Comprehensively Improved Electrochemical Performance of Lithium-Sulfur Batteries by “Chemical Anchors” and Lithium Anode Modification

Lithium-sulfur battery is considered to be one of the most promising contenders for the next generation high-energy storages due to their high theoretical energy density (~2600 W h kg-1). However, a series of issues, especially for the dissolution of lithium polysulfides (LiPSs) with their “shuttle effect” and dendrite formation on the lithium anode, greatly limit their widely commercial applications. Starting from a brief overview of conventional methods to solve these problems, the achievements spotlighted in this research work mainly focus on the structure design of cathode materials by employing “chemical anchors” to effectively suppress the diffusion of LiPSs, as well as the Li anode modification to suppress the dendrite formation, thus the electrochemical performance of Li-S batteries can be comprehensively improved. The synthetic methods, characterization techniques with electrochemical performance are presented. Further work plans and implications are proposed regarding optimize the structure of materials, preparation technology, and to better understand the role of these “chemical anchors” and the protection mechanism of Li anode. Proposing with some perspectives and future research efforts, this research is hoped to provide an in-depth understanding and offer avenues in the rational design of Li-S batteries with long cycle life and high energy/power density in the near future

An Analysis of Power Relations in the Redevelopment of Urban Villages - Three Case Studies in Guangzhou, China

This thesis studies the power relations among the government, the village collective economic organization (VCEO), and the villagers in the redevelopment of urban villages in China by analyzing three cases - Liede Village, Yangji Village, and Wenchong Village in Guangzhou municipality. The case studies show that government involvement is the major force that drives the redevelopment and the degree of government involvement is based on the government's agenda rather than the needs of villages. Although the urban village only has limited negotiation power, villagers' active participation and continuous engagement can assist the redevelopment of urban villages and help to achieve a desirable redevelopment plan and compensation scheme. It also indicates that strong support from government and a collaborative partnership among the local government, the village collective economic organization (VCEO), and urban villagers are the keys to successful urban village redevelopments

Programmed Design of a Lithium–Sulfur Battery Cathode by Integrating Functional Units

Sulfur is considered to be one of the most promising cathode materials due to its high theoretical specific capacity and low cost. However, the insulating nature of sulfur and notorious “shuttle effect” of lithium polysulfides (LiPSs) lead to severe loss of active sulfur, poor redox kinetics, and rapid capacity fade. Herein, a hierarchical electrode design is proposed to address these issues synchronously, which integrates multiple building blocks with specialized functions into an ensemble to construct a self‐supported versatile cathode for lithium–sulfur batteries. Nickel foam acts as a robust conductive scaffold. The heteroatom‐doped host carbon with desired lithiophilicity and electronic conductivity serving as a reservoir for loading sulfur can trap LiPSs and promote electron transfer to interfacial adsorbed LiPSs and Ni3S2 sites. The sulfurized carbon nanofiber forest can facilitate the Li‐ion and electron transport and retard the LiPSs diffusion as a barrier layer. Sulfiphilic Ni3S2 acts as both a chemical anchor with strong adsorption affinity to LiPSs and an efficient electrocatalyst for accelerating kinetics for redox conversion reactions. Synergistically, all functional units promote the lithium ion coupled electron transfer for binding and redox conversion of LiPSs, resulting in high reversible capacities, remarkable cycle stability, and excellent rate capability

On the special oxidation mechanism of a Mg-Y-Al alloy contained LPSO phase at high temperatures

This work investigated the oxidation of Mg-11Y-1Al alloy in Ar-20%O2 at 500{\deg}through multiscale characterization. The results show that the network-like long-period stacking ordered(LPSO) phase decomposed into a needle-like LPSO phase and a polygonal Mg24Y5 phase. The needle-like LPSO phase resulted in the formation of a high-dense of needle-like oxide at the oxidation front of the area initially occupied by the network-like LPSO phase. The further inward oxygen would diffuse along the needle-like oxide-matrix interfaces and react with Y in the surrounding Mg matrix, resulting in the lateral growth of these needle-like oxides. Finally, the discrete needle-like oxides were interconnected to form a thicker and continuous oxide scale which could be more effective in hindering the elemental diffusion. Meanwhile, Al could partially enter the Y2O3 oxide scale and formed a strengthened (Y,Al)O oxide scale which could show a greater resistance to cracking and debonding

Design Multilayer Antireflection Coatings for Terrestrial Solar Cells

In order to analyze the influence of methods to design antireflection coatings (ARCs) on reflectivity of broadband solar cells, we provide detailed analyses about the ARC coupled with a window layer and the refractive index dispersion effect of each layer. By multidimensional matrix data simulation, two methods were employed to measure the composite reflection of a Si/ZnS double-layer ARC within the spectral ranges of 300–870 nm (dual junction) and 300–1850 nm (triple junction) under AM1.5 solar radiation. A comparison study, between the results obtained from the commonly used weighted average reflectance method (WAR) and that from the introduced effective average reflectance method (EAR), shows that the optimization of ARC by EAR method is convenient and feasible

A Versatile Approach for Siteâ Specific Lysine Acylation in Proteins

Using amber suppression in coordination with a mutant pyrrolysylâ tRNA synthetaseâ tRNAPyl pair, azidonorleucine is genetically encoded in E. coli. Its genetic incorporation followed by traceless Staudinger ligation with a phosphinothioester allows the convenient synthesis of a protein with a siteâ specifically installed lysine acylation. By simply changing the phosphinothioester identity, any lysine acylation type could be introduced. Using this approach, we demonstrated that both lysine acetylation and lysine succinylation can be installed selectively in ubiquitin and synthesized histone H3 with succinylation at its K4 position (H3K4su). Using an H3K4suâ H4 tetramer as a substrate, we further confirmed that Sirt5 is an active histone desuccinylase. Lysine succinylation is a recently identified postâ translational modification. The reported technique makes it possible to explicate regulatory functions of this modification in proteins.Azidonorleucine, an azideâ containing amino acid, is genetically encoded and incorporated into model proteins. This incorporation followed by traceless Staudinger ligation potentiates the synthesis of proteins with a myriad of siteâ specific lysine acylations.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/137311/1/anie201611415-sup-0001-misc_information.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/137311/2/anie201611415_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/137311/3/anie201611415.pd

CO2 Corrosion of Low Carbon Steel Under the Joint Effects of Time-Temperature-Salt Concentration

The time-dependent effects of temperature and salt (NaCl) concentration on the corrosion behavior of carbon steel in CO2-saturated environments were explored using various electrochemical techniques coupled with XRD, Raman spectroscopy, and SEM/FIB examinations. At constant salt level, corrosion rate increases, and stabilizes when the temperature is below 60°C. When temperature is higher than 60°C, corrosion rate firstly increases, reaches an apex, and then starts decreasing continuously. The magnitude of the decrease is inversely proportionally to the salt concentration, which is attributed to the microstructure of dual-layer FeCO3 scale. Polarization experiments indicate the anodic process is more affected by salt concentration than temperature while the opposite is true for the cathodic kinetics. Although chloride is not detected in the corrosion scale, it is regarded to have significant influence on the nucleation and growth of FeCO3 and therefore the properties (e.g., thickness and compactness) of the corrosion scales. Lastly, a mechanism is proposed for the evolution of corrosion scales on carbon steel in CO2 saturated environment as a function of temperature and salt concentration

Correlation analysis between foot deformity and diabetic foot with radiographic measurement

BackgroundFoot deformity is a risk factor for diabetic foot ulcer. This study was aimed to investigate the relationship between hallux valgus (HV) and diabetic foot through the radiographic measurement.MethodsThe patients with diabetic foot hospitalizing in the Department of Endocrinology, the First Affiliated Hospital of Chongqing Medical University from September 2016 to June 2020 were selected. Then the foot plain X-ray radiographs were completed, and the size of HV angle (HVA) was measured. Their clinical data were collected, and the ulcer recurrence rate, amputation rate and mortality rate of the patients were followed up.ResultsA total of 370 patients were included. According to HVA, patients were divided into non-HV group (HVA<15°), and mild (15°≤HVA ≤ 20°), moderate (20°<HVA ≤ 40°) and severe (HVA>40°) HV groups. The age, height, BMI, smoking history and glycosylated hemoglobin level among the non-HVA, mild, moderate, and severe HV group (P<0.05), while smoking history, HbA1c, eGFR and autonomic neuropathy were significantly lower in HV group than those in non-HV group (P<0.05). The ulcer area in patients with moderate HV was larger than that in non-HV patients, and the severity of infection in patients with severe HV was significantly higher than that the other three groups (P<0.05).ConclusionThe occurrence of HV is not only related to age and BMI, but also to the creatinine and eGFR level, autonomic neuropathy, lower limb arteriosclerosis occlusion, coronary heart disease and hypertension. Therefore, more attention should be paid to renal function screening, neuropathy screening and evaluation of lower extremity vascular lesions in patients with diabetes, especially those with moderate or higher HV