bluuebunny/crossref_metadata_2025 huggingface dataset:
Study on Mechanical Properties and Phase Morphology of Thermoplastic Polyurethane/Polypropylene Blends Prepared with Vane Extruder
Authors: Liu Wei Feng , Qu Jin Ping , Jia Shi Kui , Zhao Yong Qing
Published: November 2012

Thermoplastic polyurethane (TPU)/polypropylene (PP) blends with different weight ratios were prepared in a novel vane extruder generating global and dynamic elongational flow. The results indicated that the addition of TPU elastomer to PP significantly improved the mechanical properties of the blends. From the SEM micrographs it could be clearly observed dispersed TPU deformed to be fibers by the effect of elongational flow. Meanwhile the results observed from DSC curves revealed apparent partial miscibility of the blends and enhanced crystallization ability of PP due to the influence of elongational flow
Experimental Study on Fatigue Crack Propagation of Glare3-3/2 with Mechanics Properties
Authors: Xie Zong Hong , Zhao Tian Jiao , Wu Rui
Published: November 2012

This study is to investigate the fatigue crack growth behavior of Glare3-3/2 under various stress levels. The Glare3-3/2 specimen consists of three 2024-T3 aluminum alloy sheets and two layers of glass/epoxy composite lamina. Tensile-tensile cyclic fatigue tests were conducted on centrally notched specimen at four stress levels with various maximum values. A digital camera system was used to take photos of the propagating cracks on both sides of the specimen. Image processing software was adopted to accurately measure the length of the cracks on each photo. The test results show that 1) Compared to 2024-T3 aluminum alloy, the fatigue properties of Glare3-3/2 are much better: under the same loading condition with maximum stress level of 120MPa, the crack growth rate of Glare3-3/2 is roughly 5% of the corresponding value of 2024-T3 aluminum alloy, while the fatigue life is 4 times higher than that of 2024-T3 aluminum alloy. 2) The maximum stress level shows strong influence on fatigue crack propagation behavior of Glare3-3/2. The value of steady state crack growth rate increases linearly, while the number of load cycles decreases exponentially, with respect to the maximum stress values used in the fatigue tests.
A Study of the Relationship between China’s Energy Consumption for Environmental Protection and Economic Growth
Authors: Fang Li Ting , Li Kun Ming
Published: November 2012

Based on annual data of GDP and total energy consumption, this paper uses non-parametric additive models to study the linear and nonlinear relationship between China’s energy consumption for environmental protection and economic growth. The empirical results show that the nonlinear effect of growth of energy consumption for environmental protection on economic growth has an "inverted U" shape, this indicates that there exists environmental Kuznets effect of economic growth in China. Some relevant policy suggestions are proposed according to the empirical results finally.
Research on Water Quality and Environmental Protection Based on Environmental Materials and Economic Change Impacts in Guanzhong Area of Weihe River in Recent Three Decades
Authors: Zhang Ya Juan , Qiu Jing , Niu Shan Shan , Zhou Yin Fang
Published: November 2012

Economic development of guanzhong area has produced a series of impact on Weihe River’s water quality, that deteriorated seriously. Environmental pollution indicators conclude ammonia nitrogen, permanganate index, COD. Weihe River water quality was improved significantly through the adjustment of industrial structure, increased investment in environmental protection and policy made to protect the Waihe River. Environmental materials is very beneficial to environment.In recent years, the new environmental material technology what can be promoted in Guanzhong region, which is carrying out the zero-emission technology in heavily-polluted paper industry, it can solve the pollution problems from the source, and it play a significant role in improving the water quality of Weihe River.
Study on On-Road Emission Characteristics of Gasoline Passenger Cars Fueled with Butanol-Gasoline Blends for Environmental Protection
Authors: Lou Di Ming , Wang Yi Jue , Hu Zhi Yuan , Tan Pi Qiang
Published: November 2012

An experimental investigation was conducted using PEMS(portable emissions measurement system) to compare on-road emission characteristics of passenger cars fueled with several butanol-gasoline blends including a 10% and 20% butanol-gasoline blend (by volume) to that of gasoline. It was found that the higher the proportion of butanol blends in gasoline is the lower the emissions of CO, CO2, unburned hydrocarbons exhibited, while the emission level of NOx is just the opposite. Meanwhile, the emissions of gasoline passenger cars are related with both the traffic conditions and the vehicle speed. Thus, using butanol-gasoline blend fuel as well as improving the traffic conditions is important to lower the emissions of cars so that they are useful to environmental protection to a certain degree.
Treatment Dyeing Organic Wastewater by Titanium Dioxide Prepared with Ion Liquids for Environmental Protection
Authors: Yang Jie , Liu Yi Lu , Wu Qi Hua
Published: November 2012

The dyeing wastewater is processed by photoelectric catalytic oxidation with nickel foam electrode of titanium dioxide， which is prepared with ion liquid. The main influence factors including electrode distance, electrolysis voltage, pH and electrolytic time were studied in processing waste. Results show the optimal operating condition is the electrode gap of 1.0 cm, pH value of 4.4, electrolysis voltage of 5.0V and 100 mg∙L-1 dosages of Na2SO4 in 120 minutes electrolysis time under the irradiation of ultraviolet light . The effect of processing the wastewater with catalytic electrolysis can be greatly improved in water cycle system with continuous air, flocculent and activated carbon. Consequently the removal rate of the Chemical Oxygen Demand (COD)is 78.69%, and the decolored rate is 97.02%. The COD of the processed wastewater is within 100.0 mg∙L-1, and meets the first national emission standards. It is expected that the method will have good prospect in protecting the water resources and environment.
Factors Influencing the Reductive Removal of Cr(VI) by Zero-Valent Iron Materials in the Presence of Humic Acid
Authors: Fan Tian En , Weng Cheng Ji , Lin Jian Hao , Yu Xiao Li , Zhang Zhen
Published: November 2012

The reduction of Chromium (VI) by ZVI filings in the presence of HA was carried out during our investigation. The factors such as reaction temperature, initial pH, Fe0 dosage which influencing the reaction were also researched. The results indicated that: 1. High reaction temperature was beneficial to the reaction. At the temperature of 25 oC, the Cr(VI) concentration decreased from 10 mg L-1 to 0.88 mg L-1 after 120 minutes, but at the temperature of 40 oC, the Cr(VI) concentration was reduce to 0.44 mg L-1; 2. Low initial pH was beneficial to the reaction, and the acid condition was beneficial to the reduction of Cr(VI); 3. the change of Fe0 dosage affect the reaction.
Ab Initio Simulations on the Carbonated Apatite Structure
Authors: Ren Fu Zeng , Leng Yang , Lu Xiong
Published: November 2012

ab initio simulations were employed to investigate the crystal structure of carbonated apatite (CAp). Two possible sites for the carbonate ions in the apatite lattice were considered: carbonate substituting for OH- ion (type-A) and for PO43- ion (type-B). A combined type-AB substitution was also proposed and numerous possible charge compensation mechanisms were treated. The results show that the most stable type-A CAp had its carbonate triangular plane almost parallel to c-axis, making an angle of about 2° at z = 0.46. In the most stable type-B CAp structure, the nearest Ca (2) ion was replaced by a sodium ion and the carbonate group was lying almost flat in b/c-plane. Of all the models considered, mixed substitution type-AB where two carbonate ions replacing one phosphate group and one hydroxyl group shows the most stable structure.
Comparative Study on Bioresorbability of Chelate-Setting Cements with Various Calcium-Phosphate Phase Using Rabbit Model
Authors: Konishi Toshiisa , Takahashi Shuhei , Mizumoto Minori , Honda Michiyo , Kida Koki , Horiguchi Yukiko , Oribe Kazuya , Ishii Ken , Morisue Hikaru , Toyama Yoshiaki , Matsumoto Morio , Aizawa Mamoru
Published: November 2012

We have developed novel calcium-phosphate cements (CPCs) based on the chelate-setting mechanism of inositol phosphate (IP6) using hydroxyapatite (HAp), β-tricalcium phosphate (β-TCP) and α-TCP as starting materials. These cements (IP6-HAp, IP6-β-TCP and IP6-α-TCP cements) have different bioresorbability due to the chemical composition of starting materials. In the present study, biocompatibility and bioresorbability of the above three cements and commercially available cement (Biopex®-R) was histologically evaluated in vivo using rabbit model for 4, 8, and 24 weeks, in addition to their dissolution in vitro. The dissolution of these cements increased in the order of IP6-HAp, IP6-β-TCP and IP6-α-TCP cements. The newly-formed bones were directly in contact with both the IP6-HAp and Biopex®-R cement specimens. As for the IP6-β-TCP and IP6-α-TCP cements, newly-formed bones were formed time-dependently slightly apart from the cement specimens. Resorption rate for Biopex®-R, IP6-HAp, IP6-β-TCP, and IP6-α-TCP cements after 24 weeks implantation were of 7.2, 5.0, 13.7, and 16.2%, respectively, compared to original cements. The present chelate-setting cements with different bioresorbability are promising candidates for application as the novel CPCs.
Smart Calcium Phosphate Bioceramic Scaffold for Bone Tissue Engineering
Authors: Daculsi Guy , Miramond Thomas , Borget Pascal , Baroth Serge
Published: November 2012

The development of CaP ceramics involved a better control of the process of resorption and bone substitution. Micro Macroporous Biphasic CaP, (MBCP+) is a concept based on an optimum balance of the more stable phase of HA and more soluble TCP. The material is soluble and gradually dissolves in the body, seeding new bone formation as it releases Ca and P ions into the biological medium. The MBCP+ is selected for tissue engineering in a large European research program on osteoinduction and mesenchymal stem cell technology (REBORNE 7th EU frame work program, Regenerative Bone defects using New biomedical Engineering approaches, www.reborne.org). We have optimized the matrices in terms of their physical, chemical, and crystal properties, to improve cell colonization and to increase kinetic bone ingrowth. The fast cell colonization and resorption of the material are associated to the interconnected macropores structure which enhances the resorption bone substitution process. The micropore content involves biological fluid diffusion and suitable adsorption surfaces for circulating growth factors. The bioceramics developed for this project was fully characterized using X-Ray diffraction, FTIR, X-rays micro tomography, Hg porosimetry, BET specific surface area, compressive mechanical test, and SEM. Preclinical tests on the optimized scaffold were realized in critical size defects in several sites of implantation and animals (rats, rabbits, goats, dogs).The smart scaffold has a total porosity of 73%, constituted of macropores (>100µm), mesopores of 10 to 100µm and high micropores (<10µm) content of more or less 40%. The crystal size is <0.5 to 1 µm and the specific surface area was around 6m2/g. The in vivo experiment indicated higher colonization by osteogenic cells demonstrating suitable matrices for tissue engineering. The HA/TCP ratio of 20/80 was also more efficient for combination with total bone marrow or stem cell cultivation and expansion before to be implanted.
Preparation of Carbonate Apatite Cement Based on α-TCP
Authors: Matsuya Shigeki , Maruta Michito , Tsuru Kanji , Kunio Ishikawa
Published: November 2012

Carbonate apatite showed an excellent bioresorbability through the remodeling process of bone. In the present study, we prepared self-setting carbonate apatite cement based on α-TCP. We tried two types of the cement powder formulations, that is, first one (F1) is α-TCP containing given amounts (10 to 50 mass%) of synthesized carbonate apatite and second one (F2) is α-TCP treated in 0.5M NaHCO3 for various times between 90 and 360 min. The cement powder was mixed with 0.25M Na2HPO4 to allow set at 37°C and 100% of relative humidity up to 1 day. XRD and FT-IR results showed formation of B-type carbonate apatite phase after setting in both of the formulations. With the formulation, F1, the carbonate content was increased with the treatment time and the maximum content was 4.1 mass%. DTS deacreased with the amount of cabonate apatite in the formulation, F1, however, it increased up to 9 MPa with treatment time in the formulation, F2.
Hydroxyapatite and YSZ Reinforced Hydroxyapatite Coatings by Gas Tunnel Type Plasma Spraying
Authors: Kobayashi Akira , Subramanian B.
Published: November 2012

Chemical structure of hydroxyapatite (HA) is very close to human bone which makes it compatible with the tissue of the human body. Its good biocompatibility makes it to be used extensively in many prosthetic applications, especially as a porous material for optimal bone in growth. Currently, this material is being deposited on bio-inert metallic implants and used as recovery parts in human body. In this present study a high-power plasma jet known as gas tunnel type plasma torch (GTTP), was used to produce HA and YSZ reinforced HA coatings on stainless steel substrate. In this study, microstructure, tribological properties and bioactivity of the GTTP sprayed HA and YSZ reinforced HA coatings was investigated. The XRD spectra of the as-sprayed coatings showed that the as-sprayed pure HA coating retained its crystalline HA phase similar to the initial feed stock HA powder, even though there existed a possibility for occurrence of decomposition during its in-flight in high temperature plasma zone. In the present case the decomposition processes of in-flight HA could be well controlled by means of selective operating parameters and unique nature of GTTP jet. The presence of un-melted particles and pores inside the coating microstructure play a vital role in the bonding strength of the coating.
Bio-Fabrication of Nacre on Conventional Implant Materials
Authors: Kwan Millie , Wang Ri Zhi
Published: November 2012

Nacreous coatings on orthopedic implants can be advantageous because of its robust mechanical properties, high biocompatibility, and ability to promote bone growth. The biofabrication of nacreous coatings on conventional orthopedic implant materials via biomineralization process from abalone shells was examined. The objective was to investigate the effect of different materials on nacreous coating growth. The coatings were characterized by SEM/EDS and XRD. It was found that different materials resulted in different surface morphologies and coating thicknesses, although the main mineral formed was aragonite. Calcium carbonate coating was formed on the entire surface of the poly (methyl methacrylate) and high density polyethylene implants and resulted in a thick coating, while the titanium implants showed thinner coating at the same growing period.
Bioactive Glass Cloth that Promotes New Bone Formation
Authors: Minatoya Tsutomu , Furusawa Toshitake , Sato Masaaki , Matsushima Yuta , Unuma Hidero
Published: November 2012

A new composition of bioactive glass was proposed that can be drawn into fibers, woven into cloth, and has appropriate alkali-releasing ability for bioactivity. The glass was drawn into fibers and woven into cloth, then the biological efficacy of the cloth was examined in in vivo tests. Bone defects made in tibial bones of Wistar rats were covered with the cloth just like "bandage" for two weeks. The cloth was found to promote new bone formation in the bone defects without causing any adverse effects. In contrast, excessive infection was recognized and new bone was not formed when cloth made of E-glass fibers was used. This was the first successful demonstration that glass cloth made of bioactive glass fibers assisted bone regeneration. The present glass cloth, therefore, is expected to be a promising material for "bone bandage" or porous scaffolds for bone tissue regeneration.
Bone Regenerative Properties of Injectable Calcium Phosphate/PLGA Cement in an Alveolar Bone Defect
Authors: Lanao R.P. Félix , Hoekstra J.W.M. , Wolke Joop G.C. , Leeuwenburgh Sander C.G. , Plachokova A.S. , Boerman O.C. , van den Beucken Jeroen J.J.P. , Jansen John A.
Published: November 2012

Periodontitis is one of the most common inflammatory diseases, which can lead to early tooth loss. The conventional treatment of periodontitis is to arrest the disease progression. Most reconstructive procedures involve application of bone substitutes, barrier membranes or a combination of both into the bony defects. Calcium phosphate cements (CPCs) are the predominant type of bone substitute material used for reasons of injectability and hence perfect filling potential for bone defects. Recently, injectable apatitic CPCs demonstrated to be more rapidly degradable when combined with poly (lactic-co-glycolic) acid (PLGA) microspheres. Further, PLGA microspheres can be used as a delivery vehicle for growth factors. In this study, the performance of injectable CPCs as a bone substitute material for alveolar bone defects created in Beagle dogs was evaluated. Four CPC-formulations were generated by incorporating hollow or dense PLGA microspheres, either or not loaded with the growth factors (platelet derived growth factor (PDGF) and insulin-like growth factor (IGF). Implantation period was 8 weeks. Bone formation was based on histological and histomorphometrical evaluation. The results demonstrated that filling alveolar bone defects with CPC-dense PLGA revealed significant more bone formation compared to CPC-hollow PLGA either or not loaded with IGF and PDGF. In summary, we conclude that injectable CPC-dense PLGA composites proved to be the most suitable material for a potential use as off the shelf material due to its good biocompatibility, enhanced degradability and subsequent bone formation.
Histological Analysis of Bone Bonding and Ingrowth into Connected Porous Hydroxyapatite Spacers in Spinal Surgery
Authors: Funayama Toru , Noguchi Hiroshi , Tsukanishi Toshinori , Sakane Masataka
Published: November 2012

To evaluate the osteoconductive potential of connected porous hydroxyapatite (HAp), we histologically analyzed the newly formed bone inside unidirectional porous HAp (Regenos®, Kuraray, Japan; 75% porosity, n=17) and interconnected porous HAp (Neobone®, Covalent Materials, Japan; 75% porosity, n=10) 26 weeks after their implantation as bone spacers between the split lumbar laminae of goats. As a control, non-connected porous HAp spacers (Apaceram®, Pentax, Japan; 50% porosity, n=5) were used. After staining non-decalcified samples with Villanueva Goldner, changes in pore shape were evaluated microscopically and new bone formation in HAp spacers was quantitatively analyzed. In addition, blood vessel distribution was evaluated by hematoxylin and eosin staining. Changes in pore shape were observed in 76% of the Regenos® spacers and 90% of the Neobone® spacers but were not detected in the Apaceram® spacers. Only limited new bone formation was observed in the Regenos® and Neobone® spacers, whereas vascular-like structures were detected in 82% of the Regenos®, 70% of the Neobone®, and 80% of the Apaceram® spacers. The changes in pore shape were thought to have resulted from the low initial compression strength of the connected porous HAp, which may have limited the inherent osteoconductive potential of connected HAp. Our findings suggest that the maintenance of pore shape is required for promoting new bone formation in connected porous HAp when used as lamina spacers in spinal surgery.
Radiological and Histological Evaluation of Regenos® which Implanted in Human Radial Fracture: A Clinical Case Report
Authors: Iwasashi Masashi , Muramatsu Toshiki , Sakane Masataka
Published: November 2012

Regenos® is a unidirectional porous hydroxyapatite (UDPHAp) bone substitutes, and the most distinctive feature of UDPHAp is its interconnected porous structure. We used Regenos® for the bone defect while distal radius fracture surgery with metal fixation implant. At six months post-operation, CT scans revealed the Regenos® implant was uniformly composed of cortical bone adjacent to the trabecular bone. At one-year postoperatively, we collected a sample of the implanted Regenos® while metal fixation plate removal surgery for histological evaluation. Regenos® implant sample revealed the presence of ossified bone stained green with Villanueva Goldner stain. Our findings demonstrate that Regenos® is a useful bone substitution material in the clinical setting.
Changes in Bone Quality of the Femoral Diaphysis Induced by High-Level Fluorine Ingestion in Ovariectomized Rats
Authors: Nakada Hiroshi , Sakae Toshiro , Teranishi Mari , Kato Takao , Watanabe Takehiro , Takahashi Takahiro , Kawai Yasuhiko , LeGeros Racquel Z.
Published: November 2012

Ovariectomized rats were fed a diet containing minerals at high concentrations, such as Ca, P, and F (high-mineral diet), and changes in the femoral diaphysis were investigated after 24 weeks. The femur was mainly red and partially orange on the color scale of the 3D-map in Groups A and B, showing a high BMD. The region adjacent to the marrow cavity was yellow, showing a lower BMD than that in the outer region of the femur. In Group C, the red area was small in the outer region and the inner region was mainly yellow and green on the color scale. The inner region adjacent to the marrow cavity showed a view of unevenly resorbed bone, and the BMD was lower than those in Groups A and B. Incorporation of F into the body influences the apatite crystal structure and crystal growth, which subsequently influences adsorption of F to crystals and structural changes. Therefore, it is important to ingest F at the optimum concentration.
Physico-Chemical Characterization and In Vitro Biological Evaluation of Pure SiHA for Bone Tissue Engineering Application
Authors: Marchat David , Bouët Guénaëlle , Lueckgen Aline , Zymelka Maria , Malaval Luc , Szenknect Stéphanie , Dacheux Nicolas , Bernache-Assollant Didier , Chevalier Jérôme
Published: November 2012

Studies about silicon-substituted hydroxyapatites exhibit several shortcomings that leave unanswered questions regarding the properties and subsequent biological outcomes generated by this biomaterial. Firstly, samples characterization is often incomplete, meaning that phase purity on the pellet surface is not assured. In fact, ceramic materials used in literature that are claimed to be pure are actually polluted through second phase as superficial polymerized silicate. In this study, we have successfully synthesized a phase pure silicon hydroxyapatite powder Ca10(PO4)5.5(SiO4)0.5(OH)1.5 (Si0.5HA) compressed this powder into pellets, sintered them, and evaluated the biological response of osteoblast cells (C3H10 line) seeded on the pellet surface. Besides, the solubility in aqueous media of HA and Si0.5HA pellets were determined through static experiments. These tests attempt to provide a comprehensive picture of the cellular response to the SiHA material, in order to determine the mechanism by which Si evokes the improved in vitro biological outcomes described in the literature. Results revealed first an equivalent solubility of Si0.5HA and HA pellets, and second that cells do not react favourably to the pure SiHA surface.
Three-Dimensional Culture of Vascular Endothelial Cells Using Vascular Endothelial Growth Factor-Loaded Apatite-Fiber Scaffolds with Enhanced Mechanical Property
Authors: Kayashima K. , Oyama R. , Emoto M. , Maehashi H. , Matsuura Tomokazu , Aizawa Mamoru
Published: November 2012

We have successfully developed the apatite-fiber scaffold (AFS) with enhanced mechanical porosity for tissue engineering of bone and liver via two routes: i) use of two type of carbon beads with diameter of ~150 μm and ~20 μm and following ii) uniaxial pressing of the green compacts. Our Aim is to add vascular formation ability into the above AFS in order to maintain the regenerated tissues for a long time. In the present study, the AFSs with various porosities (68±2.4, 85±1.5, 89±0.6, 92±1.0%) were fabricated, and then loaded with vascular endothelial growth factor (VEGF). Drug release from VEGF-loaded AFSs with various porosities was examined by immersing them into phosphate buffer. The AFSs with the highest porosity (92%) could be released with the most VEGF among examined AFSs. In addition, we carried out preliminary study for the compatibility of vascular endothelial cells, M1 cells established by Matsuura et al. to the VEGF-loaded AFS (porosity: 92%), in order to account for the vascular formation into the pore of the AFS. The numbers of M1 cells cultured in/on the VEGF-loaded AFS were about 1.5 times that of VEGF-free AFS over a period of cell culture. These results demonstrate that the VEGF-loaded AFS with enhanced mechanical property have a good compatibility to the M1 cells as a model of vascular endothelial cells.
Expression of Integrin Alpha-3 and Beta-4 Subunits on the Process of Peri-Implant Epithelium Formation
Authors: Atsuta Ikiru , Ayukawa Yasunori , Yamaza Takayoshi , Furuhashi Akihiro , Kondo Ryosuke , Koyano Kiyoshi
Published: November 2012

Integrin, a component of the hemidesmosome, plays a role for epithelial cell migration and adhesion. This study investigated the process of peri-implant epithelium (PIE) formation after implantation, and compared it to the process of oral mucosa healing after tooth extraction. At the healing site of extraction socket without implant, the original junctional epithelium (JE) had disappeared at week 2, and the oral epithelium (OE) with integrin-α3 positive basal cells extending from the sides of the wound, then joined in the middle of the extraction socket. On the other hand in implant group, newly formed epithelium with integrin-α3 positive cells from the OE extended apically 1 week after implantation. After 3 weeks, basal cells of the new epithelium consisted of those with integrin-α3 positive but β4 negative. Finally, after 4 weeks, integrin-β4 was expressed at the implant-PIE interface. These findings suggest that integrin α3β1 plays a role in cell migration during PIE formation from OE. Furthermore, after the completion of PIE constitution, integrin α6β4 contributes to the attachment to titanium.
Comparison of PLGA Reinforcement Method for Carbonate Apatite Foam
Authors: Munar Girlie M. , Munar Melvin L. , Tsuru Kanji , Kunio Ishikawa
Published: November 2012

Carbonate apatite (CO3Ap) foam with interconnecting porous structure is a potential candidate as bone substitute material owing to its similarity to the cancellous bone with respect to composition, morphology and osteoclastic degradation. However, it is brittle and difficult to handle. This is thought to be caused by no organic material in the CO3Ap foam. The aim of this study is to reinforce the CO3Ap foam with poly (DL-lactide-co-glycolide) (PLGA). Immersion and vacuum infiltration methods were compared as reinforcing methods. Compressive strength of unreinforced CO3Ap foam, (12.0 ± 4.9 kPa) increased after PLGA reinforcement by immersion (187.6 ± 57.6 kPa) or by vacuum infiltration (407 ± 111.4 kPa). Scanning electron microscopy (SEM) showed the preservation of full interconnecting porous structure of CO3Ap foam after PLGA reinforcement using immersion or vacuum infiltration. Interface between the PLGA and CO3Ap foam, however revealed that no gap was found between the PLGA and CO3Ap foam interface when vacuum was used to reinforce the PLGA whereas a gap was found when simple immersion was used. Strong interface between PLGA and CO3Ap foam is therefore thought to be the key for higher compressive strength. In conclusion, vacuum infiltration is a more efficient method to reinforce the CO3Ap foam with PLGA for improving the mechanical strength without sacrificing the cancellous bone-type morphology.
Rare Earth Oxide Containing Filler for Dental Composite Resin
Authors: Uo Motohiro , Nakajima Yasuo , Asakawa Yuya , Wada Takahiro , Hongo Toshio , Soga Kohei , Kogo Yasuo
Published: November 2012

A composite resin (CR) with photo-polymerization is widely used for dental filling material. Because of their good esthetics, the visual inspection of restored teeth becomes difficult. In this study, the fluorescent glass/ceramics fillers containing rare earth oxides — which are well-known fluorescent materials — was prepared and applied in CR to enhance visual inspection capability with small influence in color. Eu2O3-containing Y2O3 filler (Y2O3:Eu) prepared with homogeneous coprecipitaion method showed clear fluorescence at 614nm with near ultraviolet light (385nm) excitation. The fluorescence intensity of the prepared Y2O3:Eu filler increased with increase of Eu content in the Y2O3 filler upto 15mol% of Eu content. The composite resin was prepared with the mixed filler of Y2O3:Eu filler and the conventional glass filler. The content of Y2O3:Eu was varied between 0 to 40wt% of mixed filler. The prepared composite resin also showed clear fluorescence with quite small affect to the color change and the Vickers hardness of composite resin. Therefore, the prepared rare earth oxide containing Y2O3 filler was applicable as the filler of dental composite resin.
Effect of Anions on Morphology Control of Brushite Particles
Authors: Hamai Ryo , Toshima Takeshi , Tafu Masamoto , Masutani Takaaki , Chohji Tetsuji
Published: November 2012

Brushite (DCPD, CaHPO4·2H2O) crystals are of great significance in a range of fields including biology, medicine, chemistry, and materials science. One important issue is the control of their morphology; when the crystal growth conditions are changed, the morphology and surface crystal conditions also change. The chemical reaction behavior depends strongly on the surface condition of the particles. Here, we report the effect of coexisting anions on the morphology control of DCPD particles. We synthesized the particles through a liquid-phase reaction by mixing a starting solution of ammonium dihydrogen phosphate (NH4H2PO4) and calcium salts. Calcium nitrate (Ca (NO3)2) and calcium acetate (Ca (CH3COO)2) were used as the calcium sources to clarify the pH dependence of the morphology. We mixed the solutions with the same pH values and agitated them, and observed the products by scanning electron microscopy (SEM) and X-ray diffraction (XRD); the DCPD morphology varies from petal-like to parallelogram structures depending on the initial pH value of the solution and the combination of the starting mixture. The effect of the acetic acid anion is to increase the driving force for the generation of DCPD crystal nuclei.
Influence of Titanium Surface Topography on Peri-Implant Soft Tissue Integration
Authors: Furuhashi Akihiro , Ayukawa Yasunori , Atsuta Ikiru , Rakhmatia Yunia Dwi , Yasunami Noriyuki , Koyano Kiyoshi
Published: November 2012

At the neck area of dental implant surface, machined surface (Ms) has been employed to avoid surface contamination. Recently, implants which have roughened surface texture (Rs) at their neck are also available. However, from the viewpoint of soft tissue integration, it remains to be elucidated whether or not surface topography affects the soft tissue attachment around implants. The aim of the present study was to clarify the influence of surface topography on peri-implant soft tissue integration. First, surface roughness of both surfaces was measured. Second, protein adsorption capability on both surfaces was examined. Then, as the rat implant model, titanium implants with each surface were inserted into the maxillae. Horseradish peroxidase (HRP) tracer was applied 4 weeks post implantation to the gingival sulci of implants or natural teeth (NT) to investigate the sealing capability of periodontal/peri-implant soft tissue. Collagen density was also observed by fluorescent staining. As a result, surface roughness (Sa) of Ms and Rs was 0.16 µm and 0.25 µm, respectively. Protein adsorption capability on both surface showed no significant differences. In the NT group of the rat implant model, presence of HRP was restricted only in the coronal portion of epithelium. In both implant groups, in contrast, more invasion of HRP was observed in the soft tissue around implants. Especially in the Ms group, more HRP was observed in the deeper area compared with Rs group. Stronger expression of collagen was observed around Rs compared to Ms at the connective tissue-implant interface. It could be speculated that, with dense collagen, Rs implants showed stronger soft tissue integration compared with Ms implants, but the integration is not as strong as NT’s.
Titanium and Ti-13Nb-13Zr Alloy Porous Implants Obtained by Space-Holder Technique with Addition of Albumin
Authors: Goia Tamiye Simone , Violin Kalan Bastos , Bressiani José Carlos , Bressiani Ana Helena de Almeida
Published: November 2012

Titanium and its alloys are the main metals studied as porous metallic implants by their excellent mechanical properties and biological interactions. Production methods of porous metallic materials are based on powder metallurgy (PM), because it allows the manufacturing of parts with complex shapes and dimensions close to the finals (near-net shape), and the addition of alloying elements reaching a satisfactory structural homogeneity, and porosity. The pore production by space-holder technique constitutes of mixing organic compounds with metal powder, which when removed by thermal treatment prior structures are kept in place. The objective of this study is to obtain porous implants of commercially pure titanium (cpTi) and Ti-13Nb-13Zr alloy by PM with space-holder technique and albumin as an additive. For the processing of the samples were used hydride titanium powder (TiH2) to obtain cpTi samples, and metal powders of Ti, Nb and Zr in the stoichiometric proportions for obtaining the alloy samples. The samples were prepared by mixing the metallic powder to the albumin (30wt%) and filling a silicone model that was pressed isostatically (140 MPa). The thermal treatment was performed in an oxidizing atmosphere (350°C/1h) for the decomposition of organic material. The sintering was performed at a temperature of 1300°C (1h/cpTi, 3h/Alloy) in high vacuum furnace (10-5 mBar) to all samples. The calculated porosity showed a significant difference between the samples cpTi (40%) and alloy (60%). The samples surface characterization showed very rough with high specific surface area. Samples of cpTi presented formation of necks arising from sintering. In the alloy samples were observed homogenous microstructure with the presence of α and β phases composing the Widmanstätten structure. It is possible to conclude that the same amount albumin allowed the formation of pores in the microstructure of cpTi and alloy although in different proportions, without harming the sintering of both and allowing diffusion of the alloy elements.
Adsorption Behavior of Albumin and other Proteins on Carbon Nanotubes Studied by Chromatography
Authors: Morikawa M. , Kuboki Y. , Akasaka Tsukasa , Abe Shigeaki , Takita H. , Watari Fumio
Published: November 2012

For application of carbon nanotubes (CNTs) as biomaterials, it is important to clarify the interaction between CNTs and proteins, which may affect on cell proliferation and differentiation. In this study, the adsorption behavior was investigated for representative proteins, bovine serum albumin, lysozyme and fetal bovine serum by using chromatography system. It was also aimed whether the different treatment conditions of CNTs affected the adsorption of proteins. CNTs used for this study had a straight shape and about 70nm in a diameter from SEM observation. There was not much difference between untreated and treated CNTs from SEM images. In chromatography experiments, all the proteins of albumin, lysozyme and serum were eluted immediately after injected to the column of untreated CNTs. Second elution appeared after buffer was changed from phosphate saline buffer to 25mM sodium hydroxide (NaOH). The same tendency was confirmed for CNTs with only acid treatment. However the eluted peaks became remarkably smaller after the column was changed to CNTs with thermal and twice acid treatments. These results indicated that treatment conditions for CNTs affected the adsorption behavior of proteins.
Cytotoxicity and Cancer Detection Ability of the Luminescent Nanoporous Silica Spheres Immobilized with Folic Acid Derivative
Authors: Tagaya Motohiro , Hanagata Nobutaka , Ikoma Toshiyuki , Kobayashi Takaomi , Shiba Kota , Yoshioka Tomohiko , Tnaka Junzo
Published: November 2012

Luminescent europium(III)-doped nanoporous silica spheres (Eu:NPS) were synthesized, and folic acid derivative (FA: folate N-hydroxysuccinimidyl ester) as targeting ligand for cancer cells was immobilized on the sphere through a mediation of 3-aminopropyltriethoxysilane (APTES). The ordered nanopores were preserved with the immobilization. The surface area decreased only with the APTES immobilization, suggesting that the FA was immobilized only on the outer surface of the nanopores. The photoluminescence of the spheres showed the characteristic peak due to interactions between the FA and Eu3+, and further the luminescence can be clearly detected by a fluorescent microscopy. The spheres were highly dispersed stability in cell culture medium to exhibit the nontoxic in the proliferation stage of Hela cancer cells and NIH3T3 fibroblasts, and specifically bindto the Hela cells. The binding and uptake spheres showed the intense luminescence. Thus, the luminescent FA-immobilized Eu:NPS spheres will exhibit the targeting and imaging abilities for cancer cells.
Sol-Gel Preparation of HAp-Coated Silica Macrospheres from Water Glass and their Protein Adsorption
Authors: Li Jie , Shirosaki Yuki , Hayakawa Satoshi , Stamboulis Artemis , Osaka Akiyoshi
Published: November 2012

Silica gel macrospheres of 2~4 mm in size, and wrapped with Ca-alginate chelate film were prepared as the substrate for hydroxyapatite coating layer, using water glass as the silica source. Those Ca-SiO2 macrospheres were soaked in a 1:1 (volume) mixture of ethanol and 0.1 M Na2HPO4 to deposit hydroxyapatite layer (HAp-SiO2 macrospheres). Adsorption of bovine serum albumin and egg lysozyme on those Ca-SiO2 and HAp-SiO2 macrospheres under physiological pH (7.2) was well correlated to the Langmuir-type adsorption equation. The electrostatic interactions between the protein molecules and those macrospheres well interpret the adsorption isotherms, while the mesopores in the Ca-SiO2 contributed to some extent. A multi-layer adsorption model was proposed.
Orientation of Hydroxyapatite Rods Formed by Hydrothermal Treatment of Calcium Carbonate
Authors: Kim Ill Yong , Kikuta Koichi , Ohtsuki Chikara
Published: November 2012

Morphological control on hydroxyapatite (HAp) crystals is one of attractive researches to produce novel bioactive materials for repairing bone defects. Hydrothermal processing has been applied to fabricate well-grown crystals of HAp, through a reaction from appropriate calcium and phosphate sources. We recently found that oriented structure was observed when single crystal of calcium carbonate was used as a starting material for the hydrothermal processing. However, the detailed process on the orientation of HAp crystals has been not clarified yet. In the present study, we investigated the effects of the crystalline planes of calcite on HAp formation through the hydrothermal condition. Calcite single crystals with either of {100} or (111) plane was used as a starting material to examine the difference of the reactivity in a phosphate solution. After the hydrothermal treatment at 160 °C for 24 h, the surfaces and cross-sections of starting materials were characterized. Rod-shaped HAp crystals were oriented on the surface of the starting material with {100} plane, whereas small HAp crystals formed on the starting material with (111) plane followed by growth to same direction that were observed on the sample with the {100} plane. The difference in the morphology of the formed HAp was caused by the reactivity of each crystal plane.
Heterogeneous Structure of Hydroxyapatite and In Vitro Biodegradability
Authors: Hayakawa Satoshi , Shirosaki Yuki , Osaka Akiyoshi , Jäger Christian
Published: November 2012

Hydroxyapatite (HAp) particles were synthesized by solid-state reaction and wet chemical reaction, and were characterized in terms of their chemical composition, disordered structure and in vitro biodegradability. An X-ray diffraction study revealed that the prepared HAp particles were composed of single phase HAp, while 1D and 2D solid-state NMR analysis showed that they consisted of not only crystalline HAp but also a disordered phase. An in vitro biodegradability test showed that wet chemically derived HAp particles were degraded quicker than commercially available HAP-100. The in vitro biodegradability was discussed by using a structure model for nanocrystalline HAp, in which the nanocrystals consist of a crystalline HAp core covered with a disordered surface layer (core-shell model). Although the specific surface area was the predominant factor on the rate of Ca ion dissolution, the disordered surface layer enhanced the release of Ca ions in the initial stage within 1 min, while the crystalline core of HAp also gave different release rate of Ca ions, depending on the chemical distribution in the P (V) environment.
Enhanced Effects of New Bone Formation by an Electrically Polarized Hydroxyapatite Microgranule/Platelet-Rich Plasma Composite Gel
Authors: Ohba Seiko , Wang Wei , Itoh Soichiro , Nagai Akiko , Yamashita Kimihiro
Published: November 2012

The effects of electrically polarized HA microgranule/PRP compositeon new bone formation were examined. The composite gel was implanted into bone holes in rabbits. Histological examination was performed 3 and 6 weeks post-surgery. It was hypothesized that PRP alone could not induce new bone formation until 6 weeks after implantation. HA microgranules with or without electrical polarization/PRP composite, especially the former, activated osteogenic cells, resulting in enhanced bone formation. It was confirmed that electrical polarization treatment of HA microgranules can accelerate new bone formation and this effect is enhanced by forming a complex within PRP.
Positron Irradiation Effects in HDPE during PAL Measurement at Ambient Temperature
Authors: Kansy Jerzy , Ziąbka Magdalena
Published: November 2012

The positron irradiation effect in high density polyethylene at ambient temperature is studied by positron annihilation lifetime method. The positron spectra are analyzed with a model which takes into account positron trapping and so called delayed formation of positronium (DFP). A good relationship is noticed between the rate of positron trapping and the rate of DFP.
Positron Lifetimes and Mechanical Properties of Gamma-Irradiated Ultra High Molecular Weight Polyethylene
Authors: Kobayashi Yoshinori , Yamawaki Masato , Oka Toshitaka , Saiki Seiichi , Mohamed Hamdy F.M. , Hattori Kanehisa , Watanabe Yoshihiro
Published: November 2012

Positron annihilation lifetime spectroscopy (PALS) has widely been used for probing open volume defects in various materials. PALS is in principle non-destructive, yet conventional PALS is not strictly non-destructive because cutting out of two specimens from the material is required. Recently we developed a novel method of PALS, which is potentially applicable to non-destructive, onsite material inspection. In order to explore the possibility of onsite monitoring of polymer degradation by this novel method of PALS, we studied variations of positron lifetime and mechanical properties of ultra high molecular weight polyethylene (UHMWPE) subjected to γ-irradiation. Correlations were found between the mechanical properties and ortho-positronium lifetimes, suggesting the feasibility of non-destructive, onsite monitoring of polymer degradation by PALS. The effect of γ-irradiation on positronium formation is discussed.
Effects of Local Heating and Premelting in the Terminal Part of the e+ Track
Authors: Zvezhinskiy Dmitry , Stepanov Sergey V. , Byakov Vsevolod , Zgardzińska Bożena
Published: November 2012

The terminal part of the e+ track (the positron blob) is formed during ionization slowing down and subsequent ion-electron recombinations produced by a positron. It releases up to 1 keV of energy, which is converted into heat within few picoseconds. If a bulk temperature of a medium is below, but close enough to its melting point, some region of a substance may melt, yielding a peculiar temperature dependence of the lifetime (LT) spectra. We have estimated properties of the molten region with a help of macroscopic heat con- duction equation and suggested a model describing temperature dependence of the ortho- positronium lifetime in frozen methanol, ethanol, butanol and water close to their melting points.
Effect of Crosslinkers on the Microstructure and Swelling Properties of the N-Isopropyl Acrylamide Gels: A Positron Annihilation Study
Authors: Patil Pushkar N. , Sudarshan Kathi , Pujari Pradeep K. , Dutta Dhanadeep
Published: November 2012

The Poly N-Isopropyl acrylamide (PNIPA) gels were prepared in different synthesis media by crosslinking with acrylate monomers with varying chain length. The microstructural characterization in terms of the free volume fractions and distributions were studied using positron annihilation lifetime spectroscopy (PALS). The equilibrium swelling of the PNIPA in distilled water was measured. An attempt has been made to understand the correlations between microscopic free volumes and the equilibrium swelling of the gels. The free volume fraction of the gels prepared in Dimethyl formamide (DMF) was directly correlated with swelling while it varied inversely with chain length of the crosslinker. The microstructure of the gels was found to be very sensitive to the solvent/medium used for polymerization. Our studies show that the swelling property is influenced by the free volumes, chain relaxation as well as the chemical nature of the cross linkers.
Positron Lifetimes and Crystallinity of γ-Irradiated Polypropylenes
Authors: Chen Zhe , Huang Wei , Fang Peng Fei , Yu Wen , Wang Shao Jie
Published: November 2012

The microstructure of the polypropylenes (PP) irradiated by gamma ray was studied by positron lifetime technique and differential scanning calorimetry (DSC). Lifetime measurement shows o-Ps intensity decreases with increasing γ irradiation dose. The crystallinity of irradiated samples was detected by DSC method. The correlation between o-Ps intensity and crystallinity indicates γ-ray can induce higher crystallinity in the polypropylene at low irradiation dose.
New Organic-Inorganic Hybrid Ureasil-Based Polymer Materials Studied by PALS and SEM Techniques
Authors: Kavetskyy Taras , Šauša Ondrej , Krištiak Jozef , Petkova Tamara , Petkov Plamen , Boev Viktor , Lyadov N. , Stepanov Andrey L.
Published: November 2012

The new organic-inorganic materials, based on polyether chains covalently linked to a silica framework through urea bridges, referred as ureasilicates or ureasils, and semiconducting As2S3-ureasil composites are investigated using positron annihilation lifetime spectroscopy (PALS) and scanning electron microscopy (SEM) techniques. The results obtained show that incorporation of the As2S3 clusters into ureasil affects on the ortho-positronium (o-Ps) intensity or positronium formation probability and micro-/nanoscopic structure compared to the pure polymer, the effect is more essential as the loading fraction of As2S3 increases.