Lead molybdate : a promising material for optoelectronics and photocatalysis

The growing interest in the use of light as an information and energy carrier has led to an increasing demand for new materials, characterised by particular photoelectrochemical properties. The aim of this work is to introduce a wide band gap semiconductor – PbMoO4 with a detailed description of its synthesis procedure and product characterisation. The emphasis was put on its electronic structure and photoelectrochemical properties in order to evaluate the mechanism of the photoelectrochemical photocurrent switching effect (the PEPS effect). This phenomenon may be utilized in the construction of simple logic devices (e.g. logic gates or switches) or more complex optoelectronic circuits. Lead molybdate in the form of fine powder was obtained via a microwave assisted hydrothermal route. It was found that the composition of the reaction mixture (i.e. the ratio between lead and molybdate ions) influences the morphology and the electronic structure of the semiconductor. The photoelectrochemical characterization revealed that PbMoO4 in the presence of the Ce4+/Ce3+ redox couple exhibits the PEPS effect regardless of the presence of oxygen in the electrolyte. This may be explained in terms of oxidation/reduction processes of cerium(III)/cerium(IV) species. An attempt to modify the surface via the adsorption of alizarin onto PbMoO4 was also made. The spectroscopic characterization and DFT calculations performed for such an organic–inorganic hybrid material revealed that the dye binds to MoVI centres which are exposed on the surface. Alizarin adsorbed onto PbMoO4 strongly enhances the cathodic photocurrent generation. At the same time, however, the anodic photocurrent diminishes. Therefore, literally no switching effect occurs for such a system. Nonetheless, the generation of intense cathodic photocurrent may be utilized in photocatalysis, e.g. during the photoreduction of metal ions or the generation of reactive oxygen species and/or solar fuels

Photoelectrochemistry of n-type antimony sulfoiodide nanowires

In the presented work the photoelectrochemical properties of SbSI along with the electronic structure (i.e. conduction and valence band edge potentials as well as conductivity type) of sonochemically obtained nanowires are discussed for the fi rst time. The spectroscopic investigations indicate interesting optical properties, including surface isotope effect and excitonic emission. The photoelectrochemical investigation of SbSI revealed the occurrence of the photoelectrochemical photocurrent switching effect. It may be de fi ned as a change in photocurrent direction (generated at the illuminated semiconducting electrode immersed in electrolyte) due to an appropriate polarization of the electrode versus the reference electrode. It is often observed for semiconductors as a result of the reduction of molecular oxygen dissolved in the electrolyte. However, in the case of SbSI, the photocurrent switching was recorded regardless of the presence of molecular oxygen in the electrolyte, probably due to the reduction of triiodide species formed at anodic polarization of the SbSI electrode, in an iodide-containing electrolyte. The switching potential (i.e. the potential where anodic-to-cathodic photocurrent transition occurs) equals to ca. 0.4 V versus standard hydrogen electrode, which is close to the formal potential of the I − /I 3 − redox couple. Therefore, this semiconducting material is of potential interest for the construction of new photovoltaic systems, novel optoelectronic switches and logic devices

Molecules, semiconductors, light and information: Towards future sensing and computing paradigms

Over the last few years we have witnessed a great progress in the research devoted to unconventional computing - an unorthodox approach to information handling. It includes both novel algorithms and computing paradigms as well as completely new elements of circuitry: whole organisms (e.g., Physarum species), DNA, enzymes, various biomolecules, molecular and nanoparticulate materials. One of the biggest challenges in this field is the realisation of in-materio computing - i.e., the utilisation of properties of pristine materials, instead of high-tech structures - for advanced information processing. In this review we present recent achievements in the design of logic devices (binary, ternary and fuzzy) implemented in molecular and nanoscale components, photoelectrochemical chemosensing, photoactive memristive devices and reservoir computing systems. A common denominator for all these devices is the involvement of molecular species, semiconducting nanoparticles and light in information processing. (C) 2018 Elsevier B.V. All rights reserved

Clinical and Epidemiological Characteristics of 1283 Pediatric Patients with Coronavirus Disease 2019 during the First and Second Waves of the Pandemic—Results of the Pediatric Part of a Multicenter Polish Register SARSTer

This prospective multicenter cohort study aimed to analyze the epidemiological and clinical characteristics of coronavirus disease 2019 (COVID-19) in children. The study, based on the pediatric part of the Polish SARSTer register, included 1283 children (0 to 18 years) who were diagnosed with COVID-19 between 1 March 2020 and 31 December 2020. Household contact was reported in 56% of cases, more frequently in younger children. Fever was the most common symptom (46%). The youngest children (0–5 years) more frequently presented with fever, rhinitis and diarrhea. Teenagers more often complained of headache, sore throat, anosmia/ageusia and weakness. One fifth of patients were reported to be asymptomatic. Pneumonia was diagnosed in 12% of patients, more frequently in younger children. During the second wave patients were younger than during the first wave (median age 53 vs. 102 months, p < 0.0001) and required longer hospitalization (p < 0.0001). Significantly fewer asymptomatic patients were noted and pneumonia as well as gastrointestinal symptoms were more common. The epidemiological characteristics of pediatric patients and the clinical presentation of COVID-19 are age-related. Younger children were more frequently infected by close relatives, more often suffered from pneumonia and gastrointestinal symptoms and required hospitalization. Clinical courses differed significantly during the first two waves of the pandemic

Clinical Course and Severity of COVID-19 in 940 Infants with and without Comorbidities Hospitalized in 2020 and 2021: The Results of the National Multicenter Database SARSTer-PED

This study aimed to analyze the differences in severity and clinical characteristics of COVID-19 in infants hospitalized in Poland in 2021, when the dominance of variants of concern (VOCs) alpha and delta was reported, compared to 2020, when original (wild) SARS-CoV-2 was dominant (III–IV vs. I–II waves of the pandemic, respectively). In addition, the influence of the presence of comorbidities on the clinical course of COVID-19 in infants was studied. This multicenter study, based on the pediatric part of the national SARSTer database (SARSTer-PED), included 940 infants with COVID-19 diagnosed between March 1, 2020, and December 31, 2021, from 13 Polish inpatient centers. An electronic questionnaire, which addressed epidemiological and clinical data, was used. The number of hospitalized infants was significantly higher in 2021 than in 2020 (651 vs. 289, respectively). The analysis showed similar lengths of infant hospitalization in 2020 and 2021, but significantly more children were hospitalized for more than 7 days in 2020 (p p < 0.0001). Severe and critical conditions were significantly more common among children with comorbidities. More infants were hospitalized during the period of VOCs dominance, especially the delta variant, compared to the period of wild strain dominance, even though indications for hospitalization did not include asymptomatic patients during that period. The course of COVID-19 was mostly mild, characterized mainly by fever and respiratory symptoms. Comorbidities, particularly from the cardiovascular system and prematurity, were associated with a more severe course of the disease in infants