Phase transformation behaviour of porous NiTi alloys fabricated by capsule-free hot isostatic pressing

Differential scanning calorimetry (DSC) was used to characterize the phase transformation behaviour of porous Ni50Ti50 alloys fabricated by capsule-free hot isostatic pressing (CF-HIP) with different cold compaction pressures. Experimental results reveal that a multi-stage martensitic transformation (MST) exists in the sintered porous NiTi alloys on cooling while the reverse transformation upon heating is either a single or two-stage phase transformation. The DSC thermal analysis indicates that the cold compaction pressure has great effect on the subsequent transformation temperatures. Generally, the phase transformation temperatures of porous NiTi alloys with lower cold compaction pressure are higher than those compacted with higher pressure. With increase in the annealing time, the transformation temperatures increase quickly when the cold compaction pressure was 150MPa. On the other hand, the transformation temperatures change only slightly when the cold compaction pressure was varied from 300MPa to 400MPa. These phenomena can be attributed to the combined effect of larger plastic deformation with higher dislocations density produced by cold compaction and the precipitation of the second phase in the porous NiTi alloys.published_or_final_versio

Biomimetic deposition of apatite on surface chemically modified porous NiTi shapememory alloy

Porous NiTi shape memory alloy (SMA) with 48% porosity and an average pore size of 50800 μm was synthesized by capsule-free hot isostatic pressing (CF-HIP). To enhance the surface bioactivity, the porous NiTi SMA was subjected to H"2O"2 and subsequent NaOH treatment. Scanning electron microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy analyses revealed that a porous sodium titanate (Na"2TiO"3) film had formed on the surface of the porous NiTi SMA. An apatite layer was deposited on this film after immersion in simulated body fluid at 37°C, while no apatite could be found on the surface of the untreated porous NiTi SMA. The formation of the apatite layer infers that the bioactivity of the porous NiTi SMA may be enhanced by surface chemical treatment, which is favorable for its application as bone implants. © 2008 World Scientific Publishing Company.postprin

An ARIMA-intervention analysis model for the financial crisis in China's manufacturing industry

2008-2009 > Academic research: refereed > Publication in refereed journalVersion of RecordPublishe

Suppression of nickel out-diffusion from porous nickel-titanium shape memory alloy by plasma immersion ion implantation

Summary form only given. Porous nickel titanium is a promising material for medical application not only because of its super elasticity and shape memory effect but also the porous structure which may enhance bone growth due to the increased surface area. It is thus especially suitable for bone tissue in-growth and fixation of biomedical implants. However, like its dense counterpart, Ni leaching from the materials causes health concern. Thus, in order to suppress Ni diffusion from the materials to body fluids and tissues in humans, a diffusion barrier or similar structure must be introduced. In this work, we produced this diffusion barrier layer by oxygen or nitrogen plasma immersion ion implantation (PIII). In vitro tests were conducted by immersing the plasma-treated NiTi into simulated body fluid (SBF) at 37plusmn0.5degC for 5 weeks and the resulting SBF was analyzed for Ni and Ti using inductively-coupled plasma mass spectrometry (ICMPS). Our results show that Ni leaching is significantly mitigated by both nitrogen and oxygen PIII.published_or_final_versio

Cerebral involvement in neuromyelitis optica spectrum disorders among Hong Kong Chinese

published_or_final_versionThe 16th Medical Resarch Conference (MRC), The University of Hong Kong, Hong Kong, China, 22 January 2011. In Hong Kong Medical Journal, 2011, v. 17, suppl. 1, p. 55, abstract no. 8

Phenotypic and functional characterization of corneal endothelial cells during in vitro expansion.

The advent of cell culture-based methods for the establishment and expansion of human corneal endothelial cells (CEnC) has provided a source of transplantable corneal endothelium, with a significant potential to challenge the one donor-one recipient paradigm. However, concerns over cell identity remain, and a comprehensive characterization of the cultured CEnC across serial passages has not been performed. To this end, we compared two established CEnC culture methods by assessing the transcriptomic changes that occur during in vitro expansion. In confluent monolayers, low mitogenic culture conditions preserved corneal endothelial cell state identity better than culture in high mitogenic conditions. Expansion by continuous passaging induced replicative cell senescence. Transcriptomic analysis of the senescent phenotype identified a cell senescence signature distinct for CEnC. We identified activation of both classic and new cell signaling pathways that may be targeted to prevent senescence, a significant barrier to realizing the potential clinical utility of in vitro expansion

Broadband on-chip polarization mode splitters in lithium niobate integrated adiabatic couplers

© 2019 Optical Society of America under the terms of the OSA Open Access Publishing Agreement. We report, to the best of our knowledge, the first broadband polarization mode splitter (PMS) based on the adiabatic light passage mechanism in the lithium niobate (LiNbO3) waveguide platform. A broad bandwidth of ~140 nm spanning telecom S, C, and L bands at polarization-extinction ratios (PER) of >20 dB and >18 dB for the TE and TM polarization modes, respectively, is found in a five-waveguide adiabatic coupler scheme whose structure is optimized by an adiabaticity engineering process in titanium-diffused LiNbO3 waveguides. When the five-waveguide PMS is integrated with a three-waveguide “shortcut to adiabaticity” structure, we realize a broadband, high splitting-ratio (ηc) mode splitter for spatial separation of TE- (H-) polarized pump (700-850 nm for ηc>99%), TM- (V-) polarized signal (1510-1630 nm for ηc>97%), and TE- (H-) polarized idler (1480-1650 nm for ηc>97%) modes. Such a unique integrated-optical device is of potential for facilitating the on-chip implementation of a pump-filtered, broadband tunable entangled quantum-state generator

Changing from face-to-face to virtual meetings due to the COVID-19 pandemic: Protocol for a mixed-methods study exploring the impact on cancer multidisciplinary team (MDT) meetings

INTRODUCTION: In the UK, the National Cancer Plan (2000) requires every cancer patient’s care to be reviewed by a multidisciplinary team (MDT). Since the introduction of these guidelines, MDTs have faced escalating demands with increasing numbers and complexity of cases. The COVID-19 pandemic has presented MDTs with the challenge of running MDT meetings virtually rather than face-to-face. This study aims to explore how the change from face-to-face to virtual MDT meetings during the COVID-19 pandemic may have impacted the effectiveness of decision-making in cancer MDT meetings and to make recommendations to improve future cancer MDT working based on the findings. METHODS AND ANALYSIS: A mixed-methods study with three parallel phases: Semistructured remote qualitative interviews with ≤40 cancer MDT members. A national cross-sectional online survey of cancer MDT members in England, using a validated questionnaire with both multiple-choice and free-text questions. Live observations of ≥6 virtual/hybrid cancer MDT meetings at four NHS Trusts. Participants will be recruited from Cancer Alliances in England. Data collection tools have been developed in consultation with stakeholders, based on a conceptual framework devised from decision-making models and MDT guidelines. Quantitative data will be summarised descriptively, and χ2 tests run to explore associations. Qualitative data will be analysed using applied thematic analysis. Using a convergent design, mixed-methods data will be triangulated guided by the conceptual framework. The study has been approved by NHS Research Ethics Committee (London—Hampstead) (22/HRA/0177). The results will be shared through peer-reviewed journals and academic conferences. A report summarising key findings will be used to develop a resource pack for MDTs to translate learnings from this study into improved effectiveness of virtual MDT meetings. The study has been registered on the Open Science Framework (https://doi.org/10.17605/OSF.IO/D2NHW)

Broadband On-Chip Adiabatic-Coupling Polarization Mode Splitters in Lithium Niobate Waveguides

© 2019 The Author(s) 2019 OSA. We report the first broadband (>120 nm at >97% splitting efficiency for both polarization modes) polarization mode-splitter in LiNbO3 adiabatic light-passage configuration. This device can facilitate the on-chip implementation of pump-filtered, broadband tunable Bell-state generators

Nickel ion level in scoliotic patients implanted with nitrogen plasma surface modified nickel-titanium superelastic spinal implant

published_or_final_versionThe 3rd International NanoElectronics Conference (INEC), Hong Kong, 3-8 January 2010. In Proceedings of the 3rd INEC, 2010, p. 136