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Molar Concentrations (molar + concentration)
Selected AbstractsKinetics and mechanism of adducts formation of tetraaza cobalt(II) complexes with some organic bases in DMF solventINTERNATIONAL JOURNAL OF CHEMICAL KINETICS, Issue 3 2007Mozaffar Asadi The kinetics and mechanism of the adduct formation of two Co(II) tetraaza complexes, [Co(ampen)] {[(N,N,-ethylenebis-(o -amino-,-phenylbenzylideneiminato)cobalt(II)]} and [Co(campen)] {[(N,N,-ethylenebis-(5-chloro- o -amino-,-phenylbenzylideneiminato)cobalt(II)]}, with four organic bases, 4-nitro imidazole (4-NO2Imid), 4-methyl imidazole (4-MeImid), imidazole (Imid), and 1-methyl imidazole (1-MeImid), in DMF were studied spectrophotometrically. The kinetic parameters and the second-order k2 rate constants show the following nucleophilicity trend of the bases toward the given substrate: 4-NO2Imid > 4-MeImid > Imid > 1-MeImid. The linear plots of kobs vs. the molar concentration of the base, the high span of k2 values, and the large negative values of ,S, suggest an associative (A) mechanism. © 2007 Wiley Periodicals, Inc. 39: 137,144, 2007 [source] A Hypothesis for the Chemical Basis for Perception of Sour TasteJOURNAL OF FOOD SCIENCE, Issue 2 2005Suzanne D. Johanningsmeiner ABSTRACT: Sour taste has been considered the simplest of the basic tastes because it is elicited only by hydrogen ions. However, there is not a sufficiently clear understanding of that relationship to allow sour taste intensity to be predicted and rationally modified in foods. On the basis of analysis of sensory data from our laboratory and reanalysis of previously published data, we propose a new hypothesis for the chemical basis for sour taste perception: The intensity of sour taste perception in acid solutions or acidified foods is linearly related to the molar concentration of all organic acid species with at least 1 protonated carboxyl group plus the molar concentration of free hydrogen ions. This hypothesis implies that, on a molar basis, different organic acids will be equally sour, provided at least 1 carboxyl group is protonated. The major effect of pH on sour taste will be to determine the degree of protonation of organic acids. If this hypothesis is confirmed, it will provide a new understanding of the chemical basis for this basic taste perception and have broad usefulness in the formulation of products in which sour taste is an important component of flavor. [source] Effects of oral administration of extracts of Hypericum perforatum (St John's wort) on brain serotonin transporter, serotonin uptake and behaviour in miceJOURNAL OF PHARMACY AND PHARMACOLOGY: AN INTERNATI ONAL JOURNAL OF PHARMACEUTICAL SCIENCE, Issue 12 2004Kazufumi Hirano The pharmacological effects of extracts of Hypericum perforatum (St John's wort) were characterized in-vitro and ex-vivo, in relation to its behavioural effects. In in-vitro experiments, St John's wort inhibited brain synaptosomal [3H]serotonin uptake in mice with little effect on specific [3H]paroxetine binding. For selective serotonin-reuptake inhibitors (SSRIs), the IC50 value for [3H]serotonin uptake (molar concentration of unlabelled drug necessary to displace 50% of specific uptake) correlated well with the inhibition constant Ki value for [3H]paroxetine binding in mouse brain. Oral administration of St John's wort (900 mg kg,1), paroxetine (1 mg kg,1) and sertraline (10 mg kg,1) brought about significant increases in the Km value for [3H]serotonin uptake into brain synaptosomes 4 h later, and only SSRIs suppressed specific [3H]paroxetine binding in mouse brain. St John's wort and SSRIs significantly inhibited marble-burying behaviour in mice and the time-course of attenuation of this behaviour by St John's wort was similar to that of [3H]serotonin uptake inhibition. In the forced swimming test, St John's wort, but not SSRIs, suppressed the immobility time of mice after oral administration. These results provide the first in-vivo evidence to suggest that the mode of antidepressant action of St John's wort differs from that of SSRIs. Thus, this study may have a significant impact on phytotherapy with St John's wort. [source] Cycloadditions in mixed aqueous solvents: the role of the water concentration,JOURNAL OF PHYSICAL ORGANIC CHEMISTRY, Issue 8 2005Theo Rispens Abstract We examined the kinetics of a series of cycloaddition reactions in mixtures of water with methanol, acetonitrile and poly(ethylene glycol) (MW 1000). The reactions include the Diels,Alder (DA) reaction between cyclopentadiene and N - n -butylmaleimide or acridizinium bromide, the retro-Diels-Alder (RDA) reaction of 1,4,4a,9a-tetrahydro-4a-methyl-(1,,4,,4a,,9a,)-1,4-methaneanthracene-9,10-dione and the 1,3-dipolar cycloaddition of benzonitrile oxide with N - n -butylmaleimide. Plots of logk vs the molar concentration or volume fraction of water are approximately linear, but with a characteristic break around 40,M water. This break, absent for the RDA reaction, is ascribed to hydrophobic effects. Comparison with aqueous mixtures of the more hydrophobic 1-propanol shows that these mixtures induce qualitatively similar effects on the rate, but that preferential solvation effects cause the mixtures of 1-propanol to exhibit a more complex behavior of logk on composition. The results are analyzed using the Abraham,Kamlett,Taft model. The solvent effects in aqueous mixtures are not satisfactorily described by this model. For some cycloadditions, small maxima in rate are observed in highly aqueous mixtures of alcohols. The origin of these maxima and the aforementioned breaks is most likely the same. Copyright © 2005 John Wiley & Sons, Ltd. [source] The inhibition of blood coagulation by heparins of different molecular weight is caused by a common functional motif,the C-domainJOURNAL OF THROMBOSIS AND HAEMOSTASIS, Issue 5 2003R. Al Dieri Summary.,Background:,Heparins in clinical use differ considerably as to mode of preparation, molecular weight distribution and pharmacodynamic properties. Objectives:,Find a common basis for their anticoagulant action. Methods:,In 50 fractions of virtually single molecular weight (Mr), prepared from unfractionated heparin (UFH) and four low-molecular-weight heparins (LMWH), we determined: (i) the molar concentration of material (HAM) containing the antithrombin binding pentasaccharide (A-domain); (ii) the specific catalytic activity in thrombin and factor Xa inactivation; (iii) the capacity to inhibit thrombin generation (TG) and prolong the activated partial thromboplastin time (APTT). We also calculated the molar concentration of A-domain with 12 sugar units at its non-reducing end, i.e. the structure that carries antithrombin activity (C-domain). Results:,The antithrombin activity and the effects on TG and APTT are primarily determined by the concentration of C-domain and independent of the source material (UFH or LMWH) or Mr. High Mr fractions (>15 000) are less active, probably through interaction with non-antithrombin plasma proteins. Anti-factor Xa activity is proportional to the concentration of A-domain, it is Ca2+ - and Mr-dependent and does not determine the effect on TG and APTT. Conclusion:,For any type of heparin, the capacity to inhibit the coagulation process in plasma is primarily determined by the concentration of C-domain, i.e. the AT-binding pentasaccharide with 12 or more sugar units at its non-reducing end. [source] Electrospray mass spectrometric investigation of the binding of cis -parinaric acid to bovine beta-lactoglobulin and study of the ligand-binding site of the protein using limited proteolysisRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 22 2003Tímea Imre The binding property of parinaric acid, a polyunsaturated fatty acid, to bovine , -lactoglobulin, has been studied by electrospray ionization mass spectrometry. Stable complexation was observed under acidic conditions in a molar ratio of 1:1. Competitive complexation experiments were performed using saturated and unsaturated fatty acid standards with different chain lengths and number of double bonds to study the specificity of the interaction. It can be concluded that formation of the parinaric acid,lactoglobulin complex is preferred even if the molar concentration of the other fatty acids is ten times higher. In cases of specific complex formation the protein must have an active site that is a good acceptor for the ligand molecule. Limited trypsinolysis was performed on the lactoglobulin molecule to identify which part is responsible for the complexation. An intermediate tryptic fragment with molecular mass of 5200,Da was found to have the same ability to bind parinaric acid as the intact protein. This disulfide-bonded residue, [41-70]S-S[149-162], might thus be involved in the specific complexation of parinaric acid to , -lactoglobulin. This conclusion is consistent with previous information on this binding site. Copyright © 2003 John Wiley & Sons, Ltd. [source] A New Amphiphilic Derivative, N -{[4-(Lactobionamido)methyl]benzylidene}- 1,1-dimethyl-2-(octylsulfanyl)ethylamine N -Oxide, Has a Protective Effect Against Copper-Induced Fulminant Hepatitis in Long,Evans Cinnamon Rats at an Extremely Low Concentration Compared with Its Original Form , -Phenyl- N -(tert -butyl) NitroneCHEMISTRY & BIODIVERSITY, Issue 9 2007Taketoshi Asanuma Abstract An amphiphilic , -phenyl- N- (tert -butyl) nitrone (PBN) derivative, N -{[4-(lactobionamido)methyl]benzylidene}-1,1-dimethyl-2-(octylsulfanyl)ethylamine N -oxide (LPBNSH), newly synthesized from its original form PBN in hopes of clinical use, was intraperitoneally administered to Long,Evans Cinnamon (LEC) rats every 2 days at the concentrations of 0.1, 0.5, 1.0, and 2.0,mg/kg. We found that LPBNSH protected against copper-induced hepatitis with jaundice in LEC rats at concentrations of 0.1 and 0.5,mg/kg, which were extremely low compared with that of PBN. It also effectively prevented the loss of body weight, reduced the death rate, and suppressed the increase in serum aspartate aminotransferase and alanine aminotransferase values arising from fulminant hepatitis with jaundice at the same concentrations. Similar results were observed when PBN was administered at the concentration of 150,mg/kg. Immunohistochemical analysis of 8-hydroxy-2,-deoxyguanosine and measurement of thiobarbituric acid-reactive substances in the liver showed that LPBNSH largely suppressed the formation of these oxidative products at same concentrations. No difference in the abnormal accumulation of copper in the liver between the LPBNSH administered and control groups was observed. From these results, it was concluded that LPBNSH exhibited liver-protective effects against fulminant hepatitis with jaundice at ca. 1/1000, 500 the molar concentration of PBN and, therefore, was clinically promising. [source] Development of a Method for the Quantification of the Molar Gold Concentration in Tumour Cells Exposed to Gold-Containing DrugsCHEMMEDCHEM, Issue 5 2007Ingo Ott Dr. Abstract The knowledge of the cellular molar concentration of a drug is an extremely important parameter for the discussion and interpretation of its efficacy and bioavailability. Concerning metal complexes, electrothermal atomic absorption spectroscopy (ETAAS) offers a valuable analytical tool. However, matrix effects often hamper proper quantification of the metal concentration in biological tissues. This paper describes the development of an ETAAS method for the quantification of the molar gold concentration in HT-29 colon carcinoma cells. ETAAS analytical conditions were optimised and a factor was developed which allows the calculation of the molar cellular gold concentration from the measured gold per cellular biomass value. The method was used to quantify the gold content in HT-29 cells after exposure to the gold drug auranofin. Results indicated a strong cellular uptake of auranofin (compared to other metal anticancer drugs), which significantly correlated with the antiproliferative effects triggered by this agent. [source] Structure,fungitoxicity relationships of some volatile flavour constituents of the edible mushrooms Agaricus bisporus and Pleurotus floridaFLAVOUR AND FRAGRANCE JOURNAL, Issue 4 2001Eugene Sebastian J. Nidiry Abstract The fungitoxicity of the diethyl ether extracts of two basidiomycete mushrooms, Agaricus bisporus and Pleurotus florida, and 14 flavour constituents present in these mushrooms is being reported. Median effective molar concentrations (EC50) of the compounds for the mycelial growth inhibition of Colletotrichum gloeosporioides on potato,dextrose,agar (PDA) medium were computed and compared. Among the constituents tested for fungitoxicity, 1-octanol exhibited the highest activity. Structure,activity relationship studies of the constituents revealed that high hydrophobicity of the alkyl moiety, the presence of the primary alcoholic group and the absence of branching of the alkyl group are responsible for the high activity of 1-octanol. Copyright © 2001 John Wiley & Sons, Ltd. [source] The analytical resolution of parallel first- and second-order reaction mechanismsINTERNATIONAL JOURNAL OF CHEMICAL KINETICS, Issue 9 2010N. B. Caballero Given the species A1 and A2, the competition among the three different elementary processes (1) (2) (3) is frequently found in thermal and photochemical reaction systems. In the present paper, an analytical resolution of the system (1),(3), performed under plausible contour conditions, namely, finite initial molar concentrations for both reactants, [A2]0 and [A1]0, and nonzero reaction rate coefficients k1, k2, and k3, leads to the equation [A1] = ((,[A2], , [A2])/,) , ,, where , = k1/2k3, , = , + 1 = 2k3/k2, and , = ([A2]0 + ,[A1]0 + , ,))/[A2]0,. The comparison with a numerical integration employing the fourth-order Runge,Kutta algorithm for the well-known case of the oxidation of organic compounds by ferrate ion is performed. © 2010 Wiley Periodicals, Inc. Int J Chem Kinet 42: 562,566, 2010 [source] Relationships Between Concentrations of Cocaine and Its Hydrolysates in Peripheral Blood, Heart Blood, Vitreous Humor and UrineJOURNAL OF FORENSIC SCIENCES, Issue 2 2006Wayne C. Duer Ph.D. ABSTRACT: Cocaine is known to degrade in vivo and in vitro by several hydrolytic mechanisms. A previous study found that the initial amount of cocaine added to plasma could be accounted for by summing the molar concentrations of cocaine's hydrolysis products and the cocaine remaining after hydrolysis. The present study was undertaken to investigate whether or not relationships might exist between such molar concentration sums for different postmortem bodily fluids. Determinations of cocaine, benzoylecgonine, ecgonine methyl ester, and ecgonine were performed using liquid chromatography/mass spectrometry (LC/MS/MS) with heart blood, femoral blood, vitreous humor (VH), and urine (UR). The results demonstrate a strong correlation between blood and VH concentrations (correlation coefficients of 0.88,0.94), weak correlation between the UR and blood concentrations (correlation coefficients of 0.61,0.64), and weak correlation between UR and VH concentrations (correlation coefficient of 0.59). The results demonstrate that ecgonine is a significant hydrolysate with concentrations on the same order of magnitude as benzoylecgonine. The results are consistent with rapid distribution of the parent drug and its hydrolysates in the blood and VH. The strong correlation between the blood and VH demonstrates that VH is an important medium for toxicology testing when attempting to make a determination of cocaine intoxication. [source] Effect of Lewis acids on the Diels,Alder reaction in ionic liquids with different activation modesJOURNAL OF PHYSICAL ORGANIC CHEMISTRY, Issue 4 2008Ana Vidi Abstract The Diels,Alder reaction has been examined in room temperature ionic liquids with high molar concentrations of Lewis acids under various conditions. A molar ratio of 10% catalyst gave a large increase in the selectivity and the yield of the reaction. The effect of catalysts on reaction rates was also examined under 100,MPa of pressure which leads to modest improvements in reaction rates. Ultrasound and microwave dielectric heating were also shown to improve the rate and, to a minor extent, selectivity of the examined reactions. Copyright © 2008 John Wiley & Sons, Ltd. [source] The production of high polymer to surfactant microlatexesJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 1 2010Raul P. Moraes Abstract Starved-feed microemulsion polymerization of styrene was investigated. The influence of the type (SDS or Dowfax 2A1) and concentration of anionic surfactant on the final particle size of latex made by the polymerization of microemulsions of styrene was studied. In addition, the influence of 1-pentanol and acrylic acid as cosurfactants was examined. Latexes with 20% solids content and polymer to surfactant ratio of 22 were produced, with a particle diameter of 42 nm and very low polydispersity indexes. Smaller particles are produced using SDS than Dowfax 2A1 for the same weight fraction of surfactant; however, similar particle sizes were obtained with the same molar concentrations of SDS and Dowfax 2A1. Further shot additions of monomer increased solids level as high as 40% and polymer to surfactant ratios greater than 40, with particles remaining monodisperse with average diameter smaller than 60 nm. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 48,54, 2010 [source] Analysis of segregation process of n -alkanes in binary mixtures by FTIR and Raman spectroscopyJOURNAL OF RAMAN SPECTROSCOPY, Issue 11 2005Andrzej Hacura Abstract In the FTIR and Raman spectroscopic studies, the phenomena of normal n -alkanes segregation in the binary mixtures of solid-state paraffin at room temperature were examined. Samples, in which one of the ingredients had been deuterated were prepared in different molar concentrations. Components of the mixture separated in time, creating separate domains, were observed in the changing of shape of infrared and Raman bands. The process of segregation depended on the difference of the chains' length of the mixture's ingredients and the molar fraction, in which the mixtures were prepared. The size of the created microdomains has been estimated based on the model describing shape and the splitting of the IR bands developed by Hiebert and Hornig. By applying the micro-Raman imaging technique, a number of surface maps have been obtained indicating the separating process of ingredients of the mixtures. This allowed comparing and verifying time dependent results of the IR study. Copyright © 2005 John Wiley & Sons, Ltd. [source] Raman spectroscopy and multivariate curve resolution of concentrated Al2O3,Na2O,H2O solutionsJOURNAL OF RAMAN SPECTROSCOPY, Issue 6 2003Jon R. Schoonover Abstract Multivariate curve resolution was applied to a series of Raman spectra for samples representing highly concentrated alkaline aluminate slurries. Factors are extracted that represent the behavior of the dominant chemical species present, including aluminate monomer, aluminate oligomers, water and hydroxide. The analysis is particularly useful in unraveling the numerous overlapping contributions in the ,(OH) region of the spectrum. These extracted factors were further examined by comparing their scores with measured physiochemical properties such as density, relative humidity and molar concentrations of components, weight fractions and water activity. Published in 2003 by John Wiley & Sons, Ltd.. [source] A Mutation in Mitochondrial Complex I Increases Ethanol Sensitivity in Caenorhabditis elegansALCOHOLISM, Issue 4 2003Ernst-Bernhard Kayser Background: The gene gas-1 encodes the 49-kDa subunit of complex I of the mitochondrial electron transport chain in Caenorhabditis elegans. A mutation in gas-1 profoundly increases sensitivity to ethanol and decreases complex I-dependent metabolism in mitochondria. Methods: Mitochondria were isolated from wild-type and gas-1 strains of C. elegans. The effects of ethanol on complex I-, II-, and III-dependent oxidative phosphorylation were measured for mitochondria from each strain. Reversibility of the effects of ethanol was determined by measuring oxidative phosphorylation after removal of mitochondria from 1.5 M ethanol. The effects of ethanol on mitochondrial structure were visualized with electron microscopy. Results: We found that ethanol inhibited complex I,, II,, and III,dependent oxidative phosphorylation in isolated wild-type mitochondria at concentrations that immobilize intact worms. It is important to note that the inhibitory effects of ethanol on mitochondria from either C. elegans or rat skeletal muscle were reversible even at molar concentrations. Complex I activity was lower in mitochondria from gas-1 animals than in mitochondria from wild-type animals at equal ethanol concentrations. Complex II activity was higher in gas-1 than in wild-type mitochondria at all concentrations of ethanol. No difference was seen between the strains in the sensitivity of complex III to ethanol. Conclusions: The difference in ethanol sensitivities between gas-1 and wild-type nematodes results solely from altered complex I function. At the respective concentrations of ethanol that immobilize whole animals, mitochondria from each strain of worms displayed identical rates of complex I-dependent state 3 respiration. We conclude that a threshold value of complex I activity controls the transition from mobility to immobility of C. elegans. [source] Occupational immediate-type asthma and rhinitis due to rhodium saltsAMERICAN JOURNAL OF INDUSTRIAL MEDICINE, Issue 1 2010Rolf Merget MD Abstract Background Whereas platinum salts are well known occupational allergens, rhodium salts have not been identified as inhalative sensitizing substances. Methods A 27-year-old atopic operator of an electroplating plant developed work-related shortness of breath and runny nose with sneezing after exposure to rhodium salts. Quantitative skin prick tests (SPT) and bronchial challenge tests with a dosimeter protocol were performed with quadrupling doses of the sodium chloride salts of rhodium (Na3RhCl6) and platinum (Na2PtCl6). Results The patient showed positive SPT reactions and positive bronchial immediate-type reactions with rhodium and platinum salts. Sensitivity to rhodium salt was much higher than to platinum salt; the molar concentrations differed by a factor of 256 in SPT and a factor of 16 in bronchial challenges. Conclusions Rhodium salts should be considered as occupational immediate-type allergens. Am. J. Ind. Med. 53:42,46. 2010. © 2009 Wiley-Liss, Inc. [source] Cryopreservation of isolated blastomeres and embryonic stem-like cells of Leopard danio, Brachydanio frankeiAQUACULTURE RESEARCH, Issue 4 2010Padmanav Routray Abstract This study aimed at developing a suitable cryopreservation protocol for embryonic stem (ES)-like cells of a tiny freshwater fish Leopard danio (Brachydanio frankei). Embryonic stem (ES)-like cells derived from blastomeres of the early blastulae stage of the developing embryo were cultured in vitro in a medium containing Leibowitz-15 supplemented with 10% foetal bovine serum, leopard danio embryo extract, sodium bicarbonate, sodium selenite, basic fibroblast growth factor, epidermal growth factor and leukaemia inhibitory factor. The ES-like cells showed properties similar to ES cells in other species. They were morphologically small, round to polygonal and present in patches and extensively expressed alkaline phosphatase and stage-specific embryonic antigen. The toxicity and chilling sensitivity of these cells were determined using ethylene glycol (EG), propylene glycol (PG) and glycerol as cryoprotective agents at molar concentrations of 0.6, 1.0, 1.4, 1.8 and 2.0. Among them, 1.8 M EG showed 70% significant viable ES-like cells (P<0.05). The post-thawed cells retained similar properties of non-cryopreserved ES-like cells with a viability rate of 65%. Similarly, blastomeres cryopreserved following the slow cooling rate with EG and PG yielded a viability of more than 70%. [source] | |||||||||||||