Tuning the crystalline and electronic structure of ZrO_(2)via oxygen vacancies and nano-structuring for polysulfides conversion in lithium-sulfur batteries

The recent emergence of tetragonal phases zirconium dioxide(ZrO_(2))with vacancies has generated significant interest as a highly efficient and stable electrocatalyst with potential applications in trapping polysulfides and facilitating rapid conversion in lithium-sulfur batteries(LSBs).However,the reduction of ZrO_(2)is challenging,even under strong reducing atmospheres at high temperatures and pressures.Consequently,the limited presence of oxygen vacancies results in insufficient active sites and reaction interfaces,thereby hindering practical implementation.Herein,we successfully introduced abundant oxygen vacancies into ZrO_(2)at the nanoscale with the help of carbon nanotubes(CNTs-OH)through hydrogen-etching at lower temperatures and pressures.The introduced oxygen vacancies on ZrO_(2-x)/CNTs-OH can effectively rearrange charge distribution,enhance sulfiphilicity and increase active sites,contributing to high ionic and electronic transfer kinetics,strong binding energy and low redox barriers between polysulfides and ZrO_(2-x).These findings have been experimentally validated and supported by theory calculations.As a result,LSBs assembled with the ZrO_(2-x)/CNTs-OH modified separators demonstrate excellent rate performance,superior cycling stability,and ultra-high sulfur utilization.Especially,at high sulfur loading of 6 mg cm^(-2),the area capacity is still up to 6.3 mA h cm^(-2).This work provides valuable insights into the structural and functional optimization of electrocatalysts for batteries.

Dual metal atom catalysts:Advantages in electrocatalytic reactions

The dual-metal-atom catalysts(DACs)have aroused much attention as they possess the advantages of single-atom and metal alloy catalysts.And the DACs have exhibited enhanced performance in various electrocatalytic reactions,such as hydrogen/oxygen evolution and oxygen/carbon dioxide/nitrogen reduction.In this review,we mainly overview the latest understanding of the advantages of DACs for these reactions.This review will start with the familiar characterization methods for DACs,then the primary synthesis strategies for DACs will be discussed.Emphasis is given to the advantages of DACs in catalytic reactions,including the adsorption and activation,electronic structure regulation,breaking scaling relations,reducing energy barriers,cascading and coupling,synergy effect,and providing mechanism research platforms.Finally,personal perspectives and challenges for the further development of DACs are briefly discussed.

Tuning Li nucleation and growth via oxygen vacancy-enriched 3D flexible self-supporting protection layer of P-Mn_(3)O_(4-x)for advanced lithium-sulfur batteries

Lithium sulfur batteries have attracted much attention due to their high theoretical specific energy and environmental friendliness.However,the practical application is severely plagued by the cycling life issues resulting from the uncontrollable generation and growth of Li dendrites.Herein,an innovative 3D flexible self-supporting Li anode protection layer of P-Mn_(3)O_(4-x)is constructed via a facile solvothermal method followed by an annealing process.Benefiting from the rich oxygen vacancies coupled with the 3D flexible self-supporting skeleton,abundant lithiophilic sites and high ionic conductivity are obtained,which succeed in guiding Li+homogeneous adsorption and redistribution,accelerating Li+diffusion rate,inducing Li+uniform deposition and nucleation.DFT calculations and experimental results conclusively demonstrate such a protection mechanism.Meanwhile,the effective anchoring and catalytic nature of polar P-Mn_(3)O_(4-x)can also be applied as an immobilization-diffusion-conversion host to improve polysulfides redox.Taking advantage of these merits,super-stable functions for Li symmetric cell matched with P-Mn_(3)O_(4-x)layer are achieved,which exhibits an ultralong lifespan of>5000 h with an ultralow overpotential of 20 m V,far lower than that of bare Li symmetric cell(overpotential of 800 m V only after 250 h)at high current densities of 5 m A cm^(-2)and high plating/stripping capacity of 10 m A h cm^(-2).Even in Li|P-Mn_(3)O_(4-x)||S full cell at 1 C,a high initial discharge specific capacity of 843.1 m A h g^(-1)is still delivered with ultralow capacity fading rate of 0.07%per cycle after 250 cycles,further confirming the synergistic regulation of P-Mn_(3)O_(4-x)for Li nucleation behavior.This work illustrates a sufficient guarantee of 3D protection layer coupled with oxygen vacancies in guiding Li diffusion and nucleation behavior and provides new guidance for promoting the development of advanced Li-S batteries.

Research on the Problem Investigation and Standardized Improvement Paths of Farmers’ Cooperatives

Farmers’cooperatives are an important force to promote agricultural and rural modernization and rural revitalization.From an investigation,it is found that the development of some farmers’cooperatives is not standardized.Prominent problems are as follows:firstly,the operating mechanism is not standardized,and there is a contradiction between democratic decision-making and management efficiency;secondly,the supervision and management are not standardized,and some cooperatives even resort to deceit to obtain financial subsidies;thirdly,the distribution mechanism is not standardized,and core members invade the interests of small peasant households,so the motivation of ordinary peasant households to participate in cooperatives is not high.It is recommended to strengthen the assessment and supervision of cooperatives,implement the"late funding"model,improve the efficiency of financial support,strengthen the training of farmers,establish a interest linkage mechanism of farmers and cooperatives,protect the rights of members,and promote the standardized development of farmers’cooperatives.

Unsupervised Feature Selection Using Structured Self-Representation

Unsupervised feature selection has become an important and challenging problem faced with vast amounts of unlabeled and high-dimension data in machine learning. We propose a novel unsupervised feature selection method using Structured Self-Representation( SSR) by simultaneously taking into account the selfrepresentation property and local geometrical structure of features. Concretely,according to the inherent selfrepresentation property of features,the most representative features can be selected. Mean while,to obtain more accurate results,we explore local geometrical structure to constrain the representation coefficients to be close to each other if the features are close to each other. Furthermore,an efficient algorithm is presented for optimizing the objective function. Finally,experiments on the synthetic dataset and six benchmark real-world datasets,including biomedical data,letter recognition digit data and face image data,demonstrate the encouraging performance of the proposed algorithm compared with state-of-the-art algorithms.

Primary urachal adenocarcinoma: a rare case report

Primary urachal carcinoma is a very rare cancer with a poor prognosis.It generally presents as a highgrade,high-stage tumor,and in most cases the patient has developed regional or distant metastasis at the time of presentation.Here,we report a very interesting case of primary urachal adenocarcinoma with signet ring cell carcinoma in a 58-year-old male who presented with a lower abdominal mass and discomfort.In this case,urachal carcinoma was successfully treated with surgery using an extended partial bladder cystectomy approach with excision of the urachal mass and umbilicus.The patient also underwent systematic chemotherapy with 5-fluorourical and cisplatin.During the 12-month follow-up period,the patient did not experience recurrence or metastasis.Overall,we found that an organ preserving extended partial cystectomy along with chemotherapy was an optimal treatment method that helped improve the patient's quality of the life with no recurrence of cancer so far.

Highly efficient and selective CO2 electro-reduction with atomic Fe-C-N hybrid coordination on porous carbon nematosphere

Carbon dioxide reduction(CO2RR)has become a promising way to address the energy and environmental crisis,of which the fundamental development of the optimal electrocatalysts is the crucial part.Herein,we develop Fe and N doping porous carb on n ematosphere(FeNPCN)as an excellent CO2RR electrocatalyst in aqueous electrolyte.Featuring with the high conductivity,pore structure and abundant Fe and N doping,FeNPCN exhibits high catalytic activity with a high faradaic selectivity of CO(94%)and long-term durability.Moreover,the ratio of CO and H2 can be changed by the applied potential for the different syngas related industry.Density functional theory(DFT)calculation results also reveal that the excellent catalytic activity is likely attributed to C and N hybrid coordination with atomic Fe.

On the modification of hypereutectic Al-Si alloys using rare earth Er

Hypereutectic Al-17.5Si （wt pct） and Al-25Si （wt pct） alloys with various content of rare earth Er were prepared by conventional casting technique. The effect of Er on the microstructure and properties of the hypereutectic Al-Si alloys was investigated using optical microscopy, scanning electron microscopy as well as friction and wear tests. It was found that optimal amount of Er exists in modifying the hypereutectic Al-Si alloys. An appropriate addition of Er improved the anti-wear properties, and reduced the friction coefficient of the hypereutectic Al-Si alloys studied. The primary silicon crystals in the hypereutectic Al-Si alloys were refined with the suitable addition of Er element. The modification mechanism was also discussed in this paper.

Performance of a zero-inertia model for irrigation with rapidly varied inflow discharges

The zero-inertia model is widely used for simulating surface flow in irrigation systems.This model is accurate when inflow discharge is constant.However,simulation of irrigation systems with rapidly varied inflow discharge is needed due to the development of real time control irrigation technology.Hence,the objective of this study is to validate the zero-inertia model with rapidly varied inflow discharge.For this purpose,twenty-three border irrigation tests at a range of inflow changes on different field slopes and roughness coefficients were conducted.Then,the sensitivity analyses of bed slope,infiltration parameters,and roughness coefficient were examined.The results indicate that the zero-inertia model predictions are in good agreement with field data in both advance/recession times and flow depths.The infiltration parameters were the most sensitive input variable of the zero-inertia model.The input variables have a more considerable impact on the recession phase than the advance phase.

Simulating advance distance in border irrigation systems based on the improved method of characteristics

Improving the simulation accuracy of the advance distance based on the method of characteristics is essential to develop numerical solutions for simulating surface irrigation.Instead of volume balance in the traditional method of characteristics(T-MC),the position of critical flow is determined to simulate the advance distance in the improved method of characteristics(I-MC),which is used in border irrigation systems with rapid variation in inflow discharge in the current research.Specifically,the zones of both subcritical and supercritical flow were firstly distinguished to determine the position of the critical flow point,which was also the upstream boundary of the wetting front region,and then the advance distance was calculated by applying the diffusive wave equation in the wetting front region.The results showed that the I-MC accurately simulated the advance distance with high determination coefficients(0.984-0.998)and low errors(root mean square error of 0.35-1.56 min and coefficient of residual mass of 0.01-0.06),which performed much better than the T-MC.The I-MC provided a suitable and simple numerical simulation tool to improve the establishment of numerical surface irrigation models.