Influence of natural seawater variables on the corrosion behaviour of aluminium-magnesium alloy.

Corrosion is an important issue for alloys in natural seawater, where microorganisms can accelerate or mitigate corrosion. Al-Mg alloys are used for marine activities and various associated technologies. Here, the behaviour of AA5083 alloy was investigated in natural seawater with marine exposure lasting up to 50 days and detailing the first 8 days in two experimental series. Experimental work was carried out, including semi-field tests in natural seawater (biotic conditions) compared with abiotic conditions. The open circuit potential (OCP) measurements, during the immersion time, exhibited significantly different behaviours: an OCP downward displacement occurred under abiotic conditions, while, in biotic conditions OCP remained generally stable since the beginning of the immersion, revealing an inhibiting effect of the biological activity on the Al-Mg corrosion. This was accompanied by different surface modifications under biotic conditions: surface and cross-section characterization, performed by scanning electron microscopy with energy dispersive X-ray spectroscopy, showed less corrosion developed on the surface after 8-day immersion and formation of a protective layer during 50-day immersion. The present study shows that marine biological activity positively influences the Al alloy corrosion process, with surface modifications resulting in a protective effect counteracting the aggressiveness of chloride ions.

Process of ammonia removal from anaerobic digestion and associated ammonium sulphate production: Pilot plant demonstration.

A process for the continuous extraction of ammonia from anaerobic digesters is proposed. In this process, a portion of the sludge treated in the digesters is continuously withdrawn and transferred to a thin film evaporator (TFE) unit, where the ammonia is stripped through a biogas stream. The ammonia-rich biogas is treated with a sulfuric acid/water solution in a reactive absorption unit, with production of ammonium sulphate. The chemistry of a CH4/CO2/NH3 gas phase in thermodynamic equilibrium with a liquid sulfuric acid/water solution is investigated theoretically, with focus on the simultaneous absorption of CO2 and NH3 into the liquid phase. Pilot plant experimental data confirm the theoretical results. Further pilot plant experimental results obtained during on-off cycles of the stripping equipment demonstrate that, when the TFE unit is off, ammonia concentration in the digestate rises quickly, while, when the stripping equipment is turned on again, ammonia concentration drops down. On average, during the 180 days of pilot plant experimentation, 4.1 g N-NH4 per kg of sludge fed to the digester, i.e. 19.3 g N-NH4 per kg of total solids (TS) fed to the digester, are stripped from digestate and recovered as ammonium sulphate, demonstrating the feasibility of the proposed concept.

An assessment of electric vehicles: technology, infrastructure requirements, greenhouse-gas emissions, petroleum use, material use, lifetime cost, consumer acceptance and policy initiatives.

Concerns about climate change, urban air pollution and dependence on unstable and expensive supplies of foreign oil have led policy-makers and researchers to investigate alternatives to conventional petroleum-fuelled internal-combustion-engine vehicles in transportation. Because vehicles that get some or all of their power from an electric drivetrain can have low or even zero emissions of greenhouse gases (GHGs) and urban air pollutants, and can consume little or no petroleum, there is considerable interest in developing and evaluating advanced electric vehicles (EVs), including pure battery-electric vehicles, plug-in hybrid electric vehicles and hydrogen fuel-cell electric vehicles. To help researchers and policy-makers assess the potential of EVs to mitigate climate change and reduce petroleum use, this paper discusses the technology of EVs, the infrastructure needed for their development, impacts on emissions of GHGs, petroleum use, materials use, lifetime costs, consumer acceptance and policy considerations.

Comparison of cyclosporine concentrations 2 hours post-dose determined using 3 different methods and trough level in pediatric renal transplantation.

Immunosuppression has been one of the great challenges in pediatric recipients of kidney allografts. Cyclosporine (CsA) has evolved during the past 25 years of transplantation. It requires frequent blood level monitoring because of its narrow therapeutic window and interpatient and intrapatient variability. Neoral (Novartis) is no exception. Ideally, monitoring of blood levels should also include determination of the area under the time-concentration curve (AUC) to better target the therapeutic window, thus avoiding underdosing or overdosing, especially in pediatric patients. A single blood concentration measurement 2 hours after Neoral administration (C2) has been shown to be a more for accurate predictor of drug exposure than trough levels (C0). Therefore, its use may lead to reduction in the incidence and severity of cellular rejection and of CsA toxicity. Some studies have shown that the metabolites/CsA ratio is substantially lower using C2 than C0, however, the between-assay differences for C2 monitoring have not been considered. The purpose of this study was to evaluate CsA C0 and C2 levels, determined using monoclonal fluorescence polarization immunoassay (FPIA)/TDx and enzyme multiplied immunoassay (EMIT). CsA levels were determined using a radioimmunoassay (RIA) in 30 pediatric transplant recipients with stable renal function within 42.7 mean months follow-up. Mean age was 13.4 years; 15 children were girls; 23 patients were recipients of cadaveric kidneys. The mean CsA microemulsion dose was 5.7 mg/kg/d. The 3 methods showed a high correlation between C0 and C2 (r > or = 0.97). A linear regression slope was significantly higher for C0 than C2 (P < .001). The CsA concentrations both at C0 and C2 were significantly higher with FPIA than with RIA (P < .009) but no differences were found for EMITT (P = .2). The mean C0 level for FPIA was 22% and 26% higher than RIA and EMIT, respectively. The mean C2, for FPIA was 7% and 12% higher than RIA and EMIT, respectively. In conclusion, CsA levels determined using RIA or EMIT are better than using FPIA/Tx; also, C2 CsA levels are more accurate than C0 in pediatric transplantation patients.

[Vascular accesses for chronic hemodialysis in children]. / Accesos vasculares para hemodiálisis crónica en niños.

BACKGROUND: The success of a chronic hemodialysis program depends on a good vascular access. AIM: To evaluate the experience with vascular accesses for chronic hemodialysis in pediatric patients. PATIENTS AND METHODS: One hundred fifty-one vascular accesses used in 60 pediatric patients (33 female) coming from 2 hemodialysis (HD) centers were analyzed. RESULTS: The average age of admission to the hemodialysis program was 10 years old (range 1.8-15). Forty percent of accesses were internal arterio-venous fistulae (AVF), 58% were central venous catheters and 2% were grafts. Twenty four patients required a central venous catheter from the beginning since they required immediate dialysis. Twenty patients began dialysis with a permeable AVF and never required another vascular access. Eight small children used a central catheter as the only vascular access and 32 patients required both types of vascular accesses. Eighty-seven catheters were used in 34 patients, of which 77 were temporary and 10 permanent. Seventeen patients needed only one catheter and one girl required 15 catheters. The average life span for AVF was 524 days (20-1277), for temporary catheters 34 days (1-76) and for permanent catheters 73 days (9-147). Two years survival of AVF was 95%. One month survival for subclavian and jugular catheters was 50%. Fifty-six percent of AVF had no complications, 12 failed due to insufficient flow and 24% had a complication. Of the 87 catheters placed, 75% had complications and 22 were electively removed. CONCLUSIONS: Arteriovenous fistula is the vascular access of choice for hemodialysis in pediatric patients. Central venous catheters can become an essential access, specially in small children.

[Idiopathic hypercalciuria. Differential diagnosis]. / Hipercalciuria idiopática. Diagnóstico diferencial.

In 50 children with hematuria or urolithiasis and idiopathic hypercalciuria, and in 15 control children, urinary calcium/creatinine concentration rates were measured after fasting and after calcium loading. Patients were classified into two groups depending on the results of an orally administered calcium loading test. Children were considered to have absorptive hypercalciuria (42%) when they had low fasting urinary calcium/creatinine concentration ratio (less than 0.21), and a large increase of this index after calcium administration (greater than 0.28). Patients were labeled as renal hypercalciuria (32%) if they had high fasting urinary calcium/creatinine concentration ratio (greater than 0.21), and variable increases of it after calcium overload. A third group of children (26%), were not classifiable by means of this test. Our data support the contention that this simple ambulatory test is very useful in the diagnostic workup of idiopathic hypercalciuria.

[Chronic hemodialysis in children]. / Hemodiálisis crónica en niños.

The clinical features of eight patients, four females, aged 4 to 15 years under chronic hemodialysis for terminal renal failure (creatinine clearance 10 ml.min.1,73 m2 or less) are reported. Initial diseases were Alport syndrome, systemic lupus erythematosus, chronic glomerulonephritis (n = 2), bilateral polycystic kidney, prune belly syndrome and reflux nephropathy (n = 2). Distal vascular approach by means of arteriovenous fistulas was preferred for these patients and the kinetic urea model was used to evaluate the performance of the procedure. Patients required nine to twelve hours of hemodialysis per week for optimal results. Mean weight decreases of 1 to 3 kg and reductions in blood urea nitrogen and serum potassium of 40 mg.dl and 2,5 mEq.1, respectively, were observed. The main complications of hemodialysis were the disequilibrium syndrome, infections at the site of insertion of the arteriovenous fistulae and congestive heart failure. Three patients were submitted to renal transplantation with live donors homografts: one died and the other two remain alive but under chronic hemodialysis. Five children are attending school regularly, and two of them are waiting a kidney donor for transplantation. Despite encouraging results chronic hemodialysis in children constitutes only primary supportive therapy prior to renal transplantation.

The use of oral hydration in the treatment of children with acute diarrhea in primary care.

The use of oral rehydration solutions (ORSs) for treating children with diarrhea is spreading in hospitals in Chile, but it has not yet been incorporated into routine primary care programs. We sequentially compared the effectiveness of an ORS, with 60 mmol/L of Na+, with the standard treatment for diarrhea used in primary care centers, in a study with 285 diarrheal children under 2 years of age who consulted a health center in a low-income periurban neighborhood of Santiago. When compared with the control group, the patients treated with ORS showed a significantly higher percentage weight gain in the first few days after treatment was begun, required fewer medical visits for follow-up treatment at other facilities (8.4 vs. 15.5%; p less than 0.05), and experienced fewer episodes of subsequent clinical dehydration that needed rehydration (oral or intravenous) in emergency services (2.8 vs. 10.6%; p less than 0.01). In addition, there were no metabolic complications in either group. Our results reinforce the feasibility, efficaciousness, and safety of programs that use ORS at the primary care level and indicate that this is an effective method of preventing metabolic complications and reducing hospitalizations of children with acute diarrhea.

PIP: The use of oral rehydration solution (ORS) for treating children with diarrhea is spreading in hospitals in Chile, but it has not yet been incorporated into routine primary care programs. The authors sequentially compared the effectiveness of an ORS with 60 mmol/L of Na+ with the standard treatment for diarrhea used in primary care centers. This was done with 285 diarrheal children under age 2 who consulted a health center in a low-income periurban neighborhood of Santiago. When compared with the control group, the patients treated with ORS showed a significantly higher % of weight gain in the 1st few days after treatment was begun, required fewer medical visits for follow-up treatment at other facilities (8.4 vs 15.5%; p0.05), and experienced fewer episodes of subsequent clinical dehydration that required rehydration (oral or intravenous) in emergency services (2.8 vs 10.6%; p0.01). In addition, there were no metabolic complications in either group. These results reinforce the feasibility, efficaciousness, and safety of programs that use ORS at the primary care level and indicate that this is an effective method of preventing metabolic complications and reducing hospitalizations of children with acute diarrhea.

Intestinal leiomyosarcoma in childhood: report of two cases.

Two girls, 5 and 8 years old, with a leiomyosarcoma of the rectosigmoid and ileum, respectively, were treated at Hospital Luis Calvo Mackenna. In each case, a segmental resection with primary anastomosis was done. After the initial surgery, neither girl has received further treatment for the tumor. To date the two patients remain clinically well and apparently tumor free.

Etiologia de otitis media aguda purulenta en lactantes. / Etiology of acute suppurative otitis media in infants

Se estudiaran 41 lactantes con el diagnostico de otitis media aguda. Streptococcus pneumoniae fue el agente mas frecuente aislado (48,8%). Haemophilus influenzae se aislo como segunda etilogia. La parecentesis esta indicada en casos muy especificos y el pediatra general puede prescindir de ella en la mayoria de ellos. Conociendo las posibilidades etiologicas del cuadro se puede elegir una terapia adecuada

Insomnia in the elderly: treatment with flurazepam hydrochloride.

Under sleep-laboratory control, the efficacy of flurazepam hydrochloride (15 mg) was evaluated in 6 women (age range, 67-82 years) with objectively verified insomnia. A 15-night, single-blind, crossover procedure was followed. Sleep records obtained during 3 placebo-baseline nights, 7 consecutive flurazepam nights, and 3 placebo-withdrawal nights were evaluated by means of electroencephalographic, electro-oculographic, and electromyographic criteria. A statistically significant reduction in sleep latency and total awake time and a corresponding increase in total sleep time (P less than 0.05) were demonstrated during the active drug period. No evidence of diminishing effectiveness was observed during the 7 days of drug administration. For the rapid-eye-movement (REM) stage, a significant decrease (P less than 0.05) in mean REM percent was noted during the drug period despite an increase in mean absolute REM time. No REM rebound occurred upon drug withdrawal. There were no significant changes in mean percentages for stages 3 and 4 during the drug period and the withdrawal period. Adverse reactions were rare (chiefly some daytime drowsiness in 2 subjects).

The Skylab sleep monitoring experiment: methodology and initial results.

The sleep monitoring experiment permitted an objective evaluation of sleep characteristics during the first two manned Skylab flights. Hardware located onboard the spacecraft accomplished data acquisition, analysis, and preservation, thereby permitting near-real-time evaluation of sleep during the flights and more detailed postmission analysis. The crewman studied during the 28-Day Mission showed some decrease in total sleep time an increase in the percentage of Stage 4 sleep, while the subject in the 59-Day Mission exhibited little change in total sleep time and a small decrease in Stage 4 and REM sleep. Some disruption of sleep characteristics was seen in the final days of both missions, and both subjects exhibited decreases in REM-onset latency in the immediate postflight period. The relatively minor changes seen were not of the type nor magnitude which might be expected to be associated with significant degradation of performance capability.