bluuebunny/crossref_metadata_2025 huggingface dataset:
Blue‐emitting poly(1,3‐phenylenevinylene) derivatives: Effect of substitution patterns on optical properties
Authors: Liao Liang , Ding Liming , Karasz Frank E. , Pang Yi
Published: May 2005

Blue‐emitting poly{[5‐(diphenylamino)‐1,3‐phenylenevinylene]‐alt‐(2‐hexyloxy‐5‐methyl‐1,3‐phenylenevinylene)} (3), poly{[5‐bis‐(4‐butyl‐phenylamino)‐1,3‐phenylenevinylene]‐alt‐(1,3‐phenylene vinylene)} (4), and poly(2‐hexyloxy‐5‐methyl‐1,3‐phenylenevinylene) (5) were synthesized by the Wittig–Horner reaction. Although polymers 3–5 possess fluorescent quantum yields of only 13–34% in tetrahydrofuran solution, their films appear to be highly luminescent. Attachments of substituents tuned the emission color of thin films to the desirable blue region (λmax = 462–477 nm). Double‐layer light‐emitting‐diode devices with 3 and 5 as an emissive layer produced blue emission (λem = 474 and 477 nm) with turn‐on voltages of 8 and 11 V, respectively. The external quantum efficiencies were up to 0.13%. © 2005Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 2800–2809, 2005
Fabrication of novel conjugated polymer nanostructure: Porphyrins and fullerenes conjugately linked to the polyacetylene backbone as pendant groups
Authors: Wang Ning , Li Yongjun , Lu Fushen , Liu Yang , He Xiaorong , Jiang Li , Zhuang Junpeng , Li Xiaofang , Li Yuliang , Wang Shu , Liu Huibiao , Zhu Daoben
Published: May 2005

A new series of conjugated polyacetylenes with conjugately linked fullerene and porphyrin groups as pendant units were prepared by a copolymerization reaction catalyzed by chloronorbornadiene rhodium(I)dimer‐triethylamine ([Rh(nbd)Cl]2‐NEt3) in anhydrous CHCl3. These polymers were characterized with UV–vis spectroscopy, fluorescence spectroscopy, and voltammetry. Scanning electron microscopy indicated that the morphology of the copolymers consisted of uniform nanorods with a diameter of about 100 nm and a length of about 300 nm. Thin films of the copolymers produced steady and prompt photocurrent at an irradiation of 20.0 mW cm−2 of white light, which was higher than that of a mixture of poly[5‐(4‐Ethynyl‐phenyl)‐10,15,20‐tris(4‐carbomethoxyphenyl)porphyrin zinc] and C60. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 2851–2861, 2005
Reversible addition–fragmentation chain transfer/miniemulsion polymerization of butyl methacrylate in the presence of β‐cyclodextrin
Authors: Zhang Feng , Ni Peihong , Xiong Qingfeng , Yu Zhangqing
Published: May 2005

In the presence of β‐cyclodextrin (β‐CD), reversible addition–fragmentation chain transfer (RAFT) polymerization has been successfully applied to control the molecular weight and polydispersity [weight‐average molecular weight/number‐average molecular weight (Mw/Mn)] in the miniemulsion polymerization of butyl methacrylate, with 2‐cyanoprop‐2‐yl dithiobenzoate as a chain‐transfer agent (or RAFT agent) and 2,2′‐azoisobutyronitrile (AIBN) as an initiator. β‐CD acted as both a stabilizer and a solubilizer, assisting the transportation of the water‐insoluble, low‐molecular‐weight RAFT agent into the polymerization loca (i.e., droplets or latex particles) and thereby ensuring that the RAFT agent was homogeneous in the polymerization loca. The polymers produced in the system of β‐CD exhibited narrower polydispersity (1.2 < Mw/Mn < 1.3) than those without β‐CD. Moreover, the number‐average molecular weight in the former case could be controlled by a definite amount of the RAFT agent. Significantly, β‐CD was proved to have a favorable effect on the stability of polymer latex, and no coagulum was observed. The effects of the concentrations of the RAFT agent and AIBN on the conversion, the molecular weight and its distribution, and the particle size of latices were investigated in detail. Furthermore, the influences of the variations of the surfactant (sodium dodecyl sulfate) and costabilizer (hexadecane) on the RAFT/miniemulsion polymerization were also studied. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 2931–2940, 2005
Influence of alkyl chains of amphiphilic hyperbranched poly(ester amine)s on the phase‐transfer performances for acid dye and the aggregation behaviors at the interface
Authors: Tang Liming , Fang Yu , Tang Xianlai
Published: May 2005

Hyperbranched poly(ester amine) (HPEA) with terminal secondary amine groups was synthesized by the Michael addition reaction between piperazine and trimethylolpropanetriacrylate with a molar ratio of 13:6. It was further reacted with a series of aliphatic acid chlorides, including stearoyl chloride, dodecanoyl chloride, and octanoyl chloride, to yield three modified amphiphilic hyperbranched polymers, which were termed HPEA‐C18, HPEA‐C12, and HPEA‐C8, respectively. These polymers were characterized with Fourier transform infrared, 1H NMR, gel permeation chromatography, and differential scanning calorimetry measurements. Because of the existence of interior tertiary amine groups, the modified amphiphilic polymers were used as host molecules to extract the guest acid dye, methyl orange (MO), from the aqueous layer to the organic layer on the basis of the acid–base interaction. The influences of the pH of the aqueous layer and the length of the alkyl chains in the modified polymers on the phase‐transfer performances were investigated. The results indicated that more MO molecules could be extracted at a lower pH because of the formation of more quaternary ammonium ions within the host molecules. As the length of the alkyl chains in the modified polymers increased, both the transfer capability and the intermolecular aggregation at the interface were enhanced. The extracted MO could be reversibly released from the organic layer to the aqueous layer under basic conditions. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 2921–2930, 2005
Flame‐retardant epoxy resins with high glass‐transition temperatures from a novel trifunctional curing agent: Dopotriol
Authors: Cai Sheng Xiong , Lin Ching Hsuan
Published: May 2005

A novel phosphorus‐containing trifunctional novolac (dopotriol) was synthesized through the addition reaction of 9,10‐dihydro‐9‐oxa‐10‐phosphaphenanthrene 10‐oxide and rosolic acid. The structure of dopotriol was confirmed with NMR spectroscopy and elemental analyses. The dopotriol was blended with phenol novolac in the ratios of 10/0, 8/2, 6/4, 4/6, 2/8, and 0/10 to serve as a curing agent for diglycidyl ether of bisphenol A. Thermal properties, such as the glass‐transition temperature, thermal decomposition temperature, and flame retardancy, moisture absorption, and dielectric properties of the cured epoxy resins were evaluated. The activity and activation energy of curing were studied with the methods of Kissinger and Ozawa by dynamic differential scanning calorimetry scans. The glass‐transition temperatures of the cured epoxy resins were 138–159 °C, increasing with the phosphorus content. This is rarely seen in the literature after the addition of a flame‐retardant element. The flame retardancy increased with the phosphorus content, and a UL‐94 V‐0 grade was achieved with a phosphorus content of 1.87%. Similar dielectric properties and moisture absorption were observed for these phosphorus‐containing epoxy resins, and this implied that the addition of phosphorus to epoxy did not affect the dielectric properties and moisture absorption. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 2862–2873, 2005
Preparation of polymer/silica composite nanoparticles bearing carboxyl groups on the surface via emulsifier‐free emulsion copolymerization
Authors: Zeng Zhong , Yu Jian , Guo Zhao‐Xia
Published: May 2005

Polymer/silica organic/inorganic composite nanoparticles bearing carboxyl groups on the surface were prepared via the emulsifier‐free emulsion copolymerization of methyl methacrylate and sodium methacrylate (NaMA). Carboxyl groups were generated by the addition of hydrochloric acid at the end of the copolymerization. Two methods of NaMA addition were studied: batch and two‐stage procedures. The batch procedure allowed only a limited number of carboxyl groups to effectively bond to the composite nanoparticles. In contrast, the number of carboxyl groups could be altered over a wide range with the two‐stage procedure. Fourier transform infrared spectroscopy and chemical titration were independently used to quantify the number of carboxyl groups, giving values close to each other and to the feed. A kinetic study indicated that the copolymerization followed a mechanism different than that found earlier. The average size of the composite nanoparticles was approximately 40 nm, as measured by both transmission electron microscopy (TEM) and laser scattering, and their polydispersity index was close to 1, indicating a fairly narrow size distribution. TEM photographs of the composite nanoparticles showed a multilayered core–shell structure with one silica bead as the core and with poly(methacrylate acid) as the outmost shell. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 2826–2835, 2005
Solution route to inorganic nanobelt‐conducting organic polymer core‐shell nanocomposites
Authors: Xu Jian , Li Xiaolin , Liu Junfeng , Wang Xun , Peng Qing , Li Yadong
Published: May 2005

A facile and versatile solution‐based approach was developed to prepare semiconductor metal oxide nanobelt‐conducting organic polymer core‐shell nanocomposites. Well‐defined nanobelts of several types of oxide nanobelts were combined with conducting polymer [polypyrrole (PPy) and polyaniline (PANi)] via in situ polymerization in aqueous solution to obtain a new type of inorganic–organic composite nanostructure. Samples were characterized by using X‐ray diffraction, scanning electron microscopy, transmission electron microscopy, Fourier transform infrared, electron energy loss spectra, high‐resolution transmission electron microscopy, and ultraviolet–visible techniques. Electron energy loss spectra revealed the existence of CC and CN bonds in coating layers to prove the encapsulation of PPy or PANi. The red‐shift of absorption band at high‐energy was observed for PPy‐encapsulated composites via ultraviolet–visible spectroscopy, and significant absorption band shifts were also encountered to PANi‐encapsulated composites, which suggest possibilities of band‐gap tuning of such metal oxide‐conducting polymer composites to be applied especially in solar cell devices. However, the sacrifice of nanobelts‐core led to hollow structures of PPy and PANi, which expands the synthetic strategies to prepare conducting polymer nanotubes. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 2892–2900, 2005
2‐[(5‐methylisoxazol‐3‐yl)amino]‐2‐oxo‐ethyl methacrylate with glycidyl methacrylate copolymers: Synthesis, thermal properties, monomer reactivity ratios, and antimicrobial activity
Authors: Soykan Cengiz , Güven Şükran , Coşkun Ramazan
Published: May 2005

We report the monomer reactivity ratios for copolymers of glycidyl methacrylate (GMA) and a reactive monomer, 2‐[(5‐methylisoxazol‐3‐yl)amino]‐2‐oxo‐ethyl methacrylate (IAOEMA), using the Fineman–Ross method, the Kelen–Tüdös method, and a nonlinear error invariablemodel method with the computer program RREVM. Copolymers were obtained by radical polymerization initiated by α,α′‐azobisisobutyronitrile in a 1,4‐dioxane solution and were analyzed by Fourier transform infrared, 1H NMR, and gel permeation chromatography. Elemental analysis was used to determine the molar fractions of GMA and IAOEMA in the copolymers. The reactivity ratios indicated a tendency toward random copolymerization. The polydispersity indices of the polymers, determined with gel permeation chromatography, suggested a strong tendency for chain termination by disproportionation. The thermal behaviors of copolymers with various compositions were investigated by differential scanning calorimetry and thermogravimetric analysis. The glass‐transition temperature of the copolymers increased with increasing IAOEMA content in the copolymers. Also, the apparent thermal decomposition activation energies were calculated by the Ozawa method with a Setaram Labsys thermogravimetric analysis thermobalance. All the products showed moderate activity against different strains of bacteria and fungi. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 2901–2911, 2005
Measurement of the Influence of Directed Particle motion on the turbulent particle deposition velocity by means of laser‐doppler anemometry
Authors: Holländer Werner , Pohlmann Gerhard
Published: May 2005

The dry deposition of particles from the atmosphere is not well understood for reasons of surface variabilities and mutual interactions between surface and particles. However, even relatively simple influences of physical parameters have so far resisted successful parameterization, although some progress has been achieved. There is no general way to determine the relative contributions of stochastic turbulent and Brownian diffusion and directed motions (i. e. sedimentation) to the total deposition velocity since they contribute in a nonlinear manner to the total deposition velocity. The directed motion is an unknown function of atmospheric turbulence, the particle diffusion coefficient Dp and the sum of all directed particle motions by thermophoresis, diffusiophoresis, photophoresis, electrophoresis, sedimentation etc. Practically nothing is known about the action of the first three forces and even the easily accessible electrophoresis has not been considered relevant for deposition of atmospheric particles. Because it is relatively easy to change an electric field with all other parameters kept constant and measure the absolute difference in total deposition velocity the following experimental Laser‐Doppler study was intended to show the feasibility of the field‐changing‐technique and the magnitude of the effects without quantitatively determining the electrical mobility distribution as a function of particle size.
High‐Temperature Evaporation Rates of Solid KBr and NH4Cl aerosol particles
Authors: Timmler JÜRgen , Roth Paul
Published: May 2005

The evaporation rates of particles of solid KBr or NH4Cl suspended in argon were studied under high‐temperature conditions behind incident shock waves. The mass‐transfer process during particle evaporation was observed by two optical techniques allowing the measurement of scattered light from a particle ensemble and also from individual particles. The scattered light flux signals were interpreted on the basis of the Mie theory, resulting in values for the time‐dependent particle size and for the refractive index of particle materials. The experiments were performed in the gas‐phase temperature ranges TG = 1070–1300K (KBr) and 525–650K (NH4Cl). The initial size of the suspended particles ranged between 0.6 and 1.0 μm. From the measured decrease in the particle size during the mass‐transfer process the evaporation coefficients of both materials were determined as a function of the gas‐phase temperature. They depend on the vapour pressure and the diffusion coefficient for vapour into gas. Typical parameters (àKBr, m) describing the diffusion coefficient of KBr vapour in argon and the vapour pressure of NH4Cl could be determined.
A Procedure for Blending and Mass Balancing fine particle size data
Authors: Mankosa Michael J. , Adel Greg T.
Published: May 2005

An increased interest in the development of new techniques for fine grinding has resulted in a growing concern over the accuracy of size distributions for extremely fine particles. Since most particle size analyzers have lower detection limits, care must be taken when comparing size distributions which have not been properly mass balanced.

An automated technique has been developed in which a completely mass balanced size distribution can be obtained using an Elzone 80XY particle size analyzer. A computer program is used to blend the data from successively smaller orifice tubes, and to determine the weight percent of material finer than the lower detection limit of the analyzer. This result is then used to correct the distribution for the missing fine material. Experimental results indicate that size distributions obtained using this procedure are reproducible and compare favorably with those obtained using other size analysis techniques.
The Production of Decaborane‐14 from Diborane by Laser Induced Chemistry
Authors: Merritt J. A. , Meyer H. C. , Greenberg R. I. , Tanton G. A.
Published: May 2005

n‐Hexylcarborane (NHC) is the proposed burning rate modifier for improved propellants to be used in the next generation of missiles. The synthesis of this material requires decaborane‐14, a material that is not commercially available in large quantities now. Therefore, the cost‐effectiveness of synthesized NHC, as it relates directly to the missile cost, depends upon a low‐cost synthesis of decaborane‐14. Laser induced chemistry, a revolutionary new kind of chemistry, offers a much more efficient and less expensive way to synthesize compounds than conventional thermochemistry provides. Using this technique, we have synthesized decaborane‐14 from diborane in high yields and high purity using both CO2 and DF laser frequencies. The products are decaborane‐14 formed as white crystals and pentaborane‐9 in the gaseous state; thus, isolation of the decaborane‐14 is a simple chemical engineering procedure.
The Assay of 1‐Ammonium‐3,5‐Dinitro‐1,2,4‐Triazole and its determination in mixtures with ammonium nitrate
Authors: Selig W.
Published: May 2005

Ammonium dinitrotriazole has been assayed by nonaqueous titration as an acid in dimethylsulfoxide versus tetrabutylammonium hydroxide. It can also be assayed by nonaqueous titration as a base in glacial acetic acid versus perchloric acid in glacial acetic acid. In mixtures with ammonium nitrate, ammonium dinitrotriazole can be determined by potentiometric titration in aqueous solution versus cetylpyridinium chloride.
Structure moléculaire des dérivés nitrés aromatiques. I. Etats électroniques singulets du mono et du 1,3,5‐trinitrobenzène
Authors: Boileau J. , Blain M. , Odiot S. , Leclercq J.‐M. , Fliszar S. , Vergoten G. , Fleury C.
Published: May 2005

Les états électroniques singulets du nitrobenzène et du T.N.B. ont été calculés en fonction de la vibration de valence du ou des groupements CNO2, par calcul C.N.D.O/S avec I.C. incluant mono et biexcitations. Le tracé des courbes correspondantes est obtenu ponctuellement à partir du niveau fondamental calculé en S.T.O. 3 G.
Simulation numérique du comportement viscoélastique non‐linéaire d'un materiau explosif
Authors: Belmas R. , Reynaud J. , Sorel J.
Published: May 2005

Nous présentons le principe de deux modèles rhéologiques utilisés dans notre programme de calculs de structures par éléments finis pour décrire le comportement des matériaux agrégataires explosifs.

La viscoélasticité linéaire permet de prendre en compte les phénomènes liés au temps et à la température par l'intermédiaire d'une loi d'équivalence temps‐température ainsi que l'histoire du matériau. La validité de ce modèle est cependant limitée aux domaines de linéarité des matériaux, assez réduits, le plus souvent.

La viscoélasticité non‐linéaire permet de pallier cet inconvénient et de décrire le comportement du matériau depuis l'état de repos jusqu'à la rupture. La non‐linéarité de ce modèle est fondée sur l'utilisation d'une équivalence temps‐pression et temps‐endommagement.

Diverses comparaisons calcul‐expérience viennent confirmer la validité de ce dernier modèle sur toute la gamme d'utilisation du matériau.
On the Behaviour of Nitrate Esters in Acid Solution. II. Hydrolysis and oxidation of nitroglycol and nitroglycerin
Authors: Camera E. , Modena G. , Zotti B.
Published: May 2005

The behaviour of ethylene glycol dinitrate (nitroglycol) and nitroglycerin in moderately concentrated aqueous sulphuric acid, as models of “spent acids”, has been studied. The nitrate esters initial reaction is the simple hydrolysis to yield the alcohols which are eventually oxidized by nitric acid. This reaction, however, is unmeasurably slow in the absence of nitrous acid.
Generation of Free Radicals in RDX and HMX Compositions
Authors: Miles M. H. , Devries K. L. , Britt A. D. , Moniz W. B.
Published: May 2005

Efforts to generate detectable concentrations of free radicals in explosives, binders, and their mixtures are described. Radicals were readily produced in polycaprolactone and polyethylene glycol binders at liquid nitrogen temperature using stresses as low as 0.4 kbar. These radicals were all of the peroxy type, and presumably formed by reaction of mechano‐radicals with oxygen present in the polymer. No mechano‐radicals were observed from HMX or RDX using samples cooled to liquid nitrogen temperature and applied stresses up to 4 kbar. In neither impacted samples that failed to explode nor the residues remaining after a partial explosion were radicals detected by ESR.

Low temperature γ‐irradiation of these materials was also carried out. Free radical signals originating in both the polymer and the explosive could be identified. The reactivity of NO2 radicals from γ‐irradiated HMX is enhanced in the presence of binder. In γ‐irradiated HMX/polycaprolactone mixtures, the NO2 radical anneals rapidly at 150 K, versus 240 K for HMX alone.

Evidence is presented to suggest that the relatively stable NO2 radical (such as produced by γ‐irradiation) in HMX does not play a dominant role in mechanical initiation.
Het powders, Propellants with Controlled Temperature Dependence
Authors: Oversohl W.
Published: May 2005

After a general survey of conventional propellants, there will follow a description of the HET propellants. HET powders are propellants of heterogeneous structure. They are characterized by the powder granules worked into powder basic masses. The powder granules may be grains of single‐base, double‐base or triple‐base propellants. Single‐base powder basic masses are suited to take up a maximum of 70% granules. Granule percentages of about 50% have found to be most efficient. In the case of HET propellants with single‐base matrix, their temperature dependence can be present at discretion, i.e. with neutral of negative temperature exponent, by the type, grain size and percentage of the granules worked in. HET propellants with single‐base powders as basic masses can be produced with explosion heat values of up to 4300 Joule/g. Their manufacture does not present any problems and it is easy from the technical point of view. As full‐strip propellants, the HET types with single‐base powders as basic masses have progressive burning characteristic. HET propellant types are suited also for the manufacture of maccaroni and strip powder. The free‐flowing powder types can be surface coated as usual.
Possibilities for the Detonation of Porous, Fine‐Grained Smokeless powders
Authors: Strnad J. , Gavlas J. , Malkovský K.
Published: May 2005

This article describes a potential cause of detonation in fine‐grained smokeless powders during the production of propelling charges for hunting (lead shot) ammunition, the tests performed in order to deter‐mine this cause, the general possibilities for the deflagration‐to‐detonation transition (DDT) in smokeless nitrocellulose powders, and finally a practical method for determining the predetonation zone with the deflagration of condensed explosives.
Calorimetric Evaluation of Some Variables in Black Powder Making
Authors: Morrow S. I. , Haywood B.
Published: May 2005

Hand‐made, charcoal‐containing black powders exhibited higher heats of combustion than commercial black powders; the values were also higher than values previously reported in the literature. However, commercial pellets attained maximum pressure in a closed bomb upon ignition more rapidly and had better physical integrity than the char‐coal‐containing laboratory products. When channel and furnace blacks were used instead of charcoal, pellets with excellent physical integrity were obtained. These products had lower heats of reaction than commercial black powder and also developed maximum pressure in a closed bomb more slowly. Although adding a small amount of water before or during grinding of mixtures of carbon, sulfur, and potassium nitrate did not affect the heat of reaction of the product significantly, this may have caused the density of some of the products to be abnormally low. Colloidal silica showed promise of being a useful additive in black powder manufacture.
Calculations of Explosion and Detonation Parameters of Explosives
Authors: Niksiński A. , Karczmarewicz A. , Karmiński W.
Published: May 2005

Comparative results of explosive decomposition equation and explosion parameter calculations of several high explosives are described. Calculations were carried out by two different algorithms. Results of calculations are compared with literature data. Some corrections of simple Kamlet's formulae for detonation parameter calculations are proposed adjusting the formulae to calculated explosion parameters.
A Study on Thermodynamic Functions of Detonation Products
Authors: Xiong Wu
Published: May 2005

Thermodynamic parameters of detonation products were calculated using functions based on the enthalpy H0 − H. The results are compared to the experimental data and discussed with respect to other methods. Within the same temperature range the accuracy was considerably improved. The coefficients for the thermodynamic functions of detonation products are given in an appendix.
Preparative and mechanistic studies on unsymmetrical Dimethyl Hydrazine‐Red Fuming Nitric Acid Liquid Propellant Gels
Authors: Munjal N. L. , Gupta B. L. , Varma Mohan
Published: May 2005

Thixotropic gels of unsymmetrical dimethyl hydrazine (UDMH) have been prepared using methyl cellulose (4.48 wt%) and agar‐agar (0.64 wt%) chemical gelling agents. Red fuming nitric acid has been gelled by using sodium silicate (4.25 wt%).

The effect of various parameters like size of container, particle size of gellants and temperature on gellation time of UDMH gelled system has been investigated. The gellation time of UDMH gel is found to increase with the increase in the internal diameter of the container. Gellation time is found to show direct proportionality with the particle size when methyl cellulose is used as gellant. In case of methyl cellulose, the gellation occurs quickly at higher temperature whereas the reverse trend is observed when agar‐agar gellant is used.

In order to boost the performance of liquid propellants, the metallized gels of UDMH containing Al (10‐40 wt%) and Mg (10‐25 wt%) metal powders have been prepared. The density measurements of virgin and metallized gels reveal that there is a maximum gain of 46.72% and 19.3% over virgin gels on incorporation of Al and Mg powders respectively.

Efforts have been made to understand the process of gellation using optical and photomicrographic techniques.
Rheological Studies on Virgin and Metallized Unsymmetrical Dimethyl Hydrazine Gelled Systems
Authors: Gupta B. L. , Varma Mohan , Munjal N. L.
Published: May 2005

Rheological studies on unsymmetrical dimethyl hydrazine‐methyl cellulose gelled system have been conducted under varying shear rates in order to establish its flow characteristics. The gel is found to behave as a pseudoplastic thixotrop. The viscosity build‐up with respect to time has been traced till apparently a firm gel is set. The viscosity is found to increase with time rapidly in the beginning and minor changes are observed thereafter. The effect of temperature and extent of metal (Al and Mg) loading on apparent viscosity of the gelled system has also been investigated. Both the apparent viscosity and thixotropic character of the virgin gel are found to decrease with increase in temperature. An increase in rate of shear decreases the apparent viscosity significantly. The thixotropic character of the metallized gelled systems is observed to increase with metal content and that they exhibit a shearthinning behaviour too. Power law has been applied to assess the variation of pseudoplastic index n and consistency index K with temperature and metallization. The results reveal that n increases with temperature and decreases with metal loading whereas K shows an opposite trend. The yield value of gelled systems is noted to show decrease with temperature and increase with metal incorporation.
Combustion of Energetic Fuel for Ducted Rockets (I)
Authors: Kubota N. , Kuwahara T.
Published: May 2005

Energetic solid fuels composed of modified GAP (glycidyl azide polymer) propellants were formulated in order to obtain optimized combustion characteristics for variable flow ducted rockets. Burning rate in a primary combustor and the combustion efficiency in a secondary combustor were studied and evaluated as a function of the mixture ration of fuel and air. The energetic fuels consisting of – N3 groups in its chemical structure burned very rapidly even though the combustion temperature was low when compared with conventional solid propellants for rockets. The pressure exponent of the burning rate was optimized to gain wide range of mass generation rate. The combustion gases generated in the primary combustor burned very efficiently in a secondary combustor. The effective specific impulse of the ducted rockets was obtained to be about 780 s.
Pressure‐Temperature Phase Diagram of 1,4‐Dinitrocubane
Authors: Piermarini G. J. , Block S. , Iyer S. , Damavarapu R.
Published: May 2005

The pressure‐temperature reaction phase diagram for 1,4‐dinitrocubane (DNC) was determined utilizing optical polarizing microscopy and Fourier transform infrared (FTIR) spectroscopy in conjunction with a high pressure diamond anvil cell and the ruby fluorescence method of pressure measurement. A second‐order structural phase transition from α‐DNC to ß‐DNC has been identified and its pressure dependence determined. The transformation is of an order‐disorder type.
Characterization of plastic‐bonded explosives by pyrolysis gas chromatography and multivariate data analysis part II: Aging studies
Authors: Rietjens M. , Wils E. R. J.
Published: May 2005

Application of Curie point pyrolysis gas chromatography (Py‐GC) and principal component analysis (PCA) in combination with a new normalization method could show the presence of patterns in PCA score plots not visible with the commonly used normalization method. In the first four principal components (PC's), two patterns were observed which could be attributed to aging and the crosslink density (CD). Aging of PBX samples has a complex effect on the peak loadings on PCI and are difficult to reveal. This in contrast to the peak loadings on PC3 and PC4 where both PC's are dominated by only one compound (respectively, C5H6 and cyclohexene). This means that the formation of both these compounds proceeds independently from each other, i.e., by different mechanisms. It was shown that aging is slowed down in samples containing more of the antioxidant Flexzone. From the correlation matrix a few compounds were found to have very high correlations (> 0.98). This was the case for methane, propane and n‐butane in both unaged and aged samples indicating that these compounds do not originate form moieties that are affected by aging. Also, cis‐ and trans‐butene have such high correlations and were formed in a 0.86:1 ratio, probably through the same mechanism. The absolute intensities decrease upon aging suggesting that both compounds originate form those parts of the polymer that are sensitive to aging. PC2 was related to saturated and unsaturated hydrocarbon compounds. The unsaturated compounds result from the elimination of water (free OH groups) from samples with CD values below 1.
Effect of density gradient and porosity on HMX/TNT pressure cast shaped charge performance
Authors: Gharia J. S. , Kumar A. S. , Raghavendra L. N. , Vadali S. R.
Published: May 2005

Precision shaped charges are prepared adopting pressure casting technique. Porosity and voids in such charges which may not be detected by X‐ray radiography would substantially effect the shaped charge performance. The effect of porosity on the parameters like density, VOD, CJ pressure and jet tip velocity have been predicted. Density variation in the charges prepared under different experimental conditions has been determined and compared with that of the predicted values in this paper.
Boron carbide combustion in solid‐fuel ramjets using bypass air. Part I : Experimental investigation
Authors: Natan Benveniste , Netzer David W.
Published: May 2005

The effects of bypass air on the combustion of highly loaded boron carbide/HTPB fuel grains in a solid‐fuel ramjet motor were investigated experimentally. It was found that combustion efficiency can be significantly increased by employing high bypass rations with low dump momentum. The results indicated that high bypass dump momentum causes the particles to collide with the wall and extinguish. Increasing pressure increased efficiency, apparently through the resulting increased residence time. Increased overall equivalence ratio (grain length) also was found to be beneficial, the result of a smaller percentage of larger particles which are generated in the recirculation zone. Some of the reduction in combustion efficiency was determined to be due to incomplete combustion of the HTPB rather than just to the incomplete burning of the boron carbide particles.
Boron carbide combustion in solid‐fuel ramjets using bypass air. Part II: Theoretical analysis
Authors: Natan Benveniste , Netzer David W.
Published: May 2005

The effect of bypass air momentum on the combustion efficiency of a boron‐carbide fueled solid‐fuel ramjet motor has been investigated theoretically. A 3‐D model of the flow in the aft‐burner has been developed and solved numerically. The theoretical results indicated that combustion efficiency can be increased by employing bypass air with low dump momentum, in agreement with experimental results. High bypass air dump momentum was shown to enhance extinguishment of particle combustion through increased collisions with the motor walls.
Sugar derivatives containing oxiranes and α,β‐unsaturated γ‐lactones as potential environmentally friendly insecticides
Authors: Justino Jorge , Rauter Amélia P , Canda Tana , Wilkins Richard , Matthews Elizabeth
Published: May 2005

A range of novel sugar derivatives containing oxiranes or α,β‐unsaturated γ‐lactones in their structure were evaluated as potential insecticides with the added possible benefit of being benign in the environment. A number of arthropod species were chosen to represent those in the terrestrial, aerial and aquatic environments, covering target adult insects such as Musca domestica L (housefly) and Trialeurodes vaporariorum (Westwood) (glasshouse whitefly), which are public health and horticultural pests, Drosophila melanogaster Meig (fruitfly), both adult and larva, and a marine non‐target crustacean, Artemia salina L. The tested compounds possessed efficacy and selectivity against these insect species, but were not toxic to brine shrimps, a reference organism in assays to evaluate the potential toxicity hazard to invertebrates in ecosystems. Copyright © 2005 Society of Chemical Industry
Performance of the reduced‐size polarized Z3PolX basis set in calculations of vibrational polarizabilities, infrared, and Raman intensities: Application to formaldehyde molecule
Authors: Zaleśny Robert , Bartkowiak Wojciech
Published: May 2005

In the present study we report on the results of calculations of pure vibrational polarizability and hyperpolarizability within the double‐harmonic oscillator approximation for the formaldehyde molecule. The results of calculations of the infrared (IR) and Raman intensities are presented as well. The main goal of this investigation was to check the performance of a newly developed reduced‐size polarized Z3PolX basis set. The calculations were performed using the Hartree–Fock (HF) method and the second‐order Møller–Plesset (MP2) perturbation theory with several correlation consistent basis sets. It was found that in the case of formaldehyde, the electron correlation is crucial to reproduce the sign of β. Moreover, the overall performance of the Z3PolX basis set was satisfactory with the enormous reduction of computational time in comparison with correlation consistent basis sets. © 2005 Wiley Periodicals, Inc. Int J Quantum Chem, 2005
Theoretical modeling of the peroxide stretch in H2O2, F2O2, and Fe2O4
Authors: Bacelo Daniel E. , Binning R. C.
Published: May 2005

The structures and harmonic vibrational spectra of H2O2, F2O2, Fe2O4, and Fe2O4(H2O)6 have been examined in theoretical electronic structure calculations. A variety of density functionals and basis sets have been employed to sample the consistency to be expected in calculations on peroxodiiron (III) complexes. It is found that both Gaussian function and numerical basis sets are capable of satisfactory accuracy in determining geometries and vibrational frequencies. Several density functionals fit the experimental vibrational spectra of H2O2 and F2O2 adequately; the BPW91 functional provides the best overall fit. © 2005 Wiley Periodicals, Inc. Int J Quantum Chem, 2005
Improving the efficiency of table‐driven CI
Authors: Harris Frank E.
Published: May 2005

Khait and Hoffmann Int J Quantum Chem 2001, 81, 130 have proposed improvements to the efficiency of the table‐CI method of Buenker and co‐workers for handling spin‐adapted functions in configuration‐interaction studies of open‐shell systems. It is shown that significant further efficiency can be obtained by using methods and formulas published nearly 40 years ago by the present author. © 2005 Wiley Periodicals, Inc. Int J Quantum Chem, 2005
Variational treatment on the energy of the He‐sequence ground state with weakest bound electron potential model theory
Authors: Ma Dong‐Xia , Zheng Neng‐Wu , Fan Jing
Published: May 2005

The concept of spin–orbital of the weakest bound electron is described used to construct the antisymmetric wave function of atomic or ionic systems within weakest bound electron potential model theory (WBEPM theory). The total energies of He‐sequence (Z = 2–9) in the ground states is calculated with a variational method. The effect of fixed orbital approximation is discussed quantitatively. © 2005 Wiley Periodicals, Inc. Int J Quantum Chem, 2005
B3LYP density functional study on spectroscopic properties of CuO− and CuS−
Authors: Midda S. , Bera N. C. , Das A. K.
Published: May 2005

Spectroscopic constant and molecular properties of CuO− and CuS− in their ground state were studied in detail using hybrid the HF/DF B3LYP density functional method. Four basis sets of Cu, one of them fully uncontracted, were used for this calculation. The basis sets for O and S are correlation consistent basis sets. The basis sets were developed systematically in order to see the effect of basis sets on the spectroscopic properties and also to check the consistency of the calculated properties. The B3LYP spectroscopic properties of CuO− agree very well with the only available experimental values. Most of the spectroscopic properties of CuO− and particularly those of CuS− are reported for the first time. © 2005 Wiley Periodicals, Inc. Int J Quantum Chem, 2005
Electronic properties of Strandberg anions: A DFT study of [X2Mo5O23]n−, (X = PV, SVI, AsV, SeVI), and [(RP)2Mo5O21]4− (R = H, CH3, C2H5)
Authors: Yan Li‐Kai , Su Zhong‐Min , Tan Ke , Zhang Min , Qu Lun‐Yu , Wang Rong‐Shun
Published: May 2005

The electronic properties of the anions mentioned in the title polyanions were calculated by means of Density Functional Theory (DFT). The redox properties and the basicity of the external oxygen sites of those polyanions were analyzed. The results show that the redox properties of Strandberg anions depend on the nature of heteroatom X. The organic group bonded to the heteroatom modifies the redox property of the cluster. The oxygen basicities of the polyanions were analyzed by virtue of molecular electrostatic potential (MEP). The MEP distribution suggests that the most basic centers are triple‐bridging oxygen atoms, one of which is shared with two metal atoms and one heteroatom X in [P2Mo5O23]6− and [As2Mo5O23]6−. In [(RP)2Mo5O21]4−, the triple‐bridging oxygen atoms and the double‐bridging oxygen atoms bonded to two Mo atoms identified as the most basic centers. © 2005 Wiley Periodicals, Inc. Int J Quantum Chem, 2005
Theoretical study of helical structure caused by chirality of cysteine dimer
Authors: Liu Shu‐Zhen , Wang Hong‐Qi , Zhou Zheng‐Yu , Dong Xiu‐Li , Gong Xiao‐Li
Published: May 2005

In this work we report a theoretical study of the helix structure and chiral discrimination on the interactions between the chiral cysteine–cysteine. Two reasonable geometries on the potential energy hypersurface of the cysteine–cysteine system are considered with the global minimum. Accurate geometric structures, relative stabilities, harmonic vibrational frequencies, and infrared (IR) intensities were investigated. To take into account the water solvation effect, the Onsager model within the self‐consistent reaction field (SCRF) method and the polarized continuum (PCM) method were used to evaluate the interaction energy, ΔGsolv at the same level employed in the gas phase. The results indicate that the polarity of the solvent plays an important role in the structures and relative stabilities of different isomers. Computational results indicate that the global minimum should be conformer I regardless of whether in the gas phase or in aqueous solution, which differs from previous theoretical reports. © 2005 Wiley Periodicals, Inc. Int J Quantum Chem, 2005
Yuri Alexeev, Theresa L. Windus, Chang‐Guo Zhan, David A. Dixon, Erratum to “Accurate heats of formation and acidities for H3PO4, H2SO4, and H2CO3 from ab initio electronic structure calculations,” International Journal of Quantum Chemistry (2005) 102(5) 775–784
Authors: Alexeev Yuri , Windus Theresa L. , Zhan Chang‐Guo , Dixon David A.
Published: May 2005

The original article to which this Erratum refers was published in International Journal of Quantum Chemistry (2005) 102(5) 775–784
XPS study of ethyl xanthate adsorbed onto cuprous sulphide
Authors: Mielczarski Jerzy , Suoninen Eero
Published: May 2005

Adsorption of xanthate ions from an aqueous solution of potassium ethyl xanthate onto the surface of synthetic polycrystalline chalcocite (Cu2S) samples has been studied by measuring the XPS lines Cu 2p3/2, O 1s, C 1s and S 2p from samples exposed for different times to the xanthate solution. The analysis takes into account the attenuation of the signals, arising from the composition of the sample surface and the orientation of the adsorbed species. The adsorption mechanism is found to consist of a relatively rapid formation of a well‐oriented monolayer of xanthate ions followed by a slow growth of a disordered cuprous xanthate molecules on top of this layer. This mechanism seems to be common for the adsorption of xanthate on many different substrates.
Quantification of preferential sputtering and contamination overlayer effects in AES sputter profiling
Authors: Hofmann S. , Sanz J. M.
Published: May 2005

A model calculation is presented for the quantitative evaluation of AES sputtering profiles of thin layers in the case of preferential sputtering and a contamination overlayer. The model is based on the statistical contribution to depth resolution, the escape depth effect correction and the preferential sputtering model of Ho et al. (1976). Applications to measured AES sputtering profiles of the anodic oxides Ta2O5 and Nb2O5 allow the determination of the thickness and the oxygen content of the contamination overlayer.
Study of the fiber/matrix interface in a SiC reinforced titanium alloy using a high resolution field emission Auger microprobe
Authors: Dudek H. J. , Larson L. A. , Browning R.
Published: May 2005

Using a high‐resolution Auger microprobe the chemical structure of the interface in a SiC reinforced titanium alloy has been examined. Only two phases, TiC and Ti5Si3, are identified in the interface. A TiC layer next to the SiC fiber was proven to form a diffusion barrier for titanium. The results aid in the understanding of the fiber surface degradation process during sample production and suggests processes for the further development of these composites.
Analysis of the Auger KLL spectra of carbon by the pattern recognition method
Authors: Lesiak B. , Mrozek P. , Jabloński A. , Jóźwik A.
Published: May 2005

The carbon KLL spectra were analysed using the pattern recognition methods. The standard spectra were recorded for (i) surface tungsten carbide, (ii) bulk tungsten carbide, (iii) graphite and (iv) amorphous carbon. The set of these spectra was a basis for the process of recognition. The careful analysis of the set of standard spectra made possible construction of several procedures (classifiers) for recognizing the chemical form of carbon corresponding to a given spectrum. The KLL spectra of carbonaceous residue growing on nickel foil were analysed using all the developed classifiers. At the early stages of growth the carbidic form of carbon was recognized, followed by the graphitic form at further stages. This result agrees with observations reported in the literature.
Distribution analysis of carbon and sulphur in CVD‐Al2O3‐layers by SIMS using Cs+ primary ions
Authors: Wilhartitz P. , Grasserbauer M. , Altena H. , Lux B.
Published: May 2005

Secondary ion mass spectrometry was used to determine the carbon and sulphur content of aluminium oxide layers. Information about the lateral distribution was gained using ion imaging. For the characterization of the depth distribution, sputter profiling with high mass resolution was applied. Carbon was found to form a network structure within the aluminium oxide layer but carbides could not be detected. Evaluation of atomic and molecular ion patterns were used for speciation of carbon. Practical sensitivity factors were determined and used for semiquantitative evaluation of the depth profiles. The sputter rate of aluminium oxide and the ionisation probabilities of oxygen and aluminium were calculated.
Effects of the alloying elements Ti, Nb, Mo and V on the grain boundary segregation of P in iron and steels
Authors: Grabke H. J. , Möller R. , Erhart H. , Brenner S. S.
Published: May 2005

Investigations have been performed on the effects of the alloying elements Ti, Nb, Mo and V on the grain boundary segregation of phosphorous in iron and steels. The methods are AES analysis of grain boundaries on intergranular fracture faces and field‐ion microscopy and mass spectrometry (atomprobe). The elements Ti and Nb show strong interaction with P, keeping P in the grain and decreasing its grain boundary segregation. In the alloys and steels containing carbon, Ti and Nb react under formation of carbides, therefore with increasing C content the grain boundary segregation of P increases. For stoichiometric ratio Ti/C and Nb/C the segregation reaches a maximum; at higher carbon contents C displaces P from the grain boundaries. Some interfacial segregation of P is observed at or near the ferrite/carbide interface in the case of TiC, leading to a decrease of grain boundary segregation. The same effect applies for Mo2C but not for NbC. In contrast to Ti and Nb there is no direct interaction of Mo and P, which is also in contradiction to previous assumptions on the role of molybdenum in the temper embrittlement of low alloy steels.