Frictional heat is generated when the clutch starts to engag. As a result of this operation the surface temperature is increased rapidly due to the difference in speed between the driving and driven parts. The influence of the thickness of frictional facing on the distribution of the contact pressure of the multi-disc clutches has been investigated using a numerical approach (the finite element method). The analysis of contact problem has been carried out for a multiple disc dry clutch (piston, clutch discs, separators and pressure plate). The results present the distribution of the contact pressure on all tShe surfaces of friction discs that existed in the friction clutch system. Axisymmetric finite element models have been developed to accomplish the contact analysis in this work. Thickness of the frictional facing of a clutch disc is a significant parameter that affects the elastic and thermal behaviors of a dry friction clutch. The results proved that the magnitudes of the contact pressure are increased dramatically when the thickness of the friction facing decreases.
New 1,3-oxazol-5(4H)-one(3) was synthesized by cyclization of[(4-Methyl phenyl-carbonyl)amino]acetic acid (2). The starting materials were readily obtained by acylation of 2-amino acetic acid (Glycine) with 4-methyl phenyl chloride .Imidazole(4) was synthesized by reaction of compound (3) with hydrazine hydrate (99%). Compound (4) was isolated and characterized by 1HNMR , FTIR , uv-vis spectroscopy and elemental analysis (C.H.N). Compound (4) has been used as a ligand (L) to prepare a number of metal complexes with Cr(III), Mn(II), Co(II), Ni(II) , Cu(II) and Zn(II).
The prepared complexes were isolated and characterized by FTIR and Uv-vis spectroscopy elemental analysis (C.H.N), flame atomic absorption technique, as well as magnetic
Sildenafil, tadalafil, and vardenafil are phosphodiesterase type 5 enzyme (PDE-5) inhibitors used for the treatment of male erectile dysfunction. This present study aims to investigate 55 herbal products indicated for men’s sexual health from the Malaysian market for adulteration of PDE-5 inhibitors and analogues. The screening and identification of 20 PDE-5 inhibitors and analogues in herbal products of various forms (powder, capsules, tablets, and pastels) were conducted using gas chromatography–electron impact-mass spectrometer (GC-EI-MS). The analysis has shown that 19 herbal products were adulterated with PDE-5 inhibitors and analogues. Unique ion fragmentations and the presence of molecular
... Show MoreThe formation of Co(II), Ni(II), Cu(II), Zn(II), and Cd(II)-complexes (C1-C5) respectively was studied with new Schiff base ligand [benzyl(2-hydroxy-1-naphthalidene) hydrazine carbodithioate derived from reaction of 2-hydroxy-1-naphthaldehyde and benzyl hydrazine carbodithioate. The suggested structures of the ligand and its complexes have been determined by using C.H.N.S analyzer, thermal analysis, FT-IR, U.V-Visible, 1HNMR, 13CNMR , conductivity measurement , magnetic susceptibility and atomic absorption. According to these studies, the ligand coordinates as a tridentate with metal ions through nitrogen atom of azomethane , oxygen atom of hydroxyl, and sulfur atom of thione
... Show MoreSynthesis of new heterocyclic compounds containing four five-membered rings together was the main goal of this work. The new derivatives of [tetrakis (1,2,4-triazole /1,3,4-thiadiazole /1,3,4-oxadiazole][bis-(benzene-1,3,5-triyl)] dioxymethylene A7-A18 were synthesized by the reaction of [bis-(dimethyl 5-yl-isophthalate)] dioxymethylene compound A1 which was previously prepared from the reaction of 1,2-dibromomethan and dimethyl 5-hydroxyisophthalate, then treated with hydrazine hydrate to yield the corresponding acid hydrazide A2. In the next step, compound A2 was refluxed with 4-substituted isothiocyanate to give substituted thiosemicarbazides A3-A6. The treatment of the latter compounds in basic medium of 2M o
... Show MoreThis research of the thesis includes the preparation and identification of two new tetra dentate Schiff's base ligand . (H4L1 ) and then binuclear complexes with a group of transition metal ions in addition to cadmium with the general formula. [M2(L1)Cl2(H2O)2] M+2=[Mn,Co,Ni,Cu and Cd] The prepared complexes and ligands were identified by in pared(FT-IR) spectroscopy ,Ultra violet-visible(UV-visible) spectroscopy and H-NMR spectroscopy of the prepared ligand, also microanalysis (C.H.N) of some of the prepared compounds has been carried out and the melting points, the molar conductivity and magnetic susceptibility
Background: Occult Hepatitis B virus infection (OBI) among blood donors is an important medical concern.
Objectives: This study was done to detect the presence of occult hepatitis B virus infections among blood donors with negative hepatitis B surface antigen and positive total anti-hepatitis B core antibodies in Hawler Major Blood Bank in Hawler city/Kurdistan Region of Iraq.
Methods: A total number of 12,185 blood donors in Hawler Major Blood Bank were screened for HBsAg and total anti-HBcAb using ELISA technique, and then positive results were retested by confirmatory technique by Chemiluminescence assay. All HBsAg-/HBcAb+ were selected as the study group; HBV DNA was tested among HBsAg-/HBcAb+ by conventional PCR and Real time-
. New Schiff base ligand 2-((4-amino-5-(3, 4, 5-trimethoxybenzyl) pyrimidin2-ylimino) (phenyl)methyl)benzoic acid] = [HL] was synthesized using microwave irradiation trimethoprim and 2-benzoyl benzoic acid. Mixed ligand complexes of Mn((ІІ), Co(ІІ), Ni(ІІ), Cu(ІІ), Zn(ІІ) and Cd(ІІ) are reacted in ethanol with Schiff base ligand [HL] and 8-hydroxyquinoline [HQ] then reacted with metal salts in ethanol as a solvent in (1:1:1) ratio. The ligand [HL] is characterized by FTIR, UV-Vis, melting point, elemental microanalysis (C.H.N), 1H-NMR, 13C-NMR, and mass spectra. The mixed ligand complexes are characterized by infrared spectra, electronic spectra, (C.H.N), melting point, atomic absorption, molar conductance and magnetic m
... Show MoreBackground: In young adults, multiple sclerosis is a prevalent chronic inflammatory demyelinating condition. It is characterized by white matter affection, but many individuals also have significant gray matter involvement. A double-inversion recovery pulse (DIR) pattern was recently proposed to improve the visibility of multiple sclerosis lesions. Objective: To find out how well a DIR sequence, FLAIR, and T2-weighted pulse sequences can find MS lesions in the supratentorial and infratentorial regions. Methods: A total of 37 patients with established diagnoses of multiple sclerosis were included in this cross-sectional study. Brain MRI was done using double inversion recovery, T2, and FLAIR sequences. The number of lesions was count
... Show MoreThere are many tools and S/W systems to generate finite state automata, FSA, due to its importance in modeling and simulation and its wide variety of applications. However, no appropriate tool that can generate finite state automata, FSA, for DNA motif template due to the huge size of the motif template. In addition to the optional paths in the motif structure which are represented by the gap. These reasons lead to the unavailability of the specifications of the automata to be generated. This absence of specifications makes the generating process very difficult. This paper presents a novel algorithm to construct FSAs for DNA motif templates. This research is the first research presents the problem of generating FSAs for DNA motif temp
... Show More