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1.
Heliyon ; 10(3): e25415, 2024 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-38356493

RESUMO

Despite the numerous concepts of caregiving discussed in the literature, there is still no agreed definition and concept of family caregiving from the perspective of Islam. This study aims to comprehensively define family caregiving from Islamic religious and Muslim cultural perspectives. Rodger's evolutionary model was used to generate content by analyzing and redefining concepts. A thorough examination of the relevant literature using Scopus, PubMed, Medline, and CINAHL databases also trusted sources offered a total of 52 articles and 8 books to be reviewed. Our study reveals that family caregiving is viewed as God's gift as important as an essential religious and cultural obligation in Islam, where humans are expected to deliver care for their families although they are unprepared. This can be motivated by aspirations for respect, love, responsibility, and a desire to recompense parents, as well as the belief that by doing so they will be rewarded in the hereafter. The provision of family caregiving leads to positive consequences such as living with hope, gaining rewards and achievement, but at the same time, it also causes devastated life. This research contributes to a new discourse on family caregiving based on Islamic literature which helps in the comprehension of the practices of Muslim communities worldwide.

2.
Sci Data ; 10(1): 136, 2023 03 15.
Artigo em Inglês | MEDLINE | ID: mdl-36922515

RESUMO

The Ocean Carbon and Acidification Data System (OCADS) is a data management system at the National Oceanic and Atmospheric Administration (NOAA) National Centers for Environmental Information (NCEI). It manages a wide range of ocean carbon and acidification data, including chemical, physical, and biological observations collected from research vessels, ships of opportunity, and uncrewed platforms, as well as laboratory experiment results, and model outputs. Additionally, OCADS serves as a repository for related Global Ocean Observing System (GOOS) biogeochemistry Essential Ocean Variables (EOVs), e.g., oxygen, nutrients, transient tracers, and stable isotopes. OCADS endeavors to be one of the world's leading providers of ocean carbon and acidification data, information, products, and services. To provide the best data management services to the ocean carbon and acidification research community, OCADS prioritizes adopting a customer-centric approach and gathering knowledge and expertise from the research community to improve its data management practices. OCADS aims to make all ocean carbon and acidification data accessible via a single portal, and welcomes submissions from around the world: https://www.ncei.noaa.gov/products/ocean-carbon-acidification-data-system/.

3.
Ann Clin Biochem ; 58(4): 318-326, 2021 07.
Artigo em Inglês | MEDLINE | ID: mdl-33591793

RESUMO

INTRODUCTION: Specific patterns of blood test results are associated with COVID-19 infection. The aim of this study was to identify which blood tests could be used to assist in diagnosing COVID-19. METHOD: A retrospective review was performed on consecutive patients referred to hospital with a clinical suspicion of COVID-19 over a period of four weeks. The patient's clinical presentation and severe acute respiratory syndrome coronavirus 2 reverse-transcription polymerase chain reaction (SARS-CoV-2 RT-PCR) were recorded. The patients were divided by diagnosis into COVID (COVID-19 infection) or CONTROL (an alternate diagnosis). A retrospective review of consecutive patients over a further two-week period was used for the purposes of validation. RESULTS: Overall, 399 patients (53% COVID, 47% CONTROL) were analysed. White cell count, neutrophils and lymphocytes were significantly lower, while lactate dehydrogenase and ferritin were significantly higher, in the COVID group in comparison to CONTROL. Combining the white cell count, lymphocytes and ferritin results into a COVID Combined Blood Test (CCBT) had an area under the curve of 0.79. Using a threshold CCBT of -0.8 resulted in a sensitivity of 0.85 and a specificity of 0.63. Analysing this against a further retrospective review of 181 suspected COVID-19 patients, using the same CCBT threshold, resulted in a sensitivity of 0.73 and a specificity of 0.75. The sensitivity was comparable to the SARS-CoV-2 RT PCR. DISCUSSION: Mathematically combining the blood tests has the potential to assist clinical acumen allowing for rapid streaming and more accurate patient flow pending definitive diagnosis. This may be of particular use in low-resource settings.


Assuntos
Teste de Ácido Nucleico para COVID-19 , COVID-19 , Ferritinas/sangue , L-Lactato Desidrogenase/sangue , Reação em Cadeia da Polimerase Via Transcriptase Reversa , SARS-CoV-2 , Idoso , Idoso de 80 Anos ou mais , COVID-19/sangue , COVID-19/diagnóstico , Feminino , Humanos , Contagem de Leucócitos , Masculino , Pessoa de Meia-Idade , Estudos Retrospectivos
4.
Perspect Public Health ; 139(3): 137-146, 2019 May.
Artigo em Inglês | MEDLINE | ID: mdl-30950682

RESUMO

INTRODUCTION: Research over the last decade has identified both strengths and limitations in the use of routinely prescribed psychological therapies for depression. More recently, a focus on how creative art therapies and 'arts on prescription' are developing a growing recognition of their potential additional therapeutic mechanisms for depression. AIM: In an attempt to develop a new therapeutic intervention for depression, this research aligned both the evidence base surrounding the arts on prescription movement, collating these with client-reported helpful factors and preferences for therapeutic interventions. METHODS: We developed a framework for a new pluralistic 'meta-approach' of therapy for depression, based on; an interdisciplinary thematic synthesis of active ingredients, considered specific features implemented in therapy, and client-reported helpful factors considered to be the broad features or experiences in therapy from both talking therapies and creative approaches. This framework contributed to the development of a pilot workshop entitled Arts for the Blues - A New Creative Psychological Therapy for Depression. An outline of, and evaluation from this workshop is presented in this article. Workshop participants were recruited via a voluntary workshop taking place at a North West Higher Education Institution Arts and Health conference ( N = 15). RESULTS: The workshop was evaluated using quantitative measures, with results indicating around a 70% overall satisfaction, followed up with qualitative commentary around areas of good practice and areas for development. These included the positive reflection on the application of creative arts and the multimodal nature of the approach, while others reflected on the potential overwhelming nature of utilising multimodal methods for individuals with depression. CONCLUSION: Overall feedback from the pilot workshop is discussed in relation to prior research, giving credence to the potential for incorporating arts into therapy.


Assuntos
Arteterapia , Depressão/terapia , Humanos , Satisfação do Paciente , Projetos Piloto , Avaliação de Programas e Projetos de Saúde
5.
Leukemia ; 31(1): 51-57, 2017 01.
Artigo em Inglês | MEDLINE | ID: mdl-27461063

RESUMO

TCF3-PBX1 (E2A-PBX1) is a recurrent gene fusion in B-cell precursor acute lymphoblastic leukemia (BCP-ALL), which is caused by the translocation t(1;19)(q23;p13). TCF3-PBX1 BCP-ALL patients typically benefit from chemotherapy; however, many relapse and subsequently develop resistant disease with few effective treatment options. Mechanisms driving disease progression and therapy resistance have not been studied in TCF3-PBX1 BCP-ALL. Here, we aimed to identify novel treatment options for TCF3-PBX1 BCP-ALL by profiling leukemia cells from a relapsed patient, and determine molecular mechanisms underlying disease pathogenesis and progression. By drug-sensitivity testing of leukemic blasts from the index patient, control samples and TCF3-PBX1 positive and negative BCP-ALL cell lines, we identified the phosphatidylinositide 3-kinase delta (p110δ) inhibitor idelalisib as an effective treatment for TCF3-PBX1 BCP-ALL. This was further supported by evidence showing TCF3-PBX1 directly regulates expression of PIK3CD, the gene encoding p110δ. Other somatic mutations to TP53 and MTOR, as well as aberrant expression of CXCR4, may influence additional drug sensitivities specific to the index patient and accompanied progression of the disease. Our results suggest that idelalisib is a promising treatment option for patients with TCF3-PBX1 BCP-ALL, whereas other drugs could be useful depending on the genetic context of individual patients.


Assuntos
Proteínas de Fusão Oncogênica , Leucemia-Linfoma Linfoblástico de Células Precursoras/tratamento farmacológico , Leucemia-Linfoma Linfoblástico de Células Precursoras/patologia , Purinas/farmacologia , Quinazolinonas/farmacologia , Adulto , Linhagem Celular Tumoral , Classe Ia de Fosfatidilinositol 3-Quinase/genética , Progressão da Doença , Regulação Neoplásica da Expressão Gênica , Humanos , Masculino , Proteínas de Fusão Oncogênica/fisiologia , Inibidores de Fosfoinositídeo-3 Quinase , Leucemia-Linfoma Linfoblástico de Células Precursoras/genética , Purinas/uso terapêutico , Quinazolinonas/uso terapêutico , Recidiva
6.
Leukemia ; 31(2): 301-309, 2017 02.
Artigo em Inglês | MEDLINE | ID: mdl-27499136

RESUMO

Inhibitors of B-cell lymphoma-2 (BCL-2) such as venetoclax (ABT-199) and navitoclax (ABT-263) are clinically explored in several cancer types, including acute myeloid leukemia (AML), to selectively induce apoptosis in cancer cells. To identify robust biomarkers for BCL-2 inhibitor sensitivity, we evaluated the ex vivo sensitivity of fresh leukemic cells from 73 diagnosed and relapsed/refractory AML patients, and then comprehensively assessed whether the responses correlated to specific mutations or gene expression signatures. Compared with samples from healthy donor controls (nonsensitive) and chronic lymphocytic leukemia (CLL) patients (highly sensitive), AML samples exhibited variable responses to BCL-2 inhibition. Strongest CLL-like responses were observed in 15% of the AML patient samples, whereas 32% were resistant, and the remaining exhibited intermediate responses to venetoclax. BCL-2 inhibitor sensitivity was associated with genetic aberrations in chromatin modifiers, WT1 and IDH1/IDH2. A striking selective overexpression of specific HOXA and HOXB gene transcripts were detected in highly BCL-2 inhibitor sensitive samples. Ex vivo responses to venetoclax showed significant inverse correlation to ß2-microglobulin expression and to a lesser degree to BCL-XL and BAX expression. As new therapy options for AML are urgently needed, the specific HOX gene expression pattern can potentially be used as a biomarker to identify venetoclax-sensitive AML patients for clinical trials.


Assuntos
Antineoplásicos/farmacologia , Regulação Leucêmica da Expressão Gênica , Genes Homeobox , Leucemia Mieloide Aguda/genética , Proteínas Proto-Oncogênicas c-bcl-2/antagonistas & inibidores , Compostos de Anilina/farmacologia , Antineoplásicos/uso terapêutico , Biópsia , Medula Óssea/patologia , Compostos Bicíclicos Heterocíclicos com Pontes/farmacologia , Estudos de Casos e Controles , Linhagem Celular Tumoral , Análise por Conglomerados , Resistencia a Medicamentos Antineoplásicos/genética , Exoma , Perfilação da Expressão Gênica , Sequenciamento de Nucleotídeos em Larga Escala , Humanos , Isocitrato Desidrogenase/genética , Leucemia Mieloide Aguda/diagnóstico , Leucemia Mieloide Aguda/tratamento farmacológico , Família Multigênica , Mutação , Sulfonamidas/farmacologia , Proteínas WT1/genética , Microglobulina beta-2/genética
7.
Mar Pollut Bull ; 105(1): 110-9, 2016 Apr 15.
Artigo em Inglês | MEDLINE | ID: mdl-26947926

RESUMO

Among the discoveries of the Deepwater Horizon blowout was the so-called "sub-surface plume"; herein termed the "oil-trapping layer". Hydrocarbons were found positioned at ~1100-1300m with thickness ~100-150m and moving horizontally to the SW in a vertically stratified layer at the junction of the cold abyssal water and the permanent thermocline. This study focuses on its formation process and fate of the hydrocarbons within. The originality of this work to the field is two-fold, first it provides a conceptual framework which places layer origin in the context of a horizontal "intrusion" from the near-field, vertical, blow-out plume and second, it offers a theoretical model for the hydrocarbon chemicals within the horizontal layer as it moves far-afield. The model quantifies the oil-material fractionation process for the soluble and fine particle. The classical Box model, retrofitted with an internal gradient, the "G-Box", allows an approach that includes turbulent eddy diffusion coupled with droplet rise velocity and reactive decay to produce a simple, explicit, transparent, algebraic model with few parameters for the fate of the individual fractions. Computations show the soluble and smallest liquid droplets moving very slowly vertically through the layer appearing within the trapping layer at low concentration with high persistence. The larger droplets move-through this trapping zone quickly, attain high concentrations, and eventually form the sea surface slick. It impacts the field of oil spill engineering science by providing the conceptual idea and the algorithms for projecting the quantities and fractions of oil-material in a deep water, horizontal marine current being dispersed and moving far afield. In the field of oil spill modeling this work extends the current generation near-field plume source models to the far-field. The theory portrays the layer as an efficient oil-material trap. The model-forecasted concentration profiles for alkanes and aromatics against the available field data support the proposed theory and the resulting model.


Assuntos
Hidrocarbonetos/análise , Modelos Químicos , Poluição por Petróleo/análise , Petróleo/análise , Poluentes Químicos da Água/análise , Fracionamento Químico , Monitoramento Ambiental , Golfo do México
8.
J Mech Behav Biomed Mater ; 57: 334-46, 2016 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-26875147

RESUMO

Metallic bone plates are commonly used for arm bone fractures where conservative treatment (casts) cannot provide adequate support and compression at the fracture site. These plates, made of stainless steel or titanium alloys, tend to shield stress transfer at the fracture site and delay the bone healing rate. This study investigates the feasibility of adopting advanced composite materials to overcome stress shielding effects by optimising the geometry and mechanical properties of the plate to match more closely to the bone. An ulnar transverse fracture is characterised and finite element techniques are employed to investigate the feasibility of a composite-plated fractured bone construct over a stainless steel equivalent. Numerical models of intact and fractured bones are analysed and the mechanical behaviour is found to agree with experimental data. The mechanical properties are tailored to produce an optimised composite plate, offering a 25% reduction in length and a 70% reduction in mass. The optimised design may help to reduce stress shielding and increase bone healing rates.


Assuntos
Placas Ósseas , Teste de Materiais , Fenômenos Mecânicos , Fraturas da Ulna/cirurgia , Adulto , Materiais Biocompatíveis/química , Parafusos Ósseos , Análise de Elementos Finitos , Vidro/química , Humanos , Masculino
10.
Foot Ankle Surg ; 21(2): 97-102, 2015 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-25937408

RESUMO

BACKGROUND: Arthroscopic arthrodesis is an accepted technique for the ankle but less commonly reported for multiple hindfoot joints. We present a case series review to establish the feasibility of this surgery. METHODS: In a consecutive series of 112 arthroscopic hindfoot arthrodeses, 18 involved decortication and fusion of 2 or 3 hindfoot joints. These were reviewed to identify complications, union rates and improvement over preoperative state. RESULTS: Mean age was 62 (45-78). Mean follow-up was 4.4 (1.75-7.5) years. There were no perioperative complications. The four patients with triple fusions united with good or excellent outcomes. Of 14 patients with subtalar and talonavicular arthrodeses there were three talonavicular non-unions. CONCLUSIONS: Arthroscopic double and triple arthrodeses appear feasible salvage options for pain and deformity. Decortication of all three joints and rotatory correction of deformity is possible whilst preserving the soft tissue envelope. Late adjacent joint pain and arthrosis can occur.


Assuntos
Artrite/cirurgia , Artrodese/métodos , Articulações do Pé/cirurgia , Idoso , Artroscopia , Estudos de Viabilidade , Feminino , Humanos , Masculino , Pessoa de Meia-Idade
12.
J Mech Behav Biomed Mater ; 28: 1-14, 2013 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-23959231

RESUMO

Completely resorbable composites are an attractive alternative for metallic bone-fracture fixation devices. However, failure of their interfacial integrity within aqueous environments, which can lead to a rapid loss of overall mechanical properties, has been reported in the literature. In this study coupling agents were investigated for phosphate glass fibre reinforced poly(lactic acid) composites. Three coupling agents with varying wettability were employed to improve initial mechanical properties and their retention in vitro via improvement of the interfacial bond between polymer matrix and fibres. Coupling agents were grafted onto the glass fibres by dip-coating in coupling agent solution at optimised concentrations. Three-aminopropyltriethoxy silane and sorbitol ended PLA oligomer treatments improved the initial flexural properties (27% strength with APS and 17% modulus via SPLA treatment) of the composites and 3-aminopropyltriethoxy silane and hexamethylene diisocyanate (HDI) treatments also decreased the loss of flexural strength and modulus during degradation. HDI treated samples retained 57.2% and 64.7% of their initial strength and modulus, respectively compared to control where only 34% of initial strength and 52% of initial modulus was retained after 28 days of degradation in PBS solution. Initial improvements in flexural properties were associated with improved shear bond strength at the interface due to covalent bonding between the glass fibres and polymer matrix provided by the coupling agents. Delay in mechanical property loss with degradation was suggested to be due to the hydrophobicity at the interface, which could have hindered the interfacial integrity loss and consequently loss of mechanical integrity of the composites. All coupling agent treated and control composites were tested for cytocompatibility using a primary human osteoblast cell line. A comparable response to the control, in terms of cell adhesion, proliferation and differentiation was observed supporting the use of these agents within implantable devices.


Assuntos
Materiais Biocompatíveis/química , Materiais Biocompatíveis/farmacologia , Vidro/química , Ácido Láctico/química , Fenômenos Mecânicos , Fosfatos/química , Polímeros/química , Fosfatase Alcalina/metabolismo , Proliferação de Células/efeitos dos fármacos , Colágeno/biossíntese , Colágeno/metabolismo , Humanos , Osteoblastos/citologia , Osteoblastos/efeitos dos fármacos , Osteoblastos/metabolismo , Osteocalcina/metabolismo , Poliésteres , Água/química
13.
J Biomed Mater Res A ; 101(11): 3301-10, 2013 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-23983190

RESUMO

Fully resorbable phosphate glass fiber reinforced polymer composites have shown real potential for replacing some of the existing metallic bone fracture fixation devices. However, some of these composites have not provided suitable mechanical strength profiles over the required healing period for bone. Typically, it has been seen that these composites can lose up to 50% or more of their strength within the first week of degradation. Functionalizing the glass surface to promote polymer adhesion or to introduce hydrophobicity at the glass surface could potentially introduce control over the mechanical properties of the composite and their retention. In this study eight chemical agents namely, Glycerol 2-phosphate disodium salt; 3-phosphonopropionic acid; 3-aminopropyltriethoxy silane; etidronic acid; hexamethylene diisocyanate; sorbitol/sodium ended PLA oligomers and amino phosphonic acid, were selected to functionalise the bulk phosphate glass surface. Selected chemical agents had one functional group (-OH or O C N) to react with the glass and another functionality (either -OH, NH2, or Na) to react with the polymer matrix and/or produce hydrophobicity at the fiber surface. Bulk phosphate glass surface-treated with the above agents were assessed for the cytotoxicity of degradation products cell-material interaction in short- and long-term direct cytocompatibility studies. Results obtained from these cytocompatibility studies (using human osteosarcoma (MG63) and primary human osteoblast cell lines) revealed no cytotoxicity from the degradation products and a response comparable to controls in terms of cell functions (attachment, viability, metabolic activity, proliferation, and differentiation) and morphology.


Assuntos
Vidro/química , Teste de Materiais , Fosfatos/química , Fosfatos/farmacologia , Poliésteres/química , Adesividade/efeitos dos fármacos , Fosfatase Alcalina/metabolismo , Linhagem Celular , Proliferação de Células/efeitos dos fármacos , Forma Celular/efeitos dos fármacos , Sobrevivência Celular/efeitos dos fármacos , Colágeno/biossíntese , DNA/metabolismo , Humanos , Osteoblastos/citologia , Osteoblastos/efeitos dos fármacos , Osteoblastos/enzimologia , Osteoblastos/ultraestrutura , Osteocalcina/metabolismo
14.
Sci Total Environ ; 465: 205-15, 2013 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-23465429

RESUMO

Elucidation of the drivers of soil carbon (C) change is required to enable decisions to be made on how to achieve soil C sequestration. Interactions between different components in the ecosystem in combination with feedback mechanisms mean that identifying drivers through conventional experimental approaches or by retro-fitting models to data are unlikely to result in the insights needed for the future. This paper explains soil C dynamics by using a process-based model. Drivers considered in the model include nitrogen (N) fertiliser inputs, intake demand, and off-take of animal products. The effect of the grazing animal in uncoupling the C and N cycles is explained, plus the implications of the farming system ('drystock' versus milk). The model enables depiction of the dynamic equilibrium achieved with time when a proposed change in the drivers is sustained. The results show that soil C loss under lactating cows is a result of N, rather than C, being removed in milk. Counter-intuitively, at the same intake demand, N loss under 'milk' is less than under 'dry-stock', as is C loss in animal respiration. Possibilities for changing the longevity of C in the soil are discussed, and the compromise between food production, N loss and C sequestration is considered.

15.
Mater Sci Eng C Mater Biol Appl ; 33(4): 1914-24, 2013 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-23498213

RESUMO

Fibre reinforced composites have recently received much attention as potential bone fracture fixation applications. Bioresorbable composites based on poly lactic acid (PLA) and phosphate based glass fibre were investigated according to ion release, degradation, biocompatibility and mechanical retention profiles. The phosphate based glass fibres used in this study had the composition of 40P2O5-24MgO-16CaO-16Na2O-4Fe2O3 in mol% (P40). The degradation and ion release profiles for the composites showed similar trends with the amount of sodium and orthophosphate ions released being greater than the other cations and anions investigated. This was attributed to low Dietzal's field strength for the Na(+) in comparison with Mg(2+) and Ca(2+) and breakdown of longer chain polyphosphates into orthophosphate ions. P40 composites exhibited good biocompatibility to human mesenchymal stem cells (MSCs), which was suggested to be due to the low degradation rate of P40 fibres. After 63 days immersion in PBS at 37 °C, the P40 composite rods lost ~1.1% of mass. The wet flexural, shear and compressive strengths for P40 UD rods were ~70%, ~80% and ~50% of their initial dry values after 3 days of degradation, whereas the flexural modulus, shear and compressive strengths were ~70%, ~80%, and ~65% respectively. Subsequently, the mechanical properties remained stable for the duration of the study at 63 days. The initial decrease in mechanical properties was attributed to a combination of the plasticisation effect of water and degradation of the fibre-matrix interface, with the subsequent linear behaviour being attributed to the chemical durability of P40 fibres. P40 composite rods showed low degradation and ion release rates, good biocompatibility and maintained mechanical properties similar to cortical bone for the duration of the study. Therefore, P40 composite rods have huge potential as resorbable intramedullary nails or rods.


Assuntos
Materiais Biocompatíveis/farmacologia , Vidro/química , Teste de Materiais/métodos , Células-Tronco Mesenquimais/citologia , Fosfatos/química , Ânions , Cátions , Diferenciação Celular/efeitos dos fármacos , Proliferação de Células/efeitos dos fármacos , Força Compressiva/efeitos dos fármacos , Humanos , Concentração de Íons de Hidrogênio , Ácido Láctico/farmacologia , Células-Tronco Mesenquimais/efeitos dos fármacos , Microscopia Eletrônica de Varredura , Peso Molecular , Poliésteres , Polímeros/farmacologia , Resistência ao Cisalhamento/efeitos dos fármacos , Coloração e Rotulagem , Fatores de Tempo
16.
J Mech Behav Biomed Mater ; 18: 108-22, 2013 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-23262309

RESUMO

Bioresorbable screws have the potential to overcome some of the complications associated with metallic screws currently in use. Removal of metallic screws after bone has healed is a serious issue which can lead to refracture due to the presence of screw holes. Poly lactic acid (PLA), fully 40 mol% P(2)O(5) containing phosphate unidirectional (P40UD) and a mixture of UD and short chopped strand random fibre mats (P40 70%UD/30%RM) composite screws were prepared via forging composite bars. Water uptake and mass loss for the composite screws manufactured increased significantly to ∼1.25% (P=0.0002) and ∼1.1% (P<0.0001), respectively, after 42 days of immersion in PBS at 37 °C. The initial maximum flexural load for P40 UD/RM and P40 UD composite screws was ∼60% (P=0.0047) and ∼100% (P=0.0037) higher than for the PLA screws (∼190 N), whilst the shear load was slightly higher in comparison to PLA (∼2.2 kN). The initial pull-out strengths for the P40 UD/RM and PLA screws were similar whereas that for P40 UD screws was ∼75% higher (P=0.022). Mechanical properties for the composite screws decreased initially after 3 days of immersion and this reduction was ascribed to the degradation of the fibre/matrix interface. After 3 days interval the mechanical properties (flexural, shear and pull-out) maintained their integrity for the duration of the study (at 42 days). This property retention was attributed to the chemical durability of the fibres used and stability of the matrix properties during the degradation process. It was also deemed necessary to enhance the fibre/matrix interface via use of a coupling agent in order to maintain the initial mechanical properties acquired for the required period of time. Lastly, it is also suggested that the degrading reinforcement fibres may have the potential to buffer any acidic products released from the PLA matrix.


Assuntos
Materiais Biocompatíveis , Parafusos Ósseos , Teste de Materiais/métodos , Desenho de Prótese/métodos , Resistência ao Cisalhamento , Ácido Láctico/química , Poliésteres , Ácido Poliglicólico/química , Polímeros/química , Falha de Prótese
17.
J Mech Behav Biomed Mater ; 17: 76-88, 2013 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-23122715

RESUMO

Use of bioresorbable screws could eliminate disadvantages associated with metals such as removal operations, corrosion, MRI interference and stress shielding. Mechanical properties of bioresorbable polymers alone are insufficient for load bearing applications application as screws. Thus, reinforcement is necessary to try and match or surpass the mechanical properties of cortical bone. Phosphate based glass fibres were used to reinforce polylactic acid (PLA) in order to produce unidirectionally aligned (UD) and unidirectionally plus randomly distributed (UD/RM) composite screws (P40 UD and P40 UD/RM). The maximum flexural and push-out properties for the composite screws (P40 UD and P40 UD/RM) increased by almost 100% in comparison with the PLA screws. While the pull-out strength and stiffness of the headless composite screws were ∼80% (strength) and ∼130% (stiffness) higher than for PLA, those with heads exhibited properties lower than those for PLA alone as a result of failure at the heads. An increase in the maximum shear load and stiffness for the composite screws (∼30% and ∼40%) in comparison to the PLA screws was also seen. Maximum torque for the PLA screws was ∼1000 mN m, while that for the composite screws were slightly lower. The SEM micrographs for P40 UD and P40 UD/RM screws revealed small gaps around the fibres, which were suggested to be due to buckling of the UD fibres during the manufacturing process.


Assuntos
Materiais Biocompatíveis/química , Parafusos Ósseos , Vidro/química , Ácido Láctico/química , Teste de Materiais , Fenômenos Mecânicos , Fosfatos/química , Polímeros/química , Poliésteres , Resistência ao Cisalhamento , Torque
18.
J Mater Sci Mater Med ; 23(10): 2531-41, 2012 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-22760401

RESUMO

Six phosphate glass formulations (in the system P(2)O(5)-CaO-MgO-Na(2)O-Fe(2)O(3)) were produced with fixed magnesium and calcium content at 24 and 16 mol%, respectively. P(2)O(5) and Fe(2)O(3) were varied between 40-50 and 0-4 mol% respectively, with the balance being Na(2)O. EDX analyses confirmed the final composition of the glasses investigated to within a 1-2 % error margin. Thermal analyses showed a linear increase in T(g) with increasing Fe(2)O(3) and P(2)O(5) contents, with Fe(2)O(3) showing a greater effect than P(2)O(5). This was proposed to be due to the formation of Fe-O-P bonds and an increase in the cross-link density of the glass network enhancing the durability of the glass. The glasses that were investigated revealed a decrease in degradation rate with increasing Fe(2)O(3) and P(2)O(5) contents and again the effect of Fe(2)O(3) was greater. All the above characteristics correlated well with structural changes measured by IR and XPS analyses. Cytocompatibility studies showed good cellular (MG63) response to the glasses up to 168 h in terms of cell viability, proliferation and differentiation. Statistical analysis revealed that all the formulations with the exception of P50Fe4 gave a comparable response to the control (TCP), which suggested that after a threshold level of glass durability is achieved the degradation rate has no or minimal effect on biocompatibility. However, it was seen that the glass chemistry can also affect cellular response, since increasing the P(2)O(5) content promoted phenotypic expression that was not related to degradation rate but to the degradation products. This was supported using an elution assay.


Assuntos
Materiais Biocompatíveis , Vidro , Fosfatase Alcalina/metabolismo , Linhagem Celular Tumoral , Humanos , Espectrometria por Raios X , Espectroscopia de Infravermelho com Transformada de Fourier
19.
J Dairy Sci ; 95(1): 272-85, 2012 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-22192207

RESUMO

High-sugar grass varieties have received considerable attention for their potential ability to decrease N excretion in cattle. However, feeding high-sugar grasses alters the pattern of rumen fermentation, and no in vivo studies to date have examined this strategy with respect to another environmental pollutant: methane (CH(4)). Modeling allows us to examine potential outcomes of feeding strategies under controlled conditions, and can provide a useful framework for the development of future experiments. The purpose of the present study was to use a modeling approach to evaluate the effect of high-sugar grasses on simulated CH(4) emissions in dairy cattle. An extant dynamic, mechanistic model of enteric fermentation and intestinal digestion was used for this evaluation. A simulation database was constructed and analysis of model behavior was undertaken to simulate the effect of (1) level of water-soluble carbohydrate (WSC) increase in dietary dry matter, (2) change in crude protein (CP) and neutral detergent fiber (NDF) content of the plant with an increased WSC content, (3) level of N fertilization, and (4) presence or absence of grain feeding. Simulated CH(4) emissions tended to increase with increased WSC content when CH(4) was expressed as megajoules per day or percent of gross energy intake, but when CH(4) was expressed in terms of grams per kilogram of milk, results were much more variable due to the potential increase in milk yield. As a result, under certain conditions, CH(4) (g/kg of milk) decreased. The largest increases in CH(4) emissions (MJ/d or % gross energy intake) were generally seen when WSC increased at the expense of CP in the diet and this can largely be explained by the representation in the model of the type of volatile fatty acid produced. Effects were lower when WSC increased at the expense of NDF, and intermediary when WSC increased at the expense of a mixture of CP and NDF. When WSC increased at the expense of NDF, simulated milk yield increased and, therefore, CH(4) (g/kg of milk) tended to decrease. Diminished increases of CH(4) (% gross energy intake or g/kg of milk) were simulated when DMI was increased with elevated WSC content. Simulation results suggest that high WSC grass, as a strategy to mitigate N emission, may increase CH(4) emissions, but that results depend on the grass composition, DMI, and the units chosen to express CH(4). Overall, this project demonstrates the usefulness of modeling for hypothesis testing in the absence of observed experimental results.


Assuntos
Dieta/veterinária , Metano/biossíntese , Poaceae , Animais , Bovinos , Ácidos Graxos Voláteis/metabolismo , Feminino , Fermentação , Lactação , Modelos Biológicos , Rúmen/metabolismo
20.
J Mech Behav Biomed Mater ; 4(7): 1462-72, 2011 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-21783156

RESUMO

Several studies have investigated self-reinforced polylactic acid (SR-PLA) and polyglycolic acid (SR-PGA) rods which could be used as intramedullary (IM) fixation devices to align and stabilise bone fractures. This study investigated totally bioresorbable composite rods manufactured via compression moulding at ~100 °C using phosphate glass fibres (of composition 50P(2)O(5)-40CaO-5Na(2)O-5Fe(2)O(3) in mol%) to reinforce PLA with an approximate fibre volume fraction (v(f)) of 30%. Different fibre architectures (random and unidirectional) were investigated and pure PLA rods were used as control samples. The degradation profiles and retention of mechanical properties were investigated and PBS was selected as the degradation medium. Unidirectional (P50 UD) composite rods had 50% higher initial flexural strength as compared to PLA and 60% higher in comparison to the random mat (P50 RM) composite rods. Similar initial profiles for flexural modulus were also seen comparing the P50 UD and P50 RM rods. Higher shear strength properties were seen for P50 UD in comparison to P50 RM and PLA rods. However, shear stiffness values decreased rapidly (after a week) whereas the PLA remained approximately constant. For the compressive strength studies, P50 RM and PLA rods remained approximately constant, whilst for the P50 UD rods a significantly higher initial value was obtained, which decreased rapidly after 3 days immersion in PBS. However, the mechanical properties decreased after immersion in PBS as a result of the plasticisation effect of water within the composite and degradation of the fibres. The fibres within the random and unidirectional composite rods (P50 RM and P50 UD) degraded leaving behind microtubes as seen from the SEM micrographs (after 28 days degradation) which in turn created a porous structure within the rods. This was the main reason attributed for the increase seen in mass loss and water uptake for the composite rods (~17% and ~16%, respectively).


Assuntos
Implantes Absorvíveis , Força Compressiva , Fixadores Internos , Resistência ao Cisalhamento , Módulo de Elasticidade , Vidro/química , Ácido Láctico/química , Fosfatos/química , Poliésteres , Polímeros/química , Temperatura , Fatores de Tempo
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