Search

In this work, the exceptionally improved sensing capability of highly porous three-dimensional (3-D) hybrid ceramic networks toward reducing gases is demonstrated for the first time. The 3-D hybrid ceramic networks are based on doped metal oxides (MexOyand ZnxMe1–xOy, Me = Fe, Cu, Al) and alloyed zinc oxide tetrapods (ZnO-T) forming numerous junctions and heterojunctions. A change in morphology of the samples and formation of different complex microstructures is achieved by mixing the metallic (Fe, Cu, Al) microparticles with ZnO-T grown by the flame transport synthesis (FTS) in different weight ratios (ZnO-T:Me, e.g., 20:1) followed by subsequent thermal annealing in air. The gas sensing studies reveal the possibility to control and change/tune the selectivity of the materials, depending on the elemental content ratio and the type of added metal oxide in the 3-D ZnO-T hybrid networks. While pristine ZnO-T networks showed a good response to H2gas, a change/tune in selectivity to ethanol vapor with a decrease in optimal operating temperature was observed in the networks hybridized with Fe-oxide and Cu-oxide. In the case of hybridization with ZnAl2O4, an improvement of H2gas response (to ∼7.5) was reached at lower doping concentrations (20:1), whereas the increase in concentration of ZnAl2O4(ZnO-T:Al, 10:1), the selectivity changes to methane CH4gas (response is about 28). Selectivity tuning to different gases is attributed to the catalytic properties of the metal oxides after hybridization, while the gas sensitivity improvement is mainly associated with additional modulation of the electrical resistance by the built-in potential barriers between n-nand n-pheterojunctions, during adsorption and desorption of gaseous species. Density functional theory based calculations provided the mechanistic insights into the interactions between different hybrid networks and gas molecules to support the experimentally observed results. The studied networked materials and sensor structures performances would provide particular advantages in the field of fundamental research, applied physics studies, and industrial and ecological applications.

Carotid plaque volume (CPV) can be measured by 3D ultrasound and may be a better predictor of stroke than stenosis, but analysis time limits clinical utility. This study tested the accuracy, reproducibility, and time saved of using an artificial intelligence (AI) derived semiautomatic software to measure CPV (“auto-CPV”).

A detailed spectroscopic analysis of Eu3+implanted and annealed GaN nanowires (NWs) and layers is presented by using temperature-dependent steady-state photoluminescence, room temperature photoluminescence excitation, and time-resolved photoluminescence. Independently of the used implantation angle and ion fluence, all the studied postimplant annealed samples evidence red 5D0→ 7FJluminescence transitions of the Eu3+(4f6) ions. One dominant Eu3+optical center was found for both GaN NWs and layers, together with the presence of different overlapped Eu3+minority optical centers. The thermal stability of the intra-4f6lines was found to be higher for the NWs where the red emission is observed with the naked eye even at room temperature. Besides the lanthanide emission, the photoluminescence spectra of the NWs and layers exhibit a broad yellow luminescence band (YL) differing slightly in the spectral shape and peak position in the different samples. While the YL in the layers is commonly ascribed to a free to bound (e-A) or donor–acceptor pair (DAP) transitions, the recombination kinetics of the YL in the NWs supports a model for a surface-mediated recombination process.

Abstract:: Giant cell arteritis most often affects the superficial temporal artery. Arterial territories such as the facial, carotid, myometrial and upper and lower limb arteries may be affected. In this paper we describe the case of a 52-year-old patient with upper and lower limb ischaemia who presented with grade III ischaemia in the left lower limb. Giant cell arteritis was diagnosed as responsible for the symptoms. After treatment with corticoids, an angiographic improvement was evidence after 2-year period. The low number of reported cases, the diverse symptoms and varied course make diagnosis of GCA difficult. Therefore, GCA must be taken into consideration in the ischaemia of inferior and superior limbs whether isolated or simultaneous.

The aim of this study was to evaluate our results in treatment and management of symptomatic hepatic venous malformations using transcatheter embolization therapy. From 1991 to 1997 five venous malformations were embolized in one man and four women ranging in age from 31 to 50 years. All patients presented nonspecific abdominal pain and were assessed in the general surgery unit. Percutaneous embolization was recommended. In all cases polyvinyl alcohol was used to embolize the afferent arterioles. Clinical and echographic control follow-up was carried out on an outpatient basis in our Vascular and Interventional Radiology Unit. Embolization was possible in all cases. No complications developed during the procedure, except in one case where the subject suffered a spasm of the hepatic artery. Mean follow-up time was 42 months (6–73 months). Four patients remained asymptomatic during the entire follow-up period, whereas one patient required reembolization. In our experience, transcatheter embolization of hepatic venous malformations is a noninvasive technique which requires few admissions and presents few complications. With further use, it could become the treatment of choice in symptomatic hepatic venous malformations as an alternative to surgery.

The kinetic parameters of acid and alkaline phosphatase activities were studied across afire-caused soil and vegetation chronosequence of semi-arid Mediterranean shrublands. All soils showed two peaks of optimal phosphatase activity, one in the acid range (pH 4) and another in the alkaline range (pH 11), but values of activity were considerably higher at the alkaline pH (about twice those corresponding to the acid range). For low substrate (p-nitrophenyl phosphate, PNPp) concentrations, mid-successional sites showed the highest phosphatase activity values within the sere. However, for substrate concentrations near saturation, a pattern of increasing phosphatase activity with increasing succesional age was apparent. In most cases, phosphatase activity, both in the acid and alkaline range, followed Michaelis-Menten kinetics. However, more complex kinetics, for instance competitive inhibition kinetic, were also observed in samples collected at the most eroded and recently burned sites. Substrate (PNPp) affinity of acid phosphatases significantly increased along the sere (Km values decreased). Values of Vmax did not show any consistent trend. The Km values of acid phosphatase were more highly correlated with soil phosphorus fractions than Km values of alkaline phosphatase. Conversely, correlations between K”; values and soil properties such as the ratio of oxidizable organic carbon to total nitrogen (Co/Nt) and organic carbon concentrations were strongest for alkaline phosphatases.

A digital image network has been installed at the Department of Radiology of the University of Santiago de Compostela, Spain, to create a ‘limited’ Picture Archiving and Communication System (PACS). This experience is being dedicated to address problems associated with digital techniques in a research environment. The backbone of the system is a multiprotocol ethernet network. Attached to the network are a number of advanced devices such as DEC VAX and UNIX workstations. Currently, a high resolution film digitizer and a laser printer are under evaluation for radiologic image research. During a period of nine years, 1987 to 1995, experimental and clinical trials have been conducted on different film based digital radiography apparatus primarily dedicated to chest and breast imaging. Several research projects have been completed. In this paper we describe the results of these investigations and discuss the advantages and disadvantages of this digital technique. The results of the different completed studies will be presented separately. A description of the physical characteristics of the limited PACS system dedicated to a research environment will serve as background.

Transcatheter embolization has proved to be an effective treatment for patients presenting with pelvic haemorrhage. Superselective catheterization with microcatheters facilitates the approach to the bleeding vessel and enables safer and more effective embolization. A 45-year-old man was admitted to hospital after blunt trauma to the left gluteal region. He complained of a painful enlarging mass in the left gluteal region. Radiography of the pelvis revealed absence of fracture. Selective angiography displayed significant extravasation from the left superior gluteal artery. Embolization was performed. The patient was discharged 2 days after admission with a resolving left gluteal haematoma.

The action of atebrin on purified adenosine triphosphatase (ATPase) from Micrococcus lysodeikticus was studied as well as on the membrane-bound and soluble ATPases from Escherichia coli and Bacillus megaterium. Atebrin inhibited the Ca(2+)-dependent activity of all these enzymes, and the inhibition was reversed by an excess of Ca(2+) ions. Kinetic studies carried out with the purified enzyme from M. lysodeikticus showed that the inhibition by atebrin was strongly cooperative, suggesting the complex nature of the process. On the other hand, atebrin stimulated the Mg(2+)ATPase activity of the M. lysodeikticus enzyme, displacing its adenosine 5'-triphosphate (ATP)/Mg(2+) optimum ratios, but inhibited the Mg(2+)-ATPase activity of E. coli provided that ATP was in excess over Mg(2+), i.e., that the ATP/Mg(2+) ratio was higher than its optimum. These results suggest that divalent cations influence the bacterial ATPases in different ways depending on the type of divalent ion and/or enzyme. The effect of atebrin on bacterial ATPases may reflect those differences, and its complex mechanism of action might be related to the existence of more than one site for divalent cations and/or distinct conformational states in these enzymes.

The effect of fire on ash deposition, litter ignition, and short-term changes in soil nutrient availability and erosion losses was studied after prescribed burning of a semiarid, gorse-scrubland ecosystem of SE Spain. Ash deposition added important amounts of P and cations but negligible amounts of N to the soil. The water-soluble fraction was only 3% for P added in ash but represented 20-60% for cations (Ca, K, Na). On a weight per area basis, 63% of the litter mass and 43% of the litter total N pool were lost by ignition during the fire. However, no significant changes were found for litter P and cations. Litter C/N, C/P, and N/P ratios significantly decreased. A sharp increase in the concentrations of labile P fractions and exchangeable cations was found in surface soils immediately after the fire. However, this fertilization effect lasted only a few weeks at most. Soil total and mineral N showed no significant differences immediately after the fire. Following the first important rain, nitrate concentrations increased sharply from 5 to above 20 μg NO3--N g-1 throughout a 3-month sampling period; whereas NH4+ concentrations decreased. Total erosion losses during that period were significantly higher in the burned and the clipped plots (734 and 845 kg ha-1, respectively) than in the control plot (46 kg ha-1). Erosion debris leaving the burned plot showed the highest nutrient concentrations shortly after the fire, particularly for total and water-soluble P. Such high initial concentrations tended to decrease progressively until they ranked with those found in the clipped plot for equivalent sampling periods. Total nutrient erosion losses from the clipped and burned plots were up to 1 order of magnitude higher than those from the control plot. Although total mass losses were higher after clipping, erosion removed 20% more N and 60% more P from the burned than from the clipped plot, which relates to the higher nutrient concentrations in debris originated at the burned plot. Data strongly suggest the nonconservative character of fire as a mineralizing agent in these steep, semiarid, oligotrophic ecosystems, and point out the risk of soil fertility depletion and desertification that high fire frequency imposes onto these areas.

Chemical properties and nutrient availability were measured in soil profiles of fire-prone, semiarid, Mediterranean-type shrublands in Sierra de Almijara (SE Spain). The area is steep and has a xeric moisture regime. In such conditions, soils developed on kakiritized (sugarlike microstructure) dolomitic marble have distinctive features such as a very coarse texture, extremely high carbonate content, and low nutrient availability. These soils support site-specific shrubland communities with many dolomitophile plant endemisms. During the last decades, the area has been subjected to a high fire frequency and intensive erosion, causing deforestation and soil degradation. To assess the problem, we chose a four-stage chronosequence representative of these changes, which included examples ranging from a long-unburned, dense, mature garigue stand, to an open, frequently burned, regenerating, gorse scrubland. The linear increase in the fire frequency along the chronosequence was associated to a sharp depletion of soil-available nutrients, namely, exchangeable cations, extractable mineral N, and especially NaHCO3-extractable inorganic P. The NH4+/NO3- ratio decreased through the sequence. Organic matter contents were >10%, and total N concentrations were >4mg N g-1 in surface soils of the long-unburned garigue site, which contrasted with values of <4% and 1 mg N g-1, respectively, in the most frequently burned, regenerating scrubland site. This decline of available nutrients is related to the slow recovery of the original garigue vegetation, or even substitution by other more degraded vegetation formations, that is observed in eroded sites, as well as with the lack of successful reforestation programs currently under way at the study site.

We report the endoluminal treatment of a para-anastomotic aneurysm with an endovascular stent-graft. A straight stent graft was inserted through the femoral artery into the abdominal aorta. The angiogram performed after the procedure showed total exclusion of the aneurysm. The patient has been asymptomatic for a 2 year follow-up period. We consider that this is a feasible technique in patients with high-risk for surgery, but more experience is required to evaluate the efficacy of the procedure.

Behcet's disease affects mainly male patients aged 11-30 years. It can affect any type of artery or vein. Pulmonary disease is produced in 5% of cases, manifesting as thromboembolism, heart attack and aneurysm formation. A pulmonary haemorrhage from a pulmonary aneurysm is described in a 34-year-old patient who was treated with percutaneous embolization after surgery.

Background: Quantitation of Der 1 and Der 2 in dust samples by specific monoclonal antibodies is a method used increasingly to evaluate mite allergen exposure. The level of Der 1 has been proposed as a risk factor for sensitization. Aim: We report a drastic decrease in the Der 1/Der 2 ratio when dust samples are collected in bakeries. Methods: Wheat flour and purified mites were extracted simultaneously; levels of Der p 1 and Der p 2 and cysteine protease activity were determined by ELISA and inhibition experiments. Results: High titers of Der 2, but only trace amounts of Der p 1, were detected in dust samples collected from bakeries. Both the level and proteolytic activity of Der p 1 appeared greatly decreased when mites and wheat flour were coextracted. Conclusions: Group 1 protein was found to be masked by flour components, resulting in an underestimation of the mite content in bakery dust. This problem was not found for group 2 allergen.

ZnO nanorod arrays have been grown by potentiostatic pulse electrodeposition between a reduction potential and a “rest” potential. The effect of the duty cycle and pulse frequency as well as the heat-treatment in air on the properties of the electrodeposits has been studied. Surface morphology, structural, optical and electrical properties were evaluated. Absorption spectra reveal a high energy bandgap Burstein-Moss shift for the as-grown nanorods, in line with the donor density (1.1 × 1019and 9.5 × 1019cm−3) determined from electrochemical impedance spectroscopy. After annealing, the carrier concentration decreases to 1017―1018cm−3, which is accompanied by an increase of the optical quality of the samples, assessed by the narrowing of the full width at half maximum of the near band edge recombination and steeper absorption at ∼3.3 eV. The donor density and the flatband potential are dependent of the applied duty cycle and pulse frequency. All the analyzed samples evidence deep broad emission bands in the visible region, whose intensity is enhanced after annealing. The defect luminescence is due to an overlap of emitting centers in the red, yellow and green spectral regions, as evidenced and discussed by comparing the steady-state and transient spectroscopies.

J Allergy Clin Immunol 1997;99:577-8.