187 research outputs found

    Electronic Structure of V2O5 Polymorphs and MxV2O5 Bronzes

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    The energy landscape of vanadium oxide (Vv2Ov5) showcases a rich abundance of energetically proximate minima representing different metastable phases. In addition to the multiple polymorphs of Vv2Ov5, the open-framework structures can accommodate varying concentrations of metal ions within their structure to form mixed-metal oxide bronzes with the formula MvxVv2Ov5. The bonding motif of each polymorph is determined by the connectivity of V—O bonds as well as the different inserted metal ions (M) and their stoichiometry (x); these materials thus serve as an excellent sandbox for elucidating structure—function correlations. The crystal structures of these semiconductors affect the electronic structure. Both the atomistic structure as well as the electronic structure determine the utility of these materials in applications such as energy storage and switchable devices. An electronic structure property of utmost importance to functional applications is the band gap. The study here uses diffuse reflectance spectroscopy paired with Kubelka-Munk analysis to determine the band gaps of well-characterized powders of these materials. The discovery of new cathode materials that can intercalate cations and allow for both ionic and electronic transport is an urgent imperative for electrochemical energy storage. Materials with smaller band gaps tend to be better potential candidates than those with large band gaps owing to their better electronic conductivities and better ability to diffuse polarons. The band gaps of each polymorph of Vv2Ov5 are compared to evaluate the extent of covalent hybridization. The deduced band gaps of polymorphs of Vv2Ov5 are furthermore of importance for energy harvesting. By synthesizing heterostructures of Vv2Ov5 and II-VI quantum dots, type-II charge-separated interfaces can be constructed and the separated carriers can be utilized for photocatalytic reactions. The charge separation depends sensitively on the energetic offsets between the two semiconductors. In addition, the mixed metal-oxide bronzes studied here exhibit metal-insulator transitions dependent on the concentration of metal-ions present. Trends in band gap values with the changes in metal cation content shows the strong correlation of structure and application

    Optical and near-IR spectroscopy of candidate red galaxies in two z~2.5 proto-clusters

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    We present a spectroscopic campaign to follow-up red colour-selected candidate massive galaxies in two high redshift proto-clusters surrounding radio galaxies. We observed a total of 57 galaxies in the field of MRC0943-242 (z=2.93) and 33 in the field of PKS1138-262 (z=2.16) with a mix of optical and near-infrared multi-object spectroscopy. We confirm two red galaxies in the field of PKS1138-262 at the redshift of the radio galaxy. Based on an analysis of their spectral energy distributions, and their derived star formation rates from the H-alpha and 24um flux, one object belongs to the class of dust-obscured star-forming red galaxies, while the other is evolved with little ongoing star formation. This result represents the first red and mainly passively evolving galaxy to be confirmed as companion galaxies in a z>2 proto-cluster. Both red galaxies in PKS1138-262 are massive, of the order of 4-6x10^11 M_Sol. They lie along a Colour-Magnitude relation which implies that they formed the bulk of their stellar population around z=4. In the MRC0943-242 field we find no red galaxies at the redshift of the radio galaxy but we do confirm the effectiveness of our JHK_s selection of galaxies at 2.3<z<3.1, finding that 10 out of 18 (56%) of JHK_s-selected galaxies whose redshifts could be measured fall within this redshift range. We also serendipitously identify an interesting foreground structure of 6 galaxies at z=2.6 in the field of MRC0943-242. This may be a proto-cluster itself, but complicates any interpretation of the red sequence build-up in MRC0943-242 until more redshifts can be measured.Comment: 17 pages, 14 figures, accepted for publication in Astronomy and Astrophysic

    Tears in your beer: Gender differences in coping drinking motives, depressive symptoms and drinking

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    This study evaluates associations between coping drinking motives (CDM; drinking to regulate negative affect), depressive symptoms, and drinking behavior and extends the literature by also taking into account gender differences. Two hundred forty-three college students (Mean age = 22.93, SD = 6.29, 82% female) participated. Based on previous research, we expected that CDM would be positively associated with drinking and problems, particularly among those higher in depressive symptoms, as individuals experiencing higher levels of negative affect (i.e. depressive symptoms) and who drink to cope are likely to drink more and experience more alcohol-related problems. Lastly, based on established gender differences, we expected that CDM would be positively associated with drinking and problems, especially among females higher in depressive symptoms. Unexpectedly, findings suggested that CDMs were positively related to peak drinking, especially among those lower in depressive symptoms. Results further revealed a significant three-way interaction between CDM, depressive symptoms, and gender when predicting alcohol-related problems and drinking frequency. Specifically, we found that CDM were more strongly associated with problems among women who were lower in depressive symptoms; whereas CDM were more strongly associated with problems among men who were higher in depressive symptoms. These findings offer a more comprehensive depiction of the relationship between depressive symptoms, CDM, and drinking behavior by taking into account the importance of gender differences. These results provide additional support for considering gender when designing and implementing alcohol intervention strategies

    Improving the quality of set yoghurt using milk fat globule membrane fragments

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    Lacprodan PL20, a dairy ingredient that is rich in protein and polar lipids, was added into set yoghurts produced from nonhomogenized raw milk. The set yoghurts were prepared using concentrations of 2%, 4%, and 6% Lacprodan PL20, while the control sample was only supplemented with skim milk powder. The effect of Lacprodan PL20 concentrations on the physical and chemical properties, rheology, and microstructure of set yoghurt was thoroughly investigated to determine some likely improvement or changes in quality. Consequently, Lacprodan PL20 showed a gradual improvement in the set yoghurt nutritive values, water holding capacity, and apparent viscosity. The results indicated that the firmness of set yoghurt was altered which steadily improved the gel strength, especially at 4% and 6% concentrations. The fermentation process was slightly delayed at 4% and 6% concentrations and pH values were raised as Lacprodan PL20 concentration increased. The microstructures of the set yoghurts produced with Lacprodan PL20, as examined by scanning electron microscopy, revealed compacted structures with fewer and smaller holes in the gel matrices. Also, a slight color change was observed in set yoghurt using a colorimeter. These results vividly showed that Lacprodan PL20, an enriched milk fat globule membrane fragment, has the potential to improve set yoghurt quality by reducing some defects associated with set yoghurt, such as low gel strength, low dry solids, and the likes

    Family planning practices of women working in the Cambodian garment industry: a qualitative study.

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    BACKGROUND: Women working in Cambodian garment factories have unmet needs for family planning (contraception and safe abortion) services, because of their background and living conditions. This study describes their experiences regarding abortion and contraception as part of a larger project to develop an intervention to support comprehensive post-abortion care. METHODS: We conducted semi-structured interviews with women seeking abortion services at private health facilities. In addition, we interviewed the private providers of abortion and contraception services surrounding garment factories. Interviews lasted up to 60 min and were conducted in Khmer and later translated into English. A thematic analysis was undertaken, with medical abortion experiences coded according to the Cambodia comprehensive abortion care protocol. RESULTS: We interviewed 16 women and 13 providers between August and November 2018. Most women reported being married and had at least one child. Among factory workers the major reported reasons for abortion were birth spacing and financial constraints. Family, friends, or co-workers were the major information resources regarding abortion and contraception, and their positive or negative experiences strongly influenced women's attitude towards both. Medical abortion pills were not always provided with adequate instructions. Half of the participants had a manual vacuum aspiration procedure performed after medical abortion. While women knew the side effects of medical abortion, many did not know the adverse warning signs and the signs of abortion completion. Only three women started post abortion family planning, as most of the women expressed fear and hesitation due to concerns about side effects of modern contraception. Fear of infertility was particularly reported among young women without children. CONCLUSION: This research shows that in this setting not all women are receiving comprehensive abortion care and contraceptive counselling. Provision of accurate and adequate information about abortion methods and modern contraception was the dominant shortfall in abortion care. Future work to address this gap could involve the development of appropriate interventions and informative tools for women in the Cambodian garment industry such as through existing client contact-centres or social media, including creation of videos or posts on topics that come from clients questions

    Chemostat culture systems support diverse bacteriophage communities from human feces

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    BACKGROUND: Most human microbiota studies focus on bacteria inhabiting body surfaces, but these surfaces also are home to large populations of viruses. Many are bacteriophages, and their role in driving bacterial diversity is difficult to decipher without the use of in vitro ecosystems that can reproduce human microbial communities. RESULTS: We used chemostat culture systems known to harbor diverse fecal bacteria to decipher whether these cultures also are home to phage communities. We found that there are vast viral communities inhabiting these ecosystems, with estimated concentrations similar to those found in human feces. The viral communities are composed entirely of bacteriophages and likely contain both temperate and lytic phages based on their similarities to other known phages. We examined the cultured phage communities at five separate time points over 24 days and found that they were highly individual-specific, suggesting that much of the subject-specificity found in human viromes also is captured by this culture-based system. A high proportion of the community membership is conserved over time, but the cultured communities maintain more similarity with other intra-subject cultures than they do to human feces. In four of the five subjects, estimated viral diversity between fecal and cultured communities was highly similar. CONCLUSIONS: Because the diversity of phages in these cultured fecal communities have similarities to those found in humans, we believe these communities can serve as valuable ecosystems to help uncover the role of phages in human microbial communities

    Area deprivation and age related macular degeneration in the EPIC-Norfolk Eye Study.

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    OBJECTIVES: To investigate the relationship between area deprivation, individual socio-economic status (SES) and age related macular degeneration (AMD). STUDY DESIGN: Cross sectional study nested within a longitudinal cohort study. METHODS: Data were collected in the EPIC-Norfolk Eye Study by trained nurses, using standardized protocols and lifestyle questionnaires. The English Index of multiple deprivation 2010 (IMD) was derived from participants' postcodes. AMD was identified from standardized grading of fundus photographs. Logistic regression was used to examine associations between IMD, SES and AMD. RESULTS: 5344 pairs (62.0% of total 8623) of fundus photographs were of sufficient quality for grading of AMD. Of 5182 participants with complete data, AMD was identified in 653 participants (12.60%, 95%CI = 11.7-13.5%). Multivariable logistic regression showed that people living in the most affluent 5% of areas had nearly half the odds of AMD compared to those living in comparatively more deprived areas (OR = 0.56, 95% CI = 0.36-0.89, P = 0.02), after adjusting for age, sex, education, social class and smoking. CONCLUSIONS: The authors found that living in the most affluent areas exerted a protective effect on AMD, independently of education and social class. Further investigation into underlying mechanisms will inform potential interventions to reduce health inequalities relating to AMD.EPIC-Norfolk infrastructure and core functions are supported by grants from the Medical Research Council (G0401527) and Cancer Research UK (C864/A8257). The clinic for the third health examination was funded by Age UK Research into Ageing grant (262). Dr Yip is a National Institute for Health Research (NIHR) Clinical Lecturer. Dr Khawaja is a Wellcome Trust Clinical Research Fellow. Michelle Chan is an MRC/RCOphth Clinical Training Felllow and has received additional support from the International Glaucoma Association. Professor Foster has received additional support from the Richard Desmond Charitable Trust (via Fight for Sight). Professor Foster and Tunde Peto received funding from the Department for Health through the award made by the NIHR to Moorfields Eye Hospital and the UCL Institute of Ophthalmology for a specialist Biomedical Research Centre for Ophthalmology. None of the funding organisations had a role in the design or conduct of the research.This is the final version. It was first published by Elsevier at http://www.publichealthjrnl.com/article/S0033-3506%2814%2900274-1/abstrac

    Cross Sectional and Longitudinal Associations between Cardiovascular Risk Factors and Age Related Macular Degeneration in the EPIC-Norfolk Eye Study.

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    PURPOSE: To examine the cross sectional and longitudinal relationship between cardiovascular risk factors and age-related macular degeneration (AMD) in a large British cohort study. METHODS: The EPIC Norfolk Eye study is nested in a larger prospective cohort study. Data on cardiovascular risk factors were collected at baseline (1993-1997) and follow up (2006-2011) via clinical examination, validated lifestyle questionnaires and serum blood samples. AMD was ascertained using standardised grading of fundus photographs at the follow up. Logistic regression was used to examine associations between baseline and follow up risk factors with AMD. RESULTS: 5,344 pairs (62.0% of total 8623) of fundus photographs were of sufficient quality for grading of AMD in participants with mean age of 67.4 years old (range 44-91) at diagnosis. There were 28 cases of late AMD (0.5%, 95% confidence interval (CI)=0.3-0.8%) and 645 cases of early AMD (12.1%, 95%CI=11.2-13.0.%). In multivariable analysis, older people with higher levels of baseline high density lipoprotein- cholesterol (HDL-C ) and C-reactive protein (CRP) were more likely to have any signs of AMD, after adjusting for sex, education, smoking, and systolic blood pressure. In cross sectional analysis, only older age and higher HDL were significantly associated with AMD. CONCLUSIONS: We have found that older age and higher levels of CRP and HDL-C were associated with increased odds of AMD in this population in the longitudinal analysis, but older age and HDL-C, not CRP was significantly associated with AMD in the cross sectional analysis. The prevalence of AMD in this cohort was low compared to other cohorts in Europe, the US and Australia, and probably reflects the some selection biases in follow up participation as well as the low rate of smoking among our healthy participants.EPIC-Norfolk infrastructure and core functions are supported by grants from the Medical Research Council (G0401527) and Cancer Research UK (C864/A8257). The clinic for the third health examination was funded by Age UK Research into Ageing grant (262). Dr Yip is a National Institute for Health Research (NIHR) Clinical Lecturer. Dr Khawaja is a Wellcome Trust Clinical Research Fellow. Michelle Chan is an MRC/RCOphth Clinical Training Fellow and has received additional support from the International Glaucoma Association. Professor Foster has received additional support from the Richard Desmond Charitable Trust (via Fight for Sight). Professor Foster and Tunde Peto received funding from the Department for Health through the award made by the NIHR to Moorfields Eye Hospital and the UCL Institute of Ophthalmology for a specialist Biomedical Research Centre for Ophthalmology.This is the final version of the article. It first appeared from PLoS via http://dx.doi.org/10.1371/journal.pone.013256

    Parent–child cultural orientations and child adjustment in Chinese American immigrant families.

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    Direct and indirect/mediated relations of (a) children's and parents' cultural orientations and (b) parent-child gaps in cultural orientations to children's psychological adjustment were examined in a socioeconomically diverse sample of 258 Chinese American children (age = 6-9 years) from immigrant families. Parents reported on children's and their own Chinese and American orientations in language proficiency, media use, and social relationships. Parents and teachers rated children's externalizing and internalizing problems and social competence. Using structural equation modeling, we found evidence for both the effects of children's and parents' cultural orientations and the effects of parent-child gaps. Specifically, children's American orientations across domains were associated with their better adjustment (especially social competence). These associations were partly mediated by authoritative parenting. Parents' English and Chinese media use were both associated with higher authoritative parenting, which in turn was associated with children's better adjustment. Furthermore, greater gaps in parent-child Chinese proficiency were associated with children's poorer adjustment, and these relations were partly mediated by authoritative parenting. Together, the findings underscore the complex relations between immigrant families' dual orientations to the host and heritage cultures and children's psychological adjustment
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