Lithofacies and petrochemical characterization of volcano-sedimentary sequence of Chandil Formation around Kharidih-Bareda area, Seraikela-Kharsawan District, Jharkhand: implications for uranium mineralization

Mesoproterozoic Chandil Formation (ca. 1600 Ma) of North Singhbhum Mobile Belt record numerous features of felsic volcaniclastics and felsic to intermediate volcanics preserved in the central sector of the fold belt around Kharidih-Bareda area, Seraikela-Kharsawan district, Jharkhand. The felsic volcanic rocks exhibit flow bands, autoclasts and layering of crystal mushes revealing viscous nature of eruptives. The volcaniclastic sediments comprise of significant proportion of volcanic epiclasts and accidental lithic fragments. These volcaniclastics have been categorized into five prominent lithofacies viz, stratified lapilli tuff, banded tuff, tuff with penecontemporaneous deformation, welded lapilli stones, vitric tuff and volcanic bombs by field and petrographic studies of outcrops and subsurface borehole cores. The welded lapilli tuffs display fiamme and eutaxitic texture. Interlayering of the volcaniclastics, which are most often pyrite-rich, with psamo-pelitic lithology like carbonaceous phyllite, variegated phyllite, quartzite and minor limestone is suggestive of marine euxenic depositional environment. Petrographic study of the volcaniclastics indicated presence of glass shards, garnet phenocrysts, spherules of tremolite, ovoid to lenticular accretionary lapilli along with devitrified glassy material. Compositionally these felsic volcanics and volcaniclastics are rhyodacitic to andesitic in nature with peraluminous to meta aluminous in character. A/CNK values vary from 0.52 to 2.42 in felsic volcanics and from 0.12 to 1.63 in volcaniclastics. Signatures of arc magmatism is indicated by low concentration of HFS elements such as Nb (5-17 ppm), Ga (11-17 ppm) and Y (5-28 ppm). Elevated intrinsic content of uranium (3-8 ppm), Th/U ratio ranging from 1.2 to 13.2, presence of metamict allanite and zircon in volcanics and volcaniclastics reveal their suitability as a prospective source for search of uranium mineralization. The volcanic-volcaniclastic-clastic association of the Chandil Formation provides an ideal situation where provenance and province both are available. Thus, suitable litho-structural locales such as the concealed shear zones sympathetic to the Dalma thrust and South Purulia Shear Zone within the volcano-sedimentary package of Chandil Formation may be targeted as preferable sites for locating concealed uranium mineralization.

Bioactive Glass—An Extensive Study of the Preparation and Coating Methods

Diseases or complications that are caused by bone tissue damage affect millions of patients every year. Orthopedic and dental implants have become important treatment options for replacing and repairing missing or damaged parts of bones and teeth. In order to use a material in the manufacture of implants, the material must meet several requirements, such as mechanical stability, elasticity, biocompatibility, hydrophilicity, corrosion resistance, and non-toxicity. In the 1970s, a biocompatible glassy material called bioactive glass was discovered. At a later time, several glass materials with similar properties were developed. This material has a big potential to be used in formulating medical devices, but its fragility is an important disadvantage. The use of bioactive glasses in the form of coatings on metal substrates allows the combination of the mechanical hardness of the metal and the biocompatibility of the bioactive glass. In this review, an extensive study of the literature was conducted regarding the preparation methods of bioactive glass and the different techniques of coating on various substrates, such as stainless steel, titanium, and their alloys. Furthermore, the main doping agents that can be used to impart special properties to the bioactive glass coatings are described.

Environmentally Clean Ceramics Manufacturing With Application of Hazardous Car Production Mud and Galvanic Process Glass Waste

It was developed new ceramics composites with hazardous car production mud (CPM) and galvanic process glass waste with high content of heavy metals. They were applied as valuable components of red ceramics sintered at 700°, 750°, 800°, 850°, 900°, and 950°C to provide flexural resistance of up to 17.6 MPa, water absorption at 950°C 6.53 -10.45%, linear shrinkage – 5.24-6.29%, density 2.7 – 3.2 g/cm³, and dilatation coefficient 5.3 -13.8%. Structure formation studies by the XRD, SEM, EDS, and LAMMA methods demonstrated the synthesis of amorphous glassy material with small inclusion of mullite Al6Si2O13. Car production mud and galvanic process glass waste play the role of the intensifiers of the ceramics’ structures formation processes. The ceramics' leaching and solubility tests by the atomic absorption spectroscopy method showed strong chemical bond of heavy metals of the hazardous raw materials in insoluble structures. According to Brazilian standards, they can be used to produce tiles, bricks, blocks, and similar materials with high environmental eficiency.

Accidental synthesis of a previously unknown quasicrystal in the first atomic bomb test

The first test explosion of a nuclear bomb, the Trinity test of 16 July 1945, resulted in the fusion of surrounding sand, the test tower, and copper transmission lines into a glassy material known as “trinitite.” Here, we report the discovery, in a sample of red trinitite, of a hitherto unknown composition of icosahedral quasicrystal, Si61Cu30Ca7Fe2. It represents the oldest extant anthropogenic quasicrystal currently known, with the distinctive property that its precise time of creation is indelibly etched in history. Like the naturally formed quasicrystals found in the Khatyrka meteorite and experimental shock syntheses of quasicrystals, the anthropogenic quasicrystals in red trinitite demonstrate that transient extreme pressure–temperature conditions are suitable for the synthesis of quasicrystals and for the discovery of new quasicrystal-forming systems.

Comparative study of photoinduced surface-relief-gratings on azo polymer and azo molecular glass films

A representative azo polymer (BP-AZ-CA) and a typical azo molecular glass (IAC-4) were studied for their surface-relief-grating formation behavior to provide a deep understanding of the clear distinction between these two types of glassy material.

A brief history of porcelain enamel: from artistic enamel to technical enamelling

Porcelain enamel is a glassy material deposited on a metallic substrate and fired at high temperatures (500-900 °C) to form a stable and permanent bond with it through chemical-physical reaction. This coating was developed in ancient times for decorative purposes and it was mainly used to embellish precious objects with colourful and glossy finishing as if to imitate the shining of precious stones. Only from 1760 enamelling of metal objects began to play a technical role. Nowadays vitreous enamel coatings are widely used and appreciated for high-duty technological applications, as they provide good corrosion protection of the covered substrates and they can withstand chemical attack, abrasion, and degradation caused by external agents, maintaining their aesthetical properties unchanged in time. This work is to introduce and describe the history of enamelling from ancient times to the modern era, revealing the glorious past of this material for decorative purposes and its use as a technical coating from the First Industrial Revolution onward.   

Scaling Effects on the Residual Thermomechanical Stress During Ice-Free Cooling to Storage Temperature

Cryopreservation via vitrification (glass formation) is a promising approach for long-term preservation of large-size tissues and organs. Unfortunately, thermomechanical stress, which is driven by the tendency of materials to change size with temperature, may lead to structural failure. This study focuses on analysis of thermomechanical stress in a realistic, pillow-like shape cryobag as it is cooled to cryogenic storage, subject to sufficiently high cooling rates to facilitate vitrification. Contrary to common perception, it is demonstrated in this study that the maximum stress in the specimen does not necessarily increase with increasing size of the specimen. In fact, the maximum stress is affected by the combination of two competing effects, associated with the extent of the temperature gradients within the specimen and its overall volume. On one hand, the increase in specimen size gives rise to more prominent temperature gradients, which can intensify the thermomechanical stress. On the other hand, the temperature distribution at the core of larger specimens is more uniform, which leads to a larger portion of the specimen transitioning from fluid to a glassy material almost instantaneously, which carries a moderating effect on the overall mechanical stress at the glassy state (i.e., lower residual stress). In conclusion, this study demonstrates the role of container shape optimization in reducing the thermomechanical stress during cooling.

First-principles experimental demonstration of ferroelectricity in a thermotropic nematic liquid crystal: Polar domains and striking electro-optics

We report the experimental determination of the structure and response to applied electric field of the lower-temperature nematic phase of the previously reported calamitic compound 4-[(4-nitrophenoxy)carbonyl]phenyl2,4-dimethoxybenzoate (RM734). We exploit its electro-optics to visualize the appearance, in the absence of applied field, of a permanent electric polarization density, manifested as a spontaneously broken symmetry in distinct domains of opposite polar orientation. Polarization reversal is mediated by field-induced domain wall movement, making this phase ferroelectric, a 3D uniaxial nematic having a spontaneous, reorientable polarization locally parallel to the director. This polarization density saturates at a low temperature value of ∼6 µC/cm2, the largest ever measured for a fluid or glassy material. This polarization is comparable to that of solid state ferroelectrics and is close to the average value obtained by assuming perfect, polar alignment of molecular dipoles in the nematic. We find a host of spectacular optical and hydrodynamic effects driven by ultralow applied field (E ∼ 1 V/cm), produced by the coupling of the large polarization to nematic birefringence and flow. Electrostatic self-interaction of the polarization charge renders the transition from the nematic phase mean field-like and weakly first order and controls the director field structure of the ferroelectric phase. Atomistic molecular dynamics simulation reveals short-range polar molecular interactions that favor ferroelectric ordering, including a tendency for head-to-tail association into polar, chain-like assemblies having polar lateral correlations. These results indicate a significant potential for transformative, new nematic physics, chemistry, and applications based on the enhanced understanding, development, and exploitation of molecular electrostatic interaction.

Fabrication of Metastable Crystalline Nanocomposites by Flash Annealing of Cu47.5Zr47.5Al5 Metallic Glass Using Joule Heating

Flash Joule-heating was applied to the Cu47.5Zr47.5Al5 metallic glass for designing fully crystalline metastable nanocomposites consisting of the metastable B2 CuZr and low-temperature equilibrium Cu10Zr7 phases. The onset of crystallization was in situ controlled by monitoring resistivity changes in the samples. The effect of heating rate and annealing time on the volume fraction of the crystalline phases and mechanical properties of the nanocomposites was studied in detail. Particularly, an increase of the heating rate and a decrease of the annealing time lead to a lower number of equilibrium Cu10Zr7 precipitates and an increase of tensile ductility. Tailoring of these non-equilibrium microstructures and mechanical properties may not be possible unless one starts with a fully glassy material that opens new perspectives for designing metastable nanomaterials with unique physical properties.

Two Contrasting Provenances of Prehistoric Obsidian Artifacts in South Korea: Mineralogical and Geochemical Characteristics

Two provenances – Mount Baekdusan near Sino-Korean border and Kyushu of southwest Japan – are well known for Korean prehistoric obsidian artifacts. We examined the mineralogical and geochemical characteristics of the Baekdusan obsidians and the Kyushu obsidians. Though obsidians are of glassy material, microlites are easily found in the host matrix. Fe-oxides are the most abundant microlite phase, with a lesser amount of clinopyroxene, feldspar, and biotite. It is notable that the texture and chemical composition of the microlites in the Baekdusan obsidians are quite different from those in the Kyushu obsidians. Clinopyroxene in the Baekdusan obsidians occurs as oikocryst enclosing smaller Fe-oxides, and has the composition of hedenbergite to augite. On the other hand, clinopyroxene in the Kyushu obsidians is compositionally of clinoferrosilite, and shows intergrowth and/or overgrowth textures with Fe-oxides. Feldspar microlites in the Baekdusan obsidians are generally of sanidine to anorthoclase, whereas those in the Kyushu obsidians of oligoclase. Biotite microlites are often found in the Kyushu obsidians, but absent in the Baekdusan obsidians. Also, there exist prominent geochemical contrasts between the Baekdusan obsidians and the Kyushu obsidians. At the similar SiO2 range of 74 to 78 wt.% the host glasses of the Baekdusan obsidians have higher contents of TiO2, total FeO, K2O, Nb, Hf, Zr, Ta, Y and rare earth elements (REEs) than those of the Kyushu obsidians. The overall mineralogical and geochemical contrasts for the Baekdusan and Kyushu obsidians seem to reflect different parental magma composition and crystallization environment. This distinction can be used to establish the provenance of the obsidian artifacts from the prehistoric sites in the Korean Peninsula as well as contiguous areas such as China, Japan, and Russia.