Downward Flame Spread Rate Over PMMA Rods Under External Radiant Heating

Fire Technology - There are multiple situations in which fires may occur at environmental conditions that are different than standard atmospheric conditions. Changes in ambient pressure, oxygen...     

A parallel-hybrid drive-train for propulsion of a small scooter

The paper presents the results of a two year study regarding the use of an innovative drive-train, having a parallel-hybrid structure, in a small scooter, in which a conventional internal combustion engine is coupled with an electric motor for the vehicle propulsion. The developed architecture enhances the maximum vehicle power, by exploiting the braking energy (by recovering it into the provided electrochemical accumulator), and operating the vehicle in zero emission mode for limited ranges. Moreover, it allows for recharging the inner battery from the electric mains, which is extremely appealing in terms of operating costs. According to the simulation results, the hybridization is able to enhance the maximum power of the scooter by 1.1 kW (around 50%), without changing the fuel consumption, and to allow a pure-electric operation with a range of 15-20 km; when the propulsion power comes only from the onboard batteries, and they are recharged from the electric mains, the operation cost per km is around a quarter the cost of corresponding fuel consumption of a vehicle without hybridization.     

Specific increase of L-dopa levels in plasma upon infusion of tyrosinase containing liposomes

1. The present paper reports the effects of liposome-entrapped tyrosinase (EC 1.14.18.1. L-Tyrosine, L-3,4-dihydroxyphenylalanine: oxygen oxidoreductase) infusion on the catecholamine contents of rat plasma. The actions of liposomes and free tyrosinase have also been investigated. 2. From the experiments, evidence has been obtained that liposome-entrapped tyrosinase is able to affect specifically L-3,4-dihydroxyphenylalanine (L-DOPA) levels which increase dramatically. 3. The possible use of liposome-entrapped tyrosinase to raise L-DOPA levels in catecholamine related disorders is discussed. 4. Liposomes without tyrosinase provoke no significant changes of catecholamine or L-DOPA levels while free tyrosinase does induce a change but in a less constant fashion than the liposome-entrapped enzyme.     

Cardiovascular responsiveness to physiological agonists of male rats made hypertensive by long-term exposure to cadmium

The mechanisms by which cadmium may affect cardiovascular regulation are controversial. In this study, we investigated haemodynamics and cardiovascular reactivity to various physiological agonists in anaesthetized male Sprague-Dawley rats which received, for 190 days, deionized drinking water containing 0 (control), 10 and 20 micrograms/ml of cadmium (as acetate). Systolic and diastolic blood pressure, as well as cardiac inotropism, were increased in a similar manner in the two groups of treated rats. Heart rate was reduced in the rats exposed to the higher dose of cadmium, while no electrocardiographic alteration was demonstrated. Cadmium exposure reduced the pressor responses following intravenous norepinephrine (0.25-1 microgram/kg), angiotensin I (0.25-1 microgram/kg) and higher doses of epinephrine (0.50 and 1 microgram/kg) as well as the depressor responses to bradykinin (0.40-1.6 microgram/kg). On the other hand, the exposed rats showed an increased vascular responsiveness to the beta-adrenoceptor stimulating effects of lower doses of epinephrine (0.125 and 0.25 microgram/kg). Moreover, the effects on blood pressure, heart rate and cardiac inotropism of graduated doses of intravenous acetylcholine, angiotensin II, histamine and serotonin were unchanged. Cadmium was accumulated in the kidney of the treated rats at levels similar to those found in exposed humans. Renal copper and zinc were also augmented, possibly in relation to the cadmium-induced synthesis of metallothionein, a protein able to bind different metals. On the whole, this study suggests that cadmium affects several neurohumoral mechanisms that regulate cardiovascular function. It is likely that the changes in these mechanisms have additive effects, under a possible influence of genetic and/or environmental variables, in determining cardiovascular alterations.     

Gelatin nanoparticles produced by a simple W/O emulsion as delivery system for methotrexate

Biodegradable hydrophilic gelatin nanoparticles, containing different initial amounts of methotrexate (MTX), were prepared using a simple solvent evaporation technique based on a single water-in-oil emulsion and stabilized by the use of glutaraldehyde as cross-linking agent. The effects of several parameters on particle size, drug encapsulation efficiency and drug release were investigated. Size and shape of the nanoparticles were examined by scanning electron microscopy. The release of MTX was monitored in vitro and the mechanism of release was studied. Particles with a mean diameter of 100–200 nm were produced, which were able to release MTX following a diffusion-controlled mechanism of release. It was observed that the initial amount of MTX used for sample loading did not have any effect on the pattern of release, while it affected the amount of drug entrapped into the nanoparticles and also both the release rate and the total amount of drug released.     

Modified QFD and problem‐solving techniques integrated approach implementing corrective actions: a case study in an Italian manufacturing plant

The ISO 9001:2000 and Total Quality Management models impose that organizations adopt structured procedures to implement corrective and preventive actions. In this paper, a structured framework to solve a non‐conformity in a product or in a process, selecting the best corrective actions, is proposed. Some problem‐solving techniques are applied in a structural method (i) to find the problem (product or process non‐conform), (ii) setting the problem (using data‐collecting instruments), (iii) analyzing the problem (with techniques such as Pareto charts, histograms, stratification analysis) and (iv) searching possible alternative solutions. Then, a modified quality function deployment technique is applied to evaluate and to classify the alternative solutions with respect to three different parameters (benefit, cost and impact). The framework has been developed to select and implement corrective actions in an Italian manufacturing plant. The case study is presented in this paper. However, the proposed approach is applicable in many other contexts. Copyright © 2008 John Wiley & Sons, Ltd.     

Correlation of Burning Rate with Spread Rate for Downward Flame Spread Over PMMA

Burning rate of solid fuel and laminar flame spread rate are both well studied topics for flame spread in downward configuration. Yet, despite well-developed theories, not much experimental data is available to correlate the two. In this work, experiments are performed under ambient conditions in downward spread configuration for a wide range of thicknesses (2 mm to 24 mm) for flat samples of Poly-Methyl Methacrylate (PMMA). The samples are held by two ceramic plates in order to obtain a two-dimensional propagation that is independent on the sample width. By analyzing videos of the experiments, the instantaneous spread rate is obtained using a recently developed MATLAB based tool. The shape of the pyrolyzing fuel is carefully measured after extinguishing the flame during a steady propagation. The spread rate and the burn angle, which is defined as the angle subtended by the pyrolyzing surface with respect of the fuel surface, are correlated, producing an expression for the burning rate in terms of the burn angle and flame spread rate. As the fuel thickness is increased, the burn angle and burning rate decrease and reach asymptotic limits for thermally thick fuels, in analogy with the spread rate limit. The comparison with data from literature suggests that in the thick limit the value of mass flux for PMMA (about 10 g/m² s) tends to the one of non-spreading flames. The presented geometrical approach to study the downward spread problem avoids the use of the B number and local gradients in order to calculate the mass burning rate of the fuel.     

Long-term results of intrarenal surgery for branched calculi: is such surgery still valid?

OBJECTIVE: To evaluate whether intrarenal surgery for branched calculi remains valid in the light of current new techniques, e.g. percutaneous nephrolithotomy and extracorporeal shockwave lithotripsy. PATIENTS AND METHODS: Between January 1978 and October 1984, 44 patients (24 male and 20 female, mean age 42.5 years, range 14-66) underwent complex surgery for large stones, requiring opening of the renal pelvis and a transparenchymal approach to the calices; 47 renal units were operated in 49 procedures. The evaluation before surgery included creatinine and blood nitrogen levels, blood pressure measurement, urine culture, abdominal plain X-ray (44 patients), intravenous urography (42) and isotopic renography with renal scintigraphy (five). Renal lithiasis was categorized and all patients underwent extended pyelolithotomy with a transparenchymal approach, achieved by partial nephrectomy (six patients), radial paravascular nephrotomy (10), posterior lower nephrolithotomy (29), resection of the posterior segment (two), and posterior segmentotomy and reconstruction (2); 16 operations were performed under ischaemia. In October 1996, the patients were clinically evaluated by serum creatinine levels (42), urine cultures (42), abdominal plain X-ray (42), IVU (34), isotopic renography (eight), renal ultrasonography (eight) and blood pressure measurement (44). The mean follow-up was 14.8 years. RESULTS: The major postoperative complications were; residual stones (six patients), fistula with ureteric stenosis (one, with a permanent nephrostomy), toxic temporary hepatic failure (one), femoral arterial embolism (one, resolved using a Fogarty catheter) and recurrent large stones (two, operated 1 and 5 years later). From 1984 to 1996, 19 patients had recurrent stones and two underwent dialysis. In October 1996, the renal function of 47 renal units was stable or normal in 36 (77%), reduced in seven (15%) and lost in four (8%); 24 patients were hypertensive (12 preoperatively), nine have urinary tract infection, three are positive for hepatitis B or C virus, and lithiasis has recurred in 15 renal units. CONCLUSIONS: Intrarenal surgery, conducted using modern anatomical guidelines, was an effective treatment for renal branched stones. The long-term results are satisfactory after appropriate correction of the urinary tract, with the consequent prevention of stasis and chronic infection. The definitive comparison between surgical and combined endoscopic/extracorporeal methods will only become clear when there is a comparable follow-up. Currently, surgery remains preferable in patients with giant calculi, a small pelvis and prevalent calyceal development.     

Renal angiomyolipoma with extrarenal involvement--in vascular, lymph-node and perirenal tissue. Reports of four cases

Extrarenal involvement was found in four cases of renal angiomyolipoma. In one case the wall of the inferior right bronchial artery was infiltrated, lymph nodes were involved in two cases and the perirenal fat in one case. Extrarenal extension does not seem to alter the prognosis of renal angiomyolipoma. Expectant treatment of this rare condition therefore appears to be warranted.