ABSTRACT
In this paper, the authors describe the fabrication of nanocomposite chitosan-based systems of zinc oxide (ZnO), silver (Ag) and Ag-ZnO. Recently, the development of coated screen-printed electrodes using metal and metal oxide nanoparticles (NPs) for the specific detection and monitoring of different cancer tumors has been obtaining important results. Ag, ZnO NPs and Ag-ZnO prepared by the hydrolysis of zinc acetate blended with a chitosan (CS) matrix were used for the surface modification of screen-printed carbon electrodes (SPCEs) in order to analyze the electrochemical behavior of the typical redox system of a 10 mM potassium ferrocyanide-0.1 M buffer solution (BS). The solutions of CS, ZnO/CS, Ag/CS and Ag-ZnO/CS were prepared in order to modify the carbon electrode surface, and were measured at different scan rates from 0.02 V/s to 0.7 V/s by cyclic voltammetry. The cyclic voltammetry (CV) was performed on a house-built potentiostat (HBP). The cyclic voltammetry of the measured electrodes showed the influence of varying the scan rate. The variation of the scan rate has an influence on the intensity of the anodic and cathodic peak. Both values of currents (anodic and cathodic currents) have higher values for 0.1 V/s (Ia = 22 µA and Ic = -25 µA) compared to the values for 0.06 V/s (Ia = 10 µA and Ic = -14 µA). The CS, ZnO/CS, Ag/CS and Ag-ZnO/CS solutions were characterized using a field emission scanning electron microscopy (FE-SEM) with EDX elemental analysis. The modified coated surfaces of screen-printed electrodes were analyzed using optical microscopy (OM). The present coated carbon electrodes showed a different waveform compared to the voltage applied to the working electrode, depending on the scan rate and chemical composition of the modified electrodes.
ABSTRACT
Corona virus (COVID-19) is an epidemy of respiratory disease caused by a novel corona virus and it was declared by the World Health Organization (WHO) to be a global health pandemic emergency. Due to the neuropsychiatric manifestation of Covid-19 that have been associated with psychotic disorders, in this paper we choose to present a case from "Elena Doamna" Psychiatric Hospital from Galati, Romania and to correlate it with other cases from literature in a mini review presentation. In our paper, we present the case of a patient of 44-year-old men, with no past psychiatric history whose behavior included psycho-motor agitation, perception and thinking disorders, disorganized behaviour, attempted suicide by stabbing. The last perspectives from the two years of pandemic together with psychiatric disease linked the virus infections with psychosis to the main concern that Covid-19 could determine psychiatric disorders. There were also presented same literature studies of patients with no personal pathological history in the psychiatric field which developed psychiatric disorders after COVID-19 infection. SARS-CoV-2 has a psychological impact on the mental health status of the worldwide and, especially when it is associated with psychotic symptoms and can affect the quality-of-life. In some cases, the virus affected the brain and as a result, the psychosis symptoms could be an emerging phenomenon associated with the corona virus. Based on the DSM V and ICD-10 criteria, the diagnosis was of acute psychiatric disorders with symptoms of schizophrenia (F23.1). The case report and review reliefs that there is a causal link between the SARS CoV-2 infection and mental disorders, which is currently being investigated.
ABSTRACT
Bottom-up approaches in solutions enable the low-temperature preparation of hybrid thin films suitable for printable transparent and flexible electronic devices. We report the obtainment of new transparent PMMA/ZrO2 nanostructured -building blocks (nBBs) hybrid thin films (61-75 nm) by a modified sol-gel method using zirconium ethoxide, Zr(OEt)4, and 3-methacryloxypropyl trimethoxysilane (MPS) as a coupling agent and methylmethacrylate monomer (MMA). The effect of low-temperature and UV irradiation on the nBBs gel films is discussed. The thermal behaviors of the hybrid sols and as-deposed gel films were investigated by modulated thermogravimetric (mTG) and differential scanning calorimetry (DSC) analysis. The chemical structure of the resulted films was elucidated by X-ray photoelectron (XPS), infrared (IR) and Raman spectroscopies. Their morphology and crystalline structure were observed by scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HR-TEM), and grazing incidence X-ray diffraction. The cured films show zirconia nanocrystallites of 2-4 nm in the hybrid matrix and different self-assembled structures for 160 °C or UV treatment; excellent dielectric behavior, with dielectric constant values within 6.7-17.9, depending on the Zr(OEt)4:MMA molar ratio, were obtained.
