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Articles 7801 - 7830 of 10319
Full-Text Articles in Physical Sciences and Mathematics
On Some Algebraic Properties Of Semi-Discrete Hyperbolic Type Equations, İsmagi̇l Habibullin, Asli Pekcan, Natalya Zheltukhina
On Some Algebraic Properties Of Semi-Discrete Hyperbolic Type Equations, İsmagi̇l Habibullin, Asli Pekcan, Natalya Zheltukhina
Turkish Journal of Mathematics
Nonlinear semi-discrete equations of the form t_x(n+1) = f(t(n), t(n+1), t_x(n)) are studied. An adequate algebraic formulation of the Darboux integrability is discussed and an attempt to adopt this notion to the classification of Darboux integrable chains has been undertaken.
On Generalized Solution Of A Class Of Higher Order Operator-Differential Equations, Rovshan Z. Gumbataliev
On Generalized Solution Of A Class Of Higher Order Operator-Differential Equations, Rovshan Z. Gumbataliev
Turkish Journal of Mathematics
In this paper the sufficient conditions on the existence and uniqueness of a generalized solution on the axis are obtained for higher order operator-differential equations, the main part of which is multi characteristic.
Primary Finitely Compactly Packed Modules And S-Avoidance Theorem For Modules, Arwa Eid Ashour
Primary Finitely Compactly Packed Modules And S-Avoidance Theorem For Modules, Arwa Eid Ashour
Turkish Journal of Mathematics
In this paper we introduce the concept of primary finitely compactly packed modules, which generalizes the concept of primary compactly packed modules. We first find the conditions that make the primary finitely compactly packed modules primary compactly packed. Also, several results on the primary finitely compactly packed modules are proved. In addition, the necessary and sufficient conditions for an R-module M to be primary finitely compactly packed are investigated. Finally, we introduce the S-Avoidance Theorem for modules.
A Numerical Solution Of Wave Equation Arising In Non-Homogeneous Cylindrical Shells, Allaberen Ashyralyev, Mehmet Emi̇r Köksal
A Numerical Solution Of Wave Equation Arising In Non-Homogeneous Cylindrical Shells, Allaberen Ashyralyev, Mehmet Emi̇r Köksal
Turkish Journal of Mathematics
A numerical solution of wave equation arising in non-homogeneous cylindrical shells\ is considered. Stable numerical schemes are developed. The stability estimates for the solution of these difference schemes and first and second order difference derivatives are presented. Applying the difference schemes, the numerical methods are proposed for solving the the given initial-boundary value problem.
Radical Anti-Invariant Lightlike Submanifolds Of Semi-Riemannian Product Manifolds, Erol Kiliç, Bayram Şahi̇n
Radical Anti-Invariant Lightlike Submanifolds Of Semi-Riemannian Product Manifolds, Erol Kiliç, Bayram Şahi̇n
Turkish Journal of Mathematics
We introduce radical anti-invariant lightlike submanifolds of a semi Riemannian product manifold and give examples. After we obtain the conditions of integrability of distributions which are involved in the definition of radical anti-invariant lightlike submanifolds, we investigate the geometry of leaves of distributions. We also obtain the induced connection is a metric connection and a radical anti-invariant lightlike submanifold is a product manifold under certain conditions. Finally, we study totally umbilical radical anti-invariant lightlike submanifolds and observe that they are totally geodesic under a condition.
Sufficient Conditions For The Lp-Equivalence Between Two Nonlinear Impulse Differential Equations, A. Georgieva, S. Kostadinov
Sufficient Conditions For The Lp-Equivalence Between Two Nonlinear Impulse Differential Equations, A. Georgieva, S. Kostadinov
Turkish Journal of Mathematics
Sufficient conditions for the Lp-equivalence between two nonlinear impulse differential equations with unbounded linear parts and possibly unbounded nonlinearity parts are given. An example of two nonlinear impulse differential parabolic equations is considered.
On Pseudo-Inverses Of Fredholm Operators, Christoph Schmoeger
On Pseudo-Inverses Of Fredholm Operators, Christoph Schmoeger
Turkish Journal of Mathematics
Suppose that A is a Fredholm operator on a Banach space. We prove that A has index =0 (resp. >= 0, resp. Keywords: Fredholm operator, pseudo-inverse
Essential Spectra Of Composition Operators On The Space Of Bounded Analytic Functions, Uğur Gül
Essential Spectra Of Composition Operators On The Space Of Bounded Analytic Functions, Uğur Gül
Turkish Journal of Mathematics
In this small note we characterize the essential spectra of a class of composition operators on H^{\infty}(H) of the upper half-plane H and on H^{\infty}(D) of the unit disc D. These composition operators are induced by perturbations of translations
Use Of Characteristic Basis Function Method For Scattering From Terrain Profiles, Atacan Yağbasan, Celal Alp Tunç, Vakur B. Ertürk, Ayhan Altintas, Raj Mittra
Use Of Characteristic Basis Function Method For Scattering From Terrain Profiles, Atacan Yağbasan, Celal Alp Tunç, Vakur B. Ertürk, Ayhan Altintas, Raj Mittra
Turkish Journal of Electrical Engineering and Computer Sciences
An integral equation (IE) based solution procedure is presented for the rigorous analysis of scattering from terrain profiles. The procedure uses characteristic basis function method (CBFM), which is hybridized with the forward-backward method (FBM), to reduce the storage requirements of the resultant Method of Moments (MoM) impedance matrix, as well as to accelerate the solution procedure. Numerical results in the form of induced current and scattered field are presented to assess the accuracy and efficiency of the solution procedure.
Comparison Of Rectangular And Cylindrical Fdtd Representations On A Ring Resonator Problem, Funda Akleman, Levent Sevgi̇
Comparison Of Rectangular And Cylindrical Fdtd Representations On A Ring Resonator Problem, Funda Akleman, Levent Sevgi̇
Turkish Journal of Electrical Engineering and Computer Sciences
The aim of this paper is to discuss rectangular and cylindrical representations of finite-difference time-domain (FDTD) method over characteristic tests and comparisons. A ring resonator is chosen as a canonical structure and modeled with both rectangular- and cylindrical-FDTD packages. Calibration against analytical exact solution derived in terms of cylindrical Bessel functions is also performed. It is shown that rectangular-FDTD with periodic boundary condition, where the computation domain is reduced, can also be applied in modeling circular structures.
Biomedical Circuits And Systems Dedicated For Sensing And Neurostimulation: Case Study On Urinary Bladder Dysfunctions, Mohamad Sawan, Aguibou Ba, Faycal Mounaim, Jacques Corcos, Mostafa Elhilali
Biomedical Circuits And Systems Dedicated For Sensing And Neurostimulation: Case Study On Urinary Bladder Dysfunctions, Mohamad Sawan, Aguibou Ba, Faycal Mounaim, Jacques Corcos, Mostafa Elhilali
Turkish Journal of Electrical Engineering and Computer Sciences
This paper covers circuits and systems techniques for the construction of high reliability biosensing and neurostimulation smart medical devices. Such microsystems are dedicated for interconnections through the peripheral neural systems. Case study related to applications such as bladder control is discussed. Available electrical neurostimulation techniques for the rehabilitation of urinary bladder functions do not allow an adequate voiding due to dyssynergia between the bladder and the sphincter. A new implantable stimulator, built with commercially available electronic components, was designed to overcome these difficulties. The proposed system performs two types of stimulations: Selective Stimulation for bladder voiding and Permanent Stimulation to …
Recent Advances In Perfectly Matched Layers In Finite Element Applications, Özlem Özgün, Mustafa Kuzuoğlu
Recent Advances In Perfectly Matched Layers In Finite Element Applications, Özlem Özgün, Mustafa Kuzuoğlu
Turkish Journal of Electrical Engineering and Computer Sciences
We present a comparative evaluation of two novel and practical perfectly matched layer (PML) implementations to the problem of mesh truncation in the finite element method (FEM): locally-conformal PML, and multi-center PML techniques. The most distinguished feature of these methods is the simplicity and flexibility to design conformal PMLs over challenging geometries, especially those with curvature discontinuities, in a straightforward way without using artificial absorbers. These methods are based on specially- and locally-defined complex coordinate transformations inside the PML region. They can easily be implemented in a conventional FEM by just replacing the nodal coordinates inside the PML region by …
Generation Of High-Repetition-Rate Pulses Utilizing Cascaded Single Mode Fiber And Semiconductor Optical Amplifier, Jianwei Wu, Hai-Bo Bao
Generation Of High-Repetition-Rate Pulses Utilizing Cascaded Single Mode Fiber And Semiconductor Optical Amplifier, Jianwei Wu, Hai-Bo Bao
Turkish Journal of Electrical Engineering and Computer Sciences
To generate high-repetition-rate optical pulses, a novel and simple device is demonstrated, in which the cascaded single mode fiber (SMF) with negative third order dispersion and semiconductor optical amplifier (SOA) are adopted. Numerical research results show that let an optical pulse with center wavelength in zero dispersion wavelength of optical fiber transit in SMF for generating an oscillation pulse. Subsequently, the followed SOA is provided for amplification. As a consequence, the high-repetition-rate optical pulses can be obtained.
Synthesis And Characterizations Of Some New 4h-1,2,4-Triazole Derivatives, Nesli̇han Demi̇rbaş, Ahmet Demi̇rbaş, Şule Ceylan, Deni̇z Şahi̇n
Synthesis And Characterizations Of Some New 4h-1,2,4-Triazole Derivatives, Nesli̇han Demi̇rbaş, Ahmet Demi̇rbaş, Şule Ceylan, Deni̇z Şahi̇n
Turkish Journal of Chemistry
3-[(5-Amino-1,3,4-thiadiazol-2-yl)methyl]-4-ethoxycarbonylamino-5-alkyl-4H-1,2,4-triazoles (2a,b) were obtained from the reaction of 3-cyanomethyl-5-alkyl-4-ethoxycarbonylamino-4H-1,2,4-triazoles (1a,b) with thiosemicarbazide in the presence of trifluoroacetic acid. The treatment of the obtained compounds (2a,b) with acetic anhydride for 1 h afforded 3-[(5-acetylamino-1,3,4-thiadiazol-2-yl)methyl]-4-ethoxycarbonylamino-5-alkyl-4H-1,2,4-triazoles (3a,b). The synthesis of 4-ethoxycarbonylamino-3-[(2,3-dihydro-1,3-benzoxazol-2-yl)methyl]-5-(4-methylbenzyl)-4H-1,2,4-triazole (4) was performed by the treatment of 3-[(5-acetylamino-1,3,4-thiadiazol-2-yl)methyl]-4-ethoxycarbonylamino-5-(4-methylbenzyl)-4H-1,2,4-triazole (3a) with o-aminophenol under nitrogen atmosphere for 50 h. The reaction of compounds 1a,b with salicylaldehyde in the presence of sodium ethoxide yielded 2-{4-[(ethoxycarbonyl)amino]-5-alkyl-4H-1,2,4-triazol-3-yl}-3-(2-hydroxyphenyl)-acrylonitriles (5a,b). The acetylations of compounds 5a,b with acetic anhydride for 5 h resulted in the formation of 2-{4-[acetyl(ethoxycarbonyl)amino]-5-alkyl-4H-1,2,4-triazol-3-yl}-3-[2-(acetyloxy)phenyl]-acrylic acids (6a,b). On the other hand, the treatment of compounds 5a,b with …
Synthesis, X-Ray Structure, And Bioassay Of Newly Synthesized Trimethyltin(Iv) 2,3-Methylenedioxy Benzoate, Mukhtiar Hussain, Muhammad Hanif, Saqib Ali, Saira Shahzadi, Helen S. Evans
Synthesis, X-Ray Structure, And Bioassay Of Newly Synthesized Trimethyltin(Iv) 2,3-Methylenedioxy Benzoate, Mukhtiar Hussain, Muhammad Hanif, Saqib Ali, Saira Shahzadi, Helen S. Evans
Turkish Journal of Chemistry
Trimethyltin(IV) complex containing the carboxylate ligand 2,3-methylenedioxybenzoic acid (HL) have been synthesized and characterized in solution state by multinuclear NMR (^1H, ^{13}C and ^{119}Sn) using the noncoordinating solvent and also in solid sate by FTIR, mass spectrometry, and X-ray crystallography. Spectroscopic data have shown that methylenedioxy moiety has not coordinated with tin atom; instead, the coordination site is a -COO group, which is proved by spectral and XRD data. The solid state structure shows the trigonal bipyramidal geometry with a space group P2_1/c. This compound was tested for its in vitro antitumor activity.
Preparation Of 1,5-Diketones By Addition Of Cyclohexanone To Chalcones Under Solvent-Free Phase Transfer Catalyst Condition, Mustafa Ceylan, Hayretti̇n Gezegen
Preparation Of 1,5-Diketones By Addition Of Cyclohexanone To Chalcones Under Solvent-Free Phase Transfer Catalyst Condition, Mustafa Ceylan, Hayretti̇n Gezegen
Turkish Journal of Chemistry
Eight different chalcone-1,5-diketone derivatives (5a-h) were prepared by the reaction of chalcone derivatives (3a-h) with cyclohexanone under the solvent-free phase transfer catalyst condition with modarate to high yields. The mechanistic pathway of the reaction can be explained by the Michael-type addition of cyclohexanone to chalcone derivatives (3a-h).
Synthesis And Characterization Of A Novel Metal Phosphonate, Zirconium (Iv)-Hydroxy Ethylidene Diphosphonate, And Its Application As An Ion Exchanger, Amit Jayswal, Uma Chudasama
Synthesis And Characterization Of A Novel Metal Phosphonate, Zirconium (Iv)-Hydroxy Ethylidene Diphosphonate, And Its Application As An Ion Exchanger, Amit Jayswal, Uma Chudasama
Turkish Journal of Chemistry
A novel hybrid ion exchange material, Zirconium-hydroxy ethylidene diphosphonate [ZrHEDP], of the class of tetravalent metal acid (TMA) salts has been synthesized by the sol-gel technique. The material was characterized with elemental analysis (ICP-AES), thermal analysis (TGA, DSC), and FT-IR and X-ray diffraction studies. The chemical resistivity of the material in various media was evaluated. ZrHEDP was further investigated for its possible use as an ion exchanger. The Na^+ ion-exchange capacity (IEC) of the material was determined, and kinetics and thermodynamics of exchange for the metal ions Cu(II), Ni(II), Zn(II), and Mn(II) towards ZrHEDP were studied. The sorption of the …
New Polyamides Based On Bis(P-Amidobenzoic Acid)-P-Phenylene Diacrylic Acid And Hydantoin Derivatives: Synthesis And Characterization, Khalil Faghihi
New Polyamides Based On Bis(P-Amidobenzoic Acid)-P-Phenylene Diacrylic Acid And Hydantoin Derivatives: Synthesis And Characterization, Khalil Faghihi
Turkish Journal of Chemistry
Bis(p-amidobenzoic acid)-p-phenylene diacrylic acid (6) as a new monomer containing p-phenylenediacryloyl moiety was synthesized by using a 3-step reaction. At first p-phenylenediacrylic acid (3) was prepared by reaction of terephthal aldehyde (1) with malonic acid (2) in the presence of pyridine, and then diacid 3 was converted to p-phenylenediacryloyl chloride (4) by reaction with thionyl chloride. Finally bis(p-amidobenzoic acid)-p-phenylene diacrylic acid (6) was prepared by the condensation reaction of phenylenediacryloyl chloride (4) with p-aminobenzoic acid (5). Then 6 new polyamides (8a-f) containing p-phenylenediacryloyl and hydantoin moiety in the main chain were prepared by the direct polycondensation reaction of bis(p-amidobenzoic acid)-p-phenylene …
Synthesis And Crystal Structure Of Pilloin, Hong-Bing Yang, Yan-Chang Wang, Zun-Ting Zhang, Yong Chang
Synthesis And Crystal Structure Of Pilloin, Hong-Bing Yang, Yan-Chang Wang, Zun-Ting Zhang, Yong Chang
Turkish Journal of Chemistry
Pilloin was synthesized by methylation of luteolin and its structure was characterized by element analysis, ^1H-NMR, IR, and single-crystal X-ray diffraction analysis. It crystallizes in the monoclinic crystal system, space group P2_1/n, with a = 7.336(3) Å, b = 14.257(5) Å, c = 13.298(5) Å, \beta = 93.516(5)°. The flavone molecules of pilloin are linked into puckering sheets via R_3^3(14) and R_2^2(9) graph-set ring motifs defined by the C-H...O and O-H...O hydrogen bonds. \pi -\pi stacking interactions lead to the flavone skeletons of columns that are held together through centrosymmetric R_2^2(8) motifs. Hydrogen bonding and aromatic \pi -\pi stacking interactions …
A New Approach To The Calculation Of N-15 Chemical Shifts Of Cyclic Compounds, Emad A. S. Al-Hyali
A New Approach To The Calculation Of N-15 Chemical Shifts Of Cyclic Compounds, Emad A. S. Al-Hyali
Turkish Journal of Chemistry
Two sets of additive parameters used previously for the calculation of C-13 chemical shifts of mono and poly six-membered cycloalkanes were applied for the prediction of N-15 chemical shifts of some methyl piperidine derivatives. These sets are based on 2 principles: the p-character (substituents electronic effect) of the atom under consideration and the steric effect that reflects the spatial arrangement of the molecule. An additional parameter, namely the ring angle of the studied atom, was added to the other parameters to define the structural distortion that is due to large steric interactions. The p-character in set (1) is represented by …
Hydrogels Of Versatile Size And Architecture For Effective Environmental Applications, Nurettin Sahiner
Hydrogels Of Versatile Size And Architecture For Effective Environmental Applications, Nurettin Sahiner
Turkish Journal of Chemistry
Cationic hydrogels from a positively charged monomer, (3-Acrylamidopropyl)-trimethylammonium chloride (APTMACl), were synthesized as bulk, and micro- and nano-sizes. These hydrogels were utilized to remove contaminants such as food dyes and an environmentally toxic metal, arsenic. The micro- and nanohydrogels were dispersed in another hydrogel network to design a semi-interpenetrating network (semi-IPN) which was shown to visualize the particles that can be used for absorption purposes. The micron-sized cationic hydrogel particles were very effective in the removal of arsenic from an aqueous environment- 96% of the arsenic was removed in less than 10 min from a 55-ppm aqueous stock solution. Cationic …
Synthesis Of New Bengazole Analogues And Their Antimicrobial Activity, Jurgen Krauss, Sandra Kalkbrenner, Angela Schuster, Anne Obainoke, Franz Bracher
Synthesis Of New Bengazole Analogues And Their Antimicrobial Activity, Jurgen Krauss, Sandra Kalkbrenner, Angela Schuster, Anne Obainoke, Franz Bracher
Turkish Journal of Chemistry
Bengazole A and bengazole B are 2 representatives out of a large family of marine metabolites isolated from a Jaspis sponge and display potent anti-fungal and anthelmintic activity as well as modest cytotoxic activity. This paper reports a short and efficient synthesis and microbiological evaluation of some new bengazole analogues.
New Polyamides Derived From 2,5-Bis[(4-Carboxyanilino) Carbonyl] Pyridine And Hydantoin Derivatives: Synthesis And Characterization, Khalil Faghihi, Zohreh Mozaffari
New Polyamides Derived From 2,5-Bis[(4-Carboxyanilino) Carbonyl] Pyridine And Hydantoin Derivatives: Synthesis And Characterization, Khalil Faghihi, Zohreh Mozaffari
Turkish Journal of Chemistry
We synthesized 2,5-bis[(4-carboxyanilino) carbonyl] pyridine (4) as a new monomer containing pyridyl moiety by using a 2-step reaction. At first 2,5-pyridine dicarboxylic acid (1) was converted to 2,5-pyridine dicarbonyl dichloride (2). Then, diacid 4 was prepared by a condensation reaction of diacid chloride (2) with p-aminobenzoic acid (3). Then, 6 new polyamides (6a-f) were synthesized through the polycondensation reaction of 2,5-bis[(4-carboxyanilino) carbonyl] pyridine (4) with 6 different derivatives of hydantoins (5a-f) in a medium consisting of N-methyl-2-pyrrolidone, triphenyl phosphite, calcium chloride, and pyridine. The polycondensation reaction produced a series of novel polyamides containing pyridyl moiety in the main chain in …
Biotransformation Of Dydrogesterone By Cell Suspension Cultures Of Azadirachta Indica, . Azizuddin, - Saifullah, Saifullah Khan, Muhammad Iqbal Choudhary, - Atta-Ur-Rahman
Biotransformation Of Dydrogesterone By Cell Suspension Cultures Of Azadirachta Indica, . Azizuddin, - Saifullah, Saifullah Khan, Muhammad Iqbal Choudhary, - Atta-Ur-Rahman
Turkish Journal of Chemistry
Biotransformation of dydrogesterone (1) by using cell suspension cultures of Azadirachta indica yielded a metabolite 20R-hydroxy-9\beta ,10\alpha-pregna-4,6-diene-3-one (2). The structure of this compound was deduced on the basis of various spectroscopic techniques.
Synthesis And Antimicrobial Activities Of 1,2,4-Oxadiazin-5-One, 6-One And 5-Thiones, Nevi̇n Arikan, Doğan Sümengen, Başaran Dülger
Synthesis And Antimicrobial Activities Of 1,2,4-Oxadiazin-5-One, 6-One And 5-Thiones, Nevi̇n Arikan, Doğan Sümengen, Başaran Dülger
Turkish Journal of Chemistry
N-Substituted pyridine carboxamide oximes (2) were obtained from the reactions of pyridine hydroxamic acid chloride hydrochlorides (1) with primary amines. The reactions of carboxamide oximes with chloroacetyl chloride in the presence of triethylamine gave the corresponding 3,4-disubstituted-1,2,4-oxadiazin-5-ones (3), which on treatment with P_2S_5 gave in moderate yielded the corresponding 3,4-disubstituted-1,2,4-oxadiazin-5-thiones (4). The reaction of pyridine carboxamide oximes with \alpha-aminoacid ester led to the formation of 3,5-disubstituted-1,2,4-oxadiazin-6-ones (5) in moderate yields. The structures of the prepared compound were evaluated by spectroscopy. Some of the representatives of 3,4-disubstituted-1,2,4- oxadiazin-5-ones, thiones, and 3,5-disubstituted-1,2,4-oxadiazin-6-ones were screened for antibacterial activity using disc diffusion. It was …
Partial Regeneration Of Ni-Based Catalysts For Hydrogen Production Via Methane Cracking, Reyyan Koç, Erdoğan Alper, Eric Croiset, Ali Elkamel
Partial Regeneration Of Ni-Based Catalysts For Hydrogen Production Via Methane Cracking, Reyyan Koç, Erdoğan Alper, Eric Croiset, Ali Elkamel
Turkish Journal of Chemistry
Methane cracking has the potential to produce high purity, carbon monoxide-free hydrogen suitable for application in PEM fuel cells. The 2 products of the reaction are molecular hydrogen and solid carbon. The carbon appears in the form of carbon filaments whose growth is hindered by carbon encapsulation leading to total deactivation of the catalyst. Several attempts have been made to regenerate the catalyst, mainly by gasifying the carbon filament in air or steam. Our work on 5-wt% Ni/\gamma-Al_2O_3 indicated that after complete gasification of the carbon the catalyst lost nearly all its activity toward methane cracking. However, if the gasification …
Zinc Perchlorate Hexahydrate Catalyzed Mono- And Bis-Transesterification Of Malonic Esters, Servet Tural
Zinc Perchlorate Hexahydrate Catalyzed Mono- And Bis-Transesterification Of Malonic Esters, Servet Tural
Turkish Journal of Chemistry
Commercially available zinc perchlorate hexahydrate [Zn(ClO_4)_2.6H_2O] was found to be a highly effective catalyst for the transesterification of malonic esters with alcohols. The treatment of methyl-, ethyl-, or \alpha-substituted malonic esters with primary or secondary alcohols in the presence of a catalytic amount of zinc perchlorate results in good to high yields of the corresponding esters (68%-99%). Mono-transesterification products are also obtained in moderate to good yields (22%-42%). The reaction was also carried out with 2-mono- and di-substituted malonic esters, and in the case of 2-mono- and di-substituted malonic esters, the reaction time is, in some cases, shorter, in which …
Synthesis And Properties Of New Polyamides Based On 4-Phenylenediacrylic Acid And Hydantoin Derivatives In The Main Chain, Khalil Faghihi
Synthesis And Properties Of New Polyamides Based On 4-Phenylenediacrylic Acid And Hydantoin Derivatives In The Main Chain, Khalil Faghihi
Turkish Journal of Chemistry
Six new polyamides (5a-f) containing p-phenylenediacrylic and hydantoin moieties in the main chain were prepared by direct polycondensation reaction of 4-phenylenediacrylic acid (3) with 6 different hydantoin derivatives (4a-f) using thionyl chloride and pyridine as condensing agents and N-methyl-2-pyrolidone as solvent. These new polymers (5a-f) were obtained in high yield and inherent viscosity between 0.35-0.55 dL/g. The resulting polyamides were characterized by elemental analysis, viscosity measurements, thermal gravimetric analysis (TGA and DTG), solubility test, and FT-IR and UV-vis spectroscopy. 4-Phenylenediacrylic acid (3) was prepared by the reaction of terephthal aldehyde (1) with malonic acid (2) in the presence of pyridine.
Synthesis, Spectroscopic And Biological Investigation Of Cyclic Octapeptide: Cherimolacyclopeptide G, Rajiv Dahiya
Synthesis, Spectroscopic And Biological Investigation Of Cyclic Octapeptide: Cherimolacyclopeptide G, Rajiv Dahiya
Turkish Journal of Chemistry
A natural cyclic octapeptide cherimolacyclopeptide G (8) was synthesized by coupling of tetrapeptide units Boc-Gly-Ala-Val-Pro-OMe (5) and Boc-Ile-Tyr-Ala-Pro-OMe (6) after proper deprotection at carboxyl and amino terminals followed by cyclization of the linear peptide segment. The structure was elucidated by IR, ^1H-NMR, ^{13}C-NMR, FAB MS spectral data, and elemental analyses. The newly synthesized cyclopeptide was also evaluated for its antimicrobial, anthelmintic, and cytotoxic activities and found to exhibit potent anthelmintic and cytotoxic activity against earthworms, Megascoplex konkanensis, Pontoscotex corethruses, and Eudrilus species, and Dalton's lymphoma ascites (DLA) and Ehrlich's ascites carcinoma (EAC) cell lines. In addition, compound 8 possessed moderate …
Orthogonal Signal Correction -- Partial Least Squares Method For Simultaneous Spectrophotometric Determination Of Nickel, Cobalt, And Zinc, Ali Niazi, Amir Azizi
Orthogonal Signal Correction -- Partial Least Squares Method For Simultaneous Spectrophotometric Determination Of Nickel, Cobalt, And Zinc, Ali Niazi, Amir Azizi
Turkish Journal of Chemistry
The simultaneous determination of nickel, cobalt, and zinc mixtures by spectrophotometric method is a difficult problem in analytical chemistry, due to spectral interferences. By multivariate calibration methods, such as partial least squares (PLS) regression, it is possible to obtain a model adjusted to the concentration values of the mixtures used in the calibration range. Orthogonal signal correction (OSC) is a preprocessing technique used for removing the information unrelated to the target variables based on constrained principal component analysis. OSC is a suitable preprocessing method for partial least squares calibration of mixtures without loss of prediction capacity using spectrophotometric method. In …