灰铸铁生产技术的一些新进展

对灰铸铁的研究现状和生产中的一些新技术做了评述。重点介绍了高强度薄壁灰铸铁的生产现状以及先进的制造工艺和先进的制造手段在灰铸铁生产中应用所取得的技术成果。     

Construction and Identification of Yeast Surface Display Libraries of Ovis aries DRA Gene Exon 2

The specific primers were designed according to Ovis aries DRA gene sequence deposited in GenBank and the multiple cloning site of the plasmid pYD1,which was a vector used for protein surface display on Saccharomyces cerevisiae.The gene encoding DRA was amplified by PCR using the genomic RNA of Ovis aries.The 762 bp fragment was cloned and released in GenBank and registration number was KR422362.The PCR product was inserted into the yeast surface display plasmid vector pYD1 by double enzyme digestion.It was indicated that DRA gene was successfully integrated into the genome.Dot mutation was made at both ends of exon 2 in DRA gene for making restriction enzyme cutting site and design the exon 2 specific primers according to mutated Ovis aries DRA gene sequence.Sequenced exon 2 amplification products based on DNA pooling of sheep large sample template was analyzed the polymorphic loci.The polymorphic exon 2 246 bp fragment was obtained by double enzyme digestion and connected to surface display restructuring mutation carriers pYD1-DRA by the same double enzyme digestion,and then we successfully constructed yeast surface display libraries.We transformed it into Saccharomyces cerevisiae EBY100 cell.Yeast monoclone was identified by PCR amplification and sequencing,and we confirmed that DRA gene had been integrated into Saccharomyces cerevisiae genome.After galactose induced,it was detected that DRA gene library had been successfully demonstrated on the yeast cell surface under the fluorescence microscope by immunofluorescence method.     

响应面法优化杜仲叶提取物的制备工艺

优化杜仲叶提取物制备的工艺条件,在单因素试验基础上,以杜仲叶提取物浸膏得率和绿原酸转移率为评价指标,采用Box-Behnken中心组合设计法优化杜仲叶提取物制备的工艺条件。杜仲叶提取物制备的最佳工艺条件为乙醇浓度500mL/L,液料比10∶1(mL/g),提取温度97℃,提取4次,每次30min;在此最佳工艺条件下,杜仲叶提取物浸膏得率和绿原酸转移率综合评分均值为99.08,与预测值基本一致。响应面法(RSM)优化的杜仲叶提取物制备工艺稳定可靠。     

Effects of Bacillus amylolyticus on Rumen Dry Matter Digestibility,Fermentation Parameters and Metabolites of Dairy Cows北大核心CSCD

This experiment was conducted to study the effects of Bacillus amylolyticus on rumen dry matter digestibility, fermentation parameters and metabolites of dairy cows. Experiment 1: six dairy cows with permanent fistula and had the similar parity (2 to 3 fetuses), body weight [(662 ±57) kg], lactation days [(160 ± 22) d] and milk yield [(36.1 ±3.8) kg / d], were randomly divided into 3 groups with 2 cows per group. Using 3 ×3 Latin square design, each group was extra fed 0 (control group), 5 ×109 and 5 ×1010 CFU / d Bacillus amylolyticus, the trial period was 3 periods, 13 days for each period, including 10 days for the pre-trial period and 3 days for the trial period. At the beginning of the trial period, the rumen dry matter digestibility of cows was measured by nylon bag method. Experiment 2: thirty dairy cows with similar parity [(2.5 ±0.3) fetuses], initial body weight [(559.2 ± 7. 4) kg], milk yield [(35. 2 ± 1. 5) kg / d] and lactation days [(99 ± 22) d] were randomly divided into three groups with 10 cows in each group. Cows in the 3 groups were extra fed with 0 (control group), 5 ×109 and 5 ×1010 CFU / d Bacillus amylolyticus, respectively. The pre-trial period was 10 days and the trial period was 42 days. The rumen fluid was collected on the last day of the trial period, and the rumen fermentation parameters and metabolites were determined. The results showed as follows: compared with the control group, 1) supplementary feeding of 5 × 1010 CFU / d Bacillus amylolyticus could significantly improve the rumen dry matter digestibility of dairy cows at 12, 24, 36, 48 and 72 h (P <0.05), supplementary feeding of 5 ×109 CFU / d Bacillus amylolyticus could significantly improve the rumen dry matter digestibility of dairy cows at 36 and 48 h (P <0.05); 2) supplementary feeding of 5 ×109 CFU / d Bacillus amylolyticus could significantly increase the contents of isobutyric acid, butyric acid, isovaleric acid, valeric acid, total volatile fatty acid and microbial protein in the rumen of dairy cows (P < 0. 05), supplementary feeding of 5 × 1010 CFU / d Bacillus amylolyticus could significantly increase the contents of isobutyric acid and isovaleric acid in the rumen of dairy cows and significantly reduce the rumen acetic acid / propionic acid (P < 0. 05), supplementary feeding of 5 ×109 and 5 ×1010 Bacillus amylolyticus had no effects on rumen pH and ammonia nitrogen content (P >0.05); 3) eleven metabolic pathways related to differential metabolites were detected, and ascorbic acid and alginate metabolism were significantly enriched (P < 0. 05) . In conclusion, Bacillus amylolyticus can increase the rumen dry matter digestibility, and improve the rumen fermentation function of dairy cows by affecting the content of rumen metabolites. By comprehensive analysis, supplementary feeding of 5 × 109 CFU / d Bacillus amylolyticus can achieve better effect. © 2023 Authors. All rights reserved.     

Effects of Compound Plant Nutrients on Rumen Fermentation Parameters,Rumen Microbiota and Fatty Acid Composition of Longissimus dorsi Muscle in Finishing Small Tail Han Sheep北大核心CSCD

This study was conducted to investigate the effects of compound p1ant nutrients (CPN) on rumen fermentation parameters, rumen microbiota and fatty acid composition of longissimus dorsi musc1e in finishing sma11 tai1 Han sheep. Sixteen 4-month-o1d finishing sma11 tai1 Han sheep with an initia1 body weight (BW) of (24.18±0.31) kg were random1y divided into two groups, name1y, with 8 rep1icates per group and 1 sheep per rep1icate. The sheep in the contro1 group were fed a basa1 diet, whereas the sheep of the contro1 group (CPN group) was fed the basa1 diet supp1ementation with 3‰ CPN. The experiment 1asted for 97 days after 7 days adaption. The resu1ts showed as fo11ows: compared with the contro1 group, 1) adding CPN decreased the concentration of ammonia nitrogen (NH3-N) (P<0.05); 2) CPN supp1ementation affected beta diversity of rumen microbiota; 3) the re1ative abundance of Acidobacteriota, Erysipe1otrichaceae_UCG-002, Lactobacillus, and Megasphaera were enhanced by adding CPN (P<0.05), whereas, the re1ative abundance of Bacteroidetes and Prevotella was 1ower (P<0.05); 4) the supp1ementation of CPN had no significant effect on fatty acid composition of longissimus dorsi musc1e of fattening sma11-tai1ed Han sheep (P>0.05); 5) the contents of tota1 MUFA, C18:1n9c, C14:1, C16:1, C18:2n6c, C18:3n3 and n-3PUFA in the longissimus dorsi musc1e were corre1ated with the re1ative abundance of Megasphaera, Erysipe1otrichaceae_UCG-002, Succiniclasticum and Ruminococcus (P<0.05). In conc1usion, CPN can regu1ate the rumen microbiota structure and reduce the rumen NH3-N concentration of fattening sma11-tai1ed Han sheep. In production practice, CPN can be used as a rumen eco1ogica1 regu1ator. © 2023 Authors. All rights reserved.