Effect of die-casting conditions on viscoelastic behavior of Mg alloy

Creep and stress relaxation resistance of the most common die-cast Mg alloy AZ91D (Mg-9% Al-1% Zn) are influenced by both casting temperature and injection rate as well as by die temperature and porosity. Relationships between viscoelastic properties of Mg alloy at 150 °C and the parameters of die-casting technology are obtained and presented as simple contour plots (isograms). These properties can be improved by reducing casting temperature and increasing injection rate. When fabricating complicated thin-wall components, castability of the alloy can be diminished due to a fast temperature drop. In this case, casting temperature should be higher, whereas injection rate can be reduced. Porosity seems to be the most important characteristic of die-cast alloy microstructure affecting its viscoelastic properties. Coarse β-phase precipitates do not affect creep and relaxation characteristics of die-cast AZ91D alloy.     

Can umami taste be an adequate tool for reducing sodium in food preparations?

Researches indicate that the Brazilian population is still consuming sodium in excess and national epidemiological studies, have not verified the impact of taste modifications provided by the formulations available on the market and in homemade meals. The objective is to verify whether the basic umami taste, in the form of monosodium glutamate (MSG) monohydrate, is an alternative for reducing sodium in the preparation of meals. Also, to confirm the ideal concentration of MSG equivalent to acceptance with salt, and the impact of an explanatory video about warnings of salt excess on consumer behaviour, regarding the intention to use table salt in meals. For this study, three concentrations of sodium were used in the preparations rice and ground meat: one with the intrinsic sodium of the food, one with the addition of salt, 1 g for 100 g of rice and for meat, and one with salt and MSG, for 100 g of rice, 0.54% are of salt and 0.43% are of MSG and for 100 g of meat, 0.55% are of salt and 0.44% are of MSG. All quantities were suggested by a previous study, confirmed in a sensorial pre-test. The acceptability of preparations was assessed by the preference test. The levels of sodium and glutamic acid in the test preparations were also analysed. The results showed no significant difference between the exposed to the video. This study showed a sodium reduction of at least 30% in rice and 33% in ground meat, two kinds of meals widely consumed in Brazil, maintaining the same acceptance. These data suggest that the partial substitution of NaCl with MSG/umami can be an alternative to reduce sodium in meals.     

Experimental Determination of Correlations Between Spontaneously Formed Vortices in a Superconductor

We have imaged spontaneously created arrays of vortices (magnetic flux quanta), generated in a superconducting film quenched through its transition temperature at rates around 10⁹ K/s. From these images, we calculated the positional correlation functions for two vortices and for 3 vortices. We compared our results with simulations of the time dependent Ginzburg Landau equation in 2D. The results are consistent with the Kibble-Zurek scenario of spontaneous vortex creation. Effects due to fluctuations of the gauge field on the correlation functions are below our experimental resolution.     

A control loop which ensures high side-mode-suppression ratio in atunable DBR laser

The authors present a control loop which ensures single-mode operation of a tunable distributed-Bragg-reflector (DBR) laser. This control loop uses no external optics. The error signal is derived from an integrated detector which measures the light transmitted through the Bragg section. Using this signal to control the current to the Bragg section, the laser is tuned to where the side-mode-suppression ratio is high. This guarantees that the laser remains single-mode, even when modulated. This servo is capable of application in wavelength-division-multiplexed (WDM) systems     

Enhanced red cell sodium-hydrogen exchange in microvascular angina

OBJECTIVES: Enhanced calcium content in arterial smooth muscle cells and altered reactivity of coronary vessels to alkalinization have been reported in angina pectoris due to impaired motility of coronary arteries. An altered function of sodium-hydrogen exchange, a ubiquitous membrane transport system that links proton efflux to calcium drifts, may mediate these phenomena. DESIGN AND SUBJECTS: Twenty patients with microvascular angina (stable effort angina, reversible perfusion defects during effort thallium 201 heart scintigraphy, and angiographically normal coronary arteries) were compared to 20 patients with stable effort angina due to coronary atherosclerosis and 20 healthy subjects. The sodium-hydrogen exchange was defined as the initial fraction of the amiloride-sensitive proton efflux from red cells with inhibited anion exchanger (pHi 6.00-6.05) into an Na(+)-containing medium (pHo 8.00-8.05). 12-0-tetradecanoylphorbol-13-acetate (TPA, 600 nmol.l-1) and staurosporine (100 nmol.l-1) were used as phosphorylation modulators in vitro. RESULTS: The mean red blood cell Na+/H+ exchange was increased in patients with microvascular angina (451 +/- 37 vs 142 +/- 17 and 124 +/- 21 umol H+.1 cells-1.min-1, P < 0.01). TPA and staurosporine abolished differences between the groups. CONCLUSIONS: Microvascular angina is associated with enhanced Na+/H+ exchange in erythrocytes, probably due to more extensive phosphorylation of the membrane antiporter sites.     

40 GHz active mode-locking in a 1.5 mu m monolithic extended-cavity laser

Reports active mode locking in a monolithic long-cavity semiconductor laser, operating at 1.5 mu m wavelength. Pulses with durations of 4 ps at repetition rates up to 40 GHz have been achieved, with a modulation depth of 97%. This is the first report of active mode locking in a monolithic device, and the highest repetition rate achieved with an actively mode locked laser.<>     

The in vivo effect of recombinant human granulocyte-colony stimulating factor in neutropenic neonates with sepsis

The effects of recombinant granulocyte-colony stimulating factor (rhG-CSF) in neonatal neutropenia with presumed sepsis, which has a poor prognosis, were investigated. The study involved 14 neonates with presumed sepsis and neutropenia. Findings were compared with those from 24 historical controls. rhG-CSF (5 micrograms/ kg/day i.v. for 5 days) was administered immediately following diagnosis. Complete blood counts were obtained before and 24, 48, 72, 96 and 120 h after initiation of treatment. Neutrophil storage pool (NSP) was assessed (in 4 patients) before and after treatment. Statistical analysis was performed using one way analysis of variance. Treatment led to an increase in absolute neutrophil count (ANC) levels in 13/14 patients. At the end of treatment, the mean ANC was higher than that of controls (P = 0.007). There was a marked increase in the NSP of between 32% and 65% (P = 0.005). There were two clinical failures, one of whom was considered to have died from his underlying condition. There were no reports of clinical or haematological toxicity during treatment or follow up.     

A statistical study of defect maps of large area VLSI IC's

Defect maps of 57 wafers containing large area VLSI IC's were analyzed in order to find a good match between the empirical distribution of defects and a theoretical model. Our main result is that the commonly employed models, most notably, the large area clustering negative binomial distribution, do not provide a sufficiently good match for these large area IC's. Only the recently proposed medium size clustering model is close enough to the empirical distribution. An even better match can be obtained either by combining two theoretical distributions or by a “censoring” procedure in which the worst chips are ignored. Another goal of the study was to find out whether certain portions of either the chip or the wafer had more defects than the others     

Healing of the esophageal suture line: does it differ from the rest of the alimentary tract?

We investigated the healing pattern of the esophageal suture line in rats. Fifty male wistar rats were divided into experimental (n = 40) and control (n = 10) groups. The rats in the experimental group underwent esophogostomy at the abdominal esophagus, which was immediately sutured, and sacrificed 2, 4, 7 and 14 days later. Esophageal bursting pressure and hydroxyproline content were determined in both groups. The measured bursting pressures in the experimental group on days 2, 4, 7 and 14 were (mean +/- SD) 78 +/- 35, 95 +/- 12, 1,163 +/- 98 and 1,224 +/- 22 cm H2O, respectively, and 1,308 +/- 87 cm H2O in the control group (P <0.05 vs. all the experimental group values). The hydroxyproline content in the experimental group on days 2, 4, 7 and 14 were 13.9 +/- 2.1, 12.53 +/- 2.68, 15.6 +/- 0.85 and 17.75 +/- 5.65 microg/mg, respectively, and 27.88 +/- 2.5 microg/mg in the control group (P <0.05 vs. all the experimental group values). We conclude that the esophagus demonstrates the same healing pattern as the rest of the alimentary tract, but its healing seems to occur at a slower pace.     

Characteristics of distributed Bragg reflector active optical filters

The transfer function characteristics of distributed-Bragg-reflector (DBR)-based active optical filters are described. Small and large signal characteristics are presented, and a variety of nonlinear effects obtained in the large signal regime such as gain saturation, frequency pulling, and wavelength domain bistability are demonstrated. While these nonlinear effects may be detrimental to conventional filter applications, they may possibly be explored for new approaches in wavelength domain logic, switching, and routing. The filter can also be used in a reversed configuration. Compared to the characteristics described, the small signal transmission transfer function remains unchanged but the input power at which the nonlinear effects take place is increased by 20-30 dB. This is due to the much reduced reflected power inside the filter cavity. At the same time, however, the noise power added to the amplified signal is also significantly increased.<>