Sensitive Determination of DNA by Resonance Light Scattering with Pentamethoxyl Red

A novel sensitive method for the determination of nucleic acid (DNA) using the resonance light scattering (RLS) spectra of pentamethoxyl red has been developed. It is based on the effects on the resonance light scattering of Pentamethoxyl Red. The effective factors and the optimum conditions were studied, and the enhanced intensity of RLS is in proportion to the concentration of nucleic acids in the range of 0–2.54 µg mL⁻¹ for ct-DNA, 0–4.54 µg mL⁻¹ for hs-DNA. The limits of detection are 1.1 and 2.1 ng mL⁻¹, respectively. Most foreign substances do not interfere in the determination, and the method has good selectivity and high sensitivity. It has been applied to the determination of DNA in synthetic samples and in real samples with satisfactory results.     

Ni2（OEt）2／SiO2催化二氧化碳与丙烯直接合成甲基丙烯酸的研究

 采用表面改性法制备了负载型Ni2（OEt）2／SiO2双核金属乙氧基配合物催化剂，利用示差量热、红外光谱和微反技术对催化剂的表面结构、热稳定性、化学吸附性质和催化活性进行了研究．结果表明，负载型双核金属乙氧基配合物Ni2（OEt）2／SiO2中的Ni2＋与载体SiO2表面的O2－以双齿配位形式键合；二氧化碳在催化剂表面存在桥式吸附态和碳酸单乙酯基物种两种吸附态，丙烯则只有一种分子吸附态；在适宜的反应条件下，二氧化碳和丙烯在Ni2（OEt）2／SiO2催化剂上的反应产物主要是甲基丙烯酸．根据实验结果，提出了二氧化碳和丙烯在Ni2（OEt）2／SiO2催化剂表面的反应机理，反应物分子共吸附于催化剂表面同一活性单元上，羧酸根和丙烯解离吸附态的形成是反应顺利进行的关键步骤．     

Determination of gamma-hydroxybutyric acid in human urine by capillary electrophoresis with indirect UV detection and confirmation with electrospray ionization ion-trap mass spectrometry

γ-Hydroxybutyric acid (GHB), a minor metabolite or precursor of γ-aminobutyric acid (GABA), acts as a neurotransmitter/neuromodulator via binding to GABA receptors and to specific presynaptic GHB receptors. Based upon the stimulatory effects, GHB is widely abused. Thus, there is great interest in monitoring GHB in body fluids and tissues. We have developed an assay for urinary GHB that is based upon liquid–liquid extraction and capillary zone electrophoresis (CZE) with indirect UV absorption detection. The background electrolyte is composed of 4 mM nicotinic acid (compound for indirect detection), 3 mM spermine (reversal of electroosmosis) and histidine (added to reach a pH of 6.2). Having a 50 μm I.D. capillary of 40 cm effective length, 1-octanesulfonic acid as internal standard, solute detection at 214 nm and a diluted urine with a conductivity of 2.4 mS/cm, GHB concentrations ≥2 μg/ml can be detected. Limit of detection (LOD) and limit of quantitation (LOQ) were determined to be dependent on urine concentration and varied between 2–24 and 5–60 μg/ml, respectively. Data obtained suggest that LOD and LOQ (both in μg/ml) can be estimated with the relationships 0.83 κ and 2.1 κ, respectively, where κ is the conductivity of the urine in mS/cm. The assay was successfully applied to urines collected after administration of 25 mg sodium GHB/kg body mass. Negative electrospray ionization ion-trap tandem mass spectrometry was used to confirm the presence of GHB in the urinary extract via selected reaction monitoring of the m/z 103.1→m/z 85.1 precursor–product ion transition. Independent of urine concentration, this approach meets the urinary cut-off level of 10 μg/ml that is required for recognition of the presence of exogenous GHB. Furthermore, data obtained with injection of plain or diluted urine indicate that CZE could be used to rapidly recognize GHB amounts (in μg/ml) that are ≥ 4 κ.     

激光参数对甲醇激光表面反应性能的影响规律

以Ｓｉｏ２和ＰＭｏ１２为表面材料，用可选频脉冲ＴＥＡ－ＣＯ２激光器作光源，考察了激发频率、激光强度、脉冲次数和脉冲间隔等激光参数对甲醇激光分解反应性能的影响规律。结果表明：甲醇的激光表面反应具有频率选择性，激发频率不同，甲醇分解率也不同；不同表面上激发次数影响规律不同，随着激发次数增加，甲醇转化率增加；脉冲间隔的改变只影响转化率，脉冲间隔越小，能量利用率越高，甲醇分解率越高；激光强度的提高可增加甲     

丙烯酸β-羧乙酯-苯乙烯共聚合的研究

<正> 丙烯酸酯类聚合物是一类性能优良的橡胶、涂料和粘合剂,酯的结构不同可得到性能各异的均聚物和共聚物。 丙烯酸β-羧乙酯(APA)是一种具有多种反应功能的丙烯酸酯单体,结构式为:CH_2=CH—COOCH_2CH_2COOH,其双键可发生加成聚合,制得的大分子带有反应性酯基和羧基侧基,以其制备反应性大分子具有广泛的应用前景。我们研究了丙烯酸β-羧     

Copper corrosion in buffered and non-buffered synthetic seawater: a comparative study

The electrochemical behaviour of copper in neutral buffered and non-buffered synthetic seawater and in pure chloride solutions has been studied by cyclic voltammetry, weight loss measurements, open circuit potential and scanning electron microscopy (SEM). Values of the repassivation potentials of Cu in non-buffered and buffered synthetic seawater, at 50 mV s^–1, were 0.12 and 0.46 V vs. SCE, respectively. The sharpness, heights and location of the different peaks as well as their charges were shown to be influenced by the composition of the solution, buffering conditions, deoxygenation, polarization potential and time. High chloride concentrations lead to higher oxidation charges. The anodic and the cathodic charges were shown to increase as the chloride concentration increases. The open circuit potential transients of copper in non-deoxygenated, non-buffered synthetic seawater indicate pitting from the beginning of the exposure, while in buffered solutions the pitting appeared only after a quite long exposure period, i.e. after 40 days. Corrosion rates of Cu samples after 3 months of immersion were higher in solutions of pure chloride (0.5 M) than in synthetic seawater. After six months the differences were even more noticeable. SEM images have showed a somewhat higher density of pits on copper samples immersed in the chloride solution (0.5 M), in comparison with those in synthetic seawater.     

2-(4-氯苯基)-3-甲基丁酸的消旋

以酸酐及有机惰性溶剂作混合溶剂，少量叔胺等作催化剂，2-(4-氯苯基)-3-甲基丁酸能在比较温和的条件下基本完全消旋，收率接近90％。     

IR study of heterogeneity of OH groups in zeolite HY-splitting of OH and OD bands

We have been studying the problem of heterogeneity of OH groups in zeolites HY for a long time. The heterogeneity was suggested by the shift of the IR band of OH groups restoring upon ammonia desorption and also by the fact that the band of OH groups forming hydrogen bonds was relatively broad (broader than for homogeneous acidic OH). In the present study we present another important argument for heterogeneity: the splitting of the IR band of free OH and OD groups in a zeolite of Si/Al=8.3 dealuminated by (NH₄)₂SiF₆ treatment. Such a splitting is the best seen in low temperature spectra of OD groups. We found less acidic 3640 cm⁻¹ (AlO)(SiO)₂SiO₁HAl(OSi)₃ and more acidic 3625 cm⁻¹ (SiO)₃SiO₁HAl(OSi)₃ groups. The presence of these two kinds of hydroxyls corresponds to the presence of Si(2Al) and Si(1Al), respectively, detected in ²⁹Si MAS NMR spectra. We also found a small amount of strongly acidic 3599 cm⁻¹ hydroxyls interacting with extraframework Al species.     

Molecular recognition properties of salicylic acid-imprinted polymers

Summary Two molecularly imprinted polymers (MIP) have been prepared using the acidic drug salicylic acid, which can form intramolecular hydrogen bond, as the template and acrylamide or 4-vinylpyridine as the functional monomer. HPLC was used to evaluate the binding performance of the MIP for the template and for several analogues. The results showed that the MIP (P₂) prepared using acrylamide as the functional monomer had no molecular imprinting effect whereas that (P₁) prepared using 4-vinylpyridine as the functional monomer had a significant molecular imprinting effect. The reason the molecular imprinting effect was different for the two MIP was elucidated and the molecular recognition properties of P₁ were studied in detail. It was confirmed that electrostatic interaction played an important role in the molecular recognition of P₁. Scatchard analysis showed that two types of binding site with distinctly different affinity were formed in P₁. Their dissociation constants were estimated to be 7.6×10⁻⁵ mol L⁻¹ and 3.2×10⁻³ mol L⁻¹, respectively. Because P₁ has high affinity and selectivity for salicylic acid not only in organic systems but also in water-containing systems, it gives P₁ the potential for use in the enrichment, separation, and detection of salicylic acid in biological fluids.     

Progress on phthalocyanine-conjugated Ag and Au nanoparticles: Synthesis,characterization, and photo-physicochemical properties

Phthalocyanine (Pc) complexes are an important class of dyes with numerous (e.g., biological, photophysical, and analytical) applications. Among the methods used to improve the properties of these complexes, one should mention the introduction of different substituents, variation of the central metal ion, ligand exchange, and conjugation to nanomaterials (e.g., carbon-based nanomaterials and metal nanoparticles (NPs)). This work briefly reviews Pc complex conjugation to Ag and Au NPs, highlights the different NP shapes, and discusses the diversity of conjugation approaches. Moreover, the use of UV–Vis spectroscopy, powder X-ray diffraction, X-ray photoelectron spectroscopy, transmission electron microscopy, atomic force microscopy, dynamic light scattering and Fourier transform infrared spectroscopy to characterize Pc-NP hybrids is summarized. The effect of conjugation on Pc photo-physicochemical properties (fluorescence, singlet oxygen generation, triplet state formation, and optical limiting behavior) is discussed, and future perspectives for the synthesis and applications of new hybrids are provided.