Overall symptom severity as a patient-reported outcome measure for chronic rhinosinusitis: what it reflects and how to measure it.

BACKGROUND: The objective of this study was to identify how - and to what extent - overall symptom severity (OSS) score reflects individual chronic rhinosinusitis (CRS) symptoms and whether it can be measured using alternatives to the standard visual analog scale (VAS). METHODS: CRS patients from four sites across three continents rated their OSS scores, severities of nasal obstruction, nasal drainage, decreased sense of smell, facial pain/pressure and sleep disturbance using a standard VAS, VAS with labeled tick marks at every 1 centimeter, and by writing down their OSS on a scale of 0 - 100 (which was divided by 10), all of which lead to severity scores ranging from 0 - 10 in 0.1 intervals. Quality of life was measured using the SNOT-22 and EQ-5D VAS. RESULTS: In 311 CRS patients, OSS score was significantly correlated with SNOT-22 and EQ-5D VAS. OSS score was most greatly associated with the mean of all individual symptom severity scores. From individual CRS symptoms, OSS was most greatly associated with nasal obstruction followed by nasal drainage and facial pain/pressure severities. These results held true for participants with and without nasal polyps. Measurement of OSS and individual symptom severity scores using a standard VAS, tick-marked VAS, and write-in option had near-perfect consistency. CONCLUSIONS: We demonstrate for the first time that OSS largely reflects the mean of individual CRS symptom severities, although OSS is=== most weighted by nasal obstruction severity. OSS and individual symptom severity scores can be measured using a standard VAS, tick-marked VAS or write-in prompt with near-perfect consistency.

Effect of dietary supplementation of two fiber sources differing on fermentability and hydration capacity on performance, nutrient digestibility and cecal fermentation in broilers from 1 to 42 d of age.

A total of 378 Cobb-500 male broilers were used to evaluate the effects of 2 fiber sources, differing in hydration capacity and fermentability, on gastrointestinal tract development, apparent ileal digestibility and performance from 1 to 42d of age. There were 9 replicates per each of the 3 dietary treatments, all in mash form: a wheat-soybean control (CON) diet, CON diet diluted with 1.5% of wood lignocellulose (LC diet) as a non-fermentable insoluble fiber with high hydration capacity; and CON diluted with 1.5% of a mixture of fibers (ISFC diet) containing both lignified insoluble fiber and a prebiotic soluble fiber fraction from fructooligosaccharides. Additionally, the fermentability of both fiber sources (LC and ISFC) was determined by in vitro using cecal inoculum from broilers fed the experimental diets. Both LC and ISFC treatments impaired by 4% feed conversion ratio only during the first 7d (P = 0.003) compared with CON group. In the grower period (21-42d), the ISFC group showed the best growth (P = 0.039), and at 42d tended to show the highest body weight (P = 0.095). This agrees well with the highest ileal dry matter (P = 0.033) and organic matter (P = 0.043) digestibility observed in ISFC group and the similar trend observed for ileal protein digestibility (P = 0.099) at 42d. Also, at 42 d, absolute and relative (% body weight) digestive tract weights (P ≤ 0.041) and empty gizzard weights (P ≤ 0.034) were greater for LC and ISFC groups compared to CON. The cecal molar proportion of valeratewas greatest in ISFC group (P = 0.039). In vitro gas production was higher for ISFC than for LC substrate when using either a diet-adapted or non-adapted cecal inoculum (P < 0.05). These results show the interest in combining IF with prebiotic highly fermentable fiber, such as fructooligosaccharides, in broilers to improve nutrient digestibility and finishing performance.

Energy-Efficient Edge and Cloud Image Classification with Multi-Reservoir Echo State Network and Data Processing Units.

In an era dominated by Internet of Things (IoT) devices, software-as-a-service (SaaS) platforms, and rapid advances in cloud and edge computing, the demand for efficient and lightweight models suitable for resource-constrained devices such as data processing units (DPUs) has surged. Traditional deep learning models, such as convolutional neural networks (CNNs), pose significant computational and memory challenges, limiting their use in resource-constrained environments. Echo State Networks (ESNs), based on reservoir computing principles, offer a promising alternative with reduced computational complexity and shorter training times. This study explores the applicability of ESN-based architectures in image classification and weather forecasting tasks, using benchmarks such as the MNIST, FashionMnist, and CloudCast datasets. Through comprehensive evaluations, the Multi-Reservoir ESN (MRESN) architecture emerges as a standout performer, demonstrating its potential for deployment on DPUs or home stations. In exploiting the dynamic adaptability of MRESN to changing input signals, such as weather forecasts, continuous on-device training becomes feasible, eliminating the need for static pre-trained models. Our results highlight the importance of lightweight models such as MRESN in cloud and edge computing applications where efficiency and sustainability are paramount. This study contributes to the advancement of efficient computing practices by providing novel insights into the performance and versatility of MRESN architectures. By facilitating the adoption of lightweight models in resource-constrained environments, our research provides a viable alternative for improved efficiency and scalability in modern computing paradigms.

In situ analysis of neuronal injury and neuroinflammation during HIV-1 infection.

BACKGROUND: Since the introduction of combination antiretroviral therapy (cART) the brain has become an important human immunodeficiency virus (HIV) reservoir due to the relatively low penetration of many drugs utilized in cART into the central nervous system (CNS). Given the inherent limitations of directly assessing acute HIV infection in the brains of people living with HIV (PLWH), animal models, such as humanized mouse models, offer the most effective means of studying the effects of different viral strains and their impact on HIV infection in the CNS. To evaluate CNS pathology during HIV-1 infection in the humanized bone marrow/liver/thymus (BLT) mouse model, a histological analysis was conducted on five CNS regions, including the frontal cortex, hippocampus, striatum, cerebellum, and spinal cord, to delineate the neuronal (MAP2ab, NeuN) and neuroinflammatory (GFAP, Iba-1) changes induced by two viral strains after 2 weeks and 8 weeks post-infection. RESULTS: Findings reveal HIV-infected human cells in the brain of HIV-infected BLT mice, demonstrating HIV neuroinvasion. Further, both viral strains, HIV-1JR-CSF and HIV-1CH040, induced neuronal injury and astrogliosis across all CNS regions following HIV infection at both time points, as demonstrated by decreases in MAP2ab and increases in GFAP fluorescence signal, respectively. Importantly, infection with HIV-1JR-CSF had more prominent effects on neuronal health in specific CNS regions compared to HIV-1CH040 infection, with decreasing number of NeuN+ neurons, specifically in the frontal cortex. On the other hand, infection with HIV-1CH040 demonstrated more prominent effects on neuroinflammation, assessed by an increase in GFAP signal and/or an increase in number of Iba-1+ microglia, across CNS regions. CONCLUSION: These findings demonstrate that CNS pathology is widespread during acute HIV infection. However, neuronal loss and the magnitude of neuroinflammation in the CNS is strain dependent indicating that strains of HIV cause differential CNS pathologies.

Dysfunction of proprioceptive sensory synapses is a pathogenic event and therapeutic target in mice and humans with spinal muscular atrophy.

Spinal muscular atrophy (SMA) is a neurodegenerative disease characterized by a varying degree of severity that correlates with the reduction of SMN protein levels. Motor neuron degeneration and skeletal muscle atrophy are hallmarks of SMA, but it is unknown whether other mechanisms contribute to the spectrum of clinical phenotypes. Here, through a combination of physiological and morphological studies in mouse models and SMA patients, we identify dysfunction and loss of proprioceptive sensory synapses as key signatures of SMA pathology. We demonstrate that SMA patients exhibit impaired proprioception, and their proprioceptive sensory synapses are dysfunctional as measured by the neurophysiological test of the Hoffmann reflex (H-reflex). We further show that loss of excitatory afferent synapses and altered potassium channel expression in SMA motor neurons are conserved pathogenic events found in both severely affected patients and mouse models. Lastly, we report that improved motor function and fatigability in ambulatory SMA patients and mouse models treated with SMN-inducing drugs correlate with increased function of sensory-motor circuits that can be accurately captured by the H-reflex assay. Thus, sensory synaptic dysfunction is a clinically relevant event in SMA, and the H-reflex is a suitable assay to monitor disease progression and treatment efficacy of motor circuit pathology.

Increased insulin-like growth factor 1 concentrations in a population of non-diabetic cats with overweight/obesity.

Feline hypersomatotropism (HST) is typically associated with diabetes mellitus (DM), whereas HST without concurrent DM has only been reported in a few cases. Weight gain may be observed in cats with HST. The aims of this study were to evaluate circulating insulin-like growth factor-1 (IGF-1) in non-diabetic cats with overweight/obesity, to screen this population for the presence of HST, and to assess whether there is a correlation between body weight/body condition score (BCS) and serum IGF-1 concentration in overweight/obese cats. In this prospective study, 80 overweight/obese cats from referral centers in Buenos Aires (Argentina) were evaluated. Serum IGF-1 was measured as part of the routine tests for overweight/obesity. Non-diabetic cats were included in the study if they had a BCS>6/9. Twenty-nine cats were classified as overweight (BCS 7/9), whereas 51 were classified as obese (BCS 8-9/9). Median serum IGF-1 concentrations of cats with BCS 7/9, 8/9, and 9/9 were 570 ng/ml (range 123-1456 ng/ml), 634 ng/ml (range 151-1500 ng/ml), and 598 ng/ml (range 284-2450 ng/ml), respectively. There was a positive linear correlation between serum IGF-1 concentrations and body weight (r= 0.24, 95% CI 0.01-0.44 P=0.03), and between IGF-1 and BCS (r= 0.27, 95% CI 0.08-0.44 P=0.004). In total, 8.75% (95% confidence interval 3.6-17.2%) of the cats with overweight/obesity had IGF-1 concentrations >1000 ng/ml. Pituitary enlargement was detected on computed tomography in 4/7 cases. These seven cats showed varying degrees of phenotypic changes consistent with acromegaly. A proportion of 8.75 % of overweight/obese non-diabetic cats from referral centers in Buenos Aires had serum IGF-1 concentration in a range consistent with HST in diabetic cats. Likewise, 5% of overweight/obese cats were likely to be diagnosed with HST, supported by evidence of pituitary enlargement. Serum IGF-1 concentrations were positively correlated with body weight and BCS in this population of cats. This study highlights the relevance of screening different populations of non-diabetic cats to increase the detection of HST/acromegaly.

Clinical and genetic factors involved in Porto-sinusoidal vascular disorder after oxaliplatin exposure.

BACKGROUND AND AIMS: Oxaliplatin (OX) has been described as a potential etiologic agent for porto-sinusoidal vascular disorder (PSVD). Our aim was to describe the natural history of PSVD due to OX in colon cancer (CRC) and identify risk factors for its development. METHODS: We made a multicenter retrospective case-control (ratio 1:3) study with patients diagnosed of PSVD-OX. Baseline data, end of treatment, years of follow-up and diagnosis of PSVD were collected and compared to controls (without PSVD). Besides, 16 different SNPs were selected from bibliography and analyzed by genotyping in the case group to identify potential genetic risk factors. RESULTS: 41 cases were identified, with a median time to PSVD diagnosis after the end of OX of 34 months. Spleen diameter was the strongest predictor of PSVD during treatment (OR 43.94 (14.48-133.336); p < 0.0001). Additionally, thrombocytopenia (<150 × 10^9) at one year was a significant disease risk marker (OR 9.35; 95% CI: 3.71-23.58; p = 0.001). We could not establish any significant association between the selected SNPs and PSVD diagnosis. CONCLUSION: The increase of spleen diameter is the strongest predictor of PSVD in patients treated with OX for CRC. These patients could be candidates for a specific follow-up of portal hypertension-related complications.

Variaciones de las células de cuadrícula y de posicionamiento de la corteza entorrinal y del giro dentado de 6 humanos de 56 a 87 años / Variations of the grid and place cells in the entorhinal cortex and dentate gyrus of 6 individuals aged 56 to 87 years

Introducción: La relación entre la corteza entorrinal y el hipocampo ha sido estudiada por diferentes autores, que han destacado la importancia de las células de cuadrícula, las células de posicionamiento y la conexión trisináptica en los procesos que regulan: la persistencia de la memoria espacial, explícita y reciente, y su posible afección con el envejecimiento. Objetivo: Observar si existen diferencias en el tamaño y número de células de cuadrícula contenidas en la lámina iii de la corteza entorrinal y en la capa granular del giro dentado del hipocampo de pacientes mayores. Métodos: Realizamos estudios posmortem del cerebro de 6 sujetos de edades comprendidas entre los 56 y 87 años. Los cortes de cerebros que contenían el giro dentado del hipocampo y la corteza entorrinal adyacente se tiñeron con el método de Klüver-Barrera, después se midió, mediante el programa Image J, el área neuronal individual, el área neuronal total, así como el número de neuronas, contenidas en cuadrículas rectangulares a nivel de la lámina iii de la corteza entorrinal y la lámina ii del giro dentado y se llevó a cabo un análisis estadístico. Resultados: Se ha observado una reducción de la población celular de la capa piramidal externa de la corteza entorrinal, así como de las neuronas de la capa granular del giro dentado relacionada con el envejecimiento. Conclusión: Nuestros resultados indican que el envejecimiento produce una disminución en el tamaño y la densidad neuronal en las células de cuadrícula de la corteza entorrinal y de posicionamiento del giro dentado.(AU)

Introduction: The relationship between the entorhinal cortex and the hippocampus has been studied by different authors, who have highlighted the importance of grid cells, place cells, and the trisynaptic circuit in the processes that they regulate: the persistence of spatial, explicit, and recent memory and their possible impairment with ageing. Objective: We aimed to determine whether older age causes changes in the size and number of grid cells contained in layer III of the entorhinal cortex and in the granular layer of the dentate gyrus of the hippocampus. Methods: We conducted post-mortem studies of the brains of 6 individuals aged 56-87 years. The brain sections containing the dentate gyrus and the adjacent entorhinal cortex were stained according to the Klüver-Barrera method, then the Image J software was used to measure the individual neuronal area, the total neuronal area, and the number of neurons contained in rectangular areas in layer III of the entorhinal cortex and layer II of the dentate gyrus. Statistical analysis was subsequently performed. Results: We observed an age-related reduction in the cell population of the external pyramidal layer of the entorhinal cortex, and in the number of neurons in the granular layer of the dentate gyrus. Conclusion: Our results indicate that ageing causes a decrease in the size and density of grid cells of the entorhinal cortex and place cells of the dentate gyrus.(AU)

Detección de la infiltración de la cadena mamaria interna en pacientes con cáncer de mama mediante PET/RM con 18F-FDG y sus implicaciones terapéuticas / Detection of internal mammary chain infiltration in breast cancer patients by [18F]FDG PET/MRI: Therapy implications

Objetivo: Evaluar la tasa de detección y la implicación terapéutica de la infiltración de la cadena mamaria interna (ICMI) mediante tomografía por emisión de positrones (PET) y resonancia magnética (RM) con 18F-fluorodesoxiglucosa (18F-PET/RM) en la estadificación de pacientes con cáncer de mama. Método: Estudio prospectivo, 41 mujeres con cáncer de mama (estadio ≥ IIB) estadificadas mediante 18F-FDG-PET/RM. Estudio en dos fases: imágenes mamarias (decúbito prono), cuerpo completo (supino). Estadificación TNM por consenso entre especialista en Medicina Nuclear y Radiología. Estudio vaso aferente (VA) a cadena mamaria interna (CMI) por RM mamaria. Correlación ICMI con edad, VA-CMI, estadificación T, cuadrante, infiltración axilar y a distancia. Revaloración terapéutica en comité multidisciplinar. Resultados: Tasa de detección de ICMN de 34% (14/41), siendo 8/14 < 55 años. Todas las 14 pacientes con ICMI muestran VA-CMI, en seis de ellas (43,9%) sin VA-axilar. De 27/41 sin ICMI, en 13 (48,1%) solo VA-axilar, en los 14 restantes (51,9%) VA-axilar y VA-CMI. Un total de 57% (8/14) son multicéntricos y 42% (6/14) focales, en cuadrantes internos en 4/6 (66,7%). En 1/14 (7,1%) solo ICMI, en 9/14 (64,3%) axilar y CMI y en 4/14 (28,6%) lesiones a distancia. Decisión del comité: sin tratamiento adicional en 27/41 (65,8%), radioterapia torácica en 10/41 (24,4%) y terapia sistémica en 4/41 (9,7%). Conclusión: La tasa de detección de la ICMI en la estadificación del cáncer de mama mediante 18F-FDG PET/RM es de 34%. Son factores asociados la edad, los tumores multicéntricos, los de cuadrantes internos, la existencia de VA-CMI, la estadificación NM. La evidencia de ICMI permite la individualización de la terapia, indicando la radioterapia torácica en 24,4%.(AU)

Objective: To evaluate the detection rate and therapeutic implication of the infiltration of the internal mammary chain (IMCI) by [18F]FDG PET/MRI for staging of patients with breast cancer. Methods: Prospective study including 41 women with breast cancer (stage ≥IIB) staged by [18F]FDG PET/MR. Two-phase exam: breast imaging (prone), whole-body (supine). TNM stage assessed by peer consensus with Nuclear Medicine and Radiology specialists. Study of the afferent vessel (AV) to IMC by breast MRI. IMCI was correlated with age, AV-IMC, T stage, breast quadrants, axillary and distant infiltration. Therapeutic re-evaluation by a multidisciplinary committee. Results: IMCI detection rate of 34% (14/41), with 8/14 patients under 55 years of age. All 14 patients with IMCI showed AV-IMC, 6 of them (43.9%) without VA-axillary. Of 27/41 patients without IMCI, in 13 (48.1%) only AV-axillary was found, in the remaining 14 (51.9%), AV-axillary and AV-IMC was found. In 57% (8/14) tumours were multicentric and 42% (6/14) focal, in inner quadrants in 4/6 (66.7%). In 1/14 patient (7.1%) only IMCI was found, in 9/14 (64.3%) axillary and IMC, in 4/14 patients (28.6%) distant lesions were detected. Committee re-evaluation: no further treatment in 27/41 patients (65.8%), thoracic radiotherapy in 10/41 patients (24.4%), systemic therapy in 4/41 patients (9.7%). Conclusion: Our detection rate of IMCI in breast cancer staging by [18F]FDG PET/MR was 34%. Related factors were age, multicentric tumours, inner quadrants, detection of AV-IMC, NM staging.The evidence of IMCI allowed tailored therapy, with thoracic radiotherapy implementation in 24.4% of patients.(AU)

Situación actual de los anticoagulantes orales de acción directa en atención primaria de España. Posicionamiento de SEMERGEN en 2023 / Current situation of direct oral anticoagulants in primary care in Spain: Positioning of SEMERGEN in 2023

La anticoagulación oral es clave para disminuir el riesgo de ictus en la fibrilación auricular. Aunque clásicamente los antagonistas de la vitaminaK (AVK) se han empleado para este fin, han sido ampliamente superados por los anticoagulantes orales de acción directa (ACOD), como lo demuestran las evidencias provenientes de los ensayos clínicos, estudios de vida real y poblacionales. De hecho, todas las guías de práctica clínica recomiendan su uso de manera preferencial sobre los AVK. Sin embargo, en España la prescripción de los ACOD está subordinada a un visado de inspección que recoge las condiciones clínicas definidas en el Informe de Posicionamiento Terapéutico de la Agencia Española del Medicamento, y que todavía impone importantes restricciones a su uso, limitando los beneficios del empleo de los ACOD en los pacientes con fibrilación auricular (FA), y generando además inequidades entre las diferentes comunidades autónomas. De hecho, el empleo de los ACOD en España es muy inferior a los países de nuestro entorno. Esto ha provocado que en otros países ha disminuido la incidencia de ictus isquémico a nivel poblacional, junto con una reducción del coste por paciente con FA, pero en España este descenso ha sido discreto. Por todo ello, y en aras de la sostenibilidad del sistema sanitario, pedimos la eliminación del visado para que los ACOD se puedan prescribir de acuerdo a las recomendaciones realizadas por las guías. Además, también apostamos por el refuerzo de la formación y de las decisiones consensuadas con el paciente, siendo el médico de familia un actor clave en la protección del paciente con FA.(AU)

Oral anticoagulation is the key to reduce the risk of stroke in atrial fibrillation. Although vitaminK antagonists (VKA) have classically been used for this purpose, they have been largely overcome by direct oral anticoagulants (DOAC), as demonstrated by evidence from clinical trials, real-life and population studies. In fact, all clinical practice guidelines recommend their use preferentially over VKA. However, in Spain the prescription of DOAC is subordinated to an inspection visa that includes the clinical conditions defined in the Therapeutic Positioning Report of the Spanish Medicines Agency, and that still imposes important restrictions on their use, limiting the benefits of using DOACs in patients with atrial fibrillation (AF), and also generating inequalities between the different autonomous communities. In fact, the use of DOAC in Spain is much lower than that observed in neighboring countries. This has made that while in other countries the incidence of ischemic stroke has decreased at the population level, along with a reduction in the cost per patient with AF, in Spain this decrease has been modest. For all these reasons, and for assuring the sustainability of the health care system, we ask for the elimination of the visa so that DOAC can be prescribed according to the recommendations made by the guidelines. In addition, we are also committed to reinforce medical education and decisions made by consensus with the patient, with the primary care physician acquiring a key role in the protection of the patient with AF.(AU)

Prevalencia de anticuerpos neutralizantes frente al SARS-CoV-2 inducidos tras 2 dosis de vacuna BNT162b2 (Pfizer–BioNTech) en trabajadores sanitarios / Prevalence of neutralizing antibodies against SARS-CoV-2 using a rapid serological test in health workers of a Spanish Department of Health in Alicante (Spain) before the booster dose of the vaccine

Fundamento: Estudiar la prevalencia de anticuerpos neutralizantes en el personal sanitario y de apoyo tras la administración de la segunda dosis de vacuna BNT162b2 (Pfizer–BioNTech). Material y métodos: En diciembre 2021 llevamos a cabo un estudio en el Departamento de Salud de Orihuela, Alicante (España), formado por 1.500 trabajadores. En los participantes del estudio, recogimos variables demográficas y realizamos un test «point-of-care» (POC) de inmunocromatografía para medir la presencia de anticuerpos neutralizantes (OJABIO® SARS-CoV-2 Neutralizing Antibody Detection Kit, fabricado por Wenzhou OJA Biotechnology Co., Ltd.- Wenzhou, Zhejiang, China) antes de la administración de la tercera dosis de vacuna. Resultados: Obtuvimos información completa de 964 (64%) trabajadores, siendo 290 varones y 674 mujeres. La edad media fue de 45,8 años (mín: 18, máx: 68) y el tiempo desde la última dosis (TUD) de vacuna fue 40,5 semanas (mín: 1,71; máx: 47,71). Un total de 131 (13,5%) habían padecido infección por SARS-CoV-2 confirmada mediante RT-PCR. La proporción de sujetos con presencia de anticuerpos neutralizantes fue de 38,5%. En el análisis multivariable el TUD de vacuna (razón de probabilidades ajustada [ORa] semana: 1,07; IC 95%: 1,04; 1,09) y la infección previa por SARS-CoV-2 (ORa: 3,7; IC 95%: 2,39; 5,63) mostraron asociación estadísticamente significativa con la presencia de anticuerpos neutralizantes. Conclusiones: El TUD de vacuna y la infección previa por SARS-CoV-2 determinaron la presencia de anticuerpos neutralizantes en 38,5% del personal sanitario y personal de apoyo.(AU)

Aim: To study the prevalence of neutralizing antibodies in healthcare workers and healthcare support personnel after the administration of the second dose of the BNT162b2 vaccine (Pfizer-BioNTech). Materials and methods: In December 2021, we undertook a study in the Health Department in Orihuela, Alicante (Spain), which consists of 1500 workers. We collected demographic variables about the study participants, and we performed a «point-of-care» immunochromatography test to measure the presence of neutralizing antibodies (OJABIO® SARS-CoV-2 Neutralizing Antibody Detection Kit, manufactured by Wenzhou OJA Biotechnology Co., Ltd. Wenzhou, Zhejiang, China) before the administration of the third dose of the vaccine. Results: We obtained complete information about 964 (64%) workers, which consisted of 290 men and 674 women. The average age was 45,8 years (min. 18, max. 68) and the average time since the last dose of the vaccine was 40,5 weeks (min. 1,71, max. 47,71). A total of 131 participants (13,5%) had suffered infection by SARS-CoV-2 confirmed using RT-PCR. The proportion of participants who showed presence of neutralizing antibodies was 38,5%. In the multivariable analysis, the time since the last dose of the vaccine (aOR week: 1,07; 95%CI: 1,04; 1,09) and previous infection by SARS-CoV-2 (aOR: 3,7; 95CI: 2,39; 5,63) showed a statistically significant association with the presence of neutralizing antibodies. Conclusions: The time since the administration of the last dose of the vaccine and the previous infection by SARS-CoV-2 determined the presence of neutralizing antibodies in 38,5% of the healthcare workers and support workers.(AU)

Photocatalytic activity enhancement of two-step and one-pot synthesis of Pd/ZnO nanocomposites: an experimental and DFT study.

Pd/ZnO nanocomposites were successfully synthesized by means of one and two pot synthesis and applied in the photodegradation of Rh6G. The nanocomposites were characterized by XRD, SEM, TEM, FTIR and micro-Raman spectroscopies. It was found the presence of PdZn2, PdO and agglomerated particles in the support surface for the Palladium-based nanocomposites fabricated by one-pot route; the two-step method allowed the formation of spherical Pd nanoparticles, with homogeneous distribution in the nanocomposite matrix, with an average size of 2.16 nm. The results show higher photocatalytic efficiency for the samples fabricated under the two-step approach compared to the one-pot synthesis. Based on experimental results, density functional theory (DFT) calculations were carried out to understand the enhancement photocatalytic of Pd/ZnO nanocomposites. To achieve it, the ZnO (001) and (101) surfaces were built and decorated by different Pd coverages. The theoretical results indicated two different photocatalytic mechanisms. In ZnO (001) case, the electrons flowed from surface to Pd, generating the superoxide radical anion (⋅O2-). Furthermore, the density of states of the ZnO (001) surface was modified by impurity Pd-d states at proximity to the conduction states, which may work as electron acceptors states. On the other hand, we found that the electrons flow from Pd to ZnO (101) surface, inducing the formation of ⋅OH and ⋅O2- for the degradation of Rh6G. The density of states of the ZnO (101) revealed a reduction in its bandgap, due to Pd-d states localized above valence states. Hence, our theoretical results suggest that the Pd-d states may facilitate the mobility of electrons and holes in (001) and (101) surfaces, respectively, reducing the rate of charge recombination.