Characteristic Absorption Bands Research Articles

Synthesis of New Schiff Base Compounds and Identification of Their Structures

Schiff bases (imines) have been frequently used in various fields such as medicine, pharmaceutical purposes due to their various biological properties. In this study, nine new imine compounds (3a-h) were synthesized from 1-naphthyl amine with aromatic aldehydes in MeOH and their chemical structures were defined by 1H/13C NMR, IR and elemental analysis studies. We observed a singlet one hydrogen of the imines (–CH=N–) at 8.56–8.86 ppm in the 1H NMR spectra and also carbon of the Schiff bases (–CH=N–) at 158.2-163.4 ppm in the 13C NMR spectra. Also the IR spectra displayed the (–C=N–) characteristic absorption band at around 1600 cm -1. The obtained characteristic peaks at the expected locations proved the structural accuracy of the synthesized new derivative Schiff bases.

Role of Nd3+ ions in TeO2–V2O5–(B2O3/Nd2O3) glasses: structural, optical, and thermal characterization

In this study, undoped and Nd2O3-doped TeO2–V2O5–B2O3 oxide glasses were synthesized and their characterizations were performed. Physical parameters belonging to the glass series having four samples prepared with melt-quenching technique were determined and the changes in structural, thermal, and optical properties with Nd2O3 doping were examined. Density, molar volume, molar refractivity, and metallization criterion values were calculated as physical parameters. Structural properties were examined with XRD and FTIR, and as a result of these examinations, the structure was found to be amorphous and the glass network was observed to consist of TeO4, TeO3, BO3, and BO4 structural units with the help of absorption spectrum within the region of 400–1500 cm−1, and it was also understood that conversions occurred in these structural units with doping. It was determined with DSC thermograms that changes occurred in thermal data with Nd2O3 doping. Transmittance and absorption spectra were used in optical characterization. Seven characteristic absorption bands were found in this glass structure belonging to Nd within the visible region. Moreover, optical band gap, Urbach energy, and refractive index values according to absorption edge were calculated and changes in these novel synthesized glasses due to doping were examined and commented in detail. Data arising as a result of glass characterization were concluded to be due to structural changes in the glass network depending upon the Nd2O3 concentration in glasses and Nd2O3 was present within the structure as the modifier.

Effect of $$\hbox {WO}_{3}$$ nanoparticle doping on the physical properties of PVC polymer

Poly(vinyl chloride)/tungsten oxide ( $$\hbox {PVC}/\hbox {WO}_{3})$$ nanocomposite films were synthesized with different ratio of $$\hbox {WO}_{3}$$ content (0, 0.05, 0.1, 0.2 and 0.3 wt%). The sol–gel method was used to prepare $$\hbox {WO}_{3}$$ nanoparticles (NPs). X-ray diffraction and scanning electron microscope techniques confirmed that the $$\hbox {WO}_{3}$$ NPs were successfully dispersed in a PVC matrix with a single-phase structure. Characteristic absorption bands were observed in infrared spectra for pure PVC and nanocomposites. The morphology of $$\hbox {WO}_{3}$$ was observed using transmission electron microscope. The optical energy band gaps ( $$E_{\mathrm{opt}}$$ ; direct and indirect) were estimated by using Tauc’s formula. It was found that the direct band gap energies decreased from 5.15 to 4.53 eV and the indirect bands decreased from 4.8 to 4.1 eV as $$\hbox {WO}_{3}$$ doping increased, while the Urbach energy ( $$E_{\mathrm{u}}$$ ) increased as $$\hbox {WO}_{3}$$ content increased. It was found that the steepness parameter decreased, which confirms the formation of localized states in the band gap and increasing disorder in PVC polymer samples. The dielectric constant ( $$\varepsilon '$$ ) of the $$\hbox {PVC}/\hbox {WO}_{3}$$ nanocomposite films decreased as frequency increased. At a low frequency region, the loss factor ( $$\varepsilon ''$$ ) has a high value and then sharply decreased as frequency increased, reaching a frequency independent region at high frequency values. The obtained data are very useful for using the investigated samples ( $$\hbox {PVC}/\hbox {WO}_{3}$$ ) as the cores of high frequency transformers with very low dielectric loss.

Impact of selected ionic liquids on corrosion protection of mild steel in acidic medium: Experimental and computational studies

The corrosion potential of three newly studied ionic liquids (ILs) namely, 5-(Trifluoromethyl) dibenzothiopheniumtetrafluoroborate (TDTB), 5-(Trifluoromethyl)dibenzothiopheniumtrifluoromethanesulfonate (TDTM) and 1-Ethyl-3-methylimidazolium ethyl sulfate (EMIM)(ESO4) were investigated for mild steel (MS) in 1 M hydrochloric acid using electrochemical, Fourier trans­form in­frared (FTIR) spec­troscopy and gravimetric tech­niques. The potentiodynamic polarization data shows that the three inhibitor molecules studied possess characteristics that correspond to mixed-type inhibitors but TDTM exhibits more anodic characteristics. Scan­ning electron microscopy (SEM) was used for the surface studies. Remarkable corrosion inhibition of mild steel was also predicted using energy dispersive spectroscopy (EDS). FTIR spectroscopy established the functional group interrelationship showing disappearance of characteristic absorption bands in the adsorption film FTIR spectra. Quantum chemical calculations and Monte Carlo mod­els were utilized to gain more in­sight into the electronic properties of the compounds in rela­tion to the corrosion inhibition effect and the binding and/or adsorption of ionic liquids on the surfaces of MS. The adsorption en­ergy adopts the order: TDTB ≈ TDTM >(EMIM)(ESO4). The numerical val­ues of adsorption energy is −3.72 kcal mol−1, −3.77 kcal mol−1 and −3.04 kcal mol−1 for TDTB, TDTM and (EMIM)(ESO4), respectively.

Protein Leakage Induced Marine Antibiofouling Activity of Biosynthesized Zinc Oxide Nanoparticles

Marine biofouling cause huge economic losses in the aquaculture industries as well as in the marine installation. Biofilm formation is an initial stage of biofouling. Conventional antifoulants including biocides and heavy metal induce toxicity to the aquatic organisms. Marine microorganisms provide a wide range of non-toxic biologically active molecules that helps in synthesis of antimicrobial compounds. The present study was aimed to synthesize zinc oxide nanoparticles (ZnO NPs) using cell free supernatant of Bacillus paramycoides. UV–visible spectrum showed the characteristic surface plasmon resonance absorption band for ZnO NPs at 372 nm. X-ray diffraction shows planes of hexagonal wurtzite structure of ZnO NPs and narrow peaks confirm the crystalline nature of ZnO NPs. Field emission scanning electron microscopic image shows spherical shaped particles in the range of 35–90 nm. Biosynthesized ZnO NPs cause membrane damage in bacterial cells and subsequent protein leakage. ZnO NPs showed remarkable antimicrobial activity against four marine biofilm forming bacteria i.e., Aeromonas hydrophila, Halomonas aquamarina, Escherichia coli and Vibrio parahaemolyticus. Minimum inhibitory concentration value was observed as 10 μg ml−1 with all the bacterial strains. This study also highlights the rapid biosynthesis of ZnO NPs using cell free supernatant of B. paramycoides.

One-Pot Synthesis of Magnetite-ZnO Nanocomposite and Its Photocatalytic Activity

Tri-octyl-amine is known for its potential to assist fabrication of metal and metal oxides nanoparticles. In this work elucidate the synthesis of magnetite-ZnO magnetic nano hybrid by simple one pot reflux method. The synthesized nanoparticles were characterized using X-ray diffraction (XRD), FE-SEM, HR-TEM, vibrating sample magnetometer (VSM), fourier transform infrared spectroscopy (FTIR) and UV–Vis spectroscopy. The X-ray diffraction results confirm the formation of magnetite-ZnO nanocomposites. IR data reveals the characteristic adsorption bands for oxide formation. Magnetic property of the prepared composite was determined by VSM. The photocatalytic activities was performed using methylene blue under UV irradiation. magnetite-ZnO nanocomposite were prepared by using one-pot reflux method with the help of trioctylamine as a solvent and hydrolysing agent. Structutral, morphological, optical and magnetic properties of synthesized nanoparticles were characterized with the help of XRD, FTIR, transmission electron microscopy (TEM), UV–Vis spectroscopy and VSM. X-ray diffraction results confirm the formation of magnetite-ZnO nanocomposites and IR data reveals the characteristic absorption bands for oxide formation. Magnetic property of the prepared composite was determined by VSM. Photocatalytic activities was performed using methylene blue (MB) under UV irradiation and absorbance of MB was found to be reduced for prepared nanocomposite when exposed for longer time. One-pot synthesized magnetite-ZnO nanocomposite and its photocatalytic activity for MB degradation.

Theae nigrae folium: Comparing the analytical performance of benchtop and handheld near-infrared spectrometers

We investigated caffeine and l-theanine, quality characteristics for camellia sinensis, in milled and ground black tea samples with near-infrared (NIR) spectroscopy giving a direct comparison between the performances of benchtop and handheld NIR spectrometers. The constructed partial least squares regression (PLSR) models for all spectrometers were validated by test-set-validation and according to the obtained root mean square errors of prediction (RMSEP). The performances of the spectrometers were as follows: The benchtop spectrometer NIRFlex N-500 (Büchi, Flawil, Switzerland) showed the best results for milled samples with a RMSEP of 0.14% for caffeine and 0.12% for l-theanine. For the ground samples, a RMSEP of 0.17% for caffeine and 0.12% for l-theanine was gained. While the handheld spectrometers MicroNIR 2200 (Viavi Solutions (former: JDS Uniphase Corporation), Milpitas, USA) and the microPHAZIR (Thermo Fisher Scientific, Waltham, USA) both provided good results for the prediction of caffeine in milled samples (RMSEP of 0.22% and 0.26%), only the microPHAZIR was able to satisfactorily determine the caffeine content in ground samples (RMSEP of 0.28%). The investigation of l-theanine with handheld spectrometers did not lead to convincing results, since R2 was 0.75 for milled samples while ground samples could not be calculated. Decisive differences were concluded in how different NIR instruments capture the chemical information on caffeine vs. l-theanine. The handheld spectrometers manifested limited applicability to l-theanine. Deeper insight was obtained through the detailed NIR band assignments of caffeine and l-theanine derived from quantum mechanical simulation. Narrow working spectral region of handhelds omits the characteristic absorption bands of l-theanine. Therefore, information on l-theanine content measured by the evaluated miniaturized spectrometers is insufficient to enable its effective quantification. In contrast, the most characteristic NIR absorption of caffeine matches the working spectral regions of the handheld NIR spectrometers, hence their performance is comparable with the benchtop device.

Effect of fractional substitution of Sb3+ ions on structural, magnetic and electrical properties of cobalt ferrite

The present work suggests the preparation of a series of Sb-substituted cobalt ferrite by the sol–gel auto-combustion method. The phase purity of the samples was evaluated by X-ray diffraction, Raman analysis, and infrared spectroscopy. Raman and infrared spectra exhibited the characteristic absorption bands corresponding to M-O stretching vibrations. The precise chemical composition was verified using the Inductively coupled plasma – atomic emission spectroscopy technique. X-ray photoelectron spectroscopy studies validated the chemical state of present species of the metal ions. The morphology of the samples and their particle sizes were estimated by Scanning electron microscopy and Transmission electron microscopy analysis, respectively. The saturation magnetization decreased with Sb-substitution both at 300 K and 50 K and showed a comparatively higher value at 50 K. The DC electrical resistivity studies showed the semiconducting behavior of the materials and an increasing trend observed with Sb3+ ions content. The increase in dielectric constant with increasing Sb3+ ions concentration and the temperature was observed.

Novel sulphonated poly (vinyl chloride)/poly (2-acrylamido-2-methylpropane sulphonic acid) blends-based polyelectrolyte membranes for direct methanol fuel cells

Proton-conducting and methanol barrier properties of the proton exchange membrane (PEM), as well as the high cost of direct methanol fuel cell (DMFC) components, are the key determinants of the performance and commercialization of DMFCs. Therefore, this study aimed to develop cost- and performance-effective membranes based on sulphonated poly (vinyl chloride) (SPVC)/poly (2-acrylamido-2-methyl-1-propane sulphonic acid) (PAMPS) blends. Such membranes have been simply prepared by blending SPVC and PAMPS solutions, followed by solvent evaporation via casting. Interaction of SPVC with PAMPS was confirmed by different characterization techniques such as Fourier Transform Infra-red (FTIR) and Raman scattering spectroscopy in which the two characteristic absorption bands of sulfonic groups appeared at 1093 and 1219 cm−1 additionally, strong peaks at around 1656 cm−1 attributed to vibration of amide groups of PAMPS portion in the polymer blend. Furthermore, the interaction of SPVC with PAMPS improves the thermal properties along with ion exchange capacity in turn decreasing the methanol permeability through the membrane in comparison with the SPVC membrane. The IEC of PVC and Nafion 117 membranes were 1.25, 0.91 meq/g; respectively. And the maximum water uptake of PVC and Nafion 117 membranes were 75 and 65.44%; respectively. Methanol permeability value of 7.7 × 10−7 cm2/s which was noticeably lower than the corresponding value recorded for Nafion® (3.39 × 10−6 cm2/s). Therefore, these fabricated membranes can be considered a low-cost efficient candidate for use in DMFC, especially for its capability to resolve the methanol cross-over issue.

Plásticos que fizeram história - a contribuição das ciências da conservação para a história da Indústria Portuguesa dos Plásticos

The plastic objects from our cultural heritage are material testimonies of our history, technology and industry. Still, in Portugal, there is no museum of plastics, and the collections are spread through private collectors and industries. The research project, 'The Triumph of Bakelite - Contributions to a History of Plastics in Portugal', aims at creating this museum. To this end, the research work gave rise to the exhibition, 'Plasticity - A History of Plastics in Portugal', in Museu de Leiria in 2019. This study focuses on the contribution of conservation science for the writing of this history and preparation of ca. 150 historical plastic objects for display. Bakelite, melamine, polyethylene, polypropylene, polystyrene and plasticized polyvinyl chloride are just a few examples of the polymers identified by infrared spectroscopy. This identification was crucial to tell the history of the plastics industry in Portugal. Both the spectra and characteristic absorption bands of each polymer are presented.

Quantum Chemical Analysis of the Processes of Synthesis of Vanadium Oxide Structures on the Silica Surface

Based on a combination of quantum chemical simulation and experimental studies, the formation of vanadium oxide structures on the silica surface when sequentially treated with VOCl3 and H2O vapors was analyzed. The synthesis products were identified by IR spectroscopy. Changes in the composition and structure of the resultant surface species according to the process temperature and VOCl3 vapor pressure in the reactor were predicted by quantum chemical methods. By the example of the synthesis at 473 K in a flow-through system and study of the chemical composition and structure of the new functional groups formed on the surface, a good agreement between the experimental and calculated data was demonstrated. The results of IR spectroscopic studies of the samples synthesized were processed using quantum chemical approaches. The characteristic IR absorption band due to vibrations of the bridging bonds of vanadium atoms with the Si–O–V matrix, localized at 920–945 or 960 cm–1 depending on the structure of the surface sites, was used as the basis for identification of the surface vanadium oxide groups.

Synthesis of Ni doped iron oxide nanoparticles and their dielectric properties

Sol-gel method was adopted for the formation of magnetite and metal doped nanoparticles. The Synthesized nanoparticles were confirmed by using XRD, FE-SEM, FTIR and UV-Vis spectroscopic techniques. The X-ray diffraction results confirm crystalline structure and the size of the synthesized nanoparticles. IR data reveals the characteristic absorption bands for oxide formation. Dielectric properties of the prepared composite were determined by impedance analyser. Significant improvement of dielectric properties can be obtained when we incorporated polymer matrix in metal oxide nanoparticles.

Mercaptoalkanoic Acid‐Induced Band Gap Attenuation of Copper Selenide Quantum Dot

AbstractCopper selenide quantum dot (CuSeQD) materials functionalised with mercaptoalkanoic acids {3‐mercaptopropionic acid (3‐MPA), 6‐mercaptohexanoic acid (6‐MHA) and mercaptosuccinic acid (MSA)} were synthesized by a reproducible aqueous colloidal technique at room temperature. The impact of the capping agents on the size and the crystallinity of the CuSeQD materials, were investigated by small angle X‐ray scattering (SAXS) and X‐ray diffraction (XRD) spectroscopic techniques, respectively. SAXS results confirmed that 6‐MHA‐CuSeQD had the smallest average particle core size when dried, whereas MSA‐CuSeQD had the smallest size in aqueous solution, though with a tendency to aggregate. Dynamic light scattering (DLS) measurements indicated strong bonding of the capping agents to CuSe particles, with MSA being the weakest binding agent, as confirmed by comparatively, low Zeta potential(ζ=−31.1 mV) and high polydispersity index (0.469) values. UV‐Vis absorption studies confirmed a large blue shift of the band gap for the QD compared to the bulk material, with characteristic absorption band (λ) and direct band gap (Egd) values being (λ=435 nm, Egd=8.0 eV), (λ=400 nm, Egd=5.6 eV) and (λ=340 nm, Egd=4.0 eV), for 6‐MHA‐CuSeQD, 3‐MPA‐CuSeQD and MSA‐CuSeQD, respectively. As supported by the formal potential values for 6‐MHA‐CuSeQD (E0′≈120 mV), 3‐MPA‐CuSeQD (E0′≈159 mV) and MSA‐CuSeQD (E0′≈183 mV), the smaller the particle size, the lower the potential required for the application of the quantum dots in an electron transfer process.

Self-Assembly of Pseudo-Isocyanine Chloride as a Sensor for Macromolecular Crowding In Vitro and In Vivo.

Pseudo‐isocyanine chloride (PIC) is a cationic dyestuff that exhibits self‐assembly in aqueous solution, promoted either by increasing the PIC concentration or by decreasing the temperature. PIC‐aggregates exhibit a characteristic and sharp absorption band as well as a fluorescence band at a wavelength of 573 nm making PIC an interesting candidate to analyze the self‐assembly process in various environments. The present work developed PIC‐based, synthetic model systems, suitable to investigate how macromolecular crowding influences self‐assembly processes. Four synthetic additives were used as potential crowders: Triethylene glycol (TEG), polyethylene glycol (PEG), Ficoll 400 as a highly branched polysaccharide, and sucrose corresponding to the monomeric unit of Ficoll. Combined UV/Vis spectroscopy and time‐resolved light scattering revealed a strong impact of crowding based on excluded volume effects only for Ficoll 400. Sucrose had hardly any influence on the self‐assembly of PIC and PEG and TEG impeded the PIC self‐assembly. Development of such a PIC based model system led over to in‐cell experiments. HeLa cells were infiltrated with PIC solutions well below the aggregation threshold in the infiltrating solution. In the cellular environment, PIC was exposed to a significant crowding and immediately started to aggregate. As was demonstrated by fluorescence imaging, the extent of aggregation can be modulated by exposing the cells to salt‐induced osmotic stress. The results suggest future use of such a system as a sensor for the analysis of in vitro and in vivo crowding effects on self‐assembly processes.

Removal of chromium ions by functional polymers in conjunction with ultrafiltration membranes

Abstract In the current research water-soluble functional polymers (WSFP) were prepared via radical polymerization and purified by fractionation through ultrafiltration membranes with different molecular weights cut off (MWCO) of 30 and 100 kDa. The WSFPs were poly(3-acrylamide propyl) trimethyl ammonium chloride, P(ClAPTA), poly(2-acrylamido-2-methyl-1-propane sodium sulfonate, P(AMPSNa), and poly(3-methacrylamino propyl) dimethyl 3-sulfopropyl ammonium hydroxide, P(HMPDSPA). These polymers were characterized by Fourier transformed infrared spectroscopy (FT-IR) and thermogravimetry analysis (TGA). Using liquid-phase polymer-based retention technique (LPR), chromium [Cr(III) and Cr(VI)] retention was studied as a function of pH, polymer and chromium concentration, selectivity, maximum retention capacity, chromium elution capacity, and polymer regeneration through sorption and desorption studies. Results of FT-IR showed the characteristic absorption bands of the synthesized polymers. The decomposition temperatures of P(ClAPTA) were at 303.1 °C, and for P(AMPSNa) three decompositions temperatures were registered at 190.5 °C, 223.2 °C, and 304.8 °C. P(HMPDSPA) presented two important decomposition temperatures at 292.4 °C and 391.7 °C, respectively. Concerning to the retention of Cr(VI), it was maximal (100 %) when P(ClAPTA) was studied at pH 6. The maximum retention of Cr(III) (100 %) was achieved by P(AMPSNa) at pH 3. The optimum polymer:Cr mole ratio obtained was 10:1 for both Cr(VI) and Cr(III). The retention of Cr(VI) decreased due to the presence of interfering ions, and the hydrodynamic flow was almost constant during the ultrafiltration of polymer-Cr macromolecule.

Ground and Excited States of Gas-Phase DNA Nucleobase Cation-Radicals. A UV-vis Photodisociation Action Spectroscopy and Computational Study of Adenine and 9-Methyladenine.

Cation radicals of adenine (A•+) and 9-methyladenine (MA•+) were generated in the gas phase by collision-induced intramolecular electron transfer in copper-terpyridine-nucleobase ternary complexes and characterized by collision-induced dissociation (CID) mass spectra and UV-vis photodissociation action spectroscopy in the 210-700 nm wavelength region. The action spectra of both A•+ and MA•+ displayed characteristic absorption bands in the near-UV and visible regions. Another tautomer of A•+ was generated as a minor product by multistep CID of protonated 9-(2-bromoethyl)adenine. Structure analysis by density functional theory and coupled-clusters ab initio calculations pointed to the canonical 9-H-tautomer Ad1•+ as the global energy minimum of adenine cation radicals. The canonical tautomer MA1•+ was also calculated to be a low-energy structure among methyladenine cation radicals. However, two new noncanonical tautomers were found to be energetically comparable to MA1•+. Vibronic absorption spectra were calculated for several tautomers of A•+ and MA•+ and benchmarked on equation-of-motion coupled-clusters excited-state calculations. Analysis of the vibronic absorption spectra of A•+ tautomers pointed to the canonical tautomer Ad1•+ as providing the best match with the action spectrum. Likewise, the canonical tautomer MA1•+ was the unequivocal best match for the MA•+ ion generated in the gas phase. According to potential-energy mapping, MA1•+ was separated from energetically favorable noncanonical cation radicals by a high-energy barrier that was calculated to be above the dissociation threshold for loss of a methyl hydrogen atom, thus preventing isomerization. Structures and energetics of all four DNA nucleobase cation radicals are compared and discussed.

Eco-friendly approach to control dengue vector Aedes aegypti larvae with their enzyme modulation by Lumnitzera racemosa fabricated zinc oxide nanorods

Aedes aegypti mosquito species is a primary vector for dengue, chikungunya and Zika infections, and vector control is the only key approach for reducing their transmission. The present study emphasizes on environmental friendly approach for the fabrication of zinc oxide nanorods (ZnO NRs) using aqueous extract of Lumnitzera racemosa flower buds (LB) as a reducing and stabilizing agent. ZnO NRs were examined by UV–Vis spectroscopy with characteristic absorbance band at 373.82 nm and bandgap of 3.25 eV. FT-IR analysis revealed the functional groups associated with ZnO NRs. The crystallinity of LB-ZnO NRs was further investigated using X-ray diffraction. The Zeta potential displayed a surface charge of − 23.5 mV on NRs. Energy dispersive spectra analysis and SEM analysis confirmed the formation of ZnO NRs whilst TEM highlighted the average length and diameter in the range of 250–300 nm and 45–50 nm respectively. LB-ZnO NRs were found to be efficacious against Ae. aegypti 4th instar larvae with LC50 of 24.74 μg/ml. Decreased acetylcholinesterase (60.6%) and glutathione S-transferase (24.4%) activities were also evaluated in Ae. aegypti larvae which were exposed to synthesized LB-ZnO NRs with no genetic aberrations. All these outcomes propose the potential employment of LB-ZnO NRs in mosquito control, as well as an effective alternative to insecticide resistance.

Characterization of raw and thermally treated Nigerian kaolinite-containing clays using instrumental techniques

Thermal behavior, surface area, oxide, mineralogical composition, and structural functional groups of raw and thermally treated five local kaolin clays [Ijero-Ekiti (IJ), Ikere-Ekiti (IK), Isan-Ekiti (IS), Abusoro (AB) and Odigbo (OD)] from two states in South-West Nigeria were studied in order to determine their potential uses. These properties were measured using thermogravimetric analysis coupled with differential thermal analysis (TGA/DTA), surface area and porosity analysis, X-ray fluorescence (XRF), X-Ray Diffractometry (XRD) and Fourier Transform infra-red spectroscopy (FTIR) respectively. The TGA/DTA showed major mass losses and broad endothermic bands at temperatures 390–700 °C, which were associated with dehydroxylation of kaolinite and other clay minerals. Thermal treatment increased the surface area of the raw clays. The XRF results showed oxides of kaolinite, illite, quartz, feldspar, hematite, anatase and the phases were confirmed by XRD. The FTIR spectra displayed the characteristic absorption bands of the minerals. Combining the obtained results, Ijero-Ekiti clay was identified as feldspar (albite)-quartz containing clay, Ikere-Ekiti and Isan-Ekiti clays as kaolinite-dominated clays, Abusoro clay as kaolinite-illite-montmorillonite-containing clay and Odigbo clay as kaolinite-illite-containing clay. The TGA/DTA, XRD and FTIR indicated that crystalline kaolinite in the clays were converted into amorphous metakaolinite after thermal treatment. Based on the properties displayed, clays from IK, IS, AB and OD deposits can be thermally treated to form useful supplementary cementitious and geopolymer materials to make binders in building and construction while clay from IJ deposit can be a potential raw material for ceramic production.

InVivo Bioengineering of Fluorescent Conductive Protein-Dye Microfibers.

SummaryEngineering protein-based biomaterials is extremely challenging in bioelectronics, medicine, and materials science, as mechanical, electrical, and optical properties need to be merged to biocompatibility and resistance to biodegradation. An effective strategy is the engineering of physiological processes in situ, by addition of new properties to endogenous components. Here we show that a green fluorescent semiconducting thiophene dye, DTTO, promotes, in vivo, the biogenesis of fluorescent conductive protein microfibers via metabolic pathways. By challenging the simple freshwater polyp Hydra vulgaris with DTTO, we demonstrate the stable incorporation of the dye into supramolecular protein-dye co-assembled microfibers without signs of toxicity. An integrated multilevel analysis including morphological, optical, spectroscopical, and electrical characterization shows electrical conductivity of biofibers, opening the door to new opportunities for augmenting electronic functionalities within living tissue, which may be exploited for the regulation of cell and animal physiology, or in pathological contexts to enhance bioelectrical signaling.

Magnetic, elastic, dielectric, microwave absorption and optical characterization of cobalt-substituted nickel spinel ferrites

Magnetic, elastic, dielectric, microwave absorption and optical properties of nickel cobalt ferrites Ni1-xCoxFe2O4(x=0.0,0.15,0.30,0.45,0.60,0.75,0.90,1.0) synthesized using Pechini’s sol–gel method are investigated. Saturation magnetization, coercivity and Curie temperature increased with doping of cobalt. An optimized combination of high MS (86.12 emu g−1) and lower coercivity (694.7 Oe) was obtained for composition NC 0.90. Curie temperature increased from 602 °C to 705 °C as amount of Co increased from 0.0 to 1.0. In FT-IR spectrum, characteristic absorption bands were observed in 400–600 cm−1 range. Impedance analyzer was used to determine dielectric and impedance properties in 20 Hz–120 MHz frequency range. The prepared ferrites were evaluated for their applications in 12.4–18 GHz frequency band using vector network analyzer (VNA). Minimum reflection loss of −44.48 dB at 15.74 GHz frequency was obtained for composition NC 0.90. Optical spectra at excitation wavelength of 350 nm show sharp peaks around 330 nm in all the compositions.