Distinct Peaks Research Articles

The Temporal Evolution of Nonneutralized Electric Currents and the Complexity of Solar Active Regions

We study the evolution of electric currents during the emergence of magnetic flux in the solar photosphere and the differences exhibited between solar active regions of different Hale complexity classes. A sample of 59 active regions was analyzed using a method based on image segmentation and error analysis to determine the total amount of nonneutralized electric current along their magnetic polarity inversion lines. The time series of the total unsigned nonneutralized electric current, I NN,tot, exhibit intricate structure in the form of distinct peaks and valleys. This information is largely missing in the respective time series of the total unsigned vertical electric current I z . Active regions with δ-spots stand out, exhibiting a 1.9 times higher flux emergence rate and 2.6 times higher I NN,tot increase. The median value of their peak I NN,tot is equal to 3.6 × 1012 A, which is more than three times higher than that of the other regions of the sample. An automated detection algorithm was also developed to pinpoint the injection events of nonneutralized electric current. The injection rates and duration of these events were higher with increasing complexity of active regions, with regions containing δ-spots exhibiting the strongest and longest events. These events do not necessarily coincide with increasing magnetic flux, although they exhibit moderate correlation. We conclude that net electric currents are injected during flux emergence but are also shaped drastically by the incurred photospheric evolution as active regions grow and evolve.

A novel orange-red emitting K5Y(MoO4)4:Sm3+ phosphor with excellent color purity for temperature sensing and high CRI WLEDs

The novel orange-red emitting K5Y(MoO4)4:xSm3+ (KYMO:xSm3+) (1 mol% ≤ x ≤ 35 mol%) phosphors were synthesized through solid-phase reaction. The KYMO:Sm3+ phosphors were mainly analyzed for purity phase, luminescence properties, and thermostability. Under 403 nm excitation, KYMO:10 mol%Sm3+ possesses four distinct emission peaks. The dominant emission peak is situated at 645 nm, corresponding to the 4G5/2 → 6H7/2 electron transitions. With x = 10 mol%, the KYMO:xSm3+ phosphor has the optimal doping concentration. The color purity reaches as high as 99.9 %. KYMO:10 mol%Sm3+ presents good thermostability with T0.5 > 480 K and resistance to color drift (ΔE = 0.012 at 420 K). The lifetime for KYMO:10 mol%Sm3+ is 1.16 ms. The internal quantum efficiency (IQE) reaches 62.74 %. At 480 K, the maximum temperature sensing sensitivities of the FIR of I564/I599 are 5.19 × 10−4 (Sa) and 18 % (Sr). The assembled WLED displays an excellent color rendering index (CRI, Ra) of 94, Commission International de L′ Eclairage (CIE) coordinates (0.333, 0.346), and a correlated color temperature (CCT) of 5464 K. In summary, KYMO:Sm3+ phosphors possess great promise for high CRI white-light-emitting diodes (WLEDs) and potential feasibility for temperature sensing.

Seeing the Unseen: A Method to Detect Unresolved Rings in Protoplanetary Disks

While high-resolution Atacama Large Millimeter/submillimeter Array (ALMA) observations reveal a wealth of substructure in protoplanetary disks, they remain incapable of resolving the types of small-scale dust structures predicted, for example, by numerical simulations of the streaming instability. In this article, we propose a method to find evidence for unresolved, optically thick dusty rings in protoplanetary disks. We demonstrate that, in presence of unresolved rings, the brightness of an inclined disk exhibits a distinctive emission peak at the minor axis. Furthermore, the azimuthal brightness depends on both the geometry of the rings and the dust optical properties; we can therefore use the azimuthal brightness variations to both detect unresolved rings and probe their properties. By analyzing the azimuthal brightness in the test case of ringlike substructures formed by streaming instability, we show that the resulting peak is likely detectable by ALMA for typical disk parameters. Moreover, we present an analytic model that not only qualitatively but also quantitatively reproduces the peak found in the simulations, validating its applicability to infer the presence of unresolved rings in observations and characterize their optical properties and shape. This will contribute to the identification of disk regions where streaming instability (and thus planet formation) is occurring.

A novel ratiometric fluorescent nanoprobe based on “antenna effect” for discriminating leucine enantiomers

D-Leucine is a potential biomarker for diagnosing diabetes, therefore detection of D-Leu and discrimination of Leu enantiomers are of great importance. Herein, a new fluorescent nanosensor Eu-DLSiNPs was synthesized at room temperature. Based on the “antenna effect”, a chiral ratiometric fluorescent nanoprobe Eu-DLSiNPs/OTC was obtained by simple mixing with oxytetracycline (OTC). This new sensing system showed two distinctive emission peaks at 480 nm and 616 nm, respectively. The addition of D-Leu can cause the fluorescence intensity decreased at 480 nm and enhanced at 616 nm, while L-Leu has no significant effect on the emission of the nanoprobe, so the ratiometric discrimination of Leu enantiomers can be realized. The mechanism of the enantiomeric fluorescence recognition was systematically studied. This work provides a new strategy for the recognition of leucine enantiomers and will paved a new way for discriminating other important chiral compounds.

A highly thermal-stable orange red emitting La(OH)₃:Sm³⁺ phosphor for w-LED and thermal sensor dual-applications

The orange-red emitting La(OH)₃:Sm³⁺ (1–5 mol.%) phosphors are synthesized using urea-assisted solution combustion synthesis (SCS). The synthesized La(OH)₃:Sm³⁺ phosphors were validated by Rietveld refinement and X-ray diffraction (XRD) patterns and exhibit a single-phase structure, characterized by a hexagonal system with space group P63/m. At 250 nm, the phosphors display a charge transfer band (CTB) involving O2− and Sm3+, indicating intense excitation. La(OH)₃:Sm³⁺ phosphor exhibits distinctive peaks at 565, 604, 651, and 708 nm under 250 nm excitation, which correspond to the 5G₅/₂ → 6HJ (J = 5, 7, 9, 11) transitions. Among these, 604 nm exhibits the most intense emission. The optimal doping concentration of La(OH)₃:Sm³⁺ is x = 2 mol.%. Importantly, even as the temperature increases to 420 K, La(OH)₃:Sm³⁺ demonstrates exceptional thermal stability, retaining 86.38 % of its initial luminescence intensity. The La(OH)₃:2Sm³⁺ phosphor exhibits an activation energy (Ea) of 0.328 eV. The internal quantum efficiency (IQE) measures 50.09 %. The colour purity (CP) for each phosphor is calculated to be 96.50 %. Additionally, 405 nm chips are effectively used for fabricating single-coloured and white light-emitting diodes (w-LEDs). The Commission Internationale de l'Eclairage (CIE) coordinates of the packaged w-LED are (0.325, 0.350), with a high colour rendering index (CRI) of 90. These results from investigations show that orange-red emitting La(OH)₃:Sm³⁺ phosphors have potential for development lighting device materials.

Experimental study of a semi-submersible floating wind turbine with aquaculture cages under combined wind and irregular waves

The coordinated and integrated development of multiple marine industries is conducive to achieving efficient utilization of the ocean. Here, a novel semi-submersible floating wind power platform integrated with aquaculture cages is proposed. Then, model tests of the innovative floating wind-aquaculture platform (FWAP) with scaling ratio of 1/40 are carried out. Four sea conditions (below rated, rated, cut out and 50-year sea states) and three incident angles of combined wind and waves (0 deg, 90 deg and 180 deg) are considered in the tests. Correspondingly, three typical motion responses of the FWAP, the acceleration response of the wind turbine and the representative mooring line tension are analyzed. The experimental results show that one obvious response peak is mainly found in the response amplitude operator (RAO) curves for the in-plane motion of the new FWAP, including surge, sway and yaw. While for out-of-plane motions including heave, roll and pitch, the RAO curves show two distinct response peaks. Notably, as the environmental conditions progress from below rated to rated, cut out, and finally to 50-year extreme sea state, the motion response of the FWAP becomes increasingly pronounced. Furthermore, the acceleration of the wind turbine under rated and cut out conditions is significantly large, which can be attributed to the effect of rotor rotation. While the maximum mooring line tension in the FWAP is observed at the 50-year sea state, the maximum average tension occurs at the rated condition. The response power spectra of the new FWAP reveal the presence of multiple frequency components. Additionally, the nets can act as an excited or damping effect on the motion of the FWAP, the acceleration of the wind turbine and the mooring line system, depending on the variation of the sea conditions or the incident angle. This study can provide reference for the design improvement and engineering application of such new FWAP.

The impact of mechanical vibration at cathode on hydrogen yields in water electrolysis

This study investigates the utilization of mechanical vibration to enhance the hydrogen evolution reaction (HER) in electrolysis processes. By varying the force magnitude and frequency of mechanical vibration, significant improvements in HER efficiency were observed. Specifically, the mechanical vibration-assisted electrolysis with a hitting frequency of 3 hits per second and 157.2698 Kg. m−2 hitting force improved the HER current density by 128 % compared to untreated water electrolysis. Linear sweep voltammetry (LSV) data for the graphite electrode revealed a distinct reduction peak at 1 V, indicating a favorable electrochemical reduction reaction influenced by mechanical vibration. The frequency of mechanical vibration significantly impacted the LSV response, with variations in current values across different conditions. Mechanistically, mechanical vibration disrupted intermolecular forces, facilitating better electrode-bubble interactions and accelerating reaction kinetics. Additionally, changes in pH levels induced by mechanical vibration further enhanced HER efficiency. These results suggest that integrating mechanical vibration into electrolysis systems significantly improves HER performance, contributing to the advancement of more efficient and sustainable hydrogen production technologies, which are crucial for achieving net-zero emission targets.

Phenolic syringyl end groups in 13C-enriched hardwoods detected and quantified by solid-state NMR

While syringyl units are the most abundant monolignols in hardwood lignin, their phenolic (i.e. hydroxyl) end group concentration has not been measured. In two uniformly 13C-enriched young hardwoods, from beech and oak, the syringyl units were quantitatively investigated by advanced solid-state 13C NMR. Small signals of OH-terminated syringyl units were resolved in spectrally edited two-dimensional 13C–13C NMR spectra of the two hardwoods. Their distinct peak positions predicted based on literature data were validated via the abundant OH-terminated syringyl units in hydrolyzed 13C-beechwood. In a two-dimensional 13C–13C exchange spectrum with diagonal-ridge suppression, a well-resolved peak of phenolic syringyl units was observed at the characteristic C–H peak position of syringyl rings, without significant overlap from guaiacyl peaks. Accurate 13C chemical shifts of regular and end-group syringyl units were obtained. Through spectrally edited 2D NMR after 1H inversion recovery, phenols of condensed tannin complexed with arginine were carefully analyzed and shown to overlap minimally with signals from phenolic syringyl units. The local structure and resulting spin dynamics of ether (chain) and hydroxyl (end-group) syringyl units are nearly the same, enabling quantification by peak integration or deconvolution, which shows that phenolic syringyl end groups account for 2 ± 1 % of syringyl units in beechwood and 5 ± 2 % in oakwood. The observed low end-group concentration needs to be taken into account in realistic molecular models of hardwood lignin structure.

Fabrication of MoS2 nanoparticle dispersions using ultrasonic methods: synthesis techniques and optical characterization

This study outlines the process of preparing a dispersion of MoS2 nanoparticle from micron sized MoS2 powder using ultrasonic methods. The optical characteristics of this dispersion were investigated using optical measurement techniques. N-methyl-2-pyrrolidone is chosen as the dispersion solvent due to its surface energy closely matching that of MoS2. Consequently, the dispersion that ensued exhibits commendable stability. The MoS2 dispersion underwent analysis through EDX, scanning electron microscopy, and transmission electron microscopy techniques to examine the correlation between the size of the MoS2 nanoparticles and the morphology of the dispersion. The dispersion color intensifies with the increase in the wavelength. A He-Cd laser with a wavelength of 325 nm was used to stimulate and generate the matching light source for the generated samples to leverage the photoluminescent attribute of MoS2 nanoparticles within the range of less than 100 nm. In the Raman measurement graph, distinct peaks can be observed in the generated nanoparticles, providing evidence of their material qualities. The surface morphology of the optical microscopic image was assessed using ultra-spectral imaging technology, allowing for the measurement and acquisition of the associated wavelength spectrum. The particle size in the dispersion was measured using the dynamic light scattering technique. These tests demonstrate that the process can be fine-tuned by adjusting parameters, such as ultrasonic oscillation time and centrifugal time. This process can also yield MoS2 nanoparticle dispersions in various sizes, each exhibiting distinct photoluminescence characteristics corresponding to the excited light wavelength.

Optimizing dyeing parameters for sustainable wool dyeing using quinoa plant components with antibacterial properties

This study focuses on the sustainable utilization of Quinoa plant components, particularly its leaves, as a waste agricultural material for natural dyeing applications. Two distinct Quinoa genotypes, Titicaca and Giza, were selected for their natural dyeing properties. UV-VIS absorption spectra of Quinoa colorant extracts provided insights into their chemical composition, revealing distinctive peaks indicative of betalains (400–450 nm), chlorophyll (600–650 nm), carotenoids (400–500 nm), and aromatic amino acids (250–280 nm). Wool samples dyed with different plant parts such as flowers, leaves, and stalks exhibited distinct yellow hue, with leaves demonstrating the highest color strength. Metal mordants such as iron (II) sulphate, copper sulphate, and tin (II) chloride influenced color outcomes, highlighting their role in tailoring final appearance. Fastness properties of dyed wool samples were evaluated, with leaves showing moderate staining resistance and good light fastness. Additionally, antibacterial properties of leaves of Giza Quinoa variety were assessed, showing promising activity against Staphylococcus aureus. The antibacterial properties of fabrics dyed with the leaf extract by mordanting method with different metal salt mordants, particularly Fe, Cr, and Cu, exhibited significant enhancement. These results highlight the multifaceted benefits of Quinoa plant components in sustainable natural dyeing and textile applications, emphasizing their potential for eco-friendly practices in the textile industry.

Enhancing photovoltaic applications through precipitating agents in ITO/CIS/CeO2/Al heterojunction solar cell

In this groundbreaking study, we successfully synthesized both cerium oxide and copper indium sulphate nanoparticles via co-precipitation method and the same is spray coated on ITO substrate by Jet Nebulizer Spray Pyrolysis (JNSP) technique. A comprehensive characterization of the structural, morphological and Photo-diode properties was conducted using a range of advanced techniques. X-ray diffraction revealed a superior mono-crystalline cubic fluorite structure with a preferred orientation along the (111) plane, indicating exceptional crystal quality. Scanning electron microscopy and transmission electron microscopy images showed the formation of disk-shaped particles with sharp rounded edges, averaging ∼ 5 nm in size. Fourier transform infrared spectroscopy identified the phonon band envelope of the metal oxide (CeO2) network at 848 cm−1 while photoluminescence spectroscopy revealed blue and blue-green emission in the visible spectrum. Thermogravimetric-differential thermal analysis exhibited a total weight loss of 19.52 % with four distinct exothermic and endothermic peaks. X-ray photoelectron spectroscopy confirmed the presence of Ce and O elements, with a minor amount of carbon absorbed from the atmosphere and revealed the dominant occurrence of Ce4+ and minority occurrence of Ce3+. The maximum power conversion efficiency of 0.23 % was achieved for samples prepared using NH3 precipitant making them highly suitable for photovoltaic applications. This work paves the way for future research in optimizing cerium oxide nanoparticles for high-performance photovoltaic devices potentially leading to breakthroughs in renewable energy harvesting.

Structural Evolution of Small-Sized Phosphorus-Doped Boron Clusters: A Half-Sandwich-Structured PB15 Cluster.

The present study is a theoretical investigation into the structural evolution, electronic properties, and photoelectron spectra of phosphorus-doped boron clusters PBn0/- (n = 3-17). The results of this study revealed that the lowest energy structures of PBn- (n = 3-17) clusters, except for PB17-, exhibit planar or quasi-planar structures. The lowest energy structures of PBn (n = 3-17), with the exceptions of PB7, PB9, and PB15, are planar or quasi-planar. The ground state of PB7 has an umbrella-shaped structure, with C6V symmetry. Interestingly, the neutral cluster PB15 has a half-sandwich-like structure, in which the P atom is attached to three B atoms at one end of the sandwich, exhibiting excellent relative and chemical stability due to its higher second-order energy difference and larger HOMO-LUMO energy gap of 4.31 eV. Subsequently, adaptive natural density partitioning (AdNDP) and electron localization function (ELF) analyses demonstrate the bonding characteristics of PB7 and PB15, providing support for the validity of their stability. The calculated photoelectron spectra show distinct characteristic peaks of PBn- (n = 3-17) clusters, thus providing theoretical evidence for the future identification of doped boron clusters. In summary, our work has significant implications for understanding the structural evolution of doped boron clusters PBn0/- (n = 3-17), motivating further experiments regarding doped boron clusters.

Comparative analysis: particle size and bactericidal efficacy of zinc oxide nanoparticles with aloe vera gel versus aloe vera gel-honey

In the realm of nanoscience, the inherent antibacterial potential of nanoparticles (NPs) stands as an alluring prospect for the development of pharmaceutical interventions. Yet, conventional chemical and physical NPs fabrication methods pose environmental and safety concerns. The aim of this study is to greenly-synthesize zinc oxide nanoparticles (ZnO NPs) using aloe vera gel (AVG) and aloe vera gel-honey (AVG-honey) under different reactant-to-chemical reductant (or precursor-to-reducing agent) ratio conditions, facilitated by sonication. Structural and optical characteristics of synthesized ZnO NPs were explicated through Fourier Transformation Infrared Spectroscopy (FTIR) and Ultraviolet-visible Spectroscopy (UV–vis). Concurrently, x-ray diffraction (XRD) and Field Emission Scanning Electron Microscope (FESEM) delineated the crystalline disposition and morphological behaviors. The antibacterial susceptibility of ZnO NPs against Methicillin-resistant Staphylococcus aureus (MRSA) and Klebsiella Pneumoniae (K. pneumoniae) was investigated using the disc diffusion method. The structures of biosynthesized ZnO NPs were confirmed through distinctive peaks in FTIR and UV–vis spectra. XRD unveils hexagonal wurtzite crystallinity, while FESEM captured distinct morphologies, which are spherical and rice-shaped, in ZnO NPs/AVG, while ZnO NPs/AVG-honey revealed micro-size spherical structures surrounded by numerous tiny lumps. Notably, ZnO NPs/AVG at a 1:6 ratio exhibits a 26.5 nm size, showcasing superior antibacterial efficacy against MRSA (ZOI = 12 mm) and K. pneumoniae (ZOI = 13 mm) compared to other reactant-to-chemical reductant ratios and ZnO NPs/AVG-honey. In conclusion, the study revealed that ZnO NPs synthesized solely using AVG exhibited finer particle sizes and slightly enhanced antibacterial efficacy compared to ZnO NPs formulated with a combination of AVG and honey. This outcome shows that utilization of two reducing agents will contribute to large size of nanoparticles, thus reduce the efficiency of the antibacterial susceptibility. Moreover, the concentration ratios of reactants-to-chemical reductants emerged as crucial determinants in the nanoparticle synthesis process.

Mechanical, Thermal and Morphological Characterization of Graphene/Al2O3‐Reinforced Epoxy Hybrid Nanocomposites

AbstractThis work investigates the hybrid nanocomposites manufactured by direct mixing by dispersing varying weight percentages (wt.%) of graphene nanoparticles (GNPs) and Al2O3 NPs in epoxy resin. Their properties are then obtained using various mechanical (tensile, flexural, impact, and hardness) and thermal (thermogravimetric) analyses. Furthermore, their microstructure and functional groups are studied by SEM and FTIR, respectively. The hybrid nanocomposite, which contains 1.5 wt.% GNPs and 8.5 wt.% Al2O3 NPs, has excellent mechanical properties. Compared to a composite without GNPs, the tensile strength, flexural strength, impact strength, and shore D hardness improve by 95.12, 90.01, 171.43, and 19.75%, respectively. It is also found that hybrid nanocomposite exhibits enhanced thermal stability as GNPs increase, particularly at lower wt.% of Al2O3. The SEM of tensile fractured specimens of GNPs/Al2O3 epoxy hybrid nanocomposites reveals prominent failure mechanisms, including agglomeration of GNPs and debonding between the GNPs/Al2O3 and epoxy. The FTIR spectroscopy analysis reveals distinctive spectral peaks indicating successful incorporation of Al2O3 and GNPs into the epoxy‐based composite, with observed peaks corresponding to functional groups and bonds characteristic of each component. These findings suggest that the manufactured nanocomposite holds promise as a component in structural applications, particularly in automobiles, aerospace components, and sports equipment.

Annual gametogenic development of the Asiatic hard clam, Meretrix meretrix, collected from the west coast of Moheshkhali Island, Cox's Bazar, Bangladesh

AbstractWe investigated the annual gametogenic development of the Asiatic hard clam, Meretrix meretrix, collected from the west coast of Moheshkhali Island, Cox's Bazar, Bangladesh, by using biometry and histology through monthly sampling from July 2018 to June 2019. After biometric measurements, cross sections were cut for histology to determine the sex and gonadal maturity of the clams. Condition index (CI) showed two distinct peaks in July and December, which indicated that clams were ripe during these months, and a subsequent decrease in CI reflected spawning, which was consistent with histology. Our study revealed a biannual spawning cycle of the clams and gametogenesis starting in October and June. Spawning occurred from February to May and July to September. Maturity index (MI) showed two distinct peaks in July (3.50) and January (3.60) when most of the clams were in late developing or ripe stages. A gradual increase in temperature from annual minima in conjunction with decreasing salinity levels may trigger spawning in February, but spawning in July was initiated when salinity levels increased from annual minima. The data could be used by resource managers for the conservation of this commercial species and to time harvesting for the best quality clams without interrupting spawning activity.

Ensemble Feature Selection for Clustering Damage Modes in Carbon Fiber‐Reinforced Polymer Sandwich Composites Using Acoustic Emission

Acoustic emission (AE) serves as a noninvasive technique for real‐time structural health monitoring, capturing the stress waves produced by the formation and growth of cracks within a material. This study presents a novel ensemble feature selection methodology to rank features highly relevant with damage modes in AE signals gathered from edgewise compression tests on honeycomb‐core carbon fiber‐reinforced polymer. Two distinct features, amplitude and peak frequency, are selected for labeling the AE signals. An ensemble‐supervised feature selection method ranks feature importance according to these labels. Using the ranking list, unsupervised clustering models are then applied to identify damage modes. The comparative results reveal a robust correlation between the damage modes and the features of counts and energy when amplitude is selected. Similarly, when peak frequency is chosen, a significant association is observed between the damage modes and the features of partial powers 1 and 2. These findings demonstrate that, in addition to the commonly used features, other features, such as partial powers, exhibit a correlation with damage modes.

Microstructural modification and enhanced mechanical properties in Zr50-Ti50 alloy via low temperature electron wind force annealing

This study investigates the microstructural transformations and associated property enhancements in a Zr50-Ti50 alloy annealed at only 120 °C with low duty cycle current pulses. Microanalysis with electron backscatter diffraction (EBSD) and X-ray diffraction (XRD) show the formation of alpha lath structure, typically observed in much higher thermal annealing temperatures. EBSD and XRD analyses revealed the formation and/or growth of the lath structure, with notable changes in pole distributions and the appearance of a distinct peak at 52.5° in the XRD spectrum. The lath structure is quantified using FiJi weka segmentation machine learning technique. Nanoindentation data showed an increase in the average hardness from ∼7 to ∼8 GPa and a corresponding increment in the reduced modulus from 127 to 148 GPa. The observed increase in low-angle grain boundaries (LAGBs) from 4% to 12% further complements the findings, suggesting a complex interplay of microstructural features contributing to the overall improvement in the mechanical properties. The proposed low temperature annealing technique demonstrates the predominant role of the electron wind force for tailoring the microstructure and mechanical performance of ZrTi alloys, providing insights that could have implications for the broader field of materials engineering.

Identification of coke species on Fe/USY catalysts used for recycling polyethylene into fuels.

The Fe/USY catalyst used for converting plastic waste into fuels faces coking problems. A comprehensive understanding of coke distribution and structure is crucial for catalyst design, enabling resistance to coke deposition and facilitating regeneration. In this study, we analyze the coke deposition on Fe/USY catalysts after catalytic pyrolysis of polyethylene for fuel oil, and present insights into the coke distribution over the metal and acid sites, as well as its specific molecular structure. The coke distributes over both the metal and acid sites, exhibiting distinct TPO peaks corresponding to metal-site coke (370 °C) and acid-site coke (520 °C). The total coke yields range from 2.0% to 2.4%, with distribution on metal and acid sites dependent on Fe loading and acidity. Structurally, the coke is highly-condensed, containing more than four aromatic rings with limited alkyl groups. The acid-site coke is more condensed than the metal-site coke, showing lower H/C ratios (0.5-0.75) relative to the acid-site coke (0.75-0.9). Identified by MALDI-TOF mass analysis, the predominant molecular structures of the coke located on metal and acid sites are illustrated. The metal-site cokes typically exhibit 4-7 aromatic rings, while the acid-site cokes display even greater condensation with 5-12 aromatic rings.

CuMn2O4 spinel electrodes: effect of the hydrothermal treatment duration on electrochemical performance

CuMn2O4 (CMO) thin films are produced using a simple hydrothermal method. The influence of reaction duration on the electrodes’ electrochemical performance is investigated. XRD data shows improved crystal structure after 24-h reaction time, with a crystallite size of 12.17 nm. Distinct vibrational peaks associated with Cu–O and Mn–O are observed in the ATR-FTIR spectra, corroborating the spinel formation after 24 h. XPS analysis shows a compositional shift over time, starting with copper hydroxide at 12 h, evolving into a mix of copper and manganese oxides, hydroxides, and oxyhydroxides by 18 h, and achieving the desired spinel composition by 24 h. Microscopic analysis reveals CMO is arranged as small sheet structures, with 4.95 ± 2.92 µm in length after 24-h reaction. The CMO24h electrode displays a maximum specific capacitance of 1187.50 Fg−1 at a scan rate of 1 mVs−1 in 1 M Na2SO4 electrolyte. The electrochemical performance of the synthesized CMO electrodes reveals a high potential for energy storage applications.

Designing silver nanoparticles impregnated acacia and tragacanth gum based copolymeric hydrogels for drug delivery applications

The current study investigates the utilization of gum acacia (GA) & tragacanth gum (TG) for the synthesis of silver nanoparticles (NPs) and their subsequent incorporation into hydrogels for potential applications in drug delivery (DD). Cefoperazone, an antibiotic drug, was encapsulated into hydrogels to enhance their antimicrobial activity. Copolymers were characterized by UV–Vis, TEM, FESEM, AFM, XPS, XRD, FTIR, TGA and DSC techniques. UV–Vis spectroscopy revealed the formation of NPs at a wavelength of 436 nm with an optical density of 2.65. TEM images depicted AgNPs with an average size of 37.29 ± 7.25 nm with their uniform distribution. XRD analysis demonstrated distinct crystalline peaks at 2θ = 38.34o, 43.80o, 64.60o and 77.42o attributed to AgNPs. XPS peaks observed at 368 & 374 eV, corresponding to the 3d5/2 and 3d3/2 modes of silver, respectively, confirmed the incorporation of AgNPs in the polymer matrix. Hydrogels demonstrated pH responsive sustained release of cefoperazone. The diffusion mechanism was non-Fickian and described by the Higuchi kinetic model. In the DPPH assay, copolymers exhibited a 32.36 % inhibition of free radicals, whereas in the F–C reagent assay, antioxidant activity was measured as 22.25 μg equivalent of gallic acid. The copolymers displayed blood compatible nature, as evidenced from haemolysis (2.11 ± 0.03 %) and thrombogenicity (74.71 ± 1.63 %) results. The interactions of copolymer with intestinal membrane attributed to mucoadhesive properties and required detachment force of 55.30 ± 2.80 mN to separate from the biological membrane. Growth of E. coli, P. aeruginosa and S. aureus bacteria was inhibited by copolymers with and without antibiotic drug. These characteristic properties of copolymers make them ideal materials for DD carriers.