Development of a general approach to the synthesis of a library of isoflavonoid derivatives

Isoflavonoids are a class of organic compounds that act primarily as antioxidants. They are produced almost exclusively by various members of the bean family including soybeans, tofu, peanuts, chick peas, and alfalfa. The antioxidant characteristics that isoflavonoids exhibit help hinder the progression of certain cancers, primarily breast, prostate, and colon cancer. We have developed a three-five step synthesis for obtaining a suite of isoflavonoid derivatives. The synthesis involves an enamine formation, a ring closure and halogenation, a Suzuki coupling, and finally a global deprotection to obtain the respective isoflavonoid derivatives.     

Efficient synthesis of functionalized 6-substituted-thiosalicylates via microwave-promoted Suzuki cross-coupling reaction

Functionalized 6-substituted-thiosalicylates are key intermediates for the synthesis of pyrimidinyl(thio)salicylic acids, a group of important herbicides targeting plant acetohydroxyacid synthase. Therefore, it is of great interest to develop an efficient method for the syntheses of 6-substituted-thiosalicylates. Herein, we have developed a direct and efficient method for the synthesis of functionalized 6-substituted-thiosalicylates (4) from aryl iodide (1) by using an improved microwave-assisted Suzuki cross-coupling reaction. Almost all the reactions proceeded smoothly and afforded moderate to excellent yields of products. Moreover, this protocol is obviously superior to the traditional available methods and could be utilized to synthesize pyrimidinyl(thio)salicylic acid and its derivatives.     

An appraisal of the Suzuki cross-coupling reaction for the synthesis of novel fluorescent coumarin derivatives

We report the chemical design and development of 3-aryl-substituted 7-alkoxy-4-methylcoumarins with enhanced fluorogenic properties. The 3-aryl substituents are installed via an optimized Suzuki–Miyaura cross-coupling (SMC) reaction between a 7-alkoxy-3-bromo-4-methylcoumarin and aryl boronic MIDA esters using Pd(OAc)₂/XPhos in a catalytic system with K₂CO₃ in aqueous THF. Under these conditions, an exocyclic ester functionality is found to be unaffected. Subsequent saponification revealed a carboxylic acid functionality that is suitable for conjugation reactions. Evaluation of their fluorescence properties indicated that the installed 3-heteroaryl substituent, particularly benzofuran-2-yl, resulted in a significant red shift of both the excitation and emission wavelengths.     

DOUBLESLICING: a non-iterative single profile multi-exponential curve resolution procedure. Application to time-domain NMR transverse relaxation data

A new non-iterative curve resolution technique for resolving single decay profiles is proposed. The new technique, called DoubleSlicing, is based on the Decra (Direct Exponential Curve Resolution Algorithm) principle. While the original Decra was designed to resolve several decay curves simultaneously and thus fitting common pure exponentials, DoubleSlicing can resolve single decay profiles by a simple double data transformation followed by an analytical and unique three-way decomposition. The new approach is successfully demonstrated on experimental NMR CPMG relaxation data, measured on combinations of unmixed paramagnetic CuSO(4) solutions. Decay signals of the water component were acquired following an innovative experimental design that ensured no interaction between the components present in each sample under observation. DoubleSlicing proved to be accurate in estimating relaxation times differing in one order of magnitude (range: 19.6-159.4ms). Its performance was comparable to discrete exponential fitting with the advantage of being much faster - in terms of computation time, DoubleSlicing outperformed exponential fitting by a factor of four.     

光生物节律因子计算模型的研究

通过实验测量额头温度拟合光生物节律因子-额温差曲线,对现有评价光生物效应作用大小的BioEq模型和CLA模型的计算结果进行分析比较.利用不同图片LCD屏幕的光谱计算节律因子,发现两种模型对于绿色波段的光抑制较强,而对红色波段的光则与实际不相符.通过对九种不同颜色的LED光源测试额头温度,比较模型计算结果与实际光生物效应的作用,发现光生物节律因子与生理体征变化线性递增,其中对BioEq模型的直线拟合相关度达到0.95.     

Sulfur removal from bauxite water slurry (BWS) electrolysis intensified by ultrasonic

Effects of ultrasonic on desulfurization ratio from bauxite water slurry (BWS) electrolysis in NaOH solution were examined under constant current. The results indicated that ultrasonic improved the desulfurization ratio at high temperatures because of the diffusion and transfer of oxygen gas in electrolyte. However, due to the increase in oxygen gas emission, ultrasonic could not improve the desulfurization ratio obviously at low temperatures. Additionally, the particle size of bauxite became fine in the presence of ultrasonic, indicating that the mass transfer of FeS₂ phase was improved. According to the polarization curves, the current density increased in the presence of ultrasonic, indicating that the mass transfer of liquid phase was improved. The apparent activation energy (AAE) of electrode reaction revealed that ultrasonic did not change the pathway of water electrolysis. However, ultrasonic changed the pathway of BWS electrolysis, converting indirect oxidation into direct oxidation. The AAE of BWS electrolysis in the presence of ultrasonic was higher than that in the absence of ultrasonic. And the low AAEs (less than 20 kJ/mol) clearly indicated the diffusion control during BWS electrolysis reaction.     

Facile synthesis of palladium nanoparticles supported on urea-based porous organic polymers and its catalytic properties in Suzuki-Miyaura coupling

By using urea linked porous organic polymers as template, a new nano palladium catalyst with low Pd loading can be easily prepared (1.0 wt% Pd only). Although such less amount of Pd was contained in this new catalyst, it is still an effective catalyst for the Suzuki-Miyaura coupling of aryl iodines and aryl boric acids, affording biphenyl products in excellent yields with outstandingly enhanced turnover numbers (up to 10,536) under green solvent (water).     

椭圆曲线y2=(x+p)(x2+p2)的本原整数点

设p是奇素数.本文给出了椭圆曲线y2=(x+p)(x2+p2)存在可使y为偶数的本原整数点(x,y)的充要条件.     

优化端点条件的平面二次均匀B样条插值曲线

在利用反求法构造B样条插值曲线时,往往需要选取端点条件。 因此,可对端点条件进行优化选取,使得构造的B样条插值曲线满足特定要求。提出了一种利用曲线内能极小选取平面二次均匀B样条插值曲线端点条件的算法。首先给出了二次均匀B样条插值曲线分控制顶点与首个控制顶点（即端点条件）的递推关系式;然后给出了利用曲线内能极小优化选取首个控制顶点的算法,证明了利用该算法构造的C¹连续二次均匀B样条插值曲线为保形插值,并通过数值算例证明了算法的有效性;最后,为便于实际应用,基于MATLAB平台设计了算法所对应的图形用户界面,用户通过简单的操作即可获得光顺的C¹连续二次均匀B样条保形插值曲线。     

Screening of Yeast in Various Vineyard Soil and Study on Its Flavor Compounds from Brewing Grape Wine

In order to screen out Saccharomyces cerevisiae suitable for table grape fermentation, and compare it with commercial Saccharomyces cerevisiae in terms of fermentation performance and aroma producing substances, differences of fermentation flavor caused by different strains were discussed. In this experiment, yeast was isolated and purified from vineyard soil, 26s rDNA identification and fermentation substrate tolerance analysis were carried out, and the causes of flavor differences of wine were analyzed from three aspects: GC-MS, PCA and sensory evaluation. The results showed that strain S1 had the highest floral aroma fraction, corresponding to its high production of ethyl octanoate and other substances, and it had the characteristics of high sugar tolerance. The fruit sensory score of S3 wine was the highest among the six wines. Through exploration and analysis, it was found that compared with commercial Saccharomyces cerevisiae, the screened strains had more advantages in fermenting table grapes. The flavor of each wine was directly related to the growth characteristics and tolerance of its strains.