Rapid advances in neurotechnology enable bidirectional communication between the nervous system and engineered devices. The precise recording and stimulation of typical target neurons by neural ...interfaces with adequate materials and structures can provide revolutionized medical applications, including the diagnosis and treatment of neurological disorders. Thereby, a proper understanding of the electronic device and its interfacing biological surroundings is necessary. Here, this review highlights the basic concepts of neural signaling, neural recording, and stimulation to help understand neural interfaces. Then, we summarize the considerations of the materials and introduce a variety of materials that satisfy the requirements. Furthermore, the key challenges for next-generation neural interfaces are considered, and future directions are explored based on recent studies.
We report a simple scheme to fabricate organic/inorganic hybrid nanostructures with extraordinary morphologies by one‐step spin coating, using a PS‐b‐PEO diblock copolymer as template coupled with ...sol‐gel chemistry. The shape and size of the titania nanoobject can be fine‐tuned by controlling the amount of sol‐gel precursor relative to PS‐b‐PEO and the composition of the precursor. Ordered arrays of nanoscopic titania objects such as nanodots, nanobowls, and nanonetworks were obtained from the initial hybrid nanostructures by removing the organic matrix by UV treatment. Photocatalytic activities of the resulting titania nanoobjects were investigated in terms of the degradation of a typical dye.
There are a few thousand abandoned metal mines in South Korea. The abandoned mines cause several environmental problems including releasing acid mine drainage (AMD), which contain a very high acidity ...and heavy metal ions such as Fe, Cu, Cd, Pb, and As. Iron oxides can be formed from the AMD by increasing the solution pH and inducing precipitation. Current study focused on the formation of iron oxide in an AMD and used the oxide for adsorption of heavy metals. The heavy metal adsorbed iron oxide was separated with a superconducting magnet. The duration of iron oxide formation affected on the type of mineral and the degree of magnetization. The removal rate of heavy metal by the adsorption process with the formed iron oxide was highly dependent on the type of iron oxide and the solution pH. A high gradient magnetic separation (HGMS) system successfully separated the iron oxide and harmful heavy metals.
Ordered arrays of Au or Ag nanoparticles supported on two-dimensional graphitic carbon films were prepared by direct carbonization of stabilized asymmetric polystyrene-
block-poly(4-vinyl pyridine) ...(PS-
b-P4VP) inverse micellar films loaded with metal precursors. Crosslinked PS-
b-P4VP thin film templates with metal precursors selectively distributed in P4VP domains were converted to carbonaceous thin films having well-defined, highly dispersed metal nanoparticle (NP) arrays by ultraviolet (UV) irradiation under vacuum and subsequent carbonization. Mesoporous carbon films were also obtained after extracting the metal NPs by sonication in selected solvents. PS-
b-P4VP was employed not only as carbon source, but also as template for introducing metal NPs in a nanopatterned configuration. The characteristic features and properties of thus generated hybrid carbon nanostructures were investigated by microscopy, UV–visible spectroscopy, X-ray photoelectron spectroscopy, X-ray diffraction measurement, and Raman spectroscopy.
In this study, we have proposed the auxiliary bias pulse scheme to improve the stability of atmospheric pressure plasma jets driven by an AC sinusoidal waveform excitation source. The stability of ...discharges can be significantly improved by the compensation of irregular variation in memory voltage due to the effect of auxiliary bias pulse. From the parametric study, such as the width, voltage, and onset time of auxiliary bias pulse, it has been demonstrated that the auxiliary bias pulse plays a significant role in suppressing the irregular discharges caused by the irregular variation in memory voltage and stable discharge can be initiated with the termination of the auxiliary bias pulse. As a result of further investigating the effects of the auxiliary pulse scheme on the jet stability under various process conditions such as the distance between the jet head and the counter electrode, and carrier gas flow, the jet stability can be improved by adjusting the amplitude and number of the bias pulse depending on the variations in the process conditions.
Purpose Through a study of rotavirus gastroenteritis (RVGE) cases experienced over 20 years at our center, we aimed to investigate changes in the ratio of rotavirus-associated benign convulsions with ...mild gastroenteritis (RaCwG) to RVGE and in patients’ demographics after rotavirus vaccination. Methods We analyzed the data of patients aged ≤6 years who visited Inha University Hospital between January 1999 and December 2019 and were confirmed to have RVGE. Patients were divided according to whether they had convulsions with mild gastroenteritis, and their demographics were compared. The yearly and monthly ratios of RaCwG to RVGE were evaluated. To investigate the effects of rotavirus vaccination, data regarding demographics and prevalence were divided into periods I (pre-vaccination, 1999–2009) and II (post-vaccination, 2010–2019) and compared. Results Altogether, 2,100 children had RVGE, and 50 (2.4%) had RaCwG. RaCwG occurred frequently every 4 to 6 years. Although the total number of RVGE and RaCwG cases significantly decreased in period II versus period I, the ratio of RaCwG to RVGE did not differ between the two groups (P=0.921). The age distribution shifted upwards in period II versus period I (P=0.001), but the sex ratio and seasonal distribution showed no significant difference. Conclusion Considering that the ratio of RaCwG to RVGE is dynamic, an increase in the ratio of RaCwG may be possible in the future. Although there was no change in the ratio of RaCwG to RVGE, the number of RVGE and RaCwG patients decreased simultaneously, suggesting that rotavirus vaccination was effective in preventing RaCwG.
To utilize propulsion energy effectively, it is necessary to develop technology that can enable variable thrust by altering the area of the nozzle throat in a solid rocket motor in real time. In this ...study, an aerospike-shaped pintle nozzle, an altitude compensation nozzle technology, was designed to improve the performance compared to that of the existing pintle nozzles. Pressure fluctuations caused by the movement of the pintle led to the hysteresis of the combustion chamber pressure, which sharply increased the pintle load. Depending on the design conditions of the actuator, a load that was approximately 2.5 times larger than that in the normal state could be applied to the actuator. Additionally, cold flow tests were conducted under static conditions to verify the reliability of the design code for the actuator load prediction results. Moreover, firing tests were performed to verify the reliability of the internal ballistic simulation code. Finally, factors related to the thermal expansion of the pintle and the deformation of the nozzle throat, which caused changes in the nozzle throat area during combustion, were identified and mathematically modeled. Additional firing tests were conducted to validate the updated numerical model. Before the model was updated, a pressure difference occurred at most three times or more between the performance prediction model and the firing test results, but the performance prediction error was reduced when the modified numerical analysis was used. If the present results are applied to a guided missile system, the high-altitude operation performance will improve and precision thrust control will become possible, enabling flexible guided missile system operation.
•An aerospike pintle nozzle for real-time rocket thrust control was developed.•Combustion chamber pressure hysteresis occurs due to pintle movement.•Factors that change the nozzle throat area were identified.•Dynamic performance prediction was achieved, and an analytic method was suggested.
The manuscript describes a novel method to fabricate a thin composite film based on spin coating in which surface plasmon bands of Au and Ag nanoparticles are effectively coupled with each other ...because of position-selective deposition of both nanoparticles on a self-assembled block copolymer structure. Simple solution blending and subsequent spin coating of Au nanoparticles (NPs) and a block copolymer micelles containing Ag NPs in the core regions offers a facile route for controlling coupled surface plasmon band (SPB) of the two NPs over 100 nm in wavelength in thin solid films. Effective coupling of two individual SPBs relies upon the self-assembled composite structure where Ag and Au NPs are preferentially located in the core and corona regions of the micelles, respectively, allowing not only a controlled interparticle distance but also homogeneous dispersion of the NPs throughout film.
Responsive composite gold nanofilms were fabricated by cooperative self-assembly of poly(4-vinylpyridine) grafted gold nanoparticles (Au NPs) and poly(4-vinylpyridine)-
b-polystyrene block ...copolymers.
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► Cooperative self-assembly of responsive Au NPs and block copolymers was demonstrated. ► Composite Au thin films consisting of PVP-hybridized Au NPs and PS-
b-PVP micelles were generated. ► Thin Au films have responsive surface plasmon resonance and morphology changes to vapor molecules.
Self-assembled poly(4-vinylpyridine)-grafted gold (Au) nanoparticles (NPs) and polystyrene-
b-poly(4-vinylpyridine) block copolymers were fabricated by the introduction of a selective solvent to a common solution. The assembled mixtures were spin-coated onto solid substrates to fabricate composite gold/polymer thin films composed of copolymer-hybridized Au NPs and independent copolymer micelles. The obtained composite Au thin films had variable localized surface plasmon resonance (LSPR) bands and microscopic morphologies upon vapor annealing with selective solvents because the adsorption and dissolving of solvent molecules into the films could rearrange the copolymer block. The hybrid nanostructured Au thin films may have potential in vapor sensing and organic assays.
We present evidence of denitrification on the continental slopes of the Ulleung Basin (UB) and the Eastern Japan Basin (EJB) near the Tatar Strait (TtS) in the East/Japan Sea (EJS), despite its high ...water column dissolved oxygen concentrations. Some nutrient concentration data deviate significantly from the fitted regression line of nitrate (N) vs. phosphate (P) in deep waters, indicating a loss of nitrate in the region. The EJS has a lower N/P ratio (ca. 12.4 below 300 dbar) than a traditional Redfield ratio (16). The N/P ratio and oxygen concentration are substantially lower at several locations whose depths are close to the sediment-water interface, near TtS (500 - 1100 dbar) and in UB (1100 - 2200 dbar). The decreased nitrate concentration is smaller than the expected nitrate level (a low N/P ratio of < 12.4), and a secondary nitrite peak near the bottom of these two regions: taken collectively, both indicate the presence of denitrification in the bottom layer. It is speculated that active re-mineralization and denitrification may occur simultaneously along the rich organic matter bottom layer on the slope environment. Denitrification rates are estimated at ~3 - 33 μmol N m-2 d-1. Current estimates do not support the previous idea of basin-wide denitrification in EJS, although the N/P ratio is low like in other hypoxic/anoxic seas. A better understanding of the denitrification process is necessary for predicting future changes of nitrogen cycle in the well-oxygenated EJS considering the decadal-scale physical and biogeochemical changes that have occurred.
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