Glut-4 is translocated to both caveolae and non-caveolar lipid rafts, but is partially internalized through caveolae in insulin-stimulated adipocytes

Caveolae and non-caveolar lipid rafts are two types of membrane lipid microdomains that play important roles in insulin-stimulated glucose uptake in adipocytes. In order to ascertain their specific functions in this process, caveolae were ablated by caveolin-1 RNA interference. In Cav-1 RNAi adipocytes, neither insulin-stimulated glucose uptake nor Glut-4 （glucose transporter 4） translocation to membrane lipid microdomains was affected by the ablation of caveolae. With a modified sucrose density gradient, caveolae and non-caveolar lipid rafts could be separated. In the wild-type 3T3- L l adipocytes, Glut-4 was found to be translocated into both caveolae and non-caveolar lipid rafts. However, in Cav1 RNAi adipocytes, Glut-4 was localized predominantly in non-caveolar lipid rafts. After the removal of insulin, caveolaelocalized Glut-4 was internalized faster than non-caveolar lipid raft-associated Glut-4. The internalization of Glut-4 from plasma membrane was significantly decreased in Cav-1 RNAi adipocytes. These results suggest that insulin-stimulated Glut-4 translocation and glucose uptake are caveolae-independent events. Caveolae play a role in the internalization of Glut-4 from plasma membrane after the removal of insulin.

Lipid rafts participate in aberrant degradative autophagic-lysosomal pathway of amyloid-beta peptide in Alzheimer's disease

Amyloid-beta peptide is the main component of amyloid plaques, which are found in Alzhei- mer＇s disease. The generation and deposition of amyloid-beta is one of the crucial factors for the onset and progression of Alzheimer＇s disease. Lipid rafts are glycolipid-rich liquid domains of the plasma membrane, where certain types of protein tend to aggregate and intercalate. Lipid rafts are involved in the generation of amyloid-beta oligomers and the formation of amyloid-beta peptides. In this paper, we review the mechanism by which lipid rafts disturb the aberrant deg- radative autophagic-lysosomal pathway of amyloid-beta, which plays an important role in the pathological process of Alzheimer＇s disease. Moreover, we describe this mechanism from the view of the Two-system Theory of fasciology and thus, suggest that lipid rafts may be a new target of Alzheimer＇s disease treatment.

The contribution of attached Ulva prolifera on Pyropia aquaculture rafts to green tides in the Yellow Sea

Green tides caused by the unusual accumulation of high floating Ulva prolifera have occurred regularly in the Yellow Sea since 2007.The primary source of the Yellow Sea green tides is the attached algae on the Pyropia aquaculture rafts in the Subei Shoal.Ulva prolifera and Blidingia(Italic)sp.are the main species observed on Pyropia aquaculture rafts in the Subei Shoal.We found that U.prolifera has strong buoyancy and a rapid growth rate,which may explain why it is the dominant species of green tides that occur in the China's sea area of the Yellow Sea.The growth rate of floating U.prolifera was about 20%–31%d–1,which was much higher than Blidingia(Italic)sp.There were about 1.7×104 t of attached algae on the Pyropia aquaculture rafts in May 2012.We found that 39%of attached algae could float when the tide rose in the Subei Shoal,and U.prolifera accounted for 63%of the floating algae.Our analysis estimated that about 4000 t of attached U.prolifera floated into the surrounding waters of the Subei Shoal during the recycling period of aquaculture rafts.These results suggest that the initial floating biomass of large-scale green tides in the Yellow Sea is determined by the U.prolifera biomass attached to Pyropia aquaculture rafts,further impacting the scale of the green tide。

Involvement of Lipid Rafts and Cellular Actin in AcMNPV GP64 Distribution and Virus Budding

GP64 is the major envelope glycoprotein associated with the budded virus (BV) of Autographa californica nucleopolyhedrovirus (AcMNPV) and is essential for attachment and budding of BV particles. Confocal microscopy and flotation assays established the presence of lipid raft domains within the plasma membranes of AcMNPV-infected Sf9 cells and suggested the association of GP64 with lipid rafts during infection. GP64 and filamentous actin (F-actin) were found to co-localise at the cell cortex at 24 and 48 hpi and an additional restructuring of F-actin during infection was visualised, resulting in a strongly polarised distribution of both F-actin and GP64 at the cell cortex. Depletion of F-actin, achieved by treatment of Sf9 cells with latrunculin B (LB), resulted in the redistribution of GP64 with significant cytoplasmic aggregation and reduced presence at the plasma membrane. Treatment with LB also resulted in reduced production of BV in Sf9 cells. Analysis of virus gene transcription confirmed this reduction was not due to decreased trafficking of nucleocapsids to the nucleus or to decreased production of infectious progeny nucleocapsids. Reduced BV production due to a lack of GP64 at the plasma membrane of AcMNPV-infected Sf9 cells treated with LB, suggests a key role for F-actin in the egress of BV.

The Stability of Lipid Rafts-Like Micro-Domains Is Dependent on the Available Amount of Cholesterol

Lipid rafts are sterol and sphingolipid rich membrane domains that possibly may play roles in multiple cellular processes. These domains are still the matter of debate and it is still unknown by which mechanism if any and organisms promote their formation. This study centers on the ease of in vitro formation of lipid rafts-like structures as it relates to the relative availability of sphingolipids, phospholipids, cholesterol, and membrane proteins. Following a 12 h incubation period, isolation and extraction of the lipid rafts-like assemblies, the composition of the structures was evaluated using HPLC. Cholesterol and sphingomyelin were detected at 206 nm and phosphatidylcholine was detected at 254 nm. Identification of lactose permease, a typical membrane protein, was done using FTIR. The thermal stability of the produced structures was also determined. Results show that the addition of cholesterol significantly increased both the amount of insoluble lipid rafts-like structures and their stability, and that the availability of a minimum amount of sphingolipid was necessary to produce larger amounts of more stable structures. However, the addition of phospholipids hindered the formation of lipid rafts-like assemblies and those formed were generally less stable.

Emodin suppresses LPS-induced proinflammatory responses and nuclear factor-B activation by disruption of lipid rafts and TLR-4 recruitment in endothelial cells

Emodin [1,3,8-Trihydroxy-6-methylanthraquinone] has been reported to exhibit vascular anti-inflammatory properties.However,the relevant anti-inflammatory mechanisms are not well understood.The present study was design to explore the molecular target(s) of emodin

Energy Absorption by the Membrane Rafts in the Modulated Electro-Hyperthermia (mEHT)

Aim: Heating by nanoparticles, which are located in the tissue to be treated, is a well-recognized method in hyperthermic oncology. Our objective is to investigate selective, nanoscopic heating without concentrating extra artificial nanoparticles. We have in silico calculation to study the heating of the transmembrane protein clusters (rafts) on cell-membrane. The transmembrane protein domains have significantly higher dielectric constant than their lipid neighborhood in the membrane. This difference causes a local gradient in the Specific Absorption Rate (SAR), which could be a factor of heating of the membranes locally, as well as exciting the receptors for various signal transduction in the cells. We suppose that this process determines the observed cellular effects of modulated electro-hyperthermia (mEHT, trade-name: oncothermia). Materials and Methods: In silico models with highly specialized software (Computer Simulation Technology (CST), Darmstadt, Germany) were performed visualizing the selectivity for the membrane domains. Local raft models were created to simulate the electromagnetic (EM) effect of a 13.56 MHz excitation between two perfect electrical conductor plates, simulating the equipotential conditions of the sides of the membrane in the vicinity of the raft. The simulations were performed with near-field (EQS) solver of CST. The electric field, current density, and electric loss density were monitored by the simulations. The applied material properties and parameters refer to the recent literature. Results: In silico models show ten times higher energy-absorption of the transmembrane domains than that of its lipid-membrane surrounding, and intra- and extracellular neighborhood. Depending on the size, orientation, and location of the membrane rafts, the value of SAR varies, but we use only two simplified models to see the absorption properties. Taking into account the characteristics of the EM field effects we showed that the selective energy-absorption increased further by the cell-cell interactions. The model-calculation could confirm the opportunity of the local membrane heating. Conclusion: Our results indicate the heating in nanoscopic range with energy-absorption by the transmembrane proteins. The heated protein-clusters (membrane rafts) are used the same way as the artificial nanoparticles, while these absorbers are natural parts of the biological system.

Dynamics of Submersible Mussel Rafts in Waves and Current

To investigate the dynamics of submersible mussel rafts, the finite element program Aqua-FETM, developed by the University of New Hampshire（UNH）, was applied to rafts moored at the surface and submerged. The submerged configuration is used to reduce wave forcing and to avoid contact with floating ice during winters in northern waters. Each raft consists of three pontoons connected by a grid framework. Rafts are intended to support densely spaced mussel ropes hung from the framework. When submerged, the pontoons are flooded, and the raft is held vertically by floats attached by lines. The computer models were developed in Aqua-FE？ to simulate the effects of waves and current. They were validated by comparison with wave tank results by use of a 1/10 scale raft physical model. Comparisons showed good agreement for the important heave（vertical） and pitch（rotational） motions, though there was a tendency towards conservative results for wave and current drag. Full-scale simulations of surface and submerged single raft and two rafts connected in tandem were performed. Submerged raft wave response was found to be reduced relative to that at the surface for both the single and two-raft configurations. In particular, the vertical motion of mussel rope connection points was significantly reduced by submergence, resulting in reduced potential for mussel drop-off. For example, the maximum vertical velocities of mussel rope attachment points in the submerged two raft case were 7%-20% of the corresponding velocities when at the surface.

Deep Foundation Pit Excavations Adjacent to Disconnected Piled Rafts: A Review on Risk Control Practice

Foundation pit excavation engineering is an old subject full of decision making. Yet, it still deserves further research due to the associated high failure cost and the complexity of the geological conditions and/or the surrounding existing infrastructure around it. This article overviews the risk control practice of foundation pit excavation projects in close proximity to existing disconnected piled raft. More focus is given to geotechnical aspects. The review begins with achievements to ensure excavation performance requirements, and follows to discuss the complex soil structure interaction involved among the fundamental components: the retaining wall, mat, piles, cushion, and the soil. After bringing consensus points to practicing engineers and decision makers, it then suggests possible future research directions.

基于日志副本的Raft共识算法优化

在基于三副本策略的分布式存储系统中,当存储节点上的硬盘出现故障时,常见的处理方式是等待系统预设的时间.如果该故障硬盘超时未恢复,才开始恢复故障硬盘上的副本.这种处理方式存在的问题是,当三副本组中存在故障副本时,如果该副本组再有一个副本所在的硬盘发生故障,将导致系统无法继续提供服务,且不能自动恢复.本文提出一种基于日志副本的改进的Raft共识算法,即LR-Raft (log replica based Raft),日志副本没有完整状态机,可以快速加入集群,并参与投票与共识,提升了存在故障硬盘时系统的可用性;可以解决短时间内三副本中两个副本故障导致集群不可用和丢失数据的问题.实验结果表明,在副本组中引入日志副本后,与原Raft相比,LR-Raft在不同的工作负载下读写时延均明显降低,吞吐量显著提升.

基于Raft的多主节点拜占庭容错共识机制

为了解决联盟链中实用拜占庭容错(PBFT)共识机制在区块链网络中节点数量增多的情况下,通信复杂度高、共识效率低下等问题,本文提出一种基于Raft的多主节点拜占庭容错共识机制IMRBFT。IMRBFT通过Maglev一致性哈希算法对区块链网络节点均匀分组,将这个共识流程分成组外共识和组内共识2部分。组内先选出领导者节点,通过信用机制将节点分为3个等级:可信节点、普通节点和不可信节点。与投票机制共同降低恶意节点成为领导者节点的概率,并与其他组的领导者节点组成委员会,委员会再经过组外信用值机制选出信用值最高的多个主节点进行组外PBFT共识。组内共识在Raft共识的基础上引入监管节点与中继节点,进一步提升安全性与共识效率,减少恶意节点的作恶行为。实验结果表明:IMRBFT的通信开销为线性增长,通信量为PBFT的41.6%,吞吐量为PBFT的4.2倍,共识延时降低76.4%。随着节点增多,优化更加明显,完全满足大型区块链网络的通信复杂度小、吞吐量高、共识延时短、安全性与共识效率高的要求。

基于联盟链微电网交易的改进Raft共识算法

针对联盟链微电网交易场景的高吞吐量与抵御拜占庭节点攻击的需求,提出了一种基于Raft的多领导者拜占庭容错共识算法MLB-Raft(multi-leader Byzantine fault tolerance-Raft)。首先使用可验证随机函数VRF选举领导者节点群,通过多领导者并行提交区块的方式提高算法的吞吐量;接着引入了协调者角色,负责领导者的选举、管理与系统共识;在领导者与跟随者进行区块复制的过程中,结合并简化了PBFT算法的共识流程,实现本算法的抗拜占庭特性。实验结果表明,在大规模网络节点环境下,相较于Raft算法,该算法提高了吞吐量与共识效率,但付出了部分通信开销代价;相较于PBFT算法,该算法提高了拜占庭容错能力,降低了通信开销。综上,该算法能有效保障联盟链微电网交易的时效性与安全性。

基于Rs-BasicVSR的煤机装备视频超分辨率算法

煤矿井下煤机装备搭载的摄像仪传输的视频信息存在信号干扰,分辨率低,细节缺失等问题,对后续的视频智能分析有着极大挑战。针对该问题,提出一种基于Rs-Basic VSR的煤机装备视频超分辨率算法。首先,在光流对齐部分改用RAFT网络,通过对图像特征建立相关空间,并根据特征信息进行搜索,提升光流计算精度;接着对网络结构进行裁剪,减少卷积层个数。实验结果表明,该算法在平均PSNR上可达31.83 dB,SSIM上达到了0.8919,平均推理时间为60 ms,模型参数量为5.9×10~6,主观视觉效果和客观指标上可以满足煤矿井下视频处理需求。

有机硅基RAFT试剂制备聚醚改性有机硅消泡剂

以八甲基环四硅氧烷和巯丙基甲基二甲氧基硅烷为原料,合成了巯基硅油;再以巯基硅油、CS_(2)和2-溴代异丁酸甲酯为原料,合成了有机硅基可逆加成-断裂链转移(RAFT)试剂(RAFT-SSO);RAFT-SSO与甲基封端的烯丙基聚氧乙烯醚(EO)、甲基封端的烯丙基聚氧丙烯醚(PO)采用RAFT聚合反应合成了聚醚改性有机硅消泡剂(RS-EOPO)。采用FTIR、^(1)HNMR,GPC对RS-EOPO进行了结构表征,对其消泡、抑泡、相容性进行了测试,并将RS-EOPO与进口消泡剂性能进行对比。RS-EOPO最佳合成工艺条件为RAFT-SSO相对分子质量为2000、m(EO)∶m(PO)=1∶4、m(RAFT-SSO)∶m〔醚(EO和PO)〕=1∶1.15、反应温度75℃、反应时间8 h、引发剂用量为EO(3.45 g)和PO总质量的2%。在上述条件下,RS-EOPO收率为91.8%。

面向RAFT共识的低能耗无线区块链分片算法

区块链系统由于共识协商需要多轮沟通,会消耗大量的能量。在一些无线网络中,节点电池容量有限,会迅速导致节点能量耗尽和脱机,从而影响共识性能。该文设计了一种面向RAFT共识的低能耗的分片算法,算法将无线区块链网络中的节点限制在基于地理区域的分片上,从而避免节点参与全局共识。同时,还提出了一种分片后的能耗估算方法,简化了分片无线区块链网络的能量计算。在太赫兹和毫米波两个信号场景中得到的仿真结果均验证了该算法的有效性,能耗可降低98.36%,估算方法的最小误差仅为0.40%。

低临界胶束浓度PEGMA-b-PCL的制备及其药物缓释性能

以ε-己内酯(ε-CL)为疏水链段、聚乙二醇甲醚甲基丙烯酸酯(PEGMA)为亲水链段、4-氰基-4-[(十二烷基硫烷基硫代羰基)硫烷基]戊醇(CDPA)为可逆加成-断裂链转移(RAFT)试剂、甲苯为溶剂,在N_(2)氛围、80℃、反应24 h的条件下,通过RAFT聚合法制备了两嵌段共聚物(PEGMA-b-PCL)。将其自组装为胶束,作为纳米药物载体用于负载姜黄素(Cur)。采用FTIR、^(1)HNMR、GPC、SEM、DLS对PEGMA-b-PCL进行了表征,测试了胶束载体的载药和释药性能。结果表明,两嵌段共聚物数均相对分子质量范围为1478~7318,其具有较低的临界胶束浓度(在pH=5.0~7.4,范围为0.920~1.600 mg/L)。胶束载体粒径范围为68.34~186.93 nm。当n(CDPA)∶n(ε-CL)=1∶200时,胶束载药率和包封率最高,可达12.05%±0.29%和75.26%±2.41%。在不同pH环境下,药物缓释性能可达15 d,其中pH=5.0时的累积释药率最高,可达38.20%。

水相RAFT聚合合成中低相对分子质量窄分布聚丙烯酰胺

为开发一种高效的RAFT试剂和简便的合成相对分子质量较高的窄分布聚丙烯酰胺的方法,合成了一种新型的可控/活性聚合链转移剂(RAFT试剂)1,4-苄基三硫代碳酸酯基二丙酸,该RAFT试剂在热引发或光引发条件下,引发活性可控水溶液聚合反应合成了窄分布的低相对分子质量及中等相对分子质量聚丙烯酰胺,且分散系数Mw/Mn<1.1。通过改变单体[M]0/链转移剂[CTA]0/引发剂进料比([M]0/[CTA]0/[I]0)合成了不同相对分子质量的窄分布的聚丙烯酰胺,相对分子质量最高可达5.0×10^(6)。聚丙烯酰胺相对分子质量及分散系数由凝胶渗透色谱-18角度激光散射仪测定。

基于改进Raft共识算法和PBFT共识算法的双层共识算法

针对目前应用于联盟链中的实用拜占庭(PBFT)共识算法可扩展性不足、通信开销增长过大、难以适用于大规模网络节点环境等问题,提出了一种基于改进Raft共识算法和PBFT共识算法的双层共识算法(DL_RBFT)。首先将区块链中的节点分成若干小组,组成下层共识网络,然后小组的组长再构成上层共识网络,形成一个双层共识网络结构;在下层共识网络的小组内部引入监督机制和声誉机制来改进Raft共识算法,在初始组长的选举流程引入了蚁群算法,使选举效率始终维持在较高水平;在上层共识网络中,使用PBFT共识算法进行共识。改进后的Raft共识算法具备了抗拜占庭节点攻击的能力,提升了算法的安全性。实验结果分析表明,相较于传统的PBFT共识算法,在100个节点的情况下,DL_RBFT将共识时延降低了两个数量级,吞吐量也提升了一个数量级,与其余改进算法相比也有着明显优势。因此DL_RBFT共识算法拥有良好的可扩展性,可以广泛应用于联盟链的各种场景中。

基于Raft共识协议的分布式键值对存储系统研究与实现

针对工业物联网、大数据等领域对分布式数据存储基础设施提出的高性能、高可用性和高可靠性需求,简要回顾和分析了分布式共识协议的相关理论与关键技术,研究了具有高性能、高可用性和高可靠性的分布式键值对存储系统,并设计开发了基于Raft共识协议和LevelDB的分布式键值对存储系统。最后,测试了该系统的功能和性能指标。实验结果表明,该系统具有高稳定性、高可用性和良好的性能。

连续管式反应器中降黏型聚羧酸减水剂的合成及性能

以异戊烯醇聚氧乙烯聚氧丙烯醚(IPEPPG)、2-甲基-2-(丁基三硫代碳酸酯基)丙酸(BTMP)和马来酸酐为主要反应原料,在连续管式反应器中利用热引发可逆加成-断裂链转移(RAFT)聚合,合成了1种窄相对分子质量分布的降黏型聚羧酸减水剂VR-PCE-TR。采用1HNMR、FTIR和GPC对VR-PCE-TR进行了表征,考察VR-PCE-TR对混凝土的工作性能和流变性能的影响,并与釜式反应器中采用常规水相自由基聚合制备的降黏型聚羧酸减水剂进行了性能对比。结果表明,当减水剂溶液质量分数为10%时,VR-PCE-TR具有最低表面张力(30.65 mN/m);当减水剂质量分数为0.8%时,VR-PCE-TR对水泥颗粒具有更高的吸附量(2.803 mg/g);在减水剂掺量(以水泥质量计,下同)0.13%时,掺加VR-PCE-TR后的水泥浆体具有更好的分散性和分散保持性;当减水剂掺量为0.4%时,掺加VR-PCE-TR后的水泥净浆具有更小的屈服应力(1.3 Pa)和更低的塑性黏度(0.26 Pa·s)。连续管式反应器避免了物料除氧步骤,能够保持聚合控制性和聚合反应速率,因此,制备的VR-PCE-TR具有更窄的相对分子质量分布(多分散性指数为1.19),进而有更好的降黏效果和应用性能。