VOLUME 42, NO4, AUG-2020

Synthesis and Evaluation of Hydroxymethyl Tetramides as Flow Improvers for Crude Oil

In this work, a series of hydroxymethyl tetramide (HMTEA) was synthesized from vegetable oil, triacetylenetetramine and hexamethylenetetramine, which was evaluated as viscosity reducer and pour point depressor for crude oil. The results showed that HMTE has a good viscosity reduction effect on the crude oil from Yanchang Oilfield, with the highest viscosity reduction rate of 93%. The highest pour point reduction depression was achieved as 6.5℃. Differential scanning calorimetry and paraffin crystal morphology characterization were conducted on the crude oil to elucidate the mechanism of viscosity reduction and pour point depression.read more

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Xuefan Gu, Peng Wang, Zhen Guo, Weichao Du, Sanbao Dong

Effect of pH and Dodecylamine Concentration on the Properties of Dodecylamine Two-Phase foam

Over-stabilized foam has always been a problem that plagues the dodecylamine (DDA) flotation system. In this study, a new device, “automatic foam analyzer”, was successfully used to characterize the behavior of foam in DDA solution. The effects of pH and DDA dosage on the foam properties were investigated from four aspects: bubble diffusion capacity, Bikerman coefficient, half-life period and solution conductivity, and the mechanism of pH and DDA concentration on foam properties was analyzed by solution chemistry and surface tension of DDA, then the change process of foam structure was deduced. The results showed that the foaming property and stability of DDA bubbles were the best at pH=8. Simultaneously, with the increase of DDA dosage, the foaming property of bubbles was enhanced, the half-life was prolonged, and the foam stability was also improved.read more

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Weimin Xie, Dongsheng He, Shuang Liu, Fei Chen, Hongqiang Li

Synthesis and Characterization of CuMnOx-Bentonite as Efficient Catalyst for Oxidation of m-xylene

Catalytic oxidation of organic volatile compounds (VOCs) is considered superior to conventional methods because very low concentration of VOCs can also be oxidized and removed at low temperatures without consumption of addditional fuel and introduction of NOx compounds into the environment. Herein, the synthesis of MnO2 nanoparticles on bentonite (Bent) support in the presence of CuO for catalytic oxidation of m-xylene is reported. The synthesized materials were analyzed with FT-IR, XRD, and TEM analysis for structural and morphological characterization. XRD and TEM analysis indicated the formation of δ-MnO2 with sheet structure on Bent surface. Temperature-programmed reduction (H2-TPR) of hydrogen was used to investigate catalytic performance of δ-MnO2 towards oxidation of m-xylene at different temperatures. The catalytic activity was strongly dependent on the δ-MnO2 content in the synthesized material. 100 % oxidation of m-xylene with observed with 10% Mn content at temperature below than 325 oC. Intersetingly introduction of CuO greatly improved the catalytic activity of Mn-Bent materials. The presence of Cu in Mn-Bent has greatly reduced the temperature for complete oxidation of m-xylene. In this case100% conversion of m-xylene was observed at 250 oC.read more

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Mo Thi Nguyen, Cam Minh Le, Tuan Minh Nguyen, Hao Hoang Nguyen, Anwar-ul-Haq Ali Shah Hung Van Hoang

Neuroprotectıve Potential of the Tubers of Corydalis triternata Zucc. Growing in Turkey

The continuing research for the determination of bioactive secondary metabolites from Turkish geophytes as therapeutic agents for dementia is mainly based on the need for drug candidates affected to brain areas. In this study, the in vitro anticholinesterase activity of the alkaloidal fractions of the tubers of Corydalis triternata Zucc. was investigated for their neuroprotective potential. Furthermore, the content of the active alkaloid fractions of the tubers was determined by LC-Q-TOF-MS. The tubers of Corydalis triternata Zucc. were collected from Hatay province of Turkey. The plant species were also preserved as ex-situ in Yalova-Turkey. The alkaloidal extract was prepared from the tubers. The anticholinesterase activities of the extracts and fractions were tested by modification of the Ellman’s method. The optimization of LC-MS conditions was used in ESI in the positive ion mode. The in vitro tests were highlighted that the alkaloidal extract of the tubers exhibited the highest activity against AChE and BuChE with IC50 values of 17.56 ± 1.0 g/mL and 326.23 ± 2.6 g /mL (galanthamine 6.8 ± 0.5 g /mL and 344.4 ± 8.2 g /mL as positive control), respectively. The fractions CK-3 and 4 were showed the highest inhibitory activity against AChE with the IC50 value (6.88 ± 0.3 g mL and 7.26 ± 0.3 g /mL), the fractions CK-5,6,7 and 8 have indicated potent inhibitory activities by compared with galanthamine, which was used as positive control with IC50 value 6.8 ± 0.5 g /mL. Among the fractions obtained from the alkaloidal extract, protoberberine-type alkaloids were exerted the most promising activity against both cholinesterases. The present study was described for the first time the in vitro anticholinesterase activity of Corydalis triternata Zucc. as neuroprotective potential and their metabolite profile by LC-Q-TOF-MS. Besides, the anticholinesterase assays on alkaloidal extract and its fractions showed that protoberberine-type alkaloids were determined the most potent inhibitor against AChE and BuChE.read more

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Mehtap Kılıc, Erdal Kaya, Ayhan Ibrahim Aysal, Bilge Sener

Development of Rapid Colorimetric Assay for Detection of Gluconic Acid Using Iron(Ⅱ) and Indigo Carmine

In this work, a simple and rapid spectrophotometric method, which is based on the fact that Iron(Ⅱ) -gluconic acid complex as a kind of reducing agent deterioration of indigo carmine dyes, was developed to detect gluconic acid in food. Under the optimal experimental condition, a linear range of 3.6 M to 900 M was obtained for gluconic acid with a limit of detection of 1.1 μM. The colorimetric method was rapid and robust with a low cost and can be applied to gluconic acid detection in food samples.read more

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Yifeng Lan, Lixiang Zuo, Yangyang Zhou, Yanli Wei and Chuan Dong

Catalytic Activity and Kinetic Studies of Core@Shell Nanostructure NiFe2O4@TiO2 for Photocatalytic Degradation of Methyl Orange Dye

Current research focuses on synthesis and characterization of magnetically separable core@shell (NiFe2O4@TiO2) nanostructured photocatalyst with different weight percent (10, 20, 30, and 40) TiO2 using simple wet chemical techniques. Magnetic core with TiO2 shell was synthesized by the hydrolysis of TTIP precursor with NiFe2O4 nanoparticles. NiFe2O4 nanoparticles were synthesized by the sol-gel auto combustion method. The synthesized nanostructures were characterized for structural, morphological and magnetic behavior using XRD, TEM, SEM and VSM while the surface area was calculated using Brunauer-Emmett-Teller analyzer. Pure nickel ferrite was indexed as spinel FCC crystal structure while anatase titania was confirmed from the characteristic peaks in the indexed XRD patterns. SEM images show the uniform particle size and spherical morphology with average size of 18.85 nm±2nm. The Surface area of prepared core@shell nanostructures was found as 258 m2/g for 10 wt. % TiO2 photocatalyst. A decrease in surface area has been observed with the increase in TiO2 percentage. The photo-catalytic degradation of MO was studied using UV-Visible spectroscopy under NiFe2O4-TiO2 catalyst. UV-spectra revealed degradation of methyl orange by the decrease in the characteristic peak at 460 nm. Kinetics of degradation reaction were studied by the integral method of analysis using UV absorbance data at 460 nm. The photo-catalytic activity of as synthesized catalyst was enhanced many folds as compared to the pure nickel ferrite. M-H curves obtained from VSM revealed a decrease in the magnetization of nickel ferrite with a coating of non-magnetic TiO2.read more

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Mutawara Mahmood Baig, Erum Pervaiz, Muhammad Junaid Afzal

N-Octanol-Induced Phase Separation of Triton X-100 for the Extraction of Trace Silver from Environmental Samples with Flame Atomic Absorption Spectrometric Determination

A novel and simple cloud point extraction (CPE) method for detecting trace silver has been built up with flame atomic absorption spectrometry (FAAS) through adding proper amount of n-octanol into Triton X-100 resulting in an obvious decrease of the cloud point. In the method, rhodanine was chosen as chelating agent for the preconcentration of silver. The influence of major experimental parameters such as pH, chelating agent concentration, surfactant concentration, equilibration temperature and time on the extraction of silver from aqueous solutions was investigated and optimized. Under the optimal conditions, the minimum detection was 0.18 μg/L (3σ), while the preconcentration factor could reach up to 42. The well-pleasing results of standard reference sediment analysis manifested perfect accuracy and sensitivity of the method. Also, the presented method was applied to determine the trace silver in sediment and environmental water samples with satisfactory results.read more

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Juncui Xu, Fazhi Xie, Xianming Yue, Zhengyu Li, Shixiong Geng, Zhili Dai, Shiquan Xiong

Adsorption of Methylene Blue by Hydroxyl-Aluminum Pillared Montmorillonite

A purified raw montmorillonite and hydroxy-aluminum pillared montmorillonite have been prepared from a natural bentonite from Maghnia, Algeria. These materials have been analyzed by X-ray fluorescence spectroscopy, X-ray diffraction, Infrared spectroscopy and nitrogen adsorption-desorption measurement. The pillared montmorillonite provided a certain increase of interlayer basal spacing and BET surface area and consequently the improvement of its capacities adsorption and decolorization of Methylene Blue. The adsorption properties of these materials were studied as a function of contact time, solution pH, initial Methylene Blue concentration and temperature. The adsorption kinetics and isotherms were well fitted by pseudo-second order and Freundlich models, respectively. In addition to that, thermodynamic studies showed an exothermic and a spontaneous process.read more

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Houria Rezala, Houda Douba, Horiya Boukhatem and Amaya Romero

Synthesis and Biological Evaluation of Novel 4-Phenylaminobenzofuro[2,3-d]pyrimidine Derivatives

A series of novel 4-phenylaminobenzofuro[2,3-d]pyrimidine derivatives had been prepared and assessed for their in vitro antiproliferative activities against three lung cancer cell lines (A549, H460 and H1975). The bioassay results showed most of the designed compounds exhibited potential antiproliferation activities. Among them, compound 8f exhibited remarkable inhibitory activity against A549 and H460 cell lines with IC50 value of 2.54 μM and 2.68 μM, respectively, which was comparable to that of the positive control sorafenib (IC50 = 2.69 μM for A549 and 3.71 μM for H460). AO/EB staining suggests that compound 8f could induce apoptosis in A549 cells. Furthermore, cell cycle analyses show that compound 8f increased G0/G1 A549 cells arrest in a concentration-dependent manner. The preliminary structure-activity relationships (SARs) studies indicated that mono-electron-withdrawing groups (mono-EWGs) on the phenyl ring are positive on the antitumor activity.read more

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Ju liu, Jun Li, Jian-tao Shi, Jie Li, Xue-chen Hao, Duang-zheng Song, Yang Wang, Shi Ding and Ye Chen

Synthesis of Nitro- and Aminoisoflavones and their Effects on the Proliferation of Endothelial Cells

The new nitroisofalvones 2a-k were synthesized via nitration of the corresponding isoflavones 1a-f using NH4NO3/TFAA in acetonitrile. The aminoisoflavones 3a-g, also new, were produced by selective reduction of the corresponding nitroisoflavones with SnCl2.2H2O. The nitro- and aminoisoflavones, tested in vitro concerning their effects on the proliferation of endothelial cells showed modest activities. All the new products are fully characterized and the nitro compounds analyzed thoroughly by NMR to allow complete assignment of the proton and carbon resonance and to establish the orientation of nitration.read more

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Nawaf Al-Maharik, Nidal Jaradat, Adel Hidmi