Vitamin C Enhances Vitamin E Status and Reduces Oxidative Stress Indicators in Sea Bass Larvae Fed High DHA Microdiets

Docosahexaenoic acid (DHA) is an essential fatty acid necessary for many biochemical, cellular and physiological functions in fish. However, high dietary levels of DHA increase free radical injury in sea bass (Dicentrarchus labrax) larvae muscle, even when vitamin E (α-tocopherol, α-TOH) is increased. Therefore, the inclusion of other nutrients with complementary antioxidant functions, such as vitamin C (ascorbic acid, vitC), could further contribute to prevent these lesions. The objective of the present study was to determine the effect of vitC inclusion (3,600?mg/kg) in high DHA (5?% DW) and α-TOH (3,000?mg/kg) microdiets (diets 5/3,000 and 5/3,000?+?vitC) in comparison to a control diet (1?% DHA DW and 1,500?mg/kg of α-TOH; diet 1/1,500) on sea bass larvae growth, survival, whole body biochemical composition and thiobarbituric acid reactive substances (TBARS) content, muscle morphology, skeletal deformities and antioxidant enzymes, insulin-like growth factors (IGFs) and myosin expression (MyHC). Larvae fed diet 1/1,500 showed the best performance in terms of total length, incidence of muscular lesions and ossification degree. IGFs gene expression was elevated in 5/3,000 diet larvae, suggesting an increased muscle mitogenesis that was confirmed by the increase in the mRNA copies of MyHC. vitC effectively controlled oxidative damages in muscle, increased α-TOH larval contents and reduced TBARS content and the occurrence of skull deformities. The results of the present study showed the antioxidant synergism between vitamins E and C when high contents of DHA are included in sea bass larvae diets.     

Part-by-part dimensional error compensation in compliant sheet metal assembly processes

Dimensional variation in assembly processes is one of the most important issues that affect quality. Although robust design and statistical process quality control help to reduce this problem, they cannot be used for instant variation reduction during assembly operations, especially during process ramp-up. This paper introduces a complete methodology for dimensional-related error compensation in compliant sheet metal assembly processes. The proposed methodology is divided into two steps: (1) an off-line error control-learning module using virtual assembly models to determine necessary adjustments; and (2) an in-line control implementation using a feed-forward control strategy based on the learned adjustments. The off-line learning step focuses on determining control actions or corrections to compensate for the negative effects incoming part errors have on Key Product Characteristics. Specifically, it utilizes a newly developed iterative sampling method based on Kriging fitting to efficiently determine optimal control actions. The in-line feed-forward control identifies appropriate part-by-part adjustments using these learned control actions and incoming assembly component measurements. In this paper, two case studies are presented. First, a mathematical case study presents an empirical proof for the feasibility of the Iterative Sampling and Fitting Algorithm. Second, a simulation-based case study illustrates the effectiveness of the proposed methodology to improve dimensional quality in assembly operations for compliant sheet metal parts.     

A hybrid,auto-adaptive and rule-based multi-agent approach using evolutionary algorithms for improved searching

Selecting the most appropriate heuristic for solving a specific problem is not easy, for many reasons. This article focuses on one of these reasons: traditionally, the solution search process has operated in a given manner regardless of the specific problem being solved, and the process has been the same regardless of the size, complexity and domain of the problem. To cope with this situation, search processes should mould the search into areas of the search space that are meaningful for the problem. This article builds on previous work in the development of a multi-agent paradigm using techniques derived from knowledge discovery (data-mining techniques) on databases of so-far visited solutions. The aim is to improve the search mechanisms, increase computational efficiency and use rules to enrich the formulation of optimization problems, while reducing the search space and catering to realistic problems.     

铅锌尾矿重金属释放影响因素的探讨

铅锌尾矿废渣若不经过处理,会通过风蚀、径流对环境造成重金属污染,对尾矿废渣污染的研究一直是大家关注的方向。多年来,pH被证实是影响重金属释放的重要因素。本文通过实验,研究了浸提方法、pH和盐度对铅锌尾矿废渣重金属元素释放的影响。结果表明,Pb、Zn、Cd、As在pH值呈酸性和碱性时浸出率都较高,Cu、Ni则在pH值为碱性时浸出率更高,盐度对Pb的释放影响效果更为明显。     

Progress towards a methodology for high throughput 3D reconstruction of soot nanoparticles via electron tomography

The aim of this work is to make progress towards the development of 3D reconstruction as a legitimate alternative to traditional 2D characterization of soot. Time constraints are the greatest opposition to its implementation, as currently reconstruction of a single soot particle takes around 5–6 h to complete. As such, the accuracy and detail gains are currently insufficient to challenge 2D characterization of a representative sample (e.g. 200 particles). This work is a consideration of the optimization of the steps included within the computational reconstruction and manual segmentation of soot particles. Our optimal process reduced the time required by over 70% in comparison to a typical procedure, whilst producing models with no appreciable decrease in quality.     

Antioxidant properties,radical scavenging activity and biomolecule protection capacity of flavonoid naringenin and its glycoside naringin: a comparative study

BACKGROUND: This study was designed to evaluate and compare antioxidant capacity and radical scavenging activity of naringin and its aglycone by different in vitro assays. The effects of flavanones on lipid peroxidation, glutathione (GSH) oxidation and DNA cleavage were also assessed. RESULTS: The results showed that naringenin exhibited higher antioxidant capacity and hydroxyl and superoxide radical scavenger efficiency than naringin. Our results evidenced that glycosylation attenuated the efficiency in inhibiting the enzyme xanthine oxidase and the aglycone could act like a more active chelator of metallic ions than the glycoside. Additionally, naringenin showed a greater effectiveness in the protection against oxidative damage to lipids in a dose‐dependent manner. Both flavanones were equally effective in reducing DNA damage. However, they show no protective effect on oxidation of GSH. CONCLUSION: The data obtained support the importance of characterizing the ratio naringin/naringenin in foods when they are evaluated for their health benefits. Copyright © 2010 Society of Chemical Industry     

Fatty Acids and Metabolomic Composition of Follicular Fluid Collected from Environments Associated with Good and Poor Oocyte Competence in Goats

In goats, embryo oocyte competence is affected by follicle size regardless the age of the females. In previous studies we have found differences in blastocyst development between oocytes coming of small (<3 mm) and large follicles (>3 mm) in prepubertal (1–2 months-old) goats. Oocyte competence and Follicular Fluid (FF) composition changes throughout follicle growth. The aim of this study was to analyze Fatty Acids (FAs) composition and metabolomic profiles of FF recovered from small and large follicles of prepubertal goats and follicles of adult goats. FAs were analyzed by chromatography and metabolites by 1H-Nuclear Magnetic Resonance (1H-NMR) Spectrometry. The results showed important differences between adult and prepubertal follicles: (a) the presence of α,β-glucose in adult and no detection in prepubertal; (b) lactate, -N-(CH3)3 groups and inositol were higher in prepubertal (c) the percentage of Linolenic Acid, Total Saturated Fatty Acids and n-3 PUFAs were higher in adults; and (d) the percentage of Linoleic Acid, total MUFAs, PUFAs, n-6 PUFAs and n-6 PUFAs: n-3 PUFAs ratio were higher in prepubertal goats. Not significant differences were found in follicle size of prepubertal goats, despite the differences in oocyte competence for in vitro embryo production.     

Experimental evidence of an upper limit for hydrogen storage at 77 K on activated carbons

An upper limit for hydrogen storage at 77 K on activated carbons was clearly observed in the present experimental work. Such a limit is around 6.4 wt.%, i.e., close to the theoretical limit of 6.8 wt.%. Results of hydrogen storage were obtained in three independent laboratories using volumetric and gravimetric devices. Lab-made activated carbons (ACs) were found to have higher capacities than those of the commercial material AX-21. A maximum excess hydrogen storage capacity of 6.0 wt.% at 77 K and 4 MPa was obtained. This maximum was reduced to 0.6 wt.% at 298 K and 5 MPa. ACs with surface areas (S_BET) as high as 3220 m² g⁻¹ were prepared from chemical activation of anthracites with alkali (Na and K) hydroxides. At 77 K and 4 MPa, excess hydrogen storage capacity was directly correlated with S_BET for ACs having S_BET values lower than 2630 m²/g. Hydrogen uptake at 77 K also correlated with micropore volume and strongly depended on average pore diameter.     

Stability of composite systems with an asymptotically hyperstable subsystem

In this note, it is proved that stability of composite systems including parallel subsystems can be achieved for certain sets of initial conditions and additional stability assumptions for the non-hyperstable subsystems. It is required that at least one subsystem be asymptotically hyperstable.