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Introduction: Despite strong evidence that antithrombotic drugs in atrial fibrillation/flutter (AF) patients reduce stroke risk, previous emergency department (ED) pre-novel anticoagulant (NOAC) studies have shown that most discharged patients are not optimally treated. This study sought to determine baseline antithrombotic management in AF patients, and appropriate antithrombotic prescription upon ED discharge since the introduction of NOACs. Methods: Consecutive AF patients discharged by the ED physician from three academic EDs in Toronto, Canada were retrospectively identified using ECG data. Primary AF was defined as AF in patients ≥18 years without congenital heart disease or other acute medical conditions. All management and disposition decisions were left to the discretion of the emergency doctor. Results: From July 2012 to October 2014, 691 patients with primary AF were identified. Of these, 34.4% (n=238) had new onset AF and 66.4% (n=459) were discharged home directly from the ED. Of those with previously known AF (n= 453), 44.2% (n=200) were on anticoagulation at ED arrival (warfarin 59.5%, dabigatran 23.0%, rivaroxaban 11.5%); 25.6% (n=116) on antiplatelets, and 29 (6.4%) on both. Based on 2012 Canadian AF guidelines, 60.1% of those who should have received anticoagulation were receiving it. In discharged patients meeting de novo criteria for anticoagulation (n=130), 20.0% (n=26) were started on anticoagulation and 23.1% (n=30) on antiplatelets. In patients with CHADS2 score ≥ 2 (n=61), 26.2% (n=16) were started on anticoagulation. Warfarin (73.1%) was most commonly prescribed followed by dabigatran (15.4%) and rivaroxaban (11.5%). Age was the only inverse independent predictor for appropriate anticoagulation (OR 0.92 per 5 year of age 95% CI 0.89-0.95, p <0.0001) i.e. older patients were less likely to be anticoagulated. The CHADS2 score was not an independent predictor of appropriate anticoagulation. Conclusion: Our study shows a persistent gap in the antithrombotic treatment of ED AF patients irrespective of their risk.
Soybean is a leading oilseed crop in India, which contains about 40% of protein and 20% of oil. Core collection will accelerate the management and utilization of soybean genetic resources in breeding programmes. In the present study, eight agromorphological traits of 3443 soybean germplasm were analysed for the development of core collection using the principal component score (PCS) strategy and the power core method. The PCS strategy yielded core collection (CC1) of 576 accessions, which accounted for 16.72% of the entire collection (EC). The analysis based on the power core programme resulted in CC2 of 402 accessions, which accounted for 11.67% of the EC. Statistical analysis showed similar trends for the mean and range estimated in both core collections and EC. In addition, the variance, standard deviation and coefficient of variance were in general higher in core collections than in the EC. The correlations observed in the EC in general were preserved in core collections. A total of 311 and 137 unique accessions were found in CC1 and CC2 in addition to 265 accessions that were found to be common in both core collections. These 265 common accessions were the most diverse core sets, which accounted for 7.64% of the EC. We proposed to constitute an integrated core collection (ICC) by integrating both common and unique accessions. The ICC comprised 713 accessions, which accounted for about 20.62% of the EC. Statistical analysis indicated that the ICC captured maximum variation than CC1 and CC2. Therefore, the ICC can be extensively evaluated for a large number of economically important traits for the identification of desirable genotypes and for the development of mini core collection in soybean.
For over three decades, bone conduction hearing aids have been changing the lives of patients with impaired hearing. The size, appearance and fitting discomfort of early generations of bone conduction hearing aids made them unpopular. The advent of bone-anchored hearing aids in the 1970s offered patients improved sound quality and fitting comfort, due to the application of osseointegration. However, the issue of post-operative peri-abutment pin tract wound infection persisted. The Bonebridge system incorporates the first active bone conduction device, and aims to resolve peri-abutment issues. Implantation of this system in an Asian patient is presented.
We describe the fabrication and structure of nanoscale thin films of β phase shape memory alloys with the nominal atomic stoichiometry Au7Cu5Al4 (corresponding to 5.8 wt% Al). These alloys possess properties that suggest they could be used in nanoscale actuators. The films described here are between 20 and 50 nm thick which is below the thickness at which some other shape memory alloys cease to transform. However, microstructural and X-ray studies confirm that the coatings still exhibit the displacive transformations that are a prerequisite for the shape memory effect.
This paper discusses preparation, characterization and measurement of linear DC and AC magnetic properties of magnetite (Fe3O4) nanoparticles (size ranges of 7-50 nm and 5 microns) and polymer composites of those particulates. Selected data and analysis are taken from the PhD thesis of Liong . The goal of this research is to obtain magnetic data, specifically magnetization, anisotropy and coercivity as functions of particle size. These will be used as inputs to non linear magnetic simulations and in planning for future nonlinear magnetic measurements. Magnetite nanoparticles were synthesized by chemical coprecipitation, a method that allowed for the production of samples in gram quantities. Vibrating sample magnetometry was used to measure the room-temperature DC magnetization and coercivity of the particulates. Coaxial line impedance measurements were used to measure low frequency and dispersive AC permeability of Fe3O4–polymer composites from 1 Megahertz to 10 Gigahertz. AC data are applied to infer particulate magnetic susceptibility and anisotropy field change with particle size. Particle size was calculated from XTD data and supported by TEM images.
Measured DC saturation magnetization and coercivity decreased with particle dimension while anisotropy was calculated to increase. Magnetization data are consistent with models that calculate nanoparticle magnetization as a volumetric average of a spherical bulk material core and a passive outer shell. The shell thickness was calculated at 0.84 nm, very near one lattice constant of bulk Fe3O4, 0.8394 nm. Composites containing particulate volume fractions less than 20% were fabricated. Effective media theory was applied to measured AC composite permeability to extract particle magnetic properties and thereby anisotropy field, which increased by an order of magnitude from the bulk. Permeability decreased with particulate size.
Heterogeneous, one-dimensional (1D) nanomaterials, such as nanorods and nanowires, have been utilized for a variety of different biomedical applications because they offer a unique combination of properties and provide a material platform for integrating multiple functions. In this paper, we propose a template-assisted wetting approach to fabricate segmented polymer nanorods using biodegradable polymers for controlled drug delivery. Our previous work with polystyrene (PS) and poly(methyl methacrylate) (PMMA) heterogeneous, segmented nanorods is described briefly to introduce our current preliminary work with the fabrication of homogeneous biodegradable nanorods and drug release from polymer thin films. Since the template-assisted fabrication approach provides us unprecedented control over the size, spacing, and length of the heterogeneous polymer nanorods, this technique will provide for the opportunity to evaluate drug release kinetics as a function of the segment spacing, size of the nanorods, and aspect ratio in the future.
The impact of device dimension and architecture on the device performance of an all–solution fabrication organic thin film transistor (OTFT) has been investigated. The saturation drain current is inversely proportional to the channel length, indicating that a characteristic of field–effect like transistor has been obtained. In contrast, the drain current is independent of the thickness of polyvinylphenol (PVP) dielectric layer and a large leakage current is observed at the gate electrode indicating that the device also shows electrochemical transistor characteristics. Although separate conductance measurements of a single poly(3–hexylthiophene) (P3HT) layer and a P3HT/PVP layer reveal that the conductance is proportional to the thickness of the layer, the maximum achieved drain current in the fabricated OTFT is inversely proportional to the P3HT thickness. Using this data, an interface of P3HT/PVP or a maximum P3HT thickness for a working transistor of approximately 160 ± 16 nm can be extracted. The mechanism of operation of these devices is discussed.
An electrochemical capacitive sensor with electrode separation in the order of the Electrical Double Layer width (Debye length) of the analyte solution is presented for extremely sensitive and label-free analysis of Nucleic Acids. As the Electrical Double Layers (EDL) from both the capacitive electrodes interact and overlap each other in the reduced space confinement, the contribution from the electrode polarization effects and noises due to bulk sample resistance are found to be minimized. The dielectric property changes during hybridization reaction were measured using 10-mer nucleotide sequences. A 30-45% change in relative permittivity (capacitance) was observed due to DNA hybridization at 10Hz.
The current clinical treatment of cartilage defects involves autologous chondrocyte implantation into cartilage defect sites. However, one of the complications associated with this method is the lack of bonding between the implanted materials and natural tissue. Helical rosette nanotubes (HRNs) are novel biomimetic self-assembled supramolecular structures whose basic building blocks are DNA base-pairs. HRNs are similar in size to collagen in cartilage. Moreover, previous studies have shown that HRNs are biocompatible and increase the adhesion of numerous cells compared to other commonly used cartilage implant materials (like hydrogels and Ti). In addition, HRNs can solidify into a viscous gel at body temperatures under short periods of time. Thus, it is hoped that HRNs can serve as a novel in situ tissue implant to improve cartilage cell adhesion and functions. In this study, in order to heal cartilage rupture and regenerate cartilage during possible implantation, the mechanical properties of select hydrogel/HRN composites were tested. In addition, electro-spinning was used to generate three-dimensional, implantable, composite fibers encapsulated with chondrocytes and fibroblast-like type-B synoviocytes (SFB cells, a type of mesenchymal stem cell). Importantly, results showed that drug-delivered HRNs enhanced hydrogel adhesive strength and created a scaffold with nanometer-rough surface structures pertinent for cartilage regeneration. In this manner, this study provided an alternative cartilage regenerative material which relies on nanotechnology that can be injected as a liquid, solidify at body temperatures under short periods of time, have suitable mechanical properties to collagen, and promote cell functions.
This paper reports a novel and cost-effective approach which enables the integration of nanostructures and micropatterns. In this work nanofibers are selectively patterned in defined micropatterns via a collector chip. The driving momentum of the micropattern formation, namely the non-uniform electrical field, is studied by finite element method. Micropatterned nanofiber mats are successfully fabricated. The SEM characterization demonstrates that the microstructures are manifested by distinct porosities and thicknesses. This work opens a door for a broad array of applications such as nanoelectronics and tissue engineering, where the fibrous materials with the characteristic features sizes over several order of magnitudes are required.
Pulsed laser deposited cerium oxide (CeO2) nanoporous thin film on platinum (Pt) coated glass has been used for immobilization of glucose oxidase (GOx) by electrostatic interaction. Atomic force microscopy studies reveal the formation of nanoporous surface morphology of CeO2 thin film. Differential pulse voltammetric and optical measurements show that the GOx/CeO2/Pt bioelectrode is sensitive to the detection of glucose over the concentration upto 300 mg/dl. A low value of enzyme's kinetic parameter (Michaelis-Menten constant∼1.01 mM) indicates enhanced enzyme affinity of GOx to glucose.
In situ specular x-ray reflectivity was applied to study the growth kinetics of passive oxide films on iron and stainless steel substrates in pH 8.4 borate buffer solution. Under electrical potential from 0 to 800 mV, the growth rate of oxide films decreases exponentially in thickness following the direct logarithmic growth law predicted in the point defect model. The electric field in the oxide on iron is independent of the applied potentials consistent with the point defect model. In stainless steel, however, the electric field depends strongly on the applied potential indicating that the oxide properties change as the applied potential varies.
This work presents the study on the recognition and absorption of the water-soluble X-ray contrast medium iodixanol in aqueous solution using synthetic molecularly imprinted polymers (MIPs). A non-covalent imprinting technique was applied to prepare iodixanol-imprinted polymers using 4-vinylpyridine as the functional monomer and ethylene glycol dimethacrylate as the cross-linker. The effects of quantity of iodixanol templates, the crosslink density, and the solvent were studied in terms of the binding capacity and imprint effect of the polymers. UV-vis spectrometric analysis shows that the highest binding capacity achieved is 284 mg iodixanol per gram of dry polymer, which is 8.8 times higher than the binding capacity of the non-imprinted control polymers (NIPs). SEM and BET surface analysis have also been performed to investigate the effect of morphology and porosity on the binding capacities of polymers.
This paper reports on the incorporation and validation of a microagitation system based on a piezoelectric polymer, Poly(vinylidene fluoride) in its beta phase, β-PVDF, in a fully-integrated disposable lab-on-a-chip for point-of-care testing and monitoring of biochemical parameters in biological fluids. The lab-on-a-chip concept offers a novel approach for clinical analyses, especially in biological fluids analyses, due to its portability, ensuring that the analysis can be performed at any location with quick results. Its microagitation system performance was successfully demonstrated by quantitative measurements of uric acid in human urine, though other molecules or biological fluids can be also measured. The optimization tests prove that it is possible to use lower frequencies than resonance with no major changes in the mixing process. The effect of area and location within the lab-on-a-chip of the microagitation system was also considered.
There has long been a drive to produce sensors with ever-increasing sensitivity and selectivity, while also achieving robustness and ease of use. Nanoparticle-based sensing approaches have generated a great deal of attention and excitement, because they possess such qualities. For these assays to function properly, it requires the integration of molecular recognition motifs and materials with outstanding optical properties. Aptamers are DNA or RNA sequences that bind analytes with high specificity, which makes them a suitable choice as recognition elements. Changes in the surface plasmon resonance (SPR) of gold nanoparticles (AuNPS) as a function of interparticle distance, has been used as an optical signal to detect the presence of different species in solution by the naked eye. In this work, we coated gold nanoparticles with short oligonucleotides and aptamers for the design of sensors that can be used under different conditions, including salt concentration, pH and temperatures. Three aptamer sensors were developed using this approach 1) riboflavin, as a general indicator of biological activity, 2) ricin, a toxin that is of broad interest, and 3) theophylline, an adenosine antagonist. Our designs are based on two approaches, the first method consisted of the use of two sets of AuNPs, each coated with a short oligonucleotide complementary to a different part of the sequence of the aptamer of interest. Hybridization of the DNA-coated particles (DNA-AuNPs) with the free aptamer produced aggregates, i.e. 3-part design. The second approach consisted of the use of only two sets of DNA-AuNPs, one coated with an aptamer that contains a thiol group in its 5′ end, and the second set of AuNPs coated with a sequence complementary to part of the aptamer. Hybridization of these two sets of particles produced aggregates, i.e. 2-part design. In both cases, the presence of the analyte promoted a change in the conformation of the aptamer, which caused the dehybridization of the complementary sequences. This conformational change of the aptamer upon binding of the analyte produced the dissociation of the nanoparticle aggregates, which is translated into a change in the color of the suspensions from blue to red. In this presentation, we will compare the advantages and disadvantages associated with a 3-part versus a 2-part nanoparticle-oligonucleotide reporting assay.
Our work presents results on human plasma protein adsorption onto a polyacrylic acid (PAA) film prepared via surface wave plasma (SWP) induced graft polymerization. The PAA film prepared in this manner is characterized by a carboxyl functional group and a constant contact angle in water of 35°. The adsorption kinetics of human plasma fibrinogen (HPF) and human serum albumin (HSA) proteins were measured by in-situ UV-ATR spectroscopy. The free energy of adsorption on PAA treated as well as untreated surfaces was −28 kJ M−1 and −22 kJ M−1 for HPF and HSA, respectively, regardless of surface chemistry. We determined that 14 μM and 6 μM HPF concentrations are enough to cover half of the maximum possible of surface coverage on silica and PAA film, respectively. HSA protein concentrations of 154 μM and 118 μM are enough to cover half of the maximum accessible surface of silica and PAA film, respectively. For surface treatment of implants with PAA polymer and protein, the necessary protein concentration for effective surface coverage should be known.
The idea of using nanocrystalline diamond (NCD) as a coating on orthopedic implants originates back to the last century since NCD possesses superior mechanical and tribological properties as well as chemical stability. However, it has only been within recent years that the interactions between NCD and osteoblasts (OB, bone forming cells) have been investigated. In this study, the impact of NCD surface topography on OB functions including proliferation (24 hrs to 48 hrs) and differentiation (7 to 21 days) was studied. NCD of varied grain sizes (from less than 100 nm to approximately 600 nm) were fabricated by microwave plasma enhanced chemical-vapor-deposition and characterized by scanning electron microscopy (SEM) and atomic force microscopy (AFM). Surface topography of the NCD changed dramatically as grain size grew. OB proliferation on these coatings was studied by SEM after incubation for 24 hrs and 48hrs, respectively. OB differentiation on diamond coatings after incubation from 1 to 3 weeks was investigated by alkaline phosphatase activity and calcium deposition. Results demonstrated that OB proliferation and differentiation were dependent on topography with NCD grain sizes less than 100 nm exhibiting the best OB responses. To explain this enhancement, OB filopodia protrusions on different NCD were observed by SEM and the results revealed that surface topography of NCD played a crucial role in OB filopodia extensions. In summary, these findings provided important design criteria for creating proper NCD surfaces for orthopedic coatings and also provided cues on promoting interactions between nanostructured surfaces and cell responses.
We herein report a facile, ‘green’ one- step synthesis of a series of monodispersed water-soluble selenide nanoparticles at room temperature. The capping ligands used include, cysteine, methionine, ascorbic acid and starch which function as agents of solubilisation, stabilization and conjugation sites for biomolecules. The synthetic approach involves the addition of an appropriate volume of selenide ion produced via the reduction of selenium powder in water to an aqueous solution containing the ligand- metal salt (MCl2 M = Zn or Cd). Optical spectroscopy shows that the particles are of high quality while the transmission electron microscopy (TEM) of the samples shows variation in shapes ranging from dots to rods of high and low aspect ratios.