EEG光子处理器——基于衍射光子计算单元的癫痫发作检测

Electroencephalography(EEG)analysis extracts critical information from brain signals,enabling brain disease diagnosis and providing fundamental support for brain–computer interfaces.However,performing an artificial intelligence analysis of EEG signals with high energy efficiency poses significant challenges for electronic processors on edge computing devices,especially with large neural network models.Herein,we propose an EEG opto-processor based on diffractive photonic computing units(DPUs)to process extracranial and intracranial EEG signals effectively and to detect epileptic seizures.The signals of the EEG channels within a second-time window are optically encoded as inputs to the constructed diffractive neural networks for classification,which monitors the brain state to identify symptoms of an epileptic seizure.We developed both free-space and integrated DPUs as edge computing systems and demonstrated their applications for real-time epileptic seizure detection using benchmark datasets,that is,the Children’s Hospital Boston(CHB)–Massachusetts Institute of Technology(MIT)extracranial and Epilepsy-iEEG-Multicenter intracranial EEG datasets,with excellent computing performance results.Along with the channel selection mechanism,both numerical evaluations and experimental results validated the sufficiently high classification accuracies of the proposed opto-processors for supervising clinical diagnosis.Our study opens a new research direction for utilizing photonic computing techniques to process large-scale EEG signals and promote broader applications.

解析光电化学氮还原合成氨中局域电子结构和合金化的协同效应

氨是氮肥等工业的主要原料,因此氨产量居各种化工产品的首位.目前,90%以上的氨通过传统Haber-Bosch法制得,但该反应需要在高温高压下进行,消耗大量能源,同时排放大量CO_(2).基于此,科研人员致力于寻求一种绿色、高效的合成氨替代方法.其中,利用太阳能,通过光电化学氮还原合成氨是最有潜力和竞争力的方法之一,该方法也为有效利用太阳能提供了新途径.目前,虽然光电化学氮还原研究取得了一定进展,但是氨产率和氮转换效率低限制了其经济可行性.这主要归因于四个方面:(1)牢固的氮氮三键使得氮气难以活化;(2)复杂的多步和多电子反应使得动力学迟缓;(3)析氢竞争反应降低了太阳能-氨的转换效率;(4)氮气在水溶液中的溶解度低导致吸附在光电阴极表面的氮气较少.为解决上述问题,本文通过溅射法在B掺杂的p型(100)晶向硅片上共沉积Au,Co和Pd,然后在600℃下和空气中快速退火,制得由助催化剂/保护层/光吸收层组成的层级硅基光电阴极,并用于氮还原合成氨.成分和结构表征结果表明,层级硅基光电阴极由p型硅光吸收层、二氧化硅保护薄层和AuCoPd合金纳米颗粒助催化剂组成,该电极可表示为AuCoPd-CoOx/SiO_(2)/Si,简称ACP电阴极.角分辨X射线光电子能谱和同步辐射X射线吸收光谱结果表明,形成了局域电子结构AuCoPd合金纳米颗粒,并可分析出Au离子和Pd离子在纳米颗粒上的比例和分布.变压光电化学实验结果表明,ACP光电阴极表现出较好的氮还原合成氨性能,在3 MPa下氨产率达到22.2±0.4μg·h^(-1)·cm^(-2),法拉第效率达到22.9%.同时,ACP光电阴极的光电化学氮还原行为遵循勒夏特列(化学平衡移动)原理:随着反应压强增加,氨产率、法拉第效率和起始光电压均随之增大.原位X射线光电子能谱和原位同步辐射X射线吸收光谱结果表明,Au离子和Pd离子为氮还原反应的活性位点,为氮气活化及加氢提供反应场所;同时,揭示了邻近的Pd元素为Au物种上活化的氮气提供了活性质子,促进了氮还原合成氨反应进程.综上,本文为设计高效且稳定的光电阴极并应用于光电化学氮还原反应提供一定的参考.

Hollow Gradient-Structured Iron-Anchored Carbon Nanospheres for Enhanced Electromagnetic Wave Absorption

In the present paper,a microwave absorber with nanoscale gradient structure was proposed for enhancing the electromagnetic absorption performance.The inorganic-organic competitive coating strategy was employed,which can effectively adjust the thermodynamic and kinetic reactions of iron ions during the solvothermal process.As a result,Fe nanoparticles can be gradually decreased from the inner side to the surface across the hollow carbon shell.The results reveal that it offers an outstanding reflection loss value in combination with broadband wave absorption and flexible adjustment ability,which is superior to other relative graded distribution structures and satisfied with the requirements of lightweight equipment.In addition,this work elucidates the intrinsic microwave regulation mechanism of the multiscale hybrid electromagnetic wave absorber.The excellent impedance matching and moderate dielectric parameters are exhibited to be the dominative factors for the promotion of microwave absorption performance of the optimized materials.This strategy to prepare gradient-distributed microwave absorbing materials initiates a new way for designing and fabricating wave absorber with excellent impedance matching property in practical applications.

Integrated strategies for chemotherapy cycles in nasopharyngeal carcinoma patients: Real-world data from two epidemic centers guiding decision-making

objective:Two cycles of induction chemotherapy(IC)followed by 2 cycles of platinum-based concurrent chemoradiotherapy(CCRT)(2IC+2CCRT)for locoregionally advanced nasopharyngeal carcinoma(LA-NPC)is widely adopted but not evidence-confirmed.This study aimed to determine the clinical value of 2IC+2CCRT regarding efficacy,toxicity and cost-effectiveness.Methods:This real-world study from two epidemic centers used propensity score matching(PSM)and inverse probability of treatment weighting(IPTW)analyses.The enrolled patients were divided into three groups based on treatment modality:Group A(2IC+2CCRT),Group B(3IC+2CCRT or 2IC+3CCRT)and Group C(3IC+3CCRT).Long-term survival,acute toxicities and cost-effectiveness were compared among the groups.We developed a prognostic model dividing the population into high-and low-risk cohorts,and survivals including overall survival(OS),progression-free survival(PFS),distant metastasis-free survival(DMFS)and locoregional relapse-free survival(LRRFS)were compared among the three groups according to certain risk stratifications.Results:Of 4,042 patients,1,175 were enrolled,with 660,419,and 96 included in Groups A,B and C,respectively.Five-year survivals were similar among the three groups after PSM and confirmed by IPTW.Grade 3-4 neutropenia and leukocytopenia were significantly higher in Groups C and B than in Group A(52.1%vs.41.5%vs.25.2%;41.7%vs.32.7%vs.25.0%)as were grade 3-4 nausea/vomiting and oral mucositis(29.2%vs.15.0%vs.6.1%;32.3%vs.25.3%vs.18.0%).Cost-effective analysis suggested that 2IC+2CCRT was the least expensive,while the health benefits were similar to those of the other groups.Further exploration showed that 2IC+2CCRT tended to be associated with a shorter PFS in high-risk patients,while 3IC+3CCRT potentially contributed to poor PFS in low-risk individuals,mainly reflected by LRRFS.Conclusions:In LA-NPC patients,2IC+2CCRT was the optimal choice regarding efficacy,toxicity and costeffectiveness;however,2IC+2CCRT and 3IC+3CCRT probably shortened LRRFS in high-and low-risk populations,respectively.

Comparison between different reconstruction routes in esophageal squamous cell carcinoma

AIM:To compare postoperative complications and prognosis of esophageal squamous cell carcinoma patients treated with different routes of reconstruction. METHODS:After obtaining approval from the Medical Ethics Committee of the Sun Yat-Sen University Cancer Center, we retrospectively reviewed data from 306 consecutive patients with histologically diagnosed esophageal squamous cell carcinoma who were treated between 2001 and 2011. All patients underwent radical McKeown-type esophagectomy with at least two-field lymphadenectomy. Regular follow-up was performed in our outpatient department. Postoperative complica-tions and long-term survival were analyzed by treatment modality, baseline patient characteristics, and operative procedure. Data from patients treated via the retrosternal and posterior mediastinal routes were compared. RESULTS:The posterior mediastinal and retrosternal reconstruction routes were employed in 120 and 186 patients, respectively. Pulmonary complications were the most common complications experienced during the postoperative period (46.1% of all patients; 141/306). Compared to the retrosternal route, the posterior mediastinal reconstruction route was associated with a lower incidence of anastomotic stricture (15.8% vs 27.4%, P = 0.018) and less surgical bleeding (242.8 ± 114.2 mL vs 308.2 ± 168.4 mL, P < 0.001). The median survival time was 26.8 mo (range:1.6-116.1 mo). Upon uni/multivariate analysis, a lower preoperative albumin level (P = 0.009) and a more advanced pathological stage (pT; P = 0.006; pN; P < 0.001) were identified as independent factors predicting poor prognosis. The reconstruction route did not influence prognosis (P = 0.477). CONCLUSION:The posterior mediastinal route of reconstruction reduces incidence of postoperative complications but does not affect survival. This route is recommended for resectable esophageal squamous cell carcinoma.

Managing esophageal fistulae by endoscopic transluminal drainage in esophageal cancer patients with superior mediastinal sepsis after esophagectomy

The management of postoperative leaks into the mediastinum after esophagectomy remains a challenge. We describe our clinical management of this complication through endoscopic transluminal drainage. Between 2008 and 2011, 4 patients with esophageal squamous cell carcinoma (ESCC) who underwent McKeown-type esophagectomy with two-field lymphadenectomy experienced complicated anastomotic fistulae in the presence of superior mediastinal sepsis. All 4 patients underwent endoscopic transluminal drainage, and all survived. The mean healing period was 50 days (range, 31 to 58 days), the mean stay in the intensive care unit was 7.3 days (range, 1 to 18 days), and the mean hospital stay was 64.5 days (range, 49 to 70 days). Endoscopically guided transluminal drainage should be considered for ESCC patients with superior mediastinal fistulae after esophagectomy.

Prognostic value of preoperative mean corpuscular volume in esophageal squamous cell carcinoma

AIM: To evaluate whether preoperative mean corpuscular volume (MCV) is a prognostic indicator in patients with resectable esophageal squamous cell carcinoma (ESCC). METHODS: A total of 298 consecutive, prospectively enrolled patients with histologically diagnosed ESCC who underwent surgery with curative intent from 2001 to 2011 were retrospectively evaluated. Patients were excluded if they had previous malignant disease, distant metastasis at the time of primary treatment, a history of neoadjuvant treatment, had undergone nonradical resection, or had died of a non-tumor-associated cause. Survival status was verified in September 2011. Pathological staging was performed based on the 2010 American Joint Committee on Cancer criteria. Preoperative MCV was obtained from blood counts performed routinely within 7 d prior to surgery. Receiver operating characteristic (ROC) curve analysis was used to determine a cutoff for preoperative MCV. RESULTS: The 298 patients consisted of 230 males and 68 females, with a median follow-up of 30.1 mo. ROC analysis showed an optimal cutoff for preoperative MCV of 95.6 fl. Fifty-nine patients (19.8%) had high (> 95.6 fl) and 239 (80.2%) had low (≤ 95.6 fl) preoperative MCV. Preoperative MCV was significantly associated with gender (P=0.003), body mass index (P=0.017), and preoperative red blood cell count (P<0.001). The predicted 1-, 3and 5-year overall survival (OS) rates were 72%, 60% and 52%, respectively. Median OS was significantly longer in patients with low than with high preoperative MCV (27.5 mo vs 19.4 mo, P<0.001). Multivariate analysis showed that advanced pT (P=0.018) and pN (P<0.001) stages, upper thoracic location (P=0.010), lower preoperative albumin concentration (P=0.002), and high preoperative MCV (P=0.001) were negative prognostic factors in patients with ESCC. Preoperative MCV also stratified OS in patients with T3, N1-N3, G2-G3 and stage Ⅲ tumors. CONCLUSION: Preoperative MCV is a prognostic factor in patients with ESCC.

Electrically Tunable Wafer-Sized Three-Dimensional Topological Insulator Thin Films Grown by Magnetron Sputtering

Three-dimensional(3 D)topological insulators(TIs)are candidate materials for various electronic and spintronic devices due to their strong spin-orbit coupling and unique surface electronic structure.Rapid,low-cost preparation of large-area TI thin films compatible with conventional semiconductor technology is the key to the practical applications of TIs.Here we show that wafer-sized Bi2Te3 family TI and magnetic TI films with decent quality and well-controlled composition and properties can be prepared on amorphous SiO2/Si substrates by magnetron cosputtering.The SiO2/Si substrates enable us to electrically tune(Bi1-xSbx)2Te3 and Cr-doped(Bi1-xSbx)2 Te3 TI films between p-type and n-type behavior and thus study the phenomena associated with topological surface states,such as the quantum anomalous Hall effect(QAHE).This work significantly facilitates the fabrication of TI-based devices for electronic and spintronic applications.

Interactive free-viewpoint video generation

Background Free-viewpoint video(FVV)is processed video content in which viewers can freely select the viewing position and angle.FVV delivers an improved visual experience and can also help synthesize special effects and virtual reality content.In this paper,a complete FVV system is proposed to interactively control the viewpoints of video relay programs through multimedia terminals such as computers and tablets.Methods The hardware of the FVV generation system is a set of synchronously controlled cameras,and the software generates videos in novel viewpoints from the captured video using view interpolation.The interactive interface is designed to visualize the generated video in novel viewpoints and enable the viewpoint to be changed interactively.Results Experiments show that our system can synthesize plausible videos in intermediate viewpoints with a view range of up to 180°.

Localizing and Characterizing Colloidal Particles Scattering Using Lens-free Holographic Microscopy

Lens-free holographic microscopy could achieve both improved resolution and field of view(FOV), which has huge potential applications in biomedicine, fluid mechanics and soft matter physics. Unfortunately, due to the limited sensor pixel size, target objects could not be located to a satisfactory level. Recent studies have shown that electromagnetic scattering can be fitted to digital holograms to obtain the 3 D positions of isolated colloidal spheres with nanometer precision and millisecond temporal resolution. Here, we describe a lens-free holographic imaging technique that fits multi-sphere superposition scattering to digital holograms to obtain in situ particle position and model parameters: size and refractive index of colloidal spheres. We show that the proposed method can be utilized to analyze the location and character of colloidal particles under large FOV with high density.

The synergistic catalysis on Co nanoparticles and CoNx sites of aniline-modified ZIF derived Co@NCs for oxidative esterification of HMF

An efficient sustainable and scalable strategy for the synthesis of porous cobalt/nitrogen co-doped carbons(Co@NCs) via pyrolysis of aniline-modified ZIFs,has been demonstrated.Aniline can coordinate and absorb on the surface of ZIF(ZIF-CoZn3-PhA),accelerate the precipitation of ZIFs,thus resulting in smaller ZIF particle size.Meanwhile,the aniline on the surface of ZIF-CoZn3-PhA promotes the formation of the protective carbon shell and smaller Co nanoparticles,and increases nitrogen content of the catalyst.Because of these prope rties of Co@NC-PhA-3,the oxidative esterification of 5-hydroxymethylfurfural can be carried out under ambient conditions.According to our experimental and computational results,a synergistic catalytic effect between CoNx sites and Co nanoparticles has been established,in which both Co nanoparticles and CoNx can activate O2 while Co nanoparticles bind and oxidize HMF.Moreover,the formation and release of active oxygen species in CoNx sites are reinfo rced by the electronic interaction between Co nanoparticles and CoNx.

Review on thermochromic vanadium dioxide based smart coatings： from lab to commercial application

With an urgent demand of energy efficientcoatings for building fenestrations, vanadium dioxide（VO2）-based thermochromic smart coatings have beenwidely investigated due to the reversible phase transition ofVO2 at a critical transition temperature of 68 ℃, which isaccompanied by the modulation of solar irradiation, espe-cially in the near-infrared region. As for commercialapplications in our daily life, there are still some obstaclesfor VO2-based smart coatings, such as the high phasetransition temperature, optical properties （luminous trans-mittance and solar modulation ability）, environmental sta-bility in a long-time period, as well as mass production. Inthis review, recent progress of thermochromic smart coat-ings to solve above obstacles has been surveyed. Mean-while, future development trends have also been given topromote the goal of commercial production of VO2 smartcoatings.

Dual-color terahertz spatial light modulator for single-pixel imaging

Spatial light modulators(SLM),capable of dynamically and spatially manipulating electromagnetic waves,have reshaped modern life in projection display and remote sensing.The progress of SLM will expedite next-generation communication and biomedical imaging in the terahertz(THz)range.However,most current THz SLMs are adapted from optical alternatives that still need improvement in terms of uniformity,speed,and bandwidth.Here,we designed,fabricated,and characterized an 8×8THz SLM based on tunable liquid crystal metamaterial absorbers for THz single-pixel compressive imaging.We demonstrated dual-color compressive sensing(CS)imaging for dispersive objects utilizing the large frequency shift controlled by an external electric field.We developed auto-calibrated compressive sensing(ACS)algorithm to mitigate the impact of the spatially nonuniform THz incident beam and pixel modulation,which significantly improves the fidelity of reconstructed images.Furthermore,the complementary modulation at two absorption frequencies enables Hadamard masks with negative element values to be realized by frequency-switching,thereby halving the imaging time.The demonstrated imaging system paves a new route for THz single-pixel multispectral imaging with high reliability and low cost.

The role of prior in image based 3D modeling： a survey

The prior knowledge is the significant supple- ment to image-based 3D modeling algorithms for refining the fragile consistency-based stereo. In this paper, we review the image-based 3D modeling problem according to prior cate- gories, i.e., classical priors and specific priors. The classical priors including smoothness, silhouette and illumination are well studied for improving the accuracy and robustness of the 3D reconstruction. In recent years, various specific priors which take advantage of Manhattan rule, geometry template and trained category features have been proposed to enhance the modeling performance. The advantages and limitations of both kinds of priors are discussed and evaluated in the paper. Finally, we discuss the trend and challenges of the prior studies in the future.

光致变色材料YHxOy中超快过程的激发态密度泛函理论研究

含氧稀土金属氢化物YH_xO_y是一种新发现的、具有快速光响应的光致变色材料.尽管其制备方法、光学性质和结构特征已被广泛研究,但YH_xO_y中的光致变色机理仍然未知.本文采用基于最新开发的含时密度泛函理论的激发态分子动力学模拟研究了YH_xO_y中的光化学反应.结果发现,光激发下在100 fs内可以形成一种双氢缺陷.该双氢缺陷为浅施主,使材料表现出强n型掺杂行为,这可能是导致YH_xO_y中光致变色效应的原因.此外还发现,氧浓度会影响双氢缺陷的稳定性,这意味着双氢解离的能垒与氧浓度有关.在此模型中,当O/Y=1:8时,双氢解离的能垒约为0.28 eV.若氧浓度过低,在关闭激发时双氢会迅速解离;若氧浓度过高,即使在光激发下双氢也会快速解离.

Light-field micro-endoscopy using a fiber bundle:a snapshot 3D epi-fluorescence endoscope

Micro-endoscopes are widely used for detecting and visualizing hard-to-reach areas of the human body and for in vivo observation of animals.A micro-endoscope that can realize 3D imaging at the camera framerate could benefit various clinical and biological applications.In this work,we report the development of a compact light-field micro-endoscope(LFME)that can obtain snapshot 3D fluorescence imaging,by jointly using a single-mode fiber bundle and a small-size light-field configuration.To demonstrate the real imaging performance of our method,we put a resolution chart in different z positions and capture the z-stack images successively for reconstruction,achieving 333-μm-diameter field of view,24μm optimal depth of field,and up to 3.91μm spatial resolution near the focal plane.We also test our method on a human skin tissue section and He La cells.Our LFME prototype provides epi-fluorescence imaging ability with a relatively small(2-mm-diameter)imaging probe,making it suitable for in vivo detection of brain activity and gastrointestinal diseases of animals.

Flexible Au micro-array electrode with atomic-scale Au thin film for enhanced ethanol oxidation reaction

The catalysis of Au thin film could be improved by fabrication of array structures in large area.In this work,nanoimprint lithography has been developed tofabricate flexible Au micro-array(MA)electrodes with~100%coverage.Advanced electron microscopy characterisations have directly visualised the atomic-scale three-dimensional(3D)nanostructures with a maximum depth of 6 atomic layers.In-situ observation unveils the crystal growth in the form of twinning.High double layer capacitance brings about large number of active sites on the Au thin film and has a logarithmic relationship with mesh grade.Electrochemistry testing shows that the Au MAs perform much better ethanol oxidation reaction than the planar sample;MAs with higher mesh grade have a greater active site utilisation ratio(ASUR),which is important to build electrochemical double layer for efficient charge transfer.Further improvement on ASUR is expected for greater electrocatalytic performance and potential application in direct ethanol fuel cell.

Optical switching properties of Pd-Ni thin-film top-capped switchable mirrors

Switchable mirrors based on magnesium-nickel alloy thin films capped with catalytic Pd-Ni alloy thin films were prepared by a DC magnetron sputtering method. Their composition, structure and surface morphology were studied by XPS, XRD and AFM. Herein, the optical switching properties and durability of the switchable mirrors were investigated by varying the Ni content in the Pd-Ni alloys. Comparing pure Pd catalyst with Pd-Ni top-capped switchable mirrors, the latter show better hydrogenation and dehydrogenation kinetics, and the speed of hydrogen desorption is obviously improved with increasing Ni content in the Pd-Ni alloy. The Pd-Ni capped switchable mirrors also have better optical switching durability. The catalytic Pd layer with the addition of Ni does not influence the transmittance （hydride state） and reflectance （metallic state） of the switchable mirrors. In addition, replacing Pd with Pd-Ni alloy decreases the cost of the switchable mirrors： employing nickel in the alloy Pd89.2Ni10.8 can save about 11% use of Pd. Therefore, the Pd-Ni alloy can provide a cheaper catalytic thin film, and it is expected to have applications in energy-saving windows, hydrogen sensors and hydrogen storage materials.

High-resolution spectral video acquisition

与传统视频采集技术相比,高分辨率光谱视频采集技术能够为精细农业、环境监测、遥感、军事刑侦等诸多重要领域提供高维度、高精度场景特征信息。传统光谱仪主要采用的扫描系统无法满足动态场景下的采集需求,从而限制了光谱成像技术的应用范围。近来,得益于计算摄像理论和半导体技术的快速发展,光谱视频采集技术成为可能。本文首先详细介绍了传统光谱仪的基本理论与工作原理。其次,针对光谱视频采集的核心问题,从成像理论、系统结构、关键器件等方面回顾了近年出现的瞬拍式光谱采集技术。从进一步提升光谱视频采集精度的角度出发,通过主观质量评价与客观指标比较,分析和总结了各光谱成像系统的性能优势与弊端,同时讨论了计算摄像理论、半导体制备工艺对光谱视频采集技术发展的关键作用。

Correction to“Multifunctional Flexible Vanadium Dioxide Films”

The author affiliation of the author Ying Zhu should be changed to“State Key Laboratory of High-Performance Ceramics and Superfine Microstructure,Shanghai Institute of Ceramics,Chinese Academy of Sciences,Shanghai 200050,China”.Miss Zhu received her M.S.in Materials Engineering from Shanghai Institute of Ceramics,Chinese Academy of Sciences,in 2020.Then she became a joint Ph.D.student of The University of British Columbia,Canada and Southern University of Science and Technology,China.