Standing Surface Acoustic Wave (SSAW)‐Based Fluorescence‐Activated Cell Sorter

Microfluidic fluorescence‐activated cell sorters (μFACS) have attracted considerable interest because of their ability to identify and separate cells in inexpensive and biosafe ways. Here a high‐performance μFACS is presented by integrating a standing surface acoustic wave (SSAW)‐based, 3D cell‐focusing unit, an in‐plane fluorescent detection unit, and an SSAW‐based cell‐deflection unit on a single chip. Without using sheath flow or precise flow rate control, the SSAW‐based cell‐focusing technique can focus cells into a single file at a designated position. The tight focusing of cells enables an in‐plane‐integrated optical detection system to accurately distinguish individual cells of interest. In the acoustic‐based cell‐deflection unit, a focused interdigital transducer design is utilized to deflect cells from the focused stream within a minimized area, resulting in a high‐throughput sorting ability. Each unit is experimentally characterized, respectively, and the integrated SSAW‐based FACS is used to sort mammalian cells (HeLa) at different throughputs. A sorting purity of greater than 90% is achieved at a throughput of 2500 events s^?1. The SSAW‐based FACS is efficient, fast, biosafe, biocompatible and has a small footprint, making it a competitive alternative to more expensive, bulkier traditional FACS.     

神经网络全局势函数在多相催化中的应用

当今的多相催化研究需要新的技术和方法从原子尺度上表征活性中心结构和反应中间体。本文作者课题组近期开发了理论模拟新技术来探索催化剂活性位点结构，即基于神经网络势函数的大规模原子模拟（LASP）软件中实现的全局神经网络势函数计算方法。本文介绍了该方法可以显著降低催化体系的计算代价，而维持与密度泛函理论同一级别的计算精度，从而解决多相催化中的许多复杂问题。本文对神经网络势函数方法的实现细节和目前已实现的应用场景进行了详细介绍。神经网络势函数可以用来预测材料晶体结构，理解高压氢化条件下TiO₂表面的结构演化和确定三元氧化物ZnCrO晶相中合成气制甲醇活性位点。最后文章分析了神经网络势函数的局限性和今后可能的三个研究方向，即材料性质预测、多元素体系神经网络势函数构造和化学反应拟合。     

Preparation of transparent Y2O3 ceramic via gel casting: Realization of high solid volume via surface modification

In this article, isocyanate was adopted to modify Y₂O₃ powder for the purpose of preparing transparent Y₂O₃ ceramics via gel casting. The modification could enhance the hydration resistance of Y₂O₃ powder through the steric hindrance effect. The coating mechanism can be proved by the infrared spectrum of the surface-modified Y₂O₃ powder. Modification could not only prevent Y₂O₃ particles from reacting with water, but also prevents agglomeration between particles. The viscosity of the slurry with a solid content of 52.7 vol% is only 0.48 Pa·s at the shear rate of 100 s⁻¹, which is suitable for preparing high-density compacts by gel casting. The transmittance of the sample (1840°C × 8 h, 1 mm thickness) at 1100 nm reaches 75%. The microstructure of the sintered body is dense with the average grain size of 6.5 μm without obvious impurities nor pores. Five mol% ZrO₂-doped Y₂O₃ transparent ceramic fairing with the diameter of 5 cm without defects was successfully fabricated by gel casting (52.7 vol% solid volume) and vacuum sintering (1840°C × 8 h).     

Reduction of temperature influence in stress measurement using surface SH‐wave acoustoelasticity

Stress measurements are required to prevent collapse accidents of structures. Surface SH‐wave acoustoelasticity can measure principal stress difference nondestructively and easily. Currently, surface SH‐wave acoustoelasticity can measure with high precision using a T‐type surface SH‐wave sensor in ideal environments such as in the laboratory. However, in actual environments, it cannot be measured with high precision due to change in the temperature of the specimen. In this paper, temperature dependence of surface SH‐wave acoustoelastic constants was verified to investigate the influence of specimen temperature on surface SH‐wave acoustoelasticity. In addition, the measuring system of surface SH‐wave acoustoelasticity using a cross T‐type surface SH‐wave sensor to reduce the influence of specimen temperature was developed.     

Temperature-responsive culture surfaces for insect cell sheets to fabricate a bioactuator

ABSTRACT

For the first time, we have fabricated insect-derived cell sheets by using temperature-responsive culture surfaces having a phase-transition temperature below 25°C. We prepared the temperature-responsive cell culture surfaces (tissue culture polystyrene, TCPS) by grafting a copolymeric gel consisting of hydrophobic N-tert-butylacrylamide (tBAAm) and N-isopropylacrylamide (IPAAm) units. First, to characterize the hydrophilic and hydrophobic properties of the copolymeric gel-grafted surfaces, static water contact angles of each surface were measured at various temperatures. By increasing the amount of tBAAm in the grafted copolymeric gel, the transition temperature of the gel was shifted to lower temperatures. At 25°C, the grafted copolymeric gel was dehydrated, and the insect-derived cells (AeAl2 cells) adhered on all the copolymeric gel-grafted surfaces. At 20°C, AeAl2 cells cannot adhere on the P(IPAAm-1.62tBAAm)-TCPS surface (the initial molar ratio of IPAAm and tBAAm (tBAAm?=?1.62 mol%)) better than on other surfaces (TCPS and tBAAm?=?4.88, 8.17 mol%). These two findings implied that the lower critical solution temperature of the copolymeric gel-grafted-TCPS existed from 20°C to 25°C. The laminin-coated P(IPAAm-1.62tBAAm)-TCPS surface showed temperature-dependent cell attachment and detachment properties, while AeAl2 cells were not detached from the extracellular matrix uncoated P(IPAAm-1.62tBAAm)-TCPS surface. AeAl2 cells and insect muscle cells were harvested as the respective sheets.     

Investigations of geometrical structure and morphology of samples made of hard machinable materials after wire electrical discharge machining and vibro‐abrasive finishing

In this article the results concerned influence of processing conditions of the wire electrical discharge machining and vibro‐abrasive machining on the surface layer and morphology of samples made of hard machinable materials used in aircraft industry like: Titanium 5553 β, Inconel 617, Hastelloy X and Magnesium AZ31 have been presented. For this purpose the cubic and cylindrical samples made of hard machinable alloys have been prepared using optimal electric parameters of wire‐cut electrical discharge machining and finally they have been polished using circular vibratory finishing technology and different ceramic shaped stones.     

Indoor boundary layer chemistry modeling

Ozone (O₃) chemistry is thought to dominate the oxidation of indoor surfaces. We consider the hypothesis that reactions taking place within indoor boundary layers result in greater than anticipated hydroxyl radical (OH) deposition rates. We develop models that account for boundary layer mass‐transfer phenomena, O₃‐terpene chemistry and OH formation, removal, and deposition; we solve these analytically and by applying numerical methods. For an O₃‐limonene system, we find that OH flux to a surface with an O₃ reaction probability of 10^?8 is 4.3 × 10^?5 molec/(cm² s) which is about 10 times greater than predicted by a traditional boundary layer theory. At very low air exchange rates the OH surface flux can be as much as 10% of that for O₃. This effect becomes less pronounced for more O₃‐reactive surfaces. Turbulence intensity does not strongly influence the OH concentration gradient except for surfaces with an O₃ reaction probability >10^?4. Although the O₃ flux dominates OH flux under most conditions, OH flux can be responsible for as much as 10% of total oxidant uptake to otherwise low‐reactivity surfaces. Further, OH chemistry differs from that for ozone; therefore, its deposition is important in understanding the chemical evolution of some indoor surfaces and surface films.     

Remediation of oil spill polluted water from Niger Delta Nigeria by sorption onto ammonium sulfate modified Dialium guineense seed husk

The abstraction of crude oil molecules from aqueous solution (produced water) and from real petroleum polluted water (collected from River State, Nigeria) by Dialium guineense Seed Husk (DGSH) and its ammonium sulfate functionalized form (AS-DGSH) was studied using a batch technique. The sorbents were characterized using Fourier transform infrared (FTIR), BET surface area analysis and the Scanning electron microscopy (SEM). Crude oil characterization revealed a light crude oil based on the API gravity of 35.6⁰. The Langmuir and Freundlich models gave good fits for crude oil sorption on DGSH and AS-DGSH respectively. The sorbents were found to remove over 50% of crude oil from the real polluted water at the natural pH of 6.1 and showed increase in removal with increase in sorbent dose. The potential of DGSH and its ammonium sulfate modified derivative as effective low cost sorbents for oil spill treatment was established.