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The C-S activation and sulfur removal from native thiols is challenging, which limits their application as feedstock materials in organic synthesis despite their natural abundance. Herein, we introduce a per-/polyfluoroaryl moiety, which serves as a redox-active scaffold, into sp

Aspartic protease emerges as an optimistic hydrolytic agent to obtain several protein hydrolysates. An aspartic protease gene from Aspergillus fumigatus Af293 was successfully expressed in Pichia pastoris (GS115) and its hydrolytic potentials on silkworm (Bombyx mori) pupae protein were determined. It was optimum at pH 4.0 and 50 °C and stable over pH range 4.0-5.0 and temperatures 45-55 °C with a specific activity of 8408.9 ± 305.6 U/mg. SDS-PAGE analysis revealed the molecular weight of the recombinant protease to be 45 kDa. The half-life (t1/2) of the recombinant protease at 40, 50, 60, and 70 °C was 30, 25, 35, and 20 min, respectively. The protease showed enhanced activity in the presence of Cu2+, Pb2+ and SDS. Its substrate specificity studies were revealed in the order of cleaving ability to Bovine Serum Albumin (BSA) > Silkworm pupae powder (SPP) > Casein > Casein sodium salt (CSS). Upon hydrolysis of silkworm pupae protein, it showed enhanced and plausible hydrolytic potentials, increasing the degree of hydrolysis to 50 ± 6.1% at 6 h, increased solubility by 80%, and improved functional properties. The stable characteristics and hydrolytic performance of the recombinant aspartic protease qualify it for industrial application, especially within the food and related industries.

The C−S activation and sulfur removal from native thiols is challenging and limits the application of thiols as typical feedstock materials in organic synthesis despite their natural abundance. Herein, we describe a simple procedure to introduce a per-/polyfluoroaryl moiety, which serves as a redox-active scaffold, into alkyl/aryl thiols using nucleophilic aromatic substitution (SNAr) chemistry to activate the C−S bond. The per-/polyfluoroaryl group acts as an electron acceptor in single electron transfer events to generate radical intermediates through cleavage of the C−S bond of mercaptans and utilize them in nickel-catalyzed reductive cross-coupling reactions. In addition, using computational methods, we shed light on the mechanism of this class of SNAr reaction and show that the preference for a concerted or stepwise mechanistic pathway can be easily rationalized through a Marcus-type argument, as well as consideration of the relative stability of the potential energy surfaces.

Objective To investigate the cause and relevant factors of retraction of transporting bone segment (TBS) after removal of its fixator during Ilizarov bone transport. Methods The clinical data of 37 cases with tibial bone defect treated by Ilizarov bone transport, in whom the TBSs were removed before mature of mineralization of the distraction callus and union of the docking site, were analyzed retrospectively. Bivariate correlation was used to analyze relationship between retraction distance of TBS and age, gender, disease course, length of bone defect, times of pre-operation, size of TBS, transport distance, cause of removal, timing and time interval of removal of TBS fixator. Risk factors with significant level were further identified using multivariate linear regression. Results Bivariate correlation analysis showed that the timing of removal was negatively correlated with the retraction distance, the time interval, cause of removal, transport distance and size of TBS were positively correlated with the transport distance(all p0.05). Multivariate linear regression analysis of the 5 risk factors showed that the timing of removal, transport distance and cause of removal were independent risk factors for the retraction distance (p0.05). Conclusion The TBS is subjected to distraction force from all the adherent soft tissues during Ilizarov bone transport, which has elastic properties and can make a retraction of TBS if its fixator is removed before mature of mineralization of the distraction callus and union of the docking site. The retraction distance is related to the TBS size, transport distance, timing and time interval of removal of TBS fixator. Importantly, the timing of removal and transport distance are the main factors for the retraction, especially the timing of removal had the greatest impact.

It is well known that the flow field over a delta wing is dominated by a pair of counter rotating leading edge vortices (LEV). However, their mechanism is not well understood. The flow visualization technique is a promising non-intrusive method to illustrate the complex flow field spatially and temporally. A basic flow visualization setup consists of a high-powered laser and optic lenses to generate the laser sheet, a camera, a tracer particle generator, and a data processor. The wind tunnel setup, the specifications of devices involved, and the corresponding parameter settings are dependent on the flow features to be obtained. Normal smoke wire flow visualization uses a smoke wire to demonstrate the flow streaklines. However, the performance of this method is limited by poor spatial resolution when it is conducted in a complex flow field. Therefore, an improved smoke flow visualization technique has been developed. This technique illustrates the large-scale global LEV flow field and the small-scale shear layer flow structure at the same time, providing a valuable reference for later detailed particle image velocimetry (PIV) measurement. In this paper, the application of the improved smoke flow visualization and PIV measurement to study the unsteady flow phenomena over a delta wing is demonstrated. The procedure and cautions for conducting the experiment are listed, including wind tunnel setup, data acquisition, and data processing. The representative results show that these two flow visualization methods are effective techniques for investigating the three-dimensional flow field qualitatively and quantitatively.

The present study was undertaken to evaluate the degradation performance of 4-chlorophenol (4-CP) using TiO 2 /WO 3 and TiO 2 /SnO 2 systems. A BET surface area analyzer, UV–vis spectroscopy, scanning electron microscopy (SEM), X-ray diffraction (XRD) and electron spectroscopy for chemical analysis (ESCA) were employed to characterize the photocatalyst. The band edge wavelength increased to 475 nm and gap energy decreased to 2.61 eV in the TiO 2 /WO 3 system as compare to the single TiO 2 . Although the specific surfaces area of TiO 2 /WO 3 decreases due to its larger size as compared to either TiO 2 or WO 3 , the 4-CP degradation efficiency significantly increased as compared to single TiO 2 or WO 3 system at 435 nm wavelength. The TiO 2 /WO 3 degradation of 4-CP at 369 nm was in fact inhibited. For TiO 2 /SnO 2 , the degradation efficiency also suffered at 369 nm, and only slightly increased compared to otherwise hardly 4-CP degraded in single TiO 2 or SnO 2 system. Since there is a significant accumulation of byproducts, the buildup of these intermediates on the catalyst surface may be responsible for their poor performance.