Study on stability and free vibration behavior of porous FGM beams

International audienceIn this paper, buckling and free vibration of imperfect, functionally graded beams, including porosities, are investigated, using a higher order shear strain theory. Due to defects during the manufacturing process, micro porosities may appear in the material, hence the appearance of this imperfection in the structure. The material properties of the beams are assumed to vary regularly, with power and sigmoid law, in the direction of thickness. A novel porosity distribution affecting the functionally graded volume fraction is presented. For the compact formulation used for cementite-based materials and already used in P-FGM, we have adapted it for the distribution of S-FGM. The equations of motion in the FG beam are derived using Hamilton's principle. The boundary conditions for beam FG are assumed to be simply supported. Navier's solution is used to obtain the closed form solutions of the FG beam. The numerical results of this work are compared with those of other published research to verify accuracy and reliability. The comparisons of different shear shape functions, the influence of porosity, thickness and inhomogeneity parameters on buckling and free vibration of the FG beam are all discussed. It is established that the present work is more precise than certain theories developed previously. Copyright © 2022 Techno-Press, Ltd

Histological analysis of indirect somatic embryogenesis in the Marsh clubmoss Lycopodiella inundata (L.) Holub (Pteridophytes)

An efficient in vitro plant regeneration method was developed for Lycopodiella inundata (L.) Holub, an endangered medicinal Lycopod (Pteridophytes). Vegetative apices were used as explant material. Nodular calluses were established after three cycles (13 weeks each) on a medium containing a few minerals and organic compounds and supplemented with 0.05 piM 3-indolebutyric acid (IBA) and 1.4 ~iM kinetin (Kin). Propagation was achieved every 13 weeks on this callus medium (CM). When nodular calluses were transferred on a medium supplemented with 2.5 pM IBA and 0.33 ptM gibberellic acid (GA3) designated as embryogenic medium (EM), organized structures appeared and developed into plantlets. Development phases were characterized by histological studies. Some phases of zygotic embryogenesis previously described for Lycopods were observed in L. inundata. Histological analyses established that an indirect somatic embryo was derived from a single embryogenic cell by following the zygotic developmental pathway. As this phenomenon has not previously been reported in Lycopods, a comparison between somatic and zygotic embryos is discussed based upon morphology and histology. (Résumé d'auteur

Buckling of Generic Higher-Order Shear Beam/Columns with Elastic Connections: Local and Nonlocal Formulation

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Cold pressed Pinus halepensis Mill. seed oil for potential health applications: Analgesic, anti-inflammatory effects, and assessment of inflammatory mediators by RT-qPCR in skin wound healing

Ethnopharmacological relevance: Pinus halepensis Mill. seed (Pinaceae), commonly known as Zgougou, is widely consumed in the Mediterranean region and has long been used to treat diseases including bronchitis, rheumatism, infection, and inflammation.Aim of the study: The present study was focused on the investigation of some pharmacological activities, such as analgesic, anti-inflammatory, and wound healing effects, of cold-pressed oil of Pinus halepensis Mill. seed (COPHS).Materials and methods: The fixed oil of Pinus halepensis seed was extracted by a cold pressing process. The analgesic activity of COPHS was examined by acetic acid and formalin-induced contortion and pain tests. The anti-inflammatory effects were evaluated in carrageenan and formalin induced paw and ear edema models. Wound healing potential was assessed on an experimental skin wound, and the expression levels of inflammation mediators were determined by RT-qPCR in skin wound healing. Results: The results showed analgesic efficacy through significant inhibition of abdominal cramps (59.15%) and pain (75.91%). In addition, this oil exerted an anti-inflammatory effect by inhibiting ear (62.25%) and paw (70.00%) edema. The COPHS stimulated wound contraction in experimental skin wound healing with a contraction rate of 89.23% with notable reduction of TNF-alpha and NF-kB expression levels in the treated groups. Conclusions: This study provided for the first time the pharmacological profile, particularly the analgesic, antiinflammatory, and healing effects, of fixed oil extracted by cold pressing from the seed of Pinus halepensis Mill