Dark count rate and band to band tunneling optimization for single photon avalanche diode topologies

This paper proposes two optimal designs of single photon avalanche diodes(SPADs) minimizing dark count rate(DCR). The first structure is introduced as p^+/pwell/nwell, in which a specific shallow pwell layer is added between p^+and nwell layers to decrease the electric field below a certain threshold. The simulation results show on average 19.7%and 8.5% reduction of p^+/nwell structure’s DCR comparing with similar previous structures in different operational excess bias and temperatures respectively. Moreover, a new structure is introduced as n+/nwell/pwell, in which a specific shallow nwell layer is added between n+and pwell layers to lower the electric field below a certain threshold. The simulation results show on average 29.2% and 5.5% decrement of p^+/nwell structure’s DCR comparing with similar previous structures in different operational excess bias and temperatures respectively. It is shown that in higher excess biases(about 6 volts), the n+/nwell/pwell structure is proper to be integrated as digital silicon photomultiplier(dSiPM) due to low DCR. On the other hand, the p^+/pwell/nwell structure is appropriate to be utilized in dSiPM in high temperatures(above 50?C) due to lower DCR value.

Effect of Source to Camera Distance and Count Rate on Intrinsic Uniformity of SPECT Gamma Camera

In this research, the excellent parameter for regular Quality Control (QC) testing of intrinsic uniformity for dual-head Single Photon Emission Computed Tomography (SPECT) gamma camera is determined. The integral and differential intrinsic uniformity tests for both Useful Field Of View (UFOV) and Centre Field Of View (CFOV) were done by insertion a point-source of 99mTc in front of the detectors with detached collimators to measure the effect of source to camera distance and a count rate on intrinsic uniformity. The result reveals that the best intrinsic uniformity image is obtained at source-to-camera distance of 3 m and a count rate between 16 and 60 M.

Fiber coupled high count-rate single-photon generated from InAs quantum dots

In this work,we achieve high count-rate single-photon output in single-mode(SM)optical fiber.Epitaxial and dilute InAs/GaAs quantum dots(QDs)are embedded in a GaAs/AlGaAs distributed Bragg reflector(DBR)with a micro-pillar cavity,so as to improve their light emission extraction in the vertical direction,thereby enhancing the optical SM fiber’s collection capabil-ity(numerical aperture:0.13).By tuning the temperature precisely to make the quantum dot exciton emission resonant to the micro-pillar cavity mode(Q~1800),we achieve a fiber-output single-photon count rate as high as 4.73×10^(6) counts per second,with the second-order auto-correlation g2(0)remaining at 0.08.

An active base designed in high-counting-rate applications for Hamamatsu R1924A photomultiplier tube

Hamamatsu R1924A is one of the most widely used photomultiplier tubes(PMTs) in nuclear physics.Since the active base suitable for R1924A is still not available in market, an active base is designed for Hamamatsu R1924A PMT, and the test results at high counting rates are presented. The active bases with two different sets of resistor chains were tested and compared by a frequency-controlled green straw hat LED light. A stable signal output up to 100 kHz is achieved using frequency-controlled LED pulsed light. The temperature of bases, which reflects the power consumption and is crucial for applications in vacuum, is also monitored with the same LED pulsed light. The temperature of the active base with smaller resistances reaches about twice of that of the active base with larger resistances in the resistor chain. For the applications in vacuum, the active base with resistance between the two sets of resistor chains may be preferable.

Evaluation of autonomic nervous system by heart rate variability and differential count of leukocytes in athletes

Top Japanese sprinters were evaluated for their physical condition, autonomic function, blood chemistry, differential leukocyte count and blood lactate level before and after short, maximal exercise to explore methods of quantifying their conditioning level. Statistical analysis of data obtained before and 10 min after exercise were used to estimate the athletes’ autonomic capacity during recovery. Pre and post exercise variances in differential leukocyte count revealed strong correlations between neutrophil and sympathetic activity, and lymphocyte and parasympathetic activity. The results of the study demonstrated significant alterations in autonomic parameters and differential white blood cell count in response to maximal exercise.

基于弹道亏损形状特征的堆积脉冲识别方法

识别与拒绝堆积脉冲是提升高辐射环境下X荧光光谱性能的有效方法。本文提出一种堆积脉冲甄别方法,该方法首先将原始脉冲成形为三角脉冲和梯形脉冲;然后计算其幅度比值,该比值称为时不变脉冲形状标签(TIPS);最后通过TIPS的大小判别脉冲是否堆积。这种方法不需要测量脉冲宽度,且不受脉冲幅度变化的影响。与逆锯齿波成形器相比,三角脉冲成形器能更有效地抑制TIPS展宽,从而有利于甄别堆积脉冲。在1.22×10^(6)s^(-1)通过率下,使用该方法识别铅黄铜样品中堆积脉冲。结果表明,当非堆积脉冲损失率为15%时,准确率、召回率及F1得分分别提升到73.55%、78.75%和76.06%,铜的Kα峰峰总比提高到76.60%。本文提出的方法可以有效识别堆积脉冲和提高能谱的峰总比。

An Interconnection between Elevated SCC Levels in Milk around the First Artificial Insemination and Pregnancy Rate in Dairy Cows

The aim of this study was to evaluate the impact of the somatic cell count (SCC) levels measured at 28-test-day intervals or pregnancy rate at the first artificial insemination of Holstein Friesian cows. All necessary information was taken from test day and farm records. Levels of SCC in milk, 30 days before, and 30 days after the first artificial insemination (FAI) date were divided into 4 categories and their interconnection with pregnancy rate (PR) at FAI was evaluated by applying logistic models. A SCC threshold of 150.000 cells/ml of milk was used to differentiate uninfected udders and infected udders of Holstein Friesian cows. A level of SCC > 150.000 cells/ml in milk, and a level of SCC < 150.000 cells/ml before and after FAI respectively were considered udders with new infections. A level of SCC > 150.000 cells/ml in milk before FAI as well as after FAI, was considered chronically infected udders or subclinical intramammary infections (IMI). Data from 792 FAIs from farm and test day records over a 4-year period (2019-2022) were evaluated. The outcome of this study revealed that the risk for low PR at the first AI was increased in cows with infected udders (OR = 1.33, CI 0.99 - 1.78), compared with uninfected udders. Increased levels of SCC after FAI had a negative effect on PR, while before FAI was not affected. To achieve a good PR, mastitis control measures must be fully adopted to a large extent around the first AI.

Research on the correlation between the dual diffusion behavior of zinc in InGaAs/InP single-photon avalanche photodiodes and device performance

The development of InGaAs/InP single-photon avalanche photodiodes(SPADs)necessitates the utiliza-tion of a two-element diffusion technique to achieve accurate manipulation of the multiplication width and the dis-tribution of its electric field.Regarding the issue of accurately predicting the depth of diffusion in InGaAs/InP SPAD,simulation analysis and device development were carried out,focusing on the dual diffusion behavior of zinc atoms.A formula of X_(j)=k√t-t_(0)+c to quantitatively predict the diffusion depth is obtained by fitting the simulated twice-diffusion depths based on a two-dimensional(2D)model.The 2D impurity morphologies and the one-dimensional impurity profiles for the dual-diffused region are characterized by using scanning electron micros-copy and secondary ion mass spectrometry as a function of the diffusion depth,respectively.InGaAs/InP SPAD devices with different dual-diffusion conditions are also fabricated,which show breakdown behaviors well consis-tent with the simulated results under the same junction geometries.The dark count rate(DCR)of the device de-creased as the multiplication width increased,as indicated by the results.DCRs of 2×10^(6),1×10^(5),4×10^(4),and 2×10^(4) were achieved at temperatures of 300 K,273 K,263 K,and 253 K,respectively,with a bias voltage of 3 V,when the multiplication width was 1.5µm.These results demonstrate an effective prediction route for accu-rately controlling the dual-diffused zinc junction geometry in InP-based planar device processing.

个体化口腔护理干预措施对舌癌术后患者的效果

目的分析个体化口腔护理干预措施对舌癌术后患者口腔清洁度、肌皮瓣成活率的影响。方法选取厦门大学附属第一医院2020年1月—2023年4月收治的104例舌癌患者,按其住院号单双数分为参照组(住院号单数患者52例)与研究组(住院号双数患者52例)。参照组实施常规护理,研究组在参照组常规护理基础上实施个体化口腔护理干预。比较2组患者护理前后口腔菌落计数,统计2组口腔清洁度、肌皮瓣成活率,并对比2组护理前后生活质量评分。结果护理后,2组口腔菌落计数低于护理前,且研究组口腔菌落计数为(24.71±6.34)×10^(4),低于参照组的(38.34±5.66)×10^(4)(P<0.05);研究组口腔清洁度优良率为96.15%,高于参照组的78.85%(P<0.05);研究组肌皮瓣成活率为98.08%,高于参照组的84.62%(P<0.05);护理后,研究组生活质量评分为(74.56±6.12)分,高于参照组的(69.72±6.07)分(P<0.05)。结论实施个体化口腔护理可有效减少患者术后口腔菌落,提高其口腔清洁度,确保肌皮瓣成功存活,进而改善患者生活质量。

NEUT、ESR、Gal-3水平与感染性心内膜炎患者临床预后的关系

目的探讨中性粒细胞计数(neutrophil count,NEUT)、红细胞沉降率(erythrocyte sedimentation rate,ESR)、半乳糖凝集素-3(galectin-3,Gal-3)水平与感染性心内膜炎(infective endocarditis,IE)患者临床预后的关系。方法选取2021年2月至2023年4月商洛市中心医院收治的88例IE患者,其中男49例,女39例,平均年龄46.20岁,心功能分级Ⅱ~Ⅲ级54例、Ⅳ级34例。随访1年,根据预后结果,将患者分为预后良好组(54例)和预后不良组(34例)。单因素分析患者的临床资料和实验室指标等,然后通过多因素logistic回归分析IE患者预后不良的危险因素。受试者操作特征曲线(ROC)评估NEUT、ESR和Gal-3水平对IE患者预后不良的预测能力。采用t检验、χ^(2)检验。结果预后不良组与预后良好组心功能分级、Pitt评分、治疗前NEUT水平、治疗2周后NEUT、ESR和Gal-3水平比较,差异均有统计学意义(均P<0.05)。多因素logistic回归分析结果显示,心功能分级为Ⅳ级、Pitt评分≥2分及治疗2周后高NEUT、ESR和Gal-3水平是IE患者预后不良的独立危险因素(均P<0.05)。治疗2周后NEUT、ESR和Gal-3水平及三者联合预测IE患者预后不良的曲线下面积(AUC)分别为0.912、0.949、0.905和0.985。结论NEUT、ESR、Gal-3水平在IE患者中具有重要的临床预测价值。高水平的NEUT、ESR和Gal-3与IE患者的不良预后密切相关,可以作为独立的不良预后风险因素,能够为临床提供更精准的风险评估和治疗决策支持。

室温下高探测效率InGaAsP/InP单光子雪崩二极管

描述了一种高性能平面InGaAsP/InP单光子雪崩二极管(SPAD),该二极管具有单独的吸收、分级、电荷和倍增(SAGCM)异质结构。通过电场调节和缺陷控制,SPAD在293 K的门控模式下工作,光子探测效率(PDE)为70%,暗计数率(DCR)为14.93 kHz,后脉冲概率(APP)为0.89%。此外,在死区时间为200 ns的主动淬灭模式下工作时,室温下实现了12.49%的PDE和72.29 kHz的DCR。

电场调控增强型背照式单光子雪崩二极管

本研究利用搭建的仿真设计平台开发了一款电场调控增强型背照式单光子雪崩二极管(SPAD)器件,通过调控SPAD雪崩区电场,进一步提升了背照式器件的光子探测效率,降低了暗计数率。仿真结果表明,本研究设计的SPAD在水平和垂直电场的协同作用下,有效提高了电子倍增效率,峰值探测效率达到50.1%,在过偏压为3 V时,暗计数率降低至764 Hz。本文对比分析了不同耗尽层厚度和P-Well半径对电场调控增强型背照式SPAD器件性能的影响,并确定了最优结构尺寸。研究结果为基于SPAD的高精度光电探测应用提供了新的技术途径,为SPAD器件在科学研究和工业应用中的进一步发展奠定了基础。

青春双歧杆菌冻干保护剂筛选及高密度冻干工艺优化

为了探究青春双歧杆菌最适冻干保护剂配方,提高工业化生产效率,作者对不同糖与蛋白质类保护剂对双歧杆菌冻干保护特性、不同结构的糖类保护剂复配及其与蛋白质复配的保护效果进行研究,同时测定复合保护剂添加其他小分子物质对冻干存活率的影响,最后优化冻干前菌泥干物质与冻干保护剂的比例,以实现高密度冻干。研究结果表明,糖(醇)类保护剂对青春双歧杆菌的保护效果普遍高于蛋白类冻干保护剂,且四糖以下小分子糖的冻干保护效果较好,其中山梨糖醇和棉籽糖效果最优,二者复配(质量比1∶1)后冻干存活率提高到56%左右;将其与蛋白质、抗坏血酸、谷胱甘肽、微量元素等小分子复配,不会提高对菌体的冻干保护效果;考虑到实际应用,将山梨糖醇、棉籽糖与乳清蛋白以质量比3∶3∶2复配以提高菌粉的疏松度;菌泥与保护剂以干物质质量比1∶1.2混合,样品干物质总质量分数为25%时,青春双歧杆菌的冻干存活率达到(77.08±5.20)%。

低计数特征的自然伽马能谱测井数据滤波方法研究

岩石天然放射性强度较弱,自然伽马能谱测井所测得的能谱计数较低,低计数特征使得地层衰变随机误差影响被放大,造成测量能谱质量差、测井曲线统计噪声大的情况。该文通过对比多种能谱滤波结果,使单深度点能谱最大程度还原准确能谱信息;利用曲线形态,针对求解的U、Th、K含量曲线进行深度域的滤波处理,综合从高噪声、低计数的数据中准确提取地层信息;利用中国石油集团测井有限公司的过钻具自然伽马能谱仪器的实测数据验证该方法的有效性。结果表明:对于计数低、谱形差的自然伽马能谱,高斯滤波、卷积滤波效果相对较好,该文提出结合这2种方法的复合滤波可以准确地还原出高保真的能谱形状;深度域的滤波,卡尔曼滤波相对自适应滤波方法有一定优势;依次经过能谱滤波和深度滤波后,结果的准确性和重复性有了大幅提升。该文所介绍的针对低计数特征的自然伽马能谱测井滤波方法,可以有效提高U、Th、K的测量精度。

SOI基横向SAMBM APD三维建模与特性研究

为更好表征器件的工作过程,为后续器件工艺制备实现提供更精确的理论支撑,采用SEN-TAURUS软件对SOI基横向多缓冲区SAM雪崩光电二极管进行三维建模仿真与特性研究。对器件的雪崩电压、光暗电流、响应度、雪崩增益、雪崩发生概率、光子探测效率以及暗计数率进行研究分析。仿真结果表明,器件雪崩电压为8.0 V,在偏置电压为4 V时,器件暗电流为5.31×10^(-16)A;当入射光波长为400 nm,光功率为0.001 W/cm^(2)时,响应度为170 A/W,增益为308.6;过偏压为1 V时,光子探测效率峰值为42.3%,暗计数率为476 Hz。

枯草芽孢杆菌生产工艺优化研究

为优化枯草芽孢杆菌(Bacillus subtilis)的发酵工艺,提高其在工业生产中的应用效率,通过调整碳氮源、无机盐添加和发酵条件(pH值、温度、通气量和转速),探究枯草芽孢杆菌最佳生产工艺。结果表明,葡萄糖和豆粕粉是最佳的碳氮源,在40 g/L和15 g/L浓度下菌量和芽孢率最优;添加无机盐能够显著增加菌量和芽孢率;pH值、温度、通气量和转速对菌体生长和芽孢有显著影响。这些发现可为枯草芽孢杆菌的商业利用提供重要的工艺指导。

Tests on Application of Soil Magnetic and Integrated Gamma Ray TLD and TC Methods to the Exploration of Sandstone-Type Uranium Deposits

This paper introduces the test results of the soil magnetic survey and the integrated gamma-ray TLD and TC methods for sandstone-type uranium exploration and describes the prospecting mechanism. The tests have proved that these approaches have yielded good results on classifying the sedimentary facies, defining the redox transitional zones and reflecting deep mineralization information. They may probably become new methods on searching for sandstone-type uranium deposits.

Studies of an event-building algorithm of the readout system for the twin TPCs in HFRS

The High-energy Fragment Separator(HFRS),which is currently under construction,is a leading international radioactive beam device.Multiple sets of position-sensitive twin time projection chamber(TPC)detectors are distributed on HFRS for particle identification and beam monitoring.The twin TPCs'readout electronics system operates in a trigger-less mode due to its high counting rate,leading to a challenge of handling large amounts of data.To address this problem,we introduced an event-building algorithm.This algorithm employs a hierarchical processing strategy to compress data during transmission and aggregation.In addition,it reconstructs twin TPCs'events online and stores only the reconstructed particle information,which significantly reduces the burden on data transmission and storage resources.Simulation studies demonstrated that the algorithm accurately matches twin TPCs'events and reduces more than 98%of the data volume at a counting rate of 500 kHz/channel.

血小板计数与血沉检测在社区结核病筛查中的价值

目的 探讨血小板计数与血沉检测在社区结核病筛查中的价值。方法 对县域医共体内公共卫生检查数据进行分析,抽取血沉(mm/h)+血小板计数(万/mm^(3))≥80者,结合既往史、现病史及胸部X线资料进行分析,观察结核病筛查结果。结果 共筛查公共卫生健康体检者111489人,男性56721人,女性54768人,共筛查到血沉(mm/h)+血小板计数(万/mm^(3))≥80者共1589例,占比1.43%。其中<18岁909例,人数比例最高,且以急性炎症性疾病居多;成人(≥18岁)680例。成人中,年龄≥80岁109例(结核病71例,占65.14%);70~79岁195例(结核病65例,占33.33%);60~69岁178例(结核病37例,占20.79%);50~59岁106例(结核病17例,占16.04%);30~49岁76例(结核病6例,占7.89%);18~29岁16例(结核病3例,占18.75%),随着年龄增大,结核病检出率呈上升趋势,各年龄段比较有显著性差异(P<0.01)。男性286例(结核病101例,占35.31%),女性394例(结核病98例,占24.87%),男性的检出率明显高于女性,有显著性差异(P<0.01)。结论 血小板计数与血沉在社区结核病筛查中有一定价值,血沉(mm/h)+血小板计数(万/mm^(3))≥80者结核病可能性大,尤其是60岁以上患者价值更大。

2023年海南省网络外卖餐饮食品微生物污染状况分析

目的:分析105批网络外卖餐饮食品微生物污染状况,为行政监管部门制定监管措施及相关标准制修订提供参考。方法:通过网络外卖App平台随机采样,按照《食品安全国家标准食品微生物学检验菌落总数测定》(GB 4789.2—2022)要求开展微生物和中心温度检测,并对检测结果不合格率进行统计学分析。结果:不同种类不合格率(χ^(2)=2.624,p> 0.05)、不同季度不合格率(χ^(2)=0.682,p> 0.05)、不同中心温度不合格率(χ^(2)=2.31,p> 0.05)均无统计学意义;菌落总数与其他微生物项目指标不合格率比较,均有极显著性差异(χ^(2)=48.451,p <0.01)。结论:本研究初步掌握了海南省网络外卖餐饮食品微生物污染的情况,为监管部门加强监管提供实验依据。