Yi-Nan Zhang

Experimental study of the Ca-Mg-Zn system using diffusion couples and key alloys

Abstract Nine diffusion couples and 32 key samples were prepared to map the phase diagram of the Ca–Mg–Zn system. Phase relations and solubility limits were determined for binary and ternary compounds using scanning electron microscopy, electron probe microanalysis and x-ray diffraction (XRD). The crystal structure of the ternary compounds was studied by XRD and electron backscatter diffraction. Four ternary intermetallic (IM) compounds were identified in this system: Ca3MgxZn15−x (4.6x12 at 335 °C, IM1), Ca14.5Mg15.8Zn69.7 (IM2), Ca2Mg5Zn13 (IM3) and Ca1.5Mg55.3Zn43.2 (IM4). Three binary compounds were found to have extended solid solubility into ternary systems: CaZn11, CaZn13 and Mg2Ca form substitutional solid solutions where Mg substitutes for Zn atoms in the first two compounds, and Zn substitutes for both Ca and Mg atoms in Mg2Ca. The isothermal section of the Ca–Mg–Zn phase diagram at 335 °C was constructed on the basis of the obtained experimental results. The morphologies of the diffusion couples in the Ca–Mg–Zn phase diagram at 335 °C were studied. Depending on the terminal compositions of the diffusion couples, the two-phase regions in the diffusion zone have either a tooth-like morphology or contain a matrix phase with isolated and/or dendritic precipitates.

An evaluation of the potential yield of indium recycled from end-of-life LCDs: A case study in China

With the advances in electronics and information technology, China has gradually become the largest consumer of household appliances (HAs). Increasingly, end-of-life (EOL) HAs are generated in China. EOL recycling is a promising strategy to reduce dependence on virgin production, and indium is one of the recycled substances. The potential yield of indium recycling has not been systematically evaluated in China thus far. This paper estimates the potential yield of recycled indium from waste liquid crystal displays (LCDs) in China during the period from 2015 to 2030. The quantities of indium that will be used to produce LCDs are also predicted. The estimates focus on the following three key LCD waste sources: LCD TVs, desktop computers and portable computers. The results show that the demand for indium will be increasing in the near future. It is expected that 350 tonnes of indium will be needed to produce LCDs in China in 2035. The indium recycled from EOL LCDs, however, is much less than the demand and only accounts for approximately 48% of the indium demand. The sustainable index of indium is always less than 0.5. Therefore, future indium recycling efforts should focus on the development of recycling technology and the improvement of the relevant policy.

Engineering a highly elastic human protein–based sealant for surgical applications

A highly elastic and adhesive photocrosslinkable surgical sealant using a modified human protein controls liquid leakages without the need for suturing. A stretchy, sticky alternative to sutures Repairing tissue ruptures during surgery can be complicated: Suturing requires piercing an already damaged tissue, and sealants such as glues may not match the material properties of the tissue, leading to subsequent leakage or rupture. Annabi et al. capitalized on the elastic properties of the human protein tropoelastin to engineer a photocrosslinkable hydrogel sealant material. The injectable material, MeTro, successfully sealed surgical incisions in blood vessels in rats and in lungs in pigs without evidence of leakage or rupture. Tunable elastic hydrogel sealants offer a promising adhesive, biocompatible, biodegradable material for tissue repair. Surgical sealants have been used for sealing or reconnecting ruptured tissues but often have low adhesion, inappropriate mechanical strength, cytotoxicity concerns, and poor performance in biological environments. To address these challenges, we engineered a biocompatible and highly elastic hydrogel sealant with tunable adhesion properties by photocrosslinking the recombinant human protein tropoelastin. The subcutaneous implantation of the methacryloyl-substituted tropoelastin (MeTro) sealant in rodents demonstrated low toxicity and controlled degradation. All animals survived surgical procedures with adequate blood circulation by using MeTro in an incisional model of artery sealing in rats, and animals showed normal breathing and lung function in a model of surgically induced rat lung leakage. In vivo experiments in a porcine model demonstrated complete sealing of severely leaking lung tissue in the absence of sutures or staples, with no clinical or sonographic signs of pneumothorax during 14 days of follow-up. The engineered MeTro sealant has high potential for clinical applications because of superior adhesion and mechanical properties compared to commercially available sealants, as well as opportunity for further optimization of the degradation rate to fit desired surgical applications on different tissues.

Effect of removing Kupffer cells on nanoparticle tumor delivery

Significance Nanomaterials are developed for treating and diagnosing cancer, but only 0.7% (median) are delivered to a solid tumor. To address this delivery problem, we are examining each biological barrier to determine its impact on tumor delivery. Because the liver sequesters up to 70% of nanomaterials, in this study, we asked, if liver Kupffer cells were removed, what is the impact on tumor delivery? While we demonstrate that the tumor delivery increased up to 150 times, we achieved 2% for nanomaterials of different size, material, and tumor type. This suggests the need to focus on tumor pathophysiology to increase delivery efficiency, since this approach led to a greater availability of nanoparticles in the blood, but 98% did not accumulate in solid tumors. A recent metaanalysis shows that 0.7% of nanoparticles are delivered to solid tumors. This low delivery efficiency has major implications in the translation of cancer nanomedicines, as most of the nanomedicines are sequestered by nontumor cells. To improve the delivery efficiency, there is a need to investigate the quantitative contribution of each organ in blocking the transport of nanoparticles to solid tumors. Here, we hypothesize that the removal of the liver macrophages, cells that have been reported to take up the largest amount of circulating nanoparticles, would lead to a significant increase in the nanoparticle delivery efficiency to solid tumors. We were surprised to discover that the maximum achievable delivery efficiency was only 2%. In our analysis, there was a clear correlation between particle design, chemical composition, macrophage depletion, tumor pathophysiology, and tumor delivery efficiency. In many cases, we observed an 18–150 times greater delivery efficiency, but we were not able to achieve a delivery efficiency higher than 2%. The results suggest the need to look deeper at other organs such as the spleen, lymph nodes, and tumor in mediating the delivery process. Systematically mapping the contribution of each organ quantitatively will allow us to pinpoint the cause of the low tumor delivery efficiency. This, in effect, enables the generation of a rational strategy to improve the delivery efficiency of nanoparticles to solid tumors either through the engineering of multifunctional nanosystems or through manipulation of biological barriers.

Recycling of indium from waste LCD: A promising non-crushing leaching with the aid of ultrasonic wave

The tremendous amount of end-of-life liquid crystal displays (LCDs) has become one of the prominent sources of waste electrical and electronic equipment (WEEE) in recent years. Despite the necessity of safe treatment, recycling indium is also a focus of waste LCD treatment because of the scarcity of indium. Based on the analyses of the structure of Indium Tin Oxide (ITO) glass, crushing is demonstrated to be not required. In the present research, a complete non-crushing leaching method was firstly adopted to recycle indium from waste LCDs, and the ultrasonic waves was applied in the leaching process. The results demonstrated that indium can be leached efficiently with even a low concentration of chloride acid (HCl) without extra heating. About 96.80% can be recovered in 60mins, when the ITO glass was leached by 0.8MHCl with an enhancement of 300W ultrasonic waves. The indium leaching process is abridged free from crushing, and proves to be of higher efficiency. In addition, the ultrasonic wave influence on leaching process was also explained combing with micron-scale structure of ITO glass.

Morphological and Crystallographic Characterizations of the Ca-Mg-Zn Intermetallics Appearing in Ternary Diffusion Couples

In the present research, seven multi-phase diffusion couples, with terminal alloys having different microstructural features, were prepared and annealed for 4 weeks at 335°C. The phase relations and change of morphological characteristics of each phase were studied along the diffusion zone by means of scanning electron microscopy/energy dispersive X-ray spectroscopy and quantitative electron probe microanalysis. Depending on the different terminal compositions of the diffusion couples, the morphological evolution in the diffusion zone can be: tooth-like, matrix phase with isolated and/or dendritic precipitates. Electron back-scattered diffraction analysis was carried out to investigate the crystal orientation of the ternary compounds and the crystal orientation relations at the interface of the diffusion zones.

Fiber Laser Deposition of Nickel-Based Superalloys Using Filler Wire Feed

In this work, a continuous wave fiber laser welding system was used to deposit nickel-based superalloys Inconel 718 (IN 718) and Waspaloy using filler wire feed sources. The multi-bead and multi-layer deposits that were manufactured were characterized in terms of the macro- and microstructures, defects, and hardness in both the as-deposited and fully heat treated conditions. The tensile properties of the deposits in the heat treated condition were also determined and compared to the existing aerospace materials specifications. Using optimized laser processing parameters, high strength deposits could be manufactured, though minor weld metal liquation cracking for IN718 and strain-age cracking for Waspaloy were present, which compromised slightly the ductility as compared to wrought aerospace specifications for the two alloys. The successful development of the direct laser deposition process using wire feeding indicates the potential of employing the fiber laser technology to manufacture nickel-based superalloy aerospace components.Copyright

Nanogels for biomedical applications: Drug delivery, imaging, tissue engineering, and biosensors

Nanogels have attracted much attention in the recent decades due to the combined properties of nanotechnology and cross-linking gel-like materials. These nanogels show great biocompatibility and biodegradability both in vitro and in vivo studies and have been widely used into biomedical science in terms of imaging, diagnostics, drug delivery, tissue engineering, biosensors, etc. The physicochemical properties (sizes, shapes, charges, and surface chemistries) can be easily tuned, which offer nanogels many advantages as nanocarrier for delivery of small molecules, proteins, genes, and other therapies. Incorporation of nanoparticles with a scaffold or hydrogel provides the ability to manipulate nanoscale parameters of scaffold for the development of 3D printing technology in the field of tissue engineering. In addition, these nanogels can sense and respond to environmental stimuli such as temperature, pH, light, mechanical stress, electric, magnetic field and glucose concentration. The special properties and simultaneously possesses characteristic of hydrogel and nanoparticle system make them potential candidates for sensory elements of biosensor.

The Ca-Rich Corner of the Al-Ca-Zn System

In this work, the partial isothermal section of the Al-Ca-Zn system in the region between 33.3 and 100 at.% Ca has been investigated at 350°C using key alloys. The actual composition of the alloys is measured by inductively coupled plasma technique. Phase relations and solubility limits of the binary and ternary compounds have been determined by means of electron probe microanalysis and X-ray diffraction. In the current work, a new ternary compound has been identified in this region with the Al9Ca31Zn10 (IM1) composition. Binary compound Al14Ca13 (IM2) has an extended solid solubility into the ternary system. The homogeneity ranges of the Al2Ca, the MgNi2-type C36 phase Al2-xCaZnx (0.28≤x≤0.70) (IM3) at 350°C and CaZn2 compounds in the pseudobinary Al2Ca-CaZn2 section have been determined at 350°C and the results are combined with the literature to construct the partial vertical Al2Ca-CaZn2 section and partial isothermal Al-Ca-Zn section at 350°C.

Microstructure and Creep Property of As-Cast Mg-6Al-XSr(x=0, 2, 3) Alloys

The microstructure and creep property of as-cast Mg-6Al-xSr(x=0, 2,3) alloys were studied. Results showed that the branch-like Al4Sr phase is the main precipitating phase in these alloys containing Sr. Their secondary creep rates under the applied stress of 70MPa at 175°Cdecreased with the increasing in the content of Sr and reached the minimum value of 1.4×10-8s-1 in the Mg-6Al-3Sr alloy, which is one thirtieth of secondary creep rates of the Mg-6Al alloy. It was mainly attributed to Al4Sr, which effectively hindered the grain boundaries sliding and dislocation motion in the creep.