scholarly journals Wet-chemical extractions to characterise pedogenic Al and Fe species – a critical review

Soil Research ◽  
2019 ◽  
Vol 57 (1) ◽  
pp. 1 ◽  
Author(s):  
Thilo Rennert
Keyword(s):  
Standard Procedure ◽  
Total Content ◽  
Soil Classification ◽  
Extraction Methods ◽  
Chemical Extraction ◽  
Spectroscopic Techniques ◽  
Practical Applications ◽  
Fe Species ◽  
Chemical Extractions ◽  
Wet Chemical

Wet-chemical extraction of soil is a standard procedure to characterise pedogenic aluminium (Al) and iron (Fe) species, especially oxides, allophanic minerals and metal–organic associations. This article critically reviews the suitability of commonly used extractants (e.g. dithionite, oxalate and pyrophosphate) and the potentials and restrictions in their use for species identification and in soil classification. None of the commonly used extractants is completely selective and quantitative. The degree of completeness differs between the extractants and depends on soil composition. Dithionite-based methods provide a ‘pseudo-total’ content of pedogenic Fe oxides, as they are not always completely dissolved. Oxalate may attack further non-target species, releasing additional Al and Fe. Therefore, the extraction of Al and Fe exclusively from poorly crystalline species is not always guaranteed. As a consequence of dispersion of aggregates, pyrophosphate solubilises both mineral particles and metals from organic associations. Thus, quantification of species based on these extractions and their implementation in pedogenic thresholds may be questionable. Alternative extractants such as citrate–ascorbate and dithionite–citrate–oxalate could be used in addition, as applicable and reliable wet-chemical extractions will be still demanded for research and practical applications. The examination of the effectiveness and selectivity of wet-chemical extraction methods by spectroscopic techniques is recommended.

Characterization of intergranular cuprous oxide in polycrystalline YBa2Cu3O7-x

1988 ◽  
Vol 46 ◽  
pp. 880-881
Author(s):  
Bradley L. Thiel ◽  
Chan Han R. P. ◽  
Kurosky L. C. Hutter ◽  
I. A. Aksay ◽  
Mehmet Sarikaya
Keyword(s):  
Grain Boundary ◽  
Cuprous Oxide ◽  
Room Temperature ◽  
Boundary Phase ◽  
Spectroscopic Techniques ◽  
Transition Width ◽  
Practical Applications ◽  
Thin Foils ◽  
Superconducting Oxides

The identification of extraneous phases is important in understanding of high Tc superconducting oxides. The spectroscopic techniques commonly used in determining the origin of superconductivity (such as RAMAN, XPS, AES, and EXAFS) are surface-sensitive. Hence a grain boundary phase several nanometers thick could produce irrelevant spectroscopic results and cause erroneous conclusions. The intergranular phases present a major technological consideration for practical applications. In this communication we report the identification of a Cu2O grain boundary phase which forms during the sintering of YBa2Cu3O7-x (1:2:3 compound).Samples are prepared using a mixture of Y2O3. CuO, and BaO2 powders dispersed in ethanol for complete mixing. The pellets pressed at 20,000 psi are heated to 950°C at a rate of 5°C per min, held for 1 hr, and cooled at 1°C per min to room temperature. The samples show a Tc of 91K with a transition width of 2K. In order to prevent damage, a low temperature stage is used in milling to prepare thin foils which are then observed, using a liquid nitrogen holder, in a Philips 430T at 300 kV.

Metal and phosphate speciation during anaerobic digestion of phosphorus rich sludge

1997 ◽  
Vol 36 (6-7) ◽  
pp. 191-200 ◽  
Author(s):  
C. M. Carliell ◽  
A. D. Wheatley
Keyword(s):  
Anaerobic Digestion ◽  
Metal Speciation ◽  
Extraction Methods ◽  
Phosphate Removal ◽  
Metal Species ◽  
Chemical Extraction ◽  
Inorganic P ◽  
Similar Work ◽  
Extractable P ◽  
Phosphate Speciation

Chemical extraction methods are used to investigate metal and phosphate speciation during anaerobic digestion of phosphorus-rich sludge. Tests were performed using model compounds to evaluate the efficacy of the reagents in the extraction sequences and these results compared with similar work by other researchers. The metal speciation method was found to be suitable for identifying shifts in metal distribution but was unrepresentative of actual metal species. The phosphate speciation method did give adequate separation of the phosphate compounds tested. Full-scale digesters treating chemical and biological phosphate removal (CPR and BPR) sludge were analysed according to the methods developed. Results show that digestion of CPR sludge did not increase the soluble P concentration in the digester and that most of the precipitated phosphorus appeared to be retained in the sludge as inorganic P. The digester treating BPR sludge showed increased soluble and water-extractable P, in comparison to the control digester. Trace metal speciation profiles were found to be affected by addition of CPR sludge.

scholarly journals Incubation methods for assessing mineralizable nitrogen in soils under sugarcane

2013 ◽  
Vol 37 (2) ◽  
pp. 450-461 ◽  
Author(s):  
Eduardo Mariano ◽  
Paulo Cesar Ocheuze Trivelin ◽  
José Marcos Leite ◽  
Michele Xavier Vieira Megda ◽  
Rafael Otto ◽  
...  
Keyword(s):  
N Mineralization ◽  
Standard Technique ◽  
Extraction Methods ◽  
N Fertilization ◽  
Chemical Extraction ◽  
Net N Mineralization ◽  
Anaerobic Incubation ◽  
Aerobic Incubation ◽  
Mineralizable N

Considering nitrogen mineralization (N) of soil organic matter is a key aspect for the efficient management of N fertilizers in agricultural systems. Long-term aerobic incubation is the standard technique for calibrating the chemical extraction methods used to estimate the potentially mineralizable N in soil. However, the technique is laborious, expensive and time-consuming. In this context, the aims of this study were to determine the amount of soil mineralizable N in the 0-60 cm layer and to evaluate the use of short-term anaerobic incubation instead of long-term aerobic incubation for the estimation of net N mineralization rates in soils under sugarcane. Five soils from areas without previous N fertilization were used in the layers 0-20, 20-40 and 40-60 cm. Soil samples were aerobically incubated at 35 ºC for 32 weeks or anaerobically incubated (waterlogged) at 40 ºC for seven days to determine the net soil N mineralization. The sand, silt and clay contents were highly correlated with the indexes used for predicting mineralizable N. The 0-40 cm layer was the best sampling depth for the estimation of soil mineralizable N, while in the 40-60 cm layer net N mineralization was low in both incubation procedures. Anaerobic incubation provided reliable estimates of mineralizable N in the soil that correlated well with the indexes obtained using aerobic incubation. The inclusion of the pre-existing NH4+-N content improved the reliability of the estimate of mineralizable N obtained using anaerobic incubation.

scholarly journals Graphene oxide chemically decorated with hybrid Ag-Ru/chitosan nanoparticles: fabrication and properties

2015 ◽  
Author(s):  
Murugan Veerapandian ◽  
Suresh Neethirajan
Keyword(s):  
Graphene Oxide ◽  
Chitosan Nanoparticles ◽  
Hybrid Nanoparticles ◽  
Spectroscopic Techniques ◽  
Wet Chemical ◽  
Amine Groups ◽  
Oxygenated Functional Groups ◽  
Coordination Reaction

Hybridization of distinct materials into a single nanoplatform is relevant to advance material’s properties for functional application such as biosensor platform. We report the synthesis and characterization of nanosheets of graphene oxide decorated with hybrid nanoparticles of silver-ruthenium bipyridine complex (Ag@[Ru(bpy)3]2+) core and chitosan shell. Hybrid nanoparticles were first obtained through a sequential wet-chemical approach using in situ reduction, electrostatic and coordination reaction. Oxygenated functional groups of graphene oxide and abundant amine groups of chitosan layer on the surface of hybrid nanoparticles allowed the functionalization reaction. Changes in intrinsic optical, chemical and structural properties of graphene oxide due to hybrid nanoparticles were studied in depth using spectroscopic techniques and an electron microscope. Electrodes modified with nanosheets of graphene oxide-hybrid nanoparticles retain the biocompatibility and displayed an amplified redox property suitable for a broad range of sensing studies.

scholarly journals A STRATEGY FOR DETERMINING THE CHEMICAL COMPOSITION OF RICE STRAW

2020 ◽  
Vol 54 (9-10) ◽  
pp. 983-991
Author(s):  
MAHESHANI P. A. NANAYAKKARA ◽  
WALAGEDARA G.A. PABASARA ◽  
ADIKARI M.P.B. SAMARASEKARA ◽  
DON A.S. AMARASINGHE ◽  
LALEEN KARUNANAYAKE
Keyword(s):  
Rice Straw ◽  
Research Work ◽  
Extraction Process ◽  
Chemical Extraction ◽  
Cellulose Content ◽  
Sri Lankan ◽  
Asian Countries ◽  
Chemical Methods ◽  
Rice Varieties ◽  
Wet Chemical

As rice is the staple food of most Asian countries, rice straw has become one of the largest agricultural wastes in Asia. It has not been subjected to adequate value additions yet. However, it has excellent potential to be converted to valuable materials, as it contains a significant amount of cellulose. Therefore, it would be beneficial in many ways to identify the cellulose yields of straws of different rice varieties. In general, the cellulose content of biomass is determined by wet chemical methods. Though these methods are accurate, they are not convenient to use under industrial conditions. This research work focuses on investigating the potential of thermal analysis as an alternative way to predict cellulose yields. For the study, rice straws of most frequently cultivated traditional Sri Lankan rice varieties: Suwandel and Raththal, as well as technically modified Sri Lankan rice varieties: BG300 and BG352, were selected. The results obtained by the proposed method were validated by an established three-step chemical extraction process.

Effect of extraction method on phenolic content and antioxidant activity of mistletoe extracts from Viscum album subsp. abietis

2014 ◽  
Vol 68 (7) ◽  
Author(s):  
Wioleta Pietrzak ◽  
Renata Nowak ◽  
Marta Olech
Keyword(s):  
Antioxidant Activity ◽  
Extraction Efficiency ◽  
Antioxidant Activities ◽  
Total Content ◽  
Viscum Album ◽  
Extraction Methods ◽  
Solvent Mixtures ◽  
Ultrasound Assisted Extraction ◽  
Extraction Technology ◽  
Considerable Saving

AbstractThe total content of polyphenols and flavonoids determined in the same plant and their corresponding antioxidant activities may vary widely, depending on the extraction conditions applied. This study was conducted to optimise the extraction conditions of phenolics and flavonoids from the mistletoe plant. Various extraction methods, i.e. ultrasound-assisted extraction technology, maceration, maceration with stirring, accelerated solvent extraction (ASE), and extraction under reflux were evaluated for their percentage extraction of polyphenols (TPC) and flavonoids (TFC) from Viscum album subsp. abietis. In addition, the anti-radical activity of extracts was analysed using the 2,2-diphenyl-1-picrylhydrazyl method. The effects of temperature, solvent type, and concentration on the phenolic extraction efficiency and antioxidant activity were studied using chemometric and statistical methods. The results showed that the extracts of V. album subsp. abietis contained large amounts of polyphenols and flavonoids (up to 57.673 mg g−1 and 9.955 mg g−1 of dry extract, respectively) and exhibited potent antioxidant activity, hence representing promising sources of powerful antioxidants. Due to its high extraction efficiency and considerable saving of time and solvent, ASE was more effective than the other extraction techniques. Extracts prepared with water-polar solvent mixtures displayed the highest TPC, TFC, and antioxidant activity, while organic polar solvents were the least efficient extractants.

scholarly journals IN VITRO BINDING OF NUCLEIC ACIDS TO TISSUE SECTIONS AFTER REMOVAL OF TISSUE NUCLEIC ACIDS

1964 ◽  
Vol 12 (8) ◽  
pp. 640-645 ◽  
Author(s):  
R. DAOUST
Keyword(s):  
Nucleic Acids ◽  
Extraction Methods ◽  
Organ Specificity ◽  
Chemical Extraction ◽  
Nucleic Acid Binding ◽  
Cytoplasmic Staining ◽  
Tissue Sections ◽  
In Vitro Binding ◽  
Vitro Binding

Rat tissue sections were freed from nucleic acids by enzymatic or chemical extraction methods, immersed in solutions of nucleic acids from various sources and stained with toluidine blue. Tissue sections immersed in solutions of DNA showed intense nuclear and cytoplasmic staining; similar results were obtained with tissue sections placed in solutions of RNA. Thus both DNA and RNA can bind to nuclear and cytoplasmic sites in tissue sections freed from nucleic acids. The experiments indicated however that in vitro binding of nucleic acids to tissue sections was not specific to original sites of nucleic acid binding and the reactions showed no particular species or organ specificity.

Sign in / Sign up

Export Citation Format

Share Document