Composition,function,and timing:exploring the early‑life gut microbiota in piglets for probiotic interventions

Background The establishment of a robust gut microbiota in piglets during their early developmental stage holds the potential for long-term advantageous effects.However,the optimal timeframe for introducing probiotics to achieve this outcome remains uncertain.Results In the context of this investigation,we conducted a longitudinal assessment of the fecal microbiota of 63 piglets at three distinct pre-weaning time points.Simultaneously,we gathered vaginal and fecal samples from 23 sows.Employing 16S rRNA gene and metagenomic sequencing methodologies,we conducted a comprehensive analysis of the fluctuation patterns in microbial composition,functional capacity,interaction networks,and colonization resistance within the gut microbiota of piglets.As the piglets progressed in age,discernible modifications in intestinal microbial diversity,composition,and function were observed.A source-tracking analysis unveiled the pivotal role of fecal and vaginal microbiota derived from sows in populating the gut microbiota of neonatal piglets.By D21,the microbial interaction network displayed a more concise and efficient configuration,accompanied by enhanced colonization resistance relative to the other two time points.Moreover,we identified three strains of Ruminococcus sp.at D10 as potential candidates for improving piglets’weight gain during the weaning phase.Conclusions The findings of this study propose that D10 represents the most opportune juncture for the introduction of external probiotic interventions during the early stages of piglet development.This investigation augments our comprehension of the microbiota dynamics in early-life of piglets and offers valuable insights for guiding forthcoming probiotic interventions.

Improving tensile-shear properties of friction stir lap welded dissimilar Al/Mg joints by eliminating hook defect and controlling interfacial reaction

To improve tensile-shear properties of fiction stir lap welded(FSLW) dissimilar Al/Mg joints, pin-tip profiles were innovatively designed and welding speed was optimized, and effects of them on formation, interface microstructure and mechanical properties of different FSLW joints were investigated. With increasing the welding speed, the tensile-shear load of FSLW joints produced by three pins presents an increasing firstly and then decreasing trend. Compared with Rpin, the hook and hole defect in the joints made by S-pin and T-pin are eliminated owing to additional eccentric force. Moreover, the joints obtained by T-pin at 75 mm/min have the highest tensile-shear load, and a maximum value of 3.425 kN is produced, which increases by 96.8%.Meanwhile, the pin-tip profile improves significantly the interface reaction depending on the welding temperature. For R-pin, thick brittle intermetallic compounds of about 6.9 μm Al3Mg2and 13.3 μm Al12Mg17layers at the welding interface derived from diffusion reaction are formed, resulting in continuous cracks. However, using T-pin can raise the interface temperature, and which makes the interface liquefy locally to generate only 2.2 μm Al3Mg2layer and dispersive(Al12-Mg17+Mg) eutectic structure. This can release high residual stress and remove welding crack, consequently enhancing the interface properties of T-pin joints.

Process-microstructure-properties of CuAlNi shape memory alloys fabricated by laser powder bed fusion

Cu-based shape memory alloys(SMAs)show great potential in the application of high temperature,but their performance improvement combining with additive manufacturing is still challenging.In this paper,nearly defect-free(99.7%relative density)CuAlNi SMAs with two types of thermal-induced martensites,18R and 2H,were successfully fabricated by laser powder bed fusion(LPBF).The remelting printing strat-egy with systematic optimization framework including densification and printability analysis was used to get optimal process window.The twin-related self-accommodation structure with long period stacking order substructure was formed during additive manufacturing process.The as-build samples show excel-lent mechanical properties(ultimate compressive strength of 1593±10 MPa and large fracture strain of 23.0%±0.1%)with double-yielding,and outstanding shape memory effect,with maximum recoverable strain of 3.39% and nearly 100%recovery rate under compressive strain not exceeding 6%.Furthermore,the microstructural evolution in LPBF involving remelting,martensitic transformation,and 2H marten-site was discussed.This result not only builds the microstructure framework involving high reflectivity alloys and martensitic transformation but also provides insight into the applicability of LPBF process in producing Cu-based SMAs.

Deformation mechanism of Cu-Al-Ni shape memory alloys fabricated via laser powder b e d fusion:Tension-compression asymmetry

Introducing the unique advantage of additive manufacturing technology into copper-based shape memory alloys(SMAs)to fabricate high-performance alloys has garnered great attention in recent years,but the intrinsic relationships between microstructure and mechanical properties need to be further clarified.In this paper,the microstructural evolution of ternary CuAlNi SMAs fabricated by laser powder bed fusion(LPBF)under the tensile-compressive loading was investigated to determine the underlying mechanism of tension-compression asymmetry,that is,excellent compressive but poor tensile properties.Multiscale characterization of the different deformation stages revealed the numerous activated deformation mech-anism on the 18R martensite matrix.A twin-related transformation dominated the main plastic defor-mation process due to lower stacking faults energy and high-density pre-existing planer defects in the CuAlNi SMAs.Deformation twinning nucleated at prior austenite boundaries and developed into parallel and network structures inside the parent grain of different sizes.In addition,the preferred orientation in different stages,the stress-inducedγphase transformation,and the interaction between dislocations and stacking faults are discussed.These results not only provide significant insights to understand the detwinning and deformation twinning process of SMAs but also establish the essential framework of mi-crostructure and mechanical properties of Cu-based SMAs fabricated by LPBF.