Search results for: denture adhesive

Authors: Sajjad Esmaeili, Robert Krause, Lukas Gerlich, Alireza Mohammadian Kia, Benjamin Uhlig

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This investigation aims to develop the feasible and qualitative process parameters for the thin films fabrication into ultra-large through-silicon-vias (TSVs) as vertical interconnections. The focus of the study is on TSV metallization and its challenges employing new materials for the purpose of rapid signal propagation in the microsystems technology. Cobalt metal-organic chemical vapor deposition (Co-MOCVD) process enables manufacturing an adhesive and excellent conformal ultra-thin film all the way through TSVs in comparison with the conventional non-conformal physical vapor deposition (PVD) process of copper (Cu) seed layer. Therefore, this process provides a Cu seed-free layer which is capable of direct Cu electrochemical deposition (Cu-ECD) on top of it. The main challenge of this metallization module is to achieve the proper alternative seed layer with less roughness, sheet resistance and granular organic contamination (e.g. carbon) which intensify the Co corrosion under the influence of Cu electrolyte.

Keywords: Cobalt MOCVD, direct Cu electrochemical deposition (ECD), metallization technology, through-silicon-via (TSV)

Procedia PDF Downloads 126

Authors: Štěpán Hýsek, Milan Podlena, Miloš Pavelek, Matěj Hodoušek, Martin Böhm, Petra Gajdačová

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Particle boards have being used in the civil engineering as a decking for load bearing and non-load bearing vertical walls and horizontal panels (e. g. floors, ceiling, roofs) in a large scale. When the straw is used as non-wood material for manufacturing of lignocellulosic panels, problems with wax layer on the surface of the material can occur. Higher percentage of silica and wax cause the problems with the adhesion of the adhesive and this is the reason why it is necessary to break the surface layer for the better bonding effect. Surface treatment of the particles cause better mechanical properties, physical properties and the overall better results of the composite material are reached. Plasma application is one possibility how to modify the surface layer. The aim of this research is to modify the surface of straw particles by using cold plasma treatment. Surface properties of lignocellulosic materials were observed before and after cold plasma treatment. Cold plasma does not cause any structural changes deeply in the material. There are only changes in surface layers, which are required. Results proved that the plasma application influenced the properties of surface layers and the properties of composite material.

Keywords: composite, lignocellulosic materials, straw, cold plasma, surface treatment

Procedia PDF Downloads 302

Authors: S. A. Abdellatef, A. Taniguchi, Namiki, Tsukuba, Ibaraki

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The alterations in the physicochemical characteristics of bio-materials are renowned for their impact in cellular behaviors. Surface chemistry and substratum topography are separately considered as mutable characteristics with deep impact on the overall cell behaviors. In our recent work, we examined the manipulation of the physical cues on hepatic cellular behaviors. We have proven that the geometrical or dimensional characteristics of nano features are essential for the optimum hepatocellular functions. While here, the collective impact of both physical and chemical cues on hepatocellular behaviors was investigated. On which RGD peptide was immobilized on a TiO2 nano pattern that imitates the hierarchically extend collagen nano fibrillar structures. The hepatocytes morphological and functional changes induced by simultaneously combining the diversified cues were investigated. TiO2 substrates that integrate nano topography with the adhesive peptide motif (RGD) had showed an increase in the hepatocellular functionality to the maximum extent. While a significant enhancement in expression of these liver specific markers on RGD coated surfaces were observed compared to uncoated substrates regardless of topography. Consequently in depth understanding of the relationship between various kind of cues and hepatocytes behaviors would be a paving step in the application of tissue engineering and bio reactor technology.

Keywords: biomaterial, tiO2, hepG2, RGD

Procedia PDF Downloads 367

Authors: B. Nečasová, P. Liška, J. Šlanhof

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Verification of vented wooden façade system with bonded joints is presented in this paper. The potential of bonded joints is studied and described in more detail. The paper presents the results of an experimental and theoretical research about the effects of freeze cycling on the bonded joint. For the purpose of tests spruce timber profiles were chosen for the load bearing substructure. Planks from wooden plastic composite and Siberian larch are representing facade cladding. Two types of industrial polyurethane adhesives intended for structural bonding were selected. The article is focused on the preparation as well as on the subsequent curing and conditioning of test samples. All test samples were subjected to 15 cycles that represents sudden temperature changes, i.e. immersion in a water bath at (293.15 ± 3) K for 6 hours and subsequent freezing to (253.15 ± 2) K for 18 hours. Furthermore, the retention of bond strength between substructure and cladding was tested and strength in shear was determined under tensile stress. Research data indicate that little, if any, damage to the bond results from freezing cycles. Additionally, the suitability of selected group of adhesives in combination with timber substructure was confirmed.

Keywords: adhesive system, bonded joints, wooden lightweight façade, timber substructure

Procedia PDF Downloads 367

Authors: Redha Yeghnem, Laid Boulefrakh, Sid Ahmed Meftah, Abdelouahed Tounsi, El Abbas Adda Bedia

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In this study, the time-dependent behavior of damaged reinforced concrete shear wall structures strengthened with composite plates having variable fibers spacing was investigated to analyze their seismic response. In the analytical formulation, the adherent and the adhesive layers are all modeled as shear walls, using the mixed finite element method (FEM). The anisotropic damage model is adopted to describe the damage extent of the RC shear walls. The phenomenon of creep and shrinkage of concrete has been determined by Eurocode 2. Large earthquakes recorded in Algeria (El-Asnam and Boumerdes) have been tested to demonstrate the accuracy of the proposed method. Numerical results are obtained for non uniform distributions of carbon fibers in epoxy matrices. The effects of damage extent and the delay mechanism creep and shrinkage of concrete are highlighted. Prospects are being studied.

Keywords: RC shear wall structures, composite plates, creep and shrinkage, damaged reinforced concrete structures, finite element method

Procedia PDF Downloads 334

Authors: Noushin Shokouhinejad, Hasan Razmi, Reza Fekrazad, Saeed Asgary, Ammar Neshati, Hadi Assadian, Sanam Kheirieh

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This study compared the push-out bond strength of mineral trioxide aggregate (MTA) and a new endodontic cement (NEC) as root-end filling materials in root-end cavities prepared by ultrasonic technique (US) or Er,Cr:YSGG laser (L). Eighty single-rooted extracted human teeth were endodontically treated, apicectomised and randomly divided into four following groups (n = 20): US/MTA, US/NEC, L/MTA and L/NEC. In US/MTA and US/NEC groups, rooted cavities were prepared with ultrasonic retrotip and filled with MTA and NEC, respectively. In L/MTA and L/NEC groups, root-end cavities were prepared using Er, Cr:YSGG laser and filled with MTA and NEC, respectively. Each root was cut apically to create a 2 mm-thick root slice for measurement of bond strength using a universal testing machine. Then, all slices were examined to determine the mode of bond failure. Data were analysed using two-way ANOVA. Root-end filling materials showed significantly higher bond strength in root-end cavities prepared using the ultrasonic technique (US/MTA and US/NEC) (P < 0.001). The bond strengths of MTA and NEC did not differ significantly. The failure modes were mainly adhesive for MTA, but cohesive for NEC. In conclusion, bond strengths of MTA and NEC to root-end cavities were comparable and higher in ultrasonically prepared cavities.

Keywords: bond strength, Er, Cr:YSGG laser, MTA, NEC, root-end cavity

Procedia PDF Downloads 309

Authors: Maizatulnisa Othman, Mohamad Bukhari, Zahurin Halim, Souad A. Muhammad, Khalisani Khalid

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Sandwich structure composites produced by epoxy core and aluminium skin were developed as potential building materials. Interface bonding between core and skin was controlled by varying kenaf content. Five different weight percentage of kenaf loading ranging from 10 wt% to 50 wt% were employed in the core manufacturing in order to study the mechanical properties of the sandwich composite. Properties of skin aluminium with epoxy were found to be affected by drying time of the adhesive. Mechanical behavior of manufactured sandwich composites in relation with properties of constituent materials was studied. It was found that 30 wt% of kenaf loading contributed to increase the flexural strength and flexural modulus up to 102 MPa and 32 Gpa, respectively. Analysis were done on the flatwise and edgewise compression test. For flatwise test, it was found that 30 wt% of fiber loading could withstand maximum force until 250 kN, with compressive strength results at 96.94 MPa. However, at edgewise compression test, the sandwich composite with same fiber loading only can withstand 31 kN of the maximum load with 62 MPa of compressive strength results.

Keywords: sandwich structure composite, epoxy, aluminium, kenaf fiber

Procedia PDF Downloads 361

Authors: Hamza Javar Magnier, Leslie V. Woodcock

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It has been reported that at temperatures above the critical there is no “continuity of liquid and gas”, as originally hypothesized by van der Waals. Rather, both gas and liquid phases, with characteristic properties as such, extend to supercritical temperatures. Each phase is bounded by the locus of a percolation transition, i.e. a higher-order thermodynamic phase change associated with percolation of gas clusters in a large void, or liquid interstitial vacancies in a large cluster. Between these two-phase bounds, it is reported there exists a mesophase that resembles an otherwise homogeneous dispersion of gas micro-bubbles in liquid (foam) and a dispersion of liquid micro-droplets in gas (mist). Such a colloidal-like state of a pure one-component fluid represents a hitherto unchartered equilibrium state of matter besides pure solid, liquid or gas. Here we provide compelling evidence, from molecular dynamics (MD) simulations, for the existence of this supercritical mesophase and its colloidal nature. We report preliminary results of computer simulations for a model fluid using a simplistic representation of atoms or molecules, i.e. a hard-core repulsion with an attraction so short that the atoms are referred to as “adhesive spheres”. Molecular clusters, and hence percolation transitions, are unambiguously defined. Graphics of color-coded clusters show colloidal characteristics of the supercritical mesophase.

Keywords: critical phenomena, mesophase, supercritical, square-well, critical parameters

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Authors: Ulli Heinlein, Thomas Freimann

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Pre-applied bonded membranes are used as positive-side waterproofing on concrete basements, are installed before the concrete work, and achieve a tear-resistant and waterproof bond with the subsequently placed fresh concrete. This bond increases redundancy compared to lose waterproofing membranes by preventing lateral water migrations in the event of damage. So far, the membranes have been tested in the laboratory, but it is not yet known how they behave on construction sites in the presence of dirt, soil, cement paste or moisture. This article, therefore, conducts investigations on six construction sites using 18 test slabs where the pre-applied bonded membranes are selectively contaminated or wetted. Subsequently, cores are taken, and the influence of the contaminations on the adhesive tensile strength and waterproof bond is tested. Pre-applied bonded membranes with smooth or granular but closed surfaces show no sensitivity to wetness, whereas open-pored membranes with nonwovens do not tolerate standing water. Contaminations decline the performance of all pre-applied bonded membranes since a separating layer is formed between the bonding layer and the concrete. The influence depends on the thickness of the contamination and its mechanical properties.

Keywords: waterproofing, positive-side waterproofing, basement, pre-applied bonded waterproofing membrane, In-situ testing, lateral water migrations

Procedia PDF Downloads 159

Authors: Adama NS Bah

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Background: Loss of teeth has a negative influence on essential oral functions such as phonetics, mastication, and aesthetics. Dentists treat people with prosthodontic rehabilitation to recover essential oral functions. The oral health quality of life inventory reflects the success of prosthodontic rehabilitation. In many countries, the current conventional care delivered to replace missing teeth for adult patients involves the provision of removable partial dentures. Aim: The aim of this systematic review and meta-analysis is to gather the best available evidence to determine patients’ oral health-related quality of life improvement after treatment with partial dentures. Methods: We searched electronic databases from January 2010 to September 2019, including PubMed, ProQuest, Science Direct, Scopus and Google Scholar. In this paper, studies were included only if the average age was 30 years and above and also published in English. Two reviewers independently screened and selected all the references based on inclusion criteria using the PRISMA guideline, and assessed the quality of the included references using the Joanna Briggs Institute quality assessment tools. Data extracted were analyzed in RevMan 5.0 software, the heterogeneity between the studies was assessed using Forest plot, I2 statistics and chi-square test with a statistical P value less than 0.05 to indicate statistical significance. Random effect models were used in case of moderate or high heterogeneity. Four studies were included in the systematic review and three studies were pooled for meta-analysis. Results: Four studies included in the systematic review and three studies included in the meta-analysis with a total of 285 patients comparing the improvement in oral health-related quality of life before and after rehabilitation with partial denture, the pooled results showed a better improvement of oral health-related quality of life after treatment with partial dentures (mean difference 5.25; 95% CI [3.81, 6.68], p < 0.00001) favoring the wearing of partial dentures. In order to ascertain the reliability of the included studies for meta-analysis risk of bias was assessed and found to be low in all included studies for meta-analysis using the Cochrane collaboration tool for risk of bias assessment. Conclusion: There is high evidence that rehabilitation with partial dentures can improve the patient’s oral health-related quality of life measured with Oral Health Impact Profile 14. This review has clinical evidence value for dentists treating the expanding vulnerable adult population.

Keywords: meta-analysis, oral health impact profile, partial dentures, systematic review

Procedia PDF Downloads 81

Authors: Bharat Kumar, Deepak Kumar, Vijay Chaudhry

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Zirconium alloys exhibit low neutron absorption cross-section and excellent mechanical properties. Due to these unique characteristics, these materials are widely used in designing core components of pressurized heavy water reactors (PHWRs). Another material that is widely used in the design of reactor core is stainless steel. Under operating conditions of the reactor, there are possibilities for mechanical and tribological interaction between the components made of zirconium alloy (Zr-2.5 Nb) and stainless steel (SS-410). This may result in wear of the material. To study the tribological characteristics of Zr-2.5 Nb and SS-410, low amplitude reciprocating wear tests are conducted at room temperature and at high temperatures (260 degrees Celsius). The tests are conducted at frequencies ranging from 5 Hz to 25 Hz. The displacement amplitude is varied from 200 µm to 600 µm. The responses are recorded, analyzed and correlated with damage observed using scanning electron microscopy (SEM) and an optical profilometer. Energy dispersive spectroscopy (EDS) is used to study the damage mechanism prevailing at the contact interface. A higher coefficient of friction (COF) is observed at higher temperatures as compared to the one at room temperature. Tests carried out at high temperature reveals adhesive wear as the dominant mechanism resulting in significant material transfer.

Keywords: PHWRs, Zr-2.5Nb, SS-410, wear

Procedia PDF Downloads 57

Authors: Olena Grygorieva

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Nowadays mechanisms of thymocytes emigration from the thymus to the periphery are investigated actively. We have proposed a hypothesis of thymocytes’ migration from the thymus through lymphatic vessels during periodical short-term local edema. By morphological, hystochemical methods we have examined quantity of lymphocytes, epitelioreticulocytes, mast cells, blood and lymphatic vessels in morpho-functional areas of rats’ thymuses during the first week after birth in 4 hours interval. In newborn and beginning from 8 hour after birth every 12 hours specific density of the thymus, absolute quantity of microcirculatory vessels, especially of lymphatic ones, lymphcyte-epithelial index, quantity of mast cells and their degranulative forms increase. Structure of extracellular matrix, intrathymical microenvironment and lymphocytes’ adhesive properties change. Absolute quantity of small lymphocytes in thymic cortex changes wavy. All these changes are straightly expressed from 0 till 2, from 12 till 16, from 108 till 120 hours of postnatal life. During this periods paravasal lymphatic vessels are stuffed with lymphocytes, i.e. discrete migration of lymphocytes from the thymus occurs. After rapid edema reduction, quantity of lymphatic vessels decrease, they become empty. Therefore, in the thymus of newborn periodical short-term local edema is observed, on its top discrete migration of lymphocytes from the thymus occurs.

Keywords: lymphocytes, lymphatic vessels, mast cells, thymus

Procedia PDF Downloads 199

Authors: Qian Qiao, Tongjin Xiao, Hongtu He, Jiaxin Yu

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This study is focused on the synergetic effects of water and sulfur dioxide treatments (SO₂ treatments) on the mechanochemical wear of SLS glass. It is found that the wear behavior of SLS glass in humid air is very sensitive to the water and SO₂ treatment environments based on the wear test using a ball-on-flat reciprocation tribometer. When SLS glass is treated with SO₂-without, the presence of water, the wear resistance of SLS glass in humid air becomes significantly higher compared to the pristine glass. However, when SLS glass is treated with SO₂ with the presence of water, the wear resistance of SLS glass decreases remarkably with increasing in the relative humidity (RH) from 0% to 90%. Further analyses indicate that when sodium ions are leached out of SLS glass surface via the water and SO₂ treatments, the mechanochemical properties of SLS glass surface become different depending on the RH. At lower humidity, the nano hardness of the Na⁺-leached surface is higher, and it can contribute to the enhanced wear resistance of SLS glass. In contrast, at higher humidity conditions, the SLS glass surface is more hydrophilic, and substantial wear debris can be found inside the wear track of SLS glass. Those phenomena suggest that adhesive wear and abrasive wear dominate the wear mechanism of SLS glass in humid air, causing the decreased wear resistance of SLS glass with increasing the RH. These results may not only provide a deep understanding of the wear mechanism of SLS glass but also helpful for operation process of functional and engineering glasses.

Keywords: soda lime silicate glass, wear, water, SO₂

Procedia PDF Downloads 143

Authors: Mohammed A. Sakr, Tarek M. Khalifa, Walid N. Mansour

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External bonding of fiber reinforced polymer (FRP) plates to reinforced concrete (RC) beams is an effective technique for flexural strengthening. This paper presents an analytical parametric study on the behavior of RC continuous beams flexurally strengthened with externally bonded FRP plates on the upper and lower fibers, conducted using simple uniaxial nonlinear finite element model (UNFEM). UNFEM is able to estimate the load-carrying capacity, different failure modes and the interfacial stresses of RC continuous beams flexurally strengthened with externally bonded FRP plates on the upper and lower fibers. The study investigated the effect of five key parameters on the behavior and moment redistribution of FRP-reinforced continuous beams. The investigated parameters were the length of the FRP plate, the width and the thickness of the FRP plate, the ratio between the area of the FRP plate to the concrete area, the cohesive shear strength of the adhesive layer, and the concrete compressive strength. The investigation resulted in a number of important conclusions reflecting the effects of the studied parameters on the behavior of RC continuous beams flexurally strengthened with externally bonded FRP plates.

Keywords: continuous beams, parametric study, finite element, fiber reinforced polymer

Procedia PDF Downloads 348

Authors: G. Mazor, I. Ladizhensky, A. Shapiro, D. Nemirovsky

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A lot of researches was dedicated to the evaluation of the efficiency of the uniform constant and temporary coatings enhancing a heat transfer rate. Our goal is an investigation of the sand coatings distributed by both uniform and non-uniform forms. The sand of different sizes (0.2-0.4-0.6 mm) was attached to a copper ball (30 mm diameter) surface by means of PVA adhesive as a uniform layer. At the next stage, sand spots were distributed over the ball surface with an areal density that ranges between one spot per 1.18 cm² (for low-density spots) and one spot per 0.51 cm² (for high-density spots). The spot's diameter value varied from 3 to 6.5 mm and height from 0.5 to 1.5 mm. All coatings serve as a heat transfer enhancer during the quenching in liquid nitrogen. Highest heat flux densities, achieved during quenching, lie in the range 10.8-20.2 W/cm², depending on the sand layer structure. Application of the enhancing coating increases an amount of heat, evacuated by highly effective nucleate and transition boiling, by a factor of 4.5 as compared to the bare sample. The non-uniform sand coatings were increasing the heat transfer rate value under all pool boiling conditions: nucleate boiling, transfer boiling and the most severe film boiling. A combination of uniform sand coating together with high-density sand spots increased the average heat transfer rate by a factor of 3.

Keywords: heat transfer enhancement, nucleate boiling, film boiling, transfer boiling

Procedia PDF Downloads 103

Authors: Esra Yuce, Isil D. S. Yamaner, Murude Yazan

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Aims and objective: Antiresorptive agents including bisphosphonates and denosumab as strong suppressors of osteoclasts are the most commonly used antiresorptive medications for the treatment of osteoporosis which counteract the negative quantitative alteration of trabecular and cortical bone by inhibition of bone turnover. Oral bisphosphonate therapy for the treatment of osteopenia, osteoporosis or Paget's disease is associated with the low-grade risk of osteonecrosis of the jaw, while higher-grade risk is associated with receiving intravenous bisphosphonates therapy in the treatment of multiple myeloma and bone metastases. On the other hand, there has been a remarkable increase in incidences of antiresorptive related osteonecrosis of the jaw (ARONJ) in oral bisphosphonate users. This clinical presentation will evaluate the healing outcomes via piezoelectric bone surgery under the irrigation of PVP-I solution irrigation in patients received bisphosphonate therapy. Material-Method: The study involved 8 female and 5 male patients that have been treated for ARONJ. Among 13 necrotic sites, 9 were in the mandible and 4 were in the maxilla. All of these 13 patients treated with surgical debridement via piezoelectric bone surgery under irrigation by solution with 3% PVP-I concentration in combination with long-term antibiotic therapy and 5 also underwent removal of mobile segments of bony sequestrum. All removable prosthesis in 8 patients were relined with soft liners during the healing periods in order to eliminate chronic minor traumas. Results: All patients were on oral bisphosphonate therapy for at least 2 years and 5 of which had received intravenous bisphosphonates up to 1 year before therapy with oral bisphosphonates was started. According to the AAOMS staging system, four cases were stage II, eight cases were stage I, and one case was stage III. The majority of lesions were identified at sites of dental prostheses (38%) and dental extractions (62%). All patients diagnosed with ARONJ stage I had used unadjusted removable prostheses. No recurrence of the symptoms was observed during the present follow-up (9–37 months). Conclusion: Despite their confirmed effectiveness, the prevention and treatment of osteonecrosis of the jaw secondary to oral bisphosphonate therapy remain major medical challenges. Treatment with piezoelectric bone surgery with irrigation of povidone-iodine solution was effective for management of bisphosphonate-related osteonecrosis of the jaw. Taking precautions for patients treated with oral bisphosphonates, especially also denture users, may allow for a reduction in the rate of developing osteonecrosis of the maxillofacial region.

Keywords: antiresorptive drug related osteonecrosis, bisphosphonate therapy, piezoelectric bone surgery, povidone iodine

Procedia PDF Downloads 236

Authors: Paul Dunst, Ing. Tobias Hemsel, Ing. Habil. Walter Sextro

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The use of fine powders with high cohesive and adhesive properties leads to challenges during transport, mixing and dosing in industrial processes, which have not been satisfactorily solved so far. Due to the increased contact forces at the transporting parts (e. g. pipe-wall and transport screws), conventional transport systems and also vibratory conveyors reach their limits. Often, flowability increasing additives that need to be removed again in later process steps are the only option to achieve wanted transport results. A rather new ultrasound-assisted powder transport system showed to overcome some of the issues by manipulating the effective friction between powder and transport pipe. Within this contribution, the transport mechanism will be introduced shortly, together with preliminary transport results. As the tangential force of the transport pipe and the powder is the main influencing factor within the transport process, a test stand for measuring tangential forces of a powder-wall contact in the presence of an ultrasonic vibration orthogonal to the contact plane was built. Measurements for a sample powder show that the effective tangential force can already be significantly reduced at very low ultrasonic amplitude. As a result of the measurements, an empirical model for the relationship of tangential force, contact parameters and ultrasonic excitation is presented. This model was used to adjust the driving parameters of the powder transport system, resulting in better performance.

Keywords: powder transport, ultrasound, friction, friction manipulation, vibratory conveyor

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Authors: Jitendra Narayan Panda, Jayashree Bijwe, Raj K. Pandey

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PAEK (Polyaryl ether ketone) being a high-performance polymer, is currently being explored for its tribo-potential by incorporating various fibers, solid lubricants. In this work, influence of amount (30 and 40 %) of short glass fibers (GF) in two composites containing PAEK (60 and 50 %) and synthetic graphite (10 %) on mechanical and tribological behaviour was studied. The composites were developed by injection molding and evaluated in adhesive wear mode (pin on disc configuration) against mild steel disc. The load and speed were selected as variable input parameters while coefficient of friction (µ), specific wear rate (K0) and PVlimit (pressure × velocity) values were selected as output parameters for performance evaluation. Although higher amount of GF lead to better mechanical properties, tribological properties were not in tune to this. Overall, µ and K0 for both composites were in the range 0.04-0.08 and 3-8x 10-16 m3/Nm respectively and decreased with increase in applied PV values till failure was observed. PVlimit was indicated by 112 and 100 MPa m/s. Such high PVlimit values are not reported for any polymer composites running in dry conditions in the literature. The mechanical properties of the C40 composite (40 % GF) proved superior to C30 composite (30 % GF). However, all tribological properties of C40 were inferior to C30. It exhibited higher µ, higher K0 and slightly lower PVlimit value. The higher % fibers proved detrimental for tribo-performance and worn surface analysis by SEM & EDAX was done on the discs & pins to understand wear mechanisms.

Keywords: PAEK composites, pin-on-disk, PV limit, friction

Procedia PDF Downloads 161

Authors: Chandrashekhar Bhat, Dilifa Jossley Noronha, Faber A. Saldana

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Transportation of long turbine blades from one place to another is a difficult process. Hence a feasibility study of modularization of wind turbine blade was taken from structural standpoint through finite element analysis. Initially, a non-segmented blade is modeled and its structural behavior is evaluated to serve as reference. The resonant, static bending and fatigue tests are simulated in accordance with IEC61400-23 standard for comparison purpose. The non-segmented test blade is separated at suitable location based on trade off studies and the segments are joined with an innovative double strap bonded joint configuration. The adhesive joint is modeled by adopting cohesive zone modeling approach in ANSYS. The developed blade model is analyzed for its structural response through simulation. Performances of both the blades are found to be similar, which indicates that, efficient segmentation of the long blade is possible which facilitates easy transportation of the blades and on site reassembling. The location selected for segmentation and adopted joint configuration has resulted in an efficient segmented blade model which proves the methodology adopted for segmentation was quite effective. The developed segmented blade appears to be the viable alternative considering its structural response specifically in fatigue within considered assumptions.

Keywords: modularization, fatigue, cohesive zone modeling, wind turbine blade

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Authors: B. Almassri, F. Almahmoud, R. Francois

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Near surface mounted reinforcement (NSM) technique is one of the promising techniques used nowadays to strengthen reinforced concrete (RC) structures. In the NSM technique, the Carbon Fibre Reinforced Polymer (CFRP) rods are placed inside pre-cut grooves and are bonded to the concrete with epoxy adhesive. This paper studies the non-classical mode of failure ‘the separation of concrete cover’ according to experimental and numerical FE modelling results. Experimental results and numerical modelling results of a 3D finite element (FE) model using the commercial software Abaqus and 2D FE model FEMIX were obtained on two beams, one corroded (25 years of corrosion procedure) and one control (A1CL3-R and A1T-R) were each repaired in bending using NSM CFRP rod and were then tested up to failure. The results showed that the NSM technique increased the overall capacity of control and corroded beams despite a non-classical mode of failure with separation of the concrete cover occurring in the corroded beam due to damage induced by corrosion. Another FE model used external steel stirrups around the repaired corroded beam A1CL3-R which failed with the separation of concrete cover, this model showed a change in the mode of failure form a non-classical mode of failure by the separation of concrete cover to the same mode of failure of the repaired control beam by the crushing of compressed concrete.

Keywords: corrosion, repair, Reinforced Concrete, FEM, CFRP, FEMIX

Procedia PDF Downloads 139

Authors: Ahmed Moulay, Mariia Zhuldybina, Mirko Torres, Mike Rozel, Ngoc Duc Trinh, Chloé Bois

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Hybrid printed electronics technology (HPE) provides innovative opportunities to enhance conventional electronics applications, which are often based on printed circuit boards (PCB). By combining the best of both performance from conventional electronic components and the flexibility from printed circuits makes it possible to manufacture HPE at high volumes using roll-to-roll printing processes. However, several challenges must be overcome in order to accurately integrate an electronic component on a printed circuit. In this presentation, we will demonstrate the integration process of electronic components from the lab scale to the industrialization. Both the printing quality and the integration technique must be studied to define the optimal conditions. To cover the parameters that influence the print quality of the printed circuit, different printing processes, flexible substrates, and conductive inks will be used to determine the optimized printing process/ink/substrate system. After the systems is selected, an electronic component of 2.5 mm2 chip size will be integrated to validate the functionality of the printed, electronic circuit. Critical information such as the conductive adhesive, the curing conditions, and the chip encapsulation will be determined. Thanks to these preliminary results, we are able to demonstrate the chip integration on a printed circuit using industrial equipment, showing the potential of industrialization, compatible using roll-to-roll printing and integrating processes.

Keywords: flat bed screen-printing, hybrid printed electronics, integration, large-scale production, roll-to-roll printing, rotary screen printing

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Authors: Yilei Xue, Yat-Hing Ham, Wenting Qiu, Wan Chan, Stefan Nagl

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Polydopamine (PDA) is a popular material in biological and medical applications due to its excellent biocompatibility, outstanding physicochemical properties, and facile fabrication. In this project, a new sandwich-structured PDA and silver (Ag) hybrid material named PDA-Ag-PDA was synthesized and characterized layer-by-layer, where silver nanoparticles (Ag NPs) are wrapped in PDA coatings, using SEM, AFM, 3D surface metrology, and contact angle meter. The silver loading capacity is positively proportional to the roughness value of the initial PDA film. This designed film was subsequently integrated within a digital microfluidic (DMF) platform coupling with an oxygen sensor layer for on-chip antibacterial assay. The concentration of E. coli was quantified on DMF by real-time monitoring oxygen consumption during E. coli growth with the optical oxygen sensor layer. The PDA-Ag-PDA coating shows an 99.9% reduction in E. coli population under non-nutritive condition with 1-hour treatment and has a strong growth inhibition of E. coliin nutrient LB broth as well. Furthermore, PDA-Ag-PDA film maintaining a low cytotoxicity effect to human cells. After treating with PDA-Ag-PDA film for 24 hours, 82% HEK 293 and 86% HeLa cells were viable. The SERS enhancement factor of PDA-Ag-PDA is estimated to be 1.9 × 104 using Rhodamine 6G (R6G). Multifunctional PDA-Ag-PDA coating provides an alternative platform to conjugate biomolecules and perform biological applications on DMF, in particular, for the adhesive protein and cell study.

Keywords: polydopamine, silver nanoparticles, digital microfluidic, optical sensor, antimicrobial assay, SERS

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Authors: Chia-Yen Lee, Hao-Jen Wang, Jhih-Hao Lai

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In recent years, infrared (IR) imaging has been considered as a potential tool to assess the efficacy of chemotherapy and early detection of breast cancer. Regions of tumor growth with high metabolic rate and angiogenesis phenomenon lead to the high temperatures. Observation of differences between the heat maps in long term is useful to help assess the growth of breast cancer cells and detect breast cancer earlier, wherein the multi-time infrared image alignment technology is a necessary step. Representative feature points detection and matching are essential steps toward the good performance of image registration and quantitative analysis. However, there is no clear boundary on the infrared images and the subject's posture are different for each shot. It cannot adhesive markers on a body surface for a very long period, and it is hard to find anatomic fiducial markers on a body surface. In other words, it’s difficult to detect and match features in an IR sequence images. In this study, automated feature detection and matching algorithms with two type of automatic feature points (i.e., vascular branch points and modified Harris corner) are developed respectively. The preliminary results show that the proposed method could identify the representative feature points on the IR breast images successfully of 98% accuracy and the matching results of 93% accuracy.

Keywords: Harris corner, infrared image, feature detection, registration, matching

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Authors: Amina Ben Abla, Sylvie Changotade, Geraldine Rohman, Guilhem Boeuf, Cyrine Dridi, Ahmed Elmarjou, Florence Dufour, Didier Lutomski, Abdellatif Elm’semi

Abstract:

Understanding cell adhesion and interaction with the extracellular matrix is essential for biomedical and biotechnological applications, including the development of biomaterials. In recent years, numerous biomaterials have emerged and were used in the field of tissue engineering. Nevertheless, the lack of interaction of biomaterials with cells still limits their bio-integration. Thus, the design of bioactive biomaterials to improve cell attachment and proliferation is of growing interest. In this study, bio-functionalized material was developed combining a synthetic polymer scaffold surface with selected domains of type III human fibronectin (FNIII-DOM) to promote cell adhesion and proliferation. Bioadhesive ligand includes cell-binding domains of human fibronectin, a major ECM protein that interacts with a variety of integrins cell-surface receptors, and ECM proteins through specific binding domains were engineered. FNIII-DOM was produced in bacterial system E. coli in 5L fermentor with a high yield level reaching 20mg/L. Bioactivity of the produced fragment was validated by studying cellular adhesion of human cells. The adsorption and immobilization of FNIII-DOM onto the polymer scaffold were evaluated in order to develop an innovative biomaterial.

Keywords: biomaterials, cellular adhesion, fibronectin, tissue engineering

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Authors: Chan Park, Sang-Won Park, Kwi-Dug Yun, Hyun-Pil Lim

Abstract:

Purpose: Plasma treatment under various conditions has been studied to increase the bonding strength and surface sterilization of dental ceramic materials. We assessed the evolution of the shear bond strength (SBS) and antimicrobial effect of nonthermal atmospheric pressure plasma (NTAPP) treatment over time. Methods: Presintered zirconia specimens were manufactured as discs (diameter: 15 mm, height: 2 mm) after final sintering. The specimens then received a 30-min treatment with argon gas (Ar², 99.999%; 10 L/min) using an NTAPP device. Five post-treatment intervals were evaluated: control (no treatment), P0 (within 1 h), P1 (24 h), P2 (48 h), and P3 (72 h). This study investigated the surface characteristics, SBS of two different resin cement (RelyXTM U200 self-adhesive resin cement, Panavia F2.0 methacryloyloxydecyl dihydrogen phosphate (MDP)-based resin cement), and Streptococcus mutans biofilm formation. Results: The SBS of RelyXTM U200 increased significantly (p < 0.05) within 2 days following plasma treatment (P0, P1, P2). For Panavia F 2.0, a significant decrease (p < 0.05) was detected only in the group that had undergone cementation immediately after plasma treatment (P0). S. mutans adhesion decreased significantly (p < 0.05) within 2 days of plasma treatment (P0, P1, P2) compared to the control group. The P0 group displayed a lower biofilm thickness than the P1 and P2 groups (p < 0.05). Conclusions: After NTAPP treatment of zirconia, the effects on bonding strength and antimicrobial growth persist for a limited duration. The effect of NTAPP treatment on bonding strength depends on the resin cement.

Keywords: NTAPP, SBS, antimicrobial effect, zirconia

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Authors: Abdul Karim Zulkarnain, Marchaban, Subagus Wahyono, Ratna Asmah Susidarti

Abstract:

Mahkota Dewa contains phalerin which has activity as sun screen. In this study, 13 formulations of cream oil in water (o/w) were prepared and tested for their physical characteristics. The physical characteristics were then used for determining the optimum formula. This study aimed to explore the physical stability of optimized formulation of cream, its sun protecting factor (SPF) values using in vitro and in vivo tests. The optimum formula of o/w cream were prepared based on Simplex Lattice Design (LSD) method using software Design Expert®. The formulation of o/w cream were varied based on the proportion of cetyl alcohol, mineral oil and tween 80. The difference of physical characteristic of optimum and predicted formula was tested using t-test with significant level of 95%. The optimum formula of o/w cream was the formula which consists of cetyl alcohol 9.71%, mineral oil, 29%, and tween 80 3.29. Based on t-test, there was no significant difference of physical characteristics of optimum and predicted formulation. Viscosity, spread power, adhesive power, and separation volume ratio of o/w at week 0-4 were relatively stable. The o/w creams were relatively stable at extreme temperature. The o/w creams from mahkota dewa, phalerin, and benzophenone have SPF values of 21.32, 33.12, and 42.49, respectively. The formulas did not irritate the skin based on in vivo test.

Keywords: cream, stability, In vitro, In vivo

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Authors: Erma Desmaliana, Saptahari Sugiri

Abstract:

Limited availability of solid timber in large dimensions becomes a problem. The demands of timbers in Indonesia is more increasing compared to its supply from natural forest. It is associated with the issues of global warming and environmental preservation. The uses of timbers from HTI (Industrial Planting Forest) and HTR (Society Planting Forest), such as Jabon, is an alternative source that required to solve these problems. Having shorter lifespan is the benefit of HTI/HTR timbers, although they are relatively smaller in dimension and lower in strength. Engineering Wood Product (EWP) such as glulam (glue-laminated) timber, is required to overcome their losses. Glulam is fabricated by gluing the wooden planks that having a thickness of 20 to 45 mm with an adhesive material and a certain pressure. Glulam can be made a curved beam, is one of the advantages, thus making it strength is greater than a straight beam. This paper is aimed to know the material behavior of curved glue-laminated beam of Jabon timber. Preliminary methods was to gain physical and mechanical properties, and glue spread strength of Jabon timber, which following the ASTM D-143 standard test method. Dimension of beams were 50 mm wide, 760 mm span, 50 mm thick, and 50 mm rise. Each layer of Jabon has a thickness of 5 mm and is glued with polyurethane. Cold press will be applied to beam laminated specimens for more than 5 hours. The curved glue-laminated beams specimens will be tested about the bending behavior. This experiments aims to obtain the increasing of load carrying capacity and stiffness of curved glulam beam.

Keywords: curved glulam beam, HTR&HTI, load carrying, strength

Procedia PDF Downloads 271

Authors: A. Cheriguene, F. Chougrani

Abstract:

A total of 120 wild lactic acid bacteria were isolated from goat’s milk collected from different areas in Western Algeria. The strains were screened for production and technological properties such as acid production, aminopeptidase activity, autolytic properties, antimicrobial activity, and exopolysaccharide production. In general most tested isolates showed a good biomass separation when collected by centrifugation; as for the production of the lactic acid, results revealed that our strains are weakly acidifying; nevertheless, lactococci showed a best acidifying activity compared to lactobacilli. Aminopeptidase activity was also weak in most strains; but, it was generally higher for lactobacilli compared to lactococci. Autolytic activity was generally higher for most strains, more particularly lactobacilli. Antimicrobial activity was detected in 50% of the isolates, particularly in lactobacilli where 80% of strains tested were able to inhibit the growth of other strains. The survey of the profile of the texture, the proteolysis as well as the development of the flavor in the Domiati cheese made on the basis of our isolated strains have been led during the ripening. The sensory assessment shows that the cheese salted in milk received the best scores in relation to cheese salted after drainage. Textural characteristics, such as hardness, cohesiveness, gumminess, and chewiness decreased in the two treatments during the 60 days of ripening. Otherwise, it has been noted that adhesiveness and adhesive force increased in the cheese salted in milk.

Keywords: lactic acid bacteria, technological properties, acidification, exopolysaccharide, bacteriocin, textural properties

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Authors: Elad Arad, Raz Jelinek, Hanna Rapaport

Abstract:

Amyloidoses are a family of diseases characterized by abnormal protein folding that leads to aggregation. They accumulate to form fibrillar plaques which are implicated in the pathogenesis of Alzheimer, prion, diabetes type II and other diseases. To the best of our knowledge, despite extensive research efforts devoted to plaque aggregates inhibition, there is yet no cure for this phenomenon. Titanium and its alloys are found in growing interest for biomedical applications. Variety of surface modifications enable porous, adhesive, bioactive coatings for its surface. Titanium oxides (titania) are also being developed for photothermal and photodynamic treatments. Inspired by this, we set to explore the effect of functionalized titania nanoparticles in combination with external stimuli, as potential photothermal ablating agents against amyloids. Titania nanoparticles were coated with bi-functional catechol derivatives (dihydroxy-phenylalanine propanoic acid, noted DPA) to gain targeting properties. In conjunction with UV-radiation, these nanoparticles may selectively destroy the vicinity of their target. Titania modified 5 nm nanoparticles coated with DPA were further conjugated to the amyloid-targeting Congo Red (CR). These Titania-DPA-CR nanoparticles were found to target mature amyloid fibril of both amyloid-β (Aβ 1-42 a.a). Moreover, irradiation of the peptides in presence of the modified nanoparticles decreased the aggregate content and oligomer fraction. This work provides insights into the use of modified titania nanoparticles for amyloid plaque targeting and photothermal destruction. It may shed light on future modifications and functionalization of titania nanoparticles for different applications.

Keywords: titanium dioxide, amyloids, photothermal treatment, catechol, Congo-red

Procedia PDF Downloads 115

Authors: Yang Xiao-Jun, Yu Tian-Hao, Hu Ying-Qi

Abstract:

Breathing in foreign objects during the operation of the aircraft engine, impurities in the aircraft fuel and products of incomplete combustion can produce deposits on the surface of the turbine blades. These deposits reduce not only the turbine's operating efficiency but also the life of the turbine blades. Based on the small open wind tunnel, the simulation of deposits on the leading edge of the turbine has been carried out in this work. The effect of film cooling on particulate deposition was investigated. Based on the analysis, the adhesive mechanism for the molten pollutants’ reaching to the turbine surface was simulated by matching the Stokes number, TSP (a dimensionless number characterizing particle phase transition) and Biot number of the test facility and that of the real engine. The thickness distribution and growth trend of the deposits have been observed by high power microscope and infrared camera under different temperature of the main flow, the solidification temperature of the particulate objects, and the blowing ratio. The experimental results from the leading edge particulate deposition demonstrate that the thickness of the deposition increases with time until a quasi-stable thickness is reached, showing a striking effect of the blowing ratio on the deposition. Under different blowing ratios, there exists a large difference in the thickness distribution of the deposition, and the deposition is minimal at the specific blow ratio. In addition, the temperature of main flow and the solidification temperature of the particulate have a great influence on the deposition.

Keywords: deposition, experiment, film cooling, leading edge, paraffin particles

Procedia PDF Downloads 122