Compact ultra-narrowband superconducting filter using N-spiral resonator with open-loop secondary coupling structure

A novel N-spiral resonator with open-loop secondary coupling structure(OLSCS) is proposed to realize a compact ultra-narrowband high temperature superconducting(HTS) filter. The coupling strength and polarity between the resonators can be significantly reduced and changed by introducing OLSCS, thus the required weak coupling can be achieved in a very compact size. A six-pole superconducting filter at 1701 MHz with a fractional bandwidth of 0.19% is designed to validate this method. The filter is fabricated on Mg O substrate with a compact size of 15 mm × 10 mm. The measured insertion loss is 0.79 d B, and the return loss is better than 17.4 d B. The experimental results show a good agreement with the simulations.

Nitrogen and fluorine co-doped graphene for ultra-stable lithium metal anodes

The heteroatom doping strategies have been utilized to effectively improve the performance of the carbon-based hosts,such as graphene,for lithium(Li)metal in high energy density lithium metal batteries.However,solely doped graphene hosts often need the assistance of other materials with either better lithiophilicity or electronic conductance to achieve smooth and efficient deposition of Li,which adds extra weight or volume.Herein,graphene co-doped by nitrogen and fluorine(NFG)is employed as a stable host for Li,where the N-doping provides lithiophilicity and electronic conductivity lacked by F-doping and the F-doping facilitates fast formation of solid electrolyte interphase(SEI)retarded by N-doping.The well regulation of Li plating/stripping and SEI formation is verified by quickly stabilized and small-magnitude voltage hysteresis,which stands out in Li hosts based on doped graphene and leads to excellent long-term cycling performance of NFG based electrodes.A voltage hysteresis of 20 mV is observed for more than 850 h in the symmetrical cell.The remarkable efficiency of lithium usage is confirmed by the highcapacity retention of a full cell paired with LiFePO_(4)(LFP),which exceeds 70%after 500 cycles.This work presents an innovative perspective on the control of Li plating/stripping by simultaneously introducing two kinds of dopants into graphene and paving the way for exploring practical Li metal batteries.

Textural Evolution of AZ31B Magnesium Alloy Sheets Undergoing Repeated Unidirectional Bending at Room Temperature

In this paper, repeated unidirectional bending （RUB）, was applied to improve the texture of AZ31B magnesium alloy sheets so as to enhance their stamping properties. The samples undergoing RUB were annealed at different temperatures. The mechanical properties, formability, textural components and microstructure of the samples before and after RUB were characterized and compared. It was found that the basal textural component was reduced dramatically by RUB, and that （1212） and （1211） textural components appeared. Annealing has a great effect on the mechanical properties of samples undergoing RUB. The plasticity and stamping formability of samples were greatly improved by RUB and annealing at 260℃ for 1 h, and elongation to fracture and Erichsen value were increased to 38% and 67%, respectively.

Biomass-derived activated carbon materials with plentiful heteroatoms for high-performance electrochemical capacitor electrodes

Activated carbons for electrochemical capacitor electrodes are prepared from soyabean using chemical activation with KOH. The pore size is easily controllable by changing the mass ratio between KOH and carbonized product. The as-prepared materials possess a large specific surface area, unique structure, well- developed hierarchical porosity and plentiful heteroatoms（mainly O and N）. Thus resulted in its high specific capacitance,good rate capacity and cycling stability. Moreover, attributing to worldwide availability, renewable nature and low-cost, activated carbon prepared from soyabean has a good potential in energy conversion and storage devices.

Research and test of the measurement sensing device for the downforce of no-till planter row unit gauge wheels

To effectively obtain the downforce of the gauge wheels in real time,mechanical models of the interaction among the ground,gauge wheels,gauge wheel arms,and depth adjustment lever were constructed.A measuring method was proposed for monitoring the downforce through a two-dimensional radial sensing device,and a corresponding prototype was designed.Through simulation analysis of the sensing device with ANSYS,a 45°angle was determined to exist between the strain gauge axis and the sensing device axis,and the Wheatstone bridging circuit of R1+R3−R5−R7(R stands for resistance strain gauge,different figures represent the strain gauge number)and R2+R4−R6−R8 was adopted.According to performance and calibration tests for the sensing device,the maximum interaction effect between the X and Y axes was 2.52%,and the output signal was stable and consistent.The standard error of the slope of the fitting equation of the downforce calculation model is 0.008.According to the field test,the average downforce of the gauge wheels was 1148,1017,843,and 713 N,at different sowing speeds of 6,8,10,and 12 km/h,respectively.The coefficients of variation were 0.40,0.41,0.62,and 0.71,respectively.The results indicate that the downforce fluctuation of the gauge wheels became more severe with increasing planting speed.Both the strain simulation analysis and field test verified that the measurement method is accurate and reliable,the performance of the sensing device is stable,the measurement method and sensing device meet the application requirements and lay a foundation for the research of accurate and stable control of downforce of no-till planter.

Effects of nanoscale quantum dots in male Chinese loaches (Misgurnus anguillicaudatus):Estrogenic interference action,toxicokinetics and oxidative stress

Quantum dots (QDs) have more and more attention as a novel example of nanocrystals due to their unique fluorescent characteristics. Recently, the toxicity and the potential environmental effects of QDs have become a research hotspot. In this work, in vivo endocrine disrupting effect, toxicokinetics and oxidative stress of QDs were characterized following the intraperitoneal dosing in Chinese loaches. Vitellogenin (Vtg) levels induced by E2 decreased significantly when administrated with the mixture of QDs and E2, which was consistent with the observations of histopathology in testes. The release of free Cd2+ from QDs and the non-specific adsorption of E2 by QDs might be the joint factors contributing to the inhibition of Vtg expression induced by E2 in the male Chinese loaches. In the muscle, bone, intestines, blood and testis, CdSe QDs reached the maximal concentration (C max) in approximately 1-h postinjection and subsequently presented downtrend with the prolonged time. Whereas, there were even increasing tendencies of CdSe QDs’ concentrations in the liver and kidney. It is educible that CdSe QDs can be persistent at least for 7 days, indicating the overall half-life of CdSe QDs in the fish body is very long. The measurement of hepatic superoxide dismutase (SOD) activity and reduced glutathione (GSH) content indicate that QDs have smaller effects on the antioxidative system of the organisms compared with free Cd2+ due to the effective prevention of the release of Cd by PEG coating of QDs. The comprehensive evaluation of QDs’ toxicity in the present study provides an essential and general framework towards more focused research on the elucidation of the biological effects of QDs in vivo.

Coupling evaluation for material removal and thermal control on precision milling machine tools

Machine tools are one of the most representative machining systems in manufacturing.The energy consumption of machine tools has been a research hotspot and frontier for green low-carbon manufacturing.However,previous research merely regarded the material removal(MR)energy as useful energy consumption and ignored the useful energy consumed by thermal control(TC)for maintaining internal thermal stability and machining accuracy.In pursuit of energy-efficient,high-precision machining,more attention should be paid to the energy consumption of TC and the coupling relationship between MR and TC.Hence,the cutting energy efficiency model considering the coupling relationship is established based on the law of conservation of energy.An index of energy consumption ratio of TC is proposed to characterize its effect on total energy usage.Furthermore,the heat characteristics are analyzed,which can be adopted to represent machining accuracy.Experimental study indicates that TC is the main energy-consuming process of the precision milling machine tool,which overwhelms the energy consumption of MR.The forced cooling mode of TC results in a 7%reduction in cutting energy efficiency.Regression analysis shows that heat dissipation positively contributes 54.1%to machining accuracy,whereas heat generation negatively contributes 45.9%.This paper reveals the coupling effect of MR and TC on energy efficiency and machining accuracy.It can provide a foundation for energyefficient,high-precision machining of machine tools.

Structure-based insights into recognition and regulation of SAM-sensing riboswitches

Riboswitches are highly conserved RNA elements that located in the 5’-UTR of m RNAs,which undergo real-time structure conformational change to achieve the regulation of downstream gene expression by sensing their cognate ligands.S-adenosylmethionine(SAM)is a ubiquitous methyl donor for transmethylation reactions in all living organisms.SAM riboswitch is one of the most abundant riboswitches that bind to SAM with high affinity and selectivity,serving as regulatory modules in multiple metabolic pathways.To date,seven SAM-specific riboswitch classes that belong to four families,one SAM/SAH riboswitch and one SAH riboswitch have been identified.Each SAM riboswitch family has a well-organized tertiary core scaffold to support their unique ligand-specific binding pocket.In this review,we summarize the current research progress on the distribution,structure,ligand recognition and gene regulation mechanism of these SAM-related riboswitch families,and further discuss their evolutionary prospects and potential applications.

Energy efficient cutting parameter optimization

Mechanical manufacturing industry consumes substantial energy with low energy efficiency. Increasing pressures from energy price and environmental directive force mechanical manufacturing industries to implement energy efficient technologies for reducing energy consumption and improving energy efficiency of their machining processes. In a practical machining process, cutting parameters are vital variables set by manufacturers in accordance with machining requirements of workpiece and machining condition. Proper selection of cutting parameters with energy consideration can effectively reduce energy consumption and improve energy efficiency of the machining process. Over the past 10 years, many researchers have been engaged in energy efficient cutting parameter optimization, and a large amount of literature have been published. This paper conducts a comprehensive literature review of current studies on energy efficient cutting parameter optimization to fully understand the recent advances in this research area. The energy consumption characteristics of machining process are analyzed by decomposing total energy consumption into electrical energy consumption of machine tool and embodied energy of cutting tool and cutting fluid. Current studies on energy efficient cutting parameter optimization by using experimental design method and energy models are reviewed in a comprehensive manner. Combined with the current status, future research directions of energy efficient cutting parameter optimization are presented.

An energy consumption prediction approach of die casting machines driven by product parameters

Die casting machines,which are the core equipment of the machinery manufacturing industry,consume great amounts of energy.The energy consumption prediction of die casting machines can support energy consumption quota,process parameter energy-saving optimization,energy-saving design,and energy efficiency evaluation;thus,it is of great significance for Industry 4.0 and green manufacturing.Nevertheless,due to the uncertainty and complexity of the energy consumption in die casting machines,there is still a lack of an approach for energy consumption prediction that can provide support for process parameter optimization and product design taking energy efficiency into consideration.To fill this gap,this paper proposes an energy consumption prediction approach for die casting machines driven by product parameters.Firstly,the system boundary of energy consumption prediction is defined,and subsequently,based on the energy consumption characteristics analysis,a theoretical energy consumption model is established.Consequently,a systematic energy consumption prediction approach for die casting machines,involving product,die,equipment,and process parameters,is proposed.Finally,the feasibility and reliability of the proposed energy consumption prediction approach are verified with the help of three die casting machines and six types of products.The results show that the prediction accuracy of production time and energy consumption reached 91.64%and 85.55%,respectively.Overall,the proposed approach can be used for the energy consumption prediction of different die casting machines with different products.