Magnetic resonance findings in skeletal muscle tears

Magnetic resonance (MR) images of skeletal muscle tears can clearly delineate the severity of muscle injury. Although MR imaging is seldom necessary in patients with acute muscle trauma, it can be helpful in deciding on clinical management. The two major MR findings in acute muscle tears are deformity of the muscle and the presence of abnormal signal reflecting hemorrhage and edema. In acute tears, methemoglobin within the extravascular blood causes high-signal areas on both T1- and T2-weighted images. With partial tears, the blood may dissect in a distinctive linear pattern along the muscle bundles and fibers. As healing begins, the muscle signal diminishes, first on the T1-weighted images and then on the T2-weighted images. When there is residual abnormal signal on images obtained more than several months after the injury, it is presumed to represent hemorrhage from recurrent tears. In patients with a questionable history of a remote injury, the clinical presentation may be that of persistent pain or a soft tissue mass. In these cases MR imaging may identify the cause of the pain and can exclude a neoplasm by proving that the mass is a hypertrophied or retracted muscle. Thus, MR imaging has a limited, but occasionally important role in selected patients with skeletal muscle tears.     

Electronic gate detection for cell or particle counting and sizing in liquids: front-end characteristics, flow-dependent gate impedance, and its remediation

The detection sensitivity and the sizing resolution of electronic gating are inherently limited by fluctuating gate impedance and flow-induced noise. Instabilities of this type, as shown, are due to varying flow patterns of the carrier liquid beyond the gate. Their effects, although largely hidden in dc-operated gating, cause broadening and shift of cell/particle-size distributions under measurement. RF-operated gating, more specifically the demodulation operation, is much more hindered. For an investigation of these effects, a physical model is proposed along with a procedure for the identification of the system parameters. A detector of dedicated concept is used for evaluating the model, and, more specifically, for investigating the impact of configurational and hydrodynamic parameters. Experiments prove that the origin of flow-dependent gate impedance is to be located inside a zone of only a few-micrometer extent at the gate outlet. This is confirmed by the calculated electric field patterns. On such grounds, electrode configurations are proposed that minimize the current density in the zone of hydrodynamic instability and, hence, the flow-induced noise. The same configurations also minimize the impedance of the gate as signal source, facilitating broadband operation, and multifrequency cell impedance measurements.     

Simulation of runoff and phosphorus transport in a Carpathian catchment,Slovakia

A comprehensive, GIS‐based modelling approach is developed to estimate runoff and phosphorus transport within a watershed at a daily time step. The approach relies on the use of GIS data for deriving major critical model parameters that exhibit distinct spatial variability over the catchment. Surface runoff is calculated by a modified rational method, which depends upon rainfall intensity, soil moisture status, slope, land‐use and soil characteristics. Phosphorus loading is estimated as a function of the runoff volume and the event mean concentration for different land use categories. A diffusive approximation method is used to trace runoff and phosphorus transport to the basin outlet. The modelling approach is tested in the Margecany catchment, Hornad River basin, Slovakia, to simulate runoff, phosphorus loading, and its transport on a daily time scale using data observed between 1995 and 2000. Satisfactory results of the hydrographs and phosphorus concentration at the basin outlet are obtained, though more efforts regarding the phosphorus cycling and its biochemical reactions need to be clarified by further research. Copyright © 2006 John Wiley & Sons, Ltd.     

三元催化转化器中的现象分析与研究

在介绍和分析国内外研究现状的基础上，论述了三元催化转化器中的传递现象及化学反应动力学．探讨了三元催化转化器在暖机过程中有害物质的催化转化模型，并建议采用数学模型的方法对催化器在发动机所有工况下的工作过程进行模拟。     

4-氨基-3-肼基-5-巯基-1,2,4-三唑的合成及其对醛的检验

以硫脲和水合肼合成了可用于检验醛的试剂——4-氨基-3-肼基-5-巯基-1，2，4-三唑(别名：紫醛)，其结构通过红外光谱、核磁进行了确定。试验表明，紫醛对醛的检验敏感、专一、快速、操作简单。     

Study on the Intelligent System of Gear Pitch Deviation Measurement and Analysis

The intelligent controlling and data process of pitch error measurement is proposed. The whole system takes C++ as the development tool and takes advantages of object-oriented and visualization, having the advantages of easy operation and humanistic interface. In the meanwhile, the system can be complemented and improved according to the demand of user, having certain independence. The research of the system provides an efficient and reliable way to measure and analyze the gear pitch, which can be referenced in the future research.     

Use of postconsumer polyethylene in blends with polyamide 6: Effects of the extrusion method and the compatibilizer

Blends of polyamide and high‐density polyethylene show adequate properties for a large range of applications: they are used for the production of filaments, containers, and molding resins. The effect of the addition of 2 wt % of a compatibilizer, maleic anhydride grafted polyethylene, to the blend was studied and compared to the use of postconsumer polyethylene. The samples were extruded with single‐ and twin‐screw extruders with 25, 50, or 75 wt % f polyethylene, and the test specimens, molded by injection, were characterized by stress–strain tests, thermal properties, and morphologies. Processing the blends with postconsumer polyethylene in both extruders improved the mechanical properties in comparison to the blends processed with high‐density polyethylene and the compatibilizer. The morphologies of these blends showed that there was a decrease in the domain size of the disperse phase with the use of the compatibilizer or postconsumer polyethylene. The results indicate that for this blend, postconsumer polyethylene substituted, with advantages, for the necessity of a compatibilizer and the use of the high‐density polyethylene. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008.     

Comparative Study of Models on Confinement of Concrete Cylinders with Fiber-Reinforced Polymer Composites

The use of fiber-reinforced polymer (FRP) composites for strengthening and/or rehabilitation of concrete structures is gaining increasing popularity in the civil engineering community. One of the most attractive applications of FRP materials is their use as confining devices for concrete columns, which may result in remarkable increases of strength and ductility as indicated by numerous published experimental results. Despite a large research effort, a proper analytical tool to predict the behavior of FRP-confined concrete has not yet been established. Most of the available models are empirical in nature and have been calibrated against their own sets of experimental data. On the other hand, the experimental results available in the literature encompass a wide range of values of the significant variables. The objective of this work is a systematic assessment of the performance of the existing models on confinement of concrete columns with FRP materials. The study is conducted in the following steps: the experimental data on confinement of concrete cylinders with FRP available in the technical literature are classified according to the values of the significant variables; the existing empirical and analytical models are reviewed, pointing out their distinct features; the whole set of available experimental results is compared with the whole set of analytical models; and strengths and weaknesses of the various models are analyzed. Finally, a new equation is proposed to evaluate the axial strain at peak stress of FRP-confined concrete cylinders.