Presence Of Certain Functional Groups Research Articles

Effect of Ultrasonication Parameters on the Structural, Morphological, and Electrical Properties of Polypyrrole Nanoparticles and Optimization by Response Surface Methodology

Polypyrrole (PPy) nanoparticles are reliable conducting polymers with many industrial applications. Nevertheless, owing to disadvantages in structure and morphology, producing PPy with high electrical conductivity is challenging. In this study, a chemical oxidative polymerization-assisted ultra-sonication method was used to synthesize PPy with high conductivity. The influence of critical sonication parameters such as time and power on the structure, morphology, and electrical properties was examined using response surface methodology. Various analyses such as SEM, FTIR, DSC, and TGA were performed on the PPy. An R2 value of 0.8699 from the regression analysis suggested a fine correlation between the observed and predicted values of PPy conductivity. Using response surface plots and contour line diagrams, the optimum sonication time and sonication power were found to be 17 min and 24 W, respectively, generating a maximum conductivity of 2.334 S/cm. Meanwhile, the model predicted 2.249 S/cm conductivity, indicating successful alignment with the experimental data and incurring marginal error. SEM results demonstrated that the morphology of the particles was almost spherical, whereas the FTIR spectra indicated the presence of certain functional groups in the PPy. The obtained PPy with high conductivity can be a promising conducting material with various applications, such as in supercapacitors, sensors, and other smart electronic devices.

Screening for New Pathways in Atmospheric Oxidation Chemistry with Automated Mechanism Generation.

In the Earth's atmosphere, reactive organic carbon undergoes oxidation via a highly complex, multigeneration process, with implications for air quality and climate. Decades of experimental and theoretical studies, primarily on the reactions of hydrocarbons, have led to a canonical understanding of how gas-phase oxidation of organic compounds takes place. Recent research has brought to light a number of examples where the presence of certain functional groups opens up reaction pathways for key radical intermediates, including alkyl radicals, alkoxy radicals, and peroxy radicals, that are substantially different from traditional oxidation mechanisms. These discoveries highlight the need for methods that systematically explore the chemistry of complex, functionalized molecules without being prohibitively expensive. In this work, automated reaction network generation is used as a screening tool for new pathways in atmospheric oxidation chemistry. The reaction mechanism generator (RMG) is used to generate reaction networks for the OH-initiated oxidation of 200 mono- and bifunctionally substituted n-pentanes. The resulting networks are then filtered to highlight the reactions of key radical intermediates that are fast enough to compete with traditional atmospheric removal processes as well as "uncanonical" processes which differ from traditionally accepted oxidation mechanisms. Several recently reported, uncanonical atmospheric mechanisms appear in the RMG dataset. These "proof of concept" results provide confidence in this approach as a tool in the search for overlooked atmospheric oxidation chemistry. Several previously unreported reaction types are also encountered in the dataset. The most potentially atmospherically important of these is a radical-carbonyl ring-closure reaction that produces a highly functionalized cyclic alkoxy radical. This pathway is proposed as a promising target for further study via experiments and more detailed theoretical calculations. The approach presented herein represents a new way to efficiently explore atmospheric chemical space and unearth overlooked reaction steps in atmospheric oxidation.

Treatment of Real Wastewater from Organic Contaminants by Using Biochar

In a number of water use schemes (water and wastewater treatment), physicochemical treatment methods, in particular adsorption, have been successfully used. However, widespread adoption of these methods is hindered by the high cost of sorbents. One of the promising solutions to these problem of sorption treatment is the use of biochar. Due to its high specific surface area, well-developed porous structure, and surface functionality, biochar has been used as inexpensive adsorbent. The purpose of the laboratory experiments is to determine the sorption properties of biochar obtained from pine – sorption capacity, sorption rate, and purification effect – while removing organic contaminants from real paper mill wastewater. The sorption properties of biochar were studied under static and dynamic conditions, varying the size of the fractions, and processing time. The sorption characteristics of biochar of all the studied fractions were established and it was shown that the most effective sorbent in removing organic contaminants is the 1-biochar’s fraction of (sorption capacity of 11.9 mg of COD per of sorbent). The data obtained enable theoretically substantiate the presence of certain functional groups on the surface of the researched biochar, as well as to develop technological regimes for the treatment of natural and waste waters of a certain composition with its help.

Исследование фосфорсодержащих соединений как противозадирных и противоизносных присадок к трансмиссионным и моторным маслам

Dithiophosphoric acid esters containing various functional groups have been synthesized. On the basis of allyloxybenzyl- and allyloxymethylbenzylchlorides, as well as sodium diisopropyldithiophosphate, allyloxybenzyl- and allyloxymethylbenzyldialkyldithiophosphates were obtained, respectively. 5-methyl-2-hydroxyphenylcarbonylmethyldiisopropyldithiophosphate was synthesized by the interaction of 5-methyl-2-hydroxy-chloroacetophenone and sodium diisopropyldithiophosphate. The synthesized compounds were studied as anti-wear and anti-seize additives for lubricating oils. Were also investigated their thermo-oxidative and anticorrosive properties. It was found that all synthesized compounds provide an improvement in the anti-wear and anti-seize properties of petroleum oils, and the efficiency depends on the presence of certain functional groups in the molecules of additives.

Curcumin analogs: synthesis and biological activities

Curcumin has received great attention in the past three decades due to its versatile medicinal activities, which are attributed to the presence of certain functional groups in its structure. Despite this, the application of curcumin in therapy is limited by its poor aqueous solubility which results in low bioavailability, and also by its low chemical stability due to the keto-enol tautomerism. In this work, eight analogs of curcumin were synthesized starting from aminophenol to tackle these issues. Their chemical structures were characterized by detecting their IR, 1H-NMR, and 13C-NMR spectra. Biological studies were performed on the synthesized analogs using curcumin as a positive control. The tested activities included antioxidant capacity via DPPH and hydroxyl radical scavenging activity tests, preliminary antitumor activity by MTT test against MCF-7 and HeLa cancer cell lines, and antibacterial activity against Haemophilus influenzae, Pseudomonas aeruginosa, Escherichia coli, and Klebsiella pneumonia using disk diffusion technique. The results of antioxidant activity showed that the SC50 values of the synthesized analogs are closely related to the control, the same finding is reported in the preliminary antitumor activity. In the testing of antibacterial activity, the synthesized analogs displayed variable activities with a superior effect attributed to chloride-based analogs. In the course of performing these tests, it could be deduced that both stability and solubility of the analogs were improved in comparison with curcumin. It is proposed that such analogs with improved aqueous solubility may be useful guides to improve the therapeutic applications of curcumin.

The impact of carbon nanotubes on the optical, electrical, and magnetic parameters of Ni2+ and Co2+ based spinel ferrites

Surfactant-assisted co-precipitation method was used to synthesize Ni2+ and Co2+ based spinel ferrite nanoparticles. These ferrites are NiFe2O4, CoFe2O4, and Ni0.4Co0.6Fe2O4. The structural elucidation of the synthesized nanoparticles was carried by X-ray diffraction (XRD) and Fourier-transform infrared spectroscopy (FTIR). Both XRD and FTIR confirmed the spinel structure of prepared ferrite nanoparticles. The Debye-Scherrer equation showed the crystallite size in the range 6–15 nm. This range of particles size is an excellent range for a good signal to noise ratio. XRD result showed that the lattice constant value in Ni0.4Co0.6Fe2O4 decreased with increase in nickel ion concentration. FTIR revealed vibrational frequencies due to the presence of certain functional groups and octahedral and tetrahedral sites of ferrites nanoparticles. Nanocomposites of carbon nanotubes (CNTs) with spinel ferrite nanoparticles were prepared. CNTs influenced the various properties of spinel ferrite nanoparticles. The most affected properties are optical band gap, magnetic properties, dielectric properties, and photocatalytic applications. Ultraviolet–visible spectroscopy was used to study optical properties and photocatalysis. A Tauc plot showed a decrease in nanocomposite band gap values, due to the lower band gap of CNTs. Heterostructures of Ni0.4Co0.6Fe2O4 with carbon nanotubes showed enhanced magnetic behavior and low values of dielectric constant at high-frequency regions due to an increase in cobalt ion concentration. Photocatalytic activity was measured by the degradation of typical organic dye methylene blue (MB). UV–visible spectra of MB in presence of ferrite nanoparticles and their composites showed degradation of MB in visible light irradiation.

BIOSORPTION OF HEAVY METALS FROM THE MULTI-COMPONENT SYSTEMS OF THE GALVANIC INDUSTRY USING BREWER’S GRAIN AS ADSORBENTS

Wastewaters from the galvanization process contain high concentrations of heavy metals representing a great danger to human health as well as to the environment. Heavy metals in the galvanization process are used in the coating process, whereby the coatings of certain metals are formed. The treatment of wastewaters generated by the galvanization process can be conducted by a number of methods, however, today more research is being done on processes which are efficient, economical and cost-effective, but environmentally acceptable. One of those techniques is adsorption. The adsorption process of Cd2+, Ni2+ and Cr2+ions from galvanization water using brewer’s grain as the adsorbent, at different pH values and adsorbent granulation of 0.5 mm is analyzed in this paper. The percentage of moisture and ash was determined, and the FTIR analysis was performed confirming the presence of certain functional groups. Based on the obtained values, it has been shown that the brewer’s grain can be successfully used as a natural adsorbent to remove Cd2+, Ni2+ and Cr2+ ions from galvanization waters, and also that high level of efficiency is obtained at all analyzed pH values. The analysis has also shown that the affinity of adsorbents to Cd2+, Ni2+ and Cr2+ ions is in correlation with physical and chemical properties, but that the best removal efficiency is achieved at the pH 4 value

Изучение сорбции ионов Сe(III) хелатообразующим синтетическим сорбентом на основании сополимера стирола с малеиновым ангидридом и м-аминофенола

In the present article the results of a study for the sorption of cerium (III) ions by a chelating synthetic sorbent are presented. Based on a copolymer of styrene with maleic anhydride and m-aminophenol, a new polymer chelating sorbent was synthesised and its sorption characteristics were studied with respect to cerium (III) ions. The synthesis of the sorbent was carried out in the presence of formalin acting as a crosslinking agent. In the course of the studies, various parameters affecting sorption were determined: optimal pH value; ionic strength; the time of complete sorption equilibrium; the effect of the initial concentration of cerium (III) ions on the sorption process. Studies have shown the maximum sorption capacity of the sorbent with respect to cerium (III) ions to be equal to 540 mg/g at pH = 5. In the course of studying the influence of ionic strength on the sorption process up to a certain value of ionic strength (0.2-1.0 mol/L), the presence of K+ and Clions was established to have no effect on the sorption capacity of the sorbent. The reverse desorption process was also studied and the optimal eluent was established using various mineral acids of the same concentration: 0.5 M solutions of HCl, HNO3, H2SO4 and CH3COOH. HNO3 solution of the 0.5 mol/L concentration demonstrated the best desorption ability with respect to cerium ions. The structure of the synthesised sorbent and the presence of certain functional groups was investigated by IR spectroscopy in the region from 400 to 4000 cm -1 .

Drop-coated reduced-GO thin film as counter electrode in DSSC

In the last decade, many researchers have been proved the role of graphene-based material as counter electrode in dye sensitized solar cell (DSSC) system. One of graphene-based material is reduced graphene oxide (rGO) that have been widely used in optoelectronic devices. Based on it, in this work we prepared the rGO thin films and used as counter electrode (CE) in DSSC with FTO/TiO2/Ru-dye/CE/FTO structure. The rGO thin films were deposited on FTO (Fluorine-doped Tin Oxide) substrates by drop casting technique. The 0.5 and 1.0 mg/ml of rGO powder were dispersed in two kind of solvents which are dimethylformamide (DMF) and l N-methyl-2-pyrrolidinone (NMP) for each concentration. The rGO thin films that produced from two different solvents have a differ visible wavelengths absorbance, although prepared from the same concentration. Form scanning electron microscopy (SEM) observation, the morphology of rGO thin film that prepared using NMP is more homogenous than DMF solvent. This situation may relate to the ability of each solvent in dispersing rGO powder. Fourier Transform Infra-Red spectroscopy was used to identify the presence of certain functional groups both in powder and thin film. The carboxyl group of C-O and C=O is appeared in thin film. The rGO thin film as counter electrode in DSSC was studied from current-voltage (I-V) characteristics. This work revealed that rGO thin film is able to use as alternative counter electrode in Pt-free DSSC since it produced 2.22% in efficiency (under 36.5 mW/cm2 light irradiation).

Prominent Study on Surface Properties and Diffusion Coefficient of Urease-Conjugated Magnetite Nanoparticles.

Herein, the magnetite nanoparticles (MNs) were prepared by facile solvothermal method and its porous nature was modified using 3-(2-aminoethyl)-3-aminopropyl trimethoxysilane (AEAPS). Magnetite formation, successful amino tagging, and urease conjugation on the surface were confirmed from the presence of certain functional groups in Fourier transform infrared (FT-IR) spectra. Also, nanosize (13.2nm) and spherical morphology of MNs were evaluated from diffraction patterns and electron micrographs respectively. Lower retentivity and coercivities in magnetization curve revealed the superparamagnetic behavior, and nitrogen adsorption/desorption curves exhibited decrease in its surface porosity. Conductivity measurements showed lower diffusion coefficient (De = 1.9 × 10-17cm2/min) and higher diffusion with limited hydrolytic reaction in native urease and improved activity of conjugated urease with higher De (12.62 × 10-16cm2/min). Hence, this study revealed that the surface porous nature of MNs can be altered effectively by amino tagging in order to overcome diffusional limitations thereby enhancing enzyme activity.

Predicting optimal finite field strengths for calculating the first and second hyperpolarizabilities using simple molecular descriptors

The finite field method was used to calculate the static first and second hyperpolarizabilities (β and γ) for organic molecules. The dependence of β and γ on the applied electric field strength was investigated and used to determine the optimal field strength for each individual molecule. For γ, we designed a protocol that uses the maximum atomic distance within the molecule along the direction of the applied field to estimate optimal field strengths. However, β is nearly independent of the descriptors we considered, and largely depends on the composition (e.g., the presence of certain functional groups) of the molecule.

Correlation between Frequency and Sound Absorption Coefficient of Polymer Reinforced Natural Fibre

Aspect ratio which is the ratio between the length and diameter of the fiber affects the sound absorption performance of the polymer reinforced natural fiber (ramie or bamboo fiber). The aim of this study is to choose the specific frequency –which is important for industrial application- to obtain an optimal sound absorption coefficient (α) by designing a certain aspect ratio.The acoustic was measured using impedance tube of The ASTM E- 1050=98 standard. Fiber length was 10 mm, while the diameter of the fiber was measured by using a digital optical microscope measurement with an average diameter of 110.4 microns. The morphology of the material was observed by using scanning electron microscope (SEM). Fourier Transform Infrared (FTIR) spectroscopy was used to identify the presence of certain functional groups in a molecule. The results indicated that the average of the sound absorption coefficient of the polymer reinforced ramie fiber reached 0,836 at low frequency of 125 Hz and 0,537 at medium frequency of 1000 Hz, and aspect ratio of 90, while the sound absorption coefficient of the polyester material reinforced bamboo fiber reached 0.973 at medium frequency of 1000 Hz.

Similarities in Kinetic Energy Distributions of Associative Fragments during Dissociative Ionization of Organic Molecules

We have performed a study of the formation of H+2 and H + 3 ions during dissociative ionization of various organic molecules under single collision conditions. The reactions are brought about by electron impact and are observed by multiparticle coincidence momentum imaging. We investigate how the presence of certain functional groups in the molecule is reflected in the kinematics of associative reactions.

Characterization of refractory organic substances by NEXAFS using a compact X-ray source

PurposeWe present the characterization of environmental samples using near-edge X-ray absorption fine structure (NEXAFS) spectra recorded with an in-house device. We want to point out the feasibility of such an easily accessed complementary technique, if not sometimes alternative to NEXAFS studies performed with synchrotron radiation, as the number of compact setups is increasing.Materials and methodsThe experiments were carried out using a laser-driven plasma source. We studied heterogeneous samples like refractory organic substances to demonstrate the potential of NEXAFS spectra, achieved by such an instrument, concerning specimens of high chemical complexity.Results and discussionFrom the respective resonance peaks in the spectra, the presence of certain functional groups, such as aromatic or carbonyl groups, is verified, and the elemental composition is estimated. The results of the reference samples are consistent with the literature. For the environmental samples, external influences of the extraction solvent or fertilizers can be determined from the spectra.ConclusionsThis could provide the possibility to perform test experiments with samples, which are later studied in more detail with synchrotron light and might as well give an impulse on the broader spread of the application of NEXAFS spectroscopy.

Structure pre-requisites for isoflavones as effective antibacterial agents

Recent reports reveal that there is increasing incidence of infections of multidrug-resistant bacteria, including methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant enterococci (VRE). Flavonoids and related compounds have been shown to possess potent antimicrobial activities. Most of the flavonoids are considered as constitutive antimicrobial substances recently termed as “Phytoanticipins,” especially those belonging to prenylated flavonoids and isoflavones. The current review highlights the structure prerequisites for isoflavones as antibacterial agents. Structure–activity relationship (SAR) conclusions have been drawn by comparing the reported minimum inhibitory concentration values for the various isoflavones against S. aureus and MRSA. There exists a significant co-relationship between the presence of certain functional groups (prenyl group, phenolic hydroxyl) at particular positions and antibacterial activity of the compounds. These trends have been postulated with a view of assisting better drug designing of future next-generation antiinfectives, particularly against the bothersome multidrug-resistant microbes. The SAR of these isoflavones has also proved to be a basis to explore the mechanism of antibacterial action. Thus, the study would prove extremely useful to synthesize antibacterial isoflavones in future, which would eventually be beneficial for optimizing the lead molecule for the antibacterial action

Molecular dynamics study of specific interactions in grafted polypropylene organomodified clay nanocomposite

Abstract A molecular dynamics study was performed to analyze the interaction energy between an organomodified clay surface and functionalized polypropylene. A supercell containing montmorillonite with a cation exchange capacity of 140 meq/100 g organomodified with octadecyldimethyl 2-ethylhexyl ammonium and four polymer chains of 25 repeating units length was constructed. According to our results, pure polypropylene shows favorable interactions with organomodified clay surface. Theses interactions are improved in the presence of certain functional groups. The best improvement is obtained with maleic anhydride. Such result is actually in agreement with experimental data.

Analysis of fresh triterpenoid resins and aged triterpenoid varnishes by high-performance liquid chromatography–atmospheric pressure chemical ionisation (tandem) mass spectrometry

Fresh triterpenoid (dammar and mastic) resins and aged triterpenoid varnishes were analysed by on-line HPLC–MS using atmospheric pressure chemical ionisation (APCI). Twenty components were identified in the fresh resins [dammarenolic acid, ursonic acid, oleanonic acid, hydroxydammarenone (I and II), dammaradienol, oleanonic aldehyde, dammarenediol, ursonic aldehyde, oleanolic aldehyde, ursolic aldehyde, hydroxyhopanone, dammaradienone, moronic acid, (3 l,8 R)-3,8-dihydroxypolypoda-13 E,17 E,21-triene, (8 R)-3-oxo-8-hydroxypolypoda-13 E,17 E,21-triene, masticadienonic acid, isomasticadienonic acid, 3- O-acetyl-3-epimasticadienolic acid and 3- O-acetyl-3-epiisomasticadienolic acid]. Analysis of the aged varnishes revealed the presence of some oxidised triterpenoid components [11-oxo-oleanonic acid, 11-oxo-oleanonic acid, 3-oxo-25,26,27-trinordammarano-24,20-lactone, 20,24-epoxy-25-hydroxy-3,4-seco-4(28)dammaren-3-oic acid and some ocotillone type molecules]. Most constituents of these complex samples were well resolved by reversed-phase HPLC. APCI-MS provides useful information about the molecular mass and the presence of certain functional groups. Specific marker compounds were found, which enable the discrimination between aged dammar and mastic varnishes by HPLC–APCI-MS. The fragmentation behaviour of triterpenoids under APCI conditions was compared to that under electron impact conditions. Mass spectrometric fragmentation of triterpenoids with a saturated ring system is straightforward. Triterpenoids with an unsaturation in the ring system probably give rise to double bond migration. Subsequent low energy MS–MS analysis does not provide more structural information, since mainly non-specific ring fragment ions are formed.

P450 enzymes. Inhibition mechanisms, genetic regulation and effects of liver disease.

Multiple hepatic P450 enzymes play an important role in the oxidative biotransformation of a vast number of structurally diverse drugs. As such, these enzymes are a major determinant of the pharmacokinetic behaviour of most therapeutic agents. There are several factors that influence P450 activity, either directly or at the level of enzyme regulation. Drug elimination is decreased and the incidence of drug interactions is increased when there is competition between 2 or more drugs for oxidation by the same P450 enzyme. The available knowledge concerning the relationship between the presence of certain functional groups within the drug structure and inhibition of P450 activity is increasing. In many instances, it is possible to associate inhibition with certain drug classes, e.g. antimycotic imidazoles and macrolide antibiotics. Disease states, especially those with hepatic involvement, and the genetic makeup of the individual are conditions in which some P450s may be downregulated (that is, the enzyme concentrations in liver are decreased), with associated slower rates of drug elimination. In these individuals, dosages of drugs that are substrates for downregulated P450s should be decreased. Exposure to environmental pollutants as well as a large number of lipophilic drugs can result in induction (upregulation) of P450 enzyme activity. This raises the issue of previous approaches to the study of P450 induction in vivo. The use of human hepatocyte preparations in culture is a promising new direction that could assist the determination of modifications to drug therapy necessitated by exposure to inducing agents. Until such information is obtained, however, the use of drugs known to increase the microsomal expression of particular P450s, and increase associated drug oxidation capacity in humans, should be used with caution.

Binding of C-terminal segments of neuropeptide Y to chicken brain.

The C-terminal pentapeptide amide segment of neuropeptide Y (NPY) binds specifically to chicken brain membrane preparations. The contribution of each residue of the C-terminus to this binding has been investigated through the synthesis and evaluation of a series of pentapeptide analogs. The binding of these molecules is strongly dependent on the presence of certain functional groups, in particular the guanidinium group of Arg-35 and the C-terminal aromatic amide function. The significance of these results for the binding to chicken brain tissue of NPY, pancreatic polypeptide and other potentially related neuropeptides is discussed.

A review of the genotoxicity of food, drug and cosmetic colours and other azo, triphenylmethane and xanthene dyes

The genetic toxicology of the major dyestuffs used in foods, drugs and cosmetics has been reviewed. Published data for azo, triphenylmethane and xanthene dyes from short-term assays for muta-carcinogenicity have been summarized and discussed according to usage, current and previous worldwide legislative status. Certain other synthetic food dyes, commercial mixtures, natural and polymeric colourants as well as a section on aminoazobenzene and its derivatives have been included. Genotoxicity has been discussed with reference to structural chemistry, levels of exposure, absorption and metabolism and to epidemiological information. The extent of agreement between data from different tests and correlations with animal cancer assays have been considered. Synthetic dyes from the 3 major structural classes exhibit genotoxicity, whilst only 2 natural colours have proved active. Activity may be due to the presence of certain functional groups, notably nitro- and amino-substituents which are metabolized to ultimate electrophiles that may be stabilized by electronic interaction with aryl rings. Metabolic processes such as azo-reduction may be activating or detoxifying. The low but significant correlation between animal carcinogenicity and short-term test data may be increased with further screening, especially involving chromosome assays. It is suggested that a human cancer hazard may exist where significant quantities of finished benzidine dye samples are handled. Such risks from exposures to other colours and the possibility of human germ-line mutation induction by dyestuffs cannot be meaningfully assessed.