Fracture modelling of adhesively-bonded joints by an inverse method

Nowadays, any structure must have strength, robustness and lightness, which has increased the industrial interest and research efforts in adhesive joining, mainly in the improvement of strength and fracture properties of adhesives. Thus, in recent years, the use of adhesive joints in industrial applications has gradually grown, replacing some traditional bonding methods, since they have advantages such as reduced stress concentrations, reduced weight and cost, and ease of processing/manufacturing. In this work, the cohesive laws of three adhesives, Araldite AV138, Araldite鮮 2015 and Sikaforce� 7752, were obtained by the application of an inverse adjustment method between the numerical and experimental load-displacement curves (P-?) of Double-Cantilever Beam (DCB) tests for tensile characterization and End-Notched Flexure (ENF) tests for shear characterization. Next, these laws were validated with experimental data of single-lap joints (SLJ) and double-lap joints (DLJ), using Abaqus�. For the Araldite� AV138 and Araldite� 2015, in tension and shear, the triangular law accurately predicted the behaviour of the SLJ and DLJ. For the Sikaforce� 7752, the triangular law did not suitably fit the experimental results. Due to its ductility, the Sikaforce� 7752 could be modelled with a trapezoidal law for improved accuracy

6-Alkyl-3,4-dihydro-2H-pyrans: chemical secretion compounds in neotropical harvestmen

The defensive secretions of five neotropical species of harvestmen (Opiliones: Gonyleptidae) from the Brazilian Atlantic Forest were analyzed and chemically characterized by GC-MS and NMR methods. Three of the species, Cobania picea, Roweria virescens, and Serracutisoma proximum, secrete a mixture of 2,3-dimethyl-1,4-benzoquinone and 2-ethyl-3-methyl-1,4-benzoquinone. The secretions produced by the other two species, Iporangaia pustulosa and Neosadocus maximus, contain 1-hepten-3-one, 5-methyl-1-hexen-3-one, and 1-(6-butyl-3,4-dihydro-2H-pyran-2-yl)pentanone (1) as major components, as well as 2,3-dimethyl-1,4-benzoquinone and 2-ethyl-3-methyl-1,4-benzoquinone as minor constituents. The dihydropyran 1-(6-butyl-3,4-dihydro-2H-pyran-2-yl)pentanone (1) is a new natural product, composed of two 1-hepten-3-one subunits formally linked in a hetero-Diels-Alder reaction. The natural product was proven to be racemic, and its biogenetic origin is discussed.74465866

Chemical imaging of canine oviducts during the post-ovulatory period

It is well known that bitches present a peculiar oocyte maturation, characterized by ovulation of immature oocytes and a long period of viability in the oviduct. Thus, the oviduct in this species plays an essential role in oocyte maturation, in addition to fertilization and early stage embryo development. Different approaches have been used in order to identify the factors involved in each step (from resumption of meiosis through development of embryos) and recently a new technique was used for spatial identification of oviductal proteins in the domestic cat (1). With the purpose to contribute to the understanding of these factors, we applied MALDI imaging mass spectrometry (MALDI-IMS) to obtain protein profiling and imaging of canine oviducts. Reproductive tracts were collected from 4 bitches in estrus (cross-breed, 2 to 6 years old) undergoing routine ovariohysterectomy. Post-ovulatory period was confirmed by blood serum progesterone concentrations (P4 mean\ub1SD: 15.5\ub12.5) and ovarian morphology. The oviducts were carefully dissected, divided into three segments (distal to the ovary-isthmus, proximal to the ovary-infundibulum and the mid-section between the two-ampulla; further confirmed by histology), snap-frozen in liquid nitrogen and stored at -80\ubaC until use. Then, they were sectioned (11 \ub5m) in a cryostat and fixed on ITO (indium tin oxide) conductive glass slides, while serial sections were collected on microscope slides for haematoxylin and eosin staining. For MALDI-IMS, samples were coated with a thin homogeneous layer of CHCA (\u3b1-Cyano-4-hydroxycinnamic acid) matrix using a nebulization device. MALDI images were acquired on an Autoflex III Smartbeam instrument (Bruker Daltonics) with 400 shots/spectrum, over the mass range of m/z 2 to 20 kDa in the positive ion mode. The spatial resolution of images was 80 \ub5m. Mass spectra were characterized by abundant ions of m/z 2279, 2401, 3458 and 4976; which have been tentatively attributed to actin cytoplasmic 2, keratin type 1, neutrophil defensin 1 and thymosin \u3b24, respectively. Actin has been detected in oviduct fluid of alpaca (2) and is related to epithelial cell renewal or secretory activity (3). As previously described in queens (1), defensin, keratin and thymosins are defense proteins that integrate the innate immune systems and are involved in the biological response to cellular damage. These data might contribute to piecing together the puzzle of factors that are involved in the peculiar aspects of the domestic dog reproductive physiology that might hamper in vitro embryo production. 1) Apparicio M, Santos VG, Rocha DFO et al. Matrix-assisted laser desorption/ionization imaging mass spectrometry for the spatial location of feline oviductal proteins. Reprod Domest Anim. 2017;52 (Suppl. 2):88\u201392. (2) Apichela SA, Arga\uf1araz ME, Zampini R et al. Biochemical composition and protein profile of alpaca (Vicugna pacus) oviductal fluid. Anim Reprod Sci. 2015,154:79-85 (3) Steffl M, Schweiger M, Sugiyama T et al. Review of apoptotic and non-apoptotic events in non-ciliated cells of the mammalian oviduct. Ann Anat. 2008,190: 46-52