[Ba x Cs y ][(Ti, Al) 3+ 2 x + y Ti 4+ 8-2 x - y ]O 16 Synroc-type hollandites I. Phase chemistry

1986 ◽  
Vol 405 (1828) ◽  
pp. 73-101 ◽  
Keyword(s):  
Three Dimensional ◽  
Site Occupancy ◽  
Minor Effect ◽  
Phase Assemblage ◽  
Formula Unit ◽  
Two Component ◽  
High Level ◽  
A Minor ◽  
End Members ◽  
Phase Chemistry

A series of [Ba x Cs y ][(Ti, Al) 3+ 2 x + y Ti 4+ 8-2 x - y ]O 16 hollandites, synthesized at 1250°C and coexisting with ‘reduced ’ rutile, demonstrates complete solid solution between barium and caesium endmembers, and simultaneously between Ti 3+ and Al 3+ . The presence or absence of rutile has only a minor effect on stoichiometry. For barium endmember hollandites ( y = 0) the stoichiometry (i. e. tunnel site occupancy) ranges from 1.08 ≼ x ≼ 1.14, whilst for caesium endmember hollandites ( x = 0) 1.32 ≼ y ≼ 1.51. Neither x nor y correlates with the nature and proportions of trivalent species. An appropriate stoichiometry for the aluminous barium end-member is confirmed as Ba 1.14 Al 2.29 Ti 5.71 O 16 . The composition BaO. Al 2 O 3 . 5TiO 2 yields this same hoilandite, and not the supposed phase ‘BaAl 2 Ti 5 O 14 ’. The phase ‘BaAl 2 Ti 4 O 12 ’ does not exist, while the composition BaO. Al 2 O 3 . 4TiO 2 crystallizes to an assemblage containing the hollandite mentioned above. Reinterpretation of published X-ray diffraction data substantiate these conclusions and are consistent with a 5 c supercell for hollandite. Superlattice ordering in [Ba x Cs y ][(Ti, Al) 3+ 2 x + y Ti 4+ 8-2 x - y ]O 16 hollandites may be commensurate or incommensurate, with typical multiplicity values ( m ) and tunnel-site occupancies ( x + y ) correlating with increasing caesium content per formula unit throughout the series. Barium end-members and barium-rich hollandites, with Cs + ≼ 0.33 and tunnel-site occupancies of 1.03‒1.15 display 4.5 ≼ m ≼ 5.0. Intermediate hollandites with 0.40 ≼ Cs + ≼ 0.70 and tunnel-site occupancies ranging from 1.14 to 1.23 possess superstructures with 5.5 ≼ m ≼ 5.7, whereas caesium endmembers and caesium-rich hollandites have tunnel-site occupancies between 1.12 and 1.51 and 5.9 ≼ m ≼ 6.3. For barium or caesium endmembers, multiplicities fail to correlate with tunnel-site occupancies, but do increase with increasing percentages of molar Al 3+ /(Al 3+ + Ti 3+ ) in the structure. Superlattice periodicity is considerably more sensitive to changes in the barium‒caesium content of tunnel sites than to variation in the nature of the trivalent species. Long-range superlattice order is determined not so much by the tunnel cations as by the trivalent species. With more than about one Al 3+ per formula unit, one-dimensional (uncorrelated) ordering is suppressed, and three-dimensional order occurs almost exclusively. Hollandite superstructures, and thus their stoichio­metries, are determined both by mutual repulsion between large cations within individual tunnels, and intertunnel interaction between large cations. The ceramic high-level nuclear wasteform, Synroc, contains a titanate hollandite belonging to the above series. It has been suggested that the capacity of Synroc to immobilize caesium may be impaired if caesium and barium are not incorporated solely in hollandite, but are partitioned between hollandite and additional titanate phases or hollandite-related structures. No such phase has been encountered in the synthesis of the above hollandite series or in Synroc, prepared according to current specifications, because the trivalent species are present in sufficient abundance to allow the incorporation of all barium and caesium in hollandite. Consequently two-component titanates (for example Cs 2 Ti 6 O 13 or Ba 2 Ti 9 O 20 ), do not appear in the phase assemblage. Moreover, the trivalent species do not comprise Al 3+ alone but also include some Ti 3+ , which promotes more favourable structural modifications and kinetics. Furthermore, the phase assemblage includes ‘reduced’ rutile, which effectively prohibits crystallization of two-component titanates with [Ba, Cs]/[Ti] ratios higher than that in hollandite, and also three-component [Ba, Cs] [Ti, Al] 3+ -titanates other than hollandite. When these three criteria are satisfied, the appearance of additional, potentially undesirable phases in the Synroc mineralogy is suppressed, and all barium, caesium (and rubidium) may be successfully immobilized in hollandite.

scholarly journals Crystal structure of poly[[di-μ3-acetato-tetraaquabis(μ2-cyclohexane-1,4-dicarboxylato)dilanthanum(III)] dihydrate]

2017 ◽  
Vol 73 (12) ◽  
pp. 1926-1930
Author(s):  
R. Drisya ◽  
U. S. Soumya Mol ◽  
P. R. Satheesh Chandran ◽  
M. Sithambaresan ◽  
M. R. Sudarsankumar
Keyword(s):  
Crystal Structure ◽  
Coordination Mode ◽  
Three Dimensional ◽  
Raw Material ◽  
Water Molecules ◽  
Supramolecular Network ◽  
Formula Unit ◽  
Remarkable Feature ◽  
Two Component ◽  
Coordinated Water

The title compound, {[La2(CH3COO)2(C8H10O4)2(H2O)4]·2H2O}nor [La2(ac)2(e,a-cis-1,4-chdc)2(H2O)4]·2H2O, whereacis acetate and 1,4-chdc is cyclohexane-1,4-dicarboxylate anion, is a binuclear lanthanum(III) complex. Each metal atom is decacoordinated by four O atoms from two distinct 1,4-chdc2−ligands, four O atoms from three acetate groups and two O atoms from coordinated water molecules to form a distorted bicapped square-antiprismatic geometry. Two non-coordinated water molecules are also present in the formula unit. The most remarkable feature of this compound is that it possesses a onlycisconformation for cyclohexane-1,4-dicarboxylic acid, although the raw material consists of a mixture ofcisandtransisomers. The μ3-η2:η2coordination mode of the bridging acetate group and the flexible dicarboxylate fragments of 1,4-chdc2−results in the formation of infinite two-dimensional lanthanide–carboxylate layers within the crystal structure. The directionality of strong intermolecular O—H...O and weak C—H...O interactions provides robustness to the layers, which leads to the construction of a three-dimensional supramolecular network. The crystal studied was refined as a two-component twin.

Influence of patch length and thickness on strength and stiffness of patched laminates

2017 ◽  
Vol 52 (16) ◽  
pp. 2199-2212 ◽  
Author(s):  
Bernhard Horn ◽  
Johannes Neumayer ◽  
Klaus Drechsler
Keyword(s):  
Tensile Strength ◽  
Composite Laminates ◽  
Three Dimensional ◽  
Minor Effect ◽  
Stiffness Properties ◽  
Additional Testing ◽  
Strength And Stiffness ◽  
Cohesive Zone Elements ◽  
A Minor ◽  
Patch Length

Composite laminates made of fiber patches offer a large flexibility in terms of layup design. Geometrical layup parameters such as patch length and patch thickness are unique for this type of laminates. This article presents results on the investigation of the influence of patch length and patch thickness on the tensile strength and stiffness properties of patched laminates to contribute to the material understanding. The results show that an increasing of patch thickness leads to a drastic reduction in tensile strength of up to 48.7% for a triplication in patch thickness. The patch length was varied between 20 and 120 mm. Up to 60 mm, the tensile strength increased by 11.5%, further increase did not contribute to a further improved tensile strength. The influence of patch length and patch thickness on the stiffness was found to have only a minor effect. A three-dimensional numerical model that accounts for delamination failure using cohesive zone elements shows very good correlation with the experimental results. This shows its potential for virtual testing to determine tensile strength and stiffness properties of patched laminates without additional testing effort.

scholarly journals A Three-Dimensional Parametric Biomechanical Rider Model for Multibody Applications

2020 ◽  
Vol 10 (13) ◽  
pp. 4509
Author(s):  
Matteo Bova ◽  
Matteo Massaro ◽  
Nicola Petrone
Keyword(s):  
Center Of Mass ◽  
Three Dimensional ◽  
The Body ◽  
Experimental Comparison ◽  
Minor Effect ◽  
Data Sets ◽  
Data Set ◽  
Multibody Model ◽  
Inertial Parameters ◽  
A Minor

Bicycles and motorcycles are characterized by large rider-to-vehicle mass ratios, thus making estimation of the rider’s inertia especially relevant. The total inertia can be derived from the body segment inertial properties (BSIP) which, in turn, can be obtained from the prediction/regression formulas available in the literature. Therefore, a parametric multibody three-dimensional rider model is devised, where the four most-used BSIP formulas (herein named Dempster, Reynolds-NASA, Zatsiorsky–DeLeva, and McConville–Young–Dumas, after their authors) are implemented. After an experimental comparison, the effects of the main posture parameters (i.e., torso inclination, knee distance, elbow distance, and rider height) are analyzed in three riding conditions (sport, touring, and scooter). It is found that the elbow distance has a minor effect on the location of the center of mass and moments of inertia, while the effect of the knee distance is on the same order magnitude as changing the BSIP data set. Torso inclination and rider height are the most relevant parameters. Tables with the coefficients necessary to populate the three-dimensional rider model with the four data sets considered are given. Typical inertial parameters of the whole rider are also given, as a reference for those not willing to implement the full multibody model.

scholarly journals Inclusion Behavior in a Curved Bloom Continuous Caster with Mold Electromagnetic Stirring

Metals ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 1580
Author(s):  
Weixian Wang ◽  
Shifu Chen ◽  
Hong Lei ◽  
Hongwei Zhang ◽  
Hongjin Xiong ◽  
...  
Keyword(s):  
Continuous Caster ◽  
Three Dimensional ◽  
Electromagnetic Stirring ◽  
Minor Effect ◽  
Deep Insight ◽  
The Third ◽  
Recirculation Zones ◽  
Central Cross Section ◽  
A Minor ◽  
Insight Into

Mold electromagnetic stirring (M-EMS) has been widely used in many continuous casters. In order to have a deep insight into the collision-coalescence among inclusions under M-EMS by a Eulerian approach, the effects of Archimedes electromagnetic force on the inclusion are expressed by three-dimensional Archimedes electromagnetic slipping velocity and Archimedes electromagnetic collision. Numerical results show that a turbulent collision is the most important factor to cause inclusions to collide with each other, Archimedes electromagnetic collision has a minor effect, Stokes collision is the third factor, and Brownian can be ignored. In the case of M-EMS, there are two recirculation zones above and below the M-EMS central cross-section, and the inclusion spatial distributions have the inverted U-shape.

Simulation of the Effect of Season of Fire on Post-Fire Seedling Emergence of Two Banksia Species Based on Long-Term Rainfall Records

1992 ◽  
Vol 40 (1) ◽  
pp. 75 ◽  
Author(s):  
RA Bradstock ◽  
M Bedward
Keyword(s):  
Seedling Emergence ◽  
Soil Surface ◽  
Fire Season ◽  
Fire Intensity ◽  
Minor Effect ◽  
Seed Mortality ◽  
South Wales ◽  
Equal Importance ◽  
High Level ◽  
A Minor

Simulations were used to investigate the effect of season of fire on seedling emergence in Banksia ericifolia and B. serrata in the Sydney region, New South Wales. The simulations were based on models of soil-surface moisture in response to rainfall, seedling emergence response to soil moisture and post-fire seed release from fruits as determined by fire intensity, derived from field and laboratory studies. Fires were modelled on the first day of each calendar month for a 50-year period. Levels of post-fire seedling emergence were calculated using rainfall data from the Sydney Observatory for the corresponding period (1931-1980). Trends in seedling emergence as a function of month of fire were examined. Alternative sets of simulations were performed to assess the effect of variations in post-dispersal seed mortality, fire intensity and induced summer dormancy. In both species, mean emergence was affected by season of fire only when a 10% per month level of post-dispersal seed mortality was simulated (there was no fire-season effect at lower mortality levels). Highest predicted emergence occurred after summer fires and lowest emergence after winter fires. A reduction in rate of seed release (lower intensity fire) and induced seed dormancy in summer also had a minor effect with respect to fire-season in B. ericifolia. Reported levels of post-dispersal seed mortality in Banksia species are often high, and therefore, the simulations suggested that there will be an effect of fire season on seedling emergence. However, given the high level of year to year variation in seasonal rainfall in the Sydney region, fire-season effects are not predictable in the short term. In the longer term, the timing of fire relative to sequences of wet and dry years may be of equal importance to season of fire in its effect on populations of these species.

scholarly journals Drop Size Distribution Broadening Mechanisms in a Bin Microphysics Eulerian Model

2020 ◽  
Vol 77 (9) ◽  
pp. 3249-3273
Author(s):  
Lianet Hernández Pardo ◽  
Hugh Morrison ◽  
Luiz A. T. Machado ◽  
Jerry Y. Harrington ◽  
Zachary J. Lebo
Keyword(s):  
Drop Size ◽  
Three Dimensional ◽  
Cloud Droplet ◽  
Minor Effect ◽  
Physically Based ◽  
High Supersaturation ◽  
Drop Size Distributions ◽  
Cloud Activation ◽  
Bin Microphysics ◽  
A Minor

Abstract In this study, processes that broaden drop size distributions (DSDs) in Eulerian models with two-moment bin microphysics are analyzed. Numerous tests are performed to isolate the effects of different physical mechanisms that broaden DSDs in two- and three-dimensional Weather Research and Forecasting Model simulations of an idealized ice-free cumulus cloud. Sensitivity of these effects to modifying horizontal and vertical model grid spacings is also examined. As expected, collision–coalescence is a key process broadening the modeled DSDs. In-cloud droplet activation also contributes substantially to DSD broadening, whereas evaporation has only a minor effect and sedimentation has little effect. Cloud dilution (mixing of cloud-free and cloudy air) also broadens the DSDs considerably, whether or not it is accompanied by evaporation. This mechanism involves the reduction of droplet concentration from dilution along the cloud’s lateral edges, leading to locally high supersaturation and enhanced drop growth when this air is subsequently lifted in the updraft. DSD broadening ensues when the DSDs are mixed with those from the cloud core. Decreasing the horizontal and vertical model grid spacings from 100 to 30 m has limited impact on the DSDs. However, when these physical broadening mechanisms (in-cloud activation, collision–coalescence, dilution, etc.) are turned off, there is a reduction of DSD width by up to ~20%–50% when the vertical grid spacing is decreased from 100 to 30 m, consistent with effects of artificial broadening from vertical numerical diffusion. Nonetheless, this artificial numerical broadening appears to be relatively unimportant overall for DSD broadening when physically based broadening mechanisms in the model are included for this cumulus case.

A Barium Vanadium(V) Selenite Hydrate, Ba(VO2)2(SeO3)2·H2O: A Novel 3D Polymer of Cross-Linked Sheets with Embedded ···V–O–V··· 21 Helices

2014 ◽  
Vol 67 (12) ◽  
pp. 1878 ◽  
Author(s):  
Kieryn L. Kilminster ◽  
Francis J. Lincoln ◽  
Brian W. Skelton ◽  
Allan H. White
Keyword(s):  
Single Crystal ◽  
Three Dimensional ◽  
The Other ◽  
Formula Unit ◽  
Asymmetric Unit ◽  
X Ray ◽  
Crystallographic Symmetry ◽  
Pentavalent Vanadium ◽  
A Minor

The characterisation, by a single-crystal X-ray study at ~150 K, of brown acicular crystals of barium(ii) bis(dioxovanadium(v)) bis(selenite(iv)) monohydrate, BaSe2V2O10·H2O, obtained as a minor product of the synthesis of the previously reported ‘Ba(VO)2(SeO3)2(HSeO3)2’, is recorded. Crystals are monoclinic, P21/c, a = 10.803(2), b = 5.1126(8), c = 17.905(3) Å, β = 92.048(2)°, V = 988.3(3) Å3, 2456 independent diffractometer reflections refining to R1 = 0.032, wR2 = 0.084. A single BaV2Se2O11H2 formula unit, devoid of crystallographic symmetry, comprises the asymmetric unit of the structure, which is a three-dimensional polymer, with component sheets parallel to the crystallographic b axis, containing pentavalent vanadium atoms, one five-, the other six-coordinate, linked by selenite pyramids.

Guided surgery with 3D printed device: a case report

2020 ◽  
Author(s):  
Michelle Carvalho de Sales ◽  
Rafael Maluza Flores ◽  
Julianny da Silva Guimaraes ◽  
Gustavo Vargas da Silva Salomao ◽  
Tamara Kerber Tedesco ◽  
...  
Keyword(s):  
Operating Time ◽  
Three Dimensional ◽  
Conventional Technique ◽  
Cervical Region ◽  
Mean Deviation ◽  
Apical Region ◽  
Virtual Planning ◽  
Surgical Guide ◽  
Surgical Guides ◽  
High Level

Dental surgeons need in-depth knowledge of the bone tissue status and gingival morphology of atrophic maxillae. The aim of this study is to describe preoperative virtual planning of placement of five implants and to compare the plan with the actual surgical results. Three-dimensional planning of rehabilitation using software programs enables surgical guides to be specially designed for the implant site and manufactured using 3D printing. A patient with five teeth missing was selected for this study. The patient’s maxillary region was scanned with CBCT and a cast model was produced. After virtual planning using ImplantViewer, five implants were placed using a printed surgical guide. Two weeks after the surgical procedure, the patient underwent another CBCT scan of the maxilla. Statistically significant differences were detected between the virtually planned positions and the actual positions of the implants, with a mean deviation of 0.36 mm in the cervical region and 0.7 mm in the apical region. The surgical technique used enables more accurate procedures when compared to the conventional technique. Implants can be better positioned, with a high level of predictability, reducing both operating time and patient discomfort.

Improvement of monitoring of tertiary filtration with particle counting

2006 ◽  
Vol 6 (1) ◽  
pp. 1-9
Author(s):  
V. Miska ◽  
J.H.J.M. van der Graaf ◽  
J. de Koning
Keyword(s):  
Particle Surface ◽  
Minor Effect ◽  
Particle Size Distributions ◽  
Particle Volume ◽  
Mass Distributions ◽  
Particle Counting ◽  
Total Particle ◽  
Particle Counts ◽  
A Minor ◽  
Sample Dilution

Nowadays filtration processes are still monitored with conventional analyses like turbidity measurements and, in case of flocculation–filtration, with phosphorus analyses. Turbidity measurements have the disadvantage that breakthrough of small flocs cannot be displayed, because of the blindness regarding changes in the mass distributions. Additional particle volume distributions calculated from particle size distributions (PSDs) would provide a better assessment of filtration performance. Lab-scale experiments have been executed on a flocculation–filtration column fed with effluent from WWTP Beverwijk in The Netherlands. Besides particle counting at various sampling points, the effect of sample dilution on the accuracy of PSD measurements has been reflected. It was found that the dilution has a minor effect on PSD of low turbidity samples such as process filtrate. The correlation between total particle counts, total particle volume (TPV) and total particle surface is not high but is at least better for diluted measurements of particles in the range 2–10 μm. Furthermore, possible relations between floc-bound phosphorus and TPV removal had been investigated. A good correlation coefficient is found for TPV removal versus floc-bound phosphorus removal for the experiments with polyaluminiumchloride and the experiments with single denitrifying and blank filtration.

scholarly journals Linkage mapping identifies a non-synonymous mutation in FLOWERING LOCUS T (FT-B1) increasing spikelet number per spike

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Jonathan Brassac ◽  
Quddoos H. Muqaddasi ◽  
Jörg Plieske ◽  
Martin W. Ganal ◽  
Marion S. Röder
Keyword(s):  
Flowering Time ◽  
Aspartic Acid ◽  
Synonymous Substitution ◽  
Minor Effect ◽  
Phenotypic Variance ◽  
Spikelet Number ◽  
Wheat Varieties ◽  
Trait Locus ◽  
A Minor ◽  
Spikelet Number Per Spike

AbstractTotal spikelet number per spike (TSN) is a major component of spike architecture in wheat (Triticumaestivum L.). A major and consistent quantitative trait locus (QTL) was discovered for TSN in a doubled haploid spring wheat population grown in the field over 4 years. The QTL on chromosome 7B explained up to 20.5% of phenotypic variance. In its physical interval (7B: 6.37–21.67 Mb), the gene FLOWERINGLOCUST (FT-B1) emerged as candidate for the observed effect. In one of the parental lines, FT-B1 carried a non-synonymous substitution on position 19 of the coding sequence. This mutation modifying an aspartic acid (D) into a histidine (H) occurred in a highly conserved position. The mutation was observed with a frequency of ca. 68% in a set of 135 hexaploid wheat varieties and landraces, while it was not found in other plant species. FT-B1 only showed a minor effect on heading and flowering time (FT) which were dominated by a major QTL on chromosome 5A caused by segregation of the vernalization gene VRN-A1. Individuals carrying the FT-B1 allele with amino acid histidine had, on average, a higher number of spikelets (15.1) than individuals with the aspartic acid allele (14.3) independent of their VRN-A1 allele. We show that the effect of TSN is not mainly related to flowering time; however, the duration of pre-anthesis phases may play a major role.

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