Oxygen as a morphogenic factor in sponges: expression of a tyrosinase gene in the sponge Suberites domuncula

Sponges live in a symbiotic relationship with microorganisms, especially bacteria. Here we show, using the demosponge Suberites domuncula as a model, that the sponge expresses the enzyme tyrosinase which synthesizes diphenols from monophenolic compounds. It is assumed that these products serve as carbon source for symbiotic bacteria to grow.     

散砂及表层海洋(砂质)沉积物中的声速

根据作者的颗粒介质中的声传播理论,应用熄灭定理,给出了颗粒介质中的声速公式。对表层海洋(砂质)沉积物及气砂中的声速作了数值计算,结果表明,在大气压力下,气砂中的声速比空气中的声速小。而在表层海洋沉积物中,散射相互作用的影响不可忽视,粘滞波相互作用对声速的影响不大。刚性粒子理论结果与发表的实验数据比较符合,弹性粒子理论模型应该说是符合实际的,但给出的结果反而比实验数据小,这表明更多的实验测量是需要的。还比对分析了已发表的实验数据,结果表明,颗粒介质理论是更适宜于研究气砂中的声传播问题。     

Forward scatter target strength extraction in a marine environment (L)

A 48 m rail with a moving receiver was used to measure forward scattering from a spherical shell lying on the bottom in the Gulf of Mexico. The target was mid-way between the source and rail, on a line from the source bisecting the rail. The major obstacle to the measurement of forward scattering is the much stronger source signal which overlaps the scattered signal in space and time. Here, forward scattered target strength is obtained by processing the received signals using a wavenumber filter to remove the incident wave. The result compares favorably to that obtained from numerical predictions.     

Thermodynamic treatment of nonphysical systems: Formalism and an example (Single-lane traffic)

An effort is made to introduce thermodynamic and statistical thermodynamic methods into the treatment of nonphysical (e.g., social, economic, etc.) systems. Emphasis is placed on the use of theentire thermodynamic framework, not merely entropy. Entropy arises naturally, related in a simple manner to other measurables, but does not occupy a primary position in the theory. However, the maximum entropy formalism is a convenient procedure for deriving the thermodynamic analog framework in which undetermined multipliers are thermodynamic-like variables which summarize the collective behavior of the system. We discuss the analysis of Levine and his coworkers showing that the maximum entropy formalism is the unique algorithm for achieving consistent inference of probabilities. The thermodynamic-like formalism for treating a single lane of vehicular traffic is developed and applied to traffic in which the interaction between cars is chosen to be a particular form of the follow-the-leader type. The equation of state of the traffic, the distributions of velocity and headway, and the various thermodynamic-like parameters, e.g., temperature (collective sensitivity), pressure, etc. are determined for an experimental example (Holland Tunnel). Nearest-neighbor and pair correlation functions for the vehicles are also determined. Many interesting and suggestive results are obtained,     

A selfconsistent thermodynamic model of a metal solid (Using aluminum as an example)

The fundamental principles of a selfconsistent thermodynamic approach to a simultaneous calculation of the entire set of basic thermodynamic functions of an elementary nonmagnetic metal, taking into account the thermal phonon anharmonicity and the concomitant Debye temperature θ dependence, are reported. It is shown that given a step-by-step analysis, the Debye temperature includes not only lattice but also electronic parameters, which could be interpreted as an indirect thermodynamic evidence of electron-phonon interaction in metals. The model adequacy, both in terms of its quantitative and qualitative validity, is shown by the example of aluminum. __________ Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 12, pp. 19–27, December, 2005.     

Quantum cryptography using photon “frequency” states (example of a possible realization)

A quantum cryptosystem is proposed using single-photon states with different frequency spectra as information carriers. A possible experimental implementation of the cryptosystem is discussed. Zh. éksp. Teor. Fiz. 114, 526–537 (August 1998)     

Possible mechanism of oil formation in a flow of supercritical fluid (using carbon dioxide as an example)

An experimental study of the supercritical fluid extraction of the organic substance with carbon dioxide from rock and soil showed that a supercritical (SC) fluid can dissolve, transfer, and accumulate petroleum-like hydrocarbons including relict ones. It was hypothesized that during the supercritical extraction, the dissolution of organic substances is accompanied by their mechanochemical transformation in the micropores and microcracks of the solid. The resulting changes in the composition, structure, and distribution of the individual hydrocarbons are similar to those in petroleum-mother rocks. We can therefore assume that fast mechanochemical transformation of the dispersed organic matter of sedimentary rocks takes place in a flow of a deep supercritical fluid. This, in turn, would allow one to revise the time scale of oil accumulation from millions to possibly hundreds of years.     

Click-evoked potentials in a large marine mammal, the adult male northern elephant seal (Mirounga angustirostris)

Auditory evoked potential (AEP) hearing studies in marine mammals should consider an expected size-dependent reduction in AEP amplitude. This study is the first to measure the click-evoked response in a large marine mammal, the adult male elephant seal (Mirounga angustirostris). Click stimuli were presented at peak-peak equivalent sound pressure levels of 117-118 dB re: 20 microPa. Three positive peaks (P1-P3) and two negative peaks (N4 and N5) were observed in the AEP. Response latencies were longer than previously observed in a 1.8 yr old seal and the maximum peak-peak amplitude was comparatively reduced by more than 60%. The inverse relationship between size and AEP amplitude will likely require increased averaging with larger subjects and possibly modifications to electrode placement and design in order to increase the quality of recorded evoked responses.     

Novel utilization of waste marine sponge (Demospongiae) as a catalyst in ultrasound-assisted transesterification of waste cooking oil

This study demonstrates the potential of Na-silica waste sponge as a source of low cost catalyst in the transesterification of waste cooking oil aided by ultrasound. In this work an environmentally friendly and efficient transesterification process using Na-loaded SiO₂ from waste sponge skeletons as a solid catalyst is presented. The results showed that the methyl esters content of 98.4 ± 0.4 wt.% was obtainable in less than an hour (h) of reaction time at 55 °C. Optimization of reaction parameters revealed that MeOH:oil, 9:1; catalyst, 3 wt.% and reaction duration of 30 min as optimum reaction conditions. The catalyst is able to tolerant free fatty acid and moisture content up to 6% and 8%, respectively. In addition, the catalyst can be reused for seven cycles while maintaining the methyl esters content at 86.3%. Ultrasound undoubtedly assisted in achieving this remarkable result in less than 1 h reaction time. For the kinetics study at 50–60 °C, a pseudo first order model was proposed, and the activation energy of the reaction is determined as 33.45 kJ/mol using Arrhenius equation.     

Influence of MgO substrate treatment on the structure-sensitive properties of epitaxial films (by the example of iron films)

A new technology of growing thin single-crystal MgO films on the MgO crystal surface using the method of chemical transport reactions is developed. The quality of deposited sublayers is checked with the structure-sensitive properties of iron epitaxial films.     

Multiplet classification of the reducible elementary representations of real semisimple Lie groups: the SO e (p,q) example

A multiplet classification of the reducible elementary representations (=generalized principal series representations) is proposed as a useful intermediate step in the important problem of determining the irreducible composition factors of the elementary representations and their multiplicities and, thus, of the distribution characters of all irreducible representations of real semisimple Lie groups. As an example, the results for the elementary representations of SO _e (p, q) induced from its minimal parabolic subgroup are given. Further research is also indicated. Presented at the 1st National Congress of Bulgarian Physicists, Sofia, September 1983.     

Magnetic contribution to the Debye temperature and the lattice heat capacity of ferromagnetic rare-earth metals (using gadolinium as an example)

A thermodynamic approach that describes the spontaneous magnetic contribution to the Debye temperature of a ferromagnetic metal has been developed using the theory of second-order Landau phase transitions. It is shown that the essential cause of the formation of the spontaneous magnetic contribution to the Debye temperature is the magnetostrictive variation of the volume. By using an expression for the spontaneous magnetic contribution to the Debye temperature, the magneto-phonon contribution to the lattice specific heat is found. The resulting generalized expression for the Debye temperature is found to be in good agreement with experimental data concerning the elastic constants of the ferromagnetic phase of gadolinium. The magneto-phonon heat capacity makes an appreciable contribution to the heat-capacity anomaly of gadolinium close to the Curie point. Fiz. Tverd. Tela (St. Petersburg) 41, 1248–1253 (July 1999)     

Divergence of geometrical optics series at the boundary of its applicability: An analytical example in elementary functions (2D Gaussian beam in free space)

An analytical example in elementary functions is presented (2D Gaussian beam diffraction in free space), which demonstrates the divergence of the geometrical optics (GO) series when the conditions for its applicability are violated. This example shows that accounting for higher terms in GO power series leads to divergence and therefore becomes completely useless beyond the boundaries of GO applicability.     

Comparison of the process of deactivation of homogeneous catalysts by the example of copper(II) compounds in the presence of some additives in various solvents

For a model reaction of tetralylhydroperoxide decomposition, kinetic data for evaluating the catalytic activity of Cu(II) complexes in solvents of different natures were obtained. The experiments were performed using chlorobenzene (aprotic solvent), ethanol (capable of forming intermolecular hydrogen bonds), and ethyl acetate (having no movable proton). The passivation of the catalysts in the presence of benzoic acid and N,N'-bis(o-hydroxybenzoyl) hydrazine (inhibitor) in these solvents was studied. It was found that the tested additives produce different effects on the catalytic activity of the initial and reaction-modified forms of Cu(II).     

A comparative study of two marine catfish (Siluriformes,Ariidae): Cytogenetic tools for determining cytotaxonomy and karyotype evolution

The family Ariidae comprises approximately 130 catfish species on both warm-temperate and tropical continental shelves around the world. The systematics of the group is problematic, with several misidentification problems. In order to better understand the evolutionary relationships in the family, the present study used a cytogenetic approach to characterize two populations of Genidens genidens and two populations of Aspistor luniscutis from the southern coast of Brazil using conventional techniques and fluorescent in situ hybridization with 18S rDNA probes. The two species had the same diploid number (2n = 56), high fundamental numbers and similar banding patterns, thereby corroborating the karyotypic homogeneity proposed for the group. Single nucleolus organizer regions (NORs) were found in the genus Genidens and multiple NORs were found in Aspistor, which are considered an important cytotaxonomic marker for this genus. Karyotypic evolution trends were hypothesized, providing a better understanding of the karyotype diversity and chromosome evolution processes.     

Topological Superconductivity in Cu(x)Bi(2)Se(3)

A topological superconductor (TSC) is characterized by the topologically protected gapless surface state that is essentially an Andreev bound state consisting of Majorana fermions. While a TSC has not yet been discovered, the doped topological insulator Cu(x)Bi(2)Se(3), which superconducts below ～3 K, has been predicted to possess a topological superconducting state. We report that the point-contact spectra on the cleaved surface of superconducting Cu(x)Bi(2)Se(3) present a zero-bias conductance peak (ZBCP) which signifies unconventional superconductivity. Theoretical considerations of all possible superconducting states help us conclude that this ZBCP is due to Majorana fermions and gives evidence for a topological superconductivity in Cu(x)Bi(2)Se(3). In addition, we found an unusual pseudogap that develops below ～20 K and coexists with the topological superconducting state.     

N(2)-Broadening Coefficients in the nu(1) Band of (35)Cl(12)C(14)N

N(2)-broadening coefficients have been measured for 30 lines of cyanogen chloride ((35)Cl(12)C(14)N) at room temperature in the P and R branches of the nu(1) band, using a tunable diode-laser spectrometer. These lines, with J values ranging from 0 to 55, are located in the spectral range 694-736 cm(-1). The collisional widths are obtained by fitting the spectral lines with a Voigt and a Rautian profile. The broadenings coefficients of (35)ClCN-N(2) have also been calculated from a semiclassical theory involving the atom-atom Lennard-Jones model for the intermolecular potential in addition to electrostatic interaction. Copyright 2000 Academic Press.     

The (29)Si T(1) and T(2) NMR relaxation in porous paramagnetic material SiO(2)-MnO-Al(2)O(3)

The (29)Si spin-lattice relaxation in porous silica-based material 1, doped by ions Mn(2+) at a Si/Mn ratio of 3.5, is non-exponential, independent of magic-angle spinning (MAS) rates and governed by direct dipolar coupling between electron and nucleus where an electron relaxation time is estimated to be about 10(-8)s. In the absence of mutual energy-conserving spin flips (spin diffusion) in 1, the (29)Si T(2) time increases linearly with spinning rates. None was observed in diamagnetic porous system 2. The unexpected (29)Si T(2) dependence has been interpreted in terms of the large bulk magnetic susceptibility (BMS) effects. It has been shown that editing the (29)Si Hahn-echo MAS NMR spectra eliminates wide lines, belonging to (29)Si nuclei in the proximity of paramagnetic centers, and reduces the BMS broadenings in sideband patterns for nuclei remote from these centers.