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.

Synaptic aging disrupts synaptic morphology and function in cerebellar Purkinje cells

Synapses are key structures in neural networks,and are involved in learning and memory in the central nervous system.Investigating synaptogenesis and synaptic aging is important in understanding neural development and neural degeneration in diseases such as Alzheimer disease and Parkinson’s disease.Our previous study found that synaptogenesis and synaptic maturation were harmonized with brain development and maturation.However,synaptic damage and loss in the aging cerebellum are not well understood.This study was designed to investigate the occurrence of synaptic aging in the cerebellum by observing the ultrastructural changes of dendritic spines and synapses in cerebellar Purkinje cells of aging mice.Immunocytochemistry,Di I diolistic assays,and transmission electron microscopy were used to visualize the morphological characteristics of synaptic buttons,dendritic spines and synapses of Purkinje cells in mice at various ages.With synaptic aging in the cerebellum,dendritic spines and synaptic buttons were lost,and the synaptic ultrastructure was altered,including a reduction in the number of synaptic vesicles and mitochondria in presynaptic termini and smaller thin specialized zones in pre-and post-synaptic membranes.These findings confirm that synaptic morphology and function is disrupted in aging synapses,which may be an important pathological cause of neurodegenerative diseases.

Stress injuries and autophagy in mouse hippocampus after chronic cold exposure

Cold exposure is an external stress factor that causes skin frostbite as well as a variety of diseases.Estrogen might participate in neuroprotection after cold exposure,but its precise mechanism remains unclear.In this study,mice were exposed to 10°C for 7 days and 0–4°C for 30 days to induce a model of chronic cold exposure.Results showed that oxidative stress-related c-fos and cyclooxygenase 2 expressions,MAP1LC3-labeled autophagic cells,Iba1-labeled activated microglia,and interleukin-1β-positive pyramidal cells were increased in the hippocampal CA1 area.Chronic cold exposure markedly elevated the levels of estrogen in the blood and the estrogen receptor,G protein-coupled receptor 30.These results indicate that neuroimmunoreactivity is involved in chronic cold exposure-induced pathological alterations,including oxidative stress,neuronal autophagy,and neuroimmunoreactivity.Moreover,estrogen exerts a neuroprotective effect on cold exposure.

人参皂甙Rg3对人喉鳞癌Hep-2细胞分泌性VEGF的影响(英文)

Objective: The aim of this study was to investigate the affecting of Rg3 to secreted VEGF of human laryngeal carcinoma Hep-2 cells and its mechanism of inhibition to tumor angiogenesis. Methods: Cultured human laryngeal cancer cell line Hep-2 and human vascular endothelial cells in vitro, cells got into the period of exponential phase of growth, was diviced into 3 groups: group I(control group), group II(DDP group), group III(Rg3 group). Added to the Hep-2 cells Rg3 and DDP, made Rg3 final concentration was 300 μg/mL, and DDP was 3 μg/mL. 48 h later, specimens from sample to be done immunocytochemistry, and the protein of VEGF in Hep-2 cells to be detected. Collecting Hep-2 cells supernatant, some was used to measure the protein level of VEGF in Hep-2 cells supernatant by ELISA. Some was used to culture HVEC. 24 h later,cell growth inhibition rate of human vascular endothelial was determined by MTT. Results: The protein level of VEGF was evidently higher in group I compared to group II and group III, it was not only in Hep-2 cells, but also in supernatant of Hep-2 cells.There was no significantly different between group II and group III. MTT results showed that, the human vascular endothelial cell growth inhibition rate of group I was significantly lower than that of group II and group III(P < 0.05). At the same time the HVEC growth inhibition rate of group II was significantly lower than that of group III(P < 0.05). Conclusion: The inhibition to tumor angiogenesis of Rg3 is stronger than traditional chemotherapy drug cisplatin. It worke by reducing the biological effects of secreted VEGF, But the effecting worke by reducing the activity of secreted VEGF itself or affecting endothelial function of VEGF receptor or some other ways to be further studied.

A Future Perspective on In-Sensor Computing

The use of artificial intelligence(AI)is escalating rapidly in most applications nowadays,thanks to breakthroughs in biology and mathematics.Novel hardware systems are greatly needed to meet the requirements of AI,which include computing capacity and energy efficiency.One of the major aims of AI is to mimic the functions of the human brain,which are enabled by the massive interconnection of neurons.For example,the visual cortex is the region of the brain that processes visual information.The human vision system,which includes the visual cortex,is highly compact and energy efficient.The retina contains hundreds of millions of light-sensitive neurons interconnected by preprocessing and control neurons to enhance image quality,extract features,and recognize objects.Once light-sensitive neurons have detected trivial signals,they are disabled thereafter,and only the critical information is transferred to the cortex for deep processing.

Effect of a Trace of Bi and Ni on the Microstructure and Wetting Properties of Sn-Zn-Cu Lead-Free Solder

The microstructure and melting behavior of Sn-9Zn-2Cu （SZC） lead-free solder with 3 wt pct Bi and various amount of Ni additions were studied. The wetting properties and the interracial reaction of Sn-Zn-Cu with Cu substrate were also examined. The results indicated that the addition of 3 wt pct Bi could decrease the melting point of the solder and Ni would refine the microstructure and the rod-shape Cu5Zn8 phase changed into square-shape （Cu, Ni）5Zn8 phase. The addition of Bi, Ni greatly improved the wettability of SZC solder. In addition, the interracial phase of the solders/Cu joint was typical planar Cu5Zn8 in SZC-3Bi-INi alloy.

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.

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.

BGB-A445,a novel non-ligand-blocking agonistic anti-OX40 antibody,exhibits superior immune activation and antitumor effects in preclinical models

t OX40 is a costimulatory receptor that is expressed primarily on activated CD4+,CD8+,and regulatory T cells.The ligation of OX40 to its sole ligand OX40L potentiates T cell expansion,differentiation,and activation and also promotes dendritic cells to mature to enhance their cytokine production.Therefore,the use of agonistic anti-Ox40 antibodies for cancer immunotherapy has gained great interest.However,most of the agonistic anti-OX40 antibodies in the clinic are OX40L-competitive and show limited efficacy.Here,we discovered that BGB-A445,a non-ligand-competitive agonistic anti-OX40 antibody currently under clinical investigation,induced optimal T cell activation without impairing dendritic cell function.In addition,BGB-A445 dose-dependently and significantly depleted regulatory T cells in vitro and in vivo via antibody-dependent cellular cytotoxicity.In the MC38 syngeneic model established in humanized OX40 knock-in mice,BGB-A445 demonstrated robust and dose-dependent antitumor efficacy,whereas the ligand-competitive anti-Ox40 antibody showed antitumor efficacy characterized by a hook effect.Furthermore,BGB-A445 demonstrated a strong combination antitumor effect with an anti-PD-1 antibody.Taken together,our findings show that BGB-A445,which does not block OX40-OX40L interaction in contrast to clinical-stage anti-OX40 antibodies,shows superior immune-stimulating effects and antitumor efficacy and thus warrants further clinical investigation.

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.

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.

1.3 GHz E-O bandwidth GaN-based micro-LED for multi-gigabit visible light communication

The data rate of a visible light communication(VLC) system is basically determined by the electrical-to-optical(E-O) bandwidth of its light-emitting diode(LED) source. In order to break through the intrinsic limitation of the carrier recombination rate on E-O bandwidth in conventional c-plane LEDs based on In Ga N quantum wells,a blue micro-LED with an active region of nano-structured In Ga N wetting layer is designed, fabricated, and packaged to realize a high-speed VLC system. The E-O bandwidth of the micro-LED can reach up to 1.3 GHz. Based on this high-speed micro-LED, we demonstrated a data rate of 2 Gbps with a bit error rate(BER) of 1.2×10^(-3) with simple on-off keying signal for a 3-m real-time VLC. In addition, a 4-Gbps VLC system using quadrature phase shift keying-orthogonal frequency-division multiplexing with a BER of 3.2×10^(-3) is also achieved for the same scenario. Among all the point-to-point VLC systems based on a single-pixel LED,this work has the highest distance-bandwidth product of 3 GHz·m and the highest distance-rate product of 12 Gbps·m.

Effect of solution treatment on microstructures and mechanical properties of AISI 321 service

A detailed knowledge of changes in microstructures and mechanical properties that occur in AISI 321 stainless steels service before and after solution treatment is of great interest, since the ductility and toughness of AISI 321 stainless steels may change drastically after service for a long time. After solution treatment at 1050 ℃, the microstructures of AISI 321 stMnless steels service for 80 000 h at 700 ℃ indicate that the content of sigma phase significantly decreased, the grains of austenite grew and the amount of twins together with the size increased with solution treatment time. The results of mechanical properties tests show that the impact toughness at room temperature was superior at solution treatment, and there was no obvious change in the impact toughness between different times of solution treatment at room temperature.

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.

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.

Ultrafast and low-power optoelectronic infrared-to-visible upconversion devices

Photon upconversion with transformation of low-energy photons to high-energy photons has been widely studied and especially applied in biomedicine for sensing, stimulation, and imaging. Conventional upconversion materials rely on nonlinear luminescence processes, suffering from long decay lifetime or high excitation power. Here,we present a microscale, optoelectronic infrared-to-visible upconversion device design that can be excited at low power(1–100 mW∕cm^2). By manipulating device geometry, illumination position, and temperature, the device luminescence decay lifetime can be tuned from tens to hundreds of nanoseconds. Based on carrier transportation and circuit dynamics, theoretical models are established to understand the transient behaviors. Compared with other mechanisms, the optoelectronic upconversion approach demonstrates the shortest luminescence lifetime with the lowest required excitation power, owing to its unique photon–electron conversion process. These features are expected to empower the device with essential capabilities for versatile applications as high-performance light emitters.

Size-dependent optical properties of InGaN quantum dots in GaN nanowires grown by MBE

Quantum dots in nanowires （DINWs） are considered as important building blocks for novel nanoscale semiconductor optoelectronic devices. In this paper, pure axial heterojunction InGaN/GaN DINWs are grown by using plasma-assisted molecular beam epitaxy （PA-MBE） system. The InGaN quantum dots （QDs） are disk-like observed by scanning electron microscopy （SEM） and transmission electron microscopy （TEM）. The diameter of QDs can be controlled by the growth conditions of nanowires （NWs）, while the thickness of QDs can be controlled by the growth time of lnGaN. Temperature-dependent photoluminescence （TDPL） measurements demonstrate that the PL peak of DINWs with small and uniform sizes shows a general red shift with increasing temperature. However, the PL peak of D1NWs with non-uniform sizes shows an abnormal blue shift with increasing temperature, which is due to different internal quantum efficiencies of the DINWs with different sizes.

Distributed parameter circuit model for wideband photodiodes with inductive coplanar waveguide electrodes

An equivalent circuit model including multi-section distributed parameters is proposed to analyze wideband photodiodes(PDs)with coplanar waveguide(CPW)electrodes.The model helps extract CPW parameters as well as intrinsic bandwidth parameters so that the influence of theCPW structure can be investigated,making it valuable for the design of high-performance PDs.PDs with an inductive 115Ωimpedance CPW are fabricated,and the 3 dB bandwidth is improved from 28 GHz to 37.5 GHz compared with PDs with a conventional 50Ωimpedance CPW.

Simple dynamic energy core equivalent rays method to design freeform surface for extended source

A simple method is proposed to design free- form surface for Lambertian extended source. In this method, it can take advantage of the designing method for point source via substituting each incident ray with a dynamically calculated equivalent ray. For each facet on the freeform surface, the equivalent ray emits from the energy weighted average-emitting-position for the corre- sponding incident beam, and redirects into the direction which is determined by a source-to-target mapping. The results of the designing examples show that the light distributions＇ uniformities can be improved by this method, e.g., even the improvement of 59% can be achieved.