than other alkyl phosphotriesters both in neutral and in alkaline conditions, which can cause DNA single strand scission. In this work, DFT calculations have been employed to map out the four lowest activation free-energy profiles for neutral and alkaline hydrolysis of triethyl phosphate (TEP) and diethyl 2-hydroxyethyl phosphate (DEHEP). All the hydrolysis pathways were illuminated to be stepwise involving an acyclic or cyclic phosphorane intermediate for TEP or DEHEP, respectively. The rate-limiting step for all the hydrolysis reactions was found to be the formation of phosphorane intermediate, with the exception of DEHEP hydrolysis in alkaline conditions that the decomposition process turned out to be the rate-limiting step, owing to the extraordinary low formation barrier of cyclic phosphorane intermediate catalyzed by hydroxide. The rate-limiting barriers obtained for the four reactions are all consistent with the available experimental information concerning the corresponding hydrolysis reactions of phosphotriesters. Our calculations performed on the phosphate triesters hydrolysis predict that the lower formation barriers of cyclic phosphorane intermediates compared to its acyclic counter-part should be the dominant factor governing the hydrolysis rate enhancement of DEHEP relative to TEP both in neutral and in alkaline conditions. PMID:23001331

Liu, Tingting; Zhao, Lijiao; Zhong, Rugang

2012-09-22

88

Hydrogen production from catalytic hydrolysis of sodium borohydride solution using nickel boride catalyst  

Microsoft Academic Search

A highly stable and active nickel boride catalyst (NixB) was prepared and tested for the catalytic hydrolysis of alkaline NaBH4 solution. It was found that after heat treatment at 150°C in vacuum the NixB catalyst shows greatly enhanced catalytic activity and operational stability. In the experimental conditions, the hydrolysis reaction can produce 6.75wt% hydrogen at 45°C and >4.0wt% hydrogen even

Dong Hua; Yang Hanxi; Ai Xinping; Cha Chuansin

2003-01-01

89

Potentiometric determination of the ‘formal’ hydrolysis ratio of aluminium species in aqueous solutions  

Microsoft Academic Search

The ‘formal’ hydrolysis ratio (h=C(OH?)added\\/C(Al)total) of hydrolysed aluminium-ions is an important parameter required for the exhaustive and quantitative speciation–fractionation of aluminium in aqueous solutions. This paper describes a potentiometric method for determination of the formal hydrolysis ratio based on an automated alkaline titration procedure. The method uses the point of precipitation of aluminium hydroxide as a reference (h=3.0) in order

Agathe C. Fournier; Kirill L. Shafran; Carole C. Perry

2008-01-01

90

Effect of metal ions on the activity of green crab ( Scylla serrata) alkaline phosphatase  

Microsoft Academic Search

Green crab (Scylla serrata) alkaline phosphatase (EC 3.1.3.1) is a metalloenzyme, which catalyzes the nonspecific hydrolysis of phosphate monoesters. The present paper deals with the study of the effect of some kinds of metal ions on the enzyme. The positive monovalent alkali metal ions (Li+, Na+ and K+) have no effect on the enzyme; positive bivalent alkaline-earth metal ions (Mg2+,

Qing-Xi Chen; Wen-Zhu Zheng; Jing-Yu Lin; Yan Shi; Wen-Zhang Xie; Hai-Meng Zhou

2000-01-01

91

Alkaline phosphatase activity in subtropical Central North Pacific waters using a sensitive fluorometric method  

Microsoft Academic Search

This paper describes a fluorometric method for assaying low levels of the enzyme alkaline phosphatase in seawater. The assay is based on the hydrolysis of the monophosphate ester bond of 3-0-methylfluorescein phosphate. This enzyme is synthesized by many microorganisms when phosphate becomes limiting. Alkaline phosphatase activity was detected in phytoplankton from the nutrient-impoverished surface waters of the subtropical Central North

M. J. Perry

1972-01-01

92

Rechargeable Alkaline Zinc System.  

National Technical Information Service (NTIS)

Rechargeable alkaline zinc batteries have been investigated heretofore as power sources capable of high energy density applications. One of the major problems with their use is the short circuiting of the unit cells by growth of zinc dendrites from the an...

O. C. Wagner

1970-01-01

93

Alkaline Galvanic Cell.  

National Technical Information Service (NTIS)

The invention covers an alkaline galvanic cell of cylindrical shape, having an outer positive electrode, a hollow negative electrode within the former and separated from it by an ion-conductive separator wall, said negative electrode being made of zinc pa...

F. K. Nabuillin I. I. Koval L. F. Penkova N. S. Lidorenko Z. M. Busova

1973-01-01

94

Secondary alkaline batteries  

SciTech Connect

This report on secondary alkaline batteries covers the overall reactions (charge/discharge characteristics), electrode structures and materials, and cell construction. The following batteries are studied, nickel oxide-cadmium, nickel oxide-iron, nickel oxide-hydrogen, nickel oxide-zinc, silver oxide-zinc, and silver oxide-cadmium, silver oxide-iron, and manganese dioxide-zinc batteries.

McBreen, J.

1984-03-01

95

HOMOGENEOUS HYDROLYSIS RATE CONSTANTS FOR SELECTED CHLORINATED METHANES, ETHANES, ETHENES, AND PROPANES  

EPA Science Inventory

Hydrolysis rate constants of 18 chlorinated methanes, ethanes, ethenes, and propanes have been measured in dilute aqueous solutions within the temperature range of 0 to 180 oC and at pH values of 3 to l4. rrhenius parapmeters were determined for both neutral and alkaline hydrolys...

96

Enzymatic hydrolysis of chemithermomechanically pretreated sugarcane bagasse and samples with reduced initial lignin content.  

PubMed

Chemithermomechanical (CTM) processing was used to pretreat sugarcane bagasse with the aim of increasing cell wall accessibility to hydrolytic enzymes. Yields of the pretreated samples were in the range of 75-94%. Disk refining and alkaline-CTM and alkaline/sulfite-CTM pretreatments yielded pretreated materials with 21.7, 17.8, and 15.3% of lignin, respectively. Hemicellulose content was also decreased to some extent. Fibers of the pretreated materials presented some external fibrillation, fiber curling, increased swelling, and high water retention capacity. Cellulose conversion of the alkaline-CTM- and alkaline/sulfite-CTM-pretreated samples reached 50 and 85%, respectively, after 96 h of enzymatic hydrolysis. Two samples with low initial lignin content were also evaluated after the mildest alkaline-CTM pretreatment. One sample was a partially delignified mill-processed bagasse. The other was a sugarcane hybrid selected in a breeding program. Samples with lower initial lignin content were hydrolyzed considerably faster in the first 24 h of enzymatic digestion. For example, enzymatic hydrolysis of the sample with the lowest initial lignin content (14.2%) reached 64% cellulose conversion after only 24 h of hydrolysis when compared with the 30% observed for the mill-processed bagasse containing an initial lignin content of 24.4%. PMID:21344677

Mendes, Fernanda M; Siqueira, Germano; Carvalho, Walter; Ferraz, André; Milagres, Adriane M F

2011-02-22

97

Catalytic hydrolysis of carbonyl sulfide  

SciTech Connect

Hydrolysis of COS in gas streams to H/sub 2/S and CO/sub 2/ can be improved by using certain bicyclo tertiary amine catalysts. Bicyclo tertiary amine catalysts can enhance COS hydrolysis in an acid gas removal solvent in the liquid phase or on a solid support system in the gas phase.

Chen, M. S.; Edwards, T. J.; Ernst, W. R.

1985-06-18

98

[Impact of liquid volume of recycled methanogenic effluent on anaerobic hydrolysis].  

PubMed

Methanogenic effluent was recycled to regulate hydrolysis during two-phase anaerobic digestion of organic solid wastes. In order to study the impact of recycled effluent's volume on hydrolysis, four hydrolysis reactors filled with vegetable and flower wastes were constructed, with different liquid volumes of recycled methanogenic effluent, i.e., 0.1, 0.5, 1.0, 2.0 m3/(m3 x d), respectively. The parameters related to hydrolytic environment (pH, alkalinity, ORP, concentrations of ammonia and reducing sugar), microbial biomass and hydrolysis efficiency (accumulated SCOD, accumulated reducing sugar, and hydrolysis rate constants) were monitored. This research shows that recycling methanogenic effluent into the hydrolysis reactor can enhance its buffer capability and operation stability; higher recycled volume is favorable for microbial anabolism and further promotes hydrolysis. After 9 days of reaction, the accumulated SCOD in the hydrolytic effluent reach 334, 407, 413, 581 mg/g at recycled volumes of 0.1, 0.5, 1.0, 2.0 m3/(m3 x d) and their first-order hydrolysis rate kinetic constants are 0.065, 0.083, 0.089, 0.105 d(-1), respectively. PMID:19068657

Hao, Li-ping; Lü, Fan; He, Pin-jing; Shao, Li-ming

2008-09-01

99

Promiscuous Sulfatase Activity and Thio-Effects in a Phosphodiesterase of the Alkaline Phosphatase Superfamily †  

Microsoft Academic Search

The nucleotide phosphodiesterase\\/pyrophosphatase from Xanthomonas axonopodis (NPP) is a structural and evolutionary relative of alkaline phosphatase that preferentially hydrolyzes phosphate diesters. With the goal of understanding how these two enzymes with nearly identical Zn2+ bimetallo sites achieve high selectivity for hydrolysis of either phosphate monoesters or diesters, we have measured a promiscuous sulfatase activity in NPP. Sulfate esters are nearly

Jonathan K. Lassila; Daniel Herschlag

2008-01-01

100

Effects of Oxodiperoxovanadate (V) Complexes on the Activity of Green Crab (Scylla serrata) Alkaline Phosphatase  

Microsoft Academic Search

Green crab (Scylla serrata) alkaline phosphatase (EC 3.1.3.1) is a metalloenzyme that catalyzes the nonspecific hydrolysis of phosphate monoesters. The effects of some pollutants in seawater on the activity of the enzyme will result in the loss of the biological function of the enzyme, which will affect the exuviating crab shell and threaten the survival of the animal. In the

X.-W. Zhou; Q.-X. Chen; Z. Chen; Z.-Q. He; H.-M. Zhou

2000-01-01

101

Improved absorption of caseinophosphopeptide-bound iron: role of alkaline phosphatase  

Microsoft Academic Search

Hydrolysis of proteins could lessen their inhibiting effect on the poor absorption of cow's milk iron (Fe), which is responsible for the high incidence of Fe deficiency worldwide. When bound to Fe, caseinophosphopeptides (CPP) derived from milk proteins resist luminal digestion, enhance Fe solubility and could improve its bioavailability; brush border enzyme alkaline phosphatase activity could influence iron absorption by

Bertille Ani-Kibangou; Saïd Bouhallab; Daniel Mollé; Gwénaële Henry; François Bureau; Dominique Neuville; Pierre Arhan; Dominique Bouglé

2005-01-01

102

Hydrolysis reactor for hydrogen production  

DOEpatents

In accordance with certain embodiments of the present disclosure, a method for hydrolysis of a chemical hydride is provided. The method includes adding a chemical hydride to a reaction chamber and exposing the chemical hydride in the reaction chamber to a temperature of at least about 100.degree. C. in the presence of water and in the absence of an acid or a heterogeneous catalyst, wherein the chemical hydride undergoes hydrolysis to form hydrogen gas and a byproduct material.

Davis, Thomas A.; Matthews, Michael A.

2012-12-04

103

Enzymatic fat hydrolysis and synthesis  

Microsoft Academic Search

The hydrolysis of tallow, coconut oil and olive oil, by lipase fromCandida rugosa, was studied. The reaction approximates a firstorder kinetics model. Its rate is unaffected by temperature in the range of\\u000a 26–46 C. Olive oil is more rapidly hydrolyzed compared to tallow and coconut oil. Hydrolysis is adversely affected by hydrocarbon\\u000a solvents and a nonionic surfactant. Since amounts of

Warner M. Linfield; Robert A. Barauskas; Lorraine Sivieri; Samuel Serota; Robert W. Stevenson

1984-01-01

104

Evaluation of High Solids Alkaline Pretreatment of Rice Straw  

PubMed Central

Fresh-harvested, air-dried rice straw was pretreated at a water content of 5 g H2O/g straw using sodium hydroxide (NaOH) and compared to pretreatment at 10 g H2O/g straw by hydrated lime (Ca(OH)2). Full factorial experiments including parallel wash-only treatments were completed with both sources of alkali. The experiments were designed to measure the effects of alkaline loading and pretreatment time on delignification and sugar yield upon enzymatic hydrolysis. Reaction temperature was held constant at 95°C for lime pretreatment and 55°C for NaOH pretreatment. The range of delignification was 13.1% to 27.0% for lime pretreatments and was 8.6% to 23.1% for NaOH pretreatments. Both alkaline loading and reaction time had significant positive effects (p?alkaline loading had a significant positive effect on enzymatic hydrolysis. Treatment at higher temperature also improved delignification; delignification with water alone ranged from 9.9% to 14.5% for pretreatment at 95°C, but there was little effect observed at 55°C. Post-pretreatment washing of biomass was not necessary for subsequent enzymatic hydrolysis. Maximum glucose yields were 176.3 mg/g dried biomass (48.5% conversion efficiency of total glucose) in lime-pretreated and unwashed biomass and were 142.3 mg/g dried biomass (39.2% conversion efficiency of total glucose) in NaOH-pretreated and unwashed biomass.

Cheng, Yu-Shen; Zheng, Yi; Yu, Chao Wei; Dooley, Todd M.; Jenkins, Bryan M.

2010-01-01

105

Evaluation of high solids alkaline pretreatment of rice straw.  

PubMed

Fresh-harvested, air-dried rice straw was pretreated at a water content of 5 g H(2)O/g straw using sodium hydroxide (NaOH) and compared to pretreatment at 10 g H(2)O/g straw by hydrated lime (Ca(OH)(2)). Full factorial experiments including parallel wash-only treatments were completed with both sources of alkali. The experiments were designed to measure the effects of alkaline loading and pretreatment time on delignification and sugar yield upon enzymatic hydrolysis. Reaction temperature was held constant at 95 degrees C for lime pretreatment and 55 degrees C for NaOH pretreatment. The range of delignification was 13.1% to 27.0% for lime pretreatments and was 8.6% to 23.1% for NaOH pretreatments. Both alkaline loading and reaction time had significant positive effects (p < 0.001) on delignification under the design conditions, but only alkaline loading had a significant positive effect on enzymatic hydrolysis. Treatment at higher temperature also improved delignification; delignification with water alone ranged from 9.9% to 14.5% for pretreatment at 95 degrees C, but there was little effect observed at 55 degrees C. Post-pretreatment washing of biomass was not necessary for subsequent enzymatic hydrolysis. Maximum glucose yields were 176.3 mg/g dried biomass (48.5% conversion efficiency of total glucose) in lime-pretreated and unwashed biomass and were 142.3 mg/g dried biomass (39.2% conversion efficiency of total glucose) in NaOH-pretreated and unwashed biomass. PMID:20440580

Cheng, Yu-Shen; Zheng, Yi; Yu, Chao Wei; Dooley, Todd M; Jenkins, Bryan M; VanderGheynst, Jean S

2010-05-04

106

High performance liquid chromatographic determination of etofibrate and its hydrolysis products.  

PubMed

High performance liquid chromatographic (HPLC) method is presented for the determination of etofibrate (EF) and its hydrolysis products. The method was based on HPLC separation of EF from its hydrolysis products using cyanopropyl column at ambient temperature with mobile phase consisting of acetonitrile-10 mM potassium dihydrogen phosphate, pH was adjusted to 4.1 using phosphoric acid (50:50, v/v). Quantitation was achieved with UV detection at 221 nm based on peak area. The flow rate was 1.5 ml min(-1). The proposed method was used to investigate the kinetics of acidic hydrolysis process of EF at different temperatures and the apparent pseudo first-order rate constant, half-life and activation energy were calculated. The kinetics of alkaline hydrolysis process of EF using 0.01 M sodium hydroxide at different temperatures cannot be studied as the drug is rapidly hydrolyzed in alkaline medium. The pH-rate profile of hydrolysis of EF in Britton-Robinson buffer solutions within the pH range 2-10 were studied. PMID:16901673

el-Gindy, Alaa; Hadad, Ghada M; Mahmoud, Waleed M M

2006-08-09

107

Salt Effects on an Ion–Molecule Reaction—Hydroxide-Catalyzed Hydrolysis of Benzocaine  

Microsoft Academic Search

\\u000a Purpose  This work investigates the effect of various salts on the rate of a reaction involving a neutral species (benzocaine alkaline\\u000a hydrolysis).\\u000a \\u000a \\u000a \\u000a Methods  Benzocaine hydrolysis kinetics in NaOH solutions in the presence of different salts were studied at 25C. Benzocaine solubility\\u000a in salt solutions was also determined. Solubility data were used to estimate salt effects on benzocaine activity coefficients,\\u000a and pH was

Ahmad Al-Maaieh; Douglas R. Flanagan

2006-01-01

108

Role of Drosophila alkaline ceramidase (Dacer) in Drosophila development and longevity.  

PubMed

Ceramidases catalyze the hydrolysis of ceramides to generate sphingosine (SPH) and fatty acids, and ceramide metabolism is implicated in various biological responses in Drosophila melanogaster. Here we report the cloning, biochemical characterization, and functional analysis of a Drosophila alkaline ceramidase (Dacer). Dacer, a membrane-bound protein of 284 amino acids, shares homology with yeast and mammalian alkaline ceramidases. Overexpression of Dacer in High Five insect cells increases ceramidase activity in the alkaline pH range, indicating that Dacer is a bona fide alkaline ceramidase. Dacer mRNA is highly expressed in the midgut and at the pupal stage. An inactivation of Dacer by insertional mutagenesis increases the levels of ceramides in both Drosophila pupae and adult flies. Dacer inactivation increases Drosophila pre-adult development time, lifespan, and anti-oxidative stress capacity. Collectively, these results suggest that Dacer plays an important role in the Drosophila development and longevity by controlling the metabolism of ceramides. PMID:20112046

Yang, Qiong; Gong, Zhong-Jun; Zhou, Ying; Yuan, Jing-Qun; Cheng, Jiaan; Tian, Lin; Li, Sheng; Lin, Xin-Da; Xu, Ruijuan; Zhu, Zeng-Rong; Mao, Cungui

2010-01-30

109

Investigating lignin and hemicellulose in white rot fungus-pretreated wood that affect enzymatic hydrolysis.  

PubMed

Selective delignification and hemicellulose removal were performed on white rot fungus-pretreated residues to investigate the effects of lignin and hemicellulose removal on enzymatic hydrolysis. 43.66-77% of lignin with small part of hemicellulose were degraded by chlorite treatment, while 79.97-95.09% of hemicellulose with little lignin were degraded by dilute acid treatment, indicating that cross effect between lignin and hemicellulose was minimized. In subsequent enzymatic digestion, regardless of the cellulase loading, residues from series-grade delignification released more glucose and xylose than that from hemicellulose removal, suggesting that lignin rather than hemicellulose in fungi-pretreated residues played a dominant role in hindering enzymatic hydrolysis. Based on the fundamental mechanisms of acidic/alkaline pretreatments in literature, it is proposed that fungal pretreatment prefers to integrate with alkaline pretreatment rather than acidic pretreatment to maximize the synergy. This indication would be helpful to optimize and renovate the integrated pretreatment. PMID:23489565

Wang, Wei; Yuan, Tongqi; Cui, Baokai; Dai, Yucheng

2013-02-21

110

Catalytic hydrolysis of sodium borohydride by a novel nickel–cobalt–boride catalyst  

Microsoft Academic Search

With the aim of designing an efficient hydrogen generator for portable fuel cell applications nickel–cobalt–boride (Ni–Co–B) catalysts were prepared by a chemical reduction method and their catalytic hydrolysis reaction with alkaline NaBH4 solution was studied. The performance of the catalysts prepared from NaBH4 solution with NaOH, and without NaOH show different hydrogen generation kinetics. The rate of hydrogen generation was

J. C. Ingersoll; N. Mani; J. C. Thenmozhiyal; A. Muthaiah

2007-01-01

111

Hydrogen generation and storage from hydrolysis of sodium borohydride in batch reactors  

Microsoft Academic Search

The catalytic hydrolysis of alkaline sodium borohydride (NaBH4) solution was studied using a non-noble; nickel-based powered catalyst exhibiting strong activity even after long time storage. This easy-to-prepare catalyst showed an enhanced activity after being recovered from previous use. The effects of temperature, NaBH4 concentration, NaOH concentration and pressure on the hydrogen generation rate were investigated. Particular importance has the effect

A. M. F. R. Pinto; D. S. Falcão; R. A. Silva; C. M. Rangel

2006-01-01

112

Alkaline Phosphatase Assay for Freshwater Sediments: Application to Perturbed Sediment Systems  

PubMed Central

The p-nitrophenyl phosphate hydrolysis-phosphatase assay was modified for use in freshwater sediment. Laboratory studies indicated that the recovery of purified alkaline phosphatase activity was 100% efficient in sterile freshwater sediments when optimized incubation and sonication conditions were used. Field studies of diverse freshwater sediments demonstrated the potential use of this assay for determining stream perturbation. Significant correlations between phosphatase and total viable cell counts, as well as adenosine triphosphate biomass, suggested that alkaline phosphatase activity has utility as an indicator of microbial population density and biomass in freshwater sediments.

Sayler, Gary S.; Puziss, Marla; Silver, Martin

1979-01-01

113

Hydrolysis of Dibromo fluoromethyl triphenylpho sphonium Bromide.  

National Technical Information Service (NTIS)

Hydrolysis of (Ph3PCFBr2)Br(-) afforded a high yield of dibromofluoromethane and triphenylphosphine oxide. Hydrolysis in the presence of a radioactive isotope of bromine gave evidence that the mechanism of this reaction proceeds via the dibromofluoromethi...

D. J. Burton R. M. Flynn R. G. Manning R. M. Kessler

1982-01-01

114

Alkaline detergent recycling via ultrafiltration.  

National Technical Information Service (NTIS)

The metal finishing industry uses alkaline cleaners and detergents to remove oils and dirt from manufactured parts, often before they are painted or plated. The use of these cleaners has grown because environmental regulations are phasing out ozone deplet...

C. Steffani M. Meltzer

1995-01-01

115

?-Amylase inactivation during corn starch hydrolysis process  

Microsoft Academic Search

The effects of operating conditions on the enzymatic hydrolysis of corn starch were investigated. A commercial ?-amylase produced by Bacillus sp. was used for the hydrolysis experiments. The degree of starch hydrolysis (%) and residual ?-amylase activity (%) was investigated versus process variables, including pH, temperature, viscosity, impeller speed, processing time and some materials added such as hydrolysate, maltose, glucose,

Dilek K?l?ç Apar; Belma Özbek

2004-01-01

116

?-Amylase inactivation during wheat starch hydrolysis process  

Microsoft Academic Search

The work reported here investigates the effects of operating conditions on enzymic hydrolysis of wheat starch. A commercial ?-amylase enzyme (Gemsize 4A, produced by Bacillus subtilis) was used for the hydrolysis experiments. The degree of hydrolysis (%) and ?-amylase activity (%) were investigated versus the process variables, pH, temperature, viscosity, amount of enzyme preparation added, impeller speed, amount of hydrolysate

Belma Özbek; Semra Yüceer

2001-01-01

117

Chemical recycling of poly(ethylene terephthalate) (PET) by hydrolysis and glycolysis.  

PubMed

In this paper we review an interesting method of PET recycling, i.e. chemical recycling; it is based on the concept of depolymerizing the condensation polymer through solvolytic chain cleavage into low molecular products which can be purified and reused as raw materials for the production of high-quality chemical products. In this work our attention is confined to the hydrolysis (neutral, acid and alkaline) and glycolysis processes of PET chemical recycling; operating conditions and mechanism of each method are reported and described. The neutral hydrolysis has an auto accelerating character; two kinetic models have been proposed: an half-order and a second order kinetic model. The acid hydrolysis could be explained by a modified shrinking core model under chemical reaction control and the alkaline hydrolysis by a first-order model with respect to hydroxide ion concentration. To describe glycolysis, two different kinetic models have been proposed where EG can act or not as internal catalyst. Further experimental and theoretical investigations are required to shed light on the promising processes of PET chemical recycling reviewed in this work. PMID:14699998

Carta, Daniela; Cao, Giacomo; D'Angeli, Claudio

2003-01-01

118

Kinetic studies of enzymatic hydrolysis of insoluble cellulose: (II) analysis of extended hydrolysis times  

Microsoft Academic Search

The kinetics of enzymatic hydrolysis of pure insoluble cellulose by means of unpurified culture filtrate of Trichoderma reesei was studied, emphasizing the kinetic characteristics associated wit the extended hydrolysis times. The changes in the hydrolysis rate and extent of soluble protein ad sorption during the progress of reaction, either apparent or intrinsic, were investigated. The hydrolysis rate declined drastically during

Yong-Hyun Lee; L. T. Fan

1983-01-01

119

Protein hydrolysis by immobilized and stabilized trypsin.  

PubMed

The preparation of novel immobilized and stabilized derivatives of trypsin is reported here. The new derivatives preserved 80% of the initial catalytic activity toward synthetic substrates [benzoyl-arginine p-nitroanilide (BAPNA)] and were 50,000-fold more thermally stable than the diluted soluble enzyme in the absence of autolysis. Trypsin was immobilized on highly activated glyoxyl-Sepharose following a two-step immobilization strategy: (a) first, a multipoint covalent immobilization at pH 8.5 that only involves low pK(a) amino groups (e.g., those derived from the activation of trypsin from trypsinogen) is performed and (b) next, an additional alkaline incubation at pH 10 is performed to favor an intense, additional multipoint immobilization between the high concentration of proximate aldehyde groups on the support surface and the high pK(a) amino groups at the enzyme surface region that participated in the first immobilization step. Interestingly, the new, highly stable trypsin derivatives were also much more active in the proteolysis of high molecular weight proteins when compared with a nonstabilized derivative prepared on CNBr-activated Sepharose. In fact, all the proteins contained a cheese whey extract had been completely proteolyzed after 6 h at pH 9 and 50°C, as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). Under these experimental conditions, the immobilized biocatalysts preserve more than 90% of their initial activity after 20 days. Analysis of the three-dimensional (3D) structure of the best immobilized trypsin derivative showed a surface region containing two amino terminal groups and five lysine (Lys) residues that may be responsible for this novel and interesting immobilization and stabilization. Moreover, this region is relatively far from the active site of the enzyme, which could explain the good results obtained for the hydrolysis of high-molecular weight proteins. PMID:21509952

Marques, Daniela; Pessela, Benavides C; Betancor, Lorena; Monti, Rubens; Carrascosa, Alfonso V; Rocha-Martin, Javier; Guisán, Jose M; Fernandez-Lorente, Gloria

2011-04-20

120

Cellulase hydrolysis of unsorted MSW.  

PubMed

A recent development in waste management and engineering has shown that the cellulase can be used for the liquefaction of organic fractions in household waste. The focus of this study was to optimize the enzyme hydrolysis of thermally treated municipal solid waste (MSW) by the addition of surfactant. Concurrently, the enzyme performance was analysed on pure cellulose in a solution of MSW wastewater. Results showed no effect of surfactant addition to the hydrolysis media as measured by viscosity and particle size distribution. MSW treatment wastewater was found to contain a high amount of calcium, potassium, sodium, chloride and others that may affect cellulolytic enzymes. Cellulase performance showed no effect of adding the metal ion-chelating agent EDTA to the solution. The cellulases were stable, tolerated and functioned in the presence of several contaminants. PMID:21989799

Jensen, Jacob Wagner; Felby, Claus; Jørgensen, Henning

2011-10-12

121

Study of kinetic parameters in a mechanistic model for enzymatic hydrolysis of sugarcane bagasse subjected to different pretreatments.  

PubMed

The goal of this work is to evaluate the influence of different pretreatments in the kinetics of enzymatic hydrolysis of sugarcane bagasse and to propose a reliable methodology to easily perform sensitivity analysis and updating kinetic parameters whenever necessary. A kinetic model was modified to represent the experimental data of the batch enzymatic hydrolysis of sugarcane bagasse pretreated with alkaline hydrogen peroxide. The simultaneous estimation of kinetic parameters of the mathematical model was performed using the Pikaia genetic algorithm using batch hydrolysis experimental data obtained with different enzymatic loads. Subsequently, Plackett-Burman designs were used to identify the kinetic parameters with the higher influence on the dynamic behavior of the process variables, which were re-estimated to describe experimental data of the hydrolysis of bagasse pretreated with phosphoric acid + sodium hydroxide. The methodology was accurate and straightforward and can be used whenever there are changes in pretreatment conditions and/or fluctuations in biomass composition in different harvests. PMID:23474967

Neto, João Moreira; Dos Reis Garcia, Daniella; Rueda, Sandra Marcela Gómez; da Costa, Aline Carvalho

2013-03-09

122

Cobalt boride catalysts for hydrogen generation from alkaline NaBH 4 solution  

Microsoft Academic Search

Cobalt boride precursors were synthesized via chemical reaction of aqueous sodium borohydride with cobalt chloride, and followed by heat-treating at various temperatures. The as-prepared Co–B catalysts were characterized and analyzed by X-ray diffraction (XRD), nitrogen adsorption–desorption and catalytic activity test; and were adopted to help accelerating hydrolysis reaction of NaBH4 alkaline solution. The Co–B catalyst treated at 500 °C exhibits

Chuan Wu; Feng Wu; Ying Bai; Baolian Yi; Huamin Zhang

2005-01-01

123

Inhibition kinetics of green crab ( Scylla serrata) alkaline phosphatase activity by dithiothreitol or 2-mercaptoethanol  

Microsoft Academic Search

Green crab (Scylla serrata) alkaline phosphatase (EC 3.1.3.1) is a metalloenzyme which catalyzes the nonspecific hydrolysis of phosphate monoesters. Some pollutants in seawater affect the enzyme activity causing loss of the biological function of the enzyme, which affects the exuviating crab-shell and threatens the survival of the animal. The present paper studies the effects of thiohydroxyal compounds on the activity

Rong-Qing Zhang; Qing-Xi Chen; Wen-Zhu Zheng; Jing-Yu Lin; Zhong-Lai Zhuang; Hai-Meng Zhou

2000-01-01

124

Effects of amines and aminoalcohols on bovine intestine alkaline phosphatase activity  

Microsoft Academic Search

Bovine intestine alkaline phosphatase (BIALP) is widely used as a signaling enzyme in sensitive assays such as enzyme immunoassay (EIA). In this study, we evaluated the effects of various aminoalcohols and amines on the activity of BIALP in the hydrolysis of p-nitrophenyl phosphate (pNPP) at pH 9.8, at 20°C. The kcat values at 0.05M diethanolamine, 0.1M triethanolamine, and 0.2M N-methylethanolamine

Satoshi Sekiguchi; Yasuhiko Hashida; Kiyoshi Yasukawa; Kuniyo Inouye

2011-01-01

125

Hydrogen generation utilizing alkaline sodium borohydride solution and supported cobalt catalyst  

Microsoft Academic Search

Supported Co catalysts with different supports were prepared for hydrogen generation (HG) from catalytic hydrolysis of alkaline sodium borohydride solution. As a result, we found that a ?-Al2O3 supported Co catalyst was very effective because of its special structure. A maximum HG rate of 220mLmin?1g?1 catalyst and approximately 100% efficiency at 303K were achieved using a Co\\/?-Al2O3 catalyst containing 9wt.%

Wei Ye; Huamin Zhang; Dongyan Xu; Li Ma; Baolian Yi

2007-01-01

126

Hydrolysis of Hexanitrohexaazaisowurtzitane (CL20)  

Microsoft Academic Search

The hydrolysis of the ?, ?, and ? polymorphs of 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane(CL-20) was investigated in dilute buffered aqueous solutions over a pH range of 4–10 and at 35, 43, 50, 58 and 65°C, with starting concentrations of CL-20 at one half the solubility limit for the respective temperature. In all cases, an overall first-order kinetic behavior was observed. The rate constants,

Julius Pavlov; Christos Christodoulatos; Mohammed Sidhoum; Steven Nicolich; Wendy Balas; Agamemnon Koutsospyros

2007-01-01

127

The chlorination of hydrolysis lignin  

Microsoft Academic Search

Summary 1.Technical hydrolysis lignin is easily chlorinated at 20° by solutions of chlorine in carbon tetrachloride or by chlorine water. When 25–27% of chlorine is introduced, the latter is quantitatively removed from the solution by the lignin.2.The chlorine content of products chlorinated in carbon tetrachloide is very close to that required by calculation for the substitution reaction.3.When lignin is chlorinated

N. N. Shorygina; L. I. Kolotova

1953-01-01

128

Hydrolysis of titanium sulphate compounds  

Microsoft Academic Search

The influence of TiOSO4 and free sulphuric acid concentrations in the starting solution on the degree of titanyl sulphate conversion to hydrated\\u000a titanium dioxide and post-hydrolytic sulphuric acid was studied. Titanyl sulphate solution, an intermediate product in the\\u000a commercial preparation of titanium dioxide pigments by sulphate route, was used. It was found that the degree of hydrolysis\\u000a markedly depends on

Barbara U. Grzmil; Daniel Grela; Bogumi? Kic

2008-01-01

129

HYDROLYSIS  

EPA Science Inventory

Hydrolytic processes provide the baseline loss rate for any chemical in an aqueous envi- ronment. Although various hydrolytic pathways account for significant degradation of certain classes of organic chemicals, other organic structures are completely inert. Strictly speaking, hy...

130

Molecular and biochemical characterization of a new alkaline active multidomain xylanase from alkaline wastewater sludge.  

PubMed

A xylanase gene, xyn-b39, coding for a multidomain glycoside hydrolase (GH) family 10 protein was cloned from the genomic DNA of the alkaline wastewater sludge of a paper mill. Its deduced amino acid sequence of 1,481 residues included two carbohydrate-binding modules (CBM) of family CBM_4_9, one catalytic domain of GH 10, one family 9 CBM and three S-layer homology (SLH) domains. xyn-b39 was expressed heterologously in Escherichia coli, and the recombinant enzyme was purified and characterized. Xyn-b39 exhibited maximum activity at pH 7.0 and 60 °C, and remained highly active under alkaline conditions (more than 80 % activity at pH 9.0 and 40 % activity at pH 10.0). The enzyme was thermostable at 55 °C, retaining more than 90 % of the initial activity after 2 h pre-incubation. Xyn-b39 had wide substrate specificity and hydrolyzed soluble substrates (birchwood xylan, beechwood xylan, oat spelt xylan, wheat arabinoxylan) and insoluble substrates (oat spelt xylan and wheat arabinoxylan). Hydrolysis product analysis indicated that Xyn-b39 was an endo-type xylanase. The K (m) and V (max) values of Xyn-b39 for birchwood xylan were 1.01 mg/mL and 73.53 U/min/mg, respectively. At the charge of 10 U/g reed pulp for 1 h, Xyn-b39 significantly reduced the Kappa number (P < 0.05) with low consumption of chlorine dioxide alone. PMID:23117673

Zhao, Yanyu; Meng, Kun; Luo, Huiying; Huang, Huoqing; Yuan, Tiezheng; Yang, Peilong; Yao, Bin

2012-11-02

131

Utilization of pineapple stem juice to enhance enzyme-hydrolytic efficiency for sugarcane bagasse after an optimized pre-treatment with alkaline peroxide  

Microsoft Academic Search

The enzymatic hydrolysis of sugarcane bagasse was investigated by treating a peroxide–alkaline bagasse with a pineapple stem juice, xylanase and cellulase. Pre-treatment procedures of sugarcane bagasse with alkaline hydrogen peroxide were evaluated and compared. Analyses were performed using 24 factorial designs, with pre-treatment time, temperature, magnesium sulfate and hydrogen peroxide concentration as factors. The responses evaluated were the yield of

J. R. Monte; M. Brienzo; A. M. F. Milagres

2011-01-01

132

Hydrolases in Polymer Chemistry: Part III: Synthesis and Limited Surface Hydrolysis of Polyesters and Other Polymers  

NASA Astrophysics Data System (ADS)

Limited enzymatic surface hydrolysis of polyamides, polyethyleneterphthalates (PET) and polyacrylonitriles has been demonstrated to be a powerful and yet mild strategy for directly improving polymer surface properties (e.g., hydrophilicity) or activating materials for further processing. Recently, mechanistic details on enzymatic surface hydrolysis have become available, especially for the functionalisation of PET, which has been investigated in most detail. Generally, enzymes show a strong preference for amorphous regions of polymers. Consequently, during hydrolysis, the degree of crystallinity increases according to FTIR and DSC analysis. MALDI-TOF analysis has shown that PET hydrolases (i.e. cutinases and lipases) cleave the polymer endo-wise, in contrast to alkaline hydrolysis. As a result, an increase in the amount of carboxyl and hydroxyl groups has been found upon enzymatic hydrolysis, according to X-ray photoelectron spectroscopy and various derivatisation and titration methods recently adapted for this purpose. These mechanistic data, combined with advances in structural and molecular biology, help to explain the considerably different activities of closely related enzymes (e.g. cutinases) on polymers.

Guebitz, Georg M.

133

Functional characterisation and transcript analysis of an alkaline phosphatase from the arbuscular mycorrhizal fungus Funneliformis mosseae.  

PubMed

Alkaline phosphatases (ALP) in arbuscular mycorrhizal (AM) fungi have been suggested to be involved in transfer of phosphate from the mycorrhizal fungus to the host plant, but exact mechanisms are still unknown, partially due to the lack of molecular information. We isolated a full-length cDNA (FmALP) from the AM fungus Funneliformis mosseae (syn. Glomus mosseae) showing similarity with putative ALP genes from Rhizophagus intraradices (syn. Glomus intraradices) and Gigaspora margarita. For functional characterisation FmALP was expressed heterologously in the yeast Pichia pastoris. The recombinant FmALP protein had a pH optimum of 9.5, and catalysed the hydrolysis of glycerolphosphate and, to a lesser extent of glucose-1- and 6-phosphate, confirming it to be an alkaline phosphatase belonging to the family of alkaline phosphomonoesterases (EC 3.1.3.1). FmALP did not catalyse the hydrolysis of ATP or polyP. Relative FmALP transcript levels were analysed in intra- and extraradical hyphae isolated from F. mosseae infected ryegrass (Lolium perenne) using reverse transcription-quantitative polymerase chain reaction (RT-qPCR). FmALP was highly expressed in intraradical hyphae at low P(i) supply, and its expression was repressed by high P(i) supply. Taken together this study provides evidence for mycorrhizal alkaline phosphatases playing a role in P mobilisation from organic substrates under P starvation conditions. PMID:23474124

Liu, Qianhe; Parsons, Anthony J; Xue, Hong; Jones, Chris S; Rasmussen, Susanne

2013-03-05

134

Enhanced polysaccharide recovery from agricultural residues and perennial grasses treated with alkaline hydrogen peroxide.  

PubMed

Pretreatment of lignocellulosic materials with alkaline hydrogen peroxide greatly increases their susceptibility to enzymatic cellulose hydrolysis. During the course of the pretreatment reaction (18 h), the pH rises slowly, increasing from pH 11.5 to a final pH > 12. As a result, most of the hemicellulose in the lignocellulosic substrate becomes solubilized. Maintaining the reaction pH near the optimum of 11.5 prevents hemicellulose solubilization and decreases the time required for effective pretreatment to about 6 h. Alkaline peroxide pretreatment is most effective on lignocellulose from monocotyledonous plants, especially members of the family Gramineae. Enzymatic saccharification efficiencies > 90% of theoretical were attained from high yielding perennial grasses such as big bluestem (Andropogon gerardi) and Indian grass (Sorghastrum nutans) after alkaline peroxide pretreatment. PMID:18553753

Gould, J M

1985-06-01

135

ATP and ADP hydrolysis in cell membranes from rat myometrium.  

PubMed

Extracellular nucleotides affect female reproductive functions, fertilization, and pregnancy. The aim of this study was to investigate biochemical characteristics of ATP and ADP hydrolysis and identify E-NTPDases in myometrial cell membranes from Wistar albino rats. The apparent K (m) values were 506.4 ± 62.1 and 638.8 ± 31.3 ?M, with a calculated V (max) (app) of 3,973.0 ± 279.5 and 2,853.9 ± 79.8 nmol/min/mg for ATP and ADP, respectively. The enzyme activity described here has common properties characteristic for NTPDases: divalent cation dependence; alkaline pH optimum for both substrates, insensitivity to some of classical ATPase inhibitors (ouabain, oligomycine, theophylline, levamisole) and significant inhibition by suramine and high concentration of sodium azides (5 mM). According to similar apparent K(m) values for both substrates, the ATP/ADP hydrolysis ratio, and Chevillard competition plot, NTPDase1 is dominant ATP/ADP hydrolyzing enzyme in myometrial cell membranes. RT-PCR analysis revealed expression of three members of ectonucleoside triphosphate diphosphohydrolase family (NTPDase 1, 2, and 8) in rat uterus. These findings may further elucidate the role of NTPDases and ATP in reproductive physiology. PMID:22956447

Miloševi?, Maja; Petrovi?, Snježana; Veli?kovi?, Nataša; Grkovi?, Ivana; Ignjatovi?, Marija; Horvat, Anica

2012-09-07

136

Increase in ethanol production from sugarcane bagasse based on combined pretreatments and fed-batch enzymatic hydrolysis.  

PubMed

Enzymatic hydrolysis of pretreated sugarcane bagasse was performed to investigate the production of ethanol. The sugarcane bagasse was pretreated in a process combining steam explosion and alkaline delignification. The lignin content decreased to 83%. Fed-batch enzymatic hydrolyses was initiated with 8% (w/v) solids loading, and 10 FPU/g cellulose. Then, 1% solids were fed at 12, 24 or 48 h intervals. After 120 h, the hydrolysates were fermented with Saccharomyces cerevisiae UFPEDA 1238, and a fourfold increase in ethanol production was reached when fed-batch hydrolysis with a 12-h addition period was used for the steam pretreated and delignified bagasse. PMID:23201527

Wanderley, Maria Carolina de Albuquerque; Martín, Carlos; Rocha, George Jackson de Moraes; Gouveia, Ester Ribeiro

2012-11-03

137

Zinc electrode in alkaline electrolyte  

SciTech Connect

The zinc electrode in alkaline electrolyte is unusual in that supersaturated zincate solutions can form during discharge and spongy or mossy zinc deposits can form on charge at low overvoltages. The effect of additives on regular pasted ZnO electrodes and calcium zincate electrodes is discussed. The paper also reports on in situ x-ray absorption (XAS) results on mossy zinc deposits.

McBreen, J.

1995-12-31

138

Alkaline solution water electrolysis - '81  

Microsoft Academic Search

During the last two years several improvements in the alkaline solution electrolysis technology have been implemented in form of practical hardware. Attention is given to the catalyst system 'C-AN', alternative anode structures, a new proprietary anode electrocatalyst, alternates to the conventional chrysotile asbestos separator, the current status of hardware development, and the employment of simplistic and complex models for establishing

J. N. Murray

1981-01-01

139

Alkaline detergent recycling via ultrafiltration  

Microsoft Academic Search

The metal finishing industry uses alkaline cleaners and detergents to remove oils and dirt from manufactured parts, often before they are painted or plated. The use of these cleaners has grown because environmental regulations are phasing out ozone depleting substances and placing restrictions on the use and disposal of many hazardous solvents. Lawrence Livermore National Laboratory is examining ultrafiltration as

C. Steffani; M. Meltzer

1995-01-01

140

Alkaline rocks from continental Brazil  

NASA Astrophysics Data System (ADS)

The present literature review on Brazilian alkaline rocks stresses mainly the petrographic and geologic aspects. At least eight different rock associations are represented. Agewise, four groups are found among southern Brazilian outcrops: an older one, about 240 m.y. only, that is still poorly known; the massifs clustered around Jacupiranga, about 130 m.y. old; a few occurrences 100-110 m.y. old (Tunas, Itapirapua); and the youngest and most important one, with an age spread from about 80 m.y. to about 53 m.y. Recent research shows a clear tectonic control — both on local and on regional scales — of alkaline occurrences in southern Brazil. Alkaline magmatism was set off by pre-drift and drift activity and is, at its onset, geologically related to basaltic activity. Emplacement of many massifs is also locally controlled by old lineaments (e.g., in the Minas Gerais-Goiás belt), as is emphasized by geophysical data. On a petrographic and chronologic basis, several alkaline provinces are distinguished in southern Brazil. Preliminary data on the Cambrian-Precambrian rocks from southern Bahia State (a province with undersaturated syenites and litchfieldites) and from cratonic areas in northern Brazil are also presented.

Ulbrich, H. H. G. J.; Gomes, C. B.

1981-04-01

141

Subcellular localization of marine bacterial alkaline phosphatases  

PubMed Central

Bacterial alkaline phosphatases (APases) are important enzymes in organophosphate utilization in the ocean. The subcellular localization of APases has significant ecological implications for marine biota but is largely unknown. The extensive metagenomic sequence databases from the Global Ocean Sampling Expedition provide an opportunity to address this question. A bioinformatics pipeline was developed to identify marine bacterial APases from the metagenomic databases, and a consensus classification algorithm was designed to predict their subcellular localizations. We identified 3,733 bacterial APase sequences (including PhoA, PhoD, and PhoX) and found that cytoplasmic (41%) and extracellular (30%) APases exceed their periplasmic (17%), outer membrane (12%), and inner membrane (0.9%) counterparts. The unexpectedly high abundance of cytoplasmic APases suggests that the transport and intracellular hydrolysis of small organophosphate molecules is an important mechanism for bacterial acquisition of phosphorus (P) in the surface ocean. On average, each marine bacterium possessed at least one suite of uptake of glycerol phosphate (ugp) genes (e.g., ugpA, ugpB, ugpC, ugpE) for dissolved organic phosphorus (DOP) transport, but only half of them had ugpQ, which hydrolyzes transported DOP, indicating that cytoplasmic APases play a role in hydrolyzing transported DOP. The most abundant heterotrophic marine bacteria, ?- and ?-Proteobacteria, might hydrolyze DOP outside the cytoplasmic membrane, but the former could also transport and hydrolyze DOP in the cytoplasm. The abundant extracellular APases could provide bioavailable P for organisms that cannot directly access organophosphates, and thereby increase marine biological productivity and diversity.

Luo, Haiwei; Benner, Ronald; Long, Richard A.; Hu, Jianjun

2009-01-01

142

Low temperature hydrolysis for ethanol production  

SciTech Connect

Hydrolysis of corn was compared at two temperatures of 100/sup 0/C and 75/sup 0/C. Starch conversion to dextrose and then ethanol were determined. Yields were 10.69% ethanol in the fermented beer for 100/sup 0/C and 9.89% for 75/sup 0/C. The 75/sup 0/C hydrolysis required about 100 MJ less thermal energy than the 100/sup 0/C hydrolysis. The effects of contamination and respiration were also assessed.

Garcia, A.; Fischer, J.R.; Iannotti, E.L.

1982-12-01

143

ORGANOPHOSPHATE AND ORGANOPHOSPHOROTHIONATE ESTERS: APPLICATION OF LINEAR FREE ENERGY RELATIONSHIPS TO ESTIMATE HYDROLYSIS RATE CONSTANTS FOR USE IN ENVIRONMENTAL FATE ASSESSMENT  

EPA Science Inventory

Hydrolysis rate constants required for assessing the environmental fate of certain organophosphate and organophosphorothionate esters may be estimated by use of linear free energy relationships (LFERs). LFERs for the second-order alkaline rate constants and the pKa of the conjuga...

144

TLC determination of meloxicam in tablets and after acidic and alkaline hydrolysis.  

PubMed

A simple and rapid method for separation and determination of meloxicam and its degradation products by thin-layer chromatography with densitometric detection in pharmaceutical preparations was described. The method employed TLC F254 plates as the stationary phase. The solvent system consisted of ethyl acetate : toluene : butylamine (2:2:1, v/v/v). Densitometric analysis was carried out in absorbance mode at wavelength of 297 nm. The method was validated for linearity, precision and accuracy. The limits of detection and determination were 0.96 ?g per spot and 2.90 ?g per spot, respectively. The drug was degraded in acidic and basic environment, at different temperatures. The degradation products were well resolved from the active substance. The HPLC-MS/MS method for the identification of degradation products of meloxicam (i.e. 5-methylthiazol- 2-ylamine and 5-(dioxide-l(6)-sulfanylidene)-6-methylidenecyclohexa-1,3-diene) was investigated. Because the presented method allows the efficient separation of the drug from some of its degradation products, so it can be used as a stability-indicating analysis. PMID:22568036

Starek, Ma?gorzata; Krzek, Jan

145

Mechanisms of hydrolysis-oligomerization of aluminum alkoxide Al(OC3H7)3.  

PubMed

As one of the representative superinsulating materials, the aluminum trioxypropyl Al(OC(3)H(7))(3) aerogel may be applied in launch vehicles and manned spacecrafts. In this study, the structures and hydrolysis mechanisms of the monomer, dimers, and trimers of Al(OC(3)H(7))(3) in neutral and alkaline environments were studied at the B3LYP/6-31G(d,p) level by using the CPCM solvation model to understand the fundamental chemistry of Al(OC(3)H(7))(3) hydrolysis and oligomerization. Our calculation shows that the first-order hydrolyses of the monomer and oligomers are energetically favorable in both alkaline and neutral solutions. In alkaline solutions, they are more apt to oligomerize than to hydrolyze due to high energy barriers and large binding energies in the formation of anionic species. For the oligomers under neutral condition (1) Al(OC(3)H(7))(3) is linked by four-membered Al-O rings with pentacoordinated bridging and tetracoordinated Al atoms, (2) the hydrolyzed propoxy groups will be expelled by solvent molecules, and (3) partly hydrolyzed species can condense to oligomers with bridging OH groups or O atoms. PMID:21500848

Cheng, Xueli; Liu, Yongjun; Chen, Dairong

2011-04-18

146

The use of ultra high-performance liquid chromatography for studying hydrolysis kinetics of CL-20 and related energetic compounds.  

PubMed

Ultra high-performance liquid chromatography (UHPLC) utilizes columns packed with sub-2-mum stationary-phase particles and allows operation with pressures of up to 15,000 psi to yield increased resolution, speed, and sensitivity versus conventional HPLC. This promising new technology was used for the analysis of energetic compounds (RDX, HMX and CL-20) and a selective method was developed on an Acquity UPLC. A fast UHPLC method was applied to determine alkaline hydrolysis reaction kinetics of major energetic compounds. Activation energies of alkaline hydrolysis reaction for CL-20, RDX and HMX were comparable to those in literature, however they were determined in a shorter amount of time due to the speed of analysis of the chromatographic method. The use of liophilic salts (KPF(6)) as mobile-phase additives for the enhancement of separation selectivity of energetic compounds was demonstrated. PMID:18644671

Makarov, Alexey; Lobrutto, Rosario; Christodoulatos, Christos; Jerkovich, Anton

2008-06-11

147

Column cellulose hydrolysis reactor: Cellulase adsorption profile  

Microsoft Academic Search

A column cellulose hydrolysis reactor was set up using a single passage of cellulase enzyme which was followed with a continuous percolation of buffer. Hydrolysis rates were found to decline precipitously upon the removal of the non-adsorbed cellulase components. By comparing specific activities of the cellulase before and after adsorption on the cellulose column, it was concluded that the adsorption

Larry U. L. Tan; Ernest K. C. Yu; Paul Mayers; John N. Saddler

1986-01-01

148

Hydrolysis of Bromodifluoro-methyltriphenylphosphonium Bromide.  

National Technical Information Service (NTIS)

Hydrolysis of Ph3P(+)CF2BrBr(-) afforded a high yield of bromodifluoromethane and triphenylphosphine oxide. Hydrolysis in the presence of a radioactive isotope of bromine or sodium iodide gave unequivocal evidence that the mechanism for this reaction proc...

D. J. Burton R. M. Flynn R. G. Manning R. M. Kessler

1982-01-01

149

?-Amylase inactivation during rice starch hydrolysis  

Microsoft Academic Search

The effects of operating conditions on the enzymatic hydrolysis of rice starch were investigated using a commercial ?-amylase produced by Bacillus spp. in a stirred batch reactor. The degree of starch hydrolysis (%) and residual ?-amylase activity (%) were investigated versus process variables including pH, temperature, viscosity, impeller speed, processing time and some materials added such as hydrolysate, maltose, glucose,

Dilek K?l?ç Apar; Belma Özbek

2005-01-01

150

Oil Recovery by Alkaline Waterflooding  

Microsoft Academic Search

Flooding of oil containing organic acids with alkaline water under favorable conditions can result in recovery of around 50% of the residual oil left in a watered-out model. A high recovery efficiency results from the formation of a bank of viscous water-in-oil emulsion as surface active agents (soaps) are created by reactions of base in the water with the organic

R. E. Williams; P. A. Kolodzie

1974-01-01

151

Alkaline solution water electrolysis - '81  

NASA Astrophysics Data System (ADS)

During the last two years several improvements in the alkaline solution electrolysis technology have been implemented in form of practical hardware. Attention is given to the catalyst system 'C-AN', alternative anode structures, a new proprietary anode electrocatalyst, alternates to the conventional chrysotile asbestos separator, the current status of hardware development, and the employment of simplistic and complex models for establishing the economics of hydrogen via water electrolysis.

Murray, J. N.

152

In vitro phosphorylation of acetylcholinesterase at non-consensus protein kinase A sites enhances the rate of acetylcholine hydrolysis  

Microsoft Academic Search

Here, we report that the catalytic subunit of cAMP-dependent protein kinase (PKA) but not casein kinase II or protein kinase C phosphorylates recombinant human acetylcholinesterase (AChE) in vitro. This enhances acetylthiocholine hydrolysis up to 10-fold as compared to untreated AChE, while leaving unaffected the enzyme's affinity for this substrate and for various active and peripheral site inhibitors. Alkaline phosphatase treatment

Mirta Grifman; Ayelet Arbel; Dalia Ginzberg; David Glick; Sharona Elgavish; Boaz Shaanan; Hermona Soreq

1997-01-01

153

Detection of sarin hydrolysis products from sarin-like organophosphorus agent-exposed human erythrocytes.  

PubMed

A sarin-like organophosphorus agent, [bis(isopropyl methyl)phosphonate; BIMP], was synthesized. This agent has the same phosphonate group as sarin and also has the same anti-acetylcholinesterase activity potency as sarin. The ID50 and LD50 values of BIMP in mice after intravenous injection were 3.9 nM and 0.8 mg/kg, respectively. The AChE activities of their red blood cells and brains were dose-dependently reduced by intravenous BIMP. After preparation of experimental BIMP-exposed human red blood cells, BIMP-bound acetylcholinesterase (AChE) was solubilized from erythrocyte membranes, purified by immunoaffinity chromatography, digested with trypsin, and the sarin hydrolysis products bound to AChE were released by alkaline phosphatase digestion. The digested sarin hydrolysis products were subjected to trimethylsilyl (TMS) derivatization and detected by gas chromatography-mass spectrometry. Isopropyl methylphosphonic- and methylphosphonic acids, which are the sarin hydrolysis products, were detected in experimental BIMP-exposed human red blood cells. This new method, which enables sarin's hydrolysis products to be detected in BIMP-exposed erythrocytes, is a useful tool for studying sarin-poisoning victims. PMID:9389333

Nagao, M; Takatori, T; Matsuda, Y; Nakajima, M; Niijima, H; Iwase, H; Iwadate, K; Amano, T

1997-11-01

154

Spectrophotometric and liquid chromatographic determination of fenofibrate and vinpocetine and their hydrolysis products.  

PubMed

Several spectrophotometric and HPLC methods are presented for the determination of fenofibrate, vinpocetine and their hydrolysis products. The resolution of either fenofibrate or vinpocetine and their hydrolysis products has been accomplished by using numerical spectrophotometric methods as partial least squares (PLS-1) and principal component regression (PCR) applied to UV spectra; and graphical spectrophotometric methods as first derivative of ratio spectra (1DD) or first (1D) and second (2D) derivative spectrophotometry for vinpocetine and fenofibrate, respectively. In addition HPLC methods were developed using ODS column with mobile phase consisting of acetonitrile-water (80:20, v/v, pH 4) with UV detection at 287 nm for fenofibrate and a mobile phase consisting of acetonitrile-10 mM KH2PO4, containing 0.1% diethylamine (60:40, v/v, pH 4.6) with UV detection at 270 nm for vinpocetine. The proposed methods were successfully applied for the determination of each drug and its hydrolysis product in laboratory-prepared mixture and pharmaceutical preparation. The proposed HPLC and derivative spectrophotometric methods were used to investigate the kinetics of acidic and alkaline hydrolytic processes of each drug. The pH-rate profile of hydrolysis of each drug in Britton-Robinson buffer solutions was studied. PMID:15910815

El-Gindy, Alaa; Emara, Samy; Mesbah, Mostafa K; Hadad, Ghada M

2005-05-01

155

Effect of lime pre-treatment on the synergistic hydrolysis of sugarcane bagasse by hemicellulases.  

PubMed

Agricultural crop wastes are typically lignocellulosic in composition and thus partially recalcitrant to enzymatic degradation. The recalcitrant nature of plant biomass and the inability to obtain complete enzymatic hydrolysis has led to the establishment of various pre-treatment strategies. Alkaline pre-treatments increase the accessibility of the exposed surface to enzymatic hydrolysis through the removal of acetyl and uronic acid substituents on hemicelluloses. Unlike the use of steam and acid pre-treatments, alkaline pre-treatments (e.g. lime) solubilise lignin and a small percentage of the hemicelluloses. The most common alkaline pre-treatments that are employed make use of sodium hydroxide and lime. This study compared the synergistic degradation of un-treated and lime pre-treated sugarcane bagasse using cellulosomal and non-cellulosomal hemicellulases as free enzymes. The enzyme combination of 37.5% ArfA and 62.5% ManA produced the highest amount of reducing sugar of 91.834 micromol/min for the degradation of un-treated bagasse. This enzyme combination produced a degree of synergy of 1.87. The free enzymes displayed an approximately 6-fold increase in the enzyme activity, i.e. the total amount of reducing sugar released (593.65 micromol/min) with the enzyme combination of 37.5% ArfA, 25% ManA and 37.5% XynA for the lime pre-treated substrate and a degree of synergy of 2.14. To conclude, this study indicated that pre-treating the sugarcane bagasse is essential, in order to increase the efficiency of lignocellulose enzymatic hydrolysis by disruption of the lignin sheath, that the lime pre-treatment did not have any dramatic effect on the synergistic relationship between the free enzymes, and that time may play an important role in the establishment of synergistic relationships between enzymes. PMID:20156678

Beukes, Natasha; Pletschke, Brett I

2010-02-13

156

Modeling intrinsic kinetics of enzymatic cellulose hydrolysis.  

PubMed

A multistep approach was taken to investigate the intrinsic kinetics of the cellulase enzyme complex as observed with hydrolysis of noncrystalline cellulose (NCC). In the first stage, published initial rate mechanistic models were built and critically evaluated for their performance in predicting time-course kinetics, using the data obtained from enzymatic hydrolysis experiments performed on two substrates: NCC and alpha-cellulose. In the second stage, assessment of the effect of reaction intermediates and products on intrinsic kinetics of enzymatic hydrolysis was performed using NCC hydrolysis experiments, isolating external factors such as mass transfer effects, physical properties of substrate, etc. In the final stage, a comprehensive intrinsic kinetics mechanism was proposed. From batch experiments using NCC, the time-course data on cellulose, cello-oligosaccharides (COS), cellobiose, and glucose were taken and used to estimate the parameters in the kinetic model. The model predictions of NCC, COS, cellobiose, and glucose profiles show a good agreement with experimental data generated from hydrolysis of different initial compositions of substrate (NCC supplemented with COS, cellobiose, and glucose). Finally, sensitivity analysis was performed on each model parameter; this analysis provides some insights into the yield of glucose in the enzymatic hydrolysis. The proposed intrinsic kinetic model parametrized for dilute cellulose systems forms a basis for modeling the complex enzymatic kinetics of cellulose hydrolysis in the presence of limiting factors offered by substrate and enzyme characteristics. PMID:17465526

Peri, Suma; Karra, Srinivas; Lee, Y Y; Karim, M Nazmul

2007-04-28

157

The hydrolysis and alkylation activities of S-(2-haloethyl)-L-cysteine analogs--evidence for extended half-life.  

PubMed

A series of S-(2-haloethyl)-L-cysteine derivatives, which are analogs of the proposed glutathione half-mustard metabolites of dihaloethanes, were synthesized and studied with respect to their hydrolysis and alkylation rates in aqueous solution. The trend of relative hydrolysis rates, Br greater than Cl much greater than F, paralleled their respective leaving group abilities; however, a dramatic rate increase was seen at pH 8 versus pH's 6 or 4. Hydrolysis of S-(2-chloroethyl)-L-cysteine analogs, where the ionizable groups were blocked (carboxyl esterified and/or N-acetylated), revealed that the amine moiety was responsible for the increased hydrolysis of mustard gas (beta, beta'-dichlorodiethyl sulfide) gave similar results with S-(2-chloroethyl)-L-cysteine, a finding which is consistent with the reaction intermediate being a highly charged species. The alkylation rates with 4-(p-nitrobenzyl)-pyridine were not affected by blocking the ionizable groups. A mechanism of internal cyclization is proposed to explain the accelerated alkaline hydrolysis rates noted with S-(2-haloethyl)-L-cysteines but not with the N-acetylated analogs (mercapturic acids). This scheme proposes the formation of 3-(thiomorpholine)-carboxylic acid as an alternative pathway to the generally accepted hydrolysis reaction. This compound and not S-(2-hydroxyethyl)-L-cysteine was the identified product following pH 10 hydrolysis. Increased hydrolysis half-time of amine-blocked cysteine analogs versus parent cysteine analogs may exist with S-(2-haloethyl)-glutathione derivatives which may explain the substantial nucleic acid alkylation seen with S-(2-haloethyl) derivatives of glutathione. PMID:6636172

Schasteen, C S; Reed, D J

1983-09-30

158

Kinetics of chitinase production. I. Chitin hydrolysis.  

PubMed

As part of the development of a comprehensive mathematical model for chitinase production by Serratia marcescens QMB 1466 growing on chitin, the different mass transport and kinetic steps involved during chitin hydrolysis were studied. The experimental results for the hydrolysis of chitin by a crude preparation of chitinase show a system kinetically limited by the overall rate of chitin hydrolysis. This rate is linearly related to the concentration of enzyme adsorbed on the chitin particle. Adsorbed and bulk enzyme concentration were found to be related through a Langmuir type of isotherm. PMID:18553734

Young, M E; Bell, R L; Carroad, P A

1985-06-01

159

Cellulose hydrolysis by immobilized Trichoderma reesei cellulase  

Microsoft Academic Search

Cellulose hydrolysis by immobilized Trichoderma reesei cellulase in the presence of a low viscosity ionic liquid, 1-ethyl-3-methylimidazolium diethyl phosphate (EMIM-DEP), was\\u000a investigated. Preparation of the carrier-free immobilized cellulase was optimized with respect to concentration of the cross-linker\\u000a and the type of precipitant. The addition of 2% (v\\/v) EMIM-DEP during hydrolysis gave an initial reaction rate 2.7 times higher\\u000a than the hydrolysis

Paetrice O. Jones; Palligarnai T. Vasudevan

2010-01-01

160

Actin Polymerization and ATP Hydrolysis  

NASA Astrophysics Data System (ADS)

F-actin is the major component of muscle thin filaments and, more generally, of the microfilaments of the dynamic, multifunctional cytoskeletal systems of nonmuscle eukaryotic cells. Polymeric F-actin is formed by reversible noncovalent self-association of monomeric G-actin. To understand the dynamics of microfilament systems in cells, the dynamics of polymerization of pure actin must be understood. The following model has emerged from recent work. During the polymerization process, adenosine 5'-triphosphate (ATP) that is bound to G-actin is hydrolyzed to adenosine 5'-diphosphate (ADP) that is bound to F-actin. The hydrolysis reaction occurs on the F-actin subsequent to the polymerization reaction in two steps: cleavage of ATP followed by the slower release of inorganic phosphate (Pi). As a result, at high rates of filament growth a transient cap of ATP-actin subunits exists at the ends of elongating filaments, and at steady state a stabilizing cap of ADP \\cdot Pi-actin subunits exists at the barbed ends of filaments. Cleavage of ATP results in a highly stable filament with bound ADP \\cdot Pi, and release of Pi destabilizes the filament. Thus these two steps of the hydrolytic reaction provide potential mechanisms for regulating the monomer-polymer transition.

Korn, Edward D.; Carlier, Marie-France; Pantaloni, Dominique

1987-10-01

161

Glucans from the alkaline extract of an edible mushroom, Pleurotus florida, cv Assam Florida: isolation, purification, and characterization.  

PubMed

Three different glucans (PS-I, PS-II, and PS-III) were isolated from the alkaline extract of the fruiting bodies of an edible mushroom Pleurotus florida, cultivar Assam Florida. On the basis of total acid hydrolysis, methylation analysis, periodate oxidation, Smith degradation, and NMR experiments ((1)H, (13)C, DEPT-135, DQF-COSY, TOCSY, NOESY, ROESY, HMQC, and HMBC), the structure of the repeating unit of these polysaccharides was established as follows: [Formula: see text]. PMID:20800223

Ojha, Arnab K; Chandra, Krishnendu; Ghosh, Kaushik; Islam, Syed S

2010-08-25

162

Alkaline detergent recycling via ultrafiltration  

SciTech Connect

The metal finishing industry uses alkaline cleaners and detergents to remove oils and dirt from manufactured parts, often before they are painted or plated. The use of these cleaners has grown because environmental regulations are phasing out ozone depleting substances and placing restrictions on the use and disposal of many hazardous solvents. Lawrence Livermore National Laboratory is examining ultrafiltration as a cleaning approach that reclaims the cleaning solutions and minimizes wastes. The ultrafiltration membrane is made from sheets of polymerized organic film. The sheets are rolled onto a supporting frame and installed in a tube. Spent cleaning solution is pumped into a filter chamber and filtered through the membrane that captures oils and dirt and allows water and detergent to pass. The membrane is monitored and when pressure builds from oil and dirt, an automatic system cleans the surface to maintain solution flow and filtration quality. The results show that the ultrafiltration does not disturb the detergent concentration or alkalinity but removed almost all the oils and dirt leaving the solution in condition to be reused.

Steffani, C.; Meltzer, M.

1995-06-01

163

Process design and optimization of cellulose hydrolysis  

SciTech Connect

The primary concern of this work is the economic optimization of a process for the hydrolysis of waste cellulosic material to fermentable sugars. Hydrolysis is performed enzymatically, utilizing the cellulase enzyme complex produced by Trichoderma viride. Using corn stover as a substrate, a system was designed to provide 14% hydrolyzate sugars (70% fermentable) at an estimated cost of 6.84 cents/pound of sugar, a 43% cost reduction over previous designs. Optimal residence time for hydrolysis was found to be 62 hours, resulting in a 34% conversion of raw material to sugars. Total fixed capital investment for the process is estimated to be $17.13 x 10/sup 6/. The kinetics of cellulose hydrolysis were modeled through the use of a modified Michaelis--Menten equation, making computer simulation of batch hydrolyses possible. Additional studies on the accessibility of cellulose were performed, and the feasibility of a counter-current processing scheme was investigated.

Lindsey, R.R.; Wilke, C.R.

1978-08-01

164

Cotton cellulose: enzyme adsorption and enzymic hydrolysis  

SciTech Connect

The adsorption of a crude cellulase complex from Trichoderma viride on variously pretreated cotton cellulose samples was studied in the framework of the Langmuir approach at 2-8 degrees. The saturation amount of adsorbed enzyme was related to the susceptibility of the substrates to hydrolysis. In every case the adsorption process was faster by 2-3 orders of magnitude than the hydrolysis step to give end products. For ZnCl/sub 2/-treated cotton cellulose the Langmuir parameters correlated fairly well with the value of the Michaelis constant, measured for its enzymic hydrolysis, and the adsorptive complex was indistinguishable from the complex of the Michaelis-Menten model for the hydrolysis.

Beltrame, P.L.; Carniti, P.; Focher, B.; Marzetti, A.; Cattaneo, M.

1982-01-01

165

Hydrolysis of Sucrose by Heterogeneous Catalysis  

Microsoft Academic Search

The reaction kinetics of the hydrolysis of sucrose by solid catalysts was investigated using polarimetry. Silica included heteropoly acid was used as a catalyst. At the optimizing conditions the activation parameters have been evaluated using the Arrhenius and Eyring plots.

H. Iloukhani; S. Azizian; N. Samadani

2002-01-01

166

Lipase-catalyzed hydrolysis of palm oil  

Microsoft Academic Search

The hydrolysis of palm oil, palm olein and palm stearin, soybean oil, corn oil and peanut oil by the commercial lipase fromCandida rugosa (formerly known asC. cylindracea) was studied. The optimal conditions for the hydrolysis of palm oil by the lipase were established. The lipase fromC. rugosa exhibits an optimal activity at 37 C and at pH 7.5. The optimal

H. T. Khor; N. H. Tan; C. L. Chua

1986-01-01

167

Lactose Utilization and Hydrolysis in Saccharomyces fragilis  

Microsoft Academic Search

SUMMARY Sodium azide, 2,4-dinitrophenol and iodoacetate did not inhibit hydrolysis of lactose by cell-free preparations of Sacchuromyces fragilis ,8-galactosidase, but with intact organisms fermentation and hydrolysis were inhibited to a similar extent. This suggests that these inhibitors may interfere with the transport of lactose into the cell. Galactose fermentation was inhibited by sodium azide and dinitrophenol to a much greater

R. DAVIES

1964-01-01

168

Alkaline and alkaline earth metal phosphate halides and phosphors  

SciTech Connect

Compounds, phosphor materials and apparatus related to nacaphite family of materials are presented. Potassium and rubidium based nacaphite family compounds and phosphors designed by doping divalent rare earth elements in the sites of alkaline earth metals in the nacaphite material families are descried. An apparatus comprising the phosphors based on the nacaphite family materials are presented herein. The compounds presented is of formula A.sub.2B.sub.1-yR.sub.yPO.sub.4X where the elements A, B, R, X and suffix y are defined such that A is potassium, rubidium, or a combination of potassium and rubidium and B is calcium, strontium, barium, or a combination of any of calcium, strontium and barium. X is fluorine, chlorine, or a combination of fluorine and chlorine, R is europium, samarium, ytterbium, or a combination of any of europium, samarium, and ytterbium, and y ranges from 0 to about 0.1.

Lyons, Robert Joseph; Setlur, Anant Achyut; Cleaver, Robert John

2012-11-13

169

Trypanosoma rangeli: An alkaline ecto-phosphatase activity is involved with survival and growth of the parasite.  

PubMed

The aim of this work was to investigate whether an alkaline ecto-phosphatase activity is present in the surface of Trypanosoma rangeli. Intact short epimastigote forms were assayed for ecto-phosphatase activity to study kinetics and modulators using ?-glycerophosphate (?-GP) and p-nitrophenyl phosphate (pNPP) as substrates. Its role in parasite development and differentiation was also studied. Competition assays using different proportions of ?-GP and pNPP evidenced the existence of independent and non-interacting alkaline and acid phosphatases. Hydrolysis of ?-GP increased progressively with pH, whereas the opposite was evident using pNPP. The alkaline enzyme was inhibited by levamisole in a non-competitive fashion. The Ca(2+) present in the reaction medium was enough for full activity. Pretreatment with PI-PLC decreased the alkaline but not the acid phosphatase evidence that the former is catalyzed by a GPI-anchored enzyme, with potential intracellular signaling ability. ?-GP supported the growth and differentiation of T. rangeli to the same extent as high orthophosphate (Pi). Levamisole at the IC50 spared significantly parasite growth when ?-GP was the sole source of Pi and stopped it in the absence of ?-GP, indicating that the alkaline enzyme can utilize phosphate monoesters present in serum. These results demonstrate the existence of an alkaline ecto-phosphatase in T. rangeli with selective requirements and sensitivity to inhibitors that participates in key metabolic processes in the parasite life cycle. PMID:23994113

Dos-Santos, André L A; Dick, Claudia F; Silveira, Thaís S; Fonseca-de-Souza, André L; Meyer-Fernandes, José R

2013-08-29

170

Treatment of cotton with an alkaline Bacillus spp cellulase: activity towards crystalline cellulose.  

PubMed

We analysed the influence of several enzymatic treatment processes using an alkaline cellulase enzyme from Bacillus spp. on the sorption properties of cotton fabrics. Although cellulases are commonly applied in detergent formulations due to their anti-redeposition and depilling benefits, determining the mechanism of action of alkaline cellulases on cotton fibres requires a deeper understanding of the morphology and structure of cotton fibres in terms of fibre cleaning. The accessibility of cellulose fibres was studied by evaluating the iodine sorption value and by fluorescent-labelled enzyme microscopy; the surface morphology of fabrics was analysed by scanning microscopy. The action of enzyme hydrolysis over short time periods can produce fibrillation on cotton fibre surface without any release of cellulosic material. The results indicate that several short consecutive treatments were more effective in increasing the fibre accessibility than one long treatment. In addition, no detectable hydrolytic activity, in terms of reducing sugar production, was found. PMID:21953804

Caparrós, Cristina; López, Carmen; Torrell, Marc; Lant, Neil; Smets, Johan; Cavaco-Paulo, Artur

2011-11-21

171

Anosmia in Alkaline Battery Workers  

PubMed Central

The sense of smell of 106 alkaline battery workmen exposed at their work to cadmium and nickel dust has been compared with a control group of 84 men matched for age. The battery workers reported significantly more anosmia than the controls (15% to zero) and did less well in the phenol smelling test (27·3% to 4·8%). Cadmium proteinuria was found in 17 of the battery workers, 11 of whom showed virtual anosmia. Figures of recent concentrations of cadmium and nickel in the atmosphere are given. The noses of 85 battery workers and 75 controls were examined. Signs of non-specific chronic irritation were more frequent in the battery workers but no significant relationship was established between this appearance and the presence of anosmia. It is concluded that the anosmia is due to exposure to cadmium or nickel dust or a mixture of the two.

Adams, R. G.; Crabtree, Norman

1961-01-01

172

A Novel Alkaline ?-Galactosidase from Melon Fruit with a Substrate Preference for Raffinose1  

PubMed Central

The cucurbits translocate the galactosyl-sucrose oligosaccharides raffinose and stachyose, therefore, ?-galactosidase (?-d-galactoside galactohydrolase, EC 3.2.1.22) is expected to function as the initial enzyme of photoassimilate catabolism. However, the previously described alkaline ?-galactosidase is specific for the tetrasaccharide stachyose, leaving raffinose catabolism in these tissues as an enigma. In this paper we report the partial purification and characterization of three ?-galactosidases, including a novel alkaline ?-galactosidase (form I) from melon (Cucumis melo) fruit tissue. The form I enzyme showed preferred activity with raffinose and significant activity with stachyose. Other unique characteristics of this enzyme, such as weak product inhibition by galactose (in contrast to the other ?-galactosidases, which show stronger product inhibition), also impart physiological significance. Using raffinose and stachyose as substrates in the assays, the activities of the three ?-galactosidases (alkaline form I, alkaline form II, and the acid form) were measured at different stages of fruit development. The form I enzyme activity increased during the early stages of ovary development and fruit set, in contrast to the other ?-galactosidase enzymes, both of which declined in activity during this period. In the mature, sucrose-accumulating mesocarp, the alkaline form I enzyme was the major ?-galactosidase present. We also observed hydrolysis of raffinose at alkaline conditions in enzyme extracts from other cucurbit sink tissues, as well as from young Coleus blumei leaves. Our results suggest different physiological roles for the ?-galactosidase forms in the developing cucurbit fruit, and show that the newly discovered enzyme plays a physiologically significant role in photoassimilate partitioning in cucurbit sink tissue.

Gao, Zhifang; Schaffer, Arthur A.

1999-01-01

173

Alkaline Phosphatase and Other Hydrolyases Produced by Cenococcum graniforme, an Ectomycorrhizal Fungus  

PubMed Central

Cell extracts of Cenococcum graniforme have been found to contain the following hydrolytic enzymes: protease, esterase, ?-d-galactopyranosidase, ?-d-galactopyranosidase, ?-d-mannopyranosidase, ?-d-xylopyranosidase, ?-d-glucopyranosidase, ?-d-glucopyranosidase, and alkaline phosphatase. Sulfatase, inorganic pyrophosphatase, and ?-d-mannopyranosidase were not detected in the extracts. ?-d-Xylopyranosidase and ?-d-mannopyranosidase were most active in the neutral pH range, protease and phosphatase were most active in the alkaline pH range, and other enzymes were most active in the acidic pH range. These enzymes showed a high association with cell wall material, and the release of enzymes from the cells into the culture fluid appeared to occur only when the cells were undergoing autolysis. Alkaline phosphatase in C. graniforme is a constitutive enzyme, and examination of the alkaline phosphatase following a purification of 265-fold produced the following characteristics: pH optimum of 9.5, Mr of 60,000, Km of 2.1 × 10-4 M for p-nitrophenylphosphate, and activation energy for hydrolysis of the substrate at 9.9 kcal (1 cal = 4.184 J)/mol.

Bae, Kwang-Sung; Barton, Larry L.

1989-01-01

174

Interferences from aldehydes and peroxyacetyl nitrate when sampling urban air organic acids on alkaline traps  

SciTech Connect

The authors have investigated the possible conversion of formaldehyde to formate and of acetaldehyde and peroxyacetyl nitrate (PAN) to acetate when sampling organic acids in urban air using alkaline traps. Tests were carried out with cartridges (C{sub 18} and alumina) and with filters (25 and 47 mm, glass or paper) coated with KOH and carbonate, aldehydes concentrations of 8-240 ppb, PAN concentrations of 50-160 ppb, sampling flow rates of 0.4-15 L/min, and sampling times of 1-24 h, in both purified and particle-free ambient air. Disproportionation of aldehydes to acids was negligible, accounting for 1-3% of the aldehyde concentration irrespective of trap type, aldehyde concentration, sampling flow rate, and test duration. Conversion of PAN to acetate on alkaline traps heterogeneous alkaline hydrolysis was 11-17% for carbonate and KOH filters, 16-27% for carbonate cartridges, and 100% for KOH cartridges. Laboratory tests and analysis of ambient data for three recent southern California field studies both indicate negligible contribution of formaldehyde and acetaldehyde to the formic acid and acetic acid, respectively, measured in alkaline filter and cartridge samples.

Grosjean, D.; Parmar, S.S. (DGA, Inc., Ventura, CA (USA))

1990-07-01

175

Net alkalinity and net acidity 1: Theoretical considerations  

Microsoft Academic Search

Net acidity and net alkalinity are widely used, poorly defined, and commonly misunderstood parameters for the characterization of mine drainage. The authors explain theoretical expressions of 3 types of alkalinity (caustic, phenolphthalein, and total) and acidity (mineral, CO2, and total). Except for rarely-invoked negative alkalinity, theoretically defined total alkalinity is closely analogous to measured alkalinity and presents few practical interpretation

Carl S. Kirby; Charles A. Cravotta

2005-01-01

176

Determination of seston alkalinity in natural waters  

Microsoft Academic Search

Seston alkalinity is a term introduced with the purpose of considering the acid base neutral capacity of the particles integrating it. It can be determined by a simple method, based on a volumetric titration. In alkaline waters, this variable is associated with the insoluble forms of carbonates of the seston.

Victor H. Conzonno; Ciencias Naturales

1991-01-01

177

Titanium corrosion in alkaline hydrogen peroxide environments  

Microsoft Academic Search

The corrosion of Grade 2 titanium in alkaline hydrogen peroxide environments has been studied by weight loss corrosion tests, electrochemical impedance spectroscopy (EIS), linear polarization resistance (LPR) measurements and potentiodynamic polarography. Calcium ions and wood pulp were investigated as corrosion inhibitors. In alkaline peroxide, the titanium corrosion rate increased with increasing pH, temperature, and hydrogen peroxide concentration. The corrosion controlling

Jantje Been

1998-01-01

178

Evaluation of the alkaline electrolysis of zinc  

Microsoft Academic Search

The alkaline leach and electrolysis process for zinc production is compared to the conventional acid-sulfate process in terms of both energy saving and technical merit. In addition, the potential for industrial application of the alkaline process is discussed on the basis of present market conditions, possible future zinc market scenarios, and the probability of increased secondary zinc recovery. In primary

J. H. Meisenhelder; A. P. Brown; R. O. Loutfy; N. P. Yao

1981-01-01

179

Alkalinity changes generated by phytoplankton growth1  

Microsoft Academic Search

Continuous cultures of three marine phytoplankton species, Phaeodactylum tricornutum, Dunaliella tertiolecta, and Monochrysis lutheri, were monitored for changes in alkalinity of the culture medium resulting From NO, and NHa+ uptake. Uptake of NO,- caused an increase in alkalinity, whereas uptake of NH,+ produced a decrease. These results are consistent with the type of schematic equation proposed by Redfield, Ketchum, and

Peter G. Brewer; Joel C. Goldmn

180

A simple spectrophotometric determination of meptyldinocap by its hydrolysis.  

PubMed

A simple spectrophotometric method is proposed for the determination of meptyldinocap (2,4-dinitro-6-octylphenyl crotonate). The method is based on the hydrolysis of meptyldinocap by hydroxylamine solution in alkaline medium to give 2,4-dinitro-6-octylphenol (2,4-DNOP), having maximum absorption at 380 nm. The reaction is found to be instantaneous in presence of ethanol. Beer's law is valid over the concentration range of 1.2-13 microg mL(-1) with molar absorptivity and Sandell's sensitivity of 3.22 x 10(6) L mol(-1) cm(-1) and 0.0001 microg cm(-2) respectively. The limit of detection and quantification were 0.0892 and 0.2703 microg mL(-1), respectively. The tolerance limits of interfering ions are discussed. All variables were studied in order to optimize the reaction conditions. The validity of the method was checked by its simultaneous determination in fruits and water samples and the results were statistically compared with those of a reference method by applying the Student's t-test and F-test. PMID:23841335

Kurup, Sunita; Pillai, Ajai Kumar

2013-01-01

181

Evolution of alkaline phosphatases in primates.  

PubMed Central

Alkaline phosphatase [orthophosphoric-monoester phosphohydrolase (alkaline optimum), EC 3.1.3.1] in placenta, intestine, liver, kidney, bone, and lung from a variety of primate species has been characterized by quantitative inhibition, thermostability, and immunological studies. Characteristic human placental-type alkaline phosphatase occurs in placentas of great apes (chimpanzee and orangutan) but not in placentas of other primates, including gibbon. It is also present in trace amounts in human lung but not in lung or other tissues of various Old and New World monkeys. However, a distinctive alkaline phosphatase resembling it occurs in substantial amounts in lungs from Old World monkeys but not New World monkeys. It appears that duplication of alkaline phosphatase genes and mutations of genetic elements controlling their tissue expression have occurred relatively recently in mammalian evolution. Images

Goldstein, D J; Rogers, C; Harris, H

1982-01-01

182

Anisole hydrolysis in high temperature water.  

PubMed

We investigated the hydrolysis of anisole to phenol in high-temperature water with and without water-tolerant Lewis acid catalysis. With no catalyst present, anisole hydrolyzes to phenol in 97% yield after 24 hours at 365 °C, our experimentally determined optimal temperature and time. Experiments with varied water density and analysis of comparable literature data suggest that anisole hydrolysis is almost third order in water, when the S(N)2 mechanism dominates. Of the water-tolerant Lewis acid catalysts studied, In(OTf)(3) offered the best phenol yield. Anisole hydrolysis was first order in catalyst and first order in substrate. Introducing In(OTf)(3) catalysis lowered the activation energy for anisole hydrolysis to 31 ± 1 kcal mol(-1). Anisole hydrolysis in high-temperature water with In(OTf)(3) catalysis is competitive with other techniques in the literature based on rate and yield. In the presence of 5 mol% In(OTf)(3) catalyst, anisole hydrolyzes to phenol in 97% yield after 90 minutes at 300 °C. PMID:23381061

Rebacz, Natalie A; Savage, Phillip E

2013-02-04

183

Ethanol from biomass by enzymatic hydrolysis  

SciTech Connect

Enzymes are biological catalysts that generally are designed to do one job well, but to do one job only. Therefore, the enzymes that catalyze the hydrolysis of cellulose to sugar do not break down the sugars. Thus, enzymatic processes are capable of yields approaching 100%. Enzymatic hydrolysis processes have been under development for only 10 years. Although improvements have been made in enzymatic technology, more are both possible and necessary. The important research issues include understanding the processes necessary to render the crystalline cellulose easily digestible, understanding and improving the basic mechanisms in the hydrolysis step, and developing better and less expensive enzymes. The hemicellulose fraction (25%) is primarily composed of xylan, which is simple to convert to the simple sugar xylose, but the xylose is difficult to ferment to ethanol. There were no practical systems for xylose fermentation 10 years ago. Today, methods have been identified using new yeasts, fungi, bacteria, and processes combining enzymes and yeasts. Although none of the fermentations is yet ready for commercial use, considerable progress has been made. The following sections describe current research efforts in each of the major areas (cellulose hydrolysis, xylose fermentation, and lignin conversion), with an emphasis on enzymatic hydrolysis using fungal enzymes.

Wright, J.D.

1988-08-01

184

Alkaline assisted thermal oil recovery: Kinetic and displacement studies  

SciTech Connect

This report deals with two major issues of chemical assisted flooding - the interaction of caustic, one of the proposed additives to steam flood, with the reservoir rock, and the displacement of oil by a chemical flood at elevated temperatures. A mathematical model simulating the kinetics of silica dissolution and hydroxyl ion consumption in a typical alkaline flooding environment is first developed. The model is based on the premise that dissolution occurs via hydrolysis of active sites through the formation of an intermediate complex, which is in equilibrium with the silicic acid in solution. Both static (batch) and dynamic (core flood) processes are simulated to examine the sensitivity of caustic consumption and silica dissolution to process parameters, and to determine rates of propagation of pH values. The model presented provides a quantitative description of the quartz-alkali interaction in terms of pH, salinity, ion exchange properties, temperature and contact time, which are of significant importance in the design of soluble silicate flooding processes. The modeling of an adiabatic hot waterflood assisted by the simultaneous injection of a chemical additive is next presented. The model is also applicable to the hot alkaline flooding under conditions of negligible adsorption of the generated anionic surfactant and of hydroxide adsorption being Langmuirian. The theory of generalized simple waves (coherence ) is used to develop solutions for the temperature, concentration, and oil saturation profiles, as well as the oil recovery curves. It is shown that, for Langmuir adsorption kinetics, the chemical resides in the heated region of the reservoir if its injection concentration is below a critical value, and in the unheated region if its concentration exceeds this critical value. Results for a chemical slug injection in a tertiary recovery process indicate recovery performance is maximized when chemical resides in the heated region of the reservior.

Saneie, S.; Yortsos, Y.C.

1993-06-01

185

Migration and hydrolysis of hydrophobic polylactide plasticizer.  

PubMed

Hydrophobic plasticizer protects polylactide (PLA) against hydrolytic degradation but still migrates to aging medium and there undergoes further hydrolysis contributing to the spectrum of degradation products. PLA plasticized with hydrophobic acetyl tributyl citrate (ATC) plasticizer showed a slower degradation rate compared with pure PLA because of the increased hydrophobicity of the material. The enhanced bulk hydrophobicity also overcame the degradation enhancing effect of hydrophilic surface grafting. In addition to plasticization with ATC, some of the samples were also surface grafted with acrylic acid. The materials were subjected to hydrolysis at 37 and 60 degrees C for up to 364 days to compare the effect of hydrophobic and hydrophilic bulk and surface modifications. Although considered insoluble in water, the plasticizer was detected in the water solutions immediately upon immersion of the materials, and the relative abundance of the ATC degradation products increased with hydrolysis time. PMID:19928814

Höglund, Anders; Hakkarainen, Minna; Albertsson, Ann-Christine

2010-01-11

186

Kinetic isotope effects for alkaline phosphatase reactions: implications for the role of active-site metal ions in catalysis.  

PubMed

Enzyme-catalyzed phosphoryl transfer reactions have frequently been suggested to proceed through transition states that are altered from their solution counterparts, with the alterations presumably arising from interactions with active-site functional groups. In particular, the phosphate monoester hydrolysis reaction catalyzed by Escherichia coli alkaline phosphatase (AP) has been the subject of intensive scrutiny. Recent linear free energy relationship (LFER) studies suggest that AP catalyzes phosphate monoester hydrolysis through a loose transition state, similar to that in solution. To gain further insight into the nature of the transition state and active-site interactions, we have determined kinetic isotope effects (KIEs) for AP-catalyzed hydrolysis reactions with several phosphate monoester substrates. The LFER and KIE data together provide a consistent picture for the nature of the transition state for AP-catalyzed phosphate monoester hydrolysis and support previous models suggesting that the enzymatic transition state is similar to that in solution. Moreover, the KIE data provides unique information regarding specific interactions between the transition state and the active-site Zn2+ ions. These results provide strong support for a model in which electrostatic interactions between the bimetallo Zn2+ site and a nonbridging phosphate ester oxygen atom make a significant contribution to the large rate enhancement observed for AP-catalyzed phosphate monoester hydrolysis. PMID:17630738

Zalatan, Jesse G; Catrina, Irina; Mitchell, Rebecca; Grzyska, Piotr K; O'brien, Patrick J; Herschlag, Daniel; Hengge, Alvan C

2007-07-14

187

Acid hydrolysis of hemicellulose in green liquor pre-pulping extract of mixed northern hardwoods.  

PubMed

Forest biomass is a promising resource for future biofuels and bioproducts. Pre-pulping extraction of hemicellulose by alkaline (Green Liquor) pretreatment produces a neutral-pH extract containing hemicellulose-derived oligomers. A near-term option for use of this extract is to hydrolyze the oligomers to fermentable monomer sugars. Chips of mixed northern hardwoods were cooked in a rocking digester at 160 degrees C for 110 min in Green Liquor at a concentration of 3% Na2O equivalent salts on dry wood. The mass of wood extracted into the Green Liquor extract was approximately 11.4% of the debarked wood mass, which resulted in a dilute solution of oligomeric hemicelluloses sugars. The concentration of the extract was increased through partial evaporation prior to hydrolysis. Dilute sulfuric acid hydrolysis was applied at conditions ranging from 100 to 160 degrees C, 2% to 6% (w/v) H2SO4, and 2- to 258-min residence time. The maximum fermentable sugar concentration achieved from evaporated extract was 10.7 g/L, representing 90.7% of the maximum possible yield. Application of the biomass pretreatment severity function to the hydrolysis results proved to offer a relatively poor prediction of temperature and reaction time interaction. The combined severity function, which incorporates reaction time, temperature, and acid concentration, did prove to provide a useful means of trading off the combined effects of these three variables on total sugar yields. PMID:19337862

Um, Byung-Hwan; van Walsum, G Peter

2009-04-01

188

[Degradation of nicosulfuron by combination effects of microorganisms and chemical hydrolysis].  

PubMed

A strain which was capable of degrading nicosulfuron in the presence of glucose was isolated from nicosulfuron contaminated wetland soil, and it was identified as Klebsiella sp. based on 16S rDNA gene sequencing analysis. The strain could grow using nicosulfuron as the sole nitrogen source. The optimal temperature was 35 degrees C and the initial pH was neutral to weak acid. Hydrolysis experiments indicated that nicosulfuron remained stably under neutral and alkaline conditions, while in acidic conditions, it hydrolyzed quickly. Based on biodegradation experiments, when the concentration of glucose in culture was 5 g x L(-1), the strain could degrade 99.4% of nicosulfuron after incubation for 10 days at 35 degrees C, initial pH = 7; pH of the solution decreased from initial 7.0 to 4.0 in the meantime. When the concentration of glucose in culture solution was decreased to 500 mg x L(-1) and 100 mg x L(-1), with other conditions unchanged, only 11.7% and 6.6% of nicosulfuron were degraded, respectively, and pH of the solution remained at around 7.0. It was proposed that the degradation of nicosulfuron was caused by hydrolysis under acidic conditions at low pH which was resulted from the biodegradation of glucose by the strain. Therefore, the removal of nicosulfuron was actually caused by combined effects of microorganisms and chemical hydrolysis. PMID:24028028

Zhang, Xiao-Lin; Li, Yong-Mei; Yuan, Zhi-Wen

2013-07-01

189

Hydrolysis of iodine: equilibria at high temperatures  

SciTech Connect

The hydrolysis (or disproportionation) of molecular iodine to form iodate and iodide ions has been studied by emf measurements over the temperature range, 3.8/sup 0/ to 209.0/sup 0/C. The interpretation of these results required a knowledge of the formation constant for triiodide ion and the acid dissociation constant of iodic acid, both of which were measured as a function of temperature. The resulting thermodynamic data have been incorporated into a general computer model describing the hydrolysis equilibria of iodine as a function of initial concentration, pH and temperature.

Palmer, D.A.; Ramette, R.W.; Mesmer, R.E.

1984-01-01

190

Alkaline solution neutralization capacity of soil.  

PubMed

Alkaline eluate from municipal solid waste (MSW) incineration residue deposited in landfill alkalizes waste and soil layers. From the viewpoint of accelerating stability and preventing heavy metal elution, pH of the landfill layer (waste and daily cover soil) should be controlled. On the other hand, pH of leachate from existing MSW landfill sites is usually approximately neutral. One of the reasons is that daily cover soil can neutralize alkaline solution containing Ca(2+) as cation. However, in landfill layer where various types of wastes and reactions should be taken into consideration, the ability to neutralize alkaline solutions other than Ca(OH)(2) by soil should be evaluated. In this study, the neutralization capacities of various types of soils were measured using Ca(OH)(2) and NaOH solutions. Each soil used in this study showed approximately the same capacity to neutralize both alkaline solutions of Ca(OH)(2) and NaOH. The cation exchange capacity was less than 30% of the maximum alkali neutralization capacity obtained by the titration test. The mechanism of neutralization by the pH-dependent charge can explain the same neutralization capacities of the soils. Although further investigation on the neutralization capacity of the soils for alkaline substances other than NaOH is required, daily cover soil could serve as a buffer zone for alkaline leachates containing Ca(OH)(2) or other alkaline substances. PMID:20395123

Asakura, Hiroshi; Sakanakura, Hirofumi; Matsuto, Toshihiko

2010-04-14

191

Alkaline sorbent injection for mercury control  

DOEpatents

A mercury removal system for removing mercury from combustion flue gases is provided in which alkaline sorbents at generally extremely low stoichiometric molar ratios of alkaline earth or an alkali metal to sulfur of less than 1.0 are injected into a power plant system at one or more locations to remove at least between about 40% and 60% of the mercury content from combustion flue gases. Small amounts of alkaline sorbents are injected into the flue gas stream at a relatively low rate. A particulate filter is used to remove mercury-containing particles downstream of each injection point used in the power plant system.

Madden, Deborah A. (Boardman, OH); Holmes, Michael J. (Washington Township, Stark County, OH)

2003-01-01

192

Alkaline sorbent injection for mercury control  

DOEpatents

A mercury removal system for removing mercury from combustion flue gases is provided in which alkaline sorbents at generally extremely low stoichiometric molar ratios of alkaline earth or an alkali metal to sulfur of less than 1.0 are injected into a power plant system at one or more locations to remove at least between about 40% and 60% of the mercury content from combustion flue gases. Small amounts of alkaline sorbents are injected into the flue gas stream at a relatively low rate. A particulate filter is used to remove mercury-containing particles downstream of each injection point used in the power plant system.

Madden, Deborah A. (Boardman, OH); Holmes, Michael J. (Washington Township, Stark County, OH)

2002-01-01

193

Process for extracting technetium from alkaline solutions  

DOEpatents

A process for extracting technetium values from an aqueous alkaline solution containing at least one alkali metal hydroxide and at least one alkali metal nitrate, the at least one alkali metal nitrate having a concentration of from about 0.1 to 6 molar. The solution is contacted with a solvent consisting of a crown ether in a diluent for a period of time sufficient to selectively extract the technetium values from the aqueous alkaline solution. The solvent containing the technetium values is separated from the aqueous alkaline solution and the technetium values are stripped from the solvent.

Moyer, Bruce A. (Oak Ridge, TN); Sachleben, Richard A. (Knoxville, TN); Bonnesen, Peter V. (Knoxville, TN)

1995-01-01

194

Microstructure of coke briquettes from hydrolysis lignin  

Microsoft Academic Search

The microstructure of pyrolyzed briquettes prepared from hydrolyzed lignins at different final heating temperatures has been investigated. The pore structure of the briquettes of hydrolysis lignins before the thermal treatment is dependent to a large extent upon the granulometric composition of the raw material. The initial structure of the lignins also played an important part on the effect of the

B. N. Zhitov; Yu. G. Korolev; G. N. Makarov; A. M. Myasoedov; I. A. Shimanskaya; V. P. Okladnikov

1984-01-01

195

Lipase-mediated hydrolysis of blackcurrant oil.  

PubMed

Four commercially available lipases, both free and immobilized, were tested for their ability to catalyze hydrolysis of blackcurrant (Ribes nigrum) oil using two different approaches. The lipase from Mucor miehei was studied free and immobilized in two different ways. The former series of enzymic reactions were performed in tap water at 40 degrees C, but the latter series of enzymic processes were carried out in mixtures of isooctane and phosphate buffer (in a typical 2/1 ratio of the components) at 30 degrees C. These conditions were optimized to increase and/or to maximize the yields of the products, which were priority targets in this study. A rate of hydrolysis and a selective preference of the hydrolytic enzymes towards fatty acids, with a special focus on enrichment of alpha-linolenic acid and/or gamma-linolenic acid, were studied. Higher rates of hydrolysis of the blackcurrant oil in the former series of reactions were observed with the immobilized lipase from Pseudomonas cepacia used as biocatalyst. In the latter approach, the most favorable results of the rate of hydrolysis of the target blackcurrant oil were achieved with the immobilized lipase from Mucor miehei employed as biocatalyst. Only three lipases, selected from a series of lipases tested during this investigation, displayed specificity towards alpha-linolenic acid and gamma-linolenic acid, i.e. the immobilized lipase from P. cepacia, lipase from M. miehei and lipase from P. fluorescens. PMID:10978776

Vacek; Zarevúcka; Wimmerb; Stránský; Koutek; Macková; Demnerová

2000-10-01

196

Storage oil hydrolysis during early seedling growth  

Microsoft Academic Search

Storage oil breakdown plays an important role in the life cycle of many plants by providing the carbon skeletons that support seedling growth immediately following germination. This metabolic process is initiated by lipases (EC: 3.1.1.3), which catalyze the hydrolysis of triacylglycerols (TAGs) to release free fatty acids and glycerol. A number of lipases have been purified to near homogeneity from

Anne-Laure Quettier; Peter J. Eastmond

2009-01-01

197

Interfacial charge effects during natural oil hydrolysis  

Microsoft Academic Search

This paper describes a novel laboratory scale catalytic bioreactor for the hydrolysis of natural oils in the presence of free lipase. The novelty of the reactor system is that it uses an electrostatic dispersion technique to both control the interfacial area available for the reaction and improve on the quality of that area. The system is shown to produce higher

L. R. Weatherley; D. W. Rooney; M. V. Niekerk

1997-01-01

198

Siloxanes from the hydrolysis of isopropyltrimethoxysilane  

Microsoft Academic Search

The behavior of isopropyltrimethoxysilane (1 in the presence one equivalent of water and a dibutyltin dilaurate catalyst has been investigated. Under these conditions, partial hydrolysis of the methoxy groups of 1 occurred, followed by condensation reactions leading to the formation of low molecular-weight oligomers. Disiloxane 4, trisiloxane 6 and cyclic siloxane 7 and 8 have been isolated and fully characterized.

Jack K. Crandall; Christophe Morel-Fourrier

1995-01-01

199

HD Hydrolysis/Biodegradation Toxicology and Kinetics.  

National Technical Information Service (NTIS)

One technology developed for potential use in the disposal of RD (2,2'-dichlorodiethyl sulfide) from the Aberdeen Proving Ground unitary chemical stockpile is hydrolysis followed by biodegradation. Stockpile RD (89.2% pure) was hydrolyzed in 90 deg C wate...

S. P. Harvey L. L. Szafraniec W. T. Beaudry M. V. Haley T. E. Rosso

1996-01-01

200

COMPUTERIZED EXTRAPOLATION OF HYDROLYSIS RATE DATA  

EPA Science Inventory

The program RATE was developed to aid in the extrapolation and interpretation of hydrolysis rate data to a format that is useful for environmental risk assessment. ydrolysis data typically are reported in the literature as pseudo-first-order rate constants at the temperature and ...

201

Alkaline Lixiviation of Uranium in Granitic Pegmatite.  

National Technical Information Service (NTIS)

The work described herein concerns the determination of the experimental optimum conditions for the alkaline lixiviation of uranium based on the following parameters: time, pH, temperature, density and grain size. The samples were obtained from the Supamo...

S. Jambor

1980-01-01

202

Evaluation of the alkaline electrolysis of zinc  

SciTech Connect

The alkaline leach and electrolysis process for zinc production is compared to the conventional acid-sulfate process in terms of both energy saving and technical merit. In addition, the potential for industrial application of the alkaline process is discussed on the basis of present market conditions, possible future zinc market scenarios, and the probability of increased secondary zinc recovery. In primary zinc production, the energy-saving potential for the alkaline process was estimated to be greater than 10%, even when significantly larger electrolysis current densities than those required for the sulfate process are used. The principal technical advantages of the alkaline process are that it can handle low-grade, high-iron-content or oxidized ores (like most of those found in the US) in a more cost- and energy-efficient manner than can the sulfate process. Additionally, in the electrowinning operation, the alkaline process should be technically superior because a dendritic or sponge deposit is formed that is amenable to automated collection without interruption of the electrolysis. Also, use of the higher current densities would result in significant capital cost reductions. Alkaline-based electrolytic recovery processes were considered for the recycling of zinc from smelter baghouse dusts and from the potential source of nickel/zinc electric-vehicle batteries. In all comparisons, an alkaline process was shown to be technically superior and, particularly for the baghouse dusts, energetically and economically superior to alternatively proposed recovery methods based on sulfate electrolysis. It is concluded that the alkaline zinc method is an important alternative technology to the conventional acid zinc process. (WHK)

Meisenhelder, J.H.; Brown, A.P.; Loutfy, R.O.; Yao, N.P.

1981-05-01

203

Toxicity of alkalinity to Hyalella azteca  

USGS Publications Warehouse

Toxicity testing and chemical analyses of sediment pore water have been suggested for use in sediment quality assessments and sediment toxicity identification evaluations. However, caution should be exercised in interpreting pore-water chemistry and toxicity due to inherent chemical characteristics and confounding relationships. High concentrations of alkalinity, which are typical of sediment pore waters from many regions, have been shown to be toxic to test animals. A series of tests were conducted to assess the significance of elevated alkalinity concentrations to Hyalella azteca, an amphipod commonly used for sediment and pore-water toxicity testing. Toxicity tests with 14-d old and 7-d old animals were conducted in serial dilutions of sodium bicarbonate (NaHCO3) solutions producing alkalinities ranging between 250 to 2000 mg/L as CaCO3. A sodium chloride (NaCl) toxicity test was also conducted to verify that toxicity was due to bicarbonate and not sodium. Alkalinity was toxic at concentrations frequently encountered in sediment pore water. There was also a significant difference in the toxicity of alkalinity between 14-d old and 7-d old animals. The average 96-h LC50 for alkalinity was 1212 mg/L (as CaCO3) for 14-d old animals and 662 mg/L for the younger animals. Sodium was not toxic at levels present in the NaHCO3 toxicity tests. Alkalinity should be routinely measured in pore-water toxicity tests, and interpretation of toxicity should consider alkalinity concentration and test-organism tolerance.

Lasier, P.J.; Winger, P.V.; Reinert, R.E.

1997-01-01

204

Alkaline tolerant dextranase from streptomyces anulatus  

DOEpatents

A process for production of an alkaline tolerant dextranase enzyme comprises culturing a dextran-producing microorganism Streptomyces anulatus having accession no. ATCC PTA-3866 to produce an alkaline tolerant dextranase, Dex 1 wherein the protein in said enzyme is characterized by a MW of 63.3 kDa and Dex 2 wherein its protein is characterized by a MW of 81.8 kDa.

Decker, Stephen R. (Berthoud, CO); Adney, William S. (Golden, CO); Vinzant, Todd B. (Golden, CO); Himmel, Michael E. (Littleton, CO)

2003-01-01

205

Non-catalytic steam hydrolysis of fats  

SciTech Connect

Hydrolysis of fats and oils produces fatty acid and glycerol. The catalyzed, liquid phase Colgate-Emry process, state-of-the-art, produces impure products that require extensive energy investment for their purification to commercial grade. Non-catalytic steam hydrolysis may produce products more easily purified. A bench-scale hydrolyzer was designed and constructed to contact descending liquid fat or oil with rising superheated steam. Each of the five stages in the reactor was designed similar to a distillation column stage to promote intimate liquid-gas contact. Degree of hydrolysis achieved in continuous tests using tallow feed were 15% at 280C and 35% at 300C at a tallow-to-steam mass feed ratio of 4.2. At a feed ratio of 9.2, the degree of hydrolysis was 21% at 300C. Decomposition was strongly evident at 325C but not at lower temperatures. Soybean oil rapidly polymerized under reaction conditions. Batch tests at 320C produced degrees of hydrolyses of between 44% and 63% using tallow and palm oil feeds. Over 95% fatty acids were present in a clean, readily separated organic portion of the overhead product from most tests. The test reactor had serious hydraulic resistance to liquid down-flow which limited operation to very long liquid residence times. These times are in excess of those that tallow and palm oil are stable at the reaction temperature. Little glycerol and extensive light organics were produced indicating that unexplained competing reactions to hydrolysis occurred in the experimental system. Further tests using an improved reactor will be required.

Deibert, M.C.

1992-08-28

206

Design and Parametric Evaluation of an Enzymatic Hydrolysis Process (Separate Hydrolysis and Fermentation).  

National Technical Information Service (NTIS)

A separate fungal enzyme hydrolysis and fermentation process for converting lignocellulose to ethanol was evaluated. Although the current state-of-the-art process is expensive, research now under way has the potential to reduce projected selling prices by...

J. D. Wright A. J. Power L. J. Douglas

1986-01-01

207

The influence of alkaline and non-alkaline parent material on soil chemistry  

Microsoft Academic Search

The gneiss bedrock of Alnö Island, situated at the eastern coastline of central Sweden (62°24?N, 17°30?E), has alkaline intrusions interspersed in narrow dikes. This gives the opportunity to create experimental designs, where the impact of different parent material on the soil solution chemistry can be exclusively investigated.In this study, three alkaline sites and three non-alkaline sites were mineralogically identified within

Jenny L. K. Vestin; Kei Nambu; Patrick A. W. van Hees; Dan Bylund; Ulla S. Lundström

2006-01-01

208

Hydrolysis Study and Exposure Data on Trimethyl Phosphate Site.  

National Technical Information Service (NTIS)

As requested in Mr. F. D. Kovar's letter of September 23, 1981, we are enclosing information on trimethyl phosphite hydrolysis and on levels of trimethyl phosphate measured at our production site. Attachment No. 1 summarizes the hydrolysis studies. The da...

1981-01-01

209

Performed surfactant-optimized aqueous alkaline flood  

SciTech Connect

This paper describes improvement in a process for recovering oil from an acidic oil reservoir by injecting an aqueous alkaline solution comprising water, sodium chloride, and alkaline material for reacting with the reservoir oil forming a petroleum acid soap to form an in-situ surfactant system. The improvement comprises: selecting a preformed cosurfactant which is soluble in both the aqueous solution and the reservoir oil and has a solubility ratio which is grater than the solubility ratio of the petroleum acid soap where the solubility ratio is the ratio of solubility in the aqueous alkaline solution to the solubility in the reservoir oil; combining with the alkaline solution an amount of the preformed cosurfactant which will result in the in-situ surfacant system having a salinity about equal to a salinity which results in minimal interfacial tension between the oil in the reservoir and the in-situ surfactant system at reservoir temperature, wherein the amount of the preformed cosurfactant is about 0.3 percent by weight in the aqueous alkaline solution; and injecting the cosurfactant-aqueous alkaline solution mixture into the reservoir to displace oil toward a fluid production location.

Thigpen, D.R.; Lawson, J.B.; Nelson, R.C.

1991-11-26

210

Column cellulose hydrolysis reactor: An efficient cellulose hydrolysis reactor with continuous cellulase recycling  

Microsoft Academic Search

The use of a column cellulose hydrolysis reactor with continuous enzyme recycling was demonstrated by incorporating a continuous ultrafiltration apparatus at the effluent end of the column reactor. Using this setup, over 90% (w\\/v) cellulose hydrolysis was achieved, resulting in an average sugar concentration of 6.8% (w\\/v) in the effluent stream. The output of the system was 1.98 g of

Larry U. L. Tan; Ernest K. C. Yu; Nancy Campbell; John N. Saddler

1986-01-01

211

Muscarinic receptor activation of phosphatidylcholine hydrolysis. Relationship to phosphoinositide hydrolysis and diacylglycerol metabolism  

Microsoft Academic Search

We examined the relationship between phosphatidylcholine (PC) hydrolysis, phosphoinositide hydrolysis, and diacylglycerol (DAG) formation in response to muscarinic acetylcholine receptor (mAChR) stimulation in 1321N1 astrocytoma cells. Carbachol increases the release of (3H)choline and (3H)phosphorylcholine ((3H)Pchol) from cells containing (3H)choline-labeled PC. The production of Pchol is rapid and transient, while choline production continues for at least 30 min. mAChR-stimulated release of

E. A. Martinson; D. Goldstein; J. H. Brown

1989-01-01

212

Removing Hemicellulose from Pulps by Specific Enzymic Hydrolysis  

Microsoft Academic Search

The hemicellulose content (solubility in 18% NaOH) of a delignified mechanical aspen pulp was lowered from 23.4% to 18.2% by one-hour hydrolysis with xylanase isolated from the fungus Schizophpllum commune by fractional precipitation. After 24 h hydrolysis, the hemicellulose content was reduced further to 12.9%. The predominant hydrolysis products, xylose and xylobiose, confirmed the specificity of hydrolysis. A crude mixture

M. G. Paice; L. Jurasek

1984-01-01

213

Hydrolysis and oxidation of gaseous HCN over heterogeneous catalysts  

Microsoft Academic Search

The hydrolysis and oxidation of HCN, which is a potential toxic emission of automotive catalysts, were systematically examined with model gas experiments on typical hydrolysis, SCR and oxidation catalysts.TiO2-anatase showed the highest HCN hydrolysis activity among the hydrolysis catalysts, with approximately two times more activity than Al2O3. On Fe-ZSM-5, HCN was converted to NH3 to the same degree as on

O. Kröcher; M. Elsener

2009-01-01

214

Detection of the sarin hydrolysis product in formalin-fixed brain tissues of victims of the Tokyo subway terrorist attack.  

PubMed

One of the hydrolysis products of sarin (isopropyl methylphosphonofluoridate) was detected in formalin-fixed brain tissues of victims poisoned in the Tokyo subway terrorist attack. Part of this procedure, used for the detection of sarin hydrolysis products in erythrocytes of sarin victims, has been described previously. The test materials were four individual cerebellums, which had been stored in formalin fixative for about 2 years. Sarin-bound acetylcholinesterase (AChE) was solubilized from these cerebellums, purified by immunoaffinity chromatography, and digested with trypsin. Then the sarin hydrolysis products bound to AChE were released by alkaline phosphatase digestion, subjected to trimethylsilyl derivatization (TMS), and detected by gas chromatography-mass spectrometry. Peaks at m/z 225 and m/z 240, which are indicative of TMS-methylphosphonic acid, were observed within the retention time range of authentic methylphosphonic acid. However, no isopropyl methylphosphonic acid was detected in the formalin-fixed cerebellums of these 4 sarin victims, probably because the isopropoxy group of isopropyl methylphosphonic acid underwent chemical hydrolysis during storage. This procedure will be useful for the forensic diagnosis of poisoning by protein-bound, highly toxic agents, such as sarin, which are easily hydrolysed. This appears to be the first time that intoxication by a nerve agent has been demonstrated by analyzing formalin-fixed brains obtained at autopsy. PMID:9653062

Matsuda, Y; Nagao, M; Takatori, T; Niijima, H; Nakajima, M; Iwase, H; Kobayashi, M; Iwadate, K

1998-06-01

215

Enzymatic hydrolysis of castor oil: Process intensification studies  

Microsoft Academic Search

The usual methods of castor oil hydrolysis give impure product, i.e. ricinoleic acid. An alternative technique for production is the enzymatic hydrolysis of castor oil where the product is available as a light colored and odorless product. Usually lipase catalyzed enzymatic hydrolysis has been carried out in oil in water emulsions, which require rather high quantities of enzymes limiting the

Meenal S. Puthli; Virendra K. Rathod; Aniruddha B. Pandit

2006-01-01

216

A review: Hydrogen generation from borohydride hydrolysis reaction  

Microsoft Academic Search

In this review, a convenient hydrogen generation technology based on sodium borohydride and water as hydrogen carriers has been summarized. The recent progresses in the development of the hydrogen generation from sodium borohydride hydrolysis are reviewed. The NaBH4 hydrolysis behavior is discussed in detail. From reported results, it is considered that hydrogen generation from sodium borohydride hydrolysis is a feasible

B. H. Liu; Z. P. Li

2009-01-01

217

Technical bases for precipitate hydrolysis process operating parameters  

SciTech Connect

This report provides the experimental data and rationale in support of the operating parameters for precipitate hydrolysis specified in WSRC-RP-92737. The report is divided into two sections, the first dealing with lab-scale precipitate hydrolysis experimentation while the second part addresses large-scale runs conducted to demonstrate the revised operating parameters in the Precipitate Hydrolysis Experimental Facility (PHEF).

Bannochie, C.J.

1992-10-05

218

Alkaline Injection for Enhanced Oil Recovery - A Status Report  

Microsoft Academic Search

In the past several years, there has been renewed interest in enhanced oil recovery (EOR) by alkaline injection. Alkaline solutions also are being used as preflushes in micellar\\/polymer projects. Several major field tests of alkaline flooding are planned, are in progress, or recently have been completed. Considerable basic research on alkaline injection has been published recently, and more is in

E. H. Mayer; R. L. Berg; J. D. Carmichael; R. M. Weinbrandt

1983-01-01

219

Recovery of chromium(III) from wastes of uncolored chromium leathers. Part II. Solvent extraction of chromium(III) from alkaline protein hydrolyzate  

Microsoft Academic Search

Experimental studies were made on the solvent extraction of chromium(III) with Aliquat 336 from the protein hydrolyzate obtained by the alkaline hydrolysis of wastes of uncolored chromium-tanned leathers. The effects of NaOH concentration in the protein hydrolyzate, contact time of the organic and aqueous phases, the aqueous\\/organic phase volume ratio, and temperature on the extraction of chromium(III) and collagen proteins\\/peptides

Barbara Wionczyk; Wies?aw Apostoluk; Witold A. Charewicz; Zbigniew Adamski

2011-01-01

220

Surfactant-Enhanced Alkaline Flooding: Buffering at Intermediate Alkaline pH  

Microsoft Academic Search

The alkaline flooding process involves injecting alkaline agents into the reservoir to produce more oil than is produced through conventional waterflooding. The interaction of the alkali in the flood water with the naturally occurring acids in the reservoir oil results in in-situ formation of soaps, which are partially responsible for lowering IFT and improving oil recovery. The extent to which

Rudin Jeff; Darsh Wasan

1993-01-01

221

Uptake of arsenic by alkaline soils near alkaline coal fly ash disposal facilities.  

PubMed

The attenuation of arsenic in groundwater near alkaline coal fly ash disposal facilities was evaluated by determining the uptake of arsenic from ash leachates by surrounding alkaline soils. Ten different alkaline soils near a retired coal fly ash impoundment were used in this study with pH ranging from 7.6 to 9.0, while representative coal fly ash samples from two different locations in the coal fly ash impoundment were used to produce two alkaline ash leachates with pH 7.4 and 8.2. The arsenic found in the ash leachates was present as arsenate [As(V)]. Adsorption isotherm experiments were carried out to determine the adsorption parameters required for predicting the uptake of arsenic from the ash leachates. For all soils and leachates, the adsorption of arsenic followed the Langmuir and Freundlich equations, indicative of the favorable adsorption of arsenic from leachates onto all soils. The uptake of arsenic was evaluated as a function of ash leachate characteristics and the soil components. The uptake of arsenic from alkaline ash leachates, which occurred mainly as calcium hydrogen arsenate, increased with increasing clay fraction of soil and with increasing soil organic matter of the alkaline soils. Appreciable uptake of arsenic from alkaline ash leachates with different pH and arsenic concentration was observed for the alkaline soils, thus attenuating the contamination of groundwater downstream of the retired coal fly ash impoundment. PMID:23877575

Khodadoust, Amid P; Theis, Thomas L; Murarka, Ishwar P; Naithani, Pratibha; Babaeivelni, Kamel

2013-07-23

222

Hydrolysis of carbonyl sulfide over alumina  

SciTech Connect

The reaction rate for the hydrolysis of carbonyl sulfide in liquid petroleum hydrocarbons over alumina, such as propylene, is greatly increased by maintaining water in the hydrocarbons in an amount of one mole of water per mole of carbonyl sulfide to an upper limit of about ten moles of water per mole of carbonyl sulfide or about 30% of saturation of the hydrocarbons, whichever upper limit provides the lesser amount of water.

Polleck, R. E.; Ledley, R. E.; Scott, K. A.

1985-01-01

223

?-cyclodextrin assistant flavonoid glycosides enzymatic hydrolysis  

PubMed Central

Background: The content of icaritin and genistein in herba is very low, preparation with relatively large quantities is an important issue for extensive pharmacological studies. Objective: This study focuses on preparing and enzymic hydrolysis of flavonoid glycosides /?-cyclodextrin inclusion complex to increase the hydrolysis rate. Materials and Methods: The physical property of newly prepared inclusion complex was tested by differential scanning calorimetry (DSC). The conditions of enzymatic hydrolysis were optimized for the bioconversion of flavonoid glycosides /?-cyclodextrin inclusion complex by mono-factor experimental design. The experiments are using the icariin and genistein as the model drugs. Results: The solubility of icariin and genistein were increased almost 17 times from 29.2 ?g/ml to 513.5 ?g/ml at 60°C and 28 times from 7.78 ?g/ml to 221.46 ?g/ml at 50°C, respectively, demonstrating that the inclusion complex could significantly increase the solubility of flavonoid glycosides. Under the optimal conditions, the reaction time of icariin and genistin decreased by 68% and 145%, when compared with that without ?-CD inclusion. By using this enzymatic condition, 473 mg icaritin (with the purity of 99.34%) and 567 mg genistein(with the purity of 99.46%), which was finally determined by melt point, ESI-MS, UV, IR, 1H NMR and 13C NMR, was obtained eventually by transforming the inclusion complex(contains 1.0 g substrates). Conclusion: This study can clearly indicate a new attempt to improve the speed of enzyme-hydrolysis of poorly water-soluble flavonoid glycosides and find a more superior condition which is used to prepare icaritin and genistein.

Jin, Xin; Zhang, Zhen-hai; Sun, E.; Jia, Xiao-Bin

2013-01-01

224

Enzymatic Hydrolysis of Cellulose in NMMO  

Microsoft Academic Search

In-situ hydrolysis of de-lignified cellulose pulp dissolved in N-methyl morpholine oxide (NMMO) by commercially available AccelleraseTM1000 was studied under various reaction conditions and reaction schemes. The yield of reducing sugars was followed as a function of time at different cellulose loadings predominantly at an enzyme loading of 122 FPU\\/g and a temperature of 50oC. A twin screw reactor was successfully

Brett S. Robbins

2010-01-01

225

Role of nucleotide hydrolysis in microtubule assembly  

Microsoft Academic Search

MICROTUBULE assembly in vitro requires (in normal conditions) that GTP be bound to the exchangeable nucleotide-binding site of tubulin1-3. The bound GTP is hydrolysed during polymerisation and the resulting GDP remains bound to the microtubule while the phosphate is released into the medium. Although hydrolysis normally occurs during polymerisation, microtubules will form in a non-hydrolysable analogue of GTP, guanylyl imidodiphosphate

R. C. Weisenberg; W. J. Deery

1976-01-01

226

Palm Date Fibers: Analysis and Enzymatic Hydrolysis  

PubMed Central

Waste palm dates were subjected to analysis for composition and enzymatic hydrolysis of their flesh fibers. The fruit contained 32% glucose and 30% fructose, while the water-insoluble fibers of its flesh consisted of 49.9% lignin and 20.9% polysaccharides. Water-insoluble fibers were settled to 55% of its initial volume in 12 h. The presence of skin and flesh colloidal fibers results in high viscosity and clogging problems during industrial processes. The settling velocity of the fibers was improved by enzymatic hydrolysis. Hydrolysis resulted in 84.3% conversion of the cellulosic part of the fibers as well as reducing the settling time to 10 minutes and the final settled volume to 4% of the initial volume. It implies easier separation of the fibers and facilitates fermentation processes in the corresponding industries. Two kinds of high- and low-lignin fibers were identified from the water-insoluble fibers. The high-lignin fibers (75% lignin) settled easily, while the low-lignin fibers (41.4% lignin) formed a slurry suspension which settled very slowly. The hydrophilicity of these low-lignin fibers is the major challenge of the industrial processes.

Shafiei, Marzieh; Karimi, Keikhosro; Taherzadeh, Mohammad J.

2010-01-01

227

Thiogalactopyranosides are resistant to hydrolysis by ?-galactosidases.  

PubMed

Fluorescently tagged glycosides containing terminal ?(1?3) and ?(1?4)-linked thiogalactopyranosides have been prepared and tested for resistance to hydrolysis by ?-galactosidases. Eight fluorescent glycosides containing either galactose or 5-thiogalactose as the terminal sugar were enzymatically synthesized using galactosyltransferases, with lactosyl glycosides as acceptors and UDP-galactose or UDP-5'-thiogalactose, respectively, as donors. The glycosides were incubated with human ?-galactosidase A (CAZy family GH27, a retaining glycosidase), Bacteroides fragilis ?-1,3-galactosidase (GH110, an inverting glycosidase), or homogenates of MCF-7 human breast cancer cells or NG108-15 rat glioma cells. Substrate hydrolysis was monitored by capillary electrophoresis with fluorescence detection. All compounds containing terminal O-galactose were readily degraded. Their 5-thiogalactose counterparts were resistant to hydrolysis by human ?-galactosidase A and the enzymes present in the cell extracts. B. fragilis ?-1,3-galactosidase hydrolyzed both thio- and O-galactoside substrates; however, the thiogalactosides were hydrolyzed at only 1-3 % of the rate of O-galactosides. The hydrolytic resistance of 5-thiogalactose was also confirmed by an in vivo study using cells in culture. The results suggest that 5-thiogalactosides may be useful tools for the study of anabolic pathways in cell extracts or in single cells. PMID:22740420

Adlercreutz, Dietlind; Yoshimura, Yayoi; Mannerstedt, Karin; Wakarchuk, Warren W; Bennett, Eric P; Dovichi, Norman J; Hindsgaul, Ole; Palcic, Monica M

2012-06-27

228

Sugarcane bagasse hydrolysis using yeast cellulolytic enzymes.  

PubMed

Ethanol fuel production from lignocellulosic biomass is emerging as one of the most important technologies for sustainable development. To use this biomass, it is necessary to circumvent the physical and chemical barriers presented by the cohesive combination of the main biomass components, which hinders the hydrolysis of cellulose and hemicellulose into fermentable sugars. This study evaluated the hydrolytic capacity of enzymes produced by yeasts, isolated from the soils of the Brazilian Cerrado biome (savannah) and the Amazon region, on sugarcane bagasse pre-treated with H2SO4. Among the 103 and 214 yeast isolates from the Minas Gerais Cerrado and the Amazon regions, 18 (17.47%) and 11 (5.14%) isolates, respectively, were cellulase-producing. Cryptococcus laurentii was prevalent and produced significant ?- glucosidase levels, which were higher than the endo- and exoglucanase activities. In natura sugarcane bagasse was pre-treated with 2% H2SO4 for 30 min at 150oC. Subsequently, the obtained fibrous residue was subjected to hydrolysis using the Cryptococcus laurentii yeast enzyme extract for 72 h. This enzyme extract promoted the conversion of approximately 32% of the cellulose, of which 2.4% was glucose, after the enzymatic hydrolysis reaction, suggesting that C. laurentii is a good ?-glucosidase producer. The results presented in this study highlight the importance of isolating microbial strains that produce enzymes of biotechnological interest, given their extensive application in biofuel production. PMID:23851270

Souza, Angelica Cristina de; Carvalho, Fernanda Paula; Silva E Batista, Cristina Ferreira; Schwan, Rosane Freitas; Dias, Disney Ribeiro

2013-10-28

229

Hydrolysis of sulphonamides in aqueous solutions.  

PubMed

Hydrolysis is one of the most common reactions controlling abiotic degradation and is one of the main paths by which substances are degraded in the environment. Nevertheless, the available information on this process for many compounds, including sulphonamides (a group of antibiotic drugs widely used in veterinary medicine), is very limited. This is the first study investigating the hydrolytic stabilities of 12 sulphonamides, which were determined according to OECD guideline 111 (1st category reliability data on the basis of regulatory demands on data quality for the environmental risk assessment of pharmaceuticals). Hydrolysis behaviour was examined at pH values normally found in the environment. This was prefaced by a discussion of the acid-base properties of sulphonamides. All the sulphonamides tested were hydrolytically stable at pH 9.0, nine (apart from sulphadiazine, sulphachloropyridazine and sulphamethoxypyridazine) were stable in this respect at pH 7.0 and two (sulphadiazine and sulphaguanidine) at pH 4.0 (hydrolysis rate?10%; t(0.5 (25°C))>1 year). The degradation products were identified, indicating two independent mechanisms of this process. Our results show that under typical environmental conditions (pH and temperature) sulphonamides are hydrolytically stable with a long half-life; they thus contribute to the on-going assessment of their environmental fate. PMID:22579461

Bia?k-Bieli?ska, Anna; Stolte, Stefan; Matzke, Marianne; Fabia?ska, Aleksandra; Maszkowska, Joanna; Ko?odziejska, Marta; Liberek, Beata; Stepnowski, Piotr; Kumirska, Jolanta

2012-04-25

230

Competitive, uncompetitive, and mixed inhibitors of the alkaline phosphatase activity associated with the isolated brush border membrane of the tapeworm Hymenolepis diminuta.  

PubMed

Several compounds were tested as inhibitors of the alkaline phosphatase (AlkPase) activity associated with the isolated brush border membrane of the tapeworm, Hymenolepis diminuta. Molybdate, arsenate, arsenite and beta-glycerophosphate (BGP) were competitive inhibitors of the hydrolysis of p-nitrophenyl phosphate, while levamisole and clorsulon were uncompetitive and mixed inhibitors, respectively. Molybdate was also a competitive inhibitor of the hydrolysis of BGP and 5'-adenosine monophosphate, and levamisole was an uncompetitive inhibitor of BGP hydrolysis. The apparent inhibitor constants (Ki') for molybdate and levamisole were virtually identical regardless of the substrate, and these data support the hypothesis that the AlkPase activity is represented by a single membrane-bound enzyme with low substrate specificity. Quinacrine, Hg2+, and ethylenediaminetetraacetate were also potent inhibitors of the AlkPase activity, but the mechanisms by which these latter three inhibitors function were not clear. PMID:2768348

Pappas, P W; Leiby, D A

1989-06-01

231

Laser enhanced hydrolysis of selected polypeptides  

NASA Astrophysics Data System (ADS)

This project serves as a preliminary examination of selectively enhancing bond cleavage during chemical reactions in biological molecules by using continuous wave infrared lasers. To analyze protein content, polypeptides are broken into their constituent amino acids through hydrolysis. The cleaving of the peptide bond has traditionally been accomplished under harsh conditions, 110°C in 6 N hydrochloric acid for 24 hours. In this project hydrolysis was strongly enhanced by irradiating the dipeptides, threonyl-aspartate and alanyl-alanine, for 30 minutes with coherent infrared radiation from a tunable carbon dioxide laser. The dipeptide tyrosyl-tyrosine, the chemical N- methylacetimide, and the protein BSA were successfully hydrolyzed with the laser. The effect of reaction parameters such as laser power and HCl concentration were studied, as well as the effect of the primary parameter, the beam wavelength. The samples were analyzed using standard biological methods for determining the amino acid concentration, thin layer chromatography and ion exchange chromatography. These methods gave consistent results for the irradiated samples as well as for standard amino acids and polypeptide samples. The results from these methods were used to create the hydrolysis spectra. The catalytic action of the laser was strongly wavelength dependent. The hydrolysis spectra of the molecules were compared to the absorption spectra of the samples. Laser enhanced hydrolysis occurred when the laser wavelength coincided with a line in the dipeptide spectra. This weak line in each of the dipeptide spectra is consistent both in position and strength with a line in NMA, which has been identified as a fundamental mode associated with the peptide bond. From the experimental results, the enhanced process appears to occur in the vapor phase. The initially liquid sample was progressively evaporated, and fully hydrolyzed material was carried to a collection trap by the vapor. It can, in principle, be extracted immediately and continuously, reducing the time involved and the degradation of the samples. If subsequent observations confirm that laser excited molecular resonance affects the reaction in vapor, the implications in physics will be numerous, including the study of atmospheric reactions and other light enhanced vapor phase reactions.

Ouzts, Mary Paige

232

Reactiveincompatibility of cumene hydroperoxide mixedwith alkaline solutions  

Microsoft Academic Search

Cumene hydroperoxide\\u000a (CHP) is classified as a flammable hazard in NFPA 43B. Fires or explosions\\u000a induced by thermal hazards ascribed to the unstable hydroperoxyl or peroxyl\\u000a groups are often reported. This sequence studies is aimed at the decomposition\\u000a phenomena associated with the reactive and incompatible characteristics of\\u000a CHP mixed with alkaline solutions. Various alkalines were used for comparing\\u000a the relative

H. Y. Hou; Y. S. Duh; W. H. Lin; C. M. Shu

2006-01-01

233

Laser direct write of planar alkaline microbatteries  

NASA Astrophysics Data System (ADS)

We are developing a laser engineering approach to fabricate and optimize alkaline microbatteries in planar geometries. The laser direct-write technique enables multicapability for adding, removing and processing material and provides the ability to pattern complicated structures needed for fabricating complete microbattery assemblies. In this paper, we demonstrate the production of planar zinc-silver oxide alkaline cells under ambient conditions. The microbattery cells exhibit 1.55-V open-circuit potentials, as expected for the battery chemistry, and show a flat discharge behavior under constant-current loads. High capacities of over 450 ?Ahcm-2 are obtained for 5-mm2 microbatteries.

Arnold, C. B.; Kim, H.; Piqué, A.

234

The Alkaline Diet: Is There Evidence That an Alkaline pH Diet Benefits Health?  

PubMed Central

This review looks at the role of an alkaline diet in health. Pubmed was searched looking for articles on pH, potential renal acid loads, bone health, muscle, growth hormone, back pain, vitamin D and chemotherapy. Many books written in the lay literature on the alkaline diet were also reviewed and evaluated in light of the published medical literature. There may be some value in considering an alkaline diet in reducing morbidity and mortality from chronic diseases and further studies are warranted in this area of medicine.

Schwalfenberg, Gerry K.

2012-01-01

235

Hydrolysis of ferric chloride in solution  

SciTech Connect

The Detox{trademark} process uses concentrated ferric chloride and small amounts of catalysts to oxidize organic compounds. It is under consideration for oxidizing transuranic organic wastes. Although the solution is reused extensively, at some point it will reach the acceptable limit of radioactivity or maximum solubility of the radioisotopes. This solution could be cemented, but the volume would be increased substantially because of the poor compatibility of chlorides and cement. A process has been developed that recovers the chloride ions as HCl and either minimizes the volume of radioactive waste or permits recycling of the radioactive chlorides. The process involves a two-step hydrolysis at atmospheric pressure, or preferably under a slight vacuum, and relatively low temperature, about 200{degrees}C. During the first step of the process, hydrolysis occurs according to the reaction below: FeCl{sub 3 liquid} + H{sub 2}O {r_arrow} FeOCl{sub solid} + 2 HCl{sub gas} During the second step, the hot, solid, iron oxychloride is sprayed with water or placed in contact with steam, and hydrolysis proceeds to the iron oxide according to the following reaction: 2 FeOCl{sub solid} + H{sub 2}O {r_arrow} Fe{sub 2}O{sub 3 solid} + 2 HCl{sub gas}. The iron oxide, which contains radioisotopes, can then be disposed of by cementation or encapsulation. Alternately, these chlorides can be washed off of the solids and can then either be recycled or disposed of in some other way.

Lussiez, G.; Beckstead, L.

1996-11-01

236

Microbial Thiocyanate Utilization under Highly Alkaline Conditions  

Microsoft Academic Search

Three kinds of alkaliphilic bacteria able to utilize thiocyanate (CNS 2 ) at pH 10 were found in highly alkaline soda lake sediments and soda soils. The first group included obligate heterotrophs that utilized thiocyanate as a nitrogen source while growing at pH 10 with acetate as carbon and energy sources. Most of the heterotrophic strains were able to oxidize

DIMITRY Y. SOROKIN; TATYANA P. TOUROVA; ANATOLY M. LYSENKO; J. GIJS KUENEN

2001-01-01

237

Computer simulation of alkaline earth halides  

Microsoft Academic Search

Monte Carlo calculations have been carried out for model systems consisting of 324 ions (108 cations and 216 anions). The aims were: (a) to study the thermodynamic and structural properties of liquid and solid alkaline earth halides; (b) to test the rigid ion model.Although the general agreement between experimental and predicted properties is less satisfactory than in the case of

Simon W. de Leeuw

1978-01-01

238

Computer simulation of alkaline earth halides  

Microsoft Academic Search

Monte Carlo calculations have been carried out for model systems consisting of 324 ions (108 cations and 216 anions). The aims were: (a) to study the thermodynamic and structural properties of liquid and solid alkaline earth halides; (b) to test the rigid ion model. Although the general agreement between experimental and predicted properties is less satisfactory than in the case

Simon W. de Leeuw

1978-01-01

239

Technical developments in alkaline water electrolysis  

Microsoft Academic Search

A new series of alkaline water electrolysis Hydrogen Generation Systems (HGS) is under development at Teledyne Energy Systems (TES). When introduced to the marketplace in mid 1982, the HGS will be the largest capacity single unit manufactured in the United States. The HGS is the product of a joint development program with the Electric Power Research Institute (EPRI) and TES,

Kincaide

1982-01-01

240

Electrochemistry of Some New Alkaline Battery Electrodes.  

National Technical Information Service (NTIS)

New alkaline battery electrodes used in cells such as nickel oxide-cadmium, nickel oxide-hydrogen, nickel oxide-zinc, and silver oxide-zinc have been developed as a result of contracted and in-house research at the Air Force Aero-Propulsion Laboratory. Ca...

D. F. Pickett R. A. Marsh W. S. Bishop

1976-01-01

241

Negative Electrode For An Alkaline Cell  

DOEpatents

The present invention concerns a negative electrode for an alkaline cell, comprising a current collector supporting a paste containing an electrochemically active material and a binder, characterized in that said binder is a polymer containing hydrophilic and hydrophobic groups, said polymer being selected from an acrylic homopolymer, copolymer and terpolymer, an unsaturated organic acid copolymer and an unsaturated acid anhydride copolymer.

Coco, Isabelle (Talence Cedex, FR); Cocciantelli, Jean-Michel (Bordeaux, FR); Villenave, Jean-Jacques (Talence Cedex, FR)

1998-07-14

242

MERCURIC CHLORIDE CAPTURE BY ALKALINE SORBENTS  

EPA Science Inventory

The paper gives results of bench-scale mechanistic studies of mercury/sorbent reactions that showed that mercuric chloride (HgC12) is readily adsorbed by alkaline sorbents, which may offers a less expensive alternative to the use of activated carbons. A laboratory-scale, fixed-b...

243

Pocket grid for alkaline battery plates  

Microsoft Academic Search

A laminated alkaline battery grid has two thermoplastic outer gridwire network layers and a thermoplastic inner gridwise network layer sandwiched between the outer layers. A plurality of elongated intersecting welds extend as narrow channels in crisscross fashion across the faces of the grid and bond the networks together. The channels are defined by walls formed by the fusion and exudation

1980-01-01

244

Improvements in electrolysis technology in alkaline solution  

Microsoft Academic Search

Potential technologies for the improvement of alkaline electrolyzer performance in the next five to ten years are discussed. Studies of electrode catalysts, separator materials and bipolar electrolyzer designs capable of allowing electrolysis to proceed at higher current densities, lower working potentials, and temperatures no higher than 120 C to reduce electrical requirements and overall development and capital costs are reviewed.

A. J. Appleby; G. Crepy

1979-01-01

245

Leucocyte alkaline phosphatase in neonatal infections.  

PubMed Central

The leucocyte alkaline phosphatase (LAP) score was estimated in healthy and infected neonates. A leucocyte band count was also done simultaneously. The infected group showed a significant (P < 0.001) decrease in the LAP score and a significant (P < 0.001) increase in the band count. These findings are discussed.

Sharma, S. C.

1980-01-01

246

ISSUES WITH ALKALINE TREATMENT OF SLUDGE  

EPA Science Inventory

This presentation begins with a discussion of the use of lime and other alkaline materials from the very earliest times to the present for killing bacteria, viruses and parasites and for controlling odors in wastewaters and sludge. It answers the question "How did EPA arrive at i...

247

Impact of Cell Wall Acetylation on Corn Stover Hydrolysis by Cellulolytic and Xylanolytic Enzymes  

SciTech Connect

Analysis of variously pretreated corn stover samples showed neutral to mildly acidic pretreatments were more effective at removing xylan from corn stover and more likely to maintain the acetyl to xylopyranosyl ratios present in untreated material than were alkaline treatments. Retention of acetyl groups in the residual solids resulted in greater resistance to hydrolysis by endoxylanase alone, although the synergistic combination of endoxylanase and acetyl xylan esterase enzymes permitted higher xylan conversions to be observed. Acetyl xylan esterase alone did little to improve hydrolysis by cellulolytic enzymes, although a direct relationship was observed between the enzymatic removal of acetyl groups and improvements in the enzymatic conversion of xylan present in substrates. In all cases, effective xylan conversions were found to significantly improve glucan conversions achievable by cellulolytic enzymes. Additionally, acetyl and xylan removal not only enhanced the respective initial rates of xylan and glucan conversion, but also the overall extents of conversion. This work emphasizes the necessity for xylanolytic enzymes during saccharification processes and specifically for the optimization of acetyl esterase and xylanase synergies when biomass processes include milder pretreatments, such as hot water or sulfite steam explosion.

Selig, M. J.; Adney, W. S.; Himmel, M. E.; Decker, S. R.

2009-01-01

248

Nonenzymatic hydrolysis of creatine ethyl ester  

Microsoft Academic Search

The rate of the non-enzymatic hydrolysis of creatine ethyl ester (CEE) was studied at 37°C over the pH range of 1.6–7.0 using 1H NMR. The ester can be present in solution in three forms: the unprotonated form (CEE), the monoprotonated form (HCEE+), and the diprotonated form (H2CEE2+). The values of pKa1 and pKa2 of H2CEE2+ were found to be 2.30

Nicholas S. Katseres; David W. Reading; Luay Shayya; John C. DiCesare; Gordon H. Purser

2009-01-01

249

Pretreatment and enzymatic hydrolysis of lignocellulosic biomass  

NASA Astrophysics Data System (ADS)

The performance of soybean hulls and forage sorghum as feedstocks for ethanol production was studied. The main goal of this research was to increase fermentable sugars' yield through high-efficiency pretreatment technology. Soybean hulls are a potential feedstock for production of bio-ethanol due to their high carbohydrate content (?50%) of nearly 37% cellulose. Soybean hulls could be the ideal feedstock for fuel ethanol production, because they are abundant and require no special harvesting and additional transportation costs as they are already in the plant. Dilute acid and modified steam-explosion were used as pretreatment technologies to increase fermentable sugars yields. Effects of reaction time, temperature, acid concentration and type of acid on hydrolysis of hemicellulose in soybean hulls and total sugar yields were studied. Optimum pretreatment parameters and enzymatic hydrolysis conditions for converting soybean hulls into fermentable sugars were identified. The combination of acid (H2SO4, 2% w/v) and steam (140°C, 30 min) efficiently solubilized the hemicellulose, giving a pentose yield of 96%. Sorghum is a tropical grass grown primarily in semiarid and dry parts of the world, especially in areas too dry for corn. The production of sorghum results in about 30 million tons of byproducts mainly composed of cellulose, hemicellulose, and lignin. Forage sorghum such as brown midrib (BMR) sorghum for ethanol production has generated much interest since this trait is characterized genetically by lower lignin concentrations in the plant compared with conventional types. Three varieties of forage sorghum and one variety of regular sorghum were characterized and evaluated as feedstock for fermentable sugar production. Fourier transform infrared spectroscopy (FTIR), scanning electron microscope (SEM) and X-Ray diffraction were used to determine changes in structure and chemical composition of forage sorghum before and after pretreatment and enzymatic hydrolysis process. Up to 72% of hexose yield and 94% of pentose yield were obtained using "modified" steam explosion with 2% sulfuric acid at 140°C for 30 min and enzymatic hydrolysis with cellulase (15 FPU/g cellulose) and beta-glucosidase (50 CBU/g cellulose).

Corredor, Deisy Y.

250

Optimal enzymatic hydrolysis of urinary benzodiazepine conjugates.  

PubMed

Conditions for the enzymatic hydrolysis of benzodiazepine conjugates were systematically examined. Optimal recovery of the free drugs occurs when 1 mL of urine buffered to pH 4.5 is incubated with 5000 U of Helix pomatia beta-glucuronidase at 56 degrees C for 2 h. Urine specimens containing conjugates of temazepam, oxazepam, lorazepam, alpha-hydroxyalprazolam, 2-hydroxyethylflurazepam, and N-desalkyl-3-hydroxyflurazepam as targeted benzodiazepines were used. The freed drugs were quantitated by gas chromatography-mass spectrometry. PMID:7861750

Meatherall, R

251

Xylan as limiting factor in enzymatic hydrolysis of nanocellulose.  

PubMed

The role of xylan as a limiting factor in the enzymatic hydrolysis of cellulose was studied by hydrolysing nanocellulose samples prepared by mechanical fibrillation of birch pulp with varying xylan content. Analyzing the nanocelluloses and their hydrolysis residues with dynamic FT-IR spectroscopy revealed that a certain fraction of xylan remained tightly attached to cellulose fibrils despite partial hydrolysis of xylan with xylanase prior to pulp fibrillation and that this fraction remained in the structure during the hydrolysis of nanocellulose with cellulase mixture as well. Thus, a loosely bound fraction of xylan was predicted to have been more likely removed by purified xylanase. The presence of loosely bound xylan seemed to limit the hydrolysis of crystalline cellulose, indicated by an increase in cellulose crystallinity and by preserved crystal width measured with wide-angle X-ray scattering. Removing loosely bound xylan led to a proportional hydrolysis of xylan and cellulose with the cellulase mixture. PMID:23238342

Penttilä, Paavo A; Várnai, Anikó; Pere, Jaakko; Tammelin, Tekla; Salmén, Lennart; Siika-aho, Matti; Viikari, Liisa; Serimaa, Ritva

2012-11-19

252

Mechanisms of hydrolysis of phenyl- and benzyl 4-nitrophenyl-sulfamate esters.  

PubMed

The kinetics of hydrolysis at medium acid strength (pH interval 2-5) of a series of phenylsulfamate esters 1 have been studied and they have been found to react by an associative S(N)2(S) mechanism with water acting as a nucleophile attacking at sulfur, cleaving the S-O bond with simultaneous formation of a new S-O bond to the oxygen of a water molecule leading to sulfamic acid and phenol as products. In neutral to moderate alkaline solution (pH ? ~ 6-9) a dissociative (E1cB) route is followed that involves i) ionization of the amino group followed by ii) unimolecular expulsion of the leaving group from the ionized ester to give N-sulfonylamine [HN=SO(2)] as an intermediate. In more alkaline solution further ionization of the conjugate base of the ester occurs to give a dianionic species which expels the aryloxide leaving group to yield the novel N-sulfonylamine anion [(-)N=SO(2)]; in a final step, rapid attack of hydroxide ion or a water molecule on it leads again to sulfamic acid. A series of substituted benzyl 4-nitrophenylsulfamate esters 4 were hydrolysed in the pH range 6.4-14, giving rise to a Hammett relationship whose reaction constant is shown to be consistent with the E1cB mechanism. PMID:20976313

Spillane, William J; Thea, Sergio; Cevasco, Giorgio; Hynes, Michael J; McCaw, Cheryl J A; Maguire, Neil P

2010-10-25

253

Recent Alkaline Lakes: Clues to Understanding the Evolution of Early Planetary Alkaline Oceans and Biogenesis  

NASA Astrophysics Data System (ADS)

Abstract New models suggest that terrestrial weathering consumes 0.26GtC/a (72% silicate-, 28% carbonateweathering), equivalent to a loss of one atmospheric C content every 3700a. Rapid weathering leads in volcanic areas to alkaline conditions, illustrated by the crater lake of Niuafo`ou/Tonga and Lake Van/Turkey, the largest soda lake on Earth. Alkaline conditions cause high CaCO3 supersaturation, permineralization of algal mats and growth of stromatolites. Alkaline conditions can nearly depress free [Ca2+] to levels necessary for proteins to function. Therefore early oceans on Earth (and possibly on Mars) should have been alkaline (i.e. "Soda Oceans"). Recent findings of MgSO4 in top soils on Mars may be misleading about the early history of martian oceans.

Kempe, S.; Hartmann, J.; Kazmierczak, J.

2008-09-01

254

Crystal structure of alkaline cellulase K: insight into the alkaline adaptation of an industrial enzyme.  

PubMed

The crystal structure of the catalytic domain of alkaline cellulase K was determined at 1.9 A resolution. Because of the most alkaliphilic nature and it's highest activity at pH 9.5, it is used commercially in laundry detergents. An analysis of the structural bases of the alkaliphilic character of the enzyme suggested a mechanism similar to that previously proposed for alkaline proteases, that is, an increase in the number of Arg, His, and Gln residues, and a decrease in Asp and Lys residues. Some ion pairs were formed by the gained Arg residues, which is similar to what has been found in the alkaline proteases. Lys-Asp ion pairs are disfavored and partly replaced with Arg-Asp ion pairs. The alkaline adaptation appeared to be a remodeling of ion pairs so that the charge balance is kept in the high pH range. PMID:11501997

Shirai, T; Ishida, H; Noda, J; Yamane, T; Ozaki, K; Hakamada, Y; Ito, S

2001-07-27

255

Influence of relativistic effects on hydrolysis of Ra 2+  

Microsoft Academic Search

Summary  Using 224Ra radiotracer the first hydrolysis constant (pK1h) of Ra2+ cations has been determined. The pK1h value of Ra2+ was compared with the pK1h values of other Group 2 cations. It has been shown that the electrostatic hydrolysis model based on assumption that pK1h is a linear function of reciprocal ionic radii (1\\/ri) does not describe well the hydrolysis of

B. Zieli?ska; A. Bilewicz

2005-01-01

256

Hydrolysis of carnosine and related compounds by mammalian carnosinases  

Microsoft Academic Search

Comparative study of hydrolysis of carnosine and a number of its natural derivatives by human serum and rat kidney carnosinase was carried out. The rate of carnosine hydrolysis was 3–4-fold higher then for anserine and ophidine. The rate of homocarnosine, N-acetylcarnosine and carcinine hydrolysis was negligible by either of the enzymes used. Our data show that methylation, decarboxylation or acetylation

Anna Pegova; Hiroki Abe; Alexander Boldyrev

2000-01-01

257

Hydrolysis catalyst effect on sol–gel silica structure  

Microsoft Academic Search

Silica samples were prepared by the sol–gel process varying the hydrolysis catalyst. The samples were characterized by X-ray diffraction and the radial distribution function was determined (R.D.F.). Fourier transform infrared spectroscopy and thermal analysis were also used. It was found that OH-retention capacity as well as order in the material may be modified with hydrolysis catalysts. When the hydrolysis catalyst

M Asomoza; M. P Dom??nguez; S Sol??s; V. H Lara; P Bosch; T López

1998-01-01

258

Influence of carboxyl group on the acid hydrolysis of cellulose  

Microsoft Academic Search

Cellulose isolated from wood is more susceptible than cotton cellulose to homogeneous hydrolysis in phosphoric acid. The influence\\u000a of carboxyl group introduction at the C6 position on the hydrolysis rate of cellulose in 82.5% phosphoric acid was studied\\u000a as a model of the oxidation of cellulose during pulping. The rate constant of hydrolysis for dissolving pulp was larger than\\u000a that

Shuichi Hirosawa; Kazuya Minato; Fumiaki Nakatsubo

2001-01-01

259

Mechanism of cellobiose inhibition in cellulose hydrolysis by cellobiohydrolase  

Microsoft Academic Search

An experimental study of cellobiose inhibition in cellulose hydrolysis by synergism of cellobiohydrolyse I and endoglucanase\\u000a I is presented. Cellobiose is the structural unit of cellulose molecules and also the main product in enzymatic hydrolysis\\u000a of cellulose. It has been identified that cellobiose can strongly inhibit hydrolysis reaction of cellulase, whereas it has\\u000a no effect on the adsorption of cellulase

Yue Zhao; Bin Wu; Baixu Yan; Peiji Gao

2004-01-01

260

Technical bases for precipitate hydrolysis process operating parameters  

SciTech Connect

This report provides the experimental data and rationale in support of the operating parameters for tetraphenylborate precipitate hydrolysis specified in WSRC-RP-92-737. The report is divided into two sections, the first dealing with lab-scale precipitate hydrolysis experimentation while the second part addresses large-scale runs conducted to demonstrate the revised operating parameters in the Precipitate Hydrolysis Experimental Facility (PHEF). The program was in conjunction with reducing the nitrite ion level in DWPF feed.

Bannochie, C.J.; Lambert, D.P.

1992-11-09

261

Technical bases for precipitate hydrolysis process operating parameters. Revision 1  

SciTech Connect

This report provides the experimental data and rationale in support of the operating parameters for tetraphenylborate precipitate hydrolysis specified in WSRC-RP-92-737. The report is divided into two sections, the first dealing with lab-scale precipitate hydrolysis experimentation while the second part addresses large-scale runs conducted to demonstrate the revised operating parameters in the Precipitate Hydrolysis Experimental Facility (PHEF). The program was in conjunction with reducing the nitrite ion level in DWPF feed.

Bannochie, C.J.; Lambert, D.P.

1992-11-09

262

Abiotic degradation (photodegradation and hydrolysis) of imidazolinone herbicides  

Microsoft Academic Search

The abiotic degradation of the imidazolinone herbicides imazapyr, imazethapyr and imazaquin was investigated under controlled conditions. Hydrolysis, where it occurred, and photodegradation both followed first-order kinetics for all herbicides. There was no hydrolysis of any of the herbicides in buffer solutions at pH 3 or pH 7; however, slow hydrolysis occurred at pH 9. Estimated half-lives for the three herbicides

Mohammadkazem Ramezani; Danielle P. Oliver; Rai S. Kookana; Gurjeet Gill; Christopher Preston

2008-01-01

263

Alkaline and alkaline-earth metals compounds as catalysts for the methanolysis of sunflower oil  

Microsoft Academic Search

The catalytic activity and selectivity of several compounds of the alkaline and alkaline-earth metals in the transesterification with methanol at 323K of refined sunflower oil have been evaluated. Catalytic runs were conducted with a molar methanol\\/oil ratio of 12:1 in a batch reactor. The considered catalysts were Li, Na, K, Rb, Cs and Ca hydroxides, Na, K, Ca and Mg

G. Arzamendi; E. Arguiñarena; I. Campo; S. Zabala; L. M. Gandía

2008-01-01

264

Production of alkaline protease by an alkaliphilic bacteria isolated from an alkaline soda lake  

Microsoft Academic Search

A new alkaliphilic strain of Microbacterium producing an alkaline protease was isolated from an alkaline soda lake in Ethiopia.\\u000a High level of protease activity was produced in the presence of glucose and sucrose as carbon sources. The optimum temperature\\u000a and pH for activity were 65°C and 9.5-11.5 respectively. Above 50°C, Ca2+ was required for enzyme activity and stability. At 55

Amare Gessesse; Berhanu A. Gashe

1997-01-01

265

Influence of delignification efficiency with alkaline peroxide on the digestibility of furfural residues for bioethanol production.  

PubMed

Furfural residues (FR), the abundant lignocellulosic residues from commercial furfural production, were delignified with alkaline peroxide process and then taken as substrates for ethanol production by simultaneous saccharification and fermentation (SSF). It was apparent that the delignification efficiency was increased with higher chemical addition and temperature, reaching the maximum removal (73.5%) of lignin. The widespread accessible-cellulose in FR favored the enzymatic hydrolysis and achieved the considerable bioconversion (75.7% with 5FPU+10IU/g substrate). The delignification process increased the relative glucose content and then the bioconversion efficiency, closely relating to the increased specific surface area. As the cellulose contents were higher than 60%, the final conversions conversely fell to around 75%, probably due to the insufficient utilization of all active cellulose with low enzyme cocktails addition. Although the SSF bioconversion slightly decreased as the elevated amount of fermentable cellulose, the maximum of ethanol concentration (16.9g/L) was expectedly obtained. PMID:23934337

Wang, Kun; Yang, Haiyan; Chen, Qian; Sun, Run-Cang

2013-07-10

266

Effects of Alkaline Phosphatase Activity on Nucleotide Measurements in Aquatic Microbial Communities †  

PubMed Central

Alkaline phosphatase (APase) activity was detected in aquatic microbial assemblages from the subtropics to Antarctica. The occurrence of APase in environmental nucleotide extracts was shown to significantly affect the measured concentrations of cellular nucleotides (adenosine triphosphate, adenosine diphosphate, adenosine monophosphate, guanosine triphosphate, uridine triphosphate, and cytidine triphosphate), adenylate energy charge, and guanosine triphosphate/adenosine triphosphate ratios, when conventional methods of nucleotide extraction were employed. Under the reaction conditions specified in this report, the initial rate of hydrolysis of adenosine triphosphate was directly proportional to the activity of APase in the sample extracts and consequently can be used as a sensitive measure of APase activity. A method was devised for obtaining reliable nucleotide measurements in naturally occurring microbial populations containing elevated levels of APase activity. The metabolic significance of APase activity in microbial cells is discussed, and it is concluded that the occurrence and regulation of APase in nature is dependent upon microscale inorganic phosphate limitation of the autochthonous microbial communities.

Karl, D. M.; Craven, D. B.

1980-01-01

267

Hydrolysis of lignocelluloses by penicillium funiculosum cellulase  

SciTech Connect

Enzymatic hydrolysis of cellulose is a promising method for the conversion of waste cellulose to glucose. During the past few years, the development of this technology has proceeded rapidly, with significant advances made in enzyme production, pretreatment, and hydrolysis. A variety of fungi are reported to produce cellulases but among these Trichoderma reesei and its mutants are powerful producers of cellulases. However, the search for new and possibly better sources of cellulase is continued due to the low levels of beta-glucosidase of T. reesei. Penicillium funiculosum produces a complete cellulase having endo-beta-1,4-glucanase (15-20 U/mL), exo-beta-1,4-glucanase (1.5-2.0 U/mL), and high beta-glucosidase (8-10 U/mL). The saccharification of alkali-treated cotton and bagasse by P. funiculosum enzyme was 70 and 63%, respectively. It was possible to obtain glucose concentration as high as 30% using 50% bagasse. It is of interest that the percent saccharification of cellulosic substrates with the Penicillium enzyme is comparable to that of T. reesei cellulase when the same amount of filter paper activity is used, although the endo-glucanase activity of the latter is two to three times higher. This communication reports the studies on saccharification of lignocelluloses by P. funiculosum cellulase and certain studies on the kinetic aspects. (Refs. 15).

Mishra, C.; Rao, M.; Seeta, R.; Srinivasan, M.C.; Deshpande, V.

1984-04-01

268

Muscarinic receptor activation of phosphatidylcholine hydrolysis. Relationship to phosphoinositide hydrolysis and diacylglycerol metabolism  

SciTech Connect

We examined the relationship between phosphatidylcholine (PC) hydrolysis, phosphoinositide hydrolysis, and diacylglycerol (DAG) formation in response to muscarinic acetylcholine receptor (mAChR) stimulation in 1321N1 astrocytoma cells. Carbachol increases the release of (3H)choline and (3H)phosphorylcholine ((3H)Pchol) from cells containing (3H)choline-labeled PC. The production of Pchol is rapid and transient, while choline production continues for at least 30 min. mAChR-stimulated release of Pchol is reduced in cells that have been depleted of intracellular Ca2+ stores by ionomycin pretreatment, whereas choline release is unaffected by this pretreatment. Phorbol 12-myristate 13-acetate (PMA) increases the release of choline, but not Pchol, from 1321N1 cells, and down-regulation of protein kinase C blocks the ability of carbachol to stimulate choline production. Taken together, these results suggest that Ca2+ mobilization is involved in mAChR-mediated hydrolysis of PC by a phospholipase C, whereas protein kinase C activation is required for mAChR-stimulated hydrolysis of PC by a phospholipase D. Both carbachol and PMA rapidly increase the formation of (3H)phosphatidic acid ((3H)PA) in cells containing (3H)myristate-labeled PC. (3H)Diacylglycerol ((3H)DAG) levels increase more slowly, suggesting that the predominant pathway for PC hydrolysis is via phospholipase D. When cells are labeled with (3H)myristate and (14C)arachidonate such that there is a much greater 3H/14C ratio in PC compared with the phosphoinositides, the 3H/14C ratio in DAG and PA increases with PMA treatment but decreases in response to carbachol.

Martinson, E.A.; Goldstein, D.; Brown, J.H. (Univ. of California, San Diego, La Jolla (USA))

1989-09-05

269

Enzymatic hydrolysis of polysaccharide-rich particulate organic waste.  

PubMed

Hydrolysis of organic particulates in rapid fermentative processes can be inhibited. The volatile fatty acids (VFA) released during fermentation reduce pH. Whether VFA or the drop in pH inhibits hydrolysis is unclear. The effects of pH and acetate on the enzymatic hydrolysis of a potato sample that contains both carbohydrate and protein were studied at fixed pH (5-9) in the presence/absence of 20 g/L of acetate. Experimental results showed that the effects of pH and acetate on the hydrolysis of carbohydrate differed from those on the hydrolysis of protein. Numerous kinetic models fitted the hydrolysis data obtained during the first 40 h of hydrolysis when inhibitory effects were insignificant. The Chen-Hashimoto model was used herein to fit the hydrolysis data obtained during 144 h of reaction. Also, the non-competitive inhibition model of three inhibitors (H(+), OH(-), total/undissociated/dissociated acetate) successfully described the inhibition of the hydrolysis of both carbohydrate and protein. PMID:16444752

He, Pin-Jing; Lü, Fan; Shao, Li-Ming; Pan, Xiu-Jiang; Lee, Duu-Jong

2006-04-20

270

Water insoluble residue following acid hydrolysis of water soluble polysaccharides  

SciTech Connect

This paper illustrates a detailed procedure by which acid insoluble polymer residue can be determined. The procedure is quantitative and reproducible. Several water soluble polymers have been evaluated by this procedure. Values for insoluble residues at various hydrolysis times and temperatures for some common oilfield polymers are given. The insoluble residue content varies with the procedure used to do the polymer hydrolysis. During the hydrolysis reaction, the insoluble residue from a cellulosic polymer goes through a minimum, then increases depending upon hydrolysis time, temperature and acid strength. 11 refs.

Pober, K.W.; Hoff, M.H.; Darlington, R.K.

1982-01-01

271

Chemical Remediation of an Ordnance-Related Compound: The Alkaline Hydrolysis of CL-20. Environmental Quality Technology Program.  

National Technical Information Service (NTIS)

Hexanitrohexaazaisowurtzitane (2,4,6,8,10,12- hexanitro-2,4,6,8,10,12- hexaazatetracyclo 5.5.0.05,9.03,11) dodecane or CL-20 has attracted attention as a possible replacement for, or inclusion in, military and space propellants and explosives. CL-20 is a ...

D. R. Felt J. L. Davis L. Santiago

2007-01-01

272

Microwave-assisted hydrolysis of nitroglycerin (NG) under mild alkaline conditions: new insight into the degradation pathway.  

PubMed

Nitroglycerin (NG), a nitrate ester, is widely used in the pharmaceutical industry and as an explosive in dynamite and as propellant. Currently NG is considered as a key environmental contaminant due to the discharge of wastewater tainted with the chemical from the military and pharmaceutical industry. The present study describes hydrolytic degradation of NG (200 microM) at pH 9 using either conventional or microwave-assisted heating at 50 degrees C. We found that hydrolytic degradation of NG inside the microwave chamber was much higher than its degradation using conventional heating. Products distributions in both heating systems were closely related and included nitrite, nitrate, formic acid, and the novel intermediates 2-hydroxypropanedial (OCHCH(OH)HCO) and glycolic acid (CH2(OH)COOH). Two other intermediates glycolaldehyde (CH2(OH)CHO) and glyoxylic acid (CHOCOOH) were only detected in the microwave treated samples. The molar ratio of nitrite to nitrate in the presence and absence of microwave heating was 2.5 and 2.8, respectively. In both microwave assisted and conventional heating a nitrogen mass balance of 96% and 98% and a carbon mass balance of 58% and 78%, respectively, were obtained. The lower C mass recovery might be attributed to further unknown reactions, e.g., polymerization of the aldehydes CH2(OH)CHO, CHOCOOH and OCHCH(OH)HCO. A hydrolytic degradation pathway for NG was proposed involving denitration (loss of 2 NO2(-)) from the two primary carbons and the loss of one nitrate from the secondary carbon to produce 2-hydroxypropanedial. PMID:20129642

Halasz, Annamaria; Thiboutot, Sonia; Ampleman, Guy; Hawari, Jalal

2010-02-02

273

The acid and enzymic hydrolysis of O-acetylated sialic acid residues from rabbit Tamm-Horsfall glycoprotein  

PubMed Central

Rabbit Tamm–Horsfall glycoprotein and bovine submaxillary glycoprotein were both found to contain sialic acid residues which are released at a slow rate by the standard conditions of acid hydrolysis. These residues are also resistant to neuraminidases from Vibrio cholerae and Clostridium perfringens. This behaviour was attributed to the presence of O-acetylated sialic acid, since the removal of O-acetyl groups by mild alkaline treatment normalized the subsequent release of sialic acid from rabbit Tamm–Horsfall glycoprotein by acid and by enzymic hydrolysis. Determination of the O-acetyl residues in rabbit Tamm–Horsfall glycoprotein indicated that on average two hydroxyl groups of sialic acid are O-acetylated, and these were located on the polyhydroxy side-chain of sialic acid or on C-4 and C-8. These findings confirm the assumption that certain O-acetylated forms of sialic acid are not substrates for bacterial neuraminidases. Several explanations have been suggested to explain the effect of O-acetylation of the side-chain on the rate of acidcatalysed hydrolysis of sialic acid residues.

Neuberger, A.; Ratcliffe, Wendy A.

1972-01-01

274

Optimization of food waste hydrolysis in leach bed coupled with methanogenic reactor: effect of pH and bulking agent.  

PubMed

The effects of pH and bulking agents on hydrolysis/acidogenesis of food waste were studied using leach bed reactor (LBR) coupled with methanogenic up-flow anaerobic sludge blanket (UASB) reactor. The hydrolysis rate under regulated pH (6.0) was studied and compared with unregulated one during initial experiment. Then, the efficacies of five different bulking agents, i.e. plastic full particles, plastic hollow sphere, bottom ash, wood chip and saw dust were experimented under the regulated pH condition. Leachate recirculation with 50% water replacement was practiced throughout the experiment. Results proved that the daily leachate recirculation with pH control (6.0) accelerated the hydrolysis rate (59% higher volatile fatty acids) and methane production (up to 88%) compared to that of control without pH control. Furthermore, bottom ash improved the reactor alkalinity, which internally buffered the system that improved the methane production rate (0.182 l CH(4)/g VS(added)) than other bulking agents. PMID:21195606

Xu, Su Yun; Lam, Hoi Pui; Karthikeyan, O Parthiba; Wong, Jonathan W C

2010-11-26

275

In vitro phosphorylation of acetylcholinesterase at non-consensus protein kinase A sites enhances the rate of acetylcholine hydrolysis.  

PubMed

Here, we report that the catalytic subunit of cAMP-dependent protein kinase (PKA) but not casein kinase II or protein kinase C phosphorylates recombinant human acetylcholinesterase (AChE) in vitro. This enhances acetylthiocholine hydrolysis up to 10-fold as compared to untreated AChE, while leaving unaffected the enzyme's affinity for this substrate and for various active and peripheral site inhibitors. Alkaline phosphatase treatment enhanced the electrophoretic migration, under denaturing conditions, of part of the AChE proteins isolated from various mammalian sources and raised the isoelectric point of some of the treated AChE molecules, indicating that part of the AChE molecules are also phosphorylated in vivo. Enhancement of acetylthiocholine hydrolysis also occurred with Torpedo AChE, which has no consensus motif for PKA phosphorylation. Further, mutating the single PKA site in human AChE (threonine-249) did not prevent this enhancement, suggesting that in both cases it was due to phosphorylation at non-consensus sites. In vivo suppression of the acetylcholine hydrolyzing activity of AChE and consequent impairment in cholinergic neurotransmission occur under exposure to both natural and pharmacological compounds, including organophosphate and carbamate insecticides and chemical warfare agents. Phosphorylation of AChE may possibly offer a rapid feedback mechanism that can compensate for impairments in cholinergic neurotransmission, modulating the hydrolytic activity of this enzyme and enabling acetylcholine hydrolysis to proceed under such challenges. PMID:9427520

Grifman, M; Arbel, A; Ginzberg, D; Glick, D; Elgavish, S; Shaanan, B; Soreq, H

1997-11-01

276

Novel alkaline proteases from alkaliphilic bacteria grown on chicken feather  

Microsoft Academic Search

Two alkaline protease producing alkaliphilic bacterial strains, designated as AL-20 and AL-89, were isolated from a naturally occurring alkaline habitat. The two strains were identified as Nesternkonia sp. and Bacillus pseudofirmus, respectively. Both strains grew and produced alkaline protease using feather as the sole source of carbon and nitrogen. Addition of 0.5% glucose to the feather medium increased protease production

Amare Gessesse; Rajni Hatti-Kaul; Berhanu A Gashe; Bo Mattiasson

2003-01-01

277

Actinide-Aluminate Speciation in Alkaline Raditoactive Waste.  

National Technical Information Service (NTIS)

Investigation of behavior of actinides in alkaline media containing Al(III) showed that no aluminate complexes of actinides in oxidation states (III-VII) were formed in alkaline solutions. At alkaline precipitation (pH 10-14) of actinides in presence of A...

D. L. Clark

2001-01-01

278

Nonenzymatic glycosylation of alkaline phosphatase alters its biological  

Microsoft Academic Search

Hyperglycaemia in poorly controlled diabetic patients induces non-enzymatic glycosylation (glycation) of proteins, altering their structure and physiological bioactivity. Alkaline phosphatase (ALP) is a membrane-bound exoenzyme which faces the extracellular compartment. We have investigated the glycation of intestinal alkaline phosphatase in vitro and the consequences of such molecular modifications on certain structural and functional characteristics. The effect of glycation on alkaline

Antonio D. McCarthy; Ana M. Cortizo; Griselda Giménez Segura; Liliana C. Bruzzone; Susana B. Etcheverry

1998-01-01

279

Net alkalinity and net acidity 2: Practical considerations  

Microsoft Academic Search

The pH, alkalinity, and acidity of mine drainage and associated waters can be misinterpreted because of the chemical instability of samples and possible misunderstandings of standard analytical method results. Synthetic and field samples of mine drainage having various initial pH values and concentrations of dissolved metals and alkalinity were titrated by several methods, and the results were compared to alkalinity

Carl S. Kirby; Charles A. Cravotta

2005-01-01

280

Primitive calc-alkaline and alkaline rock types from the Western Mexican Volcanic Belt  

NASA Astrophysics Data System (ADS)

Since the early Pliocene, small volumes of alkaline magmas have erupted in the western Mexican Volcanic Belt (MVB) in close association with the volumetrically dominant calc-alkaline magmas. Both suites include relatively rare "primitive" types, characterized by high Mg#, Cr, and Ni contents. Primitive hypersthene-normative basalts, parental to the calc-alkaline suite, are found along the volcanic front but are absent at greater distances from the trench. The volcanic-front calc-alkaline suites are typically hornblende bearing, indicating relatively high water contents. Associated primitive alkaline magmas at volcanic-front locations also contain hydrous minerals. These nepheline-normative suites include basanites, phlogopite-bearing minettes, and other hornblende-bearing lamprophyres. These are probably the youngest and freshest lamprophyres yet discovered on Earth, and ideal samples for addressing the origin of this exotic class of rocks. On extended MORB-normalized elemental plots, all lamprophyres show patterns similar to the calc-alkaline basalts, but have overall enrichments of 2 to 25X in Ti, K, P, Ba, Sr, light rare earth elements, and other incompatible elements. The lamprophyres show the same strong relative enrichments of Ba, K, and Sr, and depletions in Ti and Nb that characterize the calc-alkaline rocks of western Mexico and all subduction zones. These similarities in relative element abundances support a common source region for all primitive magmas of the western MVB. The primitive calc-alkaline and alkaline rocks of western Mexico show narrow, overlapping ranges in Sr, Nd, and Pb isotopic ratios, also consistent with derivation of all magmas from a common source. The presence of the relatively cold subducted Cocos and Rivera plates below the volcanic front demands that all primitive magmas originated in the depth range 30 to 75 km. These magmas are enriched in Ba, K, Sr, and other elements, probably transported by hydrous fluids rising from the subducted slab. Several lines of evidence support the presence of phlogopite in the source region of western MVB magmas, probably in the form of phlogopite-rich veins cutting asthenospheric peridotite. The first liquids formed upon partial melting of this veined source region will concentrate the vein component and generate the lamprophyres. These lamprophyric melts rarely erupt in arc settings, more commonly forming dikes in the arc crust. Eruption of lamprophyric magmas in the western MVB is favored by through-crustal extensional fracture systems related to active rifting of the Jalisco block from the N. American plate. Larger volumes of calc-alkaline basalt are generated by melting of the same source which dilutes the vein component with larger proportions of peridotitic wall rock.

Luhr, James F.; Allan, James F.; Carmichael, Ian S. E.; Nelson, Stephen A.; Hasenaka, Toshiaki

1989-04-01

281

Photolysis of alkaline-earth nitrates  

NASA Astrophysics Data System (ADS)

Peroxynitrite and nitrite ions are the diamagnetic products of photolysis (with light at a wavelength of 253.7 nm) of alkaline-earth nitrates; the paramagnetic products and hydrogen peroxide were not found. The structural water in alkaline-earth nitrate crystals did not affect the qualitative composition of the photodecomposition products. The quantum yield of nitrite ions was 0.0012, 0.0038, 0.0078, and 0.0091 quanta-1 and that of peroxynitrite ions was 0.0070, 0.0107, 0.0286, and 0.0407 quanta-1 for Sr(NO3)2, Ba(NO3)2, Ca(NO3)2 · 4H2O, and Mg(NO3)2 · 6H2O, respectively.

Kriger, L. D.; Miklin, M. B.; Dyagileva, E. P.; Anan'ev, V. A.

2013-02-01

282

Nitrogen dioxide reaction with alkaline solids  

SciTech Connect

At conditions typical of a bag filter in a coal-fired blue gas, nitrogen dioxide (NO{sub 2}) diluted with nitrogen was exposed to various alkaline and nonalkaline solids in a packed-bed reactor. On nonalkaline solids, 3 mol of NO{sub 2} reacted readily with water to produce 2 mol of nitric acid (HNO{sub 3}) and 1 mol of NO. Alkaline solids such as calcium hydroxide or calcium silicate (from lime and fly ash) produced less NO and neutralized the nitric acid on the surface. A mathematical model developed to predict rates of NO{sub 2} removal on these surfaces successfully compared experimental and predicted rates. These results are relevant to technology for removal of NO{sub x} by addition of methanol to dry scrubbing systems for flue gas desulfurization.

Nelli, C.H.; Rochelle, G.T. [Univ. of Texas, Austin, TX (United States). Dept. of Chemical Engineering

1996-04-01

283

Pyrosequencing reveals the key microorganisms involved in sludge alkaline fermentation for efficient short-chain fatty acids production.  

PubMed

Short-chain fatty acids (SCFAs) have been regarded as the excellent carbon source of wastewater biological nutrient removal, and sludge alkaline (pH 10) fermentation has been reported to achieve highly efficient SCFAs production. In this study, the underlying mechanisms for the improved SCFAs production at pH 10 were investigated by using 454 pyrosequencing and fluorescent in situ hybridization (FISH) to analyze the microbial community structures in sludge fermentation reactors. It was found that sludge fermentation at pH 10 increased the abundances of Pseudomonas sp. and Alcaligenes sp., which were able to excrete extracellular proteases and depolymerases, and thus enhanced the hydrolysis of insoluble sludge protein and polyhydroxyalkanoates (PHA). Meanwhile, the abundance of acid-producing bacteria (such as Clostridium sp.) in the reactor of pH 10 was also higher than that of uncontrolled pH, which benefited the acidification of soluble organic substrates. Further study indicated that sludge fermentation at pH 10 significantly decreased the number of methanogenic archaea, resulting in lower SCFAs consumption and lower methane production. Therefore, anaerobic sludge fermentation under alkaline conditions increased the abundances of bacteria involved in sludge hydrolysis and acidification, and decreased the abundance of methanogenic archaea, which favored the competition of bacteria over methanogens and resulted in the efficient production of SCFAs. PMID:23544425

Zheng, Xiong; Su, Yinglong; Li, Xiang; Xiao, Naidong; Wang, Dongbo; Chen, Yinguang

2013-04-15

284

Biological treatment of alkaline industrial waste waters  

Microsoft Academic Search

The biotechnological treatment of alkaline waste waters (AWW) resulting from the production of caprolactam by the SNIA-viscosa process has been studied. The pollutant in the AWW is 80–120 g litre?1 cyclohexanecarboxysulphonate (CECS) sodium salt with a COD up to 325?000 mg litre?1. Bacterial strains have been isolated which are able to grow on AWW and to degrade the largest possible

S Baccella; G Cerichelli; M Chiarini; C Ercole; E Fantauzzi; A Lepidi; L Toro; F Vegliò

2000-01-01

285

DNA Denaturation Under Freezing in Alkaline Medium  

Microsoft Academic Search

It is generally accepted that DNA conserves its secondary structure after a freeze-thaw cycle. A negligible amount of degradation occurs after this procedure. Degradation becomes appreciable only after multiple cycles of freezing and thawing. In this study, we have found that a single freeze-thaw cycle in alkaline medium (pH ? 10.8) gives rise to denaturation of calf thymus DNA, although

Elena N. Galyuk; Roger M. Wartell; Yury M. Dosin; Dmitri Y. Lando

2009-01-01

286

Surfactant-enhanced alkaline flooding field project  

SciTech Connect

The Tucker sand of Helper (KS) field is a candidate for surfactant-enhanced alkaline flooding. The geology of the Helper site is typical of many DOE Class I reservoirs. The Tucker sand of Helper field was deposited in a fluvial dominated deltaic environment. Helper oil can be mobilized with either chemical system 2 or chemical system 3, as described in this report. Oil fields in the Gulf Coast region are also good candidates for surfactant-enhanced alkaline flooding. The results from laboratory tests conducted in Berea sandstone cores with oil brine from Helper (KS) field are encouraging. The crude oil is viscous and non-acidic and, yet, was mobilized by the chemical formulations described in this report. Significant amounts of the oil were mobilized under simulated reservoir conditions. The results in Berea sandstone cores were encouraging and should be verified by tests with field core. Consumption of alkali, measured with field core, was very low. Surfactant loss appeared to be acceptable. Despite the good potential for mobilization of Helper oil, certain reservoir characteristics such as low permeability, compartmentalization, and shallow depth place constraints on applications of any chemical system in the Tucker sand. These constraints are typical of many DOE Class I reservoirs. Although Hepler field is not a perfect reservoir in which to apply surfactant- enhanced alkaline flooding, Hepler oil is particularly amenable to mobilization by surfactant-enhanced alkaline systems. A field test is recommended, dependent upon final evaluation of well logs and cores from the proposed pilot area. 14 refs., 21 figs., 10 tabs.

French, T.R.

1991-10-01

287

Trace element distribution coefficients in alkaline series  

Microsoft Academic Search

Mineral\\/groundmass partition coefficients for U, Th, Zr, Hf, Ta, Rb, REE, Co and Sc have been systematically measured in olivine, clinopyroxene, amphibole, biotite, Ti-magnetites, titanite, zircon and feldspars, in basaltic to trachytic lavas from alkaline series (Velay, Chaîne des Puys: Massif Central, France and Fayal: Azores). Average partition coefficients are denned within the experimental uncertainty for limited compositional ranges (basalt-hawaiite,

Fabienne Lemarchand; Benoît Villemant; Georges Calas

1987-01-01

288

Alkaline phosphatase of Physarum polycephalum is insoluble.  

PubMed

The plasmodia of Physarum polycephalum grow as multinucleated cells in the presence of sufficient humidity and nutriment. Under non-illuminating conditions, stresses such as low temperature or high concentrations of salts transform the plasmodia into spherules whereas dehydration induces sclerotization. Some phosphatases including protein phosphatase and acid phosphatase have been purified from the plasmodia, but alkaline phosphatase remains to be elucidated. Phosphatase of the plasmodia, spherules and sclerotia was visualized by electrophoresis gel-staining assay using 5-bromo-4-chloro-3-indolyl phosphate. Insoluble fractions of the sclerotia were abundant in phosphatase activity. The phosphatase which was extracted by nonionic detergent was subjected to column chromatography and preparative electrophoresis. Purified phosphatase showed the highest activity at pH 8.8, indicating that this enzyme belongs to alkaline phosphatase. The apparent molecular mass from sodium dodecyl sulfate-polyacrylamide gel electrophoresis under non-reducing condition was estimated to be 100 kDa whereas that under reducing was 105 kDa. An amount of 1% sodium dodecyl sulfate or 0.5 M NaCl had no effects on the activity although the phosphatase showed heat instability, Mg(2+)-dependency and sensitivity to 2-glycerophosphate or NaF. The extracting conditions and enzymatic properties suggest that this alkaline phosphatase which is in a membrane-bound form plays important roles in phosphate metabolism. PMID:17899011

Furuhashi, Kiyoshi

2007-09-26

289

Electrospinning of an Alkaline Polymer Electrolyte  

NASA Astrophysics Data System (ADS)

The polymer electrolyte membrane is a key component of the low temperature fuel cell to block fuel and electron crossover, while enabling ions to pass and complete the half-cell reactions. Proton exchange membranes (PEMs) are anion-containing polymers, such as Nafion, which offer proton conduction pathways. Alkaline polymer electrolytes utilize hydroxyl anions as charge carriers and are currently being researched as an alternative to PEMs because they may offer the use of inexpensive metal catalysts. However, hydroxyl anion in an alkaline electrolyte has relatively low mobility compared to that of protons in an acid electrolyte; hence a high concentration of OH^- is required to obtain high ionic conductivity. Here, we report the use of an electrospinning process to prepare nonwoven membranes. Polysulfones are first functionalized with varied ionic content of quaternary ammonium functional groups and then are electrospun to get alkaline electrolyte mat. The morphology at various ionic content, mechanical property, and in-plane conductivity of resulting films will be discussed and compared to solvent-cast films of the same material.

Roddecha, Supacharee; Dong, Zexuan; Wu, Yiquan; Anthamatten, Mitchell

2010-03-01

290

Characterization of a Baculovirus Alkaline Nuclease†  

PubMed Central

All baculovirus genomes sequenced to date encode a homolog of an alkaline nuclease that has been characterized in the Herpesviridae. In this report we describe the characterization of the alkaline nuclease (AN) homolog of the Autographa californica multinucleocapsid nucleopolyhedrovirus (AcMNPV) (open reading frame 133). His-tagged AN constructs were expressed in recombinant baculoviruses and affinity purified, and then their enzymatic activity was characterized. AN was found to degrade linear DNA at alkaline pH, preferred Mg2+ over Mn2+, had optimal activity at 35°C, and did not appear to have a salt requirement. To rule out contamination by the endogenous baculovirus gene product or a cellular enzyme, point mutations were introduced into a highly conserved domain of the gene. These mutations were found to markedly reduce or eliminate most of the activity of the affinity-purified enzyme. An antibody generated against the protein was used to analyze its expression by Western blot analysis. AN was found to be expressed at low levels by 12 h postinfection, with maximal expression at 24 h postinfection. Attempts to generate a virus with this gene inactivated were unsuccessful, suggesting that AN may be encoded by an essential gene.

Li, Lulin; Rohrmann, George F.

2000-01-01

291

Functional ionic liquids for hydrolysis of lignocellulose.  

PubMed

An efficient system for hydrolysis of lignocellulosic materials to prepare reducing sugar in a series of functional acidic ionic liquids with low synthetic cost and excellent dissolved and catalytic activity was established. High yield of reducing sugar was obtained with the use of 1-H-3-methylimidazolium chloride ([HMIM]Cl). The use of ionic liquid under ultrasound irradiation greatly improved the yield of total reducing sugar. The optimum reaction conditions were as follows: ratio of water/sample was 5 (w/w), ratio of IL/sample was 25 (w/w), 70°C, 120 min and the yield of reducing sugar was up to 53.27 mg from 0.2g of soybean straw and 50.03 mg from 0.2g of corn straw. PMID:23769534

Hu, Xiaomei; Xiao, Yibo; Niu, Kun; Zhao, Yang; Zhang, Bixian; Hu, Baozhong

2013-04-30

292

Fermentable sugars by chemical hydrolysis of biomass  

PubMed Central

Abundant plant biomass has the potential to become a sustainable source of fuels and chemicals. Realizing this potential requires the economical conversion of recalcitrant lignocellulose into useful intermediates, such as sugars. We report a high-yielding chemical process for the hydrolysis of biomass into monosaccharides. Adding water gradually to a chloride ionic liquid-containing catalytic acid leads to a nearly 90% yield of glucose from cellulose and 70–80% yield of sugars from untreated corn stover. Ion-exclusion chromatography allows recovery of the ionic liquid and delivers sugar feedstocks that support the vigorous growth of ethanologenic microbes. This simple chemical process, which requires neither an edible plant nor a cellulase, could enable crude biomass to be the sole source of carbon for a scalable biorefinery.

Binder, Joseph B.; Raines, Ronald T.

2010-01-01

293

Defense waste processing facility precipitate hydrolysis process  

SciTech Connect

Sodium tetraphenylborate and sodium titanate are used to assist in the concentration of soluble radionuclide in the Savannah River Plant's high-level waste. In the Defense Waste Processing Facility, concentrated tetraphenylborate/sodium titanate slurry containing cesium-137, strontium-90 and traces of plutonium from the waste tank farm is hydrolyzed in the Salt Processing Cell forming organic and aqueous phases. The two phases are then separated and the organic phase is decontaminated for incineration outside the DWPF building. The aqueous phase, containing the radionuclides and less than 10% of the original organic, is blended with the insoluble radionuclides in the high-level waste sludge and is fed to the glass melter for vitrification into borosilicate glass. During the Savannah River Laboratory's development of this process, copper (II) was found to act as a catalyst during the hydrolysis reactions, which improved the organic removal and simplified the design of the reactor.

Doherty, J P; Eibling, R E; Marek, J C

1986-03-01

294

Kinetic study of the acid hydrolysis of sugar cane bagasse  

Microsoft Academic Search

Economic interest in xylitol production can be enhanced if the needed xylose solutions can be obtained from the hydrolysis of low-cost lignocellulosic wastes. Sugar cane bagasse is a renewable, cheap and widely available waste in tropical countries. The hydrolysis of sugar cane bagasse to obtain xylose solutions has a double consequence, the elimination of a waste and the generation of

R Aguilar; J. A Ram??rez; G Garrote; M Vázquez

2002-01-01

295

Hydrolysis of dietary fat by pancreatic lipase stimulates cholecystokinin release  

Microsoft Academic Search

Background & Aims: The hypothesis that cholecystokinin release requires adequate dietary fat digestion in the small intestine was investigated in 10 healthy volunteers, and the consequences of reduced fat hydrolysis on pancreaticobiliary secretions were assessed. Methods: Fat hydrolysis was inhibited by intraduodenal perfusion of tetrahydrolipstatin, an irreversible lipase inhibitor. An oil emulsion containing 0, 30, 60, or 120 mg tetrahydrolipstatin

Pius Hildebrand; Christophe Petrig; Beat Burckhardt; Silvia Ketterer; Hans Lengsfeld; André Fleury; Paul Hadváry; Christoph Beglinger

1998-01-01

296

Kinetics of hydrolysis of chloroform and bromoform in aqueous solutions  

Microsoft Academic Search

The base-catalyzed hydrolysis of chloroform (CF) and bromoform (BF) was examined in water-methanol solutions. The progress of reaction was determined by following the decrease in [OH?] and the increase in [halide] ions as function of time. The effects of temperature, [OH?] and the water: methanol ratio on the rates of reaction were tested in some detail. The hydrolysis of CF

A. M. Shams El Din; Rasheed A. Arain; A. A. Hammoud

1998-01-01

297

Effect of annealing on the hydrolysis of sago starch granules  

Microsoft Academic Search

Sago starch annealed at varying temperatures, time intervals and pH was used to study granule hydrolysis by a glucoamylase (AMG) and ?-amylase (Termamyl) mixture. Differential scanning calorimetry (DSC) indicated that there was a relationship between the extent of annealing and starch granule hydrolysis. Enthalpy of gelatinisation of annealed starch granules remained unchanged, suggesting that no gelatinisation had occurred. The degree

W. J. Wang; A. D. Powell; C. G. Oates

1997-01-01

298

The laccase-catalyzed modification of lignin for enzymatic hydrolysis  

Microsoft Academic Search

The efficient use of cellulases in the hydrolysis of pretreated lignocellulosic biomass is limited due to the presence of lignin. Lignin is known to bind hydrolytic enzymes nonspecifically, thereby reducing their action on carbohydrate substrates. The composition and location of residual lignin therefore seem to be important for optimizing the enzymatic hydrolysis of lignocellulosic substrates. The use of lignin-modifying enzymes

Ulla Moilanen; Miriam Kellock; Sari Galkin; Liisa Viikari

299

Enhanced functional properties of tannic acid after thermal hydrolysis  

Technology Transfer Automated Retrieval System (TEKTRAN)

Thermal hydrolysis processing of fresh tannic acid was carried out in a closed reactor at four different temperatures (65, 100, 150 and 200°C). Pressures reached in the system were 1.3 and 4.8 MPa at 150 and 200°C, respectively. Hydrolysis products (gallic acid and pyrogallol) were separated and qua...

300

Polymer-assisted dithane hydrolysis with minimum workup.  

PubMed

The first solid-phase-assisted protocol for the hydrolysis of dithioacetals is described using three different functionalized ion exchange resins. The hydrolysis and the purification proceed under milder conditions than common homogeneously employed reagents so that very reactive carbonyl compounds can be prepared. PMID:18271599

Luiken, Silke; Kirschning, Andreas

2008-02-14

301

Mechanism of hydrolysis of a novel indolocarbazole topoisomerase I inhibitor  

Microsoft Academic Search

The degradation kinetics and reaction product profile of the antitumor agent 1 in aqueous solution was studied. Hydrolysis of the pendant imide ring of 1 is the primary mode of thermal degradation in aqueous solution, and the pH rate profile of 1 has a V-shape indicating that hydrolysis of the imide ring can be catalyzed by either acid or base.

David Breslin; Yuichi Sato; Shyam B. Karki

2010-01-01

302

Ultrasound Enhancement of Enzymatic Hydrolysis of Cellulose Plant Matter  

Technology Transfer Automated Retrieval System (TEKTRAN)

The work reported here is based on acceleration of enzymatic hydrolysis of plant biomass substrate by introduction of low intensity, uniform ultrasound field into a reaction chamber (bio-reactor). This method may serve as improvement of rates in the hydrolysis of cellulosic materials to sugars, whi...

303

THE MECHANISM OF THE HYDROLYSIS OF METHYLENE CHLORIDE  

Microsoft Academic Search

chloride with aqueous chloride solution and proposed the mechanism of the reaction!). The kinetics of the hydrolysis of methylene chloride has now been investigated over the pH range from ° to 12 under the same experimental conditions as those in the exchange reaction reported in the foregoing paper!). It has been found that the rate of the hydrolysis is approximately

Kozo TANABE; Masayuki MATSUDA

304

Preparation and Properties of Sirups Made by Hydrolysis of Lactose  

Microsoft Academic Search

Clear, nearly colorless sirups were prepared from lactose by hydrolysis with either lactase (~3-galactosidase) or hydrochloric acid, followed by decolor- ization, ion exchange demineralization, and concentration. Crystallization of sugars from the sirups was reduced by decreasing total solids from 66 to 60% and the degree of hydrolysis from 95 to 75%; however, overall stability of sirup with respect to both

E. J. Guy; L. F. Edmondson

1978-01-01

305

Phosphorus deficiency and kinetics of alkaline phosphatase in isolates and natural populations of phototrophic sulphur bacteria.  

PubMed

Phosphorus deficiency was analysed in the oxic-anoxic gradient of the karstic sulphurous lakes Vilar and Sisó during the stratification period. The distribution of planktonic photosynthetic populations along a vertical gradient coincided with an increase in alkaline phosphatase activity (APA). A multiple stepwise correlation analysis of data yielded a positive correlation of APA with planktonic phototrophic populations. MUF-P hydrolysis saturation curves were used to estimate the enzyme kinetics. High-affinity phosphatases (i.e. low K(M) saturation constant) coincided with the oxic-anoxic gradient and progressively declined through both the epi- and the hypolimnion. Changes in the K(M) values are likely due to phosphate inhibition and the contribution of different planktonic populations in the induction of alkaline phosphatases. Extremely low organic phosphorus turnover times (as short as 0.37 h) were also estimated in the gradient zone, indicating a high dependence of the bacterial populations on organic phosphate esters. Phosphatase saturation kinetics revealed K(M) values from 0.53 to 8.45 microM MUF-P, perfectly matching those found in the isolates Thiocapsa sp. UdG3513, Chlorobium limicola UdG6050 and UdG6055 and Chlorobium phaeobacteroides CL1401. The results obtained indicate that a relevant adaptation of sulphur phototrophic bacteria may occasionally face periods of phosphate limitation despite thriving in nutrient-rich anoxic waters. PMID:20491922

Bañeras, Lluis; Ros-Ponsatí, Marta; Cristina, Xavier P; Garcia-Gil, Jesus L; Borrego, Carles M

2010-04-23

306

Alkaline hydrogen peroxide pretreatment of cashew apple bagasse for ethanol production: study of parameters.  

PubMed

The alkaline hydrogen peroxide (AHP) pretreatment of cashew apple bagasse (CAB) was evaluated based on the conversion of the resultant cellulose into glucose. The effects of the concentration of hydrogen peroxide at pH 11.5, the biomass loading and the pretreatment duration performed at 35°C and 250 rpm were evaluated after the subsequent enzymatic saccharification of the pretreated biomass using a commercial cellulase enzyme. The CAB used in this study contained 20.56 ± 2.19% cellulose, 10.17 ± 0.89% hemicellulose and 35.26 ± 0.90% lignin. The pretreatment resulted in a reduced lignin content in the residual solids. Increasing the H2O2 concentration (0-4.3% v/v) resulted in a higher rate of enzymatic hydrolysis. Lower biomass loadings gave higher glucose yields. In addition, no measurable furfural and hydroxymethyl furfural were produced in the liquid fraction during the pretreatment. The results show that alkaline hydrogen peroxide is effective for the pretreatment of CAB. PMID:23665519

Correia, Jessyca Aline da Costa; Júnior, José Edvan Marques; Gonçalves, Luciana Rocha B; Rocha, Maria Valderez Ponte

2013-04-01

307

Alkaline peroxide delignification of agricultural residues to enhance enzymatic saccharification. [Trichoderma reesei  

SciTech Connect

Approximately one-half of the lignin and most of the hemicellulose present in agricultural residues such as wheat straw and corn stover are solubilized when the residue is treated at 25/sup 0/C in an alkaline solution of hydrogen peroxide. The delignification reaction is most efficient when the ratio of hydrogen peroxide to substrate is at least 0.25 (w/w) and the pH is 11.5. The supernatant fraction from a given pretreatment, after addition of makeup peroxide and readjustment of the pH, can be recycled to treat at least six additional batches of substrate, resulting in a substantial concentration of hemicellulose and soluble lignin degradation products. Hydrolysis of the insoluble fraction with Trichoderma reesei cellulase after alkline peroxide treatment yields glucose with almost 100% efficiency, based upon the cellulose content of the residue before treatment. These data indicate that alkaline peroxide pretreatment is a simple and efficient method for enhancing the enzymatic digestibility of lignocellulosic crop residues to levels approaching the theoretical maximum.

Gould, J.M.

1984-01-01

308

Purification and characterisation of alkaline cellulase produced by a novel isolate, Bacillus sphaericus JS1.  

PubMed

A novel strain of Bacillus sphaericus JS1 producing thermostable alkaline carboxymethyl cellulase (CMCase; endo-1,4-beta-glucanase, E.C. 3.2.1.4) was isolated from soil using Horikoshi medium at pH 9.5. CMCase was purified 192-fold by (NH(4))(2)SO(4) precipitation, ion exchange and gel filtration chromatography, with an overall recovery of 23%. The CMCase is a multimeric protein with a molecular weight estimated by native-PAGE of 183 kDa. Using SDS-PAGE a single band is found at 42 kDa. This suggests presence of four homogeneous polypeptides, which would differentiate this enzyme from other known alkaline cellulases. The activity of the enzyme was significantly inhibited by bivalent cations (Fe(3+) and Hg(2+), 1.0 mM each) and activated by Co(2+), K(+) and Na(+). The purified enzyme revealed the products of carboxymethyl cellulose (CMC) hydrolysis to be CM glucose, cellobiose and cellotriose. Thermostability, pH stability, good hydrolytic capability, and stability in the presence of detergents, surfactants, chelators and commercial proteases make this enzyme potentially useful in laundry detergents. PMID:14758556

Singh, Jagtar; Batra, Navneet; Sobti, Ranbir Chander

2004-01-31

309

Mesozoic mafic alkaline magmatism of southern Scandinavia  

NASA Astrophysics Data System (ADS)

More than 100 volcanic necks in central Scania (southern Sweden) are the product of Jurassic continental rift-related mafic alkaline magmatism at the southwest margin of the Baltic Shield. They are mainly basanites, with rarer melanephelinites. Both rock groups display overlapping primitive Mg-numbers, Cr and Ni contents, steep chondrite-normalized rare earth element patterns (LaN /YbN = 17 27) and an overall enrichment in incompatible elements. However, the melanephelinites are more alkaline and have stronger high field strength element enrichment than the basanites. The existence of distinct primary magmas is also indicated by heterogeneity in highly incompatible element ratios (e.g. Zr/Nb, La/Nb). Trace element modelling indicates that the magmas were generated by comparably low degrees of melting of a heterogeneous mantle source. Such a source can best be explained by a metasomatic overprint of the mantle lithosphere by percolating evolved melts. The former existence of such alkaline trace element-enriched melts can be demonstrated by inversion of the trace element content of green-core clinopyroxenes and anorthoclase which occur as xenocrysts in the melanephelinites and are interpreted as being derived from crystallization of evolved mantle melts. Jurassic magmatic activity in Scania was coeval with the generation of nephelinites in the nearby Egersund Basin (Norwegian North Sea). Both Scanian and North Sea alkaline magmas share similar trace element characteristics. Mantle enrichment processes at the southwest margin of the Baltic Shield and the North Sea Basin generated trace element signatures similar to those of ocean island basalts (e.g. low Zr/Nb and La/Nb) but there are no indications of plume activity during the Mesozoic in this area. On the contrary, the short duration of rifting, absence of extensive lithospheric thinning, and low magma volumes argue against a Mesozoic mantle plume. It seems likely that the metasomatic imprint resulted from the earlier Permo-Carboniferous rifting episode which affected the entire study area and clearly was accompanied by plume activity (Ernst and Buchan in American Geophysical Union, pp 297 337, 1997). Renewed rifting in Jurassic times triggered decompression melting in the volatile-enriched lithospheric mantle and the alkaline melts generated inherited the earlier “stored” plume signature.

Tappe, Sebastian

2004-11-01

310

Hydrothermal Alkalinity in Central Nepal Rivers  

NASA Astrophysics Data System (ADS)

Numerous hot springs flow along the base of the Himalayan front, at or near the Main Central Thrust, in the Narayani drainage of central Nepal. The springs are found in a narrow zone characterized by rapid uplift and high incision rates. In this zone, hot rocks are brought to the near-surface where they interact with meteoric waters to produce the hydrothermal system. Water-rock interaction produces springs with high solute loads (TDS up to 8000 mg/L.) The springs drive significant chemical anomalies (e.g. Cl, Na, K and Ge) in the rivers that flow through the hydrothermal zone In order to quantify the impact the springs have on the river chemistry, the spring discharge must be estimated. Direct measurement of the spring discharge is difficult, as the springs often flow within the stream bed itself or are inaccessible. We take advantage of the wide disparity in stream vs. hydrothermal [Ge] to calculate spring discharge by chemical mass balance. The hot springs have [Ge] up to 684 nmol/kg and Ge/Si ratios from 200 to 1000 ?mol/mol while river waters have [Ge] near 0.15 nmol/kg and Ge/Si ratios near 0.5 ?mol/mol, typical of non-polluted rivers. The discharge calculated from the Ge mass balance for individual springs ranges from 0.03 x 106 to 5.6 x 106 m3/yr, and accounts for a small percentage of the total river discharge (0.03% to 1.9%). The hot spring discharge for all of central Nepal is around 1.5x108 m3/yr, 0.5% of the Narayani river discharge. Distinguishing between silicate and carbonate sources is important to assessing the role of weathering on atmospheric CO2 levels and the relative contributions of silicate and carbonate alkalinity in central Nepal rivers are still not well resolved. The hot springs derive up to 100% of their alkalinity from silicate sources. Using the discharge estimates for the springs, we find that the sum of the silicate alkalinity fluxes from all the spring systems is 2.8 x 108 mol/yr. This implies that the hot springs deliver around 18% of the silicate alkalinity in the Narayani river, and ca. 2% of the total alkalinity. Geothermal activity in this active orogenic belt is an important geochemical flux, directly coupling chemical fluxes to tectonic processes.

Evans, M. J.; Derry, L. A.

2002-12-01

311

Alkaline and ultrasound assisted alkaline pretreatment for intensification of delignification process from sustainable raw-material.  

PubMed

Alkaline and ultrasound-assisted alkaline pretreatment under mild operating conditions have been investigated for intensification of delignification. The effect of NaOH concentration, biomass loading, temperature, ultrasonic power and duty cycle on the delignification has been studied. Most favorable conditions for only alkaline pretreatment were alkali concentration of 1.75N, solid loading of 0.8% (w/v), temperature of 353K and pretreatment time of 6h and under these conditions, 40.2% delignification was obtained. In case of ultrasound-assisted alkaline approach, most favorable conditions obtained were alkali concentration of 1N, paper loading of 0.5% (w/v), sonication power of 100W, duty cycle of 80% and pretreatment time of 70min and the delignification obtained in ultrasound-assisted alkaline approach under these conditions was 80%. The material samples were characterized by FTIR, SEM, XRD and TGA technique. The lignin was recovered from solution by precipitation method and was characterized by FTIR, GPC and TGA technique. PMID:23978705

Subhedar, Preeti B; Gogate, Parag R

2013-08-13

312

The hydrolysis of phosphatidylcholine by an immobilized lipase: Optimization of hydrolysis in organic solvents  

Microsoft Academic Search

The ability of a commercial immobilized lipase preparation (Lipozyme) to hydrolyze the fatty acyl ester bonds of soybean phosphatidylcholine\\u000a in organic media was investigated. Response surface methodology, based on a Modified Central Composite design, was employed\\u000a to examine the effects on hydrolysis of solvent polarity, water, pH, duration and temperature of incubation, and the amounts\\u000a of substrate and catalyst. A

M. J. Haas; D. J. Cichowicz; J. Phillips; R. Moreau

1993-01-01

313

Modeling of autocatalytic hydrolysis of adefovir dipivoxil in solid formulations.  

PubMed

The stability and hydrolysis kinetics of a phosphate prodrug, adefovir dipivoxil, in solid formulations were studied. The stability relationship between five solid formulations was explored. An autocatalytic mechanism for hydrolysis could be proposed according to the kinetic behavior which fits the Prout-Tompkins model well. For the classical kinetic models could hardly describe and predict the hydrolysis kinetics of adefovir dipivoxil in solid formulations accurately when the temperature is high, a feedforward multilayer perceptron (MLP) neural network was constructed to model the hydrolysis kinetics. The build-in approaches in Weka, such as lazy classifiers and rule-based learners (IBk, KStar, DecisionTable and M5Rules), were used to verify the performance of MLP. The predictability of the models was evaluated by 10-fold cross-validation and an external test set. It reveals that MLP should be of general applicability proposing an alternative efficient way to model and predict autocatalytic hydrolysis kinetics for phosphate prodrugs. PMID:21467805

Dong, Ying; Zhang, Yan; Xiang, Bingren; Deng, Haishan; Wu, Jingfang

2011-04-01

314

Waste activated sludge hydrolysis during ultrasonication: two-step disintegration.  

PubMed

In order to clearly describe the hydrolysis of waste activated sludge (WAS) during ultrasonication by a 2-step disintegration process, concentrations of ribonucleic acid (RNA) and bound extracellular polymeric substance (EPS) were measured. Apparently, different decreasing patterns of RNA and EPS concentrations during WAS hydrolysis made it possible to distinguish the floc disintegration (FD) and cell lysis (CL). Initially, FD and CL appear to take simultaneously, but the dominant hydrolytic process is shifted from FD to CL after 10 min of ultrasonication. Additional kinetic analysis of WAS hydrolysis was also conducted. A five-fold greater hydrolysis rate constant of FD relative to that of CL was observed, reflecting the different strengths of floc and cells. Therefore, different rates of increased solubilization during WAS hydrolysis appear to account for the initial disintegration of the rather loose part (sludge floc) and the subsequent disintegration of the rigid part (microbial cells). PMID:22850171

Cho, Si-Kyung; Shin, Hang-Sik; Kim, Dong-Hoon

2012-07-16

315

Arginine Coordination in Enzymatic Phosphoryl Transfer: Evaluation of the Effect of Arg166 Mutations in Escherichia Coli Alkaline Phosphatase  

SciTech Connect

Arginine residues are commonly found in the active sites of enzymes catalyzing phosphoryl transfer reactions. Numerous site-directed mutagenesis experiments establish the importance of these residues for efficient catalysis, but their role in catalysis is not clear. To examine the role of arginine residues in the phosphoryl transfer reaction, we have measured the consequences of mutations to arginine 166 in Escherichia coli alkaline phosphatase on hydrolysis of ethyl phosphate, on individual reaction steps in the hydrolysis of the covalent enzyme-phosphoryl intermediate, and on thio substitution effects. The results show that the role of the arginine side chain extends beyond its positive charge, as the Arg166Lys mutant is as compromised in activity as Arg166Ser. Through measurement of individual reaction steps, we construct a free energy profile for the hydrolysis of the enzyme-phosphate intermediate. This analysis indicates that the arginine side chain strengthens binding by {approx}3 kcal/mol and provides an additional 1-2 kcal/mol stabilization of the chemical transition state. A 2.1 {angstrom} X-ray diffraction structure of Arg166Ser AP is presented, which shows little difference in enzyme structure compared to the wild-type enzyme but shows a significant reorientation of the bound phosphate. Altogether, these results support a model in which the arginine contributes to catalysis through binding interactions and through additional transition state stabilization that may arise from complementarity of the guanidinum group to the geometry of the trigonal bipyramidal transition state.

O'Brien, P.J.; Lassila, J.K.; Fenn, T.D.; Zalatan, J.G.; Herschlag, D.

2009-05-22

316

Concentration and separation of vanadium from alkaline media by strong alkaline anion-exchange resin 717  

Microsoft Academic Search

With strong alkaline anion-exchange resin 717 as the sorbent and NaOH solution as the eluent, a study on the sorption from\\u000a alkaline solution and elution of vanadium(V), silicon(IV), and aluminium(III) was carried out. Different parameters affecting\\u000a the sorption and elution process, including temperature, pH values as well as the ratio of resin to solution, were investigated.\\u000a The results show that

Jinwen Huang; Peng Su; Wenwei Wu; Sen Liao; Huiquan Qin; Xuehang Wu; Xiaohu He; Liujia Tao; Yanjin Fan

2010-01-01

317

Alkaline and enzymatic degradation of L-lactide copolymers, 1. Amorphous-made films of L-lactide copolymers with D-lactide, glycolide, and epsilon-caprolactone.  

PubMed

Films of poly(L-lactide) [i.e., poly(L-lactic acid) (PLLA)] and L-lactide copolymers with glycolide [P(LLA-GA)(81/19)], epsilon-caprolactone [P(LLA-CL)(82/18)], D-lactide [P(LLA-DLA)(95/5), (77/23), and (50/50)] were prepared and a comparative study on the effects of comonomer type and content on alkaline and proteinase K-catalyzed hydrolyses of the films was carried out. The hydrolyzed films were investigated using gravimetry (weight loss and water absorption), differential scanning calorimetry (DSC), polarimetry, and gel permeation chromatography (GPC). To exclude the effects of molecular weight and crystallinity on the hydrolysis, the films were prepared from polymers having similar molecular weights and made amorphous by melt-quenching. It was found that incorporation of hydrophilic glycolide units in L-lactide chains raises the alkaline and enzymatic hydrolyzabilities, whereas incorporation of hydrophobic epsilon-caprolactone units in L-lactide chains reduces the alkaline and enzymatic hydrolyzabilities. On the other hand, incorporation of D-lactide units with the same hydrophilicity of L-lactide units increases the alkaline hydrolyzability but decreases the enzymatic hydrolyzability. The alkaline hydrolyzability of the films of L-lactide copolymers with different kinds of comonomers and P(LLA-DLA) with different D-lactide unit contents can be closely related to their hydrophilicity. On the other hand, the enzymatic hydrolyzability of L-lactide copolymer films with different kinds of comonomers is mainly determined by hydrophilicity, while that of P(LLA-DLA) films is determined by the averaged L-lactyl and D-lactyl unit sequence lengths. The catalytic effect of proteinase K relative to that of alkali on the hydrolysis of P(LLA-DLA)(77/23) and P(LLA-GA)(81/19) films normalized by that of PLLA was lower than unity, whereas the normalized relative catalytic effect of proteinase K on the hydrolysis of P(LLA-CL)(82/18) film was higher than unity, meaning that despite low absolute alkaline and enzymatic hydrolyzability of the P(LLA-CL)(82/18) film, the catalytic effect of proteinase K may be maintained for this copolymer film, probably because of its blocky structure. PMID:15729721

Tsuji, Hideto; Tezuka, Yasufumi

2005-02-23

318

Induction of Rat Liver Alkaline Phosphatase by Bile Duct Ligation  

PubMed Central

Bile duct ligation causes a five- to sevenfold increase in the activity of rat liver alkaline phosphatase within 12 hours after ligation and a similar rise in the activity of alkaline phosphatase in serum. The increased serum activity is due entirely to the appearance of a new isoenzyme that has the properties of rat liver alkaline phosphatase. The increase in both serum and liver alkaline phosphatase is prevented by the prior administration of cycloheximide in a dose that inhibits protein synthesis by 70%. Rat liver alkaline phosphatase was then purified to homogeneity. Antibody was raised to purified rat liver alkaline phosphatase in rabbits. The antibody was coupled to sepharose 4B and affinity columns made. 3-H-leucine was then injected into the portal veins of sham operated rats and rats with bile duct ligation four hours after ligation. One hour after injection and five hours after ligation, animals were sacrificed. Liver alkaline phosphatase was purified by means of affinity chromatography and double immunoprecipitation with rabbit antibody to rat liver alkaline phosphatase and goat anti-rabbit gamma globulin. Bile duct ligation increased the incorporation of 3-H-leucine into liver alkaline phosphatase more than threefold compared with sham operated rats, 164 CPM/mg protein vs. 49 CPM/mg protein (p < .001). The data indicate that the increased activity of rat liver alkaline phosphatase after bile duct ligation is due to enzyme induction rather than to activation of a pre-existing, relatively inactive enzyme. ImagesFIG. 1FIG. 4

Kaplan, Marshall M.

1979-01-01

319

Alkaline biofiltration of H2S odors.  

PubMed

Hydrogen sulfide (H2S) is a very common odor nuisance which is best controlled by chemical or biological scrubbing. Under alkaline pH, the amount of H2S that can be solubilized in a scrubbing liquid increases significantly, and therefore, gas-liquid mass transfer limitations can be reduced. To date, biological scrubbing of H2S has been limited to neutral or acidic pH, despite the potential benefit of reduced mass transfer limitations at alkaline pH. In the present paper, an alkaliphilic sulfoxidizing bacterial consortium was deployed in a laboratory-scale biotrickling filter treating H2S at pH 10. The gas contact time ranged from 1 to 6 s, and H2S inlet concentrations, from 2.5 to 18 ppm(v). The results showed that under most conditions, H2S removal exceeded 98% and the degradation end-product was sulfate. At the highest H2S concentrations and shortest gas contacttimes, when the loading exceeded 30 g m(-3) h(-1), the H2S removal efficiency decreased significantly due to biological reaction limitation, and incompletely oxidized sulfides were measured in the trickling liquid. An analysis of the process demonstrated that operating the biotrickling filter at high pH results in an enhancement of the mass transfer by a factor of 1700-11 000. Overall, alkaline biotrickling filtration was shown to be very effective at low concentration of H2S and very short gas contact time. This is the first demonstration of a biotrickling filter for air pollution control operated at high pH. PMID:18939577

González-Sánchez, Armando; Revah, Sergio; Deshusses, Marc A

2008-10-01

320

Factors limiting the hydrolysis of casein by subtilisin DY.  

PubMed

It was shown that during the subtilisin DY-induced hydrolysis of casein relatively stable polypeptide structures are formed. In their interior these structures contain peptide bonds which are susceptible to the enzyme used. Heating (up to 100 degrees C) and/or application of ultrasound (25 kHz, 60 W) results in their unfolding. Data are provided, which show that under the enzyme-substrate complex formation does not lead to an enzyme conformation more susceptible to autolysis. Taking into account the described phenomena a higher degree of hydrolysis was attained in comparison to those obtained by standard enzymatic hydrolysis. PMID:3322321

Nedkov, P; Lilova, A; Tchorbanov, B

1987-10-01

321

Acid hydrolysis of pretreated lignocellulose from corn residue  

SciTech Connect

The lignocellulose derived from the hemicellulose hydrolysis of corn residue was steeped in 15 to 25% sulfuric acid at 40 to 103 degrees C, filtered to recover solids, and then dried in a fluidized bed dryer to concentrate the acid. Acid concentration, steeping temperature, drying time, and temperature effects are described by the current work. Hydrolysis of the pretreated lignocelloses gave 90% cellulose conversion with acid consumption corresponding to 1.50 g H/sub 2/SO/sub 4//g glucose and sugar concentrations in the hydrolyzate of up to 6.5 wt% in the best cases. Kinetic parameters are presented which describe the observed rates and extent of hydrolysis.

Bienkowski, P.R.; Ladisch, M.R.; Voloch, M.; Tsao, G.T.

1984-01-01

322

Enzymatic hydrolysis of polylactic acid fiber.  

PubMed

This study investigated the optimization of the enzymatic processing conditions for polylactic acid (PLA) fibers using enzymes consisting of lipases originating from different sources. The hydrolytic activity was evaluated taking into consideration the pH, temperature, enzyme concentration, and treatment time. The structural change of the PLA fibers was measured in the optimal treatment conditions. PLA fiber hydrolysis by lipases was maximized for lipase from Aspergillus niger at 40 °C for 60 min at pH 7.5 with 60% (owf) concentration, for lipase from Candida cylindracea at 40 °C for 120 min at pH 8.0 with 70% (owf) concentration, and for lipase from Candida rugosa at 45 °C for 120 min at pH 8.0 with 70% (owf) concentration. There was a change in protein absorbance of the treatment solution before and after all lipase treatments. The analyses of the chemical structure change and structural properties of the PLA due to lipase treatment was confirmed by tensile strength, differential scanning calorimetry, wide-angle X-ray scattering diffractometry, Fourier transform infrared spectroscopy, and scanning electron microscopy. PMID:21038086

Lee, So Hee; Song, Wha Soon

2010-10-31

323

The Chemistry of Paper Preservation: Part 4. Alkaline Paper  

NASA Astrophysics Data System (ADS)

The inherent instability of old papers is largely due to the presence of acids which catalyze the hydrolytic degradation of cellulose. The use of alkaline paper can minimize the problem of acidity for new papers. This study focuses on the chemistry involved in the sizing of both acid and alkaline papers and the types of fillers used. The waterproofing agent that is used in acid paper is alum-precipitated rosin size, which tends to spread and create a hydrophobic surfaces over the cellulose fibers. Alkaline paper uses the synthetic sizing agents, alkyl ketene dimers(AKD) and alkyl succinic anhydrides (ASA). These alkaline sizing agents become chemically bound to the cellulose fibers with hydrophobic chains pointing outward, producing a water repellent surface. The sizing reactions take place in a neutral-to-alkaline medium. Calcium carbonate can then be used as a filler to replace expensive titanium dioxide. Finally, the advantages and potential problems in alkaline paper making are discussed.

Carter, Henry A.

1997-05-01

324

Advanced inorganic separators for alkaline batteries  

NASA Astrophysics Data System (ADS)

A flexible, porous battery separator comprising a coating applied to a porous, flexible substrate is described. The coating comprises: (1) a thermoplastic rubber-based resin which is insoluble and unreactive in the alkaline electrolyte; (2) a polar organic plasticizer which is reactive with the alkaline electrolyte to produce a reaction product which contains a hydroxyl group and/or a carboxylic acid group; and (3) a mixture of polar particulate filler materials which are unreactive with the electrolyte, the mixture comprising at least one first filler material having a surface area of greater than 25 meters sq/gram, at least one second filler material having a surface area of 10 to 25 sq meters/gram, wherein the volume of the mixture of filler materials is less than 45% of the total volume of the fillers and the binder, the filler surface area per gram of binder is about 20 to 60 sq meters/gram, and the amount of plasticizer is sufficient to coat each filler particle. A method of forming the battery separator is also described.

Sheibley, D. W.

1982-05-01

325

Discovery of Alkaline Volcanic Rocks on Mars  

NASA Astrophysics Data System (ADS)

Based on remote sensing measurements and the compositions of martian meteorites, the surface of Mars is inferred to be dominated by subalkaline mafic volcanic rocks. However, the Spirit rover has recently discovered lavas of alkalic composition. Picritic (Adirondack class) basalts with high alkali and low silica contents were previously analyzed on the plains of Gusev Crater, and two new classes of dark, fine-grained, relatively unaltered volcanic rocks with distinctive thermal emission spectra have now been found as float and in a possible dike at high elevations in the Columbia Hills. Chemical analyses indicate that these rocks are mildly alkaline basalt and trachybasalt, respectively. Their mineralogy consists of Na- and K-rich feldspar(s), low- and high-Ca pyroxenes, ferroan olivine, Fe-Ti (and possibly Cr) oxides, phosphate, and possibly glass. Chemical compositions of these rocks lie along a MELTS-calculated liquid line of descent for Adirondack class basalt. Systematic changes in normative mineralogy are consistent with the calculated magmatic fractionation. We infer that Backstay- and Irvine-class magmas may have formed by low-pressure fractionation of primitive, oxidized Adirondack-class magmas and were possibly emplaced coevally with the plains basalts. The compositions of these rocks reveal that the Gusev magmatic province is alkaline, distinct from the subalkaline volcanic rocks thought to dominate most of the planet's surface. This discovery may have implications for the composition of the martian mantle source region and the conditions under which it melted.

McSween, H. Y.; Team, A. S.

2006-05-01

326

DNA DAMAGE QUANTITATION BY ALKALINE GEL ELECTROPHORESIS.  

SciTech Connect

Physical and chemical agents in the environment, those used in clinical applications, or encountered during recreational exposures to sunlight, induce damages in DNA. Understanding the biological impact of these agents requires quantitation of the levels of such damages in laboratory test systems as well as in field or clinical samples. Alkaline gel electrophoresis provides a sensitive (down to {approx} a few lesions/5Mb), rapid method of direct quantitation of a wide variety of DNA damages in nanogram quantities of non-radioactive DNAs from laboratory, field, or clinical specimens, including higher plants and animals. This method stems from velocity sedimentation studies of DNA populations, and from the simple methods of agarose gel electrophoresis. Our laboratories have developed quantitative agarose gel methods, analytical descriptions of DNA migration during electrophoresis on agarose gels (1-6), and electronic imaging for accurate determinations of DNA mass (7-9). Although all these components improve sensitivity and throughput of large numbers of samples (7,8,10), a simple version using only standard molecular biology equipment allows routine analysis of DNA damages at moderate frequencies. We present here a description of the methods, as well as a brief description of the underlying principles, required for a simplified approach to quantitation of DNA damages by alkaline gel electrophoresis.

SUTHERLAND,B.M.; BENNETT,P.V.; SUTHERLAND, J.C.

2004-03-24

327

Molecular modeling of human alkaline sphingomyelinase  

PubMed Central

Alkaline sphingomyelinase, which is expressed in the human intestine and hydrolyses sphingomyelin, is a component of the plasma and the lysosomal membranes. Hydrolase of sphingomyelin generates ceramide, sphingosine, and sphingosine 1-phosphate that have regulatory effects on vital cellular functions such as proliferation, differentiation, and apoptosis. The enzyme belongs to the Nucleotide Pyrophosphatase/Phosphodiesterase family and it differs in structural similarity with acidic and neutral sphingomyelinase. In the present study we modeled alkaline sphingomyelinase using homology modeling based on the structure of Nucleotide Pyrophosphatase/Phosphodiesterase from Xanthomonas axonopodis with which it shares 34% identity. Homology modeling was performed using Modeller9v7. We found that Cys78 and Cys394 form a disulphide bond. Further analysis shows that Ser76 may be important for the function of this enzyme, which is supported by the findings of Wu et al. (2005), that S76F abolishes the activity completely. We found that the residues bound to Zn2+ are conserved and geometrically similar with the template. Molecular Dynamics simulations were carried out for the modeled protein to observe the effect of Zinc metal ions. It was observed that the metal ion has little effect with regard to the stability but induces increased fluctuations in the protein. These analyses showed that Zinc ions play an important role in stabilizing the secondary structure and in maintaining the compactness of the active site.

Suresh, Panneer Selvam; Olubiyi, Olujide; Thirunavukkarasu, Chinnasamy; Strodel, Birgit; Kumar, Muthuvel Suresh

2011-01-01

328

Characterization of spent AA household alkaline batteries.  

PubMed

The aim of this work is identification of the structural components of actual domestic spent alkaline AA batteries, as well as quantification of some of their characteristics. Weight, humidity, ash content, zinc and zinc oxide on anode, manganese on cathode and other metals, potassium hydroxide on the internal components and heating values for papers, anode and cathode were determined in several batteries. As expected, cathode, anode and the steel can container are the main contributors to the 23.5 g average weight of the batteries. Cathode is also the major contributor to the positive heating value of the batteries as well as to the heavy metals content. Mercury was detected in very low levels in these mercury-free batteries. Zinc and zinc oxide amounts in the anodes are highly variable. Results obtained were compared to information on alkaline batteries in the literature from 1993 to 1995; and a positive evolution in their manufacture is readily apparent. Data from the producer of batteries shows some small discrepancies relative to the results of this experimental work. PMID:15964181

Almeida, Manuel F; Xará, Susana M; Delgado, Julanda; Costa, Carlos A

2005-06-16

329

The effect of alkaline agents on retention of EOR chemicals  

SciTech Connect

This report summarizes a literature survey on how alkaline agents reduce losses of surfactants and polymers in oil recovery by chemical injection. Data are reviewed for crude sulfonates, clean anionic surfactants, nonionic surfactants, and anionic and nonionic polymers. The role of mineral chemistry is briefly described. Specific effects of various alkaline anions are discussed. Investigations needed to improve the design of alkaline-surfactant-polymer floods are suggested. 62 refs., 28 figs., 6 tabs.

Lorenz, P.B.

1991-07-01

330

Hydrolysis of carbaryl by carbonate impurities in reference clay SWy-2.  

PubMed

The influence of clay preparation methods on the sorption and hydrolysis of carbaryl (1-naphthyl, N-methyl carbamate) by K+-saturated reference smectite SWy-2 was studied. Four methods were utilized: (1) The reference (or specimen) clay used as received was K+-saturated (hereafter referred to as whole clay). (2) High-speed centrifugation (3295g) of whole clay resulted in a pellet with three discrete bands. The upper, light-colored, low-density band was obtained by manual separation (light fraction). The high-density, dark-colored material comprising the lower band (heavy fraction) was also obtained manually. (3) SWy-2 was subjected to overnight gravity sedimentation to obtain the <2 microm particles (clay-sed.) and then K+-saturated. (4) SWy-2 was subjected to low-speed centrifugation (58-60g) to separate the <2 microm particle size (clay-cent.) and then K+-saturated. Each preparation of mineral fractions manifested significantly different abilities to hydrolyze carbaryl to 1-naphthol, decreasing in the order whole clay > heavy fraction > clay-sed. > light clay > clay-cent. The extent of 1-naphthol disappearance from solution, accompanied by a progressive darkening of the clay, followed the order whole clay > heavy fraction > light clay > clay-sed. > clay-cent. Using ring labeled [14C]carbaryl, approximately 61 and 15% of the total 14C activity added to the whole clay and light fraction, respectively, remained unextractable. X-ray diffraction of the heavy fraction revealed several peaks corresponding to minor impurities, including calcite and dolomite. Aqueous slurries of whole clay, light fraction, clay-sed., and heavy fraction were alkaline, whereas the pH of slurried clay-cent. was neutral. It was concluded that dissolution of inorganic carbonate impurities in SWy-2 caused alkaline conditions in the slurries leading to the hydrolysis of carbaryl. Dissolution of carbonates with sodium acetate buffer eliminated hydrolytic activity associated with SWy-2. None of the four preparation methods reliably removed inorganic carbonates. The use of commercial or reference smectites in surface chemistry studies should be accompanied by a treatment with acetate buffer to remove carbonate impurities. PMID:15612797

Arroyo, L Jacqueline; Li, Hui; Teppen, Brian J; Johnston, Cliff T; Boyd, Stephen A

2004-12-29

331

Rechargeable Zn-MnO sub 2 alkaline batteries  

SciTech Connect

In this paper progress in the development of rechargeable alkaline zinc-manganese dioxide cells is described. The advantages and limitations of the system are evaluated. Laboratory tests run on commercial primary alkaline cells as well as model simulations of a bipolar MnO{sub 2} electrode show that the rechargeable alkaline battery may be able to compete with lead-acid, nickel-cadmium, and secondary lithium cells for low- to moderate-rate applications. However, because of this poor performance at high rates and low temperatures, the alkaline MnO{sub 2} battery is not suitable for present automotive starting applications.

Wruck, W.J.; Reichman, B.; Bullock, K.R.; Kao, W.H. (Corporate Applied Research, Johnson Controls, Inc., Milwaukee, WI (US))

1991-12-01

332

Acid-alkaline balance: role in chronic disease and detoxification.  

PubMed

In conclusion, the increasing dietary acid load in the contemporary diet can lead to a disruption in acid-alkaline homeostasis in various body compartments and eventually result in chronic disease through repeated borrowing of the body's alkaline reserves. Adjustment of tissue alkalinity, particularly within the kidney proximal tubules, can lead to the more effective excretion of toxins from the body. Metabolic detoxification using a high vegetable diet in conjunction with supplementation of an effective alkalizing compound, such as potassium citrate, may shift the body's reserves to become more alkaline. PMID:17658124

Minich, Deanna M; Bland, Jeffrey S

333

High Temperature Acid Hydrolysis of Cellulose for Alcohol Fuel Production.  

National Technical Information Service (NTIS)

In the past decade, a concerted effort has been made to develop a process for converting renewable lignocellulosic feedstocks into ethanol fuels. This can be accomplished by the hydrolysis of cellulose and hemicellulose to their component sugars and subse...

J. D. Wright

1983-01-01

334

Enantioselective Synthesis of (-)-Sclerophytin A by a Stereoconvergent Epoxide Hydrolysis  

PubMed Central

The cytotoxic natural product (-)-sclerophytin A was constructed in 13 steps from geranial. Highlights from the synthesis are a stereoselective Oshima-Utimoto reaction, a Shibata-Baba indium-promoted radical cyclization, and a novel stereoconvergent epoxide hydrolysis.

Wang, Bin; Ramirez, Armando P.; Slade, Justin J.; Morken, James P.

2010-01-01

335

INTERIM PROTOCOL FOR MEASURING HYDROLYSIS RATE CONSTANTS IN AQUEOUS SOLUTIONS  

EPA Science Inventory

A detailed protocol was developed to measure first- and second-order hydrolysis rate constants for organic chemicals for use in models for predicting persistence in aquatic systems. The protocol delineates theoretical considerations, laboratory experiments, and calculation proced...

336

Hydrolysis of Cellulose by Purified Cellulase Components: Synergistic Effects.  

National Technical Information Service (NTIS)

The hydrolysis of cellulose by purified cellulase components is reported. The adsorption of purified cellobiohydrolases (CBH I and II) and endoglucanases (EG I and II) from Trichoderma reesei strain L27 to microcrystalline cellulose (Avicel) has been stud...

J. Woodward N. E. Lee

1987-01-01

337

Production of Alcohol Fuels Via Acid-Hydrolysis Extrusion Technology.  

National Technical Information Service (NTIS)

Pilot plant data obtained using a modified single screw grain extruder to facilitate the conversion of raw cellulosic materials into fermentable monosaccharides via acid hydrolysis are analyzed. The following are discussed: cellulose availability and cost...

R. Noon T. Hochstetler

1981-01-01

338

Effect of Solvents on the Hydrolysis Reaction of Tetramethyl Orthosilicate.  

National Technical Information Service (NTIS)

High-pressure Raman spectroscopy is used to monitor the hydrolysis reaction of tetramethyl orthosilicate, TMOS, in solutions with methanol, acetonitrile, acetone, dioxane and formamide. The rate constants are experimentally determined for different temper...

T. W. Zerda G. Hoang

1990-01-01

339

Hydrolysis of fMet-tRNA by Peptidyl Transferase  

PubMed Central

Escherichia coli and rabbit reticulocyte (f[3H]Met-tRNA·AUG·ribosome) intermediates undergo hydrolysis, with release of f[3H]methionine, upon addition of tRNA or CpCpA in the presence of acetone. This ribosomal catalyzed reaction has similar requirements, pH optimum, and antibiotic sensitivity to those of peptidyl transferase. Two antibiotics, lincomycin with E. coli ribosomes and anisomycin with reticulocyte ribosomes, inhibit peptide-bond formation and transesterification activities of peptidyl transferase, but stimulate hydrolysis of f[3H]Met-tRNA. Earlier studies have suggested peptidyl transferase activity is essential for R factor-dependent hydrolysis of f(3H)Met-tRNA. These studies indicate that peptidyl transferase has the capacity for f(3H)Met-tRNA hydrolysis and, therefore, may be responsible for peptidyl-tRNA cleavage during peptide chain termination.

Caskey, C. T.; Beaudet, A. L.; Scolnick, E. M.; Rosman, M.

1971-01-01

340

Studies on the Enzymatic Hydrolysis of Organophosphate Poisons in Pigs.  

National Technical Information Service (NTIS)

Phosphate paraoxon was studied in Yorkshire pig, rat and human sera. Enzymatic hydrolysis was significantly affected by certain buffers in the reaction mixture. Kinetic measurements suggest that more than one enzyme hydrolyzes the organophosphate. Dependi...

P. Schmid J. Jaeger

1982-01-01

341

Value of Furfural/Ethanol Coproduction from Acid Hydrolysis Processes.  

National Technical Information Service (NTIS)

The benefits of two modifications in the acid hydrolysis of cellulosic feedstocks for the production of ethanol fuels were investigated: marketing of the by-product furfural and xylose fermentation. Preliminary analysis indicate that the furfural by-produ...

S. Parker M. Calnon D. Feinberg A. Power L. Weiss

1983-01-01

342

Rapid spot test for the determination of esculin hydrolysis.  

PubMed Central

Esculin hydrolysis is a useful test in the differentiation of both gram-positive and gram-negative bacteria covering a wide spectrum of aerobes, facultative anaerobes, and anaerobes. Commonly utilized methods require a minimum of 18 h of incubation in broth or agar medium and utilize the production of a brown-black compound, due to the combination of ferric ions with the hydrolysis product esculetin, as indicator. A procedure is presented that requires 15 to 30 min for completion and utilizes fluorescence loss as the indicator of hydrolysis. Esculin fluoresces at 366 nm, whereas the hydrolysis product esculetin does not. Over 1,400 strains of gram-positive and gram-negative bacteria were tested. There was 98.4% of correlation between the spot test and esculin broth and 97% correlation with the bile-esculin agar. Images

Edberg, S C; Gam, K; Bottenbley, C J; Singer, J M

1976-01-01

343

Hydrolysis of disaccharides over solid acid catalysts under green conditions  

Microsoft Academic Search

The hydrolysis of the three most important disaccharides: sucrose, maltose and cellobiose, has been comparatively studied in mild conditions (50–80°C) in water over several solid acid catalysts. Strong acidic resins (Amberlite A120 and A200), mixed oxides (silica-alumina and silica-zirconia), and niobium-containing solids (niobic acid, silica-niobia, and niobium phosphate) have been chosen as acid catalysts. The hydrolysis activity was studied in

Matteo Marzo; Antonella Gervasini; Paolo Carniti

344

Hydrothermal pre-treatment and enzymatic hydrolysis of sunflower stalks  

Microsoft Academic Search

The production of fermentable sugars by biochemical conversion of pretreated sunflower stalks is studied in this work. Liquid hot water pre-treatment, in a temperature range from 180 to 230°C was used. After pre-treatment, solid residue and liquid fractions are separated by filtration. Pretreated solids are further submitted to enzymatic hydrolysis for glucose release using a commercial enzyme preparation. Enzymatic hydrolysis

Manuel J. Díaz; Cristóbal Cara; Encarnación Ruiz; Mercedes Pérez-Bonilla; Eulogio Castro

2011-01-01

345

Alcohol fermentation of sweet potato. Membrane reactor in enzymic hydrolysis  

Microsoft Academic Search

Use of ultrafiltration membrane systems in stirred cell and in thin-channel systems for immobilizing enzyme (sweet potato intrinsic and crystalline beta-amylase) in hydrolysis of sweet potato through a continuous operation mode were studied. Both the filtration rate and reducing sugars, produced as the result of enzymic hydrolysis, decreased with the filtration time. The immobilized enzymes in the thin-channel system showed

A. Azhar; M. K. Hamdy

1981-01-01

346

Enhanced functional properties of tannic acid after thermal hydrolysis  

Microsoft Academic Search

Thermal hydrolysis processing of fresh tannic acid was carried out in a closed reactor at four different temperatures (65, 100, 150 and 200°C). Pressures reached in the system were 1.3 and 4.8MPa at 150 and 200°C, respectively. Hydrolysis products (gallic acid and pyrogallol) were separated and quantified by HPLC. Gallic acid and pyrogallol production was increased (p?0.05) when heated to

T. J. Kim; J. L. Silva; Y. S. Jung

2011-01-01

347

Hydrolysis of methyl parathion in a flooded soil  

Microsoft Academic Search

Methyl parathion (O, O-dimethyl O-p-nitrophenyl phosphorothioate ) (MP) is used widely for controlling insect pests and vectors of diseases in agriculture and public health. MP, like ethyl parathion (Sethunathan et al. 1977), may undergo degradation in soil and water environments by hydrolysis, nitro group reduction or both.Hydrolysis is the major pathway in nonflooded soil while MP is degraded essentially by

M. Sharmila; K. Ramanand; N. Sethunathan

1989-01-01

348

Standardization of investment casting process using modified binder hydrolysis  

Microsoft Academic Search

A full factorial 23 matrix was designed to study the bending strength, permeability and hoop-stress of investment moulds. A novel method of ethyl-silicate\\u000a hydrolysis; two-step hydrolysis, was used. The results indicate that the bending strength is directly proportional to the\\u000a quantity of filler material in the slurry. Grain size of stucco material appears to exert the least effect on bending

Kayala Mallikharjuna Babu; P Martin Jebaraj; M P Chowdiah

1990-01-01

349

Sugar fatty acid ester surfactants: Base-catalyzed hydrolysis  

Microsoft Academic Search

Rate constants for the base-catalyzed hydrolysis of sucrose laurate, sucrose ?-sulfonyl laurate, and sucrose ?-ethyl laurate\\u000a were measured at several temperatures in pH 11 buffer. Activation energies and Arrhenius factors for the hydrolysis reactions\\u000a were determined. At 27C, sucrose laurate hydrolyzed fastest and sucrose ?-ethyl laurate slowest. Activation energies and\\u000a Arrhenius factors showed that both steric and electronic factors affect

Irene J. A. Baker; D. Neil Furlong; Franz Grieser; Calum J. Drummond

2000-01-01

350

Adenine Nucleotide Hydrolysis in Patients with Aseptic and Bacterial Meningitis  

Microsoft Academic Search

The meningitis is a disease with high mortality rates capable to cause neurologic sequelae. The adenosine (the final product\\u000a of ATP hydrolysis by ectonucleotidases), have a recognized neuroprotective actions in the central nervous system (CNS) in\\u000a pathological conditions. The aim of the present study was evaluate the adenine nucleotides hydrolysis for to verify one possible\\u000a role of ATP, ADP and

Aracélli Gnatta Dorneles; Charlene Menezes; Rita Leal Sperotto; Marta Medeiros Frescura Duarte; Vera Maria Morsch; Maria Rosa Chitolina Schetinger; Vânia Lúcia Loro

2009-01-01

351

Enzymatic hydrolysis and fermentation of agricultural residues to ethanol  

Microsoft Academic Search

A combined enzymatic hydrolysis and fermentation process was used to convert steam-treated wheat and barley straw to ethanol. Maximum conversion efficiencies were obtained when the substrates were steamed for 90 s. These substrates could yield over 0.4 g ethanol\\/g cellulose following a combined enzymatic hydrolysis and fermentation process procedure using culture filtrates derived from Trichoderma harzianum E58. When culture filtrates

M. Mes-Hartree; C. M. Hogan; J. N. Saddler

1984-01-01

352

Enzymatic hydrolysis of corncob and ethanol production from cellulosic hydrolysate  

Microsoft Academic Search

Enzymatic hydrolysis of corncob and ethanol fermentation from cellulosic hydrolysate were investigated. After corncob was pretreated by 1% H2SO4 at 108°C for 3h, the cellulosic residue was hydrolyzed by cellulase from Trichoderma reesei ZU-02 and the hydrolysis yield was 67.5%. Poor cellobiase activity in T. reesei cellulase restricted the conversion of cellobiose to glucose, and the accumulation of cellobiose caused

Ming Chen; Liming Xia; Peijian Xue

2007-01-01

353

[Enhanced hydrolysis of waste activated sludge by biosurfactant].  

PubMed

The effects of biosurfactant on the hydrolysis of waste activated sludge including reaction time, dosage of rhamnolipid and pH were investigated. It was found that the rhamnolipid could greatly reduce the surface tension of sludge hydrolysis liquid, resulting in the solubilization of organic solid and the release of extracellular enzyme. During the hydrolysis process, the concentrations of SCOD, soluble reducing sugar and soluble protein showed an obvious increase in the initial and then decrease later. Sludge hydrolysis process fitted to the first-order reaction dynamics within 6 h. At rhamnolipid dosage of 0.3 g x g(-1), the concentrations of SCOD, reducing sugar and protein after 6 h of hydrolysis increased from 371.9, 93.3 and 9.0 mg x L(-1) to 3 994.5, 800.0 and 401.7 mg x L(-1), respectively. The efficiency of sludge hydrolysis was improved with the increase of pH value, and the maximal concentrations of SCOD, reducing sugar and protein were, respectively, 5 249.9, 1658.3 and 597.1 mg x L(-1) at pH 11. PMID:23243881

Yi, Xin; Luo, Kun; Yang, Qi; Li, Xiao-Ming; Deng, Wei-Guang; Zhang, Zhi-Ping

2012-09-01

354

Enzymatic hydrolysis of waste sugarcane bagasse in water media.  

PubMed

Enzymatic hydrolysis of natural cellulose such as sugarcane bagasse is usually carried out in a buffer medium. In this paper, the enzymatic hydrolysis of a waste sugarcane bagasse in water media was carried out.The bagasse was pre-treated with heating explosion and pure (ion exchange), reverse-osmosis and tap water media were used in place of a buffer solution in the hydrolysis process. The yields for reducing sugars and the changes in solution pH and electric conductivity during the hydrolysis under various conditions were studied. The results were also compared with those obtained in buffer solutions. Similar levels of sugar yields were obtained in water and buffer solution media. The pH of the hydrolyzate was in the range of 4.5 - 5.0, which coincided with the optimum pH for the enzyme reaction. It was considered that the enzyme and the substrate formed a transitional complex in the hydrolysis process. The transitional complex provided the buffering capacity pH 5. The results indicate of the hydrolyzate solution at around that industrialization of the enzymatic hydrolysis in a water medium is feasible. PMID:12361374

Zheng, C; Lei, Y; Yu, Q; Lui, X; Huan, K

2002-09-01

355

Adenine nucleotide hydrolysis in patients with aseptic and bacterial meningitis.  

PubMed

The meningitis is a disease with high mortality rates capable to cause neurologic sequelae. The adenosine (the final product of ATP hydrolysis by ectonucleotidases), have a recognized neuroprotective actions in the central nervous system (CNS) in pathological conditions. The aim of the present study was evaluate the adenine nucleotides hydrolysis for to verify one possible role of ATP, ADP and AMP hydrolysis in inflammatory process such as meningitis. The hydrolysis was verified in cerebrospinal fluid (CSF) from human patients with aseptic and bacterial meningitis. Our results showed that the ATP hydrolysis was reduced 12.28% (P < 0.05) in bacterial meningitis and 22% (P < 0.05) in aseptic meningitis. ADP and AMP hydrolysis increased 79.13% (P < 0.05) and 26.37% (P < 0.05) in bacterial meningitis, respectively, and 57.39% (P < 0.05) and 42.64% (P < 0.05) in aseptic meningitis, respectively. This may be an important protective mechanism in order to increase adenosine production. PMID:18712598

Dorneles, Aracélli Gnatta; Menezes, Charlene; Sperotto, Rita Leal; Duarte, Marta Medeiros Frescura; Morsch, Vera Maria; Schetinger, Maria Rosa Chitolina; Loro, Vânia Lúcia

2008-08-20

356

Study of enzyme adsorption and reaction kinetics for cellulose hydrolysis  

SciTech Connect

Enzymatic hydrolysis of cellulose occurs due to the combined catalytic action of two types of cellulase components commonly referred to as C/sub 1/ and C/sub x/. However, before the hydrolysis reaction can begin, it is necessary for these enzymes to first adsorb onto the accessible surfaces of the insoluble cellulose substrate. The objective of the study was to gain a better understanding of the relationships between the adsorption of these enzyme components, the hydrolysis kinetics, the cellulosic surface area accessible to the enzymes, and the cellulose crystallinity. These relationships were investigated by passing a Trichoderma viride cellulase solution through columns of cellulose powder having different accessibility and crystallinity, and then analyzing the quantities of the different enzyme components and the hydrolysis product in the effluent. The amounts of the different cellulase components were analyzed using high-performance anion-exchange chromatography. Additional adsorption and hydrolysis experiments were done using columns of cellulose beads specially developed to provide amodel substrate for this analysis. A mathematical model has been formulated to describe the kinetics of enzyme adsorption and the resultant, initial hydrolysis rate in cellulose column. The analytical solutions obtained have been linearized into a convenient form so that the kinetic parameters of the model can be readily determined from experimental breakthrough curves.

Gilbert, I.G.

1982-01-01

357

Dilute Acid Hydrolysis of Cellulose and Cellulosic Bio-Waste Using a Microwave Reactor System  

Microsoft Academic Search

The dilute acid hydrolysis of grass and cellulose with phosphoric acid was undertaken in a microwave reactor system. The experimental data and reaction kinetic analysis indicate that this is a potential process for cellulose and hemi-cellulose hydrolysis, due to a rapid hydrolysis reaction at moderate temperatures. The optimum conditions for grass hydrolysis were found to be 2.5% phosphoric acid at

A. Orozco; M. Ahmad; D. Rooney; G. Walker

2007-01-01

358

Thermodynamics of the alkaline transition in phytocyanins.  

PubMed

The thermodynamics of the alkaline transition which influences the spectral and redox properties of the type 1 copper center in phytocyanins has been determined spectroscopically. The proteins investigated include Rhus vernicifera stellacyanin, cucumber basic protein and its Met89Gln variant, and umecyanin, the stellacyanin from horseradish roots, along with its Gln95Met variant. The changes in reaction enthalpy and entropy within the protein series show partial compensatory behavior. Thus, the reaction free energy change (hence the pK (a) value) is rather variable. This indicates that species-dependent differences in reaction thermodynamics, although containing an important contribution from changes in the hydrogen-bonding network of water molecules in the hydration sphere of the protein (which feature enthalpy-entropy compensation), are to a large extent protein-based. The data for axial ligand variants are consistent with the hypothesis of a copper-binding His as the deprotonating residue responsible for this transition. PMID:17569996

Battistuzzi, Gianantonio; Bellei, Marzia; Dennison, Christopher; Di Rocco, Giulia; Sato, Katsuko; Sola, Marco; Yanagisawa, Sachiko

2007-06-15

359

Polyvinyl alcohol membranes as alkaline battery separators  

SciTech Connect

Polyvinyl alcohol (PVA) cross-linked with aldehyde reagents yields membranes that demonstrate properties that make them suitable for use as alkaline battery separators. Film properties can be controlled by the choice of cross-linker, cross-link density and the method of cross-linking. Three methods of cross-linking and their effects on film properties are discussed. Film properties can also be modified by using a copolymer of vinyl alcohol and acrylic acid as the base for the separator and cross-linking it similarly to the PVA. Fillers can be incorporated into the films to further modify film properties. Results of separator screening tests and cell tests for several variations of PBA films are discussed.

Sheibley, D.W.; Gonzalez-Sanabria, O.; Manzo, M.

1982-01-01

360

Thermochemistry of alkaline-earth phenoxides  

Microsoft Academic Search

The standard molar enthalpies of formation of some alkaline-earth metal phenoxides were determined by reaction–solution calorimetry. The results obtained at T=298.15K were as follows: ?fHm?[M(OR)2,cr]\\/kJ·mol-1=-(837.9±7.5)[Mg(OPh)2];?(837.4±7.2)[Ca(OPh)2];-(888.1±7.2)[Ca(O-2,6-Me2Ph)2],-(828.8±7.3)[Sr(OPh)2];-(808.6±7.3)[Ba(OPh)2];-(880.7±7.3)[Ba(O-2,6-Me2Ph)2]. Together with an appropriate Born–Haber cycle, these results allow the calculation of lattice energies for the [M(OR)2] compounds. The thermochemical radii of the anions OR? were obtained using the Kapustinskii equation and the lattice energies

Carla Hipólito; João Paulo Leal; Yanzhi Guo; Matthias Epple

2006-01-01

361

GEOCHEMISTRY: The Importance of Being Alkaline  

NSDL National Science Digital Library

Access to the article is free, however registration and sign-in are required. The earliest forms of "protolife" on Earth must have been able to reproduce and replicate; it is likely that they were also cellular. How might such systems have formed? In his Perspective, Russell highlights the report by Hanczyc et al., who show that clay particles can catalyze the formation of lipid vesicles. These particles also adsorb RNA. If the vesicles are forced to divide, RNA is distributed among the daughter vesicles. Similar conditions to those used in the experiments may have existed at mounds created by alkaline, hydrothermal seepages on the ancient ocean floor. However, instead of lipids, polypeptides formed from amino acids may have formed the first organic membranes.

Michael John Russell (Scottish Universities Environmental Research Centre;)

2003-10-24

362

DNA denaturation under freezing in alkaline medium.  

PubMed

It is generally accepted that DNA conserves its secondary structure after a freeze-thaw cycle. A negligible amount of degradation occurs after this procedure. Degradation becomes appreciable only after multiple cycles of freezing and thawing. In this study, we have found that a single freeze-thaw cycle in alkaline medium (pH>or=10.8) gives rise to denaturation of calf thymus DNA, although the melting temperature of intact DNA in the solution used for the freeze-thaw experiments is higher than 60 degrees C. The degree of denaturation is almost independent of the regime of freezing. The melting curve obtained after DNA is frozen at -2 degrees C and then thawed is almost the same as after a freezing carried out in liquid nitrogen (-196 degrees C). However, incubation in the same solution at 0 degrees C for 24 hours without freezing does not give rise to any denaturation. The degree of denaturation caused by freezing increases with pH (if pH>or=10.8) and decreases with Na2CO3 concentration at fixed pH and [Na+], although Na2CO3 decreases the melting temperature of intact DNA. A preliminary treatment of DNA with cisplatin or transplatin (0.01 Pt atoms per nucleotide) gives rise to a full recovery of the DNA secondary structure after freezing and thawing similar to what occurs after heating DNA to 100 degrees C and quick cooling. Possible mechanisms that may cause DNA denaturation during a freeze-thaw cycle in alkaline medium are discussed. PMID:19108591

Galyuk, Elena N; Wartell, Roger M; Dosin, Yury M; Lando, Dmitri Y

2009-02-01

363

Advanced alkaline water electrolysis. Task 2 summary report. Model for alkaline water electrolysis systems  

Microsoft Academic Search

Task 2 involved the establishment of an engineering and economic model for the evaluation of various options in water electrolysis. The mode, verification of the specific coding and four case studies are described. The model was tested by evaluation of a nearly commercial technology, i.e., an 80-kW alkaline electrolyte system, operating at 60°C, which delivers approximately 255 SLM, hydrogen for

M. R. Yaffe; J. N. Murray

1980-01-01

364

ChemTeacher: Alkaline Earth Metals = Group 2 (IIA)  

NSDL National Science Digital Library

ChemTeacher compiles background information, videos, articles, demonstrations, worksheets and activities for high school teachers to use in their classrooms. The Alkaline Earth Metals page includes resources for teaching students about the discovery, properties, and uses of the alkaline earth metals.

2011-01-01

365

Distribution of alkaline sphingomyelinase activity in human beings and animals  

Microsoft Academic Search

The alkaline sphingomyelinase (SMase) was first found in rat intestinal brush border. The important roles of this enzyme in digestion of sphingomyelin and in mucosal cell proliferation have been suggested. In the present work, the distribution of the alkaline SMase in the tissues of human beings and animals have been studied. By assaying the enzyme activity in human biopsy samples,

R.-D. Duan; E. Hertervig; L. Nyberg; T. Hauge; B. Sternby; J. Lillienau; A. Farooqi; Å. Nilsson

1996-01-01

366

Investigation of Alkaline Nature of Rain Water in India  

Microsoft Academic Search

Increased industrialization and urbanization lead to the atmospheric acidity which causes acid rain. However, in India, the nature of rain water has been observed to be alkaline. The reason for alkaline nature of rain water is found to be the buffering of acidity by soil-derived aerosols which are rich in Ca. Over the Indian Ocean where concentrations of soil dust

Umesh C. Kulshrestha; Monika J. Kulshrestha; R. Sekar; M. Vairamani; Ajit K. Sarkar; Danesh C. Parashar

2001-01-01

367

Mechanism of the Solution Oxidation of Rofecoxib Under Alkaline Conditions  

Microsoft Academic Search

Purpose. The rapid oxidation of rofecoxib under alkaline conditions has been previously reported. The oxidation was reported to involve g-lactone ring opening to an alcohol, which further oxidized to a dicarboxyclic acid. The oxidation was suspected to be mediated by peroxy radicals. This work further investigates the mechanism of oxidation under the alkaline solution conditions. Methods. The pH dependence of

Paul A. Harmon; Stephen Biffar; Steven M. Pitzenberger; Robert A. Reed

2005-01-01

368

Alkalinity regulation in soft-water Florida lakes  

SciTech Connect

Major ion chemistry data collected as part of the Environmental Protection Agency (EPA) Eastern Lake Survey was examined to evaluate the mechanisms and extent of alkalinity regulation in 37 undisturbed, soft-water lakes in Florida. Comparison of major ion-Cl ratios in atmospheric deposition and in lake water shows the reactions resulting in retention of sulfate and nitrate are the dominant sources of alkalinity; production of organic acids and ammonium retention are the major alkalinity-consuming processes. Based on average reactions, enrichment of major cations accounted for only 12% of net alkalinity generation in the study lakes. In general, calcium and potassium were depleted in low-ANC lakes, presumably by in-lake sinks, and were enriched in most higher ANC lakes by ground water inputs. Differences in alkalinity among these lakes reflect hydrologic factors and the proximity of clay and carbonate deposits to the lake bed. Overall, net-alkalinity generation nearly balanced H+ predicted from evaporative concentration of atmospheric acid inputs; the close balance suggests that the alkalinity status of these lakes is very sensitive to changes in atmospheric loadings and groundwater alkalinity inputs.

Baker, L.A.; Pollman, C.D.; Eilers, J.M.

1988-01-01

369

Testing and Evaluation of Primary Alkaline Cells and Batteries.  

National Technical Information Service (NTIS)

Testing and evaluating the performance of primary alkaline cells was completed. The cells are of the zinc-alkaline-mercuric oxide system-- the 1R, 12R, 42R, 502R, 625R, 640R, 650R, 1438R and 1450R cell-types. The reported areas of performance are: EMF ove...

R. Goodman

1967-01-01

370

ANNUAL REPORT. ACTINIDE-ALUMINATE SPECIATION IN ALKALINE RADIOACTIVE WASTE  

EPA Science Inventory

Highly alkaline radioactive waste tanks contain a number of transuranic species, in particular U, Np, Pu, and Am-the exact forms of which are currently unknown. Knowledge of actinide speciation under highly alkaline conditions is essential towards understanding and predicting the...

371

Performance of alkaline fuel cells: A possible future energy system?  

Microsoft Academic Search

Alkaline fuel cells (AFCs) are amongst the most mature fuel cell technologies having been in use since the mid 1960s by NASA in the Apollo and Space Shuttle programs. The AFC process is revisited to define current operating characteristics as the baseline for future developments of AFC technologies that can take advantage of advances in alkaline water electrolysers (AWEs). The

Betty Y. S. Lin; Donald W. Kirk; Steven J. Thorpe

2006-01-01

372

Removal of plutonium and americium from alkaline waste solutions  

DOEpatents

High salt content, alkaline waste solutions containing plutonium and americium are contacted with a sodium titanate compound to effect removal of the plutonium and americium from the alkaline waste solution onto the sodium titanate and provide an effluent having a radiation level of less than 10 nCi per gram alpha emitters.

Schulz, Wallace W. (Richland, WA)

1979-01-01

373

Expression of intestinal alkaline phosphatase in human organs  

Microsoft Academic Search

Human intestinal alkaline phosphatase was immunohistochemically identified and localized in the pancreas, liver and kidney by use of a monoclonal antibody specific for intestinal alkaline phosphatase isozyme and by amplified biotin-streptavidin staining. In all the examined organs, the intestinal isozyme was found to be localized in the epithelial cells of ducts: bile ducts in the liver, distal convoluted tubules and

Ulla Domar; Berith Nilsson; Vladimir Baranov; Ulf Gerdes; Torgny Stigbrand

1992-01-01

374

High alkaline phosphatase activity and growth in preterm neonates  

Microsoft Academic Search

In a study on 857 infants born preterm, high peak plasma alkaline phosphatase activity was independently related to slower growth rate in the neonatal period, and to a highly significant reduction in attained length at 9 months and 18 months post term. At 18 months the deficit in body length associated with peak neonatal plasma alkaline phosphase activity of 1200

A Lucas; O G Brooke; B A Baker; N Bishop; R Morley

1989-01-01

375

Hydrolysis and fractionation of lignocellulosic biomass  

DOEpatents

A multi-function process is described for the hydrolysis and fractionation of lignocellulosic biomass to separate hemicellulosic sugars from other biomass components such as extractives and proteins; a portion of the solubilized lignin; cellulose; glucose derived from cellulose; and insoluble lignin from said biomass comprising one or more of the following: optionally, as function 1, introducing a dilute acid of pH 1.0-5.0 into a continual shrinking bed reactor containing a lignocellulosic biomass material at a temperature of about 94 to about 160.degree. C. for a period of about 10 to about 120 minutes at a volumetric flow rate of about 1 to about 5 reactor volumes to effect solubilization of extractives, lignin, and protein by keeping the solid to liquid ratio constant throughout the solubilization process; as function 2, introducing a dilute acid of pH 1.0-5.0, either as virgin acid or an acidic stream from another function, into a continual shrinking bed reactor containing either fresh biomass or the partially fractionated lignocellulosic biomass material from function 1 at a temperature of about 94-220.degree. C. for a period of about 10 to about 60 minutes at a volumetric flow rate of about 1 to about 5 reactor volumes to effect solubilization of hemicellulosic sugars, semisoluble sugars and other compounds, and amorphous glucans by keeping the solid to liquid ratio constant throughout the solubilization process; as function 3, optionally, introducing a dilute acid of pH 1.0-5.0 either as virgin acid or an acidic stream from another function, into a continual shrinking bed reactor containing the partially fractionated lignocellulosic biomass material from function 2 at a temperature of about 180-280.degree. C. for a period of about 10 to about 60 minutes at a volumetric flow rate of 1 to about 5 reactor volumes to effect solubilization of cellulosic sugars by keeping the solid to liquid ratio constant throughout the solubilization process; and as function 4, optionally, introducing a dilute acid of pH 1.0-5.0 either as virgin acid or an acidic stream from another function, into a continual shrinking bed reactor containing the partially fractionated lignocellulosic biomass material from function 3 at a temperature of about 180-280.degree. C. for a period of about 10 to about 60 minutes at a volumetric flow rate of about 1 to about 5 reactor volumes to effect solubilization of cellulosic sugars by keeping the solid to liquid ratio constant throughout the solubilization process.

Torget, Robert W. (Littleton, CO); Padukone, Nandan (Denver, CO); Hatzis, Christos (Denver, CO); Wyman, Charles E. (Lakewood, CO)

2000-01-01

376

Kinetics of catalyzed hydrolysis of 4-methylumbelliferyl caprylate (MUCAP) salmonella reagent  

NASA Astrophysics Data System (ADS)

The kinetics of chemical hydrolysis including neutral, acid- and base-catalyzed hydrolysis of 4-methylumbelliferyl caprylate (MUCAP) salmonella reagent were studied at different temperatures. The rate constants and activation parameters were determined by following the build-up of fluorescence peak of the hydrolysis product 4-methylumbelliferone (4-MU). The time scale of esterase enzyme hydrolysis caused by salmonella was compared with chemical hydrolysis as a background process.

Al-Kady, Ahmed S.; Ahmed, El-Sadat I.; Gaber, M.; Hussein, Mohamed M.; Ebeid, El-Zeiny M.

2011-09-01

377

Hydrothermal treatment of C-N-O-H wastes: Reaction kinetics and pathways for hydrolysis products of high explosives  

SciTech Connect

Bench-scale studies demonstrated the efficacy of hydrothermal oxidation for the treatment of wastes derived from the alkaline hydrolysis of the high explosive PBX 9404 (94% HMX, 3% nitrocellulose, and 3% chloroethyl phosphate). Specifically, chemical kinetics studies were used to deduce major global reaction pathways, and to develop a kinetic model. Although the hydrolysis liquor is a complicated waste matrix, a three-parameter kinetic model captured major reaction paths. The kinetic model used total organic carbon (TOC) as a bulk parameter for dissolved organic materials, while NO{sub x}{sup {minus}} was used to represent the oxidized nitrogen species in solution (NO{sub 2}{sup {minus}} and NO{sub 3}{sup {minus}}). With the use of the kinetic model, an optimal treatment strategy using two oxidation stages was derived. The first stage involved balancing NO{sub x}{sup {minus}} and O{sub 2} redox chemistry to minimize aqueous nitrogen in the effluent, while the second stage mineralized the remaining TOC.

Dell'Orco, P.; Eaton, E.; McInroy, R.; Flesner, R.; Walker, T.; Muske, K.

1999-12-01

378

Hydrolysis of N-Alkyl Sulfamates and the Catalytic Efficiency of an S-N Cleaving Sulfamidase  

PubMed Central

The final step in the degradation of heparin sulfate involves the enzymatic hydrolysis of its 2-sulfamido groups. To evaluate the power of the corresponding sulfamidases as catalysts, we examined the reaction of N-neopentyl sulfamate at elevated temperatures and found it to undergo specific acid catalyzed hydrolysis even at alkaline pH. A rate constant of 10?16 s?1 was calculated using the Eyring equation for water attack on the N-protonated species at pH 7, 25 °C. As a model for the pH neutral reaction, a rate constant for hydroxide attack on (CH3)3CCH2N+H2SO3? at pH 7, 25 °C was calculated to be 10?19 s?1. The corresponding rate enhancement (kcat/knon) produced by the N-sulfamidase of F. heparinum is approximately 1016-fold, which is somewhat larger than those generated by most hydrolytic enzymes but considerably smaller than those generated by S-O cleaving sulfatases.

Lohman, Danielle C.; Wolfenden, Richard; Edwards, David R.

2012-01-01

379

Hydrolysis of N-alkyl sulfamates and the catalytic efficiency of an S-N cleaving sulfamidase.  

PubMed

The final step in the degradation of heparin sulfate involves the enzymatic hydrolysis of its 2-sulfamido groups. To evaluate the power of the corresponding sulfamidases as catalysts, we examined the reaction of N-neopentyl sulfamate at elevated temperatures and found it to undergo specific acid catalyzed hydrolysis even at alkaline pH. A rate constant of 10(-16) s(-1) was calculated using the Eyring equation for water attack on the N-protonated species at pH 7, 25 °C. As a model for the pH neutral reaction, a rate constant for hydroxide attack on (CH(3))(3)CCH(2)N(+)H(2)SO(3)(-) at pH 7, 25 °C was calculated to be 10(-19) s(-1). The corresponding rate enhancement (k(cat)/k(non)) produced by the N-sulfamidase of F. heparinum is approximately 10(16)-fold, which is somewhat larger than those generated by most hydrolytic enzymes but considerably smaller than those generated by S-O cleaving sulfatases. PMID:22352783

Lohman, Danielle C; Wolfenden, Richard; Edwards, David R

2012-02-29

380

Proteoliposomes Harboring Alkaline Phosphatase and Nucleotide Pyrophosphatase as Matrix Vesicle Biomimetics*  

PubMed Central

We have established a proteoliposome system as an osteoblast-derived matrix vesicle (MV) biomimetic to facilitate the study of the interplay of tissue-nonspecific alkaline phosphatase (TNAP) and NPP1 (nucleotide pyrophosphatase/phosphodiesterase-1) during catalysis of biomineralization substrates. First, we studied the incorporation of TNAP into liposomes of various lipid compositions (i.e. in pure dipalmitoyl phosphatidylcholine (DPPC), DPPC/dipalmitoyl phosphatidylserine (9:1 and 8:2), and DPPC/dioctadecyl-dimethylammonium bromide (9:1 and 8:2) mixtures. TNAP reconstitution proved virtually complete in DPPC liposomes. Next, proteoliposomes containing either recombinant TNAP, recombinant NPP1, or both together were reconstituted in DPPC, and the hydrolysis of ATP, ADP, AMP, pyridoxal-5?-phosphate (PLP), p-nitrophenyl phosphate, p-nitrophenylthymidine 5?-monophosphate, and PPi by these proteoliposomes was studied at physiological pH. p-Nitrophenylthymidine 5?-monophosphate and PLP were exclusively hydrolyzed by NPP1-containing and TNAP-containing proteoliposomes, respectively. In contrast, ATP, ADP, AMP, PLP, p-nitrophenyl phosphate, and PPi were hydrolyzed by TNAP-, NPP1-, and TNAP plus NPP1-containing proteoliposomes. NPP1 plus TNAP additively hydrolyzed ATP, but TNAP appeared more active in AMP formation than NPP1. Hydrolysis of PPi by TNAP-, and TNAP plus NPP1-containing proteoliposomes occurred with catalytic efficiencies and mild cooperativity, effects comparable with those manifested by murine osteoblast-derived MVs. The reconstitution of TNAP and NPP1 into proteoliposome membranes generates a phospholipid microenvironment that allows the kinetic study of phosphosubstrate catabolism in a manner that recapitulates the native MV microenvironment.

Simao, Ana Maria S.; Yadav, Manisha C.; Narisawa, Sonoko; Bolean, Mayte; Pizauro, Joao Martins; Hoylaerts, Marc F.; Ciancaglini, Pietro; Millan, Jose Luis

2010-01-01

381

Hydrolysis of ozone pretreated energy grasses for optimal fermentable sugar production.  

PubMed

Ozonated energy grass varieties were enzymatically hydrolyzed to establish process parameters for maximum fermentable sugar production. Conditions for ozonolysis were selected on the basis of maximum delignification and glucan retention after pretreatment. To study the effect of lignin degradation products generated during ozonolysis on cellulolytic enzymes, hydrolysis was carried out for washed and unwashed pretreated solids. Washing the solids significantly (p<0.05) enhanced glucan conversion from 34.3% to 100% while delivering glucose yields of 146.2-431.9mg/g biomass. Highest fermentable sugars were produced when grasses were ozonated for maximum delignification and washed solids were hydrolyzed using 0.1g/g Cellic® CTec2. In a comparative study on alkaline pretreatment with 1% NaOH for 60min, Saccharum arundinaceum exhibited the highest glucan conversion with maximum sugar production of 467.9mg/g. Although ozonolysis is an effective and environmentally friendly technique for cellulosic sugar production, process optimization is needed to ascertain economic feasibility of the process. PMID:24045197

Panneerselvam, Anushadevi; Sharma-Shivappa, Ratna R; Kolar, Praveen; Clare, Debra A; Ranney, Thomas

2013-08-26

382

STIMULATION OF MICROBIAL UREA HYDROLYSIS IN GROUNDWATER TO ENHANCE CALCITE PRECIPITATION  

SciTech Connect

Sequential addition of molasses and urea was tested as a means of stimulating microbial urea hydrolysis in the Eastern Snake River Plain Aquifer in Idaho. Ureolysis is an integral component of a novel remediation approach for divalent trace metal and radionuclide contaminants in groundwater and associated geomedia, where the contaminants are immobilized by coprecipitation in calcite. The generation of carbonate alkalinity from ureolysis promotes calcite precipitation. In calcite-saturated aquifers, this represents a potential long-term contaminant sequestration mechanism. In a single well experiment, dilute molasses was injected three times over two weeks to promote overall microbial growth, followed by one urea injection. With molasses addition, total cell numbers in the groundwater increased one to two orders of magnitude. Estimated ureolysis rates in recovered groundwater samples increased from <0.1 nmol L-1 hr-1 to >25 nmol L-1 hr-1. A quantitative PCR assay for the bacterial ureC gene indicated that urease gene numbers increased up to 170 times above pre-injection levels. Following urea injection, calcite precipitates were recovered. Estimated values for an in situ first order ureolysis rate constant ranged from 0.016 to 0.057 day-1. The results are promising with respect to the potential to manipulate in situ biogeochemical processes to promote contaminant sequestration.

Yoshiko Fujita; Joanna L. Taylor; Tina L. Gresham; Mark E. Delwiche; Frederick S. Colwell; Travis McLing; Lynn Petzke; Robert W. Smith

2008-04-01

383

Batteries: from alkaline to zinc-air.  

PubMed

There is no perfect disposable battery--one that will sit on the shelf for 20 years, then continually provide unlimited current, at a completely constant voltage until exhausted, without producing heat. There is no perfect rechargeable battery--one with all of the above characteristics and will also withstand an infinite overcharge while providing an equally infinite cycle life. There are only compromises. Every battery selection is a compromise between the ideally required characteristics, the advantages, and the limitations of each battery type. General selection of a battery type to power a medical device is largely outside the purview of the biomed. Initially, these are engineering decisions made at the time of medical equipment design and are intended to be followed in perpetuity. However, since newer cell types evolve and the manufacturer's literature is fixed at the time of printing, some intelligent substitutions may be made as long as the biomed understands the characteristics of both the recommended cell and the replacement cell. For example, when the manufacturer recommends alkaline, it is usually because of the almost constant voltage it produces under the devices' design load. Over time, other battery types may be developed that will meet the intent of the manufacturer, at a lower cost, providing longer operational life, at a lower environmental cost, or with a combination of these advantages. In the Obstetrical Doppler cited at the beginning of this article, the user had put in carbon-zinc cells, and the biomed had unknowingly replaced them with carbonzinc cells. If the alkaline cells recommended by the manufacturer had been used, there would have been the proper output voltage at the battery terminals when the [table: see text] cells were at their half-life. Instead, the device refused to operate since the battery voltage was below presumed design voltage. While battery-type substitutions may be easily and relatively successfully made in disposable applications (for example, zinc-air for alkaline--if it is cost-effective), this is absolutely forbidden for secondary cells. Because of the differing cell voltages, charge characteristics and overcharge tolerance between different types of secondary cells, substituting a nickel-cadmium battery pack for the more expensive lithium-ion pack (if it is physically able to fit into the battery compartment), might appear to save money (e.g. $50 vs. $100) but it would be very ill advised. Since the cell characteristics are very different, it would be downright fatal to anyone within the 'kill radius' when the pack explodes. Those outside the kill radius would receive chemical burns from the electrolyte. Substitutions of secondary cell battery packs are generally not a good idea for biomeds to engage in. These are engineering decisions best left to either aftermarket battery pack manufacturers or the medical device manufacturer as a design engineering change. PMID:15106428

Dondelinger, Robert M

384

A mechanistic model of the enzymatic hydrolysis of cellulose.  

PubMed

A detailed mechanistic model of enzymatic cellulose hydrolysis has been developed. The behavior of individual cellulase enzymes and parameters describing the cellulose surface properties are included. Results obtained for individual enzymes (T. reesei endoglucanase 2 and cellobiohydrolase I) and systems with both enzymes present are compared with experimental literature data. The model was sensitive to cellulase-accessible surface area; the EG2-CBHI synergy observed experimentally was only predicted at a sufficiently high cellulose surface area. Enzyme crowding, which is more apparent at low surface areas, resulted in differences between predicted and experimental rates of hydrolysis. Model predictions also indicated that the observed decrease in hydrolysis rates following the initial rate of rapid hydrolysis is not solely caused by product inhibition and/or thermal deactivation. Surface heterogeneities, which are not accounted for in this work, may play a role in decreasing the hydrolysis rate. The importance of separating the enzyme adsorption and complexation steps is illustrated by the model's sensitivity to the rate of formation of enzyme-substrate complexes on the cellulose surface. PMID:20506540

Levine, Seth E; Fox, Jerome M; Blanch, Harvey W; Clark, Douglas S

2010-09-01

385

N-phenylglucosylamine hydrolysis: a mechanistic probe of ?-glucosidase.  

PubMed

The spontaneous hydrolysis of glycosylamines, where the aglycone is either a primary amine or ammonia, is over a hundred million-times faster than that of O- or S-glycosides. The reason for this (as pointed out by Capon and Connett in 1965) is that, in contrast to the mechanism for O- or S-glycoside hydrolysis, hydrolysis of these N-glycosides (e.g., glc-NHR) involves an endocyclic C-O bond cleavage resulting in formation of an imine (iminium ion) which then reacts with water. Since ring-opening is kinetically favored with glycosylamines, compounds such as phenylglucosylamine can be a useful probes of enzymes that have been suggested to possibly follow this mechanism. With ?-glucosidase from sweet almonds, the enzyme is highly efficient in catalyzing the hydrolysis of phenyl glucoside (k(cat)/k(non)?10(14)) and phenyl thioglucoside (k(cat)/k(non)?10(10)) while with either the almond or the Aspergillus niger enzyme or with yeast ?-glucosidase, there is no detectable catalysis of phenylglucosylamine hydrolysis (k(cat)/k(non)<20). These results are consistent with the generally accepted mechanism involving exocyclic bond cleavage by these enzymes. PMID:21435675

Na, Ying; Shen, Hong; Byers, Larry D

2011-03-23

386

Enzymatic hydrolysis of fractionated products from oil thermally oxidated  

SciTech Connect

Enzymatic hydrolysis of the acylglycerol products obtained from thermally oxidized vegetable oils was studied. Corn, sunflower and soybean oils were heated in the laboratory at 180/sup 0/C for 50, 70 and 100 hr with aeration and directly fractionated by silicic acid column chromatography. By successive elution with 20%, then 60% isopropyl ether in n-hexane, and diethyl ether, the thermally oxidized oils were separated into three fractions: the nonpolar fraction (monomeric compounds), slightly polar fraction (dimeric compounds), and polar fraction comprising oligomeric compounds. Enzymatic hydrolysis with pancreatic lipase showed that the monomers were hydrolyzed as rapidly as the corresponding unheated oils, the dimers much more slowly, and the oligomeric compounds barely at all. Overall, the hydrolysis of the dimers was less than 23% of that for the monomers, with small differences among the oils. Longer heating periods resulted in greater reductions in hydrolysis of the dimeric compounds. These results suggest that the degree of enzymatic hydrolysis of the fractionated acylglycerol compounds is related to differences in the thermal oxidative deterioration, and amounts of polar compounds in the products. (33 Refs.)

Yashida, H.; Alexander, J.C.

1983-01-01

387

Fluoride incorporation into apatite crystals delays amelogenin hydrolysis  

PubMed Central

Enamel fluorosis has been related to an increase in the amount of amelogenin in fluorosed enamel as compared to normal enamel in the maturation stage. In this study we tested the hypothesis that fluoride incorporated into carbonated apatite alters amelogenin hydrolysis. Recombinant human amelogenin (rh174) was allowed to bind to 0.15 mg of carbonated hydroxyapatite (CAP) or fluoride-containing carbonated hydroxyapatite (F-CAP) synthesized to contain 100, 1000 or 4000 ppm F-. After 3 h digestion with recombinant human MMP20 or KLK4, bound protein was characterized by reverse-phase HPLC. Proteolytic fragments formed after 24 h digestion of amelogenin, were identified by LC tandem mass spectrometry (LCMS/MS). The hydrolysis of amelogenin bound to F100-CAP by both MMP20 and KLK4 was significantly reduced in a dose dependent manner as compared to CAP. After 24 h hydrolysis, the number of cleavage sites in bound amelogenin by MMP20 were similar in CAP and F100-CAP, whereas there were 24 fewer cleavage sites identified for the KLK4 hydrolysis on F100-CAP as compared to CAP. These results suggest that the reduced hydrolysis of amelogenins in fluorosed enamel may be partially due to the increased fluoride content in fluoride containing apatite, contributing to the hypomineralized enamel matrix phenotype observed in fluorosed enamel.

DenBesten, Pamela; Zhu, Li; Li, Wu; Tanimoto, Kotaro; Liu, Haichuan; Witkowska, Halina Ewa

2012-01-01

388

Characterization of casein hydrolysates derived from enzymatic hydrolysis  

PubMed Central

Background Casein is the main proteinaceous component of milk and has made us interest due to its wide applications in the food, drug, and cosmetic industries as well as to its importance as an investigation material for elucidating essential questions regarding the protein chemistry. Enzymatic hydrolysis is an important method commonly used in the modification of protein structure in order to enhance the functional properties of proteins. The relationship between enzymatic hydrolysis and structure change of casein need to make more study. Results During hydrolysis, degree of hydrolysis in the casein hydrolysates increased rapidly in the initial 20 minutes, reached a plateau after 45 minutes, and then kept relative constant for the rest of the hydrolysis. The relative percentage of the released peptides with molecular weight of over 50 kD significantly decreased with hydrolyzation, while those with MW of 30–50 kD and below 20 kD increased significantly. The contents of a-helix and ?-turn in the hydrolysates increased compared to the original casein. Moreover, the molecular flexibilities of the casein hydrolysates, estimated by the ratio of ?-helix to ?-structure, were lower than that of original casein protein. Conclusions The significant changes in molecular weight distribution and structure characteristics of casein hydrolysates were found compared to the control sample. This change should be the basis of enhancement of functional properties.

2013-01-01

389

Enzymatic hydrolysis of cellulose and various pretreated wood fractions  

SciTech Connect

Three strains of Trichoderma-Trichoderma reesei C30, Trichoderma reesei QM9414, and Trichoderma species E58-were used to study the enzymatic hydrolysis of pretreated wood substrates. Each of the culture filtrates was incubated with a variety of commercially prepared cellulose substrates and pretreated wood substrates. Solka floc was the most easily degraded commercial cellulose. The enzyme accessibility of steam-exploded samples which has been alkali extracted and then stored wet decreased with the duration of the steam treatment. Air drying reduced the extent of hydrolysis of all the samples but had a greater effect on the samples which had previously shown the greatest hydrolysis. Mild pulping using 2% chlorite increased the enzymatic hydrolysis of all the samples. Steam explosion was shown to be an excellent pretreatment method for aspen wood and was much superior to dilute nitric acid pretreatment. The results indicate that the distribution of the lignin as well as the surface area of the cellulosic substrate are important features in enzymatic hydrolysis. (Refs 17).

Saddler, J.N.; Brownell, H.H.; Clermont, L.P.; Levitin, N.

1982-06-01

390

Combination of alkaline and microwave pretreatment for disintegration of meat processing wastewater sludge.  

PubMed

Meat processing wastewater sludge has high organic content but it is very slow to degrade in biological processes. Anaerobic digestion may be a good alternative for this type of sludge when the hydrolysis, known to be the rate-limiting step of biological sludge anaerobic degradation, could be eliminated by disintegration. This investigation deals with disintegration of meat processing wastewater sludge. Microwave (MW) irradiation and combined alkaline pretreatment and MW irradiation were applied to sludge for disintegration purposes. Disintegration performance of the methods was evaluated with disintegration degree based on total and dissolved organic carbon calculations (DD(TOC)), and the solubilization of volatile solids (S(VS)) in the pretreated sludge. Optimum conditions were found to be 140 degrees C and 30 min for MW irradiation using response surface methodology (RSM) and pH = 13 for combined pretreatment. While DD(TOC) was observed as 24.6% and 54.9, S(VS) was determined as 8.54% and 42.5% for MW pretreated and combined pretreated sludge, respectively. The results clearly show that pre-conditioning of sludge with alkaline pretreatment played an important role in enhancing the disintegration efficiency of subsequent MW irradiation. Disintegration methods also affected the anaerobic biodegradability and dewaterability of sludge. An increase of 23.6% in biogas production in MW irradiated sludge was obtained, comparing to the raw sludge at the end of the 35 days of incubation. This increase was observed as 44.5% combined pretreatment application. While MW pretreatment led to a little improvement of the dewatering performance of sludge, in combined pretreatment NaOH deteriorates the sludge dewaterability. PMID:23837322

Erden, G

391

Reduced activity of alkaline phosphatase due to host-guest interactions with humic superstructures.  

PubMed

Nuclear Magnetic Resonance (NMR) spectroscopy was applied to directly study the interactions between the alkaline phosphatase enzyme (AP) and two different humic acids from a volcanic soil (HA-V) and a Lignite deposit (HA-L). Addition of humic matter to enzyme solutions caused signals broadening in (1)H-NMR spectra, and progressive decrease and increase of enzyme relaxation (T1 and T2) and correlation (?C) times, respectively. Spectroscopic changes were explained with formation of ever larger weakly-bound humic-enzyme complexes, whose translational and rotational motion was increasingly restricted. NMR diffusion experiments also showed that the AP diffusive properties were progressively reduced with formation of large humic-enzyme complexes. The more hydrophobic HA-L affected spectral changes more than the more hydrophilic HA-V. (1)H-NMR spectra also showed the effect of progressively greater humic-enzyme complexes on the hydrolysis of an enzyme substrate, the 4-nitrophenyl phosphate disodium salt hexahydrate (p-NPP). While AP catalysis concomitantly decreased NMR signals of p-NPP and increased those of nitrophenol, addition of humic matter progressively and significantly slowed down the rate of change for these signals. In agreement with the observed spectral changes, the AP catalytic activity was more largely inhibited by HA-L than by HA-V. Contrary to previous studies, in which humic-enzyme interactions were only indirectly assumed from changes in spectrophotometric behavior of enzyme substrates, the direct measurements of AP behavior by NMR spectroscopy indicated that humic materials formed weakly-bound host-guest complexes with alkaline phosphatase, and the enzyme catalytic activity was thereby significantly inhibited. These results suggest that the role of extracellular enzymes in soils may be considerably reduced when they come in contact with organic matter dissolved in the soil solution. PMID:23953249

Mazzei, Pierluigi; Oschkinat, Hartmut; Piccolo, Alessandro

2013-08-13

392

Effects of acidity and alkalinity on the stability of amidohydrolases in freshwater  

SciTech Connect

The influence of acidity and alkalinity on the enzymatic hydrolysis of amide-N in the aquatic system was investigated by determining the stability of L-asparaginase (EC (Enzyme Commission) 3.5.1.1), L-glutaminase (EC 3.5.1.2), and amidase (EC 3.5.1.4), and urease (EC 3.5.1.5) with respect to pH in three freshwater lakes. The water samples were first incubated at the indicated buffer pH (1-13) for 24 h; then each enzyme was assayed at its optimal pH (pH/sub opt/) under standardized conditions. L-Asparaginase retained essentially 100% of its activity within the pH range of 6-7 in Lake Evans and Lake Matthews, and 5-7 in Lake Perris. L-Glutaminase was active between pH 6 and 7 in the water samples surveyed. Amidase remained completely active at pH ranges of 4-8 in Lake Evans, 4-7 in Lake Matthews, and 5-8 in Lake Perris. Urease remained active over a broad pH range of 5-9 in Lake Evans, 5-8 in Lake Matthews, and 4-8 in Lake Perris. There was a progressive loss in enzyme activity below and above these pH ranges. The results suggest that the decline in aquatic amidohydrolase activities in relation to the pH-profile near their pH/sub opt/ was caused by a reversible reaction involving the ionization or deionization of functional groups of the active center of the protein, but under highly acidic or alkaline conditions (pH <4 to >9) the reduced activitiy appears to be due to irreversible inactivation of the enzyme.

Frankenberger, W.T. Jr.; Page, A.L.

1983-01-01

393

Microbial thiocyanate utilization under highly alkaline conditions.  

PubMed

Three kinds of alkaliphilic bacteria able to utilize thiocyanate (CNS-) at pH 10 were found in highly alkaline soda lake sediments and soda soils. The first group included obligate heterotrophs that utilized thiocyanate as a nitrogen source while growing at pH 10 with acetate as carbon and energy sources. Most of the heterotrophic strains were able to oxidize sulfide and thiosulfate to tetrathionate. The second group included obligately autotrophic sulfur-oxidizing alkaliphiles which utilized thiocyanate nitrogen during growth with thiosulfate as the energy source. Genetic analysis demonstrated that both the heterotrophic and autotrophic alkaliphiles that utilized thiocyanate as a nitrogen source were related to the previously described sulfur-oxidizing alkaliphiles belonging to the gamma subdivision of the division Proteobacteria (the Halomonas group for the heterotrophs and the genus Thioalkalivibrio for autotrophs). The third group included obligately autotrophic sulfur-oxidizing alkaliphilic bacteria able to utilize thiocyanate as a sole source of energy. These bacteria could be enriched on mineral medium with thiocyanate at pH 10. Growth with thiocyanate was usually much slower than growth with thiosulfate, although the biomass yield on thiocyanate was higher. Of the four strains isolated, the three vibrio-shaped strains were genetically closely related to the previously described sulfur-oxidizing alkaliphiles belonging to the genus Thioalkalivibrio. The rod-shaped isolate differed from the other isolates by its ability to accumulate large amounts of elemental sulfur inside its cells and by its ability to oxidize carbon disulfide. Despite its low DNA homology with and substantial phenotypic differences from the vibrio-shaped strains, this isolate also belonged to the genus Thioalkalivibrio according to a phylogenetic analysis. The heterotrophic and autotrophic alkaliphiles that grew with thiocyanate as an N source possessed a relatively high level of cyanase activity which converted cyanate (CNO-) to ammonia and CO2. On the other hand, cyanase activity either was absent or was present at very low levels in the autotrophic strains grown on thiocyanate as the sole energy and N source. As a result, large amounts of cyanate were found to accumulate in the media during utilization of thiocyanate at pH 10 in batch and thiocyanate-limited continuous cultures. This is a first direct proof of a "cyanate pathway" in pure cultures of thiocyanate-degrading bacteria. Since it is relatively stable under alkaline conditions, cyanate is likely to play a role as an N buffer that keeps the alkaliphilic bacteria safe from inhibition by free ammonia, which otherwise would reach toxic levels during dissimilatory degradation of thiocyanate. PMID:11157213

Sorokin, D Y; Tourova, T P; Lysenko, A M; Kuenen, J G

2001-02-01

394

Microbial Thiocyanate Utilization under Highly Alkaline Conditions  

PubMed Central

Three kinds of alkaliphilic bacteria able to utilize thiocyanate (CNS?) at pH 10 were found in highly alkaline soda lake sediments and soda soils. The first group included obligate heterotrophs that utilized thiocyanate as a nitrogen source while growing at pH 10 with acetate as carbon and energy sources. Most of the heterotrophic strains were able to oxidize sulfide and thiosulfate to tetrathionate. The second group included obligately autotrophic sulfur-oxidizing alkaliphiles which utilized thiocyanate nitrogen during growth with thiosulfate as the energy source. Genetic analysis demonstrated that both the heterotrophic and autotrophic alkaliphiles that utilized thiocyanate as a nitrogen source were related to the previously described sulfur-oxidizing alkaliphiles belonging to the gamma subdivision of the division Proteobacteria (the Halomonas group for the heterotrophs and the genus Thioalkalivibrio for autotrophs). The third group included obligately autotrophic sulfur-oxidizing alkaliphilic bacteria able to utilize thiocyanate as a sole source of energy. These bacteria could be enriched on mineral medium with thiocyanate at pH 10. Growth with thiocyanate was usually much slower than growth with thiosulfate, although the biomass yield on thiocyanate was higher. Of the four strains isolated, the three vibrio-shaped strains were genetically closely related to the previously described sulfur-oxidizing alkaliphiles belonging to the genus Thioalkalivibrio. The rod-shaped isolate differed from the other isolates by its ability to accumulate large amounts of elemental sulfur inside its cells and by its ability to oxidize carbon disulfide. Despite its low DNA homology with and substantial phenotypic differences from the vibrio-shaped strains, this isolate also belonged to the genus Thioalkalivibrio according to a phylogenetic analysis. The heterotrophic and autotrophic alkaliphiles that grew with thiocyanate as an N source possessed a relatively high level of cyanase activity which converted cyanate (CNO?) to ammonia and CO2. On the other hand, cyanase activity either was absent or was present at very low levels in the autotrophic strains grown on thiocyanate as the sole energy and N source. As a result, large amounts of cyanate were found to accumulate in the media during utilization of thiocyanate at pH 10 in batch and thiocyanate-limited continuous cultures. This is a first direct proof of a “cyanate pathway” in pure cultures of thiocyanate-degrading bacteria. Since it is relatively stable under alkaline conditions, cyanate is likely to play a role as an N buffer that keeps the alkaliphilic bacteria safe from inhibition by free ammonia, which otherwise would reach toxic levels during dissimilatory degradation of thiocyanate.

Sorokin, Dimitry Y.; Tourova, Tatyana P.; Lysenko, Anatoly M.; Kuenen, J. Gijs

2001-01-01

395

40 CFR 721.4668 - Hydrated alkaline earth metal salts of metalloid oxyanions.  

Code of Federal Regulations, 2010 CFR

...2010-07-01 false Hydrated alkaline earth metal salts of metalloid oxyanions...Substances § 721.4668 Hydrated alkaline earth metal salts of metalloid oxyanions...substance identified as hydrated alkaline earth metal salts of metalloid...

2010-07-01

396

40 CFR 721.4668 - Hydrated alkaline earth metal salts of metalloid oxyanions.  

Code of Federal Regulations, 2010 CFR

...2009-07-01 false Hydrated alkaline earth metal salts of metalloid oxyanions...Substances § 721.4668 Hydrated alkaline earth metal salts of metalloid oxyanions...substance identified as hydrated alkaline earth metal salts of metalloid...

2009-07-01

397

Solubility of pllutonium in alkaline salt solutions  

SciTech Connect

Plutonium solubility data from several studies have been evaluated. For each data set, a predictive model has been developed where appropriate. In addition, a statistical model and corresponding prediction intervals for plutonium solubility as a quadratic function of the hydroxide concentration have been developed. Because of the wide range of solution compositions, the solubility of plutonium can vary by as much as three orders of magnitude for any given hydroxide concentration and still remain within the prediction interval. Any nuclear safety assessments that depend on the maximum amount of plutonium dissolved in alkaline salt solutions should use concentrations at least as great as the upper prediction limits developed in this study. To increase the confidence in the prediction model, it is recommended that additional solubility tests be conducted at low hydroxide concentrations and with all of the other solution components involved. To validate the model for application to actual waste solutions, it is recommended that the plutonium solubilities in actual waste solutions be determined and compared to the values predicted by the quadratic model.

Hobbs, D.T.; Edwards, T.B.

1993-02-26

398

Low pH alkaline chemical formulations  

SciTech Connect

This report describes the development of a surfactant-enhanced alkaline flooding system that is applicable to specific reservoir conditions in Wilmington (California) field. The cost of the chemicals for an ASP (alkali/surfactant/polymer) flood is calculated to be $3.90/bbl of oil produced, with 78% of that cost attributable to polymer. This research included phase behavior tests, oil displacement tests, mineral dissolution tests, and adsorption measurements. It was discovered that consumption of low pH alkalis is low enough in the Wilmington field to be acceptable. In addition, alkali dramatically reduced surfactant adsorption and precipitation. A mixture of NaHCO3 and Na2CO3 was recommended for use as a preflush and in the ASP formulation. Research was also conducted on the synergistic effect that occurs when a mixture of alkali and synthetic surfactant contacts crude oil. It appears that very low IFT is predominantly a result of the activation of the natural surfactants present in the Wilmington oil, and the sustained low IFT is primarily the result of the synthetic surfactant. It also appears that removal of acids from the crude oil by the alkali renders the oil more interfacially reactive to synthetic surfactant. These phenomena help to explain the synergism that results from combining alkali and synthetic surfactant into a single oil recovery formulation. 19 refs., 24 figs., 10 tabs.

French, T.R.; Peru, D.A.; Thornton, S.D.

1989-01-01

399

Response of Desulfovibrio vulgaris to Alkaline Stress  

SciTech Connect

The response of exponentially growing Desulfovibrio vulgarisHildenborough to pH 10 stress was studied using oligonucleotidemicroarrays and a study set of mutants with genes suggested by microarraydata to be involved in the alkaline stress response deleted. The datashowed that the response of D. vulgaris to increased pH is generallysimilar to that of Escherichia coli but is apparently controlled byunique regulatory circuits since the alternative sigma factors (sigma Sand sigma E) contributing to this stress response in E. coli appear to beabsent in D. vulgaris. Genes previously reported to be up-regulated in E.coli were up-regulated in D. vulgaris; these genes included three ATPasegenes and a tryptophan synthase gene. Transcription of chaperone andprotease genes (encoding ATP-dependent Clp and La proteases and DnaK) wasalso elevated in D. vulgaris. As in E. coli, genes involved in flagellumsynthesis were down-regulated. The transcriptional data also identifiedregulators, distinct from sigma S and sigma E, that are likely part of aD. vulgaris Hildenborough-specific stress response system.Characterization of a study set of mutants with genes implicated inalkaline stress response deleted confirmed that there was protectiveinvolvement of the sodium/proton antiporter NhaC-2, tryptophanase A, andtwo putative regulators/histidine kinases (DVU0331 andDVU2580).

Stolyar, S.; He, Q.; He, Z.; Yang, Z.; Borglin, S.E.; Joyner, D.; Huang, K.; Alm, E.; Hazen, T.C.; Zhou, J.; Wall, J.D.; Arkin, A.P.; Stahl, D.A.

2007-11-30

400

Process for treating alkaline wastes for vitrification  

DOEpatents

A process is described for treating alkaline wastes for vitrification. The process involves acidifying the wastes with an oxidizing agent such as nitric acid, then adding formic acid as a reducing agent, and then mixing with glass formers to produce a melter feed. The nitric acid contributes nitrates that act as an oxidant to balance the redox of the melter feed, prevent reduction of certain species to produce conducting metals, and lower the pH of the wastes to a suitable level for melter operation. The formic acid reduces mercury compounds to elemental mercury for removal by steam stripping, and MnO{sub 2} to the Mn(II) ion to prevent foaming of the glass melt. The optimum amounts of nitric acid and formic acid are determined in relation to the composition of the wastes, including the concentrations of mercury (II) and MnO{sub 2}, noble metal compounds, nitrates, formates and so forth. The process minimizes the amount of hydrogen generated during treatment, while producing a redox-balanced feed for effective melter operation and a quality glass product. 4 figs.

Hsu, C.L.W.

1995-07-25

401

Process for treating alkaline wastes for vitrification  

DOEpatents

A process for treating alkaline wastes for vitrification. The process involves acidifying the wastes with an oxidizing agent such as nitric acid, then adding formic acid as a reducing agent, and then mixing with glass formers to produce a melter feed. The nitric acid contributes nitrates that act as an oxidant to balance the redox of the melter feed, prevent reduction of certain species to produce conducting metals, and lower the pH of the wastes to a suitable level for melter operation. The formic acid reduces mercury compounds to elemental mercury for removal by steam stripping, and MnO.sub.2 to the Mn(II) ion to prevent foaming of the glass melt. The optimum amounts of nitric acid and formic acid are determined in relation to the composition of the wastes, including the concentrations of mercury (II) and MnO.sub.2, noble metal compounds, nitrates, formates and so forth. The process minimizes the amount of hydrogen generated during treatment, while producing a redox-balanced feed for effective melter operation and a quality glass product.

Hsu, Chia-lin W. (Augusta, GA)

1995-01-01

402

Structural dissection of alkaline-denatured pepsin  

PubMed Central

It has been established in a number of studies that the alkaline-denatured state of pepsin (the IP state) is composed of a compact C-terminal lobe and a largely unstructured N-terminal lobe. In the present study, we have investigated the residual structure in the IP state in more detail, using limited proteolysis to isolate and characterize a tightly folded core region from this partially denatured pepsin. The isolated core region corresponds to the 141 C-terminal residues of the pepsin molecule, which in the fully native state forms one of the two lobes of the structure. A comparative study using NMR and CD spectroscopy has revealed, however, that the N-terminal lobe contributes a substantial amount of additional residual structure to the IP state of pepsin. CD spectra indicate in addition that significant nonnative ?-helical structure is present in the C-terminal lobe of the structure when the N-terminal lobe of pepsin is either unfolded or removed by proteolysis. This study demonstrates that the structure of pepsin in the IP state is significantly more complex than that of a fully folded C-terminal lobe connected to an unstructured N-terminal lobe.

Kamatari, Yuji O.; Dobson, Christopher M.; Konno, Takashi

2003-01-01

403

GTP and cytosol stimulate phosphoinositide hydrolysis in isolated platelet membranes  

SciTech Connect

Hydrolysis of polyphosphoinositides by phospholipase C was examined in isolated membranes prepared from (/sup 32/P)labelled platelets. In the presence of guanosine 5'-(3-O)-thiotriphosphate (GTP..gamma..S), thrombin increased the release of inositol triphosphate and inositol biphosphate approximately 500%. GTP..gamma..S alone stimulated release 2 fold. Maximal activation of thrombin-induced phosphoinositide hydrolysis was observed at 10 ..mu..M GTP. Although addition of calcium had no effect, 2 mM EGTA completely inhibited inositolphosphate release. Addition of high speed supernatant to (/sup 32/P)labelled membranes stimulated the release of inositolphosphates. This hydrolysis was further enhanced by the addition of GTP. These data demonstrate that the breakdown of polyphosphoinositides in isolated platelet membranes is dependent on GTP and stimulated by platelet cytosol.

Baldassare, J.J.; Fisher, G.J.

1986-06-13

404

Homogeneous catalysis of valeronitrile hydrolysis under supercritical conditions.  

PubMed

Supercritical nitrile hydrolysis can be used for both, amide and acid production as well as waste water treatment, as the hydrolysis products show good biodegradability. The conventional process at ambient conditions requires large amounts of mineral acid or base. Approaches that use supercritical water as a green solvent without a catalyst have been investigated over recent years. Findings for valeronitrile hydrolysis presented recently showed promising reaction rates and valeric acid yields. In an attempt to further maximize product yield and to better understand the impact of the pH, reactions in dilute sulfuric acid (0.01 mol L(-1)) were performed in a continuous high-pressure laboratory-scale apparatus at 400-500 °C, 30 MPa, and a maximum residence time of 100 s. Results from both reaction media were compared with regard to productivity and sustainability. PMID:22190404

Sarlea, Michael; Kohl, Sabine; Blickhan, Nina; Vogel, Herbert

2011-12-20

405

Characteristics of enzyme hydrolysis of cellulose under static condition.  

PubMed

The effect of enzyme loading under static and agitated conditions was investigated. Enzymatic hydrolysis of 10 w/v% de-lignified cellulose slurry such as filter paper, avicel and pulp was conducted under agitated (120 rpm) and static condition, and the enzyme loading ranging from 1.2 to 120 mg-protein/g-dry substrate. Under the agitated condition, the final sugar concentration decreased with the decreasing enzyme loading. Under the static condition, the final sugar concentration was maintained even if the enzyme loading was decreased. The above phenomenon was caused by a rapid precipitation of cellobiohydrolase 2 (CBH2) under the agitated condition, which was not observed under the static condition. The hydrolysis experiments using enzymes containing different ratios of cellobiohydrolase 1 (CBH1) and CBH2 under the static condition suggested that preservation of CBH2 and its synergism with CBH1 is essential for static condition's characteristics, and for efficient hydrolysis of cellulose. PMID:22858480

Taneda, Daisuke; Ueno, Yoshiki; Ikeo, Makoto; Okino, Shohei

2012-07-07

406

Determining yields in high solids enzymatic hydrolysis of biomass.  

PubMed

As technologies for utilizing biomass for fuel and chemical production continue to improve, enzymatic hydrolysis can be run at still higher solids concentrations. For hydrolyses that initially contain little or no free water (10-40% total solids, w/w), the saccharification of insoluble polymers into soluble sugars involves changes of volume, density, and proportion of insoluble solids. This poses a new challenge when determining the degree of hydrolysis (conversion yield). Experiments have shown that calculating the yield from the resulting sugar concentration in the supernatant of the slurry and using the assumed initial volume leads to significant overestimations of the yield. By measuring the proportion of insoluble solids in the slurry as well as the sugar concentration and specific gravity of the aqueous phase, it is possible to precisely calculate the degree of conversion. The discrepancies between the different ways of calculating yields are demonstrated along with a nonlaborious method for approximating yields in high solids hydrolysis. PMID:18836690

Kristensen, Jan B; Felby, Claus; Jørgensen, Henning

2008-10-04

407

Base hydrolysis and hydrothermal processing of PBX-9404 explosive  

SciTech Connect

Base hydrolysis in combination with hydrothermal processing has been proposed as an environmentally acceptable alternative to open burning/open detonation for degradation and destruction of high explosives. In this report, we examine gaseous and aqueous products of base hydrolysis of the HMX-based plastic bonded explosive, PBX-9404. We also examine products from the subsequent hydrothermal treatment of the base hydrolysate. The gases produced from hydrolysis of PBX-9404 are ammonia, nitrous oxide, and nitrogen. Major aqueous products are sodium formate, acetate, nitrate, and nitrite, but not all carbon products have been identified. Hydrothermal processing of base hydrolysate destroyed up to 98% of the organic carbon in solution, and higher destruction efficiencies are possible. Major gas products detected from hydrothermal processing were nitrogen and nitrous oxide.

Sanchez, J.A.; Flesner, R.L.; Spontarelli, T.; Dell`Orco, P.C.; Kramer, J.F.

1994-12-31

408

Impact of ?-amylase combined with hydrochloric acid hydrolysis on structure and digestion of waxy rice starch.  

PubMed

The structure and in vitro digestibility of native waxy rice starch by the combined hydrolysis of ?-amylase and hydrochloric acid were investigated in this study. The combined hydrolysis technique generated higher hydrolysis rate and extent than the enzymatic hydrolysis. The granular appearance and chromatograph profile demonstrated that ?-amylase and hydrochloric acid exhibited different patterns of hydrolysis. The rise in the ratio of absorbance 1047/1022cm(-1), the melting temperature range (Tc-To), and the melting enthalpy (?H) were observed during the combined hydrolysis. These results suggest that ?-amylase simultaneously cleaves the amorphous and crystalline regions, whereas the amorphous regions of starch granules are preferentially hydrolyzed during the acid hydrolysis. Furthermore, the combined hydrolysis increased rapidly digestible starch (RDS) while decreased slowly digestible starch (SDS) and resistant starch (RS), indicating that the hydrolysis mode affected the digestion property of native waxy rice starch. PMID:23357798

Li, Hongyan; Zhu, Yanqiao; Jiao, Aiquan; Zhao, Jianwei; Chen, Xiaoming; Wei, Benxi; Hu, Xiuting; Wu, Chunsen; Jin, Zhengyu; Tian, Yaoqi

2013-01-26

409

Bacterial hydrolysis and methane fermentation of lignocellulosic materials  

SciTech Connect

In order for methane fermentation of lignocellulosic materials to be an effective method for providing both a renewable energy source and a means to reduce the volume of municipal solids wastes, a better understanding of the fermentation process is required, because this process has been generally observed to be a slow and incomplete one. This dissertation focused on understanding of the rate-limiting mechanisms of methane fermentation, including the influence of the type of lignocellulosic materials, bacterial culture characteristics, bacterial concentration, pH, and temperature. Lignocellulosic materials selected for this study were: corn stover, wheat straw, napier grass, wood grass, newspaper, and white fir. Four methanogenic cultures grown on monosaccharides, purified holocellulose, wheat straw, and mixed municipal sludge, respectively, were developed at 35[degrees]C and neutral pH. Each of the four bacterial cultures developed a glucose and cellobiose consumption potential higher than the methanogenic potential, which in turn was higher than the lignocellulosic hydrolysis potential. Further examination of lignocellulosic hydrolysis revealed that it is the step in which bacteria and enzymes can have access to holocellulosic polymers that limits the hydrolysis rate. Microscopic examination revealed that hydrolysis appears to have occurred only at the points of physical contact between the hydrolytic bacteria and the particle surface. Both fermentation rate and extent were greatly influenced by the lignocellulosic material used and by pH and temperature, but they were much less affected by the bacterial culture employed. Lignocellulosic hydrolysis reached a maximum rate at relatively low bacterial concentrations. Both hydrolysis and fermentation processes can be adequately modeled by a first-order rate equation. Linear correlations between lignin content and biodegradability or methane conversion rate were very poor.

Tong, X.

1992-01-01

410

Method of increasing the sulfation capacity of alkaline earth sorbents  

DOEpatents

A system and method for increasing the sulfation capacity of alkaline earth carbonates to scrub sulfur dioxide produced during the fluidized bed combustion of coal in which partially sulfated alkaline earth carbonates are hydrated in a fluidized bed to crack the sulfate coating and convert the alkaline earth oxide to the hydroxide. Subsequent dehydration of the sulfate-hydroxide to a sulfate-oxide particle produces particles having larger pore size, increased porosity, decreased grain size and additional sulfation capacity. A continuous process is disclosed.

Shearer, John A. (Chicago, IL); Turner, Clarence B. (Shorewood, IL); Johnson, Irving (Clarendon Hills, IL)

1982-01-01

411

Process for preparing zinc powder for alkaline batteries  

SciTech Connect

A zinc powder having a low gas evolution in an alkaline electrolyte for use in an alkaline battery are obtained by alloying the zinc with at least one metal selected from the group consisting of lead, cadmium, thallium and indium and at least one further metal selected from the group consisting of lead, cadmium, thallium, indium gold, silver, tin and gallium. Thereby it is possible to avoid the use of mercury as an alloying element but nevertheless to obtain a zinc powder which meet all of the requirements for use in alkaline batteries.

Glaeser, W.

1985-10-22

412

Method of increasing the sulfation capacity of alkaline earth sorbents  

DOEpatents

A system and method for increasing the sulfation capacity of alkaline earth carbonates to scrub sulfur dioxide produced during the fluidized bed combustion of coal in which partially sulfated alkaline earth carbonates are hydrated in a fluidized bed to crack the sulfate coating and convert the alkaline earth oxide to the hydroxide. Subsequent dehydration of the sulfate-hydroxide to a sulfate-oxide particle produces particles having larger pore size, increased porosity, decreased grain size and additional sulfation capacity. A continuous process is disclosed.

Shearer, J.A.; Turner, C.B.; Johnson, I.

1980-03-13

413

Hydrolysis of sugarcane bagasse by mycelial biomass of Penicillium funiculosum  

SciTech Connect

Cellulose bioconversion has great promise for producing unlimited quantities of fermentable feedstocks and liquid fuels. Extensive studies on the production of extracellular cellulase and on the saccharification of various cellulosic substrates using cellulases have been reported. Use of mycelial biomass having cell bound cellulase for saccharification of cellulose was studied in Aspergillus terreus by Miller and Srinivasan. Extracellular cellulase production by P. funiculosum and its application for cellulose hydrolysis have been reported earlier by the authors. The present communication reports the hydrolysis of lignocellulose using mycelial biomass of P. funiculosum cultivated on cellulose and its reuse potential. 10 references.

Rao, M.; Deshpande, V.; Seeta, R.; Srinivasan, M.C.; Mishra, C.

1985-07-01

414

Hydrolysis of an organophosphate ester by manganese dioxide.  

PubMed

Amorphous manganese dioxide facilitates the hydrolysis of p-nitrophenyl phosphate to p-nitrophenol and orthophosphate despite insignificant adsorption of p-nitrophenyl phosphate or p-nitrophenol to the manganese dioxide. At pH 8, the orthophosphate product is released into solution; at pH 4 and pH 6, some remains adsorbed. The rate of hydrolysis is an order of magnitude more rapid than the same reaction facilitated by iron oxides. Because manganese dioxides are ubiquitous components of soils and sediments, this suggests the possibility of significant abiotic pathways for the formation of bioavailable orthophosphate from phosphate ester precursors. PMID:11349282

Baldwin, D S; Beattie, J K; Coleman, L M; Jones, D R

2001-02-15

415

Recovery by ultrafiltration of a commercial enzyme for cellulose hydrolysis  

SciTech Connect

An enzymatic process of cellulose hydrolysis based mainly on the use of membrane techniques is under study. The proposed flow sheet assumes that during cellulose hydrolysis the enzyme is continuously separated from glucose and cellobiose and is recycled in the cellulose reaction vessel by membrane ultrafiltration. The ultrafiltration of Celluclast enzyme by Novo is performed in a DDS column module assembled with flat polysulfone membranes. Membrane polarization effects are studies in the 0.1-5% w/v enzyme concentration range under varying pressures up to 600 kPa. A partial loss of enzymatic activity is observed as a consequence of the ultrafiltration and membrane washing operations.

Pizzichini, M.; Fabiani, C.; Sperandei, M. (ENEA, Rome (Italy))

1991-02-01

416

Snapshots of the maltose transporter during ATP hydrolysis  

PubMed Central

ATP-binding cassette transporters are powered by ATP, but the mechanism by which these transporters hydrolyze ATP is unclear. In this study, four crystal structures of the full-length wild-type maltose transporter, stabilized by adenosine 5?-(?,?-imido)triphosphate or ADP in conjunction with phosphate analogs , , or , were determined to 2.2- to 2.4-? resolution. These structures led to the assignment of two enzymatic states during ATP hydrolysis and demonstrate specific functional roles of highly conserved residues in the nucleotide-binding domain, suggesting that ATP-binding cassette transporters catalyze ATP hydrolysis via a general base mechanism.

Oldham, Michael L.; Chen, Jue

2011-01-01

417

Accelerating enzymatic hydrolysis of chitin by microwave pretreatment.  

PubMed

Response surface analysis was used to determine optimum conditions [2% (w/v) chitin, 57.5 degrees C, 38 min] for microwave irradiation of chitin to improve its enzymatic hydrolysis. V(max)/K(m) of cabbage chitinase toward untreated and microwave-irradiated chitin was found to be 21.1 and 31.7 nmol h(-1) mg(-2) mL, respectively. Similar improvement was observed in the case of pectinase in its unusual catalytic activity of chitin degradation. It was found that a greater extent of chitin hydrolysis by chitinase was possible after the substrate chitin was irradiated with microwaves. PMID:14656136

Roy, Ipsita; Mondal, Kalyani; Gupta, Munishwar N

418

Henry's law constant and hydrolysis of peroxyacetyl nitrate (PAN)  

Microsoft Academic Search

The effect of temperature on the solubility of PAN and on its hydrolysis rate in near-neutral and slightly acidic water were studied in a bubble column apparatus. The results obtained are a Henry's law coefficient H=10-9.04±0.6 exp[(6513±376)\\/T] M atm-1, and a first-order hydrolysis rate constant k=106.60±1.0 exp[(-6612±662)\\/T] s-1, which was independent of pH in the range 3.2=pH=6.7. The products formed

Jost Kames; Silke Schweighoefer; Ulrich Schurath

1991-01-01

419

The Martian ocean: First acid, then alkaline  

NASA Astrophysics Data System (ADS)

In Mars' distant past, carbon dioxide and water may have been plentiful. Values of total outgassed CO2 from several to about 10 bar are consistent with present knowledge, and this amount of CO2 implies an amount of water outgassed equal to an equivalent depth of 500 to 1000 m. It is quite reasonable, therefore, to envision an early Mars in which there was a body or bodies of liquid water, perhaps in the northern plains, and a dense carbon dioxide atmosphere. Under such conditions, the pH of the water will be low, due to the dissolution of carbon dioxide in the water to form carbonic acid. This acidic water is capable of weathering the available rock quite intensely, particularly because this rock is likely to be heavily fractured (from meteorite bombardment) or even consist of fine particles (such as pyroclastic deposits). As time goes on, however, the carbon dioxide atmosphere will rapidly pass through the ocean to form carbonate deposits. As the density of the atmosphere decreases, so will the flux of carbonic acid into the ocean. Without this input of carbonic acid, the effect of the dissolved weathering products will be to increase the pH of the water. The ocean will then become alkaline. To study this process, I have developed a geochemical cycle model for the atmosphere-hydrosphere-regolith system of Mars. The treatment of geochemical cycles as complex kinetic chemical reactions has been undertaken for terrestrial systems in recent years with much success. This method is capable of elegantly handling the interactions between the simultaneous chemical reactions needed to understand such a system.

Schaefer, M. W.

1993-09-01

420

Degradation pathways of ampicillin in alkaline solutions.  

PubMed

Ampicillin trihydrate, sodium salt, in aqueous solution has a pH of about 8. No complete degradation pathway has been proposed to explain the degradation of ampicillin under alkaline conditions and the information available explains the formation of only certain products. The present work was carried out with the aim of providing this information. The formation of degradation products of ampicillin trihydrate, sodium salt, produced in aqueous solutions (pH 12 and 37 degrees C) have been studied as an accelerated form of the possible degradation that may occur in aqueous solutions at pH 8. Some of the degradation products formed under these conditions were then obtained either by synthesis or by degradation of ampicillin sodium followed by isolation using semi-preparative HPLC. These compounds were characterized by 1H NMR spectroscopy. The information obtained from the experiments by HPLC and NMR spectroscopy made it possible to propose a degradation pathway for ampicillin under the conditions described above. 5R-penicilloic acid is the first degradation product of ampicillin and subsequently undergoes epimerization at C-5 to form the 5S isomer via the imine tautomer. Mechanisms for the formation of compounds previously believed to form only under acidic conditions are proposed, i.e. ampicillin penilloic acid and 2-hydroxy-3-phenylpyrazine. The formation of ampicillin polymers was detected in dilute solutions (1% w/v) within a few hours of dissolution. The presence of ampicillin penicillenic acid and ampicillin penamaldic acid was detected by 1H NMR and their main spectroscopic features determined. PMID:9306250

Robinson-Fuentes, V A; Jefferies, T M; Branch, S K

1997-09-01

421

Nordic Seas total alkalinity data in CARINA  

NASA Astrophysics Data System (ADS)

Water column data of inorganic carbon and carbon relevant hydrographic and hydrochemical parameters from 188 previously non-publicly available cruises in the Arctic, Atlantic, and Southern Ocean have been retrieved and merged into a new database: CARINA (CARbon IN the Atlantic). The data have been subject to rigorous quality control (QC) in order to ensure highest possible quality and consistency. The data for most of the parameters included were examined in order to quantify systematic biases in the reported values, i.e. secondary quality control. The quality control was carried out separately in each of the three CARINA regions: The Arctic Mediterranean Seas (AMS), the Atlantic (ATL), and the Southern Ocean (SO). The AMS was further split up into the Arctic Ocean and Nordic Seas during the secondary QC. The quality control of the different parameters in the different regions is described in the series of papers in this special issue of ESSD, with this contribution focusing on the Nordic Seas total alkalinity (ALK) data. Significant biases have been corrected for in the data products, i.e. the three merged files with measured, calculated and interpolated values for each of the three CARINA regions (AMS, SO and ATL). With the adjustments the CARINA database is consistent both internally as well as with GLODAP (Key et al., 2004) and is suitable for accurate assessments of, for example, oceanic carbon inventories and uptake rates and for model validation. Out of the 35 cruises from the Nordic Seas included in CARINA, 21 had ALK data. The data from 6 of these were found to be of low quality and should not be used. Of the others, 3 were found to be biased low and were subject to adjustment. Thus the final CARINA data product contains ALK data from 15 cruises from the Nordic Seas, and these data appear consistent to ±3 ?mol kg-1.

Olsen, A.

2009-12-01

422

Nordic Seas total alkalinity data in CARINA  

NASA Astrophysics Data System (ADS)

Water column data of carbon and carbon relevant hydrographic and hydrochemical parameters from 188 previously non-publicly available cruises in the Arctic, Atlantic, and Southern Ocean have been retrieved and merged into a new database: CARINA (CARbon IN the Atlantic). The data have been subject to rigorous quality control (QC) in order to ensure highest possible quality and consistency. The data for most of the parameters included were examined in order to quantify systematic biases in the reported values, i.e. secondary quality control. Significant biases have been corrected for in the data products, i.e. the three merged files with measured, calculated and interpolated values for each of the three CARINA regions; the Arctic Mediterranean Seas (AMS), the Atlantic (ATL) and the Southern Ocean (SO). With the adjustments the CARINA database is consistent both internally as well as with GLODAP (Key et al., 2004) and is suitable for accurate assessments of, for example, oceanic carbon inventories and uptake rates and for model validation. The Arctic Mediterranean Seas includes the Arctic Ocean and the Nordic Seas, and the quality control was carried out separately in these two areas. This contribution presents an account of the quality control of the total alkalinity (ALK) data from the Nordic Seas in CARINA. Out of the 35 cruises from the Nordic Seas included in CARINA, 21 had ALK data. The data from 6 of these were found to be of low quality and should not be used. Of the others, 3 were found to be biased low and were subject to adjustment. Thus the final CARINA data product contains ALK data from 15 cruises from the Nordic Seas, and these data appear consistent to ±3 ?mol kg-1.

Olsen, A.

2009-08-01

423

Research on Separators for Alkaline Zinc Batteries. Final Report.  

National Technical Information Service (NTIS)

This project is concerned with the research and development of a hybrid separator as an improved battery separator in alkaline zinc secondary batteries. Particular emphasis has been directed toward increasing the cycle life of zinc electrodes by controlli...

R. S. Yeo

1985-01-01

424

Research on Separators for Alkaline Zinc Batteries. Final Report.  

National Technical Information Service (NTIS)

This project is concerned with the research and development of a hybrid separator as an improved battery separator in alkaline zinc secondary batteries. Particular emphasis has been directed toward mitigating the failure of zinc electrodes by controlling ...

R. S. Yeo

1984-01-01

425

Processes affecting the oceanic distributions of dissolved calcium and alkalinity  

SciTech Connect

Recent studies of the CO/sub 2/ system have suggested that chemical processes in addition to the dissolution and precipitation of calcium carbonate affect the oceanic calcium and alkalinity distributions. Calcium and alkalinity data from the North Pacific have been examined both by using the simple physical-chemical model of previous workers and by a study involving the broader oceanographic context of these data. The simple model is shown to be an inadequate basis for these studies. Although a proton flux associated with organic decomposition may affect the alkalinity, previously reported deviations of calcium-alkalinity correlations from expected trends appear to be related to boundary processes that have been neglected rather than to this proton flux. The distribution of calcium in the surface waters of the Pacific Ocean is examined.

Shiller, A.M.; Gieskes, J.M.

1980-05-20

426

21 CFR 864.7660 - Leukocyte alkaline phosphatase test.  

Code of Federal Regulations, 2013 CFR

...ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES HEMATOLOGY AND PATHOLOGY DEVICES Hematology Kits and Packages § 864.7660 Leukocyte alkaline phosphatase test. (a) Identification. A leukocyte...

2013-04-01

427

Kinetics of the Fading of Phenolphthalein in Alkaline Solution.  

ERIC Educational Resources Information Center

Described is an experiment which illustrates pseudo-first-order kinetics in the fading of a common indicator in an alkaline solution. Included are background information, details of materials used, laboratory procedures, and sample results. (CW)

Nicholson, Lois

1989-01-01

428

Mechanical Properties of Alkaline-Earth Doped Lanthanum Gallate  

SciTech Connect

Report on mechanical properties of Lanthanum Gallate. Lanthanum gallate doped with alkaline earths was prepared from combustion-synthesized powders. Mechanical properties of the doped gallates were evaluated as a function of composition and temperature.

Baskaran, Suresh; Lewinsohn, Charles A.; Chou, Y S.; Qian, Maoxu; Stevenson, Jeffry W.; Armstrong, Timothy R.

1999-08-01

429

Method of Improving the Storage Properties of Alkaline Detergent Compositions.  

National Technical Information Service (NTIS)

The non-caking storage stable alkaline detergent composition contains 52.5 percent sodium tripolyphosphate (by weight), 35 percent sodium metasilicate pentahydrate, and 10.5 percent sodium primary phosphate monohydrate coated with 2 percent octyl pheyl po...

A. Mankowich

1964-01-01

430

Applying WEPP technologies to western alkaline surface coal mines  

Treesearch

Rocky Mountain Research Station ... Title: Applying WEPP technologies to western alkaline surface coal mines ... Description: One aspect of planning surface mining operations, regulated by the National Pollutant Discharge Elimination ...

431

The purification and activities of an alkaline protease of Aspergillus clavatus from Nigerian poultry feeds.  

PubMed

Optimal growth and extracellular protease production by Aspergillus clavatus Des. was recorded at 30 degrees C and between days 5 and 7 of the 8-day incubation period. Purification of this enzyme was achieved by a combination of ultrafiltration, alcoholic precipitation and fractionation on DEAE-cellulose and Sephadex-G.200. A single peak of an alkaline protease was subsequently obtained with a 9-fold increase in specific activity and a final recovery value of 26.2%. The enzyme had optimal activity at 37 degrees C and a pH of 7.8. The enzyme did not degrade leucine amide, hippurylphenylalanine and hippurylarginine indicating lack of exo-protease activity. However, endo-protease activity led to a rapid hydrolysis of gelatin with optimal activity at 40 degrees C and pH 7.8. The high incidence of A. clavatus on Nigerian poultry feeds vis-a-vis the potential health risks posed to farm animals is discussed. PMID:3534215

Ogundero, V W; Osunlaja, S O

1986-01-01

432

Improved oil recovery using alkaline solutions in limestone medium  

Microsoft Academic Search

In this study, the effect of sodium hydroxide (NaOH) and sodium silicate (NaSiO4) solutions for the improved oil recovery of Garzan (26 API°) and Raman (17.2 API°) crude oils with variable salinity of the alkaline solutions, and the effect of injection flow rate at the salinity values of the alkaline solutions that yielded maximum oil recovery for both crude oils

Ula? Türksoy; Suat Ba?ci

2000-01-01

433

Endurance test and evaluation of alkaline water electrolysis cells  

Microsoft Academic Search

Utilization in the development of multi-kW low orbit power systems is discussed. The following technological developments of alkaline water electrolysis cells for space power application were demonstrated: (1) four 92.9 cm2 single water electrolysis cells, two using LST's advanced anodes and two using LST's super anodes; (2) four single cell endurance test stands for life testing of alkaline water electrolyte

K. A. Burke; F. H. Schubert

1981-01-01

434

[Transient alkaline hyperphosphatemia of childhood. Description of a clinical case].  

PubMed

Transient idiopathic alkaline hyperphosphatasemia is a syndrome of unknown etiology unrelated to any specific disease, characterized by a marked transient increase of the serum level of alkaline phosphatase. About fifty-two cases of them included from thirty-seven to two months have been reported in Literature till now. A new case of a little girl four years and three months old is reported here. PMID:3328161

Dello Iacono, I; Tomaselli, D E; Quarantiello, F; Vicario, V; Sellitto, F

435

Crystallization of alkaline protease as a means of purification process  

Microsoft Academic Search

A purification protocol of alkaline protease purification using crystallization was developed by investigating the effects\\u000a of pH, temperature, initial enzyme concentration, salt (as crystal inducer) concentration, and the presence of impurity proteins.\\u000a A commercial alkaline protease solution was used as a starting material and NaCl was used as a crystal inducing salt. The\\u000a crude enzyme solution was first diafiltered against

Dong Ha Park; Ho Joon Lee; Eun Kyu Leer

1997-01-01

436

Sulfur storage and alkalinity generation in New England lake sediments  

Microsoft Academic Search

We measured rates of burial and forms of reduced S in lake sediments to evaluate the importance of SO,z- reduction to the alkalinity budget of several New England lakes. The contribution of dissimilatory SOd2- reduction to alkalinity generation in these lakes was estimated conservatively to range from 1 to 75 meq m-2 yr-l. The contribution of both assimilatory and dissimilatory

ANNE E. GIBLIN; GENE E. LIKENS; DAVID WHITE; ROBERT W. HOWARTH

1990-01-01

437

Solvent Extraction of Tc and Cs from Alkaline Nitrate Wastes  

SciTech Connect

This paper summarizes progress at three collaborating U.S. national laboratories on the extraction of the fission products 99Tc and 137Cs from alkaline high-level wastes. Efficient economical processes for Tc and Cs extraction (SRTALK and alkaline-side CSEX, respectively) have been developed, and testing has progressed through batch tests on actual wastes and continuous counter-current centrifugal-contactor tests on simulants.

Moyer, Bruce A. (OAK RIDGE NATIONAL LAB); Bonnesen, Peter V. (ORNL); Delmau, Laetitia H. (OAK RIDGE NATIONAL LAB); Haverlock, T J. (Oak Ridge National Laboratory); Sachleben, R A. (Oak Ridge National Laboratory); Leonard, R A. (Argonne National Laboratory); Conner, C (Argonne National Laboratory); Lumetta, Gregg J. (BATTELLE (PACIFIC NW LAB)); M. Cox, M. Hidalgo, and M. Valiente

2001-01-01

438

FURNACE INJECTION OF ALKALINE SORBENTS FOR SULFURIC ACID CONTROL  

Microsoft Academic Search

This document summarizes progress on Cooperative Agreement DE-FC26-99FT40718, Furnace Injection of Alkaline Sorbents for Sulfuric Acid Control, during the time period October 1, 2001 through March 31, 2002. The objective of this project is to demonstrate the use of alkaline reagents injected into the furnace of coal-fired boilers as a means of controlling sulfuric acid emissions. The coincident removal of

Gary M. Blythe

2002-01-01

439

FURNACE INJECTION OF ALKALINE SORBENTS FOR SULFURIC ACID CONTROL  

Microsoft Academic Search

This document summarizes progress on Cooperative Agreement DE-FC26-99FT40718, Furnace Injection of Alkaline Sorbents for Sulfuric Acid Control, during the time period October 1, 2002 through March 31, 2003. The objective of this project is to demonstrate the use of alkaline reagents injected into the furnace of coal-fired boilers as a means of controlling sulfuric acid emissions. The coincident removal of

Gary M. Blythe

2003-01-01

440

FURNACE INJECTION OF ALKALINE SORBENTS FOR SULFURIC ACID CONTROL  

Microsoft Academic Search

This document summarizes progress on Cooperative Agreement DE-FC26-99FT40718, Furnace Injection of Alkaline Sorbents for Sulfuric Acid Control, during the time period April 1, 2001 through September 30, 2001. The objective of this project is to demonstrate the use of alkaline reagents injected into the furnace of coal-fired boilers as a means of controlling sulfuric acid emissions. The coincident removal of

Gary M. Blythe

2001-01-01

441

FURNACE INJECTION OF ALKALINE SORBENTS FOR SULFURIC ACID CONTROL  

Microsoft Academic Search

This document summarizes progress on Cooperative Agreement DE-FC26-99FT40718, Furnace Injection of Alkaline Sorbents for Sulfuric Acid Control, during the time period April 1, 2003 through September, 2003. The objective of this project is to demonstrate the use of alkaline reagents injected into the furnace of coal-fired boilers as a means of controlling sulfuric acid emissions. The coincident removal of hydrochloric

Gary M. Blythe

2003-01-01

442

Neutralization of alkaline industrial wastewaters using Exiguobacterium sp  

Microsoft Academic Search

A facultatively alkaliphilic bacterium capable of lowering the pH of highly alkaline wastewater from 12.0 to 7.5 within just 2.0 h was isolated from industrial wastewater drained sludge of a local beverage industry. The metabolic product which the bacterium produces in order to neutralize alkaline wastewater was found to be carboxylic acid in nature by Fourier Transform- Infrared (FT-IR) spectroscopy. The isolate

Niha Mohan Kulshreshtha; Anil Kumar; Purnima Dhall; Saurabh Gupta; Gopal Bisht; Santosh Pasha; V. P. Singh; Rita Kumar

2010-01-01

443

Adsorptive Performances of Alkaline Treated Peat for Heavy Metal Removal  

Microsoft Academic Search

The adsorptive performances of alkaline treated peat have been investigated for the removal of Pb(II), Co(II), and Ni(II) ions from aqueous solutions. The influence of initial metal ions concentration and equilibrium contact time was studied in a series of batch experiments, in comparison with natural peat. An increasing of adsorption capacity of alkaline treated peat was obtained for all studied

Laura Bulgariu; Dumitru Bulgariu; Matei Macoveanu

2011-01-01

444

The Preparation and Enzymatic Hydrolysis of a Library of Esters  

ERIC Educational Resources Information Center

|An investigative case study involving the preparation of a library of esters using Fischer esterification and alcoholysis of acid chlorides and their subsequent enzymatic hydrolysis by pig liver esterase and orange peel esterase is described. Students work collaboratively to prepare and characterize the library of esters and complete and evaluate…

Sanford, Elizabeth M.; Smith, Traci L.

2008-01-01

445

Evaluation of Cation Hydrolysis Schemes with a Pocket Calculator.  

ERIC Educational Resources Information Center

Described is the use of two models of pocket calculators. The Hewlett-Packard HP67 and the Texas Instruments TI59, to solve problems arising in connection with ionic equilibria in solution. A three-parameter regression program is described and listed as a specific example, the hydrolysis of hexavalent uranium, is provided. (BT)

Clare, Brian W.

1979-01-01

446

Concentrated Acid Impregnation, Hydrolysis, and Fermentation of Reed to Ethanol  

Microsoft Academic Search

The technical feasibility of bioethanol production from reed, energy crop was evaluated by way of a simple acid treatment at a low temperature. The main goal of this study was to investigate the effect of various acid-to-biomass ratios, impregnation durations, and hydrolysis periods on conversion yield of reed to monomeric sugars and inhibitors production. As a result, the maximum glucan

Hee Cheon Moon; I. S. Song; D. H. Kim

2010-01-01

447

Effect of Supporting Electrolyte on Hydrolysis of Sunflower Protopectin  

Microsoft Academic Search

The effect of supporting electrolyte on the kinetics of hydrolysis of protopectin (PP) from sunflower heads is studied. The yield of principal decomposition products is determined. The kinetic parameters of the reaction are calculated. Increasing the concentration of supporting electrolyte by adding NaCl to the reaction mixture increases the rate of PP decomposition by 2.5 times and the yield of

D. Kh. Khalikov; Kh. Kh. Avloev; R. M. Gorshkova; Z. K. Mukhiddinov; Kh. Teshaev

2002-01-01

448

Effect of particle size on enzymatic hydrolysis of pretreated Miscanthus  

Technology Transfer Automated Retrieval System (TEKTRAN)

Particle size reduction is a crucial factor in transportation logistics as well as cellulosic conversion. The effect of particle size on enzymatic hydrolysis of pretreated Miscanthus x giganteus was determined. Miscanthus was ground using a hammer mill equipped with screens having 0.08, 2.0 or 6.0...

449

Hydrolysis column for an ammonium diuranate conversion line processing system  

Microsoft Academic Search

A hydrolysis column, used to hydrolyze uranium hexafluoride gas with water in an ammonium diuranate conversion process, which includes a pipe having a water inlet, a connector inserted in the pipe intermediate its length, and a gas nozzle connected to the connector to feed uranium hexafluoride gas into the water. Since the uranium hexafluoride gas will freeze at 147°F, the

Fuller

1978-01-01

450

Ethanol production with dilute acid hydrolysis using partially dried lignocellulosics  

DOEpatents

A process of converting lignocellulosic biomass to ethanol, comprising hydrolyzing lignocellulosic materials by subjecting dried lignocellulosic material in a reactor to a catalyst comprised of a dilute solution of a strong acid and a metal salt to lower the activation energy (i.e., the temperature) of cellulose hydrolysis and ultimately obtain higher sugar yields.

Nguyen, Quang A. (Chesterfield, MO); Keller, Fred A. (Lakewood, CO); Tucker, Melvin P. (Lakewood, CO)

2003-12-09

451

DFT STUDY OF THE HYDROLYSIS OF SOME S-TRIAZINES  

EPA Science Inventory

The acid-catalyzed hydrolysis of atrazine and related 2-chloro-s-triazines to the corresponding 2-hydroxy-s-triazines was investigated using the B3LYP hybrid density functional theory method. Gas-phase calculations were performed at the B3LYP/6-311++G(d,p)//B3LYP/6-31G* level of ...

452

Selective racemisation of esters: Relevance to enzymatic hydrolysis reactions  

Microsoft Academic Search

The selective racemisation of an ester in the presence of the corresponding acid has been demonstrated. Phenyl esters are significantly more prone to racemisation than methyl esters. Preliminary results indicate the utility of these results in enzyme-catalysed hydrolysis reactions.

William Harris; J WILLIAMS

1999-01-01

453

Penicillin Hydrolysis: A Kinetic Study of a Multistep, Multiproduct Reaction.  

ERIC Educational Resources Information Center

|Background, procedures used, and typical results are provided for an experiment in which students carry out the necessary measurements on the acid-catalysis of penicillin in two hours. By applying kinetic theory to the data obtained, the reaction pathways for the hydrolysis of potassium benzyl penicillin are elucidated. (JN)|

McCarrick, Thomas A.; McLafferty, Fred W.

1984-01-01

454

Acid Hydrolysis Lignin as a Sorbent for Naphthalene  

Microsoft Academic Search

Lignin, a major polymeric constituent of woody plant tissue, is an abundant source of natural organic matter available as a waste product from the pulp and paper and the fuel ethanol industries. In this study, the sorptive capacity of acid hydrolysis lignin for naphthalene, a representative nonpolar hydrophobic organic compound (HOC), was investigated. When powdered lignin is mixed with distilled

ANGELA KEANE; SUBHASIS GHOSHAL

2001-01-01

455

Structural modifications of lignocellulosics by pretreatments to enhance enzymatic hydrolysis  

Microsoft Academic Search

In this work an evaluation was made of a wide variety of single and multiple pretreatment methods for enhancing the rate of enzymatic hydrolysis of wheat straw. A multiple pretreatment consisted of a physical pretreatment followed by a chemical pretreatment. The structural features of wheat straw, including the specific surface area, crystallinity index, and lignin content, were measured to understand

M. M. Gharpuray; Yong-Hyun Lee; L. T. Fan

1983-01-01

456

Hydrolysis of lignocellulosic materials for ethanol production: a review  

Microsoft Academic Search

Lignocellulosic biomass can be utilized to produce ethanol, a promising alternative energy source for the limited crude oil. There are mainly two processes involved in the conversion: hydrolysis of cellulose in the lignocellulosic biomass to produce reducing sugars, and fermentation of the sugars to ethanol. The cost of ethanol production from lignocellulosic materials is relatively high based on current technologies,

Ye Sun; Jiayang Cheng

2002-01-01

457

Hydrolysis of pyridoxal isonicotinoyl hydrazone and its analogs  

Microsoft Academic Search

An orally available iron chelator is desirable for the treatment of secondary iron overload. Pyridoxal isonicotinoyl hydrazone (PIH) and its analogs effectively mobilize iron in vivo and in vitro, and are therefore promising candidates for this purpose. PIH analogs undergo significant amino acid-catalyzed hydrolysis in cell culture medium and in serum, achieving equilibrium with their corresponding aldehydes and hydrazides with

Joan L Buss; Prem Ponka

2003-01-01

458

Hydrolysis and phase transition of alpha-tricalcium phosphate  

Microsoft Academic Search

Increasing attention has been paid in recent years to alpha-tricalcium phosphate (?-TCP), which is used as the main constituent of calcium phosphate bioactive bone cements and biphasic calcium phosphate ceramics. Its hydrolysis and conversion into apatite phase may play an important role in new bone formation in vivo. In this experiment, ?-TCP powder was made and immersed in deionized water.

Li Yubao; Zhang Xingdong; K. de Groot

1997-01-01

459

Evaluation of Cation Hydrolysis Schemes with a Pocket Calculator.  

ERIC Educational Resources Information Center

|Described is the use of two models of pocket calculators. The Hewlett-Packard HP67 and the Texas Instruments TI59, to solve problems arising in connection with ionic equilibria in solution. A three-parameter regression program is described and listed as a specific example, the hydrolysis of hexavalent uranium, is provided. (BT)|

Clare, Brian W.

1979-01-01

460

17O NMR investigation of phosphite hydrolysis mechanisms.  

PubMed

The use of solution 17O NMR spectroscopy in verifying the mechanism of trialkyl phosphite hydrolysis is presented. Trimethyl phosphite was reacted with 17O-labeled H2O at different temperatures and two reactant concentrations, with the reaction being monitored by 17O NMR. Kinetic details elucidated from the NMR spectra are also discussed. PMID:18044801

McIntyre, Sarah K; Alam, Todd M

2007-12-01

461

Abnormal vascular phosphoinositide hydrolysis in the spontaneously hypertensive rat.  

PubMed Central

The production of [3H]-inositol phosphates was studied in labelled segments of aorta from spontaneously hypertensive rats (SHR) and Wistar Kyoto (WKY) controls at 5 and 19 weeks, either unstimulated or in the presence of noradrenaline. Basal hydrolysis of inositol phospholipids was significantly enhanced in young SHR (P less than 0.05) compared to controls but this difference was no longer detected at 19 weeks. Noradrenaline increased [3H]-inositol phosphate accumulation in both SHR and WKY, but maximal hydrolysis was significantly greater in WKY (P less than 0.01), although the ED50 was similar in both groups of animals. These data demonstrate that phosphatidylinositide hydrolysis is enhanced in the young hypertensive rat at the time blood pressure is rising, but that this activity has declined by the time hypertension has reached an established phase. In addition, alpha 1-agonist induction of inositol phospholipid hydrolysis differs in the two species of animals, being reduced in genetically mature hypertensive rats.

Heagerty, A. M.; Ollerenshaw, J. D.; Swales, J. D.

1986-01-01

462

Exploring potassium-dependent GTP hydrolysis in TEES family GTPases  

PubMed Central

GTPases are important regulatory proteins that hydrolyze GTP to GDP. A novel GTP-hydrolysis mechanism is employed by MnmE, YqeH and FeoB, where a potassium ion plays a role analogous to the Arginine finger of the Ras-RasGAP system, to accelerate otherwise slow GTP hydrolysis rates. In these proteins, two conserved asparagines and a ‘K-loop’ present in switch-I, were suggested as attributes of GTPases employing a K+-mediated mechanism. Based on their conservation, a similar mechanism was suggested for TEES family GTPases. Recently, in Dynamin, Fzo1 and RbgA, which also conserve these attributes, a similar mechanism was shown to be operative. Here, we probe K+-activated GTP hydrolysis in TEES (TrmE-Era-EngA-YihA-Septin) GTPases – Era, EngB and the two contiguous G-domains, GD1 and GD2 of YphC (EngA homologue) – and also in HflX, another GTPase that also conserves the same attributes. While GD1-YphC and Era exhibit a K+-mediated activation of GTP hydrolysis, surprisingly GD2-YphC, EngB and HflX do not. Therefore, the attrib