3D printed ultra-fast photothermal responsive shape memory hydrogel for microrobots

Hydrogels with stimuli-responsive capabilities are gaining more and more attention nowadays with prospective applications in biomedical engineering,bioelectronics,microrobot,etc.We develop a photothermal responsive hydrogel based on N-isopropylacrylamide that achieved a fast and reversible deformation manipulated only by near-infrared(NIR)light.The hydrogel was fabricated by the projection micro stereolithography based 3D printing technique,which can rapidly prototype complex 3D structures.Furthermore,with the variation of the grayscale while manufacturing the hydrogel,the deformation of the hydrogel structure can be freely tuned within a few seconds by losing and absorbing water through adjusting the intensity and the irradiation direction of the NIR light,showing a potential application in ultra-fast object grabbing and transportation.The present study provides a new method for designing ultrafast photothermal responsive hydrogel based microrobot working in water.

Sevoflurane plays a reduced role in cognitive impairment compared with isoflurane: limited effect on fear memory retention

Isoflurane and sevoflurane are both inhalation anesthetics,but in clinical application,sevoflurane has been considered to be less suitable for long-term anesthesia because of its catabolic compounds and potential nephrotoxicity.Nevertheless,recent studies have shown that these two inhalation anesthetics are similar in hepatorenal toxicity,cost,and long-term anesthetic effect.Moreover,sevoflurane possibly has less cognitive impact on young mice.In this study,C57BL/6 mice aged 8–10 weeks were exposed to 1.2%isoflurane or 2.4%sevoflurane for 6 hours.Cognitive function and memory were examined in young mice using the novel object recognition,contextual fear conditioning,and cued-fear extinction tests.Western blot assay was performed to detect expression levels of D1 dopamine receptor,catechol-O-methyltransferase,phospho-glycogen synthase kinase-3β,and total glycogen synthase kinase-3βin the hippocampus.Our results show that impaired performance was not detected in mice exposed to sevoflurane during the novel object recognition test.Contextual memory impairment in the fear conditioning test was shorter in the sevoflurane group than the isoflurane group.Long-term sevoflurane exposure did not affect memory consolidation,while isoflurane led to memory consolidation and reduced retention.Downregulation of hippocampal D1 dopamine receptors and phosphorylated glycogen synthase kinase-3β/total glycogen synthase kinase-3βand upregulation of catechol-O-methyltransferase may be associated with differing memory performance after exposure to isoflurane or sevoflurane.These results confirm that sevoflurane has less effect on cognitive impairment than isoflurane,which may be related to expression of D1 dopamine receptors and catechol-O-methyltransferase and phosphorylation of glycogen synthase kinase-3βin the hippocampus.This study was approved by the Institutional Animal Care and Use Committee,Nanjing University,China on November 20,2017(approval No.20171102).

Effect of Mo doping on phase change performance of Sb_(2)Te_(3)

Mo,as a dopant,is doped into SbTe to improve its thermal stability.It is shown in this paper that the Mo-doped Sb_(2)Te_(3)(Mo_(0.26)Sb_(2)Te_(3),MST)material possesses phase change memory(PCM)applications.MST has better thermal stability than Sb_(2)Te_(3)(ST)and will crystallize only when the annealing temperature is higher than 250℃.With the good thermal stability,MST-based PCM cells have a fast crystallization time of 6 ns.Furthermore,endurance up to 4×10^(5) cycles with a resistance ratio of more than one order of magnitude makes MST a promising candidate for PCM applications.

Behavior recognition algorithm based on the improved R3D and LSTM network fusion

Because behavior recognition is based on video frame sequences,this paper proposes a behavior recognition algorithm that combines 3D residual convolutional neural network(R3D)and long short-term memory(LSTM).First,the residual module is extended to three dimensions,which can extract features in the time and space domain at the same time.Second,by changing the size of the pooling layer window the integrity of the time domain features is preserved,at the same time,in order to overcome the difficulty of network training and over-fitting problems,the batch normalization(BN)layer and the dropout layer are added.After that,because the global average pooling layer(GAP)is affected by the size of the feature map,the network cannot be further deepened,so the convolution layer and maxpool layer are added to the R3D network.Finally,because LSTM has the ability to memorize information and can extract more abstract timing features,the LSTM network is introduced into the R3D network.Experimental results show that the R3D+LSTM network achieves 91%recognition rate on the UCF-101 dataset.

Resistive switching memory for high density storage and computing

The resistive random access memory(RRAM)has stimulated a variety of promising applications including programmable analog circuit,massive data storage,neuromorphic computing,etc.These new emerging applications have huge demands on high integration density and low power consumption.The cross-point configuration or passive array,which offers the smallest footprint of cell size and feasible capability of multi-layer stacking,has received broad attention from the research community.In such array,correct operation of reading and writing on a cell relies on effective elimination of the sneaking current coming from the neighboring cells.This target requires nonlinear I-V characteristics of the memory cell,which can be realized by either adding separate selector or developing implicit build-in nonlinear cells.The performance of a passive array largely depends on the cell nonlinearity,reliability,on/off ratio,line resistance,thermal coupling,etc.This article provides a comprehensive review on the progress achieved concerning 3D RRAM integration.First,the authors start with a brief overview of the associative problems in passive array and the category of 3D architectures.Next,the state of the arts on the development of various selector devices and self-selective cells are presented.Key parameters that influence the device nonlinearity and current density are outlined according to the corresponding working principles.Then,the reliability issues in 3D array are summarized in terms of uniformity,endurance,retention,and disturbance.Subsequently,scaling issue and thermal crosstalk in 3D memory array are thoroughly discussed,and applications of 3D RRAM beyond storage,such as neuromorphic computing and CMOL circuit are discussed later.Summary and outlooks are given in the final.

Recognition of mortar pumpability via computer vision and deep learning

The mortar pumpability is essential in the construction industry,which requires much labor to estimate manually and always causes material waste.This paper proposes an effective method by combining a 3-dimensional convolutional neural network(3D CNN)with a 2-dimensional convolutional long short-term memory network(ConvLSTM2D)to automatically classify the mortar pumpability.Experiment results show that the proposed model has an accuracy rate of 100%with a fast convergence speed,based on the dataset organized by collecting the corresponding mortar image sequences.This work demonstrates the feasibility of using computer vision and deep learning for mortar pumpability classification.

丁苯酞对糖尿病小鼠认知功能障碍及海马N-甲基-D-天冬氨酸受体表达的影响

目的观察丁苯酞对2型糖尿病db/db小鼠学习记忆及海马N-甲基-D-天冬氨酸(NMDA)受体表达的影响,并探讨其机制。方法将16只雄性C57BL/KsJ-db/db小鼠按随机数字表法分为丁苯酞干预组[L-NBP组,予以120mg/(kg·d)丁苯酞灌胃,8只]和糖尿病对照组(DM组,等量植物油灌胃,8只),同窝出生的db/m小鼠作为正常对照组(NC组,等量植物油灌胃,10只)。干预6周后,进行指标观察。应用Morris水迷宫检测小鼠的学习记忆能力,电生理实验记录小鼠体内海马前穿通纤维-齿状回通路长时程增强(LTP)的变化,RT-PCR检测NMDA受体亚单位(NR2B)mRNA表达情况。结果与NC组比较,DM组小鼠平均逃避潜伏期延长和穿越平台次数减少(P<0.05),L-NBP组小鼠上述学习记忆成绩明显改善(P<0.05);与NC组比较,DM组和L-NBP组小鼠海马LTP明显降低[(136.17±12.73)%、(174.17±20.35)%vs(251.67±43.78)%,P<0.05],海马CA1区NR2B mRNA表达水平明显下降(1.02±0.12、1.42±0.12 vs 1.86±0.14,P<0.05)。结论丁苯酞可能通过上调糖尿病小鼠海马CA1区NMDA受体的表达,促进LTP,改善糖尿病小鼠学习记忆能力。

Improved multilevel storage capacity in Ge_(2)Sb_(2)Te_(5)-based phase-change memory using a high-aspect-ratio lateral structure

Further improvement of storage density is a key challenge for the application of phase-change memory(PCM)in storage-class memory.However,for PCM,storage density improvements include feature size scaling down and multilevel cell(MLC)operation,potentially causing thermal crosstalk issues and phase separation issues,respectively.To address these challenges,we propose a high-aspect-ratio(25:1)lateral nanowire(NW)PCM device with conventional chalcogenide Ge_(2)Sb_(2)Te_(5)(GST-225)to realize stable MLC operations,i.e.,low intra-and inter-cell variability and low resistance drift(coefficient=0.009).The improved MLC performance is attributed to the high aspect ratio,which enables precise control of the amorphous region because of sidewall confinement,as confirmed by transmission electron microscopy analysis.In summary,the NW devices provide guidance for the design of future high-aspect-ratio threedimensional PCM devices with MLC capability.

基于自注意力机制的深度学习的海洋三维温度场预测

目前主要从时空角度出发对海洋三维温度场进行预测,却忽略了相邻位置的海温相关关系。为弥补这一不足,构建一种融合了自注意力记忆模块与卷积式长短时记忆神经网络(ConvLSTM)模型的SA-ConvLSTM三维温度场预测模型,不仅可以从历史三维温度场中提取海温时空特征,还能获取并记忆相邻点位置信息,从而实现对三维温度场时空变化的把握。实验结果表明:相较于ConvLSTM模型,SA-ConvLSTM模型在滑动预测与多步长递归预测实验下的均方根误差和平均绝对误差提升约14%,且整体预测效果均优于基线模型、长短时记忆神经网络模型和ConvLSTM模型。

Novel 3D printed shape-memory PLLA-TMC/GA-TMC scaffolds for bone tissue engineering with the improved mechanical properties and degradability

The biodegradable substitution materials for bone tissue engineering have been a research hotspot.As is known to all,the biodegradability,biocompatibility,mechanical properties and plasticity of the substitution materials are the important indicators for the application of implantation materials.In this article,we reported a novel binary substitution material by blending the poly(lactic-acid)-co-(trimethylenecarbonate)and poly(glycolic-acid)-co-(trimethylene-carbonate),which are both biodegradable polymers with the same segment of flexible trimethylene-carbonate in order to accelerate the degradation rate of poly(lactic-acid)-co-(trimethylene carbonate)substrate and improve its mechanical properties.Besides,we further fabricate the porous poly(lactic-acid)-co-(trimethylene-carbonate)/poly(glycolic-acid)-co-(trimethylene-carbonate)scaffolds with uniform microstructure by the 3D extrusion printing technology in a mild printing condition.The physicochemical properties of the poly(lactic-acid)-co-(trimethylenecarbonate)/poly(glycolic-acid)-co-(trimethylene-carbonate)and the 3D printing scaffolds were investigated by universal tensile dynamometer,fourier transform infrared reflection(FTIR),scanning electron microscope(SEM)and differential scanning calorimeter(DSC).Meanwhile,the degradability of the PLLATMC/GA-TMC was performed in vitro degradation assays.Compared with PLLA-TMC group,PLLA-TMC/GATMC groups maintained the decreasing Tg,higher degradation rate and initial mechanical performance.Furthermore,the PLLA-TMC/GA-TMC 3D printing scaffolds provided shape-memory ability at 37℃.In summary,the PLLA-TMC/GA-TMC can be regarded as an alternative substitution material for bone tissue engineering.

基于当代DRAM结构的存储器控制器设计

存储器带宽以及延迟与3D架构(体、行、列)特点的DRAM芯片的存取方式紧密相关。连续访问一行的不同列与连续访问一体的不同行其带宽存在数量级的差异。本文介绍一种存储器控制器设计,一项依靠重排序存储器存取访问的顺序来挖掘3D存储器架构局部性的技术。

Neuroprotective effects of bovine colostrum on intracerebral hemorrhage-induced apoptotic neuronal cell death in rats

Brain cell death after intracerebral hemorrhage may be mediated in part by an apoptotic mechanism Colostrum is the first milk produced by mammals for their young. It plays an important role in protection and development by providing various antibodies, growth factors and nutrients, and has been used for various diseases in many countries. In the present study, we investigated the anti-apoptotic effects of bovine colostrum using organotypic hippocampal slice cultures and an intracerebral hemorrhage animal model. We performed densitometric measurements of propidium iodide uptake, a step-down avoidance task, Nissl staining, and caspase-3 immunohistochemistry. The present results revealed that colostrum treatment significantly suppressed N-methyI-D-aspartic acid-induced neuronal cell death in the rat hippocampus. Moreover, colostrum treatment improved short-term memory by suppressing hemorrhage-induced apoptotic neuronal cell death and decreasing the volume of the lesion induced by intracerebral hemorrhage in the rat hippocampus. These results suggest that colostrum may have a beneficial role in recovering brain function following hemorrhagic stroke by suppressing apoptotic cell death.

A bio-inspired 3D metamaterials with chirality and anti-chirality topology fabricated by 4D printing

Artificial architected metamaterials equipped with unique mechanical and physical properties that are naturally inaccessible can be obtained by rational design.In this work,the innovative three-dimensional(3D)chiral and anti-chiral metamaterials are developed referring to the face-rotating polyhedral(FRP)structure present in the virus.Through assembling planar triangular units into the regular octahedron cells,several typical forms of chiral and anti-chiral metamaterials can be obtained by different assembly methods.By changing the topology parameters,the Poisson’s ratio can be adjusted between[0,2.8].The metamaterials are fabricated by 3D printing utilizing shape memory polymer,and the mechanical properties are analyzed via Finite Element Analysis(FEA)and experiments,including Young’s modulus,Poisson’s ratio,and tension-twist coupling behavior.In addition,target metamaterial with specific local deformation behavior is obtained by programmatic calculations and distributions to meet special requirements or achieve unique applications.The shape memory property endows the mechanical metamaterials with more potential applications.

3D-printed NIR-responsive shape memory polyurethane/magnesium scaffolds with tight-contact for robust bone regeneration

Patients with bone defects suffer from a high rate of disability and deformity.Poor contact of grafts with defective bones and insufficient osteogenic activities lead to increased loose risks and unsatisfied repair efficacy.Although self-expanding scaffolds were developed to enhance bone integration,the limitations on the high transition temperature and the unsatisfied bioactivity hindered greatly their clinical application.Herein,we report a near-infrared-responsive and tight-contacting scaffold that comprises of shape memory polyurethane(SMPU)as the thermal-responsive matrix and magnesium(Mg)as the photothermal and bioactive component,which fabricated by the low temperature rapid prototyping(LT-RP)3D printing technology.As designed,due to synergistic effects of the components and the fabrication approach,the composite scaffold possesses a homogeneously porous structure,significantly improved mechanical properties and stable photothermal effects.The programmed scaffold can be heated to recover under near infrared irradiation in 60s.With 4 wt%Mg,the scaffold has the balanced shape fixity ratio of 93.6%and shape recovery ratio of 95.4%.The compressed composite scaffold could lift a 100 g weight under NIR light,which was more than 1700 times of its own weight.The results of the push-out tests and the finite element analysis(FEA)confirmed the tight-contacting ability of the SMPU/4 wt%Mg scaffold,which had a signficant enhancement compared to the scaffold without shape memory effects.Furthermore,The osteopromotive function of the scaffold has been demonstrated through a series of in vitro and in vivo studies.We envision this scaffold can be a clinically effective strategy for robust bone regeneration.

3D/4D Printed Functional Continuous Fiber-reinforced Polymer Composites:Progress and Perspectives

In recent years,innovations in 3D/4D printing techniques for continuous fiber-reinforced polymer composites(CFRPCs)have opened new perspectives for the integrated design and manufacture of composites with customized functions.This paper reviews the current state of 3D/4D printed functional composites,including the materi-als,shape memory/changing effects,self-monitoring/healing behaviors,and challenges surrounding additive-manufactured functional composites.Specifically,continuous fibers and matrices that provide functional roles are classified and discussed in detail.4D printed shape memory and changing CFRPCs can retain their original shapes from a designed shape upon exposure to different external stimuli,including heat,electricity,humidity,and multi-stimuli activation.Furthermore,self-monitoring of structural health is achieved through the piezore-sistive features of reinforced fibers in 3D printed CFRPCs.Finally,this review concludes with an outlook on the future research opportunities for 3D/4D printed functional CFRPCs.

A high efficiency all-PMOS charge pump for 3D NAND flash memory

For 3D vertical NAND flash memory, the charge pump output load is much larger than that of the planar NAND, resulting in the performance degradation of the conventional Dickson charge pump. Therefore, a novel all PMOS charge pump with high voltage boosting efficiency, large driving capability and high power efficiency for 3D V-NAND has been proposed. In this circuit, the Pellieoni structure is used to enhance the driving capability, two auxiliary substrate bias PMOS transistors are added to mitigate the body effect, and the degradation of the output voltage and boost efficiency caused by the threshold voltage drop is eliminated by dynamic gate control structure. Simulated results show that the proposed charge pump circuit can achieve the maximum boost efficiency of 86% and power efficiency of 50%. The output voltage of the proposed 9 stages charge pump can exceed 2 V under 2 MHz clock frequency in 2X nm 3D V-NAND technology. Our results provide guidance for the peripheral circuit design of high density 3D V-NAND integration.

一种基于共享存储的叠前深度偏移并行算法

为了解决叠前深度偏移计算量巨大这个问题,人们投入了很大精力来开发高效的并行算法.就此,在对一些相关并行算法进行分析之后,根据三维叠前Kirchhoff深度偏移的特点,提出了一种基于共享存储的简化并行算法.其中Slave进程直接存储和读取射线旅行时,消息传递总量显著减少;同时合理地结合“任务池”技术与粗粒度级并行,前者确保动态负载平衡,后者使得Slave与Master之间的通信开销尽可能小.实际教据的测试结果表明,此并行算法高效且可扩展性较好.

三维封装叠层技术

三维封装技术是一种符合电子系统轻重量、小体积、高性能、低功耗的发展趋势的先进的封装技术。本文对三维封装技术进行了简要介绍 ,重点介绍了三维封装的叠层工艺和互连技术 ,阐述了三维封装技术的优点 。

海量CT图像的激光三维信息存储结构设计

为了满足使用者对海量CT图像的存储需求,设计一种存储性能优异的海量CT图像的激光三维信息存储结构。该结构主要包括FPGA、SRAM和SDRAM三种元件,提出了信息的整体与部分存储方案,SDRAM和SRAM分别负责一级缓存和二级缓存。FPGA选择Cyclone架构的FD2C13为SDRAM提供存储配置,描述了FPGA配置连接电路图,共提供7种配置方式。为SDRAM选型MT41GO7M14C3,设计出存储结构的内部存储电路,并依次对SRAM和SDRAM进行了逻辑实现。经测试可知,所设计的存储结构存储速度快、存储完整性高、存储同步性强。