AMPK regulates NADPH homeostasis to promote tumour cell survival during energy stress

Overcoming metabolic stress is a critical step for solid tumour growth. However, the underlying mechanisms of cell death and survival under metabolic stress are not well understood. A key signalling pathway involved in metabolic adaptation is the liver kinase B1 (LKB1)-AMP-activated protein kinase (AMPK) pathway. Energy stress conditions that decrease intracellular ATP levels below a certain level promote AMPK activation by LKB1. Previous studies showed that LKB1-deficient or AMPK-deficient cells are resistant to oncogenic transformation and tumorigenesis, possibly because of the function of AMPK in metabolic adaptation. However, the mechanisms by which AMPK promotes metabolic adaptation in tumour cells are not fully understood. Here we show that AMPK activation, during energy stress, prolongs cell survival by redox regulation. Under these conditions, NADPH generation by the pentose phosphate pathway is impaired, but AMPK induces alternative routes to maintain NADPH and inhibit cell death. The inhibition of the acetyl-CoA carboxylases ACC1 and ACC2 by AMPK maintains NADPH levels by decreasing NADPH consumption in fatty-acid synthesis and increasing NADPH generation by means of fatty-acid oxidation. Knockdown of either ACC1 or ACC2 compensates for AMPK activation and facilitates anchorage-independent growth and solid tumour formation in vivo, whereas the activation of ACC1 or ACC2 attenuates these processes. Thus AMPK, in addition to its function in ATP homeostasis, has a key function in NADPH maintenance, which is critical for cancer cell survival under energy stress conditions, such as glucose limitations, anchorage-independent growth and solid tumour formation in vivo.     

煤系黄铁矿的电解催化氧化和动力学研究

以硫酸为介质，硫酸锰为电解催化剂，在以铂为电极的无隔膜电解池中研究了煤系黄铁矿的电化学催化氧化。研究表明，煤系黄铁矿中硫的转化率随着电解电位的提高，锰离子浓度的增加、煤浆浓度的降低、煤颗粒直径的变小、电解质酸度的增加和电解温度的提高而提高。进而对这些数据进行了动力学分析。结果表明煤系黄铁矿的电化学氧化反应符合未反应缩核模型，Mn^3 与黄铁矿表面发生的氧化反应是控制步骤，该反应的表面活化能的29.6kj/mol。     

NADPH结构类似物对FMN电子传递性质影响的研究

研究了NADPH结构类似物稳定黄素单核苷酸（FMN）功能域屏蔽状态的作用机理.以野生型一氧化氮合成酶还原酶（nNOSr）、突变体nNOSrF1395S、突变体nNOSrR1400E为对象,研究了NADPH结构类似物：2＇-AMP、2＇,5＇-ADP、硫代-NADP＋、3-乙酰吡啶-NADP＋对FMN域的屏蔽和去屏蔽两种状态的影响,证实了烟碱基团对电子传递过程的影响.     

三价铁化合物对安息香的氧化

以六水合三氯化铁,十二水合硫酸铁铵、九水合硝酸铁和六水合硫酸铁为氧化剂,从安息香合成了苯偶酰,其收率达８１％－９５％。     

Oxidation behavior of Hf-modified platinum aluminide coatings during thermal cycling

Platinum aluminide coatings with different Hf contents were fabricated by using HfCl_4. The oxidation kinetics and the rumpling behavior of oxide scale were investigated. After thermal cycling, the coating with 0.46 wt% Hf showed least weight gain. With the increase of Hf content, rumpling extent of the scale decreased. Meanwhile, HfO_2 preferentially formed in the scale resulting in the increase of scale thickness. The oxidation of excessive Hf even caused the spallation of the scale. The results in the present study indicate that although Hf plays an important role in decreasing rumpling extent of TGO, the oxidation of Hf decreases the adhesion of the scale.     

铬铁矿球团焙烧固结特性

本文系统研究铬铁矿球团的焙烧固结特性.结果表明：预热时间对于预热球强度影响不大,在预热时间为10 min时,随着预热温度的提高,预热球强度和氧化率呈直线型增加,适宜温度为1050益,此时预热球强度可达每个400 N以上;与传统铁矿球团相比,铬铁矿球团焙烧所需的温度高,焙烧时间为10 min时,焙烧温度从1250益提高到1350益,球团强度从每个1078 N提高到1973 N.在铬铁矿球团预热和焙烧过程中,铬尖晶石( Fe,Mg)( Cr,Fe,Al)2 O4氧化生成富镁的( Fe,Mg)( Cr, Fe,Al)2O4和铬铁铝复合氧化物(Cr,Fe,Al)2O3,当温度高于1000益时,(Cr,Fe,Al)2O3新相生成,其主要以环状分布在颗粒外层,颗粒内部为针状与(Fe,Mg)(Cr,Fe,Al)2O4形成交织结构,降低Cr/Fe比或升高焙烧温度均有助于(Cr,Fe,Al)2O3向颗粒外层富集和再结晶长大,有利于球团的固结,提高球团强度.     

二乙酸碘苯氧化卟啉原

报道了生成meso-四苯基卟啉时，用二乙酸碘苯作为氧化剂，将卟啉原氧化，目标化合物收率为46％．     

盐酸二甲胺三氧化铬对肟的氧化

本文报道了盐酸二甲胺三氧化铬对肟的氧化反应，该反应条件温和，产物分离简单，产率也很高，在有机合成中可用于以生成肟保护羰基并使羰基的再生