纳米器件空间辐射效应机理和模拟试验技术研究进展

电子器件空间辐射效应是影响航天器在轨长期可靠运行的重要因素之一,一直是国际上抗辐射加固技术领域研究的热点和难点.高可靠、高集成度、高性能、低功耗、低成本是未来新一代先进电子系统发展的必然要求,采用更高性能的抗辐射加固纳米器件是必然的趋势.本文在深入调研国内外研究现状的基础上,分析了纳米器件辐射效应面临的新问题.纳米工艺存在着很多不同于大尺寸工艺的特点,沟道长度缩小到十几个纳米,栅氧化层等效厚度小于1 nm.在工艺上引入了纵向逆掺杂阱或横向晕环掺杂技术,以降低栅极诱导漏极漏电效应;在材料上引入了多元半导体材料、应变硅、锗硅、高k栅介质、金属栅极等,以降低器件功耗;在结构上引入了三维Fin FET结构,以增强栅的控制能力.这种趋于物理极限的工艺特点、新材料和新结构的采用产生了许多新的辐射效应现象和机制,模拟试验技术更加复杂,给抗辐射加固技术研究带来了新的挑战.本文综述了纳米器件辐射效应的研究现状和趋势,重点针对28 nm及以下特征工艺纳米器件辐射效应研究及模拟试验的需求,提出了需要研究的科学问题和关键技术,希望能为纳米器件抗辐射加固与空间应用提供参考.

Bile acid nuclear receptor FXR and digestive system diseases

Bile acids(BAs) are not only digestive surfactants but also important cell signaling molecules,which stimulate several signaling pathways to regulate some important biological processes. The bileacid-activated nuclear receptor, farnesoid X receptor(FXR), plays a pivotal role in regulating bile acid,lipid and glucose homeostasis as well as in regulating the inflammatory responses, barrier function and prevention of bacterial translocation in the intestinal tract. As expected, FXR is involved in the pathophysiology of a wide range of diseases of gastrointestinal tract, including inflammatory bowel disease, colorectal cancer and type 2 diabetes. In this review, we discuss current knowledge of the roles of FXR in physiology of the digestive system and the related diseases. Better understanding of the roles ofFXR in digestive system will accelerate the development of FXR ligands/modulators for the treatment of digestive system diseases.

Notoginsenoside Ft1 acts as a TGR5 agonist but FXR antagonist to alleviate high fat diet-induced obesity and insulin resistance in mice

Obesity and its associated complications are highly related to a current public health crisis around the world.A growing body of evidence has indicated that G-protein coupled bile acid(BA) receptor TGR5(also known as Gpbar-1) is a potential drug target to treat obesity and associated metabolic disorders.We have identified notoginsenoside Ftl(Ftl) from Panax notoginseng as an agonist of TGR5 in vitro.However,the pharmacological effects of Ftl on diet-induced obese(DIO) mice and the underlying mechanisms are still elusive.Here we show that Ftl(100 mg/100 diet) increased adipose lipolysis,promoted fat browning in inguinal adipose tissue and induced glucagon-like peptide-1(GLP-1) secretion in the ileum of wild type but not Tgr5^(-/-) obese mice.In addition,Ftl elevated serum free and taurineconjugated bile acids(BAs) by antagonizing Fxr transcriptional activities in the ileum to activate Tgr5 in the adipose tissues.The metabolic benefits of Ftl were abolished in Cyp27 al^(-/-) mice which have much lower BA levels.These results identify Ftl as a single compound with opposite activities on two key BA receptors to alleviate high fat diet-induced obesity and insulin resistance in mice.

Modeling assessment for ammonium nitrogen recovery from wastewater by chemical precipitation

Chemical precipitation to form magnesium ammonium phosphate（MAP） is an effective technology for recovering ammonium nitrogen（NH4＋-N）.In the present research,we investigated the thermodynamic modeling of the PHREEQC program for NH4＋-N recovery to evaluate the effect of reaction factors on MAP precipitation.The case study of NH4＋-N recovery from coking wastewater was conducted to provide a comparison.Response surface methodology（RSM） was applied to assist in understanding the relative significance of reaction factors and the interactive effects of solution conditions.Thermodynamic modeling indicated that the saturation index（SI） of MAP followed a polynomial function of pH.The SI of MAP increased logarithmically with the Mg2＋/NH4＋ molar ratio（Mg/N） and the initial NH4＋-N concentration（CN）,respectively,while it decreased with an increase in Ca2＋/NH4＋ and CO32？/NH4＋ molar ratios（Ca/N and CO32？/N）,respectively.The trends for NH4＋-N removal at different pH and Mg/N levels were similar to the thermodynamic modeling predictions.The RSM analysis indicated that the factors including pH,Mg/N,CN,Ca/N,（Mg/N）×（CO32？/N）,（pH）2,（Mg/N）2,and（CN）2 were significant.Response surface plots were useful for understanding the interaction effects on NH4＋-N recovery.

Bile acid signaling and bariatric surgery

The rapid worldwide rise in obesity rates over the past few decades imposes an urgent need to develop effective strategies for treating obesity and associated metabolic complications.Bariatric surgical procedures,such as Roux-en-Y gastric bypass(RYGB)and vertical sleeve gastrectomy(VSG),currently provide the most effective treatment for obesity and type 2 diabetes(T2D),as well as for non-alcoholic steatohepatitis(NASH).However,the underlying mechanisms of the beneficial effects of bariatric surgery remain elusive.Recent studies have identified bile acids as potential signaling molecules involved in the beneficial effects of bariatric surgery.This review focuses on the most recent studies on the roles of bile acids and bile acid receptors Farnesoid X receptor(FXR)and G protein-coupled bile acid receptor 5(TGR5)in bariatric surgery.We also discuss the possibility of modulating bile acid signaling as a pharmacological therapeutic approach to treating obesity and its associated metabolic complications.

Effects of La^(3+),Ce^(3+) on nitrogen removal in sequencing batch reactor

Batch experiments were conducted to study the short-term biological effects of rare earth ions(La^(3+),Ce^(3+))and their mixture on the nitrogen removal in a sequencing batch reactor(SBR).The data showed that higher NH4+–N removal rate,total inorganic nitrogen removal efficiency,and denitrification efficiency were achieved at lower concentrations of rare earth elements(REEs)(<1 mg/L).In the first hour of the aeration stage of SBR,the presence of REEs increased the total inorganic nitrogen removal efficiency and NH4+–N removal effi-ciency by 15.7%and 10%–15%,respectively.When the concentrations of REEs were higher than 1 mg/L,the total inorganic nitrogen removal efficiency decreased,and nitrate was found to accumulate in the effluent.When the concentrations of REEs was up to 50.0 mg/L,the total inorganic nitrogen removal efficiency was less than 30%of the control efficiency with a high level of nitrate.Lower concentrations of REEs were found to accelerate the nitrogen conversion and removal in SBR.

Bile acids and metabolic surgery

The epidemic of obesity and its co-mortalities has reached an alarming level worldwide.Currently,metabolic surgeries,especially the Roux-en-Y gastric bypass and vertical sleeve gastrectomy,are the most effective and sustainable treatments for obesity,type 2 diabetes,non-alcoholic steatohepatitis,as well as other metabolic diseases.However,the invasive nature of the surgeries limits their broad ap-plications to the general public.Therefore,developing alternative non-invasive approaches to mimic metabolic surgery is an important direction of the field.Recent studies have identified several potential metabolic surgery-induced downstream endocrine mediators,among which bile acids are key candidate signaling molecules.Bile acids are profoundly altered by metabolic surgery,which contributes to the metabolic effects of the surgery.In this review,we focus on the most recent studies on the roles of bile acids and bile acid receptors farnesoid X receptor and Takeda G protein-coupled receptor 5 in mediating the metabolic effects of metabolic surgery.We conclude that targeting bile acid pathways may be a promising pharmacological approach to mimic the beneficial effects of metabolic surgery.

Controlling polar-toroidal multi-order states in twisted ferroelectric nanowires

The toroidal order of electric dipoles in ferroelectric materials has attracted attention in the past decade due to fascinating properties and great potential for enabling novel memory devices,and functional devices in general.However,facile manipulation of toroidal order in ferroelectrics remains challenging.Here,using first-principles derived simulations,we demonstrate an efficient scheme to control the polar-toroidal multi-order(PTMO)states in ferroelectric nanowires.Two feasible strategies of controlling PTMO states by a combination of homogeneous electric field and torque are carried out in ferroelectric/paraelectric composite nanowires.This is possible based on trilinear coupling between polarization,toroidization and the twist force.As a result,switching of the toroidization of the nanowire can be readily achieved by reversal of the axial polarization.The torque threshold needed to control PTMO states is also calculated and found to be relatively small,indicating the feasibility of this method.Our study demonstrates facile control of PTMO states,including ferroelectric skyrmions,in ferroelectrics and is a step towards designing ferroelectric devices based on multi-order states.