scholarly journals THE PERIODIC TABLE OF THE ELEMENTS AND THE ASSOCIATED MINERALS: URANIUM

2008 ◽  
Vol 16 (16) ◽  
pp. 59-82
Author(s):  
Paulo Cesar Pereira das Neves ◽  
Lavinel G. Ionescu
Keyword(s):  
Soil Water ◽  
Periodic Table ◽  
White Metal ◽  
Naturally Occurring ◽  
Low Concentrations ◽  
Actinide Series ◽  
Uranium Minerals

Uranium is silvery-white metal of the actinide series. It is the heaviest of naturally occurring elements and it is found in low concentrations in soil, water and rocks. Uranium is relatively reactive and combines with oxygen, sulfur, chlorine, fluorine, phosphorus, bromine and other elements. This article describes some of the properties and uses of uranium and presents a synopsis of the two hundred and four (204) uranium minerals known at the present time.

scholarly journals Evaluating the impact of exposure to environmental contaminants on human health

1996 ◽  
Vol 42 (8) ◽  
pp. 1345-1349 ◽  
Author(s):  
J B Silkworth ◽  
J F Brown
Keyword(s):  
Chemical Substances ◽  
The Public ◽  
Aromatic Hydrocarbon Receptor ◽  
Naturally Occurring ◽  
Synthetic Chemicals ◽  
Low Concentrations ◽  
Polycyclic Aromatic ◽  
Coplanar Polychlorinated Biphenyls ◽  
Proportional Contribution ◽  
The Impact

Abstract Humans are exposed daily to low concentrations of many different chemical substances, natural and some man-made. Although many of these substances can be toxic at high levels, typical exposures are far below the effect levels. The responses produced by man-made aromatic hydrocarbon receptor agonists, such as dioxins, polychlorinated dibenzofurans, coplanar polychlorinated biphenyls, and polycyclic aromatic hydrocarbons, are also produced, often to greater extents [corrected], by naturally occurring constituents of fried meat, cabbage, broccoli, cauliflower, cocoa, and curry. Our society seems to be concerned about the health risks associated only with the synthetic chemicals, regardless of their proportional contribution to the total agonist activity, and regulates on the basis of such concerns. It would be more protective of the public health to determine acceptable concentrations for each type of response, regardless of the origin of the inducing agent, and issue advisories or regulations accordingly.

The Seven Last Infra-Uranium Elements to Be Discovered

2019 ◽  
Author(s):  
Eric Scerri
Keyword(s):  
Periodic Table ◽  
Atomic Weight ◽  
Weak Acid ◽  
Ray Method ◽  
Natural Sources ◽  
Transuranium Elements ◽  
X Ray ◽  
Naturally Occurring ◽  
Missing Element

The term “infra-uranium,” meaning before uranium, is one that I have proposed by contrast to the better-known term transuranium elements that are discussed in the following chapter. The present chapter concerns the last seven elements that formed the missing gaps in the old periodic table that ended with the element uranium. After Moseley developed his X-ray method, it became clear that there were just seven elements yet to be isolated among the 92 naturally occurring elements or hydrogen (#1) to uranium (#92). This apparent simplicity is somewhat spoiled by the fact that, as it turned out, some of these seven elements were first isolated from natural sources following their being artificially created, but this raises more issues that are best left to the next chapter of this book. The fact remains that five of these seven elements are radioactive, the two exceptions being hafnium and rhenium, the second and third of them to be isolated. The first of the seven final infra-uranium elements to be discovered was protactinium, and it was one of the lesser-known predictions made by Mendeleev. In his famous 1896 paper, Mendeleev indicated incorrect values for both thorium (118) and uranium (116). (See figure 1.6.) A couple of years later, he corrected both of these values and showed a missing element between thorium and uranium (figure 4.4). In doing so, Mendeleev added the following paragraph, in which he made some specific predictions. . . . Between thorium and uranium in this series we can further expect an element with an atomic weight of about 235. This element should form a highest oxide R2O5, like Nb and Ta to which it should be analogous. Perhaps in the minerals which contain these elements a certain amount of weak acid formed from this metal will also be found.. . . The modern atomic weight for eka-tantalum or protactinium is 229.2. The apparent inaccuracy in Mendeleev’s prediction is not too surprising, however, since he never knew that protactinium is a member of only four “pair reversals” in the entire periodic table.

scholarly journals Glucosinolate Content in Brassica Genetic Resources and Their Distribution Pattern within and between Inner, Middle, and Outer Leaves

Plants ◽  
2020 ◽  
Vol 9 (11) ◽  
pp. 1421
Author(s):  
Ju-Hee Rhee ◽  
Susanna Choi ◽  
Jae-Eun Lee ◽  
On-Sook Hur ◽  
Na-Young Ro ◽  
...  
Keyword(s):  
Genetic Resources ◽  
Defense Mechanism ◽  
Multiple Reaction Monitoring ◽  
Principal Component ◽  
Brassica Species ◽  
Glucosinolate Content ◽  
Proximal Half ◽  
Naturally Occurring ◽  
Low Concentrations ◽  
Entire Dataset

Glucosinolates (GSLs) are sulfur-containing secondary metabolites naturally occurring in Brassica species. The purpose of this study was to identify the GSLs, determine their content, and study their accumulation patterns within and between leaves of kimchi cabbage (Brassica rapa L.) cultivars. GSLs were analyzed using UPLC-MS/MS in negative electron-spray ionization (ESI−) and multiple reaction monitoring (MRM) mode. The total GSL content determined in this study ranged from 621.15 to 42434.21 μmolkg−1 DW. Aliphatic GSLs predominated, representing from 4.44% to 96.20% of the total GSL content among the entire samples. Glucobrassicanapin (GBN) contributed the greatest proportion while other GSLs such as glucoerucin (ERU) and glucotropaeolin (TRO) were found in relatively low concentrations. Principal component analysis (PCA) yielded three principal components (PCs) with eigenvalues ≥ 1, altogether representing 74.83% of the total variation across the entire dataset. Three kimchi cabbage (S/No. 20, 4, and 2), one leaf mustard (S/No. 26), and one turnip (S/No. 8) genetic resources were well distinguished from other samples. The GSL content varied significantly among the different positions (outer, middle, and inner) of the leaves and sections (top, middle, bottom, green/red, and white) within the leaves. In most of the samples, higher GSL content was observed in the proximal half and white sections and the middle layers of the leaves. GSLs are regarded as allelochemicals; hence, the data related to the patterns of GSLs within the leaf and between leaves at a different position could be useful to understand the defense mechanism of Brassica plants. The observed variability could be useful for breeders to develop Brassica cultivars with high GSL content or specific profiles of GSLs.

scholarly journals Identification of Immune Regulatory Genes in Apis mellifera through Caffeine Treatment

Insects ◽  
2020 ◽  
Vol 11 (8) ◽  
pp. 516 ◽  
Author(s):  
Yun-Heng Lu ◽  
Carol-P Wu ◽  
Cheng-Kang Tang ◽  
Yu-Hsien Lin ◽  
Houda Ouns Maaroufi ◽  
...  
Keyword(s):  
Expression Profiles ◽  
Insect Immunity ◽  
Protective Measure ◽  
Valuable Insight ◽  
Deformed Wing Virus ◽  
Naturally Occurring ◽  
Copy Numbers ◽  
Expression Of Genes ◽  
Low Concentrations ◽  
Pharmacologically Active

Plants and pollinators are mutually beneficial: plants provide nectar as a food source and in return their pollen is disseminated by pollinators such as honeybees. Some plants secrete chemicals to deter herbivores as a protective measure, among which is caffeine, a naturally occurring, bitter tasting, and pharmacologically active secondary compound. It can be found in low concentrations in the nectars of some plants and as such, when pollinators consume nectar, they also take in small amounts of caffeine. Whilst caffeine has been indicated as an antioxidant in both mammals and insects, the effect on insect immunity is unclear. In the present study, honeybees were treated with caffeine and the expression profiles of genes involved in immune responses were measured to evaluate the influence of caffeine on immunity. In addition, honeybees were infected with deformed wing virus (DWV) to study how caffeine affects their response against pathogens. Our results showed that caffeine can increase the expression of genes involved in immunity and reduce virus copy numbers, indicating that it has the potential to help honeybees fight against viral infection. The present study provides a valuable insight into the mechanism by which honeybees react to biotic stress and how caffeine can serve as a positive contributor, thus having a potential application in beekeeping.

Water Shedding Properties of Oil Impregnated Hydrophobic Soils

2020 ◽  
Author(s):  
Rebecca McCerery ◽  
John Woodward ◽  
Glen McHale ◽  
Kate Winter
Keyword(s):  
Soil Water ◽  
Silicone Oil ◽  
Water Repellency ◽  
Contact Angles ◽  
Water Infiltration ◽  
Natural Soil ◽  
Particle Sizes ◽  
Soil Water Repellency ◽  
Water Contact ◽  
Naturally Occurring

<p>Hydrophobic soils and sediments have gained significant interest in soil science due to negatively influencing biomass production and as drivers of landslides and enhanced erosion. Whilst natural and fire-induced soil water repellency have been studied, little work has considered how the sediment-water interaction with naturally occurring hydrophobic sediments might change in the presence of oil. Recent advances in materials physics have shown bio-inspired slippery liquid infused porous surfaces (SLIPS) and lubricant impregnated surfaces (LIS) can produce super slippery surfaces with excellent water shedding properties. Here we apply this new understanding to the physics of soil water repellency and address how the presence of oil, whether from contamination or otherwise, might influence water infiltration. We hypothesise that oil impregnating a hydrophobic soil may create stable oil coatings and/or layers that create soil surfaces resistant to water infiltration and with enhanced run-off of water. Using monolayers of sand, silt and clay particles treated with a commercial hydrophobising agent and silicone oil, we created model (oil-free) hydrophobic and oil impregnated hydrophobic soils. Static water contact angles and droplet sliding angles were used to classify their degree of hydrophobicity and ability to shed water. Our results show that in the absence of oil, model hydrophobic soil surfaces with particle sizes below 63μm are superhydrophobic with water droplet contact angles above 150 degrees. In the presence of oil, we observed a sediment-based SLIP/LI surface on particle sizes below 63μm with water contact angles of 90 degrees and droplet sliding angles of below 5 degrees. We also achieved reduced sliding angles compared to the oil-free surfaces, and a conformal layer of oil on all particle sizes. These results support our hypothesis that SLIPS/LIS may occur in natural soil systems. These results have implications for soil water repellency, oil clean up from soil and for processes occurring in other sedimentary environments caused by both naturally occurring and anthropogenic contamination of oils.</p>

scholarly journals Genetically Modified Vibrio harveyiStrains as Potential Bioindicators of Mutagenic Pollution of Marine Environments

2000 ◽  
Vol 66 (2) ◽  
pp. 599-605 ◽  
Author(s):  
Agata Czyz˙ ◽  
Jacek Jasiecki ◽  
Adam Bogdan ◽  
Hanna Szpilewska ◽  
Grzegorz We˛grzyn
Keyword(s):  
Marine Bacterium ◽  
Genetically Modified ◽  
Marine Environments ◽  
Simple Method ◽  
Naturally Occurring ◽  
Low Concentrations ◽  
Serovar Typhimurium ◽  
Wild Type Counterpart ◽  
Mutagenic Pollution ◽  
Selection Of

ABSTRACT For biodetection of mutagenic pollution of marine environments, an organism naturally occurring in these habitats should be used. We found that marine bacterium Vibrio harveyi may be an appropriate bioindicator of mutagenic pollution. For positive selection of mutants, we developed a simple method for isolation of V. harveyimutants resistant to neomycin. We constructed genetically modifiedV. harveyi strains that produce significantly more neomycin-resistant mutants upon treatment with low concentrations of mutagens than the wild-type counterpart. The sensitivity of the mutagenicity test with the V. harveyi strains is at least comparable to (if not higher than) that of the commonly used Ames test, which uses Salmonella enterica serovar Typhimurium strains. Therefore, we consider that the V. harveyi strains described in this report could be used as potential bioindicators of mutagenic pollution of marine environments.

Engineering oxidative stability in human hemoglobin based on the Hb providence (βK82D) mutation and genetic cross-linking

2017 ◽  
Vol 474 (24) ◽  
pp. 4171-4192 ◽  
Author(s):  
Michael Brad Strader ◽  
Rachel Bangle ◽  
Claire J. Parker Siburt ◽  
Cornelius L. Varnado ◽  
Jayashree Soman ◽  
...  
Keyword(s):  
Oxidative Degradation ◽  
Oxygen Affinity ◽  
Side Chain ◽  
Cross Linking ◽  
Critical Element ◽  
Low Oxygen ◽  
Naturally Occurring ◽  
Low Concentrations ◽  
Genetic Cross ◽  
Low Oxygen Affinity

Previous work suggested that hemoglobin (Hb) tetramer formation slows autoxidation and hemin loss and that the naturally occurring mutant, Hb Providence (HbProv; βK82D), is much more resistant to degradation by H2O2. We have examined systematically the effects of genetic cross-linking of Hb tetramers with and without the HbProv mutation on autoxidation, hemin loss, and reactions with H2O2, using native HbA and various wild-type recombinant Hbs as controls. Genetically cross-linked Hb Presbyterian (βN108K) was also examined as an example of a low oxygen affinity tetramer. Our conclusions are: (a) at low concentrations, all the cross-linked tetramers show smaller rates of autoxidation and hemin loss than HbA, which can dissociate into much less stable dimers and (b) the HbProv βK82D mutation confers more resistance to degradation by H2O2, by markedly inhibiting oxidation of the β93 cysteine side chain, particularly in cross-linked tetramers and even in the presence of the destabilizing Hb Presbyterian mutation. These results show that cross-linking and the βK82D mutation do enhance the resistance of Hb to oxidative degradation, a critical element in the design of a safe and effective oxygen therapeutic.

scholarly journals Repellence and attraction of Apis mellifera foragers by nectar alkaloids

2016 ◽  
Vol 47 (1) ◽  
pp. 14-17
Author(s):  
Z. Hroncová ◽  
J. Havlík ◽  
L. Stanková ◽  
S. Hájková ◽  
D. Titěra ◽  
...  
Keyword(s):  
Secondary Metabolites ◽  
Plant Secondary Metabolites ◽  
Taste Preference ◽  
Self Medication ◽  
Addictive Behaviour ◽  
Naturally Occurring ◽  
Low Concentrations ◽  
Floral Visitors ◽  
Honey Bee Foragers ◽  
Artificial Flowers

Abstract Plant secondary metabolites present naturally in nectar, such as alkaloids, may change the behavioural responses of floral visitors and affect pollination. Some studies have shown that nectar containing low concentrations of these secondary metabolites is preferred by honey bee foragers over pure nectar. However, it remains unclear whether this is caused by dependence or addictive behaviour, a simple taste preference, or by other conditions such as self-medication. In our choice experiment, free-flying bees were presented with artificial flowers holding 20% sucrose containing 0.5−50 μg ml−1 of one of the naturally occurring nectar alkaloids - caffeine, nicotine, senecionine, and gelsemine. Nectar uptake was determined by weighing each flower and comparing the weight to that of the control flower. Our experimental design minimized memorizing and marking; despite this, caffeine was significantly preferred at concentrations 0.5−2 μg ml−1 over control nectar; this preference was not observed for other alkaloids. All of the compounds tested were repellent at concentrations above 5 μg ml−1. We confirmed previous reports that bees exhibit a preference for caffeine, and hypothesize that this is not due only to addictive behaviour but is at least partially mediated by taste preference. We observed no significant preference for nicotine or any other alkaloid.

The Hanau Land Remediation and Soil Segregation Project

2003 ◽  
Author(s):  
Gerold G. Simon ◽  
Marina Sokcic-Kostic ◽  
Bernhard G. Christ
Keyword(s):  
Significant Proportion ◽  
Process Equipment ◽  
Specific Information ◽  
Building Structure ◽  
Soil Material ◽  
Naturally Occurring ◽  
Fuel Fabrication ◽  
Low Concentrations ◽  
System Components

Radioactively contaminated land and its remediation is a growing sector of the Nuclear Business. The contamination is often associated with both naturally occurring and man-made radionuclides. A significant proportion of the waste contains only small amounts or low concentrations of radionuclides, and therefore much of the remediated material can be considered to be for “free release”. It has often not been possible to get adequate specific information on these materials, so a monitoring system is needed for their classification and characterisation. At the former Fuel Fabrication Facility NUKEM-Old in Hanau, Germany, all process equipment and installations were dismantled, building structure surfaces have been decontaminated. After final measurements of building contamination, mainly applying in-situ gamma-spectrometry, and approval for “free release”, or for dumping the material, all buildings were demolished. Since then, an Automated Soil Segregation System is being successfully used for the segregation and measuring of the remaining 20.000 tonnes of radioactively contaminated, or at least suspicious soil material, building foundations and sewerage system components.

Antibiofilm activity of lactoferrin-derived synthetic peptides against Pseudomonas aeruginosa PAO1

2020 ◽  
Author(s):  
Gopal Ramamourthy ◽  
Hans J. Vogel
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Pathogenic Bacteria ◽  
Antibiofilm Activity ◽  
Bacterial Killing ◽  
Pseudomonas Aeruginosa Pao1 ◽  
Naturally Occurring ◽  
Low Concentrations ◽  
Bovine Lactoferricin ◽  
Antibiofilm Agents ◽  
Mix And Match

Many pathogenic bacteria can protect themselves from the effects of antibiotics and the host immune response system by forming biofilms. Eradication of bacterial biofilms typically requires much higher concentrations of antibiotics, than are normally needed to kill cultured planktonic cells, raising serious clinical concerns. In an attempt to try to prevent the formation of biofilms or to break up existing biofilms of pathogenic bacteria, herein we have used the standard crystal violet assay as well as the Calgary biofilm device, to test several lactoferrin- and lactoferricin-derived antimicrobial peptides for their antibiofilm activity against Pseudomonas aeruginosa PAO1. Our results reveal that the short bovine lactoferricin-derived RRWQWR-NH2 (20-25) hexapeptide has no activity against P. aeruginosa PAO1. Moreover, the longer human lactoferricin-derived peptide GRRRRSVQWCA (1-11) and the bovine lactoferrampin (268-284) peptide were also almost devoid of activity. However, several different ‘mix-and-match’ dimeric versions of the two lactoferricin-derived peptides proved quite effective at low concentrations in preventing the formation of biofilms, and in some cases, could even eradicate existing biofilm. Some of the longer lactoferricin-derived dimeric peptides acted through a bacterial killing mechanism, while others seemed to interfere in cellular signalling processes. Taken together, our results reveal that synthetic dimeric peptides made up of the short naturally-occurring human and bovine lactoferricin constructs, can be further developed as antibiofilm agents

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