scholarly journals Іnvestigation of gel formation peculiarities and properties of hydrogels obtained by the structuring of acrylamide prepolymers

2021 ◽  
Vol 4 (1) ◽  
pp. 179-185
Author(s):  
O. V. Maikovych ◽  
◽  
I. A. Dron ◽  
N. M. Bukartyk ◽  
O. Yu. Bordeniuk ◽  
...  
Keyword(s):  
Chemical Properties ◽  
Hydrogen Index ◽  
Polymeric Matrix ◽  
Gel Formation ◽  
Optimum Conditions ◽  
Polymeric Derivative ◽  
Wide Range ◽  
Polymer Framework

The paper represents the results of the investigation of the formation of a polymeric matrix of hydrogel due to the structuring of polyacrylamide using its reactive polymeric derivative – poly-N- (hydroxymethyl) acrylamide. Research determined zones of optimum conditions of synthesis and characterized hydrogel depending on pH of media, the ratio between the concentration of prepolymers, and time of synthesis. The investigation of the reaction mixture showed that the hydrogen index of the synthesis of hydrogels is one of the important factors, which in the design of the polymer framework of hydrogels allows regulating their colloidal chemical properties in a wide range.

scholarly journals Palladium and Copper: Advantageous Nanocatalysts for Multi-Step Transformations

Nanomaterials ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 1891
Author(s):  
Antonio Reina ◽  
Trung Dang-Bao ◽  
Itzel Guerrero-Ríos ◽  
Montserrat Gómez
Keyword(s):  
Chemical Properties ◽  
Added Value ◽  
Solid Supports ◽  
Nanosized Materials ◽  
Nano Structures ◽  
Liquid Phases ◽  
Wide Range ◽  
Synthetic Methodologies ◽  
Physical And Chemical ◽  
A Current

Metal nanoparticles have been deeply studied in the last few decades due to their attractive physical and chemical properties, finding a wide range of applications in several fields. Among them, well-defined nano-structures can combine the main advantages of heterogeneous and homogenous catalysts. Especially, catalyzed multi-step processes for the production of added-value chemicals represent straightforward synthetic methodologies, including tandem and sequential reactions that avoid the purification of intermediate compounds. In particular, palladium- and copper-based nanocatalysts are often applied, becoming a current strategy in the sustainable synthesis of fine chemicals. The rational tailoring of nanosized materials involving both those immobilized on solid supports and liquid phases and their applications in organic synthesis are herein reviewed.

scholarly journals In-Situ Cosmogenic 14C: Production and Examples of its Unique Applications in Studies of Terrestrial and Extraterrestrial Processes

Radiocarbon ◽  
2001 ◽  
Vol 43 (2B) ◽  
pp. 731-742 ◽  
Author(s):  
D Lal ◽  
A J T Jull
Keyword(s):  
Half Life ◽  
Earth Science ◽  
Chemical Properties ◽  
Radioactive Isotopes ◽  
Earth’S Atmosphere ◽  
The Earth ◽  
Wide Range ◽  
History Of ◽  
Earth's Atmosphere

Nuclear interactions of cosmic rays produce a number of stable and radioactive isotopes on the earth (Lai and Peters 1967). Two of these, 14C and 10Be, find applications as tracers in a wide variety of earth science problems by virtue of their special combination of attributes: 1) their source functions, 2) their half-lives, and 3) their chemical properties. The radioisotope, 14C (half-life = 5730 yr) produced in the earth's atmosphere was the first to be discovered (Anderson et al. 1947; Libby 1952). The next longer-lived isotope, also produced in the earth's atmosphere, 10Be (half-life = 1.5 myr) was discovered independently by two groups within a decade (Arnold 1956; Goel et al. 1957; Lal 1991a). Both the isotopes are produced efficiently in the earth's atmosphere, and also in solids on the earth's surface. Independently and jointly they serve as useful tracers for characterizing the evolutionary history of a wide range of materials and artifacts. Here, we specifically focus on the production of 14C in terrestrial solids, designated as in-situ-produced 14C (to differentiate it from atmospheric 14C, initially produced in the atmosphere). We also illustrate the application to several earth science problems. This is a relatively new area of investigations, using 14C as a tracer, which was made possible by the development of accelerator mass spectrometry (AMS). The availability of the in-situ 14C variety has enormously enhanced the overall scope of 14C as a tracer (singly or together with in-situ-produced 10Be), which eminently qualifies it as a unique tracer for studying earth sciences.

scholarly journals Commercial Cokes and Graphites as Anode Materials for Lithium - Ion Cells

1997 ◽  
Vol 496 ◽  
Author(s):  
David J. Derwin ◽  
Kim Kinoshita ◽  
Tri D. Tran ◽  
Peter Zaleski
Keyword(s):  
Electron Microscopy ◽  
Ethylene Carbonate ◽  
Average Particle Size ◽  
Chemical Properties ◽  
Lithium Ion ◽  
Reversible Capacity ◽  
Bet Surface Area ◽  
Average Particle ◽  
Electrochemical Characteristics ◽  
Wide Range

AbstractSeveral types of carbonaceous materials from Superior Graphite Co. were investigated for lithium ion intercalation. These commercially available cokes, graphitized cokes and graphites have a wide range of physical and chemical properties. The coke materials were investigated in propylene carbonate based electrolytes and the graphitic materials were studied in ethylene carbonate / dimethyl solutions to prevent exfoliation. The reversible capacities of disordered cokes are below 230 mAh / g and those for many highly ordered synthetic (artificial) and natural graphites approached 372 mAh / g (LiC6). The irreversible capacity losses vary between 15 to as much as 200 % of reversible capacities for various types of carbon. Heat treated cokes with the average particle size of 10 microns showed marked improvements in reversible capacity for lithium intercalation. The electrochemical characteristics are correlated with data obtained from scanning electron microscopy (SEM), high resolution transmission electron microscopy (TAM), X - ray diffraction (XRD) and BET surface area analysis. The electrochemical performance, availability, cost and manufacturability of these commercial carbons will be discussed.

Adsorption–Desorption Characteristics of ss-DNA on 2D TpTta-COF Studied by Fluorescently Labeled Oligonucleotides

NANO ◽  
2021 ◽  
pp. 2150050
Author(s):  
Zhaoyu Han ◽  
Sen Li ◽  
Shaoxian Yin ◽  
Zhi-Qin Wang ◽  
Yanfei Cai ◽  
...  
Keyword(s):  
Chemical Properties ◽  
Kinetic Mechanism ◽  
Optical Biosensors ◽  
Desorption Kinetic ◽  
Wide Range ◽  
Potential Applications ◽  
Fluorescently Labeled Oligonucleotides ◽  
Adsorption Desorption ◽  
Physical And Chemical ◽  
And Chemical Properties

Being the newest member of the 2D materials family, 2D-nanosheet possesses many distinctive physical and chemical properties resulting in a wide range of potential applications. Recently, it was discovered that 2D COF can adsorb single-stranded DNA (ss-DNA) efficiently as well as usefully to quench fluorophores. These properties make it possible to prepare DNA-based optical biosensors using 2D COF. While practical analytical applications are being demonstrated, the fundamental understanding of binding between 2D COF and DNA in solution received relatively less attention. In this work, we carried out a systematic study to understand the adsorption and desorption kinetic, mechanism, and influencing factors of ss-DNA on the surface of 2D COF. We demonstrated that shorter DNAs are adsorbed more rapidly and bind more tightly to the surface of 2D COF. The adsorption is favored by a higher pH. The different buffer types also can affect the adsorption. In Tris-HCl solution, the adsorption reached highest efficiency. By adding the complementary DNA (cDNA), desorption of the absorbed DNA on 2D COF can be achieved. Further, desorption efficiency can also be exchanged by various surfactant in solution. These findings are important for further understanding of the interactions between DNA and COFs and for the optimization of DNA and COF-based devices and sensors.

scholarly journals Influence of Fuel Chemical Properties on Soot Emissions From Gas Turbine Combustors

1989 ◽  
Author(s):  
J. S. Chin ◽  
A. H. Lefebvre
Keyword(s):  
Chemical Composition ◽  
Gas Turbine ◽  
Hydrogen Content ◽  
Continuous Flow ◽  
Empirical Relationship ◽  
Chemical Properties ◽  
Smoke Point ◽  
Fuel Composition ◽  
Wide Range ◽  
Soot Emissions

The influence of fuel composition on soot emissions from continuous flow combustors is examined. A study of the combustion characteristics of a wide range of present and potential aviation fuels suggests that smoke point provides a better indication of sooting tendency than does hydrogen content. It is concluded from this study that the best empirical relationship between fuel chemical composition and soot emissions is one which combines two fuel composition parameters — smoke point and naphthalene content — into a single parameter which is shown to correlate successfully soot emissions data acquired from several different fuels burning in a variety of gas turbine and model combustors.

scholarly journals A review on conductometric studies of electrolytes in mixed solvent systems to understand ion-ion and ion-solvent interactions

2020 ◽  
Vol 10 (3) ◽  
pp. 5355-5360
Keyword(s):  
Mixed Solvent ◽  
Mixed Solvents ◽  
Chemical Properties ◽  
Electrolyte Solutions ◽  
Molar Conductance ◽  
Extensive Literature ◽  
Solvent Interactions ◽  
Physico Chemical ◽  
Wide Range ◽  
Solvent Systems

The study of ion- solvent interaction is of much importance to investigate the nature of different solutions. Measurement of electrical conductivity and evaluation of physico-chemical properties, such as molar conductance, limiting molar conductance, ion-pair association, Walden product etc. shade light on different intermolecular interactions present in electrolyte solutions. Solvation properties can be varied by mixing two or more solvents. An extensive literature survey on conductometric studies has been carried out on different electrolytes dissolved in a wide range of mixed solvent systems. The reported results show that strong solute-solute, solute-solvent and solvent-solvent interactions are responsible for the physico- chemical behavior of a solution in mixed solvents.

scholarly journals Peculiarities of the Physicochemical Properties of Hydrated C60 Fullerene Solutions in a Wide Range of Dilutions

2021 ◽  
Vol 9 ◽  
Author(s):  
O. Yablonskaya ◽  
E. Buravleva ◽  
K. Novikov ◽  
V. Voeikov
Keyword(s):  
Chemical Properties ◽  
Buffering Capacity ◽  
Deionized Water ◽  
Physical And Chemical Properties ◽  
Aqueous Systems ◽  
Wide Range ◽  
High Dilutions ◽  
Physical And Chemical ◽  
Control Water ◽  
And Chemical Properties

Hydrated fullerene C60 (HyFn) is a supramolecular object in which the nanosized fullerene molecule is enclosed in a multilayer shell of water molecules. Despite the fact that fullerene C60 is chemically rather inert, aqueous solutions of HyFn exhibit a wide spectrum of biological activity in particular in low and ultra-low concentrations. Thus, physical and chemical properties of aqueous solutions of HyFn in a wide range of its dilutions are of interest. Here we compared some physical and chemical properties of aqueous systems prepared by successive 100-fold dilutions of HyFn (10–7 M) with deionized water, with their intensive shaking at each stage up to the calculated HyFn concentration of 10–31 M and of the corresponding “dilutions” of deionized water prepared in the same manner (controls). We studied the character of рН changes in dilutions when titrating them with HCl and NaOH. It turned out that HyFn dilutions had significantly higher buffering capacity against acidification with HCl than control water “dilutions.” At the highest acidity reached pH in all HyFn dilutions was almost 0.3 units higher than in the respective controls. Average buffering capacity of HyFn dilutions and water controls when titrated with NaOH did not differ. However, differences in buffering capacity could be seen between consecutive dilutions of HyFn at their titration either with NaOH or with HCl. Most prominent differences were observed between consecutive HyFn dilutions in the range of calculated concentrations 10–17–10–31 M titrated with NaOH while no significant differences in pH between equivalent “dilutions” of control water were observed. Similar though less prominent variations in buffering capacity between consecutive HyFn dilutions titrated with HCl were also noticed. Thus, titration with an acid and especially with an alkali made it possible to reveal differences between individual dilutions of HyFn, as well as differences between HyFn dilutions and corresponding dilutions of water. These features may be due to complexity in the structural properties of aqueous systems, which, supposedly, can arise due to the emergence of heterogenous aqueous regions (“clouds”) in the course of their dilutions with intensive mixing at each stage. In order to find out if such heterogeneity is a characteristic for HyFn dilutions we used the method of drying microsphere-containing droplets, whose aqueous base were either HyFn dilutions in the range of calculated HyFn concentration 10–7–10–31 M or respective water controls. It was found that a significant part of HyFn dilutions is characterized by mesoscopic heterogeneity. It showed up by the tendency of microspheres to concentrate in a specific way resembling ornaments once the droplets had dried. As the degree of HyFn dilution increased, the number of dried droplets with an ornament-like microsphere distribution increased. Same was also observed in water control drops. However, for the dilutions of HyFn equivalent to concentrations 10–19–10–31 M the percentage of complexly structured dried up droplets reached 60–80%, while for dried out drops of respective water controls it did not exceed 15–20%. Thus, the physicochemical properties of high dilutions of hydrated fullerene differ not only from each other dependently on the dilution level, but also from those of high dilutions of water, which can be explained by the structuredness and heterogeneity of these aqueous systems. Therefore, upon dilution process the properties of the solutions change according to complex and non-linear laws so that final dilutions cannot be identical in their properties and features to those of the initial solutions (before dilutions process) and to the untreated water. Dilution process, in view of the aforementioned, should not be underestimated when analyzing properties of the solutions, having shown to be able to affect dramatically properties of the solutions.

scholarly journals Effects of Liming on Dithionate and Oxalate Extractable Aluminium in Acid Soils

2020 ◽  
pp. 1-9
Author(s):  
Esther Mwende Muindi
Keyword(s):  
Crop Production ◽  
Block Design ◽  
Chemical Properties ◽  
Acid Soils ◽  
P Availability ◽  
Acidic Soils ◽  
Training Centre ◽  
Wide Range ◽  
World Information ◽  
Considerable Work

Liming and phosphorus (P) applications are recommended practices for improving crop production in acid soils of the tropics. Although considerable work has been done to establish liming rates for acid soils in many parts of the world, information on the effects of lime on the forms of aluminium which actively sorb P in such soils is minimal. A greenhouse pot experiment was conducted at Waruhiu Farmers Training Centre, Githunguri to evaluate the effect of liming on oxalate and dithionate extractable aluminium in acid soils. Extremely (pH 4.48) and strongly (pH 4.59) acidic soils were evaluated. Four liming (CaO) rates namely 0, 2.2, 5.2 and 7.4 tonnes ha-1 for extremely acidic and 0, 1.4, 3.2, and 4.5 tonnes ha-1 for  strongly acidic soils were evaluated. The experiment was laid out in a Randomized Complete Block Design (RCBD) and replicated three times. Data collected included: initial soil chemical properties, oxalate (Alo) and dithionate (Ald) aluminium levels. The tested soils had high exchangeable Al (> 2 cmol Al kg-1), Al saturation of (> 20% Al) and low extractable P values (< 15 mg P kg-1 soil). Liming significantly (p=.05) reduced Alo by 70% and 68% in extremely and strongly acidic soils respectively and Ald by 78% in both extremely and strongly acidic soils compared to control. Use of 7.4 tonnes ha-1 of lime in extremely acidic soils and 4.5 tonnes ha-1 of lime in strongly acidic soils significantly (p=.05) reduced both Alo and Ald by > 68% compared to no lime. It was, therefore, concluded that liming contributes to the reduction of soluble Alo and Ald in acid soils of the Kenya highlands leading to increased soluble P availability. Studies are required to provide short and long term optimal liming rates that reduce Alo and Ald without distabilizing availability of other nutrients in field conditions under wide range of acid soils.

212 Fatty Acid Analysis and Composition in Meat by Mass Spectrometry

2021 ◽  
Vol 99 (Supplement_3) ◽  
pp. 111-112
Author(s):  
Thu Dinh
Keyword(s):  
Mass Spectrometry ◽  
Fatty Acids ◽  
Fatty Acid ◽  
Methyl Esters ◽  
Meat Products ◽  
Chemical Properties ◽  
Fatty Acid Analysis ◽  
Animal Fats ◽  
Wide Range ◽  
Mass Spectrometry Technology

Abstract Fatty acids determine the physical and chemical properties of fats. Animal fats, regardless of species, have more saturated and monounsaturated than polyunsaturated fatty acids. The major fatty acids in meat are palmitic (16:0), stearic (18:0), palmitoleic (16:1), oleic (18:1), linoleic (18:2), and linolenic (18:3) acids, among which oleic acid is the most predominant. Arachidonic acid (20:4 cis 5,8,11,14) is an essential fatty acid only found in animal fats and can be used as a quality control indicator in the fatty acid analysis. Fatty acid analysis has been traditionally performed by gas chromatography (GC) of volatile fatty acid derivatives, prominently the methyl esters, and flame ionization detection (FID), in which the carbon chain of fatty acids is degraded to the formylium ion CHO+. The FID is very sensitive and is the most widely used detection method for GC, providing a linear response, i.e., peak area, over a wide range of concentrations. Researchers have been used the FID peak area to calculate the percentages of fatty acids. However, the FID is a “carbon counter” and relies on the “equal per carbon” rule; therefore, at the same molar concentration, fatty acids with a different number of carbons produce different peak areas. The recent development of mass spectrometry technology has improved the specificity of fatty acid detection. Specific target and qualifier ions provide better identification and more accurate quantification of fatty acid concentrations. Although fatty acids can be identified through comparing ion fragmentation with various databases, authentic standards are needed for quantification purposes. Using mass spectrometry, more than 50 fatty acids have been identified in meat samples. Some branched-chain fatty acids may have flavor, safety, and shelf life implications in meat products.

scholarly journals Proanthocyanidins: Oligomeric Structures with Unique Biochemical Properties and Great Therapeutic Promise

2012 ◽  
Vol 7 (3) ◽  
pp. 1934578X1200700 ◽  
Author(s):  
Zhanjie Xu ◽  
Peng Du ◽  
Peter Meiser ◽  
Claus Jacob
Keyword(s):  
Protein Interactions ◽  
Biological Activities ◽  
Antioxidant Properties ◽  
Chemical Properties ◽  
Cancer Chemoprevention ◽  
Biochemical Properties ◽  
Synthetic Methods ◽  
Practical Applications ◽  
Wide Range ◽  
Physical And Chemical

Proanthocyanidins represent a unique class of oligomeric and polymeric secondary metabolites found ubiquitously and in considerable amounts in plants and some algae. These substances exhibit a range of rather surprising physical and chemical properties which, once applied to living organisms, are translated into a multitude of biological activities. The latter include antioxidant properties, cancer chemoprevention, anti-inflammatory and anti-diabetic effects as well as some exceptional, yet highly interesting activities, such as anti-nutritional and antimicrobial activity. Despite the wide range of activities and possible medical/agricultural applications of proanthocyanidins, many questions still remain, including issues related to bioavailability, metabolism and the precise biochemical, extra- and intracellular targets and mode(s) of action of these highly potent materials. Among the various physical and chemical interactions of such substances, strong binding to proteins appears to form the basis of many of their biological activities. Once easy-to-use synthetic methods to produce appropriate quantities of pure proanthocyanidins are available, it will be possible to identify the prime biological targets of these oligomers, study oligomer-protein interactions in more detail and develop possible practical applications in medicine and agriculture.

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