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Results 451 - 500 of 3191
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Harvey Ronald W - - 2010
The effects of a dilute (ionic strength=5x10(-3)M) plume of treated sewage, with elevated levels (3.9 mg/L) of dissolved organic carbon (DOC), upon the pH-dependency and magnitude of bacterial transport through an iron-laden, quartz sand aquifer (Cape Cod, MA) were evaluated using sets of replicate, static minicolumns. Compared with uncontaminated groundwater, ...
Shashi - - 2009
Acidity and alkalinity are independent parameters and they directly or indirectly regulate the pH of a medium. These are the prime factors which control the nature of the reactions in a medium. The present study was designed to explore the numerical interdependence of the three parameters and also, to develop ...
Stoodley Paul - - 2009
OBJECTIVE: To study the morphology and activity of tonsilloliths, demonstrating oxygen respiration, denitrification, and acidification on exposure to sucrose. STUDY DESIGN: Tonsilloliths were extracted in atraumatic conditions during tonsillectomy from 16 adults and sent to two different laboratories for histological, bacteriological, and biofilm studies under sterile conditions. SETTING: Multicenter laboratory ...
Kim Kang Min - - 2009
The identification and characterization of Bacillus polyfermenticus KJS-2 (B. polyfermenticus KJS-2) was conducted using TEM, an API 50CHB kit, 16S rDNA sequencing, a phylogenetic tree, and catalase and oxidase testing. The conversion rate of glucose to lactic acid by B. polyfermenticus KJS-2 was found to be 60.71+/-4.9%. In addition, treatment ...
Abdel-Latif Mohamed M M - - 2009
The molecular mechanisms by which gastric acid causes epithelial injury in the stomach and initiates an inflammatory reaction are poorly understood. We aimed in the present study to investigate the role of the early growth response gene Egr-1 and ERK in gastric epithelial cells following acid exposure, and the signaling ...
Heyder J - - 2009
Sixteen beagle dogs were housed in four large chambers under minimum restraint. They were exposed for 16 months to clean air and individual baseline data of markers were obtained. For 13 months, eight dogs were further exposed to clean air and eight dogs for 6 h/d to 1-microm MMAD (mass ...
Waddington L - - 2010
To investigate the effect of pH on the viability and the acid tolerance response (ATR) of bifidobacteria. The impact of low pH on the viability of five species of bifidobacteria was examined under conditions of strict anaerobiosis. Although differences in the ability to resist the lethal effects of low pH ...
Mackie A - - 2010
Cement kiln dust (CKD) is a fine-grained material produced during the manufacture of cement. Current reuse options are limited and the bulk of CKD not reused in the cement manufacturing process is sent to landfills or stored on-site. Due to the calcium oxide (CaO) content of CKD, it has the ...
Moslehi-Jenabian Saloomeh - - 2009
Survival and ability to respond to various environmental stresses such as low pH are important factors for lactobacilli for their function as probiotics. LuxS-mediated quorum sensing mechanism, which is based on the production of universal signal molecule called autoinducer-2 (AI-2), regulates important physiological traits and a variety of adaptive processes ...
Senadheera D - - 2009
The regulation of acid production in and the tolerance to low pH of the cariogenic bacterium Streptococcus mutans have garnered considerable attention since both of these properties contribute substantially to the virulence of this organism. Frequent or prolonged exposure to acid end products, mainly lactic acid, that are present following ...
Celli Jonathan P - - 2009
The ulcer-causing gastric pathogen Helicobacter pylori is the only bacterium known to colonize the harsh acidic environment of the human stomach. H. pylori survives in acidic conditions by producing urease, which catalyzes hydrolysis of urea to yield ammonia thus elevating the pH of its environment. However, the manner in which ...
Zhou Tong - - 2009
The tolerance of lactic acid bacteria (LAB) from kefir grains to gastrointestinal tract conditions was evaluated in vitro. The effects of pH values and bile salts on the viability of LAB were investigated. The results demonstrated that pH value showed a significant effect on the viability. The viable counts exhibited ...
Barboza-Silva E - - 2009
INTRODUCTION: The arginine deiminase system (ADS) of oral bacteria is a major generator of alkali (ammonia) in dental plaque and is considered to have anticaries effects. However, many of the antimicrobial agents used in oral care products may reduce alkali production by the ADS. The objective of our work was ...
Fu Dawei - - 2009
A new phytase (APPA) with optimum pH 2.5--substantially lower than that of most of microbial phytases (pH 4.5-6.0)--was cloned from Yersinia frederiksenii and heterologously expressed in Escherichia coli. Containing the highly conserved motifs typical of histidine acid phosphatases, APPA has the highest identity (84%) to the Yersinia intermedia phytase (optimal ...
Lee Pyung Cheon - - 2010
Succinic acid-producing Anaerobiospirillum succiniciproducens was anaerobically grown in a glycerol-fed continuous bioreactor in order to investigate the physiological responses of the cell to different pH values (5.9, 6.2, or 6.5) and various dilution rates, D. In these experiments, A. succiniciproducens showed a pH-dependent glycerol consumption behavior. When pH was maintained ...
Kottyan Leah C - - 2009
The microenvironment of the lung in asthma is acidic, yet the effect of acidity on inflammatory cells has not been well established. We now demonstrate that acidity inhibits eosinophil apoptosis and increases cellular viability in a dose-dependent manner between pH 7.5 and 6.0. Notably, acidity induced eosinophil cyclic adenosine 5'-monophosphate ...
Grigolon Ausilia - - 2009
OBJECTIVES: After meals, highly acidic gastric juice is present in the subcardial region, the so-called acid pocket. Patients with gastroesophageal reflux disease (GERD) have a higher frequency of acidic reflux. Our aim was to investigate the possible differences in subcardial pH in GERD over 24 h and the role of ...
Huang Yang - - 2010
The potential efficacy of four weak acids as preservatives in low-acid intermediate moisture foods was assessed using a glycerol based agar medium. The minimum inhibitory concentrations (MIC, % wt./wt.) of each acid was determined at two pH values (pH 5.0, pH 6.0) and two a(w) values (0.85, 0.90) for five ...
Li Jinjun - - 2009
With initial aging at low temperature for enough time, silicas with large mesoporosity were synthesized using triblock copolymer as template agent under weak acidities. SBA-15 with periodic mesostructure and short mesochannels could be synthesized at pH 2.5-3.0 within weak acidity range, and the surface areas, pore diameters and pore volumes ...
Sjöblom Markus - - 2009
Carbonic anhydrase (CA) is strongly expressed in the duodenum and has been implicated in a variety of physiological functions including enterocyte HCO(3)(-) supply for secretion and the "sensing" of luminal acid and CO(2). Here, we report the physiological role of the intracellular CAII isoform involvement in acid-, PGE(2,) and forskolin-induced ...
Droghetti Enrica - - 2009
The heme iron coordination of ferric myoglobin (Mb) in the presence of 9.0M urea and 8.0M acetic acid at acidic pH values has been probed by electronic absorption, magnetic circular dichroism and resonance Raman spectroscopic techniques. Unlike Mb at pH 2.0, where heme is not released from the protein despite ...
Gong Yongxing - - 2009
Streptococcus mutans in dental biofilms is regularly exposed to cycles of acidic pH during the ingestion of fermentable dietary carbohydrates. The ability of S. mutans to tolerate low pH is crucial for its virulence and pathogenesis in dental caries. To better understand its acid tolerance mechanisms, we performed genome-wide transcriptional ...
Kato Shiro - - 2009
Germination of Clostridium perfringens is known to be triggered by nutrients such as l-alanine and inosine, and facilitated by CO2, however the role of CO2 has not been fully understood. During the studies of the germination-specific protease GSP, we found that CO2 could be replaced by bicarbonate or weakly acidic ...
Persat Alexandre - - 2009
We review fundamental and applied acid-base equilibrium chemistry useful to microfluidic electrokinetics. We present elements of acid-base equilibrium reactions and derive rules for pH calculation for simple buffers. We also present a general formulation to calculate pH of more complex, arbitrary mixtures of electrolytes, and discuss the effects of ionic ...
Rieu A A Laboratoire de Recherche En Vigne et Vin REVV, Université de Bourgogne, IUVV, Dijon, - - 2010
To investigate how the survival of Listeria monocytogenes on parsley leaves may affect its ability to sustain process-related harsh conditions and its virulence. Parsley seedlings were spot inoculated with stationary phase cells of L. monocytogenes EGD-e and incubated for 15 days. Each day, bacterial cells were harvested and enumerated, and ...
Liu Li - - 2009
Although excitation-emission matrix spectroscopy (EEMS) has been widely used to characterize dissolved organic matter (DOM), there has no report that EEMS has been used to study the effects of acid rain on DOM and its composition in soil. In this work, we employed three-dimensional EEMS to characterize the compositions of ...
Zhu Heguang - - 2009
The requirements for pH buffer addition for hydrogen production and acidogenesis in batch acidogenic digestion of a food waste (FW) feedstock with limited alkalinity was studied at various initial pH conditions (6.0-8.0). The results showed that, without buffer addition, hydrogen production from this feedstock was insignificant regardless of the initial ...
Skandamis Panagiotis N - - 2009
This study aimed to evaluate the effects of the level and sequence of hurdles, applied during growth, on the subsequent heat and acid tolerances of a 10-strain composite of Listeria monocytogenes. Individual strains were grown in glucose-free tryptic soy broth with 0.6% yeast extract (TSBYE-G). Then cultures were mixed and ...
Simon K S - - 2009
Acidification is a widespread phenomenon that damages aquatic systems, and it has been the focus of intensive management efforts. While most management has focused on community structure as an endpoint, ecosystem function is also sensitive to acidification and important in stream health. We examined how a key ecosystem function in ...
Morel Jean-Pierre - - 2009
The enthalpy changes associated with the protonation and deprotonation of an alumina surface have been determined on the basis of microcalorimetry experiments and acid-base potentiometric titrations at 25 degrees C. It has been shown that the results may vary significantly according to the experimental procedure. In order to do so, ...
Tynkkynen Tuulia - - 2009
In this study, a protocol for pH determination from D(2)O samples using (1)H NMR pH indicator compounds was developed and assessed by exploring the pH-dependency of 13 compounds giving pH-dependent (1)H NMR signals. The indicators cover the pH range from pH(*) 0 to 7.2. Equations to transform the indicator chemical ...
Akar Tamer - - 2009
This study focuses on the possible use of macro-fungus Agaricus bisporus to remove Acid Red 44 dye from aqueous solutions. Batch equilibrium studies were carried out as a function of pH, biomass amount, contact time and temperature to determine the decolorization efficiency of biosorbent. The highest dye removal yield was ...
Alonso-Hernando Alicia - - 2009
Data on the ability of chemical poultry decontaminants to induce an acid stress response in pathogenic bacteria are lacking. This study was undertaken in order to compare the survival rates in acid broths of Listeria monocytogenes and Salmonella enterica strains, both exposed to and not exposed to decontaminants. The contribution ...
Zhang Peng - - 2009
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 ...
House B - - 2009
Enterohaemorrhagic Escherichia coli (EHEC) O157 : H7 is naturally exposed to a wide variety of stresses including gastric acid shock, and yet little is known about how this stress influences virulence. This study investigated the impact of acid stress on several critical virulence properties including survival, host adhesion, Shiga toxin ...
Karmakar Rajib - - 2009
The degradation of thiamethoxam [(EZ)-3-(2-chloro-1,3-thiazol-5-yl-methyl)-5-methyl-1,3,5-oxadiazinan-4-ylidene (nitro) amine] insecticide in buffers at different pH and temperature levels was investigated in laboratory studies. Acidic hydrolysis under conventional heating conditions and alkaline hydrolysis under both conventional heating and microwave conditions were carried out. Different hydrolysis products were found to form under alkaline and ...
Yang Hua - - 2009
Solutions of selected household products were tested for their effectiveness against Listeria monocytogenes, Escherichia coli O157:H7, and Salmonella Typhimurium. Hydrogen peroxide (1.5 and 3%), vinegar (2.5 and 5% acetic acid), baking soda (11, 33, and 50% sodium bicarbonate), household bleach (0.0314, 0.0933, and 0.670% sodium hypochlorite), 5% acetic acid (prepared ...
Steffan Joshua J - - 2009
Acidic extracellular pH (pHe) is a common feature of the tumor microenvironment and has been implicated in tumor invasion through the induction of protease secretion.Since lysosomes constitute the major storehouse of cellular proteases, the trafficking of lysosomes to the cell periphery may be required in order to secrete proteases. We ...
Devaraj K B - - 2009
Effect of pH on the conformational behaviour of ficin (EC 3.4.22.3), a cysteine protease from the latex of Ficus carica was monitored by circular dichroism, fluorescence spectroscopy, ANS binding and hydrodynamic studies. The results obtained from near- and far-UV CD, intrinsic fluorescence and ANS binding studies demonstrate that ficin exhibits ...
Hauck Markus - - 2009
The depsidone fumarprotocetraric acid as well as the depsides perlatolic and thamnolic acids are lichen secondary metabolites. Their first dissociation constants (pK(a1)) in methanol were determined to be 2.7 for perlatolic acid and 2.8 for fumarprotocetraric and thamnolic acids by UV spectroscopy. Lower pK(a1) values are, so far, not known ...
Mizumori Misa - - 2009
Regulation of localized extracellular pH (pH(o)) maintains normal organ function. An alkaline microclimate overlying the duodenal enterocyte brush border protects the mucosa from luminal acid. We hypothesized that intestinal alkaline phosphatase (IAP) regulates pH(o) due to pH-sensitive ATP hydrolysis as part of an ecto-purinergic pH regulatory system, comprised of cell-surface ...
Hu Yangbo - - 2009
Yersinia pseudotuberculosis is an enteric bacterium which must overcome the acidic stress in host organs for successful colonization, but how this bacterium survives in acidic conditions remains largely unknown. In the present study, the importance of OmpR in acid survival of Y. pseudotuberculosis YpIII was confirmed by the fact that ...
Jang Hye In - - 2009
The combined effects of caprylic acid and mild heat were investigated to ascertain their impact on Cronobacter spp. (E. sakazakii) in reconstituted infant formula. Samples containing a mixture of 3 strains of Cronobacter spp. (10(7) to 10(8) CFU/ml) were prepared with various concentrations of caprylic acid (5, 10, 20, and ...
Andréll Juni J Division of Molecular Biosciences, Imperial College, London SW7 2AZ, - - 2009
The acid-induced arginine decarboxylase is part of an enzymatic system in Escherichia coli that contributes to making this organism acid resistant. The arginine decarboxylase is a vitamin B(6)-dependent enzyme that is active at acidic pH. It consumes a proton in the decarboxylation of arginine to agmatine, and by working in ...
Miller Fátima A - - 2009
Acidification of foods with organic acids, either by fermentation or by intentional addition, is an important and common mechanism for controlling foodborne pathogens in a diversity of food products. The objective of this work was to study thermal inactivation of Listeria innocua, an acid tolerant microorganism, at 52.5, 60.0 and ...
Yoon Yohan - - 2009
Non-intact beef products include beef cuts that have been ground, mechanically tenderized, restructured, or have been injected with solutions to enhance tenderness and/or flavor. This study examined the effects of tenderizing salts and organic acids on thermal inactivation of Escherichia coli O157:H7 in a ground beef model system simulating non-intact ...
Joerger Rolf D - - 2009
For unknown reasons, Salmonella enterica Kentucky has become the serovar most frequently isolated from chickens and chicken carcasses in the United States. In an attempt to identify traits that may underlie this phenomenon, genetic and physiological features of 30 serovar Kentucky chicken isolates were compared with those of chicken isolates ...
Dhareshwar Sundeep S - - 2009
The kinetics of conversion of C-hydroxymethyl derivatives of pharmaceutically relevant beta-dicarbonyl carbon acids of two series, pyrazolidin-3,5-diones and inden-1,3-diones, and a model carbon acid back to the respective carbon acids were studied as a function of pH at 25 degrees C and an ionic strength of 0.15 M. This is ...
Gambon D L - - 2009
OBJECTIVE: To determine the erosive potential of seven different commercially available candy sprays in vitro and in vivo. MATERIAL AND METHODS: The erosive potential was determined in vitro by measuring the pH and neutralisable acidity. The salivary pH and flow rate were measured in healthy volunteers after administration of a ...
Holbrook W P - - 2009
Dental erosion is caused by dietary or gastric acid. This study aimed to examine the location and severity of tooth erosion with respect to causative factors, and to determine whether the clinical pattern of erosion reflected the dominant etiological factor. The study involved 249 Icelandic individuals and included: a detailed ...
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