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排序方式: 共有142条查询结果,搜索用时 25 毫秒
21.
Voislav Blagojevic Sopeia N. Samad Laura Banu Michael C. Thomas Stephen J. Blanksby Diethard K. Bohme 《International journal of mass spectrometry》2011,299(2-3):125-130
Results of mass spectrometric studies are reported for the collisional dissociation of Group XI (Cu, Ag, Au) metal ion complexes with fatty acids (palmitic, oleic, linoleic and α-linolenic) and glycerolipids. Remarkably, the formation of M2H+ ions (M = Cu, Ag) is observed as a dissociation product of the ion complexes containing more than one metal cation and only if the lipid in the complex contains a double bond. Ag2H+ is formed as the main dissociation channel for all three of the fatty acids containing double bonds that were investigated while Cu2H+ is formed with one of the fatty acids and, although abundant, is not the dominant dissociation channel. Also, Cu(I) and Ag(I) ion complexes were observed with glycerolipids (including triacylglycerols and glycerophospholipids) containing either saturated or unsaturated fatty acid substituents. Interestingly, Ag2H+ ion is formed in a major fragmentation channel with the lipids that are able to form the complex with two metal cations (triacylglycerols and glycerophosphoglycerols), while lipids containing a fixed positive charge (glycerophospocholines) complex only with a single metal cation. The formation of Ag2H+ ion is a significant dissociation channel from the complex ion [Ag2(L–H)]+ where L = Glycerophospholipid (GP) (18:1/18:1). Cu(I) also forms complexes of two metal cations with glycerophospholipids but these do not produce Cu2H+ upon dissociation. Rather organic fragments, not containing Cu(I), are formed, perhaps due to different interactions of these metal cations with lipids resulting from the much smaller ionic radius of Cu(I) compared to Ag(I). 相似文献
22.
R. A. Brown Razak Abd. Samad Bin Yahya 《Journal of Polymer Science.Polymer Physics》1985,23(3):451-459
Measurements of thermal diffusivities of peroxide-cured and sulfur-cured rubbers, over the range 0–100°C and 0–75 phr of carbon, are described. They are based on the asymptotic time dependences of heating and cooling curves, recorded following quenching of the samples into baths at various temperatures. The diffusivities are shown to depend linearly on both temperature and carbon content, to reasonable accuracies over the ranges studied. Some theory bearing on measurement techniques is presented. 相似文献
23.
Two different sets of collective-coordinate equations for solitary solutions of nonlinear Klein–Gordon (NKG) model are introduced. The collective-coordinate equations are derived using different approaches for adding the inhomogeneities as external potentials to the soliton equation of motion. The interaction of the NKG field with a local inhomogeneity like a delta function potential wall or a delta-function potential well is investigated using the presented collective-coordinate equations, and the results of the two different models are compared. Most of the characters of the interaction are derived analytically. The analytical results are also compared to the results of numerical simulations. 相似文献
24.
Maryam Mohebbi Peyman Salehi Morteza Bararjanian Samad N. Ebrahimi 《Journal of the Iranian Chemical Society》2018,15(1):47-53
In this paper, synthesis of two derivatives of noscapine and their application as organocatalysts in the asymmetric addition of diethylzinc to aromatic aldehydes is reported. The first catalyst (2) was synthesized by the reduction of lactone ring of noscapine to form the corresponding diol, and the second one (3) was prepared by tert-butyl dimethyl silylation of the primary hydroxyl group of 2. Excellent yields and high ees up to 95% were obtained by using 3 as the catalyst. To the best of our knowledge, this is the first report on the application of lactone ring opened noscapinoid compounds as organocatalysts in asymmetric reactions. 相似文献
25.
Shuo Chen Lijuan Wang Lei Yang Abdus Samad Rana Chuanglong He 《Macromolecular bioscience》2023,23(12):2300223
Organoid is an emerging frontier technology in the field of life science, in which pluripotent stem cells or tissue-derived differentiated/progenitor cells form 3D structures according to their multi-directional differentiation potential and self-assembly ability. Nowadays, although various types of organoids are widely investigated, their construction is still complicated in operation, uncertain in yield, and poor in reproducibility for the structure and function of native organs. Constructing a biomimetic microenvironment for stem cell proliferation and differentiation in vitro is recognized as a key to driving this field. This review reviews the recent development of engineered biomimetic microenvironments for organoids. First, the composition of the matrix for organoid culture is summarized. Then, strategies for engineering the microenvironment from biophysical, biochemical, and cellular perspectives are discussed in detail. Subsequently, the newly developed monitoring technologies are also reviewed. Finally, a brief conclusion and outlook are presented for the inspiration of future research. 相似文献
26.
Pure and 0.384% Pb2+ ions doped goethite samples were prepared in the laboratory by the coprecipitation method. The laboratory-prepared goethite samples were characterized for pH of point of zero charge (pHpzc), surface area, XRD, TG-DTA, TEM, SEM and FTIR analysis, which suggest that the Pb2+ ions are incorporated into the crystals of goethite and are also present on the surface in the hydroxylated form. Chromate adsorption studies were carried out in the concentration range 0.25-2.01 mmol L−1 at pH 3, 5 and 7, which show that maximum chromate is adsorbed at the lowest pH of 3 by both the samples of goethite. Effect of temperature on the adsorption of chromate, in the range 303-323 K, shows that the process of adsorption is endothermic in case of pure goethite and exothermic in case of Pb-doped goethite. The values of isosteric heat of adsorption were positive for pure goethite and negative for Pb-doped goethite, which are consistent with the effect of temperature on the process of adsorption. Langmuir isotherm was found applicable to the experimental data. FTIR analysis and equilibrium pH changes reveal that at pH 3 outersphere while at pH 5 and 7 innersphere complexation is the dominant mechanism for chromate adsorption by both the samples of goethite. 相似文献
27.
The Korteweg-de Vries-Burgers (KdV-Burgers) equation and modified Korteweg-de Vries-Burgers equation are derived in strongly
coupled dusty plasmas containing nonthermal ions and Boltzmann distributed electrons. It is found that solitary waves and
shock waves can be produced in this medium. The effects of important parameters such as ion nonthermal parameter, temperature,
density and velocity on the properties of shock waves and solitary waves are discussed. 相似文献
28.
The propagation of nonlinear waves in dusty plasmas with variable dust charge and two temperature ions is analyzed. By using
the reductive perturbation theory, the Kadomtsev-Petviashivili (KP) equation is derived. A Sagdeev potential has been investigated.
This potential is used to study the stability conditions for existence of solitonic solutions. Also, it is shown that a rarefactive
soliton can exist in most of the cases. The energy of the soliton has been calculated and by using the standard normal-mode
analysis a linear dispersion relation has been obtained. The effects of variable dust charge on the amplitude, width and energy
of soliton and its effects on the angular frequency of linear wave are also discussed. 相似文献
29.
Mandani Somayeh Sarbishaei Mohsen Javidan Kurosh 《International Journal of Theoretical Physics》2017,56(10):3244-3256
We have investigated the dynamics of a four-level N-type atom in cavity QED with consideration to the Kerr effect. The non-Markovianity of the system has been studied using the Breuer-Laine-Piilo (BLP) measure (N B L P ). Moreover the effects of system parameters like temperature and atom-field coupling have also been discussed. The evolution equation of the system has been derived using the time convolution-less(TCL) master equation. Some interesting behaviour of the system and their reasons are discussed.
相似文献30.
Full-Field Thermoelastic Stress Analysis of a Finite Structure Containing an Irregularly-Shaped Hole
An assessment of the structural integrity of members containing irregularly-shaped cutouts necessitates knowing the associated stresses. Stress analysis of such structures can be challenging as theoretical solutions are seldom available for finite geometries having non-simple shaped discontinuities and, like numerical methods, they require accurate knowledge of external loads. The latter are often unavailable in practice. This paper describes the ability to process load induced temperature information with an Airy stress function in real polar coordinates to determine the stresses in an isotropic linear elastic finite tensile plate containing an irregularly-shaped hole. Using polar coordinates is significant in that while a relatively simple general solution to the governing biharmonic equation is available in polar coordinates, this is seemingly not so with orthogonal curvilinear coordinates. Compared with displacement-based experimental or finite element techniques, important advantages of the present technique include not having to differentiate recorded data, or know constitutive properties or external loads. 相似文献