Influence type of natural rubber on properties of green biodegradable thermoplastic natural rubber based on poly(butylene succinate)

Green biodegradable thermoplastic natural rubber (GB‐TPNR) based on simple blend of natural rubber (NR) and poly(butylene succinate) (PBS) was prepared using three NR alternatives: unmodified NR and epoxidized NR with 25‐ or 50‐mol% epoxide (ie, ENR‐25 or ENR‐50). It was found that ENR‐50/PBS blend showed the best compatibility, which resulted in superior mechanical and thermal properties with the highest crystallinity of the PBS phase, on comparing with the ENR‐25/PBS and NR/PBS blends. This might be attributed to stronger chemical interactions between the epoxide groups in ENR‐50 and the polar functional groups in PBS, which were confirmed by Fourier transform infrared (FTIR). Furthermore, scanning electron microscopy (SEM), atomic force microscopy (AFM), and polarizing optical microscopy (POM) micrographs of ENR‐50/PBS blend revealed phase separation with finer‐grained cocontinuous structure than in ENR‐25/PBS and NR/PBS simple blends. Furthermore, the chemical interactions in ENR‐50/PBS blend enhanced the resistance to accelerated weathering.     

Green synthesis and chemical characterization of silver nanoparticles obtained using Allium saralicum aqueous extract and survey of in vitro antioxidant,cytotoxic, antibacterial and antifungal properties

Allium saralicum R.M. Fritsch has been used in Iranian traditional medicine as a remedial supplement for microbial diseases. This paper reports the green synthesis, chemical characterization and antioxidant, cytotoxic, antibacterial and antifungal properties of silver nanoparticles obtained using aqueous extract of A. saralicum leaves. In this synthesis, no surfactants or stabilizers were used. For characterization, UV–visible spectroscopy, transmission electron microscopy, X‐ray diffraction, energy‐dispersive X‐ray spectroscopy and field emission scanning electron microscopy were used. 2,2‐Diphenyl‐1‐picrylhydrazyl was used in experiments to assess the antioxidant potential of the silver nanoparticles, which revealed an impressive prevention in comparison with butylated hydroxytoluene. The synthesized silver nanoparticles at low doses (1–250 μg dl^?1) did not show marked cytotoxic activity (against cervical cancer cells (Hela), breast cancer cells (MCF‐7) and human embryonic kidney cells (HEK‐293)). Agar diffusion tests were applied to determine the antibacterial and antifungal characteristics. Compared with all standard antimicrobials, the silver nanoparticles showed higher antibacterial and antifungal activities (p ≤ 0.01). Also, the silver nanoparticles inhibited the growth of all bacteria and fungi at concentrations of 31–250 μg ml^?1, and destroyed them at concentrations of 31–500 μg ml^?1 (p ≤ 0.01). Because the silver nanoparticles obtained using aqueous extract of A. saralicum leaves have antioxidant, non‐cytotoxic, antifungal and antibacterial potentials, they can be used as a medical supplement or drug.     

Easy conversion of nitrogen‐rich silk cocoon biomass to magnetic nitrogen‐doped carbon nanomaterial for supporting of Palladium and its application

In this study, magnetic nitrogen‐doped carbon (MNC) was fabricated through facile carbonization and activation of natural silk cocoons containing nitrogen and then combined with Fe₃O₄ nanoparticles to create a good support material for palladium. Palladium immobilization on the support resulted in the formation of magnetic nitrogen‐doped carbon‐Pd (MNC‐Pd). The prepared heterogeneous catalyst was well characterized using FT‐IR, TGA, EDX, FE‐SEM, XRD, VSM, and ICP‐OES techniques. Thereafter, the synthesis of biaryl compounds was conducted to investigate the catalyst performance via the reaction of aryl halides and phenylboronic acid. Further, the catalyst could be used and recycled for six consecutive runs without any significant loss in its activity.     

Synthesis and photocatalytic activity assessing of the TiO<Subscript>2</Subscript> nanocomposites modified by some lanthanide ions and tin-derivative sandwich-type polyoxometalates

New nanocomposites containing sandwich-type polyoxometalate of [(PW₉O₃₄)₂(HOSn^IVOH)₃]^12? (P₂W₁₈Sn₃) loaded onto Ln-doped TiO₂ (Nd, Sm, Dy, Tb) nanoparticles were synthesized and their catalytic activities were assessed. The Ln–TiO₂ nanoparticles and Ln–TiO₂/P₂W₁₈Sn₃ nanocomposites were characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction, field emission scanning electron microscope, energy dispersive analysis of X-rays spectra and diffuse reflectance spectra. The photocatalytic efficiency of the Ln–TiO₂ and Ln–TiO₂/P₂W₁₈Sn₃ were examined in the photodegradation of methyl orange and methylene blue solutions. It was revealed through different characterization techniques that the P₂W₁₈Sn₃ was successfully loaded on the lanthanide-doped anatase phase TiO₂ nanoparticles and the particles diameter were relatively 20–30 nanometers. It was revealed that doping by the lanthanide ions followed by loading of polyoxometalates improves the photocatalytic performance of TiO₂ effectively. The effects of operational parameters and the kinetics of photocatalytic degradation under UV light were discussed. The prepared nanocomposites were stable and could be easily separated from the reaction system.     

Dynamic stereochemistry of erigeroside by measurement of 1H-1H and 13C-1H coupling constants

Erigeroside was extracted from Satureja khuzistanica Jamzad (Marzeh Khuzistani in Persian, family of lamiaceae), and (1)H, (13)C, (13)C{(1)H}, (1)H-(1)H COSY, HMQC and J-HMBC were obtained to identify this compound and determine a complete set of J-coupling constants ((1)J(C-H), (2)J(C-H), (3)J(C-H) and (3)J(H-H)) values within the exocyclic hydroxymethyl group (CH(2)OH) and anomeric center. In parallel, density functional theory (DFT) using B3LYP functional and split-valance 6-311++G** basis set has been used to optimized the structures and conformers of erigeroside. In all calculations solvent effects were considered using a polarized continuum (overlapping spheres) model (PCM). The dependencies of (1)J, (2)J and (3)J involving (1)H and (13)C on the C(5')-C(6') (omega), C(6')-O(6') (theta) and C(1')-O(1') (phi) torsion angles in erigeroside were computed using DFT method. Complete hyper surfaces for (1)J(C1',H1'), (2)J(C5',H6'R), (2)J(C5',H6'S), (2)J(C6',H5'), (3)J(C4',H6'R), (3)J(C4',H6'S) and (2)J(H6'R-H5'S) as well as (3)J(H5',H6'R) were obtained and used to derive Karplus equations to correlate these couplings to omega, theta and phi. These calculated J-couplings are in agreement with experimental values. These results confirm the reliability of DFT calculated coupling constants in aqueous solution.     

DFT and TD-DFT study of benzene and borazines containing chromophores for DSSC materials

In this investigation, we have designed a series of benzene and borazines containing chromophores for employing in dye-sensitized solar cells (DSSCs). The optimized structures and photo-physical properties of these molecules have been explored by using the density functional theory method (B3LYP/6-311++G(d,p)). These dyes consist of electron-donor (benzene, borazine, fluorinated borazine) and -acceptor/anchoring (tricyanovinyl), connected by the π-conjugated linker as an electron spacer. The Natural Bond Orbital (NBO) analysis has also been employed for studying the origin of charge transfer. The time-dependent density functional theory (TD-DFT) method has also been used to calculate the electronic absorption spectra of these molecules. The maximum absorption wavelengths assign to HOMO → LUMO transition. The electronic coupling constant, electron injection and light harvesting efficiency have been computed by first principle researches. This revealed that the studied molecules would be efficient photosensitizers.     

Oxidation of oleic acid and oleic acid/sodium chloride(aq) mixture droplets with ozone: changes of hygroscopicity and role of secondary reactions

The heterogeneous reactions of oleic acid (OL) and oleic-acid/sodium-chloride(aq) (OL/NaCl(aq)) mixture droplets with ozone are studied at two relative humidities (RH). The reactions were monitored concomitantly using attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FT-IR) for the organic species and UV-vis spectrometry for the ozone concentration in order to investigate reaction rate discrepancies reported in literature as well as the oxidation mechanism. The less volatile products were identified and resolved by a Fourier transform ion cyclotron resonance mass spectrometer (FT-ICR-MS). This led to identification of 13 organic molecules (up to 45 carbons). Identified products were predominantly composed by nananoic acid and azelaic acid. Our results suggest that the propagation reaction is possibly initiated by a secondary reaction such as the stabilized Criegee intermediates reacting with oleic acid. For hygroscopic properties, the ATR-IR spectra at high RH (87 +/- 5%) showed that the hydrophobic oleic acid droplets can take up water slightly when exposed to ozone. For internally mixed OL/NaCl(aq) droplets, the hygroscopic properties of the droplets upon ozone exposure were found to be complex; hygroscopic properties or the growth factors of the droplets are altered as the oxidation products of oleic acid exist concurrently with NaCl(aq). Furthermore, the concentration of ozone was monitored to examine the kinetics of the oxidation reaction. The integrated ozone profile recorded by UV-vis spectrometry showed the consumed ozone represents only 30 +/- 2% of total oleic acid and hence confirmed the existence of secondary reactions. A kinetic model was used to simulate an ozone temporal profile that could only be described if the secondary reactions were included. The discrepancy of ozone uptake coefficients according to the OL and ozone measurements as well as their atmospheric implications are herein discussed.