Metabolic profiling of normal and hypertensive rat kidney tissues by hrMAS-NMR spectroscopy

Intact kidney tissue samples of normal and spontaneously hypertensive rats (SHRs) were analyzed by hrMAS-NMR spectroscopy and principal component analysis (PCA). Radial components (cortex, outer stripe of the outer medulla, inner stripe of the outer medulla, and papilla) were sampled from various regions across the kidney from multiple animals in order to establish inter- and intra-animal variability. The effects of temperature were also measured. Papilla was differentiated from the other tissue types, and this variation by tissue type was greater than the effect of temperature on the samples (spectra were compared from samples at 2 and 30 °C). This study also revealed long term stability issues of tissue storage at -80 °C. The PCA showed that the greatest differentiation between normal rats and SHRs was found in the cortex and the regions in the NMR spectra that were correlated with this variation were identified.Abbreviations hrMAS High-resolution magic angle spinning - NMR Nuclear magnetic resonance - PCA Principal component analysis - CSA Chemical shift anisotropy - DD Dipolar coupling - SHR Spontaneously hypertensive rat     

Determination of subnanomolar concentrations of cobalt by adsorptive stripping voltammetry at a bismuth film electrode

Procedures for trace cobalt determinations by adsorptive stripping voltammetry at in situ and ex situ plated bismuth film electrodes are presented. These exploit the enhancement of the cobalt peak obtained by using the Co(II)–dimethylglyoxime–cetyltrimethylammonium bromide–piperazine-N,N-bis(2-ethanesulfonic acid) system. The calibration graph for an accumulation time of 120 s was linear from 2 × 10^–10 to 2 × 10^–8 mol L^–1. The relative standard deviation from five determinations of cobalt at a concentration of 5 × 10^–9 mol L^–1 was 5.2%. The detection limit for an accumulation time of 300 s was 1.8 × 10^–11 mol L^–1. The proposed procedure was applied to cobalt determination in certified reference materials and in tap and river water samples.     

Fluorescence spectroscopy for monitoring deterioration of extra virgin olive oil during heating

The potential of fluorescence spectroscopy for characterizing the deterioration of extra virgin olive oil (EVOO) during heating was investigated. Two commercial EVOO were analysed by HPLC to determine changes in EVOO vitamin E and polyphenols as a result of heating at 170°C for 3 h. This thermal oxidation of EVOO caused an exponential decrease in hydroxytyrosol and vitamin E (R²=0.90 and 0.93, respectively) whereas the tyrosol content was relatively stable. At the same time, amounts of preformed hydroperoxides (ROOH), analysed by an indirect colorimetric method, decreased exponentially during the heating process (R²=0.94), as a result of their degradation into secondary peroxidation products. Fluorescence excitation spectra with emission at 330 and 450 nm were recorded to monitor polyphenols and vitamin E evolution and ROOH degradation, respectively. Partial least-squares calibration models were built to predict these indicators of EVOO quality from oil fluorescence spectra. A global approach was then proposed to monitor the heat charge from the overall fluorescence fingerprint. Different data pretreatment methods were tested. This study indicates that fluorescence spectroscopy is a promising, rapid, and cost-effective approach for evaluating the quality of heat-treated EVOO, and is an alternative to time-consuming conventional analyses. In future work, calibration models will be developed using a wide range of EVOO samples.     

Comparison of different sample preparation treatments for the analysis of wine phenolic compounds in human plasma by reversed phase high-performance liquid chromatography

Phenolic compounds are common constituents of wine. Due to their healthy properties the analysis in human fluids is interesting within bioavailability evaluation. They have been reported not to be stable in human plasma, particularly at room temperature. Most sample treatments have been reported for a single compound. Our aim in this paper is to study sample handling control conditions and improve phenolic stability in human plasma samples. We tested various sample treatments to determine whether they could be used for analysing a set of phenolic compounds usually present in wines.The compounds studied were six phenolic acids, five flavonoids, trans-resveratrol and tyrosol. The effect of the following factors was explored: temperature, pH, the addition of antioxidants and the addition of anticoagulants.The results suggest that the plasma samples should be kept at temperatures below −20 °C before analysis and that 1% ascorbic acid plus 10 μl/ml o-phosphoric acid should be added. Anticoagulants (heparin or EDTA) do not play a significant role in the stability of polyphenolic compounds.The recovery values of a number of sample treatments (solid phase extraction, extraction with methanol, deproteinization, inhibition of enzymatic plasma activity) were compared. The recovery values for most phenolic compounds were better if the enzymatic plasma activity was inhibited and acidified ethanol was used for deproteinization.     

A novel route to nanosized molybdenum boride and carbide and/or metallic molybdenum by thermo-synthesis method from MoO3, KBH4, and CCl4

Nanosized molybdenum boride and carbide were synthesized from MoO₃, KBH₄, and CCl₄ by thermo-synthesis method at lower temperature. The relative content of Mo, Mo₂C, and molybdenum boride in the product was decided by the molar ratio between MoO₃, KBH₄, and CCl₄. Increasing the molar ratio of CCl₄ to MoO₃ was favorable to the production of Mo₂C. Increasing the molar ratio of KBH₄ to MoO₃ was favorable to the production of molybdenum boride. By carefully adjusting the reaction conditions and annealing in Ar at 900°C, a single phase of MoB could be obtained.     

端视ICP－AES系统分析性能研究──Ⅰ．在稀土分析中的应用

本工作通过比较端视与侧视ＩＣＰ的分析性能，研究了端视ＩＣＰ系统对稀土元素的分析特性。高频发生器输出功率与载气流量对端视与侧视ＩＣＰ激发特性的影响没有明显差异，取光方式的不同是二者分析性能差异的根本原因。端视ＩＣＰ由于取光时避开了产生连续背景的环形热区和截取了整个中心通道的光谱，其背景减小，谱线强度增强，获得较好的测定下限。对１４种稀土元素测定下限的比较表明：端视ＩＣＰ比铡视ＩＣＰ下降１０－３０倍。     

On the Proper Normalization Constraint

In the variational optimization of a trial function the proper functional to be varied is the Rayleigh quotient with the normalization constraint explicitly imposed. It will be shown that only under certain very rigorous conditions can one use the energy functional to replace the Rayleigh quotient and that, therefore, the normalization constraint is by no means a matter of no consequence.     

Simultaneous determination of hydride (Se) and non-hydride-forming (Ca,Mg, K,P, S and Zn) elements in various beverages (beer,coffee, and milk), with minimum sample preparation,by ICP–AES and use of a dual-mode sample-introduction system

A method has been developed enabling direct analysis (i.e. after dilution only) of beer, instant coffee, milk, and milk powder by ICP–AES. Analysis of the beverages after dilution with a low concentration of HNO₃ was used for accurate determination of essential minor and trace elements (Ca, Mg, K, P, S, and Zn). Selenium, introduced as the hydride, was determined simultaneously with the other non-hydride-forming elements using the commercial multi-mode sample-introduction system (MSIS). To obtain accurate results, however, some simple pre-treatment was needed. Analysis was also performed after microwave-assisted decomposition of the samples. Three different modes of sample-preparation, i.e. dilution only, partial decomposition (aqua regia treatment), and complete decomposition were compared. The results obtained by use of the three different sample-preparation methods were in very good agreement. Results from analysis of certified reference material (SRM 1459 non-fat milk powder) also verified the accuracy of the methods. The limit of detection obtained for Se using dual-mode sample introduction was 0.5 ng mL^–1, which corresponds to approximately 2 ng g^–1 in beer and approximately 4 ng g^–1 in coffee and milk when using the recommended procedure.     

DABCO-catalyzed reaction of alpha-halo carbonyl compounds with dimethyl acetylenedicarboxylate: a novel method for the preparation of polysubstituted furans and highly functionalized 2H-pyrans

[Chemical reaction: see text] Polysubstituted furans and highly functionalized 2H-pyrans were prepared in good yields by DABCO-catalyzed reactions of alpha-halo carbonyl compounds with dimethyl acetylenedicarboxylate (DMAD) at room temperature.     

Correlated intermolecular interaction components from asymptotically corrected Kohn-Sham orbitals

In these years there was considerable interest inunderstanding of intermolecular forces in energetic(explosive) systems[1—3]. The supermolecular approach(SM) is widely adopted for calculating ab initio in-termolecular interactions. Nevertheless, it is unable toprovide physically meaningful interaction contribu-tions such as electrostatic, induction, repulsion anddispersion energies. In contrast, the symmetry-adaptedperturbation theory (SAPT)[4—8] has the ability to de-rive these correlated…