Developing Asbestos Job Exposure Matrix Using Occupation and Industry Specific Exposure Data (1984–2008) in Republic of Korea

Background: The goal of this study is to develop a general population job-exposure matrix (GPJEM) on asbestos to estimate occupational asbestos exposure levels in the Republic of Korea. Methods: Three Korean domestic quantitative exposure datasets collected from 1984 to 2008 were used to build the GPJEM. Exposure groups in collected data were reclassified based on the current Korean Standard Industrial Classification (9th edition) and the Korean Standard Classification of Occupations code (6th edition) that is in accordance to international standards. All of the exposure levels were expressed by weighted arithmetic mean (WAM) and minimum and maximum concentrations. Results: Based on the established GPJEM, the 112 exposure groups could be reclassified into 86 industries and 74 occupations. In the 1980s, the highest exposure levels were estimated in “knitting and weaving machine operators” with a WAM concentration of 7.48 fibers/mL (f/mL); in the 1990s, “plastic products production machine operators” with 5.12 f/mL, and in the 2000s “detergents production machine operators” handling talc containing asbestos with 2.45 f/mL. Of the 112 exposure groups, 44 groups had higher WAM concentrations than the Korean occupational exposure limit of 0.1 f/mL. Conclusion: The newly constructed GPJEM which is generated from actual domestic quantitative exposure data could be useful in evaluating historical exposure levels to asbestos and could contribute to improved prediction of asbestos-related diseases among Koreans

Heterostrain-enabled dynamically tunable moiré superlattice in twisted bilayer graphene

The ability to precisely control moiré patterns in two-dimensional materials has enabled the realization of unprecedented physical phenomena including Mott insulators, unconventional superconductivity, and quantum emission. Along with the twist angle, the application of independent strain in each layer of stacked two-dimensional materials-termed heterostrain-has become a powerful means to manipulate the moiré potential landscapes. Recent experimental studies have demonstrated the possibility of continuously tuning the twist angle and the resulting physical properties. However, the dynamic control of heterostrain that allows the on-demand manipulation of moiré superlattices has yet to be experimentally realized. Here, by harnessing the weak interlayer van der Waals bonding in twisted bilayer graphene devices, we demonstrate the realization of dynamically tunable heterostrain of up to 1.3%. Polarization-resolved Raman spectroscopy confirmed the existence of substantial heterostrain by presenting triple G peaks arising from the independently strained graphene layers. Theoretical calculations revealed that the distorted moiré patterns via heterostrain can significantly alter the electronic structure of twisted bilayer graphene, allowing the emergence of multiple absorption peaks ranging from near-infrared to visible spectral ranges. Our experimental demonstration presents a new degree of freedom towards the dynamic modulation of moiré superlattices, holding the promise to unveil unprecedented physics and applications of stacked two-dimensional materials.Agency for Science, Technology and Research (A*STAR)Ministry of Education (MOE)National Research Foundation (NRF)Published versionThe research of the project was in part supported by Ministry of Education, Singapore, under grant AcRF TIER 1 2019-T1-002-050 (RG 148/19 (S)). The research of the project was also supported by Ministry of Education, Singapore, under grant AcRF TIER 2 (MOE2018-T2-2-011 (S)). This work is also supported by National Research Foundation of Singapore through the Competitive Research Program (NRF-CRP19-2017-01). This work is also supported by National Research Foundation of Singapore through the NRF-ANR Joint Grant (NRF2018-NRF-ANR009 TIGER). This work is also supported by the iGrant of Singapore A*STAR AME IRG (A2083c0053).The authors would like to acknowledge and thank the Nanyang NanoFabrication Centre (N2FC)

A Low-Power Indirect Time-of-Flight CMOS Image Sensor With Fixed Depth Noise Compensation and Dual-Mode Imaging for Depth Dynamic Range Enhancement

We present a low-power indirect time-of-flight (iTOF) image sensor with fixed depth noise compensation and dual-mode imaging for depth dynamic range (DDR) enhancement. To reduce the power consumption from high-frequency pixel modulation, a TX driver with a single-sided clock chain is employed in the sensor. The inherent phase delay of the clock chain and the delay of the row bus are measured using row-parallel and column-parallel time-to-digital converters (TDCs) to compensate for the column and row fixed depth noise (FDN). To achieve a wide depth dynamic range (WDDR), the reconfigurable pixels and column circuits support dual-mode: short-range (SR) and long-range (LR) modes. A WDDR image is generated in a single frame through the mixed reconfiguration of the pixel array and interpolation. In addition, the temporal noise is suppressed without a significant time budget through a fast multiple sampling (FMS) scheme with 10b successive approximation register (SAR) analog-to-digital (ADCs). A prototype iTOF image sensor was fabricated using a 110 nm frontside illumination (FSI) CMOS image sensor (CIS) process and fully characterized. The sensor achieved a DDR of 4 m (0.7 to 4.7 m) with less than 1.7% nonlinearity and 0.9% depth noise. The FDN was suppressed to less than 2.1 cm at a low power consumption below 70 mW through the proposed compensation scheme using row and column TDCs. The temporal noise was only 0.48 mV(rms) owing to the FMS

Influence of IL1B polymorphism on CpG island hypermethylation in Helicobacter pylori-infected gastric cancer

Helicobacter pylori infection can induce aberrant CpG island hypermethylation in gastric mucosal epithelial cells. Single nucleotide polymorphisms of proinflammatory cytokine genes encoding for interleukin 1B (IL1B), IL6, and IL8 have been demonstrated to be associated with an increased risk of gastric cancer. To identify the influence of host genetic factors in CpG island hypermethylation induced by H. pylori infection, we analyzed H. pylori-infected chronic gastritis (n = 111) and gastric cancer samples (n = 78) for the methylation status of eight genes previously shown to be hypermethylated in chronic gastritis and single nucleotide polymorphisms of IL1B, IL6, and IL8. The methylation levels were then compared between different genotypes. Gastric cancers from patients with the IL1B-511T/T allele showed significantly higher methylation levels in five genes as compared with gastric cancers from IL1B-511 C carriers (P < 0.05). An increased level of hypermethylation in association with the IL1B-511T/T allele was observed in chronic gastritis samples, but the association was not statistically significant. These findings suggest that the IL1B-511T/T allele is associated with enhanced hypermethylation of multiple CpG island loci, which might contribute to an increase in the risk for gastric cancer in individuals with H. pylori infection and IL1B-511T/T allele.Yoo EJ, 2008, VIRCHOWS ARCH, V452, P515, DOI 10.1007/s00428-008-0596-7Kang GH, 2008, LAB INVEST, V88, P161, DOI 10.1038/labinvest.3700707Perri F, 2007, AM J GASTROENTEROL, V102, P1361, DOI 10.1111/j.1572-0241.2007.01284.xChan AOO, 2007, GUT, V56, P595, DOI 10.1136/gut.2006.113258Widschwendter M, 2007, NAT GENET, V39, P157Schlesinger Y, 2007, NAT GENET, V39, P232, DOI 10.1038/ng1950Ohm JE, 2007, NAT GENET, V39, P237, DOI 10.1038/ng1972Li C, 2007, J GASTROEN HEPATOL, V22, P234, DOI 10.1111/j.1440-1746.2006.04379.xWehbe H, 2006, CANCER RES, V66, P10517, DOI 10.1158/0008-5472.CAN-06-2130Mihara M, 2006, AM J PATHOL, V169, P1643, DOI 10.2353/ajpath.2006.060552Leung WK, 2006, CLIN CANCER RES, V12, P3216, DOI 10.1158/1078-0432.CCR-05-2442Ushijima T, 2006, J GASTROENTEROL, V41, P401, DOI 10.1007/s00535-006-1846-6Ogino S, 2006, J MOL DIAGN, V8, P209, DOI 10.2353/jmoldx.2006.050135Lee TI, 2006, CELL, V125, P301Chan AOO, 2006, GUT, V55, P463, DOI 10.1136/gut.2005.077776Maekita T, 2006, CLIN CANCER RES, V12, P989, DOI 10.1158/1078-0432.CCR-05-2096Taguchi A, 2005, CANCER EPIDEM BIOMAR, V14, P2487, DOI 10.1158/1055-9965.EPI-05-0326Hodge DR, 2005, CANCER RES, V65, P4673Chang YW, 2005, INT J CANCER, V114, P465, DOI 10.1002/ijc.20724Chan AOO, 2003, GUT, V52, P502Hwang IR, 2002, GASTROENTEROLOGY, V123, P1793, DOI 10.1053/gast.2002.37043Trinh BN, 2001, METHODS, V25, P456, DOI 10.1006/meth.2001.1268Hodge DR, 2001, J BIOL CHEM, V276, P39508Terry CF, 2000, J BIOL CHEM, V275, P18138El-Omar EM, 2000, NATURE, V404, P398EADS CA, 2000, NUCLEIC ACIDS RES, V28, P32, DOI DOI 10.1093/NAR/28.8.E32Hmadcha A, 1999, J EXP MED, V190, P1595Wang MC, 1999, J GASTROENTEROL, V34, P10Jones PA, 1999, NAT GENET, V21, P163Fishman D, 1998, J CLIN INVEST, V102, P1369Olomolaiye O, 1998, EUR J IMMUNOGENET, V25, P267*IARC WORK GROUP E, 1994, IARC MON EV CARC RIS, V61, P1WALLACE JL, 1991, AM J PHYSIOL, V261, P559

Estimating Benzene Exposure Level over Time and by Industry Type through a Review of Literature on Korea

The major purpose of this study is to construct a retrospective exposure assessment for benzene through a review of literature on Korea. Airborne benzene measurements reported in 34 articles were reviewed. A total of 15,729 individual measurements were compiled. Weighted arithmetic means [AM(w)] and their variance calculated across studies were summarized according to 5-year period intervals (prior to the 1970s through the 2010s) and industry type. Industries were classified according to Korea Standard Industrial Classification (KSIC) using information provided in the literature. We estimated quantitative retrospective exposure to benzene for each cell in the matrix through a combination of time and KSIC. Analysis of the AM(w) indicated reductions in exposure levels over time, regardless of industry, with mean levels prior to the 1980–1984 period of 50.4 ppm (n = 2,289), which dropped to 2.8 ppm (n = 305) in the 1990–1994 period, and to 0.1 ppm (n = 294) in the 1995–1999 period. There has been no improvement since the 2000s, when the AM(w) of 4.3 ppm (n = 6,211) for the 2005–2009 period and 4.5 ppm (n = 3,358) for the 2010–2013 period were estimated. A comparison by industry found no consistent patterns in the measurement results. Our estimated benzene measurements can be used to determine not only the possibility of retrospective exposure to benzene, but also to estimate the level of quantitative or semiquantitative retrospective exposure to benzene

Biaxially strained germanium crossbeam with a high-quality optical cavity for on-chip laser applications

The creation of CMOS compatible light sources is an important step for the realization of electronic-photonic integrated circuits. An efficient CMOS-compatible light source is considered the final missing component towards achieving this goal. In this work, we present a novel crossbeam structure with an embedded optical cavity that allows both a relatively high and fairly uniform biaxial strain of ~0.9% in addition to a high-quality factor of >4,000 simultaneously. The induced biaxial strain in the crossbeam structure can be conveniently tuned by varying geometrical factors that can be defined by conventional lithography. Comprehensive photoluminescence measurements and analyses confirmed that optical gain can be significantly improved via the combined effect of low temperature and high strain, which is supported by a three-fold reduction of the full width at half maximum of a cavity resonance at ~1,940 nm. Our demonstration opens up the possibility of further improving the performance of germanium lasers by harnessing geometrically amplified biaxial strain.Agency for Science, Technology and Research (A*STAR)Ministry of Education (MOE)National Research Foundation (NRF)Published versio

Dataset for: Interaction of replication protein A with two acidic peptides from human Bloom syndrome protein

Bloom syndrome protein (BLM) is one of five human RecQ helicases which maintain genomic stability. Interaction of BLM with replication protein A (RPA) stimulates the DNA unwinding ability of BLM. The interaction is expected to be crucial in DNA damage response systems. Although this stimulation of BLM by RPA is of particular importance in cancer cells, the precise binding surfaces of both proteins are not well understood. In this study, we show by fluorescence polarization anisotropy that both of BLM’s acidic surface peptides specifically bind to RPA70N. Our NMR analysis and docking models show that the basic cleft region of RPA70N is the binding site for both peptides and that the acidic peptide/basic cleft interaction governs RPA-BLM binding