Results 1 - 10 of 10236
Results 1 - 10 of 10236. Search took: 0.123 seconds
|Sort by: date | relevance|
[en] Particle track membranes (PTM) are ideal surface filters. Their parameters can be adjusted to the separation problem. In an investigation several RoTrac PTM with different pore parameters were tested in dead end filtration of microorganism suspensions. The used species were rod-like ''E. coli, Serratia marcescens, Pseudomonas diminuta'' with a rigid cell wall. The suitability of PTM in bacteria removal as well as in bacteria free filtration was proven. Blocking was very strong for membranes with pore diameters in size range of the microorganisms. Through the filtrate had immense reduced bacteria counts in these cases, it was generally not sterile. For the rigid bacteria type membranes with 0.2 μm and smaller pore diameters always assure a bacteria free filtrate even for a very high bacteria count of about 107 to 108 bacteria/ml. Flux (and thus the filterable volume) corresponds to values of competitive membranes. The filtration mechanism is governed by several processes. Both the membrane (pore diameter, shape, inclination, porosity) and the microorganisms (size, shape, count) have influence. (author). 13 refs, 7 figs, 1 tab
[en] Hydrophobicity is known to play a key role in the biological distribution of materials but is often an overlooked parameter when conjugating targeting agents, drugs, and dyes to dendrimers. This review examines the impact of hydrophobic variation in stochastically conjugated dendrimers as well as materials where synthetic methods or approaches to purification provide more controlled samples. Hydrophobic interactions are considered for three general classes: (1) terminal functional group modifications, (2) bioactive small molecules chosen to interact with receptors and proteins as targeting agents and/or drugs, and (3) imaging agents to track biological activity. Impacts on membrane interaction and cellular uptake, biodistribution, interaction with transport proteins, and pharmacokinetics are discussed. The size range of the dendrimers discussed is ~ 1–10 nm.
[en] Experimental results have been presented of selectivity for glucose and ascorbic acid of nuclear filters prepared from polyethylene terephthalate after appropriate physical and chemical modification. For selected and prepared for investigation nuclear filters: hydrodynamic pore diameter, electro-kinetic potential and density of surface pores charge have been preliminary determined. It can be stated on the base of results obtained that the general possibility exists to apply nuclear filters as selective elements of bio-sensors. 7 refs, 2 tabs
[en] The possibility of particle track membranes use in hospital treatment of burns have been discussed. The introductory research with patients having different types of skin imitation has been conducted. All tests with PTM dressing have given positive results. 4 tabs
[en] Spatial stochastic molecular simulations in biology are limited by the intense computation required to track molecules in space either in a discrete time or discrete space framework, which has led to the development of parallel methods that can take advantage of the power of modern supercomputers in recent years. We systematically test suggested components of stochastic reaction-diffusion operator splitting in the literature and discuss their effects on accuracy. We introduce an operator splitting implementation for irregular meshes that enhances accuracy with minimal performance cost. We test a range of models in small-scale MPI simulations from simple diffusion models to realistic biological models and find that multi-dimensional geometry partitioning is an important consideration for optimum performance. We demonstrate performance gains of 1-3 orders of magnitude in the parallel implementation, with peak performance strongly dependent on model specification.
[en] Most existing flocking algorithms assume one single virtual leader and rely on information on both relative positions and relative velocities among neighboring agents. In this paper, the problem of controlling a flock of mobile autonomous agents to follow multiple virtual leaders is investigated by using only position information in the sense that agents with the same virtual leader asymptotically attain the same velocity and track the corresponding virtual leader based on only position measurements. A flocking algorithm is proposed under which every agent asymptotically attains its desired velocity, collision between agents can be avoided, and the final tight formation minimizes all agents' global potentials. A simulation example is presented to verify and illustrate the theoretical results. (general)