Spherical Particles of Zirconia-Titania of Hexagonal Structure from a Neutral Amine Route

Through the sol–gel process, using the so-called neutral amine route, spherical particles of 1:1 zirconia–titania were synthesized from zirconium(IV) and titanium(IV) butoxides as well as 1,12-diaminododecane as precursor species. The obtained product exhibited a hexagonal structure, as determinated by X-ray diffraction data. The obtained material was also characterized by thermogravimetry, differential scanning calorimetry, infrared spectroscopy, scanning electron microscopy, and surface area measurements. Despite the release of template molecules on heating, the spherical morphology was retained up to about 1200°C, at which the disruption of the spheres took place.     

Gravitational waves and red shifts: A space experiment for testing relativistic gravity using multiple time-correlated radio signals

We describe an experimental technique for detecting extremely low-frequency pulses of gravitational radiation ( _GW 1–10 mHz) originating from collapsing supermassive objects (M 10⁶–10⁷ m ) occurring anywhere in the universe. Our technique is the natural outgrowth of a previous gravitational space mission. The novelty of our approach is in placing a highly stable hydrogen maser onboard a deep-space probe that controls a transmitter sending signals to earth. The spacecraft also includes a doppler transponder operating in the conventional two-way mode. Doppler tracking using simultaneously acquired one- and two-way information both on the spacecraft and at the earth station provides four time-records of frequency fluctuations. A single gravitational disturbance manifests itself as a uniquely determined pulse sequence in the two or more data sets whose amplitudes and arrival times depend on a single parameter. The repetition of the signal and the noises in the data can be used in a filtering scheme to improve the amplitude sensitivity by a factor of about 6 in amplitude (36 in energy). We believe the most likely of these gravitational pulse events occurring frequently enough to be detected (more than once per year) will come from the formation of black holes in the cores of ordinary spiral galaxies. We propose a technologically feasible and realistic space mission, using the above technique, to measure two aspects of gravitation with the same experimental equipment. The spaceflight begins in a highly eccentric earth orbit to measure the gravitational red shift and the second-order doppler effects to an accuracy of 5 parts in 10⁶; at this level significant new tests of nonmetric theories of gravity are possible. Later, the spacecraft is sent into a heliocentric orbit to distances beyond 6 AU to search for gravitational radiation.     

Effects of Adsorbed Polyaniline on Redox Process on MoO3 Surface

The effects exhibited by adsorbed conducting polyaniline on the redox process on a molybdenum oxide surface were studied. Thermogravimetric results indicate a 4% polyaniline deposition. Cyclic voltammograms of the adsorbed polymer on MoO3 show that polyaniline exerts remarkable effects on the molybdenum blue oxidation-reduction process, with oxidation and reduction potentials of 0.33 and 0.18 V, respectively. This effect strongly enhances the electrode response, and can be used as an important tool in qualitative and/or quantitative determinations of molybdenum in solution as well as in any substrate. Copyright 1999 Academic Press.     

The second-order gravitational redshift

It now appears possible that anotherdistinct test of the second-order term of general relativity may be feasible, through the use of very stable atomic clocks. This experiment, which would measure the second-ordergravitational redshift, is a bona fidetest of the field equations of gravity, not just a test of the underlying principle of equivalence.Presented at the Seventh International Conference on Gravitation and Relativity, June 1974, Tel-Aviv, IsraelResearch supported in part by NASA Research Grant NGR 09-015-205.     

HL-2M 装置电子回旋共振加热及电流驱动系统设计与研制进展

根据 HL-2M 装置物理实验加热的需求,完成了总功率为 8MW 的电子回旋共振加热及电流驱动 (ECRH/ECCD)系统设计,开展了波源、传输及天线等关键部件研制。8MW ECRH/ECCD 系统,由 8 套 105GHz/  1MW/3s 波源系统、8 条内径为 63.5mm 的真空传输线及三套极向实时可控的发射天线构成。目前,已完成 ECRH/ECCD 系统关键部件研制及其相关的桌面与高功率性能测试。测试结果表明,微波源回旋管输出微波功率 达到1MW/3s,在真空度为 10^‒2Pa 的过模波纹圆波导传输线中能低耗稳定传输,发射天线极向全量程角度转动响 应时间在 50ms 以内。      

A test of the equivalence principle using a space-borne clock

An experimental verification of Einstein's equivalence principle has been made using an atomic hydrogen maser in a space probe attaining an altitude of 10,000 km above the earth's surface. At the present stage of the data reduction, confirmation is at the 2×10^–4 level of accuracy. The experiment and the resulting data are described including a comment on the limits to the anisotropy of the velocity of light. We believe that this is the first direct, high-accuracy test of the symmetry of the propagation of light and a beginning in the use of high-accuracy clocks in space to measure relativistic phenomena.This essay was awarded the fourth prize for 1978 by the Gravity Research Foundation. (Ed.)     

C-H-pi interactions in 1-n-butyl-3-methylimidazolium tetraphenylborate molten salt: solid and solution structures

The crystal structure of 1-n-butyl-3-methylimidazolium tetraphenylborate molten salt (1) shows C-H-pi interactions between the hydrogens of the imidazolium cation and the phenyl rings of the tetraphenylborate anion. The imidazolium ring is surrounded by three tetraphenylborate anions that are connected with the same cation by C-H-pi (phenyl rings) interactions. The nearest inter-ion interaction is found between the N-CH-N proton of the cation and the B-phenyl centroid (2.349 A) with a nearly T-shaped geometry. The inter-ionic solution structure of 1 has been investigated by the detection of inter-ionic contacts in 1H NOESY NMR spectra between the protons of the cation and the anion. The 1H-NMR spectra of molten salt 1 is almost independent of its concentration in [D6]DMSO solution, the imidazolium proton chemical shifts are in the expected region and there are no observable NOE effects between the protons of the cation with those of the anion, indicating that 1 behaves in [D6]DMSO as a solvent-separated ion pair. In CDCl3 the 1H-NMR spectra of 1 are concentration dependent and all the imidazolium protons are shielded as compared with those observed in [D6]DMSO. Moreover, the 1H NOESY NMR spectra show all the peaks affected by the interaction between the protons of the imidazolium cation and those of the anion, indicating that in CDCl3 1 possesses a contact ion pair structure. The NCHN proton of the cation exhibits the greatest shielding (up to -4.5 ppm). an indication of the existence of C-H-pi interactions, even in solution. The calculated distance of this proton to the phenyl centroid is 2.3 A for a C-H -pi angle of 180 degrees. The apparent volumes for the cation and anion, calculated from the measured 13C-NMR relaxation times, increase from 38 and 140 A3 in [D6]DMSO to 360 and 600 A3 in CDCl3, respectively; this indicates the formation of floating aggregates of the type (1)(n) in CDCl3 via weak hydrogen bonds, with increasing concentration.     

Effects of Adsorbed Polyaniline on Redox Processes on As(2)O(3) Surfaces

Polyaniline deposited on As(2)O(3) surface resulted in a new material, which was characterized by infrared spectoscopy, thermogravimetry, differential scanning calorimetry, scanning electron microscopy, X-ray diffraction, and cyclic voltammetry. The mass percentage of polymer deposited on oxide surface is approximately 13%. The scanning electron microscopy images as well as the X-ray diffraction patterns provided conclusive evidence that the oxide surface is coated by the polymer. The cyclic voltammograms of the polyaniline adsorbed on As(2)O(3) surface showed that the adsorbate exerts remarkable effects on redox processes on this oxide. The pure oxide exhibited two oxidation/reduction peaks at 0.25/-0.06 and 0.47/-0.25 V attributed tentatively to the processes As(2)O(3)(s)+6H(+)+6e(-)=2As(s)+3H(2)O and As(s)+3H(+)+3e(-)=AsH(3)(g), respectively. The polyaniline-coated sample exhibited a better-defined voltammogram in which the first oxidation peak of the oxide had its intensity increased about four times. Copyright 2000 Academic Press.