SIRT4通过抑制GLS2表达增强肝细胞癌对索拉菲尼敏感性的研究

目的:探索Sirtuin4(SIRT4)调控肿瘤谷氨酰胺代谢的机制,明确SIRT4对肝癌细胞干性及索拉菲尼治疗敏感性的影响。方法:通过实时定量PCR(real-time quantitative reverse transcription PCR,qRT-PCR)和免疫组织化学染色检测SIRT4在肝癌中的m RNA和蛋白表达水平。免疫印迹及细胞成球实验检测肿瘤细胞干性,细胞计数实验(CCK-8)和平板克隆实验检测肝癌细胞索拉菲尼治疗敏感性。免疫共沉淀检测SIRT4对蛋白的去乙酰化作用。结果:在肝癌的临床样本组织和细胞系中,SIRT4的表达显著低于癌旁组织和正常肝细胞。在体外实验中,过表达SIRT4能够明显降低肝癌细胞的成球数量(P<0.01)和干性标志物表达,并使索拉菲尼治疗的肝癌细胞克隆数和OD_(450)值进一步下降(均P<0.01)。机制研究表明,SIRT4通过去乙酰化降低谷氨酰胺合成酶2(glutamine synthase 2,GLS2)的表达,进而抑制肝癌细胞中谷氨酰胺的分解代谢,从而调节肝癌细胞的干性和对索拉菲尼的敏感性。结论:SIRT4在肝癌组织中表达显著降低,能够通过降低谷氨酰胺分解代谢,进而抑制肝癌细胞的干性并增强其对索拉菲尼的敏感性。

Multiple SiGe/Si layers epitaxy and SiGe selective etching for vertically stacked DRAM

Fifteen periods of Si/Si_(0.7)Ge_(0.3)multilayers(MLs)with various Si Ge thicknesses are grown on a 200 mm Si substrate using reduced pressure chemical vapor deposition(RPCVD).Several methods were utilized to characterize and analyze the ML structures.The high resolution transmission electron microscopy(HRTEM)results show that the ML structure with 20 nm Si_(0.7)Ge_(0.3)features the best crystal quality and no defects are observed.Stacked Si_(0.7)Ge_(0.3)ML structures etched by three different methods were carried out and compared,and the results show that they have different selectivities and morphologies.In this work,the fabrication process influences on Si/Si Ge MLs are studied and there are no significant effects on the Si layers,which are the channels in lateral gate all around field effect transistor(L-GAAFET)devices.For vertically-stacked dynamic random access memory(VS-DRAM),it is necessary to consider the dislocation caused by strain accumulation and stress release after the number of stacked layers exceeds the critical thickness.These results pave the way for the manufacture of high-performance multivertical-stacked Si nanowires,nanosheet L-GAAFETs,and DRAM devices.

黑磷夹层氧化钴纳米片构筑电催化水氧化的仿生通道

不论在自然光合作用系统中,还是在人工能量转换系统如电解水制氢、二氧化碳还原、电化学固氮和金属空气电池中,析氧反应(OER)均是一个非常重要的半反应.OER具有多电子、多质子的特性,反应过程复杂且动力学缓慢.在自然界水氧化过程中,光合系统II中的氨基酸残基构筑了专门的质子转移通道和电子转移通道,通过质子耦合电子转移来高效输运质子和电子,表现出很高的OER活性.向自然界学习,在催化剂中设计专门的质子转移通道和电子转移通道具有重要意义.本文报道了一种片状氧化钴(CoO)、黑磷(BP)和还原氧化石墨烯(RGO)杂化电催化剂,其中BP通过P–O键夹于RGO和CoO之间.广泛分布的P–O键网络构成质子受体并形成质子转移通道,起到了类似光合系统II中Asp61的质子转移作用.最内层的核层RGO作为集流体,形成电子转移通道,模拟了光合系统II中Tyr161的电荷转移功能.最外层包覆的CoO层作为水氧化反应的活性位点.X射线衍射结果表明,杂化电催化剂(CoO-BP-RGO)的衍射峰对应于六方晶系的RGO、正交晶系的BP和立方晶系的CoO.弱而宽的CoO峰表明其具有较低的结晶度和超薄纳米薄片特征.拉曼(Raman)结果表明,BP的平面结构几乎保持不变,发生的部分氧化来自于BP与CoO或GO的氧之间形成的P–O键.扫描电镜和透射电镜结果表明,BP夹在RGO和CoO纳米薄片之间,CoO的晶格条纹不连续且缺陷较多,CoO的(200)面暴露在最外层,且平行于BP和RGO平面.X射线光电子能谱(XPS)测试中,通过氩气溅射去除部分表面CoO后,P–P信号增强,进一步说明了CoO-BP-RGO样品含有BP夹层.氩气溅射后,P–O–Co信号增强,并出现了P–O–C键的信号,证明了CoO-BP-RGO杂化中P–O–Co和P–O–C键的形成.CoO-BP-RGO样品60天后的XPS分析几乎没有变化,说明CoO-BP-RGO样品在周围环境条件下非常稳定.通过计算研究表明,周围的P–O键对CoO的水氧化反应具有促进作用,羟基在CoO上的结合减弱,加速HO*的解离,在低电势下可以通过新的反应途径生成HOO*.pH依赖性实验和电化学交流阻抗实验也证实了CoO-BP-RGO中的P–O键能促进质子传导.这些特性赋予CoO-BP-RGO杂化材料较好的OER性能,电流密度达到10 mA cm^(-2),仅需206 mV过电位.该工作通过构筑专门的仿生通道,即质子转移通道和电子转移通道,加速电子和质子的转移,降低水氧化的活化能,提升催化剂的析氧性能,这为水氧化电催化剂的设计提供了新的指导.

Application of high energy X-ray diffraction and Rietveld refinement in layered lithium transition metal oxide cathode materials

Layered lithium transition metal oxide(LTMO)cathode materials have attracted much attention for lithium-ion batteries and are shining in the current market.Establishing a clear structure-performance relationship is necessary for the performance improvement of LTMO cathode materials.The combination of synchrotron X-ray diffraction(XRD)with high intensity and XRD Rietveld refinement is powerful for revealing the structural characteristics of LTMO cathode materials.This review summarizes the application of high energy XRD and Rietveld refinement in LTMO cathode materials,including the brief introduction of synchrotron XRD and Rietveld refinement and their applications in understanding the structural evolution related to the synthetic,thermal runaway,cycling,and high-rate charge/discharge process of LTMO cathode materials.Synchrotron XRD can provide insights into the intermediates and reaction paths in the synthesis process,the origin of thermal runaway,the mechanism of structural decay during cycles,and the structural evolution during high-rate charging/discharging.Future works should focus on the development of higher intensity X-rays to gain more in-depth insights into the intrinsic relationship between their structural characteristics and properties.

基于多源遥感的红树林监测

红树林是生长在热带以及亚热带海岸潮间带上的生态群落,其生产力高,固碳能力强,对保持海岸带生物多样性具有十分重要的价值。本文介绍了利用多源遥感数据监测红树林的一些主要研究内容,分为3个方面:(1)在时空模式研究方面,利用高空间分辨率影像像素和对象结合的方法对红树林树种进行分类以及利用Landsat影像对红树林进行动态变化监测并分析其驱动因素;(2)在结构参数研究方面,利用无人机多光谱数据及地面激光雷达数据对红树林叶面积指数进行反演;(3)在生理生化参数研究方面,探讨了红树林叶绿素含量对淹没状况的响应、互花米草(Spartina alterniflora)入侵是否影响红树林光能利用率,以及光化学反射指数(photochemical reflectance index,PRI)与光能利用率(light use efficiency,LUE)的关系。上述系列研究为提取红树林相关信息要素时如何选择合适的分析方法提供了有力的参考,强调了遥感在研究红树林时空模式,提取结构参数和生物生化参数监测的有效性,从而更好地促进红树林生态系统的生物多样性保育工作。

Bioelectronic protein nanowire sensors for ammonia detection

Electronic sensors based on biomaterials can lead to novel green technologies that are low cost,renewable,and eco-friendly.Here we demonstrate bioelectronic ammonia sensors made from protein nanowires harvested from the microorganism Geobacter sulfurreducens.The nanowire sensor responds to a broad range of ammonia concentrations(10 to 10^6 ppb),which covers the range relevant for industrial,environmental,and biomedical applications.The sensor also demonstrates high selectivity to ammonia compared to moisture and other common gases found in human breath.These results provide a proof-of-concept demonstration for developing protein nanowire based gas sensors for applications in industry,agriculture,environmental monitoring,and healthcare.

In-situ deposition of Pd/Pd_(4)S heterostructure on hollow carbon spheres as efficient electrocatalysts for rechargeable Li-O_(2)batteries

The sluggish kinetics of oxygen reduction reaction(ORR)and oxygen evolution reaction(OER)have always restricted the development of lithium oxygen batteries(LOBs).Herein,hollow carbon spheres loaded with Pd/Pd_(4)S heterostructure(Pd/Pd_(4)S@HCS)were successfully prepared via the in-situ deposition to improve the electrocatalytic activities for both ORR and OER in LOBs.With the welldispersed Pd/Pd_(4)S nanoparticles,the hierarchical composite with large specific surface area offers favorable transport channels for ions,electron and oxygen.Especially,the Pd/Pd_(4)S nanoparticles could exhibit excellent electrochemical performance for ORR and OER due to their intrinsic catalytic property and interfacial effect from the heterostructure.Therefore,the LOBs with Pd/Pd_(4)S@HCS as cathode catalyst show improved specific capacities,good rate ability and stable cycling performance.

Recent advances in brown adipose tissue biology

In mammals,white adipose tissue(WAT)store energy,whereas brown adipose tissue(BAT)burns energy.As a thermogenic organ,BAT can help maintain body temperature during cold exposure.Owing to its important roles in energy metabolism and regulating triacylglycerol levels,BAT has received great attention in treating obesity and its related diseases.Recent studies have suggested that BAT may secrete factor(s)—batokines—to regulate wholebody energy metabolism.In this review,we summarize the recent advances in the formation and function of BAT,as well as molecules that regulate the activity of BAT and beige fat.

An antibacterial mechanism of titanium alloy based on micro-area potential difference induced reactive oxygen species

Antimicrobial material is highly desired because of the increasing demand in biomedical application to prevent from the formation of biofilm.A common strategy for enhancing the antibacterial property of a metal material is to incorporate toxic metal such as Cu and Ag.However,the reported Cu^(2+)or Ag~+released concentration from antibacterial alloys was much less than the reported minimum inhibitory ion concentrations(MIC),revealing the existence of an unknown alternative antimicrobial mechanism not relying on the toxicity of the metal ions.Herein,we proposed a new antibacterial mechanism that the antibacterial effectiveness of the different alloys is proportional to the micro-area potential differences(MAPDs)on the surface of the alloys.We designed three kinds of Ti-M(M=Zr,Ta and Au)alloys to eliminate the potential antibacterial contribution from Cu and Ag ion.We demonstrated that high MAPDs are associated with great production of reactive oxygen species(ROS),resulting in the killing effect to the biofilm known to be associated with implant infections(Staphlococcus aureus and Escherichia coli).These results provide new insights for the design of antibacterial alloys.