Strong Absorption Bands Research Articles

Thermal potential porous materials and challenges of improving solar still using TiO2/Jackfruit peel - enhanced energy storage material

In this work, the first introduced substitute blends were functional, and active heat transfer increased with the below act on the new distiller unit. An eco-friendly bleaching agent to pursue Jackfruit peel with greener nanoscale research has been investigated to prepare green TiO2 nanoparticles. We are reported in various concentrations with and without coating a solar still have been discussed in Jackfruit peel/TiO2 (JPT). The solar still was fabricated and established in comprises of JPT the concentration ratio of experimental studies. The JPT materials analysis of surface morphology, functional energy absorption additives and conducted in chemical structures. Jackfruit peel has an average particle size of 0.116 µm, a zeta potential value of −19.3 mV. SEM image presented absorbent assembly, in which XRD values are 85% crystalline and strong absorption bands are FTIR spectroscopy studies. Since experimental results focus on without and with coating yields of 4.96 L/m2 and 6.12 L/m2, respectively. An experimental performance on the everyday growth with productivity around 102.64%.

WET CHEMICAL GROWTH OF ONE DIMENSIONAL ZnO FILM

The present work focuses on the growth of ZnO films vertically on indium tin oxide substrate using a wet chemical method. The morphological and structural study of the prepared films confirmed the formation of one-dimensional growth with a polycrystalline single-phase hexagonal wurtzite structure. The computed texture coefficient indicates the c-axis growth of the film. The optical spectra study exhibited a strong and sharp characteristics absorption band. The numerical derivative method and the Tauc plot method for the different transition values have been used to compare energy bandgap calculations.

Synthesis and characterization of ZnSe nanorods by coprecipitation method

The present work includes, the synthesis of zinc selenide (ZnSe) nanorods (NRs) using co-precipitation method and characterizations. The ZnSe (NRs) were synthesized using Zn (CH3COOH)2·2H2O and Na2SeO3 as precursors and N2H4·H2O as the reducing agent. The prepared sample were analysed by X-ray diffraction (XRD), transmission electron microscopic technique (TEM), photo luminescence (PL) and UV–Visible spectroscopic techniques. The XRD analysis confirms the formation of hexagonal structure of ZnSe NRs of dimensions; diameter ranges of 90 nm to 170 nm and length 750 nm. TEM micrographs confirm the formation of nanorods. UV–visible absorption spectroscopy was used to determine the optical band gap of ZnSe NRs. The strong and broad absorption band was observed in the wavelength region 320 nm to 470 nm which is corresponding to the band gap of ZnSe nanorods. The PL spectra shows emissions at 543 nm,655 nm,761 nm and corresponding chromaticity diagram indicates that the material emits blue light, it is found suitable for blue LEDs for clinical use and other optoelectronic devices.

Binding affinity of aniline-substituted dodecaborates to cyclodextrins.

A new set of hybrid guest molecules bearing organic and inorganic residues have been studied for their recognition by cyclodextrins in aqueous solution. The guest molecules consist of nitroanilines linked through their amino group to the dodecahydrido-closo-dodecaborate cluster B12H122-, which serves as an anchor group. They show sizable affinity to cyclodextrins, and unexpected photophysical properties, with a very strong and low-energy charge-transfer band. The dodecaborate cluster increases the pKa of the anilines by 5.0 to 5.7 pH units, and the deprotonated forms of the o- and p-nitroaniline derivatives show strong charge transfer absorption bands in the visible part of the spectrum.

Biosynthesis of Silver Nanoparticles from Rhododendron arboreum for Metal Sensing, Antibacterial Assessment, and Photocatalytic Degradation

The nanomaterial industry has focused on green synthetic methods to avoid unpleasant compounds produced during manufacturing, offering eco‐friendly, sustainable, and nature‐derived alternative methods. In this study, silver nanoparticles (Ag NPs) have been synthesized from an aqueous extract of the leaves of Rhododendron arboreum, where the pH of the reaction mixture is found to be crucial. The reaction progress monitored using the UV‐Vis spectrophotometer displayed a strong absorption band at 425 nm at pH 9, suggesting an optimum pH for the synthesis. The Ag NPs thus synthesized were characterized using instrumental techniques. The attenuated total reflectance‐Fourier transform infrared (ATR‐FTIR) spectroscopy showed the presence of phytoconstituents in the aqueous extract, which are believed to be responsible for reducing Ag+ ions to Ag NPs and capping agents on its surface for stability. X‐ray diffraction (XRD) showed a highly crystalline nature, and energy‐dispersive X‐ray (EDX) demonstrated the presence of metallic silver. The scanning and transmission electron microscopy (SEM and TEM, respectively) revealed crystalline morphology and monodisperse Ag NPs of sizes ranging from 23 to 41 nm. Furthermore, the metal‐sensing activity of biosynthesized Ag NPs was evaluated using various metal ions; they were utilized for highly selective and sensitive colorimetric detection of Hg2+ in an aqueous medium among various metal ion solutions tested with the detection limit of 0.5 mM using the UV‐Vis spectrophotometer. Similarly, they were also shown to be effective for the nanocatalytic activity for degradation of methylene blue dye up to 81%. These studies demonstrated Ag NPs as potential candidates for selective detection of mercury in water resources, a tool for sensing the heavy metals and degradation of synthetic dye from industrial effluents in wastewater treatment. Having the high surface‐to‐volume ratio and size‐dependent functionality of Ag NPs, further optimization studies at micromolar and nanomolar detection limits will avail its better industrial utilization. Moreover, biologically mediated Ag NPs can also exhibit good antimicrobial activity against Staphylococcus aureus and Escherichia coli.

Structural, morphological, and electrical investigation of 50 Mrad γ-radiated Ni1-xCdxFe2O4 nanoparticles

The citric acid (C6H8O7) guided sol–gel auto-combustion process was used to successfully prepare Ni1-xCdxFe2O4 nanoparticles, which were then subjected to gamma radiation up to a total dose of 50 Mrad. The cubic spinel structure with the Fd3m-Oh7 space group was revealed by XRD patterns. Using Debye formula, Scherrer's crystallite size (t) was calculated and determined to be 22 nm. The IR spectra of the γ-radiated Ni1-xCdxFe2O4 nanoparticles were used to determine the functional group, which exhibits two strong absorption bands v2 = 426.23 cm−1 and v1 = 550.25 cm−1. The nonuniform grain distribution was indicated by the SEM. The AFM of Ni1-xCdxFe2O4 nanoparticles exposed to 50 Mrad revealed an increase in the dispersion degree of metal ions as a result of the gamma-ray exposure. The semiconducting character of the γ-radiated Ni1-xCdxFe2O4 nanoparticles was revealed by the DC- electrical resistivity as a function of temperature. The gamma radiation induces defects in the material that can be more efficient for many fields.

Structural and Optical Properties of Dy3+ Doped with an Eulytite Type NaBaBi2(PO4)3 Phosphor for White Light Emitting Diodes

A series of NaBaBi(2-x)(PO4)3:xDy3+ eulytite type phosphors with varying doping concentrations were synthesized using a conventional solid-state reaction. The crystalline nature and phase formation of the phosphor were confirmed by the PXRD technique. FESEM was used to examine the surface morphology. UV-DRS measurements were used to quantify the band gap of the host and Dy3+ ion doped phosphors. The phosphors’ photoluminescence properties were thoroughly investigated. According to the excitation spectra, these phosphors show a strong absorption band in the near-ultraviolet (NUV) region, extending from 250 to 450 nm. Under the excitation of 352 nm, the peaks of the emission spectra of Dy3+ ions are located at 485 nm (blue), 575 nm (yellow) and 666 nm (red), corresponding to the magnetic dipole 4F9/2→6H15/2 transition, the electric dipole 4F9/2→6H13/2 transition and the 4F9/2→6H11/2 transition. The optimal concentration of Dy3+ doped phosphor is x = 0.075 and the major concentration quenching mechanism is accomplished by energy transfer between the nearest-neighbour ions. The critical transfer distance (Rc) is estimated to be about 19.01. The Commission International deI’Eclairage (CIE) of NaBaBi1.925(PO4)3:0.075Dy3+ phosphor was calculated to be (x = 0.341 and y = 0.374), which was very close to the “ideal white” (x = 0.33, y = 0.33). Present findings suggest that the phosphor might be a viable option for producing a white-light-emitting phosphor under NUV activation.

Synthesis, crystal structure and electrochemical properties of a new methylammonium sodium decavanate salt Na3(CH3NH3)3[V10O28].(CH3NH2).14H2O

A new hybrid decavanadate Na3(CH3NH3)3[V10O28].(CH3NH2).14H2O was obtained by a simple synthesis in solution and the crystal structure was determined by single-crystal X-ray diffraction. The compound consists of decavanadate anions [V10O28]6- isolated between sodium and methylammonium cations. The UV–Visible absorption, IR spectroscopy as well as electrochemical properties were characterized. The compound crystalizes in a triclinic system (space group P-1) with the unit cell parameters: a = 10.1584(11) Å, b = 10.8123(5) Å, c = 11.1582(7) Å, α = 107.723(4)°, β = 106.811(5)°, γ = 94.238(7)°. UV–Visible absorption spectroscopy shows a strong absorption band at 300 nm. The main IR absorption bands appear at: 954 cm-1, 800 cm-1, 732 cm-1 and 580 cm-1.The electrochemical measurement of this compound shows two reversible one-electron redox process -105 mV (I-I’) and 335mV(II-II’), which was attributed to two consecutive one-electron VV → VIV reductions.

Luminescent Turn-On Upconversion Nanoprobes for Monitoring NADH In Vivo

Mitochondrial damage is implicated with a variety of pathological processes and is featured by the dramatically raised NADH level. To date, the detection and in situ imaging of NADH in living animals is still a challenge. Herein, we designed an upconversion luminescent nanoprobe for the in vivo imaging of NADH. The Nile blue (NB) with a strong absorption band at 500–700 nm can quench the red luminescence of the upconversion nanoparticle at 654 nm by the fluorescence resonance energy transfer effect. Under the presence of NADH, the NB was bleached, so that the fluorescence of the probe was “turned on”. The nanoprobe achieved highly selective detection of NADH, and the in vivo monitoring of NADH was also demonstrated on living mice.

Synthesis and structural characterization of new gold(I) complexes as bioactive and antitumor agents

New mononuclear gold(I) complexes based on 1-thiocarbamoyl-3,5-diaryl-pyrazoline ligands were synthesized and structurally characterized using X-ray crystallography, 13C and 1H NMR studies, and elemental analysis combined with FT-IR and UV-Vis spectroscopy. Complexes 1–3 were prepared in good yields and characterized by X-ray diffraction as neutral mononuclear complexes of the [Au(L)Cl] type with linear coordination geometry around AuI atoms. The UV-Vis absorption profiles of the compounds prepared exhibited two strong absorption bands between 225 and 400 nm, attributed to HOMO → LUMO electronic transitions of the (M + X)LCT type (charge transfer excitations arising from metal plus halogen to ligand) and mixed XLCT + IL type (charge transfer excitations arising from halogen to ligand plus intraligand), based on DFT studies. Assayed for antitumor activity against B16-F10 murine melanoma cells, 4 T1 murine mammary carcinoma cells, and a normal BHK-21 baby hamster kidney cells line, complexes 1–3 exhibited higher bioactivity and selectivity than their respective free ligands. The preliminary results showed these complexes to be good candidates for the development of new metallodrugs based on gold(I) compounds.

Synthesis and characterization study of dual phase mixed zinc cobalt ferrite nanoparticles prepared via chemical co-precipitation method

Nanoparticles of Zinc substituted Cobalt ferrite powders having general formula ZnxCo1-xFe2O4 (x = 0, 0.25, 0.5, 0.75, 1.0) have been produced by using analytical grade nitrates and hexadecyltrimethylammonium bromide (CTAB) as structure directing reagent via Chemical co-precipitation method. The structure and morphology of prepared polycrystalline ferrite nanoparticles were investigated by X-ray diffraction (XRD), Fourier Transform Infrared Radiation (FTIR) and Scanning electron microscopy (SEM) respectively. Thermogravimetric differential analysis (TG/DTA) technique gives information about ferrite phase formation occurs beyond 450 ºC. The XRD analysis confirms the establishment of the cubic spinel structure with the presence of minor secondary phase of α-Fe2O3 (hematite) at a calcination temperature of 650 ºC. The polycrystalline mixed zinc cobalt ferrite nanoparticles showed a dual phase and crystallite size lies in the range 6-11 nm. FE-SEM microstructure shows the nearly spherical polycrystalline nanoparticles with a particle size in between 0.11-0.20 µm. The FT-IR spectra display two significant strong absorption bands nearby in the range of 400 cm-1 and 600 cm-1 on the tetrahedral and octahedral sites respectively. Copyright © 2018 VBRI Press.

Construction of MOF-derived plum-like NiCo@C composite with enhanced multi-polarization for high-efficiency microwave absorption

Nowadays, facing the inevitable electromagnetic (EM) pollution caused by many electronic products, it is urgent to develop high-performance microwave absorbing materials. In particular, the bimetallic carbon-based composites derived from MOFs exhibit excellent microwave absorption potential due to their simple preparation, low cost, adjustable morphology and magnetoelectric synergy mechanism. In this work, we successfully prepared plum-like NiCo@C composite by simple solvothermal method and carbonization treatment, which displays strong absorption (-55.4 dB) and wide effective absorption band (EAB, 7.2 GHz) when the loading is 20 wt%. The plum-like structure greatly enriches the non-uniform interface and the structural anisotropy contributes to the dissipation of electromagnetic waves. At the same time, the band hybridization and magnetic coupling of NiCo@C contribute to the coordination of EM characteristics. Overall, this work proves the feasibility of NiCo@C hierarchical composite in the field of microwave absorbing, and provides insight for the development of high-performance absorbers.

Bis-triazolylchalcogenium-Functionalized Benzothiadiazole Derivatives as Light-up Sensors for DNA and BSA.

A range of bis-triazolylchalcogenium-BTD 3 was synthesized by a copper-catalyzed azide-alkyne cycloaddition of azido arylchalcogenides 1 and 4,7-diethynylbenzo[c][1,2,5]thiadiazole 2. Eight new compounds were obtained in moderate to good yields using 1 mol % of copper(II) acetate monohydrate under mild reaction conditions. In addition, the synthesized bis-triazolylchalcogenium-BTD 3a-3h were investigated regarding their photophysical, electrochemical, and biomolecule binding properties in solution. In general, compounds presented strong absorption bands at the 250-450 nm region and cyan to green emission properties. The redox process attributed to the chalcogen atom was observed by electrochemical analysis (CV techniques). In addition, spectroscopic studies by UV-vis, steady-state emission fluorescence, and molecular docking calculations evidenced the ability of each derivative to establish interactions with calf-thymus DNA (CT-DNA) and bovine serum albumin (BSA). The behavior presented for this new class of compounds makes them a promising tool as optical sensors for biomolecules.

In Situ Dual-Template Method of Synthesis of Inverse-Opal Co3O4@TiO2 with Wideband Microwave Absorption.

A unique porous TiO2 with Co3O4 nanoparticles anchored in (Co3O4@TiO2) is prepared by a dual-templating method for promoting electromagnetic microwave absorption (EMA). The as-prepared Co3O4@TiO2 possesses a three-dimensional (3D) ordered macroporous TiO2 skeleton and plenty of mesopores, as well as small Co3O4 nanoparticles that coexisted in the macropore walls of the TiO2 skeleton. The introduction of Co3O4 can increase the magnetic loss as well as suppress impedance mismatch, resulting in the regulation of the EMA performance. The synergetic effect of the TiO2 porous framework and Co3O4 nanoparticles with proper ratio promote microwave absorption performance. Therefore, Co3O4@TiO2-2 with 25 wt % Co3O4 nanoparticles content displays a strong and ultrawide effective absorption band (EAB) performance. The Co3O4@TiO2-2 presents a strong reflection loss of -53.9 dB at 2.95 mm. Moreover, it obtains a super broad EAB of ∼12.5 GHz at 5.0 mm. This dual-templating approach for a well-controlled porous structure could be a facial strategy for the development of high-performance electromagnetic wave absorbers.

MOF-derived NiFe2S4/Porous carbon composites as electromagnetic wave absorber

The preparation of strong absorption, thin thickness and wide band electromagnetic wave absorbers has always been the focus of research. In this paper, NiFe2S4/PC composites, an electromagnetic wave absorbing material with excellent performance, is prepared by introducing Ni-MOF, Fe and S elements into porous carbon framework. The material has a minimum reflection loss (RLmin) of −51.41 dB and the matching thickness is only 1.8 mm. In addition, the effective absorption bandwidth (EAB) is 4.08 GHz when the thickness is 1.9 mm. The rich interface and good impedance matching characteristics are the main reasons for the excellent absorbing performance of the material. The experimental results show that NiFe2S4/PC composites is a reasonable and effective electromagnetic wave absorption material.

New 1,4-divinylbenzene conjugated truxene dyes possessing D-π-D structure: Synthesis, linear photophysics and two-photon absorption

A series of four 1,4-divinylbenzene linked truxene moieties with different substituents were synthesized by Horner-Wadsworth-Emmons reaction. Their structures were characterized using NMR spectroscopy and HRMS spectrometry. The photophysical properties of these molecules in solvents of different polarity were investigated by UV–vis absorption and fluorescence spectroscopy. These results show that these compounds have strong one-photon absorption bands in the near ultraviolet region displaying relatively high fluorescence quantum yields and large Stokes' shifts. In addition, these compounds possess good solid-state fluorescence, high two-photon absorption cross-section and high thermal stability.

The Transformation by Catalysis of Prebiotic Chemical Systems to Useful Biochemicals: A Perspective Based on IR Spectroscopy of the Primary Chemicals: Solid-Phase and Water-Soluble Catalysts

This study is a continuation of our research on understanding the possible chemical routes to the evolution of life on earth based on the “Selective Energy Transfer” (SET) theory. This theory identifies the specific vibrational mode of the catalyst that is in energy-resonance with a suitable vibrational mode of the reactant. In this way, energy is transferred from catalyst to reactant up to the energy of activation, making possible a particular chemical outcome. Then, we extend this model to the mostly unknown and highly complex environment of the hydrothermal vents, to speculate how prebiotic chemicals, necessary for the evolution of life, could have formed. It is to the credit of the SET theory that it can reflect the slight difference in the catalytic system that gives dramatically very different chemical outcome. It is shown, here, how in model laboratory experiments, methanol gives dimethyl ether (DME) in a 100% yield with Cu exchanged montmorillonite as the catalyst, or a very different product methyl formate (MF) in lower yields, with another Cu2+ ion-exchanged clay mineral (laponite) as the catalyst system. We also show, based on standard laboratory experiments, how COS (carbonyl sulfide) with a strong absorption band at 2079 cm−1 by itself and/or catalyzed by montmorillonite with strong Si-O-Si asymmetric vibration of 1040 cm−1 can react with alpha-amino acids to form alpha-amino acid thiocarbamate (AATC), which we feel could represent the most primitive analogue to coenzyme A (CoASH), a highly versatile bio-enzyme that is vital both for the metabolism and the synthesis of biochemicals in the living system. AATC itself may have undergone evolutionary developments through billions of years to transform itself into coenzyme A (CoASH) and its acetyl ester analogue acetyl coenzyme A (ACoA).

Chiroptical properties of anionic and neutral nickel(II) bis(dithiolene) complexes based on methyl and dimethyl-dddt ligands.

Racemic and enantiopure nickel(II) bis(dithiolene) anionic and neutral complexes based on the methyl-5,6-dihydro-1,4-dithiin-2,3-dithiolate (me-dddt) and dimethyl-5,6-dihydro-1,4-dithiin-2,3-dithiolate (dm-dddt) ligands have been experimentally and theoretically investigated with a special focus on their chiroptical properties. According to the time-dependent density-functional theory (TD-DFT) calculations, the strong near-infrared absorption bands typical for such complexes are only weakly active in circular dichroism (CD), and moreover, they have opposite signs for the axial and equatorial conformations, due to the variation of the angle between the transition electric and magnetic dipole moments, thus leading to the mutual cancellation of their contributions and the absence of these bands in the experimental CD spectra. The influence of the number of stereogenic centers and of the oxidation state of the complexes on their chiroptical properties is highlighted. The solid-state structure of the complex (TMA)[Ni(rac-me-dddt)2 ] (TMA = tetramethylammonium), determined by single-crystal X-ray diffraction analysis, shows a rather unusual cis arrangement of the two dithiolene ligands, with the methyl substituents adopting an axial conformation, which is not the most stable one in the gas phase.

Self-assembly of C60 fullerene molecules in the hexane–xylene solvent system

The behavior of self-assembly of C60 molecules in solutions of C60/hexane/xylene were studied by the methods of refractometry, ultraviolet–visible spectroscopy and dynamic light scattering (DLS). It was experimentally shown that with a slight increase in either the concentration of fullerene C60 or the volume fraction of xylene in a C60/hexane/xylene solution, the refractive index of the medium increases. Increasing the xylene content of the C60/hexane/xylene system leads to significant changes in charge transfer between solute and solvent, which, in particular, exhibit both a positive solvatochromic effect and a hypochromic effect in a strong absorption band at ∼328.8 nm. It was established by the DLS method that with an increase in the concentration of C60 in the C60/hexane solution from 20 to 30 mg/dm3, the maximum radius of the synthesized nanoclusters in solutions changed from ∼6.25 nm to ∼17.2 nm, and also with an increase in the mole fraction of xylene in the C60/hexane/xylene system, the cluster size gradually decreases.

Error removal by energy scaling from hyperspectral images for performance improvement of spectral classifiers

ABSTRACT In the remote sensing community, HyperSpectral (HS) images (HSI) are becoming increasingly popular as the advancement of technology and the consequent reduction of cost make them financially more accessible. The reason for their success is the higher capability they can offer, with respect to multispectral data, to discriminate classes that are spectrally similar. A series of pre-processing steps such as geometric, radiometric and atmospheric corrections are carried out on raw data captured by HS sensors. The processed data is then passed to the data analyst, whose work generally relies on the assumption that the received HS data is ‘clean,’ as all possible corrections have already been implemented; however, corrections are hardly perfect and residual disturbances can still bias the quality of results. At this stage, however, all corrections based on ancillary information have already been made and the possibilities for ‘exogenous’ correction of data are exhausted. More could be possibly done by sourcing additional information from the data itself. In this paper, we propose a simple yet effective additional step for error suppression through energy scaling, termed ‘Error Removal by Energy Scaling’ (ERES). In classification problems, the absolute value of wavelength is often overlooked, except for, e.g. removal of strong absorption bands; yet the value can actually further support the classification process if their physical meaning is tapped. The proposed ERES method is indeed a non-linear scaling method, derived from physical phenomena linked with radiation extinction properties. In ERES, each band is associated with an energy level, that is inversely related to its own wavelength. The associated nonlinear energy information in HSI, neglected in most classification strategies, prevents optimal separation of class-specific spectral signatures, that are generated by the physics of wave-matter interaction. This is especially true for linear classifiers such as Support Vector Machines (SVM). Removing this physics-linked information makes data more suitable to be classified with physics-unaware classification strategies, typically used in down stream remotely sensed data processing. The relevance of the issue, and the benefits of ERES, are discussed and validated in this work over three different datasets, using accuracy improvements on the popular Spectral Angle Mapper and SVM classifiers as a means to gauge the effectiveness of the correction strategy. Results clearly reveal the positive impact of applying ERES to the data before proceeding to classification.