A Confocal Microscopic Study of Gene Transfer into the Mesencephalic Tegmentum of Juvenile Chum Salmon,Oncorhynchus keta,Using Mouse Adeno-Associated Viral Vectors

To date, data on the presence of adenoviral receptors in fish are very limited. In the present work, we used mouse recombinant adeno-associated viral vectors (rAAV) with a calcium indicator of the latest generation GCaMP6m that are usually applied for the dorsal hippocampus of mice but were not previously used for gene delivery into fish brain. The aim of our work was to study the feasibility of transduction of rAAV in the mouse hippocampus into brain cells of juvenile chum salmon and subsequent determination of the phenotype of rAAV-labeled cells by confocal laser scanning microscopy (CLSM). Delivery of the gene in vivo was carried out by intracranial injection of a GCaMP6m-GFP-containing vector directly into the mesencephalic tegmentum region of juvenile (one-year-old) chum salmon, Oncorhynchus keta. AAV incorporation into brain cells of the juvenile chum salmon was assessed at 1 week after a single injection of the vector. AAV expression in various areas of the thalamus, pretectum, posterior-tuberal region, postcommissural region, medial and lateral regions of the tegmentum, and mesencephalic reticular formation of juvenile O. keta was evaluated using CLSM followed by immunohistochemical analysis of the localization of the neuron-specific calcium binding protein HuCD in combination with nuclear staining with DAPI. The results of the analysis showed partial colocalization of cells expressing GCaMP6m-GFP with red fluorescent HuCD protein. Thus, cells of the thalamus, posterior tuberal region, mesencephalic tegmentum, cells of the accessory visual system, mesencephalic reticular formation, hypothalamus, and postcommissural region of the mesencephalon of juvenile chum salmon expressing GCaMP6m-GFP were attributed to the neuron-specific line of chum salmon brain cells, which indicates the ability of hippocampal mammal rAAV to integrate into neurons of the central nervous system of fish with subsequent expression of viral proteins, which obviously indicates the neuronal expression of a mammalian adenoviral receptor homolog by juvenile chum salmon neurons.     

Cascade subcritical liquid-salt reactor for burning transplutonium actinides

A cascade subcritical liquid-salt reactor designed for burning long-lived components of the radioactive wastes of the nuclear fuel cycle is examined. The cascade scheme of the reactor makes it possible to decrease by a factor of three the power of the driving accelerator as compared with conventional accelerator-blanket systems of equal power. The fuel composition of the reactor consists of 20% Np, Am, Cm, and other transplutonium elements and 80% plutonium, which are dissolved in a salt melt NaF(50%)-ZrF₄(50%). For a 10 MW proton accelerator, 1 GeV proton energy (10 mA current) and subcriticality depth 0.05, the thermal power of the reactor is 800 MW, which permits burning ∼70 kg/yr Np, Am, Cm, and other transplutonium actinides, i.e., service five VVéR type reactors of equal power. __________ Translated from Atomnaya énergiya, Vol. 101, No. 2, pp. 116–125, August, 2006.     

Microstructure Control of In-Situ-Toughened α-SiAlON Ceramics

Single-phase α-SiAlON with elongated grains is obtained from α-Si₃N₄ powder for a broad range of compositions of practical interest. Following the concept of nucleation and growth, two-step firing is used for microstructure control. This method takes advantage of the slow transformation reaction from α-Si₃N₄ to α-SiAlON at low temperature when the composition is near the α-SiAlON phase boundary and, hence, is marginally stable. For more-stable compositions, the seeding of α-SiAlON crystals is more effective, because it allows elongated grains to grow onto the seed crystals. The fracture toughness is strongly correlated with the microstructure and is enhanced greatly in the optimized materials.     

Variational Determination of the Crack Trajectory in Inhomogeneous Media

Propagation of a crack through inhomogeneous media is considered in the variational formulation, whereby the path corresponding to the extremum of energy release during fracture is sought. A non-linear differential equation is obtained for the crack trajectory in an inhomogeneous medium subjected to specified tensile loading. A linearized form of this equation is investigated in order to characterise the crack propagation in media with different effective characteristics.     

Maintenance contract assessment for aging systems

This paper considers an aging system, where the system failure rate is known to be an increasing function. After any failure, maintenance is performed by an external repair team. Repair rate and cost of repair are determined by a corresponding maintenance contract with a repair team. There are many different maintenance contracts suggested by the service market to the system owner. In order to choose the best maintenance contract, a total expected cost during a specified time horizon should be evaluated for an aging system. In this paper, a method is suggested based on a piecewise constant approximation for the increasing failure rate function. Two different approximations are used. For both types of approximations, the general approach for building the Markov reward model is suggested in order to assess lower and upper bounds of the total expected cost. Failure and repair rates define the transition matrix of the corresponding Markov process. Operation cost, repair cost and penalty cost for system failures are taken into account by the corresponding reward matrix definition. A numerical example is presented in order to illustrate the approach. Copyright © 2008 John Wiley & Sons, Ltd.     

Hierarchy of maturation parameters in oil-source rock correlations. Case study: Drmno depression, Southeastern Pannonian Basin, Serbia and Montenegro

Hierarchy of triterpane, sterane, naphthalene and phenanthrene maturation parameters in oil-source rock correlations (Drmno depression, southeastern part of the Pannonian Basin, Serbia and Montenegro) was evaluated. Different triterpane and sterane parameters were found to be very similar in all investigated samples. Phenanthrene and naphthalene maturation parameters demonstrated much less uniformity, and thus higher applicability. In order to establish a detailed hierarchy of these maturation parameters, the factor analysis was used. Parameters based on isomerization reactions (α → β) of methylnaphthalenes and methylphenanthrenes, having high loadings, defined the statistically most significant factor 1. Parameters based on dealkylation processes of dimethyl- and trimethylphenanthrenes into methylphenanthrenes, having extremely high loadings values, determined factor 2. In the last significant, factor 3, high loadings were observed with triterpane and sterane parameters. The factor analysis involving just the phenanthrene and naphthalene isomerization parameters, classified methylphenanthrene isomerization parameters into factor 1. Among the naphthalene isomerization maturation parameters a certain hierarchy was also observed, which depended on whether the parameters represented isomer ratios which differed on the position of one or two alkyl groups. General conclusion based on factor analysis is in agreement with theoretical presumptions concerning the transformations of phenanthrene and naphthalene isomers.     

Rotational isomeric relaxation in poly(ethylene glycols) studied by acoustic spectroscopy

Acoustic spectra have been investigated for a series of poly(ethylene glycols) (PEGs) with molecular masses of 200, 400, and 600. Velocity of sound propagation c and sound attenuation αf^?2 were measured in the frequency interval from 5 to 2500 MHz and temperature interval from 278 to 343 K. The acoustic spectra of PEGs in the frequency range studied comprise two simple dispersion regions. Characteristic parameters for these regions were calculated. Possible molecular mechanisms of the processes responsible for the regions are considered. It turns out that the low-frequency dispersion region is caused by conformational restructuring processes in PEG molecules. The main contribution to the sound attenuation was shown to be caused by rotational isomeric relaxation process of the type trans-trans?trans-gause. Thermodynamical and kinetic parameters of the low-frequency relaxation region are reported.     

A Comparative Characterization of Kaolins of Provenance from the Prosyanovskoe and Kyshtymskoe Deposits Subjected to Mechanochemical Activation in an Aqueous Medium

The effect of mechanical activation in an aqueous medium on properties of kaolins of provenance from the Prosyanovskoe and Kyshtymskoe deposits — typical representatives of high-grade and low-grade kaolins — is studied. The activation in an aqueous medium produces a substantial effect on the crystallinity of kaolins and the process of phase formation in heat-treated kaolins. The mechanochemical activation, backed up by an accumulated and systematized experimental data, can provide a simple and readily available way toward improving the quality of kaolins.