Internal Polymerization of Epoxy Group of Epoxidized Natural Rubber by Ferric Chloride and Formation of Strong Network Structure

In this work, studies are carried out to understand the crosslinking reaction of epoxidized natural rubber (50 mol% epoxy, ENR-50) by metal ion namely ferric ion (Fe3+, FeCl3, ferric chloride). It is found that a small amount of FeCl3 can cure ENR to a considerable extent. A direct interaction of the ferric ion with the epoxy group as well as internal polymerization enable the ENR to be cured in an efficient manner. It was also found that with the increased concentration of FeCl3, the crosslinking density of the matrix increased and therefore, the ENR offers higher mechanical properties (i.e., modulus and tensile strength). In addition, the glass transition temperature (tg) of ENR vulcanizate is increased with increasing concentration of FeCl3. Moreover, the thermal degradation temperature (Td) of the ENR-FeCl3 compound was shifted toward higher temperature as increasing concentration FeCl3.

Comparative Study of the Antioxidant Activity of Holarrhena Floribunda and Picralima Nitida

Picralima nitida (Stapf) T.Durand & H.Durand and Holarrhena floribunda (G.Don) T.Durand & Schinz are West and Central African plant species belonging to the Apocynaceae family. These two plants are used in traditional Ivorian medicine to treat hypertension, urinary tract infections, diarrhea, gonorrhea, malaria and diabetes. Phytochemical screening and evaluation of antioxidant activity of P. nitida fruit and H. floribunda leaf extracts of each of these two species have already been performed. In the present study, a comparative evaluation of the antioxidant activity of fruit (P. nitida) and leaf (H. floribunda) decoctions was carried out. The decoctions of P. nitida fruits and H. floribunda leaves were rich in secondary metabolites, especially polyphenols which have good antioxidant activity. Quantification of total phenols and flavonoids gave respective values of QP = 15235.632 ± 622 µg GAE / g dry matter and FP = 2.387 ± 0.387% for P. nitida and QH = 68597.701 ± 3171 µg GAE / g dry matter and FH = 17.581 ± 0.379% for H. floribunda. P. nitida showed antioxidant activity against DPPH radical (IC50 = 104.30 ± 3.17 μg / mL) and ferric ion Fe3 + (261.4 ± 36. 87 μmoL Eq Trolox / g extract). H. floribunda showed antioxidant activity against DPPH radical (IC50 = 41.73 ± 0.29 μg / mL) and ferric ion Fe3 + (365 ± 20.36 μmol Eq Trolox / g ExS).

Synthesis, Biological Activity of Trimethoprim derivative and the Complexes

This study demonstrates the synthesis of new ligands derived from trimethoprim with their Iron(III) and copper (ll) complexes. At the beginning, preparing new ligands, the first namly N, N’-(5-(3,4,5-trimethoxybenzyl)pyrimidine-2,4-diyl)bis(3,4,5-trihydroxy benza mide)and the Ligand second namly N, N’-(((5-(3,4,5-trimethoxybenzyl)pyrimidine-2,4-diyl) bis(azanediyl))bis(carbonthioyl) bis(3,4,5-trihydroxybenzamide) which prepared by nucleophilic addition of trimethoprim to Gallic chloride and prepared also by nucleophilic addition of trimethoprim to the Solution of Ammonium thiocyanate and Gallic chloride. Ferric Ion (III) and Copperic Ion (ll) complexes have been prepared with molar ratio [1:2]. The synthesis ligands have been characterized by Uv-Visible, FT-IR, 1HNMR, 13CNMR and EI-mass, while the complexes have been characterized by elemental analysis, Uv-Visible, FT-IR, Conductivity measurements and thermogravemtric (TgA) analysis. The ligands acts as multiple sites coordinating with ferric ion and copper ion, Via lone pair of nitrogen atom of NHC= and phenolic oxygen. In Vitro, the ligands and complexes have been tested for their growth Inhibitory activity against Gram negative bacteria Salmonella Spp and Gram Positive Staphylococcus Spp. The results of the test indicate that the synthesized compounds possessed a high inhibition effectiveness comparative with trimethoprim.

Water Pollution Control and Treatment Based on Quantum Dot Chemical and Biological High-Sensitivity Sensing

Inorganic pollutants in water can have an important impact on ecosystems and human health, so the development of rapid and sensitive detection methods for typical inorganic pollutants in water samples is important for understanding the pollution status of the water environment, as well as water pollution prevention and protection of drinking water safety. Fluorescence sensing technology has the advantages of fast response, high sensitivity, simple operation, and low cost but still has the problems of low quantum yield, cumbersome construction process, and limited practical applications. Based on the excellent fluorescence properties, a series of fluorescence sensing was constructed for the rapid, highly sensitive, and selective detection of various typical inorganic pollutants in water. And the related fluorescence sensing mechanism was investigated in this paper. In this paper, nitrogen/sulfur codoped carbon quantum dots (N, S-CQDs) were prepared for the sensitive and selective detection of sulfide and ferric ion. The blue fluorescent N, S-CQDs were prepared by a one-step hydrothermal method using ammonium citrate and L-cysteine as raw materials, which have excitation wavelength dependence and fluorescence quantum yield of 16.1% for the selective detection of sulfides with a detection limit ( S / N = 3 ) of 11.0 nM (about 0.35 μg/L). CQDs with significantly higher fluorescence quantum yields (69%) and no excitation dependence were prepared when citric acid was used instead of ammonium citrate and were used for the selective detection of ferric ion with a detection limit of 14.0 nM (~0.8 μg/L). The method has been successfully applied to the determination of total phosphorus in surface water and human urine, and the fluorescence color change of the dual-emission sensing can be used for the naked-eye identification and semiquantitative detection of phosphate.

Determination of the Phenolic Content in Iranian Trehala Manna and Evaluation of Their Antioxidant Effects

One of the most challenging issues in the food and pharmaceutical industries is finding effective and safe antioxidants from natural resources compared to their synthetic compounds, which have side effects. In this regard, Trehala manna was considered a great antioxidant source categorized as the major type of manna produced naturally and by the Echinops plant in response to insect activity. In this study, the antioxidant activity and phenolic content of the numerous Trehala manna in Echinops sp. have been investigated. Different methods of radical scavenging activity comprising 2,2′-azino-bis (3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) and 2, 2-diphenyl-1-picrylhydrazyl (DPPH) have been investigated to evaluate antioxidant activity. The phenolic contents were measured by Folin–Ciocalteu and standard phytochemical methods. Quantitative and qualitative amounts of phenolic content, including caffeic, ferulic, coumaric, syringic, and hydroxybenzoic acids, were quantified by high-performance liquid chromatography (HPLC). The results indicated the significant changes in the amounts of phenolics and the antioxidant properties in Trehala manna samples, based on the place of collection. Based on results, antioxidant capacity detected by DPPH and ABTS tests showed the IC50 values of 40–94 µg/mL and 28–72 µg/mL, respectively. Results of the FRAP test represented very strong ferric ion reducing activities (0.04–0.83 mmol Fe2+/g). Ferric ion reducing data were not markedly different from ABTS and DPPH ones. These samples also presented the highest phenolic content (1.32–2.28 mg GAE/100 g). Jahrom Trehala manna was the highest in both phenolic content and antioxidant value, while Sabzevar was the lowest. We found a significant relationship between the antioxidant values and total phenolic counts. It indicates that the phenolics contribute to the observed antioxidant activities of these samples.