Enhanced control of self-doping in halide perovskites for improved thermoelectric performance

Metal halide perovskites have emerged as promising photovoltaic materials, but, despite ultralow thermal conductivity, progress on developing them for thermoelectrics has been limited. Here, we report the thermoelectric properties of all-inorganic tin based perovskites with enhanced air stability. Fine tuning the thermoelectric properties of the films is achieved by self-doping through the oxidation of tin (ΙΙ) to tin (ΙV) in a thin surface-layer that transfers charge to the bulk. This separates the doping defects from the transport region, enabling enhanced electrical conductivity. We show that this arises due to a chlorine-rich surface layer that acts simultaneously as the source of free charges and a sacrificial layer protecting the bulk from oxidation. Moreover, we achieve a figure-of-merit (ZT) of 0.14 ± 0.01 when chlorine-doping and degree of the oxidation are optimised in tandem

20(S)-25-methoxyl-dammarane-3β, 12β, 20-triol, a novel natural product for prostate cancer therapy: activity in vitro and in vivo and mechanisms of action

We recently isolated 20(S)-25-methoxyl-dammarane-3β, 12β, 20-triol (25-OCH3-PPD), a natural product from Panax notoginseng, and demonstrated its cytotoxicity against a variety of cancer cells. Here we report the effects of this compound in vitro and in vivo on human prostate cancer cells, LNCaP (androgen-dependent) and PC3 (androgen-independent), in comparison with three structurally related ginsenosides, ginsenoside Rh2, ginsenoside Rg3, and 20(S)-protopanaxadiol. Of the four test compounds, 25-OCH3-PPD was most potent. It decreased survival, inhibited proliferation, induced apoptosis, and led to G1 cell cycle arrest in both cell lines. It also decreased the levels of proteins associated with cell proliferation (MDM2, E2F1, cyclin D1, and cdks 2 and 4) and increased or activated pro-apoptotic proteins (cleaved PARP, cleaved caspase-3, -8, and -9). In LNCaP cells, 25-OCH3-PPD inhibited the expression of the androgen receptor and prostate-specific antigen. Moreover, 25-OCH3-PPD inhibited the growth of prostate cancer xenograft tumours. Combining 25-OCH3-PPD with conventional chemotherapeutic agents or with radiation led to potent antitumour effects; tumour regression was almost complete following administration of 25-OCH3-PPD and either taxotere or gemcitabine. 25-OCH3-PPD also demonstrated low toxicity to noncancer cells and no observable toxicity in animals. In conclusion, our preclinical data indicate that 25-OCH3-PPD is a potential therapeutic agent against both androgen-dependent and androgen-independent prostate cancer

The prevalence of hyperuricemia in China: a meta-analysis

<p>Abstract</p> <p>Background</p> <p>The prevalence of hyperuricemia varied in different populations and it appeared to be increasing in the past decades. Recent studies suggest that hyperuricemia is an independent risk factor for cardiovascular disease. However, there has not yet been a systematic analysis of the prevalence of hyperuricemia in China.</p> <p>Methods</p> <p>Epidemiological investigations on hyperuricemia in China published in journals were identified manually and on-line by using CBMDISC, Chongqing VIP database and CNKI database. Those Reported in English journals were identified using MEDLINE database. Selected studies had to describe an original study defined by strict screening and diagnostic criteria. The fixed effects model or random effects model was employed according to statistical test for homogeneity.</p> <p>Results</p> <p>Fifty-nine studies were selected, the statistical information of which was collected for systematic analysis. The results showed that the pooled prevalence of hyperuricemia in male was 21.6% (95%CI: 18.9%-24.6%), but it was only 8.6% (95%CI: 8.2%-10.2%) in female. It was found that thirty years was the risk point age in male and it was fifty years in female.</p> <p>Conclusions</p> <p>The prevalence of hyperuricemia is different as the period of age and it increases after 30 years in male and 50 in female. Interventions are necessary to change the risk factors before the key age which is 30 years in male and 50 in female.</p

Pan-cancer analysis of whole genomes

Cancer is driven by genetic change, and the advent of massively parallel sequencing has enabled systematic documentation of this variation at the whole-genome scale(1-3). Here we report the integrative analysis of 2,658 whole-cancer genomes and their matching normal tissues across 38 tumour types from the Pan-Cancer Analysis of Whole Genomes (PCAWG) Consortium of the International Cancer Genome Consortium (ICGC) and The Cancer Genome Atlas (TCGA). We describe the generation of the PCAWG resource, facilitated by international data sharing using compute clouds. On average, cancer genomes contained 4-5 driver mutations when combining coding and non-coding genomic elements; however, in around 5% of cases no drivers were identified, suggesting that cancer driver discovery is not yet complete. Chromothripsis, in which many clustered structural variants arise in a single catastrophic event, is frequently an early event in tumour evolution; in acral melanoma, for example, these events precede most somatic point mutations and affect several cancer-associated genes simultaneously. Cancers with abnormal telomere maintenance often originate from tissues with low replicative activity and show several mechanisms of preventing telomere attrition to critical levels. Common and rare germline variants affect patterns of somatic mutation, including point mutations, structural variants and somatic retrotransposition. A collection of papers from the PCAWG Consortium describes non-coding mutations that drive cancer beyond those in the TERT promoter(4); identifies new signatures of mutational processes that cause base substitutions, small insertions and deletions and structural variation(5,6); analyses timings and patterns of tumour evolution(7); describes the diverse transcriptional consequences of somatic mutation on splicing, expression levels, fusion genes and promoter activity(8,9); and evaluates a range of more-specialized features of cancer genomes(8,10-18).Peer reviewe

Conducting polymer nanocomposite-based supercapacitors

The use of nanocomposites of electronically-conducting polymers for supercapacitors has increased significantly over the past years, due to their high capacitances and abilities to withstand many charge-discharge cycles. We have recently been investigating the use of nanocomposites of electronically-conducting polymers containing conducting and non-conducting nanomaterials such as carbon nanotubes and cellulose nanocrystals, for use in supercapacitors. In this contribution, we provide a summary of some of the key issues in this area of research. This discussion includes some history, fundamental concepts, the physical and chemical processes involved, and the challenges that these nanocomposite materials must overcome in order to become technologically viable. Due to space limitations, this is not a complete review of all the work that has been done in this field and we have focused on common themes that appear in the published work. Our aim is that this chapter will help readers to understand the advantages and challenges involved in the use of these materials in supercapacitors and to identify areas for further development

Hybrid luminescence materials assembled by [Ln(DPA) 3 ]3- and mesoporous host through ion-pairing interactions with high quantum efficiencies and long lifetimes

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Switching between symmetric and asymmetric separation-induced shock reflections in an oscillatory duct flow

Separation-induced shock reflections in straight ducts are generally considered asymmetric for Mach numbers beyond 2.2, but our experiment shows that this is not always the case. A symmetric shock pattern, a proven outcome of following the free-interaction theory (FIT), is observed to appear in an oscillatory duct flow at a Mach number of 2.47. Interestingly, its existence is restricted to the period when the shocks move forward. Once a full retreat starts, it changes suddenly into an utterly asymmetric style that conforms to the past observation. This behavior indicates that the FIT fundamentally plays a limited role in supersonic duct flows. Published under an exclusive license by AIP Publishing.</p

Flow structure of pressure transmission tube and its influence on unsteady pressure measuring results in compressible flow

The computational fluid dynamics method is introduced to study the dynamic response of pressure transmission tubes in compressible flow. A simple theoretical model based on the flow structure was developed to reveal the physical mechanism of the tube dynamic response. According to the dominant variables in the model, the influence of Mach number, tube configuration and tube cooling was numerically studied with CFD tools. The CFD results indicate that the dynamic response characteristics of a given tube in compressible flow are significantly different from that in incompressible flow, which is important to the improvement of measurement accuracy in supersonic aerodynamic experiments. The tube effect in compressible flow includes the tap-flow interaction at the entrance of the tube and the signal damping inside the tube, and the latter is less important. The tap-flow interaction makes the pressure at the pressure tap different from the true wall pressure, and as a result the traditional models are inappropriate in compressible flow. The constraint of mass flow rate caused by the tapflow interaction contributes mainly to the pressure signal distortion in compressible flow, which was not considered in existing incompressible flow studies. The measuring pressure amplitude mainly depends on the mass flow rate through the pressure sensing hole and the stagnation enthalpy change of the inflow gas in the charge process. The influence of tube configuration is negligible for incompressible flow and low-frequency input signal, but significant for compressible flow and high-frequency signal. Generally, the measuring pressure amplitude of straight tubes is closer to the true value than that of mixed diameter tubes. It is discovered that the cooled tube wall causes more serious pressure signal damping than the adiabatic tube wall. Tube cooling can reduce the amplitude ratio by 0.1 in high enthalpy flow. In addition, a method of rapid estimation of amplitude ratios is developed based on the CFD database. (C) 2020 Elsevier Masson SAS. All rights reserved.</p