Optimization of Pathogen Capture in Flowing Fluids with Magnetic Nanoparticles

Magnetic nanoparticles have been employed to capture pathogens for many biological applications; however, optimal particle sizes have been determined empirically in specific capturing protocols. Here, a theoretical model that simulates capture of bacteria is described and used to calculate bacterial collision frequencies and magnetophoretic properties for a range of particle sizes. The model predicts that particles with a diameter of 460 nm should produce optimal separation of bacteria in buffer flowing at 1 L h⁻¹. Validating the predictive power of the model, Staphylococcus aureus is separated from buffer and blood flowing through magnetic capture devices using six different sizes of magnetic particles. Experimental magnetic separation in buffer conditions confirms that particles with a diameter closest to the predicted optimal particle size provide the most effective capture. Modeling the capturing process in plasma and blood by introducing empirical constants (c_e), which integrate the interfering effects of biological components on the binding kinetics of magnetic beads to bacteria, smaller beads with 50 nm diameters are predicted that exhibit maximum magnetic separation of bacteria from blood and experimentally validated this trend. The predictive power of the model suggests its utility for the future design of magnetic separation for diagnostic and therapeutic applications.     

A new mumps virus lineage found in the 1995 mumps outbreak in western Switzerland identified by nucleotide sequence analysis of the SH gene

We determined the nucleotide sequence of the SH gene its flanking regions over a range of 380 nucleotides for three distinct mumps virus (MUV) isolates. Two isolates from the 1992 mumps epidemic in Western Switzerland and one MUV isolated in 1995 in the same geographic area have been analyzed and compared to 16 recently published SH nucleotide sequences and their presumed amino acid sequences. The nucleotide sequences from the 1992 MUV isolates were identical and closely related to two MUV strains from Eastern Switzerland and strains from the U.K. The MUV isolated in 1995 is clearly different from all other strains.     

Comparative fate of 1,1-diphenylethylene (DPE), 1,1-dichloro-2,2-bis(4-Chlorophenyl)-ethylene (DDE), and pentachlorophenol (PCP) under alternating aerobic and anaerobic conditions

First, annual cost of electronic filing of medical images were calculated and compared with that of film storage in two hospitals under different conditions. Storage of medical images using a pixel size of 100 microns x 100 microns and 2-byte depth on the 130 mm, 650 MB magneto-optical disks costs with four times as much as the cost for film storage. However, 175 microns x 175 microns 12 bits combined with implementation of lossless compression would reduce the cost to a level equal to that for films storage. Doubled or tripled densities of MOD will improve the cost ever further. Second, the effectiveness of Hospital Information System/Radiological Information System (HIS/RIS) was evaluated. Examination time, film delivery time and the total turn-around time was markedly shortened by more than 23 hours on average. Our measurement method employing IC cards in pre-post HIS/RIS/PACS procedures is generally applicable to other hospitals. Third, to determine the optimal method of maximizing the efficacy of diagnostic imaging, 260 questionnaires were sent to the staff of 13 university hospitals. Every situation was described by both a radiologist and the physician who ordered the examination and received the reports and images. The level of technical efficacy and diagnostic accuracy of radiology strongly influenced the diagnostic thought processes of the physician.     

Kinetic Monte-Carlo simulation of network formation

Summary the simulation described in Part I was applied to random step polyaddition of a trifunctional monomer and the results were compared with exact solution for an infinite system. The gel point conversions, the weight-average degree of polymerization before (P _w) and beyond (P _w,sol) the gel point, the sol fraction and the cycle rank were used for comparison. The best way for detection of the gel point conversion is the extrapolation of the gel fraction, w _g, to w _g=0. The largest fluctuations are exhibited by P _w and P _w,sol. To get results closer to the exact ones, one can repeat several experiments with smaller number of units or increase the number of units, the former way being somewhat more economical. Typical orders of magnitude used were 10⁷ monomeric units.     

Depression in college students: Personality and experiential factors.

In this study we examined the nature of college-student depression and its relation to personality variables and to experiences unique to college life. Thirty-five depressed and 39 nondepressed students completed a depression inventory, a series of personality scales, and a survey developed to investigate the impact of potentially distressing components of college life. Results revealed that college-student depression, though mild in intensity, represents a serious problem: Three quarters of depressed students had been depressed for more than 3 months, and half had contemplated suicide. Both personality characteristics and experiential variables were found to be significantly related to depression, together accounting for approximately half the variance. We examined individual personality traits and experiential variables that were found to differ between depressed and nondepressed subjects, and we discuss the implications of the findings for counseling and for future research. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Low strain rate plasticity of continuously cast carbon steels

By a special plastometric method, the straightening operation of a vertically cast strand of two carbon steels was simulated. The temperature dependence of the low strain rate plasticity of both the steels examined is analogous although caused by very different reasons. As to the plain carbon steel, the amount of ferrite and its location is of prime importance, whereas in the case of eutectoid steel various modes of fracture and the influence of temperature on the relative plasticity of type II MnS inclusions are influencial. To avoid transverse cracking, it seems to be suitable to keep the strand at a rather high temperature (above 900 °C). Temperature cycling seems to be fundamental as to the structural changes taking place in the strand (grain size refining, ferrite fraction if any), whereas analogous influences of straining are more or less inexpressive. Of course, the results obtained are of quality only since the practical and laboratory conditions differ significantly. The knowledge obtained could be applied in regulating the intensity of strand cooling with the aim of lowering the waste portion and improving the surface quality of worked products.