scholarly journals DESIGN OF SPECIALIZED SURGICAL SCREW INSERTED IN PLATE TYPE CERVICAL IMPLANT

2021 ◽  
Vol 2 ◽  
pp. 10-14
Author(s):  
Krasimira Dimova ◽  
Georgi Todorov ◽  
Yavor Sofronov
Keyword(s):  
Bone Tissue ◽  
Complex Geometry ◽  
Fem Analysis ◽  
Main Function ◽  
Tissue Properties ◽  
Virtual Tools ◽  
Injured Area ◽  
Different Types ◽  
Materials Used ◽  
Plate Type

In the field of Implantology the screws are an important part because they transfer the loads that occur in the bones. Surgical screws are similar to those in Mechanical Engineering, but the materials should have specific characteristics like biocompatibility, strength, corrosion resistance and fatigue strength. The main function of the surgical screw is to create pressure between two bones which is necessary in order to heal the injured bones. The surgical screw transforms all forces of the movements to pressure and distributes the pressure on the bone’s surfaces. Surgical screws can help in the setting of implants into an injured area. It also ensures static position of the injured bones. The research aims to analyse how the surgical screw type affects the bone of the patient with the help of the Finite Elements Method (FEM). Based on the results from the analysis of the surgical screw a new specialized surgical screw was designed with complex geometry to withstand the occurring loads and also be able to transfer them to the bone tissue. In additional, a comparison analysis between two different types of surgical screws was conducted. This paper shows how a surgical screw could be optimized in order to improve its function with the help of virtual tools. Finally, the materials used are biocompatible and often used for such screws and surgical implant analysis, the challenge was to recreate the bone tissue properties and to used them in the FEM analysis.

The Type of Roofs in Environmental Conditions with Different Shape and Suggested Suitable Materials

2013 ◽  
Vol 685 ◽  
pp. 245-249 ◽  
Author(s):  
Golzar Younesi ◽  
Sahereh Mehrabian ◽  
Farzan Rasoulzadeh
Keyword(s):  
Environmental Conditions ◽  
Human Life ◽  
Quality Characteristics ◽  
Climatic Conditions ◽  
Rain Water ◽  
Main Function ◽  
The Sun ◽  
Current Technology ◽  
Different Types ◽  
Materials Used

Roofs from the fifth skin of buildings and define the character of the architecture. Their main function is sometimes to provide protection against the sun and wind, and sometimes to channel, collect and store rain water. Each climate required a different type of roof to its specific need protection of human life. The choice of one type of roof another depends fundamentally on the client brief, on the implications of the environment, on the climatic conditions and on the resources available or current technology. For a roof with certain quality characteristics there may be different technological and budgetary solutions. The roof must be conceived constructively, rationalized and adapted to the variable conditions of its environment. In this paper, we review the different types of roof, the materials used and their auxiliary elements.

HYDROXYAPATITE, ALGINATE, AND CHITOSAN FOR BONE SCAFFOLDS: SPECTROSCOPY STUDY

2016 ◽  
Vol 19 (2) ◽  
pp. 93-100
Author(s):  
Lalita El Milla
Keyword(s):  
Tissue Engineering ◽  
Bone Tissue Engineering ◽  
Bone Tissue ◽  
Functional Groups ◽  
Bone Growth ◽  
Three Dimensional ◽  
Dimensional Structure ◽  
Tissue Engineering Scaffolds ◽  
Hydroxyapatite Powder ◽  
Materials Used

Scaffolds is three dimensional structure that serves as a framework for bone growth. Natural materials are often used in synthesis of bone tissue engineering scaffolds with respect to compliance with the content of the human body. Among the materials used to make scafffold was hydroxyapatite, alginate and chitosan. Hydroxyapatite powder obtained by mixing phosphoric acid and calcium hydroxide, alginate powders extracted from brown algae and chitosan powder acetylated from crab. The purpose of this study was to examine the functional groups of hydroxyapatite, alginate and chitosan. The method used in this study was laboratory experimental using Fourier Transform Infrared (FTIR) spectroscopy for hydroxyapatite, alginate and chitosan powders. The results indicated the presence of functional groups PO43-, O-H and CO32- in hydroxyapatite. In alginate there were O-H, C=O, COOH and C-O-C functional groups, whereas in chitosan there were O-H, N-H, C=O, C-N, and C-O-C. It was concluded that the third material containing functional groups as found in humans that correspond to the scaffolds material in bone tissue engineering.

scholarly journals Biopolymeric Materials Used as Nonviral Vectors: A Review

2021 ◽  
Vol 2 (1) ◽  
pp. 100-109
Author(s):  
Jailson de Araújo Santos ◽  
Daniel Barbosa Liarte ◽  
Alessandra Braga Ribeiro ◽  
Marcia dos Santos Rizzo ◽  
Marcília Pinheiro da Costa ◽  
...  
Keyword(s):  
Chemical Structure ◽  
Web Of Science ◽  
Gene Transfection ◽  
Genetic Material ◽  
Nonviral Vectors ◽  
Cationic Polymers ◽  
Genetic Trait ◽  
Low Diversity ◽  
Different Types ◽  
Materials Used

Bacterial transformation and gene transfection can be understood as being the results of introducing specific genetic material into cells, resulting in gene expression, and adding a new genetic trait to the host cell. Many studies have been carried out to investigate different types of lipids and cationic polymers as promising nonviral vectors for DNA transfer. The present study aimed to carry out a systematic review on the use of biopolymeric materials as nonviral vectors. The methodology was carried out based on searches of scientific articles and applications for patents published or deposited from 2006 to 2020 in different databases for patents (EPO, USPTO, and INPI) and articles (Scopus, Web of Science, and Scielo). The results showed that there are some deposits of patents regarding the use of chitosan as a gene carrier. The 16 analyzed articles allowed us to infer that the use of biopolymers as nonviral vectors is limited due to the low diversity of biopolymers used for these purposes. It was also observed that the use of different materials as nonviral vectors is based on chemical structure modifications of the material, mainly by the addition of cationic groups. Thus, the use of biopolymers as nonviral vectors is still limited to only a few polysaccharide types, emphasizing the need for further studies involving the use of different biopolymers in processes of gene transfer.

Effect of Bone Tumor and Osteoporosis on Mechanical Properties of Bone and Bone Tissue Properties: A Finite Element Study

2007 ◽  
Author(s):  
Vipul P. Gohil ◽  
Paul K. Canavan ◽  
Hamid Nayeb-Hashemi
Keyword(s):  
Mechanical Properties ◽  
Finite Element ◽  
Bone Density ◽  
Bone Tissue ◽  
Bone Tumor ◽  
Cellular Structure ◽  
Bone Tumors ◽  
World Health ◽  
Tissue Stiffness ◽  
Tissue Properties

This research is aimed to study the variations in the biomechanical behavior of bone and bone tissues with osteoporosis and bone tumors. Osteoporosis and bone tumors reduce the mechanical strength of bone, which creates a greater risk of fracture. In the United States alone, ten million individuals, eight million of whom are women, are estimated to already have osteoporosis, and almost 34 million more are estimated to have low bone mass (osteopenia) placing them at increased risk for osteoporosis. World Health Organization defines osteopenia, as a bone density between one and two and a half standard deviations (SD) below the bone density of a normal young adult. (Osteoporosis is defined as 2.5 SD or more below that reference point.). Together, osteoporosis and osteopenia are expected to affect an estimated 52 million women and men age 50 and older by 2010, and 61 million by 2020. The current medical cost of osteoporosis total is nearly about $18 billion in the U.S. each year. There is a dearth of literature that addresses the effects of osteoporosis on bone tissue properties. Furthermore, there are few studies published related to the effect of bone tumors such as Adamantinoma of long bones, Aneurysmal bone cyst, Hemangioma and others on overall behavior of bone. To understand the variations in bio-mechanical properties of internal tissues of bone with osteoporosis and bone tumor, a 2D finite element (FE) model of bone is developed using ANSYS 9.0 ® (ANSYS Inc., Canonsburg, PA). Trabecular bone is modeled using hexagonal and voronoi cellular structure. This finite element model is subjected to change in BVF (bone volume fraction) and bone architecture caused by osteoporosis. The bone tumor is modeled as finer multi-cellular structure and the effects of its size, location, and property variation of tumor on overall bone behavior are studied. Results from this analysis and comparative data are used to determine behavior of bone and its tissue over different stage of osteoporosis and bone tumor. Results indicate that both bone tumor and osteoporosis significantly change the mechanical properties of the bone. The results show that osteoporosis increases the bone tissue stiffness significantly as BVF reduces. Bone tissue stiffness is found to increase by 80 percent with nearly 55 percent reduction of BVF. The results and methods developed in this research can be implemented to monitor variation in bio-mechanical properties of bone up to tissue level during medication or to determine type and time for need of external support such as bracing.

scholarly journals FEM Analysis of Various Multilayer Structures for CMOS Compatible Wearable Acousto-Optic Devices

Sensors ◽  
2021 ◽  
Vol 21 (23) ◽  
pp. 7863
Author(s):  
Mehwish Hanif ◽  
Varun Jeoti ◽  
Mohamad Radzi Ahmad ◽  
Muhammad Zubair Aslam ◽  
Saima Qureshi ◽  
...  
Keyword(s):  
Coupling Coefficient ◽  
Figure Of Merit ◽  
Electromechanical Coupling ◽  
Piezoelectric Materials ◽  
Fem Analysis ◽  
Film Structure ◽  
Multilayer Structures ◽  
Electromechanical Coupling Coefficient ◽  
Materials Used ◽  
The Individual

Lately, wearable applications featuring photonic on-chip sensors are on the rise. Among many ways of controlling and/or modulating, the acousto-optic technique is seen to be a popular technique. This paper undertakes the study of different multilayer structures that can be fabricated for realizing an acousto-optic device, the objective being to obtain a high acousto-optic figure of merit (AOFM). By varying the thicknesses of the layers of these materials, several properties are discussed. The study shows that the multilayer thin film structure-based devices can give a high value of electromechanical coupling coefficient (k2) and a high AOFM as compared to the bulk piezoelectric/optical materials. The study is conducted to find the optimal normalised thickness of the multilayer structures with a material possessing the best optical and piezoelectric properties for fabricating acousto-optic devices. Based on simulations and studies of SAW propagation characteristics such as the electromechanical coupling coefficient (k2) and phase velocity (v), the acousto-optic figure of merit is calculated. The maximum value of the acousto-optic figure of merit achieved is higher than the AOFM of all the individual materials used in these layer structures. The suggested SAW device has potential application in wearable and small footprint acousto-optic devices and gives better results than those made with bulk piezoelectric materials.

Comparative Study of Ceramics Structure for Culturing Human Mesenchymal Stromal Cells

2007 ◽  
Vol 361-363 ◽  
pp. 1067-1070 ◽  
Author(s):  
Asako Matsushima ◽  
Noriko Kotobuki ◽  
Mika Tadokoro ◽  
Hajime Ohgushi
Keyword(s):  
Bone Tissue ◽  
Mesenchymal Stromal Cells ◽  
Stromal Cells ◽  
Cell Attachment ◽  
Osteoblastic Differentiation ◽  
Human Mscs ◽  
Osteogenic Cells ◽  
Human Mesenchymal Stromal Cells ◽  
Viable Cells ◽  
Different Types

Hydroxyapatite (HA) ceramics together with various kinds of osteogenic cells have been used in bone tissue engineering. It is well known that the ceramics structure and composition affect cell proliferation / differentiation. In this study, three different types of HA ceramics were used to investigate initial cell attachment followed by osteoblastic differentiation of human mesenchymal stromal cells (MSCs). The results indicated that micro-pore affected the cell attachment and porosity (pore diameter and inter-pore connection) was the key to allow spacious distribution of the viable cells in the ceramics. This study also confirmed that surface pore areas of HA ceramics support the differentiation of human MSCs and thus the ceramics have the capability to regenerate damaged bone tissue.

Location Depending Textures of the Human Dental Enamel

2010 ◽  
Vol 160 ◽  
pp. 281-286 ◽  
Author(s):  
Lars Raue ◽  
Helmut Klein
Keyword(s):  
Mechanical Properties ◽  
Lactic Acid ◽  
Dental Enamel ◽  
Polymeric Materials ◽  
Incisor Tooth ◽  
Worst Case ◽  
Dental Fillings ◽  
Anisotropic Mechanical Properties ◽  
Different Types ◽  
Materials Used

Dental enamel is the most highly mineralised and hardest biological tissue in human body [1]. Dental enamel is made of hydroxylapatite (HAP) - Ca5(PO4)3(OH), which is hexagonal (6/m). The lattice parameters are a = b = 0.9418 nm und c = 0.6875 nm [1]. Although HAP is a very hard mineral, it can be dissolved easily in a process which is known as enamel demineralization by lactic acid produced by bacteria. Also the direct consumption of acid (e.g. citric, lactic or phosphoric acid in soft drinks) can harm the dental enamel in a similar way. These processes can damage the dental enamel. It will be dissolved completely and a cavity occurs. The cavity must then be cleaned and filled. It exists a lot of dental fillings, like gold, amalgam, ceramics or polymeric materials. After filling other dangers can occur: The mechanical properties of the materials used to fill cavities can differ strongly from the ones of the dental enamel itself. In the worst case, the filling of a tooth can damage the enamel of the opposite tooth by chewing if the interaction of enamel and filling is not equivalent, so that the harder fillings can abrade the softer enamel of the healthy tooth at the opposite side. This could be avoided if the anisotropic mechanical properties of dental enamel would be known in detail, hence then another filling could be searched or fabricated as an equivalent opponent for the dental enamel with equal properties. To find such a material, one has to characterise the properties of dental enamel first in detail for the different types of teeth (incisor, canine, premolar and molar). This is here exemplary done for a human incisor tooth by texture analysis with the program MAUD from 2D synchrotron transmission images [2,3,4].

Effect for Micro-Transformer Using Different Substrate Materials

2011 ◽  
Vol 135-136 ◽  
pp. 484-486
Author(s):  
Xiao Wei Hou ◽  
Shi Bin Liu ◽  
Jie Chang
Keyword(s):  
Thin Film ◽  
Substrate Material ◽  
Main Function ◽  
Voltage Gain ◽  
Thin Film Fabrication ◽  
Surface Configuration ◽  
Parasitic Effect ◽  
Film Fabrication ◽  
Materials Used ◽  
Quartz Ceramics

The main function of the substrate is to sustain and improve the performance of the thin-film. The property and surface configuration of the substrate material have a huge influence on the characteristics of the thin-film. Fabrication of substrate for the micro-transformer can choose a variety of materials, including the silicon, metal, glass, quartz, ceramics, plastics, polymer, etc. Different materials used as substrate have different effects on voltage gain and insertion loss of the transformer. At present, the silicon is used in most cases for its excellent properties. However, it is increasingly found that there exists some problems to gain better performance, such as the parasitic effect. And so, to employ other materials is essential. This paper discusses the effects induced by using different substrate materials. Through the analysis, a general cognition about how to choose the materials can be obtained, which is helpful to design and fabrication of the micro-transformer.

scholarly journals Nano-Structured Optical Fibers Made of Glass-Ceramics, and Phase Separated and Metallic Particle-Containing Glasses

Fibers ◽  
2019 ◽  
Vol 7 (12) ◽  
pp. 105 ◽  
Author(s):  
Alexander Veber ◽  
Zhuorui Lu ◽  
Manuel Vermillac ◽  
Franck Pigeonneau ◽  
Wilfried Blanc ◽  
...  
Keyword(s):  
Fiber Optics ◽  
Optical Fibers ◽  
Metallic Nanoparticles ◽  
Glass Ceramics ◽  
Optical Quality ◽  
High Optical Quality ◽  
Characterization Methods ◽  
Different Types ◽  
Fabrication And Characterization ◽  
Materials Used

For years, scientists have been looking for different techniques to make glasses perfect: fully amorphous and ideally homogeneous. Meanwhile, recent advances in the development of particle-containing glasses (PCG), defined in this paper as glass-ceramics, glasses doped with metallic nanoparticles, and phase-separated glasses show that these “imperfect” glasses can result in better optical materials if particles of desired chemistry, size, and shape are present in the glass. It has been shown that PCGs can be used for the fabrication of nanostructured fibers—a novel class of media for fiber optics. These unique optical fibers are able to outperform their traditional glass counterparts in terms of available emission spectral range, quantum efficiency, non-linear properties, fabricated sensors sensitivity, and other parameters. Being rather special, nanostructured fibers require new, unconventional solutions on the materials used, fabrication, and characterization techniques, limiting the use of these novel materials. This work overviews practical aspects and progress in the fabrication and characterization methods of the particle-containing glasses with particular attention to nanostructured fibers made of these materials. A review of the recent achievements shows that current technologies allow producing high-optical quality PCG-fibers of different types, and the unique optical properties of these nanostructured fibers make them prospective for applications in lasers, optical communications, medicine, lighting, and other areas of science and industry.

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