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1.
Marcos A. Kettner Prof. Dr. Konstantin Karaghiosoff Prof. Dr. Thomas M. Klapötke Dr. Muhamed Sućeska Swetlana Wunder 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(25):7622-7631
Here we report on the preparation of two hydrogen atom free 3,3′‐bi(1,2,4‐oxadiazole) derivatives. 5,5′‐Bis(fluorodinitromethyl)‐3,3′‐bi(1,2,4‐oxadiazole) was synthesised by fluorination of diammonium 5,5′‐bis(dinitromethanide)‐3,3′‐bi(1,2,4‐oxadiazole). For our previously reported analogue 5,5′‐bis(trinitromethyl)‐3,3′‐bi(1,2,4‐oxadiazole), a new synthetic route starting from new 3,3′‐bi(1,2,4‐oxadiazolyl)‐5,5′‐diacetic acid was developed. In this course also hitherto unknown 5,5′‐dimethyl‐3,3′‐bi(1,2,4‐oxadiazole) was isolated. The compounds were characterised by multinuclear NMR spectroscopy, IR and Raman spectroscopy, elemental analysis as well as mass spectrometry. X‐ray diffraction studies were performed and the crystal structures for the 5,5'‐dimethyl and 5,5'‐(fluorodinitromethyl) derivatives are reported. The energetic 5,5'‐(fluorodinitromethyl) and 5,5'‐(trinitromethyl) compounds do not contain any hydrogen atoms and show remarkable high densities. Furthermore, the thermal stabilities and sensitivities were determined by differential scanning calorimetry (DSC) and standardised impact and friction tests. The heats of formation were calculated by the atomisation method based on CBS‐4M enthalpies. With these values and the room‐temperature X‐ray densities, several detonation and propulsion parameters, such as the detonation velocity and pressure as well as the specific impulse of mixtures with aluminium, were computed using the EXPLO5 code. 相似文献
2.
This research was supported by Republička Zajednica Nauke BiH. 相似文献
3.
Muhamed Borogovac 《Journal of Difference Equations and Applications》2016,22(6):727-744
In the first part of the article, a new interesting system of difference equations is introduced. It is developed for re-rating purposes in general insurance. A nonlinear transformation φ of a d-dimensional (d ≥ 2) Euclidean space is introduced that enables us to express the system in the form ft+1:=φ( ft), t = 0, 1, 2,. …. Under typical actuarial assumptions, existence of solutions of that system is proven by means of Brouwer’s fixed point theorem in normed spaces. In addition, conditions that guarantee uniqueness of a solution are given. The second, smaller part of the article is about Leslie–Gower’s system of d ≥ 2 difference equations. We focus on the system that satisfies conditions consistent with weak inter-specific competition. We prove existence and uniqueness of the equilibrium of the model under surprisingly simple and very general conditions. Even though the two parts of this article have applications in two different sciences, they are connected with similar mathematics, in particular by our use of Brouwer’s fixed point theorem. 相似文献
4.
Adsorption of I2 by Macrocyclic Polyazadithiophenolato Complexes Mediated by Charge‐Transfer Interactions
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Matthias Golecki Norman Beyer Dr. Gunther Steinfeld Dr. Vasile Lozan Dr. Sergei Voitekhovich Dr. Muhamed Sehabi Dr. Jens Möllmer Prof. Dr. Hans‐Jörg Krüger Prof. Dr. Berthold Kersting 《Angewandte Chemie (International ed. in English)》2014,53(37):9949-9952
The macrocyclic complex [Ni2(L)(OAc)]ClO4 ( 1 ) adsorbs up to 17 molar equivalents (>270 wt %) of iodine, although it does not exhibit permanent porosity. Vibrational spectroscopic and crystallographic studies reveal that two I2 molecules are captured by means of thiophenolate→I2 charge‐transfer interactions, which enable the diffusion and sorption of further I2 molecules in a polyiodide‐like network. The efficient sorption and desorption characteristics make this material suitable for accommodation, sensing, and slow release of I2. 相似文献
5.
New polynitro compounds containing a carbonyl biscarbamate moiety derived from the precursor carbonyldiisocyanate were synthesized. In addition, 2, 2‐dinitropropane‐1, 3‐diyl bis(2, 2,2‐trinitroethylcarbamate) and 2, 2‐dinitropropane‐1, 3‐diyl bis(2, 2,2‐trinitroethyl) dicarbonate, were synthesized using 2, 2‐dinitropropane‐1, 3‐diol as starting material. The compounds were characterized by using the analytical methods, single‐crystal X‐ray diffraction, vibrational spectroscopy (IR and Raman), multinuclear NMR spectroscopy, elemental analysis, and mass spectrometry. The thermal behavior was investigated with DSC measurements. The suitability of the compounds as potential oxidizers in energetic formulations was determined. The heats of formation of the compounds were calculated with GAUSSIAN 09. The detonation parameters such as the detonation pressure, velocity, energy, and temperature were computed using the EXPLO5 code. For a secure handling of the materials, the sensitivity towards impact, friction, and electrical discharge was tested using the BAM drop hammer, BAM friction tester as well as a small‐scale electrical discharge device, respectively. 相似文献
6.
In [2] we characterized the class of matrices with nonnegative principla minors for which the linear-complementarity problem
always has a solution. That class is contained in the one we study here. Our main result gives a finitely testable set of
necessary and sufficient conditions under which a matrix with nonnegative principal minors has the property that if a corresponding
linear complementarity problem is feasible then it is solvable. In short, we constructively characterize the matrix class
known asQ
o
∩P
o
.
Research partially supported by the National Science Foundation Grant DMS-8420623 and U.S. Department of Energy Contract DE-AA03-76SF00326,
PA # DE-AS03-76ER72018. 相似文献
7.
This paper concerns three classes of matrices that are relevant to the linear complementarity problem. We prove that within the class ofP
0-matrices, theQ-matrices are precisely the regular matrices.Research supported by Department of Energy, Contract EY-76-S-03-0326 PA # 18. 相似文献
8.
Cerium oxide (CeO2) is a potential corrosion inhibitor for aluminium, and titanium oxide (TiO2) is an efficient anti-fouling agent in the marine environment. The present study explored the possibility of incorporating
CeO2 and TiO2 in aluminium to prepare a metal matrix composite that could have high corrosion and biofouling resistance under marine conditions.
Such incorporation of CeO2 and TiO2 in pure aluminium offered high resistance to corrosion and biogrowth under marine conditions as evidenced during different
tests. The specimens exhibited more anodic and stable open circuit potential throughout the period of the study. The optimum
concentration of CeO2 and TiO2 was found to be 0.2 and 0.1%, respectively. The present results lay emphasis on the potential scope of the use of CeO2- and TiO2-incorporated aluminium in marine environments. 相似文献
9.
Muhamed Sućeska Zhi-Yue Liu Sanja Matečić Mušanić Ivona Fiamengo 《Journal of Thermal Analysis and Calorimetry》2010,100(1):337-345
Due to dynamic nature of processes taking place during the experiment (chemical reaction and physical processes, heat flow,
gas flow, etc.) the results obtained by thermal methods may considerably depend on the conditions used during the experiment.
Therefore, whenever the results of thermal analysis are reported, the experimental conditions used should be stated. In this
paper we have studied the heat transfer from the furnace to the sample and through the sample during dynamic mechanical analysis
measurements. Numerical modelling of the heat transfer was done using an own computer program based on the heat conduction
equation, solved numerically applying the finite difference methods. The calculated values of the thermal lag between the
furnace and the sample were compared with the values experimentally determined on samples of a composite polymeric energetic
material (double-base rocket propellant). Also, the temperature distribution within the sample as a function of the heating
rate was analysed using the same numerical model. It was found out that using this model and temperature dependent heat transfer
coefficient, experimentally obtained values of the thermal lag between the furnace and the sample can be satisfactory described.
It was also shown that even at slow heating rates, such is, e.g. 2 °C min−1, the thermal lag between the furnace and the sample can reach several degrees, while the thermal gradient within 3-mm thick
rectangular sample can reach 0.4 °C. 相似文献
10.
The presence of surfactants (Hexamine, tetraethylammonium bromide (TEAB), cetyltrimethylammonium bromide (CTAB), tetraoctylammonium bromide (TOAB) and PVP) on the surface of zinc oxide (ZnO) nanoparticles resulted variation in their optical properties. The optical properties of each surfactant-capped zinc oxide nanoparticles were investigated using UV-visible absorption and fluorescence techniques. The particle size of these nanoparticles were calculated from their absorption edge, and found to be in the quantum confinement range. The absorption spectra and fluorescent emission spectra showed a significant blue shift compared to that of the bulk zinc oxide. Large reduction in the intensity of visible emission of zinc oxide/surfactant was observed and these emissions were vanished more quickly, with the decrease in excitation energy, for the smaller nanoparticles. Out of the four surfactants (other than PVP), CTAB-capped zinc oxide has smallest particle size of 2.4 nm, as calculated from the absorption spectrum. Thus the presence of surfactant on the surface of zinc oxide plays a significant role in reducing defect emissions. Furthermore, ZnO/PVP nanoparticles showed no separate UV emission peak; however, the excitonic UV emission and the visible emission at 420 nm overlap to form a single broad band around 420 nm. 相似文献