No abstract

Raman microspectroscopy was applied to monitor the intracellular redox state of myoglobin and cytochrome c from isolated adult rat cardiomyocytes during hypoxia and reoxygenation. The nitrite reductase activity of myoglobin leads to the production of nitric oxide in cells under hypoxic conditions, which is linked to the inhibition of mitochondrial respiration. In this work, the subsequent reoxygenation of cells after hypoxia is shown to lead to increased levels of oxygen-bound myoglobin relative to the initial levels observed under normoxic conditions. Increased levels of reduced cytochrome c in ex vivo cells are also observed during hypoxia and reoxygenation by Raman microspectroscopy. The cellular response to reoxygenation differed dramatically depending on the method used in the preceding step to create hypoxic conditions in the cell suspension, where a chemical agent, sodium dithionite, leads to reduction of cytochromes in addition to removal of dissolved oxygen, and bubbling-N 2 gas leads to displacement of dissolved oxygen only. These results have an impact on the assessment of experimental simulations of hypoxia in cells. The spectroscopic technique employed in this work will be used in the future as an analytical method to monitor the effects of varying levels of oxygen and nutrients supplied to cardiomyocytes during either the preconditioning of cells or the reperfusion of ischaemic tissue.

Herein, the optoelectrical investigation of cadmium zinc telluride (CZT) and indium (In) doped CZT (InCZT) single crystals-based photodetectors have been demonstrated. The grown crystals were configured into photodetector devices and recorded the current-voltage ( I-V ) and current-time ( I-t ) characteristics under different illumination intensities. It has been observed that the photocurrent generation mechanism in both photodetector devices is dominantly driven by a photogating effect. The CZT photodetector exhibits stable and reversible device performances to 632 nm light, including a promotable responsivity of 0.38 AW −1 , a high photoswitch ratio of 152, specific detectivity of 6.30 × 10 11 Jones, and fast switching time (rise time of 210 ms and decay time of 150 ms). When doped with In, the responsivity of device increases to 0.50 AW −1 , photoswitch ratio decrease to 10, specific detectivity decrease to 1.80 × 10 11 Jones, rise time decrease to 140 ms and decay time increase to 200 ms. Moreover, these devices show a very high external quantum efficiency of 200% for CZT and 250% for InCZT. These results demonstrate that the CZT based crystals have great potential for visible light photodetector applications.

paved the way for new formulations by the means of compositional engineering of perovskites. [1] Tweaking of halide anion and/or organic cation allowed to push the efficiency as well as stability. [2] Power conversion efficiencies as high as 25.2% have been reported at laboratory scale, [3] which is on par with other matured thin film photovoltaics (PV) technologies. The realization of perovskite for PV application was due to its intriguing optoelectrical properties, which led to its exploitation in other optoelectrical devices such as lasing, [4] X-ray, OLEDs, [5] and photodiodes. [6] Despite its unparalleled performance, the perovskites solar cells (PSCs) suffer from several key issues such as anomalous J-V hysteresis, electrical instability, nonradiative recombination losses, and environmental instability. The primary cause for J-V hysteresis is intrinsic defects present in the perovskites layers and charge accumulation at interfaces. [7][8][9][10] The plausible reason for the charge accumulation at the interface can be unbalanced electron and hole mobility which allows charge to be accumulated at the perovskite/electron selective contact (ESC) and perovskite/hole selective contact (HSC) interface. [11] In the past we have reported unbalance charge extraction along with its charge injection on time scale and noted charge accumulation at ESC/perovskite interface. [12] The defect states present in the bulk of perovskite effect the charge accumulation near the interface. Furthermore, the presence of defects in the bulk of perovskites further acts as trapping center for charge carriers, which in turn causes nonradiative losses and decreases charge carrier's lifetimes leading to deterioration in the device performance. Moreover, the presence of inorganic part suggests mixed conductivity, with contribution from both electronic and ionic conductivity. The ion migration was also speculated to be one of the reason for low long-term PV behavior under stress condition or at V oc . [13,14] Similarly cathode materials such as silver or gold were reported to be found at anode side, which travelled all the way through hole transport materials and perovskites. This diffusion of metallic contact into the active material is a loss and this process can activate intensely by thermal process. [15] Apart from all these, the undesirable process in which dopant ions mainly Li + (used in HSC) can diffuse The electron and hole selective contact (SC) plays a pivotal role in the performance of perovskite solar cells. In order to separate the interfacial phenomenon from bulk, the influence of charge SC is elucidated, by means of impedance spectroscopy. The specific role played by TiO 2 and Spiro-OMeTAD as electron and hole SC in perovskite solar cells is investigated at short circuit condition at different temperatures. The methylammonium lead triiodide (MAPbI 3 ) and mixed perovskite of formamidinium lead iodide and methylammonium lead bromide namely; (FAPbI 3 ) 0.85 (MAPbBr 3 ) 0.15 are probed and parameters such as charge carrier mobi...

An aluminum oxide, Al2O3, template is prepared using a novel Ni imprinting method with high hexagonal pore accuracy and order. The pore diameter after the widening process is about 320 nm. TiO2 layer is deposited inside the template using atomic layer deposition (ALD) followed by the deposition of 6 nm TiN thin film over the TiO2 using a direct current (DC) sputtering unit. The prepared nanotubular TiN/TiO2/Al2O3 was fully characterized using different analytical tools such as X-ray diffraction (XRD), Energy-dispersive X-ray (EDX) spectroscopy, scanning electron microscopy (SEM), and optical UV-Vis spectroscopy. Exploring the current-voltage relationships under different light intensities, wavelengths, and temperatures was used to investigate the electrode’s application before and after Au coating for H2 production from sewage water splitting without the use of any sacrificing agents. All thermodynamic parameters were determined, as well as quantum efficiency (QE) and incident photon to current conversion efficiency (IPCE). The QE was 0.25% and 0.34% at 400 mW·cm−2 for the photoelectrode before and after Au coating, respectively. Also, the activation energy was 27.22 and 18.84 kJ·mol−1, the enthalpy was 24.26 and 15.77 J·mol−1, and the entropy was 238.1 and 211.5 kJ−1·mol−1 before and after Au coating, respectively. Because of its high stability and low cost, the prepared photoelectrode may be suitable for industrial applications.