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Xiao Feng - - 2011
A sensitive liquid chromatographic-mass spectrometric technique coupled with liquid-liquid extraction method was developed and validated for simultaneous determination of dehydro-tumulosic acid, tumulosic acid and polyporic acid C in rat plasma. The analytes were separated on a Kromasil C(18) column with a total running time of 12.5min. Author had compared the ...
Jochym Kamila - - 2011
BACKGROUND: New starch preparations were produced by thermolysis of potato starch in the presence of inorganic (hydrochloric) and organic (citric and tartaric) acids under controlled conditions. The starch preparations were physicochemically and structurally characterised and analysed for their resistance to enzymatic digestion in vitro. RESULTS: The content of resistant fraction ...
Notghi Alp - - 2011
TauroH-23-((75)Se)selena-25-homocholic acid (SeHCAT) retention has been used for the diagnosis of bile acid malabsorption since the early 1980s. Bile acid malabsorption has been increasingly recognized as an important cause of severe chronic diarroea with subsequent increase in the number of referrals for the SeHCAT test. In this study, we review ...
Shen Su Fen - - 2011
Under certain acidic condition, thioglycolic-acid-modified gold nanoparticles (Au-NPs) can react with melamine, resulting in the aggregation of Au-NPs through electrostatic interactions between -COO(-) groups on the surface of Au-NPs and -NH3+ groups of melamine. The aggregation extent depends on the concentration of melamine, which can be validated by SEM imaging ...
Samanta Debasis - - 2011
A simple and convenient method to prepare acid-responsive microcapsules by using functionalized single-walled carbon nanotubes and ytterbium triflate has been developed. Fluorescence active compounds were "pre-loaded" or "post-loaded" in the microcapsules and released later in acidic medium. An interesting "zip-unzip" phenomenon was observed while filming the action of acid on ...
Trader Darci J - - 2011
Although the carboxylic acid moiety is prevalent in many biologically produced molecules, including natural products and proteins, methods to chemoselectively target this functional group have remained elusive. Generally, strategies that utilize carboxylate nucleophilicity also promote reactions with other nucleophiles such as amines and hydroxyls. A reagent was sought to facilitate ...
Batran Sa-E - - 2011
Abstract Acid mucins have diagnostic significance for many pathological conditions, especially in certain tumors. We compared the classical pH 2.5 Alcian blue method to a new, improved zirconyl hematoxylin (IZH) method for demonstrating acid mucins using two fixatives: Bouin`s solution and 10% neutral buffered formalin (NBF). We used rabbit small ...
Takenaka Yuko - - 2011
Glycolic acid chemical peeling is effective for treating comedones, and some clinical data show that it also improves inflammatory eruptions. The purpose of this study was to identify the mechanism of glycolic acid chemical peeling to improve inflammatory acne. To assess growth inhibitory and bactericidal effects of glycolic acid on ...
Leonard Nicholas M - - 2011
A method for the in situ formation of N-trifluoroacetoxy succinimide (TFA-NHS) and its application in the formation of succinimidyl esters is presented. The developed method provides N-trifluoroacetyl and N-maleoyl amino acid succinimidyl esters from a variety of amino acids using a one-pot, high yielding protocol. Investigations into the formation of ...
Guan Wenna - - 2011
Simple and rapid quantitative determination of fatty-acid-based biofuels is greatly important for the study of genetic engineering progress for biofuels production by microalgae. Ideal biofuels produced from biological systems should be chemically similar to petroleum, like fatty-acid-based molecules including free fatty acids, fatty acid methyl esters, fatty acid ethyl esters, ...
Zhao Yingjie - - 2011
A rotaxane incorporating three different stations and fluorescent states (output) was prepared. The movement of the macrocycle can be easily detected by fluorescence change as an output signal and the macrocycle could be easily controlled to locate on three different stations of the thread by the tuning of acid/base (input).
Nazemi M K - - 2011
Effective recovery of nickel (Ni) from spent NiO/Al(2)O(3) catalyst in a simple hydrometallurgical route is suggested. Nickel recovery of 99.5% was achieved with sulfuric acid leaching. The leach liquor was partly neutralized and nickel ammonium sulfate was precipitated by adding ammonia. The nickel in the supernatant was concentrated by solvent ...
Kitanovski Zoran - - 2011
In this comment we want to draw attention to some weaknesses of the analytical method used for quantification of the organosulfates, which are influencing the end results, and thus the conclusions. We also try to suggest some possible improvements on the basis of our experience and knowledge.
Andrási N - - 2011
An exhaustive GC-MS acquisition study was performed, for the simultaneous analysis of natural and synthetic steroids and cholic acids (in order to insert them into the last tierce of our multiresidue analysis system), such as androsterone, β-estradiol, transdehydroandro-sterone, transdehyroandrosterone, mestranol, dihydrotestosterone, ethinylestradiol, testosterone, norethisterone, estriol, 4-androstene-3,17-dione, gestodene, levonorgestrel, etonogestrel, coprostanol, ...
McCubbin J Adam - - 2011
An efficient and simple catalytic method for the isomerization of readily prepared allylic alcohols is described. We focus particularly on cyclic examples and the synthesis of unusual enyne and dienols. The benzoic acid catalysts employed are commercially available, very inexpensive and can be tuned for reactivity and substrate sensitivity.
Huang Gangliang - - 2011
The alkali-insoluble (1 → 3)-β-d-glucan was prepared by alkaline-acid method and followed deproteinization by alkaline method using yeast cell wall as the starting material. The deproteinized product was characterized by infrared (IR) spectroscopy, and the polysaccharide components were analysed by paper chromatography. It indicated that the alkaline-acid method was an ideal way ...
MichaƂowski Tadeusz - - 2011
The isohydricity (pH constancy) principle is referred to the pair of solutions: weak acid (HL, C(0)mol/L) and strong acid (HB, Cmol/L) when mixed e.g., according to titrimetric mode. Such a case takes place if the relation C(0)=C+C(2)×10(pK(1)) is valid, where pK(1)=-logK(1), K(1) - dissociation constant for a weak monoprotic acid ...
Trincado Mónica - - 2011
Several polyols, which are easily available from sugars through biochemical conversion or hydrogenolytic cleavage, are directly converted into carboxylic acids and amides. This efficient dehydrogenative coupling process, catalyzed by a rhodium(I) diolefin amido complex, is an attractive approach for the production of organic fine chemicals from renewable resources. This method ...
Tan Fuyuan - - 2011
In this paper, a novel application of alternating penalty trilinear decomposition (APTLD) for high performance liquid chromatography with fluorescence detector (HPLC-FLD) has been developed to simultaneously determine the contents of free amino acids in tea. Although the spectra of amino acid derivatives were similar and a large number of water-soluble ...
Kurpad Anura V - - 2011
There are now different stable isotopic methods to measure minimum daily human indispensable amino acid (IAA) requirements. There has been debate on the appropriateness of statistical methods used to define the nature of change in the response. Current isotopic methods measure daily amino acid oxidation and balance of the IAA ...
Kim Jong Min - - 2011
This study demonstrates a new approach for the highly selective molecular recognition of chiral mandelic acid using an L-mandelic acid derivative with an optically active hydroxyl group as the selector. The proposed method is based on quartz crystal microbalance (QCM) detection combined with functional multilayer film techniques in a liquid ...
Bigelow Nicholas W - - 2011
Fatty acid analysis is essential to a broad range of applications including those associated with the nascent algal biofuel and algal bioproduct industries. Current fatty acid profiling methods require lengthy, sequential extraction and transesterification steps necessitating significant quantities of analyte. We report the development of a rapid, microscale, single-step, in ...
Xu Yanping - - 2011
A rapid and comprehensive qualitative method has been developed to characterize the different classes of polyphenols, such as anthocyanins, flavonols, phenolic acids and flavanols/proanthocyanidins, in grape products. The detection was achieved by two runs with same LC gradient in different MS ionization modes and mobile phase modifiers (positive ionization mode ...
Bloom Steven - - 2011
The selective α,α-difluorination of carbonyl compounds remains a challenge in modern organic synthesis; current methods often incorporate stepwise processes and/or harsh conditions, providing unsatisfactory mixtures of mono- and difluorinated products. In this communication, a practical, mild, and one-pot method for the selective α,α-difluorination of readily available acid chlorides is reported ...
Komoriya Tomoe - - 2011
Various convenient and high-sensitivity immunoassays based on luminescent oxygen channeling and chromatographic techniques have been developed in recent years. This study focused on the latex agglutination immunoassay because it is a simple, homogenous immunoassay, which is also cost effective. We developed a highly sensitive latex reagent and examined the method ...
Baptista Mafalda S - - 2011
A capillary electrophoretic method for the determination of the amino acid β-N-methylamino-l-alanine (BMAA) was achieved using a fused-silica capillary column (50 cm × 75 μm I.D.) filled with 5 mM sodium tetraborate solution (pH 9), with an applied voltage of 25 kV, at 25 °C. The method was then applied in quantifying BMAA in eighteen strains of ...
Yang Xing - - 2011
A new method for catalytic nonenzymatic kinetic resolution of α-substituted alkanoic acids has been developed, which relies on their activation with DCC followed by enantioselective alcoholysis of the intermediate symm-anhydrides in the presence of the amidine-based catalyst homobenzotetramisole (HBTM). Moderate to excellent selectivity factors (s=5-96) have been obtained in the ...
Zhu Shujie - - 2011
C-Acylimines 1 undergo intermolecular amidation with amides 2 to produce monoacyl gem-diamino acid derivatives 3 upon treatment with Cu(OTf)(2) (20 mol %)/ PPh(3) (20 mol %) under mild conditions. This method provides an efficient access to gem-diamino acid equivalents with good to excellent yields.
Williams Caroline M - - 2011
Triacylglycerides (TAGs) are the most important stored energy reserve in eukaryotes and are regularly measured in insects. Quantitative analysis of TAGs is complicated by their diversity of structure, and there are concerns with the quantitative accuracy of commonly used analytical methods. We used thin layer chromatography coupled to a flame ...
Genady Afaf R - - 2011
An efficient method for synthesis of cyclohexyl and cyclohexenyl α-amino acids via palladium-catalyzed three-component assemblies followed by ring-closing metathesis (RCM) is described. The present catalytic reaction is successfully extended to substituted benzylidene azlactones 2a-j RCH=(1,3-oxazole): R = alkyl or aryl. The amphiphilic bis-allylation of these substrates has been achieved by ...
Tai Akihiro - - 2011
6-O-Dodecanoyl-2-O-α-d-glucopyranosyl-l-ascorbic acid (6-sDode-AA-2G) was synthesized from 2-O-α-d-glucopyranosyl-l-ascorbic acid and lauric anhydride with a polymer catalyst, poly(4-vinylpyridine), in N,N-dimethylformamide without the introduction of protecting groups. The optimum reaction conditions enabled 6-sDode-AA-2G to be synthesized in a yield of 49.7%. The yield and the regioselectivity in this method were far superior to ...
Vijaya Bharathi D - - 2011
A highly sensitive, selective and evaporation free SPE extraction, ESI-LC-MS/MS method has been developed for estimation of misoprostol free acid in human plasma using misoprostol acid-d(5) as an internal standard (IS). The analyte was separated using isocratic mobile phase on reverse phase column and analyzed by MS/MS in the multiple ...
Lipping Lauri - - 2011
The gas-phase acidities of ca 60 monosubstituted anilines (with acidity span of almost 50 kcal mol-1) have been calculated using density functional theory (DFT) at B3LYP/6-311+G** level. At this relatively simple level of theory the calculated (DGcalc) and available experimental (DGexp) acidities are in a reasonable quantitative correlation according to ...
Bumbu Valentina D - - 2011
The first catalytic, nonenzymatic kinetic resolution of β-lactams has been achieved. Alcoholysis of their N-aroyl derivatives in the presence of a simple chiral acyl transfer catalyst, benzotetramisole, produces β-amino acid derivatives with excellent enantioselectivity.
Visser Wouter F - - 2011
d-Amino acids are increasingly being recognized as important signaling molecules in mammals, including humans. d-Serine and d-aspartate are believed to act as signaling molecules in the central nervous system. Interestingly, several other d-amino acids also occur in human plasma, but very little is currently known regarding their function and origin. ...
Hathwar Venkatesha R - - 2011
An extension of the supramolecular synthon-based fragment approach (SBFA) method for transferability of multipole charge density parameters to include weak supramolecular synthons is proposed. In particular, the SBFA method is applied to C-H···O, C-H···F, and F···F containing synthons. A high resolution charge density study has been performed on 4-fluorobenzoic acid ...
Adedokun S A - - 2011
Accurate estimation of ileal endogenous amino acid (EAA) losses is important when formulating diets on a standardized ileal digestible amino acid basis. In addition to the undigested and unabsorbed amino acids of dietary origin, amino acids of endogenous origin, which can be basal or diet specific, are found in digesta. ...
Held Patrice K - - 2011
Ion-exchange chromatography (IEC) is the most widely used method for amino acid analysis in physiological fluids because it provides excellent separation and reproducibility, with minimal sample preparation. The disadvantage, however, is the long analysis time needed to chromatographically resolve all the amino acids. To overcome this limitation, we evaluated a ...
Ano Yusuke - - 2011
The first catalytic alkynylation of unactivated C(sp3)-H bonds has been accomplished. The method allows for the straightforward introduction of an ethynyl group into aliphatic acid derivatives under palladium catalysis. This new reaction is applied to a rapid elaboration of complex aliphatic acids, for example, via azide/alkyne cycloaddition.
Beck Elizabeth M - - 2011
The application of chiral sulfinamides and achiral sulfonic acids as a cocatalyst system for enantioselective protonation reactions is described. Structurally simple, easily accessible sulfinamides were found to induce moderate-to-high ee's in the formation of 2-aryl-substituted cycloalkanones from the corresponding trimethylsilyl enol ethers.
Giovannozzi A M - - 2011
A porous silicon biosensor based on P450 enzyme for arachidonic acid detection was developed. A new transduction method is presented with a simultaneous measurement of refractive index and fluorescence intensity changes when the analyte is binding to an enzyme on the porous silicon surface. A fluorophore bound to a cysteine ...
Afiuni-Zadeh Somaieh - - 2011
Simple and efficient microwave-assisted acid hydrolysis (MAAH) of proteins was used for rapid quantification of α-aminoadipic semialdehyde (AAS) and γ-glutamic semialdehyde (GGS) as major protein oxidation markers. The precursor amino acid residues corresponding to AAS and GGS in oxidized proteins were derivatized by reductive amination with sodium cyanoborohydride (NaCNBH(3)) and ...
Li Baoshan - - 2011
Mesoporous silica pillared clay (SPC) materials with different contents of H(3)PW(12)O(40) (HPW) heteropoly acid were synthesized by introducing HPW into clay interlayer template in an acidic suspension using sol-gel method. Samples with similar HPW loadings were also prepared by impregnation method using SPC as the support. The results of the ...
Kiss Loránd - - 2011
A regio- and stereoselective approach to fluorinated β-aminocyclohexene or cyclohexane esters has been developed, starting from a bicyclic β-lactam (1). The procedure involves six or seven steps, based on regio- and stereoselective iodolactonization, lactone opening and hydroxy-fluorine exchange. The method has been extended to the synthesis of fluorinated amino ester ...
Quehenberger Oswald - - 2011
Historically considered to be simple membrane components serving as structural elements and energy storing entities, fatty acids are now increasingly recognized as potent signaling molecules involved in many metabolic processes. Quantitative determination of fatty acids and exploration of fatty acid profiles have become common place in lipid analysis. We present ...
Miller Benjamin L - - 2011
Nucleic acids were one of the first biological targets explored with DCC, and research into the application has continued to yield novel and useful structures for sequence- and structure-selective recognition of oligonucleotides. This chapter reviews major developments in DNA- and RNA-targeted DCC, including methods under development for the conversion of ...
Xiao Xiao - - 2011
This paper describes an effective chiral base-catalyzed biomimetic transamination of α-keto esters using simple benzyl amines. A wide variety of α-amino esters containing various functional groups can be synthesized in high enantioselectiv-ity and reasonable yield.
Strieglerová Lenka - - 2011
Electromembrane extraction (EME) proved to be a simple and rapid pretreatment method for analysis of amino acids and related compounds in body fluid samples. Body fluids were acidified to the final concentration of 2.5M acetic acid and served as donor solutions. Amino acids, present as cations in the donor solutions, ...
Hayamizu Kohsuke - - 2011
In nutrition studies, it is often of primary interest to determine the critical threshold value of some biological quantities. To determine the amino acid requirement, the tracer approach including the indicator amino acid oxidation method is useful for the investigation of human subjects. In this approach, measurements of amino acids ...
Reston Eg - - 2011
Purpose This article describes a minimally invasive technique for removal of intrinsic enamel stains and discoloration. The technique is based on enamel microabrasion with application of an acid-abrasive gel. Treatment may be complemented with composite resin to compensate for the effects of acid or to finish the masking effect.
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