scholarly journals Modification of Surface and Subsurface Properties of AA1050 Alloy by Shot Peening

Materials ◽  
2021 ◽  
Vol 14 (21) ◽  
pp. 6575
Author(s):  
Yasemin Yıldıran Avcu ◽  
Berkay Gönül ◽  
Okan Yetik ◽  
Fikret Sönmez ◽  
Abdulkadir Cengiz ◽  
...  
Keyword(s):  
Shot Peening ◽  
Material Removal ◽  
Crack Formation ◽  
Sample Surface ◽  
Al Alloy ◽  
Sem Images ◽  
Cross Sectional ◽  
Mean Size ◽  
The Mean ◽  
Main Deformation

AA1050 Al alloy samples were shot-peened using stainless-steel shots at shot peening (SP) pressures of 0.1 and 0.5 MPa and surface cover rates of 100% and 1000% using a custom-designed SP system. The hardness of shot-peened samples was around twice that of unpeened samples. Hardness increased with peening pressure, whereas the higher cover rate did not lead to hardness improvement. Micro-crack formation and embedment of shots occurred by SP, while average surface roughness increased up to 9 µm at the higher peening pressure and cover rate, indicating surface deterioration. The areal coverage of the embedded shots ranged from 1% to 5% depending on the peening parameters, and the number and the mean size of the embedded shots increased at the higher SP pressure and cover rate. As evidenced and discussed through the surface and cross-sectional SEM images, the main deformation mechanisms during SP were schematically described as crater formation, folding, micro-crack formation, and material removal. Overall, shot-peened samples demonstrated improved mechanical properties, whereas sample surface integrity only deteriorated notably during SP at the higher pressure, suggesting that selecting optimal peening parameters is key to the safe use of SP. The implemented methodology can be used to modify similar soft alloys within confined compromises in surface features.

scholarly journals Effects of Wet-Pressing and Cross-Linking on the Tensile Properties of Carbon Nanotube Fibers

Materials ◽  
2018 ◽  
Vol 11 (11) ◽  
pp. 2170 ◽  
Author(s):  
Hyunjung Cho ◽  
Jinwoo Lee ◽  
Haemin Lee ◽  
Sung-Hyun Lee ◽  
Junbeom Park ◽  
...  
Keyword(s):  
Carbon Nanotube ◽  
Cross Linking ◽  
Cross Sectional ◽  
Specific Strength ◽  
Wet Pressing ◽  
Mean Size ◽  
The Mean ◽  
The Cross ◽  
Carbon Nanotube Fibers ◽  
Physical And Chemical

To increase the strength of carbon nanotube (CNT) fibers (CNTFs), the mean size of voids between bundles of CNTs was reduced by wet-pressing, and the CNTs were cross-linked. Separate and simultaneous physical (roller pressing) and chemical methods (cross-linking) were tested to confirm each method’s effects on the CNTF strength. By reducing the fraction of pores, roller pressing decreased the cross-sectional area from 160 μm2 to 66 μm2 and increased the average load-at-break from 2.83 ± 0.25 cN to 4.41 ± 0.16 cN. Simultaneous injection of crosslinker and roller pressing augmented the cross-linking effect by increasing the infiltration of the crosslinker solution into the CNTF, so the specific strength increased from 0.40 ± 0.05 N/tex to 0.67 ± 0.04 N/tex. To increase the strength by cross-linking, it was necessary that the size of the pores inside the CNTF were reduced, and the infiltration of the solution was increased. These results suggest that combined physical and chemical treatment is effective to increase the strength of CNTFs.

scholarly journals Evaluation of occurrence of sesamoid bones in the lower extremity radiographs

2017 ◽  
Vol 7 (2) ◽  
pp. 11-14 ◽  
Author(s):  
Indu Ghimire ◽  
Surendra Maharjan ◽  
Ganesh Bahadur Pokharel ◽  
Kamal Subedi
Keyword(s):  
Knee Joint ◽  
Cross Sectional Study ◽  
University Teaching ◽  
Sesamoid Bone ◽  
Posterior Aspect ◽  
Cross Sectional ◽  
First Metatarsal ◽  
Sesamoid Bones ◽  
Mean Size ◽  
The Mean

The purpose of this study was to examine the plain AP radiograph of foot and lateral radiograph of knee in order to determine the prevalence and size of sesamoid bone in different part of foot and on the posterior aspect of the knee joint. A cross-sectional study was performed in Department of Radiology and Imaging, Tribhuvan University Teaching Hospital from July to September 2014. A total of 206 radiographs of foot (55) and knee (155) were collected. 121 (58.7%) were female and 85 (41.3%) were male. The most common site of sesamoid bone in foot was in the first metatarsal joint (96.4%) whereas the sesamoid bone in knee joint, fabella was found in 12.3% of total cases. The prevalence is more common in female than in male. The length and breadth of the sesamoid bones were measured and then area of bones was calculated. The size of medial and lateral sesamoid bone in the first MTP Joint was measured 0.6225 cm2 and 0.8261 cm2 respectively. The mean size of sesamoid bone of knee, fabella was 0.2818 cm2.

scholarly journals Histopathological and Clinical Features of Phyllodes Tumor in Hasan Sadikin during Period of 2012 - 2016

2018 ◽  
Vol 2 (2) ◽  
Author(s):  
Natasha A Harsas ◽  
Birgitta M Dewayani ◽  
Raden Yohana
Keyword(s):  
General Hospital ◽  
Medical Records ◽  
Secondary Data ◽  
Phyllodes Tumor ◽  
Tumor Diameter ◽  
Common Procedure ◽  
Cross Sectional ◽  
Mean Size ◽  
The Mean ◽  
Cross Sectional Design

Phyllodes tumor is a breast fibroepithelial lesion that rarely occurred. This type of tumor has tendency to recurre and metastasize. This study aimed to determine the features of phyllodes tumor in Hasan Sadikin General Hospital in period of 2012 to 2016, histopathologically and clinically. Descriptive study with cross sectional design was conducted in Department of Pathological Anatomy, Hasan Sadikin General Hospital, Bandung, from September 2016 to May 2017. Using total sampling, the secondary data are taken from medical records with the diagnosis of phyllodes tumor. From 88 samples taken, the mean age of the tumor occurrence is 45,56 years old and the mean size of tumor diameter is 10,98 cm. Tumor with benign type has the highest prevalence, with 54 cases reported. Mastectomy is the most common procedure performed on this tumor. There are 7 recurred patients and 1 patient with metastasis. As conclusions, phyllodes tumor is a rare tumor. In Hasan Sadikin general hospital, it mostly occurs in women aged 45 years old in the benign type. Mastectomy is often performed as a choice of surgical treatment.

A technique to prepare cross-sectional TEM specimens of semiconducting devices

1986 ◽  
Vol 44 ◽  
pp. 742-743
Author(s):  
A. K. Rai ◽  
P. P. Pronko
Keyword(s):  
Thin Films ◽  
Surface Region ◽  
Sample Surface ◽  
Specific Region ◽  
Cross Sectional ◽  
Thin Sections ◽  
The Past ◽  
Device Structures ◽  
Ion Implanted

Several techniques have been reported in the past to prepare cross(x)-sectional TEM specimen. These methods are applicable when the sample surface is uniform. Examples of samples having uniform surfaces are ion implanted samples, thin films deposited on substrates and epilayers grown on substrates. Once device structures are fabricated on the surfaces of appropriate materials these surfaces will no longer remain uniform. For samples with uniform surfaces it does not matter which part of the surface region remains in the thin sections of the x-sectional TEM specimen since it is similar everywhere. However, in order to study a specific region of a device employing x-sectional TEM, one has to make sure that the desired region is thinned. In the present work a simple way to obtain thin sections of desired device region is described.

Comparison of Ion-Milling Techniques For Cross-Sectional TEM of Semiconductors

1985 ◽  
Vol 43 ◽  
pp. 166-167
Author(s):  
Julia T. Luck ◽  
C. W. Boggs ◽  
S. J. Pennycook
Keyword(s):  
Analytical Techniques ◽  
Sample Surface ◽  
Ion Milling ◽  
Cross Sectional ◽  
Reliable Technique ◽  
Near Surface ◽  
Transmission Electron ◽  
Thin Region ◽  
Transient Thermal

The use of cross-sectional Transmission Electron Microscopy (TEM) has become invaluable for the characterization of the near-surface regions of semiconductors following ion-implantation and/or transient thermal processing. A fast and reliable technique is required which produces a large thin region while preserving the original sample surface. New analytical techniques, particularly the direct imaging of dopant distributions, also require good thickness uniformity. Two methods of ion milling are commonly used, and are compared below. The older method involves milling with a single gun from each side in turn, whereas a newer method uses two guns to mill from both sides simultaneously.

Relationship of Sense of Coherence to Other Psychosocial Indices

2004 ◽  
Vol 20 (4) ◽  
pp. 227-236 ◽  
Author(s):  
Sara Holmberg ◽  
Anders Thelin ◽  
Eva-Lena Stiernström
Keyword(s):  
Social Support ◽  
Psychosocial Factors ◽  
Sense Of Coherence ◽  
Living Conditions ◽  
Strong Negative Correlation ◽  
Cross Sectional ◽  
Positive Correlation ◽  
Work Related ◽  
Job Demand ◽  
The Mean

Summary: The concept of “sense of coherence” (SOC) has been widely recognized since it was first introduced by Antonovsky. The originality and usefulness of the SOC scale and its relation to other psychosocial measures has been the subject of lively debate. The aim of this paper was to test for associations between SOC and work-related psychosocial factors (mainly the Job Demand-Control model), general living conditions, education, and social network factors. Cross-sectional data from a population-based sample of 1782 rural males from nine counties in Sweden were analyzed with a multiple regression technique. The subjects were occupationally active at inclusion and the mean age was 50 years (range 40-60). SOC was assessed with the original 29-item questionnaire. Psychosocial variables and lifestyle factors were assessed using questionnaires and structured interviews. The mean SOC among the subjects was 152.3 (standard deviation, 19.4). A strong negative correlation was found between SOC and job demand, whereas a positive correlation with job control was demonstrated. A positive correlation with general living conditions and with social support was also found. However, there was no correlation to education and occupation. Thus, SOC was shown to be strongly correlated to work-related psychosocial factors and social support, but independent of sociodemographic factors.

Age related volume of cadaver-prostates in Bangladesh

1970 ◽  
Vol 4 (2) ◽  
pp. 74-77
Author(s):  
Rukshana Ahmed ◽  
Shamim Ara
Keyword(s):  
Prostate Gland ◽  
Age Groups ◽  
Clinical Settings ◽  
Cross Sectional ◽  
Medical College ◽  
Age Related ◽  
Group A ◽  
Key Words Prostate ◽  
The Mean ◽  
Group B

Pathological changes in the prostate gland occur commonly with advancing age including inflammation, atrophy, hyperplasia and carcinoma and a change in volume is also evident. Estimation of volume of prostate may be useful in a variety of clinical settings. A cross-sectional descriptive study was designed to see the changes in volume of the prostate with advancing age and done in the Department of Anatomy, Dhaka Medical College, Dhaka from August 2006 to June 2007. The study was performed on 70 post-mortem human prostates collected from the unclaimed dead bodies that were under examination in the Department of Forensic Medicine, Dhaka Medical College, Dhaka. The samples were divided into three age groups; group A (10-20 years), group B (21-40 years) and group C (41-70 years). Volume of the sample was measured by using the ellipsoid formula. The mean ± SD volume of prostate was 7.68 ± 3.64 cm3 in group A, 10.61 ± 3.99 cm3 in group B and 15.40 ± 6.31 cm3 in group C. Mean difference in volume between group A and group C, group B and group C were statistically significant (p<0.001). Statistically significant positive correlation was found between age and volume of prostate (r = + 0.579, p < 0.001). Key Words: Prostate; volume; Bangladeshi. DOI: 10.3329/imcj.v4i2.6501Ibrahim Med. Coll. J. 2010; 4(2): 74-77

Brief Overview and Experience of Visual Evoked Potential of First 67 cases at Referral Neuroscience Hospital in Bangladesh

2020 ◽  
Vol 6 (2) ◽  
pp. 74-77
Author(s):  
Mohammad Enayet Hussain ◽  
Bithi Debnath ◽  
AFM Al Masum Khan ◽  
Md Ferdous Mian ◽  
Md Nahidul Islam ◽  
...  
Keyword(s):  
Multiple Sclerosis ◽  
Optic Neuritis ◽  
Clinical Diagnosis ◽  
Optic Neuropathy ◽  
Cross Sectional Study ◽  
P Value ◽  
Pattern Reversal ◽  
Cross Sectional ◽  
The Mean ◽  
Visual Evoked

Background: The visual evoked potentials (VEP) is a valuable tool to document occult lesions of the central visual channels especially within the optic nerve. Objectives: The purpose of the present study was to observe the findings of first few cases of VEP done in the neurophysiology department of the National Institute of Neurosciences (NINS), Dhaka, Bangladesh. Methodology: This cross-sectional study was conducted in the Department of Neurophysiology at the National Institute of Neurosciences and Hospital, Dhaka, Bangladesh from September 2017 to March 2020. All patients referred to the Neurophysiology Department of NINS for VEP were included. Pattern reversal VEPs were done using standard protocol set by International Federation of Clinical Neurophysiology (IFCN). Results: The mean age of the study population was 30.70 (±12.11) years (6-68 years) with 31 (46.3%) male and 36 (53.7%) female patients. The mean duration of illness was 8.71 (±1.78) months (3 days- 120 months). Most common presenting symptom was blurring of vision (37.3%) and dimness of vision (32.8%). Patterned VEP revealed mixed type (both demyelinating and axonal) of abnormality in most cases [29(43.35)]. The most common clinical diagnosis was multiple sclerosis (29.85%) and optic neuropathy (26.87%). In the clinically suspected cases of multiple sclerosis, optic neuropathy and optic neuritis most of the cases of VEP were abnormal and the p value is 0.04 in optic neuropathy and optic neuritis. Conclusion: The commonest presentation of the patients in this series were blurring of vision and dimness of vision. The most common clinical diagnosis for which VEP was asked for, was optic neuritis and multiple sclerosis. Most abnormalities were of mixed pattern (demyelinating and axonal). Journal of National Institute of Neurosciences Bangladesh, 2020;6(2): 74-77

Sonographic Assessment of Amniotic Fluid Volume using Single Deepest Pocket (SDP) among Igbo Women with Uncomplicated Singleton Pregnancies.

2019 ◽  
Vol 2 (1) ◽  
pp. 1-18
Author(s):  
Chijioke Okeudo ◽  
B.U. Ezem
Keyword(s):  
Amniotic Fluid ◽  
Gestational Age ◽  
Cross Sectional Study ◽  
Fluid Volume ◽  
Singleton Pregnancy ◽  
Cross Sectional ◽  
South Eastern ◽  
Amniotic Fluid Volume ◽  
The Mean ◽  
Singleton Pregnancies

Background: The amniotic fluid is fundamental for proper fetal development and growth. Ultrasound visualization of the amniotic fluid permits both subjective and objective estimates of the amniotic fluid. Objective: The objective of this study was to determine the reference values of normal single deepest pocket (SDP) – upper and lower limits, mean SDP and variation of the SDP with gestational age among Igbo women of South-Eastern Nigeria extraction carrying uncomplicated singleton pregnancy. Methodology: This was a prospective cross sectional study involving 400 women carrying uncomplicated singleton pregnancies and who were sure of the date of the first day of their last menstrual period. The single deepest pocket / maximum vertical pool were determined once at presentation at the hospital.. The study was conducted from January 1st to December 31st 2015. The second author carried out all the scanning. The SDP was obtained. Results: The womens’ mean and median ages were the same at 28 years. The gestational age range of the pregnancies was 14-41 weeks. The mean SDP was 5.8cm, while the 5th and 95th percentiles were 3.3cm and 8.5cm respectively. There was no difference in the mean SDP in both term and preterm. There was irregular but continuous rise of mean SDP to a peak of 6.8cm at gestational age of 39 weeks. In conclusion, the participants had a mean SDP of 5.8cm. There was also a positive correlation between SDP and Gestational age. We therefore recommend a longitudinal study to assess perinatal outcome and abnormal amniotic fluid volume among Igbo women of South-Eastern Nigeria. Key words: Single Deepest Pocket, Uncomplicated Singleton Pregnancy, Igbo Women.

Determination of the metal toughness components in impact-bending test

2018 ◽  
Vol 84 (12) ◽  
pp. 68-72
Author(s):  
A. B. Maksimov ◽  
I. P. Shevchenko ◽  
I. S. Erokhina
Keyword(s):  
Crack Growth ◽  
Specific Energy ◽  
Crack Formation ◽  
Crack Nucleation ◽  
Scale Effects ◽  
Linear Equations ◽  
Bending Test ◽  
Cross Sectional ◽  
Two Samples ◽  
Sample Width

A method for separating the work of impact into two parts - the work of the crack nucleation and that of crack growth - which consists in testing two samples with the same stress concentrators and different cross-sectional dimensions at the notch site is developed. It is assumed that the work of crack nucleation is proportional to the width of the sample face on which the crack originates and the specific energy of crack formation, whereas the work of the crack growth is proportional to the length of crack development and the specific crack growth energy. In case of the sample fracture upon testing, the crack growth length is assumed equal to the sample width. Data on the work of fracture of two samples and their geometrical dimensions at the site of the notch are used to form a system of two linear equations in two unknowns, i.e., the specific energy of crack formation and specific energy of crack growth. The determined specific energy values are then used to calculate the work of crack nucleation and work of crack growth. The use of the analytical method improves the accuracy compared to graphical - extrapolative procedures. The novelty of the method consists in using one and the same form of the notch in test samples, thus providing the same conditions of the stress-strain state for crack nucleation and growth. Moreover, specimens with different cross-section dimensions are used to eliminate the scale effects. Since the specific energy of the crack nu-cleation and specific energy of the crack growth are independent of the scale factor, they are determined only by the properties of the metal. Introduction the specific energy of crack formation and growth makes possible to assign a specific physical meaning to the fracture energy.

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