X-ray Diffraction Spectroscopy Research Articles

Recovery of Scandium from Bauxite Residue Using Sulfation Roasting-Assisted Water Leaching Process

ABSTRACT This study presents a method for recovering scandium from Indonesian bauxite residue (red mud) through a sulfation roasting-assisted water leaching process. Ammonium sulfate, (NH4)2SO4, was chosen as the sulfate source for its lower melting point, less corrosivity, decreased toxicity, and the potential for ammonia recovery. A modified mixing system was introduced to improve the distribution of (NH4)2SO4 on red mud particles by combining them in water. A series of experiments were conducted to optimize the sulfation roasting process by examining the effects of the (NH4)2SO4/red mud ratio, temperature, and roasting time. Subsequently, water leaching was optimized while considering the effect of leaching time and liquid-to-solid (L/S) ratio. The leaching of scandium from the roasted red mud showed rapid kinetics, even when using only water. Under the roasting conditions of 1/1 (g/g) (NH4)2SO4/red mud ratio, 700°C, 60 min roasting time, and the leaching conditions of 65°C, 60 min, and 10 mL/g (L/S), over 90% of scandium was recovered, along with 64.4% Al leaching and below 8% Fe leaching. These results were further corroborated through comprehensive analyses such as x-ray diffraction (XRD) and scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDS). This study offers insights into an alternative, more environmentally friendly method for Sc recovery from red mud, promoting the sustainable use of hazardous waste like red mud.

Synthesis and Catalytic Application of Cu2O Nano Hollow Arrays in RingExpansion Aromatization Reactions

Introduction: Aromatization of dithioacetal derivatives is essential for the synthesis of bioactive compounds and drug design, playing a key role in pharmaceuticals, agrochemicals, and materials science. This study explores the synthesis and catalytic application of Cu2O nano hollow arrays in ring-expansion aromatization reactions of cyclic dithioacetal derivatives obtained from cyclohexanones. Methods: By using Cu2O nano hollow arrays prepared through molecular templates and a simple hydrothermal process, the electrophilicity of N-bromosaccharin was enhanced, allowing for efficient and selective production of aromatic compounds with yields ranging from 63-96%. Copper acetate is transformed into Cu2O nano hollow arrays in aqueous media, with polyvinylpyrrolidone acting as a capping agent and (+)-L-tartaric acid as a structure-directing surfactant and multidentate ligand. Results: The synthesized Cu2O nano hollow arrays were characterized using transmission electron microscopy (TEM), field emission scanning electron microscopy (FESEM), energy-dispersive Xray spectroscopy (EDX), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS) to verify their morphology, structure, and composition. Conclusion: This method not only offers a cost-effective and environmentally friendly approach to synthesizing Cu2O with unique nano hollow structures, but also demonstrates their efficacy as catalysts in organic synthesis, particularly in the rarely reported ring-expansion aromatization of cyclic dithioacetal derivatives of cyclohexanone, emphasizing their broader applicability in materials science and catalysis.

Efficient Carbon-Based Optoelectronic Synapses for Dynamic Visual Recognition.

The human visual nervous system excels at recognizing and processing external stimuli, essential for various physiological functions. Biomimetic visual systems leverage biological synapse properties to improve memory encoding and perception. Optoelectronic devices mimicking these synapses can enhance wearable electronics, with layered heterojunction materials being ideal materials for optoelectronic synapses due to their tunable properties and biocompatibility. However, conventional synthesis methods are complex and environmentally harmful, leading to issues such as poor stability and low charge transfer efficiency. Therefore, it is imperative to develop a more efficient, convenient, and eco-friendly method for preparing layered heterojunction materials. Here, a one-step ultrasonic method is employed to mix fullerene (C60) with graphene oxide (GO), yielding a homogeneous layered heterojunction composite film via self-assembly. The biomimetic optoelectronic synapse based on this film achieves 97.3% accuracy in dynamic visual recognition tasks and exhibits capabilities such as synaptic plasticity. Experiments utilizing X-ray photoelectron spectroscopy (XPS), X-ray diffraction spectroscopy (XRD), Fourier-transform infrared spectroscopy (FTIR), ultraviolet-visible spectroscopy (UV-vis), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) confirms stable π-π interactions between GO and C60, facilitating electron transfer and prolonging carrier recombination times. The novel approach leveraging high-density π electron materials advances artificial intelligence and neuromorphic systems.

Corrosion behavior of Fe amorphous/Al-12Si piston composites with core-shell structure

The current piston material, Al-12Si, lacks sufficient passivation in the acidic lubrication system of biodiesel engines, making it prone to corrosion in the presence of Cl−. Fe amorphous particles exhibit good compatibility with Al-12Si, possessing strong corrosion resistance, excellent passivation ability, and good high-temperature stability. They are a potential reinforcement for enhancing the Al-12Si piston material. Fe amorphous/Al-12Si core-shell structural composites (FACS) were synthesized through ball milling and hot extrusion. The composites’ composition, microstructure, and elemental distribution were characterized by X-ray diffraction, optical microscopy, and EDS spectroscopy. To accelerate the evaluation process, Potentiodynamic polarization and Electrochemical impedance spectroscopy were used to study the electrochemical corrosion behavior. By analyzing the self-corrosion current density (icorr), self-corrosion potential (Ecorr), polarization resistance, inductance, admittance absolute value (Y0), and diffusion coefficient (n), the mechanism of Fe amorphous particle doping in enhancing the corrosion resistance of Al-12Si was discussed. The research results indicate that: The Fe amorphous particles, during ball milling and hot extrusion at 440 °C, do not recrystallize and maintain their good passivation ability. Spherical Fe amorphous particles act as “balls bearings” during hot extrusion, enhancing flowability and promoting the formation of a core-shell structure FACS with uniform composition distribution, high relative density, and low porosity when doping with 2–10% Fe amorphous particles. This prevents the formation of local potential differences, making the potential on the alloy surface more uniform, which helps reduce the risk of galvanic corrosion and improves corrosion resistance. However, when the doping content of Fe amorphous particles reaches 20%, excessive doping particles squeeze and rub against each other during hot extrusion, leading to amorphous agglomeration, low relative density, and high porosity defects in the resulting FACS, which causes uneven potential, increases local potential differences, and reduces corrosion resistance. Compared to Al-12Si, FACS doped with 2–10% Fe amorphous particles shows a decrease in icorr from 254.66 µA/cm2 to 114.98 µA/cm2, and an increase in Ecorr from 766.89 mV to 794.78 mV, indicating a reduced corrosion rate with the doping of an appropriate amount of Fe amorphous particles. As the doping content of Fe amorphous particles increases from 2 to 10%, the polarization resistance increases, indicating improved corrosion resistance; the inductance increases, suggesting that corrosion primarily occurs at the surface; Y0 increases, and n decreases, indicating a reduction in the depth of the corrosion reaction, and the stability of the surface protective oxide film is improved. However, when the doping content of Fe amorphous particles reaches 20%, the opposite effect occurs, and the corrosion resistance of the FACS decreases. Notably, FACS with 10% Fe amorphous particles exhibited the strongest corrosion resistance, making it a potential candidate for biodiesel engine pistons.

Thorium(IV) and Uranium(IV) Complexes with 2,6-Dipicolinoylbis(N,N-diethylthiourea) Ligands

The reaction of thorium nitrate hydrate with 2,6-dipicolinoylbis(N,N-diethylthiourea), H2Lpic, results in the hydrolysis of the organic ligand and the formation of [Th(2,6-dipicolinolate)2(H2O)4] (1). Hydrolysis can be avoided by the use of [ThCl4(DME)2] (DME = 1,2-dimethoxyethane) as the starting material and the exclusion of water. The product, [Th(Lpic)3]2− (2), crystallizes as diammonium salt in form of yellow crystals in moderate yields. The thorium ion in the complex is nine-coordinate by the central O,N,O donor atoms of three deprotonated {Lpic}2− ligands. The sulfur atoms of the ligands do not bind to the actinide ion, but establish hydrogen bonds to the ammonium counter ions. A similar coordination sphere is also observed in the uranium(IV) complex [UAu2(Lpic)3}] (3), which was obtained from a reaction between H2Lpic, [U2I6(1,4-dioxane)3] and [AuCl(tht)] (tht = tetrahydrothiophene) in the presence of triethylamine. Charge compensation is established by the linear coordination of two Au+ ions between each two sulfur atoms of the ligands. The products have been studied by X-ray diffraction and IR spectroscopy. The actinide ions in both {Lpic}2− complexes have coordination number nine, but establish slightly different coordination spheres.

Highly Green Fluorescent Carbon Dots from Gallic Acid: A Turn-On Sensor toward Pb2+ Ions.

Carbon dots (CDs) are emerging novel fluorescent sensing nanomaterials owing to their tunable optical properties, biocompatibility, and eco-friendliness. Herein, we report a facile one-pot hydrothermal route for the synthesis of highly green fluorescent CDs using gallic acid (GA) as a single carbon source in N,N-dimethylformamide (DMF) solvent, which serves as a nitrogen source and reaction medium. The optical properties of the synthesized GA-DMF CDs were systematically characterized by using UV-vis and photoluminescence spectroscopy, revealing strong green fluorescence. Further, to gain insights into their size and structural, elemental, and chemical composition, Fourier transform infrared, dynamic light scattering, high-resolution transmission electron microscopy (HR-TEM), X-ray diffraction, and X-ray photoelectron spectroscopy characterization techniques were performed. HR-TEM analysis confirmed the formation of uniformly spherical GA-DMF CDs with an average particle size of 16 ± 6.1 nm. Notably, the GA-DMF CDs exhibited a highly selective and turn-on fluorescent response to Pb2+ ions in aqueous solutions, which was attributed to a chelation-enhanced fluorescence mechanism. The detection limit for Pb2+ ions was determined to be as low as 7.15 × 10-7 M, with a broad linear detection range of 30-130 μM, underscoring their sensitivity and practical application in water quality monitoring. This study introduces a novel, sustainable approach for synthesizing nitrogen-doped CDs with outstanding optical properties and highlights their unprecedented selectivity toward Pb2+ ions, advancing the development of efficient and eco-friendly sensing platforms for heavy metal detection.

Effect of doping Mn ion on the crystal structure and cation distribution in Co1-xMnxFe2O4 compounds

In this study, we investigated the effect of Mn doping on the crystal structure and the distribution of cations at tetrahedral and octahedral sites in Co1-xMnxFe2O4 compounds (0 ≤ x ≤ 0.4), synthesized utilizing a solid phase reaction method, utilizing X-ray diffraction (XRD) and Raman spectroscopy measurements. The surface morphology and chemical composition of the compounds were studied using scanning electron microscope and X-ray energy dispersive spectroscopy. The Rietveld refinement of XRD data using the Fullprof package demonstrate that all studied samples are single phase spinels with no other detectable phases and have a cubic structure with the space group of Fd-3 m. The lattice constant and unit-cell volume increased with increased Mn doping concentration, which are attributed to the larger ionic radius of Mn in comparison with Co. Both the X-ray diffraction and Raman spectroscopy results demonstrated that doping Mn at the Co-site leads to the movement of Fe cations from the tetrahedral sites to the octahedral ones.

Hydrogel loaded with cerium-manganese nanoparticles and nerve growth factor enhances spinal cord injury repair by modulating immune microenvironment and promoting neuronal regeneration

BackgroundSpinal cord injury (SCI) treatment remains a formidable challenge, as current therapeutic approaches provide only marginal relief and fail to reverse the underlying tissue damage. This study aims to develop a novel composite material combining enzymatic nanoparticles and nerve growth factor (NGF) to modulate the immune microenvironment and enhance SCI repair.MethodsCeMn nanoparticles (NP) and CeMn NP-polyethylene glycol (PEG) nanozymes were synthesized via sol–gel reaction and DSPE-mPEG modification. Transmission Electron Microscopy, Selected-Area Electron Diffraction, X-ray Diffraction and X-ray Photoelectron Spectroscopy confirmed their crystalline structure, mixed-valence states, and redox properties. Size uniformity, biocompatibility, and catalytic activity were assessed via hydrodynamic diameter, zeta potential, and elemental analysis. The Lightgel/NGF/CeMn NP-PEG composite was synthesized and characterized via electron microscopy, compression testing, rheological analysis, NGF release kinetics, and 30-day degradation studies. Both in vitro and in vivo experiments were conducted to evaluate the therapeutic effects of the composite on SCI.ResultsThe Lightgel/NGF/CeMn NP-PEG composite was successfully synthesized, exhibiting favorable physical properties. At a CeMn NP-PEG concentration of 4 µg/mL, the composite maintained cell viability and demonstrated enhanced biological activity. It also showed superior mechanical properties and an effective NGF release profile. Notably, the composite significantly upregulated the expression of nerve growth-associated proteins, reduced inflammatory cytokines, scavenged reactive oxygen species (ROS), and promoted M2 macrophage polarization by inhibiting the cyclic GMP-AMP synthase (cGAS)-stimulator of interferon genes (STING) signaling pathway. In a rat SCI model, it facilitated functional recovery and attenuated inflammation.ConclusionThe Lightgel/NGF/CeMn NP-PEG composite shows significant therapeutic promise for SCI, effectively eliminating ROS, promoting M2 macrophage polarization, reducing pro-inflammatory cytokines, and supporting neuronal regeneration. These effects substantially enhance motor function in SCI rats, positioning it as a promising candidate for future clinical applications.Graphical

Raman Spectroscopy of Graphene/CNT Layers Deposited on Interdigit Sensors for Application in Gas Detection

Graphene/CNT layers were deposited onto platinum electrodes of an interdigitated sensor using radio-frequency magnetron sputtering. The graphene/CNTs were synthesized in an Argon atmosphere at a pressure of (2 × 10−2–5 × 10−3) mbar, with the substrate maintained at 300 °C either through continuous heating with an electronically controlled heater or by applying a −200 V bias using a direct current power supply throughout the deposition process. The study compares the surface morphology, carbon atom arrangement within the layer volumes, and electrical properties of the films as influenced by the different methods of substrate heating. X-ray diffraction and Raman spectroscopy confirmed the formation of CNTs within the graphene matrix. Additionally, scanning electron microscopy revealed that the carbon nanotubes are aligned and organized into cluster-like structure. The graphene/CNT layers produced at higher pressures present exponential I–V characteristics that ascertain the semiconducting character of the layers and their suitability for applications in gas sensing.

Sonochemical Functionalization of SiO2 Nanoparticles with Citric Acid and Monoethanolamine and Its Remarkable Effect on Antibacterial Activity.

Nanoparticles (NPs) are excellent antibacterial agents due to their ability to interact with microorganisms at the cellular level. However, their antimicrobial capacity can be limited by their tendency to agglomerate. Functionalizing NPs with suitable ligands improves their stability and dispersion in different media and enhances their antibacterial activity. The present work studied the functionalization of SiO2 NPs using the sonochemical method and the Influence of organic ligands on antimicrobial activity (AA). The organic ligands studied were citric acid (CA) and monoethanolamine (MEA). X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) results confirmed the amorphous structure of SiO2 NPs and their functionalization. Thermogravimetric analysis (TGA) and X-ray photoelectron spectroscopy (XPS) showed that functionalization with MEA (SiO2-MEA NPs) is more favored compared to AC (SiO2-CA NPs), and the organic ligand content was 34.42% and 28.0%, respectively. Fourier-transform infrared spectroscopy (FTIR) and RAMAN spectroscopy results confirmed the functionalization of NPs through the presence of carboxyl and amino groups. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), and zeta potential results showed that functionalization of SiO2 NPs helped to improve their dispersion and prevent their agglomeration. Furthermore, the results of antibacterial activity against Staphylococcus aureus and Escherichia coli showed that the functionalization provided a significant improvement in the antibacterial activity (AA) of the SiO2 NPs, where the SiO2-CA NPs showed the highest activity, with a 99.99% inhibition percentage at concentrations of 200 ppm against both E. coli and S. aureus strains. The AA is maintained at high concentrations of 1200 ppm, which is essential in applications requiring high percentages of biocidal NPs, such as marine coatings.

Investigation of the effect of Si content on the structural, mechanical, and tribological properties of TiAlN/AlSi protective multilayers

Abstract Titanium aluminum nitride and aluminum silicon alloys (TiAlN/AlSi) or for simplicity (TAN/AS) bilayer system were deposited on glass and piston aluminum substrates by following three steps. First, AlSi films realized by thermal evaporation with different Si content (7, 10, 13, 22) %. Then, TiAl films were deposited on AlSi layers using a reactive DC magnetron sputtering system, and finally the realization of TAN/AS multilayers were done by nitriding via Direct Current Plasma Nitriding (DCPN) in a custom setup, with pure nitrogen gas. For each sample, the structural properties like phase’s formation and vibration modes were investigated by X-ray diffraction and Raman spectroscopy, while AFM microscopy investigated surface topography. The mechanical and tribological properties in terms of hardness and friction coefficient were determined using the nanoindentation technique and tribometer. It has been found that all the coatings TAN/AS have crystalline structures with the presence of TiAlN, TiN, AlN, TiAl, and α-Al phases. Raman spectroscopy reveals the appearance of TO/LO, 2O, and 2TO/LO modes for all layers. AFM images show that the coatings have low roughness, Ra values decrease from 17.3 nm for 7 % Si to 5.5 nm for 13 % Si and increases to 9.9 nm at 22 % Si. The grain size exhibits a reversed behavior compared to that of roughness. The hardness and Young modulus reach their optimum values at 13 % Si with no respect to Hall–Petch law. The friction coefficient of TAN/AS coatings decreases with Si content and reaches its lowest value (<0.1) at 22 % Si as a potential protective layer.

Green Synthesis of Red Fluorescent Carbon Quantum Dots: Antioxidant, Hemolytic, Biocompatibility, and Photocatalytic Applications.

A straightforward one-step hydrothermal method is introduced for synthesizing highly efficient red fluorescence carbon dots (R-CQDs), utilizing Heena leaf (Lawsonia inermis) powder as the carbon precursor. The resulting R-CQDs exhibit excitation at 540nm and emission at 675nm, a high absolute photoluminescence (PL) with quantum yield of 40% in ethanol. Various physicochemical characterization was employed to confirm successful formation of R-CQDs including UV-Vis Spectroscopy, Fourier Transform Infrared (FT-IR) Spectroscopy, X-ray diffraction Spectroscopy, Transmission Electron Microscopy (TEM) and X-ray Photoelectron Spectroscopy. The optimization of synthesis parameters including synthesis method, effect of reaction temperature, effect of reaction time and effect of reaction concentration have a significant impact on the quality and quantity of synthesized R-CQDs, as well as their properties and applications. The effect of pH and UV radiation on synthesized R-CQDs exhibited excellent photo and chemical stability. Furthermore, R-CQDs had a high ability to protect cells from hydrogen peroxide-induced damage by scavenging hydroxyl radicals.In antioxidant activity, all three methods show approximately 80% of DPPH, Fenton's reaction and KMnO4 scavenging activity. In hemolytic assay shows no damage or destruction of red blood cells after exposure of R-CQDs. Cell viability and angiogenesis assays confirmed the biocompatibility of the R-CQDs, indicating that they might be useful as agents for cell labelling and useful for bioimaging probe. In dye degradation activity shows highest % of dye degradation in eosin and fluorescein with approximately 80% of dye degradation by using R-CQDs.

Characterization, Bioactive Profiling and Evaluation of the Pharmacological Activities of Ethanol Extract of Lannea welwitschii (Hiern) Engl.

Introduction: Lannea welwitschii is a medicinal plant used in traditional medicine to treat various infectious diseases due to its plethora of bioactive compounds that possess various pharmacological activities. This study aimed to characterize and determine the phytochemical profile and the bioactive compounds responsible for their pharmacological activities. Methods: Phytochemical screening and Gas-Chromatography Mass Spectrometry (GC-MS) analysis were carried out on the ethanolic extract of L. welwitschii to determine the volatile compounds present. Characterization of the crude extract was carried out using Fourier Transform Infrared spectroscopy (FTIR), Scanning Electron Microscopy (SEM), X-ray diffraction (XRD) and Energy Dispersive X-ray spectroscopy (EDX). The antioxidant potential of the extract was evaluated using methods such as 2,2-diphenyl-1-picrylhydrazyl (DPPH) and ferric-reducing antioxidant Potential (FRAP). The antibacterial activities were determined using the macro-broth dilution technique. Results: Secondary metabolites such as saponins, tannins, alkaloids, reducing sugars, and cardiac glycoside were identified. The GC-MS analysis showed the presence of 48 bioactive compounds, out of which 12 had peak area percentages ≥ 1%. Some of the bioactive compounds identified include 2-butoxy-ethanol, Dodecanoic acid, Stigmasterol, Isopropenyl, and n-hexadecanoic acid, which have been reported with different biological activities. FTIR analysis revealed the presence of various functional groups which showed major compounds in the plant extract. The morphological features showed the spherical shape of the plant extract with several aggregates, while the EDX analysis identified elements such as silicon, oxygen, and silver. The extract demonstrated inhibitory potential against some of the bacterial isolates. However, Bacillus pumilus, Klebsiella quasipneumoniae, Klebsiella aerogenes, and Staphylococcus aureus are more susceptible with MIC of 0.313 and 0.625 mg/ml respectively. Conclusion: The presence of secondary metabolites and bioactive compounds revealed by the characterization and phytochemical analysis provided enough evidence for the usage of the plant in the treatment of infectious diseases and thus might be considered a therapeutic agent.

Development of Novel Monolithic Catalyst for BTEX Catalytic Oxidation Using 3D Printing Technology

Four differently shaped monolithic catalyst supports were made using 3D printing technology. Two catalytically active mixed oxides, MnFeOx and MnCuOx, were applied to the monolithic supports using the impregnation technique. Catalysts were characterized using an adhesion test, field emission scanning electron microscopy, X-ray diffraction, and Raman spectroscopy in a manner similar to the density functional theory model. Excellent mechanical stability of the catalyst layer was obtained, with catalyst mass loss under 2% after 30 min of ultrasound exposure. SEM analysis revealed that the catalyst layer was rough but homogeneous in appearance and ~6 μm thick. The presence of double oxides—FeMnO3 and CuMn2O4—as well as single oxides of Mn, Fe, and Cu was established via XRD and Raman spectroscopy. Additional theoretical calculations of Raman spectra for FeMnO3 and CuMn2O4 were performed in order to aid in the interpretation of Raman spectra. The catalytic activity of the prepared catalysts for the catalytic oxidation of a gaseous mixture of benzene, toluene, ethylbenzene, and o-xylene (BTEX) was investigated. The monolithic support with the most complex shape and, consequently, the greatest surface area proved to enable the highest efficiency, while both catalysts performed well having similar conversions.

Microwave Plasma-Driven Synthesis of Graphene and N-Graphene at a Gram Scale

The large-scale microwave plasma synthesis of graphene and nitrogen-doped graphene with tailored structural properties, crucial for their successful usage applications, has been demonstrated. The developed atmospheric pressure plasma method offers several advantages, including the continuous production of high-quality, free-standing graphene without the use of chemicals, solvents, catalysts, or additional heating. This non-toxic process eliminates the need for vacuum systems while achieving high temperatures. The method enables the precise control over graphene’s properties, such as the layer number, defects, sheet size, uniformity, and functionality, as well as the doping type and configuration, by adjusting the plasma parameters. Protocols for the synthesis of specific nanostructures with a controlled structural quality, production rate, and chemical composition have been established using methane and methylamine as precursors. The comprehensive physicochemical characterization of the graphene and nitrogen-doped graphene was carried out using scanning electron microscopy, high-resolution transmission electron microscopy, Raman spectroscopy, X-ray diffraction, and X-ray photoelectron spectroscopy.

Optical tuning of polymer functionalized zinc oxide quantum dots as a selective probe for the detection of antibiotics

Excess consumption of antibiotics leads to antibiotic resistance that hinders the control and cure of microbial diseases. Therefore, it is crucial to monitor the antibiotic levels in the environment. In this proposed research work, an optical nano-sensor was devised that can sense the ultra-low concentration of antibiotics, in samples like tap water using fluorescent zinc oxide quantum dots (ZnO QDs) based nano-sensor. For this, different polymers (polyvinylalcohol–PVA and polyvinylpyrrolidine–PVP) capped florescent ZnO QDs were synthesized using a modified sol–gel technique. These were used as fluorescent probes to monitor the presence of antibiotics. The optical characterizations of synthesized QDs were performed using UV–visible absorption and fluorescence spectroscopic methods while structural characteristics were analyzed by using Raman spectroscopy and X-ray diffraction spectroscopy. The formation of capped QDs was confirmed by Fourier transform infrared spectroscopy (FTIR). Charge on the synthesized QDs was obtained with the help of ZETA potential. Here ten different antibiotics were checked, Ciprofloxacin and Moxifloxacin have shown excellent sensing and specificity with PVA-ZnO QDs and PVP-ZnO QDs with LOD of 1.4 nM and 0.8 nM, and sensitivity of 36.17 units/mM and 19.33 units/mM respectively. This study also inferred the tuning of the ZnO QDs properties and specificity towards the different antibiotics can be achieved by capping QDs with different polymers.

Engineering performance and environmental assessment of sustainable concrete incorporating nano silica and metakaolin as cementitious materials

The carbon footprint associated with cement production, coupled with depletion of natural resources and climate change, underscores the need for sustainable alternatives. This study explores the effect of metakaolin (MK) and nano-silica (NS) on concrete’s engineering performance and environmental impact. Initially, compressive, tensile, and flexural strength tests, along with durability assessments like water absorption, sorptivity, rapid chloride permeability, and resistance to acid and sulphate attacks, were conducted. Later, X-ray Diffraction spectroscopy and Field-emission scanning electron microscopy were employed for microstructural analysis. Subsequently, the environmental impact of micro and nano materials was assessed using embodied carbon emissions and eco-strength efficiency. The results revealed that the hybrid mixes of 12.50% MK and 2% NS (M7) showed superior performance, demonstrating significant strength enhancements and eco-efficiency, achieving 0.15 MPa/kg CO2/m3 at 28th day. Meanwhile, the MK-only mix (M6) yielded the lowest embodied CO2 emissions at 330 kg CO2/m3. MK and NS effectively reduce porosity and enhance durability against environmental factors while lowering clinker content, contributing to sustainability. Furthermore, the microstructural behaviour showed early hydration, dense microstructure and additional Calcium Silicate Hydrate formation, leading to improved properties. The outcomes reveal that the concrete configuration has altered at micro and nano levels by the inclusion of MK and NS, demonstrating their substantial contribution to producing environmentally friendly, effective, and beneficial concrete.

AuIII Acyclic (Amino)(N-Pyridinium)carbenoids: Synthesis via Addition of 2-PySeCl to AuI-Bound Isonitriles, Structures, and Cytotoxicity.

In this study, we report the first example of acyclic (amino)(N-pyridinium)carbenoid gold(III) complexes synthesized via a coupling reaction between 2-pyridylselenyl chloride and Au(I)-bound isonitriles. The reaction involves an initial oxidative addition of the Se-Cl moiety to Au(I), followed by the nucleophilic addition of the pyridine fragment to the isonitrile's C≡N bond, furnishing a metallacycle. Importantly, this is the first example of the pyridine acting as a nucleophile towards metal-bound isonitriles. Arguably, such an addition is due to the chelate effect. The structures of the gold(III) carbenoid complexes were unambiguously established using X-ray diffraction and NMR spectroscopy. Theoretical calculations, including DFT, Natural Resonance Theory (NRT), and Meyer bond order (MBO) analyses, were used to analyze the different resonance forms. The reaction mechanism was further elucidated using DFT calculations, which identified the oxidative addition as the rate-determining step with a barrier of 29.7 kcal/mol. The nucleophilic addition proceeds with a minimal barrier, making the reaction highly favorable. The antiproliferative activity of new compounds 2a-2e was tested against two human cancer cell lines: A2780 ovarian adenocarcinoma and the A278Cis cisplatin-resistant variant.

Solid-State Photoswitching of Hydrazones Based on Excited-State Intramolecular Proton Transfer.

The development of new photochromic systems is motivated by the possibility of controlling the properties and functions of materials with high spatial and temporal resolution in a reversible manner. While there are several classes of photoswitches operating in solution, the design of systems efficiently operating in the solid state remains highly challenging, mainly due to limitations related to confinement effects. Triaryl-hydrazones represent a relatively new subclass of bistable hydrazone photoswitches exhibiting efficient Z/E photochromism in solution. As "large volume" photoswitches, they have been anticipated to display only limited solid-state photoswitching. Here, we show that the Z isomers of newly prepared triaryl-hydrazones containing a perfluorinated hydrazine phenyl ring (PHZs) exhibit impressive solid-state photochromism with an unexpected light-induced red-shift of the absorption maximum. Based on (time-dependent) density functional theory calculations, a photoswitching reaction mechanism involving the excited state intramolecular proton transfer has been proposed, which rationalizes the observed red-shift in absorption by the formation of a metastable proton transfer structure. Advanced experimental techniques including X-ray diffraction, solid-state NMR and EPR spectroscopy, and confocal Raman microscopy corroborated the suggested mechanism and revealed that the observed photochromism is a superficial phenomenon. This atypical photochromic behavior of PHZs can also be realized by using visible light and in the form of thin films, which manifests their potential use in optics and optoelectronics.

Quantitative Estimation of Effective Brønsted Acid Sites of Silica-Supported H4SiW12O40 Heteropoly Acid for Adsorption of Various Molecules.

The amount of incorporation of linear alcohols and ethers in H4SiW12O40·6H2O (HSiW·6H2O, 50 wt %) supported on silica (SiO2) was estimated by a conventional volumetric method and infrared (IR) spectroscopy, and the state of involved molecules was elucidated. First, the attribution of the key IR band at 2200 cm-1, which was observed for the water of crystallization of HSiW·6H2O, to H5O2+ species (protons) was verified by coincident observation of thermogravimetric-differential thermal analysis, X-ray diffraction (XRD), and IR spectroscopy during thermal treatment in addition to the isotope exchange with D2O. The 2200 cm-1 band was gradually decreased in intensity by increasing the amount of adsorption of pyridine and was totally consumed at saturation, while the volumetric method provided the accurate number of included pyridine molecules. Thus, the decrease of the integrated intensity of the 2200 cm-1 band was employed to evaluate the extent of interaction of linear alcohols and ethers with H5O2+ species in equilibrium and irreversible conditions at room temperature. Linear alcohols (C1-C5) consumed almost all protons in equilibrium and about 50% in evacuation at room temperature, while about a half of protons were interacted in equilibrium and a quarter in evacuation in the case of dimethyl and diethyl ethers. Knowing the number of molecules incorporated and the amount of H5O2+ species consumed, the ratio of interacted molecules and H5O2+ species was estimated as H5O2+:molecules = 1:2-3. XRD patterns indicated the copresence of molecule-incorporated and molecule-free domains under irreversible conditions. Therefore, the incorporated molecules were concentrated around the H5O2+ species in HSiW·6H2O crystals. The state of absorbed molecules in HSiW·6H2O crystals was presumed by IR spectra: the presence of Fermi resonance of the hydrogen-bonded OH stretching band of H5O2+ species with CH deformation bands of interacted molecules implied the equilibrium state of as-interacted molecules and protonated species (transition state) at room temperature.