Single Structure Type Research Articles

Predicting spinel solid solutions using a random atom substitution method.

Exploration of chemical composition and structural configuration space is the central problem in crystal structure prediction. Even in limiting structure space to a single structure type, many different compositions and configurations are possible. In this work, we attempt to address this problem using an extension to the existing ChemDASH code in which variable compositions can be explored. We show that ChemDASH is an efficient method for exploring a fixed-composition space of spinel structures and build upon this to include variable compositions in the Mn-Fe-Zn-O spinel phase field. This work presents the first basin-hopping crystal structure prediction method that can explore variable compositions.

Decreasing Carbon Footprint of Block of Flats – Concrete Technology Possibilities

Abstract Construction business along with other businesses have set carbon neutrality goals in the following years. To reach these goals a lot needs to be done fairly quickly. The high impact of concrete production on carbon emissions has been known for years and solutions for this problem are studied in this paper through supplementary cementing materials. Ordinary Portland cement can be replaced partly but not completely with cement replacing materials since the strength properties are lost at replacement level higher than 80%. These replacing binders can be pulverized fly ash, blast furnace slag or silica fume. The use of the new low-carbon products can half the embodied carbon for the bearing frame of the building. The total area of a certain structure type is important since replacing its cement can have much higher impact on the total carbon footprint than replacing it for a single structure type that has fairly small area in the building.

Methods for Synthesis of Molecular Materials with Unique Physical Properties

The authors discovered and investigated new types of stable heterometallic carboxylate complexes in which divalent transition metal atoms of the 4th period of the Periodic Table of Chemical Elements (V, Co, Ni, Cu, Zn) combine with atoms of lithium, magnesium, calcium or rare earth elements. These polynuclear heterometallic compounds retain their structure under conditions when the homometallic compounds of these transition metals decompose to mononuclear complexes. The different metals combination in one molecule allows us to use the obtained heterometallic compounds for producing disperse and film oxide materials, and bimetallic oxide catalysts. The stability of the complexes allows to immobilize them in various matrices and to assemble 3D polymer structures on their base. Since the metal ions under consideration (V, Co, Ni, Cu, Zn) are capable to form isostructural heterometallic compounds, it becomes possible to obtain compounds within a single structural type with a given combination of physical properties, determined by the nature of the metal ions.

The solid solutions based on lanthanum manganite as the cathod materials for bismuth-containing solid electrolytes

Substituted lanthanum manganites with the general composition La1–x Bi x Mn1–y Fe(Ni,Cu)yO3 + δ and unit cells in rhombohedral (space group (sp. gr.) R-3c) and/or orthorhombic (sp. gr. Pnma) symmetry are synthesized and attested. They are characterized by permanent excessive oxygen nonstoichiometry within a single structure type at room temperature, independent of the dopant concentration. These materials are adequately mechanically compatible with bismuth niobates. The interval of their chemical compatibility with bismuth-containing compounds is limited by 700–800°C. In this region, the conductivity of composites of substituted lanthanum manganites and bismuth-containing electrolytes is higher as compared with individual compounds. The use of individual manganites or their composites as the electrodes in cells with bismuthcontaining electrolytes increases the total conductivity of the cells.

Differential use of highway underpasses by bats

Roads can form barriers to movement for many species, and may reduce the ability of individuals to access foraging and breeding habitat. The impacts of roads on terrestrial fauna has been well studied, however little is known of the impact of roads on insectivorous bats. Wildlife crossing structures (e.g. fauna underpasses) may reduce the barrier impacts of roads and improve connectivity across roads. Use of underpasses by wildlife likely varies among species depending on their movement behaviour. In this study, we investigated whether the flight patterns of insectivorous bats influenced their use of underpasses. We monitored bat activity under and above 6 open-span bridges, 6 box culverts and 6 unmitigated sites along a major highway in Australia. We used Poisson regression models within a Bayesian framework of inference to compare the activity of 12 bat species (grouped into three guilds based on their flight patterns: clutter-adapted, edge-adapted, and open-adapted species) under the structures, over the road above the structures, above unmitigated segments of the highway, and in the vegetation adjacent to the roads. Bats were less active above the road than they were in the surrounding vegetation or under bridges. Two of the three guilds (i.e. seven species) crossed the highway more under bridges than they did under culverts or by going over the road, which suggests that bridges may reduce barrier effects of the road better than culverts. Installing bridges instead of culverts may better reduce the impacts of roads on multiple insectivorous bats species with a single structure type.

Vacancy pairing and superstructure in the high-pressure silicate K1.5Mg2Si2O7H0.5: a new potential host for potassium in the deep Earth.

The high-pressure silicate K1.5Mg2Si2O7H0.5, synthesized and characterized by Welch et al. [(2012), Am. Mineral. 97, 1849-1857], has been re-examined with the aim of determining the nature of the superstructure noted in their study. The composition corresponds to a 1:1 combination of KMg2Si2O7H and K2Mg2Si2O7 end-members, but it is not a solid solution. Single-crystal X-ray diffraction data for one of the original K1.5Mg2Si2O7H0.5 crystals synthesized at 16 GPa/1573 K, has been collected using a much longer exposure time in order to improve the intensity statistics of weak superlattice reflections identified by Welch et al. (2012). The superstructure has been determined using a superspace approach as having the superspace group Cmcm(0,β,0)00s and t0 = 1/16 with refined parameters a = 8.7623 (10), b = 5.0703 (7), c = 13.2505 (11) Å, V = 588.69 (12) Å3. This structure corresponds to one with the conventional space group Pbnm and unit-cell parameters a = 8.7623 (10), b = 20.281 (3), c = 13.2505 (11) Å, V = 2354.7 (5) Å3 and is based upon a super-sheet motif in which ordering involves rows of pairs of vacant interlayer K sites. This is the third topologically distinct structure type for the KMg2Si2O7H-K2Mg2Si2O7 join and suggests that there is very limited solid solution, and so it can be expected that each of the three structures (P63cm, P\bar 3 1m and Pbnm) has its own stability field, rather than being part of a continuous compositional series based upon a single structure type. As such, K1.5Mg2Si2O7H0.5 should be considered as a potentially significant host of K in the Earth's mantle.

That’s No Moon: It’s a Molecular Capsule

In this issue of Chem , Fujita et al. have produced the largest synthetic self-assembled capsule to date through subtle modification of the flexibility and geometry of its constituent ligands.

일본 정신보건복지센터의 운영체계 및 시설유형 분석연구 (1)

Purpose : Mental health service desire has been diversified according to the increase of economic level and rapid social change. Mental Health and Welfare Center(MHWC) is a provider of mental health services in Japan. This is a basic stage study which will suggest the architectural planning guidelines for MHWC. Methods : Data were collected through literature research, field surveys, and expert interviews to 69 MHWC in Japan. 1) Research for the policy and legal aspects of mental health support system. 2) Research for structural aspects of MHWC: Characteristics of establishment, management, and regional factors. 3) Research for the physical environment aspects of MHWC: Classification and evaluation of MHWC's Type by locational characteristics in Japan. Results : The result of this study can be summarized into three points. The first one, Mental Health and Welfare Center's service has being expanded to suicide, depression and stress from chronic mental illness, to reflect social needs. The second one, The average population of area installed at Mental Health and Welfare Center was 2,307,570 person, and average area of the regions were <TEX>$5,745m^2$</TEX>. The third one, Mental Health and Welfare Center is divided into single-structure type and combine-structure type. And combine-structure type is divided into medical-combine type, welfare-combine type, and public-combine type.

A single structural type in the regular surface layer of Aeromonas salmonicida

The surface protein array of Aeromonas salmonicida (or A-layer) appears, in negatively stained preparations, as two distinct patterns, type I and type II. Type I patterns were restricted to, and predominated in, darkly stained areas, whereas lighter staining regions exclusively displayed type II patterns. The type I morphology was faithfully reproduced in computer-simulated superimpositions of type II patterns, as was the intermediate transition zone frequently seen between the two patterns. Variations in the lattice constant of both patterns, presumably due to artifactual flattening, demonstrated that these patterns could not be distinguished on this basis. The conceptual model presented points to the type II pattern as the only single A-layer structural type. We propose the use of the terms type 1/type II to exclusively describe the morphological patterns that appear upon negative staining and the open/closed nomenclature to describe the conformations that a single structural type can adopt.

Effects of Vagotomy on the Ultrastructure of the Nerves of Dog Stomach

The effects of vagotomy on the gastric neuronal apparatus have been studied. A portion, but not all, of the presynaptic terminals on neurons of the Auerbach's and Meissner's plexuses degenerated. The residual terminals presumably arose from intrinsic neurons. The neurons were of several types: (D large motor neurons with synaptic connections which could not be distinguished from one another morphologically as to excitatory or inhibitory function, and which underwent postdenervation changes; (2) presumed sensory neurons without detectable synaptic connections, which were unaffected by vagotomy, and which could be subdivided into two types. Other neuronal profiles with many large vesicles were observed only after vagotomy. The nerves to muscle layers contained small agranular vesicles and large dense-cored vesicles, sometimes with a predominance of one vesicle type or the other. It was not possible to determine whether these represented two morphological nerve types, or sampling variations from a single structural type. Neither vesicle type seemed to be selectively affected by vagotomy. A few axons, presumably adrenergic, with small agranular vesicles, were observed, chiefly near blood vessels but also a few in the plexuses and in the muscle layers of the pyloric region. They were not obviously affected by vagotomy.

Textile and Basketry Impressions from Icehouse Bottom, Tennessee

AbstractAnalysis of a series of negative impressions in fired clay recovered during the 1975 excavations at Icehouse Bottom (40MR23), Tennessee, indicates the production and/or use of both single element textiles and basketry at that site. One type of single element textile, knotted looping, is represented by a single specimen while one of the three major subclasses of basketry is also present. The latter includes 19 samples of a single structural type of twining. The technical characteristics of this, the oldest well dated "perishable" assemblage from east of the Mississippi River, are discussed and the assemblage is briefly compared to others in eastern and western North America.

A single structural type in the series of oxyorthosilicates of the rare earth elements

We have carried out a roentgenostructural analysis of monocrystals and polycrystals of the oxyorthosilicates of rare earth elements of the third group. of rare earth elements of the third group.