scholarly journals Mineralogy, Crystallography and Structural Complexity of Natural Uranyl Silicates

Minerals ◽  
2018 ◽  
Vol 8 (12) ◽  
pp. 551 ◽  
Author(s):  
Jakub Plášil
Keyword(s):  
Structural Complexity ◽  
Point Of View ◽  
Hydrothermal Fluids ◽  
Uranium Deposits ◽  
Silicate Minerals ◽  
Natural Systems ◽  
Naturally Occurring ◽  
Primary Si ◽  
Mineral Associations ◽  
Uranyl Silicates

Naturally occurring uranyl silicates are common constituents of the oxidized parts (i.e., supergene zone) of various types of uranium deposits. Their abundance reflects the widespread distribution of Si4+ in the Earth’s crust and, therefore, in groundwaters. Up to date, 16 uranyl silicate minerals are known. Noteworthy is that the natural uranyl silicates are not extremely diverse regarding their crystal structures; it is a result of possible concentrations (activity) of Si4+ in aqueous solutions derived from dissolution of primary Si minerals or the composition of late hydrothermal fluids. Therefore, in natural systems, we distinguish in fact among two groups of uranyl silicate minerals: uranophane and weeksite-group. They differ in U:Si ratio (uranophane, 1:1; weeksite, 2:5) and they form under different conditions, reflected in distinctive mineral associations. An overview of crystal-chemistry is provided in this paper, along with the new structure data for few members of the uranophane group. Calculations of the structural complexity parameters for natural uranyl silicates are commented about as well as other groups of uranyl minerals; these calculations are also presented from the point of view of the mineral paragenesis and associations.

scholarly journals Using virtual reality to estimate aesthetic values of coral reefs

2018 ◽  
Vol 5 (4) ◽  
pp. 172226 ◽  
Author(s):  
Julie Vercelloni ◽  
Sam Clifford ◽  
M. Julian Caley ◽  
Alan R. Pearse ◽  
Ross Brown ◽  
...  
Keyword(s):  
Coral Reef ◽  
Coral Reefs ◽  
Structural Complexity ◽  
Natural Environments ◽  
Natural Ecosystems ◽  
Aesthetic Value ◽  
Natural Systems ◽  
Holistic Conservation ◽  
Past Experiences ◽  
Aesthetic Values

Aesthetic value, or beauty, is important to the relationship between humans and natural environments and is, therefore, a fundamental socio-economic attribute of conservation alongside other ecosystem services. However, beauty is difficult to quantify and is not estimated well using traditional approaches to monitoring coral-reef aesthetics. To improve the estimation of ecosystem aesthetic values, we developed and implemented a novel framework used to quantify features of coral-reef aesthetics based on people's perceptions of beauty. Three observer groups with different experience to reef environments (Marine Scientist, Experienced Diver and Citizen) were virtually immersed in Australian's Great Barrier Reef (GBR) using 360° images. Perceptions of beauty and observations were used to assess the importance of eight potential attributes of reef-aesthetic value. Among these, heterogeneity, defined by structural complexity and colour diversity, was positively associated with coral-reef-aesthetic values. There were no group-level differences in the way the observer groups perceived reef aesthetics suggesting that past experiences with coral reefs do not necessarily influence the perception of beauty by the observer. The framework developed here provides a generic tool to help identify indicators of aesthetic value applicable to a wide variety of natural systems. The ability to estimate aesthetic values robustly adds an important dimension to the holistic conservation of the GBR, coral reefs worldwide and other natural ecosystems.

scholarly journals Sandstone-Hosted Uranium Deposits as a Possible Source for Critical Elements: The Eureka Mine Case, Castell-Estaó, Catalonia

Minerals ◽  
2019 ◽  
Vol 10 (1) ◽  
pp. 34 ◽  
Author(s):  
Montgarri Castillo-Oliver ◽  
Joan Carles Melgarejo ◽  
Lisard Torró ◽  
Cristina Villanova-de-Benavent ◽  
Marc Campeny ◽  
...  
Keyword(s):  
Organic Matter ◽  
Low Temperature ◽  
Black Shales ◽  
Hydrothermal Fluids ◽  
Uranium Deposits ◽  
Critical Metals ◽  
Fine Grained ◽  
Critical Elements ◽  
By Products ◽  
Red Bed

The Eureka deposit in Castell-estaó in the Catalan Pyrenees is a Cu–U–V deposit, hosted by Triassic red-bed sandstones, and classified here as a low-temperature, sandstone-hosted stratabound metamorphite U deposit. The main mineralisation is stratabound, related to coal-bearing units and produced during the Alpine deformation by migration of hydrothermal fluids. In this stage, the original sedimentary and diagenetic components (quartz and calcite, micas, hematite and locally apatite) were replaced by a complex sequence of roscoelite, fine-grained REE phosphates, sulphides and Ni–Co arsenides and sulpharsenides, Ag–Pb selenides, bismuth phases, sulphosalts and uraninite. The black shales of the Silurian sediments underlying the deposit and the nearby Carboniferous volcanoclastic rocks are interpreted as the source of the redox-sensitive elements concentrated in Eureka. The sulphur source is related to leaching of the evaporitic Keuper facies. The REE transport would be facilitated by SO4-rich solutions. The reduction of these solutions by interaction with organic matter resulted in the widespread precipitation of REE and redox-sensitive elements, including many critical metals (V, Bi, Sb, Co), whereas barite precipitated in the oxidized domains. The occurrence of similar enrichments in critical elements can be expected in other similar large uranium deposits, which could be a source of these elements as by-products.

‘from a musical point of view, the world is musical at any given moment’: an interview with bill fontana

2005 ◽  
Vol 10 (2) ◽  
pp. 97-101 ◽  
Author(s):  
jøran rudi
Keyword(s):  
New York ◽  
New York City ◽  
York City ◽  
Large Scale ◽  
Urban Environments ◽  
Point Of View ◽  
Naturally Occurring ◽  
The World ◽  
American Composer ◽  
Brooklyn Bridge

bill fontana is an american composer and artist who has been working with large-scale sound installations since the 1970s. in his installations he recontextualises sounds by transmitting them from one location to another, and uses the transported sounds as acoustical ‘overlay’, masking the sounds naturally occurring in the installation spaces. his installations often occur in central urban environments, and he has, for example, been commissioned in conjunction with the fifty-year anniversary of d-day (1994, paris), and the 100-year anniversary of brooklyn bridge (1983, new york city).

scholarly journals Polyphenols with Anti-Amyloid β Aggregation Show Potential Risk of Toxicity Via Pro-Oxidant Properties

2020 ◽  
Vol 21 (10) ◽  
pp. 3561 ◽  
Author(s):  
Hatasu Kobayashi ◽  
Mariko Murata ◽  
Shosuke Kawanishi ◽  
Shinji Oikawa
Keyword(s):  
Potential Risk ◽  
Deleterious Effect ◽  
Treatment Strategies ◽  
Amyloid Β ◽  
Chemical Compounds ◽  
Inhibitory Effect ◽  
Point Of View ◽  
Considerable Evidence ◽  
Naturally Occurring ◽  
Aβ Aggregation

Alzheimer’s disease (AD) is the most common form of dementia among older people. Amyloid β (Aβ) aggregation has been the focus for a therapeutic target for the treatment of AD. Naturally occurring polyphenols have an inhibitory effect on Aβ aggregation and have attracted a lot of attention for the development of treatment strategies which could mitigate the symptoms of AD. However, considerable evidence has shown that the pro-oxidant mechanisms of polyphenols could have a deleterious effect. Our group has established an assay system to evaluate the pro-oxidant characteristics of chemical compounds, based on their reactivity with DNA. In this review, we have summarized the anti-Aβ aggregation and pro-oxidant properties of polyphenols. These findings could contribute to understanding the mechanism underlying the potential risk of polyphenols. We would like to emphasize the importance of assessing the pro-oxidant properties of polyphenols from a safety point of view.

Sound Insulation Determination of Door

2014 ◽  
Vol 1057 ◽  
pp. 215-222 ◽  
Author(s):  
Dušan Dlhý ◽  
Peter Tomašovič
Keyword(s):  
Structural Complexity ◽  
Point Of View ◽  
Sound Insulation ◽  
Laboratory Measurements ◽  
Door Frame ◽  
Small Change ◽  
Sound Reduction ◽  
Reduction Index

The structural complexity of a door causes difficulties in the description of its behavior from an acoustical point of view. In many cases, even a small change can cause a big difference in its sound-isolating properties. To determine the acoustical quality of a door, it is important to perform laboratory measurements of the door structure and door frame, the gaps including. A mathematical analysis based on experimental measurements of the sound reduction index of several door constructions was used to determine the acoustical door categories. The equations for calculating the sound reduction index, which were introduced in this paper, should help in the design of a suitable door from an acoustical point of view.

scholarly journals Effect of aluminum concentration on growth and secondary metabolites production in three chemotypes of Cunila galioides Benth. medicinal plant

2011 ◽  
Vol 71 (4) ◽  
pp. 1003-1009 ◽  
Author(s):  
AJ. Mossi ◽  
GF. Pauletti ◽  
L. Rota ◽  
S. Echeverrigaray ◽  
IBI. Barros ◽  
...  
Keyword(s):  
Nutrient Solution ◽  
Dry Matter ◽  
Extraction Yield ◽  
Point Of View ◽  
Aluminum Concentration ◽  
Aluminum Stress ◽  
Naturally Occurring ◽  
Metabolites Production ◽  
Essential Oil Yield ◽  
Different Levels

Medicine plants play an important role in public health, especially in developing countries, and among them Cunila galioides Benth. is a naturally occurring medicinal and aromatic plant native from south Brazil. Flavonoids, present in significant amounts in some species of Cunila sp., possess several properties and its content may be affected by aluminum stress. In this context, the aim of this work was to assess the influence of different levels of aluminum in nutrient solution on the growth and content of essential oils and flavonoids in three chemotypes of Cunila galioides. The plant parameters evaluated were aerial dry matter, dry root matter, root length, root score, calcium and aluminum concentrations in the vegetable tissue, flavonoids content as well as essential oil yield and its major components concentration. Results showed that the addition of 30.0 mg.L--1 of Al3+ to the nutrient solution leads to a decrease of all agronomic parameters evaluated with losses in the cultivation yield for the greatest concentration studied. The André da Rocha population was found to be the most tolerant to aluminum while Bom Jardim da Serra was the most sensitive. The aluminum concentration did not influence the extraction yield as well as the content of major components in the oils. The concentration of flavonoids increased significantly for the populations tolerant to aluminum concentration in the nutrient solution, thus indicating a relationship between tolerance and flavonoids production, which may be an interesting characteristic from the medicinal point of view.

scholarly journals The protein structures that shape caspase activity, specificity, activation and inhibition

2004 ◽  
Vol 384 (2) ◽  
pp. 201-232 ◽  
Author(s):  
Pablo FUENTES-PRIOR ◽  
Guy S. SALVESEN
Keyword(s):  
Catalytic Mechanism ◽  
Protein Structures ◽  
Limited Proteolysis ◽  
Point Of View ◽  
Coagulation Cascade ◽  
Structural Basis ◽  
Apoptotic Pathway ◽  
Naturally Occurring ◽  
The Many ◽  
Apoptosis Regulation

The death morphology commonly known as apoptosis results from a post-translational pathway driven largely by specific limited proteolysis. In the last decade the structural basis for apoptosis regulation has moved from nothing to ‘quite good’, and we now know the fundamental structures of examples from the initiator phase, the pre-mitochondrial regulator phase, the executioner phase, inhibitors and their antagonists, and even the structures of some substrates. The field is as well advanced as the best known of proteolytic pathways, the coagulation cascade. Fundamentally new mechanisms in protease regulation have been disclosed. Structural evidence suggests that caspases have an unusual catalytic mechanism, and that they are activated by apparently unrelated events, depending on which position in the apoptotic pathway they occupy. Some naturally occurring caspase inhibitors have adopted classic inhibition strategies, but other have revealed completely novel mechanisms. All of the structural and mechanistic information can, and is, being applied to drive therapeutic strategies to combat overactivation of apoptosis in degenerative disease, and underactivation in neoplasia. We present a comprehensive review of the caspases, their regulators and inhibitors from a structural and mechanistic point of view, and with an aim to consolidate the many threads that define the rapid growth of this field.

scholarly journals Genistein does not Inhibit TGF-β1-Induced Conversion of Human Dermal Fibroblasts to Myofibroblasts

2021 ◽  
pp. 815-820
Author(s):  
M KAŇUCHOVÁ ◽  
L URBAN ◽  
N MELEGOVÁ ◽  
M ČOMA ◽  
B DVOŘÁNKOVÁ ◽  
...  
Keyword(s):  
Transforming Growth Factor Beta ◽  
Wound Repair ◽  
Transforming Growth Factor ◽  
Dermal Fibroblasts ◽  
Point Of View ◽  
Human Dermal Fibroblasts ◽  
Receptor Modulator ◽  
Naturally Occurring ◽  
Growth Factor Beta ◽  
Tgf Β1

Transforming growth factor beta 1 (TGF-β1) is a pro-fibrotic cytokine with a key role in wound repair and regeneration, including induction of fibroblast-to-myofibroblast transition. Genistein is a naturally occurring selective estrogen receptor modulator with promising anti-fibrotic properties. In the present study we aimed to investigate whether genistein modulates TGF-β1 (canonical and non-canonical) signaling in normal dermal fibroblasts at the protein level (Western blot and immunofluo-rescence). We demonstrated that TGF-β1 induces the myofibroblast-like phenotype in the studied fibroblast signaling via canonical (SMAD) and non-canonical (AKT, ERK1/2, ROCK) pathways. Genistein induced only ERK1/2 expression, whereas the combination of TGF-β1 and genistein attenuated the ERK1/2 and ROCK signaling. Of note, the other studied pathways remained almost unaffected. From this point of view, genistein does not impair conversion of normal fibroblasts to myofibroblast-like cells.

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