Group-Connected Impedance Network of RIS-Assisted Rate-Splitting Multiple Access in MU-MIMO Wireless Communication Systems.

The reconfigurable intelligent surface (RIS) and rate-splitting multiple access (RSMA) are considered as promising technologies for the beyond Fifth-Generation (B5G) and Sixth-Generation (6G) wireless systems by controlling the propagation environment, which attenuates the transmitted signal, and by managing the interference by splitting the user message into common and private messages. Because conventional RIS elements have each impedance connected to the ground, the sum-rate performance improvement of the RIS is limited. Therefore, the new RISs, which have impedance elements connected to each other, have been proposed recently. To be more adaptive to each channel, the optimization of the grouping of the RIS elements is required. Furthermore, since the solution of the optimal rate-splitting (RS) power-splitting ratio is complex, the value should be simply optimized to be more practical in the wireless system. In this paper, the grouping scheme of the RIS elements according to the user scheduling and the solution of the RS power-splitting ratio based on fractional programming (FP) are proposed. The simulation results showed that the proposed RIS-assisted RSMA system achieved a high sum-rate performance compared to the conventional RIS-assisted spatial-division multiple access (SDMA) system. Therefore, the proposed scheme can perform adaptively for the channel and has a flexible interference management. Furthermore, it can be a more suitable technique for B5G and 6G.

Nonvolatile High-Speed Switching Zn-O-N Thin-Film Transistors with a Bilayer Structure.

Zinc oxynitride (ZnON) has the potential to overcome the performance and stability limitations of current amorphous oxide semiconductors because ZnON-based thin-film transistors (TFTs) have a high field-effect mobility of 50 cm2/Vs and exceptional stability under bias and light illumination. However, due to the weak zinc-nitrogen interaction, ZnON is chemically unstable─N is rapidly volatilized in air. As a result, recent research on ZnON TFTs has focused on improving air stability. We demonstrate through experimental and first-principles studies that the ZnF2/ZnON bilayer structure provides a facile way to achieve air stability with carrier controllability. This increase in air stability (e.g., nitrogen non-volatilization) occurs because the ZnF2 layer effectively protects the atomic mixing between ZnON and air, and the decrease in the ZnON carrier concentration is caused by a shallow-to-deep electronic transition of nitrogen deficiency diffused from ZnON into the interface. Further, the TFT based on the ZnF2/ZnON bilayer structure enables long-term air stability while retaining an optimal switching property of high field-effect mobility (∼100 cm2/Vs) even at a relatively low post-annealing temperature. The ZnF2/ZnON-bilayer TFT device exhibits fast switching behavior between 1 kHz and 0.1 MHz while maintaining a stable and clear switching response, paving the way for next-generation high-speed electronic applications.

Chemically Tunable Organic Dielectric Layer on an Oxide TFT: Poly(p-xylylene) Derivatives.

Inorganic materials such as SiOx and SiNx are commonly used as dielectric layers in thin-film transistors (TFTs), but recent advancements in TFT devices, such as inclusion in flexible electronics, require the development of novel types of dielectric layers. In this study, CVD-deposited poly(p-xylylene) (PPx)-based polymers were evaluated as alternative dielectric layers. CVD-deposited PPx can produce thin, conformal, and pinhole-free polymer layers on various surfaces, including oxides and metals, without interfacial defects. Three types of commercial polymers were successfully deposited on various substrates and exhibited stable dielectric properties under frequency and voltage sweeps. Additionally, TFTs with PPx as a dielectric material and an oxide semiconductor exhibited excellent device performance; a mobility as high as 22.72 cm2/(V s), which is the highest value among organic gate dielectric TFTs, to the best of our knowledge. Because of the low-temperature deposition process and its unprecedented mechanical flexibility, TFTs with CVD-deposited PPx were successfully fabricated on a flexible plastic substrate, exhibiting excellent durability over 10000 bending cycles. Finally, a custom-synthesized functionalized PPx was introduced into top-gated TFTs, demonstrating the possibility for expanding this concept to a wide range of chemistries with tunable gate dielectric layers.

Natural Sulfurs Inhibit LPS-Induced Inflammatory Responses through NF-κB Signaling in CCD-986Sk Skin Fibroblasts.

Lipopolysaccharide (LPS)-induced inflammatory response leads to serious damage, up to and including tumorigenesis. Natural mineral sulfur, non-toxic sulfur (NTS), and methylsulfonylmethane (MSM) have anti-inflammatory activity that may inhibit LPS-induced inflammation. We hypothesized that sulfur compounds could inhibit LPS-induced inflammatory responses in CCD-986Sk skin fibroblasts. We used Western blotting and real-time PCR to analyze molecular signaling in treated and untreated cultures. We also used flow cytometry for cell surface receptor analysis, comet assays to evaluate DNA damage, and ELISA-based cytokine detection. LPS induced TLR4 activation and NF-κB signaling via canonical and protein kinase C (PKC)-dependent pathways, while NTS and MSM downregulated that response. NTS and MSM also inhibited LPS-induced nuclear accumulation and binding of NF-κB to proinflammatory cytokines COX-2, IL-1ß, and IL-6. Finally, the sulfur compounds suppressed LPS-induced ROS accumulation and DNA damage in CCD-986Sk cells. These results suggest that natural sulfur compounds could be used to treat inflammation and may be useful in the development of cosmetics.

Non-toxic sulfur inhibits LPS-induced inflammation by regulating TLR-4 and JAK2/STAT3 through IL-6 signaling.

Janus kinase 2 (JAK2) and STAT3 signaling is considered a major pathway in lipopolysaccharide (LPS)­induced inflammation. Toll­like receptor 4 (TLR­4) is an inflammatory response receptor that activates JAK2 during inflammation. STAT3 is a transcription factor for the pro­inflammatory cytokine IL­6 in inflammation. Sulfur is an essential element in the amino acids and is required for growth and development. Non­toxic sulfur (NTS) can be used in livestock feeds as it lacks toxicity. The present study aimed to inhibit LPS­induced inflammation in C2C12 myoblasts using NTS by regulating TLR­4 and JAK2/STAT3 signaling via the modulation of IL­6. The 3­(4,5­dimethylthiazol­2­yl)­2,5­diphenyltetrazolium bromide assay was conducted to analyze cell viability and reverse transcription polymerase chain reaction and western blotting performed to measure mRNA and protein expression levels. Chromatin immunoprecipitation and enzyme­linked immunosorbent assays were used to determine the binding activity of proteins. The results indicated that NTS demonstrated a protective effect against LPS­induced cell death and inhibited LPS­induced expression of TLR­4, JAK2, STAT3 and IL­6. In addition, NTS inhibited the expression of nuclear phosphorylated­STAT3 and its binding to the IL­6 promoter. Therefore, NTS may be a potential candidate drug for the treatment of inflammation.

Significant enhancement of the bias stability of Zn-O-N thin-film transistors via Si doping.

Si doping was used to significantly improve the bias stability of ZnON thin-film transistors. Si 3 W (~1%) doped ZnON TFTs showed a saturation mobility of 19.70 cm2/Vs along with remarkable improvements in the threshold voltage shift for negative gate bias stress (NBS) within 1.69 V. The effects of Si doping were interpreted by the experimental correlation between device performance and physical analysis, as well as by the theoretical calculation. Si doping induces the reduction of N-related defects by increasing stoichiometric Zn3N2, and decreasing nonstoichiometric ZnxNy. In addition, Si doping reduces the band edge states below the conduction band. According to density functional theory (DFT) calculations, Si, when it substitutes for Zn, acts as a carrier suppressor in the ZnON matrix.

Amorphous Mixture of Two Indium-Free BaSnO3 and ZnSnO3 for Thin-Film Transistors with Balanced Performance and Stability.

The trade-off between performance and stability in amorphous oxide semiconductor-based thin-film transistors (TFTs) has been a critical challenge, meaning that it is difficult to simultaneously achieve high mobility and stability under bias and light stresses. Here, an amorphous mixture of two indium-free BaSnO3 and ZnSnO3 compounds, a-(Zn,Ba)SnO3, is proposed as a feasible strategy to achieve high mobility and stability at the same time. The choice of BaSnO3 as a counterpart to ZnSnO3, a well-known In-free candidate in amorphous oxide semiconductors, is to improve structural order and oxygen stoichiometry due to the large heat of formation and to preserve electron mobility due to the same kind of octahedral Sn-O network. Our first-principles calculations indeed show that compared to pure a-ZnSnO3, BaSnO3 plays a crucial role in restoring structural order in both stoichiometric and O-deficient supercells without seriously damaging the conduction band minimum. The resulting features of a-(Zn,Ba)SnO3 reduce O-deficiency and the valence band tail states, which are known to be critically associated with instability. It is experimentally demonstrated that a-(Zn,Ba)SnO3-based TFTs simultaneously exhibit high mobility (>20 cm2 V-1 s-1) and remarkable stability against negative bias illumination stress (ΔVth: <0.9 V). Our results suggest that a-(Zn,Ba)SnO3 would be a strong In-free candidate for next-generation TFT display, replacing the conventional a-InGaZnO4.

Non­toxic sulfur enhances growth hormone signaling through the JAK2/STAT5b/IGF­1 pathway in C2C12 cells.

Insulin­like growth factor­1 (IGF­1) regulates cell growth, glucose uptake and protein metabolism, and is required for growth hormone (GH) signaling­mediated insulin production and secretion. IGF1 expression is associated with STAT5, which binds to a region (TTCNNNGAA) of the gene. Although sulfur is used in various fields, the toxicity of this element is a significant disadvantage as it causes indigestion, vomiting, diarrhea, pain and migraine. Therefore, it is difficult to conduct in vitro experiments to directly determine the effects of dietary sulfur. Additionally, it is difficult to dissolve non­toxic sulfur (NTS). The present study aimed to identify the role of NTS in GH signaling as a Jak2/STAT5b/IGF­1 pathway regulator. MTT assay was used to identify an optimum NTS concentration for C2C12 mouse muscle cells. Western blotting, RT­PCR, chromatin immunoprecipitation, overexpression and small interfering RNA analyses were performed. NTS was dissolved in 1 mg/ml DMSO and could be used in vitro. Therefore, the present study determined whether NTS induced mouse muscle cell growth via GH signaling. NTS notably increased STAT5b binding to the Igf1 promoter. NTS also promoted GH signaling by upregulating GH receptor expression, similar to GH treatment. NTS enhanced GH signaling by regulating Jak2/STAT5b/IGF­1 signaling pathway factor expression in C2C12 mouse muscle cells. Thus, NTS may be used as a GH­enhancing growth stimulator.

Highly Stable Thin-Film Transistors Based on Indium Oxynitride Semiconductor.

In this study, the properties of indium oxynitride (InON) semiconductor films grown by reactive radio frequency sputtering were examined both experimentally and theoretically. Also, thin-film transistors (TFTs) incorporating InON as the active layer were evaluated for the first time. It is found that InON films exhibit high stability upon prolonged exposure to air and the corresponding TFTs are more stable when subjected to negative bias illumination stress, compared to devices based on indium oxide (In2O3) or zinc oxynitride (ZnON) semiconductors. X-ray photoelectron spectroscopy analyses of the oxygen 1s peaks suggest that as nitrogen is incorporated into In2O3 to form InON, the relative fraction of oxygen-deficient regions decreases significantly, which is most likely to occur by having the valence band maximum shifted up. Density functional theory calculations indicate that the formation energy of InN is much lower than Zn3N2, thus accounting for the higher stability of InON compared to ZnON in air.

Effects of Fluorine Doping on the Electrical Performance of ZnON Thin-Film Transistors.

In this work, the effects of fluorine incorporation in high mobility zinc oxynitride (ZnON) semiconductor are studied by both theoretical calculations and experimental evaluation of thin film transistors (TFTs). From density functional theory (DFT) calculations, fluorine acts as a carrier suppressor in the ZnON matrix when it substitutes a nitrogen vacant site (VN). Thin films of ZnON and ZnON:F were grown by reactively cosputtering Zn metal and ZnF2 targets, and their electrical, physical, and chemical characteristics were studied. X-ray photoelectron spectroscopy (XPS) analyses of the nitrogen 1s peaks in ZnON and ZnON:F suggest that as the fluorine incorporation increases, the relative fraction of Zn-N bonds from stoichiometric Zn3N2 increases. On the other hand, the Zn-N bond characteristics arising from nonstoichiometric ZnxNy and N-N bonds decrease, implying that indeed fluorine anions have an effect of passivating the N-related defects. The corresponding TFTs exhibit optimum transfer characteristics and switching ability when approximately 3.5 atomic percent of fluorine is present in the 40 nm thick ZnON:F active layer.