scholarly journals Environmental magnetism: Application to cave sediments

2017 ◽  
Vol 47 (2) ◽  
pp. 892 ◽  
Author(s):  
E. Aidona ◽  
S. Pechlivanidou ◽  
Ch. Pennos
Keyword(s):  
Magnetic Susceptibility ◽  
Magnetic Measurements ◽  
Low Cost ◽  
Environmental Magnetism ◽  
Northern Greece ◽  
Cave Sediments ◽  
Wide Range ◽  
Sediment Records ◽  
Archaeological Artifacts

Environmental magnetism techniques allow a rapid, low cost and sensitive characterization of sediments and can be applied in a wide range of environments. More specific, magnetic properties can be successfully used to reconstruct paleoenvironmental and paleoclimatic conditions in rockshelter and cave sites. Cave sediments, imprint the environmental conditions at the Earth’s surface at the time of deposition since are well protected both at the interior and at the entrance of the cave systems. In addition, many cultural sequences and archaeological artifacts are well preserved in rockshelter and cave sediment records and can be effectively used for paleoenvironmental interpretations. In this study we present data from two different cave sites from Northern Greece. In the first cave (Maronia Cave) magnetic measurements were performed in two cores 80 and 90 cm, respectively, located inside the cave area. High values of magnetic susceptibility are directly linked with the human activity inside the cave, while lower values show deposition under infiltration and fluvial processes. In the second cave (Mikro Eptamilon Cave), magnetic susceptibility and frequency dependent magnetic susceptibility depicted from a sedimentary sequence with a thickness of 200 cm, located in the entrance of the cave. Results lead to conclusions concerning the velocity of the paleo-flow likely related to the paleoclimatic conditions that dominated the broader area.

scholarly journals Φυσικογεωγραφική, ιζηματολογική μελέτη και ανίχνευ-ση των μαγνητικών ιδιοτήτων των ιζημάτων του ‘Μικρού’ σπηλαίου των Επταμύλων Σερρών

2017 ◽  
Vol 44 ◽  
pp. 37
Author(s):  
Σ. Πεχλιβανίδου ◽  
E. Αηδονά ◽  
Κ. Βουβαλίδης ◽  
Χ. Πέννος ◽  
Κ. Αλμπανάκης
Keyword(s):  
Grain Size ◽  
Magnetic Susceptibility ◽  
Magnetic Measurements ◽  
Environmental Magnetism ◽  
Grain Size Analysis ◽  
Size Analysis ◽  
Sedimentary Sequence ◽  
Northern Greece ◽  
Depositional Processes ◽  
Clastic Sediments

In the area of Eptamili Village, located at the foothills of the southern-eastern part of Mount Menoikio (Serres Prefecture, Northern Greece) two underground karst cavities were revealed during the works of marble exploitation, named as ‘Mikro’ and ‘Megalo’ Cave of Eptamilon. At the entrance of the ‘Mikro’ Cave there is a naturally deposited sequence of clastic sediments alternating with chemical deposits with a thickness of ~2m, lying uncomfortably on the bedrock marbles. In order to investigate the depositional processes and conditions and to understand the palaeoenvironmental changes during the cave evolution, grain size analysis and magnetic measurements were conducted on sediment samples from the sedimentary sequence. Grain size analysis showed the presence of fine sandy beds alternating with silty and clayey layers. This structure correlates with the magnetic signature of the sediments and especially the magnetic susceptibility (xlf) and the frequency depended magnetic susceptibility (xfd), conducting conclusions concerning the palaeoclimatic conditions and the velocity of the flow during the time of deposition of the sedimentary sequence. This study suggest the use of environmental magnetism as an independent methodology in palaeoenvironmental studies.

An overview: characterization of natural fiber reinforced hybrid composites

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
M. Balasubramanian ◽  
Thozhuvur Govindaraman Loganathan ◽  
R. Srimath
Keyword(s):  
Natural Fiber ◽  
Hybrid Composites ◽  
Low Cost ◽  
Research Work ◽  
Tensile Modulus ◽  
Fiber Reinforced ◽  
Content Type ◽  
Specific Strength ◽  
Wide Range

Purpose The purpose of this study is to understand the behavior of hybrid bio-composites under varied applications. Design/methodology/approach Fabrication methods and material characterization of various hybrid bio-composites are analyzed by studying the tensile, impact, flexural and hardness of the same. The natural fiber is a manufactured group of assembly of big or short bundles of fiber to produce one or more layers of flat sheets. The natural fiber-reinforced composite materials offer a wide range of properties that are suitable for many engineering-related fields like aerospace, automotive areas. The main characteristics of natural fiber composites are durability, low cost, low weight, high specific strength and equally good mechanical properties. Findings The tensile properties like tensile strength and tensile modulus of flax/hemp/sisal/Coir/Palmyra fiber-reinforced composites are majorly dependent on the chemical treatment and catalyst usage with fiber. The flexural properties of flax/hemp/sisal/coir/Palmyra are greatly dependent on fiber orientation and fiber length. Impact properties of flax/hemp/sisal/coir/Palmyra are depended on the fiber content, composition and orientation of various fibers. Originality/value This study is a review of various research work done on the natural fiber bio-composites exhibiting the factors to be considered for specific load conditions.

Exploring Magnetic Properties as a Potential Pollution Proxy for Monitoring Levels and Bioaccessibility of Lead (Pb) in Playground Sand: a Preliminary Study  

2021 ◽  
Author(s):  
Anna Bourliva ◽  
Elina Aidona ◽  
Carla Patinha
Keyword(s):  
Magnetic Susceptibility ◽  
Magnetic Measurements ◽  
The European Union ◽  
Soil Dust ◽  
Case Scenario ◽  
Northern Greece ◽  
Development Education ◽  
Worst Case ◽  
Magnetic Phases ◽  
Social Fund

<p>The need to control soil/dust quality in recreation sites of urban agglomerations, especially in those where children are exposed, has been extensively highlighted. Particularly, in children’s play sites it is imperative to quantify the levels of potential harmful elements (PHEs) in soils and dusts. Particularly, lead (Pb) is an element of concern since exposure of children to Pb and the consequently elevated blood Pb levels are linked to severe behavioral disorders and reductions of intellectual function. On the other hand, the use of magnetic methods is proposed as a quick and inexpensive first step in assessing soil/dust pollution by providing qualitative data on its degree and extent. The aim of the present study was to perform magnetic measurements in order to find a relationship between levels and bioaccessibility of Pb in playground sands and sand-bound iron-bearing magnetic phases. For this reason, composite sand samples were collected within the top layer at 37 public playgrounds in the broader area of the city of Thessaloniki, Northern Greece. Sampling conducted from 2-5 spots of the playground not covered by the treetops, nor at the edge of the playground or near to vegetation or urban furniture. The mass specific magnetic susceptibility (χ<sub>lf</sub>) of the playground sands exhibited a range of 51-248.7 x 10<sup>-8</sup> m<sup>3</sup> kg<sup>-1</sup> with a median of 149.8 x10<sup>-8</sup> m<sup>3</sup> kg<sup>-1</sup> indicating a notable amount of sand-bound Fe-bearing magnetic phases. The frequency dependent magnetic susceptibility (χ<sub>fd</sub>) varied among 0.11 to 7.73% with only limited sand samples exhibiting values >5%, suggesting the lack of super paramagnetic magnetite grains within the majority of the studied samples. The total Pb concentrations in playground sands ranged from 18.6 to 46.7 mg kg<sup>-1</sup> with a median of  28.7 mg kg<sup>-1 </sup>and lies within the ranges reported by other researchers. Despite the insignificant differences observed on Pb contents among a sub-set of 12 sands with elevated χ<sub>lf</sub> values (mean Pb 31.3 mg kg<sup>-1</sup> , χ<sub>lf</sub> > 175 x 10<sup>-8</sup> m<sup>3</sup> kg<sup>-1</sup> ) and the rest of the samples (mean Pb 29.7 mg kg<sup>-1</sup>), a moderate correlation coefficient (r=0.685, p<0.05) was recorded between χ<sub>lf</sub> and Pb in the enhanced magnetized sub-set underscoring a probable linkage with the ferrimagnetic particles of playground sand. Bioaccessible Pb concentrations (gastric phase) ranged from 5.73 to 20.7 mg kg<sup>-1</sup> with 22-44% of Pb being in  bioaccessible form in the playground sands. Different lead intake scenarios (based on bioaccessible Pb) underscored no health risk for children through sand ingestion with the exception of a worst case scenario of pica behaviour (intake 20g/d).</p><p><strong>Acknowledgements:</strong> This research is co-financed by Greece and the European Union (European Social Fund- ESF) through the Operational Programme «Human Resources Development, Education and Lifelong Learning» in the context of the project “Reinforcement of Postdoctoral Researchers - 2<sup>nd</sup> Cycle” (MIS-5033021), implemented by the State Scholarships Foundation (ΙΚΥ).</p>

Purification and Characterization of Thermostable α-Amylase from Soil Bacterium Bacillus sp.

2021 ◽  
Vol 28 ◽  
Author(s):  
Barış Enez
Keyword(s):  
Metal Ions ◽  
Amylase Activity ◽  
Low Cost ◽  
Sodium Dodecyl ◽  
Tween 20 ◽  
Bacillus Sp ◽  
Wide Range ◽  
Bacterium Bacillus ◽  
Triton X

Background: Amylases are used in several industrial and biotechnological sectors, including those producing textiles, detergents, paper and bakery products. Objective: This study aimed to purify an industrially important α-amylase from Bacillus sp. For this purpose, a single and rapid α-amylase purification was performed using the starch affinity method. Methods: Characterization of the purified enzyme was determined by investigating temperature, pH stability, detergents, and metal ions. Results: The purification coefficient of 29.8-fold with a yield of 9.2% was found. The molecular weight of the purified α-amylase was determined to be 53 kDa by SDS-PAGE, and thermostability was confirmed with 100% activity at 30ºC and 40ºC after 1 h. The purified enzyme was stable over a wide range of pH values, with optimum activity at pH 6.0, 7.0 and 8.0 after 2 h. The study also investigated the effects of the metal ions and detergents on the purified amylase and found that Mg2+ and Ca2+ ions were the activators of the enzyme, while Zn2+, Co2+ and Na+ ions decreased the activity. Furthermore, Hg2+ indicated complete inhibition of amylase activity. The detergents Triton X-100 and Tween 20 increased the α-amylase activity, while sodium dodecyl sulfate inhibited the activity. Conclusion: The purified α-amylase obtained from Bacillus sp. is considered to be environmentally friendly, can be processed in a short time, and has a low cost.

scholarly journals Unidirectional Magnetic Anisotropy in Dense Vertically-Standing Arrays of Passivated Nickel Nanotubes

Nanomaterials ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 2444
Author(s):  
Claudiu Locovei ◽  
Nicolae Filipoiu ◽  
Andrei Kuncser ◽  
Anda-Elena Stanciu ◽  
Ştefan Antohe ◽  
...  
Keyword(s):  
Magnetic Measurements ◽  
Low Cost ◽  
Magnetic Behavior ◽  
Fine Tuning ◽  
Geometrical Parameters ◽  
Micromagnetic Simulations ◽  
Electrochemical Growth ◽  
Si Substrates ◽  
Unidirectional Anisotropy

We report the facile and low-cost preparation as well as detailed characterization of dense arrays of passivated ferromagnetic nickel (Ni) nanotubes (NTs) vertically-supported onto solid Au-coated Si substrates. The proposed fabrication method relies on electrochemical synthesis within the nanopores of a supported anodic aluminum oxide (AAO) template and allows for fine tuning of the NTs ferromagnetic walls just by changing the cathodic reduction potential during the nanostructures’ electrochemical growth. Subsequently, the experimental platform allowed further passivation of the Ni NTs with the formation of ultra-thin antiferromagnetic layers of nickel oxide (NiO). Using adequately adapted magnetic measurements, we afterwards demonstrated that the thickness of the NT walls and of the thin antiferromagneticNiO layer, strongly influences the magnetic behavior of the dense array of exchange-coupled Ni/NiO NTs. The specific magnetic properties of these hybrid ferromagnetic/antiferromagnetic nanosystems were then correlated with the morpho-structural and geometrical parameters of the NTs, as well as ultimately strengthened by additionally-implemented micromagnetic simulations. The effect of the unidirectional anisotropy strongly amplified by the cylindrical geometry of the ferromagnetic/antiferromagnetic interfaces has been investigated with the magnetic field applied both parallel and perpendicular to the NTs axis.

scholarly journals Low-Cost Synthesis and Characterization of Silver Nanoparticles for Diverse Sensing Application

2019 ◽  
Vol 9 (2) ◽  
pp. 3915-3917
Author(s):  
S. Akhtar ◽  
Z. Farid ◽  
H. Ahmed ◽  
S. A. Khan ◽  
Z. N. Khan
Keyword(s):  
Silver Nanoparticles ◽  
Chemical Reduction ◽  
Low Cost ◽  
Industrial Applications ◽  
X Ray Diffraction ◽  
Ag Nps ◽  
X Ray ◽  
Wide Range ◽  
Range Of Functions

Silver (Ag) nanoparticles (NPs) are synthesized and characterized by a low-cost chemical reduction method. Silver nanoparticles (Ag NPs) have pre-occupied the consideration of the scientific community due to their wide range of functions, utility and industrial applications, particularly in the fields of sensing technologies and medicine (particularly their efficiency against microbes, the ability of healing the wound and anti-inflammatory properties). Ag NPs are synthesized by a low-cost fabrication method. X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray diffraction (EDX) and photometry techniques are used in this work to identify their nature and potentiality for diverse applications in sensing technologies.

scholarly journals Graphene for the Building of Electroanalytical Enzyme-Based Biosensors. Application to the Inhibitory Detection of Emerging Pollutants

Nanomaterials ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 2094 ◽  
Author(s):  
Marta Bonet-San-Emeterio ◽  
Noelia Felipe Montiel ◽  
Manel del Valle
Keyword(s):  
Graphene Oxide ◽  
Benzoic Acid ◽  
Low Cost ◽  
Reduced Graphene ◽  
Maximum Inhibition ◽  
Wide Range ◽  
Carboxylic Groups ◽  
Enzymatic Biosensor ◽  
Laccase Enzyme

Graphene and its derivates offer a wide range of possibilities in the electroanalysis field, mainly owing to their biocompatibility, low-cost, and easy tuning. This work reports the development of an enzymatic biosensor using reduced graphene oxide (RGO) as a key nanomaterial for the detection of contaminants of emerging concern (CECs). RGO was obtained from the electrochemical reduction of graphene oxide (GO), an intermediate previously synthesized in the laboratory by a wet chemistry top-down approach. The extensive characterization of this material was carried out to evaluate its proper inclusion in the biosensor arrangement. The results demonstrated the presence of GO or RGO and their correct integration on the sensor surface. The detection of CECs was carried out by modifying the graphene platform with a laccase enzyme, turning the sensor into a more selective and sensitive device. Laccase was linked covalently to RGO using the remaining carboxylic groups of the reduction step and the carbodiimide reaction. After the calibration and characterization of the biosensor versus catechol, a standard laccase substrate, EDTA and benzoic acid were detected satisfactorily as inhibiting agents of the enzyme catalysis obtaining inhibition constants for EDTA and benzoic acid of 25 and 17 mmol·L−1, respectively, and a maximum inhibition percentage of the 25% for the EDTA and 60% for the benzoic acid.

scholarly journals Expanding the toolbox for Synechocystis sp. PCC 6803: validation of replicative vectors and characterization of a novel set of promoters

2018 ◽  
Vol 3 (1) ◽  
Author(s):  
Eunice A Ferreira ◽  
Catarina C Pacheco ◽  
Filipe Pinto ◽  
José Pereira ◽  
Pedro Lamosa ◽  
...  
Keyword(s):  
Low Cost ◽  
Carbon Sources ◽  
Proof Of Concept ◽  
Gene Encoding ◽  
Metabolic Plasticity ◽  
Cell Factories ◽  
Wide Range ◽  
Synechocystis Sp ◽  
Pcc 6803

Abstract Cyanobacteria are promising ‘low-cost’ cell factories since they have minimal nutritional requirements, high metabolic plasticity and can use sunlight and CO2 as energy and carbon sources. The unicellular Synechocystis sp. PCC 6803, already considered the ‘green’ Escherichia coli, is the best studied cyanobacterium but to be used as an efficient and robust photoautotrophic chassis it requires a customized and well-characterized toolbox. In this context, we evaluated the possibility of using three self-replicative vectors from the Standard European Vector Architecture (SEVA) repository to transform Synechocystis. Our results demonstrated that the presence of the plasmid does not lead to an evident phenotype or hindered Synechocystis growth, being the vast majority of the cells able to retain the replicative plasmid even in the absence of selective pressure. In addition, a set of heterologous and redesigned promoters were characterized exhibiting a wide range of activities compared to the reference PrnpB, three of which could be efficiently repressed. As a proof-of-concept, from the expanded toolbox, one promoter was selected and assembled with the ggpS gene [encoding one of the proteins involved in the synthesis of the native compatible solute glucosylglycerol (GG)] and the synthetic device was introduced into Synechocystis using one of the SEVA plasmids. The presence of this device restored the production of the GG in a ggpS deficient mutant validating the functionality of the tools/device developed in this study.

scholarly journals Developing Nanodisc-ID for label-free characterizations of membrane proteins

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Huan Bao
Keyword(s):  
Membrane Proteins ◽  
Protein Interactions ◽  
Gel Electrophoresis ◽  
Low Cost ◽  
Label Free ◽  
Protein Protein Interactions ◽  
Peripheral Membrane Proteins ◽  
Wide Range ◽  
Neural Transmission

AbstractMembrane proteins (MPs) influence all aspects of life, such as tumorigenesis, immune response, and neural transmission. However, characterization of MPs is challenging, as it often needs highly specialized techniques inaccessible to many labs. We herein introduce nanodisc-ID that enables quantitative analysis of membrane proteins using a gel electrophoresis readout. By leveraging the power of nanodiscs and proximity labeling, nanodisc-ID serves both as scaffolds for encasing biochemical reactions and as sensitive reagents for detecting membrane protein-lipid and protein-protein interactions. We demonstrate this label-free and low-cost tool by characterizing a wide range of integral and peripheral membrane proteins from prokaryotes and eukaryotes.

Polymer Chemistry

2004 ◽  
Keyword(s):  
Conducting Polymers ◽  
Liquid Crystalline ◽  
Polymer Chemistry ◽  
Chain Growth ◽  
Crystalline Polymers ◽  
Wide Range ◽  
Cyclic Oligomers ◽  
Step Growth

Polymer Chemistry: A Practical Approach in Chemistry has been designed for both chemists working in and new to the area of polymer synthesis. It contains detailed instructions for preparation of a wide-range of polymers by a wide variety of different techniques, and describes how this synthetic methodology can be applied to the development of new materials. It includes details of well-established techniques, e.g. chain-growth or step-growth processes together with more up-to-date examples using methods such as atom-transfer radical polymerization. Less well-known procedures are also included, e.g. electrochemical synthesis of conducting polymers and the preparation of liquid crystalline elastomers with highly ordered structures. Other topics covered include general polymerization methodology, controlled/"living" polymerization methods, the formation of cyclic oligomers during step-growth polymerization, the synthesis of conducting polymers based on heterocyclic compounds, dendrimers, the preparation of imprinted polymers and liquid crystalline polymers. The main bulk of the text is preceded by an introductory chapter detailing some of the techniques available to the scientist for the characterization of polymers, both in terms of their chemical composition and in terms of their properties as materials. The book is intended not only for the specialist in polymer chemistry, but also for the organic chemist with little experience who requires a practical introduction to the field.

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