Direct observation of irradiation-induced nanocavity shrinkage in Si

Nanocavities in Si substrates, formed by conventional H implantation and thermal annealing, are shown to evolve in size during subsequent Si irradiation. Both ex situ and in situ analytical techniques were used to demonstrate that the mean nanocavity diameter decreases as a function of Si irradiation dose in both the crystalline and amorphous phases. Potential mechanisms for this irradiation-induced nanocavity evolution are discussed. In the crystalline phase, the observed decrease in diameter is attributed to the gettering of interstitials. When the matrix surrounding the cavities is amorphized, cavity shrinkage may be mediated by one of two processes: nanocavities can supply vacancies into the amorphous phase and/or the amorphous phase may flow plastically into the nanocavities. Both processes yield the necessary decrease in density of the amorphous phase relative to crystalline material

Structural effect of heavy ion irradiation on GdBaCuO ceramics

The influence of twin boundaries as sinks on defects induced by 480 keV Kr ion irradiation in GdBaCuO crystals was observed in situ at 40 and 300 K. The interaction of the dislocations with the twin boundaries followed on a video recording. A crystalline to amorphous transition was observed above a total fluence of ∼ 4 - 5 x 10^12 Kr/cm2. A comparison between orthorhombic (Os) crystals and a monoclinic structure (Ms) (close to Os and whose parameters were calculated) shows that the behaviour of irradiation-induced extended defects does not depend on a small initial deformation of the orthorhombic cell. In both case, an occasional orthorhombic (or monoclinic) to tetragonal phase transition only occurs when the amorphization process has begun

Structural and nuclear characterizations of defects created by noble gas implantation in silicon oxide

Thermally grown silicon oxide layer was implanted at room temperature with 300keV Xe at fluences ranging from 0.5 to 5x10$^16$Xe/cm$^2$. Bubbles created after Xe-implantation provided a low-k silicon oxide that has potential use as a dielectric material for interconnects in Si integrated circuits. Transmission Electron Microscopy (TEM), Rutherford Backscattering Spectrometry (RBS) and Positron Annihilation Spectroscopy (PAS) were used to provide a comprehensive characterization of defects (bubbles, vacancy, gas atoms and other types of defects) created by Xe implantation in $SiO_2$ layer. These measurements suggest that the bubbles observed with TEM for all fluences were a consequence of the interaction between Xe and vacancies (V), with $V_nXe_m$ complexes created in the zone where V and Xe profiles overlap. Negatively charged defects such as ($Si-O^-$, $Si-O-O^-$ and $O_2^-$) are also created after implantation

Preferential amorphization and defect annihilation at nanocavities in silicon during ion irradiation

Si containing a band of nanocavities has been irradiated with Si+ ions at elevated temperatures to study interactions of irradiation-induced defects with open volume defects. For irradiation at 100 degreesC, nanocavities are shown to be preferential nucleation sites for amorphization. It is proposed that this behavior occurs to minimize the local free energy, whereby less dense amorphous Si is free to expand into the cavity open volume. Furthermore, for irradiation at 300 degreesC, cavities are very efficient sinks for Si interstitials during irradiation, leaving a region denuded of interstitial-based clusters surrounding each nanocavity. (C) 2000 American Institute of Physics. [S0003-6951(00)01552-7]

Exposure to bacterial products lipopolysaccharide and flagellin and hepatocellular carcinoma: a nested case-control study.

BACKGROUND: Leakage of bacterial products across the gut barrier may play a role in liver diseases which often precede the development of liver cancer. However, human studies, particularly from prospective settings, are lacking. METHODS: We used a case-control study design nested within a large prospective cohort to assess the association between circulating levels of anti-lipopolysaccharide (LPS) and anti-flagellin immunoglobulin A (IgA) and G (IgG) (reflecting long-term exposures to LPS and flagellin, respectively) and risk of hepatocellular carcinoma. A total of 139 men and women diagnosed with hepatocellular carcinoma between 1992 and 2010 were matched to 139 control subjects. Multivariable rate ratios (RRs), including adjustment for potential confounders, hepatitis B/C positivity, and degree of liver dysfunction, were calculated with conditional logistic regression. RESULTS: Antibody response to LPS and flagellin was associated with a statistically significant increase in the risk of hepatocellular carcinoma (highest vs. lowest quartile: RR = 11.76, 95% confidence interval = 1.70-81.40; P trend = 0.021). This finding did not vary substantially by time from enrollment to diagnosis, and did not change after adjustment for chronic infection with hepatitis B and C viruses. CONCLUSIONS: These novel findings, based on exposures up to several years prior to diagnosis, support a role for gut-derived bacterial products in hepatocellular carcinoma development. Further study into the role of gut barrier failure and exposure to bacterial products in liver diseases is warranted.This work was supported by the French National Cancer Institute (L’Institut National du Cancer; INCA) (grant number 2009-139; Principal Investigator: M. Jenab). The coordination of EPIC is financially supported by the European Commission (DG-SANCO) and the International Agency for Research on Cancer. The national cohorts are supported by the Danish Cancer Society (Denmark); Ligue Contre le Cancer, Institut Gustave Roussy, Mutuelle Générale de l’Education Nationale, and Institut National de la Santé et de la Recherche Médicale (INSERM) (France); Deutsche Krebshilfe, Deutsches Krebsforschungszentrum, and Federal Ministry of Education and Research (Germany); the Hellenic Health Foundation (Greece); the Sicilian Government, AIRE ONLUS Ragusa, AVIS Ragusa, Associazione Italiana per la Ricerca sul Cancro-AIRC-Italy, and National Research Council (Italy); Dutch Ministry of Public Health, Welfare and Sports (VWS), Netherlands Cancer Registry (NKR), LK Research Funds, Dutch Prevention Funds, Dutch ZON (Zorg Onderzoek Nederland), World Cancer Research Fund (WCRF), and Statistics Netherlands (the Netherlands); Nordic Centre of Excellence programme on Food, Nutrition and Health. (Norway); Health Research Fund (FIS), PI13/00061 to Granada), Regional Governments of Andalucía, Asturias, Basque Country, Murcia (no. 6236) and Navarra, Regional Government of Asturias (Asturias, Spain), and ISCIII RETIC (RD06/0020) (Spain); Swedish Cancer Society, Swedish Scientific Council, and County Councils of Skåne and Västerbotten (Sweden); Cancer Research UK (14136 to EPIC-Norfolk; C570/A16491 to EPIC-Oxford) and Medical Research Council (1000143 to EPIC-Norfolk) (United Kingdom); and a Girdlers’ New Zealand Health Research Council Fellowship (to Dr. K.E. Bradbury). The funding sources had no influence on the design of the study; the collection, analysis, and interpretation of data; the writing of the report; or the decision to submit the paper for publication

Adult weight change and premenopausal breast cancer risk: A prospective pooled analysis of data from 628,463 women.

Early-adulthood body size is strongly inversely associated with risk of premenopausal breast cancer. It is unclear whether subsequent changes in weight affect risk. We pooled individual-level data from 17 prospective studies to investigate the association of weight change with premenopausal breast cancer risk, considering strata of initial weight, timing of weight change, other breast cancer risk factors and breast cancer subtype. Hazard ratios (HR) and 95% confidence intervals (CI) were obtained using Cox regression. Among 628,463 women, 10,886 were diagnosed with breast cancer before menopause. Models adjusted for initial weight at ages 18-24 years and other breast cancer risk factors showed that weight gain from ages 18-24 to 35-44 or to 45-54 years was inversely associated with breast cancer overall (e.g., HR per 5 kg to ages 45-54: 0.96, 95% CI: 0.95-0.98) and with oestrogen-receptor(ER)-positive breast cancer (HR per 5 kg to ages 45-54: 0.96, 95% CI: 0.94-0.98). Weight gain from ages 25-34 was inversely associated with ER-positive breast cancer only and weight gain from ages 35-44 was not associated with risk. None of these weight gains were associated with ER-negative breast cancer. Weight loss was not consistently associated with overall or ER-specific risk after adjusting for initial weight. Weight increase from early-adulthood to ages 45-54 years is associated with a reduced premenopausal breast cancer risk independently of early-adulthood weight. Biological explanations are needed to account for these two separate factors

Blood pressure and risk of cancer in the European Prospective Investigation into Cancer and Nutrition.

Several studies have reported associations of hypertension with cancer, but not all results were conclusive. We examined the association of systolic (SBP) and diastolic (DBP) blood pressure with the development of incident cancer at all anatomical sites in the European Prospective Investigation into Cancer and Nutrition (EPIC). Hazard ratios (HRs) (95% confidence intervals) were estimated using multivariable Cox proportional hazards models, stratified by EPIC-participating center and age at recruitment, and adjusted for sex, education, smoking, body mass index, physical activity, diabetes and dietary (in women also reproductive) factors. The study included 307,318 men and women, with an average follow-up of 13.7 (standard deviation 4.4) years and 39,298 incident cancers. We confirmed the expected positive association with renal cell carcinoma: HR = 1.12 (1.08-1.17) per 10 mm Hg higher SBP and HR = 1.23 (1.14-1.32) for DBP. We additionally found positive associations for esophageal squamous cell carcinoma (SCC): HR = 1.16 (1.07-1.26) (SBP), HR = 1.31 (1.13-1.51) (DBP), weaker for head and neck cancers: HR = 1.08 (1.04-1.12) (SBP), HR = 1.09 (1.01-1.17) (DBP) and, similarly, for skin SCC, colon cancer, postmenopausal breast cancer and uterine adenocarcinoma (AC), but not for esophageal AC, lung SCC, lung AC or uterine endometroid cancer. We observed weak inverse associations of SBP with cervical SCC: HR = 0.91 (0.82-1.00) and lymphomas: HR = 0.97 (0.93-1.00). There were no consistent associations with cancers in other locations. Our results are largely compatible with published studies and support weak associations of blood pressure with cancers in specific locations and morphologies

Photoperiod Influences Growth and mll (Mixed-Lineage Leukaemia) Expression in Atlantic Cod

Photoperiod is associated to phenotypic plasticity of somatic growth in several teleost species. However, the molecular mechanisms underlying this phenomenon are currently unknown but it is likely that epigenetic regulation by methyltransferases is involved. The MLL (mixed-lineage leukaemia) family comprises histone methyltransferases that play a critical role in regulating gene expression during early development in mammals. So far, these genes have received scant attention in teleost fish. In the present study, the mean weight of Atlantic cod juveniles reared under continuous illumination was found to be 13% greater than those kept under natural photoperiod conditions for 120 days. We newly determined cDNA sequences of five mll (mll1, mll2, mll3a, mll4b and mll5) and two setd1 (setd1a and setd1ba) paralogues from Atlantic cod. Phylogenetic analysis revealed that the cod genes clustered within the appropriate mll clade and comparative mapping of mll paralogues showed that these genes lie within a region of conserved synteny among teleosts. All mll and setd1 genes were highly expressed in gonads and fast muscle of adult cod, albeit at different levels, and they were differentially regulated with photoperiod in muscle of juvenile fish. Following only one day of exposure to constant light, mll1, mll4b and setd1a were up to 57% lower in these fish compared to the natural photoperiod group. In addition, mRNA expression of myogenic regulatory factors (myog and myf-5) and pax7 in fast muscle was also affected by different photoperiod conditions. Notably, myog was significantly elevated in the continuous illumination group throughout the time course of the experiment. The absence of a day/night cycle is associated with a generalised decrease in mll expression concomitant with an increase in myog transcript levels in fast muscle of Atlantic cod, which may be involved in the observed epigenetic regulation of growth by photoperiod in this species

Association between physical activity and risk of hepatobiliary cancers : A multinational cohort study

Background & Aims: To date, evidence on the association between physical activity and risk of hepatobiliary cancers has been inconclusive. Weexamined this association in the European Prospective Investigation into Cancer and Nutrition cohort (EPIC). Methods: We identified 275 hepatocellular carcinoma (HCC) cases, 93 intrahepatic bile duct cancers (IHBCs), and 164 non-gallbladder extrahepatic bile duct cancers (NGBCs) among 467,336 EPIC participants (median follow-up 14.9 years). We estimated cause-specific hazard ratios (HRs) for total physical activity and vigorous physical activity and performed mediation analysis and secondary analyses to assess robustness to confounding (e.g. due to hepatitis virus infection). Results: In the EPIC cohort, the multivariable-adjusted HR of HCC was 0.55 (95% CI 0.38-0.80) comparing active and inactive individuals. Regarding vigorous physical activity, for those reporting >2 hours/week compared to those with no vigorous activity, the HR for HCC was 0.50 (95% CI 0.33-0.76). Estimates were similar in sensitivity analyses for confounding. Total and vigorous physical activity were unrelated to IHBC and NGBC. In mediation analysis, waist circumference explained about 40% and body mass index 30% of the overall association of total physical activity and HCC. Conclusions: These findings suggest an inverse association between physical activity and risk of HCC, which is potentially mediated by obesity. Lay summary: In a pan-European study of 467,336 men and women, we found that physical activity is associated with a reduced risk of developing liver cancers over the next decade. This risk was independent of other liver cancer risk factors, and did not vary by age, gender, smoking status, body weight, and alcohol consumption. (C) 2019 European Association for the Study of the Liver. Published by Elsevier B.V. All rights reserved.Peer reviewe