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61.
In this article, the equation of motion for a rotating nanocantilever has been developed based on the Euler–Bernoulli beam model, which includes the effect of temperature, small scale effect, and centrifugal force. A power series method has been employed to obtain the exact solution of the natural frequencies. The results also compared with other solutions of exact and approximate differential quadrature method. The effects of temperature, angular velocity, and small scale in the vibration characteristics of a rotating nanocantilever beam are investigated. It is shown that the effect of temperature plays a significant role in the behavior of the vibration of a rotating nanocantilever. Nondimensional frequency increases in the first mode with increasing the nonlocal parameter while it is inverse for the second and third modes of vibration. 相似文献
62.
Seyed Mojtaba Tabatabaeipour 《International journal of systems science》2013,44(11):1917-1933
Active fault detection and isolation (AFDI) is used for detection and isolation of faults that are hidden in the normal operation because of a low excitation signal or due to the regulatory actions of the controller. In this paper, a new AFDI method based on set-membership approaches is proposed. In set-membership approaches, instead of a point-wise estimation of the states, a set-valued estimation of them is computed. If this set becomes empty the given model of the system is not consistent with the measurements. Therefore, the model is falsified. When more than one model of the system remains un-falsified, the AFDI method is used to generate an auxiliary signal that is injected into the system for detection and isolation of faults that remain otherwise hidden or non-isolated using passive FDI (PFDI) methods. Having the set-valued estimation of the states for each model, the proposed AFDI method finds an optimal input signal that guarantees FDI in a finite time horizon. The input signal is updated at each iteration in a decreasing receding horizon manner based on the set-valued estimation of the current states and un-falsified models at the current sample time. The problem is solved by a number of linear and quadratic programming problems, which result in a computationally efficient algorithm. The method is tested on a numerical example as well as on the pitch actuator of a benchmark wind turbine. 相似文献
63.
Hamid Reza Rajabi Mojtaba Shamsipur Seied Mahdi Pourmortazavi 《Materials science & engineering. C, Materials for biological applications》2013,33(6):3374-3381
This work reports the first application of the ion imprinting technology for determination of potassium ion by precipitation polymerization method. Ion imprinted polymeric (IIP) nanoparticles were prepared by using dicyclohexyl 18C6 (DC18C6) as a K+ ion selective crown ether, in the acetonitrile–dimethylsulfoxide (3:1; v/v) mixture as porogen. The imprint potassium ion was removed from the polymeric matrix using 0.5 M HNO3. The scanning electron microscopy (SEM) micrographs showed colloidal nanoparticles of 60–90 nm in diameter and slightly irregular in shape. The obtained ion-imprinted particles for K+ showed selective recognition with rapid adsorption and desorption processes. It was found that imprinting results in increased affinity of the material toward K+ ion over other competitor metal ions with the same charge and/or close ionic radius. The synthesized IIP nanobeads were shown to be promising for solid-phase extraction coupled with flame photometry for determination of trace K+ ion in different water samples. 相似文献
64.
Mehdi Kiani M. Sharif Bakhtiar Mojtaba Atarodi 《Analog Integrated Circuits and Signal Processing》2010,62(3):319-325
This paper presents a low voltage low noise open loop automatic amplitude control method for voltage-controlled oscillators
(VCO’s). In this method a feedback mechanism keeps the VCO at its optimum amplitude over temperature and process variations
and then the loop is broken to avoid noise injection form the control circuitry to the VCO. The loop does not add extra noise
to the VCO. Based on the proposed method, a low voltage low noise LC-VCO was designed for a low phase noise application in
TSMC 0.18 micron RFCMOS technology. Simulations show considerable improvement in the phase noise with the application of the
proposed method. 相似文献
65.
The composition of essential oils from aerial parts of Heracleum persicum, a widely used medicinal plant, and three other Heracleum species growing wild in Iran were analysed by GC and GC–MS. Myristicin (53.6%), (E)-anethole (25.0%), hexyl butanoate (29.7%) and elemicin (41.1%) were the major compounds of Heracleum pastinacifolium, H. persicum, Heracleum rechingeri and Heracleum transcaucasicum, respectively. Cytotoxic activity assessed on three human cancer cell lines (HeLa, LS180 and Raji), showed that essential oils from H. transcaucasicum (IC50 values; 0.362–0.594 mg/ml) followed by H. pastinacifolium (0.497–1.398 mg/ml) had moderate antitumoral activities. In the DPPH radical scavenging assay, H. pastinacifolium and H. persicum oils showed the highest activities with IC50 values of 7.3 and 7.4 mg/ml, respectively. Antioxidant activity correlated well with the total phenolic content of the oils. None of the essential oils showed significant antimicrobial activities. 相似文献
66.
Amphiphilic block copolymers are macromolecular compounds of great importance from both fundamental scientific and many technological
point of views for a large variety of applications. Amphiphilic diblock copolymer containing segments of monomethoxypoly(ethylene
glycol) and polystyrene (MPEG-b-PS) was synthesised by a convenient method for preparation of macroinitiator MPEG-TEMPO for
‘living’ free radical polymerization (NMRP technique). Initially, derivative of MPEG with chlorine function has been prepared
in an one-step reaction with thionyl chloride. 1-hydroxy-2,2,6,6-tetramethyl-piperidine (TEMPO-OH) obtained by reduction of
2,2,6,6-tetramethyl-piperidinyl-1-oxy (TEMPO) with sodium ascorbate was coupled with chlorinated MPEG to yield the macroinitiator
MPEG terminated with a TEMPO unit (MPEG-TEMPO), which was further used to prepare the diblock copolymer MPEG-b-PS of styrene.
The product was purified and identified by 1H NMR, GPC and, FT-IR. 相似文献
67.
Mohammad Ali Faramarzi Nadia Zolfaghary Mojtaba Tabatabaei Yazdi Sina Adrangi Hossein Rastegar Mohsen Amini Mohsen Badiee 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2009,84(7):1021-1025
BACKGROUND: A large number of bacterial, fungal and microalgal species are able to bio‐transform steroid compounds. Among them, fungi from the Mucor genus have been shown to mediate hydroxylation, oxidation, and desaturation by the double bond formation and epoxidation of various steroid substances. Mucor racemocus has not been studied for its ability to modify androst‐1,4‐dien‐3,17‐dione, a pharmaceutically important steroid precursor. RESULTS: The filamentous fungus M. racemosus was applied for bioconversion of androst‐1,4‐dien‐3,17‐dione (ADD, I ) in a 5‐day fermentation. Microbial metabolites were purified chromatographically and identified on the basis of their spectral data as 17β‐hydroxyandrost‐1,4‐dien‐3‐one ( II ), 14α‐hydroxyandrost‐1,4‐dien‐3,17‐dione ( III ), 15α‐hydroxyandrost‐1,4‐dien‐3,17‐dione ( IV ), 15α,17β‐dihydroxyandrost‐1,4‐dien‐3‐one ( V ), 14α,17β‐dihydroxyandrost‐1,4‐dien‐3‐one ( VI ), and 6β,17β‐dihydroxyandrost‐1,4‐dien‐3‐one ( VII ). CONCLUSION: Observed modifications included hydroxylation at C‐6β, C‐14α, C‐15α positions and 17‐carbonyl reduction. The best fermentation conditions for production of hydroxysteroid‐1,4‐dien‐3‐one derivatives were found to be 25 °C at 150 rpm for 5 days with a substrate concentration of 0.5 g L?1. Copyright © 2009 Society of Chemical Industry 相似文献
68.
Mohammad Mojtaba Sadeghi Mohamed F. Salama Yusuf A. Hannun 《International journal of molecular sciences》2021,22(11)
Driver-directed therapeutics have revolutionized cancer treatment, presenting similar or better efficacy compared to traditional chemotherapy and substantially improving quality of life. Despite significant advances, targeted therapy is greatly limited by resistance acquisition, which emerges in nearly all patients receiving treatment. As a result, identifying the molecular modulators of resistance is of great interest. Recent work has implicated protein kinase C (PKC) isozymes as mediators of drug resistance in non-small cell lung cancer (NSCLC). Importantly, previous findings on PKC have implicated this family of enzymes in both tumor-promotive and tumor-suppressive biology in various tissues. Here, we review the biological role of PKC isozymes in NSCLC through extensive analysis of cell-line-based studies to better understand the rationale for PKC inhibition. PKC isoforms α, ε, η, ι, ζ upregulation has been reported in lung cancer, and overexpression correlates with worse prognosis in NSCLC patients. Most importantly, PKC isozymes have been established as mediators of resistance to tyrosine kinase inhibitors in NSCLC. Unfortunately, however, PKC-directed therapeutics have yielded unsatisfactory results, likely due to a lack of specific evaluation for PKC. To achieve satisfactory results in clinical trials, predictive biomarkers of PKC activity must be established and screened for prior to patient enrollment. Furthermore, tandem inhibition of PKC and molecular drivers may be a potential therapeutic strategy to prevent the emergence of resistance in NSCLC. 相似文献
69.
An experimental study has been carried out on the solids motion in a conical frustum-shaped vertical high shear mixer granulator by using the positron emission particle tracking (PEPT) technique. The mixer granulator has a vertical shaft attached to which are 4 sets of impellers at different elevations. The shaft is operated at 3, 6 and 12 Hz, which correspond to the top impeller tip speed of 2.1, 4.1 and 8.3 m/s. Particles are observed to circulate in both the horizontal and vertical directions. The period of horizontal circulation is short and is in the order of seconds, whereas that of the vertical circulation takes tens of seconds and often consists of lots of higher frequency fluctuations. There is a dominant solids motion in the tangential direction at all impeller speeds with the maximum tangential velocity 2.2-5.3 times that of the maximum axial and radial velocities. The maximum values of the three velocity components increase with increasing impeller speed, but the ratios of the maximum velocity to the tip speed decreases with increasing impeller speed, suggesting a rate-dependent behaviour. The particle flow pattern shows the presence of swirling flows at a position depending on the impeller speed. The results also suggest the existence of an optimal impeller speed that gives the best macroscopic mixing characterised by the vertical solids circulation. 相似文献
70.
An experimental study has been carried out on the solids motion in a conical frustum-shaped vertical high shear mixer granulator by using the positron emission particle tracking (PEPT) technique. The mixer granulator has a vertical shaft, to which four sets of impellers are attached at different elevations. The shaft is operated at 3.9 Hz, 4.9 Hz and 5.8 Hz, which corresponded to the top impeller tip speed of 2.8, 3.5 and 4.1 m/s. The motion of calcium carbonate particles with and without a liquid binder is evaluated. Particles are observed to circulate in both the horizontal and vertical directions. The macroscopic solids circulation in the vertical direction reduces after adding the binder. There is a dominant solids motion in the tangential direction under both the dry and wet conditions with the maximum tangential velocity of 2.2 to 12.6 times that of the maximum axial and radial velocities. No obvious change is observed in the average axial and radial velocities when the impeller speed is changed under both dry and wet conditions, while the ratio of the maximum tangential velocity to the tip speed decreases with increasing impeller speed, suggesting a velocity-dependent behaviour. The three velocity components decrease in the magnitude after adding the binder at all tested agitation speeds except for the tangential velocity at a shaft speed of 3.9 Hz. The main difference between the dry and wet operations is that the decrease of tangential velocity in the near-wall zone under the dry condition is not observed under the wet condition. 相似文献