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centrifuge and rcf

Wei Jiang, Rui Hua, Mengping Wei, Chenhong Li, Zilong Qiu, Xiaofei Yang, Chen Zhang
Lentiviral technology has proven to be a powerful tool to express exogenous genes in dividing and non-dividing cells. Currently, most protocols for generating high-titer lentivirus require ultracentrifugation, which can be an instrumental barrier for routine operations in a laboratory. In this study, the effect of relative centrifugal force (RCF) on the concentration efficiency of the lentivirus was systematically explored, and it was found that sucrose gradient centrifugation with a relatively low speed (≤10,000 g) robustly produces a high-titer virus (up to 2×10(8) TU/ml)...
2015: Scientific Reports
Qian Li, Chen-Guang Liu, Yu Yu
Four batches of oleoyl alginate ester (OAE) nanoparticles with narrow size distribution were rapidly separated from the initial batch of nanoparticles by means of centrifugation at the relative centrifugal force (RCF) between 270×g and 6750×g after adjusting the zeta potential. The size of nanoparticles decreased with increasing speed of centrifugation, and the polydispersity of nanoparticles significantly decreased. As particle size increased the loading capacity also increased, while transport across Caco-2 cells and the cellular uptake of nanoparticles in jejunum decreased...
June 25, 2015: Carbohydrate Polymers
M Delahaye, K Lawrence, S J Ward, M Hoare
An ultra scale-down method is described to determine the response of cells to recovery by dead-end (batch) centrifugation under commercially defined manufacturing conditions. The key variables studied are the cell suspension hold time prior to centrifugation, the relative centrifugal force (RCF), time of centrifugation, cell pellet resuspension velocities, and number of resuspension passes. The cell critical quality attributes studied are the cell membrane integrity and the presence of selected surface markers...
May 2015: Biotechnology and Bioengineering
Amal S Abu Almakarem, Katie L Heilman, Heather L Conger, Yury M Shtarkman, Scott O Rogers
BACKGROUND: When samples are collected in the field and transported to the lab, degradation of the nucleic acids contained in the samples is frequently observed. Immediate extraction and precipitation of the nucleic acids reduces degradation to a minimum, thus preserving accurate sequence information. An extraction method to obtain high quality DNA in field studies is described. FINDINGS: DNA extracted immediately after sampling was compared to DNA extracted after allowing the sampled tissues to air dry at 21°C for 48 or 72 hours...
2012: BMC Research Notes
M Merolla, M A Nardi, J S Berger
BACKGROUND: Light transmission aggregometry (LTA) is considered the gold standard for investigating platelet activity ex vivo. However, LTA protocols are not standardized, and differences in LTA procedure are a potential source of variance in results. Centrifugation speed is an essential component of platelet preparation in LTA, has yet to be standardized, and may affect platelet aggregation results. We sought to investigate the effect of relative centrifugal force (RCF) intensity on LTA results...
February 2012: International Journal of Laboratory Hematology
Zhanwen Xing, Jinrui Wang, Hengte Ke, Bo Zhao, Xiuli Yue, Zhifei Dai, Jibin Liu
Novel biocompatible nanobubbles were fabricated by ultrasonication of a mixture of Span 60 and polyoxyethylene 40 stearate (PEG40S) followed by differential centrifugation to isolate the relevant subpopulation from the parent suspensions. Particle sizing analysis and optical microscopy inspection indicated that the freshly generated micro/nanobubble suspension was polydisperse and the size distribution was bimodal with large amounts of nanobubbles. To develop a nano-sized contrast agent that is small enough to leak through tumor pores, a fractionation to extract smaller bubbles by variation in the time of centrifugation at 20g (relative centrifuge field, RCF) was suggested...
April 9, 2010: Nanotechnology
(no author information available yet)
This appendix provides r(max) values (the maximum value of the rotating radius between the particle being centrifuged and the axis of rotation) for commonly used rotors manufactured by Du Pont (Sorvall), Beckman, Fisher, and IEC. Additionally, nomograms are provided for determining the relative centrifugal force (RCF) where speed and r(max) are known, or the speed where RCF and r(max) are known.
May 2001: Current Protocols in Protein Science
(no author information available yet)
This appendix provides rmax (the distance between the axis of rotation and the bottom of the centrifuge tube as it sits in the well or bucket of the rotor) values for commonly used rotors manufactured by Du Pont (Sorvall), Beckman, Fisher, and IEC. Nomograms are also given to determine the relative centrifugal force (RCF) where speed and rmax are known, or the speed where RCF and rmax are known.
May 2001: Current Protocols in Human Genetics
Tae-Wan Kim, Jung-Won Keum, In-Seok Oh, Cha-Yong Choi, Chang-Gil Park, Dong-Myung Kim
In this study, as a part of our efforts to improve the robustness and economical feasibility of cell-free protein synthesis, we developed a simple method of preparing the cell extracts used for catalyzing cell-free protein synthesis reactions. We found that the high-speed centrifugation, pre-incubation, and dialysis steps of the conventional procedures could be omitted without losing the translational activity of the resulting cell extract. Instead, a simple centrifugation step at low speed (12,000 RCF for 10 min) followed by a brief period of incubation was sufficient for the preparation of an active extract to support cell-free protein synthesis with higher productivity and consistency...
December 1, 2006: Journal of Biotechnology
Catherine D Reyes, Andrés J García
A quantitative analysis of cell adhesion is essential in understanding physiological phenomena and designing biomaterials, implant surfaces, and tissue-engineering scaffolds. The most common cell adhesion assays used to evaluate biomaterial surfaces lack sensitivity and reproducibility and/or require specialized equipment and skill-intensive operation. We describe a modified centrifugation cell adhesion assay that uses simple and convenient techniques with standard laboratory equipment and provides reliable, quantitative measurements of cell adhesion...
October 1, 2003: Journal of Biomedical Materials Research. Part A
John M Graham
The formation of self-generated gradients of iodixanol from a solution of uniform concentration requires the use of vertical or near-vertical rotors. The density profile that is generated depends upon the sedimentation path length of the rotor, centrifugation time, RCF and temperature. Modulation of the starting concentration changes the density range of the gradient. This Protocol Article illustrates the effect of these parameters on gradient shape in a few selected rotors. Because the gradients are formed by the centrifugal field, they are highly reproducible and easy to execute...
May 16, 2002: TheScientificWorldJournal
J Perera, D M Arachchi
Direct microscopy is the only available method for diagnosis of tuberculosis in most centres in developing countries. Methods to improve the sensitivity of direct smear are an urgent requirement. Sputum specimens artificially seeded with known concentrations of Mycobacterium tuberculosis were liquefied and decontaminated with sodium hydroxide-sodium citrate-N-actyl-L-cysteine solutions. They were subjected to different centrifugation forces and centrifugation times after which the centrifuged deposits were examined by smear and culture...
July 1999: Transactions of the Royal Society of Tropical Medicine and Hygiene
H C Margolis, Y P Zhang, J van Houte, E C Moreno
Pooled plaque samples were obtained from (1) coronal surfaces of two groups of caries-free (CF) subjects, (2) coronal 'white-spot' surface areas of a group of caries-positive (CP) subjects, and (3) exposed, sound root surfaces of root caries-free (RCF) and root caries-positive (RCP) subjects. The plaque samples were obtained before and 3 min after a 1 min rinse with a 0.5, 1, 2, 5 and 10% sucrose solution. Plaque fluid was then isolated from each plaque sample by centrifugation and analyzed for inorganic ions, organic acids, and pH values...
1993: Caries Research
E M Magnus
In response to specific treatment of vitamin B12 deficient, anaemic patients there is an influx of folate into the young, circulating red cells. To separate new and old cells, capillary tubes filled with whole blood were centrifuged and the packed red cell column divided into top (T), middle (M) and bottom (B) layer. The newest cells are found in the T layer. The increase in red cell folate (RCF) concentration starts before, during or after the reticulocyte response, and is therefore not directly related to folate metabolism in the red precursor cells in the marrow...
March 1980: Scandinavian Journal of Haematology
V D Paponov, O B Fabrichnaia, I A Kuznetsov
Rheological properties of the water solutions of H+- and Na+-DNA were studied at shear rates in the range of 0.12-126 sec-1. It was found that the concentration dependences of reduced viscosity of these systems have the maxima which displaced to the left along abscissa after ultrasonic degradation or long keeping and to the right after the salt or urea addition. Na+-DNA solutions have the rheological curve of flow typical of pseudoplastical systems (RCF-1): the viscosity decreases with increasing shear rate...
November 1984: Molekuliarnaia Biologiia
P J Mountford
Platelet contamination of 111In-leucocytes can be minimized by centrifugation of leucocyte-rich plasma before labelling. The differential recovery of leucocytes and platelets from centrifugation depends on various biological and physical factors. Experimental measurements have been made of the effect of some of these factors. The ratio of leucocyte-to-platelet recovery was increased by using more than one centrifugation, and by using a low relative centrifugal force (RCF). To extend the study, a method of calculating cell recovery from centrifugation was developed, based on the experimental results...
February 1986: Nuclear Medicine Communications
S Ratnam, S B March
Optimum relative centrifugal force (RCF) and centrifugation time to concentrate mycobacteria in clinical specimens were determined by processing split samples of sputa and urines containing mycobacteria with combinations of different RCFs and centrifugation times. Although individual test results showed considerable variation in the recovery rates of mycobacteria in the sediment, the data indicated that higher recovery rates occurred as centrifugation speed and time were increased. With a 15- to 20-min centrifugation time, on the average, 67 to 71% of mycobacteria were recovered at an RCF of 2,074 X g, and 76 to 80% were recovered at 3,005 or 3,895 X g at maximum radius...
March 1986: Journal of Clinical Microbiology
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