Tetracarbonyl cobaltate ion supported on anion exchangers as a new heterogenized homogeneous catalyst: synthesis of acids and esters from organic halides

Catalysts consisting of tetracarbonyl cobaltate anion supported on commercially available anion exchange resins are readily prepared. Carbonylation of organic halides using this heterogenized catalyst leads either to acids or esters depending on the conditions. Some features of this catalytic system and the possible reaction mechanism are discussed.     

Nickel-catalyzed synthesis of phosphonium salts

The nickel-catalyzed synthesis of phosphonium salts from aryl halides and triphenylphosphine is reported.The formation of phosphonium salts occurs by the oxidative addition reaction of Ni[P(C₆H₅)₃]₃ on the aryl halides and reaction of the coordinated aryl groups with triphenylphosphine.The influence of substituents on the aromatic nucleus is studied.     

Regioselective,Asymmetric Formal Hydroamination of Unactivated Internal Alkenes

We report the regioselective and enantioselective formal hydroamination of unsymmetrical internal alkenes catalyzed by a copper catalyst ligated by DTBM‐SEGPHOS. The regioselectivity of the reaction is controlled by the electronic effects of ether, ester, and sulfonamide groups in the homoallylic position. The observed selectivity underscores the influence of inductive effects of remote substituents on the selectivity of catalytic processes occurring at hydrocarbyl groups, and the method provides direct access to various 1,3‐aminoalcohol derivatives with high enantioselectivity.     

On Certain Identity Related to Herstein Theorem on Jordan Derivations

Let R be a 6-torsion-free prime ring and let \({D : R \rightarrow R}\) be an additive mapping satisfying the relation 2D(x ⁴) = D(x ³)x + x ³ D(x) + D(x)x ³ + xD(x ³) for all \({x \in R}\) . The purpose of this paper is to show that D is a derivation. This result is related to a classical result of Herstein, which states that any Jordan derivation on a 2-torsion-free prime ring is a derivation.     

Hair Growth Promoting Activity of Cedrol Nanoemulsion in C57BL/6 Mice and Its Bioavailability

As the main component of Platycladus orientalis, cedrol has known germinal activity. A range of cedrol formulations have been developed to prevent hair-loss, but compliance remains key issues. In this study, we prepared cedrol nanoemulsion (CE-NE) and determined the particle size and PDI (polydispersion coefficient), investigated the hair growth activity and studied the bioavailability in vitro and in vivo. Results showed that the average particle size of CE-NE is 14.26 ± 0.16 nm, and the PDI value is 0.086 ± 0.019. In vitro drug release investigation and drug release kinetics analysis showed release profile of CE from nanoparticles demonstrates the preferred partition of CE in buffer pH 4.0, the release profile of CE-NE showed a first-order kinetics reaching around 36.7% after 6 h at 37 °C. We artificially depilated the back hair of C57BL/6 mice and compared the efficacy of a designed cedrol nanoemulsion to an existing ointment group. The hair follicles were imaged and quantified using a digital photomicrograph. The results showed that compared with the ointment, CE-NE had positive effects on hair growth, improved drug solubility. Compared with the ointment and 2% minoxidil groups, 50 mg/mL CE-NE led to more robust hair growth. Pharmacokinetics analysis showed that the AUC_0–t of CE-NE was 4-fold higher than that of the ointment group, confirming that the bioavailability of the nanoemulsion was greater than that of the ointment. CE-NE also significantly reduced the hair growth time of model mice and significantly increased the growth rate of hair follicles. In conclusion, these data suggest that the nanoemulsion significantly improved the pharmacokinetic properties and hair growth effects cedrol, enhancing its efficacy in vitro and in vivo.     

Activity Components from Gynostemma pentaphyllum for Preventing Hepatic Fibrosis and of Its Molecular Targets by Network Pharmacology Approach

Hepatic fibrosis would develop into cirrhosis or cancer without treating. Hence, it is necessary to study the mechanism and prevention methods for hepatic fibrosis. Gynostemma pentaphyllum is a traditional medicinal material with a high medicinal and health value. In this study, nineteen compounds obtained from G. pentaphyllum were qualitative and quantitative by HPLC-FT-ICR MS and HPLC-UV, respectively. Among them, the total content of 19 gypenosides accurately quantified reaches 72.21 mg/g and their anti-proliferation against t-HSC/Cl-6 cells indicated compound 19 performed better activity (IC50: 28.1 ± 2.0 μM) than the other compounds. Further network pharmacology study demonstrated that compound 19 mainly plays an anti-fibrosis role by regulating the EGFR signaling pathway, and the PI3K–Akt signaling pathway. Overall, the verification result indicated that compound 19 appeared to be nontoxic to LO2, was able to modulate the PI3K/Akt signal, led to subG1 cells cycle arrest and the activation of mitochondrial-mediated apoptosis of t-HSC/Cl-6 cells for anti-hepatic fibrosis.     

润滑脂纤维结构对弹流油膜影响的试验研究

采用光干涉技术对脂润滑弹流油膜进行测量,分析了粗细两种稠化剂纤维结构对润滑脂膜厚的影响.试验结果表明:粗纤维结构的润滑脂稠化剂连续性好,可在滚道上形成较厚沉积层,在新鲜供脂条件下其油膜厚度是细纤维润滑脂的2到5倍.在首次升速-降速过程中润滑膜厚呈现明显差异;而在升速-降速多次循环后,膜厚曲线趋向一致.     

苯胺低聚体的合成与表征

苯胺低聚体从结构上可分为三种类型,即苯／胺,双胺和双苯封端的苯胺低聚体。本文从这三种结构出发综述了近几年来苯胺低聚体的合成与光谱表征。     

光果甘草乙酸乙酯相对酪氨酸酶的抑制作用

酪氨酸酶是生物体合成黑色素的关键酶,实验以光果甘草为原料,研究其提取物乙酸乙酯相对酪氨酸酶活性的抑制作用及机理.采用L-多巴速率氧化法体外测定光果甘草提取物乙酸乙酯相对酪氨酸酶的抑制活性,并绘制了Lineweaver-Burk双倒数曲线以此判断其抑制类型.结果表明光果甘草提取物乙酸乙酯相半抑制浓度(IC50)为(266.5±1.4)mg/L.对酪氨酸酶抑制机理测定分析的结果表明,光果甘草提取物乙酸乙酯相对酪氨酸酶活性的抑制作用表现为可逆抑制,对酪氨酸酶活性的抑制类型是混合型抑制,抑制常数KI为(182.86±1.43)mg/L,α值为(15.49±0.68)mg/L.可见甘草提取物乙酸乙酯相对酪氨酸酶有较强抑制作用.     

Brazilian bioethanol program

Brazil is the largest producer of bioethanol, and sugarcane is the main raw material. Bioethanol, is produced by both batch and continuous processes, and in some cases, flocculating yeast is use. This article analyzes the Bracilian Ethanol Program. for the 1996–1997 havest, Brazil produced 14.16 billion L of ethanol and 13.8 million metrict of sugar, from 286 million metrict of sugarcane. These products were produced by 328 industries inactivity, with 101 autonomousethanol plants producing only ethanol, and 227 sugar mills producing sugar and ethanol. The sugar-ethanol market reaches about 7.5 billion US$/yr, accounting for direct and indirect revenues.