A numerically efficient finite element hydroelastic analysis

A finite element hydroelastic analysis formulation is developed on the basis of Toupin's complementary variational principle. Emphasis is placed on the special case of an incompressible fluid model which is applicable to propellant tank hydroelastic analysis. A concise fluid inertia representation results from the assumption of incompressibility and the hydroelastic equations reduce to a simplified form associated with the structure alone. The efficiency of the incompressible hydroelastic formulation in unhanced for both fluid and structure by introduction of harmonic reduction as an alternative to Guyan reduction. The theoretical developments are implemented in the NASTRAN Program and the technique is verified and demonstrated as an efficient and accurate approach with a series of illustrative problems including the 1/8 scale space shuttle external tank

Space shuttle pogo studies

Topics covered include: (1) pogo suppression for main propulsion subsystem operation; (2) application of quarter-scale low pressure oxidizer turbopump transfer functions; (3) pogo stability during orbital maneuvering subsystem operation; and (4) errors in frequency response measurements

A numerically efficient finite element hydroelastic analysis. Volume 1: Theory and results

Symmetric finite element matrix formulations for compressible and incompressible hydroelasticity are developed on the basis of Toupin's complementary formulation of classical mechanics. Results of implementation of the new technique in the NASTRAN structural analysis program are presented which demonstrate accuracy and efficiency

Development of technology for fluid-structure interaction modelling of a 1/8-scale dynamic model of the shuttle External Tank (ET). Volume 2: Supporting data appendixes A through C

For abstract, see N75-21359

A numerically efficient finite element hydroelastic analysis. Volume 2: Implementation in NASTRAN, part 2

For abstract, see N76-13529

Sensitivity of Flexibility Monitoring of Offshore Jacket Platforms

Flexibility monitoring is a vibration-based metho

The Cupuacu (Theobroma Grandiflorum) fruit. High performance liquid chromatographic determination of antioxidant phenolic substances in cupuacu seed powder

A method for the qualitative analysis of antioxidant phenolic substances in cupuacu seed powder by high performance liquid chromatography is described. We have used n-exhane to degrease the cupuacu seed powder and a methanol-water (80:20) solution for the extraction of the analytes. HPLC separation was carried out by using a binary gradient elution utilizing methanol-acetonitrile 1:1 (v/v) and 0.5% (w/v) phosphoric acid. Spectral scans were continuously collected in the range 210-370 nm and the spectrophotometric chromatogram was plotted at 280 nm. Spectrofluorimetric detection was carried out with excitation at 280 nm and emission at 330 nm. Epicatechin and quercetin were identified by comparing the chromatographic behaviour and the UV spectrum of the extracted components with those of pure standards, while the spectrofluorimetric detection, by stopped flow technique, has allowed the identification of catechin and has confirmed the spectrophotometric identification of epicatechin

Lubricin is expressed in chondrocytes derived from osteoarthritic cartilage encapsulated in poly (ethylene glycol) diacrylate scaffold

Osteoarthritis (OA) is characterized by degenerative changes within joints that involved quantitative and/or qualitative alterations of cartilage and synovial fluid lubricin, a mucinous glycoprotein secreted by synovial fibroblasts and chondrocytes. Modern therapeutic methods, including tissue-engineering techniques, have been used to treat mechanical damage of the articular cartilage but to date there is no specific and effective treatment. This study aimed at investigating lubricin immunohistochemical expression in cartilage explant from normal and OA patients and in cartilage constructions formed by Poly (ethylene glycol) (PEG) based hydrogels (PEG-DA) encapsulated OA chondrocytes. The expression levels of lubricin were studied by immunohistochemistry: i) in tissue explanted from OA and normal human cartilage; ii) in chondrocytes encapsulated in hydrogel PEGDA from OA and normal human cartilage. Moreover, immunocytochemical and western blot analysis were performed in monolayer cells from OA and normal cartilage. The results showed an increased expression of lubricin in explanted tissue and in monolayer cells from normal cartilage, and a decreased expression of lubricin in OA cartilage. The chondrocytes from OA cartilage after 5 weeks of culture in hydrogels (PEGDA) showed an increased expression of lubricin compared with the control cartilage. The present study demonstrated that OA chondrocytes encapsulated in PEGDA, grown in the scaffold and were able to restore lubricin biosynthesis. Thus our results suggest the possibility of applying autologous cell transplantation in conjunction with scaffold materials for repairing cartilage lesions in patients with OA to reduce at least the progression of the disease

Mir-125a-3p negatively regulates oligodendrocyte precursor cells maturation and is altered in human multiple sclerosis

In the central nervous system, oligodendrocytes provide support to axons thanks to the production of a myelin sheath. During their maturation oligodendroglial precursors (OPCs) follow a very precise differentiation program, finely orchestrated by transcription factors, epigenetic factors and microRNAs, a class of small non-coding RNAs involved in post-transcriptional regulation. Any alterations in this program can potentially contribute to dysregulated myelination, impaired remyelination and neurodegenerative conditions, as it happens in multiple sclerosis. Recently, we identified miR-125a-3p as a new actor of oligodendroglial maturation, that could also be involved in the pathological consequences of multiple sclerosis, showing that its over-expression impairs, whereas its silencing promotes, oligodendrocyte maturation (Lecca et al., Sci Rep, 2016). To shed light on the mechanism underlying this effect, we performed a microarray analysis on OPCs after miR-125a-3p over-expression. This analysis suggested that miR-125a-3p is indeed involved in the regulation of biological processes important for OPC maturation, such as cell-cell interaction and morphological differentiation. To evaluate whether miR-125a-3p modulation may influence the progression of remyelination in vivo, we overexpressed the miR-125a-3p by lentiviral approach in a focal lysolecithin-mediated demyelinating lesion in the subcortical white matter of adult mice. Interestingly, also in this case, we found that miRNA-overexpressing OPCs persisted in an immature (i.e. PDGR\u3b1+/NG2+) state. Moreover, we found that miR-125a-3p levels are altered in both brain active lesions and cerebrospinal fluid of multiple sclerosis patients, suggesting that it could be a potential biomarker of disease. The identification of a new miRNA modulating oligodendrocyte differentiation provides new findings about the complex regulation of myelination processes and we postulate that an antago-miRNA for miR-125a-3p may help promoting oligodendrocyte maturation in diseases characterized by impaired myelin repair. Sponsored by Fondazione Italiana Sclerosi Multipla 2013/R-1 project to MPA and by Fondazione Cariplo, grant n\ub0 2014-1207 to DL

Neuropsychiatric Lupus Erythematosus

Neuropsychiatric involvement in patients with Systemic Lupus Erythematosus (SLE), first mentioned by Kaposi more than 100 years ago, still remains one of the main challenge facing rheumatologist and other physicians. The diagnosis of neuropsychiatric SLE (NPSLE) is complex not only because of the considerable prevalence variation (14-80%) but also because of the wide spectrum of NP manifestations. They vary from overt neurologic alterations (seizure, psychosis), to subtle abnormalities (neurocognitive dysfunctions). Different NP manifestations result from a variety of mechanisms including antibodies, vasculitis, thrombosis, hemorrhages and cytokine-mediated damages. Of note, despite the dramatic clinical manifestations, too often changes at the morphological neuroimaging techniques are minimal and non specific. There is no one diagnostic tool specific for NPSLE and diagnosis must be based on the combinated use of immunoserological tests, functional and anatomical neuroimaging and standardized specific criteria. Symptomatic, immunosuppressive and anticoagulant therapies are the main strategies available in the management of these patients. Therapy for CNS lupus should be adjusted according to the needs of the individual patients. The coming years promise to be an important time for the development of new neuroimaging techniques and for the study of disease mechanism. An early and objective identification of brain involvement will allow for appropriate treatment to avoid severe complications