Tin oxide as an emerging electron transport medium in perovskite solar cells

Electron transport medium (ETM) is one of the most important components determining the photovoltaic performance of organic-inorganic halide perovskite solar cells (PSCs). Among the metal oxide semiconductors, anatase (TiO2) is the most common material used as ETM in PSCs to facilitate charge collection as well as to support a thin perovskite absorber layer. Production of conductive crystalline TiO2 requires relatively higher temperatures (400–500 °C) which limits its application to glass substrates coated with fluorine tin oxide (FTO) as other tin oxides (e.g. indium tin oxide) degrade at temperatures above 300 °C. Furthermore, this renders it unsuitable for flexible devices, often based on low-temperature flexible plastic substrates. Pure tin oxide, one of the earliest metal oxide semiconductors, is often used in myriad electronic devices and has shown outstanding characteristics as an ETM in PSC systems. Thus, tin oxide can be considered a viable alternative to TiO2 due to its excellent electron mobility and higher stability than other alternatives such as zinc oxide. This review article gives a brief history of ETMs in PSC systems and reviews recent developments in the use of tin oxide in both pure and composite form as ETMs. Efficiencies of up to 21% have been reported in tin oxide based PSCs with photovoltages of up to ~1214 mV

Metamorphic Temperature Investigation of Coexisting Calcite and Dolomite Marble––Examples from Nikani Ghar Marble and Nowshera Formation, Peshawar Basin, Pakistan

Using marble samples from the Nikani Ghar marble and Nowshera Formation from Northern Pakistan the determination of the temperature of metamorphism was undertaken with the help of calcite-dolomite solvus geothermometer. Two types of marbles, that is, calcite-dolomite marble and quartz-bearing calcite-dolomite marble were selected. Petrographic and scanning electron microscope analysis of dolomite samples indicated different grain sizes. X-ray diffraction technique indicated the calcites MgCO3 content up to 7.93 mol.%. Nikani Ghar marble samples have shown lower contents of MgCO3 as compared to samples from Nowshera Formation. The calcite-dolomite-quartz marble has also showed relatively lower MgCO3 content and hence rather low temperature (~500 °C). The temperature reached during peak metamorphism of the investigated marble occurrence, based on calcitedolomite solvus was 628 °C. Metamorphic temperatures derived from the present study were shown as a linear graph and values were in good agreement with the published literature

Effect of Fluxing Additive on Sintering Temperature, Microstructure and Properties of BaTiO\u3csub\u3e3\u3c/sub\u3e

Various fluxing materials are added to technical ceramics in an attempt to lower their sintering temperatures and make their processing economical. The effect of 0·3wt% Li2CO3 addition on the phase, microstructure, phase transition temperatures and dielectric properties of BaTiO3 was investigated in the present study. The addition of 0·3wt% Li2CO3 was observed to lower the optimum sintering temperature by ∼200◦C with no second phase formation and cause a five-fold reduction in grain size. Rhombohedral-to-orthorhombic and tetragonal-to-cubic phase transitions at the expected temperatures were evident from the Raman spectra, but the orthorhombic-totetragonal phase transition was not clearly discernible. The persistence of various phase(s) at higher temperatures in the flux-added materials indicated that the phase transitions occurred relatively slowly. A decrease in dielectric constant of Li2O-added BaTiO3 in comparison to pure BaTiO3 may be due to the diminished dielectric polarizability of Li+ in comparison to Ba2+

Unification of the Negative Electrocaloric Effect in Bi\u3csub\u3e1/2\u3c/sub\u3eNa\u3csub\u3e1/2\u3c/sub\u3eTiO\u3csub\u3e3\u3c/sub\u3e-BaTiO\u3csub\u3e3\u3c/sub\u3e Solid Solutions by Ba\u3csub\u3e1/2\u3c/sub\u3eSr\u3csub\u3e1/2\u3c/sub\u3eTiO\u3csub\u3e3\u3c/sub\u3e Doping

The microscopic mechanisms of the negative electrocaloric effect (ECE) of the single-phase (1−x)(0.94Bi1/2Na1/2TiO3-0.06BaTiO3)-xBa1/2Sr1/2TiO3 (BNT-BT-BST) perovskite solid solutions fabricated via the sol-gel technique are explored in this study. Dielectric and mechanical relaxation analyses are employed to investigate the ferroelectric and structural transitions of the samples. The electrocaloric properties of the samples were measured by thermodynamics Maxwell relations. The difference between the depolarization temperature (Td) and the maximum dielectric constant temperature (Tm) was found to decrease with increasing BST content. Doping with BST stabilized the ferroelectric phase along with unifying the EC temperature changes (ΔT) to only negative values. The origin of the uniform negative ECE of BNT-BT-BST is discussed

Do natural disasters affect economic growth? The role of human capital, foreign direct investment, and infrastructure dynamics

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Acute disseminated encephalomyelitis as the first presentation of CNS tuberculosis: report of a case with brief review

Acute disseminated encephalomyelitis (ADEM) also known as post infectious encephalomyelitis is a demyelinating disease of the central nervous system (CNS) that typically presents as a monophasic disorder associated with multifocal neurological symptoms and disability. It may follow vaccination in children or infection. Viral infection like measles, rubella, influenza, Epstein bar, HIV, herpes, cytomegalusvirus (CMV) and West Nile virus have been implicated in the causation. Among bacteria, group A hemolytic streptococcus, mycoplasma pneumonia, Chlamydia, Rickettesia and leptospira have been shown to cause ADEM. There are few reports of ADEM due to tuberculosis (TB). We describe acute disseminated encephalomyelitis due to tuberculosis in a 35 year old female who initially started with neuropsychiatric manifestations and later developed florid neurological deficit and classical magnetic resonance imaging (MRI) lesions suggestive of the disease. The patient recovered completely after antitubercular therapy and is following our clinic for the last 12 months now

Advances in stable and flexible perovskite solar cells

Roll-to-roll (R2R) production is an innovative approach and is fast becoming a very popular industrial method for high throughput and mass production of solar cells. Replacement of costly indium tin oxide (ITO), which conventionally has served as the transparent electrode would be a great approach for roll to roll production of flexible cost effective solar cells. Indium tin oxide (ITO) and fluorine-doped tin oxide (FTO) are brittle and ultimately limit the device flexibility. Perovskite solar cells (PSCs) have been the centre of photovoltaic research community during the recent years owing to its exceptional performance and economical prices. The best reported PSCs fabricated by employing mesoporous TiO2 layers require elevated temperatures in the range of 400–500 °C which limits its applications to solely glass substrates. In such a scenario developing flexible PSCs technology can be considered a suitable and exciting arena from the application point of view, them being flexible, lightweight, portable, and easy to integrate over both small, large and curved surfaces

Awareness to Handle Research and Healthcare Waste (RHCW) in teaching and research institutes; a comprehensive review

Environmental pollution has become the major challenge not only for developing countries but also for developed ones Worldwide. The major goal of this comprehensive review is to compile the reference data regarding the different types of waste generated in teaching, research, and healthcare institutes and specific strategy to manage such wastes. In addition to the pharmaceutical, leather, chemicals, food, and paper industries, teaching, research, and healthcare institutions are also significant sources of different types of Non-hazardous as well as hazardous wastes. Therefore, a simple and implementable guideline for cleaning and waste disposal services in such institutions requires strict adherence to applicable policies and procedures. Research and healthcare waste (RHCW) management is a joint effort among Research Laboratory Personnel, Healthcare facilitators, Building Services Personnel, and Local Environmental Health and Safety Personnel. As Pakistan is among the developing countries situated in South Asia, most of the institutes, including teaching, research, and healthcare, try to follow the WHO guidance or manage hazardous and non-hazardous wastes with self-planned strategies. Although most of the local Governing bodies and Institutional bodies are trying to handle the wastes at their levels by following different protocols, introducing a protocol at the National level is the need of the current era to fight against environmental pollutants.

Chemical composition and pharmacological bio-efficacy of Parrotiopsis jacquemontiana (Decne) Rehder for anticancer activity

Consistent STAT3 (Single transducer and activator of transcription 3) activation is observed in many tumors and promotes malignant cell transformation. In the present investigation, we evaluated the anticancer effects of Parrotiopsis jacquemontiana methanol fraction (PJM) on STAT3 inhibition in HCCLM3 and MDA-MB 231 cells. PJM suppressed the activation of upstream kinases i.e. JAK-1/2 (Janus kinase-1/2), and c-Src (Proto-oncogene tyrosine-protein kinase c-Src), and upregulated the expression levels of PIAS-1/3 (Protein Inhibitor of Activated STATs-1/3), SHP-1/2 (Src-homology region 2 domain-containing phosphatase-1/2), and PTP-1β (Protein tyrosine phosphatase 1 β) which negatively regulate STAT3 signaling pathway. PJM also decreased the levels of protein products conferring to various oncogenes, which in turn repressed the proliferation, migration, invasion, and induced apoptosis in cancer cell lines. The growth inhibitory effects of PJM on cell-cycle and metastasis were correlated with decreased expression levels of CyclinD1, CyclinE, MMP-2 (Matrix metalloproteinases-2), and MMP-9 (Matrix metalloproteinases-9). Induction of apoptosis was indicated by the cleavage and subsequent activation of Caspases (Cysteine-dependent Aspartate-directed Proteases) i.e. caspase-3, 7, 8, 9, and PARP (Poly (ADP-ribose) polymerase) as well as through the down-regulation of anti-apoptotic proteins. These apoptotic effects of PJM were preceded by inhibition of STAT3 cell-signaling pathway. STAT3 was needed for PJM-induced apoptosis, and inhibition of STAT3 via pharmacological inhibitor (Stattic; SC-203282) abolished the apoptotic effects. Conclusively, our results demonstrate the capability of PJM to inhibit cancer cell-proliferation and induce apoptosis by suppressing STAT3 via upregulation of STAT3 inhibitors and pro-apoptotic proteins whereas the down-regulation of upstream kinases and anti-apoptotic protein expression. In future, one-step advance studies of PHM regarding its role in metastatic inhibition, immune response modulation for reducing tumor, and inducing apoptosis in suitable animal models would be an interesting and promising research area