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Proper selection of bath additives is critical to the plating rate, phosphorus content and corrosion resistance of the nickel–phosphorus (Ni–P) alloy deposits. In this work, electroless Ni–P alloy deposition from an acidic bath using sodium hypophosphite as the reducing agent at relatively low temperatures (30°C and 60°C) was carried out in the presence and absence of urea additives. The effects of different concentrations of urea on plating rate and phosphorus content of the Ni–P deposits were studied. The results showed that the plating rate and the phosphorus content of the Ni–P deposits were largely dependent on the concentration of urea in the bath. The corrosion resistance of the Ni–P deposits was evaluated in aerated 3.5 wt.% sodium chloride (NaCl) solution using potentiodynamic polarization curves. It was found that the corrosion resistance of the deposits obtained from the bath solution containing 1 g/L of urea was the highest. In addition, cyclic voltammetry techniques were used to study the mechanism of electroless Ni–P alloy deposition in the bath. The results revealed that the addition of urea to the bath promoted the concentrations of adsorbed atomic hydrogen and sodium hypophosphite on mild steel surface, which markedly increased the phosphorus content of the Ni–P deposits. This work offers a new way that highlights the relation between the urea additives and phosphorus content. [ABSTRACT FROM AUTHOR]

The property theory is a unique principle instructing traditional Chinese doctors to prescribe proper medicines against diseases. As an essential part of it, the five-flavor theory catalogs various Chinese materia medicas (CMMs) into five flavors (sweet, bitter, sour, salty, and pungent) based on their taste and medical functions. Although CMM has been successfully applied in China for thousands of years, it is still a big challenge to interpret CMM flavor via modern biomarkers, further deepening its elusiveness. Herein, to identify the correlation between gut microbiota and CMM flavor, we selected 14 CMMs with different flavors to prepare their aqueous extracts, quantified the contained major chemical components, and then performed full-length 16S rRNA sequencing to analyze the gut microbiota of C57BL/6 mice administrated with CMM extracts. We found that flavones, alkaloids, and saponins were the richest components for sweet-, bitter-, and pungent-flavored CMMs, respectively. Medicines with merged flavors (bitter-pungent and sweet-pungent) displayed mixed profiles of components. According to gut microbial analysis, modulation of CMMs belonging to the same flavor on the taxonomic classification was inconsistent to an extent, while the functional sets of gut microbiota, co-abundance gene groups (CAGs), strongly and differentially responded to distinct flavors. Moreover, these correlations were in line with their pharmacological actions. Therefore, the gut microbial functional sets (CAGs) could act as the possible indicator to reflect CMM flavor, rather than the composition of microbial community. [ABSTRACT FROM AUTHOR]

The characteristics of flow fields for a complete evolution of the non-breaking solitary wave, having a wave-height to water-depth ratio of 0.363 and propagating over a 1:5 sloping bottom, are investigated experimentally. This study mainly focuses on the occurrences of both flow separation on the boundary layer under an adverse pressure gradient and subsequent hydraulic jump with the abrupt rising of free surface during rundown motion of the shoaling wave, together with emphasis on the evolution of vortex structures underlying the separated shear layer and hydraulic jump. A flow visualization technique with particle trajectory method and a high-speed particle image velocimetry (HSPIV) system with a high-speed digital camera were used. Based on the instantaneous flow images visualized and/or the ensemble-averaged velocity fields measured, the following interesting features, which are unknown up-to-date, are presented and discussed in this study: (1) Flow bifurcation occurring on both offshore and onshore sides of the explicit demarcation curve and the stagnation point during runup motion; (2) The dependence of the diffuser-like flow field, being changed from the supercritical flow in the shallower region to the subcritical flow in the deeper counterpart, on the Froude number during the early and middle stages of rundown motion; (3) The positions and times for the occurrences of the incipient flow separation and the sudden rising of free surface of the hydraulic jump; (4) The associated movement and evolution of vortex structures under the separated shear layer, the hydraulic jump and/or the high-speed external main stream of the retreated flow; and (5) The entrainment of air bubbles from the free surface into the external main stream of the retreated flow. [ABSTRACT FROM AUTHOR]

2 nanofibers and nanotubes were synthesized by electrospinning method. Magnetization measurement indicates that the 2 nanofibers and nanotubes annealed in air at 500°C exhibit the room-temperature ferromagnetism and the ferromagnetism of nanotubes is stronger than the nanofibers. Selected area electron diffraction, X-ray diffraction and Raman measurements show that all the samples possess a typical rutile structure and no other impurity phases are observed. The results of the Raman spectra also indicate that there are lots of defects existing in the fabricated samples. The observed room-temperature ferromagnetism in 2 nanofibers and nanotubes possibly originates from oxygen vacancies. The field cooled (FC) and zero-field-cooled (ZFC) magnetization curves indicate that the Curie temperature TC is above 300 K. SnO2 nanofibers and nanotubes were synthesized the electrospinning method. The observed room-temperature ferromagnetism originates from surface defects. [ABSTRACT FROM AUTHOR]

Taking account of ambipolar diffusion and drift in long-base silicon p+-n junctions under low-level injection conditions, a developed analytical model for the total drift field enhanced by the Dember field with different mobilities is presented in excellent agreement with numerical simulation results. Based on the results of theoretical analysis and numerical simulation, the entire current in the n-type quasineutral region is found to consist of minority-hole diffusion-component and majority-electron drift- and diffusion-component and the Dember field plays a dominant role in modulating the local drift field to balance all components above to keep the current continuity. Our analytical model provides a comprehensive interpretation of ambipolar current character to fully understand existing theories of semiconductor devices. [ABSTRACT FROM AUTHOR]