Energy transfer in zinc porphyrin-phthalocyanine heterotrimer and heterononamer studied by fluorescence resonance energy transfer (FRET)

Two or eight zinc triphenyl porphyrins were conjugated with Zn-phthalocyanine or H2-phthalocyanine to form ZnPc-(ZnTPP)2, ZnPc-(ZnTPP)8, H2Pc-(ZnTPP)2 and H2Pc-(ZnTPP)8. Energy transfers from the porphyrin moiety to phthalocyanine part were quantitatively studied with the modality of fluorescence resonance energy transfer (FRET). By measuring the fluorescence increment from the phthalocyanine moiety and the decrease from porphyrin part under selective excitation at the B band of the porphyrin part in those conjugated compounds and their equimolar mixture of compositions, energy transfer efficiencies were estimated to be 90% for H2Pc-(ZnTPP)8 and ZnPc-(ZnTPP)8, and 60%, 30% for ZnPc-(ZnTPP)2 and H2Pc-(ZnTPP)2, respectively.     

Channel architecture via self assembly of oxamide oximes complexes

The nickel(II) and palladium(II) complexes of oxamide oximes substituted with alkyl chains of different length (C4-C8) were synthesized from the reaction of dichloroglyoxime with the corresponding amine derivatives. All compounds have been characterized by X-ray diffraction on single crystals and were found to be centrosymmetric at the metal center which is bound by the four oximic nitrogen atoms of two ligands in a square planar environment. Crystal structure analyses of Ni(II) and Pd(II) complexes showed that all of the Pd(II) complexes but only the hexyl-substituted oxamide oxime Ni(II) complex form infinite tubular channels. Their conformational analyses were carried out in order to understand the role of the chain length and of the metal center in the formation of the tubular channels and it was found that the formation of infinite tubular channels in crystals of Ni(II) and Pd(II) alkyl-substituted oxamide oxime complexes is related to the orientation of the alkyl chains relative to the central core.     

On the Riesz difference sequence space

In the present paper, we define the difference sequence space r ^q (p, Δ), which is defined as follows:

Quasi-power increasing sequence for generalized absolute summability

In this paper, we prove a theorem given in [E. Sava?, On almost increasing sequences for generalized absolute summability, Math. Inequal. Appl., Preprint] on summability factors under weaker conditions by using a quasi-β$\beta$-power increasing sequence instead of an almost increasing sequence.     

On generalized absolute summability factors

In this paper, a general theorem on _|A,δ|k${|A,\delta |}_k$-summability factors which generalize a theorem of Sava? [E. Sava?, On a recent result on absolute summability factors, Appl. Math. Lett. 18 (2005) 1273–1280] on _|A|k${\left|A\right|}_k$-summability factors has been proved.     

Physico-chemical and thermodynamic aspects of fibroblastic attachment on RGDS-modified chitosan membranes

In the present study, the cell attachment/spreading behaviour of L929 mouse fibroblasts on chitosan membranes was evaluated by using physico-chemical properties. For this purpose chitosan membranes were prepared and then photochemically modified with the cell adhesive peptide RGDS (Arg-Gly-Asp-Ser). The physico-chemical properties of unmodified (CHI) and RGDS-modified chitosan (CHI-RGDS) membranes were evaluated by calculating surface free energy (γ_sv) and interfacial free energy (γ_sw) values using captive bubble contact angle measurements and harmonic mean equation. The cell attachment experiments were performed both in 10% FBS containing and serum-free media with CHI and CHI-RGDS membranes. Eventually, it was not possible to predict a direct relationship between the change in physico-chemical properties and L929 cell attachment behaviour. The experimental results obtained from cell attachment agree with the theoretical prediction for the free energy of adhesion except for the cell attachment on CHI membrane in serum-free medium. Although a negative interfacial free energy of adhesion was calculated for CHI membrane in serum-free medium (ΔF_adh = −2.19 ergs/cm²), the cell attachment was poor (70%) compared to CHI-RGDS (90%) and none of the cells were spread on CHI surface to gain a fibroblastic morphology. Negative energy of adhesion was calculated for CHI and CHI-RGDS in 10% FBS medium, in which 100% of cells were attached on the membranes correlating with the thermodynamic approach. It can be suggested that, adsorption of serum proteins strongly affected the cell attachment meanwhile the presence of biosignal RGDS molecules triggered the cell spreading in serum medium.     

Biosorption of Ni(II) from aqueous solutions by living and non-living ureolytic mixed culture

The present study explores the ability and the comparison of living and non-living ureolytic mixed culture (UMC) to remove Ni(II) from aqueous solution. Time dependency experiments for the Ni(II) uptake showed that adsorption equilibrium was reached almost 110 and 60 min after addition Ni(II) of 100mg/L. The kinetic data were analyzed in term of pseudo-first-order and pseudo-second-order expressions. Ni(II) sorption of living UMC was appropriate with pseudo-first-order kinetic (k(1)=2.15 h(-1), R(2)=0.93) while non-living UMC sorbed Ni(II) with respect to second-order kinetics (k(2)=1.64 g/mgh, R(2)=0.98). Also, comparison between the biosorption capacity of untreated living and non-living biomass was conducted for removal of Ni(II). The biosorption process was investigated in equilibrium batch tests for Langmuir, Freundlich and Temkin isotherm models. The data pertaining to the sorption dependence upon Ni(II) ion concentration ranged from 5 to 320 mg/L could be fitted to a Freundlich isotherm model. The capacity constants K of Freundlich model for living and non-living UMC were 1.55 and 0.38 mg/g, respectively; the affinity constants 1/n were 0.47 and 0.75, respectively. Based on the results, the UMC appear to be a potential biosorbent for removal of Ni(II) from wastewater.     

Synthesis,Characterization and Electrochemistry of New Soluble Porphyrazine Complexes Bearing Octakis 3‐Methylbutylthio Substituents

Porphyrazines, MPz (M = Mg, H, Ni, Zn and Co) with octakis 3‐methylbutylthio substituents have been synthesized starting with the corresponding unsaturated dicarbonitrile derivative. These new compounds have been characterized by UV‐Vis, FT‐IR, ¹H NMR, MS and elemental analysis methods. Voltammetric properties of the complexes were also investigated by CV, DPV and CPC techniques. Electrochemical studies show that three reversible one electron reductions and one reversible one electron oxidation processes (two for Co^IIPz) are observed for all of the complexes. The E_1/2 values are similar for the H₂Pz, Ni^IIPz and Zn^IIPz derivatives with negative shift due to the different effective nuclear charges of the central metal ion. Peak to peak separations and separation between the first reduction and first oxidation couples related with the HOMO‐LUMO gap of the complexes are in harmony with the common porphyrazine complexes.     

A simple one‐pot synthesis of 1,2,3,4‐tetrahydro‐2‐thioxopyrimidine derivatives

5‐Benzoyl‐4‐(substituted phenyl)‐6‐phenyl‐1,2,3,4‐tetrahydro‐2‐thioxopyrimidines ( 4a‐d ) were synthesized using the Biginelli three component cyclocondensation reaction of an appropriate β‐diketone, arylaldehyde, and thiourea in acetic acid under reflux condition in approximately 52‐65% yields. The acetylation of compounds 4a‐d gave 3‐acetyl thioxopyrimidine derivatives 5a‐d . Also, pyrimidothiazine compounds 6a‐d were prepared by a simple one‐pot condensation reaction of starting pyrimidine derivatives 4a‐d and 3‐bromopropionic acid. The structures of compounds were characterized on the basis of elemental analyses, IR, ¹H and ¹³C‐NMR spectra.     

Hydroxyl radical detection with a salicylate probe using modified CUPRAC spectrophotometry and HPLC

Reactive oxygen species (ROS) may attack biological macromolecules giving rise to oxidative stress-originated diseases, so it is important to establish efficient methods to screen hydroxyl radical scavengers for antioxidant therapy. Since *OH is very short-lived, secondary products resulting from *OH attack to various probes are measured. As a low-cost measurement technique, we used a salicylate probe for detecting hydroxyl radicals generated from an equivalent mixture of Fe(II)+EDTA with hydrogen peroxide. The produced hydroxyl radicals attacked both the probe and the water-soluble antioxidants in 37 degrees C-incubated solutions for 2 h. The CUPRAC (cupric ion reducing antioxidant capacity) assay absorbance of the ethylacetate extract due to the reduction of Cu(II)-neocuproine reagent by the hydroxylated probe decreased in the presence of *OH scavengers, the difference being proportional to the scavenging ability of the tested compound. Attack by *OH radicals upon salicylate produced 2,3-dihydroxybenzoate, 2,4-dihydroxybenzoate, and 2,5-dihydroxybenzoate as major products. HPLC separation combined with CUPRAC spectrophotometry was used to identify and quantify hydroxylated salicylate derivatives in the presence of synthetic water-soluble antioxidants and green tea infusion. The developed spectrophotometric method for *OH detection was validated with HPLC, i.e., the concentrations of dihydroxybenzoates produced by radical attack from the probe were determined by HPLC, and the sum of (concentrationxabsorptivity) products of these components approximately agreed with the experimentally found CUPRAC absorbances, confirming the validity of Beer's law for the selected system. Statistical comparison of the results found with the proposed methodology and HPLC was made with two-way ANOVA (analysis of variance) test. Under optimal conditions, about 53% of the probe (salicylate) was converted into dihydroxybenzoate isomers in the absence of *OH scavengers, and these isomers were more specific markers of hydroxyl radicals than the non-specific malondialdehyde end-product of the TBARS test. Thus, the more costly and less speedy HPLC method could advantageously be substituted with the proposed spectrophotometric assay of *OH detection, which was also of much higher yield than the TBARS colorimetric assay.