Hindered organoboron groups in organic synthesis. 17 [1]. Synthesis of 2,4,6-triisopropylphenylborane (TripBH2)2, a useful alternative to thexylborane

2,4,6-Triisopropylphenylborane (tripylborane, TripBH₂) resembles thexylborane in having a single, bulky organic group attached to boron, but the group is aromatic rather than aliphatic. The compound has been synthesized by two alternative routes, one involving direct reduction of dimethoxytripylborane and the other involving redistribution between ditripylborane and borane. It is a solid which is considerably more stable than thexylborane.     

Experimental study on the two-phase flow pattern and transformation characteristics of a flow mixing nozzle under a moderate flow rate

Meccanica - A flow mixing nozzle can produce satisfactory atomization for heavy oil. However, the study of the internal flow pattern of this nozzle, along with the spray morphology and its...     

Event-triggered output-feedback tracking of a class of nonlinear systems with unknown time delays

A single function approximation (SFA) approach for event-triggered output-feedback tracker design is presented for uncertain nonlinear time-delay systems in lower-triangular form. Contrary to the existing event-triggered output-feedback control methods dependent on multiple function approximators in the presence of lower-triangular nonlinearities, the proposed SFA approach provides the following advantages: (i) the simple observer structure independent of function approximators; (ii) one event-triggering condition based on only a tracking error; and (iii) the simple control scheme using one function approximator. Thus, the structural simplicity is allowed for implementing the observer and the event-triggering law in the sensor part and the adaptive tracker in the control part. Under the proposed SFA-based event-triggered control scheme, it is shown that the boundedness of closed-loop signals and the existence of a minimum inter-event time are guaranteed regardless of unknown time-delay nonlinearities and unmeasurable state variables.

     

Analysis of the Composition of Deinagkistrodon acutus Snake Venom Based on Proteomics,and Its Antithrombotic Activity and Toxicity Studies

There is a strong correlation between the composition of Deinagkistrodon acutus venom proteins and their potential pharmacological effects. The proteomic analysis revealed 103 proteins identified through label-free proteomics from 30 different snake venom families. Phospholipase A2 (30.0%), snaclec (21.0%), antithrombin (17.8%), thrombin (8.1%) and metalloproteinases (4.2%) were the most abundant proteins. The main toxicity of Deinagkistrodon acutus venom is hematotoxicity and neurotoxicity, and it acts on the lung. Deinagkistrodon acutus venom may have anticoagulant and antithrombotic effects. In summary, the protein profile and related toxicity and pharmacological activity of Deinagkistrodon acutus venom from southwest China were put forward for the first time. In addition, we revealed the relationship between the main toxicity, pharmacological effects, and the protein components of snake venom.     

An Improved Method for Purification of β-Copperphthalocyanine

A sublimation apparatus in which a high temperature slightly lower than the sublimation point of copperphthalocyanine remains constant over a long condensation region has been developed. A sufficiently pure material for electrophotographic measurements can be obtained only when this high temperature is maintained nearly constant over the long condensation region along the sublimation tube. After the thired sublimation, the value of copper contents in the sample is 11.03 · 0.02%, according to the chelatometric titrations, while the theoreitcal value of stoichimetric composition is 11.03%. Emission spectrochemical analysis shows that only traces of Si and Mg are found in the sample after the sixth sublimation. Single crystal srown in the sublimation tube are characterized and the growth mechanism is discussed.     

EPR studies on H-abstractions/spin-trapping reactions of new 'magic blue' reagents with alcohols

The H-abstractions/spin-trapping reactions with primary, secondary and tertiary alcohols of new 'magic blue' reagents, namely, the blue F113 (CClF₂CCl₂F) solution containing bis{perfluoro[1-(2-fluorosulfonyl)ethoxy]ethyl} nitroxide (2) and perfluoro[1-nitroso-1-(2-fluorosulfonyl)ethoxy]ethane (3) both generated in the reaction of perfluoro[2-(2-fluorosulfonyl)ethoxy]propionyl peroxide (1) with sodium nitrite in F113 at room temperature, were studied by EPR. Based on the interpretation of the EPR spectra of the spin adducts, nitroxides, the region-selectivity of H-abstraction has been disclosed and the possible mechanistic paths of H-abstraction have also been discussed. EPR of H-abstraction by using 'magic blue' reagents can also be used for producing various hydroxyalkyl radicals from common alcohols.     

Interaction of cellulase with sodium dodecyl sulfate at critical micelle concentration level

The interactions between Trichoderma reesei cellulase and an anionic surfactant, sodium dodecyl sulfate (SDS), at critical micelle concentration level have been investigated using isothermal titration calorimetry, fluorescence spectroscopy, and circular dichroism. SDS micelles have dual interactions with cellulase: electrostatic at first and then hydrophobic interactions. When the concentration of SDS is smaller than 45.0 mM, SDS micelles cause a partial loss in the hydrolytic activity together with a steep decrease in the -helical content of cellulase. With further increasing the concentration of SDS, however, a re-formation of the -helical structure and a partial recovery of the hydrolytic activity of cellulase induced by SDS micelles are observed. Taken together, these results indicate that SDS micelles exert dual effects on cellulase through binding as both a denaturant and a recovery reagent.     

基于纳米金探针和基因芯片的DNA检测新方法

运用荧光纳米金探针和基因芯片杂交建立一种新的DNA检测方法. 荧光纳米金探针表面标记有两种DNA探针: 一种为带有Cy5荧光分子的信号探针BP1, 起信号放大作用; 另一种为与靶DNA一部分互补的检测探针P532, 两种探针比例为5∶1. 当靶DNA存在时, 芯片上捕捉探针(与靶DNA的另一部分互补)通过碱基互补配对结合靶DNA, 将靶DNA固定于芯片上; 荧光纳米金探针通过检测探针与靶DNA及芯片结合, 在芯片上形成“三明治”复合结构, 最后通过检测信号探针上荧光分子的信号强度来确定靶DNA的量. 新方法检测灵敏度高, 可以检测浓度为1 pmol/L的靶DNA, 操作简单, 检测时间短. 通过改进纳米金探针的标记和优化杂交条件, 可进一步提高核酸检测的灵敏度, 这将在核酸检测方面具有重要的应用价值.     

Synthesis and Crystal Structure of a Novel Zinc Phosphonate Compound： [Zn（phen）（m-OOCC6H4PO3H）]

A novel zinc（H） metal phosphonate compound [Zn（phen）（m-OOCC6H4PO3H）] 1 （phen = phenanthroline） has been synthesized under hydrothermal conditions. Single-crystal X-ray structure analysis reveals that compound 1 belongs to the triclinic system, space group P1 with a = 9.3356（19）, b = 10.203（2）,c = 10.743（2）A,α = 76.3030（70）, β= 69.2317（51）, y = 84.3833（74）°,V = 929.4（3） ,A3, Z = 2, C2OH15N2O5PZn, Mr = 459.68, Dc = 1.643 g/cm^3,μ= 1.444, mm^-1, F（000） = 468, the final R = 0.0330 and wR = 0.0848. In the structure, the central ion Zn（H） is five-coordinated, linking three O atoms with one from carboxyl and the other two from phosphonyl group. The remained two coordinate sites were occupied by two N atoms from one phen molecule to form the asymmetric unit. Then every two adjacent asymmetric units are bridged by the O atoms from phosphonate group and carboxyl to give rise to a 1D chain along the b axis. These chains are constructed by weak π-π stacking interactions and C-H…π interactions to generate a 3D supramolecular framework.