Accuracy and CPU time of JE-TLM,PLRC-TLM and CRC-TLM methods for plasma medium

The current density (JE), the piecewise linear recursive convolution (PLRC) and the constant convolution recursive (CRC) techniques are developed and integrated into the transmission line matrix (TLM) algorithm. A comparison of these three schemes according to the criteria of accuracy and CPU time is presented. Numerical experiments show that JE provides the most accurate solution and requires the least CPU time; PLRC is nearly as accurate but consumes more CPU time than CRC.     

Spectrophotometric Studies of Entrapped Thymol Phtalein pH Indicator into Sol‐Gel Matrix

This research involves the behavior of thymol phtalein pH indicator entrapped into the sol‐gel derived inorganic matrix. The method is based on the physical entrapment of the reagent molecules in the sol‐gel matrix. The immobilized thymol phthalein pH indicator shows behavior similar to its solution counterpart. The UV/vis spectra indicate that the thymol phthalein retains its structure during the sol‐gel reactions in terms of response to pH. Thymol phthalein can be regarded as uniformly distributed in the sol‐gel matrix. This observation has been confirmed using polarized microscopy. This research shows that thymol phtalein can be immobilized in sol‐gel glasses and used as a solid pH sensor.     

Functionalization of the Methyl C(sp3)–H Bond of 2,3-Dimethylquinoxaline with 5-Arylfuran-2,3-diones

Russian Journal of Organic Chemistry - 5-Arylfuran-2,3-diones reacted with 2,3-dimethylquinoxaline to give mono- and bis-C-acylation products,...     

UV dosimeter based on polyamide woven fabric and nitro blue tetrazolium chloride as an active compound

This paper reports on the preparation and features of a UV light dosimeter composed of nitro blue tetrazolium chloride (NBT) and polyamide woven fabric. This textile dosimeter is based on the conversion reaction of NBT into formazan, which was initially examined in aerated aqueous solutions through steady state UV irradiation. Irradiated solutions change their colour as a consequence of the formation of polydisperse NBT formazan particles. This was analysed in relation to the absorbed dose of UV light through UV–VIS spectrophotometry and dynamic laser light scattering measurements. When NBT substrate molecules are embedded in polyamide textile, UV irradiation leads to similar effects as in solution. However, the tinge intensity changes at much lower absorbed doses. The dependence of the tinge intensity on the absorbed dose was followed by measurements of the remission of light from the NBT-polyamide samples. Consequently, the calibration parameters were calculated such as the dose sensitivity, dose range, and quasi-linear dose range. An improvement of the NBT-polyamide samples by application of a colour levelling agent and improvement of their resistance to humidity is presented. Finally, the samples were used for estimation of absorbed UV energy distribution showing their capability as new dosimeters for in-plane high resolution radiation dose measurements.     

Acetylation of cellulose in LiCl-<Emphasis Type="Italic">N,N</Emphasis>-dimethylacetamide: first report on the correlation between the reaction efficiency and the aggregation number of dissolved cellulose

The acylation of three cellulose samples by acetic anhydride, Ac₂O, in the solvent system LiCl/N,N-dimethylacetamide, DMAc (4 h, 110 °C), has been revisited in order to investigate the dependence of the reaction efficiency on the structural characteristics of cellulose, and its aggregation in solution. The cellulose samples employed included microcrystalline, MCC; mercerized cotton linters, M-cotton, and mercerized sisal, M-sisal. The reaction efficiency expresses the relationship between the degree of substitution, DS, of the ester obtained, and the molar ratio Ac₂O/AGU (anhydroglucose unit of the biopolymer); 100% efficiency means obtaining DS = 3 at Ac₂O/AGU = 3. For all celluloses, the dependence of DS on Ac₂O/AGU is described by an exponential decay equation: DS = DS_o − Ae^{−[(Ac2O/AGU)/B]}; (A) and (B) are regression coefficients, and DS_o is the calculated maximum degree of substitution, achieved under the conditions of each experiment. Values of (B) are clearly dependent on the cellulose employed: B_(M-cotton) > B_(M-sisal) > B_(MCC); they correlate qualitatively with the degree of polymerization of cellulose, and linearly with the aggregation number, N_agg, of the dissolved biopolymer, as calculated from static light scattering measurements: (B) = 1.709 + 0.034 N_agg. To our knowledge, this is the first report on the latter correlation; it shows the importance of the physical state of dissolved cellulose, and serves to explain, in part, the need to use distinct reaction conditions for MCC and fibrous celluloses, in particular Ac₂O/AGU, time, temperature.     

In vitro cytotoxic evaluation of some new heterocyclic sulfonamide derivatives

Sulfonamide‐bearing compounds posses many types of biological activities and have been recently reported to show substantial antitumor activity in vitro and/or in vivo. There are a variety of mechanisms for the anticancer activity, and the most prominent mechanism is the inhibition of carbonic anhydrase isozymes. This work reports the synthesis of some new quinoline, pyrimido[4,5‐b]quinoline and 3,1‐oxazinoquinoline derivatives bearing a sulfonamide moiety. All the newly synthesized compounds were evaluated for their in vitro anticancer activity against Ehrlich ascites carcinoma cells. Compounds 10 , 13 , and 26 were the most active compounds with IC₅₀ values of 6.1 μM, 6.8 μM, and 6.4 μM, respectively, and exhibited better activities than the reference drug doxorubicin (IC₅₀ = 68.1 μM). J. Heterocyclic Chem., 2011.     

Free-radical reactions of the tris-dioximate clathrochelates: synthesis and X-ray structure of the first cyclohexyl-substituted monoribbed-functionalized macrobicyclic iron(ii) complex

Quantum chemical calculations were performed at the DFT level for the boron-capped dichloro-substituted tris-dioximate iron(II) clathrochelate and cyclohexane and 1,4-dioxane radicals. The 1,4-dioxane and cyclohexane radicals are nucleophiles towards the macrobicyclic precursor studied. The reaction of this clathrochelate with cyclohexane in the presence of a free-radical initiator resulted in substitution of a chlorine atom by a cyclohexyl fragment. The compound obtained was characterized by elemental analysis, IR spectroscopy, ¹H and ¹³C{¹H} NMR, and single-crystal X-ray diffraction data.     

Synthesis and some transformations of 2-(2-furyl)naphtho[1,2-<Emphasis Type="Italic">d</Emphasis>]oxazole

By condensation of 1-amino-2-hydroxynaphthalene with furoyl chloride in 1-methyl-2-pyrrolidone 2-(2-furyl)naphtho[1,2-d]oxazole was synthesized and brought into electrophylic substitution reactions: nitration, bromination, sulfonation, formylation, and acylation. The substituent commonly was introduced into the position 5 of the furan ring, but at the nitration and bromination electrophilic attack was directed both at the furan ring and the naphthalene fragment.     

A nonlinear oscillatory system subjected to driving forces of elliptic type

The aim of this paper is to show how Jacobi elliptic functions in combination with the averaging and the harmonic balance methods can be applied to obtain the approximate solution of two coupled, ordinary differential equations having a spring with cubic nonlinearity and subjected to driving forces of elliptic type. By an appropriate choice of the system parameter values, it is possible to show that our derived solution represents the exact steady-state solution of the undamped Duffing equation with driving force of elliptic type. At the end of this work, we also demonstrate the validity of our derived solution by comparing the amplitude–time response curves with those of the numerical integration solutions.