Collimating micro-lens fiber array for noncontact near-infrared diffuse correlation tomography

Near-infrared diffuse correlation spectroscopy/tomography (DCS/DCT) has recently emerged as a noninvasive measurement/imaging technology for tissue blood flow. In DCT studies, the high-dense collection of light temporal autocorrelation curves (g₂(τ)) via fiber array are critical for image reconstruction of blood flow. Previously, the camera-based fiber array limits the field of view (FOV), precluding its applications on large-size human tissues. The line-shape fiber probe based on lens combination, which is predominantly used in current DCT studies, requires rotated-scanning over the surface of target tissue, substantially prolonging the measurement time and increasing the system instability. In this study, we design a noncontact optical probe for DCT based on collimating micro-lens fiber array, termed as FA-nc-DCT system. For each source/detector fiber, a single optical path was collimated by coupling with one micro-lens in the fiber array that is integrated in a square-shape base. Additionally, an 8×8 optical switch is used to share the hardware laser and detectors without spatial scanning. The FA-nc approach for the precise collection of g₂(τ) curves was validated through a speed-varied phantom experiment and the human experiments of cuff occlusion, from which the expected value of the blood flow index (BFI) was obtained. Furthermore, the flow anomaly in the phantom and the ischemic muscle in human were accurately reconstructed from the FA-nc-DCT system, which is combined with the imaging framework based on the Nth-order linear algorithm that we recently created. Those outcomes demonstrated the great potential of FA-nc-DCT technology for fast and robust imaging of various diseases such as human breast cancers.     

Exploration of D022-Type Al3TM(TM = Sc,Ti, V,Zr, Nb,Hf, Ta): Elastic Anisotropy,Electronic Structures,Work Function and Experimental Design

The structural properties, elastic anisotropy, electronic structures and work function of D0₂₂-type Al₃TM (TM = Sc, Ti, V, Y, Zr, Nb, La, Hf, Ta) are studied using the first-principles calculations. The results indicate that the obtained formation enthalpy and cohesive energy of these compounds are in accordance with the other calculated values. It is found that the Al₃Zr is the most thermodynamic stable compound. The mechanical property indexes, such as elastic constants, bulk modulus, shear modulus, Young’s modulus, Poisson’s ratio, and Vickers hardness are systematically explored. Moreover, the calculated universal anisotropic index, percent anisotropy and shear anisotropic factors of D0₂₂-type Al₃TM are analyzed carefully. It demonstrates that the shear modulus anisotropy of Al₃La is the strongest, while that of Al₃Ta is the weakest. In particular, the density of states at Fermi level is not zero, suggesting that these phases have metal properties and electrical conductivity. More importantly, the mechanisms of correlation between hardness and Young’s modulus are further explained by the work function. Finally, the experimental design proves that D0₂₂-Al₃Ta has an excellent strengthening effect.     

肝硬化患者的腹腔镜胆囊切除术

目的:总结肝硬化患者腹腔镜胆囊切除术的临床经验。方法:对20例肝硬化腹腔镜胆囊切除术患者的临床资料进行了回顾性分析。结果:20例均成功地完成了腹腔镜胆囊切除术,术后无出血、肝功能衰竭、胆道损伤病例,无手术死亡病例。结论:肝硬化患者进行腹腔镜胆囊切除术要严格掌握手术适应证,并要认真做好围手术期处理。     

537例经产妇分娩方式及难产因素分析

目的:分析经产妇分娩方式及难产因素,探讨经产妇各项剖宫产指征的合理性,寻求降低经产妇剖宫产率的对策,提高经产妇母儿安全水平。方法:将1999年3月～2009年2月无妊娠合并症的537例经产妇按分娩时间分为前5年组和后5年组,对其基本特征、分娩方式、难产主要因素进行分析比较。结果:后5年组与前5年组比较,经产妇年龄呈明显增加趋势;自然分娩率、阴道助产率、臀位助产率降低,剖宫产率增高;臀位妊娠发生率无变化,瘢痕子宫比例明显增加,其剖宫产率均明显增高。结论:应加强经产妇的围产期保健及高危妊娠管理,重视有阴道助产史和胎儿体重较前次分娩新生儿体重有较大增加的孕妇的产程,避免发生母儿并发症;通过降低臀位妊娠和瘢痕子宫经产妇的剖宫产率,可以合理降低经产妇的剖宫产率。     

无机金属配合物与DNA的相互作用问题

综述了金属配合物与DNA相互作用的方式和机理,总结其相互作用的一般规律,对探索配合物在抗肿瘤药物、分子生物学、生物工程技术及其它领域的应用具有重要的意义。     

文化对认知的影响

对文化的再认和深入理解对神经心理学至关重要。本文从两方面讨论文化对认知的影响。提出理论性的结构框架,结合认知性别差异研究新进展,阐明除大脑神经心理状态之外,文化是影响个体认知、行为的关键因素之一。     

Prevention of treatable infectious diseases: A game-theoretic approach

We model outcomes of voluntary prevention using an imperfect vaccine, which confers protection only to a fraction of vaccinees for a limited duration. Our mathematical model combines a single-player game for the individual-level decision to get vaccinated, and a compartmental model for the epidemic dynamics. Mathematical analysis yields a characterization for the effective vaccination coverage, as a function of the relative cost of prevention versus treatment; note that cost may involve monetary as well as non-monetary aspects. Three behaviors are possible. First, the relative cost may be too high, so individuals do not get vaccinated. Second, the relative cost may be moderate, such that some individuals get vaccinated and voluntary vaccination alleviates the epidemic. In this case, the vaccination coverage grows steadily with decreasing relative cost of vaccination versus treatment. Unlike previous studies, we find a third case where relative cost is sufficiently low so epidemics may be averted through the use of prevention, even for an imperfect vaccine. However, we also found that disease elimination is only temporary—as no equilibrium exists for the individual strategy in this third case—and, with increasing perceived cost of vaccination versus treatment, the situation may be reversed toward the epidemic edge, where the effective reproductive number is 1. Thus, maintaining relative cost sufficiently low will be the main challenge to maintain disease elimination. Furthermore, our model offers insight on vaccine parameters, which are otherwise difficult to estimate. We apply our findings to the epidemiology of measles.     

Interfacial modification of basalt fiber filling composites with graphene oxide and polydopamine for enhanced mechanical and tribological properties

Due to the chemical inertness of the basalt fiber (BF) surface, the weaker interfacial bonding between BF and polymer matrices will seriously affect the further application of basalt fiber enhanced composites. In this study, a continuous and compact graphene oxide (GO) layer was grafted onto the surface of basalt fiber (BF) using biomimetic polydopamine (PDA) as a bridge to improve the mechanical and tribological properties of polyamide 6. The impact and flexural strength of the PA6 composites filled by the GO grafting BF (GO–PDA–BF/PA6) indicated that the introduction of GO has made a larger improvement in interface bonding performance between BF and PA6 matrix. The friction and wear tests showed the wear rate of the GO–PDA–BF/PA6 composite decreased by 51% compared with BF/PA6 composites and it also showed the best wear resistance and load-carrying capacity under various applied loads and sliding speeds, explained by the improved interface bonding between GO–PDA–BF and PA6 matrix and the anti-wear protective transfer film formed by GO in the worn surface. This study provided a considerable flexibility strategy of tailoring the interfacial compatibility between reinforcement and matrix for effectively improving the comprehensive performance of composites.

Graphene oxide was grafted onto the surface of basalt fiber via polydopamine to enhance the interfacial adhesion of PA6 composites.     

在CPS微球表面实现N-羟基邻苯二甲酰亚胺的同步合成与固载及固体催化剂催化氧化性能初探

通过分子设计的构思,仅通过两步大分子反应,便实现了N-羟基邻苯二甲酰亚胺(NHPI)在交联聚苯乙烯(CPS)微球表面的同步合成与固载,并制得了非均相催化剂微球CPS-NHPI。以氯化偏苯三酸酐(TMAC)为试剂、Lewis酸为催化剂,通过Friedel-Crafts酰基化反应,先将邻苯二甲酸酐(PA)基团键合在CPS微球表面,得到改性微球CPS-PA;再与盐酸羟胺进行酰亚胺反应,制备出固载有NHPI基团的非均相催化剂微球CPS-NHPI。重点研究了CPS微球表面发生Friedel-Crafts酰基化反应的影响因素。采用红外光谱(FT-IR)及扫描电子显微镜(SEM)等对微球CPS-NHPI进行表征,将微球CPS-NHPI分别用于分子氧氧化乙苯及环己烷两种烃类物质的氧化过程,初步考察了该微球的催化活性。研究结果表明,对于微球CPS与TMAC之间的Friedel-Crafts酰基化反应,适宜的溶剂为氯仿与N,N-二甲基乙酰胺(DMAC)混合溶剂(氯仿与DMAC的体积比为7:3),适宜的Lewis酸催化剂为SnCl₄。初步探索实验表明,催化剂微球CPS-NHPI与Co(OAc)₂ 所构成的共催化体系,在分子氧氧化乙苯及环己烷的催化氧化过程中,都表现出了良好的催化活性,温和条件下,反应35 h时乙苯氧化为苯乙酮的转化率可达37%,反应30 h时环己烷氧化为环己酮的转化率可达21%。     

在非水介质中用表面引发接枝聚合法制备接枝微粒PHEMA-SiO2及其对槲皮素的氢键吸附性能

首先,将偶联剂γ-巯丙基三甲氧基硅烷(MPMS)上的巯基(-SH)键合在微米级硅胶(SiO₂)微粒表面,得到了改性微粒MPMS-SiO₂。在非水溶剂N,N-二甲基甲酰胺(DMF)中,使溶液中的过氧化苯甲酰(BPO)与改性微粒MPMS-SiO₂表面的巯基构成表面引发体系(-SH/BPO),于非水介质中在硅胶微粒表面实现了甲基丙烯酸羟乙酯(HEMA)的接枝聚合,成功制备出接枝微粒PHEMA-SiO₂,接枝度高达28 g/100 g。采用红外光谱(FT-IR)、热重分析(TG)及扫描电子显微镜(SEM)等手段对PHEMA-SiO₂进行了表征,研究了主要因素对HEMA表面引发接枝聚合的影响规律。在此基础上探索研究了PHEMA-SiO₂对槲皮素(Quercetin)的氢键吸附作用。研究结果表明:-SH/BPO引发体系可以顺利地引发HEMA在非水介质中的接枝聚合,适宜的温度为65℃,适宜的BPO用量为单体质量的1.0%。PHEMA-SiO₂与槲皮素分子之间会产生多位点普通氢键与π型氢键两种氢键相互作用,使PHEMA-SiO₂对槲皮素具有强吸附能力。溶剂分子对槲皮素的竞争吸附以及温度的升高均可使槲皮素在极性溶剂或质子性溶剂中吸附容量下降。