Highly sensitive voltammetric biosensor for nitric oxide based on its high affinity with hemoglobin

Although heme protein-based, amperometric nitric oxide (NO) biosensors have been well documented in previous studies, most have been conducted in anaerobic conditions. Herein we report a novel hemoglobin-based NO biosensor that is not only very sensitive but also usable in air. The heme protein was entrapped in a sodium montmorillonite film, which was immobilized at a pyrolytic graphite electrode surface. Film-entrapped hemoglobin can directly exchange electrons with the electrode, and this process has proven to favor the catalytic reduction of oxygen. In addition, NO induced a cathodic potential shift of the catalytic reduction peak of oxygen. This potential shift was proportional to the logarithm of NO concentration ranging from 4.0 × 10⁻¹¹ to 5.0 × 10⁻⁶ mol/L. The detection limit has been estimated to be 20 pM, approximately four orders lower than previously reported amperometric detectors.     

Order-disorder effects of small guests in clathrates studied by nuclear quadrupole resonance and crystallography. Part I. Carbon tetrachloride and related molecules in Ni(SCN)2(3-methylpyridine)4

NQR spectroscopy and X-ray crystallography have been jointly applied to the study of the small guest molecules CH₂Cl₂, CHCl₃, CCl₄, CBr₂Cl₂, C(CH₃)2Cl₂ etc. in the Werner host complex Ni(SCN)₂(3-methylpyridine)₄. Specific host-guest dipole-dipole interactions play an important role in order-disorder effects for guest molecules in the cavities of orthorhombic system,Fddd. Thus a weakly polar molecule such as CBr₂Cl₂ exhibits a disordered alternation, both the bromine and the chlorine atoms occupying the two possible sites in theC ₂ cavity, whereas for the polar molecule C(CH₃)₂Cl₂, an ordered structure is observed. In addition, two new types of crystal structures,C2/c andP , are reported here for dichloromethane and chloroform clathrates.     

Hydrothermal synthesis and intercalation behavior of a layered titanium phosphate Ti2(H2PO4)(HPO4)(PO4)2 · 0.5C6N2H16, with an extended γ-phase intercalated into organic amine

With a hydrothermal technique, a layered titanium phosphate with the formula Ti₂(H₂PO₄)(HPO₄)(PO₄)₂ · 0.5C₆N₂H₁₆ (denoted TP-J2) has been prepared by treating the Ti/H₃PO₄/H₂O/1-methylpiperazine system directly. The as-synthesized products were characterized by powder X-ray diffraction, CP-MAS solid-state ³¹P NMR spectroscopy, thermogravimetric and differential thermal analyses (TG-DTA). The structure was solved by single-crystal X-ray diffraction analysis and it presents an extended γ-phase intercalated with organic amine. Crystal data: triclinic, , a = 8.106 (2) Å, b = 8.197 (2) Å, c = 11.658 (2) Å.  = 78.32 (3)°, β = 80.85 (3)°, γ = 77.90 (3)°, Z = 2. Additionally, the intercalation behavior of TP-J2 with n-alkyl monoamine (n = 2, 3, 4, 6, 8, 10 and 12) was investigated. Owing to the strong brønsted base, N,N′-dimethylpiperazine, resides in the interlayer, it presented unusual features of TP-J2 in contrast with that of γ-Tip.     

Synthesis of New Spiropyrans With a Polyaromatic or Heteroaromatic Pendant and Their Photochromic Bedhaviors

A series of spiropyrans with a polyaromatic or heteroaromatic pendant was synthesized conveniently.Their photochromic behaviors were investigated with the aid of absorption spectral measurements.The results indicated that the compounds with the same parent spiropyran but different aromatic pendant show significantly different photochromic properties.This may be due to the π-π orbital interaction between the polyaromatic pendant and the open photomerocyanine form of spiropyran.The results obtained are very useful in the molecule design area.     

On a class of least-element complementarity problems

The present paper studies the linear complementarity problem of finding vectorsx andy inR ₊ ⁿ such thatc + Dx + y 0,b – x 0 andx ^T (c + Dx + y) = y ^T (b – x) = 0 whereD is aZ-matrix andb > 0. Complementarity problems of this nature arise, for example, from the minimization of certain quadratic functions subject to upper and lower bounds on the variables. Two least-element characterizations of solutions to the above linear complementarity problem are established first. Next, a new and direct method to solve this class of problems, which depends on the idea of least-element solution is presented. Finally, applications and computational experience with its implementation are discussed.Research partially supported by the National Science Foundation Grant MCS 71-03341 A04 and the Air Force Office of Scientific Research Contract F 44620 14 C 0079.     

Construction of Binary Quantum Error-Correcting Codes from Orthogonal Array

By using difference schemes, orthogonal partitions and a replacement method, some new methods to construct pure quantum error-correcting codes are provided from orthogonal arrays. As an application of these methods, we construct several infinite series of quantum error-correcting codes including some optimal ones. Compared with the existing binary quantum codes, more new codes can be constructed, which have a lower number of terms (i.e., the number of computational basis states) for each of their basis states.     

磁性和超导性共存与转化的唯象理论

我们从分析磁性超导体的晶体结构和电子结构出发,运用平均分子场理论,求出了它的磁化率、比热、临界温度、磁转化温度和它的相图。分析了它们共存和转化的条件与特点。     

不同进风型式下气体冷却服中空气流动与换热的研究

根据气体冷却服的特点,对不同进风型式下气体冷却服中空气流动与换热进行研究。建立了进气口加设挡板层、进气口带均流器型和直吹型3种型式气体冷却服(服装夹层)中冷却空气流动过程的数学模型。对气体的流动过程进行分析,结果表明:不同的进风型式对气体冷却服空气层的温度分布状况、平均气流流速、平均温度、对流散热量影响较大;其中进气口加设挡板层的服装空气夹层温度分布最均匀,进气直吹型的平均气流流速最大,对流散热效果最好。研究结果为气体冷却服进一步的布风优化设计提供了理论和应用依据。     

光谱成像技术无损鉴别西洋参饮片的研究

应用电可控液晶光谱成像装置,测定不同市售来源的西洋参饮片,以期为其质量控制提供新的方法。系统光谱分辨率5nm,光谱覆盖范围为405～680nm,空间分辨率50lp·mm-1。从成像光谱立方体中提取特征光谱曲线,构建饮片指纹图谱;采用主成分等聚类分析方法解析其指纹图谱,用于饮片真伪鉴别与质量判定。结果与性状,显微及理化鉴定结果相吻合。表明光谱成像分析技术可用于中药指纹图谱的构建和质量评价,操作方法简便、快速、无损。