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Excess Amount (excess + amount)
Selected AbstractsSPME/GC/MS and sensory flavour profile analysis for estimation of authenticity of thyme honeyINTERNATIONAL JOURNAL OF FOOD SCIENCE & TECHNOLOGY, Issue 2 2007Demet Manna Summary Volatiles of six commercially obtained thyme honey samples and a pure thyme honey sample were extracted and analysed by Solid phase micro extraction (SPME)/Gas chromatography (GC)/Mass spectrometry (MS) procedure. Excess amount of volatiles such as thymol (trace) and carvacrole (0.66%) that originate from thyme plants indicated adulteration by thyme essential oil in one of the commercial samples. Sensory flavour profile analysis showed that the flavour of pure thyme honey sample consisted of: sweet, honey, lilac, bitter almond, thyme, violet, waxy, sour, ginger, caramel and rose characters. Adulterated honey was detected to be the sweetest sample involving intense thyme flavour without honey character. 3,4,5-Trimethoxybenzaldehyde which is a volatile not found in other unifloral honeys, seems to be a possible marker, but further studies with certified thyme honey samples are necessary in order to confirm the utility of this compound in estimation of authenticity. [source] MCE enzyme immunoassay for carcinoembryonic antigen and alpha-fetoprotein using electrochemical detectionELECTROPHORESIS, Issue 19 2009Shusheng Zhang Abstract An MCE electrochemical enzyme immunoassay protocol for the determination of carcinoembryonic antigen (CEA) and alpha-fetoprotein (AFP) was reported. Two antigens (Ag), CEA and AFP, were incubated simultaneously with an excess amount of horseradish peroxidase-labeled antibody (Ab*). The free Ab* and the Ab*,Ag complex produced in the solution were first separated through a postcolumn reaction and then traced by the enzyme substrate o -aminophenol. The 3-aminophenoxazine produced in enzyme reaction was detected with downstream amperometric detection. The separations were performed at a separation voltage of +1.4,kV and were completed in less than 60,s. The better analytical performance and distinct miniaturization/portability for MCE at less assay time and sample volume consumption was achieved. The detection limit of CEA and AFP was calculated to be 0.25 and 0.13,ng/mL, respectively. Therefore, MCE could be used as a sensitive and new tool in separation science and offered considerable promise in biological sample analysis or quick clinical diagnosis. [source] A ,3 -Alkoxo-Bridged Tetranuclear [Cu4L2] Copper(II) Complex of a Hexadentate N2O4 Donor Ligand with a [6 + 0] Cu4O4 Cubane Core: Synthesis, Crystal Structure, and Magnetic PropertiesEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 22 2010Dipankar Maity Abstract A novel hexacoordinating non-Schiff base ligand (H4L) with N2O4 donor atoms has been synthesized by simple Mannich reactions. The use of this ligand with Cu(ClO4)2·6H2O in different molar ratios as well as pH leads to the formation of a mononuclear species and a tetranuclear CuII complex possessing a cubane [Cu4L2] core with almost equal Cu···Cu separation. In the presence of an excess amount of copper(II) ions and triethylamine at reflux, the mononuclear [CuH2L] species can be converted into the tetranuclear one, whereas the reverse process was not observed even after prolonged reaction time. Both the complexes have been characterized by single-crystal X-ray diffraction and magnetic measurements. Magnetic studies reveal that complex 1 displays a paramagnetic Curie-type behavior whereas 2 displays a singlet-spin ground state induced by strong intramolecular antiferromagnetic interactions. [source] An Unusual Anion,, Interaction in an ;rido Organometallic Assembly: Synthesis, First Crystal Structure, and Computational StudyEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 25 2009Jamal Moussa Abstract The organometallic assembly [Cp*Ir(,6 -C6H2O4)(BF2)2(CF3SO3)][Cp*Ir(,-Cl)3IrCp*] (3) was prepared from [Cp*Ir(solvent)3][OTf]2 (2) and 1,2,4,5 tetrahydroxybenzene (THB, 1) in acetone, in the presence of an excess amount of BF3·2H2O. Assembly 3 was fully characterized by multinuclear NMR spectroscopy. Remarkably, the X-ray molecular structure of 3 shows that an anion,, interaction occurs between the neutral component Cp*Ir(,6 -C6H2O4)(BF2)2 of the assembly and the CF3SO3 anion of the cationic species [Cp*Ir(,-Cl)3IrCp*]. Computational analysis was carried out on 3 to unravel the nature of this noncovalent interaction. Such an example could serve as a model to explain the important role of anions in organometallic chemistry and asymmetric catalysis. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009) [source] An Efficient Route to Group 6 and 8 Metallaborane Compounds: Synthesis of arachno -[Cp*Fe(CO)B3H8] and closo -[(Cp*M)2B5H9] (M = Mo, W)EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 11 2009K. Geetharani Abstract Reaction of [Cp*Fe(CO)2I] (Cp* = ,5 -C5Me5) with an excess amount of BH3·thf in toluene at 75 °C or with LiBH4 at ,78 °C leads to the isolation of hydrogen-rich ferraborane arachno -[Cp*Fe(CO)B3H8] in good yield. In a similar fashion, reaction of [Cp*M(CO)3Cl] (M = Mo and W) with an excess amount of BH3·thf at 80 °C or at ,78 °C with LiBH4 yielded metallaboranes [(Cp*M)2B5H9] (M = Mo, W). Isolated yields of closo -[(Cp*M)2B5H9], (M = Mo and W), both from LiBH4 and BH3·thf, are good. All compounds were characterized in solution by IR, 1H, 11B, and 13C NMR spectroscopy and mass spectrometry and the structural types were unequivocallyestablished by crystallographic analysis of arachno -[Cp*Fe(CO)B3H8].(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009) [source] Stability Constants and Dissociation Rates of the EDTMP Complexes of Samarium(III) and Yttrium(III)EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 30 2008Ferenc Krisztián Kálmán Abstract The stability constants of Sm(EDTMP) (log,KML = 20.71) and Y(EDTMP) (log,KML = 19.19) were determined by a competition reaction between the Ln3+ ion (Ln3+ = Sm3+ or Y3+) and Cu2+ for the EDTMP ligand by spectrophotometry at pH , 10, in the presence of an excess amount of citrate (0.15 M NaCl, 25 °C). For determining the stability constants of Cu(EDTMP) (log,KML = 19.36) and Ca(EDTMP) (log,KML = 8.71) pH,potentiometry was used. In the pH range 4,9 the EDTMP complexes are present in the form of nonprotonated and mono-, di- and triprotonated species. The Ca2+ ion forms a dinuclear complex with Ln(EDTMP). In a simplified blood plasma model consisting of Sm3+, Ca2+ and Zn2+ metal ions, EDTMP, citrate, cysteine and histidine ligands, Sm3+ is practically present in the form of [Sm(HEDTMP)Ca]2,, whereas Zn2+ predominantly forms [Zn(HEDTMP)]5, and [Zn(H2EDTMP)]4, complexes. For studying the dissociation rates of the complexes, the kinetics of the metal exchange (transmetallation) reactions between the Ln(EDTMP) complexes and Cu2+,citrate were investigated in the pH range 7,9 by the stopped-flow method. The rates of the exchange reactions are independent of the Cu2+ concentration and increase with the H+ concentration. The rate constants, characterizing the proton-assisted dissociation of the Ln(EDTMP) complexes, are several orders of magnitude higher than those of the similar Ln(EDTA) complexes, because the protonation constants of Ln(EDTMP) are high and the protonated Ln(HEDTMP) and Ln(H2EDTMP) species are present in higher concentration. The half-times of dissociation of Sm(EDTMP) and Y(EDTMP) at pH = 7.4 and 25 °C are 4.9 and 7.5 s, respectively. These relatively short dissociation half-time values do not predict the deposition of Ln3+ ions in bones in the form of intact Ln(EDTMP) complexes. It is more probable that sorption of the EDTMP ligand and Sm3+ or Y3+ ions occurs independently after the dissociation of complexes.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008) [source] Generation and Reactions of Overcrowded Diaryldilithiostannane and DiaryldipotassiostannaneEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 21 2005Tomoyuki Tajima Abstract Exhaustive reduction of an overcrowded dibromostannane bearing two bulky aromatic substituents, Tbt(Dip)SnBr2 {Tbt = 2,4,6-tris[bis(trimethylsilyl)methyl]phenyl; Dip = 2,6-diisopropylphenyl}, with an excess amount of lithium naphthalenide in THF at ,78 °C gave the corresponding dilithiostannane, Tbt(Dip)SnLi2, the generation of which was confirmed by trapping experiments with some electrophiles together with 119Sn and 7Li NMR spectroscopy. The diaryldilithiostannane was found to be stable in solution under an inert gas below ,25 °C. The potassium analogue, Tbt(Dip)SnK2, was also generated by the reduction of the dibromostannane in THF at ,78 °C by the use of KC8 as a reductant. The reactions of dilithiostannane and dipotassiostannane obtained with o -dibromobenzene did not give a stannacyclopropabenzene derivative but an unexpected cyclization product, a stannacyclobutabenzene derivative, in contrast to thereactions of the corresponding dilithiosilane and dilithiogermane, Tbt(Dip)ELi2 (E = Si, Ge), with o -dibromobenzene leading to the formation of the corresponding metallacyclopropabenzenes as stable crystalline compounds. A preliminary result of the synthesis of a tin,tellurium double-bond compound from the dilithiostannane is also presented. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005) [source] Synthesis of (1,2,4-Oxadiazole)palladium(II) Complexes by [2 + 3] Cycloaddition of Nitrile Oxides to Organonitriles in the Presence of PdCl2EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 5 2005Nadezhda A. Bokach Abstract The reaction between the nitrile oxides 2,4,6-R3C6H2CNO (R = Me, OMe) and trans -[PdCl2(RCN)2], or RCN (R = Me, Et, CH2CN, NMe2, Ph) in the presence of PdCl2, proceeded smoothly under mild conditions and allowed the isolation of the 1,2,4-oxadiazole complexes trans -[PdCl2{Na=C(R)-ON=Cb(C6H2R3)(Na,Cb)}2] (1,8) in 40,85,% yields. In CH2Cl2, the reaction between 2,4,6-R3C6H2CNO and [PdCl2(MeCN)2] furnishes [PdCl2(ONCC6H2R3)2] (9 and 10), which are the first representatives of metal compounds where nitrile oxides act as ligands. The 1,2,4-oxadiazole complexes 1,8 were characterized by elemental analysis, FAB mass spectrometry, and IR, 1H and 13C{1H} NMR spectroscopy, while 2, 3, 7, and 8 were additionally characterized by X-ray crystallography. The liberation of the heterocyclic species from 1,8 was successfully performed by substitution reaction either with 1,2-bis(diphenylphosphanyl)ethane or with an excess amount of Na2S·7H2O in MeOH; the liberated 1,2,4-oxadiazoles (11,18) were characterized by positive-ion FAB mass spectrometry and 1H and 13C{1H} NMR spectroscopy. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005) [source] Catalytic Asymmetric Alkylation of Aldehydes by Using TrialkylboranesEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 26 2008Takahiro Ukon Abstract Triethylborane can be used in the asymmetric alkylation of aldehydes by using a 3-(3,5-diphenylphenyl)-H8 -BINOL-derived titanium(IV) catalyst in the presence of an excess amount of titanium tetraisopropoxide. The reaction proceeds with a low catalyst loading (2 mol-%), exhibiting high enantioselectivity for aromatic and unsaturated aldehydes. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008) [source] Disruption of Cortical Microtubules by Overexpression of Green Fluorescent Protein-Tagged ,-Tubulin 6 Causes a Marked Reduction in Cell Wall SynthesisJOURNAL OF INTEGRATIVE PLANT BIOLOGY, Issue 1 2006David H. Burk Abstract It has been known that the transverse orientation of cortical microtubules (MTs) along the elongation axis is essential for normal cell morphogenesis, but whether cortical MTs are essential for normal cell wall synthesis is still not clear. In the present study, we have investigated whether cortical MTs affect cell wall synthesis by direct alteration of the cortical MT organization in Arabidopsis thaliana. Disruption of the cortical MT organization by expression of an excess amount of green fluorescent protein-tagged ,-tubulin 6 (GFP-TUA6) in transgenic Arabidopsis plants was found to cause a marked reduction in cell wall thickness and a decrease in the cell wall sugars glucose and xylose. Concomitantly, the stem strength of the GFP-TUA6 overexpressors was markedly reduced compared with the wild type. In addition, expression of excess GFP-TUA6 results in an alteration in cell morphogenesis and a severe effect on plant growth and development. Together, these results suggest that the proper organization of cortical MTs is essential for the normal synthesis of plant cell walls. (Managing editor: Wei Wang) [source] Novel polymer electrolytes prepared by copolymerization of ionic liquid monomersPOLYMERS FOR ADVANCED TECHNOLOGIES, Issue 8 2002Masahiro Yoshizawa Abstract Ionic liquid monomer couples were prepared by the neutralization of 1-vinylimidazole with vinylsulfonic acid or 3-sulfopropyl acrylate. These ionic liquid monomer couples were viscous liquid at room temperature and showed low glass transition temperature (Tg) at ,83,°C and ,73,°C, respectively. These monomer couples were copolymerized to prepare ion conductive polymer matrix. Thus prepared ionic liquid copolymers had no carrier ions, and they showed very low ionic conductivity of below 10,9 S,cm,1. Equimolar amount of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) to imidazolium salt unit was then added to generate carrier ions in the ionic liquid copolymers. Poly(vinylimidazolium-co-vinylsulfonate) containing equimolar LiTFSI showed the ionic conductivity of 4,×,10,8 S,cm,1 at 30,°C. Advanced copolymer, poly(vinylimidazolium-co-3-sulfopropyl acrylate) which has flexible spacer between the anionic charge and polymer main chain, showed the ionic conductivity of about 10,6 S,cm,1 at 30,°C, which is 100 times higher than that of copolymer without spacer. Even an excess amount of LiTFSI was added, the ionic conductivity of the copolymer kept this conductivity. This tendency is completely different from the typical polyether systems. Copyright © 2002 John Wiley & Sons, Ltd. [source] Pd0 -Mediated Rapid Coupling between Methyl Iodide and Heteroarylstannanes: An Efficient and General Method for the Incorporation of a Positron-Emitting 11C Radionuclide into Heteroaromatic Frameworks,CHEMISTRY - A EUROPEAN JOURNAL, Issue 45 2009Masaaki Suzuki Prof. Abstract The Pd0 -mediated rapid trapping of methyl iodide with an excess amount of a heteroaryl-substituted tributylstannane has been investigated with the aim of incorporating a short-lived 11C-labelled methyl group into the heteroaromatic carbon frameworks of important organic compounds, such as drugs with various heteroaromatic structures, in order to execute a positron emission tomography (PET) study of vital systems. The reaction was first performed by using our previously developed CH3I/stannane/[Pd2(dba)3]/P(o -CH3C6H4)3/CuCl/K2CO3 (1:40:0.5:2:2:2) system in DMF at 60,°C for 5,min (conditions A), however, the reaction gave low yields for various heteroaromatic compounds. Increasing the amount of phosphine ligand (conditions B) led to a significant improvement in the yield, but the conditions were still not suitable for a range of basic heteroaromatic structures. Use of the CuBr/CsF system (conditions C) also provided a result similar to that obtained under conditions B with an increased amount of the phosphine. Thus, pyridine and related heteroaromatic compounds remained less reactive substrates. The problem was overcome by replacing the DMF solvent with N -methyl-2-pyrolidinone (NMP). The reaction in NMP at 60,100,°C for 5,min using a CH3I/stannane/[Pd2(dba)3]/P(o -CH3C6H4)3/CuBr/CsF (1:40:0.5:16:2:5) combination (conditions D) gave the methylated products in yields of more than 80,% (based on the reaction of CH3I) for all of the heteroaromatic compounds listed in this study. Thus, the combined use of NMP and an increased amount of phosphine is important for promoting the reaction efficiently. The use of this general approach to rapid methylation has been well demonstrated by the synthesis of the PET tracers 2- and 3-[11C]methylpyridines by using [Pd2(dba)3]/P(o -CH3C6H4)3/CuBr/CsF (1:16:2:5) in NMP at 60,°C for 5,min, which gives the desired products in HPLC analytical yields of 88 and 91,%, respectively. [source] Identification of the motilin cells in duodenal epithelium of premature infantsPEDIATRICS INTERNATIONAL, Issue 3 2005Toshiya Nishikubo AbstractBackground:,The aim of the present study was to examine the presence of motilin in the duodenal epithelial cells of premature infants of <32 weeks gestation. Methods:,Specimens from 10 deceased infants (gestational age: 26.4 ± 2.7 weeks and birthweight: 808 ± 303 g) were examined as subjects. All infants died of severe cardiopulmonary disorder or intraventricular hemorrhage (grade IV). The average survival period was 3.1 ± 1.9 days. Autopsies were performed and formalin-fixed duodenums were immunostained with rabbit antiserum to motilin by the labeled streptavidin,biotin (LSAB) method. An adult duodenum obtained by pancreatoduodenectomy was also examined for the presence of motilin as a positive control specimen. An absorption test using motilin peptide was performed to prove the specificity of the binding with rabbit antiserum to motilin. Results:,Motilin-containing cells were detected in the adult specimen, and the binding by rabbit antiserum to motilin was completely inhibited by excess amounts of motilin peptide, indicating that this binding was specific to motilin. All 10 infants had presence of motilin antigen in the epithelial cells of their duodenums. Conclusion:,This preliminary study indicates that the immunohistological analysis is specific to detect motilin-containing cells, and certifies the presence of motilin in duodenal epithelial cells of premature infants of <32 weeks gestation, including one at only 22 weeks gestation. [source] The regulation and function of phosphate in the human bodyBIOFACTORS, Issue 1-4 2004Eiji Takeda Abstract Inorganic phosphate (Pi) is required for cellular function and skeletal mineralization. Serum Pi level is maintained within a narrow range through a complex interplay between intestinal absorption, exchange with intracellular and bone storage pools, and renal tubular reabsorption. Pi is abundant in the diet, and intestinal absorption of Pi is efficient and minimally regulated. The kidney is a major regulator of Pi homeostasis and can increase or decrease its Pi reabsorptive capacity to accommodate Pi need. The crucial regulated step in Pi homeostasis is the transport of Pi across the renal proximal tubule. Type II sodium-dependent phosphate (Na/Pi) cotransporter (NPT2) is the major molecule in the renal proximal tubule and is regulated by hormones and nonhormonal factors. Recent studies of inherited and acquired hypophosphatemia which exhibit similar biochemical and clinical features, have led to the identification of novel genes, phosphate regulating gene with homologies to endopeptidases on the X chromosome (PHEX) and fibroblast growth factor-23 (FGF-23), that play a role in the regulation of Pi homeostasis. The PHEX gene encodes an endopeptidase, predominantly expressed in bone and teeth but not in kidney. FGF-23 may be a substrate of this endopeptidase and inhibit renal Pi reabsorption. In a survey in the United States and in Japan, the amount of phosphorus from food is gradually increasing. It is thought that excess amounts of phosphorus intake for long periods are a strong factor in bone impairment and ageing. The restriction of phosphorus intake seems to be important under low calcium intake to keep QOL on high level. [source] Modulation of the Aerobic Oxidative Polymerization in Phenylazomethine Dendrimers Assembling Copper ComplexesCHEMISTRY - A EUROPEAN JOURNAL, Issue 36 2010Dr. Takane Imaoka Abstract The aerobic oxidative polymerization of phenol derivatives can provide poly(phenylene oxide)s, which are known as engineering plastics. This oxidation can be carried out with atmospheric oxygen molecules as the oxidizing reagent in the presence of copper complexes as the catalyst; however, stoichiometric or excess amounts of bases are also generally required. By using a phenylazomethine dendrimer complexed with several equivalent amounts of copper chloride, the additive (base)-free polymerization of 2,6-difluorophenol was successful with a very small amount of the catalyst (0.7,mol,% of copper for the monomer) because the dendrimer was composed of many Schiff base units, affording a base and catalyst (copper complex) condensed reaction field. The resulting polymer was nearly linear and the molecular weight was very high. When the equimolar amount of the copper complex in one dendrimer molecule was increased, the polymer obtained under this reaction condition was rather branched, resulting in a higher glass transition temperature. [source] The "Borrowing Hydrogen Strategy" by Supported Ruthenium Hydroxide Catalysts: Synthetic Scope of Symmetrically and Unsymmetrically Substituted AminesCHEMISTRY - A EUROPEAN JOURNAL, Issue 24 2010Kazuya Yamaguchi Dr. Abstract The N -alkylation of ammonia (or its surrogates, such as urea, NH4HCO3, and (NH4)2CO3) and amines with alcohols, including primary and secondary alcohols, was efficiently promoted under anaerobic conditions by the easily prepared and inexpensive supported ruthenium hydroxide catalyst Ru(OH)x/TiO2. Various types of symmetrically and unsymmetrically substituted "tertiary" amines could be synthesized by the N -alkylation of ammonia (or its surrogates) and amines with "primary" alcohols. On the other hand, the N -alkylation of ammonia surrogates (i.e., urea and NH4HCO3) with "secondary" alcohols selectively produced the corresponding symmetrically substituted "secondary" amines, even in the presence of excess amounts of alcohols, which is likely due to the steric hindrance of the secondary alcohols and/or secondary amines produced. Under aerobic conditions, nitriles could be synthesized directly from alcohols and ammonia surrogates. The observed catalysis for the present N -alkylation reactions was intrinsically heterogeneous, and the retrieved catalyst could be reused without any significant loss of catalytic performance. The present catalytic transformation would proceed through consecutive N -alkylation reactions, in which alcohols act as alkylating reagents. On the basis of deuterium-labeling experiments, the formation of the ruthenium dihydride species is suggested during the N -alkylation reactions. [source] | |||||||||||||