Molar conductivity of ascorbic acid (AA) with some α–amino acids (glycine (Gly), methionine (Met), cysteine (Cys) and tryptophan (Trp)) in aqueous solution was measured at range temperatures from 298 K to 313 K. Λo. The limiting molar conductivity, KA, the association constant was calculated using the Shedlovsky method, and R, the association distance calculated by Stokes–Einstein equation. The thermodynamic parameters (The heat of association ΔHo, the change in Gibbs free energy ΔGo, the change of entropy ΔSo), and (ΔES), the activation energy were also calculated. All of the results obtained were discussed. The data showed the increasing in Λo, with the increasing of temperature. The positive values for (ΔSo) and (ΔES) showed a decrease in solvation of ion–pair and signifying the higher mobility of the ions. The negative value of ΔHo, refers that the association processes are exothermic. The negative values of ΔGo, are for ion association in aqueous solution and increase with the increase in temperature.
In this study, NaOH dissolution method was applied to dissolve cellulose fibers which extracted from date palm fronds (type Al-Zahdi) taken from Iraqi gardens. In this process, (NaOH)-solution is brought into contact with the cellulose fibers at low temperature. Experiments were conducted with different concentrations of NaOH (4%, 6%, 8% and12%) weight percent at two cooling bath temperatures (-15 oC) and (-20oC). Maximum cellulose dissolution was 23 wt% which obtained at 8 wt% concentration of NaOH and at cooling bath temperature of -20oC. In order to enhance the cellulose fibers dissolution, the sample was pretreated with Fenton's reagent which consists of
... Show MoreThis study conduct in Al-Muthanna governorate to assess five concentrations of
Background: Propolis has received great interest because of its wide range antimicrobial activity. Propolis also called (bee glue) due to its collection by (Apismellifera) honeybees from various plants resinous substance. The aim of this study was to determine the antibacterial effect of propolis extracts (aqueous and alcoholic) on anaerobic periodontal pathogen namely Aggregatibacteractinomycetemcomitans. Materials and Methods: Strains of Aggregatibacter actinomycetemcomitans wasisolated from pockets of systemically healthy patients aged between 35-55 years old suffering from chronic periodontitis with pocket depths of 5-6 mm, the bacteria cultured on special blood Agar plates solid media. Propolis was extracted by using water and alcohol.
... Show MoreMercury can have significant impact on petroleum and related industries, it is also known to poison catalysts used in refining processes.Wet ash methods was widely used in determination of mercury in crude oil but the elemental and organic mercury are volatile and losses are also expected .An investigation of the use of Aqueous solution to prevent loss of mercury during wet digestion resulted in consistently good recoveries from crude oil samples.In this research diluted aqueous solution of sodium polysulfide is used and the parameters studied are polysulfide aqueous solution concentration, time, and ratio of the aqueous solution to crude oil,and will take different forms of heavy crude oil from several fields and the previous measuremen
... Show MoreMetal complexes of Cu (II), Fe (III) and Mn (II) with Quinaldic acid (L1) and 1, 10-Phenathroline (L2) are synthesized and characterized by standaral physic- chemical procedures (element analysis, metal analysis, FTIR, Uv-Vis, magnetic moment and conductometeric measurements). On the base of these studies, mononuclear and six coordinated octahedral geometry and nonelectrolyte of these complexes have been proposed. The standard heat of formation (?Hºf) and binding energy (?Eb) for the free ligands and their complexes are calculated by using the PM3 method at 273K of Hyperchem.-8 program. The complexes are more stable than their ligands. Moreover, the electrostatic potential of free ligands are measured to investigate the reactive site of th
... Show MoreRheumatoid arthritis (RA) is a chronic inflammatory disease associated with decreased antioxidant state .This study aim to investigate the status of oxidant/antioxidant in a sample of Iraqi patients with RA and the role of peroxynitrite and its natural scavenger uric acid in them .This case-controlled study was conducted at Baghdad teaching hospital /Baghdad from December 2010-May 2011 . Twenty-five patients with mean age 39 years and 25 apparently healthy subject as controls with mean age 29 years were included in the study .Investigations include estimation of serum levels of nitric oxide (NO) ,peroxynitrite (PN) , malondialdehyde (MDA) , and uric acid (UA) .Serum PN levels were significantly elevated in RA patients a
... Show MoreABSTRACT : A new ligand [ 2- (3-acetylthioureido)-3-phenylpropanoic acid (APA) is synthesized by reaction of acetyl isothiocyanate with phenylalanine (1:1). It is characterized by micro elemental analysis (C.H.N.S.), FT-IR, (UV-Vis) and 1H and 13CNMR spectra. Some metals ions complexes of this ligand were prepared and characterized by FT-IR, UV-Visible spectra, conductivity measurements, magnetic susceptibility and atomic absorption. From results obtained, the following formula [M(APA)2] where M2+ = Mn, Co, Ni, Cu, Zn, Cd and Hg, the proposed molecular structure for these complexes as tetrahedral geometry, except copper complex is has square planer geometry.
The focus of this article, reviewed a generalized of contraction mapping and nonexpansive maps and recall some theorems about the existence and uniqueness of common fixed point and coincidence fixed-point for such maps under some conditions. Moreover, some schemes of different types as one-step schemes ,two-step schemes and three step schemes (Mann scheme algorithm, Ishukawa scheme algorithm, noor scheme algorithm, .scheme algorithm, scheme algorithm Modified scheme algorithm arahan scheme algorithm and others. The convergence of these schemes has been studied .On the other hands, We also reviewed the convergence, valence and stability theories of different types of near-plots in convex metric space.
Introduction: This study was performed to compare the effect of Fractional CO2 laser or Q switched Nd:YAG laser of surface treatment on the shear bond strength of zirconia-porcelain interface. Methods: Fractional CO2 laser at 30 W, 2 ms, time interval 1 ms, distance between spots 0.3 mm, and number of scans is (4) or Q switched Nd:YAG laser at 30 J/mm2 and 10 Hz were used to assess the shear bond strength of zirconia to porcelain. Pre-sintered zirconia specimens were divided into three groups (n = 10) according to the surface treatment technique used: (a) untreated (Control) group; (b) CO2 group; (c) Nd:YAG group. All samples were then sintered and veneered with porcelain according to the manufacturer’s instructions. Surface morph
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