Search results for: skin damage

Authors: Abdulaziz Alakeel, Abdulrahman Alomair, Mohammed Fouda

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Introduction: Methotrexate (MTX) is an antimetabolite used to treat multiple conditions, including neoplastic diseases, severe psoriasis, and rheumatoid arthritis. Skin cancer is the out-of-control growth of abnormal cells in the epidermis, the outermost skin layer, caused by unrepaired DNA damage that triggers mutations. These mutations lead the skin cells to multiply rapidly and form malignant tumors. The aim of this review is to evaluate the risk of skin cancer associated with the use of methotrexate and to suggest regulatory recommendations if required. Methodology: Signal Detection team at Saudi Food and Drug Authority (SFDA) performed a safety review using National Pharmacovigilance Center (NPC) database as well as the World Health Organization (WHO) VigiBase, alongside with literature screening to retrieve related information for assessing the causality between skin cancer and methotrexate. The search conducted in July 2020. Results: Four published articles support the association seen while searching in literature, a recent randomized control trial published in 2020 revealed a statistically significant increase in skin cancer among MTX users. Another study mentioned methotrexate increases the risk of non-melanoma skin cancer when used in combination with immunosuppressant and biologic agents. In addition, the incidence of melanoma for methotrexate users was 3-fold more than the general population in a cohort study of rheumatoid arthritis patients. The last article estimated the risk of cutaneous malignant melanoma (CMM) in a cohort study shows a statistically significant risk increase for CMM was observed in MTX exposed patients. The WHO database (VigiBase) searched for individual case safety reports (ICSRs) reported for “Skin Cancer” and 'Methotrexate' use, which yielded 121 ICSRs. The initial review revealed that 106 cases are insufficiently documented for proper medical assessment. However, the remaining fifteen cases have extensively evaluated by applying the WHO criteria of causality assessment. As a result, 30 percent of the cases showed that MTX could possibly cause skin cancer; five cases provide unlikely association and five un-assessable cases due to lack of information. The Saudi NPC database searched to retrieve any reported cases for the combined terms methotrexate/skin cancer; however, no local cases reported up to date. The data mining of the observed and the expected reporting rate for drug/adverse drug reaction pair is estimated using information component (IC), a tool developed by the WHO Uppsala Monitoring Centre to measure the reporting ratio. Positive IC reflects higher statistical association, while negative values translated as a less statistical association, considering the null value equal to zero. Results showed that a combination of 'Methotrexate' and 'Skin cancer' observed more than expected when compared to other medications in the WHO database (IC value is 1.2). Conclusion: The weighted cumulative pieces of evidence identified from global cases, data mining, and published literature are sufficient to support a causal association between the risk of skin cancer and methotrexate. Therefore, health care professionals should be aware of this possible risk and may consider monitoring any signs or symptoms of skin cancer in patients treated with methotrexate.

Keywords: methotrexate, skin cancer, signal detection, pharmacovigilance

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Authors: India Sanders, Jeffrey Sherman

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Colorism has been a persistent and ingrained issue in the history of the United States, with far-reaching consequences that continue to affect various aspects of daily life, institutional policies, public spaces, economic structures, and social norms. This complex problem has had a particularly profound impact on the African-American community, shaping how they are perceived and treated within society at large. The prevalence of negative stereotypes surrounding African Americans can lead to severe repercussions such as discrimination and mental health disparities. The effects of such biases can also materialize in diverse forms, impacting the well-being and livelihoods of individuals within this community. Current research has examined how people from different racial groups perceive different skin tones of Black people, looking at the cognitive processes that manifest through categorization and stereotypes. Additionally, studies observed consequences related to colorism and how it directly affects those with darker versus lighter skin tones. However, not much research has been conducted on the influence of stereotypes associated with various skin tones. In the present study, it is hypothesized that participants in Group A will rate positive stereotypes associated with lighter skin tones significantly higher than positive stereotypes associated with darker skin tones. It is also hypothesized that participants in Group B will rate negative stereotypes associated with darker skin tones significantly higher than negative stereotypes associated with lighter skin tones. For this study, a quantitative study on stereotypes of skin tone representation within the African-American community will be conducted. Participants will rate the accuracy of various visual representations within mass media of African Americans with light skin tones and dark skin tones using a Likert scale. Participants will also be provided a questionnaire further examining the perception of stereotypes and how this affects their interactions with African Americans with lighter versus darker skin tones. The purpose of this study is to investigate the impact of skin tone portrayals on African Americans, including associated stereotypes and societal perceptions. It is expected that participants will more likely associate negative stereotypes with African Americans who have darker skin tones, as this is a common and reinforced viewpoint in the cultural and social system.

Keywords: colorism, discrimination, racism, stereotype

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Authors: Abdullah Saeidi, Aydin Gülses, Christan Flörke

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Skin cancer of the face region is the most common type of malignancy and surgical excision is the preferred approach. However, the clinical long term results reported in the literature are still controversial. Objectives: To describe; 1. Demographical characteristics 2. Affected site, distribution and TNM classification regarding tumor type 3. Surgical aspects • Surgical removal: excision principles, safety margins, the need for secondary resection, primary reconstruction/ defect closure, anesthesia protocol, duration of hospital stay (if any) • Secondary intervention for defect closure/reconstruction: Flap technique, anesthesia protocol, duration of hospital stay (if any), postoperative wound management etc. 4. Tumor recurrences 5. Clinical outcomes 6. Studying the possible therapy approach throw Biostatistical relation and correlation between multiple Histological, diagnostics and clinical Faktors. following surgical ablation of the skin cancer of the head and neck region. Methods: Selection and statistical analysis of medical records of patients who had admitted to the Department of Oral and Maxillofacial Surgery, Universitätsklinikum Schleswig Holstein, Campus Kiel during the period of 2015-2019 will be retrospectively evaluated. Data will be collected via ORBIS Information-Management-System (ORBIS AG, Saarbrücken, Germany).

Keywords: non melanoma skin cancer, face skin cancer, skin reconstruction, non melanoma skin cancer recurrence, non melanoma skin cancer metastases

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Authors: Shaira L. Kee, Michael Aaron G. Sy, Myles Joshua T. Tan, Hezerul Abdul Karim, Nouar AlDahoul

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Skin diseases are considered the fourth most common disease, with melanoma and non-melanoma skin cancer as the most common type of cancer in Caucasians. The alarming increase in Skin Cancer cases shows an urgent need for further research to improve diagnostic methods, as early diagnosis can significantly improve the 5-year survival rate. Machine Learning algorithms for image pattern analysis in diagnosing skin lesions can dramatically increase the accuracy rate of detection and decrease possible human errors. Several studies have shown the diagnostic performance of computer algorithms outperformed dermatologists. However, existing methods still need improvements to reduce diagnostic errors and generate efficient and accurate results. Our paper proposes an ensemble method to classify dermoscopic images into benign and malignant skin lesions. The experiments were conducted using the International Skin Imaging Collaboration (ISIC) image samples. The dataset contains 3,297 dermoscopic images with benign and malignant categories. The results show improvement in performance with an accuracy of 88% and an F1 score of 87%, outperforming other existing models such as support vector machine (SVM), Residual network (ResNet50), EfficientNetB0, EfficientNetB4, and VGG16.

Keywords: deep learning - VGG16 - efficientNet - CNN – ensemble – dermoscopic images - melanoma

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Authors: Lucas Bernardes Naves, Luis Almeida

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The paper includes a review concerning the use of some composites including poly(lactide-co-glycolide) (PGLA), zeolite and Gadopentetic acid (Gd-DTPA) loaded chitosan nanoparticles (Gd-nanoCPs) in order to establish a new alternative for the treatment of Melanoma Skin Cancer. The main goal of this paper it to make a review of what scientist have done in the last few years, as well as to propose a less invasive therapy for skin cancer, by using Hydrocolloid, based on PLGA coated with Gd-nanoCPs for Neutron Capture Therapy.

Keywords: cancer therapy, dressing polymers, melanoma, wound healing

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Authors: Ammar Maziz, Mostapha Tarfaoui, Said Rechak

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The high mechanical performance of composite pipes can be adversely affected by their low resistance to impact loads. Loads in dynamic origin are dangerous and cause consequences on the operation of pipes because the damage is often not detected and can affect the structural integrity of composite pipes. In this work, an advanced 3-D finite element (FE) model, based on the use of intralaminar damage models was developed and used to predict damage under low-velocity impact. The performance of the numerical model is validated with the confrontation with the results of experimental tests. The results show that at low impact energy, the damage happens mainly by matrix cracking and delamination. The model capabilities to simulate the low-velocity impact events on the full-scale composite structures were proved.

Keywords: composite materials, low velocity impact, FEA, dynamic behavior, progressive damage modeling

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Authors: Gholamreza Ghodrati Amiri, Mojtaba Jafarian Abyaneh, Ali Zare Hosseinzadeh

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This paper presents an effective model updating strategy for damage localization and quantification in frames by defining damage detection problem as an optimization issue. A generalized version of the Modal Residual Force (MRF) is employed for presenting a new damage-sensitive cost function. Then, Grey Wolf Optimization (GWO) algorithm is utilized for solving suggested inverse problem and the global extremums are reported as damage detection results. The applicability of the presented method is investigated by studying different damage patterns on the benchmark problem of the IASC-ASCE, as well as a planar shear frame structure. The obtained results emphasize good performance of the method not only in free-noise cases, but also when the input data are contaminated with different levels of noises.

Keywords: frame, grey wolf optimization algorithm, modal residual force, structural damage detection

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Authors: Mohd Ritzman Abdul Karim, Zhaohui Huang

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A current focus in seismic engineering practice is the development of seismic design approach that focuses on the performance-based design. Performance-based design aims to design the structures to achieve specified performance based on the damage limit states. This damage limit is more restrictive limit than life safety and needs to be carefully estimated to avoid damage in piers due to failure in transverse reinforcement. In this paper, a different perspective of damage limit states has been explored by integrating two damage control material limit state, concrete and reinforcement by introduced parameters such as expected yield stress of transverse reinforcement where peak tension strain prior to bar buckling is introduced in a recent study. The different perspective of damage limit states with modified yield displacement and the modified plastic-hinge length is used in order to predict damage-control target displacement for reinforced concreate (RC) bridge pier. Three-dimensional (3D) finite element (FE) model has been developed for estimating damage target displacement to validate proposed damage limit states. The result from 3D FE analysis was validated with experimental study found in the literature. The validated model then was applied to predict the damage target displacement for RC bridge pier and to validate the proposed study. The tensile strain on reinforcement and compression on concrete were used to determine the predicted damage target displacement and compared with the proposed study. The result shows that the proposed damage limit states were efficient in predicting damage-control target displacement consistent with FE simulations.

Keywords: damage-control target displacement, damage limit states, reinforced concrete bridge pier, yield displacement

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Authors: Mohamed Elassaly

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The damage status of RC buildings is greatly influenced by the characteristics of the imposed ground motion. Peak Ground Acceleration and frequency contents are considered the main two factors that affect ground motion characteristics; hence, affecting the seismic response of RC structures and consequently their damage state. A detailed investigation on the combined effects of these two factors on damage assessment of RC buildings, is carried out. Twenty one earthquake records are analyzed and arranged into three groups, according to their frequency contents. These records are used in an investigation to define the expected damage state that would be attained by RC buildings, if subjected to varying ground motion characteristics. The damage assessment is conducted through examining drift ratios and damage indices of the overall structure and the significant structural components of RC building. Base and story shear of RC building model, are also investigated, for cases when the model is subjected to the chosen twenty one earthquake records. Nonlinear dynamic analyses are performed on a 2-dimensional model of a 12-story R.C. building.

Keywords: damage, frequency content, ground motion, PGA, RC building, seismic

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Authors: Sun Fan, Wu Xiaoguang, Fang Miaomiao, Wei Chi

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The degree of damage to the support is simulated by finite element software, and its influence on the static and dynamic effects of the bridge structure is analyzed. Four working conditions are selected for the study of bearing damage impact: the bearing is intact (condition 1), the bearing damage coefficient is 0.8 (condition 2), the bearing damage coefficient is 0.6 (condition 3), and the bearing damage coefficient is 0.4 (Working Condition 4). The effect value of the bridge structure under each working condition is calculated, and the simple-supported girder bridge and continuous girder bridge with typical spans are taken as examples to analyze the overall change of the bridge structure after the bearing completely fails.

Keywords: bridge bearing damage, dynamic response, finite element analysis, load conditions

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Authors: Hazleen Anuar, Nur Aimi Mohd Nasir

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Durian skin is a newly explores natural fibre potentially reinforced polyolefin for diverse applications. In this work, investigation on the effect of coupling agent, maleic anhydride polypropylene (MAPP) on the mechanical, morphological and thermal properties of polypropylene (PP) reinforced with durian skin fibre (DSF) was conducted. The presence of 30 wt% DSF significantly reduced the tensile strength of PP-DSF composite. Interestingly, even though the same trend goes to PP-DSF with the presence of MAPP, the reduction is only about 4% relative to unreinforced PP and 18% higher than PP-DSF without MAPP (untreated composite or UTC). The used of MAPP in treated composite (TC) also increased the tensile modulus, flexural properties and degradation temperature. The enhanced mechanical properties are consistent with good interfacial interaction as evidenced under scanning electron microscopy.

Keywords: durian skin fiber, coupling agent, mechanical properties, thermogravimetry analysis

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Authors: Huixin Wei, Shibin Wang, Linan Li, Lei Zhou, Xinhao Tu

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Facial skin is a biomedical material with complex mechanical properties of anisotropy, viscoelasticity, and hyperelasticity. The mechanical properties of facial skin are crucial for a number of applications including facial plastic surgery, animation, dermatology, cosmetic industry, and impact biomechanics. Skin is a complex multi-layered material which can be broadly divided into three main layers, the epidermis, the dermis, and the hypodermis. Collagen fibers account for 75% of the dry weight of dermal tissue, and it is these fibers which are responsible for the mechanical properties of skin. Many research on the anisotropic mechanical properties are mainly concentrated on in vitro, but there is a great difference between in vivo and in vitro for mechanical properties of the skin. In this study, we presented a method to measure the mechanical properties of facial skin in vivo. Digital image correlation (DIC) and indentation tests were used to obtain the experiment data, including the deformation of facial surface and indentation force-displacement curve. Then, the experiment was simulated using a finite element (FE) model. Application of Computed Tomography (CT) and reconstruction techniques obtained the real tissue geometry. A three-dimensional FE model of facial skin, including a bi-layer system, was obtained. As the epidermis is relatively thin, the epidermis and dermis were regarded as one layer and below it was hypodermis in this study. The upper layer was modeled as a Gasser-Ogden-Holzapfel (GOH) model to describe hyperelastic and anisotropic behaviors of the dermis. The under layer was modeled as a linear elastic model. In conclusion, the material properties of two-layer were determined by minimizing the error between the FE data and experimental data.

Keywords: facial skin, indentation test, finite element, digital image correlation, computed tomography

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Authors: Valerian Omsarashvili, Nino Jamrishvili

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Georgia is one of the hail-dangerous countries of world. The work on action on hail processes in Georgia was conducted in 1960-1989 (East Georgia) over the total area of approximately 1.2 million hectares with average positive economic effect near 75 %. In 2015 in East Georgia, the anti-hail service was restored. Therefore, for the estimation of the effectiveness of action on the hail processes at present, arose the need for the detailed analysis of damage from the hail in the past. The work presents the analysis of the data about the number of days with the hail, the areas of damage of agricultural crops (general and to 100 %), and also the economic damage from the hail, of the caused loss to agricultural crops on the territories land of 123 separate populated areas of into 1982 and 1984-1989. In particular, on the average to one populated area, the total area of agricultural crops damaged from the hail was approximately 140 hectares, to 100% damage - 60 hectares, economic damage - 120 thousand US dollars. The corresponding maps of the distribution of the damaged areas on the investigated territory with the use of GIS-technologies are obtained.

Keywords: damage to agricultural crops, hail, Georgia, economic damage

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Authors: Hadi Rad

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Unrestricted somatic stem cells (USSCs) loaded in nanofibrous PHBV scaffold can be used for skin regeneration when grafted into full-thickness skin defects of rats. Nanofibrous PHBV scaffolds were designed using electrospinning method and then, modified with the immobilized collagen via the plasma method. Afterward, the scaffolds were evaluated using scanning electron microscopy, physical and mechanical assays. In this study; nanofibrous PHBV scaffolds loaded with and without USSCs were grafted into the skin defects. The wounds were subsequently investigated at 21 days after grafting. Results of mechanical and physical analyses showed good resilience and compliance to movement as a skin graft. In animal models; all study groups excluding the control group exhibited the most pronounced effect on wound closure, with the statistically significant improvement in wound healing being seen on post-operative Day 21. Histological and immunostaining examinations of healed wounds from all groups, especially the groups treated with stem cells, showed a thin epidermis plus recovered skin appendages in the dermal layer. Thus, the graft of collagen-coated nanofibrous PHBV scaffold loaded with USSC showed better results during the healing process of skin defects in rat model.

Keywords: collagen, nanofibrous PHBV scaffold, unrestricted somatic stem cells, wound healing.

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Authors: Gulsah Olgun, Ozgur Bozdag, Yildirim Ertutar

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This paper mainly focuses on performance assessment of buildings by associating the damage level with the damage cost. For this purpose a methodology is explained and applied to the representative mid-rise concrete building residing in Izmir. In order to consider uncertainties in occurrence of earthquakes, the structural analyses are conducted for all possible earthquakes in the region through the hazard curve. By means of the analyses, probability of the structural response being in different limit states are obtained and used to calculate expected damage cost. The expected damage cost comprises diverse cost components related to earthquake such as cost of casualties, replacement or repair cost of building etc. In this study, inter-story drift is used as an effective response variable to associate expected damage cost with different damage levels. The structural analysis methods performed to obtain inter story drifts are response spectrum method as a linear one, accurate push-over and time history methods to demonstrate the nonlinear effects on loss estimation. Comparison of the results indicates that each method provides similar values of expected damage cost. To sum up, this paper explains an approach which enables to minimize the expected damage cost of buildings and relate performance level to damage cost.

Keywords: expected damage cost, limit states, loss estimation, performance based design

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Authors: Sheimah El Bejjaji, Lara Gorsek, Chandler Quilchez, Joaquim Suñer, Mireia Mallandrich

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Flurbiprofen is an anti-inflammatory drug used in several treatments. The purpose of this study was to compare the permeation of two different formulations of flurbiprofen through the human skin. The first formulation was a solution of flurbiprofen dissolved with polyethylene glycol 3350 (PEG 3350). The second formulation was flurbiprofen encapsulated in poly-ɛ-caprolactone (PɛCL) nanoparticles (NPs), stabilized with poloxamer 188, submitted individually for freeze-drying with PEG 3350 as a cryoprotectant and sterilized by gamma-irradiation. Human skin was obtained from the abdominal region of a healthy patient. The experimental protocol was approved by the Bioethics Committee of Barcelona SCIAS Hospital (Spain), and they obtained the written informed consent forms. After being frozen to -20ºC, the skin samples were cut with a dermatome at 400 µm. The ex vivo permeation study was performed in Franz diffusion cells with a diffusion area of 2.54 cm². Skin samples were placed between two compartment sites, the dermal side in contact with the receptor medium and the epidermis side in contact with the donor chamber to which the formulation was applied. The permeation study was conducted for 24 hours at 32 ± 0.5 °C in accordance with sink conditions. The results were analyzed with an unpaired t-test, and the p-values indicate the formulation with nanoparticles had a higher permeability coefficient, flux, partition parameter, diffusion parameter, and lag time. The applicability of this formulation topically can benefit articulations and ligament inflammation as an alternative to oral drugs.

Keywords: anti-inflammatory drug, flurbiprofen, human skin, nanoparticles, skin permeation

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Authors: Ahmed M. Kabel, Maaly A. Abd Elmaaboud

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Scleroderma is one of the connective tissue disorders characterized by skin and systemic fibrosis. Its pathogenesis involves multiple interrelated processes of autoimmunity, vasculopathy, inflammation, and oxidative stress. This study was a trial to explore the possible ameliorative effects of sodium valproate on an experimental model of skin fibrosis induced by bleomycin. Forty male BALB/c mice were divided into four equal groups as follows: control group; bleomycin group; bleomycin + sodium valproate group, and sodium valproate group. Mice were assessed for their body weight every four days throughout the whole study. Skin tissues were used to evaluate the oxidative stress parameters, transforming growth factor beta 1 (TGF-β1), tumor necrosis factor alpha (TNF-α), interleukin 15, and mammalian target of rapamycin (mTOR). Skin fibrosis was evaluated by measuring dermal thickness and staining the skin tissues with Masson trichrome stain. Also, the skin tissues were immunostained with alpha smooth muscle actin (α-SMA). Administration of sodium valproate to bleomycin-treated mice resulted in the restoration of the body weight with a significant decrease in the dermal thickness, amelioration of oxidative stress, suppression of TGF-β1 and mTOR expression, and significant reduction of the percentage of α-SMA immunostaining and the proinflammatory cytokine levels compared to mice treated with bleomycin alone. In conclusion, sodium valproate has an antifibrotic effect on skin fibrosis which may represent a beneficial therapeutic modality for the management of scleroderma.

Keywords: scleroderma, bleomycin, sodium valproate, skin fibrosis

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Authors: A. Kaidal, M. M. Abdllahi, O. L. Badaki

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The study was conducted to determine the relationship between Quetelet Equation and Skin fold measurement in determining obesity among adolescent male students of University of Maiduguri Demonstration Secondary School, Borno State, Nigeria. A total of 66 students participated in the study, their age ranges from 15-18 years. The ex-post-facto research design was used for this study. Anthropometric measurements were taken at three sites (thigh, abdomen and chest) using accu–measure Skin fold caliper. The values of the three measurements were used to determine the percentage body fat of the participants using the 3-Point Skin Fold Bodyfat calculator of Jackson-Pollock. Body mass index (BMI) was determined using weight (kg) divided by height in (m2). The data obtained was analyzed using descriptive statistics (mean and standard deviation) and inferential statistics of Pearson product moment correlation coefficient to determine the relationship between the two techniques. The result showed a significant positive relationship r=0.673 p<0.05 between body mass index and skin fold measurement techniques. It was however observed that BMI techniques of determining body fat tend to overestimate the actual percent body fat of adolescents studied. Based on this result, it is recommended that the use of BMI as a technique for determining obesity should be used with caution.

Keywords: body max index, skin fold, quetelet, techniques

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Authors: Carlos Alberto Riveros, Edwin Fabián García, Javier Enrique Rivero

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The measured data obtained from sensors in continuous monitoring of civil structures are mainly used for modal identification and damage detection. Therefore when modal identification analysis is carried out the quality in the identification of the modes will highly influence the damage detection results. It is also widely recognized that the usefulness of the measured data used for modal identification and damage detection is significantly influenced by the number and locations of sensors. The objective of this study is the numerical implementation of two widely known optimum sensor placement methods in beam-like structures

Keywords: optimum sensor placement, structural damage detection, modal identification, beam-like structures.

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Authors: Malay K. Das, Bhupen Kalita

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The poor oral bioavailability of resveratrol (RSV) due to presystemic metabolism can be avoided via dermal route of administration. The hydrophilic-lipophilic nature of resveratrol-phospholipid complex (RSVPs) favors the delivery of resveratrol via the skin. The RSVPs embedded polymeric patch with moderate adhesiveness was developed for dermal application for sustained anti-inflammatory effect. The prepared patches were evaluated for various physicochemical properties, surface morphology by SEM, TEM, and compatibility of patch components by FT-IR and DSC studies. The dermal flux of the optimized patch formulation was found to be at 4.28 ± 0.48 mg/cm2/24 h. The analysis of skin extract after permeation study revealed the presence of resveratrol, which confirmed the localization of RSVPs in the skin. The stability of RSVPs in the polymeric patch and the physiologic environment was confirmed by FE-SEM studies on the patches after drug release and skin permeation studies. The RSVPs particles released from the polymer matrix maintaining the structural integrity and permeate the keratinized horney layer of skin. The optimized patch formulation showed sustained anti-inflammatory effect (84.10% inhibition of inflammation at 24 h) in carrageenan-induced rat paw edema model compared to marketed diclofenac sodium gel (39.58% inhibition of inflammation at 24 h). The CLSM study confirmed the localization of RSVPs for a longer period, thus enabling drug targeting to the dermis for sustained anti-inflammatory effect. Histological studies with phase contrast trinocular microscope suggested no alteration of skin integrity and no evidence of the presence of inflammatory cells after exposure to the permeants. The patch was found to be safe for skin application as evaluated by Draize method for skin irritation scoring in a rabbit model. These results suggest the therapeutic efficacy of the developed patch in both acute and chronic inflammatory diseases.

Keywords: resveratrol-phospholipid complex, skin delivery, sustained anti-inflammatory effect, inflammatory diseases, dermal patch

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Authors: Ahmed H. Elkholy

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Aircraft gas turbine engines are subject to damage by airborne foreign objects such as birds and garbage dumps. In order to assess their effect on engine performance, a complete foreign object damage (FOD) test was carried out and a component failure analysis was used to verify airworthiness standards (AWS) requirements for engine certification as set by international regulations. Ingestion damage due to 1.8 Kg (4 lb.) bird strike on an engine is presented in some detail. Based on the observed damage, improvements to the engine design were suggested in two different locations: the front bearing housing and the low compressor shaft. When these improvements were implemented, the engine showed an acceptable containment capability that meets AWS requirements.

Keywords: aircraft engine, airworthiness standards, bird ingestion, foreign object damage

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Authors: Akkouche Karim, Nekmouche Aghiles, Bouzid Leyla

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This study focuses on the development of a multifunctional Expert System (ES) called post-seismic damage inspection tool (PSDIT), a powerful tool which allows the evaluation, the processing and the archiving of the collected data stock after earthquakes. PSDIT can be operated by two user types; an ordinary user (engineer, expert or architect) for the damage visual inspection and an administrative user for updating the knowledge and / or for adding or removing the ordinary user. The knowledge acquisition is driven by a hierarchical knowledge model, the Information from investigation reports and those acquired through feedback from expert / engineer questionnaires are part.

Keywords: buildings, earthquake, seismic damage, damage assessment, expert system

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Authors: Buddhi Arachchige, Hessam Ghasemnejad

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In this study, the post impact behavior of curved composite plates subjected to low velocity impact was studied analytically and numerically. Approaches to damage modelling are proposed through the degradation of stiffness in the damaged region by reduction of thickness in the damage region. Spring-mass models were used to model the impact response of the plate and impactor. The study involved designing two damage models to compare and contrast the model best fitted with the numerical results. The theoretical force-time responses were compared with the numerical results obtained through a detailed study carried out in LS-DYNA. The modified damage model established a good prediction with the analytical force-time response for different layups and geometry. This study provides a gateway in selecting the most effective layups for variable stiffness curved composite panels able to withstand a higher impact damage.

Keywords: analytical modelling, composite damage, impact, variable stiffness

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Authors: Oday A. Al-Juhaishi, Sa`ad M. Ismail, Hung-Hsun Yen, Christina M. Murray, Helen M. S. Davies

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The functional anatomy of the fascia in the greyhound is still poorly understood, and incompletely described. The basic knowledge of fascia stems mainly from anatomical, histological and ultrastructural analyses. In this study, twelve specimens of hindlimbs from six fresh greyhound cadavers (3 male, 3 female) were used to examine the topographical relationships of the superficial fascia with the skin and underlying tissue. The first incision was made along the dorsal midline from the level of the thoracolumbar junction caudally to the level of the mid sacrum. The second incision was begun at the level of the first incision and extended along the midline of the lateral aspect of the hindlimb distally, to just proximal to the tarsus, and, the skin margins carefully separated to observe connective tissue links between the skin and superficial fascia, attachment points of the fascia and the relationships of the fascia with blood vessels that supply the skin. A digital camera was used to record the anatomical features as they were revealed. The dissections identified fibrous septa connecting the skin with the superficial fascia and deep fascia in specific areas. The presence of the adipose tissue was found to be very rare within the superficial fascia in these specimens. On the extensor aspects of some joints, a fusion between the superficial fascia and deep fascia was observed. This fusion created a subcutaneous bursa in the following areas: a prepatellar bursa of the stifle, a tarsal bursa caudal to the calcaneus bone, and an ischiatic bursa caudal to the ischiatic tuberosity. The evaluation of blood vessels showed that the perforating vessels passed through fibrous septa in a perpendicular direction to supply the skin, with the largest branch noted in the gluteal area. The attachment points between the superficial fascia and skin were mainly found in the region of the flexor aspect of the joints, such as caudal to the stifle joint. The numerous fibrous septa between the superficial fascia and skin that have been identified in some areas, may create support for the blood vessels that penetrate fascia and into the skin, while allowing for movement between the tissue planes. The subcutaneous bursae between the skin and the superficial fascia where it is fused with the deep fascia may be useful to decrease friction between moving areas. The adhesion points may be related to the integrity and loading of the skin. The attachment points fix the skin and appear to divide the hindlimb into anatomical compartments.

Keywords: attachment points, fibrous septa, greyhound, subcutaneous bursa, superficial fascia

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Authors: C. P. Providakis, G. M. Angeli, M. J. Favvata, N. A. Papadopoulos, C. E. Chalioris, C. G. Karayannis

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An effort for the detection of damages in the reinforcement bars of reinforced concrete members using PZTs is presented. The damage can be the result of excessive elongation of the steel bar due to steel yielding or due to local steel corrosion. In both cases the damage is simulated by considering reduced diameter of the rebar along the damaged part of its length. An integration approach based on both electromechanical admittance methodology and guided wave propagation technique is used to evaluate the artificial damage on the examined longitudinal steel bar. Two actuator PZTs and a sensor PZT are considered to be bonded on the examined steel bar. The admittance of the Sensor PZT is calculated using COMSOL 3.4a. Fast Furrier Transformation for a better evaluation of the results is employed. An effort for the quantification of the damage detection using the root mean square deviation (RMSD) between the healthy condition and damage state of the sensor PZT is attempted. The numerical value of the RSMD yields a level for the difference between the healthy and the damaged admittance computation indicating this way the presence of damage in the structure. Experimental measurements are also presented.

Keywords: concrete reinforcement, damage detection, electromechanical admittance, experimental measurements, finite element method, guided waves, PZT

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Authors: Semayat Fanta, P.M. Mohite, C.S. Upadhyay

Abstract:

Damage meso-model for laminates is one of the most widely applicable approaches for the analysis of damage induced in laminated fiber-reinforced polymeric composites. Damage meso-model for laminates has been developed over the last three decades by many researchers in experimental, theoretical, and analytical methods that have been carried out in micromechanics as well as meso-mechanics analysis approaches. It has been fundamentally developed based on the micromechanical description that aims to predict the damage initiation and evolution until the failure of structure in various loading conditions. The current damage meso-model for laminates aimed to act as a bridge between micromechanics and macro-mechanics of the laminated composite structure. This model considers two meso-constituents for the analysis of damage in ply and interface that imparted from low-velocity impact. The damages considered in this study include fiber breakage, matrix cracking, and diffused damage of the lamina, and delamination of the interface. The damage initiation and evolution in laminae can be modeled in terms of damaged strain energy density using damage parameters and the thermodynamic irreversible forces. Interface damage can be modeled with a new concept of spherical micro-void in the resin-rich zone of interface material. The damage evolution is controlled by the damage parameter (d) and the radius of micro-void (r) from the point of damage nucleation to its saturation. The constitutive martial model for meso-constituents is defined in a user material subroutine VUMAT and implemented in ABAQUS/Explicit finite element modeling tool. The model predicts the damages in the meso-constituents level very accurately and is considered the most effective technique of modeling low-velocity impact simulation for laminated composite structures.

Keywords: mesomodel, laminate, low-energy impact, micromechanics

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Authors: C. P. Providakis, G. M. Angeli, M. J. Favvata, N. A. Papadopoulos, C. E. Chalioris, C. G. Karayannis

Abstract:

An effort for the detection of damages in the reinforcement bars of reinforced concrete members using PZTs is presented. The damage can be the result of excessive elongation of the steel bar due to steel yielding or due to local steel corrosion. In both cases the damage is simulated by considering reduced diameter of the rebar along the damaged part of its length. An integration approach based on both electro-mechanical admittance methodology and guided wave propagation technique is used to evaluate the artificial damage on the examined longitudinal steel bar. Two actuator PZTs and a sensor PZT are considered to be bonded on the examined steel bar. The admittance of the Sensor PZT is calculated using COMSOL 3.4a. Fast Furrier Transformation for a better evaluation of the results is employed. An effort for the quantification of the damage detection using the root mean square deviation (RMSD) between the healthy condition and damage state of the sensor PZT is attempted. The numerical value of the RSMD yields a level for the difference between the healthy and the damaged admittance computation indicating this way the presence of damage in the structure. Experimental measurements are also presented.

Keywords: concrete reinforcement, damage detection, electromechanical admittance, experimental measurements, finite element method, guided waves, PZT

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Authors: Xianjia Meng, Chuanyong Qu

Abstract:

Compact bone produces fatigue damage under the inevitable physiological load. The accumulation of fatigue damage can change the bone’s micro-structure at different scales and cause the catastrophic failure eventually. However, most tests were limited to the macroscopic modulus of bone and there is a need to assess the microscopic modulus during fatigue progress. In this paper, nano-identation was used to investigate the bone specimen subjected to four point bending. The microscopic modulus of the same area were measured at different degrees of damage including fracture. So microscopic damage can be divided into three stages: first, the modulus decreased rapidly and then They fell slowly, before fracture the decline became fast again. After fracture, the average modulus decreased by 20%. The results of inner and outer planes explained the influence of compressive and tensile loads on modulus. Both the compressive and tensile moduli decreased with the accumulation of damage. They reached the minimum at ending and increased after fracture. The modulus evolution under different strains were revealed by the side. They all fell slowly and then fast with the accumulation of damage. The fractured results indicated that the elastic modulus decreased obviously at the high strain while decreased less at the low strain. During the fatigue progress, there was a significant difference in modulus at low degree of damage. However, the dispersed modulus tended to be similar at high degree of damage, but they became different again after the failure.

Keywords: fatigue damage, fracture, microscopic modulus, bone, nano-identation

Procedia PDF Downloads 166

Authors: Yen-Po Wang, Ming-Chih Huang, Ming-Lian Chang

Abstract:

A scheme integrated with deterministic–stochastic subspace system identification and the method of damage localization vector is proposed in this study for damage detection of structures based on seismic response data. A series of shaking table tests using a five-storey steel frame has been conducted in National Center for Research on Earthquake Engineering (NCREE), Taiwan. Damage condition is simulated by reducing the cross-sectional area of some of the columns at the bottom. Both single and combinations of multiple damage conditions at various locations have been considered. In the system identification analysis, either full or partial observation conditions have been taken into account. It has been shown that the damaged stories can be identified from global responses of the structure to earthquakes if sufficiently observed. In addition to detecting damage(s) with respect to the intact structure, identification of new or extended damages of the as-damaged (ill-conditioned) counterpart has also been studied. The proposed scheme proves to be effective.

Keywords: damage locating vectors, deterministic-stochastic subspace system, shaking table tests, system identification

Procedia PDF Downloads 328

Authors: G .D. B. N. Kulasaooriya, H. B. S. Ariyarathne, I. Abeygunawardene, A. A. J. Rafarathne, B. V. Perera

Abstract:

Elephant is the largest resident of the wild and has small surface to volume ratio as well as less number of sweat glands which cause challenges to the thermoregulation of this mammal. However, this megaherbivore has adopted specialised meachanisms to maintain its thermal balance through behavioral adaptations, ear flapping and well anastomosed arterioles and venules of the ear. Nevertheless, little is known on the involvement of the skin in the process of thermoregulation. The present study was undertaken to monitor the water evaporation rate from the skin of unrestrained wild elephant calves throughout the day and to understand its importance in the thermoregulation. Seven baby elephants housed in the elephant transit home, Udawalawe were used. Ambient temparature, relative humidity (RH) and radiation heat load was monitored throughout the day of the study period. Similarly, surface temparature of the skin was taken at six points including lateral ear pinna, lateral body and the rump during the same period. The skin water evaporation was also measured from the same sites using cobolt chloride method. The surface are of the skin was determined by assigning geometrical shapes to each body part. The results showed that the ambient temperature gradually increased with the day reaching maximum around 3.00 pm. The relative humidity was lowest early in the morning. The radiation heat load did not show any significant change in the study period. The skin temperature was different among lateral ear pinna, lateral body and the rump where the highest temperature was on the rump and the lowest on the lateral ear pinna. The skin temperature gradually increase with increasing ambient temperature but there was not a strong correlation (R2 =53.53) between these two. The skin temperature had strong correlation with RH (p<0.05 R2 =70.84% ) but a significant relationship was not considered since the radiation heat load was not varying in large scale. The skin evaporative water loss had a weak negative correlation with ambient temperature (correlation coefficient= -0.01) whereas strong positive correlation with RH (correlation coefficient= 25.275 ) and no corelation with radiation heat load. It also appeared that skin water loss increases as the skin temperature increased. In the present study, it was observed that on average, skin of the baby elephant looses 403 g/m2/h of water. Based on these observations it can be concluded that a large volume of water is evaporated from the skin of baby elephants and evaporative heat loss may be contributing significantly to the thermoregulation. However, further investigation on the influence of environmental factors on evaporative heat loss has to be conducted to understand the thermoregulatory mechanisms of the baby elephant.

Keywords: thermoregulation, behavioral adaptations, evaporation, elephant

Procedia PDF Downloads 379