How to obtain the adhesive strength for double lap joint by using single lap joint

The testing method of adhesive strength of lap joint is prescribed in Japanese Industrial Standard (JIS K6850). However, it has been reported that the strength of double lap joint (DLJ) is about two times larger than the one of single lap joint (SLJ). Therefore, suitable testing method has been required from industries. In this study, the equivalent conditions of strength for SLJ and DLJ are investigated in terms of the intensity of singular stress field (ISSF) appearing at the interface end. First, in order to minimize the bend effect for SLJ, the effect of the specimen geometry on ISSF and deformation angle at the interface corner is considered under the same adhesive geometry and load P. It is found that the minimum ISSF of SLJ can be obtained when the adherend thickness t1 is large enough, and the deformation angle at interface corner is also smallest when adherend thickness t1 is large enough. Therefore, it is necessary to use the specimen with thicker adherend thickness. Then, the equivalent conditions of strength for SLJ and DLJ is investigated by changing adherend thickness. The results show that the strength of the DLJ in JIS (t1=1.5mm) can be obtained by using the SLJ with adherend thickness t1=7mm. When the adherend thickness t1≥25mm, the strength of SLJ is nearly equal to that of DLJ.6th International Conference on Fracture Fatigue and Wear, 26–27 July 2017, Porto, Portuga

Editors’ Notes

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/149556/1/he20319_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/149556/2/he20319.pd

Weight quantification of deposits on hydrogel lenses: A clinical trial

A new method for quantifying of soft contact lens deposits that causes minimal damage to the lens was investigated. Fourteen subjects were fit with Hydrocurve II 55% and Hydrocurve Elite contact lenses. Subjects wore one of each type of lens for three months and lenses were weighed three times (t= 0, 1, 3 months). Lenses were assessed for fitting charicteristics and comfort after each weighing. Six subjects completed the study for three months. Eight of the subjects were dropped from -the study because of decreased lens comfort, torn lenses and contact lens optical problems. Weight data from the six subjects who completed the study were analyzed with one factor repeated measure ANOVA p \u3c 0.05. Hydrocurve II 55% lenses gained a significant amount of weight over the three months while the Hydrocurve Elite did not. We feel that a fifty-seven percent drop-out rate is acceptable for this quantification method. The method (with refinement) has value for future use in contact lens material and solution research

Chromobacterium violaceum as a potential biosurfactant‐producing microorganism

Chromobacterium violaceum is a Gram‐negative bacterium found in the soil and water in tropical and sub‐tropical environments. Its complete genome sequence revealed wide varying alternative pathways for energy generation, complex and extensive systems for stress adaptation, motility and widespread utilization of quorum sensing for control of its inducible systems. Biosurfactants are amphiphilic compounds produced by microorganisms, both intra and extracellularly, that reduce surface and interfacial tensions. In this work, C. violaceum UCP 1552 isolated from the contaminated area of Pernambuco, was used. Biosurfactant production was carried out in 500mL Erlenmeyer flasks containing 250mL of LB medium [tryptone – 10g/L, yeast extract – 5g/L, sodium chloride – 5g/L] plus 5g/L glucose and 1.6g/L soy oil, at 150 rpm and 30°C. Samples were collected at different fermentation times (from 0 to 188h) to evaluate cellular growth, glucose consumption and biosurfactant production (by reduction of surface tension and emulsification index determination). Biomass growth was observed during the first 96h and afterwards the cells entered the stationary phase. Moreover, glucose was consumed in the first 30h. Surface tension of the fermentation broth free of C. violaceum cells recovered after 188h was found to be 32 mN/m. The highest emulsification index was observed for 12h experiment, being 56 and 59% for sunflower oil and nhexadecane, respectively. Results gathered in this study reveal the C. violaceum potential as a biosurfactant‐producer opening novel perspectives for its application in the environmental area.Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES

Crescimento de plântulas de tomate influjenciado por diferentes extratos de vermicomposto.

O presente trabalho teve como objetivo avaliar o crscimento de plantulas de tomate em diferentes concentrações de extratos de vermicomposto extraídas com água e do modo convencional (NaOH).Resumo expandido

O crescimento de plântulas de tomateiro é afetado por extratos de vermicomposto.

O objetivo desse trabalho foi avaliar o efeito de extratos de vermicomposto sobre a morfologia da parte aérea e radicular de plantulas de tomateiro. Observou-se um aumento linear significativo da área foliar (AF) e massa foliar fresca (MFF)

Evaluation antimicrobial and antiadhesive properties of the biosurfactant lunasan produced by candida sphaerica UCP 0995

Different groups of biosurfactants exhibit diverse properties and display a variety of physiological functions in producer microorganisms; these include enhancing the solubility of hydrophobic/water-insoluble compound, heave metal binding, bacterial pathogenesis, cell adhesion and aggregation, quorum sensing and biofilm formation. Candida sphaerica was grown in a low cost medium, consisting of distilled water supplemented with 9% refinery residue of soybean oil and 9% corn steep liquor, for 144 h at 28 C and 150 rpm. The cell-free supernatant obtained at the end of the experiments was submitted to extraction, and afterward the biosurfactant was isolated using methanol with a yield of 9 g l-1. The critical micelle concentration of the biosurfactant was found to be 0.25 mg ml-1 with a surface tension of 25 mN m-1. Several concentrations of the biosurfactant (0.625–10 mg ml-1) were used to evaluate its antimicrobial and antiadhesive activities against a variety of microorganisms. The biosurfactant showed antimicrobial activity against Streptococcus oralis (68%), Candida albicans (57%), and Staphylococcus epidermidis(57.6%) for the highest concentration tested. Furthermore, the biosurfactant at a concentration of 10 mg ml-1 inhibited the adhesion between 80 and 92% of Pseudomonas aeruginosa, Streptococcus agalactiae, Streptococcus sanguis12. Inhibition of adhesion with percentages near 100% occurred for the higher concentrations of biosurfactant used. Results gathered in this study point to a potential use of the biosurfactant in biomedical applicationsThe authors acknowledge the funding agencies FACEPE, CNPq, FINEP, PRONEX, and UNICAMP for using their facilities and CAPES for sandwich doctorate scholarship

Spatial Current Patterns, Dephasing and Current Imaging in Graphene Nanoribbons

Using the non-equilibrium Keldysh Green's function formalism, we investigate the local, non-equilibrium charge transport in graphene nanoribbons (GNRs). In particular, we demonstrate that the spatial current patterns associated with discrete transmission resonances sensitively depend on the GNRs' geometry, size, and aspect ratio, the location and number of leads, and the presence of dephasing. We identify a relation between the spatial form of the current patterns, and the number of degenerate energy states participating in the charge transport. Furthermore, we demonstrate a principle of superposition for the conductance and spatial current patterns in multiple-lead configurations. We demonstrate that scanning tunneling microscopy (STM) can be employed to image spatial current paths in GNR with atomic resolution, providing important insight into the form of local charge transport. Finally, we investigate the effects of dephasing on the spatial current patterns, and show that with decreasing dephasing time, the current patterns evolve smoothly from those of a ballistic quantum network to those of classical resistor network.Comment: 25 pages, 12 figure