Light layer honeycomb panels could replace traditional wood materials, if their stiffness and strength properties could be improved. The aim of this research was to design and determine elastic properties of sandwich panels (SPs) based on a dual corrugated HDF core. Stiffness matrix values of elements were determined by a numerical method. The 3D calculation results were compared with those of the homogeneous model. The calculation results were collated with those of experimental investigations. It was demonstrated that the linear elasticity modulus as well as the modulus of rupture of the SPs were comparable with mechanical properties of a particle board with identical thickness, while the SP has a 1/3 lower density. The panel core exhibited significant orthotropic properties. In the xy plane it could be characterized as an auxetic structure. The homogeneous model leads to results similar to those achieved from the 3D model and observed in experimental tests.
Purpose of reviewWe aim to illustrate the potential viability of MCTD as an underlying aetiology of Melkersson–Rosenthal syndrome. The case is probably the first description available in the literature of the Melkersson–Rosenthal as an early manifestation of mixed connective tissue disease.Recent findingsThe Melkersson–Rosenthal syndrome consists of a triad of recurrent lip and/or face swelling, fissured tongue, and intermittent facial palsy. Mixed connective tissue disease is a multisystemic disorder with overlapping features of systemic lupus erythematosus, scleroderma, and polymyositis, and is differentiated from them by a high titer of antibodies to ribonucleoprotein. The paper presents a case report of Melkersson–Rosenthal syndrome with an onset in childhood that derived from vasculitis that turned out to be an early manifestation of mixed connective tissue disease. We used MRI to evaluate patient’s brain structure and Immunoblot Ena Profil 1 test to test serum autoantibodies level. The patient has a typical for Melkersson–Rosenthal syndrome triad of symptoms: bilateral facial nerve palsy, lingua plicata and facial oedema. Both TC and MRI of the head show no changes as well as laboratory tests except Anti-SS-A (Anti-Ro) and Anti-RNP autoantibody serum level that was highly positive.SummaryNeurological involvement of the MCTD usually includes, according to the frequency of the occurrence, trigeminal neuralgia, headaches, sensorineural hearing, cerebral haemorrhage, transverse myelitis, cauda equina syndrome, retinal vasculitis, progressive multifocal encephalopathy, and demyelinating neuropathy. For clinical practice it is important to remember that Melkersson–Rosenthal syndrome can also be the neurological manifestation of MCTD, especially when accompanied by other systemic symptoms.
The problem of optimal design of the statically indeterminate arch girder which constitutes the primary structural system of the arch bridge is presented. The task is to determine the optimal shape of the axis of the arch girder, as well as the optimal distribution of the cross section height, ensuring the minimum arch volume as well as fulfillment of the standard requirements. This optimisation task, with numerous control functions and constraints, is formulated as a control theory problem with maintaining the formal structure of the minimum principle and then transformed to the multipoint boundary value problem and solved by means of numerical methods. The numerical results are obtained with optimal control methods, using the Dircol software. Since the changes in the shape and cross-section of the arch affect the distribution of the dead and moving loads transferred on the girder from the bridge deck, the optimisation procedure is combined with the finite element method analysis, which together with the complexity of the multidecision arch optimisation problem accounts for the novelty of the proposed approach. The numerical analysis reveals that the optimal girder shape is the frame-arched structure, with considerable lengths of straight sections and only short arch elements, in the areas of the application of concentrated forces and moments. The presented method can be successfully extended to optimisation of structures with different static schemes and load categories taken into account.
Fifteen (soil and intestinal) strains of Desulfovibrio desulfuricans species were typed by PCR method with the use of primers specific for repetitive extragenic palindromic (REP) and enterobacterial repetitive intergenic consensus (ERIC) sequences. As a result, characteristic DNA fingerprints for the strains were obtained. Moreover, the genetic profiles were found to be useful for typing and distinguishing the strains of D. desulfuricans. According to cluster analysis, PCR with primers complementary to the sequences REP appeared to be slightly more discriminatory than PCR with ERIC primers for the investigated strains. Distinct fingerprint patterns of two isolates derived from the same patient pointed to the different origin of both strains.
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