Design and performance of photo-electrochemical reactors with Fe2O3 photo-anodes for water splitting

Sources of clean and sustainable energy are important vectors for economic growth and development. The current global energy supply depends heavily on fossil fuels, which in the future may have added costs of carbon dioxide emissions. This makes technology such as direct water splitting from harvesting solar energy in photo-electrochemical (PEC) systems potentially attractive. The principle of this technology utilises semiconductors to absorb photons of energy greater than their band gap energy, generating an electron-hole (absence of electron) pair. The hole could oxidise water to produce oxygen at the anode, while the electrons could reduce water to form hydrogen at the cathode. This project aims to design, model, characterise the performance and optimise a photo-electrochemical reactor that could efficiently harvest and store solar energy by splitting water to produce hydrogen and oxygen. α-Fe2O3 ,which is a cheap and abundant material, has shown promise as a photo-anode material, so was chosen as the photo-anode in the development of the PEC reactor. α-Fe2O3 thin films were produced by spray pyrolysis of alcoholic FeIII solutions onto fluorine-doped tin oxide film on glass. Effects of deposition precursor, post deposition heat treatment and SnIV-doping were studied. Results showed that both SnIV-doping and heat treatment were required to produce the best results (photocurrent of ca. 1-2 Am-2 at applied potential of 0.5 V vs. HgO |Hg). A charge carrier transport model was developed to understand and predict the behaviour of the Fe2O3. The model suggested that the magnitude of photocurrent was dependent on the photo-electrochemical reaction rate at the electrolyte | electrode interface, and would be limited by the intensity of illuminated photon flux. Operating the reactor at higher temperatures favoured the electrolysis process in the absence of light, but experimental results showed it was unfavourable for the net photo-generation of charge. A reactor system with a 0.1 m x 0.1 m photo-anode, Ti/Pt cathode and cation-permeable membrane was built to investigate the effects of operating parameters and operational issues of process scale up. COMSOL Multiphysics™ software was used to model the reactor and to study the reactor performance effects of fluid flow, light intensity and electrical potential drop in the thin conducting layer on glass. Results showed that at electrode area of 10-2 m2 scale, a significant electrical potential drop occurred across the photo-anode, due to its sheet resistance, resulting in non-uniform distribution of current density / rate of H2 (and O2) production (solar to hydrogen conversion efficiency of 0.16%), much of the photo-anode area being inactive. A reactor model was developed to provide a better understanding of larger-scale PEC reactor performance and was used to re-design and optimise the next reactor prototype

2021 Asian Pacific Society of Cardiology Consensus Recommendations on the Use of P2Y12 Receptor Antagonists in the Asia-Pacific Region: Special Populations

Advanced age, diabetes, and chronic kidney disease not only increase the risk for ischaemic events in chronic coronary syndromes (CCS) but also confer a high bleeding risk during antiplatelet therapy. These special populations may warrant modification of therapy, especially among Asians, who have displayed characteristics that are clinically distinct from Western patients. Previous guidance has been provided regarding the classification of high-risk CCS and the use of newer-generation P2Y12 inhibitors (i.e. ticagrelor and prasugrel) after acute coronary syndromes (ACS) in Asia. The authors summarise evidence on the use of these P2Y12 inhibitors during the transition from ACS to CCS and among special populations. Specifically, they present recommendations on the roles of standard dual antiplatelet therapy, shortened dual antiplatelet therapy and single antiplatelet therapy among patients with coronary artery disease, who are either transitioning from ACS to CCS; elderly; or with chronic kidney disease, diabetes, multivessel coronary artery disease and bleeding events during therapy

Extensive Promoter-Centered Chromatin Interactions Provide a Topological Basis for Transcription Regulation

Higher-order chromosomal organization for transcription regulation is poorly understood in eukaryotes. Using genome-wide Chromatin Interaction Analysis with Paired-End-Tag sequencing (ChIAPET), we mapped long-range chromatin interactions associated with RNA polymerase II in human cells and uncovered widespread promoter-centered intragenic, extragenic, and intergenic interactions. These interactions further aggregated into higher-order clusters, wherein proximal and distal genes were engaged through promoter-promoter interactions. Most genes with promoter-promoter interactions were active and transcribed cooperatively, and some interacting promoters could influence each other implying combinatorial complexity of transcriptional controls. Comparative analyses of different cell lines showed that cell-specific chromatin interactions could provide structural frameworks for cell-specific transcription, and suggested significant enrichment of enhancer-promoter interactions for cell-specific functions. Furthermore, genetically-identified disease-associated noncoding elements were found to be spatially engaged with corresponding genes through long-range interactions. Overall, our study provides insights into transcription regulation by three-dimensional chromatin interactions for both housekeeping and cell-specific genes in human cells

Robust estimation of bacterial cell count from optical density

Optical density (OD) is widely used to estimate the density of cells in liquid culture, but cannot be compared between instruments without a standardized calibration protocol and is challenging to relate to actual cell count. We address this with an interlaboratory study comparing three simple, low-cost, and highly accessible OD calibration protocols across 244 laboratories, applied to eight strains of constitutive GFP-expressing E. coli. Based on our results, we recommend calibrating OD to estimated cell count using serial dilution of silica microspheres, which produces highly precise calibration (95.5% of residuals <1.2-fold), is easily assessed for quality control, also assesses instrument effective linear range, and can be combined with fluorescence calibration to obtain units of Molecules of Equivalent Fluorescein (MEFL) per cell, allowing direct comparison and data fusion with flow cytometry measurements: in our study, fluorescence per cell measurements showed only a 1.07-fold mean difference between plate reader and flow cytometry data

Dynamic changes in the human methylome during differentiation

DNA methylation is a critical epigenetic regulator in mammalian development. Here, we present a whole-genome comparative view of DNA methylation using bisulfite sequencing of three cultured cell types representing progressive stages of differentiation: human embryonic stem cells (hESCs), a fibroblastic differentiated derivative of the hESCs, and neonatal fibroblasts. As a reference, we compared our maps with a methylome map of a fully differentiated adult cell type, mature peripheral blood mononuclear cells (monocytes). We observed many notable common and cell-type-specific features among all cell types. Promoter hypomethylation (both CG and CA) and higher levels of gene body methylation were positively correlated with transcription in all cell types. Exons were more highly methylated than introns, and sharp transitions of methylation occurred at exon–intron boundaries, suggesting a role for differential methylation in transcript splicing. Developmental stage was reflected in both the level of global methylation and extent of non-CpG methylation, with hESC highest, fibroblasts intermediate, and monocytes lowest. Differentiation-associated differential methylation profiles were observed for developmentally regulated genes, including the HOX clusters, other homeobox transcription factors, and pluripotence-associated genes such as POU5F1, TCF3, and KLF4. Our results highlight the value of high-resolution methylation maps, in conjunction with other systems-level analyses, for investigation of previously undetectable developmental regulatory mechanisms

A genome wide study of copy number variation associated with nasopharyngeal carcinoma in Malaysian Chinese identifies CNVs at 11q14.3 and 6p21.3 as candidate loci

Background: Nasopharyngeal carcinoma (NPC) is a neoplasm of the epithelial lining of the nasopharynx. Despite various reports linking genomic variants to NPC predisposition, very few reports were done on copy number variations (CNV). CNV is an inherent structural variation that has been found to be involved in cancer predisposition. Methods: A discovery cohort of Malaysian Chinese descent (NPC patients, n = 140; Healthy controls, n = 256) were genotyped using Illumina® HumanOmniExpress BeadChip. PennCNV and cnvPartition calling algorithms were applied for CNV calling. Taqman CNV assays and digital PCR were used to validate CNV calls and replicate candidate copy number variant region (CNVR) associations in a follow-up Malaysian Chinese (NPC cases, n = 465; and Healthy controls, n = 677) and Malay cohort (NPC cases, n = 114; Healthy controls, n = 124). Results: Six putative CNVRs overlapping GRM5, MICA/HCP5/HCG26, LILRB3/LILRA6, DPY19L2, RNase3/RNase2 and GOLPH3 genes were jointly identified by PennCNV and cnvPartition. CNVs overlapping GRM5 and MICA/HCP5/HCG26 were subjected to further validation by Taqman CNV assays and digital PCR. Combined analysis in Malaysian Chinese cohort revealed a strong association at CNVR on chromosome 11q14.3 (Pcombined = 1.54x10-5; odds ratio (OR) = 7.27; 95% CI = 2.96–17.88) overlapping GRM5 and a suggestive association at CNVR on chromosome 6p21.3 (Pcombined = 1.29x10-3; OR = 4.21; 95% CI = 1.75–10.11) overlapping MICA/HCP5/HCG26 genes. Conclusion: Our results demonstrated the association of CNVs towards NPC susceptibility, implicating a possible role of CNVs in NPC development

Whole-genome reconstruction and mutational signatures in gastric cancer.

BACKGROUND: Gastric cancer is the second highest cause of global cancer mortality. To explore the complete repertoire of somatic alterations in gastric cancer, we combined massively parallel short read and DNA paired-end tag sequencing to present the first whole-genome analysis of two gastric adenocarcinomas, one with chromosomal instability and the other with microsatellite instability. RESULTS: Integrative analysis and de novo assemblies revealed the architecture of a wild-type KRAS amplification, a common driver event in gastric cancer. We discovered three distinct mutational signatures in gastric cancer--against a genome-wide backdrop of oxidative and microsatellite instability-related mutational signatures, we identified the first exome-specific mutational signature. Further characterization of the impact of these signatures by combining sequencing data from 40 complete gastric cancer exomes and targeted screening of an additional 94 independent gastric tumors uncovered ACVR2A, RPL22 and LMAN1 as recurrently mutated genes in microsatellite instability-positive gastric cancer and PAPPA as a recurrently mutated gene in TP53 wild-type gastric cancer. CONCLUSIONS: These results highlight how whole-genome cancer sequencing can uncover information relevant to tissue-specific carcinogenesis that would otherwise be missed from exome-sequencing data

Schematic representation of the genomic organization according to the human genome hg18 at chromosome 11q14.3 with the positions of CNVs called in the region and reported CNVs in the vicinity found in the Database of Genomic Variants, accessed by July 2015.

<p>Blue bars represent gains identified by other studies that were deposited in the database while red bars represent losses. Brown bars depict CNVs with both losses and gains documented.</p