512 research outputs found
Novel nanorod precipitate formation in neodymium and titanium codoped bismuth ferrite
The discovery of unusual nanorod precipitates in bismuth ferrite doped with Nd and Ti is reported. The atomic structure and chemistry of the nanorods are determined using a combination of high angle annular dark field imaging, electron energy loss spectroscopy, and density functional calculations. It is found that the structure of the BiFeO3 matrix is strongly modified adjacent to the precipitates; the readiness of BiFeO3 to adopt different structural allotropes in turn explains why such a large axial ratio, uncommon in precipitates, is stabilized. In addition, a correlation is found between the alignment of the rods and the orientation of ferroelastic domains in the matrix, which is consistent with the system's attempt to minimize its internal strain. Density functional calculations indicate a finite density of electronic states at the Fermi energy within the rods, suggesting enhanced electrical conductivity along the rod axes, and motivating future investigations of nanorod functionalities
Disordered materials for high-performance lithium-ion batteries: A review
Disordered materials (DMs) have become promising materials in the advancement of lithium-ion batteries (LIBs). Their disordered, open structure is conductive to facilitate efficiency lithium-ion storage. DMs with tunable compositions also possess abundant defects that can interact with Li+, further enhancing their electrochemical performances in LIBs. Yet, revealing the structural origin of the superior electrochemical properties of DM-based LIBs remains a challenge. In this article, we review recent advances in the development of DM-based components for LIBs, such as anodes, cathodes, coating layers, and solid-state electrolytes. We give an overview on the primary methods utilized in preparing and characterizing DMs, while also describing the mechanisms involved in DM synthesis. This review article also addresses the correlation between the structural properties of DMs and their electrochemical performances. Moreover, we elucidate the challenges and future perspectives in the advancement of DM-based LIBs. We outline the key advantages of DMs in enhancing LIB performance over their crystalline counterparts, providing insights for developing superior LIBs through tailored DM development.</p
Migration paths saturations in meta-epidemic systems
In this paper we consider a simple two-patch model in which a population
affected by a disease can freely move. We assume that the capacity of the
interconnected paths is limited, and thereby influencing the migration rates.
Possible habitat disruptions due to human activities or natural events are
accounted for. The demographic assumptions prevent the ecosystem to be wiped
out, and the disease remains endemic in both populated patches at a stable
equilibrium, but possibly also with an oscillatory behavior in the case of
unidirectional migrations. Interestingly, if infected cannot migrate, it is
possible that one patch becomes disease-free. This fact could be exploited to
keep disease-free at least part of the population
Kinetics of coherent order-disorder transition in
Within a phase field approach which takes the strain-induced elasticity into
account, the kinetics of the coherent order-disorder transition is investigated
for the specific case of alloy. It is shown that a microstructure
with cubic precipitates appears as a transient state during the
decomposition of a homogeneous disordered solid solution into a microstructure
with tetragonal precipitates embedded into a disordered matrix. At
low enough temperature, favored by a weak internal stress, only
precipitates grow in the transient microstructure preceding nucleation of the
precipitates that occurs exclusively at the interface of the solid
solution with the precipitates. Analysis of microstructures at
nanoscopic scale shows a characteristic rod shape for the
precipitates due to the combination of their tetragonal symmetry and their
large internal stress.Comment: 2 postscript figures and 1 JPG pag
Structural Strength and Service Life of the Extrusion Forming Die for Agricultural Engine Piston Heads
Three-tier high-strength prestressed combination concave dies are designed to manifacture highpower corn combine harvester engine piston heads. This design integrates the advantages of traditional casting or hot die forging and warm extrusion. The following key parameters, viz radial dimensions of each mating layer, axial bonding and radial contact interaction, are obtained by theoretical calculation. Nonlinear analysis of the contact interaction was carried out, and the die contact condition was studied at no-load and full-load. Based on the Archard wear theory, thermomechanical bonding was studied in operation of the die. Through numerical simulation of the die wear in each operation cycle, the univariate linear regression equation of the die service life was derived, and the reliability of this equation was verified. The results show that the die contact is both stable and reliable if the radial contact interaction of the inner and outer layers is Ξ΄β= 1.9716 mm and Ξ΄β= 1.3870 mm, respectively. With the nitriding layer thickness of 0.24 mm, the extrusion die service life in the production of piston heads corresponds to 6357 pieces.Π Π°Π·ΡΠ°Π±ΠΎΡΠ°Π½Ρ ΡΡΠ΅Ρ
ΡΡΡΡΡΠ½ΡΠ΅ Π²ΡΡΠΎΠΊΠΎΠΏΡΠΎΡΠ½ΡΠ΅ ΠΏΡΠ΅Π΄Π²Π°ΡΠΈΡΠ΅Π»ΡΠ½ΠΎ-Π½Π°ΠΏΡΡΠΆΠ΅Π½Π½ΡΠ΅ ΠΌΠ½ΠΎΠ³ΠΎΠΌΠ΅ΡΡΠ½ΡΠ΅ Π²ΠΎΠ³Π½ΡΡΡΠ΅ Π³ΠΎΠ»ΠΎΠ²ΠΊΠΈ Π΄Π»Ρ ΠΈΠ·Π³ΠΎΡΠΎΠ²Π»Π΅Π½ΠΈΡ Π΄Π½ΠΈΡ ΠΏΠΎΡΡΠ½Ρ Π΄Π²ΠΈΠ³Π°ΡΠ΅Π»Ρ ΠΌΠΎΡΠ½ΠΎΠ³ΠΎ ΠΊΡΠΊΡΡΡΠ·ΠΎΡΠ±ΠΎΡΠΎΡΠ½ΠΎΠ³ΠΎ ΠΊΠΎΠΌΠ±Π°ΠΉΠ½Π°. ΠΠΎΠ½ΡΡΡΡΠΊΡΠΈΡ ΡΠΎΠ΅Π΄ΠΈΠ½ΡΠ΅Ρ Π² ΡΠ΅Π±Π΅ ΠΏΡΠ΅ΠΈΠΌΡΡΠ΅ΡΡΠ²Π° Π»ΠΈΡΡΡ ΠΈΠ»ΠΈ Π³ΠΎΡΡΡΠ΅ΠΉ ΠΊΠΎΠ²ΠΊΠΈ ΠΈ Π³ΠΎΡΡΡΠ΅ΠΉ ΡΠΊΡΡΡΡΠ·ΠΈΠΈ. Π Π°Π΄ΠΈΠ°Π»ΡΠ½ΡΠ΅ ΡΠ°Π·ΠΌΠ΅ΡΡ ΠΊΠ°ΠΆΠ΄ΠΎΠ³ΠΎ ΡΠΎΠ΅Π΄ΠΈΠ½ΡΠ΅ΠΌΠΎΠ³ΠΎ ΡΠ»ΠΎΡ, ΠΎΡΠ΅Π²ΠΎΠ΅ ΡΡΠ΅ΠΏΠ»Π΅Π½ΠΈΠ΅ ΠΈ ΡΠ°Π΄ΠΈΠ°Π»ΡΠ½ΠΎΠ΅ ΠΊΠΎΠ½ΡΠ°ΠΊΡΠ½ΠΎΠ΅ Π²Π·Π°ΠΈΠΌΠΎΠ΄Π΅ΠΉΡΡΠ²ΠΈΠ΅ ΡΠ°ΡΡΡΠΈΡΠ°Π½Ρ ΡΠ΅ΠΎΡΠ΅ΡΠΈΡΠ΅ΡΠΊΠΈ. ΠΡΠΏΠΎΠ»Π½Π΅Π½ Π½Π΅Π»ΠΈΠ½Π΅ΠΉΠ½ΡΠΉ Π°Π½Π°Π»ΠΈΠ· ΠΊΠΎΠ½ΡΠ°ΠΊΡΠ½ΠΎΠ³ΠΎ Π²Π·Π°ΠΈΠΌΠΎΠ΄Π΅ΠΉΡΡΠ²ΠΈΡ, ΠΈΠ·ΡΡΠ΅Π½Ρ ΡΡΠ»ΠΎΠ²ΠΈΡ ΠΊΠΎΠ½ΡΠ°ΠΊΡΠΈΡΠΎΠ²Π°Π½ΠΈΡ Π² Π³ΠΎΠ»ΠΎΠ²ΠΊΠ΅ ΠΏΡΠΈ Π½ΡΠ»Π΅Π²ΠΎΠΉ ΠΈ ΠΏΠΎΠ»Π½ΠΎΠΉ Π½Π°Π³ΡΡΠ·ΠΊΠ΅. ΠΠ° ΠΎΡΠ½ΠΎΠ²Π°Π½ΠΈΠΈ ΡΠ΅ΠΎΡΠΈΠΈ ΠΈΠ·Π½ΠΎΡΠ° ΠΡΡΠ°ΡΠ΄Π° Π²ΡΠΏΠΎΠ»Π½Π΅Π½Π° ΠΎΡΠ΅Π½ΠΊΠ° ΡΠ΅ΡΠΌΠΎΠΌΠ΅Ρ
Π°Π½ΠΈΡΠ΅ΡΠΊΠΎΠ³ΠΎ ΡΡΠ΅ΠΏΠ»Π΅Π½ΠΈΡ Π² ΠΏΡΠΎΡΠ΅ΡΡΠ΅ ΡΠΊΡΠΏΠ»ΡΠ°ΡΠ°ΡΠΈΠΈ Π³ΠΎΠ»ΠΎΠ²ΠΊΠΈ. ΠΡΡΠ΅ΠΌ ΡΠΈΡΠ»Π΅Π½Π½ΠΎΠ³ΠΎ ΠΌΠΎΠ΄Π΅Π»ΠΈΡΠΎΠ²Π°Π½ΠΈΡ ΠΈΠ·Π½ΠΎΡΠ° Π³ΠΎΠ»ΠΎΠ²ΠΊΠΈ Π² ΠΊΠ°ΠΆΠ΄ΠΎΠΌ ΡΠ°Π±ΠΎΡΠ΅ΠΌ ΡΠΈΠΊΠ»Π΅ ΠΏΠΎΠ»ΡΡΠ΅Π½ΠΎ ΠΎΠ΄Π½ΠΎΠΏΠ°ΡΠ°ΠΌΠ΅ΡΡΠΈΡΠ΅ΡΠΊΠΎΠ΅ ΡΡΠ°Π²Π½Π΅Π½ΠΈΠ΅ Π»ΠΈΠ½Π΅ΠΉΠ½ΠΎΠΉ ΡΠ΅Π³ΡΠ΅ΡΡΠΈΠΈ Π΄Π»Ρ ΡΡΠΎΠΊΠ° Π΅Π΅ ΡΠ»ΡΠΆΠ±Ρ; ΠΏΡΠΎΠ²Π΅ΡΠ΅Π½Π° Π΄ΠΎΡΡΠΎΠ²Π΅ΡΠ½ΠΎΡΡΡ Π΄Π°Π½Π½ΠΎΠ³ΠΎ ΡΡΠ°Π²Π½Π΅Π½ΠΈΡ. ΠΠΎΠΊΠ°Π·Π°Π½ΠΎ, ΡΡΠΎ ΠΊΠΎΠ½ΡΠ°ΠΊΡ Π² Π³ΠΎΠ»ΠΎΠ²ΠΊΠ΅ ΡΡΡΠΎΠΉΡΠΈΠ² ΠΈ Π½Π°Π΄Π΅ΠΆΠ΅Π½, ΠΏΡΠΈ ΡΠ°Π΄ΠΈΠ°Π»ΡΠ½ΠΎΠΌ ΠΊΠΎΠ½ΡΠ°ΠΊΡΠ½ΠΎΠΌ Π²Π·Π°ΠΈΠΌΠΎΠ΄Π΅ΠΉΡΡΠ²ΠΈΠΈ Π²Π½ΡΡΡΠ΅Π½Π½Π΅Π³ΠΎ ΠΈ Π½Π°ΡΡΠΆΠ½ΠΎΠ³ΠΎ ΡΠ»ΠΎΠ΅Π² Ξ΄β= 1.9716 ΠΌΠΌ ΠΈ Ξ΄β= 1.3870 ΠΌΠΌ ΡΠΎΠΎΡΠ²Π΅ΡΡΡΠ²Π΅Π½Π½ΠΎ. ΠΡΠΈ ΡΠΎΠ»ΡΠΈΠ½Π΅ Π½ΠΈΡΡΠΈΠ΄Π½ΠΎΠ³ΠΎ ΡΠ»ΠΎΡ 0,24 ΠΌΠΌ ΡΡΠΎΠΊ ΡΠ»ΡΠΆΠ±Ρ ΡΠΊΡΡΡΡΠ·ΠΈΠΎΠ½Π½ΠΎΠΉ Π³ΠΎΠ»ΠΎΠ²ΠΊΠΈ Π² ΠΏΡΠΎΠΈΠ·Π²ΠΎΠ΄ΡΡΠ²Π΅ Π΄Π½ΠΈΡ ΠΏΠΎΡΡΠ½Ρ ΡΠΎΠΎΡΠ²Π΅ΡΡΡΠ²ΡΠ΅Ρ 6357 ΠΈΠ·Π΄Π΅Π»ΠΈΡΠΌ
Cytogenetic and molecular identification of a new wheat-Thinopyrum intermedium addition line with resistance to powdery mildew
Thinopyrum intermedium, which has many useful traits, is valuable for wheat breeding. A new wheat-Thinopyrum addition line, SN100109, was developed from the progeny of common wheat cultivar Yannong 15 and Th. intermedium. It was resistant to most races of Blumeria graminis f. sp tritici (Bgt), which caused powdery mildew in wheat, and its reactions were different from the reactions of gene Pm40 and Pm43. Genomic in situ hybridization (GISH) and molecular marker analysis were used to identify the genomic composition of SN100109. GISH results showed that SN100109 was a wheat-Th. intermedium disomic addition line containing one pair of J chromosomes, and the resistance gene was located on the alien additional chromosomes of SN100109. And four molecular markers BE425942, BF482714, Xgdm93 and BV679214 which were assigned to homologous group 2, were specific molecular markers of the additional chromosomes. All the results indicated that SN100109 contained one pair of 2J chromosomes. SN100109 can be used as a novel germplasm source for introducing powdery mildew resistance genes to wheat in breeding programs
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Surface structures and surface-atom vibrations determined using photoelectron diffraction
Surface structures of {radical}3 {times} {radical}3 R30{degrees} Cl/Ni(111) and c(2 {times} 2)Cl/Cu(001) were determined using low- temperature angle-resolved photoemission extended fine structure (ARPEFS), which yields both more accurate surface and near-surface structural information for deeper substrate layers. A study of surface-atom vibrations for {radical}3 {times} {radical}3 R30{degrees} Cl/Ni(111) and c(2 {times} 2)Cl/Cu(001) was made using temperature-dependent ARPEFS. A model for predicting the adsorbate vibrational anisotropy from surface structures was proposed and also successfully applied to several adsorbate systems. This model offered a simple and straightforward physical picture for understanding different types of vibrational anisotropy
Increasing incidence of hemorrhagic fever with renal syndrome could be associated with livestock husbandry in Changchun, Northeastern China
Background: Since the end of the 1990s, the incidence of hemorrhagic fever with renal syndrome (HFRS) has been increasing dramatically in Changchun, northeastern China. However, it is unknown which, and how, underlying risk factors have been involved in the reemergence of the disease.Methods: Data on HFRS cases at the county scale were collected from 1998 to 2012. Data on livestock husbandry including the numbers of large animals (cattle, horses, donkeys and mules), sheep, and deer, and on climatic and land cover variables were also collected. Epidemiological features, including the spatial, temporal and human patterns of disease were characterized. The potential factors related to spatial heterogeneity and temporal trends were analyzed using standard and time-series Poisson regression analysis, respectively.Results: Annual incidence varied among the 10 counties. Shuangyang County in southeastern Changchun had the highest number of cases (1,525 cases; 35.9% of all cases), but its population only accounted for 5.6% of the total population. Based on seasonal pattern in HFRS incidence, two epidemic phases were identified. One was a single epidemic peak at the end of each year from 1988 to 1997 and the other consisted of dual epidemic peaks at both the end and the beginning of each year from 1998 to the end of the study period. HFRS incidence was higher in males compared to females, and most of the HFRS cases occurred in peasant populations. The results of the Poisson regression analysis indicated that the spatial distribution and the increasing incidence of HFRS were significantly associated with livestock husbandry and climate factors, particularly with deer cultivation.Conclusions: Our results indicate that the re-emergence of HFRS in Changchun has been accompanied by changing seasonal patterns over the past 25 years. Integrated measures focusing on areas related to local livestock husbandry could be helpful for the prevention and control of HFRS
A phase-field model for phase transformations in glass-forming alloys
A phase-field model is proposed for phase transformations in glass-forming alloys. The glass transition is introduced as a structural relaxation, and the competition between the glass and crystalline phases is investigated. The simulations are performed for Cu-Zr alloys, employing thermodynamic and kinetic parameters derived from reported thermodynamic modeling and molecular dynamics simulation results,[1β3] respectively. Four distinct phase fields are treated with a multi-phase-field approach, representing the liquid/glass, Cu10Zr7, CuZr, and CuZr2 phases. In addition, a continuum-field method is applied to the liquid to accommodate the liquidβglass transformation. The combined phase-field approach is used to investigate the glass formation tendency, and critical cooling rates are estimated and compared with the reported experimental values
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