Massive Form Research Articles

Recovery of locked-up uranium in slag disc by co-melting in magnesio-thermic reduction

Magnesio-thermic Reduction (MTR) of Uranium tetra Fluoride (UF4) is one of the main industrial methods for producing commercial pure uranium metal in massive form. Nuclear grade natural Uranium (U) metal ingots are produced regularly in UED, BARC following MTR route for fuelling research reactors in BARC. This is a bomb type reaction and is represented by $$UF_4 + 2Mg = U + 2MgF_{2 - } (\Delta H^ \circ _{298} = - 83.5 Kcal/gm mole)$$ Small excess of magnesium is required to achieve maximum yield. This thermite type reduction is carried out in a closed reaction vessel, popularly known as MTR reactor, lined with magnesium fluoride powder. MTR reactors are made of boiler quality steel. Use of MgF2, a reaction by-product, as lining material completely eliminates the chance of foreign element contamination. This lining of MgF2 not only prevents direct contact of the molten metal and slag with the reaction vessel but also acts as an insulating material immediately after firing and holds the hot molten mass for longer period, thereby facilitating adequate metal-slag separation. This is a batch process and stoichiometric quantity of UF4 and Mg chips are blended and charged inside the lined reactor. Once the charging is over, the surface is covered with fine MgF2 powder and sealed by fixing a lid. This sealed reactor is then heated inside an electric furnace at a predefined heating schedule for the reduction to take place. The initiation of reaction is called ‘Firing”.

Spatial structure of coral reef fish communities at Kudaka Island (Ryukyu Archipelago), Japan

The present study aimed to investigate the spatial structure of fish communities at juvenile and adult stages on coral reefs at Kudaka Island (Ryukyu Archipelago, Japan) and to relate spatial patterns in the structure of the fish communities to gradients in environmental variables. Diurnal visual censuses allowed us to record 2,602 juveniles belonging to 60 species and 1,543 adults belonging to 53 species from October to December 2005. The distribution of species highlighted that the juvenile community was organised into three distinct assemblages, rather than exhibiting gradual change in community structure along the cross-reef gradient. Correlations between spatial patterns of juvenile community and environmental variables revealed that the most significant factors explaining variation in community structure were coral rubble and coral slab. In contrast, the adult community was organised into one assemblage, and the most significant variation factors in community structure were depth, live coral in massive form, live coral in branched form, dead coral and sand. Overall, the present study showed that most juvenile and adult coral reef fish at Kudaka Island exhibited striking patterns in their distribution and depth and some biological factors (e.g., abundance of live coral, dead coral and coral rubble) might exert considerable influence on the distribution of fishes.

Vosmaeria Fristedt, 1885 (Porifera, Demospongiae, Halichondriidae): revision of species, phylogenetic reconstruction and evidence for split

All species of Vosmaeria are re-described using type and additional material. The phylogenetic relationships between Vosmaeria ssp. and other demosponge taxa are reconstructed based on 28S-rDNA sequences analyses. V. crustacea, the type species, is widely distributed in the NE Atlantic and characterized by a thinly encrusting growth form, the location of ostia and oscula exclusively on papillae, a dense and firm ectosomal skeleton, the absence of subectosomal aquiferous cavities and the blunt distal tips of tylostyles. Hydrochemical conditions may account for the smaller spicule size of the White Sea population compared to those in the North and Barents Sea. V. reticulosa, known from the Chilean and Peruvian coasts, is distinguished by a massive growth form, a reticulated ectosomal skeleton, the absence of papillae, the scattering of ostia and oscula over the surface, the presence of subectosomal cavities and the acerate distal tips of tylostyles. V. levigata, known exclusively from the English Channel, shares the absence of papillae and the acerate distal tips of tylostyles with V. reticulosa, but the only surviving material consists of dissociated spicules slides, and consequently its status remains unclear. On the basis of substantial morphological differences we propose to split Vosmaeria into two monospecific genera – Vosmaeria, with type species V. crustacea, and Johannesia gen. nov., with type species V. reticulosa. Both genera clearly belong to Halichondriidae based on the tangential arrangement of the ectosomal skeleton, the presence of oxeas. Molecular phylogenetic analyses support a split into two genera and confirm the classification of both within the Halichondriidae.

Two new sponges of the genus halichondria (halichondrida: Halichondriidae) from Korea

Two new marine sponges in the family Halichondriidae, Halichondria gageoenesis n. sp. and Halichondria muanensis n. sp. are collected from Gageodo Island and Yongjeong‐ri, Hyeongyeong‐myeon, Muan‐gun, Korea during 2006–2007. H. gageoenesis n. sp. is similar to H. oshoro (Tanita, 1961) in type of spicule, but is different from the latter in growth form and size of spicule. The oxea of the new species is larger than H. oshoro's. The growth form of H. gageoenesis n. sp. is thick and consists of encrusting with numerous erect hollow cylindrical tubes, but H. oshoro is of massive form. H. muanensis n. sp is similar to H. retiderma (Dendy, 1921) in type of spicule and choanosomal skeleton, but it is different from the latter in growth form and size of spicule. The oxea is smaller than that of H. retiderma. The growth form is thick and consists of encrusting, with numerous erect hollow cylindrical tubes, compared with the massive lobose of H. retiderma.

Investigation of Manganese Mineralization in Idahlu and Jokandy, Southwest of Hashtrood, NW Iran

The purpose of this study is to determine the genesis of the manganese indexes around the Hashtroud city, with special regard to Idahlu-Jokandy region. In this region Mn mineralization is sparse and rather extensive. Its origin is from hot springs and precipitated on the earth surface. The mineralization is mainly massive and vein form. Due to presence of hot springs and their traces in the studied area, it can be concluded that Fe and Mn components have participated in the hot springs and by these springs, they have precipitated superficially or penetrated into existing fractures and faults of the region's rocks and caused to mineralization. The main Mn minerals are pyrolusite and psylomelane, accompanied by gypsum, travertine, barite and jasper.

Two New Microcionid Sponges (Poecilosclerida: Microcionidae) from Taedo Island, Korea

Two new marine sponges, Clathria (Clthria) jungtaedoensis n. sp. and Antho (Antho) hataedoensis n. sp. were collected in Taedo Island, Korea. C. (C.) jungtaedoensis n. sp. is similar to C. (C.) striata. The new species, however, has many small toxa and massive form. A. (A.) hataedoensis n. sp. is similar to A. (A.) inconstans from Gulf of Naples, Italy, but differs from the latter in the size of spicules. The toxa in the new species is about one third as long as A. (A.) inconstans's.

Relating species traits to environmental variables in Indonesian coral reef sponge assemblages

A key goal in ecology is to understand how species with given traits vary with changing environmental conditions. In the Spermonde Archipelago, Indonesia, we identified environmental gradients associated with significant variation in sponge species traits. These were (1) an on-to-offshore gradient, (2) a gradient from locally perturbed reef sites characterised by fluctuating sediment load concentrations and poor water transparency to locally pristine sites characterised by good water transparency and (3) a depth gradient. Species with a massive growth form were associated with inshore reef environments, whereas species with a cup growth form were linked to offshore reefs with a high coral cover. Weakly bioactive species and species with a globular, fan or fistulose growth form were associated with locally perturbed reef environments as indicated by fluctuating sediment levels and reduced water transparency, whereas strongly bioactive species and species with a massive-encrusting and tube growth form were associated with more pristine reef environments with good water transparency. With respect to depth, oviparous species and species with a cup and massive growth form were most strongly associated with deeper transects, whereas species with a ramose, massive creeping and massive-encrusting growth form were most strongly associated with shallower transects. Results of the present study indicate that environmental conditions and species traits interact to determine the composition of sponges across coral reefs.

Spongia (Heterofibria) catarinensis sp. nov. (Porifera, Spongiidae) no litoral de Santa Catarina, Brasil

Uma nova espécie, Spongia (Heterofibria) catarinensis, é descrita para a Ilha das Aranhas (27º29'077''S, 48º21'380''W), Estado de Santa Catarina, Brasil. Difere das outras espécies do gênero do Atlântico sudoeste pela morfologia externa e arquitetura. A nova espécie é caracterizada por apresentar forma massiva, incrustante com projeções lobulares; fibras primárias medindo 60-100 µm; fibras secundárias 11,5-69 µm; fibras pseudoterciárias 2,3-23 µm e distância entre fibras primárias 391-920 µm; distância entre fibras secundárias/pseudoterciárias 92-575 µm; fibras secundárias/pseudoterciárias constituindo malhas poligonais com 30-700 µm de diâmetro. A espécie pertence ao subgênero Heterofibria Cook & Bergquist, 2001 por apresentar uma clara dicotomia de suas fibras.

Giant sand waves at the mouth of San Francisco Bay

A field of giant sand waves, among the largest in the world, recently was mapped in high resolution for the first time during a multibeam survey in 2004 and 2005 through the strait of the Golden Gate at the mouth of San Francisco Bay in California (Figure la). This massive bed form field covers an area of approximately four square kilometers in water depths ranging from 30 to 106 meters, featuring more than 40 distinct sand waves with crests aligned approximately perpendicular to the dominant tidally generated cross‐shore currents, with wavelengths and heights that measure up to 220 meters and 10 meters, respectively.Sand wave crests can be traced continuously for up to two kilometers across the mouth of this energetic tidal inlet, where depth‐averaged tidal currents through the strait below the Golden Gate Bridge exceed 2.5 meters per second during peak ebb flows. Repeated surveys demonstrated that the sand waves are active and dynamic features that move in response to tidally generated currents. The complex temporal and spatial variations in wave and tidal current interactions in this region result in an astoundingly diverse array of bed form morphologies, scales, and orientations. Bed forms of approximately half the scale of those reported in this article previously were mapped inside San Francisco Bay during a multibeam survey in 1997 [Chin et al., 1997].

A new Mediterranean ‘lithistid’ sponge, Aciculites mediterranea sp. nov. (Porifera: Demospongiae) from a dark marine cave in Sardinia

A first record of the genus Aciculites in the Mediterranean Sea and the description of Aciculites mediterranea sp. nov. are here presented from a faunistic survey in a dark shallow marine cave of the north-western Sardinian karstic area. The new species is characterized by a massive cerebellum-like growth form, and a peculiar distribution of inhalant and exhalant areas, respectively, in depressed and elevated portions of the sponge surface. Oscules show a long narrow atrial cavity. Ectosomal skeleton is made of tangential anisostrongyles on elevated areas, and more or less vertical tufts of anisostrongyles in depressed inhalant areas. Anisostrongyles are smooth or with tips ornated by irregular tubercles. Sigmaspire microscleres are lacking. Choanosomal skeleton with tubercled irregular rizhoclone desmas and few scattered and variably oriented anisostrongyles. A comparative analysis of Aciculites mediterranea sp. nov. versus morphological diagnostic traits, geographical range and habitat of the species hitherto ascribed to Aciculites confirms that the peculiar distribution of the genus supports its relic condition of an ancient Tethyan fauna in the Mediterranean Sea.

Bacterial desulphurization of coal from mine CSA Most

The objective of the paper was application of bacterial leaching on 3 brown coal samples from bore S 187 (CV) from locality Mine CSA Most. Based on the results of bacterial leaching and petrologic analyses of the given samples, it is possible to state that the individual samples are very similar, they contain significant shares of clay materials and pyrite is predominantly represented in a framboidal form, which intergrowths into a massive form. Applying bacterial leaching it is possible to remove from 24 to 40% of total sulphur and from 20 to 37% of pyritic sulphur from the coals.

Israeli Backpacking Since the 1960s: Institutionalization and its Effects

This article explores empirical and theoretical aspects concerning the heightened state of institutionalization of backpacking tourism. The exploration is accomplished through examining the evolution of Israeli backpacking in Asia and South America over the past four decades, and the effects of institutionalization on the tourist experience. From a theoretical perspective, the article seeks to illustrate modern processes of institutionalization through a conceptualization of three, interrelated dimensions: changes in the personal experience, social and cultural vicissitudes in social systems, and organizational processes. From an empirical point of view, these dimensions are considered across three phases of evolution, during which they have undergone significant concomitant changes. This has resulted in the gradual transformation of backpacking from a liminal and marginal practice, in which few alienated individuals participated during the sixties of the twentieth century, to a massive and normative form of a touristic rite of passage in contemporary Israeli society.

Multifactorial study of prognostic factors in differentiated thyroid carcinoma and a re-evaluation of the importance of age.

A multivariate analysis of prognostic factors has been carried out with 375 cases of differentiated thyroid cancer (DTC) treated in the same centre by total thyroidectomy and 131I therapy. The patients have been followed for 5 to 23 years. The isolated prognostic roles of age, sex, clinical stage and histology were confirmed, but these factors were found to be strongly interrelated. Multifactorial analysis was conducted following Cox's model. It demonstrated that the prevalent role of clinical staging (nodular versus lobar or massive form) is as important as the initial presence of metastases (P = 0.0001). Histological assessment of differentiation, age and sex were of lesser importance. Thus, the most significant prognostic variable is clinical stage. These data must be taken into account when formulating management protocols for DTC.

Calathiscus tantillus, a new genus and new species of scleractinian coral (Scleractinia, Poritidae) from the Gulf of Oman

Calathiscus tantillus new genus & new species (Scleractinia, Poritidae) is described from several specimens collected along the north coast of the Sultanate of Oman and Masirah Island. The zooxanthellate genus has a massive growth form, although colonies remain very small (< 40 mm). The skeletal characteristics are intermediate between Porites and Goniopora, with calices averaging 1.7 mm in diameter. The polyps, fully extended during the day in most specimens, have a long tubular column topped by a wide conical oral disc surrounded by 15 22 tentacles. The characteristics of this new species and genus are discussed in relation to other genera in the family: Porites, Goniopora, Stylarea, Alveopora and Poritipora.

Electric charge and magnetic moment of a massive neutrino

We consider the massive Dirac neutrino electric charge and magnetic moment within the context of the standard model supplied with an SU(2)-singlet right-handed neutrino in an arbitrary ${R}_{\ensuremath{\xi}}$ gauge. Using the dimensional-regularization scheme we start with the calculations of the one-loop contributions to the neutrino electromagnetic vertex function exactly accounting for the neutrino mass. We examine the decomposition of the massive neutrino electromagnetic vertex function. It is found by means of direct calculations that the massive neutrino vertex function contains only the four form factors. Then we derive the closed integral expressions for different contributions to the neutrino electric form factor, electric charge, and magnetic moment. For several one-loop contributions to the neutrino charge and magnetic moment that were calculated previously with mistakes by the other authors, we find the correct results. We show that the electric charge for the massive neutrino is a gauge independent and vanishing parameter in the first two orders of the expansion over the neutrino mass parameter ${b=(m}_{\ensuremath{\nu}}{/M}_{W}{)}^{2}.$ From the obtained closed two-integral expression for a massive neutrino electric form factor it is also possible to derive the neutrino charge radius. In the particular choice of the 't Hooft--Feynman gauge we also demonstrate that the neutrino charge is zero in all orders of expansion over b, i.e., for an arbitrary mass of neutrino. For each of the diagrams contributing to the neutrino magnetic moment, we obtain the expressions accounting for the leading (zeroth) and next-to-leading (first) order in b, where the gauge dependence is shown explicitly. Each of the contributions is finite and the sum of all contributions turns out to be gauge independent. Our calculations also enable us to obtain the neutrino magnetic moment in theoretical models that differ from each other by the values of particles' masses, including the case of a very heavy neutrino. The general expression for the massive neutrino magnetic form factor is presented.

Compactifications with S-duality twists

We consider generalised Scherk Schwarz reductions of supergravity and superstring theories with twists by electromagnetic dualities that are symmetries of the equations of motion but not of the action, such as the S-duality of D=4, N=4 super-Yang-Mills coupled to supergravity. The reduction cannot be done on the action itself, but must be done either on the field equations or on a duality invariant form of the action, such as one in the doubled formalism in which potentials are introduced for both electric and magnetic fields. The resulting theory in odd-dimensions has massive form fields satisfying a self-duality condition $dA \sim m*A$. We construct such theories in D=3,5,7.

Hepatic fascioliasis in the Americas: A new challenge for therapeutic endoscopy

Hepatic fascioliasis in the Americas: A new challenge for therapeutic endoscopy

A weak, attractive, long-range force in Higgs condensates

Due to the peculiar nature of the underlying medium, density fluctuations in a ‘Higgs condensate’ are predicted to propagate for infinitely long wavelengths with a group velocity c s →∞. On the other hand, for any large but finite c s there is a weak, attractive 1/ r potential of strength 1/ c 2 s and the energy spectrum deviates from the purely massive form p 2+M 2 h at momenta smaller than δ∼ M h / c s . Physically, the length scale δ −1 corresponds to the mean free-path for the elementary constituents in the condensate and would naturally be placed in the millimeter range.

The effect of microstructure on hardness measurements in the aluminium-rich corner of the Al–Ni–Cr system

Arc-melted Al-rich samples from the Al–Cr–Ni system were analysed using optical microscopy, scanning electron microscopy, energy dispersive X-ray spectroscopy and X-ray diffraction. All of the expected binary phases were observed and identified. The binary phase with the largest extension into the ternary was Al 3Ni 2 at about 12 at.%. Three separate ternary phases were identified from the microstructures, and were found to agree reasonably with the compositions in the literature, although the phase fields had different shapes. Vicker’s microhardness measurements have indicated that the phase hardnesses in decreasing order are most likely: Al 3Ni 2, φ, (αCr), ρ, Al 4Cr, Al 7Cr, Al 11Cr 2, Al 9Cr 4, Al 3Ni and (Al). The φ, Al 4Cr, Al 11Cr 2 and Al 3Ni phases were brittle in massive form.

Pueblo Mission Churches as Symbols of Permanence and Identity

The three Pueblo mission churches of San Esteban del Rey, Nuestra Señora de Guadalupe, and San José de Laguna are the most visually striking structures in the western New Mexico pueblos of Acoma, Zuni, and Laguna. Prime examples of “structures of permanence” on the landscape, the churches define local cultural identity. Church permanence and Pueblo identity are expressed in a five‐part typology of visible characteristics: natural materials and hand labor, massive exterior form, adjoining cemeteries, syncretism of interior decorations, and structural decay and rebirth. Permanence must, however, be understood as an evolving condition, undergoing new representations as multicultural relationships evolve.