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Ethylene glycol (EG), citrate and EDTA stabilized Eu(III) doped CaF2 nanoparticles were synthesized following colloidal precipitation method. With EDTA, highly monodisperse cubic nanoparticles (NPs) were formed which changes to quasi-spherical morphology when the capping ligand changes to TSC and EG associated with a broader size distribution. Generations of larger NPs were produced through kinetically controlled seeded-growth method where the ligands directly affect the size tunability. The homogeneity of the growth process was maximized by the adjustment of reaction parameters like temperature and concentration of precursor. Under the same reaction conditions, better kinetic control of the growth process and the ease of tuning the size by the ligands follow the order: EDTA > citrate > EG. The Eu3+ emission intensities characteristic of 5D0 → 7Fn for the NPs increases when the ligand changes from EG to EDTA through citrate. Among the generations of NPs capped by a particular ligand, the dependence of luminescence intensity on size is observed. With decreasing size, there is luminescence enhancement for NPs stabilized by citrate and EDTA while the trend is opposite for EG stabilized particles. [ABSTRACT FROM AUTHOR]

Monodispersed Pd nanoparticles ranging from 2.8 to 8.0 nm with narrow size distribution are prepared and supported on TiO 2 for photo-thermal catalytic RWGS reaction. The catalytic activity presents volcano-type dependence over Pd sizes with 6.3 Pd/TiO 2 exhibiting the highest activity. [Display omitted] • A library of monodispersed Pd nanoparticles with successively increased sizes from 2.8, 3.4, 4.7, 5.3, 6.3 and 8.1 nm were prepared. • The photo-thermal catalytic activity towards RWGS reaction presents volcano-type dependence over Pd sizes with 6.3 Pd/TiO 2 giving the highest activity. • The size-modulated activity can be attributed to the tunable surface electronic properties including metal-support interaction and quantum size effect. Size of metal nanoparticles significantly influences their catalytic behaviors. However, it is still challenging to obtain monodispersed metal nanoparticles with successively tuned sizes to unveil their size-dependent catalytic performances, especially for photo-thermal catalytic reverse water–gas shift (RWGS) reaction. Herein, a library of Pd nanoparticles of 2.8, 3.4, 4.7, 5.3, 6.3 and 8.1 nm were synthesized and supported on TiO 2 for photo-thermal catalytic RWGS reaction. The catalytic activity presented volcano-like dependence on sizes of Pd nanoparticles with 6.3 Pd/TiO 2 exhibiting the highest catalytic efficiency. Based on the results of X-ray photoelectron spectroscopic analysis, photo-to-thermal conversion efficiency evaluation and density functional theory (DFT) calculations following the formate (*HCOO) pathway revealed by in situ diffuse reflectance infrared Fourier transform spectroscopy (in situ DRIFTS) measurements, the volcano-type tendency in catalytic activity could be attributed to the superposition of size-governed surface electronic properties over Pd nanoparticles. [ABSTRACT FROM AUTHOR]

The synaptic mechanisms of feature coding in the visual cortex are poorly understood, particularly in awake animals. The ratio between excitation (E) and inhibition (I) might be constant across stimulus space, controlling only the gain and timing of neuronal responses, or it might change, directly contributing to feature coding. Whole-cell recordings in L2/3 of awake mice revealed that the E/I ratio systematically declines with increasing stimulus contrast or size. Suppressing somatostatin (SOM) neurons enhanced the E and I underlying size tuning, explaining SOM neurons' role in surround suppression. These data imply that contrast and size tuning result from a combination of a changing E/I ratio and the tuning of total synaptic input. Furthermore, they provide experimental support in awake animals for the "Stabilized Supralinear Network," a model that explains diverse cortical phenomena, and suggest that a decreasing E/I ratio with increasing cortical drive could contribute to many different cortical computations.

Metal-oxide-based electrodes play a crucial role in various transparent conductive oxide (TCO) applications. Among the p-type materials, nickel oxide is a promising electrically conductive material due to its good stability, large bandgap, and deep valence band. Here, we display pristine and 3 at.%V-doped NiO synthesized by the solvothermal decomposition method. The properties of both the pristine and 3 at.%V:NiO nanoparticles were characterized by field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), X-ray diffractometry (XRD), Raman spectroscopy, ultraviolet–visible spectroscopy (UV–vis), and X-ray photoelectron spectroscopy (XPS). The film properties were characterized by atomic force microscopy (AFM) and a source meter. Our results suggest that incorporation of vanadium into the NiO lattice significantly improves both electrical conductivity and hole extraction. Also, 3 at.%V:NiO exhibits a lower crystalline size when compared to pristine nickel oxide, which maintains the reduction of surface roughness. These results indicate that vanadium is an excellent dopant for NiO. [ABSTRACT FROM AUTHOR]

Surround modulation has been abundantly studied in several mammalian brain areas, including the primary visual cortex, lateral geniculate nucleus, and superior colliculus (SC), but systematic analysis is lacking in the avian optic tectum (OT, homologous to mammal SC). Here, multi-units were recorded from pigeon (Columba livia) OT, and responses to different sizes of moving, flashed squares, and bars were compared. The statistical results showed that most tectal neurons presented suppressed responses to larger stimuli in both moving and flashed paradigms, and suppression induced by flashed squares was comparable with moving ones when the stimuli center crossed the near classical receptive field (CRF) center, which corresponded to the full surrounding condition. Correspondingly, the suppression grew weaker when the stimuli center moved across the CRF border, equivalent to partially surrounding conditions. Similarly, suppression induced by full surrounding flashed squares was more intense than by partially surrounding flashed bars. These results suggest that inhibitions performed on tectal neurons appear to be full surrounding rather than locally lateral. This study enriches the understanding of surround modulation properties of avian tectum neurons and provides possible hypotheses about the arrangement of inhibitions from other nuclei, both of which are important for clarifying the mechanism of target detection against clutter background performed by avians.

The local field potential (LFP) is an extracellular electrical signal associated with neural ensemble input and dendritic signaling. Previous studies have linked gamma band oscillations of the LFP in cortical circuits to sensory stimuli encoding, attention, memory, and perception. Inconsistent results regarding gamma tuning for visual features were reported, but it remains unclear whether these discrepancies are due to variations in electrode properties. Specifically, the surface area and impedance of the electrode are important characteristics in LFP recording. To comprehensively address these issues, we conducted an electrophysiological study in the V1 region of lightly anesthetized mice using two types of electrodes: one with higher impedance (1 MΩ) and a sharp tip (10 μm), while the other had lower impedance (100 KΩ) but a thicker tip (200 μm). Our findings demonstrate that gamma oscillations acquired by sharp-tip electrodes were significantly stronger than those obtained from thick-tip electrodes. Regarding size tuning, most gamma power exhibited surround suppression at larger gratings when recorded from sharp-tip electrodes. However, the majority showed enhanced gamma power at larger gratings when recorded from thick-tip electrodes. Therefore, our study suggests that microelectrode parameters play a significant role in accurately recording gamma oscillations and responsive tuning to sensory stimuli., (© The Author(s) 2024. Published by Oxford University Press. All rights reserved. For permissions, please e-mail: journals.permission@oup.com.)

Neurons in the visual system integrate over a wide range of spatial scales. This diversity is thought to enable both local and global computations. To understand how spatial information is encoded across the mouse visual system, we use two-photon imaging to measure receptive fields (RFs) and size-tuning in primary visual cortex (V1) and three downstream higher visual areas (HVAs: LM (lateromedial), AL (anterolateral), and PM (posteromedial)) in mice of both sexes. Neurons in PM, compared with VI or the other HVAs, have significantly larger RF sizes and less surround suppression, independent of stimulus eccentricity or contrast. To understand how this specialization of RFs arises in the HVAs, we measured the spatial properties of VI inputs to each area. Spatial integration of VI axons was remarkably similar across areas and significantly different from the tuning of neurons in their target HVAs. Thus, unlike other visual features studied in this system, specialization of spatial integration in PM cannot be explained by specific projections from VI to the HVAs. Further, the differences in RF properties could not be explained by differences in convergence of V1 inputs to the HVAs. Instead, our data suggest that distinct inputs from other areas or connectivity within PM may support the area's unique ability to encode global features of the visual scene, whereas V1, LM, and AL may be more specialized for processing local features. [ABSTRACT FROM AUTHOR]

Activity of neurons in primary visual cortex is shaped by sensory and behavioral context. However, the long-term stability of the influence of contextual factors in the mature cortex remains poorly understood. To investigate this, we used two-photon calcium imaging to track the influence of surround suppression and locomotion on individual neurons over 14 days. We found that highly active excitatory neurons and parvalbumin-positive (PV+) interneurons exhibited relatively stable modulation by visual context. Similarly, most neurons exhibited a stable yet distinct degree of modulation by locomotion. In contrast, less active excitatory neurons exhibited plasticity in visual context influence, resulting in increased suppression. These findings suggest that the mature visual cortex possesses stable subnetworks of neurons, differentiated by cell type and activity level, which have distinctive and stable interactions with sensory and behavioral contexts, as well as other less active and more labile neurons, which are sensitive to visual experience.

Metal-oxide-based electrodes play a crucial role in various transparent conductive oxide (TCO) applications. Among the p-type materials, nickel oxide is a promising electrically conductive material due to its good stability, large bandgap, and deep valence band. Here, we display pristine and 3 at.%V-doped NiO synthesized by the solvothermal decomposition method. The properties of both the pristine and 3 at.%V:NiO nanoparticles were characterized by field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), X-ray diffractometry (XRD), Raman spectroscopy, ultraviolet–visible spectroscopy (UV–vis), and X-ray photoelectron spectroscopy (XPS). The film properties were characterized by atomic force microscopy (AFM) and a source meter. Our results suggest that incorporation of vanadium into the NiO lattice significantly improves both electrical conductivity and hole extraction. Also, 3 at.%V:NiO exhibits a lower crystalline size when compared to pristine nickel oxide, which maintains the reduction of surface roughness. These results indicate that vanadium is an excellent dopant for NiO.

To reduce statistical redundancy of natural inputs and increase the sparseness of coding, neurons in primary visual cortex (VI) show tuning for stimulus size and surround suppression. This integration of spatial information is a fundamental, context-dependent neural operation involving extensive neural circuits that span across all cortical layers of a VI column, and reflects both feedforward and feedback processing. However, how spatial integration is dynamically coordinated across cortical layers remains poorly understood. We recorded single- and multiunit activity and local field potentials across V1 layers of awake mice (both sexes) while they viewed stimuli of varying size and used dynamic Bayesian model comparisons to identify when laminar activity and interlaminar functional interactions showed surround suppression, the hallmark of spatial integration. We found that surround suppression is strongest in layer 3 (L3) and L4 activity, where suppression is established within ~ 10 ms after response onset, and receptive fields dynamically sharpen while suppression strength increases. Importantly, we also found that specific directed functional connections were strongest for intermediate stimulus sizes and suppressed for larger ones, particularly for connections from L3 targeting L5 and L1. Together, the results shed light on the different functional roles of cortical layers in spatial integration and on how L3 dynamically coordinates activity across a cortical column depending on spatial context. [ABSTRACT FROM AUTHOR]

Summary Activity of neurons in primary visual cortex is shaped by sensory and behavioral context. However, the long-term stability of the influence of contextual factors in the mature cortex remains poorly understood. To investigate this, we used two-photon calcium imaging to track the influence of surround suppression and locomotion on individual neurons over 14 days. We found that highly active excitatory neurons and parvalbumin-positive (PV+) interneurons exhibited relatively stable modulation by visual context. Similarly, most neurons exhibited a stable yet distinct degree of modulation by locomotion. In contrast, less active excitatory neurons exhibited plasticity in visual context influence, resulting in increased suppression. These findings suggest that the mature visual cortex possesses stable subnetworks of neurons, differentiated by cell type and activity level, which have distinctive and stable interactions with sensory and behavioral contexts, as well as other less active and more labile neurons, which are sensitive to visual experience. [ABSTRACT FROM AUTHOR]

We investigate the deposition temperature, pH and deposition time that govern evolution of the nanoparticle shape, size and density of ZnSe nanoparticle arrays. The nanoparticle arrays were grown on glass substrate using a facile chemical bath deposition method. The samples were also characterized by absorbance spectra for energy band gap determination and scanning electron microscopy. In comparison to other similar works, our method is simple, low cost and can be easily controlled. We find that temperature helps to tailoring the nanoparticle shape and has a critical role in comparison with other parameters such as pH and deposition time. [ABSTRACT FROM AUTHOR]

In the primary visual cortex (V1), a neuronal response to stimulation of the classical receptive field (CRF) is predominantly suppressed by a stimulus presented outside the CRF (extraclassical receptive field, ECRF), a phenomenon referred to as ECRF suppression. To elucidate the neuronal mechanisms and origin of ECRF suppression in V1 of anesthetized cats, we examined the temporal properties of the spatial extent and orientation specificity of ECRF suppression in V1 and the lateral geniculate nucleus (LGN), using stationary-flashed sinusoidal grating. In V1, we found three components of ECRF suppression: 1) local and fast, 2) global and fast, and 3) global and late. The local and fast component, which resulted from within 2° of the boundary of the CRF, started no more than 10 ms after the onset of the CRF response and exhibited low specificity for the orientation of the ECRF stimulus. These spatiotemporal properties corresponded to those of geniculate ECRF suppression, suggesting that the local and fast component of V1 is inherited from the LGN. In contrast, the two global components showed rather large spatial extents ∼5° from the CRF boundary and high specificity for orientation, suggesting that their possible origin is the cortex, not the LGN. Correspondingly, the local component was observed in all neurons of the thalamocortical recipient layer, while the global component was biased toward other layers. Therefore, we conclude that both subcortical and cortical mechanisms with different spatiotemporal properties are involved in ECRF suppression. [ABSTRACT FROM AUTHOR]

Responses of many neurons in primary visual cortex (V1) are suppressed by stimuli exceeding the classical receptive field (RF), an important property that might underlie the computation of visual saliency. Traditionally, it has proven difficult to disentangle the underlying neural circuits, including feedforward, horizontal intracortical, and feedback connectivity. Since circuit-level analysis is particularly feasible in the mouse, we asked whether neural signatures of spatial integration in mouse V1 are similar to those of higher-order mammals and investigated the role of parvalbumin-expressing (PV+) inhibitory interneurons. Analogous to what is known from primates and carnivores, we demonstrate that, in awake mice, surround suppression is present in the majority of V1 neurons and is strongest in superficial cortical layers. Anesthesia with isoflurane-urethane, however, profoundly affects spatial integration: it reduces the laminar dependency, decreases overall suppression strength, and alters the temporal dynamics of responses. We show that these effects of brain state can be parsimoniously explained by assuming that anesthesia affects contrast normalization. Hence, the full impact of suppressive influences in mouse V1 cannot be studied under anesthesia with isoflurane-urethane. To assess the neural circuits of spatial integration, we targeted PV+ interneurons using optogenetics. Optogenetic depolarization of PV+ interneurons was associated with increased RF size and decreased suppression in the recorded population, similar to effects of lowering stimulus contrast, suggesting that PV+ interneurons contribute to spatial integration by affecting overall stimulus drive. We conclude that the mouse is a promising model for circuit-level mechanisms of spatial integration, which relies on the combined activity of different types of inhibitory interneurons. [ABSTRACT FROM AUTHOR]

Abstract: Giant unilamellar vesicles (GUVs) of dioleoylphosphatidycholine (DOPC) and dipalmitoylphosphatidylethanolamine (DPPE) containing NiCl2 or NiSO4 have been used as templates to prepare nanoparticles of nickel oxide of 35–75nm size. The GUVs have been studied by steady state fluorescence anisotropy, fluorescence life time measurements, optical microscopy and confocal laser scanning microscopy (CLSM). In general, the GUVs containing the nickel salts show a contraction in size (ranging from 14 to 19μm) compared with pure GUVs (20–30μm). Fluorescence anisotropy values show that GUVs with NiCl2 are better organized compared with those containing NiSO4. Transmission electron microscopy (TEM), and powder XRD studies corroborate these findings. The stacking of the lipids in the presence of Ni2+ leading to contraction in the GUVs has been modeled using Gaussian 03 package. Nickel sulfide formed from mixing these vesicles with Na2S containing vesicles, has been further calcined to obtain nanosized clusters of nickel oxide. Scanning electron micrographs of the nickel oxide formed from GUVs with NiCl2 show smaller sizes (35–45nm) with wider size distributions compared with those from GUVs with NiSO4 (sizes 50–75nm) that have more uniform sizes. Results suggest that by judicious choice of different anions in the metal salts a method to structure and tune the sizes and morphology of the nanoclusters using GUVs as templates is possible. [Copyright &y& Elsevier]

Abstract: Silica nanoparticles have been prepared from tetraethylorthosilicate dissolved in ethanol followed by base-catalyzed condensation. Earlier works reported that at least four parameters, namely concentration of tetraethylorthosilicate, ethanol, water and ammonia solution are needed to be optimized for the size tuning of silica nanoparticles. In this work size tuning of 5nm–250nm has been achieved by varying a single synthesis parameter i.e., the concentration of ammonia solution. Oxygen plasma was found to be successful for generating pores on silica nanoparticles without using any structure directing agents. The properties and morphology of nanoparticles were investigated by transmission electron microscopy, scanning electron microscopy, energy dispersive X- ray spectroscopy and Fourier transformed infrared spectroscopy. [Copyright &y& Elsevier]

Abstract: A neural response to a sensory stimulus in cerebral cortex is modulated when other stimuli are presented simultaneously. The other stimuli can modulate responses even when they do not drive the neural output alone, indicating a non-linear summation of synaptic activity. The mechanisms of the nonlinearity have remained unclear. Here, I explore a model which considers both network and intracellular processes, and which can account for various types of contextual modulation. The processes include synaptic sensitivity function, determination of inhibition strength, dendritic decay of membrane voltage, and summation of excitatory and inhibitory membrane voltages. First, the model assumes that excitatory and inhibitory units have the same input sensitivity function, which is more broadly tuned than the output tuning function. Second, a central property of the model is that inhibition is a fraction of excitation, determined by covariance between the input and the sensitivity function. With proper fraction, a model neuron sums apparently decorrelated input, regardless of correlations in the original input. Third, the model assumes that synaptic input lands anisotropically on the dendrites, which together with passive dendritic decay cause exponential decay in summation along the input space. This explains the difference between input sensitivity function and output tuning function, and thus accounts for the division between driving classical and modulating extra-classical receptive fields. The model simulations replicate single-cell area summation function, far surround facilitation, and a shift in tuning function due to contextual stimulation. The model is very general, and should be applicable to various interactions between cortical representations. [Copyright &y& Elsevier]

Abstract: Size tuning of silicon (Si) nanoparticles (NPs) with the use of meso-porous silicon (meso-PS) free-standing layers is reported for the first time. Accumulation of Si NPs inside the membrane pores during the filtering process (NP transport through the meso-PS) leads to an auto-filtration effect (called Si-by-Si (SBS) filtration) allowing more efficient size selection of the NPs. General complex fractal shape and surface chemistry of the whole porous network, layer thickness as well as a given initial NP size dispersion determine final size of the NPs in the filtered solution. Moreover, quantum of step-like NP size increasing equal to 0.12nm was found. [Copyright &y& Elsevier]

Abstract: In this paper, we present the synthesis of organic nanocrystals in a 3D hydrodynamic focusing device through a non-solvent crystallization process. This microreactor was designed in order to control the supersaturation level, while manipulating mixing conditions, and to avoid fouling and clogging within the main channel. Rubrene, the molecule of interest, was dissolved in a THF–ethanol mixture and was injected through a silica capillary. Two side flows containing the non-solvent and the surfactant, water and CTACl respectively, surround and interact with the capillary flow and mixing occurs through diffusion. First, we quantify the water diffusion process within the focused beam by confocal fluorescence microscopy in the presence of fluorescein. It is shown here that the efficiency and the quality of the mixing between the aqueous side flow and the focused organic solution are improved by increasing the side flow rate to the capillary flow rate ratio, i.e. the focusing ratio. Second, the synthesis of rubrene crystals were performed under a variety of flow rate conditions. We show that, by increasing the focusing ratio (from 5 to 40), the mean size of nanocrystals decreases (from 110 to 50nm). The characterization of the mixing process allows for a better understanding of rubrene nanocrystal synthesis: a fast supersaturation induces the generation of numerous nuclei, which limits the crystal growth. Herein, we show that the 3D hydrodynamic focusing microreactor efficiently produces organic nanoparticles of controlled size, without the deposition of large, unwanted crystals on the microchannel walls. [Copyright &y& Elsevier]

Simple Summary: Surround modulation is a basic visual attribute of sensory neurons in many species and has been extensively characterized in mammal primary visual cortex, lateral geniculate nucleus, and superior colliculus. Little attention has been paid to birds, which have a highly developed visual system. We undertook a systematic analysis on surround modulation properties of tectal neurons in pigeons (Columba livia). This study complements existing studies on surrounding modulation properties in non-mammalian species and deepens the understanding of mechanisms of figure–background segmentation performed by avians. Surround modulation has been abundantly studied in several mammalian brain areas, including the primary visual cortex, lateral geniculate nucleus, and superior colliculus (SC), but systematic analysis is lacking in the avian optic tectum (OT, homologous to mammal SC). Here, multi-units were recorded from pigeon (Columba livia) OT, and responses to different sizes of moving, flashed squares, and bars were compared. The statistical results showed that most tectal neurons presented suppressed responses to larger stimuli in both moving and flashed paradigms, and suppression induced by flashed squares was comparable with moving ones when the stimuli center crossed the near classical receptive field (CRF) center, which corresponded to the full surrounding condition. Correspondingly, the suppression grew weaker when the stimuli center moved across the CRF border, equivalent to partially surrounding conditions. Similarly, suppression induced by full surrounding flashed squares was more intense than by partially surrounding flashed bars. These results suggest that inhibitions performed on tectal neurons appear to be full surrounding rather than locally lateral. This study enriches the understanding of surround modulation properties of avian tectum neurons and provides possible hypotheses about the arrangement of inhibitions from other nuclei, both of which are important for clarifying the mechanism of target detection against clutter background performed by avians. [ABSTRACT FROM AUTHOR]

Abstract: We present a method of spatial and dimensional controlled formation of CdS quantum dots into polymer matrices by light irradiation. The initial samples consist of Cd thiolate precursors doped in TOPAS polymer matrix. Under pulsed UV laser irradiation the precursors are photolysed driving to the nucleation of CdS nanocrystals, with increasing size and concentration, related to the number of UV pulses. The formed quantum dots are localized in the irradiated area, while the host polymer remains macroscopically unaffected by the UV irradiation. In this study we investigate how the formation of the nanocrystals (size, dimensions, and concentration) is affected by the use of different irradiation conditions (wavelength, number of pulses), revealing information about the different pathways followed during the formation. The change of the size of the dots results in the change of the peak of their emission due to the quantum size effect, which is studied by fluorescence measurements. The results are reinforced by TEM microscopy and by XRD measurements. The main advantages of the presented method are the size tuning of the produced dots and their spatial confinement inside the host matrix, not possible by the other methods used until now (thermal annealing, mixing etc.). [Copyright &y& Elsevier]

• The cadmium selenium quantum dots with three capping agents were synthesized in aqueous solution. • The effect of capping agent on the nucleation and particle growth process during synthesize of QDs. • Uv-Vis and fluorescence spectroscopy techniques were applied for size determination of the QDs. • The size of quantum dots was controlled by selecting an appropriate of capping gents. In this study cadmium selenium quantum dots (CdSe QDs) were synthesized with different capping agents namely, l-cysteine, mercaptosuccinic acid and thioglycolic in aqueous solution. The effect of capping agent on the nucleation and particle growth process was investigated. Electronic absorption and emission fluorescence spectroscopy techniques were applied to map out the size evolution of the QDs. The methods of SEM, EDX, XRD and FTIR were also used for characterization of the prepared samples. The average diameters of the synthesized quantum dots were estimated using different methods. Results revealed that the order of particles size was obtained as follow: CdSe-MSA > CdSe-LCY > CdSe-TGA. Results also showed that the TGA has the strongest binding ability with the QDs surface; in contrast MSA has the weakest binding ability. Results indicated that there is a mutual relationship between changing the bandwidth and the rate of growing particle size of the quantum dot, so that the particles with slow growing rate (CdSe-TGA, 12 h) its bandwidth varies smoothly. Also the magnitude of bandwidth of the spectrum is fairly dependent to the size of the CdSe QDs during the growth process. The quantum dots with larger size (CdSe-MSA) have the fluorescence spectra with broader bandwidth. The trend of the particles growth was discussed in details. Results revealed that the kind of capping agents are considerably influence on the nucleation as well as particle growth processes. [ABSTRACT FROM AUTHOR]

Spatial size tuning in the visual cortex has been considered as an important neuronal functional property for sensory perception. However, an analogous mechanism in the auditory system has remained controversial. In the present study, cell-attached recordings in the primary auditory cortex (A1) of awake mice revealed that excitatory neurons can be categorized into three types according to their bandwidth tuning profiles in response to band-passed noise (BPN) stimuli: nonmonotonic (NM), flat, and monotonic, with the latter two considered as non-tuned for bandwidth. The prevalence of bandwidth-tuned (i.e., NM) neurons increases significantly from layer 4 to layer 2/3. With sequential cell-attached and whole-cell voltage-clamp recordings from the same neurons, we found that the bandwidth preference of excitatory neurons is largely determined by the excitatory synaptic input they receive, and that the bandwidth selectivity is further enhanced by flatly tuned inhibition observed in all cells. The latter can be attributed at least partially to the flat tuning of parvalbumin inhibitory neurons. The tuning of auditory cortical neurons for bandwidth of BPN may contribute to the processing of complex sounds., (© The Author(s) 2018. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.)

The use of nanopore biosensors is set to be extremely important in developing precise single molecule detectors and providing highly sensitive advanced analysis of biological molecules. The precise tailoring of nanopore size is a significant step toward achieving this, as it would allow for a nanopore to be tuned to a corresponding analyte. The work presented here details a methodology for selectively opening nanopores in real-time. The tunable nanopores on a quartz nanopipette platform are fabricated using the electroetching of a graphene-based membrane constructed from individual graphene nanoflakes (ø ∼30 nm). The device design allows for in situ opening of the graphene membrane, from fully closed to fully opened (ø ∼25 nm), a feature that has yet to be reported in the literature. The translocation of DNA is studied as the pore size is varied, allowing for subfeatures of DNA to be detected with slower DNA translocations at smaller pore sizes, and the ability to observe trends as the pore is opened. This approach opens the door to creating a device that can be target to detect specific analytes.