bluuebunny/crossref_metadata_2025 huggingface dataset:
Characterization of Anti-Cancer Drug Materials Loaded Poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) Microspheres for Drug Delivery System in Biochemical Material System
Authors: Hui Jing , Yu Xiao Jie , Zhang Yue , Hu Feng Qing
Published: November 2012

Poly (3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBHHx) is one of the components of polyhydroxyalkanoates (PHAs) and some of its mechanical properties have been shown to improve over poly (3-hydroxybutyrate) (PHB) and poly (3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV). The investigation of PHBHHx microspheres as a drug delivery system was prepared by emulsion-solvent evaporation method for the sustained release of anti-cancer drug 5-fluorouracil (5-FU) and cyclosporin A (CsA). The mean diameter of the PHBHHx microspheres ranged from 5.24 to 22.10 μm dependent on the different processing parameters. The PHBHHx concentration, emulsifier concentration, anti-cancer drug dosage, and agitation speed, were optimized according to the encapsulation efficiency of 4% PHBHHx, 0.5% SDS, 10 mg anti-cancer drug, and 500 rpm. Under optimized conditions, the encapsulation efficiency of 5-FU and CsA microspheres were 7.19% and 96.44%, respectively. The morphologies of scanning electron microscope (SEM) suggested that PHBHHx microspheres were relatively smooth that provided better dispersion compared to PHB microspheres. The in vitro release profiles indicated 32.42% of 5-FU and 30.61% of CsA were released from PHBHHx microspheres during the initial burst phase, and the drug release from PHBHHx microsphere could be detected even after one month. The characteristics of PHBHHx microspheres demonstrated the feasibility of PHBHHx microsphere as a novel matrix for drug release system. With positive maintenance of the therapeutic concentrations of the drug, side effects can be reduced and patient compliance can be improved.
Design and Experimental Study of the Multi-Function Corn Peeling Machine with Analysis of Segmented Metal Construction Materials
Authors: Zhao Chun Hua , Zhao Tao , Hu Bao Long
Published: November 2012

Peeling roller is an important working part of multi-function corn peeling machine which can stripping the skin of eaten fresh corn, forage corn and seeding corn. The main material of peeling roller was analysed in this paper, The orthogonal experiment method was used to study the effect of peeling roller’s shape, speed and tilt angle on the corn peeling machine’s performance. The results showed that the material and type of peeling roller has the most significant impact on it. The optimal combination of three factors was A2B3C1: “person shaped” roller-type, 550r/min roller’s speed and 10°peeling angle.
Modal Analysis of the New Composite Material for Automobile Brake Pads Based on Properties of Composite Materials
Authors: Zhang Li , Ma Yan Miao
Published: November 2012

The present semi-metallic friction material reinforced by the steel fiber is still the main material of the domestic friction material industry, which is left far behind by the developed countries such as America and Japan. Therefore, based on its superior performance, a new kind of composite material used for the automobile brake pads has been developed by our team before. In order to verify its superiority, with the ANSYS software, comparative analysis of free and constraint mode was carried out on the semi-metallic brake and the new composite brake in this paper, and the modal parameters such as the natural frequency were obtained. What’s more, the modal testing was also conducted on both of them. In the end, the finite element analysis results and the experimental results were compared, which shows that compared with the traditional semi-metallic material brake, the new one with bigger damping coefficient and smaller natural frequency has better noise and vibration reduction performance.
Electrocatalytic Oxidation of Methanol on Platinum/Graphene Hybrid Modified Glassy Carbon Electrode
Authors: Xia Jian Fei , Wang Yu Feng , Wang Zong Hua , Xia Yan Zhi , Zhang Fei Fei , Yao Shu Yan
Published: November 2012

In this article, we proposed a new platinum (Pt) nanoparticles ensemble-on-graphene (G), a new electrode material, which was rapidly prepared by microwave-assisted reduction of PtCl62- on the poly (diallyldimethylammonium chloride)-modified G. The Pt/G hybrid can be directly used as electrode materials. The microstructure and morphology of the prepared film samples are characterized by TEM, and the result showed that Pt nanoparticles with averaged diameter of 2~5 nm appear as dark dots on the surface of graphene. At the same time, the electrocatalytic activities of the Pt/G hybrid modified electrodes towards methanol oxidation is evaluated through cyclic voltammetry. The as-synthesized Pt/G hybrid exhibits high catalytic activity and good stability for the oxidation of methanol, which may be attributed to its excellent electrical conductivity and the high specific surface area of the graphene catalyst support.
Microstructure of In Situ Synthesized Al3ti/6063 under Combination of Magnetic Fields
Authors: Jiao Lei , Zhao Yu Tao , Wu Yue , Zhang Sai , Wang Xiao Lu
Published: November 2012

During the process of in situ generated particles reinforced aluminum matrix composites, the introduction of the magnetic field can make the melt a forced movement, promoting changes in the conditions of melt dynamics, and thus plays the role in refining particles, changing the morphology and distribution. And particle size and distribution both are important factors affecting mechanical properties of the composite. Therefore, the introduction of the magnetic field can effectively improve the performance of composite materials. In this experiment, Al-K2TiF6 is used as reaction system to study the influence of combined rotating magnetic field on the microstructure of aluminum matrix composites, which can optimize the preparation process of aluminum matrix composites in the combined magnetic field.
Advanced Materials Application in Flat Television Steering Bracket
Authors: Zhang Xi Xi , Ren Hong Tao , Jia Yu Jing
Published: November 2012

This paper mainly talks about the problem of flat television’s placement and the creative design of this automatic steering bracket which designed on the basis of analyzing the existing brackets and aims to make televisions turning around instantly, conveniently and automatically (instead of never moved or hand operated) for people who are watching TV from whichever angle. It is the working of two small electrical motors drives the rotation of the rack at horizontal direction and vertical direction. And only with the help of its remote control can this automatic steering bracket divert the television. The bracket was made of bigger strength aluminum alloy, it is lighter weight, stainless, surface beautiful, compared with traditional processing methods, and selecting aluminum alloy can remarkably improve the production efficiency, ensure product quality and improve the qualification rate of finished products.
Nonenzymatic Electrochemical Detection of Glucose Using Well-Distributed Gold Nanoparticles on Graphene/Carbon Nanotube Nanohybrids
Authors: Lu Cai Yu , Xia Jian Fei , Wang Zong Hua , Xia Yan Zhi , Zhang Fei Fei
Published: November 2012

A nonenzymatic electrochemical sensor was fabricated for glucose detection based on gold nanoparticles graphene/carbon nanotube nanohybrids (AuNPs-GH/CNT), which were synthesized through in situ reduction procedure. Cyclic voltammetry (CV) and amperometry were used to evaluate the catalytic activity of the AuNPs-GH/CNT-Nafion modiﬁed electrode towards glucose. It was founded that AuNPs-GH/CNT-Nafion modiﬁed electrode showed remarkable enhanced electrocatalytic activity towards the oxidation of glucose under optimized conditions. The sensors exhibited linear behavior in the concentration range from 5 μM to 1 mM for the quantification of glucose with a limit of detection of 1.5 μM.
Analysis the Application of Environmental Properties of SO2 Fungicide for Extended Storage Life of Muscate Table Grapes at Room Temperature
Authors: Duan Hui Ye , Xu Wen Cai , Li Dong Li , Fu Ya Bo , Zhang Jing Yong
Published: November 2012

The germicidal bags which can release environmental properties of SO2 fungicide, have lower water vapor transmission rate and higher oxygen transmission rate, and theirs effect on preservation of table grapes was investigated during storage at room temperature. The results showed that germicidal bags were able to maintain physicochemical, and physiological quality of grapes at a higher level compared with the common LDPE bags. At 16th days, decreases in the water loss rate, berry decay rate, and contents of total soluble solids, titratable acidity of germicidal bags groups were significantly inhibited. Although the content of TSS, TA and the berry firmness didn't show the significant difference between the germicidal bags and control group, but decay rate, shatter rate, and water loss rate of the control group were increased to 5.01%, 13.58%, and 0.67%, respectively. The control group had lost edible value. The overall results expressed that grapes quality can be maintained effectively at least for 16 days using germicidal bags.
Computational Studies of Magnesium and Strontium Substitution in Hydroxyapatite
Authors: Imrie Flora E. , Corno Marta , Ugliengo Piero , Gibson Iain R.
Published: November 2012

The properties of hydroxyapatite can be improved by substitution of biologically relevant ions, such as magnesium (Mg) and strontium (Sr), into its structure. Previous work in the literature has not reached agreement as to site preferences in these substitutions, and there are suggestions that these may change with differing levels of substitution. The current work adopted a quantum mechanical approach based on density functional theory using the CRYSTAL09 code to investigate the structural changes relating to, and site preferences of, magnesium and strontium substitution (to 10 mol%) in hydroxyapatites and also to predict the corresponding vibrational spectra in the harmonic approximation. The structures underwent full geometrical optimisation within the P63 space group, indicating an energetic site preference for the Ca (2) site in the case of Mg substitution, and the Ca (1) site in the case of Sr. Shrinkage of the unit cell was observed in the case of Mg substitution, and expansion in the case of Sr substitution, in agreement with the corresponding ionic radii. Thermodynamic properties of the structures obtained from the harmonic vibrational frequency calculations confirmed that the structures were minima on the potential energy surface. Isotopic substitutions indicated that the main contribution of Sr and Mg to vibrational modes is at frequencies < 400 cm-1.
3-D Printed Bioactive Bone Replacement Scaffolds of Alkaline Substituted Ortho-Phosphates Containing Meta- and Di-Phosphates
Authors: Dombrowski F. , Caso P.W. Garcia , Laschke M.W. , Klein M. , Günster J. , Berger Georg
Published: November 2012

The paper presented here deals with the investigations of orthophosphates (Q0) containing none or differing amounts of meta-(Q2) and diphosphate phases (Q1) for the use of 3-dimensional printing process in order to create porous, bioactive, nonloadbearing bone replacement scaffolds. The main ceramic phase in all cases is Ca10[K/N(PO4)7 hereinafter called 401545(100) consisting of 99,9% Q0 and 0,1% Q1-phase. The other phosphate ceramics i) 401545(40) consists of 75% Q0-phase, 22% Q1-phase and 4% Q2-phase ii) 401545(15) consists of 65% Q0-phase, 33% Q1-phase and 2% Q2-phase iii) 401545consists of 56% Q0-phase, 40% Q1-phase and 4% Q2-phase. The in-house produced ceramics where crushed and sieved to achieve particles of irregular shape in the range of 45-90µm. These powders show a quite good flowability and were used to generate cylindrical samples with a diameter of 5,5mm and a height of 11mm via 3-dimensional printing using a R1 printer from ProMetal company (USA). After drying the samples at T=125°C for 48 hours they were sintered at temperatures according to the thermal analysis results in the range of 900°C up to 1300°C. Afterwards the porosity, the linear shrinkage and the compressive strength were determined.
Fabrication of Calcite Foam by Inverse Ceramic Foam Method
Authors: Thanh Tram Nguyen Xuan , Maruta Michito , Tsuru Kanji , Valanezhad Alireza , Matsuya Shigeki , Kunio Ishikawa
Published: November 2012

We have previously reported that calcite foam that had interconnected porous structure could be prepared by ceramic foam method and it transformed to carbonate apatite (CO3Ap). In the ceramic foam method, polyurethane sponge was used as a template. The polyurethane sponge was immersed in the ceramics slurry, and the strut of the polyurethane foam was covered by ceramic powder. After that it was dried and sintered at high temperature. Calcite foams produced by this approach were comprised of a three-dimensional (3D) interconnected porous structure that facilitated cell penetration. However, all foams have a common limitation: the inherent lack of mechanical strength associated with high porosity. Therefore, in this study, an inverse ceramic foam method was studied; multi polyurethane coating method using polyurethane foam as a template. In this study, the compressive strength was improved by an inverse replication allowed for decreasing porosity while at the same time maintaining the interconnectivity. The burnable synthetic resin coating layer was introduced onto struts of polyurethane foam to make the triangular struts become more round and thick, consequently producing large round capillary within the foam structure fulfilling the requirement for osteoblast colonization. In particular, polyurethane foam was dipped orderly into two monomers, followed by centrifugation to remove excess liquids inside foam. After resin curing, a layer of synthetic resin was coated strut of foam. Calcium hydroxide Ca (OH)2 slurry was then infiltrated into resin coated-polyurethane foam. By firing at 600°C in O2-CO2 stream, polyurethane template was burnt off and Ca (OH)2 was converted into calcite. Negative replicated calcite foam was fabricated and characterized micro-structurally with interconnectivity and improved mechanical strength. The results obtained in this study suggested that this method dramatically improved the mechanical strength of the calcite foam without sacrificing the interconnected structure, and this means that the calcite foam obtained in this method could be precursors for the 3D interconnected porous CO3Ap foam.
Studies on the Anti-Tumor Action of Chelate-Setting Apatite Cements
Authors: Inayama Tetsuya , Konishi Hidenori , Aizawa Mamoru , Kanzawa Nobuyuki
Published: November 2012

Chelate-setting apatite cement is a novel biomaterial developed as a bone substitute. We previously reported a chelate-setting apatite cement, IP6-HAp, which exhibits anti-tumor activity via apoptotic cell death. However, our preliminary data showed that excess IP6 arrests osteoblast growth. We found that a high, transient amount of IP6 was released from the cement. We therefore hypothesized that a high performance cement specific for tumor cells can be developed by controlling the release of IP6 from the cement. To validate this, we used a murine calvarial osteoblast cell line (MC3T3-E1) and a human osteosarcoma cell line (HOS). Culturing HOS or MC3T3-E1 in medium containing various concentrations of IP6 more effectively arrested the growth of HOS than that of MC3T3-E1. Although the proliferation of osteoblasts was suppressed at early growth stages in response to the release of IP6 from the cements, there was no difference in the number of cells after a prolonged culture period. In contrast, osteosarcoma cell growth remained suppressed even after a prolonged culture period. To better understand why these two cell types respond differently to IP6, we investigated cell viability by measuring the ratio of living and dead cells. Our findings suggest that this novel bone graft cement will find unique uses due the different sensitivity of tumor cells and osteoblasts towards IP6.
In Vitro Evaluation of Chelate-Setting Cements Fabricated from Silicon-Containing Apatite Powder Using Osteoblastic Cells
Authors: Nakashima Yusuke , Honda Michiyo , Konishi Toshiisa , Mizumoto Minori , Aizawa Mamoru
Published: November 2012

In our previous study, silicon-containing hydroxyapatite (Si-HAp) powder was prepared via an aqueous precipitation reaction. The Si-HAp powders were synthesized with desired Si contents (0, 0.4, 0.8, 1.6, and 2.4 mass%) as a nominal composition. Another previous study in our group demonstrated surface-modification of HAp powder with inositol phosphate (IP6) enhanced the compressive strength of apatite cement. Thus, to fabricate the cements with higher bioactivity, the above Si-HAp powders were surface-modified with IP6 (IP6-Si-HAp). The IP6-Si-HAp cements with various Si contents were fabricated by mixing with pure water at the powder/liquid ratio of 1/0.4 [w/v]. In order to clarify biocompatibility of the IP6-Si-HAP cements in the present work, MC3T3-E1 cells as a model of osteoblast were seeded on the cement specimens. As for the numbers of cells cultured on the IP6-Si-HAp cements, the substitution of lower levels of Si into HAp lattice did not greatly influence the cell proliferation. However, the substitution of Si amount over 0.8 mass% enhanced the cell proliferation. Especially, the IP6-Si-HAp cement with the Si content of 2.4 mass% showed excellent cell proliferation among examined specimens. Therefore, to fabricate the cements with higher bioactivity, it is necessary to control the amount of Si in the IP6-Si-HAp cements. The usage of these IP6-Si-HAp cements may make it possible to fabricate the cements with higher bioactivity, compare to conventional pure HAp cements.
Evaluation of the Anti-Bacterial Activity of a Novel Chelate-Setting Apatite Cement Containing Lactoferrin
Authors: Ohsugi Hitomi , Habuto Yuri , Honda Michiyo , Aizawa Mamoru , Kanzawa Nobuyuki
Published: November 2012

We have developed a chelate-setting apatite cement. Synthesized hydroxyapatite (HAp) powders surface-modified with inositol hexaphosphate (IP6-HAp powder) were set by chelate-bonding with inositol hexaphosphate (IP6). Our aim is to fabricate IP6-HAp cement with anti-bacterial activity by adding lactoferrin (LF). It is known that LF has both anti-bacterial and osteoinductive activity. Gram-positive Staphylococcus aureus and Gram-negative Escherichia coli were used to examine the effect of LF on biofilm formation and localization of living and dead cells. In addition, the cell viability of MC3T3-E1 osteoblastic cells was determined. Our results show that the anti-bacterial activity of LF is not due to a bactericidal effect but to the inhibition of bacterial adhesion to surfaces. Furthermore, LF cement did not affect cell proliferation. Thus, LF cement is a candidate for bifunctional biomaterials having both anti-bacterial and osteo-conductive activity.
Improvement in Handling Property of αTCP Cement
Authors: Maruta Michito , Matsuya Shigeki , Tsuru Kanji , Kunio Ishikawa
Published: November 2012

This study aims to improve the handling property of alpha-tricalcium (αTCP) cement. In order to improve the handling property, the effect of γ-poly-glutamic acid (γPGA) as a chelating agent was studied. γPGA is water soluble, biodegradable, nontoxic, and edible material. γPGA contains carboxyl group, so the chelating effect between Ca2+ ions released from calcium phosphate cement and carboxyl group of γPGA is prospected when it mixed with αTCP based cement. The results obtained in this study clearly demonstrated that the addition of γPGA into the αTCP cement was highly effective in controlling the handling property of αTCP cement.
Formation of Hydroxyapatite on Nickel-Free High-Nitrogen Stainless Steel by Chemical Solution Deposition Method in Neutral/Alkaline Solution
Authors: Sasaki Makoto , Inoue Motoki , Katada Yasuyuki , Hiromoto Sachiko , Taguchi Tetsushi
Published: November 2012

Calcium phosphate (CaP) was formed on glutamic acid-modified nickel-free high-nitrogen stainless steel (HNS) by a chemical solution deposition method in neutral/alkaline solution. Modification of glutamic acid on the surface of HNS was performed using trisuccinimidyl citrate (TSC) as a linker. The glutamic acid-derived carboxyl groups introduced on HNS initiated rapid nucleation of CaP during each treatment at pH 7.3 or 8.9. X-ray diffraction analysis and Fourier transform infrared spectra showed each CaP deposited on glutamic acid-immobilized HNS after 24 hrs was identified as low-crystallinity calcium-deficient carbonate-containing hydroxyapatite (HAp). A significant difference in the microstructure between the two pH values was observed; HAp deposited at pH 7.3 was composed of plate-like crystals, whereas that at pH 8.9 was chestnut-like crystals. Therefore, the pH value of the solution played an effective role in controlling the microstructure of HAp deposited on glutamic acid-immobilized HNS.
Protectivity and Adhesive Strength of Zinclipscombite Coating on 316L Stainless Steel
Authors: Valanezhad Alireza , Tsuru Kanji , Maruta Michito , Matsuya Shigeki , Kunio Ishikawa
Published: November 2012

Zinclipscombite (ZnFe3+2(PO4)2(OH)2) coating layer was prepared on 316L SS. The 316L SS plates were treated using hydrothermal treatment at 200°C for 2, 6 and 24 h. The ZnFe3+2(PO4)2(OH)2 layer strongly attached to the 316L SS surface. The adhesive strength of the coating layer was measured higher than 65.7 ± 3 MPa. The surface observation and element analysis indicated that the 316L SS plates were covered with ZnFe3+2(PO4)2(OH)2 coating layer after hydrothermal treatment. Linear voltammograms for treated sample at 200°C for 24 h showed higher corrosion resistance. The ICP results proved protective property for the zinclipscombite coating agains PBS solution.
Bone Grafting Putty – Animal Experiments and Clinical Applications
Authors: Gerber Thomas , Ganz Cornelia , Xu W. , Maier F. , Frerich B. , Lenz S.
Published: November 2012

The aim of the described study was to generate and evaluate a putty-like bone graft substitute ready to use for dental and orthopedic surgery. According to the asking of clinicians the new material should avoid the necessity of mixing blood and bone graft during the surgical process. Therefor the granulous material NanoBone® has been combined with a hydrogel based on Polyvinylpyrrolidone (PVP) and tested in standardized rat tibia defect over a period of 12 weeks and evaluated histologically. The results showed no limitations of the granulate characteristics in matrix change and hence a high level of vascularization and bone formation. An example for dental application shows the outcome in the case of socket preservation.
Influence of Niobium Oxide on the Mechanical Properties of Hydroxyapatite
Authors: Demirkol N. , Oktar F.N. , Kayali E.S.
Published: November 2012

The goal of this study is to produce and to investigate the mechanical and microstructural properties of composite materials made of hydroxyapatite, obtained from both natural sheep bone and commercial synthetic hydroxyapatite with niobium oxide addition ( 5 and 10 wt%). The samples were subjected to sintering at different temperatures between 1000°C and 1300°C. Microstructures and mechanical properties of sheep hydroxyapatite (SHA) and commercial synthetic hydroxyapatite (CSHA)-niobium oxide composites were investigated. The production of hydroxyapatite (HA) from natural sources is preferred due to economical reason. The aim of development of SHA and CSHA based niobium oxide composites is to improve mechanical properties of HA. The physical and mechanical properties were determined by measuring density, compression strength and Vickers microhardness (HV). Structural characterization was carried out with X-ray diffraction (XRD) and scanning electron microscopy (SEM) studies. In all composites, density values and mechanical properties increased with increasing sintering temperature. The increase of niobium oxide content in all composites showed better mechanical properties. Both of SHA and CSHA composites with at 1300°C sintering temperature showed nearly the same compression strength value.
Lectinhistochemistry Evaluation of Rabbits Tibia Implanted with Macroporous Biphasic Ceramic Implants
Authors: Violin Kalan Bastos , Ribeiro Christiane , Goia Tamiye Simone , Bressiani José Carlos , Bressiani Ana Helena de Almeida
Published: November 2012

Many techniques are used to assess biomaterials implants, always intending to measure osseointegration success and tissue response facing the implanted material. Calcium phosphates are widely used as biomaterial and a major component of bone. Many processing methods have been used to achieve porous materials to allow bone ingrowth with an osteoconductive scaffold for bone. To obtain the macroporous BCP implant it was processed by direct consolidation using the protein-action technique, a globular protein based consolidation with ovalbumin. The samples were sintered at 1250°C for 30 minutes, after sintering samples were cut in 4mm diameter cylinders, with 73% volume of porosity and mean pore size ranging about 100 µm. In the present work the macroporous BCP of HAp:β-TCP is assessed after bone implantation in rabbits tibia by lectinhistochemistry (LHC) technique. Lectins are proteins from non-imune origin which binds with strong specificity carbohydrates, LHC is a technique which mark histologically carbohydrates present in glycoproteins of cells. The macroporous BCP cylindrical samples were implanted in male rabbits tibia to the evaluation of biocompatibility and osseointegration in a period of 2 weeks to 4 weeks. After euthanasia of rabbits, tibia samples from the surgery site were taken and fixed with formalin, decalcified, dehydrated and embedded with paraffin to perform histological slides for both morphological and molecular evaluation. The morphological evaluation were performed on histological slides stained with Haematoxilin and Eosin (HE), while for molecular evaluation LHC was performed on histological slides using the lectins PNA, UEA-1, WGA, sWGA and RCA-1 (Vector Labs). All samples osseointegrated well with the bone and the neoformed bone surrounding the implant took the shape of its surface. The implants also allowed bone ingrowth inside the pores towards the center of implant, characterized by islets of round bone present in the HE stained slides.
Surface Electric Fields of Apatite Electret Promote Osteoblastic Responses
Authors: Nakamura Miho , Nagai Akiko , Yamashita Kimihiro
Published: November 2012

The osteoblast behaviors on the biomaterial substrates are recognized to play a fundamental role in osteoconduction process. The purpose of this study was to evaluate the in vitro behaviors of osteoblasts cultured on electrically polarized hydroxyapatite (HA), having the enhanced osteobonding abilities. Osteoblasts derived from mouse bone marrow were seeded onto the polarized HA and investigated the proliferation and differentiation. The polarization had effects on the proliferation of osteoblast precursor cells based on the MTT assay. The acceleration was emerged as the early achievement to the confluence on the N-HA and P-HA. The quantitative analysis of the results of ALP and AR-S staining, the charges induced on the HA surface accelerated the differentiation from the osteoblast precursor cells to mature osteoblasts.
MC3T3-E1 Cell Response to Hydroxyapatite and Alpha-Type Alumina Adsorbed with Bovine Serum Albumin
Authors: Hayashi Jumpei , Masakazu Kawashita , Miyazaki Toshiki , Kudo Tada Aki , Kanetaka Hiroyasu , Hashimoto Masami
Published: November 2012

MC3T3-E1 cell responses, such as cell adhesion and proliferation, to original and bovine serum albumin (BSA) coated disc (original-disc, BSA-disc) of hydroxyapatite (HA) or alpha-type alumina (α-Al2O3) was studied. There was no significant difference in the cell proliferation between BSA-discs and original-discs even after incubated for 14 days, but the cell number at day 14 tended to be higher (p = 0.054) on the BSA-discs of HA than on the original-discs of HA. Incidentally, the amount of adsorbed protein was higher on BSA-discs than on original-discs only until incubated in culture medium for 3 h. BSA adsorption might influence the MC3T3-E1 cell adhesion to HA, as a result the specific adsorption of albumin on HA is likely to affect the expression of the osteoconductivity of materials.
Murine Macrophage RAW264.7 Cells Response for the Carbon Nanotubes Immobilized on Substrate
Authors: Akasaka Tsukasa , Abe Shigeaki , Watari Fumio
Published: November 2012

The reports on cytotoxic studies of carbon nanotubes (CNTs) increased exponentially. In the present study, we investigate murine macrophage RAW264.7 cell response for the CNTs immobilized on a polystyrene substrate. We prepared CNT-coated dishes, and estimate the interaction of RAW264.7 cells with CNTs by cell adhesion, proliferation assay, and measurement of TNF-α production. As a result, the highest cell adhesion and proliferation was observed on a commercially cell culture polystyrene dish, while CNT-coated dish indicate slightly lower activity of them. Moreover, amount of production of TNF-α on the CNT-coated dishes was considerable lower than that in the case of lipopolysaccharide (LPS) addition as a control. These results indicated that CNT-coated dishes could not show strong cytotoxicity for RAW264.7 cells in vitro.
Processing and Characterization of a Composite of Hyaluronic Acid (HA) and Microspheres Biphasic Calcium Phosphate (BCP) for Dermal Repair
Authors: Silva Edirlaine Soares , de Freitas Deny Gomes , da Silva Sidney Nicodemos
Published: November 2012

Dermal fillers are injectable implants made of biological materials (collagen, autologous fat and hyaluronic acid animal) or synthetic (PMMA microparticles of hydroxyapatite and non-animal hyaluronic acid), biodegradable or not, that include features such as ideal biocompatibility, durability, non-profile migration and ability to promote a smooth, natural-looking correction. Its main indication is intended to treat contour defects caused by aging, photo damage, disease, trauma or scarification. The fact of biodegradable fillers are absorbed within a year after application resulted in the emergence of products permanent and semi-permanent to offer patients long-lasting effects. Currently, one of the most effective strategies has been the development of scaffolds formed by combining two or more biomaterials seeking the restoration of tissue function. The bioceramic associated with water-soluble polymers have been developed as substitutes for the repair of soft tissues with optimal biological response. The objective of this study was to process and characterize a composite hydrogel in the form of hyaluronic acid (HA) microspheres and biphasic calcium phosphate (BCP) in order injectable applications for repair of soft tissue. The powders of HA and BCP were characterized by Infrared Spectroscopy Fourier Transform (FTIR) and X-ray diffraction (XRD) and Scanning Electron Microscopy (SEM). The characterization of the hydrogel injectability pure and the composite with different ratios of HA and BCP was performed. The components were characterized compatible for use as dermal fillers. The composite of hyaluronic acid (HA) and biphasic calcium phosphate (BCP) had adequate characterization and injetabilidade proving to be a potential candidate for restoration of soft tissue.
Fabrication of Composites from Apatite and Chemically Synthesized Collagen
Authors: Miyazaki Toshiki , Kuramoto Akimasa
Published: November 2012

Chemically synthesized collagen with triple helix structure similar to natural collagen has been developed as a safe biomaterial. If the chemically synthesized collagen is deposited with apatite, they are expected for novel bone substitutes having bioactivity and bioresorbability. Although apatite formation on the chemically synthesized collagen has been examined, highly supersaturated condition such as 1.5SBF with ion concentration 1.5 times those of simulated body fluid (SBF) is needed to achieve apatite formation. In the present study, we intended acceleration on the apatite formation on the chemically synthesized collagen by immobilization with polyglutamic acid (PGA). PGA is known as biodegradable and biocompatible polypeptide having excellent apatite-forming ability. We examined effects of the immobilization procedure on mineralization behavior in SBF. At first, PGA was immobilized on porous sponges of chemically synthesized collagen in aqueous solutions containing PGA and CaCl2. As a result, not only apatite but also calcite-type CaCO3 was deposited on the specimens in SBF. The calcite formation was occurred during the treatment with PGA solution. pH of the solution was adjusted to 7 by NaOH solution in order to avoid dissolution of the collagen. During this procedure, Ca (OH)2 would be precipitated by locally increase in pH of the solution and converted into the calcite. When the PGA solution treatment was shortened so as to prevent the calcite formation, single phase of the apatite was formed in SBF. The present results indicate that crystalline phase deposited on the chemically synthesized collagen can be controlled by fabrication procedure, and provide fundamental design of composites containing apatite and chemically synthesized collagen useful for bone regeneration.
Reaction of Dental Zirconia with Phosphate-Bonded Investments for Heat Pressing Technique
Authors: Yoshihara Kentaro , Ban Seiji , Kawai Tatsusi , Tanaka Yoshinobu
Published: November 2012

The aim of the study was to investigate the reaction of phosphate bonded investment to zirconia during for the heat-pressing technique. Two kinds of dental zirconia were used in this study (inCoris ZI and P-NANOZR). Zirconia was invested into the three kinds of phosphate-bonded investment (Ceravety, PC-15 and Norivest). The investments were fired at several different temperatures. The X-ray diffraction peaks due to monoclinic ZrO2 were not detected on the waxed-up side of zirconia discs. It demonstrates that no low temperature degradation occurred during the heating of the investment. X-ray diffractometry revealed that the peak assigned to ZrP2O7 was detected on the contact side of zirconia discs fired with phosphate-bonded investment at 850 and 950°C. It also revealed that diffraction peak assigned to YPO4 and the monoclinic ZrO2 were detected in the same side of zirconia discs contacted with phosphate-bonded investment fired at 1100 °C. It can be concluded that the reduction of Y caused the transformation from tetragonal to monoclinic phase and the reduction of strength.
Biocompatibility and Biodistribution of Several Nano-Sized Ceramics Particles
Authors: Abe Shigeaki , Hamba Yusaku , Iwadera Nobuki , Akasaka Tsukasa , Yamagata Shuichi , Yawaka Yasutaka , Iida Junichiro , Uo Motohiro , Yonezawa Tetsu , Watari Fumio
Published: November 2012

We succeeded in determination the biodistribution of several nano-sized particles administered to mice through the tail vein. After administration, these particles were observed in the lung, liver and spleen. The distribution behaviors depend upon not only chemical species but also the particles size. To estimate their cytocompatibility, these particles were exposed to osteoblastic cell at several concentrations. When the concentration reached at 10 ppm, their viability remained at 80% or more even nano-sized particle contained rare earth element. Only CuO particles indicated the viability decrease. The effect depended on the particle size. These results suggested that the chemical species played a dominant key in the biodistribution and biocompatibility of nanoparticles compared with the size-effect.
Inhibitory Effects of Doped Aluminum and Silicon on HAp-Forming Ability of Titania in Simulated Body Fluid
Authors: Shin Euisup S. , Kim Ill Yong , Cho Sung Baek , Ohtsuki Chikara
Published: November 2012

Chemical modification of titanium substrate provides ability of hydroxyapatite (HAp) formation that is important property for bone-bonding capability after implantation in bony defects. Potential of the HAp-formation is occasionally reduced. In the present study, we investigated potential of the HAp-formation on titanium oxide (titania) with doped silicon or aluminum in simulated body fluid (SBF). Sol-gel processing was applied to prepare titania with doped silicon (TSx) or aluminum (TAx), in its nominal composition ranging from 0 to 10 mol%. Specific surface area of the prepared samples was gradually increased with increasing the amounts of silicon or aluminum. Zeta potential of TAx was definite changed from negative charge to positive charge with increasing aluminum amounts, but TSx slightly changed to be positive with increasing silicon amounts. The pure titania sample free from doping of silicon or aluminum showed formation of calcium phosphate precipitates, that is HAp-formation, after soaking in SBF for 14 d. In contrast, all the titania samples with doped silicon or aluminum hardly showed evidence of precipitates of calcium phosphates, although absorption of calcium and phosphate ions were detected. Especially, TAx showed remarkable adsorption of phosphate ions. Aluminum-doping in titania enhances the adsorption of phosphate ion on the surface, but reduce nucleation rate of calcium phosphates in body environment.
Investigation of Multilayered Protein Adsorption on Carbonate Apatite with a QCM Technique
Authors: Yoshioka Tomohiko , Yonekura Hiroshi , Ikoma Toshiyuki , Tagaya Motohiro , Tanaka M.
Published: November 2012

This study is concerned with multilayered protein adsorption on carbonate apatite (CAp) that is measured with a quartz crystal microbalance (QCM) technique. A carbonate apatite-deposited QCM sensor was prepared by electrophoretic deposition (EPD). On the CAp-deposited QCM sensor, fibrinogen adsorption followed by thrombin adsorption was investigated. The adsorption of fibrinogen on CAp led to a clear decrease in the resonance frequency of the sensor, which means that fibrinogen adsorbed on the CAp-deposited QCM sensor. The adsorbed amount of fibrinogen was larger on CAp than on a pristine sensor (Au). Although successive thrombin adsorption occurred on fibrinogen adlayers on both CAp and Au, the adsorbed amount and its conformation were different depending on the surface.
Fabrication of Spherical Carbonate Apatite Using Calcium Sulfate as a Precursor by W/O Emulsion Method
Authors: Nomura Shunsuke , Tsuru Kanji , Matsuya Shigeki , Takahashi Ichiro , Kunio Ishikawa
Published: November 2012

We fabricated spherical carbonate apatite from spherical calcium sulfate which was prepared by w/o emulsion method. Calcium sulfate hemihydrate slurry was dropped in oil under continuous stirring and was kept at room temperature for 60 min to obtain set spherical calcium sulfate dihydrate (CaSO42H2O) with approximately 1 mm in diameter. The spherical CaSO42H2O was hydrothermally-treated at 120°C for 24 hours in the presence of 0.4 mol.L-1 disodium hydrogen phosphate and sodium hydrogen carbonate aqueous solution. X-ray diffraction patterns assigned to apatite single phase could be detected from the obtained spheres. Carbonate content in apatitic structure was found to be approximately 6.5wt%.
Relationships between Positron Lifetime and Dynamics of Polymers
Authors: Yu Yang , Dlubek Günter , Bartoš Josef , Švajdlenková Helena , Krause-Rehberg Reinhard
Published: November 2012

In this work positron annihilation lifetime spectroscopy (PALS) is employed to study the ortho-Positronium lifetime parameters τ3>, σ3 and I3 in two structurally simple amorphous polymers 1,2-poly(butadiene) and cis-1,4-poly(isoprene). The ortho-Positronium mean lifetime parameter τ3> is compared with dynamics data from broadband dielectric spectroscopy (BDS) and electron spin resonance (ESR) experiments. Coincidences of characteristic temperatures from PALS with BDS and ESR experiments show close relationships between positron lifetime and dynamics of polymers.
On the Relationship of the Relative Intensity I3 and a Cavity Number as Obtained from Computer Simulations
Authors: Račko Dušan
Published: November 2012

In this contribution a generalized picture of the cavity number behavior is obtained by means of molecular dynamics simulations and consequent free volume analysis. The cavity number obtained for free volume cavities defined by different probe radii shows a complex behavior with the temperature. The number of cavities determined by small probes drops with the temperature. The number of cavities determined by large probes increases. This complex behavior of the cavity number can be discussed with the distinct behavior of the relative intensity, as observed in the experiment, and a support for the most basic of assumptions, that the cavity number relates to the relative intensity, is given.
Argon Plasma Decomposition of Porogen in Mesoporous Silica Films Studied by Positron Annihilation
Authors: He Chun Qing , Ito Kenji , Oka Toshitaka , Kobayashi Yoshinori , Ohdaira Toshiyuki , Suzuki Ryoichi
Published: November 2012

Mesoporous silica films on Si wafers were prepared via a sol-gel process using a triblock copolymer as the structural template. Spin-coated films were dried and subsequently subjected to Ar plasma treatments for decomposing the polymeric porogen. Mesopore formation in the silica film upon Ar plasma treatments was investigated by positron annihilation lifetime spectroscopy. In comparison with calcined silica film, much larger pores, more heterogeneous in size were found in silica film prepared with Ar plasma decomposition of the porogen.
In Situ Monitoring of Adsorption and Desorption of n-Heptane on Porous Silica by Positron Annihilation Lifetime Spectroscopy
Authors: Zaleski Radosław , Dolecki Waldemar , Goworek Jacek
Published: November 2012

Positron annihilation lifetime spectroscopy study of n-heptane adsorption and desorption on silica gel Si-60 gives insight into a free volume evolution during those processes. Analysis of the lifetime distribution allows to ascribe particular ortho-positronium components to silica walls, mesopores and n-heptane. Hysteresis loop of the intensities of the mesopore and n-heptane related components similar to classic adsorption/desorption isotherms is observed. Transition from an adsorbate multilayer structure to liquid when pores become completely filled, manifests itself as an intensity change. Kinetics of desorption and adsorption studies allows to determine the time of reaching the equilibrium by the Si 60–n-heptane system at various pressures.
Hydrogen Interaction with Defects in ZnO
Authors: Lukáč František , Čížek Jakub , Vlček Marián , Procházka Ivan , Vlach Martin , Anwand Wolfgang , Brauer Gerhard , Traeger Franziska , Rogalla Detlef , Becker Hans Werner , Wagner Stefan , Uchida Helmut , Bähtz Carsten
Published: November 2012

In the present work hydrothermally grown ZnO single crystals were electrochemically charged with hydrogen. The influence of hydrogen on ZnO microstructure was investigated by positron annihilation spectroscopy (PAS) combined with X-ray diffraction (XRD) using synchrotron radiation. Hydrogen concentration in the samples was determined by nuclear reaction analysis (NRA). It was found that a high concentration of hydrogen can be introduced into ZnO by electrochemical loading. At low concentrations, absorbed hydrogen causes elastic volume expansion of ZnO crystal. At higher concentration, hydrogen-induced stresses exceed the yield stress in ZnO and plastic deformation of the crystal takes place leading to formation of a defected subsurface layer in the crystals.
Hydrogen-Induced Defects of Subsurface Layer in ZnO Single Crystal Probed by a Slow Positron Beam
Authors: Xue X.D. , Wang T. , Jiang J. , Li P.H. , Liu Y.F. , Wu Yi Chu
Published: November 2012

Hydrogen-induced defects of ZnO single crystals electrochemically charged with hydrogen have been investigated by positron beam-based Doppler broadening spectroscopy, X-ray diffraction (XRD) and optical microscopy (OM). XRD and OM results indicated that a deformation layer was formed due to hydrogen-induced structural change at the subsurface of ZnO single crystal. Slow positron beam measurements showed that this deformation layer contained many defects, such as dislocations and Zn vacancies, which led to increase of S parameter.
Positron Annihilation Study of Neutron-Irradiated Nuclear Reactor Pressure Vessel Steels and their Model Alloy: Effect of Purity on the Post-Irradiation Annealing Behavior
Authors: Kuramoto Akira , Nagai Yasuyoshi , Toyama T. , Takeuchi T. , Hasegawa M.
Published: November 2012

Post-irradiation annealing (PIA) behavior of irradiation-induced microstructural changes and hardening of two kind of A533B (first generation (1stGENS: 0.16 wt.% Cu) and second generation (2ndGENS: 0.04 wt.% Cu)) steels after neutron-irradiation of 3.9 × 1019 n cm–2 at 290 °C has been studied by positron annihilation spectroscopy, atom probe tomography and Vickers microhardness measurements. In the 1stGENS, clear two recovery stages are observed: (i) as-irradiated state to 450 °C and (ii) 450 to 600 °C. The first stage is due to annealing out of the most of irradiation-induced vacancy-related defects (VRDs), and the second stage corresponds to dissolving irradiation-induced Cu-rich solute nano-clusters (CRSCs). The experimental hardening is almost twice of the hardening due to the CRSCs estimated by Russell-Brown model below 350 °C, but almost the same as the estimation from 400 to 550 °C. In the 2ndGENS, the VRDs and non-Cu-rich solute nano-clusters (NCRSCs) recover at 450 °C. No CRSC has been formed even in all the annealing process. The experimental hardening is almost twice of the hardening estimated due to the NCRSCs by Russell-Brown model below 400 °C.
Vacancy Type Defects in Oxide Dispersion Strengthened Steels
Authors: Slugeň Vladimir , Veterníková Jana , Degmová Jarmila , Kilpeläinen S. , Tuomisto F. , Kršjak V.
Published: November 2012

This study was focused on commercial oxide-dispersion strengthened (ODS) steels - MA 956 (20%Cr), PM 2000 (19%Cr), ODM 751 (16%Cr) and MA 957 (14%Cr) developed for fuel cladding of GEN IV reactors. The ODS steels are described in order to comparison of their microstructure features. Vacancy defects were observed by Doppler Broadening Spectroscopy (DBS) and Positron Annihilation Lifetime Spectroscopy (PALS). Residual stress proportional to all kinds of defects was investigated by Magnetic Barkhausen Noise (MBN) measurement. The highest presence of open volume defects was found in MA 956 and the lowest defect concentration in MA 957, although this steel contains the largest defects (six-vacancies together with dislocations). Other investigated steels demonstrated probably three- or four-vacancy clusters. Further, results from positron technique indicated proportionality of chromium content to defect concentration. Magnetic Barkhausen noise results also showed that Hpeak value (describing grain size) increased with growth of chromium content. However residual stress was independent on chromium level.
Recent Developments and Future Plans for the Accelerator Based Slow Positron Facilities at AIST
Authors: O'Rourke Brian E. , Oshima Nagayasu , Kinomura Atsushi , Ohdaira Toshiyuki , Suzuki Ryoichi
Published: November 2012

We describe the recent installation of a new slow positron beamline at AIST and our plans to develop a dedicated superconducting accelerator for positron production. The new positron beamline is already installed and should be operational by the end of this fiscal year (March 2012). Initially positrons will be generated using a 70 MeV electron beam from the existing accelerator directed onto a newly installed converter and moderator assembly. The beamline has two experimental ports both dedicated to positron lifetime spectroscopy, one port with a focused beam (diameter ~ 30 microm) and the other unfocussed (~ 10 mm). A superconducting accelerator for positron production is currently under development. When completed, it will deliver a high frequency (~ MHz), high current (~ mA), short pulse length (< 100 ps) beam to the positron production target. We investigate the possibility of transporting the positron pulses thus produced directly onto samples for lifetime measurement. Such a scheme would remove the necessity for pulse stretching and chopping which is required with the existing LINAC and should allow for greatly increased slow positron transport efficiency.