Polyhedral Model of Carbon Nanotubes Analytically Describing their Geometry

For carbon nanotubes, there is constructed a geometric model of polyhedral type, which allows the expressing their key structural parameters analytically, as functions of C–C bonds length and nanotube indices. In general, explicit formulas are obtained for 1D lattice constant and radius. Cylindrical coordinates of atomic sites and inter-site distances in carbon nanotubes are additionally found for achiral (zigzag and armchair) nanotubes. „Analytic‟ geometric model will be useful for theoretical determination of groundstate and electronic structure parameters of carbon nanotubular materials, credible analysis of corresponding experimental data, as well as purposeful designing devices based on nanotubular carbon

Роль бора у формуванні вторинних радіаційних дефектів в кремнії

Influence of boron impurities on electron-transport in crystalline silicon is well known because p-Si – basic semiconducting material of the modern microelectronics – usually is obtained by doping with B. It is too important to understand the mechanism interaction of B dopants with radiation defects in silicon to (i) develop effective radiation treatment technologies for electronic devices and integrated circuits, (ii) improve their radiation resistance, and (iii) design effective solid-state radiation sensors and detectors.Based on authors’ previous works the role of B-impurities in formation of secondary radiation defects in Si crystals is investigated. Dependences of these processes on isochronous annealing temperature (80–600 °C) are studied by using the Hall measurements of temperature-dependencies (100–300 K) of holes’ concentration and mobility in silicon before and after irradiation with 8 MeV electrons at the dose of 5∙1015 cm–2. Two main conclusions are made: boron atoms in silicon crystals (i) serve as extremely active sinks of radiation defects, and (ii) participate in space-charge-screening of the relatively high-conductive inclusions in form of clusters of radiation defects.Основываясь на прежние работы авторов исследована роль примесей бора (B) в формировании вторичных радиационных дефектов в кристаллах кремния (Si). Зависимости этих процессов от температуры изохронного отжига (в интервале 80–600 °C) изучены с использованием холловских измерений температурных зависимостей (в интервале 100–300 К) концентрации и подвижности дырок в кремний до и после облучения электронами с энергией около 8 МэВ при дозе 5∙1015 см–2.Ґрунтуючись на колишні роботи авторів, досліджено роль домішок бору (B) у формуванні вторинних радіаційних дефектів в кристалах кремнію (Si). Залежності цих процесів від температури ізохронного відпалу (в інтервалі 80-600 °C) вивчені з використанням холлівських вимірювань температурних залежностей (в інтервалі 100-300 К) концентрації і рухливості дірок в кремній до і після опромінення електронами з енергією близько 8 МэВ при дозі 5∙1015 см–2

Роль бора у формуванні вторинних радіаційних дефектів в кремнії

Influence of boron impurities on electron-transport in crystalline silicon is well known because p-Si – basic semiconducting material of the modern microelectronics – usually is obtained by doping with B. It is too important to understand the mechanism interaction of B dopants with radiation defects in silicon to (i) develop effective radiation treatment technologies for electronic devices and integrated circuits, (ii) improve their radiation resistance, and (iii) design effective solid-state radiation sensors and detectors.Based on authors’ previous works the role of B-impurities in formation of secondary radiation defects in Si crystals is investigated. Dependences of these processes on isochronous annealing temperature (80–600 °C) are studied by using the Hall measurements of temperature-dependencies (100–300 K) of holes’ concentration and mobility in silicon before and after irradiation with 8 MeV electrons at the dose of 5∙1015 cm–2. Two main conclusions are made: boron atoms in silicon crystals (i) serve as extremely active sinks of radiation defects, and (ii) participate in space-charge-screening of the relatively high-conductive inclusions in form of clusters of radiation defects.Основываясь на прежние работы авторов исследована роль примесей бора (B) в формировании вторичных радиационных дефектов в кристаллах кремния (Si). Зависимости этих процессов от температуры изохронного отжига (в интервале 80–600 °C) изучены с использованием холловских измерений температурных зависимостей (в интервале 100–300 К) концентрации и подвижности дырок в кремний до и после облучения электронами с энергией около 8 МэВ при дозе 5∙1015 см–2.Ґрунтуючись на колишні роботи авторів, досліджено роль домішок бору (B) у формуванні вторинних радіаційних дефектів в кристалах кремнію (Si). Залежності цих процесів від температури ізохронного відпалу (в інтервалі 80-600 °C) вивчені з використанням холлівських вимірювань температурних залежностей (в інтервалі 100-300 К) концентрації і рухливості дірок в кремній до і після опромінення електронами з енергією близько 8 МэВ при дозі 5∙1015 см–2

Seroprevalence of Brucellosis in Livestock within Three Endemic Regions of the Country of Georgia

Brucellosis is the one of most common livestock zoonoses in Georgia, resulting in significant economic losses. Livestock were sampled in three regions of Georgia (Kakheti, Kvemo Kartli, Imereti). Districts that historically reported high numbers of brucellosis related morbidity were selected for serological, bacteriological and molecular surveys. Surveying efforts yielded samples from 10,819 large and small ruminants. In total, 735 serological tests were positive on Rose Bengal and 33 bacterial isolates were recovered and identified as Brucella melitensis or Brucella abortus by microbiology and AMOS-PCR. A Bayesian framework was implemented to estimate the true prevalence of the disease given an imperfect diagnostic test. Regional posterior median true prevalence estimates ranged from 2.7% (95% CI: 1.4, 7.2) in Kvemo Kartli, 0.8% (95% CI: 0.0, 3.6) in Kakheti, to an estimate of 0.6% (95% CI: 0.0, 2.9) in Imereti. Accurate and efficient surveillance of brucellosis is not only of economic value, but also informs efforts to reduce the disease impact on the human population

Associations between Influenza Vaccination and Health Care Access among Adults in the United States

Few studies have investigated the relationship between influenza vaccination and health care access. Furthermore, despite the well-documented disparities in vaccine coverage for communities of color, few studies have examined how experiences of discrimination may influence vaccine uptake. To fill this gap in the literature, this study examined associations between 5-year influenza vaccination rates and sociodemographic characteristics, health care access, and racial discrimination. Age, race/ethnicity, education, health care coverage, primary care provider, no medical care due to cost, and routine doctor checkups were significant correlates of 5-year influenza vaccination. In contrast to previous studies, discrimination scores were not a significant correlate of regular influenza vaccination. Respondents who reported forgoing care due to cost were less likely to report vaccination every year out of the last 5 years compared to all of the less frequent categories combined, demonstrating a more complex association between sometimes not being able to afford medical care and influenza vaccination. Future research should examine the relationship between influenza vaccination uptake, racial discrimination, and forgone care due to cost to enhance resources and messaging for influenza vaccination uptake