Directed Evolution of a Cp*RhIII-Linked Biohybrid Catalyst Based on a Screening Platform with Affinity Purification

Directed evolution of Cp*Rh^III-linked nitrobindin (NB), a biohybrid catalyst, was performed based on an in vitro screening approach. A key aspect of this effort was the establishment of a high-throughput screening (HTS) platform that involves an affinity purification step employing a starch-agarose resin for a maltose binding protein (MBP) tag. The HTS platform enables efficient preparation of the purified MBP-tagged biohybrid catalysts in a 96-well format and eliminates background influence of the host E. coli cells. Three rounds of directed evolution and screening of more than 4000 clones yielded a Cp*Rh^III-linked NB(T98H/L100K/K127E) variant with a 4.9-fold enhanced activity for the cycloaddition of acetophenone oximes with alkynes. It is confirmed that this HTS platform for directed evolution provides an efficient strategy for generating highly active biohybrid catalysts incorporating a synthetic metal cofactor.     

Electron Holography Studies on Narrow Magnetic Domain Walls Observed in a Heusler Alloy Ni50Mn25Al12.5Ga12.5

Peculiar magnetic domain walls produced in Heusler alloys, which have attracted renewed interest due to their potential application to actuators and spintronic devices, are studied here using electron holography. The observations reveal unexpectedly narrow magnetic domain walls, the width of which showed perfect agreement with that of the antiphase boundaries (APB, e.g., only 3 nm). While the results can be explained by the significant depression of ferromagnetism due to the local chemical disorder, the electron phase shift indicates that ferromagnetic correlation still remains in the APB region.     

Hydrophobic Tagged Dihydrofolate Reductase for Creating Misfolded Glycoprotein Mimetics

In the endoplasmic reticulum (ER), nascent glycoproteins that have not acquired the native conformation are either repaired or sorted for degradation by specific quality‐control systems composed by various proteins. Among them, UDP‐glucose:glycoprotein glucosyltransferase (UGGT) serves as a folding sensor in the ER. However, the molecular mechanism of its recognition remains obscure. This study used pseudo‐misfolded glycoproteins, comprising a modified dihydrofolate reductase with artificial pyrene–cysteine moiety on the protein surface (pDHFR) and Man₉GlcNAc₂‐methotrexate (M9‐MTX). All five M9‐MTX/pDHFR complexes, with a pyrene group at different positions, were found to be good substrates of UGGT, irrespective of the site of pyrene modification. These results suggest UGGT's mode of substrate recognition is fuzzy, thus allowing various glycoproteins to be accommodated in the folding cycle.     

Predictive Simulation of Deformation and Failure of Peat-Calcareous Soil Layered Ground Due to Multistage Test Embankment Loading

The continuous behaviour of a ground-embankment system from the stage of deformation up to failure was predicted with respect to an actual test embankment that had been constructed in stages on a soft ground made up of peat and calcareous soil. The behaviour prediction was carried out by employing soil-water coupled finite deformation analysis, which also included simulation of the embankment construction process. The information used in the analysis was limited to such things as the results of soil tests on soil materials (peat and calcareous soil) sampled from the ground, including their sensitivity ratios, and the embankment's construction history. The SYS Cam-clay model was used in the constitutive equations of the soils to determine the material constants of the soils and the initial conditions of the ground, and the computations were performed under plane strain conditions. As a result, the computed profiles of W-type ground settlement and of slip surfaces running through the embankment were found to be in good overall agreement with the actual profiles measured at the site. Furthermore, we found that this slippage is attributable to the undrained shear response of the soil elements in the calcareous soil layer, where slippage begins to occur during embankment loading. In other words, the slippage is caused by the rapid softening behaviour caused by the degradation of structure after the effective stress ratio reaches the vicinity of the critical state line.     

含黏粒砂土场地液化离心机振动台试验研究

提出了含黏粒砂土模型地基制备、饱和与均匀性监测技术,利用ZJU-400土工离心机振动台开展了相同相对密度含黏粒砂土（黏粒含量10%）和洁净砂的地震液化模型试验,再现了水平场地地震液化现象,揭示了含黏粒砂土场地液化灾变特点。弯曲元波速监测表明,模型制备均匀性良好,相同条件下含黏粒砂土剪切波速比洁净砂低。而根据超静孔压消散与固结沉降观测分析发现,含黏粒砂土渗透系数比洁净砂低一个数量级,从而影响其液化前后超静孔压响应和应力应变行为。渗透性差异导致模型内超静孔压产生模式和消散速率显著不同,振动时含黏粒砂土模型浅层超静孔压累积比洁净砂慢,而深层则相反;震后含黏粒砂土孔压消散时间是洁净砂的15倍。液化过程中含黏粒砂土剪应力应变响应比相同深度处的洁净砂更显著,液化后其滞回圈应变较大、割线模量较小且阻尼比较大。土体液化沉降主要发生在液化后超静孔压消散过程,含黏粒砂土模型超静孔压消散时间更长,沉降量更大。上述成果为进一步研究含黏粒砂土地震响应分析及其液化判别提供了科学依据。     

Separation of C6H6 and C6H12 from H2 using ionic liquid/PVDF composite membrane

Ionic liquid/polyvinylidene fluoride composite membrane was successfully prepared by impregnation method and used for the separation on organic chemical hydride process. The separation factors of C₆H₆/H₂ and C₆H₁₂/H₂ in the ternary mixture system were 7500 and 300, respectively. The ionic liquid membrane showed an excellent possibility as a technology of H₂ purification in the organic chemical hydride process by removing aromatic hydrocarbon and cycloalkane simultaneously from the ternary system. © 2015 American Institute of Chemical Engineers AIChE J, 62: 624–628, 2016     

Influence of swelling of noncrystalline regions in silk fibers on modification with methacrylamide

The degrees of swelling of noncrystalline regions of domestic and tussah silk fibers were investigated by measuring the small-angle X-ray scattering intensity of the fibers in wet conditions and analyzing the scattering intensity based on a two-phase model, i.e., crystalline regions and water-swollen noncrystalline regions. The influence of the degree of swelling of noncrystalline regions on the graft treatment of these fibers with methacrylamide was investigated. The changes in the structure caused by the graft treatment were also analyzed using the wide-angle X-ray diffraction measurements. As compared with the tussah silk fibers, the domestic silk fibers showed a larger degree of swelling of the noncrystalline regions, and gained a larger amount of resin by the graft treatment. The crystallites with smaller sizes in the tussah silk fibers were destroyed preferentially by the graft treatment. For the domestic silk fibers, the crystallites were destroyed more seriously and rather homogeneously independent of the crystallite sizes. © 1996 John Wiley & Sons, Inc.     

Mechanism of enhanced impact strength of poly(vinyl chloride) modified by acrylic graft copolymer

The mechanism of enhanced PVC impact strength of poly(vinyl chloride) modified by an acrylic graft copolymer was studied by the three-point bending test on a U-notched bar. In the mechanism, the void formation from the modifier released the constrained strain. The release suppresses the stress below the fibril strength in the material; consequently, stable deformation can develop over a large area and, thus, the impact strength of PVC modified by the acrylic graft copolymer is improved. © 1996 John Wiley & Sons, Inc.