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81.
A split plot 3 × 3 experiment was designed to examine the impact of three concentrations of CO? (400, 800 and 1,200 μmol·mol?1) on the phenolic and flavonoid compound profiles, phenylalanine ammonia lyase (PAL) and antioxidant activity in three varieties of Labisia pumila Benth. (var. alata, pumila and lanceolata) after 15 weeks of exposure. HPLC analysis revealed a strong influence of increased CO? concentration on the modification of phenolic and flavonoid profiles, whose intensity depended on the interaction between CO? levels and L. pumila varieties. Gallic acid and quercetin were the most abundant phenolics and flavonoids commonly present in all the varieties. With elevated CO? (1,200 μmol·mol?1) exposure, gallic acid increased tremendously, especially in var. alata and pumila (101-111%), whilst a large quercetin increase was noted in var. lanceolata (260%), followed closely by alata (201%). Kaempferol, although detected under ambient CO? conditions, was undetected in all varieties after exposure. Instead, caffeic acid was enhanced tremendously in var. alata (338~1,100%) and pumila (298~433%). Meanwhile, pyragallol and rutin were only seen in var. alata (810 μg·g?1 DW) and pumila (25 μg·g?1 DW), respectively, under ambient conditions; but the former compound went undetected in all varieties while rutin continued to increase by 262% after CO? enrichment. Interestingly, naringenin that was present in all varieties under ambient conditions went undetected under enrichment, except for var. pumila where it was enhanced by 1,100%. PAL activity, DPPH and FRAP also increased with increasing CO? levels implying the possible improvement of health-promoting quality of Malaysian L. pumila under high CO? enrichment conditions. 相似文献
82.
Numerical investigation of turbulent free jet flows issuing from rectangular nozzles: the influence of small aspect ratio 总被引:1,自引:0,他引:1
Ehsan Faghani Reza Maddahian Pedram Faghani Bijan Farhanieh 《Archive of Applied Mechanics (Ingenieur Archiv)》2010,80(7):727-745
In this research, the fluid and thermal characteristics of a rectangular turbulent jet flow is studied numerically. The results
of three-dimensional jet issued from a rectangular nozzle are presented. A numerical method employing control volume approach
with collocated grid arrangement was employed. Velocity and pressure fields are coupled with SIMPLEC algorithm. The turbulent
stresses are approximated using k–e{\varepsilon} model with two different inlet conditions. The velocity and temperature fields are presented and the rates of their decay
at the jet centerline are noted. The velocity vectors of the main flow and the secondary flow are illustrated. Also, effect
of aspect ratio on mixing in rectangular cross-section jets is considered. The aspect ratios that were considered for this
work were 1:1 to 1:4. The results showed that the jet entrains more with smaller AR. Special attention has been drawn to the
influence of the Reynolds number (based on hydraulic diameter) as well as the inflow conditions on the evolution of the rectangular
jet. An influence on the jet evolution is found for smaller Re, but the jet is close to a converged state for higher Reynolds numbers. The inflow conditions have considerable influence
on the jet characteristics. 相似文献
83.
Mahdi Alipour Mohammad Amin Torabi Mohammad Sareban Hadi Lashini Ehsan Sadeghi Abolfazl Fazaeli 《基于设计的结构力学与机械力学》2020,48(5):525-541
AbstractIn this article, we investigated the effect of martensite morphology on the mechanical properties and formability of dual phase steels. At first, three heat treatment cycles were subjected to a low-carbon steel to produce ferrite–martensite microstructure with martensite morphology of blocky-shaped, continuous, and fibrous. Tensile tests were then carried out so as to study mechanical properties, particularly the strength and strain hardening behavior of dual phase steels. In order to study the formability of dual phase samples, Forming Limit Diagram was obtained experimentally and numerically. Experimental forming limit diagram was obtained using Nakazima forming test, while Finite Element Method was utilized to numerically predict the forming limit diagram. The results indicated that the dual phase samples with fibrous martensite morphology had the highest tensile properties and strain rate hardening out of the three different microstructures. Blocky-shaped martensite morphology, on the other hand, had the worst mechanical properties. The study of the strain hardening behavior of dual phase sample by Kocks–Mecking-type plots, evinced two stages of strain hardening for all specimens with different microstructures: stages III and IV. The forming limit diagram of dual phase steels also proved that samples with fibrous martensite morphology had the best formability compared to other two microstructures. The simulated forming limit diagram manifested that there is a good agreement between experimental results and those obtained by FEM. 相似文献
84.
Iman Jafari Mohamadreza Shakiba Fatemeh Khosravi Seeram Ramakrishna Ehsan Abasi Ying Shen Teo Mohammadreza Kalaee Majid Abdouss Ahmad Ramazani S. A Omid Moradi Erfan Rezvani Ghomi 《Molecules (Basel, Switzerland)》2021,26(6)
The incorporation of nanofillers such as graphene into polymers has shown significant improvements in mechanical characteristics, thermal stability, and conductivity of resulting polymeric nanocomposites. To this aim, the influence of incorporation of graphene nanosheets into ultra-high molecular weight polyethylene (UHMWPE) on the thermal behavior and degradation kinetics of UHMWPE/graphene nanocomposites was investigated. Scanning electron microscopy (SEM) analysis revealed that graphene nanosheets were uniformly spread throughout the UHMWPE’s molecular chains. X-Ray Diffraction (XRD) data posited that the morphology of dispersed graphene sheets in UHMWPE was exfoliated. Non-isothermal differential scanning calorimetry (DSC) studies identified a more pronounced increase in melting temperatures and latent heat of fusions in nanocomposites compared to UHMWPE at lower concentrations of graphene. Thermogravimetric analysis (TGA) and derivative thermogravimetric (DTG) revealed that UHMWPE’s thermal stability has been improved via incorporating graphene nanosheets. Further, degradation kinetics of neat polymer and nanocomposites have been modeled using equations such as Friedman, Ozawa–Flynn–Wall (OFW), Kissinger, and Augis and Bennett’s. The "Model-Fitting Method” showed that the auto-catalytic nth-order mechanism provided a highly consistent and appropriate fit to describe the degradation mechanism of UHMWPE and its graphene nanocomposites. In addition, the calculated activation energy (Ea) of thermal degradation was enhanced by an increase in graphene concentration up to 2.1 wt.%, followed by a decrease in higher graphene content. 相似文献
85.
Nikooei Niusha Dekamin Mohammad G. Valiey Ehsan 《Research on Chemical Intermediates》2020,46(8):3891-3909
Research on Chemical Intermediates - Benzene-1,3,5-tricarboxylic acid-functionalized MCM-41 (MCM-41-Pr-BTA), as a novel hybrid organosilica, was prepared and properly characterized by the... 相似文献
86.
Hosseini Seyed Ehsan Butler Brayden 《Journal of Thermal Analysis and Calorimetry》2021,144(3):763-778
Journal of Thermal Analysis and Calorimetry - Solar is one of the most promising energy sources because of the abundance of solar radiation in certain parts of the world. One of the main limiting... 相似文献
87.
88.
Masoud Homayouni-Tabrizi Ehsan Karimi Farideh Namvar Mozhgan Soltani Vahid Pouresmaeil 《Research on Chemical Intermediates》2018,44(11):6537-6548
The aim of the present study is to evaluate the antioxidant and proapoptotic effects of silver–palm pollen (Ag/PP) nanocomposite. The percentage of live cells after treatment with various concentrations of Ag/PP (0, 5, 10, 20, and 40 µM/mL) was determined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) colorimetric assay. The antioxidant potential of Ag/PP was measured via the scavenging effects of 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) and molecular analysis. Apoptosis was assessed by morphological analysis, fluorescent dye, and flow cytometry, and its fundamental mechanism studied based on evaluation of Bax and Bcl2 gene expression. Ag/PP nanocomposite suppressed the viability of MCF-7 cells (dose and time dependently) and showed antioxidant properties. Morphological changes associated with cell death were observed in treated cells. Accumulation of dead cells in sub-G1 phase confirmed the occurrence of apoptosis in exposed cells. In addition, NPs induced cell death by altering Bcl-2 expression in MCF-7 cells. These results indicate that Ag/PP nanocomposite is an effective combination for removal of cancer cells by induction of apoptosis and could be useful for human health due to its antioxidant effects. 相似文献
89.
Ehsan Karimi Meisam Habibi Mahdi Ebrahimi Ali Mehrafarin Farahnaz Khalighi-Sigaroodi 《Natural product research》2018,32(16):1991-1995
The antioxidant activities of crude extract fractions using Hexane, Chloroform, Ethyl Acetate, Butanol and Water of Clematis orientalis and Clematis ispahanica were investigated. 1,1-diphenyl-2-picryl-hydrazyl (DPPH) assay and the ferric reducing/antioxidant potential (FRAP) were used to evaluate the antioxidant capacity. The total phenolics were found to be 4.37–9.38 and 1.32–11.37 mg gallic acid equivalents (GAE)/g in different fractions for C. orientalis and C. ispahanica, respectively. The ethyl acetate fraction of C. orientalis and chloroform fraction of C. ispahanica showed the highest DPPH and FRAP activities at a concentration of 300 μg/mL. The predominant phenolic compounds identified by HPLC in C. orientalis were Resorcinol (603.5 μg/g DW) in chloroform fraction and Ellagic acid (811.7 μg/g DW) in chloroform fraction of C. ispahanica. 相似文献
90.
Ayoub Taavoni-Gilan Ehsan Taheri-Nassaj Mojtaba Shamsipur 《Journal of the Iranian Chemical Society》2018,15(12):2759-2769
Nanostructured TiO2/ZrO2 composite membranes with varying compositions were obtained by sol–gel technique. The influence of 0–30 mol% zirconia doping on microstructure, water permeability, photocatalytic and physical separation properties, removal of methyl violet of textile industries wastewater and thermal and mechanical stability of titania/zirconia composite membranes was described. Firstly, alumina supports were coated with TiO2 intermediate layers using the colloidal sol–gel route. The TiO2/ZrO2 composite sols were prepared via a polymeric sol–gel method and dip-coated on TiO2 intermediate layer. The samples were characterized by DLS, TG-DTA, XRD, FTIR, BET-BJH, UV–visible, SEM, TEM and AFM. It was shown that zirconia retards the phase transformation of anatase to rutile until at least 700 °C. The minimum pore size and maximum surface area obtained were 1.2 nm and 153 m2/g, respectively, attributed to the sample with 20 mol% zirconia. The mechanical strength of titania membranes was significantly improved by addition of zirconia. The most methyl violet removal efficiency obtained, with and without UV-irradiation, is 80.8 and 72.6%, respectively, attributed to the sample with 20 mol% zirconia. 相似文献