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This study investigated the influence of gas-injected nanobubbles on the morphology of particles during spray drying under various experimental conditions. The nanoparticle tracking system was used to measure the generation, size, and concentration of nanobubbles. Experiments were conducted at different temperatures (160°C–260°C) and feed rates (0.2–0.26 g/s) to examine the effect of nanobubbles on spray drying and present diverse results. The deionized (DI) water with generated nanobubbles had a particle concentration of 1.8 × 108 particles/mL and a mean particle size of 242.6 nm, which was ∼3.31 × 107 particles/mL higher untreated DI water. The maltodextrin solution containing nanobubbles also showed a significant increase in particle generation, with a concentration of 1.62 × 109 particles/mL. The viscosity of the maltodextrin solution containing nanobubbles decreased by ∼18%, from 9.3 mPa·s to 7.5 mPa·s. Overall, the size of the generated particles was similar regardless of nanobubble treatment, but there was a tendency for particle size to increase under specific temperature (260°C) and feed flow rate (0.32 g/s) conditions. Furthermore, it was observed that the Hausner ratio significantly varied with increasing temperature and feed flow rate, and these results were explained through scanning electron microscopy images. These findings confirm that the gas nanobubbles mixed in the feed can exert diverse effects on the spray drying system and powder characteristics depending on the operating conditions. This study suggests that nanobubbles can contribute to a more efficient process in spray drying and can influence the morphological characteristics of particles depending on the spray drying conditions. [ABSTRACT FROM AUTHOR]

We derive the formulas for the resonance frequencies and their sensitivity when the nano-slit structures are used in the detection of thin layers. For a thin layer with a thickness of |$H$| deposited over the nanostructure, we show quantitatively that for both single and periodic slit structures with slit aperture size |$\delta $|⁠ , the sensitivity of resonance frequency reduces as |$H$| increases. Specifically, the sensitivity is of order |$O(\delta /H)$| if |$H>\delta $| and of order |$O(1+\ln H/\delta)$| otherwise. The evanescent wave modes are present along the interface between the thin dielectric film and ambient medium above. From the mathematical derivations, it is observed that the sensitivity of the resonance frequency highly depends on the effect of evanescent wave modes on the tiny slit apertures. [ABSTRACT FROM AUTHOR]

The present study was conducted to evaluate the total cooling effectiveness in combined full-coverage film cooling and impingement jet using an infrared thermographic technique. The effect of film cooling hole angle, blowing ratio, and height to diameter ratio between the film cooling and impingement jet plates was discussed. The total cooling effectiveness increased as impingement jet cooling was added. The angled film cooling holes had approximately 4.6% higher total cooling effectiveness than the normal film cooling holes. The total cooling effectiveness was almost constant regardless of height to diameter ratio, but enhanced as the blowing ratio was increased. [ABSTRACT FROM PUBLISHER]

Energy efficiency improvement in the industrial sector is critical in achieving carbon neutrality by 2050. A discrete-event-based dynamic energy simulation method is suggested to enhance the efficiency of energy-intensive manufacturing processes. The statistical characteristics of an actual manufacturing site were reflected in the simulation using data from the factory energy management system (FEMS) and manufacturing execution system (MES). The proposed method integrates discrete event simulation (DES) and transient thermal analysis. The dynamic behavior resulting from the interaction between sub-processes is simulated in DES. The energy conversion and detailed heat loss occurring at the facilities were modeled in the transient thermal analysis. The concept of process loss was suggested for the analysis to account for the energy that could have been not wasted at the factory level. The simulation results provided three key performance indicators (KPIs) representing the energy usage, production, and product quality of a manufacturing site. Investigation of these KPIs under various operating conditions found that the specific energy consumption could be reduced by 12.6% with a better operating strategy. We expect that the integrated simulation method can provide a practical solution for improving the energy efficiency of manufacturing sites equipped with a FEMS. • The dynamic behavior in energy usage of a manufacturing process is simulated. • Input modeling for the simulation is done using MES and EMS data of a real foundry. • The temperature history of the metal charge is predicted by the transient thermal model. • Process loss concept is suggested to consider factory-level energy efficiency. • SEC reduces by 12.6% while maintaining product quality through better operation. [ABSTRACT FROM AUTHOR]

Abstract: Symmetric bisimidazole and asymmetric imide-imidazole derivatives having a perylene structure were synthesized. Long, hyperbranched alkyl groups, attached to the benzimidazole moeity, enhanced the solubility of the imidazole derivatives. Soluble asymmetric imide-imidazoles were prepared using 1,2-diaminophenyls which contained methoxy, nitro and ester groups. The effects of both electron-withdrawing and donating groups were examined optically and electronically using both absorption and emission spectroscopy. Photoluminescence spectroscopy revealed that the various perylene derivatives displayed varying quantum yield; frontier orbital energy levels were determined using cyclic voltammetric analysis. The asymmetric imide-imidazole displayed the transient, electronic and optical properties of symmetric bisimide and symmetric bisimidazole perylene derivatives. Nitro derivation reduced the LUMO energy level of the asymmetric perylene by 0.05 eV while methoxy derivation increased it by 0.07 eV, in comparison with that of the unsubstituted, asymmetric perylene. Either bathochromic or hypsochromic spectral shifts of the asymmetric imidazoles were observed in solid film, depending on electronic substituent. [Copyright &y& Elsevier]

Abstract: Al–N-codoped ZnO films were fabricated by RF magnetron sputtering in the ambient of N2 and O2 on silicon (100) and homo-buffer layer, subsequently, annealed in O2 at low pressure. X-ray diffraction (XRD) spectra show that as-grown and 600°C annealed films grown by codoping method are prolonged along crystal c-axis. However, they are not prolonged in (001) plane vertical to c-axis. The films annealed at 800°C are not prolonged in any directions. Codoping makes ZnO films unidirectional variation. X-ray photoelectron spectroscopy (XPS) shows that Al content hardly varies and N escapes with increasing annealing temperature from 600°C to 800°C. [Copyright &y& Elsevier]

We have fabricated and demonstrated a new device called the vertical replacement-gate (VRG) MOSFET. This is the first MOSFET ever built in which: (1) all critical transistor dimensions are controlled precisely without lithography and dry etch, (2) the gate length is defined by a deposited film thickness, independently of lithography and etch, and (3) a high-quality gate oxide is grown on a single-crystal Si channel. In addition to this unique combination, the VRG-MOSFET includes self-aligned source/drain extensions (SDEs) formed by solid source diffusion (SSD), small parasitic overlap, junction, and source/drain capacitances, and a replacement-gate approach to enable alternative gate stacks. We have demonstrated nMOSFETs with an initial VRG process, and pMOSFETs with a more mature process. Since both sides of the device pillar drive in parallel, the drive current per μm of coded width can far exceed that of advanced planar MOSFETs. Our 100 nm VRG-pMOSFETs with tOX=25 A˚ drive 615 μA/μm at 1.5 V with IOFF=8 nA/μm—80% more drive than specified in the 1999 ITRS Roadmap at the same IOFF. Our 50 nm VRG-pMOSFETs with tOX=25 A˚ approach the 1.0 V roadmap target of ION=350 μA/μm at IOFF=20 nA/μm without the need for a hyperthin (<20 A˚) gate oxide. We have described a process for integrating n-channel and p-channel VRG-MOSFETs to form side-by-side CMOS that retains the key VRG advantages while providing packing density and process complexity that is competitive with traditional planar CMOS. All of this is achieved using current manufacturing methods, materials, and tools, and high-performance devices with 50 nm physical gate lengths (LG) have been demonstrated with precise gate length control without advanced lithography. [Copyright &y& Elsevier]

• A novel laboratory-scale experimental setup to measure changes in moisture content of textiles during drum drying. • A simple mathematical heat transfer model to assess moisture changes in drum drying. • Quantification of the impact of interfacial thermal contact resistance on drying time. Drum dryers are widely employed in various industrial fields for their remarkable capability to efficiently dry thin porous materials such as textiles and paper. The heat transfer process in drum drying involves an interaction between the drum surface and the materials being dried. However, measuring interfacial thermal contact conductance during drum drying is very challenging, and little data has been reported in the literature. It is therefore unclear how changes in interfacial thermal contact conductance quantitatively affect drum drying in terms of drying time. We created an innovative laboratory-scale experimental setup designed to measure changes in moisture content of textiles at various contact pressures during drum drying. By combining our experiments with a simple yet effective heat transfer model, we were able to quantify the impact of interfacial thermal contact resistance on drying time. Specifically, in drying tests using thin cotton textiles, the experimental results revealed that when the contact pressure was increased from 120 Pa to 480 Pa, the thermal contact conductance increased by approximately 30% and the drying time decreased by approximately 20%. The outcomes of our study significantly advance the current understanding of drum drying processes and reveal vital insights into techniques for optimizing energy consumption. [ABSTRACT FROM AUTHOR]

The ferroelectric properties of integrated Pt/SrBi[SUB2]Ta[SUB2]O[SUB9] (SBT)/Pt capacitors with boron (B)- and phosphorus (P)-doped silicate glass (BPSG) as an interlevel dielectric layer were investigated. After annealing at 800 °C to densify the BPSG, a significant reduction in remanent polarization was observed. Both transmission electron microscopy and nanoprobe energy dispersive spectroscopy analysis showed bismuth (Bi) and P interdiffusion across the interface between the SBT and BPSG layers. This strongly suggests that Pt/SBT/Pt capacitor degradation results from Bi loss in the surface region of the SBT layer, which is induced by P diffusion into the SBT. The degradation in ferroelectric properties was prevented by inserting a thin undoped silicate glass (USG) layer between the SBT and the BPSG, which blocked P diffusion. From the USG thickness dependence of the remanent polarization, P-induced degradation was also verified. [ABSTRACT FROM AUTHOR]

Background: A motor unit (MU) is formed by a single alpha motor neuron (MN) and the muscle fibers it innervates. The MU is essential for all voluntary movements. Functional deficits in the MU result in neuromuscular disorders (NMDs). The pathological mechanisms underlying most NMDs remain poorly understood, in part due to the lack of in vitro models that can comprehensively recapitulate multistage intercellular interactions and physiological function of the MU. Results: We have designed a novel three-dimensional (3D) bilayer hydrogel tri-culture system where architecturally organized MUs can form in vitro. A sequential co-culture procedure using the three cell types of a MU, MN, myoblast, and Schwann cell was designed to construct a co-differentiating tri-culture on a bilayer hydrogel matrix. We utilized a µ-molded hydrogel with an additional Matrigel layer to form the bilayer hydrogel device. The µ-molded hydrogel layer provides the topological cues for myoblast differentiation. The Matrigel layer, with embedded Schwann cells, not only separates the MNs from myoblasts but also provides a proper micro-environment for MU development. The completed model shows key MU features including an organized MU structure, myelinated nerves, aligned myotubes innervated on clustered neuromuscular junctions (NMJs), MN-driven myotube contractions, and increases in cytosolic Ca2+ upon stimulation. Conclusions: This organized and functional in vitro MU model provides an opportunity to study pathological events involved in NMDs and peripheral neuropathies, and can serve as a platform for physiological and pharmacological studies such as modeling and drug screening. Technically, the rational of this 3D bilayer hydrogel co-culture system exploits multiple distinct properties of hydrogels, facilitating effective and efficient co-culturing of diverse cell types for tissue engineering. [ABSTRACT FROM AUTHOR]

The thermal stress effects of the inter-level dielectric (ILD) layer on the ferroelectric performance of integrated Pt/SrBi[sub 2]Ta[sub 2]O[sub 9](SBT)/Pt capacitors were investigated. Two different thin film materials, pure SiO[sub 2] grown at 650 °C and B- and P-doped SiO[sub 2] grown at 400 °C by chemical vapor deposition techniques, were tested as an ILD layer. The ILD layer encapsulated the SBT capacitor array. During high temperature thermal cycling (up to 800 °C) after ILD deposition, which is used for both densifying the ILD and curing of the various damage imposed on the SBT capacitors, a large thermal stress occurred in the bottom Pt layer due to the thermal expansion mismatch between the various layers. In particular, the pure SiO[sub 2] ILD layer between the capacitors did not allow thermal expansion of the Pt layers, which led to a large accumulation of compressive stress in the layer. This resulted in hillock formation in the bottom Pt layer and eventual capacitor failure. However, the B- and P-doped SiO[sub 2] ILD layer contracted during thermal cycling by removing residual impurities, which allowed greater expansion of the Pt layer. Therefore, compressive stress accumulation did not occur and excellent ferroelectric properties were thus obtained from the integrated capacitor array. © 2001 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Near-infrared (NIR) curing recently became viable for the rapid curing of coating layers in several industries that require much faster line speeds to both increase production and reduce the system size, thereby saving on the overall curing cost. Previous works have revealed how NIR penetrates and efficiently heats the coating layer on top of a steel substrate. Despite these great efforts, the industry still requires more experimental evidence, data collection and system optimization to replace conventional hot air dryers with NIR dryers in the near future. Hence, we aim to develop a highly efficient NIR heating module, investigate its basic performance and suggest its optimized operation for the coil coating industry. First, we design and develop a NIR dryer integrated with a heating module, conveyor and waste heat recirculation loop. Second, we investigate the dynamic temperature response of the targeted steel substrate for various optical properties of coatings, such as absorption, reflectance and transmittance. Third, the curing performance is also observed in the NIR dryer for different coatings and operating conditions. We then discuss why NIR heating alone cannot meet the successful curing of a coating on substrates in terms of surface adhesion and resistance testing. Finally, we suggest a robust and stable operation method that combines NIR and convective oven heating, which allows for successfully cured outputs. [ABSTRACT FROM AUTHOR]

Diagnostic tools for the detection of protein-misfolding diseases (i.e., proteopathies) are limited. Gold nanoparticles (AuNPs) facilitate sensitive diagnostic techniques via visual color change for the identification of a variety of targets. In parallel, recently developed quaking-induced conversion (QuIC) assays leverage protein-amplification and fluorescent signaling for the accurate detection of misfolded proteins. Here, we combine AuNP and QuIC technologies for the visual detection of amplified misfolded prion proteins from tissues of wild white-tailed deer infected with chronic wasting disease (CWD), a prion disease of cervids. Our newly developed assay, MN-QuIC, enables both naked-eye and light-absorbance measurements for detection of misfolded prions. MN-QuIC leverages basic laboratory equipment that is cost-effective and portable, thus facilitating real-time prion diagnostics across a variety of settings. In addition to laboratory-based tests, we deployed to a rural field-station in southeastern Minnesota and tested for CWD on site. We successfully demonstrated that MN-QuIC is functional in a non-traditional laboratory setting by performing a blinded analysis in the field and correctly identifying all CWD positive and CWD not-detected deer at the field site in 24 h, thus documenting the portability of the assay. White-tailed deer tissues used to validate MN-QuIC included medial retropharyngeal lymph nodes, parotid lymph nodes, and palatine tonsils. Importantly, all of the white-tailed deer (n = 63) were independently tested using ELISA, IHC, and/or RT-QuIC technologies and results secured with MN-QuIC were 95.7% and 100% consistent with these tests for positive and non-detected animals, respectively. We hypothesize that electrostatic forces help govern the AuNP/prion interactions and conclude that MN-QuIC has great potential for sensitive, field-deployable diagnostics for CWD, with future potential diagnostic applications for a variety of proteopathies. [ABSTRACT FROM AUTHOR]

We compare the dielectric functions of silver interfaces obtained via thermal evaporation with those obtained with template stripping. Ellipsometry measurements show that the smoother template-stripped surfaces exhibit effective dielectric functions with a more negative real component and a smaller imaginary component, implying higher conductivity and less energy loss, respectively. These results agree with the relation between dielectric function and surface roughness derived from combining the effective-medium model and the Drude-Lorentz model. The improvement in the effective dielectric properties shows that metallic films prepared via template stripping can be favorable for applications in electronics, nanophotonics, and plasmonics. [ABSTRACT FROM AUTHOR]

Enhanced optical transmission and surface plasmon resonant cavity effects are studied for subwavelength aperture arrays surrounded by rectangular-shaped Bragg mirrors. A circular nanohole array with a surrounding rectangular Bragg resonator exhibits the introduction of polarization-dependent enhanced optical transmission by constructive and destructive interference effects generated within the cavity. The feasibility for high-density packing of several individually distinct nanohole arrays is demonstrated by also using the Bragg mirrors to block surface plasmon interference between multiple such neighboring devices spaced 5 μm apart. [ABSTRACT FROM AUTHOR]

Precise measurements of the mobility anisotropy along high-symmetry crystal axes in black phosphorus (BP) MOSFETs are reported. Locally back-gated BP MOSFETs with 13-nm HfO2 dielectric and channel length ranging from 0.3 to 0.7 $\mu \text{m}$ are fabricated. A single BP flake of a uniform thickness is exfoliated and etched along armchair (AC) and zigzag (ZZ) crystal axes, and the orientations are confirmed using optical and transmission electron microscopy analyses. The hole and electron mobilities along each direction are extracted using the transfer length method. The AC-to-ZZ hole mobility ratio is found to increase from 1.4 (1.5) to 2.0 (2.9) as the sheet concentration increased from $5.1\times 10^{\textsf {11}}$ to $1.9\times 10^{\textsf {12}}$ cm−2 at room temperature (77 K). The room-temperature electron mobility anisotropy is found to be similar to that for holes with an AC-to-ZZ mobility ratio increasing from 1.4 to 2.1 from $5.1\times 10^{\textsf {11}}$ to $1.9\times 10^{\textsf {12}}$ cm−2 though electrons showed only a very weak temperature dependence. A Boltzmann transport model is used to explain the concentration- and temperature-dependent mobility anisotropies which can be well described using a charge center scattering model. [ABSTRACT FROM AUTHOR]

We present periodic nanohole arrays fabricated in free-standing metal-coated nitride films as a platform for trapping and analyzing single organelles. When a microliter-scale droplet containing mitochondria is dispensed above the nanohole array, the combination of evaporation and capillary flow directs individual mitochondria to the nanoholes. Mammalian mitochondria arrays were rapidly formed on chip using this technique without any surface modification steps, microfluidic interconnects, or external power sources. The trapped mitochondria were depolarized on chip using an ionophore with results showing that the organelle viability and behavior were preserved during the on-chip assembly process. Fluorescence signal related to mitochondrial membrane potential was obtained from single mitochondria trapped in individual nanoholes revealing statistical differences between the behavior of polarized vs depolarized mammalian mitochondria. This technique provides a fast and stable route for droplet-based directed localization of organelles-on-a-chip with minimal limitations and complexity, as well as promotes integration with other optical or electrochemical detection techniques. [ABSTRACT FROM AUTHOR]

Nanopipettes are an attractive single-molecule tool for identification and characterisation of nucleic acids and proteins in solutions. They enable label-free analysis and reveal individual molecular properties, which are generally masked by ensemble averaging. Having control over the pore dimensions is vital to ensure that the dimensions of the molecules being probed match those of the pore for optimization of the signal to noise. Although nanopipettes are simple and easy to fabricate, challenges exist, especially when compared to more conventional solid-state analogues. For example, a sub-20 nm pore diameter can be difficult to fabricate and the batch-to-batch reproducibility is often poor. To improve on this limitation, atomic layer deposition (ALD) is used to deposit ultrathin layers of alumina (Al2O3) on the surface of the quartz nanopipettes enabling sub-nm tuning of the pore dimensions. Here, Al2O3 with a thickness of 8, 14 and 17 nm was deposited onto pipettes with a starting pore diameter of 75 ± 5 nm whilst a second batch had 5 and 8 nm Al2O3 deposited with a starting pore diameter of 25 ± 3 nm respectively. This highly conformal process coats both the inner and outer surfaces of pipettes and resulted in the fabrication of pore diameters as low as 7.5 nm. We show that Al2O3 modified pores do not interfere with the sensing ability of the nanopipettes and can be used for high signal-to-noise DNA detection. ALD provides a quick and efficient (batch processing) for fine-tuning nanopipettes for a broad range of applications including the detection of small biomolecules like RNA, aptamers and DNA–protein interactions at the single molecule level. [ABSTRACT FROM AUTHOR]

We examined groundwater and stream water interaction in the Inbuk stream, Korea, using various approaches including hydrologic, thermal, hydrochemical, and isotopic methods. For this purpose, we installed four piezometers (IYHW1-4) in the streambed at 10 m interval across the stream and at depths of 0.90 to 1.54 m. We monitored water levels and water temperatures every hour using automatic transducers at the piezometers and in the stream (IYSW1) from September 2013 to April 2014. We also analyzed chemical and isotopic compositions for the hyporheic waters, stream water, and nearby groundwater in early September and late November in 2013. The water levels and hydraulic gradients revealed that three (IYHW1, 2, and 4) of the piezometers were in upwelling conditions for most of the monitoring period, except for the earliest short period (considered to be the wet season), whereas one piezometer (IYHW3) showed a reverse behavior, indicating that the gaining was dominant in the dry period. The mean calculated influx to the stream was 3.04 × 10 cm/sec. Observed temperatures of stream water, hyporheic waters, and groundwater also revealed that stream water was downwelling in the early monitoring period (wet season), whereas the groundwater was generally upwelling in most of the resting period, which is consistent with the water level interpretation. Chemical composition analysis indicated that most of the waters were Ca-HCO type for both seasons. However, no distinctive difference between chemical compositions of water without substantial seasonal variation negated any inference on the flow conditions. The mixing ratios computed from oxygen and hydrogen isotopic compositions indicated that losing conditions were dominant in the wet season, whereas gaining conditions prevailed in the dry season. The interpretations of stream water and groundwater interactions based on these different methods are relatively consistent for this study area, indicating that such combined methods will be very useful in enhancing understanding of groundwater and stream water interaction. [ABSTRACT FROM AUTHOR]

High carrier mobility and tunability in graphene enable fundamental studies for plasmonics and various applications. Despite its versatility, however, single‐layer graphene (SLG) suffers from poor coupling efficiency to electromagnetic waves, presenting a major challenge for photonic applications. Compared with visible or infrared radiation, terahertz (THz) waves exhibit higher absorption in SLG due to Drude‐like intraband transitions, but the wavelength‐to‐SLG size mismatch becomes even more dramatic. Here, we experimentally demonstrate 99% extinction of THz wave transmission when SLG covers the openings of 2‐nm‐wide (≈λ/1 000 000) slits through a metal film. By resonantly coupling THz waves through annular nanogaps, the extremely localized fields lead to near‐perfect extinction and strong absorption in SLG. Atomic‐layer lithography is used to produce these nanometer‐wide, millimeter‐long gaps over an entire 4‐in. wafer. Furthermore, by integrating these devices with an ionic liquid, enhanced intraband absorption in the SLG leads to 80% modulation of THz waves with an operational voltage as low as 1.5 V. [ABSTRACT FROM AUTHOR]

We have combinedatomic layer lithography and template stripping to produce a new classof substrates for surface-enhanced infrared absorption (SEIRA) spectroscopy.Our structure consists of a buried and U-shaped metal–insulator–metalwaveguide whose folded vertical arms efficiently couple normally incidentlight. The insulator is formed by atomic layer deposition (ALD) ofAl2O3and precisely defines the gap size. Theburied nanocavities are protected from contamination by a silicontemplate until ready for use and exposed by template stripping ondemand. The exposed nanocavity generates strong infrared resonances,tightly confines infrared radiation into a gap that is as small as3 nm (λ/3300), and creates a dense array of millimeter-longhotspots. After partial removal of the insulators, the gaps are backfilledwith benzenethiol molecules, generating distinct Fano resonances dueto strong coupling with gap plasmons, and a SEIRA enhancement factorof 105is observed for a 3 nm gap. Because of the wafer-scalemanufacturability, single-digit-nanometer control of the gap sizevia ALD, and long-term storage enabled by template stripping, ourburied plasmonic nanocavity substrates will benefit broad applicationsin sensing and spectroscopy. [ABSTRACT FROM AUTHOR]

Wepresent metallic nanohole arrays fabricated on suspended membranesas an optofluidic substrate. Millimeter-sized suspended nanohole arrayswere fabricated using nanoimprint lithography. We demonstrate refractive-index-basedtuning of the optical spectra using a sucrose solution for the optimizationof SERS signal intensity, leading to a Raman enhancement factor of107. Furthermore, compared to dead-ended nanohole arrays,suspended nanohole arrays capable of flow-through detection increasedthe measured SERS signal intensity by 50 times. For directed transportof analytes, we present a novel methodology utilizing surface tensionto generate spontaneous flow through the nanoholes with flow ratesof 1 μL/min, obviating the need for external pumps or microfluidicinterconnects. Using this method for SERS, we obtained a 50 timeshigher signal as compared to diffusion-limited transport and coulddetect 100 pM 4-mercaptopyridine. The suspended nanohole substratespresented herein possess a uniform and reproducible geometry and showthe potential for improved analyte transport and SERS detection. [ABSTRACT FROM AUTHOR]

We experimentally demonstrate dielectrophoreticconcentration ofbiological analytes on the surface of a gold nanohole array, whichconcurrently acts as a nanoplasmonic sensor and gradient force generator.The combination of nanohole-enhanced dielectrophoresis, electroosmosis,and extraordinary optical transmission through the periodic gold nanoholearray enables real-time label-free detection of analyte moleculesin a 5 μL droplet using concentrations as low as 1 pM withina few minutes, which is more than 1000 times faster than purely diffusion-basedbinding. The nanohole-based optofluidic platform demonstrated hereis straightforward to construct, applicable to both charged and neutralmolecules, and performs a novel function that cannot be accomplishedusing conventional surface plasmon resonance sensors. [ABSTRACT FROM AUTHOR]

Surface-based sensors that rely ondiffusion for transport of targetmolecules to the sensor surface can lead to long and sometimes impracticaldetection time for low analyte concentrations. Here we describe anew method for rapid in situ SERS detection of ultralow subpicomolarconcentration of the analyte molecules. The method is based upon adynamic dielectrophoresis-enabled assembly of metal nanoparticlesin the form of pearl chains with nanometer-sized gaps. We demonstratein situ SERS measurement of benzenethiol in less than 2 min withoutthe requirement of long incubation times. This approach is then extendedto detect the biological analyte, adenine, at femtomolar concentrationsin a short time from a 2 μL sample droplet. [ABSTRACT FROM AUTHOR]

The ability to precisely control the topography, roughness, and chemical properties of metallic nanostructures is crucial for applications in plasmonics, nanofluidics, electronics, and biosensing. Here a simple method to produce embedded nanoplasmonic devices that can generate tunable plasmonic fields on ultraflat surfaces is demonstrated. Using a template-stripping technique, isolated metallic nanodisks and wires are embedded in optical epoxy, which is capped with a thin silica overlayer using atomic layer deposition. The top silica surface is topographically flat and laterally homogeneous, providing a uniform, high-quality biocompatible substrate, while the nanoplasmonic architecture hidden underneath creates a tunable plasmonic landscape for optical imaging and sensing. The localized surface plasmon resonance of gold nanodisks embedded underneath flat silica films is used for real-time kinetic sensing of the formation of a supported lipid bilayer and subsequent receptor-ligand binding. Gold nanodisks can also be embedded in elastomeric materials, which can be peeled off the substrate to create flexible plasmonic membranes that conform to non-planar surfaces. [ABSTRACT FROM AUTHOR]

Wedemonstrate a novel scheme for plasmonic nanofocusing with internallyilluminated asymmetric metallic pyramidal tips using linearly polarizedlight. A wafer-scale array of sharp metallic pyramids is fabricatedvia template stripping with films of different thicknesses on opposingpyramid facets. This structural asymmetry is achieved through a one-stepangled metal deposition that does not require any additional lithographyprocessing and when internally illuminated enables the generationof plasmons using a Kretschmann-like coupling method on only one sideof the pyramids. Plasmons traveling toward the tip on one side willconverge at the apex, forming a nanoscale “hotspot.”The asymmetry is necessary for these focusing effects since symmetricpyramids display destructive plasmon interference at the tip. Computersimulations confirm that internal illumination with linearly polarizedlight at normal incidence on these asymmetric pyramids will focusoptical energy into nanoscale volumes. Far-field optical experimentsdemonstrate large field enhancements as well as angle-dependent spectraltuning of the reradiated light. Because of the low background lightlevels, wafer-scale fabrication, and a straightforward excitationscheme, these asymmetric pyramidal tips will find applications innear-field optical microscopy and array-based optical trapping. [ABSTRACT FROM AUTHOR]

Solid-state quantum emitters, suchas artificially engineered quantumdots or naturally occurring defects in solids, are being investigatedfor applications ranging from quantum information science and optoelectronicsto biomedical imaging. Recently, these same systems have also beenstudied from the perspective of nanoscale metrology. In this letter,we study the near-field optical properties of a diamond nanocrystalhosting a single nitrogen vacancy center. We find that the nitrogenvacancy center is a sensitive probe of the surrounding electromagneticmode structure. We exploit this sensitivity to demonstrate nanoscalefluorescence lifetime imaging microscopy (FLIM) with a single nitrogenvacancy center by imaging the local density of states of an opticalantenna. [ABSTRACT FROM AUTHOR]

Matrix molecules convey biochemical and physical guiding signals to neurons in the central nervous system (CNS) and shape the trajectory of neuronal fibers that constitute neural networks. We have developed recombinant human IgMs that bind to epitopes on neural cells, with the aim of treating neurological diseases. Here we test the hypothesis that recombinant human IgMs (rHIgM) can guide neurite outgrowth of CNS neurons. Microcontact printing was employed to pattern rHIgM12 and rHIgM22, antibodies that were bioengineered to have variable regions capable of binding to neurons or oligodendrocytes, respectively. rHIgM12 promoted neuronal attachment and guided outgrowth of neurites from hippocampal neurons. Processes from spinal neurons followed grid patterns of rHIgM12 and formed a physical network. Comparison between rHIgM12 and rHIgM22 suggested the biochemistry that facilitates anchoring the neuronal surfaces is a prerequisite for the function of IgM, and spatial properties cooperate in guiding the assembly of neuronal networks [ABSTRACT FROM AUTHOR]

Nanofabricated metallic tips are at the core of important research in single-molecule imaging, near-field scanning optical microscopy, tip-enhanced Raman spectroscopy, as well as potential commercial applications such as heat-assisted magnetic recording. While challenging to fabricate, much progress has been made towards the reliable production of extremely sharp (10 nm) metallic probes. In this review, the various factors that go into the design of metallic tips, their fabrication, packaging and system integration, characterization, passivation, and eventual use are discussed. Fabrication challenges, implementation issues, optical excitation schemes, and various current and emerging applications are also discussed. For the rapidly emerging fields of plasmonics and nanophotonics, the use of sharp metallic tips has generated significant scientific progress and will play an integral role well into the future. [ABSTRACT FROM AUTHOR]

In metal optics gold assumes a special status because of its practical importance in optoelectronic and nano- optical devices, and its role as a model system for the study of the elementary electronic excitations that underlie the interaction of electromagnetic fields with metals. However, largely inconsistent values for the frequency dependence of the dielectric function describing the optical response of gold are found in the literature. We performed precise spectroscopic ellipsometry measurements on evaporated gold, template-stripped gold, and single-crystal gold to determine the optical dielectric function across a broad spectral range from 300 nm to 25 μm (0.05-4.14 eV) with high spectral resolution. We fit the data to the Drude free-electron model, with an electron relaxation time τD = 14 ± 3 fs and plasma energy ħωp = 8.45 eV. We find that the variation in dielectric functions for the different types of samples is small compared to the range of values reported in the literature. Our values, however, are comparable to the aggregate mean of the collection of previous measurements from over the past six decades. This suggests that although some variation can be attributed to surface morphology, the past measurements using different approaches seem to have been plagued more by systematic errors than previously assumed. [ABSTRACT FROM AUTHOR]

Metallic nanostructures now play an important role in many applications. In particular, for the emerging fields of plasmonics and nanophotonics, the ability to engineer metals on nanometric scales allows the development of new devices and the study of exciting physics. This review focuses on top-down nanofabrication techniques for engineering metallic nanostructures, along with computational and experimental characterization techniques. A variety of current and emerging applications are also covered. [ABSTRACT FROM AUTHOR]

We have investigated the retention characteristics of ferroelectric random access memories (FeRAMs) using a bismuth layered perovskite, (Bi,La)4Ti3O12 (BLT). Due to the charge retention loss in ferroelectric storage capacitors, the sensing signal margin in FeRAM devices decreases from 920 mV at the retention time of 0.01 s to 770 mV at 100 s. From the logarithmic time dependence of the loss of obtained cell signals, the average margin of 520 mV is expected to remain after 10 y at 90°C. In addition, the slower retention loss rate in ferroelectric capacitors in long time retention region, suggests the high device reliability against retention degradation. [ABSTRACT FROM AUTHOR]

Highlights • Electrodes with 20 nm-wide gaps were fabricated by atomic layer lithography. • Nanogap electrodes enable low-voltage dielectrophoresis (DEP) trapping. • Spherical supported lipid bilayers and myelin particles were trapped with DEP. • Integrated microfluidics allow buffer switching and reagent delivery for binding assays. We demonstrate a gold nanogap electrode platform that can rapidly create a linear array of biological particles by low-voltage dielectrophoresis (DEP). We further combine microfluidic buffer exchange to introduce protein molecules in high-conductivity solutions while trapping and immobilizing particles. The nanogap between the gold electrodes enables low operating voltages that prevent unwanted Joule heating in high-conductivity buffers. This platform is used to trap bioparticles composed of lipid membranes such as spherical supported lipid bilayers and brain-derived myelin particles, followed by detection of protein binding to specific membrane-bound receptors. We use bioparticles with different sizes, physicochemical properties, and origins to demonstrate a platform that can be used to study a variety of biomolecular interactions. The low-power linear DEP trap combined with microfluidic buffer exchange has potential to enable a portable biosensing platform to rapidly concentrate rare biological particles and perform on-chip binding assays with improved detection limits in physiological buffers. [ABSTRACT FROM AUTHOR]

We investigate thin Ag films incorporating plasmonic nanohole arrays as transparent conducting electrodes for organic photovoltaic cells. Plasmonic electrodes are fabricated using nanosphere lithography to create hexagonal nanohole arrays over centimeter-sized areas. Devices constructed using a nanopatterned Ag anode show power conversion efficiencies that exceed those of devices constructed on conventional indium-tin-oxide, independent of light polarization. In comparison to cells constructed on unpatterned Ag, the power conversion efficiency is noted to double with patterning. [ABSTRACT FROM AUTHOR]

The authors report a combination of the enhanced transmission effect and shape resonances in a periodic array of nanoscale double-hole structures in a gold film to enhance the detection sensitivity of surface plasmon biosensors. Finite-difference time-domain calculations are used to quantify field enhancement at the apexes of the double-hole structure. The double-hole array was used to measure the formation of a self-assembled monolayer and for real-time sensing of protein adsorption onto a gold surface. This result demonstrates the potential to integrate propagating surface plasmons and localized shape resonances to improve real-time biosensors. [ABSTRACT FROM AUTHOR]

A label-free, non-dispruptive, and real-time analytical device to monitor the dynamic features of biomolecules and their interactions with neighboring molecules is an essential prerequisite for biochip- and diagonostic assays. To explore one of the central questions on the lipid-lipid interactions in the course of the liquid-ordered (l o) domain formation, called rafts, we developed a method of reconstituting continuous but spatially heterogeneous lipid membrane platforms with molayer-bilayer juntions (MBJs) that enable to form the l o domains in a spatiotemporally controlled manner. This allows us to detect the time-lapse dynamics of the lipid-lipid interactions during raft formation and resultant membrane phase changes together with the raft-associated receptor-ligand binding through the surface plasmon resonance (SPR). For cross-validation, using epifluorescence microscopy, we demonstrated the underlying mechanisms for raft formations that the infiltration of cholesterols into the sphingolipid-enriched domains plays a crucial roles in the membrane phase-separation. Our membrane platform, being capable of monitoring dynamic interactions among lipids and performing the systematic optical analysis, will unveil physiological roles of cholesterols in a variety of biological events. Continuous but spatially heterogeneous membranes were probed by the SPR for monitoring the kinetic behavior of lipid-lipid interactions (a) and the accompanying biochemical activity of ligand-receptor binding. Our monolayer-bilayer junction methodology of manipulating the bio-membranes enables to precisely control the phase-separation of l o domains at pre-defined regions (b) on a SPR-based biochip and to unveil the kinetics of the raft formation together with raft-associated receptor-ligand interactions (c). Image 1 • Continuous but spatially heterogeneous membranes were probed by the SPR for monitoring the kinetic behavior of lipid-lipid interactions • The accompanying biochemical activity of ligand-receptor binding. Our monolayer-bilayer junction methodology of manipulating the bio-membranes enables to precisely control the phase-separation of l o domains at pre-defined regions on a SPR-based biochip and to unveil the kinetics of the raft formation together with raft-associated receptor-ligand interactions [ABSTRACT FROM AUTHOR]

On page 2812, Sang‐Hyun Oh and co‐workers report using template stripping to create embedded plasmonic nanodisks that can generate tunable plasmonic fields on ultraflat surfaces. The embedded nanodisks are topographically flat and capped with a silica layer to form a laterally homogeneous and biocompatible substrate. The nanoplasmonic architecture hidden underneath creates a tunable plasmonic landscape. Nanostructures can also be embedded in elastomeric materials, which can be peeled off the substrate to create flexible plasmonic membranes that conform to nonplanar surfaces. [ABSTRACT FROM AUTHOR]