排序方式: 共有161条查询结果,搜索用时 15 毫秒
21.
Hamidreza Bojari Azim Malekzadeh Mahnaz Ghiasi Ahmad Gholizadeh Ramin Azargohar Ajay Kumar Dalai 《Crystal Research and Technology》2013,48(6):355-362
Lanthanum oxide nanoparticles were synthesized via thermal decomposition method of the lanthanum nitrate in the presence of citric acid or starch as emulsifier. The effects of emulsifier and calcination temperature were investigated on the phase transformation and particle size distribution of the products. La2O3 nanoparticles were synthesized by drying lanthanum precursor and emulsifier solution, followed by calcination process at 600 and 900°C, respectively. Products were characterized by Fourier Transform Infrared (FT‐IR) spectroscopy, X‐ray diffraction (XRD), thermal analysis (TG/DTA) and nitrogen adsorption method (porous characteristics). The morphology of the samples analyzed using scanning electron microscopy (SEM). Average crystallite size of the products was calculated by XRD data and average particle size was measured from the TEM micrographs. Lanthanum dioxycarbonate in different forms of the tetragonal and monoclinic is crystallized in the presence of citric acid and starch during the calcination at 600°C, respectively. The hexagonal structure, however, is detected as the only crystalline phase formed by calcination at 900°C. 相似文献
22.
Hamidreza Enshaei Brenda G. Molina Luis J. del Valle Francesc Estrany Carme Arnan Jordi Puiggalí Núria Saperas Carlos Alemn 《Macromolecular bioscience》2019,19(8)
Ambroxol is a pharmacological chaperone (PC) for Gaucher disease that increases lysosomal activity of misfolded β‐glucocerebrosidase (GCase) while displaying a safe toxicological profile. In this work, different poly(ε‐caprolactone) (PCL)‐based systems are developed to regulate the sustained release of small polar drugs in physiological environments. For this purpose, ambroxol is selected as test case since the encapsulation and release of PCs using polymeric scaffolds have not been explored yet. More specifically, ambroxol is successfully loaded in electrospun PCL microfibers, which are subsequently coated with additional PCL layers using dip‐coating or spin‐coating. The time needed to achieve 80% release of loaded ambroxol increases from ≈15 min for uncoated fibrous scaffolds to 3 days and 1 week for dip‐coated and spin‐coated systems, respectively. Furthermore, it is proven that the released drug maintains its bioactivity, protecting GCase against induced thermal denaturation. 相似文献
23.
Karimi-Alavijeh H Baghban MA Parsanasab GM Sarailou E Gharavi A Javadpour S 《Optics letters》2008,33(18):2152-2154
We have fabricated in-plane slanted gratings on azo-functionalized polymeric films using a fast, direct-writing method. By properly adjusting the resonance, these gratings can be used as 90 degrees integrated reflectors and add/drop filters in the plane of the film. We have produced an attenuation of 14.8 dB at 1560.2 nm with a FWHM of 6.47 nm. Also, a signal of 1548 nm wavelength was added to the output from a different direction. Any light shifted from the resonance will pass through the filter undisturbed. 相似文献
24.
Determination of concentration of major elements such as Ca, Si, Al, and Fe in cement is very important for quality control during its production, correct classification according to the existing standards, and thus for appropriate use in the construction industry. For this purpose, neutron activation analysis is very suitable. In this preliminary theoretical work, the irradiation and consecutive measurement of the percentage of the constituent elements in different cement samples were done using MCNPX with γ-ray spectra as the output. Specific peaks of Ca, Si, Al, and Fe obtained from these spectra were used as input for artificial neural network (18 of them for training and 8 for testing) resulting in the determination of each element in the given sample. The mean absolute errors of the results are less than 0.4%, which is very promising for the future experimental work where the uncertainties are usually one order higher. 相似文献
25.
Hassan Keypour Reza Azadbakht Hadi Amiri Rudbari Alireza Heydarinekoo Hamidreza Khavasi 《Transition Metal Chemistry》2009,34(8):835-839
Three new potentially hexadentate N4O2 Schiff-base ligands (H2L1, H2L2 and H2L3) were prepared from the reaction of the polyamines N,N′-bis(2-aminophenyl)-1,2-ethanediamine (L1), N,N′-bis(2-aminophenyl)-1,3-propanediamine (L2) and N,N′-bis(2-aminophenyl)-1,4-butanediamine (L3), respectively with salicylaldehyde. Reaction of the Schiff bases with Ni(II) salts in the presence of N(Et)3 gave the neutral complexes [NiL4], [NiL5] and [NiL6]. Ni(II) complexes of the polyamines were also prepared. One of complexes [Ni(L1)(MeCN)2](ClO4)2·MeCN has been characterized through X-ray diffraction methods. 相似文献
26.
Ali Badiee Mahmoud R. Jaafari Ali Khamesipour Afshin Samiei Dina Soroush Masoumeh Tavassoti Kheiri Farzaneh Barkhordari W. Robert McMaster Fereidoun Mahboudi 《Colloids and surfaces. B, Biointerfaces》2009,74(1):37-44
Development of new generation vaccines requires adjuvants to elicit the type and intensity of immune response needed for protection. Liposomes have been shown to be an effective adjuvant formulation. In this study, the role of liposome bilayer composition with different phase transition temperature (Tc) to induce a T helper 1 (Th1) type of immune response and protection against leishmaniasis in BALB/c mice was assessed. Liposome formulations with different bilayer compositions consisting of egg phosphatidylcholine (EPC, Tc < 0 °C), dipalmitoylphosphatidylcholine (DPPC, Tc 41 °C), or distearoylphosphatidylcholine (DSPC, Tc 54 °C) were prepared. All liposomes were contained rgp63 as a recombinant antigen and used to immunize mice subcutaneously 3 times in 3-week intervals. Evaluation of lesion development and splenic parasite burden after challenge with L. major, evaluation of Th1 cytokine (IFN-γ) and Th2 cytokine (IL-4), and titration of IgG isotypes were carried out to assess the type of generated immune response and extent of protection. The results indicated the generated immune response in mice was influenced by the bilayer composition of liposomes, so that mice immunized with liposomes consisting of EPC induced a Th2 type of immune response while liposome consisting of DPPC or DSPC induced Th1 type of immune response. It seems that liposomes prepared with higher Tm phospholipids are suitable formulation to induce Th1 type of immune response and protection, and so might be used for further investigations to develop an effective vaccine against leishmaniasis. 相似文献
27.
This paper presents a multiobjective evolutionary algorithm (MOEA) capable of handling stochastic objective functions. We
extend a previously developed approach to solve multiple objective optimization problems in deterministic environments by
incorporating a stochastic nondomination-based solution ranking procedure. In this study, concepts of stochastic dominance
and significant dominance are introduced in order to better discriminate among competing solutions. The MOEA is applied to
a number of published test problems to assess its robustness and to evaluate its performance relative to NSGA-II. Moreover,
a new stopping criterion is proposed, which is based on the convergence velocity of any MOEA to the true Pareto optimal front,
even if the exact location of the true front is unknown. This stopping criterion is especially useful in real-world problems,
where finding an appropriate point to terminate the search is crucial. 相似文献
28.
Hamidreza?SalimiEmail author Karl-Heinz?Wolf Johannes?Bruining 《Transport in Porous Media》2012,91(2):391-422
This article deals with developing a solution approach, called the non-isothermal negative saturation (NegSat) solution approach.
The NegSat solution approach solves efficiently any non-isothermal compositional flow problem that involves phase disappearance,
phase appearance, and phase transition. The advantage of the solution approach is that it circumvents using different equations
for single-phase and two-phase regions and the ensuing unstable procedure. This paper shows that the NegSat solution approach
can also be used for non-isothermal systems. The NegSat solution approach can be implemented efficiently in numerical simulators
to tackle modeling issues for mixed CO2–water injection in geothermal reservoirs, thermal recovery processes, and for multicontact miscible and immiscible gas injection
in oil reservoirs. We illustrate the approach by way of example to cold mixed CO2–water injection in a 1D geothermal reservoir. The solution is compared with an analytical solution obtained with the wave-curve
method (method of characteristics) and shows excellent agreement. A complete set of simulations is carried out, which identifies
six bifurcations. The two main bifurcations are (1) when the most downstream compositional wave is replaced by a compositional
shock and (2) when an extra Buckley–Leverett rarefaction appears. The plot of the useful energy (exergy) versus the CO2 storage capacity shows a Z-shape. The top horizontal part represents a branch of high exergy recovery/relatively lower storage capacity, whereas the
bottom part represents a branch of lower exergy recovery/higher storage capacity. 相似文献
29.
Amin Heshmati-Moulai Hamidreza Simchi Mahdi Esmaeilzadeh 《The European Physical Journal B - Condensed Matter and Complex Systems》2017,90(7):128
We study perfect valley polarization in a molybdenum disulfide (MoS2) nanoribbon monolayer using two bands Hamiltonian model and non-equilibrium Green’s function method. The device consists of a one-dimensional quantum wire of MoS2 monolayer sandwiched between two zigzag MoS2 nanoribbons such that the sites A and B of the honeycomb lattice are constructed by the molecular orbital of Mo atoms, only. Spin-valley coupling is seen in energy dispersion curve due to the inversion asymmetry and time-reversal symmetry. Although, the time reversal symmetry is broken by applying an external magnetic field, the valley polarization is very small. A valley polarization equal to 46% can be achieved using an exchange field of 0.13 eV. It is shown that a particular spin-valley combination with perfect valley polarization can be selected based on a given set of exchange field and gate voltage as input parameters. Therefore, the valley polarization can be detected by detecting the spin degree of freedom. 相似文献
30.
Hamidreza Shirvani-Mahdavi Seyede Zahra Shoursheini Hamid Gholami Ziba Dini-Torkamani Sare Ghahari-Korani 《Applied physics. B, Lasers and optics》2014,117(3):823-832
Identification and concentration measurement of constituent elements of a metallic alloy is demonstrated by calibration-free laser-induced breakdown spectroscopy (CF-LIBS) according to a special peak intensity-based model and considering the self-absorption effect. In this procedure, which is based on the line pair ratio method, the effect of line widths, though needs to be theoretically considered, may be approximately ignored. This is mainly true for the multiplet lines, but this property, in the case of some generic spectral lines in a measured spectrum, can be sometimes regarded. Initially, the optical penetration depth and therefrom self-absorption coefficient of each selected spectral line is calculated using the experimental (self-absorbed) intensity of the line. Then, the true (non-self-absorbed) intensity, which is basis of the conventional CF-LIBS calculation, is obtained through a recursive algorithm implemented by the MATLAB programming. In the experimental examination, the recorded spectrum reflects that the metallic alloy is consisted of gold, copper and silver. The concentration of elements is calculated with and without regarding self-absorption correction using 27 trios of spectral lines related to the elements. The average concentrations signify that the measurement error relative to the certified value for the concentration of the gold is modified from 3.56 % in the normal way to 0.34 % after applying self-absorption correction. 相似文献