纳米成型技术中的锚栓效应

纳米成型技术(NMT)是一种将聚合物直接注射于预先经纳米化处理的金属表面,使2种材料牢固结合的新技术。使用NMT制备的聚合物/金属一体化制品质量轻、界面强度高、结构稳定性好,近年来被广泛应用于智能手机、便携式电子器件等领域。文中系统介绍了NMT中金属表面纳米化处理方法、可用于NMT的金属和聚合物材料的种类及特点,以及注射成型加工中各项工艺参数的选择。结合受限态聚合物的研究成果,重点阐述了造成NMT制品高界面结合强度的锚栓效应的形成机理及失效机制。从NMT原理出发,在总结现有纳米成型技术相关成果的基础上,预测了NMT技术的未来发展趋势。

Cr-catalyzed allylic C(sp~3)–H addition to aldehydes enabled by photoinduced ligand-to-metal charge transfer

Photoinduced ligand-to-metal charge transfer(LMCT) has emerged as an effective strategy for synthesizing organic molecules in a sustainable manner. However, the majority of existing reports on selective C(sp~3)–H bond functionalization via photoinduced LMCT focus on the use of late transition metals or rare-earth metals for radical additions or cross-couplings. In contrast, the utilization of photoinduced LMCT with 3d early transition metals poses a significant challenge. Herein, we describe an unprecedented approach to allylic C(sp~3)–H addition to aldehydes, employing chromium(Cr) complexes as catalysts through visible-light-induced LMCT. By investigating the reaction pathway through various mechanistic studies, including radical trapping, kinetic isotope effect(KIE) analysis, and transient absorption spectroscopy, valuable insights have been gained. The proposed mechanism suggests the intermediacy of bromine radicals through homolysis of the Cr–Br bond. Notably, this protocol expands our understanding of the photochemical properties of earth-abundant Cr complexes.

N-Acetyl-D-glucosamine improves the intestinal development and nutrient absorption of weaned piglets via regulating the activity of intestinal stem cells

Early weaning in piglets can cause a series of negative effects.This causes serious losses to the livestock industry.N-Acetyl-D-glucosamine(D-GlcNAc)plays an important role in regulating the homeostasis of the intestine.This study aimed to investigate the effects of D-GlcNAc on the growth performance and intestinal function of weaned piglets.Twenty-four weaned piglets([Yorkshire×Landrace]Duroc,6.58±0.15 kg,n=8)at 21 d old were fed 3 diets supplemented with 0(control),1 and 3 g/kg D-GlcNAc.The intestinal organoid model was used to verify the regulatory mechanism of D-GlcNAc on intestinal epithelial cells.On the whole,supplementation of D-GlcNAc in the piglet diet has no significant effect on the growth performance and diarrhoea of weaned piglets(P>0.05).The apparent digestibility of nutrients and mRNA abundance of nutrient transporters in the 1 g/kg D-GlcNAc group were increased significantly(P<0.05).D-GlcNAc did not affect villus height(VH)and crypt depth(CD)but resulted in a numerically shorter VH and shallower CD,which lead to an increase in ileal VH:CD ratio(P<0.05).Cell shedding rates in the ileum villi increased(P<0.05).The relative length and weight of the small intestine of weaned piglets increased(P<0.05).In vitro studies found that the budding rates of organoids treated with 0.1 mmol/L D-GlcNAc increased on the d 3 and 5(P<0.05).The average budding numbers per budding organoid treated with 0.1 and 10 mmol/L D-GlcNAc increased on d 3(P<0.05).D-GlcNAc upregulated leucine rich repeat containing G protein-coupled receptor 5(Lgr5^(+))and Chromogranin A mRNA abundance in organoids(P<0.05).Mucin 2(Muc2)expression increased when treated with 1 and 10 mmol/L D-GlcNAc(P<0.05).In conclusion,dietary D-GlcNAc cannot improve the growth performance of weaned piglets.However,it can promote the growth and development of the intestinal tract and improve the digestion and absorption capacity of the intestine,which is achieved by affecting the activity of intestinal stem cells.

Dietary butyrate,lauric acid and stearic acid improve gut morphology and epithelial cell turnover in weaned piglets

This study was to evaluate the effects of the supplementation of saturated fatty acids with different chain lengths on growth performance,intestinal morphology,epithelial cell proliferation,differentiation and apoptosis in weaned piglets.Thirty-two weaned piglets(Duroc×Landrace×Yorkshire,BW=7.81±0.26 kg)were weaned at 21 d and randomly assigned to 1 of 4 experimental treatments:(1)a basal diet(control);(2)control+0.3% butyrate(BT);(3)control+0.3%lauric acid(LA);(4)control+0.3% stearic acid(SA).All piglets were then slaughtered for tissue sampling after having been fed experimental diets for 28 d after weaning.Supplementation of BT increased the gain-to-feed ratio(G:F)(P<0.05)compared to piglets fed the control diet from 14 to 28 d.In addition,the villus height(VH)to crypt depth(CD)ratio(VH:CD ratio)of the ileum were higher in the BT and LA diets than that of the control diet(P<0.05).The SA-supplemented diet increased ileal VH(P<0.05),whereas the BT-supplemented diet increased jejunal CD(P<0.05).Compared to the control,diets supplemented with BT,LA,or SA all tended to increase jejunal proliferation(Ki67/crypt positive cells)(P=0.190);diets supplemented with BT or SA significantly increased the number of ki67-positive cells in the ileal crypt(P<0.05).Furthermore,in the jejunum,the protein expression of activated caspase 3 and villin were increased in piglets fed BT,LA,or SA diets compared to those on the control diet(P<0.05).In the ileum,compared with the control diet,the BT diet tended to increase the protein level of mammalian phosphorylation target of rapamycin(p-m TOR,P<0.10);LA or SA diets significantly increased p-m TOR protein expression(P<0.05).These results show that dietary supplementation of BT,LA,or SA promotes jejunal cell renewal in weaned piglets.At the same time,increased proliferation of ileal crypt cells by promoting p-m TOR expression has beneficial effects on ileal morphology in weaned piglets.