scholarly journals Ti3+ in corundum traces crystal growth in a highly reduced magma

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Beñat Oliveira ◽  
William L. Griffin ◽  
Sarah E. M. Gain ◽  
Martin Saunders ◽  
Jeremy Shaw ◽  
...  
Keyword(s):  
Closed System ◽  
Incompatible Element ◽  
Explosive Eruption ◽  
Linear Increase ◽  
Corundum Structure ◽  
Exponential Increase ◽  
Tectonic Settings ◽  
The Individual ◽  
Growth Zoning ◽  
Melt Pockets

AbstractAggregates of corundum crystals with skeletal to hopper morphology occur in pyroclastic rocks erupted from Cretaceous basaltic volcanoes on Mt Carmel, N. Israel. The rapid growth of the crystals trapped volumes of the parental Al2O3-supersaturated melt; phenocrysts of tistarite (Ti2O3) in the trapped melts indicate crystallization at oxygen fugacities 6–7 log units below the Iron-Wüstite buffer (fO2 = ΔIW − 6 to − 7), induced by fluxes of mantle-derived CH4-H2 fluids. Cathodoluminescence images reveal growth zoning within the individual crystals of the aggregates, related to the substitution of Ti3+ in the corundum structure. Ti contents are < 0.3 wt% initially, then increase first linearly, then exponentially, toward adjacent melt pockets to reach values > 2 wt%. Numerical modelling indicates that the first skeletal crystals grew in an open system, from a moving magma. The subsequent linear increase in Ti reflects growth in a partially closed system, with decreasing porosity; the exponential increase in Ti close to melt pockets reflects closed-system growth, leading to dramatic increases in incompatible-element concentrations in the residual melts. We suggest that the corundum aggregates grew in melt/fluid conduits; diffusion modelling implies timescales of days to years before crystallization was terminated by explosive eruption. These processes probably operate in explosive volcanic systems in several tectonic settings.

Temporal Changes in the Suburban Avifauna of an Inland City

1981 ◽  
Vol 8 (1) ◽  
pp. 109 ◽  
Author(s):  
DN Jones
Keyword(s):  
Species Diversity ◽  
Population Density ◽  
Native Species ◽  
Bird Community ◽  
Linear Increase ◽  
Residential Area ◽  
Wagga Wagga ◽  
Residential Areas ◽  
House Sparrows ◽  
The Individual

The suburban bird community of Wagga Wagga, N.S.W., was surveyed during December 1978-January 1979 and May 1979, at nine sites selected to cover all ages of residential areas from predevelopment to oldest suburbs and to demonstrate how the bird community will change with time in response to changing habitat. Non-residential sites were also sampled. Sites were censused by foot transect. House sparrows which were present in all sites, were the first species to colonize new residential areas and made up over 95% of the individual count of four sites Of native species, 40% were found in undeveloped sites only. The population density of undeveloped sites was only half that of developed sites, but the greatest species diversity was found in undeveloped sites and the lowest in the most altered sites. There was strong evidence for a steady linear increase in numbers of individuals, numbers of species, biomass and population density with increasing age of residential area, reaching a peak at about 30 years.

A Comprehensive Review of the Worldwide Existing Tsunami Databases

2020 ◽  
Vol 14 (05) ◽  
pp. 2040003
Author(s):  
Sixue Cheng ◽  
Jun Zeng ◽  
Haijiang Liu
Keyword(s):  
Data Storage ◽  
Tsunami Wave ◽  
Structural Features ◽  
General Information ◽  
Linear Increase ◽  
Relevant Research ◽  
Comprehensive Review ◽  
Significant Research ◽  
Wave Heights ◽  
The Individual

Tsunami databases contain general information of historical tsunamis, which provides valuable and fundamental data to tsunami-related researches. Nevertheless, before adopting the information stored in various tsunami databases, users should be familiar with these databases’ individual features due to their inhomogeneity in data storage. To this end, a comprehensive review of the worldwide existing tsunami databases was conducted in this study. Two kinds of existing databases are recognized, i.e. the individual database and the organizational database. The individual tsunami databases are generally simple and descriptive with less information about tsunami and associated earthquake. Update of individual database is also out of date. Nevertheless, the organizational tsunami databases, with the retrieval function and timely update, are more sophisticated with significant research orientated information, upon which we can obtain the detailed characteristics of a specified tsunami event. In addition, a further comparison is made between two main organizational databases, i.e. the databases of NTL/WLD and NGDC/WDS. In which, the number of recorded tsunami wave heights per event and the number of definite tsunami events per decade both witness an apparent increase after 1900s, and the landslide-generated tsunamis are found to gradually increase after 1960s. The total tsunami events per decade fluctuate around one hundred since 1990s, whereas the definite tsunami events per decade experience a linear increase in this period. It turns out that though quite a part of the data in NTL/WLD is referred to NGDC/WDS, they do collect different tsunami events, and even for the same event, their recording datasets are still not consistent with each other. Figuring out the structural features of different databases and unveiling their connections and differences facilitate relevant research for disaster prevention and mitigation.

scholarly journals Comparison of modern high-speed vitrectomy systems and the advantages of using dual-bladed probes

2021 ◽  
Vol 7 (1) ◽  
Author(s):  
R. Oravecz ◽  
D. Uthoff ◽  
N. Schrage ◽  
R. M. Dutescu
Keyword(s):  
High Speed ◽  
Vision System ◽  
Area Under The Curve ◽  
Egg White ◽  
Linear Increase ◽  
Video Recordings ◽  
Vitreous Traction ◽  
Reverse Relationship ◽  
The Individual ◽  
Vitrectomy System

Abstract Purpose This study analyzes the efficiency of different vitrectomy systems and compares single with double-bladed cutters. Methods The systems EVA™ (DORC), Constellation® Vision System (ALCON), megaTRON S4HPS (Geuder) and Stellaris® PC (Bausch and Lomb) were used. We chose 20G and 23G probes, since not all systems had switched to a smaller G at the time the study was conducted in 2016. Cut rates were varied in increments of 1000 cuts/min from 500 cpm to the system’s maximum and vacuum pressures were varied in increments of 100 mmHg, from 100 to 600 mmHg up to the individual system’s maximum. In this study water, egg white, Pluronic®−F127 gel and isolated porcine vitreous were used as models of human vitreous. The vitrectomy efficiency was calculated from the aspirated mass (g) within 30 s. The aperture of the different vitrectomy probes was filmed with a high-speed camera. Results The area under the curve analysis showed differences in efficiency between vitrectomy systems. For water, a reverse relationship between the aspirated mass and cut rate was shown. By contrast, for most systems aspirated egg white and porcine vitreous showed a non-linear increase or decrease for 4000 cpm and above. For all vitreous surrogates, EVA™’s double-bladed probe aspirated significantly (p < 0.001) more vitreous than its mono-bladed probe. Video recordings showed less vitreous traction for double- in contrast to single-bladed probes. Conclusion We can demonstrate differences in the efficiency of vitrectomy depending on the vitrectomy system used. Double-bladed probes were more efficient and probably safer than single-bladed probes.

scholarly journals Integrated Approach to Investigate the Effect of Leachate on Groundwater around the Ikot Ekpene Dumpsite in Akwa Ibom State, Southeastern Nigeria

2014 ◽  
Vol 2014 ◽  
pp. 1-12 ◽  
Author(s):  
N. J. George ◽  
A. I. Ubom ◽  
J. I. Ibanga
Keyword(s):  
Cross Sections ◽  
Ion Pairs ◽  
Integrated Approach ◽  
Southeastern Nigeria ◽  
Exponential Increase ◽  
Southern Nigeria ◽  
Subsurface Layers ◽  
The Individual ◽  
Depth Of Burial ◽  
Water Resistivity

Geophysical, geochemical, and hydrogeological measurements have been integrated to assess the effect of leachate on groundwater quality within the dumpsite in Ikot Epene Local Government Area of Akwa Ibom State, Southern Nigeria, and its environs. The resistivity values and depth of burial of the geomaterials, constrained by geology, were used in producing resistivity cross sections which show the geoelectric distribution of the subsurface near and away from the dumpsite. The observed high conductivity in subsurface layers closed to the dumpsite is symptomatic of the leachate-loaded conductive fluid leached and drained into the subsurface. The hydrochemical results of some species conform to WHO standards, while some were found to be relatively higher due to dissolution, leaching, and draining of leachate related contaminants in the soil. The correlation indices of the ion pairs show no significant effect on the paired ions, indicating that the significant value of some of the individual ions is not geologic but due to precipitation from the leachate residue. In general, the effect of leachate is more dominant in the immediate groundwater pathway near the dumpsite than aquifer repositories away from it. The crossplots of the water resistivity and bulk resistivity show exponential increase for the different layers.

scholarly journals Twisting of Fibers Balancing the Gel–Sol Transition in Cellulose Aqueous Suspensions

Polymers ◽  
2019 ◽  
Vol 11 (5) ◽  
pp. 873 ◽  
Author(s):  
Dmitry Zlenko ◽  
Sergey Nikolsky ◽  
Alexander Vedenkin ◽  
Galina Politenkova ◽  
Aleksey Skoblin ◽  
...  
Keyword(s):  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Cellulose Fibers ◽  
Film Production ◽  
3D Scaffold ◽  
Friction Forces ◽  
Practical Applications ◽  
Exponential Increase ◽  
The Individual ◽  
Scanning Electron

Cellulose hydrogels and films are advantageous materials that are applied in modern industry and medicine. Cellulose hydrogels have a stable scaffold and never form films upon drying, while viscous cellulose hydrosols are liquids that could be used for film production. So, stabilizing either a gel or sol state in cellulose suspensions is a worthwhile challenge, significant for the practical applications. However, there is no theory describing the cellulose fibers’ behavior and processes underlying cellulose-gel-scaffold stabilizing. In this work, we provide a phenomenological mechanism explaining the transition between the stable-gel and shapeless-sol states in a cellulose suspension. We suppose that cellulose macromolecules and nanofibrils under strong dispersing treatment (such as sonication) partially untwist and dissociate, and then reassemble in a 3D scaffold having the individual elements twisted in the nodes. The latter leads to an exponential increase in friction forces between the fibers and to the corresponding fastening of the scaffold. We confirm our theory by the data on the circular dichroism of the cellulose suspensions, as well as by the direct scanning electron microscope (SEM) observations and theoretical assessments.

scholarly journals Chemical signature of two Permian volcanic ash deposits within a bentonite bed from Melo, Uruguay

2006 ◽  
Vol 78 (3) ◽  
pp. 525-541 ◽  
Author(s):  
Liane M. Calarge ◽  
Alain Meunier ◽  
Bruno Lanson ◽  
Milton L.L. Formoso
Keyword(s):  
Ethylene Glycol ◽  
Closed System ◽  
Volcanic Ash ◽  
Incompatible Element ◽  
Volcanic Glass ◽  
Minor Element ◽  
Element Abundances ◽  
Clay Deposit ◽  
Lagoonal Water ◽  
Early Alteration

A Permian bentonite deposit at Melo, Uruguay is composed of a calcite-cemented sandstone containing clay pseudomorphs of glass shards (0-0.50 m) overlying a pink massive clay deposit (0.50-2.10m). The massive bed is composed of two layers containing quartz and smectite or pure smectite respectively. The smectite is remarkably homogeneous throughout the profile: it is a complex mixed layer composed of three layer types whose expandability with ethylene glycol (2EG 1EG or 0EG sheets in the interlayer zone which correspond to low-, medium- and high-charge layers respectively) varies with the cation saturating the interlayer zone. The smectite homogeneity through the profile is the signature of an early alteration process in a lagoonal water which was over saturated with respect to calcite. Compaction during burial has made the bentonite bed a K-depleted closed system in which diagenetic illitization was inhibited. Variations in major, REE and minor element abundances throughout the massive clay deposit suggest that it originated from two successive ash falls. The incompatible element abundances are consistent with that of a volcanic glass fractionated from a rhyolite magma formed in a subduction/collision geological context.

Retrospective-geographical analysis of the formation and change of the state of ponds of the Volyn Region in the XIX-XXI centuries

2019 ◽  
Vol 96 (4-6) ◽  
pp. 7-20
Author(s):  
Ivan Grytsiuk ◽  
Eugen Ivanov ◽  
Ivan Kovalchuk
Keyword(s):  
Rural Areas ◽  
Linear Increase ◽  
Agricultural Products ◽  
Historical Period ◽  
Average Area ◽  
Exponential Increase ◽  
Recreation Areas ◽  
Xix Century ◽  
Post Industrial ◽  
Historical Periods

The main retrospective-geographical (historical) stages of ponds formation in the Volyn Region are considered – initial, early (manufactory), industrial and modern (agrarian, post-industrial). In order to analyse conditions and functioning of the region’s pond farms we used topographic maps for four historical periods: Commonwealth of Poland historical atlas (scale 1 : 300,000, early ХІХ century), Russian Empire (scale 1 : 126,000, 1875), Polish (scale 1 : 100,000, 1924-1933) and Soviet maps (scale 1 : 100,000, 1977-1992). They reflect the trend of changes in the parameters and functioning of the existing ponds in the Volyn Region over the last 220 years. Landscape-hydrological systems were selected for geospatial analysis of location features of the ponds and water mills within the Volyn Region. Overall, 19 individual landscape-hydrological systems were established. An exponential increase in the number of ponds in early and industrial stages was identified, considering some decreases in particular historical periods. The number of ponds in the region varied from 76 (in the 1970s) to 625 units (1970-80s). A clear, almost linear, increase in ponds total area was observed. During the studied historical period, the area of ponds increased from 1,553.7 to 4,242.4 ha. The highest concentration of pond farms is specific to the landscape-hydrological systems of the Volyn Highland, especially to the Stir-III sub-basins (29.9 % of the total count in the region), Luga-III and Goryn-III. At the same time, a gradual decrease in the average area of a pond – from 20.44 (in the 70s of the XIX century) to 6.28 ha (70-80 years of the XX century) was shown. The considerable number of ponds in the rural areas of the Volyn Region is an important factor in the creation of new work places, recreation areas, diversification of agricultural products and feed base.

Ensembles of the Lorenz attractor

1993 ◽  
Vol 441 (1912) ◽  
pp. 291-312 ◽  
Keyword(s):  
Closed System ◽  
Temporal Evolution ◽  
Initial Conditions ◽  
Lorenz Attractor ◽  
Present Formulation ◽  
Lorenz Equations ◽  
Averaged Equations ◽  
Sensitive Dependence ◽  
Large Ensembles ◽  
The Individual

The temporal evolution of small and large ensembles is examined for the Lorenz equations. It is shown that a general closed system of ensemble averaged equations can be developed for the Lorenz equations, independent of the size of the ensemble. The closure is based on the method of Rothmayer & Black (1993). The present formulation gives a deterministic set of equations for the description of ensembles of the Lorenz attractor. Large ensemble solutions of the strange attractor computed in this study are found to be regular, without the sensitive dependence on initial conditions which characterizes the individual chaotic members of the ensemble.

scholarly journals Analysis on the Interference Assembly of Camshaft With Knurled Tube and Cam

2021 ◽  
Author(s):  
Xiaoming Huang ◽  
Weitao Sun ◽  
Xiaoliang Liu ◽  
Yucan Wang ◽  
Jin Xing ◽  
...  
Keyword(s):  
Elastic Limit ◽  
Linear Increase ◽  
Thick Wall ◽  
Metal Line ◽  
Exponential Increase ◽  
Cylinder Model ◽  
Metallographic Observation ◽  
Torque Capacity ◽  
The Relationship ◽  
Joining Process

Abstract Interference joint is one of the most advanced assembly methods for camshaft. In this paper, the mechanism of camshaft interference assembly is analyzed by thick-wall cylinder model. Joining/tortion experiments are done to estimate the joining force and connection strength. The relationship between the torque capacity, joining force and interference of the camshaft is established by the experiment results. Joining force linear increase with the interference, and torque exponential increase with it. The plastic deformation characteristics of knurled teeth on the tube during the joining process are obtained by metallographic observation. The results reveal the metal line changes continuously of the knurled tube. The knurled tooth tip turns over after joining. And elastic limit would be reached in the extrusion region.

Developmental trajectories in infant pointing: The effects of vocalisation and communicative intention

2020 ◽  
pp. 014272372098019
Author(s):  
Paola Perucchini ◽  
Arianna Bello ◽  
Fabio Presaghi ◽  
Tiziana Aureli
Keyword(s):  
Longitudinal Study ◽  
Individual Differences ◽  
Multilevel Analysis ◽  
Random Effects ◽  
Developmental Trajectories ◽  
Linear Increase ◽  
Communicative Intention ◽  
Quadratic Component ◽  
Age Trends ◽  
The Individual

The goal of this intensive longitudinal study was to trace the developmental trajectories of infant pointing production, through consideration of the modality (i.e. pointing alone vs pointing–vocal coupling) and the communicative intention (i.e. imperative vs declarative). Multilevel analysis was used to model the normative trend and the individual differences in pointing trajectories. Eighteen Italian infants participated in this study and were followed monthly from 9 to 18 months of age. The infants were involved in a structured task designed to elicit imperative and declarative pointing (T-POINT). The proportion of pointing for each participant as a function of age, modality (pointing alone vs pointing–vocal coupling) and context (imperative vs declarative), and the interactional effects, were modelled. Random effects among participants for age trends were estimated. This analysis defined the following: (1) a significant linear increase in pointing production, without and with vocalisation; (2) a significant increase in pointing–vocal coupling over pointing produced alone, in an accelerated form; (3) that the context does not appear to moderate linear and quadratic trends; and (4) that infants differed in their developmental trajectories with respect to the quadratic component, which means that some of the infants developed faster with age than the others. Results are discussed with respect to the hypothesis of strong integration between different systems of communication, further underlining the progression of pointing–vocal coupling.

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