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961.
Asymmetrical-flow field flow fractionation (AFFF) separates constituents based on hydrodynamic size and is emerging as a powerful
tool for obtaining high-resolution information on the size, molecular weight, composition, and stability of nanoscale particles
in liquid media. We employ a customized AFFF system combining on-line detectors for multi-angle light scattering, dynamic
light scattering, and UV–Vis absorption. Our objective is to develop optimized measurement protocols for the characterization
of gold nanoparticles (GNPs), which are widely utilized in biomedical research and other nanotechnology applications. Experimental
conditions have been optimized by controlling key parameters, including injection volume and solids concentration, mobile
phase composition, membrane type and pore size, and ratio of channel-to-cross-flow rates. Individual citrate-stabilized GNP
components (nominally 10, 20, 30, 40, and 60 nm) and GNPs functionalized with polyethylene glycol were separated from multicomponent
GNP mixtures by AFFF and subsequently characterized. We discuss the effects due to variations in measurement parameters and
GNP surface modification on observed retention, recovery, and peak resolution. 相似文献
962.
We propose three-dimensional (3D) optical microscopy using axially distributed image sensing. In the proposed method, the micro-objects are optically magnified and their axially distributed images are recorded by moving the image sensor along a common optical axis. The 3D volumetric images are generated from the recorded axial image set using a computational reconstruction algorithm based on ray backprojection. Preliminary experimental results are presented. To the best of our knowledge, this is the first report on 3D optical microscopy using axially distributed sensing. 相似文献
963.
Here we describe an anion excluding ion‐permeable membrane, which we evaluate on an O2‐electroreducing cathode poised at a strongly oxidizing potential, near the reversible potential of the O2/H2O half cell. The bioelectrocatalyst of the O2 cathode consists of the cross‐linked electrostatic adduct of a polycationic redox hydrogel and bilirubin oxidase (BOD), a polyanion at neutral at pH 7.3. If an uncured Nafion dispersion is applied on this bioelectrocatalyst, the polyanionic Nafion displaces the BOD in the electrostatic adduct, de‐wiring the BOD. We show here that insertion of a polycationic poly(acrylamide‐co‐vinylimidazole) (PAA‐PVI) between the bioelectrocatalyst and the Nafion prevents the dewiring of BOD. The resulting bi‐layer membrane effectively excludes the urate, thiocyanate and NADH anions. 相似文献
964.
Sung Hee Yoon Sun Ok Yun Jung Yong Park Hee Yeun Won Eun-Kyung Kim Hyun-Jung Sohn Hyun-Il Cho Tai-Gyu Kim 《Experimental & molecular medicine》2009,41(3):161-170
Increasing importance is being given to the stimulation of Th1 response in cancer immunotherapy because its presence can shift the direction of adaptive immune responses toward protective immunity. Based on chemokine receptor expression, CXCR3+CCR4-CD4+ T cells as Th1-type cells were investigated its capacity in monocyte-derived dendritic cell (DC) maturation and polarization, and induction of antigen specific cytotoxic T lymphocytes (CTL) in vitro. The levels of IL-4, IL-5 and IL-10 were decreased to the basal level compared with high production of IFN-γ, TNF-α, and IL-2 in CXCR3+CCR4-CD4+ T cells stimulated with anti-CD3 and anti-CD28 antibodies. Co-incubation of activated CD4+ or CXCR3+CCR4-CD4+ T cells with DC (CD4+/DC or CXCR3+CD4+/DC, respectively) particularly up-regulated IL-12 and CD80 expression compared with DC matured with TNF-α and LPS (mDC). Although there was no significant difference between the effects of the CXCR3+CCR4-CD4+ and CD4+ T cells on DC phenotype expression, CXCR3+CD4+/DC in CTL culture were able to expand number of CD8+ T cells and increased frequencies of IFN-γ secreting cells and overall cytolytic activity against tumor antigen WT-1. These results demonstrated that the selective addition of CXCR3+CCR4-CD4+ T cells to CTL cultures could enhance the induction of CTLs by DC in vitro, and implicated on a novel strategy for adoptive T cell therapy. 相似文献
965.
Kyungtae Kim Sung Chun Cho Anthony Cova Ik Soon Jang Sang Chul Park 《Experimental & molecular medicine》2009,41(5):334-340
The effects of glucagon and epinephrine on gluconeogenesis in young (4 month) and old (24 month) Fisher 344 rat hepatocytes were compared. In contrast to glucagon, which had a similar effect on gluconeogenesis in both young and old cells, epinephrine caused a smaller increase in gluconeogenesis in old rat hepatocytes than in young hepatocytes. β2 adrenergic receptor (β2-AR) expression slightly decreased in aged rat liver, and there were differences between young and old hepatocytes in their patterns of G protein coupled receptor kinases, which are involved in the activation of β2-AR receptor signal desensitization. The major isoform of the kinase changed from GRK2 to GRK3 and the expression of β-arrestin, which is recruited by the phosphorylated β2-AR for internalization and degradation, increased in aged rat liver. GRK3 overexpression also decreased the glucose output from young rat hepatocytes. We conclude that an age-associated reduction in epinephrine-induced gluconeogenesis occurs through the epinephrine receptor desensitizing system. 相似文献
966.
Dong Wook Shin Ji-Won Choi Won-Kook Choi Yong Soo Cho Seok-Jin Yoon 《Electrochemistry communications》2009,11(3):695-698
The influence of Sn substitution in LiMn2O4 thin films as a cathode has been studied via solution deposition to improve the electrochemical performance of thin film lithium batteries. LiSn0.025Mn1.95O4 thin films showed the most promising performance, i.e. a high capacity retention of 77% at 10 C after the 500th cycle, due to the increased average Mn valence state. The thin films of LiSnx/2Mn2?xO4 (x ? 0.10) showed significant precipitation of SnO2 and SnO after the cycling evaluation. 相似文献
967.
Soyoung Jung Won Cho Hee Jung Lee Moonhyun Oh Prof. Dr. 《Angewandte Chemie (International ed. in English)》2009,48(8):1459-1462
This template will self‐destruct : A unique particle‐growth mechanism involves growth of new coordination polymers on the surface of initially formed hexagonal blocks and concomitant dissolution of the blocks to form hexagonal tubes (see scheme and scanning electron, optical, and fluorescence microscopy images). Calcination of the tubes yields ZnO particles of the same shape.
968.
Hee Jung Choi Hwan Sun Cho Sang Cheol Han Myung Ho Hyun 《Journal of separation science》2009,32(4):536-541
A residual silanol group‐protecting chiral stationary phase (CSP) based on optically active (3,3′‐diphenyl‐1,1′‐binaphthyl)‐20‐crown‐6 was successfully applied to the resolution of fluoroquinolone compounds including gemifloxacin mesylate. The chiral recognition ability of the residual silanol group‐protecting CSP was generally greater than that of the residual silanol group‐containing CSP. From these results, it was concluded that the simple protection of the residual silanol groups of the latter CSP with lipophilic n‐octyl groups can improve its chiral recognition ability for the resolution of racemic fluoroquinolone compounds. The chromatographic resolution behaviors were investigated as a function of the content and type of organic and acidic modifiers and the ammonium acetate concentration in aqueous mobile phase and the column temperature. Especially, the addition of ammonium acetate to the mobile phase was found to be a quite effective means of reducing the enantiomer retentions without sacrificing the chiral recognition efficiency of the CSP. 相似文献
969.
Dong Hyun Cho 《Czechoslovak Mathematical Journal》2009,59(2):431-452
Let C[0, T] denote the space of real-valued continuous functions on the interval [0, T] with an analogue w
ϕ of Wiener measure and for a partition 0 = t
0 < t
1 < ... < t
n
< t
n+1 = T of [0, T], let X
n
: C[0, T] → ℝ
n+1 and X
n+1: C[0, T] → ℝ
n+2 be given by X
n
(x) = (x(t
0), x(t
1), ..., x(t
n
)) and X
n+1(x) = (x(t
0), x(t
1), ..., x(t
n+1)), respectively.
In this paper, using a simple formula for the conditional w
ϕ-integral of functions on C[0, T] with the conditioning function X
n+1, we derive a simple formula for the conditional w
ϕ-integral of the functions with the conditioning function X
n
. As applications of the formula with the function X
n
, we evaluate the conditional w
ϕ-integral of the functions of the form F
m
(x) = ∫0
T
(x(t))
m
for x ∈ C[0, T] and for any positive integer m. Moreover, with the conditioning X
n
, we evaluate the conditional w
ϕ-integral of the functions in a Banach algebra
which is an analogue of the Cameron and Storvick’s Banach algebra
. Finally, we derive the conditional analytic Feynman w
ϕ-integrals of the functions in
.
相似文献
970.
Atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS), and Fourier transform infrared reflection absorption spectroscopy (FT-IRRAS) were employed to understand the size, composition, and conformation of lithographic patterns composed of peptide molecules. GaAs surfaces were patterned by microcontact printing (microCP) and dip-pen nanolithography (DPN) using a peptide sequence composed of 15 amino acids. The detailed surface evaluation showed that the patterns have similar chemical compositions but differ in the bonding among the molecules anchored on the GaAs substrate. Both types of patterns were crystalline-like in nature. The features created by DPN exhibited interchain hydrogen bonding, while the ones generated by microCP displayed non-hydrogen bonding. The differences in the lithographic structures can be utilized in future biorecognition experiments that take advantage of the electronic properties of the GaAs substrate and the tunable behavior of the covalently anchored biomolecules on the surface. 相似文献