Human Foot Outperforms the Hand in Mechanical Pain Discrimination.

Tactile discrimination has been extensively studied, but mechanical pain discrimination remains poorly characterized. Here, we measured the capacity for mechanical pain discrimination using a two-alternative forced choice paradigm, with force-calibrated indentation stimuli (Semmes-Weinstein monofilaments) applied to the hand and foot dorsa of healthy human volunteers. In order to characterize the relationship between peripheral nociceptor activity and pain perception, we recorded single-unit activity from myelinated (A) and unmyelinated (C) mechanosensitive nociceptors in the skin using microneurography. At the perceptual level, we found that the foot was better at discriminating noxious forces than the hand, which stands in contrast to that for innocuous force discrimination, where the hand performed better than the foot. This observation of superior mechanical pain discrimination on the foot compared to the hand could not be explained by the responsiveness of individual nociceptors. We found no significant difference in the discrimination performance of either the myelinated or unmyelinated class of nociceptors between skin regions. This suggests the possibility that other factors such as skin biophysics, receptor density or central mechanisms may underlie these regional differences.

GO/CuO Nanohybrid-Based Carbon Dioxide Gas Sensors with an Arduino Detection Unit.

A gas sensor is a device that detects the presence of gases in a specific area. This research work demonstrates the effectiveness of gas sensors based on graphene oxide (GO) and copper oxide (CuO) semiconductor nanomaterials for the detection of carbon dioxide. GO and CuO were prepared by the modified Hummer's method and precipitation method using CuCl2 as a precursor, respectively. These materials are made into a hybrid using poly(vinyl alcohol) (PVA)/poly(vinylpyrrolidone) (PVP) polymer solutions of low concentrations and are spin coated onto the pattern-etched copper-clad substrate. The sensor is tested using a source measurement unit (SMU) to obtain the change in the resistance of the sensor in open air and in a carbon dioxide environment. The fabricated sensor with an Arduino microcontroller detection unit showed a good sensing response of 60%.

Hold me or stroke me? Individual differences in static and dynamic affective touch.

Low-threshold mechanosensory C-fibres, C-tactile afferents (CTs), respond optimally to sensations associated with a human caress. Additionally, CT-stimulation activates brain regions associated with processing affective states. This evidence has led to the social touch hypothesis, that CTs have a key role in encoding the affective properties of social touch. Thus, to date, the affective touch literature has focussed on gentle stroking touch. However, social touch interactions involve many touch types, including static, higher force touch such as hugging and holding. This study aimed to broaden our understanding of the social touch hypothesis by investigating relative preference for static vs dynamic touch and the influence of force on these preferences. Additionally, as recent literature has highlighted individual differences in CT-touch sensitivity, this study investigated the influence of affective touch experiences and attitudes, autistic traits, depressive symptomology and perceived stress on CT-touch sensitivity. Directly experienced, robotic touch responses were obtained through a lab-based study and vicarious touch responses through an online study where participants rated affective touch videos. Individual differences were determined by self-report questionnaire measures. In general, static touch was preferred over CT-non-optimal stroking touch, however, consistent with previous reports, CT-optimal stroking (velocity 1-10 cm/s) was rated most pleasant. However, static and CT-optimal vicarious touch were rated comparably for dorsal hand touch. For all velocities, 0.4N was preferred over 0.05N and 1.5N robotic touch. Participant dynamic touch quadratic terms were calculated for robotic and vicarious touch as a proxy CT-sensitivity measure. Attitudes to intimate touch significantly predict robotic and vicarious quadratic terms, as well as vicarious static dorsal hand touch ratings. Perceived stress negatively predicted robotic static touch ratings. This study has identified individual difference predictors of CT-touch sensitivity. Additionally, it has highlighted the context dependence of affective touch responses and the need to consider static, as well as dynamic affective touch.

Quality of Life in Mucormycosis Patients Post Discharge: A Pilot Study Using a New MQOL-36 Questionairre.

To evaluate the Quality of Life in Mucormycosis patients in our hospital using a new MQOL36 questionnaire post discharge. 37 cases between Apr 2021 to July 2021 were included in the study with a minimum follow up period of 4 weeks. They were administered Mucormycosis quality-of-life questionnaire (MQOL-36) either in person or via telephonic interview and answers were recorded into digital questionnaire modulated by us using a digital data recording app-KoBoCollect. Their demographic, clinical, imaging, histopathological and treatment data was retrieved and analysed. Most of the patients reported their health to be good with only 1 patient who had extensive cranial involvement reporting as poor and still undergoing repeated surgeries. 46.67% had no nasal complaints, 20% had nasal obstruction, 13.33% had nasal discharge with 2 patients complaining of crusting and 1 of whistling sound at quiet respiration. Most worrying factor was financial condition with 33.33% patients financially distraught and 43.33% being affected but barely managing at present. Only 2 patients reported no economic impact. Mucormycosis in COVID-19 has changed the face of otorhinolaryngology as we know it-while treating the disease is important, treating the post operative aftermath also becomes equally important. The MQOL-36 produces a quality-of-life profile scoring an individual's perception of quality of life in the following domains: Physical, Psychological, Level of Independence, Social Relationships and Environment. Monitoring the quality of life in patients post discharge could help us manage the enormous morbidity associated with the disease.

COVID 19 Associated Mucormycosis: Preventable Risk Factors Leading to a Better Prognosis: A Case Series.

India was severely affected by the second wave of coronavirus disease (COVID­19), leading to sudden expansive spread of Mucormycosis, presenting with sinusitis, blackish mucus secretions, discolouration of palate, facial pain, swelling and blurring of vision. Hyperglycemia, hypercoagulable state and elevated levels of serum ferritin were the major contributing factors in progression of the deadly disease. To highlight the correlation between Diabetes Mellitus, hyperferritenimia and elevated levels of D-Dimer with increased rate of incidence and poor prognosis of the disease. This study was undertaken in KLES Dr Prabhakar Kore Hospital & MRC, Belagavi, including 30 patients, between April to July 2021. Serum ferritin, HbA1C and D-Dimer were evaluated for patients on admission, along with the other routine blood investigations. The mean age was 50 years (49.99 ± 1.8), with a male predominance of 83.33% (25 Male patients). 93.33% patients had uncontrolled Diabetes Mellitus with a mean value of 10.12% (± 0.37) indicating Diabetes Mellitus to be the prime risk factor. The raised levels of serum ferritin with a mean of 662.01 ng/ml (± 129.18) and high levels of D-Dimer (Mean- 761.33 ± 151.8 ng/ml) also demonstrated their role as interlinked factors. Mucor epidemic was caused by convergence of interlinked risk factors. Awareness of red flag clinical features, prompt diagnosis, early initiation of treatment with amphotericin-B with aggressive surgical debridement are essential for successful outcome, to avoid high rate of mortality and morbidity rates in the mucormycosis patients.

Ion-Selective Membrane-Coated Graphene-Hexagonal Boron Nitride Heterostructures for Field-Effect Ion Sensing.

An intrinsic ion sensitivity exceeding the Nernst-Boltzmann limit and an sp 2 -hybridized carbon structure make graphene a promising channel material for realizing ion-sensitive field-effect transistors with a stable solid-liquid interface under biased conditions in buffered salt solutions. Here, we examine the performance of graphene field-effect transistors coated with ion-selective membranes as a tool to selectively detect changes in concentrations of Ca2+, K+, and Na+ in individual salt solutions as well as in buffered Locke's solution. Both the shift in the Dirac point and transconductance could be measured as a function of ion concentration with repeatability exceeding 99.5% and reproducibility exceeding 98% over 60 days. However, an enhancement of selectivity, by about an order magnitude or more, was observed using transconductance as the indicator when compared to Dirac voltage, which is the only factor reported to date. Fabricating a hexagonal boron nitride multilayer between graphene and oxide further increased the ion sensitivity and selectivity of transconductance. These findings incite investigating ion sensitivity of transconductance in alternative architectures as well as urge the exploration of graphene transistor arrays for biomedical applications.

Influence of interface in electrical properties of 3D printed structures.

The aligned bond interfaces resulting from the layer-by-layer nature of material extrusion-based additive manufacturing (MEAM) leads to anisotropic properties in printed parts. This study examines the anisotropy in electrical impedance and its variation with print parameters. Samples consisting of a stack of filaments are used to study the interfaces, which are the fundamental building block of MEAM, in a controlled manner. Anisotropy was quantified using the ratio of the impedance measured across (Z-specimen) and along (F-specimen) the fiber orientation. Although the conductivity of the material was found to change with extrusion temperature, the Z/F ratio was found to be constant (2.15 ± 0.23), regardless of the variation in thermal conditions imposed by varying extrusion temperature and print speed. By varying the distance over which impedance was measured, impedance scaling was understood. The scaling was found to be dependent on the extrusion temperature regardless of the variation of print speed by 266%; ~12.5 Ω per interface for 190 °C while ~6.5 Ω per interface for 230 °C, one-third of which was found to be contributed by fiber. While studying the cause for significant impedance at the interface, scanning electron microscopy study shows absence of airgaps at the interface, and energy dispersion spectroscopy shows absence of oxidation at the interface. The implications of specimen design and characterization proposed here allows for examination of a wide range of print parameters with reduction in material, time, and cost. Thus, by investigating the role of print parameters and scaling of impedance with interfaces, we seek to provide a framework to model and predict electrical behavior of electric sensors and actuators made with MEAM.

Characterizing the local oxidation nanolithography on highly oriented pyrolytic graphite.

Here, we characterize the patterns obtained through local oxidation nanolithography (LON) on highly oriented pyrolytic graphite as the write bias, speed, and force were varied. Different types of patterns-bumps, cracked bumps, and trenches-were obtained and characterized using four shape descriptors-pattern width, pattern height, cut width and cut depth. With an increase in write bias the obtained pattern type varied from bumps to cracked bumps to trenches. The use of a bias above 7.25 V resulted in trenches with increased variability in shape descriptor values. Similarly, an increase in write speed demonstrated a transition from trenches to cracked bumps to bumps. An increase in write force from 75 to 150 nN showed a shift in the threshold voltage from 4.25 V to just under 3.75 V and formed cracked bumps instead of bumps. These findings help solve the mystery of why bumps were not reported at threshold voltages before 2008. We believe these findings will be enable uniform reproduction and report of LON pattern.

Ion Sensing with Solution-Gated Graphene Field-Effect Sensors in the Frequency Domain.

Here, we examine the concept of frequency domain sensing with solution-gated graphene field-effect transistors, where a sine wave of primary frequency (1f) was applied at the gate and modulation of the power spectral density (PSD) of the drain-source current at 1f, 2f, and 3f was examined as the salt in the gate electrolyte was switched from KCl to CaCl2, and their concentrations were varied. The PSD at 1f, 2f, and 3f increased with the concentration of KCl or CaCl2, with the PSD at 1f being the most sensitive. We further correlated these changes to the shift in Dirac point. Switching the graphene substrate from oxide to hexagonal boron nitride, led to an improved device-to-device reproducibility and a significant reduction of noise, which translated to a higher signal-to-noise ratio and resolution in sensing salt concentrations. The signal-to-noise ratio at 1f was found to be a logarithmic function of KCl or CaCl2 concentration in the 0.1 to 1000 mM range.

Age-adjusted charlson comorbidity index and 30-day morbidity in pelvic surgeries.

INTRODUCTION: Charlson comorbidity index (CCI) is a validated tool enabling clinicians for prediction of adverse events posttherapy. In this study, we planned to estimate the predictive value of age-adjusted CCI (ACCI) in assessing the perioperative complication in oncological patients undergoing major pelvic surgeries. METHODS: This was a single arm, prospective, observational study, in which adult patients with pelvic malignancies undergoing pelvic surgeries were selected. The relationship between the ACCI and Grade 3-5 adverse events were tested using Fisher's test. RESULTS: The rate of Grade 3-5 adverse event rate was 16.7% (11 patients, n = 66). Among the whole cohort, 11 patients (16.7%) had high score on ACCI. The rate of Grade 3-5 adverse events was higher in the cohort of patients with high ACCI score (45.5% vs. 10.9%, P = 0.014). The sensitivity, specificity and negative and positive predictive values were 45.5%, 89.1%, 89.1%, and 45.5%, respectively. CONCLUSION: ACCI can predict for postsurgical adverse events. It has a high negative predictive value for nonoccurrence of adverse events.

Differential Stability of Biosensing Proteins on Transferred Mono/Bilayer Graphene.

Graphene, because its outstanding electrical and optical properties, has been an attractive material for developing biosensors and bioelectronics. The stability of proteins on graphene, as a function of its secondary structure, has been studied computationally; however, there has been a lack of experimental validity of such simulations results. This study examines the stability of two biosensing enzymes on graphene and in solution: horseradish peroxidase (an all α-helix protein) and glucose oxidase (a protein with both α-helix and ß-sheet content). At three different temperatures (4, 20, and 37 °C), glucose oxidase tethered to graphene was found to be more stable than when in solution. In contrast, horseradish peroxidase tethered to graphene showed rapid loss in activity than when in solution. This is the first experimental evidence showing differential stability of proteins on graphene, and we believe this is due to the difference in the secondary structure of the proteins.

Few-Flakes Reduced Graphene Oxide Sensors for Organic Vapors with a High Signal-to-Noise Ratio.

This paper reports our findings on how to prepare a graphene oxide-based gas sensor for sensing fast pulses of volatile organic compounds with a better signal-to-noise ratio. We use rapid acetone pulses of varying concentrations to test the sensors. First, we compare the effect of graphene oxide deposition method (dielectrophoresis versus solvent evaporation) on the sensor's response. We find that dielectrophoresis yields films with uniform coverage and better sensor response. Second, we examine the effect of chemical reduction. Contrary to prior reports, we find that graphene oxide reduction leads to a reduction in sensor response and current noise, thus keeping the signal-to-noise ratio the same. We found that if we sonicated the sensor in acetone, we created a sensor with a few flakes of reduced graphene oxide. Such sensors provided a higher signal-to-noise ratio that could be correlated to the vapor concentration of acetone with better repeatability. Modeling shows that the sensor's response is due to one-site Langmuir adsorption or an overall single exponent process. Further, the desorption of acetone as deduced from the sensor recovery signal follows a single exponent process. Thus, we show a simple way to improve the signal-to-noise ratio in reduced graphene oxide sensors.

Toward a Boron-Doped Ultrananocrystalline Diamond Electrode-Based Dielectrophoretic Preconcentrator.

This paper presents results on immunobeads-based isolation of rare bacteria and their capture at a boron-doped ultrananocrystalline diamond (BD-UNCD) electrode in a microfluidic dielectrophoretic preconcentrator. We systematically vary the bead surface chemistry and the BD-UNCD surface chemistry and apply dielectrophoresis to improve the specific and the nonspecific capture of bacteria or beads. Immunobeads were synthesized by conjugating antibodies to epoxy-/sulfate, aldehyde-/sulfate, or carboxylate-modified beads with or without poly(ethylene glycol) (PEG) coimmobilization. The carboxylate-modified beads with PEG provided the highest capture efficiency (∼65%) and selectivity (∼95%) in isolating live Escherichia coli O157:H7 from cultures containing 1000 E. coli O157:H7 colony-forming units (cfu)/mL, or ∼500 E. coli O157:H7 and ∼500 E. coli K12 cfu/mL. Higher specificity was achieved with the addition of PEG to the antibody-functionalized bead surface, highest with epoxy-/sulfate beads (85-86%), followed by carboxylate-modified beads (76-78%) and aldehyde-/sulfate beads (74-76%). The bare BD-UNCD electrodes of the preconcentrator successfully withstood 240 kV/m for 100 min that was required for the microfluidic dielectrophoresis of 1 mL of sample. As expected, the application of dielectrophoresis increased the specific and the nonspecific capture of immunobeads at the BD-UNCD electrodes; however, the capture specificity remained unaltered. The addition of PEG to the antibody-functionalized BD-UNCD surface had little effect on the specificity in immunobeads capture. These results warrant the fabrication of electrical biosensors with BD-UNCD so that dielectrophoretic preconcentration can be performed directly at the biosensing electrodes.

Nano/micro and spectroscopic approaches to food pathogen detection.

Despite continuing research efforts, timely and simple pathogen detection with a high degree of sensitivity and specificity remains an elusive goal. Given the recent explosion of sensor technologies, significant strides have been made in addressing the various nuances of this important global challenge that affects not only the food industry but also human health. In this review, we provide a summary of the various ongoing efforts in pathogen detection and sample preparation in areas related to Fourier transform infrared and Raman spectroscopy, light scattering, phage display, micro/nanodevices, and nanoparticle biosensors. We also discuss the advantages and potential limitations of the detection methods and suggest next steps for further consideration.

Nanostructuring of biosensing electrodes with nanodiamonds for antibody immobilization.

While chemical vapor deposition of diamond films is currently cost prohibitive for biosensor construction, in this paper, we show that sonication-assisted nanostructuring of biosensing electrodes with nanodiamonds (NDs) allows harnessing the hydrolytic stability of the diamond biofunctionalization chemistry for real-time continuous sensing, while improving the detector sensitivity and stability. We find that the higher surface coverages were important for improved bacterial capture and can be achieved through proper choice of solvent, ND concentration, and seeding time. A mixture of methanol and dimethyl sulfoxide provides the highest surface coverage (33.6 ± 3.4%) for the NDs with positive zeta-potential, compared to dilutions of dimethyl sulfoxide with acetone, ethanol, isopropyl alcohol, or water. Through impedance spectroscopy of ND-seeded interdigitated electrodes (IDEs), we found that the ND seeds serve as electrically conductive islands only a few nanometers apart. Also we show that the seeded NDs are amply hydrogenated to be decorated with antibodies using the UV-alkene chemistry, and higher bacterial captures can be obtained compared to our previously reported work with diamond films. When sensing bacteria from 10(6) cfu/mL E. coli O157:H7, the resistance to charge transfer at the IDEs decreased by ∼ 38.8%, which is nearly 1.5 times better than that reported previously using redox probes. Further in the case of 10(8) cfu/mL E. coli O157:H7, the charge transfer resistance changed by ∼ 46%, which is similar to the magnitude of improvement reported using magnetic nanoparticle-based sample enrichment prior to impedance detection. Thus ND seeding allows impedance biosensing in low conductivity solutions with competitive sensitivity.

Control of Nanoscale Environment to Improve Stability of Immobilized Proteins on Diamond Surfaces.

Immunoassays for detection of bacterial pathogens rely on the selectivity and stability of bio-recognition elements such as antibodies tethered to sensor surfaces. The search for novel surfaces that improve the stability of biomolecules and assay performance has been pursued for a long time. However, the anticipated improvements in stability have not been realized in practice under physiological conditions because the surface functionalization layers on commonly used substrates, silica and gold, are themselves unstable on time scales of days. In this paper, we show that covalent linking of antibodies to diamond surfaces leads to substantial improvements in biological activity of proteins as measured by the ability to selectively capture cells of the pathogenic bacterium Escherichia coli O157:H7 even after exposure to buffer solutions at 37 °C for extended periods of time, approaching 2 weeks. Our results from ELISA, XPS, fluorescence microscopy, and MD simulations suggest that by using highly stable surface chemistry and controlling the nanoscale organization of the antibodies on the surface, it is possible to achieve significant improvements in biological activity and stability. Our findings can be easily extended to functionalization of micro and nanodimensional sensors and structures of biomedical diagnostic and therapeutic interest.

Synthesis, characterization, and photoactivity of Ta2O5-grafted SiO2 nanoparticles.

Herein, we discuss the synthesis as well as material and photochemical characterization of nanometer-sized Ta(2)O(5) decorated, in a controlled fashion, on top of 20 nm diameter SiO(2) particles to yield a composite oxide with a tunable band-gap width. Particular emphasis is paid to control of particle size, and control of the distribution of the overlying oxide. The nanoscale dimension imparts a high surface area and introduces quantum confinement effects that displace the conduction band more negatively and the valence band more positively on the electrochemical scale of potentials. This band shift results in an increase of the number of possible participants in photocatalytic reactions. The band shift is shown to result in an increase in driving force for thermodynamically feasible reactions. By decorating SiO(2) with smaller-sized Ta(2)O(5), the interplay of the Lewis acidity of SiO(2) and the contact area between Ta(2)O(5) and SiO(2) is utilized to develop a photocatalyst with higher photoactivity than pure Ta(2)O(5).

Surface functionalization of thin-film diamond for highly stable and selective biological interfaces.

Carbon is an extremely versatile family of materials with a wide range of mechanical, optical, and mechanical properties, but many similarities in surface chemistry. As one of the most chemically stable materials known, carbon provides an outstanding platform for the development of highly tunable molecular and biomolecular interfaces. Photochemical grafting of alkenes has emerged as an attractive method for functionalizing surfaces of diamond, but many aspects of the surface chemistry and impact on biological recognition processes remain unexplored. Here we report investigations of the interaction of functionalized diamond surfaces with proteins and biological cells using X-ray photoelectron spectroscopy (XPS), atomic force microscopy, and fluorescence methods. XPS data show that functionalization of diamond with short ethylene glycol oligomers reduces the nonspecific binding of fibrinogen below the detection limit of XPS, estimated as > 97% reduction over H-terminated diamond. Measurements of different forms of diamond with different roughness are used to explore the influence of roughness on nonspecific binding onto H-terminated and ethylene glycol (EG)-terminated surfaces. Finally, we use XPS to characterize the chemical stability of Escherichia coli K12 antibodies on the surfaces of diamond and amine-functionalized glass. Our results show that antibody-modified diamond surfaces exhibit increased stability in XPS and that this is accompanied by retention of biological activity in cell-capture measurements. Our results demonstrate that surface chemistry on diamond and other carbon-based materials provides an excellent platform for biomolecular interfaces with high stability and high selectivity.

Partially buried microcolumns for micro gas analyzers.

This article demonstrates the feasibility of making a partially buried micro gas chromatography (micro-GC) column with a rounded channel wall profile, which enables coating the stationary phase more uniformly and shows better separation characteristics than a square deep reactive ion etched (DRIE) wall profile. A buried structure fabrication method was adapted to fabricate 34 cm long, 165 microm wide, and 65 microm deep partially buried microcolumns, which had a unique rounded microcolumn wall profile similar to that of a flattened circular tube. The separation characteristics were compared to that of a 34 cm long, 100 microm x 100 microm square DRIE microcolumn, which had a similar hydraulic diameter. Minimum height equivalent to a theoretical plate (HETP) and reduced HETP of 0.39 mm and 6.02, respectively, with a retention factor of 6.3 were obtained on the coated partially buried microcolumn compared to 0.66 mm and 6.73, respectively, on the coated square DRIE microcolumn with a similar retention factor. The partially buried microcolumn was found to perform closer to the theoretical approximation and this could be attributed to the uniform phase deposition in the partially buried microcolumn compared to the square DRIE microcolumn. A 10 component mix was separated on the partially buried microcolumn in 3.8 s with the maximum peak width at half-height equal to 0.2 s, while a similar mix separated at higher pressure and temperature conditions on the square DRIE microcolumn in 4.6 s. The rounded corners allowed depositing thinner stationary phase, which was reflected in the faster elution of n-C(12) on the partially buried microcolumn compared to the square DRIE microcolumn. The better performance of the partially buried microcolumn may be attributed to either the rounded channel wall profile, the clean channel structures produced by the fabrication process, or the double-etched wall profile, which lowers the Taylor-Aris dispersion.