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| 6. |
- Kristan, Matej, et al.
(författare)
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The first visual object tracking segmentation VOTS2023 challenge results
- 2023
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Ingår i: 2023 IEEE/CVF International conference on computer vision workshops (ICCVW). - : Institute of Electrical and Electronics Engineers Inc.. - 9798350307443 - 9798350307450 ; , s. 1788-1810
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Konferensbidrag (refereegranskat)abstract
- The Visual Object Tracking Segmentation VOTS2023 challenge is the eleventh annual tracker benchmarking activity of the VOT initiative. This challenge is the first to merge short-term and long-term as well as single-target and multiple-target tracking with segmentation masks as the only target location specification. A new dataset was created; the ground truth has been withheld to prevent overfitting. New performance measures and evaluation protocols have been created along with a new toolkit and an evaluation server. Results of the presented 47 trackers indicate that modern tracking frameworks are well-suited to deal with convergence of short-term and long-term tracking and that multiple and single target tracking can be considered a single problem. A leaderboard, with participating trackers details, the source code, the datasets, and the evaluation kit are publicly available at the challenge website1
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| 7. |
- Kristanl, Matej, et al.
(författare)
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The Seventh Visual Object Tracking VOT2019 Challenge Results
- 2019
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Ingår i: 2019 IEEE/CVF INTERNATIONAL CONFERENCE ON COMPUTER VISION WORKSHOPS (ICCVW). - : IEEE COMPUTER SOC. - 9781728150239 ; , s. 2206-2241
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Konferensbidrag (refereegranskat)abstract
- The Visual Object Tracking challenge VOT2019 is the seventh annual tracker benchmarking activity organized by the VOT initiative. Results of 81 trackers are presented; many are state-of-the-art trackers published at major computer vision conferences or in journals in the recent years. The evaluation included the standard VOT and other popular methodologies for short-term tracking analysis as well as the standard VOT methodology for long-term tracking analysis. The VOT2019 challenge was composed of five challenges focusing on different tracking domains: (i) VOT-ST2019 challenge focused on short-term tracking in RGB, (ii) VOT-RT2019 challenge focused on "real-time" short-term tracking in RGB, (iii) VOT-LT2019 focused on long-term tracking namely coping with target disappearance and reappearance. Two new challenges have been introduced: (iv) VOT-RGBT2019 challenge focused on short-term tracking in RGB and thermal imagery and (v) VOT-RGBD2019 challenge focused on long-term tracking in RGB and depth imagery. The VOT-ST2019, VOT-RT2019 and VOT-LT2019 datasets were refreshed while new datasets were introduced for VOT-RGBT2019 and VOT-RGBD2019. The VOT toolkit has been updated to support both standard short-term, long-term tracking and tracking with multi-channel imagery. Performance of the tested trackers typically by far exceeds standard baselines. The source code for most of the trackers is publicly available from the VOT page. The dataset, the evaluation kit and the results are publicly available at the challenge website(1).
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| 8. |
- QingMiao, Hu, et al.
(författare)
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Composition dependent elastic modulus and phase stability of Ni2MnGa based ferromagnetic shape memory alloys
- 2012
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Ingår i: SCI CHINA TECHNOL SC. - : Springer Science and Business Media LLC. - 1674-7321 .- 1869-1900. ; 55:2, s. 295-305
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Tidskriftsartikel (refereegranskat)abstract
- Ni2MnGa based ferromagnetic alloys are ideal candidates for applications such as actuators, magnetic refrigerators or magnetostrictive transducers due to their attractive properties such as magnetic field induced shape memory effect and large magnetocaloric effect. The properties of these alloys (e.g., the martensitic transformation temperature T (M) ) sensitively depend on the composition. Understanding the composition dependence of these properties so as to design the alloy as desired is one of the main research topics in this area. In recent years, we have investigated the composition dependent elastic modulus and phase stability of Ni2MnGa-based alloys by using a first-principles method, in hope of clarifying their connection to the properties of these alloys. In this article, we review the main results of our investigations. We show that the tetragonal shear modulus C' is a better predictor of the composition dependent T (M) than the number of valence electrons per atom (e/a) since the general T (M) similar to C' correlation works for some of the alloys for which the T (M) similar to e/a correlation fails, although there exist several cases for which both the general T (M) similar to C' and T (M)similar to e/a correlations break down. Employing the experimentally determined modulation function, the complex 5-layer modulated (5M) structure of the martensite of Ni2MnGa and the Al-doping effect on it are studied. We find that the shuffle and shear of the 5M structure are linearly coupled. The relative stability of the austenite and the martensites is examined by comparing their total energies. The non-modulated martensite beta aEuro(3)aEuro(2) with the tetragonality of the unit cell c/a > 1 is shown to be globally stable whereas the 5M martensite with c/a < 1 is metastable. The critical Al atomic fraction over which the martensitic transformation between the 5M martensite and austenite cannot occur is predicted to be 0.26, in reasonable agreement with experimental findings.
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| 9. |
- Wang, Siqi, et al.
(författare)
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Adjusting Competitive Reaction to Control Nucleation and Growth of MnO2 for a High-Stress Output Electrochemical Actuator
- 2023
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Ingår i: ACS APPLIED ELECTRONIC MATERIALS. - : AMER CHEMICAL SOC. - 2637-6113. ; 5:9, s. 4836-4845
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Tidskriftsartikel (refereegranskat)abstract
- Manganese dioxide (MnO2) with biocompatibility has promising applications in low-voltage electrochemical actuators of implantable medical devices, which can convert electrical energy to mechanical motion. However, the unsatisfactory actuation strain restricts the generation of a larger output stress of MnO2 for practical application. Herein, a competitive reaction-driven-MnO2 (CRD-MnO2) nanorod network was fabricated on a nickel (Ni) thin-film substrate by adjusting the component molar ratios. We find that the competitive reaction between 3,4-ethylene-dioxythiophene (EDOT) polymerization and oxidation of Mn2+ controls the nucleation and growth behavior of MnO2. The variation in the electron environment, newly generated oxygen vacancies, and a higher content of structural water effectively improve the electroactivity of MnO2 and simultaneously cause more serious Jahn-Teller (JT) distortion of the crystal octahedrons. Thus, an excellent output performance simultaneously having a much higher actuating strain of 8.3% and an actuation stress of 390.1 MPa is generated during a redox reaction between Mn4+ and Mn3+ under 0-1 V. Moreover, the CRD-MnO2/Ni composite actuating films assembled on a 3D-printed resin model of a human hand with separated finger joints can perform smooth grasping and releasing actions, demonstrating a huge potential for in vitro rehabilitation exercises and implantability for people with finger dyskinesia. This work provides a strategy for actuator material fabrication by controlling a nucleation and growth process by adjusting a competitive reaction.
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| 10. |
- Zhang, Shuangshuang, et al.
(författare)
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Discovery of carbon-based strongest and hardest amorphous material
- 2022
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Ingår i: National Science Review. - : Oxford University Press. - 2095-5138 .- 2053-714X. ; 9:1
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Tidskriftsartikel (refereegranskat)abstract
- Carbon is one of the most fascinating elements due to its structurally diverse allotropic forms stemming from its bonding varieties (sp, sp2, and sp3). Exploring new forms of carbon has always been the eternal theme of scientific research. Herein, we report the amorphous (AM) carbon materials with high fraction of sp3 bonding recovered from compression of fullerene C60 under high pressure and high temperature previously unexplored. Analysis of photoluminescence and absorption spectra demonstrates that they are semiconducting with a bandgap range of 1.5–2.2 eV, comparable to that of widely used amorphous silicon. Comprehensive mechanical tests demonstrate that the synthesized AM-III carbon is the hardest and strongest amorphous material known so far, which can scratch diamond crystal and approach its strength. The produced AM carbon materials combine outstanding mechanical and electronic properties, and may potentially be used in photovoltaic applications that require ultrahigh strength and wear resistance.
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| 11. |
- Abdoullaye, Doukary, et al.
(författare)
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Permanent genetic resources added to molecular ecology resources database 1 August 2009 - 30 September 2009
- 2010
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Ingår i: Molecular Ecology Resources. - : Wiley. - 1755-098X .- 1755-0998. ; 10:1, s. 232-236
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Tidskriftsartikel (refereegranskat)abstract
- This article documents the addition of 238 microsatellite marker loci and 72 pairs of Single Nucleotide Polymorphism (SNP) sequencing primers to the Molecular Ecology Resources Database. Loci were developed for the following species: Adelges tsugae, Artemisia tridentata, Astroides calycularis, Azorella selago, Botryllus schlosseri, Botrylloides violaceus, Cardiocrinum cordatum var. glehnii, Campylopterus curvipennis, Colocasia esculenta, Cynomys ludovicianus, Cynomys leucurus, Cynomys gunnisoni, Epinephelus coioides, Eunicella singularis, Gammarus pulex, Homoeosoma nebulella, Hyla squirella, Lateolabrax japonicus, Mastomys erythroleucus, Pararge aegeria, Pardosa sierra, Phoenicopterus ruber ruber and Silene latifolia. These loci were cross-tested on the following species: Adelges abietis, Adelges cooleyi, Adelges piceae, Pineus pini, Pineus strobi, Tubastrea micrantha, three other Tubastrea species, Botrylloides fuscus, Botrylloides simodensis, Campylopterus hemileucurus, Campylopterus rufus, Campylopterus largipennis, Campylopterus villaviscensio, Phaethornis longuemareus, Florisuga mellivora, Lampornis amethystinus, Amazilia cyanocephala, Archilochus colubris, Epinephelus lanceolatus, Epinephelus fuscoguttatus, Symbiodinium temperate-A clade, Gammarus fossarum, Gammarus roeselii, Dikerogammarus villosus and Limnomysis benedeni. This article also documents the addition of 72 sequencing primer pairs and 52 allele specific primers for Neophocaena phocaenoides.
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| 12. |
- Arndt, D. S., et al.
(författare)
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State of the Climate in 2016
- 2017
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Ingår i: Bulletin of The American Meteorological Society - (BAMS). - 0003-0007 .- 1520-0477. ; 98:8, s. S1-S280
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Tidskriftsartikel (refereegranskat)abstract
- In 2016, the dominant greenhouse gases released into Earth's atmosphere-carbon dioxide, methane, and nitrous oxide-continued to increase and reach new record highs. The 3.5 +/- 0.1 ppm rise in global annual mean carbon dioxide from 2015 to 2016 was the largest annual increase observed in the 58-year measurement record. The annual global average carbon dioxide concentration at Earth's surface surpassed 400 ppm (402.9 +/- 0.1 ppm) for the first time in the modern atmospheric measurement record and in ice core records dating back as far as 800000 years. One of the strongest El Nino events since at least 1950 dissipated in spring, and a weak La Nina evolved later in the year. Owing at least in part to the combination of El Nino conditions early in the year and a long-term upward trend, Earth's surface observed record warmth for a third consecutive year, albeit by a much slimmer margin than by which that record was set in 2015. Above Earth's surface, the annual lower troposphere temperature was record high according to all datasets analyzed, while the lower stratospheric temperature was record low according to most of the in situ and satellite datasets. Several countries, including Mexico and India, reported record high annual temperatures while many others observed near-record highs. A week-long heat wave at the end of April over the northern and eastern Indian peninsula, with temperatures surpassing 44 degrees C, contributed to a water crisis for 330 million people and to 300 fatalities. In the Arctic the 2016 land surface temperature was 2.0 degrees C above the 1981-2010 average, breaking the previous record of 2007, 2011, and 2015 by 0.8 degrees C, representing a 3.5 degrees C increase since the record began in 1900. The increasing temperatures have led to decreasing Arctic sea ice extent and thickness. On 24 March, the sea ice extent at the end of the growth season saw its lowest maximum in the 37-year satellite record, tying with 2015 at 7.2% below the 1981-2010 average. The September 2016 Arctic sea ice minimum extent tied with 2007 for the second lowest value on record, 33% lower than the 1981-2010 average. Arctic sea ice cover remains relatively young and thin, making it vulnerable to continued extensive melt. The mass of the Greenland Ice Sheet, which has the capacity to contribute similar to 7 m to sea level rise, reached a record low value. The onset of its surface melt was the second earliest, after 2012, in the 37-year satellite record. Sea surface temperature was record high at the global scale, surpassing the previous record of 2015 by about 0.01 degrees C. The global sea surface temperature trend for the 21st century-to-date of +0.162 degrees C decade(-1) is much higher than the longer term 1950-2016 trend of +0.100 degrees C decade(-1). Global annual mean sea level also reached a new record high, marking the sixth consecutive year of increase. Global annual ocean heat content saw a slight drop compared to the record high in 2015. Alpine glacier retreat continued around the globe, and preliminary data indicate that 2016 is the 37th consecutive year of negative annual mass balance. Across the Northern Hemisphere, snow cover for each month from February to June was among its four least extensive in the 47-year satellite record. Continuing a pattern below the surface, record high temperatures at 20-m depth were measured at all permafrost observatories on the North Slope of Alaska and at the Canadian observatory on northernmost Ellesmere Island. In the Antarctic, record low monthly surface pressures were broken at many stations, with the southern annular mode setting record high index values in March and June. Monthly high surface pressure records for August and November were set at several stations. During this period, record low daily and monthly sea ice extents were observed, with the November mean sea ice extent more than 5 standard deviations below the 1981-2010 average. These record low sea ice values contrast sharply with the record high values observed during 2012-14. Over the region, springtime Antarctic stratospheric ozone depletion was less severe relative to the 1991-2006 average, but ozone levels were still low compared to pre-1990 levels. Closer to the equator, 93 named tropical storms were observed during 2016, above the 1981-2010 average of 82, but fewer than the 101 storms recorded in 2015. Three basins-the North Atlantic, and eastern and western North Pacific-experienced above-normal activity in 2016. The Australian basin recorded its least active season since the beginning of the satellite era in 1970. Overall, four tropical cyclones reached the Saffir-Simpson category 5 intensity level. The strong El Nino at the beginning of the year that transitioned to a weak La Nina contributed to enhanced precipitation variability around the world. Wet conditions were observed throughout the year across southern South America, causing repeated heavy flooding in Argentina, Paraguay, and Uruguay. Wetter-than-usual conditions were also observed for eastern Europe and central Asia, alleviating the drought conditions of 2014 and 2015 in southern Russia. In the United States, California had its first wetter-than-average year since 2012, after being plagued by drought for several years. Even so, the area covered by drought in 2016 at the global scale was among the largest in the post-1950 record. For each month, at least 12% of land surfaces experienced severe drought conditions or worse, the longest such stretch in the record. In northeastern Brazil, drought conditions were observed for the fifth consecutive year, making this the longest drought on record in the region. Dry conditions were also observed in western Bolivia and Peru; it was Bolivia's worst drought in the past 25 years. In May, with abnormally warm and dry conditions already prevailing over western Canada for about a year, the human-induced Fort McMurray wildfire burned nearly 590000 hectares and became the costliest disaster in Canadian history, with $3 billion (U.S. dollars) in insured losses.
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| 13. |
- Arndt, D. S., et al.
(författare)
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STATE OF THE CLIMATE IN 2017
- 2018
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Ingår i: Bulletin of The American Meteorological Society - (BAMS). - : American Meteorological Society. - 0003-0007 .- 1520-0477. ; 99:8, s. S1-S310
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Forskningsöversikt (refereegranskat)
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| 14. |
- Bao, Fanglin, et al.
(författare)
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First-order correction to the Casimir force within an inhomogeneous medium
- 2015
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Ingår i: Physical Review A. Atomic, Molecular, and Optical Physics. - 1050-2947 .- 1094-1622. ; 91:6
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Tidskriftsartikel (refereegranskat)abstract
- For the Casimir piston filled with an inhomogeneous medium, we regularized and expressed the Casimir energy with cylinder kernel coefficients by using the first-order perturbation theory. When the refractive index of the medium is smoothly inhomogeneous (i.e., derivatives of all orders exist), a logarithmically cutoff-dependent term and a quadratically cutoff-dependent term in the Casimir energy are found. We show that in the piston model these terms vanish in the force and thus the Casimir force is always cutoff independent, but these terms will remain in the force in the half-space model and must be removed by additional regularizations. We give explicit benchmark solutions to the first-order corrections of both Casimir energy and Casimir force for an exponentially decaying profile. The present method can be extended to other inhomogeneous profiles. Our results should be useful for future relevant calculations and experimental studies.
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| 15. |
- Bauer, Franz E., et al.
(författare)
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A new, faint population of X-ray transients
- 2017
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Ingår i: Monthly Notices of the Royal Astronomical Society. - : Oxford University Press (OUP). - 0035-8711 .- 1365-2966. ; 467:4, s. 4841-4857
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Tidskriftsartikel (refereegranskat)abstract
- We report on the detection of a remarkable new fast high-energy transient found in the Chandra Deep Field-South, robustly associated with a faint (mR = 27.5mag, zph ~2.2) host in the CANDELS survey. The X-ray event is comprised of 115+12 -11 net 0.3-7.0 keV counts, with a light curve characterized by an ~100 s rise time, a peak 0.3-10 keV flux of ~5 × 10-12 erg s-1 cm-2 and a power-law decay time slope of -1.53 ± 0.27. The average spectral slope is Γ = 1.43+0.23 -0.13, with no clear spectral variations. The X-ray and multiwavelength properties effectively rule out the vast majority of previously observed highenergy transients. A few theoretical possibilities remain: an 'orphan' X-ray afterglow from an off-axis short-duration gamma-ray burst (GRB) with weak optical emission, a low-luminosity GRB at high redshift with no prompt emission below ~20 keV rest frame, or a highly beamed tidal disruption event (TDE) involving an intermediate-mass black hole and a white dwarf with little variability. However, none of the above scenarios can completely explain all observed properties. Although large uncertainties exist, the implied rate of such events is comparable to those of orphan and low-luminosity GRBs as well as rare TDEs, implying the discovery of an untapped regime for a known transient class, or a new type of variable phenomena whose nature remains to be determined.
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| 16. |
- Carlegrim, Elin, et al.
(författare)
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Near-edge x-ray absorption studies of Na-doped tetracyanoethylene films : A model system for the V(TCNE)x room-temperature molecular magnet
- 2008
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Ingår i: Physical Review B. Condensed Matter and Materials Physics. - : Institutionen för teknik och naturvetenskap. - 1098-0121 .- 1550-235X. ; 77:5, s. 054420-1-054420-8
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Tidskriftsartikel (refereegranskat)abstract
- V(TCNE)(x), with TCNE=tetracyanoethylene and x similar to 2, is an organic-based molecular magnet with potential to be used in spintronic devices. With the aim of shedding light on the unoccupied frontier electronic structure of V(TCNE)(x) we have studied pristine TCNE and sodium-intercalated TCNE by near edge x-ray absorption fine structure (NEXAFS) spectroscopy as well as with theoretical calculations. Sodium-intercalated TCNE was used as a model system of the more complex V(TCNE)(x) and both experimental and theoretical results of the model compound have been used to interpret the NEXAFS spectra of V(TCNE)(x). By comparing the experimental and theoretical C K-edge of pristine TCNE, the contributions from the various carbon species (cyano and vinyl) could be disentangled. Upon fully sodium intercalation, TCNE is n doped with one electron per molecule and the features in the C and N K-edge spectra of pristine TCNE undergo strong modification caused by partially filling the TCNE lowest unoccupied molecular orbital (LUMO). When comparing the C and N K-edge NEXAFS spectra of fully sodium-doped TCNE with V(TCNE)(x), the spectra are similar except for broadening of the features which originates from structural disorder of the V(TCNE)(x) films. The combined results from the model system and V(TCNE)(x) suggest that the lowest unoccupied molecular orbital with density on the nitrogen atoms in V(TCNE)(x) has no significant hybridization with vanadium and is similar to the so-called singly occupied molecular orbital of the TCNE anion. This suggests that the LUMO of V(TCNE)(x) is TCNE- or vanadiumlike, in contrast to the frontier occupied electronic structure where the highest occupied molecular orbital is a hybridization between V(3d) and cyano carbons. The completely different nature of the unoccupied and occupied frontier electronic structure of the material will most likely affect both charge injection and transport properties of a spintronic device featuring V(TCNE)(x).
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| 17. |
- Deng, Bin, et al.
(författare)
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Modelling asymmetric deformation along a curved strike-slip basement-fault system
- 2021
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Ingår i: International journal of earth sciences. - : Springer. - 1437-3254 .- 1437-3262. ; 110, s. 165-182
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Tidskriftsartikel (refereegranskat)abstract
- Large-scale curved strike-slip fault systems along which significant amounts of displacement have taken place are common in nature. Scaled analogue experiments were used in this study to investigate strike-slip deformation in cover units above a curved basement-fault system simulated by a rigid plate with an in-built curvature depicting a half-circular fault. The model results show that en-echelon, right-stepping Riedel shears and low-angle synthetic shears (Y-shears) always form at the beginning of deformation, and grow outwards with splay faults, most of which evolve into thrusts at later stages of deformation. Digital image correlation (DIC) analyses of the surface displacement vectors show that a diffuse zone of deformation progressively changes into en-echelon shears, which gradually develop into throughgoing shear zones with further deformation. The geometries of Riedel shears along two sides of the basement fault (i.e. concave and convex sides) show significant differences in fault shape and intersection angles between the faults and the curved basement fault, indicating an asymmetry in deformation with a much wider deformation zone occurring on the concave side. As a result, en-echelon and/or overlapping flower structures develop along the curved basement strike-slip fault system. In particular, Riedel shears with a upward-convex geometry are localised in both sides of the curved basement fault and a continuous reverse oblique-slip fault forms at the concave side. When compared with the geometry of curved strike-slip faults in nature (e.g. the Daliangshan shear zone in Xichang basin and the Red River shear zone in the Yinggehai basin, China) the model results depict the asymmetric evolution pattern of the faults on either side of curved basement faults.
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| 18. |
- Deng, Yunfeng, et al.
(författare)
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A comparative theoretical study on core-hole excitation spectra of azafullerene and its derivatives
- 2014
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Ingår i: Journal of Chemical Physics. - : AIP Publishing. - 0021-9606 .- 1089-7690. ; 140:12, s. 124304-
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Tidskriftsartikel (refereegranskat)abstract
- The core-hole excitation spectra-near-edge x-ray absorption spectroscopy (NEXAFS), x-ray emission spectroscopy (XES), and x-ray photoelectron spectroscopy (XPS) shake-up satellites have been simulated at the level of density functional theory for the azafullerene C59N and its derivatives (C59N)(+), C59HN, (C59N)(2), and C59N-C-60, in which the XPS shake-up satellites were simulated using our developed equivalent core hole Kohn-Sham(ECH-KS) density functional theory approach [B. Gao, Z. Wu, and Y. Luo, J. Chem. Phys. 128, 234704 (2008)] which aims for the study of XPS shake-up satellites of large-scale molecules. Our calculated spectra are generally in good agreement with available experimental results that validates the use of the ECH-KS method in the present work. The nitrogen K-edge NEXAFS, XES, and XPS shake-up satellites spectra in general can be used as fingerprints to distinguish the azafullerene C59N and its different derivatives. Meanwhile, different carbon K-edge spectra could also provide detailed information of (local) electronic structures of different molecules. In particular, a peak (at around 284.5 eV) in the carbon K-edge NEXAFS spectrum of the heterodimer C59N-C-60 is confirmed to be related to the electron transfer from the C59N part to the C-60 part in this charge-transfer complex.
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| 19. |
- Ding, Sunjia, et al.
(författare)
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Boosting enzymatic degradation of cellulose using a fungal expansin : Structural insight into the pretreatment mechanism
- 2022
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Ingår i: Bioresource Technology. - : Elsevier. - 0960-8524 .- 1873-2976. ; 358
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Tidskriftsartikel (refereegranskat)abstract
- The recalcitrance of cellulosic biomass greatly hinders its enzymatic degradation. Expansins induce cell wall loosening and promote efficient cellulose utilization; however, the molecular mechanism underlying their action is not well understood. In this study, TlEXLX1, a fungal expansin from Talaromyces leycettanus JCM12802, was characterized in terms of phylogeny, synergy, structure, and mechanism of action. TlEXLX1 displayed varying degrees of synergism with commercial cellulase in the pretreatment of corn straw and filter paper. TlEXLX1 binds to cellulose via domain 2, mediated by CH–π interactions with residues Tyr291, Trp292, and Tyr327. Residues Asp237, Glu238, and Asp248 in domain 1 form hydrogen bonds with glucose units and break the inherent hydrogen bonding within the cellulose matrix. This study identified the expansin amino acid residues crucial for cellulose binding, and elucidated the structure and function of expansins in cell wall networks; this has potential applications in biomass utilization.
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| 20. |
- Duan, Sai, et al.
(författare)
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A density functional theory approach to mushroom-like platinum clusters on palladium-shell over Au core nanoparticles for high electrocatalytic activity
- 2011
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Ingår i: Physical Chemistry, Chemical Physics - PCCP. - Cambridge : ROYAL SOC CHEMISTRY. - 1463-9076 .- 1463-9084. ; 13:12, s. 5441-5449
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Tidskriftsartikel (refereegranskat)abstract
- Recently, it was found that Pt clusters deposited on Pd shell over Au core nanoparticles (Au@Pd@Pt NPs) exhibit unusually high electrocatalytic activity for the electro-oxidation of formic acid (P. P. Fang, S. Duan, et al., Chem. Sci., 2011, 2, 531-539). In an attempt to offer an explanation, we used here carbon monoxide (CO) as probed molecules, and applied density functional theory (DFT) to simulate the surface Raman spectra of CO at this core-shell-cluster NPs with a two monolayer thickness of Pd shell and various Pt cluster coverage. Our DFT results show that the calculated Pt coverage dependent spectra fit the experimental ones well only if the Pt clusters adopt a mushroom-like structure, while currently the island-like structure is the widely accepted model, which follows the Volmer-Weber growth mode. This result infers that there should be a new growth mode, i.e., the mushroom growth mode as proposed in the present work, for Au@Pd@Pt NPs. We suggest that such a mushroom-like structure may offer novel active sites, which accounts for the observed high electrocatalytic activity of Au@Pd@Pt NPs.
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| 21. |
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| 22. |
- Feng, Ruizhi, et al.
(författare)
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Mutations in TUBB8 and Human Oocyte Meiotic Arrest.
- 2016
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Ingår i: The New England journal of medicine. - 1533-4406. ; 374:3, s. 223-232
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Tidskriftsartikel (refereegranskat)abstract
- Background Human reproduction depends on the fusion of a mature oocyte with a sperm cell to form a fertilized egg. The genetic events that lead to the arrest of human oocyte maturation are unknown. Methods We sequenced the exomes of five members of a four-generation family, three of whom had infertility due to oocyte meiosis I arrest. We performed Sanger sequencing of a candidate gene, TUBB8, in DNA samples from these members, additional family members, and members of 23 other affected families. The expression of TUBB8 and all other β-tubulin isotypes was assessed in human oocytes, early embryos, sperm cells, and several somatic tissues by means of a quantitative reverse-transcriptase-polymerase-chain-reaction assay. We evaluated the effect of the TUBB8 mutations on the assembly of the heterodimer consisting of one α-tubulin polypeptide and one β-tubulin polypeptide (α/β-tubulin heterodimer) in vitro, on microtubule architecture in HeLa cells, on microtubule dynamics in yeast cells, and on spindle assembly in mouse and human oocytes. Results We identified seven mutations in the primate-specific gene TUBB8 that were responsible for oocyte meiosis I arrest in 7 of the 24 families. TUBB8 expression is unique to oocytes and the early embryo, in which this gene accounts for almost all the expressed β-tubulin. The mutations affect chaperone-dependent folding and assembly of the α/β-tubulin heterodimer, disrupt microtubule behavior on expression in cultured cells, alter microtubule dynamics in vivo, and cause catastrophic spindle-assembly defects and maturation arrest on expression in mouse and human oocytes. Conclusions TUBB8 mutations have dominant-negative effects that disrupt microtubule behavior and oocyte meiotic spindle assembly and maturation, causing female infertility. (Funded by the National Basic Research Program of China and others.).
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| 23. |
- Földváry Ličina, Veronika, et al.
(författare)
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Development of the ASHRAE Global Thermal Comfort Database II
- 2018
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Ingår i: Building and Environment. - : Elsevier BV. - 0360-1323. ; 142, s. 502-512
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Tidskriftsartikel (refereegranskat)abstract
- Recognizing the value of open-source research databases in advancing the art and science of HVAC, in 2014 the ASHRAE Global Thermal Comfort Database II project was launched under the leadership of University of California at Berkeley's Center for the Built Environment and The University of Sydney's Indoor Environmental Quality (IEQ) Laboratory. The exercise began with a systematic collection and harmonization of raw data from the last two decades of thermal comfort field studies around the world. The ASHRAE Global Thermal Comfort Database II (Comfort Database), now an online, open-source database, includes approximately 81,846 complete sets of objective indoor climatic observations with accompanying “right-here-right-now” subjective evaluations by the building occupants who were exposed to them. The database is intended to support diverse inquiries about thermal comfort in field settings. A simple web-based interface to the database enables filtering on multiple criteria, including building typology, occupancy type, subjects' demographic variables, subjective thermal comfort states, indoor thermal environmental criteria, calculated comfort indices, environmental control criteria and outdoor meteorological information. Furthermore, a web-based interactive thermal comfort visualization tool has been developed that allows end-users to quickly and interactively explore the data.
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| 24. |
- Gao, Bin, et al.
(författare)
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A density functional theory study of shake-up satellites in photoemission of carbon fullerenes and nanotubes
- 2008
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Ingår i: Journal of Chemical Physics. - : AIP Publishing. - 0021-9606 .- 1089-7690. ; 128:23, s. 234704-1-234704-7
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Tidskriftsartikel (refereegranskat)abstract
- Carbon 1s shake-up spectra of fullerenes C-60, C-70, and C-82 and single-walled carbon nanotubes (SWCNTs) of (5,5), (6,5), and (7,6) have been investigated by using equivalent core hole Kohn-Sham density functional theory approach, in which only one-electron transition between molecular orbitals within core-hole potential is considered. The calculated spectra are generally in good agreement with results of equivalent core-hole time-dependent density functional theory calculations and available experiments, and reliable assignments for the complicated shake-up spectra of such large systems are provided. Calculations have also been performed for endohedral metallofullerene Gd@C-82 to demonstrate the possible use of shake-up processes to identify the charge transfer between the metal ion and the carbon cage. It is found that the exciton binding energy of all systems under investigation is around 0.5 eV.
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| 25. |
- Gao, Bin, et al.
(författare)
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An efficient first-principle approach for electronic structures calculations of nanomaterials
- 2008
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Ingår i: Journal of Computational Chemistry. - : Wiley. - 0192-8651 .- 1096-987X. ; 29:3, s. 434-444
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Tidskriftsartikel (refereegranskat)abstract
- An efficient parallel implementation has been realized for a recently proposed central insertion scheme (Jiang, Liu, Lu, Luo. J Chem Phys 2006,124,214711; J Chem Phys 2006,125, 149902) that allows to calculate electronic structures of nanomaterials at various density functional theory levels. It has adopted the sparse-matrix format for Fock/Kohn-Sham and overlap matrices, as well as a combination of implicitly restarted Arnoldi methods (IRAM) and spectral transformation for computing selected eigenvalues/eigenvectors. A systematic error analysis and control for the proposed method has been provided based on a strict mathematical basis. The efficiency and applicability of the new implementation have been demonstrated by calculations of electronic structures of two different nanomaterials consisting of one hundred thousand electrons.
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| 26. |
- Gao, Bin, et al.
(författare)
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Chirality and diameter dependent x-ray absorption of single walled carbon nanotubes
- 2009
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Ingår i: Journal of Chemical Physics. - : AIP Publishing. - 0021-9606 .- 1089-7690. ; 131:3, s. 034704-1-034704-7
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Tidskriftsartikel (refereegranskat)abstract
- The lack of good understanding on the electronic structure of individual carbon nanotubes severely limited the applications of carbon nanotubes. By employing density functional theory in combination with the equivalent core hole approximation, we are able to provide near edge x-ray absorption fine structure (NEXAFS) spectra of all possible single walled carbon nanotubes (SWCNTs) with diameters below 1.45 nm. It is shown that the pi(*) absorption edges in NEXAFS spectra of SWCNTs are converged already at the length of 3 nm, while a good description of the full spectra can only be obtained after 7 nm. A recent high resolution experimental spectrum of a bundle of SWCNTs with diameters 1.37 +/- 0.08 nm has been successfully assigned by the calculations. Noticeable chirality and diameter dependence have been identified for the simulated NEXAFS spectra. The collection of calculated spectra serves as a useful reference for experimental identification of individual carbon nanotubes.
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| 27. |
- Gao, Bin, et al.
(författare)
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Energy gaps, electronic structures, and x-ray spectroscopies of finite semiconductor single-walled carbon nanotubes
- 2008
-
Ingår i: Journal of Chemical Physics. - : AIP Publishing. - 0021-9606 .- 1089-7690. ; 128:8, s. 084707-1-084707-8
-
Tidskriftsartikel (refereegranskat)abstract
- We report hybrid density functional theory calculations for electronic structures of hydrogen-terminated finite single-walled carbon nanotubes (6,5) and (8,3) up to 100 nm in length. Gap states that are mainly arisen from the hydrogen-terminated edges have been found in (8,3) tubes, but their contributions to the density of states become invisible when the tube is longer than 10 nm. The electronic structures of (6,5) and (8,3) tubes are found to be converged around 20 nm. The calculated band-gap energies of 100 nm long nanotubes are in good agreement with experimental results. The valence band structures of (6,5), (8,3), as well as (5,5) tubes are also investigated by means of ultraviolet photoelectron spectra (UPS), x-ray emission spectroscopy (XES), and the resonant inelastic x-ray scattering (RIXS) spectra theoretically. The UPS, XES and RIXS spectra become converged already at 10 nm. The length-dependent oscillation behavior is found in the RIXS spectra of (5,5) tubes, indicating that the RIXS spectra may be used to determine the size and length of metallic nanotubes. Furthermore, the chiral dependence observed in the simulated RIXS spectra suggests that RIXS spectra could be a useful technique for the determination of chirality of carbon nanotubes.
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| 28. |
- Gao, Bin, 1980-
(författare)
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First Principles Studies of Carbon Based Molecular Materials
- 2008
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The aim of this thesis was to investigate carbon based molecular materials at first principles levels. Special attention has been paid to simulations of X-ray spectroscopies, including near edge X-ray absorption fine structure (NEXAFS), X-ray photoelectron, and X-ray emission spectroscopy, which can provide detailed information about core, occupied and unoccupied molecular orbitals of the systems under investigation. Theoretical calculations have helped to assign fine spectral structures in high resolution NEXAFS spectra of five azabenzenes (pyridine, pyrazine, pyrimidine, pyridazine and s-triazine), and to identify different local chemical environments among them. With the help of NEXAFS, the characters of important chemical bonds that might be responsible for the unique magnetic properties of the tetracyanoethylene compound has been revealed. Calculations have demonstrated that X-ray spectroscopies are powerful tools for isomer identification and structure determination of fullerenes and endohedral metallofullerenes. A joint experimental and theoretical study on metallofullerene Gd@C82 has firmly determined its equilibrium structure, in which the gadolinium atom lies above the hexagon on the C2 axis. It is found that the gadolinium atom could oscillate around its equilibrium position and that its oscillation amplitude increases with increasing temperature. In this thesis, several new computational schemes for large-scale systems have been proposed. Parallel implementation of a central insertion scheme (CIS) has been realized, which allows to effectively calculate electronic structures of very large systems, up to 150,000 electrons, at hybrid density functional theory levels. In comparison with traditional computational methods, CIS provides results with the same high accuracy but requires only a fraction of computational time. One of its applications is to calculate electronic structures of nanodiamond clusters varying from 0.76 nm (29 carbons) to 7.3 nm (20,959 carbons) in diameter, which enabled to resolve the long-standing debate about the validity of the quantum confinement model for nanodiamonds. Electronic structures and X-ray spectroscopies of a series of single-walled carbon nanotubes (SWCNTs) with different diameters and lengths have been calculated, which have made it possible to interpret the existing experimental results.
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| 29. |
- Gao, Bin, et al.
(författare)
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Plasmon resonances in linear noble-metal chains
- 2012
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Ingår i: Journal of Chemical Physics. - : AIP Publishing. - 0021-9606 .- 1089-7690. ; 137:19, s. 194307-
-
Tidskriftsartikel (refereegranskat)abstract
- The electronic excitations of three noble-metall chains-copper, silver, and gold-have been investigated at the time-dependent density functional theory level. The reduced single-electron density matrix is propagated according to the Liouville-von Neumann equation in the real-time domain after an impulse excitation. The propagation in the real-time domain enables us to investigate the formation and size evolution of electronic excitations in these metallic chains with different number of atoms, up to a total of 26 atoms. The longitudinal oscillations at lower excitation energies are dominated by s -> p transitions in these chains and have collective or central resonances, while the first peak involving d -> p transitions in the longitudinal mode appears at a higher excitation energy and shows collective resonances. In the transverse oscillations, there are in most cases d -> p transitions in each resonance, which can be attributed to either central or end resonances. Convergence of the oscillations, in particular those involving the collective and central resonances in the three noble-metal chains can only be observed for chains with 18 atoms or more. Different spectroscopic characteristics among these three metallic chains can be attributed to their different electronic structures, in particular the relativistic effects in the gold chains have a dramatic effect on their electronic structures and excitations.
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| 30. |
- Gao, Bin, et al.
(författare)
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Shape-Dependent Electronic Excitations in Metallic Chains
- 2014
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Ingår i: The Journal of Physical Chemistry C. - : American Chemical Society (ACS). - 1932-7447 .- 1932-7455. ; 118:24, s. 13059-13069
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Tidskriftsartikel (refereegranskat)abstract
- The electronic excitations of silver chains with different geometries (linear, circle, arc and zigzag chains) have been investigated at the time-dependent density functional theory level, by solving the equation of motion of the reduced single-electron density matrix in the real-time domain. A scaling parameter 0 <= lambda <= 1 has been introduced to adjust the two-electron contributions during propagation in the time domain in a way that allows us to distinguish different electronic excitations plasmon and single-particle excitations. The dipole responses, in particular the plasmon resonances of these metallic chains to an external delta-pulse, show a strong dependence on their geometric structures. In most cases, the dipole responses of these chains possess great tunability when altering their geometric parameters the radius of the circle and arc chains, and the bond angle of the zigzag chains. Some excitations in these chains also show a wide tunable excitation energy range, more than 1 eV, making it possible to fine-tune the excitations of the metallic chains at an atomic scale.
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| 31. |
- Gao, Bin, et al.
(författare)
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Simulation of electronic structure of nanomaterials by central insertion scheme
- 2009
-
Ingår i: FRONTIERS OF PHYSICS IN CHINA. - : Springer Science and Business Media LLC. - 1673-3487 .- 1673-3606. ; 4:3, s. 307-314
-
Tidskriftsartikel (refereegranskat)abstract
- An effective central insertion scheme (CIS) that allows to study the electronic structure of nanomaterials at the first principles level is introduced. Taking advantage of advanced numerical methods, such as the implicitly restarted Arnoldi method (IRAM) and spectral transformation, together with efficient parallelization technique, this scheme can provide accurate electronic structures and properties of one-, two-, and three-dimensional nanomaterials with only a fraction of computational time required for conventional quantum chemical calculations. Electronic structures of several nanostructures, such as single-walled carbon nanotubes of sub-100 nm in length, silicon nanoclusters of sub-6.5 nm in diameter and metal doped silicon clusters, calculated at hybrid density functional level are presented.
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| 32. |
- Gao, Bin, et al.
(författare)
-
Spectral identification of fullerene C82 isomers
- 2007
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Ingår i: Journal of Chemical Physics. - : AIP Publishing. - 0021-9606 .- 1089-7690. ; 127:16, s. 164314-1-164314-8
-
Tidskriftsartikel (refereegranskat)abstract
- Ultraviolet photoelectron spectra (UPS) of C-82 isomers have been calculated using hybrid density functional theory in combination with the Gelius model [Proceedings of the International Conference on Electron spectroscopy, edited by D. A. Shirley (North-Holland, Amsterdam, 1972), p. 311; J. Electron Spectrosc. Relat. Phenom. 5, 985 (1974)]. The calculated UPS spectra are found to be isomer dependent and in good agreement with the experimental counterparts. Near-edge x-ray absorption fine structure (NEXAFS), x-ray photoelectron spectroscopy (XPS), x-ray emission spectroscopy, and the resonant inelastic x-ray scattering (RIXS) spectra of three important isomers [3(C-2), 6(C-s), and 9(C-2v)] have also been simulated. Strong isomer dependence has also been found for NEXAFS, XPS, and RIXS spectra.
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| 33. |
- Gao, Bin, et al.
(författare)
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Studies of bromine modified single-walled carbon nanotubes using photoelectron spectroscopy and density-functional theory
- 2006
-
Ingår i: Radiation Physics and Chemistry. - : Elsevier BV. - 0969-806X .- 1879-0895. ; 75:11, s. 1939-1942
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Tidskriftsartikel (refereegranskat)abstract
- Many applications based on single-walled carbon nanotubes (SWNTs) require chemical modification of carbon nanotube to optimize the functionalities of the device. In this contribution we discuss the properties of SWNTs immersed in a hydrobromic acid (HBr) solution. Changes of atomic and electronic structures of bromine modified SWNTs were investigated using photoelectron spectroscopy (PES). Spectra of SWNTs before and after immersion in the HBr solution exhibit different features. To understand the mechanism of interaction between SWNTs and bromine, we performed density-functional theory calculations to reveal the structural changes, adsorption energy and chemical bonding information of SWNTs interacting with bromine. In addition, based on the Gelius model, from the molecular orbitals (MOs), we calculated ultraviolet photoelectron spectra (UPS) of SWNTs with and without functionalizing and compared them with the experiment. The present study is a first step in the understanding of the functionalization mechanism of carbon nanotubes.
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| 34. |
- Hu, Bisong, et al.
(författare)
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Geographical detector-based assessment of multi-level explanatory powers of determinants on China’s medical-service resumption during the COVID-19 epidemic
- 2023
-
Ingår i: Environment and Planning B: Urban Analytics and City Science. - : SAGE. - 2399-8083 .- 2399-8091. ; 50:7, s. 1739-1758
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Tidskriftsartikel (refereegranskat)abstract
- Knowing the multi-level influences of determinants on medical-service resumptions is of great benefits to the policymaking for medical-service recovery at different levels of study units during the post-COVID-19 pandemic era. This article evaluated the hospital- and city-level resumptions of medical services in mainland China based on the data of location-based service (LBS) requests of mobile devices during the two time periods (December 2019 and from February 21 to March 18, 2020). We selected medical-service capacity, human movement, epidemic severity, and socioeconomic factors as the potential determinants on medical-service resumptions and then explicitly assessed their multi-level explanatory powers and the interactive effects of paired determinants using the geographical detector method. The results indicate that various determinants had different individual explanatory powers and interactive relationships/effects at different levels of medical-service resumptions. The current study provides a novel multi-level insight for assessing work resumption and individual/interactive influences of determinants, and considerable implications for regionalized recovery strategies of medical services.
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| 35. |
- Hua, Weijie, et al.
(författare)
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First-Principles Simulation of Soft X-Ray Spectroscopy
- 2012
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Ingår i: Huaxue jinzhan. - 1005-281X. ; 24:6, s. 964-980
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Tidskriftsartikel (refereegranskat)abstract
- Soft x-ray spectroscopy represents a category of instrumental techniques to effectively probe the electronic and chemical structure of molecules, surfaces, and a variety of complexes by core excitations or de-excitations. The basic computational methods, based on the density functional theory, for different absorption and emission processes are reviewed in this paper. Special attention has been paid to the practical implementations and applications of different methods. Details on the simulations of commonly used K-edge x-ray photoelectron, absorption, and emission spectra for a wide range of illustrative examples including molecules, fullerenes, carbon nanotubes, graphenes and DNA, are provided.
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| 36. |
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| 37. |
- Hua, Weijie, et al.
(författare)
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Refinement of DNA Structures through Near-Edge X-ray Absorption Fine Structure Analysis : Applications on Guanine and Cytosine Nucleobases, Nucleosides, and Nucleotides
- 2010
-
Ingår i: Journal of Physical Chemistry B. - : American Chemical Society (ACS). - 1520-6106 .- 1520-5207. ; 114:41, s. 13214-13222
-
Tidskriftsartikel (refereegranskat)abstract
- In this work we highlight the potential of NEXAFS-near-edge X-ray absorption fine structure-analysis to perform refinements of hydrogen-bond structure in DNA. For this purpose we have carried out first-principle calculations of the N1s NEXAFS spectra of the guanine and cytosine nucleobases and their tautomers, nucleosides, and nucleotides in the gas phase, as well as for five crystal structures of guanine, cytosine, or guanosine. The spectra all clearly show imine (pi*(1)) and amine (pi*(2)) nitrogen absorption bands with a characteristic energy difference (Delta). Among all of the intramolecule covalent connections, the tautomerism of hydrogens makes the largest influence, around +/- 0.4-0.5 eV change of Delta, to the spectra due to a switch of single-double bonds. Deoxyribose and ribose sugars can cause at most 0.2 eV narrowing of Delta, while the phosphate groups have nearly negligible effects on the spectra. Two kinds of intermolecule interactions are analyzed, the hydrogen bonds and the stacking effect, by comparing "compressed" and "expanded" models. or by comparing models including or excluding the nearest stacking molecules. The shortening of hydrogen-bond length by 0.2-0.3 angstrom can result in the reduction of Delta by 0.2-0.8 eV. This is because the hydrogen bonds make the electrons more delocalized, and the amine and imine nitrogens become less distinguishable. Moreover, the hydrogen bond has a different ability to influence the spectra of different crystals, with guanine crystals as the largest (change by 0.8 eV) and the guanosine crystal as the smallest (change by 0.2 eV). The stacking has negligible effects on the spectra in all studied systems. A comparison of guanosine to guanine crystals shows that the sugars in the crystal could create "blocks" in the pi-and hydrogen bonds network of bases and thus makes the imine and amine nitrogens More distinguishable with a larger Delta. Our theoretical calculations offer a good match with experimental findings and explain earlier discrepancies in the NEXAFS analysis.
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| 38. |
- Hua, Weijie, et al.
(författare)
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Systematic Study of Soft X-ray Spectra of Poly(Dg)center dot Poly(Dc) and Poly(Da)center dot Poly(Dt) DNA Duplexes
- 2010
-
Ingår i: Journal of Physical Chemistry B. - : American Chemical Society (ACS). - 1520-6106 .- 1520-5207. ; 114:20, s. 7016-7021
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Tidskriftsartikel (refereegranskat)abstract
- In the present work, we have undertaken a combined experimental and theoretical study of X-ray spectroscopies for DNA base pairs, more precisely near-edge X-ray absorption, X-ray emission, and resonant inelastic X-ray scattering applied to poly(dG)center dot poly(dC) and poly(dA)center dot poly(dT) DNA duplexes. We have derived several conclusions on the nature of these X-ray spectra: the stacking of pairs has very little influence on the spectra; the spectra of a DNA composed of mixed Watson-Crick base pairs are well reproduced by linear combinations of GC and AT base pairs involved; the amine and imine nitrogens show noticeable differences as building blocks in the absorption, emission, and resonant emission spectra. The calculated spectra are in good agreement with experimental results. The ramifications of these conclusions for the use of X-ray spectroscopy for DNA are discussed.
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| 39. |
- Hua, Weijie, et al.
(författare)
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X-ray absorption spectra of graphene from first-principles simulations
- 2010
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Ingår i: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 82:15, s. 155433-
-
Tidskriftsartikel (refereegranskat)abstract
- Near edge x-ray absorption fine-structure spectra of graphenes are calculated using hybrid density-functional theory with the equivalent core hole approximation, aiming to resolve the ongoing debate on the interpretation of corresponding experimental spectra. Effects of size, stacking, edges, and defects on the spectra have been analyzed in detail for both C 1s-pi* and C 1s-sigma* transitions. The infinite graphene sheet has been modeled by graphene nanoribbons of different size. The size dependence and convergence of the spectra have been revealed. It is found that the pi-pi interaction between layers have mainly effects on the C 1s-pi* transitions in two different energy regions. The stacking effect smears out the double-peaks structure of the first main pi* peak around 285 eV and results in blueshift of the second pi* structure by almost 2 eV. The calculations show that the pi spectrum of hydrogen saturated edge carbons is redshifted with respect to the central ones and that a new weak sigma* peak around 288 eV appears. The presence of defects can also introduce new spectral features in both pi and sigma regions.
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| 40. |
- Hua, Weijie, et al.
(författare)
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X-ray spectroscopy of blocked alanine in water solution from supermolecular and supermolecular-continuum solvation models : a first-principles study
- 2012
-
Ingår i: Physical Chemistry, Chemical Physics - PCCP. - : Royal Society of Chemistry (RSC). - 1463-9076 .- 1463-9084. ; 14:27, s. 9666-9675
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Tidskriftsartikel (refereegranskat)abstract
- The N1s near-edge X-ray absorption fine structure (NEXAFS) and X-ray emission spectra (XES) of blocked alanine in water solution have been investigated at the first-principles level based on cluster models constructed from classical molecular dynamics simulations. The bulk solvent has been described by both supermolecular and combined supermolecular-continuum models. With the former model we show that NEXAFS spectra convergent with respect to system size require at least the inclusion of the second solvation shell and that averaged spectra over several hundreds of snapshots can well represent the statistical effect of different instantaneous configurations of the solvation shells. With the combined model we demonstrate that calculations of a medium-sized peptide-water supermolecule qualitatively predict the NEXAFS spectrum of the solvated peptide even considering a single geometry. Furthermore, sampling over hundreds of snapshots by the combined model, the explicit inclusion of even a few waters yields an averaged spectrum in good quantitative agreement with the discrete model results. In comparison, the XES spectra show little dependence on the structures
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| 41. |
- Jackson, Sarah S., et al.
(författare)
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Anthropometric Risk Factors for Cancers of the Biliary Tract in the Biliary Tract Cancers Pooling Project
- 2019
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Ingår i: Cancer Research. - : AMER ASSOC CANCER RESEARCH. - 0008-5472 .- 1538-7445. ; 79:15, s. 3973-3982
-
Tidskriftsartikel (refereegranskat)abstract
- Biliary tract cancers are rare but highly fatal with poorly understood etiology. Identifying potentially modifiable risk factors for these cancers is essential for prevention. Here we estimated the relationship between adiposity and cancer across the biliary tract, including cancers of the gallbladder (GBC), intrahepatic bile ducts (IHBDC), extrahepatic bile ducts (EHBDC), and the ampulla of Vater (AVC). We pooled data from 27 prospective cohorts with over 2.7 million adults. Adiposity was measured using baseline body mass index (BMI), waist circumference, hip circumference, waist-to-hip, and waist-to-height ratios. HRs and 95% confidence intervals (95% CI) were estimated using Cox proportional hazards models adjusted for sex, education, race, smoking, and alcohol consumption with age as the time metric and the baseline hazard stratified by study. During 37,883,648 person-years of follow-up, 1,343 GBC cases, 1,194 EHBDC cases, 784 IHBDC cases, and 623 AVC cases occurred. For each 5 kg/m(2) increase in BMI, there were risk increases for GBC (HR = 1.27; 95% CI, 1.19-1.36), IHBDC (HR = 1.32; 95% CI, 1.21-1.45), and EHBDC (HR = 1.13; 95% CI, 1.03-1.23), but not AVC (HR = 0.99; 95% CI, 0.88-1.11). Increasing waist circumference, hip circumference, waist-to-hip ratio, and waist-to-height ratio were associated with GBC and IHBDC but not EHBDC or AVC. These results indicate that adult adiposity is associated with an increased risk of biliary tract cancer, particularly GBC and IHBDC. Moreover, they provide evidence for recommending weight maintenance programs to reduce the risk of developing these cancers. Significance: These findings identify a correlation between adiposity and biliary tract cancers, indicating that weight management programs may help minimize the risk of these diseases.
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| 42. |
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| 43. |
- Jiang, Jingting, et al.
(författare)
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Increased plasma apoM levels in the patients suffered from hepatocellular carcinoma and other chronic liver diseases
- 2008
-
Ingår i: Lipids in Health and Disease. - 1476-511X. ; 7
-
Tidskriftsartikel (refereegranskat)abstract
- Objective: To determine plasma apolipoprotein M ( apoM) levels and other lipid profiles in hepatocellular carcinoma ( HCC) patients compared to other chronic liver diseases and normal subjects. Materials and methods: 36 HCC, 68 chronic hepatitis, 29 liver cirrhosis patients and 64 normal controls were subjected in the present study. Serum lipids, lipoproteins, apolipoprotein AI ( apoAI) and apoB were determined by the conventional methods. Plasma apoM levels were semiquantitatively determined by both dot- blotting and western blotting analysis. Results: Serum levels of triglycerides ( TG), HDL- cholesterol, apoAI and lipoprotein ( a) ( Lp( a)) were significantly lower in the HCC patients than in the normal subjects, whereas there were no obvious differences on serum total cholesterol, LDL- cholesterol and apoB between HCC patients and normal subjects. However, plasma apoM levels in HCC patients were significantly increased than those in the normal subjects, but lower than those in the chronic hepatitis and cirrhosis patients. Conclusion: It is concluded that serum TG, apoAI, HDL- C and Lp( a) were significantly decreased in HCC patients than in controls, whereas plasma apoM levels were significantly increased in the HCC patients. Decreased serum TG, apoAI, HDL- C and Lp( a) may reflect the liver damage in HCC patients, whereas the clinical significance of increased plasma apoM levels in relation to HCC is not clear.
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| 44. |
- Jiang, Jun, et al.
(författare)
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Structure dependent quantum confinement effect in hydrogen-terminated nanodiamond clusters
- 2010
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Ingår i: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 108:9, s. 094303-
-
Tidskriftsartikel (refereegranskat)abstract
- Size-dependent quantum confinement effect on electronic structure of hydrogen-terminated carbon nanodiamond (ND) cluster has been investigated at the hybrid density functional theory level. Large scale all-electron calculations have been carried out for ND clusters of 0.76 nm (29 carbons) to 7.3 nm (20 959 carbons) in diameter. It is demonstrated that the quantum confinement effect in these clusters shows strong structural dependence. An important structural factor, describing the ratio between the number of atoms within the inner core and outer shell of the cluster, is identified which dictates the size-dependent behavior of the electronic states. For ND clusters with diameter smaller than 1.5 nm, the core-shell ratio changes fast with the increase in cluster size, and the evolution of electronic properties does not follow conventional quantum confinement models. For ND clusters exceeding the threshold of 1.5 nm in diameter, the change in the core-shell ratio saturates and quantum confinement effect becomes visible. Electronic states within the inner core and surface show different size dependence, but a general formula is proposed and describes their structure dependent quantum confinement effects. This formula provides useful insights into quantum confinement behavior in ND clusters, and thereby leads to important physical property information. The calculated electron effective masses for core and surface states of ND clusters are in very good agreement with the experiments.
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| 45. |
- Jiang, Ziyu, et al.
(författare)
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HLA class I genes modulate disease risk and age at onset together with DR-DQ in Chinese patients with insulin-requiring type 1 diabetes
- 2021
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Ingår i: Diabetologia. - : Springer Science and Business Media LLC. - 0012-186X .- 1432-0428. ; 64:9, s. 2026-2036
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Tidskriftsartikel (refereegranskat)abstract
- Aims/hypothesis: The study aimed to investigate the effects of HLA class I genes on susceptibility to type 1 diabetes with different onset ages, in addition to the well-established effects of HLA class II genes. Methods: A total of 361 patients with type 1 diabetes (192 patients with onset <18 years and 169 patients with onset ≥18 years) and 500 healthy control participants from China were enrolled and genotyped for the HLA-A, -B, -C, -DQA1, -DQB1 and -DRB1 genes using next-generation sequencing. Results: The susceptible DR3 (β = −0.09, p = 0.0009) and DR4-DQ8 (β = −0.13, p = 0.0059) haplotypes were negatively associated with onset age, while the protective DR11 (β = 0.21, p = 0.0314) and DR12 (β = 0.27, p < 0.0001) haplotypes were positively associated with onset age. After adjustment for linkage disequilibrium with DR-DQ haplotypes, A*11:01:01 was positively associated with onset age (β = 0.06, p = 0.0370), while the susceptible C*15:02:01 was negatively associated with onset age (β = −0.21, p = 0.0050). The unit for β was double square-root (fourth root) transformed years of change in onset age associated with per copy of the HLA haplotype/allele. In addition, B*46:01:01 was protective (OR 0.41, 0.46; pc [corrected for multiple comparisons] = 0.0044, 0.0040), whereas A*24:02:01 (OR 2.71, 2.25; pc = 0.0003, 0.0002) and B*54:01:01 (OR 3.96, 3.79; pc = 0.0018, 0.0004) were predisposing in both the <18 group and the ≥18 group compared with healthy control participants. In the context of DR4-DQ4, A*11:01:01 (61.29% vs 28.26%, pc = 0.0144) was increased while the predisposing A*24:02:01 (19.35% vs 47.83%, pc = 0.0403) was decreased in patients with onset ≥18 years when compared with patients with onset <18 years. Conclusions/interpretation: In addition to DR-DQ haplotypes, novel HLA class I alleles were detected to play a role in susceptibility to type 1 diabetes with different onset ages, which could improve the understanding of disease heterogeneity and has implications for the design of future studies. Graphical abstract: [Figure not available: see fulltext.].
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| 46. |
- Johansson, Mattias, et al.
(författare)
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The influence of obesity-related factors in the etiology of renal cell carcinoma—A mendelian randomization study
- 2019
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Ingår i: PLoS Medicine. - : Public Library of Science (PLoS). - 1549-1277 .- 1549-1676. ; 16:1
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Tidskriftsartikel (refereegranskat)abstract
- Background: Several obesity-related factors have been associated with renal cell carcinoma (RCC), but it is unclear which individual factors directly influence risk. We addressed this question using genetic markers as proxies for putative risk factors and evaluated their relation to RCC risk in a mendelian randomization (MR) framework. This methodology limits bias due to confounding and is not affected by reverse causation.Methods and findings: Genetic markers associated with obesity measures, blood pressure, lipids, type 2 diabetes, insulin, and glucose were initially identified as instrumental variables, and their association with RCC risk was subsequently evaluated in a genome-wide association study (GWAS) of 10,784 RCC patients and 20,406 control participants in a 2-sample MR framework. The effect on RCC risk was estimated by calculating odds ratios (ORSD) for a standard deviation (SD) increment in each risk factor. The MR analysis indicated that higher body mass index increases the risk of RCC (ORSD: 1.56, 95% confidence interval [CI] 1.44–1.70), with comparable results for waist-to-hip ratio (ORSD: 1.63, 95% CI 1.40–1.90) and body fat percentage (ORSD: 1.66, 95% CI 1.44–1.90). This analysis further indicated that higher fasting insulin (ORSD: 1.82, 95% CI 1.30–2.55) and diastolic blood pressure (DBP; ORSD: 1.28, 95% CI 1.11–1.47), but not systolic blood pressure (ORSD: 0.98, 95% CI 0.84–1.14), increase the risk for RCC. No association with RCC risk was seen for lipids, overall type 2 diabetes, or fasting glucose.Conclusions: This study provides novel evidence for an etiological role of insulin in RCC, as well as confirmatory evidence that obesity and DBP influence RCC risk.
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| 47. |
- Laskar, Ruhina S, et al.
(författare)
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Sex specific associations in genome wide association analysis of renal cell carcinoma.
- 2019
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Ingår i: European Journal of Human Genetics. - : Springer Science and Business Media LLC. - 1018-4813 .- 1476-5438. ; 27:10, s. 1589-1598
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Tidskriftsartikel (refereegranskat)abstract
- Renal cell carcinoma (RCC) has an undisputed genetic component and a stable 2:1 male to female sex ratio in its incidence across populations, suggesting possible sexual dimorphism in its genetic susceptibility. We conducted the first sex-specific genome-wide association analysis of RCC for men (3227 cases, 4916 controls) and women (1992 cases, 3095 controls) of European ancestry from two RCC genome-wide scans and replicated the top findings using an additional series of men (2261 cases, 5852 controls) and women (1399 cases, 1575 controls) from two independent cohorts of European origin. Our study confirmed sex-specific associations for two known RCC risk loci at 14q24.2 (DPF3) and 2p21(EPAS1). We also identified two additional suggestive male-specific loci at 6q24.3 (SAMD5, male odds ratio (ORmale) = 0.83 [95% CI = 0.78-0.89], Pmale = 1.71 × 10-8 compared with female odds ratio (ORfemale) = 0.98 [95% CI = 0.90-1.07], Pfemale = 0.68) and 12q23.3 (intergenic, ORmale = 0.75 [95% CI = 0.68-0.83], Pmale = 1.59 × 10-8 compared with ORfemale = 0.93 [95% CI = 0.82-1.06], Pfemale = 0.21) that attained genome-wide significance in the joint meta-analysis. Herein, we provide evidence of sex-specific associations in RCC genetic susceptibility and advocate the necessity of larger genetic and genomic studies to unravel the endogenous causes of sex bias in sexually dimorphic traits and diseases like RCC.
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| 48. |
- Li, Chun-Mei, et al.
(författare)
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First-principles investigation of the composition dependent properties of Ni2+xMn1-xGa shape-memory alloys
- 2010
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Ingår i: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 82:2, s. 024201-1-024201-9
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Tidskriftsartikel (refereegranskat)abstract
- The composition dependent lattice parameter, phase stability, elastic moduli, and magnetic transition temperature of the Ni2+xMn1-xGa shape-memory alloys are studied by using the first-principles exact muffin-tin orbital method in combination with the coherent potential approximation. The lattice parameter and tetragonal shear modulus of the cubic L-21 austenite phase decreases linearly with increasing concentration x of excess Ni atoms. The heats of formation of both cubic L-21 and tetragonal beta''' phases and their difference increase with x, indicating decreasing stability of the cubic and tetragonal phases and increasing driving force for the L-21 to beta''' martensitic transition. Investigating the electronic density of states, we find that the Ni-induced decreasing phase stability can mainly be ascribed to the weakening of the covalent bonding between minority spin states of Ni and Ga. Using the computed parameters, the composition dependence of the martensitic transition temperature is discussed. The theoretical Curie temperature, estimated from the Heisenberg model in combination with the mean-field approximation, is larger for the beta''' phase than for the L-21 phase. For both phases, the Curie temperature decreases nearly linearly with increasing x.
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| 49. |
- Li, Chun-Mei, et al.
(författare)
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Role of magnetic and atomic ordering in the martensitic transformation of Ni-Mn-In from a first-principles study
- 2012
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Ingår i: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 86:21, s. 214205-
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Tidskriftsartikel (refereegranskat)abstract
- The composition-dependent lattice parameters, crystal structure, elastic properties, magnetic moment, and electronic structure of Ni2Mn1+xIn1-x (0 <= x <= 0.6) are studied by using first-principles calculations. It is shown that the martensitic phase transition (MPT) from cubic L2(1) to tetragonal L1(0) accompanies theMn(Mn)-Mn-In ferromagnetic (FM) to antiferromagnetic (AFM) transition, at around the critical composition x = 0.32, in agreement with the experimental measurement. The Mn-In atomic disorder leads to decreasing stability of the martensite relative to the austenite, which depresses the MPT. The shear elastic constant C' of the parent phase first decreases slightly with increasing x and then remains almost unchanged above x = 0.32, indicating C' alone cannot account for the increase of the MPT temperature with x. The total magnetic moments for the L2(1) phase are in good agreement with those determined by experiments, whereas for the L1(0) phase they are slightly larger than the experimental data due to the possibleMn-In atomic disorder in the sample. The calculated density of states demonstrate that the covalent bonding between the minority spin states of Ni and In plays an important role in both the magnetic and structural stability.
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| 50. |
- Li, Chun-Mei, et al.
(författare)
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Site preference and elastic properties of Fe-, Co-, and Cu- doped Ni(2)MnGa shape memory alloys from first principles
- 2011
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Ingår i: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 84:2, s. 024206-
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Tidskriftsartikel (refereegranskat)abstract
- The site preference and elastic properties of Fe-, Co-, and Cu-doped Ni(2)MnGa alloys are investigated by using the first-principles exact muffin-tin orbital method in combination with coherent-potential approximation. It is shown that Fe atom prefers to occupy the Mn and Ni sublattices even in Ga-deficient alloys; Co has strong tendency to occupy the Ni sublattice in all types of alloys; Cu atoms always occupy the sublattice of the host elements in deficiency. For most of the alloys with stable site occupations, both the electron density n and the shear modulus C' can be considered as predictors of the composition dependence of the martensitic transition temperature T(M) of the alloys. The physics underlying the composition-dependent C' are discussed based on the calculated density of states.
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