Formation of corn fiber gum-milk protein conjugates and their molecular characterization

Corn fiber arabinoxylan is hemicellulose B isolated from the fibrous portions (pericarp, tip cap, and endosperm cell wall fractions) of corn kernels and is commonly referred to as corn fiber gum (CFG). Our previous studies showed that CFG isolated from corn bran (a byproduct of corn dry milling) contains very little protein and is an inferior emulsifier for oil-in-water emulsion systems as compared to corn fiber gum isolated from corn fiber derived from the corn wet-milling process. The protein deficient CFG isolated from corn bran was covalently conjugated with byproducts of cheese processing, β-lactoglobulin (β-LG) and whey protein isolate (WPI) using an economical food-grade Maillard-type heating reaction for the purpose of increasing their commercialization potential as a food emulsifier and soluble nutritional additive in beverages. The formation of the CFG-protein conjugates has been confirmed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). It has also been demonstrated that CFG-protein conjugates are capable of producing fine emulsions with better stability than either CFG or protein alone. The molecular characterization of CFG-protein conjugates was performed by high-performance size-exclusion chromatography (HPSEC) coupled to on-line multi-angle laser light scattering and viscometric detection. The analysis by HPSEC revealed that CFG-protein conjugates had higher weight-average molar mass (M_w, 340-359 kDa) and polydispersity (M_w/M_n, 1.74) than the corresponding unconjugated CFG (M_w, 290 kDa and M_w/M_n, 1.35). The z-average root-mean-square radius of gyration (R_gz) of CFG-protein conjugates was slightly higher (30.5-33.5 nm) in comparison to CFG (29.5 nm) but their weight-average-intrinsic viscosity (η) remained unchanged (about 1.32 dL g⁻¹). The Mark-Houwink exponent “a” of conjugates (0.40) was lower than the unconjugated CFG (0.53) indicating the formation of a more compact structure after conjugation with protein. These findings should benefit the beverage industry, which can use this information to produce a high quality emulsifier from the low-value byproducts of corn dry milling and cheese processing.     

Effects of raw material homogenization on the structure of basalt melt and performance of fibers

In this study, basalt from a base in Hebei, China, was selected as the raw material. Water-quenched basalt glasses and basalt fibers were prepared at different homogenization times and temperatures. The water-quenched glass structure was characterized by XRD and a Raman spectrometer followed by fitting of their Raman spectra by Gaussian curves to obtain information about melt structure. The fiber performance was characterized by fiber strength meter and fiber fineness meter. The results demonstrate that homogenization time and temperature had significant effects on the structure of basalt melt. The degree of polymerization of the melt increased with increasing homogenization time and decreased with increasing homogenization temperature. The fiber strength increased with increasing the degree of polymerization. As the homogenization time and temperature increased, coefficients of variation of fiber strength and fiber diameter decreased, indicating enhanced fiber stability.     

聚烯烃重力掺混料仓及其评价

介绍了聚烯烃掺混料仓的常用形式和工作原理,并对5种常用掺混料仓的特点和性能进行了综合评价,提出了掺混料仓选用的原则。     

高Zn含量Al-Zn-Mg-Cu合金均匀化过程中显微结构演变研究

利用显微镜（OM）、差热分析（DSC）、扫描电镜（SEM）和X衍射（XRD）研究一种高Zn含量Al-Zn-Mg-Cu合金在均匀化处理过程中的显微结构演变,使用扩散动力学模型推导均匀化动力学方程,用于确认最佳均匀化参数。结果表明：合金的铸态组织中存在严重偏析,非平衡共晶结构包含α(Al)、Mg(Zn,Cu,Al)₂、 S(Al₂CuMg)、θ(Al₂Cu)和富Fe相。当前研究表明均匀化过程中没有发生Mg(Zn,Cu,Al)₂相向S(Al₂CuMg)相的转变,Mg(Zn,Cu,Al)₂相直接回溶。随着均匀化的进行,θ(Al₂Cu)相溶入基体。均匀化后富Fe相仍残留,但随着保温时间的延长,富Fe相中的Zn、Mg元素铸件减少或消失。最佳均匀化参数为440 oC×12 h 468 oC×24 h,这与均匀化动力学的分析相一致。     

7050铝合金均匀化热处理后的组织转变

利用金相组织观察、差示扫描量热法、扫描电镜、X射线衍射等手段对7050铝合金铸态组织、不同条件下的均匀化效果和均匀化前后的组织转变进行了分析。结果表明,7050合金半连续铸锭中存在大量具有η-MgZn2型晶体结构的非平衡第二相Mg(AlZnCu)2,其熔化温度为477℃,在均匀化处理过程中,该非平衡凝固共晶相在477℃向合金基体溶解并转变成Al2CuMg(S相),S相在该合金中的熔化温度为490℃;在460℃均匀化处理时,结晶相η全部消失,晶间和晶内均出现球状S相。在随后的冷却过程中η相和S相先后在晶内析出,但在260℃时S相再一次消失。     

滨海断鼻沙三段油气成藏特征

根据歧口凹陷滨海断鼻沙三段油气包裹体特征及地层埋藏史的恢复,确定了研究区油气成藏期次和成藏时间,认为沙三段油气以晚期成藏为主,其中Qs1井为多次非连续充注2期成藏（早期和晚期）。结合构造活动特征、生排烃演化史及油气运聚史对油气成藏史进行了分析,认为沙三段油气藏分布主要受生烃演化阶段与构造发育配置关系的控制,并形成了“高油低气”的分布特征,研究区沙三段是寻找大气田的有利区域。     

Neural networks as material models within a multiscale approach

This paper shows the application of neural networks in a multiscale analysis of a reinforced concrete beam. A mesoscale model is presented, which simulates the pullout test of a reinforcement bar in concrete. By applying a homogenization procedure, a macroscopic stress vs. crack opening response is obtained from the mesoscale simulations. The neural network is used to approximate this relation in a macroscale simulation and replaces the material formulation of the interface layer between concrete and reinforcement, thus avoiding the computationally expensive parallel simulation on different scales.     

Strain energy-based homogenization of nonlinear elastic particulate composites

The macroscopic constitutive law for a heterogeneous solid containing two dissimilar nonlinear elastic phases undergoing finite deformation is obtained. Attention is restricted to the case of spherical symmetry such that only the materials consisting of an irregular suspension of perfectly spherical particles experiencing all-round uniform loading are considered which leads to a one-dimensional modeling. For the homogenization procedure, a strain-energy based scheme which utilizes Hashin’s composite sphere is employed to obtain the macroscopic stress-deformation relation added by the initial volume fraction of the particles. As applications of the procedure, the closed-form macroscopic stress expression for a generalized Carroll composite material is derived. Then, by choosing carbon black-filled rubbers, unknown bulk modulus of the carbon black particles is calculated. Finally, the particle-reinforced flexible polyurethane foam is studied using the Ritz method. It is shown that the analytical outcome for composites filled by compressible inclusions is applicable for porous materials with the same matrix.     

波形碳纳米管增强复合材料的有效刚度和局部应力的宏微观均质化数值模拟

采用分子动力学方法简化的碳纳米管等效纤维模型,利用具有精确周期性边界条件的均质化理论和宏微观均质化法分析正弦波形非连续碳纳米管的有效刚度和局部应力分布规律.结果表明,纳米增强复合材料的有效刚度和局部应力对碳纳米管的波形非常敏感,碳纳米管稍有弯曲就会导致复合材料有效刚度降低和应力传递能力的下降,为揭示复合材料中碳纳米管的增强机制和改善增强效果提供理论依据.     

Some micromechanical models of elastoplastic behaviors of porous geomaterials

Some micromechanics-based constitutive models are presented in this study for porous geomaterials. These micro-macro mechanical models focus on the effect of porosity and the inclusions on the macroscopic elastoplastic behaviors of porous materials. In order to consider the effect of pores and the compressibility of the matrix, some macroscopic criteria are presented firstly for ductile porous medium having one population of pores with different types of matrix (von Mises, Green type, Mises–Schleicher and Drucker–Prager). Based on different homogenization techniques, these models are extended to the double porous materials with two populations of pores at different scales and a Drucker–Prager solid phase at the microscale. Based on these macroscopic criteria, complete constitutive models are formulated and implemented to describe the overall responses of typical porous geomaterials (sandstone, porous chalk and argillite). Comparisons between the numerical predictions and experimental data with different confining pressures or different mineralogical composites show the capabilities of these micromechanics-based models, which take into account the effects of microstructure on the macroscopic behavior and significantly improve the phenomenological ones.