Studies of photoconductivity in β-Apo-8′ carotenal

The photoconductive properties of a carotenoid polyene,β-Apo-8′ carotenal in polycrystalline form has been studied. The growth of the photocurrent shows an overshoot in the growth-time curve before steady state value is attained. This behaviour of photocurrent is proposed to be due to higher value of recombination coefficient than trapping coefficient. From the temperature dependence study it is observed that the steady state photocurrent, at first increases with increase of temperature, attains a maximum at a particular temperatureT _max and then decreases with temperature. TheT _max value agrees with the temperature above and below which steady state photocurrent is attained differently. Monomolecular and bimolecular recombination processes at two temperature regimes are proposed to account for the observed behaviour. The dependence of photocurrent with excitation light intensity and wavelength study provide information on the carrier generation processes. The fast decay of photocurrent have been observed at different temperatures and from this study the decay constant is calculated and it is found to be temperature independent.     

取代二苯多烯和取代聚二乙炔的三阶非线性光学性质

为了设计新的具有较高非线性极化率和光损耗小的有机非线性光学（ＮＬＯ）材料，需要了解不同的有机结构对分子非线性的影响。在此基础之上，建议用平行对比的方法来近似估算取代二苯多烯和聚二乙炔（ＰＤＡ）的三阶非线性光学极化率。     

不饱和环缩醛／多硫醇体系的光交联

本文研究了3,9-二丙烯基-2,4,8,10-四氧螺[5,5]十三烷(DPTST)和四巯基醋酸季戊四醇酯(PTMA)以苯乙酮衍生物、安息香醚和芳酮作光引发剂时的光交联。通过测定双键在1680cm~(-1)和巯基在2570cm~(-1)处的红外吸收随光照时间的变化以及凝胶转化率和硬度随光照时间的变化来表征光交联动力学。 光交联速度与组分配比、光引发剂性质及含量有明显关系。以苯乙酮衍生物和α,α-二甲氧基-α-苯基苯乙酮为光引发剂、DPTST/PTMA的摩尔比为2:1到3:1时,得到较好的实验结果。     

邻氯苯基荧光酮光度法测定聚烯烃树脂中的钛

研究了以邻氯苯基荧光酮-十六烷基三甲基溴化铵为显色体系,在表面活性剂十六烷基三甲基溴化铵存在下,钛（Ⅳ）和邻氯苯基荧光酮所形成橙红色的络合物,实验结果表明,在酸性介质中钛（Ⅳ）最大吸收波长位于560nm,含量在0～12μg/25mL范围内符合比尔定律,其表观摩尔吸光系数ε560=1.2×10~5L·mol^-1·cm~（-1）。聚烯烃树脂的人工合成样中钛（Ⅳ）的平均回收率为101.9%,相对标准偏差为0.36%。采用抗坏血酸掩蔽剂消除了被测样中干扰离子的影响,实验结果表明聚乙烯和聚丙烯中钛（Ⅳ）的含量分别为0.1760μg·g^-1、0.6855μg·g^-1,其加标平均回收率分别为101.7%、99.8%。相对标准偏差分别为1.48%、2.43%。本方法选择性好,灵敏度高,简便易行。     

Methods for the Recovery and Purification of Polyene Antifungals

Despite the development of newer antifungal drugs, the polyene antifungals continue to be the most potent broad-spectrum fungicides available for clinical use. The incidence and severity of fungal infections are on the rise, underscoring the need for new and more effective antifungal drugs. Thus, the search for new polyene antifungals is ongoing. The limited solubility, polymorphic character, and inherent chemical instability of these compounds make their economical recovery and purification from mass culture challenging problems in biotechnology. This article provides a comprehensive review of the methods that have been developed for the recovery and purification of amphotericin B and nystatin, the two most important polyenes currently in clinical use.     

Optimization of cultivation conditions for fungichromin production from Streptomyces padanus PMS-702

A novel strain, Streptomyces padanus PMS-702, was employed to produce fungichromin (FC, a polyene macrolide antibiotic) in a shake flask cultivation. In comparing the effects of various carbon and nitrogen sources on PMS-702 cultivation, it was found that glucose and soybean meal medium yielded the highest FC within 2 days. Factors such as medium composition, cultivation temperatures, and initial pH were optimized for FC production with response surface methodology (RSM). The optimal cultural condition obtained is as follows: glucose 11.2 g/L, soybean meal 11.2 g/L, CaCO₃ 0.46 g/L, temperature 31.7 °C, and an initial pH 5.5. Under these conditions, FC production reached 112 mg/L, about an increase of 2.86 times, as compared to results under basic conditions.     

Application of the Cplex-isoelectronic theory to electrocyclisations,sigmatropic rearrangements,cheletropic reactions and antiaromaticity: Consistent with Santilli's hadronic chemistry

The recently proposed Cplex-isoelectronic theory is applied to electrocyclisation/ring opening reactions, sigmatropic rearrangements, cheletropic reactions and antiaromaticity. The Cplex-isoelectronic theory is consistent with the experimental data and makes different predictions from the present quantum chemical methods in some cases, namely a stepwise pathway for the conrotatory photochemical ring opening of 1,3-cyclohexadiene, a concerted photochemical electrocyclisation for 1,3-cyclohexadiene via disrotatory motion, a concerted suprafacial [1,5] sigmatropic shift with inversion for norcaradiene, a concerted suprafacial [1,3] carbon shift with inversion and retention, a concerted suprafacial photochemical [1,5] hydrogen migration, a concerted photochemical [3,3] shift, stabilisation of cyclic 4nπ$4n\pi$ electron systems by delocalisation and their excess energy is due only to electronic repulsion and strain, the monohomocyclopropenium and cyclopropenyl cations are not ‘aromatic’. The available empirical evidence is consistent with these new predictions. This finding is consistent with Santilli's hadronic chemistry which proposes that the present quantum chemical theories require the addition of a small correction factor for molecules with two or more electrons. It is also consistent with the fact that it is impractical to calculate an exact representation for complex chemical systems using quantum based methods. Replacing double bonds with strained systems, such as the norbornene ring, is predicted to convert stepwise pathways to concerted.     

Methods for the Recovery and Purification of Polyene Antifungals

Despite the development of newer antifungal drugs, the polyene antifungals continue to be the most potent broad-spectrum fungicides available for clinical use. The incidence and severity of fungal infections are on the rise, underscoring the need for new and more effective antifungal drugs. Thus, the search for new polyene antifungals is ongoing. The limited solubility, polymorphic character, and inherent chemical instability of these compounds make their economical recovery and purification from mass culture challenging problems in biotechnology. This article provides a comprehensive review of the methods that have been developed for the recovery and purification of amphotericin B and nystatin, the two most important polyenes currently in clinical use.     

FIBRED MAGNESIUM HYDROXIDE AND FLAME-RESISTANT POLYENE MATERIAL

The fibred mangesiun hydroxide from the bracite was treated with a surface active agent. The modified fibred magesium hydroxide as flame-retardant, boric acid, barium stearate, polydimethyl siloxane fluid, vinyltriethoxysilane as synergists of the flame-retardant were added to polyene resin. The flame-resistance polyene material prepared meets the requirements of EWCZ-6287-1.