Subanesthetic concentrations of isoflurane suppress learning as defined by the category-example task

It has been shown that chronic oral steroid therapy (ST) does not induce respiratory muscle dysfunction in normal and asthmatic subjects. As corticosteroids are sometimes chronically used in the treatment of the patients with chronic obstructive pulmonary disease (COPD), the aim of our study was to verify whether ST could cause respiratory muscle impairment and, since ST also affects the central nervous system, whether ST could influence the ventilatory pattern. We retrospectively studied 12 COPD patients (group A), on long-term therapy (for at least 4 consecutive months, range 4-18 months) with an oral steroid, deflazacort, 15 mg.d-1. The subjects were strictly matched, with regard to age, sex, height, weight, forced expiratory volume in one second (FEV1), residual volume (RV), arterial oxygen tension (PaCO2), arterial carbon dioxide tension (PaCO2) and pH, with 12 COPD patients (Group B) who had never taken oral steroids. To assess respiratory muscle strength, we measured maximal inspiratory (MIP) and expiratory (MEP) pressures, while mouth occlusion pressure (P0.1) was employed to assess neuromuscular drive; ventilatory pattern and airway impedence were also evaluated. Effectiveness of ST was confirmed by the plasmatic levels of endogenous cortisol. No significant differences were observed between the two groups with regard to MIP (A 72.2 +/- 9.7 vs B: 70 +/- 7.2 cmH2O) and MEP (A 91.6 +/- 10.5 vs B 94.4 +/- 7.6 cmH2O) whilst P0.1 was significantly higher in group A (2.6 +/- 0.3 cmH2O) than in group B (1.8 +/- 0.1 cmH2O). No significant differences were found among all the ventilatory parameters, but the impedence was significantly higher in group A.(ABSTRACT TRUNCATED AT 250 WORDS)     

Well-differentiated liposarcoma of the hypopharynx

We report a case of subacute bowel obstruction due to a compression of the rectosigmoid junction by a chronically distended bladder, occurring in a 91-year-old male suffering from a long-standing diabetes mellitus and a prostatic adenoma. Radiographic, water-soluble contrast enema and pelvic CT features are reported.     

Age-related changes in sympathetic modulation of sensory nerve activity in rat skin

OBJECTIVES: Sensory nerves play an important role in mediating neurogenic inflammation and subsequent tissue healing. A decrease in sensory nerve function with increasing age has been reported to correlate with poor tissue healing. Sympathetic nerves are known to modulate sensory nerve function, and changes in this modulation could also have important implications with ageing. The aims of this study were to examine the effect of different frequency electrical stimulation (ES) on the microvascular responses obtained to sensory nerve activation in young, aged and capsaicin-pretreated rats and modulation of these responses by sympathetic efferents. METHODS: Using laser Doppler flowmetry, vascular responses to antidromic ES of the sciatic nerve were monitored in the base of vacuum-induced blisters in the hind footpad. The non-selective alpha-adrenoceptor antagonist phentolamine (3 mg/kg, i.v.) was administered 20 min prior to ES. RESULTS: At high frequency ES (20V, 2ms, 15Hz for 1 min), the vascular response in old rats was significantly reduced (46 percent decrease, p < 0.05) compared to young control. At low frequency ES (20 V, 2 ms, 5 Hz for 1 min) however, older rats produced similar vascular responses to the young. Capsaicin-pretreated rats showed significantly reduced vascular responses to both high and low frequency ES, regardless of age. Pretreatment with phentolamine significantly increased the microvascular response in young rats at high (87 percent) and low (36 percent) frequency ES. In contrast, phentolamine significantly increased the ES-induced response in old rats at high frequency only (147 percent increase). CONCLUSIONS: The results suggest that the aged sensory nerve responds preferentially to low frequency ES and that sympathetic efferents exert an inhibitory modulatory effect on the vascular response evoked by sensory nerve stimulation. There are age-related changes in sympathetic modulation of sensory nerve-mediated responses which is dependent on stimulation frequency.     

The Valve Metal Character of Zirconium as inferred from anode potential measurements in mineral acid solutions

A study on the value metal character of Zr in 0.1 M solutions of H₂SO₄, HNO₃, and H₃PO₄ has been performed using the anode potential as the primary variable in galvanostatic, potentiostatic, and capacity measurements. A method of surface pre-treatment, which suppresses both O₂ evolution and metal dissolution, has been described. Kinetic parameters of oxide growth have been calculated. The results indicate that:

• (i) the high field approximation is applicable following an exponential law, and
• (ii) the height and activation distance of the energy barrier for ion transport through the oxide phase (Verwey model) are the same three acids.

Measurements have been also made on the dielectric breakdown of oxide, and this occurs at potentials above 200 V. Direct capacity measurements give similar results as those based on reciprocal capacity calculated from galvanostatic experiments. It is concluded that the dominant anodic oxide species is ZrO₂ having a dielectric constant of 25. Open circuit potential measurements show that Zr is spontaneously oxidized in the three acids.     

Application of a hybrid finite element method to determine stress intensity factors in unidirectional composites

In this paper a hybrid finite element method is applied in evaluation of the stress intensity factors K _I and K _II of unidirectional fiber reinforced composites. In order to satisfy the stress singularity at the crack tip a singular super-element based on a modified complementary energy principle is developed. The stress and displacement fields in the super-element are expressed in terms of polynomials of two complex variables ₁ and ₂ in the transformed -plane. The stiffness matrix of the super-element was determined by using a line integral along the boundary of the super-element. The displacement vector was expressed in terms of the element nodal displacement vector {q} and a properly selected shape function defined along the element boundary.Numerical results for K _I and K _II of glass-epoxy and graphite-epoxy unidirectional composites with cracks along the diameter of a circular cut out as well as elliptical cut outs were evaluated

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Résumé On applique, dans la présente étude, une méthode d'éléments finis hybrides à l'évaluation des facteurs d'intensité de contrainte K_I et K_II pour des composites renforcés de fibres unidirectionnelles. Pour tenir compte de la singularité de la contrainte à l'extrémité de la fissure, on développe un super élément singulier en se basant sur un principe modifié d'énergie complémentaire. Les champs de contraintes et de déplacements dans le super-élément sont exprimés sous forme polynormale de deux variables complexes ₁, et ₂ dans le plan de la transformée. La matrice de rigidité du super élément est, quant à elle, définie en utilisant une intégrale linéaire le long du contour de l'élément. Le vecteur de déplacement est exprimé par un vecteur (9) de déplacement nodal de l'élément, et par une fonction de forme appropriée, définie le long du contour de l'élément.On évalue les résultats numériques pour K_I et K_II, correspondant à des composites à fibres unidirection-nelles de types verre-epoxy et graphite-epoxy, oú des fissures se situeraient sur le diamètre de découpes circulaires et elliptiques

     

Analytical studies on the temperature distribution in spiral plate heat exchangers: Straightforward design formulae for efficiency and mean temperature difference

The temperature distribution in spiral plate heat exchangers has been calculated numerically to obtain the efficiency and the logarithmic mean temperature difference (LMTD) correction factors F as a function of the number of transfer units N, the number of turns n, and the heat capacity rate ratio C. It has been found that the LMTD correction factors, when plotted against the number of transfer units per turn N/n, fall approximately on a single curve. That curve for balanced countercurrent operation (C = −1) can be very closely represented by the simple formula F = (n/N)tanh(N/n). From that simple analytic representation of our numerical results it was concluded that a simpler physical model might exist to represent the overall behaviour of a spiral plate heat exchanger equally well. In fact, a countercurrent cascade of n cocurrent heat exchangers does result exactly in the above-mentioned formula for the LMTD correction factor. From that model the F-factors for other heat capacity rate ratios C (−1 < C 0) can also be calculated and they are in sufficient agreement with the numerical results.     

Antimicrobial protection of cotton and cotton/polyester fabrics by radiation and thermal treatments. I. Effect of ZnO formulation on the mechanical and dyeing properties

Cotton and cotton/polyester fabrics were treated against microbial attack by applying a formulation based essentially on ZnO under high‐energy radiation and thermal curing. To achieve the homogeneity and the reactivity of the treating formulation, a binder (Impron MTP) and a dispersing agent (Setamol WS) were used with ZnO. The antimicrobial property of the fabrics was evaluated, in terms of mechanical properties, by a soil burial test. Moreover, the effect of antimicrobial finishing on the dyeing properties in terms of color strength was investigated. It was found that the best composition that affords the best antimicrobial protection to cotton fabrics contains 2% ZnO, 2% binder, and 1% dispersing agents. For the cotton/polyester blend, the best results were achieved at the same conditions except the ZnO was 1%. It was found that the treatment under the effect of electron‐beam irradiation is better than that of gamma irradiation and thermal curing. The results showed that when the finishing process was carried out before dyeing with a reactive dye, it affects the color strength rather than performing the finishing after the dyeing process. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 1129–1137, 2003     

Synthesis and characterization of new flame‐retardant poly(amide‐imide)s containing phosphine oxide and hydantoin moieties in the main chain

Six new flame‐retardant poly(amide‐imide)s (PAIs) 9a–f with high inherent viscosities containing phosphine oxide and hydantoin moieties in main chain were synthesized from the polycondensation reaction of N,N′‐(3,3′‐diphenylphenylphosphine oxide) bistrimellitimide diacid chloride 7 with six hydantoin derivatives 8a–f by two different methods such as solution and microwave assisted polycondensation. Results showed that the microwave assisted polycondensation, by using a domestic microwave oven, proceeded rapidly, compared with solution polycondensation, and was completed in about 7–9 min. All of the obtained polymers were fully characterized by means of elemental analysis, viscosity measurements, solubility test, and FTIR spectroscopy. Thermal properties and flame retardant behavior of the PAIs 9a–f were investigated using thermal gravimetric analysis (TGA and DTG) and limited Oxygen index (LOI). Data obtained by thermal analysis (TGA and DTG) revealed that these polymers showed good thermal stability. Furthermore, high char yields in TGA and good LOI values indicated that these polymers are capable of exhibiting good flame retardant properties. These polymers can be potentially utilized in flame retardant thermoplastic materials. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 5062–5071, 2006