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Sökning: WFRF:(Yan J) > Luleå tekniska universitet

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2.
  • Bentham, James, et al. (författare)
  • A century of trends in adult human height
  • 2016
  • Ingår i: eLIFE. - : eLife Sciences Publications Ltd. - 2050-084X. ; 5
  • Tidskriftsartikel (refereegranskat)abstract
    • Being taller is associated with enhanced longevity, and higher education and earnings. We reanalysed 1472 population-based studies, with measurement of height on more than 18.6 million participants to estimate mean height for people born between 1896 and 1996 in 200 countries. The largest gain in adult height over the past century has occurred in South Korean women and Iranian men, who became 20.2 cm (95% credible interval 17.5–22.7) and 16.5 cm (13.3– 19.7) taller, respectively. In contrast, there was little change in adult height in some sub-Saharan African countries and in South Asia over the century of analysis. The tallest people over these 100 years are men born in the Netherlands in the last quarter of 20th century, whose average heights surpassed 182.5 cm, and the shortest were women born in Guatemala in 1896 (140.3 cm; 135.8– 144.8). The height differential between the tallest and shortest populations was 19-20 cm a century ago, and has remained the same for women and increased for men a century later despite substantial changes in the ranking of countries.
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3.
  • Zhou, Bin, et al. (författare)
  • Worldwide trends in diabetes since 1980: A pooled analysis of 751 population-based studies with 4.4 million participants
  • 2016
  • Ingår i: The Lancet. - : Elsevier B.V.. - 0140-6736 .- 1474-547X. ; 387:10027, s. 1513-1530
  • Tidskriftsartikel (refereegranskat)abstract
    • Background: One of the global targets for non-communicable diseases is to halt, by 2025, the rise in the age standardised adult prevalence of diabetes at its 2010 levels. We aimed to estimate worldwide trends in diabetes, how likely it is for countries to achieve the global target, and how changes in prevalence, together with population growth and ageing, are aff ecting the number of adults with diabetes.Methods: We pooled data from population-based studies that had collected data on diabetes through measurement of its biomarkers. We used a Bayesian hierarchical model to estimate trends in diabetes prevalence-defined as fasting plasma glucose of 7.0 mmol/L or higher, or history of diagnosis with diabetes, or use of insulin or oral hypoglycaemic drugs-in 200 countries and territories in 21 regions, by sex and from 1980 to 2014. We also calculated the posterior probability of meeting the global diabetes target if post-2000 trends continue.Findings: We used data from 751 studies including 4372000 adults from 146 of the 200 countries we make estimates for. Global age-standardised diabetes prevalence increased from 4.3% (95% credible interval 2.4-17.0) in 1980 to 9.0% (7.2-11.1) in 2014 in men, and from 5.0% (2.9-7.9) to 7.9% (6.4-9.7) in women. The number of adults with diabetes in the world increased from 108 million in 1980 to 422 million in 2014 (28.5% due to the rise in prevalence, 39.7% due to population growth and ageing, and 31.8% due to interaction of these two factors). Age-standardised adult diabetes prevalence in 2014 was lowest in northwestern Europe, and highest in Polynesia and Micronesia, at nearly 25%, followed by Melanesia and the Middle East and north Africa. Between 1980 and 2014 there was little change in age-standardised diabetes prevalence in adult women in continental western Europe, although crude prevalence rose because of ageing of the population. By contrast, age-standardised adult prevalence rose by 15 percentage points in men and women in Polynesia and Micronesia. In 2014, American Samoa had the highest national prevalence of diabetes (>30% in both sexes), with age-standardised adult prevalence also higher than 25% in some other islands in Polynesia and Micronesia. If post-2000 trends continue, the probability of meeting the global target of halting the rise in the prevalence of diabetes by 2025 at the 2010 level worldwide is lower than 1% for men and is 1% for women. Only nine countries for men and 29 countries for women, mostly in western Europe, have a 50% or higher probability of meeting the global target.Interpretation: Since 1980, age-standardised diabetes prevalence in adults has increased, or at best remained unchanged, in every country. Together with population growth and ageing, this rise has led to a near quadrupling of the number of adults with diabetes worldwide. The burden of diabetes, both in terms of prevalence and number of adults aff ected, has increased faster in low-income and middle-income countries than in high-income countries.
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4.
  • Baran, J. D., et al. (författare)
  • Theoretical and experimental comparison of SnPc, PbPc, and CoPc adsorption on Ag(111)
  • 2010
  • Ingår i: Physical Review B (Condensed Matter and Materials Physics). - 1098-0121 .- 1550-235X. ; 81:7
  • Tidskriftsartikel (refereegranskat)abstract
    • A combination of normal-incidence x-ray standing-wave (NIXSW) spectroscopy, x-ray photoelectron spectroscopy (XPS), scanning tunneling microscopy (STM), and density-functional theory (DFT) has been used to investigate the interaction of a number of phthalocyanine molecules (specifically, SnPc, PbPc, and CoPc) with the Ag(111) surface. The metal-surface distances predicted by the DFT calculations for SnPc/Ag(111) (2.48 angstrom) and CoPc/Ag(111) (2.88 angstrom) are in good agreement with our NIXSW experimental results for these systems (2.31 +/- 0.09 and 2.90 +/- 0.05 angstrom, respectively). Good agreement is also found between calculated partial density-of-states plots and STM images of CoPc on Ag(111). Although the DFT and Pb 4f NIXSW results for the Pb-Ag(111) distance are similarly in apparently good agreement, the Pb 4f core-level data suggest that a chemical reaction between PbPc and Ag(111) occurs due to the annealing procedure used in our experiments and that the similarity of the DFT and Pb 4f NIXSW values for the Pb-Ag(111) distance is likely to be fortuitous. We interpret the Pb 4f XPS data as indicating that the Pb atom can detach from the PbPc molecule when it is adsorbed in the "Pb-down" position, leading to the formation of a Pb-Ag alloy and the concomitant reduction in Pb from a Pb2+ state (in bulklike films of PbPc) to Pb-0. In contrast to SnPc, neither PbPc nor CoPc forms a well-ordered monolayer on Ag(111) via the deposition and annealing procedures we have used. Our DFT calculations show that each of the phthalocyanine molecules donate charge to the silver surface, and that back donation from Ag to the metal atom (Co, Sn, or Pb) is only significant for CoPc.
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5.
  • Baran, Jakub D., et al. (författare)
  • DFT Computation Of Metal-Phthalocyanines Bonded To Ag(111)
  • 2007
  • Konferensbidrag (refereegranskat)abstract
    • To study the adsorption of metal-phthalocyanines (MPc (M=Co; Sn; Pb) on the Ag(111) surface we have performed electronic structure calculations using a cluster representation of the surface within the framework of density functional theory (DFT) [1]. Our calculations use the generalized gradient approximation (GGA) parameterization by Pedrew-Burke-Ernzerhof (PBE) for the exchange-correlation energy [2]. We have investigated bonding on three surface adsorption sites (hcp-hollow; fcc-hollow and on-top). SnPc was found to adsorb weakly to the surface (0.15 to 0.25 eV); and to prefer hollow bonding rather than on-top bonding. The distance between the Sn atom and the top layer Ag-surface atoms (hcp-hollow and fcc-hollow) is consistent with experimental data obtained by normal incidence X-ray standing wave spectroscopy (NIXSW) [3;4]. CoPc is much more strongly bound to the Ag(111) surface and was found to prefer the on-top site. The calculated binding energy is 1.2 eV and the distance between the Co atom and the top layer Ag atoms is 3 (which also matched the experimental data well). For PbPc; successful adsorption was only obtained on the hcp-hollow site with a binding energy of 0.5 eV. For each of these systems we have found good agreement in binding geometries with experimental data.
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6.
  • Baran, Jakub D., et al. (författare)
  • Interactions of Metal-phthalocyanines MPc (M=Co; Sn; Pb) with Silver Surface Ag(111) : A Density Functional Study
  • 2008
  • Konferensbidrag (refereegranskat)abstract
    • Deposited and/or self-assembled on metal electrodes; metal-phthalocyanine are attractive candidates for novel molecular sensors; memory; and light-harvesting components. The knowledge of the their molecular geometry and electronic structure are crucial points in order to understand their interactions with surfaces. To study the adsorption of metal-phthalocyanines (MPc (M=Co; Sn; Pb) bonded parallel on the Ag(111) surface we have performed electronic structure calculations using a cluster representation (55 and 169 silver atoms) of the surface within the framework of density functional theory (DFT) [1]. Our calculations use the generalized gradient approximation (GGA) parameterization by Pedrew-Burke-Ernzerhof (PBE) for the exchange-correlation energy [2] and multipole accelerated resolution of identity method [3]. We have investigated bonding on three surface adsorption sites (hcp-hollow; fcc-hollow and on-top). For each of these systems we have found good agreement in binding geometries with experimental data obtained by normal incidence X-ray standing wave spectroscopy (NIXSW) [4;5]. Binding energies and geometries for all systems are given. We propose flat chemisorption of respective MPcs on Ag(111).
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8.
  • Prabowo, Bayu, et al. (författare)
  • CO2–steam mixture for direct and indirect gasification of rice straw in a downdraft gasifier : Laboratory-scale experiments and performance prediction
  • 2014
  • Ingår i: Applied Energy. - : Elsevier BV. - 0306-2619 .- 1872-9118. ; 113, s. 670-679
  • Tidskriftsartikel (refereegranskat)abstract
    • This paper explored the feasibility of CO2 as alternative gasifying agent of steam to obtain higher thermal efficiency in biomass gasification. The effect of the gasifying agent on gas evolution and thermal efficiency was examined by using a lab scale downdraft gasifier. The results were also compared with the output of pyrolysis with N2. The reaction atmosphere in indirect and direct gasification was simulated by carrying out the experiments without and with O2 presence. The reaction conditions were varied in the temperature range from 750 °C to 950 °C by changing the CO2 molar fraction in gasifying agent to the ratio of 0, 30 and 60 vol.% in balance with steam. 40 vol.% of N2 fraction was kept during O2 free experiments, while 31.7 vol.% of N2 and 8.3 vol.% O2 were kept during the experiments with the presence of O2. At all examined condition, gasification yielded more combustible gas than pyrolysis. Furthermore, high CO2 fraction in gasifying agent generally resulted in low H2 yield and high CO yield. These substitutions mostly lowered the energy yield of the producer gas, but in the other hand also reduced the preheating energy of gasifying agent. Thus, optimizations of these changes were investigated for gaining highest thermal efficiency of the gasification process. Highest thermal efficiency of the process without O2 was 52% under N2 (40 vol.%)–CO2 (60 vol.%) atmosphere at the temperature of 850 °C. For the process with O2, where the part of gasifying agent preheating energy supplied by the biomass partial combustion, the highest thermal efficiency was 60% under the CO2 (60 vol.%)–O2 (8.3 vol.%)–N2 (31.7 vol.%) atmosphere at the temperature of 950 °C. CO2 utilization as a gasifying agent potentially increases the thermal efficiency of biomass conversion process compared with pyrolysis or conventional indirect and direct gasification, i.e. pure-steam gasification and O2–steam gasification.
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9.
  • Wolf, J., et al. (författare)
  • Comparison of nickel- and iron-based oxygen carriers in chemical looping combustion for CO2 capture in power generation
  • 2005
  • Ingår i: Fuel. - : Elsevier BV. - 0016-2361 .- 1873-7153. ; 84:7-8, s. 993-1006
  • Tidskriftsartikel (refereegranskat)abstract
    • In chemical looping combustion (CLC), a solid oxygen carrier circulates between two fluidised bed reactors and transports oxygen from the combustion air to the fuel: thus, the fuel is not mixed with air and an inherent CO2 separation occurs. In this paper, CLC is integrated in a natural gas fired combined cycle (NGCC). In this system, nickel- and iron-based oxygen carriers are compared regarding the system's electrical and exergy efficiencies. Furthermore, the feasibility of CLC in two interconnected pressurised fluidised bed reactors (IPFBR) is studied for both oxygen carriers. The hypothetical layout plus dimensions of the IPFBR is presented for a capacity of 800 MW input of natural gas. Finally, top-firing is proposed as an option to overcome the apparent limitation in operating temperature of the reactor equipment and/or the oxygen carriers. The results indicate that there is no significant difference in the system's efficiency if both oxygen carriers could operate at the same temperature. However, CLC seems easier to be technically realised in an IPFBR with a nickel-based oxygen carrier.
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10.
  • Wolf, J., et al. (författare)
  • Parametric study of chemical looping combustion for tri-generation of hydrogen, heat, and electrical power with CO2 capture
  • 2005
  • Ingår i: International Journal of Energy Research. - : Hindawi Limited. - 0363-907X .- 1099-114X. ; 29:8, s. 739-753
  • Tidskriftsartikel (refereegranskat)abstract
    • In this article, a novel cycle configuration has been studied, termed the extended chemical looping combustion integrated in a steam-injected gas turbine cycle. The products of this system are hydrogen, heat, and electrical power. Furthermore, the system inherently separates the CO2 and hydrogen that is produced during the combustion. The core process is an extended chemical looping combustion (exCLC) process which is based on classical chemical looping combustion (CLC). In classical CLC, a solid oxygen carrier circulates between two fluidized bed reactors and transports oxygen from the combustion air to the fuel; thus, the fuel is not mixed with air and an inherent CO2 separation occurs. In exCLC the oxygen carrier circulates along with a carbon carrier between three fluidized bed reactors, one to oxidize the oxygen carrier, one to produces and separate the hydrogen, and one to regenerate the carbon carrier. The impacts of process parameters, such as flowrates and temperatures have been studied on the efficiencies of producing electrical power, hydrogen, and district heating and on the degree of capturing CO2. The result shows that this process has the potential to achieve a thermal efficiency of 54% while 96% of the CO2 is captured and compressed to 110 bar.
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