Thermodynamic considerations regarding the matrix stability of MLncomplexes (where L = CO or N2)

Some thermodynamic considerations affecting the stability of matrix isolated molecules of the type ML_n formed in metal atom (M)-ligand(L) cocondensation reactions are discussed. It is found that because of the large heat of sublimation of most metals, compounds of the above type will be unusually stable in the matrix. An empirical relation between the MC and MN bond energies and the decrease in the corresponding ligand bond stretching force constant is introduced and applied to estimating the MC bond energy in Pd(CO)₄ and Pt(CO)₄.     

雾化角对液体火箭发动机燃烧室压力振荡的影响

针对液氧/煤油火箭发动机模型燃烧室实现了三维非稳态两相燃烧过程的数值模拟,得到的燃烧室截面平均压力和平均速度与实验吻合。在初边值条件不施加任何扰动的情况下,得到了燃烧室压力自激振荡过程,并研究了液氧和煤油喷嘴雾化角对燃烧室压力振荡的影响。计算结果表明:当雾化角为40°或120°时,由于燃料与氧化剂喷雾锥重叠区域较小或较大,导致了推进剂混合很差或很好,不易在燃烧室头部出现局部爆炸性的可燃混气团,致使燃烧室压力振荡强度较弱;而当雾化角为中间值65°时,易于出现爆炸性的可燃气团并导致剧烈的压力振荡,使燃烧室中出现燃烧不稳定性。因此,雾化角的合理设计是抑制燃烧不稳定性的一种途径。     

内蒙古地区沙生植物--沙枣中维生素C含量的测定

在 pH 6.0的 HAc-NaAc缓冲溶液中,用活性炭吸附沙枣中的色素,Cu(Ⅱ)催化氧化维生素C,在λmax=268 nm处可直接测定沙枣中维生素C含量.与传统碘量法相比,测定结果基本一致.为内蒙古地区沙枣天然植物资源的药用开发、食品加工等提供了参考数据.     

Laser Diode-Pumped Nd：LuVO4 Acousto-Optic Q-Switched Laser at 916 nm

A compact laser diode-pumped solid-state Nd：LuVO4 acousto-optic Q-switched laser is demonstrated at 916 nm of a quasi-three level for the first time. A pulse width of 130ns is observed when the pulse-repetition frequency is 10 kHz. The laser experiment shows that the Nd：Lu VO4 crystal can be used for efficient diode-pumped Q-switched lasers.     

Anchoring BaII to Pd/HyWO3−x Nanowires Promotes a Photocatalytic Reverse Water–Gas Shift Reaction

Surface deposition of Ba^II on Pd/H_yWO_3−x nanowires was developed by using a solution-phase atomic layer deposition process. The procedure involves the generation of Brønsted surface OH sites by H₂ spillover on Pd/WO₃, which can then hydrolytically condense with Ba(OEt)₂ to produce surface Ba^II. At just 0.2 at % Ba, CO production by the light-assisted activity of the reverse water–gas shift (RWGS) reaction was observed to increase by about 300 %. In situ DRIFTS studies suggested enhanced CO₂ capturing capabilities of a Ba-decorated surface. This study further exemplifies the importance of surface chemistry in optimizing materials for catalysis.     

Periodic mesoporous phenylenesilicas with ether or sulfide hinge groups--a new class of PMOs with ligand channels

A new class of periodic mesoporous organosilicas (PMOs) with 4-phenyl ether and 4-phenyl sulfide bridge-bonded silsesquioxanes integrated into the pore walls to create ligand channels have been synthesized using inorganic salt-assisted self-assembly directed by a supramolecular polyoxyethylene (10) stearyl ether (Brij 76) template.     

Towards flexible inorganic "mesomaterials": one-pot low temperature synthesis of mesostructured nanocrystalline titania

We hereby report a simple route for the low temperature synthesis of mesoporous nanocrystalline titania involving brief hydrothermal treatment of butanolic precursors and non-ionic tri-block-copolymer surfactant at 100 degrees C, followed by evaporation induced self assembly to make a crack-free flexible film. At no time in the film-forming process is a temperature of more than 120 degrees C reached, thereby permitting the use of substrates that are not stable to higher temperatures.