bluuebunny/crossref_metadata_2025 huggingface dataset:
Studies on Ceramic Cutting Tool Wear for the High Speed Milling Nickel-Based Superalloy
Authors: Zhao Can , Shi Yang Yang , Qi Min , Wang Zi Biao , Xi Wang
Published: July 2014

According to the principle of ultrasonic vibration turning, the first step is to study different position changes of surface roughness with cutting parameters under ultrasonic vibration turning of slender shaft by the test of single factor, and determining the extreme position of surface roughness with the slender shaft changes in different cutting conditions. The second step is to study the influence of cutting parameters on the overall average surface roughness of work piece under ultrasonic vibration turning of slender shaft by orthogonal test design, and compared with the conventional turning. The experimental results show that ultrasonic vibration turning slender shaft processing can significantly improve the surface roughness. At the same time, the influence laws of cutting parameters on the surface roughness are investigated, and finding out the optimal cutting experimental parameters.
Milling Force Modeling and Experimental Research of 300M Ultra High Strength Steel
Authors: Zhang Hui Ping , Wang Chong Xun , Lai Yi Nan , Zheng Wen Juan
Published: July 2014

300M ultra high strength steel, a new type of steel with broad prospects for development, has good mechanical properties, and is widely used for manufacture of aircraft landing gear. In order to reveal influence law of cutting parameters on milling force of 300M ultra high strength steel, the influence law of feed rate, milling width, and depth of cut and spindle speed on milling force is firstly studied through the single factor experiments in this paper. Secondly, the influence level of experimental factors is compared by orthogonal experiment. Finally, combined with orthogonal test data and the least square method, the multiple linear regression model of milling force in 300M ultra high strength steel milling is built. The accuracy of the model has been verified well by experimental verification, which has the guiding significance to reveal the milling mechanism and actual production.
Numerical Modelling of Liquid Bearing Utilizing Traveling Waves by Using OpenFOAM
Authors: Li Ying Jie , Zhou Ming , Shamoto Eiji
Published: July 2014

A new type of hydrostatic liquid bearing utilizing traveling waves is proposed and analyzed in this research. In principle, the moving part of the proposed bearing is supported by a liquid film generated by the traveling wave transportation, which creates a liquid flow between the bearing and guide surfaces. A numerical simulation model for the unsteady and incompressible flow due to the traveling wave motion of the bearing surface is developed based on Navier-Stokes equations. The equations are solved discretely by dynamically meshing the isotropic 2D model and updating the boundary conditions. It reveals that the floating force varies with a nonzero average value. In order to suppress the undesirable fluctuation, voltage-offsetting technique has been proposed. Simulation results show that the steady floating force can be obtained. The proposed bearing design is ought to eliminate drawbacks of conventional hydrostatic bearings such as supply of external pressure source, use of compressor, and tubes while still achieving comparable static and dynamic capabilities.
Experimental Study of Tool Wear during Quasi High Speed Turning Titanium Alloy with Large Cutting Depth
Authors: Xu Li Fu , Dong Wei Liang , Huang Shu Tao , Dai Bao Lin
Published: July 2014

The wear morphology of rake face and flank face of tool is investigated by turning titanium alloy TC4 with CBN solid tool. It has been observed that the main wear form of rake face and flank face of tool is groove wear. The relation between tool flank wear and cutting speeds, feed rate, and cutting depth obtained from experimental data is given.
Effect Analysis and ANN Prediction of Surface Roughness in End Milling AISI H13 Steel
Authors: Zhang Qing , Zhang Song , Man Jia , Zhao Bin
Published: July 2014

Surface roughness has a significant effect on the performance of machined components. In the present study, a total of 49 end milling experiments on AISI H13 steel are conducted. Based on the experimental results, the signal-to-noise (S/N) ratio is employed to study the effects of cutting parameters (axial depth of cut, cutting speed, feed per tooth and radial depth of cut) on surface roughness. An ANN predicting model for surface roughness versus cutting parameters is developed based on the experimental results. The testing results show that the proposed model can be used as a satisfactory prediction for surface roughness.
Research on Surface Roughness in High Speed Face Milling Part 1: Theory of Prediction Model
Authors: Liu Lu Ning , Shi Zhen Yu , Liu Zhan Qiang , Song Kai Feng
Published: July 2014

The work-piece surface quality reflects the cutting performance of face-milling cutter. This paper presents the development of an algorithm to predict work-piece surface roughness in face milling operation. The prediction model is based on the face milling cutter fixed square inserts with flat edges. The static prediction model considers the effects of radial and axial run-out error of inserts, feed per tooth, tooth number, cutting edge length, nose radius, main lead angle, and axial depth of cut. The dynamic prediction model considers the effects of the Z-axial relative displacement between the work-piece and cutting teeth caused by forced vibration. By combining the prediction results of static and dynamic models, the surface roughness of the work-piece in face milling is predicted.
Research on Surface Roughness in High Speed Face Milling Part 2: Experimental Validation of Prediction Model
Authors: Liu Lu Ning , Shi Zhen Yu , Liu Zhan Qiang , Wang Yan Fang
Published: July 2014

The paper presents rigorous experimental validation results of the algorithm to predict work-piece surface roughness in face milling operation as developed in the Part 1. The experimental verification system consisting of various devices was established according to the given experimental conditions. Experimental parameters are set for steady face milling. Experimental data are collected through four experiments. These experimental data include the axial and radial run-out errors of each square insert with flat edge, the modal parameters of the face milling system, the Z-axial milling force and the measured surface contour of the milled work-piece. The trajectory of cutting teeth is calculated by the MATLAB software based on the static surface roughness model. Z-axial dynamic relative displacement between the tooth and the work-piece is obtained as the predicted dynamic surface roughness. By integrating the prediction results of static and dynamic models, the surface contour is predicted. Predicted and measured results are compared in the same figure and basically consistent. The work-piece surface roughness prediction model will be useful and valid in high-speed face milling.
Research on the Selection Problem of Machine Tools in Cloud Manufacturing Environment
Authors: Wang Shu Qi , Jiang Yun Xia , Zheng Min Li , Sun Dong Nan , Cheng Xiao Liang
Published: July 2014

This paper proposes a method to choose machine resources in order to realize the on-demand use of machine resources in cloud manufacturing environment. A convergence mode of the machine resources is described and the selection process is given. A multi-level matching process of machine tools is proposed. Different matching methods are designed for different parameter types of machining tasks and machine resources, and then machine resources are screened according to the requirements of machining tasks to form the machine resources candidate sets. Then a multi-objective optimal selection model of machine resources is constructed, regarding minimization of costs and time and maximization of service quality and reputation as the target, which is solved by using genetic algorithms. Finally, the algorithm is analyzed and validated with an example, and a kind of solution thinking and method is provided to select machine tools in manufacturing cloud environment.
Machining Error and Milling Process Control Methods for Joint Surface of Machine Tool
Authors: Jiang Bin , Zhang Kai , Yang Lin , Zhang Ming Hui , Wang Sheng Jie
Published: July 2014

The existing processes of controlling machining error just controlled the maximum error. However, it did not effectively control the distribution of the error.The reliability of the assembly precision of the key joint surface did not meet the requirements, thereby affecting the service performance of machine tool. To solve this problem, the error matrix and transformation matrix was used to ascertain the location of joint surface positioning error occurred. The influence of processing error on the the positioning accuracy of machine tool was analyzed. The control objective of milling process was proposed. At the same time, the effects of cutting parameters on the processing error were also studied according to the milling experiments. The process error and its distribution characteristics of joint surface were obtained by analyzing the relationship between deformation of joint surface and cutting parameters. The milling process control methods were proposed.
Optimization of Internal Pressure Loading Path for Tube Hydroforming of T-Shaped Tube Based on Dynaform
Authors: Wang Shi Gang , Chen Shun , Wang Dan , Xie Wen Cai
Published: July 2014

Take the T-shaped tube as the research object, studied the principles and theory. The paper researched the influence of single liner internal pressure loading path and bilinear internal pressure loading path and the gradient of internal pressure loading path on the forming quality of T-shaped tube with the help of FEA and DYNAFORAM simulation software. The paper researched the each method of forming process, and the relation between wall thickness thinning/thickening and the loading path of internal pressure, compared the similarities and differences. The results show that the gradient of internal pressure loading path is the best way, and the internal pressure should be increased growth rate in the pre-formed, so that get a small thickness reduction part.
Analysis on Vibration Modal and Noise Radiation of Cutter-Workpiece for Heavy Milling Processing
Authors: Gong Ya Nan , Cheng Yao Nan , Ao Xiao Chun , Liu Yi Zhi , Yan Fu Gang
Published: July 2014

For improving heavy milling machining environment, take the vibration modal and noise radiation distribution of milling cutter-workpiece as the research object, according to the characteristics of milling, consider vibration and noise generation in the milling process comprehensively, first establish the geometry model of cutter-workpiece, and then conduct finite element modal simulation and calculate the vibration response, so as to predict the distribution of noise field, and analyze the noise radiation, finally verify the vibration noise distribution of cutter-workpiece through milling noise distribution experiments, which lays the foundation for further research on vibration and noise reduction in heavy milling process.
Probe Mobile Device Design Based on a Weak Magnetic Detection Technology
Authors: Yu Feng Yun
Published: July 2014

Design and calculation of dual-use spiral mobile devices for horizontal and vertical, according to the principle of screw drive meet the needs of the weak magnetic detection technology. The device consists of the support part, guide part and transmission part, simple structure, may be supporting the use with weak magnetic equipment for the handheld single point measurement, and drive probe mobile to complete the measurement and maintained liftoff value unchanged in mobile. Carry on a large number of weak magnetic detection experiments using the device, the results proved that this probe mobile device easy to use, reliable mobile precision to meet the testing requirements.
Experimental Research on Temperature of Drilling CFRP with Brazed Diamond Core Drill
Authors: Mu Juan , Xu Jiu Hua , Chen Yan , Fu Yu Can
Published: July 2014

During the drilling process of CFRP laminate with brazed diamond core drill, drilling temperature is very important to the drilling CFRP with brazed diamond core drill, which will influence the tolerance, defects of CFRP. In drilling experiments of CFRP laminate, the temperatures under different cutting parameters were measured by an infrared camera, and the effects of drilling parameters on drilling temperature were analyzed and the influence of grits distribution on temperatures were also studied. The results shown the drilling temperatures rise while increasing density of grits, grinding speed, and decreasing feeding speed.
Research on Cutting Vibration in High-Speed Milling Nickel-Base Superalloy
Authors: Zhao Can , Wang Zi Biao , Wang Xue Hui , Xi Wang , Shi Yang Yang
Published: July 2014

Nickel-base superalloy GH4169 is a kind of alloy with high intensity, heat-stability and heat-fatigability, so that is often used to aerospace field, but which has poor machinability. The cutting force, plasticity deformation all present their particular characters which causes cutting vibration . The cutting vibration influence the surface roughness, the swing of the cutting force and tool wear. This article discusses the superalloy of GH4169 on the basis of cutting speed, cutting depth and feed per-tooth.
Review on Error Compensation Technology of Parallel Machine Tool
Authors: Zhou Liang , Tang Liu , Yuan Ju Long , Xie Da Gang
Published: July 2014

This paper reviews the development history of parallel machine tool and new achievements in China and abroad. Typical methods of error modeling, error detection and error compensation are introduced. After analyzing the biggest problem of recent error compensation technology, this paper prospects the further research trends.
Software Development of an Automatic Measuring Instrument for the Flatness Error of the Rail Wagon
Authors: Zhou Liang , Shang Wan Ru , Zhu Bo , Kong De Zhi
Published: July 2014

Matlab and Microsoft Visual C++ were used to program the automatic measuring instrument for the flatness error of the Rail wagon. Microsoft Visual C++ is used to program the struct body, which takes full advantage of the high programming efficiency, high execution speed and beautiful imple interface. In the meantime, powerful computational function and image fitting of Matlab is added to the program. Through the method of Dynamic Link Library, these two softwares are linked and the figure created by Matlab can be insetted in the main interface created by Microsoft Visual C++, which keeps the united and elegant appearance.
Study on Burr Removal Technology of Micro-Channelsby a Micro Slurry Jet
Authors: Liu Zeng Wen , Huang Bo
Published: July 2014

Micro-channels are widely used in many fields. There are a lot of burrs in the process of micro-channel machining, which affect the performance of micro-channels. In this study, some polishing experiments are conducted for the burr removal of micro-channels by the micro slurry jet on the home made micro slurry jet machining system. The morphology and the roughness of the micro-channels are measured. The factors to influence the burr removal and the micro-channel surface quality are analyzed in order to take measures to improve the surface quality. The results show that the micro slurry jet polishing not only removes the micro channel burrs, but also improves the micro channel surface quality. It is helpful to increase the flow of medium inside micro channel.
Study on Laser Cutting Carbon Fibre Reinforced Composites
Authors: Yang Li Jun , Hou Chao Jian , Chen Wei Qiang , Li Liang , Wang Yang
Published: July 2014

In order to solve the problem that delamination and bur will be easily produced in the process of the carbon fiber reinforced plastic (CFRP) composites, the cutting experiment of CFRP machined by pulsed Nd:YAG laser has been carried out. In the meantime, this paper investigates the mechanism of interaction between infrared laser and CFRP composite material and the quality of kerf influenced by different laser parameters and cutting directions. The study found that choosing appropriate laser parameters and cutting direction are effective means to get smaller heat affected zone (HAZ). This paper analysis the cross section morphology of kerf .The results show that the cross section does not appear stratified phenomenon and the surface is smooth, so the feasibility that infrared laser can be used to cut CFRP composites is verified.
Key Technology of Micro Electrochemical Milling Based on Ultra-Short Pulse Current
Authors: Li Xiao Hai , Sun Zhao Ning , Liu Wu Qi , Wang Xiao Xia
Published: July 2014

A new process of fabricating microstructures through micro electrochemical milling (micro EC milling) is proposed. The experiment equipment with a new type of ultra-short pulse supply was developed for micro EC milling. By controlling the movement track of simple micro tool electrode rotating at high speed on NC three-axis feed worktable, microstructures with high precision can be milled by micro-ECM under ultra-short pulse current. Micro EC milling can greatly improve the machining status in the tiny machining gap and thus make machining stable by simple rotary column electrode. The process of the NC generating micro-ECM integrating CAD/CAM technology is studied. G code for machining complex microstructures can be generated by the universal CAD/CAM of traditional milling based on UG software. Last, Microstructures with high precision were milled by this process, for example the micro trench with width of about 50μm.
Numerical Simulation to the Temperature Distribution of the Laser Cladding
Authors: Zhou Liang , Chen Xi , Zhu Bo
Published: July 2014

Numerical simulation to the temperature of laser cladding can simulate the process of its technique, which can also optimize the parameters of the technique and predict the defects of the cladding. In this paper, a three-dimensional finite element powder-feed laser single cladding model of the transient temperature field was built based on APDL in ANSYS, where the Gaussian distribution of heat source, forced convection heat transfer and the motion of laser heat source are simulated .The results reveal how the main technique parameters affect the distribution of the temperature, and make a prepare for the experiment of laser cladding.
Research on a Magnetic-Electrochemical Compound Polishing Head
Authors: Shi Li Min
Published: July 2014

In the paper, a new polishing head is researched and developed. How to set a magnetic feild is a key factor in magnetic-electrochemical compound polishing. To add a magnetic field that is parallel to electrical field, the electrochemical reaction can be changed greatly. Additionally, to add a magnetic field whose direction is changed to and fro, the efficiency of the polishing can be improved especially. In order to adapt to this theory, a new polishing head in magnec-electrochemical compound polishing is required resarch and development. Furthermore,the tool can be fixed on spindle of CNC easily and the tool is flexible so it can make the polishing head and workpiece touch evenly each other. Especially being noticed, the head of magnetic-electrochemical compound polishing tool is a series in order that the head can be replaced conveniently according to different surface. At last, the tool is tested and its function is perfect.
Thermal Analysis Simulation of a Single Pulse Laser Drilling Process
Authors: Zhu Bo , Tan Song Nian , Wang Yu Kui
Published: July 2014

A thermal model of a single pulse laser drilling process by using finite element method is presented. Some parameters such as conduction, convection, thermal properties of material with temperature and gauss distribution of heat flux has been considered in the laser drilling process. The simulation result shows the trend of dynamic temperature distribution of heat-affected zone, and by using the element birth and technique, the geometry size of the hole could be predicted in the simulation. Through the comparison between the simulation results and the actual experiment process results, the validity of the simulation model has been verified.
Investigations on the Machinability of Titanium Alloy TC25
Authors: Zhang Hong Shan , Ai Xing , Liu Zhan Qiang , Liu Ji Gang , Zhong Zhao Lin
Published: July 2014

Titanium alloy TC25 has been widely used in aircraft industry due to its excellent thermal stability, heat resistance and longer service life. In this paper, cemented carbide tools were applied to carry out orthogonal milling experiments for both titanium alloy TC25 and TC4 with identical cutting conditions. Cutting forces, cutting temperatures and surface roughness were measured to assess the machinability for TC25 and TC4. From the experimental results, the cutting parameters can be optimized to guide efficient machining processing of TC25.
Emerging therapies for osteoporosis
Authors: Minisola G. , Iuliano A. , Prevete I.
Published: July 2014

Currently available drugs for the treatment of osteoporosis can still be improved in terms of pharmacokinetics, pharmacodynamics and management. New approaches for the development of innovative drugs are possible thanks to our increasing understanding of the bone tissue biology and the cellular and molecular processes that regulate it. One of the new anti-bone resorption agents, odanacatib, a selective cathepsin-K inhibitor, is in late phase III clinical research. Among new bone anabolic drugs, those that have an action on the Wnt signaling pathway appear to be particularly promising. The development of new compounds for the treatment of osteoporosis represents an excellent example of translational medicine efforts aimed to extend the range of treatment options for osteoporosis, a very common disease with a high social and economic impact, particularly when causing fractures.
Osteoporosis and rheumatic diseases
Authors: Maruotti N. , Corrado A. , Cantatore F.P.
Published: July 2014

Numerous rheumatic diseases, including rheumatoid arthritis, juvenile idiopathic arthritis, psoriatic arthritis, ankylosing spondylitis, systemic lupus erythematosus, systemic sclerosis, dermatomyositis/polymyositis and vasculitis are characterized by osteoporosis and fragility fractures. Inflammatory cytokines, glucocorticoid treatment, immobilization and reduced physical activity due to painful joints and muscle weakness are considered the main risk factors that cause low body mass density values in these diseases. Emerging evidence highlights the role of inflammatory cytokines, such as tumor necrosis factor (TNF)-α, interleukin (IL)-1, IL-6, IL-7 and IL-17, in the regulation of the bone homeostasis. In fact, chronic inflammation is often characterized by an imbalance between bone formation and bone resorption with a net prevalence of osteoclastogenesis, which is an important determinant of bone loss in rheumatic diseases.
Male osteoporosis
Authors: Giusti A. , Bianchi G.
Published: July 2014

As a result of population ageing worldwide, osteoporotic fractures are becoming a serious problem in the western world. Osteoporotic fractures are associated with a significant burden in terms of morbidity, mortality, and economic costs. Although less frequent than in women, male osteoporosis is also a relatively common problem. Since bone loss and fragility fractures in men have been recognized as a serious medical condition, over the last two decades several studies have investigated a number of aspects related to the pathogenesis, diagnosis and assessment, prevention and treatment of male osteoporosis. A better understanding of factors underlying increased bone fragility in men has led to the definition of appropriate screening and diagnostic strategies, and the development of treatments that have shown to improve bone mineral density and, in some cases, reduce fracture risk in men as well as in women. This review will summarize recent findings on male osteoporosis with a particular focus on risk factors and causes of bone loss, and available therapeutic options.
Vitamin D and rheumatic diseases
Authors: Rossini M. , Gatti D. , Viapiana O. , Caimmi C. , Idolazzi L. , Fracassi E. , Adami S.
Published: July 2014

Vitamin D has some well-known effects on calcium, phosphate and bone metabolism, but it has recently shown to have many other effects, which may potentially be relevant to patients with extra-skeletal rheumatic diseases. Such effects may be justified by: 1) the presence of the vitamin D receptors also on extra-osseous cells, such as cartilage cells, sinoviocytes, muscle cells; 2) the proven role of vitamin D in the control of the transcription of genes involved in rheumatic diseases; 3) the evidence that vitamin D has multiple endocrine effects not only on calcium homeostasis; 4) the activation of vitamin D not only in the kidneys, but also in monocyte-macrophage and lymphocytic cell lines and in some epithelial cells with additional intracrine and paracrine effects. Vitamin D deficiency has been reported in numerous metabolic, degenerative, inflammatory and autoimmune rheumatic diseases. In some cases this association was also related to the risk of developing a rheumatic disease or the degree of disease activity. However there is no conclusive evidence of the efficacy of a preventive or therapeutic strategy based on vitamin D supplementation in extra-skeletal rheumatic diseases. This review aims to provide an overview of the latest evidence concerning the relationship between vitamin D and the most relevant rheumatic diseases.
Indicator mineral abundance data for bedrock and till from the Mount Pleasant Sn-W-Mo-Bi-In deposit, New Brunswick
Authors: McClenaghan M B , Parkhill M A , Averill S A , Pronk A G , Boldon R , Chapman J , Rice J
M
Published: July 2014

As part of the Geological Survey of Canada's Targeted Geoscience Initiative 4 (TGI-4) Program, till and bedrock samples were collected around the Mount Pleasant Sn-W-Mo-Bi-In deposit in southwest New Brunswick to determine the indicator minerals and their trace
element signatures that are indicative of intrusion-hosted polymetallic Sn-W deposits. The purpose of this open file is to report the raw indicator mineral weight and abundance data for bedrock and till samples collected in 2012 for this case study. Samples were processed by the commercial
laboratory Overburden Drilling Management Limited, Ottawa, ON, using a combination of tabling, panning, and heavy liquids to recover potential indicator minerals. Sample locations, weights of various fractions produced during sample processing, and indicator mineral grains identified are reported in
this open file. Interpretation of results will be presented in future publications.
Blood pressure control amongst patients living with hypertension presenting to an urban district hospital outpatient clinic in Kwazulu-Natal
Authors: Adebolu Folafolu A. , Naidoo Mergan
Published: July 2014

Background: The prevalence of hypertension in South Africa has been estimated to be 20% of the adult population with over six million people being affected. Poor adherence to treatment plans lead to inadequate blood pressure control and high morbidity. Many studies have looked at factors contributing to poor blood pressure control in South Africa but few studies actually focus on district hospitals in Kwazulu-Natal in particular, despite the fact that the province has the most heterogeneous population in South Africa.Method: The study was a descriptive cross-sectional study conducted at the chronic out patient clinic of an urban district hospital involving 370 participants aged 18–90 years.Result: The study showed poorly controlled blood pressure in 58% of the participants. Only 35% knew their blood pressure results on the day of interview and 19.2% were aware of their target blood pressure. Good adherence was self-reported by 95% of the participants, whist 51.4% reported significant side-effects to medication.Conclusion: The majority of patients had poor knowledge about blood pressure and little awareness of their blood pressure reading. These may be precursors to poor blood pressure control and this needs further investigation. A high level of self-reported adherence to medication did not translate into effective blood pressure control. A significant number reported medication side-effects which may have contributed to the poor blood pressure control. The high adherence rate may therefore have been over reported. An objective way tomeasure adherence will be necessary for future research.
Comparison of phenotype and differentiation marker gene expression profiles in human dental pulp and bone marrow mesenchymal stem cells
Authors: Ponnaiyan Deepa , Jegadeesan Visakan
Published: July 2014

Objective: Bone marrow (BM) is the most utilized and well-studied source of stem cells. Stem cells from dental tissues have provided an alternate source of mesenchymal stem cells (MSCs). Dental pulp stem cells (DPSCs) have been shown to share a similar pattern of protein expression with BMMSCs in vitro. However, differences have been noted between DPSCs and BMMSCs. This study focuses on variation in expression of stem cell and differentiation markers between DPSCs and BMMSCs. Materials and Methods: The two stem cells were isolated and compared for clonogenic potential, growth characteristics, multipotency, and stem cell marker expression. Specifically, the fatty acid binding protein 4, perilipin, alkaline phosphatase and osteonectic gene expression was analyzed by real-time polymerase chain reaction to confirm the capacity for adipogenic and osteogenic differentiation. Results: MSCs from these cell sources were similar in their morphology and immune phenotype except for the expression of CD105. Growth curves and colony formation assay revealed proliferation rate of DPSCs was significantly faster than BMMSCs (P < 0.05). DPSCs appeared less able to differentiate into adipogenic lineage, although more able to differentiate into osteogenic lineage. Conclusion: Data from the present study indicate how DPSCs are different from BMMSCs though they are a population of MSCs. DPSCs are a novel population of MSCs as observed by their unique expression of differentiation and lineage specific genes. Further microarray analysis could be used to determine, which genes are differentially regulated in BMMSCs and DPSCs to establish uniqueness of each population of MSCs.
In vitro bond strength and fatigue stress test evaluation of different adhesive cements used for fixed space maintainer cementation
Authors: Cantekin Kenan , Delikan Ebru , Cetin Secil
Published: July 2014

Objective: The purposes of this research were to (1) compare the shear-peel bond strength (SPBS) of a band of a fixed space maintainer (SM) cemented with five different adhesive cements; and (2) compare the survival time of bands of SM with each cement type after simulating mechanical fatigue stress. Materials and Methods: Seventy-five teeth were used to assess retentive strength and another 50 teeth were used to assess the fatigue survival time. SPBS was determined with a universal testing machine. Fatigue testing was conducted in a ball mill device. Results: The mean survival time of bands cemented with R & D series Nova Glass-LC (6.2 h), Transbond Plus (6.7 h), and R & D series Nova Resin (6.8 h) was significantly longer than for bands cemented with Ketac-Cem (5.4 h) and GC Equia (5.2 h) (P < 0.05). Conclusion: Although traditional glass ionomer cement (GIC) cement presented higher retentive strength than resin-based cements (resin, resin modified GIC, and compomer cement), resin based cements, especially dual cure resin cement (nova resin cement) and compomer (Transbond Plus), can be expected to have lower failure rates for band cementation than GIC (Ketac-Cem) in the light of the results of the ball mill test.
Effects of a bleaching agent with calcium on bovine enamel
Authors: Alexandrino Larissa , Gomes Yasmin , Alves Eliane , Costi Hilton , Rogez Hervé , Silva Cecy
Published: July 2014

Objective: This in vitro study analyzed the effects of a bleaching treatment containing 35% hydrogen peroxide (HP) with or without calcium on bovine enamel, using the Knoop hardness number (KHN), tristimulus colorimetry (TC), and scanning electron microscopy. Materials and Methods: Forty-five specimens were randomly divided into groups (n = 5), which included artificial saliva (negative control [NC]), 35% HP (positive control [PC]), and 35% HP Blue Calcium (HP Blue). The specimens were subjected to three bleaching sessions. During the sessions, the specimens were immersed in artificial saliva at 37°C. Before and after bleaching, KHN tests were conducted using a force of 25 gf for 5 s. TC was performed using the CIE-L*a*b* system and readouts were obtained at the following 4 time points: Before the bleaching treatment; after the first session, the second session, and the third session. The specimens were dehydrated and coated with gold, and the photomicrographs were analyzed in a double-blind manner with a LEO microscope. Results: Using one-way analysis of variance and Tukey's test (P < 0.05), a statistically significant difference was identified between the initial and final mean KHNs of the NC and PC groups, while the initial and final mean KHNs were not significantly different in the HP Blue group. The final mean values of ⋄E, ⋄L, and ⋄b of the PC and HP Blue groups were significantly higher than the initial values (P < 0.01 for both). The photomicrographs revealed no differences among the groups. Conclusions: Therefore, treatment with HP Blue prevented changes in the KHN without reducing the efficacy of bleaching.
Efficiency of the Self Adjusting File, WaveOne, Reciproc, ProTaper and hand files in root canal debridement
Authors: Topcu K. Meltem , Karatas Ertugrul , Ozsu Damla , Ersoy Ibrahim
Published: July 2014

Objectives: The aim of this study was to compare the canal debridement capabilities of three single file systems, ProTaper, and K-files in oval-shaped canals. Materials and Methods: Seventy-five extracted human mandibular central incisors with oval-shaped root canals were selected. A radiopaque contrast medium (Metapex; Meta Biomed Co. Ltd., Chungcheongbuk-do, Korea) was introduced into the canal systems and the self-adjusting file (SAF), WaveOne, Reciproc, ProTaper, and K-files were used for the instrumentation of the canals. The percentage of removed contrast medium was calculated using pre- and post-operative radiographs. Results: An overall comparison between the groups revealed that the hand file (HF) and SAF groups presented the lowest percentage of removed contrast medium, whereas the WaveOne group showed the highest percentage (P < 0.001). The ProTaper group removed more contrast medium than the SAF and HF groups (P < 0.05). Conclusions: None of the instruments was able to remove the contrast medium completely. WaveOne performed significantly better than other groups.
Does immediate dentin sealing influence the polymerization of impression materials?
Authors: Ghiggi Paula Cristine , Steiger Arno Kieling , Marcondes Maurem Leitão , Mota Eduardo Gonçalves , Burnett Luiz Henrique , Spohr Ana Maria
Published: July 2014

Objectives: The objective of the following study is to evaluate the interaction between the resin materials used in immediate dentin sealing (IDS) techniques and impression materials with two different techniques to eliminate the oxygen-inhibition layer. Materials and Methods: The occlusal dentin surface of 35 human molars was exposed. The teeth were used in two Groups: Group 1 – Impression with Express XT; Group 2 – Impression with Impregum. Groups 1 and 2 were divided into 14 subgroups: Groups 1a and 2a – Control groups; 1b and 2b – IDS with Clearfil SE Bond (CSE); 1c and 2c – IDS with CSE + additional polymerization with glycerin jelly; 1d and 2d – IDS with CSE + alcohol; 1e and 2e – IDS with CSE and Protect Liner F (PLF); 1f and 2f – IDS with CSE and PLF + additional polymerization with glycerin jelly; and 1g and 2g – IDS with CSE and PLF + alcohol. Five teeth were used in each experimental group, and the tooth surface was photographed using a digital camera. Results: Small quantity of unpolymerized impression material remained attached to the CSE or to the PLF in Groups 1b and 1e. Groups 1c and 1d prevented the interaction. Small quantity of polymerized impression material remained attached to the CSE or to the PLF for Groups 2b and 2e. The same interaction was observed for Groups 2c and 2d. For Groups 2c and 2f, no interactions were observed. Conclusion: Resin materials interacted with impression materials. The application of glycerin jelly and alcohol prevented the interaction of CSE with Express XT and PLF with Impregum; however, these treatments were not completely effective in preventing the interaction of CSE with Impregum and PLF with Express XT.
Relationship between orthodontic treatment and gingival health: A retrospective study
Authors: Boke Fatma , Gazioglu Cagri , Akkaya Sevil , Akkaya Murat
Published: July 2014

Objective: The aim of this retrospective study was to evaluate the relationship between orthodontic treatment and gingival health. Materials and Methods: A total of 251 patients among whom 177 were girls and 74 were boys, recruited from the records pool of the Department of Orthodontics, Faculty of Dentistry, University of Gazi, were included in the study. Patients’ treatments have been completed by postgraduate students during the period between 2006 and 2012. Patients’ folders were analyzed according to their age, treatment time, and the type of orthodontic treatment. Intra-oral photographs were analyzed, and the presence or absence of visible plaque, visible inflammation, and gingival recession were recorded, and incisor inclinations analyzed on lateral cephalometric films, before and after orthodontic treatment. Results: No statistically significant difference was found in patients treated with functional appliances before and after treatment. In patients treated with fixed orthodontic appliances, visible plaque, visible inflammation, and gingival recession showed significant increases after treatment, gingival biotype did not show any significant difference. Positive correlation was found between lower incisor position and gingival recession in patients treated with fixed appliance and extraction. And also cuspids were the teeth with the highest prevalence of gingival recession. Conclusion: Considering the relationship between orthodontic treatment and gingival health, cooperation among patients, orthodontists, and periodontists is important.
Comparison of anti-plaque efficacy between a low and high cost dentifrice: A short term randomized double-blind trial
Authors: Ganavadiya Rahul , Shekar B. R. Chandra , Goel Pankaj , Hongal Sudheer G. , Jain Manish , Gupta Ruchika
Published: July 2014

Objective: The aim of this study was to compare the anti-plaque efficacy of a low and high cost commercially available tooth paste among 13-20 years old adolescents in a Residential Home, Bhopal, India. Materials and Methods: The study was randomized double-blind parallel clinical trial conducted in a Residential Home, Bhopal, India. A total of 65 patients with established dental plaque and gingivitis were randomly assigned to either low cost or high cost dentifrice group for 4 weeks. The plaque and gingival scores at baseline and post-intervention were assessed and compared. Statistical analysis was performed using paired t-test and the independent sample t-test. The statistical significance was fixed at 0.05. Results: Results indicated a significant reduction in plaque and gingival scores in both groups post-intervention compared with the baseline. Difference between the groups was not significant. No adverse events were reported and both the dentifrices were well-tolerated. Conclusion: Low cost dentifrice is equally effective to the high cost dentifrice in reducing plaque and gingival inflammation.
Comparison of manual toothbrushes with different bristle designs in terms of cleaning efficacy and potential role on gingival recession
Authors: Cifcibasi Emine , Koyuncuoglu Cenker Zeki , Baser Ulku , Bozacioglu Busra , Kasali Kamber , Cintan Serdar
Published: July 2014

Objective: The aim was to compare the efficacy of plaque control and potential effects on gingival recession of the toothbrushes with angled and straight bristles. Materials and Methods: A total of 40 healthy dental students (25 females and 15 males; age range: 23-25 years) participated and two study groups were constituted. Participants were randomly distributed into two groups to use either angled or standard design manual tooth brushes with soft bristles. Oral hygiene indicators and soft tissue levels were monitored for 6 months. Plaque index, gingival index (GI), probing depth, clinical attachment level, and bleeding on probing were measured at six sites. Vertical recession (VR) and horizontal recession (HR) were also recorded. All measurements were repeated at 3 and 6 months. Results: Plaque scores were reduced significantly at 6 months compared to baseline in both groups (P < 0.05 and P < 0.005 in criss-cross and standard design brushes, respectively). Mean GI scores of the criss-cross design were reduced significantly at 6 months (P < 0.05). Inter-group comparisons revealed that gingival recession (GR) values were not statistically significant (P > 0.05) at baseline, 3 and 6 months suggesting no pronounced impact of bristle design in terms of GR (VR = 0.596, HR = 0.572; VR = 0.884, HR = 0.572; VR = 0.884, HR = 0.572 in the groups). Conclusions: Bristle design has little impact on plaque removal capacity of a toothbrush. Both designs are safe enough to prevent GR as long as soft bristle material is used.
Photodynamic therapy in combating the causative microorganisms from endodontic infections
Authors: de Oliveira Bruna Paloma , Aguiar Carlos Menezes , Câmara Andréa Cruz
Published: July 2014

Photodynamic therapy (PDT) is presented as a promising antimicrobial therapy that can eliminate microorganisms present in endodontic infections. This treatment is based on the use of a nontoxic photosensitizing agent followed by irradiation of a resonant light source being capable of generating highly reactive species that are harmful to microorganisms. The purpose of this paper is to review the dental literature about the main factors that encompass the use of PDT combined with endodontic treatment for decontamination of the root canal system. A literature search was performed using the following index databases: PubMed, ISI Web of Knowledge and MedLine, between 2000 and 2014, looking for studies regarding antimicrobial action of PDT and its application to endodontic therapy. It was observed that despite numerous promising results, it is still necessary to establish different parameters so that PDT can be used with maximum effectiveness in eliminating microorganisms that cause endodontic infections.
Sources and fate of nitrate in a groundwater‐fed estuary elucidated using stable isotope ratios of nitrogen and oxygen
Authors: Wong Wei Wen , Grace Michael R. , Cartwright Ian , Cook Perran L. M.
Published: July 2014

We used δ15N‐nitrate (NO−3) and δ18O‐NO−3 to unravel the provenance and fate of NO−3 in a groundwater‐fed estuary. A total of 13 monthly and two time series surveys were undertaken in the Werribee River estuary near Melbourne, Australia. The different survey timescales provided a comprehensive evaluation of the hydrological effects on the biogeochemistry of NO−3, which accounted for tidal variability and episodic runoff events. The distribution of δ15N and δ18O of the estuarine NO−3 along a mixing line between shallow and deep groundwater provided strong evidence for the predominance of groundwater‐derived NO−3 in the estuary. During dry periods when water residence time in the estuary was extended, shallow groundwater contributed 60% to 76% of the NO−3 (calculated from δ15N‐NO−3 and δ18O‐NO−3) to the estuary, and assimilation removed ∼ 70% of this groundwater‐derived NO−3. During wet periods, deep groundwater provided more (62%) NO−3 than shallow groundwater, and there was no indication of NO−3 consumption. Occasional sources of NO−3, which were also reflected by their δ15N‐NO−3 and δ18O‐NO−3 values, included NO−3 from nitrification and sewage‐derived NO−3 particularly at the bay entrance to the estuary. Greater emphasis should be placed upon the role of groundwater as a substantial NO−3 end member when assessing NO−3 biogeochemistry using methods relying on the dual isotopic composition of NO−3.
Parent-Child Interactions and Adolescent Anxiety: A Systematic Review
Authors: Waite Polly , Whittington Lauren , Creswell Cathy
Published: July 2014

Parental behaviours have been implicated in the development and maintenance of anxiety in children and young people; however the degree to which findings apply to adolescents specifically remains unclear. We conducted a systematic review of studies examining the evidence for an association between parental behaviours and adolescent anxiety. Twenty two studies were identified. The results of this systematic review provide fairly consistent preliminary evidence for an association between anxiety and perceived parental control and anxious rearing in adolescence. The findings relating to an association between adolescent anxiety and perceived parental rejection and lack of warmth are somewhat less consistent. Methodological shortcomings in the studies mean that these results should be interpreted with caution. Future research should be conducted using observational and experimental design with adolescents from referred, clinical populations to help identify the critical parental processes and clarify the direction of effects.
Stratospheric sudden warming effects on winds and temperature in the middle atmosphere at middle and low latitudes: a study using WACCM
Authors: Chandran A. , Collins R. L.
Published: July 2014

Abstract. A stratospheric sudden warming (SSW) is a dynamical phenomenon of the wintertime stratosphere caused by the interaction between planetary Rossby waves propagating from the troposphere and the stratospheric zonal-mean flow. While the effects of SSW events are seen predominantly in high latitudes, they can also produce significant changes in middle and low latitude temperature and winds. In this study we quantify the middle and low latitude effects of SSW events on temperature and zonal-mean winds using a composite of SSW events between 1988 and 2010 simulated with the specified dynamics version of the Whole Atmosphere Community Climate Model (WACCM). The temperature and wind responses seen in the tropics also extend into the low latitudes in the other hemisphere. There is variability in observed zonal-mean winds and temperature depending on the observing location within the displaced or split polar vortex and propagation direction of the planetary waves. The propagation of planetary waves show that they originate in mid–high latitudes and propagate upward and equatorward into the mid-latitude middle atmosphere where they produce westward forcing reaching peak values of ~ 60–70 m s−1 day−1. These propagation paths in the lower latitude stratosphere appear to depend on the phase of the quasi-biennial oscillation (QBO). During the easterly phase of the QBO, waves originating at high latitudes propagate across the equator, while in the westerly phase of the QBO, the planetary waves break at ~ 20–25° N and there is no propagation across the equator. The propagation of planetary waves across the equator during the easterly phase of the QBO reduces the tropical upwelling and poleward flow in the upper stratosphere.