Development of two screening duplex PCR assays for genetically modified organism quantification using multiplex real-time PCR master mixes

Since 2001, the traceability and labelling of genetically modified organism (GMO) food and feed derived products are obligatory in the European Union. Genetically modified organisms (GMO) are commonly detected via PCR tests. These tests typically involve several steps: (1) screening (2) construct specific (3) event specific and (4) reference gene. Screening tests are based on sequences frequently used for GM development, allowing for the detection of a large number of GMOs. To improve GMO detection efficiency, using specific multiplex master mixes, we developed two real-time PCR screening duplex PCR assays for the detection of P35S/Tnos and Pnos/T35S sequences. By combining these tests, we were able to reduce the time and cost of analysis. For the Pnos/T35S duplex, good sensitivity was obtained using one of the mixes compared to the others. Both duplexes had 100% specificity when tested on DNA from GM maize, rapeseed and soybean. When the duplexes were tested on DNA containing various amounts of GM maize and soybean, the corresponding targets were detected. The detection limit of our methods was found to be between 2 and 8 haploid genome copies for both P35S/Tnos and Pnos/T35S tests. In summary, with high efficiency and good linearity, the proposed two screening duplexes allow for more efficient GMO detection.     

ESR牙齿珐琅质测年中不同拟合函数对古剂量测定的影响

本文对单饱和指数(SSE)拟合函数、双饱和指数(DSE)拟合函数、指数加线性(EPL)拟合函数进行了讨论,并对重庆巫山龙骨坡早更新世遗址的8颗哺乳动物牙齿化石的古剂量作了对比研究.结果显示,SSE函数的古剂量拟合结果高于DSE和EPL函数,且拟合残差也较大.与已知参考剂量比较后发现,DSE函数拟合结果的相对偏差最小,SSE函数与参考值的偏差最大.实验说明,对于早期地点的牙齿化石样品采用SSE拟合函数会造成古剂量的高估,DSE的拟合结果更接近样品的真实古剂量.     

Effect of dry heating on the microbiological quality,functional properties,and natural bacteriostatic ability of egg white after reconstitution

Spray-dried egg white (powder) is widely used in the food industry because of its variety of functional properties and its practical advantages. Moreover, egg white powder is generally considered safe because it can withstand high temperatures that allow for the destruction of all pathogens, especially Salmonella. In France, two types of treatments are used to improve the functional properties (whipping and gelling) of dried egg white: standard storage at 67 degrees C for about 15 days and storage at 75 to 80 degrees C for 15 days. The objective of this study was to investigate the effects of two dry-heating treatments (storage at 67 and 75 degrees C for 15 days) on the subsequent ability of egg white to resist Salmonella growth after reconstitution. The impact on the endogenous microflora of the powder and on its functional properties was also considered. Both dry-heating treatments were efficient in destroying a large number of Salmonella. Dry heating at 75 degrees C affected the bacteriostatic ability of reconstituted egg white to a greater extent than did dry heating at 67 degrees C. This loss of bacteriostatic ability could be attributable to the thermal denaturation of ovotransferrin, resulting in a reduction in its activity as an iron chelator. However, dry heating at 75 degrees C resulted in improved functional properties. Ultimately, no complete compromise between better functional quality and the preservation of the bacteriostatic ability of egg white after reconstitution is possible. Our results underline the importance of the use of hygienic conditions with egg white powder, especially with powder subjected to high-temperature treatments.     

Multi-level analysis of low-cost Z-pinned composite joints: Part 1: Single Z-pin behaviour

In the framework of the EU program ALCAS (advanced low-cost aircraft structure), a new Z-pinning technique was developed by EADS Innovation Works. It was used to manufacture low-cost Z-pinned junction demonstrators (L and T shaped specimens) typical of aeronautical structures. In order to understand load transfer mechanisms in this kind of assembly, a multi-level analysis was performed. Firstly, tension and shear pin behaviour was investigated as well as pin pull-out from net resin. It was demonstrated that the mechanical transfer is mainly through bonding, even when the pins are twisted. Secondly, an analytical model was proposed which predicts the maximum load capacity of a single pin. Finally this study provides the basis for a design methodology to compute ultimate loads of Z-pinned junctions under complex loading.     

Characterization of film failures by bismuth electrodeposition—Application to thin deformed fluorocarbon films for stent applications

A new approach for the detection and visualization of nano-scaled film defects, such as fissures and holes is described. The procedure is based on a selective electrochemical deposition of bismuth onto uncovered parts of stainless steel substrates due to film cracking after deformation. Cyclic voltammetry experiments enabled the identification of the bismuth redox signals, necessary for the subsequent potentiostatic electrodeposition. A combination of XPS and ToF-SIMS analyses demonstrated that deposition with commonly used acidified electrolytes led to a significant film degradation, by defluorination and chain scission. When an identical procedure was performed in neutral conditions, which was realized by the addition of a bismuth chelating agent, no influence onto the integrity of the fluorocarbon coatings was observed. By SEM, XPS and ToF-SIMS analyses, the deposition of bismuth on the film defects was clearly demonstrated and the failures were evidenced. The identification of nano-scaled coating failures, which was extremely difficult before using common characterization tools, was now realized. This work makes part of a strategy to cover stent materials with a protective fluorocarbon layer and to examine the influence of stent expansion onto the film cohesive properties.     

Core crush criterion to determine the strength of sandwich composite structures subjected to compression after impact

In this study a core crush criterion is proposed to determine the residual strength of impacted sandwich structures. The core of the sandwich is made of a Nomex Honeycomb core and the faces are laminated and remain thin. The mechanism of failure of this kind of structure under post-impact compressive loading is due to interaction between three mechanical behaviors: geometrical nonlinearity due to the skin’s neutral line off-set in the dent area, nonlinear response of the core and damages to the skins. For the type of sandwich analysed in this study, initially the core crushes at the apex of the damage. Using a finite element discrete modelling of the core previously proposed by the authors, the load corresponding to the crushing of the first cell can be computed and it gives the value of the residual strength for our criterion. Some geometric and material hypotheses are assumed in the damaged area mainly based on non-destructive inspection (NDI). The criterion is then applied to tests modelled by Lacy and Hwang [Lacy TE, Hwang Y. Numerical modelling of impact-damaged sandwich composites subjected to compression after impact loading. Compos Struct 2003;61:115–128]. It is shown that the criterion allows a good prediction of the tests except in the case of very small dents. Several sensitivity studies on the assumptions were made and it is shown that using this approach, the criterion is robust.     

Microwave-based biosensor for on-chip biological cell analysis

This paper presents an innovative biosensing technique, based on the interaction between biomaterial and microwave electromagnetic (EM) waves, which probes the bio-parameters of investigated biological samples. Thanks to the microtechnologies, this approach is able to sense biomaterials down to living cells size without invasivity. The broadband dielectric spectroscopy of living cells suspensions is therefore demonstrated, sketching a rich EM signature, “rich” in terms of biological information’s such as cells’ proliferation and cells’ viability. Capacitive contrasts of 4 and 12 % between the cells suspension and their pure medium are measured at 20 and 40 GHz respectively, which demonstrate the ability of such a technique to detect (and quantify) living cells non-invasively. Moreover, we demonstrate a capacitive contrast of 5 % at 30 GHz between living and dead cells. Such a result is based on the ability of the microwaves to penetrate into the cells and sense their intracellular content, and then to carry viability information’s of biomaterials out. Finally, we present the feasibility of on-chip microwave signals processing, which points out that integrated circuit for data processing can be integrated together with a nano-liter range microfluidic bio-sample manipulation and a microwave-based biosensor. Such a work consequently permits to envision promising Lab-on-Chip applications such as cells’ drug screening for personalized medicine notably.     

Estimation of the conditional risk in classification: The swapping method

The bias of the empirical error rate in supervised classification is studied. It is shown that this bias can be understood as a covariance between the classification rule and the labeling of the training data. From this result, a new penalized criterion is proposed to perform model selection in classification. Applications of the resulting algorithm to simulated and real data are presented.     

On the Fastest Vickrey Algorithm

We investigate the algorithmic performance of Vickrey-Clarke-Groves mechanisms in the single item case. We provide a formal definition of a Vickrey algorithm for this framework, and give a number of examples of Vickrey algorithms. We consider three performance criteria, one corresponding to a Pareto criterion, one to worst-case analysis, and one related to first-order stochastic dominance. We show that Pareto best Vickrey algorithms do not exist and that worst-case analysis is of no use in discriminating between Vickrey algorithms. For the case of two bidders, we show that the bisection auction stochastically dominates all Vickrey algorithms. We extend our analysis to the study of weak Vickrey algorithms and winner determination algorithms. For the case of two bidders, we show that the One-Search algorithm stochastically dominates all column monotonic weak Vickrey algorithms and that a suitably adjusted version of the bisection algorithm, the WD bisection algorithm, stochastically dominates all winner determination algorithms. The WD bisection algorithm Pareto dominates all column monotonic winner determination algorithms in the n bidder case.