Procedural influences on non-linear distortions in welded thin-plate fabrication

Fusion welding is the most common and convenient method used for the fabrication of large, thin-plate welded structures. However, the resulting tendency to out-of-plane distortion exacts severe design and fabrication penalties in terms of poorer buckling performance, lack of fairness in external appearance, poor fit-up and frequent requirements for expensive rework. This study forms part of a long-term project that has the aim of modelling welding and related fabrication processes computationally with particular emphasis on the out-of-plane distortion outcomes. Throughout the present work the computational models have been cross-referenced to realistic experimental test cases. A repeated finding of the trials was that minor variations in fabrication procedures, were found to have significant effects on distortion. In particular, the pre-fabrication procedures, including spot and tack welding, have a significant effect on the initial out-of-plane distortion leading to differences in distortion of the post-welded structures. The support and clamping conditions during welding and cooling of welded thin-plate structures were also found to have a considerable influence on the final predicted out-of-plane distortion. The outcomes often result in different buckling instability behaviour. This paper concentrates on these aspects and draws on studies of buttwelding between plates of thicknesses 3–8 mm.     

Fragility analysis for ballistic design

Effective structural design to resist ballistic effects such as small arms or fragmenting weapons has been a goal since weapons were developed. Approaches currently in use for ballistic design are predominantly deterministic and allow designers to decide what wall thickness should be used to stop a prescribed projectile impacting at a predefined velocity. The research presented in this paper provides a framework for conducting reliability analysis of structures subjected to bullet and fragment demands. Thus, pseudo-fragility curves are developed for the limit states related to spall and perforation of wall panels, residual velocities of bullets and fragments, and injury to personnel. The pseudo-fragility analysis provides engineers and owners with a tool to quickly assess the reliability of a wall system subjected to high velocity, low mass projectiles. In particular, the proposed analysis method allows designers and owners to determine the probability of spall and perforation, residual velocity, and injury as a function of wall thickness or threat standoff distance.

Abbreviations: Cumulative distribution function (CDF): Gives the probability that a stochastic variable ‘X’, with a proper probability density function, is equal to or less than a value (x). Coefficient of variation (COV): The quotient of the standard deviation and the mean     

Fertility-Sparing Approach in Women Affected by Stage I and Low-Grade Endometrial Carcinoma: An Updated Overview

Endometrial cancer (EC) is a deleterious condition which strongly affects a woman’s quality of life. Although aggressive interventions should be considered to treat high-grade EC, a conservative approach should be taken into consideration for women wishing to conceive. In this scenario, we present an overview about the EC fertility-sparing approach state of art. Type I EC at low stage is the only histological type which can be addressed with a fertility-sparing approach. Moreover, no myometrium and/or adnexal invasion should be seen, and lymph-vascular space should not be involved. Regarding the pharmaceutical target, progestins, in particular medroxyprogesterone acetate (MPA) or megestrol acetate (MA), are the most employed agent in conservative treatment of early-stage EC. The metformin usage and hysteroscopic assessment is still under debate, despite promising results. Particularly strict and imperious attention should be given to the follow-up and psychological wellbeing of women, especially because of the double detrimental impairment: both EC and EC-related infertility consequences.     

Influence of substituents in electrochemical and conducting properties of polyaniline derivatives and multi walled carbon nanotubes nanocomposites

Poly(o-methoxyaniline) and poly(o-methylaniline) were synthesized by oxidative polymerization in the presence of multi-walled carbon nanotubes (MWNT) for the fabrication of chloroform processable nanocomposites obtained by embedding MWNT in the polymer matrix without the formation of covalent bonds. The study of pressure-area isotherms highlighted different substituents along the aromatic rings affected the packing grade of macromolecules when spreading on different subphases in relation to the associated sterical hindrance. The presence of MWNT inside the polymer matrix showed to favor a more stretched conformation of macromolecules with a subsequent increment of area/molecule values with respect to the corresponding pure conducting polymers. Furthermore, the sterical hindrance affected the nanocomposite electrochemical properties and conducting polymers containing less hindering substituents along the aromatic rings turned out to be faster electrochemical systems. Less hindering substituents were also able to enhance the conducting properties of nanocomposite materials in association with MWNT.     

Experimental study of dry reforming of biogas in a tubular anode-supported solid oxide fuel cell

The performance of a tubular Ni/YSZ anode supported SOFC directly fed by an anaerobic digestion simulated biogas, with an extra addition of carbon dioxide to operate in conservative operating conditions to avoid coking on the anode support, was investigated. The fuel cell has been tested at a fixed oven temperature of 800 °C and under biogas/CO₂ mixtures with different volumetric ratios, fuel utilization (FU) and current densities. Polarization curves and performance maps were obtained to better understand the influence of the investigated operational parameters on the cell behavior. Furthermore, since the tubular geometry enables an easy separation of the anode and cathode exhaust gases, the anode off-gas has been collected and monitored through a gas-chromatograph under open circuit voltage to investigate on the catalytic behavior of a Ni-based state-of-the-art anode. For corresponding operative conditions, performances of the cell for biogas/CO₂ 1/1.5 (i.e. CH₄/CO₂ 30/70) and 1/2 (i.e. CH₄/CO₂ 24/76) were at least 2% and 4% lower than the case 1/1 (i.e. CH₄/CO₂ 20/80), respectively. The highest efficiency of 43.4% was reached at 17.5 A and FU = 70%.     

Quantitative evaluation of noncovalent interactions between glyphosate and dissolved humic substances by NMR spectroscopy

Interactions of glyphosate (N-phosphonomethylglycine) herbicide (GLY) with soluble fulvic acids (FAs) and humic acids (HAs) at pH 5.2 and 7 were studied by (1)H and (31)P NMR spectroscopy. Increasing concentrations of soluble humic matter determined broadening and chemical shift drifts of proton and phosphorus GLY signals, thereby indicating the occurrence of weak interactions between GLY and humic superstructures. Binding was larger for FAs and pH 5.2 than for HAs and pH 7, thus suggesting formation of hydrogen bonds between GLY carboxyl and phosphonate groups and protonated oxygen functions in humic matter. Changes in relaxation and correlation times of (1)H and (31)P signals and saturation transfer difference NMR experiments confirmed the noncovalent nature of GLY-humic interactions. Diffusion-ordered NMR spectra allowed calculation of the glyphosate fraction bound to humic superstructures and association constants (K(a)) and Gibbs free energies of transfer for GLY-humic complex formation at both pH values. These values showed that noncovalent interactions occurred most effectively with FAs and at pH 5.2. Our findings indicated that glyphosate may spontaneously and significantly bind to soluble humic matter by noncovalent interactions at slightly acidic pH and, thus, potentially pollute natural water bodies by moving through soil profiles in complexes with dissolved humus.     

Comparison of Separations of Fatty Acids from Fish Products Using a 30-m Supelcowax-10 and a 100-m SP-2560 Column

Commercial fish oils and foods containing fish may contain trans and/or isomerized fatty acids (FA) produced during processing or as part of prepared foods. The current American Oil Chemists’ Society (AOCS) official method for marine oils (method Ce 1i-07) is based on separation by use of poly(ethylene glycol) (PEG) columns, for example Supelcowax-10 or equivalent, which do not resolve most unsaturated FA geometric isomers. Highly polar 100-m cyanopropyl siloxane (CPS) columns, for example SP-2560 and CP Sil 88 are recommended for separation of geometric FA isomers. Complementary separations were achieved by use of two different elution temperature programs with the same CPS column. This study is the first direct comparison of the separations achieved by use of 30-m Supelcowax-10 and 100-m SP-2560 columns for fatty acid methyl esters (FAME) prepared from the same fish oil and fish muscle sample. To simplify the identification of the FA in these fish samples, FA were fractionated on the basis of the number and type of double bonds by silver-ion solid-phase extraction (Ag⁺-SPE) before GC analysis. The results showed that a combination of the three GC separations was necessary to resolve and identify most of the unsaturated FA, FA isomers, and other components of fish products, for example phytanic and phytenic acids. Equivalent chain length (ECL) values of most FAME in fish were calculated from the separations achieved by use of both GC columns; the values obtained were shown to be consistent with previously reported values for the Supelcowax-10 column. ECL values were also calculated for the FA separated on the SP-2560 column. The calculated ECL values were equally valid under isothermal and temperature-programmed elution GC conditions, and were valuable for confirmation of the identity of several unsaturated FAME in the fish samples. When analyzing commercially prepared fish foods, deodorized marine oils, or foods fortified with marine oils it is strongly recommended that quantitative data acquired by use of PEG columns is complemented with data obtained from separations using highly polar CPS columns.     

Interspecific Comparison of Constitutive Ash Phloem Phenolic Chemistry Reveals Compounds Unique to Manchurian Ash, a Species Resistant to Emerald Ash Borer

The emerald ash borer (Agrilus planipennis, EAB) is an invasive wood-borer indigenous to Asia and is responsible for widespread ash (Fraxinus spp.) mortality in the U.S. and Canada. Resistance and susceptibility to EAB varies among Fraxinus spp., which is a result of their co-evolutionary history with the pest. We characterized constitutive phenolic profiles and lignin levels in the phloem of green, white, black, blue, European, and Manchurian ash. Phloem was sampled twice during the growing season, coinciding with phenology of early and late instar EAB. We identified 66 metabolites that displayed a pattern of variation, which corresponded strongly with phylogeny. Previously identified lignans and lignan derivatives were confirmed to be unique to Manchurian ash, and may contribute to its high level of resistance to EAB. Other compounds that had been considered unique to Manchurian ash, including hydroxycoumarins and the phenylethanoids calceolarioside A and B, were detected in closely related, but susceptible species, and thus are unlikely to contribute to EAB resistance of Manchurian ash. The distinct phenolic profile of blue ash may contribute to its relatively high resistance to EAB.     

Statistical appraisal of economic design strategies of LV distribution networks

This paper presents a statistical approach for assessing general LV distribution network design strategies based on a large set of realistic test networks and optimal economic circuit design. The test networks are generated using a fractal-based algorithm that allows creation of generic networks with various topological features (e.g., typical of rural/urban/mixed areas) and characterised by different numbers of substations, numbers of customers, load densities, and so forth. In comparison to standards derived from a traditional approach, that is, case studies on a small number of specific real or test networks, the proposed approach facilitates the derivation of more robust conclusions on optimal network design policies and can thus be used as a valuable tool for decision support. The methodology is exemplified through numerical applications for both urban and rural areas.     

Contribution of Compositional Parameters to the Oxidative Stability of Olive and Walnut Oil Blends

Oil blending was conducted to study the effects of changes in fatty acid composition (FAC), tocopherols and total phenol content (TPC) on oxidative stability of virgin olive oil (VOO):walnut oil (WO) blends. The measurement of the antioxidant activity of bioactive components present in the parent oils and blends was achieved by their ability to scavenge the free stable 2,2-diphenyl-1-picrylhydrazyl radical (DPPH·). The highest percentage of DPPH· inhibition was found for pure VOO, and the lowest one for pure WO. EC₅₀ values obtained from the DPPH assay correlated significantly and inversely with TPC. The generation of volatile flavor components in VOO indicated the predominance of C₆ compounds produced through biochemical (enzymatic) pathways, whereas WO showed increased concentrations of medium chain (C₇–C₁₁) aldehydes produced through chemical (oxidative) pathways. The results obtained confirm the importance of VOO phenolics in providing protection against oxidation in VOO and VOO/WO blends. However, considering the impact of FAC and the content of endogenous antioxidant substances mentioned previously on the oxidative stability of the oils analyzed, the effect of an elevated unsaturation level (WO) prevails over a high amount of such bioactive components (VOO).