Advances in neuromorphic computing:Expanding horizons for AI development through novel artificial neurons and in-sensor computing

AI development has brought great success to upgrading the information age.At the same time,the large-scale artificial neural network for building AI systems is thirsty for computing power,which is barely satisfied by the conventional computing hardware.In the post-Moore era,the increase in computing power brought about by the size reduction of CMOS in very large-scale integrated circuits(VLSIC)is challenging to meet the growing demand for AI computing power.To address the issue,technical approaches like neuromorphic computing attract great attention because of their feature of breaking Von-Neumann architecture,and dealing with AI algorithms much more parallelly and energy efficiently.Inspired by the human neural network architecture,neuromorphic computing hardware is brought to life based on novel artificial neurons constructed by new materials or devices.Although it is relatively difficult to deploy a training process in the neuromorphic architecture like spiking neural network(SNN),the development in this field has incubated promising technologies like in-sensor computing,which brings new opportunities for multidisciplinary research,including the field of optoelectronic materials and devices,artificial neural networks,and microelectronics integration technology.The vision chips based on the architectures could reduce unnecessary data transfer and realize fast and energy-efficient visual cognitive processing.This paper reviews firstly the architectures and algorithms of SNN,and artificial neuron devices supporting neuromorphic computing,then the recent progress of in-sensor computing vision chips,which all will promote the development of AI.

Control of GaN inverted pyramids growth on c-plane patterned sapphire substrates

Growth of gallium nitride(GaN)inverted pyramids on c-plane sapphire substrates is benefit for fabricating novel devices as it forms the semipolar facets.In this work,GaN inverted pyramids are directly grown on c-plane patterned sapphire substrates(PSS)by metal organic vapor phase epitaxy(MOVPE).The influences of growth conditions on the surface morphol-ogy are experimentally studied and explained by Wulff constructions.The competition of growth rate among{0001},{1011},and{1122}facets results in the various surface morphologies of GaN.A higher growth temperature of 985 ℃ and a lowerⅤ/Ⅲratio of 25 can expand the area of{}facets in GaN inverted pyramids.On the other hand,GaN inverted pyramids with almost pure{}facets are obtained by using a lower growth temperature of 930℃,a higherⅤ/Ⅲratio of 100,and PSS with pattern arrangement perpendicular to the substrate primary flat.

Photonics-assisted THz wireless communication enabled by wide-bandwidth packaged backilluminated modified uni-traveling-carrier photodiode

This paper presents a wide-bandwidth back-illuminated modified uni-traveling-carrier photodiode(MUTC-PD)packaged with standard WR-5 rectangular waveguide for high-speed wireless communications.With optimized epitaxy structure and coplanar waveguide electrodes,the fabricated 4-μm-diameter PD exhibits ultra-flat frequency response and high saturation power.Integrated passive circuits including low-loss bias-tee and E-plane probe are designed to package the PD into a compact module with waveguide output.The packaged PD module has demonstrated a flat frequency response with fluctuations within±2.75 d B over a broadband of 140–220 GHz and a high saturated output power of-7.8 d Bm(166μW)at 140 GHz.For wireless communication applications,the packaged PD is used to implement 1-m free space transmission at carrier frequencies of 150.5 and 210.5 GHz,with transmission rates of 75 and 90 Gbps,respectively.

含氟及苯环侧基的聚酰亚胺材料的制备及表征

由4-甲氧基二苯甲酮通过McMurry偶联反应得到(E)-1-甲氧基-4-(2-(4-甲氧基苯基)-1,2-二苯基乙烯基)苯(1),经过脱甲基,与邻氯对硝基三氟甲基苯进行亲核取代并还原得到(E)-4-(4-(2-(4-(4-氨基-2-三氟甲基苯氧基)苯基)-1,2-二苯基)苯氧基)-3-三氟甲基苯胺(APBA);采用上述二胺单体与4,4'-氧双邻苯二甲酸酐(ODPA)进行二元共聚,与4,4'-二氨基二苯醚(ODA)、ODPA按摩尔比15:85:100,45:55:100,75:25:100进行三元共聚,得到4种聚酰亚胺(PI)树脂及薄膜。然后对所得PI的结构、耐热性能、荧光性能、溶解性、吸水率等进行表征。研究结果表明,4种聚酰胺酸的特性黏度在0.91~1.91 dL/g之间,PI树脂在N,N-二甲基甲酰胺(DMF)、N,N-二甲基乙酰胺(DMAc)、间甲酚中都有不错的溶解性,在氯仿、四氢呋喃、二甲亚砜中的溶解性随着APBA含量的增加而增加;同时吸水率不断减低,分别为1.12%,0.68%,0.62%和0.39%;5%的热失重均在300℃以上,且稳定性随APBA含量的增加而增加,完全降解温度达到了630℃;另外,四苯乙烯型化合物的引入提高了荧光寿命,使其由单体的4.96 ns延长到了13.24 ns。

Accelerating Packet Classification with Counting Bloom Filters for Virtual Open Flow Switching

The growing trend of network virtualization results in a widespread adoption of virtual switches in virtualized environments. However, virtual switching is confronted with great performance challenges regarding packet classification especially in Open Flow-based software defined networks. This paper first takes an insight into packet classification in virtual Open Flow switching, and points out that its performance bottleneck is dominated by flow table traversals of multiple failed mask probing for each arrived packet. Then we are motivated to propose an efficient packet classification algorithm based on counting bloom filters. In particular, counting bloom filters are applied to predict the failures of flow table lookups with great possibilities, and bypass flow table traversals for failed mask probing. Finally, our proposed packet classification algorithm is evaluated with real network traffic traces by experiments. The experimental results indicate that our proposed algorithm outperforms the classical one in Open v Switch in terms of average search length, and contributes to promote virtual Open Flow switching performance.

Studies on the nucleation of MBE grown Ⅲ-nitride nanowires on Si

GaN and AlN nanowires（NWs） have attracted great interests for the fabrication of novel nano-sized devices. In this paper, the nucleation processes of GaN and AlN NWs grown on Si substrates by molecular beam epitaxy（MBE）are investigated. It is found that GaN NWs nucleated on in-situ formed Si3N4 fully release the stress upon the interface between GaN NW and amorphous Si3N4 layer, while AlN NWs nucleated by aluminization process gradually release the stress during growth. Depending on the strain status as well as the migration ability of Ⅲ group adatoms, the different growth kinetics of GaN and AlN NWs result in different NW morphologies, i.e., GaN NWs with uniform radii and AlN NWs with tapered bases.

基于光子混频的140∼220 GHz噪声发生器

本文提出并实现了一种利用超宽带光探测器进行光子混频的太赫兹噪声发生器.通过改进外延结构和电极结构,首次在国内实现3 dB带宽超过200 GHz的单行载流子光电探测器(uni-travelingcarrier photodiode,UTC-PD).封装后的UTC-PD模块可在140∼220 GHz频段内实现平坦的太赫兹波输出.利用该探测器模块作为光混频器制作了光子噪声发生器,产生了频率范围为140∼220 GHz,超噪比(excess noise ratio,ENR)大于35 dB,平坦度小于±4.6 dB的太赫兹噪声,并且可以通过调节输入光功率实现超噪比的调谐.

Double-cliff-layer uni-traveling-carrier photodiode with high responsivity and ultra-broad bandwidth

A novel backside-illuminated double-cliff-layer uni-traveling-carrier(DCL-UTC)photodiode with both high responsivity and ultra-broad bandwidth is designed and demonstrated.A thick absorption layer is adopted for high responsivity,and a depletion region with double cliff layers is proposed to alleviate the space charge effect and maintain overshoot electron velocity under large photocurrents.In addition,inductive coplanar waveguide electrodes are employed to enhance the frequency response performance.The 6-μm-diameter photodiode exhibits a high responsivity of 0.51 A/W and a large 3-dB bandwidth of 102 GHz.A high RF output power of 2.7 dBm is recorded at 100 GHz.

Development and validation of an immunogenic cell death-related prognostic model, and landscape of the tumor immune microenvironment in glioblastoma

The important role of immunogenic cell death(ICD)in many tumors is increasingly being discovered.However,its mechanisms and potential as a biomarker and therapeutic target in glioblastoma(GBM)have not been well studied.We obtained GBM samples from the Cancer Genome Atlas(TCGA)and Gene Expression Omnibus(GEO)databases,as well as the immunotherapy cohort from the IMvigor210 study.We used unsupervised clustering to obtain two ICDrelated clusters,corresponding to the ICD-low and ICD-high subtypes respectively,and the tumor immune microenvironment and prognosis of the two subtypes were significantly different.

GaN基材料的低温外延技术

GaN基半导体材料的禁带宽度覆盖了整个可见光波段,且其具有优良的物理化学特性,因而被广泛应用于光电子器件、电力电子器件及射频微波器件的制备.传统的GaN基材料通常是利用金属有机物化学气相沉积、分子束外延或氢化物气相外延等在蓝宝石、硅或碳化硅等耐高温的单晶衬底上外延生长得到.这些外延生长技术通常采用高温来裂解参与反应的前驱体.随着信息化和智能化的变革不断深入,催生出了对核心光(电)子器件的低成本和柔性化等共性需求.廉价且易于大面积制备的非晶衬底(玻璃、塑料、金属、聚对苯二甲酸乙二醇酯(polyethylene terephthalate,PET)、聚二甲基硅氧烷(polydimethylsiloxane,PDMS)等)是较为理想的选择,但非晶衬底的一个显著缺点是不能耐受较高的生长温度.由此催生出了GaN基材料低温外延的需求,即需要一类在低温下可以利用外电场能量裂解反应前驱体的外延设备.到目前为止,人们基于物理气相沉积和化学气相沉积的基本原理已经开发出了多种低温外延技术,取得了初步的研究结果.本文分别对这两类低温外延技术进行详细介绍,包括设备结构、工作条件和相关的外延生长结果,总结各类技术的特点.最后,对低温外延技术的发展前景作了展望,指出未来研究需要关注的重点.

低电负性阴离子掺杂调控钴酸锌的电子结构以提高析氧反应活性

电子结构和电导率是析氧反应活性的重要描述符,它们可以通过掺杂来调节.鉴于金属掺杂通常会减少电催化剂的活性位点数量,本工作探究了阴离子掺杂对尖晶石钴酸锌(ZCO)电子结构及其析氧活性的影响.与三价钴为主的ZCO相比,用电负性较低的硫取代氧会提高低自旋态(t_(2g)-^(6)e_(g)^(1))二价钴的占比,其析氧活性要高于低自旋态的三价钴(t_(2g)-^(6)e_(g)^(0)).掺硫钴酸锌(ZCO-S)中钴离子和阴离子之间的电子密度的再分布导致了二价钴的增多,而且钴和硫离子间的强共价作用也会加速电荷迁移.ZCO-S在1.65伏(相对于可逆氢电极)下的比活性比原始ZCO高11倍.相反,掺入具有较高电负性和价态的氟(F)并不能有效地改善电子结构,最终导致材料析氧活性的降低.本工作建立了所掺阴离子的电负性与钴酸锌本征析氧活性之间的联系,并提供了一种通过掺杂不同电负性的阴离子来调控尖晶石氧化物的电子结构的简单有效的方法,这为合理设计高性能尖晶石电催化剂提供了新途径.

面向柔性光电子器件的低温外延技术

柔性光电子器件需要在金属、玻璃、塑料等柔性非单晶衬底上制作或承载光电转换薄膜,已有的实现柔性光电子器件的方法分为两大类:直接在非单晶衬底上沉积有机光电转换薄膜;或者将外延生长的无机光电转换薄膜从单晶衬底转移到非单晶衬底.前者无法在柔性非单晶衬底上制作无机光电子器件,后者存在大面积转移的困难.如果能够在非单晶的柔性衬底上直接外延生长无机光电子器件,将为柔性无机光电子器件开辟一条新的技术路线和研究方向.传统的无机光电子器件的外延生长通常需要足够高的外延生长温度和耐高温的单晶衬底,前者裂解反应物并向其提供原子表面迁移能力,后者提供无机光电转换薄膜的晶格排列方式.通过电磁场耦合降低外延生长所需的温度,则有可能在柔性非单晶衬底上直接外延生长无机光电子薄膜.本文综合分析了国际上的低温外延技术的研究现状,并着重介绍了本研究团队提出的低温外延方法——电感应耦合等离子体金属有机物化学气相外延(inductive coupled plasma metal organic vapor phase epitaxy,ICP-MOVPE),包括ICP-MOVPE的设计思路、反应腔内等离子体的模拟仿真和该设备进行III族氮化物半导体外延生长的初步结果.

Tetrahydroisoquinolines as novel histone deacetylase inhibitors for treatment of cancer

Histone acetylation is a critical process in the regulation of chromatin structure and gene expression.Histone deacetylases(HDACs)remove the acetyl group,leading to chromatin condensation and transcriptional repression.HDAC inhibitors are considered a new class of anticancer agents and have been shown to alter gene transcription and exert antitumor effects.This paper describes our work on the structural determination and structure-activity relationship(SAR)optimization of tetrahydroisoquinoline compounds as HDAC inhibitors.These compounds were tested for their ability to inhibit HDAC 1,3,6 and for their ability to inhibit the proliferation of a panel of cancer cell lines.Among these,compound 82 showed the greatest inhibitory activity toward HDAC 1,3,6 and strongly inhibited growth of the cancer cell lines,with results clearly superior to those of the reference compound,vorinostat(SAHA).Compound 82 increased the acetylation of histones H3,H4 and tubulin in a concentration-dependent manner,suggesting that it is a broad inhibitor of HDACs.

Discovery of a series of dimethoxybenzene FGFR inhibitors with 5H-pyrrolo[2,3-b]pyrazine scaffold: structure–activity relationship, crystal structural characterization and in vivo study

Genomic alterations are commonly found in the signaling pathways of fibroblast growth factor receptors(FGFRs). Although there is no selective FGFR inhibitors in market, several promising inhibitors have been investigated in clinical trials, and showed encouraging efficacies in patients. By designing a hybrid between the FGFR-selectivity-enhancing motif dimethoxybenzene group and our previously identified novel scaffold, we discovered a new series of potent FGFR inhibitors, with the best one showing sub-nanomolar enzymatic activity. After several round of optimization and with the solved crystal structure, detailed structure–activity relationship was elaborated. Together with in vitro metabolic stability tests and in vivo pharmacokinetic profiling, a representative compound(35) was selected and tested in xenograft mouse model, and the result demonstrated that inhibitor 35 was effective against tumors with FGFR genetic alterations, exhibiting potential for further development.

Wideband thin-film lithium niobate modulator with low half-wave-voltage length product

A novel thin-film lithium niobate(TFLN) electro-optic modulator is proposed and demonstrated. LiNbO_(3)-silica hybrid waveguide is adopted to maintain low optical loss for an electrode spacing as narrow as 3 μm, resulting in a low halfwave-voltage length product of only 1.7 V·cm. Capacitively loaded traveling-wave electrodes are employed to reduce the microwave loss, while a quartz substrate is used in place of a silicon substrate to achieve velocity matching. The fabricated TFLN modulator with a 5-mm-long modulation region exhibits a half-wave voltage of 3.4 V and a merely less than 2 d B roll-off in an electro-optic response up to 67 GHz.

Design method for hypersonic bump inlet based on transverse pressure gradient

Transverse pressure gradient(TPG)is one of the key factors influencing the boundary layer airflow diversion in a bump inlet.This paper proposes a novel TPG-based hypersonic bump inlet design method.This method consists of two steps.First,a parametric optimization approach is employed to design a series of 2D inlets with various compression efficiencies.Then,according to the prescribed TPG,the optimized inlets are placed in different osculating planes to generate a 3D bump inlet.This method provides a means to directly control the aerodynamic parameters of the bump rather than the geometric parameters.By performing this method to a hypersonic chin inlet,a long and wide bump surface is formed in the compression wall,which leads to good integration of the bump/inlet.Results show that a part of the near-wall boundary layer flow is diverted by the bump,resulting in a slight decrease in the mass flow but a significant improvement in the total pressure recovery.In addition,the starting ability is significantly improved by adding the bump surface.Analysis reveals that the bump has a 3D rebuilding effect on the large-scale separation bubble of the unstarted inlet.Finally,a mass flow correction is performed on the designed bump inlet to increase the mass flow to full airflow capture.The results show that the mass flow rate of the corrected bump inlet reaches up to 0.9993,demonstrating that the correction method is effective.

Laser annealing of SiO2 film deposited by ICPECVD for fabrication of silicon based low loss waveguide

Laser annealing of silicon dioxide （SiO2） film formed by inductively coupled plasma enhanced chemical vapor deposition （ICPECVD）is studied for the fabrication of low loss silicon based waveguide. The influence of laser annealing on ICPECVD-deposited SiO2 film is investigated. The surface roughness, refractive index, and etch rate of annealed samples are compared with those of SiO2 film obtained by thermal oxidation. It is demonstrated that the performance of ICPECVD-deposited SiO2 film can be significantly improved by laser annealing. Al2O3/SIO2 waveguide has been fabricated on silicon substrate with the SiO2 lower cladding formed by ICPECVD and laser annealing process, and its propagation loss is found to be comparable with that of the waveguide with thermally oxidized lower cladding.

Dynamic changes of serum cholinesterase activity after severe trauma

Objective： The aim of the present study was to examine dynamic changes in serum cholinesterase （ChE） activity during early-stage severe trauma and the clinical significance of these changes. Methods： This prospective, observational study included 81 patients with severe trauma who were treated between October 2011 and April 2013 in the emergency intensive care unit （EICU） of a university-affiliated, tertiary-care, grade A general hospital in China. Serum ChE activity was measured on Days 1, 3, and 7 post-injury. The correlation of dynamic changes in serum ChE activity with trauma severity and prognosis was assessed. Correlations between changes in serum ChE activity after injury and albumin （ALB）, prealbumin （PAB）, transferrin （TRF）, and C-reactive protein （CRP） levels were also analyzed Results： Serum ChE activity in trauma patients was 42.3%-50.2% lower on Days 1, 3, and 7 compared with the control （P〈0.001 for all time points）, and it continued to decrease after Day 7 in both the survival and death subgroups. In the subgroup with an injury severity score （ISS） of 〈25, serum ChE activity initially decreased, but eventually increased. However, activity decreased continuously in the ISS〉25 subgroup. ChE activity was significantly lower in both the death and the ISS〉25 subgroups than in the survival and ISS〈25 subgroups on Days 1, 3, and 7 after injury. Activity was negatively correlated with ISS and acute physiology and chronic health evaluation Ill （APACHE III） at all time points. When comparing the receiver operating characteristic （ROC） curves for predicting prognosis, the area under the curve （AUC） in the dot of serum ChE was similar to the AUCs in plots of ISS and APACHE Ⅲ, but significantly smaller than the AUC in the plot of the trauma and injury severity score （TRISS）. Serum ChE activity was positively correlated with ALB, PAB, and TRF at all time points post-injury. Activity was not significantly correlated with CRP on Day 1, but was significantly and negatively correlated with CRP on Days 3 and 7. Conclusions： There is a significant decrease in serum ChE activity after severe trauma. Serum ChE may be regarded as a negative acute phase protein （APP） and the dynamic changes in serum ChE may be useful as an auxiliary indicator for evaluating trauma severity and predicting prognosis.

Discovery of 4-cyclopropyl-3-(2-((1-cyclopropyl-1H-pyrazol-4-yl) amino) quinazolin-6-yl)-N-(3-(trifluoromethyl) phenyl) benzamides as potent discoidin domain receptor inhibitors for the treatment of idiopathic pulmonary fibrosis

Idiopathic pulmonary fibrosis(IPF)is a chronic fatal lung disease with a median survival time of 3–5 years.Inaccurate diagnosis,limited clinical therapy and high mortality together indicate that the development of effective therapeutics for IPF is an urgent need.In recent years,it was reported that DDRs are potential targets in anti-fibrosis treatment.Based on previous work we carried out further structure modifications and led to a more selective inhibitor 47 by averting some fibrosis-unrelated kinases,such as RET,AXL and ALK.Extensive profiling of compound 47 has demonstrated that it has potent DDR1/2 inhibitory activities,low toxicity,good pharmacokinetic properties and reliable in vivo anti-fibrosis efficacy.Therefore,we confirmed that discoidin domain receptors are promising drug targets for IPF,and compound 47 would be a promising candidate for further drug development.

Effects of bump parameters on hypersonic inlet starting performance

Unstart is an unwanted flow phenomenon in a hypersonic inlet. When an unstart occurs, the captured airflow flowing through the engine significantly decreases with strong unsteady characteristics, which may lead to thrust loss or even combustor flameout. In this study, various bump configurations were designed to be integrated with a hypersonic inlet to improve its starting ability. A bump was defined as an integrated 3D compression surface installed upstream of the inlet entrance. The starting processes of these bump inlets were numerically simulated to investigate the effect laws and flow mechanisms of the bump parameters. Tests on bump height revealed that the starting performance could be significantly improved by increasing bump height, with the starting Mach number decreasing by 0.55 for the inlet with the highest bump. The high bump facilitates the side movement of the subsonic flow in the separation zone, which leads to a small separation bubble, thus accelerating the starting process. Further, the starting ability can be improved by designing a relatively wide bump, which results in a decline in the starting Mach number by 0.44. When the bump has the same or greater width compared with the airflow capture range, a growing spillage along the transverse direction can be formed so that the airflow in the separation bubble can be easily excluded, improving the starting ability.