The influence of dissociation reaction on ammonium nitrate thermal decomposition reaction

In order to investigate the influence of dissociation reaction on thermal decomposition of ammonium nitrate (AN), biochar was selected as an adsorbent to interfere with the dissociation of AN. The TG-DSC results showed that the notable exothermic reaction of AN with the presence of 2% or 7% biochar took place. The decomposition temperature of AN decreased with increasing amount of biochar. The notable knee point was found in the TG curves. The activation energy of AN with biochar in the initial stage was higher than that of AN itself. Remote sensing Fourier transform infrared experiments found biochar induced AN decomposition at about 190 °C, which was also confirmed by the TG-MS results. After dissociation reaction, HNO₃ (g) and NH₃ (g) were adsorbed and crystalline of AN was formed on the surface of biochar. With the increasing temperature, NH₃ escaped from the surface of biochar, while HNO₃ (g) was stayed in biochar. HNO₃ (g) catalyzed the thermal decomposition of AN and also reacted with biochar. The results indicated that dissociation reaction of AN played an important role during AN thermal decomposition process. When dissociation reaction was changed, the thermal decomposition reaction of AN would also change, catalysis or inhibition AN thermal decomposition. It is a useful reference to guide the AN additives selection and to understand the mechanism for the AN decomposition accident.

     

Temperature- and Pressure-induced Structural Transition of Binary Clathrate Hydrates

We discover new structure II (sII) hydrate forming agents of two C₄H₈O molecules (2-methyl-2-propen-1-ol and 2-butanone) and report the abnormal structural transition of binary C₄H₈O+CH₄ hydrates between structure I (sI) and sII with varying temperature and pressure conditions. In both (2-methyl-2-propen-1-ol+CH₄) and (2-butanone+CH₄) systems, the phase boundary of the two different hydrate phases (sI and sII) exists at the slope change of the phase-equilibrium curve in the semi-logarithmic plots. We confirm the crystal structures of two hydrates synthesized at low (278 K and 6 MPa) and high (286 K and 15 MPa) temperature and pressure conditions by using high-resolution powder diffraction and Raman spectroscopy. 2-Methyl-2-propen-1-ol and 2-butanone can occupy the large cages of sII hydrate at low temperature and pressure conditions; however, they are excluded from the hydrate phase at high temperature and pressure conditions, resulting in the formation of pure sI CH₄ hydrate.     

单氯化锶分子低激发态的光谱及跃迁特性

利用Davidson修正的内收缩多参考组态相互作用(ic-MRCI+Q)方法,结合相对论有效芯赝势基(augcc-pV5Z-PP)作为Sr原子和相关一致五重基aug-cc-pV5Z为Cl原子的计算基组,优化计算了单氯化锶(Sr~(35)Cl)分子14个低激发电子态的势能曲线和跃迁偶极矩.为了获得更加精确的光谱参数,计算中同时引入核价电子相关和相对论效应修正势能曲线.利用LEVEL 8.0程序拟合修正的势能曲线,得到相应电子态的光谱常数、振动能级和分子常数等光谱性质,结果与近来的已获得的理论计算和实验值符合得较好,同时给出了Franck-Condon因子和辐射寿命等跃迁性质.这些精确的光谱跃迁特性可为进一步构建Sr~(35)Cl分子激光冷却方案提供理论支持.     

Particle size dependence of electro-optical switching in ZrP nano colloid

Aqueous colloid of 2-dimensional (2D) α-ZrP nanoparticles can serve as an excellent material for Kerr devices. We investigate the influence of the particle size on the electro-optical switching for isotropic and biphasic α-ZrP colloids that exhibit stable Kerr effect. Smaller sized α-ZrP colloid has wider range of isotropic and biphasic phases, but since the anisotropic polarizability is approximately proportional to square diameter of particles, the larger sized α-ZrP colloid has higher birefringence at a given concentration. The dynamic response time is also dramatically influenced by the particle size. Smaller sized particle has lower viscosity, and the fall time monotonically increases with increasing particle size. However, the rise time has the minimum at around 0.6 μm owing to the competitive contributions of the anisotropic polarizability and the rotational viscosity. Thus, the particle size in α-ZrP colloid is an important factor to determine the electro-optical performance of a Kerr device based on 2D α-ZrP colloids. These findings will be important in developing electro-optical devices using lyotropic liquid crystal colloids.     

Effect of organosilane agents on the vulcanizate structure and physical properties of silica-filled solution styrene butadiene rubber compounds

Physical properties of rubber compounds are affected by the filler-rubber interaction, filler dispersion in the rubber matrix, and crosslink structure formed during vulcanization. Organosilane agents are essentially used in silica-rubber compounds to inhibit the formation of silica agglomerates and increase the formation of silica-rubber networks. Generally, organosilane agents have an alkoxysilyl alkyl sulfide structure and are classified into silane coupling and covering agents depending upon the presence of sulfur. Coupling agents have a sulfur moiety and serve as a sulfur donor during the vulcanization process, thus increasing the formation of filler-rubber and chemical crosslink networks. On the other hand, covering agents promote the hydrophobation of silica surfaces, decreasing the adsorption loss of vulcanization additives, which increases the formation of chemical crosslink networks. This implies that organosilane agents can affect the vulcanizate structure, which causes a variation in the properties of silica compounds. Therefore, in this study, the effect of coupling (bis(3-triethoxysilylpropyl)disulfide (TESPD) and bis(3-triethoxysilylpropyl)tetrasulfide (TESPT)) agents and a covering (triethoxy(octyl)silane) agent on the vulcanizate structure and properties of silica compounds was investigated and compared. In the comparative study of coupling and covering agents, the influence of sulfur donors on the formation of vulcanizate structures was investigated. In the case of the coupling agents, the effect of sulfur rank on the vulcanizate structure and properties of silica-rubber compounds was quantitatively analyzed through various characterization techniques.     

Devices and architectures for photonic chip-scale integration

Silicon nanophotonics holds the promise of dramatically advancing the state of the art in computing by enabling parallel architectures that combine unprecedented performance and ease of use with affordable power consumption. This paper presents a design study for a many-core architecture called Corona which utilizes dense wavelength division multiplexing (DWDM) for on- and off-chip communication together with the devices which will be needed to implement such a communication infrastructure.     

部分相干厄米-双曲正弦-高斯光束通过湍流大气传输的平均光强分布演化和角扩展

推导出部分相干厄米-双曲正弦-高斯(H-ShG)光束通过湍流大气的平均光强和角扩展的解析表示式,并用以研究了部分相干H-ShG光束在湍流中的平均光强分布演化和角扩展. 结果表明,折射率结构常数C²_n的增加和空间相关长度σ₀的减小都会加速演化过程. 引入相对角扩展来定量描述光束抗拒湍流的能力. 空间相关长度σ₀,束腰宽度w₀和双曲 关键词： 平均光强分布演化 角扩展 湍流大气 部分相干厄米-双曲正弦-高斯(H-ShG)光束     

Phase Behavior of a Weakly Interacting Polystyrene and Poly(n‐hexyl methacrylate) System: Evidence for the Coexistence of UCST and LCST

The phase behavior of a weakly interacting binary system composed of deuterated polystyrene (dPS) and poly(n‐hexyl methacrylate) (PnHMA) was investigated by the turbidity measurement for the binary blend, and by small angle X‐ray scattering (SAXS) and depolarized light scattering for the block copolymers. For the binary dPS/PnHMA blend, a new phase diagram involving both the upper critical solution transition (UCST) and lower critical solution transition (LCST) was observed by the delicate control of molecular weights between dPS and PnHMA. Whereas for the block copolymers such as dPS‐block‐PnHMA and PS‐block‐PnHMA, an order‐to‐disorder transition (ODT) on heating was observed within the experimental temperature range depending on the molecular weight. This coexistence of both a UCST and LCST in the dPS/PnHMA blend consequently represents the experimental evidence that the corresponding (d)PS‐b‐PnHMAs possess not only ODT, but also lower disorder‐to‐order transition (LDOT) character driven by a compressibility difference, although the latter is hindered by thermal degradation.

     

Measurement of the inclusive jet cross section in pp[over] collisions at square root [s]=1.96 TeV

We report on a measurement of the inclusive jet cross section in pp[over ] collisions at a center-of-mass energy sqrt[s]=1.96 TeV using data collected by the D0 experiment at the Fermilab Tevatron Collider corresponding to an integrated luminosity of 0.70 fb;{-1}. The data cover jet transverse momenta from 50 to 600 GeV and jet rapidities in the range -2.4 to 2.4. Detailed studies of correlations between systematic uncertainties in transverse momentum and rapidity are presented, and the cross section measurements are found to be in good agreement with next-to-leading order QCD calculations.     

Search for flavor-changing-neutral-current d meson decays

We study the flavor-changing-neutral-current process c-->u micro(+) micro(-) using 1.3 fb(-1) of pp[over ] collisions at square root s = 1.96 TeV recorded by the D0 detector operating at the Fermilab Tevatron Collider. We see clear indications of the charged-current mediated D(s)(+) and D(+)-->phipi(+) --> micro(+)micro(-)pi(+) final states with significance greater than 4 standard deviations above background for the D(+) state. We search for the continuum neutral-current decay of D(+)-->pi(+) micro(+) micro(-) in the dimuon invariant mass spectrum away from the phi resonance. We see no evidence of signal above background and set a limit of B(D(+) --> pi(+) micro(+) micro(-))<3.9 x 10(-6) at the 90% C.L. This limit places the most stringent constraint on new phenomena in the c--> u micro(+) micro(-) transition.