Inherent Structural Stability Research Articles

Two-Step Preparation of Asphalt-based Porous Carbon Adsorbent with Superior C2H6/CH4 Selectivity for Ethane Recovery from Natural Gas

Efficient recovery of ethane from natural gas is of industrial importance, yet it poses considerable challenges. Herein, we report the two-step green preparation of asphalt-based carbon adsorbent AsCs with exceptional C2H6/CH4 selectivity and high capacity, where the KOH usage can be significantly reduced by 75% than conventional chemical activation processes. More importantly, the resulting AsC-0.75-900 exhibits exceptional C2H6/CH4 separation performance with the IAST selectivity of 30.74 and ethane capacity of 4.53 mmol/g at 298 K and 100 kPa. Notably, even at the low pressure of 10 kPa, its ethane uptake remains high at 2.25 mmol/g, comparable to many advanced MOFs. Molecular simulation was used to elucidate the adsorption mechanism. Fixed-bed experiments further demonstrate dynamic separation performance, achieving complete separation of a C2H6/CH4 binary mixture (10:90, v/v) at ambient condition. In addition to its superior separation performance, AsC-0.75-900 offers inherent structural stability and cost-effectiveness, positioning it a highly promising candidate for ethane recovery from natural gas.

PPy-PdO modified MXene for flexible binder-free electrodes for asymmetric supercapacitors: Insights from experimental and DFT investigations

Binder-free, flexible electrodes of V2C MXene, V2C-PPy, and V2C-PPy-PdO (a ternary composite of vanadium carbide, polypyrrole, and palladium oxide) were fabricated using a simplified, one-step electrodeposition method. A comprehensive assessment has subsequently been conducted on the microstructural and electrochemical attributes of these electrode materials when utilized in supercapacitors with a 1 M H2SO4 electrolyte. Notably, an impressive specific capacitance of 487F g−1 is achieved for V2C-PPy-PdO ternary composite at 1 A/g. This exceptional performance is due to the considerable active surface area and inherent structural stability of the host material. These factors significantly enhanced the electrochemical reaction kinetics and cyclic reversibility. Furthermore, the V2C-PPy-PdO composite demonstrated a notable specific capacitance of 250F g−1 when integrated into an asymmetric coin cell configuration alongside activated porous carbon under a current density of 1 A/g. Remarkably, it maintained an outstanding capacitance retention of 92 % across 10,000 charge–discharge cycles. Our experimental discoveries were additionally substantiated through the Density Functional Theory calculations, which unveiled that the inclusion of PdO within the V2C-PPy-PdO composite led to an augmentation of electronic states near the Fermi level. This increase in electronic states ultimately improved the quantum capacitance, rendering the V2C-PPy-PdO composite a highly promising candidate for supercapacitor applications.

In Situ, Rapid Synthesis of Carbon-Loaded High Density and Ultrasmall High Entropy Oxide Nanoparticles as Efficient Electrocatalysts.

High entropy materials offer almost unlimited catalytic possibilities due to their variable composition, unique structure, and excellent electrocatalytic performance. However, due to the strong tendency of nanoparticles to coarsen and agglomerate, it is still a challenge to synthesize nanoparticles using simple methods to precisely control the morphology and size of the nanoparticles in large quantities, and their large-scale application is limited by high costs and low yields. Herein, a series of high-entropy oxides (HEOs) nanoparticles with high-density and ultrasmall size (<5nm) loaded on carbon nanosheets with large quantities are prepared by Joule-heating treatment of gel precursors in a short period of time (≈60s). Among them, the prepared (FeCoNiRuMn)3O4-x catalyst shows the best electrocatalytic activity for oxygen evolution reaction, with low overpotentials (230mV @10mAcm-2, 270mV @100mAcm-2), small Tafel slope (39.4mVdec-1), and excellent stability without significant decay at 100mAcm-2 after 100h. The excellent performance of (FeCoNiRuMn)3O4-x can be attributed to the synergistic effect of multiple elements and the inherent structural stability of high entropy systems. This study provides a more comprehensive design idea for the preparation of efficient and stable high entropy catalysts.

Dendrite-free and anticorrosion Zn anode induced by the robust CeF3 interfacial layer

Side reactions (Zn corrosion and hydrogen evolution reactions) and uncontrollable Zn dendrites at the Zn/electrolyte interface significantly reduce the lifetime of Zn anodes, thereby limiting the practical application of aqueous Zn-based energy storage devices. Here, the robust CeF3 interfacial phase with excellent corrosion resistance was in situ constructed on the surface of Zn anode. This CeF3 interfacial phase can inhibit harmful side reactions and optimize the Zn deposition behavior, thereby enhancing the cycling stability of the Zn anode. Compared with the pure Zn electrode, the CeF3-Zn electrode demonstrated excellent corrosion resistance within a wide temperature range (25–55 °C), which can be attributed to the inherent structural stability of the CeF3 phase. Furthermore, the CeF3 interfacial phase exhibited excellent Zn2+ conductivity owing to its unique fluorine sites, which result in uniform and dense Zn deposits. Therefore, the anticorrosion, dendrite-free CeF3-Zn anode without by-product accumulation was obtained. Ultimately, the CeF3-Zn electrode exhibited outstanding cycling stability (maintaining a polarization potential below 50 mV after 3600 cycles in symmetric cells at a current density of 2 mA cm−2) and great promise for practical application (having a capacity retention rate of 60% after 3000 cycles in CeF3-Zn//AC zinc-ion capacitors at a current density of 1000 mA g−1).

Effect of soil compaction and cover crop management on soil physical quality, biomass production and corn and soybean yield

ABSTRACT No-till with cover crop (CC) has been marketed to growers as a sustainable way to increase soil quality and crop yields. Our goal was to better understand the effect of CC management strategies on crop yield and mitigation of soil compaction. The compaction treatments were: four (C4) and eight (C8) wheel passes of a tractor, and without additional compaction (C0). CCs in autumn/winter were Italian ryegrass (IR) hay, IR as CC, and mix of IR and forage radish as CC. In the spring/summer, corn and soybean were cultivated. The reduction of hydraulic conductivity (0–6 cm depth) after first season in the IR hay was 74.9% in C4 and 96.2% in C8 comparted with C0. Overall, harvested CC has limited capacity to respond to compaction, decreasing root growth (root biomass of 2191, 2753, and 3744 kg ha−1, IR hay, IR CC, and mix, respectively). Further, the negative effects of compaction on crop yield were modest, probably because of the low axle loads and contact stresses; high inherent structural stability of Oxisols; and permanent no-till and CC roots which favored soil structure stability. Future works should use higher axle loads and surface stresses and a control treatment without CC.

Surface-structure tailoring of Dendritic PtCo nanowires for efficient oxygen reduction reaction

Platinum-based alloy nanowire catalysts demonstrates great promise as electrocatalysts to facilitate the cathodic oxygen reduction reaction (ORR) of proton exchange membrane fuel cells (PEMFCs). However, it is still challenge to further improve the Pt atom utilization of Pt based nanowires featuring inherent structural stability. Herein, a new structure of PtCo nanowire with nanodendrites was developed using CO-assistance solvent thermal method. The dendrite structure with an average length of about 7 nm are characterized by a Pt-rich surface and the high-index facets of {533}, {331} and {311}, and grows from the ultra-fine wire structure with an average diameter of about 3 nm. PtCo nanowires with nanodendrites developed in this work shows outstanding performance for ORR, in which its mass activity of 1.036 A/mgPt is 5.76 times, 1.74 times higher than that of commercial Pt/C (0.180 A/mgPt) and PtCo nanowires without nanodendrites (0.595 A/mgPt), and its mass activity loss is only 18% under the accelerated durability tests (ADTs) for 5k cycles. The significant improvement is attributed to high exposure of active sites induced by the dendrite structure with Pt-rich surface with the high-index facets and Pt-rich surface. This structure may provide a new idea for developing novel 1D Pt based electrocatalysts.

Microwave solvothermal synthesis of Component-Tunable High-Entropy oxides as High-Efficient and stable electrocatalysts for oxygen evolution reaction

Transition-metal-based high-entropy oxides (HEOs) are appealing electrocatalysts for oxygen evolution reaction (OER) due to their unique structure, variable composition and electronic structure, outstanding electrocatalytic activity and stability. Herein, we propose a scalable high-efficiency microwave solvothermal strategy to fabricate HEO nano-catalysts with five earth-abundant metal elements (Fe, Co, Ni, Cr, and Mn) and tailor the component ratio to enhance the catalytic performance. (FeCoNi2CrMn)3O4 with a double Ni content exhibits the best electrocatalytic performance for OER, namely low overpotential (260 mV@10 mA cm−2), small Tafel slope and superb long-term durability without obvious potential change after 95 h in 1 M KOH. The extraordinary performance of (FeCoNi2CrMn)3O4 can be attributed to the large active surface area profiting from the nano structure, the optimized surface electronic state with high conductivity and suitable adsorption to intermediate benefitting from ingenious multiple-element synergistic effects, and the inherent structural stability of the high-entropy system. In addition, the obvious pH value dependable character and TMA+ inhibition phenomenon reveal that the lattice oxygen mediated mechanism (LOM) work together with adsorbate evolution mechanism (AEM) in the catalytic process of OER with the HEO catalyst. This strategy provides a new approach for the rapid synthesis of high-entropy oxide and inspires more rational designs of high-efficient electrocatalysts.

Hexagonal Voronoi pattern detected in the microstructural design of the echinoid skeleton.

Repeated polygonal patterns are pervasive in natural forms and structures. These patterns provide inherent structural stability while optimizing strength-per-weight and minimizing construction costs. In echinoids (sea urchins), a visible regularity can be found in the endoskeleton, consisting of a lightweight and resistant micro-trabecular meshwork (stereom). This foam-like structure follows an intrinsic geometrical pattern that has never been investigated. This study aims to analyse and describe it by focusing on the boss of tubercles—spine attachment sites subject to strong mechanical stresses—in the common sea urchin Paracentrotus lividus. The boss microstructure was identified as a Voronoi construction characterized by 82% concordance to the computed Voronoi models, a prevalence of hexagonal polygons, and a regularly organized seed distribution. This pattern is interpreted as an evolutionary solution for the construction of the echinoid skeleton using a lightweight microstructural design that optimizes the trabecular arrangement, maximizes the structural strength and minimizes the metabolic costs of secreting calcitic stereom. Hence, this identification is particularly valuable to improve the understanding of the mechanical function of the stereom as well as to effectively model and reconstruct similar structures in view of future applications in biomimetic technologies and designs.

Synthesis, Characterizations, and Electrochemical Performances of Highly Porous, Anhydrous Co0.5Ni0.5C2O4 for Pseudocapacitive Energy Storage Applications.

Electrochemical energy storage relies essentially on the development of innovative electrode materials with enhanced kinetics of ion transport. Pseudocapacitors are excellent candidates to bridge the performance gap between supercapacitors and batteries. Highly porous, anhydrous Ni0.5Co0.5C2O4 is envisaged here as a potential electrode for pseudocapacitor applications, mainly because of its open pore framework structure, which poses inherent structural stability due to the presence of planar oxalate anions (C2O42–), and active participation of Ni2+/3+ and Co2+/3+ results in high intercalative charge storage capacity in the aqueous KOH electrolyte. The Ni0.5Co0.5C2O4 electrode shows specific capacitance equivalent to 2396 F/g at 1 A/g in the potential window of 0.6 V in the aqueous 2 M KOH electrolyte by galvanostatic charge/discharge experiments. Predominant pseudocapacitive mechanism seems to operative behind high charge storage due to active participation of Ni2+/3+ and Co2+/3+ redox couple as intercalative (inner) and surface (outer) charges stored by porous anhydrous Co0.5Ni0.5C2O4 were close to high 38 and 62% respectively. Further, in full cell asymmetric supercapacitors (ASCs) in which porous anhydrous Co0.5Ni0.5C2O4 was used as the positive electrode and activated carbon (AC) was utilized as the negative electrode, in the operating potential window 1.6 V, the highest specific energy of 283 W h/kg and specific power of ∼817 W/kg were achieved at 1 A/g current rates. Even at a very high power density of 7981 W/kg, the hybrid supercapacitor still attains an energy density of ∼75 W h/kg with high cyclic stability at a 10 A/g current rate. The detailed electrochemical studies confirm higher cyclic stability and a superior electrochemical energy storage property of porous anhydrous Co0.5Ni0.5C2O4, making it a potential pseudocapacitive electrode for large energy storage applications.

Radiological follow-up of the degenerated facet joints after lateral lumbar interbody fusion with percutaneous pedicle screw fixation: Focus on spontaneous facet joint fusion

BackgroundLateral lumbar interbody fusion (LLIF) is widely used in degenerative lumbar spine surgery. Previous studies of radiographic investigations after LLIF have assessed the anterior interbody fusion rate, the changes in the segmental lumbar lordosis, efficacy of indirect neural decompression, and remodeling of the ligamentum flavum hypertrophy and spinal canal dimension, and so on. The purpose of this study was to evaluate the radiological changes in the degenerated facet joints following LLIF with bilateral percutaneous pedicle screw (PPS) fixation, focusing on spontaneous fusion. MethodsWe retrospectively analyzed 31 patients (79 surgical levels) who underwent two- or three-level LLIF with PPS fixation without direct posterior decompression and bone grafting. We assessed the fusion rate and characteristics of the facet joints’ fusion process on the preoperative, immediately postoperative, 12-month, and at least 2-year computed tomography (CT) images. On average, the last follow-up CT was performed after 30.2 months. Multivariate logistic regression analysis investigated factors related to spontaneous facet joint fusion postoperatively. ResultsThe fusion rates of the interbody and facet joints were 32.9% (26/79) and 19.0% (15/79) after 12-months and 79.7% (63/79) and 58.2% (46/79) at the final CT follow-up, respectively. Of the 46 cases with spontaneous facet fusion, three cases fused posteriorly only. Concomitant anterior interbody fusion was seen in 43/46 (93.5%) cases. Facet fusion started in a ring shape from the outermost joint edges, exposing subchondral bone without cartilage covering, and progressed to the central thicker cartilage regions. Multivariate analysis established that concomitant anterior interbody fusion (adjusted odds ratio [aOR]: 12.10, P = 0.0035) and preoperative facet joint osteoarthritis of Weishaupt Grade ≧ 1 (aOR: 4.770, P = 0.0068) were significant contributing factors to postoperative spontaneous facet fusion. ConclusionsOur study shows that spontaneous facet fusion frequently occurs after LLIF and may be an indicator of the inherent structural stability of the LLIF construct.

Mechanism and properties of rod-like Li1.2Mn0.54Ni0.13Co0.13O2 cathode material synthesized by β-MnO2 template for advanced Li-ion batteries

A rod-like Li-rich manganese layered oxide cathode material Li1.2Mn0.54Ni0.13Co0.13O2 is synthesized through β-MnO2 template by a simple solid-state reaction, and the reacting process and electrochemical properties are studied. The results show that the radial nanometer effect and inherent structural stability of β-MnO2 nanorods bring about fast chemical reaction, morphologic heredity and service toleration. The unique architecture of the rod-like Li1.2Mn0.54Ni0.13Co0.13O2 also results in superior layered structure with low cation mixing and excellent electrochemical performances. The initial discharge capacity is about 250 mAh g−1 and the capacity retention rate is about 76.0% after 80 cycles at 0.1 C current rate. When cycled at 2 C rate, the discharge capacity is as high as 175.3 mAh g−1, suggesting a good rate capability. The capacity decline is mainly attributed to the radial direction nanometer effect, structural transformation, cation mixing and surface degradation.

Improving Alkylamine Incorporation in Porous Polymer Networks through Dopant Incorporation

AbstractThe industrial scale capture of CO2 from flue gas streams is becoming an increasingly important environmental issue. However, many of the existing CO2 capture systems either have regenerative energy demands that are too high or are cost prohibitive. A promising solution is the utilization of functionalized solid sorbents, such as porous polymer networks (PPNs). PPNs are attractive due to their inherent structural stability, flexibility, high surface areas, and ability to incorporate various functional groups within the chemical scaffold. Herein, a low cost, scalable alternative to common carbon capture systems using a series of robust mesoporous melamine‐formaldehyde resins (mPMFs) loaded with active alkylamine sorbents is presented, which is dubbed as the PPN‐150 family. The variants within this material class are differentiated based on the incorporation of functionalized dopants; small molecules added at low molar percent concentrations to impart additional functionality into the PPN in order to achieve low cost noncovalent tethering of alkylamines. The cyanuric acid doped PPN‐151‐DETA (DETA = diethylenetriamine) demonstrate unique features such as improved cycling capacity and heat of adsorption. To show its scalability, PPN‐151‐DETA is successfully synthesized at the 250 g scale without loss of the sorbent properties.

A Ladder At Its Core

The ladder-core system is a novel structural system for supertall towers that was created by SOM for Tower 1 at Shum Yip Upperhills, a mixed-use development in Shenzhen, China. The system features eight megacolumns at the perimeter that form the vertical rails of the ladders on the four corners of the core. Composite coupling beams—the ladder rungs—connect the megacolumns to the interior core, creating a comprehensive lateral system that allows for unobstructed occupant views, simplicity of the floor plates, and inherent structural stability.

Integration of a diamine solvent based absorption and coal fly ash based mineralisation for CO2 sequestration

Our previous studies have revealed that diamines containing one primary amine group exhibit a superior kinetics while retaining their intrinsic high capacities towards CO2 absorption when compared with monoethanolamine. However, these diamine absorbents typically suffer from high regeneration energy due to the inherent structural stability of the formed carbamate species. In an effort to overcome this challenge, we developed a new CO2 sequestration process that integrates the CO2 absorption by a diamine solvent and the diamine regeneration as well as CO2 mineralization by CaO-rich fly ash. Herein, we found that CO2 rich diamine solutions can be chemically regenerated by fly ash with the stable cyclic performance via the CO2 absorption - mineralization experiments, and the CO2 sequestration capacity of the fly ash used in this process dominated the amine regeneration performance. The FT-IR analysis of species in the solution along with the characterizations of fly ash via SEM, EDX and XRD revealed that fly ash was effective to regenerate a diamine - 1-(2-hydroxyethyl)-4-aminopiperidine (C4) by deprotonation of C4H+, meanwhile, the CaO component in fly ash can react with CO2 in the C4 solution to produce the calcium carbonate precipitate. This approach presents a significant energy saving alternative to the traditional CO2 desorption process.

Stable hybrid perovskite MAPb(I1−xBrx)3 for photocatalytic hydrogen evolution

Hybrid organic-inorganic perovskites have been pursuing for solar/visible-driven H2 evolution from hydrohalic acid (HX) splitting, but their inherent structural stability and performance are still challenging. Herein, we report on a stable hybrid perovskite MAPb(I1−xBrx)3 (x = 0–0.20) obtained by one-pot crystallization in a mixed halide parent solution and its implementation as a newcomer photocatalyst for H2 evolution in aqueous HX solution. MAPb(I1−xBrx)3 is demonstrated to be a superior visible-light-driven photocatalyst for H2 evolution in aqueous HI/HBr solution with no Pt as a cocatalyst. An optimized MAPb(I1−xBrx)3 (x = 0.10) shows a highest H2 evolution rate of 1471 μmol h−1 g−1 under visible light (λ ≥ 420 nm) illumination, which is ˜40 times higher than that of pure MAPbI3, and the dual-halide perovskite is rather stable showing no obvious decrease in the photocatalytic activity over 60 runs (252 h). The perovskite inherent structural stability is further evidenced by XRD, UV–vis spectra and EDS elemental mapping of MAPb(I1−xBrx)3 measured after cycled photocatalytic reaction. The solar HI splitting efficiency of MAPb(I1−xBrx)3 (x = 0.10) is determined as 1.42%. The mechanism behind photocatalytic H2 evolution enhancement is elucidated by the experimental and computational methods.

Improving the structural stability of Li-rich cathode materials via reservation of cations in the Li-slab for Li-ion batteries

High-capacity Li-rich cathode materials can significantly improve the energy density of lithium-ion batteries, which is the key limitation to miniaturization of electronic devices and further improvement of electrical-vehicle mileage. However, severe voltage decay hinders the further commercialization of these materials. Insights into the relationship between the inherent structural stability and external appearance of the voltage decay in high-energy Li-rich cathode materials are critical to solve this problem. Here, we demonstrate that structural evolution can be significantly inhibited by the intentional introduction of certain adventive cations (such as Ni2+) or by premeditated reservation of some of the original Li+ ions in the Li slab in the delithiated state. The voltage decay of Li-rich cathode materials over 100 cycles decreased from 500 to 90 or 40 mV upon introducing Ni2+ or retaining some Li+ ions in the Li slab, respectively. The cations in the Li slab can serve as stabilizers to reduce the repulsion between the two neighboring oxygen layers, leading to improved thermodynamic stability. Meanwhile, the cations also suppress transition metal ion migration into the Li slab, thereby inhibiting structural evolution and mitigating voltage decay. These findings provide insights into the origin of voltage decay in Li-rich cathode materials and set new guidelines for designing these materials for high-energy-density Li-ion batteries.

Conformational Transitions of the Catalytic Domain of Heme-Regulated Eukaryotic Initiation Factor 2α Kinase, a Key Translational Regulatory Molecule

In mammalian cells, the heme-regulated inhibitor (HRI) plays a critical role in the regulation of protein synthesis at the initiation step through phosphorylation of α-subunit of the eukaryotic initiation factor 2 (eIF2). In this study we have cloned and performed biophysical characterization of the kinase catalytic domain (KD) of rabbit HRI. The KD described here comprises kinase 1, the kinase insertion domain (KI) and kinase 2. We report here the existence of an active and stable monomer of HRI (KD). The HRI (KD) containing three tryptophan residues was examined for its conformational transitions occurring under various denaturing conditions using steady-state and time-resolved tryptophan fluorescence, circular dichroism (CD) and hydrophobic dye binding. The parameter A and phase diagram analysis revealed multi-state unfolding and existence of three stable intermediates during guanidine hydrochloride (Gdn-HCl) induced unfolding of HRI (KD). The protein treated with 6 M Gdn-HCl showed collisional and static mechanism of acrylamide quenching and the constants (K(sv) = 3.08 M(-1) and K(s)= 5.62 M(-1)) were resolved using time resolved fluorescence titration. Based on pH, guanidine hydrochloride and temperature mediated transitions, HRI (KD) appears to exemplify a rigid molten globule-like intermediate with compact secondary structure, altered tertiary structure and exposed hydrophobic patches at pH 3.0. The results indicate the inherent structural stability of HRI (KD), a member of the class of stress response proteins.

Conformational characterization of human eukaryotic initiation factor 2α: A single tryptophan protein

The α-subunit of the human eukaryotic initiation factor 2 (heIF2α), a GTP binding protein, plays a major role in the initiation of protein synthesis. During various cytoplasmic stresses, eIF2α gets phosphorylated by eIF2α-specific kinases resulting in inhibition of protein synthesis. The cloned and over expressed heIF2α, a protein with a single tryptophan (trp) residue was examined for its conformational characteristics using steady-state and time-resolved tryptophan fluorescence, circular dichroism (CD) and hydrophobic dye binding. The steady-state fluorescence spectrum, fluorescence lifetimes (τ1=1.13ns and τ2=4.74ns) and solute quenching studies revealed the presence of trp conformers in hydrophobic and differential polar environment at any given time. Estimation of the α-helix and β-sheet content showed: (i) more compact structure at pH 2.0, (ii) distorted α-helix and rearranged β-sheet in presence of 4M guanidine hydrochloride and (iii) retention of more than 50% ordered structure at 95°C. Hydrophobic dye binding to the protein with loosened tertiary structure was observed at pH 2.0 indicating the existence of a molten globule-like structure. These observations indicate the inherent structural stability of the protein under various denaturing conditions.

Use of 3D β-Tricalcium Phosphate (Vitoss ® ) Scaffolds in Repairing Bone Defects

Vitoss is the most porous (90%) of a number of beta-tricalcium phosphate osteoconductive bone fillers. Its inherent limitations are those of the calcium phosphate class, being a purely osteoconductive product without inherent structural stability and with a moderate resorption rate. Currently, a number of additives, composites and related compounds are under study at various stages. In animal experiments, Vitoss performs well in comparison with other synthetic grafts, and with marrow added in various ways, it rivals autograft. Clinical efficacy is established for Vitoss as a spinal graft extender, as well as for periodontal, dental and orthopedic tumor defects. Apart from recombinant human platelet-derived growth factor, clinical data is lacking on the addition of bone marrow, stem cells and growth factors.