Airway resistance and work of breathing in tracheostomy tubes

Recommendations for sizing of tracheostomy tubes are generally based on anatomic considerations with the largest fitting tube most commonly placed. Once in the tracheostomy site, the tube assumes the new role of the upper airway. Consideration of the airway resistance of each tracheostomy tube and change in work of breathing are important in maintaining the respiratory system homeostasis. The airflow dynamics of neonatal, pediatric, and adult tracheostomy tubes were studied. Flow rates were plotted against change in pressure for inspiratory and expiratory flows and resistances for each tube were calculated. The expiratory resistances were larger for the neonatal tubes and pediatric tubes 0 and 00, while inspiratory resistances were the limiting factor in the adult tubes and the larger pediatric tubes. Comparison of calculated resistances of the tracheostomy tubes was made with known physiologic airway resistances. Adult tubes 8 and 10 most closely simulated the upper airway resistance of adults and neonatal tube 0 appeared most appropriate for the newborn. Work of breathing was determined for each tracheostomy tube. Increasing tube diameter as well as decreasing tidal volume and respiratory rate decreased the amount of work required to maintain a given flow.     

Kinetics of aspartame precursor synthesis catalysed by Pseudomonas aeruginosa elastase

Elastase isolated from Pseudomonas aeruginosa IFO 3455 was found to be an efficient protease to catalyse the synthesis of N-benzyloxycarbonyl-aspartyl-phenylalanine methyl ester, the precursor of the dipeptide sweetener, aspartame. The influence of methanol as a cosolvent in this synthetic reaction was investigated. It was found that the synthesis of the dipeptide precursor was most efficient in 25% (v/v) methanol, pH 7·0 at about 25°C for a reaction time of about 3 h. However, the activity of the enzyme was greatly reduced in 90% methanol. The values of K and k₂ for N-benzyloxycarbonyl-aspartic acid were 0·17 mol dm^?3 and 11·9 mol dm^?3 s^?1 respectively.     

Effects of controlled texturization of the crystalline Si surfaceon the SiO2/Si effective barrier height

A two-stage plasma etch texturination process to control the level of crystalline silicon surface roughness has been investigated. Initially, a Cl₂ plasma etch is used to produce a very rough Si surface. This is followed by an isotropic SF₆ plasma etch, whose etch time is used to reduce and control the level of surface roughness created by the previous step. Oxides grown on texturized Si surfaces with short SF₆ etch times exhibit lower effective SiO₂/Si barrier height and greater electron injection enhancement than those with longer SF₆ etch times     

Vancomycin administration in continuous ambulatory peritoneal dialysis: the risk of ototoxicity

Patients diagnosed with nodules (NO = 40) in a large university hospital clinic and an age-stratum matched nondiseased group (ND = 200) described adverse outcomes of vocal impairment on work and work-related communications. NOs were significantly more likely than NDs to report symptoms of hoarseness (73% vs. 26%), high-note difficulty (70% vs. 20%), difficulty speaking with a lower voice (53% vs. 13%) and a tired voice (50% vs. 10%), and their greatest source of physical discomfort was associated with scratchiness (61% vs. 3%). The average number of symptoms was four in NOs and less than one in NDs. Nodule patients were most concerned about the effects their voice problem would have on their future career (78% vs. 24%) and 49% of NOS reported their voice problem had an adverse work effect in the past compared with 4% of NDs. Having a voice condition limited current job performance in 39% of the NO group but only in 2% of the ND group. The results suggest that a diagnosis of nodules plays a major role in disrupting careers and work activities and that available educational programs and additional research are needed for improving their functional ability and preventing adverse outcomes in the lives of individuals with voice disorders.     

细纱机采用水冷电机的节能性分析

探讨细纱机采用水冷电机的节能性。通过分析细纱机传统风冷式电机散热工作特点,分析了水冷电机的工作原理及特点,并用实例对水冷电机的节能性进行了分析。在纺织厂细纱车间的实际工程应用表明:设备采用水冷电机与风冷电机相比,水冷电机具有效率高、可有效降低空调冷负荷和车间温度、简化空调系统、节约能源、减少车间温度不均等优点。     

Synthesis and identification of artificial antigens for cadmium and copper

Cadmium and copper were conjugated to two carrier proteins using bifunctional chelators, including derivatives of ethylenediamine N,N,N′,N′-tetraacetic acid and 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid, to make artificial antigens for cadmium and copper. The artificial antigens were identified by nondenaturing gel electrophoresis, ultraviolet spectrophotometry, and graphite furnace atomic absorption spectrometry. Nondenaturing gel electrophoresis results revealed that the conjugate band migrations were different from those of the chelator-protein conjugates and carrier proteins alone. The ultraviolet spectrophotometry results revealed that the maximum absorption peak of the conjugates had only a little peak shift. The graphite furnace atomic absorption spectrometry results revealed that the metal content of the conjugates was much higher than that of the carrier proteins and chelator-protein conjugates. The results indicated that the artificial antigens for cadmium and copper were successfully synthesised and could be useful as immunising antigens.     

减振镗杆动态特性的对比实验分析

对进口肯纳减振镗杆和自制减振镗杆进行对比切削实验,分析其抗颤振能力的差别。应用实验模态分析、镗杆材料化学成分对比分析等手段,对两种镗杆的动态特性进行分析,为自制减振镗杆的优化设计提供依据。     

基于CPLD的三维加速度存储测试方法研究

提出一种基于CPLD的三维加速度存储测试方法。硬件测试模块以EPM240T100C3为核心,详细介绍了其系统组成、电路设计原理,并根据测试对象的特殊性,从性能与体积上对整个测试系统进行了优化;软件设计模块控制程序使用VHDL语言编写,描述了其设计思想,并通过软件仿真进行了验证,给出了时序仿真图;数据通信模块,利用CPLD内部丰富的逻辑单元实现UART功能,通过RS232串口与上位机通信。结果证明所设计的存储测试系统能够满足高速采样与存储的要求,可以用于实际的弹载三维加速度测试。     

基于自适应加权融合的标准铜柱鉴选研究

介绍了标准铜柱在塑性测压校准系统的重要作用及其鉴选方法。为提高测压铜柱受压后变形量测量准确性,提出了用自适应加权融合算法应用于变形量的融合计算,利用所提供的数据融合出标准偏差最小的数据融合值,以3.5×8.75、4×6.5、8×13测压铜柱实测数据为例,比较分析了各型号铜柱采用自适应加权融合算法与平均估算法、贝赛尔公式计算法的有效性和融合精度的差异,从理论和实践两个方面验证了该方法的有效性,提高了融合精度。     

基于单片机的温度存储测试技术研究

爆炸温度场具有温度高、面积大、变化快的特点,伴有高压及高速气流,常规的有线式温度测试方法存在测试电缆易损坏、误触发等问题。基于此,设计了一种爆炸温度场存储式测温系统。该系统由上位机及下位机系统组成,下位机系统主要由钨铼热电偶、信号调理模块、C8051F020单片机、存储模块、通讯接口等硬件组成,并利用C语言设计了测试系统的下位机程序,采用LABVIEW编制了上位机处理软件。分别从方案设计、硬件实现、软件实现等方面进行了研究和描述,并给出了测试系统的典型应用。实验结果表明,该系统稳定可靠,能够准确有效地进行温度信号采集,并获取相应的实验参数。