Based on first-principle,the geometric structures of intrinsic SnS2 and SnS2 doped with Ti atom replacing Sn atom were constructed,and the adsorption characteristics of five gases,namely CO,NO2,NO,SO2 and NH3 on the surfaces of the two materials were analyzed.Three adsorption sites were tested for each gas molecule and the best adsorption site was determined.The adsorption energy,transfer charge,recovery time,density of states and work function were researched to understand the adsorption mechanism.It is found that the adsorption capacities of CO and SO2 on the intrinsic SnS2 are weaker,while the adsorption capacities of NO,NO2 and NH3 on the intrinsic SnS2 are stronger.The structure of SnS2 doped by Ti atom replacing Sn atom is relatively stable,and its formation energy is-8.028 eV.At the same time,the adsorption energies of the five gas molecules on their surfaces increase to different degrees.The results show that SnS2 doped by Ti atom replacing Sn atom can improve the gas adsorption performance of SnS2 material,and its preparation method is practical,so it can be considered as a material for making gas sensors.
In this study, a flexible capacitive pressure sensor was developed, featuring a dielectric layer composed of a polydimethylsilane (PDMS)/BaTiO3/SrTiO3 3 /SrTiO 3 composite material. The electrode and dielectric layers were structured with a dual microstructure, combining diagonal and sandpaper-porous elements. Additionally, nano- barium titanate (BT) powder, known for its relatively high dielectric constant, was incorporated into PDMS, along with an appropriate amount of strontium titanate (STO), to enhance the sensor's sensitivity. The developed sensor exhibited a remarkable sensitivity of 2.681 kPa-1, -1 , with response and release times of approximately 39 ms and 61 ms, respectively. It demonstrated a low detection threshold and withstood over 5000 compression cycles, showcasing excellent repeatability. The results underscored the sensor's robust pressure-sensing performance, making it suitable for diverse applications, including human pulse monitoring, heartbeat tracking, robot arm sensing, object weight detection, and real-time healthcare monitoring.
Real-time DOA (direction of arrival) estimation of surface or underwater targets is of great significance to the research of marine environment and national security protection. When conducting real-time DOA estimation of underwater targets, it can be difficult to extract the prior characteristics of noise due to the complexity and variability of the marine environment. Therefore, the accuracy of target orientation in the absence of a known noise is significantly reduced, thereby presenting an additional challenge for the DOA estimation of the marine targets in real-time. Aiming at the problem of real-time DOA estimation of acoustic targets in complex environments, this paper applies the MEMS vector hydrophone with a small size and high sensitivity to sense the conditions of the ocean environment and change the structural parameters in the adaptive adjustments system itself to obtain the desired target signal, proposes a signal processing method when the prior characteristics of noise are unknown. Theoretical analysis and experimental verification show that the method can achieve accurate real-time DOA estimation of the target, achieve an error within 3.1° under the SNR (signal-to-noise ratio) of the X channel of −17 dB, and maintain a stable value when the SNR continues to decrease. The results show that this method has a very broad application prospect in the field of ocean monitoring.
Bone homeostasis is based on the dynamic balance of bone formation and bone resorption. An imbalance in bone homeostasis is a major contributor to many skeletal diseases, including osteoporosis. Changes in the composition and diversity of the gut microbiota (GM) are supposed to have a significant impact on bone homeostasis and are closely correlated with changes in bone mass and bone microarchitecture. The "gut-immune" axis, which is formed by the interaction between the host intestinal immune system and GM, is essential for maintaining bone homeostasis, as well as regulating the body's immunological response and maintaining immune homeostasis throughout the intestine and body. The article reviews recent advances in the study of GM, the immune system, and their synergistic impact on bone homeostasis.
Nitrocellulose microspheres have garnered extensive use in propellants and launching agents due to their inherent safety, robust flowability, and high explosive power. However, conventional preparation methods for these microspheres are often hampered by complex processes, low safety factor and poor sphericity. This study explores an innovative approach to nitrocellulose microsphere fabrication utilizing microfluidic technology. We designed and assembled two high-throughput preparation devices-a coaxial and a centrifugal device-employing 3D printing technology. Our findings demonstrate an 18-fold increase in efficiency over traditional single-pass microfluidic techniques. Additionally, we examined the impact of these devices on the microspheres' size distribution. The proposed device showcases significant advantages, including reduced cost, enhanced efficiency, and shorter production cycles, indicating promising potential for wide-scale application in nitrocellulose microsphere preparation.
心脏作为动力源,其功能是驱动血液的单向流动,它具有结构简单、工作稳定可靠、异物处理能力强、无回流等优点.基于心脏泵血的原理,研制了一种新型的机械式微泵.该微泵由微型马达、硅胶软管、瓣膜阀及壳体组成,体积仅有0.6 cm3.为了更深入地研究和测试微泵的性能,研制了基于高精度天平的流量测试系统和基于压力传感器的压强测试系统,并利用以上系统对微泵的体积流量、背压及待机状态下的反向截止压强进行了测试.实验结果表明:微泵的体积流量、背压与驱动电压呈正相关关系;在3 V直流电压驱动下,微泵的体积流量能够达到210 μL/min,背压达到27.9 kPa,而功耗仅为180 mW;同时,在待机状态下微泵的反向截止压强可达55 111.7 Pa.该微泵在医疗仪器、生物医学、微流控、芯片冷却等领域具有广阔的应用前景.
基于热声效应,对不同结构石墨烯发声器的声学性能进行研究.利用石墨烯发声器的热功率平衡方程推导出三维石墨烯泡沫发声器的近远场声压表达式,将理论计算结果与实验测试值对比,两者吻合良好,验证了理论模型的正确性;并将石墨烯泡沫与二维石墨烯薄膜进行对比,比较了四种不同结构石墨烯发声器的发声效果.结果表明,石墨烯泡沫发声效果最好,其次是铜基底石墨烯薄膜,聚对苯二甲酸乙二醇酯(PET)基底和玻璃基底的石墨烯薄膜发声效果较差;在20～10 000 Hz内,施加10 V电压、测距为1cm的条件下,石墨烯泡沫、铜基底石墨烯薄膜、PET基底石墨烯薄膜和玻璃基底石墨烯薄膜的最大单频声压级分别为59.9、53.5、47.8和38.9dB.铜基底石墨烯薄膜和石墨烯泡沫有一倍频声压产生.针对一倍频声压现象,测试铜基底石墨烯薄膜和石墨烯泡沫的振动加速度.结果表明,一倍频声压的产生与石墨烯发声器的振动有关,一倍频声压随着输入电压幅度和频率的升高而增大.该研究结果对石墨烯发声器的设计和应用具有参考价值.
以浓硫酸、高锰酸钾和双氧水作为氧化剂,以钛酸四丁酯、乙酸和双氧水为原料,可控制备不同比例氧掺杂石墨烯(OG)负载TiO2纳米球、渐变状、纳米片的不同维度的复合材料.使用扫描电子显微镜(SEM)、透射电子显微镜(TEM)、X射线衍射仪(XRD)、傅里叶变换红外(FTIR)光谱仪、紫外-可见光(UV-Vis)吸收光谱仪和X射线光电子能谱仪(XPS)等对复合样品进行了表征及分析.以活性染料X3B作为降解对象,研究了不同维度复合材料的光催化特性.结果表明,复合材料从0D/2D结构渐变至2D/2D结构,TiO2与2D氧掺杂石墨烯复合程度更加紧密,光催化性能逐步提升,2D氧掺杂石墨烯负载TiO2纳米片(TS-OG)效果最好,该样品在90 min模拟太阳光下对X3B降解率达到了 99.5％.OG的深层次氧化使得其边缘、内部存在大量含氧官能团(—COOH、—OH等),而浓硫酸处理在复合过程中起到了关键作用,有助于TiO2与OG产生更强的键合作用,促进了 TiO2表面的—OH与OG的大量含氧官能团深层次键合,使得电子传导速率增强,提高了光生电子和空穴对的分离,光催化性能显著提高,经过浓硫酸处理的TS6-OG在60 min模拟太阳光下催化降解率约是未经浓硫酸处理样品的2.7倍.
以单壁碳纳米管(SWCNT)为碳源,氯化镍为金属源,硫脲为氮源和硫源,通过水热和高温热解方法制备N,S-Ni@S@C复合材料,并对复合材料进行物理表征和电化学性能测试.结果表明,SWCNT与硫化镍、氮化镍复合的结构不仅能提高电极材料的电导率,还能提供更多的活性位点供电解质离子插入或脱出,从而显著提高电化学性能.在三电极体系下,N,S-Ni@S@C复合材料具有较高的电压窗口(1.5 V)和优异的充放电能力,在电流密度为1 A·g-1下,N,S-Ni@S@C的比电容可达162.45 F·g-1.其比电容与SWCNT相比提高了 2.61倍,与SWCNT和氯化镍复合材料(C@Ni)相比提高了 19倍,与SWCNT和硫脲复合材料(C@S@N)相比提高了 16倍.此外,以N,S-Ni@S@C复合材料为正极,商业活性炭(YP50F)为负极,组装得到非对称型超级电容器(N,S-Ni@S@C//AC).该非对称型超级电容器在功率密度为818.78 W·kg-1 时,其能量密度可达41.03 W·h·kg-1,在电流密度为1.0 A·g-1时,经过5 000次连续充放电循环后比电容仍可保持初始比电容的82％.
传统单细胞分离技术包含流式细胞术、激光捕获法和显微操作法等.然而,流式细胞术需要大量样本,且仪器体积庞大,价格昂贵;激光捕获法和显微操作法则耗时长,并且单细胞获取效率和通量较低.将热发泡喷墨技术应用于单细胞打印.利用热发泡喷嘴驱动细胞悬液,因此无需外接注射泵,并在芯片上集成大量喷嘴,实现高通量单细胞打印.首先通过OpenCV算法分割喷嘴图像,然后通过卷积神经网络(CNN)对带有单细胞的喷嘴图像进行训练和识别,最后控制喷嘴实现单细胞打印.实现了对浓度1× 106 cells/mL的CHO-K1+CDCHO和CHO-K1+DMEM/F12+FBS两种细胞悬液的16块96孔板单细胞打印,单个96孔板分选在5 min内完成.两种细胞悬液即时细胞活性损耗分别为9.1％和8.3％,单细胞打印率分别达到86.7％和87.3％,单细胞克隆率分别达到44.5％和36.9％.
CsPbCL3全无机钙钛矿纳米晶(PNC)的应用受到其弱发光、极低的光致发光量子产率(PLQY)以及长期暴露于氧气和湿气环境中稳定性差等的限制.为了解决这一问题,使用稀土金属元素铒的三价阳离子(Er3+)作为B位掺杂元素,制备出了明亮蓝紫光发射的Er3+∶CsPbCl3钙钛矿纳米晶发光材料.掺杂后的纳米晶具有最佳的形貌和发光性能:PLQY为16.7％、平均粒径约为7.98 nm、荧光发射峰蓝移至400 nm、半峰全宽仅为10.0 nm.同时该纳米晶的环境稳定性也显著提升,在测试环境(温度60℃、湿度60％RH)下存放10天后,其发光强度仍能保持初始荧光发射强度的60％以上.此工作较大程度上改善了 CsPbCl3钙钛矿纳米晶存在的问题,对于其实际应用存在重大意义.
液体毛细力驱动下的微纳组装技术可以实现胶体颗粒、纤维、薄膜和芯片等微型结构的定向运输与自组装.基于毛细力的自组装技术研究涉及多学科交叉,对微纳芯片装配、纳米材料制备和大分子聚合物制备等领域的发展有重要意义.从理论和实验两方面综述了近年来毛细力自组装技术的研究重点,介绍了毛细力和液气界面形态学的研究模型;从组装对象的结构维度、材料的刚柔特性方面分析了毛细力自组装技术的特点和组装方法,并指出结构间距、材料性质、三相接触线形状、接触角、润湿性差异和液体体积等因素对自组装的影响.最后总结了毛细力自组装技术的优缺点以及应用中存在的问题,展望了未来微纳组装技术的研究重点.
以十六烷基三甲基溴化铵(CTAB)为表面活性剂,二水合钨酸钠(Na2WO4·2H2O)为钨源,采用水热法合成纳米氧化钨(WO3).通过扫描电子显微镜(SEM)、X射线衍射仪(XRD)和X射线光电子能谱仪(XPS)对WO3的表面形貌、晶体结构和化学成分进行表征,测试其对乙二醇甲醚的气敏特性,研究CTAB对WO3的形貌、晶体结构和乙二醇甲醚气敏特性的影响.结果表明,CTAB可调控 WO3的形貌,添加质量分数5％的CTAB不仅将 WO3的形貌由不规则的纳米颗粒调控为疏松的纳米片状,而且提高了其对乙二醇甲醚的气敏特性,在最佳工作温度370 ℃下其对体积分数为1×10-4的乙二醇甲醚的响应值达15.1,并且具有良好的重复性、长期稳定性与气体选择性.最后探讨了 WO3对乙二醇甲醚的气敏机理.
设计了一种基于PT100感温元件和压力充油芯体的温度压力组合传感器.感温元件采用铠装铂电阻总体设计结构,通过快速响应封装和精度调节技术,优化了温度部分的响应时间和精度.压力传感器芯片采用绝缘体上硅(SOI)材料,解决了高温漏电流问题.基于耐高温充油封装,搭配二极管/电阻网络补偿方法,传感器实现了-55～150 ℃温区内的高精度输出.通过振动特性仿真分析,验证了传感器总体结构的稳定性和可靠性.测试结果表明,传感器温度精度达到A级,25 ℃下压力精度为-0.19％FS,线性度为-0.13％FS,温度漂移为-0.004 5％FS/℃.传感器最大外廓尺寸为Φ26 mm×85 mm,质量为130 g.
两步沉积法中胺盐的传统溶剂异丙醇会对锡基钙钛矿产生严重破坏,因此探索其他溶剂制备锡基钙钛矿非常重要.利用4-甲基-2-戊醇取代异丙醇充当胺盐的溶剂,并在胺盐中添加苯乙基溴化胺(PEABr),通过两步沉积法制备了锡基钙钛矿薄膜及全溶液工艺太阳能电池.实验结果表明,相比于异丙醇,使用4-甲基-2-戊醇作为胺盐溶剂,可降低对锡基钙钛矿的破坏作用,促进锡基钙钛矿结晶成膜,原因可能是该溶剂分子的烷基部分可以增加对羟基的空间位阻.但未添加PEABr时,制备的FASnI3薄膜存在许多针孔,器件光电转换效率(PCE)仅为0.24％;在添加摩尔占比为0.3(n(PEABr)/n(FAI+PEABr)=0.3)的PEABr时,制备的锡基钙钛矿薄膜针孔减少,致密度提高,表面形貌得到改善.利用全溶液工艺制备的基于该薄膜的太阳能电池PCE达到4.15％.该研究有助于促进两步沉积法制备锡基钙钛矿薄膜及其光伏器件的进一步发展.
微纳制造技术和微机电系统(MEMS)的迅猛发展,推动了微器件向微型化、集成化、多功能化方向发展.微器件操作末端执行器是微操作工具与微器件直接作用的部件,具有重要研究意义.综述了微器件操作末端执行器的研究现状和成果;对国内外微器件操作末端执行器进行了汇总和分类;对微器件操作末端执行器的工作原理和结构进行了介绍;基于对接触式和非接触式末端执行器研究现状的总结,分析了各种末端执行器的优势和局限.最后,讨论了微器件操作末端执行器的应用现状和面临的挑战,并对末端执行器的发展进行了展望.该研究为微器件操作末端执行器的选取和开发提供了技术参考.
为了更好地通过低成本、易操作的方法获得性能优异的忆阻器,解决忆阻器在操作电压和循环次数等方面存在的问题,制备掺杂不同质量AgI的前驱体溶液.采用低成本的低温旋涂工艺完成掺银功能层的制备,再采用蒸镀工艺实现基于Ag/Ag+掺杂有机-无机杂化钙钛矿(OIHP)/氧化铟锡(ITO)的忆阻器的制备.掺杂70 mg AgI的忆阻器与未掺杂忆阻器相比,开启电压由0.3 V降至0.13 V,循环次数提升了约20倍,高达100次以上.此外,通过限流调控,器件可同时实现多级存储功能、非易失阻变开关功能以及阈值选通功能,并且选通器双向阈值电压高度对称,开态电流达到100 μA以上,泄漏电流在1 nA以下.该研究有效地优化了忆阻器的操作电压和循环次数.
过渡金属氧化物因其理论比容量高、安全性能好,有望成为下一代锂离子电池的负极材料.但循环过程中体积变化较大、电导率较低,导致其循环性能和倍率性能较差,限制了其应用.为此,采用溶剂热法辅助热处理合成了高熵氧化物(HEO)并均匀分散于还原氧化石墨烯(rGO)载体上,将其用作锂离子电池负极材料.高熵氧化物具有较高的构型熵,有助于提高电极的循环稳定性,同时HEO/rGO复合材料大的比表面积保证了电解液的充分浸润,提高了反应速率,抑制了电极材料的团聚和体积膨胀,大大提高了电极材料的稳定性.电化学测试结果表明HEO/rGO电极在100 mA·g-1的电流密度下循环100次仍然有653.8 mA·h·g-1的比容量,表现出了良好的循环稳定性.因此,HEO/rGO复合材料被认为是一种极具开发潜力的锂离子电池负极材料.
等离激元纳米杯因其结构的非对称分布,显示出独特的电场磁场分布调制、光弯曲、强光散射和高光热转换效率等特性,其制备方法和多领域应用都获得了广泛研究.综述了等离激元纳米杯特别是金纳米杯的制备方法,包括基于微纳加工的物理制备方法和湿化学合成方法,分析对比了各种制备方法的优缺点及适用领域.介绍了等离激元纳米杯的光物理学特性,包括等离激元共振模式、吸收散射光谱特性和电场磁场特性,着重展示了纳米杯参数调谐特性.总结了等离激元纳米杯在光电器件和生物医学等领域的重要应用.最后对等离激元纳米杯的发展趋势与挑战进行了展望.
为了解决绿光量子点发光二极管(QLED)基底模式陷入光问题,首先通过在柔性聚二甲基硅氧烷基底上蒸镀铝层,自发形成了准周期褶皱结构.这种简单、有效的方法可以制作大面积的褶皱结构,所制作的褶皱结构具有随机取向和宽周期分布的特点.然后,将褶皱结构作为外结构引入到QLED中,构筑了高效的绿光QLED.与参考QLED相比,褶皱QLED的外量子效率(EQE)从12.09％增加到16.06％,提升了 32.8％;最大亮度从184 600 cd·m-2增加到226 500 cd·m-2,在不改变发光峰位的情况下实现了基底模式陷入光的高效提取,为提升绿光QLED性能提供了一种新的选择.
