Ambient mass spectrometry: Direct analysis of dimethoate,tebuconazole, and trifloxystrobin on olive and vine leaves by desorption electrospray ionization interface

A new field of application for a relatively new mass‐spectrometric interface such as desorption electrospray ionization was evaluated. For this purpose, its behavior was tested versus quantitative analysis of dimethoate, trifloxystrobin, and tebuconazole directly on olive and vine leaves surface. The goal was workers exposure assessment during field re‐entry operations since evidence suggests an association between chronic occupational exposure to some agrochemicals and severe adverse effects. Desorption electrospray ionization gave good response working in positive ionization mode, while numerous test were necessary for the choice of a unique blend of spray solvents suitable for all 3 substances. The best compromise, in terms of signal to noise ratios, was obtained with the CH₃OH/H₂O (80:20) mixture. The obvious difficulties related to the impossibility to use the internal standard were overcome through an accurate validation. Limits of detection and quantitation, dynamic ranges, matrix effects, and intraday precisions were calculated, and a small monitoring campaign was arranged to test method applicability and to evaluate potential dermal exposure. This protocol was developed in work safety field, but after a brief investigation, it was find to be suitable also for food residue evaluation.     

Numerical study of flow characteristics of the high speed train entering into a tunnel

When a high speed train enters into a tunnel, the aerodynamic forces severely change and, consequently, the stability and performance significantly deviate from the value of design point which is usually set at cruising speed on the plain ground. The compression wave is also generated ahead of the train due to the piston-like action of tunnel entry motion. The present work is to understand the flow field such as variation of aerodynamic forces and generation of compression wave during tunnel entry motion by applying three-dimensional unsteady Navier–Stokes equation solver. To account for the relative motion of stationary tunnel and moving train, the sliding multi-block method has been implemented.     

Underwater acoustics and cavitating flow of water entry

The fluid mechanics of water entry is studied through investigating the underwater acoustics and the supercavitation. Underwater acoustic signals in water entry are extensively measured at about 30 different positions by using a PVDF needle hydrophone. From the measurements we obtain (1) the primary shock wave caused by the impact of the blunt body on free surface; (2) the vapor pressure inside the cavity; (3) the secondary shock wave caused by pulling away of the cavity from free surface; and so on. The supercavitation induced by the blunt body is observed by using a digital high-speed video camera as well as the single shot photography. The periodic and 3 dimensional motion of the supercavitation is revealed. The experiment is carried out at room temperature. The project supported by the “BaiRen Plan” of Chinese Academy of Sciences     

射流冲击水垫塘入射点旋涡掺气特性的研究

通过实验研究了不掺气射流冲击水垫塘入射点旋涡掺气的特性。实验结果表明：空气从射流入射点被卷入后，沿射流剪切层扩散；入射点掺气浓度随水垫深度的减小而增加；剪切层内水气混合体的流速分布具有误差函数形式；在剪切层内、外区，其掺气浓度分别符合高斯分布，与理论计算吻合良好。另外，还从理论上导出了射流入射点附近水气混合层的厚度，并给出了计算掺气量的公式。     

Global stability of a virus dynamics model with cure rate and absorption

In this paper, we investigate a mathematical model which takes account the cure of infected cells and the loss of viral particles due to the absorption into uninfected cells. The global stability of the model is determined by using the direct Lyapunov method for disease-free equilibrium, and the geometrical approach for chronic infection equilibrium.     

Characterization of human papillomavirus by capillary isoelectric focusing with whole‐column imaging detection

CIEF with whole‐column imaging detection (WCID) can be a useful tool for the characterization and identification of human papillomavirus (HPV). This article is the initial report of the determination of the pI of HPV by CIEF‐WCID method. In this study, components of the assay selected for optimization were ampholytes, additives, methylcellulose concentration, HPV concentration, salt concentration, and focusing time. Then the optimization CIEF‐WCID method was validated for HPV 16L1 and HPV 18L1. As a result, a precise method to analyze the pI values of HPVs was achieved with RSD < 1.0%. The HPV peak pattern was reproducible. CIEF‐WCID had great potential for HPV quality control, as WCID eliminated the mobilization step required by the conventional single‐point detection. In the example, the five HPVs displayed pI values of 8.43 ± 0.06 (n = 10; HPV 6L1), 8.70 ± 0.04 (n = 10; HPV 11L1), 7.94 ± 0.05 (n = 18; HPV 16L1), 7.57 ± 0.04 (n = 18; HPV 18L1), and 8.45 ± 0.05 (n = 10; HPV 58L1). This CIEF‐WCID platform could be a powerful analytical tool for characterization, process development support, release testing, and stability study in pharmaceutical industry.     

高速斜入水和水平入水气炮水箱实验系统

为开展模型高速斜入水和水中高速航行的水流场实验研究,研制了立式和卧式气炮与水箱组合的实验系统。通过快速阀和活塞阀控制气炮激发和驱动状态,一级气炮采用高压空气直接驱动弹托和模型,二级气炮采用高压空气驱动重活塞压缩使集气腔中产生高压气体,再驱动弹托和模型达到预定速度。通过调节水箱和发射管角度,使高速模型斜入水或水平入水。其中,立式可变发射角二级气炮可发射质量1～1000 g的模型至2500 m/s最大速度,卧式一级气炮可发射质量1～100 kg的模型至300 m/s最大速度。和小气室、高燃气压力火药驱动方式相比,新型气炮采用大体积、中低驱动压力气室,高压气体更接近等熵膨胀做功,调节高压气体压力,能较好地满足模型质量和速度的宽范围要求。结合光反射通断法测速、高速摄影和阴影流场显示等测量技术,得到立式气炮压缩管重活塞运动速度、压缩管末端压力时间曲线和模型倾斜与水平入水的流场阴影图像。结果表明:重活塞速度在膜片破裂前和理论计算值符合较好,但破膜后差异较大。立式气炮流场阴影图像反映了模型斜入水产生的空中和水中激波以及在气水界面的反射激波、空泡形成和侧向气水界面的破碎与飞溅等现象。从卧式气炮的模型水平入水阴影图像提取气泡轮廓,清楚地看出尾部气泡气水界面的波动和失稳。和商业计算软件Fluent计算结果相比,空泡上游区域基本重合,但尾流区域强湍流导致两者存在明显差异。和水洞实验相比,气炮水箱实验系统近真实地再现高速入水过程伴随的冲击和动态空化等物理现象和模型尺度效应。     

The inverse balayage problem for Markov chains,part II

This paper continues the study of the inverse balayage problem for Markov chains. Let X be a Markov chain with state space $\text{A ? B}{}_2$, let v be a probability measure on B₂ and let M(v) consist of probability measures μ on A whose X-balayage onto B₂ is v. The faces of the compact, convex set M(v) are characterized. For fixed μ?M(v) the set M(μ,v) of the measures ? of the form $\text{?(·) = P}{}^{\mathrm{\mu }}\text{{X(S) ? ·}}$, where S is a randomized stopping time, is analyzed in detail. In particular, its extreme points and edge are explicitly identified. A naturally defined reversed chain X, for which v is an inverse balayage of μ, is introduced and the relation between X and X^ is studied. The question of which $\text{? ? M(μ, v)}$ admit a natural stopping time $\text{S}{}_{\mathrm{?}}$ of X (not involving an independent randomization) such that $\text{?(·) = P}{}^{\mathrm{\mu }}\text{{X(S}{}_{\mathrm{?}}\text{) ? ·}}$, is shown to have rather different answers in discrete and continuous time. Illustrative examples are presented.     

Description of Virus Capsid Structures with Methods from Inorganic Solid State Chemistry

The fundamental theorem of algebra and the Hermites provide unique methods to describe virus capsids. Giant virus structures are described in the Rossmann's series that contains the PBCV‐1, and also a hypothetical Mimi virus structure. The HIV core structure given by Mark Yeager and Barbie Ganser‐Pornillos is described as composed of capsid members of the Blue Tongue series.     

Tangential flow filtration for virus purification

Purification of virus particles and viral vectors for viral vaccines and gene therapy applications is a major large-scale separations challenge. Purification of parvovirus particles such as adeno-associated virus, the leading candidate for gene therapy applications, is particularly challenging given their small size, typically 18–26 nm. We have investigated the use of ultrafiltration for purification of Aedes aegypti densonucleosisvirus, a mosquito parvovirus.