Synthesis of Graphitic Carbon Coated ZnPS3 and its Superior Electrochemical Properties for Lithium and Sodium Ion Storage.

Graphitic carbon-coated ZnPS3 is prepared via direct phosphosulfurization and high energy mechanical milling (HEMM) with multiwall carbon nanotubes (MWCNTs) and first introduced as an anode for lithium-ion batteries (LIBs) and sodium-ion batteries (SIBs). The HEMM process with MWCNTs reduces the particle size of as-synthesized ZnPS3 bulk to 100-500 nm and yields the ≈5 nm thick graphitic carbon coated ZnPS3 nanoparticles, which are the nanocomposites of 5 nm sized nanocrystallites embedded in the amorphous matrix. The ZnPS3 electrode undergoes the combined conversion and alloying reactions with Li and Na ions and exhibits high initial discharge and charge capacities in both LIBs and SIBs. The graphitic carbon-coated ZnPS3 electrode exhibits excellent high-rate capability and long-term cyclability. The superior electrochemical properties can be attributed to high electrical conductivity, high Li ion mobility, and high reversibility and structural stability derived from the graphitic carbon-coated nanoparticles. This study demonstrates that the novel graphitic carbon-coated ZnPS3 is a promising anode material for both LIBs and SIBs and the graphitic carbon coating methodology by HEMM is expected to apply to the various metal oxides, sulfides, and phosphides.

Possible species discrimination of a blotched nerite Nerita albicilla with their distribution pattern and demographic history in the Indo-Pacific.

The blotched nerite Nerita albicilla (Linnaeus 1758) is distributed in intertidal areas of the Indo-Pacific. In South Korea, it has been found only in the southernmost region of Jeju Island so far. Owing to its limited distribution, it can be a promising intertidal species helpful for monitoring global climate change effects in the Korean Peninsula. We performed population genetic analyses based on 393 COI haplotypes from 697 N. albicilla, including 167 from this study and 530 from public databases. The results showed that there are two distinct genetic lineages in N. albicilla: PAIO (Palearctic, Australasia, Indo-Malay, and Oceania) and Afrotropic lineages. DNA barcoding gap analyses indicated that the two lineages could be differentiated into two different species: N. albicilla (PAIO) and N. originalis sp. nov. (Afrotropic) (3.96%). Additionally, it was revealed that their divergence time was ca. 5.96 Ma and dramatic diversification of COI haplotypes occurred during the late Pliocene and Pleistocene. The results of MDA, BSP, and neutrality test implied recent population size expansion, which was estimated to be ca. 250 Ka. Finally, we discussed whether the observation of N. originalis sp. nov. in South Korea is due to the northward migration through ocean currents caused by global warming or due to artificial activity through marine transportation.

Mapping the electrocatalytic water splitting activity of VO2 across its insulator-to-metal phase transition.

The electrocatalytic water splitting activity of V-based oxides has been rarely investigated, even though several polymorphs in VO2 are expected to exhibit different electrocatalytic activities depending on their crystal and electronic structures. The rutile structure of VO2(R), showing metallic character, is a good candidate for a new electrocatalyst since it undergoes insulator-to-metal transition (IMT) from the insulating VO2(M1) at a low temperature of 68 °C, and involves a substantially increased electrical conductivity by three orders of magnitude. The extensive improvements in the electrocatalytic activity for both the oxygen evolution reaction (OER) and the hydrogen evolution reaction (HER) are confirmed when the IMT is induced where the overpotential (η10) is reduced from 1056 mV to 598 mV in the OER and 411 mV to 136 mV in the HER, respectively. This improvement is attributed to the increased electrochemically active surface area (ECSA), reduced charge transfer resistance, and increased electron density, driven by the IMT to the metallic VO2(R) phase.

Loss of the transcription repressor ZHX3 induces senescence-associated gene expression and mitochondrial-nucleolar activation.

Cellular senescence is accompanied by metabolic and epigenomic remodeling, but the transcriptional mechanism of this process is unclear. Our previous RNA interference-based screen of chromatin factors found that lysine methyltransferases including SETD8 and NSD2 inhibited the senescence program in cultured fibroblasts. Here, we report that loss of the zinc finger and homeobox protein 3 (ZHX3), a ubiquitously expressed transcription repressor, induced senescence-associated gene expression and mitochondrial-nucleolar activation. Chromatin immunoprecipitation-sequencing analyses of growing cells revealed that ZHX3 was enriched at the transcription start sites of senescence-associated genes such as the cyclin-dependent kinase inhibitor (ARF-p16INK4a) gene and ribosomal RNA (rRNA) coding genes. ZHX3 expression was consistently downregulated in cells with replicative or oncogene-induced senescence. Mass spectrometry-based proteomics identified 28 proteins that interacted with ZHX3, including ATP citrate lyase and RNA metabolism proteins. Loss of ZHX3 or ZHX3-interaction partners by knockdown similarly induced the expression of p16INK4a and rRNA genes. Zhx3-knockout mice showed upregulation of p16INK4a in the testes, thymus and skeletal muscle tissues, together with relatively short survival periods in males. These data suggested that ZHX3 plays an essential role in transcriptional control to prevent cellular senescence.

Visible Light Driven Ultrasensitive and Selective NO2 Detection in Tin Oxide Nanoparticles with Sulfur Doping Assisted by l-Cysteine.

In the pandemic era, the development of high-performance indoor air quality monitoring sensors has become more critical than ever. NO2 is one of the most toxic gases in daily life, which induces severe respiratory diseases. Thus, the real-time monitoring of low concentrations of NO2 is highly required. Herein, a visible light-driven ultrasensitive and selective chemoresistive NO2 sensor is presented based on sulfur-doped SnO2 nanoparticles. Sulfur-doped SnO2 nanoparticles are synthesized by incorporating l-cysteine as a sulfur doping agent, which also increases the surface area. The cationic and anionic doping of sulfur induces the formation of intermediate states in the band gap, highly contributing to the substantial enhancement of gas sensing performance under visible light illumination. Extraordinary gas sensing performances such as the gas response of 418 to 5 ppm of NO2 and a detection limit of 0.9 ppt are achieved under blue light illumination. Even under red light illumination, sulfur-doped SnO2 nanoparticles exhibit stable gas sensing. The endurance to humidity and long-term stability of the sensor are outstanding, which amplify the capability as an indoor air quality monitoring sensor. Overall, this study suggests an innovative strategy for developing the next generation of electronic noses.

Transcriptome Analysis of Testicular Aging in Mice.

Male reproductive aging, or andropause, is associated with gradual age-related changes in testicular properties, sperm production, and erectile function. The testis, which is the primary male reproductive organ, produces sperm and androgens. To understand the transcriptional changes underlying male reproductive aging, we performed transcriptome analysis of aging testes in mice. A total of 31,386 mRNAs and 9387 long non-coding RNAs (lncRNAs) were identified in the mouse testes of diverse age groups (3, 6, 12, and 18 months old) by total RNA sequencing. Of them, 1571 mRNAs and 715 lncRNAs exhibited changes in their levels during testicular aging. Most of these aging-related transcripts exhibited slight and continuous expression changes during aging, whereas some (9.6%) showed larger expression changes. The aging-related transcripts could be classified into diverse expression patterns, in which the transcripts changed mainly at 3-6 months or at 12-18 months. Our subsequent in silico analysis provided insight into the potential features of testicular aging-related mRNAs and lncRNAs. We identified testis-specific aging-related transcripts (121 mRNAs and 25 lncRNAs) by comparison with a known testis-specific transcript profile, and then predicted the potential reproduction-related functions of the mRNAs. By selecting transcripts that are altered only between 3 and 18 months, we identified 46 mRNAs and 34 lncRNAs that are stringently related to the terminal stage of male reproductive aging. Some of these mRNAs were related to hormonal regulation. Finally, our in silico analysis of the 34 aging-related lncRNAs revealed that they co-localized with 19 testis-expressed protein-coding genes, 13 of which are considered to show testis-specific or -predominant expression. These nearby genes could be potential targets of cis-regulation by the aging-related lncRNAs. Collectively, our results identify a number of testicular aging-related mRNAs and lncRNAs in mice and provide a basis for the future investigation of these transcripts in the context of aging-associated testicular dysfunction.

A MnV2O6/graphene nanocomposite as an efficient electrocatalyst for the oxygen evolution reaction.

A MnV2O6/graphene nanocomposite was fabricated through hydrothermal synthesis and high energy milling to introduce it as an efficient OER electrocatalyst. The MnV2O6/graphene nanocomposite with 20 wt% graphene exhibited superior electrocatalytic OER performance with a low overpotential and high stability and durability in 1 M KOH aqueous solution, exhibiting even after 1000 CV cycles.

Electrical Transport and Thermoelectric Properties of SnSe-SnTe Solid Solution.

SnSe is considered as a promising thermoelectric (TE) material since the discovery of the record figure of merit (ZT) of 2.6 at 926 K in single crystal SnSe. It is, however, difficult to use single crystal SnSe for practical applications due to the poor mechanical properties and the difficulty and cost of fabricating a single crystal. It is highly desirable to improve the properties of polycrystalline SnSe whose TE properties are still not near to that of single crystal SnSe. In this study, in order to control the TE properties of polycrystalline SnSe, polycrystalline SnSe-SnTe solid solutions were fabricated, and the effect of the solid solution on the electrical transport and TE properties was investigated. The SnSe1-xTex samples were fabricated using mechanical alloying and spark plasma sintering. X-ray diffraction (XRD) analyses revealed that the solubility limit of Te in SnSe1-xTex is somewhere between x = 0.3 and 0.5. With increasing Te content, the electrical conductivity was increased due to the increase of carrier concentration, while the lattice thermal conductivity was suppressed by the increased amount of phonon scattering. The change of carrier concentration and electrical conductivity is explained using the measured band gap energy and the calculated band structure. The change of thermal conductivity is explained using the change of lattice thermal conductivity from the increased amount of phonon scattering at the point defect sites. A ZT of ~0.78 was obtained at 823 K from SnSe0.7Te0.3, which is an ~11% improvement compared to that of SnSe.

A P2-type Na0.7(Ni0.6Co0.2Mn0.2)O2 cathode with excellent cyclability and rate capability for sodium ion batteries.

A new P2-type Na0.7(Ni0.6Co0.2Mn0.2)O2 was prepared via co-precipitation and its electrochemical properties as a cathode for sodium ion batteries were compared with those of O3-type Na(Ni0.6Co0.2Mn0.2)O2, focusing on phase stability and cycling performance. The P2-type delivered a high capacity of 108 mA h g-1 after 300 cycles at 2C.

Stable Silicon Anode for Lithium-Ion Batteries through Covalent Bond Formation with a Binder via Esterification.

Silicon (Si) is considered to be one of the most promising anode candidates for next-generation lithium-ion batteries because of its high theoretical specific capacity and low discharge potential. However, its poor cyclability, caused by tremendous volume change during cycling, prevents commercial use of the Si anode. Herein, we demonstrate a high-performance Si anode produced via covalent bond formation between a commercially available Si nanopowder and a linear polymeric binder through an esterification reaction. For efficient ester bonding, polyacrylic acid, composed of -COOH groups, is selected as the binder, Si is treated with piranha solution to produce abundant -OH groups on its surface, and sodium hypophosphite is employed as a catalyst. The as-fabricated electrode exhibits excellent high rate capability and long cycle stability, delivering a high capacity of 1500 mA h g-1 after 500 cycles at a high current density of 1000 mA g-1 by effectively restraining the susceptible sliding of the binder, stabilizing the solid electrolyte interface layer, preventing the electrode delamination, and suppressing the Si aggregation. Furthermore, a full cell is fabricated with as-fabricated Si as an anode and commercially available LiNi0.6Mn0.2Co0.2O2 as a cathode, and its electrochemical properties are investigated for the possibility of practical use.

Solid solution phosphide (Mn1-xFexP) as a tunable conversion/alloying hybrid anode for lithium-ion batteries.

The substitutional solid solution Mn1-xFexP compounds between alloying reaction-type MnP and conversion reaction-type FeP are successfully synthesized via facile high energy mechanical milling and their electrochemical properties as an anode for lithium ion batteries (LIBs) are investigated. A complete solid solution is formed between two end members and the Mn1-xFexP solid solution phosphide electrodes show an enhanced electrochemical performance, delivering a capacity of 360 mA h g-1 after 100 cycles at a high current density of 2 A g-1 when the advantages of the two reaction mechanisms are beneficially combined. These synergistic effects resulted from the in situ generated nanocomposite of the Li-Mn-P alloying element and the Fe nano-network in combination with the surrounding amorphous lithium phosphide, which effectively buffers the accompanying volume variation, hinders the aggregation of the alloying element, and ensures the electron and ion transport.

Mesoporous Si-Cu nanocomposite anode for a lithium ion battery produced by magnesiothermic reduction and electroless deposition.

Copper deposited mesoporous silicon was fabricated by magnesiothermic reduction and electroless deposition and its electrochemical properties as an anode for lithium ion batteries were investigated. The 300-400 nm sized mesoporous Si particles were synthesized by magnesiothermic reduction of SiO2 nanospheres prepared by the Stöber method. The mesopores of Si particles were effectively decorated with Cu using Sn sensitization/Pd activation and subsequent Cu electroless deposition. The homogeneous distribution of Cu inside the mesoporous Si particles was confirmed by high resolution transmission electron microscopy images and energy dispersive spectroscopy mapping on the cross-sectional specimen prepared by a focused ion beam. The mesoporous Si-Cu nanocomposite exhibited high initial Coulombic efficiency, long cycle stability, and high rate capability, delivering a high capacity of 1569 mAh g-1 after 200 cycles at the current density of 1000 mA g-1. The improved electrochemical performance in a mesoporous Si-Cu nanocomposite was attributed to the high electrical conductivity, high Li+ ion mobility, and structural stability to restrict the aggregation and pulverization of active materials.

Revisiting Primary Particles in Layered Lithium Transition-Metal Oxides and Their Impact on Structural Degradation.

Layered lithium transition-metal oxide materials, e.g., Li(Ni1- x - y Co x Mn y )O2 (NCM) and Li(Ni1- x - y Co x Al y )O2, are the most promising candidates for lithium-ion battery cathodes. They generally consist of ≈10 µm spherical particles densely packed with smaller particles (0.1-1 µm), called secondary and primary particles, respectively. The micrometer- to nanometer-sized particles are critical to the battery performance because they affect the reaction capability of the cathode. Herein, the crystal structure of the primary particles of NCM materials is revisited. Elaborate transmission electron microscopy investigations reveal that the so-called primary particles, often considered as single crystals, are in fact polycrystalline secondary particles. They contain low-angle and exceptionally stable special grain boundaries (GBs) presumably created during aggregation via an oriented attachment mechanism. Therefore, this so-called primary particle is renamed as primary-like particle. More importantly, the low-angle GBs between the smaller true primary particles cause the development of nanocracks within the primary-like particles of Ni-rich NCM cathodes after repetitive electrochemical cycles. In addition to rectifying a prevalent misconception about primary particles, this study provides a previously unknown but important origin of structural degradation in Ni-rich layered cathodes.

The Role of Zr Doping in Stabilizing Li[Ni0.6 Co0.2 Mn0.2 ]O2 as a Cathode Material for Lithium-Ion Batteries.

Ni-rich layered LiNi1-x-y Cox Mny O2 systems are the most promising cathode materials for high energy density Li-ion batteries (LIBs). However, Ni-rich cathode materials inevitably suffer from rapid capacity fading and poor rate capability owing to structural instability and unstable surface side reactions. Zr doping has proven to be an effective method to enhance the cycle and rate performances by stabilizing the structure and increasing the Li+ diffusion rate. Herein, effects of Zr-doping on the structural stability and Li+ diffusion kinetics are thoroughly investigated in LiNi0.6 Co0.2 Mn0.2 O2 (LNCM) cathode material using atomic-resolution scanning transmission electron microscopy imaging, XRD Rietveld refinement, and density functional theory calculations. Zr doping mitigates the degree of cation mixing, decreases the structural transformation, and facilitates Li+ diffusion resulting in improved cyclic performance and rate capability. Based on the obtained results, an atomistic model is proposed to explain the effects of Zr doping on the structural stability and Li+ diffusion kinetics in LNCM cathode materials.

Superior electrochemical sodium storage of V4P7 nanoparticles as an anode for rechargeable sodium-ion batteries.

V4P7 nanoparticles were synthesized via high-energy mechanical milling and their electrochemical properties as an anode for sodium-ion batteries were studied and compared with those of VO2(B)/Na and V4P7/Li cells, focusing on the electrochemical reaction mechanism and cycle performance. The V4P7 showed excellent cycling behavior even without any conductive material.

Synthetic Mechanism Discovery of Monophase Cuprous Oxide for Record High Photoelectrochemical Conversion of CO2 to Methanol in Water.

Precise control of the oxidation state of transition-metal oxides, such as copper, is important for high selectivity of CO2 reduction in an aqueous condition to compete with the reduction of water. The phase of copper oxide nanofibers was controlled by predictive synthesis, which controls the nanoscale gas-solid reaction by considering thermodynamics and kinetics. The driving force of the phase transformation between the different oxidation states of copper oxide is calculated by comparing the Gibbs free energy of each of the oxidation states. From the calculation, the kinetically processable window for the fabrication of Cu2O in which monophase Cu2O can be fabricated in a reasonable reaction time scale is discovered. Herein, we report the monophase Cu2O nanofiber photocathode, which photoelectrochemically converted CO2 into methanol with over 90% selectivity in an aqueous electrolyte, and a hierarchical structure is developed to optimize the photoactivity and stability of the electrode. Our work suggests a rational design of the calcination strategy for precisely controlling the oxidation states of transition metals that can be applied to various applications in which the phase of the materials plays an important role.

CuBi2O4 Prepared by the Polymerized Complex Method for Gas-Sensing Applications.

Multicomponent oxides can be extensively explored as alternative gas-sensing materials to binary oxides with their structural and compositional versatilities. In this work, the gas-sensing properties of CuBi2O4 have been investigated toward various reducing gases (C2H5OH, NH3, H2, CO, and H2S) and oxidizing gas (NO2) for the first time. For this, the powder synthesis has been developed using the polymerized complex method (Pechini method) to obtain a single-phase polycrystalline CuBi2O4. The defect, optical, and electronic properties in the prepared CuBi2O4 powder were modulated by varying the calcination temperature from 500 to 700 °C. Noticeably, a high concentration of Cu+-oxygen vacancy ([Formula: see text]) defect complexes and isolated Cu2+ ion clusters was found in the 500 °C-calcined CuBi2O4, where they were removed through air calcination at higher temperatures (up to 700 °C) while making the compound more stoichiometric. The change in the intrinsic defect concentration with the calcination temperature led to the variation of the electronic band gap energy and hole concentration in CuBi2O4 with the polaronic hopping conduction (activation energy = 0.43 eV). The CuBi2O4 sensor with 500 °C-calcined powder showed the highest gas responses (specifically, 10.4 toward 1000 ppm C2H5OH at the operating temperature of 400 °C) with the highest defect concentration. As a result, the gas-sensing characteristics of CuBi2O4 are found to be dominantly affected by the intrinsic defect concentration, which is controlled by the calcination temperature. Toward reducing H2S and oxidizing NO2 gases, the multiple reactions arising simultaneously on the surface of the CuBi2O4 sensor govern its response behavior, depending on the gas concentration and the operating temperature. We believe that this work can be a cornerstone for understanding the effect of chemical defect on the gas-sensing characteristics in multicomponent oxides.

Novel Calcium Zirconate Silicate Cement Biomineralize and Seal Root Canals.

This study evaluated the sealing ability of gutta-percha (GP) with a calcium silicate-based sealer and a novel calcium zirconate containing calcium silicate cement (ZC). The root canals of the extracted premolars were prepared, which were then randomly allocated to three experimental groups (12 root canals per group) for obturation by continuous wave of condensation with the GP and AH 26 sealer (CW); obturation using a single GP with a calcium silicate-based EndoSequence BC sealer (SC); or obturation with ZC. The roots were inserted into sterile Eppendorf tubes, which were inoculated coronally with Porphyromonas gingivalis. The amount of endotoxin leakage into the apical reservoirs were measured using the Limulus Amebocyte Lysate (LAL) assay over 21 days, with comparisons made using one-way ANOVA and Scheffe's tests (α = 0.05). After 21 days, 75% of the canals that had been obturated by SC, 50% of those obturated by CW and 42% of those obturated by ZC showed endotoxin leakage. The amount of leakage was higher in the SC canals than in the CW (p = 0.031) or ZC (p = 0.03) canals, although there was no significant difference in the amount of leakage for CW and ZC (p > 0.05). X-ray diffraction revealed the presence of tricalcium silicate (Ca3SiO5) and calcium zirconate (CaZrO3) in the synthesized ZC. Scanning electron microscopy revealed mineralized precipitates on the dentin of canals obturated by ZC. The novel calcium zirconate silicate cement appears to promote biomineralization and seal root canals at least as effectively as the conventional sealer.

Highly stable SnO2-Fe2O3-C hollow spheres for reversible lithium storage with extremely long cycle life.

SnO2-Fe2O3-C triple-shell hollow nano-spheres are fabricated by combining the template-based sol-gel coating technique and hydrothermal method, and their electrochemical performance as an anode for lithium ion batteries (LIBs) is investigated, particularly focusing on their structural stability and long term cyclability. To accomplish this, same-sized SnO2 solid spheres, Fe2O3 solid spheres, SnO2-Fe2O3 solid spheres, SnO2-Fe2O3-C solid spheres, SnO2 hollow spheres and SnO2-Fe2O3 hollow spheres are prepared in a similar manner and their cyclic performances are compared. It is found that the as-synthesized 80 nm-sized SnO2-Fe2O3-C hollow sphere electrode exhibits an extraordinary reversible capacity (1100 mA h g-1 after 100 cycles at 200 mA g-1) and excellent long cycle stability (475 mA h g-1 after 1000 cycles at 2000 mA g-1), which are attributed to the Fe-enhanced reversibility of the Li2O reduction reaction, high electrical conductivity, high Li+ ion mobility, and structural stability of the carbon-coated triple-shell hollow spheres.

Superior sodium storage performance of reduced graphene oxide-supported Na3.12Fe2.44(P2O7)2/C nanocomposites.

In this study, a reduced graphene oxide-supported Na3.12Fe2.44(P2O7)2/C nanocomposite was successfully synthesized by a sol-gel method and a subsequent heat-treatment process. Not only did the composite undergo a highly reversible electrochemical reaction, but it also exhibits superior rate capability and long-term cyclic stability as a Na-ion battery cathode.