scholarly journals Piezoelectric resonance sensor for the determination of ammonium in aqueous environment

2016 ◽  
Vol 58 (1.2) ◽  
pp. 1-8
Author(s):  
DURKUT Serap; ŞEKER
Keyword(s):  
Aqueous Environment ◽  
Piezoelectric Resonance ◽  
Resonance Sensor

scholarly journals EXAFS Determination of Clay Minerals in Martian Meteorite Allan Hills 84001 and Its Implication for the Noachian Aqueous Environment

Minerals ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 176
Author(s):  
Ryoichi Nakada ◽  
Gaku Tanabe ◽  
Iori Kajitani ◽  
Tomohiro Usui ◽  
Masashi Shidare ◽  
...  
Keyword(s):  
Silica Glass ◽  
Large Body ◽  
Aqueous Environment ◽  
Martian Surface ◽  
Exafs Analysis ◽  
Martian Meteorite ◽  
Fe Species ◽  
Allan Hills 84001 ◽  
X Ray Absorption

The aqueous environment of ancient Mars is of significant interest because of evidence suggesting the presence of a large body of liquid water on the surface at ~4 Ga, which differs significantly from the modern dry and oxic Martian environment. In this study, we examined the Fe-bearing minerals in the 4 Ga Martian meteorite, Alan Hills (ALH) 84001, to reveal the ancient aqueous environment present during the formation of this meteorite. Extended X-ray absorption fine structure (EXAFS) analysis was conducted to determine the Fe species in ALH carbonate and silica glass with a high spatial resolution (~1–2 μm). The μ-EXAFS analysis of ALH carbonate showed that the Fe species in the carbonate were dominated by a magnesite-siderite solid solution. Our analysis suggests the presence of smectite group clay in the carbonate, which is consistent with the results of previous thermochemical modeling. We also found serpentine in the silica glass, indicating the decrease of water after the formation of carbonate, at least locally. The possible allochthonous origin of the hematite in the carbonate suggests a patchy redox environment on the ancient Martian surface.

Derivatization and Cleanup Improvements in Determination of Residues of Glyphosate and Aminomethylphosphonic Acid in Blueberries

1982 ◽  
Vol 65 (1) ◽  
pp. 35-39 ◽  
Author(s):  
Richard A Guinivan ◽  
Neal P Thompson ◽  
Willis B Wheeler
Keyword(s):  
Handling Time ◽  
Low Ph ◽  
Electron Capture Detection ◽  
Aqueous Environment ◽  
Sample Handling ◽  
Aminomethylphosphonic Acid ◽  
Gel Permeation ◽  
Cation Exchange Column ◽  
Derivatives Of

Abstract A new method based on development of the 2-chloroethyl N-heptafluorobutyryl derivatives of glyphosate and its major metabolite aminomethylphosphonic acid is reported for fortified blueberry samples. The concentrated aqueous extract is chromatographed on a gel permeation column in a low pH eluant. Under these conditions, sugar is eliminated by permeation and pigments are strongly adsorbed. Additional sugar is eliminated with a small cation exchange column and then the sample is easily dried and derivatized. The derivatized compounds are extracted from an aqueous environment with hexane and analyzed by gas chromatography with electron capture detection. This procedure requires significantly less sample handling time and provides greater sensitivity for glyphosate than the commonly used procedure recommended by EPA.

scholarly journals Swelling of Hydrogels Based on Carboxymethylated Starch and Poly(Acrylic Acid): Nonlinear Rheological Approach

Polymers ◽  
2020 ◽  
Vol 12 (11) ◽  
pp. 2564
Author(s):  
Grzegorz Kowalski ◽  
Paweł Ptaszek ◽  
Łukasz Kuterasiński
Keyword(s):  
Acrylic Acid ◽  
Aqueous Environment ◽  
Large Amplitude Oscillatory Shear ◽  
Gel Structure ◽  
Swelling Behaviour ◽  
Molar Ratios ◽  
Modified Starches ◽  
High Amylose ◽  
Covalent Interactions

In this paper, the authors discuss the results of research on the preparation and properties of superabsorbent hydrogels based on carboxymethylated high-amylose corn starches. They were obtained by graft copolymerisation (in an aqueous environment) of acrylic acid and its sodium salt onto modified starches (with various substitution degrees DS = 0.2 and 0.8), using potassium persulfate as an initiator and N,N’-methylenebisacrylamide (MBA) as a cross-linker. Modified starches, with various DS, were used to synthesise two series of hydrogels with varying molar ratios of cross-linkers to monomers. The swelling behaviour of hydrogels was studied and their properties were estimated using the kinetic equation. The occurrence of starch–polyacrylic acid covalent interactions was demonstrated by FTIR analysis. Nonlinear rheological methods have proved to be very effective in assessing the mechanical properties of hydrogels. LAOS (large -amplitude oscillatory shear) analysis allowed the determination of the durability of the gel structure as a function of the amount of absorbed water.

Determination of ammonia in the air using piezoelectric resonance sensors coated with humic acids

2010 ◽  
Vol 65 (4) ◽  
pp. 414-417
Author(s):  
A. A. Zvyagin ◽  
D. V. Nenakhov ◽  
S. N. Korchagina ◽  
A. V. Shaposhnik ◽  
V. V. Kotov ◽  
...  
Keyword(s):  
Humic Acids ◽  
Piezoelectric Resonance

scholarly journals Voltammetric Characterization of the Behavior of Biologically Active Compound Enoxil in Various Media

2011 ◽  
Vol 6 (1) ◽  
pp. 62-68
Author(s):  
Gheorghe Nemţoi ◽  
Tudor Lupaşcu ◽  
Alexandra Ciomaga ◽  
Alexandru Cecal
Keyword(s):  
Sodium Perchlorate ◽  
Reduction Process ◽  
Oxidation Potential ◽  
Biologically Active ◽  
Aqueous Environment ◽  
Cathodic Current ◽  
Oxidation Reduction ◽  
Complex Preparation

This paper presents the results of scientific research related to the electrochemical behavior of the complex preparation Enoxil. It was established that the oxidation-reduction process of Enoxil is quasireversible. The reactivity of Enoxil obtained from alcohol soluble enotannins is more pronounced, compared to that obtained from standard enotannins. The dependence of cathodic current intensity on Enoxil concentration is linear. This can be used to establish Enoxil concentration in solution. Cyclic voltamograms were used to establish reduction and oxidation potential and the formal redox potential on platinum electrode in sodium perchlorate aqueous environment. These features can be used for identification and determination of Enoxil in pharmaceuticals.

scholarly journals The Influence of the Environment on the Properties of Hybrid Cement-Based Concrete with Steel and Air-Cooled Slags

Crystals ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 1087
Author(s):  
Pavel Martauz ◽  
Vojtěch Václavík ◽  
Branislav Cvopa
Keyword(s):  
Steel Slag ◽  
Blended Cement ◽  
Physical And Mechanical Properties ◽  
Outdoor Environment ◽  
Aqueous Environment ◽  
Test Results ◽  
Mixture Designs ◽  
Natural Aggregates ◽  
By Products

This article presents the results of research that dealt with the development of non-traditional concrete using a hybrid alkali-activated cement. It is concrete based on by-products from a metallurgical plant that replaced 100% of the natural aggregates. Steel slag (CSS, fraction: 0/8 mm) was used as a filler in combination with air-cooled slag (ACBFS, fraction: 8/16 mm and 16/32 mm). Portland blended cement (CEM II/B-S 42.5N) and H-CEMENT were used as binding components in the development of the concrete mixture designs. Both of these cements were produced by Považská cementáreň, a.s., Ladce. Attention was focused on testing the physical and mechanical properties of the developed concretes in various environments. An aqueous environment was selected as the first environment for the placement of test specimens (cubes with 150 mm edges and prisms with dimensions of 100 × 100 × 400 mm3) according to the ČSN EN 206-1 standard and the outdoor environment (August to October). The determination of the cube strength was made after 7, 28, and 90 days, the determination of the flexural and compressive strength was made at the end of the prisms, and the determination of the dynamic modulus of elasticity was made after 28 days on the prisms. The test results of the test specimens, which were placed in two environments, were compared and it was found that, after 90 days, the outdoor environment caused a decrease in the concrete’s strength characteristics when using Portland blended cement (CEM II/ B-S 42.5N) of about 8%; in contrast, when using H-CEMENT, the concrete’s strength increased by about 14%. The use of H-CEMENT and the addition of PUZZOLANIT in the amount of 30% in combination with CEM II/B-S 42.5N in the amount of 70% reduced the decrease in the strength of the concrete after 90 days by about 3%. The research results confirm the suitability of using H-CEMENT and the addition of PUZZOLANIT for the production of concrete based on steel slag (CSS) and air-cooled slag (ACBFS).

scholarly journals Iron-based magnetic molecular imprinted polymers and their application in removal and determination of di- n -pentyl phthalate in aqueous media

2017 ◽  
Vol 4 (8) ◽  
pp. 170672 ◽  
Author(s):  
Jing Li ◽  
Qingxiang Zhou ◽  
Yongyong Yuan ◽  
Yalin Wu
Keyword(s):  
Limit Of Detection ◽  
Solid Phase ◽  
Physical Adsorption ◽  
Aqueous Media ◽  
Aqueous Environment ◽  
Chromatography Method ◽  
Molecular Imprinted Polymers ◽  
Imprinted Polymers ◽  
Iron Based

Iron-based magnetic molecular imprinted polymers (Fe@SiO 2 @MIP) were synthesized for highly selective removal and recognition of di- n -pentyl phthalate (DnPP) from water. Well-defined core-shell Fe@SiO 2 nanoparticles (less than 70 nm) were decorated on MIPs reticular layers to endow DnPP-MIPs with magnetic property for the first time. Five other phthalic acid esters including dimethyl phthalate, diethyl phthalate, dipropyl phthalate, di- n -butyl phthalate and di-iso-octyl phthalate were used to investigate the adsorptive selectivity to DnPP. The designed experiments were carried out to explore the adsorption kinetics, isotherms and thermodynamics and the results demonstrated that the adsorption was a spontaneous, exothermal and physical adsorption process. The materials were proved to be excellent adsorbents in removal of DnPP with an adsorption capacity as high as 194.15 mg g −1 in optimal condition. Furthermore, a magnetic solid phase extraction with Fe@SiO 2 @MIP coupled to high-performance liquid chromatography method was successfully developed for the determination of DnPP, and the proposed method achieved a good linear range of 0.5–250 µg l −1 with a correlation coefficient ( R 2 ) of 0.999 and low limit of detection (LOD) of 0.31 µg l −1 . These materials exhibited excellent capacity in removal and highly sensitive identification of DnPP from aqueous environment samples, and opened a valuable direction for developing new adsorbents for the removal and enrichment of important pollutants.

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