IN A SEARCH FOR LEAD-FREE MATERIALS THAT COULD BE USED AS ALTERNATIVES TO THE HYBRID PEROVSKITES, (MA)PbX 3 , in photovoltaic applications, we have discovered a hybrid double perovskite, (MA) 2 KBiCl 6 , which shows striking similarities to the lead analogues. Spectroscopic measurements and nanoindentation studies are combined with density functional calculations to reveal the properties of this interesting system.The light-harvesting, semiconducting hybrid inorganic-organic perovskites (HIOPs) have recently attracted a great deal of attention in the photovoltaic community, with their solar cell efficiencies rising from ~4% to over 20% in just six years. 1, 2 The most extensively studied materials are the lead-containing systems, APbX 3 , where A is alkyl ammonium cation (e.g. CH 3 NH 3 + (methylammonium, MA) or NH 2 CHNH 2 + (formamidinium, FA)) and X is Cl -, Bror I -. However, the toxicity of lead to the environment could become a major drawback in their commercialization and the quest for lead-free alternatives is therefore attracting a lot of attention. Other group IV metals such as Ge and Sn are being explored, but the chemical instability of Sn 2+ and Ge 2+ presents challenges for their practical utilization. 3,4 Alternatively, the replacement of Pb 2+ by isoelectronic ions also seems attractive because the strong light absorption and long carrier life-times exhibited by MAPbX 3 are believed to be related to the 6s 2 6p 0 electronic configuration of Pb 2+ . 5 While Tl + is also toxic, Bi 3+ is an interesting option because coordination complexes of bismuth are used in over-the-counter medicines such as Pepto-Bismol. 6 However, this strategy poses challenges because Bi 3+ has a different valence state from Pb 2+ and cannot therefore be simply substituted into phases such as (MA)PbX 3 . In the present work, we show that the incorporation of Bi 3+ into a HIOP can be achieved by synthesizing a hybrid double perovskite of general formula (MA) 2 M I M III X 6 .There has been significant recent progress in the incorporation of Bi 3+ into hybrid perovskiterelated halides. For example, (MA) 3 Bi 2 I 9 can be readily obtained by using a synthetic route analogous to that used for MAPbI 3 , 7 and an ammonium bismuth iodide phase, (NH 4 ) 3 Bi 2 I 9 , was recently reported to show a bandgap of 2.04eV. 8 A number of alkali metal systems of

Organic-inorganic halide perovskites, especially methylammonium lead halide, have recently led to a remarkable breakthrough in photovoltaic devices. However, due to the environmental and stability concerns of the heavy metal, lead, in these perovskite based solar cells, research in the non-lead perovskite structures have been attracting increasing attention. In this study, a layered perovskite-like architecture, (NH4)3Bi2I9, was prepared in solution and the structure was solved by single crystal X-ray diffraction. The results from DFT calculations showed the significant lone pair effect of the bismuth ion and the band gap was measured as around 2.04 eV, which is lower than the band gap of CH3NH3PbBr3. Conductivity measurement was also performed to examine the potential in the applications as an alternative to the lead containing perovskites.

Variable liquid crystal pretilt angles of any value from 0 to 90° can be obtained by using a nanostructured alignment layer. This layer is robust and reliable. The pretilt angles obtained are stable against high storage and operating temperatures, and have strong anchoring energies.

Purpose: By using cDNA microarray analysis, we identified a transcriptional factor, SOX6, was frequently downregulated in esophageal squamous cell carcinoma (ESCC). The aim of this study is to investigate the role of SOX6 in human esophageal cancer development, and to examine the prevalence and clinical significance of SOX6 downregulation in ESCC.Experimental Design: Expressions of SOX6 mRNA in 50 ESCCs and SOX6 protein in 300 ESCCs were investigated by semiquantitative RT-PCR and immunohistochemistry, respectively. The tumor-suppressive function of SOX6 was characterized by cell growth, foci formation, wound-healing and cell invasive assays, and tumor xenograft experiment. Western blot analysis was applied to detect protein expression levels.Results: SOX6 was frequently downregulated in primary ESCCs in both mRNA level (29/50, 58%) and protein level (149/219, 68.0%), which was significantly associated with the poor differentiation (P ¼ 0.029), lymph node metastases (P ¼ 0.014), advanced TNM stage (P ¼ 0.000), and disease-specific survival (P < 0.001). Multivariate analysis indicated that the downregulation of SOX6 (P ¼ 0.000) was a significant independent prognostic factors for ESCC. Functional studies showed that SOX6 was able to suppress both in vitro and in vivo tumorigenic ability of ESCC cells. The tumor-suppressive mechanism of SOX6 was associated with its role in G1/S cell-cycle arrest by upregulating expressions of p53 and p21 WAF1/CIP1 and downregulating expressions of cyclin D1/CDK4, cyclin A, and b-catenin. Conclusions:We provided the first evidence that SOX6 is a novel tumor-suppressor gene in ESCC development and is a potential prognostic marker in ESCC.

Loss of chromosome 19p is one of the most frequent allelic imbalances in esophageal squamous cell carcinoma (ESCC), suggesting the existence of one or more tumor suppressor genes within this region. In this study, we investigated a role in ESCCs for a candidate tumor suppressor gene located at 19p13.3, the Ras-like small GTPase DIRAS1. Downregulation of DIRAS1 occurred in approximately 50% of primary ESCCs where it was associated significantly with advanced clinical stage, lymph node metastasis, and poor overall survival. LOH and promoter methylation analyses suggested that loss of DIRAS1 expression was mediated by epigenetic mechanisms. Functional studies established that ectopic re-expression of DIRAS1 in ESCC cells inhibited cell proliferation, clonogenicity, cell motility, and tumor formation. Mechanistic investigations suggested that DIRAS1 acted through extracellular signal-regulated kinase (ERK1/2; MAPK3/1) and p38 mitogen-activated protein kinase (MAPK; MAPK14) signaling to trigger BAD Ser112 dephosphorylation and matrix metalloproteinase (MMP)2/9 transcriptional inactivation to promote apoptosis and inhibit metastasis, respectively. Taken together, our results revealed that DIRAS1 has a pivotal function in ESCC pathogenesis, with possible use as a biomarker and intervention point for new therapeutic strategies. Cancer Res; 73(7); 2298-309. Ó2013 AACR.

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