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51.
Characteristics and Composition of Watermelon Seed Oil and Solvent Extraction Parameters Effects 总被引:1,自引:0,他引:1
Zahra Moaddabdoost Baboli Ali Akbar Safe Kordi 《Journal of the American Oil Chemists' Society》2010,87(6):667-671
Watermelon seed oil characteristics were evaluated to determine whether this oil could be exploited as an edible oil. Hexane
extraction of watermelon seeds produced yields of 50% (w/w) oil. The refractive index, saponification and iodine value were
1.4712 (at 25 °C), 200 mg KOH/g and 156 g I/100 g, respectively. The acid and peroxide values were 2.4 mg KOH/g and 3.24 mequiv/kg,
respectively. The induction time of the oil was also 5.14 h at 110 °C, which was measured for the first time. Total unsaturation
contents of the oil was 81.6%, with linoleic acid (18:2) being the dominant fatty acid (68.3%). Considering that the watermelon
seed oil was highly unsaturated, the relatively high induction time might indicate the presence of natural antioxidants. In
addition, the influence of extraction parameters on extraction of oil from watermelon seed with hexane as a solvent was studied
at several temperatures (40, 50, and 60 °C), times (1, 2, and 3 h) and solvent/kernel ratios (1:1, 2:1, and 3:1). The oil
yield was primarily affected by the solvent/kernel ratio and then time and temperature, respectively. The protein content
of the oil-free residue was 47%. 相似文献
52.
Abdolmajid Bayandori Moghaddam Mohammad Reza Ganjali Ali Akbar Saboury Ali Akbar Moosavi-Movahedi Parviz Norouzi 《Journal of Applied Electrochemistry》2008,38(9):1233-1239
This work describes the performance of a tyrosinase/nickel oxide nanoparticles/glassy carbon (Tyr/NiO NPs/GC) electrode. This
electrode was prepared by first applying a NiO NPs electrochemical deposition onto the GC electrode surface and then tyrosinase
immobilization was applied to the surface of electrodeposited NiO NPs. Scanning electron microscopy (SEM) and atomic force
microscopy (AFM) procedures demonstrated the existence of different NiO NP geometrical structures. These geometrical structures
could lead to better immobilization of proteins on their surfaces. The copper containing enzyme tyrosinase successfully achieved
electrical contact with the electrode because of the unique structural alignment of tyrosinase enzyme on the nanometer-scale
nickel oxide surfaces. This method could be suitable for application to nanofabricated devices facilitating better performance.
It was concluded that tyrosinase can be effectively applied to nanometer-scale nickel oxide surfaces. 相似文献
53.
Abdul Rehman Akbar Huihui Hu Muhammad Bilal Qadir Muhammad Tahir Zubair Khaliq Zhikang Liu Chuanxi Xiong Quanling Yang 《Ceramics International》2021,47(4):4648-4658
Technical development in electronic devices is frequently stifled by their insufficient capacity and cyclic stability of energy-storage devices. The nano-structured materials have sensational importance for providing novel and optimized combination to overcome exiting boundaries and provide efficient energy storage systems. Metal hydroxide materials with high capacity for pseudo-capacitance properties have grabbed special attention. Lately, the blend of nickel and cobalt hydroxides has been considered as a favorable class of metallic hydroxide materials owing to their comparatively high capacitance and exceptional redox reversibility. The sulfonated carbon nanotube fluid (SCNTF) was prepared by the ion exchange method to be utilized as the exceptional templates due to astonishing specific surface area, ensuring the maximum utilization of the active material. The CoNi-layered double hydroxides (LDHs)/SCNTF core-shell nanocomposite was prepared by the simple solvothermal method. Structural analysis showed that the composite material had the high conductance of carbon materials, the pseudo-capacitance characteristics of metal hydroxides, and porous structure, which facilitates the ion shuttle when the electrolyte reacts with the active material. Electrochemical analysis results showed that CoNi-LDHs/SCNTF had excellent rate performance, reversible charge-discharge properties and cycle stability. It exhibited an extreme specific capacity of 1190.5 F g?1 at a current density of 1 A g?1; whereas specific capacity remained 953.7 F g?1 at the current density was 10 A g?1. In addition, the capacity retention rate after 5000 charge-discharge cycles at a current density of 20 A g?1 was 81.0%. The results indicated that the CoNi-LDHs/SCNTF core-shell nanocomposite material is cost efficient and an effective substitute in energy storage applications. 相似文献
54.
Ahmad Feyz Dizaji Hossein Ali Sepiani Farzad Ebrahimi Akbar Allahverdizadeh Hasan Ali Sepiani 《Journal of Mechanical Science and Technology》2009,23(8):2299-2307
An initial-boundary value problem that is Duffing’s oscillator with time varying coefficients will be studied. Using Banach’s
fixed-point theorem, the existence of periodic solution of the equation will be predicted. The method applied in this paper
is the Schauder second fixed point theorem, which includes the response of structures under vibratory force systems. As an
example, the dynamics of nonlinear simply supported rectangular thin plate under influence of a relatively moving mass is
studied. By expansion of the solution as a series of mode functions, the governing equations of motion are reduced to an ordinary
differential equation for time development vibration amplitude, which is Duffing’s oscillator. Finally, a parametric study
is developed, after that some numerical examples are solved, and the validity of the present analysis is clearly shown.
This paper was recommended for publication in revised form by Associate Editor Maenghyo Cho
Hossein Ali Sepiani received his B.S. degree in Mechanical Engineering from University of Kashan, Iran, in 2003. He then received his M.S. degree
from University of Tehran, in 2006. Currently, Hossein is continuing his research at University of Tehran. His research interests
include new materials (FGMs, Nano-materials, SMAs, SMPs, etc), Composites (Woven Fabrics and Fiber Metal Laminates), Smart
Materials (Shape Memory Alloy, Magnet/Electro-rheological and Piezoelectric Sensors and Actuators), Intelligent structures
(Structures integrated with smart materials), Vibration and control of Intelligent Structures and their application.
Ahmad Feyz Dizaji got his B.S. degree from University of Tehran, Iran, in 1970. Then he continued his study in U.S. and received his PhD. degree
from Michigan State University in 1983, in Applied Mathematics under the supervision of Professor Shui-ni Chow and Professor
J. Mallet-Paret. Since then he has been a member of the Faculty of Engineering in University of Tehran, teaching mathematics
in both undergraduate and graduate levels. 相似文献
55.
Akbar Ghaffar Pour Rahbar 《Photonic Network Communications》2009,17(3):226-237
Optical Packet Switching (OPS) can provide the ever-increasing bandwidth required for Internet traffic and new applications
for future networks. However, optical packet loss is the major problem for an OPS network. Moreover, by increasing the number
of hops between a pair of ingress–egress switches in an OPS network, optical Packet Loss Rate (PLR) between this pair is increased.
Therefore, due to a higher PLR for long-hop TCP connections, the throughput of these connections may be much lower than the
short-hop TCP connections. To overcome this problem, it is proposed in this paper to use the retransmission idea in the optical
domain not only to increase TCP throughput but also to improve the throughput of multi-hop TCP connections, and also to have
a loss-free OPS network. Under retransmission in the optical domain, a copy of the transmitted traffic is kept in the electronic
buffers of ingress switches and retransmitted in the optical domain whenever required. Note that the TCP layer has its own
retransmission at the client packet level as well. By retransmission of lost packets in the optical domain, TCP would be unaware
of the lost client packets, and therefore, TCP would not reduce its sending rate. In this paper, TCP throughput is studied
in a bufferless slotted OPS network and the effectiveness of the proposed mechanism is evaluated.
相似文献
Akbar Ghaffar Pour RahbarEmail: Email: |
56.
Stimulated Raman scattering (SRS) with ordinary (O-mode) wave at phase space (x, v) is investigated. For this purpose Vlasov equation is solved with one simulation method. Evolution of distribution function for an early time and a later time is presented. Initial distribution function has Gaussian shape, that is important in plasma heating, but as the time passed, this function due to the perturbation extends over space and velocity. In this situation, the behavior of distribution function has an important role in instability rate. Then instability rate for SRS is obtained and these results are showed in some special times and special cells. Density fluctuations affect instability rate and there is no remarkable damping at early times. At later times instability rate reduces sensitively which is in accordance to electron plasma wave damping and then heating the electrons. Also with increase in frequency of the incident wave, the instability rate due to saturation decreases sensitively. 相似文献
57.
Isa MH Ibrahim N Aziz HA Adlan MN Sabiani NH Zinatizadeh AA Kutty SR 《Journal of hazardous materials》2008,152(2):662-668
This study proposed an oil palm by-product as a low-cost adsorbent for the removal of hexavalent chromium [Cr (VI)] from aqueous solution. Adsorption of Cr (VI) by sulphuric acid and heat-treated oil palm fibre was conducted using batch tests. The influence of pH, contact time, initial chromium concentration and adsorbent dosage on the removal of Cr (VI) from the solutions was investigated. The optimum initial pH for maximum uptake of Cr (VI) from aqueous solution was found to be 1.5. The removal efficiency was found to correlate with the initial Cr (VI) concentration, adsorbent dosage as well as the contact time between Cr (VI) and the adsorbent. The adsorption kinetics tested with pseudo first order and pseudo second order models yielded high R(2) values from 0.9254 to 0.9870 and from 0.9936 to 0.9998, respectively. The analysis of variance (ANOVA) showed significant difference between the R(2) values of the two models at 99% confidence level. The Freundlich isotherm (R(2)=0.8778) described Cr (VI) adsorption slightly better than the Langmuir isotherm (R(2)=0.8715). Difficulty in desorption of Cr (VI) suggests the suitability of treated oil palm fibre as a single-use adsorbent for Cr (VI) removal from aqueous solution. 相似文献
58.
Pooneh Bagheri Zadeh Akbar Sheikh Akbari Tom Buggy John Soraghan 《Multimedia Tools and Applications》2010,49(2):347-370
In this paper a novel multiresolution human visual system and statistically based image coding scheme is presented. It decorrelates
the input image into a number of subbands using a lifting based wavelet transform. The codec employs a novel statistical encoding
algorithm to code the coefficients in the detail subbands. Perceptual weights are applied to regulate the threshold value
of each detail subband that is required in the statistical encoding process. The baseband coefficients are losslessly coded.
An extension of the codec to the progressive transmission of images is also developed. To evaluate the performance of the
coding scheme, it was applied to a number of test images and its performance with and without perceptual weights is evaluated.
The results indicate significant improvement in both subjective and objective quality of the reconstructed images when perceptual
weights are employed. The performance of the proposed technique was also compared to JPEG and JPEG2000. The results show that
the proposed coding scheme outperforms both coding standards at low compression ratios, while offering satisfactory performance
at higher compression ratios. 相似文献
59.
Daya Ali Akbar 《矿业科学技术学报(英文版)》2012,22(4):573-577
This paper is devoted to application of ordinary kriging method in Choghart north anomaly iron ore deposit in Yazd province, Iran. In order to estimate the deposit, 2329 input data gained from 26 boreholes were used. Fe grade was selected as the major regional variable on which the present research has focused. All of the available data were changed to 12.5 m composites so that statistical regularization could be reached. Studies indicated that iron grade input data had single-population characteristics. To carry out ordinary kriging, a spherical model was fitted over empirical variogram. Then the model was verified through cross validation method and proved to be valid with a coherence coefficient of 0.773 between the estimated and real data. Plotting the empirical variogram in different directions showed no geometric anisotropy for the deposit. To estimate the Iron grade, ordinary kriging method was used according to which, all of the exploitable blocks with dimensions 20 m × 20 m × 12.5 m were block estimated within the estimation space. Finally tonnage-grade curve has been drawn and reserve classified into measured, indicated and inferred. 相似文献
60.
Akbar Mobinikhaledi Hassan Moghanian Parvin Safari Elnaz Firuzian 《Journal of Inorganic and Organometallic Polymers and Materials》2018,28(3):631-642
Two superparamagnetic and heat resistant xanthene based poly(ether-imide) nanocomposites were successfully synthesized. Field emission scanning electron microscopy, transmission electron microscope, X-ray diffraction, thermal gravimetric analysis, vibrating sample magnetometer, Energy-dispersive X-ray spectroscopy and Fourier-transform infrared (FTIR) techniques were used for studying the morphology, crystalline phase, thermal stability and magnetization properties of the nanocomposites. The neat form of the corresponding poly(ether-imide) was also prepared by thermal imidization method and its structure was confirmed by FTIR, proton nuclear magnetic resonance (1H NMR), UV–Vis and photoluminescence (PL) spectroscopies. In order to investigate the effects of modifying the surface of Fe3O4 nanoparticles on thermal properties of the nanocomposites, the surface of Fe3O4 nanoparticles was coated with SiO2 and polysuccinimide (PSI), sequentially. Then, both the unmodified Fe3O4 and surface-modified Fe3O4 (Fe3O4@SiO2–PSI) nanoparticles were used as fillers for the polymer matrix. According to the results, the prepared nanocomposites were superparamagnetic and showed higher thermal stability in comparison to the neat poly(ether-imide). Furthermore, poly(ether-imide)/Fe3O4@SiO2–PSI (PIEN 10b) nanocomposite showed higher thermal stability and dispersed better in the polymer matrix [in comparison to poly(ether-imide)/Fe3O4 (PIEN 10 a)] due to the presence of imide groups and high hydroxyl content of the functional Fe3O4 nanoparticles which caused high interactions between poly(ether-imide) and functional Fe3O4. Furthermore, the presence of methyl, ether and bulky xanthene groups in the poly(ether-imide(backbone improved the solubility of the neat polymer in organic solvents. These properties can be very helpful for extending new applications of poly(ether-imide)s. 相似文献