Method of Designing a Corrugated Optical Waveguide Filter

The method of designing a corrugated optical waveguide filter is proposed to yield an arbitrary spectral profile of the reflection coefficient. It gives the functional dependence of the corrugation depth on distance along the wave propagation direction. The basis of the theory of the method is a combination of the effective index approach and the Fourier transformation technique. It represents the spectral profile of the reflection coefficient approximately to Fourier transformation of the spatial profile of the effective refractive index. Examples are presented to illustrate how to apply the technique.     

Scheduling in a multi-class series of queues with deterministic service times

We consider a problem of scheduling in a multi-class network of single-server queues in series, in which service times at the nodes are constant and equal. Such a model has potential application to automated manufacturing systems or packet-switched communication networks, where a message is divided into packets (or cells) of fixed lengths. The network is a series-type assembly or transfer line, with the exception that there is an additional class of jobs that requires processing only at the first node (class 0). There is a holding cost per unit time that is proportional to the total number of customers in the system. The objective is to minimize the (expected) total discounted holding cost over a finite or an infinite horizon. We show that an optimal policy gives priority to class-0 jobs at node 1 when at least one of a set ofm–1 inequalities on partial sums of the components of the state vector is satisfied. We solve the problem by two methods. The first involves formulating the problem as a (discrete-time) Markov decision process and using induction on the horizon length. The second is a sample-path approach using an interchange argument to establish optimality.The research of this author was supported by the National Science Foundation under Grant No. DDM-8719825. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the authors and do not necessarily reflect the views of the National Science Foundation.     

Synthesis, Characterization, and Antimicrobial Activity of Poly(acrylonitrile-co-methyl methacrylate) with Silver Nanoparticles

Nanotechnology is expected to open some new aspects to fight and prevent diseases using atomic-scale tailoring of materials. The main aim of this study is to biosynthesize silver nanoparticles (AgNPs) using Trichoderma viride (HQ438699); the metabolite of this fungus will help either in reduction of the silver nitrate-adding active materials which will be loaded on the surface of the produced AgNPs. Poly(acrylonitrile-co-methyl methacrylate) copolymer (poly (AN-co-MMA)) was grafted with the prepared AgNPs. The poly(AN-co-MMA)/AgNPs were examined against ten different pathogenic bacterial strains, and the result was compared with another four different generic antibiotics. The produced poly(AN-co-MMA)/AgNPs showed high antibacterial activity compared with the four standard antibiotics. Moreover, the grafting of these AgNPs into the copolymer has potential application in the biomedical field.     

Studies on Organophosphorus Compounds: The Synthesis of [1,3,2]-Diazaphospholes and [1,3,2]-Oxaazaphospholes

A number of spiro[cyclopentane (cyclohexane, and cycloheptane)-1,4′-perhydro-[1,3,2]diazaphosphole] derivatives (3a–c, 5a–c, 11a–c, and 12a–c) and spiro-[cyclopentane (cyclohexane, and cycloheptane)-1,4′-perhydro[1,3,2]oxaazaphos-phole] derivatives (7a–c) were prepared via an interaction of 2,4-bis-(4-methoxy-phenyl)-1,3,2,4-dithiaphosphetane-2,4-disulphide (1) with substances containing two functional groups.     

The Synthesis of Triazolothiadiazines and Thiadiazoles From 1,2-Bis-(4-amino-5-mercapto-1,2,4-triazol-3-yl)- Ethanol and Ethane

The reaction of DL-malic and succinic acids with thiocarbohydrazide afforded 1,2-bis[4-amino-5-mercapto-1,2,4-triazol-3-yl]-ethane derivatives 3a and 3b. The reaction of 3a,b with phenacyl bromide and benzoin afforded 1,2-bis-1,2,4-triazolo [3,4-b][1,3,4]thiadiazine derivatives 4 and 5. The carboethoxymethylation of 3a and 3b gave 6a and 6b, respectively, and their reactions with carbon disulfide and benzoylisothiocyanate gave the 1,2-bis-1,2,4-triazolo[3,4-b][1,3,4]thiadiazole 7 and 9, and with p-nitrobenzaldehyde gave a Schiff's base and dihydrothiadiazole 8. The structures were confirmed by using ¹ H and ¹³ C NMR spectra. Selected members of these compounds were screened for antimicrobial activity.     

Synthesis and cytotoxic activity of some new heterocycles incorporating cyclohepta[b]thiophene-3-carboxamide derivatives

A series of 2-amino-5,6,7,8-tetrahydro-4H-cyclohepta[b]thiophene-3-carboxamide-heterocyclic hybrids were synthesized, characterized and their cytotoxic potencies were assessed on four human cell lines. Cyanoacetamide derivative ( 5 ) was used as the key synthetic intermediate for the synthesis many derivatives in this study, derivatives 9 , 11 , 12 were formed by coupled compound 5 with different aryl/heteryl diazonium chlorides, Gewald reaction and Knoevenagel condensation were used for synthesis derivatives 13 , 14 , 16 by treated cyanoacetamide ( 5 ) with different reagents. In another route, compound 5 treated with phenyl isothiocyanate give thiocarbamoyl derivative ( 7 ) which used as intermediate underwent oxidative cyclization with different moieties to offer the corresponding thiazoles and thiophene 18 , 19 , 20 , 21 , respectively. in vitro cytotoxic activity of prepared compounds were tested against four human tumor cell lines. The result revealed that compound 11a displayed promising cytotoxic activity against HepG2, HCT-116, MCF-7, and PC3 cancer cell lines comparing to the positive control (Doxorubicin).     

Spectroscopic studies,Density Functional Theory calculations,and non-linear optical properties of binuclear Fe(III), Co(II), Ni(II), Cu(II), and Zn(II) complexes of OONN Schiff base ligand

The binuclear complexes of Fe(III), Co(II), Ni(II), Cu(II), and Zn(II) with 2-[3-(benzylideneamino)-2-(benzylidenehydrazono)-4-oxothiazolidin-5-yl] acetic acid ligand (HL) were prepared and their stoichiometry was determined by elemental analysis. The stereochemistry of the studied binuclear metal complexes was confirmed by analyzing their infrared spectra, ¹H NMR, and magnetic moment. Thermal decomposition studies of the binuclear complexes have been performed to demonstrate the status of water molecules present in these binuclear complexes and their general decomposition pattern. The equilibrium geometry of the ligand and its studied complexes were calculated using density function theory (DFT) calculations at the B3LYP/GENECP level of the theory. The results show that the ligand and its complexes are nonplanar structures as indicated from the values of the dihedral angles. Extent of distortion from regular geometry has been performed and discussed in terms of the values of the angles between the central metals and the coordinated sites. The E_HOMO and E_LUMO energies of the studied ligand and its complexes are used to calculate the global properties. The nonlinear optical parameters (NLO), anisotropy of the polarizibility (Δα), and the mean first-order hyperpolarizability (<β>) were calculated. The (<β>) values were compared with Urea as a reference molecule and the results of (<β>) values showed that the ligand and the studied complexes have good NLO behaviors.     

Synthesis,characterization and cytotoxic activity of ferrocenyl hydrazone complexes containing a furan moiety

A ferrocenyl ligand 1 was prepared from condensation of 5-methyl-2-furaldehyde with l,l′-diacetylferrocene dihydrazone. This ligand forms 1:1 complexes with cobalt(II), nickel(II), copper(II) and zinc(II) 2–5 in good yield. Characterization of the ligand and complexes was carried out using infrared, nuclear magnetic resonance, mass spectra, electronic absorption, magnetic susceptibility, molar conductivity, and elemental analysis. Cytotoxic activity of the prepared ligand and its complexes were tested against different human cancer cell lines. The results suggested that the synthesized compounds were more potent than the comparative standards drugs used in most cases, whereas they had less activity in the others.     

Syntheses,Crystal Structures and Ligand Field Properties of Iron(II) Complexes with PNP Ligands: Origin of Large Ligand Field by a Phosphorous Donor Atom

New iron(II) complexes were synthesized with two tridentate hybrid ligands having phosphorous and nitrogen donor sites, in order to quantitatively estimate the difference of the ligand-field strengths of phosphorous and nitrogen donor sites in cationic metal complexes. Iron(II) complexes with bis(dimethylphosphinoethyl)amine (PNP) and 2,6-bis(diphenylphosphinomethyl)pyridine (PpyP) ligands crystallized as un-symmetric facial-[Fe(PNP)₂](PF₆)₂·CH₃NO₂ and mer-[Fe(PpyP)₂](CF₃SO₃)₂, respectively, as expected from the steric congestion and from the tendency to avoid the mutual trans influence between two phosphorous donor sites. Both complexes are in the low-spin electronic state up to 400 K. The pseudo-D _4h coordination geometry of the PpyP complex made it possible to separate axial (2 × N) and equatorial (4 × P) contributions to the overall ligand-field by means of a spectrometric method: the difference in the ligand-field strengths by the equatorial Ph₂P-donor sites and by the axial 2,6-disubstituted pyridine donor sites is ca. 13,200 cm^?1. A significantly reduced inter-electronic repulsion parameter (425 cm^?1 for both PNP and PpyP complexes) from the value of the free ion (1,060 cm^?1) indicates covalent interaction between the Fe(II) and P atoms even in these cationic metal complexes. It is shown that the degree of covalency as well as the coordination bond strengths between various metal ions and phosphorous/nitrogen donor atoms is successfully explained by the relative energy levels of interacting atomic orbitals calculated on the basis of the Thomas–Fermi–Dirac potential.     

Synthesis and antibacterial evaluation of fused pyrazoles and Schiff bases

Abstract

For the discovery of new antibiotic drugs to face the problem of microbial resistance, a series of fused pyrazoles such as pyrazolopyrimidines 15a–f, pyrazoloquinazolines 18a, b and pyrazolotriazines 20a, b was synthesized via the reaction of 5-aminopyrazoles 8a, b with 3-(dimethylamino)-1-aryl-prop-2-en-1-ones 9a–d, 2-((dimethylamino)methylene)-5,5-dimethylcyclohexane-1,3-dione (16) and sodium nitrite (NaNO₂), respectively. Finally, Schiff bases 22a–g were obtained by the condensation of 8a, b with aromatic aldehydes 21a–d. The chemical structure of the new compounds was confirmed by spectroscopy. The structure of 15?b was confirmed by X-ray crystallography analysis. All compounds were screened for antibacterial properties toward multi-drug resistant bacteria (MDRB).