Synthesis of β, γ- PVDF through electrospinning for piezoelectric force sensing application.

In the present study, PVDF nanofibers containing β and γ-phases have been synthesized by electrospinning process. An experimental study was conducted for evaluating the high temperature effects on sample precursor preparation as well as PVDF phase transition (α=>β phase and α=> γ phase). High temperature melting process was employed to prepare PVDF solution as precursor for electrospinning and a typical process condition was mainatained to draw PVDF nanofiber. Synthesized fibers were characterized by fourier-transfonn infrared spectroscopy (FTIR), field emission scanning electron microscopy (FE-SEM) and X-Ray diffraction (XRD). To measure the sensing performance of the PVDF nanofibers, a piezoelectric force sensor device was constructed using these fibers. The voltage vs current and voltage vs time signals were recorded against calibrated loads using digital oscilloscope. More specifically, it was established that precursors melted at 150°C temperature is essential for producing β+γ mixed crystal based PVDF nanofibers which could generate signals of sufficiently high amplitude at low applied forces consistent with the physical acoustic theory

Glassy carbon as a novel mould material for replicative forming of precision glass optics.

Replicative forming of precision glass optics has been fast emerging as a rapid, net shape process chain for mobile camera lenses, CD/DVD pickup lenses, microscope objectives, night vision lenses, Fresnel lenses and so on. The process involves moulding a glass gob at high temperatures exceeding the glass transition temperature using a predefined loading and thermal cycle. Typically, the mould material is required to have high strength, low thermal expansion, chemical inertness and anti-adhesion properties, especially at high temperatures. Traditional mould materials, such as, invar or tungsten carbide are difficult to machine which adversely affects the cost of the entire process. In the present work, glassy carbon mould has been developed using p-tolune sulfonic acid (PTSA) cured phenolic resin by a process of carbonization where the composition ratio of phenolic resin and PTSA solution was standardised accompanied by the pyrolysing conditions. Detailed characterisation of the phase evolution, surface compositions, morphology and mechanical parameters of the glassy carbon has been conducted by X-Ray diffraction (XRD) technique, Raman Spectral (RS) analysis, X-ray Photoelectron Spectroscopy (XPS), Field Emission Scanning Electron microscope (FESEM), Energy Dispersive Spectroscopy (EDX) and Nanomechanical testing which reveal an optimal combination of properties of the glassy carbon that makes it an attractive low cost mould material for replicative forming process chain of glass optics fabrication

Synthesis of ultra-high temperature silicon oxycarbide (SiOC) glass by an organic-inorganic hybrid route

Silicon oxycarbide is a new generation amorphous glassy ceramic possessing unique electrical, mechanical, optical properties and ultra-high temperature stability upto 2730°C. It has numerous engineering applications in additive manufacturing, lithium-ion batteries, brake disks for sports car, ultra-fast and high voltage LEDs, MOSFETs, thyristors for high power switching, astronomical telescope, nuclear power reactor etc. In this work, SiOC was prepared by sol-gel technique using organic-inorganic hybrids as precursors. Tetraethoxysilane (TEOS) and Polydimethylsiloxane (PDMS) were used as silica and carbon sources respectively. SiOC sols were formed through hydrolysis of TEOS and PDMS. The used chemicals in this process involved isopropanol, distilled water and hydrochloric acid, which is used here as solvent, hydrolytic agent and catalyst respectively, at different refluxing condition, alkoxide to water ratios, pH levels etc. The sols thus formed were allowed to gel over a varying period (up to maximum of 10 days). After drying the gels for 24 hours, the same was pyrolysed at 1100°C under inert nitrogen atmosphere to yield SiOC. Phase formation was carried out by X-Ray Diffraction (XRD) technique, X-ray Photoelectron Spectroscopy (XPS) analysis and Raman Spectroscopic analysis. XRD data showed formation of a broad peak at 2θ~22 degrees indicating formation of amorphous SiOC and absence of any crystalline peaks indicating no SiC or Si was formed during pyrolysis. XPS data shows the presence of Si, O and C peaks in the range 100-200 eV, 530 eV and 285 eV, respectively, confirming formation of SiOC. It was revealed that within the random network of Si-O tetrahedra, islands of only C-C bonds were responsible for coloring the SiOC glass black. The estimation of mechanical properties revealed that the hardness value and Young’s modulus, of the synthesized SiOC ceramic sample, was determined to be 11.67 GPa and 75.79 respectively which indicating the better mechanical properties than other reported SiOC systems

Effects of antiplatelet therapy on stroke risk by brain imaging features of intracerebral haemorrhage and cerebral small vessel diseases: subgroup analyses of the RESTART randomised, open-label trial

Background Findings from the RESTART trial suggest that starting antiplatelet therapy might reduce the risk of recurrent symptomatic intracerebral haemorrhage compared with avoiding antiplatelet therapy. Brain imaging features of intracerebral haemorrhage and cerebral small vessel diseases (such as cerebral microbleeds) are associated with greater risks of recurrent intracerebral haemorrhage. We did subgroup analyses of the RESTART trial to explore whether these brain imaging features modify the effects of antiplatelet therapy

Effects of antiplatelet therapy after stroke due to intracerebral haemorrhage (RESTART): a randomised, open-label trial

Background: Antiplatelet therapy reduces the risk of major vascular events for people with occlusive vascular disease, although it might increase the risk of intracranial haemorrhage. Patients surviving the commonest subtype of intracranial haemorrhage, intracerebral haemorrhage, are at risk of both haemorrhagic and occlusive vascular events, but whether antiplatelet therapy can be used safely is unclear. We aimed to estimate the relative and absolute effects of antiplatelet therapy on recurrent intracerebral haemorrhage and whether this risk might exceed any reduction of occlusive vascular events. Methods: The REstart or STop Antithrombotics Randomised Trial (RESTART) was a prospective, randomised, open-label, blinded endpoint, parallel-group trial at 122 hospitals in the UK. We recruited adults (≥18 years) who were taking antithrombotic (antiplatelet or anticoagulant) therapy for the prevention of occlusive vascular disease when they developed intracerebral haemorrhage, discontinued antithrombotic therapy, and survived for 24 h. Computerised randomisation incorporating minimisation allocated participants (1:1) to start or avoid antiplatelet therapy. We followed participants for the primary outcome (recurrent symptomatic intracerebral haemorrhage) for up to 5 years. We analysed data from all randomised participants using Cox proportional hazards regression, adjusted for minimisation covariates. This trial is registered with ISRCTN (number ISRCTN71907627). Findings: Between May 22, 2013, and May 31, 2018, 537 participants were recruited a median of 76 days (IQR 29–146) after intracerebral haemorrhage onset: 268 were assigned to start and 269 (one withdrew) to avoid antiplatelet therapy. Participants were followed for a median of 2·0 years (IQR [1·0– 3·0]; completeness 99·3%). 12 (4%) of 268 participants allocated to antiplatelet therapy had recurrence of intracerebral haemorrhage compared with 23 (9%) of 268 participants allocated to avoid antiplatelet therapy (adjusted hazard ratio 0·51 [95% CI 0·25–1·03]; p=0·060). 18 (7%) participants allocated to antiplatelet therapy experienced major haemorrhagic events compared with 25 (9%) participants allocated to avoid antiplatelet therapy (0·71 [0·39–1·30]; p=0·27), and 39 [15%] participants allocated to antiplatelet therapy had major occlusive vascular events compared with 38 [14%] allocated to avoid antiplatelet therapy (1·02 [0·65–1·60]; p=0·92). Interpretation: These results exclude all but a very modest increase in the risk of recurrent intracerebral haemorrhage with antiplatelet therapy for patients on antithrombotic therapy for the prevention of occlusive vascular disease when they developed intracerebral haemorrhage. The risk of recurrent intracerebral haemorrhage is probably too small to exceed the established benefits of antiplatelet therapy for secondary prevention

Effects of antiplatelet therapy after stroke due to intracerebral haemorrhage (RESTART): a randomised, open-label trial

Background: Antiplatelet therapy reduces the risk of major vascular events for people with occlusive vascular disease, although it might increase the risk of intracranial haemorrhage. Patients surviving the commonest subtype of intracranial haemorrhage, intracerebral haemorrhage, are at risk of both haemorrhagic and occlusive vascular events, but whether antiplatelet therapy can be used safely is unclear. We aimed to estimate the relative and absolute effects of antiplatelet therapy on recurrent intracerebral haemorrhage and whether this risk might exceed any reduction of occlusive vascular events. Methods: The REstart or STop Antithrombotics Randomised Trial (RESTART) was a prospective, randomised, open-label, blinded endpoint, parallel-group trial at 122 hospitals in the UK. We recruited adults (≥18 years) who were taking antithrombotic (antiplatelet or anticoagulant) therapy for the prevention of occlusive vascular disease when they developed intracerebral haemorrhage, discontinued antithrombotic therapy, and survived for 24 h. Computerised randomisation incorporating minimisation allocated participants (1:1) to start or avoid antiplatelet therapy. We followed participants for the primary outcome (recurrent symptomatic intracerebral haemorrhage) for up to 5 years. We analysed data from all randomised participants using Cox proportional hazards regression, adjusted for minimisation covariates. This trial is registered with ISRCTN (number ISRCTN71907627). Findings: Between May 22, 2013, and May 31, 2018, 537 participants were recruited a median of 76 days (IQR 29–146) after intracerebral haemorrhage onset: 268 were assigned to start and 269 (one withdrew) to avoid antiplatelet therapy. Participants were followed for a median of 2·0 years (IQR [1·0– 3·0]; completeness 99·3%). 12 (4%) of 268 participants allocated to antiplatelet therapy had recurrence of intracerebral haemorrhage compared with 23 (9%) of 268 participants allocated to avoid antiplatelet therapy (adjusted hazard ratio 0·51 [95% CI 0·25–1·03]; p=0·060). 18 (7%) participants allocated to antiplatelet therapy experienced major haemorrhagic events compared with 25 (9%) participants allocated to avoid antiplatelet therapy (0·71 [0·39–1·30]; p=0·27), and 39 [15%] participants allocated to antiplatelet therapy had major occlusive vascular events compared with 38 [14%] allocated to avoid antiplatelet therapy (1·02 [0·65–1·60]; p=0·92). Interpretation: These results exclude all but a very modest increase in the risk of recurrent intracerebral haemorrhage with antiplatelet therapy for patients on antithrombotic therapy for the prevention of occlusive vascular disease when they developed intracerebral haemorrhage. The risk of recurrent intracerebral haemorrhage is probably too small to exceed the established benefits of antiplatelet therapy for secondary prevention

Effects of antiplatelet therapy after stroke due to intracerebral haemorrhage (RESTART): a randomised, open-label trial

BACKGROUND: Antiplatelet therapy reduces the risk of major vascular events for people with occlusive vascular disease, although it might increase the risk of intracranial haemorrhage. Patients surviving the commonest subtype of intracranial haemorrhage, intracerebral haemorrhage, are at risk of both haemorrhagic and occlusive vascular events, but whether antiplatelet therapy can be used safely is unclear. We aimed to estimate the relative and absolute effects of antiplatelet therapy on recurrent intracerebral haemorrhage and whether this risk might exceed any reduction of occlusive vascular events. METHODS: The REstart or STop Antithrombotics Randomised Trial (RESTART) was a prospective, randomised, open-label, blinded endpoint, parallel-group trial at 122 hospitals in the UK. We recruited adults (≥18 years) who were taking antithrombotic (antiplatelet or anticoagulant) therapy for the prevention of occlusive vascular disease when they developed intracerebral haemorrhage, discontinued antithrombotic therapy, and survived for 24 h. Computerised randomisation incorporating minimisation allocated participants (1:1) to start or avoid antiplatelet therapy. We followed participants for the primary outcome (recurrent symptomatic intracerebral haemorrhage) for up to 5 years. We analysed data from all randomised participants using Cox proportional hazards regression, adjusted for minimisation covariates. This trial is registered with ISRCTN (number ISRCTN71907627). FINDINGS: Between May 22, 2013, and May 31, 2018, 537 participants were recruited a median of 76 days (IQR 29-146) after intracerebral haemorrhage onset: 268 were assigned to start and 269 (one withdrew) to avoid antiplatelet therapy. Participants were followed for a median of 2·0 years (IQR [1·0- 3·0]; completeness 99·3%). 12 (4%) of 268 participants allocated to antiplatelet therapy had recurrence of intracerebral haemorrhage compared with 23 (9%) of 268 participants allocated to avoid antiplatelet therapy (adjusted hazard ratio 0·51 [95% CI 0·25-1·03]; p=0·060). 18 (7%) participants allocated to antiplatelet therapy experienced major haemorrhagic events compared with 25 (9%) participants allocated to avoid antiplatelet therapy (0·71 [0·39-1·30]; p=0·27), and 39 [15%] participants allocated to antiplatelet therapy had major occlusive vascular events compared with 38 [14%] allocated to avoid antiplatelet therapy (1·02 [0·65-1·60]; p=0·92). INTERPRETATION: These results exclude all but a very modest increase in the risk of recurrent intracerebral haemorrhage with antiplatelet therapy for patients on antithrombotic therapy for the prevention of occlusive vascular disease when they developed intracerebral haemorrhage. The risk of recurrent intracerebral haemorrhage is probably too small to exceed the established benefits of antiplatelet therapy for secondary prevention. FUNDING: British Heart Foundation

Synthesis and Characterization of ZnO Microfiber By Electrospinning Technique

Ultrathin 1D assembly of pure crystalline ZnO microfibers were fabricated using facile, low-cost electrospinning technique. Nanofibrous membrane preforms were synthesized by electrospinning a ZnO precursor containing PVA solution in aqueous medium. The crystalline ZnO microfibers were obtained by calcining PVA/Zinc Acetate precursor fibers at 500 degrees C. The structure and morphologies of ZnO microfibers were studied by X-ray diffraction (XRD), thermogravimetric analysis (TGA) and field emission scanning electron microscopy (FE-SEM). (C) 2017 Elsevier Ltd. All rights reserved. Selection and/or Peer-review under responsibility of International Conference on Functional Nano-Materials, 2016

A new method for estimation of elastic properties of sintered iron powder compacts from ultrasonic longitudinal velocity

A new methodology has been proposed for estimation of elastic moduli of iron powder compacts solely based on longitudinal ultrasonic velocity. New correlations have been semianalytically derived between the elastic moduli and the longitudinal ultrasonic velocity. The moduli estimated on the basis of the suggested methodology agreed reasonably well with data reported for iron powder compacts in the literature. The proposed method can be a potent tool for quick and accurate, nondestructive estimation of elastic properties for porous materials through ultrasonic measurements