97 research outputs found
Topological Optimisation of Scaffolds for Tissue Engineering
AbstractAdvanced additive manufacturing technologies, namely Biomanufacturing, are being used to fabricate scaffolds with controlled architecture for tissue engineering applications. These technologies combined with computer-aided design (CAD) enable to produce three-dimensional structures layer-by-layer in a multitude of materials. Actual prediction of the effective mechanical properties of scaffolds produced by Biomanufacturing, is very important for tissue engineering applications. A novel computer based technique for scaffold design is topological optimisation. Topological optimisation is a form of “shape” optimisation, usually referred to as “layout” optimisation. The goal of topological optimisation is to find the best use of material for a body that is subjected to either a single load or a multiple load distribution. This paper proposes a topological optimisation scheme in order to obtain the ideal topological architectures of scaffolds, maximising its mechanical behaviour
Accidental Father-to-Son HIV-1 Transmission During the Seroconversion Period
A 4-year-old child born to an HIV-1 seronegative mother was diagnosed with HIV-1, the main risk factor being transmission from the child's father who was seroconverting at the time of the child's birth. In the context of a forensic investigation, we aimed to identify the source of infection of the child and date of the transmission event. Samples were collected from the father and child at two time points about 4 years after the child's birth. Partial segments of three HIV-1 genes (gag, pol, and env) were sequenced and maximum likelihood (ML) and Bayesian methods were used to determine direction and estimate date of transmission. Neutralizing antibodies were determined using a single cycle assay. Bayesian trees displayed a paraphyletic-monophyletic topology in all three genomic regions, with the father's host label at the root, which is consistent with father-to-son transmission. ML trees found similar topologies in gag and pol and a monophyletic-monophyletic topology in env. Analysis of the time of the most recent common ancestor of each HIV-1 gene population indicated that the child was infected shortly after the father. Consistent with the infection history, both father and son developed broad and potent HIV-specific neutralizing antibody responses. In conclusion, the direction of transmission implicated the father as the source of transmission. Transmission occurred during the seroconversion period when the father was unaware of the infection and was likely accidental. This case shows how genetic, phylogenetic, and serological data can contribute for the forensic investigation of HIV transmission.info:eu-repo/semantics/publishedVersio
Modeling and simulation of photofabrication processes using unsaturated polyester resins
Several kinetic models have been proposed
to simulate thermosetting cure reactions. The most complex
models, based on a mechanistic approach of cure reactions,
are developed based on the concepts of free radical polymerization
and the mechanism of reactions with diffusion.
However, mechanistic models are usually quite impractical
for engineering purposes because of the difficulty in obtaining
the model parameters. An alternative to these mechanistic
models are the phenomenological models, formulated
in terms of the degree of cure and much easier to apply.
Phenomenological models have been largely used to study
thermal-initiated cure reactions, although only few works
used them to model the kinetics of ultraviolet-initiated cure
reaction. This work proposes a photo-thermal-kinetic model
to study the behavior of unsaturated polyester resins during
ultraviolet-initiated cure reactions. The model considers
samples with different amounts of initiator concentration
and cure reactions performed under different ultraviolet
light intensities. The model has been numerically solved
using the finite element techniquePortuguese Foundation for Science and Technology; contract grant number: POCTI/EME/58405/2004
Inhibition of HIV cell-to-cell fusion by antiretroviral drugs and neutralizing antibodies
Poster presented at the 7th iMed.ULisboa Postgraduate Students Meeting. Lisbon, 15 July 2015"Inhibition of HIV cell entry by antiretroviral drugs and neutralizing antibodies (NAbs) is typically measured in assays where cell-free virions enter reporter cell lines. However, direct Env-mediated cell-to-cell transmission is a major mechanism of HIV infection that also needs to be targeted. In this work we aimed to determine the ability of anti-HIV compounds in clinical or research use to inhibit HIV mediated cell-to-cell fusion (syncytia formation)."Fundação para a Ciência e a Tecnologia - Portugal ; European Unio
Towards a Better Understanding of the Factors Associated with Distress in Elderly Cancer Patients: A Systematic Review
his study presents a systematic review of the sociodemographic, clinical, and psychosocial factors associated with distress in elderly cancer patients. Relevant studies were identified using four electronic databases: PubMed, Scopus, Web of Science and ProQuest. Cross-sectional and longitudinal studies exploring factors associated with distress in people over 60 years of age were included and independently assessed using the Joanna Briggs Institute Critical Assessment Checklists. A total of 20 studies met the inclusion criteria. Research showed that being a woman, being single, divorced or widowed, having low income, having an advanced diagnosis, having functional limitations, having comorbidities, and having little social support were factors consistently associated with emotional distress. Data further showed that the impact of age, cancer type, and cancer treatment on symptoms of anxiety and/or depression in elderly patients is not yet well established. The findings of this review suggest that the emotional distress of elderly cancer patients depends on a myriad of factors that are not exclusive, but coexisting determinants of health. Future research is still needed to better understand risk factors for distress in this patient population, providing the resources for healthcare providers to better meet their needs
Hybrid moulds : the use of combined techniques for the rapid manufacturing of injection moulds
"Virtual modeling and rapid manufacturing : advanced research in virtual and rapid prototyping : proceedings of the 2nd International Conference on Advanced Research and Rapid Prototyping, Leiria, Portugal, 28 September - 1 October, 2005 (VR@P 2005)". ISBN 0-415-39062-1Injection moulding is the major polymer processing technique. The mould is a key element of
this process and its characteristics have a key importance on the parts produced. The fabrication of products
with higher added value, especially in terms of production time and costs, is essential for the success of the
mouldmaking industry within a global competitive environment.
This paper presents the concept of hybrid mould, a recent concept for injection moulding of prototype and
short series. Direct and indirect rapid tooling technologies can be used for the fabrication of these moulds.
Hence, new design guidelines need to be defined to produce these moulds as well to assess its performance.
Epoxy tooling and selective laser sintering are the two rapid tooling technologies explored to produce inserts
for hybrid-moulds. This work studies the fabrication of hybrid-moulds through these rapid tooling technologies,
as well its mechanical and thermal behaviour.(undefined
Trends in Mesenchymal Stem Cells\u27 Applications for Skeletal Muscle Repair and Regeneration
Skeletal muscle injuries are quite frequent in traumatic scenarios, such as war injuries or road- or work-related accidents. The skeletal muscle has good regenerative ability, but the extent or recurrence of muscle injury might impair complete structural and functional recovery. Severe tissue loss overwhelms skeletal muscle´s intrinsic regenerative capabilities and culminates in the development of noncontractile fibrous tissue scar. Conservative RICE -based and surgical treatments show limited efficacy in terms of improving these severe cases outcomes, pressing the need for new approaches on skeletal muscle’s therapy. Since the first suggestions of the potential of mesenchymal stem cells for regenerative medicine and tissue engineering, many applications have been explored for a variety of tissues and diseases, including the skeletal muscle, which is the focus of this literature review
Processo de sobremoldação de vedante numa tampa plástica
O objeto da presente patente é o processo de sobremoldação de uma tampa
Plástica com vedante incorporado, na qual é injetado o material de maior dureza sobre o
De menor dureza. Este processo de sobremoldação é aplicado somente em bi-injecção
(utilização de dois materiais ou mais), em tampas plásticas rígidas para embalagens de
Forma redonda ou outras. A solução adotada passou por proteger o vedante (3) do fluxo
(9) do material da tampa (2) de modo a evitar que este cause deformações no vedante (3)
Durante o processo de enchimento. A forma de orientação precisa do fluxo (9) do sobre o
Material de menor dureza (3) evita a deformação deste ultimo recorrendo aos diferenciais
De pressão conjugados com a velocidade. Desta forma é possível injetar sobre um
Material de menor dureza (3), um material de maior dureza (2)
Identification of a mosaic non-inherited small supernumerary ring chromosome 2: cytogenetic-molecular studies and genotype-phenotype correlation
Introduction: The identification of supernumerary marker chromosomes (SMCs) derived from all the autosomes is currently possible, but rarely by conventional cytogenetics alone. Supernumerary ring chromosomes (SRCs) account for about 10% of these cases. SRCs derived from chromosome 2 are unusual, and there are only a few cases reported in the literature. The severity of the phenotype depends on the type of the mosaicism, the percentage of cells affected by the genetic change and the chromosome involved.
Methods: The authors report the case of a boy aged 8 referred for cytogenetic studies, presenting with behavior and learning problems, mental retardation with uncoordenated speech, attention deficit and hyperactivity (PHDA), as well as small slanting palpebral fissures.
The karyotype was obtained from peripheral blood lymphocyte cultures using high resolution GTL banding and standard techniques. Fluorescence in situ hybridization (FISH) was performed using specific probes for the centromeric regions of all chromosomes (Chromoprobe Multiprobe - ISystem).
Results: Cytogenetic analysis revealed two cell lines: one with a supernumerary marker ring chromosome, 47,XY,+r (52%), and a normal cell line, 46,XY (48%). The SRC was identified by FISH with the chromosome 2 centromeric probe. Since the parents had normal karyotypes, this abnormality was “de novo”. Final karyotype of the proband was: mos 47,XY,+r[26]/46,XY[24].ish r(2)(D2Z2+)dn.
Discussion: The clinical description of this patient is in agreement with other reports of the literature. Molecular characterization by FISH analyses is an useful way of investigating the presence of euchromatin contained in a SMC and establishing new chromosomal syndromes. However, to better characterize this ring, in order to establish a more accurate genotype-phenotype correlation, more studies involving other technologies should be performed, thus allowing suitable genetic counsellin
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