新旧建筑的承重结构

卡内基图书馆的扩建工程从开始就面临着原有建筑的复杂问题。因为此建筑被列入文物保护名单中．同时也是瓦特福特郡具有历史价值的建筑．所以完全毁坏重建既不是人们所希望的也不是正确的选择。除此之外．建筑两端还与繁华的商业街和零售点毗邻。     

Soft tissue response to glycerol-suspended controlled-release glass particulate

Vesicoureteral reflux and urinary incontinence have previously been treated by various means including the endoscopic delivery of injectable bulking materials such as silicone micro-implants, PTFE implants, glass particles, fat and bovine collagen. These first three materials do not degrade and collagen requires frequently repeated injections in order to sustain the restored continence provided. Vesicoureteric reflux in children usually resolves independently before the age of five. Correction is required before this, because treatment by prophylactic antibiotics is frequently unsuccessful in preventing breakthrough infection. The ideal material for injection should have large particles to avoid migration, inject easily and controllably, be non-toxic and dissolve over the period of time by which time the kidney will be mature. Three different controlled-release glass (CRG) granule compositions have been prepared by Giltech Ltd, and suspended in a suitable carrier medium (in this case glycerol). The degradable glasses, which have two different size ranges of 200–300 and <53 m, and three different solution rates, were injected intramuscularly into the dorso-lumbar region of rats. Histological analysis of cryostat cut section after time periods of 2 d, 4 and 9 wk, and 6 mon has been performed. Histology sections were stained for neutrophils and macrophages using enzyme histochemistry. ED1 (monocytes and immature macrophages), ED2 (mature tissue macrophages), CD4 (helper/inducer T-lymphocytes and macrophages), CD8 (suppresser/cytotoxic T-lymphocytes), Interleukin-1, IL-2 (activated T-lymphocytes), Major Histocompatibility Complex (MHC) class II (activated macrophages and activated B-lymphocytes), – (T-lymphocytes) and CD45RA (B lymphocytes) antibodies have beed used to stain immunohistochemically each sample. This study demonstrates that particulate, degrading glass is stimulating an inflammatory response in soft tissue at time periods up to 6 mon. It should be noted that very small particulate, fast degrading glass is leading to tissue necrosis and should not be considered further for these applications. However, larger particulate, slower degrading materials are demonstrating effective potential for stress incontinence applications. © 1998 Kluwer Academic Publishers     

High-extinction-ratio low-loss tightly bent PANDA fibre

The realisation of tightly bent PANDA polarisation maintaining fibre with minimal reduction of extinction ratio and throughput power is described for the miniaturisation of polarisation maintaining fibre circuits. After mechanically side-polishing the bare PANDA fibre, bend diameters as small as 1 mm have been achieved that preserve the fibre s extinction ratio ( 35 dB) with minimal loss ( 0.1 dB).     

Dispersion tolerance of coherent WDM

We present the transmission of a 298.2-Gb/s copolarized coherent wavelength-division-multiplexing system over 80 km of standard single-mode fiber, achieving an information spectral density of 1 b/s/Hz with no prefilters at the transmitter. Odd and even tributary channels were encoded with data and delayed-data-bar pseudorandom binary sequence 2/sup 7/-1 patterns. The dispersion tolerance is investigated, and the dispersion penalty of this system is improved through adjustment of the relative phase of adjacent channels. Under optimum conditions, the dispersion penalty could be reduced from over 3 dB to less than 1 dB.     

The influence of reserpine on the responsiveness to norepinephrine and electrolyte contents of rabbit atria

This study was designed to investigate the relationships between reserpine-induced supersensitivity and electrolyte levels in isolated rabbit atria. Atria from reserpine-treated (1, 3 or 4 mg/kg 24 hr before) and untreated rabbits were placed in an isolated organ bath for determination of dose-response relationships for norepinephrine, or were used for electrolyte assay. Reserpine-treated atria had greater resting and maximum rates of beat than did untreated atria. However, the ED50 concentrations of norepinephrine producing a rate response were similar. Atria pretreated with 1 or 3 mg/kg reserpine were supersensitive to the inotropic effect of norepinephrine. 4 mg/kg reserpine did not induce inotropic supersensitivity. Atrial sodium contents were significantly increased by 3 mg/kg reserpine. Potassium contents were increased by 1 and 4 mg/kg reserpine. Calcium contents were significantly decreased by 4 mg/kg reserpine, while magnesium contents were increased by 1 and 4 mg/kg. Reserpine induced supersensitivity to the inotropic effects of norepinephrine but did not alter the sensitivity to the chronotropic effect of the drug. This supersensitivity may be linked to alterations in the tissue's homeostatic mechanisms for calcium.     

Corrosion of oxide-coated titanium (DSA) anodes in organic solvents (especially methanol)

In certain organic solvents, notably alcohols (and in particular methanol), DSA-type anodes deteriorate rapidly under anodic conditions. The active RuO₂-based layer is itself quite resistant to corrosion; however, rapid dissolution of the titanium support through pores and cracks in the active oxide coating, eventually results in detachment of the surface layer. A survey of the titanium dissolution reaction in methanol, and (to a lesser extent) other common solvents, is reported first. Reaction was quite rapid in methanolic solutions at low pH, almost negligible in solutions of high pH, and inhibited in the former case on addition of increasing quantities of water or sulphuric acid. In similar experiments with oxide-coated titanium, the rate of metal dissolution in acidified methanol was reduced by addition to TiO₂ to the RuO₂ layer, increasing the active oxide loading, increasing the water or acid content of the solvent, use of low oxide annealing temperature, and operating at low current density. If this type of anode is operated in anhydrous alcohol systems, the use of a noble metal, or noble metal clad titanium, support would be worth considering. Of the other non-alcoholic solvents investigated, acetonitrile and propylene carbonate appeared to be more resistant to oxidation than dimethyl formamide or dimethyl sulphoxide — no trace of titanium dissolution was observed with any of these solvents.