Perovskite-Structured Photovoltaic Materials

In this chapter, we provide the historical background and overview of perovskite-structured photovoltaic materials. The organolead halide perovskite-structured solar cell is considered as one of the most promising photovoltaic technologies due to its rapid progress in power conversion efficiency. However, the existence of lead in perovskite-structured photovoltaic materials raises toxicological and environmental issues. Therefore, many scientists focused on discovering new materials that can replace the lead and improve photovoltaic performance. There are still some issues to be overcome before commercialization of perovskite-structured photovoltaic materials. The fast degradation phenomenon under humidity or constant irradiation is one such issue. The hysteresis phenomena could cause inaccurate estimation of power conversion efficiency. The choice of selective contact also plays an important role in obtaining high performance device. Therefore, the interaction between each layer should be considered. Overall, we reported on state-of-the-art perovskite-structured photovoltaic materials and discussed the essential factor for fabricating high-performance perovskite-structured solar cells

Mechanisms of Visible Light Photocatalysis in N-Doped Anatase TiO2 with Oxygen Vacancies from GGA+U Calculations

We have systematically studied the photocatalytic mechanisms of nitrogen doping in anatase TiO2 using first-principles calculations based on density functional theory, employing Hubbard U (8.47 eV) on-site correction. The impurity formation energy, charge density, and electronic structure properties of TiO2 supercells containing substitutional nitrogen, interstitial nitrogen, or oxygen vacancies were evaluated to clarify the mechanisms under visible light. According to the formation energy, a substitutional N atom is better formed than an interstitial N atom, and the formation of an oxygen vacancy in N-doped TiO2 is easier than that in pure TiO2. The calculated results have shown that a significant band gap narrowing may only occur in heavy nitrogen doping. With light nitrogen doping, the photocatalysis under visible light relies on N-isolated impurity states. Oxygen vacancies existence in N-doped TiO2 can improve the photocatalysis in visible light because of a band gap narrowing and n-type donor states. These findings provide a reasonable explanation of the mechanisms of visible light photocatalysis in N-doped TiO2

High-Performance Perovskite Solar Cells Based on Low-Temperature Processed Electron Extraction Layer

Organic-inorganic perovskite solar cells (PSCs) is considered one of the most promising energy harvesting technologies due to its high power conversion efficiency (PCE). The T. Miyasaka group first reported the methylammonium lead halide (CH3NH3PbX3) as a light absorber of dye-sensitized solar cells with a PCE of 3.8% in 2009. Over the past decade, many research groups have been dedicated to constructing high-performance PSCs and have obtained fantastic progress. Before commercialization, many issues have to be overcome. To extend the application of PSCs, flexible PSCs are seen as the preferred choice. However, the conventional process requires high-temperature procedures that are incompatible with the production of flexible PSCs. Here, we specifically focus on the recent developments of the low-temperature process strategies for fabricating high-performance PSCs. This mini-review briefly discusses the development in low-temperature processed metal oxide and carbon-based electron extraction layer (EEL). The approaches for low-temperature solution-processed PSCs are introduced and then the various PSCs with distinctive EEL are discussed. Overall, this mini-review contributes to a better understanding of the low-temperature processed electron extraction layer. Strategies and perspectives are also provided for further high-performance PSCs

THE EFFECTS OF EXTERNAL LOAD ON LOWER EXTREMiTY ELECTROMYOGRAPHY AMPLITUDE DURING COUNTERMOVEMENT JUMP

The purpose of this study was to investigate the effects of different loads on the mean electromyography (EMG) amplitude of the gluteus maximus, biceps fernoris, vastus medialis, gastrocnemius, soleus, and tibialis anterior during the deceleration phase and the acceleration phase of the countermovement jumps (CMJ). Ten male physical education students performed different CMJs with and without an external load (0,2.5,5.0, 7.5, or 10.0 kg hold in arms). The results s h o w the amplitude of the gluteus maximus with load of 7.5 kg was higher than with load of 2.5 kg during the deceleration phase (p < .05), and the amplitude of the soleus with load of 10.0 kg was higher than with load of 2.5 kg during the acceleration phase (p < .05). It indicated that the activities of lower limb muscles were not influenced by the relative lower of external loading during CMJ

Signal transducer and activator of transcription 3 activation up-regulates interleukin-6 autocrine production: a biochemical and genetic study of established cancer cell lines and clinical isolated human cancer cells

<p>Abstract</p> <p>Background</p> <p>Spontaneous interleukin-6 (IL-6) production has been observed in various tumors and implicated in the pathogenesis, progression and drug resistance in cancer. However, the regulation of IL-6 autocrine production in cancer cells is not fully understood. IL-6 is auto-regulated in many types of cell. Two of the three major downstream pathways of IL-6, MEK/extracellular signal-related kinase (Erk) pathway and phosphatidylinositol 3-kinase (PI3-K)/Akt pathway, have been shown to regulate IL-6 expression through the activation of AP-1 and NF-κB. However, it is not clear what the role of Janus kinase (Jak) 2/signal transducer and activator of transcription (Stat) 3 pathway. This study was designed to determine the role of Jak2/Stat3 pathway in the regulation of IL-6 autocrine production in cancer cells.</p> <p>Results</p> <p>Inhibitors of Jak2/Stat3, MEK/Erk and PI3-K/Akt pathways down-regulated IL-6 secretion in the lung adenocarcinoma PC14PE6/AS2 (AS2) cells, which spontaneously secreted IL-6 and possessed constitutively activated Stat3. Transfection with dominant-negative Stat3, Stat3 siRNA, or Stat3 shRNA decreased IL-6 expression in AS2 cells. Conversely, transfection with constitutively-activated Stat3 increased the production of IL-6. In AS2 derived cells, resistance to paclitaxel was positively correlated with Stat3 activation status and the expression of IL-6, which is commonly secreted in drug resistant cancer cells. The pharmacological inhibition of NF-κB, PI3-K/Akt and MEK/Erk and the pharmacological inhibition and genetic inhibition (Stat3 siRNA) of Jak2/Stat3 pathway decreased IL-6 autocrine production in various drug resistant cancer cell lines and similarly decreased IL-6 autocrine production in clinically isolated lung cancer cells.</p> <p>Conclusions</p> <p>This study is the first to directly address the role Stat3 plays on the autocrine production of IL-6, which occurs through a positive-feedback loop. Our biochemical and genetic studies clearly demonstrated that Jak2/Stat3, in combination with other IL-6 downstream pathways, contributed frequently and substantially to IL-6 autocrine production in a broad spectrum of cancer cell lines as well as in clinical cancer samples. Our findings suggest that Stat3 could potentially be regulated to suppress IL-6 autocrine production in cancer cells to inhibit the progression of cancer and reduce drug resistance.</p

Signal transducer and activator of transcription 3 activation up-regulates interleukin-6 autocrine production: a biochemical and genetic study of established cancer cell lines and clinical isolated human cancer cells

<p>Abstract</p> <p>Background</p> <p>Spontaneous interleukin-6 (IL-6) production has been observed in various tumors and implicated in the pathogenesis, progression and drug resistance in cancer. However, the regulation of IL-6 autocrine production in cancer cells is not fully understood. IL-6 is auto-regulated in many types of cell. Two of the three major downstream pathways of IL-6, MEK/extracellular signal-related kinase (Erk) pathway and phosphatidylinositol 3-kinase (PI3-K)/Akt pathway, have been shown to regulate IL-6 expression through the activation of AP-1 and NF-κB. However, it is not clear what the role of Janus kinase (Jak) 2/signal transducer and activator of transcription (Stat) 3 pathway. This study was designed to determine the role of Jak2/Stat3 pathway in the regulation of IL-6 autocrine production in cancer cells.</p> <p>Results</p> <p>Inhibitors of Jak2/Stat3, MEK/Erk and PI3-K/Akt pathways down-regulated IL-6 secretion in the lung adenocarcinoma PC14PE6/AS2 (AS2) cells, which spontaneously secreted IL-6 and possessed constitutively activated Stat3. Transfection with dominant-negative Stat3, Stat3 siRNA, or Stat3 shRNA decreased IL-6 expression in AS2 cells. Conversely, transfection with constitutively-activated Stat3 increased the production of IL-6. In AS2 derived cells, resistance to paclitaxel was positively correlated with Stat3 activation status and the expression of IL-6, which is commonly secreted in drug resistant cancer cells. The pharmacological inhibition of NF-κB, PI3-K/Akt and MEK/Erk and the pharmacological inhibition and genetic inhibition (Stat3 siRNA) of Jak2/Stat3 pathway decreased IL-6 autocrine production in various drug resistant cancer cell lines and similarly decreased IL-6 autocrine production in clinically isolated lung cancer cells.</p> <p>Conclusions</p> <p>This study is the first to directly address the role Stat3 plays on the autocrine production of IL-6, which occurs through a positive-feedback loop. Our biochemical and genetic studies clearly demonstrated that Jak2/Stat3, in combination with other IL-6 downstream pathways, contributed frequently and substantially to IL-6 autocrine production in a broad spectrum of cancer cell lines as well as in clinical cancer samples. Our findings suggest that Stat3 could potentially be regulated to suppress IL-6 autocrine production in cancer cells to inhibit the progression of cancer and reduce drug resistance.</p

The Untranslated Regions of Classic Swine Fever Virus RNA Trigger Apoptosis

Classical swine fever virus (CSFV) causes a broad range of disease in pigs, from acute symptoms including high fever and hemorrhages, to chronic disease or unapparent infection, depending on the virus strain. CSFV belongs to the genus Pestivirus of the family Flaviviridae. It carries a single-stranded positive-sense RNA genome. An internal ribosomal entry site (IRES) in the 5' untranslated region (UTR) drives the translation of a single open reading frame encoding a 3898 amino acid long polypeptide chain. The open reading frame is followed by a 3' UTR comprising four highly structured stem-loops. In the present study, a synthetic RNA composed of the 5' and 3' UTRs of the CSFV genome devoid of any viral coding sequence and separated by a luciferase gene cassette (designated 5'UTR-Luc-3'UTR) triggered apoptotic cell death as early as 4 h post-transfection. The apoptosis was measured by DNA laddering analysis, TUNEL assay, annexin-V binding determined by flow cytometry, and by analysis of caspase activation. Contrasting with this, only trace DNA laddering was observed in cells transfected with the individual 5' or 3' UTR RNA; even when the 5' UTR and 3' UTR were co-transfected as separate RNA molecules, DNA laddering did not reach the level induced by the chimeric 5'UTR-Luc-3'UTR RNA. Interestingly, RNA composed of the 5'UTR and of stem-loop I of the 3'UTR triggered much stronger apoptosis than the 5' or 3'UTR alone. These results indicate that the 5' and 3' UTRs act together in cis induce apoptosis. We furthered obtained evidence that the UTR-mediated apoptosis required double-stranded RNA and involved translation shutoff possibly through activation of PKR