This paper studies the effect of contact areas on the transient response of mechanical structures. Precisely, it investigates replacing the ordinary beam of a structure by two beams of half the thickness, which are joined by bolts. The response of these beams is controlled by adjusting the tightening of the connecting bolts and hence changing the magnitude of the induced frictional force between the two beams which affect the beams damping capacity. A cantilever of two beams joined together by bolts has been investigated numerically and experimentally. The numerical analysis was performed using ANSYS-Workbench version 17.2. A good agreement between the numerical and experimental results has been obtained. In general, results showed that the two beams vibrate independently when the bolts were loosed and the structure stiffness is about 20 N/m and the damping ratio is about 0.008. With increasing the bolts tightening, the stiffness and the damping ratio of the structure were also increased till they reach their maximum values when the tightening force equals to 8330 N, where the structure now has stiffness equals to 88 N/m and the damping ratio is about 0.062. Beyond this force value, increasing the bolts tightening has no effect on stiffness of the structure while the damping ratio is decreased until it returned to 0.008 when the bolts tightening becomes immense and the beams behave as one beam of double thickness.
This research includes the application of non-parametric methods in estimating the conditional survival function represented in a method (Turnbull) and (Generalization Turnbull's) using data for Interval censored of breast cancer and two types of treatment, Chemotherapy and radiation therapy and age is continuous variable, The algorithm of estimators was applied through using (MATLAB) and then the use average Mean Square Error (MSE) as amusement to the estimates and the results showed (generalization of Turnbull's) In estimating the conditional survival function and for both treatments ,The estimated survival of the patients does not show very large differences
... Show MoreObjective(s): Biocompatibility, non-toxicity, minimal allergenicity, and biodegradability are all characteristics of chitosan. Other biological properties of chitosan have been reported, including antitumor, antimicrobial and antioxidant activities. This research aim is the synthesis of drug compounds by preparation and characterization of polymer chitosan Schiff base and chitosan Schiff base / Poly vinyl alcohol / poly vinyl pyrrolidone Nanocomposite and study applications (anticancer cell line, antimicrobial agents). Methods: Chitosan Schiff base was prepared from the reaction of chitosan with carbonyl group of 4-nitro benzaldehyde. Polymer blend have been prepared by solution casting method. Chitosan Schiff base mixing with PVA and PVP
... Show MoreABSTRACT Background: One of the methods used in the treatment of maxillofacial fracture is intermaxillary fixation(IMF), the most common type is the Erich arch bar with interdental wiring. This study was conducted to investigate the impact of intermaxillary fixation on gingival health condition among a group of patients with facial fracture in relation to salivary physical properties. Materials and methods: Thirty patients with an age range of (17-37) years old with facial fractures and indicated for IMF. Plaque index and gingival index (Loe, 1967) were used to assess both of them before application and after removal of IMF. Unstimulated saliva sample collection was carried out under standardized conditions according to Navazesh and Kum
... Show MoreGrowth hormone deficiency is a condition that occurs when a limited volume of growth hormone is released by the pituitary gland since growth hormone deficiency causes growth delays, short stature, and overall physical development delays. symptoms differ based on the age at which they occur .Aim of this study Estimating the level of growth hormone serotonin ,IGF-1 and Chromogranin A before and after with treatment recombinant growth hormone and It is the first study in Iraq that sheds light on the relationship between Chromogranin and other variables ( somatostatin, IGF-1,GH) ,also the prediction of Chromogranin A as a newly biochemical marker in children with growth hormone deficiency. In this study, 30 samples were collected from children
... Show MoreLow temperature and high relative humidity in the spring season led to decrease of field emergence ratio and growth in maize. Planting dates and seeds stimulation can be appropriate fix. Field experiment was conducted in the two spring seasons of 2022 and 2023. Randomize complete block design with split-plot arrangement and four replications was used. Planting date treatments (February 15th, March 1st and 15th and April 1st, 15th) were placed in main plots. Seeds stimulation treatments (potassium nitrate 6 mg L-1 + licorice extract 6 g L-1 as well as treatment of soaking with distilled water only) were placed in subplots. Seeds stimulation (potassium nitrate+licorice extract) or planting date of February 15th were superior at traits of fiel
... Show MoreBackground: Sex variations in coronary artery disease (CAD) are well documented. However, sex differences in coronary artery calcium (CAC) and its role in the detection of coronary artery stenosis remain controversial. Objective: To assess the impact of sex variation on coronary artery calcification and its efficacy in predicting coronary artery stenosis. Methods: This is a cross-sectional observational study including 230 consecutive patients with suspected CAD (120 men and 110 women) referred for coronary computed tomography angiography (CCTA). The study analyzed sex-based differences in the sensitivity and specificity of coronary artery calcification (CAC) for detecting moderate to severe stenosis across various coronary arteries
... Show MoreThis study estimated seven heavy metals (Fe, Cu, Zn, Pb, Ni, Cd, Cr) in water (dissolved and particulate phase), sediments and some aquatic organisms including two species from aquatic plants (Ceratophyllum demersum&Phragmites australis); one species of clam (Psedontopeses euphratics) and two species from fish (Oreochromis aureus& Leuciscus vorax)in four sites within Mashroo AL- Musayyib channel project/ branch of Euphrates river, Babylon , medial of Iraq . This aims to show the concentration of these elements, their fate and the mechanisms of their transmission through the food chain in this lotic aquatic system ; also in addition to examining some physicochemical properties of ri
... Show MorePhotodynamic Action (PDA) by using appropriate wavelength of irradiation conjugated with porphyrin derivatives is a powerful mechanism of tumor destruction. Hematoporphyrin derivative has been shown to selectively localize in neoplastic cells and then cause destruction of them by generation of singlet oxygen when activated by low power He-Ne laser. Light which used in this study has been emitting from this laser has a wavelength equal to 632.8 nm (red light). Doses of laser had been varied from 3.6 J/cm2 to 14.4 J/cm2 . The beam of laser adjusted with a modified tissue culture plate. Cell lines had exposed to Hematoporphyrin D (HpD) for 24 hours before Laser exposure, their concentrations were varied from 5 µg/ml to 80 µg/ml. Resu
... Show MoreBackground: Toxoplasmosis is a very common infection caused by the obligate intracellular protozoan parasite. This parasite is called Toxoplasma gondii widely distributed around the world . Toxoplasma gondii can be vertically transmitted to the fetus during pregnancy and may cause wide range of clinical manifestations in the offspring.
Objective: To determine seroprevalence Immunoglobulin G (IgG) and Immunoglobulin M (IgM ) to toxoplasma gondii among pregnant women and to identify the risk factors.
Type of the study: A cross-sectional study.
Methods: A total of 110 blood samples of pregnant women were collected from
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