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In this study, a novel perovskite solar cell (PSC) architecture is presented that utilizes an HTL-free configuration with formamide tin iodide (FASnI3) as the active layer and fullerene (C60) as the electron transport layer (ETL), which represents a pioneering approach within the field. The elimination of hole transport layers (HTLs) reduces complexity and cost in PSC heterojunction structures, resulting in a simplified and more cost-effective PSC structure. In this context, an HTL-free tin HC(NH2)2SnI3-based PSC was simulated using the solar cell capacitance simulator (SCAPS) within a one-dimensional framework. Through this approach, the device performance of this novel HTL-free FASnI3-based PSC structure was engineered and evaluated. Key performance parameters, including the open-circuit voltage (Voc), short-circuit current density (Jsc), fill factor (FF), power conversion efficiency (PCE), I-V characteristics, and quantum efficiency (QE), were systematically assessed through the modulation of physical parameters across various layers of the device. A preliminary analysis indicated that the HTL-free configuration exhibited improved I-V characteristics, with a PCE increase of 1.93% over the HTL configuration due to improved electron and hole extraction characteristics, reduced current leakage at the back contact, and reduced trap-induced interfacial recombination. An additional boost to the device's key performance parameters has been achieved through the further optimization of several physical parameters, such as active layer thickness, bulk and interface defects, ETL thickness, carrier concentration, and back-contact materials. For instance, increasing the thickness of the active layer PSC up to 1500 nm revealed enhanced PV performance parameters; however, further increases in thickness have resulted in performance saturation due to an increased rate of hole–electron recombination. Moreover, a comprehensive correlation study has been conducted to determine the optimum thickness and donor doping level for the C60-ETL layer in the range of 10–200 nm and 1012–1019 cm−3, respectively. Optimum device performance was observed at an ETL-C60 ultra-thin thickness of 10 nm and a carrier concentration of 1019 cm−3. To maintain improved PCEs, bulk and interface defects must be less than 1016 cm−3 and 1015 cm−3, respectively. Additional device performance improvement was achieved with a back-contact work function of 5 eV. The optimized HTL-free FASnI3 structure demonstrated exceptional photovoltaic performance with a PCE of 19.63%, Voc of 0.87 V, Jsc of 27.86 mA/cm2, and FF of 81%. These findings highlight the potential for highly efficient photovoltaic (PV) technology solutions based on lead-free perovskite solar cell (PSC) structures that contribute to environmental remediation and cost-effectiveness. [ABSTRACT FROM AUTHOR]

Epilepsy is a chronic brain disorder that is characterized by repetitive un-triggered seizures that occur severally within 24 h or more. Non-pharmacological methods for the management of epilepsy were discussed. The non-pharmacological methods include the vagus nerve stimulation (VNS) which is subdivided into invasive and non-invasive techniques. For the non-invasive techniques, the auricular VNS, stimulation of the cervical branch of vagus nerve in the neck, manual massage of the neck, and respiratory vagal nerve stimulation were discussed. Similarly, the stimulation parameters used and the mechanisms of actions through which VNS improves seizures were also discussed. Use of VNS to reduce seizure frequency has come a long way. However, considering the cost and side effects of the invasive method, non-invasive techniques should be given a renewed attention. In particular, respiratory vagal nerve stimulation should be considered. In doing this, the patients should for instance carry out slow-deep breathing exercise 6 to 8 times every 3 h during the waking hours. Slow-deep breathing can be carried out by the patients on their own; therefore this can serve as a form of self-management. Epilepsy can interfere with the patients' ability to carry out their daily activities and ultimately affect their quality of life. Medications are used to manage epilepsy; but they often have their serious side effects. Vagus nerve stimulation (VNS) is gaining ground especially in the management of refractory epilepsy. The VNS is administered through either the invasive or the non-invasive methods The invasive method of VNS like the medication has potential side effects, and can be costly. The non-invasive method includes auricular VNS, stimulation of the neck muscles and skin and respiratory vagal nerve stimulation via slow-deep breathing exercises. The respiratory vagal nerve stimulation via slow-deep breathing exercises seems easy to administer even by the patients themselves. Consequently, it is our opinion that patients with epilepsy be made to carry out slow-deep breathing exercise 6–8 times every 3 h during the waking hours. [ABSTRACT FROM AUTHOR]

A contrast agent with specific characteristics is essential for high-quality magnetic resonance imaging (MRI). It plays a crucial role in enhancing the visibility of certain tissues and structures, making it imperative for diagnostic procedures. Superparamagnetic iron oxide nanoparticles (SPIONs) have emerged as a promising alternative to traditional contrast agents for MRI due to their nontoxicity and superior magnetic properties. However, a suitable surface coating strategy is needed to produce polymer-coated SPIONs with controllable sizes in order to enhance their stability and biocompatibility. This study presents a novel one-pot synthesis method for the production of highly stable polyvinylpyrrolidone (PVP)-coated SPIONs. By systematically manipulating the physicochemical properties of SPIONs, the effect of different molecular weights of PVP was studied. The results showed that SPIONs coated with PVP with molecular wight 40,000 g/mol (40 K) exhibited a high magnetization (Ms = 48.4 emu/g), an average size distribution (11.61 nm), and excellent stability. The relaxivity of coated and uncoated SPIONs was investigated using MRI images. The results revealed that the (r2/r1) ratio of PVP40K-SPIONs was 72.55, compared to 55.72 for the bare SPIONs, making them a highly promising T2-contrast agent for future development of MRI applications. This study opens new avenues for the development of biocompatible and stable SPIONs for improved medical diagnostic and imaging. [ABSTRACT FROM AUTHOR]

This study aims to evaluate the average density, mechanical stability, and the suitability of Rhizophora spp. particleboard bonded with epoxy resin as tissue-equivalent phantom materials. The particleboards were fabricated with added epoxy at levels of 0%, 5%, 10%, and 15%. CT scan was used to evaluate the epoxy distribution. The sample with 15% epoxy level complied with the Japanese Industrial Standards. Moreover, the crystallinity was measured by microscopic analysis and X-ray diffraction (XRD). The results showed that the values of mass density and effective atomic number of the studied samples were well agreed and close to the value of water. Both microscopic analysis and XRD results showed the utility of epoxy in filling up the gaps and increasing the crystallinity. In addition, the standard deviation (SD) value of fabricated particleboard bonded with 15% epoxy resin provided a good matching with the SD value of Catphan 600 phantom. Furthermore, 15% of epoxy, as a binder material, was considered the best percentage to achieve high performance and to enhance the mechanical stability of Rhizophora particleboards. In conclusion, epoxy resin improves the mechanical and physical properties of Rhizophora spp. particleboards to be performed as a phantom material. [ABSTRACT FROM AUTHOR]

In this study, an inexpensive simple method for the fabrication of efficient hydrogen (H2) gas sensor based on carbon nanotubes (CNTs) was presented. The CNTs were synthesized using microwave oven and deposited onto SiO2 substrate by a dielectrophoretic method. The as-grown CNTs showed an n-type behavior because CNTs possess the characters of both metallic and semiconductor when placed between the two electrodes, meanwhile, the current was directed mostly by metallic tubes. Upon exposure to H2 gas at room temperature, the CNTs exhibited high sensitivity up to 315% at 140 ppm H2, and relatively good sensitivity of 40% at a very low H2 gas concentration of 20 ppm. To the best of our knowledge, this is the first work involving the fabrication of CNTs for detecting a low H2 gas concentration of 20 ppm at RT with high sensitivity comparing with other previous studies. [ABSTRACT FROM AUTHOR]