The synthesis,structure and spectroscopic properties of novel oxazolone-, pyrazolone- and pyrazoline-containing heterocycle chromophores

A series of novel heterocycle-based chromophores containing oxazolone, pyrazolone or pyrazoline moieties were synthesized under microwave irradiation and characterized using elemental analysis, IR, ¹H NMR spectroscopy and mass spectrometry. The crystal structures of two of the dyes were found, using single crystal X-ray crystallography, to be monoclinic, space group P2₁/c types; the two molecules adopted a Z configuration about the central olefinic bond. The heterocyclic chromophores were fluorescent, with some examples emitting blue light (410–460 nm) whilst others emitted green light (529 nm). The absorption maxima of the chromophores were found to vary from 349 to 463 nm depending on the extent of conjugation.     

The microwave-assisted synthesis and characterization of novel metal-free and metallophthalocyanines peripherally fused to four 13-membered diazadithia macrocycles

The novel tetrasubstituted metal-free phthalocyanine and metallophthalocyanines 7, bearing four 13-membered diazadithia macrocycle moieties at peripheral positions were synthesized by cyclotetramerization of the corresponding phthalonitrile derivative in a multi-step reaction sequence. The metal-free phthalocyanine was synthesized by microwave irradiation of the corresponding dicyano compound in 2-(dimethylamino)ethanol for 10 min. Metallophthalocyanines were obtained from the respective dicyano derivative and corresponding anhydrous metal salts NiCl₂ and ZnCl₂, CoCl₂, CuCl₂, respectively, by microwave irradiation in 2-(dimethylamino)ethanol at 175 °C, 350 W for 10 min. The new compounds were characterized by a combination of IR, ¹H NMR, ¹³C NMR, UV–vis, elemental analysis and MS spectral data.     

A hybrid microreactor/microwave high-pressure flow system of a novel concept design and its application to the synthesis of silver nanoparticles

This article reports on a microreactor/microwave high-pressure flow hybrid apparatus of a novel concept design, which includes both the microreactor and a spiral reactor, and its efficient use in the synthesis of silver nanoparticles of relatively uniform sizes (4.3 ± 0.7 nm) under microwave irradiation. By contrast, under otherwise identical experimental conditions but with conventional heating, the nanoparticle size was non-uniform (8.3 ± 2.7 nm) and the spiral reactor walls were covered with a silver mirror deposit. Formation of the nanoparticles was monitored by UV–visible spectroscopy (plasmonic absorption band; LSPR), TEM and by small-angle X-ray scattering (SAXS). Both the spiral microreactor and the spiral quartz reactor of the hybrid system played an important role in the synthesis, with the microreactor providing the environment wherein mixing of the aqueous solution of [Ag(NH₃)₂]⁺ and the solution of glucose (the reducing agent) and poly(N-vinyl-2-pyrrolidone) (PVP; stabilizer/dispersing agent) occurred. The microwaves provided the thermal energy to effect a uniform growth of the silver nanoparticles at temperatures above 120 °C. Mixing the two solutions by conventional methods (no microreactor) failed to yield such nanoparticles even under microwave irradiation and no formation of a silver mirror occurred in the inner walls of the spiral reactor.     

New azo ligands containing azomethine groups in the pyridazine-based chain: Synthesis and characterization

Five, novel pyridazine-based azo chromophores were synthesized by the condensation reaction of 3,6-bis((aminoethyl)thio)pyridazine with 5-(4-X-phenyl)-azo-salicylaldehyde (X = NO₂, Cl and Et), 5-(2,4-di-Cl-phenyl)-azo-salicylaldehyde and 5-(3,4-di-Cl-phenyl)-azo-salicylaldehyde. The dyes were characterized by elemental analysis, thermal analyses, IR, UV–vis, NMR and mass spectroscopy. Spectral characteristics of the dyes were investigated in four organic solvents of differing polarity; thermal studies indicate that the framework of dyes is stable up to 220 °C. Complexation of the azo dyes with Cu(II) gave subtle changes in their absorption spectra.     

Charge transport properties of single crystal CVD-diamond particle detectors

The charge transport properties of virgin and heavily irradiated intrinsic Single-Crystal CVD-Diamond Detectors (SC-CVD-DD) are discussed by means of the Transient-Current Technique (TCT), which proved to be a sensitive tool to detect the first changes of the detector's performance. Charge-carrier mobilities μ_e = 1300–3100 cm²/V s, μ_h = 2400 cm²/V s and effective deep-trapping lifetimes τ_eff-h = 300–900 ns, τ_eff-e = 160–360 ns were measured in the non-irradiated state, decreasing slightly after irradiation by a fluency F > 10¹³ p_26MeV cm^− 2. The carriers drift velocity remained almost unchanged after irradiation, indicating the creation of mainly neutral defects. After exposure to fluency above 10¹⁶ p cm^− 2 however, TC signals were not detectable with the available broadband electronics. A significant improvement was observed after annealing at 1000 °C, and almost complete restoration was obtained by priming with ⁹⁰Sr-electrons. Optical absorption (OA) spectra confirmed the degradation of the detector performance after exposure to increasing particle fluencies, showing deviations from the intrinsic ‘edge absorption’ shape around 5.3 eV that was observed before irradiation.     

Correlation between infrared,THz and microwave dielectric properties of vanadium doped antiferroelectric BiNbO4

Terahertz (THz) transmissivity and infrared (IR) reflectivity spectra of orthorhombic microwave (MW) ceramics Bi(Nb_1−xV_x)O₄ (0.002 < x < 0.032) were measured between 4 and 3000 cm⁻¹ (0.09–90 THz) at room temperature. A well underdamped mode, presumably the ferroelectric soft mode, was observed at 25 cm⁻¹. Complex permittivity spectra obtained from the fits to our data were extrapolated down to the MW range and compared with the dielectric data near 5 GHz. The linear extrapolation of dielectric losses from THz down to the MW range is in agreement with the experimental MW losses. Addition of 3.2% of vanadium reduces the sintering temperature to 850 °C and the dielectric properties (ɛ′ = 42.2, Q·f = 14,000 GHz, τ_f = +10 ppm/°C) remain at a level satisfactory for MW applications. Somewhat lower MW losses were observed in a sample sintered in the N₂ atmosphere.     

Neutron transmutation of 10B doped diamond

Free standing ¹⁰B isotope doped diamond films deposited by chemical vapor deposition in a microwave chamber were irradiated to thermal neutron fluence values of 0.32 × 10¹⁹, 0.65 × 10¹⁹, 1.3 × 10¹⁹, and 2.6 × 10¹⁹ n/cm². Cooling of the diamond films was maintained during irradiation. In a separate experiment, neutron irradiation to a total fluence of 2.4 × 10²⁰ n/cm² with equal fast and thermal neutrons was also performed on a diamond epilayer without cooling during irradiation. The formation of defects in the diamond films was characterized using Raman, FTIR, photoluminescence, electron paramagnetic resonance spectroscopy, and X-ray diffraction. It was found that defect configurations in diamond responsible for an increase in continuum background in the one-phonon region of Raman spectrum were absent in the films that have been cooled. The FTIR peak at 1530 cm^− 1 annealed in the sample irradiated to a fluence of 2.6 × 10¹⁹ n/cm² indicating that the sample reached a temperature of 300 °C during irradiation. Absence of characteristic infrared absorption peaks that were observed only upon annealing neutron irradiated diamond is used to conclude that the temperature of the sample during neutron irradiation to a fluence of 2.6 × 10¹⁹ n/cm² was well below 650 °C needed for mobility of defects and accumulation of stable unrecoverable damage. On the other hand, results from diamond epilayer subjected to equal thermal and fast neutron fluence of 2.4 × 10²⁰ n/cm² and without cooling showed that defects formed from displaced carbon atoms became mobile and formed complex configurations of irrecoverable damage. Electrical conductance of the unirradiated and irradiated diamond samples was measured as a function of temperature to determine the compensation of the p-type by the n-type charge carriers.     

Effects of microwave irradiation on concentration,diversity and gene mutation of culturable airborne microorganisms of inhalable sizes in different environments

Previously, we have investigated the inactivation of total environmental bioaerosols using microwave irradiation at 2450 MHz. Here, the effects of microwave irradiation on the concentration, diversity and possible gene mutations of airborne culturable microorganisms of different size ranges were investigated. Air samples were collected in different environments (office, hotel and outdoor) using a six-stage Andersen sampler operated at its standard flow rate of 28.3 L/min without and with the microwave irradiation at three different power levels(119, 385 and 700 W) corresponding to energy doses of 7.1, 22 and 31.5 kJ, respectively. For each experimental condition, three to five independent replicates were conducted. Air samples collected onto different stages of the Andersen sampler were incubated at 26 °C, and colony forming units (CFUs) were manually counted and statistically corrected. The bacterial CFUs were further washed off from agar plates using deionized water, and subjected to polymerase chain reaction (PCR)-denaturing gradient gel electrophoresis (DGGE) for diversity and possible gene mutation analysis.Results revealed that for the outdoor environment, larger size (>3.3 μm) bacterial species dominated, while for the indoor environments those of smaller size (<2.1 μm) did. Use of the high power level (700 W) in general resulted in lower culturable bacterial counts regardless of the sampler stage and the sampling environment. The inactivation efficiencies of the microwave treatment were shown to strongly depend on the environments and the microwave energy dose under the experimental conditions tested. PCR-DGGE analysis indicated that use of the high power microwave irradiation (31.5 kJ) generally resulted in less culturable bacterial aerosol richness, while for medium (22 kJ) and low (7.1 kJ) energy doses their culturable species richness appeared to be similar to those of the control experiments. In contrast, smaller (1.1–2.2 μm) culturable fungal species were found to dominate regardless of sampling environments. In addition, culturable bacterial aerosol gene mutations with a high frequency after the microwave treatment were detected in the colonies developed. The results from this study provide further information in developing microwave-based bioaerosol inactivation technology.     

Removal of trace boron from aqueous solution using iminobis-(propylene glycol) modified chitosan beads

In this paper, a new boron chelating chitosan based polymer with multi-hydroxyl iminobis (propylene glycol) (IBPG) functions was prepared. A cross-linked chitosan (CCTS) with 2.70 mmol g⁻¹ amine content was modified with excess amount of glycidol at pH 7 and boron chelating resin with IBPG functions (4.60 mmol g⁻¹) was obtained. The boron chelating ability of the resulting resin was investigated under different experimental conditions (pH, foreign ions). This prepared material was evaluated by FT–IR spectra and UV spectra analysis. The IBPG modified CCTS resin was demonstrated to have a boron loading capacity of 2.2 ± 0.05 mmol g⁻¹ within 45 min. Desorption and resin regeneration studies were carried out to determine the effectiveness of the synthesized resin with HCl and NaOH respectively. The adsorption test indicated that the chitosan based chelating resin with IBPG functions exhibited higher selectivity of boron (2.05 mmol g⁻¹) in the presence of foreign ions especially Fe(III).     

Infrared-transparent films based on conductive graphene network fabrics for electromagnetic shielding

Transparency in the infrared (IR) light region and high conductivity for electromagnetic (EM) shielding performance are contradicting properties for conventional window materials. It is challenging to explore a new class of materials with both IR transmittance and high electrical conductivity. Herein, middle-IR transmittance and EM-shielding performance are realized by graphene network fabrics (GNFs). GNFs are fabricated by chemical vapor deposition using copper mesh with different geometric constructions as the sacrificial substrate. The structure of GNFs endows the as-fabricated material high IR transmittance, good electrical conductivity, and EM-shielding efficiency. The grid parameter τ with regard to the square aperture and wire width exerts a profound effect on the EM-shielding performance. The highest EM-shielding efficiency is 12.86 dB at 10 GHz with a transmittance of 70.85% at 4500 nm. Meanwhile, the highest IR light transmittance is 87.85% with an EM-shielding efficiency of 4 dB. Based on the experimental and theoretical analyses, the EM-shielding efficiency is prominently dependent on microwave absorption.     

Generation of a low temperature NO linkage isomer in a transition metal complex of group 9: K[IrCl5NO]

The [IrCl₅NO]^− 1 ion in the potassium salt can be partially transformed into a metastable state by light irradiation in the violet-near UV region at low temperature (77 K). The excitation process was followed by infrared spectroscopy, comparing the spectra before and after irradiation.A new band grew at 1812 cm^− 1 after irradiation with light in the 308–420 nm spectral region. The metastable state behavior is verified as this band decays upon heating the samples above 90 K or by subsequent irradiation using 450–680 nm light. The band at 1812 cm^− 1 was assigned to ν(NO) of metastable state 1 (or an IrON linkage isomer) for comparison with the band position reported for other transition metal nitrosyls. To our knowledge, this is the first generation of a M-ON linkage isomer reported for a nitrosyl of transition metal of group 9. Its behavior is similar to that observed in other nitrosyl complexes of group 8.     

Effect of XeF laser treatment on structure of nanocrystalline diamond films

Nanocrystalline diamond (NCD) films were deposited on Si substrates by microwave plasma-enhanced chemical vapor deposition (MPECVD) using methane/hydrogen/oxygen (30/169/0.2 sccm) as process gases. Subsequently a thin (0.33 μm) and a thick (1.01 μm) NCD films were irradiated with XeF excimer laser (λ = 351 nm) with 300 and 600 mJ cm^? 2 of energy densities in air. The NCD films became rougher after laser irradiations. Fraction of graphitic clusters decreased but oxygen content increased in the thin NCD film after laser irradiation. Opposite phenomena were observed for the thick NCD films. Effect of laser irradiation to oxygenation and graphitization of NCD films was correlated with structural properties of free surface and grain boundaries of the thin and thick NCD films.     

Mechanism of diamond nucleation enhancement by electron emission via hot filament chemical vapor deposition

The mechanism of diamond nucleation enhancement by electron emission in the hot filament chemical vapor deposition process has been investigated by scanning electron microscopy, Raman spectroscopy and infrared (IR) absorption spectroscopy. The maximum value of the nucleation density was found to be 10¹¹ cm⁻² with a −300 V and 250 mA bias. The electron emission from the diamond coating on the electrode excites a plasma, and greatly increases the chemical species, as we have seen by in situ IR absorption. The experimental studies showed that the diamond and chemical species were transported and scattered from the diamond coating on the electrode and through the plasma towards the substrate surface, where they caused enhanced nucleation.     

Microwave-assisted and solvent-free peroxidative oxidation of 1-phenylethanol to acetophenone with a CuII–TEMPO catalytic system

The water-soluble copper(II) complex [Cu(H₂R)(HL)]∙H₂O (1) was prepared by reaction of copper(II) nitrate hydrate with (E)-2-(((1-hydroxynaphthalen-2-yl)methylene)amino) benzenesulfonic acid (H₂L) and diethanolamine (H₃R). It was characterized by IR and ESI-MS spectroscopies, elemental and X-ray crystal structural analyses. 1 shows a high catalytic activity for the solvent-free microwave (MW) assisted oxidation of 1-phenylethanol with tert-butylhydroperoxide, leading, in the presence of TEMPO, to yields up to 85% (TON = 850) in a remarkably short reaction time (15 min, with the corresponding TOF value of 3.40 × 10³ h^− 1) under low power (25 W) MW irradiation.     

Efficient hydrogen production by photocatalytic water-splitting using Pt-doped TiO2 hollow spheres under visible light

Pt doped TiO₂ hollow spheres (Pt/HS-TiO₂) are prepared by a sol–gel method and characterized by XRD, SEM, TEM and UV-visible absorption spectra. In addition, Pt/HS-TiO₂ is employed as the catalyst for photocatalytic hydrogen production from water splitting under visible light irradiation. The results show that Pt/HS-TiO₂ with hollow sphere structure presents excellent photocatalytic hydrogen evolution performance. The hydrogen generation rate can reach more than 1023.71 μmol h⁻¹ g⁻¹ at room temperature and no obvious deactivation is observed after 30 h irradiation. Furthermore, the reactively of Pt/HS-TiO₂ could be reproduced in the repeated cycle. Therefore, Pt/HS-TiO₂ is a promising photocatalyst to efficiently generate hydrogen under visible-light irradiation at room temperature.     

The effect of Ne+ ion implantation on polyimide film

The fluence of Ne⁺ ion irradiation on the surface modification of polyimide (Kapton HN type) film was investigated. The irradiation of ion implantation onto a polyimide film was performed, and the surface chemical structure was analyzed in detail by X-ray photoelectron spectroscopy (XPS). An acceleration voltage of 100 keV was used in the ion implantation with different doses from 5 × 10¹⁴ to 5 × 10¹⁷ ion cm^?2 and a beam current density of 10 μA cm^?2. The elemental ratios of carbon, oxygen and nitrogen were calculated from 1s peaks of the corresponding elements. The results showed that the content of carbon in the surface layer increased after ion irradiation, while the ratios of oxygen decreased after irradiation, especially in the case of the polyimide film treated at ion fluence. The O1s spectra after ion irradiation are related to the rearrangement of those recoil atoms and the ion incorporated into the film and the formation of new types of bond, such as C–O and O–O.     

Thin layer drying kinetics of Gundelia tournefortii L.

The literature surveyed revealed that the drying kinetics of Gundelia tournefortii has not been investigated. In this study, mathematical modeling of the thin layer drying kinetics of G. tournefortii is investigated for both the microwave and open sun drying conditions. Five different microwave power levels ranging from 90 to 800 W were used for the microwave drying. Solar radiation for the open sun drying varied from 350 to 1100 W/m². Drying took place in the falling rate period. Increasing the microwave power caused a significant decrease in drying time. The experimental moisture loss data were fitted to the 14 thin layer drying models. Among the models proposed, the Midilli model precisely represented the microwave drying behavior of G. tournefortii with the coefficient of determination higher than 0.996 and mean square of deviation (χ²), root mean square error (RMSE) and mean bias error (MBE) lower than 1.82 × 10^?4, 12 × 10^?3 and 1.4 × 10^?4, respectively for all the microwave drying conditions studied. Values of drying constant (k) were in the range of 0.0098–0.2943 min^?1 and the effective moisture diffusivities (D_eff) of G. tournefortii ranged from 5.5 × 10^?8 to 3.5 × 10^?7 m²/s. The values of k and D_eff increased with the increase of microwave power level. The logarithmic model was found to best describe the open sun drying kinetics of G. tournefortii. The effective diffusivity of G. tournefortii under the sun drying condition was determined as 2.48 × 10^?10 m²/s.     

Sunlight photodecolorization of a mixture of Methyl Orange and Bromocresol Green by CuS incorporated in a clinoptilolite zeolite as a heterogeneous catalyst

Photocatalytic activity of CuS incorporated into an Iranian clinoptilolite (CuS-Cp) was studied for decolorization of a mixture of Methyl Orange and Bromocresol Green under sunlight irradiation. All samples were characterized by XRD, FTIR, DRS and TG/DTG techniques. The effect of some key experimental parameters such as: amount of the catalyst (0.05–5 g L^?1), initial concentration of dyes (5–30 mg L^?1), solution pH (1–11) and also dosage of H₂O₂ and KBrO₃ was studied on the decolorization extent. The extent of decolorization was estimated from the residual concentration by spectrophotometrically and it was confirmed by the reduction of chemical oxygen demand (COD).     

Synthesis,DNA-binding and antioxidant activity studies of naphthoxazole compounds

Four new naphthoxazole compounds 1–4 have been synthesized and characterized. The DNA-binding was studied by absorption spectroscopy, viscosity measurements and luminescence spectra. The DNA binding constants were determined to be 5.06 × 10³ for 1, 5.29 × 10⁴ for 2, 3.58 × 10³ for 3 and 7.75 × 10³ M^− 1 for 4, respectively. The results show that these compounds can intercalate into the DNA base pairs. The stoichiometries of compound/DNA are 1:1 for 1, 2, 4, and 1.5:1 for 3. Interaction of compounds 1–4 with plasmid pBR322 DNA studied by gel electrophoresis experiments reveals that compounds can cleave pBR322 DNA upon irradiation or hydrolytic conditions. The antioxidant activities of these compounds against hydroxyl radical were also explored.     

Fabrication of fluorine-terminated diamond-like carbon thin film using a hyperthermal atomic fluorine beam

Surface modification of diamond-like carbon (DLC) film was performed using a hyperthermal atomic fluorine beam on the purpose of production of hydrophobic surface by maintaining the high hardness of DLC film. By the irradiation of atomic fluorine beam of a 1.0 × 10²⁰ atoms/cm², the contact angle of a water drop against the DLC surface increased from 73° to 111°. The formation of CF₃, CF₂ and CF bonding on the modified DLC surface was confirmed from the measurements of X-ray photoelectron spectra and near-edge X-ray absorption fine structure spectra. Irradiation of hyperthermal atomic fluorine beam was concluded to produce insulator fluorine-terminated DLC film, which has high F content on the surface, by the taking of the use of neutral atomic beam as a fluorine source.