Evidence-based surgery for laparoscopic appendectomy: A stepwise systematic review.

INTRODUCTION: Appendectomy is a common emergency surgery performed globally. Despite the frequency of laparoscopic appendectomy, consensus does not exist on the best way to perform each procedural step. We identified literature on key intraoperative steps to inform best technical practice during laparoscopic appendectomy. METHODS: Research questions were framed using the population, indication, comparison, outcome (PICO) format for 6 key operative steps of laparoscopic appendectomy: abdominal entry, placement of laparoscopic ports, division of mesoappendix, division of appendix, removal of appendix, and fascial closure. These questions were used to build literature queries in PubMed, EMBASE, and the Cochrane Library databases. Evidence quality and certainty was assessed using Grading of Recommendations, Assessment, Development, and Evaluation (GRADE) definitions. RESULTS: Recommendations were rendered for 6 PICO questions based on 28 full length articles. Low quality evidence favors direct trocar insertion for abdominal entry and establishment of pneumoperitoneum. Single port appendectomy results in improved cosmesis with unclear clinical implications. There was insufficient data to determine the optimal method of appendiceal stump closure, but use of a specimen extraction bag reduces rates of superficial surgical site infection and intra-abdominal abscess. Port sites made with radially dilating trocars are less likely to necessitate closure and are less likely to result in port site hernia. When port sites are closed, a closure device should be used. CONCLUSION: Key operative steps of laparoscopic appendectomy have sufficient data to encourage standardized practice.

Application of medical cannabis in unstable angina and coronary artery disease: A case report.

RATIONALE: First discovered in 1990, the endocannabinoid system (ECS) was initially shown to have an intimate relationship with central areas of the nervous system associated with pain, reward, and motivation. Recently, however, the ECS has been extensively implicated in the cardiovascular system with contractility, heart rate, blood pressure, and vasodilation. Emerging data demonstrate modulation of the ECS plays an essential role in cardio metabolic risk, atherosclerosis, and can even limit damage to cardiomyocytes during ischemic events. PATIENT CONCERNS: This case describes a 63-year-old man who presented to a primary care physician for a medical cannabis (MC) consult due to unstable angina (UA) not relieved by morphine or cardiac medications; having failed all first- and second-line polypharmaceutical therapies. The patient reported frequent, unprovoked, angina and exertional dyspnea. DIAGNOSIS: Having a complex cardiac history, the patient first presented 22 years ago after a suspected myocardial infarction. He re-presented in 2010 and underwent stent placement at that time for inoperable triple-vessel coronary artery disease (CAD) which was identified via percutaneous transluminal coronary angioplasty. UA developed on follow-up and, despite medical management over the past 6 years, became progressively debilitating. INTERVENTIONS AND OUTCOMES: In conjunction with his standard cardiac care, patient had a gradual lessening of UA-related pain, including frequency and character, after using an edible form of MC (1:1 cannabidiol:Δ9-tetrahydrocannabinol). Following continued treatment, he ceased long-term morphine treatment and described the pain as no longer crippling. As demonstrated by his exercise tolerance tests, the patient experienced an improved functional capacity and reported an increase in his daily functioning, and overall activity. LESSONS: This case uniquely highlights MC in possibly reducing the character, quality, and frequency of UA, whereas concordantly improving functional cardiac capacity in a patient with CAD. Additional case reports are necessary to verify this.

Aluminum Precursor Interactions with Alkali Compounds in Thermal Atomic Layer Etching and Deposition Processes.

Surface fluorination and volatilization using hydrogen fluoride and trimethyaluminum (TMA) is a useful approach to the thermal atomic layer etching of Al2O3. We have previously shown that significant enhancement of the TMA etching effect occurs when performed in the presence of lithium fluoride chamber-conditioning films. Now, we extend this enhanced approach to other alkali halide compounds including NaCl, KBr, and CsI. These materials are shown to have varying capacities for the efficient removal of AlF3 and ultimately lead to larger effective Al2O3 etch rates at a given substrate temperature. The most effective compounds allow for continuous etching of Al2O3 at substrate temperatures lower than 150 °C, which can be a valuable route for processing temperature-sensitive substrates and for improving the selectivity of the etch over other materials. The strong interaction between TMA and alkali halide materials also results in material-selective thin-film deposition at these reduced substrate temperatures. We discuss possible mechanisms of this etching enhancement and prospects for extending this approach to other material systems. The consequences of using TMA as an ALD and ALE precursor are discussed in the context of interface engineering for alkali-containing substrates such as lithium battery materials.

Extension Educators and Volunteer Leaders: Evaluation of Fitness Outcomes Among Participants in Community Strength Training Classes.

Volunteer-led strength training classes can expand access, improve exercise adherence, and enhance intervention sustainability for older adults. This study compared participant functional fitness outcomes between volunteer-led and Extension educator-led StrongWomen strength training groups in community settings. Change scores for participants (n = 317) were calculated for six Senior Fitness Test (SFT) measures. A non-parametric analysis of independent samples to determine SFT score differences between participant groups (educator-led and volunteer-led) showed no significant differences. Volunteers and professionals, like Extension educators, may be similarly effective in conducting community-based strength training classes resulting in improved functional fitness outcomes. We offer recommendations for organizations seeking to adopt similar approaches.

Silver Nanofilament Formation Dynamics in a Polymer-Ionic Liquid Thin Film by Direct-Write.

Silver nanofilament formation dynamics are reported for an ionic liquid (IL)-filled solid polymer electrolyte prepared by a direct-write process using a conductive atomic force microscope (C-AFM). Filaments are electrochemically formed at hundreds of xy locations on a ~40 nm thick polymer electrolyte, polyethylene glycol diacrylate (PEGDA)/[BMIM]PF6. Although the formation time generally decreases with increasing bias from 0.7 to 3.0 V, an unexpected non-monotonic maximum is observed ~ 2.0 V. At voltages approaching this region of inverted kinetics, IL electric double layers (EDLs) becomes detectable; thus, the increased nanofilament formation time can be attributed to electric field screening which hinders silver electro-migration and deposition. Scanning electron microscopy confirms that nanofilaments formed in this inverted region have significantly more lateral and diffuse features. Time-dependent formation currents reveal two types of nanofilament growth dynamics: abrupt, where the resistance decreases sharply over as little as a few ms, and gradual where it decreases more slowly over hundreds of ms. Whether the resistance change is abrupt or gradual depends on the extent to which the EDL screens the electric field. Tuning the formation time and growth dynamics using an IL opens the range of accessible resistance states, which is useful for neuromorphic applications.

Tunable optical metamaterial-based sensors enabled by closed bipolar electrochemistry.

Enabled by the proliferation of nanoscale fabrication techniques required to create spatially-repeating, sub-wavelength structures to manipulate the behavior of visible-wavelength radiation, optical metamaterials are of increasing interest. Here we develop and characterize a chemical sensing approach based on electrochemical tuning of the optical response function of large-area, inexpensive nanoaperture metamaterials at visible and near-IR wavelengths. Nanosphere lithography is used to create an ordered array of sub-wavelength apertures in a Au film. The spacing of these apertures is established during fabrication, based on the size of the polystyrene nanospheres. Tunable shifts in the transmission spectrum can be produced post-fabrication by electrodeposition of a dissimilar metal, Ag, using the nanoaperture film as one electrode in a 2-electrode closed bipolar electrochemical (CBE) cell, altering hole size, film thickness, and film composition while maintaining hole spacing dictated by the original pattern. Optical transmission spectra acquired under galvanostatic conditions can be expressed as a linear combination of the initial and final (saturated) spectra, and the resulting response function exhibits a sigmoidal response with respect to the amount of charge (or metal) deposited. This architecture is then used to perform optical coulometry of model analytes in a CBE-based analyte-reporter dual cell device, thus expanding the capability of CBE-based sensors. Increasing the exposed electrode area of the analyte cell increases the response of the device, while modifying the circuit resistance alters the balance between sensitivity and dynamic range. These tunable nanoaperture metamaterials exhibit enhanced sensitivity compared to CBE electrochromic reporter cells to the µM to nM concentration range, suggesting further avenues for development of CBE-based chemical sensors as well as application to inexpensive, point-of-care diagnostic devices.

Nanopore-Templated Silver Nanoparticle Arrays Photopolymerized in Zero-Mode Waveguides.

In situ fabrication of nanostructures within a solid-polymer electrolyte confined to subwavelength-diameter nanoapertures is a promising approach for producing nanomaterials for nanophotonic and chemical sensing applications. The solid-polymer electrolyte can be patterned by lithographic photopolymerization of poly(ethylene glycol) diacrylate (PEGDA)-based silver cation (Ag+)-containing polyelectrolyte. Here, we present a new method for fabricating nanopore-templated Ag nanoparticle (AgNP) arrays by in situ photopolymerization using a zero-mode waveguide (ZMW) array to simultaneously template embedded AgNPs and control the spatial distribution of the optical field used for photopolymerization. The approach starts with an array of nanopores fabricated by sequential layer-by-layer deposition and focused ion beam milling. These structures have an optically transparent bottom, allowing access of the optical radiation to the attoliter-volume ZMW region to photopolymerize a PEGDA monomer solution containing AgNPs and Ag+. The electric field intensity distribution is calculated for various ZMW optical cladding layer thicknesses using finite-element simulations, closely following the light-blocking efficiency of the optical cladding layer. The fidelity of the polyelectrolyte nanopillar pattern was optimized with respect to experimental conditions, including the presence or absence of Ag+ and AgNPs and the concentrations of PEGDA and Ag+. The self-templated approach for photopatterning high-resolution photolabile polyelectrolyte nanostructures directly within a ZMW array could lead to a new class of metamaterials formed by embedding metal nanoparticles within a dielectric in a well-defined spatial array.

Capture of Single Silver Nanoparticles in Nanopore Arrays Detected by Simultaneous Amperometry and Surface-Enhanced Raman Scattering.

The attoliter volumes and confinement abilities of zero-dimensional nanopore-electrode arrays (NEAs) hold considerable promise for examining the behavior of single nanoparticles. In this work, we use surface-enhanced Raman scattering (SERS) in tandem with amperometry in order to monitor single Ag Raman-sentinel nanoparticles transported to and captured in single nanopores. To that end, highly ordered solid-state NEAs were fabricated to contain periodic arrays of nanopores, each housing a single recessed Au-ring electrode. These were used to electrostatically capture and trap single silver nanoparticles (AgNPs) functionalized with the electrochemically stable Raman reporter, 1,4-bis(2-methylstyryl)benzene (bis-MSB). Transport and capture of the bis-MSB-tagged AgNPs in the nanopores was followed by simultaneous amperometry and SERS signals characteristic of AgNP oxidation and enhanced Raman scattering by bis-MSB at silver-gold hot spots, respectively. The frequency and magnitude of oxidation-current spikes increased with stepwise increases in DC voltage, and characteristic bis-MSB SERS spectra were observed. Under AC excitation, on the other hand, two distinctly different types of SERS signals were observed, independent of frequency and amplitude: (1) strong, transient (<10 s) spectra and (2) slow (>100 s) monotonically diminishing spectra. We hypothesize that the former behavior results from AgNP aggregates, whereas the latter occurs as a result of multiple incomplete AgNP-oxidation events in succession. These results show that attoliter-volume NEAs are competent for acquiring concurrent SERS spectra and for amperometry of single nanoparticles and that together these measurements can illuminate the collision dynamics of nanoparticles in confined environments.

Direct-Write Formation and Dissolution of Silver Nanofilaments in Ionic Liquid-Polymer Electrolyte Composites.

Materials with reconfigurable optical properties are candidates for applications such as optical cloaking and wearable sensors. One approach to fabricate these materials is to use external fields to form and dissolve nanoscale conductive channels in well-defined locations within a polymer. In this study, conductive atomic force microscopy is used to electrochemically form and dissolve nanoscale conductive filaments at spatially distinct points in a polyethylene glycol diacrylate (PEGDA)-based electrolyte blended with varying amounts of ionic liquid (IL) and silver salt. The fastest filament formation and dissolution times are detected in a PEGDA/IL composite that has the largest modulus (several GPa) and the highest polymer crystal fraction. This is unexpected because filament formation and dissolution events are controlled by ion transport, which is typically faster within amorphous regions where polymer mobility is high. Filament kinetics in primarily amorphous and crystalline regions are measured, and two different mechanisms are observed. The formation time distributions show a power-law dependence in the crystalline regions, attributable to hopping-based ion transport, while amorphous regions show a normal distribution. The results indicate that the timescale of filament formation/dissolution is determined by local structure, and suggest that structure could be used to tune the optical properties of the film.

The Relationship Between Perceptions of Emergency Preparedness, Disaster Experience, Health-Care Provider Education, and Emergency Preparedness Levels.

Objective The purpose of this study was to assess the self-reported level of individual emergency preparedness, the dependent variable, of people who attended a community health-related fair. The study's independent variables included demographic characteristics, perceptions of preparedness, previous disaster experience, and the presence of a medical condition and were used to examine the variability in self-reported emergency preparedness levels. Methods Data came from attendees at two community health-related fairs. Multivariate analysis on 188 participants was performed. A model predicting preparedness levels with demographic variables was constructed; successive models were built adding perceptions of preparedness, personal experiences with disasters, and presence of a medical condition. Results Preparedness levels varied little across sociodemographic dimensions explaining virtually no variance in overall preparedness. Subsequent models adding perceptions of preparedness and personal experiences significantly increased the explained variance to 40%. Of participants who reported a medical condition, the model including discussions about emergency preparedness with health-care providers explained 67% of the variance in overall preparedness levels. Conclusion The strong, positive relationship between the health-care provider and preparedness levels indicates a pathway for effecting change in preparedness levels and ultimately community health after an emergency. The inclusion of such education at community events should be considered. Research agendas should include providing evidence for the contents of disaster supply kits.

Stories after disaster survival: Preparing, heeding warnings, and self-reliance.

OBJECTIVE: The purpose of the study was to examine the content of stories told by people personally impacted by disasters. DESIGN: Semistructured, qualitative interviews. SETTING: Northwest part of a mid-south state. PARTICIPANTS: Fourteen disaster survivors who were recruited through their attendance at an emergency preparedness-related fair. MAIN OUTCOME MEASURES: Interview schedule based on previous research using the family resilience framework. RESULTS: Three themes emerged: prior emergency preparation, heeding warnings of impending disaster, and rural self-reliance. CONCLUSIONS: Participants had made prior emergency preparedness plans, but their personal experiences led to them adjusting their plans, or making more relevant plans for future disasters. Participants expressed the importance of sharing their experiences with family and community members, expressing hope that others would learn, vicariously rather than first-hand, from their experiences.

Voltage-Gated Nanoparticle Transport and Collisions in Attoliter-Volume Nanopore Electrode Arrays.

Single nanoparticle analysis can reveal how particle-to-particle heterogeneity affects ensemble properties derived from traditional bulk measurements. High-bandwidth, low noise electrochemical measurements are needed to examine the fast heterogeneous electron-transfer behavior of single nanoparticles with sufficient fidelity to resolve the behavior of individual nanoparticles. Herein, nanopore electrode arrays (NEAs) are fabricated in which each pore supports two vertically spaced, individually addressable electrodes. The top ring electrode serves as a particle gate to control the transport of silver nanoparticles (AgNPs) within individual attoliter volume NEAs nanopores, as shown by redox collisions of AgNPs collisions at the bottom disk electrode. The AgNP-nanoporeis system has wide-ranging technological applications as well as fundamental interest, since the transport of AgNPs within the NEA mimics the transport of ions through cell membranes via voltage-gated ion channels. A voltage threshold is observed above which AgNPs are able to access the bottom electrode of the NEAs, i.e., a minimum potential at the gate electrode is required to switch between few and many observed collision events on the collector electrode. It is further shown that this threshold voltage is strongly dependent on the applied voltage at both electrodes as well as the size of AgNPs, as shown both experimentally and through finite-element modeling. Overall, this study provides a precise method of monitoring nanoparticle transport and in situ redox reactions within nanoconfined spaces at the single particle level.

Electrochemical Zero-Mode Waveguide Studies of Single Enzyme Reactions.

Because electron transfer reactions are fundamental to life processes, such as respiration, vision, and energy catabolism, it is critically important to understand the relationship between functional states of individual redox enzymes and the macroscopically observed phenotype, which results from averaging over all copies of the same enzyme. To address this problem, we have developed a new technology, based on a bifunctional nanoelectrochemical-nanophotonic architecture - the electrochemical zero mode waveguide (E-ZMW) - that can couple biological electron transfer reactions to luminescence, making it possible to observe single electron transfer events in redox enzymes. Here we describe E-ZMW architectures capable of supporting potential-controlled redox reactions with single copies of the oxidoreductase enzyme, glutathione reductase, GR, and extend these capabilities to electron transfer events where reactive oxygen species are synthesized within the ~100 zL volume of the nanopore.

Zero-Mode Waveguide Nanophotonic Structures for Single Molecule Characterization.

Single-molecule characterization has become a crucial research tool in the chemical and life sciences, but limitations, such as limited concentration range, inability to control molecular distributions in space, and intrinsic phenomena, such as photobleaching, present significant challenges. Recent developments in non-classical optics and nanophotonics offer promising routes to mitigating these restrictions, such that even low affinity (K D ~ mM) biomolecular interactions can be studied. Here we introduce and review specific nanophotonic devices used to support single molecule studies. Optical nanostructures, such as zero-mode waveguides (ZMWs), are usually fabricated in thin gold or aluminum films and serve to confine the observation volume of optical microspectroscopy to attoliter to zeptoliter volumes. These simple nanostructures allow individual molecules to be isolated for optical and electrochemical analysis, even when the molecules of interest are present at high concentration (µM - mM) in bulk solution. Arrays of ZMWs may be combined with optical probes such as single molecule fluorescence, single molecule fluorescence resonance energy transfer (smFRET), and fluorescence correlation spectroscopy (FCS) for distributed analysis of large numbers of single-molecule reactions or binding events in parallel. Furthermore, ZMWs may be used as multifunctional devices, for example by combining optical and electrochemical functions in a single discrete architecture to achieve electrochemical ZMWs (E-ZMW). In this review, we will describe the optical properties, fabrication, and applications of ZMWs for single-molecule studies, as well as the integration of ZMWs into systems for chemical and biochemical analysis.

Single-molecule spectroelectrochemical cross-correlation during redox cycling in recessed dual ring electrode zero-mode waveguides.

The ability of zero-mode waveguides (ZMW) to guide light into subwavelength-diameter nanoapertures has been exploited for studying electron transfer dynamics in zeptoliter-volume nanopores under single-molecule occupancy conditions. In this work, we report the spectroelectrochemical detection of individual molecules of the redox-active, fluorogenic molecule flavin mononucleotide (FMN) freely diffusing in solution. Our approach is based on an array of nanopore-confined recessed dual ring electrodes, wherein repeated reduction and oxidation of a single molecule at two closely spaced annular working electrodes yields amplified electrochemical signals. We have articulated these structures with an optically transparent bottom, so that the nanopores are bifunctional, exhibiting both nanophotonic and nanoelectrochemical behaviors allowing the coupling between electron transfer and fluorescence dynamics to be studied under redox cycling conditions. We also investigated the electric field intensity in electrochemical ZMWs (E-ZMW) through finite-element simulations, and the amplification of fluorescence by redox cycling agrees well with predictions based on optical confinement effects inside the E-ZMW. Proof-of-principle experiments are conducted showing that electrochemical and fluorescence signals may be correlated to reveal single molecule fluctuations in the array population. Cross-correlation of single molecule fluctuations in amperometric response and single photon emission provides unequivocal evidence of single molecule sensitivity.

Addressable Direct-Write Nanoscale Filament Formation and Dissolution by Nanoparticle-Mediated Bipolar Electrochemistry.

Nanoscale conductive filaments, usually associated with resistive memory or memristor technology, may also be used for chemical sensing and nanophotonic applications; however, realistic implementation of the technology requires precise knowledge of the conditions that control the formation and dissolution of filaments. Here we describe and characterize an addressable direct-write nanoelectrochemical approach to achieve repeatable formation/dissolution of Ag filaments across a ∼100 nm poly(ethylene oxide) (PEO) film containing either Ag+ alone or Ag+ together with 50 nm Ag-nanoparticles acting as bipolar electrodes. Using a conductive AFM tip, formation occurs when the PEO film is subjected to a forward bias, and dissolution occurs under reverse bias. Formation-dissolution kinetics were studied for three film compositions: Ag|PEO-Ag+, Ag|poly(ethylene glycol) monolayer-PEO-Ag+, and Ag|poly(ethylene glycol) monolayer-PEO-Ag+/Ag-nanoparticle. Statistical analysis shows that the distribution of formation times exhibits Gaussian behavior, and the fastest average initial formation time occurs for the Ag|PEO-Ag+ system. In contrast, formation in the presence of Ag nanoparticles likely proceeds by a noncontact bipolar electrochemical mechanism, exhibiting the slowest initial filament formation. Dissolution times are log-normal for all three systems, and repeated reformation of filaments from previously formed structures is characterized by rapid regrowth. The direct-write bipolar electrochemical deposition/dissolution strategy developed here presents an approach to reconfigurable, noncontact in situ wiring of nanoparticle arrays-thereby enabling applications where actively controlled connectivity of nanoparticle arrays is used to manipulate nanoelectronic and nanophotonic behavior. The system further allows for facile manipulation of experimental conditions while simultaneously characterizing surface conditions and filament formation/dissolution kinetics.

Objective biometric measurements of calf-fed Holstein steers fed in confinement.

Understanding the maximum slaughter size for calf-fed Holstein steers based on hip-height has become a contemporary issue in the beef processing industry. Increased carcass size, in terms of both weight and length, has outpaced the ability of some abattoirs to handle the larger animals. Moreover, some abattoirs have begun rejecting animals that exceed 147.3 cm (58 inches) at the hip, creating a challenge for Holstein cattle feeders. The objective of this study was to quantify the skeletal growth rate of calf-fed Holstein steers fed in confinement. Hip-height of calf-fed Holstein steers ( ≤ 135) was measured every 28 d from 226 to 422 d on feed. Hip-height was a dependent variable modeled via linear regression procedures utilizing days of age and BW as independent variables. Additionally, logistic regression was used to estimate the probability of a steer exceeding a hip-height of 147.3 cm (58 inches) from independent variables of days of age and BW. The linear relationship of BW to hip-height had an adjusted value of 0.7112 (Hip-height, cm = [0.0593 × BW, kg] + 109.00) and on average the calf-fed Holstein steers grew 1.0 cm for each 16.9 kg of BW gain during the finishing phase. The 10%, 50%, and 90% probability of a steer exceeding 147.3 cm (58 inches) of hip-height was achieved at 563, 653, and 743 kg of BW, respectively. The linear relationship of days of age to hip-height had an adjusted value of 0.6687 (Hip-height, cm = [0.0937 × days of age] + 104.4) and the calf-fed Holstein steers grew 1.0 cm for each 10.7 d of age during the finishing phase. The 10%, 50%, and 90% probability of a steer exceeding 147.3 cm (58 inches) of hip-height was estimated to occur at 408, 459, and 510 d of age, respectively. Knowledge of Holstein steer growth rate in relation to BW and age may allow for more accurate sorting to prevent oversized cattle arriving at the abattoir and subsequent discounts or being rejected for slaughter.

Microchannel Voltammetry in the Presence of Large External Voltages and Electric Fields.

The ability to perform electrochemistry in the presence of large voltages and electric field magnitudes without concern for the local potential has many possible applications in micro/nanofluidic assays and in capillary electrophoresis. Traditionally, electrochemistry in the presence of significant external electric fields has been dominated by end-channel detection for capillary and microchip electrophoresis detection. We describe novel instrumentation for potentiostatically controlled voltammetry that can be applied in the presence of high external voltages and electric fields. Cyclic voltammetry is demonstrated without significant shifts in the half-wave potential at working electrodes at local potentials of up to ∼1500 V and field strengths of up to 3000 V/cm, using a standard Ag/AgCl reference electrode.

Single occupancy spectroelectrochemistry of freely diffusing flavin mononucleotide in zero-dimensional nanophotonic structures.

Zero-mode waveguides (ZMW) have the potential to be powerful confinement tools for studying electron transfer dynamics at single molecule occupancy conditions. Flavin mononucleotide contains an isoalloxazine chromophore, which is fluorescent in the oxidized state (FMN) while the reduced state (FMNH2) exhibits dramatically lower light emission, i.e. a dark-state. This allows fluorescence emission to report the redox state of single FMN molecules, an observation that has been used previously to study single electron transfer events in surface-immobilized flavins and flavoenzymes, e.g. sarcosine oxidase, by direct wide-field imaging of ZMW arrays. Single molecule electron transfer dynamics have now been extended to the study of freely diffusing molecules using fluorescence measurements of Au ZMWs under single occupancy conditions. The Au in the ZMW serves both as an optical cladding layer and as the working electrode for potential control, thereby accessing single molecule electron transfer dynamics at µM concentrations. Consistent with expectations, the probability of observing single reduced molecules increases as the potential is scanned negative, E(appl) < E(eq), and the probability of observing emitting oxidized molecules increases at E(appl) > E(eq). Different single molecules exhibit different electron transfer properties as reflected in the position of E(eq) and the distribution of E(eq) among a population of FMN molecules. Two types of actively-controlled electroluminescence experiments were used: chronofluorometry experiments, in which the potential is alternately stepped between oxidizing and reducing potentials, and cyclic potential sweep fluorescence experiments, analogous to cyclic voltammetry, these latter experiments exhibiting a dramatic scan rate dependence with the slowest scan rates showing distinct intermediate states that are stable over a range of potentials. These states are assigned to flavosemiquinone species that are stabilized in the special environment of the ZMW nanopore.

Comparison of tibialis anterior muscle electromyography, ankle angle, and velocity when individuals post stroke walk with different orthoses.

BACKGROUND: Ankle-foot orthoses (AFO) have been used to improve the gait of individuals post stroke, but their use has come into question secondary to increased understanding of motor re-learning. OBJECTIVES: The purpose of this study was to determine if there is a change in tibialis anterior muscle electromyography, ankle angle, or gait velocity when individuals post stroke walk with a posterior leaf-spring AFO (PLAFO) or a dynamic ankle orthosis (DAO). STUDY DESIGN: Repeated measures. METHODS: Fifteen participants post stroke walked without an orthosis, with a PLAFO, and with a DAO. Data were gathered using electromyography, force plates, and three-dimensional motion analysis cameras. A repeated measures ANOVA was used to test for statistical significance (p ≤ 0.05). RESULTS: Participants exhibited significantly less tibialis anterior muscle electromyography during the swing phase of gait with use of a DAO (p < 0.001). No change in velocity or ankle angle was exhibited with use of either orthosis. CONCLUSIONS: The results support therapists' notions that bracing can lead to a decline in tibialis anterior muscle activity during the swing phase of gait. The results also showed no improvement in gait velocity when either orthosis was used by participants who could walk without an orthosis.