Gas Turbines are among the most important energy systems for aviation and thermal-based power generation.The performance of gas turbine intakes with S-shaped diffusers is vulnerable to flow separation,reversal flow,an...Gas Turbines are among the most important energy systems for aviation and thermal-based power generation.The performance of gas turbine intakes with S-shaped diffusers is vulnerable to flow separation,reversal flow,and pressure distortion,mainly in aggressive S-shaped diffusers.Severalmethods,including vortex generators and energy promoters,have been proposed and investigated both experimentally and numerically.This paper compiles a review of experimental investigations that have been performed and reported to mitigate flow separation and restore system performance.The operational principles,classifications,design geometries,and performance parameters of Sshaped diffusers are presented to facilitate the analysis and understanding of the influence of each mitigation method on flowenhancement in S-shaped diffusers.Theinfluencing design parameters on the performance of the S-shaped diffuser and the findings achieved by various experimental investigations are discussed and compared.The review concludes that reducing the intake length reduces the size and weight of the gas turbine,leading to a higher power-to-weight ratio.However,the main challenge in shortening the S-shaped diffusers is the flow separation in the high-curvature section,which must be prevented to maintain high performance.Prevention can be achieved through flow control methods,which are categorized into passive and aggressive methods.The static pressure recovery coefficient,total pressure loss coefficient,ideal static pressure coefficient,distortion coefficient,and skin friction coefficient are the primary performance evaluation and comparison parameters between the experimentally investigated mitigation methods.The new trend in S-shaped diffuser studies includes the integration of computational and data-driven methods.展开更多
Based on the discussion of the multi-level intake application status of high dam reservoir,this paper takes the Jinping-I hydropower project reservoir in the Yalong River as an example,which is shaped by the highest 3...Based on the discussion of the multi-level intake application status of high dam reservoir,this paper takes the Jinping-I hydropower project reservoir in the Yalong River as an example,which is shaped by the highest 305 m high arch dam,and carries out the forecasting research on the reservoir temperature by numerical simulation and physical model testing.This paper studies the intake effect of withdrawing the surface warm water by the stoplog gates inlets and verifies the reliability of the mathematical model by comparative analysis.The results show that for a high dam hydropower station,taking the appropriate multi-level intake measure can withdraw the surface warm water in the spawning season and provide a favorable environment for the fish reproduction.Innovative technical ideas and implementation scheme are adopted in this research.It can provide technical reference for the solutions of similar problems in the future and it also has important engineering significance on the research of water temperature in large deep reservoirs.展开更多
Lifestyle is related to many chronic diseases,such as knee osteoarthritis(KOA).Food intake is important because it can be controlled.However,the causal relationship of food intake and KOA still remain unclear.To ident...Lifestyle is related to many chronic diseases,such as knee osteoarthritis(KOA).Food intake is important because it can be controlled.However,the causal relationship of food intake and KOA still remain unclear.To identify the relationship between food intake and KOA and to screen relevant targets.First,we performed two-sample Mendelian randomization(MR)analysis.A total of 16 kinds of food intake datasets were included,the inverse variance-weighted analysis showed that the KOA was negatively correlated with cereal intake(odds ratio(OR)0.48;95%CI 0.35-0.68;P=1.98×10−5).Second,potential drug targets of KOA in plasma were explored,secreted protein acidic and rich in cysteine(SPARC,or osteonectin),SPARC,Cwcv,and Kazal-like domains proteoglycan 2(SPOCK2)as the causal protein for plasma with KOA,and increased SPOCK2(OR 0.84;95%CI 0.77-0.92;P=5.52×10−5),decreased the risk of KOA.Integrated transcriptomic analysis(P=0.0285)and in vivo(P=0.0395)showed consistent results.Finally,by metabolomics analysis and molecular docking,seven co-expressed small molecules were detected in cereal and were bound to SPOCK2.Our findings indicate the cereal intake was negatively correlated with KOA,and support the SPOCK2 as a novel potential target for cereal intake in KOA.Our study will provide a clinical dietary guidance for KOA patients and a theoretical basis for the development of novel,side-effect-free drugs for KOA.展开更多
The intake system of a racing engine plays a crucial role in determining its performance,particularly in terms of volumetric efficiency,power output,and throttle response.According to Formula Society of Automotive Eng...The intake system of a racing engine plays a crucial role in determining its performance,particularly in terms of volumetric efficiency,power output,and throttle response.According to Formula Society of Automotive Engineers(FSAE)regulations,the engine intake systemmust incorporate a 20mmdiameter flow-limiting valve within the intake manifold.This restriction significantly reduces the airflow into the engine,leading to a substantial drop in power output.To mitigate this limitation,the intake system requires a redesign.In this study,theoretical calculations and one-dimensional thermodynamic simulations are employed to determine the optimal parameters for the intake system.A numerical simulation of the intake system’s flow field is then conducted to refine its structure and layout.Finally,experiments are performed on an engine equipped with the optimized intake system,and its feasibility is evaluated based on experimental results.Thefindings indicate that the maximumengine torque increases from56.36 to 59.91 N⋅m,while the maximum power output rises from 59.16 to 63.94 kW.To further enhance performance and adaptability across different competitions,a variable-length intakemanifold control system is also designed,improving both power delivery and overall operational stability of the racing car.展开更多
Objective This study aimed to reexplore minimum iodine excretion and to build a dietary iodine recommendation for Chinese adults using the obligatory iodine loss hypothesis.Methods Data from 171 Chinese adults(19–21 ...Objective This study aimed to reexplore minimum iodine excretion and to build a dietary iodine recommendation for Chinese adults using the obligatory iodine loss hypothesis.Methods Data from 171 Chinese adults(19–21 years old)were collected and analyzed based on three balance studies in Shenzhen,Yinchuan,and Changzhi.The single exponential equation was accordingly used to simulate the trajectory of 24 h urinary iodine excretion as the low iodine experimental diets offered(iodine intake:11-26μg/day)and to further deduce the dietary reference intakes(DRIs)for iodine,including estimated average requirement(EAR)and recommended nutrient intake(RNI).Results The minimum iodine excretion was estimated as 57,58,and 51μg/day in three balance studies,respectively.Moreover,it was further suggested as 57,58,and 51μg/day for iodine EAR,and 80,81,and 71μg/day for iodine RNI or expressed as 1.42,1.41,and 1.20μg/(day·kg)of body weight.Conclusion The iodine DRIs for Chinese adults were established based on the obligatory iodine loss hypothesis,which provides scientific support for the amendment of nutrient requirements.展开更多
BACKGROUND Bariatric surgery is an effective treatment for severe obesity but is associated with an increased risk for development of eating disorders.Indeed,numerous maladaptive eating behaviors and eating disorders ...BACKGROUND Bariatric surgery is an effective treatment for severe obesity but is associated with an increased risk for development of eating disorders.Indeed,numerous maladaptive eating behaviors and eating disorders have been described following bariatric surgery.However,the differentiation of pathologic eating patterns from expected dietary changes following bariatric surgery can sometimes be difficult to discern.CASE SUMMARY A female in her early 40s presented for medical stabilization of severe protein calorie malnutrition after losing 52.3 kg over the last six months after Roux-en-Y gastric bypass,with subsequent development of cyclic nausea and vomiting.Fear of these aversive physical symptoms led to further restriction of nutritional intake and weight loss.The patient was diagnosed with avoidant/restrictive food intake disorder,which has not been previously reported after bariatric surgery.CONCLUSION Improvement in the diagnostic nomenclature for feeding and eating disorders is warranted for patients who have undergone bariatric surgery.展开更多
This study addresses the issue of spray icing on the air intake grilles of ship power systems in cold maritime environments.Through numerical simulation methods,the influence of environmental parameters on icing chara...This study addresses the issue of spray icing on the air intake grilles of ship power systems in cold maritime environments.Through numerical simulation methods,the influence of environmental parameters on icing characteristics is revealed,and an energy-efficient zoned electric heating anti-icing strategy is proposed.A threedimensional grille model is constructed to systematically analyze the effects of environmental temperature(from−20℃to−4℃),droplet diameter(from 50μm to 500μm),and liquid water content(from 0.5 g/m³to 8 g/m³)on icing rates and blockage of the flow channel.The results indicate that low temperature and high liquid water content significantly exacerbate icing.Under the condition of an environmental temperature of−20℃,droplet diameter of 500μm,and liquid water content of 8 g/m³,the flow channel blockage ratio reaches 30.95%within 10 min.Additionally,as droplet diameter increases,the droplet impingement and icing regions become more concentrated toward the leading edge of blades.To mitigate grille icing in cold environments,an electric heating film configuration is employed for thermal protection.Optimization of the heating strategy reveals that the zoned heating approach,compared to the initial uniform heating scheme,effectively homogenizes surface temperature distribution while reducing total power consumption by 37.47%.This study validates the engineering applicability of the zoned electric heating anti/de-icing strategy,providing theoretical and technical support for the design of anti-icing systems in ship power systems operating in cold maritime regions.展开更多
Purpose Athletes have presented a deficiency in relative energy in recent years,which calls for appropriate nutritional guid-ance based on the estimated energy requirement(EER)-the target amount of daily energy intake...Purpose Athletes have presented a deficiency in relative energy in recent years,which calls for appropriate nutritional guid-ance based on the estimated energy requirement(EER)-the target amount of daily energy intake(EI).The calculation of EER requires longitudinal physical activity level(PAL)data,which has received insufficient attention.Therefore,this study aimed to clarify the changes in PAL by training periodization using the doubly labeled water(DLW)method,combined with the current status of EI by competition characteristics.Methods The participants comprised four male sprint athletes and five male endurance athletes at the national level.The experimental periods were normal training(NT)and tapering training(TT)periods.PAL was measured using the DLW method,and EI was measured by the dietary record method.Results PAL of the sprint athletes in the NT periods was significantly higher than in TT periods.EI had no significant differ-ences between the two periods.PAL and EI of the endurance athletes had no significant differences beteen the two periods.Conclusions These findings indicated that in sprint athletes,different PAL was observed between the two periods,with the TT period suggesting a lower value than the NT period.In endurance athletes,it had similar PAL values between the two periods.This suggests that the degree of influence of the training period on PAL may vary depending on the athletic events.Furthermore,the EI was not adjusted for changes in PAL,and the participants observed the status of energy-deficient regardless of discipline or training period.展开更多
AIM:To investigate the causal relationship between dietary intake and myopia using Mendelian randomization(MR)analysis.METHODS:Genome-wide association study(GWAS)data from the IEU Open GWAS database were utilized to e...AIM:To investigate the causal relationship between dietary intake and myopia using Mendelian randomization(MR)analysis.METHODS:Genome-wide association study(GWAS)data from the IEU Open GWAS database were utilized to examine associations between myopia and various dietary factors.MR analysis,incorporating both univariable and multivariable approaches,assessed the impact of food intake on myopia risk through five analytical methods,with inverse variance weighted(IVW)serving as the primary reference.Sensitivity analyses,including heterogeneity assessment,horizontal pleiotropy evaluation,and leave-oneout analysis,were conducted to validate the MR findings.RESULTS:Univariable MR analysis identified a causal link between food intake and myopia.Consumption of breaded fish,canned soup,sweet biscuits,and certain fruits correlated with a lower risk of myopia,whereas intake of low-calorie hot chocolate and cereal was associated with an increased risk.Multivariable MR analysis further confirmed that breaded fish consumption exerted a direct protective effect against myopia,particularly when consumed alongside other dietary components.These findings highlight the intricate interplay between specific dietary factors and myopia development,offering valuable insights for further research.CONCLUSION:MR analysis provides evidence supporting a potential causal relationship between breaded fish intake and myopia,underscoring its relevance in targeted myopia prevention strategies.展开更多
Industry and energy continue to require piston engines(PICE)at a high level worldwide.Therefore,science and technology must urgently work on improving the PICE working cycle.Improving the quality of the intake process...Industry and energy continue to require piston engines(PICE)at a high level worldwide.Therefore,science and technology must urgently work on improving the PICE working cycle.Improving the quality of the intake process of theworking fluid into the cylinder is one of the most effective ways to improve the operational performance of PICE.The purpose of the study was to assess the impact of various cylinder head(CylH)designs on the gas-dynamic and heat-exchange qualities of air flows within an engine model’s intake system.Three different CylH designs were studied:the basic configuration and upgraded cylinder heads with a square valve and a square valve port.These designs are innovative.Laboratory conditions were used to conduct the studies for stationary air flow.The experiments covered the range of Reynolds numbers from 8500 to 96,000.The intake system’s gas dynamics and heat transfer were determined using the thermal anemometry method,which was based on constant-temperature hot-wire anemometers.It has been established that the use of upgraded CylHs causes an increase in the turbulence number of flow by an average of 13.5%.Additionally,itwas found that the increase in the turbulence number of flowin the cylinder is about 19%when installing new CylH designs.It was shown that therewas an increase in the heat transfer coefficient in the intake pipe by 10%–40%when installing modernized CylH designs in the intake system.The article focused on the problems of increasing the turbulence level and intensifying the heat transfer of stationary air flow in the intake system,specifically in PICEs.The study’s findings are novel in the areas of applied gas dynamics and PICEs.展开更多
BACKGROUND Metabolic dysfunction-associated steatotic liver disease(MASLD)is a common and increasingly prevalent condition in the Middle East,but its determinants in the region are underexplored.Diet and lifestyle are...BACKGROUND Metabolic dysfunction-associated steatotic liver disease(MASLD)is a common and increasingly prevalent condition in the Middle East,but its determinants in the region are underexplored.Diet and lifestyle are known to significantly influence MASLD progression.AIM To assess energy and nutrient intake among MASLD patients living in Qatar and evaluate their dietary patterns.METHODS Using a cross-sectional design,94 Arab patients with MASLD,aged≥18 years,living in Qatar were studied.MASLD was diagnosed using ultrasonography,fibro scan,or elastography.Sociodemographic information was collected using a self-administered questionnaire.Dietary intake was assessed through three 24-hour recalls and a qualitative food frequency questionnaire.Energy,macro-,and micronutrient intake were analyzed using Elizabeth Stewart Hands and Associates Food Processor®Nutrition Analysis software.Statistical analyses,including factor loadings were performed using STATA 18.RESULTS Compared to recommended dietary allowance,MASLD patients had high intakes of fat,saturated fat,and cholesterol.They also showed reduced intakes of vitamin K in men,and vitamins E and A(retinol),calcium and magnesium in both genders,while selenium and sodium intakes were higher than recommendations.Three dietary patterns were identified:The‘Traditional Qatari food’pattern,the‘Prudent’pattern,and the‘Fast-food’pattern.However,no significant associations were found between these dietary patterns and body mass index or low-density lipoprotein,using adjusted regression models.CONCLUSION Findings warrant replication in longitudinal studies and call for dietary interventions to reduce energy density and enhance overall diet quality,including micronutrient intake,for MASLD prevention and management in the region.展开更多
Iodine is an essential element for the synthesis of thyroid hormones.Iodine deficiency increases the burden on thyroid function and causes harm to health.The identification of convenient and reliable biomarkers for as...Iodine is an essential element for the synthesis of thyroid hormones.Iodine deficiency increases the burden on thyroid function and causes harm to health.The identification of convenient and reliable biomarkers for assessing iodine nutritional status is essential for evaluating iodine intake.Urinary iodine concentration(UIC)is commonly used for population level iodine status assessment but is less reliable for individuals.A 24-h urine sample is more accurate but difficult to collect[1].Thyroid volume(Tvol)and goiter rate are suitable for evaluating the long-term iodine nutritional status in populations[2].Blood indicator collection is an invasive procedure.展开更多
The influence of different solution and aging conditions on the microstructure,impact toughness,and crack initiation and propagation mechanisms of the novel α+β titanium alloy Ti6422 was systematically investigated....The influence of different solution and aging conditions on the microstructure,impact toughness,and crack initiation and propagation mechanisms of the novel α+β titanium alloy Ti6422 was systematically investigated.By adjusting the furnace cooling time after solution treatment and the aging temperature,Ti6422 alloy samples were developed with a multi-level lamellar microstructure,in-cluding microscaleαcolonies and α_(p) lamellae,as well as nanoscale α_(s) phases.Extending the furnace cooling time after solution treatment at 920℃ for 1 h from 240 to 540 min,followed by aging at 600℃ for 6 h,increased the α_(p) lamella content,reduced the α_(s) phase content,expanded theαcolonies and α_(p) lamellae size,and improved the impact toughness from 22.7 to 53.8 J/cm^(2).Additionally,under the same solution treatment,raising the aging temperature from 500 to 700℃ resulted in a decrease in the α_(s) phase content and a growth in the thickness of the α_(p) lamella and α_(s) phase.The impact toughness increased significantly with these changes.Samples with high α_(p) lamellae content or large α_(s) phase size exhibited high crack initiation and propagation energies.Impact deformation caused severe kinking of the α_(p) lamellae in crack initiation and propagation areas,leading to a uniform and high-density kernel average misorientation(KAM)distribu-tion,enhancing plastic deformation coordination and uniformity.Moreover,the multidirectional arrangement of coarserαcolonies and α_(p) lamellae continuously deflect the crack propagation direction,inhibiting crack propagation.展开更多
The intake swirl in the cylinder was induced by a swirler which was fixed in one of two intake ports. In order to understand the characteristics of the intake swirl, a transparent water analog was designed which simul...The intake swirl in the cylinder was induced by a swirler which was fixed in one of two intake ports. In order to understand the characteristics of the intake swirl, a transparent water analog was designed which simulated 150 type single cylinder engine. At the same time, the particle image velocimetry was used to measure the flow fields induced by various swirlers in the analog. After measurement, a new method was presented to evaluate the intensity of the intake swirl. Then, when the measured sections, the lifts of valve and the swirlers were different, the calculated results of the flow field were compared.展开更多
This paper aims to explore the role of intake in second language learning.Based on her literature review and the case of an English lesson in a Chinese secondary school,the author argues that L2 acquisition does not t...This paper aims to explore the role of intake in second language learning.Based on her literature review and the case of an English lesson in a Chinese secondary school,the author argues that L2 acquisition does not take place directly from input to output.In each sqecific part of L2 acquisition process,intake plays various important roles such as filtering,facilitating in comprehensible input and processing in pushed output.In the Chinese foreign language teaching context,it is also found that L2 acquisition is an arduous task for learners to extract information from the input,utilize it in forming a grammar and produce target language forms accurately and fluently.It is the same with L2 teachers who need to play their roles of a controller,a corrector,an organizer and a prompter in the learning process.展开更多
To eliminate the shrinkage porosity in low pressure casting of an A356 aluminum alloy intake manifold casting, numerical simulation on fi lling and solidifi cation processes of the casting was carried out using the Pr...To eliminate the shrinkage porosity in low pressure casting of an A356 aluminum alloy intake manifold casting, numerical simulation on fi lling and solidifi cation processes of the casting was carried out using the ProCAST software. The gating system of the casting is optimized according to the simulation results. Results show that when the gating system consists of only one sprue, the fi lling of the molten metal is not stable; and the casting does not follow the sequence solidifi cation, and many shrinkage porosities are observed through the casting. After the gating system is improved by adding one runner and two in-gates, the fi lling time is prolonged from 4.0 s to 4.5 s, the fi lling of molten metal becomes stable, but this casting does not follow the sequence solidifi cation either. Some shrinkage porosity is also observed in the hot spots of the casting. When the gating system was further improved by adding risers and chill to the hot spots of the casting, the shrinkage porosity defects were eliminated completely. Finally, by using the optimized gating system the A356 aluminum alloy intake manifold casting with integrated shape and smooth surface as well as dense microstructure was successfully produced.展开更多
Objective The present study aimed to investigate the association of red meat usual intake with metabolic syndrome(Met S),and explore the contribution of red meat usual intake to serum ferritin.Methods Based on the dat...Objective The present study aimed to investigate the association of red meat usual intake with metabolic syndrome(Met S),and explore the contribution of red meat usual intake to serum ferritin.Methods Based on the data from the longitudinal China Health and Nutrition Survey(CHNS),2,797 healthy adults aged 18–75 years without hypertension,diabetes,and Met S were selected in 2009 as subjects and follow-up studies were carried out till 2015.We used the National Cancer Institute(NCI)method to estimate the usual intake of foods.Multivariable logistic regressions were performed to evaluate the association between red meat usual intake and the risk of Met S.Quantile regression analysis was used to study the relationship between red meat consumption and serum ferritin levels.Results After adjusting for potential confounders,red meat,and fresh red meat were positively associated with the risk of Met S(RR=1.41,95%CI:1.05–1.90 and RR=1.37,95%CI:1.02–1.85,respectively).These relationships showed increasing trend(P<0.05).The level of serum ferritin increased significantly with the number of Met S components(P<0.05).The quantile regression analysis showed that red meat and fresh red meat usual intake had a significant positive association with serum ferritin levels across the entire conditional serum ferritin distribution(P<0.05).Processed red meat did not exhibit a similar association.Conclusion Higher red meat usual intake was associated with an increased risk of Met S and elevated serum ferritin levels.展开更多
Background: Residual feed intake(RFI) is an inheritable measure of feed efficiency that is independent on level of production. However, physiological and metabolic mechanisms underlying divergent RFI are not fully elu...Background: Residual feed intake(RFI) is an inheritable measure of feed efficiency that is independent on level of production. However, physiological and metabolic mechanisms underlying divergent RFI are not fully elucidated.This study was conducted to investigate dietary nitrogen(N) partitioning and microbial protein synthesis in lactating dairy cows divergent in phenotypic RFI.Results: Thirty Holstein dairy cows(milk yield = 35.3 ± 4.71 kg/d;milk protein yield = 1.18 ± 0.13 kg/d;mean ± standard deviation) were selected for the experiment to derive RFI. After the RFI measurement period of 50 d, the 10 lowest RFI cows and 8 highest RFI cows were selected. The low RFI cows had lower dry matter intake(DMI, P < 0.05) than the high RFI cows, but they produced similar energy-corrected milk. The ratios of milk to DMI(1.41 vs. 1.24, P < 0.01) and energy-corrected milk to DMI(1.48 vs. 1.36, P < 0.01) were greater in low RFI cows than those in the high RFI cows. The low RFI cows had lower milk urea nitrogen than that in the high RFI cows(P = 0.05). Apparent digestibility of nutrients did not differ between two groups(P > 0.10). Compared with high RFI animals, the low RFI cows had a lower retention of N(5.72 vs. 51.4 g/d, P < 0.05) and a higher partition of feed N to milk N(29.7% vs. 26.5%, P < 0.05).Conclusions: The results suggest that differences in N partition, synthesis of microbial protein, and utilization of metabolizable protein could be part of the mechanisms associated with variance in the RFI.展开更多
Objective To explore whether the intake of dietary carotenoids could protect against skeletal fluorosis in Guizhou province in which coal-burning fluorosis is endemic. Methods A case-control study of 196 patients with...Objective To explore whether the intake of dietary carotenoids could protect against skeletal fluorosis in Guizhou province in which coal-burning fluorosis is endemic. Methods A case-control study of 196 patients with skeletal fluorosis and 196 age and gender-matched controls was conducted in Zhijin, Guizhou Province. Face-to-face interviews were conducted to assess habitual dietary intake using a 75-item food frequency questionnaire and various covariates with structured questionnaires. Urinary fluoride was measured using an ion-selective electrode method. The genotype of superoxide dismutase 2（SOD2） rs11968525 was detected by Taq Man method. Results We observed significant dose-dependent inverse associations of skeletal fluorosis with intake of β-carotene, lutein/zeaxanthin, lycopene, and total carotenoids（P-trend = 0.002 to 0.018）, whereas α-carotene and β-cryptoxanthin intakes were not found to be related to skeletal fluorosis, after adjustment for potential confounders. The adjusted ORs and 95% CI of skeletal fluorosis for the highest versus lowest quartile were 0.30（0.10, 0.86） for β-carotene, 0.23（0.08, 0.66） for lycopene, 0.26（0.10, 0.75） for lutein/zeaxanthin and 0.34（0.14, 0.74） for total carotenoids（all P-trend ＆lt; 0.05）. Stratified analyses showed that the protective effects of lutein/zeaxanthin and total carotenoids on skeletal fluorosis were more evident for individuals with the AG＋AA genotypes of SOD2（rs11968525）. Conclusion Increased intakes of β-carotene, lutein/zeaxanthin, lycopene, and total carotenoids are independently associated with a lower risk of coal-burning skeletal fluorosis. SOD2（rs11968525） polymorphisms might modify the inverse associations between dietary carotenoids and skeletal fluorosis.展开更多
Objective Nan'ao County in Guandong Province is a high-risk area of esophageal cancer in Southern China. Of the suspected etiological factors in the environment, N-nitrosamines and their precursors have received t...Objective Nan'ao County in Guandong Province is a high-risk area of esophageal cancer in Southern China. Of the suspected etiological factors in the environment, N-nitrosamines and their precursors have received the greatest attention. Methods Sixty samples of the diet ingested by the inhabitants were collected and detected for volatile N-nitrosamines and their precursors. Five N-nitrosamines detected by Gas Chromatography-Thermal Energy Analyzer were N-nitrosodimethylamine, N-nitrosodiethylamine, N-nitrosopyrrolidine, N-nitrosopiperidine and N-nitrosomethyl-benzylamine. Results The average content of 5 volatile N-nitrosamines in the diet was 312.0 μg/kg (median). The daily intake of the nitrosamines was 286.5 μg/head/day. Only the ability to exogenously synthesize N-nitrosopiperidine was powerful among 5 volatile N-nitrosamines. By a computerized stepwise regression analysis and curve fitting, we studied the correlation among the nitrosamines, the precursors and the major food items in the samples. Conclusion It demonstrated that a relatively high content of volatile N-nitrosamines was present in the diet collected in the area.展开更多
文摘Gas Turbines are among the most important energy systems for aviation and thermal-based power generation.The performance of gas turbine intakes with S-shaped diffusers is vulnerable to flow separation,reversal flow,and pressure distortion,mainly in aggressive S-shaped diffusers.Severalmethods,including vortex generators and energy promoters,have been proposed and investigated both experimentally and numerically.This paper compiles a review of experimental investigations that have been performed and reported to mitigate flow separation and restore system performance.The operational principles,classifications,design geometries,and performance parameters of Sshaped diffusers are presented to facilitate the analysis and understanding of the influence of each mitigation method on flowenhancement in S-shaped diffusers.Theinfluencing design parameters on the performance of the S-shaped diffuser and the findings achieved by various experimental investigations are discussed and compared.The review concludes that reducing the intake length reduces the size and weight of the gas turbine,leading to a higher power-to-weight ratio.However,the main challenge in shortening the S-shaped diffusers is the flow separation in the high-curvature section,which must be prevented to maintain high performance.Prevention can be achieved through flow control methods,which are categorized into passive and aggressive methods.The static pressure recovery coefficient,total pressure loss coefficient,ideal static pressure coefficient,distortion coefficient,and skin friction coefficient are the primary performance evaluation and comparison parameters between the experimentally investigated mitigation methods.The new trend in S-shaped diffuser studies includes the integration of computational and data-driven methods.
基金supported by the National Natural Science Foundation of China and EHDC Yalong River Joint Research Foundation of Hydropower Development Project(Grant No.50639070)
文摘Based on the discussion of the multi-level intake application status of high dam reservoir,this paper takes the Jinping-I hydropower project reservoir in the Yalong River as an example,which is shaped by the highest 305 m high arch dam,and carries out the forecasting research on the reservoir temperature by numerical simulation and physical model testing.This paper studies the intake effect of withdrawing the surface warm water by the stoplog gates inlets and verifies the reliability of the mathematical model by comparative analysis.The results show that for a high dam hydropower station,taking the appropriate multi-level intake measure can withdraw the surface warm water in the spawning season and provide a favorable environment for the fish reproduction.Innovative technical ideas and implementation scheme are adopted in this research.It can provide technical reference for the solutions of similar problems in the future and it also has important engineering significance on the research of water temperature in large deep reservoirs.
基金supported by the National Natural Science Foundation of China(82072432)Scientific Research and Innovation Platform for Intelligent and Precise Treatment of Bone and Joint Diseases in Shaanxi Province(2024PT-13)Key Project of Shaanxi Provincial Natural Science Foundation(2024JC-ZDXM-55).
文摘Lifestyle is related to many chronic diseases,such as knee osteoarthritis(KOA).Food intake is important because it can be controlled.However,the causal relationship of food intake and KOA still remain unclear.To identify the relationship between food intake and KOA and to screen relevant targets.First,we performed two-sample Mendelian randomization(MR)analysis.A total of 16 kinds of food intake datasets were included,the inverse variance-weighted analysis showed that the KOA was negatively correlated with cereal intake(odds ratio(OR)0.48;95%CI 0.35-0.68;P=1.98×10−5).Second,potential drug targets of KOA in plasma were explored,secreted protein acidic and rich in cysteine(SPARC,or osteonectin),SPARC,Cwcv,and Kazal-like domains proteoglycan 2(SPOCK2)as the causal protein for plasma with KOA,and increased SPOCK2(OR 0.84;95%CI 0.77-0.92;P=5.52×10−5),decreased the risk of KOA.Integrated transcriptomic analysis(P=0.0285)and in vivo(P=0.0395)showed consistent results.Finally,by metabolomics analysis and molecular docking,seven co-expressed small molecules were detected in cereal and were bound to SPOCK2.Our findings indicate the cereal intake was negatively correlated with KOA,and support the SPOCK2 as a novel potential target for cereal intake in KOA.Our study will provide a clinical dietary guidance for KOA patients and a theoretical basis for the development of novel,side-effect-free drugs for KOA.
基金supported by the Key Laboratory of Automotive Power Train and Electronics(Hubei University of Automotive Technology)(ZDK1201505)Auto Parts TechnologyHubei Province Collaborative Innovation Project(2015XTZX04).
文摘The intake system of a racing engine plays a crucial role in determining its performance,particularly in terms of volumetric efficiency,power output,and throttle response.According to Formula Society of Automotive Engineers(FSAE)regulations,the engine intake systemmust incorporate a 20mmdiameter flow-limiting valve within the intake manifold.This restriction significantly reduces the airflow into the engine,leading to a substantial drop in power output.To mitigate this limitation,the intake system requires a redesign.In this study,theoretical calculations and one-dimensional thermodynamic simulations are employed to determine the optimal parameters for the intake system.A numerical simulation of the intake system’s flow field is then conducted to refine its structure and layout.Finally,experiments are performed on an engine equipped with the optimized intake system,and its feasibility is evaluated based on experimental results.Thefindings indicate that the maximumengine torque increases from56.36 to 59.91 N⋅m,while the maximum power output rises from 59.16 to 63.94 kW.To further enhance performance and adaptability across different competitions,a variable-length intakemanifold control system is also designed,improving both power delivery and overall operational stability of the racing car.
基金supported by the National Natural Science Foundation of China(Grant No.81872624)Fundamental Research Program of Shanxi Province(Grant No.202403021211139).
文摘Objective This study aimed to reexplore minimum iodine excretion and to build a dietary iodine recommendation for Chinese adults using the obligatory iodine loss hypothesis.Methods Data from 171 Chinese adults(19–21 years old)were collected and analyzed based on three balance studies in Shenzhen,Yinchuan,and Changzhi.The single exponential equation was accordingly used to simulate the trajectory of 24 h urinary iodine excretion as the low iodine experimental diets offered(iodine intake:11-26μg/day)and to further deduce the dietary reference intakes(DRIs)for iodine,including estimated average requirement(EAR)and recommended nutrient intake(RNI).Results The minimum iodine excretion was estimated as 57,58,and 51μg/day in three balance studies,respectively.Moreover,it was further suggested as 57,58,and 51μg/day for iodine EAR,and 80,81,and 71μg/day for iodine RNI or expressed as 1.42,1.41,and 1.20μg/(day·kg)of body weight.Conclusion The iodine DRIs for Chinese adults were established based on the obligatory iodine loss hypothesis,which provides scientific support for the amendment of nutrient requirements.
文摘BACKGROUND Bariatric surgery is an effective treatment for severe obesity but is associated with an increased risk for development of eating disorders.Indeed,numerous maladaptive eating behaviors and eating disorders have been described following bariatric surgery.However,the differentiation of pathologic eating patterns from expected dietary changes following bariatric surgery can sometimes be difficult to discern.CASE SUMMARY A female in her early 40s presented for medical stabilization of severe protein calorie malnutrition after losing 52.3 kg over the last six months after Roux-en-Y gastric bypass,with subsequent development of cyclic nausea and vomiting.Fear of these aversive physical symptoms led to further restriction of nutritional intake and weight loss.The patient was diagnosed with avoidant/restrictive food intake disorder,which has not been previously reported after bariatric surgery.CONCLUSION Improvement in the diagnostic nomenclature for feeding and eating disorders is warranted for patients who have undergone bariatric surgery.
基金supported in part by the Ship Preliminary Research Project (No.3020401020102)。
文摘This study addresses the issue of spray icing on the air intake grilles of ship power systems in cold maritime environments.Through numerical simulation methods,the influence of environmental parameters on icing characteristics is revealed,and an energy-efficient zoned electric heating anti-icing strategy is proposed.A threedimensional grille model is constructed to systematically analyze the effects of environmental temperature(from−20℃to−4℃),droplet diameter(from 50μm to 500μm),and liquid water content(from 0.5 g/m³to 8 g/m³)on icing rates and blockage of the flow channel.The results indicate that low temperature and high liquid water content significantly exacerbate icing.Under the condition of an environmental temperature of−20℃,droplet diameter of 500μm,and liquid water content of 8 g/m³,the flow channel blockage ratio reaches 30.95%within 10 min.Additionally,as droplet diameter increases,the droplet impingement and icing regions become more concentrated toward the leading edge of blades.To mitigate grille icing in cold environments,an electric heating film configuration is employed for thermal protection.Optimization of the heating strategy reveals that the zoned heating approach,compared to the initial uniform heating scheme,effectively homogenizes surface temperature distribution while reducing total power consumption by 37.47%.This study validates the engineering applicability of the zoned electric heating anti/de-icing strategy,providing theoretical and technical support for the design of anti-icing systems in ship power systems operating in cold maritime regions.
基金supported by the Japan Society for the Promotion of Science,Grant Numbers JP 24700723,JP 17K13209.
文摘Purpose Athletes have presented a deficiency in relative energy in recent years,which calls for appropriate nutritional guid-ance based on the estimated energy requirement(EER)-the target amount of daily energy intake(EI).The calculation of EER requires longitudinal physical activity level(PAL)data,which has received insufficient attention.Therefore,this study aimed to clarify the changes in PAL by training periodization using the doubly labeled water(DLW)method,combined with the current status of EI by competition characteristics.Methods The participants comprised four male sprint athletes and five male endurance athletes at the national level.The experimental periods were normal training(NT)and tapering training(TT)periods.PAL was measured using the DLW method,and EI was measured by the dietary record method.Results PAL of the sprint athletes in the NT periods was significantly higher than in TT periods.EI had no significant differ-ences between the two periods.PAL and EI of the endurance athletes had no significant differences beteen the two periods.Conclusions These findings indicated that in sprint athletes,different PAL was observed between the two periods,with the TT period suggesting a lower value than the NT period.In endurance athletes,it had similar PAL values between the two periods.This suggests that the degree of influence of the training period on PAL may vary depending on the athletic events.Furthermore,the EI was not adjusted for changes in PAL,and the participants observed the status of energy-deficient regardless of discipline or training period.
基金Supported by Xi’an Science and Technology Program Project(No.24YXYJ0108)Support Projects of Xi’an Children’s Hospital(No.2024I07).
文摘AIM:To investigate the causal relationship between dietary intake and myopia using Mendelian randomization(MR)analysis.METHODS:Genome-wide association study(GWAS)data from the IEU Open GWAS database were utilized to examine associations between myopia and various dietary factors.MR analysis,incorporating both univariable and multivariable approaches,assessed the impact of food intake on myopia risk through five analytical methods,with inverse variance weighted(IVW)serving as the primary reference.Sensitivity analyses,including heterogeneity assessment,horizontal pleiotropy evaluation,and leave-oneout analysis,were conducted to validate the MR findings.RESULTS:Univariable MR analysis identified a causal link between food intake and myopia.Consumption of breaded fish,canned soup,sweet biscuits,and certain fruits correlated with a lower risk of myopia,whereas intake of low-calorie hot chocolate and cereal was associated with an increased risk.Multivariable MR analysis further confirmed that breaded fish consumption exerted a direct protective effect against myopia,particularly when consumed alongside other dietary components.These findings highlight the intricate interplay between specific dietary factors and myopia development,offering valuable insights for further research.CONCLUSION:MR analysis provides evidence supporting a potential causal relationship between breaded fish intake and myopia,underscoring its relevance in targeted myopia prevention strategies.
文摘Industry and energy continue to require piston engines(PICE)at a high level worldwide.Therefore,science and technology must urgently work on improving the PICE working cycle.Improving the quality of the intake process of theworking fluid into the cylinder is one of the most effective ways to improve the operational performance of PICE.The purpose of the study was to assess the impact of various cylinder head(CylH)designs on the gas-dynamic and heat-exchange qualities of air flows within an engine model’s intake system.Three different CylH designs were studied:the basic configuration and upgraded cylinder heads with a square valve and a square valve port.These designs are innovative.Laboratory conditions were used to conduct the studies for stationary air flow.The experiments covered the range of Reynolds numbers from 8500 to 96,000.The intake system’s gas dynamics and heat transfer were determined using the thermal anemometry method,which was based on constant-temperature hot-wire anemometers.It has been established that the use of upgraded CylHs causes an increase in the turbulence number of flow by an average of 13.5%.Additionally,itwas found that the increase in the turbulence number of flowin the cylinder is about 19%when installing new CylH designs.It was shown that therewas an increase in the heat transfer coefficient in the intake pipe by 10%–40%when installing modernized CylH designs in the intake system.The article focused on the problems of increasing the turbulence level and intensifying the heat transfer of stationary air flow in the intake system,specifically in PICEs.The study’s findings are novel in the areas of applied gas dynamics and PICEs.
文摘BACKGROUND Metabolic dysfunction-associated steatotic liver disease(MASLD)is a common and increasingly prevalent condition in the Middle East,but its determinants in the region are underexplored.Diet and lifestyle are known to significantly influence MASLD progression.AIM To assess energy and nutrient intake among MASLD patients living in Qatar and evaluate their dietary patterns.METHODS Using a cross-sectional design,94 Arab patients with MASLD,aged≥18 years,living in Qatar were studied.MASLD was diagnosed using ultrasonography,fibro scan,or elastography.Sociodemographic information was collected using a self-administered questionnaire.Dietary intake was assessed through three 24-hour recalls and a qualitative food frequency questionnaire.Energy,macro-,and micronutrient intake were analyzed using Elizabeth Stewart Hands and Associates Food Processor®Nutrition Analysis software.Statistical analyses,including factor loadings were performed using STATA 18.RESULTS Compared to recommended dietary allowance,MASLD patients had high intakes of fat,saturated fat,and cholesterol.They also showed reduced intakes of vitamin K in men,and vitamins E and A(retinol),calcium and magnesium in both genders,while selenium and sodium intakes were higher than recommendations.Three dietary patterns were identified:The‘Traditional Qatari food’pattern,the‘Prudent’pattern,and the‘Fast-food’pattern.However,no significant associations were found between these dietary patterns and body mass index or low-density lipoprotein,using adjusted regression models.CONCLUSION Findings warrant replication in longitudinal studies and call for dietary interventions to reduce energy density and enhance overall diet quality,including micronutrient intake,for MASLD prevention and management in the region.
基金supported by the National Natural Science Foundation of China(Grant numbers 82204041)Gansu Provincial Science and Technology Program Funded Projects(Grant numbers 22JR11RA184).
文摘Iodine is an essential element for the synthesis of thyroid hormones.Iodine deficiency increases the burden on thyroid function and causes harm to health.The identification of convenient and reliable biomarkers for assessing iodine nutritional status is essential for evaluating iodine intake.Urinary iodine concentration(UIC)is commonly used for population level iodine status assessment but is less reliable for individuals.A 24-h urine sample is more accurate but difficult to collect[1].Thyroid volume(Tvol)and goiter rate are suitable for evaluating the long-term iodine nutritional status in populations[2].Blood indicator collection is an invasive procedure.
基金supported by the National Natural Science Foundation of China(No.52090041).
文摘The influence of different solution and aging conditions on the microstructure,impact toughness,and crack initiation and propagation mechanisms of the novel α+β titanium alloy Ti6422 was systematically investigated.By adjusting the furnace cooling time after solution treatment and the aging temperature,Ti6422 alloy samples were developed with a multi-level lamellar microstructure,in-cluding microscaleαcolonies and α_(p) lamellae,as well as nanoscale α_(s) phases.Extending the furnace cooling time after solution treatment at 920℃ for 1 h from 240 to 540 min,followed by aging at 600℃ for 6 h,increased the α_(p) lamella content,reduced the α_(s) phase content,expanded theαcolonies and α_(p) lamellae size,and improved the impact toughness from 22.7 to 53.8 J/cm^(2).Additionally,under the same solution treatment,raising the aging temperature from 500 to 700℃ resulted in a decrease in the α_(s) phase content and a growth in the thickness of the α_(p) lamella and α_(s) phase.The impact toughness increased significantly with these changes.Samples with high α_(p) lamellae content or large α_(s) phase size exhibited high crack initiation and propagation energies.Impact deformation caused severe kinking of the α_(p) lamellae in crack initiation and propagation areas,leading to a uniform and high-density kernel average misorientation(KAM)distribu-tion,enhancing plastic deformation coordination and uniformity.Moreover,the multidirectional arrangement of coarserαcolonies and α_(p) lamellae continuously deflect the crack propagation direction,inhibiting crack propagation.
文摘The intake swirl in the cylinder was induced by a swirler which was fixed in one of two intake ports. In order to understand the characteristics of the intake swirl, a transparent water analog was designed which simulated 150 type single cylinder engine. At the same time, the particle image velocimetry was used to measure the flow fields induced by various swirlers in the analog. After measurement, a new method was presented to evaluate the intensity of the intake swirl. Then, when the measured sections, the lifts of valve and the swirlers were different, the calculated results of the flow field were compared.
文摘This paper aims to explore the role of intake in second language learning.Based on her literature review and the case of an English lesson in a Chinese secondary school,the author argues that L2 acquisition does not take place directly from input to output.In each sqecific part of L2 acquisition process,intake plays various important roles such as filtering,facilitating in comprehensible input and processing in pushed output.In the Chinese foreign language teaching context,it is also found that L2 acquisition is an arduous task for learners to extract information from the input,utilize it in forming a grammar and produce target language forms accurately and fluently.It is the same with L2 teachers who need to play their roles of a controller,a corrector,an organizer and a prompter in the learning process.
基金supported by the National Natural Science Foundation of China(No.51204124)the China Postdoctoral Science Foundation(No.2012M511610)the Scientific Research Foundation of Wuhan Institute of Technology(No.14125041)
文摘To eliminate the shrinkage porosity in low pressure casting of an A356 aluminum alloy intake manifold casting, numerical simulation on fi lling and solidifi cation processes of the casting was carried out using the ProCAST software. The gating system of the casting is optimized according to the simulation results. Results show that when the gating system consists of only one sprue, the fi lling of the molten metal is not stable; and the casting does not follow the sequence solidifi cation, and many shrinkage porosities are observed through the casting. After the gating system is improved by adding one runner and two in-gates, the fi lling time is prolonged from 4.0 s to 4.5 s, the fi lling of molten metal becomes stable, but this casting does not follow the sequence solidifi cation either. Some shrinkage porosity is also observed in the hot spots of the casting. When the gating system was further improved by adding risers and chill to the hot spots of the casting, the shrinkage porosity defects were eliminated completely. Finally, by using the optimized gating system the A356 aluminum alloy intake manifold casting with integrated shape and smooth surface as well as dense microstructure was successfully produced.
基金funded by the Ministry of Finance of the People’s Republic of China[No.13103110700015005]Carolina Population Center[No.P2CHD050924,T32 HD007168]+1 种基金the University of North Carolina at Chapel Hill,the NIH[No.R01-HD30880,DK056350,R24 HD050924,and R01-HD38700]the NIH Fogarty International Center[No.D43TW009077,D43 TW007709].
文摘Objective The present study aimed to investigate the association of red meat usual intake with metabolic syndrome(Met S),and explore the contribution of red meat usual intake to serum ferritin.Methods Based on the data from the longitudinal China Health and Nutrition Survey(CHNS),2,797 healthy adults aged 18–75 years without hypertension,diabetes,and Met S were selected in 2009 as subjects and follow-up studies were carried out till 2015.We used the National Cancer Institute(NCI)method to estimate the usual intake of foods.Multivariable logistic regressions were performed to evaluate the association between red meat usual intake and the risk of Met S.Quantile regression analysis was used to study the relationship between red meat consumption and serum ferritin levels.Results After adjusting for potential confounders,red meat,and fresh red meat were positively associated with the risk of Met S(RR=1.41,95%CI:1.05–1.90 and RR=1.37,95%CI:1.02–1.85,respectively).These relationships showed increasing trend(P<0.05).The level of serum ferritin increased significantly with the number of Met S components(P<0.05).The quantile regression analysis showed that red meat and fresh red meat usual intake had a significant positive association with serum ferritin levels across the entire conditional serum ferritin distribution(P<0.05).Processed red meat did not exhibit a similar association.Conclusion Higher red meat usual intake was associated with an increased risk of Met S and elevated serum ferritin levels.
基金supported by grants from the National Natural Science Foundation of China(No.31872380)the China Agricultural Research System(Beijing,China No.CARS-36)
文摘Background: Residual feed intake(RFI) is an inheritable measure of feed efficiency that is independent on level of production. However, physiological and metabolic mechanisms underlying divergent RFI are not fully elucidated.This study was conducted to investigate dietary nitrogen(N) partitioning and microbial protein synthesis in lactating dairy cows divergent in phenotypic RFI.Results: Thirty Holstein dairy cows(milk yield = 35.3 ± 4.71 kg/d;milk protein yield = 1.18 ± 0.13 kg/d;mean ± standard deviation) were selected for the experiment to derive RFI. After the RFI measurement period of 50 d, the 10 lowest RFI cows and 8 highest RFI cows were selected. The low RFI cows had lower dry matter intake(DMI, P < 0.05) than the high RFI cows, but they produced similar energy-corrected milk. The ratios of milk to DMI(1.41 vs. 1.24, P < 0.01) and energy-corrected milk to DMI(1.48 vs. 1.36, P < 0.01) were greater in low RFI cows than those in the high RFI cows. The low RFI cows had lower milk urea nitrogen than that in the high RFI cows(P = 0.05). Apparent digestibility of nutrients did not differ between two groups(P > 0.10). Compared with high RFI animals, the low RFI cows had a lower retention of N(5.72 vs. 51.4 g/d, P < 0.05) and a higher partition of feed N to milk N(29.7% vs. 26.5%, P < 0.05).Conclusions: The results suggest that differences in N partition, synthesis of microbial protein, and utilization of metabolizable protein could be part of the mechanisms associated with variance in the RFI.
基金supported by the National Natural Science Foundation of China[grant number 81460497]
文摘Objective To explore whether the intake of dietary carotenoids could protect against skeletal fluorosis in Guizhou province in which coal-burning fluorosis is endemic. Methods A case-control study of 196 patients with skeletal fluorosis and 196 age and gender-matched controls was conducted in Zhijin, Guizhou Province. Face-to-face interviews were conducted to assess habitual dietary intake using a 75-item food frequency questionnaire and various covariates with structured questionnaires. Urinary fluoride was measured using an ion-selective electrode method. The genotype of superoxide dismutase 2（SOD2） rs11968525 was detected by Taq Man method. Results We observed significant dose-dependent inverse associations of skeletal fluorosis with intake of β-carotene, lutein/zeaxanthin, lycopene, and total carotenoids（P-trend = 0.002 to 0.018）, whereas α-carotene and β-cryptoxanthin intakes were not found to be related to skeletal fluorosis, after adjustment for potential confounders. The adjusted ORs and 95% CI of skeletal fluorosis for the highest versus lowest quartile were 0.30（0.10, 0.86） for β-carotene, 0.23（0.08, 0.66） for lycopene, 0.26（0.10, 0.75） for lutein/zeaxanthin and 0.34（0.14, 0.74） for total carotenoids（all P-trend ＆lt; 0.05）. Stratified analyses showed that the protective effects of lutein/zeaxanthin and total carotenoids on skeletal fluorosis were more evident for individuals with the AG＋AA genotypes of SOD2（rs11968525）. Conclusion Increased intakes of β-carotene, lutein/zeaxanthin, lycopene, and total carotenoids are independently associated with a lower risk of coal-burning skeletal fluorosis. SOD2（rs11968525） polymorphisms might modify the inverse associations between dietary carotenoids and skeletal fluorosis.
基金The study was supported by grant of the research project of science and technology of the Provincial Higher Education Office, the Provincial Health Office and Li Ka-shing's endowment.
文摘Objective Nan'ao County in Guandong Province is a high-risk area of esophageal cancer in Southern China. Of the suspected etiological factors in the environment, N-nitrosamines and their precursors have received the greatest attention. Methods Sixty samples of the diet ingested by the inhabitants were collected and detected for volatile N-nitrosamines and their precursors. Five N-nitrosamines detected by Gas Chromatography-Thermal Energy Analyzer were N-nitrosodimethylamine, N-nitrosodiethylamine, N-nitrosopyrrolidine, N-nitrosopiperidine and N-nitrosomethyl-benzylamine. Results The average content of 5 volatile N-nitrosamines in the diet was 312.0 μg/kg (median). The daily intake of the nitrosamines was 286.5 μg/head/day. Only the ability to exogenously synthesize N-nitrosopiperidine was powerful among 5 volatile N-nitrosamines. By a computerized stepwise regression analysis and curve fitting, we studied the correlation among the nitrosamines, the precursors and the major food items in the samples. Conclusion It demonstrated that a relatively high content of volatile N-nitrosamines was present in the diet collected in the area.
