Evaluation of chemical constitute,fatty acids and antioxidant activity of the fruit and seed of sea buckthorn (Hippophae rhamnoides L.) grown wild in Iran

In this investigation, the chemical compositions of berries from sea buckthorn were studied. The amount of ascorbic acid and β-carotene determined by HPLC was 170 mg/100 g FW and 0.20 mg/g FW, respectively. Total phenols, anthocyanins, acidity and total soluble solids (TSS) contents were 247 mg GAE/100 g FW, 3 mg/L (cyanidin-3-glucoside), 5.32% and 13.8%, respectively. Fruit antioxidant activity determined by the ferric reducing ability of plasma (FRAP) method was 24.85 mM Fe/100 g FW. Results confirmed the presence of six dominant fatty acids (determined by GC) in fruit including linoleic (34.2%), palmitoleic (21.37%), palmitic (17.2%), oleic (12.8%), linolenic (5.37%) and stearic acid (1.67%). Five dominant fatty acids of the seeds were linoleic (42.36%), linolenic (21.27%), oleic (21.34%), palmitic (6.54%) and stearic acid (2.54%). The nitrogen content was 3.96%. The P, K, Ca, Mg, Fe, Zn, Mn, Cu, Cd and Cl contents of fruit were 491, 1674, 1290, 990, 291, 29.77, 108.37, 17.87, 0.021 and 2.18 mg/kg DW, respectively.     

Sensing and catalytic decomposition of hydrogen peroxide by silicon carbide nanotubes: A DFT study

In this study, by carrying out detailed density functional theory calculations, we investigate the adsorption and stepwise decomposition of hydrogen peroxide (H₂O₂) over (6,0) and (7,0) zigzag silicon carbide nanotubes (SiCNTs). The results indicate that the H₂O₂ can be adsorbed on the exterior surface of the SiCNTs with noticeable adsorption energies and charge transfers. To gain insight into the catalytic activity of the surface, the interaction between the H₂O₂ and SiCNT is analyzed by detailed electronic analysis such as adsorption energy, charge density difference and activation barrier. The decomposition of H₂O₂ into O₂ and H₂ species can be viewed as the kinetically preferred reaction pathway for dehydrogenation of hydrogen peroxide over SiCNTs. There is also a curvature effect on the dehydrogenation kinetics of hydrogen peroxide, that small diameter SiCNTs with large curvature would be beneficial for decomposition of H₂O₂. © 2015 Wiley Periodicals, Inc.     

肽纳米纤维固载Pd纳米颗粒为催化剂、羟基苯并三唑为新型苯基化试剂合成联芳

研究了肽纳米纤维负载的Pd纳米颗粒催化卤代芳烃与羟基苯并三唑的直接偶合反应.结果表明,该偶合反应可在简单、绿色及温和的条件下进行,并可以较高产率生成相应的联芳.本文首次采用羟基苯并三唑作为苯基化试剂,且将肽纳米纤维作为一种新型可循环使用的载体,因而对现有合成方法是一个有益补充.     

Co3O4 nanoparticles prepared by oxidative precipitation method: an efficient and reusable heterogeneous catalyst for N-formylation of amines

Research on Chemical Intermediates - N-formylation of different amines was carried out with formic acid in the presence of the Co3O4 nanoparticles as an efficient, stable heterogeneous catalyst to...     

Study of structural,electrical and dielectric behavior of cadmium selenide quantum dots/polyaniline nanocomposites

In this study, the cadmium selenide quantum dots/polyaniline nanocomposites were prepared by in-situ polymerization technique and they were characterized using X-ray diffraction and Fourier transform infrared spectroscopy. The surface morphology was studied by scanning electron microscopy. The electrical and dielectric properties were investigated by using 4-probe mechanism and LCR meter respectively. The increase in dielectric constant was observed with the increase of quantum dots content in the nanocomposites. The frequency dependent AC conductivity followed the universal power law. The temperature dependent DC conductivity was found to be a typical for a semiconducting behavior following Mott’s 1D variable range hoping model.     

Unlocking the Secrets of Cancer Stem Cells with γ-Secretase Inhibitors: A Novel Anticancer Strategy

The dysregulation of Notch signaling is associated with a wide variety of different human cancers. Notch signaling activation mostly relies on the activity of the γ-secretase enzyme that cleaves the Notch receptors and releases the active intracellular domain. It is well-documented that γ-secretase inhibitors (GSIs) block the Notch activity, mainly by inhibiting the oncogenic activity of this pathway. To date, several GSIs have been introduced clinically for the treatment of various diseases, such as Alzheimer’s disease and various cancers, and their impacts on Notch inhibition have been found to be promising. Therefore, GSIs are of great interest for cancer therapy. The objective of this review is to provide a systematic review of in vitro and in vivo studies for investigating the effect of GSIs on various cancer stem cells (CSCs), mainly by modulation of the Notch signaling pathway. Various scholarly electronic databases were searched and relevant studies published in the English language were collected up to February 2020. Herein, we conclude that GSIs can be potential candidates for CSC-targeting therapy. The outcome of our study also indicates that GSIs in combination with anticancer drugs have a greater inhibitory effect on CSCs.     

Optimization of β-1,4-Endoxylanase Production by an Aspergillus niger Strain Growing on Wheat Straw and Application in Xylooligosaccharides Production

Plant biomass constitutes the main source of renewable carbon on the planet. Its valorization has traditionally been focused on the use of cellulose, although hemicellulose is the second most abundant group of polysaccharides on Earth. The main enzymes involved in plant biomass degradation are glycosyl hydrolases, and filamentous fungi are good producers of these enzymes. In this study, a new strain of Aspergillus niger was used for hemicellulase production under solid-state fermentation using wheat straw as single-carbon source. Physicochemical parameters for the production of an endoxylanase were optimized by using a One-Factor-at-a-Time (OFAT) approach and response surface methodology (RSM). Maximum xylanase yield after RSM optimization was increased 3-fold, and 1.41- fold purification was achieved after ultrafiltration and ion-exchange chromatography, with about 6.2% yield. The highest activity of the purified xylanase was observed at 50 °C and pH 6. The enzyme displayed high thermal and pH stability, with more than 90% residual activity between pH 3.0–9.0 and between 30–40 °C, after 24 h of incubation, with half-lives of 30 min at 50 and 60 °C. The enzyme was mostly active against wheat arabinoxylan, and its kinetic parameters were analyzed (K_m = 26.06 mg·mL⁻¹ and V_max = 5.647 U·mg⁻¹). Wheat straw xylan hydrolysis with the purified β-1,4 endoxylanase showed that it was able to release xylooligosaccharides, making it suitable for different applications in food technology.     

Comparison of catalytic performance of synthesized EU-1 zeolite with dealuminated EU-1 zeolite for <Emphasis Type="Italic">m</Emphasis>-xylene isomerization reaction

EU-1 zeolite was synthesized with high purity by a hydrothermal method and under optimum conditions: synthesis time 72 h, temperature 200°C, and aging time 12 h. Then, the synthesized EU-1 zeolite was modified by dealumination with nitric acid and the changes of the properties such as surface area, pore volume, and Si/Al ratio were investigated. The catalytic performance of these two catalysts was studied and compared with a commercial mordenite catalyst for meta-xylene isomerization reaction in a fixed bed reactor. The results showed that the modification of catalyst with acid increases Si/Al ratio from 25 to 50 due to the removal of a number of aluminium atoms from the framework of zeolite. Also the catalyst surface area increased from 300.237 m² g^?1 for EU-1 to 333.639 m² g^?1 for modified EU-1. According to results, the modified Eu-1 had higher para/ortho ratio, meta-xylene conversion, and para-xylene yield than EU-1 and commercial mordenite in the meta-xylene isomerization reaction.     

Preparation,characterization and use of sulfonylbis(1,4-phenylene)<Emphasis Type="Italic">bis</Emphasis>(sulfamic acid) as an eco-benign,efficient, reusable and heterogeneous catalyst for the synthesis of mono- and <Emphasis Type="Italic">bis</Emphasis>-chromenes

Sulfonylbis(1,4-phenylene)bis(sulfamic acid) (SPSA) is easily prepared and recognized as a new heterogeneous catalyst by the reaction of 4,4′-sulfonyldianiline with chlorosulfonic acid. This reagent was used for the synthesis of the mono- and bis-chromene derivatives. All reactions were performed under mild reaction conditions in high to excellent yields. The advantages of using the SPSA as a heterogeneous catalyst in these reactions are: being environmentally friendly, low cost, commercially availability and easy to separate from the mixture of the reaction and high reusable catalyst. Using this catalyst, results in acceptable reaction time and high yields with high purity of the obtained products without utilizing any organic solvents. The catalyst was characterized by FT-IR, ¹H NMR, ¹³C NMR, mass and TGA studies. All the products were characterized by FT-IR, ¹H, ¹³C NMR, HRMS, melting point and elemental analyses.     

[Bmim]<Subscript>5</Subscript>[PNiW<Subscript>11</Subscript>O<Subscript>39</Subscript>]·3H<Subscript>2</Subscript>O an organic–inorganic hybrid as catalyst for one-pot pseudo-five-component synthesis of tetrazolyldiazepines

In this research, two heterogeneous organic–inorganic hybrid catalysts, [bmim]₃[PW₁₂O₄₀]·3H₂O and [bmim]₅[PNiW₁₁O₃₉]·3H₂O, have been prepared. The catalysts were fully characterized by several techniques such as elemental analyses, Fourier transform infrared spectroscopy, thermo-gravimetric analysis, scanning electron microscope and energy-dispersive X-ray analysis. Next, the hybrid catalysts have been used for the synthesis of functionalized diazepines containing tetrazole ring. Tetrazolyl-1H-spiro[benzo[b]cyclopenta[e][1,4] diazepines products were obtained in excellent yields and mild experimental conditions using [bmim]₅[PNiW₁₁O₃₉]·3H₂O as catalyst. This process was carried out via a one-pot, pseudo-five-component condensation reaction by means of a 1,2-diamine, isocyanide, TMSN3 and two molecules of a linear or cyclic ketone in methanol, at ambient temperature.