Oxygen-containing Functions Research Articles

Green synthesis of reduced graphene oxide (rGO) and its applications in non-enzymatic electrochemical glucose sensors

The synthesis of reduced graphene oxide (rGO) is a challenging task for industrial applications due to the absence of a simple and cost-effective synthesis method. This study proposes an environmentally friendly approach to synthesizing rGO using cow urine as a reducing agent, which eliminates the use of hazardous chemicals. The efficacy of this method was confirmed through various analyses, including UV Vis, Fourier transform infrared, and X-ray diffraction, which demonstrated the successful removal of oxygen-containing functions in GO via reduction with cow urine. The synthesized rGO-10 was utilized to fabricate electrochemical nonenzymatic glucose sensors, which exhibited a rapid response time and excellent amperometry response. The sensors used in this study demonstrated a sensitivity of 19.17 μAcm−2mM−1 when optimized for a glucose concentration of 2 mM in human serum. The sensors demonstrated a wide response range, covering a range of 0.2 to 10 mM, and a low detection limit of 1.9019 µM. Additionally, the sensors displayed desirable attributes about repeatability, reproducibility, and stability.

Phytochemistry and Pharmacological Activities of the Diterpenoids from the Genus Daphne.

There are abundant natural diterpenoids in the plants of the genus Daphne from the Thymelaeaceae family, featuring a 5/7/6-tricyclic ring system and usually with an orthoester group. So far, a total of 135 diterpenoids has been isolated from the species of the genus Daphne, which could be further classified into three main types according to the substitution pattern of ring A and oxygen-containing functions at ring B. A variety of studies have demonstrated that these compounds exert a wide range of bioactivities both in vitro and in vivo including anticancer, anti-inflammatory, anti-HIV, antifertility, neurotrophic, and cholesterol-lowering effects, which is reviewed herein. Meanwhile, the fascinating structure–activity relationship is also concluded in this review in the hope of providing an easy access to available information for the synthesis and optimization of efficient drugs.

A Review on Daphnane-Type Diterpenoids and Their Bioactive Studies.

Natural daphnane diterpenoids, mainly distributed in plants of the Thymelaeaceae and Euphorbiaceae families, usually include a 5/7/6-tricyclic ring system with poly-hydroxyl groups located at C-3, C-4, C-5, C-9, C-13, C-14, or C-20, while some special types have a characteristic orthoester motif triaxially connectedat C-9, C-13, and C-14. The daphnane-type diterpenoids can be classified into five types: 6-epoxy daphnane diterpenoids, resiniferonoids, genkwanines, 1-alkyldaphnanes and rediocides, based on the oxygen-containing functions at rings B and C, as well as the substitution pattern of ring A. Up to now, nearly 200 daphnane-type diterpenoids have been isolated and elucidated from the Thymelaeaceae and Euphorbiaceae families. In-vitro and in-vivo experiments of these compounds have shown that they possess a wide range of biological activities, including anti-HIV, anti-cancer, anti-leukemic, neurotrophic, pesticidal and cytotoxic effects. A comprehensive account of the structural diversity is given in this review, along with the cytotoxic activities of daphnane-type diterpenoids, up to April 2019.

Influence of activation time on the microstructure and antibacterial activity of Nanosilver-containing activated carbon fibers prepared from liquefied wood

Liquefied wood-based carbon fibers activated for different periods of time were modified by silver to produce nanosilver-containing activated carbon fibers (WACF/Ag). The microstructure and antibacterial activities of WACF and WACF/Ag were studied in this work. The results showed that WACF activated for longer periods of time had richer porosity and higher content active carbon-hydrogen bonds. More silver nanoparticles were found on WACF activated for longer periods of time. After loading silver on WACF, the relative contents of element carbon and graphitic carbon on fibers decreased, whereas those of elements oxygen and carbon bonded to oxygen-containing functions increased. With an increase in activation time, the changing ratios for elements oxygen and nitrogen gradually increased, while those for most of carboncontaining functions decreased. Meanwhile, as the activation time increased, the increasing silver particles were distributed on the surface and in pores of WACF, leading to the increasing micropores and mesopores of fibers were blocked by silver nanoparticles. The antibacterial activity of WACF/Ag was strengthened by increasing the activation time of WACF.

Soft Oxidation of Single-Walled Carbon Nanotube Samples

Thermal dry oxidation treatment is a straightforward and commonly used technique in carbon nanotube (CNT) processing. Among its advantages, it plays a key role in guaranteeing the efficiency of numerous purification procedures. It also enables a chemical modification of the nanotube surface by covalent bonding of oxygen-containing functions. Nevertheless, a careful optimization of the experimental conditions used for the treatment is a crucial step in order to obtain the desired effect and avoid a strong damaging of the CNTs. Soft oxidation conditions are thus in particular of great interest. We report on the oxidation of CNTs in a large scale of oxidation conditions. The treated samples were characterized using several techniques including transmission electron microscopy, thermal gravimetric analysis, dispersion tests, and Raman spectroscopy to investigate both morphological and surface properties. We were thus able to discriminate between the behavior of the CNTs from that of other carbonaceous species...

EFFECT OF TEMPERATURE AND TIME ON MICROSTRUCTURE AND SURFACE FUNCTIONAL GROUPS OF ACTIVATED CARBON FIBERS PREPARED FROM LIQUEFIED WOOD

Activated carbon fibers were prepared from liquefied wood through stream activation. The effects of activation temperature and time on the microstructure and surface functional groups of the liquefied wood activated carbon fibers (LWACFs) were studied using analysis of burning behavior, X-ray diffraction, nitrogen adsorption-desorption isotherms, X-ray photoelectron spectroscopy, and SEM. The results showed that the burn-off value of the LWACFs increased gradually with the increase in temperature or time. All the LWACFs were far from being structurally graphitized, and in general, as temperature or time increased, the degree of graphitization and thickness of crystal structure increased. In addition, the LWACFs possessed rich micropores, and their specific surface area, pore volume, micropore size, and mesopore quantity were directly related to the activation temperature or time. The maximum specific surface area was found to be 2641 m2/g. The fractal dimension values of all samples were close to 3, indicating that their surfaces were very rough. Furthermore, with an increase in temperature or time, the elemental content of carbon increased, while that of oxygen decreased. Meanwhile, as the temperature or time increased, the relative content of graphitic carbon decreased, whereas that of carbon bonded to oxygen-containing functions increased. The surface of samples prepared at higher temperature or with longer time formed a considerable amount of holes.

Reoptimized interaction parameters for the peptide-backbone model compound N-methylacetamide in the GROMOS force field: Influence on the folding properties of two beta-peptides in methanol

Considering N-methylacetamide (NMA) as a model compound, new interaction parameters are developed for the amide function in the GROMOS force field that are compatible with the recently derived 53A6(OXY) parameter set for oxygen-containing chemical functions. The resulting set, referred to as 53A6(OXY+A) , represents an improvement over earlier GROMOS force-field versions in the context of the pure-liquid properties of NMA, including the density, heat of vaporization, dielectric permittivity, self-diffusion constant and viscosity, as well as in terms of the Gibbs hydration free energy of this molecule. Assuming that NMA represents an adequate model compound for the backbone of peptides, 53A6(OXY+A) may be expected to also provide an improved description of polypeptide chains. As an initial test, simulations are reported for two β-peptides characterized by very different folding properties in methanol. For these systems, earlier force-field versions provided good agreement with experimental NMR data, and the test shows that the improved description achieved in the context of NMA is not accompanied by any deterioration in the representation of the conformational properties of these peptides.

Synchrotron-Based XANES Speciation of Chromium in the Oxy-Fuel Fly Ash Collected from Lab-Scale Drop-Tube Furnace

Speciation of chromium (Cr) in the fly ash collected from oxy-firing of Victorian brown coal has been reported for the first time to address the potential formation of toxic Cr(VI) and the variation of the quantities of Cr(III)-bearing species with flue gas composition. Synchrotron-based X-ray absorption near-edge structure (XANES) was employed for Cr speciation. Apart from a pure O(2)/CO(2) mixture (27/73, v/v) versus air, the O(2)/CO(2) mixtures doped with SO(2), HCl, and steam individually or together to simulate real flue gas have also been tested. Under all of the conditions tested here, the fractions of Cr(VI) in the fly ashes are insignificant, constituting no more than 5% of the total Cr. The test of Cr-doped brown coal in pyrolysis further confirmed that the Cr(VI) formation preferentially occurred through a local oxidation of Cr(III) at the oxygen-containing functions sites within coal matrix, rather than through an oxidation by external bulk O(2). This reaction is also highly temperature-dependent and slower than the interaction between Cr(III) and other metals such as iron oxide. Increasing temperature to 1000 °C inhibited the oxidation of Cr(IIII) to Cr(VI). Shifting the combustion gas from air to O(2)/CO(2) exerted little effect on the Cr(VI) formation. Instead, the formation of iron chromite (FeCr(2)O(4)) was facilitated in O(2)/CO(2), probably due to a strong reducing microenvironment formed by the CO(2) gasification reaction within the char matrix. The accumulation of HCl in flue gas favored the vaporization of chromium as gaseous chloride/oxychloride, as expected. The coexistence of SO(2) inhibited this phenomenon by promoting the formation of sulfate. The presence of steam was even beneficial for the inhibition of water-soluble Cr sulfate through stabilizing the majority of Cr into alumino-silicate which is in the slagging phase.

New Interaction Parameters for Oxygen Compounds in the GROMOS Force Field: Improved Pure-Liquid and Solvation Properties for Alcohols, Ethers, Aldehydes, Ketones, Carboxylic Acids, and Esters.

A new parameter set (53A6OXY) is developed for the GROMOS force field, that combines reoptimized parameters for the oxygen-containing chemical functions (alcohols, ethers, aldehydes, ketones, carboxylic acids, and esters) with the current biomolecular force field version (53A6) for all other functions. In the context of oxygen-containing functions, the 53A6OXY parameter set is obtained by optimization of simulated pure-liquid properties, namely the density ρliq and enthalpy of vaporization ΔHvap, as well as solvation properties, namely the free energies of solvation in water ΔGwat and in cyclohexane ΔGche, against experimental data for 10 selected organic compounds, and further tested for 25 other compounds. The simultaneous refinement of atomic charges and Lennard-Jones interaction parameters against the four mentioned types of properties provides a single parameter set for the simulation of both liquid and biomolecular systems. Small changes in the covalent parameters controlling the geometry of the oxygen-containing chemical functions are also undertaken. The new 53A6OXY force-field parameters reproduce the mentioned experimental data within root-mean-square deviations of 22.4 kg m(-3) (ρliq), 3.1 kJ mol(-1) (ΔHvap), 3.0 kJ mol(-1) (ΔGwat), and 1.7 kJ mol(-1) (ΔGche) for the 35 compounds considered.

Studies on the mechanism of the reaction of activated carbon fibers with oxidants

In this paper, the mechanism of the reaction of activated carbon fibers (ACFs) with oxidants was studied by means of elemental analysis, surface groups analysis, X-ray photoelectron spectroscopy, gas chromatography, pH determination, and other techniques. The experimental results indicated that the reduction ability of ACF is mainly associated with the edges rather than the surface of the microcrystal carbon. The oxygen-containing functions can contribute only a small part of the reduction capacities of ACF. When ACF is oxidized by oxidants, the oxygen content and the amounts of hydroxyl, carbonyl, and carboxyl groups of ACF increase. The oxidation of ACF involves at least two processes, which are the formations of hydroxyl (or phenolic) groups and of carbonyl (or carboxyl) groups. Furthermore, the oxidation of ACF produces carbon dioxide and H + ion. The reduction capacity was larger than the amount of carbon dioxide released but approximately equal to the H + produced.

Vinyl substituent effects on the reactions of higher oxygenates on Pd(111)

The reactions of vinylic oxygenates (allyl alcohol, acrolein and acrylic acid) were compared with those of their aliphatic analogues using TPD and HREELS. The principal reaction channels of the vinylic and aliphatic oxygenates were the same: allyl alcohol, 1-propanol, acrolein and propanal all underwent decarbonylation, yielding CO, C 2H 4, H 2 and adsorbed carbonaceous species. Acrylic acid and propanoic acid both underwent decarboxylation. HREEL spectra of the respective adlayers demonstrated that all of these reagents interacted with the surface via their oxygen-containing functions: allyl alcohol gave rise to an allyl alkoxide, acrolein to a strongly rehybridized η 4(C,C,C,O)-bound species, and acrylic acid to an η 5-acrylate. However, the surface—adsorbate interaction was not limited to the oxygen functions alone. In addition to the HREELS evidence for multiple coordination of these intermediates to the surface, TPD experiments also demonstrated that each of the vinylic oxygenates exhibited an additional reaction channel not available to its aliphatic counterpart. Allyl alcohol dehydrated to produce propylene plus water, in parallel with the decarbonylation pathway noted above; some acrolein was hydrogenated to form propanal; and acrylic acid gave rise to surface ethylidynes, water, and atomic carbon and oxygen, not seen for propanoic acid. These observations suggest that vinyl—surface interactions are responsible for multip0le coordination of unsaturated oxygenates and for opening new reaction channels; the chemistry of these molecules is dominated, however, by their oxygen-containing functions and the interactions of these with the Pd(111) surface.

Surface Dynamics vs. Adhesion in Oxygen Plasma Treated Polyolefins

Abstract Polyethylene (PE) and polypropylene (PP) were oxygen plasma treated and aged in carefully reproducible conditions. The effect of aging on the surface chemistry, wettability and adhesion were studied using a combination of techniques: contact angle measurements, XPS, SSIMS, adhesion tests (shear and pull). PE was found to be relatively insensitive to aging both in terms of wettability and adhesion, due to crosslinking during plasma treatment, which is likely to reduce macromolecular mobility within the surface layer. In the case of PP, dramatic decreases of wettability occur with time, due to macromolecular motions leading to minimization of oxygen-containing functions at the surface. This behavior was shown to affect the adhesion performance of treated PP.

Origin and structure of the fossil resin from an Indonesian Miocene coal

The structure of a fossil resin from Miocene coal outcrops of the Bukit Asam region (Sumatra) has been studied. The fossil material has been formed from sesqui- and tri-terpenes from trees of the Dipterocarp family. The original terpenes have lost virtually all oxygen-containing functions and the resulting mono- and di-olefins have polymerized to a mainly non-crosslinked resin whose components have molecular weights of up to 300,000.

Structural investigations of Australian coals II: A 13C-NMR study of the humic acids from Victorian brown coal lithotypes

The experimental conditions allowing quantitative interpretation of liquid state 13C-NMR spectra of the humic acids, derived from the five Victorian brown coal lithotypes are described. The structure of the two classes of humic acids investigated for each lithotype vary significantly in their level of aromaticity, the level of polar functional groups and aliphatic chains attached to their polyaromatic skeletons. Variation is also observed in the degree of aromaticity and oxygen-containing functions of humic acids with lithotype. These data are interpreted in the light of paleobotanical evidence, which suggests that the lithotypes represent variations in depositional environment and input to the coal seam.

Plant growth activity of guaianolides with C-4 oxygen-containing groups

The plant growth activity of guaianolides with C-4 oxygen-containing functions has been studied. It was found that the presence of an epoxy or an ether link at C-4 enhanced the plant growth activity of the parent compound. The presence of a hydroxyl group at C-4 had no effect.

Mass spectra of 18α,19βH-ursane derivatives with a lactone arrangement of the ring E

The character of the mass spectra of a series of 25 18α,19βH-ursane derivatives with a six-membered or five-membered lactone bridge in the ring E does not depend, surprisingly, on the substitution in the ring E. In all instances of 3β-acetoxy- and 3β-hydroxy derivatives the dominant ions of the spectrum are formed by the loss of the methyl radical and the ethylene molecule, while the lactone ring and further oxygen-containing functions in the ring E are not fragmented.

Interaction between a coke and a tar. 1. Influence of the surface chemical functions of coke

The authors studied the relation between oxygen-containing functions of cokes and contact angles of tars on cokes. Using two different cokes, a coal-tar pitch and polymer models, they showed that the coke-tar interactions depend on the hydrogen bonding between the two components and that above a critical value surface-chemical-function content has no influence on coke-tar interactions.

Isolation and properties of the products of the covalent hydration of 4H-imidazoles

The neutralization of 5-hydroxy-4,4-dimethyl-2-imidazolinium chlorides yields in the free state the products of the covalent hydration of the corresponding 4H-imidazoles — 5-hydroxy-4, 4-dimethyl-2-imidazolines. On being heated, the compounds obtained undergo various transformations, depending on the presence and position of oxygen-containing functions: 5-hydroxy-2-imidazoline gives 2-acetylamino-2-methyl-1-phenylpropan-1-ol; 3,5-dihydroxy-2-imidazoline dehydrates to 4H-imidazole 3-oxide; and 1,5-dihydroxy-2-imidazolines are converted into 2,3-dihydro-4H-1,2,5-oxadiazines.

NMR spectra of cardenolides with an oxygen-containing function at C10

The NMR spectra of 12 cardenolides with oxygen-containing functions at C10 has been studied. The chemical shifts of the signals of the protons of the C18 angular methyl group, a butenolide ring, and some other protons have been discussed as functions of the structural features of the individual compounds.

Nonclassical Antimetabolites XIX: Simulation of 5′-Phosphoribosyl Binding III. Relative Contribution of Phosphate and the Other Oxygen-Containing Functions to the Binding of the 5′-Phosphoribosyl Moiety to Succinoadenylate Kinosynthetase

The synthesis of 6-mercapto-9H-purine-9-yl-pentanol phosphate (VI) and 9H-adenine-9-yl-pentanol phosphate (VII) <i>via</i> 5-amino-4-chloro-6-(5′-hydroxypentyl-amino)pyrimidine (X) are described. The comparison of VI, VII, thioinosinic acid (III), 5′-adenylic acid (IV), 2′-deoxy-5′-adenylic acid (V), thioinosine (XIII), and adenosine as inhibitors of succinoadenylate kinosynthetase indicated that the twelvefold decrease in activity of VI and VII compared to the ribonucleotides, VII and IV, was due primarily to the removal of the 2′-hydroxyl group and not the 3′-hydroxyl or furanosyl oxygen group of the ribosyl moiety.