bluuebunny/crossref_metadata_2025 huggingface dataset:
Basaltic pahoehoe lava-fed deltas: large-scale characteristics, clast generation, emplacement processes and environmental discrimination
Authors: Skilling I. P.
Published: September 2007

Basaltic pahoehoe lava-fed deltas are important coastal constructions of many oceanic islands and continental flood basalt provinces. Whilst littoral processes associated with their formation have been described, little is known about subaqueous processes and products. This study is primarily focused on field studies of lava-fed deltas from the James Ross Island Volcanic Group (JRIVG), Antarctica, but also on other published studies of lava-fed deltas, and on information from studies of coarse-grained alluvial deltas. Seven coherent lava facies and eight subaqueously deposited clastic facies from the JRIVG are described and interpreted. Clastic facies are dominated by cobble-sized angular lithic and fluidal lithic-vitric breccias. The fluidal lithic-vitric breccias are derived from various slope failure processes acting on large-volume ponded lavas in the frontal crest area, or from gravity-driven ductile detachment of the margins of active pillow and sheet lavas on the steep subaqueous slope. Angular lithic breccias are generated mostly by similar brittle processes operating on cooled and jointed lavas ponded upslope. Subaqueous emplacement is mostly by density-modified grain flows with associated small buoyant plumes of finer sediment, and by high-density turbidity currents, many of which infill debris chutes. Basaltic lava-fed deltas have large-scale characteristics and processes that are similar to those of Gilbert-type and gravitationally-modified Gilbert-type alluvial deltas. Important contrasts that influence processes and facies in lava-fed deltas include the absence of any effluent force and the presence of hot clasts. Study of lava-fed delta deposits is important for palaeoenvironmental analysis because marine examples record relative sea level changes, and englacial examples provide evidence of minimum ice sheet thicknesses and meltwater levels. Characteristics that may be used to distinguish lava-fed deltas in marine and englacial lake environments are discussed, and littoral zone facies analysis is emphasized. Suggestions for future research include correlation of the physical parameters of subaerial and subaqueous lavas and the nature of cogenetic clastic products, submersible dives on active deltas, detailed facies analysis of individual tangential foreset beds, and comparative studies with steep coarse-grained alluvial deltas.
Physical volcanology of a subglacial-to-emergent rhyolitic tuya at Rauðufossafjöll, Torfajökull, Iceland
Authors: Tuffen H. , McGarvie D. W. , Gilbert J. S. , Pinkerton H.
Published: September 2007

This paper presents the first modern volcanological study of a subglacial-to-emergent rhyolite tuya, at SE Rauðufossafjöll, Torfajökull, Iceland. A flat-topped edifice with a volume ofc.1 km3was emplaced in Upper Pleistocene time beneath a glacier >350m thick. Although it shares morphological characteristics with basaltic tuyas, the lithofacies indicate a very different eruption mechanism.

Field observations suggest that the eruption began with vigorous phreatomagmatic explosions within a well-drained ice vault, building a pile of unbedded ash up to 300m thick. This was followed by a subaerial effusive phase, in which compound lava flows were emplaced within ice cauldrons. Small-volume effusive eruptions on the volcano flanks created several lava bodies, with a variety of features (columnar-jointed sides, subaerial tops, peperitic bases) that are used to reconstruct spatially-heterogeneous patterns of volcano-ice interaction. Volcaniclastic sediments exposed in a stream section provide evidence for channelised meltwater drainage and fluctuating depositional processes during the eruption.

Models are developed for the evolution of SE Rauðufossafjöll, and the differences between subglacial rhyolitic and basaltic eruption mechanisms, which are principally caused by contrasting hydrological patterns, are discussed.
Rootless cones on Mars: a consequence of lava-ground ice interaction
Authors: Fagents S. A. , Lanagan P. , Greeley R.
Published: September 2007

Fields of small cratered cones on Mars are interpreted to have formed by rootless eruptions due to explosive interaction of lava with ground ice contained within the regolith beneath the flow. Melting and vaporization of the ice, and subsequent explosive expansion of the vapour, act to excavate the lava and construct a rootless cone around the explosion site. Similar features are found in Iceland, where flowing lavas encountered water-saturated substrates. The martian cones have basal diameters of
c
. 30–1000 m and are located predominantly in the northern volcanic plains. High-resolution Mars Orbiter Camera images offer significant improvements over Viking data for interpretation of cone origins. A new model of the dynamics of cone formation indicates that very modest amounts of water ice are required to initiate and sustain the explosive interactions that produced the observed features. This is consistent with the likely low availability of water ice in the martian regolith. The scarcity of impact craters on many of the host lava flows indicates very young ages, suggesting that ground ice was present as recently as <10–100 Ma, and may persist today. Rootless cones therefore act as a spatial and temporal probe of the distribution of ground ice on Mars, which is of key significance in understanding the evolution of the martian climate. The location of water in liquid or solid form is of great importance to future robotic and human exploration strategies, and to the search for extraterrestrial life.
Deterioration of the Globigerina Limestone of the Maltese Islands
Authors: Cassar Joann
Published: September 2007

The Globigerina Limestone occurs as two types of building stone: the resistant ‘franka’ and the easily weathering ‘soll’. Research on both fresh and weathered samples has led to an understanding of the main differences in these two types of stone. The causes and mechanisms of deterioration have also been established. ‘Franka’ and ‘soll’ differ in geochemical and mineralogical composition and in physical properties. The ‘soll’ is richer in the non-carbonate fraction, which occludes some of the pore space, resulting in a lower overall porosity and a higher proportion of small pores. The ambient local environment, heavily loaded with sea salt, particularly sodium chloride and sulphates, readily induces deterioration in ‘soll’, whereas ‘franka’ tends to resist better in this aggressive environment. The weathering process of Globigerina Limestone in general has been explained as a sequence of steps, from the formation of a thick and compact superficial crust, to the loss of this crust, to the initiation of alveolar weathering. Understanding the deterioration mechanisms of Globigerina Limestone permits criteria for proper conservation treatment to be established.
Ultrasonic wave velocities as a diagnostic tool for the quality assessment of marble
Authors: Weiss T. , Rasolofosaon P. N. J. , Siegesmund S.
Published: September 2007

Marbles are frequently used as building stones even if they mostly show a limited durability. Thus, different marbles with different fabric types and states of preservation have been investigated in order to constrain the interaction between fabric, state of deterioration and ultrasonic wave velocities. Experimental data reveal that the state of preservation of a marble is clearly documented by ultrasonic wave velocities of compressional waves. For a maximum porosity of up to 1% velocities determined on dry samples range from about 1 km s
−1
to over 6 km s
−1
. Anisotropy of ultrasonic wave velocities is a common feature of marbles due to a lattice preferred orientation of the anisotropic rock-forming minerals calcite and dolomite. Pre-existing and thermally induced microcracks tend to increase this anisotropy. For Lasa marble, this increase can be explained by a coincidence of intrinsic anisotropy and the effect of pre-existing and thermally induced microcracks. For many marbles, velocities are reduced to at about 1 km s
−1
as a consequence of thermal degradation due to only one heating cycle up to 100°C. Model calculations reveal that the velocity reduction is caused by cracks with an extremely small aspect ratio of about 0.005 or even less. The porosity associated with this very early stage of deterioration will not be increased significantly and thus, thermal degradation cannot be determined by other petrophysical measurements.
Bending strength properties of untreated and impregnated igneous, sedimentary and metamorphic dimension stones of different thickness
Authors: Sahlin T. , Stigh J. , Schouenborg B.
Published: September 2007

A production method has been developed that makes it possible to produce dimension stone tiles only 4 mm thick without high amounts of waste material. The tiles are impregnated with a mixture of potassium-based water-glass, water, colloidal silica, and Berol 048 (non-ionic surfactant), using a repeated cycling between vacuum and atmospheric pressure. Mineralogy, fabric, and porosity affect the mechanical properties of rock used as dimension stone in the building industry. Tests for bending strength have been performed on tiles of eight different untreated and impregnated samples of igneous, sedimentary, and metamorphic rocks. Samples of three different thicknesses (4, 7 and 10 mm) were used in the tests. The untreated rock samples that had a fine-grained texture, low crack density, high mafic mineral content or a distinct ductile metamorphic texture showed the highest bending strength values, whereas those that had high amounts of carbonate minerals, and high crack or void density exhibited the lowest values. The stone types that gained the most from impregnation, in general, were those with high crack or void density.
Atmospheric pollution and building materials: stone and glass
Authors: Lefèvre R. A. , Ausset P.
Published: September 2007

The research carried out by LISA on the decay of stone and glass by atmospheric pollution is presented. On building facades, areas unsheltered from rain are clear and eroded, while those that are sheltered darken due to the development of black crusts containing anthropogenic particles (fly-ash, soot) cemented by a framework of gypsum crystals. On calcareous stones, in-depth sulphation of the stone substrate may also occur at the same time. On porous calcareous stones, the black crusts detach periodically forming black slabs, creating a white, grey and black jigsaw-like pattern on the remaining stone surface. By exposing stone test samples to field and/or laboratory controlled polluted atmospheric conditions, the formation of embryonic black crusts has been observed. Grey crusts developed during pre-industrial times have been found to contain unburnt wood debris as a record of past air pollution. Glass alters by leaching, corrosion, encrusting and soiling. The quantification of the effects of atmospheric pollution can be accomplished either directly on buildings of different ages, or through field and/or laboratory controlled experiments. Modelling of the alteration of materials by atmospheric pollution consists of the determination of dose-response functions, of acceptable levels and thresholds and in risk assessment mapping.
Modelling the rapid retreat of building sandstones: a case study from a polluted maritime environment
Authors: Smith B. J. , Turkington A. V. , Warke P. A. , Basheer P. A. M. , McAlister J. J. , Meneely J. , Curran J. M.
Published: September 2007

Sandstones are widely used as building stones throughout NW Europe. Unlike limestone, sandstones tend to experience episodic and sometimes rapid surface retreat associated with the action of salts and often leading to the development of hollows/caverns in the stone. The unpredictability of these decay dynamics can present significant problems when planning conservation strategies. Consequently, successful conservation requires a better understanding of the factors that trigger decay and determine the subsequent decay pathway. An overview of results from previous studies provided the basis for simulation experiments aimed at identifying the factors that (a) initiate decay and (b) permit the continuance of salt weathering despite rapid loss of surface material. These simulation studies involve investigation of changes in micro-environmental conditions as surface hollows develop and examination of salt weathering dynamics within such hollows. These data combined with knowledge gained from previous work have allowed the refinement of a conceptual model of rapid sandstone retreat. In this model decay is linked to the establishment of positive feedback conditions through interactions between factors such as porosity, permeability, mineralogy and their effect on salt penetration.
Oolitic limestone in a polluted atmospheric environment in Budapest: weathering phenomena and alterations in physical properties
Authors: Török Ákos
Published: September 2007

In Budapest damage due to atmospheric pollution on many public buildings is severe. Black encrustations, white crusts and other decay features of a soft oolitic limestone have been studied in detail by using field measurements and laboratory analyses. Limestone weathering was assessed by description of weathering forms, by on-site petrophysical tests (Duroscope, Schmidt hammer, water absorption) and by laboratory mineralogical assessment and thermoanalysis (X-ray diffraction, Derivatograph). There is a clear correlation between the organic carbon content in stone and location of the site, particularly in the polluted city centre. Gypsum, which is not an indigenous mineral in the limestone, can contribute up to 70% of the crust composition and indicates the importance of air-derived SO
2
. This mineralogical change in stone composition leads to changes in physical properties, by strengthening laminar black crusts and white case hardened crusts and weakening the host rock.
Acid deposition and the deterioration of stone: a brief review of a broad topic
Authors: Charola A. Elena , Ware Robert
Published: September 2007

The causes of stone deterioration due to acid deposition are examined, with specific reference made to important research on this subject from the past thirty years. The major topics covered include: dry deposition of atmospheric pollutants, the primary agent of acid deterioration of stone in urban areas; wet deposition, commonly referred to as acid rain; and major deterioration mechanisms. Key factors are dry deposition of gaseous pollutants such as SO
2
and NOx, the nature of the stone, including texture and porosity, and the presence of moisture on its surface as well as the ‘time of wetness’.
Evaluation of the origin of sulphate compounds in building stone by sulphur isotope ratio
Authors: Klemm Werner , Siedel Heiner
Published: September 2007

Sulphate salts are a main factor in the deterioration of building materials such as natural stone, mortar, plaster and brick. Although environmental pollution is the main source for the formation of sulphate salts on historical monuments in Central Europe, for more detailed investigations into the reasons for salt formation on specific buildings more precise information about the sources and the transport paths is needed. Sulphur isotope analyses seem to be a useful tool for the characterization of various sources of sulphur in the natural as well as in the anthropogenic environment relevant to salt formation on monuments. Investigations in the southern part of East Germany with extreme environmental pollution until 1990 should demonstrate the advantages and limits of the method. Environmental influences are the main factor for sulphate salt formation at historical monuments in this area. In special cases other sources such as groundwater or building materials are relevant for salt formation. At a regional scale, the δ
34
S values for salts and crusts on monuments scatter over a broad range (between +2 and +10‰ in the investigated area). Nevertheless, for special locations or monuments the number of possible sources of sulphur can be minimized if δ
34
S values for all relevant influences such as building materials, groundwater and the specific environmental influences (rainwater, dust, SO
2
) are available.
Kinematics of the East African Rift from GPS and earthquake slip vector data
Authors: Calais E. , Ebinger C. , Hartnady C. , Nocquet J.M.
Published: September 2007

Although the East African Rift (EAR) System is often cited as the archetype for models of continental rifting and break-up, its present-day kinematics remains poorly constrained. We show that the currently available GPS and earthquake slip vector data are consistent with (1) a present-day Nubia-Somalia Euler pole located between the southern tip of Africa and the Southwest Indian ridge and (2) the existence of a distinct microplate (Victoria) between the Eastern and Western rifts, rotating counter-clockwise with respect to Nubia. Geodetic and geological data also suggest the existence of a (Rovuma) microplate between the Malawi rift and the Davie ridge, possibly rotating clockwise with respect to Nubia. The data indicate that the EAR comprises at least two rigid lithospheric blocks bounded by narrow belts of seismicity (<50 km wide) marking localized deformation rather than a wide zone of quasi-continuous, pervasive deformation. On the basis of this new kinematic model and mantle flow directions interpreted from seismic anisotropy measurements, we propose that regional asthenospheric upwelling and locally focused mantle flow may influence continental deformation in East Africa.
Strain accommodation in transitional rifts: extension by magma intrusion and faulting in Ethiopian rift magmatic segments
Authors: Casey M. , Ebinger C. , Keir D. , Gloaguen R. , Mohamed F.
Published: September 2007

Active deformation within the northern part of the Main Ethiopian Rift (MER) occurs within approximately 60 km-long, 20 km-wide ‘magmatic segments’ that lie within the 80 km-wide rift valley. Geophysical data reveal that the crust beneath the <1.9 Ma magmatic segments has been heavily intruded; magmatic segments accommodate strain via both magma intrusion and faulting. We undertake field and remote sensing analyses of faults and eruptive centres in the magmatic segments to estimate the relative proportion of strain accommodated by faulting and magma intrusion and the kinematics of Quaternary faults. Up to half the ≤10 km-long normal faults within the Boset-Kone and Fantale-Dofen magmatic segments have eruptive centres or extrusive lavas along their length. Comparison of the deformation field of the largest Quaternary fault and an elastic half-space dislocation model indicates a down-dip length of 10 km, coincident with the seismogenic layer thickness and the top of the seismically imaged mafic intrusions. These relations suggest that Quaternary faults are primarily driven by magma intrusion into the mid- to upper crust, which triggers faulting and dyke intrusion into the brittle upper crust. The active volcanoes of Boset, Fantale and Dofen all have elliptical shapes with their long axes in the direction N105, consistent with extension direction derived from earthquake focal mechanisms. Calderas show natural strains ranging from around 0.30 for Boset, 0.55 for Fantale, and 0.94 for Dofen. These values give extension strain rates of the order of 0.3 microstrain per year, comparable to geodetic models. Structural analyses reveal no evidence for transcurrent faults linking right-stepping magmatic segments. Instead, the tips of magmatic segments overlap, thereby accommodating strain transfer. The intimate relationship between faulting and magmatism in the northern MER is strikingly similar to that of slow-spreading mid-ocean ridges, but without the hard linkage zones of transform faults.
Vertical deformation in the Main Ethiopian Rift: levelling results in its northern part, 1995–2004
Authors: Asfaw Laike M. , Beyene Henok , Mkonnen Amde , Oli Tadesse
Published: September 2007

A levelling line consisting of 43 benchmarks was established between the towns of Wolenchiti and Metehara in the northern part of the Main Ethiopian Rift in July 1995 by the Geophysical Observatory of Addis Ababa University and the Ethiopian Mapping Authority. The measurement was repeated in November 2003 on 30 of the surviving benchmarks. In both epochs of measurement, the standard accuracy attained is ± 4 mm √K corresponding to a first order levelling, where
K
is the inter-benchmark distance in kilometres. The line crosses the northern and southern parts of the Nazret (Boset-Kone) and Sabure (Fantale-Dofen) magmatic segments respectively where 80% of rift deformation is believed to be localized. In eight years, interval height differences ranging from +3 mm to −22 mm are found along the line with the maximum subsidence rate of 2.8 mm a
−1
corresponding to the Kone-Gariboldi volcanic complex in the northern part of the Nazret magmatic segment. On the other hand, at the eastern end of the line, despite the existence of large fissures and an expanding lake in the vicinity suggesting possible significant subsidence, on the contrary relatively small vertical deformation is found. The strong subsidence measured at the Kone-Gariboldi volcanic complex is interpreted to be due to remnant processes of subsidence at these volcanic centres following withdrawal of magma in the recent past. Regarding the eastern end of the line where Lake Beseka is located, the result is particularly important in verifying that the rapid expansion of the lake associated with elevation increase of 40 cm a
−1
could not be attributed to tectonic subsidence or uplift in the region.
Dynamics of prolonged continental extension in magmatic rifts: the Turkana Rift case study (North Kenya)
Authors: Vetel William , Le Gall Bernard
Published: September 2007

The Turkana magmatic rift (Northern Kenya) initiated at 45 Ma as one of the nucleation zones of rifting in the East African Rift. It forms an anomalously broad-rifted zone (
c.
200 km) striking with a north-south trend and lying within a NW-SE topographic depression, floored on both sides of the Turkana area by Cretaceous rifts in the Sudan and Anza plains. From a compilation of available data, combined with newly acquired remote sensing and DEM dataset, we propose a five-stage tectono-magmatic model for the Turkana rift evolution (45–23 Ma; 23–15 Ma; 15–6 Ma; 6–2.6 Ma and 2.6 Ma-Present). The corresponding ‘restored’ maps clearly show the changing spatial distribution of magmatism and fault/basin network with time, hence supplying some clues about dynamics of continental extension. First-order basement-rooted transverse faults zones are identified and their influence on nucleation and propagation of strain is demonstrated, whereas the role of magmatic ‘soft-spots’ as concentrating strain is minimized. Blocking of deformation as well as rift jump and lateral transfer of strain are discussed in relation to various types of fault interaction (dip direction, strikes and acute/obtuse angle of the intersecting faults). The causal links between rift nucleation ‘cells’ and inherited transverse weakness zones in the Turkana rift might also exist elsewhere along the eastern branch of the East African Rift, hence suggesting a complex and discontinuous mode of rift propagation.
New constraints on crustal structure in eastern Afar from the analysis of receiver functions and surface wave dispersion in Djibouti
Authors: Dugda Mulugeta T. , Nyblade Andrew A.
Published: September 2007

Crustal structure beneath the GEOSCOPE station ATD in Djibouti has been investigated using
H
-κ stacking of receiver functions and a joint inversion of receiver functions and surface wave group velocities. We obtain consistent results from the two methods. The crust is characterized by a Moho depth of 23 ± 1.5 km, a Poisson’s ratio of 0.31 ± 0.02, and a mean
V
p
of
c.
6.2 km s
−1
but
c.
6.9–7.0 km s
−1
below a 2–5 km-thick low-velocity layer at the surface. Some previous studies of crustal structure for Djibouti placed the Moho at 8 to 10 km depth, and we attribute this difference to how the Moho is defined (an increase of
V
p
to 7.4 km s
−1
in this study vs. 6.9 km s
−1
in previous studies). The crustal structure we obtained for ATD is similar to crustal structure in many other parts of central and eastern Afar. The high Poisson’s ratio and
V
p
throughout most of the crust indicate a mafic composition and are not consistent with models invoking crustal formation by stretching of pre-existing Precambrian crust. Instead, we suggest that the crust in Afar consists predominantly of new igneous rock emplaced during the late syn-rift stage where extension is accommodated within magmatic segments by dyking. Sill formation and underplating probably accompany the dyking to produce the new and largely mafic crust.
Crustal structure of the northern Main Ethiopian Rift from receiver function studies
Authors: Stuart G.W. , Bastow I.D. , Ebinger C.J.
Published: September 2007

The northern Main Ethiopian Rift captures the crustal response to the transition from continental rifting in the East African rift to the south, to incipient seafloor spreading in the Afar depression to the north. The region has also undergone plume-related uplift and flood basalt volcanism. Receiver functions from the EAGLE broadband network have been used to determine crustal thickness and average
V
p
/
V
s
for the northern Main Ethiopian Rift and its flanking plateaus.

On the flanks of the rift, the crust on the Somalian plate to the east is 38 to 40 km thick. On the western plateau, there is thicker crust to the NW (41–43 km) than to the SW (<40 km); the thinning taking place over an off-rift upper mantle low-velocity structure previously imaged by travel-time tomography. The crust is slightly more mafic (
V
p
/
V
s
∼ 1.85) on the western plateau on the Nubian Plate than on the Somalian Plate (
V
p
/
V
s
∼ 1.80). This could either be due to magmatic activity or different pre-rift crustal compositions. The Quaternary Butajira and Bishoftu volcanic chains, on the side of the rift, are characterized by thinned crust and a
V
p
/
V
s
> 2.0, indicative of partial melt within the crust.

Within the rift, the
V
p
/
V
s
ratio increases to greater than 2.0 (Poisson’s ratio, σ > 0.33) northwards towards the Afar depression. Such high values are indicative of partial melt in the crust and corroborate other geophysical evidence for increased magmatic activity as continental rifting evolves to oceanic spreading in Afar. Along the axis of the rift, crustal thickness varies from around 38 km in the south to 30 km in the north, with most of the change in Moho depth occurring just south of the Boset magmatic segment where the rift changes orientation. Segmentation of crustal structure both between the continental and transitional part of the rift and on the western plateau may be controlled by previous structural inheritances. Both the amount of crustal thinning and the mafic composition of the crust as shown by the observed
V
p
/
V
s
ratio suggest that the magma-assisted rifting hypothesis is an appropriate model for this transitional rift.
HIF-1 regulates hypoxia- and insulin-induced expression of apelin in adipocytes
Authors: Glassford Alexander J. , Yue Patrick , Sheikh Ahmad Y. , Chun Hyung J. , Zarafshar Shirin , Chan Denise A. , Reaven Gerald M. , Quertermous Thomas , Tsao Philip S.
Published: September 2007

Apelin, a novel peptide with significant cardioactive properties, is upregulated by insulin in adipocytes. However, the mechanism by which insulin promotes apelin production is unknown. Hypoxia-inducible factor-1 (HIF-1), a heterodimeric transcription factor involved in the angiogenic and metabolic responses to tissue hypoxia, has been shown to be activated by insulin in various settings. We therefore hypothesized that HIF-1 regulates insulin-mediated apelin expression in adipocytes. 3T3-L1 cells were differentiated into adipocytes in culture. For experiments, serum-starved 3T3-L1 cells were exposed to insulin and/or a 1% O2environment. Apelin expression was assessed using quantitative real-time PCR and ELISA. To directly assess the role of HIF-1 in apelin production, we differentiated mouse embryonic fibroblasts (MEFs) containing a targeted deletion of the HIF-1α gene into adipocytes and measured their response to insulin and hypoxia. Apelin expression in mature 3T3-L1 adipocytes was increased significantly by insulin and was attenuated by pharmacological inhibition of insulin signaling. Exposure of cells to either hypoxia or the chemical HIF activators cobalt chloride (CoCl2) and dimethyloxaloylglycine (DMOG) resulted in significant upregulation of apelin, consistent with a role for HIF in apelin induction. Moreover, hypoxia-, CoCl2-, DMOG-, and insulin-induced apelin expression were all attenuated in differentiated HIF-1α-deficient MEFs. In summary, in cultured 3T3-L1 adipocytes and differentiated MEFs, HIF-1 appears to be involved in hypoxia- and insulin-induced apelin expression.
Structural and functional interactions between FXYD5 and the Na+-K+-ATPase
Authors: Lubarski Irina , Karlish Steven J. D. , Garty Haim
Published: September 2007

FXYD5 is a member of a family of tissue-specific regulators of the Na+-K+-ATPase expressed in kidney tubules. Previously, we have shown that FXYD5 interacts with the αβ-subunits of the Na+-K+-ATPase and increases its Vmax (Lubarski I, Pihakaski-Maunsbach K, Karlish SJ, Maunsbach AB, Garty H. J Biol Chem 280: 37717–37724, 2005). The current study further characterizes structural interaction and structure-function relationships of FXYD5. FXYD5/FXYD4 chimeras expressed in Xenopus laevis oocytes have been used to demonstrate that both the high-affinity association with the pump and the increase in Vmax are mediated by the transmembrane domain of FXYD5. Several amino acids that participate in the high-affinity interaction between FXYD5 and the α-subunit of the Na+-K+-ATPase have been identified. The data suggest that different FXYD proteins interact similarly with the Na+-K+-ATPase and their transmembrane domains play a key role in both the structural interactions and functional effects. Other experiments have identified at least one splice variant of FXYD5 with 10 additional amino acids at the COOH terminus, suggesting the possibility of other functional effects not mediated by the transmembrane domain. FXYD5 could be specifically bound to wheat germ agglutinin beads, indicating that it is glycosylated. However, unlike previous findings in metastatic cells, such glycosylation does not evoke a large increase in the size of the protein expressed in native epithelia and X. laevis oocytes.
Nyctalopin Expression in Retinal Bipolar Cells Restores Visual Function in a Mouse Model of Complete X-Linked Congenital Stationary Night Blindness
Authors: Gregg Ronald G. , Kamermans Maarten , Klooster Jan , Lukasiewicz Peter D. , Peachey Neal S. , Vessey Kirstan A. , McCall Maureen A.
Published: September 2007

Mutations in the NYX gene that encodes the protein nyctalopin cause congenital stationary night blindness type 1. In no b-wave ( nob) mice, a mutation in Nyx results in a functional phenotype that includes the absence of the electroretinogram b-wave and abnormal spontaneous and light-evoked activity in retinal ganglion cells (RGCs). In contrast, there is no morphological abnormality in the retina at either the light or electron microscopic levels. These functional deficits suggest that nyctalopin is required for normal synaptic transmission between retinal photoreceptors and depolarizing bipolar cells (DBCs). However, the synaptic etiology and, specifically, the exact location and function of nyctalopin, remain uncertain. We show that nob DBCs fail to respond to exogenous application of the photoreceptor neurotransmitter, glutamate, thus demonstrating a postsynaptic deficit in photoreceptor to bipolar cell communication. To determine if postsynaptic expression of nyctalopin is necessary and sufficient to rescue the nob phenotype, we constructed transgenic mice that expressed an EYFP-nyctalopin fusion protein on the dendritic tips of the DBCs. Immunohistochemical and ultrastructural studies verified that fusion protein expression was limited to the DBC dendritic tips. Fusion gene expression in nob mice restored normal outer and inner visual function as determined by the electroretinogram and RGC spontaneous and evoked responses. Together, our data show that nyctalopin expression on DBC dendrites is required for normal function of the murine retina.
Magnetohydrodynamical Separation – Whatever Happened ?
Authors: Fletcher Derrick
Published: September 2007

Magnetohydrodynamical separation has been developed
in the eastern bloc with apparent success but has
largely been ignored by western science. Here a simple, theoretical
examination of the technique is undertaken and its potential
for particle separation is demonstrated to a degree
that poses the question – why has this technique not been fully
explored in the west?
Magnetizing Roast for Chalcopyrite: Effect of Particle Sizeand Dilution
Authors: Makarow Irina , Agrafiotis Thomas , Finch James A.
Published: September 2007

In excess oxvgen, 0‐37 μm CuFeS2 became magnetic
at a temperature of 280ºc. The magnetic product is copper
ferrite, CuO.Fe203. The ‘magnetizing’ temperature increased
with particle size apparently following the trend reported
for the ignition temperature. Dilution increased the magnetizing
temperature; 80% dilution by PbS, MoS2 or SiO2 increases
the temperature from 280ºC to over 420ºC. Sinterina
was a concurrent reaction. Nevertheless, a chalcopyrite/
galena mixture after roasting and gentle grinding was readily
separated on a Davis tube.
Magnetic Separator for Volatile Dust
Authors: Mendrela E. A. , Adamiak K. , Mendrela E. M.
Published: September 2007

The construction and principle of operation of a new
magnetic separator for volatile dust is described. The
results, obtained on a model separator in laboratory
conditions are discussed.
Magnetic Separation in Zambia
Authors: Agricola Jacobus N. M.
Published: September 2007

Magnetic separation facilities and research
activities in Zambia are described.
Influence of Polar Surface Forces on MagneticFlocculation of Fine Paramagnetic Minerals. I. Theory
Authors: Škvarla Jiří
Published: September 2007

A new surface‐thermodynamic conception of apolar and polar
interfaeial interactions, operating between hydrophilic and/or hydrophobic
mineral surfaces, was proposed for the van der Waals and polar (structural)
surface force components. Using this model, the interaction energy functions
calculated for two interacting paramagnetic model spheres showed that the
polar forces play a dominant role in magnetic flocculation.
Potential of a Dry Rotating‐Disk Magnetic Separator
Authors: Gerhold J.
Published: September 2007

Selectivity is a severe problem in dry magnetic separation. Dry
rotating‐disk magnetic separator utilizes radial magnetic forces that compete
against centrifugal mass forces. Genuine equilibrium of forces, which is
compulsory for high selectivity can thus be achieved at a high level of
magnetic force. The potential of an iron‐pole separator for intergrown
ferromagnetics, as well as of a superconducting system for paramagnetic
materials is discussed.
High‐Intensity Magnetic Separation of Limonite Iron Ores
Authors: Maliy V. M. , Bogdanova I. P.
Published: September 2007

Results of investigation into the development of HIMS technology
for separation of weakly magnetic finely disseminated limonite iron ores are
discussed.
Coal Desulphurisation and Ash Removal in Intensified Magnetic Fields
Authors: Saeid A. M. , Butcher D. A. , Rowson N. A.
Published: September 2007

Data is presented demonstrating the effect of high gradient/high
strength magnetic fields on a UK coal. Experimentation was carried out
using a high–intensity (HIW) magnetic separator and coarser coal fractions
were treated on a permanent magnetic roll separator capable of producing
exceptionally high magnetic field gradients.

Total sulphur and ash removal data is given for coal fractions after
magnetic treatment plus X–ray diffraction and magnetic profile analysis
provides identification of the mineral constitution of the ash fraction of the
coal.
Extraction of Ferromagnetic Particles by aSuspended Magnet
Authors: Svoboda J.
Published: September 2007

This paper investigates the mechanisms of extraction of
ferromagnetic bodies from a stream of bulk material by suspended magnets.
It is shown that the force density, usually used to evaluate a suspended
magnet, can give erroneous criteria for the magnet design and that the
magnetic field strength is the primary parameter in evaluating a suspended
magnet.
The Progress of the Magnetic Hydrocyclone
Authors: Freeman R. J. , Rowson N. A. , Veasey T. J. , Harris I. R.
Published: September 2007

A discussion is presented, describing the published designs of
magnetic of hydrocyclones and the outcome of using them to separate
magnetite–sand mixtures. The designs fall into two groups: first, where
magnetic–susceptible particles are attracted to the centre of the cyclone
and are discharged through the overflow and secondly, where particles are
attracted to the outer cyclone wall from where they exit via the underflow.
This report also covers theoretical assessments of magnetic hydrocyclones;
included is a modelling study, detailing how the resultant force experienced
by the particles would vary with the number of magnetic poles incorporated
in the hydrocyclone design. At the end of the paper, a new project is
introduced, based on the conclusions of the above studies. This will use
powerful rare–earth–type permanent magnets to provide high field values
and gradients. With this approach it is hoped to overcome the difficulties
encountered with previous designs.
Kaolin Beneficiation in a High–Gradient Magnetic Separator With a Ball Matrix
Authors: Sultanovich E. A. , Karmazin V. I.
Published: September 2007

Results are given of investigations into the determination of the
main structural and technological parameters of a high–gradient magnetic
separator with a ball matrix. The design has been developed and a
possibility has been outlined of effective beneficiation of kaolin at the
magnetic induction 1.0 to 1.2 T. Comparative tests of separators with a ball
matrix and a steel wool matrix (SALA–HGMS) have shown that the
parameters of separation are the same. In the former case, however, a
considerable reduction in specific input of metal, electrical energy, water
and air per tonne of product is achieved. The advantage of the ball matrix
is most fully displayed at the extraction of finely dispersed weakly magnetic
particles from ores and slimes of low content of magnetic fraction.
Separation of Particles in the Corona–Discharge Field
Authors: Svoboda J.
Published: September 2007

A model of particle behaviour under the influence of corona
discharge is developed and the effect of particle conductivity on the
separation process is outlined. The model can be used to calculate the
minimum difference in conductivities of particles to be separated, as a
function of particle size. The critical angular velocity of the rotor, the
limiting particle size and the angle of separation can be derived.
New Magnetic Filter for Chemical Industry
Authors: Spevakova I. , Ruditser L. , Eroshenko V. , Nickolskiy G.
Published: September 2007

An economical, inexpensive and compact magnetic filter with
pulse magnetization and demagnetization of the filtering matrix, consuming
no electric power throughout the process was constructed and its
effectiveness was tested with micron–sized magnetite and Raney nickel
catalyst. Complete filtration of + 1 μm particles was achieved at rate ≤
150 m/h. The proposed filter can be of use in chemical industry for the
recovery of micron–sized magnetic particles from various liquors.
Physical Interpretation of The Separation Criteria
Authors: Lin I. J. , Katyshev A.
Published: September 2007

This work considers a separation process and the attendant losses
on the basis of thermodynamic analogies. Energy—oriented efficiency as a
criterion of the process, and the entropy—oriented efficiency as a criterion
of its results, are compared. An example shows that the values are close to
each other. As a practical recommendation, a modification of the feeder
system is suggested.
The Distribution of Magnetic Susceptibility in Crushed Ores
Authors: Broźek Marian
Published: September 2007

Particles of the crushed products form a dispersive system in
which the continuous phase (waste rock) constitutes a matrix for inclusions
of dispersed phases (metal–bearing minerals). In the process of crushing
multicomponent ores, the inclusions of dispersed phases are bound in
random to the consecutive particles of the crushed product. Value of of the
magnetic susceptibility of particles depends on the number of inclusions of
magnetic minerals. Starting from the assumption that the number of
inclusions in the particles of narrow size fraction has the Poisson
distribution, the author has derived an equation of the distribution function
of the magnetic susceptibility of particles of narrow size fraction. The
distribution function is expressed by the Pearson function. This paper
presents a detailed form of this function for weakly and strongly magnetic
ores. Parameters of the distribution function are connected to the values
characterising a given sample.
Electrostatic Separation of Pyrite From Coal
Authors: Butcher D. A. , Rowson N. A.
Published: September 2007

This paper reviews the various forms of electrostatic separation
available to remove sulphur, in the form of pyrite (FeS2) from coal.
Research has been carried out to desulphurise coal using an electrostatic
roll separator which uses the corona charging technique. Data is presented
here to conflict with previous reports that indicated that the electrostatic
roll separator is unable to separate pyrite from coal. Separation was
undertaken under various atmospheric conditions, with various feed
pretreatments.
Electrostatic Shape Separation of Flake Mica From Pegmatites
Authors: Yuga Al. , Dascalescu L. , Morar R. , Samuila A. , Cuglesan I.
Published: September 2007

Electrostatic shape separation was considered to be an adequate
technique for processing a particulate mixture of flake mica and isometric
granules of feldspar and quartz. The authors carried out extensive
laboratory experiments to concentrate flake muscovite from a pegmatitic
product with content of 50 to 65% of mica. Prior to electroseparation, the
granular material was dried and vibrating screens were employed to obtain
two fractions: +1 mm (which represented more than 70% of the feed), and
–1 + 0.315 mm. Each fraction was then treated in the corona–field
roll–type separator. In the first group of experiments, two corona electrodes
of opposite polarities were conveniently located relative to the grounded
metallic roll carrier. The second group of experiments necessitated one
corona electrode only, but the roll carrier was covered by a dielectric layer.
These two electrostatic shape separation methods were discussed, based on
a crude evaluation of the charges and forces which act on various
constituents of the granular mixture. Mica concentrates with 45.47% SiO2,
36.08% Al2O3 and 10.4% (K2O + Na2O) were obtained, using a two–stage
electroseparation scheme. These products fulfill the requirements regarding
the composition and the size distribution of the flake mica for several
applications in the industry of electrical insulating materials.
Simultaneous Hydrophobic and Magnetic Flocculation of Fine Paramagnetic Mineral Particles inAqueous Suspension
Authors: Song Shaoxian , Lu Shouci
Published: September 2007

Flocculation of fine paramagnetic particles rendered hydrophobic by absorption of
surfactants in external magnetic field in aqueous suspension, called simultaneous
hydrophobic and magnetic flocculation (SHMF), has been studied through a
theoretical approach and experiments. All interactions between fine paramagnetic
particles in the case of SHMF are being discussed in this paper. Through extension
of the classical DLVO theory, the theory of stability of fine particles in aqueous
suspension in the case of SHMF is proposed. Potential energies of interaction
between fine rhodochrosite particles rendered hydrophobic by absorption of sodium
oleate in external magnetic field have been calculated from the theory.
Experimental results of SHMF of fine rhodochrosite and siderite particles showed
that SHMF exhibits much stronger and faster aggregation then either hydrophobic
or magnetic flocculation alone. Two examples of SHMF applied to fine particle
processing are given.
The Application of Heterogeneous PolarisableFluids in Mineral Processing
Authors: Lovás Michal , Jakabský Štefan , Hredzák Slavomír
Published: September 2007

The paper deals with the application of ferrofluids in mineral
processing. The efficiency of primary and secondary raw material separation
by the magnetohydrostatic method is dependent on convenient distribution
and on the stabilisation of density of the ferrofluid. To determine this
density, the effective dynamometric method based on measurement of the
buoyant force was constructed. A density controller has been developed for
stabilisation and control of the density. Influence of some factors on the
separation process, as well as the results of magnetohydrostatic separation
are described.
Upgrading of Raw Perlite by a DryMagnetic Technique
Authors: Herskovitch D. , Lin I. J.
Published: September 2007

Perlite of composition SiO2 73.6%, Al2O3 12.4%, Fe2O3 1.25%, MgO 0.15%, Na2O
2.99%, K2O 4.18%, H2O+ 3.17%, H2O- 0.2%, and found to contain 89.4% of
amorphous phase and 10.6% of crystalline phase, the latter consisting of feldspars,
biotite, quartz, magnetite and chlorite, was studied. Due to its largely amorphous
nature, chemical composition and melting behaviour, perlite can be used in the
manufacture of ceramics. For the glass industry, on the other hand, an
impediment, albeit the only one, is the iron content, so that the iron—bearing
minerals must be removed, which can be accomplished by dry magnetic separation.
Laboratory and pilot—plant separation experiments carried out with these minerals
showed that the Fe2O3 content cannot be reduced to below 0.65% owing to small
inclusions of iron—bearing minerals that remain in the other minerals, or in the
amorphous particles. Perlite with an Fe2O3 content below 0.7% and grain size of
less than 1 mm can, however, be used in the production of coloured glass
containers.
Charging Mechanisms for Particles Prior to Electrostatic Separation
Authors: Lindley K. S. , Rowson N. A.
Published: September 2007

The four principal methods available for charging particles prior to
electrostatic separation are by grinding, triboelectrification, corona charging
and charging by induction. Each of these mechanisms gives rise to surface
charge and are discussed in this paper. Each is a distinct mechanism but in
most practical separation processes two or more will occur.
Contribution of Cryomagnetismto Separation of Non‐Ferrous Metals From Waste Products
Authors: Gillet G. , Diot F. , Védrine H.
Published: September 2007

The authors have studied the use of the cryomagnetic separation techniques for the processing
of non‐ferrous waste since 1989. This paper presents:
– the superconducting magnetic separator and the adapted processing installation;
– the main results achieved by tests with synthetic and industrial effluents containing
Ni, Cr, Zn, Cu or V.
The research work confirmed the assumption that a cryomagnetic separation can be
applied to non‐ferrous waste materials. Technical difficulties of implementing this technique
are understood. A patent containing the innovative process seems to be ofcommon
interest for the processing of fluids charged with small amounts of dissolved metals.
As a result of the investigations such an installation appears to be a new way to extract
metals from fluids before they are discharged into nature. This is important in view ofmore
stringent controls in the future.