Studies on the effect of sodium arsenate & cadmium chloride on Pithophora oedogonia (Mont.) Wittrock 1877

Cadmium and Arsenic are heavy metals although not common in our environment, its threat in certain places are aggravated due to anthropogenic factors. To know its critical role on plants the investigation was made using Na2HAsO4 and CdCl2 treatment on Pithophora oedogonia (Mont.) Wittrock 1877. The observations were made after 14 days of treatment. The changes were noted. In both cases, the treated cells exhibited gradual disruption of cell wall and cell membrane. The chlorophyll content initially increased and finally decreased due to the notable destruction of chloroplasts in both treated cells. A profuse number of akinetes were observed at 100 ppm and 150 ppm of Na2HAsO4 and CdCl2 treated media. Decrease in protein content was started at 100 ppm in both cases. The lipid content initially decreased at 50 ppm and at 100 ppm lipid profile increased in terms of toleration to the Na2HAsO4 and CdCl2 stress. Pithophora oedogonia (Mont.) Wittrock 1877 exhibited more sensitivity to CdCl2 stress & showing abrupt changes in chlorophyll-a and chlorophyll-b production. The carotenoid production shown more sensitivity in Na2HAsO4 stress. Total phenol production was decreased initially and at 200 ppm CdCl2 stress had shown significant enhancement than the control set but at the 200 ppm of Na2HAsO4 shown inhibitory effect.

Impact of CdCl2 Treatment in CdTe Thin Film Grown on Ultra-Thin Glass Substrate via Close Spaced Sublimation

In this study, close-spaced sublimation (CSS) grown cadmium telluride (CdTe) thin films with good adhesion to 100 µm thin Schott D263T ultra-thin glass (UTG) were investigated. Cadmium chloride (CdCl2) treatment in vacuum ambient was executed to enhance the film quality and optoelectrical properties of CdTe thin film. The post-deposition annealing temperature ranging from 360–420 °C was examined to improve the CdTe film quality on UTG substrate. Various characterization techniques have been used to observe the compositional, morphological, optical, as well as electrical properties. Scanning electron microscopy (SEM) verified that the CdTe morphology and grain size could be controlled via CdCl2 treatment temperature. Energy Dispersive X-Ray Analysis (EDX) results confirmed that the annealing temperature range of 375–390 °C yielded the stoichiometric CdTe films. UV-Vis analysis estimated the post-treatment bandgap energy in the range of 1.39–1.46 eV. Carrier concentration and resistivity were obtained in the order of 1013 cm−3 and 104 Ω-cm, respectively. All the experimental results established that the CdCl2 treatment temperature range of 390–405 °C might be considered as the optimum process temperature for the deposition of CdTe solar cell on UTG substrate in close-spaced sublimation (CSS) method.

Incorporation of CdCl2 surface treatment into the CdS/ZnTe hetero-junction solar cell device structures for efficiency improvement

p-ZnTe thin film semiconductors have been successfully used as an absorber material to n-CdS window layer by effectively optimising the ZnTe absorber layer thickness. In order to create a two terminal hetero-junction diode from the n- and p- type materials, two ohmic electrical contacts are required. This was achieved by depositing n-CdS layers on glass/fluorine-doped tin oxide (FTO) conducting substrate and evaporating Au on p-ZnTe layer. The ZnTe layer was successfully electroplated on CdS thin film grown on glass/fluorine-doped tin oxide (FTO) conducting substrates. The device structures were subjected to heat treatment in air with and without CdCl2 surface treatment using temperature of 400oC and duration of 10 minutes. The incorporation of the CdCl2 treatment led to enhancement in the solar cell efficiency. Solar cells developed from glass/FTO/n-CdS/p-ZnTe/Au device structure gave an open circuit voltage (Voc) of 450 mV, short circuit current density (Jsc) of 7.26 mAcm-2 and fill-factor (FF) of 0.31 resulting in 1.0% efficiency (η) for n-CdS/p-ZnTe heterostructure annealed ordinarily in air. After treating the top surface of n-CdS/p-ZnTe heterostructure with CdCl2 solution, all the solar cell parameters improved with Voc of 480 mV, Jsc of 24.0 mAcm-2 and FF of 0.46 giving a total efficiency of 5.3%. For the CdS/ZnTe heterostructures treated without and with CdCl2 solution, the rectification factors (RF) observed from the I-V characteristics under dark condition for these devices are 101.0 and 102.2 respectively. Both devices show ideality factors (n) in excess of 2.0 and the reverse saturation currents are 79.4 and 0.16 nA for hetero-junction structures without and with CdCl2 treatment respectively. The improvement in the solar cell efficiency can be accredited to the integration of the CdCl2 treatment in the p-n junction cells. Keywords: Solar Cells, p-n Junction Diodes, n-CdS, Heterostructure, p-ZnTe, CdCl2 surface treatment.

Annealing and surface treatment effect on the optical and electrical properties of n-type CdS binary compound semiconductors

The preparation of CdS thin films were actualised with electrodeposition technique using cathodic voltage of 1200 milli – Volts (mV). The optical and electrical properties of three different classes of CdS semiconductors namely as – deposited CdS layers (AD-CdS), CdS layers heat-treated in air without any chemical treatment (HT-CdS) and CdS layers treated with CdCl2 and annealed in air (CC-CdS) have been investigated in this work. Results from optical analysis showed that AD-CdS layers have the least absorption edge and highest energy bandgap. Annealing the CdS thin films without and with CdCl2 treatment brings the energy bandgap to same value of ~2.42 eV. The main distinction between the HT- and CC-CdS layers is that the absorption edge of CC-CdS films is sharper than the HT-CdS. Results from electrical analysis revealed that the magnitude of photo-electro-chemical (PEC) cell signals which give a clue about the doping concentration of the semiconductor material is greater in CC-CdS layers than in AD- and HT-CdS layers.Keywords: AD-CdS, HT-CdS, CC-CdS, Energy Bandgap, Absorption Edge, PEC Cell Signal.

Carnosic Acid Attenuates Cadmium Induced Nephrotoxicity by Inhibiting Oxidative Stress, Promoting Nrf2/HO-1 Signalling and Impairing TGF-β1/Smad/Collagen IV Signalling

Cadmium (Cd) imparts nephrotoxicity via triggering oxidative stress and pathological signal transductions in renal cells. The present study was performed to explore the protective mechanism of carnosic acid (CA), a naturally occurring antioxidant compound, against cadmium chloride (CdCl2)-provoked nephrotoxicity employing suitable in vitro and in vivo assays. CA (5 µM) exhibited an anti-apoptotic effect against CdCl2 (40 µM) in normal kidney epithelial (NKE) cells evidenced from cell viability, image, and flow cytometry assays. In this study, CdCl2 treatment enhanced oxidative stress by triggering free radical production, suppressing the endogenous redox defence system, and inhibiting nuclear factor erythroid 2-related factor 2 (Nrf2) activation in NKE cells and mouse kidneys. Moreover, CdCl2 treatment significantly endorsed apoptosis and fibrosis via activation of apoptotic and transforming growth factor (TGF)-β1/mothers against decapentaplegic homolog (Smad)/collagen IV signalling pathways, respectively. In contrast, CA treatment significantly attenuated Cd-provoked nephrotoxicity via inhibiting free radicals, endorsing redox defence, suppressing apoptosis, and inhibiting fibrosis in renal cells in both in vitro and in vivo systems. In addition, CA treatment significantly (p < 0.05–0.01) restored blood and urine parameters to near-normal levels in mice. Histological findings further confirmed the protective role of CA against Cd-mediated nephrotoxicity. Molecular docking predicted possible interactions between CA and Nrf2/TGF-β1/Smad/collagen IV. Hence, CA was found to be a potential therapeutic agent to treat Cd-mediated nephrotoxicity.

PL Study on the Effect of Cu on the Front Side Luminescence of CdTe/CdS Solar Cells

The effect of Cu on highly efficient CdTe thin solid film cells with a glass/TCO/CdS/CdTe structure subjected to CdCl2 treatment was investigated by low-temperature photoluminescence (PL). The PL of the CdS/CdTe junction in samples without Cu deposition revealed a large shift in the bound exciton position due to the formation of CdSxTe1−x alloys with Eg (alloy) ≅ 1.557 eV at the interface region. After Cu deposition on the CdTe layer and subsequent heat treatment, a neutral acceptor-bound exciton (A0Cu,X) line at 1.59 eV and two additional band-edge peaks at 1.54 and 1.56 eV were observed, indicating an increase in the energy gap value in the vicinity of the CdTe/CdS interface to that characteristic of bulk CdTe. These results may suggest the disappearance of the intermixing phase at the CdTe/CdS interface due to the presence of Cu atoms in the junction area and the interaction of the Cu with sulfur atoms. Furthermore, an increase in the intensity of CdS-related peaks in Cu-doped samples was observed, implying that Cu atoms were incorporated into CdS after heat treatment.