龙爪芦荟和库拉索芦荟中微量锗的测定与红外光谱区别

采用吸光光度法对龙爪芦荟和库拉索芦荟中的微量锗进行了测定,并探讨了两种芦荟的红外光谱的区别。结果表明,龙爪芦荟中含锗量在26.1～28.6μg·g-1,回收率为91.6%～97 5%。库拉索芦荟中含锗量在16.8～20.0μg·g-1,回收率为87.1%～94.5%。两种芦荟的FT IR光谱图在2100cm-1处有明显差异,由此可区别两种芦荟。     

Kinetic model of catalytic ethylene oxidation

The kinetics of ethylene oxidation on a pumice supported silver catalyst promoted with chlorine has been studied. A simplified kinetic equation with two parameters is given to describe the process over a wide range of ethylene concentrations. The parameters of the equation have been determined as a function of the temperature.

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Krametosan, a new trinorlignan from the roots of Krameria tomentosa

A new phenylcoumarone type trinorlignan, krametosan (1), along with the known norlignans, ratanhiaphenol I (2) and 2-(2'-hydroxy-4',6'-dimethoxyphenyl)-5-(E)-propenylbenzofuran (3), the lignan conocarpan (4) and dinorlignan decurrenal (5), were isolated from the CHCl3 extract of the roots of Krameria tomentosa. The structure of these compounds were elucidated by the spectroscopic methods.     

LIGHT PROMOTION OF SEED GERMINATION IN Datura ferox IS MEDIATED BY A HIGHLY STABLE POOL OF PHYTOCHROME

Abstract— The duration of the far-red light-absorbing form of phytochrome (Pfr) of the photoreceptor pool involved in the control of seed germination was investigated for Datura ferox seeds. These seeds require both Pfr and alternating temperatures (20/30°C) to germinate. After 24 h imbibition (25°C), the seeds received pretreatment-light pulses providing different phytochrome photoequilibria (Pfr/P), followed by a 24 h dark incubation (25°C), and test-light pulses providing different Pfr/P immediately prior to transfer to alternating temperatures. Germination increased with increasing Pfr/P provided by the test-light pulses, but was unaffected by the pretreatment-light pulses. This suggests that phytochrome synthesis, phytochrome degradation and phytochrome-mediated changes in response to phytochrome were negligible. In other experiments, red light-pretreatment pulses were followed by dark incubations (25°C) of different duration before transfer to alternating temperatures. The proportion of Pfr remaining after the 25°C incubation period was estimated by comparing germination rates with those of seeds that received test-light pulses of known calculated Pfr/P immediately prior to the start of the cycles of alternating temperatures. More than 80% of the Pfr established by a Pfr/P= 0.87 light pulse was present and active even after 48 h dark incubation at 25°C. Surprisingly, when a pretreatmentlight pulse providing a Pfr/P= 0.70 was given, the reduction in [Pfr] was significantly faster.
Germination of Datura ferox seeds is under the control of a highly stable (type II like) phytochrome pool. Apparently, this pool follows Pfr dark reversion to the red light-absorbing form, the times to reach half the original Pfr pool being > 96 h or <14 h after light pulses providing Pfr/P= 0.87 or 0.70, respectively.     

Ethylene and Cyclohexene Oxidation by p-Benzoquinone,Hydrogen Peroxide,and Oxygen in the Solutions of Cationic Pd(II) Complexes in Acetonitrile–Water and Ionic Liquid–Water Binary Solvents

Kinetics and Catalysis - Optimal conditions are selected for ethylene and cyclohexene oxidation reactions in the acetonitrile (AN)–water system in the presence of...     

Bruhat Numbers of a Strong Morse Function

Doklady Mathematics - Let f be a Morse function on a manifold M such that all its critical values are pairwise distinct. Given such a function (together with a certain choice of orientations) and a...     

Kinetic isotope effects in oxidation reaction of C2H4 and C2D4 by p-benzoquinone in the Pd2+—HClO4—CH3CN—H2O system

Russian Chemical Bulletin - Kinetic isotope effects (KIE) have been measured for oxidation reactions of ethylene by p-benzoquinone in Pd2+—MeCN—H2O—HClO4 system. Under the...