A macroscopic model of traffic jams in axons

The purpose of this paper is to develop a minimal macroscopic model capable of explaining the formation of traffic jams in fast axonal transport. The model accounts for the decrease of the number density of positively (and negatively) oriented microtubules near the location of the traffic jam due to formation of microtubule swirls; the model also accounts for the reduction of the effective velocity of organelle transport in the traffic jam region due to organelles falling off microtubule tracks more often in the swirl region. The model is based on molecular-motor-assisted transport equations and the hydrodynamic model of traffic jams in highway traffic. Parametric analyses of the model’s predictions for various values of viscosity of the traffic flow, variance of the velocity distribution, diffusivity of microtubule-bound and free organelles, rate constants for binding to and detachment from microtubules, relaxation time, and average motor velocities of the retrograde and anterograde transport, are carried out.     

Nucleotide binding of the C-terminal domains of the major histocompatibility complex-encoded transporter expressed in Drosophila melanogaster cells

The C-terminal domains of the mouse transporter associated with antigen processing (TAP) were expressed as soluble proteins in Drosophila melanogaster cells and labeled by [-³²P]8-azido-ATP after UV-irradiation. The relative potencies of the nucleotides in preventing azido-ATP labeling were in the order of ATP> GTP> CTP> ITP> UTP for both the TAP1 and TAP2 C-terminal domains, suggesting ATP to be the natural substrate of the transporter. Our data provide the first evidence that the individual C-terminal domain of either TAP1 or TAP2 can be expressed as a functional ATP-binding protein.     

Energy release and countermeasures for sand casting explosion accidents

Abstract

Sand casting explosion accidents seriously threaten employees' lives and the harmony and stability of society, such as casualties, equipment trouble and environmental pollution. The main purpose of this study was to determine the water requirement for sand casting explosion accidents, and then corresponding safety measures were proposed to prevent such accidents. First, the relationship between the water condition and temperature for such accidents was achieved based on an energy release equation in compressed gas expansion and the ideal gas state equation. The volume of vapor expanded rapidly as the temperature rises, which was also the immediate cause of sand casting expansion accidents. Also, the water requirement for the sand casting expansion accidents decreased rapidly as the temperature rises. Then, a bow-tie model was adopted for preventing the causes and consequences of sand casting explosion accidents. Three main causes were identified, namely molten metal meeting ponding, failure of cavity exhaust and low strength sand of sand mold, and 11 prevention safety measures were adopted to prevent the causes of such accidents. In addition, three consequences were identified, namely casualties, equipment trouble and environment pollution, and ten mitigation safety measures were adopted to mitigate the consequences of such accidents.     

Distribution of Saprophytic Bacteria in the Atomic Submarine Accident Zone in Chazhma Bay, Sea of Japan

The numerical and taxonomic composition of saprophytic bacteria was studied in the atomic submarine accident zone in Chazhma Bay. With increasing depth in the epicenter of the accident zone, the mean of the ratio of bacterial taxa in the resistance series tends toward a constant. The numerical structure of the pelagic saprophytic bacterial assemblage becomes ordered as the bottom is approached. Analysis of radioactive suspended matter allowed us to obtain model distribution of numbers of all saprophytes and each taxon from the different environmental sources (sediment surface and upper layers of the sea).Original Russian Text Copyright © 2005 by Biologiya Morya, Ivanova, Gorshkova, Mikhailov, Sergeev, Gladkikh, Goryachev, Dudarev, Botsul, Mozherovsky, Slinko, Kiselev.