Processing and properties of natural fibers reinforced thermoplastic and thermosseting composites

In this work, three different natural fibers were studied and characterized, using optical and SEM microscopy. Woven fabrics of those reinforcement fibers were used to reinforce polyester and epoxy matrices and produce composite plates by vacum lay-up. Also, using an experimental piston blender equipment, long fiber reinforced PLA (LFT) composites were manufactured by hot compression molding. All different obtained composite plates were submitted to mechanical testing in order to determine relevant mechanical proprieties.Fundação para a Ciência e a Tecnologia (FCT

Processing and properties of composites obtained from natural fibres and thermosetting matrices

In this work, different natural fibres were studied and characterized, using optical and SEM microscopy. Those fibres were used to reinforce polyester and epoxy matrices and produce composite plates by hand lay-up. A vacuum bag was then used to allow improving the fibre impregnation, establishing a controlled pressure atmosphere. All different obtained composite plates were submitted to mechanical testing, in order to determine relevant mechanical proprieties. The produced composites were, namely, submitted to flexure and tensile tests, in accordance to ISO 14125 and ISO 527, standards, respectively. It was also determined, for each type of composite, the GIIc property (critical energy release rate in mode II), in order to assess their impact behaviour.Fundação para a Ciência e a Tecnologia (FCT

Mononeuritis multiplex: an uncommon neurological manifestation of cytomegalovirus reactivation in an HIV-infected patient

BACKGROUND: Cytomegalovirus (CMV) reactivation with neurological involvement in patients with acquired immunodeficiency syndrome (AIDS) is increasingly rare since the introduction of antiretroviral therapy (ART). Manifestations include encephalitis, myelitis, polyradiculopathy and, less commonly, mononeuritis multiplex (MNM). We report a case of disseminated CMV disease with gastrointestinal and peripheral and central nervous system involvement in a patient with AIDS, manifesting primarily as MNM. CASE PRESENTATION: A 31-year old woman with AIDS presented with a clinical picture of MNM. Electromyography confirmed the clinical findings. CMV DNA was detected in cerebrospinal fluid (CSF) and blood. Gastrointestinal involvement was histologically documented. HIV RNA was also detected in CSF and brain MRI was consistent with HIV encephalopathy. A diagnosis of disseminated CMV disease (with esophagitis, colitis, encephalitis and MNM) and HIV encephalopathy was made. Treatment consisted of ganciclovir and foscarnet, followed by maintenance therapy with valganciclovir. Evolution was favorable and valganciclovir was stopped after sustained immune recovery following ART initiation. CONCLUSION: We discuss the diagnostic approach to CMV neurological disease, with a focus on MNM and CMV encephalitis. Combination therapy with ganciclovir and foscarnet should be considered for all forms of neurological involvement, although available data are scarce. Since there is significant overlap between CMV encephalitis and HIV encephalopathy, ART drugs with higher CSF penetration may have to be considered. ART and immune recovery are essential to improve outcomes

Assignment of disulphide bridges in Par j 2.0101, a major allergen of Parietaria judaica pollen.

Par j 2.0101, a major allergen of the Parietaria judaica pollen, was expressed in E. coli, purified to homogeneity and fully characterised both at the structural and the functional level. The recombinant rPar j 2.0101 protein showed an allergenic activity in histamine release, skin prick tests and capacity to bind IgE, almost identical to that of the native allergens purified from aqueous pollen extract. The complete pattern of S-S bridges of rPar j 2.0101 was determined by enzymatic digestion with endoproteinase Lys-C followed by mass spectrometric analysis of the resulting peptide mixtures. The eight cysteines occurring in the allergenic protein were found to be paired into the following four disulphides: Cys35-Cys83, Cys45-Cys6O, Cys61-Cys106 and Cys81-Cys121. This structural information probes Par j 2.0101 to attain a 3-D fold consistent with that of the non-specific lipid transfer protein (ns-LTP) family and it represents an effective molecular basis to develop modified antigens by selective site-directed mutagenesis for immunotherapy

Development and assessment to environmentally friendly natural fiber composites

Two different types of natural fibers (jute and sisal) were studied and characterized, using optical microscopy, pycnometry density, single filament and linear density tests. Jute fibers were processed into composite parts from woven fabrics raw-material and sisal fibers were also processed into final composite componentes but in the form of chopped mat. Those fibers were used to reinforce polyester and epoxy matrices and therefore produce composite plates by resin infusion molding. Finally, the final obtained composite plates were submitted to mechanical testing, in order to assess their relevant mechanical properties.Fundação para a Ciência e a Tecnologia (FCT

Asymptotic expansions of the solutions of the Cauchy problem for nonlinear parabolic equations

Let $u$ be a solution of the Cauchy problem for the nonlinear parabolic equation $$\partial_t u=\Delta u+F(x,t,u,\nabla u) \quad in \quad{\bf R}^N\times(0,\infty), \quad u(x,0)=\varphi(x)\quad in \quad{\bf R}^N,$$ and assume that the solution $u$ behaves like the Gauss kernel as $t\to\infty$. In this paper, under suitable assumptions of the reaction term $F$ and the initial function $\varphi$, we establish the method of obtaining higher order asymptotic expansions of the solution $u$ as $t\to\infty$. This paper is a generalization of our previous paper, and our arguments are applicable to the large class of nonlinear parabolic equations

A new hard-particle model for anisotropic fluids

We report a new hard-particle model system consisting of hard cylinders, we have determined the geometrical conditions that let us know whether or not two given cylinders overlap. In addition we have carried out Monte Carlo simulations sampling the canonical ensemble on this system, the numerical results indicate that this system exhibits mesomorphic behaviour

Misdiagnosis of familial Mediterranean fever in patients with Anderson-Fabry disease

Fabry disease (FD) is an underdiagnosed pathology due to its symptomatology that overlaps with various systemic and rheumatic disorders, including familial Mediterranean fever (FMF). We examined the Mediterranean fever (MEFV) and α-galactosidase A (GLA) genes, whose mutations are responsible for FMF and FD, respectively, in 42 unrelated patients diagnosed with FMF, which revealed significant ambiguity regarding some of the symptoms which are also present in FD. The objective of this study was to determine the spectrum of mutations present in these genes, in order to identify cases of mistaken diagnosis of FMF and/or missed diagnosis of FD. Ten out of 42 patients had one mutation in homozygosis or two different mutations in heterozygosis in the MEFV gene; 20/42 had a single heterozygous mutation, and 12/42 did not have genetic alterations in MEFV. The analysis of the GLA gene conducted on all the samples revealed that three subjects, and some members of their families, had two different exonic mutations associated with FD. Family studies allowed us to identify eight other cases of FD, bringing the total undiagnosed subjects to 11/53. Analyzing the MEFV and GLA genes in patients with clinical diagnoses of FMF proved to be fundamentally important for the reduction of diagnostic errors

Molecular and clinical studies in five index cases with novel mutations in the GLA gene

Fabry disease is a metabolic and lysosomal storage disorder caused by the functional defect of the α-galactosidase A enzyme; this defect is due to mutations in the GLA gene, that is composed of seven exons and is located on the long arm of the X-chromosome (Xq21–22). The enzymatic deficit is responsible for the accumulation of glycosphingolipids in lysosomes of different cellular types, mainly in those ones of vascular endothelium. It consequently causes a cellular and microvascular dysfunction. In this paper, we described five novel mutations in the GLA gene, related to absent enzymatic activity and typical manifestations of Fabry disease. We identified three mutations (c.846_847delTC, p.E341X and p.C382X) that lead to the introduction of a stop codon in positions 297, 341 and 382. Moreover we found a missense mutation (p.R227P) in the exon 5 of the GLA gene and a single point mutation (c.639 + 5 G > T) occurring five base pairs beyond the end of the exon 4. These mutations have never been found in our group of healthy control subjects > 2300. The studied patients presented some clinical manifestations, such as cornea verticillata, hypo-anhidrosis, left ventricular hypertrophy, cerebrovascular disorders and renal failure, that, considering the null enzymatic activity, suggest that the new mutations reported here are related to the classic form of Fabry disease. The identification of novel mutations in patients with symptomatology referable to FD increases the molecular knowledge of the GLA gene and it gives clinicians an important support for the proper diagnosis of the disease