Synthesis of Dimethyl Carbonate from CO2 , Methanol, and Epoxides Using Re（CO） 5 Cl/K2 CO3 as Catalyst System

IntroductionOver the past few years, dimethyl carbonate(DMC) has been proven to be an efficientmethylating,methoxylating, and methoxycarbonylating agent inorganic syntheses, in which DMC is used to replace thetoxic methyl halides, dimethyl sulfate or carb     

Simulation and fabrication of carbon nanotubes field emission pressure sensors

A novel field emission pressure sensor has been achieved utilizing carbon nanotubes (CNTs) as the electron source. The sensor consists of the anode sensing film fabricated by wet etching process and multi-wall carbon nanotubes (MWNTs) cathode in the micro-vacuum chamber. MWNTs on the silicon substrate were grown by thermal CVD. The prototype pressure sensor has a measured sensitivity of about 0.17-0.77 nA/Pa (101-550 KPa). The work shows the potential use of CNTs-based field-emitter in microsensors, such as accelerometers and tactile sensors.     

新疆野生黑加仑与马林果实的营养成分分析

通过对新疆野生黑加仑和野生马林的脂肪油，8种微量元素，17种氨基酸以及维生素C的含量进行测定得出：黑加仑脂肪油含量为17．9％，马林的脂肪油含量为22．3％，其中，黑加仑脂肪油中，r－亚麻酸的含量为19．02％，而马林中，其含量为9．40％，黑加仑中K，Na,Ca,Cu,Zn,Fe的含量比马林中的含量高，而Mn,Mg元素的含量却比马林含量低；马林的维生素C含量为16．22mg/g，黑加仑的含量为108mg/g，黑加仑的氨基酸的总量为1．63％，马林为1．14％。     

MORPHOLOGY OF BLACK CARBON AEROSOLS AND UBIQUITY OF 50-NANOMETER BLACK CARBON AEROSOLS IN THE ATMOSPHERE

Different-sized aerosols were collected by an Andersen air sampler to observe the detailed morphology of the black carbon （BC） aerosols which were separated chemically from the other accompanying aerosols, using a Scanning Electron Microscope equipped with an Energy Dispersive X-ray Spectrometer （SEM-EDX）. The results indicate that most BC aerosols are spherical particles of about 50 nm in diameter and with a homogeneous surface. Results also show that these particles aggregate with other aerosols or with themselves to form larger agglomerates in the micrometer range. The shape of these 50-nm BC spherical particles was found to be very similar to that of BC particles released from petroleum-powered vehicular internal combustion engines. These spherical BC particles were shown to be different from the previously reported fullerenes found using Matrix-Assisted Laser Desorption/Ionization Time-Of-Flight Mass Spectrometry （MALDI-TOF-MS）.     

Peculiar relics from Primordial Black Holes in the inflationary paradigm

Depending on various assumptions on the energy scale of inflation and assuming a primordial power spectrum of a step‐like structure, we explore new possibilities for Primordial Black Holes (PBH) and Planck relics to contribute substantially to Cold Dark Matter in the Universe. A recently proposed possibility to produce Planck relics in four‐dimensional string gravity is considered in this framework. Possible experimental detection of PBHs through gravitational waves is also explored. We stress that inflation with a low energy scale, and also possibly when Planck relics are produced, leads unavoidably to relics originating from PBHs that are not effectively classical during their formation, rendering the usual formalism inadequate for them.     

电磁学黑匣子实验的设计与解答Ⅱ--奥林匹克物理竞赛培训试题二

介绍了一个电磁学黑匣子实验，对其作了具体的解答，并提供多种解决方案，且指出了此题的特点和实验过程中可能出现的问题．     

Hawking Radiation of Dirac Particles in a Nonuniformly Rectilinearly Accelerating Black Hole

The Hawking radiation of Dirac particles on the event horizon of a nonuniformly rectilinearly accelerating black hole is studied in this paper. First, we construct the symmetrized null tetrad from which the spin coefficients and Dirac equation are derived. Next, by proposing generalized tortoise coordinate transformation, the decoupling problem of the Dirac equation with nonzero rest mass is solved. Finally, by analytic continuation, the Hawking thermal spectrum formula of Dirac particle for nonuniformly rectilinearly accelerating black hole is obtained.     

二氧化碳和丙烯直接合成甲基丙烯酸的NiPMo/TiO2催化剂的研究

用溶胶 凝胶法以磷钼酸 (MPA)的镍盐溶液水解钛酸四丁酯制备了NiPMo/TiO2 催化剂 .使用ICP、XRD、TG DTA、IR、TPD MS和微反应技术研究了催化剂的化学组成、热稳定性、化学吸附性质和催化反应性能 .杂多钼酸盐与TiO2 通过O2 -在TiO2 表面发生了键合 .在 6 2 3K下 ,杂多阴离子仍保持原有的Keggin结构 .CO2 在Lewis酸位Ni(Ⅱ )和Lewis碱位Ni-O -Mo的桥氧协同作用下生成CO2 卧式吸附态Ni(Ⅱ )←O - (CO)← (O--Ni) .丙烯有多种吸附态在催化剂上吸附 .在 5 6 3K、1MPa和空速 15 0 0h-1的反应条件下 ,丙烯的摩尔转化率为 3.2 % ,产物MAA选择性为 95 % .     

Tunneling radiation of a Gibbons-Maeda dilaton black hole

We use the Parikh-Wilczek method to treat Hawking radiation as a tunneling process across the event horizon and calculate the emission rate of a Gibbons-Maeda dilaton black hole. We show that if self-gravitation is taken into account, then the radiation deviates from the purely thermal spectrum, and the corrected spectrum is consistent with an underlying unitary theory. __________ Translated from Teoreticheskaya i Matematicheskaya Fizika, Vol. 151, No. 1, pp. 172–175, April, 2007.     

Quantum Thermal Effect of Dirac Particles in a Nonuniformly Rectilinearly Accelerating Black Hole with Electric Charge, Magnetic Charge, and Cosmological Constant

The Hawking radiation of Dirac particles in an arbitrarily rectilinearly accelerating Kinnersley black hole with electromagnetic charge and cosmological constant is investigated by using the generalized tortoise coordinate transformation. Both the location and the temperature of the event horizon depend on the time and the polar angle. The Hawking thermal radiation spectrum of Dirac particles is also derived.