A green and efficient synthetic pathway was developed to prepare nickel@Luffa nanocomposite. Thymus vulgaris extract was used to functionalize the surface of Luffa fibers with hydroxyl, carbonyl, and amide groups, which assisted in the adsorption of nickel ions. The scanning electron microscope images revealed that nickel nanoparticles grew as aggregates of semi-spherical particles and randomly dispersed on the Luffa fibers. The X-ray diffraction pattern of the nickel@Luffa nanocomposite showed the diffraction pattern of a face-centered cubic Ni crystal. XPS spectrum indicated the formation of metallic Ni at the Luffa surface. The prepared nickel@Luffa was used to catalyze the degradation of 4-nitrophenol, methyl orange, bromophenol blue and a mixture of both. The reaction rate constant for nickel@Luffa nanocomposite was calculated as 15.47×10-3 sec-1 at pH=10 and even after ten cycles its conversion was about 90%. The nickel nanoparticles could be recycled/ reused for ten catalytic cycles with adequate catalytic activity. Such synthetic pathways encourage the application of renewable natural resources to fabricate separable/recyclable heterogeneous catalyst for many important reactions. The proposed nanocomposite is industrially applicable and environmentally-benign, fulfilling the requirements for the sustainable development.

In this study, we utilized terahertz time-domain spectroscopy (THz-TDS) to study the radiation-induced protein deformation. The absorption coefficient spectra obtained from THz-TDS measurements in the frequency range (0.06–2 THz) was fitted using the Lorentzian model. The absorption coefficient fitting data was used to identify the α-helix and β-structure relative contributions in the protein secondary structure of the kidney tissue of rats irradiated with 10-cGy and 2-Gy X-ray separately or in combination. Our data show that 2-Gy X-irradiation leads to an increase in the β-structure contribution associated with a decrease in the α-helix contribution as indicated by the fitting parameters extracted from fitting the absorption coefficient α(ω) spectra with the Lorentzian function. The results point out that there is a strong correlation between the strength of the hydrogen bonds located between or inside the polypeptide chains of the extended β-sheet and α-helix, respectively, and the absolute value of the absorption coefficient α(ω), the refractive index, and the dielectric constant. The lowest refractive index and dielectric constant are recorded in the 2-Gy-irradiated group followed by the 10-cGy–2 Gy-irradiated group while the least effect was recorded in the 10-cGy-irradiated group. These data provide evidence of the adaptive effect of the 10-cGy X-irradiation delivered 24 h prior to the 2-Gy x-irradiation.

Proteins comprise almost half of the weight of plasma membrane and are responsible for preforming various membrane functions. Functionality of the protein is sensitive to its structure. Therefore, modification of the protein conformation can abrogate its function. We demonstrate the induction of radioadaptation in the kidney of low-dose irradiated rats in the form of diminishing the alterations of the protein secondary structure. The FTIR amide I absorption band fitting using Lorentz function was used to identify the various components of the protein secondary structure. FTIR data show changes in amide I band position, amide I/amide II area ratio, FWHM of amide I band, the shifts in the beta-structure bands at 1611, 1623, 1634 cm(-1) and the decrease in the beta/alpha ratio. 2Gy x-irradiation lead to an increase in the beta-structure at the expense of the alpha-helix. The effect of 2Gy x-irradiation was diminished when preceded with 100 mGy x-rays 24 h earlier. The data provide clue of induction of radioadaptation in the kidneys of whole-body irradiated rats following receiving a low priming dose 24 h prior to a challenging dose.

In this study, we investigate the abscopal effect induced in the brain, lung and kidney as a result of partial irradiation of experimental animals with 2 Gy gamma-rays. Modifications in the protein secondary structure were used as indicator for the abscopal effect. FTIR spectroscopy and analysis of the amide I and amide II absorption bands suggested possible modifications in the protein secondary structure in the brain and kidney following irradiation. Significant shift in the amide I band was recorded only in the brain. However, the amide I/amide II band area ratio for the three organs examined varied differentially in the irradiated groups as compared with the shamirradiated group. Employing the lorentzian model to analyze the amide I band of the FTIR spectra, we dissected the amide I band into its components, each component represents one form of the protein secondary structure. Calculation of the weight percentage contribution of each of the protein secondary structure revealed decrease in the alpha-helix contribution associated with equivalent increase in beta-sheets and turns/random coils contributions in the brain and kidney, however the response was more evident in the brain. No change in the alpha-helix or beta-sheets contributions was reported in the lung following irradiation. The data suggest the induction of abscopal effect in the brain and kidney rather than the lung in the form of protein conformation modification. The data also indicate that the abscopal effect is comparable to the effect of direct irradiation in both of the brain and kidney.

Here, we present an optical conductivity study on poly(3,4-ethylene dioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) and PEDOPT:PSS modified with ethylene glycol (EG-PEDOPT:PSS) thin films doped with 0.5, 1, and 2 wt% single-walled carbon nanotubes (SWCNTs) in wide frequency range (0.1-1500 THz). The low frequency part of sigma(omega) spectrum is composed of two components: narrow sigma(LMD1)(omega) and broad sigma(LMD2)(omega) contributions where they mimic conductivity of SWCNTs and PEDOT:PSS or EG-PEDOT:PSS, respectively. At the DC limit, the PEDOT:PSS and EG-PEDOT:PSS do not contribute to the total conductivity sigma(Total)(0) and the sigma(Total)(0) comes from SWCNT' s free electrons. The 0.5 wt% doped samples showed lower conductivities as compared with pure SWCNTs, where the transferred free electrons from the SWCNTs are blocked by reducing the PEDOT:PSS or EG-PEDOT:PSS. For the 1 wt% and 2 wt% composites, there are enough free electrons to reduce the polymer and the rest enhance the total conductivity of the system. The effect of electrons transfer blocking becomes less significant in this case leading to conductivity enhancement.

We present reflectivity measurements on monoclinic MoO2, orthorhombic α-MoO3, and monoclinic β-MoO3 in a wide frequency range of 190–2500 nm. The extracted optical conductivity [σ(ω)] showed that MoO2 has a metallic character while α-MoO3 and β-MoO3 have an insulating behavior. In addition, the photochromic properties of both α-MoO3 and β-MoO3 have been studied. The σ(ω) spectra for both samples showed a different spectral weight of the optical transition due to the formation of color center bands, which formed as a result of UV exposure. The spectral weight of optical transition from the bulk sixfold cations Mob5+ to Mo6+ cations is higher in case of the illuminated β-MoO3 sample than the illuminated α-MoO3 sample. The XRD results showed that both α-MoO3 and β-MoO3 were transformed to monoclinic molybdenum oxide dihydrate (H4MoO5) after exposure to UV irradiation in humid air. The σ(ω) spectra revealed that photoinjection of hydrogen into the β-MoO3 film is higher than in the case of the α-MoO3 film. In addition, the time domain fluorescence lifetime imaging microscopy data showed that the lifetime due to the optical transition from surface fourfold cations Mos5+ to Mo6+ cations in the case of illuminated β-MoO3 is higher than that for the illuminated α-MoO3 for the same optical transition. Meaning that, in the case of illuminated β-MoO3, the surface Mos5+ cations disperse and penetrate into the bulk, lowering the spectral weight of the [Mos5+ Mos5+] dimers and enhancing the spectral weight of the bulk centers.

We present non-linear optical properties of graphene oxide (GO) doped with low chirality metallic single walled carbon nanotubes (m-SWCNTs) thin films. The weight percentage of the m-SWCNTs was 5, 10, and 20 wt%. High-resolution transmission electron microscope (HRTEM), high resolution scanning electron microscope (HRSEM), Raman, and UV–vis spectroscopy were used to characterize the prepared samples. We have investigated their nonlinear optical properties using open and closed Z-scan technique at Nd:YAG laser at 1064 nm laser pulses (7 ns, 10 Hz). The nonlinear absorption coefficient β, nonlinear refractive index n2, and third order nonlinear susceptibility χ3 were calculated. The results show that all samples exhibit reverse saturable absorption (RSA) because of increasing metallicity and/or partial reduction of GO during laser illumination. The nonlinearity response of the GO/m-SWCNT films increase as the m-SWCNTs percentage increases. The high non-linear optical parameters of the GO/m-SWCNTs films make them as superior candidates for near-infrared (NIR) laser protection applications.

We present transmission measurements on chirality enriched semiconducting (12,1) and (13,2) single-walled carbon nanotubes (CE-s-SWCNTs) and CE-s-SWCNTs doped with iodine (I-2@CE-s-SWCNTs) and bromine (Br-2@CE-s-SWCNTs) in wide frequency range from 0.1 to 40 THz. The real part of the optical conductivity sigma(real)(omega) was fitted using Drude-Lorentz model. The Drude (D) term in the CE-s-SWCNTs was attributed to the presence of metallic tubes traces in the sample. The D/scattering rate(gamma(D)) ratio was increased by a factor of 1.13 and 2.35 with iodine and bromine p-doping, respectively. This increase was compensated by large increase in D term leading to an increase in the optical conductivity at the DC limit (sigma(DC)), growing from 186 Omega(-1)cm(-1) for the CE-s-SWCNTs to 203 and 426 Omega(-1)cm(-1) for the I-2@CE-s-SWCNTs and Br-2@CE-s-SWCNTs, respectively. In addition, the plasmon peak was shifted to higher frequencies and gains more spectral weight with doping. The calculated optical parameters determine that iodine and bromine create acceptor levels above the top of the CE-s-SWCNTs valence band by 0.04 and 0.08 eV, respectively, shifting the Fermi level. The high sigma(DC) value of the Br-2@CE-s-SWCNTs is due to the higher electronegativity of bromine which enables removal of more electrons from the valence band of CE-s-SWCNTs to bromine acceptor levels. (C) 2021 Elsevier Ltd. All rights reserved.

In this paper, the effect of feeding gas type on the dynamics of channel spark pulsed electron deposition system is investigated. Electrical, magnetic, and optical characterisations of the system were measured for different feeding gases, oxygen (O2), nitrogen (N2), and argon (Ar). The discharge current for each gas type was measured with maximum value of 1189 A for O2 at -13 kV applied voltage. The discharge current and voltage waveforms were simulated by LRC circuit theory. Effect of gas pressure on the maximum discharge current and total inductance was also investigated. The beam current investigated by faraday cup and reached maximum electron beam current of 136 A for O2 gas. Two magnetic pickup coils were employed for the measurements of beam kinetic dynamics and the measured beam speed was around 0.4× 106 m/sec. Electron beam plasma density was calculated from faraday cup and magnetic coils signals and found to be 1.96×1020 m-3. Optical emission spectra were also measured to identify reactive species and its role in electron beam interaction with graphite target for thin film deposition application. The ability of using the system for thin film deposition is demonstrated by depositing amorphous hydrogenated carbon (a-C:H) films over silicon substrates.

We present transmission measurements on silver@polyaniline (Ag@PANI) core@shell nanocomposites over a wide frequency range from terahertz to ultraviolet (0.001-6.2 eV). The Ag@PANI core@shell nanocomposites were prepared using solid-state reaction by mixing aniline sulfate (ANS) with 2.5, 5, 7.5, and 10 wt % AgNO3. The nanocomposites were characterized by transmission electron microscope, ultraviolet/visible spectroscopy, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy. The optical conductivity sigma(omega) was fitted using the localization-modified Drude model together with the Lorentzian function. The incremental loading of AgNO3 leads to an increase in the Drude conductivity (sigma(LMD)) and decrease of the scattering rate (gamma(D)) due to the increase of electron delocalization of protonated quinoid imine units. In addition, the densities of states N-EF at the Fermi level are increased from 1.7 to 2.7 per eV per formula unit, while the conduction bandwidth W is decreased from 0.7 to 0.4 eV with increasing the AgNO3 from 2.5 to 10%. The optically determined band parameters suggest that the addition of AgNO3 modifies the energy state of the Ag@PANI core@shell nanocomposites close to the Fermi energy modifying the half-filled polaron band.

We present an electrical and spectroscopic characterization of Acetylene plasma used for deposition of different forms of hydrogenated amorphous carbon (a-C:H) films at different discharge powers. Asymmetric radio frequency capacitively coupled plasma source driven by 13.56 MHz used for generation of the discharge. Fast Fourier transformation of the experimentally measured discharge current waveforms shows several harmonics of the driving frequency, the number and amplitude of these harmonics depends on the experimental conditions. The plasma series resonance (PSR) oscillations generated such harmonics leading to an enhancement of ionization process. Optical emission spectroscopy results showed strong emissions intensities from C 4 H 2 + which varied with both power and pressure, the presence of these emissions attributed to the PSR effect. The formation and transformation of the films from polymeric a-C:H to graphitic a-C:H at different discharge powers was confirmed by Raman, FTIR and optical absorption spectroscopy. For the first time we constructed a ternary phase diagram of the a-C:H films based on the relative intensity ratio of [I(C 4 H 2 + )/I(CH)] to provide quantitative information about the types of the deposited films. We pointed out that the C 4 H 2 + ionic species play the major role in the films formation and transformation process.

Spectroscopic studies were carried out on monolayer, trilayer, and few layers of graphene sheets to investigate the effect of plasma parameters such as the electric current, substrate temperature, and the effect of the acetylene and hydrogen gases mixture ratios on the geometrical structure, electronic and optical properties of the synthesized films. Single-, triple- and few-layer graphene sheets were deposited on copper substrates by using self assembled direct current plasma enhanced chemical vapor deposition (DC-PECVD) reactor. The deposited graphene samples were characterized by high resolution transmission electron microscope (HRTEM), X-ray diffraction (XRD), Raman and photoluminescence (PL) spectroscopy. The results demonstrated that the number of graphene layers as well as the defects ratio of sp(2) hybridization size domain have been changed notably with changing the preparation conditions, where a single layer graphene sheet was obtained at preparation conditions of H-2:C2H2 ratio of 100:4 sccm, plasma electric current of 130 mA, and substrate temperature of 750 degrees C. The recorded PL spectrum for the single layer graphene shows one weak and broad band at 348 nm. We have recorded an exponential relation between the blue shift of the PL peak and the changing in the size domain of the sp(2) hybridization.

Thin films from polymeric and graphitic hydrogenated amorphous carbon (a-C:H) were deposited over a glass substrate from acetylene (C2H2) plasma by using a conventional plasma enhanced chemical vapor deposition (PECVD). Radio frequency capacitively coupled plasma (RF CCP) source operating at a frequency of 13.56 MHz was used for generation of the discharge. Optical emission spectroscopy (OES) results showed strong optical emissions from diacetylene ion C4H2+ at a wavelength of 506 nm. The energy dispersive X-ray (EDS) measurements illustrated that the carbon content in the deposited films increased with increasing of power. The Raman and IR results demonstrated that the films deposited at low bias voltages 340 V are so called polymeric a-C:H with high sp(3) fraction and high hydrogen content, while the films deposited at high bias voltages 877 V are so called graphitic a-C:H with low sp(3) fraction and low hydrogen content. Quantitative information were obtained from fitting the high asymmetrical vibrational modes of Raman and IR spectra by using Fano model expression together with Lorentzian function. The results presented here point out that there is a relation between the intensity of C4H2+ ion emissions and the deposited films properties.

Photochromic studies on tungsten oxide (WO3) with single and mixed phases are performed in the mid-infrared frequency range 400-4000 cm(-1). Different crystalline phases of WO3 are synthesized by hydrothermal technique using two different procedures. Monoclinic and hexagonal (m-h-WO3) mixed phases and hexagonal single phase are produced. The optical properties of these two phases have been compared with the nanostructured WO3 thin films synthesized by pulsed laser deposition technique. The crystalline nature and crystallite size of the samples are obtained by X-ray diffraction. The High Resolution Transmission Electron Microscope HRTEM is used to demonstrate the sizes, morphologies and electron diffraction of the two powders micro-structures. Spectroscopic studies on the nano-crystalline m-h-WO3, and h-WO3 are executed in the infrared, visible and ultraviolet frequency range. The FTIR reflection of colorless samples before and after exposure to UV light irradiation at different times are recorded. Drude-Lorentz (DL) model have been used for fitting the reflection spectra of the samples under investigations. Quantitative information about the different stretching vibrational bands are obtained from the fitting curve and its component. Using DL model, the optical conductivity have been estimated from the optical parameters obtained from the data extracted from the differential complex IR analysis in the frequency range of 400-4000 cm(-1). The results illustrate that the optical conductivity of samples are significantly changed due to their exposure to UV light at different times.

There is a growing interest over the environmental safety and mass-production of polymer nanocomposites. Solvent-free synthetic pathways are considered as promising alternative green techniques because of their high efficiency, simplicity and negligible liberation of hazardous waste. A new synthetic route has been developed to synthesize silver@polypyrrole core@shell nanocomposites at ambient condition. The silver nanoparticles are directly synthesized via solid-state reaction with poly(vinylpyrrolidone) and then pyrrole is polymerized in Ag/PVP powder. The band gap value decreases with the increased addition of pyrrole in the preparation step due to the formation of more silver nanoparticles. Scanning and transmission electron microscope confirm the formation of core@shell structure. The negatively charged carbonyl group of poly(vinylpyrrolidone) can bind to polycationic polypyrrole by an electrostatic effect to form the core@shell structure. The terahertz spectroscopy characterizes the prepared core@shell nanocomposites that are well fit to the Drude-Smith model. The DC optical conductivity in the terahertz range (0.3-2 THz) is increased with increasing Py addition.

Simple pulsed spray pyrsolysis (PSP) technique is used to prepare pure nanostructured zinc oxide (ZnO) thin films at different deposition temperatures and spraying times on glass substrates. XRD measurements show polycrystalline ZnO hexagonal wurtzite phase preferably oriented perpendicular through c- axis along (002) plane. SEM images demonstrate the formation of highly ordered hexagonal nanorods with a crystallite sizes ranged from 40 to 500 nm depending on the film thickness. Optical measurements show transmittance of nearly 90% at low thicknesses (189.1µm) and about 60% for higher thickness (233.8 µm) with a calculated energy band gap values spanning from 2.85 to 3.20 eV. Photocatalytic activity is performed on selected ZnO samples have highly oriented nanorods with large hexagonal cross-section area. Photocatalytic activity takes place on etched and as prepared ZnO film samples by monitoring photodegradation process of methylene blue MB using double beam spectrophotometer. Etched samples show higher photo activity than non- etched ones.

A systematic study on sulfonamide derivatives with salicylamide core is presented for possible use in pharmaceutical applications. The molecular structure of eight different compounds has been investigated by FTIR in the frequency range 4000-400 cm-1 to recognize the possible geometrical shape of the molecules needed to uniquely identify the activity of molecule in cancer cell. The electronic charge distribution of these different compounds is further illustrated by UV-Vis spectroscopy in the frequency range 190-1100 nm. The theoretical results obtained from molecular modeling calculations showed that the hydrogen bonds between the OH, CO, NH, and/or CH groups vary from one compound to the other regarding their number and bond length. This confirms the experimental FTIR results regarding the position and broadening of the OH and NH groups due to free rotation of the amide group because of changing the compounds structure by adding different groups to the last phenyl ring. The hydrogen bonds take different directions and values from one compound to the other, which seems to be the most important factor regarding the activity of these different compounds in cancer cell. Both theoretical molecular modeling calculations and FTIR experimental results have strongly evaluated the relation between the chemical structure of 5-chloro-N (4-sulfamoylbenzyl) salicylamide derivatives and their biological activities.

Terahertz and infrared reflectivity measurements were carried out on monoclinic vanadium oxide VO2 prepared directly in nanoscale by hydrothermal technique. The product was annealed in argon atmosphere at pressure 100 Pa for 6 h at temperatures 350 degrees C, 450 degrees C and 550 degrees C. The as-grown and annealed samples were investigated by XRD, HRTEM, VSM, DSC, THz, and FTIR techniques to explore the effect of annealing on the optical and electronic properties. The obtained results reveal the existence of monoclinic M-B-VO2 phase for the as-grown sample, while the annealed samples include two other oxidation phases V6O13 and V2O5 together with the monoclinic VO2 phase. This observation is supported by the data obtained from XRD, VSM, and DSC measurements. Both THz transmittance and infrared reflectivity measurements performed at room temperature show insulating behavior for the as-grown monoclinic VO2 sample whereas subtle modifications of monoclinic VO2 phase by annealing induces a metallic behavior via enhancement of surface area to volume ratio and increasing the grain boundaries as a result of embedded and distributed of two other phases V6O13 and V2O5 within the monoclinic VO2 matrix. Fitting of the optical conductivity deduced from both THz and infrared measurements clearly shows Drude-like behavior for the annealed sample while this behavior was not observed in case of the as-grown sample.

We present the preparation of highly conducting, transparent, and flexible reduced graphene oxide/silver nanowires (rGO/SNWs) substrates using non-thermal laser photoreduction method. High quality mono layers graphene oxide (GO) solution has been prepared by the chemical oxidation of thermally expanded large area natural graphite. Silver nanowires was prepared by using the typical polyol method. Uniform hybrid GO/silver nanowires (GO/SNWs) was prepared by growing the nanowires from silver nuclei in the presence of GO. Uniform and high-quality rGO/SNWs thin films were prepared using a dip-coating technique and were reduced to highly electrically conductive graphene and transparent conductive films using non-thermal laser scribe method. The laser scribed rGO/SNWs hybrid film exhibited 80% transparency with 70 Omega square(-1) after 20 min of dipping in GO/SNWs solution. (C) 2018 Elsevier Ltd. All rights reserved.

We present terahertz spectroscopy study on spherical nanoparticles powder mixture of aluminum, alumina, and MWCNTs induced by surface mechanical attrition treatment (SMAT) of aluminum substrates. Surface alloying of AL, Al2O3 0.95% and MWCNTs 0.05% powder mixture was produced during SMAT process, where a compact surface layer of about 200 μm due to ball bombardment was produced from the mixture. Al2O3 alumina powder played a significant role in MWCNTs distribution on surface, those were held in deformation surface cites of micro-cavities due to SMAT process of Al. The benefits are the effects on resulted optical properties of the surface studied at the terahertz frequency range due to electrical isolation confinement effects and electronic resonance disturbances exerted on Al electronic resonance at the same range of frequencies. THz acoustic phonon around 0.53-0.6THz (17-20cm-1) were observed at ambient conditions for the spherical nanoparticles powder mixture of Al, Al2O3 and MWCNTs. These results suggested that the presence of Al2O3 and MWCNTs during SMAT process leads to the optically detection of such acoustic phonon in the THz frequency range.