The immediate post-weaning period poses a major challenge on the survival of piglets. Similarly, newly hatched chicks face life threatening challenges due to enteric infections. In the past several years, in-feed anti...The immediate post-weaning period poses a major challenge on the survival of piglets. Similarly, newly hatched chicks face life threatening challenges due to enteric infections. In the past several years, in-feed antibiotics have been used to reduce these production problems and improve growth. However, in-feed antibiotics have been banned in many jurisdictions and therefore the most effective alternatives to infeed antibiotics must be developed. To date, several studies have been conducted to develop alternatives to antibiotics. One of the potential candidates as alternatives to in-feed antibiotics is resistant starch(RS). Resistance starch is a type of starch that resists enzymatic digestion in the upper parts of the gastrointestinal tract and therefore passes to hindgut where it can be fermented by resident microorganisms. Microbial fermentation of RS in the hindgut results in the production of short chain fatty acids(SCFA). Production of SCFA in turn results in growth and proliferation of colonic and cecal cells, increased expression of genes involved in gut development, and creation of an acidic environment. The acidic environment suppresses the growth of pathogenic microorganisms while selectively promoting the growth of beneficial microbes. Thus, RS has the potential to improve gut health and function by modifying and stabilising gut microbial community and by improving the immunological status of the host. In this review, we discussed the roles of RS in modifying and stabilising gut microbiota, gut health and function, carcass quality, and energy metabolism and growth performance in pigs and poultry.展开更多
Three high-temperature resistant polymeric additives for water-based drilling fluids are designed and developed:weakly cross-linked zwitterionic polymer fluid loss reducer(WCZ),flexible polymer microsphere nano-pluggi...Three high-temperature resistant polymeric additives for water-based drilling fluids are designed and developed:weakly cross-linked zwitterionic polymer fluid loss reducer(WCZ),flexible polymer microsphere nano-plugging agent(FPM)and comb-structure polymeric lubricant(CSP).A high-temperature resistant and high-density polymeric saturated brine-based drilling fluid was developed for deep drilling.The WCZ has a good anti-polyelectrolyte effect and exhibits the API fluid loss less than 8 mL after aging in saturated salt environment at 200°C.The FPM can reduce the fluid loss by improving the quality of the mud cake and has a good plugging effect on nano-scale pores/fractures.The CSP,with a weight average molecular weight of 4804,has multiple polar adsorption sites and exhibits excellent lubricating performance under high temperature and high salt conditions.The developed drilling fluid system with a density of 2.0 g/cm^(3)has good rheological properties.It shows a fluid loss less than 15 mL at 200°C and high pressure,a sedimentation factor(SF)smaller than 0.52 after standing at high temperature for 5 d,and a rolling recovery of hydratable drill cuttings similar to oil-based drilling fluid.Besides,it has good plugging and lubricating performance.展开更多
In this paper,UR50 ultra-early-strength cement-based self-compacting high-strength concrete slabs(URCS)have been subjected to contact explosion tests with different TNT charge quality,aiming to evaluate the anti-explo...In this paper,UR50 ultra-early-strength cement-based self-compacting high-strength concrete slabs(URCS)have been subjected to contact explosion tests with different TNT charge quality,aiming to evaluate the anti-explosive performance of URCS.In the experiment,three kinds of ultra-early-strength cement-based reinforced concrete slabs with different reinforcement ratios and a normal concrete slab(NRCS)were used as the control specimen,the curing time of URCS is 28 days and 24 h respectively.The research results show that URCS has a stronger anti-explosion ability than NRCS.The failure mode of URCS under contact explosion is that the front of the reinforced concrete slab explodes into a crater,and the back is spall.With the increase of the charge,the failure mode of the reinforced concrete slab gradually changed to explosive penetration and explosive punching.The experiment results also show that the reinforcement ratio of URCS has little effect on the anti-blast performance,and URCS can reach its anti-blast performance at 28 days after curing for 24 h.On this basis,the damage parameters of URCS for different curing durations were quantified,and an empirical formula for predicting the diameter of the crater and spalling was established.展开更多
文摘The immediate post-weaning period poses a major challenge on the survival of piglets. Similarly, newly hatched chicks face life threatening challenges due to enteric infections. In the past several years, in-feed antibiotics have been used to reduce these production problems and improve growth. However, in-feed antibiotics have been banned in many jurisdictions and therefore the most effective alternatives to infeed antibiotics must be developed. To date, several studies have been conducted to develop alternatives to antibiotics. One of the potential candidates as alternatives to in-feed antibiotics is resistant starch(RS). Resistance starch is a type of starch that resists enzymatic digestion in the upper parts of the gastrointestinal tract and therefore passes to hindgut where it can be fermented by resident microorganisms. Microbial fermentation of RS in the hindgut results in the production of short chain fatty acids(SCFA). Production of SCFA in turn results in growth and proliferation of colonic and cecal cells, increased expression of genes involved in gut development, and creation of an acidic environment. The acidic environment suppresses the growth of pathogenic microorganisms while selectively promoting the growth of beneficial microbes. Thus, RS has the potential to improve gut health and function by modifying and stabilising gut microbial community and by improving the immunological status of the host. In this review, we discussed the roles of RS in modifying and stabilising gut microbiota, gut health and function, carcass quality, and energy metabolism and growth performance in pigs and poultry.
基金Supported by the National Natural Science Foundation of China(52288101).
文摘Three high-temperature resistant polymeric additives for water-based drilling fluids are designed and developed:weakly cross-linked zwitterionic polymer fluid loss reducer(WCZ),flexible polymer microsphere nano-plugging agent(FPM)and comb-structure polymeric lubricant(CSP).A high-temperature resistant and high-density polymeric saturated brine-based drilling fluid was developed for deep drilling.The WCZ has a good anti-polyelectrolyte effect and exhibits the API fluid loss less than 8 mL after aging in saturated salt environment at 200°C.The FPM can reduce the fluid loss by improving the quality of the mud cake and has a good plugging effect on nano-scale pores/fractures.The CSP,with a weight average molecular weight of 4804,has multiple polar adsorption sites and exhibits excellent lubricating performance under high temperature and high salt conditions.The developed drilling fluid system with a density of 2.0 g/cm^(3)has good rheological properties.It shows a fluid loss less than 15 mL at 200°C and high pressure,a sedimentation factor(SF)smaller than 0.52 after standing at high temperature for 5 d,and a rolling recovery of hydratable drill cuttings similar to oil-based drilling fluid.Besides,it has good plugging and lubricating performance.
基金financial support from National Natural Science Foundation of China(Grant No.11302261 and No.11972201)supported by the project of Key Laboratory of Impact and Safety Engineering(Ningbo University),Ministry of Education.The project number is CJ202011.
文摘In this paper,UR50 ultra-early-strength cement-based self-compacting high-strength concrete slabs(URCS)have been subjected to contact explosion tests with different TNT charge quality,aiming to evaluate the anti-explosive performance of URCS.In the experiment,three kinds of ultra-early-strength cement-based reinforced concrete slabs with different reinforcement ratios and a normal concrete slab(NRCS)were used as the control specimen,the curing time of URCS is 28 days and 24 h respectively.The research results show that URCS has a stronger anti-explosion ability than NRCS.The failure mode of URCS under contact explosion is that the front of the reinforced concrete slab explodes into a crater,and the back is spall.With the increase of the charge,the failure mode of the reinforced concrete slab gradually changed to explosive penetration and explosive punching.The experiment results also show that the reinforcement ratio of URCS has little effect on the anti-blast performance,and URCS can reach its anti-blast performance at 28 days after curing for 24 h.On this basis,the damage parameters of URCS for different curing durations were quantified,and an empirical formula for predicting the diameter of the crater and spalling was established.
