Surface-Roughened Graphene Oxide Microfibers Enhance Electrochemical Reversibility.

Here, we provide an optimized method for fabricating surface-roughened graphene oxide disk microelectrodes (GFMEs) with enhanced defect density to generate a more suitable electrode surface for dopamine detection with fast-scan cyclic voltammetry (FSCV). FSCV detection, which is often influenced by adsorption-based surface interactions, is commonly impacted by the chemical and geometric structure of the electrode's surface, and graphene oxide is a tunable carbon-based nanomaterial capable of enhancing these two key characteristics. Synthesized GFMEs possess exquisite electronic and mechanical properties. We have optimized an applied inert argon (Ar) plasma treatment to increase defect density, with minimal changes in chemical functionality, for enhanced surface crevices to momentarily trap dopamine during detection. Optimal Ar plasma treatment (100 sccm, 60 s, 100 W) generates crevice depths of 33.4 ± 2.3 nm with high edge plane character enhancing dopamine interfacial interactions. Increases in GFME surface roughness improve electron transfer rates and limit diffusional rates out of the crevices to create nearly reversible dopamine electrochemical redox interactions. The utility of surface-roughened disk GFMEs provides comparable detection sensitivities to traditional cylindrical carbon fiber microelectrodes while improving temporal resolution ten-fold with amplified oxidation current due to dopamine cyclization. Overall, surface-roughened GFMEs enable improved adsorption interactions, momentary trapping, and current amplification, expanding the utility of GO microelectrodes for FSCV detection.

Waste Coffee Ground-Derived Porous Carbon for Neurochemical Detection.

We present an optimized synthetic method for repurposing coffee waste to create controllable, uniform porous carbon frameworks for biosensor applications to enhance neurotransmitter detection with fast-scan cyclic voltammetry. Harnessing porous carbon structures from biowastes is a common practice for low-cost energy storage applications; however, repurposing biowastes for biosensing applications has not been explored. Waste coffee ground-derived porous carbon was synthesized by chemical activation to form multivoid, hierarchical porous carbon, and this synthesis was specifically optimized for porous uniformity and electrochemical detection. These materials, when modified on carbon-fiber microelectrodes, exhibited high surface roughness and pore distribution, which contributed to significant improvements in electrochemical reversibility and oxidative current for dopamine (3.5 ± 0.4-fold) and other neurochemicals. Capacitive current increases were small, showing evidence of small increases in electroactive surface area. Local trapping of dopamine within the pores led to improved electrochemical reversibility and frequency-independent behavior. Overall, we demonstrate an optimized biowaste-derived porous carbon synthesis for neurotransmitter detection for the first time and show material utility for viable neurotransmitter detection within a tissue matrix. This work supports the notion that controlled surface nanogeometries play a key role in electrochemical detection.

The yaq project: Standardized software enabling flexible instrumentation.

Modern instrumentation development often involves the incorporation of many dissimilar hardware peripherals into a single unified instrument. The increasing availability of modular hardware has brought greater instrument complexity to small research groups. This complexity stretches the capability of traditional, monolithic orchestration software. In many cases, a lack of software flexibility leads creative researchers to feel frustrated, unable to perform experiments they envision. Herein, we describe Yet Another acQuisition (yaq), a software project defining a new standardized way of communicating with diverse hardware peripherals. yaq encourages a highly modular approach to experimental software development that is well suited to address the experimental flexibility needs of complex instruments. yaq is designed to overcome hardware communication barriers that challenge typical experimental software. A large number of hardware peripherals are already supported, with tooling available to expand support. The yaq standard enables collaboration among multiple research groups, increasing code quality while lowering development effort.

Graphene oxide fiber microelectrodes with controlled sheet alignment for sensitive neurotransmitter detection.

Here, we synthesized and characterized graphene oxide (GO) fiber microelectrodes with controllable nanosheet orientation to study the extent to which sheet alignment and orientation impacts electrochemical detection of neurochemicals. The alignment of the GO nanosheets was characterized by scanning electron microscopy, Raman spectroscopy, and cyclic voltammetry. The electrochemical performance of GO microelectrodes and its suitability for subsecond detection of neurotransmitters was further evaluated by fast-scan cyclic voltammetry (FSCV). We have shown that the GO sheet alignment has a considerable effect on the electron transfer kinetics, frequency independent behavior, and detection suitability for specific neurotransmitters. Therefore, this fine-tuning aspect of the electrode surface for specific electrochemical detection should be taken into consideration for any future utilization of GO-based biological sensors.

Editors' Choice-Review-The Future of Carbon-Based Neurochemical Sensing: A Critical Perspective.

Carbon-based sensors have remained critical materials for electrochemical detection of neurochemicals, rooted in their inherent biocompatibility and broad potential window. Real-time monitoring using fast-scan cyclic voltammetry has resulted in the rise of minimally invasive carbon fiber microelectrodes as the material of choice for making measurements in tissue, but challenges with carbon fiber's innate properties have limited its applicability to understudied neurochemicals. Here, we provide a critical review of the state of carbon-based real-time neurochemical detection and offer insight into ways we envision addressing these limitations in the future. This piece focuses on three main hinderances of traditional carbon fiber based materials: diminished temporal resolution due to geometric properties and adsorption/desorption properties of the material, poor selectivity/specificity to most neurochemicals, and the inability to tune amorphous carbon surfaces for specific interfacial interactions. Routes to addressing these challenges could lie in methods like computational modeling of single-molecule interfacial interactions, expansion to tunable carbon-based materials, and novel approaches to synthesizing these materials. We hope this critical piece does justice to describing the novel carbon-based materials that have preceded this work, and we hope this review provides useful solutions to innovate carbon-based material development in the future for individualized neurochemical structures.

Porous Carbon Nanofiber-Modified Carbon Fiber Microelectrodes for Dopamine Detection.

We present a method to modify carbon-fiber microelectrodes (CFME) with porous carbon nanofibers (PCFs) to improve detection and to investigate the impact of porous geometry for dopamine detection with fast-scan cyclic voltammetry (FSCV). PCFs were fabricated by electrospinning, carbonizing, and pyrolyzing poly(acrylonitrile)-b-poly(methyl methacrylate) (PAN-b-PMMA) block copolymer nanofiber frameworks. Commonly, porous nanofibers are used for energy storage applications, but we present an application of these materials for biosensing which has not been previously studied. This modification impacted the topology and enhanced redox cycling at the surface. PCF modifications increased the oxidative current for dopamine 2.0 ± 0.1-fold (n = 33) with significant increases in detection sensitivity. PCF are known to have more edge plane sites which we speculate lead to the two-fold increase in electroactive surface area. Capacitive current changes were negligible providing evidence that improvements in detection are due to faradaic processes at the electrode. The ΔEp for dopamine decreased significantly at modified CFMEs. Only a 2.2 ± 2.2 % change in dopamine current was observed after repeated measurements and only 10.5 ± 2.8% after 4 hours demonstrating the stability of the modification over time. We show significant improvements in norepinephrine, ascorbic acid, adenosine, serotonin, and hydrogen peroxide detection. Lastly, we demonstrate that the modified electrodes can detect endogenous, unstimulated release of dopamine in living slices of rat striatum. Overall, we provide evidence that porous nanostructures significantly improve neurochemical detection with FSCV and echo the necessity for investigating the extent to which geometry impacts electrochemical detection.

Nanostructured carbon-fiber surfaces for improved neurochemical detection.

Fundamental insight into the extent to which the nanostructured surface and geometry impacts neurochemical interactions at electrode surfaces could provide significant advances in our ability to design and fabricate ultrasensitive neurochemical detection probes. Here, we investigate the extent to which the nanostructure of the carbon-fiber surface impacts detection of catecholamines and purines with fast-scan cyclic voltammetry (FSCV). Carbon-fibers were treated with argon (Ar) plasma to induce variations in the nano- and micro-structure without changing the functionalization of the surface. We tested variations in topology by measuring the extent to which the flow rate, RF power, and treatment time affect the surface roughness. Flow rates from 50-100 sccm, plasma power from 20-100 W, and treatment times from 30 s to 5 min were compared. Two Ar-treatments were chosen from the optimization studies for comparison, and the surface roughness was evaluated using atomic force microscopy (AFM). To ensure no changes in chemical composition, fibers were analyzed with X-ray photoelectron spectroscopy (XPS). On average, at the optimized Ar-plasma treatment procedure, oxidative current for adenosine and ATP increased by 3.5 ± 1.4-fold and 3.2 ± 0.6-fold, and guanosine and GTP by 1.7 ± 0.3-fold and 1.8 ± 0.3-fold, respectively (n = 9). Dopamine increased by 1.7 ± 0.3-fold. The extent to which changes in the electrode structure impact adsorption, sensitivity, and electron transfer rates were measured. A COMSOL Multiphysics simulation was developed to enable the modeling of mass transport of electroactive species at varying electrode geometries. Overall, this study provides critical insight into the extent to which the nanostructure of the surface impacts the electrochemical detection of neurochemicals.

The Wisconsin Oscillator: A Low-Cost Circuit for Powering Ion Guides, Funnels, and Traps.

In this work, we present the Wisconsin Oscillator, a small, inexpensive, low-power circuit for powering ion-guiding devices such as multipole ion guides, ion funnels, active ion-mobility devices, and non-mass-selective ion traps. The circuit can be constructed for under $30 and produces two antiphase RF waveforms of up to 250 Vp-p in the high kilohertz to low megahertz range while drawing less than 1 W of power. The output amplitude is determined by a 0-6.5 VDC drive voltage, and voltage amplification is achieved using a resonant LC circuit, negating the need for a large RF transformer. The Wisconsin Oscillator automatically oscillates with maximum amplitude at the resonant frequency defined by the onboard capacitors, inductors, and the capacitive load of the ion-guiding device. We show that our circuit can replace larger and more expensive RF power supplies without degradation of the ion signal and expect this circuit to be of use in miniature and portable mass spectrometers as well as in home-built systems utilizing ion-guiding devices.

Multichannel gas-uptake/evolution reactor for monitoring liquid-phase chemical reactions.

The design of a headspace pressure-monitoring reactor for measuring the uptake/evolution of gas in gas-liquid chemical transformations is described. The reactor features a parallel setup with ten-reactor cells, each featuring a low working volume of 0.2-2 ml, a pressure capacity from 0 to 150 PSIa, and a high sensitivity pressure transducer. The reactor cells are composed of commercially available disposable thick-walled glassware and compact monolithic weld assemblies. The software interface controls the reactor temperature while monitoring pressure in each of the parallel reactor cells. Reactions are easy to set up and yield high-density gas uptake/evolution data. This instrument is especially well suited to acquire quantitative time-course data for reactions with small quantities of gas consumed or produced.

Versatile Open-Source Photoreactor Architecture for Photocatalysis Across the Visible Spectrum.

Adoption of commercial photoreactors as standards for photocatalysis research could be limited by high cost. We report the development of the Wisconsin Photoreactor Platform (WPP), an open-source photoreactor architecture potentially suitable for general adoption. The WPP integrates inexpensive commercial components and common high-intensity LEDs in a 3D-printed enclosure. Dimensions and features of WPP reactors can be readily varied and configurations easily reproduced. WPP performance is evaluated using literature transformations driven by light of disparate wavelengths.

The XyloTron: Flexible, Open-Source, Image-Based Macroscopic Field Identification of Wood Products.

Forests, estimated to contain two thirds of the world's biodiversity, face existential threats due to illegal logging and land conversion. Efforts to combat illegal logging and to support sustainable value chains are hampered by a critical lack of affordable and scalable technologies for field-level inspection of wood and wood products. To meet this need we present the XyloTron, a complete, self-contained, multi-illumination, field-deployable, open-source platform for field imaging and identification of forest products at the macroscopic scale. The XyloTron platform integrates an imaging system built with off-the-shelf components, flexible illumination options with visible and UV light sources, software for camera control, and deep learning models for identification. We demonstrate the capabilities of the XyloTron platform with example applications for automatic wood and charcoal identification using visible light and human-mediated wood identification based on ultra-violet illumination and discuss applications in field imaging, metrology, and material characterization of other substrates.

Chaotic Analysis of Hippocampal and Cortical Sleep EEG during Various Vigilance States.

In this paper, we investigate the hippocampal and cortical sleep EEG of adult rats at different sleep stages by employing Lyapunov exponent and third-order cumulant measures to quantify and compare the chaotic and nonlinear behavior of EEG obtained during vigilance states of quiet- waking, slow-wave sleep, and rapid eye movement (REM) sleep. Lyapunov exponent was computed to characterize the EEG for chaos and third-order cumulant was used to measure the deviations from Gaussianity of the signal. Our results show positive Lyapunov exponents for all EEG states indicating a Iow- dimensional chaos for both REM and non-REM system. Furthermore, REM sleep EEG exhibits the largest Lyapunov exponent in both hippocampal and cortical EEG amongst other vigilance states. We also identified non-zero third-order cumulant for all the vigilance states which suggests their non- Gaussian behavior.

Three Dimensional Triply Resonant Sum Frequency Spectroscopy Revealing Vibronic Coupling in Cobalamins: Toward a Probe of Reaction Coordinates.

Triply resonant sum frequency (TRSF) spectroscopy is a fully coherent mixed vibrational-electronic spectroscopic technique that is ideally suited for probing the vibrational-electronic couplings that become important in driving reactions. We have used cyanocobalamin (CNCbl) and deuterated aquacobalamin (D2OCbl+) as model systems for demonstrating the feasibility of using the selectivity of coherent multidimensional spectroscopy to resolve electronic states within the broad absorption spectra of transition metal complexes and identify the nature of the vibrational and electronic state couplings. We resolve three short and long axis vibrational modes in the vibrationally congested 1400-1750 cm-1 region that are individually coupled to different electronic states in the 18 000-21 000 cm-1 region but have minimal coupling to each other. Double resonance with the individual vibrational fundamentals and their overtones selectively enhances the corresponding electronic resonances and resolves features within the broad absorption spectrum. This work demonstrates the feasibility of identifying coupling between different pairs of vibrational states with different electronic states that together form the reaction coordinate surface of transition metal enzymes.

Caffeine consumption disrupts hippocampal long-term potentiation in freely behaving rats.

Caffeine, one of the most commonly consumed psychoactive substances in the world, has long been known to alter neurological functions, such as alertness, attention, and memory. Despite caffeine's popularity, systematic investigations of its effects on synaptic plasticity in the brain are still lacking. Here we used a freely behaving rodent model of long-term potentiation (LTP), a frequently studied form of synaptic plasticity, to assess the effects of caffeine consumption on hippocampal plasticity. LTP, which is a persistent increase in the strength of synaptic connections between neurons, is a cellular mechanism widely considered to underlie the processes of learning and memory. A group of 10-week-old Sprague-Dawley rats were administered caffeine (1 g/L) in their drinking water 3 weeks prior to collection of electrophysiological data. Another group of age-matched animals received tap water and served as controls. Stimulating and recording electrodes were chronically implanted in the perforant pathway (PP) and dentate gyrus (DG) region of the hippocampus, respectively, to permit stable electrophysiological recordings of synaptic transmission at this synapse. Population spike amplitude (PSA) measures of LTP induction and duration were acquired in vivo while animals were freely behaving using a well-established electrophysiological recording protocol. Results indicate caffeine-treated rats (n = 9) had a significantly (P < 0.05) reduced level of LTP induction compared with controls (n = 10). More studies are needed to identify the exact mechanism through which caffeine alters LTP induction in this freely behaving model of synaptic plasticity.

Exploring Electronic Structure and Order in Polymers via Single-Particle Microresonator Spectroscopy.

PEDOT: PSS, a transparent electrically conductive polymer, finds widespread use in electronic devices. While empirical efforts have increased conductivity, a detailed understanding of the coupled electronic and morphological landscapes in PEDOT:PSS has lagged due to substantial structural heterogeneity on multiple length-scales. We use an optical microresonator-based absorption spectrometer to perform single-particle measurements, providing a bottom-up examination of electronic structure and morphology ranging from single PEDOT:PSS polymers to nascent films. Using single-particle spectroscopy with complementary theoretical calculations and ultrafast spectroscopy, we demonstrate that PEDOT:PSS displays bulk-like optical response even in single polymers. We find highly ordered PEDOT assemblies with long-range ordering mediated by the insulating PSS matrix and reveal a preferential surface orientation of PEDOT nanocrystallites absent in bulk films with implications for interfacial electronic communication. Our single-particle perspective provides a unique window into the microscopic structure and electronic properties of PEDOT:PSS.

Frequency-domain coherent multidimensional spectroscopy when dephasing rivals pulsewidth: Disentangling material and instrument response.

Ultrafast spectroscopy is often collected in the mixed frequency/time domain, where pulse durations are similar to system dephasing times. In these experiments, expectations derived from the familiar driven and impulsive limits are not valid. This work simulates the mixed-domain four-wave mixing response of a model system to develop expectations for this more complex field-matter interaction. We explore frequency and delay axes. We show that these line shapes are exquisitely sensitive to excitation pulse widths and delays. Near pulse overlap, the excitation pulses induce correlations that resemble signatures of dynamic inhomogeneity. We describe these line shapes using an intuitive picture that connects to familiar field-matter expressions. We develop strategies for distinguishing pulse-induced correlations from true system inhomogeneity. These simulations provide a foundation for interpretation of ultrafast experiments in the mixed domain.

Urinary albumin excretion and chronic kidney disease in children with vesicoureteral reflux.

BACKGROUND: Albuminuria is a potential biomarker of chronic kidney disease (CKD) in various glomerular diseases. Vesicoureteral reflux (VUR) often progresses to CKD, and study is required of use of albuminuria as a biomarker for this condition. The aim of this study was to evaluate the association between albuminuria and glomerular filtration rate (GFR) or filtration fraction (FF) in children with VUR. STUDY DESIGN: In this retrospective study, renal parameters of 141 children with VUR were investigated, using inulin clearance, FF, and albuminuria. The association between urinary albumin to creatinine ratio (ACR), GFR, and FF was analyzed in a continuous manner by calculating the ß coefficient, and also in a binary manner by calculating the OR. RESULTS: Using both continuous and binary analyses, ACR values were negatively and significantly associated to GFR values in patients with low, normal, or high FF values (Table). It was also positively and significantly associated with FF values in patients with low, normal or high GFR values (Table). No association was found between ACR and gender, VUR stages or laterality, number of urinary tract infection, presence of a single functional kidney, history of reflux surgery, or renal scars or hypertension. DISCUSSION: ACR is associated with CKD in patients with VUR. In addition, increased urinary albumin excretion cannot be completely and solely explained by decreased GFR and/or increased FF values. The two main limitations of this study are the crude assessment of renal scarring, which prevented finer analysis between albuminuria and renal scarring surface area, and that the study cohort may not be representative of the true VUR population. CONCLUSION: This study shows that albuminuria is associated with decreased renal function in patients with VUR and that it could be used to monitor renal function in this condition.

Developmental differences of dimension complexity of hippocampal EEG during REM sleep.

This paper uses spectral analysis and correlation dimension index to examine the developmental differences between the EEG measured from two hippocampal subfields, CA1 and the dentate gyrus. The study was focused on the hippocampal EEG during the vigilance state of REM sleep in freely moving rats of 15 and 90 days of age. Power spectra, magnitude-squared coherence, and correlation dimension were estimated. The correlation dimension adds a new interpretation from the nonlinear dynamics perspective, and we found that there are no significant developmental differences between the granule cells of the dentate gyrus and the pyramidal cells of area CA1 when the theta activity was present during REM sleep.

Application of independent component analysis to remove linear dependencies in EEG recorded in hippocampus.

Linear cross-spectral and nonlinear cross-bispectral analysis techniques were applied to EEG data recorded simultaneously in two subfields (CA1 and dentate gyrus) of the hippocampus in freely behaving neonatal rats during REM sleep. Linear dependencies between the two sites were specifically removed using independent component analysis (ICA). The cross-spectrum and the cross-bispectrum computed prior to ICA processing were compared with those after ICA processing to determine its effects. Our results indicate that ICA almost completely extracts the linear relationship in the theta frequency band between CA1 and the dentate gyrus. It is noted also that ICA processing significantly decreases the quadratic phase coupling (QPC) between the two hippocampal subfields.

[Patients with variations of sex development : an example of interdisciplinary care]. / Patients avec variation du développement sexuel : un exemple de prise en charge interdisciplinaire.

The medical, psychological and social aspects of disorders of sex development (DSD) represent a challenge for the management of these patients. However, advances in our understanding of the etiology and genetics of this condition, novel surgical approaches and the growing influence of patient groups as well as wider recognition of ethical issues have helped improve the care of patients with a DSD. Importantly, a multidisciplinary approach involving specialists is crucial for understanding and treating such rare and complex cases. According to the recommendations of the Swiss National Ethical Commission, we shall use the term « Variation of Sex Development ¼ rather than « Disorder of Sex Development ¼ in this publication. This article addresses the care of DSD patients throughout development from the point of view of specialists in complementary fields.

La prise en charge des personnes avec une variation du développement sexuel (VDS) (disorder of sex development, DSD) est un défi tant sur le plan médical, psychologique que social. L'amélioration des connaissances étiologiques et génétiques, les nouvelles approches chirurgicales et l'influence tant des groupes de patients que de la Commission d'éthique suisse ont considérablement modifié la vision de la prise en charge de ces personnes durant ces dernières décennies. Une approche pluridisciplinaire et spécialisée est cruciale pour appréhender ces situations rares et souvent complexes. Le point de vue des différents spécialistes impliqués au long de la vie dans la prise en charge d'une VDS est abordé dans cet article.