Oxygen Diffusion Layer on Ti–6Al–4V Alloy: Scratch and Dry Wear Resistance

Ti–6Al–4V has prominent physical and mechanical properties, which nominate it for various engineering applications. A drawback of the alloy, however, is low scratch and wear resistance, which can be improved by a diffusion treatment. Oxygen diffusion layer (ODL) was produced on Ti–6Al–4V by thermal oxidation at a temperature of 850 °C for 3 and 6 h. Hardness of the samples was measured using a nano-indentation tester. Micro-scratch tests were performed under progressive and constant normal loads of 0–50 N. Dry wear behavior of the samples was studied using a ball-on-disk tribometer. The wear tests were carried out under various normal loads of 7.5, 15 and 30 N for sliding distances of 50, 100, 200 and 300 m using alumina balls as the counterface. The wear and scratch tracks were examined by scanning electron microscope and surface profilometer. The ODL samples showed higher hardness and lower plastic deformation as compared with Ti–6Al–4V. The brittle behavior of the ODL samples caused the formation of cracks and the development of large acoustic signals during scratching under normal loads of 40 and 50 N. The results also showed a higher scratch and wear resistance of the ODL samples compared with Ti–6Al–4V. However, the oxygen diffusion layer formed after 3 h of oxidation showed a sharp increase in the wear rate of the alloy under a normal load of 30 N and a sliding distance of 100 m

Bio-corrosion behaviour of oxygen diffusion layer on Ti-6Al-4V during tribocorrosion

Oxygen diffusion layers (ODL) on Ti-6Al-4V were produced by thermal oxidation at a temperature of 850 °C for three and six hours. ODL formation resulted in a β-Ti to α-Ti transformation, causing an increase in hardness. Polarization and EIS studies in stagnant and tribocorrosion conditions were performed under normal loads of 3–30 N in a phosphate buffered saline solution. In a stagnant condition, a passive bilayer film was formed on samples, which led to a low icorr. During tribocorrosion, the formation of a protective tribofilm resulted in a higher Ecorr and a lower icorr in ODLs compared with Ti-6Al-4V

Mechanism of tribofilm formation on Ti6Al4V oxygen diffusion layer in a simulated body fluid

An Oxygen Diffusion Layer (ODL) was generated on the surface of Ti6Al4V alloy by thermal oxidation treatment. In vitro tests for cytotoxicity were performed in the presence of Ti6Al4V and the ODL samples with the culture of G292 Cells and using MTT assay. The results showed a similar cell viability in the presence of the both samples. Wear behavior of Ti6Al4V and the ODL samples was investigated in a phosphate buffered saline solution under a normal load of 30 N at a sliding velocity of 0.1 m/s. The worn surface and subsurface of the samples were studied using SEM, STEM, TEM, XPS, AFM, nano-hardness and surface profilometry. A bio-tribofilm was observed on the worn surface of the ODL. TEM studies showed that the tribofilm had an amorphous structure and contained oxygen and phosphorous as confirmed by XPS and EDS analysis. AFM images also revealed that the tribofilm consisted of compacted fine debris. The formation of the tribofilm on the ODL with higher hardness and strength resulted in a decrease of about 95% in the wear rate compared with Ti6Al4V alloy

Surface Fatigue Behaviour of a WC/aC:H Thin-Film and the Tribochemical Impact of Zinc Dialkyldithiophosphate

In wind turbine gearboxes, (near-)surface initiated fatigue is attributed to be the primary failure mechanism. In this work, the surface fatigue of a hydrogenated tungsten carbide/amorphous carbon (WC/aC:H) thin-film was tested under severe cyclic tribo-contact using PolyAlphaOlefin (PAO) and PAO + Zinc DialkylDithioPhosphate (ZDDP) lubricants. The film was characterised in terms of its structure and chemistry using X-ray diffraction, analytical Transmission Electron Microscopy (TEM) including Electron Energy Loss Spectroscopy (EELS), as well as X-ray Photoelectron Spectroscopy (XPS). The multilayer carbon thin-film exhibited promising surface fatigue performance showing a slight change in the hybridization state of the aC:H matrix. Dehydrogenation of the thin-film and subsequent transformation of cleaved C-H bonds to non planar sp2 carbon rings were inferred from EELS and XPS results. Whilst tribo-induced changes to the aC:H matrix were not influenced by a nanometer-thick ZDDP reaction-film, the rate of oxidation of WC and its oxidation state were affected. Whilst accelerating surface fatigue on a steel surface, the ZDDP-tribofilm protected the WC/aC:H film from surface fatigue. In contrast to the formation of polyphosphates from ZDDP molecules on steel surfaces, it appeared that on the WC/aC:H thin film surface ZDDP molecules decompose to ZnO suppressing the oxidative degradation of WC

Rapid neurogenesis through transcriptional activation in human stem cells

Advances in cellular reprogramming and stem cell differentiation now enable ex vivo studies of human neuronal differentiation. However, it remains challenging to elucidate the underlying regulatory programs because differentiation protocols are laborious and often result in low neuron yields. Here, we overexpressed two Neurogenin transcription factors in human-induced pluripotent stem cells and obtained neurons with bipolar morphology in 4 days, at greater than 90% purity. The high purity enabled mRNA and microRNA expression profiling during neurogenesis, thus revealing the genetic programs involved in the rapid transition from stem cell to neuron. The resulting cells exhibited transcriptional, morphological and functional signatures of differentiated neurons, with greatest transcriptional similarity to prenatal human brain samples. Our analysis revealed a network of key transcription factors and microRNAs that promoted loss of pluripotency and rapid neurogenesis via progenitor states. Perturbations of key transcription factors affected homogeneity and phenotypic properties of the resulting neurons, suggesting that a systems-level view of the molecular biology of differentiation may guide subsequent manipulation of human stem cells to rapidly obtain diverse neuronal types

IMCI and ETAT Integration at a Primary Healthcare Facility in Malawi:A Human Factors Approach

Abstract Background Integrated Management of Childhood Illness (IMCI) and Emergency Triage, Assessment and Treatment (ETAT) are guidelines developed by the World Health Organization to reach targets for reducing under-5 mortality. They were set out in the Millennium Development Goals. Each guideline was established separately so the purpose of this study was to understand how these systems have been integrated in a primary care setting and identify barriers and facilitators to this integration using a systems approach. Method Interviews were carried out with members of staff of different levels within a primary healthcare clinic in Malawi. Along with observations from the clinic this provided a well-rounded view of the running of the clinic. This data was then analysed using the SEIPS 2.0 work systems framework. The work system elements specified in this model were used to identify and categorise themes that influenced the clinic’s efficiency. Results A process map of the flow of patients through the clinic was created, showing the tasks undertaken and the interactions between staff and patients. In their interviews, staff identified several organisational elements that served as barriers to the implementation of care. They included workload, available resources, ineffective time management, delegation of roles and adaptation of care. In terms of the external environment there was a lack of clarity over the two sets of guidelines and how they were to be integrated which was a key barrier to the process. Under the heading of tools and technology a lack of guideline copies was identified as a barrier. However, the health passport system and other forms of recording were highlighted as being important facilitators. Other issues highlighted were the lack of transport provided, challenges regarding teamwork and attitudes of members of staff, patient factors such as their beliefs and regard for the care and education provided by the clinic. Conclusions This study provides the first information on the challenges and issues involved in combining IMCI and ETAT and identified a number of barriers. These barriers included a lack of resources, staff training and heavy workload. This provided areas to work on in order to improve implementation

Updated meta-review of evidence on support for carers

Abstract Background Policy and research interest in carers continues to grow. A previous meta-review, published in 2010, by Parker et al. (Parker G, Arksey H, Harden M. Meta-review of International Evidence on Interventions to Support Carers. York: Social Policy Research Unit, University of York; 2010) found little compelling evidence of effectiveness about specific interventions and costs. Objective To update what is known about effective interventions to support carers of ill, disabled or older adults. Design Rapid meta-review. Setting Any relevant to the UK health and social care system. Participants Carers (who provide support on an unpaid basis) of adults who are ill, disabled or older. Interventions Any intervention primarily aimed at carers. Main outcome measures Any direct outcome for carers. Data sources Database searches (including Cochrane Database of Systematic Reviews, Database of Abstracts of Reviews of Effects, MEDLINE, Applied Social Sciences Index and Abstracts and Social Care Online) for systematic reviews published from January 2009 to 2016. Review methods We used EndNote X7.4 (Thomson Reuters, CA, USA) to screen titles and abstracts. Final decisions on the inclusion of papers were made by two reviewers independently, using a Microsoft Excel® 2013 spreadsheet (Microsoft Corporation, Redmond, WA, USA). We carried out a narrative synthesis structured by patient condition and by seven outcomes of interest. We assessed the quality of the included systematic reviews using established criteria. We invited a user group of carers to give their views on the overall findings of our review. Results Sixty-one systematic reviews were included (27 of high quality, 25 of medium quality and nine of low quality). Patterns in the literature were similar to those in earlier work. The quality of reviews had improved, but primary studies remained limited in quality and quantity. Of the high-quality reviews, 14 focused on carers of people with dementia, four focused on carers of those with cancer, four focused on carers of people with stroke, three focused on carers of those at the end of life with various conditions and two focused on carers of people with mental health problems. Multicomponent interventions featured prominently, emphasising psychosocial or psychoeducational content, education and training. Multiple outcomes were explored, primarily in mental health, burden and stress, and well-being or quality of life. Negative effects following respite care were unsupported by our user group. As with earlier work, we found little evidence on intervention cost-effectiveness. No differences in review topics were found across high-, medium- and low-quality reviews. Limitations The nature of meta-reviews precludes definitive conclusions about intervention effectiveness, for whom and why. Many of the included reviews were small in size and authors generally relied on small numbers of studies to underpin their conclusions. The meta-review was restricted to English-language publications. Short timescales prevented any investigation of the overlap of primary studies, and growth in the evidence base since the original meta-review meant that post-protocol decisions were necessary. Conclusions There is no ‘one size fits all’ intervention to support carers. Potential exists for effective support in specific groups of carers. This includes shared learning, cognitive reframing, meditation and computer-delivered psychosocial support for carers of people with dementia, and psychosocial interventions, art therapy and counselling for carers of people with cancer. Counselling may also help carers of people with stroke. The effectiveness of respite care remains a paradox, given the apparent conflict between the empirical evidence and the views of carers. Future work More good-quality, theory-based, primary research is warranted. Evidence is needed on the differential impact of interventions for various types of carers (including young carers and carers from minority groups), and on the effectiveness of constituent parts in multicomponent programmes. Further research triangulating qualitative and quantitative evidence on respite care is urgently required. The overlap of primary studies was not formally investigated in our review, and this warrants future evaluation. Study registration This study is registered as PROSPERO CRD42016033367. Funding The National Institute for Health Research Health Services and Delivery Research programme

High Uptake of Exclusive Breastfeeding and Reduced Early Post-Natal HIV Transmission

BACKGROUND. Empirical data showing the clear benefits of exclusive breastfeeding (EBF) for HIV prevention are needed to encourage implementation of lactation support programs for HIV-infected women in low resource settings among whom replacement feeding is unsafe. We conducted a prospective, observational study in Lusaka, Zambia, to test the hypothesis that EBF is associated with a lower risk of postnatal HIV transmission than non-EBF. METHODS AND RESULTS. As part of a randomized trial of early weaning, 958 HIV-infected women and their infants were recruited and all were encouraged to breastfeed exclusively to 4 months. Single-dose nevirapine was provided to prevent transmission. Regular samples were collected from infants to 24 months of age and tested by PCR. Detailed measurements of actual feeding behaviors were collected to examine, in an observational analysis, associations between feeding practices and postnatal HIV transmission. Uptake of EBF was high with 84% of women reporting only EBF cumulatively to 4 months. Post-natal HIV transmission before 4 months was significantly lower (p = 0.004) among EBF (0.040 95% CI: 0.024–0.055) than non-EBF infants (0.102 95% CI: 0.047–0.157); time-dependent Relative Hazard (RH) of transmission due to non-EBF = 3.48 (95% CI: 1.71–7.08). There were no significant differences in the severity of disease between EBF and non-EBF mothers and the association remained significant (RH = 2.68 95% CI: 1.28–5.62) after adjusting for maternal CD4 count, plasma viral load, syphilis screening results and low birth weight. CONCLUSIONS. Non-EBF more than doubles the risk of early postnatal HIV transmission. Programs to support EBF should be expanded universally in low resource settings. EBF is an affordable, feasible, acceptable, safe and sustainable practice that also reduces HIV transmission providing HIV-infected women with a means to protect their children's lives. TRIAL REGISTRATION. ClinicalTrials.gov NCT00310726National Institute of Child Health and Human Development; National Institutes of Health (R01 HD 39611, R01 HD 40777); Centers for Disease Control and Prevention; Global AIDS Program; Glaser Pediatric AIDS Foundation; USAID Country Research (GHS-A-00-00020-00

Oral Cancer Development in Patients with Leukoplakia – Clinicopathological Factors Affecting Outcome

Oral leukoplakia (OL) is the best-known potentially malignant disorder. The objective of the current study was to evaluate the clinicopathological factors predictive of outcome in a large cohort of patients with OL, and report our experience in the early detection of malignant events.A total of 320 patients with biopsy-proven OL were retrospectively reviewed from the study institution who had a mean follow-up of 5.1 years. Data on patient and lesion at initial diagnosis and patient underwent sequential biopsies were reviewed. Multiple biopsies indicates > = 3 times sequential biopsies. Oral cancer-free survival rate (OCFS) was determined by the Kaplan-Meier method and significant factors were identified by Cox regression analysis.<0.001), especially during the first 2–3 years of follow-up. Multivariate analysis revealed that the 4 factors including patient aged >60 years, lesion located at lateral/ventral tongue, non-homogenous lesion, high-grade dysplasia were independent significant indicators for OL malignant transformation. In addition, significant positive correlation between the multiple biopsies and these 4 factors and malignant outcome was established.Elderly patients with OL located at lateral/ventral tongue and who had non-homogenous lesion with high-grade dysplasia correlated much higher risk of transformation. This high-risk subpopulation was suggested to undergo sequential biopsies and histologic examination contributing to early detection of malignant event

Molecular Prognostic Prediction for Locally Advanced Nasopharyngeal Carcinoma by Support Vector Machine Integrated Approach

BACKGROUND:Accurate prognostication of locally advanced nasopharyngeal carcinoma (NPC) will benefit patients for tailored therapy. Here, we addressed this issue by developing a mathematical algorithm based on support vector machine (SVM) through integrating the expression levels of multi-biomarkers. METHODOLOGY/PRINCIPAL FINDINGS:Ninety-seven locally advanced NPC patients in a randomized controlled trial (RCT), consisting of 48 cases serving as training set and 49 cases as testing set of SVM models, with 5-year follow-up were studied. We designed SVM models by selecting the variables from 38 tissue molecular biomarkers, which represent 6 tumorigenesis signaling pathways, and 3 EBV-related serological biomarkers. We designed 3 SVM models to refine prognosis of NPC with 5-year follow-up. The SVM1 displayed highly predictive sensitivity (sensitivity, specificity were 88.0% and 81.9%, respectively) by integrating the expression of 7 molecular biomarkers. The SVM2 model showed highly predictive specificity (sensitivity, specificity were 84.0% and 94.5%, respectively) by grouping the expression level of 12 molecular biomarkers and 3 EBV-related serological biomarkers. The SVM3 model, constructed by combination SVM1 with SVM2, displayed a high predictive capacity (sensitivity, specificity were 88.0% and 90.3%, respectively). We found that 3 SVM models had strong power in classification of prognosis. Moreover, Cox multivariate regression analysis confirmed these 3 SVM models were all the significant independent prognostic model for overall survival in testing set and overall patients. CONCLUSIONS/SIGNIFICANCE:Our SVM prognostic models designed in the RCT displayed strong power in refining patient prognosis for locally advanced NPC, potentially directing future target therapy against the related signaling pathways