Evidence for a new phase transition in Rb2ZnCl4 by Raman scattering

The Raman spectra of an oriented single crystal of Rb₂ZnCl₄ give evidence for the existence of a phse mode at low temperature, as predicted by Wada et al. A new soft mode whose frequency decreases as the temperature T₃?72 K is approached from below, was observed in the a(cc)b scattering orientation, strongly supporting the onset of a new phase transition.     

L.D.A. Simultaneous Measurements of Local Density and Velocity Distribution of Particles in Plasma Fluidized Bed at Atmospheric Pressure

Laser Doppler anemometry (L.D.A.) is an efficient and nonintrusive technique. Today, improved in its configuration, the L.D.A. has been applied even in flowing plasmas. ^(1,2) In-flight simultaneous measurements were performed for local density and velocity of particle distribution. The measurements provide an insight into thermal and mass transfer, chemical reactivity, and the distribution of residence times of particles in a plasma fluidized bed. The difficulties of L.D.A. in a plasma fludized bed such as high emission intensity of the plasma torch, high temperature, high particle density, and large distribution of particle granulometry were overcomed in the present investigation. The aims achieved were the characterization of the plasma fluidized bed distribution together with accurate measurements of local particle density and velocity as measured by L.D.A.     

Chemical ionization (NO) spectra of n-alkenoic acids and their esters

It is shown that the position of one double bond in long-chain unsaturated fatty acids and their esters can be determined by chemical ionization (NO) mass spectra. Homoconjugated dienoic acids (as linoleic acid) do not give a characteristic framentation pattern, in contrast to those which contain three or more homoconjugated double bonds.     

A grazing-incidence dye laser with an intracavity lens

The performance of a nitrogen-laser-pumped dye laser, using a grating at grazing-incidence is greatly improved by inserting a lens between the dye cell and the grating. Long term operation of the laser with a 1.1 GHz linewidth is demonstrated.     

2,9-dioxabicyclo[4.2.1]Nonan - darstellung,massenspektroskopie und umlagerung eines neuen heterocyclischen systems

Nine different methyl-substituted compounds of a new acetal system $\text{5}$ are synthesized from 4-(5-methyl-2-furyl)alkanoles $\text{1}$ and are rearranged to ketones $\text{6}$; mass spectroscopic fragmentation patterns are described.     

微波消解ICP-MS测定唐古特乌头中的多种微量元素

采用HNO3-H2O2混合酸体系微波消解及电感耦合等离子体-质谱法,消解唐古特乌头样品,测定其中Mn、Fe、Co、As、Ni、Se、Cu、Zn、V和Cr共10种微量元素。探讨了样品消解的条件,通过加标回收实验,回收率为94.08%—103.50%,验证了分析数据的可靠性。结果表明,该法具有快速、简便、准确度高、能同时分析多元素的优点,结果令人满意。     

肉苁蓉精油化学成分的研究

肉苁蓉 Cistanche Salsa(C.A.Mey.)G.Beak 是列当科 Orobanchaceae 植物肉苁蓉的肉质茎;又名大芸,纵蓉。它分布在北疆地区荒漠戈壁地带,有益肾壮阳,延年益寿等功能,故有“沙漠人参”之称。肉苁蓉是一种常用的中药,新疆地区资源丰富,其精油化学成分在国内外未见报道。为了整理和发掘祖国医药学宝库,我们对其化学成分进行了研究。     

Electrochemistry and Reactivity of Chelation-stabilized Hypervalent Bromine(III) Compounds

Hypervalent bromine(III) reagents possess a higher electrophilicity and a stronger oxidizing power compared to their iodine(III) counterparts. Despite the superior reactivity, bromine(III) reagents have a reputation of hard-to-control and difficult-to-synthesize compounds. This is partly due to their low stability, and partly because their synthesis typically relies on the use of the toxic and highly reactive BrF₃ as a precursor. Recently, we proposed chelation-stabilized hypervalent bromine(III) compounds as a possible solution to both problems. First, they can be conveniently prepared by electro-oxidation of the corresponding bromoarenes. Second, the chelation endows bromine(III) species with increased stability while retaining sufficient reactivity, comparable to that of iodine(III) counterparts. Finally, their intrinsic reactivity can be unlocked in the presence of acids. Herein, an in-depth mechanistic study of both the electrochemical generation and the reactivity of the bromine(III) compounds is disclosed, with implications for known applications and future developments in the field.