bluuebunny/crossref_metadata_2025 huggingface dataset:
Study on Automatic Measurement of Valve Orifice Characteristic Based on Pneumatic Flow Method
Authors: Liu J. , Wang Guang Lin , Xu N.
Published: March 2009

Spool valve orifice flow characteristic of servo valve plays an important role in the spool
valve overlap measurement and manufacturing quality analysis of servo valve. The liner segment of
flow characteristic curve could be used to calculate the overlap, and the non-linear segment could be
used to evaluate the manufacturing quality of servo valve. This paper analyzed the valve orifice
characteristic measurement based on the pneumatic flow method in detail, developed an automatic
pneumatic measurement apparatus for valve orifice characteristic and spool valve overlap based on
the thermal mass flow sensor AWM2300, verified the measurement accuracy and non-repeated error
of this apparatus, and adopted the overlap as investigated object to contrast the measurement results
by pneumatic flow method with by pneumatic pressure method. The non-repeated error of overlap
measurement by pneumatic flow method did not exceed ±0.5(m, and the experimental results
indicated that the automatic pneumatic flow measurement can excellently satisfy the actual
requirement in the production of servo valve.
Theoretical Simulation of Temperature Field of Coaxial Powder Stream in Laser Cladding
Authors: Dong Z. , Yang Xi Chen
Published: March 2009

Theoretical models of temperature field are presented from Beer-Lambert law. This paper
uses Beer-Lambert law to calculate powder flow on the absorption of energy and applies the law of
the conservation of the energy to calculate the temperature of powder stream. This paper analyzes the
effect of the various factors on the temperature field of powder flow. Temperature field of powder
stream is measured by CCD camera. Finally the comparison of the theoretical results and the
experimental results indicates the accuracy of the theoretical calculation.
On Three Axes Ganged NC Grinding Machine with Ganged Revolving Spindle
Authors: Zhang Zi Qiang , Chen Shao Bo , Zheng Zhi Dan
Published: March 2009

The different uses of NC grinding machine with ganged revolving spindle and the
requirements to NC grinding machine for several special uses are discussed. A multifunctional three
axes ganged NC grinding machine with patent right is introduced. Its ganged revolving spindle is
changeable. Therefore it can meet the requirements of different uses. When the ganged revolving
spindle works as headstock spindle, the NC grinding machine can be used for machining cylindrical
cam, plate cam, noncircular shaft and so on. When the ganged revolving spindle works as a revolving
spindle of dresser, the NC grinding machine can be used for dressing form wheels with multifarious
curved generatrices accurately. With simple mechanism, wide flexibility and simple NC
programming, it is especially fit for laboratory use. A new-style NC dresser with invention patent
right is also introduced.
Telerobot Control System with Petri Net-Based Multi-Control Modes Transfer in Due Time
Authors: You Bo , Li Dong Jie , Qiu Jiang Yan
Published: March 2009

Man-machine cooperative teleoperation and multi-control modes transfer in due time are the key problems that the telerobot system must deal with. That is the intelligence of the operator and the robot in the system should be distributed appropriately according to the current task state. The current task state of the telerobot system should be evaluated to solve these problems. So the telerobot control system is built with current task state evaluation after analyzing system control modes. For the control modes transfer in due time, its Petri Net (PN) model is built and it is simulated with the Stateflow module of Matlab. Simulation results show the validity and rationality of the model.
Construction of Exterior Features for Tissue Engineering Scaffold with Defect Bone
Authors: Dai Chun Xiang , Fang M.L. , Hu Q.X.
Published: March 2009

Based on definitions of tissue engineering scaffold with defect bone, the constructing
method for its exterior features was presented. First the pixels of picture at defect area were filled up
and then the Boolean operations of filled pixels and original bone pixels were executed, and finally,
all the area of filled pixels was 3D reconstructed to obtain the exterior features of scaffold. The
3D-reconstruction idea of the exterior features of scaffold and related projection and Boolean
processes of model data for defect area were also analyzed.
Study on Dynamic Characteristics and Simulation of Plane Grinding System under Two-Dimensional Ultrasonic Vibration
Authors: Du Bao Yu , Zhao Bo
Published: March 2009

In this paper, the mathematical model with two associated coordinates is established for two-dimension ultrasonic vibration group system by impedance analysis, and natural frequency equation of 2D vibration system is deduced by which the influence of natural frequency change of individual components on the natural frequency of group system is analyzed. Amplitude-frequency characteristics of system were tested which verified the correctness of the theory. In simulation experiment on large plate under two-dimensional ultrasonic vibration grinding, superimposed tracks of a number of irregular ovals exist in vibrating plane, that is different from previous research that only one simply oval track exists in the vibrating plane apparently. The results supply a reliable theoretical and experimental basis for the further discussions on the abrasive removal mechanism under two-dimensional ultrasonic vibration.
Development of Automatic Measurement Platform for Servo Valve Nozzle Volume
Authors: Shao Dong Xiang , Cui T.Z. , Wang Guang Lin , Pan Xu Dong , Xing L.F.
Published: March 2009

This paper introduces an automatic measurement technology of electro-hydraulic servo
valve nozzle volume. Since there are several disadvantages of manual measurement in workplace,
develops a new kind of intelligent volume test platform which can adjust pressure and record data
automatically under constant oil temperature and match through computer. The outcome of the
nozzle match experiment in the end satisfies the operating requirements.
Wheel Velocity Analysis of a Rover with Six Wheels Independently Driven on Uneven Terrain
Authors: Dong Yu Hong , Deng Zong Quan , Gao Hai Bo
Published: March 2009

In order to implement basic motion functions of lunar rover over uneven terrain, wheel
kinematics of a novel lunar rover with each wheel independently driven was studied. In terms of
mechanism principle and configuration features of the rover the kinematics model of wheels was set
up by utilizing modified D-H method. The simulation analyses of wheels traversing over uneven
terrain were carried out by using MATLAB software. The velocity simulation curves of wheels’
centers relative to rover body were acquired. The research results give motion parameters of wheels
varying with rough terrain, and from the velocity simulation curves we can gain velocity control
instructions of rover wheels over uneven terrain. It illustrates varying of lunar rover wheels’ velocity
with uneven terrain. The paper provides a theoretical basis for accomplishing motion control and
autonomously avoiding obstacles of lunar rover and so on.
NURBS Interpolator Based on Dynamic Property of the Machine Tool
Authors: Shen H.Y. , Fu Jian Zhong , Chen Zi Chen
Published: March 2009

The proposed Axis-based Look-ahead NURBS Interpolator (ALANI) strictly confines the component acceleration and jerk at each axis during every interpolating period based on the mechanics of the machine tools, so that the acceleration and jerk at axes can not exceed the limit in order to avoid immoderate vibrations and shocks. Contour precision is also strictly guaranteed while interpolating. The interpolator can trace back and recalculate previous data if necessary after forwards calculation and verification. And the recalculation algorithm is able to choose optimized machining parameters to attain high efficiency. The introduction of ALANI and simulation experiment is present in this paper.
Study on Interpolating Algorithm of Hybrid Machine Tool
Authors: Shi Hong , Xu W. , Huang F.X.
Published: March 2009

Hybrid machine tool is studied in this paper and its interpolating algorithm strategy is
analyzed including line and arc rough and fine interpolation method. Cubic B spline is used as fine
interpolating algorithm and error evaluation of arc interpolating algorithm is presented. This
algorithm model is sample and can be used in many situations.
A New Position-Finding Method for Machining Huge Workpiece
Authors: Wu Jia Feng , Gao Dong , Yao Ying Xue
Published: March 2009

A position-finding method for machining huge workpiece is presented in this paper, and the principle of intelligent position-finding machining system is proposed. Based on automatic determining the position and orientation of the fixed workpiece frame relative to the movable machine-tool frame, the position-finding model is erected and solved by modified Euler angle and Hong-Tan algorithm. The theoretical analysis and simulation examples demonstrate the validity of the proposed method, and the results indicate that the method is suitable for machining huge workpiece in significant scientific projects.
Research into the New Process and Machine for Auto-Bending of Mine-Used Tri-Ring Chains
Authors: Xiao Y.H. , Liu Bin , Liu Qing Hui
Published: March 2009

Mine-used tri-ring chains have been bent by hand in some machine-mining enterprises.
However, this type of process is old-fashioned. The labor intensity of operating workers is high and
production efficiency is low. At the same time, the production quality is also unstable. This type of
process has not adapted itself to the manufacture of the product. So, for the mine-used tri-ring chains,
a novel and simple auto-bending ring machine has been designed. The machine has the advantage of a
simple frame, convenient mould-removal, production efficiency, steady production quality, and so
on. The machine can be used for medium and small manufacturing. The machine can also be adapted
for auto-bending of tri-ring chains if it is equipped with a delivery device, heating device and the
appropriate controlling circuit.
Study on Forming Quality Control of Bending Tube in Power Station Boiler
Authors: Lai Yi Nan , Ren Sheng Le , Zhang G. Y. , Liu Gang Feng
Published: March 2009

A FEM-numerical simulation system is developed to simulate the process of rotary draw
bending of tube. The emphasis is to discuss some factors such as tube materials, bending moment of
fan-shaped die, pushing force of sliding slot and tube relative bending radius which have an effect on
tube bending quality. The quality parameters of ovality, thinning ratio and thickening ratio are the
same as the measurement values in the practical production. Some improved methods are put forward
to according to the simulation results. The experiment shows that the simulation system can forecast
accurately the deformation in the process of tube bending, so the production manufacturing cost
decreases greatly.
Research on Key Technology of Hydrostatic Motorized Spindle and its Designing
Authors: Lu Ze Sheng , Ma Bing Hui
Published: March 2009

Motorized spindle is high speed machining unit combined with hidden motor and
machine tools axis, which has advantages of high speed, stepless transmission, zero transmission
chain, and is applied in machine center widely. Key technologies are combined together in
motorized spindle designing, such as high speed motor, bearing, manufacturing and assemblage. It
is strict in assembling to guarantee rotating precision and dynamic balance and is different from
common machine tools designing due to characters of high speed and hidden motor. Hydrostatic
bearings have advantages of high carrying capacity, lower friction, and better holding precision, the
heat problem is extrusive, but the future of hydrostatic motorized spindle is considerable. Modal
and thermal performance analyses are necessary for motorized spindle designing. With modal
analysis, inherent frequencies are confirmed, which could be of help to avoid sympathetic vibration
in machining. It provides evidence for designing cooling system of thermal performance analysis.
Numerical Simulation and Experimental Measurement of Velocity Field of Powder Fluid in Laser Manufacturing
Authors: Yang Xi Chen , Yang N. , Dong Z.
Published: March 2009

Laser direct manufacturing and re-fabricating have been used in many important fields in recent years. However, simulation and measurement of velocity fields in carrying gas and powder particles are still a challenge. In this paper finite difference method has been selected to simulate the velocity fields of powder/gas fluid. A novel DPIV system has been developed to measure the velocity fields. The DPIV system mainly consists of Nd+:YAG laser and CCD camera. Comparing the result of DPIV measuring with computer simulating, a good agreement can be obtained. After further developing, DPIV will become a useful device for laser manufacturing.
Research on New Architecture for Open CNC System Based on Linux
Authors: Huang Q.X. , Lin Shu Wen
Published: March 2009

In accordance with slow running speed in present soft CNC system, which is difficult to be
adapted to machining with mass of data at high speed, an open architecture of soft CNC system with
high performance is presented, which is based on PC+I/O hardware interface and satisfies the
requirement of real time performance in data transmission by use of the fifos of RTAI, of which
modules are redundantly designed to make its functions reconstructable, extensible and open by use
of the routing technology of soft switch. In this system, functions of fine interpolation and movement
control, a small portion of CNC system’s functions, are performed by the designed simple I/O
hardware interface. It is expected to greatly improve the real-time performance and satisfy the
requirement of high running speed in CNC system.
Realization on Fractal Interpolation of Non-Rule Geometry
Authors: Sun B.W. , Jiang L.T. , Pan H. , Zhu H.
Published: March 2009

The traditional geometric modeling is generally described by means of Euclidean geometry, and objects for the geometric modeling are usually artificial work-pieces with smooth and regular contour. However in real world, there are so many irregular geometric objects(such as cavernous body, geological body, rough surface body and so on) with extremely complicated structure that the constructing method based on Euclidean geometry equation has been already helpless, while the process constructing method based on fractal geometry can. Taking rough surface body as examples, in order to explore a method for non-rule geometric modeling based on step-by-step subdivision. Research shows that such methods can preferably represent structure characteristics of non-rule geometric modeling, consequently opening up a new way for expanding the scope of geometric modeling and enhancing the capability of CAD.
High Speed Milling Stability of Cutter with Indexable Inserts
Authors: Zheng Min Li , Jiang Bin , Zhang W. , Liu J.
Published: March 2009

Based on dynamic loads analysis for high speed milling, to investigate vibration and
failure of high speed milling cutter with indexable inserts, and perform modeling for high speed
milling stability based on safety. According to the theory of axiomatic design, to process
decomposition of function of high speed milling cutter with indexable inserts, found the design
matrix of cutter, and propose the design method of cutter based on high speed milling stability, high
speed face milling cutter for machining aluminum alloy was developed. The results indicate that an
uneven distribution of cutter teeth and higher precision of dynamic balance can depress vibration of
cutter, the method of axiomatic design based on stability improves efficiently dynamic cutting
stability, the safety and concurrent design cycle of high speed milling cutter.
Research for Disposable Design Concept and its Method
Authors: Li F.X. , Wang Guang Lin , Wang Hui Feng , Deng Zong Quan , Sun Y.H. , Xue H.Y.
Published: March 2009

This paper puts forward the concept of “disposable machine”, analyzes the characters of the disposable machine and introduces the design method of disposable machine taking spur gear for example. The validity of the design has been proved through emulation experiment. Compared with traditional and normal design, disposable machinery has advantages of lower price because of less capacity and weight.
Product Rapid Design for Customer Individual Requirements
Authors: Ge Jiang Hua , Wang Ya Ping , Gao Guo An , Huang Yong Tao , Xu Y.L.
Published: March 2009

Based on product configuration and modular design, a product rapid design method for customer individual requirements was proposed. Aiming at the product configuration correlation of this product rapid design method, we classify the product in accordance with the product functional modular classification principle, define the correlation between the functional modules, set up the correlation matrix between each module and recognize the customer demand of individual product configuration immediately by using the exclusion algorithm. At last, taking multimedia LCD projector as paradigm, we verify this method.
Parametric Design on 3D Complex Groove of Turning Inserts Using Pro/Engineer
Authors: Feng X.M. , Tan Guang Yu
Published: March 2009

One main method of chip breaking is to use the grooves which can make chips be broken.
3D complex grooves meet the requirements of controllable chip breaking. It is too complicated to
design 3D complex grooves using AutoCAD in short periods because each section of them is
intricacy. Thus the author established the parametric model of the groove based on the advanced
functions of Pro/Engineer, in which parameters can be obtained, transferred and modified through
setting up parameter relations and compiling control programs. The combination of representative
elements constituting the solid model of 3D complex grooves can be achieved by just inputting
parameters, which can be directly transformed into 2D drawing accordingly; the heavy work of
drawing complex surfaces using AutoCAD can be avoided; and the curvature of each normal profile
of grooves are gotten. All such work lays a foundation for the groove design and optimization.
A Fast Algorithm to Compute B-Splines and its Application in Curve Fitting
Authors: Sun Hai Yang , Chai M. , Fan Da Peng
Published: March 2009

B-spline method plays an important role in data interpolating, fitting and smoothing.
Through analyzing the computed path of the de Boor-Cox algorithm, a new method for calculating
B-spline function is given based on the vector extending operation. The proposed method has a
parallel computing architecture and is suitable to realize by computers. Compared with the de
Boor-Cox algorithm, the proposed method can improve computing efficiency by (2k+1) times in the
task of calculating all nonzero values of k-degree B-spine functions. As an application in B-spline
curve fitting, it shows that the proposed algorithm can reduce the computing efforts obviously.
Modeling and Simulation of a Micro-Actuator with Long-Travel
Authors: Jiang W.R. , Lu Ze Sheng
Published: March 2009

A microactuator with long-travel and high-resolution based on the principle of tribology
is presented, which stroke is up to 300mm and displacement resolution is 0.01μm. It resolves the
contradiction of large-stroke and high-resolution in macro/micro drive successfully. The dynamic
model of the microactuator is set up. The theory analysis on the dynamic character of the system is
carried out based on Karnopp “stick-slip” friction model. The physical and mathematical model of
the drive part and transmission part are set up respectively by the method of modularization. The
transfer function of the system is attained. The tacking simulation is carried out based on fuzzy
control with speed change integral, the result is proved that error is 0.004μm.
Workflow Modeling for Cooperative Production Development Based upon Advanced Petri Net
Authors: Zou L.H. , Gou D.M. , Sun C.L. , Gao H.
Published: March 2009

Process modeling of Cooperative Product Development (CPD) is the key of CPD process
management. Analyzing the process of developing production based upon Petri Nets, referring to
workflow management and combining with parallel project, a new workflow modeling method
based upon layered timed color Petri nets is invented, which supports the developing of the model
production that parallels CAD/CAPP. Finally taking the developing CDP of model product as an
example, workflow model has been designed and has been inspected and verified in the software
platform.
Distortion Prediction of Aerospace Monolithic Components due to Milling Process
Authors: Bi Y.B. , Dong Hui Yue , Cheng Qun Lin , Ke Ying Lin
Published: March 2009

A physics-based material processing simulation is approached to reveal the distortion law
of aerospace monolithic components due to milling. To improve the efficiency of numerical
calculation, a simplified cutting layer model is presented. The cutting force and temperature model
are established to gain cutting loads. The cutting loads are applied to the mesh model of the part.
The milling process of spar is simulated. Key factors influencing distortion such as initial residual
stress, cutting loads, cutting sequence and tool path are considered. The total distortions of the spar
are estimated. Machining experiment is carried out, and the distortion tendency of the machined
part agrees well with the simulation. The results show the validity of the presented approach.
Network Architecture Based on 3-D Digital Design and Manufacture for Scaled Enterprise Ally
Authors: Gu Li Zhi , Gao Y. , Zhang Q.
Published: March 2009

With the features of rapid response, premium quality, low cost, flexibility, technology of digital design and manufacturing is becoming the principal boost that enhances the manufacturing industry in the 21st century. There are about several hundreds of thousands of scaled manufacturing enterprises that face the upgrading challenge of production technology, organization, and management transformation with the core alteration from 2D design- conventional manufacturing to 3D digital design and digital manufacturing. Netting of three-D digital design and manufacturing system is the only way of upgrading the manufacturing industry orientating to future. An idea of scaled enterprise ally is presented, and based on the scaled enterprise ally, netting frame is put forward and constructed of the digital design and manufacturing system, expounding the functions and features of shared data platform, those of linkages of digital design, digital manufacturing, cell enterprise management, and CSG modeling technique, creation procedure of CAPP, virtual testing technique in the digital design and manufacturing systems, explaining the key considerations including interrelationships among the enterprises , resources share, information security, network security.
Research on the Net Transparent Bridge Technology Based Single NC Machine’s Network Integration
Authors: Zhang J.G. , Li H.J. , Wu X.G. , Peng W.
Published: March 2009

In the face of the development trends of NC machine’s networking, this paper presents a
new method of transferring NC program based on net transparent bridge technology. By analyzing
the principle of serial port communication between NC machine tool and computer, this paper
demonstrates the fundamental of net transparent bridge, topology structure, software and hardware
realizing of communication function. The single NC machine networking in field showed that the
preset qualifications can be reached, which makes the network integrations of existing single NC
machines possible.
CPLD Application in the Development of the Pin Selection Controller in Knitting Machine
Authors: Zhang J.G. , Wu X.G. , Zhang C. , Zhang C.J.
Published: March 2009

By the help of professional CPLD software/hardware development tools like PLD carrier
and MAXPLUS, this paper successfully put forward the objective device—Electrical Pin Selection
Controller in Circular Weft Knitting Machine, which covers the primary aspects of expected inputs,
electrical simulation and verification, programming and downloading, etc. Details have been given
on how to apply CPLD in the pin selection controller design. Moreover, introductions have been
given to the pin selection mechanism and the design schema.
Real-Time Monitoring System of Cutting Process Based on Cutting Temperature
Authors: Quan Yan Ming , Zhao Jing , Le Y.S.
Published: March 2009

Cutting temperature measurement and its variety tendency can reflect cutting tool
performance and machined surface quality directly. By means of a mercury current collector or an
electrical brush device the online measurement of thermoelectric potential of tool-workpiece natural
thermocouple in milling is obtained, based on which a new cutting process real-time monitoring
system is developed. The system takes the average cutting temperature in tool-workpiece interface as
the monitoring target and the rotation rate of machine spindle as the adjustment object, which leaves
out onerous and complex modeling and makes the monitoring and adjustment objective, direct and
effective.
Study on the Orthogonal Cutting Process of Al7050T7451 with Uncoated and Coated Tools
Authors: Dong Hui Yue , Huang Pu Jin , Bi Y.B.
Published: March 2009

Tool wear during high speed machining process plays an important role in machining
cost and efficiency. The purpose of this study is to examine the impact of tribological properties of
coatings on cutting performance. Finite element methods (FEM) were used to model the effect of
coated and uncoated cutting tools (K10) on the machinability of the aluminum alloy 7050T7451.
Uncoated, Single coated, such as TiC, TiN and Al2O3 and multi-coated tool were studied. All finite
element models were assumed to be plane strain. To achieve constitutive model of Al7050T7451
under conditions of machining that high strain rate, high strain and high temperature occur, high
speed impact experiment and material drawing experiment were done. Comparison of FEM results
shows that the highest temperatures in tools, the temperature change rates of different tools from
surface to its bulk material, and the temperatures in chips are changed greatly. It also shows that the
cutting temperature of coated tool is lower than uncoated tools, but cutting forces change very little.
All these results show that coatings can be used to reduce adhesion between a tool and a workpiece
material. The wear resistance of coated tool can be improved effectively and tool life is increased
correspondingly.
Optimization Design of Planar Five-Bar Parallel Robot's Bar Length
Authors: Wang Na Jun , Liang Chun , Shi P.
Published: March 2009

The target movement range of planar five-bar parallel robot is decided by the length of
each bar and swinging angle. In general designs are bound by the single-objective optimization.
Scope of the overall movement is considered as the goal of optimization. Although this method may
seek all the possible movement scope completely, but has actually neglected the restraint of
mechanical hinge structure. To determine the length in this way there are interference and stuck
phenomenon. To address this issue in this paper the bounds of mechanical structure are added in. A
new set of optimization algorithms is established. Analytical method is used to establish the
algorithm of planar five-bar parallel robot’s positive solution. Then MATLAB is used to obtain the
positive solutions of target movement range. Generally under unconstrained circumstances, we found
that there are two positive solutions and mutual symmetry on the x-axis. After adding in the
restriction of swinging angle, we succeed in finding the optimal solutions. Finally we use an example
to explain how it works. MATLAB is used to determine the length of each bar and found a 200 x 150
mm of the target movement range. Through the diagram has been plotted by MATLAB, we find that
the second solution is the optimal solution. This method can be used to optimize the length of planar
five-bar parallel robot.
Study of the Bioactive Behavior of Thermally Treated Modified 58S Bioactive Glass
Authors: Goudouri Ourania Menti , Chatzistavrou Xanthippi , Kontonasaki Eleana , Kantiranis Nikolaos , Papadopoulou Lambrini , Chrissafis K. , Paraskevopoulos Konstantinos M.
Published: March 2009

Thermal treatment of bioactive glasses can affect their microstructure and thus their bioactivity. The aim of this study was the characterization of the thermally treated sol-gel-derived bioactive glass 58S at characteristic temperatures and the dependence of its bioactive behavior on the specific thermal treatment. The thermal behavior of the bioactive glass was studied by thermal analysis (TG/DTA). Fourier Transform Infrared Spectroscopy (FTIR) and X-ray Diffractometry (XRD) were used for the characterization of the bioactive glass. The bioactive behavior in Simulated Body Fluid (SBF) was examined by Scanning Electron Microscopy (SEM-EDS) and FTIR. The major crystal phases after thermal treatment were Calcium Silicates, Wollastonite and Pseudowollastonite, while all thermally treated samples developed apatite after 48 hours in SBF. A slight enhancement of bioactivity was observed for the samples heated at the temperature range 910-970oC.
Investigations on Explanted Ceramic-Ceramic Couplings after Squeaking
Authors: Oberbach Thomas , Kempf Katrin , Ortmann Claudia
Published: March 2009

In the present investigation, three ceramic-ceramic-couplings (alumina - alumina) were examined for possible reasons of the squeaking noise which occurred after surgery. Under certain conditions like, for example, a suboptimal position of the implant and corresponding soft tissue relations, a subluxation or microseparation of the ceramic head from the ceramic liner may occur; this, in turn, may lead to a squeaking noise of the joint. Apart from the psychological stress for the patient due to the awkward noise and the resulting feeling of instability, the squeaking noise is a sign for damages on the implant in most cases.
Concept of a Bioactive Implant with Functional Gradient Structure
Authors: Sousa T. H. S. , Fortulan C.A. , Antunes E.S. , de M. Purquerio B.
Published: March 2009

A material able to be used as bone implant for specific applications was developed. The proposed solution establishes that all implant surfaces should be bioactive since porous surfaces in contact with bone are extremely necessary for bone adhesion. The bioactive material composite with high mechanical strength designed with a PMMA functional structure gradient produced in this work has a dense core enveloped by a porous bioactive surface. Pore sizes and shapes as well their interconnectivity was analyzed by SEM tests; the cytotoxicity was investigated in vitro using Vero cell and bone conductivity and biocompatibility was investigated in vivo in rabbits. The implant porous bioactive part analyzed in vitro showed no toxicity and tests in vivo showed a remarkable biocompatibility and bone cell growth. Some samples with hydroxyapatite (HAp) were analyzed by EDX and SEM tests, the results showed a fair hydroxyapatite distribution in the implant pore surfaces as much as a part which was retained inside the PMMA inner porous. The average scaffold pore sizes obtained was around 250.0µm and the diameter shrinkage of 4.0% was observed in all samples. This study demonstrated that the functional gradient structure composite studied can be a good candidate for cranial bone implants due to its good bone conductivity and biocompatibility.
Periostal Reconstruction Using New Porcine Microstructured Collagen Membrane and Calcium Phosphate Cement: A Dog Model
Authors: Jegoux Franck , Goyenvalle Eric , Aguado Eric , Cognet Ronan , Moreau Françoise , Daculsi G.
Published: March 2009

The aim of this study was to evaluate the capacity of the association of calcium phosphate cement with collagen membrane for large segmental bone defect. Six adult beagle dog underwent defect creation in the ulna and was reconstructed with combination of macroporous calcium phosphate cement MCPC® and resorbable collagen membrane EZ Cure®. After 6 months of implantation, the samples were analyzed with Micro CT, light microscopy and SEM using BSE. Bridging of the defect with a lamellar and well organized bone was achieved in all animals. MCPC granules resorption was increased at the extremities of the implant. Collagen membrane at the expense of the implant was replaced by periosteum-like formation. The results demonstrate the ability of the composite to reconstruct large segmental and critical size defect in long bone.
Techniques to Study Cellular Response in Critical Size Bone Defect Healing on Rat Calvaria Treated with Hydroxyapatite Implants
Authors: de Freitas Costa Neusa Motta , Raposo Melo Bruno , Tavares Brito Rosana , Fernandes G.V.O. , Bernardo Vagner Gonçalves , Carvalho da Fonseca Eliene , Conz Márcio Baltazar , de Almeida Soares Gloria Dulce , Granjeiro José Mauro
Published: March 2009

The aim of this paper was to evaluate the usefulness of coupling digital image analysis with immunohistochemistry and histomorphometry data to the study of tissue response to hydroxyapatite in a model of critical size bone defect in calvaria of rats. A transosseous defect measuring 8 mm in diameter was performed with a surgical trephine in the parietal bone of 40 rats and divided into two experimental groups according to the treatment: group I (blood clot, control), group II (HA) and killed 1, 3, 6 and 9 months after implantation (n=5/group/period). The skullcaps with overlaying skin were collected and processed for paraffin embedding. The specimens were cut in the laterolateral direction into 5-µm thick semi-serial sections and stained with hematoxylin-eosin for identification and counting of polymorphonuclears cells, mastocytes, and multinucleated giant cells, MNG, or immunolabeled with anti- lysozyme, -factor VIII and –PCNA. Digital images were obtained and analyzed with the ImagePro-Plus® software for cell couting (polymorphonuclears cells, mastocytes, macrophages and MNG) and microvessel density. Image segmentation of anti-PCNA immunostaining was used for cell proliferation analysis. The digital images obtained allowed clear identification of cells of interest by through morphological aspects or immunostaining. Data recording and analysis was facilitated by the use of specific software for image processing and graphical and statistical analysis. It can be concluded that the techniques applied were usefull to identify and count cells, structures and process of interest making easier the effectiveness of hydroxyapatite in the critical size defect in rat calvaria model.
Use of Complexing Agents in Hydroxyapatite Synthesis
Authors: Arce Heilen , Montero Mavis L.
Published: March 2009

Production of calcium phosphates from homogeneous solutions of Ca2+ and PO43- are studied in presence of complexing agents such as acetic acid, lactic acid, etilendiaminotetracetic acid (EDTA), iminodietanoic acid, and malic acid; solids are characterized with infrared spectroscopy (IR), powder x-ray diffraction, scanning electron microscopy (SEM) and electron dispersion spectra (EDS). The objective for this experiment was to find a suitable complexing agent to produce hydroxyapatite under mild reaction conditions. With the methodology described only tree phases are produced: brushite, monetite and hydroxyapatite. It is found a relationship among the ligand and the calcium phosphate phase obtained, where the complexing agent that provides the best working conditions for hydroxyapatite production is EDTA.
The Effect of Bioceramic Surface Modifications on Different Endosseous Implant and Surgical Design. A Series of In Vivo Studies in Dogs.
Authors: Coelho Paulo Guilherme , Suzuki Marcelo
Published: March 2009

The objective of this series of experiments was to evaluate the effect of bioceramic
coatings/ incorporations on implant surfaces as a function of implant and surgical drilling design.
Methods: A series of four in vivo studies were conducted utilizing the dog proximal tibia model.
The models provided implants that remained from 2 to 5 weeks implantation time. The different
studies comprised the placement of implants with intimate contact with bone following placement
and implant designs that resulted in healing chambers. The various implant types presented surfaces
with and without Ca- and P-based bioceramic incorporations. Biomechanical and
histomorphometric measurements along with qualitative bone-implant interface morphology
evaluation were performed. For all studies, one-way ANOVA at 95% level of significance was
employed along with Tukey's post-hoc multiple comparisons. Results: Close contact between
cortical and trabecular bone and all the different implant surfaces irrespective of implant fit (with
and without healing chambers) showed that all surfaces were biocompatible and osteoconductive. In
general, appositional bone healing was observed at all implant regions that were in intimate contact
with bone immediately after placement, and an intramembranous-like healing occurred throughout
the whole volume of the healing chambers. Irrespective of implant + surgical drilling design, the
presence of Ca and P resulted in a bone morphology that showed primary osteonic structures at
earlier times than uncoated surfaces. Conclusion: Irrespective of implant design and surgical
drilling combination, the presence of Ca and P on the implant surface positively modulated early
healing around endosseous implants.
Bovine Hydroxyapatite (BHA) Strontium Oxide Composites
Authors: Gunduz Oguzhan , Ozyegin L.S. , Dorozhkin Sergey V. , Meydanoglu Onur , Eruslu Niyazi , Kayali S. , Goller Gultekin , Agathopoulos Simeon , Oktar Faik N.
Published: March 2009

Composites of calcinated bovine bone derived hydroxyapatite (HA) with 5 and 10 wt % SrCO3 were prepared by sintering. The production of HA from natural sources is preferred due to money and time saving reasons. In this study scanning electron microscopy (SEM) investigations and together with measurements of microhardness, density, and compression strength were performed. The experimental results indicated that compression strength and microhardness values of HA-Sr-oxide composites decrease when the content of SrCO3 and sintering temperature increase. The best compression strength values were achieved after sintering at 1000°C. It was seen that at higher temperatures the compression strength and the microhardness values decrease due to the pore formation. The pore formation is very important for scaffold formation for tissue engineering purposes.
Fabrication of Bioactive Organic Polymer by Using Apatite Nuclei-Contained Inorganic Binder
Authors: Yabutsuka Takeshi , Inoue Yuzo , Shimada Masayuki , Hibino Mitsuhiro , Yao Takeshi
Published: March 2009

Apatite nuclei were dispersed in inorganic binder and the apatite nuclei-contained inorganic binder was coated on polyethyleneterephthalate plate. Hydroxyapatite was induced by the apatite nuclei dispersed in the binder and hydroxyapatite layer was formed on the surface of the substrate by soaking in SBF. The hydroxyapatite layer showed high adhesive strength to the substrate.
Rapidly Resorbable, Temporarily Mechanically Stable Composites for Bone Replacement
Authors: Bielefeldt Nicole , Ploska Ute , Berger Georg , Heimann Lydia
Published: March 2009

This study describes the preparation of a composite material [1] from synthetic nano-scaled hydroxyapatite (nHA) and a gelatin matrix (80% nHA, 20% gelatin). This composite material is intended to extend the range of biological hydroxyapatite-based defect-filling materials for bone replacement. Ostim® (aqueous suspension of nHA having a crystallite size of about 20nm) was used as the inorganic component whereas porcine gelatin (type A, 180 Bloom) composed the organic part. Both components were homogenized during a spray-drying process. Cylindrical samples of the spray-dried granulate (HG 80/20) produced by pressing had adequate mechanical stability for storage, transport and handling in the surgery. The flexural strengths for the samples were determined on dry samples as well as after storing in media (distilled water, SBF solution) for 60 minutes. After staying 30 minutes in a SBF solution or in water, flexural strength dropped off about 30% while the shape of the sample was retained. Temperature treatments of both granulate and pressed samples resulted in reduction of the sample swelling from 70vol-% to 50vol-%. The sample produced by pressing can be machined (turned, drilled, milled).
Adsorption of Proteins Derived from Fetal Bovine Serum onto Hydroxyapatite Nanocrystals with Quartz Crystal Microbalance Technique
Authors: Tagaya Motohiro , Ikoma Toshiyuki , Takemura Taro , Okuda Mitsuhiro , Hanagata Nobutaka , Yoshioka Tomohiko , Chakarov Dinko , Kasemo B. , Tanaka M.
Published: March 2009

The adsorption of multiple proteins derived from fetal bovine serum (FBS) in phosphate buffer saline (PBS) and alpha minimum essential (aMEM) was in situ analyzed with a quartz crystal microbalance with dissipation technique on gold, titanium and HAp sensors. The adsorption behaviors of FBS proteins were varied depending on the sensors. The DD/Df value of the HAp sensor were clearly different in PBS and aMEM, and others were not changed. The viscoelastic properties of the protein films adsorbed on the HAp sensor in PBS were flexible in comparison with those on the gold and titanium sensors. The D-f plots incidated that the proteins adsorbed on HAp in PBS would lead to competitive adsorption and conformational change and those in aMEM could form a monolayer. The adsorption behavior on the HAp in carbonate buffer saline was found to be similar to that in aMEM. These differential adsorption behaviors on the HAp surface were attributed to the pre-adsorptive ion, such PO43- or CO32- in the solvent.
Elaboration of a Well-Ordered Porous Bioceramic via a Heterocoagulation Colloidal Process
Authors: Chotard-Ghodsnia Roxana , Lucas Sandrine , Pagnoux Cecile , Champion Eric , Viana Marylène , Chulia Dominique , Anselme Karine , Chartier Thierry
Published: March 2009

The purpose of this study was to develop bioceramics with a well-defined porous structure in order to control drug loading and release over time. Porous structures were obtained through colloidal processing, using polymethyl methacrylate (PMMA) microspheres as templates (core) and hydroxyapatite (HA) nanoparticles as inorganic building blocks (shell). Dispersed HA suspensions were prepared and their electrokinetic properties were studied to determine a dispersant giving a high positive zeta potential (opposite to the negative zeta potential of PMMA). Upon mixture of well-dispersed HA and PMMA suspensions of opposite charge, core-shell structures were formed via heterocoagulation. After consolidation, polymers were removed by calcination, resulting in a porous structure of controlled size and distribution.
Comparison of Hydroxyapatite and AB-Type Carbonate-Substituted Hydroxyapatite Suspensions for Use in the Reticulated Foam Method of Scaffold Production
Authors: Robinson J.H. , Best Serena
Published: March 2009

Precipitation routes for HA production result in the formation of suspensions of nano-scale hydroxyapatite particles in water. During this work, suspensions of phase-pure and carbonate-substituted hydroxyapatite were produced using a precipitation reaction with calcium hydroxide and orthophosphoric acid as reactants. The chemistry of the apatites was analysed using XRD and FTIR after heat treatment in various atmospheres and the particle morphology investigated using TEM. The thermal stability of the carbonate HA was found to be significantly less than the phase-pure HA and dependent upon the heat-treatment atmosphere. Suspensions were used directly for replication of polymer foam templates with a dip-coating technique. Good replication of the foam structure was achieved with the phase pure hydroxyapatite, but no structural integrity was achieved with the carbonate-HA structure possibly a result of limits on the sintering temperature.
Development of Calcium Phosphate Mineralized Silk for Potential Use in Guided Bone Regeneration: Preparation and Properties
Authors: Chou A.H.K. , LeGeros Racquel Z.
Published: March 2009

Silk has been used in biomedical applications for centuries. The potential of silk for application in tissue engineering is currently being explored. The purpose of this study was to develop new method of mineralizing silk with carbonate apatite and determine cell response. The cocoons were placed in sodium bicarbonate solution and heat treated. The treated silk fibers were mineralized with carbonate apatite (CHA) using precipitation and new microwave methods. The mineralized and non-mineralized silks were characterized using SEM, EDS, XRD, FT-IR, and TGA. Cell response to mineralized silk and non-mineralized silk was determined using human osteoblast like cells (MG-63). The microwave method was more efficient than the precipitation method in terms of the amount of minerals incorporated with the silk and time required for mineralization. EDS, FT-IR and XRD identified CHA in the mineralized silk. In terms of cell response, greater production of type 1 collagen was observed with CHA mineralized silk compared with non-mineralized silk.
Resorption Mechanism of Hydroxyapatite and β-Tricalcium Phosphate Coating Layer
Authors: Lee Kang Sik , Chang Jae Suk , Kim Jung Hwa , You Chang Kuk , Kwon Hoon , Lee Dong Ho
Published: March 2009

Beta-tricalcium phosphate(β-TCP) coating layer is known to be resorbed much faster than hydroxyapatite(HA), however, there has been no report to explain the exact reason of these results. Eighty titanium discs, coated with HA(n=40) or β-TCP(n=40) by dip and spin coating method, were divided into 2 subgroups respectively; Dissolution(D, n=20) and osteoclast culture(C, n=20). The coated discs in D group were immersed in the cell culture media for 5 days, whereas, in C group, osteoclasts were seeded on the specimens and cultured for 5 days. After simple dissolution test, β-TCP coating layer showed much more cracks and denudation as compared to HA. In osteoclast culture group, mean area fraction of resorption pits in HA-C group was 11.62%, which was significantly higher than that of 0.73% in β-TCP-C group(p=0.001). In conclusion, the resorption mechanisms of HA and β-TCP coating layers were different each other in vitro study. The coated β-TCP was degraded mainly by dissolution and separation from implant, on the other hand, the HA coating layer was resorbed by osteoclastic activity.
Mechanical Properties of Alite-Calcium Barium Sulphoaluminate Cement Concrete
Authors: Zhou Zong Hui , Lu Ling Chao , Gao Xing Kai , Cheng Xin
Published: March 2009

In this paper, preparation and mechanical properties of Alite-calcium barium sulphoaluminate (Alite-C2.75B1.25A3 ) cement concrete were studied. The results showed the compressive strength of Alite-C2.75B1.25A3 cement concrete was much higher than that of Portland cement concrete, especially the early-age compressive strength. The 24-hour compressive strength of Alite-C2.75B1.25A3 cement concrete could reach 22.81Mpa for w/c=0.45, 17.29Mpa for w/c=0.50 and 17.04Mpa for w/c=0.55 respectively. They were about 50 to 65 percent higher than those of Portland cement concrete. The 7-day compressive strength could reach about 80 to 90 percent of 28-day strength for Alite-C2.75B1.25A3 cement concrete. The 28-day strength could reach 55.85Mpa for w/c=0.45, 48.01Mpa for w/c=0.50 and 44.21Mpa for w/c=0.55 respectively. The results of SEM showed the interfaces between the hardened cement paste and aggregates in Alite-C2.75B1.25A3 cement concrete were more compact than those in Portland cement concrete. Distribution of particulate bulk was more uniformity and a majority of clinker particles was wrapped by hydrated gel in Alite-C2.75B1.25A3 concrete. And, the structure of Alite-C2.75B1.25A3 cement concrete was much more compact than that of Portland cement concrete.