High-Performance Nickel-Bismuth Oxide Electrocatalysts Applicable to Both the HER and OER in Alkaline Water Electrolysis.

As an electrocatalyst for water electrolysis, nickel oxide (NiO) has received significant attention due to its cost-effectiveness and high reactivity among non-noble-metal-based catalytic materials. However, NiO still exhibits poor alkaline hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) kinetics compared to conventional noble metal-based catalysts. This is because NiO has a strong interaction with protons for the HER and too low free energy of the OH* state, resulting in slower rate-determining step (RDS) kinetics for the OER.

Galvanic hydrogenation reaction in metal oxide.

Rational reforming of metal oxide has a potential importance to modulate their inherent properties toward appealing characteristics for various applications. Here, we present a detailed fundamental study of the proton migration phenomena between mediums and propose the methodology for controllable metal oxide hydrogenation through galvanic reactions with metallic cation under ambient atmosphere. As a proof of concept for hydrogenation, we study the role of proton adoption on the structural properties of molybdenum trioxide, as a representative, and its impact on redox characteristics in Li-ion battery (LiB) systems using electrochemical experiments and first-principles calculation.

Quasiballistic thermal transport in submicron-scale graphene nanoribbons at room-temperature.

Phonon transport in two-dimensional materials has been the subject of intensive studies both theoretically and experimentally. Recently observed unique phenomena such as Poiseuille flow at low temperature in graphene nanoribbons (GNRs) initiated strong interest in similar effects at higher temperatures. Here, we carry out massive molecular dynamics simulations to examine thermal transport in GNRs at room temperature (RT) and demonstrate that non-diffusive behaviors including Poiseuille-like local thermal conductivity and second sound are obtained, indicating quasiballistic thermal transport.

Zero power infrared sensing in 2D/3D-assembled heterogeneous graphene/In/InSe/Au.

Low- or self-powered infrared sensors can be used in a broad range of applications, including networking mobile edge devices and image recognition for autonomous driving technology. Here, we show state-of-the-art self-powered near-infrared (NIR) sensors using graphene/In/InSe/Au as a photoactive region. The self-powered NIR sensors show outstanding performance, achieving a photoresponsivity of ∼8.

MgSi(MoO) as a High-Performance Cathode Active Material for Magnesium-Ion Batteries.

The natural abundance of magnesium together with its high volumetric energy capacity and less-dendritic anodes makes Mg-ion batteries an appealing alternative to the widely used Li-ion batteries. However, Mg cathode materials under current investigation suffer from various shortcomings such as low operation voltage and high energy barrier for ion migration, resulting in poor battery performance. Here, we propose a garnet-type intercalation cathode active material, MgSi(MoO), for high-performance Mg-ion batteries.

Impact of N-Substituent and p of Azole Rings on Fuel Cell Performance and Phosphoric Acid Loss.

The influence of N-substituent and p of azole rings has been investigated for the performance of high-temperature polymer electrolyte membrane fuel cells (HT-PEMFCs). Imidazole, benzimidazole, and triazole groups were functionalized on the side chains of poly(phenylene oxide), respectively. Each azole group is categorized by their N-substituent into two types: unsubstituted and methyl-substituted azoles.

Amplification of EBNA-1 through a single-plasmid vector-based gene amplification system in HEK293 cells as an efficient transient gene expression system.

Our previous work showed that there is a limitation in the use of dihydrofolate reductase (dhfr)/methotrexate (MTX)-mediated gene amplification systems in dhfr-non-deficient HEK293 cells, as endogenous dhfr may interfere with the amplification process. In the present study, we successfully generated Epstein-Barr virus nuclear antigen-1 (EBNA-1)-amplified HEK293 cells in a dhfr-non-deficient HEK293 cell background using a single-plasmid vector-based gene amplification system with shRNA targeting the 3'-UTR of endogenous dhfr. The introduction of this shRNA efficiently downregulated the expression of endogenous dhfr in the HEK293 cells without affecting exogenous dhfr expression.

Tunable in-plane thermal conductivity of a single PEDOT:PSS nanotube.

Understanding the mechanism of thermal energy transport in a single nanotube (NT) is essential for successfully engineering nanostructured conducting polymers to apply to thermoelectrics or flexible electronic devices. We report the characterization of the in-plane thermal energy transport in a single poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) NT via direct measurement of the in-plane thermal conductivity (κ). We also demonstrate that the in-plane κ of PEDOT:PSS NT can be tuned within the range of 0.

Defect-Assisted Contact Property Enhancement in a Molybdenum Disulfide Monolayer.

Contact engineering for two-dimensional (2D) transition metal dichalcogenides (TMDCs) is crucial for realizing high-performance 2D TMDC devices, and most studies on contact properties of 2D TMDCs have mainly focused on Fermi level unpinning. Here, we investigated electrical and photoelectrical properties of chemical vapor deposition (CVD)-grown molybdenum disulfide (MoS) monolayer devices depending on metal contacts, Ti/Pt, Ti/Au, Ti, and Ag, and particularly demonstrated the essential role of defects in MoS in contact properties. Remarkably, MoS devices with Ag contacts show a field-effect mobility of 12.

Improved carrier injection of AlGaN-based deep ultraviolet light emitting diodes with graded superlattice electron blocking layers.

A DUV-LED with a graded superlattice electron blocking layer (GSL-EBL) is demonstrated to show improved carrier injection into the multi-quantum well region. The structures of modified EBLs are designed simulation. The simulation results show the carrier behavior mechanism of DUV-LEDs with a single EBL (S-EBL), graded EBL (G-EBL), and GSL-EBL.

Differential expression of microRNAs in recombinant Chinese hamster ovary cells treated with sodium butyrate using digital RNA counting.

Sodium butyrate (NaBu) is an efficient supplement for increasing recombinant protein production in Chinese hamster ovary (CHO) cell culture. To elucidate the effects of NaBu on miRNA expression profile in recombinant CHO (rCHO) cells, differentially expressed miRNAs in NaBu-treated rCHO cells were assessed by NanoString nCounter analysis. This result showed that eight mature mouse miRNAs (let-7b, let-7d, miR-15b, miR-25, miR-27a, miR-99a, miR-125a-5p, and miR-125b-5p) were differentially expressed.

Co-amplification of EBNA-1 and PyLT through dhfr-mediated gene amplification for improving foreign protein production in transient gene expression in CHO cells.

Despite the relatively low transfection efficiency and low specific foreign protein productivity (q) of Chinese hamster ovary (CHO) cell-based transient gene expression (TGE) systems, TGE-based recombinant protein production technology predominantly employs CHO cells for pre-clinical research and development purposes. To improve TGE in CHO cells, Epstein-Barr virus nuclear antigen-1 (EBNA-1)/polyoma virus large T antigen (PyLT)-co-amplified recombinant CHO (rCHO) cells stably expressing EBNA-1 and PyLT were established using dihydrofolate reductase/methotrexate-mediated gene amplification. The level of transiently expressed Fc-fusion protein was significantly higher in the EBNA-1/PyLT-co-amplified pools compared to control cultures.

Recovery Mechanism of Degraded Black Phosphorus Field-Effect Transistors by 1,2-Ethanedithiol Chemistry and Extended Device Stability.

Black phosphorus (BP) has drawn enormous attention for both intriguing material characteristics and electronic and optoelectronic applications. In spite of excellent advantages for semiconductor device applications, the performance of BP devices is hampered by the formation of phosphorus oxide on the BP surface under ambient conditions. It is thus necessary to resolve the oxygen-induced degradation on the surface of BP to recover the characteristics and stability of the devices.

Origin of the emergence of higher T than bulk in iron chalcogenide thin films.

Fabrication of epitaxial FeSeTe thin films using pulsed laser deposition (PLD) enables improving their superconducting transition temperature (T ) by more than ~40% than their bulk T . Intriguingly, T enhancement in FeSeTe thin films has been observed on various substrates and with different Se content, x. To date, various mechanisms for T enhancement have been reported, but they remain controversial in universally explaining the T improvement in the FeSeTe films.

Multistate Models on Pleural Effusion after Allogeneic Hematopoietic Stem Cell Transplantation.

A multistate model is more complicated than competing risk models and composed of finite number of states and transitions between states. Unlike competing risk models, this model has the ability to assess the effect of occurrence order of time-to-event data. Pleural effusion (PE) is a severe complication that often occurs after allogeneic hematopoietic stem cell transplantation (HSCT).

Enhanced photovoltaic performance of polymer-filled nanoporous Si hybrid structures.

We propose a novel hybrid structure for improving the efficiency of crystalline silicon solar cells. By employing first-principles calculations, we demonstrate that ordered, nanoporous silicon (np-Si), when filled with polythiophene (PT) inside the pores, exhibits a substantially enhanced absorption coefficient compared to both np-Si and the bulk, which makes the np-Si/PT heterojunction a superior light absorbing material. In addition, the PT-filled porous structure forms a staggered gap, or type II, heterojunction at the interfaces, where the valence band maximum and conduction band minimum of the composite reside on PT and np-Si, respectively.

Classification-based quantitative analysis of stable isotope labeling by amino acids in cell culture (SILAC) data.

Background And Objective: Stable isotope labeling by amino acids in cell culture (SILAC) is a practical and powerful approach for quantitative proteomic analysis. A key advantage of SILAC is the ability to simultaneously detect the isotopically labeled peptides in a single instrument run and so guarantee relative quantitation for a large number of peptides without introducing any variation caused by separate experiment. However, there are a few approaches available to assessing protein ratios and none of the existing algorithms pays considerable attention to the proteins having only one peptide hit.

Normal-Gamma-Bernoulli Peak Detection for Analysis of Comprehensive Two-Dimensional Gas Chromatography Mass Spectrometry Data.

Compared to other analytical platforms, comprehensive two-dimensional gas chromatography coupled with mass spectrometry (GC×GC-MS) has much increased separation power for analysis of complex samples and thus is increasingly used in metabolomics for biomarker discovery. However, accurate peak detection remains a bottleneck for wide applications of GC×GC-MS. Therefore, the normal-exponential-Bernoulli (NEB) model is generalized by gamma distribution and a new peak detection algorithm using the normal-gamma-Bernoulli (NGB) model is developed.

A near-zero Poisson's ratio of Si with ordered nanopores.

The Poisson's ratio νij = -ε/ε, where ε and ε (i,j = x, y, z) are applied and resulting strain, respectively, are computed from first-principles for Si with an array of cylindrical, nanometer-sized pores aligned in the z direction (nanoporous Si, or np-Si). Through density functional theory calculations, it is demonstrated that the periodic arrangement of pores introduces strong anisotropy in the Poisson's ratio of np-Si: while νyz remains close to the Poisson's ratio of the bulk, νzx and νxy exhibit an increase and a sharp decrease from the bulk value, respectively, as the volume fraction of pores (ϕ) becomes large. It is shown that the characteristic dependence of the Poisson's ratio on ϕ originates from the difference in the actual stress on np-Si, which is caused by the dissimilar surface geometry.

Shear instability in nanoporous Si.

Elastic properties of nanoporous Si (np-Si), which is composed of bulk Si containing ordered, nanometer-sized cylindrical pores, are investigated based on first-principles density functional theory calculations. By separately varying the pore size and spacing, it is demonstrated that the elastic stiffness of np-Si under the shear strain perpendicular to the pore axis turns negative when the volume fraction of pores becomes greater than a critical value. The total energy calculations reveal that the negative values in the stiffness originate from the enhanced strain energy, which leads to significant rotation in bonds near the pore surface.

Small infrared target detection by region-adaptive clutter rejection for sea-based infrared search and track.

This paper presents a region-adaptive clutter rejection method for small target detection in sea-based infrared search and track. In the real world, clutter normally generates many false detections that impede the deployment of such detection systems. Incoming targets (missiles, boats, etc.

Significant enhancement in the thermoelectric performance of strained nanoporous Si.

Increasing demand for energy with fossil fuel supplies decreasing makes it an urgent task to develop novel and cost-effective materials that can supply environmentally benign and sustainable energy. To address this important issue, in the present work we carry out a systematic study on the effect of external strain on the room-temperature thermoelectric properties of Si containing cylindrical pores in a periodic arrangement (nanoporous Si, or np-Si), based on density functional theory and the Boltzmann transport equation. Within the relaxation time approximation, it is demonstrated that the electrical conductivity (σ) and Seebeck coefficient (S) of np-Si remain unchanged from the strain-free values under biaxial or shear strain.

Impact of stoichiometry on the electronic structure of PbS quantum dots.

Although the stoichiometry of bulk lead sulfide (PbS) is exactly 1:1, that of quantum dots (QDs) can be considerably different from this crystalline limit. Employing first-principles calculations, we show that the impact of PbS QD stoichiometry on the electronic structure can be enormous, suggesting that control over the overall stoichiometry in the QD will play a critical role for improving the efficiency of optoelectronic devices made with PbS QDs. In particular, for bare PbS QDs, we find that: (i) stoichiometric PbS QDs are free from midgap states even without ligand passivation and independent of shape, (ii) off stoichiometry in PbS QDs introduces new states in the gap that are highly localized on certain surface atoms, and (iii) further deviations in stoichiometry lead to QDs with "metallic" behavior, with a dense number of energy states near the Fermi level.

Thermal transport in functionalized graphene.

We investigate the effects of two-dimensional (2D) periodic patterns of functional groups on the thermal transport in a graphene monolayer by employing molecular and lattice dynamics simulations. Our calculations show that the use of patterned 2D shapes on graphene reduces the room temperature thermal conductivity, by as much as 40 times lower than that of the pristine monolayer, due to a combination of boundary and clamping effects. Lattice dynamics calculations elucidate the correlation between this large reduction in thermal conductivity and two dynamical properties of the main heat carrying phonon modes: (1) decreased phonon lifetimes by an order of magnitude due to scattering, and (2) direction-dependent group velocities arising from phonon confinement.

Thermal transport in nanoporous silicon: interplay between disorder at mesoscopic and atomic scales.

We present molecular and lattice dynamics calculations of the thermal conductivity of nanoporous silicon, and we show that it may attain values 10-20 times smaller than in bulk Si for porosities and surface-to-volume ratios similar to those obtained in recently fabricated nanomeshes. Further reduction of almost an order of magnitude is obtained in thin films with thickness of 20 nm, in agreement with experiment. We show that the presence of pores has two main effects on heat carriers: appearance of non-propagating, diffusive modes and reduction of the group velocity of propagating modes.