Dynamic analysis of growth of Salmonella Enteritidis in liquid egg whites

Salmonella Enteritidis (SE) is a common foodborne pathogen associated with eggs and egg products. This research was conducted to study the kinetics of growth and survival of SE in liquid egg whites (LEW). A dynamic temperature profile that exposed SE to suboptimal temperatures and below the minimum growth temperature (T_min) was used with two isothermal conditions to develop kinetic models. One-step dynamic analysis was used to directly construct a tertiary model for describing the growth and survival of SE and determine the kinetic parameters.The results of kinetic analysis showed that the T_min was 7.7 °C and SE may die off at a rate of 2.78 × 10⁻³ log CFU/ml per h per °C below the T_min. The root mean square error (RMSE) of the model was 0.5 log CFU/ml, with 76.6% of the residual errors within ±0.5 log CFU/ml of the experimental observations. The model was validated under both dynamic temperature and isothermal conditions. Both growth and survival of SE was accurately predicted, with the RMSE of validation at < 0.5 log CFU/ml. For all the validation tests, nearly 75% of the residual errors were within ±0.5 log CFU/ml of the experimental observations.This study clearly demonstrated that the one-step dynamic analysis method is an accurate and efficient method for direct construction of predictive models and estimation of the associated kinetic parameters that govern the growth and survival of microorganisms in food. Since the mathematical model has been validated, it can be used to predict the growth and survival of SE in LEW during storage and distribution and for conducting risk assessment of this microorganism.     

Effect of heat treatment on foaming properties of ostrich (Struthio camelus) egg white proteins

The effect of heat-treatment on foaming properties of ostrich albumen was investigated. At pH 7.5, coagulation of ovotransferrin (OT) resulted in minimum foaming capacity (FC) and maximum foam density (FD). While both exposure of sulfhydryl groups of ovalbumin (OV) and OT-OV interactions improved FC at lower pH, neither of them had beneficial effect on FC at pH 9. At pH 9, FC and FD were mildly affected by heat-treatment because of less aggregation of OT, then FC decreased due to covalent aggregates composed of ovomucin and OV, but at higher temperatures, higher level of OV unfolding resulted in enhanced FC.     

新钢9号高炉浅铁口维护生产实践

对新钢9号高炉铁口深度合格率偏低的原因进行分析,通过采取严格控制炮泥质量、规范操作、加强管理等措施,浅铁口现象明显改善.     

渤海海域浅层油气运移新认识与勘探新进展

浅层新近系是渤海海域油田储量和产量的主要层系。随着勘探程度的提高，大—中型油气田发现的难度也越来越大。基于渤海海域的勘探实践，结合浅层大—中型油田源外成藏的特性，通过分析油气深层运移与浅层富集的耦合关系，明确了古近系烃源层油气初次、二次运移所形成的"汇聚脊"对其上浅层油气富集、聚集的控制作用，并根据输导体系的组合划分出油气汇聚样式。在"汇聚脊"控藏模式的指导下，渤海海域多个构造带的油气勘探都取得突破，获得一系列亿吨级新发现，由此保证了渤海海域浅层规模优质油气储量持续发现，指导后续勘探进展。     

障板上矩形薄板在浅水环境中的振动及声辐射解析分析

通过推导得到浅水环境中矩形板声辐射阻抗矩阵的解析表达,进一步结合振动假设模态方法及辐射表面单元辐射器思想求解浅水环境中矩形板的振动响应,分析水深对矩形板模态附加质量的影响,给出矩形板模态附加质量随水深的变化情况,得到波导模态的激发对附加质量的影响,并通过对辐射抗矩阵的特征分析得到附加质量在板上分布的主要模式;进一步结合声辐射模态辐射效率,分析水深变化对矩形板振动响应峰值及远场声辐射的影响,分析结果表明:水深度变化对振动响应峰值及声辐射功率的影响与第1阶声辐射模态的辐射效率随深度的变化具有一致性。     

Diet-derived vicilins detected in eggs laid by a double-mated female Callosobruchus maculatus originate from nuptial gifts donated by both male partners

The eggshell and the cement that attaches the eggs of the seed-beetle Callosobruchus maculatus to the seeds of cowpea (Vigna unguiculata) contain vicilins, the main storage protein found in seeds. These proteins are derived from both males and females, which originally sequester them during the larval phase from their seed hosts. In this test, females received vicilin from different males during mating as a seminal nuptial gift, and transmitted this sequestered blend of proteins to the eggs. The presence of vicilin in the cement and eggshell was demonstrated by light microscopy and Western blotting. Quantification using ELISA showed that the concentration of vicilin from seminal vesicles of a virgin male is approximately double that measured following the first copula to a virgin female, suggesting that the investment of vicilin by the males is very important. This is the first demonstration showing that at least two different males can make a direct contribution of a sequestered protein which is used in oogenesis.     

浅埋偏压软弱围岩大断面隧道综合处治措施

针对某隧道开挖断面大、地质条件差、Ⅳ级、Ⅴ级围岩所占比例大等特点,施工过程中发生过塌方、地表沉降、溶洞、特大溶洞、软弱围岩收敛变形超限,分别采用针对性的综合处治措施,顺利通过了出口长大浅埋偏压地段,取得了十分满意的效果。     

Competitiveness of shallow water hydrocarbon development projects in Mexico after 2015 actualization of fiscal reforms: Economic benchmark of new production sharing agreement versus typical U.S. federal lease terms

Development of Mexican hydrocarbon reservoirs by foreign operators has become possible under Mexico's new Hydrocarbon Law, effective as per January 2015. Our study compares the economic returns of shallow water fields in the Gulf of Mexico applying the royalty and taxes due under the fiscal regimes of the U.S. and Mexico. The net present value (NPV) of the base case scenario is US$1.4 billion, assuming standard development and production cost (opex, capex), 10% discount rate accounting for the cost of capital and revenues computed using a reference oil price of $75/bbl. The impact on NPV of oil price volatility is accounted for in a sensitivity analysis. The split of the NPV of shallow water hydrocarbon assets between the two contractual parties, contractor and government, in Mexico and the U.S. is hugely different. Our base case shows that for similar field assets, Mexico's production sharing agreement allocates about $1,150 million to the government and $191 million to the contractor, while under U.S. license conditions the government take is about $700 million and contractor take is $553 million. The current production sharing agreement leaves some marginal shallow water fields in Mexico undeveloped for reasons detailed and quantified in our study.     

Lipid‐lowering mechanism of egg yolk in normal rats

The ingestion of egg has been reported to lower blood cholesterol, but the mechanism is unclear. Here, the biochemical metabolic mechanism by which the oral administration of egg yolk affects blood lipid reduction was investigated using normal rats. Blood triglycerides and total cholesterol were lower and high‐density lipoprotein cholesterol was higher in an egg yolk‐given group compared to other groups, while low‐density lipoprotein cholesterol was increased in the pork belly oil‐given group. HMG‐CoA reductase activity was higher in the pork belly oil‐given group, compared to an egg yolk‐given group, a weekly alternating administration of pork belly oil and egg yolk‐given group, and the saline‐given normal control group. However, faecal excretions of total sterol, neutral sterol and acid sterol in an egg yolk‐given group were higher compared to the pork belly oil‐given group, a weekly alternating administration of pork belly oil and egg yolk‐given group, and a normal control group. The results suggested that ingestion of egg decreased blood lipids.     

Effects of controlled water temperatures on oviposition in a lotic‐breeding and externally fertilizing salamander (Hynobius kimurae)

Warm or cool ambient temperatures during winter generate plasticity in the within‐year timing of oviposition or breeding phenology shifts through the use of a reaction norm in many riverine ectotherms, but within‐year timing of oviposition in Hynobius kimurae (Caudata: Hynobiidae) is predicted to be constant at different water temperatures of a mountain stream. To clarify this difference, by experimentally controlling water temperatures from fall to spring and thus changing durations of aquatic hibernation and dates of oviposition, we determined whether oviposition is more advanced when water temperatures increase earlier than usual or is more delayed when water temperatures increase later than usual. Oviposition was more delayed than usual with earlier exposure to high water temperatures during spring and was earlier than usual with exposing to higher water temperatures during hibernation. Days from submergence to oviposition were responsive to cumulative daily water temperatures from submergence to oviposition within a population. A rate of increase in days from submergence to oviposition was different between populations but was constant within a population even if minimal water temperatures varied each year. When running a program of a Markov chain Monte Carlo generalized linear mixed model for Bayesian computation to interpret confounding effects, neither different treatments nor different years statistically affected days from submergence to oviposition. These results suggest that a biological clock exits for days from submergence to oviposition in H. kimurae, which could allow survival in situations with either warmer or cooler environments.