Crystal growth and scintillation properties of (NaxCa1−2xLux−yNdy)F2 single crystals

Na_xCa_1−2xLu_x−yNd_yF₂ single crystals were grown from the melt using the precise atmosphere control type Micro-Pulling-Down (μ-PD) method to investigate their potential as a vacuum-ultraviolet (VUV) scintillators. The grown crystals were single-phase materials with fluorite-type structure (Fm-3m, Z = 4) as confirmed by XRD. The crystals demonstrated 80-90% transmittance above 200 nm wavelength and Nd³⁺ 5d-4f luminescence (when exited by X-ray) observed around 185 nm. The radioluminescence measurements under 5.5 MeV α-ray excitation (²⁴¹Am) demonstrated the light yield of 48 [Ph/5.5 MeV-α] and the decay time of 6.4-7.7 ns.     

Drawing slicing graphs with face areas

We consider orthogonal drawings of a plane graph G$G$ with specified face areas. For a natural number k$k$, a k$k$-gonal drawing of G$G$ is an orthogonal drawing such that the boundary of G$G$ is drawn as a rectangle and each inner face is drawn as a polygon with at most k$k$ corners whose area is equal to the specified value. In this paper, we show that every slicing graph G$G$ with a slicing tree T$T$ and a set of specified face areas admits a 10-gonal drawing D$D$ such that the boundary of each slicing subgraph that appears in T$T$ is also drawn as a polygon with at most 10 corners. Such a drawing D$D$ can be found in linear time.     

基于交互式叠加注意力网络的实体属性情感分类

当上下文中单词的情感对给定属性敏感时,仅通过注意力建模无法解决情感分类性能下降的问题。提出一种基于交互式叠加注意力(Attention-Over-Attention,AOA)网络的属性级情感分类模型。模型在词向量层用BERT代替传统静态词向量表示;用LSTM分别提取属性和上下文中单词的隐藏语义;用AOA网络计算属性和上下文中每个单词的注意力权重;将权重与对应的隐藏语义状态做点积分别得到属性和上下文的最终特征表示,拼接两个特征表示用来分类。研究并分析模型中词向量和属性单独建模对情感分类结果的影响。实验表明,该模型较其他LSTM结合注意力机制的模型在准确率和F1值上都有显著提高。     

Premixed flame propagating into a narrow channel at a high speed, part 1: Flame behaviors in the channel

This paper deals with the transient behavior of a flame flowing into a narrow channel from a chamber filled with a propane---air mixture.

The flame was observed through direct or schlieren high speed photography, and at the same time the arrival at the entrance and exit of the channel were detected by ion gaps. From the experimental results it was found that in some cases the flame extinguished or hesitated in the channel before passing through. These behaviors were dependent on the equivalence ratio of the mixture, the channel width, and the flame inflow velocity.

Flame standstill in the channel is assumed to be caused by continuous quenching of hot reacting gas due to turbulent mixing with cold unburned gas at the contraction region established near the entrance of the channel. For any specific mixture, when the channel entrance is rounded or the inflow velocity is low, the minimum width of the channel for which a flame will run through without any retardation becomes smaller compared with the case of a sharp-edged entrance or a high inflow velocity. On the contrary, the minimum width of the channel for which a flame cannot pass through does not depend on the corner roundness of the channel entrance or the inflow gas velocity.     

Numerical Investigation on Turbulence and Bubbles Distribution in Bubbly Flow Under Normal Gravity and Microgravity Conditions

Two-phase flows of gas and liquid are increasingly paid much attention to space application due to excellent properties of heat and mass transfer, so it is very meaningful to develop studies on them in microgravity. In this paper, gas-phase distribution and turbulence characteristics of bubbly flow in normal gravity and microgravity were investigated in detail by using Euler–Lagrange two-way model. The liquid-phase velocity field was solved by using direct numerical simulations (DNS) in Euler frame of reference, and the bubble motion was tracked by using Newtonian motion equations that took into account interphase interaction forces including drag force, shear lift force, wall lift force, virtual mass force and inertia force, etc. in Lagrange frame of reference. The coupling between gas–liquid phases was made with regarding interphase forces as a momentum source term in the momentum equation of the liquid phase. Under the normal gravity condition, a great number of bubbles accumulate near the walls under the influence of the shear lift force, and addition of bubbles reduces turbulence of the liquid phase. Different from the normal gravity condition, in microgravity, an overwhelming majority of bubbles migrate towards the centre of the channel driven by the pressure gradient force, and bubbles have little effect on the turbulence of the liquid phase.     

Detection of localized methylmercury contamination by use of the mussel adductor muscle in Minamata Bay and Kagoshima Bay, Japan

Based on our previous finding that the concentrations of total mercury in mussel adductor muscle approximated those of methylmercury, we compared concentrations of total mercury in the adductor muscle of the mussel Mytilus galloprovincialis, collected from four sites around Minamata City from 1993 to 1995 and four sites in Kagoshima Bay from 1997 to 1998, to assess the level of localized methylmercury contamination. Though the input of mercury from the chemical plant had stopped by around 1970, concentrations of total mercury in the mussel adductor muscle were higher at two sites (26-121 ng/g, n = 135) near the main fallout of wastewater from the chemical plant in Minamata Bay than at the other sites, i.e. two sites 1-5 km from the former sites in Minamata City (6-28 ng/g, n = 52), and all sites in Kagoshima Bay (2-30 ng/g, n = 287). The localized methylmercury contamination around the chemical plant in Minamata Bay was documented also by our sensitive analysis of mercury concentrations in seawater and sediment samples. The survey of concentrations of total mercury in the mussel adductor muscle seems to be useful for monitoring the methylmercury contamination in coastal areas.     

Thermoresponsive microhydrogels: preparation,properties and applications

A microgel is a fascinating type of soft matter. Among the various microgels, great interest has been shown in microhydrogels because their functions are realized in water, which is the most benign liquid to humans. The microhydrogel‐composing polymers have their own delicate hydrophilic ? hydrophobic balance, which is sensitive to environmental conditions such as temperature, pH, ionic strength, light and specific (bio)molecules, in many cases. This review describes the methodology for the preparation of such microhydrogels, their properties, and finally their applications in physicochemical, biological and biomedical, optical and photonic, and chemical fields. The main material cited is a representative temperature‐sensitive polymer, poly(N‐isopropyl acrylamide), but some other environment‐friendly polymers such as cellulose derivatives are also reported. © 2013 Society of Chemical Industry     

Hot water resistance of glass‐fiber and glass‐bead reinforced thermoplastics

The hot water resistance of three kinds of short glass fiber or glass bead‐reinforced plastics [polyphenyleneether (PPE), polyphenylenesulfide (PPS), and polyoxymethylene (POM)] was studied by hot water immersion testing, tensile testing and water‐hammer fatigue testing. It was found that the degradation of the strength was observed only for the reinforced plastics under hot water immersion and that the change of the tensile strength was most drastic in glass fiber‐reinforced PPS (GFPPS). Scanning electron microscope (SEM) observations of the tensile fracture surface revealed that the change in tensile strength was attributable to the deterioration of the interface between the glass fiber and the matrix resin. The results of acoustic emission analysis also supported the conclusion that the change in strength was due to the deterioration of the interface. Although the change in the tensile strength of glass fiber‐reinforced PPE (GFPPE) was small compared with that of GFPPS, debonding between the glass fiber and the matrix resin and surface cracks was observed on the surface of the GFPPE specimens.