Filtry
wszystkich: 4204
wybranych: 2724
-
Katalog
- Publikacje 2724 wyników po odfiltrowaniu
- Czasopisma 18 wyników po odfiltrowaniu
- Konferencje 6 wyników po odfiltrowaniu
- Osoby 51 wyników po odfiltrowaniu
- Projekty 3 wyników po odfiltrowaniu
- Kursy Online 21 wyników po odfiltrowaniu
- Wydarzenia 5 wyników po odfiltrowaniu
- Dane Badawcze 1376 wyników po odfiltrowaniu
Filtry wybranego katalogu
wyświetlamy 1000 najlepszych wyników Pomoc
Wyniki wyszukiwania dla: SOLVENT-FREE SYNTHESIS
-
Microextraction by packed sorbent: Uncommon detection techniques, sorbents, samples and analytes
PublikacjaAmong sample preparation approaches, the most desirable are procedures that ensure high efficiency and reproducibility, that are cheap, fast and simple, that minimize the number of operational steps and that require a small amount of sample and solvent and are thus environmentally friendly. Microextraction by packed sorbent (MEPS) is a miniaturized form of solid-phase extraction, the use of which has been continuously expanding...
-
Surfactants application in sample preparation techniques: Insights, trends, and perspectives
PublikacjaSince the implementation of Green Chemistry into analytical practice, significant efforts have been made to improve the sustainability of chemical analysis. These include reducing the use of hazardous chemicals and solvents, minimizing waste, and improving energy efficiency. Surfactants can be applied in chemical analysis as an environmentally friendly alternative to conventional solvents and chemicals. The use of surfactants can...
-
Metrics for green analytical chemistry
PublikacjaGreen analytical chemistry, although not being a new concept, does not have a greenness metrics system. Green chemistry metrics are not suitable for analytical procedure assessment because they often refer to the mass of the product. Some efforts have been made to develop suitable metrics for analytical chemistry. Some are simple to use but do not cover all aspects of analytical methods’ environmental impact. Others are more comprehensive...
-
Tmscl as a rate accelerating additive in acylations of amines with 5-(α-amino- α'-hydroxy)methylene meldrum's acids
PublikacjaAspects are presented of the acylation of amines, alcohols and thiols with 5-(α-amino- α'-hydroxy)methylene Meldrum's acids. We placed special emphasis on the acylation reaction of secondary amines with 5-(α-amino- α'-hydroxy)methylene Meldrum's acids, which, due to their basicity, caused problems concerning salt formation with a Meldrum acid derivative. We found that secondary amines, which react at the slowest rate and with a...
-
New procedure for the examination of the degradation of volatile organonitrogen compounds during the treatment of industrial effluents
PublikacjaWe present a new procedure for the determination of 32 volatile organonitrogen compounds in samples of industrial effluents with a complex matrix. The procedure, based on dispersive liquid–liquid microex-traction followed by gas chromatography with nitrogen-phosphorus and mass spectrometric detection, wasoptimized and validated. Optimization of the extraction included the type of extraction and disperser sol-vent, disperser solvent...
-
<i>N,N,N</i>-Trimethyl-N-(methyl 5-deoxy-2,3-<i>O</i>-isopropylidene-β-D-ribofuranosid-5- yl)ammonium 4-methylbenzenesulfonate sesquihydrate.
PublikacjaThe structure of the title compound, [C12H24NO4][C7H7O3S]·1.5H2O, contains alternating layers parallel to (001) of hydrophobic and polar character, stabilized by C-H...O hydrogen bonding. The furan ring adopts an envelope conformation with the C(OMe) atom as the flap, and the dioxolane ring is twisted about one of the O-C(methine) bonds. A comparison to related compounds is presented. The tosylate-O atoms were disordered over two...
-
Application of additional factors supporting the microextraction process
PublikacjaDue to the fact that green analytical chemistry is of high importance, the past two decades have witnessed a rapid growth in the sample preparation area with special emphasis on simplification, miniaturization and automation of extraction procedures. In addition, to accelerate the extraction processes and to improve the separation of analytes, several enhanced parameters are applied. These factors include, ultrasounds, microwaves,...
-
Determination of thiocyanate as a biomarker of tobacco smoke constituents in selected biological materials of human origin
Publikacjan order to protect human health, it is necessary to biomonitor toxic substances originating from tobacco smoke in biological materials sampled from persons with different exposures to tobacco smoke constituents. Thiocyanate anion is a biomarker of exposure to tobacco smoke components which is characterized by a relatively long half‐life in the human body, i.e. 6 days. In this work, we present the results of thiocyanate determinations...
-
Redox property switching in MOFs with open metal sites for improved catalytic hydrogenation performance
PublikacjaIn this study, a decompression-thermalization strategy was utilized for a Cu-containing metal-organic framework (MOF) to tune its redox and catalytic hydrogenation properties. Remarkably, at just 120 °C, open metal sites (OMSs) were successfully constructed by removing coordinated solvent molecules to generate the daughter MOF-120. The tailored redox property of MOF-120 is correlated with the presence of OMSs. Compared with the...
-
Monetary values estimates of solvents emissions
PublikacjaThe impact values for environmental emissions of 52 solvents are estimated and expressed in monetary units. The impact values of solvents present in the air are calculated on the basis of 13 impact indicators and for solvents present in water on additional 2 impact indicators. These impact values are weighted with the results obtained with multi-compartment distribution model, allowing to calculate the fraction of solvent emitted...
-
The hydration properties of protein stabilizer, trimethylamine-N-oxide in aqueous solutions of N-methylacetamide – The volumetric and compressibility studies between 288.15 and 308.15 K
PublikacjaApparent molar volumes and apparent molar isentropic compressions of the protein stabilizer, trimethylamine-N-oxide (TMAO) were determined from the densities and speed of sound measured at T = (288.15, 298.15 and 308.15) K in aqueous solutions of N-methylacetamide (NMA) at four different concentrations (2, 4, 6 and 8 mol/kg). The concentration dependencies of the calculated quantities extrapolated to the infinite dilution lead...
-
S-thioacyldithiophosphates in the synthesis of thiohydroxamic acids and O-thioacylhydroxylamines
PublikacjaDitiofosforany tioacylu to trwałe, łatwo osiągalne z kwasów karboksylowych środki tioacylujące. Z powodu ich niskiej reaktywności wobec nukleofili tlenowych i wysokiej wobec nukleofili azotowych znalazły zastosowanie w syntezie kwasów tiohydroksamowych bezpośrednio z hydroksyloamin z niechronioną grupą hydroksylową. W przypadku dużej zawady przestrzennej można otrzymać O-tioacylohydroksyloaminy.
-
Fe local structure in Pt-free nitrogen-modified carbon based electrocatalysts: XAFS study
PublikacjaThe paper presents a new results on the bonding environment (coordination number and geometry) and on oxidation states of Fe in nitrogen-modified Fe/C composites used as Pt-free catalysts for oxygen reduction in Direct Hydrogen Fuel Cells. Starting from glucose or fructose, two catalysts displaying different electrochemical performance were prepared and studied in the form of pristine powder and thin catalytic layer of electrode...
-
DETERMINATION OF SURFACTANTS IN ENVIRONMENTAL SAMPLES. PART II. ANIONIC COMPOUNDS
PublikacjaSurfactants (SAA) with negative charge of polar group are named as anionic compounds. They are main constituent of most products containing synthetic surfactants. The linear alkylbenzene sulfonates (LAS), alkyl ethoxysulfates (AES) and alkyl sulfates (AS) are typically applied from this class of compounds. Those surfactants are ingredients of household detergents and cleaners, laundry detergents, cosmetic. Moreover they can be...
-
Modified nanodiamond particle size studies by means of dynamic light scattering technique
PublikacjaThe Methods Utilizing the Phenomena of Light Scattering to Measure Particle Size distribution in different solvent, such as deionise water and alcohol and also to study the various structural formation when nanodiamond solution is placed on silicon surface. The purpose of this research project is divided into two parts to configure the measurement units for examining modified nanodiamond particles, examination...
-
Modified nanodiamond particle size studies by means of dynamic light scattering technique
PublikacjaThe Methods Utilizing the Phenomena of Light Scattering to Measure Particle Size distribution in different solvent, such as deionise water and alcohol and also to study the various structural formation when nanodiamond solution is placed on silicon surface. The purpose of this research project is divided into two parts to configure the measurement units for examining modified nanodiamond particles, examination...
-
Smartphone-based digital image colorimetry for the determination of total capsaicinoid content in chili pepper extracts
PublikacjaA simple smartphone-based digital image colorimetry was proposed for the determination of total capsaicinoid content and the assessment of chili pepper pungency. The biobased solvent D-limonene was used for the first time to isolate analytes. Capsaicinoids were efficiently separated from chili pepper by solid-liquid extraction with D-limonene followed by partitioning of the analytes into the ammonium hydroxide solution to eliminate...
-
Bisphenols and their derivatives in baby diaper samples.
PublikacjaMany common products contain and leach hazardous chemicals, including endocrine-disrupting chemicals such as bisphenols that are harmful to human health. For toddlers, this dangerousness is higher because of their not fully developed detoxification system. Due to this, bisphenols content in products such as baby diapers, should be monitored. Baby diapers not only remain in close contact with the skin, but are also used from the...
-
EXAMINATION OF SOL-GEL DERIVED HYDROXYAPATITE ENHANCED WITH SILVER NANOPARTICLES USING OCT AND RAMAN SPECTROSCOPY
PublikacjaHydroxyapatite (HAp) has been attracting widespread interest in medical applications. In a form of coating, it enables to create a durable bond between an implant and surrounding bone tissues. With addition of silver nanoparticles HAp should also provide antibacterial activity. The aim of this research was to evaluate the composition of hydroxyapatite with silver nanoparticles in a non-destructive and non-contact way. For control measurements...
-
Chitin and derivative chitosan-based structures — Preparation strategies aided by deep eutectic solvents: A review
PublikacjaThe high molecular weight of chitin, as a biopolymer, challenges its extraction due to its insolubility in the solvents. Also, chitosan, as the N-deacetylated form of chitin, can be employed as a primary material for different industries. The low mechanical stability and poor plasticity of chitosan films, as a result of incompatible interaction between chitosan and the used solvent, have limited its industrialization. Deep eutectic...
-
Solvation of ionic liquids based on N -methyl- N -alkylmorpholinium cations in N,N -dimethylformamide and N,N -dimethylacetamide – Volumetric and compressibility studies
PublikacjaDensity and sound velocity of the solutions of ionic liquids based on N-alkyl-N-methyl- morpholinium cations: N-ethyl- -methylmorpholinium bis(trifluoromethanesulfonyl)imide, N-butyl-Nmethylmorpholinium bis(trifluoromethanesulfonyl)imide, N-octyl-N-methyl -morpholinium bis(trifluor omethanesulfonyl)imide and N-decyl-N-methylmorpholinium bis(trifluoromethanesulfonyl)imide in N, N-dimethylformamide and N,N-dimethylacetamide were...
-
Interactions between hydration spheres of two different solutes in solution: The least squares fitting with constraints as a tool to determine water properties in ternary systems
PublikacjaBiological systems are complex and the problem of their description lies in mutual interactions between their components. This paper is focused on model experiment-based studies which can reduce these difficulties. The ternary aqueous N-methylacetamide (NMA)–Na2HPO4 system has been studied by means of the FTIR spectroscopy. A novel difference spectra method aimed to extract the spectral contribution of water affected simultaneously...
-
The Metal-Free Regioselective Deuteration of 2-Methylquinolin-8-ol and 2,5-Dimethylquinolin-8-ol, Spectroscopic and Computational Studies
PublikacjaAbstract: Aim and Background: Introducing deuterium to a molecule is of interest to a wide variety of research, including investigation of reaction mechanisms or kinetics, analysis of drug metabolism, structural elucidation of molecules, and syntheses of isotopically labeled materials used for NMR spectroscopy and medicinal research. Objective: The transition-metal-free regioselective deuteration of 2-methylquinolin-8-ol...
-
Determination of free tyrosine in equestrian supplements by LC–MS/MS and comparison of its quantity with total free amino acids content in view of doping control
PublikacjaThe reports on the probable beneficial impact of tyrosine (TYR) supplementation on performance enhancement have contributed to the growth of interest in TYR in equestrian sports field and related industries, such as the manufacture of dietary and nutritional supplements. In this study, the first attempt to the assessment of horses exposure to TYR during nutritional supplementation was demonstrated by quantification of unbound TYR...
-
Free convection of water-Al2O3 nanofluid from horizontal porous coated tube
PublikacjaThe main aim of the present study was to investigate the influence of nanoparticles on heat transfer coefficients during free convection of water-Al2O3 nanofluid from horizontal porous coated tube under atmospheric pressure for nanoparticle concentration of 0.01% by weight. Contrary to published data present study concerns on free convection of nanofluids in extensive, quiescent fluid.
-
The Opening of Central and Eastern European Countries to Free Trade: A Critical Assessment
PublikacjaThree decades after the fall of the Berlin wall and one and a half decades after the Big Bang enlargement of the European Union (2004-2007), we revisit contrasting narratives about the benefit of both free trade and the EU enlargement for Central and Eastern European (CEE) countries. We distinguish old, pre-2004 EU countries from CEE countries that joined the EU in 2004-2007, as well as from the CEE countries that have not become...
-
Extending loophole-free nonlocal correlations to arbitrarily large distances
PublikacjaQuantum theory allows spatially separated observers to share nonlocal correlations, which enable them to accomplish classically inconceivable information processing and cryptographic feats. However, the distances over which nonlocal correlations can be realized remain severely limited due to their high fragility to noise and high threshold detection efficiencies. To enable loophole- free nonlocality across large distances, we introduce...
-
Novel Analytic-Numerical Model of Free Convection: with Leading Edge Considered
PublikacjaA novel solution of the free convection boundary problem is represented in analytical form for velocity and temperature for an isothermal vertical plate, as an example. These fields are built as a Taylor Series in the x coordinate with coefficients as functions of the vertical coordinate (y). We restrict ourselves by cubic approximation for both functions. The basic Navier-Stokes and Fourier-Kirchhoff equations and boundary conditions...
-
Synthesis and reactivity of O-acyl selenophosphates
PublikacjaThe synthesis of several new O-acyl selenophosphates were investigated. The stability and reactivity of the products were studied and related to their structure.
-
Recent Developments in the Synthesis of Unsymmetrical Disulfanes (Disulfides). A Review
PublikacjaThe synthesis of unsymmetrical disulfanes is an important transformation in organic synthesis and medicinal chemistry. The current review is intended to summarize achievements in the synthesis of unsymmetrical disulfanes over the last decade (2004–2014).
-
Optimization of Graphene Oxide Synthesis and Its Reduction
PublikacjaIn this article, we present the review of the chemical methods of synthesis of graphene oxide and its reduction in order to obtain the so-called reduced graphene oxide (rGO) whose properties are similar to those of pure graphene. We also present our experiments and the results in this field and the comparison of the efficiency of different methods of synthesis as well as the reduction of graphene oxide. To characterize the obtained...
-
Reactive extrusion of biodegradable aliphatic polyesters in the presence of free-radical-initiators: A review
PublikacjaNowadays, growing attention is being paid to the environment and sustainability, what fully justified research works focused on modification of biodegradable polymers and their composites. In this field of research reactive extrusion seems to be the most promising approach, which fits well to sustainable development strategy. In In the present work, the in-situ modification of biodegradable aliphatic polyesters and the compatibilization...
-
Modifications of total synthesis of mycophenolic acid
PublikacjaThe total synthesis of mycophenolic acid (MPA), a potent immunosuppressant, was modified. The obtained mycophenolic acid was suitable for further preparation of new prospective immunosuppressants with improved therapeutic properties.
-
Effectiveness of various types of coating materials applied in reinforced concrete exposed to freeze–thaw cycles and chlorides
PublikacjaThis study assesses the durability of coated and uncoated concrete surfaces protected with four different coating materials: water-soluble (BW), solvent-based (BR), mineral (MI), and epoxy (EP). The durability assessment includes evaluating the absorption rate of water, pull-off adhesion strength, and coating material thickness. Concrete samples were subjected to immersion in regular water and a 7% urea solution, followed by...
-
Coordination polymers and molecular structures among complexes of mercury(II) halides with selected 1-benzoylthioureas
PublikacjaSix new 1-benzoyl-3-phenylthiourea and 1-benzoyl-3-(2-methylphenyl)thiourea complexes of mercury( II) were obtained in the reactions of the ligands with HgX2 in methanol (X = Cl, Br, I). Their structures, determined by single-crystal X-ray diffraction analysis, exhibit different stoichiometries and molecular organization. Coordination centers adopt more or less distorted tetrahedral geometry (five structures) or distorted trigonal...
-
Investigating COVID-19 active pharmaceutical ingredients (APIs) degradation using Peroxydisulfate/FeMnOx binary metal oxide/Ultrasound System
PublikacjaDegradation of Favipiravir using a hybrid system of peroxydisulfate, FeMnOx binary metal oxide, and ultrasound irradiation was studied. A novel catalyst was synthesized with deep eutectic solvent (DES). The effects of DES type on catalytic performance was evaluated and the catalysts were characterized using XRD, SEM, BET, XPS, and EDS. DES-based catalysts exhibited higher efficiency due to structure change, surface area enhancement...
-
Optimization of a Fabric Phase Sorptive Extraction protocol for the isolation of six bisphenols from juice pouches to be analysed by high performance liquid chromatography coupled with diode array detector
PublikacjaFabric Phase Sorptive Extraction (FPSE) combined with high pressure liquid chromatography using to diode array detection (HPLC-DAD) was applied for the simultaneous determination of bisphenols (BPA, BPB, BPC, BPE, BPF, BPS) in juice pouches. The FPSE procedure was optimized with regards to the critical parameters that affect the performance of the method including the selection of the FPSE membrane type and size, adsorption time,...
-
Effectiveness of various types of coating materials applied in reinforced concrete exposed to freeze–thaw cycles and chlorides
PublikacjaThis study assesses the durability of coated and uncoated concrete surfaces protected with four Different coating materials: water-soluble (BW), solvent-based (BR), mineral (MI), and epoxy (EP). The durability assessment includes evaluating the absorption rate of water, pull-of adhesion strength, and coating material thickness. Concrete samples were subjected to immersion in regular water and a 7% urea solution, followed by cyclic...
-
Efficient optimization approaches for microwave assisted extraction of high-quality antioxidant compounds from Salvia officinalis L.: UHPLC-HRMS differential analysis of phenolic profiles obtained by ultrasound and microwave extraction
PublikacjaThe study aims to optimize MAE of total phenolic compounds (TPC) and antioxidant capacity from Salvia officinalis L. leaves using a definitive screening design (DSD) and I-optimal design. UHPLC-HRMS analysis was used to identify and compare the composition of MAE and UAE optimal extracts. The results showed that DSD and I-optimal design were successfully applied for the optimization of MAE targeting phenolics and other antioxidants...
-
Thermochemistry of rare earth perovskites Na3xRE0.67−xTiO3 (RE = La, Ce)
PublikacjaHigh-temperature oxide melt solution calorimetry using sodium molybdate (3Na2O·4MoO3) solvent at 973 K was performed for the Na3xRE0.67−xTiO3 (RE = La, Ce) perovskite series. The enthalpies of formation of lanthanum perovskites from oxides (La2O3, Na2O, TiO2), are −107.25 ± 2.56, −93.83 ± 6.06, −80.68 ± 5.93, and −33.49 ± 4.26 kJ/mol and enthalpies of formation from elements are −1614.05 ± 5.37, −1596.44 ± 7.68, −1594.03 ± 7.58,...
-
The importance of the shape of the protein–water interface of a kinesin motor domain for dynamics of the surface atoms of the protein
PublikacjaA single kinesin motor domain immersed in water has been investigated using molecular dynamics. It has been found that local properties of water in the solvation shell change along with the nature of the neighboring protein surface. However, a detailed analysis leads to the conclusion that the geometrical features of hydrogen bonds and overall structure of kinesin hydration water are not very different from bulk water. The local...
-
Aggregation of imidazoacridinones - spectroscopic and microcalorimetric approach
PublikacjaImidazoacridinones (IA) belong to a group of polycyclic heteroaromatic antitumor compounds. IA create the aggregated form in water solution. Self-association of substances is a very important phenomenon in many fields of applied chemistry. It is also fundamental model reaction of many kinds of molecular interactions such as the micelle formation of amphiphilic substances and the binding of small organic molecules to macromolecules....
-
Porosity and swelling properties of novel polyurethane–ascorbic acid scaffolds prepared by different procedures for potential use in bone tissue engineering
PublikacjaIn this work, a novel polyurethane (PU) system based on poly(ethylene-butylene) adipate diol, 1,6-hexamethylene diisocyanate, 1,4-butanediol, and ascorbic acid was used to prepare scaffolds with potential applications in bone tissue engineering. Two fabrication methods to obtain porous materials were chosen: phase separation (PS)/salt particle leaching (PL) and solvent casting (SC)/salt PL. The calculated porosity demonstrated...
-
Engineering Candida albicans glucosamine-6-phosphate synthase for efficient enzyme purification
PublikacjaRationally designed muteins of Candida albicans glucosamine-6-phosphate synthase, an enzyme known as a promising target for antifungal chemotherapy, were constructed, overexpressed in Escherichia coli and purified to near homogeneity. To facilitate and to optimize the purification of the enzyme, three recombinant versionscontaining internal oligoHis fragments were constructed: (i) by substituting residues 343 - 348...
-
The importance of the shape of the protein-water interface of a kinesin motor domain for dynamics of the surface atoms of the protein
PublikacjaSingle kinesin motor domain immersed in water has been investigated using molecular dynamics. It has been found that local properties of water in solvation shell change along with the nature of neighboring protein surface. However, a detailed analysis leads to the conclusion that the geometrical features of hydrogen bonds and overall structure of kinesin hydration water is not very different from bulk water. The local values of...
-
Ultrasound assisted extraction
PublikacjaThe use of green and sustainable extraction techniques is very popular topic in the multidisciplinary area of chemistry, biology and technology. There is no doubt that extraction constitutes a very important step of analytical procedures of separation, detection, identification and determination of wide spectrum analytes from samples characterized by complex and very often nonhomogeneous composition of matrix. Traditional techniques...
-
Chromium‑based metal organic framework for pipette tip micro‑solid phase extraction: an effective approach for determination of methyl and propyl parabens in wastewater and shampoo samples
PublikacjaAbstract Background A chromium-based metal organic framework was synthesized and employed as an efficient sorbent for pipette tip micro-solid phase extraction and preconcentration of parabens from wastewater and shampoo samples up to sub-ppb level before their spectrophotometric analysis. Results Factors affecting preconcentration including volume and type of solvent, amount of sorbent, number of extraction, and volume and pH of...
-
DMSO and TMAO—Differences in Interactions in Aqueous Solutions of the K-Peptide
PublikacjaInteractions between a solvent and their co-solute molecules in solutions of peptides are crucial for their stability and structure. The K-peptide is a synthetic fragment of a larger hen egg white lysozyme protein that is believed to be able to aggregate into amyloid structures. In this study, a complex experimental and theoretical approach is applied to study systems comprising the peptide, water, and two co-solutes: trimethylamide...
-
An improved scalable method of isolating asphaltenes
PublikacjaA new, improved and scalable procedure of asphaltene fraction isolation is presented and compared to standard test methods. The new procedure uses 1:40 feedstock to solvent (n-heptane) ratio (g/mL), filtration through a cellulosic thimble and extensive washing in a Soxhlet type extractor. The group type composition and purity of the asphaltene fractions have been examined using thin-layer chromatography with flame-ionization detection....
-
SURFACTANTS IN KLODNICA RIVER (KATOWICE, POLAND). PART II. QUATERNARY AMMONIUM COMPOUNDS
PublikacjaThe paper presents methods of determination of analytes of the cation group (alkyl benzyl dimethyl ammonium (BDDA-C12-C16), alkyl trimethyl ammonium (TMA), hexadecyl piridinium (HP)) in surface water and bottom sediment samples. In the sample preparation phase the solid phase extraction (SPE) or accelerated solvent extraction/ultrasound assisted extraction (ASE/UAE)-SPE technique was used and in the identification phase and quantitative...