bluuebunny/crossref_metadata_2025 huggingface dataset:
A Rapid Quantitative Analysis of Native Antioxidants in Natural Rubber (Hevea brasiliensis) During Maturation
Authors: Musigamart Natedao , Liengprayoon Siriluck , Klanarong Sriroth , Dubreucq Eric , Lecomte Jerome , Vaysse Laurent
Published: November 2013

Natural rubber (NR) obtained from H. brasiliensis is known to be susceptible to oxidative degradation according to the amount of double bonds in the structure of the polymer, i.e. poly (cis-1,4-isoprene) [1]. However NR has been reported to contain native antioxidants such as phytosterols, phospholipids and tocotrienols [2]. Among those, γ-tocotrienol, present in hevea latex was reported to exhibit “in-vitro” antioxidant activity [3]. However the direct involvement of γ-tocotrienol or other antioxidants naturally present in NR in the protection of NR against oxidation is difficult to assess as the works were carried out with different of rubber types and in different conditions [4,5]. In the framework of a work on the dynamics of γ-tocotrienols in NR samples obtained from coagula maturated during several durations (0 to 15 days) in parallel with measurement of standard properties such as P0 and PRI, methodological development of the analysis of tocotrienols and derivatives is presented in this study.HPLC-MS has been shown to be an accurate technique for lipid analysis in NR [6]. However, this is a time-consuming technique especially with large number of samples due to a necessary step of saponification. Moreover, the structures of γ-tocotrienol and its dimers were found to be affected by the strong alkali condition of saponification (data not shown). Therefore a rapid quantitative method for γ-tocotrienol from NR using high performance thin layer chromatography (HP-TLC) has been developed. Lipid extracts from NR samples could be simply analyzed by HP-TLC without any derivatization and the detectable quantity could be in nanogram range. Statistical analysis of the data showed that the method is precise, accurate, reproducible and sensitive. Thus the proposed HP-TLC method can be successfully used for the quantification of γ-tocotrienol from NR samples. This technique will be useful to conduct further experiments on antioxidant activity of NR lipids and to relate the results with physical properties of NR, especially those linked to resistance to oxidation.
Mesostructure Evolution during Storage of Rubber Films from Washed Cream Latex and Skim Latex
Authors: Thepchalerm Chalao , Wisunthorn Suwaluk , Vaysse Laurent , Kiatkamjornwong Suda , Nakason Charoen , Bonfils Frederic
Published: November 2013

Fresh field latex (FL) of Hevea brasiliensis was centrifuged to separate the major compartments: (i) the cream, (ii) the skim plus the C-serum, and (iii) the bottom fraction. Cream was dispersed in distilled water to prepare cream washed latex or CL sample. Skim was collected together with C-serum to prepare the skim latex or SKL sample. Then, films were made from FL, CL and SKL. The mesostructure (macromolecular structure and aggregates or gel) of the natural rubber films was studied by size exclusion chromatography coupled to a multiangular light scattering detector (SEC-MALS). The mesostructure was analyzed on fresh films and on films stored in the laboratory for three months (slow structuring). This study showed that FL and CL films had bimodal elution profiles of long and short polyisoprene chains as revealed by the two peaks on the chromatograms at low and high elution volumes, respectively. On the contrary, SKL films exhibited unimodal elution profiles at low elution volume and a highly abnormal molar masses elution profiles. After 3 months storage, the mesostructure of FL evolved dramatically especially the number-average molar masses (Mn), which increased by 60%. The mesostructure of CL films evolved at a lesser extent and, the mesostructure of SKL films exhibited no significant change. These results indicated (i) the skim rubber particles are not prone to slow structuring during storage in presence of serum and (ii) some constituents either in the serum or/and in the bottom fraction could still be present with cream and be involved in the slow structuring of cream particles latex.
Application of NR Gloves Reclaim: Cure and Mechanical Properties of NR/Reclaim Rubber Blends
Authors: Saiwari Sitisaiyidah , Lohyi Eman , Nakason Charoen
Published: November 2013

Reclamation of waste natural rubber gloves is carried out by mechano-chemical process using MBTS as reclaiming agent. The reclaim rubber is later blended with a virgin natural rubber at various blend ratios. The cure behavior and mechanical properties of the re-vulcanized blends are evaluated in comparison to the properties profile of the virgin materials. A significant increase in re-vulcanization rate is observed with increasing reclaim rubber contents. This property is most likely a consequence of the presence of active functional sites in the reclaim rubber. Additionally, the maximum torque as well as a torque difference increase with increasing reclaims rubber contents which are attributed to an increase in crosslink density of the blends. Moreover, the crosslink density also plays a major role in mechanical properties of the NR/reclaim rubber blends.
Ecological Roofing Tiles Made with Rubber and Plastic Wastes
Authors: Gaggino Rosana , Positieri María Josefina , Irico Patricia , Kreiker Jerónimo , Arguello Ricardo , Sánchez María Paz Amono
Published: November 2013

The general objective of this research work was to contribute to the environmental decontamination. Its specific objective was to develop sustainable roofing tiles from the ecological, technical and economical points of view.These roofing tiles are made from recycled materials such as plastics from industry, and rubber from tires into disuse. In this way this technology contributes in the decontamination of the environment, since it uses waste materials that are buried in municipal land without any use, or accumulated and burned in landfills, causing pollution. The procedure used was the thermo-molding compaction. The available amounts of plastic waste are abundant. According to data provided in 2012 by the Ministry of Health and Environment of Argentina, Argentina produces 1,639 tons / year. The available amounts of rubber tires are also abundant. According to data provided in 2012 by the National Institute of Industrial Technology -INTI, Argentina generates more than 100,000 tons / year. Plastics and rubber are non bio-degradables materials, so nature can not absorb them as other waste. One purpose of this research work was to provide an alternative to other traditional building technologies that consume non-renewable resources, or produce negative environmental impact. The main technical advantages of these roofing tiles respect to other traditional such as ceramic or concrete tiles are their excellent resistance to hail and freezing, high flexural resistance, low specific weight, and low water absorption.
Cosmetic Pore Packs from Deproteinized Natural Rubber Latex
Authors: Pichayakorn Wiwat , Boonme Prapaporn , Taweepreda Wirach
Published: November 2013

Natural rubber latex (NRL) from Hevea brasiliensis consists of cis-1,4-polyisoprene that have many excellent physical properties such as high elasticity, tensile strength, and easily film-forming. However, some proteins in NRL can cause allergy. Hence, this research aimed to prepare cosmetic pore packs from deproteinized NRL (DNRL) that was prepared in-house by enzyme treatment and centrifugation processes. The properties of DNRL were evaluated in terms of amount of remained protein, pH, particle size, polydispersity index, and zeta potential. This DNRL was then formulated the pore pack products by mixing with the other ingredients and casting to the film form. An appropriate pore pack formulation composed of sodium alginate and polyvinylpyrrolidone K30 mixed with DNRL to produce films with good properties. Hydroxypropylmethylcellulose was also added to another formulation for improving toughness of the films. Both products had similar appearance and physical properties such as thickness, uniformity of weight, pH, tensile strength, and elongation at break, but lower peel strength comparing with the commercial pore pack product. These films showed good flexibility, softness, and toughness. After storage at room temperature for a month, there were no different in appearance and pH that presented good stability. The obtained pore packs also exhibited desirable characteristics with acceptable volunteer satisfactions. However, they should be improved for more adhesiveness in further study. In conclusion, DNRL could be used as major component for cosmetic pore pack preparations.
Deproteinized Natural Rubber as Chewing Gum Base for Nicotine Delivery
Authors: Pichayakorn Wiwat , Boonme Prapaporn , Taweepreda Wirach
Published: November 2013

This study aimed to prepare the nicotine chewing gums for smoking cessation using deproteinized natural rubber latex (DNRL) as gum bases due to its highly flexible property. The formulations were produced by the conventional heat melting and kneading methods. The experimental design was used to obtain the optimum 3 gum base formulations. Each formulation composed of olive oil as a plasticizer; sodium carboxymethylcellulose as an adsorbent; xylitol, mannitol and saccharin sodium as sweeteners instead of sugar. Gum base 1 and gum base 2 had the same sweetener amount but gum base 2 had the lower plasticizer amount, while gum base 1 and gum base 3 had the same plasticizer amount but different sweetener amount. Nicotine was added into each 3 gum bases (NCT1-3). The results showed no significant difference of appearance and taste. Their physicochemical properties were as following: pH of 8.45, 8.46, 8.54, hardness of 39.80, 36.28, 33.14 Shore A, initial modulus of 0.090, 1.260, 0.065 MPa, %elongation of 286, 403, 489%, drug content of 63.62, 70.95, 72.70%, and drug release when 500 times for force clamping of 48.72, 45.72, 67.74%, respectively. After storage at room temperature for 1 month, NCT1 and NCT2 showed unchangeable appearance, but NCT3 showed the slightly liquefied film and much sticky due to hygroscopic property of its sweetener. However, all formulations showed the significant reduction of drug amount which should be further improved in their stability properties.
Drying of Rubber Sheet Using Impingement of Multiple Hot Air Jets
Authors: Nuntadusit Chayut , Waehahyee Makatar
Published: November 2013

In the process for producing ribbed smoked rubber sheet, the rubber sheet drying is the most time and energy consumption process. This research study the possibility in develop new drying system using array of hot air jets impinging directly on rubber sheet in order to reduce time for drying rubber in smoked room and increase productivity of rubber sheets. In the study, the array of jets from jet plate with drilled jet holes in staggered arrangement impinged on the both side of rubber sheet. The effects of jet velocity (Vj=10, 16, 23 m/s), jet temperature (Tj=50, 60, 70°C) and the distance from jet outlet to rubber surface (L=4D, 6D, 8D which D is diameter of jet hole) on drying rate were investigated by measuring weight of rubber sheet change with time. The heat transfer rate on impinged surface was also measured by attaching a heat flux sensor on impinged wall. The results showed that the convective heat transfer coefficient increased when the jet velocity was increased and when the distance from jet was decreased particularly in jet directly impinged region. It was found that the enhancement in heat transfer rate from jets cannot increase the rubber drying rate for all cases because the drying rate depend on rubber property. The process of rubber sheet drying can be divided in 2 periods; in the first drying period, the drying rate decreases with decreased moisture content. The drying rate depended on the initial moisture content and the condition of external effect such as jet velocity, jet temperature and distance from jet outlet to rubber surface. In second drying period, the moisture content is below 20% dry basis. In this period, the drying rate is almost constant near zero. It was also found that the drying for case of L=6D was higher than case of L=4D and 8D. The optimum condition for rubber sheet drying without defects on rubber property after drying was L=6D and Tj=70°C.
Phase Morphology, Thermal and Mechanical Properties of Compatibilized Nylon12/Natural Rubber Blends Using PS/MNR
Authors: Saengthaveep Saravalee , Jana Sadhan C. , Magaraphan Rathanawan
Published: November 2013

To produce a tough material for application demanding high impact resistance and low moisture absorption, melt blending of Nylon12 (Polyamide 12, PA12) and natural rubber (NR) was carried out in a brabender plasticorder at 210 °C with rotor speed of 70 rpm in the presence of polystyrene/maleated natural rubber (PS/MNR) blend as a compatibilizer. The effect of compatibilizer content (1, 3, 5, 7 and 10 phr) on phase morphology, thermal, and mechanical properties of [Nylon12/NR]/[PS/MNR] blends was investigated by using SEM, DSC, and Izod impact tester, respectively. The result revealed that PS/MNR blend improved the compatibility of Nylon12/NR blends efficiently due to the presence of amide linkage at the interfaces from the reaction between the reactive groups of MNR and the NH2 end groups of Nylon12 during mixing. A fine phase morphology (good dispersion and small dispersed phase size of NR domains in Nylon12 matrix) of [Nylon12/NR]/[PS/MNR] blends was observed at the optimum compatibilizer content of 7 phr, relating to the improvement of mechanical property. The impact energy of [Nylon12/NR]/[PS/MNR] blends was 503 J/m higher than that of neat Nylon12 (115 J/m) and Nylon12/NR binary blend (241 J/m) due to the toughening effect of rubber and proper morphology. The melting temperature of all blends did not change obviously from thermal analysis. However, the presence of rubber particle obstructed the crystallization of Nylon12 phase, leading to the decreasing of %crystallinity from 93% to around 70%.
The Influence of Rainfall on Growth of Rubber Trees in Marginal Area of Northeast Thailand
Authors: Sangchanda Niramol , Ayutthaya Supat Isarangkool Na , Meetha Somyot , Songsri Patcharin
Published: November 2013

Rubber trees grow predominately in the southern and eastern areas of Thailand, where there is the majority of rainfall. However, the rubber tree plantations extend to north and northeastern areas, with lower annual rainfall. The aim of this study was to evaluate the effect of rainfall on growth of rubber tree in northeastern areas of Thailand. The outcome of this work should be helped to indicate the optimum area for rubber tree planting in northeast. The study was undertaken using rubber tree clone RRIM600 by comparing the girth at 150 cm at the soil surface, planted in areas of differing rainfall: in Nongkhai, Chaiyaphum, Khon Kaen, Roiet and Buriram provinces. The sample of 50 trees was selected in 3 plantations per province (150 trees per province). The results found that there was no significant difference in girth of the rubber trees in all areas. However, the rubber trees planted in Nongkhai, where had highest rainfall, had highest growth. Moreover, the relationship between rainfall and growth exhibited a positive correlation, demonstrating that higher rainfall increased the girth of rubber trees.
Influence of Blend Proportions on Properties of ENR-25/TPU Simple Blends
Authors: Pichaiyut Skulrat , Nakason Charoen , Kalkornsurapranee Ekwipoo , Vennemann Norbert , Kummerlöwe Claudia
Published: November 2013

Thermoplastic natural rubber (TPNR) based on blending of thermoplastic polyurethane (TPU) and epoxidized natural rubber with 25 mol % epoxide (ENR-25) was prepared by simple blend technique. Influence of various blend proportions was investigated. It was found that an incorporation of rubber caused decreasing of mechanical properties in terms of tensile strength, elongation at break and hardness. This is attributed to incorporation of rubber phase may cause chain restriction of the soft segments in TPU and hence lower elongation at break and tensile strength. It was also found that the tension set value decreased with increasing proportion of natural rubber which indicates greater elasticity or tendency to recover to the original shape after prolonged deformation. Additionally, shear stress and shear viscosity of the blends increased with increasing rubber proportions due to higher viscosity of the ENR-25 component which leads to higher force to compress the polymer melt flowing through a capillary channel. Morphological properties of the simple blend with various blend proportions exhibited formation of co-continuous phase structure was observed where larger rubber formation are observed in the blend with higher content of ENR-25 phase.
Study of some Dental Biomaterials Properties Using an Original Software Application
Authors: Prejmerean Vasile , Silaghi-Dumitrescu Laura , Prodan Doina , Prejmerean Cristina , Moldovan Marioara
Published: November 2013

The aim of the present study is to measure the optical properties of dental materials, color and translucency, as well as their radiopacity using digital images. To do this, an original software application implementing two functions has been developed. Determining the radiopacity amount of certain areas of the materials is achieved by interpolating the values of ten aluminum plates used as reference. The study of this property is achieved by interpreting the statistical results and graphs displayed. The translucency value was calculated as the difference of the CIELab color system values for two digital images representing the same material on white and black background, respectively. In order to evaluate the color changes of the biomaterials, the samples were immersed in coffee, wine and orange juice. The application has been tested on several experimental materials based on bioceramics, dental composites and giomers, and the results are similar to the ones obtained using other evaluation methods.
Exploring Zinc Apatites through Different Synthesis Routes
Authors: Brangule Agnese , Gross K. , Komarovska Laura , Vīksna Arturs
Published: November 2013

nclusion of zinc in apatites is not completely understood due to complexes in solution preventing the incorporation or the inclusion of defects. Some work has shown zinc addition by alternative synthesis routes, but the level of incorporation has not been reassessed. This work uses a newly developed approach whereby zinc is included in an amorphous phase and subsequently crystallized. Different phosphate reactants (ammonium, sodium or potassium phosphates) were mixed together with calcium salts (calcium nitrate or calcium acetate) and the pH level adjusted (with ammonia or KOH) to investigate the ease of forming an amorphous phase and the inclusion of zinc. X-ray diffraction revealed that all reactants showed a tendency to form an amorphous phase, supporting the requirement of a high pH to prevent crystallization. X-ray fluorescence showed higher inclusion in the absence of ammonia. Potassium phosphate led to the highest zinc incorporation, accompanied by simultaneous inclusion of potassium. Crystallization at 700 °C indicated that zinc levels close to 20% replacement of calcium were the highest possible before the onset of tricalcium phosphate formation. FTIR-DRIFT showed a change in bonding conditions at higher zinc concentrations. This work shows the importance of reactants for including zinc, the larger zinc inclusion accompanied by potassium and zinc levels that can maintain the apatite structure.
Fish Scales as a Biocomposite of Collagen and Calcium Salts
Authors: Sionkowska Alina , Kozlowska Justyna
Published: November 2013

Collagen for biomedical applications is mainly isolated from animal tissues (bovine or porcine skin and bovine or equine Achilles tendons). Type I collagen has been also extracted from skin, bone, fins and scales of fresh water and marine fishes. Fish scales are composed of collagen covered with calcium salts. In the present study we report the preparation of collagen from fish scales for potential cosmetic, pharmaceutical and implant applications. In our laboratory collagen was isolated from scales of Esox lucius. It was the first time that this species were used as sources of collagen. Extraction of collagen from fish scales was done in two steps. In the first step, fish scales were demineralized using EDTA. Energy dispersive X-ray analysis of demineralized scale was carried out for quantitative estimation of inorganic content. Then, demineralized fish scales were dissolved in acetic acid. Collagen isolated from Esox Lucius may serve as an attractive and safe source of collagen for biomedical and pharmaceutical applications. Fish collagen can be processed in sheet, sponges foams, injectable viscous solution, and dispersions.
Silk Fibroin/Nano-CaP Bilayered Scaffolds for Osteochondral Tissue Engineering
Authors: Yan Le Ping , Oliveira Joaquim Miguel , Oliveira Ana L. , Reis Rui L.
Published: November 2013

In this study, bilayered silk and silk/nanoCaP scaffolds were developed for osteochondral tissue engineering. Aqueous silk solution (16 wt.%) was used for preparation of the cartilage-like layer and, for generation of the silk/nanoCaP suspension and the bottom layer (CaP/Silk: 16 wt.%). The scaffolds were formed by using salt-leaching/lyophilization approach. The scanning electron microscopy revealed that the both layers presented porous structure and integrated well. Micro-computed tomography images confirmed that the CaP phase was only retained in the silk/nanoCaP layer. The hydration degree and mechanical properties of the bilayered scaffold were comparable to the ones of each single layer. The apatite crystal formation was limited to the silk/nanoCaP layer, when soaking the scaffold in a simulated body fluid solution, which is a must for the application of the developed scaffolds in OC tissue engineering.
CO2 Laser Assisted Processing of Bioactive Titanium-Based Surfaces
Authors: Gräf Stephan , Müller Frank A.
Published: November 2013

The surface of Ti6Al4V alloys was activated by a selective laser microstructuring and subsequent sintering of hydroxyapatite (HAp) nanopowders into the generated structures. For structuring, a novel q-switched CO2 laser with pulse durations of about 600 ns and a peak power of up to 60 kW was used. This laser system provides defined blind holes and channel-like geometries with structural sizes in the range of 100-500 μm. The influence of different process gases (Ar, O2, N2) on the formation of titanium oxide (TiO2) and titanium nitride (TiN) interfaces during laser structuring was investigated by GDEOS. HAp nanopowders prepared by a wet-chemical synthesis route were subsequently sintered into the generated structures using a CO2 laser with continuous radiation intensities up to 2·102 W/cm2. The homogeneously sintered structures consist of HAp as the major phase and minor amounts of tricaliumphosphate (TCP) and tetracalciumphophate (TTCP). The formation of TCP and TTCP during laser sintering can be minimized by adjusting sintering parameters (time, laser intensity) and by applying additional process gases (O2, Ar).
New Titanium Alloys Potentially Used for Metal-Ceramic Applications in Medicine
Authors: Bărbînţă Andreea Carmen , Luca Dorin , Strugaru Sorin Iacob , Biniuc Carmen , Barca Alexandru , Bârcă Eduard , Antoniac Iulian , Munteanu Corneliu
Published: November 2013

Titanium alloys corresponding to Ti-Nb-Zr-Ta system represent a new generation of biomaterials, which were developed for medical applications like metal-ceramic. They are composed of non-toxic and non-allergenic elements and have lower values of modulus of elasticity compared to that of the current biomaterials used in dentistry or orthopedics. In this paper are presented two new titanium alloys (Ti-21Nb-6Zr-15Ta and Ti-25Nb-10Zr-8Ta), which were characterized from structural aspect, mechanical and surface properties point of view using scanning electron microscopy, X-ray diffraction, wear properties, Vickers microhardness measurement. Also, was tested the cytotoxicity of these alloys using direct contact method. The results showed that the investigated alloys have a biphasic structure composed of β-solid solution with intragranular lamellar structures specific to α”. The experimental results shown that new titanium alloys from the system Ti-Nb-Zr-Ta present much better properties compared to that of the metallic biomaterials used currently.
Heat Treatments Influence on Corrosion Behaviour of Some Metallic Biomaterials Potentially Used in Metal-Ceramic Prosthesis
Authors: Ghiban Nicolae , Ghiban Brandusa , Şerban Nicolae , Ghiban Alexandru
Published: November 2013

The present paper put in evidence the influence of applying different heat treatments on some metallic materials such as cobalt and titanium alloys, usualy used for medical applications. The alloys were cobalt base alloy type CoCrMo (22%Cr, 6%Mo, rest Co), in nontreated state, quenching at 1100°C /1h/aer, quenching at 1100°C /1h/air+ sensiblizing at 550°/4h/ air, 600°/4h/air and/or 650°C/4h/air and titanium base alloys - alloy TiMo0.3Ni0,7 (0.23%Mo, 0.72%Ni, Ti rest), alloy TiAl5Fe2V2Mo1,5(1.52%Mo, 5.15%Al, 2.56%Fe, 2.35%V, Ti rest), each of them in non treated state, annealing at 1050°C/1h/air and annealing at 850°C/1h/air. Corrosion tests were made at potentiostat-galvanostat AUTOLAB, in Ringer solution (for both alloys) and NaCl infusion solution (only for cobalt base alloy) by drawing the polarization curves. Our conclusion is that by applying correct and proper heat treatments to both at cobalt alloys and in titanium alloys there is an improving of the corrosion resistance.
Influence of Thermal Treatment on the Roughness, Corrosion Resistance and Wettability of Hydroxyapatite Films Deposited by RF Magnetron Sputtering
Authors: Dinu Mihaela , Kiss Adrian Emil , Parau Anca C. , Braic Viorel , Vitelaru Catalin , Braic Mariana , Pana Iulian , Balaceanu Mihai , Vladescu Alina
Published: November 2013

In this paper we report on the preparation and characterization of hydroxyapatite coatings deposited on Ti6Al4V alloy by magnetron sputtering deposition method. The amorphous deposited coatings were thermal annealed in a flux of dry nitrogen and water vapours at 800 °C for 30 and 120 minutes, in order to investigate the effect of this treatment on surface roughness, corrosion resistance and wettability. The films were characterized by surface profilometry, electrochemical tests and contact angle measurements. After annealing, the hydroxyapatite coatings became crystalline, exhibiting rougher surfaces, higher corrosion resistance and lower contact angles. We have demonstrated that the hydroxyapatite coating annealed at 800°C for 30 minutes represents a good candidate to be used for medical implants, due to its superior corrosion behaviour and good wettability.
Dynamic Mechanical Analysis of Some Ti-Mo Alloys in Correlation with Microstructural Aspects and Surface Properties
Authors: Ghiban Nicolae , Ghiban Brandusa , Şerban Nicolae , Ghiban Alexandru
Published: November 2013

The present paper takes into consideration four titanium alloys from the system Ti-Mo, with different molybdenum contents in order to highlight the mechanical and structural behavior of them. The Dynamic Mechanical Analysis was made and this was in correlation with microstructural aspects and surface properties of the experimental alloys. The macrostructural features are the same for all Ti-Mo alloys after bending tests.
The Biofilm Formation onto Implants and Prosthetic Materials May Be Contrasted Using Gallium (3+)
Authors: Rimondini Lia , Della Valle Cinzia , Cochis Andrea , Azzimonti Barbara , Chiesa Roberto
Published: November 2013

Bacterial contamination of implanted devices is a common cause of their failure. Microbial contamination of the biomaterials differs from that of natural tissues. In fact, the contamination modalities of medical devices depend on many peculiar factors related to them: the chemistry of the biomaterial, the physical properties of the surface, the design of the medical device, the extension of surgical invasion, and the time of application. The environment and/or the conditions and response of the host also contribute to the development of infection. Viruses, fungi, protozoas and bacteria are all involved in biomaterial contamination. They are endogenous commensals of the mouth, not virulent in planktonic form, but pathogens when arranged in biofilm.In this paper we review the potency of application of Gallium doping to the surface biomaterials addressed for surgical implantation in order to contrast the bacteria biofilm formation
Eight-Year Clinical Follow-Up of Sinus Grafts with Micro-Macroporous Biphasic Calcium Phosphate Granules
Authors: Seong Kim Chang , Cho Kim Sung , Daculsi Claire , Seris Elodie , Guy Daculsi
Published: November 2013

Restoring alveolar bone following tooth extraction or pathological diseases is important, and recent efforts have been made to overcome the use of autografts during dental implantation. Although micro-macroporous biphasic calcium phosphate (MBCPTM) has performed well in orthopedic procedures, few studies have investigated its use in dentistry. Here, we report a greater than eight-year clinical follow-up of bone regeneration using MBCPTM after sinus grafting. MBCPTM technology is a unique mixture of hydroxyapatite and β-tricalcium phosphate, which displays both macroporosity and microporosity. A total of 25 patients (33 implantation sites) were evaluated by X-rays, and their pre-operative and immediate post-operative bone heights were measured. After approximately six months, dental implantation was performed. Subsequently, X rays were performed each year, and bone height was measured. In all cases, radio-opacity of the implantation area decreased with time, indicating resorption and bone ingrowth at the expense of the MBCPTM material. After one year, the implantation area had the appearance of physiological bone and <11% of height loss was observed. Strikingly, the newly formed bone was preserved after 78 years of follow-up, with only <14% of height loss recorded. We demonstrate that sinus grafting followed by dental implantation with a resorbable and bioactive synthetic bone graft material (MBCPTM technology) safely and efficiently supports dental implantation.
A Pilot Study Regarding the Biomechanical Behaviour of Endosteal Implants
Authors: Dobreci Cristian , Petre Alexandru , Traistaru Matei
Published: November 2013

An endosteal implant is an alloplastic material surgically inserted into a residual bony ridge primarily as a prosthodontic foundation. Root form implants are the design most often used. Although many names have been applied, the 1988 National Institutes of Health consensus, statement on dental implants and the American Academy of Implant Dentistry recognized the term root form. Misch developed a generic language for endosteal implants in 1992. This language is presented in an order following the chronology of insertion to restoration. In formulating the terminology, five commonly used implant systems in the United States were referenced. Ten years later, the dramatic evolution in the implant market led to reconsideration of the terminology. At the moment, over 3000 different implant systems are on the market, but the comparative evaluation is not done by objective means.
Synthesis of Controlateral Hip Fracture in Osteoporotic Patients – Prophylactic Treatment
Authors: Cristea Stefan , Groseanu A. , Prundeanu A. , Gartonea D. , Dragosloveanu S.
Published: November 2013

the study tried to evaluate the advantages of mini-invasive prophylactic synthesis of controlateral hip fractures in osteoporotic patients. Material and method: 4 patients have been operated between 2009-2010 with hip fractures in osteoporotic patients. Neck fractures Garden IV in 2 patients and pertrochanteric fractures Kyle III and IV in two others patients. The fracture site was operated in dorsal decubitus under spinal anesthesia, we took adventage of this operation and anesthesia to performe a minimal invasive percutaneous synthesis for the nonfracture controlateral side. We used a simple implant, a quickly method during the same surgery time and anesthesia. The K wires with injected cement were percutaneously inserted. Through a 5 mm skin incision, a channel is created in the proximal femur bone and the implant, made of a fabric pouch hosting Titanium rods, is built percutaneously within the femur. A small amount of bone cement is then added, and interdigitates to the osteoporotic bone to further fixate the implant. Results: Rehabilitation was obtained and full weight bearing was allowed immediately. The potential benefits expected with the use of this minimally invasive method are: Quick procedure 15 min, No soft tissue or bone damage, No bleeding, short rehabilitation period, reduced morbidity and mortality, Low cost, same drape, single anesthesia. Conclusions: The method is simple, reproductible and economically. It can be made in emergency by the resident surgeon. The patient will be operated during the same anesthesia after the operation of fractured hip.
Synthesis of Nano Calcium Phosphate via Biomimetic Method for Bone Tissue Engineering Scaffolds and Investigation of its Phase Transformation in Simulated Body Fluid
Authors: Raz Majid , Moztarzadeh F. , Shokrgozar Mohammad A. , Tahriri M.
Published: November 2013

In this study the formation of calcium phosphate phase via double diffusion method into a hydrogel matrix was investigated and its phase transformation in simulated body fluid was studied. White precipitate was formed within the hydrogel, due to the diffusion of calcium and phosphate ions through the hydrogel matrix in similar pH to human body. Phase composition, microstructure and structural groups in the composite samples were also characterized by X-Ray Diffraction (XRD), scanning electron microscopy (SEM) and Fourier transform infra-red (FTIR) analyses. Microstructure of precipitates formed within middle hydrogel, showed that detected materials are composed of carbonated hydroxyapatite and dicalcium phosphate dihydrate (DCPD, brushite). The particle size was about 10 nm .Analysis results showed that after incubation in simulated body fluid, dicalcium phosphate dehydrate phase transformed into crystalline hydroxy apatite.
Numerical Life Estimation of Structure Components Subjected to Hydrogen Embrittlement and Cycling
Authors: Tarakanov Pavel V. , Romanov Aleksander , Shashurin Georgy V.
Published: November 2013

Engineering models to estimate a life of structure components which are simultaneously subjected to aggressive hydrogen environment influence and cycling, substantially, use two different approaches to problem-solving, i.e. the influence of aggressive hydrogen environment on material and the fatigue. A developed engineering model to estimate the life of structure components assumes that either the influence of aggressive hydrogen environment, or the fatigue initiates a local fracture of structure component. The engineering model enables a calculating of a structure component life.
3D Studies of Indentation by Combined X-Ray Tomography and Digital Volume Correlation
Authors: Mostafavi Mahmoud , Vertyagina Yelena , Reinhard Christina , Bradley Robert , Jiang Xia , Galano Marina , Marrow James
Published: November 2013

Hardness testing obtains material properties from small specimens via measurement of load-displacement response to an imposed indentation; it is a surface characterisation technique so, except in optically transparent materials, there is no direct observation of the assumed damage and deformation processes within the material. Three-dimensional digital image correlation (digital volume correlation) is applied to study deformation beneath indentations, mapping the relative displacements between high-resolution synchrotron X-ray computed tomographs (0.9 μm voxel size). Two classes of material are examined: ductile aluminium-silicon carbide composite (Al-SiC) and brittle alumina (Al2O3). The measured displacements for Hertzian indentation in Al-SiC are in good agreement with an elastic-plastic finite element simulation. In alumina, radial cracking is observed beneath a Vickers indentation and the crack opening displacements are measured, in situ under load, for the first time. Potential applications are discussed of this characterization technique, which does not require resolution of microstructural features.
Mass-Velocity Correlation in Impact Fragmentation
Authors: Pál Gergő , Varga Imre , Kun Ferenc
Published: November 2013

We study the impact fragmentation of two-and three-dimensional disordered solids in a discrete element model of heterogeneous brittle materials focusing on the spatial distribution and mass-velocity correlation of fragments. Our calculations revealed that depending on the energy of impact the breakup process can have two different outcomes: at low impact energy the sample gets damaged, however, to achieve fragmentation the imparted energy has to surpass a critical value. Based on large scale computer simulations we show that the position of fragments inside the original body with respect to the impact site determines their mass and velocity in the final state. A novel relation of the mass and velocity of fragments is revealed: In the damage phase the mass and velocity of fragments are strongly correlated, however, in the fragmented phase correlation emerge solely for large fragments. The correlation function decays as a power law with a universal exponent in an excellent agreement with recent experimental findings.
Compression of Heterogeneous Material Systems Based on Wang Tilings
Authors: Doškář Martin , Novák Jan
Published: November 2013

The present study is on the concept of modeling of heterogeneous materials by means of Wang tilings. The central idea is to store a microstructural information within a finite set of Wang Tiles, which allow for reconstructing heterogeneity patterns of random media in planar domains of arbitrary sizes. The particular objective of presented work is our automatic tile set designer in conjunction with stochastic tiling synthesis algorithm. The proposed methodology is demonstrated on different examples. The proximity of synthesized microstructures to reference media is explored by statistical descriptors and discussed in terms of parasitic spatial orientation orders that may occur.
Fracture-Micromechanics Based Model of Mortars Susceptible to Shrinkage
Authors: Nežerka Václav , Tesárek Pavel , Zeman Jan
Published: November 2013

The addition of stiff aggregates into a relatively compliant matrix results, up to a certain limit, in an increase of the effective mortar stiffness. Conventional micromechanical models are not able to capture this limit and must be coupled with a fracture mechanics model predicting the formation of microcracks between aggregates due to shrinkage of matrix. The proposed model utilizes the Mori-Tanaka (MT) scheme together with an estimation of a crack density, based on requirements for the crack formation determined by a numerical analysis. As a result, the model involves a single phenomenological constant, and provides significant improvement over the basic MT scheme.
Temperature Field and Solidification Structure of a Ductile-Cast-Iron Roller
Authors: Kavička František , Dobrovská Jana , Stránský Karel , Sekanina Bohumil , Stetina Josef
Published: November 2013

The quality of the working rollers from ductile-cast-iron used for rolling rails is determined by the chemical and structural composition of the material of the rollers and the production technology. The requirements of the quality cannot be ensured without perfect knowledge of the course of solidification, cooling and heat treatment of the cast rollers as well as the kinetics of the temperature field of the casting and mould. An original application of ANSYS simulated the forming of the temperature field of the entire system comprising the casting, the mold and ambient. In the experimental investigation of temperature field, an original methodology for the measurement of the distribution of temperatures and heat flows in the roller-mould system had been developed and verified in the operation. The kinetics of the solidification has a measurable and non-negligible influence on the chemical and structural heterogeneity of the investigated type of ductile-cast-iron. Tying on to the results of the model of the temperature field of the cast rollers, an original methodology was developed for the measurement of chemical microheterogeneity. The chemical and structural heterogeneity of the cast roller is therefore a significant function of the method of melting, modification and inoculation and the successive procedures of risering, casting and crystallization after cooling.
The Use of Computer Simulation in the Electronic Packaging Process
Authors: Psota Boleslav , Buršík Martin , Szendiuch Ivan
Published: November 2013

This paper deals with the use of the computer simulation for semiconductor chip attach investigation, where the wire bonding is the mostly used process. The main focus lays on the correct definition of the capillary trace, which is essential for creation of a good bond contact as for chip, as well for package or substrate pad. Several simulations for different shapes of loops were created and compared with real bonds, which were done based on the settings from the analysis.
Damage Mechanics and Critical Plane Approach to Multiaxial Fatigue
Authors: Brighenti Roberto , Carpinteri Andrea
Published: November 2013

The mechanical behaviour of structural components subjected to multiaxial fatigue loading is very important in modern design. Several approaches have been introduced in recent decades to analyse this problem. The so-called critical plane approach, based on the stresses acting on the plane where the crack nucleation is expected to occur, is widely used. This criterion can give us a fatigue damage measurement, which can be used to evaluate fatigue life. On the other hand, fatigue life under general multiaxial stress histories can also be assessed by applying the damage accumulation method. In such a method, a scalar damage parameter is quantified through the damage increments which develop during the fatigue process up to the critical damage value corresponding to the final failure of the structures. The damage increment approach to fatigue has recently been discussed and connected to the classical crack propagation approach. In the present paper, the interpretation of the critical plane approach based on the continuum damage mechanics concepts is examined. In particular, the physical meaning of the critical plane approach is shown, that is, such an approach can be interpreted as a damage method which takes into account the scalar damage parameter evaluated along preferential directions. Finally, the fatigue behaviour of a metallic material under multiaxial cyclic load histories is analysed through the two above approaches.
Estimation of the Zone of Failure Extent in Quasi-Brittle Specimens with Different Crack-Tip Constraint Conditions from Stress Field
Authors: Veselý Václav , Sobek Jakub , Frantík Petr , Štafa Michal , Šestáková Lucie , Seitl Stanislav
Published: November 2013

A multi-parameter fracture mechanics concept based on the Williams power series is applied on novel cracked specimen geometries utilizing combined boundary conditions of the wedge splitting and the three-point bending test. Crack tip stress fields for various configurations (causing different constraint conditions at the crack tip and thus also different fracture process zone extents) are numerically investigated and subsequently analytically reconstructed using developed procedure. An importance of using higher order terms of the Williams series is demonstrated.
On the Correlation of Fracture Quantities in Small Punch Test
Authors: Dobeš Ferdinand , Dymáček Petr
Published: November 2013

Several possible routes are available for estimation of fracture behaviour from the results of small punch tests performed at constant rate of deflection. The routes include: (i) measurement of relevant dimensions directly on ruptured specimens, (ii) determination of critical deflections on the load vs. deflection curves and (iii) integration of these curves up to specific points. Equivalent fracture strain, fracture energy or fracture toughness are then evaluated from the obtained quantities. The mutual relations among the quantities are demonstrated by the results of small punch tests performed on a Fe-Al-based alloy in the temperature range extending from brittle up to ductile fracture appearance.
Mixed Mode Interlaminar Fracture of Carbon Nanotubes Enhanced Epoxy/Glass Fiber Composites
Authors: Silva Henrique , Ferreira José A. Martins , Costa José Domingos M. , Capela Carlos
Published: November 2013

Present paper studied the improvement of the fracture toughness under mixed mode loading obtained by using carbon nanotubes reinforcement in fiber glass mats/ epoxy laminates. Mixed-mode bending tests were performed considering different loading ratios GII/GI. Laminates were manufactured using the epoxy resin Biresin® CR120 reinforced with fiber glass triaxial mats ETXT 450 and multiwalled carbon nanotubes with 98% of carbon. It was observed that the total fracture toughness increases linearly with the mode II loading component and that linear mixed-mode fracture criteria reproduces the GI versus GII relationship. The incorporation of small quantity, up to 0.5%, of carbon nanotubes into matrix improves significantly mixed-mode fracture toughness.
Porous Magnesium for Medical Applications - Influence of Powder Size on Mechanical Properties
Authors: Čapek Jaroslav , Vojtěch Dalibor
Published: November 2013

Porous magnesium materials appear to be promising candidates for scaffold production. In this work we prepared porous magnesium samples by powder metallurgy using ammonium bicarbonate as space-holder particles. We focused on the influence of the magnesium powder size and shape on product characteristics. Samples prepared using magnesium chips showed significantly worse flexural properties than samples with similar porosities prepared from an equi-axed magnesium powder. Therefore, we can conclude that spherical particles are more suitable for the preparation of porous objects by powder metallurgy.
Fractographic Analysis of Surface and Failure Mechanisms of Nanotitanium after Laser Shock-Wave Treatment
Authors: Maruschak Pavlo , Menou Abdellah , Czausow Mykola , Mocharskyi Vitaly
Published: November 2013

In this work, the effect of the laser shock-wave treatment on the surface morphology and regularities in failure of nanotitanium is investigated. Based on the data of fractodiagnostics it is established that the shock-wave treatment changes the mechanism of failure from the brittle chipping to the mixed ductile-brittle one by the shear + separation scheme.
Multiscale Heterogeneity of Bone Microporosities and Tissue Scaffolds
Authors: Kochová Petra , Gregor Tomáš , Prosecká Eva , Eberlová Lada , Tonar Zbyněk
Published: November 2013

Our aim was to use stereology to quantify the volume fraction of osteocyte lacunes, volume fraction of large blood vessels, numerical density of osteocyte lacunes, volume of osteocyte lacunae and bone surface in series of micro-CT images representing samples of spongy and compact bone of human tibia. The spongy bone had a smaller volume fraction of osteocyte lacunes, a greater numerical density of bone lacunes, a smaller volume of the lacunes within the same bone volume and a greater bone surface density when compared to the compact bone. Stereology provided us with data on hierarchical organization of bone structural heterogeneity with reasonable time costs.