Inclusion complexes of spin-labeled indoles with cyclodextrins in aqueous solutions

Guest-host complexes of β- and γ-cyclodextrins (CDs) with two spin-labeled indole derivatives having the same molecular weights but different structures were studied by EPR spectroscopy in aqueous solutions and semiempirical quantum-chemical calculations of these systems were carried out. In the presence of CD the polarity of the NO group environment decreases and the rotational correlation time (τ) of guest molecules increases. Both indole derivatives form 1 : 1 complexes with γ-CD, the binding constants of the complexes being different more than twice. Simulation of EPR spectra made it possible to determine the indole ring orientation relative to the plane of the host molecule (at angles in the range 30–60°) and the rotational diffusion coefficients of the complexes, which corresponded to the hydrodynamic volume of one γ-CD molecule. In contrast to the complexes with γ-CD the rotational correlation times, τ, of the complexes with β-CD correspond to a hydrodynamic volume which much exceeds the volume of a single β-CD molecule. The complexes with β-CD are also characterized by more hydrophobic environment for guest molecules and absence of spin exchange with Ni²⁺ ions in the aqueous solution. There results are consistent with a dimeric structure of β-CD in the complex and with the orientation of the long axis of the guest molecule along the dimer axis. The energies and geometric parameters were calculated for all complexes by the PM3 method with a conventional set of parameters. The optimized energetically stable structures of the 1 : 1 complexes with γ-CD and of the 1 : 2 complexes with β-CD are consistent with experimental data. __________ Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 1139–1147, May, 2005.     

Langmuir probe measurements of axial variation of plasma parameters in 27.1 MHz rf oxygen planar discharges

Langmuir probe studies have been performed on rf (27.1 MHz) discharges in O₂ under planar reactor conditions to determine the axial variation of the plasma parameters (positive ion density, electron temperature, and dc space potential) as a function of pressure (20–220 Pa) and power (10–150 W) or current (0.1–2 A). By monitoring the second derivative of the I–V probe characteristics, the suppression of the rf component in the probe circuit can be optimized. Referring to this problem, numerical studies provide relations for the determination of the residual rf component as well as of the dc component of the plasma potential at incomplete rf compensation. The positive ion density is obtained from the ion saturation currents. Here the effect of collisions between ions and neutral particles within the probe sheath (for p> 100 Pa) is considered. The electron energy distribution function is found to be of the Maxwellian type for all discharge conditions investigated here. If the pressure and the power exceed critical values, the axial charge carrier distribution is characterized by a valley formation in the bulk plasma center. This fact demonstrates that secondary electron emission due to ion impact on the electrode surfaces and following ionization by these electrons near the sheaths in front of the electrodes are significant processes for sustaining the discharge. At low pressures (p60 Pa) the dc plasma potential was found to be identical with the half-peak maintaining voltage of the discharge, in agreement with the model idea of a symmetric rf planar discharge where the rf voltage drop across the bulk plasma can be neglected. For growing pressure, however, the plasma system moves gradually toward a situation where the V-I characteristics of the discharge are significantly controlled by processes in the bulk plasma. This transition depends on the current density.     

Synthesis of short and long-wavelength functionalised probes: amino acids' labelling and photophysical studies

Fluorescent labelling of α-amino acids at their N or C terminals in the main and lateral chains at short and long wavelengths was carried out in different ways. The N-[3-(naphthalen-1-ylamino)propanoyl]amino acid methyl esters synthesised showed strong fluorescence in the visible region (∼415 nm) of the electromagnetic spectrum. Condensation of these compounds with 5-diethylamino-2-nitrosophenol or 5-ethylamino-4-methyl-2-nitrosophenol produced the benzo[a]phenoxazine derivatives, with maximum emission wavelengths shifted to values higher than 644 nm. The synthesis of novel functionalised 5,9-diaminobenzo[a]phenoxazinium salts, by reaction of 5-ethylamino-4-methyl-2-nitrosophenol and N-substituted 1-naphthylamine and their use in the covalent labelling of the N or C terminals of valine, produced derivatives with long-wavelength emissions (644-653 nm). Photophysical studies using the synthesised compounds both in different solvents and in controlled pH were undertaken. Preliminary evaluation of photostability of the cationic polycyclic heterocycles in ethanol and water at physiological pH was also performed.     

配位聚合物[HgI2(btx)]n的制备、晶体结构及性能研究(btx=对二(1，2，4-三氮唑基甲基)苯)

A novel one-dimension coordination polymer [HgI₂(btx)]_n was synthesized through the reaction of alpha, alpha’-dichloro-p-xylene and HgI₂ in mixed MeOH-THF (1∶1) solution. The compound was characterized by X-ray crystallography and crystallizes in orthorhombic with space group Pnma. The cell parameters of the title compound are: a=0.936 3(2) nm, b=1.769 4(4) nm, c=1.032 2(2) nm, α=90°. Attractive I…I interactions link HgI₂(btx) chains directly resulting in the formation of three-dimensional network structure. In addition, the compound shows better luminescence spectroscopic property in the solid state, and is thermally stable below 126 ℃. CCDC: 233053.     

Shell-model calculation of51V using pairing-plus-surface-tensor-interaction

Employing⁴⁸Ca as the core, the structure of⁵¹V is studied in the framework of a conventional shell-model. A pairing-plus-surface-tensor-interaction is used as the effective two-body interaction. Besides all configurations arising from 1f _7/2 and 2p _3/2 single-particle orbits, configurations of the form wheren ₁+n ₂=3 (the number of extracore protons) andn ₂ = 1, 2 are also considered. Low-lying energy levels are calculated and a satisfactory agreement with the experimental values is obtained. Our calculated density of states is higher than that reported previously. We also present theB(E2) values for transitions between low-lying levels and the spectroscopic factors for the⁵⁰Ti (³He, d)⁵¹V reaction. The dependence of the interaction parameters on the mass number of the core nucleus is also studied.     

基于CVD方法生长在硅基底上立方碳化硅的拉曼散射研究（英文）

立方碳化硅(3C-SiC)薄膜通过化学气相沉积(CVD)制备在Si(100)衬底上。本论文主要通过椭偏光谱仪(SE)和拉曼散射仪对3C-SiC薄膜的微观结构和光学性能进行进一步的研究。根据SE的分析获得3CSiC薄膜厚度;根据拉曼散射的分析:可从TO模式和LO模式的线形形状的拟合得到样品的相关长度和载流子浓度。结果表明:该碳化硅(3C-SiC)薄膜质量随膜厚度增加而得到提高,同时分析了外延层厚度对薄膜特性的影响。     

Detection of LacZ‐Positive Cells in Living Tissue with Single‐Cell Resolution

The LacZ gene, which encodes Escherichia coli β‐galactosidase, is widely used as a marker for cells with targeted gene expression or disruption. However, it has been difficult to detect lacZ‐positive cells in living organisms or tissues at single‐cell resolution, limiting the utility of existing lacZ reporters. Herein we present a newly developed fluorogenic β‐galactosidase substrate suitable for labeling live cells in culture, as well as in living tissues. This precisely functionalized fluorescent probe exhibited dramatic activation of fluorescence upon reaction with the enzyme, remained inside cells by anchoring itself to intracellular proteins, and provided single‐cell resolution. Neurons labeled with this probe preserved spontaneous firing, which was enhanced by application of ligands of receptors expressed in the cells, suggesting that this probe would be applicable to investigate functions of targeted cells in living tissues and organisms.     

DNA‐Based Nanopore Sensing

Nanopore sensing is an attractive, label‐free approach that can measure single molecules. Although initially proposed for rapid and low‐cost DNA sequencing, nanopore sensors have been successfully employed in the detection of a wide variety of substrates. Early successes were mostly achieved based on two main strategies by 1) creating sensing elements inside the nanopore through protein mutation and chemical modification or 2) using molecular adapters to enhance analyte recognition. Over the past five years, DNA molecules started to be used as probes for sensing rather than substrates for sequencing. In this Minireview, we highlight the recent research efforts of nanopore sensing based on DNA‐mediated characteristic current events. As nanopore sensing is becoming increasingly important in biochemical and biophysical studies, DNA‐based sensing may find wider applications in investigating DNA‐involving biological processes.     

An Integrated Chemical Cytometry Method: Shining a Light on Akt Activity in Single Cells

Tools to evaluate oncogenic kinase activity in small clinical samples have the power to guide precision medicine in oncology. Existing platforms have demonstrated impressive insights into the activity of protein kinases, but these technologies are unsuitable for the study of kinase behavior in large numbers of primary human cells. To address these limitations, we developed an integrated analysis system that utilizes a light‐programmable, cell‐permeable reporter deliverable simultaneously to many cells. The reporter's ability to act as a substrate for Akt, a key oncogenic kinase, was masked by a 2‐4,5‐dimethoxy 2‐nitrobenzyl (DMNB) moiety. Upon exposure to ultraviolet light and release of the masking moiety, the substrate sequence enabled programmable reaction times within the cell cytoplasm. When coupled to automated single‐cell capillary electrophoresis, statistically significant numbers of primary human cells were readily evaluated for Akt activity.     

Investigation of structure interaction to nutrient properties and utilization in co-products after pellet processing at various conditions using advanced molecular spectroscopy

The molecular infrared (micro)spectroscopy, developed as a rapid, non-destructive and non-invasive analytical technique, is able to reveal structure features at a molecular level and provide tissue structure and chemistry information simultaneously. However, to date, this analytical technique is seldomly used in study processing induced structure change in relation to nutrient properties, utilization, and delivery in livestock. The objective of this article was to review the inter-relationship between molecular structures with nutritive properties and nutrient delivery in co-products from bioenergy production after pelleted processing using vibrational molecular spectroscopy. First, this article reviews recent progress in pelleting process research, related to physical quality of pellets, utilization for animals, processing quality, and current nutrition evaluation methodologies for pelleting. The emphasis of this study focused on the effect of conditioning temperature and time of the pellet processing on molecular structure changes and nutrient properties and nutrient delivery. The methods for nutritive properties and nutrient delivery were reviewed, which included various in vitro, in situ, in vivo, and nutrient modeling techniques. The molecular spectroscopic techniques included globar-sourced and synchrotron-sourced molecular spectroscopic techniques. The molecular spectra analysis included univariate and multivariate molecular spectral analyses. The relationship between molecular structural changes and truly absorbed nutrient supply was quantified. The research provides an insight how inherent structure changes induced by pellet processing on a molecular basis affected nutrient properties, utilization, and availability.