Reentrant behavior of magnetic ordered phase in spin-crossover solids with quenched disordered ligand field

The Ising-like model of spin-crossover solid compounds with quenched random ligand field has been investigated by the mean-field (infinite-range) approximation. An exact solution for the problem is found within the replica formalism. The magnetic diagrams are obtained; the relations between the intermolecular coupling and the temperature as well as the reentrant phenomena of the magnetic ordered phase are discussed.     

Curing behavior and properties of high biosourced epoxy resin blends based on a triepoxy monomer and a tricarboxylic acid hardener from 10-undecenoic acid

Renewable propane-1,2,3-triyl tris(9-(oxiran-2-yl) nonanoate) (EGU, 100 wt% biogenic) and a tricarboxylic acid triglyceride (CGTU) hardener (85.7 wt% biogenic) were synthesized from 10-undecenoic acid (10-UDA) and used to produce epoxy resins with 52–92 wt% biobased carbon. CGTU was prepared by thermally activated thiol-ene coupling of thioglycolic acid onto propane-1,2,3-triyl tris(undec-10-enoate), (GUD) in the absence of solvent. The characterized CGTU was used as a green hardener of blends based on EGU and a conventional bisphenol A-based epoxy pre-polymer (DGEBA) at various mass percentages (0–100 wt%) with an stoichiometric epoxy/acid equivalent ratio. Calorimetric studies revealed higher peak temperature, lower reaction heats, and longer gelation times in resins with high EGU proportion, evidencing the lower reactivity of aliphatic EGU compared with aromatic DGEBA. Cured resins were yellowish transparent rubber-like materials with glass transition temperatures (Tg) varying from −14 °C to −42 °C and tensile strength in the range of 1750 kPa–790 kPa, for 0 and 100 wt % EGU, respectively. The soluble fraction of all resins was less than 4.3%, reflecting a high level of crosslinking. Thermosets with high biobased content showed both UV-light protection and visible light transparency.     

Δu-a(x)u+b(x)u~p=0奇解的渐近性质

讨论了半线性椭圆方程Δu-a(x)u+b(x)up=0奇解的渐近性质,其中u∶Ω→R,ΩRn,n 3,n/(n-2)相似文献   

Asymptotics of zeros of polynomials arising from rational integrals

We prove that the zeros of the polynomials Pm(a) of degree m, defined by Boros and Moll via

     

高校创新型科研团队行为模式研究——以生命科学部高校国家重点实验室为例

国家重点实验室作为高校创新型科研团队的"国家队",是我国基础研究的核心力量和重大创新成果的摇篮,更是培养高层次科技人才的基地.研究高校创新型科研团队组织分布、管理结构、团队成员组成、科研、学术交流等具体行为模式特征,将是进一步发展和完善高校创新型科研团队的有力切入点,也将为相关科研政策的改进和完善提供参考依据.     

Emergence of a non-Fowler-Nordheim-type behavior for a general planar tunneling barrier

In this work we investigate a generalized tunneling barrier for planar emitters at zero-temperature. We present the evidence of the emergence of a non-Fowler-Nordheim-type general behavior for the field emission current density in the case that the Fermi energy (μ) is comparable with or smaller that the decay width ($d_F$). Therefore, for some non-metals or materials that have very small Fermi energy the standard Fowler-Nordheim-type theory may require a correction. In the opposite regime, i.e., for μ much larger that $d_F$, we confirm that the conventional theory is suitable for metals.     

Thermal Dehydration and Vibrational Studies of ZnK4(P3O9)2 · 6H2O

The thermal dehydration of ZnK₄(P₃O₉)₂ · 6H₂O was studied in the range 25–500°C by thermogravimetric analysis (TGA and DSC) and X‐ray diffraction. We found, based on the TGA and DSC scans, the dehydration of this salt takes place in three stages with a loss of the six water molecules. The infrared and Raman spectra of ZnK₄(P₃O₉)₂ · 6H₂O have been recorded and interpreted using a factor group analysis. The internal modes are assigned in terms of POP and PO₂ structural units using experimental and theoretical IR and Raman frequencies.     

High-Temperature dispersion zones in cross-linked natural rubber

The complex dielectric constant of natural rubber samples cross-linked by sulfur and dicumyl peroxide has been measured over a frequency range from 1.5 to 3.0 × 10⁵ cps by the bridge method and from 3.0 to 1.0 × 10⁴ cps by the relaxation method. Two dispersion peaks were detected which lay in the measured frequency range at temperatures above the main dispersion zone. Temperature and cross-link density-dependent shift of these peaks were studied and compared with the results obtained by Ferry et al. from complex compliance measurements performed on analogous systems.     

Magnetocaloric effect and transition order of Mn5Ge3 ribbons

Single phase Mn₅Ge₃ ribbons were successfully synthesized by single roller melt-spinning method followed by an annealing procedure at 800 °C for 1 h. The magnetocaloric effect and transition order were investigated by dc magnetization measurement. A maximum entropy change of 4.92 J/kg K and a refrigerant capacity of 201.3 J/kg were observed at an external field change of 30 kOe. The Banerjee criterion was adopted to discriminate the order of the transition, indicating a second order transition. The calculated entropy changes were also obtained by Landau theory, which are in agreement with the experimental values at the temperature region above the Curie temperature. This phenomena implies a potential transition of the magnetic interaction in the vicinity of the Curie temperature. Universal behavior was also indicated in that all of the experimental entropy change curves collapse into one universal curve, which is consistent with the Banerjee criterion.