The Influence of Pearlite Volume Fraction on Rayleigh Wave Propagation in A572 Grade 50 Steel

The acoustoelastic effect is the interaction between ultrasonic wave velocity and stress. To estimate the stress a perturbation signal is introduced and the shift in time of flight is measured at the receiving location. In addition to the stress, the wave velocity can be affected by the amount of phases in the material’s microstructure. This study investigates the changes in Rayleigh wave velocity for A572 grade 50 steel as a function of stress and pearlite phase volume fraction. In order to obtain different amounts of pearlite the samples are heat treated at 970 °C for time durations of 30 min, 1 hour, 2 hours and 4 hours and then furnace cooled. The acoustoelastic coefficient for 0.5 and 1 MHz perturbation frequency is calculated by uniaxial loading of each heat treated plate while measuring ultrasonic wave velocity. The results are compared for pearlite phase volume fraction obtained from optical microscopy and hardness measurements

Dentigerous cyst associated with an impacted anterior maxillary supernumerary tooth (mesiodens): A case report

Background: Dentigerous cysts are commonly seen in association with third molars and maxillary canines. Only 5–6% of dentigerous cysts are associated with supernumerary teeth. We report a rare case of dentigerous cyst associated with an impacted anterior maxillary supernumerary tooth (mesiodens). Case Presentation: A 30-year-old male reported to our Department of Oral Medicine, School of Dentistry at Hamedan University of Medical Sciences, with chief complaint of a painless swelling in the anterior upper jaw (in the region of incisors) for a duration of 3 month. At the time of his presentation, his medical history was unremarkable, with no systemic problems and no report of pain. Conclusion: Although the association of dentigerous cyst with an impacted supernumerary tooth (mesiodens) is rare, prevention of harmful complications as developmental cyst, early diagnosis and treatment is necessary. The standard treatment is Enucleation. Keywords: Dentigerous cysts; Mesiodens; Supernumerary teeth

Fibrosarcoma of mandible: A case report

Fibrosarcomas is an uncommon connective tissue growth that rises from the proliferation of malignant fibroblasts. Local recurrence is frequent, but metastasis is rare. About 0.05% of cases are affected in the head and neck. We report a case of mandibular fibrosarcoma in a 30-year-old man who presented with intraoral swelling in the ridge of the left mandibular alveolus. Histopathology showed the proliferation of malignant fibroblast cells arranged in a classic herringbone pattern. Keywords: Fibrosarcoma; Fibroblast; Malignancy; Lower jaw; Spindle cell tumor; Oral cavity

Stress Quantification of Complexly Loaded Structural Components using Acoustoelasticity

The ultrasonic monitoring of steels and other structural materials relies on measuring the velocity of elastic waves, which varies with the existing stress state in the material—a phenomenon known as acoustoelasticity. This research is focused on applying the acoustoelastic method for stress analysis to thick steel plates (9-12 mm) of the type commonly used for gusset plates of steel truss bridges, where shear stress is significant. The acoustoelastic coefficients are determined in thick steel plates in normal, orthogonal, and angled directions using an array of ultrasonic sensors. A three-dimensional material model is developed which includes Murnaghan hyper-elasticity and can determine the effects of plate thickness and excitation frequency on the acoustoelastic coefficients. This model is experimentally validated by tensile loading of a thick steel plate by measuring the ultrasonic signals in three directions. Numerical and experimental results agree within the measurement uncertainties of each method. The 1.0 MHz ultrasonic frequency has the highest resolution for measuring normal and shear stresses in plates typically used in highway bridges. Additionally, the ultrasonic velocity and stress equation is modified to add the shear effect in addition to normal stresses. As a result, the theory of acoustoelasticity in a homogenous and isotropic plate is developed for the presence of multi-directional stress in a cross section considering normal and shear stresses. The resulting analytical equations are solved to understand the influence of shear stress on the acoustoelastic coefficients

The relationship between Business Process Re-engineering and learning organization

This article explains the relationship between business process reengineering and learning organizations. As business process reengineering and learning organizations both are techniques to support changing in organizations, this research offers a model which develops an optimized combination of the two methods and also concentrates to both their original purpose. In following, the main aim of doing this research is described and also claimed the main hypothesis of the research that business process reengineering and learning organizations can have a synergic relationship. In the research descriptive methodology has been used and its statistical society is generally software industry in Iran and specifically four software company which work on developing , supporting and training of software in Tehran. The designed questionnaire was distributed between top executives, vice presidents, project managers, middle managers, process experts and trainers of the companies and totally gathered 135 of them. The results of this research suggest that the Organization's movement regarding to business processing engineering or learning organization, helps the organization to accept changes from the other path and affects the success of the other approach. This research stops dedicated view point of users, who are looking for major changes' in their organization, towards the current approach

Adsorption Of Ammonium Ions Onto Multi-Walled Carbon Nanotubes

Multi-walled carbon nanotubes (MWCNTs) surfaces have been characterized by FTIR and SEM techniques. The adsorption performance of MWCNTs was investigated for the removal of ammonium ions from wastewater. The effect of contact time, temperature and initial ions concentration on the adsorption of ammonium ions by MWCNTs were studied and optimized. The results showed a high adsorption capacity of 129 mg/g according to Langmuir isotherm model and removal efficiency of 95%. In addition, the adsorption kinetic and equilibrium data were fitted to the pseudo–second–order model. The potential application of MWCNTs for adsorption of ammonium ions from wastewater was successfully accomplished using a batch adsorption technique

The Influence of Pearlite Volume Fraction on Rayleigh Wave Propagation in A572 Grade 50 Steel

The acoustoelastic effect is the interaction between ultrasonic wave velocity and stress. To estimate the stress a perturbation signal is introduced and the shift in time of flight is measured at the receiving location. In addition to the stress, the wave velocity can be affected by the amount of phases in the material’s microstructure. This study investigates the changes in Rayleigh wave velocity for A572 grade 50 steel as a function of stress and pearlite phase volume fraction. In order to obtain different amounts of pearlite the samples are heat treated at 970 °C for time durations of 30 min, 1 hour, 2 hours and 4 hours and then furnace cooled. The acoustoelastic coefficient for 0.5 and 1 MHz perturbation frequency is calculated by uniaxial loading of each heat treated plate while measuring ultrasonic wave velocity. The results are compared for pearlite phase volume fraction obtained from optical microscopy and hardness measurements.</p

Synthesis of Artemether-Loaded Albumin Nanoparticles and Measurement of Their Anti-Cancer Effects

Colorectal cancer is the third most common cancer in the world. Due to the side effects of common treatments such as chemotherapy and radiotherapy, the use of herbal medicines has received much attention. Artemether (ARM) is an herbal medicine derived from artemisinin, which has many anti-tumor properties. However, factors such as low solubility and short half-life have limited the use of artemether in clinical practice. In this study, we aimed to reduce these limitations by encapsulating artemether in human serum albumin (HSA). The hydrodynamic diameter and the zeta potential value of ARM-ALB nanoparticles (NPs) were 171.3 &plusmn; 5.88 nm and &minus;19.1 &plusmn; 0.82 mV, respectively. Comparison of the effect of free and encapsulated artemether on CT 26 cell line showed that the use of artemether in capsulated form can reduce the effective concentration of the drug. Additionally, in vivo studies have also shown that albumin&ndash;artemether nanoparticles can control tumor growth by increasing the production of cytokine IFN-&gamma; and decreasing the production of IL4. Therefore, ARM-ALB nanoparticles have greater anti-tumor effects than free artemether

A theoretical investigation of the N2O + SO2 reaction on surfaces of P-doped C60 nanocage and Si-doped B30N30 nanocage

The mechanism of N2O reduction via SO2 on surfaces of P-doped C60 and Si-doped B30N30 by density functional theory were investigated. The P and Si adsorption energies on surface of C60 and B30N30 were calculated to be −287.5 and −312.1 kcal/mol, respectively. The decomposition of C60-P-N2O and B30N30-Si-N2O and reduction of C60-P-O∗ and B30N30-Si-O∗ by SO2 molecule were investigated. The B30N30-Si-O∗ has lower activation energy and has more negative ΔGad rather than C60-P-O∗ and therefore the process of B30N30-Si-O∗ + SO2 → B30N30-Si + SO3 was spontaneous more than C60-P-O∗ + SO2 → C60-P + SO3 from thermodynamic view point. Results show that activation energies for B30N30-Si-O∗ + N2O → B30N30-Si-O2 + N2 and C60-P-O∗ + N2O → C60-P-O2 + N2 reactions were 33.23 and 35.82 kcal/mol, respectively. The results show that P-doped C60 and Si-doped B30N30 can be observed as a real catalysts for the reduction of N2O. Keywords: Atom doping, Catalyst, Nanocage, Adsorption, N2O reductio

The Role of Student Stressors in Predicting Procrastination and Academic Burnout among Nursing Students

Introduction: Nursing is one of the disciplines which may cause a lot of tension for students. The aim of this study was to investigate the role of student stressors in predicting procrastination and academic burnout among nursing students. Methods: This research was a descriptive correlational study. Statistical population consisted of all nursing students of Arak University of Medical Sciences in 2013-14 academic years the sample included 270 participants who were selected through available sampling. The data was collected through procrastination and academic burnout and student stressors questionnaires. The collected data were analyzed using Pearson correlation coefficient and regression analysis. Results: Pearson correlation coefficient showed that there was a significant positive relationship between student stressors and procrastination and academic burnout. Regression analysis also indicated that stressors associated with academic conditions, educational environment, graduation and dormitory environment predicted 11.8% of students’ academic burnout variations and 18.6% of procrastination variations. Conclusion: The results of this study revealed the role of student stressors in procrastination and academic burnout among nursing students which may suggest that student stressors play an important role in the incidence and escalation of procrastination and academic burnout in nursing students