The negative Poisson’s ratio(NPR)bolt is an innovative support element distinguished by its high strength,elongation,and a slightly negative Poisson’s ratio.Unlike conventional prestressed(PR)bolts with a positive P...The negative Poisson’s ratio(NPR)bolt is an innovative support element distinguished by its high strength,elongation,and a slightly negative Poisson’s ratio.Unlike conventional prestressed(PR)bolts with a positive Poisson’s ratio,the NPR bolt exhibits a quasi-ideal plastic response without a prominent yield platform,enabling it to sustain high prestress with a substantial safety margin,which is particularly advantageous for jointed rock masses.However,investigations into the shear resistance mechanisms of NPR bolts under varying prestress levels remain limited.This study conducted full-scale double shear tests to assess the shear strength,deformation behavior,energy absorption,and failure mechanisms of NPR bolts under different prestress conditions.To ensure a fair comparison with PR bolts,a prestress utilization coefficient(PUC)was introduced.The results reveal that at a PUC of 0.25,the NPR bolt achieved peak axial force,shear displacement,and peak shear force values that are 2.41,1.88,and 2.13 times greater than those of the PR bolt,respectively.Shear performance was optimized at a prestress level of 100 kN,with energy absorption reaching 47.1 kJ,which is 2.8 times that of the PR bolt.Furthermore,the necking ratio was significantly reduced,indicating more distributed plastic deformation and delayed failure.Field applications verified the superior performance,resulting in a 27.4%reduction in roof settlement and enhanced structural integrity.These findings confirm that NPR bolts possess excellent shear resistance,energy absorption,and deformation adaptability,and optimizing prestress significantly enhances their support performance,providing a strong basis for geotechnical engineering applications.展开更多
NOx sensors, as a core component of diesel engine exhaust treatment system, play an important role in exhaust emission control, which can accurately and quickly detect the NOx and O2 concentration. It has become a nec...NOx sensors, as a core component of diesel engine exhaust treatment system, play an important role in exhaust emission control, which can accurately and quickly detect the NOx and O2 concentration. It has become a necessary option for the detection of existing exhaust emission standards. At present, there is limited and scattered information on knowledge and test methods of NOx sensors, the research of NOx sensors has become a challenging research topic at home and abroad. Based on these requirements, the article systematically integrates the knowledge of principle and testing methods. First of all, through introducing functional description of NOx sensors and the basic principle of NOx sensors, the relevant scholars can have an overall understanding of the product and master the operation mode of products. Secondly, the current status of performance test bench and methods of NOx sensors were described, which can contribute to having a clear understanding of the development process. After that, a new structure of NOx sensors test bench was purposed, which contains six major units including standard gas source, gas mixing unit, analyzer measurement unit, sensor measurement unit, data processing and display unit, exhaust gas treatment unit. And the test bench was validated. The experimental results show that the test bench has the advantages of high-repeatability, high reliability and low cost. And it can realize automatic detection of multiple target values, which is worthy further promotion. Thereby, the article can contribute to the development of its technology indirectly.展开更多
Four types of Mg-5Zn porous scaffolds with different pore geometries,including body-centered cubic(bcc),the rhombic dodecahedron(RD),gyroid(G),and primitive(P)types,were designed and fabricated using selective laser m...Four types of Mg-5Zn porous scaffolds with different pore geometries,including body-centered cubic(bcc),the rhombic dodecahedron(RD),gyroid(G),and primitive(P)types,were designed and fabricated using selective laser melting.Their forming quality,compression mechanical properties,and degradation behavior were investigated.Results indicate that the fabricated scaffolds exhibit good dimensional accuracy,and the surface chemical polishing treatment significantly improves the forming quality and reduces porosity error in porous scaffolds.Compared to the ones with rod structures(bcc,RD),the scaffolds with surface structures(G,P)have less powder particle adhesion.The G porous scaffold exhibits the best forming quality for the same design porosity.The predominant failure mode of scaffolds during compression is a 45°shear fracture.At a porosity of 75%,the compression property of all scaffolds meets the compressive property requirements of cancellous bone,while bcc and G structures show relatively better compression property.After immersion in Hank's solution for 168 h,the B-2-75% pore structure scaffold exhibits severe localized corrosion,with fractures in partial pillar connections.In contrast,the G-3-75% pore structure scaffold mainly undergoes uniform corrosion,maintaining structural integrity,and its corrosion rate and loss of compressive properties are less than those of the B-2-75%structure.After comparison,the G-pore structure scaffold is preferred.展开更多
Background: The study’s primary research suggests the relationship between high-school international students in China’s sleep quality and learning efficiency which is academic performance. Considering the effect of...Background: The study’s primary research suggests the relationship between high-school international students in China’s sleep quality and learning efficiency which is academic performance. Considering the effect of Chinese traditional cultural background, this study mainly investigates Chinese international high school students’ sleeping quality and patterns through the Pittsburgh Sleep Quality Index. Methods: A sample of 249 Chinese high school students in the Pearl River Region completed the questionnaire about their sleep quality using PSQI, their academic performance, and socio-demographic factors one month before the final exam in July 2023. Results: None of the students have good sleep quality, according to the PSQI;40.8% of students have poor sleep quality, and 59.2% have significant sleep disturbance. The results of ordinal logistic regression show that good sleep quality is positively associated with good academic performance. Conclusion: Our findings highlight the association between sleep and academic performance on the unique sleep patterns of Chinese international high school students, who often follow very different sleep patterns from other conventional students enrolled in the regular curriculum. High school students suffer from severe sleep deprivation and poor sleep quality. Under great academic stress, Chinese high school students should know the importance of sleep, balance sleep, and study.展开更多
This study investigated the differences between children with and without learning difficulties(LD)regarding academic performance(AP)and sleep quality(SLQ).A total of 1,501 children were evaluated,including 810 with L...This study investigated the differences between children with and without learning difficulties(LD)regarding academic performance(AP)and sleep quality(SLQ).A total of 1,501 children were evaluated,including 810 with LD and 691 without LD.The results indicated that children with LD scored significantly lower in AP and had poorer sleep quality,with greater variability in SLQ patterns.Correlation analysis revealed a significant negative association between sleep quality and academic performance(r=-0.646;p<0.01),indicating that poorer sleep quality is related to lower academic performance.These findings underscore the importance of interventions focused on promoting sleep hygiene and consistent routines to mitigate the negative impacts of learning difficulties.Study limitations include the absence of mediating variables,such as screen time and mental health,suggesting the need for future research exploring longitudinal interventions and associated factors.展开更多
Glycerol mono laurate(GML)has been widely used as an effective antibacterial emulsifier in the food in?dustry.A total of 360 44-week-old Hy-Line brown laying hens were randomly distributed into four groups each with s...Glycerol mono laurate(GML)has been widely used as an effective antibacterial emulsifier in the food in?dustry.A total of 360 44-week-old Hy-Line brown laying hens were randomly distributed into four groups each with six replicates of 15 birds,and fed with com-soybean-meal-based diets supplemented with 0,0.15,0.30,and 0.45 g/kg GML,respectively.Our results showed that 0.15,0.30,and 0.45 g/kg GML treatments significantly decreased feed conversion ratios(FCRs)by 2.65%,7.08%,and 3.54%,respectively,and significantly increased the laying rates and average egg weights.For egg quality,GML drastically in creased albume n height and Haugh units,and enhanced yolk color.Notably,GML increased the concentrations of polyunsaturated and monounsaturated fatty acids and reduced the concentration of total saturated fatty acids in the yolk.The albumen composition was also significantly modified,with an increase of 1.02%in total protein content,and increased 8ntents of His(4.55%)and Glu(2.02%)under the 0.30 g/kg GML treatment.Additionally,GML treatments had positive effects on the lipid metabolism of laying hens,including lowering the serum triglyceride and total cholesterol levels and reducing fat deposit!on in abdominal adipose tissue.Intestinal morphology was also improved by GML treatment,with increased villus length and villus height to crypt depth ratio.Our data demonstrated that GML supplementation of laying hens could have beneficial effects on both their productivity and physiological properties,which indicates the potential application of GML as a functional feed additive and gives us a new in sight into this traditional food additive.展开更多
[Objective]The paper was to study the effects of xylooligosaccharide(XOS)and probiotics(PRO)and their interaction on the production performance,egg quality and intestinal short-chain fatty acids of laying hens in late...[Objective]The paper was to study the effects of xylooligosaccharide(XOS)and probiotics(PRO)and their interaction on the production performance,egg quality and intestinal short-chain fatty acids of laying hens in late laying period.[Method]A total of 36074-week-old Romain brown laying hens were randomly divided into four groups,six replicates each group and 15 chickens each replicate.The trial lasted 63 d.The laying hens in control group(CON)were fed with basal diet,and those in experimental groups were fed with the basal diets adding with 150 mg/kg XOS(XOS group),100 mg/kg probiotics(PRO group),150 mg/kg XOS+100 mg/kg probiotics(XOS-PRO group).[Result]Compared with the control group,the laying rate,daily egg production,yolk ratio,colonic acetic acid and caecal propionic acid in XOS group increased significantly(P<0.05),and the feed gain ratio decreased remarkably(P<0.05).PRO had no significant effect on the production performance and egg quality of laying hens in late laying period(P>0.05),but significantly increased colonic acetic acid(P<0.05).XOS and PRO had no interaction effect on the production performance,egg quality and intestinal short-chain fatty acids of laying hens in late laying period(P<0.05).[Conclusion]Adding XOS to the diet of laying hens in late laying period could increase the content of short-chain fatty acids in the hindgut of laying hens,and effectively improve the production performance and egg quality of laying hens in late laying period.Adding PRO to the diet did not significantly improve the production performance and egg quality of laying hens,and there was no interaction effect between XOS and PRO.展开更多
To determine whether dried fermented ginger (DFG), fermented with Japanese mugwort silage juice, could be replaced by fermented corncob powder (FCP) as a of feed ingredient source without significant body weight decre...To determine whether dried fermented ginger (DFG), fermented with Japanese mugwort silage juice, could be replaced by fermented corncob powder (FCP) as a of feed ingredient source without significant body weight decrease or damage to visceral organs (using gross anatomical observation), to intestinal villi (using light microscopy), or to the epithelial cells on the villus apical surface (using scanning electron microscopy) the following investigation was performed. Sixty-four male broilers were allotted to 4 groups: a basal diet group (control group), and basal diet groups with DFG at a level of 50 ppm;with DFG at 50 ppm and FCP at 250 ppm (50 ppm DFG + 250 ppm FCP group);and with FCP at a level of 500 ppm (500 ppm FCP group). Feed intake, body weight gain, feed efficiency, carcass quality, small intestinal length and weight, and visceral organ weight were not different among groups. Furthermore, regarding intestinal villus height, villus area and crypt depth, a significant difference was not found among the groups. When these values of the control were expressed as an index of 100, the duodenal villus height of the 50 ppm DFG + 250 ppm FCP group and the 500 ppm FCP group were 114 and 119, respectively. The duodenal villus area of the 50 ppm DFG + 250 ppm FCP group and the 500 ppm FCP group were 125 and 158, respectively. These villus heights and areas are thought to be activated. On the epithelial cells on the villus apical surface in the duodenum and jejunum, the 50 ppm DFG + 250 ppm FCP group had protuberated cells into the intestinal lumen and deeper cells at the sites of recently exfoliated cells, suggesting that these cells are activated. The present results indicate that small amounts of fermented corncob powder can be used as a feed supplement when mixed with fermented ginger powder, due to the synergy between the two ingredients, resulting in a 6% increase in body weight gain。展开更多
This study aimed to investigate the effects of fermented puffed feather meal(FPFM)on growth performance,serum biochemical indices,meat quality,and intestinal microbiota in Arbor Acres(AA)broilers.A single-factor desig...This study aimed to investigate the effects of fermented puffed feather meal(FPFM)on growth performance,serum biochemical indices,meat quality,and intestinal microbiota in Arbor Acres(AA)broilers.A single-factor design was adopted,and four treatments were administered with five replicates to 240 one-day-old AA broilers.The control group(group A)received a basal diet,while the experimental groups received a basal diet plus 33%(group B),67%(group C)and 100%(group D)FPFM,respectively.Compared with group A,(1)the average daily gain(ADG)in group C decreased(P<0.05),and the feed conversion ratio(FCR)in group D increased(P<0.05);(2)the level of serum urea nitrogen in treatment groups decreased(P<0.05),and the levels of triglyceride,high density lipoprotein,low density lipoprotein,cholesterol,and glucose contents in group D increased(P<0.05)at day 21;(3)the serum immunoglobulin M and immunoglobulin G in group B and the immunoglobulin A in group C increased(P<0.05)at day 21,and the serum immunoglobulin M and immunoglobulin G in group D decreased(P<0.05)at day 42;(4)the share force of breast muscle and thigh muscle in group D increased(P<0.05);(5)the villus height to crypt depth ratio in the jejunum of group B increased(P<0.05)at day 21,and the villus height in group C and D increased(P<0.05)at day 42;(6)the proteobacteria counts in the cecum digesta in treatment groups decreased(P<0.05)at day 21.The basal diet supplemented with 33%FPFM promoted protein metabolism,enhanced immunity and improved meat quality,promoted the digestion and absorption of nutrients,increased intestinal microbial diversity,and improved the content of beneficial bacteria without affecting the growth performance,it was possible to be used as a good substitute for fish meal.展开更多
A heat transfer performance testing system is presented with its hardware structure, operation principle, and software control and measurement system. Working fluids of the subsystem include thermal conducting oil, co...A heat transfer performance testing system is presented with its hardware structure, operation principle, and software control and measurement system. Working fluids of the subsystem include thermal conducting oil, compressed air, glycol water solution and water as the heating fluids, and air and water as the cooling fluids. The heat transfer performance testing of heat exchangers can be conducted not only for a conventional one heating fluid to one cooling fluid, but also for a compound air cooling heat exchanger with two or three heating fluids in parallel or in series. The control and measurement system is implemented based on a LabVIEW software platform, consisting of the data acquisition and process system, and the automotive operation and control system. By using advanced measuring instruments combined with sound computer software control, the testing system has characteristics of a compact structure, high accuracy, a wide range of testing scope and a friendly operation interface. The uncertainty of the total heat transfer coefficient K is less than 5%. The testing system provides a reliable performance testing platform for designing and developing new heat exchangers.展开更多
In this paper, Duroc-lanndrae-Yorkshire crossbred piggy of born at 75 days of age, bouncing with health and similar body weight were randomly divided into experimental group （136 pigs） and control group （136 pigs）...In this paper, Duroc-lanndrae-Yorkshire crossbred piggy of born at 75 days of age, bouncing with health and similar body weight were randomly divided into experimental group （136 pigs） and control group （136 pigs）. Pigs in control group were fed with conventional diets, and 4% microbial fermentation feeds were added to the basal diet of experimental group to research on the effect of performance and meat quality of pig breeding. The results indicated that after feeding 106 d, compared to control group, the slaughter performance, meat quality and content of fatty acid and amino acid of experimental group were all better, its slaughter rate increased 1.53%, the carcass weight increased 2.75% and the backfat thickness decreased 0.02 cm. In addition, the pork meat in test group hadn＇t antibiotic and heavy metal residues, while it had higher color score, lower pH45min and pH24h value, better tenderness and rate of cooked meat and higher content of fatty acids, polyunsaturated fatty acids and amino acids. Microbial fermentation feed using in test group can significantly improved the flavor and aroma of pork, and eating this pork conducive more to human health. Thus, the application of microbial fermenta- tion feed can provide a more safe, healthy and nutritious flavor pork for human beings.展开更多
To realize automatic control of automobile transmission performance test stand Methods The automatic control technique of the lubricant temperature,the program- controll- edautomaticshifting of the transmission,the c...To realize automatic control of automobile transmission performance test stand Methods The automatic control technique of the lubricant temperature,the program- controll- edautomaticshifting of the transmission,the continuous adjusting of revolution speed and load, data-acquisition and data real-time processing were adopted.Results The lubricant temperature was controlled at the set temperature ±2℃.The automatic shifting of the trans- mission is simple,reliable and accurate.The automatic adjusting of load and rotation speed is rapidandaccurate,the torque divergence is ±1N·m,the rotation speed divergence is ±5r/min Conclusion The four kinds of techniques are applied into the automobile transmission perfor- mance test stand successfully. mancetest stand successfully.展开更多
[Objective]This study aimed to evaluate the meat quality of frizzle Chick-en, and to find out the correlation between the meat quality and slaughter perfor-mance. [Method] The slaughter performance such as live chicke...[Objective]This study aimed to evaluate the meat quality of frizzle Chick-en, and to find out the correlation between the meat quality and slaughter perfor-mance. [Method] The slaughter performance such as live chicken weight, carcass weight, semi-eviscerated weight, eviscerated weight, chest muscle weight, leg mus-cle weight, abdominal fat weight and the meat quality indices like color, pH and shear force of 12-week-old frizzle chickens were measured to analyze the correla-tion between slaughter performance and meat quality. [Result] The carcass percent-age, semi-eviscerated percentage, eviscerated percentage, chest muscle percentage, leg muscle percentage, abdominal fat percentage, intramuscular fat width and subcu-taneous fat thickness of the male chickens were 89.76%, 81.54%, 67.53%, 7.82%, 11.29%, 2.42%, 0.69 cm and 0.48 cm, of female chickens were 89.78%, 80.87%, 62.94%, 6.19%, 9.92%, 3.91%, 0.78 cm and 0.61 cm. Some of these traits exhibit-ed significant difference between the male and female chickens （P〈0.05）. In male chickens, the chest muscle color, pH and shear force were 5.93, 6.15 and 3.72 kg, and the leg muscle color, pH and shear force were 6.18, 6.54 and 3.41 kg; in fe-male chickens, the chest muscle color, pH and shear force were 5.77, 6.05 and 3.41 kg, and the leg muscle color, pH and shear force were 6.03, 6.21 and 2.74 kg. The quality of chest and leg muscles of frizzle chickens significantly differed （P〈0.05）. Carcass weight had significant positive correlations with semi-eviscerated weight and meat color （P〈0.05）, and an extremely significant positive correlation with pH （P〈0.01）. Semi-eviscerated weight and pH value shared a significant posi-tive correlation （P〈0.05）. Eviscerated weight and leg muscle weight shared an ex-tremely significant negative correlation （P〈0.01）. Abdominal fat weight correlated sig-nificantly and negatively with shear force （P〈0.05）. Meat color and pH value had a significant positive correlation （P〈0.05）. [Conclusion] This study provides theoretical basis for the breeding of excellent chicken varieties producing high-quality meat.展开更多
This study aimed to study the germplasm characteristics of Tibetan goat distributed in Sichuan. Three male and three female goats of twelve-month-old Ti-betan goat were selected, and they were slaughtered for analysis...This study aimed to study the germplasm characteristics of Tibetan goat distributed in Sichuan. Three male and three female goats of twelve-month-old Ti-betan goat were selected, and they were slaughtered for analysis of slaughter per-formance, muscle quality and muscle nutrients. The results showed that the pre-slaughter body weights, dressing percentages, meat percentages and carcass meat production rates of male and female Tibetan goats were （14.33±1.53） and （12.50±2.18） kg, （42.11±5.26）% and （43.85±4.51）%, （31.34±3.36）% and （32.84±3.16）%, and （72.34±0.54）% and （72.30±0.78）%, respectively. There were smal differences in car-cass size, carcass segmentation, muscle fiber properties, muscle quality, muscle nu-tritional composition, muscle minerals contents and muscle heavy metals contents between male and female Tibetan goats. A total of 18 kinds of amino acids were detected in the muscle of male and female Tibetan goats. The EAA/TAA ratios and EAA/NEAA ratios of male and female Tibetan goats were （39.18＆#177;0.38）%and （38.70±0.72）%, and （64.31±1.03）% and （63.21±1.92）%, respectively.展开更多
[Objective] This study was conducted to understand goat germplasm char- acteristics. [Method] With some 24-month-old males and females Tibet goats as experimental materials, a slaughter experiment was carried out to d...[Objective] This study was conducted to understand goat germplasm char- acteristics. [Method] With some 24-month-old males and females Tibet goats as experimental materials, a slaughter experiment was carried out to determine their slaughter performance, muscle quality and muscle nutritional components. [Result] The body weights of males and females before slaughter were （20.16±1.26） and （19.33±4.86） kg, respectively; the dressing percentages of males and females were （43.86±1.74）% and （44.08±5.46）%, respectively; the meat percentages were （32.43± 1.52）% and （32.72±3.97）%, respectively; and the meat production rates of carcass were （73.28±0.09）% and （73.16±0.85）%, respectively. There were less differences in carcass measurements, carcass segmentation, muscle quality, muscle fiber charac- teristics, muscle nutritional components, muscle mineral contents and heavy metal contents between males and females, while eye muscle area and hind leg meat weight of males were significantly higher than those of females. In muscles of males and females, 18 amino acids were detected totally, EAA/TAA values were （39.23±0.24）% and （38.70±0.15）%, respectively, and EAA/NEAA values were （64.73± 0.65）% and （63.17±0.41）%, respectively. [Conclusion] This study lays a foundation for overall understanding of germplasm characteristics of Tibetan goats.展开更多
[Objective] The aim was to discuss the resource characteristics of Danba goat. [Method] Three male and three female goats of twelve-month-old Danba goat were selected to slaughter,and their slaughter performance, musc...[Objective] The aim was to discuss the resource characteristics of Danba goat. [Method] Three male and three female goats of twelve-month-old Danba goat were selected to slaughter,and their slaughter performance, muscle qulity and mus- cle nutrients were determined. [Result] The pre-slaughter weights, dressing percent- ages, meat percentages and carcass meat production rates of the male and female Danba goats were （25.83±1.04） and （18.50±2.29） kg, （45.18±0.78）% and （38.89± 2.08）%, （33.76±1.4）% and （28.59±1.99）%, and （74.30±0.85）% and （74.08±0.65）%, respectively. The carcass length, carcass hind leg circumstance, carcass hind leg length, lumbar muscle thickness, hind leg meat yield, shoulder muscle yield and breast meat yield of male goats were significantly higher than those of female goats （P〈0.05）, and no significant differenceswere found in other carcass size and carcass segmentation indices between male and female goats （P〉0.05）. There were small differences in muscle fiber properties, muscle quality, muscle nutritional composition, muscle mineral content and muscle heavy metal content between male and female goats （P〈0.05）. A total of 18 kinds of amino acids were detected in the male and female goats. The EAA/TAAs and EANNEAAs of male and female goats were （39.56±0.26）% and （39.48±0.66）%, and （65.45±0.71）% and （65.43±1.80）%, respec- tively. [Conclusion] This study will provide the basis for the understanding of the resource characteristics of Danba goat.展开更多
Background： The protein/energy ratio is important for the production performance and utilization of available feed resources by animals. Increased protein consumption by mammals leads to elevated feed costs and incre...Background： The protein/energy ratio is important for the production performance and utilization of available feed resources by animals. Increased protein consumption by mammals leads to elevated feed costs and increased nitrogen release into the environment. This study aimed to evaluate the effects of dietary protein/energy ratio on the growth performance, carcass traits, meat quality, and plasma metabolites of pigs of different genotypes. Methods： Bama mini-pigs and Landrace pigs were randomly assigned to two dietary treatment groups （Chinese conventional diet with low protein/energy ratio or National Research Council diet with high protein/energy ratio; n = 24 per treatment） in a 2 x 2 factorial arrangement. Blood and muscle samples were collected at the end of the nursery, growing, and finishing phases. Results： We observed significant interactions （P 〈 0.05） between breed and diet for total fat percentage, intramuscular fat （IMF） content, protein content in biceps femoris （BF） muscle, and plasma urea nitrogen （UN） concentration in the nursery phase; for average daily gain （ADG）, average daily feed intake （ADFI）, dry matter, IMF content in psoas major （PM） muscle, and plasma total protein and albumin concentrations in the growing phase; and for drip loss and plasma UN concentration in the finishing phase. Breed influenced （P 〈 0.05） growth performance, carcass traits, and meat quality, but not plasma metabolites. Throughout the trial, Landrace pigs showed significantly higher （P 〈 0.0_5） ADG, ADFI, dressing percentage, lean mass rate, and loin-eye area than did Bama mini-pigs, but significantly lower （P 〈 0.0.5） feed/gain ratio, fat percentage, backfat thickness, and IMF content. Dietary protein/energy ratio influenced the pH value, chemical composition of BF and PM muscles, and plasma activities of glutamic-pyruvic transaminase and gamma-glutamyl transpeptidase, and plasma concentration of UN. Conclusions： Compared with Landrace pigs, Bama mini-pigs showed slower growth and lower carcass performance, but had better meat quality. Moreover, unlike Landrace pigs, the dietary protein/energy ratio did not affect the growth performance of Bama mini-pigs. These results suggest that, in swine production, low dietary protein/energy ratio may be useful for reducing feed costs and minimizing the adverse effects of ammonia release into the environment.展开更多
PM2.5 separator directly affects the accuracy of PM2.5 sampling.The specification testing and evaluation for PM2.5 separator is particularly important,especially under China’s wide variation of terrain and climate.In...PM2.5 separator directly affects the accuracy of PM2.5 sampling.The specification testing and evaluation for PM2.5 separator is particularly important,especially under China’s wide variation of terrain and climate.In this study,first a static test apparatus based on polydisperse aerosol was established and calibrated to evaluate the performance of the PM2.5 separators.A uniform mixing chamber was developed to make particles mix completely.The aerosol concentration relative standard deviations of three test points at the same horizontal chamber position were less than 0.57%,and the particle size distribution obeyed logarithmic normal distribution with an R2 of 0.996.The flow rate deviation between the measurement and the set point flow rate agreed to within±1.0%in the range of-40 to 50℃.Secondly,the separation,flow and loading characteristics of three cyclone separators(VSCC-A,SCC-A and SCC112)were evaluated using this system.The results showed that the 50%cutoff sizes(D50)of the three cyclones were 2.48,2.47 and 2.44μm when worked at the manufacturer’s recommended flow rates,respectively.The geometric standard deviation(GSD)of the capture efficiency of VSCCA was 1.23,showed a slightly sharper than SCC-A(GSD=1.27),while the SCC112 did not meet the relevant indicator(GSD=1.2±0.1)with a GSD=1.44.The flow rate and loading test had a great effect on D50,while the GSD remained almost the same as before.In addition,the maintenance frequency under different air pollution conditions of the cyclones was summarized according to the loading test.展开更多
Two experiments were conducted to in- vestigate the effects of net energy （NE） level on the performance and carcass traits of finishing pigs fed low crude protein （CP） diets supplemented with crystalline amino aci...Two experiments were conducted to in- vestigate the effects of net energy （NE） level on the performance and carcass traits of finishing pigs fed low crude protein （CP） diets supplemented with crystalline amino acids （CAA）. A total of 216 （Exp. 1） and 360 （Exp. 2 ） barrows （ Yorkshire × Landrace× Duroc ） were allotted to one of six treatments （n =6）. The experimental diets were based on corn and soybean meal, and consisted of a high-CP diet that contained approximately 16% CP and 2.50 Mcal/kg of NE as well as five low-CP diets in which the CP level of the diet was reduced by approximately four percentage units but was supplemented with crystalline lysine, methionine, threonine, and tryptophan. The low CP diets provided 2.64, 2.58, 2.50, 2.42, or 2.36 Mcal/kg in Exp. 1 as well as 2.45, 2.40, 2.35, 2.30, or 2.25 Mcai/kg in Exp.2. In Exp. 1, a linear （P=0.03） increase in weight gain was observed with decreasing NE level while the ratio of gain to feed was unaffect- ed （P 〉 0.05） by NE level. There was a linear in-crease （P = 0.01 ） in the percentage of fat-free lean and a linear decrease （ P = 0.03 ） in the percentage of total fat with decreasing NE levels. In Exp. 2, a sig- nificant quadratic （ P = 0.03 ） effect of NE level was observed for weight gain. The ratio of gain to feed demonstrated a significant （P 〈0.01 ） quadratic effect with pigs fed 2.35 and 2.40 Mcal/kg of NE, Pigs fed the diet containing 2.40 Mcal/kg of NE had the lowest percentage of total fat （36. 95% ） and the highest percentage of fat-free lean （49.36%）. The overall results of these experiments indicate that feed- ing either a surplus or a deficiency of NE is detrimen- tal to both pig performance and carcass composition when low CP diets supplemented with CAA are fed. Our results indicate that when the CP content of the diet is reduced by four percentage units and the diet is properly supplemented with CAA, maximum per- formance and carcass quality will be obtained if the diet provides approximately 2.42 Mcal/kg of NE.展开更多
Background： Highly automated cage-rearing systems are becoming increasingly popular in China. However, a high stocking density can cause oxidative stress and decrease broiler performance. The tryptophan （TRP） deriv...Background： Highly automated cage-rearing systems are becoming increasingly popular in China. However, a high stocking density can cause oxidative stress and decrease broiler performance. The tryptophan （TRP） derivative 5-hydroxytryptophan （5-HT） has been shown to preserve membrane fluidity in birds suffering from oxidative stress Therefore, this experiment was conducted to determine the effects of dietan/TRP supplementation on performance, breast meat quality and oxidative stress in broilers reared in cages with a high or low stocking density. Methods： Female Arbor Acres broilers （25-d-old, n = 144） were randomly allocated to 1 of 4 treatments. The birds were fed a diet based on corn, soybean meal, cottonseed meal and corn gluten meal containing either 0.18 or 0.27% TRP and were housed with stocking densities of 11 or 15.4 birds/m2 in a 2 x 2 factorial experiment. Broiler performance was evaluated from d 25 to 42. Eight birds from each treatment were slaughtered on d 42 and plasma and breast muscle samples were collected to measure biochemical indices. Results： A higher stocking density tended to be associated with reduced weight gain （P 〈 0.10）, and significantly increased plasma glutamic-pyruvic transaminase （GPT） activity （P 〈 0.001）. Increased dietary TRP significantly reduced the activities of lactic dehydrogenase and GPT while increasing total cholesterol in the plasma （P 〈 0.01）, reducing drip loss of breast muscle （P 〈 0.10） and improving feed efficiency （P 〈 0.10）. Conclusions： An increase in dietary TRP, ].S-fold higher than the standard supplementation level, can alleviate oxidative stress as well as improve welfare and feed efficiency in broilers reared in cages with a high stocking density.展开更多
基金supported by the State Key Laboratory of Intelligent Construction and Healthy Operation and Maintenance of Deep Underground Engineering(Grant No.SDGZ2505)the Postdoctoral Fellowship Program of the China Postdoctoral Science Foundation(Grant No.GZB20250742)the General Program of the China Postdoctoral Science Foundation(Grant No.2025M773213).
文摘The negative Poisson’s ratio(NPR)bolt is an innovative support element distinguished by its high strength,elongation,and a slightly negative Poisson’s ratio.Unlike conventional prestressed(PR)bolts with a positive Poisson’s ratio,the NPR bolt exhibits a quasi-ideal plastic response without a prominent yield platform,enabling it to sustain high prestress with a substantial safety margin,which is particularly advantageous for jointed rock masses.However,investigations into the shear resistance mechanisms of NPR bolts under varying prestress levels remain limited.This study conducted full-scale double shear tests to assess the shear strength,deformation behavior,energy absorption,and failure mechanisms of NPR bolts under different prestress conditions.To ensure a fair comparison with PR bolts,a prestress utilization coefficient(PUC)was introduced.The results reveal that at a PUC of 0.25,the NPR bolt achieved peak axial force,shear displacement,and peak shear force values that are 2.41,1.88,and 2.13 times greater than those of the PR bolt,respectively.Shear performance was optimized at a prestress level of 100 kN,with energy absorption reaching 47.1 kJ,which is 2.8 times that of the PR bolt.Furthermore,the necking ratio was significantly reduced,indicating more distributed plastic deformation and delayed failure.Field applications verified the superior performance,resulting in a 27.4%reduction in roof settlement and enhanced structural integrity.These findings confirm that NPR bolts possess excellent shear resistance,energy absorption,and deformation adaptability,and optimizing prestress significantly enhances their support performance,providing a strong basis for geotechnical engineering applications.
文摘NOx sensors, as a core component of diesel engine exhaust treatment system, play an important role in exhaust emission control, which can accurately and quickly detect the NOx and O2 concentration. It has become a necessary option for the detection of existing exhaust emission standards. At present, there is limited and scattered information on knowledge and test methods of NOx sensors, the research of NOx sensors has become a challenging research topic at home and abroad. Based on these requirements, the article systematically integrates the knowledge of principle and testing methods. First of all, through introducing functional description of NOx sensors and the basic principle of NOx sensors, the relevant scholars can have an overall understanding of the product and master the operation mode of products. Secondly, the current status of performance test bench and methods of NOx sensors were described, which can contribute to having a clear understanding of the development process. After that, a new structure of NOx sensors test bench was purposed, which contains six major units including standard gas source, gas mixing unit, analyzer measurement unit, sensor measurement unit, data processing and display unit, exhaust gas treatment unit. And the test bench was validated. The experimental results show that the test bench has the advantages of high-repeatability, high reliability and low cost. And it can realize automatic detection of multiple target values, which is worthy further promotion. Thereby, the article can contribute to the development of its technology indirectly.
基金Science and Technology Planning Project of Inner Mongolia Science and Technology Department(2022YFSH0021)Key Research and Development Program of Shaanxi Province(2024SF2-GJHX-14,2021SF-296)。
文摘Four types of Mg-5Zn porous scaffolds with different pore geometries,including body-centered cubic(bcc),the rhombic dodecahedron(RD),gyroid(G),and primitive(P)types,were designed and fabricated using selective laser melting.Their forming quality,compression mechanical properties,and degradation behavior were investigated.Results indicate that the fabricated scaffolds exhibit good dimensional accuracy,and the surface chemical polishing treatment significantly improves the forming quality and reduces porosity error in porous scaffolds.Compared to the ones with rod structures(bcc,RD),the scaffolds with surface structures(G,P)have less powder particle adhesion.The G porous scaffold exhibits the best forming quality for the same design porosity.The predominant failure mode of scaffolds during compression is a 45°shear fracture.At a porosity of 75%,the compression property of all scaffolds meets the compressive property requirements of cancellous bone,while bcc and G structures show relatively better compression property.After immersion in Hank's solution for 168 h,the B-2-75% pore structure scaffold exhibits severe localized corrosion,with fractures in partial pillar connections.In contrast,the G-3-75% pore structure scaffold mainly undergoes uniform corrosion,maintaining structural integrity,and its corrosion rate and loss of compressive properties are less than those of the B-2-75%structure.After comparison,the G-pore structure scaffold is preferred.
文摘Background: The study’s primary research suggests the relationship between high-school international students in China’s sleep quality and learning efficiency which is academic performance. Considering the effect of Chinese traditional cultural background, this study mainly investigates Chinese international high school students’ sleeping quality and patterns through the Pittsburgh Sleep Quality Index. Methods: A sample of 249 Chinese high school students in the Pearl River Region completed the questionnaire about their sleep quality using PSQI, their academic performance, and socio-demographic factors one month before the final exam in July 2023. Results: None of the students have good sleep quality, according to the PSQI;40.8% of students have poor sleep quality, and 59.2% have significant sleep disturbance. The results of ordinal logistic regression show that good sleep quality is positively associated with good academic performance. Conclusion: Our findings highlight the association between sleep and academic performance on the unique sleep patterns of Chinese international high school students, who often follow very different sleep patterns from other conventional students enrolled in the regular curriculum. High school students suffer from severe sleep deprivation and poor sleep quality. Under great academic stress, Chinese high school students should know the importance of sleep, balance sleep, and study.
文摘This study investigated the differences between children with and without learning difficulties(LD)regarding academic performance(AP)and sleep quality(SLQ).A total of 1,501 children were evaluated,including 810 with LD and 691 without LD.The results indicated that children with LD scored significantly lower in AP and had poorer sleep quality,with greater variability in SLQ patterns.Correlation analysis revealed a significant negative association between sleep quality and academic performance(r=-0.646;p<0.01),indicating that poorer sleep quality is related to lower academic performance.These findings underscore the importance of interventions focused on promoting sleep hygiene and consistent routines to mitigate the negative impacts of learning difficulties.Study limitations include the absence of mediating variables,such as screen time and mental health,suggesting the need for future research exploring longitudinal interventions and associated factors.
基金Project supported by the Technology and Achievement Transformation Project of Hangzhou,China(No.20161631E01)the Zhejiang University New Rural Development Research Institute Agricultural Technology Promotion Fund(No.2017006)+1 种基金the Zhejiang Provincial Natural Science Foundation of China(No.LY18C200006)the Basic Research Project of Education Department of Zhejiang Province(No.Y201737161),China
文摘Glycerol mono laurate(GML)has been widely used as an effective antibacterial emulsifier in the food in?dustry.A total of 360 44-week-old Hy-Line brown laying hens were randomly distributed into four groups each with six replicates of 15 birds,and fed with com-soybean-meal-based diets supplemented with 0,0.15,0.30,and 0.45 g/kg GML,respectively.Our results showed that 0.15,0.30,and 0.45 g/kg GML treatments significantly decreased feed conversion ratios(FCRs)by 2.65%,7.08%,and 3.54%,respectively,and significantly increased the laying rates and average egg weights.For egg quality,GML drastically in creased albume n height and Haugh units,and enhanced yolk color.Notably,GML increased the concentrations of polyunsaturated and monounsaturated fatty acids and reduced the concentration of total saturated fatty acids in the yolk.The albumen composition was also significantly modified,with an increase of 1.02%in total protein content,and increased 8ntents of His(4.55%)and Glu(2.02%)under the 0.30 g/kg GML treatment.Additionally,GML treatments had positive effects on the lipid metabolism of laying hens,including lowering the serum triglyceride and total cholesterol levels and reducing fat deposit!on in abdominal adipose tissue.Intestinal morphology was also improved by GML treatment,with increased villus length and villus height to crypt depth ratio.Our data demonstrated that GML supplementation of laying hens could have beneficial effects on both their productivity and physiological properties,which indicates the potential application of GML as a functional feed additive and gives us a new in sight into this traditional food additive.
文摘[Objective]The paper was to study the effects of xylooligosaccharide(XOS)and probiotics(PRO)and their interaction on the production performance,egg quality and intestinal short-chain fatty acids of laying hens in late laying period.[Method]A total of 36074-week-old Romain brown laying hens were randomly divided into four groups,six replicates each group and 15 chickens each replicate.The trial lasted 63 d.The laying hens in control group(CON)were fed with basal diet,and those in experimental groups were fed with the basal diets adding with 150 mg/kg XOS(XOS group),100 mg/kg probiotics(PRO group),150 mg/kg XOS+100 mg/kg probiotics(XOS-PRO group).[Result]Compared with the control group,the laying rate,daily egg production,yolk ratio,colonic acetic acid and caecal propionic acid in XOS group increased significantly(P<0.05),and the feed gain ratio decreased remarkably(P<0.05).PRO had no significant effect on the production performance and egg quality of laying hens in late laying period(P>0.05),but significantly increased colonic acetic acid(P<0.05).XOS and PRO had no interaction effect on the production performance,egg quality and intestinal short-chain fatty acids of laying hens in late laying period(P<0.05).[Conclusion]Adding XOS to the diet of laying hens in late laying period could increase the content of short-chain fatty acids in the hindgut of laying hens,and effectively improve the production performance and egg quality of laying hens in late laying period.Adding PRO to the diet did not significantly improve the production performance and egg quality of laying hens,and there was no interaction effect between XOS and PRO.
文摘To determine whether dried fermented ginger (DFG), fermented with Japanese mugwort silage juice, could be replaced by fermented corncob powder (FCP) as a of feed ingredient source without significant body weight decrease or damage to visceral organs (using gross anatomical observation), to intestinal villi (using light microscopy), or to the epithelial cells on the villus apical surface (using scanning electron microscopy) the following investigation was performed. Sixty-four male broilers were allotted to 4 groups: a basal diet group (control group), and basal diet groups with DFG at a level of 50 ppm;with DFG at 50 ppm and FCP at 250 ppm (50 ppm DFG + 250 ppm FCP group);and with FCP at a level of 500 ppm (500 ppm FCP group). Feed intake, body weight gain, feed efficiency, carcass quality, small intestinal length and weight, and visceral organ weight were not different among groups. Furthermore, regarding intestinal villus height, villus area and crypt depth, a significant difference was not found among the groups. When these values of the control were expressed as an index of 100, the duodenal villus height of the 50 ppm DFG + 250 ppm FCP group and the 500 ppm FCP group were 114 and 119, respectively. The duodenal villus area of the 50 ppm DFG + 250 ppm FCP group and the 500 ppm FCP group were 125 and 158, respectively. These villus heights and areas are thought to be activated. On the epithelial cells on the villus apical surface in the duodenum and jejunum, the 50 ppm DFG + 250 ppm FCP group had protuberated cells into the intestinal lumen and deeper cells at the sites of recently exfoliated cells, suggesting that these cells are activated. The present results indicate that small amounts of fermented corncob powder can be used as a feed supplement when mixed with fermented ginger powder, due to the synergy between the two ingredients, resulting in a 6% increase in body weight gain。
基金Supported by Harbin Applied Technology Research and Development Project(2016RAXXJ015)。
文摘This study aimed to investigate the effects of fermented puffed feather meal(FPFM)on growth performance,serum biochemical indices,meat quality,and intestinal microbiota in Arbor Acres(AA)broilers.A single-factor design was adopted,and four treatments were administered with five replicates to 240 one-day-old AA broilers.The control group(group A)received a basal diet,while the experimental groups received a basal diet plus 33%(group B),67%(group C)and 100%(group D)FPFM,respectively.Compared with group A,(1)the average daily gain(ADG)in group C decreased(P<0.05),and the feed conversion ratio(FCR)in group D increased(P<0.05);(2)the level of serum urea nitrogen in treatment groups decreased(P<0.05),and the levels of triglyceride,high density lipoprotein,low density lipoprotein,cholesterol,and glucose contents in group D increased(P<0.05)at day 21;(3)the serum immunoglobulin M and immunoglobulin G in group B and the immunoglobulin A in group C increased(P<0.05)at day 21,and the serum immunoglobulin M and immunoglobulin G in group D decreased(P<0.05)at day 42;(4)the share force of breast muscle and thigh muscle in group D increased(P<0.05);(5)the villus height to crypt depth ratio in the jejunum of group B increased(P<0.05)at day 21,and the villus height in group C and D increased(P<0.05)at day 42;(6)the proteobacteria counts in the cecum digesta in treatment groups decreased(P<0.05)at day 21.The basal diet supplemented with 33%FPFM promoted protein metabolism,enhanced immunity and improved meat quality,promoted the digestion and absorption of nutrients,increased intestinal microbial diversity,and improved the content of beneficial bacteria without affecting the growth performance,it was possible to be used as a good substitute for fish meal.
基金The National Natural Science Foundation of China(No. 50976022)
文摘A heat transfer performance testing system is presented with its hardware structure, operation principle, and software control and measurement system. Working fluids of the subsystem include thermal conducting oil, compressed air, glycol water solution and water as the heating fluids, and air and water as the cooling fluids. The heat transfer performance testing of heat exchangers can be conducted not only for a conventional one heating fluid to one cooling fluid, but also for a compound air cooling heat exchanger with two or three heating fluids in parallel or in series. The control and measurement system is implemented based on a LabVIEW software platform, consisting of the data acquisition and process system, and the automotive operation and control system. By using advanced measuring instruments combined with sound computer software control, the testing system has characteristics of a compact structure, high accuracy, a wide range of testing scope and a friendly operation interface. The uncertainty of the total heat transfer coefficient K is less than 5%. The testing system provides a reliable performance testing platform for designing and developing new heat exchangers.
基金Supported by Key Program of Provincial Science&Technology Department(2014N3011)Special Program of Provincial Science&Technology Department Key Program(2014NZ0002)Longyan S&T Program(2015LY32)~~
文摘In this paper, Duroc-lanndrae-Yorkshire crossbred piggy of born at 75 days of age, bouncing with health and similar body weight were randomly divided into experimental group （136 pigs） and control group （136 pigs）. Pigs in control group were fed with conventional diets, and 4% microbial fermentation feeds were added to the basal diet of experimental group to research on the effect of performance and meat quality of pig breeding. The results indicated that after feeding 106 d, compared to control group, the slaughter performance, meat quality and content of fatty acid and amino acid of experimental group were all better, its slaughter rate increased 1.53%, the carcass weight increased 2.75% and the backfat thickness decreased 0.02 cm. In addition, the pork meat in test group hadn＇t antibiotic and heavy metal residues, while it had higher color score, lower pH45min and pH24h value, better tenderness and rate of cooked meat and higher content of fatty acids, polyunsaturated fatty acids and amino acids. Microbial fermentation feed using in test group can significantly improved the flavor and aroma of pork, and eating this pork conducive more to human health. Thus, the application of microbial fermenta- tion feed can provide a more safe, healthy and nutritious flavor pork for human beings.
文摘To realize automatic control of automobile transmission performance test stand Methods The automatic control technique of the lubricant temperature,the program- controll- edautomaticshifting of the transmission,the continuous adjusting of revolution speed and load, data-acquisition and data real-time processing were adopted.Results The lubricant temperature was controlled at the set temperature ±2℃.The automatic shifting of the trans- mission is simple,reliable and accurate.The automatic adjusting of load and rotation speed is rapidandaccurate,the torque divergence is ±1N·m,the rotation speed divergence is ±5r/min Conclusion The four kinds of techniques are applied into the automobile transmission perfor- mance test stand successfully. mancetest stand successfully.
基金Supported by Key Technologies Research and Development Program of Zhanjiang[(2012)196]~~
文摘[Objective]This study aimed to evaluate the meat quality of frizzle Chick-en, and to find out the correlation between the meat quality and slaughter perfor-mance. [Method] The slaughter performance such as live chicken weight, carcass weight, semi-eviscerated weight, eviscerated weight, chest muscle weight, leg mus-cle weight, abdominal fat weight and the meat quality indices like color, pH and shear force of 12-week-old frizzle chickens were measured to analyze the correla-tion between slaughter performance and meat quality. [Result] The carcass percent-age, semi-eviscerated percentage, eviscerated percentage, chest muscle percentage, leg muscle percentage, abdominal fat percentage, intramuscular fat width and subcu-taneous fat thickness of the male chickens were 89.76%, 81.54%, 67.53%, 7.82%, 11.29%, 2.42%, 0.69 cm and 0.48 cm, of female chickens were 89.78%, 80.87%, 62.94%, 6.19%, 9.92%, 3.91%, 0.78 cm and 0.61 cm. Some of these traits exhibit-ed significant difference between the male and female chickens （P〈0.05）. In male chickens, the chest muscle color, pH and shear force were 5.93, 6.15 and 3.72 kg, and the leg muscle color, pH and shear force were 6.18, 6.54 and 3.41 kg; in fe-male chickens, the chest muscle color, pH and shear force were 5.77, 6.05 and 3.41 kg, and the leg muscle color, pH and shear force were 6.03, 6.21 and 2.74 kg. The quality of chest and leg muscles of frizzle chickens significantly differed （P〈0.05）. Carcass weight had significant positive correlations with semi-eviscerated weight and meat color （P〈0.05）, and an extremely significant positive correlation with pH （P〈0.01）. Semi-eviscerated weight and pH value shared a significant posi-tive correlation （P〈0.05）. Eviscerated weight and leg muscle weight shared an ex-tremely significant negative correlation （P〈0.01）. Abdominal fat weight correlated sig-nificantly and negatively with shear force （P〈0.05）. Meat color and pH value had a significant positive correlation （P〈0.05）. [Conclusion] This study provides theoretical basis for the breeding of excellent chicken varieties producing high-quality meat.
文摘This study aimed to study the germplasm characteristics of Tibetan goat distributed in Sichuan. Three male and three female goats of twelve-month-old Ti-betan goat were selected, and they were slaughtered for analysis of slaughter per-formance, muscle quality and muscle nutrients. The results showed that the pre-slaughter body weights, dressing percentages, meat percentages and carcass meat production rates of male and female Tibetan goats were （14.33±1.53） and （12.50±2.18） kg, （42.11±5.26）% and （43.85±4.51）%, （31.34±3.36）% and （32.84±3.16）%, and （72.34±0.54）% and （72.30±0.78）%, respectively. There were smal differences in car-cass size, carcass segmentation, muscle fiber properties, muscle quality, muscle nu-tritional composition, muscle minerals contents and muscle heavy metals contents between male and female Tibetan goats. A total of 18 kinds of amino acids were detected in the muscle of male and female Tibetan goats. The EAA/TAA ratios and EAA/NEAA ratios of male and female Tibetan goats were （39.18＆#177;0.38）%and （38.70±0.72）%, and （64.31±1.03）% and （63.21±1.92）%, respectively.
基金Supported by Special Fund for Animal Husbandry Science and Technology in Sichuan Province~~
文摘[Objective] This study was conducted to understand goat germplasm char- acteristics. [Method] With some 24-month-old males and females Tibet goats as experimental materials, a slaughter experiment was carried out to determine their slaughter performance, muscle quality and muscle nutritional components. [Result] The body weights of males and females before slaughter were （20.16±1.26） and （19.33±4.86） kg, respectively; the dressing percentages of males and females were （43.86±1.74）% and （44.08±5.46）%, respectively; the meat percentages were （32.43± 1.52）% and （32.72±3.97）%, respectively; and the meat production rates of carcass were （73.28±0.09）% and （73.16±0.85）%, respectively. There were less differences in carcass measurements, carcass segmentation, muscle quality, muscle fiber charac- teristics, muscle nutritional components, muscle mineral contents and heavy metal contents between males and females, while eye muscle area and hind leg meat weight of males were significantly higher than those of females. In muscles of males and females, 18 amino acids were detected totally, EAA/TAA values were （39.23±0.24）% and （38.70±0.15）%, respectively, and EAA/NEAA values were （64.73± 0.65）% and （63.17±0.41）%, respectively. [Conclusion] This study lays a foundation for overall understanding of germplasm characteristics of Tibetan goats.
文摘[Objective] The aim was to discuss the resource characteristics of Danba goat. [Method] Three male and three female goats of twelve-month-old Danba goat were selected to slaughter,and their slaughter performance, muscle qulity and mus- cle nutrients were determined. [Result] The pre-slaughter weights, dressing percent- ages, meat percentages and carcass meat production rates of the male and female Danba goats were （25.83±1.04） and （18.50±2.29） kg, （45.18±0.78）% and （38.89± 2.08）%, （33.76±1.4）% and （28.59±1.99）%, and （74.30±0.85）% and （74.08±0.65）%, respectively. The carcass length, carcass hind leg circumstance, carcass hind leg length, lumbar muscle thickness, hind leg meat yield, shoulder muscle yield and breast meat yield of male goats were significantly higher than those of female goats （P〈0.05）, and no significant differenceswere found in other carcass size and carcass segmentation indices between male and female goats （P〉0.05）. There were small differences in muscle fiber properties, muscle quality, muscle nutritional composition, muscle mineral content and muscle heavy metal content between male and female goats （P〈0.05）. A total of 18 kinds of amino acids were detected in the male and female goats. The EAA/TAAs and EANNEAAs of male and female goats were （39.56±0.26）% and （39.48±0.66）%, and （65.45±0.71）% and （65.43±1.80）%, respec- tively. [Conclusion] This study will provide the basis for the understanding of the resource characteristics of Danba goat.
基金supported by the National Basic Research Program of China(No.2012CB124704 and 2013CB127305)KC.Wong Education Foundation,Hong Kong
文摘Background： The protein/energy ratio is important for the production performance and utilization of available feed resources by animals. Increased protein consumption by mammals leads to elevated feed costs and increased nitrogen release into the environment. This study aimed to evaluate the effects of dietary protein/energy ratio on the growth performance, carcass traits, meat quality, and plasma metabolites of pigs of different genotypes. Methods： Bama mini-pigs and Landrace pigs were randomly assigned to two dietary treatment groups （Chinese conventional diet with low protein/energy ratio or National Research Council diet with high protein/energy ratio; n = 24 per treatment） in a 2 x 2 factorial arrangement. Blood and muscle samples were collected at the end of the nursery, growing, and finishing phases. Results： We observed significant interactions （P 〈 0.05） between breed and diet for total fat percentage, intramuscular fat （IMF） content, protein content in biceps femoris （BF） muscle, and plasma urea nitrogen （UN） concentration in the nursery phase; for average daily gain （ADG）, average daily feed intake （ADFI）, dry matter, IMF content in psoas major （PM） muscle, and plasma total protein and albumin concentrations in the growing phase; and for drip loss and plasma UN concentration in the finishing phase. Breed influenced （P 〈 0.05） growth performance, carcass traits, and meat quality, but not plasma metabolites. Throughout the trial, Landrace pigs showed significantly higher （P 〈 0.0_5） ADG, ADFI, dressing percentage, lean mass rate, and loin-eye area than did Bama mini-pigs, but significantly lower （P 〈 0.0.5） feed/gain ratio, fat percentage, backfat thickness, and IMF content. Dietary protein/energy ratio influenced the pH value, chemical composition of BF and PM muscles, and plasma activities of glutamic-pyruvic transaminase and gamma-glutamyl transpeptidase, and plasma concentration of UN. Conclusions： Compared with Landrace pigs, Bama mini-pigs showed slower growth and lower carcass performance, but had better meat quality. Moreover, unlike Landrace pigs, the dietary protein/energy ratio did not affect the growth performance of Bama mini-pigs. These results suggest that, in swine production, low dietary protein/energy ratio may be useful for reducing feed costs and minimizing the adverse effects of ammonia release into the environment.
基金supported by the National Key Research and Development Program of China(Nos.2016YFF0103004 and 2017YFC0209504)the National Natural Science Foundation of China(No.91544218)+1 种基金the Science and Technological Fund of Anhui Province for Outstanding Youth(No.1808085J19)the Special Research of Public Welfare Industry of Environmental Protection(201409011)
文摘PM2.5 separator directly affects the accuracy of PM2.5 sampling.The specification testing and evaluation for PM2.5 separator is particularly important,especially under China’s wide variation of terrain and climate.In this study,first a static test apparatus based on polydisperse aerosol was established and calibrated to evaluate the performance of the PM2.5 separators.A uniform mixing chamber was developed to make particles mix completely.The aerosol concentration relative standard deviations of three test points at the same horizontal chamber position were less than 0.57%,and the particle size distribution obeyed logarithmic normal distribution with an R2 of 0.996.The flow rate deviation between the measurement and the set point flow rate agreed to within±1.0%in the range of-40 to 50℃.Secondly,the separation,flow and loading characteristics of three cyclone separators(VSCC-A,SCC-A and SCC112)were evaluated using this system.The results showed that the 50%cutoff sizes(D50)of the three cyclones were 2.48,2.47 and 2.44μm when worked at the manufacturer’s recommended flow rates,respectively.The geometric standard deviation(GSD)of the capture efficiency of VSCCA was 1.23,showed a slightly sharper than SCC-A(GSD=1.27),while the SCC112 did not meet the relevant indicator(GSD=1.2±0.1)with a GSD=1.44.The flow rate and loading test had a great effect on D50,while the GSD remained almost the same as before.In addition,the maintenance frequency under different air pollution conditions of the cyclones was summarized according to the loading test.
基金supported by the National Natural Science Foundation of P.R.China (No.NSFC30525029)
文摘Two experiments were conducted to in- vestigate the effects of net energy （NE） level on the performance and carcass traits of finishing pigs fed low crude protein （CP） diets supplemented with crystalline amino acids （CAA）. A total of 216 （Exp. 1） and 360 （Exp. 2 ） barrows （ Yorkshire × Landrace× Duroc ） were allotted to one of six treatments （n =6）. The experimental diets were based on corn and soybean meal, and consisted of a high-CP diet that contained approximately 16% CP and 2.50 Mcal/kg of NE as well as five low-CP diets in which the CP level of the diet was reduced by approximately four percentage units but was supplemented with crystalline lysine, methionine, threonine, and tryptophan. The low CP diets provided 2.64, 2.58, 2.50, 2.42, or 2.36 Mcal/kg in Exp. 1 as well as 2.45, 2.40, 2.35, 2.30, or 2.25 Mcai/kg in Exp.2. In Exp. 1, a linear （P=0.03） increase in weight gain was observed with decreasing NE level while the ratio of gain to feed was unaffect- ed （P 〉 0.05） by NE level. There was a linear in-crease （P = 0.01 ） in the percentage of fat-free lean and a linear decrease （ P = 0.03 ） in the percentage of total fat with decreasing NE levels. In Exp. 2, a sig- nificant quadratic （ P = 0.03 ） effect of NE level was observed for weight gain. The ratio of gain to feed demonstrated a significant （P 〈0.01 ） quadratic effect with pigs fed 2.35 and 2.40 Mcal/kg of NE, Pigs fed the diet containing 2.40 Mcal/kg of NE had the lowest percentage of total fat （36. 95% ） and the highest percentage of fat-free lean （49.36%）. The overall results of these experiments indicate that feed- ing either a surplus or a deficiency of NE is detrimen- tal to both pig performance and carcass composition when low CP diets supplemented with CAA are fed. Our results indicate that when the CP content of the diet is reduced by four percentage units and the diet is properly supplemented with CAA, maximum per- formance and carcass quality will be obtained if the diet provides approximately 2.42 Mcal/kg of NE.
基金supported by the System for Poultry Production Technology,Beijing Innovation Research Team of Modern Agriculture(CARSPSTP)the National Key Technology R&D Program of China during the 12~(th) five-year plan(2012BAD39B04)
文摘Background： Highly automated cage-rearing systems are becoming increasingly popular in China. However, a high stocking density can cause oxidative stress and decrease broiler performance. The tryptophan （TRP） derivative 5-hydroxytryptophan （5-HT） has been shown to preserve membrane fluidity in birds suffering from oxidative stress Therefore, this experiment was conducted to determine the effects of dietan/TRP supplementation on performance, breast meat quality and oxidative stress in broilers reared in cages with a high or low stocking density. Methods： Female Arbor Acres broilers （25-d-old, n = 144） were randomly allocated to 1 of 4 treatments. The birds were fed a diet based on corn, soybean meal, cottonseed meal and corn gluten meal containing either 0.18 or 0.27% TRP and were housed with stocking densities of 11 or 15.4 birds/m2 in a 2 x 2 factorial experiment. Broiler performance was evaluated from d 25 to 42. Eight birds from each treatment were slaughtered on d 42 and plasma and breast muscle samples were collected to measure biochemical indices. Results： A higher stocking density tended to be associated with reduced weight gain （P 〈 0.10）, and significantly increased plasma glutamic-pyruvic transaminase （GPT） activity （P 〈 0.001）. Increased dietary TRP significantly reduced the activities of lactic dehydrogenase and GPT while increasing total cholesterol in the plasma （P 〈 0.01）, reducing drip loss of breast muscle （P 〈 0.10） and improving feed efficiency （P 〈 0.10）. Conclusions： An increase in dietary TRP, ].S-fold higher than the standard supplementation level, can alleviate oxidative stress as well as improve welfare and feed efficiency in broilers reared in cages with a high stocking density.
