Purification and antioxidant capacity analysis of anthocyanin glucoside cinnamic ester isomers from Solanum nigrum fruits

In a recent study, anthocyanins, which have a strong free radical‐scavenging activity, were examined for their potential to effectively prevent cancer. However, clinical trials are limited by the purity of the anthocyanin. Multiple methods are used to extract and purify anthocyanins. Based on previous work on Solanum nigrum, which is a widely distributed plant, in this study, DM130 macroporous resin, Sephadex LH20, and a C18 column were used to separate cis–trans anthocyanin isomers. These anthocyanins constitute the majority of total S. nigrum anthocyanins. The results showed that this “DM130‐LH20‐C18 system” can be used to obtain a cinnamic acid‐derived cis–trans anthocyanin, petunidin‐3‐(p‐coumaroyl)‐rutinoside‐5‐glucoside, with a purity of 98.5%, for effective quantitation. In order to determine the antioxidant ability of the petunidin‐3‐(p‐coumaroyl)‐rutinoside‐5‐glucoside cis–trans isomers, three ordinary methods were adopted. The maximum antioxidant ability of the cis–trans anthocyanin was dozens of times higher than that of vitamin C.     

Coupled Electrical Conduction in Coordination Polymers: From Electrons/Ions to Mixed Charge Carriers

The coupled transport of ions and electrons is of great potential for next‐generation sensors, energy storage and conversion devices, optoelectronics, etc. Coordination polymers (CPs) intrinsically have both transport pathways for electrons and ions, however, the practical conductivities are usually low. In recent years, significant advances have been made in electronic or ionic conductive coordination polymers, which also results in progress in mixed ionic‐electronic conductive coordination polymers. Here we start from electronic and ionic conductive CPs to mixed ionic‐electronic conductive CPs. Recent advances in the design of mixed ionic‐electronic conductive CPs are summarized. In addition, devices based on mixed conduction are selected.     

Calibration of DC Potential Drop Method Considering Fatigue Load

Experimental Mechanics - The direct current potential drop (DCPD) method is an important method for monitoring crack initiation and propagation in specimens. During fatigue crack growth monitoring,...     

Skin Friction Reduction of Hypersonic Body by Supersonic Layer

Fluid Dynamics - Both numerical methods and wind tunnel tests were used to reduce skin friction for a hypersonic body. A hypersonic cone was tested under three different free-stream flow...     

Numerical and Experimental Investigation of Liquid Residue in 90° Bend Microchannel Based on Gas–Liquid Two-Phase Flow

The microfluidic chip for nucleic acid detection in vitro is an essential application of microfluidic technology to the process of in vitro diagnosis. The 90° bend microchannels in chip designed for facilitating assay reagent delivery may cause reagent residues and cast mutual contamination between detection reagents, which significantly affects the detection accuracy. In this paper, a two-dimensional gas–liquid two-phase flow model is constructed to simulate the liquid residue phenomenon. Using the results of simulation, the residual liquid generation can be observed and the area of residual liquid can be obtained. The accuracy of the numerical simulation is verified by comparison with the experimental results. The effects of the fillet radius R, the diameter ratio d₁/d₂ of the vertical to horizontal sections, the flow velocity v, and the surface roughness R_a on the residual amount are studied. We find that the fillet radius is inversely proportional to the residual amount within the range v = 20–100 mm/s and there is almost no liquid residue in the channel when the radius increases to R = 1 mm. When the channel diameter ratio d₁/d₂ increases, the liquid residual amount also increases by approximately 98%. The increased surface roughness R_a significantly increases the residual amount. The results of this study provide a reference for the optimal design of microchannels on chips.

     

Hybrid-triggered control for fuzzy Markov jump systems under input saturation

Nonlinear Dynamics - This article investigates the issue of hybrid-triggered control for fuzzy Markov jump system under input saturation. First, a hybrid-triggered control scheme is presented,...     

On the position of the upper limit temperature of homogeneous nucleation of precipitates in low concentrated Al?Zn alloys

The upper limit temperature T_hn of the onset of homogeneous nucleation of Guinier-Preston (GP) zones was determined for three Al Zn alloys with xZn = 4.5, 6.0 and 8.0 at.% by SAXS investigations (cooling from the range of homogeneity to various temperatures T_a and ageing at T_a). The results are T_hn = (95 ± 3) °C for xZn = 4.5 at.%, (118 ± 3) °C (6.0 at.%) and (154 ± 3) °C (8.0 at.%), respectively. The obtained results fit well the data known for the alloys with higher contents of Zn. It is stressed that one has to distinguish between T_hn, determined by isothermal measurements after a direct quench or cooling to the respective T_a, and the upper limit temperature T_rhn of the onset of the rapid homogeneous nucleation of GP zones (continuous cooling).     

一种新型双参量光纤布喇格光栅传感器的研制

介绍了一种新型的具有双参量测量功能的光纤布喇格光栅传感器.该传感器采用了特殊的结构,安装了两个不同中心波长的光纤布喇格光栅,可以实现两曲面之间狭小间隙的微小位移和温度的同时测量.实验表明,该传感器结构紧凑、体积小,具有良好的重复性和稳定性,位移测量误差不超过±10 μm,温度测量误差不超过±2℃.     

Structure-mechanics statistical learning uncovers mechanical relay in proteins

A protein''s adaptive response to its substrates is one of the key questions driving molecular physics and physical chemistry. This work employs the recently developed structure-mechanics statistical learning method to establish a mechanical perspective. Specifically, by mapping all-atom molecular dynamics simulations onto the spring parameters of a backbone-side-chain elastic network model, the chemical moiety specific force constants (or mechanical rigidity) are used to assemble the rigidity graph, which is the matrix of inter-residue coupling strength. Using the S1A protease and the PDZ3 signaling domain as examples, chains of spatially contiguous residues are found to exhibit prominent changes in their mechanical rigidity upon substrate binding or dissociation. Such a mechanical-relay picture thus provides a mechanistic underpinning for conformational changes, long-range communication, and inter-domain allostery in both proteins, where the responsive mechanical hotspots are mostly residues having important biological functions or significant mutation sensitivity.

Protein residues exhibit specific routes of mechanical relay as the adaptive responses to substrate binding or dissociation. On such physically contiguous connections, residues experience prominent changes in their coupling strengths.     

Interpenetrating polymer networks from polyurethanes and methacrylate polymers. I. Effect of molecular weight of polyols and NCO/OH ratio of urethane prepolymers on properties and morphology of IPNs

Two types of reinforced elastomeric interpentrating polymer network (IPN) were prepared by simultaneous polymerization and crosslinking in solution. The first type consisted of polyurethane-poly(methyl methacrylate) (PU/PMMA), and the second, of polyurethane-poly(methyl methacrylate-methacrylic acid) PU/P(MMA–MAA) of constant composition (90/10) and (80/20) by weight, respectively. The members of each type differed in the NCO/OH ratio of the PU prepolymer and the molecular weight (MW) of the polyol in the PU component because we wished to investigate systematically the effect of changing the NCO/OH ratio and MW of the polyol on the mechanical properties and morphology of the resulting IPNs. The mechanical properties, particularly the modulus of both tyes of IPN, increased with increasing NCO/OH ratio and decreased with increasing MW of the polyol in the PU. The morphology of the IPNs was studied by differential scanning calorimetry (DSC) and scanning electron microscopy (SEM). Improved phase compatibility and decreasing extent of phase separation was observed in both types of IPN with increasing NCO/OH ratio and decreasing MW of the polyol used in the PU. These results may imply that improved interpenetration results from increasing the NCO/OH ratio and decreasing the MW of the polyol in the PU component. The fact that the effect is more pronounced with the type of PU-P(MMA–MAA) IPN can be rationalized as due to the additional hydrogen bonding between the carbonyl in the carboxyl groups and the urethane or urea groups in the PU component.