Sonographic depiction of fetal tooth germs

Recently, sonography of the fetal face has gained increasing importance in prenatal diagnosis. It is not yet clear whether sonographic depiction of fetal tooth germs would have an influence on the prenatal diagnosis of ectodermal dysplasia syndromes. During routine malformation screening, horizontal sections of fetal jaws were visualized and examined for tooth germs in 124 pregnant women following sonographic ‘facing’. Histological jaw sections of fetuses that had died in utero at various gestational ages were produced in order to examine the degree of correspondence between the sonographic and histological findings. At least four tooth germs were found in the jaws of all fetuses between 19 and 34 gestational weeks (n=104). Although jaw visualization was possible between 14 and 18 gestational weeks (n=20), the exact number and location of the tooth germs could not be determined. Assessment of tooth germs may become increasingly important, as aplasia of the tooth germs is one of the principal signs of various hereditary ectodermal diseases.     

Changes in the central and peripheral circulatory system in response to the cold: own studies using impedance plethysmography and Doppler ultrasound

The aim of the study was to determine the cardiovascular response to continuous (4 °C for 60 min) and intermittent (10 min at 4?°C and 10 min at room temperature alternately) exposure to the cold in 30 healthy young men. The subjects were equipped with a set of identical clothing (insulation 2.1 clo) and during the stay in the chamber and outside performed the same activities, i.e., walking on a treadmill at a speed of 0.5?km/h. The tests included assessing the central circulatory system using the Holter system and assessing the peripheral circulatory system using impedance plethysmography and Doppler ultrasound. The analysis of the parameters that describe the central and peripheral circulation poses a difficulty in determining which variant of exposure constitutes a greater load on the circulatory system. It should be noted that even the conditions used in the study may cause adverse effects in the cardiovascular system.     

捕尘过滤材料清洗再生实验研究

空气颗粒物过滤材料作为一次性使用的耗材,在阻力升高至一定值时就被更换并抛弃,不仅使过滤系统成本增加,而且会产生二次污染,不利于生态环保。通过实验探究滤料清洗再生的方法,研究了MES表面活性剂浓度、温度、清洗时间对清洗效果的影响。结果表明:温度为25℃、MES溶液质量分数为0.7%、清洗时间为30 min时的清洗效果最佳,清洁度可达97%,结合超声波辅助时可使清洁度增至99.2%,经过4次清洗再生后,滤料的阻力、效率与纤维力学性能未发生明显变化,证明了该方法在工业应用中的可能性。     

The effect of fetal gender on nuchal translucency at 10–14 weeks of gestation

Recent data have suggested that fetal nuchal translucency (NT) is affected by fetal gender. We investigated the size of this effect in 12 189 unselected pregnancies with known normal outcomes that had undergone NT measurements between 10 and 14 weeks of gestation. NT increased with gestation and was converted to multiples of the median (MoM) for the gestational day. The median NT MoM (95% CI) for female fetuses was 0.98 (0.97–0.99). This was significantly lower than that of the male fetuses (1.03; range1.02–1.04) (p<0.0005; Wilcoxon rank-sum test). The gender difference was not observed at 10 weeks but was observed from 11 weeks onwards. There is no obvious explanation for the above findings. Copyright © 2001 John Wiley & Sons, Ltd.     

Fused CFD-interpolation model for real-time prediction of hazardous gas dispersion in emergency rescue

Accidental releases of hazardous gases in chemical industries can pose great threats to public security. The computational fluid dynamics (CFD) model is commonly applied to predict gas dispersion in complex structured areas. It can provide good accuracy but it is too time-consuming to be used in emergency response. To reduce computation time while keep acceptable accuracy, this paper proposes several fused CFD-interpolation models which combine CFD model with different interpolation methods. Spline, linear and nearest interpolation methods are used. A CFD simulations database is created ahead of time which can be quickly recalled for emergency usage and unknown situations can be predicted instantly by interpolation methods instead of time-consuming CFD model. Fused models were applied to a case study involving a hypothetical propane release with varying conditions and validated against CFD model. The validation shows that prediction accuracy of these fusion models is acceptable. Among these models, CFD-Spline interpolation model performs best. It is faster than CFD model by a factor of 75 and is potentially a good method to be applied to real-time prediction.     

超声协同下镍铁双金属化合物催化降解水溶液中的四氯化碳

以水合肼作为还原剂、PVP作为稳定剂,在碱性条件下借助水热途径制备了FeNi3双金属化合物,并对其物相结构与外观形貌进行了表征。在超声协同作用下用自制的FeNi3化合物微粉作为催化剂对水溶液中的四氯化碳进行了催化降解处理,考查了超声功率、催化剂加入量、温度和pH值对四氯化碳降解效果的影响,同时,与超声辅助还原铁粉降解四氯化碳进行了比较。结果表明,FeNi3化合物对于水溶液中的四氯化碳具有显著的催化降解作用,催化剂投加量增大,四氯化碳的降解率升高。在给定的实验条件下,温度对四氯化碳降解效果的影响最为显著,40℃时,15 min内四氯化碳的降解率即可达到94.61%,而且其降解效果明显优于还原铁粉(68.34%)。     

超声联合碱解预处理对剩余污泥破解和厌氧消化的影响

对比研究了单独超声、单独碱解和两者联合预处理对污泥破解和厌氧消化性能的影响。以加碱量和输入能量为控制参数,研究了不同条件下的污泥破解和有机物溶解变化。结果表明：联合预处理技术对污泥破解和有机质溶解的效果比超声和碱解单独作用之和更好。污泥破解增加值ΔSCOD/TCOD和加碱量之间存在显著的线性关系（R2=0.936）。超声和碱解联合预处理对污泥厌氧消化产甲烷量较原泥增加了16.57%~31.13%。厌氧消化产甲烷结果表明,SCOD/TCOD的增加并不总是促进厌氧消化性能的改善,二者之间存在二次非线性关系（R2=0.85）,且厌氧消化性能最高点出现在超声能量12 000 kJ·kg-1（TS）、加碱量0.08 g·g-1（TS）联合作用条件下。