The mechanism of rapid, shallow breathing after inhaling histamine aerosol in exercising dogs

In 4 unsedated, exercising dogs, we studied the effects of inhaled histamine aerosol on minute volume of ventilation, respiratory frequency, tidal volume, total pulmonary resistance, and dynamic pulmonary compliance. Inhalation (5 breaths) of 1 to 2 per cent histamine aerosols increased minute ventilation (mean, 50 per cent; p less than 0.001) by increasing respiratory frequency (mean, 166 percent; P less than 0.001), despite decreasing tidal volume (mean, 42 percent; P less than 0.0001). Total pulmonary resistance increased (mean, 200 per cent; P less than 0.001.) Breathing supplemental O2 did not affect the ventilatory response to histamine. Adding external resistive loads to a dog's airway did not simulate the pattern of rapid, shallow breathing produced by histamine. Inhalation of terbutaline prevented the changes in total pulmonary resistance and dynamic pulmonary compliance but did not alter the ventilatory response to histamine. When conduction in the cervical vagus nerves (which were implanted chronically in skin loops) was blocked by cooling, the ventilatory response to histamine was abolished. We concluded that histamine stimulates breathing by stimulation of receptors whose afferent pathways are in the vagus nerves; the effective stimulus is not bronchoconstriction but is presumably due to direct stimulation of airway receptors.     

Hypertension detected in young black women by routine screening in a family planning clinics

The prevalence of hypertension, defined as a diastolic blood pressure over 100 mmHg, among young Black women who attended a family planning clinic in Johannesburg, was 2,85%, while in those over 35 years of age it was 8,5%. There was no correlation between hypertension and urbanisation, occupation or urinary sodium output. Within 6 months of diagnoisis, 84% of the women with hypertension had defaulted from the treatment clinic. Family planning clinics can economically screen patients for hypertension, but in this community a separate screening programme would not succeed until patient compliance has improved.     

Microstructuring ceramic scaffolds for hepatocyte cell culture

Both extracorporeal liver support devices and tissue engineering of liver for transplantation require the maintenance of functionality of liver cells (hepatocytes) in cell culture for a long time. One approach to achieve this is to optimize hepatocyte in vitro environment by using a scaffold with topographic structure at sub-millimeter scale which controls cell distribution. Therefore, a set of new type of titania ceramic scaffolds, containing cavities of several sizes, has been produced for deducing the best choice of cavity dimensions for culturing hepatocytes. The aim of this paper is to describe in detail the production methods and characterization of such ceramic scaffolds. Experimental production of the scaffolds consists of microfabrication of silicon templates as well as preparation and molding of titania ceramics. The templates, containing arrays of conical protrusions arranged in close-packed hexagonal order, have been achieved using microfabrication methods of photolithography and anisotropic etching in KOH at 50 °C. Protrusion dimensions and overall quality of the templates has been evaluated by scanning electron microscopy. The microfabricated templates have resulted in well-defined and reproducible cavities of corresponding dimensions on the titania ceramic surface after injection-molding. Alternatively, simple embossing of the plastified green ceramics with the silicon templates attached to a metal plate also creates cavities on the ceramic surface. While both methods yield good results, they have different advantages: the injection-molding provides a higher quality of imprints while embossing is quicker and less complicated, and is not limited by dimensions of specific molding equipment. © 2001 Kluwer Academic Publishers     

Terrain Reconstruction from Contours by Skeleton Construction

Generating terrain models from contour input is still an important process. Most methods have been unsatisfactory, as they either do not preserve the form of minor ridges and valleys, or else they are poor at modeling slopes. A method is described here, based on curve extraction and generalization techniques, that is guaranteed to preserve the topological relationships between curve segments. The skeleton, or Medial Axis Transform, can be extracted from the Voronoi diagram of a well-sampled contour map and used to extract additional points that eliminate cases of flat triangles in a triangulation. Elevation estimates may be made at these points. Based on this approach it is possible to make reasonable estimates of slopes for terrain models, and to extract meaningful intermediate points for triangulated irregular networks (TINs).     

Orders‐of‐Magnitude Reduction of the Contact Resistance in Short‐Channel Hot Embossed Organic Thin Film Transistors by Oxidative Treatment of Au‐Electrodes

In this study we report on the optimization of the contact resistance by surface treatment in short‐channel bottom‐contact OTFTs based on pentacene as semiconductor and SiO₂ as gate dielectric. The devices have been fabricated by means of nanoimprint lithography with channel lengths in the range of 0.3 μm < L < 3.0 μm. In order to reduce the contact resistance the Au source‐ and drain‐contacts were subjected to a special UV/ozone treatment, which induced the formation of a thin AuO_x layer. It turned out, that the treatment is very effective (i) in decreasing the hole‐injection barrier between Au and pentacene and (ii) in improving the morphology of pentacene on top of the Au contacts and thus reducing the access resistance of carriers to the channel. Contact resistance values as low as 80 Ω cm were achieved for gate voltages well above the threshold. In devices with untreated contacts, the charge carrier mobility shows a power‐law dependence on the channel length, which is closely related to the contact resistance and to the grain‐size of the pentacene crystallites. Devices with UV/ozone treated contacts of very low resistance, however, exhibit a charge carrier mobility in the range of 0.3 cm² V^–1 s^–1 < μ < 0.4 cm² V^–1 s^–1 independent of the channel length.     

Channel length variation in self-aligned,nanoimprint lithography structured OTFTs

We report on the fabrication and characterization of self-aligned organic thin-film transistors with copper gate electrodes structured by nanoimprint lithography (NIL). The process has been improved to increase the compatibility with solution processed materials for future fabrication of fully printed, NIL structured transistors. We provide detailed analysis of the influence of the channel length on the fabricated devices. The on-current, the swing and the onset voltage are studied for channel lengths between 25 μm and 800 nm. The results indicate that for the given system a channel length of 5 μm results in the best device performance regarding the on-current and the subthreshold swing. This work marks a first step towards our goal of fabricating self-aligned NIL OTFTs consisting solely of printable materials.     

国际品牌在中国的爱与痛

电视节目“我是歌手”里的茜拉说她有一个中国梦,这深深触动了我。其实,每个中国珠宝人都有一个中国梦,可是相比中国珠宝人的中国梦,外国著名品牌和珠宝商人想在中国实现的梦想似乎更巨大。     

Tangentially Coupled π Systems and their Through-Space Interaction – trichromophoric perylene dyes

Three perylene tetracarboxylic bisimide chromophores have been attached to a benzene ring in m-position ( 3 ). In this way steric and through-bond interactions of the chromophores are minimized and their through-space-interactions can be studied for which an unusually high bathochromic shift has been found. This indicates a destabilization. No exciton coupling has been observed in the trichromophoric dyes.