BackgroundSurgical-site infections due to intraoperative contamination are chiefly ascribable to airborne particles carrying microorganisms. The purpose of this study is to identify the actions that increase the number of airborne particles in the operating room.MethodsTwo surgeons and two surgical nurses performed three patterns of physical movements to mimic intraoperative actions, such as preparing the instrument table, gowning and donning/doffing gloves, and preparing for total knee arthroplasty. The generation and behavior of airborne particles were filmed using a fine particle visualization system, and the number of airborne particles in 2.83 m3 of air was counted using a laser particle counter. Each action was repeated five times, and the particle measurements were evaluated through one-way analysis of variance multiple comparison tests followed by Tukey–Kramer and Bonferroni–Dunn multiple comparison tests for post hoc analysis. Statistical significance was defined as a P value ≤ .01.ResultsA large number of airborne particles were observed while unfolding the surgical gown, removing gloves, and putting the arms through the sleeves of the gown. Although numerous airborne particles were observed while applying the stockinet and putting on large drapes for preparation of total knee arthroplasty, fewer particles (0.3–2.0 μm in size) were detected at the level of the operating table under laminar airflow compared to actions performed in a non-ventilated preoperative room (P < .01).ConclusionsThe results of this study suggest that surgical staff should avoid unnecessary actions that produce a large number of airborne particles near a sterile area and that laminar airflow has the potential to reduce the incidence of bacterial contamination.

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URL:http://pec.eee.nagasaki-u.ac.jp/iidex-eng.hhd Absfmd -Resent developments of power electronics technology, low-loss iron core materials and highly efficient permanent maguet, etc have made it possible to realize a small size, high or ultra-high speed, end high performance electrical drive system. Such drive is expected for various kinds of applications such as ea-generation system, electrical vehicle and compressor, in which small size, tight weight and high efficiency are required.For these applications, we designed and built a trial ultra-high speed drive system of 2 poles, SkW, 240,000rpm. In this paper we describe our prototype system and show some experimental results. And the computer simulation was used to evaluate the fundamental motor characteristics at the fist of design stage and total systematic approach to enhance the total drive system. I. INTRDUCTIONResent developments of power electronics technology, low-loss iron core materials and highly efficient permanent magnet, etc have made it possible to realize a small size, high or ultra-high speed, high performance electrical drive system. Such drive is expected for various kinds of applications such as co-generation system, electrical vehicle and compressor, in which small size, light weight and high efficiency are required [l] [2].A directly coupled high speed motor is used to start up a gas turbine in the starting process of the co-generation system. After the gas turbine is ignited and becomes the source of mechanical power, the direct coupled motor operates as a generator. A high speed compressor is inevitable to improve efficiency of fuel cell system especially in electrical vehicle applications. In combination with a radial turhine and a compact heat exchanger, a high speed centrifugal compressor can be applied for small size and high efficient air cooling system. The small and highly efficient high speed drive system is also one of effective means to solve global environment problems in natural energy resources.For these applications, we designed and built a trial ultra-high speed drive system [3]. In this paper we describe our prototype system and show some experimental results. And entire this system was represented into the simulation model which is consist of digital DSP controller, analog inverter-converter circuits and motor. It is able tn calculate the all system phenomena through modeling of motor characteristics and circuit simulation. Methodologies for extracting the parameters of motor components are calculated FEM analysis. This exported equivalent circuit model was taken into account of the entire system simulation model.