High-energy complex copper(II) perchlorate with 1,5-pentamethylenetetrasole as ligand

Possibility of obtaining an energy-saturated metal complex, copper tetrakis[cyclopentamethylenetetrasol] perchlorate, was studied by reacting copper(II) perchlorate hexahydrate with cyclopentamethylenetetrazol. The composition and structure of the complex were confirmed by elemental analysis and UV, IR, ¹H NMR, and ESR spectroscopies. The thermal decomposition of the metal complex synthesized was analyzed and its explosive characteristics and combustion law, as well as the combustion law of a model formulation of a composite solid propellant with addition of the complex, were determined.     

Fundamentals, achievements, and perspectives for development of solid-flame combustion

The review is devoted to the problem of self-propagating high-temperature synthesis (SHS). The fundamentals of SHS are briefly considered, the most promising results of the experimental diagnostics and modeling of SHS processes are presented, new nonlinear phenomena and the data of thermodynamic calculations, as well as kinetic and macrokinetic studies are discussed. The main types of the SHS technology and their application for the preparation of new compounds, materials, and items along with technical and economical effectiveness are considered. New directions and perspectives of SHS are discussed. The review was prepared from materials of the author's report in the Session of the Presidium of the Russian Academy of Sciences in May, 1996. (Translated by E. Batova.) Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 8–32. January, 1997.     

Bola反离子诱导的高粘弹十六烷基硫酸钠蠕虫胶束溶液

利用稳态和频率扫描研究了十六烷基硫酸钠(SHS)与Bola盐(N,N’-双乙基二甲基-α,ω-乙烷溴化铵(Bola2Et)或N,N’-三甲基-α,ω-丁烷溴化铵(Bola4))混合体系的流变行为.实验结果表明两个体系均在45℃时形成了长蠕虫胶束,溶液呈现出高粘弹性,尤其是SHS/Bola2Et溶液表现出很高的弹性,零剪接粘度高达2520Pa’s,表观上呈现胶状.这些结果归因于在Bola反离子诱导下,表面活性剂SHS与Bola反离子形成了静电吸引的2:1结构复合物.由于这两个Bola反离子的联接链长度均短于季铵离子的静电平衡距离,因此形成的复合物在形状上有利于蠕虫胶束生成.作为对比,添加简单的四甲基铵反离子无法诱导SHS形成蠕虫胶束,溶液仅呈现低粘度.     

SHS of NbSi2: A Comparison Between Experiments and Simulations

Computer simulation results for the Self-propagating High-temperature Synthesis (SHS) of the intermetallic compound NbSi₂ are discussed in comparison with experiments for SHS of mechanically activated powders. The variation of wave speed of the propagation front is considered while varying Nb grain size and thermal conductivity of the starting mixture. A co-operating effect of these two parameters (due to the change in morphology of reactants after milling) is outlined.     

How "sticky" are short-range square-well fluids?

The aim of this work is to investigate to what extent the structural properties of a short-range square-well (SW) fluid of range lambda at a given packing fraction eta and reduced temperature T* = kBT/epsilon can be represented by those of a sticky-hard-sphere (SHS) fluid at the same packing fraction and an effective stickiness parameter tau(T*,lambda). Such an equivalence cannot hold for the radial distribution function g(r) since this function has a delta singularity at contact (r = sigma) in the SHS case, while it has a jump discontinuity at r = lambda sigma in the SW case. Therefore, the equivalence is explored with the cavity function y(r), i.e., we assume that [formula: see text]. Optimization of the agreement between y(SW) and y(SHS) to first order in density suggests the choice tau(T*,lambda) = [12(e(1/T* - 1)(lambda - 1)](-1). We have performed Monte Carlo (MC) simulations of the SW fluid for lambda = 1.05, 1.02, and 1.01 at several densities and temperatures T* such that tau(T*,lambda) = 0.13, 0.2, and 0.5. The resulting cavity functions have been compared with MC data of SHS fluids obtained by Miller and Frenkel[J. Phys.: Condens. Matter 16, S4901 (2004)]. Although, at given values of eta and tau, some local discrepancies between y(SW) and y(SHS) exist (especially for lambda = 1.05), the SW data converge smoothly toward the SHS values as lambda-1 decreases. In fact, precursors of the singularities of y(SHS) at certain distances due to geometrical arrangements are clearly observed in y(SW). The approximate mapping y(SW)-->y(SHS) is exploited to estimate the internal energy and structure factor of the SW fluid from those of the SHS fluid. Taking for y(SHS) the solution of the Percus-Yevick equation as well as the rational-function approximation, the radial distribution function g(r) of the SW fluid is theoretically estimated and a good agreement with our MC simulations is found. Finally, a similar study is carried out for short-range SW fluid mixtures.     

SHS of NbSi<Subscript>2</Subscript>: A Comparison Between Experiments and Simulations

Summary. Computer simulation results for the Self-propagating High-temperature Synthesis (SHS) of the intermetallic compound NbSi₂ are discussed in comparison with experiments for SHS of mechanically activated powders. The variation of wave speed of the propagation front is considered while varying Nb grain size and thermal conductivity of the starting mixture. A co-operating effect of these two parameters (due to the change in morphology of reactants after milling) is outlined.     

自蔓延高温合成材料制备新方法

本文从自蔓延高温合成(SHS) 术语的由来、引燃技术、八种常用的自蔓延高温合成技术、自蔓延高温合成研究历史、研究现状及其发展等方面对自蔓延高温合成进行综述。     

Investigation on Preparation and Anti-icing Performance of Superhydrophobic Surface on Aluminum Conductor

Aluminum is widely used in transmission lines, and the accumulation of ice on aluminum conductor may inflict serious damage such as tower collapse and power failure.In this study, super-hydrophobic surface (SHS) on aluminum conductor with micro-nanostructure was fabricated using the preferential etching principle of crystal defects.The surface microstructure and wettability were investigated by scanning electron microscope and contact angle measurement, respectively.The icing progress was observed with a self-made icing experiment platform at different environment temperature.The results showed that, due to jumping and rolling down of coalesced droplets from SHS of aluminum conductor at low temperature, the formation of icing on SHS could be delayed.Dynamic icing experiment indicated that SHS on aluminum conductor could restrain the formation of icing in certain temperature range, but could not exert influence on the accumulation of icing.This study offers new insight into understanding the anti-icing performance of actual aluminum conductor.     

Global mapping of equilibrium and transition structures on potential energy surfaces by the scaled hypersphere search method: applications to ab initio surfaces of formaldehyde and propyne molecules

Technical details of a new global mapping technique for finding equilibrium (EQ) and transition structures (TS) on potential energy surfaces (PES), the scaled hypersphere search (SHS) method (Ohno, K.; Maeda, S. Chem. Phys. Lett. 2004, 384, 277), are presented. On the basis of a simple principle that reaction pathways are found as anharmonic downward distortions of PES around an EQ point, the reaction pathways can be obtained as energy minima on the scaled hypersphere surface, which would have a constant energy when the potentials are harmonic. Connections of SHS paths between each EQ are very similar to corresponding intrinsic reaction coordinate (IRC) connections. The energy maximum along the SHS path reaches a region in close proximity to the TS of the reaction pathway, and the subsequent geometry optimization from the SHS maximum structure easily converges to the TS. The SHS method, using the one-after-another algorithm connecting EQ and TS, considerably reduces the multidimensional space to be searched to certain limited regions around the pathways connecting each EQ with the neighboring TS. Applications of the SHS method have been made to ab initio surfaces of formaldehyde and propyne molecules to obtain systematically five EQ and nine TS for formaldehyde and seven EQ and 32 TS for propyne.     

SHS metallurgy of high-entropy transition metal alloys

The first positive experience in synthesis of cast high-entropy alloys in the combustion mode, referred to as SHS metallurgy (SHS is self-propagating high-temperature synthesis) has been reported. Analysis of the data obtained enables the conclusion that the one-stage SHS method is promising for the production of cast metal materials using a new principle of formation of high-entropy polymetallic alloys.     

Method validation for measurement of hair nicotine level in nonsmokers

The development of strategies to address the growing worldwide burden of exposure to secondhand smoke (SHS) would be facilitated by sensitive and accurate methods for assessing SHS exposure. Hair provides a readily available matrix for assessing biomarkers of typical SHS exposure. We developed and applied an optimized analytical method using an isotope dilution gas chromatography-mass spectrometry (GC/MS) for hair nicotine measurement. The utility of this optimized method is illustrated by presenting data on SHS exposure of women and children from 31 countries. Using this isotope dilution method with spiked samples (3.3 ng/mg), we found that the greatest hair nicotine extraction efficiency was obtained with a 60 min shaking time. In the field study (n = 2400), a positive association was evident between hair nicotine concentrations from nonsmokers and higher numbers of cigarettes smoked per day in a household.     

Self-propagating high-temperature synthesis in the solid-phase triphenylphosphine-chloramine system

The macrokinetics and products of self-propagating high-temperture synthesis (SHS) in the solid-phase triphenylphosphine—chloramine system were studied by TGA-DTA, XRD, and³¹P NMR techniques. The temperature of SHS ignition (59°C), the velocity of reaction waves (1.6–5.0 mm s⁻¹), and the maximum temperature (155–239°C) in the SHS wave were measured. The chemical composition of the product obtained was established: phosphine oxide, triphenyl-N-(phenylsulfoyl)-phosphinimine, benzenesulfonamide, NaCl, and water. The scheme of chemical reactions occurring during SHS was proposed. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 301–305, February, 1999.     

Stability boundaries, percolation threshold, and two-phase coexistence for polydisperse fluids of adhesive colloidal particles

We study the polydisperse Baxter model of sticky hard spheres (SHS) in the modified mean spherical approximation (mMSA). This closure is known to be the zero-order approximation C0 of the Percus-Yevick closure in a density expansion. The simplicity of the closure allows a full analytical study of the model. In particular we study stability boundaries, the percolation threshold, and the gas-liquid coexistence curves. Various possible subcases of the model are treated in details. Although the detailed behavior depends upon the particularly chosen case, we find that, in general, polydispersity inhibits instabilities, increases the extent of the nonpercolating phase, and diminishes the size of the gas-liquid coexistence region. We also consider the first-order improvement of the mMSA (C0) closure (C1) and compare the percolation and gas-liquid boundaries for the one-component system with recent Monte Carlo simulations. Our results provide a qualitative understanding of the effect of polydispersity on SHS models and are expected to shed new light on the applicability of SHS models for colloidal mixtures.     

Molecule‐Membrane Interactions in Biological Cells Studied with Second Harmonic Light Scattering

The nonlinear optical phenomenon second harmonic light scattering (SHS) can be used for detecting molecules at the membrane surfaces of living biological cells. Over the last decade, SHS has been developed for quantitatively monitoring the adsorption and transport of small and medium size molecules (both neutral and ionic) across membranes in living cells. SHS can be operated with both time and spatial resolution and is even capable of isolating molecule‐membrane interactions at specific membrane surfaces in multi‐membrane cells, such as bacteria. In this review, we discuss select examples from our lab employing time‐resolved SHS to study real‐time molecular interactions at the plasma membranes of biological cells. We first demonstrate the utility of this method for determining the transport rates at each membrane/interface in a Gram‐negative bacterial cell. Next, we show how SHS can be used to characterize the molecular mechanism of the century old Gram stain protocol for classifying bacteria. Additionally, we examine how membrane structures and molecular charge and polarity affect adsorption and transport, as well as how antimicrobial compounds alter bacteria membrane permeability. Finally, we discuss adaptation of SHS as an imaging modality to quantify molecular adsorption and transport in sub‐cellular regions of individual living cells.     

Microemulstion synthesis of powders of water-soluble energy-saturated salts

The feasibility of preparing energy-saturated salts (NH₄NO₃, KNO₃, and NaBH₄) in powders with various particle sizes in microemulsion systems based on oxyethylated surfactant Tergitol NP-4 has been demonstrated. Powders were isolated by destroying microemulsions with acetone. The regions of micellar synthesis have been determined depending on the solubilization capacities and concentrations of the reagents and salts at a fixed Tergitol NP-4 concentration (0.25 mol/L). The morphologies and particle sizes of the thus-prepared salt powders were characterized by scanning electron microscopy (SEM), X-ray powder diffraction, differential scanning calorimetry (DSC), differential thermal analysis (DTA), and thermogravimetry; the hydrodynamic radii of microemulsions were characterized by photon-correlation spectroscopy.     

A fundamental measure theory for the sticky hard sphere fluid

We construct a density functional theory (DFT) for the sticky hard sphere (SHS) fluid which, like Rosenfeld's fundamental measure theory (FMT) for the hard sphere fluid [Y. Rosenfeld, Phys. Rev. Lett. 63, 980 (1989)], is based on a set of weighted densities and an exact result from scaled particle theory (SPT). It is demonstrated that the excess free energy density of the inhomogeneous SHS fluid Φ(SHS) is uniquely defined when (a) it is solely a function of the weighted densities from Kierlik and Rosinberg's version of FMT [E. Kierlik and M. L. Rosinberg, Phys. Rev. A 42, 3382 (1990)], (b) it satisfies the SPT differential equation, and (c) it yields any given direct correlation function (DCF) from the class of generalized Percus-Yevick closures introduced by Gazzillo and Giacometti [J. Chem. Phys. 120, 4742 (2004)]. The resulting DFT is shown to be in very good agreement with simulation data. In particular, this FMT yields the correct contact value of the density profiles with no adjustable parameters. Rather than requiring higher order DCFs, such as perturbative DFTs, our SHS FMT produces them. Interestingly, although equivalent to Kierlik and Rosinberg's FMT in the case of hard spheres, the set of weighted densities used for Rosenfeld's original FMT is insufficient for constructing a DFT which yields the SHS DCF.     

Study on the Preparation of Mercaptoacetic Acid-modified Heterophylla Shell and Its Application in Separation and Enrichment of Pb2+ in Environmental Samples

To increase the adsorption capacity of the Corylus heterophylla Fisch(HS) for Pb²⁺, HS was chemically modified using NaOH aqueous solution and 95% ethanol and was labeled as SHS; then SHS was chemically modified using mercaptoacetic acid. The SHS modified with mercaptoacetic acid(MHS) was characterized using FTIR, SEM, and XPS. The results indicated that the -SH group was present on MHS, and after Pb²⁺ adsorption, the absorption value of the characteristic peak of the -SH group decreased. The adsorption and desorption properties of this functionalized material were investigated as well as the influences of parameters, such as pH value, type of desorption reagent, dosage, flow rate and maximum sample volume. The Pb²⁺ adsorption of MHS reached a maximum with pH>5. The experimental data of Pb²⁺ adsorption using MHS were fitted using the Langmuir isothermal adsorption model, and a maximum adsorption capacity of 61.54 mg/g was obtained. This was much higher than the adsorption capacity of SHS before modification with the thiol group. After adsorption, MHS was desorbed using a 0.2 mol/L HCl solution, and the percent of desorption was higher than 99%. MHS was used as a solid-phase extractant in the analysis and determination of Pb²⁺ content in food and water samples, and the enrichment times achieved 150-fold.     

Solubilities of ionic surfactants in aqueous polymer solutions

Summary Solubility of ionic surfactants in water have been found to increase with added amount of nonionic hydrophilic polymers when both are capable of forming watersoluble complexes. Experiments were carried out with sodium hexadecyl sulfate (SHS) and hexadecyl amine hydrochloride (HAC) below theKrafft points of the respective surfactants. The solubility increment of the surfactants brought about by the polymers depends upon the kind of polymers, their molecular weight, concentration and temperature. The results have been interpreted on the basis of the amount of surfactants bound to the polymers and by the properties of the polymer-surfactant complexes formed. It is noteworthy that the anionic surfactant (SHS) can be bound to polymers much more extensively than the cationic surfactant (HAC).

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Zusammenfassung Die L?slichkeit von ionischen Benetzern in Wasser w?chst mit dem zugefügten Betrag an nicht-ionischen hydrophilen Polymeren, wenn beide zusammen wasserl?sliche Komplexe büden k?nnen. Versuche wurden mit Natrium-hexadecyl-sulfat (SHS) und Hexadecylamin-hydrochlorid (HAC) ausgeführt, und zwar unter denKrafft-Punkten der bezüglichen Benetzer. Das L?slichkeitsinkrement der Benetzer, gegeben durch die Polymeren, h?ngt von der Art des Polymeren, dessen Molekulargewicht, Konzentration und Temperatur ab. Die Ergebnisse werden interpretiert auf der Grundlage des Betrages an Benetzer, der an das Polymere gebunden ist, und durch die Eigenschaften des Komplexes Polymer/Benetzer. Es ist bemerkenswert, da? der anionische Benetzer (SHS) viel st?rker an das Polymere gebunden werden kann als der kationische Benetzer (HAC).

     

Self-organization of a sulfonamido-porphyrin in Langmuir monolayers and Langmuir-Blodgett films

Langmuir monolayers (LM) and Langmuir-Blodgett (LB) films of pure lipophilic meso-tetra(4-dodecylaminosulfophenyl)porphyrin (PC12) and mixed with the anionic surfactant sodium hexadecylsulfate (SHS) were studied. The molecular packing and structure of PC12 and PC12-4SHS with variable surface pressure were investigated by surface pressure-area measurements, steady-state absorption, fluorescence emission and anisotropy, as well as by fluorescence lifetime imaging microscopy (FLIM). At low surface pressure, the porphyrin molecules are organized with the rings tilted on the water surface whereas at high surface pressure the porphyrin rings achieve a more perpendicular arrangement. Using the FLIM images a gradual change of aggregates into large "islands" is observed. Different patterns are observed in the pure PC12 multilayer films (n = 3 and 5) with ordered patches superimposed which are not observed in the PC12-4SHS multilayer LB films.     

溶胶-凝胶自蔓燃法制备铁掺杂纳米TiO2光催化剂

为了研究溶胶-凝胶自蔓燃法（SHS）制备的铁掺杂纳米TiO2的光催化活性,以TiCl4为原料制备了Fe3+掺杂TiO2光催化剂,分别在低压汞灯、中压汞灯和太阳光照射下进行了亚甲基蓝降解实验。 XRD和SEM显示,以TiCl4为前驱体,n(Ti)∶n(柠檬酸)∶n(NH4NO3)=1∶3∶5,经250 ℃自蔓燃和500 ℃热处理后,TiO2呈疏松、多孔的灰白色锐钛型粉体,粒径约为20 nm;在不同光源作用下,掺铁摩尔分数为0.02%的TiO2催化活性均最大;亚甲基蓝溶液在掺铁分数为0.02%的TiO2作用下,经太阳光照90 min后降解率达到了96.1%,为纯TiO2的1.78倍。