Visible light activated SnO2:Dy thin films for the photocatalytic degradation of methylene blue.

This paper explores the impact of dysprosium (Dy) doping on structural, optical, and photocatalytic properties of tin oxide (SnO2) thin films fabricated via spray pyrolysis. Dysprosium doping levels ranged from 0 to 7 at%, and films were grown on glass substrates at 350 °C. X-ray diffraction (XRD) analysis revealed an increase in crystallite size with Dy doping, signifying improved crystalline quality. Simultaneously, dislocation density and strain decreased, indicating enhanced film quality. Texture coefficient (Tchkl) results showed a predominant crystal orientation along the (110) plane due to Dy doping. Optical band gap energy (Eg) decreased with Dy doping up to 5%. Urbach energy increased with Dy doping, suggesting atomic structural flaws and defects. Scanning electron microscopy (SEM) analysis revealed the presence of numerous micro-aggregates on the film's surface. Notably, the density of these micro-aggregates increased proportionally with higher Dy doping levels, particularly emphasizing the pronounced effect observed in SnO2:Dy 5% thin films. These findings underscore the potential of Dy-doped SnO2 thin films for advanced photocatalytic applications, with SnO2:Dy 5% exhibiting favorable properties and demonstrating a 90.99% degradation efficiency in three hours under solar irradiation.

Physical and photocatalytic properties of sprayed Dy doped ZnO thin films under sunlight irradiation for degrading methylene blue.

Dysprosium-doped zinc oxide (ZnO) thin films have been prepared through spray pyrolysis onto glass substrates. Cross-sections of the deposited thin films were assessed through Scanning Electron Microscopy (SEM), showing thicknesses between 200 and 300 nm. The thin film roughness was evaluated using the obtained images from the Atomic Force Microscope (AFM) micrographs. The crystallographic structure of the samples was analyzed by X-ray diffraction (XRD) revealing polycrystalline thin films. However, the slight shift towards a higher 2θ angle in Dy-doped ZnO films as compared to the pure ones indicates the incorporation of Dy3+ into the ZnO crystal lattice. The analysis of the oxidation state via X-ray photoelectron spectroscopy (XPS) confirms the incorporation of Dy ions in the ZnO matrix. Besides, UV-Vis-NIR spectrophotometry analysis and photoluminescence (PL) spectroscopy showed that bandgap energy values of ZnO decreased when dysprosium doping increased. Therefore, Dy doped ZnO thin films can be potentially used as a solar-light-driven photocatalyst. Among the different doping yields, the ZnO doped with 6% dysprosium provides the highest degradation rate for methylene blue (MB) under solar irradiation. Specifically, 9% of dye degradation was achieved under sunlight irradiation for 120 minutes.

Aerosol-Assisted CVD-Grown PdO Nanoparticle-Decorated Tungsten Oxide Nanoneedles Extremely Sensitive and Selective to Hydrogen.

We report for the first time the successful synthesis of palladium (Pd) nanoparticle (NP)-decorated tungsten trioxide (WO3) nanoneedles (NNs) via a two-step aerosol-assisted chemical vapor deposition approach. Morphological, structural, and elemental composition analysis revealed that a Pd(acac)2 precursor was very suitable to decorate WO3 NNs with uniform and well-dispersed PdO NPs. Gas-sensing results revealed that decoration with PdO NPs led to an ultrasensitive and selective hydrogen (H2) gas sensor (sensor response peaks at 1670 at 500 ppm of H2) with low operating temperature (150 °C). The response of decorated NNs is 755 times higher than that of bare WO3 NNs. Additionally, at a temperature near that of the ambient temperature (50 °C), the response of this sensor toward the same concentration of H2 was 23, which is higher than that of some promising sensors reported in the literature. Finally, humidity measurements showed that PdO/WO3 sensors displayed low-cross-sensitivity toward water vapor, compared to bare WO3 sensors. The addition of PdO NPs helps to minimize the effect of ambient humidity on the sensor response.

Carbon nanotubes randomly decorated with gold clusters: from nano2hybrid atomic structures to gas sensing prototypes.

Carbon nanotube surfaces, activated and randomly decorated with metal nanoclusters, have been studied in uniquely combined theoretical and experimental approaches as prototypes for molecular recognition. The key concept is to shape metallic clusters that donate or accept a fractional charge upon adsorption of a target molecule, and modify the electron transport in the nanotube. The present work focuses on a simple system, carbon nanotubes with gold clusters. The nature of the gold-nanotube interaction is studied using first-principles techniques. The numerical simulations predict the binding and diffusion energies of gold atoms at the tube surface, including realistic atomic models for defects potentially present at the nanotube surface. The atomic structure of the gold nanoclusters and their effect on the intrinsic electronic quantum transport properties of the nanotube are also predicted. Experimentally, multi-wall CNTs are decorated with gold clusters using (1) vacuum evaporation, after activation with an RF oxygen plasma and (2) colloid solution injected into an RF atmospheric plasma; the hybrid systems are accurately characterized using XPS and TEM techniques. The response of gas sensors based on these nano(2)hybrids is quantified for the detection of toxic species like NO(2), CO, C(2)H(5)OH and C(2)H(4).

Carbon nanotube-TiO(2) hybrid films for detecting traces of O(2).

Hybrid titania films have been prepared using an adapted sol-gel method for obtaining well-dispersed hydrogen plasma-treated multiwall carbon nanotubes in either pure titania or Nb-doped titania. The drop-coating method has been used to fabricate resistive oxygen sensors based on titania or on titania and carbon nanotube hybrids. Morphology and composition studies have revealed that the dispersion of low amounts of carbon nanotubes within the titania matrix does not significantly alter its crystallization behaviour. The gas sensitivity studies performed on the different samples have shown that the hybrid layers based on titania and carbon nanotubes possess an unprecedented responsiveness towards oxygen (i.e. more than four times higher than that shown by optimized Nb-doped TiO(2) films). Furthermore, hybrid sensors containing carbon nanotubes respond at significantly lower operating temperatures than their non-hybrid counterparts. These new hybrid sensors show a strong potential for monitoring traces of oxygen (i.e. ≤10 ppm) in a flow of CO(2), which is of interest for the beverage industry.

Use of a MS-electronic nose for prediction of early fungal spoilage of bakery products.

A MS-based electronic nose was used to detect fungal spoilage (measured as ergosterol concentration) in samples of bakery products. Bakery products were inoculated with different Eurotium, Aspergillus and Penicillium species, incubated in sealed vials and their headspace sampled after 2, 4 and 7 days. Once the headspace was sampled, ergosterol content was determined in each sample. Different electronic nose signals were recorded depending on incubation time. Both the e-nose signals and ergosterol levels were used to build models for prediction of ergosterol content using e-nose measurements. Accuracy on prediction of those models was between 87 and 96%, except for samples inoculated with Penicillium corylophilum where the best predictions only reached 46%.

Quantitative analysis of NO2 in the presence of CO using a single tungsten oxide semiconductor sensor and dynamic signal processing.

We demonstrate that NO2 can be quantitatively analysed in the presence of CO using a single tungsten oxide based resistive gas sensor. The working temperature of the sensor was modulated between 190 and 380 degrees C and its dynamic response to different concentrations of CO, NO2, and CO + NO2 mixtures was monitored. Either the fast Fourier transform (FFT) or the discrete wavelet transform (DWT) was used to extract important features from the sensor response. These features were then input to different (statistical and neural) pattern recognition methods. The species considered can be discriminated with a success rate higher than 90% using a Fuzzy ARTMAP or a radial basis function neural network. The concentrations of the gases studied can be accurately predicted, by using the DWT coupled to partial least squares (PLS) models. The correlation coefficients of the predicted versus real concentrations were 0.923, 0.870 and 0.866 for CO, NO2, and NO2 in CO + NO2 mixtures, respectively.

Changes in left ventricular filling pattern during dobutamine stress Doppler echocardiography.

AIMS: To study the left ventricular filling pattern during stress Doppler echocardiography and its utility in the detection of myocardial ischaemia. METHODS AND RESULTS: Fifty-seven consecutive patients underwent dobutamine stress echocardiography. The left ventricular filling pattern (E-wave velocity; A-wave velocity; E/A ratio; E-wave deceleration time) was analysed at baseline and at maximum heart rate reached. The percentage increase in these parameters from baseline to peak heart rate was also determined. Myocardial ischaemia (regional contractility worsening) was induced in 19 cases (ischaemic group) but not in 38 cases (non-ischaemic group). There were no differences between both groups at baseline. E-wave deceleration time decreased in the non-ischaemic group (197+/-63 vs. 167+/-65 ms, P=0.01) and increased in the ischaemic group (203+/-42 vs. 315+/-135 ms, P<0.0001). A percentage increase in E-wave deceleration time of >30% showed a positive predictive value of 93% and a negative predictive value of 86% for detecting ischaemia, and in the multivariate analysis it was the only Doppler parameter (P<0.0001) that predicted the induction of ischaemia. CONCLUSION: We conclude that myocardial ischaemia provokes an increase in E-wave deceleration time. Analysis of left ventricular filling could help in the identification of those cases which are positive for ischaemia.

[Seroepidemiology of hepatitis A virus infection in medical and nursing students. The role of vaccination]. / Seroepidemiología de la infección por el virus de la hepatitis A en estudiantes de medicina y enfermería. Papel de la vacunación.

BACKGROUND: Recent seroepidemiologic studies have demonstrated a decrease in the prevalence of hepatitis A virus infection (HAV) in relation with an improvement in hygienic conditions. The prevalence of anti-HAV in a group of health care students was studied and a vaccination program initiated in this collective. METHODS: Serum anti-HAV determination was performed by an enzymoimmunoanalysis method. A inactivated hepatitis A vaccine was administered. RESULTS: Only 18.5% of the subjects between 17-23 years-old presented anti-HAV antibodies. The prevalence of anti-HAV was related with age and the number of partners. All of the 129 immunized individuals responded to the HAV vaccine with protector antibody titles. CONCLUSION: The present study demonstrates the decrease in HAV infection among youths as well as the immunogenicity of the anti-hepatitis A vaccine.

[Prevalence of the use of urinary drainage systems in Spanish hospitals]. / Prevalencia de uso de los sistemas de drenaje urinario en los hospitales españoles. Grupo de Trabajo EPINE.

BACKGROUND: Urinary catheterization constitutes the main risk factor in urinary infections or nosocomial origin. The use of closed urinary drainage systems is fundamental to decrease this risk. The prevalence of the use of a urethral catheter as well as the proportion of closed type drainage systems in the Spanish medium was studied with the aim of improving the degree of the adoption of control measures for this type of infections. METHODS: The prevalence of patients submitted to urinary catheterization (distinguishing between open and closed systems) in an important sample of Spanish hospitals was determined from the data provided by the EPINE project (1990-1993). The evolution over 4 years in addition to distribution by hospitalization areas were studied. Likewise, the results corresponding to an intervention program carried out in the authors' hospital are presented. RESULTS: The global prevalence of urinary catheterization ranges from 13.1% to 14.6%. The proportion of closed systems did not surpass 56.4% of the total with this system being completely implemented only in one fourth of the hospitals studied. A significant variation was not observed in this phenomenon during the study period. In the authors' hospital, the increase observed in the prevalence of closed urinary catheterization was associated to a marked decrease in the prevalence of urinary infection with values ranging from 4.3% to 0.8%. CONCLUSIONS: The prevalence of the use of open type urinary catheterization in Spanish hospitals remains high. The efficacy of the implementation of control measures of the urinary drainage systems is clearly proved.

Cytologic diagnosis of extrapulmonary Pneumocystis carinii infection in pleural and ascitic fluid. Report of a case in a patient with the acquired immunodeficiency syndrome.

We present a case of an extrapulmonary Pneumocystis carinii infection in a human immunodeficiency virus-positive patient undergoing prophylactic treatment with pentamidine. The diagnosis was established in pleural and ascitic fluid, and the patient died before starting specific systemic treatment. We discuss the cytologic differences between pulmonary and extrapulmonary infections and the importance of careful screening for this pathogen in immunosuppressed patients.