Process for the formation of biaxially oriented films of poly(p-phenylene terephthalamide) from liquid crystalline solutions

A new process for making equal biaxially oriented films from liquid crystalline solutions of poly(p-phenylene terephthalamide) (PPD-T) is described. The process involves extruding solutions of PPD-T/H₂SO₄ through an annular die and over an oil-coated mandrel into a coagulation bath. The films were studied using wide angle X-ray diffraction (WAXS) and scanning electron microscopy (SEM). Tensile stress–strain properties were obtained on samples cut at various directions in the plane of the film. Biaxially oriented films which possess equal properties in the various directions in the plane of the film were produced. Moduli of 2.3 × 10⁹ Pa and tensile strengths of 9.6 × 10⁷ Pa were obtained in the plane of the film. Films with unequal biaxial orientation were also produced. These tend to have higher modulus/tensile strength in the direction of major orientation, the machine direction (up to 8.3 × 10⁹ Pa/2.5 × 10⁸ Pa), but become brittle in the transverse direction.     

Performance of a single glazing assembly exposed to enclosure corner fires of increasing severity

The results of 19 experiments in which a single pane glazing assembly was exposed to enclosure corner fires of increasing severity are presented. The glazing assembly was exposed to a two zone fire enclosure environment, with consistency and repeatability within each set of three experiments conducted at each fire severity level, evident from the enclosure gas temperature profiles. The results presented include heat release rates, enclosure and local gas temperatures, heat flux distributions, glass surface temperatures, shaded glass temperatures thermally induced stains, crack bifurcation patterns and loss of integrity of the glazing assembly. The results and observations obtained are presented in the form of a toolkit for the estimation of the occurrence of cracking and failure of single glazing in enclosure fires. Copyright © 2001 John Wiley & Sons, Ltd.     

Combining near infrared spectroscopy and multivariate analysis as a tool to differentiate different strains of Saccharomyces cerevisiae: a metabolomic study

Near-infrared (NIR) spectroscopy has gained wide acceptance within the food and agriculture industries as a rapid analytical tool. NIR spectroscopy offers the advantage of rapid, non-destructive analysis and routine operation is simple and opens the possibility of using spectra to obtain the 'fingerprint' of a sample. The aim of this study was to explore the potential of combining visible (VIS) and near-infrared (NIR) spectroscopy, together with multivariate analysis, in establishing the function of genes, by investigating the metabolic profiles produced by Saccharomyces cerevisiae deletion strains sourced from the EUROSCARF yeast collection. Spectra (400-2500 nm) were acquired with a FOSS NIRSystems6500 (Foss NIRSystems), in transmittance mode. Principal component analysis (PCA) and linear discriminant analysis (LDA) were used in order to visualize graphically the relative differences and similarities of yeast deletion strains. VIS and NIR spectroscopy showed great promise as a screening tool for both discriminating between yeast strains and grouping strains with deletions in genes that disturb similar metabolic pathways. These results indicate that the methods may be useful in defining the function of genes that produce no obvious phenotype.     

Relationship between Surface Roughness,Internal Crystal Perfection,and Crystal Growth Rate

Potential mechanisms affecting growth rate dispersion (GRD) are investigated. Previous studies have identified surface roughness and internal lattice perfection as key mechanisms which are both evaluated with respect to GRD. Crystal growth of potassium dihydrogen phosphate was studied in two solvent mixtures, water and water‐ethanol. The surface roughness was analyzed by atomic force microscopy and the internal crystal perfection by X‐ray diffraction using a synchrotron source. The crystals grown at higher supersaturation have more pronounced and more frequent surface irregularities, supporting previous findings on a feedback mechanism between surface roughness and growth rate. No significant relationship was found between internal crystal perfection and growth rate, however, this is likely due to the size of the crystals analyzed herein and not the absence of any such mechanism in small crystals.     

Unusual Crystal Growth Kinetics of (RS)‐Ibuprofen from Ethanolic Solutions

The solubility, secondary nucleation threshold, and growth kinetics of (RS)‐ibuprofen have been studied in an aqueous ethanol solvent. The metastable zone for secondary nucleation is very narrow at lower temperatures in this range, but greatly enlarged at higher temperatures. The crystal growth kinetics not only display significant dispersion of growth rates, but also a dead zone that is dependent on the growth rates of the crystals. Faster growing crystals display almost no dead zone, whereas the smallest crystals have a large dead zone. The size of the dead zone is largely responsible for the dispersion of crystal growth rates, perhaps due to differences in the thermodynamic stability of the different crystals. The mechanism of growth rate dispersion relates to that of the dead zone.     

Comparison of temperature dependence in C-band and L-band EDFAs

Temperature-dependent gain and noise characteristics of conventional band and long wavelength band erbium-doped fiber amplifiers are compared. Gain variations and noise figure penalties are shown for 980- and 1480-nm pump wavelength bands at different average inversion levels when the erbium coil temperature is cycled from -10°C to 80°C. Experimental results demonstrate that the L-band exhibits greater temperature-dependent gain and noise figure excursions compared to the C-band. Furthermore, it is shown that the impact of erbium coil temperature in the L-band is comparatively less dependent upon pump wavelength     

How do HMOs achieve savings? The effectiveness of one organization's strategies

OBJECTIVE: To examine how a group practice used organizational strategies rather than provider-level incentives to achieve savings for health maintenance organization (HMO) compared to fee-for-service (FFS) patients. DATA SOURCES/STUDY SETTING: A large group practice with a group model HMO also treating FFS patients. Data sources were all patient encounter records, demographic files, and clinic records covering 3.5 years (1986-1989). The clinic's procedures to record services and charges were identical for FFS and HMO patients. All FFS and HMO patients under age 65 who received any outpatient services during approximately 100,000 episodes of the seven study illnesses were eligible. STUDY DESIGN: Using an explanatory case design, we first compared HMO and FFS rates of resource utilization, in standardized dollars, which measured the impact of organizational strategies to influence patient and provider behavior. We then examined the effect of HMO insurance and organizational measures to explain total outpatient use. Key variables were standardized charges for all outpatient services and the HMO's strategies. PRINCIPAL FINDINGS: Patient and provider behavior responded to organizational strategies designed to achieve savings for HMO patients; for instance, HMO patients used midlevel providers and generalists more often and ER and specialists less often. Overall HMO savings, adjusted for case mix, were explained by the specialty of the physicians the patients first visited and appeared to affect patients with average health more than others. CONCLUSION: Organizational strategies, without resort to differential financial incentives to each provider, resulted in lower rates of outpatient services for HMO patients. Savings from outpatient use, especially for common diseases that rarely require hospitalization, can be substantial.     

Modulation of secreted beta-amyloid precursor protein and amyloid beta-peptide in brain by cholesterol

The effects of dietary cholesterol on brain amyloid precursor protein (APP) processing were examined using an APP gene-targeted mouse, genetically humanized in the amyloid beta-peptide (Abeta) domain and expressing the Swedish familial Alzheimer's disease mutations. These mice express endogenous levels of APP holoprotein and abundant human Abeta. Increased dietary cholesterol led to significant reductions in brain levels of secreted APP derivatives, including sAPPalpha, sAPPbeta, Abeta1-40, and Abeta1-42, while having little to no effect on cell-associated species, including full-length APP and the COOH-terminal APP processing derivatives. The changes in levels of sAPP and Abeta in brain all were negatively correlated with serum cholesterol levels and levels of serum and brain apoE. These results demonstrate that secreted APP processing derivatives and Abeta can be modulated in the brain of an animal by diet and provide evidence that cholesterol plays a role in the modulation of APP processing in vivo. APP gene-targeted mice lacking apoE, also have high serum cholesterol levels but do not show alterations in APP processing, suggesting that effects of cholesterol on APP processing require the presence of apoE.     

Effect of intravesical capsaicin and vehicle on bladder integrity control and spinal cord injured rats

PURPOSE: To determine the acute effect of intravesical capsaicin on bladder mucosal integrity in normal and spinal cord injured (SCI) rats. MATERIALS AND METHODS: Intravesical reagents were instilled in 5 groups of age and weight matched female rats: 1) control + normal saline solution (NSS), 2) control + ethanol (EtOH), 3) control + capsaicin/EtOH, 4) SCI + NSS, 5) SCI + capsaicin/EtOH. Intravesical instillations were performed 4 weeks after a standard T10 SCI. Intravesical capsaicin (1 mM.) was dissolved in 30% EtOH/NSS. The animals (n = 3 each group) were sacrificed at 30 minutes, 24 hours, 72 hours, and 7 days after intravesical instillation. Whole bladders were harvested, fixed in 10% buffered formalin, and paraffin embedded. Tissue blocks were blind coded and sectioned (5 microns thickness) for histopathological analysis. All sections were initially stained with hematoxylin and eosin (H & E). Specific staining for mucin carbohydrate moieties included periodic acid-Schiff (PAS) and alcian blue. Also, immunohistochemical staining for GP51 (a urinary glycoprotein) was performed. RESULTS: Control and SCI rats exhibited similar bladder mucosal histology by H & E and mucin specific stains. Instillation of saline demonstrated no effect on bladder histology, whereas instillation of intravesical capsaicin induced a profound acute effect of thinning of the epithelium, submucosal edema, and diminished presence of GP51. EtOH produced similar pathological findings, but to a lesser degree than capsaicin. Intravesical capsaicin demonstrated a similar effect in both control and SCI animals. The peak effect was seen after 30 minutes and continued for 24 hours. Partial recovery was noted after 72 hours and complete recovery was evident by 1 week. CONCLUSIONS: The control and SCI rats demonstrated a histologically similar mucosa and glycosaminoglycan layer. The effect of saline instillation on the mucosa was negligible. Intravesical capsaicin dissolved in 30% ethanol/NSS had a profound effect on the bladder urothelium submucosa that was more pronounced than that seen with the ethanol vehicle alone in normal animals.