光活化农药的研究与应用

结合作者近期的研究工作，对光活化农药的研究现状、作用机理、应用前景及其与新农药创 制的关系进行了综述。     

Echocardiographic evaluation of the effects of medetomidine and xylazine in dogs

The echocardiographic effects of medetomidine and xylazine were evaluated in 6 healthy dogs. Values for echocardiographic variables were significantly different from pre-treatment values after administration of both drugs. The effects of medetomidine were similar to that of xylazine. Because of their cardiac depressant effects, both drugs should be used with care in sick dogs.     

京郊葫芦科作物花叶病毒的类型初报

从1957到1958年,在北京都区进行了瓜类作物花叶病毒的调查研究。在记述病作物症状的同时,还采集了各类花叶病株的标样,进行了病毒的常规鉴定。西葫芦的花叶病是一个严重的病毒病,鉴定的结果证明其毒原主要为典型的甜瓜花叶病毒(MMV),而且能侵染西瓜而产生系统性花叶症。在南瓜的花叶病标样中分离到的也是甜瓜花叶病毒,但是这个株系不同于典型的甜瓜花叶病毒,因为它们都不侵染西瓜。从黄瓜花叶病标样中分离出来的病毒全属于黄瓜花叶病毒种羣(GMV),其中可能有不同的株系,而秋黄瓜上却分离出了一个毒原,不侵染心叶菸,系统侵染普通菸和毛叶菸,在蔓陀蘿叶上产生局部枯斑而具有较高的致死温度(85℃)。作者认为这可能是一个新单元,称之为秋黄瓜花叶病毒(ACMV)。所有在甜瓜,哈密瓜及绞瓜上分离出来的毒原都是属于典型甜瓜花叶病毒的,但梢瓜(即白瓜)上的毒原都是黄瓜花叶病毒(CMV),没有广州报告的白瓜花叶花病毒。丝瓜花叶病的分离物类似甜瓜花叶病毒,但寄主范围远较狭隘,很可能是一个甜瓜花叶病毒的新株系。     

应用敌百虫防治荔枝蝽象的大田试验

荔枝蝽象是华南地区的重要害虫之一。作者根据此虫自然抗药性季节变化的規律,結合荔枝的开花結果时期,采用有机磷杀虫剂敌百虫0.067％水溶液噴雾于3月中及5月初各噴药一次,防治效果达95％以上。基本可以消灭荔枝蝽象成虫及若虫的为害,达到保花保果的要求。根据試驗結果,掌握上述两个时期大面积噴敌百虫,对荔枝开花、結果以及品质,均无不良影响。噴药时最好暫时关閉蜂箱,噴药后再放蜂。大面积使用敌百虫防治荔枝蝽象,成本低廉,每株药剂及人工費用为0.177元,每亩15株計算,每亩費用为2.65元。防治时期,最好选择能在3—4天內天晴、气温较高、风力0—1級为宜,噴雾要求均匀周到。     

Effects of thinning and pruning on knots and lumber recovery of Taiwania (<Emphasis Type="Italic">Taiwania cryptomerioides</Emphasis>) planted in the Lu-Kuei area

This study investigated the effects of various thinning and pruning methods on the knots (number and size) and lumber recovery from Taiwania (Taiwania cryptomerioides Hay.) plantation trees. The results showed that heavy thinning caused more knots and larger-diameter knots than medium or no thinning; moreover, pruning caused fewer numbers of knots and smaller-diameter knots than no pruning. Better-quality Taiwania trees occurred with the no-thinning/no-pruning treatments, as shown by analyzing the knots, although the results also showed that the healing process seemed to have produced not completely clear wood during the 9 years after the pruning treatment. The thinning intensity slightly enhanced the lumber recovery of logs. Pruning did not affect lumber recovery from taiwania trees and logs. Thinning increased the lumber recovery per tree due to an increase in the diameter at breast height.     

Designed polar cosolvent-modified supercritical CO2 removing caffeine from and retaining catechins in green tea powder using response surface methodology

This study examines cosolvent-modified supercritical carbon dioxide (SC-CO2) to remove caffeine from and to retain catechins in green tea powder. The response surface method was adopted to determine the optimal operation conditions in terms of the extraction efficiencies and concentration factors of caffeine and catechins during the extractions. When SC-CO2 was used at 333 K and 300 bar, 91.5% of the caffeine was removed and 80.8% of catechins were retained in the tea: 3600 g of carbon dioxide was used in the extraction of 4 g of tea soaked with 1 g of water. Under the same extraction conditions, 10 g of water was added to <800 g of carbon dioxide in an extraction that completely removed caffeine (that is, the caffeine extraction efficiency was 100%). The optimal result as predicted by three-factor response surface methodology and supported by experimental data was that in 1.5 h of extraction, 640 g of carbon dioxide at 323 K and 275 bar with the addition of 6 g of water extracted 71.9% of the caffeine while leaving 67.8% of the catechins in 8 g of tea. Experimental data indicated that supercritical carbon dioxide decaffeination increased the concentrations of caffeine in the SC-CO2 extracts at 353 K.     

Effect of pH on binding of mutagenic heterocyclic amines by the natural biopolymer poly(gamma-glutamic acid)

Poly(gamma-glutamic acid) (gamma-PGA), a nontoxic and biodegradable macropolymer, was evaluated for its efficiency in binding three mutagenic heterocyclic amines (HAs), 2-amino-3,4-dimethylimidazo[4,5-f]quinoline (MeIQ), 2-amino-3,4,8-trimethylimidazo[4,5-f]quinoxaline (4,8-DiMeIQx), and 3-amino-1-methyl-5H-pyrido[4,3-b]indole (Trp-p-2), as affected by pH in a batch mode. The maximum HA sorption was attained for pH 3-7 and decreased sharply for pH less than 3. Binding isotherms obtained at pH 2.5 and 5.5 showed different isotherm shapes that belong to S and L types, respectively. The isotherm data at pH 2.5 were well described by a linear form of the Langmuir equation, while at pH 5.5 it showed two distinct curves, which were precisely fitted as multiple Langmuir curves. The deviation of linearity in Scatchard plot proved the multisite HA sorption. The Brunauer-Emmett-Teller equation also fitted better to isotherm data at pH 5.5, suggesting a multisite sorption caused by multimolecular HA layers on gamma-PGA. High HA sorption levels of 1250, 667, and 1429 mg/g at pH 2.5 and 1429, 909, and 1667 mg/g at pH 5.5 were observed for MeIQ, 4,8-DiMeIQx, and Trp-p-2, respectively. Among the HAs studied, the sorption capacity correlated directly with hydrophobicity of HAs and inversely with the number of methyl groups in HA molecules. The plausible binding mechanism of HAs on gamma-PGA may include a combination of hydrophobic, hydrogen-bonding, ionic, and dipole-dipole interactions.