Understanding of the electrochemical behaviors of aqueous zinc-manganese batteries:Reaction processes and failure mechanisms

As one of the most common cathode materials for aqueous zinc-ion batteries(AZIBs),manganese oxides have the advantages of abundant reserves,low cost,and low toxicity.However,the electrochemical mechanism at the cathode of aqueous zinc-manganese batteries(AZMBs) is complicated due to different electrode materials,electrolytes and working conditions.These complicated mechanisms severely limit the research progress of AZMBs system and the design of cells with better performance.Hence,the mechanism of AZMBs currently recognized by most researchers according to the classification of the main ions involved in the faradaic reaction is introduced in the review.Then a series of reasons that affect the electrochemical behavior of the battery are summarized.Finally,the failure mechanisms of AZMBs over prolonged cycling are discussed,and the current insufficient research areas of the system are explained,along with the direction of further research being prospected.

Changing Trend and Influencing Factors of Rice Production Cost in China

Rice is one of the three major food crops in China.The change of its production cost is related to food security and farmers'income in China.This paper analyzes the changing trend of rice production cost in China from 2009 to 2019,analyzes the factors leading to the change from the aspects of land scale,labor force structure,agricultural science and technology level,etc.On this basis,this paper puts forward measures and suggestions to reduce rice production cost and improve farmers'income.

Discovery and druggability evaluation of pyrrolamide-type GyrB/ParE inhibitor against drug-resistant bacterial infection

The bacterial ATP-competitive GyrB/ParE subunits of type II topoisomerase are important anti-bacterial targets to treat super drug-resistant bacterial infections.Herein we discovered novel pyrrolamide-type GyrB/ParE inhibitors based on the structural modifications of the candidate AzD5099 that was withdrawn from the clinical trials due to safety liabilities such as mitochondrial toxicity.The hydroxyisopropyl pyridazine compound 28 had a significant inhibitory effect on Gyrase(GyrB,IC_(50)=49 nmol/L)and a modest inhibitory effect on TopoⅣ(ParE,IC_(50)=1.513μmol/L)of Staphylococcus aureus.It also had significant antibacterial activities on susceptible and resistant Gram-positive bacteria with a minimum inhibitory concentration(MIC)of less than 0.03μg/mL,which showed a time-dependent bactericidal effect and low frequencies of spontaneous resistance against S.aureus.Compound 28 had better protective effects than the positive control drugs such as DS-2969(5)and AZD5099(6)in mouse models of sepsis induced by methicillin-resistant Staphylococcus aureus(MRSA)infection.It also showed better bactericidal activities than clinically used vancomycin in the mouse thigh MRSA infection models.Moreover,compound 28 has much lower mitochondrial toxicity than AZD5099(6)as well as excellent therapeutic indexes and pharmacokinetic properties.At present,compound 28 has been evaluated as a pre-clinical drug candidate for the treatment of drug-resistant Gram-positive bacterial infection.On the other hand,compound 28 also has good inhibitory activities against stubborn Gram-negative bacteria such as Escherichia coli(MIC=1μg/mL),which is comparable with the most potent pyrrolamide-type GyrB/ParE inhibitors reported recently.In addition,the structure-activity relationships of the compounds were also studied.

The formation kinetics and control of biofilms by three dominant fungi species isolated from groundwater

Filamentous fungi can enter drinking water supply systems in various ways,and exist in suspended or sessile states which threatens the health of individuals by posing a high risk of invasive infections.In this study,the biofilms formation kinetics of the three genera of fungal spores,Aspergillus niger(A.niger),Penicillium polonicum(P.polonicum)and Trichoderma harzianum(T.harzianum)isolated fromthe groundwater were reported,as well as the effects of water quality parameters were evaluated.In addition,the efficiency of low-concentrations of chlorine-based disinfectants(chlorine,chlorine dioxide and chloramine)on controlling the formation of fungal biofilms was assessed.The results showed that the biofilms formation of the three genera of fungi could be divided into the following four phases:induction,exponential,stationary and sloughing off.The optimum conditions for fungal biofilms formation were found to be neutral or weakly acidic at 28°C with rich nutrition.In fact,A.niger,P.polonicum,and T.harzianum were not observed to form mature biofilms in actual groundwater within 120 hr.Carbon was found to have the maximum effect on the fungal biofilms formation in actual groundwater,followed by nitrogen and phosphorus.The resistance of fungal species to disinfectants during the formation of biofilms decreased in the order:A.niger>T.harzianum>P.polonicum.Chlorine dioxide was observed to control the biofilms formation with maximum efficiency,followed by chlorine and chloramine.Consequently,the results of this study will provide a beneficial understanding for the formation and control of fungal biofilms.

Review about PD and breakdown induced by conductive particles in an insulating liquid

In insulating liquid,a conductive particle becomes charged through the interaction with a conductor exposed to an applied field.Then,it migrates in the action of both electric field and fluid and causes the enhancement of local field when it is in proximity of the conductor with opposite polarity.The enhancement will lead to partial discharge(PD)and may even ignite full gap breakdown in special cases.This study reviews comprehensive researches relevant to these topics.In the first place,several theoretical methods about how to obtain the charges held by a conductive particle with known potential are introduced,so are experimental methods.Then,forces acting on the charged particle in liquid are classified,and its migration characteristics,as well as influential factors,are described.Subsequently,PD and breakdown mechanisms of liquid initiated by conductive particles are presented.The latter involves two cases:electric-field enhancement when the particle concentration is low and bridging phenomenon when it is high.At last,two important,but frequently ignored factors,i.e.dielectric barrier and oil flow,are highlighted,and the authors’suggestions for future work are put forward.