Attenuated Total Reflection Infrared Spectroscopy Research Articles

Accelerated carbonation of hardened cement paste: Quantification of calcium carbonate via ATR infrared spectroscopy

AbstractIn context of carbon capture and storage in cement and concrete industry, there is a strong demand for fast, reliable, and low‐cost CO2 quantification methods. Attenuated total reflection infrared spectroscopy (ATR‐IR) in conjunction with multivariate calibration via partial‐least‐squares regression was applied to quantify CaCO3 in carbonated hardened Portland cement pastes, as this method shows great potential in the field of process control. Thermogravimetric analysis coupled with infrared spectrometry for the detection of the evolving gases was used as a reference for quantification. Three methods for the quantitative analysis with different partial‐least‐squares parameters were developed on a series of ground physical mixtures of slightly carbonated and highly carbonated hydrated cement pastes that had absorbed up to 77% of the theoretical capacity for CO2. Additional samples for optimization and validation of the method were prepared by accelerated carbonation of cylindrical slices of hardened cement paste as a function of exposure time. In these experiments, the major CO2 uptake occurs in the first 60 min until the formation of CaCO3 layers limits the diffusion of CO2 and Ca2+ ions. The developed partial‐least‐squares models provided low estimation errors of max. 1.5 wt% and high correlation coefficients above 99.5%. The validation covers a concentration range of 20–48 wt% of CaCO3. Limitations of the method are discussed.

Thermoelectric properties investigation of Tungsten carbide-filled poly (vinyl alcohol)/Polypyrrole ternary composites

ABSTRACT Many researchers have recently focused their attention on conductive polymer-based flexible thermoelectric (TE) materials. One of the most popular approaches for improving TE efficiency is the addition of inorganic components to conductive polymers. In this work, the TE properties of tungsten carbide-filled poly (vinyl alcohol)/polypyrrole (PVA/PPy/WC) ternary composites were examined for the first time. First, composites with varying WC weight ratios were produced by the solvent casting process. Scanning electron microscopy (SEM) investigations demonstrated the homogenous dispersion of WC particles in the composite structure, while X-ray diffraction (XRD) analyses determined the influence of WC addition on the crystal structure of the composite. The electrostatic interactions of each component were revealed by Fourier transform infrared-attenuated total reflectance spectroscopy (FTIR-ATR) and UV-vis studies. Additionally, with the addition of WC, the energy bandgap of PVA/PPy reduced from 5.71 eV up to 2.07 eV. From TE studies, it was obtained that the electrical conductivity of PVA/PPy increased from 3.35 × 10−3 up to 58 Sm−1 with the addition of 30% WC, while the power factor (PF) of PVA/PPy increased from 8,6 × 10−9 μWm−1K−2 up to 1.71 × 10−3 μWm−1K−2. Both composite samples had negative Seebeck coefficients, which are typical of n-type conductors.

Thermal Gradient Infrared Spectroscopy for Diffusion in Polymers.

Time-resolved Fourier transform infrared-attenuated total reflectance spectroscopy (FTIR-ATR) was used to measure diffusion in opaque and translucent samples. FTIR-ATR was used to measure the change in the absorbance near the heated ATR crystal surface. The infrared absorbance was then related to the concentration through the Beer-Lambert law. The sample used is a polymer electrolyte composed of lithium bis-trifluoromethanesulfonylimide (LiTFSI) salt in a block copolymer polystyrene-poly(ethylene oxide) (SEO). A new approach to introduce concentration gradients is presented using a temperature gradient that creates a small salt concentration gradient due to thermally driven mass diffusion (the Soret effect). This first method was compared to a second method that we reported using two laminated polymer electrolyte films of different salt concentrations. The thermal gradient study (method 1) covered three temperature differences of 10, 15, and 20 °C, while the second study (method 2) used three average molar ratios across isothermal temperatures ranging from 80 to 120 °C. The benefits and limitations of the new approach are reported, as is the activation energy for salt diffusion in this and similar SEO electrolytes. Developing new techniques to measure diffusion coefficients effectively will aid in the development of a variety of devices, including solid-state batteries and thermogalvanic cells, that are able to convert waste heat into electricity and improve the efficiency of power-generating systems. FTIR-ATR overcomes previous limitations in experimental techniques measuring diffusion coefficients. The results prove that thermal gradient FTIR-ATR is an effective and repeatable approach for determining Fickian diffusion coefficients in viscoelastic solids.

Creating Nature-Inspired Surface Roughness and Modifying Surface Chemistry of PVDF Electrospun Fibers Using Low-Pressure Plasma towards Omniphobic Membrane for Long-term Distillation

Today, water scarcity as one of the world's most pressing challenges, has caused many concerns. Seawater desalination based on membrane distillation (MD) has been introduced as an effective solution to deal with this problem. The surface of membranes used in MD is required to be modified to guarantee long-term performance via creating resistance against membrane wetting by low surface tension feeds. In this regard, beetle skin-inspired roughness was created on the surface of poly(vinylidene fluoride) (PVDF) electrospun fibers using low-pressure plasma technique. Synergistically, 1H, 1H, 2H, 2H-perfluorooctyl acrylate (PFOA) was polymerized on the fiber surface to modify its chemistry. In other words, using the plasma polymerization technique, the membrane surface energy was reduced thanks to (1) the increase in membrane surface roughness and (2) the change in the membrane surface chemistry, as confirmed by field-emission scanning electron microscope (FESEM) imaging, X-ray photoelectron spectroscopy (XPS) and Fourier-transform infrared-attenuated total reflectance (FTIR-ATR) spectroscopy. These changes led to an omniphobic membrane repelling water, engine oil and isopropanol with contact angles of 150°, 135°, and 119°, respectively. The long-term performance of the developed omniphobic membrane was demonstrated by conducting air gap membrane distillation (AGMD) for a duration as long as 600 min using a feed solution containing 3.5 wt% NaCl and 0.6 mM sodium dodecyl sulfate (SDS), which is ten times better than the performance of pristine membrane (60 min). Overall, the surface modification technique considered in this work yields an omniphobic membrane with stable long-term performance without compromising the membrane flux and salt rejection.

Silk Fibroin/Amino Acid Hybrid Organic Piezoelectric-Triboelectric Nanogenerator

Triboelectric nanogenerators (TENG) with great performance and biodegradability are desired for the expansion of novel medical devices and wearable electronics. The present study aims at the preparation of natural silk in the form of silk fibroin (SF) film for utilization in TENG and further improving its output efficiency by embedding organic-piezoelectric gamma-glycine (γ-gly) amino acid to be a hybrid-organic piezoelectric/triboelectric nanogenerator (HO-P/TENG). The attenuated total reflectance infrared spectroscopy (ATR-IR) results demonstrated the N-H, C = O, and C-N bonding for SF and SF/γ-gly, confirming its dominant effect with a strong electron-donating tendency from those amino groups. The scanning electron microscope (SEM) and synchrotron radiation X-ray tomographic microscopy (SR-XTM) images show good dispersibility of incorporated γ-gly on the surface and also inside the SF matrix relating to its content to improve the electrical performance homogeneously. By fabricating the device in the vertical contact-separation mode, the present SF/γ-gly HO-P/TENG at 15 wt% provides the maximum output voltage (VOC ) and current (ISC ) of 81 V and 121 μA with a maximum output power (Pmax ) of 205 μW at the external load resistance of 5 MΩ. This SF-based HO-P/TENG has the advantage of being cost-effective with simple fabrication, demonstrating great promise for practical uses.

Optimizing ciprofloxacin removal using ion exchange resin: Exploring operational parameters and assessing toxicity

The present study investigates the adsorption behavior of ciprofloxacin hydrochloride (CIP) onto the cationic resin Amberlite IR120. Equilibrium and kinetic experiments were conducted to assess the influence of resin mass (0.02 to 0.19 g), agitation rate (200 to 500 rpm), pH (2 to 11), and temperature (15 to 45 °C) on the efficiency of CIP removal. Non-linear models, coupled with error functions such as coefficient of determination (r2) and the sum of squared residuals (SQR), were employed to assess the compatibility between kinetic models (pseudo-first order, pseudo-second order, Elovich) and isotherm adsorption equations (Langmuir and Freundlich). The IR120 resin underwent characterization through scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDS), laser granulometry, nitrogen adsorption–desorption isotherms (BET), and attenuated total reflection infrared spectroscopy (ATR-FTIR). Utilizing the Langmuir model, the maximum adsorption capacity of CIP was determined to be 37 mg g−1. Based on the r2 values obtained from the kinetic models, the pseudo-first order and pseudo-second order models exhibited the best fit for all experimental data. Optimal conditions for the adsorption occurred at pH 7, temperature of 15 °C, resin mass of 0.08 g, and agitation rate at 300 rpm. Remarkably, complete elimination of toxicity towards Escherichia coli organisms was achieved, evidenced by the absence of antibacterial effects after 60 min of operation. Consequently, the results suggest that IR120 holds promising potential as an adsorbent for CIP removal.

Optimizing energy storage performance of ALD YSZ thin film devices via yttrium concentration variations

In the last decade, research has focused on fabricating new materials to accelerate the development of energy storage devices. In this work, metal-electrolyte-metal (Au-YSZ-Ru) structures were fabricated on silicon substrates using atomic layer deposition, sputtering, and thermal evaporation techniques. The effect of the yttrium concentration in YSZ films on their chemical, structural, optical, and electrical properties were studied. XPS analysis showed yttrium concentrations of 14.6, 10.3, 6.8, and 5.3 at.% for films with ALD cycle ratios Zr:Y of 2:1, 4:1, 6:1, and 8:1. Deconvolution of the oxygen XPS signal demonstrate the yttrium to oxygen vacancies ratio. The band gap was calculated through UV–vis indicating an increase in values with yttrium concentration. In addition, the trend was confirmed by reflection electron energy loss spectroscopy (REELS). The structure was investigated by performing X-ray diffraction (XRD) and infrared attenuated total reflectance spectroscopy (IR-ATR) measurements. Both results indicate a better crystallization of the cubic phase for the samples with lower concentrations, as the intensity of (111) diffraction peaks and IR band increased for lower yttrium concentrations. Impedance spectroscopy revealed an activation energy of 1.69, 1.32, and 1.28 eV for the 10.3, 6.8, and 5.3 at.% film concentration, respectively. According to cyclic voltammetry and charge-discharge tests, a lower yttrium concentration, 5.3 at.%, promotes electrode REDOX reactions improving the energy-storage properties.

Assessment of corrosion inhibition performance of olive leaf extract mediated chitosan–Ag nanocomposites and influence of KI addition for X60 steel in acid solution

Chitosan–silver (CHT–Ag) nanocomposite (NCP) containing various dosages of chitosan (0.5, 1.0 and 2.0 g) was synthesized in-situ using olive leaf extract (OLE) as reducing and capping agent. The OLE mediated CHT–Ag NCP was characterized using UV–vis spectrometer, attenuated total reflectance-infrared spectroscopy (ATR-IR), X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDS) and transmission electron microscopy (TEM) techniques. The prepared NCP was assessed as corrosion inhibitor for X60 steel in 5% HCl solution using weight loss (WL) and electrochemical (electrochemical impedance spectroscopy (EIS), linear polarization resistance (LPR) and potentiodynamic polarization (PDP)) methods complemented by surface analysis of the corroded carbon steel (CS) without and with the NCPs utilizing scanning electron microscopy (SEM)/EDS, 3D optical profilometer and atomic force microscopy (AFM). The influence of adding KI on the corrosion inhibition performance of NCPs was investigated as well. TEM results indicate that CHT–Ag nanocomposites are polydisperse and spherical in shape with sizes in the range of 3.7–18.1 nm. The crystalline nature of Ag nanoparticles in the nanocomposites was confirmed by XRD and TEM examination. The prepared NCPs function as effective inhibitors for X60 CS corrosion in the acidic environment. Corrosion inhibition effect was observed to increase with rise in the NCPs concentration with the optimum inhibition efficiency (IE) obtained at the maximum dosage of 0.5% studied. The order of corrosion inhibition performance followed the trend CHT2.0 – Ag > CHT1.0 – Ag > CHT0.5 – Ag NCP. Also, IE was found to decrease with rise in temperature. The PDP data indicates that the NCPs alone and in combination with KI, reduced X60 CS corrosion via the mechanism of active site blocking effect. The addition of KI to the NCPs improves IE but not due to synergism. The surface assessment data confirms the establishment of a protective layer due to NCPs adsorption on the X60 CS surface.

Rapid discrimination of Lentilactobacillus parabuchneri biofilms via in situ infrared spectroscopy

Microbial contamination in food industry is a source of foodborne illnesses and biofilm-related diseases. In particular, biogenic amines (BAs) accumulated in fermented foods via lactic acid bacterial activity exert toxic effects on human health. Among these, biofilms of histamine-producer Lentilactobacillus parabuchneri strains adherent at food processing equipment surfaces can cause food spoilage and poisoning. Understanding the chain of contamination is closely related to elucidating molecular mechanisms of biofilm formation. In the present study, an innovative approach using integrated chemical sensing technologies is demonstrated to fundamentally understand the temporal behavior of biofilms at the molecular level by combining mid-infrared (MIR) spectroscopy and fluorescence sensing strategies. Using these concepts, the biofilm forming capacity of six cheese-isolated L. parabuchneri strains (IPLA 11151, 11150, 11129, 11125, 11122 and 11117) was examined. The cut-off values for the biofilm production ability of each strain were quantified using crystal violet (CV) assays. Real-time infrared attenuated total reflection spectroscopy (IR-ATR) combined with fluorescence quenching oxygen sensing provides insight into distinct molecular mechanisms for each strain. IR spectra showed significant changes in characteristic bands of amides, lactate, nucleic acids, and extracellular polymeric substances (i.e., lipopolysaccharides, phospholipids, phosphodiester, peptidoglycan, etc.), which are major contributors to biofilm maturation involved in the initial adhesion processes. Chemometric methods including principal component analysis and partial least square-discriminant analysis facilitated the rapid determination and classification of cheese isolated L. parabuchneri strains unambiguously differentiating the IR signatures based on their ability to produce biofilm. All biofilms were morphologically characterized by confocal laser scanning microscopy on relevant industrial equipment surfaces. In summary, this innovative approach combining MIR spectroscopy with luminescence sensing enables real-time insight into the molecular composition and formation of L. parabuchneri biofilms.

Comparison of SVMR and PLSR for ATR-IR data treatment: Application to AQC of mAbs in clinical solutions

Attenuated Total Reflectance Infrared spectroscopy (ATR-IR) enables rapid, preparation-free and cost-effective analysis of many clinically relevant samples. For instance, it can substitute traditional techniques like high performance liquid chromatography (HPLC) for Analytical Quality Control (AQC) of therapeutic solutions of anticancer drugs like monoclonal antibodies (mAbs). More reliable quantitative interpretation of the ATR-IR spectra is usually achieved with multivariate data mining protocols. In the present study, the analytical performance of ATR-IR was evaluated for four clinical solutions of mAbs: Bevacizumab (Avastin®), Trastuzumab (Ontruzant®), Cetuximab (Erbitux®) and Rituximab (Truxima®). As expected, the ATR-IR spectra were a combination of the bands of the antibody itself and those of the excipients. For quantitative analysis of the solutions, two types of regression methods have been compared namely, Partial Least Squares Regression (PLSR) and Support Vector Machine Regression (SVMR). While both approaches were relevant, the latter gave better performances in terms of accuracy, linearity and the percent relative error that was below 15%. The results are thus promising for future applications of ATR-IR Spectroscopy coupled to the SVMR algorithm as a clinical tool for AQC of mAbs.

Effect of Incorporation of Graphene Nanoplatelets on Physicochemical, Thermal, Rheological, and Mechanical Properties of Biobased and Biodegradable Blends.

This work aimed to study the effect of the incorporation of graphene nanoplatelets (GRA 0.5% and 1% (w/w)) on the matrices of biobased polymers composed of starch-based materials (B20) and poly(butylene succinate) (PBS) using pine rosin (RES) as a compatibilizer. Three formulations were produced (B20/RES/PBS, B20/RES/PBS/GRA0.5%, and B20/RES/PBS/GRA1%), and their mechanical properties (tensile, flexural, hardness, and impact), rheological behavior, thermal properties (thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC)), chemical analysis (Fourier transform infrared-attenuated total reflectance (FTIR-ATR) spectroscopy), and contact angle were evaluated. Hardness (Shore D), tensile, and flexural moduli increased, whereas elongation at break and toughness decreased as GRA content increased. FTIR studies strongly supported the existence of interactions between polymeric matrices and the large surface area of GRA. The viscosity flow curves were well fitted to the Cross-Williams-Landel-Ferry (Cross-WLF) model, and the three formulations exhibited non-Newtonian (shear-thinning) behavior. The analysis of water contact angles indicated that the formulation surfaces have hydrophilic behavior. All the samples are thermally stable, and the results of this study can be used to optimize the application of biobased graphene-based composites for applications in injection molding industries.

Electrochemical Ethylamine Dehydrogenation to Acetonitrile on Platinum-Based Catalysts

Hydrogen storage is a crucial link between green hydrogen generation by water electrolysis and hydrogen application in fuel cells. We very recently reported a new, electrochemical ethylamine/acetonitrile redox method for hydrogen storage [1]. This method realizes hydrogen uptake by pairing acetonitrile hydrogenation to ethylamine reaction (AHR) on cathode and hydrogen oxidation reaction (HOR) on anode, and realizes hydrogen release by pairing ethylamine dehydrogenation to acetonitrile reaction (EDR) on anode and hydrogen evolution reaction (HER) on cathode. With 8.9 wt.% theoretical storage capacity and ambient reaction conditions being demonstrated in the study, this method shows a great potential to advance hydrogen storage technology and meet the DOE target. One remaining challenge of this method was a rapid activity decay of the used commercial platinum catalyst (Pt/C) in the EDR, which caused a long-term durability issue.In this work, we report our fundamental study of Pt catalyst deactivation mechanism in EDR and the discovery of new Pt-based catalysts. Attenuated total reflection infrared spectroscopy (ATR-IR) was employed for characterizing working catalyst surface under reactive conditions. Partially dehydrogenated intermediate species were observed to generate on Pt surface, which strongly adsorbed and caused an accumulation and blockage of the active sites. Interestingly, the catalyst showed a self-cleaning property where the intermediates can be hydrogenated back to ethylamine and released from Pt surface below 0 V vs. RHE. A group of Pt-Ni alloy catalysts were prepared and investigated the composition effect in this reaction, among which Pt3Ni exhibited 75% higher activity and significantly improved stability compared to Pt. ATR-IR experiments showed that the accumulation of intermediates on the Pt3Ni surface was much slower than that on the Pt, attributed to weakened adsorption. This work provides mechanistic insights into EDR reaction pathways and the cause of Pt catalyst deactivation and offers a Pt alloy strategy for active and stable catalyst design.[1] Wu, D.; Li, J.; Yao, L.; Xie, R.; Peng, Z. ACS Appl. Mater. Interfaces 13, 55292 (2021).

Production of Hydrogels from Microwave-Assisted Hydrothermal Fractionation of Blackcurrant Pomace.

The exploitation of unavoidable food supply chain wastes resulting from primary and secondary processing for chemicals, materials, and bioenergy is an important concept in the drive towards circular-based, resource-efficient biorefineries rather than petroleum refineries. The potential production of hydrogels (materials) from unavoidable food supply chain wastes, which are naturally rich in biopolymers such as cellulose, hemicellulose, pectin, and lignin, represents an interesting opportunity. However, these intertwined and interconnected biopolymers require separation and deconstruction prior to any useful application. Thus, this study aims to explore the formation of hydrogels from defibrillated celluloses (MW-DFCs) produced via acid-free stepwise microwave hydrothermal processing of blackcurrant pomace residues. Initially, pectin was removed from blackcurrant pomace residues (MW, 100-160 °C), and the resultant depectinated residues were reprocessed at 160 °C. The pectin yield increased from 2.36 wt.% (MW, 100 °C) to 3.07 wt.% (MW, 140 °C) and then decreased to 2.05 wt.% (MW, 160 °C). The isolated pectins were characterized by attenuated total reflectance infrared spectroscopy (ATR-IR), thermogravimetric analysis (TGA), and 13C NMR (D2O). The cellulosic-rich residues were reprocessed (MW, 160 °C) and further characterized by ATR-IR, TGA, and Klason lignin analysis. All the MW-DFCs contained significant lignin content, which prevented hydrogel formation. However, subsequent bleaching (H2O2/OH-) afforded off-white samples with improved gelling ability at the concentration of 5% w/v. Confocal laser microscopy (CLSM) revealed the removal of lignin and a more pronounced cellulosic-rich material. In conclusion, the microwave-assisted defibrillation of blackcurrant pomace, an exploitable unavoidable food supply chain waste, affords cellulosic-rich materials with the propensity to form hydrogels which may serve useful applications when put back into food products, pharmaceuticals, cosmetics, and home and personal care products.

Inspired dual functional adsorption films of armed molecules on copper

AbstractIn this study, double norfloxacin skeletons including the target armed molecules (DNs) displaying antibacterial and anticorrosion properties for copper in aqueous solutions were presented. The molecular modelling and material simulation calculations suggest that the target molecules could be adsorbed to copper surface, which was further demonstrated by attenuated total reflection infrared spectroscopy (ATR‐IR), X‐ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), and scanning electron microscopy (SEM). The experimental results show that the copper surface which adsorbed the target armed molecules exhibited an excellent inhibitory effect on Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). The potentiodynamic polarization plots and electrochemical impedance spectroscopy demonstrate that the DNs of 0.100 mM achieved over 95% corrosion inhibition efficiency for copper in 0.5 M H2SO4 solution at 298 K. The results given in this study may guide us to achieve bacterial and corrosion resistances for copper based on the drug‐included armed molecules.

Influence of direct fluorination treatment on surface and optical properties of colorless and transparent polyimides

Due to excellent comprehensive performance, colorless and transparent polyimide (CPI) films are the greatest potential substrates for flexible displays, lighting, and solar cells. In this work, CPI films were modified by direct fluorination to increase the wettability and transmittance. The effects of fluorination duration on the chemical structure and surface physical morphology of CPI films were investigated in detail by attenuated total reflection infrared spectroscopy (ATR-FTIR), X-ray photoelectron spectroscopy (XPS), and scanning electron microscopy (SEM). The results show that, depending on the fluorination duration, direct fluorination causes significant changes in surface composition and structure. The F/C and O/C ratios of the samples were enhanced as the fluorination time increased. Surface microcrack increased at initially, then decreased as fluorination time increased. The fluorinated surfaces exhibit a high hydrophily and lipophobicity, and consequently a very high surface energy, according to contact angle measurements. In comparison to original CPI film, the fluorinated CPI films exhibited higher optical transmittance in the ultraviolet–visible light region compared with original CPI film. In addition, the fluorinated CPI films showed good thermal stability up to 500 °C and higher glass transition temperatures (Tg) compared with original CPI film.

Interfacial shear strength of surface functionalized and functionalized CNT coated carbon fiber: A single fiber fragmentation study

The compatibility among nonpolar thermoplastics like polypropylene (PP) and carbon fibers (CF) having traditional sizing or coating is challenging. In this study, facile and effective surface functionalization of CF and its subsequent coating with functionalized carbon nanotubes (CNTs) were carried out to obtain improved interfacial shear strength (IFSS) which was validated by the single fiber fragmentation test (SFFT). Functional groups, -COOH, -OH, and -NH2, were separately grafted on the CF surface using different chemical routes. Additionally, ultrasonic assisted electrophoretic deposition (EPD) technique was used to coat -COOH, -OH, and -NH2 functionalized CNTs on the sized and surface functionalized CFs. Attenuated total reflection-infrared spectroscopy (ATR-IR), X-ray photoelectron spectroscopy (XPS), and field emission scanning electron microscopy (FE-SEM) images confirmed the successful surface functionalization and coating on CF. Neat PP and a blend of PP and maleic anhydride-grafted-styrene ethylene butylene styrene (MA-g-SEBS) were used as two different base polymer matrixes in preparing a total of 26 different SFFT samples. Silane functionalized CF coated with amine functionalized CNTs using ultrasonic assisted EPD process showed IFSS of ∼29 MPa which was an impressive ∼758% higher than pristine CF and highest among all the surface modified CFs. Interestingly, this translated into useful increase of ∼13% in single fiber tensile strength of functionalized and treated CF over and above that of as received CF.

Creation of surface frustrated Lewis pairs on high-entropy spinel nanocrystals that boosts catalytic transfer hydrogenation reaction

Creating frustrated Lewis pairs (FLPs) on stable high-entropy oxides (HEOs) is a new challenge, and also an uncultivated field in catalysis. Herein, holey layered HEO spinel nanocrystals with rich FLPs were synthesized via a temperature-driven topological transition. The FLPs on the surface of HEO spinel nanocrystals are created by oxygen vacancies (Lewis acid sites) and proximal surface hydroxyls or surface lattice oxygen (Lewis base sites). Rich FLPs furnish HEO nanocrystals a superior activity towards the catalytic transfer hydrogenation reaction of biomass-derived carbonyl compounds at mild conditions. The active regions in between FLPs provide a strong driving force for dissociating alcohols and activating carbonyl groups of substrates, as evidenced by the attenuated total reflectance-infrared spectroscopy (ATR-IR) analysis, which enhances the catalytic activity. This work develops a new kind of hydrogenation catalysts and provides a perspective for creating solid FLPs.

Green synthesis of silver nanoparticles via Aloe barbadensis miller leaves: Anticancer, antioxidative, antimicrobial and photocatalytic properties

Current work reports biogenic synthesis and physico-chemical characterization of silver nanoparticles (AgNPs) by using Aloe barbadensis miller leaves extract (ALE). The prepared biogenic AgNPs have been characterized physico-chemically by X-ray powder diffraction (XRD), UV-visible spectrometry, attenuated total reflectance infrared spectroscopy (ATR-IR), Atomic force microscopy (AFM) and Field emission- scanning electron microscopy (FE-SEM). The characteristic highest absorption peak at 439 nm confirmed the synthesis of AgNPs. Further, the biomedical and catalytic potential of AgNPs was investigated by their anticancer, antioxidative, antimicrobial, and photocatalytic properties. The anticancer potential of AgNPs was evaluated against the breast cancer (MCF-7) cells using MTT cytotoxicity assay. AgNPs proved to be anticancer even for the minimum concentrations of 10 µg/ml, and the anticancer efficiency was increased with increase in concentration. AgNPs showed 42.51% free radical scavenging activity due to their antioxidative nature. 0.3 M AgNPs showed maximum antimicrobial activity with 20 mm zone of inhibition against E. coli bacteria. Additionally, the AgNPs were tested for photocatalytic dye degradation of eosin, crystal violet, carbol fuchsin, methylene blue, and saffranine dyes with maximum % degradation 70.76%, 95.54%, 94.63%, 93.53%, and 90.12%, respectively. The study is unique as the biosynthesized silver nanoparticles by using Aloe barbadensis miller leaves extract shows promising anticancer, antioxidative, antimicrobial, and photocatalytic properties. Herein, the present study reveals the potential of biosynthesized AgNPs for improved therapeutic and catalytic applications.

Synergetic effect of Fe/Ag ions incorporated HAp on AZ31 Mg alloy to improve corrosion resistance and osteogenic activity

In clinical applications, the rapid deterioration of biodegradable magnesium alloys under in-vitro and in-vivo conditions is a key problem. However, to overcome the limitations surface modification treatments on this material are performed. In this work, a Fe/Ag-HAp coating was developed for biodegradable AZ31 Mg alloy to enhance the corrosion resistance and osteoconductive of the material. The surface morphological studies displayed a flaky-like aggregated structure. In addition to validating the functional groups with Attenuated Total Reflectance Infrared (ATR-IR) spectroscopy and X-Ray Diffraction (XRD) were used to analyze the crystal structure of the samples. Moreover, real-time corrosion was monitored by hydrogen evolution, indicating 2.8 ml of gas was evolved in the coated sample compared with bare material. The potentiodynamic polarization and electrochemical impedance studies revealed the significant corrosion rate and strong impedance resistance of the coating materials. After 7 days of immersion in SBF solution, the coating recruited calcium/phosphate from the entire sample, as observed in the cauliflower-like structure, and the functional group was confirmed by ATR-IR spectroscopy. MTT was performed using MG-63 osteoblast-like cells, the samples were incubated for 24 h and revealed better adhesion on the surface which was observed by SEM. Osteogenic differentiation was evaluated in 3 and 5 days and it showed a significant increase in cell proliferation rate.

Preparation and Properties of (Sc2O3-MgO)/Pcl/Pvp Electrospun Nanofiber Membranes for the Inhibition of Escherichia coli Infections.

Due to their high porosity, large specific surface area, and structural similarity with the extracellular matrix (ECM), electrospun nanofiber membranes are often endowed with the antibacterial properties for biomedical applications. The purpose of this study was to synthesize nano-structured Sc2O3-MgO by doping Sc3+, calcining at 600 °C, and then loading it onto the PCL/PVP substrates with electrospinning technology with the aim of developing new efficient antibacterial nanofiber membranes for tissue engineering. A scanning electron microscope (SEM) and energy dispersive X-ray spectrometer (EDS) were used to study the morphology of all formulations and analyze the types and contents of the elements, and an X-ray diffraction (XRD), thermogravimetric analysis (TGA), and Fourier transform attenuated total reflection infrared spectroscopy (ATR-FTIR) were used for further analysis. The experimental results showed that the PCL/PVP (SMCV-2.0) nanofibers loaded with 2.0 wt% Sc2O3-MgO were smooth and homogeneous with an average diameter of 252.6 nm; the antibacterial test indicated that a low load concentration of 2.0 wt% Sc2O3-MgO in PCL/PVP (SMCV-2.0) showed a 100% antibacterial rate against Escherichia coli (E. coli).