Origin of enhancement in Raman scattering from Ag-dressed carbon-nanotube antennas: experiment and modelling.

The D- and G-band Raman signals from random arrays of vertically aligned, multi-walled carbon nanotubes are significantly enhanced (up to ∼14×) while the signal from the underlying Si substrate is simultaneously attenuated (up to ∼6×) when the nanotubes are dressed, either capped or coated, with Ag. These Ag-induced counter-changes originate with the difference in geometry of the nanotubes and planar Si substrate and contrast in the Ag depositions on the substrate (essentially thin film) and the nanotube (nano-particulate). The surface integral equation technique is used to perform detailed modelling of the electromagnetic response of the system in a computationally efficient manner. Within the modelling the overall antenna response of the Ag-dressed nanotubes is shown to underpin the main contribution to enhancement of the nanotube Raman signal with hot-spots between the Ag nanoparticles making a subsidiary contribution on account of their relatively weak penetration into the nanotube walls. Although additional hot-spot activity likely accounts for a shortfall in modelling relative to experiment it is nonetheless the case that the significant antenna-driven enhancement stands in marked contrast to the hot-spot dominated enhancement of the Raman spectra from molecules adsorbed on the same Ag-dressed structures. The Ag-dressing procedure for amplifying the nanotube Raman output not only allows for ready characterisation of individual nanotubes, but also evidences a small peak at ∼1150 cm-1 (not visible for the bare, undressed nanotube) which is suggested to be due to the presence of trans-polyacetylene in the structures.

Observation and coherent control of interface-induced electronic resonances in a field-effect transistor.

Electronic defect states at material interfaces provide highly deleterious sources of noise in solid-state nanostructures, and even a single trapped charge can qualitatively alter the properties of short one-dimensional nanowire field-effect transistors (FET) and quantum bit (qubit) devices. Understanding the dynamics of trapped charge is thus essential for future nanotechnologies, but their direct detection and manipulation is rather challenging. Here, a transistor-based set-up is used to create and probe individual electronic defect states that can be coherently driven with microwave (MW) pulses. Strikingly, we resolve a large number of very high quality (Q ∼ 1 × 105) resonances in the transistor current as a function of MW frequency and demonstrate both long decoherence times (∼1 µs-40 µs) and coherent control of the defect-induced dynamics. Efficiently characterizing over 800 individually addressable resonances across two separate defect-hosting materials, we propose that their properties are consistent with weakly driven two-level systems.

Electrochemical communication with the inside of cells using micro-patterned vertical carbon nanofibre electrodes.

With the rapidly increasing demands for ultrasensitive biodetection, the design and applications of new nano-scale materials for development of sensors based on optical and electrochemical transducers have attracted substantial interest. In particular, given the comparable sizes of nanomaterials and biomolecules, there exist plenty of opportunities to develop functional nanoprobes with biomolecules for highly sensitive and selective biosensing, shedding new light on cellular behaviour. Towards this aim, herein we interface cells with patterned nano-arrays of carbon nanofibers forming a nanosensor-cell construct. We show that such a construct is capable of electrochemically communicating with the intracellular environment.

Conjugated polyelectrolyte nano field emission adlayers.

Here we report on a straightforward and rapid means of enhancing the field electron emission performance of nascent vertically aligned multi-walled carbon nanotubes by introducing a polar zwitterionic conjugated polyelectrolyte adlayer at the vacuum-emitter interface. We attribute the observed 66% decrease in turn-on electric field to the augmented emitter micro-morphology and shifted surface band structure. The composite emitters can be optically modulated by exploiting the absorption cross-section of the solution cast adlayer, which increases the local carrier concentration which broadens the effective electrostatic shape of the emitter during optical excitation. Assessment via scanning anode field emission microscopy reveals a 25% improvement in DC time stability, a significant reduction in long-term hysteresis shift, and a threefold increase in bandwidth during pulsed mode operation.

A Systematic Review and Qualitative Analysis to Determine Quality Indicators forHealth Professions Education Blogs and Podcasts.

BACKGROUND: Historically, trainees in undergraduate and graduate health professions education have relied on secondary resources, such as textbooks and lectures, for core learning activities. Recently, blogs and podcasts have entered into mainstream usage, especially for residents and educators. These low-cost, widely available resources have many characteristics of disruptive innovations and, if they continue to improve in quality, have the potential to reinvigorate health professions education. One potential limitation of further growth in the use of these resources is the lack of information on their quality and effectiveness. OBJECTIVE: To identify quality indicators for secondary resources that are described in the literature, which might be applicable to blogs and podcasts. METHODS: Using a blended research methodology, we performed a systematic literature review using Google Scholar, MEDLINE, Embase, Web of Science, and ERIC to identify quality indicators for secondary resources. A qualitative analysis of these indicators resulted in the organization of this information into themes and subthemes. Expert focus groups were convened to triangulate these findings and ensure that no relevant quality indicators were missed. RESULTS: The literature search identified 4530 abstracts, and quality indicators were extracted from 157 articles. The qualitative analysis produced 3 themes (credibility, content, and design), 13 subthemes, and 151 quality indicators. CONCLUSIONS: The list of quality indicators resulting from our analysis can be used by stakeholders, including learners, educators, academic leaders, and blog/podcast producers. Further studies are being conducted, which will refine the list into a form that is more structured and stratified for use by these stakeholders.

Film bulk acoustic resonators integrated on arbitrary substrates using a polymer support layer.

The film bulk acoustic resonator (FBAR) is a widely-used MEMS device which can be used as a filter, or as a gravimetric sensor for biochemical or physical sensing. Current device architectures require the use of an acoustic mirror or a freestanding membrane and are fabricated as discrete components. A new architecture is demonstrated which permits fabrication and integration of FBARs on arbitrary substrates. Wave confinement is achieved by fabricating the resonator on a polyimide support layer. Results show when the polymer thickness is greater than a critical value, d, the FBARs have similar performance to devices using alternative architectures. For ZnO FBARs operating at 1.3-2.2 GHz, d is ~9 µm, and the devices have a Q-factor of 470, comparable to 493 for the membrane architecture devices. The polymer support makes the resonators insensitive to the underlying substrate. Yields over 95% have been achieved on roughened silicon, copper and glass.

Emergency Medicine and Critical Care Blogs and Podcasts: Establishing an International Consensus on Quality.

STUDY OBJECTIVE: This study identified the most important quality indicators for online educational resources such as blogs and podcasts. METHODS: A modified Delphi process that included 2 iterative surveys was used to build expert consensus on a previously defined list of 151 quality indicators divided into 3 themes: credibility, content, and design. Aggregate social media indicators were used to identify an expert population of editors from a defined list of emergency medicine and critical care blogs and podcasts. Survey 1 consisted of the quality indicators and a 7-point Likert scale. The mean score for each quality indicator was included in survey 2, which asked participants whether to "include" or "not include" each quality indicator. The cut point for consensus was defined at greater than 70% "include." RESULTS: Eighty-three percent (20/24) of bloggers and 90.9% (20/22) of podcasters completed survey 1 and 90% (18/20) of bloggers and podcasters completed survey 2. The 70% inclusion criteria were met by 44 and 80 quality indicators for bloggers and podcasters, respectively. Post hoc, a 90% cutoff was used to identify a list of 14 and 26 quality indicators for bloggers and podcasters, respectively. CONCLUSION: The relative importance of quality indicators for emergency medicine blogs and podcasts was determined. This will be helpful for resource producers trying to improve their blogs or podcasts and for learners, educators, and academic leaders assessing their quality. These results will inform broader validation studies and attempts to develop user-friendly assessment instruments for these resources.

Porous boron-doped diamond/carbon nanotube electrodes.

Nanostructuring boron-doped diamond (BDD) films increases their sensitivity and performance when used as electrodes in electrochemical environments. We have developed a method to produce such nanostructured, porous electrodes by depositing BDD thin film onto a densely packed "forest" of vertically aligned multiwalled carbon nanotubes (CNTs). The CNTs had previously been exposed to a suspension of nanodiamond in methanol causing them to clump together into "teepee" or "honeycomb" structures. These nanostructured CNT/BDD composite electrodes have been extensively characterized by scanning electron microscopy, Raman spectroscopy, cyclic voltammetry, and electrochemical impedance spectroscopy. Not only do these electrodes possess the excellent, well-known characteristics associated with BDD (large potential window, chemical inertness, low background levels), but also they have electroactive areas and double-layer capacitance values ∼450 times greater than those for the equivalent flat BDD electrodes.

Flexible surface acoustic wave resonators built on disposable plastic film for electronics and lab-on-a-chip applications.

Flexible electronics are a very promising technology for various applications. Several types of flexible devices have been developed, but there has been limited research on flexible electromechanical systems (MEMS). Surface acoustic wave (SAW) devices are not only an essential electronic device, but also are the building blocks for sensors and MEMS. Here we report a method of making flexible SAW devices using ZnO nanocrystals deposited on a cheap and bendable plastic film. The flexible SAW devices exhibit two wave modes - the Rayleigh and Lamb waves with resonant frequencies of 198.1 MHz and 447.0 MHz respectively, and signal amplitudes of 18 dB. The flexible devices have a high temperature coefficient of frequency, and are thus useful as sensitive temperature sensors. Moreover, strong acoustic streaming with a velocity of 3.4 cm/s and particle concentration using the SAW have been achieved, demonstrating the great potential for applications in electronics and MEMS.

Dual-mode thin film bulk acoustic wave resonators for parallel sensing of temperature and mass loading.

Thin film bulk acoustic wave resonator (FBAR) devices supporting simultaneously multiple resonance modes have been designed for gravimetric sensing. The mechanism for dual-mode generation within a single device has been discussed, and theoretical calculations based on finite element analysis allowed the fabrication of FBARs whose resonance modes have opposite reactions to temperature changes; one of the modes exhibiting a positive frequency shift for a rise of temperature whilst the other mode exhibits a negative shift. Both modes exhibit negative frequency shift for a mass load and hence by monitoring simultaneously both modes it is possible to distinguish whether a change in the resonance frequency is due to a mass load or temperature variation (or a combination of both), avoiding false positive/negative responses in gravimetric sensing without the need of additional reference devices or complex electronics.

Microfluidics based on ZnO/nanocrystalline diamond surface acoustic wave devices.

Surface acoustic wave (SAW) devices with 64 µm wavelength were fabricated on a zinc oxide (ZnO) film deposited on top of an ultra-smooth nanocrystalline diamond (UNCD) layer. The smooth surface of the UNCD film allowed the growth of the ZnO film with excellent c-axis orientation and low surface roughness, suitable for SAW fabrication, and could restrain the wave from significantly dissipating into the substrate. The frequency response of the fabricated devices was characterized and a Rayleigh mode was observed at ∼65.4 MHz. This mode was utilised to demonstrate that the ZnO/UNCD SAW device can be successfully used for microfluidic applications. Streaming, pumping, and jetting using microdroplets of 0.5 and 20 µl were achieved and characterized under different powers applied to the SAW device, focusing more on the jetting behaviors induced by the ZnO SAW.

Emergency medicine ultrasonography in rural communities.

INTRODUCTION: The Canadian Association of Emergency Physicians (CAEP) published a position statement in 2006 encouraging immediate access to emergency medicine ultrasonography (EMUS) 24 hours a day, 7 days a week. However, barriers to advanced imaging care still exist in many rural hospitals. Our study investigated the current availability of EMUS in rural communities and physicians' ability to use this technology. METHODS: A literature review and interviews with rural physicians were conducted in the summer of 2010 to design a questionnaire focusing on EMUS. The survey was then sent electronically or via regular mail in November 2010 to all Ontario physicians self-identified as "rural." Descriptive statistics and the Fisher exact test were used to analyze the data. RESULTS: A total of 207 rural physicians responded to the survey (response rate 28.6%). Of the respondents, 70.9% were male, median age was 49 years and median year of graduation was 1988. The respondents had been in practice for a median of 20 years and had been in their present community for a median of 15 years. More than two-thirds of physicians (69.5%) practised in communities with populations of less than 10 000. Nearly three-quarters (72.6%) worked in a rural emergency department (ED). Almost all (96.9%) reported having access to ultrasonography in the hospital. However, only 60.6% had access to ultrasonography in the ED. Less than half (44.4%) knew how to perform ultrasonography, with 77.3% citing lack of training. Of those using EMUS, 32.5% were using it at least once per shift. The most common reason to use EMUS was to rule out abdominal aortic aneurysm (58.3%). Most respondents (71.5%) agreed or strongly agreed that EMUS is a skill that all rural ED physicians should have. CONCLUSION: Patients in many rural EDs do not have immediate access to EMUS, as advocated by CAEP. This gap in care needs to be addressed to ensure that all patients, no matter where they live, have access to this proven imaging modality.

Diagnostic approach to pulmonary embolism in a rural emergency department.

INTRODUCTION: Pulmonary embolism (PE) is a serious condition with mortality estimates of up to 10%. We sought to investigate the diagnosis of PE, time to access imaging and diagnostic utility of each modality in a rural emergency department (Ed). METHODS: We completed a retrospective chart review to determine the investigations performed and treatments initiated in the management of suspected PE in a rural hospital. RESULTS: A total of 47 charts from a 5-year period were reviewed. Of these, 83.0% indicated a D-dimer test was ordered, and 31.9% and 40.4% indicated either ventilation-perfusion (V/Q) or computed tomography (CT) were ordered during the ED visit. Computed tomography diagnosed 11 of the 12 instances of confirmed PE. Mean time to patients undergoing V/Q or CT was 1.58 and 1.59 days, respectively. Low-molecular-weight heparin was started in 83.0% of patients. CONCLUSION: In this ED there may be over reliance on the D-dimer test, irrespective of Wells score. Access to V/Q and CT were similar to that of an urban centre. Empiric anticoagulation was started in most patients.

Accuracy of the Broselow tape in estimating the weight of First Nations children.

INTRODUCTION: During resuscitation, the Broselow tape (BT) is the standard method of estimating pediatric weight based on body length. The First Nations population has a higher prevalence of obesity and experiences more injury than the non-First Nations population. The prevalence of obesity has raised the concern that the BT may not accurately estimate weight in this population. The purpose of this study was to validate the BT in 8 First Nations communities. METHODS: We performed a search of the electronic medical records of 2 community health centres that serve 8 local First Nations communities. We searched for the most recent clinic visit during which height and weight had been recorded in the records of patients less than 10 years of age with a postal code indicating residence in a First Nations community. The patients' actual weight was compared with their BT weight estimates using the Bland-Altman method. The Spearman coefficient of rank and percentage error was also calculated. RESULTS: A total of 243 children were included in the study (119 girls, 124 boys). The mean age was 33.3 months (95% confidence interval [CI] 29.7 to 36.9), mean height was 91.8 cm (95% CI 89.0 to 94.6), mean weight was 16.2 kg (95% CI 15.0 to 17.3)and mean BT weight was 14.0 kg (95% CI 13.1 to 14.8). The Bland-Altman percent difference was 11.9% (95% CI -17.3% to 41.1%). The Spearman coefficient of rank correlation was 0.963 (p < 0.001). The BT had a percentage error greater than 10% error 51.8% of the time, with 49.4% being underestimations. CONCLUSION: The BT was often not accurate at estimating the weight of children in 8 First Nations communities; it underestimated their weight almost half of the time.

Combined antenna and localized plasmon resonance in Raman scattering from random arrays of silver-coated, vertically aligned multiwalled carbon nanotubes.

The electric field enhancement associated with detailed structure within novel optical antenna nanostructures is modeled using the surface integral equation technique in the context of surface-enhanced Raman scattering (SERS). The antennae comprise random arrays of vertically aligned, multiwalled carbon nanotubes dressed with highly granular Ag. Different types of "hot-spot" underpinning the SERS are identified, but contrasting characteristics are revealed. Those at the outer edges of the Ag grains are antenna driven with field enhancement amplified in antenna antinodes while intergrain hotspots are largely independent of antenna activity. Hot-spots between the tops of antennae leaning towards each other also appear to benefit from antenna amplification.