Double-layer micro-perforated panels (MPPs) have been studied extensively as sound absorption systems to increase the absorption performance of single-layer MPPs. However, existing proposed models indicate that there is still room for improvement regarding the frequency bands of absorption for the double-layer MPP. This study presents a double-layer MPP formed with two single MPPs with inhomogeneous perforation backed by multiple cavities of varying depths. The theoretical formulation is developed using the electrical equivalent circuit method to calculate the absorption coefficient under a normal incident sound. The simulation results show that the proposed model can produce absorption coefficient with wider absorption bandwidth compared with the conventional double- and even triple-layer MPPs. The bandwidth can be increased to higher frequency by decreasing the cavity depth behind a sub-MPP with small hole diameter and a high perforation ratio, and to lower frequency by increasing the cavity depth behind a sub-MPP with large hole diameter and a small perforation ratio. The experimental data, measured by impedance tube, are in good agreement with the predicted results.
Four metal complexes mixed ligand of 2-aminophenol (2-AP) and tributylphosphine (PBu3) were produced in aqueous ethanol with (1:2:2) (M:2-AP:PBu3). The prepared complexes were identified by using flame atomic absorption, FT.IR and UV-Vis spectroscopic methods as well as magnetic susceptibility and conductivity measurements. In addition antibacterial activity of the two ligands and mixed ligand complexes oboist three species of bacteria were also examined. The ligands and their complexes show good bacterial activities. From the obtained data the octahedral geometry was suggested for all prepared complexes.
Background: Oral mucositis is regarded as one of the major complications of radiation therapy especially in patients with head and neck cancer. The aim of this study was to evaluate the efficacy of glutamine in preventing or minimizing the development of mucositis of the oral cavity. Subjects and methods: Forty-six participants were randomly selected amongst those who were planned to receive radiation therapy for head and neck region cancers. They were randomly divided into two groups of 23 subjects, one group received glutamine and the second group received a placebo. Results: Glutamine had a statistically significant effect in reducing the occurrence and/or severity of oral mucositis in the treated patients compared to patients in the con
... Show MoreIn this research prepare membranes pure silicon carbide (SiC) as well as gas Alloy (ammonia) and using a laser was leaked membrane of glass flooring. To Drasesh optical properties of membranes prepared depending on the technique (Swanepoel) and Adhrt results obtained in general increased permeability pure silicon membranes
BACKGROUND: Tribulus terrestris has been commonly used in folk medicine to energize, vitalize and improve sexual function and physical performance in men and laboratory rats. OBJECTIVE: To study the effect of Tribulus terrestris on the number of Leydig cells. MATERIALS AND METHODS: Tribulus terrestris was given to mature male rats as an oral single herbal suspension in a dose of 2.0mg /1000gbody weight for 14 days to stimulate spermatogenesis. Formalin fixed paraffinembedded tissue sections were performed for histological, immunohistochemical and morphometrical studies. RESULTS: Histological study revealed wider seminiferous tubules and increased spermatocytes population with an increased sperm density inside the lumen of the tubul
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Antibiotic treatment of S.typhi is difficult as compared to treatment of acute infection. Antibiotic resistance carried against S.typhi by using 6 kinds of antibiotics from different classes, their results showed that all isolates were high resistance to Ampicillin (99%), Gentamicin (98%), Amikacin (79%) and less resistances Trimethoprim (55%) , Imipenem (60%) and Ceftriaxone(66%) .
The present study focused on the molecular detection of Wzx flippase, Wzy polymerase genes in some Salmonella typhi isolates, Samples were collected from typhoid patients by classical lab work. Antibiotics susceptibilit
... Show MoreSARS-CoV-2 stands for severe acute respiratory syndrome coronavirus 2 which is the causative agent of spreading coronavirus disease 2019 that is known as COVID-19 pandemic, the disease leads to severe acute respiratory illness. Matrix metalloproteinases- 9 (MMP-9) plays several important physiological functions. This enzyme could also be implicated in the "cytokine storm" in some way, which may represent one of the possible scianrios during coronavirus infection, in addition to its role in the mechanism of lung fibrosis on molecular basis.. The tissue inhibitors of metalloproteinase (TIMPs) are well characterized for controlling the activity of MMPs in extracellular matrix remodeling. They also considered as signaling molecules anal
... Show MoreBackground: Mitral regurgitation (MR) is the most commonly encountered valve lesion in modern clinical practice. Severe mitral regurgitation may cause systolic dysfunction. Left ventricular ejection fraction may not be an accurate measurement of LV function in patients with mitral insufficiency. Myocardial performance index (MPI) is a simple non invasive measure of myocardial function. Methods: The study involved 50 patients with valvular mitral regurgitation and 50 healthy subjects as a control group. Transthoracic echocardiography was carried out for all patients and control group. The echocardiographic measurements included left ventricular end diastolic and end systolic dimensions, left atrial diameter, ejection fraction (EF), and myoca
... Show Moreervical cancer is one of the most frequently diag nosed malignancies representing the fourth leading cause of cancer-related death in females’ worldwide, with approximately 500,000 new cases diagnosed and 280,000 deaths occurring each year. Mxi1, an antagonist of c-Myc, maps to human chromosome 10q24-q25, a region altered in a substantial fraction of prostate tumors, in prostate cancer, where a high frequency of loss and mutation of the MXI1 gene has been reported. The aim of present study was to find out the possible association of exon deletion of MXI1 gene with incidence of cervical abnormalities and cancers in some Iraqi married women. The present study include collection of 120 scraping cervical cells samples from women clinically di
... Show MoreAbstract:- Cyberspace is a new arena for conflict between international powers, especially since the cost of cyber-conflict is less than its traditional warfare counterparts regardless of the nature of the weapons used, whether traditional or non-traditional. Cyber conflict is necessarily based on strategies to deter, attack, and defend. The aim of the cybercrime conflict is to ensure the defensive sufficiency of the state, ensuring its national security and safeguarding its supreme interests. Despite Japan-China relations characterized by convergence and cooperation in post-Cold War economic spheres, Japan continues to retain the growing Chinese influence in East Asia. These variables prompted Japan to announce a hedging strategy due to un
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