Chunfa Dong’s research while affiliated with Hubei Polytechnic University and other places

The objective of this paper is to present the fractional Hadamard and Fejér-Hadamard inequalities in generalized forms. By employing a generalized fractional integral operator containing extended generalized Mittag-Leffler function involving a monotone increasing function, we generalize the well known fractional Hadamard and Fejér-Hadamard inequalities for m-convex functions. Also we study the error bounds of these generalized inequalities. In connection with some published results from presented inequalities are obtained.

The high strength bridge steel was processed with the simulated coarse grain heat affected zone (CGHAZ) thermal cycle with heat input varying from 30 to 60 kJ/cm, the microstructures were investigated by means of optical microscope (OM), scanning electron microscope (SEM), electron backscattering diffraction (EBSD) and transmission electron microscope (TEM), and the impact properties were evaluated from the welding thermal cycle treated samples. The results indicate that the microstructure is primarily composed of lath bainite. With decreasing heat input, both bainite packet and block are significantly refined, and the toughness has an increasing tendency due to the grain refinement. The fracture surfaces all present cleavage or fracture for the samples with different heat inputs. Moreover, the average cleavage facet size for the CGHAZ is nearly equal to the average bainite packet size and the bainitic packet boundary can strongly impede the crack propagation, indicating that the bainitic packet is the most effective unit in control of impact toughness in the simulated CGHAZ of high strength bridge steel.

A facile process was present in this paper for synthesizing nano silver particles colloidal in aqueous solutions using silver nitrate, sodium laurate, and hydrazine hydrate as silver precursor, stabilizer, and reducing agents, respectively. The generation of nano silver particles was confirmed by change of color from milk white to brown or dark. The prepared silver nanoparticles were analyzed by scanning electron microscope (SEM), transmission electron microscope (TEM), UV–Visible spectroscopy (UV–Vis), X-ray diffraction (XRD), and Fourier transform infrared spectroscopic (FT-IR). The SEM and TEM images indicated that the prepared silver nanoparticles have spherical shape, average size of 6 nm, and with a narrow distribution from 2 to 8 nm. The XRD information exhibited that the obtained metallic nanoparticles were highly crystalline in nature. FT-IR data demonstrated that the sodium laurate absorbed on the surface of silver nanoparticles. The effects of the sodium laurate and hydrazine hydrate on the silver nanoparticle formation were studied. The mechanism of the formation silver nanoparticles was discussed. The process raised in this study can be considered as an excellent candidate for the preparation of silver nanoparticles in a large-scale production. The simple method can be extended to synthesis of other noble metal nanoparticles.

A simple, straightforward and eco-friendly approach for synthesis of well dispersed nano gold particles was reported. In the process, Ginkgo Biloba leaf extract was used as both reducing and stabilizing agent without addition of any other reducing and capping agent. The characterization and properties of prepared gold nanoparticles were measured by transmission electron microscopy (TEM), Scanning electron microscope (SEM), energy dispersive X-ray spectroscopy (EDS), dynamic light scattering (DLS), powder X-ray diffraction (XRD), Fourier transform infrared (FT-IR) and UV-visible absorption spectroscopy (UV-vis). The formation of gold nanoparticles was confirmed by change of color from light yellow to red, which was further proved by absorbance peak at 544.5 nm in UV–vis spectroscopy. The particles were highly crystalline in nature, global in shape and small in size with a narrowly distribution from 10 nm to 40 nm. The gold nanoparticles were capped with extracts, preventing them from oxidation and agglomeration. The effect of reaction temperature, reaction time, amount of extracts and chloroauric acid solution was also investigated. The results reveal that these parameters play important roles in the formation of gold nanoparticles. The method exhibited in this study provides a very prospective process to prepare other noble nanoparticles, such as Pd, using renewable and environmentally materials.

A green, simple and low cost process for production of well dispersed, small size silver nanoparticles with narrow distribution from 3 nm to 15 nm was described. In this method, silver nanoparticles were prepared in aqueous medium by employing wolfberry fruit extract as both reducing and stabilizing agent without utilizing any other capping and reducing agent. The generation of metallic nanoparticles was observed by change of color and the UV–vis absorption spectroscopy. The obtained silver nanoparticles were analyzed by transmission electron microscopy (TEM) and X-ray diffraction (XRD). The results show that the as-synthesized silver nanoparticles are highly crystalline in nature, spherical in shape. The reaction times, silver nitrate concentrations and wolfberry fruit extract amounts play crucial roles in the synthesis of small silver nanoparticles. The method displayed in this paper offers a very hopeful mean to prepare other noble nanoparticles using renewable materials as reducing and capping agent.

A practical and convenient method for the synthesis of highly stable and small sized silver nanoparticles with narrow distribution from 3 nm to 15 nm is reported. Silver nitrate, stearic acid and hydrazine hydrate, were used as silver precursor, capping agents and reducing agents respectively. The formation of silver nanoparticles was observed by the change of color from milky white to dark red. The silver nanoparticles were characterized by transmission electron microscopy (TEM), UV–visible spectroscopy (UV–vis) and X-ray diffraction (XRD). The results demonstrated that the obtained metallic nanoparticles were single crystalline silver nanoparticles. The effects of the reaction temperature, the amount of stearic acid and ammonia on the particle size were investigated. The obtained silver nanoparticles are stable and will possibly be used in electronic applications. The preparation method is simple and may be extended to other noble metal for other technological applications.

A practical, convenient and green method for the synthesis of highly stable and small sized silver nanoparticles with narrow distribution from 2 nm to 30 nm is reported. Silver nitrate was used as silver precursor, and Osmanthus fragrans extract was acted as capping agent as well as reducing agent. The formation of silver nanoparticles was observed by the change of color from colorless to yellow. The as-prepared silver nanoparticles were characterized by scanning electron microscope (SEM), transmission electron microscopy (TEM), high resolution transmission electron microscopic (HRTEM), UV-visible spectroscopy (UV-vis), X-ray diffraction (XRD) and Fourier transform infra-red spectroscopic (FT-IR). The formation of silver nanoparticles was confirmed by its characteristic surface plasmon absorption peak at 400–450 nm in UV–vis spectra. The TEM and SEM images showed that the as-synthesized silver fine spherical particles are distributed uniformly with a narrow distribution from 2 nm to 30 nm. The HRTEM and XRD results demonstrated that the obtained metallic nanoparticles were single crystalline silver nanoparticles. FT-IR data revealed that the silver nanoparticles are coated with Osmanthus fragrans extract. The effects of the silver nitrate and Osmanthus fragrans extract concentrations on the particle size were investigated. The green synthesis method is simple and may be extended to preparation of other noble metal nanoparticles.

In this paper, the thermal field of double wire welding is simulated by using ANSYS software. Simulation results were shown that the total heat input (E) is the most significant parameters to change the value of t8/5; By the mean of rationally controlling the proportion of the front arc heat input (E1) in the total heat input (E) and appropriately selecting double wire spacing (L), It is effective means to get the double wire welding thermal cycle. By the way of simulation, it is possible to manage the thermal input in the double welding wires and to control the temperature field and cooling rate that are fundamental for the final joint quality, it is great importance guidance to optimize the double wire welding process parameters.

Electrical discharge machining removes electrically conductive material by means of rapid and repetitive spark discharges resulting from local explosion of a dielectric liquid. The electrical discharge machining has been widely used for cutting fine blanking tools which are made of especially hard tool steels. Whereas, its thermal nature causes great concerns regarding surface integrity, which matters a lot to tool life. In the present study, the evolution of surface integrity of the S390 and SKD11 with multi-cutting is comprehensively compared. The result shows that the surface roughness, white layer thickness and surface residual stress decrease with the increase of cutting pass. Compared to the finish trim cut surface of S390 sample, more pinholes and slightly larger craters were produced and the micro cracks could be found on the finish trim cut surface of SKD11 sample.

Silver nanoparticle (Ag-np) is a new kind of antibacterial agent which is widely used in medical supplies. In this study, a simple approach is described to obtain Ag-doped HA scaffolds. Hydroxyapatite (HA) bone scaffolds with controllable pore size were fabricated by a micro-syringe extrusion system. Sintered HA scaffolds were then immersed in silver reaction hydrosol in order to get Ag-doped HA scaffolds. SEM and EDS shows a uniform distribution of silver nanoparticles on the surface of HA scaffolds. Such Ag-np doped HA scaffolds, displaying a good antibacterial activity against Escherichia coli (E. coli), are likely to prevent bone implant associated bacterial infections.