Rapid determination of catecholamines in urine samples by nonaqueous microchip electrophoresis with LIF detection

A method was developed for the rapid separation of catecholamines by nonaqueous microchip electrophoresis (NAMCE) with LIF detection, A homemade pump‐free negative pressure sampling device was used for rapid bias‐free sampling in NAMCE, the injection time was 0.5 s and the electrophoresis separation conditions were optimized. Under the optimized conditions, the samples were separated completely in <1 min. The average migration times of the epinephrine (E), dopamine (DA), and norepinephrine (NE) were 34.26, 43.81, and 50.07 s, with an RSD of 1.05, 1.26, and 0.89% (n = 7), respectively. The linearity of the method ranged from 0.0125 to 2.0 mg/L for E and 0.025～4.0 mg/L for DA and NE, with correlation coefficients ranging between 0.9978 and 0.9986. The detection limits of E, DA, and NE were 2.5, 5.0, and 5.0 μg/L, respectively. The recoveries of E, DA, and NE in spiked urine samples were between 86 and 103%, with RSDs of 4.5～6.8% (n = 5). The proposed NAMCE with LIF detection combined with a pump‐free negative pressure sampling device is a simple, inexpensive, energy efficient, miniaturized system that can be successfully applied for the determination of catecholamines in urine samples.     

Transition‐Metal‐Catalyzed Oxidation of Metallic Sn in NiO/SnO2 Nanocomposite

It is well accepted that metallic tin as a discharge (reduction) product of SnO_x cannot be electrochemically oxidized below 3.00 V versus Li⁺/Li⁰ due to the high stability of Li₂O, though a similar oxidation can usually occur for a transition metal formed from the corresponding oxide. In this work, nanosized Ni₂SnO₄ and NiO/SnO₂ nanocomposite were synthesized by coprecipitation reactions and subsequent heat treatment. Owing to the catalytic effect of nanosized metallic nickel, metallic tin can be electrochemically oxidized to SnO₂ below 3.00 V. As a result, the reversible lithium‐storage capacities of the nanocomposite reach 970 mAh g^?1 or above, much higher than the theoretical capacity (ca. 750 mAh g^?1) of SnO₂, NiO, or their composites. These findings extend the well‐known electrochemical conversion reaction to non‐transition‐metal compounds and may have important applications, for example, in constructing high‐capacity electrode materials and efficient catalysts.     

氨基化镁铝类水滑石修饰电极及电化学杀菌

以层间插入十二烷基磺酸钠的镁铝类水滑石（Mg/Al-SDS-HTLc）,与十六烷基三甲基溴化铵（CTAB）和3-氨丙基三乙氧基硅烷（APS）缩合反应制备了氨基化镁铝类水滑石（Mg/Al-NH2-HTLc）。 然后以Mg/Al-NH2-HTLc修饰热解石墨电极,通过循环伏安法探讨了该电极对吸附在其表面的大肠杆菌的杀灭作用。 结果表明,被吸附的大肠杆菌在经过循环伏安扫描后死亡率达到98.68%,大肠杆菌的死亡可能是由于细胞膜中易氧化物质（如鸟嘌呤）被氧化所致。     

Simultaneous determination of trimethylamine,formaldehyde and benzene via the cataluminescence of In<Subscript>3</Subscript>LaTi<Subscript>2</Subscript>O<Subscript>10</Subscript> nanoparticles

The authors describe a cataluminescence (CTL) based sensing method via signals generated at the surface of In₃LaTi₂O₁₀ nanoparticles for simultaneous determination of trimethylamine, formaldehyde and benzene in air. The analytical wavelengths are 340 nm, 440 nm and 600 nm, and the best surface temperature of the catalytic material is 275 °C. The limits of detection of this method are 0.3 mg?m^?3 for trimethylamine, 0.07 mg?m^?3 for formaldehyde, and 0.2 mg?m^?3 for benzene. The linear ranges of CTL intensity versus gas/vapor concentration are from 1.0 to 65.1 mg?m^?3 for trimethylamine, from 0.2 to 72.5 mg?m^?3 for formaldehyde, and from 0.5 to 77.5 mg?m^?3 for benzene. The recoveries after testing 10 standard samples ranged from 98.1% to 102.6% for trimethylamine, from 98.1% to 102.6% for formaldehyde, and from 97.7% to 103.8% for benzene. Gaseous ammonia, acetaldehyde, toluene, ethylbenzene, ethanol, sulfur dioxide and carbon dioxide do not interfere. The relative deviation of the CTL signals after 200 h of continuous detection of trimethylamine, formaldehyde and benzene is <3%.

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Graphical abstract Schematic of a cataluminescence (CTL) based method for simultaneous determination of trimethylamine (TMA), formaldehyde (HCHO) and benzene (C₆H₆) in air. The linear ranges of CTL intensity versus gas/vapor concentration are from 1.0 to 65.1 mg?m^?3 for TMA, from 0.2 to 72.5 mg?m^?3 for HCHO, and from 0.5 to 77.5 mg?m^?3 for C₆H₆.

     

Two new sesquiterpenes derivatives from marine fungus Leptosphaerulina Chartarum sp. 3608

Two new sesquiterpenes, leptoterpenes A (1) and B (2) were isolated from the fungus Leptosphaerulina Chartarum sp. 3608, derived from a crinoid. It was the first chemical study on this species. The structures of these compounds were elucidated by spectroscopic methods including NMR and MS spectrometry. The absolute configurations of the new compounds were determined on the basis of the single-crystal X-ray diffraction and electronic circular dichroism data analysis. All compounds were tested for their anti-inflammatory activity and the inhibitory effects on Tyrosyl DNA phosphodiesterase II (TDP2).     

Synthesis and fungicidal activity of novel 3,5-diarylpyrazole derivatives

(E)-3-(2-chlorophenyl)-1-(2,4-dichlorophenyl) prop-2-en-1-one was prepared from 2-chlorobenzaldehyde followed by cyclization with hydrazine monohydrate. Eight new 3-(2,4-Di-chlorophenyl)-5-(2-chlorophenyl)-4,5-dihydro-N-acylpyrazole derivatives were synthesized and characterized by elemental analysis, IR and ¹H NMR spectroscopy. The experimental results show that the inhibition ratio of compounds 3f towards H. Oryzae and P. oryzae at 50 mg·L⁻¹ is 55.2% and 57.1%, respectively. The inhibition ratio of compounds 3g towards H. Oryzae, P. oryza, S. Sclerotiorum at 50 mg·L⁻¹ is 53.3%, 60.0%, 50.4% respectively. __________ Translated from Chinese Journal of Applied Chemistry, 2007, 27(7): 835–837     

Osmium Redox Hydrogel Mediated Biosensor for Measurement of Low Concentration Glucose Extracted by Reverse Iontophoresis

An osmium redox hydrogel mediated biosensor for continuous monitoring of glucose extracted from subcutaneous solution by reverse iontophoresis has been developed. For the measurement of low concentration glucose, osmium‐poly(vinylpyridine) wiring horseradish peroxidase was introduced to modify the smooth Au electrodes, and the developed glucose biosensor exhibited a high sensitivity of 11.45 nA μM^?1 cm^?2 and a low detection limit of 2 μM, as well as a high operational stability of more than 97% of its initial activity over a test period of 13.5 h in stirred glucose solution at low applied potential (?0.1 V vs. Ag|AgCl), efficiently inhibiting the electroactive interferences. Permeability of the hydrogels was studied and a diffusion coefficient of 2.4×10^?5 cm²/s for H₂O₂ was obtained. In addition, the effects, such as temperature and the variation happening on Ag|AgCl counter electrode, on determination of glucose were also considered. The proof‐of‐feasibility of the biosensors for the monitoring of the glucose extracted from the subcutaneous solution was tested in vitro, and the responses of the sensors were analyzed. A linear response to current produced by extracted glucose in the concentration range of subcutaneous glucose from 1.0 to 12 mM was obtained with a correlation coefficient up to 0.989. These results testify the feasibility of the developed sensors for measuring the low concentration glucose and have significance for the development of noninvasive glucose monitoring system for the control of diabetes.     

攀登科学最高峰的第三世界科学家——1970年诺贝尔化学奖得主卢伊斯·弗德里科·莱洛伊尔

阿根廷生物化学家卢伊斯·弗德里科·莱洛伊尔因发现糖核苷酸及其在碳水化合物生物合成中的作用而获1970年诺贝尔化学奖。莱洛伊尔一生不仅致力于科学研究,还积极推动阿根廷的大学和医学教育,建立了致力于科学研究的坎波马尔基金会。本文回顾了莱洛伊尔的科研成果、相关研究背景以及他的科研历程,分析了他能够获得成功的因素;讨论了名师对科研人员学术指导的重要作用、及时调节研究过程中产生的各类情绪的积极意义以及敢于大胆跨界探索对科研人员的重要性。     

DNA microarray synthesis by using PDMS molecular stamp (II)

Based on the standard phosphoramidites chemistry protocol, two oligonucleotides synthetic routes were studied by contact stamping reactants to a modified glass slide. Route A was a contact coupling reaction, in which a nucleoside monomer was transferred and coupled to reactive groups (OH) on a substrate by spreading the nucleoside activated with tetrazole on a polydimethylsiloxane (PDMS) stamp. Route B was a contact detritylation, in which one nucleoside was fixed on the desired synthesis regions where dimethoxytrityl (DMT) protecting groups on the 5’-hydroxyl of the support-bound nucleoside were removed by stamping trichloroacetic acid (TCA) distributed on features on a PDMS stamp. Experiments showed that the synthetic yield and the reaction speed of route A were higher than those of route B. It was shown that 20 mer oligonucleotide arrays immobilized on the glass slide were successfully synthesized using the PDMS stamps, and the coupling efficiency showed no difference between the PDMS stamping and the conventional synthesis methods.