Biosensors and rapid diagnostic tests on the frontier between analytical and clinical chemistry for biomolecular diagnosis of dengue disease: a review

The past decades have witnessed enormous technological improvements towards the development of simple, cost-effective and accurate rapid diagnostic tests for detection and identification of infectious pathogens. Among them is dengue virus, the etiologic agent of the mosquito-borne dengue disease, one of the most important emerging infectious pathologies of nowadays. Dengue fever may cause potentially deadly hemorrhagic symptoms and is endemic in the tropical and sub-tropical world, being also a serious threat to temperate countries in the developed world. Effective diagnostics for dengue should be able to discriminate among the four antigenically related dengue serotypes and fulfill the requirements for successful decentralized (point-of-care) testing in the harsh environmental conditions found in most tropical regions. The accurate identification of circulating serotypes is crucial for the successful implementation of vector control programs based on reliable epidemiological predictions. This paper briefly summarizes the limitations of the main conventional techniques for biomolecular diagnosis of dengue disease and critically reviews some of the most relevant biosensors and rapid diagnostic tests developed, implemented and reported so far for point-of-care testing of dengue infections. The invaluable contributions of microfluidics and nanotechnology encompass the whole paper, while evaluation concerns of rapid diagnostic tests and foreseen technological improvements in this field are also overviewed for the diagnosis of dengue and other infectious and tropical diseases as well.     

基于Hoek-Brown准则的破裂围岩应力分析

深部煤矿巷道在高围压的作用下,围岩普遍出现破裂,而且围岩破裂范围在扩大的同时,往往出现继续破坏的现象,并形成不同的分区.论文针对长的圆形巷道,将围岩分成破裂、塑性和弹性三个区域,采用Hoek-Brown准则,进行非关联弹塑性分析,获得了其应力和变形的封闭解析解,并说明该解析解是不唯一的.通过利用在弹塑交界处应力连续的条件、以及在破裂和塑性交界处径向应变连续的条件,获得了确定围岩破裂区和塑性区半径的解析算式.最后,通过算例并分析了破裂区和塑性区应力和应变的分布特点、以及破裂区范围的影响.利用所获得的结果,可以为巷道的稳定性分析以及支护设计提供理论依据.     

一维河网泥沙输移模式研究

推导了一种显式的河网 泥沙输移递推计算方法, 该方法在水动力学计算结果所确定的汊点类型基础上, 直接计算每 个河段中逐个节点的不平衡泥沙输沙过程以及悬沙和床沙的级配调整, 克服了传统方法中必 须通过首末断面含沙量关系确定河网悬沙矩阵求解的困难. 将该泥沙输移模式的一维河网水 沙数学模型, 应用于长江三峡下游荆江-洞庭湖河网区域, 并取得了较好的计算结果.在模型 验证之后, 进一步讨论了采用新的泥沙输移计算模式和原有泥沙输移计算模式在计算 时间上和计算内容方面的差别.     

攀枝花地区冰期膨胀土的工程特性研究

攀枝花地区冰期膨胀土生成于二冰期晚期中更新统冰期,通过室内和现场物理力学试验和分析,揭示攀枝花地区冰期膨胀土的物理力学性质具有很大的离散性,其性质受土体的矿物成分、含水率、裂隙面、埋藏深度、级配、试验条件等因素、条件的影响。试验研究表明:膨胀土中的裂隙面按光滑程度不相同,可分为两种类型,即光滑裂隙面和光滑擦痕裂隙面; 粗粒矿物对胀缩性影响不大,而细粒矿物对胀缩性影响较大; 裸露或近地表,土层风化剧烈,裂隙较发育,膨胀力度就稍大; 同一地区的膨胀土,蒙脱石含量愈高,自由膨胀率愈大,其膨胀等级就愈高; 不同场地内的膨胀土其物理力学性质指标存在一些差异,但差异性较小; 攀枝花冰期膨胀土层的黏粒含量并不大; 不同场地内的膨胀土抗剪强度值变化较大,同一场地内的膨胀土抗剪强度值有起伏; 攀枝花冰期膨胀土多数呈硬塑-坚硬状,自然状态下其抗压变形能力较好,在浸水饱和状态下,膨胀土的承载力几乎成倍数下降。     

母岩高铀离子型稀土矿采区的放射性污染风险浅析

铀与稀土元素同属大离子亲石元素,尤其与钇组稀土关系更密切,因此南岭高铀花岗岩往往同时是铀和离子型重稀土矿床的成矿母岩。国内外研究资料表明,高铀花岗岩中的铀主要以原生铀的形式存在于晶质铀矿中,在强烈风化过程中大部分发生活化转移,而采矿活动对此有显著促进作用;国外众多含铀湿地的发现及其研究资料表明,山区湿地是铀的"高效过滤器"和"沉淀池",花岗岩风化转移到水体中的微量铀经长期累积,可在湿地富有机质土壤和沉积物中富集至(3000~4000)×10^-6,而采矿和农垦活动可将湿地经几千年累积富集起来的铀释放到居民的生活环境中,因而被视为是一种环境风险。因此建议加强母岩高铀离子型稀土矿区的湿地放射性调查和环境保护,以保障湿地对重金属的天然过滤功能,避免湿地束缚铀的释放,这对保护矿区水质和生态环境都具有重要意义。     

Nonlinear optical absorption and fluorescence of phosphine-substituted bithiophenes in the violet-blue spectral region

The nonlinear optical absorptions of two 5,5′-bis(diphenylphosphino)-2,2′-bithiophene derivatives, Ph₂(X)P(C₄H₂S)₂P(X)Ph₂ (X = O, 1; S, 2), have been investigated by direct transmission measurement with both picosecond and nanosecond laser pulses from 420 nm to 480 nm. Saturated dichloromethane solutions of 1 and 2 exhibit strong nonlinear optical absorptions in this violet-blue spectral region with that of 2 being stronger at all wavelengths. In the picosecond regime, at 420 nm, the transmittance rapidly falls to 50% when the incident fluence is 0.22 J/cm² for 1 and 0.11 J/cm² for 2. Two-photon absorption appears to be the primary mechanism for this nonlinear absorption. The two-photon absorption coefficients β for 1 (2.1 cm/GW) and 2 (4.4 cm/GM) were obtained by fitting the measurement of transmittance as the function of incident beam intensity at 420 nm. These β values are comparable with some of the best results obtained for organic materials in the green, red and infrared spectral region. Both compounds also show fluorescence with an emission peak at 390 nm for 1 and 400 nm for 2. The fluorescence of 1 is considerably stronger than is that of 2. The combination of the wide band gap and strong fluorescence emission of 1 makes it a promising candidate as a host material for blue organic light emitting diodes.     

基于微粒群区域搜索和小波评价的差分式自动聚焦

为进一步提高图像法自动聚焦的性能,提出了一种差分式提取图像边缘的方法,并构造了图像清晰度的小波评价函数,同时利用微粒群（PSO）算法对聚焦区域进行快速搜索。首先,介绍了差分式边缘提取方法及其优势,给出了一种评价区域的选取判据以及基于PSO的高效搜索方法;然后,对小波评价函数参数进行了比较分析和优选;最后,与传统方法进行了对比实验。结果表明,由于采用了差分式提取方法以及新的自适应聚焦窗口和评价函数,聚焦曲线较传统方法具有更高的调焦分辨率,PSO算法的使用使聚焦速度提高了约170 ms,聚焦精度约为2.3μm,同时调焦效果不受初始位置的影响。     

一种基于移动预测的无线传感器网络动态拓扑管理机制

拓扑管理是节省无线传感器网络能量消耗的主要方法之一.通常采用的拓扑管理是静态的.即在整个网络范围内通过定期让冗余节点休眠来节能.但在诸如移动目标定位跟踪的应用场景中.静态拓扑管理会造成较大的能量消耗的浪费.提出一种动态拓扑管理机制,利用移动预测技术在移动目标的附近动态构造拓扑管理区域,并只在该区域内实施拓扑管理,而让区域之外的大部分节点休眠.分析了动态拓扑管理的性能并通过仿真比较了动态拓扑管理与其他相关机制的能量消耗.     

A Trust-Region Algorithm for Global Optimization

We consider the global minimization of a bound-constrained function with a so-called funnel structure. We develop a two-phase procedure that uses sampling, local optimization, and Gaussian smoothing to construct a smooth model of the underlying funnel. The procedure is embedded in a trust-region framework that avoids the pitfalls of a fixed sampling radius. We present a numerical comparison to three popular methods and show that the new algorithm is robust and uses up to 20 times fewer local minimizations steps.     

一类LC1规划问题的超线性收敛ODE信赖域算法

In this paper, a new trust region algorithm for unconstrained LC1 optimization problems is given. Compare with those existing trust regiion methods, this algorithm has a different feature: it obtains a stepsize at each iteration not by soloving a quadratic subproblem with a trust region bound, but by solving a system of linear equations. Thus it reduces computational complexity and improves computation efficiency. It is proven that this algorithm is globally convergent and locally superlinear under some conditions.