Effects of environmental factors and agricultural techniques on antioxidantcontent of tomatoes

Antioxidants are believed to be important in the prevention of diseases such as cancer and cardiovascular disease. Lycopene is one of the main antioxidants to be found in fresh tomatoes and processed tomato products. The lycopene content also accounts for the redness of the fruit, which is one of the main qualities for which industry and consumers now look. Other carotenes (such as β‐carotene), vitamin C, vitamin E and various phenolic compounds are also thought to be health‐promoting factors with antioxidant properties. Since the antioxidant content of tomatoes may depend on genetic factors, the choice of variety cultivated may affect the results at harvest. To be able to control the antioxidant content of tomatoes at the field level when growing a given variety, it is necessary to know the effects of both environmental factors and the agricultural techniques used. Temperatures below 12 °C strongly inhibit lycopene biosynthesis and temperatures above 32 °C stop this process altogether. The effects of the temperature on the synthesis of other antioxidants have not yet been properly assessed. The effects of light have been studied more thoroughly, apart from those on vitamin E. The effects of water availability, mineral nutrients (nitrogen, phosphorus, potassium and calcium) and plant growth regulators have been studied, but results are sometimes contradictory and the data often incomplete. During the ripening period, lycopene content of tomatoes increases sharply from the pink stage onwards, but no sufficient attempts have been made so far to assess the changes in the other antioxidants present in the fruit. This paper reviews the present state of the art. Copyright © 2003 Society of Chemical Industry     

Treatment of hemorrhages by rupture of cardio-tuberous varices with transjugular intrahepatic portasystemic shunt

Twelve consecutive patients admitted for bleeding from ruptured gastric varices were treated with transjugular intrahepatic portosystemic shunts and followed for a mean of 6 +/- 3 months (range: 8-293 days). The shunt was performed successfully in all 12 patients. The shunt occluded in 3 patients (respectively 19, 101 and 103 days after insertion) of whom one remained asymptomatic and two experienced rebleeding. Four patients presented with acute encephalopathy, spontaneously in two and after rebleeding in two. Three patients died, two after rebleeding and one of septic shock secondary to pneumonia. Overall, 9 patients survived a mean of 211 +/- 92 days with no rebleeding, 8 of whom have not yet experienced any complications. These results suggest that transjugular intrahepatic portosystemic shunts could be useful in treating hemorrhages from ruptured gastric varices and in preventing their recurrence.     

A fast,single-layer,area router for semi-custom analogue circuits

This paper describes the router developed for ALPS, the analogue layout prototyping system. the ALPS router employs some classic techniques and contributes a new, fast implementation of a maze-running algorithm and a new algorithm for finding two disjoint paths in a graph (the so-called ‘two path problem’). Discussion of these points is coupled with a review of existing routing algorithms and techniques, and comparisons where possible.     

Two applications of a numerical approach of heat transfer process within rock beds

A general method for solving the differential equations describing the heat transfer process within a rock bed is presented. A numerical model accounting for secondary phenomena such as thermal losses and conduction effect is developed. The results of the study are presented in the form of curves and empirical equations. Two applications of this theoretical model are then investigated. One is the elaboration of a new calculation method for the volumetric convective heat transfer coefficient using the compared results of theoretical modeling and experimental tests. The second application is a design method for solar applications of rock-bed storage with determination of optimal values for parameters such as air velocity, particle diameter and geometrical aspects of the storage unit.     

Fatigue crack initiation and propagation in austenitic stainless steels for light water reactors

The determination of fatigue life of components containing defects usually takes into account crack propagation only. In a real situation, a number of cycles are often required to reach fatigue crack initiation and predictive evaluation of fatigue crack initiation phases of real defects in austenitic stainless steel welded joints are presented. Fatigue crack growth rates in wrought and cast austenitic stainless steels and associated welds are also presented. Effects of various mechanical parameters (R ratio and variable amplitude loading) of a PWR environment and of metallurgical factors (δ ferrite content and ageing in cast austenitic stainless steels) are discussed.     

Microstructure and Nanoscale Piezoelectric/Ferroelectric Properties in La2Ti2O7 Thin Films Grown on (110)‐Oriented Doped Nb:SrTiO3 Substrates

(00l)‐Oriented La₂Ti₂O₇ (LTO) thin films with monoclinic perovskite‐layer structure [a = 7.806(2) Å, b = 5.552(3) Å, c = 13.015(5) Å, β = 98.62(2)°] have been grown by a sol–gel route on conducting (110)‐oriented doped Nb:SrTiO₃ (STO) substrates. The narrow rocking curves (0.24° width for 004_LTO peak) demonstrate the sharp mosaïcity of the films. Using high‐resolution X‐ray diffraction (HR‐XRD), epitaxial relationships between the LTO, and the STO substrate are given. In addition, HR‐XRD evidences the existence of (212)‐oriented crystallites 1.5° disoriented with respect to the plane of the substrate. We confirm, by DFT calculations, that the polarization vector lies in the b‐axis of the LTO cell and consequently, the existence of these (212)‐oriented crystallites enables to explain the origin of the various contrasts observed both on the in‐plane and out‐of‐plane images when collected by piezoresponse force microscopy. Finally, both successful poling experiments performed via the tip of atomic force microscope and the existence of local piezoloops within the domains, unambiguously confirm the ferroelectric state of the films at the nanoscale level. Once again, this study demonstrates that a clear understanding of nanoscale piezoelectric/ferroelectric phenomena in oriented thin films passes through a carefully structural analysis as performed by HR‐XRD.     

Toughening of epoxy matrices with reduced single-walled carbon nanotubes

Reduced single-walled carbon nanotubes (r-SWCNT) are shown to react readily at room temperature under inert atmosphere conditions with epoxide moieties, such as those in triglycidyl p-amino phenol (TGAP), to produce a soft covalently bonded interface around the SWCNT. The soft interface is compatible with the SWCNT-free cross-linked cured matrix and acts as a toughener for the composite. Incorporation of 0.2 wt % r-SWCNT enhances the ultimate tensile strength, toughness and fracture toughness by 32, 118, and 40%, respectively, without change in modulus. A toughening rate (dK(IC)/dwt(f)) of 200 MPa m(0.5) is obtained. The toughening mechanism is elucidated through dynamic mechanical analyses, Raman spectroscopy and imaging, and stress-strain curve analyses. The method is scalable and applicable to epoxy resins and systems used commercially.     

Reproducing the experimental pull-out and shear strength of clinched sheet metal connections using FEA

Clinching, commonly referred to as press-joining, is a mechanical joining technique which involves severe local plastic deformation of two or more sheet metal parts resulting in a permanent mechanical interlock or joint. This interlock is achieved by using simple tools like a die, a punch and a blank holder. Since no additional elements are used, the strength of the clinched connection is entirely determined by the clinch geometry, and, consequently, by the geometry of die and punch. As a result, for each combination of material and sheet thickness an optimal geometry of the tools can be derived. This can be done either through extensive experimental testing or, more cost-effectively, with the aid of numerical simulations. However, for these results to be useful they have to be able to reproduce the experimental strength of the connection. In this paper we investigate the possibility of predicting the shear and pull-out strength of a clinched sheet metal assembly using FEA. Numerical difficulties associated with these simulations and the preceding forming operation are discussed. A comparison between experimental data and simulation is provided.     

State of the art of high temperature power electronics

High temperature power electronics has become possible with the recent availability of silicon carbide devices. This material, as other wide-bandgap semiconductors, can operate at temperatures above 500 °C, whereas silicon is limited to 150-200 °C. Applications such as transportation or a deep oil and gas wells drilling can benefit. A few converters operating above 200 °C have been demonstrated, but work is still ongoing to design and build a power system able to operate in harsh environment (high temperature and deep thermal cycling).     

Sources of self-efficacy: An investigation of elementary school students in France.

The purpose of this study was to assess the influence of Bandura's (1997) theorized sources of self-efficacy on the academic and self-regulatory efficacy beliefs of 3rd-grade elementary school students (N = 395) in France, to examine whether classroom context might explain a significant portion of the variation in self-efficacy, and to assess whether these sources differ as a function of sex. Hierarchical linear modeling revealed that mastery experience, social persuasions, and mean classroom-level self-efficacy predicted mathematics self-efficacy. Mastery experience, social persuasions, physiological state, and mean classroom-level self-efficacy predicted French self-efficacy. All 4 sources predicted self-efficacy for self-regulated learning in both subjects, with the exception of vicarious experience in French. Classroom-level variables did not predict self-efficacy for self-regulated learning in either subject. Boys outperformed girls in mathematics and reported higher mathematics self-efficacy, self-regulatory efficacy, mastery experience, social persuasions, and lower physiological arousal. In French, girls outperformed boys but reported lower self-efficacy. Findings support and refine the theoretical tenets of Bandura's social cognitive theory. (PsycINFO Database Record (c) 2011 APA, all rights reserved)