Oils with different degree of saturation:effects on ileal digestibility of fat and corresponding additivity and bacterial community in growing pigs

Background Oils are important sources of energy in pig diets.The combination of oils with different degree of saturation contributes to improve the utilization efficiency of the mixed oils and may reduce the cost of oil supplemented.An experiment was conducted to evaluate the effects of oils with different degree of saturation on the fat digestibility and corresponding additivity and bacterial community in growing pigs.Methods Eighteen crossbred(Duroc×Landrace×Yorkshire)barrows(initial body weight:29.3±2.8 kg)were surgically fitted with a T-cannula in the distal ileum.The experimental diets included a fat-free basal diet and 5 oil-added diets.The 5 oil-added diets were formulated by adding 6%oil with different ratio of unsaturated to saturated fatty acids(U:S)to the basal diet.The 5 oils were palm oil(U:S=1.2),canola oil(U:S=12.0),and palm oil and canola oil were mixed in different proportions to prepare a combination of U:S of 2.5,3.5 and 4.5,respectively.Results The apparent and standardized ileal digestibility(AID and SID)of fat and fatty acids increased linearly(P<0.05)as the U:S of dietary oils increased except for SID of fat and C18:2.The AID and SID of fat and fatty acids differed among the dietary treatments(P<0.05)except for SID of unsaturated fatty acids(UFA)and C18:2.Fitted one-slope broken-line analyses for the SID of fat,saturated fatty acids(SFA)and UFA indicated that the breakpoint for U:S of oil was 4.14(R^(2)=0.89,P<0.01),2.91(R^(2)=0.98,P<0.01)and 3.84(R^(2)=0.85,P<0.01),respectively.The determined SID of fat,C18:1,C18:2 and UFA in the mixtures was not different from the calculated SID of fat,C18:1,C18:2 and UFA.However,the determined SID of C16:0,C18:0 and SFA in the mixtures were greater than the calculated SID values(P<0.05).The abundance of Romboutsia and Turicibacter in pigs fed diet containing palm oil was greater than that in rapeseed oil treatment group,and the two bacteria were negatively correlated with SID of C16:0,C18:0 and SFA(P<0.05).Conclusions The optimal U:S for improving the utilization efficiency of mixed oil was 4.14.The SID of fat and UFA for palm oil and canola oil were additive in growing pigs,whereas the SID of SFA in the mixture of two oils was greater than the sum of the values of pure oils.Differences in fat digestibility caused by oils differing in degree of saturation has a significant impact on bacterial community in the foregut.

Effects of dietary amylose to amylopectin ratio on growth performance,carcass quality characteristics and meat fatty acids in Chinese Qinchuan cattle

This study evaluated the effects of the dietary starch amylose/amylopectin ratio on growth performance,rumen fermentation and blood parameters,carcass characteristics and marbling score,and meat fatty acid profiles and transcriptional changes in the genes involved in the gluconeogenesis pathway in Chinese Qinchuan cattle.Forty-five cattle were randomly divided into three groups.The bulls were fed a control diet(middle amylose/amylopectin ratio=0.47)or diets with either waxy corn starch(WS)inclusion(low amylose/amylopectin ratio=0.23)or pea starch(PS)inclusion(high amylose/amylopectin ratio=0.60)for 90 days.The bulls were individually allowed to receive the diets at the daily amount of at least 2.1%of their individual BW twice daily.The bulls were weighed at 45-day intervals,and blood and rumen fluid samples were also collected at 45-day intervals.The bulls were slaughtered and longissimus thoracis(LT)samples were collected for meat quality measurements.Compared with PS,the average daily gain(ADG)and feed efficiency in control and WS were increased(P<0.05)during d 0 to 45.However,the feed efficiency in PS was increased(P<0.05)compared with the control and WS during d 46 to 90.During the whole feeding trial,the ADG in control and WS showed trends that were higher(0.05<P<0.1)than that of PS,while other growth performance measures and feed intake did not differ(P>0.05)among the three groups.Compared with PS,the serum insulin concentration in WS was increased(P<0.05)at d 45,but not at d 90.Compared with control and WS,the serum SOD and T-AOC concentrations in PS were increased(P<0.05)at d 45,but not at d 90.Compared with control,the rumen microbial crude protein contents in WS and PS were increased(P<0.05)at d 0,while those of control and WS were higher(P<0.05)than that of PS at d 45,but not at d 90.Compared with PS,the backfat thickness in control and WS were increased(P<0.05),however,the marbling score and expression of genes related to the gluconeogenesis pathway in liver of the three groups did not differ(P>0.05).Chemical and physio-chemical compositions of LT did not differ(P>0.05)among the three groups.In conclusion,diets with low or middle amylose/amylopectin ratios increased the backfat thickness,and tended to improve ADG,but had no effect on other carcass characteristics,fat content in the LT,or the expression of hepatic genes related to the gluconeogenesis pathway in Chinese Qinchuan cattle.

Shifting perspectives-interplay between non-alcoholic fatty liver disease and insulin resistance in lean individuals

Non-alcoholic fatty liver disease(NAFLD)has become a significant public health burden affecting not only obese individuals but also people with normal weight.As opposed to previous beliefs,this particular subset of patients has an increased risk of all-cause mortality and worse outcomes than their obese counterparts.The development of NAFLD in lean subjects seems to be interconnected with metabolic phenotype,precisely visceral fat tissue,sarcopenia,and insulin resistance.Here,we summarize available data focusing on the co-dependent relationship between metabolic phenotype,insulin resistance,and development of NAFLD in lean individuals,suggesting more appropriate tools for measuring body fat distribution for the screening of patients at risk.

Fat-to-muscle Ratio: A New Anthropometric Indicator for Predicting Metabolic Syndrome in the Han and Bouyei Populations from Guizhou Province, China

Objective To investigate the prevalence and possible factors influencing metabolic syndrome in people from Guizhou Province and to explore the predictive value of the fat-to-muscle ratio in diagnosing metabolic syndrome. Methods A multistage stratified sampling method was used in this cross-sectional study of 20-80 years old Han and Bouyei populations from Guizhou Province, southwestern China, from October-December 2012. The study included 4,553 cases of metabolic syndrome, that was defined according to 2005 International Diabetes Federation criteria. The receiver operating characteristic curve was used for determining the sensitivity, specificity, and predictive ability of the fat-to-muscle ratio for the diagnosis of metabolic syndrome. Results The age-standardized prevalence of metabolic syndrome was 11.38%（men： 9.76%; women： 12.72%） for Han and 4.78%（men： 4.43%; women： 5.30%） for Bouyei populations. In Guizhou Province, the cut-off value for the men fat-to-muscle ratio was 0.34, the area under the curve was 0.95, and the sensitivity and specificity were 0.94 and 0.85, respectively. The cut-off value for the women fat-to-muscle ratio was 0.55, the area under the curve was 0.91, and the sensitivity and specificity were 0.93 and 0.79, respectively. Conclusion The fat-to-muscle ratio is highly predictive of metabolic syndrome in Guizhou Province, and a useful reference indicator.

Time-Lag Effect of Dietary Fiber and Fat Intake Ratio on Japanese Colon Cancer Mortality

The daily intake of total dietary fiber (TDF) was evaluated from data of the National Nutrition Survey (NNS) in Japan for 41 years since 1947. An interrelationship between the nutrient intake, including TDF, and the mortality from colon cancer in Japanese people was calculated by a simple correlation coefficient and time-series correlation coeffcient.TDF intake per capita decreased rapidly from 27.4 g in 1947 to 15.8 g in 1963, and subsequently decreased by a lesser rate to 15.3 g in 1987. Fat intake increased rapidly from 18.0 g in 1950 to 56.6 g in 1987.The age-adjusted mortality from colon cancer shows a significant positive correlation with both the intakes of animal protein and of total fat, and the fat energy ratio. A time-series analysis indicates that the mortality from colon cancer was negatively correlated with TDF with a 15-27 year delay, the maximum correlation existing with a 23-year lag (r = -0.947). The TDF intake was less than 17.9 g in 1965. At the same time, the mortality from colon cancer increased rapidly. A fat/TDF ratio above 3.0 resulted in a rapid increase in colon cancer mortality.The non-adjusted mortality from colon cancer has much the same interrelationship with TDF and fat intake as the adjusted figures. It is suggested that the cause of the increased mortality from colon cancer in Japan is positively related to the increased intake of fat and protein. In addition, the decrease in TDF intake has accelerated the mortality of colon cancer after a delay of 23-24 years. The importance of fat/TDF as a nutritional criterion for the incidence of colon cancer needs to be better recognized

The Influence of Forage/Concentrate Ratio and Full Fat Soya By-Pass Supplementation on the Fatty Acids Profile from the Carcase of Fatting Lambs

There was organized a 2×2 factorial type experience in which it has been aimed the influence of forage/concentrates ratio and the effect of supplementing the ratio with full fat soya by-pass （FFS） on the production performance and carcass fatty acid profile of fattening lambs. 32 Tsigai lambs were divided into 4 groups and were fed with 2 different diets regarding the forage/concentrates ratio （35/65 and 65/35, on a DM basis）, containing or not 5% FFS （full fat soya treated with formaldehyde 12.5%）. Including FFS in diet and the ratios rich in concentrates determined a significant improvement in weight gain （P〈0.01）, in the degree of food recovery and in fatty acid profile from the carcass. It has been significantly increased （P〈0.01） the weight of polyunsaturated fatty acids （PUFA） from intramuscular fat （longissimus dorsi-LD and femoral biceps-FB） and the deposit fat （subcutaneous-SC and perirenal-PR） and decreased the proportion of saturated （SFA） and monounsaturated fatty acids （MUFA）. Most significant differences were recorded about PUFA from Omega-3 series （C18：3 n-3, EPA C22：3 n-3, DPA and DHA） and CLA isomers （conjugated linolenic acid： C 18：2 C9, tl I＋C 18：2 t10, C 12）. The best profile of fatty acids, considered in light of the influence on human health （high concentration of Omega 3 fatty acids and CLA and low in SFA） was established in LD, for lambs fed with diets high in concentrates and which contained FFS （HC/S）.

Colorectal neoplasm:Magnetic resonance colonography with fat enema-initial clinical experience

AIM： To assess Magnetic resonance colonography with fat enema as a method for detection of colorectal neoplasm.METHODS： Consecutive twenty-two patients underwent MR colonography with fat enema before colonoscopy. Tl-weighted three-dimensional fast spoiled gradient- echo with inversion recovery sequence was acquired with the patient in the supine position before and 75 s after Gadopentetate Dimelumine administration. Where by, pre and post MR coronal images were obtained with a single breath hold for about 20 s to cover the entire colon. The quality of MR colonographs and patients＇ tolerance to fat contrast medium was investigated. Colorectal neoplasms identified by MR colonography were compared with those identified on colonoscopy and sensitivity of detecting the lesions was calculated accordingly.RESULTS： MR colonography with fat enema was well tolerated without sedation and analgesia. 120 out of 132 （90.9%） colonic segments were well distended and only 1 （0.8%） colonic segment was poor distension. After contrast enhancement scan, mean contrast-to-noise ratio （CNR） value between the normal colonic wall and lumen was 18.5 ± 2.9 while mean CNR value between colorectal neoplasm and lumen was 20.2± 3.1. By Magnetic resonance colonography, 26 of 35 neoplasms （sensitivity 74.3%） were detected. However, sensitivity of MRC was 95.5% （21 of 22） for neoplasm larger than 10 mm and 55.6% （5 of 9） for 5-10 mm neoplasm.CONCLUSION： MR colonography with fat enema and Tl-weighted three-dimensional fast spoiled gradientecho with inversion recovery sequence is feasible in detecting colorectal neoplasm larger than 10 mm.

Relationship between high dietary fat intake and Parkinson’s disease risk: a meta-analysis

OBJECTIVE: To assess whether dietary fat intake influences Parkinson’s disease risk. DATA SOURCES: We systematically surveyed the Embase and PubMed databases, reviewing manuscripts published prior to October 2018. The following terms were used:(“Paralysis agitans” OR “Parkinson disease” OR “Parkinson” OR “Parkinson’s” OR “Parkinson’s disease”) AND (“fat” OR “dietary fat” OR “dietary fat intake”). DATA SELECTION: Included studies were those with both dietary fat intake and Parkinson’s disease risk as exposure factors. The Newcastle-Ottawa Scale was adapted to investigate the quality of included studies. Stata V12.0 software was used for statistical analysis. OUTCOME MEASURES: The primary outcomes included the relationship between high total energy intake, high total fat intake, and Parkinson’s disease risk. The secondary outcomes included the relationship between different kinds of fatty acids and Parkinson’s disease risk. RESULTS: Nine articles met the inclusion criteria and were incorporated into this meta-analysis. Four studies scored 7 and the other five studies scored 9 on the Newcastle-Ottawa Scale, meaning that all studies were of high quality. Meta-analysis results showed that high total energy intake was associated with an increased risk of Parkinson’s disease (P = 0.000, odds ratio (OR)= 1.49, 95% confidence interval (CI): 1.26–1.75);in contrast, high total fat intake was not associated with Parkinson’s disease risk (P = 0.123, OR = 1.07, 95% CI: 0.91–1.25). Subgroup analysis revealed that polyunsaturated fatty acid intake (P = 0.010, OR = 1.03, 95% CI: 0.88–1.20) reduced the risk of Parkinson’s disease, while arachidonic acid (P = 0.026, OR = 1.15, 95% CI: 0.97–1.37) and cholesterol (P = 0.002, OR = 1.09, 95% CI: 0.92–1.29) both increased the risk of Parkinson’s disease. Subgroup analysis also demonstrated that, although the results were not significant, consumption of n-3 polyunsaturated fatty acids (P = 0.071, OR = 0.88, 95% CI: 0.73–1.05),α-linolenic acid (P = 0.06, OR = 0.86, 95% CI: 0.72–1.02), and the n-3 to n-6 ratio (P = 0.458, OR = 0.89, 95% CI: 0.75–1.06) were all linked with a trend toward reduced Parkinson’s disease risk. Monounsaturated fatty acid (P = 0.450, OR = 1.06, 95% CI: 0.91–1.23), n-6 polyunsaturated fatty acids (P = 0.100, OR = 1.15, 95% CI: 0.96–1.36) and linoleic acid (P = 0.053, OR = 1.11, 95% CI: 0.94–1.32) intakes were associated with a non-significant trend toward higher PD risk. Saturated fatty acid (P = 0.619, OR = 1.01, 95% CI: 0.87–1.18) intake was not associated with Parkinson’s disease. CONCLUSION: Dietary fat intake affects Parkinson’s disease risk, although this depends on the fatty acid subtype. Higher intake of polyunsaturated fatty acids may reduce the risk of Parkinson’s disease, while higher cholesterol and arachidonic acid intakes may elevate Parkinson’s disease risk. However, further studies and evidence are needed to validate any link between dietary fat intake and Parkinson’s disease.

Three-Dimensional Models for Analyzing the Cyclic Variations in a Lean Burn CNG Engine

Three-dimensional models, consisting of the flame kernel formation model, flame kernel development model and natural gas single step reaction model, are used to analyze the contribution of cyclic equivalence ratio variations to cyclic variations in the compressed natural gas （CNG） lean burn spark ignition engine. Computational results including the contributions of equivalence ratio cyclic variations to each combustion stage and effects of engine speed to the extent of combustion variations are discussed. It is concluded that the equivalence ratio variations affect mostly the main stage of combustion and hardly influence initial kernel development stage.

Impact of Lifestyle Intervention on the Estimated Visceral Fat Area and Skeletal Muscle Mass in Men with Obesity

Background: The lifestyle modification remains the fundamental approach for the obesity treatment. The aim of this study is to demonstrate the effect of the multimodal lifestyle intervention on the estimated visceral fat area versus changes in musculoskeletal mass in a cohort of adult men with obesity. Subjects and Methods: A retrospective cohort study in which the file of eighty-two male subjects, aged 20 - 60 years, was studied for three months. Patients had been instructed to follow a balanced-hypocaloric diet, physical activity plan and general advice for combating the unhealthy lifestyle habits through the study period. Those who succeeded to loss > 5% of their body weight were classified as weight loser (WL) group, while others as weight resistant (WR) group. The results of In Body-720 bioelectric impedance analysis were used to report the fat mass (FM), visceral fat area (VFA), skeletal muscle mass (SMM), SMM/VFA ratio, osseous mass (OM), and basal metabolic rate (BMR) before and after the study period. Anthropometric measures, glucose, and lipid profile were also analyzed. Paired t-test was used to detect the significance of change between before and after measures, independent sample t-test was used to compare WL vs. WR groups. Results: There were significant decreases in weight, FM (p 0.05) and VFA (p 0.001), in addition to a significant rise of SMM/VFA ratio (p 0.05), together with insignificant changes of osseous mass, SMM and BMR after 3 months. Additionally, total cholesterol, low-density lipoprotein, and triglycerides were significantly reduced (P 0.05). The percentages of reduction in weight, FM and VFA in WL vs. WR groups were highly significant (p 0.001), while the percentages of change in SMM, SMM/VFA ratio and BMR were significant (p 0.05). Conclusion: Lifestyle modification might be effective in production of positive changes in the body composition of patients with obesity. These changes were more significant in weight losers.

Development and Production of Omega-3 Fatty Acids-Enriched Foods is an Important Dietary Strategy to Improve People's Nutritional and Health Status

Both Omega-6 and Omega-3 fatty acids are essential nutrients important for cellular structure and function but cannot be synthesized by the human body and must be obtained from food.These two classes of fatty acids are metabolically and functionally different and antagonistically regulate many physiological and pathological processes.Thus,the relative balance between Omega-6 and Omega-3 fatty acids are critical for good health.However,today’s diet contains too much Omega-6 but too little Omega-3,leading to a severe imbalance with a very high Omega-6/Omega-3 ratio(>10)in most people.Many lines of evidence suggest that this imbalance is a key factor contributing to the development of modern chronic diseases.A growing number of studies ranging from laboratory research to clinical trials have shown that balancing the tissue ratio of Omega-6/Omega-3 fatty acids by increasing tissue levels of Omega-3 fatty acids and/or decreasing the content of Omega-6 fatty acids are very beneficial for the prevention and treatment of many life-threating chronic diseases as well as for health promotion of the general public.Therefore,development and production of foods rich in Omega-3-fatty acids should be considered as a key health program to balance essential fat intake and thereby improve the nutritional and health status of all people.

超声B-Mode Ratio对糖尿病患者颌下腺脂肪沉积的诊断效能

为了对比评价超声B-mode ratio及MR-IP-OP两种检查方法对糖尿病患者颌下腺脂肪沉积的诊断效能。选取志愿者174人(糖尿病患者89人和健康志愿者85人),利用超声B-mode ratio技术和3D MR-IP-OP方法评估和检测颌下腺的脂肪含量。使用独立样本t检验比较两组患者B-radio和MRI-IP-OP的FF值组间差异。采用受试者工作特征曲线(ROC)分析两种技术对颌下腺脂肪沉积的诊断效能。用Spear-man相关系数评价两组参数之间的相关性。糖尿病组的B-mode ratio值(1.337±0.128)明显高于正常组(0.917±0.138)。糖尿病组MR-IP-OP的FF值(21.88±7.86%)明显高于正常组(8.87±3.09%)。ROC曲线表明脂肪沉积评价中B-mode ratio和3D MR-IP-OP的曲线下面积(AUC)分别为0.860和0.909,超声B-mode ratio和3D MR-IP-OP方法获得的结果间有良好相关性(r=0.502,p<0.001)。超声B-mode ratio对颌下腺脂肪变性的诊断具有良好的诊断效能,可以替代MR-IP-OP检查技术,并且有很好的临床应用前景。

健康体检人群内脏脂肪面积与尿酸/高密度脂蛋白胆固醇比值的相关性研究

目的探讨健康体检人群内脏脂肪面积(VFA)与尿酸(UA)/高密度脂蛋白胆固醇(HDL-C)比值(UHR)的相关性。方法随机选取2020年6月至2022年6月于枣庄市立医院进行健康体检的人群360名。根据VFA值,将人群分为内脏脂肪型肥胖组(VFA≥100 cm^(2))172名和对照组(VFA<100 cm^(2))188名,比较两组一般资料及生化指标。采用Spearman相关分析评估VFA与UHR的相关性,多元线性回归分析UHR的影响因素;采用受试者工作特征(ROC)曲线评估UHR对内脏脂肪型肥胖的预测价值。结果与对照组相比,内脏脂肪型肥胖组体重指数(BMI)、VFA、皮下脂肪面积(SFA)、VFA/SFA(V/S)、甘油三酯(TG)、甘油三酯葡萄糖指数(TyG)、UA、UHR水平升高,HDL-C水平降低,差异有统计学意义(均P<0.05)。Spearman相关分析显示,UHR与BMI、VFA、SFA、V/S、TG、TyG呈正相关(P<0.01)。以UHR为因变量,BMI、VFA、SFA、V/S、TG、TyG为自变量进行多元线性回归分析,结果显示TG、VFA是UHR的影响因素。ROC曲线显示UHR预测内脏脂肪型肥胖的曲线下面积为0.741(P<0.001),最佳截断值为0.35。结论健康体检人群UHR与VFA有关,对内脏脂肪型肥胖有较好的预测价值。

水平往复荷载作用下钢箱提篮拱弹塑性力学性能研究

目的 探究倾角、矢跨比及宽跨比三个参数对钢箱提篮拱在水平往复荷载作用下力学性能的影响,为钢提篮拱桥抗震设计提供理论基础。方法 通过改变参数,建立54个钢箱提篮拱有限元模型,在水平往复荷载作用下进行滞回分析,研究钢箱提篮拱水平力-位移滞回性能、极限承载力和拱顶横撑内力、变形在不同参数条件下的变化规律。结果 随着拱肋倾斜角度、宽跨比的增加或矢跨比的减小,结构初期刚度、极限承载能力均有较大提高,但横撑内力也随之增加,并会产生局部失稳破坏,影响结构的承载能力。结论 增加拱肋倾斜角度对钢箱提篮拱横向力学性能有较大改善,但在设计时应注意横撑内力增加带来的不利影响。

预燃室湍流射流点火甲醇发动机稀薄燃烧和排放特性试验研究

基于一台四冲程单缸发动机开展预燃室湍流射流点火(turbulent jet ignition,TJI)甲醇发动机燃烧特性、性能表现和排放特性的试验研究。结果表明,TJI燃烧模式燃烧速率较快,放热率(heat release rate,HRR)峰值明显较高,且具有更短的滞燃期和燃烧持续期。随着过量空气系数变大,缸内压力和放热率峰值变小,TJI和火花塞点火(spark ignition,SI)燃烧模式滞燃期和燃烧持续期均变长。此外,TJI燃烧模式可有效提升甲醇发动机的稀薄燃烧稳定性,可将稀燃极限拓展至过量空气系数2.0。TJI燃烧模式下平均指示压力略低于SI模式;然而对于过量空气系数大于1.1的稀燃工况,TJI燃烧模式指示燃油消耗率更低,在过量空气系数1.3时低于570 g/(kW·h),说明其具有更好的燃油经济性。TJI燃烧模式下氮氧化物排放量明显低于SI燃烧模式,过量空气系数1.1时降低约37.2%,并且在过量空气系数大于1.3的极稀燃工况具有相对较低的甲醛CH_(2)O和碳氢化合物排放。

宁夏某高校大学生瘦体组织成分与指长比的相关性研究

目的以宁夏某高校大学生为研究对象,分析瘦体组织(LBM)成分与指长比[食指(2D)︰环指(4D)]的相关性。方法随机选取838名在校大学生(男412名,女426名)为研究对象,采用生物电阻抗分析法测定所有受试者体重、身高、身体总水分(TBW)、细胞内液(ICW)、细胞外液(ECW)、蛋白质含量、骨矿物质含量(BMC)、骨骼肌含量(SMM)、体重指数(BMI)及基础代谢率(BMR)的分布。同时,拍摄受试者双手掌面照片,利用电脑图像软件测量并计算左、右手各2D︰4D。应用Pearson相关分析法及线性回归法分析各项LBM与2D︰4D的相关性。结果宁夏某高校大学生LBM、BMI和BMR的分布均表现为男性显著高于女性,差异有统计学意义(P<0.05);宁夏某高校大学生左手及右手2D︰4D均表现为女性显著高于男性,差异有统计学意义(P<0.05)。所有体成分指标在不同性别间均与2D︰4D无相关性(P>0.05)。结论宁夏某高校大学生LBM与2D︰4D均分别存在显著性别差异,提示性激素代谢水平可能影响二者的分布,然而两者之间并无相关性,可能并不存在共同的发育基础。

掺氢天然气非预混燃烧特性实验研究

以天然气掺氢技术为背景,构建一种非预混钝体同轴燃烧器及实验系统,测试了掺氢天然气(主要成分CH4)在不同燃料流速、掺氢比及当量比的火焰结构和污染物排放浓度,并考察了内构件对燃烧性能的影响。结果表明,掺氢后火焰高度降低,CO排放浓度降低,但NO_(x)排放浓度增加。当掺氢比达到80%时,与纯CH4相较,CO排放浓度降低93.5%,NO_(x)排放浓度增加1倍左右。随着燃料流速增加,火焰逐渐变长变宽,CO与NO_(x)排放浓度均增加;当量比<0.7时,随着当量比增加,燃烧室热损失降低,平均温度升高,CO排放浓度降低,而NO_(x)排放浓度增加;不同内构件的掺氢CH4燃烧性能差异较大,钝体—旋流内构件不仅可以降低51.9%的NO_(x)排放浓度,还可以增强燃烧的均匀程度及稳定性。研究结果对同轴燃烧器的设计、优化和应用具有参考意义,有助于推动天然气掺氢技术的发展。

双能X射线测定肉类肥瘦比例研究进展

近年来,我国肉类加工行业发展迅猛,自动化和智能化水平逐渐提高,多种肥瘦比例检测技术被应用到肉制品加工和屠宰行业。双能X射线吸收法(dual energy X-ray absorptiometry,DXA)是解决肉制品在线肥瘦比例检测的最佳方法之一,具有精准度高、耗时短、可以对胴体全身进行检测的优势。本文比较当前各种肥瘦比例检测技术的特点,介绍DXA的概念、测量方式,重点探讨DXA在肥瘦比例测定中的应用和研究进展,通过对研究现状、设备类型和存在问题的分析,讨论未来该技术应用的发展方向。

术后血糖联合胰腺-内脏脂肪CT值比对胰十二指肠切除术后胰瘘预测价值分析

目的研究胰十二指肠切除术(PD)后胰瘘(POPF)发生率与血糖及胰腺-内脏脂肪CT值比的相关性。方法选取2018年1月~2022年12月接受PD的病人94例,分析术前胰腺-内脏脂肪CT值比,检测术后1天血糖、血生化以及其他相关指标,单因素及多因素Logistic回归分析POPF发生的高危因素。结果94例病人中,POPF B/C级20例(21.3%)。Logistic回归分析结果显示,胰腺-内脏脂肪CT值比、术前淋巴细胞/单核细细胞、术后第1天血糖是PD病人术后POPF发生的危险因素;开腹手术是PD病人术后POPF发生的独立危险因素。胰腺-内脏脂肪CT值比预测POPF的灵敏度为0.80,特异度为0.58;术后第1天血糖预测POPF的灵敏度为0.55,特异度为0.84;二者联合预测POPF的灵敏度为0.60,特异度为0.78。结论胰腺-内脏脂肪CT值比联合术后第1天血糖可能成为预测PD病人POPF发生的危险因素。

Solution of idle LBO problem for high FAR aero combustor

The paper sheds light on the idle lean blow off(LBO)problem for high fuel air ratio(FAR)com⁃bustor,which is impossible to be addressed with traditional aero combustor design.A significant improvement in aero combustor design is required to resolve the idle LBO issue.The authors detailed a practical and efficient solu⁃tion,which not only solved the idle LBO issue but also defined the aero-thermal design for high-FAR combustor.The design will usher in a new era of aero combustor.