bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of intramammary infusion of cis–urocanic acid on mastitis-associated inflammation and tissue injury in dairy cows
Authors: Bannerman Douglas D. , Rinaldi Manuela , Vinyard Bryan T. , Laihia Jarmo , Leino Lasse
Published: March 2009

Objective—To evaluate the effects of cis–urocanic acid (cis-UCA) on mammary gland (MG) inflammation and injury associated with Escherichia coli–induced mastitis in dairy cows.

Animals—12 lactating dairy cows (36 MGs).

Procedures—At 7-week intervals, a different MG in each cow was experimentally inoculated with E coli. At 6-hour intervals from 6 to 36 hours after inoculation, the inoculated MG in each cow was infused with 40 mL of saline (0.9% NaCl) solution, 12.5mM cis-UCA, or 25mM cis-UCA (4 cows/group); ultimately, each cow received each treatment. Immediately prior to and at various time points after inoculation and treatment, milk samples were collected. Bacterial CFUs, somatic cell counts (SCCs), N-acetyl-beta-D-glucosaminidase (NAGase) and lactate dehydrogenase (LDH) activities, and concentrations of bovine serum albumin, tumor necrosis factor-α, and cis-UCA were quantified in each milk sample.

Results—Compared with findings in saline solution–treated MGs, NAGase and LDH activities in milk samples from cis-UCA–treated MGs were lower. Cis-UCA had no effect on milk SCCs and milk concentrations of bovine serum albumin and tumor necrosis factor-α. Furthermore, cis-UCA had no adverse effect on bacterial clearance; CFUs of E coli in MGs treated with saline solution or cis-UCA were equivalent.

Conclusions and Clinical Relevance—In cows, milk NAGase and LDH activities were both lower in E coli–infected MGs infused with cis-UCA than in those infused with saline solution, which suggests that cis-UCA reduced mastitis-associated tissue damage. Furthermore, these data indicated that therapeutic concentrations of cis-UCA in milk can be achieved via intramammary infusion.
Identification of Escherichia coli and Salmonella enterica organisms with reduced susceptibility to ceftriaxone from fecal samples of cows in dairy herds
Authors: Heider Luke C. , Funk Julie A. , Hoet Armando E. , Meiring Richard W. , Gebreyes Wondwossen A. , Wittum Thomas E.
Published: March 2009

Objective—To estimate the relationship between therapeutic use of ceftiofur and recovery of Escherichia coli and Salmonella spp with reduced susceptibility to ceftriaxone from feces of dairy cattle.

Animals—3,840 mature dairy cows on 50 dairy herds in Ohio.

Procedures—Fecal samples were obtained from up to 100 mature dairy cows on each farm. Samples were screened for E coli and Salmonella spp with reduced susceptibility to ceftriaxone by use of selective media.

Results—E coli with reduced susceptibility to ceftriaxone was recovered from 92% (46/50) of the herds and 60.9% (2,338/3,840) of cows. Salmonella spp were recovered from 44% (22/50) of the herds and 9.9% (382/3,840) of cows. No association was found between ceftiofur use and recovery of E coli with reduced susceptibility to ceftriaxone at the herd level. However, recovery of E coli with reduced susceptibility to ceftriaxone was more likely from cows in herds in which Salmonella spp were also recovered on the day of collection (odds ratio, 24.96; 95% confidence interval, 3.17 to 196.68) than from herds in which Salmonella spp were not recovered. Odds of recovery of E coli with reduced susceptibility to ceftriaxone from an individual cow increased 62% (odds ratio, 1.62; 95% confidence interval, 1.16 to 2.25) for every 454-kg increase in herd milk production.

Conclusions and Clinical Relevance—No evidence was found that the use of ceftiofur on dairy farms increases the prevalence or dissemination of Salmonella spp or E coli with reduced susceptibility to ceftriaxone.
Cardiovascular effects of fentanyl and propofol on hemodynamic function in rabbits
Authors: Baumgartner Christine M. , Koenighaus Hilke , Ebner Johanna K. , Henke Julia , Schuster Tibor , Erhardt Wolf D.
Published: March 2009

Objective—To evaluate short-term cardiovascular effects after IV administration of boluses of fentanyl in rabbits.

Animals—6 healthy New Zealand White rabbits.

Procedures—Each rabbit was anesthetized with propofol (4.0 to 8.0 mg/kg, IV); anesthesia was maintained by administration of propofol (1.2 to 1.3 mg/kg/min, IV). Subsequently, 3 injections of fentanyl (0.0053 mg/kg) were administered. Before and for 10 minutes after injections, the following variables were measured: vessel diameter, peak systolic blood flow velocity, minimum diastolic blood flow velocity, end-diastolic blood flow velocity, time-average blood flow velocity, mean volumetric flow (VFmean), resistance index (RI), and pulsatility index for the left common carotid artery after the first injection and abdominal aorta after the third injection; mean arterial pressure (MAP); heart rate (HR); arterial oxygen saturation; end-tidal partial pressure of carbon dioxide; and body temperature. Echocardiography was performed after the second injection.

Results—Fentanyl injections caused a transient and significant decrease in diameter and VFmean of the abdominal aorta and end-diastolic blood flow velocity of the left common carotid artery and an increase in peak systolic blood flow velocity and RI of the left common carotid artery. Also, MAP, HR, and body temperature decreased significantly after injections.

Conclusions and Clinical Relevance—Fentanyl injections induced a short-term decrease of vessel diameter in the abdominal aorta and increased resistance in the distal distribution area of the left common carotid artery. Results revealed decreases in MAP, HR, and body temperature, with an increasing effect after the third bolus injection, which indicated a cumulative drug effect.
Guest Editor's Introduction
Authors: OMRI MOHAMED-SALAH
Published: March 2009

The present themed issue of Comparative Critical Studies presents both specialist readers as well as comparatists less familiar with Islamic literatures and cultures with a representative array of critical articles and authorial pronouncements regarding the role of the novel in a grouping of literary traditions in which this genre is perceived as new or foreign, or both new and foreign. It attempts to read across Arabic, Persian, Urdu and Turkish traditions comparatively as well as in their relationship to Western literatures, breaking away from the dominant practice in comparative literature which tends to privilege the West-East paradigm. In the process the issue also hopes to introduce comparatists to the tools and methodology of Area Studies specialists, heeding recent debate about the collaborative task these two fields could and should engage in. Gayatri Chakravorty Spivak has recently called for aligning comparative literature with Area Studies, while Franco Moretti has spoken of a division of labour between the two.
Factors Associated with Higher Body Mass Index, Weight Concern, and Weight Gain in a Multinational Cohort Study of Smokers Intending to Quit
Authors: Aubin Henri-Jean , Berlin Ivan , Smadja Elisheva , West Robert
Published: March 2009

The ATTEMPT cohort study is multi-national, longitudinal study of smokers intending to quit recruited in the U.S.A., Canada, U.K. and France. Data on demographics, medical history, body mass index (BMI), weight concerns and smoking status were collected at baseline and after six months. A total of 2,009 subjects provided data at baseline and 1,303 at six months. High baseline BMI was associated with recent quit attempts, high weight concerns and high cigarette consumption. Weight gain was associated with low income, being single and number of cigarette-free days, but not with baseline weight concerns and confidence in preventing weight gain. Quit attempts were more frequent in subjects with a high baseline BMI and low weight concerns.
The Role of Disordered Ribosomal Protein Extensions in the Early Steps of Eubacterial 50 S Ribosomal Subunit Assembly
Authors: Timsit Youri , Acosta Zahir , Allemand Frédéric , Chiaruttini Claude , Springer Mathias
Published: March 2009

Although during the past decade research has shown the functional importance of disorder in proteins, many of the structural and dynamics properties of intrinsically unstructured proteins (IUPs) remain to be elucidated. This review is focused on the role of the extensions of the ribosomal proteins in the early steps of the assembly of the eubacterial 50 S subunit. The recent crystallographic structures of the ribosomal particles have revealed the picture of a complex assembly pathway that condenses the rRNA and the ribosomal proteins into active ribosomes. However, little is know about the molecular mechanisms of this process. It is thought that the long basic r-protein extensions that penetrate deeply into the subunit cores play a key role through disorder-order transitions and/or co-folding mechanisms. A current view is that such structural transitions may facilitate the proper rRNA folding. In this paper, the structures of the proteins L3, L4, L13, L20, L22 and L24 that have been experimentally found to be essential for the first steps of ribosome assembly have been compared. On the basis of their structural and dynamics properties, three categories of extensions have been identified. Each of them seems to play a distinct function. Among them, only the coil-helix transition that occurs in a phylogenetically conserved cluster of basic residues of the L20 extension appears to be strictly required for the large subunit assembly in eubacteria. The role of a helix-coil transitions in 23 S RNA folding is discussed in the light of the calcium binding protein calmodulin that shares many structural and dynamics properties with L20.
Model Protocells from Single-Chain Lipids
Authors: Mansy Sheref S.
Published: March 2009

Significant progress has been made in the construction of laboratory models of protocells. Most frequently the developed vesicle systems utilize single-chain lipids rather than the double-chain lipids typically found in biological membranes. Although single-chain lipids yield less robust vesicles, their dynamic characteristics are highly exploitable for protocellular functions. Herein the advantages of using single-chain lipids in the construction of protocells are discussed.
Chaperonin Structure - The Large Multi-Subunit Protein Complex
Authors: Banach Mateusz , Stąpor Katarzyna , Roterman Irena
Published: March 2009

The multi sub-unit protein structure representing the chaperonins group is analyzed with respect to its hydrophobicity distribution. The proteins of this group assist protein folding supported by ATP. The specific axial symmetry GroEL structure (two rings of seven units stacked back to back - 524 aa each) and the GroES (single ring of seven units - 97 aa each) polypeptide chains are analyzed using the hydrophobicity distribution expressed as excess/deficiency all over the molecule to search for structure-to-function relationships. The empirically observed distribution of hydrophobic residues is confronted with the theoretical one representing the idealized hydrophobic core with hydrophilic residues exposure on the surface. The observed discrepancy between these two distributions seems to be aim-oriented, determining the structure-to-function relation. The hydrophobic force field structure generated by the chaperonin capsule is presented. Its possible influence on substrate folding is suggested.
The Contribution of the Elastic Reaction is Severely Underestimated in Studies on Myofibril Contraction
Authors: Grazi Enrico , Pozzati Sara
Published: March 2009

We have considered the Huxley-Simmons manoeuvre. On the assumption that the quick release is an elastic process and on the basis of the isometric tension and of the stiffness of the muscle fibre we calculated that the spontaneous release of the fibre requires ~43 μs, which is much faster than the observed release, ~180 μs. We concluded that the observed quick release is a guided process. After proper selection of the mass and of the stiffness of the system we mimicked the early recovery and noticed that most of the energy required to accomplish the early recovery is supplied by the kinetic energy accumulated during the course of the quick release. We computed that the frequency of the working strokes in the half sarcomere was between 4×106 and 40×106 s-1. This is not to say that the ATPase rate constants are accumulative but only that the overall frequency of the working strokes in the half saromere is many orders of magnitude faster than the average ATPase rate constant. With this frequency no part of the Huxley-Simmons manoeuvre, quick release included, escapes the control of the working stroke. This means also that there is no reason to take the early recovery as an indication of the length of the working stroke.
Effect of [10]-Gingerol on [Ca2+]i and Cell Death in Human Colorectal Cancer Cells
Authors: Chen Chung-Yi , Li Yi-Wen , Kuo Soong-Yu
Published: March 2009

The effect of [10]-gingerol on cytosol free Ca2+ concentration ([Ca2+]i) and viability is large unknown. This study examines the early signaling effects of [10]-gingerol on human colorectal cancer cells. It was found that this compound caused a slow and sustained rise of [Ca2+]i in a concentration-dependent manner. [10]-Gingerol also induced a [Ca2+]i rise when extracellular Ca2+ was removed, but the magnitude was reduced by 38%. In a Ca2+-free medium, the [10]-gingerol-induced [Ca2+]i rise was partially abolished by depleting stored Ca2+ with thapsigargin (an endoplasmic reticulum Ca2+ pump inhibitor). The elevation of [10]-gingerol-caused [Ca2+]i in a Ca2+-containing medium was not affected by modulation of protein kinase C activity. The [10]-gingerol-induced Ca2+ influx was insensitive to L-type Ca2+ channel blockers. At concentrations of 10-100 mM, [10]-gingerol killed cells in a concentration-dependent manner. These findings suggest that [10]-gingerol induces [Ca2+]i rise by causing Ca2+ release from the endoplasmic reticulum and Ca2+ influx from non-L-type Ca2+ channels in SW480 cancer cells.
CARDINAL APPROXIMATION OF FUNCTIONS BY SPLINES ON AN INTERVAL
Authors: Vainikko Gennadi
Published: March 2009

The cardinal interpolant of functions on the real line by splines is determined by certain formula free of solving large or infinite systems. We apply this formula to functions given on the interval [0,1] introducing special extensions of functions from [0,1] into the real line which maintains the optimal error estimates. The computation of the parameters determining the interpolant costs O(n log n) operations.
NUMERICAL SOLUTION OF A MODEL FOR BRAIN CANCER PROGRESSION AFTER THERAPY
Authors: Jackiewicz Zdzislaw , Kuang Yang , Thalhauser Craig , Zubik-Kowal Barbara
Published: March 2009

We present a numerical scheme used to investigate a mathematical model of tumor growth which incorporates multiple disparate timescales. We simulate the model with different initial data. The initial conditions explored herein correspond to a small remnant of tumor tissue left after surgical resection. Our results indicate that tumor regrowth begins at the pre‐surgery tumor‐healthy tissue interface and penetrates back into the original tumor area. This growth is rate‐limited by the reformation of the tumor vascular network.
NUMERICAL SOLUTION OF VOLTERRA INTEGRAL EQUATIONS WITH WEAKLY SINGULAR KERNELS WHICH MAY HAVE A BOUNDARY SINGULARITY
Authors: Kolk Marek , Pedas Arvet
Published: March 2009

We propose a piecewise polynomial collocation method for solving linear Volterra integral equations of the second kind with kernels which, in addition to a weak diagonal singularity, may have a weak boundary singularity. Global convergence estimates are derived and a collection of numerical results is given.
Bearing capacity evaluation of rubblized concrete pavements
Authors: Thenoux G. , González M.
Published: March 2009

The paper presents the findings of a research work performed on a real scale concrete pavement project where Rubblizing technology was used for its structural rehabilitation. Rubblizing may be defined as a fracture technique in which a concrete pavement slab is transformed in a granular base with a very high Modulus. This technique, fractures the concrete slab in angular pieces by using a concentrated dynamic load of low amplitude and high frequency. The research work was based on field study on the rehabilitation of 5 km motorway. The structural evaluations where made, before, during and after one year construction. Measurements and site evaluation where made by using DCP, Light Weight Deflectometer and FWD (on top of asphalt layer) and excavating inside pits. The structural capacity of the Rubblized layer was evaluated through theoretical analysis. Because of the anisotropic properties of the Rubblized layer the results are presented using AASHTO structural layer coefficient. The structural layer coefficients recommended are between the range of 0.25 and 0.30 for concrete slabs with thickness grater than 220 mm.
Preparation of Polycarbosilane Using a Catalytic Process and Its Practical Uses
Authors: Kim Y. , Shin Dong Geun , Kim Hyung Rae , Park Hong Sik , Riu Doh Hyung
Published: March 2009

Polycarbosilane is the most typical polymeric precursor for SiC ceramic. In this study, liquid type polycarbosilane was synthesized from polydimethylsilane in the presence of solid acid catalyst at 350oC. The molecular weights of the polycarbosilane were ranged between 350 and 530. Synthesized polycarbosilane was characterized with 29Si Solid NMR, FT-IR and GPC analysis. The synthesized polycarbosilane can be used as a good organometallic precursor for SiC coating via chemical vapor deposition or spin coating.
Injectable Supramolecular Hydrogels Self-Assembled by Polymers and Cyclodextrins for Controlled Drug Delivery
Authors: Li Jun , Li Xu , Ni Xiping , Wang Xin , Li Hongzhe , Zhou Zhi Han
Published: March 2009

Of many polymeric biomaterials, hydrogels are of special importance because of their favorable biocompatibility and pertinence in delivering delicate bioactive agents such as proteins. Physical hydrogels have attracted much attention for controlled drug delivery because of the mild and aqueous conditions involved in trapping bioactive agents. This paper reviews our recent progress on developing a new class of physical hydrogels based on the supramolecular self-assembly between cyclodextrins and bioabsorbable poly(ethylene oxide) (PEO) or its copolymers. Being thixotropic, the hydrogels can be injected through needles and applied as injectable drug delivery systems. The properties of the hydrogels also can be fine-tuned with triblock copolymers where PEO segments flank hydrophobic or biodegradable segments in the middle.
In Vivo Chondrogenesis of BMSCs at Non-Chondrogenesis Site by Co-Transplantation of BMSCs and Chondrocytes with Pluronic as Biomaterial
Authors: Zhou Guang Dong , Liu Wei , Cui Lei , Cao Yi Lin
Published: March 2009

Bone Marrow Stromal Cells (BMSCs) have chondrogenesis potential if chondrogenic environments or factors are provided. This study tests the hypothesis that chondrocytes can promote BMSC chondrogenesis at non-chondrogensis site. Porcine BMSCs and auricular chondrocytes were mixed at different ratios and 2.5×107 mixed cells were resuspended in 0.5 ml 30％ Pluronic, and then the mixture was injected into nude mice subcutaneously as experimental groups. Chondrocytes or BMSCs at the same cell number were mixed with 0.5 ml Pluronic and injected respectively as controls. 2.5×107 chondrocytes were mixed and injected as low concentration chondrocyte control. 8 weeks later, all specimens in experimental groups and chondrocyte group formed mature cartilage with abundant collagen II expression. Mature lacuna structures and metachromatic matrices were also observed in these specimens with the same level of GAG contents. Average wet weight of specimens in experimental groups was over 70% of that in chondrocyte group. In contrast, specimens in BMSC group showed mainly fibrous tissue. Only a small amount of cartilage was formed in specimens of low concentration chondrocyte group and the average wet weight was below 30% of that in chondrocyte group. These results demonstrate that chondrocytes can provide chondrogenic microenvironment and thus promote in vivo chondrogenesis of BMSCs at non-chondrogenesis sites. It also indicates that Pluronic is an ideal injectable biomaterial for cartilage tissue engineering.
A 3D Profile Parallel Detecting System Based on Differential Confocal Microscopy
Authors: Wang Y.H. , Yu X.F. , Fei Ye Tai
Published: March 2009

Based on the differential confocal microscopy principle, a non-scanning 3D profile detecting system is proposed. A 2D light source array produced by micro-optic components is used to form a parallel micro-confocal system. The whole field detecting of the measuring plane is realized. The reflected light beam is divided into two paths. Two CCD cameras work together to detect the facula array in a differential arrangement. A differential algorithm of facula intensity is used. The noise and the shift of light source can be avoided effectively. Using the linearity characteristic of the differential confocal system, the high axial resolution is achieved at a larger sampling interval. The measuring efficiency and accuracy can be increased. The construction and working principle of the 3D parallel detecting system and the 3D profile reconstruction method are investigated. Experiment results agree with the ones of theory analysis. It indicates that the differential method is applicable for non-scanning 3D profile detection.
Excitation of X-Rays Using Polarized LiNbO3 Single Crystal
Authors: Fukao Shinji , Kondo Jun , Nakanishi Yoshikazu , Ito Yoshiaki , Yoshikado Shinzo
Published: March 2009

The radiation of X-rays using the electric charge generated by a temperature change of a LiNbO3 single crystal has been investigated. When the LiNbO3 single crystal was placed in a conductive cylindrical pipe made of graphite, aluminum or copper, the photon flux of the radiated X-rays was dependent on the type of conductive material used. Depending on the type of materials on which the crystal was placed, the photon flux of the radiated X-rays increased with decreasing work function of the material.
Development of New Preparation Method for nm-Sized Barium Titanate Particles
Authors: Nishiyama Michiyasu , Hoshina Takuya , Kakemoto Hirofumi , Tsurumi Takaaki , Wada Satoshi
Published: March 2009

A new method for ultrafine barium titanate (BaTiO3) particles with diameters of around 5 nm is proposed. In this method, barium titanyl oxalate aqua solution with low concentration below 10-3 mol/l was used as the starting material. The droplets with a size below 3 μm were atomized with an ultrasonic vibrator, dried and thermally decomposed at higher temperatures over 300°C. In the preparation of the BaTiO3 particles, there were two parameters such as thermal decomposition temperature and precursor solution concentration. Therefore, various particles were prepared by changing these parameters. Finally, non-aggregated nm-sized BaTiO3 particles with an average diameter of 5.2 nm, despite wide size distribution from 2 to 20 nm, were prepared by using the precursor solution with 10-6 mol/l.
Synthesis and Characterization of Barium Titanate Nano-Powders by the Hydrothermal Process
Authors: Tokita Kouji , Sato Shigeki
Published: March 2009

Barium titanate (BaTiO3) nano-particles with high crystalinity were synthesized by hydrothermal process using Ba(OH)2·8H2O and TiO2 as source materials. The average size of the synthesized BaTiO3 particles decreased as the TiO2 particle size decreased. The amount of hydroxide ions incorporated into the perovskite lattice decreased as the BaTiO3 particle size increased and then became constant above 50 nm. Moreover, the ratio of the c- to a-axis length increased when the BaTiO3 particle size was above 50 nm. Sintered ceramics with a grain size smaller than 100 nm were obtained by using highly crystallized hydrothermal BaTiO3 particles.
Effect of High Temperature on Concrete: A Literature Review
Authors: Peng Gai Fei , Chan Sammy Yin Nin , Song Qi Ming , Yi Quan Xin
Published: March 2009

This paper presents a review on the effect of fire on concrete, citing 43 references. It was found that most of them are on the behavior of concrete under high temperature conditions more or less different from the standard fire condition. The problem of spalling, which high-strength concrete encounters when exposed to fire, is especially urgent to solve. Since the literature on the behavior of concrete under fire conditions is very limited, the literature even under elevated temperature has to be used as a part of the base of further research. The further research needs urgently to be carried out under the standard fire condition. Residual mechanical properties reported in most previous literature might be overestimated, where natural cooling was usually employed. Proper evaluation of fire resistance of concrete needs more experimental data obtained under various cooling regimes such as water spraying or water quenching.
Influence of Shrinkage Reduce Agent on Early Age Autogenous Shrinkage of Concrete
Authors: Qian Xiao Qian , Meng Tao , Zhan Shu Lin , Fang Min Hui , Qian Kuang Liang
Published: March 2009

Based on designed and manufactured test equipment of concrete early age shrinkage, the influence of shrinkage reduce agent (SRA) on early age autogenous shrinkage of concrete was researched. The test results show that early age autogenous shrinkage of concrete was reduced with SRA added and the shrinkage-reducing ratio increased with concrete strength grade heightened. SRA could also greatly reduce early age autogenous shrinkage of concrete added with pulverized ly ash or slag. Superplasticizer would increse early age autogenous shrinkage of concrete, and the shrinkage was larger than those without superplasticizer, even the SRA mixed into. Furthermore, early age curing should be enhanced for concrete with superplasticizer.
Synthesis and Properties of Polycarboxylate-Type High Range Water-Reducer
Authors: Li Chong Zhi , Feng Nai Qian , Han Xian Fu , Lu Lai-Jun
Published: March 2009

A series of polycarboxylate-type water-reducers (MPCs) had been developed and tested. Through molecular design, macromers of polyethylene glycol unsaturated carboxylic esters, and other derivative of unsaturated vinyl monomer containing the carboxylic groups，sulphonic groups， graft groups of alkyleneglycol was introduced as the chemical structure unit of MPCs. The copolymers MPC-2 contained long and short PEO chains and ionic groups, possessed a high dispersing and good slump retaining behavior. Therefore, MPCs can be used as high range water-reducers to prepare high-flowing concrete, high-strength high performance concrete and high-durability concrete.
Microgrinding of Nanostructured Carbide Coatings: Ground Surface and Subsurface Damage Observations
Authors: Ren Y.H. , Zhou Zhi Xiong , Deng Zhao Hui
Published: March 2009

Surface microgrinding of the nanostructured WC/12Co coatings have been undertaken with diamond wheels under various conditions. Nondestructive and destructive approaches were utilized to assess damage in ground nanostructured coatings. Different surface and subsurface configurations were observed by scanning electron microscopy. This paper investigates the effects of microgrinding conditions on damage formation in the surface and subsurface layers of the ground nanostructured WC/12Co coatings. And the material-removal mechanism has been discussed.
Resin Bonded CBN Grinding Wheel Dressing by Laser — Simulation and Experiment
Authors: Chen Ming , Ma Y.P. , Liu Gang , Xiang Dao Hui , Sun Fang Hong
Published: March 2009

Due to the large difference in thermal properties of the resin and the abrasive grits, the laser-assisted dressing technology is of great interest for grinding wheel preparation. From a viewpoint of thermal induced material removal mechanism, a numerical method was presented to simulate the laser dressing process. The numerical simulation results could reveal the relations between the laser parameters and the groove formation. The overlap coefficient was introduced for practical application. Simulation for the variation of the number of active grinding points was also made for non-uniform wheel topography. Based on the numerical modeling, the suitable grinding^wheel surface topography can be achieved through the laser-assisted dressing technology. The comprehensive researches on the laser-assisted dressing process control, grinding wheel topography reconfiguration by 3D laser scanning technology and analyses of grinding temperature were made.
A series of grinding tests with the laser-assisted dressed grinding wheel and mechanically dressed grinding wheel were conducted for comparison. The results proved the feasibility of laser-assisted dressing for resin bonded superabrasive grinding wheels and revealed the importance of choosing appropriate laser dressing parameters.
Injection Molding Process of Mg Alloy for Thin Plate
Authors: Kang Tae Ho , Kim In Kwan , Kim Young Soo
Published: March 2009

Magnesium alloys are very attractive materials for applying to the development of automobile parts or electric goods where a lightweight and a higher strength need. Due to higher ratio of strength vs. weight and stiffness vs. weight, various magnesium alloys are well applied in much weight saving design applications though an extrusion or a die-casting process. However, for the requisites of higher strength and weight savings, some new fabrication processes has been and it can be realized though the aid of the injection molding technology. To obtain the parametric data based upon the injection molding process, various experiments were executed for AZ91D magnesium alloy. This research proposes the optimum condition of an injection temperature, the first and the second pressure. The process was lined-up successfully often changing the injection unit and the hydraulic unit from the conventional plastic injection machine.
Mechanical Properties of Zirconia/Alumina Nano-Composite after Soaking in Various Water-Based Conditions
Authors: Ban Seiji , Nawa Masahiro , Suehiro Y. , Nakanishi H.
Published: March 2009

Yttria stabilized tetragonal zirconia polycrystals (Y-TZP) have been applied to dental crown and bridges. Whereas, to further improve its mechanical strength, the zirconia/alumina nano-composite stabilized with cerium oxide (Ce-TZP/Al2O3 nano-composite) was developed. In the present study, biaxial flexure strength, fracture toughness and hardness were determined before and after soaking in water-based conditions and the possibility of application to all ceramic dental
restorations was discussed. In comparison to Y-TZP, Ce-TZP/Al2O3 nano-composite has quite high flexure strength and fracture toughness along with satisfied durability for LTAD in various water-based conditions encountered in dentistry. Therefore, it is concluded that the nano-composite can be safely applied to dental restoratives such as all-ceramic bridges.
Hip Simulator Study of Ceramic-Ceramic and Ceramic-PE-Couplings with Different Head Diameters
Authors: Oberbach Thomas , Begand Sabine , Glien Wilfried
Published: March 2009

The contact conditions and the resulting contact stresses for ceramic on ceramic pairings with diameter 28, 32 and 36mm were determined. A hip simulator according ISO 14242 was used to measure the wear behaviour of these hard – hard couplings in comparison with the common hard – soft pairing ceramic on polyethylene. It was found that there isn’t a significant dependence of the wear behaviour from articulation diameter for ceramic on ceramic but a strong increase of polyethylene wear with larger hip joint heads.
Comparative Histological Studies on Existing and Not Existing HA Granules in the Same Hip in a Modified Cementing Technique Using HA Granules
Authors: Inoue Hiroko , Oonishi Hironobu , Kim Seok Cheol , Fujita Hiroshi , Doiguchi Yuichi , Oomamiuda Koichi
Published: March 2009

We evaluated the differences of histological findings of the retrieved specimens from the different areas in the same hip with interposing HA granules and without interposing HA granules between the bone and bone cement interface. In the area existing HA, bone ingrowth into the spaces of HA granules was very dense and a thick bone layer with HA granules contacted around the bone
cement. In the area not-existing HA, bone formation at the base was seen poorly and bone formation at the area adjacent to the bone cement was not seen.
The Effects of Autograft and Calcium Carbonate on the Periodontal Healing of 3-Wall Intrabony Defects in Dogs
Authors: Kim Tae Gyun , Jung Ui Won , Kim C.S. , Lee Yong Keun , Choi Seong Ho , Cho Kyoo Sung , Kim Chong Kwan , Chai Jung Kiu
Published: March 2009

This study evaluated periodontal repair and biomaterial reaction following implantation of a calcium carbonate and autogenous bone on the regeneration of 3-wall intrabony defects in the beagle dogs. The surgical control group received a flap operation only, while the experimental group I was treated with a calcium carbonate and the experimental group II was treated with autograft. The subjects were sacrificed 8 weeks after surgery and a comparative histometric analysis was done. No root resorption or ankylosis were observed in the experimental group. ANOVA post Hoc test showed that the experimental group II produced statistically significant higher gain in connective tissue adhesion, new cementum regeneration and new bone formation. These results suggest that the use of autograft in 3-wall intrabony defects has a significant effect on new cementum and new bone formation height.
Preparation of Submicron Biphasic α-TCP/HA Powders
Authors: Pan Li Li , Li Yan Bao , Weng Wen Jian , Cheng Kui , Song Chen Lu , Du Pi Yi , Zhao Gao Ling , Shen Ge , Wang Jian Xun , Han Gao Rong
Published: March 2009

An amorphous calcium phosphate precursor way was utilized to prepare submicron
biphasic α-tricalcium phosphate (TCP)/hydroxyapatite (HA) powders. The results showed that the addition of carbonate during the precipitation reaction could eventually lead to the formation of HA phase in the resulting powders, and even determine the relative content of HA to the range from 0 percent (pure α-TCP) to 100 percent (pure HA). Similarly, the particle size of the resulting biphasic
powders depended on the carbonate content, ranging from 100nm to 500nm. The biphasic Ca phosphate with tailored α-TCP/HA ratio could be a new combination of calcium phosphate for promoting early bone formation.
A Study on the Bioactivity of Nano-Titania/Hydroxyapatite Composite
Authors: Yang Bang Cheng , Yu Qi Feng , Chen Ji Yong , Zhang Xing Dong
Published: March 2009

The bioactivity of a composite of titania and hydroxyapatite was studied in vitro in this paper. After the titania ceramics was added 10% HA, it could induce apatite formation in simulated body fluid in 2d, while the pure titania ceramics could not induced apatite formation even after 14d. After the composite of titania and HA was subjected to alkali-heat treatment, it has a faster speed for apatite formation in SBF than the composite without treatment. When the osteoblast was cultured on the materials, the amount of osteoblasts attaching on the composite was more than that on the pure titania ceramics. It has the most osteoblasts cells on the composite subjected to alkali-heat treatment. These results showed that the composite of titania and HA is a bioactive materials, while the alkali-heat treatment could improved the bioactivity of this composite.
Mapping the Microstructure–Property Relationships in Cortical Bone
Authors: Low It Meng , Pang Wei Kong , Davies Ian J.
Published: March 2009

Structure-property relationships in bovine cortical bone have been characterised using grazing-incidence synchrotron radiation diffraction, Vickers indentation and mechanical testing. Depth profiling results indicated the existence of distinct gradual changes in crystal disorder, phase abundance, and texture of hydroxyapatite whilst the crystallite size was depth-independent.
Adhesion and Proliferation of Chondrocytes on Nano- HA/PDLLA Scaffolds for Bone Tissue Engineering
Authors: Chen P.P. , Zhang Sheng Min , Cheng L. , Huang S.L. , Liu Jian , Zhou W. , Gong H. , Luo Q.M.
Published: March 2009

In this paper, three different scale HA/PDLLA porous scaffolds, nano-HA/PDLLA,
micro-HA/PDLLA and pure PDLLA were successfully fabricated using solvent casting/particulate leaching method. Chondrocytes adhesion and proliferation on these scaffolds were investigated. In detail, the cells attachment rate and proliferation on nano-HA/PDLLA, micro-HA/PDLLA and pure
PDLLA were quantitatively evaluated by cytometry. The interaction between the scaffolds and chondrocytes were observed by optical microscope with HE staining and FE-SEM. The results exhibited that nano-HA/PDLLA scaffold has a modified cell adhesion property, and cells on the nano-scaffold grow much better both in biological and morphological characteristics than on the micro-HA/PDLLA and pure PDLLA scaffolds. This work suggested that nano-HA/PDLLA
composite scaffold can significantly improved cell adhesion and proliferation tendency with the existing of nano-effects，and could be used as a potential scaffold material for bone defect repair.
Preparation, Physical and Mechanical Characterization of Montmorillonite/Polyethylene Nanocomposites
Authors: Pettarin V. , Rodriguez Pita Victor Jayme Roget , Valenzuela-Díaz Francisco Rolando , Moschiar S. , Fasce L. , Seltzer R. , Lopes Dias Marcos , Frontini P.
Published: March 2009

In this paper, we report the preparation of polyethylene composites with organically
modified montmorillonite. Three different Na+-montmorillonites were modified in order to obtain organoclays and two grades of high-density polyethylene were used as composite matrices. All composites were prepared by melt blending, and their physical and mechanical properties were thoroughly characterized. The extent of clay platelet exfoliation in the composites was confirmed by X-ray diffraction (XRD). Mechanical properties under static and impact conditions were
evaluated to assess the influence of the reinforcement on the properties of polyethylene.
Influence of Electrostatic Interactions in the Deposit on the Electrical Field Strength during Electrophoretic Deposition
Authors: Anné Guy , Neirinck Bram , Vanmeensel Kim , Van der Biest Omer , Vleugels Jef
Published: March 2009

A model was developed to explain the magnitude of the potential drop over the deposit
for non-conductive powders during electrophoretic deposition (EPD). The magnitude of the
potential drop over the deposit is explained in terms of a reduced ion transport through the deposit,
as controlled by the pore potential that is related to the thickness of the electrostatic double layer
relative to the pore radius and the magnitude of the surface potential of the powder particles. This
model was validated for EPD of Al2O3 powder from ethanol-based suspensions with HNO3
addition. The specific resistivity of the deposit could be related to the calculated potential in the
pores of the deposit.
Microstructures and Mechanical Properties of Nano-Structured Aluminum Fabricated by Accumulative Roll-Bonding Using Different Rolling Methods
Authors: Lee Seong Hee , Sakai Tetsuo , Lee Chung Hyo , Choa Yong Ho
Published: March 2009

Nano-structured aluminum was fabricated by accumulative roll-bonding (ARB)
process using different rolling methods. One is the ARB using conventional rolling (CR) in
which the speed of two rolls (3.0m/min) was equal to each other. The other is the ARB using
differential speed rolling (DSR) in which the speed of two rolls is different to each other. The
roll peripheral speed of one roll was 2.0m/min and that of another roll was 3.6m/min. The roll
speed ratio was kept at 1.8. The ARB was conducted up to 6 cycles at ambient temperature
without lubrication. In both cases, the ultrafine grains were developed in the samples. The grains
formed by the DSR-ARB were more equiaxed and finer than those produced by the CR-ARB.
Tensile strength of the DSR-ARB processed sample was superior to that of the CR-ARB
processed one. The elongation was not affected significantly by the number of ARB cycles in
both cases. Texture analysis demonstrated that the shear strain, in the case of DSR-ARB, was
introduced into the center of thickness. It was concluded that the DSR-ARB process was more
effective for grain refinement and strengthening than the CR-ARB process.
High Temperature Characteristics of Melt Growth Composites and Their Application to Ultra High Efficiency Gas Turbine Components
Authors: Waku Yoshiharu
Published: March 2009

Much attention has been paid to unidirectionally solidified ceramic composites as a candidate for a high-temperature structural material. We have recently developed eutectic composites, which are named as Melt Growth Composites (MGCs). The binary MGCs (Al2O3/YAG and Al2O3/GAP binary systems) have a novel microstructure, in which continuous networks of single-crystal Al2O3 phases and single-crystal oxide compounds (YAG or GAP) interpenetrate without grain boundaries. Therefore, the MGCs have excellent high-temperature strength characteristics, creep resistance, superior oxidation resistance and thermal stability in an air atmosphere at very high temperatures. Manufacturing processes for the MGCs are being examined under a Japanese national project, scheduled from 2001 - 2005. To achieve higher thermal efficiency for gas turbine systems, a bowed stacking nozzle vane has been fabricated on an experimental basis.
Processing and Property Evaluation of Alumina Aerogel Based Ceramic Nanocomposites
Authors: Yamuna A. , Tajiri K. , Honda Sawao , Hashimoto Shinobu , Awaji Hideo
Published: March 2009

Aerogels are sol-gel derived mesoporous materials with low apparent density and large specific surface areas. The mechanical property evaluation of pulsed electric current sintered (PECS) alumina and its composite aerogels with nanosized metallic dispersions is an area of interest. In the present work alumina, alumina-copper, alumina-nickel, alumina-cobalt and alumina-tungsten aerogels have been synthesized by super critical drying of respective the sols. The samples were pre-calcined under controlled sintering conditions and pulsed electric current sintered at two different temperatures: (1) at a lower sintering temperature with short residence time (1250°C for 5min) and (2) at a high temperature with prolonged soaking time (1450°C for 30 min) and their mechanical properties were evaluated.
A Technique for Permittivity Measurement of Ceramic Powders at Microwave Frequencies
Authors: Ehata Katsufumi , Che Shenglei , Sakamoto Norimasa
Published: March 2009

Details of a new technique for the permittivity measurement of ceramic powders at microwave
frequencies are described. Permittivity of a powder is calculated from the permittivity of liquid
medium and that of the slurry made from the liquid medium and the powder. Measured
permittivities of BaNd2Ti4O12 ceramic powders vary by processing conditions of the powders. This
result is consistent with permittivities of composite substrates made from these powders and a
thermosetting resin.
Studies about the Influence Factors on Ultrasonic Velocity of Domestic Red Pine
Authors: Han So Ra , Park Chun Young , Eom Young Geun , Lee Jun Jae
Published: March 2009

This research was carried out to grasp the factors influencing to the ultrasonic velocity to
improve the efficiency of the ultrasonic wave test using as the method of NDE of wood. However, it
was difficult to detect the defect of wood accurately, because ultrasonic velocity is influenced by
various factors. So, some effect factors, which were not concerned with decay, were confirmed at
first. Therefore, in this research, we tried to find the factors which affect on the natural characters and
the ultrasonic velocity at decayed wood, additionally, we tried an anatomic experiment and analyze.
As a result of research, the velocity at radial direction was faster than that at tangential direction and
the ultrasonic velocity at immature wood and reaction wood was slower than that at normal wood.
And the ultrasonic velocity was more the slower at bigger the length of decay and reduction of weight.
A Wall Thinning Detection and Quantification Based on Guided Wave Mode Conversion Features
Authors: Cho Youn Ho , Oh Won Deok , Lee Joon Hyun
Published: March 2009

This study presents a feasibility of using guided waves for a long-range inspection of pipe
through investigation of mode conversion and scattering pattern from edge and wall-thinning in a
steel pipe. Phase and group velocity dispersion curves for reference modes of pipes are illustrated for
theoretical analyses. Predicted modes could be successfully generated by controlling frequency,
receiver angle and wavelength. The dispersive characteristics of the modes from and edge
wall-thinning are compared and analyzed respectively. The mode conversion characteristics are
distinct depending on dispersive pattern of modes. Experimental feasibility study on the guided waves
was carried out to explore wall thinning part in pipe for data calibration of a long range pipe
monitoring by comb transducer and laser.
Seismic Performance of RC Structures Using an Improved Inelastic Analysis Method
Authors: Kim Jin Ho , Yang Sin Chu
Published: March 2009

Inelastic analysis procedures may be useful as a first approximation for the seismic
response of a structure. The Capacity Diagram Method procedure, which is based on R--T
(Reduction-ductility-Period) relationships, is investigated to compare with the modified CDM
procedure. The CDM procedure is applied to the example model, which is moment resistant RC
frame. Two seismic hazard categories having exceedance probabilities of 2% in 50 years and 10%
in 50 years earthquake ground motions have been selected for evaluating the performance of the
example model. The performance objective of the example model is represented by the combination
of a structural performance level and an earthquake hazard level.
Numerical Simulation on Fast Crack Propagation in a Bi-Material Involving interfaces under Dynamic Loading
Authors: Wang Yue Sheng , Lei Jun , Gross Dietmar
Published: March 2009

The paper considers a bi-material with a crack propagating rapidly, penetrating or
deflecting at the interface under dynamic loading. The hybrid time-domain boundary element method,
together with the multi-region technique, is applied to simulate the dynamic process of propagation
and penetration or deflection of the crack. Moving of the crack tip in the matrix, penetration and
deflection of the crack at the interface, and propagation of the crack along the interface are controlled
by criteria developed from the quasi-static ones. A bi-material rectangular plate with an edged crack
under impact loading is computed and compared with the photoelastic experiments. Good agreement
between numerical and experimental results implies that the present boundary element numerical
method can provide an excellent simulation for the dynamic crack propagation in a bi-material
involving interfaces.