Size fractionation of marine sediments by pinched inlet gravitational split-flow thin fractionation and the study of size dependent PCDD/Fs concentrations from different bay areas

2005 ◽  
Vol 28 (4) ◽  
pp. 373-379 ◽  
Author(s):  
Myeong Hee Moon ◽  
Hyun-Joo Kim ◽  
Young-Ok Jung ◽  
Se-Jin Lee ◽  
Yoon-Seok Chang
Keyword(s):  
Marine Sediments ◽  
Size Fractionation ◽  
Size Dependent ◽  
Split Flow

Pinched Inlet Split Flow Thin Fractionation for Continuous Particle Fractionation:  Application to Marine Sediments for Size-Dependent Analysis of PCDD/Fs and Metals

2004 ◽  
Vol 76 (11) ◽  
pp. 3236-3243 ◽  
Author(s):  
Myeong Hee Moon ◽  
Hyun-Joo Kim ◽  
So-Yeon Kwon ◽  
Se-Jin Lee ◽  
Yoon-Seok Chang ◽  
...  
Keyword(s):  
Marine Sediments ◽  
Size Dependent ◽  
Split Flow ◽  
Particle Fractionation ◽  
Continuous Particle

scholarly journals Molecular size-fractionation during endocytosis in macrophages.

1995 ◽  
Vol 129 (4) ◽  
pp. 989-998 ◽  
Author(s):  
E P Berthiaume ◽  
C Medina ◽  
J A Swanson
Keyword(s):  
Structural Information ◽  
Fluid Phase ◽  
Molecular Size ◽  
Size Fractionation ◽  
Extracellular Medium ◽  
Mhc Molecules ◽  
Size Dependent ◽  
Class Ii Mhc ◽  
Solute Movement ◽  
Endocytic Vesicles

The sorting of macromolecules within and between membranous organelles is often directed by information contained in protein primary or secondary structure. We show here that absent such structural information, macromolecules internalized by endocytosis in macrophages can be sorted by size. After endocytosis, small solute probes of fluid-phase pinocytosis were recycled to the extracellular medium more efficiently than large solutes. Using macropinosomes pulse labeled with fluorescent dextrans, we examined the ability of organelles to exchange solute contents. Dextran exchange was optimal between organelles of similar age, and small dextrans exchanged more efficiently than large dextrans. Efferent solute movement, from lysosomes or phagolysosomes toward the plasma membrane, occurred through the same endocytic vesicles as afferent movement, toward lysosomes and this movement was solute size dependent. Remarkably, uniform mixtures of different-sized dextrans delivered into lysosomes separated into distinct organelles containing only one dextran or the other. Thus, the dynamics of endosomes and lysosomes were sufficient to segregate macromolecules by size. This intracellular size fractionation could explain how, during antigen presentation, peptides generated by lysosomal proteases recycle selectively from lysosomes to endosomes for association with class II MHC molecules.

Pinched inlet gravitational split-flow thin fractionation of airborne particles and analysis of size dependent level of PCDD/Fs

2005 ◽  
Vol 28 (11) ◽  
pp. 1231-1236 ◽  
Author(s):  
Myeong Hee Moon ◽  
Hyun-Joo Kim ◽  
Se-Jin Lee ◽  
Yoon-Seok Chang
Keyword(s):  
Airborne Particles ◽  
Size Dependent ◽  
Split Flow

Size fractionation of graphene oxide sheets assisted by circular flow and their graphene aerogels with size-dependent adsorption

RSC Advances ◽  
2016 ◽  
Vol 6 (78) ◽  
pp. 74053-74060 ◽  
Author(s):  
Shiyu Zhang ◽  
Yajun Li ◽  
Jun Sun ◽  
Jianjun Wang ◽  
Chuanxiang Qin ◽  
...  
Keyword(s):  
Graphene Oxide ◽  
Size Fractionation ◽  
Circular Flow ◽  
Size Dependent ◽  
Graphene Aerogels ◽  
Graphene Oxide Sheets

Crude GO sheets are easily separated into three size ranges, namely LGO, MGO and SGO, assisted by circular flow.

scholarly journals Size Fractionation of Fluorescent Graphene Quantum Dots Using a Cross-Flow Membrane Filtration System

Nanomaterials ◽  
2018 ◽  
Vol 8 (11) ◽  
pp. 959 ◽  
Author(s):  
Sang-Gu Yim ◽  
Yong Kim ◽  
Ye-Eun Kang ◽  
Byung Moon ◽  
Eun Jung ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Membrane Filtration ◽  
Aqueous Suspension ◽  
Graphene Quantum Dots ◽  
Cross Flow ◽  
Size Fractionation ◽  
Size Dependent ◽  
Cross Flow Filtration ◽  
Filtration System ◽  
Flow Filtration

Graphene quantum dots (GQDs) have received great attention as optical agents because of their low toxicity, stable photoluminescence (PL) in moderate pH solutions, and size-dependent optical properties. Although many synthetic routes have been proposed for producing GQD solutions, the broad size distribution in GQD solutions limits its use as an efficient optical agent. Here, we present a straightforward method for size fractionation of GQDs dispersed in water using a cross-flow filtration system and a track-etched membrane with cylindrical uniform nanopores. The GQD aqueous suspension, which primarily contained blue-emitting GQDs (B-GQDs) and green-emitting GQDs (G-GQDs), was introduced to the membrane in tangential flow and was fractionated with a constant permeate flow of about 800 L m−2 h−1 bar−1. After filtration, we observed a clear blue PL spectrum from the permeate side, which can be attributed to selective permeation of relatively small B-GQDs. The process provided a separation factor (B-GQDs/G-GQDs) of 0.74. In the cross-flow filtration system, size-dependent permeation through cylindrical nanochannels was confirmed by simulation. Our results demonstrate a feasible method facilitating size fractionation of two-dimensional nanostructures using a cross-flow membrane filtration system. Since membrane filtration is simple, cost-effective, and scalable, our approach can be applied to prepare a large amount of size-controlled GQDs required for high performance opto-electronics and bio-imaging applications.

scholarly journals Complementation between pathological prion protein subassemblies to cross existing species barriers

2019 ◽  
Author(s):  
Angélique Igel-Egalon ◽  
Florent Laferrière ◽  
Philippe Tixador ◽  
Mohammed Moudjou ◽  
Laetitia Herzog ◽  
...  
Keyword(s):  
Prion Protein ◽  
Species Concept ◽  
Structural Heterogeneity ◽  
Size Fractionation ◽  
Species Barrier ◽  
Size Dependent ◽  
Prion Strains ◽  
Insight Into ◽  
Relative Capacity ◽  
Transmission Barrier

AbstractBackgroundprion replication results from the autocatalytic templated assisted conversion of the host-encoded prion protein PrPC into misfolded, polydisperse PrPSc conformers. Structurally distinct PrPSc conformers can give rise to multiple prion strains. Within and between prion strains, the biological activity (replicative efficacy and specific infectivity) of PrPSc assemblies is size-dependent and thus reflects an intrinsic structural heterogeneity. The contribution of such PrPSc heterogeneity across species prion adaptation, - which is believed to be based on fit-adjustment between PrPSc template(s) and host PrPC -, has not been explored.Methodsto define the structural-to-fitness PrPSc landscape, we measured the relative capacity of size-fractionated PrPSc assemblies from different prion strains to cross mounting species barriers in transgenic mice expressing foreign PrPc.Resultsin the absence of a transmission barrier, the relative efficacy of the isolated PrPSc assemblies to induce the disease is superimposable to the efficacy observed in the homotypic context. However, in the presence of a transmission barrier, size fractionation overtly delays and even abrogates prion pathogenesis in both neural and extraneural, prion-permissive tissues, for reason independent of the infectivity load of the isolated assemblies. This suggests that a synergy between structurally distinct PrPSc assemblies in the inoculum is requested for crossing the species barrier. We further strengthen this hypothesis by showing that altering, by serial dilution, PrPSc assemblies content of unfractionated inocula reduce their specific infectivity in an aberrant manner, solely in the presence of a transmission barrier.Conclusionsour data support a mechanism whereby overcoming prion species barrier requires complementation between structurally distinct PrPSc assemblies. This work provides key insight into the “quasi-species” concept applied to prions, which would not necessarily rely on prion sub-strains as constituent but on structural PrPSc heterogeneity within prion population.

Production and STEM examination of controlled-size silver clusters

1983 ◽  
Vol 41 ◽  
pp. 338-339
Author(s):  
M. A. Listvan ◽  
R. P. Andres
Keyword(s):  
Cluster Size ◽  
Metal Clusters ◽  
Experimental Parameter ◽  
Carbon Films ◽  
Metal Species ◽  
Silver Clusters ◽  
Free Jet ◽  
Size Dependent ◽  
Cluster Properties ◽  
Controllable Size

Knowledge of the function and structure of small metal clusters is one goal of research in catalysis. One important experimental parameter is cluster size. Ideally, one would like to produce metal clusters of regulated size in order to characterize size-dependent cluster properties.A source has been developed which is capable of producing microscopic metal clusters of controllable size (in the range 5-500 atoms) This source, the Multiple Expansion Cluster Source, with a Free Jet Deceleration Filter (MECS/FJDF) operates as follows. The bulk metal is heated in an oven to give controlled concentrations of monomer and dimer which were expanded sonically. These metal species were quenched and condensed in He and filtered to produce areosol particles of a controlled size as verified by mass spectrometer measurements. The clusters were caught on pre-mounted, clean carbon films. The grids were then transferred in air for microscopic examination. MECS/FJDF was used to produce two different sizes of silver clusters for this study: nominally Ag6 and Ag50.

Transfer Technique for Electron Microscopy of Membrance Filter Samples

1974 ◽  
Vol 32 ◽  
pp. 554-555
Author(s):  
Lawrence W. Ortiz ◽  
Bonnie L. Isom
Keyword(s):  
Electron Microscopy ◽  
Electron Microscope ◽  
Pore Size ◽  
Membrane Filters ◽  
Size Dependent

A procedure is described for the quantitative transfer of fibers and particulates collected on membrane filters to electron microscope (EM) grids. Various Millipore MF filters (Millipore AA, HA, GS, and VM; 0.8, 0.45, 0.22 and 0.05 μm mean pore size) have been used with success. Observed particle losses have not been size dependent and have not exceeded 10%. With fibers (glass or asbestos) as the collected media this observed loss is approximately 3%.

Spindle scaling mechanisms

2020 ◽  
Vol 64 (2) ◽  
pp. 383-396
Author(s):  
Lara K. Krüger ◽  
Phong T. Tran
Keyword(s):  
Cell Size ◽  
Spindle Assembly ◽  
Dependent Manner ◽  
Post Translational Modification ◽  
Size Dependent ◽  
A Cell ◽  
Chromosome Separation ◽  
Spindle Elongation ◽  
Protein Gradients ◽  
Spindle Structure

Abstract The mitotic spindle robustly scales with cell size in a plethora of different organisms. During development and throughout evolution, the spindle adjusts to cell size in metazoans and yeast in order to ensure faithful chromosome separation. Spindle adjustment to cell size occurs by the scaling of spindle length, spindle shape and the velocity of spindle assembly and elongation. Different mechanisms, depending on spindle structure and organism, account for these scaling relationships. The limited availability of critical spindle components, protein gradients, sequestration of spindle components, or post-translational modification and differential expression levels have been implicated in the regulation of spindle length and the spindle assembly/elongation velocity in a cell size-dependent manner. In this review, we will discuss the phenomenon and mechanisms of spindle length, spindle shape and spindle elongation velocity scaling with cell size.

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