New Aspects of Impact Reactivity of Polynitro Compounds. Part IV. Allocation of Polynitro Compounds on the Basis of their Impact Sensitivities

A linear relationship has been found between the drop energies of impact sensitivity detected by sound and the drop energies of “the first reaction” for 28 polynitro compounds. In the sense of this relationship, the compounds studied fall into three classes. The reason of the said diversification lies in the decomposition reaction rate at the temperature of the beginning of their thermolysis. It is stated that some relationship exists between vibrational excitation by impact, on the one hand, and thermal activation of the molecules of energetic materials, on the other one.     

New Aspects of Impact Reactivity of Polynitro Compounds,Part II. Impact Sensitivity as “the First Reaction” of Polynitro Arenes

The impact reactivity (“the first reaction”) of 22 polynitro arenes was expressed as the drop energy, E_dr, required for 50 percent initiation probability. Relationships have been found between the E_dr values and heats of fusion, on the one hand, and ¹³C NMR chemical shifts of carbon atoms in reaction centers, on the other hand. On the basis of the said relationships it was stated that the impact reactivity of polynitro arene molecules depends on the electronic configuration within their reaction centers and on the intensity of their intermolecular interactions in the molecular crystals. The relationships found make it possible to specify this reaction center which is illustrated by the molecules of 1,5‐dinitronaphthalene and 3,3′‐dimethyl‐2,2′,4,4′,6,6′‐hexanitrodiphenyl sulfide.     

A New General Correlation for Predicting Impact Sensitivity of Energetic Compounds

This paper describes an improved simple model for prediction of impact sensitivity of different classes of energetic compounds containing nitropyridines, nitroimidazoles, nitropyrazoles, nitrofurazanes, nitrotriazoles, nitropyrimidines, polynitroarenes, benzofuroxans, polynitroarenes with α‐CH, nitramines, nitroaliphatics, nitroaliphatic containing other functional groups, and nitrate energetic compounds. The model is based on some molecular structural parameters. It is applied for 90 explosives, which have different molecular structures. The predicted results are compared with outputs of complex neural network approach as one of the best available methods. Root mean squares (rms) of deviations of different energetic compounds are 24 and 49 cm, corresponding to 5.88 and 12.01 J with 2.5 kg dropping mass, for new and neural network methods, respectively. The novel model also predicts good results for eight new synthesized and miscellaneous explosives with respect to experimental data.     

Prediction of Sensitivity of Energetic Compounds with a New Computer Code

Impact, electrostatic, and shock sensitivities of energetic compounds are three important parameters for the assessment of hazardous energetic materials. A novel easy to handle and user‐friendly computer code, written in Visual Basic, is introduced to predict these parameters, by solely using the molecular structure of an energetic molecule. It is able to predict impact sensitivity for different types of energetic compounds including nitropyridines, nitroimidazoles, nitropyrazoles, nitrofurazanes, nitrotriazoles, nitropyrimidines, polynitro arenes, benzofuroxans, polynitro arenes with α‐CH, nitramines, nitroaliphatics, nitroaliphatic containing other functional groups, and nitrate energetic compounds. It can also provide reliable results for electrostatic and shock sensitivities of some classes of high explosives including nitroaromatic and nitramine compounds. The prediction of this code give good values for some newly reported energetic compounds, where experimental data are available.     

新型亚磺酰胺类化合物在照相乳剂中的应用

研究了系列新型亚磺酰胺类化合物与增感染料在实用照相乳剂中的超增感作用。实验结果表明，照相乳剂的感光度有明显的提高，增感效果高于某些常用的超增感剂。通过ＥＳＲ信号及极谱半波电位的测试，对超增感机理进行了解释。     

Charge Density Distribution,Electrostatic Properties,and Impact Sensitivity of the High Energetic Molecule TNB: A Theoretical Charge Density Study

A quantum chemical calculation and a charge density analysis have been performed on the energetic molecule trinitrobenzene (TNB) to characterize its bond strength and to relate the bond topological parameters with the impact sensitivity. The optimized geometry of the molecule was calculated by the density functional method B3P86 with the basis set 6‐311G**. The bond topological analysis predicts a significantly low bond electron density (∼1770 e nm⁻³) as well as Laplacian of electron density (−1.67×10⁶ e nm⁻⁵) for C N bonds. This low value of the Laplacian indicates, the charges of these bonds are highly depleted, which confirms that these are the weakest bonds in the molecule. The N=O bonds bear a high negative value of Laplacian, reflecting that the bond charges are highly concentrated. The isosurface of the molecular, electrostatic potential (ESP) shows large electronegative regions at the vicinity of  NO₂ groups. Further analysis of ESP in the bonding region allows predicting the impact sensitivity. A sound relationship has been found between the ESP at the mid point of the bonds and its bond charge depletion. The positive ESP at the mid points of highly charge depleted C NO₂ bonds reveals that these bonds are the sensitive bonds in the molecule.     

Basic Methods for Preparation of Liposomes and Studying Their Interactions with Different Compounds,with the Emphasis on Polyphenols

Studying the interactions between lipid membranes and various bioactive molecules (e.g., polyphenols) is important for determining the effects they can have on the functionality of lipid bilayers. This knowledge allows us to use the chosen compounds as potential inhibitors of bacterial and cancer cells, for elimination of viruses, or simply for keeping our healthy cells in good condition. As studying those effect can be exceedingly difficult on living cells, model lipid membranes, such as liposomes, can be used instead. Liposomal bilayer systems represent the most basic platform for studying those interactions, as they are simple, quite easy to prepare and relatively stable. They are especially useful for investigating the effects of bioactive compounds on the structure and kinetics of simple lipid membranes. In this review, we have described the most basic methods available for preparation of liposomes, as well as the essential techniques for studying the effects of bioactive compounds on those liposomes. Additionally, we have provided details for an easy laboratory implementation of some of the described methods, which should prove useful especially to those relatively new on this research field.     

Comparing the Antileishmanial Activity of Gold(I) and Gold(III) Compounds in L. amazonensis and L. braziliensis in Vitro

Abstract : A series of mononuclear coordination or organometallic Au^I/Au^III complexes ( 1 – 9 ) have been comparatively studied in vitro for their antileishmanial activity against promastigotes and amastigotes, the clinically relevant parasite form, of Leishmania amazonensis and Leishmania braziliensis. One of the cationic Au^I bis-N-heterocyclic carbenes ( 3 ) has low EC₅₀ values (ca. 4 μM) in promastigotes cells and no toxicity in host macrophages. Together with two other Au^III complexes ( 6 and 7 ), the compound is also extremely effective in intracellular amastigotes from L. amazonensis. Initial mechanistic studies include an evaluation of the gold complexes′ effect on L. amazonensis’ plasma membrane integrity.     

Temperature Drop Turbidimetry as a Means for the Rapid Determination of the Polydispersity of Polymers Part III. Polyethylene

The molecular weight averages of narrow and broad distribution polyethylene have been determined by controlled precipitation from a mixed solvent of xylene/n-hexanol in the temperature range 433 to 33K. Estimates of the distribution (D) which compared unfavourably with and considerably under-estimated those determined by gel permeation chromatography (g.p.c.) were obtained by a calibration procedure between the temperature of initial onset of precipitation and the weight average molecular weight which have been used previously _1,2 to characterise turbidimetric curves. However, the calibration curves gave an accurate estimate of the weight average molecular weight. There was also an accurate correlation between the reciprocal of the breadth of the turbidity-temperature curves as measured by 1/T_max (dτ/dT) ^?1 i.e. (S)^?1, and the logarithm of the g.p.c. dispersity which enabled the breadth of distribution to be determined. With these two correlations molecular weight characteristics could be determined rapidly which compared favourably with g.p.c. data. The method has been applied to fractions obtained for 3 methods of fractionating polyethylene in order to compare their relative efficiencies.     

A study on the preparation of supported metal oxide catalysts using JRC-reference catalysts. I. Preparation of a molybdena–alumina catalyst. Part 4. Preparation parameters and impact index

The effects of the volume and pH of the impregnation solution and of the calcination conditions were examined on the physicochemical and catalytic properties of a 13 wt% MoO₃/Al₂O₃ extrudate catalyst. The Al₂O₃ support and drying procedures (static conditions without flowing air) were fixed in the preparations. In the present series of catalysts, the amount of crystalline MoO₃ was marginally small. It was found that the dispersion of Mo oxide species increased as the volume of the impregnation solution increased, gradually approaching a maximum value. The increase in pH (2–8) of the impregnation solution was found to reduce the dispersion of Mo oxide species. The Mo dispersion increased slightly for the impregnation catalysts as the calcination temperature increased (673–873 K), whereas it decreased for the equilibrium adsorption catalysts. The effects of the calcination atmosphere (with or without flowing air, or with flowing humid air) were very small on the dispersion of Mo oxide species under the present preparation conditions. On the other hand, the methanol oxidation activity of MoO₃/Al₂O₃ was sensitive to the preparation parameters examined here. It was demonstrated by means of EPMA and XPS that a considerable migration of Mo took place during the calcination.

In the present study on the preparation of a 13 wt% MoO₃/Al₂O₃ catalyst, an impact index is proposed to measure the magnitude of the effects of the respective parameter(s) on the physicochemical and catalytic properties. With the Mo dispersion, the effects of the preparation parameter decreased in the order, surface area of the support >> drying process > volume of the impregnation solution > pH, calcination temperature and atmosphere. The size of the impact index for the dispersion of Mo sulfide species is 70–75% of that for the Mo oxide species. The HDS activity of the catalyst was less affected by the preparation parameters than the Mo sulfide dispersion. The preparation parameters affected the segregation of Mo on the outer surface of extrudates in a decreasing order: drying process > volume of the impregnation solution > pH, calcination conditions. It was found that the oxidation of methanol was affected most intensely by the drying procedures. The volume of the impregnation solution, calcination conditions and pH of the impregnation solution also strongly affected the oxidation activity. The impact index suggests that the sensitivity to the preparation variables of the physicochemical and catalytic properties of MoO₃/Al₂O₃ decreases in the order, methanol oxidation activity > surface Mo segregation > Mo oxide dispersion > Mo sulfide dispersion > HDS activity.     

Modelling of a moving bed furnace for the production of uranium tetrafluoride. Part 2: Application of the model

The French nuclear fuel making route uses, prior to enrichment, uranium tetrafluoride UF₄ obtained from the reduction, followed by hydrofluorination of uranium trioxide UO₃. These two steps are carried out in a specific reactor known as a moving bed furnace. We developed a steady-state numerical model of the moving bed furnace, described in Part 1. In the Part 2, calculation results for a reference set of operating parameters of the furnace are presented in term of temperature, reaction rates, solid and gas compositions. Results analysis enlightens the detail of the furnace behaviour in its different zones. Unknown features have been revealed, such as thermodynamic limitation of the hydrofluorination reaction in the hot core of the moving bed. A sensibility study of various operating parameters shows how some can influence the UF₄ quality and underlines the strong coupling between the different zones of the furnace. Finally, the model is applied to define an optimal temperature progression in the furnace and suggests geometrical modifications. Besides, the validity of using the law of additive reaction times for calculating the reaction rates in such a reactor model has been checked for the first time against a numerical grain model.     

Elastic Properties of Nickel-Based Anodes for Solid Oxide Fuel Cells as a Function of the Fraction of Reduced NiO

The changes in porosity and elastic moduli of YSZ-containing nickel-based anode materials for solid oxide fuel cells were studied as a function of the fraction of reduced NiO. Anode samples were reduced in a gas mixture of 4% hydrogen and 96% argon for different periods of time at 800°C and their Young's and shear moduli were determined afterward at room temperature using resonant ultrasound spectroscopy and impulse excitation. It was found that the magnitude of Young's and shear moduli decreased significantly with increasing fraction of reduced NiO and that the magnitude of the elastic moduli of a fully reduced Ni–YSZ anode was ∼45% lower than that of unreduced NiO–YSZ. Because the elastic moduli of NiO are close to those of Ni, the observed decrease in the magnitude of the elastic moduli was found to be caused mainly by the significant increase in the porosity of the sample as a result of NiO reduction. Expressions are presented for the amount of porosity and the magnitude of the elastic moduli as a function of the fraction of reduced NiO.     

Combination of a hydroxy‐functional organophosphorus oligomer and a multifunctional carboxylic acid as a flame retardant finishing system for cotton: Part I. The chemical reactions

Multifunctional carboxylic acids, such as 1,2,3,4‐butanetetracarboxylic acid (BTCA), have been used as crosslinking agents for cotton cellulose to produce wrinkle‐resistant cotton fabrics and garments. Polycarboxylic acids were used to bond hydroxy‐functional organophosphorus oligomer to cotton, thus imparting durable flame retarding properties to the cotton fabric. This research investigated the chemical reactions between the hydroxy‐functional organophosphorus compound and BTCA on cotton. BTCA crosslinks cotton cellulose through the formation of a 5‐membered cyclic anhydride intermediate and esterification of the anhydride with cellulose. In the presence of the organophosphorus compound, BTCA reacts with both the organophosphorus compound and cellulose, thus functioning as a binder between cotton cellulose and the organophosphorus compound and making the flame retarding system durable to laundering. The cotton fabric treated by the combination of the organophosphorus compound and BTCA demonstrated lower wrinkle resistance and less tensile strength loss than that treated by BTCA alone. The phosphorus retention on the cotton fabric after one home laundering cycle was approximately 70%. Copyright © 2003 John Wiley & Sons, Ltd.     

Combination of a hydroxy‐functional organophosphorus oligomer and a multifunctional carboxylic acid as a flame retardant finishing system for cotton: Part II. Formation of calcium salt during laundering

Multifunctional carboxylic acids, such as 1,2,3,4‐butanetetracarboxylic acid (BTCA), were used to bond a hydroxy‐functional organophosphorus oligomer (FR) to cotton fabric in the presence of a catalyst, such as sodium hypophosphite (NaH₂PO₂). Previously, it was found that the cotton fabric treated with FR and BTCA showed a high level of phosphorus retention after one home laundering cycle. However, the flame retardant properties quickly deteriorated as the number of home laundering cycles was increased. In this research, it was found that the free carboxylic acid groups bound to the cotton fabric form an insoluble calcium salt during home laundering, thus diminishing the flame retardant properties of the treated cotton fabric. It was also found that the free carboxylic acid groups on the treated cotton fabric were esterified by triethanolamine (TEA), and that the formation of calcium salt on the fabric was suppressed by the esterification of the free carboxylic acid groups by TEA. The cotton fabric treated with BTCA and the hydroxy‐functional organophosphorus oligomer significantly improved its flame retardance when a new catalyst system consisting of hypophosphorous acid (H₃PO₂) and TEA was used in the system. Copyright © 2003 John Wiley & Sons, Ltd.     

Alkanol removal from the apolar phase of a two-liquid phase bioconversion system. Part 2: Effect of fermentation medium on batch distillation

In two-liquid phase fermentations organic substrates and/or products are dissolved in an apolar phase while microorganisms are suspended in an aqueous medium. The effect of aqueous phase contaminants in the apolar phase on the separation of products from the apolar phase by batch distillation is described in this paper. Various amounts of polar phase, emulsified apolar phase and microorganisms normally present in the two-liquid fermentation medium were added to the organic phase. The recovery performance of a distillation unit in separating 1-octanol from such contaminated apolar phases was determined. Further, the bulk properties of the emulsified apolar phase, such as its composition, the nature and the stability of the emulsion were analysed. It was found that the distillation performance is very sensitive to the presence of fermentation media in the organic phase. The energy cost per kg product recovered was almost doubled for only small additions of fermentation impurities. The emulsified apolar phase was shown to be kinetically, but not thermally, stable. Based on these results a suitable apolar phase separation process before distillation can be developed, taking into account energy costs for phase separation and subsequent distillation, to optimize the overall downstream product purification process. © 1998 SCI     

Effect of the mode of heat withdrawal on the asymmetry of temperature profiles in reverse-flow reactors. Catalytic combustion of methane as a test case

Results of simulations are presented concerning a reverse-flow reactor for the catalytic combustion of methane that occurs in coal-mine ventilation air. Two variants of heat withdrawal are analysed. The simulations show that a relation exists between the method for heat withdrawal and the asymmetry in the profiles of the catalyst temperature over half-cycles of flow reversal. Too strong asymmetry impairs the efficient utilization of the heat produced. The results reveal that the recovery of heat by hot gas withdrawal from the central part of the reactor, and then, the introduction of the gas into a boiler wherein it is cooled to about 333 K (60 °C) guarantee more favourable symmetry of the half-cycle profiles and much better utilization conditions than the direct withdrawal of heat from the mid-section of the reactor (central cooling).     

A Study of Chemical Interactions at the Stainless Steel/Polymer Interface by Infrared Spectroscopy. Part 2: Mechanical Properties and Study of the Interphase

The interaction of a thermoplastic ethylene-maleic anhydride copolymer with stainless steel has been studied by infrared spectroscopic techniques (FTIR). The aim was to improve understanding of the reaction processes at the steel/polymer interface in order to optimize the quality of assemblies in terms of adhesion and durability under the conditions which will subsequently be those of normal operation.

Steel/polymer associations have been tested after being submitted to several different conditions of treatment and aging in order to understand the various phenomena which occur at the steel/polymer interphase.

Mechanical behavior improves after heat treatment, and similar conclusions can be transposed to the structure after use, such as in domestic equipment. Modifications in interactions between stainless steel and polymer are caused first by the chemical reactivity of anhydride functions, and second by the mobility of organic chains which reorganize at the interphase.

Analysis of failure surfaces shows several correlations between the mechanical behavior and the chemical nature of residual polymer on the metal substrate. Localization of failure depends on aging conditions and can be explained by minimization of interfaical energy between the polar structure of the metal surface and the organic chains.