共查询到20条相似文献,搜索用时 765 毫秒
1.
2.
Controlled pesticide release from biodegradable polymers 总被引:2,自引:0,他引:2
Anamika Roy Sunil K. Singh Jaya Bajpai Anil K. Bajpai 《Central European Journal of Chemistry》2014,12(4):453-469
Polymers have been widely used in agriculture for applications including controlled release of pesticides and other active ingredients. The ability to predict their delivery helps avoid environmental hazards. Macromolecular matrices used as carriers in controlled release of agricultural active agents, especially pesticides, are reviewed. The review focuses on the advantages and mechanisms of controlled release. It includes biodegradable polymers in agriculture, their manufacturing methods, and their degradation mechanisms and kinetics. The article also presents a critical account of recent release studies and considers upcoming challenges. 相似文献
3.
Kamil Jatczak Mariusz Gruza Katarzyna Filip Piotr Cmoch Grzegorz Grynkiewicz 《Central European Journal of Chemistry》2014,12(12):1222-1231
Protoescigenin, the main aglycone of horse chestnut saponin mixture known as escin, was selected as substrate for exploratory chemistry towards selective protection, followed by propargyl ether formation and subsequent condensation with azido-monosaccharides, to obtain novel triazole linked conjugates of the triterpene. 相似文献
4.
Iryna O. Lebedyeva Sean M. Sileno Kunal Patel Ion Ghiviriga Peter J. Steel Alan R. Katritzky 《Central European Journal of Chemistry》2013,11(6):1019-1022
Amination by organic azides has been carried out to provide aminobarbiturates by fusion of a triazole ring to the 5,6-positions of barbituric acid followed by cleavage and thermal elimination of nitrogen, whereas aza-Wittig reaction gave phosphoranylidene barbituric acid salts. 相似文献
5.
Attila Sipos Antal Udvardy Attila C. Bényei Sándor Berényi 《Central European Journal of Chemistry》2013,11(8):1278-1285
The synthesis of 3-deoxyoripavine (7) was realized as a novel and promising intermediate towards the synthesis of the important class of dopaminergic and/or serotonergic 10-deoxyaporphines and the special pharmacological tool µ opioid antagonist cyprodime. Generally, the preparation of these valuable biologically active compounds was achieved in remarkable yields. 相似文献
6.
Krzysztof Nieszporek Tomasz Banach Przemywslaw Podkościelny 《Central European Journal of Chemistry》2014,12(2):185-193
The Non-Random Two-Liquid activity coefficient model is applied to describe the kinetics of pure gas adsorption on energetically heterogeneous solid surfaces. The surface energetic heterogeneity has been represented by the Gaussian-like function of the adsorption energy distribution. Two different kinetic isotherms have been presented. One of them, determined by using the statistical rate theory, has been critically discussed. The applicability of the presented approach has been demonstrated by a quantitative analysis of two sets of experimental data previously reported in the literature. 相似文献
7.
Pawel Mierczynski Tomasz P. Maniecki Joanna Kaluzna-Czaplinska Ma?gorzata I. Szynkowska Waldemar Maniukiewicz Magdalena Lason-Rydel Wojciech K. Jozwiak 《Central European Journal of Chemistry》2013,11(2):304-312
Nickel catalysts supported on Na-mordenite were used for paraffin LTP56-H hydroconversion into liquid material as a possible component for engine fuels. The effects of none-catalytic thermal treatment and catalytic conditions-zeolite type and reaction conditions (solvent) on the process of liquefaction of LTP56-H paraffin and physicochemical properties of catalysts were studied. The physicochemical properties of catalytic systems were investigated using XRD, TPR, TPD-NH3 and SEM-EDS methods. 相似文献
8.
Activated carbon obtained from bamboo waste was synthesised and modified with iron (BAC-Fe) and used for the removal of arsenic from aqueous solutions. Two different adsorption models were used for analysing the data. The adsorption capacities were determined for BAC-arsenite, BAC-Fe-arsenite, BAC-arsenate and BAC-Fe-arsenate, with a qmax (μg g?1) of 14.89, 19.19, 22.32 and 27.32 respectively. Adsorption capacity varied as a function of pH and modifications to the sorbent. Adsorption isotherms from an aqueous solution of arsenite and arsenates on activated carbons were determined. These adsorption isotherms were consistent with the Langmuir and Freundlich adsorption models. Adsorption kinetics followed a pseudo-first order rate equation, as did the kinetics for BAC-Fe-arsenite and BAC-Fe-arsenate adsorption. 相似文献
9.
Cesare Achilli Annarita Ciana Maurizio Fagnoni Cesare Balduini Giampaolo Minetti 《Central European Journal of Chemistry》2013,11(2):137-139
Boronic acids and their esters are highly considered compounds for the design of new drugs and drug delivery devices, particularly as boron-carriers suitable for neutron capture therapy. However, these compounds are only marginally stable in water. Hydrolysis of some phenylboronic pinacol esters is described here. The kinetics is dependent on the substituents in the aromatic ring. Also the pH strongly influences the rate of the reaction, which is considerably accelerated at physiological pH. Therefore, care must be taken when considering these boronic pinacol esters for pharmacological purposes. 相似文献
10.
C. A. Vasko D. X. Liu E. M. van Veldhuizen F. Iza P. J. Bruggeman 《Plasma Chemistry and Plasma Processing》2014,34(5):1081-1099
The production of \(\hbox {H}_2\hbox {O}_2\) in an atmospheric pressure RF glow discharge in helium-water vapor mixtures has been investigated as a function of plasma dissipated power, water concentration, gas flow (residence time) and power modulation of the plasma. \(\hbox {H}_2\hbox {O}_2\) concentrations up to 8 ppm in the gas phase and a maximum energy efficiency of 0.12 g/kWh are found. The experimental results are compared with a previously reported global chemical kinetics model and a one dimensional (1D) fluid model to investigate the chemical processes involved in \(\hbox {H}_2\hbox {O}_2\) production. An analytical balance of the main production and destruction mechanisms of \(\hbox {H}_2\hbox {O}_2\) is made which is refined by a comparison of the experimental data with a previously published global kinetic model and a 1D fluid model. In addition, the experiments are used to validate and refine the computational models. Accuracies of both model and experiment are discussed. 相似文献
11.
Deniz Altunöz-Erdoğan Nevin Erk Esma Kılıç 《Central European Journal of Chemistry》2013,11(5):706-716
Reboxetine (RBX) electrochemical redox behavior at hanging mercury drop (HMDE) and glassy carbon electrodes (GCE) was studied in various pH Britton-Robinson universal buffers using cyclic voltammetry and square-wave voltammetry. RBX was reduced at the HMDE and oxidized at the GCE with reversible adsorption controlled and irreversible diffusion controlled processes respectively. The anodic peak is due to the amine and the cathodic peak may correspond to oxygen protonation. An oxidation reaction mechanism is proposed. The linear relation between peak currents and RBX concentration allowed simple, sensitive, precise and inexpensive voltammetric procedures to be developed. The limit of detection was 0.04 µM RBX. The procedures were successfully applied to human urine and RBX tablet assay. Therapeutic RBX concentrations in human serum were not detected due to strong drug-protein binding. Using bovine serum albumin, the methods were used to investigate the effect of serum protein binding on RBX determination. 相似文献
12.
Rǎdiţa Aparaschivei Valeriu Şunel Mihaela Holban Marcel Popa Jacques Desbrieres 《Central European Journal of Chemistry》2013,11(11):1808-1815
New potentially biologically active compounds derived from 2-mercapto-benzoxazole were synthesized and coupled on polymeric support of poly (maleic anhydride-alt-vinyl acetate) for the preparation of polymer-drug conjugates with controlled drug release. All compounds were characterized by elemental and spectroscopy (FT-IR, 1H-NMR) analysis. The toxicological tests recommend the products for further laboratory screening. 相似文献
13.
Enantioselective organocatalytic Michael additions affords useful building blocks for many biologically and medicinally relevant compounds. Ionically-tagged diphenylprolinol silyl ether efficiently catalyzes several Michael additions of aldehydes to nitroalkenes in ionic liquids. The Michael additions work well in ionic liquids; yields up to 95% and enantioselectivities up to 95% ee were achieved. Furthermore, in some cases, the catalytic system was reusable. 相似文献
14.
It is important to apply sorbent materials for purification of water from arsenic contamination due to serious arsenic pollution worldwide. We have developed new sorbents based on natural materials that provide a cheap and environmentally friendly alternative. For the first time, peat modified with iron compounds and iron humates were tested for sorption of arsenic compounds. The highest sorption capacity was found in peat modified with iron compounds. We have found that sorption of different arsenic speciation forms was strongly dependent on solution pH, reaction time and temperature. Calculations of the sorption process using thermodynamic parameters indicate the spontaneity of sorption process and its endothermic nature. Sorption kinetics showed that most arsenates are removed within 2 hours, and the kinetics of arsenate sorption on modified peat can be described by the pseudo-second order mechanism. 相似文献
15.
Here we report the transformation of tetracyclic morphinan salutaridine (1) into 2,3,10,11-tetrasubstituted (R)-aporphines. This method serves as another chemical proof of the previously verified biosynthetic connection with pentacyclic morphinan-6,8-diene-type thebaine. In the presence of nucleophiles, this procedure could lead to pharmacologically interesting new tetrasubstituted aporphinoids. The enantioselective synthesis of 7S-salutaridinol (2) has been also achieved in order to investigate the acid-catalyzed reactions of this natural morphinan. 相似文献
16.
Radomir Jasiński Magda Ziółkowska Oleh M. Demchuk Agata Maziarka 《Central European Journal of Chemistry》2014,12(5):586-593
[2+3] Cycloaddition reactions of the highly reactive (Z)-C-(3,4,5-trimethoxyphenyl)-N-methylnitrone with (E)-2-R-nitroethenes proceed under mild conditions and yield mixtures of stereoisomeric 2-methyl-3-(3,4,5-trimethoxyphenyl)-4-nitro-5-R-isoxazolidines. The effect of regiospecificity of the cycloadditions may be accounted for by the theory of electrophilicity indexes. Stereoselectivity, however, is determined by a compilation of steric and secondary orbital effects. 相似文献
17.
Marcin Sajdak 《Central European Journal of Chemistry》2013,11(2):151-159
The aim of this work was to implement a chemometric analysis to detect the relationships between the analysed variables in samples of solid fuels. Efforts are being made to apply chemometrics methods in environmental issues by developing methods for the rapid assessment of solid fuels and their compliance with the required emission characteristics regulations. In the present investigation, two clustering techniques—hierarchical clustering analysis (HCA) and principal components analysis (PCA)—are used to obtain the linkage between solid fuel properties and the type of sample. These analyses allowed us to detect the relationships between the studied parameters of the investigated solid fuels. Furthermore, the usefulness of chemometrics methods for identification of the origin of biofuels is shown. These methods will enable control of the degree of contamination. 相似文献
18.
Teodora E. Harsa Alexandra M. Harsa Beata Szefler 《Central European Journal of Chemistry》2014,12(3):365-376
A novel QSAR approach based on correlation weighting and alignment over a hypermolecule that mimics the investigated correlational space was performed on a set of 40 caffeines downloaded from the PubChem database. The best models describing log P and LD50 values of this set of caffeine derivatives were validated against the external test set and in a new predictive model by using clusters of similarity. 相似文献
19.
Gábor Neumajer Gergő Tóth Szabolcs Béni Béla Noszál 《Central European Journal of Chemistry》2014,12(1):115-125
Novel C3 symmetric tripodal molecules were synthesized from cyclohexane 1,3,5-tricarboxylic acid. Utilizing click and Sonogashira reactions, ion-binding triazole and pyridazin-3(2H)-one units were incorporated to form polydentate ligands for ion complexation. The structures of the novel C3 symmetric derivatives were extensively characterized by 1H, 13C and 2D NMR techniques along with HRMS and IR. The copper(I)-binding potentials of these ligands were investigated by using them as additives in model copper(I)-catalysed azide-alkyne cycloaddition (CuAAC) reactions. The copper(I) complexation ability of our compound was also proved by different spectroscopic methods, such as mass spectrometry, UV and NMR spectroscopy. Based on the mass spectrometric data all of the C3 symmetric ligands formed 1:1 complex with copper(I) ion. The specific role of C3 symmetric polydentate form in the complexation process was also discussed 相似文献
20.
Rui Liu Tonglai Zhang Li Yang Zunning Zhou 《Central European Journal of Chemistry》2014,12(6):672-677
The thermal decomposition of five double-base propellants modified with RDX was studied by dynamic pressure thermal analysis to determine the effect of RDX content (20–60 wt.%) on performance. All have good stability. Both stability and activation energy increase as RDX increases from 20% to 50% then decrease; 50% RDX performs best. The decomposition mechanism is affected by RDX content and temperature. Increasing temperature induces autocatalysis and accelerates decomposition. 相似文献