Effects of Xylo-Oligosaccharides on Growth and Gut Microbiota as Potential Replacements for Antibiotic in Weaning Piglets.

Xylo-oligosaccharides (XOS) is a well-known kind of oligosaccharide and extensively applied as a prebiotic. The objective of this study was to investigate the effect of XOS supplementation substituting chlortetracycline (CTC) on growth, gut morphology, gut microbiota, and hindgut short chain fatty acid (SCFA) contents of weaning piglets. A total of 180 weaned piglets were randomly allocated to three treatments for 28 days, as follows: control group (basal diet, CON), basal diet with 500 mg/kg (XOS500) XOS, and positive control (basal diet with 100 mg/kg CTC). Compared with the CON group, the piglets in the XOS500 group improved body weight (BW) on days 28, average daily gain (ADG) and reduced feed: gain ratio during days 1-28 (P < 0.05). The XOS500 supplementation increased Villus height and Villus height: Crypt depth ratio in the ileum (P < 0.05). Villus Height: Crypt Depth of the ileum was also increased in the CTC treatment group (P < 0.05). Meanwhile, the XOS500 supplementation increased significantly the numbers of goblet cells in the crypt of the cecum. High-throughput 16S rRNA gene sequencing revealed distinct differences in microbial compositions between the ileum and cecum. XOS500 supplementation significantly increased the bacterial diversity. However, CTC treatment markedly reduced the microbial diversity (P < 0.05). Meanwhile, XOS500 supplementation in the diet significantly increased the abundance of Lactobacillus genus compared to the CON and CTC group in the ileum and cecum (P < 0.01), whereas the level of Clostridium_sensu_stricto_1, Escherichia-Shigella, and Terrisporobacter genus in the XOS500 group were markedly lower than the CON and CTC group (P < 0.05). In addition, dietary supplementation with XOS500 significantly increased the total short-chain fatty acids, propionate and butyrate concentrations and decreased the acetate concentration compared to the CON group in the cecum (P < 0.05). In summary, dietary supplemented with XOS500 could enhance specific beneficial microbiota abundance and decrease harmful microbiota abundance to maintain the structure of the intestinal morphology and improve growth performance of weaned piglets. Thus, XOS may potentially function as an alternative to in-feed antibiotics in weaned piglets in modern husbandry

Impacts of Tree Canopy Cover on Microclimate and Human Thermal Comfort in a Shallow Street Canyon in Wuhan, China

Increasing the number of street trees can be a promising method to reduce impacts of climate change currently impacting urban public health. However, the quantitative relationships between tree canopy cover and thermal comfort remains unclear, particularly in areas with high temperature and high humidity. This study aims to provide a better understanding of the effects of different degrees of tree canopy cover on human thermal comfort in shallow street canyons in a high temperature, high humidity area of China. Microclimatic measurements and qualitative surveys were conducted on sunny summer days in a shallow street canyon in Wuhan. The results suggest that microclimate benefits are greater for areas with a high-percentage tree canopy cover compared to medium- and low-percentage tree canopy cover&mdash;especially at noon. In streets with a high-percentage tree canopy cover, afternoon air temperatures and mean radiant temperatures can be reduced by up to 3.3 &deg;C and 13.9 &deg;C, respectively, compared to a similar street with no tree shade. The thermal sensation prediction formula is proposed and the relationship between human thermal sensation and microclimate factors is established. Blocking solar radiation and increasing wind speed are more feasible than controlling air temperature and humidity as ways to improve human thermal comfort

Highly Syndioselective 3,4-<i>Trans</i> Polymerization of (<i>E</i>)‑1-(4-Methylphenyl)-1,3-butadiene by Fluorenyl <i>N</i>‑Heterocyclic Carbene Ligated Lutetium Bis(alkyl) Precursor

(<i>E</i>)-1-(4-Methylphenyl)-1,3-butadiene (E-1-MPBD) synthesized via the “Wittig-type” reaction was polymerized with the ternary catalytic system (Flu-NHC)­Lu­(CH₂SiMe₃)₂/Al^<i>i</i>Bu₃/[Ph₃C]­[B­(C₆F₅)₄] (Flu-NHC = C₁₃H₈CH₂CH₂(NCHCHN­(C₆H₂Me₃-2,4,6)­C) to afford a new product containing exclusively <i>trans</i>-3,4 (>99%) units with perfect syndiotacticity (<i>rrrr</i> > 99%). The regio-3,4 tacticity was proved by the IR and NMR (¹H and ¹³C) spectroscopic analyses, while the 3,4-stereotacticity was confirmed by a model polymer with lower regularity (3,4 = 90.9%, <i>rrrr</i> = 49.3%) prepared by the binary catalytic system (Am-NHC)­Lu­(CH₂SiMe₃)₂/[Ph₃C]­[B­(C₆F₅)₄] (Am-NHC = 2,6-^<i>i</i>PrC₆H₃NC­(C₆H₅)­NCH₂CH₂­(NCH­CHN­(C₆H₂Me₃-2,4,6)­C). The <i>trans</i>-planar conformation was uncovered through 2D-NOESY and ¹³C CPMAS NMR technologies. This represents the first stereo 3,4-syndioselective polymerization of 1,3-dienes achieved by a rare-earth metal based catalyst. Moreover, hydrogenating the resulting polymer gave the highly syndiotactic poly­(4-methylphenyl-1-butene), which cannot be achieved by any other manner at the present stage