Age Structure and Change Trend of Tobacco Farmers:A Case Study of Shashi Town,Liuyang City,Hunan Province

Taking the tobacco-growing area of Shashi Town,Liuyang City as the object,the number of registered,newly added and resigned tobacco farmers in each year,average age,number and proportion of tobacco farmers of different ages,number and proportion of tobacco farmers born in different eras,as well as planting scale and planting history of flue-cured tobacco in the last 10 years were analyzed statistically.The results showed that the number of tobacco farmers in Shashi Town showed a rapid decline trend from 2012 to 2018,while the average age continuously increased,and the average planting scale rose in a wave like way.From 2019 to 2021,the decline rate of the number of tobacco farmers slowed down,and the average planting scale continuously increased,while the aging of tobacco farmers accelerated.Meantime,the birth years of tobacco farmers were further concentrated in the 1960s,and they were mainly at the age of 50-59.The tobacco industry in Shashi Town of Liuyang City is facing the crisis of aging tobacco farmers and no successor of flue-cured tobacco planting,and it is predicted that the next 5-10 years will continue the change trend from 2019 to 2021.

Preparation of antifouling ultrafiltration membranes from copolymers of polysulfone and zwitterionic poly(arylene ether sulfone)s

The past few decades have witnessed rapid gains in our demands of antifouling membranes such as water purification membranes and hemodialysis membranes.A variety of methodologies have been proposed for improving the antifouling performance and the hemocompatibility of the membranes.In this study,a series of copolymers(PSF-PESSB)containing polysulfone(PSF)and poly(arylene ether sulfone)bearing pendant zwitterionic sulfobetaine groups(PESSB)were prepared via one-pot polycondensation.Subsequently,the ultrafiltration(UF)membranes were prepared from different zwitterion-containing copolymers.The prepared membranes showed high thermal stability and mechanical properties.Besides,it also displayed attractive antifouling performance and blood compatibility.Compared with the original PSF membrane,the amount of protein absorption on the modified membrane was reduced;the flux recovery ratio and the resistance to blood cells were significantly improved.The results of this work suggest that PSF-PESSB membranes are expected to be applied in blood purification.The introduction of zwitterion-containing polymers to membranes paves ways for developing advanced hemodialysis technologies for crucial process.

Highly stable side-chain-type cardo poly(aryl ether ketone)s membranes for vanadium flow battery

Vanadium flow batteries(VFBs)have drawn considerable attention as an emerging technology for largescale energy storage systems(ESSs).One of the pivotal challenges is the availability of eligible ion exchange membranes(ICMs)that provide high ion selectivity,proton conductivity,and stability under rigorous condition.Herein,a‘side-chain-type’strategy has been employed to fabricate highly stable phenolphthalein-based cardo poly(arylene ether ketone)s(PAEKs)membrane with low area resistance(0.058Ωcm^(2)),in which flexible alkyl spacers effectively alleviated inductive withdrawing effect from terminal ion exchange groups thus enabling a stable backbone.The assembled VFBs based on PAEKs bearing pendent alkyl chain terminated with quaternary ammonium(Q-PPhEK)demonstrated an energy efficiency above 80%over 700 cycles at 160 mA/cm^(2).Such a remarkable results revealed that the side-chain-type strategy contributed to enhancing the ICMs stability in strong oxidizing environment,meanwhile,more interesting backbones would be woken with this design engaging in stable ICMs for VFBs.

Longitudinal association of egg consumption habits with blood lipids among Chinese adults: results from the Prediction for Atherosclerotic Cardiovascular Disease Risk in China project

To the Editor:According to guidelines from western countries as well as China,dietary patterns with low intake of cholesterol have been widely recommended for maintaining ideal lipid levels.As one of the major sources of both high-quality protein and dietary cholesterol,eggs have always been the focus in terms of diet.Although increased lipid levels induced by high egg intake have been revealed by randomized controlled trials(RCTs),they may not be sufficient to reflect the impacts of habitual egg intake due to high doses of egg intake of more than 7 eggs/week or even 14 eggs/week.Further,RCTs typically have shorter intervention periods of about 3 months,which may not observe a stable association due to homeostasis in cholesterol metabolism of human beings.[1,2]Up to now,only three cohorts assessed the associations of egg intake with lipid levels or dyslipidemia,and the findings were still controversial.One recent cohort study has reported the non-significant association between higher egg intake(≥7 vs.1 eggs/week)and lipid profiles.On the other hand,another cohort from Spain found that compared with<1 egg/week,>4 eggs/week had no significant influence on total cholesterol(TC)and triglyceride(TG),but significantly decreased high-density lipoprotein cholesterol(HDL-C)levels.[4]However,none of these cohorts were from developing countries,and the association between moderate egg intake and lipid profiles has not been well illustrated.Egg consumption in China,a representative of developing countries,is relatively higher,and it may be possible to better explore the appropriate range of egg intake.