Thermomechanical characterization of stress localization in glass: An experimental and numerical study

Thermoelastic stress analysis and quantitative calorimetry are full‐field noncontact techniques widely used to study the thermomechanical behaviour of materials. The first one linearly relates the sum of the principal stresses to the temperature variation, and the second one can be used to measure the mechanical dissipation. However, brittle materials such as glass are a priori bad candidates for these techniques. Indeed, their low‐temperature variations under loading lead to very noisy infrared images, and their brittle mechanical behaviour does not allow to deform them significantly. In the present paper, the thermomechanical characterization of a holed glass sample under cyclic loading is performed. A preliminary new filtering methodology has been applied to the thermal movie to remove the noise. The stress field obtained from the thermoelastic stress analysis is well correlated to the finite element model showing that this technique is adapted to study the thermoelastic response of brittle materials. Finally, the corresponding calorimetric response has been determined by using a simplified formulation of the heat diffusion equation. This permits to quantify heat sources and to carry out energy balances.     

The effect of aluminium hydroxide orally on calcium, phosphorus and aluminium metabolism in normal subjects

1. Five normal subjects were given 100 ml of aluminium hydroxide gel per day for 28 days. 2. The phosphorus balance became more positive in one subject, less negative in two and changed from negative to positive in the other two subjects. This was accompanied by a rise in the concentration of the fasting morning plasma phosphorus. Calcium balance did not change. 3. The normal subjects absorbed 0-3-3-6 mmol of aluminium/day, which is significantly less than that absorbed by five patients with chronic renal failure, three of whom were studied before, and two after, the observations on the normal subjects had been completed. 4. In a further five normal subjects on 100 ml of aluminium hydroxide gel/day the 08.00 hours concentration of plasma phosphorus did not fall, though there was a fall at 11.00, 14.00 and 17.00 hours.     

A new typhoid vaccine composed of the Vi capsular polysaccharide

Typhoid is still prevalent in many parts of the world. We reviewed all published and unpublished studies of a newly licensed vaccine composed of the Vi capsular polysaccharide of Salmonella typhi, the causative agent of the disease, which had been licensed previously outside the United States. These included observational studies and double-blind randomized studies done in the United States, Europe, and the developing world in which children and adults unexposed to typhoid or those living in endemic areas were enrolled. A single dose of 25 micrograms of the purified polysaccharide was given by intramuscular injection. The vaccine was well tolerated, inducing only minor reactions in fewer than 10% of subjects. An antibody response occurred in about 90% of subjects and lasted about 3 years. Seroconversion was shown in children as young as 2 years. Protective efficacy was evaluated in two studies conducted in areas in which typhoid is endemic; the efficacy was 55% and 75%, respectively, in adults and in children older than 5 years. The Vi vaccine compares favorably with other typhoid vaccines in regard to safety, patient compliance, immunogenicity, and efficacy. Vi polysaccharide is a well-standardized antigen that is effective in a single parenteral dose, is safer than whole-cell vaccine, and may be used in children 2 years of age or older.     

Effect of different experimental parameters on the potentiometric evaluation of blood electrolytes using K+ as a test cation

Potentiometric evaluation of ionic concentrations in physiological media has been reported to be significantly affected by the albumin containing matrix. Previous studies have attempted to clarify the origin of different patterns of variation of E versus albumin concentration at a constant 0.01 mol dm-3 KCl, depending on the experimental methodologies. This paper reports on measurements of K+ in albumin (BSA) containing KCl solutions, which have been pursued following different methodologies concerning the sequence of measurements, i.e., starting either from the most concentrated solution (100 g dm-3) (A) or from the most dilute solution (20 g dm-3) (B), and solution preparation, (a) dilution of an initial 100 g dm-3 albumin solution by successive addition of 0.01 mol dm-3 KCl, (b) concentration of an initial 20 g dm-3 albumin solution by addition of solid substance, (c) independent preparation of each albumin solution (20, 40, 60, 80 and 100 g dm-3) or (d) preparation of each albumin solution from direct dilution of a 100 g dm-3 stock solution with 0.01 mol dm-3 KCl. Convenient calculations were made and showed a significant contribution of albumin to the liquid-liquid junction potential. The variation of potential with albumin concentration is smaller for hypertonic than for isotonic bridge solutions, both for the dilution series (A,a and A,d) and for the concentration series (B,c and B,d). When the method for increasing the concentration is performed by addition of a solid substance to an initially diluted albumin (B,b), the slope of the E versus albumin concentration plot is larger for hypertonic than for isotonic reference electrolytes. This latter finding is in agreement with Payne's results when ultrafiltration was used to concentrate a protein solution. These observations are a clear indication that the method of preparation of concentrated protein solutions may significantly affect the results.     

EURECA: European-Japanese Microcalorimeter Array

The EURECA project aims to demonstrate technological readiness of a micro-calorimeter array for application in future X-ray astronomy missions, like Constellation-X, EDGE, and XEUS. The prototype instrument consists of a 5×5 pixel array of TES-based micro-calorimeters read out by two SQUID-amplifier channels using frequency-domain-multiplexing (FDM) with digital base-band feedback. The detector array is cooled by a cryogen-free cryostat consisting of a pulse tube cooler and a two stage ADR. Initial tests of the system at the PTB beam line of the BESSY synchrotron showed stable performance and an X-ray energy resolution of 1.5 eV at 250 eV for read-out of one TES-pixel only. Next step is deployment of FDM to read-out the full array. Full performance demonstration is expected end 2008.      

Node Re-Routing and Congestion Reduction Scheme for Wireless Vehicular Networks

Recently, the interest of research is going to be focused on the emerging vehicular ad-hoc networks paradigm. In these networks, vehicles communicate with each other and have the possibility of exploiting a distributed approach, typical of ad-hoc networks, which allow mobile nodes (vehicles) to communicate with each other. Thanks to the different standards for this kind of network, such as DSRC, WAVE/IEEE802.11p, the researchers have the possibility of designing and developing new MAC and routing algorithms, trying to enhance the mobile users experience in the mobile environment. In this paper, the attention is focused on the optimization of traffic flowing in a vehicular environment with vehicle-2-roadside capability. The proposed idea exploits the information that is gathered by road-side units with the main aim of redirecting traffic flows (in terms of vehicles) to less congested roads, with an overall system optimization, also in terms of Carbon Dioxide emissions reduction. A deep campaign of simulations has been carried out to give more effectiveness to our proposal.     

Partial preservation of pancreatic beta-cells by vanadium: evidence for long-term amelioration of diabetes

Streptozotocin (STZ)-diabetic rats treated with vanadium can remain euglycemic for up to 20 weeks following withdrawal from vanadium treatment. In this study, we examined the effects of short-term vanadium treatment in preventing or reversing the STZ-induced diabetic state. Male Wistar rats were untreated (D) or treated (DT) with vanadyl sulfate for 1 week before administering STZ. Treatment was subsequently maintained for 3 days (DT3) or 14 days (DT14) post-STZ, after which vanadium was withdrawn. At 4 to 5 weeks post-STZ and following long-term withdrawal from vanadium, DT14 rats demonstrated levels of food and fluid intake and glucose tolerance that were not significantly different from those of age-matched untreated nondiabetic rats, and had significantly reduced glycemic levels in the fed state compared with D and DT3 groups. The proportion of animals that were euglycemic (fed plasma glucose < 9.0 mmol/L) was significant in DT14 (five of 10) relative to D (one of 10) and DT3 (one of 10) (P = .01). All euglycemic animals had an improved pancreatic insulin content that, albeit low (12% of control), was strongly linked to euglycemia in the fed state (r = -.91, P < .0001). Moreover, the highly significant correlation persisted with the analysis of untreated STZ-rats alone (r = -.95, P < .0001). Similarly, improvements in glucose tolerance and insulin secretory function in euglycemic rats were strongly correlated with small changes in residual insulin content. Hence, as vanadium pretreatment did not prevent STZ-induced beta-cytotoxicity, the vanadium-induced amelioration of the diabetic state appears to be secondary to the preservation of a functional portion of pancreatic beta cells that initially survived STZ toxicity. The partial preservation of pancreatic beta cells, albeit small in proportion to the total insulin store, was both critical and sufficient for a long-term reversal of the diabetic state. These results suggest that apparently modest effects in preserving residual pancreatic insulin content can have profound consequences on glucose homeostasis and may bear important implications for interventions that have "limited" protective effects on beta cells.     

Strawberry drying: Development of a closed-cycle modified atmosphere drying system for food products and the performance evaluation of a case study

In the present study, a closed-cycle modified atmosphere drying (CC-MAD) system was developed as an alternative drying technique to facilitate drying processes for agricultural commodities appropriate to highly humid and sunny regions with a better quality. An absorption dehumidifying system was designed for working pseudo-continuously with the most efficient absorbent in terms of moisture absorption, desorption rate, and capacity. The system, assisted by a solar panel for absorbent regeneration, was tested, while its optimum working condition was determined by strawberry drying. This unique process was comparatively carried out using hot-air and freeze-drying techniques in terms of processing time and final product quality. Strawberry slices (5?mm thickness) were dried successfully using CC-MAD. The optimum drying conditions of CC-MAD were determined as drying temperature of 60°C, drying air/gas velocity of 3?m/s and drying medium oxygen level of 9.47%. The loss of ascorbic acid was significantly reduced by CC-MAD technique. These losses were found to be 2.9, 6.9, 27.2, and 23.8% by freeze-drying, CC-MAD, hot-air drying, and hot-air drying combined with CC-MAD, respectively. The total monomeric anthocyanins loss was also significantly reduced by the CC-MAD technique (20.3%), in a similar way to that of freeze-drying (18.1%) in comparison with hot-air drying (40.4%). In addition, CC-MAD (12,446?kJ/kg fresh product at 4?h drying time) is three times more advantageous in terms of energy cost compared with freeze-drying (30492.8?kJ/kg fresh product at 24?h drying time) and six times faster in terms of drying time. This new drying system can be used as an alternative to freeze-drying in the drying of foods, especially in products sensitive to oxidation.     

Characterisation of Pomegranate Juices from Ten Cultivars Grown in Turkey

Pomegranate juices obtained from ten pomegranate cultivars of Turkey were analysed for their sugars, organic acids and the other quality parameters including pH, total soluble solids, and titratable acidity. Statistically significant differences were determined among the cultivars for parameters analysed. Citric acid was the predominant acid of all the cultivars studied. Cultivar “Zivzik,” one of the most popular cultivar in Turkey, showed best scores for total soluble solids (16.9 ± 0.06 °Brix), glucose (84.18 ± 0.42 g/l) and fructose (83.34 ± 0.81 g/l). Pomegranate juices were classified into three groups according to principal component analysis and cluster analysis.