Current status of prenatal diagnosis,operative management and outcome of esophageal atresia/tracheo-esophageal fistula

Ultrasonographic features suggestive of esophageal atresia with or without tracheo-esophageal fistula (EA/TEF) are only in a small minority of fetuses with EA/TEF (<10%) identifiable on prenatal scans. The prenatal diagnosis of EA/TEF relies in principle, on two nonspecific signs: polyhydramnios and absent or small stomach bubble. Polyhydramnios is associated with a wide range of fetal abnormalities, but most commonly it pursues a benign course. Similarly the sonographic absence of a stomach bubble may point to a variety of fetal anomalies. The combination of polyhydramnios and absent stomach bubble in two small series offers a modest positive predictive value of 44 and 56% respectively. Prenatal scanning for EA/TEF identifies a larger proportion of fetuses with Edwards syndrome; there is also a higher proportion of isolated EA in comparison to postnatal studies. Current ultrasound technology does not allow for a definite diagnosis of EA/TEF and therefore, counseling of parents should be guarded. Postnatal diagnosis of EA is confirmed by the failure to pass a firm nasogastric tube into the stomach; on chest X-ray, the tube is seen curling in the upper esophageal pouch. Corrective surgery for EA/TEF is well established and survival rates of over 90% can be expected. Copyright © 2008 John Wiley & Sons, Ltd.     

Retrieval of refractive index of ultrafine single particle using hygroscopic growth factor obtained by high sensitive surface plasmon resonance microscopy

When exposed to different relative humidities (RHs), the optical properties of atmospheric aerosols will change because of changes in the aerosol particle size and complex refractive index (RI), which will affect haze formation and global climate change. The potential contributions of ultrafine particles to the atmospheric optical characteristics and to haze spreading cannot be ignored because of their high particle number concentrations and strong diffusibility; measurement of the optical properties of wet ultrafine particles is thus highly important for environmental assessment. Therefore, a surface plasmon resonance microscopy with azimuthal rotation illumination (SPRM-ARI) system is designed to determine the RIs of single particle aerosols with diameters of less than 100 nm in the hygroscopic growth process. Measurements are taken using mixed single particles with different mass ratios. The RIs of mixed single aerosols at different RHs are retrieved by measuring the scattering light intensity using the SPRM-ARI system and almost all the RIs of the bicomponent particles with different mass ratios decrease with increasing water content under high RH conditions. Finally, for each of the bicomponent particles, the maximum standard deviations for the retrieved RI values are only $2.06\times {10}^{-3}$, $3.08\times {10}^{-3}$ and $3.83\times {10}^{-3}$, corresponding to the NaCl and NaNO₃ bicomponent particles with a 3:1 mass ratio at 76.0% RH, the NaCl and glucose particles with a 1:3 mass ratio at 89.0% RH, and the NaCl and OA particles with a 1:1 mass ratio at 78.0% RH, respectively; these results indicate that the high-sensitivity SPRM-ARI system can measure the RI effectively and accurately.     

环境烟草烟气粒径分布及其对光散射的影响

为了测量典型办公室内环境中环境烟草烟气悬浮颗粒物的数浓度和粒径分布变化,以及其对颗粒光散射的影响,在6.8 m×3.2mx2.8 m的试验间进行试验,采用测量范围为5～1 000 nm的DMS500扫描电迁移率粒径谱仪进行粒径测量.结果表明,不同卷烟样品的烟气粒径分布曲线近似,都可以用对数正态分布函数来描述.4种卷烟样品粒径分布及参数变化速率相似,在4 800 s内数中值粒径CMD平均值从105 nm增大至155 nm,几何标准差GSD平均值从1,58减小至1.45,CMD和GSD的变化趋势近似符合指数函数.利用基于Mueller光散射理论的程序计算烟颗粒对散射光的影响.粒径分布的变化显著改变了颗粒散射光强度,CMD最大使散射光强度增大7倍,GSD引起的强度变化较小.综合考虑烟气颗粒数浓度降低和粒径分布的变化,散射光强度最大增大3倍.     

Dynamic behaviour of direct spring loaded pressure relief valves in gas service: II reduced order modelling

A previous study of gas-service direct-spring pressure relief valves connected to a tank via a straight pipe is continued by deriving a reduced-order model for predicting oscillatory instabilities such as valve flutter and chatter. The reduction process uses collocation to take into account a finite number N of acoustic pressure waves within the pipe, resulting in a set of 2N+3 ordinary differential equations. Following a novel non-dimensionalization, it is shown analytically that the model can exhibit, at experimentally realistic parameter values, instabilities associated with coupling between the valve and acoustic waves in the pipe. The thresholds for each instability are such that for a given flow rate, the first mode to go unstable as the inlet pipe length increases is the quarter-wave mode, then a three-quarter wave, a 5/4-wave etc. Thus the primary mode of instability should always be due to the quarter wave. In the limit of low flow rates, a simple approximate expression is found for the quarter-wave instability threshold in the form of inlet pipe length against mass flow rate. This threshold curve is found to agree well with simulation of the full model. For higher flow rates there is a need to include fluid convection, inlet pressure loss and pipe friction in order to get good agreement. The reduced model enables the dependence of the stability curve on key dimensionless physical parameters to be readily computed.     

绿灯倒计时信号对驾驶行为的影响

为揭示绿灯倒计时信号对交叉口交通安全的影响,针对不同交通负荷与信号控制方式下的驾驶行为开展研究。选择大连市内的倒计时信号交叉口与非倒计时信号交叉口各2处,开展车辆行驶速度及不良驾驶行为调查。用数理统计方法,对比分析2类交叉口在平峰与高峰时段的车辆行驶速度特性,同时对比分析上述不同条件下闯黄灯及违规变道行为的发生数量。研究表明,绿灯倒计时信号在绿灯时间末期,会诱发一部分驾驶员加速行驶通过交叉口;绿灯倒计时信号在平峰时段对闯黄灯行为数量的影响较小,而对违规变道行为的数量有显著影响。     

BiOCl/TiO_2复合材料的可见光活性及机理研究

采用水热法和溶胶凝胶法制备新型BiOCl/TiO2复合材料并明确了最优的掺杂比例(2%).随后利用X射线衍射(XRD)、紫外可见漫反射(DRS)、透射电镜(TEM)和X射线光电子能谱(XPS)对该材料进行表征.由于禁带宽度较大,纯BiOCl和TiO2的可见光催化性能极差,然而二者复合后,同条件下的苯降解率却大幅提升,可以达到40%以上.经证实,催化剂制备过程中,Bi的状态发生变化,在TiO2导、价带之间插入新的能级,使其禁带宽度变窄,电子可以实现可见光跃迁.     

Synthesis, crystal structure, photodegradation kinetics and photocatalytic activity of novel photocatalyst ZnBiYO4

ZnBiYO₄ was synthesized by a solid-state reaction method for the first time. The structural and photocatalytic properties of ZnBiYO₄ were characterized by X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy and UV-Vis diffuse reflectance. ZnBiYO₄ crystallized with a tetragonal spinel structure with space group I41/A. The lattice parameters for ZnBiYO₄ were a = b = 11.176479 Å and c= 10.014323 Å. The band gap of ZnBiYO₄ was estimated to be 1.58 eV. The photocatalytic activity of ZnBiYO₄ was assessed by photodegradation of methyl orange under visible light irradiation. The results showed that ZnBiYO₄ had higher catalytic activity compared with N-doped TiO₂ under the same experimental conditions using visible light irradiation. The photocatalytic degradation of methyl orange with ZnBiYO₄ or N-doped TiO₂ as catalyst followed first-order reaction kinetics, and the first-order rate constant was 0.01575 and 0.00416 min^-1 for ZnBiYO₄ and N-doped TiO₂, respectively. After visible light irradiation for 220 min with ZnBiYO₄ as catalyst, complete removal and mineralization of methyl orange were observed. The reduction of total organic carbon, formation of inorganic products, SO₄^2- and NO₃^-, and evolution of CO₂ revealed the continuous mineralization of methyl orange during the photocatalytic process. The intermediate products were identified using liquid chromatography- mass spectrometry. The ZnBiYO₄/(visible light) photocatalysis system was found to be suitable for textile industry wastewater treatment and could be used to solve other environmental chemical pollution problems.     

对核磁共振成像仪建设项目环境影响评价的研究

核磁共振作为一种分析手段广泛应用于物理、化学、生物、医疗等领域.本文从核磁共振原理出发,分析核磁共振成像仪主要环境影响,结合环评现状,分析环评管理存在的主要问题,结合相关法规条文,查找存在这些问题的主要原因,结合目前核磁共振仪的建设情况和使用条件,从切合实际角度出发,提出核磁共振成像仪建设项目环评管理建议.     

Ecotect在建筑玻璃幕墙光反射影响评价中的应用研究

将Ecotect软件应用到建筑玻璃幕墙光反射影响评价中,应用结果表明,Ecotect软件能准确地确定建筑玻璃幕墙反射光的影响范围,且能准确地确定幕墙遮阳设施或周围建筑的遮挡效果,这可大大加强建筑玻璃幕墙光反射影响评价的准确性.另外,Ecotect软件还可准确地分析出受影响的敏感目标或敏感目标受照反射光的来源,这可使幕墙设计者有针对性对受影响敏感目标或对敏感目标产生反射光影响的建筑玻璃幕墙立面采取预防控制措施,来降低或者消除光反射,从而从源头上减少或消除幕墙反射光对周围环境敏感目标的影响.     

蒙脱土原位生长MoS2复合材料光催化降解罗丹明B的机理研究

通过在Na⁺-MMT表面生长MoS₂来提高窄带隙半导体光生电子分离速率及稳定性.利用阳离子填充法及水热法成功制备了复合光催化剂Na⁺-MMT/MoS₂,并通过FT-IR、SEM、TEM、Raman、XRD、TG、XPS、UV-DRS和ESR等表征进一步证明了材料的成功负载及光、电化学性能. 同时,以有机染料罗丹明B为待降解染料来评价光催化剂的催化性能,发现其在80 min可有效降解罗丹明B,降解率达96%.经过5次循环使用后,Na⁺-MMT/MoS₂复合光催化剂仍具有较好的光催化性能.因此,利用MMT的表面电负性及稳定的片层结构负载MoS₂,可形成光生电子迁移通道进一步提高电荷迁移速率及光催化剂的稳定性.本研究可为黏土材料调控窄带隙半导体制备环境友好型光催化剂提供新思路.