[Objective] Effects of different contents of calcium oxide on physicochemi- cal properties of spray-dried bayberry powder were studied. [Method] Bayberry pow- der produced from bayberry juice adding 0, 2 and 4 g/L cal...[Objective] Effects of different contents of calcium oxide on physicochemi- cal properties of spray-dried bayberry powder were studied. [Method] Bayberry pow- der produced from bayberry juice adding 0, 2 and 4 g/L calcium oxide using the spray drying technique has been selected. The physicochemical properties of the spray-dried bayberry powder were investigated by determining moisture content, colour, apparent density, wettability, angle of repose and moisture absorption rate of bayberry powder. [Result] The results showed that the content of calcium oxide had a significant effect on the moisture content and colour of bayberry powder. Effects of different contents of calcium oxide on the apparent density of spray-dried bayber- ry powder were not obvious. Adding calcium oxide had a significant effect on the wettability, angle of repose and moisture absorption rate of spray-dried bayberry powder, nevertheless, there was not obvious difference on these properties between adding 2 and 4 g/L calcium oxide. [Conclusion] The results confirmed that the con- tent of calcium oxide had a significant effect on the properties of spray-dried bay- berry powder.展开更多
The microstructure and mechanical properties of A1-4.5wt% Cu Mloy reinforced with different volume fractions （1.5vo1%, 3vo1%, and 5vo1%） of alumina nanoparticles, fabricated using stir casting method, were investiga...The microstructure and mechanical properties of A1-4.5wt% Cu Mloy reinforced with different volume fractions （1.5vo1%, 3vo1%, and 5vo1%） of alumina nanoparticles, fabricated using stir casting method, were investigated. CMculated amounts of alumina nanoparticles （about ~50 nm in size） were ball-milled with aluminum powders in a planetary ball mill for 5 h, and then the packets of milled powders were incorporated into molten Al-4.5wt% Cu alloy. Microstructural studies of the nanocomposites reveal a uniform distribution of alumina nanoparticles in the A1-4.5wt% Cu matrix. The results indicate an outstanding improvement in compression strength and hardness due to the effect of nanoparticle addition. The aging behavior of the composite is also evaluated, indicating that the addition of alumina nanoparticles can accelerate the aging process of the Mloy, resulting in higher peak hardness values.展开更多
TiO2-hydroxyapatite （HA） nanostructured coatings were produced by atmospheric plasma spray method. The effects of starting powder composition and grain size on their mechanical properties were investigated. The micr...TiO2-hydroxyapatite （HA） nanostructured coatings were produced by atmospheric plasma spray method. The effects of starting powder composition and grain size on their mechanical properties were investigated. The microstructure and morphology were characterized by X-ray diffraction and scanning electron microscopy （SEM）. It is found that the coating with 10% HA has the best mechanical properties. Based on Rietveld refinement method, the mean grain size of the as-received powder （212 nm） extensively decreases to 66.4 nm after 20 h of high-energy ball milling. In spite of grain growth, the deposited coatings maintain their nanostructures with the mean grain size of 112 nm. SEM images show that there is a lower porosity in the coating with a higher HA content. Optical microscopy images show that uniform thickness is obtained for all the coatings.展开更多
It is still a challenge to clarify the dependence of overall elastic properties of heterogeneous materials on the microstructures of non-elliposodal inhomogeneities （cracks, pores, foreign particles）. From the theor...It is still a challenge to clarify the dependence of overall elastic properties of heterogeneous materials on the microstructures of non-elliposodal inhomogeneities （cracks, pores, foreign particles）. From the theory of elasticity, the formulation of the perturbance elastic fields, coming from a non-ellipsoidal inhomogeneity embedded in an infinitely extended material with remote constant loading, inevitably involve one or more integral equations. Up to now, due to the mathematical difficulty, there is almost no explicit analytical solution obtained except for the ellipsoidal inhomo- geneity. In this paper, we point out the impossibility to trans- form this inhomogeneity problem into a conventional Eshelby problem by the equivalent inclusion method even if the eigenstrain is chosen to be non-uniform. We also build up an equivalent model, called the second Eshelby problem, to investigate the perturbance stress. It is probably a better template to make use of the profound methods and results of conventional Eshelby problems of non-ellipsoidal inclusions.展开更多
The DNA i-motif is a quadruplex structure formed in tandem cytosine-rich sequences in slightly acidic conditions. Besides being considered as a building block of DNA nano-devices, it may also play potential roles in r...The DNA i-motif is a quadruplex structure formed in tandem cytosine-rich sequences in slightly acidic conditions. Besides being considered as a building block of DNA nano-devices, it may also play potential roles in regulating chromo- some stability and gene transcriptions. The stability of i-motif is crucial for these functions. In this work, we investigated the mechanical stability of a single i-motif formed in the human telomeric sequence 51-（CCCTAA）3CCC, which revealed a novel pH and loading rate-dependent bimodal unfolding force distribution. Although the cause of the bimodal unfolding force species is not clear, we proposed a phenomenological model involving a direct unfolding favored at lower loading rate or higher pH value, which is subject to competition with another unfolding pathway through a mechanically stable inter- mediate state whose nature is yet to be determined. Overall, the unique mechano-chemical responses of i-motif-provide a new perspective to its stability, which may be useful to guide designing new i-motif-based DNA mechanical nano-devices.展开更多
The Wufeng-Longmaxi Formation shales with burial depths > 3 500 m in the southern Sichuan Basin are believed to have large shale gas potentials.However,the reservoir properties and gasin-place(GIP) contents of thes...The Wufeng-Longmaxi Formation shales with burial depths > 3 500 m in the southern Sichuan Basin are believed to have large shale gas potentials.However,the reservoir properties and gasin-place(GIP) contents of these shales exhibit variations across different sublayers.In this study,a set of Wufeng-Longmaxi shales with burial depths of 4 000–4 200 m was derived from the Well Y101H2 in the Luzhou area,and the differences in geological and geochemical characteristics,porosity,water saturation and GIP content of various sublayer shales were investigated.The results indicate that the TOC content and effective porosity of the upper(LMX1-4) and lower(LMX1-3) sublayer shales of the first member of the Longmaxi Formation are better than those of the Wufeng Formation(WF) shales,which results in the LMX1-4 and LMX1-3 shales having higher GIP contents than the WF shales.The GIP contents of the LMX1-3 shales are higher than those of the LMX1-4 shales,and this is likely because the organic matter of the LMX1-3 shales had more aquatic organisms and was preserved in a stronger reductive environment,which leads to a stronger gas generation potential.In contrast to the middle-shallow LMX1-4 shales in the Sichuan Basin,the deep LMX1-4 shales in the Luzhou area have advantageous reservoir properties and GIP contents,and thus it is promising to synchronously exploit the deep LMX1-4 and LMX1-3 shales in some regions of the southern Sichuan Basin.展开更多
This paper investigates the lowest-energy structures, stabilities and electronic properties of （BAs）n clusters （n=1- 14） by means of the density-functional theory. The results show that the lowest-energy structure...This paper investigates the lowest-energy structures, stabilities and electronic properties of （BAs）n clusters （n=1- 14） by means of the density-functional theory. The results show that the lowest-energy structures undergo a structural change from two-dimensional to three-dimensional when n ： 4. With the increase of the cluster size （n=6）, the （BAs）n clusters tend to adopt cage-like structures, which can be considered as being built from B2As2 and six-membered rings with B-As bond alternative arrangement. The binding energy per atom, second-order energy differences, vertical electron affinity and vertical ionization potential are calculated and discussed. The caculated HOMO-LUMO gaps reveal that the clusters have typical semiconductor characteristics. The analysis of partial density of states suggests that there are strong covalence and molecular characteristics in the clusters.展开更多
Exchange coupling between topological insulator and ferromagnetic insulator through proximity effect is strongly attractive for both fundamental physics and technological applications. Here we report a comprehensive i...Exchange coupling between topological insulator and ferromagnetic insulator through proximity effect is strongly attractive for both fundamental physics and technological applications. Here we report a comprehensive investigation on the growth behaviors of prototype topological insulator Bi2Se3 thin film on a single-crystalline LaCoO3 thin film on SrTiO3 substrate, which is a strain-induced ferromagnetic insulator. Different from the growth on other substrates, the Bi2Se3 films with highest quality on LaCoO3 favor a relatively low substrate temperature during growth. As a result, an inverse dependence of carrier mobility with the substrate temperature is found. Moreover, the magnetoresistance and coherence length of weak antilocalization also have a similar inverse dependence with the substrate temperature, as revealed by the magnetotransport measurements. Our experiments elucidate the special behaviors in Bi2Se3/LaCoO3 heterostructures, which provide a good platform for exploring related novel quantum phenomena, and are inspiring for device applications.展开更多
In this paper, we perform the density functional theory （DFT） -based calculations by the first-principles pseudopo- tential method to investigate the physical properties of the newly discovered superconductor LaRu2A...In this paper, we perform the density functional theory （DFT） -based calculations by the first-principles pseudopo- tential method to investigate the physical properties of the newly discovered superconductor LaRu2As2 for the first time. The optimized structural parameters are in good agreement with the experimental results. The calculated independent elas- tic constants ensure the mechanical stability of the compound. The calculated Cauchy pressure, Pugh＇s ratio as well as Poisson＇s ratio indicate that LaRu2As2 should behave as a ductile material. Due to low Debye temperature, LaRu2As2 may be used as a thermal barrier coating （TBC） material. The new compound should exhibit metallic nature as its valence bands overlap considerably with the conduction bands. LaRu2As2 is expected to be a soft material and easily machinable because of its low hardness value of 6.8 GPa. The multi-band nature is observed in the calculated Fermi surface. A highly anisotropic combination of ionic, covalent and metallic interactions is expected to be in accordance with charge density calculation.展开更多
In this study, nano ferrite materials were produced to replace costive industrial materials<span style="font-family:;" "=""> </span><span style="font-family:Verdana;"&...In this study, nano ferrite materials were produced to replace costive industrial materials<span style="font-family:;" "=""> </span><span style="font-family:Verdana;"><span style="font-size:10.0pt;font-family:" color:#943634;"=""><span style="font-family:Verdana;white-space:normal;">[1]</span></span><span style="font-size:10.0pt;font-family:;" "=""></span><span style="font-size:10.0pt;font-family:" times="" new="" roman","serif";"=""><span></span></span></span><span></span><span><span></span></span><span style="font-family:Verdana;">.</span><span style="font-family:;" "=""> </span><span style="font-family:Verdana;">Ferrite nanoparticles are the interesting material due to their rich and unique physical and chemical properties. They find applications in catalysis, bio-processing, medicine, magnetic recording, adsorption, devices etc.</span><span style="font-family:;" "=""> </span><span style="font-family:;" "=""><span style="font-family:Verdana;">Using co-participation method, five nano ferrite samples Zn</span><sub><span style="font-family:Verdana;">0.5</span></sub><span style="font-family:Verdana;">Mg</span><sub><span style="font-family:Verdana;">0.5-x</span></sub><span style="font-family:Verdana;">Li</span><sub><span style="font-family:Verdana;">2x</span></sub><span style="font-family:Verdana;">Fe</span><sub><span style="font-family:Verdana;">2</span></sub><span style="font-family:Verdana;">O</span><sub><span style="font-family:Verdana;">4</span></sub><span style="font-family:Verdana;"> (x = 0.00, 0.10, 0.20, 0.30 and 0.40) were prepared. The electrical and optical properties of the Zn</span><sub><span style="font-family:Verdana;">0.5</span></sub><span style="font-family:Verdana;">Mg</span><sub><span style="font-family:Verdana;">0.5-x</span></sub><span style="font-family:Verdana;">Li</span><sub><span style="font-family:Verdana;">2x</span></sub><span style="font-family:Verdana;">Fe</span><sub><span style="font-family:Verdana;">2</span></sub><span style="font-family:Verdana;">O</span><sub><span style="font-family:Verdana;">4</span></sub><span style="font-family:Verdana;"> samples were studied using the Ultraviolet-visible (UV-Vis) spectroscopy. The results verified that the formation of the absorption coefficient of the five samples of Zn</span><sub><span style="font-family:Verdana;">0.5</span></sub><span style="font-family:Verdana;">Mg</span><sub><span style="font-family:Verdana;">0.5-x</span></sub><span style="font-family:Verdana;">Li</span><sub><span style="font-family:Verdana;">2x</span></sub><span style="font-family:Verdana;">Fe</span><sub><span style="font-family:Verdana;">2</span></sub><span style="font-family:Verdana;">O</span><sub><span style="font-family:Verdana;">4</span></sub><span style="font-family:Verdana;"> increased with the increase of Lithium (Li</span><sub><span style="font-family:Verdana;">2x</span></sub><span style="font-family:Verdana;">). The energy band gap of the Zn</span><sub><span style="font-family:Verdana;">0.5</span></sub><span style="font-family:Verdana;">Mg</span><sub><span style="font-family:Verdana;">0.5-x</span></sub><span style="font-family:Verdana;">Li</span><sub><span style="font-family:Verdana;">2x</span></sub><span style="font-family:Verdana;">Fe</span><sub><span style="font-family:Verdana;">2</span></sub><span style="font-family:Verdana;">O</span><sub><span style="font-family:Verdana;">4</span></sub><span style="font-family:Verdana;"> samples ranged </span></span><span style="font-family:Verdana;">from</span><span style="font-family:Verdana;"> 3.28 to 3.12</span><span style="font-family:;" "=""> </span><span style="font-family:Verdana;">eV</span><span style="font-family:;" "=""> </span><span style="font-family:Verdana;">[1]</span><span style="font-family:;" "=""></span><span style="font-family:" minion="" pro="" capt","serif";"=""><span></span></span><span style="font-family:Verdana;">.</span><span style="font-family:;" "=""> </span><span style="font-family:;" "=""><span style="font-family:Verdana;">The extinction coefficient (K) for five samples of Zn</span><sub><span style="font-family:Verdana;">0.5</span></sub><span style="font-family:Verdana;">Li</span><sub><span style="font-family:Verdana;">2x</span></sub><span style="font-family:Verdana;">Mg</span><sub><span style="font-family:Verdana;">0.5-x</span></sub><span style="font-family:Verdana;">Fe</span><sub><span style="font-family:Verdana;">2</span></sub><span style="font-family:Verdana;">O</span><sub><span style="font-family:Verdana;">4</span></sub><span style="font-family:Verdana;"> increased with the increase of Lithium (Li</span><sub><span style="font-family:Verdana;">2x</span></sub><span style="font-family:Verdana;">) at 338 nm f</span></span><span style="font-family:Verdana;">ro</span><span style="font-family:Verdana;">m 0.074 to 0.207. The high magnitude of optical conductivity is (1.34</span><span style="font-family:;" "=""> </span><span style="font-family:Verdana;">×</span><span style="font-family:;" "=""> </span><span style="font-family:;" "=""><span style="font-family:Verdana;">10</span><sup><span style="font-family:Verdana;">12</span></sup><span style="font-family:Verdana;"> sec<span style="font-size:10px;"><sup>-1</sup></span></span><span style="font-family:Verdana;">) and the maximum value of electrical conductivity is 42</span></span><span style="font-family:;" "=""> </span><span style="font-family:Verdana;">(Ω<sup>.</sup></span><span style="font-family:;" "=""><span><span style="font-family:Verdana;">cm)<span style="font-size:10px;"><sup>-1</sup></span></span><span style="font-family:Verdana;">. This may due to the electrical and optical properties of lithium.</span></span></span>展开更多
On the basis of geological investigating work and experimental studies on slide zone soil of one landslide in Tibet,the authors analyzed granulometric composition,clay mineral composition and physical and mechanical p...On the basis of geological investigating work and experimental studies on slide zone soil of one landslide in Tibet,the authors analyzed granulometric composition,clay mineral composition and physical and mechanical properties for the soil in the slide zone.The soil samples are gravel containing fine particle.Particles larger than 2 mm occupy the main proportion with the content 51.5%--68.5%.The relative content of clay minerals is low.The clay minerals are illite smectite mixed layer and kaolinite,and their relative contents are 6%--13% and 4%-11%,respectively.The main mineral ingredient is quartz and the relative content is over 30%.Therefore,the soil’s hydrophily is poor.The cohesion and internal friction angle are high,causing preferable physical-mechanical features of slide zone soil.On the basis of the obtained data,the landslide stability is evaluated by means of limit equilibrium method.The safety factors are 3.191 and 1.92 respectively under both natural and normal water level conditions.The study results show that the landslide is stable.It can provide the appropriate basis and reference for landslide stability evaluation and landslide control in Tibet.展开更多
In the paper ,we study longtime dynamic behavior of dissipative soliton equation existence of attractor ,geometrical structure of attractor dynamic behavior under the parametric perturbation of dissipative soliton equ...In the paper ,we study longtime dynamic behavior of dissipative soliton equation existence of attractor ,geometrical structure of attractor dynamic behavior under the parametric perturbation of dissipative soliton equation.estimate of fractal dimension of attractor.展开更多
Recent advances in rare-earth-free hard-magnetic materials including magnetic bulk, thin films, nanocomposites and nanostructures are introduced. Since the costs of the rare-earth metals boosts up the price of the hig...Recent advances in rare-earth-free hard-magnetic materials including magnetic bulk, thin films, nanocomposites and nanostructures are introduced. Since the costs of the rare-earth metals boosts up the price of the high-performance rare-earth permanent magnets, there is a much revived interest in various types of hard-magnetic materials based on rare-earth-free compounds. The 3d transition metals and their alloys with large coercivity and high Curie temperatures(working temperatures) are expected to overcome the disadvantages of rare-earth magnets. Making rare-earth-free magnets with a large energy product to meet tomorrow's energy needs is still a challenge.展开更多
A red-emitting heteroleptic cyclometalated platinum（II） complex containing an ancillary ligand of pyra- zol-based diketone derivative was synthesized. Its optophysical and electroluminescent properties were studied....A red-emitting heteroleptic cyclometalated platinum（II） complex containing an ancillary ligand of pyra- zol-based diketone derivative was synthesized. Its optophysical and electroluminescent properties were studied. Compared to the reported （piq）Pt（acac） complex, this platinum（II） complex exhibited a blue-shifted UV absorption band at 300--450 nm, a low LUMO energy level and improved electroluminescent property. Using this platinum（II） complex as a single doping emitter and a blend of ploy（9,9-dioctylfluorene） and 2-tert-butylphenyl-5-phenyl- 1,3,4-oxadiazole as a host matrix, the fabricated polymer light-emitting devices displayed saturated red emission with a peak at 648 um and a shoulder at 601 nm. Furthermore, the emission quenching of the platinum（II） complex was significantly suppressed in these devices at high current density due to an introduction of the non-planar pyra- zol group into the ancillary ligand.展开更多
metry data. The free energy change for charge separation （AGcs） was estimated to be exothermic with --0.51 eV, which favored the formation of charge-separation state. The PET from ZnPc to C60 in ZnPc-C60 made the dy...metry data. The free energy change for charge separation （AGcs） was estimated to be exothermic with --0.51 eV, which favored the formation of charge-separation state. The PET from ZnPc to C60 in ZnPc-C60 made the dyad exhibit stronger reverse saturable absorption performance compared with C60 and the control sample in the Z-scan experiments, which indicated the synergistic effect of two active moieties in the dyad.展开更多
A Nd-doped GdNbO4 single crystals have been grown successfully using the Czochralski technique. The chemical etching method was employed to study the defects in the structural morphology of Nd：GdNbO4 crystal with pho...A Nd-doped GdNbO4 single crystals have been grown successfully using the Czochralski technique. The chemical etching method was employed to study the defects in the structural morphology of Nd：GdNbO4 crystal with phosphoric acid etchant. Mechanical proper- ties （such as hardness, yield strength, fracture toughness, and brittle index） of the as-grown crystal were system- atically estimated on the basis of the Vickers hardness test for the first time. The transmission spectrum of Nd： GdNbO4 was measured in the wavelength range of 320- 2400 nm at room temperature, and the absorption peaks were assigned. Results hold great significance for further research on Nd：GdNbO4.展开更多
An elaborated theoretical investigation on the optical and electronic properties of three fluorene-based plati- num（II） and iridium（III） cyclometalated complexes Pt-a, Ir-a and lr-b is reported. The geometric and ...An elaborated theoretical investigation on the optical and electronic properties of three fluorene-based plati- num（II） and iridium（III） cyclometalated complexes Pt-a, Ir-a and lr-b is reported. The geometric and electronic structures of the complexes in the ground state are studied with density functional theory and Hartree Fock ap- proaches, while the lowest triplet excited states are optimized by singles configuration interaction （CIS） methods. At the time-dependent density functional theory （TD-DFT） level, molecular absorption and emission properties were calculated on the basis of optimized ground- and excited-state geometries, respectively. The computational results show that the appearance of triphenylamino （TPA） moiety at the 9-position of fluorene ring favors the hole-creation and leads to red-shifts of absorption and emission spectra. Moreover, Pt-a and Ir-b are nice hole-transporting materials whereas Ir-a has good charge-transfer balance, which render them useful for the realiza- tion of efficient OLEDs （Organic Light-Emitting Diodes）.展开更多
Based on the range space property （RSP）, the equivalent conditions between nonnegative solutions to the partial sparse and the corresponding weighted l1-norm minimization problem are studied in this paper. Different...Based on the range space property （RSP）, the equivalent conditions between nonnegative solutions to the partial sparse and the corresponding weighted l1-norm minimization problem are studied in this paper. Different from other conditions based on the spark property, the mutual coherence, the null space property （NSP） and the restricted isometry property （RIP）, the RSP- based conditions are easier to be verified. Moreover, the proposed conditions guarantee not only the strong equivalence, but also the equivalence between the two problems. First, according to the foundation of the strict complemenrarity theorem of linear programming, a sufficient and necessary condition, satisfying the RSP of the sensing matrix and the full column rank property of the corresponding sub-matrix, is presented for the unique nonnegative solution to the weighted l1-norm minimization problem. Then, based on this condition, the equivalence conditions between the two problems are proposed. Finally, this paper shows that the matrix with the RSP of order k can guarantee the strong equivalence of the two problems.展开更多
基金Supported by the Project of Natural Science Fund of Zhejiang Province(Y3110376)~~
文摘[Objective] Effects of different contents of calcium oxide on physicochemi- cal properties of spray-dried bayberry powder were studied. [Method] Bayberry pow- der produced from bayberry juice adding 0, 2 and 4 g/L calcium oxide using the spray drying technique has been selected. The physicochemical properties of the spray-dried bayberry powder were investigated by determining moisture content, colour, apparent density, wettability, angle of repose and moisture absorption rate of bayberry powder. [Result] The results showed that the content of calcium oxide had a significant effect on the moisture content and colour of bayberry powder. Effects of different contents of calcium oxide on the apparent density of spray-dried bayber- ry powder were not obvious. Adding calcium oxide had a significant effect on the wettability, angle of repose and moisture absorption rate of spray-dried bayberry powder, nevertheless, there was not obvious difference on these properties between adding 2 and 4 g/L calcium oxide. [Conclusion] The results confirmed that the con- tent of calcium oxide had a significant effect on the properties of spray-dried bay- berry powder.
文摘The microstructure and mechanical properties of A1-4.5wt% Cu Mloy reinforced with different volume fractions （1.5vo1%, 3vo1%, and 5vo1%） of alumina nanoparticles, fabricated using stir casting method, were investigated. CMculated amounts of alumina nanoparticles （about ~50 nm in size） were ball-milled with aluminum powders in a planetary ball mill for 5 h, and then the packets of milled powders were incorporated into molten Al-4.5wt% Cu alloy. Microstructural studies of the nanocomposites reveal a uniform distribution of alumina nanoparticles in the A1-4.5wt% Cu matrix. The results indicate an outstanding improvement in compression strength and hardness due to the effect of nanoparticle addition. The aging behavior of the composite is also evaluated, indicating that the addition of alumina nanoparticles can accelerate the aging process of the Mloy, resulting in higher peak hardness values.
文摘TiO2-hydroxyapatite （HA） nanostructured coatings were produced by atmospheric plasma spray method. The effects of starting powder composition and grain size on their mechanical properties were investigated. The microstructure and morphology were characterized by X-ray diffraction and scanning electron microscopy （SEM）. It is found that the coating with 10% HA has the best mechanical properties. Based on Rietveld refinement method, the mean grain size of the as-received powder （212 nm） extensively decreases to 66.4 nm after 20 h of high-energy ball milling. In spite of grain growth, the deposited coatings maintain their nanostructures with the mean grain size of 112 nm. SEM images show that there is a lower porosity in the coating with a higher HA content. Optical microscopy images show that uniform thickness is obtained for all the coatings.
基金supported by the National Natural Science Foundation of China (10872086 and 11072105)
文摘It is still a challenge to clarify the dependence of overall elastic properties of heterogeneous materials on the microstructures of non-elliposodal inhomogeneities （cracks, pores, foreign particles）. From the theory of elasticity, the formulation of the perturbance elastic fields, coming from a non-ellipsoidal inhomogeneity embedded in an infinitely extended material with remote constant loading, inevitably involve one or more integral equations. Up to now, due to the mathematical difficulty, there is almost no explicit analytical solution obtained except for the ellipsoidal inhomo- geneity. In this paper, we point out the impossibility to trans- form this inhomogeneity problem into a conventional Eshelby problem by the equivalent inclusion method even if the eigenstrain is chosen to be non-uniform. We also build up an equivalent model, called the second Eshelby problem, to investigate the perturbance stress. It is probably a better template to make use of the profound methods and results of conventional Eshelby problems of non-ellipsoidal inclusions.
基金supported by Grants from the National Research Foundation through the Mechanobiology Institute Singapore and the Ministry of Education of Singapore(Grant No.MOE2012-T3-1-001)[to Yan J]the National Basic Research Program of China(Grant No.2013CB932800)+1 种基金the Major Research Plan of the National Natural Science Foundation of China(Grant Nos.91027046 and 91027045)the Fundamental Research Funds for the Central Universities(Grant No.2013121005)
文摘The DNA i-motif is a quadruplex structure formed in tandem cytosine-rich sequences in slightly acidic conditions. Besides being considered as a building block of DNA nano-devices, it may also play potential roles in regulating chromo- some stability and gene transcriptions. The stability of i-motif is crucial for these functions. In this work, we investigated the mechanical stability of a single i-motif formed in the human telomeric sequence 51-（CCCTAA）3CCC, which revealed a novel pH and loading rate-dependent bimodal unfolding force distribution. Although the cause of the bimodal unfolding force species is not clear, we proposed a phenomenological model involving a direct unfolding favored at lower loading rate or higher pH value, which is subject to competition with another unfolding pathway through a mechanically stable inter- mediate state whose nature is yet to be determined. Overall, the unique mechano-chemical responses of i-motif-provide a new perspective to its stability, which may be useful to guide designing new i-motif-based DNA mechanical nano-devices.
基金supported by the National Natural Science Foundation of China (Nos.41925014,42173031)the Natural Science Foundation of Guangdong Province (No.2021A1515011381)the Project of PetroChina Southwest Oil and Gas Fields (No.XNS-YYY-JS2021-49)。
文摘The Wufeng-Longmaxi Formation shales with burial depths > 3 500 m in the southern Sichuan Basin are believed to have large shale gas potentials.However,the reservoir properties and gasin-place(GIP) contents of these shales exhibit variations across different sublayers.In this study,a set of Wufeng-Longmaxi shales with burial depths of 4 000–4 200 m was derived from the Well Y101H2 in the Luzhou area,and the differences in geological and geochemical characteristics,porosity,water saturation and GIP content of various sublayer shales were investigated.The results indicate that the TOC content and effective porosity of the upper(LMX1-4) and lower(LMX1-3) sublayer shales of the first member of the Longmaxi Formation are better than those of the Wufeng Formation(WF) shales,which results in the LMX1-4 and LMX1-3 shales having higher GIP contents than the WF shales.The GIP contents of the LMX1-3 shales are higher than those of the LMX1-4 shales,and this is likely because the organic matter of the LMX1-3 shales had more aquatic organisms and was preserved in a stronger reductive environment,which leads to a stronger gas generation potential.In contrast to the middle-shallow LMX1-4 shales in the Sichuan Basin,the deep LMX1-4 shales in the Luzhou area have advantageous reservoir properties and GIP contents,and thus it is promising to synchronously exploit the deep LMX1-4 and LMX1-3 shales in some regions of the southern Sichuan Basin.
基金supported by the National Natural Science Foundation of China (Grant No. 10964012)the Priority Subject Program for Theoretical Physics of Xinjiang Normal University and the Fund of the Education Department of Xinjiang Uygur Autonomous Region of China (Grant No. xjedu2009i27)the Science and Technology Innovation Foundation for Graduate Students of Xinjiang Normal University (Grant No. 20101205)
文摘This paper investigates the lowest-energy structures, stabilities and electronic properties of （BAs）n clusters （n=1- 14） by means of the density-functional theory. The results show that the lowest-energy structures undergo a structural change from two-dimensional to three-dimensional when n ： 4. With the increase of the cluster size （n=6）, the （BAs）n clusters tend to adopt cage-like structures, which can be considered as being built from B2As2 and six-membered rings with B-As bond alternative arrangement. The binding energy per atom, second-order energy differences, vertical electron affinity and vertical ionization potential are calculated and discussed. The caculated HOMO-LUMO gaps reveal that the clusters have typical semiconductor characteristics. The analysis of partial density of states suggests that there are strong covalence and molecular characteristics in the clusters.
基金Project supported by the National Key R&D Program of China(Grant Nos.2016YFA0300904 and 2016YFA0202301)the National Natural Science Foundation of China(Grant Nos.11334011,11674366,11674368,and 11761141013)the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant Nos.XDB07010200 and XDPB06)
文摘Exchange coupling between topological insulator and ferromagnetic insulator through proximity effect is strongly attractive for both fundamental physics and technological applications. Here we report a comprehensive investigation on the growth behaviors of prototype topological insulator Bi2Se3 thin film on a single-crystalline LaCoO3 thin film on SrTiO3 substrate, which is a strain-induced ferromagnetic insulator. Different from the growth on other substrates, the Bi2Se3 films with highest quality on LaCoO3 favor a relatively low substrate temperature during growth. As a result, an inverse dependence of carrier mobility with the substrate temperature is found. Moreover, the magnetoresistance and coherence length of weak antilocalization also have a similar inverse dependence with the substrate temperature, as revealed by the magnetotransport measurements. Our experiments elucidate the special behaviors in Bi2Se3/LaCoO3 heterostructures, which provide a good platform for exploring related novel quantum phenomena, and are inspiring for device applications.
文摘In this paper, we perform the density functional theory （DFT） -based calculations by the first-principles pseudopo- tential method to investigate the physical properties of the newly discovered superconductor LaRu2As2 for the first time. The optimized structural parameters are in good agreement with the experimental results. The calculated independent elas- tic constants ensure the mechanical stability of the compound. The calculated Cauchy pressure, Pugh＇s ratio as well as Poisson＇s ratio indicate that LaRu2As2 should behave as a ductile material. Due to low Debye temperature, LaRu2As2 may be used as a thermal barrier coating （TBC） material. The new compound should exhibit metallic nature as its valence bands overlap considerably with the conduction bands. LaRu2As2 is expected to be a soft material and easily machinable because of its low hardness value of 6.8 GPa. The multi-band nature is observed in the calculated Fermi surface. A highly anisotropic combination of ionic, covalent and metallic interactions is expected to be in accordance with charge density calculation.
文摘In this study, nano ferrite materials were produced to replace costive industrial materials<span style="font-family:;" "=""> </span><span style="font-family:Verdana;"><span style="font-size:10.0pt;font-family:" color:#943634;"=""><span style="font-family:Verdana;white-space:normal;">[1]</span></span><span style="font-size:10.0pt;font-family:;" "=""></span><span style="font-size:10.0pt;font-family:" times="" new="" roman","serif";"=""><span></span></span></span><span></span><span><span></span></span><span style="font-family:Verdana;">.</span><span style="font-family:;" "=""> </span><span style="font-family:Verdana;">Ferrite nanoparticles are the interesting material due to their rich and unique physical and chemical properties. They find applications in catalysis, bio-processing, medicine, magnetic recording, adsorption, devices etc.</span><span style="font-family:;" "=""> </span><span style="font-family:;" "=""><span style="font-family:Verdana;">Using co-participation method, five nano ferrite samples Zn</span><sub><span style="font-family:Verdana;">0.5</span></sub><span style="font-family:Verdana;">Mg</span><sub><span style="font-family:Verdana;">0.5-x</span></sub><span style="font-family:Verdana;">Li</span><sub><span style="font-family:Verdana;">2x</span></sub><span style="font-family:Verdana;">Fe</span><sub><span style="font-family:Verdana;">2</span></sub><span style="font-family:Verdana;">O</span><sub><span style="font-family:Verdana;">4</span></sub><span style="font-family:Verdana;"> (x = 0.00, 0.10, 0.20, 0.30 and 0.40) were prepared. The electrical and optical properties of the Zn</span><sub><span style="font-family:Verdana;">0.5</span></sub><span style="font-family:Verdana;">Mg</span><sub><span style="font-family:Verdana;">0.5-x</span></sub><span style="font-family:Verdana;">Li</span><sub><span style="font-family:Verdana;">2x</span></sub><span style="font-family:Verdana;">Fe</span><sub><span style="font-family:Verdana;">2</span></sub><span style="font-family:Verdana;">O</span><sub><span style="font-family:Verdana;">4</span></sub><span style="font-family:Verdana;"> samples were studied using the Ultraviolet-visible (UV-Vis) spectroscopy. The results verified that the formation of the absorption coefficient of the five samples of Zn</span><sub><span style="font-family:Verdana;">0.5</span></sub><span style="font-family:Verdana;">Mg</span><sub><span style="font-family:Verdana;">0.5-x</span></sub><span style="font-family:Verdana;">Li</span><sub><span style="font-family:Verdana;">2x</span></sub><span style="font-family:Verdana;">Fe</span><sub><span style="font-family:Verdana;">2</span></sub><span style="font-family:Verdana;">O</span><sub><span style="font-family:Verdana;">4</span></sub><span style="font-family:Verdana;"> increased with the increase of Lithium (Li</span><sub><span style="font-family:Verdana;">2x</span></sub><span style="font-family:Verdana;">). The energy band gap of the Zn</span><sub><span style="font-family:Verdana;">0.5</span></sub><span style="font-family:Verdana;">Mg</span><sub><span style="font-family:Verdana;">0.5-x</span></sub><span style="font-family:Verdana;">Li</span><sub><span style="font-family:Verdana;">2x</span></sub><span style="font-family:Verdana;">Fe</span><sub><span style="font-family:Verdana;">2</span></sub><span style="font-family:Verdana;">O</span><sub><span style="font-family:Verdana;">4</span></sub><span style="font-family:Verdana;"> samples ranged </span></span><span style="font-family:Verdana;">from</span><span style="font-family:Verdana;"> 3.28 to 3.12</span><span style="font-family:;" "=""> </span><span style="font-family:Verdana;">eV</span><span style="font-family:;" "=""> </span><span style="font-family:Verdana;">[1]</span><span style="font-family:;" "=""></span><span style="font-family:" minion="" pro="" capt","serif";"=""><span></span></span><span style="font-family:Verdana;">.</span><span style="font-family:;" "=""> </span><span style="font-family:;" "=""><span style="font-family:Verdana;">The extinction coefficient (K) for five samples of Zn</span><sub><span style="font-family:Verdana;">0.5</span></sub><span style="font-family:Verdana;">Li</span><sub><span style="font-family:Verdana;">2x</span></sub><span style="font-family:Verdana;">Mg</span><sub><span style="font-family:Verdana;">0.5-x</span></sub><span style="font-family:Verdana;">Fe</span><sub><span style="font-family:Verdana;">2</span></sub><span style="font-family:Verdana;">O</span><sub><span style="font-family:Verdana;">4</span></sub><span style="font-family:Verdana;"> increased with the increase of Lithium (Li</span><sub><span style="font-family:Verdana;">2x</span></sub><span style="font-family:Verdana;">) at 338 nm f</span></span><span style="font-family:Verdana;">ro</span><span style="font-family:Verdana;">m 0.074 to 0.207. The high magnitude of optical conductivity is (1.34</span><span style="font-family:;" "=""> </span><span style="font-family:Verdana;">×</span><span style="font-family:;" "=""> </span><span style="font-family:;" "=""><span style="font-family:Verdana;">10</span><sup><span style="font-family:Verdana;">12</span></sup><span style="font-family:Verdana;"> sec<span style="font-size:10px;"><sup>-1</sup></span></span><span style="font-family:Verdana;">) and the maximum value of electrical conductivity is 42</span></span><span style="font-family:;" "=""> </span><span style="font-family:Verdana;">(Ω<sup>.</sup></span><span style="font-family:;" "=""><span><span style="font-family:Verdana;">cm)<span style="font-size:10px;"><sup>-1</sup></span></span><span style="font-family:Verdana;">. This may due to the electrical and optical properties of lithium.</span></span></span>
基金Supported by the Science and Technology Development Planning Project of Jilin Province(No.201201057)
文摘On the basis of geological investigating work and experimental studies on slide zone soil of one landslide in Tibet,the authors analyzed granulometric composition,clay mineral composition and physical and mechanical properties for the soil in the slide zone.The soil samples are gravel containing fine particle.Particles larger than 2 mm occupy the main proportion with the content 51.5%--68.5%.The relative content of clay minerals is low.The clay minerals are illite smectite mixed layer and kaolinite,and their relative contents are 6%--13% and 4%-11%,respectively.The main mineral ingredient is quartz and the relative content is over 30%.Therefore,the soil’s hydrophily is poor.The cohesion and internal friction angle are high,causing preferable physical-mechanical features of slide zone soil.On the basis of the obtained data,the landslide stability is evaluated by means of limit equilibrium method.The safety factors are 3.191 and 1.92 respectively under both natural and normal water level conditions.The study results show that the landslide is stable.It can provide the appropriate basis and reference for landslide stability evaluation and landslide control in Tibet.
文摘In the paper ,we study longtime dynamic behavior of dissipative soliton equation existence of attractor ,geometrical structure of attractor dynamic behavior under the parametric perturbation of dissipative soliton equation.estimate of fractal dimension of attractor.
基金supported by the National Natural Science Fundation of China(Grant No.51371175)
文摘Recent advances in rare-earth-free hard-magnetic materials including magnetic bulk, thin films, nanocomposites and nanostructures are introduced. Since the costs of the rare-earth metals boosts up the price of the high-performance rare-earth permanent magnets, there is a much revived interest in various types of hard-magnetic materials based on rare-earth-free compounds. The 3d transition metals and their alloys with large coercivity and high Curie temperatures(working temperatures) are expected to overcome the disadvantages of rare-earth magnets. Making rare-earth-free magnets with a large energy product to meet tomorrow's energy needs is still a challenge.
基金Project supported by the National Natural Science Foundation of China （Nos. 50973093, 20772101, 20872124）, Research Fund and the New Teacher Fund for the Doctoral Program of Higher Education of China （Nos. 20094301110004, 200805301013）, Science Foundation of Hunan Province （No. 2009FJ2002）, Scientific Research Fund of Hunan Provincial Education Department （No. 10A 119, 11CY023） and the Postgraduate Science Foundation for Innovation in Hunan Province （No. CX2009B124）.
文摘A red-emitting heteroleptic cyclometalated platinum（II） complex containing an ancillary ligand of pyra- zol-based diketone derivative was synthesized. Its optophysical and electroluminescent properties were studied. Compared to the reported （piq）Pt（acac） complex, this platinum（II） complex exhibited a blue-shifted UV absorption band at 300--450 nm, a low LUMO energy level and improved electroluminescent property. Using this platinum（II） complex as a single doping emitter and a blend of ploy（9,9-dioctylfluorene） and 2-tert-butylphenyl-5-phenyl- 1,3,4-oxadiazole as a host matrix, the fabricated polymer light-emitting devices displayed saturated red emission with a peak at 648 um and a shoulder at 601 nm. Furthermore, the emission quenching of the platinum（II） complex was significantly suppressed in these devices at high current density due to an introduction of the non-planar pyra- zol group into the ancillary ligand.
文摘metry data. The free energy change for charge separation （AGcs） was estimated to be exothermic with --0.51 eV, which favored the formation of charge-separation state. The PET from ZnPc to C60 in ZnPc-C60 made the dyad exhibit stronger reverse saturable absorption performance compared with C60 and the control sample in the Z-scan experiments, which indicated the synergistic effect of two active moieties in the dyad.
基金This work was supported by the National Natural Science Foundation of China （Grant Nos. 61205173, 51272254, 51502292, and 61405206） and the Knowledge Innovation Program of the Chinese Academy of Sciences （No. CXJJ- 15M055）.
文摘A Nd-doped GdNbO4 single crystals have been grown successfully using the Czochralski technique. The chemical etching method was employed to study the defects in the structural morphology of Nd：GdNbO4 crystal with phosphoric acid etchant. Mechanical proper- ties （such as hardness, yield strength, fracture toughness, and brittle index） of the as-grown crystal were system- atically estimated on the basis of the Vickers hardness test for the first time. The transmission spectrum of Nd： GdNbO4 was measured in the wavelength range of 320- 2400 nm at room temperature, and the absorption peaks were assigned. Results hold great significance for further research on Nd：GdNbO4.
基金This work is supported by the Major State Basic Re- search Development Program （No. 2002CB613406）, the National Natural Science Foundation of China （No. 20973078）, the Open Project of State Key Laboratory of Supramolecular Structure and Materials of Jilin Univer- sity （No. SKLSSM200716）. W.-Y.W. thanks the Hong Kong Research Grants Council （No. HKBU202709） and the Hong Kong Baptist University （No. FRG2/08- 09/111） for financial support.
文摘An elaborated theoretical investigation on the optical and electronic properties of three fluorene-based plati- num（II） and iridium（III） cyclometalated complexes Pt-a, Ir-a and lr-b is reported. The geometric and electronic structures of the complexes in the ground state are studied with density functional theory and Hartree Fock ap- proaches, while the lowest triplet excited states are optimized by singles configuration interaction （CIS） methods. At the time-dependent density functional theory （TD-DFT） level, molecular absorption and emission properties were calculated on the basis of optimized ground- and excited-state geometries, respectively. The computational results show that the appearance of triphenylamino （TPA） moiety at the 9-position of fluorene ring favors the hole-creation and leads to red-shifts of absorption and emission spectra. Moreover, Pt-a and Ir-b are nice hole-transporting materials whereas Ir-a has good charge-transfer balance, which render them useful for the realiza- tion of efficient OLEDs （Organic Light-Emitting Diodes）.
基金Research supported by the National Natural Science Foundation of China under Grant 61672005
文摘Based on the range space property （RSP）, the equivalent conditions between nonnegative solutions to the partial sparse and the corresponding weighted l1-norm minimization problem are studied in this paper. Different from other conditions based on the spark property, the mutual coherence, the null space property （NSP） and the restricted isometry property （RIP）, the RSP- based conditions are easier to be verified. Moreover, the proposed conditions guarantee not only the strong equivalence, but also the equivalence between the two problems. First, according to the foundation of the strict complemenrarity theorem of linear programming, a sufficient and necessary condition, satisfying the RSP of the sensing matrix and the full column rank property of the corresponding sub-matrix, is presented for the unique nonnegative solution to the weighted l1-norm minimization problem. Then, based on this condition, the equivalence conditions between the two problems are proposed. Finally, this paper shows that the matrix with the RSP of order k can guarantee the strong equivalence of the two problems.
