Energy conversion efficiency of pulsed ultrasound

Energy characterization of a pulsed ultrasonic system was carried out using a modified calorimetric method. Sonochemical efficiency (SE) for the oxidation of Fe+2 and the formation of H2O2 was determined for selected on:off ratios (R) and different power levels. The measured efficiency of the pulsed ultrasonic system of 60-70% in converting electrical energy into calorimetric energy was found to be constant for all Rratios and equivalent to that for continuous operation. SE of Fe+2 and H2O2 for pulsed ultrasound was higher than that of continuous ultrasound. The ratio R=0.2:0.1 had the highest SE values overall, while for long off-timeratios,R=0.1:0.6 recorded the highest value of SE. These results were supported by the production rates results for Fe+2 and H2O2

Investigation of ethanol production potential from lignocellulosic material without enzymatic hydrolysis using the ultrasound technique

This research investigates ethanol production from waste lignocellulosic material (sugarcane bagasse). The bagasse was first pretreated using chemicals and ultrasound techniques. These pretreatment techniques were applied separately and combined. The pretreated bagasse was then fermented anaerobically for biofuel production without enzymatic hydrolysis. The results showed higher ethanol production than those reported in the literature. The maximum ethanol production of 820 mg/L was achieved with a combination of ultrasound (60 amplitude level, 127 W) and acid (3% H2SO4 concentration). The combination of two-step pretreatment such as an ultrasound (50 amplitude level, 109 W) with acid (3% H2SO4 concentration) and then an ultrasound with alkaline (23% NaOH concentration) generated 911 mg/L of ethanol

Ovarian and Breast Cancer Risks Associated With Pathogenic Variants in RAD51C and RAD51D.

BACKGROUND: The purpose of this study was to estimate precise age-specific tubo-ovarian carcinoma (TOC) and breast cancer (BC) risks for carriers of pathogenic variants in RAD51C and RAD51D. METHODS: We analyzed data from 6178 families, 125 with pathogenic variants in RAD51C, and 6690 families, 60 with pathogenic variants in RAD51D. TOC and BC relative and cumulative risks were estimated using complex segregation analysis to model the cancer inheritance patterns in families while adjusting for the mode of ascertainment of each family. All statistical tests were two-sided. RESULTS: Pathogenic variants in both RAD51C and RAD51D were associated with TOC (RAD51C: relative risk [RR] = 7.55, 95% confidence interval [CI] = 5.60 to 10.19; P = 5 × 10-40; RAD51D: RR = 7.60, 95% CI = 5.61 to 10.30; P = 5 × 10-39) and BC (RAD51C: RR = 1.99, 95% CI = 1.39 to 2.85; P = 1.55 × 10-4; RAD51D: RR = 1.83, 95% CI = 1.24 to 2.72; P = .002). For both RAD51C and RAD51D, there was a suggestion that the TOC relative risks increased with age until around age 60 years and decreased thereafter. The estimated cumulative risks of developing TOC to age 80 years were 11% (95% CI = 6% to 21%) for RAD51C and 13% (95% CI = 7% to 23%) for RAD51D pathogenic variant carriers. The estimated cumulative risks of developing BC to 80 years were 21% (95% CI = 15% to 29%) for RAD51C and 20% (95% CI = 14% to 28%) for RAD51D pathogenic variant carriers. Both TOC and BC risks for RAD51C and RAD51D pathogenic variant carriers varied by cancer family history and could be as high as 32-36% for TOC, for carriers with two first-degree relatives diagnosed with TOC, or 44-46% for BC, for carriers with two first-degree relatives diagnosed with BC. CONCLUSIONS: These estimates will facilitate the genetic counseling of RAD51C and RAD51D pathogenic variant carriers and justify the incorporation of RAD51C and RAD51D into cancer risk prediction models

Fine-Scale Mapping of the 4q24 Locus Identifies Two Independent Loci Associated with Breast Cancer Risk

Background: A recent association study identified a common variant (rs9790517) at 4q24 to be associated with breast cancer risk. Independent association signals and potential functional variants in this locus have not been explored. Methods: We conducted a fine-mapping analysis in 55,540 breast cancer cases and 51,168 controls from the Breast Cancer Association Consortium. Results: Conditional analyses identified two independent association signals among women of European ancestry, represented by rs9790517 [conditional P = 2.51 × 10−4; OR, 1.04; 95% confidence interval (CI), 1.02–1.07] and rs77928427 (P = 1.86 × 10−4; OR, 1.04; 95% CI, 1.02–1.07). Functional annotation using data from the Encyclopedia of DNA Elements (ENCODE) project revealed two putative functional variants, rs62331150 and rs73838678 in linkage disequilibrium (LD) with rs9790517 (r2 ≥ 0.90) residing in the active promoter or enhancer, respectively, of the nearest gene, TET2. Both variants are located in DNase I hypersensitivity and transcription factor–binding sites. Using data from both The Cancer Genome Atlas (TCGA) and Molecular Taxonomy of Breast Cancer International Consortium (METABRIC), we showed that rs62331150 was associated with level of expression of TET2 in breast normal and tumor tissue. Conclusion: Our study identified two independent association signals at 4q24 in relation to breast cancer risk and suggested that observed association in this locus may be mediated through the regulation of TET2. Impact: Fine-mapping study with large sample size warranted for identification of independent loci for breast cancer risk

A case-only study to identify genetic modifiers of breast cancer risk for BRCA1/BRCA2 mutation carriers

Breast cancer (BC) risk for BRCA1 and BRCA2 mutation carriers varies by genetic and familial factors. About 50 common variants have been shown to modify BC risk for mutation carriers. All but three, were identified in general population studies. Other mutation carrier-specific susceptibility variants may exist but studies of mutation carriers have so far been underpowered. We conduct a novel case-only genome-wide association study comparing genotype frequencies between 60,212 general population BC cases and 13,007 cases with BRCA1 or BRCA2 mutations. We identify robust novel associations for 2 variants with BC for BRCA1 and 3 for BRCA2 mutation carriers, P < 10−8, at 5 loci, which are not associated with risk in the general population. They include rs60882887 at 11p11.2 where MADD, SP11 and EIF1, genes previously implicated in BC biology, are predicted as potential targets. These findings will contribute towards customising BC polygenic risk scores for BRCA1 and BRCA2 mutation carriers

A case-only study to identify genetic modifiers of breast cancer risk for BRCA1/BRCA2 mutation carriers

Abstract: Breast cancer (BC) risk for BRCA1 and BRCA2 mutation carriers varies by genetic and familial factors. About 50 common variants have been shown to modify BC risk for mutation carriers. All but three, were identified in general population studies. Other mutation carrier-specific susceptibility variants may exist but studies of mutation carriers have so far been underpowered. We conduct a novel case-only genome-wide association study comparing genotype frequencies between 60,212 general population BC cases and 13,007 cases with BRCA1 or BRCA2 mutations. We identify robust novel associations for 2 variants with BC for BRCA1 and 3 for BRCA2 mutation carriers, P < 10−8, at 5 loci, which are not associated with risk in the general population. They include rs60882887 at 11p11.2 where MADD, SP11 and EIF1, genes previously implicated in BC biology, are predicted as potential targets. These findings will contribute towards customising BC polygenic risk scores for BRCA1 and BRCA2 mutation carriers

A case-only study to identify genetic modifiers of breast cancer risk for BRCA1/BRCA2 mutation carriers

Breast cancer (BC) risk for BRCA1 and BRCA2 mutation carriers varies by genetic and familial factors. About 50 common variants have been shown to modify BC risk for mutation carriers. All but three, were identified in general population studies. Other mutation carrier-specific susceptibility variants may exist but studies of mutation carriers have so far been underpowered. We conduct a novel case-only genome-wide association study comparing genotype frequencies between 60,212 general population BC cases and 13,007 cases with BRCA1 or BRCA2 mutations. We identify robust novel associations for 2 variants with BC for BRCA1 and 3 for BRCA2 mutation carriers, P < 10−8, at 5 loci, which are not associated with risk in the general population. They include rs60882887 at 11p11.2 where MADD, SP11 and EIF1, genes previously implicated in BC biology, are predicted as potential targets. These findings will contribute towards customising BC polygenic risk scores for BRCA1 and BRCA2 mutation carriers

Retrospective evaluation of whole exome and genome mutation calls in 746 cancer samples

Funder: NCI U24CA211006Abstract: The Cancer Genome Atlas (TCGA) and International Cancer Genome Consortium (ICGC) curated consensus somatic mutation calls using whole exome sequencing (WES) and whole genome sequencing (WGS), respectively. Here, as part of the ICGC/TCGA Pan-Cancer Analysis of Whole Genomes (PCAWG) Consortium, which aggregated whole genome sequencing data from 2,658 cancers across 38 tumour types, we compare WES and WGS side-by-side from 746 TCGA samples, finding that ~80% of mutations overlap in covered exonic regions. We estimate that low variant allele fraction (VAF < 15%) and clonal heterogeneity contribute up to 68% of private WGS mutations and 71% of private WES mutations. We observe that ~30% of private WGS mutations trace to mutations identified by a single variant caller in WES consensus efforts. WGS captures both ~50% more variation in exonic regions and un-observed mutations in loci with variable GC-content. Together, our analysis highlights technological divergences between two reproducible somatic variant detection efforts

DC offset elimination in a single-phase grid-connected photovoltaic system

[Abstract]: Australian Standard AS 4777.2-2005, section 4.9 imposes limits on DC injection into the AC network by grid connected inverters. One way to ensure that this requirement is met is to use a power transformer as interface between the output of the inverter and the AC network. But this adds costs, mass, volume and power losses. It is, therefore, an advantage to design the inverter system so that zero DC offset is guaranteed at its output. Ideally no DC would be expected at the output of the inverter. In practice, however, in the absence of special measures, a small amount of DC is present because of circuit component imperfections. Techniques that have been proposed so far for the elimination of the DC offset current are based on the sensing of the DC offset voltage at the output of the inverter. The output of the sensor is used to drive a feedback system designed to control operation of the inverter so that the DC offset is eliminated. The focus of this paper is on the mathematical modeling of a recently proposed dc offset sensor and dc offset control system. Experimental validation of the model is presented. It is demonstrated that while satisfactory performance is achievable the technique has some serious disadvantages

Power quality and efficiency improvements for transformerless grid connected PV inverters

There is currently significant growth in the number of residential scale grid connected photovoltaic (PV) systems. Generally, if environmental costs are not accounted for, the cost of generation from PV sources remains high compared to conventionally generated electricity. There is, therefore, a strong incentive to reduce the cost of PV systems and improve their efficiency while satisfying injected power quality standards. The focus has been on the power electronic single phase converter bridge which is typically used as interface between the DC output of the PV panels and the terminals of the AC network. One of the two main objectives was to investigate the possibility of operating an inverter connected to the AC grid without an interfacing power transformer, while keeping DC injection into the grid below levels specified by Australian and International Standards. A low cost method of controlling the DC offset content of the current injected into the AC mains has been proposed. A mathematical model of the DC offset controller has been developed and experimentally validated. A design procedure for the controller has also been developed. The second objective was to investigate the dependence of efficiency on inverter switching strategies such as bipolar and unipolar switching. It was confirmed by specially designed tests that unipolar switching meant significantly lower switching losses when compared with bipolar switching. However, the quality of current injected into the AC mains in the case of unipolar switching was not considered acceptable because of significant current distortion near the AC mains voltage zero crossing. A new method of inverter switching has been proposed which exploits the efficiency advantage of unipolar switching while avoiding the problem of current distortion. The main outcomes of this project are a DC offset controller which allow transformerless operation and an inverter switching strategy that results in significantly reduced switching losses while maintaining the quality of injected current. Implementation of the proposed DC offset controller and inverter switching strategy will result in both capital cost savings and higher conversion efficiency