High Purity Research Articles

Optimization of structure, optical, magnetic, and radiation shielding properties of ZnO@xSrFe12O19 nanocomposites

In this work, the pristine ZnO, SrFe12O19 (SFO), and their nanocomposites (ZnO/x SFO: x = 1, 3 and 5%) were synthesized by co-precipitation and sonomechanical method. The x-ray diffraction data validate the preparation of ZnO, SFO, and nanocomposite samples with high phase purity. The optical band gap was calculated from UV–vis-NIR diffuse reflectance measurements, and it was modified by increasing SFO content. Adding 1, 3, and 5 wt% of SFO to the ZnO matrix showed ferromagnetic characteristics for the nanocomposites with a squareness ratio of around 0.49, which considered these nanocomposites as a magnetic semiconductor suitable for digital memory and spintronic applications. Additionally, the radiation shielding features of the prepared samples were evaluated. The shielding parameters for the studied samples were obtained using the Phy-X/PSD program. The fast neutron removal cross-section of SFO was 0.094 cm−1, the highest among the investigated samples, while the composites had similar values, about 0.083 cm−1. The results indicated that the γ--ray attenuation ability and the values of exposure buildup factor for the prepared samples were close. Therefore, ZnO, SFO, and their nanocomposites compared to stationary shielding materials (SMs), can be candidates for applications where radiation protection is needed.

Design and multi-objective optimization of hybrid process of membrane separation and electrochemical hydrogen pump for hydrogen production from biogas

A new hybrid process for hydrogen (H2) production that including membrane separation, electrochemical hydrogen pump (EHP) and steam methane reforming (SMR) was proposed. Firstly, the combination of two different membranes (PEO-CA) is applied to upgrade the biogas and capture CO2. Secondly, to avoid the toxic effect of CO on the EHP catalyst and, more importantly, to improve the H2 purity, the reforming reaction module is supplemented with water gas shift after the SMR. Finally, EHP is used to achieve high purity hydrogen. Simultaneously, the heat and power integration are considered to improve system efficiency. Sensitivity analysis, maximal information coefficient method and response surface methodology are applied to establish the correlation between objectives and parameters. Then, the second generation multi-objective non-dominated genetic algorithm (NSGA-II) is utilized to achieve minimum levelized cost of hydrogen (LCoH) and carbon emission per unit of hydrogen (ECO2). The optimized LCoH is 2.72 $/kgH2, and the ECO2 is 3.24 kgCO2e. Multi-stage membrane carbon capture process enhances CH4 conversion in SMR. The application of EHP reduces energy consumption and enhances hydrogen yield compared to PSA. The innovative use of membrane is hybridized with EHP to achieve the system intensification. The new hybrid process has a significant advantage in terms of ECO2 (37.45% reduction), although the price is higher compared to conventional biogas-to-hydrogen processes. Thus the new process is a promising low-carbon hydrogen production process from biogas.

A quantitative analysis on the effect of crystal parameters on full energy peak efficiency of a coaxial high purity Germanium detector for the energy range 50 keV-2.5 MeV

High Purity Germanium (HPGe) detectors are essential instruments in gamma-ray spectrometry, offering high sensitivity and exceptional energy resolution. The full-energy-peak (FEP) efficiency is a critical parameter that influences the accuracy of activity concentration measurements of radionuclides. This study examines the FEP efficiency of a coaxial HPGe detector, focusing on variations in crystal length, crystal radius, and crystal hole dimensions. For varying crystal lengths, the efficiency values show negligible differences at low energy (50 keV) but significant increases at higher energies, indicating that longer crystal lengths enhance efficiency. Similarly, the efficiency increases with larger crystal radii across all energy levels suggesting substantial efficiency gains even at low energies. However, variations in crystal hole radius and depth, exhibit minimal impact on FEP efficiency across all tested energy levels. These findings highlight that optimizing crystal length and radius is more crucial for changing detector efficiency compared to modifying hole dimensions, providing valuable insights for optimizing Monte Carlo models and detector design.

Enhancing interfacial stability in lithium orthosilicate/polymer blended novel hybrid solid-state electrolytes for all-solid-state lithium metal batteries

Hybrid solid-state electrolyte (HSSE) is a key component for the advancement of all-solid-state lithium metal batteries. The key challenges with the existing HSSEs are to ensure high ionic conductivity, activate dead inorganic/organic interface, and stimulate interfacial stability with electrodes. In this study, a novel HSSE is fabricated by integration of appropriately engineered end-of-life photovoltaic recycled high purity silicon derived nano size inorganic lithium orthosilicate and poly (vinylidene fluoride-co-hexafluoropropylene) polymer matrix through entrapping ionic liquid electrolytes. The obtained lithium orthosilicate-polymer blended HSSE is self-standing, soft, and flexible which delivers a low activation energy, leading a high ionic conductivity of 4.4 × 10−4 Scm−1. A critical lithium plating/stripping behaviour shows improved interfacial stability (both inorganic/organic interface and interfaces of HSSE/electrodes) under different current densities (0.05 mA cm−2 to 0.13 mA cm−2) when a drop of ionic liquid electrolyte is added, permitting cycling of an all-solid-state full cell (Li/HSSE/LiFePO4) at room temperature with high capacity (132 mAh g−1), stable cycle life and high Coulombic efficiency (initial ∼98 %; subsequent >99.5 %). Shaping the interfaces between inorganic/organic phases in the HSSE as well as the interfaces between electrodes/HSSE appears to be a workable path towards constructing very effective HSSE for the advancement of all-solid-state lithium metal batteries.

Recovery and characterization of cellulose microfibers from fallen leaves and evaluation of their potential as reinforcement agents for production of new biodegradable packaging materials

AbstractIn the present work, cellulose microfibers (CMFs) isolated from fallen autumn leaves of cherry plum (Prunus cerasifera pissardii nigra), white mulberry (Morus alba) and plane (Platanus orientalis) trees were characterized and used as reinforcement agents in sodium alginate‐based biodegradable films. Fourier transform infrared spectroscopy (FT‐IR) characterization showed that the CMFs were successfully isolated from the leaves with high purity. The extracted CMFs had a particle size ranging from 321.20 nm to 632.26 nm and negative zeta potential values (−27.33 to −21.40). The extraction yield of CMFs ranged from 19.53% to 26.00%. Incorporation of the leaf‐derived CMFs into sodium alginate based films (1%, w:w) increased their tensile strength (from 153.73 to 187.78 MPa) and elongation at break values (from 105.97% to 89.90%) and significantly decreased oxygen (from 121.46 to 75.56 meq kg‐1) and water vapor permeabilities (from 2.36 to 1.60 g mm h−1 m−2 kPa−1)(p < 0.05). Furthermore, the supplementation of CMFs into the biopolymer matrix had no significant effect on the color (L*: 85.35–85.67; a*: −0.75‐0.71; b*: 4.23–4.94) and moisture content (44.64–48.42%) of the film samples, although the thickness increased (40.33–94.66 μm). Scanning electron microscopy (SEM) images showed that CMFs were homogeneously dispersed in the film matrix. Overall, this study confirms that fallen cherry plum, white mulberry, and plane leaves are valuable sources of CMFs which could be used in the manufacturing of biodegradable nanocomposite films as reinforcement agents.

An alternative approach in the synthesis of strontium-hydroxyapatite and strontium hydroxyapatite embedded in graphitic carbon nitride nanocomposites for potential tissue engineering applications

Sr-hydroxyapatite has drawn much attention with promising applications in biomedical engineering especially in drug delivery and tissue repair. A novel protocol for the preparation of Strontium hydroxyapatite (Sr-HAP) and Strontium hydroxyapatite encapsulated by graphitic carbon nitride (Sr-HAP@gCN) with high purity and better homogeneity was adopted for potential use in orthopaedic surgeries. The physiological pathway of Strontium and calcium inside humans follow the same trend leading to the mineral deposition of the bone. In the present study, a novel attempt in synthesizing Sr-HAP and Sr-HAP@gCN by the hydrothermal method is proposed for obtaining an ideal biomaterial with potential biocompatibility and pharmacological activity. Phase identification by X-ray diffraction (XRD), Fourier transform Infra-Red spectroscopic analysis (FTIR), Electron & atomic force microscopic studies, Thermogravimetric and Raman spectroscopic analysis was performed on the prepared Sr-HAP and Sr-HAP@gCN to characterize the incorporation efficiency of Strontium. Resazurin microtiter assay and MTT assay were used to evaluate antimicrobial susceptibility and biocompatibility. The typical crystal phase of Sr-HAP and a phase change in Sr-HAP@gCN have been demonstrated with special reference to the interfacial connection between gCN and Sr-HAP through FT-IR studies. Raman spectroscopy revealed the archetypal signature of symmetric and asymmetric PO vibrations pertaining to linearity change with the addition of Strontium. The biological effect of Sr-HAP and Sr-HAP@gCN was quite significant in inducing mineralization when kept immersed in simulated body fluid (SBF) for 21 days. Promising results pertaining to antimicrobial susceptibility and biocompatibility have been proved as an encouraging choice for drug delivery applications and bone filling applications.

Supramolecular Interactions as Key in Racemic Resolution: New Insights into the (SSi)‐ and (RSi)‐Diastereomers of (1R,2S,5R)‐Methyl(1‐naphthyl)‐phenylmenthoxy­silane of Sommer

A highly selective approach with high yields of two diastereomeric silicon‐stereogenic menthoxysilanes, (RSi)‐3 and (SSi)‐3, introduced by Sommer et al., could be established as well as investigated in detail using different analytical tools. Single‐crystal X‐ray diffraction analysis was used to examine the different crystallization rates while Hirshfeld surface analysis was applied to extend supramolecular interactions in the solid state which showed stronger hydrogen bridges for the faster crystallizing diastereomer (SSi)‐3. In addition, similar ground‐state energies have been found for both diastereomers by DFT calculations. Subsequent NMR studies showed stable Si‐configurations wherein epimerization only started after more than 4 hours at 110 °C. Access to both diastereomers with opposite configuration at the stereogenic silicon center is achievable in high yields and high stereochemical purity using only naturally occurring (–)‐menthol as a reagent.

Temporal and spatial resolution of magnetosome degradation at the subcellular level in a 3D lung carcinoma model

Magnetic nanoparticles offer many exciting possibilities in biomedicine, from cell imaging to cancer treatment. One of the currently researched nanoparticles are magnetosomes, magnetite nanoparticles of high chemical purity synthesized by magnetotactic bacteria. Despite their therapeutic potential, very little is known about their degradation in human cells, and even less so of their degradation within tumours. In an effort to explore the potential of magnetosomes for cancer treatment, we have explored their degradation process in a 3D human lung carcinoma model at the subcellular level and with nanometre scale resolution. We have used state of the art hard X-ray probes (nano-XANES and nano-XRF), which allow for identification of distinct iron phases in each region of the cell. Our results reveal the progression of magnetite oxidation to maghemite within magnetosomes, and the biosynthesis of magnetite and ferrihydrite by ferritin.Graphical

Uniform and large-size perovskite CsPb(BrxI1-x)3 quantum dot glass for laser display application

As a new display mode, laser display is becoming popular in the industry, and it has served our lives. In addition, a new material, perovskite quantum dots(QDs) is more capable of energizing laser displays with a narrow half-peak width, tunable emission and high color purity. Here, by incorporating perovskite CsPb(BrxI1-x)3 quantum dots into the glass, we explored the performance of large-size glass in laser display. It is demonstrated that the sheet of CsPbBr3 and CsPb(Br0.25I0.75)3 glasses has good wavelength uniformity, and the phosphor wheel with the sheets yields a wide color gamut (its color gamut reaches 124.3 % of NTSC and 91.3 % of Rec.2020), which will play a significant advantage in the field of laser projection.

A new approach for extracellular RNA recovery from Rhodovulum sulfidophilum

The development of RNA-based drugs is highly pursued due to the possibility of creating viable and effective therapies. However, their translation to clinical practice strongly depends on efficient technologies to produce substantial levels of these biomolecules, with high purity and high quality. RNAs are commonly produced by chemical or enzymatic methods, displaying these limitations. In this sense, recombinant production arises as a promising, cost-effective method, allowing large-scale production of RNA. Rhodovulum sulfidophilum (R. sulfidophilum), a marine purple bacterium, offers the advantage of RNA secretion into the extracellular medium, which contains low levels of RNases and other impurities. Therefore, RNA recovery can be simplified compared to standard extraction protocols involving cell lysis, resulting in a more clarified sample and an improved downstream process. In this work, R. sulfidophilum was transformed with a plasmid DNA encoding pre-miR-29b-1, which is known to be involved in the Alzheimer's disease pathway. After production, the pre-miR-29b-1 was recovered through different extraction methods to verify the most advantageous one. A protocol for extracellular RNA recovery was then established, revealing to be a simpler and less time-consuming method, reducing around 16 h in execution time and the quantity of reagents needed when compared to other established methods. The new strategy brings the additional advantage of eliminating the toxic organic compounds routinely used in intracellular RNA extractions. Overall, the optimized process described here, using isopropanol as the precipitation agent, offers a greener, safer, and faster alternative for recombinant RNA recovery and concentration, with an extracellular RNA recovery of 7 μg/mL and target pre-miRNA-29b-1 recovery of 0.7 μg/L of medium.

High purity H2 resource from methanol steam reforming at low-temperature by spinel CuGa2O4 catalyst for fuel cell

Methanol steam reforming (MSR) is an effective way to provide high purity hydrogen for PEMFCs, however the main challenge is the toxic effect of CO. In this study, CuGa2O4 spinel catalyst was applied first for MSR at low temperature. The properties of catalysts were characterized by various techniques, the MSR catalytic performance was also studied in deeply. The surface of the catalyst is composed of particle chains that are interconnected, forming high-volume pores that increase the specific surface area. The catalyst also has a rich porous structure, exposing more active sites. Furthermore, the presence of oxygen vacancies facilitates the adsorption of reactive oxygen species, reducing CO generation. A possible pathway for methanol dehydrogenation has been determined using DFT calculations. The relatively low overall energy barrier on the catalyst surface facilitates methanol activation. Among the steps, formaldehyde dehydrogenation is the rate-determining step in the methanol dehydrogenation process. The CuGa2O4 catalyst exhibits good gas selectivity, with a hydrogen selectivity of 98 % and CO selectivity of 0. and no deactivation occurred within 50 h, demonstrating outstanding durability. These features allow it to serve as an efficient catalyst for MSR online hydrogen production and direct supply to PEMFCs.

Effect of sintering temperature on magnetic, catalytic and photocatalytic properties of Cu-Co-Mn ferrite catalyst

Wastewater pollution is a pressing environmental issue, necessitating effective remediation strategies to mitigate its impact. This study investigates the use of an efficient catalyst for degrading nitrophenols by converting them into useful aromatic amines, which are crucial building blocks for many pharma industries, and photodegradation of various dyes in their unitary solution as well as in mixture. The Cu-Co-Mn ferrite was synthesized using the sol-gel process and sintered at different temperatures. Structural analysis using XRD and Rietveld refinement revealed a crystal structure corresponding to the Fd3‾m space group having high purity in all the samples. Additionally, the impact of sintering temperature on the magnetic features of the phases were also studied and the findings suggest that all the phases exhibit ferromagnetic behaviour, which means they can be easily separated from reaction mixtures using an external magnetic field. It was also found that higher sintering temperatures lead to a rise in saturation magnetization and magnetic moment with decrease in coercivity (Hc). Further, it was observed that Curie temperature (Tc) increases with increase in sintering temperature with the exception of CFM400. The catalytic performance of all the catalysts, including CFM400, CFM500, CFM600, CFM800, and CFM1000, was evaluated and the results indicate that CFM400 exhibits the highest catalytic activity for nitrophenols reduction and photodegradation of dyes, which could be accredited to its larger BET surface area and lower PL intensity. Overall, the structural and magnetic features of the catalyst’s sheds light on the underlying mechanisms governing their catalytic activity. These insights offer valuable guidance in the designing and development of effective catalysts for sustainable wastewater treatment practices, emphasizing the importance of considering both structural and magnetic features in catalyst design.

Foliar application of rice husk derived nanosilica for mitigating drought stress in hybrid maize by boosting antioxidant defense system

The increasing frequency and intensity of drought magnified by the climate change, pose significant challenge to global food security and agricultural productivity. Chemically synthesized nanosilica have emerged as a promising solution for managing drought stress, enhancing crop growth and stress resilience but, its production involves harmful chemicals which results in adverse impacts on soil, plant and environment. Hence, the present study aimed to green synthesize and characterize silicon nanoparticles from rice husk and to evaluate their potential for improving plant growth, development and stress mitigation in hybrid maize. The rice husk derived nanosilica has spherical morphology, amorphous nature, siloxane bonds and high purity (99%). Five different levels of nanosilica (0.05, 0.10, 0.15, 0.20 and 0.25%) were sprayed on hybrid maize grown under irrigated and drought conditions and the results revealed that, nanosilica spray has improved the stress tolerance, growth and photosynthetic parameters. An optimum response was noted with the nanosilica spray upto 0.10% in irrigated plants and 0.15% in drought stressed plants, where greater increase in plant height (27.7 and 28.9%), total biomass (55.7 and 39.1%), chlorophyll a (36.7 and 54.5%), relative water content (12.5 and 24.9%) and superoxide dismutase (23.0 and 35.7%) activity was observed. This was ascribed to the alleviation of membrane damage by reduced melondialdehyde content (18.9 and 21.4%) and electrolyte leakage (21.9 and 26.7%) under irrigated and drought regimes. However, higher doses of nanosilica caused slight reduction in plant growth and antioxidant activity. We conclude that, foliar spraying of nanosilica synthesized from rice husk at a concentration of 0.10% for irrigated and 0.15% for hybrid maize exposed to drought stress has shown a positive effect on plant growth and stress mitigation. Nanosilica synthesised from rice husk is economical, environmentally feasible and efficiently boosts plant growth and stress tolerance. Further, to confirm the role of rice husk derived nanosilica in plant stress tolerance, the comprehensive molecular mechanisms underpinning the stress mitigation has to be studied in detail.

A soft processing technology for the extraction of cellulose from plant residues and agri-food wastes

In this study, cellulose was extracted from giant cane (GC), Posidonia oceanica seagrass (PO), coffee silverskin (CS), and brewer’s spent grain (BSG) as alternatives to conventional sources of cellulose. The extraction protocol involved three steps: i) hemicellulose and lignin removal through alkaline hydrolysis in a 5% (w/v) NaOH solution (solid-to-liquid ratio = 1:100 g/mL, T = 25°C, t = 2h, ω = 300 rpm), ii) removal of organic compounds and ashes through a 95% (v/v) ethanol solution (solid-to-liquid ratio = 1:25 g/mL, T = 25°C, t = 0.5 h, ω = 500 rpm), and iii) double bleaching in a 1% (w/v) acidic (pH = 4) NaClO2 solution (solid-to-liquid ratio = 1:50 g/mL, T = 90°C, t = 1.5h, ω = 500 rpm). Yield, purity, crystallinity degree, and morphology of cellulose extracted through a soft-chemical cascade process were assessed by gravimetric, infrared (FT-IR), nuclear magnetic resonance (NMR) spectroscopy, X-ray diffraction (XRD), and scanning electron microscopy (SEM) analyses. Averaged cellulose extraction yields of 36.4, 38.6, 23.1, and 22.2% for GC, PO, CS, and BSG were obtained, respectively. All cellulose samples had high purity, though lower than the ultra-pure bacterial cellulose, which was due to the slight contamination from unremoved hemicellulose and lignin residues. Cellulose samples exhibited similar chemical features and the typical fibril-like morphology of microcrystalline cellulose (6 – 13 μm in width). The versatility of the proposed extraction procedure supports the sustainable conversion of low-cost organic biomasses to valuable products with manifold industrial applications (e.g., food packaging).

Homologous expression, purification, and characterization of a recombinant acetylxylan esterase from Aspergillus nidulans

Acetylxylan esterases (AXEs) are essential enzymes that break down the acetyl groups in acetylated xylan found in plant cell walls polysaccharides. They work synergistically with backbone-depolymerizing xylanolytic enzymes to accelerate the degradation of complex polysaccharides. In this study, we cloned the gene axeA, which encodes the acetylxylan esterase from Aspergillus nidulans FGSC A4 (AxeAN), into the pEXPYR expression vector and introduced it into the high protein-producing strain A. nidulans A773. The purified AxeAN, with a molecular weight of 33.5 kDa as confirmed by SDS-PAGE, was found to be active on ρ-nitrophenyl acetate (ρNPA), exhibiting a remarkably high specific activity (170 U mg−1) at pH 7.0 and 55 °C. AxeAN demonstrated stability over a wide pH range (5.5–9.0), retaining >80 % of its initial activity after 24 h. The KM and Vmax were 0.098 mmol L−1 and 320 U mg−1, respectively, using ρNPA as a substrate. We also evaluated the synergistic effect of AxeAN with an endo-1,4-β-xylanase from Malbranchea pulchella (MpXyn10) in the hydrolysis of four different xylans (Birchwood, Beechwood, Oat spelt, and Arabinoxylan) to produce xylooligosaccharides (XOS). The best results were obtained using Birchwood xylan as substrate and MpXyn10-AxeAN as biocatalysts after 24 h of reaction (50 °C), with an XOS-yield of 91 %, value 41 % higher when compared to MpXyn10 (XOS-yield of 63 %). These findings showed the potential of the application of AxeAN, together with other xylanases, to produce xylooligosaccharides with high purity and other products with high added value in the field of lignocellulosic biorefinery.

Synthesis and Development of a Nonaflate Ester in the Large-Scale Preparation of 3-Deoxymorphine

Abstract: A series of novel activated esters of morphine were synthesized as alternatives to the triflate ester and submitted to hydrogenolysis conditions. Of these, only the novel nonaflate ester could be transformed with full conversion into the useful intermediate, 3-deoxymorphine, which was isolated in good yield and high purity without chromatography. This conversion proceeded significantly faster than for the triflate ester and with synthesis of the intermediate nonaflate at much reduced cost, an important factor for the large-scale preparation of 3-deoxymorphine in drug development projects.

Synergistic action of novel maltohexaose-forming amylase and branching enzyme improves the enzymatic conversion of starch to specific maltooligosaccharide

As attractive functional ingredients, maltooligosaccharides (MOS) are typically prepared by controlled enzymatic hydrolysis of starch. However, the random attack mode of amylase often leads to discrete product distribution, thereby reducing yields and purities. In this study, a novel glycoside hydrolase family 13 amylase AmyEs from marine myxobacteria Enhygromyxa salina was identified efficient maltohexaose (G6)-forming ability (40 %, w/w). By deciphering external chain length, we found that the high density of α-1,6-branching points benefits the G6 formation of AmyEs with high purity (71–82 %), indicating the substrate selectivity of AmyEs toward high-branched starch. Based on this, asynchronous conversion strategy was designed to enhance specific MOS yield from corn starch by exploiting branching enzymes and AmyEs, and the purity and yield of G6 respectively increased by 9.5 % and 5 % compared to single AmyEs treatment. Our results demonstrate that combinatorial catalysis of MOS-forming amylases and branching enzymes provides a favorable industrial preparation of specific MOS.

Preparation and properties of Ta fiber reinforced high-entropy (Ti0.2Zr0.2Hf0.2Nb0.2Ta0.2)B2-SiC composite ceramics

High-entropy boride ceramics are expected to be widely used in aerospace, automotive turbines, and armor protection due to their advantages of high melting point, high hardness, adjustable performance, high-temperature stability, and good oxidation resistance. However, it is urgent to solve the problem of low fracture toughness before application. Therefore, in this paper, a single-phase high-purity (Ti0.2Zr0.2Hf0.2Nb0.2Ta0.2)B2 powder was prepared by boron/carbon thermal reduction method using a vacuum furnace. The effects of synthesis temperature and C content on the powder were studied. Secondly, HEB ((Ti0.2Zr0.2Hf0.2Nb0.2Ta0.2)B2) powder, SiC powder, and chopped Ta fiber were mixed uniformly, and Ta fiber toughened HEB-SiC composite ceramics were prepared by spark plasma sintering (SPS). The effects of Ta fiber content on the phase composition, microstructure, mechanical properties, and oxidation resistance of the composite ceramics were investigated. The results show that with the increase in synthesis temperature, the HEB powder gradually dissolves, and the solid solution is completely formed at 1700 °C. As the C content increases, the oxygen content and particle size of the powder gradually decrease. Single-phase high-entropy (Ti0.2Zr0.2Hf0.2Nb0.2Ta0.2)B2 powders with high purity were prepared at 1700 °C for 1 h with 6 wt% C content. The addition of C will promote the boron/carbon thermal reduction method, reduce the oxygen content, and inhibit grain growth. With the increase of Ta fiber content, the density of HEB-SiC-Taf composite ceramics increased first and then decreased. The hardness gradually decreased, and the fracture toughness gradually increased. When the Ta fiber content was 7 vol%, the fracture toughness was the highest, reaching 5.12 ± 0.39MPa⋅m1/2, which was nearly 45 % higher than that of the composite ceramics without Ta fiber. This is because of the synergistic toughening mechanism of metal toughening and fiber toughening, such as crack deflection, crack bridging, fiber debonding, and fiber pullout, which improves the fracture toughness of the composite ceramics. With the increase in oxidation temperature, B2O3, SiO2, Ta2O5, and various metal oxides appear on the surface of HEB-SiC-Taf composite ceramics. The oxidation depth and weight gain per unit area gradually increase. When the Ta fiber content is 5 vol%, the composite ceramics exhibit the best high temperature stability and oxidation resistance. This is due to the Ta2O5 formed by the oxidation of Ta fibers, which dissolves into the B2O3 glass phase, increasing viscosity and improving high temperature stability while reducing the oxygen diffusion rate.

Enhanced luminescence encryption via Mn4+ activation with organic acid surface modification

Mn4+-activated luminescent materials exhibit high color purity red light emission, but their limited water resistance hinders practical applications. In this study, citric and oxalic acids are innovatively employed for surface modification, resulting in luminescent materials with enhanced water resistance while preserving their luminescent intensity. This enhancement provides a prerequisite for their application in anti-counterfeiting films and aqueous fluorescent inks. Furthermore, the potential for optical information storage is successfully demonstrated by utilizing the photochromic fluorescent properties of polyvinyl alcohol films deposited on oxalic acid-modified K2SiF6:Mn4+. Exploiting the 3 ms day time difference between equivalently and non-equivalently doped Mn4+ fluoride, a millisecond information encryption mode is proposed by combining oxalic acid-modified K2SiF6:Mn4+ (long decay time, τ = 8.99 ms) and K3AlF6:Mn4+ (short decay time, τ = 5.31 ms). This mode can be effectively decoded using digital cameras and editing software, achieving high-level anti-counterfeiting capabilities. This work advances the application of highly efficient Mn4+-activated red phosphors in the realm of information security.

Design principles for >90% efficiency and >99% indistinguishability broadband quantum dot cavities

Abstract Quantum dots have the potential to be one of the brightest deterministic single photon sources with high end applications in quantum computing and cluster state generation. In this work, we re-examine the design of simple micropillars by meticulously examining the structural effects of the decay into leaky channels beyond an atom-like cavity estimation. We show that precise control of the side losses with the diameter and avoidance of propagating Bloch modes in the distributed Bragg reflectors can result in easy-to-manufacture broadband (Q≈ 750 − 2500) micropillars, allowing for broad optical coherent control pulses necessary for high single photon purity (> 99.2 − 99.99% achievable) while simultaneously demonstrating extremely high efficiency out the top (90.5% − 96.4%). We also demonstrate that such cavities naturally decouple from the phonon sideband, with the phonon sideband reducing by a factor of 5 − 33 allowing us to predict that the photons should show 98.5% − 99.8% indistinguishability without the need for filtering.