Dysprosium doped copper oxide (Cu1-xDyxO) nanoparticles enabled bifunctional electrode for overall water splitting

The production of hydrogen, a favourable alternative to an unsustainable fossil fuel remains as a significant hurdle with the pertaining challenge in the design of proficient, highly productive and sustainable electrocatalyst for both oxygen evolution reaction (OER) and hydrogen evolution reaction (HER). Herein, the dysprosium (Dy) doped copper oxide (Cu_1-xDy_xO) nanoparticles were synthesized via solution combustion technique and utilized as a non-noble metal based bi-functional electrocatalyst for overall water splitting. Due to the improved surface to volume ratio and conductivity, the optimized Cu_1-xDy_xO (x = 0.01, 0.02) electrocatalysts exhibited impressive HER and OER performance respectively in 1 M KOH delivering a current density of 10 mAcm^?2 at a potential of ?0.18 V vs RHE for HER and 1.53 V vs RHE for OER. Moreover, the Dy doped CuO electrocatalyst used as a bi-functional catalyst for overall water splitting achieved a potential of 1.56 V at a current density 10 mAcm^?2 and relatively high current density of 66 mAcm^?2 at a peak potential of 2 V. A long term stability of 24 h was achieved for a cell voltage of 2.2 V at a constant current density of 30 mAcm^?2 with only 10% of the initial current loss. This showcases the accumulative opportunity of dysprosium as a dopant in CuO nanoparticles for fabricating a highly effective and low-cost bi-functional electrocatalyst for overall water splitting.     

Optimization of flow in additively manufactured porous columns with graded permeability

Chemical engineering systems often involve a functional porous medium, such as in catalyzed reactive flows, fluid purifiers, and chromatographic separations. Ideally, the flow rates throughout the porous medium are uniform, and all portions of the medium contribute efficiently to its function. The permeability is a property of a porous medium that depends on pore geometry and relates flow rate to pressure drop. Additive manufacturing techniques raise the possibilities that permeability can be arbitrarily specified in three dimensions, and that a broader range of permeabilities can be achieved than by traditional manufacturing methods. Using numerical optimization methods, we show that designs with spatially varying permeability can achieve greater flow uniformity than designs with uniform permeability. We consider geometries involving hemispherical regions that distribute flow, as in many glass chromatography columns. By several measures, significant improvements in flow uniformity can be obtained by modifying permeability only near the inlet and outlet.     

Transjugular intrahepatic portosystemic shunts (TIPS) in children

The transjugular intrahepatic portosystemic shunt procedure is an accepted treatment for adults with complications of portal hypertension. We performed a retrospective review of all pediatric TIPS placements performed at the University of California, San Francisco between 1990 and 1996. Twelve procedures were attempted in nine children, with a mean age (+/- SD) of 9.4 +/- 3.9 years (range, 5 to 15 years) and a mean weight of 31 +/- 18 kg (range, 16 to 70 kg). The indications for TIPS placement were portal hypertension complicated by chronic variceal hemorrhage not controlled with sclerotherapy (n = 7) and hypersplenism with thrombocytopenia (n = 2). TIPS placement was successfully completed initially in seven of nine (78%) patients. Unfavorable vascular anatomy was the cause of failure in two cases. The seven patients who underwent successful TIPS placement were followed up for an average of 136 days (range, 1 to 800 days); two still have patent shunts, three underwent liver transplantation, one had a splenorenal shunt after stenosis, and one died of underlying liver disease. Variceal bleeding was controlled in four of five patients who successfully underwent TIPS placement. Shunt occlusion occurred in four patients; patency was restored by transjugular shunt revision in three, and a splenorenal shunt was performed in one.     

Modeling ion implantation of HgCdTe

Ion implantation of boron is used to create n on p photodiodes in vacancy-doped mercury cadmium telluride (MC.T). The junction is formed by Hg interstitials from the implant damage region diffusing into the MC.T and annihilating Hg vacancies. The resultant doping profile is n⁺/n^-/p, where the n⁺ region is near the surface and roughly coincides with the implant damage, the n^- region is where Hg vacancies have been annihilated revealing a residual grown-in donor, and the p region remains doped by Hg vacancy double acceptors. We have recently developed a new process modeling tool for simulating junction formation in MC.T by ion implantation. The interstitial source in the damage region is represented by stored interstitials whose distribution depends on the implant dose. These interstitials are released into the bulk at a constant, user defined rate. Once released, they diffuse away from the damage region and annihilate any Hg vacancies they encounter. In this paper, we present results of simulations using this tool and show how it can be used to quantitatively analyze the effects of variations in processing conditions, including implant dose, annealing temperature, and doping background.     

Influence of caloric intake on aging and on the response to stressors

Reducing the food intake of rodents to well below that of ad libitum fed animals increases the life span. This action, which gerontologists often refer to as the antiaging action of dietary restriction (DR), is due to the slowing of the aging processes. DR also maintains most physiological processes in a youthful state and delays the occurrence and/or slows the progression of age-associated disease processes. This antiaging action of DR results from the reduced intake of calories. Reduction of the body fat content does not play a causal role in the antiaging action of DR, nor does reduction in the metabolic rate. Alterations in the characteristics of carbohydrate metabolism and of oxidative metabolism in response to DR have been found that are of such a nature that they could, at least in part, underlie the antiaging action. Several theories have recently been proposed in regard to the mechanisms responsible for the antiaging action of DR, but none has been tested by rigorously designed studies. Of these theories, the one that seems most promising is based on the fact that DR protects rats and mice of all ages against the damaging actions of acute stressors. This protective action against stressors may play a major role in the antiaging action of DR.     

Recurrent erosion after photorefractive keratectomy

Recurrent erosion of the corneal epithelium has been treated successfully by phototherapeutic keratectomy when convention therapy has failed. We present a case of recurrent corneal erosion occurring 1 year after photorefractive keratectomy in a 55-year-old myopic woman. No corneal abnormalities were previously identified in either the affected or the fellow eye. This case demonstrates the potential for ineffective healing of the corneal epithelial basement membrane complex after excimer laser photorefractive keratectomy.     

Recurrent Epstein-Barr virus-associated lesions in organ transplant recipients

This paper discusses the problem of violence and its expression upon mortality due to external causes. A few indicators are offered, which have been worked upon it to emphasise the importance of the theme. In a general way, the study demonstrates violent death has had its magnitude increased along the years, not only throughout Latin America but also in Brazil and in Santa Catarina.     

Time-frequency plane Wiener filtering of the high-resolution ECG: background and time-frequency representations

The diel 'activity', i.e. availability, of Ixodes ricinus larvae, nymphs and adults was investigated in a meadow and a forest habitat near Stockholm during 1991-1993. Generally, the immature ticks were more prevalent in the forest than in the meadow. In the meadow, the mean larval and adult numbers varied significantly between 4 h time intervals with the peak activity from 2300 to 0300 h. In the forest, the tick numbers did not differ significantly between the time intervals. The association of the tick activity with certain meteorological variables was strongest in the meadow, where the mean numbers of all tick stages were negatively correlated with the temperature. The relative humidity was positively correlated only with the mean numbers of larvae. In contrast, the larval activity in the forest was positively and negatively correlated with the temperature and relative humidity, respectively, while the nymphal and adult activity showed no association with these climatic variables. The impact of the host activity on the tick diel activity is also discussed.     

Professor Gerard Jonderko--life and achievements of the honorary member of the Polish Society of Internal Medicine

Between February 1995 to August 1997, 120 patients underwent elective stent implantation for isolated proximal left anterior descending coronary artery stenosis. Their age ranged from 31 to 72 years (mean: 50.8 +/- 10.2) and the majority (89%) were males. All patients had angina, documented myocardial ischemia or both and 70 percent or more luminal diameter stenosis in the proximal left anterior descending before the origin of any branch. Majority (62.5%) of the treated lesions were type A. Successful deployment of the stent at the target site was achieved in all patients without any major in-hospital complications, including myocardial infarction, emergency bypass graft surgery or death. Clinical follow-up, ranging from 6 to 31 months (mean: 18.5 +/- 8.1, median: 20), was available in 87 out of 92 (94.5%) eligible patients who had completed at least six months after the procedure. Freedom from angina, myocardial infarction, target lesion revascularization and death was observed in 90.8, 100, 95.4 and 97.7 percent of patients, respectively. By the Kaplan-Meier estimate, an event-free survival (absence of death, myocardial infarction, recurrence of angina or revascularization) was 95.4 percent at six months, 89.5 percent at 12 and 18 months and 82.7 percent at 24 to 31 months of follow-up. Only 10 (11.5%) patients developed any event and TLR was required in 4.6 percent of patients. In conclusion, elective stenting for isolated proximal left anterior descending stenosis can be achieved safely and successfully in all patients without any adverse in-hospital events. This modality of treatment also provides long-term benefits in terms of reduction in major cardiovascular events and need for subsequent revascularization.     

Chronic fluoride exposure does not cause detrimental, extraskeletal effects in nutritionally deficient rats

On the basis of observations that endemic fluorosis occurs more often in malnourished populations, a series of studies tested the hypothesis that deficient dietary intake of calcium, protein or energy affects fluoride metabolism so that the margin of safe fluoride exposure may be reduced. The objective of the investigation was to determine whether changes in fluoride metabolism in nutritionally deficient rats resulted in manifestation of any extraskeletal toxic fluoride effects not observed in healthy animals. This investigation included two studies, one that monitored the effect of calcium deficiency on the effects of chronic fluoride exposure, and a second study that observed fluoride effects in rats that were deficient either in protein or in energy and total nutrient intake. Control and experimental rats received drinking water containing 0, 0.26 (5), 0.79 (15) or 2.63 (50) mmol fluoride/L (mg/L) for 16 or 48 wk. Control rats were fed optimal diets and experimental rats were fed diets deficient in calcium (Study 1) or protein (Study 2). An additional group of experimental rats (Study 2) was provided with a restricted amount of diet; thus these rats were deficient in energy and total nutrient intake. The intake, excretion and retention of fluoride were monitored; after the rats were killed, tissue fluoride levels and biochemical markers of tissue function were analyzed. Bone marrow cells were harvested from some of the rats, after 48 wk of treatment, for determining the frequency of sister chromatid exchange, a marker of genetic damage. Although there were significant differences among fluoride treatment groups in fluoride excretion and retention that resulted in significantly greater fluoride levels in tissues of the experimental rats, we were unable to detect any harmful, extraskeletal biochemical, physiologic or genetic effects of fluoride in the nutritionally deficient rats.