Rational Design of Naphthol Groups Functionalized Bipolar Polymer Cathodes for High Performance Alkali-Ion Batteries.

Redox-active organic compounds gather significant attention for their potential application as electrodes in alkali ion batteries, owing to the structural versatility, environmental friendliness, and cost-effectiveness. However, their practical applications of such compounds are impeded by insufficient active sites with limited capacity, dissolution in electrolytes, and sluggish kinetics. To address these issues, a naphthol group-containing triarylamine polymer, namely poly[6,6'-(phenylazanediyl)bis(naphthol)] (poly(DNap-OH)) is rationally designed and synthesized, via oxidative coupling polymerization. It is capable of endowing favorable steric structures that facilitate fast ion diffusion, excellent chemical stability in organic electrolytes, and additional redox-active sites that enable a bipolar redox reaction. By exploiting these advantages, poly(DNap-OH) cathodes demonstrate remarkable cycling stability in both lithium-ion batteries (LIBs) and potassium-ion batteries (PIBs), showcasing enhanced specific capacity and redox reaction kinetics in comparison to the conventional poly(4-methyltriphenylamine) cathodes. Overall, this work offers insights into molecular design strategies for the development of high-performance organic cathodes in alkali-ion batteries.

Nonreciprocal Transport in a Rashba Ferromagnet, Delafossite PdCoO2.

Rashba interfaces yield efficient spin-charge interconversion and give rise to nonreciprocal transport phenomena. Here, we report magnetotransport experiments in few-nanometer-thick films of PdCoO2, a delafossite oxide known to display a large Rashba splitting and surface ferromagnetism. By analyzing the angle dependence of the first- and second-harmonic longitudinal and transverse resistivities, we identify a Rashba-driven unidirectional magnetoresistance that competes with the anomalous Nernst effect below the Curie point. We estimate a Rashba coefficient of 0.75 ± 0.3 eV Å and argue that our results qualify delafossites as a new family of oxides for nanospintronics and spin-orbitronics, beyond perovskite materials.

Spatially Controlled Octahedral Rotations and Metal-Insulator Transitions in Nickelate Superlattices.

The properties of correlated oxides can be manipulated by forming short-period superlattices since the layer thicknesses are comparable with the typical length scales of the involved correlations and interface effects. Herein, we studied the metal-insulator transitions (MITs) in tetragonal NdNiO3/SrTiO3 superlattices by controlling the NdNiO3 layer thickness, n in the unit cell, spanning the length scale of the interfacial octahedral coupling. Scanning transmission electron microscopy reveals a crossover from a modulated octahedral superstructure at n = 8 to a uniform nontilt pattern at n = 4, accompanied by a drastically weakened insulating ground state. Upon further reducing n the predominant dimensionality effect continuously raises the MIT temperature, while leaving the antiferromagnetic transition temperature unaltered down to n = 2. Remarkably, the MIT can be enhanced by imposing a sufficiently large strain even with strongly suppressed octahedral rotations. Our results demonstrate the relevance for the control of oxide functionalities at reduced dimensions.

Polymer Electrolyte Membranes Containing Functionalized Organic/Inorganic Composite for Polymer Electrolyte Membrane Fuel Cell Applications.

To mitigate the dependence on fossil fuels and the associated global warming issues, numerous studies have focused on the development of eco-friendly energy conversion devices such as polymer electrolyte membrane fuel cells (PEMFCs) that directly convert chemical energy into electrical energy. As one of the key components in PEMFCs, polymer electrolyte membranes (PEMs) should have high proton conductivity and outstanding physicochemical stability during operation. Although the perfluorinated sulfonic acid (PFSA)-based PEMs and some of the hydrocarbon-based PEMs composed of rationally designed polymer structures are found to meet these criteria, there is an ongoing and pressing need to improve and fine-tune these further, to be useful in practical PEMFC operation. Incorporation of organic/inorganic fillers into the polymer matrix is one of the methods shown to be effective for controlling target PEM properties including thermal stability, mechanical properties, and physical stability, as well as proton conductivity. Functionalization of organic/inorganic fillers is critical to optimize the filler efficiency and dispersion, thus resulting in significant improvements to PEM properties. This review focused on the structural engineering of functionalized carbon and silica-based fillers and comparisons of the resulting PEM properties. Newly constructed composite membranes were compared to composite membrane containing non-functionalized fillers or pure polymer matrix membrane without fillers.

Imaging and Harnessing Percolation at the Metal-Insulator Transition of NdNiO3 Nanogaps.

Competition between coexisting electronic phases in first-order phase transitions can lead to a sharp change in the resistivity as the material is subjected to small variations in the driving parameter, for example, the temperature. One example of this phenomenon is the metal-insulator transition (MIT) in perovskite rare-earth nickelates. In such systems, reducing the transport measurement area to dimensions comparable to the domain size of insulating and metallic phases around the MIT should strongly influence the shape of the resistance-temperature curve. Here we measure the temperature dependence of the local resistance and the nanoscale domain distribution of NdNiO3 areas between Au contacts gapped by 40-260 nm. We find that a sharp resistance drop appears below the bulk MIT temperature at ∼105 K, with an amplitude inversely scaling with the nanogap width. By using X-ray photoemission electron microscopy, we directly correlate the resistance drop to the emergence and distribution of individual metallic domains at the nanogap. Our observation provides useful insight into percolation at the MIT of rare-earth nickelates.

Control of formation of viscoelastic droplets and distribution of nano-inclusions in functional deposition for lithium-sulfur batteries.

The electrospray process produces micro/nanodroplets for various applications such as thin and uniform coatings, drug carriers and mass spectrometry. In this paper, we study the spray processes of viscoelastic jets using simulations and experiments. In discretized modeling, the jet is perturbed with axisymmetric instability and the growth of this instability causes the jet to break into droplets. For the experiments, a solution of polyvinyl alcohol in water is sprayed and is visualized using a high-speed camera. The droplet size distribution is studied from simulations with experiments for three spray cases: electrospray, air spray, and air-controlled electrospray. Our simulations and experiments reveal that the electric field is effective in reducing the droplet size, while air flow offers more jet break-ups and thus a larger number of droplets. As a result, air-controlled electrospray where these two driving forces are synergistically combined leads to a larger number of smaller droplets than electrospray or air spray. Finally, we applied three spray processes to obtain a deposition of sulfur/mesoporous carbon/graphene/polymer binder composites as a lithium sulfur battery cathode and demonstrated that air-controlled electrospray leads to a higher capacity and rate capability than other processes, exhibiting 800 mA h g-1 at 0.5C and 600 mA h g-1 at 2C.

Spatial distribution of heavy metals in crops in a wastewater irrigated zone and health risk assessment.

Industrialization and urbanization have produced a large amount of wastewater. Part of the municipal wastewater has been used as an irrigation source in urban/suburban areas. Its utilization, although economically beneficial, can significantly deteriorate the integrity of the ecological systems (e.g., in terms of quality of soil and resulting food products). The objectives of this study are to investigate the spatial distribution and bio-accumulation of heavy metals (e.g., Cd, Co, Cr, Cu, Mn, Ni, Pb, and Zn) in food crops (and topsoil) and associated health risks of their consumption in the area of Mangla Dam, Pakistan. To this end, studies were conducted to assess the risk factors such as the bioconcentration factor (BCF), health risk index (HRI), and daily intake of heavy metals (DIM). Accordingly, there was more contamination in Mangla Dam water irrigated zone (DWI) than in the groundwater irrigated zone (GWI). Co exhibited the maximum BCF of 7.45 for Eruca sativa and 6.61 for Brassica campestris in the GWI zone. Likewise, enhanced risk to human health was seen from of Cd, Cr, and Pb in Triticum aestivum and Eruca sativa grown in the DWI zone. It is recommended that the quality profile of wastewater discharge into freshwater ecosystems should be continuously monitored and regulated.

Direct Mapping of Phase Separation across the Metal-Insulator Transition of NdNiO3.

Perovskite rare-earth nickelates RNiO3 are prototype correlated oxides displaying a metal-insulator transition (MIT) at a temperature tunable by the ionic radius of the rare-earth R. Although its precise origin remains a debated topic, the MIT can be exploited in various types of applications, notably for resistive switching and neuromorphic computation. So far, the MIT has been mostly studied by macroscopic techniques, and insights into its nanoscale mechanisms were only provided recently by X-ray photoemission electron microscopy through absorption line shifts, used as an indirect proxy to the resistive state. Here, we directly image the local resistance of NdNiO3 thin films across their first-order MIT using conductive-atomic force microscopy. Our resistance maps reveal the nucleation of ∼100-300 nm metallic domains in the insulating state that grow and percolate as temperature increases. We discuss the resistance contrast mechanism, analyze the microscopy and transport data within a percolation model, and propose experiments to harness this mesoscopic electronic texture in devices.

Development of a Novel Leak-Free Constant-Pressure Cylinder for Certified Reference Materials of Liquid Hydrocarbon Mixtures.

Liquid hydrocarbon mixtures such as liquefied petroleum gas and liquefied natural gas are becoming integral parts of the world's energy system. Certified reference materials (CRMs) of liquid hydrocarbon mixtures are necessary to allow assessment of the accuracy and traceability of the compositions of such materials. A piston-type constant-pressure cylinder (PCPC) comprising chambers for a pressurizing gas (helium) and liquid (hydrocarbons) separated by a piston can be used to develop accurate and traceable liquid hydrocarbon mixture CRMs. The development of accurate CRMs relies on the maintenance of their composition. However, a PCPC might allow hydrocarbons to leak owing to the imperfect seal of the piston. In this study, a novel leak-free bellows-type constant-pressure cylinder (BCPC) is designed and evaluated by comparison with PCPCs. Liquid hydrocarbon mixtures consisting of ethane, propane, propene, isobutane, n-butane, 1-butene, and isopentane were prepared in both types of constant pressure cylinders and then monitored to check leakages between the gas and liquid chambers. Overall, notable leakage occurred from and into both chambers in the PCPCs, whereas no leakage occurred in the BCPCs in the three months after their gravimetric preparation. The BCPCs maintained no leakage even 10 months after their preparation, whereas the PCPCs showed significantly increasing leakage during the same period.

Multidirectional Wrinkle Patterns Programmed by Sequential Uniaxial Strain with Conformal yet Nontraceable Masks.

Surface wrinkling is a promising route to control the mechanical, electrical, and optical properties of materials in a wide range of applications. However, previous artificial wrinkles are restricted to single or random orientation and lacks selectivity. To address this challenge, this study presents multidirectional wrinkle patterns with high selectivity and orientation through sequential uniaxial strain with conformal polymeric shadow masks. The conformal but nontraceable polymeric stencil with microapertures are adhered to a flat substrate prior to oxidation, which forms discrete and parallel wrinkles in confined domains without any contamination. By fully investigating the process, this study displays compound topography of wrinkles consisting of wrinkle islands and surrounding secondary wrinkles on the same surface. With this topography, various diffusion properties are presented: from semi-transparent yet diffusive films to multidirectional diffusive films, which will be available for new types of optical diffuser applications.

Influences of Si-doped graded short-period superlattice on green InGaN/GaN light-emitting diodes.

We report significant improvement in optical and electrical properties of green InGaN/GaN light-emitting diodes (LEDs) by using Si-doped graded short-period InGaN/GaN superlattice (SiGSL) formed by so called indium-conversion technique. For comparison, a conventional LED without the superlattice (C-LED) and a LED with undoped graded superlattice (unGSL-LED) were prepared, respectively. The photoluminescence (PL) intensity of the SiGSL-LED was increased more than 3 times at room temperature (RT) as compared to C-LED. The PL intensity ratios of RT to 10K for the C-LED, unGSL-LED, and SiGSL-LED were measured to be 25, 40.9, and 47.5%, respectively. The difference in carrier lifetimes between 10K and RT for the SiGSL-LED is relatively small compared to that of the C-LED, which is consistent with the variation in PL intensity. The output power of a transistor-outline type SiGSL-LED was increased more than 2 times higher than that of the C-LED.

Detection of premature ventricular contractions on a ventricular electrocardiogram for patients with left ventricular assist devices.

The ventricular electrocardiogram (v-ECG) was developed for long-term monitoring of heartbeats in patients with a left ventricular assist device (LVAD) and does not normally have the functionality necessary to detect additional heart irregularities that can progress to critical arrhythmias. Although the v-ECG has the benefits of physiological optimization and counterpulsation control, when abnormal heartbeats occur, the v-ECG does not show the distinct abnormal waveform that enables easy detection of an abnormal heartbeat among normal heartbeats on the conventional ECG. In this study, the v-ECGs of normal and abnormal heartbeats are compared with each other with respect to peak-to-peak voltage, area, and maximal slopes, and a new method to detect abnormal heartbeats is suggested. In a series of animal experiments with three porcine models (Yorkshire pigs weighing 30-40 kg), a v-ECG and conventional ECG were taken simultaneously during LVAD perfusion. Clinical experts found 104 abnormal heartbeats from the saved conventional ECG data and confirmed that the other 3159 heartbeats were normal. Almost all of the abnormal heartbeats were premature ventricular contractions (PVCs), and there was short-term tachycardia for 3 s. A personal computer was used to automatically detect abnormal heartbeats with the v-ECG according to the new method, and its results were compared with the clinicians' results. The new method found abnormal heartbeats with 90% accuracy, and less than 15% of the total PVCs were missed.

Structural Engineering of Carbon Host Derived from Organic Pigment toward Physicochemically Confinement and Efficient Conversion of Polysulfide for Lithium-Sulfur Batteries.

Lithium-Sulfur Batteries (LSBs) have attracted significant attention as promising next-generation energy storage systems. However, the commercial viability of LSBs have been hindered due to lithium polysulfides (LiPSs) shuttle effect, resulting in poor cycling stability and low sulfur utilization. To address this issue, herein, the study prepares a sulfur host consisting of micro/mesopore-enriched activated carbonaceous materials with ultrahigh surface area using organic pigment via facile one-step activation. By varying the proportion of chemical agent, the pore size and volume of the activated carbonaceous materials are manipulated and their capabilities on the mitigation of LiPSs shuttle effect are investigated. Through the electrochemical measurements and spectroscopic analysis, it is verified that structural engineering of carbon hosts plays a pivotal role in effective physical confinement of LiPSs, leading to the mitigation of LiPSs shuttle effect and sulfur utilization. Additionally, nitrogen and oxygen-containing functional groups originated from PR show electrocatalytic activation sites, facilitating LiPSs conversion kinetics. The approach can reveal that rational design of carbon microstructures can improve trapping and suppression of LiPSs and shuttle effect, enhancing electrochemical performance of LSBs.

TASL mediates keratinocyte differentiation by regulating intracellular calcium levels and lysosomal function.

Maintaining epidermal homeostasis relies on a tightly organized process of proliferation and differentiation of keratinocytes. While past studies have primarily focused on calcium regulation in keratinocyte differentiation, recent research has shed light on the crucial role of lysosome dysfunction in this process. TLR adaptor interacting with SLC15A4 on the lysosome (TASL) plays a role in regulating pH within the endo-lysosome. However, the specific role of TASL in keratinocyte differentiation and its potential impact on proliferation remains elusive. In our study, we discovered that TASL deficiency hinders the proliferation and migration of keratinocytes by inducing G1/S cell cycle arrest. Also, TASL deficiency disrupts proper differentiation process in TASL knockout human keratinocyte cell line (HaCaT) by affecting lysosomal function. Additionally, our research into calcium-induced differentiation showed that TASL deficiency affects calcium modulation, which is essential for keratinocyte regulation. These findings unveil a novel role of TASL in the proliferation and differentiation of keratinocytes, providing new insights into the intricate regulatory mechanisms of keratinocyte biology.

Thermal annealing effects on the physical properties of styrenic pentablock ionomers and their electromechanical responses.

Thermal annealing effect on the physical properties of two ionic (poly((t-butyl-styrene)-b-(ethylene-r-propylene)-b-(styrene-r-styrene sulfonate)-b-(ethylene-r-propylene)-b-(t-butyl-styrene (SSPB) pentablock copolymers with different ion exchange capacities (IEC; 1.5 and 2.0 meq/g) and their electromechanical responses in ionic polymer-metal composite (IPMC) devices have been investigated. The ionic SSPB formed the microphase-separated morphology on the several tens nanometer scale and the selectively sulfonated styrene middle blocks formed the ionic channels through which ions can pass in the membrane. The thermal annealing at a high temperature led to the well developed interconnectivity between adjacent ionic channels, and thus enhanced the ion conductivity and mechanical strength of membranes, resulting in an actuation enhancement of the SSPB-based ionic actuator.

Pyrolyzed Organic Pigment as Efficient Surface-Dominated Alkali-Ion Storage Anodes.

Carbonaceous materials have attracted as prospective anodes for rechargeable alkali-ion batteries. In this study, C.I. Pigment Violet 19 (PV19) was utilized as a carbon precursor to fabricate the anodes for alkali-ion batteries. During thermal treatment, the generation of gases from the PV19 precursor triggered a structural rearrangement into nitrogen- and oxygen-containing porous microstructures. The anode materials fabricated from pyrolyzed PV19 at 600 °C (PV19-600) showed outstanding rate performance and stable cycling behavior (554 mAh g-1 over 900 cycles at a current density of 1.0 A g-1) in lithium-ion batteries (LIBs). In addition, PV19-600 anodes exhibited reasonable rate capability and good cycling behavior (200 mAh g-1 after 200 cycles at 0.1 A g-1) in sodium-ion batteries (SIBs). To define the enhanced electrochemical performance of PV19-600 anodes, spectroscopic analyses were employed to reveal the storage mechanism and kinetics of the alkali ions in pyrolyzed PV19 anodes. A surface-dominant process in nitrogen- and oxygen-containing porous structures was found to promote the alkali-ion storage ability of the battery.

The Influence of Styrene Content in Solution Styrene Butadiene Rubber on Silica-Filled Tire Tread Compounds.

In tire tread applications, achieving enhanced abrasion resistance, wet grip, and rolling resistance is crucial for optimizing overall performance. To realize improvements in these attributes for silica-filled tire tread compounds, it becomes imperative to improve the dispersity of silica filler by investigating the effect of each component in the tire tread compound. In this work, we study the effect of styrene content within solution styrene butadiene rubber (SSBR) on the properties of tire tread compounds. A higher styrene segment within SSBR contributes to increased silica dispersion and crosslink density. Thus, tire tread compounds featuring SSBR with increased styrene content not only improve physical and mechanical properties, but also enhance major characteristics tailored for tire tread applications. These findings provide valuable insights into advancing the reinforced performance of tire tread compounds through the strategic utilization of SSBR enriched in styrene content.

A Multifunctional Interlocked Binder with Synergistic In Situ Covalent and Hydrogen Bonding for High-Performance Si Anode in Li-ion Batteries.

Silicon has garnered significant attention as a promising anode material for high-energy density Li-ion batteries. However, Si can be easily pulverized during cycling, which results in the loss of electrical contact and ultimately shortens battery lifetime. Therefore, the Si anode binder is developed to dissipate the enormous mechanical stress of the Si anode with enhanced mechanical properties. However, the interfacial stability between the Si anode binder and Cu current collector should also be improved. Here, a multifunctional thiourea polymer network (TUPN) is proposed as the Si anode binder. The TUPN binder provides the structural integrity of the Si anode with excellent tensile strength and resilience due to the epoxy-amine and silanol-epoxy covalent cross-linking, while exhibiting high extensibility from the random coil chains with the hydrogen bonds of thiourea, oligoether, and isocyanurate moieties. Furthermore, the robust TUPN binder enhances the interfacial stability between the Si anode and current collector by forming a physical interaction. Finally, the facilitated Li-ion transport and improved electrolyte wettability are realized due to the polar oligoether, thiourea, and isocyanurate moieties, respectively. The concept of this work is to highlight providing directions for the design of polymer binders for next-generation batteries.

Low-Index Facet Polyhedron-Shaped Binary Cerium Titanium Oxide for High-Voltage Aqueous Zinc-Vanadium Redox Flow Batteries.

Aqueous zinc-vanadium hybrid redox flow battery systems are an efficient strategy to address the problems of low voltage and high cost of conventional all-vanadium redox flow batteries. However, the low electrochemical activity of carbon-based electrodes toward a vanadium redox reaction limits the performance of redox flow batteries. In this study, polyhedral binary cerium titanium oxide (Ce2/3TiO3, CTO) is synthesized using molten salt synthesis. CTO is fabricated by adjusting the temperature and composition. Notably, the prepared CTO obtained at 1000 °C shows the highest catalytic activity for a VO2+/VO2+ redox reaction. Further, CTO is prepared as a composite electrocatalyst and applied to a high-voltage aqueous zinc-vanadium redox flow battery. The cell adopts an alkali zinc electrolyte containing a Zn/[Zn(OH)4]2- redox pair and exhibits a high operating voltage of 2.26 V. Remarkably, a zinc-vanadium redox flow battery using the composite electrocatalyst exhibits a high energy density of 42.68 Wh L-1 at 20 mA cm-2 and an initial voltage efficiency of 90.3%. The excellent cell performance is attributed to structural defects caused by A-site deficiency in the perovskite oxide structure as well as oxygen vacancies resulting from the low valence state of the metal ion, which enhance the catalytic activity of the vanadium ions.

Voltage control of magnetism in Fe3-xGeTe2/In2Se3 van der Waals ferromagnetic/ferroelectric heterostructures.

We investigate the voltage control of magnetism in a van der Waals (vdW) heterostructure device consisting of two distinct vdW materials, the ferromagnetic Fe3-xGeTe2 and the ferroelectric In2Se3. It is observed that gate voltages applied to the Fe3-xGeTe2/In2Se3 heterostructure device modulate the magnetic properties of Fe3-xGeTe2 with significant decrease in coercive field for both positive and negative voltages. Raman spectroscopy on the heterostructure device shows voltage-dependent increase in the in-plane In2Se3 and Fe3-xGeTe2 lattice constants for both voltage polarities. Thus, the voltage-dependent decrease in the Fe3-xGeTe2 coercive field, regardless of the gate voltage polarity, can be attributed to the presence of in-plane tensile strain. This is supported by density functional theory calculations showing tensile-strain-induced reduction of the magnetocrystalline anisotropy, which in turn decreases the coercive field. Our results demonstrate an effective method to realize low-power voltage-controlled vdW spintronic devices utilizing the magnetoelectric effect in vdW ferromagnetic/ferroelectric heterostructures.