Synthesis mechanism from graphene quantum dots to carbon nanotubes by ion-sputtering assisted chemical vapor deposition.

We present the first work of the synthesis mechanism from graphene quantum dots (GQDs) to carbon nanotubes (CNTs) by an ion-sputtering assisted chemical vapor deposition. During the annealing process, a Pt thin film deposited by the ion-sputtering was dewetted and agglomerated to form many nanometer-sized particles, leading to Pt nanoparticles (PtNPs) that can act as catalysts for creating carbon allotropes. The shape of the allotropes can be effectively tailored from GQDs to CNTs by controlling three key parameters such as the dose of catalytic ions (D), amounts of carbon source (S), and thermal energy (T). In our work, it was clearly proved that the growth control from GQDs to CNTs has a comparably proportional relationship with D and S, but has a reverse proportional relationship with T. Furthermore, high-purity GQDs without any other by-products and the CNTs with the cap of PtNPs were generated. Their shapes were appropriately controlled, respectively, based on the established synthesis mechanism.

Capacitorless One-Transistor Dynamic Random-Access Memory with Novel Mechanism: Self-Refreshing.

In this paper, we propose for the first time a self-refreshing mechanism in a junctionless field-effect transistor (JLFET) based on one-transistor dynamic random-access memory (1T-DRAM) with a silicon-on-insulator (SOI) structure. The self-refreshing mechanism continuously creates holes by appropriately generating impact ionization during the holding process through the application of an appropriate operation bias voltage. This leads to self-refreshing, which prevents the recombination of holes. When using the self-refreshing mechanism for the proposed device, the sensing margins were 15.4 and 12.7 µA/µm at 300 and 358 K, respectively. Moreover, the device achieved an excellent performance retention time of >500 ms, regardless of the temperature of the 1T-DRAM with a single gate. Furthermore, cell disturbance analysis and voltage optimization were performed to evaluate the in-cell reliability of the proposed device. It also showed excellent performance in terms of energy consumption and writing speed.

Molecular-level chemical composition of aerosol and its potential source tracking at Antarctic Peninsula.

Marine organic aerosols play crucial roles in global climatic systems. However, their chemical properties and relationships with various potential organic sources still need clarification. This study employed high-resolution mass spectrometry to investigate the identity, origin, and transportation of organic aerosols in pristine Antarctic environments (King Sejong Station; 62.2°S, 58.8°W), where complex ocean-cryosphere-atmosphere interactions occur. First, we classified the aerosol samples into three clusters based on their air mass transport history. Next, we investigated the relationship between organic aerosols and their potential sources, including organic matter dissolved in the open ocean, coastal waters, and runoff waters. Cluster 1 (C1), in which the aerosols mainly originated from the open ocean area (i.e., pelagic zone-influenced), exhibited a higher abundance of lipid-like and protein-like organic aerosols than cluster 3 (C3), with ratios 1.8- and 1.6-times higher, respectively. In contrast, C3, characterized by longer air mass retention over sea ice and land areas (i.e., inshore-influenced), had higher lignin- and condensed aromatic structures (CAS)-like organic aerosols by 2.2- and 3.4-times compared to C1. Cluster 2 (C2) has intermediate characteristics between C1 and C3 concerning the chemical properties of the aerosols and air mass travel history. Notably, the chemical properties of the aerosols assigned to C1 are closely related to those of phytoplankton-derived organics enriched in the open ocean. In contrast, those of C3 are comparable to those of terrestrial plant-derived organics enriched in coastal and runoff waters. These findings help evaluate the source-dependent properties of organic aerosols in changing Antarctic environment.

The effect of masks on the emotion perception of a facial crowd.

The present study investigated the effect of facial masks on people's ability to perceive emotions in crowds. We presented faces with the bottom halves occluded by masks or full faces without occlusion. In two sequentially presented crowds, we varied the number of faces, emotional valence, and intensity of facial expressions, examining the impact of masks on the perception of crowd emotion. Participants reported which of the two crowds they would avoid based on the crowds' average emotions. The participants' ability to judge the average emotion of a crowd, especially a crowd expressing happiness, was impaired when the crowd wore masks. For faces covered by masks, crowd emotion judgments were more negatively biased than those without masks. However, participants could still distinguish the emotional intensities of a crowd wearing masks above chance. Additionally, participants responded more quickly to a crowd with more people without compromising accuracy, despite the perceptual challenges imposed by facial masks. Our results suggest that under ambiguous social situations in which individuals' emotions are partially hidden by masks, a large group may provide stronger social cues than a small group, thereby promoting communication and regulating social behaviors.

Parameterization of below-cloud scavenging for polydisperse fine mode aerosols as a function of rain intensity.

The below-cloud aerosol scavenging process by precipitation is one of the most important mechanisms to remove aerosols from the atmosphere. Due to its complexity and dependence on both aerosol and raindrop sizes, wet scavenging process has been poorly treated, especially during the removal of fine particles. This makes the numerical simulation of below-cloud scavenging in large-scale aerosol models unrealistic. To consider the slip effects of submicron particles, a simplified expression for the diffusion scavenging was developed by approximating the Cunningham slip correction factor. The derived analytic solution was parameterized as a simple power function of rain intensity under the assumption of the lognormal size distribution of particles. The resultant approximated expression was compared to the observed data and the results of previous studies including a 3D atmospheric chemical transport model simulation. Compared with the default GEOS-Chem coefficient of 0.00106R0.61 and the observation-based coefficient of 0.0144R0.9268, the coefficient of a and b in Λm = aRb spread in the range of 0.0002- 0.1959 for a and 0.3261- 0.525 for b over a size distribution of GSD of 1.3-2.5 and a geometric mean diameter of 0.01- 2.5 µm. Overall, this study showed that the scavenging coefficient varies widely by orders of magnitude according to the size distribution of particles and rain intensity. This study also demonstrated that the obtained simplified expression could consider the theoretical approach of aerosol polydispersity. Our proposed analytic approach showed that results can be effectively applied for reduced computational burden in atmospheric modeling.

The complete mitochondrial genome of an Antarctic moss, Andreaea regularis Müll. Hal. 1890 (Andreaeaceae).

In the present study, we determined the complete mitochondrial genome of Andreaea regularis Müll. Hal. 1890, a lantern moss of the genus Andreaea Hedw. (Andreaeaceae). The A. regularis mitochondrial genome, with a total length of 118,833 bp, consists of 40 protein-coding genes, 3 ribosomal RNA genes, and 24 transfer RNA genes. A phylogenetic tree constructed with 19 complete mitochondrial genomes composed of liverworts, hornworts, and 15 mosses showed that Andreaeales formed the closest sister to Sphagnales before divergence of the remaining moss groups, indicating A. regularis being one of the earliest mosses. Our findings could be beneficial to investigate the bryophyte evolution.

Observational evidence linking ocean sulfur compounds to atmospheric dimethyl sulfide during Icelandic Sea phytoplankton blooms.

In two Icelandic Sea spring blooms (May 2018 and 2019) in the North Atlantic Ocean (62.9-68.0°N, 9.0-28.0°W), chlorophyll-a and dimethylsulfoniopropionate (DMSP) concentrations and DMSP lyase activity (the DMSP-to-dimethyl sulfide (DMS) conversion efficiency) were measured at 67 stations, and the hourly atmospheric DMS mixing ratios were concurrently measured only in May 2019 at Storhofdi on Heimaey Island, located south of Iceland (63.4°N, 20.3°W). The ocean parameters for biology (i.e., chlorophyll-a, DMSP, and DMSP lyase activity) were broadly associated in distribution; however, the statistical significance of the association differed among four ocean domains and also between 2018 and 2019. Specifically, the widespread dominance of Phaeocystis, coccolithophores, and dinoflagellates (all rich in DMSP and high in DMSP lyase activity) across the study area is a compelling indication that variations in DMSP-rich phytoplankton were likely a main cause of the variations in statistical significance. For all the ocean domains defined here, we found that the DMS production capacity (calculated using the exposures of air masses to ocean biology prior to their arrivals at Heimaey and the atmospheric DMS mixing ratios of those air masses at Heimaey) was surprisingly consistent with in situ ocean S data (i.e., DMSP and DMSP lyase activity). Our study shows that the proposed computational approach enabled the detection of changes in DMS production and emission in association with changes in ocean primary producers.

Ocean-atmosphere interactions: Different organic components across Pacific and Southern Oceans.

Sea spray aerosol (SSA) particles strongly influence clouds and climate but the potential impact of ocean microbiota on SSA fluxes is still a matter of active research. Here-by means of in situ ship-borne measurements-we explore simultaneously molecular-level chemical properties of organic matter (OM) in oceans, sea ice, and the ambient PM2.5 aerosols along a transect of 15,000 km from the western Pacific Ocean (36°13'N) to the Southern Ocean (75°15'S). By means of orbitrap mass spectrometry and optical characteristics, lignin-like material (24 ± 5 %) and humic material (57 ± 8 %) were found to dominate the pelagic Pacific Ocean surface, while intermediate conditions were observed in the Pacific-Southern Ocean waters. In the marine atmosphere, we found a gradient of features in the aerosol: lignin-like material (31 ± 9 %) dominating coastal areas and the pelagic Pacific Ocean, whereas lipid-like (23 ± 16 %) and protein-like (11 ± 10 %) OM controlled the sympagic Southern Ocean (sea ice-influence). The results of this study showed that the OM composition in the ocean, which changes with latitude, affects the OM in aerosol compositions in the atmosphere. This study highlights the importance of the global-scale OM monitoring of the close interaction between the ocean, sea ice, and the atmosphere. Sympagic primary marine aerosols in polar regions must be treated differently from other pelagic-type oceans.

Design of a Capacitorless DRAM Based on a Polycrystalline-Silicon Dual-Gate MOSFET with a Fin-Shaped Structure.

In this study, a capacitorless one-transistor dynamic random-access memory (1T-DRAM) cell based on a polycrystalline silicon dual-gate metal-oxide-semiconductor field-effect transistor with a fin-shaped structure was optimized and analyzed using technology computer-aided design simulation. The proposed 1T-DRAM demonstrated improved memory characteristics owing to the adoption of the fin-shaped structure on the side of gate 2. This was because the holes generated during the program operation were collected on the side of gate 2, allowing an expansion of the area where the holes were stored using the fin-shaped structure. Therefore, compared with other previously reported 1T-DRAM structures, the fin-shaped structure has a relatively high retention time due to the increased hole storage area. The proposed 1T-DRAM cell exhibited a sensing margin of 2.51 µA/µm and retention time of 598 ms at T = 358 K. The proposed 1T-DRAM has high retention time and chip density, so there is a possibility that it will replace DRAM installed in various applications such as PCs, mobile phones, and servers in the future.

The complete mitochondrial genome of the moss Neckeropsis nitidula (Mitt.) M. Fleisch.

In this study, the complete mitochondrial genome of Neckeropsis nitidula (Mitt.) M. Fleisch. in the family Neckeraceae was determined. This mitogenome was 104,716 base pairs in length and contained 40 protein-coding genes, three ribosomal RNA genes, and 24 transfer RNA genes. The overall nucleotide composition was asymmetric (29.5% A, 29.3% T, 21.3% G, and 19.9% C), with a 41.2% G + C content. The gene arrangement was identical to that of most Hypnales genomes. A phylogenetic tree was constructed using the N. nitidula mitogenome obtained in this study and the complete mitochondrial genome sequences of 23 bryophytes and 3 Marchantiophyta that were publicly available in GenBank. Our phylogenetic analysis revealed that N. nitidula was clustered in a clade with other Hypnalean taxa.

Analysis for DC and RF Characteristics Recessed-Gate GaN MOSFET Using Stacked TiO2/Si3N4 Dual-Layer Insulator.

The self-heating effects (SHEs) on the electrical characteristics of the GaN MOSFETs with a stacked TiO2/Si3N4 dual-layer insulator are investigated by using rigorous TCAD simulations. To accurately analyze them, the GaN MOSFETs with Si3N4 single-layer insulator are conducted to the simulation works together. The stacked TiO2/Si3N4 GaN MOSFET has a maximum on-state current of 743.8 mA/mm, which is the improved value due to the larger oxide capacitance of TiO2/Si3N4 than that of a Si3N4 single-layer insulator. However, the electrical field and current density increased by the stacked TiO2/Si3N4 layers make the device's temperature higher. That results in the degradation of the device's performance. We simulated and analyzed the operation mechanisms of the GaN MOSFETs modulated by the SHEs in view of high-power and high-frequency characteristics. The maximum temperature inside the device was increased to 409.89 K by the SHEs. In this case, the stacked TiO2/Si3N4-based GaN MOSFETs had 25%-lower values for both the maximum on-state current and the maximum transconductance compared with the device where SHEs did not occur; Ron increased from 1.41 mΩ·cm2 to 2.56 mΩ·cm2, and the cut-off frequency was reduced by 26% from 5.45 GHz. Although the performance of the stacked TiO2/Si3N4-based GaN MOSFET is degraded by SHEs, it shows superior electrical performance than GaN MOSFETs with Si3N4 single-layer insulator.

First-year sea ice leads to an increase in dimethyl sulfide-induced particle formation in the Antarctic Peninsula.

Dimethyl sulfide (DMS) produced by marine algae represents the largest natural emission of sulfur to the atmosphere. The oxidation of DMS is a key process affecting new particle formation that contributes to the radiative forcing of the Earth. In this study, atmospheric DMS and its major oxidation products (methanesulfonic acid, MSA; non-sea-salt sulfate, nss-SO42-) and particle size distributions were measured at King Sejong station located in the Antarctic Peninsula during the austral spring-summer period in 2018-2020. The observatory was surrounded by open ocean and first-year and multi-year sea ice. Importantly, oceanic emissions and atmospheric oxidation of DMS showed distinct differences depending on source regions. A high mixing ratio of atmospheric DMS was observed when air masses were influenced by the open ocean and first-year sea ice due to the abundance of DMS producers such as pelagic phaeocystis and ice algae. However, the concentrations of MSA and nss-SO42- were distinctively increased for air masses originating from first-year sea ice as compared to those originating from the open ocean and multi-year sea ice, suggesting additional influences from the source regions of atmospheric oxidants. Heterogeneous chemical processes that actively occur over first-year sea ice tend to accelerate the release of bromine monoxide (BrO), which is the most efficient DMS oxidant in Antarctica. Model-estimates for surface BrO confirmed that high BrO mixing ratios were closely associated with first-year sea ice, thus enhancing DMS oxidation. Consequently, the concentration of newly formed particles originated from first-year sea ice, which was a strong source area for both DMS and BrO was greater than from open ocean (high DMS but low BrO). These results indicate that first-year sea ice plays an important yet overlooked role in DMS-induced new particle formation in polar environments, where warming-induced sea ice changes are pronounced.

When river water meets seawater: Insights into primary marine aerosol production.

The impact of inorganic salts and organic matter (OM) on the production of primary marine aerosols is still under debate. To constrain their impact, we investigated primary aerosols generated by a sea-spray generator chamber using surface water samples from rivers, estuaries, and seas that were collected along salinity gradients in two temperate Korean coastal systems and one Arctic coastal system. Salinity values showed an increasing trend along the river-estuary-coastal water transition, indicating the lowest amount of inorganic salts in the river but the highest amount in the sea. In river samples, the lowest number concentration of primary aerosol particles (1.01 × 103 cm-3) was observed at the highest OM content, suggesting that low salinity controls aerosol production. Moreover, the number concentration of primary aerosols increased drastically in estuarine (1.13 × 104 cm-3) and seawater (1.35 × 104 cm-3) samples as the OM content decreased. Our results indicate that inorganic salts associated with increasing salinity play a much larger role than OM in aerosol production in river-dominated coastal systems. Laboratory studies using NaCl solution supported the conclusion that inorganic salt is a critical factor in modulating the particles produced from river water and seawater. Accordingly, this study highlights that inorganic salts are a critical factor in modulating the production of primary marine aerosols.

Fabrication of High-Density Out-of-Plane Microneedle Arrays with Various Heights and Diverse Cross-Sectional Shapes.

Out-of-plane microneedle structures are widely used in various applications such as transcutaneous drug delivery and neural signal recording for brain machine interface. This work presents a novel but simple method to fabricate high-density silicon (Si) microneedle arrays with various heights and diverse cross-sectional shapes depending on photomask pattern designs. The proposed fabrication method is composed of a single photolithography and two subsequent deep reactive ion etching (DRIE) steps. First, a photoresist layer was patterned on a Si substrate to define areas to be etched, which will eventually determine the final location and shape of each individual microneedle. Then, the 1st DRIE step created deep trenches with a highly anisotropic etching of the Si substrate. Subsequently, the photoresist was removed for more isotropic etching; the 2nd DRIE isolated and sharpened microneedles from the predefined trench structures. Depending on diverse photomask designs, the 2nd DRIE formed arrays of microneedles that have various height distributions, as well as diverse cross-sectional shapes across the substrate. With these simple steps, high-aspect ratio microneedles were created in the high density of up to 625 microneedles mm-2 on a Si wafer. Insertion tests showed a small force as low as ~ 172 µN/microneedle is required for microneedle arrays to penetrate the dura mater of a mouse brain. To demonstrate a feasibility of drug delivery application, we also implemented silk microneedle arrays using molding processes. The fabrication method of the present study is expected to be broadly applicable to create microneedle structures for drug delivery, neuroprosthetic devices, and so on.

Effects of Proton Irradiation on the Current Characteristics of SiN-Passivated AlGaN/GaN MIS-HEMTs Using a TMAH-Based Surface Pre-Treatment.

This study investigated the combined effects of proton irradiation and surface pre-treatment on the current characteristics of Gallium Nitride (GaN)-based metal-insulator-semiconductor high-electron-mobility-transistors (MIS-HEMTs) to evaluate the radiation hardness involved with the Silicon Nitride (SiN) passivation/GaN cap interface. The impact of proton irradiation on the static and dynamic current characteristics of devices with and without pre-treatment were analyzed with 5 MeV proton irradiation. In terms of transfer characteristics before and after the proton irradiation, the drain current of the devices without and with pre-treatment were reduced by an increase in sheet and contact resistances after the proton irradiation. In contrast with the static current characteristics, the gate-lag characteristics of the device with pre-treatment were significantly degenerated. In the device with pre-treatment, the hydrogen passivation for surface states of the GaN cap was formed by the pre-treatment and SiN deposition processes. Since the hydrogen passivation was removed by the proton irradiation, the newly created vacancies resulted in the degeneration of gate-lag characteristics. After nine months in an ambient atmosphere, the gate-lag characteristics of the device with pre-treatment were recovered because of the hydrogen recombination. These results demonstrated that the radiation hardness of MIS-HEMTs was affected by the SiN/GaN interface quality.

Characterization of complete mitochondrial genome in Myuroclada maximowiczii (G.G. Borshch.) Steere & W.B. Schofield.

The mitogenome of Myuroclada maximowiczii (GenBank accession number MT834960) has a total length of 104,216 bp and encodes 40 protein-coding genes, three ribosomal RNAs, and 24 transfer RNAs. The overall nucleotide composition is asymmetric (29.6% A, 29.4% T, 21.2% G, and 19.8% C), with AT content (59.0%) higher than GC content (41.0%). The gene arrangement of this mitogenome is identical to that in other bryophytes. Phylogenetic trees were constructed using complete mitochondrial genome sequences of 24 bryophytes publicly available in GenBank and the mitogenome sequence derived in this study. Our phylogenetic analysis revealed that M. maximowiczii clustered in a clade with other hypnalean taxas.

Characterization of the complete mitochondrial genome of the moss, Myurella julacea (Schwägr.) Schimp. (Bryidae, Theliaceae).

The present study reports the complete mitochondrial genome of Myurella julacea (Schwägr.) Schimp. (GenBank accession number MT850126); the genome size was 104,979 bp. The gene arrangement was found to be similar to that in other bryophytes, and the genome consisted of 40 protein-coding genes (PCGs), 3 ribosomal RNAs (rRNAs), and 24 transfer RNAs (tRNAs). The phylogenic relationship was analyzed by construction of a phylogenetic tree based on the mitogenome of M. julacea and 25 other bryophytes publicly available in GenBank. The complete mitogenome of M. julacea is expected to provide insights into the evolution of species belonging to the order Hypnales.

The complete mitochondrial genome of Eurasian Sparrowhawk Accipiter nisus (Accipitriformes: Accipitridae).

The mitogenome of the Accipiter nisus is a circular module of 18,352 bp, which consists of 39 genes, containing 2 rRNA genes (12S rRNA and 16S rRNA), 13 protein-coding genes, 22 tRNA genes, and two non-coding regions (control region and pseudo control region). The mitogenome of A. nisus is composed of 31.3% A, 25.5% T, 30.4% C, 12.8% G, and 76.3% AT. The phylogenetic analysis revealed that A. nisus individuals was well grouped in Accipitridae and more closely related to genus Circus than other Accpiter species.

The complete mitochondrial genome of a moss Korea Climacium dendroides (Hedw.) F. Weber & D. Mohr.

The complete mitochondrial genome of Climacium dendroides (GenBank accession number MN942036 was 104,860 base pairs in length, containing 40 protein-coding genes, 3 ribosomal RNA (rRNA), and 24 transfer RNA (tRNA). The base composition was 29.6% A, 29.4% T, 21.0% G, and 19.8% C and its G + C content was 41.0%. The mitochondrial structure and gene order was similar to other Bryophytes. Phylogenetic tree based on the combined analysis of 33 protein-coding genes was well congruent with traditional species relationship of the moss order Hypnales.

The complete chloroplast genome of a moss Korea Climacium dendroides (Hedw.) F. Weber & D. Mohr.

The complete chloroplast (cp) genome sequence of Climacium dendroides, determined using Illumina sequencing data, is presented herein. The DNA sequence of C. dendroides is 124,957 bp in length and has an overall CG content of 29.0%, including 82 protein-coding genes, 36 transfer RNA genes, and 8 ribosomal RNA genes. Phylogenetic trees were constructed based on the cp genome sequences of 10 bryophytes downloaded from GenBank and one acquired from this study.