Stability Range Research Articles

Stable Millivolt Range Resistive Switching in Percolating Molybdenum Nanoparticle Networks.

To overcome the limitations of the conventional Von Neumann architecture, inspiration from the mammalian brain has led to the development of nanoscale neuromorphic networks. In the present research, molybdenum nanoparticles (NPs), which were produced by means of gas phase condensation based on magnetron sputtering, are shown to be the constituents of electrically percolating networks that exhibit stable, complex, neuron-like spiking behavior at low potentials in the millivolt range, satisfying well the requirement of low energy consumption. Characterization of the NPs using both scanning electron microscopy and scanning transmission electron microscopy revealed not only pristine shape, size, and density control of Mo NPs but also a preliminary proof of the working mechanism behind the spiking behavior due to filament formations. Furthermore, electrostatics COMSOL Multiphysics simulations of the morphology of the NPs provided evidence that the stable switching is due to the as-deposited stellate Mo NPs creating high electric field strengths, while keeping them separated, not seen before in other percolating networks based on spherical NPs. Hence, our results show the working mechanism behind switching in percolating Mo NP networks and show that they are very promising for realistic neuromorphic systems.

Effect of modifiers on the stability of 1‑butyl‑3-methylimidazolium-based ionic liquids

The distinctive capabilities of 1‑butyl‑3-methylimidazolium (bmim) cation-based ionic liquids (ILs) to dissolve lignocellulosic biomass offer the potential for the development of novel green bioprocessing technologies based on their utilization as green solvents. The limited range of thermal stability of ILs necessitates the use of various co-solvents to maintain solubility. In the present study, an original approach to determine the degree of degradation of alkylimidazolium ILs was proposed, based on the application of gravimetric analysis method to determine the content of volatile degradation products and high-performance liquid chromatography-high-resolution mass spectrometry (HPLCHRMS) to determine the total degree of degradation. The proposed approach, as well as the combination of HPLCHRMS with gas chromatography-mass spectrometry (GC–MS), was employed to comprehensively characterize the impact of additives and impurities (water, dimethyl sulfoxide, hydrochloric and acetic acids, diethylamine) on the degradation of bmim acetate, chloride, and methyl sulfate during thermal treatment under typical biomass dissolution conditions (150 °C, 24 h). The presence of additives or impurities in the composition of ILs has been found to predominantly contribute to a decrease in the number of volatile compounds formed, while increasing the variety and relative content of non-volatile degradation products. The use of protic solvents and acids results in a decrease in the overall degree of degradation of ionic liquids and in the fraction of volatile compounds formed. This allows for the classification of binary mixtures based on these additives as "green" solvents at temperatures below 150 °C.

Novel Anodic TiO2 Synthesis Method with Embedded Graphene Quantum Dots for Improved Photocatalytic Activity

Photocatalytic degradation of pollutants have a high potential for sustainable and renewable uses. TiO2 is a widely studied photocatalyst due to its high chemical and photochemical stability and wide range of applications. However, the wide band gap and low capacity of photo-induced charge separation provide lower catalytic activity; thus, improvement of these properties must be found. The doping of TiO2 with other elements, such as carbon nanoparticles (CNP) in a quantum dot form, offers a promising pathway to improve the aforementioned properties. In addition, in situ doping methods should be investigated for practical scalability, as they offer the advantage of integrating dopants directly during material synthesis, ensuring a more uniform distribution and better interaction between the dopant and the host material, in turn leading to more consistent photocatalytic properties. Current technologies primarily involve nanoparticle combinations. This work focuses on the development of a novel in situ synthesis methodology by the introduction of three different graphene-based quantum nanodots into anodic TiO2 and the following investigation of structural, morphological, and photocatalytic properties. Results indicate that the introduction of CNP allows for the shift of a set of parameters, such as the optical band gap, increased photo-induced charge carrier density of TiO2/CNP composite, and, most importantly, the change of crystalline phase composition depending on added CNP material. Research indicates that not only a higher concentration of added CNP enhances higher photocatalytic activity as tested by the degradation of methylene blue dye, but also the type of CNP determines final crystalline phase. For the first time brookite and rutile phases were obtained in anodic titania synthesized in inorganic electrolyte by introducing hydrothermally treated exfoliated graphene.

Crack growth stabilization in the eccentric three-point end-notched flexure test of solid wood using side-grooved samples

A three-point eccentric end-notched flexure (3EENF) test was conducted on Sitka spruce to characterize the Mode II resistance curve (R-curve). To extend the range for stabilized crack growth, grooves were cut along both side surfaces of the sample to reduce the region around the neutral axis. The R-curve was determined by varying the initial crack lengths, and fracture toughness values were measured at both the onset and during growth. Additionally, the effect of side grooves on stabilizing crack growth in the 3EENF test was investigated by comparing numerical simulation results with those from four-point end-notched flexure (4ENF) tests. The grooves effectively stabilized crack growth, and the stabilization range was equivalent to that of the 4ENF test when the initial crack length was appropriately determined. The grooved sample exhibited behavior indicative of a longer crack than the actual length.

Alkylation of low eutectic energy-containing carrier molecules: Design and synthesis

A novel low eutectic energy-carrying carrier molecule has been developed that satisfies three criteria: intrinsic energy, effective lowering of the melting point of other carriers, and a wide range of thermal stability. In this study, two new compounds, APAD1 and APAD2, were synthesized by alkylation of molecular side groups and their structures were confirmed by FT-IR, NMR, and XRD. The melting points of APAD1 and APAD2 were 117 °C and 97 °C, respectively, and the decomposition temperatures were 266 °C and 242 °C, respectively, which were significantly lower compared to DATNEB. This method extends the synthesis of low eutectic carrier molecules for composite casting.

Failed radial head arthroplasty treated by removal of the implant.

In patients with a failed radial head arthroplasty (RHA), simple removal of the implant is an option. However, there is little information in the literature about the outcome of this procedure. The aim of this study was to review the mid-term clinical and radiological results, and the rate of complications and removal of the implant, in patients whose initial RHA was undertaken acutely for trauma involving the elbow. A total of 11 patients in whom removal of a RHA without reimplantation was undertaken as a revision procedure were reviewed at a mean follow-up of 8.4 years (6 to 11). The range of motion (ROM) and stability of the elbow were recorded. Pain was assessed using a visual analogue scale (VAS). The functional outcome was assessed using the Mayo Elbow Performance Score (MEPS), the Oxford Elbow Score (OES), and the Disabilities of the Arm, Shoulder and Hand questionnaire (DASH). Radiological examination included the assessment of heterotopic ossification (HO), implant loosening, capitellar erosion, overlengthening, and osteoarthritis. Complications and the rate of further surgery were also recorded. The indications for removal of the implant were stiffness in five patients, aseptic loosening in five, and pain attributed to the RHA in three. The mean time interval between RHA for trauma to removal was ten months (7 to 21). Preoperatively, three patients had overlengthening of the implant, three had capitellar erosion, six had HO, and four had radiological evidence of loosening. At the final follow-up, the mean the flexion-extension arc improved significantly by 38.2° (95% CI 20 to 59; p = 0.002) and the mean arc of prono-supination improved significantly by 20° (95% CI 0 to 72.5; p = 0.035). The mean pain VAS score improved significantly by 3.5 (95% CI 2 to 5.5; p = 0.004). The mean MEPS improved significantly by 27.5 (95% CI 17.5 to 42.5; p = 0.002). The mean OES improved significantly by 9 (95% CI 2.5 to 14; p = 0.012), and the mean DASH score improved significantly by 23.5 (95% CI 7.5 to 31.6; p = 0.012). Ten patients (91%) had HO and osteoarthritis. Two patients underwent further surgery due to stiffness and pain, respectively. Simple removal of the implant at revision surgery following a failed RHA introduced following trauma provides satisfactory mid-term results with an acceptable risk of complications. Osteoarthritis, instability, and radioulnar impingement were not problems in this series.

Mechanism investigation of stability enhancement by slot on a transonic compressor

Abstract As aircraft engine blades develop towards high loads and low aspect ratios, the flow conditions in the tip region of transonic compressor rotors become more complex. The interaction between shock waves and boundary layers tends to induce fluid separation, thereby reducing the stable operating range of the rotor. To enhance the stability margin of the rotor, this study employs numerical simulation techniques to design jet slots on the rotor 37. Research results show that, without compromising the performance of the rotor, the slotted rotor can effectively enhance the stability margin of the rotor at both design and off-design speeds, with increases of 60.9% and 47.9% in surge margins compared to the prototype.

Experimental Study on Scale Effects of Kerosene Combustion in Scramjet Combustors

The combustion characteristics in two geometrically similar kerosene-fueled scramjet combustors with mass flow rates of 0.69 and 1.41 kg/s are experimentally investigated to explore the scale effects of flame stabilization at Mach 2.52 condition. As the equivalence ratio increases, the combustion usually changes from weak to intensive to blow-out mode. The weak combustion has little effect on the flow field, whereas the intensive combustion has the opposite effect. The transition combustion tends to occur between different modes. When the single injector is used, compared with the small-scale combustor, intensive combustion cannot occur in the large-scale combustor, and the flame stability range is also narrower. One probable reason is that as the combustor scale increases, the boundary layer becomes relatively thinner, resulting in a smaller low-velocity zone and a faster mainstream velocity at the downstream wall of the cavity, which is not conducive to the flame propagation upstream to form the intensive combustion. After shortening the isolator, all cases with intensive combustion in the small-scale combustor are transformed into weak combustion, further confirming the speculation. Compared to the single injector, the dual injector is required in the large-scale combustor to achieve intensive combustion and a wider flame stability range.

Stable homology isomorphisms for the partition and Jones annular algebras

We show that the homology of the Jones annular algebras is isomorphic to that of the cyclic groups below a line of gradient 12\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\frac{1}{2}$$\\end{document}. We also show that the homology of the partition algebras is isomorphic to that of the symmetric groups below a line of gradient 1, strengthening a result of Boyd–Hepworth–Patzt. Both isomorphisms hold in a range exceeding the stability range of the algebras in question. Along the way, we prove the usual odd-strand and invertible parameter results for the Jones annular algebras.

Alternative climatic steady states near the Permian-Triassic Boundary.

Due to spatial scarcity and uncertainties in sediment data, initial and boundary conditions in deep-time climate simulations are not well constrained. On the other hand, depending on these conditions, feedback mechanisms in the climate system compete and balance differently. This opens up the possibility to obtain multiple steady states in numerical experiments. Here, we use the MIT general circulation model to explore the existence of such alternative steady states around the Permian-Triassic Boundary (PTB). We construct the corresponding bifurcation diagram, taking into account processes on a timescale of thousands of years, in order to identify the stability range of the steady states and tipping points as the atmospheric CO2 content is varied. We find three alternative steady states with a difference in global mean surface air temperature of about 10°C. We also examine how these climatic steady states are modified when feedbacks operating on comparable or longer time scales are included, namely vegetation dynamics and air-sea carbon exchanges. Our findings on multistability provide a useful framework for explaining the climatic variations observed in the Early Triassic geological record, as well as some discrepancies between numerical simulations in the literature and geological data at PTB and its aftermath.

A Tunable and Switchable Multi-Wavelength Erbium-Doped Fiber Ring Laser Enabled by Adjusting the Spectral Fringe Visibility of a Mach-Zehnder Fiber Interferometer

This paper presents a tunable, switchable multi-wavelength emission from an erbium-doped fiber ring laser, enabled by adjusting the spectral fringe visibility of a fiber interferometer filter. The filter is formed with specially designed concatenated tapered fibers to configure a Mach-Zehnder fiber interferometer (MZFI). The laser emission is highly flexible and reconfigurable, allowing for tuning between single- and dual-wavelength operation. The laser can switch sequentially from one up to six wavelengths by fixing the curvature and adjusting the polarization state. The lasing emission is generated over a stable wavelength range between 1559.59 nm and 1563.54 nm, exhibiting an optical signal-to-noise ratio (OSNR) exceeding ~35 dB. The performance of amplitude and wavelength fluctuations were evaluated, indicating an appropriate stability of ~3 dB and a shift less than 0.1 nm within a 45 min period at room temperature. A detailed comparison with the literature is given.

Unveiling the Role of Filler Characteristics in Enhancing the High-Voltage Performance of Succinonitrile-Based Solid-State Lithium-Metal Batteries.

For exploiting high-energy lithium-metal batteries, it is of utmost importance to develop electrolytes that possess exceptional ionic conductivity and an extensive electrochemical stability range. In this study, 3D PAN nanofibers and polymer electrolytes incorporating various inorganic fillers with different Lewis acid-base properties were fabricated. PAN@Al-SSE exhibits exceptional ionic conductivity (0.48 mS·cm-2 at room temperature), a high Li+ transference number (0.41), and a wide electrochemical window (5.26 V). The device is able to operate stably in Li symmetric cells for more than 1000 h under a potential of 0.03 V under a current density of 0.2 mA·cm-2. Besides, the groundbreaking technology equips high-voltage Li-LiCoO2 solid-state batteries with exceptional cycling performance (91.3% and 82.1% retention after 100 cycles at 0.2 and 1 C, respectively) at room temperature. Mechanistic studies indicate that the Lewis acid-base properties of surface fillers are instrumental and crucial to form a stable solid-electrolyte interphase layer. γ-Al2O3, in particular, with more Lewis acid sites, ensures the dissociation of LiTFSI and induces the excessive decomposition and polymerization of succinonitrile. There exists an equilibrium effect between dissociation and polymerization in a succinonitrile-based solid electrolyte, which plays a critical role in improving the manifestation of succinonitrile-based solid-state lithium cells, especially under high-voltage conditions.

Aqueous Supercapacitor with Wide-Temperature Operability and over 100,000 Cycles Enabled by Water-in-Salt Electrolyte.

Supercapacitors are crucial in renewable energy integration, satellite power systems, and rapid power delivery applications for mitigating voltage fluctuations and storing excess energy. Aqueous electrolytes offer a promising solution for low-cost and safe supercapacitors. However, they still face limitations in cycle life and wide-temperature range performance. Here, we present a symmetric supercapacitor utilizing activated carbon electrodes and a "water-in-salt" electrolyte (WiSE) based on lithium perchlorate. The WiSE electrolyte exhibits an expanded electrochemical stability window, endowing the aqueous supercapacitor with remarkable stability and long cycle life of over 100,000 cycles at 500 mA g-1 with more than 91% capacity retention. Moreover, the supercapacitor demonstrates good rate capability and wide temperature operability ranging from -20 to 80 °C. The use of high concentrations of salt in the aqueous electrolyte contributes not only to the enhancement of supercapacitor performance and cycle life but also to the temperature stability range, enabling all-season operability.

Ordered PdBi Alloys for High‐Performance CO2 Electroreduction and Enhanced Formic Acid Selectivity

AbstractElectrocatalytic conversion of CO2 to formic acid (HCOOH) represents a promising approach for storing renewable energy and addressing the challenges of hydrogen storage and transportation. Palladium (Pd) is the only known metal capable of achieving this process at nearly zero overpotential. However, its practical applications are severely limited by hydrogen evolution reaction (HER) competition and CO poisoning. Bimetallic alloys, especially intermetallics with ordered structures, offer an effective way to optimize performance due to their unique catalytic properties. Here, PdBi alloys are synthesized with ordered structures and adjustable ratios of active sites for efficient CO2 electroreduction to HCOOH. The o‐PdBi2 alloy effectively suppresses both HER competition and CO production during the CO2 reduction process, achieving ≈95% HCOOH selectivity across a wide range of current densities and excellent stability at industrial‐level current densities. Additionally, the ordered structure facilitates high selectivity maintenance while mitigating overpotential, resulting in a cell voltage of only 2.65 V at 200 mA cm−2. These findings provide a pathway for the practical application of Pd‐based catalysts in CO2 electroreduction.

The Design and Performance Analysis of a 15 g/mol Helium–Xenon Mixture Centrifugal Compressor

One of the primary parts of a closed Brayton cycle that uses a helium–xenon mixture as the working medium is a centrifugal compressor. Nowadays, there has been minimal research on the theoretical underpinnings and design procedures of a helium–xenon mixture centrifugal compressors, and the internal flow mechanisms remain poorly understood. In this study, we present a redesign of the 15 g/mol helium–xenon centrifugal compressor originally developed by Bruno M, utilizing a helium–xenon mixture as the working fluid to enhance compressor performance and facilitate an in-depth analysis of the internal flow dynamics. The findings indicate a significant expansion of the stable operating range of the redesigned compressor under identical outlet conditions, with a 33.27% increase in flow margin and substantial improvements in the pressure ratio. Furthermore, under consistent inlet conditions, at an operational flow rate of 0.8657 kg/s, the redesigned compressor exhibits a pressure ratio that is 2.11% greater than that of the original design, along with a variable efficiency increase of 1.1%.

Sensitive and Selective Determination of Benzidine by Synthesized tragacanth-poly (Acrylic acid-co-acrylamide-GQD) Hydrogel Nanocomposite as a Highly Stable Fluorescent Probe.

Benzidine is known as a toxic and highly carcinogenic substance, so its determination is an essential issue. Until now, no effective and stable fluorescent probe based on hydrogel nanocomposite has been reported for the determination of this substance. In this work, for the first time, the synthesis and use of tragacanth-poly (acrylic acid-co-acrylamide-GQD) hydrogel nanocomposite (H-GQD) as a novel, high-stable, and selective fluorescence hydrogel nanocomposite for the identification of benzidine is reported. To achieve the maximum responsiveness of this hydrogel nanocomposite to determine benzidine, various parameters such as pH, ionic strength, hydrogel nanocomposite concentration, sensitivity, and selectivity were investigated. The results of the investigations showed that the synthesized H-GQD has excellent stability, selectivity, and linearity range of 0.3 - 12 ppm with a limit of detection of 0.098 ppm. The results of the investigation of real water samples showed that the H-GQD has excellent recovery in the range of 93.3 - 106.6%. Finally, we believe that this H-GQD as a new and highly stable fluorescent probe can be a starting point for its application in various fields and industries to identify benzidine in water samples.

Hydrodynamics and operation of a multistage fluidized bed with particles of super-high density

High-density particles are commonly used in fluidized bed reactors in uranium recycling processes of nuclear industry, where high fluidization quality (i.e. low gas-solids contacting efficiency) is difficult to achieve, resulting in various problems such as reduced conversion, low product selectivity, stronger equipment vibration and bad operating stability, etc. The objective of this study was to validate the feasibility and advantages of a multistage fluidized bed in processing a super-high-density powder. Wolfram carbide powder of true density of 15630 kg/m3 was used in a cold-model counter-current three-stage fluidized bed with downcomers. Stability of operation, operating range and hydrodynamics were systematically studied. The fluidization quality and operating stability were also compared with a single-stage conical fluidized bed of similar diameter and same solids inventories. The experimental results demonstrated that this high-density wolfram carbide powder could be fluidized and circulated continuously at this multistage fluidized bed, but lower fluidization quality was observed and the stable operating range is narrow. Narrower stable operating range was observed at higher solids circulation rates. At corresponding operating conditions, the fluidization quality of multistage fluidized bed is significantly better than that of the conical fluidized bed with a similar solids inventory.

Production of chitinase in elicited tomato cell suspensions and its application as a biopesticide and fungicide against soil-borne pests and fungi

Soil-borne fungi and pests present significant challenges to crop production, causing diseases and reducing yields. This study explores the potential of producing chitinase from tomato cell suspension cultures and its application in controlling soil-borne fungi and pests. Tomato cell suspension cultures were established from seeds, and different elicitors—including chitin, fungal debris, and fungal metabolites—were used to optimize chitinase production. The enzyme was purified, and its physicochemical properties were characterized. Its antifungal activity was tested against various soil-borne fungi, while termiticidal activity was evaluated using four bioassay methods. Additionally, the nematicidal activity of chitinase was assessed against different stages of root-knot nematodes. Results indicated that chitin media induced the highest chitinase production and cell growth compared to other elicitors. The purified chitinase had a molecular weight of 34 kDa, with a maximum velocity (Vmax) of 0.940 μg NAG/min and a Michaelis constant of 1.236 mg colloidal chitin/mL. The turnover number (Kcat) was 1.598 μg NAG/min/mol chitinase. The enzyme exhibited a broad range of activity and stability across varying pH levels and temperatures, as well as remarkable stability under different storage times and in the presence of metal ions. Tomato-derived chitinase demonstrated superior antifungal, nematicidal, and termiticidal activities compared to common chemical fungicides and pesticides. Chitinase was successfully produced from tomato cell suspension culture in this study, highlighting its potential as a biocontrol agent for sustainable pest and disease management in agriculture.

Arthroscopic Fixation of Posterior Cruciate Ligament Tibial Bony Avulsion Fractures: The Double Suture Bridge Technique and Evaluation of Results

Background: Surgical fixation is required for displaced posterior cruciate ligament (PCL) tibial bony avulsion fractures or with fractures having grade 2 or more posterior instability. The purpose of this study is to evaluate the results of arthroscopic fixation of PCL tibial bony avulsion fractures using the double suture bridge technique. Methods: A retrospective study was done involving 24 patients having displaced PCL tibial bony avulsion fractures. The arthroscopic double suture bridge technique was used to fix these fractures. Patients were followed up for three years and assessed for knee-related symptoms, signs, Lysholm Knee Score, and satisfaction. Results: The study group consisted of 21 men and three women. Fracture union was achieved in all cases two months postoperatively. The mean Lysholm Knee Score at follow-ups of three months, six months, one year, two years, and three years was 86.6, 96.5, 98.8, 99.1, and 99.4, respectively. At the latest follow-up, all the patients were satisfied with their knee function with respect to pain, range of motion (ROM), stability, and resumption of pre-injury activity level. Conclusion: The arthroscopic double suture bridge technique is an effective method for the fixation of PCL tibial bony avulsion fractures with respect to knee stability, ROM, and resumption of pre-injury activity level.

Effect of Mixing Time Variation and Framing Time on the Quality of Coffee Grounds-based Solid Soap

The increase in public consumption of coffee has resulted in an increase in wasted coffee grounds. Coffee grounds have good content for the skin, so they can be reused as a basic ingredient in soap-making. In the soap making process, the mixing and framing stages can affect the quality of the soap. This study aims to determine the effect of mixing time of 24.5 minutes, 25 minutes, and 25.5 minutes as well as framing time of 3 days, 5 days, and 7 days on the physical and chemical quality of solid soap made from coffee grounds. The physical quality parameters observed are colour, texture, cracking, and foam power. The chemical quality parameters are foam stability, pH, moisture content, and free alkali. The method used was the questionnaire method followed by statistical analysis using the Kruskal Wallis test for physical quality tests and the experimental method followed by statistical analysis using the Two-Way ANOVA test for chemical quality tests. The results showed that all variations in mixing time and framing time had an effect on the physical and chemical quality of solid soap and there were significant differences. The panellists assessed the physical quality of the soap to be attractive, hard, with no cracks, and foamy, while the results of the chemical quality test, the soap produced is safe to use by the quality standards of solid soap with a foam stability range of 82%-97%, pH 10.3-11.8, moisture content 6%-14%, and alkali free 0.03%-0.09%.