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81.
Production of fibroin nanopowder through electrospraying 总被引:1,自引:0,他引:1
Fibroin is a biomaterial and in the powder form, has found applications such as food and cosmetic additive as well as drug
delivery. Various methods have been employed to produce fibroin powder with different particle size range. In this study,
a novel and original application of electrospraying technique capable of producing fibroin nanopowder is presented. Our technique
is based on electrospraying of dilute fibroin solution in formic acid. Moreover, the effect of variables in electrospraying,
namely, concentration of fibroin solution, voltage, feed rate, and needle–collector distance, on average particle size of
fibroin nanopowder has been studied. The result of this study showed that electrospraying is capable of producing fibroin
nanopowder with average particle size as low as 80 nm. In fact in comparison to other methods reported in the literature,
electrospraying alongside with the precipitation method produce fibroin nanopowder with the lowest particle size. However,
nanopowder obtained through electrospraying technique enjoys a more uniform spherical shape and size. As far as the variables
are concerned, it was ascertained that lower concentrations, lower feed rates and longer needle–collector distances lead to
a decrease in the average particle size of fibroin nanopowder. Increasing voltage up to 20 kV decreases the particle size;
but with higher voltages the average particle size increases. FT-IR and XRD studies showed that the fibroin nanopowder has
a β-sheets structure, similar to fibroin filaments but with a lower crystallinity index. 相似文献
82.
A new high efficient and green protocol for the preparation of dihydropyrimido[4,5‐b]quinolinetrione derivatives using magnetically solid acid catalyst was presented. High performance solid acid catalyst was prepared through a three‐step reaction. Firstly, CoFe2O4 nano particles were synthesized using co‐precipitation method. In second step, CoFe2O4 nano particles were coated with SiO2 shell through treatment with tetraethyl orthosilicate (CoFe2O4@SiO2). Finaly, CoFe2O4@SiO2 was modified with polyphosphoric acid (CoFe2O4@SiO2/PPA) in a simple manner. Green reusable catalyst was characterized in details using FTIR, VSM, TEM, FESEM, EDX and used as catalyst for the synthesis of dihydropyrimido[4,5‐b]quinolinetrione derivatives. Reaction was performed under ultrasonic irradiation as green, effective and mild conditions and products were achieved in high to excellent yields. Green and eco‐friendly conditions, short reaction times with high yield of products in addition to easy workup are some merits of presented method. 相似文献
83.
Afshin Moradi 《Photonics and Nanostructures》2013,11(1):85-88
Propagation of surface plasmon–polariton modes in metallic single-walled carbon nanotubes is investigated within the framework of the classical electrodynamics. Electronic excitations on the nanotube's surface are modeled by an infinitesimally thin layer of free-electron gas which is described by means of the linearized hydrodynamic theory. General expression of surface modes dispersion is obtained by solving Maxwell and hydrodynamic equations with appropriate boundary conditions. It is shown that the system generally disallows the separation of the transverse electric (TE) modes and transverse magnetic (TM) modes, except for the case of modes with no angular dependence. 相似文献
84.
Hydrogen peroxide/MoO3, as an efficient and clean oxidizing system was used to afford diasteroselective oxidative cyclization of bisnaphthols to spirans in ethanol at 60 °C with high yields. Bisnaphthols were prepared by the reaction of a series of aldehydes and 2-naphthol in the presence of a catalytic amount of H3[P(Mo3O10)4].nH2O (HPa) in refluxing dichloromethane. 相似文献
85.
Arabali Vahid Karimi-Maleh Hassan Beitollahi Hadi Moradi Reza Ebrahimi Mahmoud Ahmar Hamid 《Ionics》2015,21(4):1153-1161
Ionics - In this study, a carbon paste electrode (CPE) was chemically modified with Pt/carbon nanotubes (CNTs) nanocomposite and 8,9-dihydroxy-7-methyl-12H-benzothiazolo [2,3-b] quinazolin-12-one... 相似文献
86.
87.
88.
Somayeh Moradi 《代数通讯》2020,48(6):2699-2712
AbstractThe present work is concerned with characterizing some algebraic invariants of edge ideals of hypergraphs. To this aim, first, we introduce some kinds of combinatorial invariants similar to matching numbers for hypergraphs. Then we compare them to each other and to previously existing ones. These invariants are used for characterizing or bounding some algebraic invariants of edge ideals of hypergraphs such as graded Betti numbers, projective dimension and Castelnouvo–Mumford regularity.Communicated by Jason P. Bell 相似文献
89.
Hamid Reza Moradi Mohsen Erfanian Omidvar Muhammad Adil Khan Kazimierz Nikodem 《Aequationes Mathematicae》2018,92(1):25-37
In this paper we use basic properties of strongly convex functions to obtain new inequalities including Jensen type and Jensen–Mercer type inequalities. Applications for special means are pointed out as well. We also give a Jensen’s operator inequality for strongly convex functions. As a corollary, we improve the Hölder-McCarthy inequality under suitable conditions. More precisely we show that if \(Sp\left( A \right) \subset \left( 1,\infty \right) \), then and if \(Sp\left( A \right) \subset \left( 0,1 \right) \), then for each positive operator A and \(x\in \mathcal {H}\) with \(\left\| x \right\| =1\).
相似文献
$$\begin{aligned} {{\left\langle Ax,x \right\rangle }^{r}}\le \left\langle {{A}^{r}}x,x \right\rangle -\frac{{{r}^{2}}-r}{2}\left( \left\langle {{A}^{2}}x,x \right\rangle -{{\left\langle Ax,x \right\rangle }^{2}} \right) ,\quad r\ge 2 \end{aligned}$$
$$\begin{aligned} \left\langle {{A}^{r}}x,x \right\rangle \le {{\left\langle Ax,x \right\rangle }^{r}}+\frac{r-{{r}^{2}}}{2}\left( {{\left\langle Ax,x \right\rangle }^{2}}-\left\langle {{A}^{2}}x,x \right\rangle \right) ,\quad 0<r<1 \end{aligned}$$
90.
A simple, rapid, and efficient method, based on surfactant assisted dispersive liquid-liquid microextraction (SA-DLLME), followed by high performance liquid chromatography (HPLC) has been developed for the extraction and determination of chlorophenols as model compounds in environmental water samples. A conventional cationic surfactant called cethyltrimethyl ammonium bromide (CTAB) was used as a disperser agent in the proposed approach. Thirty-five microliter of 1-octanol as an extraction solvent was injected rapidly into 11 mL aqueous sample containing 0.09 mmol L−1 of CTAB, the mixture was then shaken for 3 min to disperse the organic phase. Having the extraction procedure been completed, the mixture was centrifuged and 20 μL of collected phase was injected into HPLC for subsequent analysis. Some parameters such as the type and volume of the extraction solvent, the type and concentration of surfactant, pH, ionic strength, shaking time, extraction temperature and centrifugation time were optimized. The preconcentration factors (PFs) in a range of 187-353 were obtained under the optimum conditions. The linear range, detection limit (S/N = 3), and precision (n = 5) were 0.2-200, 0.1 μg L−1, and 4.7-6.9%, respectively. Tap water, sea water and mineral water samples were successfully analyzed for the existence of chlorophenols using the proposed method. 相似文献