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61.
We report the generation of action potentials in crayfish neurons by magnetic pulses for analytical purposes. A copper wire toroid, containing a ferrite core, was placed around the nerve bundle, and square wave current pulses were sent through the wire to generate a magnetic field. The magnetic field generated an action potential in the neuron that was detected downfield by a pickup microelectrode. The biosensor was used to detect local anesthetics by monitoring the time necessary for complete blockage of the action potential. Techniques for improving the efficiency and lifetimes of neural biosensors are discussed. 相似文献
62.
TR DeGrado TG Turkington JJ Williams CW Stearns JM Hoffman RE Coleman 《Canadian Metallurgical Quarterly》1994,35(8):1398-1406
METHODS: This study characterizes the performance of a newly developed whole-body PET scanner (Advance, General Electric Medical Systems, Milwaukee, WI). The scanner consists of 12,096 bismuth germinate crystals (4.0 mm transaxial by 8.1 mm axial by 30 mm radial) in 18 rings, giving 35 two-dimensional image planes through an axial field of view of 15.2 cm. The rings are separated by retractable tungsten septa. Intrinsic spatial resolution, scatter fraction, sensitivity, high count rate performance and image quality are evaluated. RESULTS: Transaxial resolution (in FWHM) is 3.8 mm at the center and increases to 5.0 mm tangential and 7.3 mm radial at R = 20 cm. Average axial resolution decreases from 4.0 mm FWHM at the center to 6.6 mm at R = 20 cm. Scatter fraction is 9.4% and 10.2% for direct and cross slices, respectively. With septa out, the average scatter fraction is 34%. Total system sensitivity for true events (in kcps/(microCi/cc)) is 223 with septa in and 1200 with septa out. Dead-time losses of 50% correspond to a radioactivity concentration of 4.9 (0.81) microCi/cc and a true event count rate of 489 (480) kcps with septa in (out). Noise-equivalent count rate (NECR) for the system as a whole shows a maximum of 261 (159) kcps at a radioactivity concentration of 4.1 (0.65) microCi/cc with septa in (out). NECR is insensitive to changes in lower gamma-energy discrimination between 250-350 keV. CONCLUSIONS: The results show the performance of the newly designed PET scanner to be well suited for clinical and research applications. 相似文献
63.
BACKGROUND: Hepatocellular carcinoma (HCC) over 10 cm in diameter at the time of diagnosis continues to account for a number of patients undergoing hepatic resection. This study evaluated the clinicopathological features and outcome following surgery for large HCC. METHODS: Forty patients with a large HCC (greater than 10 cm) (group 1) resected between 1991 and 1996 were studied retrospectively. They were compared with 245 patients who had smaller HCCs (10 cm or less) (group 2). RESULTS: No patient in group 1 had hepatitis C infection compared with 22.9 per cent in group 2 (P=0.001). Patients in group 1 were significantly younger, had higher alpha-fetoprotein levels (16750 versus 1864 ng/ml; P < 0.001), better liver function, a higher incidence of multiple tumours (27 of 40 versus 42.0 per cent; P=0.003) and venous invasion (35 of 40 versus 52.2 per cent; P < 0.001), and underwent more major resections (37 of 40 versus 26.5 per cent; P < 0.001) than those in group 2. Morbidity and mortality rates and hospital stay were comparable in the two groups. For group 1, the 1-, 3- and 5-year disease-free survival rates were 42, 30 and 28 per cent respectively. Multiple tumours, venous invasion and impaired liver function were factors associated with recurrence. CONCLUSION: Large HCC had specific clinicopathological features. In selected patients, resection is safe and offers the chance of long-term disease-free survival. 相似文献
64.
CW van Haselen PV Diederen J Toonstra SC van der Putte LH Rademakers JA Faber WA van Vloten 《Canadian Metallurgical Quarterly》1998,290(11):583-590
Small-cell variants of Sézary syndrome and mycosis fungoides (MF) have been described. However, in these studies the nuclear area of the small-cell variant of MF (SC-MF) as compared to histological classical MF (CL-MF) was not characterized objectively by quantitative electron microscopy. In a 14-year follow-up period, of a total of 76 patch/plaque stage MF patients seen in the Department of Dermatology of the University Hospital Utrecht, 14 (18%) had an infiltrate composed of atypical lymphocytes characterized by a distinctly smaller cell diameter and smaller, hyperchromatic, deeply indented nuclei as compared to the usual cell type of MF. The aim of the investigation was to confirm this observation objectively using quantitative electron microscopy (morphometry) and to define SC-MF as compared to CL-MF. The study was performed on the 14 patients with SC-MF, and 10 patients with clinical and histological CL-MF and 4 patients with chronic eczema. Electron micrographs of sections obtained from each biopsy were analysed by computer to produce the following data: a nuclear contour index (NCI), the mean nuclear area (MNA), the mean nuclear area of the cells above the 75th percentile (P75NA) and the percentage of cells larger than 30 microm2. The values of MNA differed significantly between patients with SC-MF and those with CL-MF (17.6 vs 23.2 microm2; P = 0.02), as did the values of P75NA (20.7 vs 27.9 microm2; P = 0.01). The NCI of the SC-MF and CL-MF patients were similar. These results are consistent with our observations that SC-MF does indeed exist. 相似文献
65.
The Toyota Production System (TPS) can result in huge benefits for companies and has been widely implemented around the world. Nevertheless, most adopters emphasize only the technical practices of the TPS, but neglect the critical role of human factors in the implementation of the TPS. Therefore, this study aims at developing an integrated TPS model that fully integrates the technical elements and human elements of the TPS with Total Quality Management (TQM) practices. An empirical study was conducted to confirm the causal relationships among these constructs. In the empirical study, questionnaires were mailed and e‐mailed to 620 companies that had implemented the TPS, and 151 of the completed questionnaires were valid. These 151 respondents were divided into eight categories. The results revealed that the implementation level of each construct was significantly different in each industry. The automobile and motorcycle industries have put a great deal of effort into the application of Humanity, Human Resource Management (HRM), and TQM practices and obtained good results. Other industries, however, ignored the implementation of HRM practices. The results also revealed that the early adopters enjoyed significant benefits from the implementation of the TPS, which led high‐tech companies to start adopting TPS practices and become lean enterprises. © 2011 Wiley Periodicals, Inc. 相似文献
66.
Palm-oil-in-water emulsions were prepared with mixtures of Tween 40 and Span 40 in various proportions. Stability and droplet-size
distribution of the emulsions were monitored. Interfacial tensions of the palm oil/water interface were also determined in
the presence of these emulsifier mixtures. Emulsifying efficiency of the emulsifier mixtures was assessed. No synergistic
effect of Tween 40 (sorbitan monopalmitate with 18–22 moles of ethylene oxide) and Span 40 (sorbitan monopalmitate) was found
on interfacial tension. Tween 40 alone (hydrophilic-lipophilic balance value 15.6) at 1.0% w/w gave palm oil emulsions that
were stable for more than 30 d at 60°C. Emulsifier mixtures of Tween 40 and Span 40 with hydrophilic-lipophilic balance values
in the range of 8.0–8.6 produced stable emulsions only at much higher emulsifier-mixture concentrations. The inherent nature
of the oil and the accompanying natural surface-active materials present in the oil can influence the prevailing conditions
at the oil/water interface and alter composition of the interfacial film and hence its stability. 相似文献
67.
Fluor公司开发的Fluor SOx净化工艺具有广泛多样的工艺布局,可以通过经济的方式定制脱除烟气中的有害组成。该工艺几乎能去除全部SOx并减少CO排放。Fluor SOx净化工艺的主要步骤已在多套工业装置中得到成功的证实。除技术可行、经济合理之外,Fluor SOx净化工艺不会产生任何有害副产物,也不会遇到与SOx有关的腐蚀问题。此外,该工艺生产高纯度可市售的元素硫。论述了Fluor SOx净化工艺的特征、技术和成本优势、设计和操作的简易性以及实施的便利性。 相似文献
68.
Fluor公司开发的Fluor SO_2净化工艺具有广泛多样的工艺布局,可以通过经济的方式定制脱除烟气中的有害组成。该工艺几乎能去除全部SO_2并减少CO排放。Fluor SO_x净化工艺的主要步骤已在多套工业装置中得到成功的证实。除技术可行、经济合理之外,Fluor SO_x净化工艺不会产生任何有害副产物,也不会遇到与SO_3 有关的腐蚀问题。此外,该工艺生产高纯度可市售的元素硫。论述了Fluor SO_x净化工艺的特征、技术和成本优势、设计和操作的简易性以及实施的便利性。 相似文献
69.
The business value of information technology (IT) has been one of the top concerns of both practitioners and scholars for decades. Numerous studies have documented the positive effects of IT capability on organizational performance but our knowledge of the processes through which such gains are achieved remains limited due to a lack of focus on the business environment. Such a linkage therefore remains the subject of debate in the information systems literature. In this study, we fill this gap by investigating the mediating role of business process agility and the moderating roles of environmental factors. On the basis of matched survey data obtained from 214 IT and business executives from manufacturing firms in China, our analyses show that even though firm-wide IT capability presents the characteristics of rarity, appropriability, non-reproducibility, and non-substitutability, its impact on organizational performance is fully mediated by business process agility. Our results also show that the impact of the environment is multifaceted and nuanced. In particular, environmental hostility weakens the effect of IT capability on business process agility, while environmental complexity strengthens it. The theoretical and practical implications of this study, and its limitations, are also discussed. 相似文献
70.
Initial cholesterol uptake by everted sacs of rat small intestine: Kinetic and thermodynamic aspects
The kinetics of initial cholesterol uptake by everted rat proximal and distal small intestinal sacs were evaluated in vitro.
The mucosal incubation solution consisted of 0.05 mM cholesterol solubilized in 4.8 mM sodium taurocholate micellar solution
at pH 7.4. Experiments were performed at temperatures from 26 to 38 C. The rate of cholesterol uptake followed a linear relationship
when plotted against time indicating an apparent zero-order kinetics mechanism for initial uptake. An Arrhenius plot of the
results of uptake versus temperature remained linear over the entire range of temperatures studied. The large free energy
of activation (20 kcal/mole) suggests that an energy barrier for cholesterol uptake exists at the enterocyte luminal cell
membrane and may be an important limiting step in cholesterol uptake. It is proposed that a transient association between
cholesterol and a component of the enterocyte luminal cell membrane is formed during initial uptake of cholesterol. The transient
association may be an activated complex formed with proteins present at or within the luminal enterocyte cell membrane. 相似文献