Effects of Structure and Morphology of Hydrothermally Grown ZnO Particles on the Photovoltaic Performance of Dye Sensitized Solar Cell

Highly ordered microporous ZnO materials with crystalline structure were synthesized hydrothermally from three different Zn-precursorsnamely: Zinc-acetate, chloride, and nitrate. XRD investigations revealed that all the obtained powders have single phase zincite structure. The powder morphology was investigated by SEM which showed that the starting Zn-precursor affects the shape as well as the size of the obtained particles. A photoelectrodes fabricated using the three different synthesized microporous ZnO particles showed variation in photocurrent density (Jsc) dye loading and hence the efficiency with variation in structure texture, morphology and particle size. DSSC built with photoelectrodes made from Zn-acetate has the highest efficiency (5.4%) which is attributed to having lowest particle size and largest surface area available for dye loading. This increases light harvesting at the photoelectrode which in turn increases short circuit current density. On the other hand, the lowest current density (5.65mA/cm2) is obtained for DSSC with photolelctrodes made from Zn-nitrate

Synthesis and characterization of aluminum doped zinc oxide nanostructures via hydrothermal route

Stable crystalline aluminum doped zinc oxide (AZO) nanopowders were synthesized using hydrothermal treatment processing. Three different aluminum precursors have been used. The Al-precursors were found to affect the morphology of the obtained nanopowders. AZO nanoparticles based on zinc acetate and aluminum nitrate have been prepared with different Al/Zn molar ratios. XRD investigations revealed that all the obtained powders have single phase zincite structure with purity of about 99%. The effect of aluminum doping ratio in AZO nanoparticles (based on Al-nitrate precursor) on structure, phase composition, and particle size has been investigated. The incorporation of Al in ZnO was confirmed by UV-Vis spectroscopy revealing a blue shift due to Burstein-Moss effect

Nanoplasmonic for Solar Energy Conversion Devices

The effect of nanoplasmonic (Ag) on the performance of DSSCs has been studied in doped and undoped ZnO (DZ and UZ) NPs, which were prepared by the urea-assisted combustion route. Different techniques were conducted to characterize DZ and UZ NPs. XRD patterns were indexed to the hexagonal wurtzite structure of ZnO NPs (ICSD-52362). The values of average crystalline size of UZ and DZ (1.0 mol% Ag) NPs were 20.45 and 22.30 nm, respectively. HR-TEM micrograph revealed good crystallization with an intermediate or poor agglomeration with distribution of semispherical morphologies of ZnO NPs. The energy bandgap of UZ and DZ NPs was changed from 3.21 to 3.31 eV. The deconvolution of the PL spectra recognized eight peaks into near ultraviolet (NUV) and visible regions. The PL emission of visible region overshadowed NUV transition. The photovoltaic cell with the doped photoanode DZ:1.0 mol% Ag exhibited the best performance parameters: Voc = 0.46 V, Jsc = 7.81 mA.cm−2, Pm = 1.91, FF = 51%, and η = 1.91%. A double exponential function was used as a powerful fitting function for the TOCVD data. The results revealed that τn in the UZ NPs photoanode was longer than that in the DZ:1.0 mol% Ag NPs photoanode

Origanum syriacum L. Attenuates the Malignant Phenotype of MDA-MB231 Breast Cancer Cells

Breast cancer is the leading cause of cancer-related deaths among women. Among breast cancer types, triple negative breast cancer (TNBC) is the most aggressive, and is resistant to hormonal and chemotherapeutic treatments. As such, alternative approaches that may provide some benefit in fighting this debilitating pathology are critically needed; hence the utilization of herbal medicine. Origanum syriacum L., one of the most regularly consumed plants in the Mediterranean region, exhibits antiproliferative effect on several cancer cell lines. However, whether this herb modulates the malignant phenotype of TNBC remains poorly investigated. Here, we show that in MDA-MB-231, a TNBC cell line, Origanum syriacum L. aqueous extract (OSE) inhibited cellular viability, induced autophagy determined by the accumulation of lipidized LC3 II, and triggered apoptosis. We also show that OSE significantly promoted homotypic cell-cell adhesion while it decreased cellular migration, adhesion to fibronectin, and invasion of MDA-MB-231 cells. This was supported by decreased activity of focal adhesion kinase (FAK), reduced α2 integrin expression, and downregulation of secreted PgE2, MMP2 and MMP-9, in OSE-treated cells. Finally, we also show that OSE significantly inhibited angiogenesis and downregulated the level of nitric oxide (NO) production. Our findings demonstrate the ability of OSE to attenuate the malignant phenotype of the MDA-MB-231 cells, thus presenting Origanum syriacum L. as a promising potential source for therapeutic compounds for TNBC

Anti-proliferative and Anti-metastatic Effect of Aqueous Extract of Origanum Syriacum on Aggressive Human Breast Cancer Cells

Around the world as well as in Qatar, breast cancer is characterized among the highest rates of mortalities that are cancer related. Alarmingly, statistics have shown that the incidence of breast cancer is slightly higher in Qatari women than other Arab countries in the region. This evidence suggests the importance of focusing research on understanding and treatment of breast cancer in Qatar. Current treatment options for breast cancer includes; chemotherapy, surgery, and radiotherapy. Chemotherapy and radiotherapy are associated with undesired side effects; thus, many people tend to look for alternative treatments. Herbal treatments have been used as an alternative to traditional cancer therapies in recent years. Several studies have shown that herbs contain bioactive compounds, including flavonoids, steroids, as well as others, which exert anti-oxidative, anti-proliferative, and anti-inflammatory properties. One of the most commonly used herbs in the Arabian Gulf region is Origanum syriacum. It is known to have anti-oxidative effect. Unfortunately, studies are extremely limited in terms of understanding its anti-carcinogenic effect. Therefore, this study was carried out to determine the effect of O. syriacum aqueous extract (OSE) on an aggressive type of breast cancer (MDA-MB-231) cells. O. syriacum extract was prepared by dissolving the ground dried leaves in water and then drying it using a rotarvapor. Viability of MDA-MB-231 cells in the presence or absence of increasing concentration of OSE was examined by MTT assay. The flow cytometry was used to test the cell cycle progression in the presence of OSE. Moreover, the migratory capacity of MDA-MB-231 cells was determined by Boyden chamber and scratch assay. The invasiveness of MDA-MB-231 in the absence and presence of OSE was investigated using the Matrigel coated wells. Furthermore, adherence of MDA-MB-231 cells to fibronectin was tested with and without OSE. The oxidative stress of the different concentrations of OSE against MDA-MB-231 was determined using ROS-glo assay. Finally, western blot analysis was performed to test the metastatic ability (occludin expression) as well as autophagy marker (LC3A/B expression). The results indicated that OSE decreased the proliferation of MDA-MB-231 cells in a time and a concentration dependent manner. The highest anti-proliferative effects of OSE were observed at concentrations of 0.8 mg/ml and above after 24, 48 and 72 hrs of exposure. Furthermore, OSE arrested cells in G1 phase of cell cycle. Also, migratory capacity of MDA-MB-231 cells declined in the presence of OSE at a concentration of 1.2 mg/ml. Moreover, OSE inhibited the adhesive property along with the invasiveness of aggressive breast cancer cell line. Supporting the above results, an increase in occludin expression was observed in cells treated with OSE indicating that O. syriacum extract has an anti-metastatic capacity. Additionally, the production of ROS as well as the expression of LC3A/B proteins increased in MDA-MB-231 cells treated with OSE at concentration of 1.2 mg/ml. Our results demonstrate that Origanum syriacum may have a potential to be used as a supplemental therapy for patients suffering from malignant breast cancer. Further insight into understanding molecular mechanisms and safety of OSE using in vivo studies should be carried out to fully understand its activity at the molecular level and determine its safe use in the treatment/prevention of breast cancer.qscienc

Characteristics and outcomes of COVID-19 patients admitted to hospital with and without respiratory symptoms

Background: COVID-19 is primarily known as a respiratory illness; however, many patients present to hospital without respiratory symptoms. The association between non-respiratory presentations of COVID-19 and outcomes remains unclear. We investigated risk factors and clinical outcomes in patients with no respiratory symptoms (NRS) and respiratory symptoms (RS) at hospital admission. Methods: This study describes clinical features, physiological parameters, and outcomes of hospitalised COVID-19 patients, stratified by the presence or absence of respiratory symptoms at hospital admission. RS patients had one or more of: cough, shortness of breath, sore throat, runny nose or wheezing; while NRS patients did not. Results: Of 178,640 patients in the study, 86.4 % presented with RS, while 13.6 % had NRS. NRS patients were older (median age: NRS: 74 vs RS: 65) and less likely to be admitted to the ICU (NRS: 36.7 % vs RS: 37.5 %). NRS patients had a higher crude in-hospital case-fatality ratio (NRS 41.1 % vs. RS 32.0 %), but a lower risk of death after adjusting for confounders (HR 0.88 [0.83-0.93]). Conclusion: Approximately one in seven COVID-19 patients presented at hospital admission without respiratory symptoms. These patients were older, had lower ICU admission rates, and had a lower risk of in-hospital mortality after adjusting for confounders