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1.
Martynov S Kostson E Saffari N Stride E 《The Journal of the Acoustical Society of America》2011,130(5):2700-2708
There is increasing demand for accurate characterization of the in vivo behavior of microbubble agents used for ultrasound imaging and therapy. This study examines bubble-vessel interaction, in particular the propagation of disturbances along the vessel wall. Finite element simulations of a 3 μm radius microbubble suspended in a viscous liquid and enclosed in a 4 μm radius elastic vessel were performed, and the results compared with existing analytical results for wave propagation in elastic liquid-filled tubes. The vessel wall was shown to have a significant effect upon the amplitude of bubble oscillation and hence acoustic radiation from it, as well as distension of the vessel wall. It was found that the most important factor was the ratio of the excitation frequency to the natural "ring" frequency of the vessel which in turn depends upon its dimensions and mechanical properties. As this ratio increases, the motion of the vessel wall becomes increasingly localized to the site of the bubble. It was also shown that the validity of the results obtained using the applied model of vessel elasticity is limited to frequencies below the ring frequency, and this should be taken into account in the development of protocols for ultrasound safety and/or therapeutic procedures. 相似文献
2.
Mozhgan Khorasani-Motlagh Meissam Noroozifar Jilla Saffari Hamid Reza Khavasi 《Journal of chemical crystallography》2011,41(5):625-629
Abstract
Molecular structure of the second polymorph of [Fe(OEP)(DicydH)], where OEP is the dianion of octaethylporphyrin and DicydH = monoanion of 1,4-phenyldicyanamide, was determined by single-crystal X-ray diffraction. Fe(III) atom is five-coordinate to four N atoms of the porphyrin ring and to one nitrogen atom of DicydH. The compound is characterized by an average Fe–Np bond length of 2.057 ?. The Fe–Nax bond distance is 1.969(6) ?. Crystal data: crystal system, orthorhombic, a = 15.048(2), b = 17.515(3), c = 29.440(4) ?, space group, Pcab, V = 7759(2) ?3, Z = 8. 相似文献3.
Konkala Karnakar Jilla Shankar Sabbavarapu Narayana Murthy Yadavalli Venkata Durga Nageswar 《Helvetica chimica acta》2011,94(5):875-880
Various phenyl and p‐tolyl allyl sulfone derivatives were prepared stereoselectively by reacting Baylis? Hillman acetates with sodium 4‐R‐benzenesulfinate (R=H, Me) in H2O. The reaction was very efficient in providing the corresponding sulfone derivatives in good to excellent yields (Table). 相似文献
4.
In this paper we have considered a red-shift based linear correction in derivative of action in the context of vacuum f (R) gravity. Here we have found out that the linear correction may describe the late time acceleration which is appeared by
SuperNovae Ia with no need of dark energy. Also we have calculated the asymptotic action for the desired correction. The value
of all solutions may reduce to de’ Sitter universe in the absence of correction term. 相似文献
5.
The investigation of
norm Bernstein inequalities
for polynomials with unimodular coefficients, leads to unexpected results. Some phenomena here upset our intuition. This
paper closely revisits the ultraflat polynomials whose existence was conjectured by Littlewood in 1966 and proved by Kahane
in 1980. A major role in this study is also played by arbitrary ultraflat polynomials, that is, including those that are
not necessarily obtained by variations or refinements of Kahane's method. 相似文献
6.
Khorasani-Motlagh M Safari N Noroozifar M Saffari J Biabani M Rebouças JS Patrick BO 《Inorganic chemistry》2005,44(22):7762-7769
Three new verdoheme analogues with weakly coordinating anions, [OEOPFe(II)X], where OEOP is the monoanion of octaethyloxoporphyrin and X = PF(6), ClO(4), and BF(4), have been synthesized and characterized by spectroscopic methods. (1)H NMR spectroscopy reveals that the [OEOPFe(II)X] species are paramagnetic, and the iron is five-coordinate (S = 2). The oxidation of [OEOPFe(II)PF(6)] with dioxygen yields [(OEOPFe)(2)O](PF(6))(2). The structure of (mu-oxo)bis[(octaethyloxoporphinato)iron(III)] has been determined by X-ray diffraction analysis. The eight Fe-N bond distances have an average value of 2.077(3) Angstroms. The oxygen atom sits on the inversion center, and the average axial Fe-O bond length is 1.756(3) Angstroms. The average displacement of the iron(III) atom from the mean porphinato core is 0.60 Angstroms. Crystal data: crystal system, monoclinic; a = 8.7114(10) Angstroms; b = 26.102(4) Angstroms; c = 15.8323(14) Angstroms; beta = 104.134(6) degrees ; space group P2(1)/c; V = 3491.1(7) Angstroms (3); Z = 2; R1 = 0.0546, wR2 =0.1145 for data with I > 2sigma(I). 相似文献
7.
J. Saffari M. Khorasani-Motlagh M. Noroozifar 《Russian Journal of Inorganic Chemistry》2012,57(1):128-132
The binding of a series of nitrogen donor ligands (Piperazine (Pipz), Piperidine (Pip) and Pyrrolidine (Pyr)) to iron porphyrin,
OEPFeClO4, where OEP is octaethylporphyrin, has been characterized by electronic spectroscopy in CH2Cl2. In nonaqueous media, in the presence of a neutral ligand, the equilibria observed are: OEPFeClO4 + 2L ⇆ [OEPFeL2]+ ClO4− (β2) where the product is an ion pair and in some cases: OEPFeClO4 + L ⇆ OEPFeLClO4 (K
1), where the product may either be the six-coordinate or the five-coordinate [OEPFeL]+ ClO4− ion pair, that L denotes neutral N-donor ligands. This behavior for the nitrogen donor ligands (L = Pipz, Pip, Pyr) is confirmed
by spectrophotometric titrations data and the binding constants for the substitution reaction have been reported. 相似文献
8.
Jilla Saffari Hamid Reza Shams Davood Ghanbari Atefeh Esmaeili 《Journal of Cluster Science》2014,25(5):1225-1236
Magnetic NiFe2O4 (NiFe) nanoparticles were synthesized via a facile chemical reaction between Ni(NO3)2 and Fe(NO3)3. Different percents of NiFe nanoparticles were then added to polystyrene (PS) matrix. Nanoparticles were characterized using X-ray diffraction, scanning electron microscopy and Fourier transform infrared spectroscopy. The magnetic properties of the samples were also investigated using an alternating gradient force magnetometer. The nanoparticles exhibit ferromagnetic behaviour at room temperature, with a saturation magnetization of 20.8 emu/g and a coercivity of 99.6 Oe. Preparation of NiFe2O4 -PS nanocomposite leads to decrease in the coercivity. 相似文献
9.
Mohammad Ghalambaz Seyed Abdollah Mansouri Mehryan Kasra Ayoubi Ayoubloo Ahmad Hajjar Mohamad El Kadri Obai Younis Mohsen Saffari Pour Christopher Hulme-Smith 《Molecules (Basel, Switzerland)》2021,26(5)
Thermal energy storage units conventionally have the drawback of slow charging response. Thus, heat transfer enhancement techniques are required to reduce charging time. Using nanoadditives is a promising approach to enhance the heat transfer and energy storage response time of materials that store heat by undergoing a reversible phase change, so-called phase change materials. In the present study, a combination of such materials enhanced with the addition of nanometer-scale graphene oxide particles (called nano-enhanced phase change materials) and a layer of a copper foam is proposed to improve the thermal performance of a shell-and-tube latent heat thermal energy storage (LHTES) unit filled with capric acid. Both graphene oxide and copper nanoparticles were tested as the nanometer-scale additives. A geometrically nonuniform layer of copper foam was placed over the hot tube inside the unit. The metal foam layer can improve heat transfer with an increase of the composite thermal conductivity. However, it suppressed the natural convection flows and could reduce heat transfer in the molten regions. Thus, a metal foam layer with a nonuniform shape can maximize thermal conductivity in conduction-dominant regions and minimize its adverse impacts on natural convection flows. The heat transfer was modeled using partial differential equations for conservations of momentum and heat. The finite element method was used to solve the partial differential equations. A backward differential formula was used to control the accuracy and convergence of the solution automatically. Mesh adaptation was applied to increase the mesh resolution at the interface between phases and improve the quality and stability of the solution. The impact of the eccentricity and porosity of the metal foam layer and the volume fraction of nanoparticles on the energy storage and the thermal performance of the LHTES unit was addressed. The layer of the metal foam notably improves the response time of the LHTES unit, and a 10% eccentricity of the porous layer toward the bottom improved the response time of the LHTES unit by 50%. The presence of nanoadditives could reduce the response time (melting time) of the LHTES unit by 12%, and copper nanoparticles were slightly better than graphene oxide particles in terms of heat transfer enhancement. The design parameters of the eccentricity, porosity, and volume fraction of nanoparticles had minimal impact on the thermal energy storage capacity of the LHTES unit, while their impact on the melting time (response time) was significant. Thus, a combination of the enhancement method could practically reduce the thermal charging time of an LHTES unit without a significant increase in its size. 相似文献
10.
Maryam Saffari Jourshari Manouchehr Mamaghani Khalil Tabatabaeian Farhad Shirini 《Journal of the Iranian Chemical Society》2012,9(1):75-80
A facile and convenient protocol was developed for the synthesis of 5-arylidene-2-imino-4-thiazolidinones using solid basic catalyst immobilized onto supported ionic liquid-like phase (SILLP) in high yields (80?C95%). The X-ray analysis of the representative compound established the Z configuration of the product at the chiral axis. 相似文献