ZnO nanorod arrays (NRs) were synthesized on the fluorine-doped SnO2 transparent conductive glass (FTO) by a simple chemical bath deposition (CBD) method combined with alkali-etched method in potassium hydroxide...ZnO nanorod arrays (NRs) were synthesized on the fluorine-doped SnO2 transparent conductive glass (FTO) by a simple chemical bath deposition (CBD) method combined with alkali-etched method in potassium hydroxide (KOH) solution. X-ray diffraction (XRD), scanning electron microscopy (SEM) and current-voltage (I-V) curve were used to characterize the structure, morphologies and optoelectronic properties. The results demonstrated that ZnO NRs had wurtzite structures, the morphologies and photovoltaic properties of ZnO NRs were closely related to the concentration of KOH and etching time, well-aligned and uniformly distributed ZnO NRs were obtained after etching with 0.1 mol/L KOH for 1 h. ZnO NRs treated by KOH had been proved to have superior photovoltaic properties compared with high density ZnO NRs. When using ZnO NRs etched with 0.1 mol/L KOH for 1 h as the anode of solar cell, the conversion efficiency, short circuit current and open circuit voltage, compared with the unetched ZnO NRs, increased by 0.71%, 2.79 mA and 0.03 V, respectively.展开更多
Aluminate-based coupling agent was added as a compatibilizer to make the chemical modification of wood powder. The mechanical properties and morphology of wood powder/polypropylene composites were studied. The results...Aluminate-based coupling agent was added as a compatibilizer to make the chemical modification of wood powder. The mechanical properties and morphology of wood powder/polypropylene composites were studied. The results showed that the compatibilizer can increase the impact strength of the wood/polypropylene composites, but it has a slightly negative effect on the tensile and flexural strength. For dynamic mechanical properties and Differential Scanning Calorimetry, Aluminate-based coupling agent can slightly increase the storage modulus and loss modulus, and decrease the melt point and the Calorie of Melt. Scanning electron microscopy showed that Aluminate-based coupling agent had a stronger affinity between the wood and polypropylene surfaces. These results suggested that Aluminate-based coupling agent may play a useful role in improving wood powder/polypropylene composites properties.展开更多
Northeast of China and Jiangsu Province are major production areas of japonica rice in China.Rice from northeast of China is well-known for its good-eating and appearance quality,and that from Jiangsu Province is view...Northeast of China and Jiangsu Province are major production areas of japonica rice in China.Rice from northeast of China is well-known for its good-eating and appearance quality,and that from Jiangsu Province is viewed as inferior.However,little is known concerning the difference in physicochemical and sensory properties of rice between the major two production areas.Analysis of 16 commercial rice samples showed marked differences in physicochemical properties,including chalky grain rate,contents of amylose and protein and pasting properties between the two main areas.Northeastern rice contained more shortchain amylopectin as compared with Jiangsu rice.However,Jiangsu rice is comparable to northeastern rice in terms of sensory quality including overall acceptability and textural properties of springiness,stickiness and hardness as evaluated by trained panel.Our results indicated the limitation of conventional index of physicochemical properties,and suggested the necessity of identification of new factors controlling rice sensory property.In addition,the taste analyzer from Japan demonstrates limitation in distinguishing the differences between northeastern and Jiangsu rice,and therefore needs localization to fit China.展开更多
S-doped and Al-doped GaSe crystals are promising materials for their applications in nonlinear frequency conversion devices. The optical and defect properties of pure, S-doped, and Al-doped GaSe crystals were studied ...S-doped and Al-doped GaSe crystals are promising materials for their applications in nonlinear frequency conversion devices. The optical and defect properties of pure, S-doped, and Al-doped GaSe crystals were studied by using photoluminescence(PL) and Fourier transform infrared spectroscopy(FT-IR). The micro-topography of(0001) face of these samples was observed by using scanning electron microscope(SEM) to investigate the influence of the doped defects on the intralayer and interlayer chemical bondings. The doped S or Al atoms form the SSe^0 or AlGa^+1) substitutional defects in the layer GaSe structure, and the positive center of AlGa-^+1 could induce defect complexes. The incorporations of S and Al atoms can change the optical and mechanical properties of the GaSe crystal by influencing the chemical bonding of the layer structure. The study results may provide guidance for the crystal growth and further applications of S-doped and Al-doped GaSe crystals.展开更多
Two coordination compounds, namely [Ce(3,5-Br2BC)3(3,5-HBrzBC)]n (1) and [Zn(3,5-Br2BC)2(phen)] (2, 3,5-HBr2BC = 3,5-dibromobenzoic acid, phen = 1,10-phenanthroline), were assembled. Single-crystal X-ray d...Two coordination compounds, namely [Ce(3,5-Br2BC)3(3,5-HBrzBC)]n (1) and [Zn(3,5-Br2BC)2(phen)] (2, 3,5-HBr2BC = 3,5-dibromobenzoic acid, phen = 1,10-phenanthroline), were assembled. Single-crystal X-ray diffraction studies show that compound 1 possesses a ID chain coordination network, which is further extended into a 3D supramolecular architecture via Br..'Br and Br'"O halogen bonding. Compound 2 consists of a mononuclear molecule, which is assembled to a 3D supramolecular framework through C-H..-O hydrogen bond, π-π stacking interactions and Br..π halogen bonding. Luminescent and magnetic properties of both compounds have also been studied.展开更多
Centrifugal casting was applied to produce cylindrical castings using SiCp/Al composite slurry,which contained 20%SiC particles.The castings comprised a particle free zone and a particle rich zone.The amount of SiC pa...Centrifugal casting was applied to produce cylindrical castings using SiCp/Al composite slurry,which contained 20%SiC particles.The castings comprised a particle free zone and a particle rich zone.The amount of SiC particles had a dramatic transformation from the particle rich zone to the particle free zone,and the maximum content of SiC particles in the particle rich zone reached up to 40 vol%.The ultimate tensile strength(UTS) of the as-cast SiCp / Al composites in the particle rich zone was 143 MPa,and the fracture was caused by the desorption of SiC particles from matrix alloy.The coefficient of thermal expansion(CTE) of the SiC_p / Al composites in the range of 20 and 100 ℃ was determined as 16.67×10^(-6) s^(-1),and the experimental CTE was lower than the predicted data based on the Kerner's model.The results show that the decrease in CTE in the case of the composites at high temperature stage can be attributed to the solute concentration of Si in Al and the plastic deformation of the matrix alloy in the composites with void architecture.展开更多
In the present study,the chemical and mechanical properties and the thermal expansion of a carbon nanotube(CNT)-based crystalline nano-aluminum(nano Al) composite were reported.The properties of nanocomposites wer...In the present study,the chemical and mechanical properties and the thermal expansion of a carbon nanotube(CNT)-based crystalline nano-aluminum(nano Al) composite were reported.The properties of nanocomposites were tailored by incorporating CNTs into the nano Al matrix using a physical mixing method.The elastic moduli and the coefficient of thermal expansion(CTE) of the nanocomposites were also estimated to understand the effects of CNT reinforcement in the Al matrix.Microstructural characterization of the nanocomposite reveals that the CNTs are dispersed and embedded in the Al matrix.The experimental results indicate that the incorporation of CNTs into the nano Al matrix results in the increase in hardness and elastic modulus along with a concomitant decrease in the coefficient of thermal expansion The hardness and elastic modulus of the nanocomposite increase by 21%and 20%,respectively,upon CNT addition.The CTE of CNT/A1 nanocomposite decreases to 70%compared with that of nano Al.展开更多
The mechanical properties, thermal properties, electronic structures, and optical properties of the defect perovskites Cs2SnX6(X = Cl, Br, I) were investigated by first-principles calculation using PBE and HSE06 hyb...The mechanical properties, thermal properties, electronic structures, and optical properties of the defect perovskites Cs2SnX6(X = Cl, Br, I) were investigated by first-principles calculation using PBE and HSE06 hybrid functional. The optic band gaps based on HSE06 are 3.83 eV for Cs2SnCl6, 2.36 eV for Cs2SnBr6, and 0.92 eV for Cs2SnI6, which agree with the experimental results. The Cs2SnCl6, Cs2SnBr6, and Cs2SnI6 are mechanically stable and they are all anisotropic and ductile in nature. Electronic structures calculations show that the conduction band consists mainly of hybridization between the halogen p orbitals and Sn 5s orbitals, whereas the valence band is composed of the halogen p orbitals. Optic properties indicate that these three compounds exhibit good optical absorption in the ultraviolet region, and the absorption spectra red shift with the increase in the number of halogen atoms. The defect perovskites are good candidates for probing the lead-free and high power conversion efficiency of solar cells.展开更多
In this article, a computational analysis has been performed on the structural properties and predominantly on the electronic properties of the α-CuSe (klockmannite) using density functional theory. The studies in ...In this article, a computational analysis has been performed on the structural properties and predominantly on the electronic properties of the α-CuSe (klockmannite) using density functional theory. The studies in this work show that the best structural results, in comparison to the experimental values, belong to the PBEsol-GGA and WC-GGA functionals. However, the best results for the bulk modulus and density of states (DOSs) are related to the local density approximation (LDA) functional. Through utilized approaches, the LDA is chosen to investigate the electronic structure. The results of the electronic properties and geometric optimization of α-CuSe respectively show that this compound is conductive and non-magnetic. The curvatures of the energy bands crossing the Fermi level explicitly reveal that major charge carriers in CuSe are holes, whose density is estimated to be 0.86×1022 hole/cm3. In particular, the Fermi surfaces in the first Brillouin zone demonstrate interplane conductivity between (001) planes. Moreover, the charge carriers among them are electrons and holes simultaneously. The conductivity in CuSe is mainly due to the hybridization between the d orbitals of Cu atoms and the p orbitals of Se atoms. The former orbitals have the dual nature of localization and itinerancy.展开更多
The effect of Ga_2O_3 on the structure and properties of calcium aluminate glasses fabricated by vacuum melting process was investigated by Raman spectrum, differential scanning calorimeter(DSC), and infrared spectr...The effect of Ga_2O_3 on the structure and properties of calcium aluminate glasses fabricated by vacuum melting process was investigated by Raman spectrum, differential scanning calorimeter(DSC), and infrared spectrum methods. The results show that calcium aluminate glass network only consists of [AlO_4] tetrahedral units. With the gradual addition of Ga_2O_3, the quantity of [GaO_4] tetrahedral units increases. Substitution of Ga_2O_3 for Al_2O_3 results in a decrease in Tg, Tx, and Tp, and an increase in the thermal stable index ΔT. Similarly, the absorption band around 3.0 μm obviously reduces and the transparency in 4.0-6.0 μm rapidly increases with increasing Ga_2O_3 content. However, the chemical stability of calcium aluminate glasses decreases if Ga_2O_3 is introduced due to the increasing of [GaO_4] units in the glass network.展开更多
The ab initio method has been performed to explore the elastic and optical properties of Al3Sc compound, based on a plane wave pseudopotential method. It can be seen that the calculated equilibrium lattice parameter a...The ab initio method has been performed to explore the elastic and optical properties of Al3Sc compound, based on a plane wave pseudopotential method. It can be seen that the calculated equilibrium lattice parameter and elastic constants are in reasonable agreement with the previous experimental data. The elastic constants satisfy the requirement for mechanical stability in the cubic structure of the Al3Sc compound. The optical property calculations show that a strong absorptive peak exists from O-15eV and a relative small absorptive peak exists around 30eV. The form is caused by the optical transitions between high s, p, and d bands, and the latter results from the optical transitions from high s, p, and d bands to the low 2p band.展开更多
This study investigated the effect of adding germinated black cumin seed extract(GBSE)in the amounts of 0,50,75,and 100 mg/100 ml milk,which are mentioned in abbreviate as C,GBSE50,GBSE75,and GBSE100,respectively,on t...This study investigated the effect of adding germinated black cumin seed extract(GBSE)in the amounts of 0,50,75,and 100 mg/100 ml milk,which are mentioned in abbreviate as C,GBSE50,GBSE75,and GBSE100,respectively,on the physicochemical,antioxidant,antidiabetic and sensory properties of yogurt.In the present research,pH,titratable acidity(TA),syneresis,water-holding capacity(WHC),viscosity,total phenolic content(TPC),antioxidant activity(DPPH,ABTS radicals scavenging activity and FIC assay),α-amylase andα-glucosidase inhibitory effect and sensory attributes(taste,odor,texture,color,and overall acceptance)of fortified yogurts during 14 days of storage at 4℃ were determined.According to study results,fortification,even in the lowest amount(50 mg/100 ml milk),improved the qualitative and bioactive properties of yogurt significantly(p<0.05).All samples that received acceptable sensory scores were appreciated.However,GBSE50 and 75 showed no significant difference(p>0.05)after 14 days of storage compared to the control.Due to the results of all experiments,fortifying yogurt with the addition of 75 mg of GBSE in 100 ml milk is recommended to improve the qualitative and bioactive properties of the obtained functional yogurt.展开更多
The novel linear, circular, hooped, and helical molecules based on oligo[8]thio- phene were theoretically studied for the applications of charge transfer devices. To investigate the influence of topology for oligo[8]t...The novel linear, circular, hooped, and helical molecules based on oligo[8]thio- phene were theoretically studied for the applications of charge transfer devices. To investigate the influence of topology for oligo[8]thiophene derivatives, the geometry structures, frontier molecular orbital (FMO) energies, charge transport properties, and stability property were predicted by density functional theory methods. The calculated results reported herein show that the oligo[8]thiophene derivative with linear structure has smaller energy gap, and fused oligo[8]thiophene derivative with circular structure has the smallest reorganization energy among the designed molecules. We have also studied the stability properties of the designed molecules, and oligo[8]thiophene derivatives are more stable tharJ the fused oligo[8]thiophene derivatives.展开更多
Ceramic materials were investigated as thermal barrier coatings and electrolytes. Electrophoretic deposition(EPD) and physical vapor deposition(PVD) were employed to fabricate samples, and the mechanical propertie...Ceramic materials were investigated as thermal barrier coatings and electrolytes. Electrophoretic deposition(EPD) and physical vapor deposition(PVD) were employed to fabricate samples, and the mechanical properties and microstructure were examined by nanoindentation and microscopy, respectively. Yttria-stabilized zirconia/alumina(YSZ/Al2O3) composite coatings, a candidate for thermal barrier coatings, yield a kinky, rather than smooth, load–displacement curve. Scanning electron microscope(SEM) examination reveals that the kinky curve is because of the porous microstructure and cracks are caused by the compression of the indenter. Li0.34La0.51 Ti O2.94(LLTO) on Si/Sr Ru O3(Si/SRO) substrates, an ionic conductor in nature, demonstrates electronic performance. Although SEM images show a continuous and smooth microstructure, a close examination of the microstructure by transmission electron microscopy(TEM) reveals that the observed spikes indicate electronic performance. Therefore, we can conclude that ceramic coatings could serve multiple purposes but their properties are microstructure-dependent.展开更多
Using the first-principles calculations based on spin density functional theory(DFT), we investigate the structure,elastic properties, and electronic structure of Pnnm-CrB4. It is found that Pnnm-CrB4 is thermodynam...Using the first-principles calculations based on spin density functional theory(DFT), we investigate the structure,elastic properties, and electronic structure of Pnnm-CrB4. It is found that Pnnm-CrB4 is thermodynamically and mechanically stable. The calculated elastic properties such as the bulk modulus, shear modulus, Young's modulus, and Poisson's ratio indicate that CrB4 is an incompressible material. Vicker's hardness of Pnnm-CrB4 is estimated to be 26.3 GPa, which is in good agreement with the experimental values. The analysis of the investigated electronic properties shows that PnnmCrB4 has the metallic character and there exist strong B–B and Cr–B bonds in the compound, which are further confirmed by Bader's quantum theory of atoms in molecules(QTAIM). Thermodynamic properties are also investigated.展开更多
The elastic properties, thermodynamic and electronic structures of Mg_2La were investigated by using first-principles. The calculated results show that pressure affects the elastic constants of C_(11) more than that o...The elastic properties, thermodynamic and electronic structures of Mg_2La were investigated by using first-principles. The calculated results show that pressure affects the elastic constants of C_(11) more than that of C_(12) and C_(44). Specifically, higher pressure leads to greater bulk modulus(B), shear modulus(G), and elastic modulus(E). We predict B/G and anisotropy factor A based on the calculated elastic constants. The Debye temperature also increases with increasing pressure. Based on the quasi-harmonic Debye model, we examined the thermodynamic properties. These properties include the normalized volume(V/V_0), bulk modulus(B), heat capacity(C_v), thermal expansion coefficient(α), and Debye temperature(■). Finally, the electronic structures associated with the density of states(DOS) and Mulliken population are analyzed.展开更多
The structural stability, thermodynamic and optical properties of delafossite CuAlO2 were investigated using the norm-conserving pseudopotential technique based on the fi rst-principle density-functional theory. The g...The structural stability, thermodynamic and optical properties of delafossite CuAlO2 were investigated using the norm-conserving pseudopotential technique based on the fi rst-principle density-functional theory. The ground-state properties obtained by minimizing the total energy were in favorable agreement with previous works. By using the quasi-harmonic Debye model, the thermodynamic properties including the Debye temperature QD, heat capacity CV, thermal expansion coeffi cient a, and Grüneisen parameter g were successfully obtained in the temperature range from 0 to 1 000 K and pressure range from 0 to 80 GPa, respectively. The optical properties including dielectric function e(v), absorption coeffi cient a(v), refl ectivity coeffi cient R(v), and refractive index n(v) were also calculated and analyzed.展开更多
Structural, anisotropic, and thermodynamic properties of Imm2-BCN were studied based on density function theory with the ultrasoft psedopotential scheme in the frame of the generalized gradient approximation(GGA). T...Structural, anisotropic, and thermodynamic properties of Imm2-BCN were studied based on density function theory with the ultrasoft psedopotential scheme in the frame of the generalized gradient approximation(GGA). The elastic constants were confirmed that the predicted Imm2-BCN is mechanically stable. The anisotropy of elastic properties were also studied systematically. The anisotropy studies of Young's modulus, shear modulus, linear compressibility, and Poisson's ratio show that the Imm2-BCN exhibits a large anisotropy. Through the quasi-harmonic Debye model, the relations between the equilibrium volume V, thermal expansion α, the heat capacity C_V and CP, the Grüneisen parameter γ, and the Debye temperature Θ_D with pressure P and temperature T were also studied systematically.展开更多
We investigate the magnetic properties of Co-doped Cu_2O. We studied first the electronic and structural properties of Cu_2O using the optimization of the lattice constant which is 4.18 . The calculated gap is found b...We investigate the magnetic properties of Co-doped Cu_2O. We studied first the electronic and structural properties of Cu_2O using the optimization of the lattice constant which is 4.18 . The calculated gap is found between 0.825 eV and1.5 eV, these values are in good agreement with the experimental results. The Co atoms are inserted in Cu_2O by means of the density functional theory(DFT) using LSDA, LSDA +U, and LSDA + MBJ approximations in the WIEN2 k code, based on the supercell model by setting up 12, 24, and 48 atoms in(1×1 × 2),(1 × 2 × 2), and(2 × 2×2) supercells respectively with one or two copper atoms being replaced by cobalt atoms. The energy difference between the ferromagnetic and antiferromagnetic coupling of the spins located on the substitute Co has been calculated in order to obtain better insight into the magnetic exchange coupling for this particular compound. The studied compound exhibits stable integer magnetic moments of 2 μBand 4 μBwhen it is doped with 2 atoms of Co. Optical properties have also been worked out. The results obtained in this study demonstrate the importance of the magnetic effect in Cu_2O.展开更多
Sweet potatoes have become a research focus in recent years, due to their particular nutritional and functional qualities. Considering yoghurt is one of the most popular dairy products, sweet potato supplementation wi...Sweet potatoes have become a research focus in recent years, due to their particular nutritional and functional qualities. Considering yoghurt is one of the most popular dairy products, sweet potato supplementation will play a significant impact on the produced yoghurt texture it will also add attractive orange colour to the final product. The article focused on the replacement of the stabilizers used in the manufacture of yoghurt with sweet potato flour dehydrated in a lab (SPFL) due to its functional features and a less expensive alternative and the improvement of yoghurt colour due to the presence of anthocyanin pigment. In order to reach these goals, experimental yoghurt was fortified with 0, 0.5, 1, 2, and 4 g SPFL/100g cow milk (%) and stored at 4°C for 14 days. The obtained data were then compared with commercial yoghurt samples (CS1, CS2, CS3, and CS4). Sensory evaluation revealed that the 2% SPFL, CS1, and CS3 obtained higher scores than the other treatments. The fat content of the yoghurts was identical whereas, the other physicochemical parameters and water holding capacity (WHC %) levels varied. SPFL supplementation had a significant impact on the rheological properties of yoghurt production, allowing sweet potato flour to replace the industrial stabiliser. Scanning Electron Micrograph (SEM) of yoghurt enriched with SPFL revealed denser and smaller gaps, as well as the presence of sweet potato globules embedded in and attached to the gel matrix. The results obtained in the present research imply that sweet potatoes can be used to produce a kind of cohesive and gummy yoghurt that can be used instead of industrial stabilizers.展开更多
基金Project (21171027) supported by the National Natural Science Foundation of ChinaProject (K1001020-11) supported by the Science and Technology Key Project of Changsha City, ChinaProject ([2010]70) supported by Science and Technology Innovative Research Team in Higher Educational Institutions of Hunan Province, China
文摘ZnO nanorod arrays (NRs) were synthesized on the fluorine-doped SnO2 transparent conductive glass (FTO) by a simple chemical bath deposition (CBD) method combined with alkali-etched method in potassium hydroxide (KOH) solution. X-ray diffraction (XRD), scanning electron microscopy (SEM) and current-voltage (I-V) curve were used to characterize the structure, morphologies and optoelectronic properties. The results demonstrated that ZnO NRs had wurtzite structures, the morphologies and photovoltaic properties of ZnO NRs were closely related to the concentration of KOH and etching time, well-aligned and uniformly distributed ZnO NRs were obtained after etching with 0.1 mol/L KOH for 1 h. ZnO NRs treated by KOH had been proved to have superior photovoltaic properties compared with high density ZnO NRs. When using ZnO NRs etched with 0.1 mol/L KOH for 1 h as the anode of solar cell, the conversion efficiency, short circuit current and open circuit voltage, compared with the unetched ZnO NRs, increased by 0.71%, 2.79 mA and 0.03 V, respectively.
基金This study was supported by Introduce Foreign Advanced Technology Project (2001-1).
文摘Aluminate-based coupling agent was added as a compatibilizer to make the chemical modification of wood powder. The mechanical properties and morphology of wood powder/polypropylene composites were studied. The results showed that the compatibilizer can increase the impact strength of the wood/polypropylene composites, but it has a slightly negative effect on the tensile and flexural strength. For dynamic mechanical properties and Differential Scanning Calorimetry, Aluminate-based coupling agent can slightly increase the storage modulus and loss modulus, and decrease the melt point and the Calorie of Melt. Scanning electron microscopy showed that Aluminate-based coupling agent had a stronger affinity between the wood and polypropylene surfaces. These results suggested that Aluminate-based coupling agent may play a useful role in improving wood powder/polypropylene composites properties.
基金supported by the Program for New Century Excellent Talents in University, China (NCET-10-0472)the National Natural Science Foundation of China (30971733 and 31171485)
文摘Northeast of China and Jiangsu Province are major production areas of japonica rice in China.Rice from northeast of China is well-known for its good-eating and appearance quality,and that from Jiangsu Province is viewed as inferior.However,little is known concerning the difference in physicochemical and sensory properties of rice between the major two production areas.Analysis of 16 commercial rice samples showed marked differences in physicochemical properties,including chalky grain rate,contents of amylose and protein and pasting properties between the two main areas.Northeastern rice contained more shortchain amylopectin as compared with Jiangsu rice.However,Jiangsu rice is comparable to northeastern rice in terms of sensory quality including overall acceptability and textural properties of springiness,stickiness and hardness as evaluated by trained panel.Our results indicated the limitation of conventional index of physicochemical properties,and suggested the necessity of identification of new factors controlling rice sensory property.In addition,the taste analyzer from Japan demonstrates limitation in distinguishing the differences between northeastern and Jiangsu rice,and therefore needs localization to fit China.
基金Project supported by Knowledge Innovation Program of the Chinese Academy of Sciences(Grant No.CXJJ-16M128)
文摘S-doped and Al-doped GaSe crystals are promising materials for their applications in nonlinear frequency conversion devices. The optical and defect properties of pure, S-doped, and Al-doped GaSe crystals were studied by using photoluminescence(PL) and Fourier transform infrared spectroscopy(FT-IR). The micro-topography of(0001) face of these samples was observed by using scanning electron microscope(SEM) to investigate the influence of the doped defects on the intralayer and interlayer chemical bondings. The doped S or Al atoms form the SSe^0 or AlGa^+1) substitutional defects in the layer GaSe structure, and the positive center of AlGa-^+1 could induce defect complexes. The incorporations of S and Al atoms can change the optical and mechanical properties of the GaSe crystal by influencing the chemical bonding of the layer structure. The study results may provide guidance for the crystal growth and further applications of S-doped and Al-doped GaSe crystals.
基金supported by the Natural Science Foundation of Shanxi Province(No.2013011011-6)the Subject Team of Taiyuan University of Science and Technology
文摘Two coordination compounds, namely [Ce(3,5-Br2BC)3(3,5-HBrzBC)]n (1) and [Zn(3,5-Br2BC)2(phen)] (2, 3,5-HBr2BC = 3,5-dibromobenzoic acid, phen = 1,10-phenanthroline), were assembled. Single-crystal X-ray diffraction studies show that compound 1 possesses a ID chain coordination network, which is further extended into a 3D supramolecular architecture via Br..'Br and Br'"O halogen bonding. Compound 2 consists of a mononuclear molecule, which is assembled to a 3D supramolecular framework through C-H..-O hydrogen bond, π-π stacking interactions and Br..π halogen bonding. Luminescent and magnetic properties of both compounds have also been studied.
基金Funded by the National Natural Science Foundation of China(No.51174244)the Foundational and Cutting-edge Research Plan of Chongqing,China(No.csts2013jcyj A50014)the Fundamental Research Funds for Central University,China(No.CDJZR12240056)
文摘Centrifugal casting was applied to produce cylindrical castings using SiCp/Al composite slurry,which contained 20%SiC particles.The castings comprised a particle free zone and a particle rich zone.The amount of SiC particles had a dramatic transformation from the particle rich zone to the particle free zone,and the maximum content of SiC particles in the particle rich zone reached up to 40 vol%.The ultimate tensile strength(UTS) of the as-cast SiCp / Al composites in the particle rich zone was 143 MPa,and the fracture was caused by the desorption of SiC particles from matrix alloy.The coefficient of thermal expansion(CTE) of the SiC_p / Al composites in the range of 20 and 100 ℃ was determined as 16.67×10^(-6) s^(-1),and the experimental CTE was lower than the predicted data based on the Kerner's model.The results show that the decrease in CTE in the case of the composites at high temperature stage can be attributed to the solute concentration of Si in Al and the plastic deformation of the matrix alloy in the composites with void architecture.
基金supported by the Defence Research and Development Organization, New Delhi (No.ARMREB/CDSW/2011/135)
文摘In the present study,the chemical and mechanical properties and the thermal expansion of a carbon nanotube(CNT)-based crystalline nano-aluminum(nano Al) composite were reported.The properties of nanocomposites were tailored by incorporating CNTs into the nano Al matrix using a physical mixing method.The elastic moduli and the coefficient of thermal expansion(CTE) of the nanocomposites were also estimated to understand the effects of CNT reinforcement in the Al matrix.Microstructural characterization of the nanocomposite reveals that the CNTs are dispersed and embedded in the Al matrix.The experimental results indicate that the incorporation of CNTs into the nano Al matrix results in the increase in hardness and elastic modulus along with a concomitant decrease in the coefficient of thermal expansion The hardness and elastic modulus of the nanocomposite increase by 21%and 20%,respectively,upon CNT addition.The CTE of CNT/A1 nanocomposite decreases to 70%compared with that of nano Al.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.51572219 and 11447030)the Natural Science Foundation of Shaanxi Province of China(Grant No.2015JM1018)Graduate’s Innovation Fund of Northwest University of China(Grant No.YJG15007)
文摘The mechanical properties, thermal properties, electronic structures, and optical properties of the defect perovskites Cs2SnX6(X = Cl, Br, I) were investigated by first-principles calculation using PBE and HSE06 hybrid functional. The optic band gaps based on HSE06 are 3.83 eV for Cs2SnCl6, 2.36 eV for Cs2SnBr6, and 0.92 eV for Cs2SnI6, which agree with the experimental results. The Cs2SnCl6, Cs2SnBr6, and Cs2SnI6 are mechanically stable and they are all anisotropic and ductile in nature. Electronic structures calculations show that the conduction band consists mainly of hybridization between the halogen p orbitals and Sn 5s orbitals, whereas the valence band is composed of the halogen p orbitals. Optic properties indicate that these three compounds exhibit good optical absorption in the ultraviolet region, and the absorption spectra red shift with the increase in the number of halogen atoms. The defect perovskites are good candidates for probing the lead-free and high power conversion efficiency of solar cells.
基金performed based on research project number 2054361 in the University of Isfahan (UI), Isfahan, Iran
文摘In this article, a computational analysis has been performed on the structural properties and predominantly on the electronic properties of the α-CuSe (klockmannite) using density functional theory. The studies in this work show that the best structural results, in comparison to the experimental values, belong to the PBEsol-GGA and WC-GGA functionals. However, the best results for the bulk modulus and density of states (DOSs) are related to the local density approximation (LDA) functional. Through utilized approaches, the LDA is chosen to investigate the electronic structure. The results of the electronic properties and geometric optimization of α-CuSe respectively show that this compound is conductive and non-magnetic. The curvatures of the energy bands crossing the Fermi level explicitly reveal that major charge carriers in CuSe are holes, whose density is estimated to be 0.86×1022 hole/cm3. In particular, the Fermi surfaces in the first Brillouin zone demonstrate interplane conductivity between (001) planes. Moreover, the charge carriers among them are electrons and holes simultaneously. The conductivity in CuSe is mainly due to the hybridization between the d orbitals of Cu atoms and the p orbitals of Se atoms. The former orbitals have the dual nature of localization and itinerancy.
基金Funded by the National Natural Science Foundation of China(No.60808024)
文摘The effect of Ga_2O_3 on the structure and properties of calcium aluminate glasses fabricated by vacuum melting process was investigated by Raman spectrum, differential scanning calorimeter(DSC), and infrared spectrum methods. The results show that calcium aluminate glass network only consists of [AlO_4] tetrahedral units. With the gradual addition of Ga_2O_3, the quantity of [GaO_4] tetrahedral units increases. Substitution of Ga_2O_3 for Al_2O_3 results in a decrease in Tg, Tx, and Tp, and an increase in the thermal stable index ΔT. Similarly, the absorption band around 3.0 μm obviously reduces and the transparency in 4.0-6.0 μm rapidly increases with increasing Ga_2O_3 content. However, the chemical stability of calcium aluminate glasses decreases if Ga_2O_3 is introduced due to the increasing of [GaO_4] units in the glass network.
基金the Hunan Provincial Natural Science Foundation of China (No. 07JJ3117)Chinese Postdoctoral Scientific Foundation (No. 20070410303).
文摘The ab initio method has been performed to explore the elastic and optical properties of Al3Sc compound, based on a plane wave pseudopotential method. It can be seen that the calculated equilibrium lattice parameter and elastic constants are in reasonable agreement with the previous experimental data. The elastic constants satisfy the requirement for mechanical stability in the cubic structure of the Al3Sc compound. The optical property calculations show that a strong absorptive peak exists from O-15eV and a relative small absorptive peak exists around 30eV. The form is caused by the optical transitions between high s, p, and d bands, and the latter results from the optical transitions from high s, p, and d bands to the low 2p band.
基金financial support from the University of ZanjanImam Khomeini International University,Iran.
文摘This study investigated the effect of adding germinated black cumin seed extract(GBSE)in the amounts of 0,50,75,and 100 mg/100 ml milk,which are mentioned in abbreviate as C,GBSE50,GBSE75,and GBSE100,respectively,on the physicochemical,antioxidant,antidiabetic and sensory properties of yogurt.In the present research,pH,titratable acidity(TA),syneresis,water-holding capacity(WHC),viscosity,total phenolic content(TPC),antioxidant activity(DPPH,ABTS radicals scavenging activity and FIC assay),α-amylase andα-glucosidase inhibitory effect and sensory attributes(taste,odor,texture,color,and overall acceptance)of fortified yogurts during 14 days of storage at 4℃ were determined.According to study results,fortification,even in the lowest amount(50 mg/100 ml milk),improved the qualitative and bioactive properties of yogurt significantly(p<0.05).All samples that received acceptable sensory scores were appreciated.However,GBSE50 and 75 showed no significant difference(p>0.05)after 14 days of storage compared to the control.Due to the results of all experiments,fortifying yogurt with the addition of 75 mg of GBSE in 100 ml milk is recommended to improve the qualitative and bioactive properties of the obtained functional yogurt.
基金Supported by the National Natural Science Foundation of China(No.21302062)the Science Foundation for Young Teachers of Jilin Agricultural University(No.201219)
文摘The novel linear, circular, hooped, and helical molecules based on oligo[8]thio- phene were theoretically studied for the applications of charge transfer devices. To investigate the influence of topology for oligo[8]thiophene derivatives, the geometry structures, frontier molecular orbital (FMO) energies, charge transport properties, and stability property were predicted by density functional theory methods. The calculated results reported herein show that the oligo[8]thiophene derivative with linear structure has smaller energy gap, and fused oligo[8]thiophene derivative with circular structure has the smallest reorganization energy among the designed molecules. We have also studied the stability properties of the designed molecules, and oligo[8]thiophene derivatives are more stable tharJ the fused oligo[8]thiophene derivatives.
基金financially supported by the Natural Science Foundation of Hebei Province,China(No.E2013502272)
文摘Ceramic materials were investigated as thermal barrier coatings and electrolytes. Electrophoretic deposition(EPD) and physical vapor deposition(PVD) were employed to fabricate samples, and the mechanical properties and microstructure were examined by nanoindentation and microscopy, respectively. Yttria-stabilized zirconia/alumina(YSZ/Al2O3) composite coatings, a candidate for thermal barrier coatings, yield a kinky, rather than smooth, load–displacement curve. Scanning electron microscope(SEM) examination reveals that the kinky curve is because of the porous microstructure and cracks are caused by the compression of the indenter. Li0.34La0.51 Ti O2.94(LLTO) on Si/Sr Ru O3(Si/SRO) substrates, an ionic conductor in nature, demonstrates electronic performance. Although SEM images show a continuous and smooth microstructure, a close examination of the microstructure by transmission electron microscopy(TEM) reveals that the observed spikes indicate electronic performance. Therefore, we can conclude that ceramic coatings could serve multiple purposes but their properties are microstructure-dependent.
基金Project supported by the National Natural Science Foundation of China(Grant No.U1304111)Program for Science&Technology Innovation Talents in Universities of Henan Province,China(Grant No.14HASTIT039)the Innovation Team of Henan University of Science and Technology,China(Grant No.2015XTD001)
文摘Using the first-principles calculations based on spin density functional theory(DFT), we investigate the structure,elastic properties, and electronic structure of Pnnm-CrB4. It is found that Pnnm-CrB4 is thermodynamically and mechanically stable. The calculated elastic properties such as the bulk modulus, shear modulus, Young's modulus, and Poisson's ratio indicate that CrB4 is an incompressible material. Vicker's hardness of Pnnm-CrB4 is estimated to be 26.3 GPa, which is in good agreement with the experimental values. The analysis of the investigated electronic properties shows that PnnmCrB4 has the metallic character and there exist strong B–B and Cr–B bonds in the compound, which are further confirmed by Bader's quantum theory of atoms in molecules(QTAIM). Thermodynamic properties are also investigated.
基金Project(51574176)supported by the National Natural Science Foundation of ChinaProject(143020142-S)supported by the Program for the Top Young Academic Leaders of Higher Learning Institutions of Shanxi Province(TYAL),ChinaProject(201603D421028)supported by the Key Research and Development Program of Shanxi Province(International Cooperative Project),China
文摘The elastic properties, thermodynamic and electronic structures of Mg_2La were investigated by using first-principles. The calculated results show that pressure affects the elastic constants of C_(11) more than that of C_(12) and C_(44). Specifically, higher pressure leads to greater bulk modulus(B), shear modulus(G), and elastic modulus(E). We predict B/G and anisotropy factor A based on the calculated elastic constants. The Debye temperature also increases with increasing pressure. Based on the quasi-harmonic Debye model, we examined the thermodynamic properties. These properties include the normalized volume(V/V_0), bulk modulus(B), heat capacity(C_v), thermal expansion coefficient(α), and Debye temperature(■). Finally, the electronic structures associated with the density of states(DOS) and Mulliken population are analyzed.
基金Funded by the National Natural Science Foundation of China(Nos.11204192 and 11104099)the National Key Laboratory Fund for Shock Wave and Detonation Physics Research of the China Academy of Engineering Physics(No.9140C671101110C6709)+1 种基金the Defense Industrial Technology Development Program of China(No.B1520110002)the National Basic Research Program of China(No.2010CB731600)
文摘The structural stability, thermodynamic and optical properties of delafossite CuAlO2 were investigated using the norm-conserving pseudopotential technique based on the fi rst-principle density-functional theory. The ground-state properties obtained by minimizing the total energy were in favorable agreement with previous works. By using the quasi-harmonic Debye model, the thermodynamic properties including the Debye temperature QD, heat capacity CV, thermal expansion coeffi cient a, and Grüneisen parameter g were successfully obtained in the temperature range from 0 to 1 000 K and pressure range from 0 to 80 GPa, respectively. The optical properties including dielectric function e(v), absorption coeffi cient a(v), refl ectivity coeffi cient R(v), and refractive index n(v) were also calculated and analyzed.
基金Funded by the Fund for Talents of Yunnan Province,China(No.KKSY201403006)the National Natural Science Foundation of China(No.61564005)
文摘Structural, anisotropic, and thermodynamic properties of Imm2-BCN were studied based on density function theory with the ultrasoft psedopotential scheme in the frame of the generalized gradient approximation(GGA). The elastic constants were confirmed that the predicted Imm2-BCN is mechanically stable. The anisotropy of elastic properties were also studied systematically. The anisotropy studies of Young's modulus, shear modulus, linear compressibility, and Poisson's ratio show that the Imm2-BCN exhibits a large anisotropy. Through the quasi-harmonic Debye model, the relations between the equilibrium volume V, thermal expansion α, the heat capacity C_V and CP, the Grüneisen parameter γ, and the Debye temperature Θ_D with pressure P and temperature T were also studied systematically.
文摘We investigate the magnetic properties of Co-doped Cu_2O. We studied first the electronic and structural properties of Cu_2O using the optimization of the lattice constant which is 4.18 . The calculated gap is found between 0.825 eV and1.5 eV, these values are in good agreement with the experimental results. The Co atoms are inserted in Cu_2O by means of the density functional theory(DFT) using LSDA, LSDA +U, and LSDA + MBJ approximations in the WIEN2 k code, based on the supercell model by setting up 12, 24, and 48 atoms in(1×1 × 2),(1 × 2 × 2), and(2 × 2×2) supercells respectively with one or two copper atoms being replaced by cobalt atoms. The energy difference between the ferromagnetic and antiferromagnetic coupling of the spins located on the substitute Co has been calculated in order to obtain better insight into the magnetic exchange coupling for this particular compound. The studied compound exhibits stable integer magnetic moments of 2 μBand 4 μBwhen it is doped with 2 atoms of Co. Optical properties have also been worked out. The results obtained in this study demonstrate the importance of the magnetic effect in Cu_2O.
文摘Sweet potatoes have become a research focus in recent years, due to their particular nutritional and functional qualities. Considering yoghurt is one of the most popular dairy products, sweet potato supplementation will play a significant impact on the produced yoghurt texture it will also add attractive orange colour to the final product. The article focused on the replacement of the stabilizers used in the manufacture of yoghurt with sweet potato flour dehydrated in a lab (SPFL) due to its functional features and a less expensive alternative and the improvement of yoghurt colour due to the presence of anthocyanin pigment. In order to reach these goals, experimental yoghurt was fortified with 0, 0.5, 1, 2, and 4 g SPFL/100g cow milk (%) and stored at 4°C for 14 days. The obtained data were then compared with commercial yoghurt samples (CS1, CS2, CS3, and CS4). Sensory evaluation revealed that the 2% SPFL, CS1, and CS3 obtained higher scores than the other treatments. The fat content of the yoghurts was identical whereas, the other physicochemical parameters and water holding capacity (WHC %) levels varied. SPFL supplementation had a significant impact on the rheological properties of yoghurt production, allowing sweet potato flour to replace the industrial stabiliser. Scanning Electron Micrograph (SEM) of yoghurt enriched with SPFL revealed denser and smaller gaps, as well as the presence of sweet potato globules embedded in and attached to the gel matrix. The results obtained in the present research imply that sweet potatoes can be used to produce a kind of cohesive and gummy yoghurt that can be used instead of industrial stabilizers.