Stability Properties Research Articles

Mathematical formulation of the machine learning backpropagation network and regression modelling of the chemical stability and thermal properties of PLA/HKUST-1 fabricated porous membranes

Mathematical formulation of the machine learning backpropagation network and regression modelling of the chemical stability and thermal properties of PLA/HKUST-1 fabricated porous membranes

Probing marginal stability in the spherical p = 2 model

Abstract In this paper, we investigate the marginally stable nature of the low-temperature trivial spin-glass phase in spherical p = 2 spin glass by perturbing the system with three different kinds of non-linear interactions. In particular, we compare the effect of three additional dense four-body interactions, namely ferromagnetic couplings, purely disordered couplings and couplings with competing disordered and ferromagnetic interactions. Our study, characterized by the effort to present in a clear and pedagogical way the derivation of all the results, shows that the marginal stability property of the spherical spin glass depends in fact on which kind of perturbation is applied to the system. In general, a certain degree of frustration is needed in the additional terms in order to induce a transition from a trivial to a non-trivial spin-glass phase. On the other hand, the addition of generic non-frustrated interactions does not destabilize the trivial spin-glass phase.

DFT calculations of pressure effects on structural stability, optoelectronic and thermoelectric properties of SrZrO3

DFT calculations of pressure effects on structural stability, optoelectronic and thermoelectric properties of SrZrO3

Biomechanical Comparison of Spacer Pin Fixation to Two Established Methods of Tibial Tuberosity Transposition Stabilization in Dogs.

The aim of this cadaveric study was to compare the biomechanical outcomes of three methods of stabilization for tibial tuberosity transposition to treat medial patellar luxation: a complete osteotomy with a two-pin and tension band wire (TBW) fixation (TBW group), a partial osteotomy with a two-pin fixation (2 Pin group), and a partial osteotomy with a spacer pin fixation (Spacer Pin group). Thirty medium to large-sized canine cadaveric tibiae were dissected and randomly assigned to one of three groups: TBW, 2 Pin, and Spacer Pin groups. The patellar ligaments were loaded in tension until ultimate failure. Ultimate failure force and mode of failure were documented, stiffness was calculated, and the results were compared statistically between the three treatment groups. There were not any significant differences in ultimate failure force or stiffness between groups. All groups predominantly failed by patellar ligament failure, with distal tibial crest fracture/displacement being the second-most common mode in the 2 Pin and Spacer Pin groups. The mechanical properties of the spacer pin stabilization were not different from the TBW and 2 Pin groups. The spacer pin technique could be an alternative way to stabilize tibial tuberosity following tibial tuberosity transposition with a partial osteotomy based on this cadaveric load-to-failure model.

One‐Step Green‐Synthesized UiO‐66‐NH2 /Alginate Composite Hydrogels with Improved Methylene Blue Adsorption

AbstractZirconium‐based metal‐organic frameworks (Zr‐MOFs) represent an important class of MOFs with high stability and outstanding properties, the green preparation and shaping of which are still challengeable works to hinder their real‐world applications. In this presentation, UiO‐66‐NH2 MOFs were in‐situ grown accompanied by alginate (Alg) hydrogelation under aqueous conditions, achieving UiO‐66‐NH2/Alg composite hydrogels. Relevant characterizations demonstrate the in‐situ generated UiO‐66‐NH2 MOFs were evenly distributed in hydrogel networks by attaching on Alg fiber surfaces. The network structure became denser, but both specific surface area and pore volume were augmented due to the presence of MOFs, which in turn increased active sites to interact with adsorbates. Thus, the adsorption capacity to methylene blue (MB) of composite hydrogels became higher with more dosage of MOF ligand, and the pH sensitivity of Alg adsorption to MB in the pH range of 4 to 10 was eliminated. Furthermore, the study of adsorption kinetics and isotherm reveals MB adsorption on the obtained hydrogels belong to rate controlling chemisorption mechanism. In summary, this manuscript presents a facile approach to realizing the green synthesis and shaping of Zr‐MOFs by one‐step compositing of UiO‐66‐NH2 with Alg‐based hydrogels in aqueous system, achieving MOFs‐based composite hydrogels with enhanced MB adsorption.

Pressure-induced structural stability, metallization and optoelectronic properties of transition metal chalcogenide BaTiS3

The pressure effects on the structural stability, metallization and optoelectronic properties of transition metal chalcogenide BaTiS3 are investigated by performing ab-initio calculations. Our calculations show that BaTiS3 has a hexagonal structure at ambient pressure, which matches well with the available experimental values. As pressure increases, a transition from hexagonal to orthorhombic phase occurs at around 10.8 GPa. The band structure and density of states of hexagonal BaTiS3 have been calculated and analysed. Moreover, the effect of pressure on the optical properties has been studied in terms of dielectric function as well as absorption coefficient, reflectivity and extinction coefficient. The application of hydrostatic pressure has shifted the maximum absorption toward the visible range, revealing that hexagonal BaTiS3 can be used for high pressure optoelectronic applications.

Nonspecific Yet Selective Interactions Contribute to Small Molecule Condensate Binding.

Biomolecular condensates are essential in various cellular processes, and their misregulation has been demonstrated to underlie disease. Small molecules that modulate condensate stability and material properties offer promising therapeutic approaches, but mechanistic insights into their interactions with condensates remain largely lacking. We employ a multiscale approach to enable long-time, equilibrated all-atom simulations of various condensate-ligand systems. Systematic characterization of the ligand binding poses reveals that condensates can form diverse and heterogeneous chemical environments with one or multiple chains to bind small molecules. Unlike traditional protein-ligand interactions, these chemical environments are dominated by nonspecific hydrophobic interactions. Nevertheless, the chemical environments feature unique amino acid compositions and physicochemical properties that favor certain small molecules over others, resulting in varied ligand partitioning coefficients within condensates. Notably, different condensates share similar sets of chemical environments but at different populations. This population shift drives ligand selectivity toward specific condensates. Our approach can enhance the interpretation of experimental screening data and may assist in the rational design of small molecules targeting specific condensates.

An Investigation on the High-Temperature Stability and Tribological Properties of Impregnated Graphite

Impregnated graphite is a common material for friction pairs in aeroengine seals, especially at high temperatures. For the convenience of the application of graphite materials in aeroengines, an SRV-4 tribometer and a synchronous thermal analyzer are employed to study the tribological properties and thermal stability of pure, resin-impregnated, metal-impregnated, and phosphate-impregnated graphite against stainless steel from room temperature to 500 °C. The results indicate that impregnations can improve the wear resistance and thermal stability of graphite at high temperatures. Compared with other impregnated graphite materials, the resin-impregnated graphite shows a good friction coefficient and poor wear rate and thermal stability over 300 °C, due to the degradation and oxidation of the resin-and-graphite matrix. The metal- and phosphate-impregnated graphite materials exhibit excellent wear resistance and thermal stability under 500 °C as a result of the protection of the impregnations, while the average friction coefficient of the metal-impregnated graphite is much greater than the phosphate-impregnated graphite, and even reaches 2.14-fold at 300 °C. The wear rates for the graphite impregnated with resin, metal, and phosphate are 235 × 10−7, 7 × 10−7, and 16 × 10−7 mm3N−1m−1 at 500 °C, respectively. Considering all aspects, the phosphate-impregnated graphite exhibits excellent tribological properties and thermal stability.

Mitigating effect of chitosan-coated zinc oxide nanoparticles on cryopreservation-induced DNA damage in human spermatozoa

Zinc, an essential micronutrient, is an important mediator of sperm function. Supplementation of zinc oxide nanoparticle (ZnONPs) to semen cryopreservation medium has shown beneficial effects on sperm function, mainly due to its antioxidant and membrane stabilization properties. However, the ZnONPs are known to be membrane impermeable. In the current study, we explored the beneficial properties of membrane permeable zinc oxide nanoparticles on semen cryopreservation outcome. For the study, 52 liquefied human ejaculates were cryopreserved with chitosan-coated ZnONPs and stored in liquid nitrogen for one week. Samples were thawed and assessed for the sperm functional characters and DNA integrity. Significantly higher motility (P < 0.05), prolonged survival (P < 0.05) and lower DNA damage (P < 0.05) was observed in spermatozoa of semen samples cryopreserved with chitosan-coated ZnONPs. In conclusion, the presence of chitosan-coated ZnONPs in the ejaculate prior to cryopreservation increases the survival and decreases DNA damage without compromising with the functional competence of spermatozoa.

Robust Adaptive Extremum Seeking Control Without Persistence of Excitation: Theory to Experiment

ABSTRACTIn this article, we develop a novel adaptive extremum‐seeking control (AdESC) algorithm with robustness guarantees and without persistence of excitation (PE). Specifically, this builds on a proportional‐integral (PI)‐like parameter estimator. A zeroth‐order optimization framework is used, where the optimizer/agent can only query the numerical value of the cost function at the current coordinate given an unmodeled bounded disturbance. Since parameter estimation plays a decisive role in the stability and convergence properties of AdESC algorithm, it is also well established in the existing literature that to ensure parameter convergence a stringent PE condition is required. Here, we eliminate the need for a stringent PE condition by utilizing a novel set of weighted integral filter dynamics, while ensuring sufficient richness using a milder condition, called initial excitation (IE). Moreover, to validate the robustness guarantees towards unmodeled bounded disturbance, a detailed Lyapunov function based analysis is performed to establish the closed‐loop stability and convergence in the form of uniform ultimate boundedness (UUB). Furthermore, an experimental study using a unicycle wheeled mobile robot (WMR) is carried out as a proof‐of‐concept considering disturbance and disturbance‐free scenarios.

Molecular modeling analyses of functionalized cellulose.

Functionalization of cellulose with nanomaterials and functional groups is essential for enhancing its properties for specific applications, such as flexible sensors and printed electronics. This study employs Hartree Fock (HF) and Density Functional Theory (DFT) calculations to investigate the vibrational spectra of cellulose, identifying DFT: B3LYP/3-21g** as the optimal model aligning with experimental spectra. Using this model, we examined the impact of functionalizing cellulose with various groups (OH, NH2, COOH, CH3, CHO, CN, SH) and graphene oxide (GO) on its electronic properties. The results indicate that cellulose functionalized with GO (Cellulose-GO) has the lowest bandgap energy (0.1687eV), and improvements in reactivity, stability, and electronic properties were confirmed through Molecular Electrostatic Potential (MESP) and Total Dipole Moment (TDM) analyses. The spectrum of Density of States (DOS) for the cellulose functionalized with different groups shows several peaks, indicating various energy levels where electronic states are concentrated. The Projected Density of States (PDOS) analysis reveals how different functional groups affect the electronic structure of cellulose. Moreover, the (Cellulose-GO) composite was characterized using an Attenuated Total Reflection Fourier Transform Infrared (ATR-FTIR) spectrometer, revealing interaction through the OH group of CH2OH, as indicated by a new band at 1710cm-1, consistent with theoretical predictions. Overall, this study demonstrates that functionalization with GO enhances cellulose's responsiveness, degradation, and electrical properties, making it suitable for applications in flexible electronic devices and protective barriers against corrosion.

Synthesis of cefixime loaded PCL/HPMC blend nanoparticles: a controlled release study and in vitro anti-bacterial evaluation

Aim To enhance cefixime’s effectiveness and address drug delivery challenges like concentration at the site, dose, and time, present study investigated the impact of polymer blends on cefixime’s in vitro release profile. Methods Cefixime-loaded nanoparticles were prepared via a modified solvent evaporation method, forming a W/O/W double emulsion. Characterisation included FT-IR, zeta potential, TGA, TEM, and XRD, with in vitro studies and kinetic models used to analyse the release mechanism. Results The PH-4 nanoparticle formulation (80:20 PCL/HPMC, 0.5% PVA) achieved an 81% loading rate, no adverse effects, and a controlled release of 84.66%±2.53 over 30 days. It showed stable physicochemical properties, with in vitro antibacterial tests revealing inhibition zones of 27.4 ± 2.12 mm for E. coli and 17.2 ± 2.23 mm for S. aureus at 12 hours. Conclusion Based on the findings, developed nanoparticulate system containing PCL/HPMC demonstrates its efficacy and safety as a controlled drug delivery method for antibiotics like cefixime.

Static-spun mesoporous silica-coated CsPbBr3 blue fibres: synthesis and fluorescence properties.

Due to their excellent properties, blue CsPbBr3 quantum dots show great promise for full-colour display and lighting applications. This study used acetonitrile, a polar solvent, to post-treat CsPbBr3 quantum dots, resulting in a blue shift to 453nm. To enhance stability, these quantum dots were encapsulated within the pore structure of mesoporous silica. A flexible luminescent fiber material was prepared using poly (lactic acid) (PLA) as the substrate, demonstrating improved hydrophobicity and stable optical properties. The material exhibited a contact angle of 99.7° and maintained 82.2% of its fluorescence intensity after 30days at room temperature. These findings highlight its significant potential for optical applications.

High‐Efficiency Electrochemical Desalination: The Role of a Rigid Pseudocapacitive Polymer Electrode with Diverse Active Sites

AbstractHybrid capacitive deionization (HCDI) emerges as a burgeoning electrochemical desalination technology due to the utilization of profitable pseudocapacitive reactions. Although tunable organic compounds are potential faradaic electrode materials, their insufficient active sites and high water‐solubility restrict practical HCDI applications. Herein, a pseudocapacitive organic polymer (PNDS) is proposed with diverse redox‐active sites for electrochemical deionization. The pronounced molecular aromaticity and strong π‐electron delocalization not only endow PNDS polymer with framework rigidity, but refine its electronic structure to bolster redox activity and electron affinity. As an electrode material, the PNDS polymer demonstrates a substantial pseudocapacitive capacitance of 390 F g−1 and sustains long‐term stability at 96.3% after 5000 cycles, surpassing reported Na+‐capturing organic electrodes. In‐operando monitoring techniques and theoretical calculations reveal efficient Na+ capture at the C═N and C═O redox‐active sites within the PNDS electrode during repeated electrosorption processes. As a conceptual demonstration, a high‐performance HCDI device equipped with the PNDS electrode exhibits an impressive salt removal capacity (66.4 mg g−1), a rapid removal rate (2.2 mg g−1 min−1) and stable regeneration property. More importantly, an integrated desalination system is engineered to rapidly and repeatedly treat saltwater resources for human consumption and agricultural irrigation, highlighting its promising prospects for high‐efficiency desalination applications.

Thermal/mechanical properties of cordierite synthesized using coal gangue as a refractory material

AbstractCoal gangues i a solid waste during the coal mining process and the accumulation of coal gangue will harm the environment. Therefore, solid waste utilization of coal gangue is required to reduce the environmental damage. In this paper, cordierite ceramics are successfully prepared via a solid‐phase sintering using coal gangue, Al2O3, and MgO as raw materials. The effects of sintering temperatures on the microstructures, phase stability, and thermal properties of ceramics are investigated. The results show that the properties of cordierites prepared at 1200°C are close to those of prepared by the traditional method, and the synthesized ceramics have thermal expansion coefficients (TECs) and conductivity of 4.1–10−6 K−1 and 1.72 W·m−1 K−1 at 900°C, respectively. The sample prepared at 1200°C has good wear resistance (η) with a wear resistance coefficient of 0.507, and an excellent thermal shock resistance, which can withstand 15 times of cold and hot shocks at 1100°C without any cracks on the surface. This study systematically elucidates the thermal/mechanical properties of the synthesized cordierite, and the feasibility of using coal gangue as raw materials prepared cordierite ceramics as refractory materials. This work presents an effective solution to mitigate the challenge of coal gangue disposal.

Photothermally Active Quantum Dots in Cancer Imaging and Therapeutics: Nanotheranostics Perspective.

Cancer is becoming a global threat, as the cancerous cells manipulate themselves frequently, resulting in mutants and more abnormalities. Early-stage and real-time detection of cancer biomarkers can provide insight into designing cost-effective diagnostic and therapeutic modalities. Nanoparticle and quantum dot (QD)-based approaches have been recognized as clinically relevant methods to detect disease biomarkers at the molecular level. Over decades, as an emergent noninvasive approach, photothermal therapy has evolved to eradicate cancer. Moreover, various structures, viz., nanoparticles, clusters, quantum dots, etc., have been tested as bioimaging and photothermal agents to identify tumor cells selectively. Among them, QDs have been recognized as versatile probes. They have attracted enormous attention for imaging and therapeutic applications due to their unique colloidal stability, optical and physicochemical properties, biocompatibility, easy surface conjugation, scalable production, etc. However, a few critical concerns of QDs, viz., precise engineering for molecular imaging and sensing, selective interaction with the biological system, and their associated toxicity, restrict their potential intervention in curing cancer and are yet to be explored. According to the U.S. Food and Drug Administration (FDA), there is no specific regulation for the approval of nanomedicines. Therefore, these nanomedicines undergo the traditional drug, biological, and device approval process. However, the market survey of QDs is increasing, and their prospects in translational nanomedicine are very promising. From this perspective, we discuss the importance of QDs for imaging, sensing, and therapeutic usage pertinent to cancer, especially in its early stages. Moreover, we also discuss the rapidly growing translational view of QDs. The long-term safety studies and cellular interaction of these QDs could enhance their visibility and bring photothermally active QDs to the clinical stage and concurrently to FDA approval.

Electronic properties of corundum-like Ir2O3 and Ir2O3-Ga2O3 alloys

In the hexagonal, corundum-like structure, α-Ga2O3 has a bandgap of ∼ 5.1 eV, which, combined with its relatively small electron effective mass, high Baliga's figure of merit, and high breakdown field, makes it a promising candidate for power electronics. Ga2O3 is easy to dope n-type, but impossible to dope p-type, impeding the realization of some electronic device designs. Developing a lattice-matched p-type material that forms a high-quality heterojunction with n-type Ga2O3 would open new opportunities in electronics and perhaps optoelectronic devices. In this work, we studied Ir2O3 as a candidate for that purpose. Using hybrid density functional theory calculations we predict the electronic band structure of α-Ir2O3 and compare that to α-Ga2O3, and study the stability and electronic properties of α-(IrxGa1−x)2O3 alloys. We discuss the band offset between the two materials and compare it with recently available experimental data. We find that the Ir d bands that compose the top of the valence band in α-Ir2O3 are much higher in energy than O p bands in α-Ga2O3, possibly enabling effective p-type doping. Our results provide an insight into using the Ir2O3 or Ir2O3-Ga2O3 alloys as p-type material lattice-matched to α-Ga2O3 for the realization of p–n heterojunctions.

CsPbBr3 perovskite quantum dots/p-GaN heterojunction for ultraviolet-visible spectrum photodetectors

All-inorganic perovskites have attracted increasing attention because of their strong environmental stability and excellent photoelectric properties. However, the limited spectral response range of perovskite photodetectors restricts them in practical applications. In this work, an ultraviolet–visible photodetector with a wide spectral response and a high responsivity was prepared by constructing a CsPbBr3 quantum dots (QDs)/p-GaN heterojunction. The type-II energy band alignment formed by the heterojunction is conducive to the transport of photogenerated carriers, resulting in a high responsivity. Under certain conditions, the device can obtain responsivity values of 5 A/W and 850 mA/W under 350 and 725 nm illumination, respectively, which are comparable to those of other perovskite-based photodetectors. In addition, the photoresponse mechanism of the device is revealed through first-principles calculations of the heterojunction and the device. The enhanced light absorption of the heterojunction and the special band bending under different bias voltages improve the photoelectric performance of the device. This work can provide valuable insights into high-performance photodetectors based on all-inorganic perovskite QDs heterojunctions in terms of band regulation and device performance improvement.

Sketched and Truncated Polynomial Krylov Methods: Evaluation of Matrix Functions

ABSTRACTAmong randomized numerical linear algebra strategies, so‐called sketching procedures are emerging as effective reduction means to accelerate the computation of Krylov subspace methods for, for example, the solution of linear systems, eigenvalue computations, and the approximation of matrix functions. While there is plenty of experimental evidence showing that sketched Krylov solvers may dramatically improve performance over standard Krylov methods, especially when combined with a truncated orthogonalization step, many features of these schemes are still unexplored. We derive a new sketched Arnoldi‐type relation that allows us to obtain several different new theoretical results. These lead to an improvement of our understanding of sketched Krylov methods, in particular by explaining why the frequently occurring sketched Ritz values far outside the spectral region of do not negatively influence the convergence of sketched Krylov methods for . Our findings also help to identify, among several possible equivalent formulations, the most suitable sketched approximations according to their numerical stability properties. These results are also employed to analyze the error of sketched Krylov methods in the approximation of the action of matrix functions, significantly contributing to the theory available in the current literature.

Replenish the Electron-Deficient State of Carbonyl Carbon Atoms to Achieve Stable Li-S Battery.

Carbonate-based electrolytes are widely used in Li-ion batteries (LIBs) due to their safe, stable properties and wide operating temperature range. However, the nucleophilic attack at carbonyl carbon atoms by polysulfide anions and the low solubility of lithium nitrate (LiNO3<0.1m) in carbonate-based electrolytes seriously hinder the application of lithium-sulfur (Li-S) batteries in carbonate-based electrolytes. Herein, the electrophilicity of carbonyl carbon atoms is gradually reduced through solvent molecules redesign, eliminated the attack of polysulfide anions on carbonyl carbon atoms, and also changed the intermolecular interactions in the electrolyte, improving the solubility of LiNO3 (>1.0m) and forming stable LiNxOy-containing SEI on the surface of the lithium metal. The assembled Li-S battery with these designed solvent molecules delivers an initial discharge capacity of 1251.7mAhg-1 at 0.1C. In addition, the lithium-sulfur battery assembled with the designed solvent molecule has a discharge capacity of 631mAhg-1 after 420 cycles at 0.2 C, with a capacity retention of ≈60%. Moreover, the Li||Li symmetrical cell shows stable cycle performance over 1200h at 0.5mAcm-2 and 0.5mAhcm-2.