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In this study, we successfully synthesized rare-earth-doped crystalline SrWO4 at room temperature by co-precipitation. The results from the X-ray diffraction analysis showed a main diffraction peak related to the (112) plane. Phosphors doped with either Dy3+ or Sm3+ ions showed strong light absorption in the UV region and blue-yellow and red light emission. To synthesize a white light phosphor, Dy3+ and Sm3+ ions were co-doped to produce a SrWO4:[Sm3+]/[Dy3+] phosphor. When the Sm3+ ion concentration was increased and the Dy3+ concentration was maintained, the red light intensity increased while the blue-yellow light intensity decreased. The composites were combined with polydimethylsiloxane (PDMS), and a flexible composite material was fabricated. The composite exhibited various luminescence properties under UV and visible light, which suggested its potential for use as an LED color filter.

A BaMoO4:[Er3+]/[Yb3+] up-conversion (UC) phosphor was synthesized by co-precipitation and calcination of the precursor at 800 °C. The main peak (112) for the synthesized phosphor was strongly detected in the XRD pattern and had a tetragonal structure. The doping of rare-earth ions affected the crystal lattice by shifting the main peak, decreasing the lattice constant, and shifting the position of the Raman signal. The synthesized upconverted phosphor exhibited strong green signals at 530 and 553 nm and weak red signals at 657 nm when excited at 980 nm. The green light emission intensity of the UC phosphor increased as the pump power of the laser increased due to the two-photon effect. The synthesized upconverted phosphor was prepared as a pellet and flexible composite. Thermal quenching led to a decrease in luminescence intensity as the temperature increased, which means that the phosphor can be applied to optical temperature sensing.

Due to the acceleration of global aging, many medical devices for elderly patients are emerging. Among them, hearing aids help patients with various noise hearing loss to overcome hearing loss, which is a typical geriatric disease, and to have normal daily life. However, if the hearing aid is not used by fitting the hearing aid according to the individual's hearing ability and characteristics, it can be used to overlook various side effects such as hearing loss and tinnitus. In addition, if noise and distortion occur due to the wrong use of hearing aids, damage to the hearing organs can be accumulated and consequently, hearing impairment can be accelerated. Therefore, this study aims to investigate the effects of hearing aids' noise and distortion on hearing ability and to study the characteristics of each device through performance experiments of hearing aids. The experimental results suggest the necessity of research to correct the side effects of hearing aids and to secure the safety of medical devices.

Herein, we confirm the performance difference according to the structure of self-assembling monolayer (SAM) and investigate the characteristics of the indium tin oxide (ITO) surface when ITO substrates are deposited by (3,3,3-trifluoropropyl)trimethoxysilane (F-3SAM) and (heptadecafluoro-1,1,2,2-tetrahydrodecyl)triethoxysilane (F-10SAM) having different chain lengths with trifluoromethyl group as terminal functional group, as well as SAM benzoic acid (BA) and 2-naphthoic acid (NA) with benzene ring forms. Through these, it is possible to control the wetting properties, surface roughness, and work function of the ITO surface. Wetting characteristics, average roughness, and changes in work function of the ITO surface were characterized by contact angle measurement, atomic force microscopy (AFM), and UV photoelectron spectroscopy (UPS). The measured contact angles were 41.1&deg, 82.25&deg, and 118&deg, for the bare ITO, NA, and F-10SAM, respectively, the average roughnesses of the SAM-modified surfaces were 1.377, 1.033, and 0.838 nm for the bare ITO, NA, and F-10SAM, respectively. The work function of the ITO surface modified with NA and F-10SAM increased from 0.21 and 0.36 eV to 5.01 and 5.16 eV, respectively. As a result, the surface properties of ITO were better for aliphatic SAM than for aromatic ring SAM.

We demonstrated a homeotropic liquid crystal (LC) alignment state on fluorinated self-assembled monolayers (FSAMs) deposited by gas-phase method as a function of deposition time. The gas-phase method to deposit FSAMs was simple process and cost-effective. Contact angle data and surface energy analyses of the FSAMs showed that film formation occurs, and showed a correlation with the homeotropic alignment of LC molecules on the FSAMs. Stable LC alignments on FSAMs were achieved at deposition time over 60 min. In addition, high transparency and thermal stability of FSAM further enhanced its possibility as a LC alignment layer.

In order to enhance the performance of organic light-emitting diodes, fluorinated self-assembled monolayer (F-SAM) with long alkyl chain was introduced to the device between the anode and hole-tran...

We propose a deep learning-based spike sorting method for extracellular recordings. For analysis of extracellular single unit activity, the process of detecting and classifying action potentials called &ldquo, spike sorting&rdquo, has become essential. This is achieved through distinguishing the morphological differences of the spikes from each neuron, which arises from the differences of the surrounding environment and characteristics of the neurons. However, cases of high structural similarity and noise make the task difficult. And for manual spike sorting, it requires professional knowledge along with extensive time cost and suffers from human bias. We propose a deep learning-based spike sorting method on extracellular recordings from a single electrode that is efficient, robust to noise, and accurate. In circumstances where labelled data does not exist, we created pseudo-labels through principal component analysis and K-means clustering to be used for multi-layer perceptron training and built high performing spike classification model. When tested, our model outperformed conventional methods by 2.1% on simulation data of various noise levels, by 6.0% on simulation data of various clusters count, and by 1.7% on in-vivo data. As a result, we showed that the deep learning-based classification can classify spikes from extracellular recordings, even showing high classification accuracy on spikes that are difficult even for manual classification.

A new Gadolinium Fine Aluminum Gallate (Ce:GFAG) scintillation crystal with both high energy resolution and fast timing properties has successfully been grown. Compared to Gd3Al2Ga3O12 (Ce:GAGG), this new inorganic scintillation crystal has a high luminosity similar to and a faster decay time. In this paper, we report on the timing and energy performance results of the new GFAG scintillation crystal read out with digital silicon photomultipliers (dSiPM) for positron emission tomography (PET) application. The best coincidence resolving time (FWHM) of polished 3×3×5 mm3 crystals was 223±6 ps for GFAG crystals compared to 396±28 ps for GAGG crystals and 131±3 ps for LYSO crystals respectively. An energy resolution (511 keV peak of Na-22) of 10.9±0.2% was attained with GFAG coupled to dSiPM after correcting for saturation effect, compared to 9.5±0.3% for Ce:GAGG crystals and 11.9±0.4% for LYSO crystals respectively. It is expected that this new scintillator may be competitive in terms of overall properties such as energy resolution, timing resolution and growing (raw material) cost, compared to existing scintillators for positron emission tomography (PET).

By using an electroless plating process with a Ni source solution including dimethylamine borane (DMAB) at pH 6.5 and 65 ◦ C, we obtained a higher purity Ni film (< 1 at.% boron) without damage to the anodized Al substrate. With increasing plating time, the thickness of the film increased gradually, although the average deposition rate of the Ni films decreased steadily. We can infer that the abrupt decrease in sheet resistance (Rs) at the interface region is due to the change in the boron concentration caused by surface reactions, and the gradual decrease in Rs in the bulk region is due mainly to the effect of the saturation of boron’s concentration on the thickness. From a boron-distribution viewpoint, this result indicates that the B concentration in the Ni film increases gradually with increasing plating time for plating times ≤ 60 s as a kind of initial stage (that is, interface region), and then saturates uniformly for plating times ≥ 300 s as a kind of bulk region. On the other hand, from an electronic structure viewpoint, this result implies that Ni gains 3d electrons with respect to elemental Ni. The increase in the number of electrons gained by the Ni 3d states may result in an enhancement of the electrical conductivity.

We examined the electro-optical characteristics of organic light emitting diodes according to the N,N'-diphenyl-N,N'-di(m-tolyl)-benzidine (TPD) thicknesses. The thicknesses of TPD were varied from 5 nm to 50 nm. The current density of the device with a TPD thickness of 5 nm was 8.94 times higher than that with a thickness of 50 nm at a driving voltage of 10 V. According to the conduction&ndash, current characteristics of conductors, the current densities improved with a decreasing TPD thickness. Different from the current density&ndash, voltage characteristics, the current efficiency&ndash, current density characteristics showed an improved efficiency with a 50 nm TPD thickness. The current efficiencies of a device with a 5 nm TPD thickness at a driving voltage of 10 V was 0.148 and at a 50 nm TPD thickness 0.993 cd/A, which was 6.7 times higher than the 5 nm TPD thickness. These results indicated that hole transport in Organic Light-Emitting Diode (OLED) devices were more efficient with thin 5 nm TPD than with thick 50 nm TPD, while electron transport was more efficient with thick 50 nm TPD, which caused conflicting results in the current efficiency-current density and current density-voltage characteristics according to TPD thicknesses.

In this study, we investigated the photoelectric effect and optimization of an organic light-emitting diode (OLED) depending on the presence or absence of a fluorinated self-assembled monolayer (FLSAM) and by varying the thickness of N,N'-Di (1-naphthyl)-N,N'-diphenyl-(1,1'-biphenyl)-4,4'-diamine (α-NPD) from 0 nm to 50 nm. The large distinction in electronegativity between the carbon and the fluorine replacing hydrogen in the alkyl chain of FLSAM generates a strong dipole moment to elevate the vacuum level, resulting in a change of the work function. This eliminates the injection barrier between the work function of the ITO modified by FLSAM and the highest occupied molecular orbital (HOMO) level of the hole-transport layer, thus leading to excellent driving voltage characteristics. Devices without FLSAM had a driving voltage more than twice that of devices using with FLSAM. The introduction of α-NPD as the hole-transport layer enhanced the electrical conductivity by facilitating the transport of holes. However, due to the inherent insulating film properties of α-NPD, the increase in its thickness resulted in a decrease in current density.

We report how the brain codes predatory threat information to guide and shape foraging behaviors in rats., Predation is considered a major selective pressure in the evolution of fear, but the neurophysiology of predator-induced fear is unknown. We simultaneously recorded lateral amygdala (LA) and prelimbic (PL) area neuronal activities as rats exited a safe nest to search for food in an open space before, during, and after encountering a “predator” robot programmed to surge from afar. Distinct populations of LA neurons transiently increased spiking as rats either advanced or fled the robot, whereas PL neurons showed longer-lasting spike trains that preceded and persisted beyond LA activity. Moreover, discrete LA-PL cell pairs displayed correlated firings only when the animals either approached or fled the robot. These results suggest a general fear function of the LA-PL circuit where the PL participates in the initial detection of potential threats, the LA signals the occurrence of real threats, and the dynamic LA-PL interaction optimizes defensive readiness for action.

The electrical characteristics of fluorinated self-assembled monolayers (FSAMs) in organic light-emitting diodes (OLEDs) were investigated according to the change in the lengths of their alkyl chains. As the number of fluorine atom increases, the device with long alkyl chain length allows the flow of a large amount of current because of the improved barrier height of the hole injection. However, the current efficiency under long alkyl chain length was decreased by the switched carrier balance. The device with the shortest FSAM alkyl chain length demonstrated an approximately 68% higher current efficiency than that with the longest alkyl chain length.

The characteristics of a Ag anode with molybdenum oxide (MoOx)-doped N,N′-bis(1-naphthyl)-N,N′-diphenyl-1,1′-diphenyl-1,4′-diamine (α-NPD) are reported. The current efficiency of devices with a Ag anode was achieved over 8.2 cd/A due to the microcavity effect. The current density of the device with a 25% concentration of MoOx was higher than those of a 10% concentration due to the improved charge transfer effect. The device of a Ag anode with a 25% concentration of MoOx indicated an approximate 227% higher current efficiency than that of an ITO anode with a 25% concentration of MoOx. The driving voltage of a Ag anode with a 25% concentration of MoOx was achieved at 4.4V with 10−2 A/cm2.

The electro-optics characteristics of organic light-emitting diodes (OLEDs) with microcavity effect were investigated. The transmittance of the substrate with Ag anode was lower than that of the indium-tin-oxide (ITO) anode due to the opaque characteristics of Ag. The current density of the device with Ag anode was high due to the low sheet resistance of Ag anode. The current efficiency of the device with Ag anode was high due to microcavity structure between Ag anode and Al cathode. Especially, the devices of Ag anode show over 43% higher current efficiency than that of conventional ITO anode. The low transmittance of Ag anode using microcavity effect realized as one kind of Fabry–Perot filters was also verified.

The electrical conductivity behavior of a fluorinated self-assembled monolayer (FSAM) of a molybdenum oxide (MoOx)-doped α-naphthyl diamine derivative (α-NPD) in organic light-emitting diodes (OLEDs) was investigated. The current density of the MoOx-doped α-NPD/FSAM device was proportional to its voltage owing to smooth carrier injection through the FSAM and the high carrier density of its bulk. The temperature-dependent characteristics of this device were investigated. The current density–voltage characteristics at different temperatures were almost the same owing to its very low activation energy. The activation energy of the device was estimated to be 1.056 × 10−2 [eV] and was very low due to the inelastic electron tunneling of FSAM molecules. Copyright © 2014 John Wiley & Sons, Ltd.

We report the electro-optical properties of an organic thin-film by varying the thickness of 1,4,5,8,9,11-hexaazatriphenylene-hexacarbonitrile (HAT(CN)6), included therein as an interlayer. Devices with HAT(CN)6, which are 7 nm thin films used as interlayers, exhibited good current density&ndash, voltage characteristics due to an improved hole injection barrier resulting from carrier ladder effects and carrier transport phenomena. The device without an interlayer showed the worst driving voltage characteristics due to the hole injection barrier. At low driving voltages, a device using 7 nm HAT(CN)6 as an interlayer exhibited a current density about 9.9 times higher than that of a device using 20 nm HAT(CN)6, and showed a current density about 9600 times higher than that of a device without an interlayer. Due to the proper carrier balance, the device using 7 nm HAT(CN)6 as an interlayer achieved a maximum current efficiency of 10.8 cd/A, which was the highest among the devices studied. This shows that the electro-optical properties of devices using HAT(CN)6 as an interlayer are dominated by the holes.

We investigate the effect of the interface phenomena of a self-assembled monolayer (SAM) molecules on hole injection. A SAM represents an easy and accurate approach to the modification of surface properties. The dipole moment of a fluorinated SAM (FSAM) improves hole injection from Indium Tin Oxide (ITO). We prepare several kinds of FSAM with different number of fluorine atoms FnSAM. As the number of fluorine atom increases, the dipole moment also increases. Increasing the chain length increases the van der Waals interaction between alkyl chains. We examine the interface characteristics of SAM molecules on the hole injection.

This study demonstrates the orientation characteristics of liquid crystals (LCs) on fluorinated self-assembled monolayers (FSAMs) deposited using the gas phase method. The authors confirmed that the FSAMs were properly deposited on indium-doped tin oxide glass substrates using x-ray photoelectron spectroscopy and atomic force microscopy. Compared with conventional polyimide (PI) layers, the authors confirmed that the FSAM is an alternative to the conventional PI layer. Regardless of the positive and negative LC characteristics, the LC molecules were vertically aligned on the FSAMs, with hydrophobic properties. In addition, an LC cell using an FSAM showed faster response times than that with a conventional PI layer when the electro-optical characteristics were examined. Therefore, these results indicate that FSAMs are suitable for LC applications as homeotropic LC alignment layers.

Summary Fear is an adaptive mechanism evolved to influence the primal decisions of foragers in "approach resource-avoid predator" conflicts [1–3]. To survive and reproduce, animals must attain the basic needs (food, water, shelter, and mate) while avoiding the ultimate cost of predation [4]. Consistent with this view, ecological studies have found that predatory threats cause animals to limit foraging to fewer places in their habitat and/or to restricted times [5–7]. However, the neurophysiological basis through which animals alter their foraging boundaries when confronted with danger remains largely unknown. Here, we investigated place cells in the hippocampus, implicated in processing spatial information and memory [8–10], in male Long-Evans rats foraging for food under risky situations that would be common in nature. Specifically, place cells from dorsal cornu ammonis field 1 (CA1) were recorded while rats searched for food in a semi-naturalistic apparatus (consisting of a nest and a relatively large open area) before, during, and after encountering a "predatory" robot situated remotely from the nest [11]. The looming robot induced remapping of place fields and increased the theta rhythm as the animals advanced toward the vicinity of threat, but not when they were around the safety of the nest. These neurophysiological effects on the hippocampus were prevented by lesioning of the amygdala. Based on these findings, we suggest that the amygdalar signaling of fear influences the stability of hippocampal place cells as a function of threat distance in rats foraging for food.

In this paper, the high-performance characteristics of a device that uses dipyrazino[2,3-f:2′,3′-h] quinoxaline-2,3 (HAT_CN) as the hole-injection layer are reported. Devices with HAT_CN showed a higher current density (of about 3.97 A/cm2 at 3 V) than those without a hole-injection layer. The higher current density of the devices with HAT_CN can be attributed to the nonexistence of a hole-injection barrier because of the HAT_CN, and the carrier transfer effect that is facilitated by the small difference between the lowest unoccupied molecular orbital and the highest occupied molecular orbital of the N,N′-Di(1-naphthyl)-N,N′-diphenyl-(1,1′-biphenyl)-4,4′-diamine in the hole-injection layer. The device with HAT_CN achieved a high maximum current efficiency of 11.45 cd/A, despite the collapse of the carrier balance. The external quantum efficiency of the device with HAT_CN was increased by approximately 0.4% compared to that of a device without the hole-injection layer.

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In this report, we discuss the effect of FSAM on both hole-injection and hole-transport functions. The thiophene derivative PEDOT:PSS is widely used as a hole-injection layer of conducting-polymer based LEDs (PLEDs). However, since PEDOT:PSS has some problems of strong acidity and metal cation impurities, a substitute material has been developed as a substitute. We used FSAM as a directly hole-injection layer of PLEDs and a single Alq3 layer. The introduction of FSAM lowered the driving voltage of devices and improved EL efficiency per current. In the former case, the EL properties of PLED with PEDOT:PSS is superior to those of PLED with FSAM. In the latter case, it was found the increase in hole injection contributed to high conduction of OLEDs. We reviewed the basic characteristics of polymer and OLED using FSAM.

We investigated the effects of using a Ag anode with the co-evaporation of molybdenum oxide (MoO x ) and N,N '-bis(1-naphthyl)-N,N '-diphenyl-1,1'-diphenyl-1,4'-diamine (α-NPD). The current density of the device with a Ag anode and a co-evaporation thin film was the highest among the various devices used owing to a low sheet resistance and charge transport. We discussed the mobility and carrier density of the co-evaporation thin film as compared with the electrical properties of the α-NPD thin film. The device with a Ag anode achieved high electroluminescence (EL) efficiency due to the optical design. In particular, the device with a Ag anode and a co-evaporation thin film showed an approximately 55% higher current efficiency than that with indium–tin oxide (ITO) and a MoO x layer.