Major Absorption Bands Research Articles

Improved structural and dielectric traits of Cd-Zn spinel ferrites by co-substitution of La3+ and Er3+ cations

In the present work, the effect of co-doping of rare earth (Re3+), La and Er cations on the physical and dielectric performance of Cd-Zn spinel ferrites fabricated by sol-gel auto combustion method is reported. The prepared ferrites were doubly calcinated at 550 ℃ and 750 ℃ for 2 hours and 8 hours, respectively. The obtained samples were investigated using XRD, FTIR and dielectric measurements. XRD powder patterns verified the single-phase growth of spinel structure of all the as-synthesized ferrites with Fd-3m space group. The obtained results revealed that the Lattice constant reduces with increasing Er3+ concentrations, while crystallite size showed increasing behavior with increasing Er3+ concentration. FTIR results revealed the existence of two major absorptionbands i.e. low frequency bands in range 405-428 cm-1 and high frequency bands in range 523- 550 cm-1 which are evidence of spinel structure formation. LCR measurements are used to investigate the impact of co-doping of La3+ and Er3+ on the various dielectric parameters of prepared samples in response to frequency. Dielectric constant and loss decreased with the incorporation of Er3+, while an increase in ac conductivity was observed. The observed properties reveal that the prepared materials are suitable candidates for application in the high-speed microwave and radio frequency devices.

A series of triphenylamine-derived fluorophores attached to a Cu-based MOF for gaseous CO optical sensing: synthesis, performance, and mechanism.

A series of triphenylamine-derived fluorescent dyes were attached to a Cu2+-containing MOF (metal-organic framework), denoted as Pm@CuMOF. The molecular structures of these dyes were discussed by the single crystal structures. Their major absorption bands peaked at 410-450 nm, showing emission bands ranging from 556 to 586 nm with emission quantum yields ranging from 8.0 to 15.1%. It was found that the [-N(C2H5)2] group generally improved sensing performance, and the -OH group in the dyes helped the Cu2+ quenching effect. Pm@CuMOF was observed by SEM as nanorods with a width of ~100 nm and a length of 300 nm. Their XRD patterns and N2 adsorption/desorption isotherms were recorded to confirm their porous structure. A low probe loading level of ~4% was determined by TGA result. The CO sensing mechanism was revealed as a Cu2+/Cu+-involved sensing mechanism based on the result of NMR titration, IR, XPS, and EPR. The fluorescence of these triphenylamine-derived dyes was firstly quenched by CuMOF. In contact with CO, Cu2+ was reduced to Cu+, accompanied by the release and fluorescence recovery of the fluorescent dyes, showing emission turn-on effect towards CO gas. Pm@CuMOF showed increased emission intensity at CO level of 0.005% (versus N2), with response times ranging from 123 s to 280 s (depending on various temperatures). Good selectivity was observed over competing alkane gases, with stable emission for at least 5 days, but no linear calibration plots were observed.

Synthesis and characterization of zeolite Y from agricultural and municipal wastes: A waste management approach

Here in, we reported the utilization of guinea corn husk (an agricultural waste) and aluminium can (a municipal waste) for low-cost and sustainable means of zeolite Y preparation. Sodium silicate and sodium aluminate precursors were prepared from guinea corn husk and aluminium wastes respectively. The obtained solutions of the precursors were directly and hydrothermally converted to zeolite Y at 100 °C crystallization temperature for 24 h. The resulting zeolitic material was characterized by its properties. In comparison with collected standard data and commercially available zeolite Y, zeolite Y was successfully prepared from the waste resources. The result of X-ray Diffraction (XRD) indicated zeolite Y with good crystallinity, especially at the characteristic 2θ of 6.23°, 10.9° and 11.86°. The elemental compositions observed from Energy Dispersive X-ray (EDX) are in appropriate proportion and also confirmed the product. The Fourier Transform Infrared (FTIR) spectra showed the major characteristic absorption bands of zeolite in the mid-infrared region. It can be concluded that re-using agricultural and municipal wastes for the preparation of zeolite Y was achieved. This is a sustainable means of preparation of zeolite Y through a waste management approach for potential applications in adsorption, catalysis and ion exchange.

Chitosan-coated MIL-100(Fe) nanoparticles for enhanced piperine release in breast cancer treatment

Breast cancer is one of the leading causes of death among women with cancer worldwide. Piperine (PIP) is a promising compound with potential chemotherapeutic activity for the treatment of breast cancer due to its antitumor activity, but its toxicity has limited its introduction in preclinical studies. An attractive platform for the treatment of breast cancer is represented by PIP@MIL-100(Fe), a metal-organic framework (MOF) network encapsulated with PIP and used as a release system. An engineering strategy in nanotechnology is the surface modification of nanosystems, such as chitosan (CHI), which is used to increase resistance to degradation and enable controlled drug release. Based on these scientific and technological advances, the aim of this study is to evaluate the therapeutic potential of PIP encapsulated in metal-organic frameworks coated with CHI in the treatment of breast cancer. The CHI@PIP@MIL-100(Fe) was successfully synthesized, which consists of MIL-100(Fe) containing PIP and coated with CHI, using the impregnation method. The infrared spectroscopy analysis showed major absorption bands such as the saccharide structure (1042, 1092, and 1164cm−1), confirming the presence of CHI in the MOFs. The cytotoxicity tests conducted on breast cancer cells, including SKBR3, MCF-7, MDA-MB-231, and BT549, using CHI@PIP@MIL-100(Fe), exhibited lower cytotoxicity indices in comparison to free PIP, which showed an index that was three to four times higher. Therefore, these nanostructures show potential as PIP-based therapies for breast cancer.

Evaluation of antifungal efficacy of chitosan against Aspergillus fumigatus of stored rice (Oryza sativa)

Contamination of stored rice with fungal pathogens results in rice of poor quality and economic value, and may also have harmful effects on human and animal health. This study aimed at evaluating the antifungal efficacy of chitosan against Aspergillus fumigatus of stored rice (Oryza sativa). Four forms of chitosan were used in this study viz; Purchased Low, Medium and high molecular weight chitosan and chitosan synthesized from Crab Shell using deproteinization, demineralization, decolouration and deacetylation. Degree of deacetylation of the synthesized chitosan was determined using Fourier transform infrared (FTIR) analysis. The in vitro antifungal activity of all forms of chitosan were determined using food poisoning method against Aspergillus fumigatus isolated from stored rice seeds using agar plate methods. The percentage inhibition of mycelial radial growth Aspergillus fumigatus by the different forms of chitosan was determined. Fourier Transfrom InfraRed Spectra of synthesized chitosan showed major absorption bands from 3444.72, 2966.17, 2512.60, 2144.84, 1429.74, 1258.12, 1160.05, 1025.2, 869.92, 710.50, 608.40 to 559.36. Absorption peak at 559 was assigned to glucopyranose ring in the chitosan matrix. Degree of deacetylation of synthesized chitosan was at 98.6% degree. Highest mycelia radial growth of 8.00 cm was recorded in control, while 2.00, 0.00, 5.23, and 1.33cm were recorded in 2.0% concentration of High Molecular Weight Chitosan (HMWC), Medium Molecular Weight Chitosan (MMWC), Low Molecular Weight Chitosan (LMWC) and Chitosan synthesized from Crab shell (CSCS) treatment respectively. The result of the percentage inhibition reveals that A. fumigatus had 100% inhibition in 1.5% HMWC and 2.0% MMWC while 85% inhibition in 2.0% CSCS which were significantly different from 2.0% LMWC with 36.5% inhibitions. Results obtained from this study has shown the effectiveness of chitosan as an effective antifungal agent which can improve and maintain the quality of stored rice and ensure a safer environment due to its nontoxic and environmental friendly properties.

Detecting and characterizing the abundance and form of water-ice in permanently-shadowed regions of the moon using a three-band lidar system

We investigated the ability of a three-band lidar instrument (with wavelengths of 532, 1064, and 1560 nm) to detect and quantify different types of regolith ± water ice mixtures for both mare and highlands regions. A variety of samples were spectrally characterized, focusing on variables such as type of lunar regolith (simulant, lunar meteorite, highland vs mare), grain size (<45 μm, 45–1000 μm, <1 mm), water ice surface coverage and porosity of regolith (discontinuous, continuous, packed), and water ice percentages in intimate mixtures vs areal mixtures. Spectral metrics included absolute reflectance (532, 1064, 1560 nm) and reflectance ratios (1560/532, 1064/532, 1560/1064 nm). The ability to detect water ice in the presence of different types of regolith is critically dependent on the optical properties of end members, the selected wavelength, and the physical nature of the samples, such as grain size and areal vs intimate mixtures. Given the differences in the spectroscopic properties of the end members, both absolute reflectance and reflectance ratios have different predictive powers and both are required for robust analysis. The 1560 nm region is the most sensitive of the three wavelength regions to water ice content, as it falls well within a major water ice absorption band. Spectral contrast affects the ability to detect water ice. It is most sensitive for characterizing water ice + highland materials because the latter are brighter than water ice in this wavelength region. Powdered lunar materials are red-sloped across the 532 to 1064 to 1560 nm regions. By contrast, water ice shows a large downturn in reflectance between 1064 and 1560 nm. Detection limits for water ice in many situations can be as low as 2% and are lower for areal vs intimate mixtures. We found that porosity and angle of incidence with the surface have only minor effects on spectral reflectance properties of regolith. Further confirmation of water ice could be realized by comparing lidar data acquired by transects across permanently-shadowed regions and seeing how absolute reflectance and reflectance ratios vary between sunlit and adjacent shadowed regions. If it is known or assumed that regolith properties do not change as one enters a PSR, with the exception of the presence of surficial water ice, changes in reflectivity and reflectance ratios could provide compelling evidence for the presence of water ice.

Syntheses and properties of imidazolium-based quaternary salts with D-π-A unit containing azobenzene groups

Several novel organic ionic salts containing azophenyl groups with d-π-A structural unit was synthesized through the quaternization of azophenyl imidazole derivatives and 2, 4-dinitro-chlorobenzene in refluxing xylene. The donor-acceptor structure of the new ionic salts was characterized by the UV–vis, IR, ESI-MS, and NMR spectra. And the structure of ionic salt 8 was also evidenced by its single crystal X-ray diffusion. The UV−visible absorption spectra of all compounds exhibited two major strong absorption bands about at 340 and 440 nm, attributed to the strong intra-molecular π-π* and n-π* charge transfer of the azophenyl group, respectively. The results on thermal properties of ionic salts showed that all ionic salts 7–12 with d-π-A structural unit have better thermal stabilities and higher decomposition temperatures, and ionic salt 10 has the lowest melting point at 114 °C, almost close in the temperature range of ionic liquids. The electronic effect of substituted group has a certainly effect on the absorption spectra of azophenyl group and thermal properties of ionic salt with d-π-A structural unit.

A facile green approach to the synthesis of Bi2WO6@V2O5 heterostructure and their photocatalytic activity evaluation under visible light irradiation for RhB dye removal

Bismuth tungsten oxide and vanadium pentoxide (Bi2WO6/V2O5) heterostructures are produced by a green synthesis approach using Azadirachta indica extract for photocatalytic performance. The hydrothermal method at temperatures between 120 °C and 140 °Cis used to synthesize Bi2WO6. Bi2WO6 and V2O5 phases are formed in pure orthorhombic wells according to the XRD pattern. The SEM displays V2O5 nanorods, Bi2WO6 hierarchical microspheres that resemble flowers at 120 °C, and particles with a particle-like character at 140 °C. In V2O5, the asymmetric stretching vibrations of the triplely coordinated oxygen (chain oxygen) bonds and the vibration of the doubly coordinated oxygen (bridge oxygen) bonds are responsible for a peak at 611 cm−1. In FTIR spectra between 600 and 1600 cm−1, the major absorption bands in Bi2WO6 are attributed to the W-O stretching, Bi-O stretching, and W-O-W bridging stretching modes. Bi2WO6@V2O5 at 120 °C has the lowest bandgap energy (2.32 eV) and optical electronegativity (0.62), as well as the highest refractive index (2.57), extinction coefficient (2.21), and dielectric constant (εr = 0.72 and εi = 11.4) among all samples, making it a suitable material for photocatalysis. Rhodamine blue (RhB) dye degradation is used to measure the photocatalytic activity (PCA) of certain materials. The results showed that heterostructure V2O5@Bi2WO6 synthesized at 120 °C is more attractive among all samples due to high degradation of RhB dye under sunlight irradiation in 90 min.

Fabrication of novel BaO–Al2O3–Bi2O3–B2O3 glass system: Comprehensive study on elastic, mechanical and shielding properties

The influence of barium oxide to the elastic and shielding properties of alumina bismuth borate glass system with the compositions (BaO)x(Al2O3)0.05 (Bi2O3)0.3 (B2O3)0.65-x where x = 0, 0.05, 0.10, 0.15, 0.20, 0.25, 0.30 mol% and classified as G1, G2, G3, G4, G5, G6 and G7 were investigated. The elastic properties of the glass system were examined by bulk density, molar volume, X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy and non-destructive ultrasonic velocity measurement. The experimental results show that the density of the glass sample increase and molar volume of the glass sample was decrease. The XRD analysis revealed that the glass sample shows the characteristics of the amorphous nature without any sharp lines or peaks while the FTIR revealed the major broad absorption bands for borate glass structure. The ultrasonic velocities and elastic moduli measurement shows an increasing trend with the addition of BaO. The mass attenuation coefficient (MAC) demonstrated that the presence of BaO enhances the MAC values, resulting in an improvement in the shielding competency of the fabricated glasses. The highest interactions between photons and the atoms of the glasses occur around 0.122 MeV, and the glass samples have an excellent blocking capacity to photons, according to the effective atomic number (Zeff) data. Furthermore, the half value layer (HVL) revealed that when the BaO level in the composition increases, the HVL values will reduces. As a conclusion, the radiation shielding factors revealed that G7 glass with 30 mol% of BaO is the optimum performance of the produced samples.

Machine Learning-Assisted FTIR Analysis of Circulating Extracellular Vesicles for Cancer Liquid Biopsy.

Extracellular vesicles (EVs) are abundantly released into the systemic circulation, where they show remarkable stability and harbor molecular constituents that provide biochemical information about their cells of origin. Due to this characteristic, EVs are attracting increasing attention as a source of circulating biomarkers for cancer liquid biopsy and personalized medicine. Despite this potential, none of the discovered biomarkers has entered the clinical practice so far, and novel approaches for the label-free characterization of EVs are highly demanded. In this regard, Fourier Transform Infrared Spectroscopy (FTIR) has great potential as it provides a quick, reproducible, and informative biomolecular fingerprint of EVs. In this pilot study, we investigated, for the first time in the literature, the capability of FTIR spectroscopy to distinguish between EVs extracted from sera of cancer patients and controls based on their mid-IR spectral response. For this purpose, EV-enriched suspensions were obtained from the serum of patients diagnosed with Hepatocellular Carcinoma (HCC) of nonviral origin and noncancer subjects. Our data point out the presence of statistically significant differences in the integrated intensities of major mid-IR absorption bands, including the carbohydrate and nucleic acids band, the protein amide I and II bands, and the lipid CH stretching band. Additionally, we used Principal Component Analysis combined with Linear Discriminant Analysis (PCA-LDA) for the automated classification of spectral data according to the shape of specific mid-IR spectral signatures. The diagnostic performances of the proposed spectral biomarkers, alone and combined, were evaluated using multivariate logistic regression followed by a Receiving Operator Curve analysis, obtaining large Areas Under the Curve (AUC = 0.91, 95% CI 0.81–1.0). Very interestingly, our analyses suggest that the discussed spectral biomarkers can outperform the classification ability of two widely used circulating HCC markers measured on the same groups of subjects, namely alpha-fetoprotein (AFP), and protein induced by the absence of vitamin K or antagonist-II (PIVKA-II).

Comparative analysis of alkaline-extracted hemicelluloses from Beech, African rose and Agba woods using FTIR and HPLC

The vast application of hemicellulose in industry is greatly influenced by its chemical components. The current study focuses on identifying the chemical components of a high yield alkaline-extracted hemicellulose and characterization to serve as a guide for more specific and effective biotechnological uses. In this study we isolated hemicellulose from sawdust of three different wood species (Beech, African rose and Agba woods) and characterized them using FTIR and HPLC techniques. Hydroxyl spectra vibrations were observed at 3919-3671 cm−1 and 3454-3211 cm−1 which indicates the presence of non-hydrogen bonded OH stretch and normal polymeric OH stretch in all three samples. The samples contained residual lignin indicated by IR absorption bands at 1592 and 1525 cm−1. The presence of C=O stretching vibrations of acetyl groups at 1734 cm−1 indicated that African rosewood was generally an acetylated molecule. Each heteropolysaccharide also contained reducing monosaccharides at their ends suggested by the C–H stretching vibrations. Infrared absorptions characteristic of asymmetric β-1,6-glycosidic stretching was present in Beechwood and Agbawood, respectively, and African rosewood gave three absorption bands β-1,3-glycosidic stretch, β-1,4-glycosidic stretch and an asymmetric β 1,6-glycosidic stretch, respectively. Agbawood gave a major absorption band at 923.75 cm−1 corresponding to the absorption band at β-1,4-glycosidic stretching. African rosewood contained 96 % mannose and 4 % of an unidentified sugar. Beechwood contained primarily glucose, but Agbawood contained 20, 14, 8 and 57 % glucose, mannose, galactose, and an unidentified sugar, respectively.

Dry extrusion pretreatment of cassava starch aided by sugarcane bagasse for improved starch saccharification

The enzymatic hydrolysis of native starch lacks efficiency because starch is mostly confined in semi-crystalline granules. To address the challenges associated with gelatinization and render native cassava starch (CS) amenable to enzymatic hydrolysis (enzyme cocktail from Aspergillus awamori and Trichoderma reesei), dry-extrusion pretreatment of CS mixed with sugarcane bagasse (SB) was studied. Results showed that among the CS:SB mass ratios studied (1:1; 1:0.5 and 1:0.25), extruded CS:SB (1:0.25) gave the highest 3-hour glucose yield (71.5%) after enzymatic hydrolysis. Extrusion reduced CS:SB (1:0.25) crystallinity by 78% and increased the intensity of all major FTIR absorption bands by 67–202%. The optimum 3-hour glucose yield from extruded CS:SB (1:0.25) hydrolysis was 74.1%, which was 330% higher than from untreated CS. The water absorption and solubility indices of the treated biomass increased by 145% and 12,640%, respectively under the optimum conditions, aiding the hydrolysis process. The dry extrudates were easy to manipulate and store.

Impact of Co2+ on the spectral, optoelectrical, and dielectric properties of Mg0.25Ni0.25Cu0.5−xCoxFe1.97La0.03O4 ferrites prepared via sol–gel auto-combustion route

Spinel ferrites are attaining huge importance in the modern era, due to their incredible properties, which means they are widely used in various fields. Therefore, in this paper a cost-effective and environmentally friendly preparation of Mg0.25Ni0.25Cu0.5−xCoxFe1.97La0.03O4 (x = 0.0, 0.125, 0.25, 0.375, and 0.5) ferrites via the sol–gel auto-combustion method were carried out. How the structural and functional properties varied with the Cu to Co ratio was studied. It was found that the crystallite size (D) was reduced from 47.2 to 27.6 nm as the Co2+ increased from x = 0.0 to 0.5. While the two major absorption bands including the higher frequency band (υ1) and lower frequency band (υ2) lie in the range of 573.80–538.65 cm−1 and 470.37–405.65 cm−1 belong to the spinel matrix. Five active Raman modes were found in the range of wave number 200–800 cm−1 corresponds to the sublattices of the spinel structure. The optical bandgap increased from 0.85 eV to 1.33 eV for x = 0.0 to x = 0.25 and then observed optical band gap was 1.15 eV and 1.46 eV for x = 0.375 to x = 0.5. The resistivity (ρ) was minimum for Co2+ concentration x = 0.25 at low temperature, while at high temperature the resistivity (ρ) was maximum for Co2+ doping x = 0.25. The temperature coefficient of resistance percentage (TCR %) was −2.66%/K at 513 K for x = 0.25, as shown in the graphical abstract. At lower frequencies, the impedance was observed maximum for Co2+ doping x = 0.125 and minimum for x = 0.375. These findings indicate that the as-prepared ferrites are a potential candidate for optoelectrical and bolometric devices.

Studies on Structural Properties of Ytterbium (Yb3+) Substituted Mg–Cu–Zn Nano‐ferrites

AbstractNano‐ferrites with composition Mg0.55Cu0.05Zn0.4YbxFe2‐xO4 (where x = 0.0, 0.01, 0.02, and 0.03) are prepared by chemical method. The single‐phase cubic spinel structure ferrite formation is confirmed from X‐ray diffraction (XRD) analysis. The lattice constant and crystallite size of Mg–Cu–Zn ferrites found to be decreases with increasing concentration of Yb3+ content. The two major absorption bands appear in the range 432.16–441.55 cm–1 and 568.25–578.56 cm–1 corresponding to octahedral and tetrahedral sites in the Fourier transform infrared (FTIR) spectra suggest formation of ferrites. Morphological study shows the formation of nano‐ferrites. The EDX analysis approves the formation of required ferrites in desired stoichiometric ratio without any impurity phase.

Novel Immobilized Ligand on Polymer Matrix as Adsorbent for Water Purification

Abstract A novel polymer material that is capable of adsorption of Pb2+ and Cu2+ in aqueous solutions has been synthesized. 3-Aminopropyltriethoxysilane was reacted with tetraethylethoxysilane in methanol and aqueous solution of HCl to yield 3-aminopropypolysiloxane (APP). Reacting the APP with ethylchloroacetate in triethylamine yielded a functionalized 3-aminopropypolysiloxane (FAPP). The FAPP was reacted with urea to yield urea immobilized polysiloxane. FTIR spectra of the APP showed major absorption bands (cm−1) at: 1032.5-1042.7 (Si-O-Si), while the Urea-immobilized polysiloxanes (APPU) showed major absorption bands (cm−1) at: 3200 − 3400 υ(NH), 2929 − 2957 υ(C-H), 1505-1643 (C=O, C=C, C=N), and 1032.5-1042.7 (Si-O-Si). SEM-EDX analysis of APP and APPU showed mean pore volumes (nm3) of 113.49 ± 7.91 and 44.89 ± 7.44 respectively, and elemental composition (%) as follows: APP, O (36.68), Si (39.91); FAPP, O (29.43), Si (41.64), Cl (9.06); APPU, O (32.15), Si (28.42), N (25.42). APP maximum percentage adsorption of Pb2+ and Cu2+ in simulated water were 79.44 and 74.81 respectively, while APPU maximum percentage adsorption of Pb2+ and Cu2+ were in the range of 78.36 − 85.44 and 79.63 − 82.87 respectively. The maximum percentage adsorption of Pb2+ and Cu2+ which indicate the sorption capacities of the adsorbents occurred within the pH range of 8-10, contact time between 70-90 min, metal ion concentration of 20-25 ppm, dosage of adsorbent of 0.01 − 0.03 g for Pb2+ adsorption, and 0.04 − 0.05 g for Cu(II), and at a temperature of 90°C. The statistical analyses showed significant difference in the means of the effects of pH, time and concentration as F &amp;gt; Fcrit, except in the case of contact time for Cu2+. Temkin isotherm gave values of R2 in the range of 0.9210 − 0.9735 and best fitted the adsorption process. The urea immobilized polysiloxane (APPU) exhibited very high potential for adsorption of Pb2+ and Cu2+ in industrial effluent up to 100 %.

Rietveld Refinement and Study of Elastic Properties of Ni0.7Zn0.3DyxFe2-xO4 (0.0 ≤ x 0.03) Ferrite Nano-Structures

Dy substituted spinel ferrite nanoparticles of the composition Ni0.7Zn0.3DyxFe2-xO4 (x = 0.0, 0.015, 0.03) were fabricated by using sol-gel method. Structural and elastic properties of Ni-Zn ferrite were tailored by introducing the Dy3+ rare earth ions. Powder X-ray diffraction (XRD) and Infrared spectroscopy (IR) techniques were employed to investigate the phase purity, absorption bands, and elastic properties of the samples. The crystal structure and cell parameters were refined by using Rietveld refinement done by using Fulprof software. Rietveld refinement infers that the ceramics crystallized in single – phase cubic spinel structure having the space group Fd-3m. A slight increase in lattice parameter is observed due to substitution of Dy3+ ions in Ni-Zn crystal lattice. The vibrational study was achieved by using IR spectroscopy. Two major absorption bands (1 and 2) were observed in the frequency range of 350 to 800 cm-1 which confirms the co-existence of tetrahedral and octahedral sites of spinel structure. IR data was used to evaluate the elastic parameters like stiffness constant, young’s modulus, bulk modulus, rigidity modulus, poisons ratio, and Debye temperature. All the elastic moduli and Debye temperature are found increasing with increasing concentration of Dy3+ ions.

Can nano PZT-OPC composites be used as a smart γ-ray attenuator?

Nano PbZr0.52Ti0.48O3-ordinary Portland cement (PZT-OPC) composites were fabricated by a ball milling technique with different PZT content (30, 50, 70, and 90% by weight). The prepared samples were annealed at 600 °C. The structure, morphology, thermal and electrical properties of these annealed samples were investigated using X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and thermal gravimetric analysis (TGA). The effects of PZT on dielectric and piezoelectric properties of the composites were investigated. γ-ray spectroscopy was used to measure the γ-ray attenuation coefficients of the annealed nanocomposite samples using the 661.7 keV γ-ray of 137Cs source. The microstructure changes of the prepared composite samples were investigated using the positron annihilation lifetime (PAL) and Doppler broadening (DB) techniques. The XRD patterns show both PZT and cement peaks. Also, these patterns indicate the presence of PZT retards the hydration process of the Portland cement. The FTIR spectra show the major absorption bands for both PZT and cement. SEM images show the binding between calcium silicate hydrate and PZT which may be a better factor for improving the mechanical properties of the cement. TGA curves show a higher thermal weight loss for 50% PZT-OPC composite sample. The PZT-OPC composite sample with 50% PZT content shows the highest γ-ray mass attenuation coefficient compared with the other composite samples. The positron annihilation spectroscopy (PAS) results show that the size of large voids and the concentration of small defects increase by increasing PZT content. Also, these results reveal that the core electrons slightly reduced by increasing PZT content. The results indicate that the dielectric constant and piezoelectric coefficient values slightly and rapidly increase for composite samples with PZT content <50% and >50%, respectively. Finally, the 50% PZT-OPC composite sample showed novel shielding and acceptable piezoelectric properties to be used as a smart shield.

Rapid response in recovery time, humidity sensing behavior and magnetic properties of rare earth(Dy & Ho) doped Mn–Zn ceramics

In the present world, the development of room temperature humidity sensor materials has always been a very popular research field. Rare earth (RE) doped ferrites are considered as potential resistive humidity sensing material owing to its high remarkable surface morphology with high porosity. Recent studies have shown that ferrite ceramics have good response in recovery time and have excellent humidity sensing behavior. With this in mind, solution combustion synthesis was used to effectively prepare RE dysprosium (Dy3+) and holmium (Ho3+) doped Mn–Zn ferrite ceramics with the chemical formula Mn0·5Zn0.5DyxHoyFe2-xO4 (x = 0.005 to 0.03) (MZDHF) (where x, y = 0.0, 0.01, 0.015, 0.02, 0.025 and 0.03). The MZDHF XRD pattern revealed the purity of the samples without any secondary phase. The crystallite size MZDHF is in the nano range. Further, the calculated lattice parameter of MZDHF is found to be increasing with the RE content. The two prominent major absorption bands related to A-site and B-site were confirmed by FTIR spectra. The hysteresis loops of MZDHF are used to investigate the differences in magnetic properties with an Dy3+-Ho3+ concentration. The remanence magnetization, saturation magnetization, coercivity and anisotropy of the ferrites were determined. The saturation magnetization decreases with increase of Dy3+-Ho3+ concentration. The change in the surface resistance for all the samples was studied. Among all the samples, Mn0·5Zn0.5Dy0.03Ho0.03Fe1·96O4 composite has shown a drastic variation in resistance. And the corresponding sensing response for the same sample is found to be 99%. Along with this, the sample has shown a least hysteresis and good stability. Also, the Mn0·5Zn0.5Dy0.03Ho0.03Fe1·96O4 composite has shown a good timing behavior of 90 s and 18 s. The sensing mechanism for the prepared Mn0·5Zn0.5Dy0.03Ho0.03Fe1·96O4 composite was thoroughly discussed.

Synthesis, infra red characterization and antimicrobial evaluation of Schiff bases derived from 1, 3-diphenylprop-2-en-1-one and 1-phenyl-3-(4-chlorophenyl)-prop-2-en-1-one

Chalcones were synthesized via Claisen-Schmidt condensation between various substituted acetophenone and benzaldehyde using 20% cold alcoholic KOH as catalyst. Two Schiff bases were synthesized through the condensation reaction of the synthesized chalcones with 2,4-dinitrophenylhydrazine using concentrated H2SO4 as catalyst. The antimicrobial properties of the Schiff bases were determined using the standard disc diffusion method of anti-microbial sensitivity according to CLSI. The results of anti-microbial analysis were compared to ciprofloxacin and ampicillin as reference standards. The first Schiff base was N-(2,4-Dinitro-phenyl)-N'-(1,3-diphenyl-allylidene)-hydrazine (SB1), a hydrazone of 1,3-diphenylprop-2-en-1-one and the second was N-[3-(4-chloro-phenyl)-1-phenyl-allylidene]-N'-(2,4-dinitro-phenyl)-hydrazine (SB2), a hydrazone of 1-phenyl-3-(4-chlorophenyl)-prop-2-en-1-one. SB1 had a percentage yield of 97.57% and a decomposition temperature of 231-2340C while SB2 gave 98.74% as percentage yield and a melting point of 216-2180C. SB1 showed anti-microbial properties while SB2 showed no anti-microbial properties when both were tested against Staphylococcus aureus and Pseudomonas aeruginosa at a concentration of 10 mg/mL. SB1 had a diameter zone of inhibition of 4-6 mm for P. aeruginosa and 7-9 mm for S. aureus. SB1 was more effective against g positive than g negative bacteria at a concentration of 10 mg/L. The presence of the major absorption band in the range of 350-375 nm, attributable to the n-π* transition of aromatic ketones in the UV spectra of the synthesized chalcones gave credence to their proposed aromatic structure. The presence of strong bands at 1604 cm-1 for SB1 and 1601cm-1 for SB2 and the absence of carbonyl oxygen absorption band in their IR spectra gave credence to the formation of Schiff bases.

Synthesis and characterization of Al3+ substituted Ni–Cu–Zn nano ferrites

Ferro spinels with composition Ni0.2Cu0.2Zn0.6Fe2−xAlxO4 (x = 0.0 to 1.0 in steps of 0.2) were synthesized by co-precipitation method, in oxygen atmosphere, from corresponding analytical grade metal sulfates. Thermogravimetric (TG) analysis shows total mass loss around 30% up to 873 K temperature. X-ray diffraction studies confirm all composition with single-phase spinel, cubic structure with crystallite size 11–21 nm range. With increasing trivalent Al3+ content, lattice parameter ‘a’ decreases. Infrared spectra shown two major absorption bands, the lower frequency band ν2 observed in the range 433–463 cm−1, is assigned to octahedral site and higher frequency band ν1 observed in the range 565–593 cm−1, assigned tetrahedral site. The microstructures of the calcinated samples investigated by scanning electron microscopy and transmission electron microscopy indicate ferrite samples are porous in nature. The magnetic properties such as saturation magnetization and magneton number decrease with increasing Al3+ concentration.