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Yasser Alfawaz
AIM: The aim of this article is to evaluate the influence of finishing and polishing techniques on the surface roughness and microhardness of two composite resins with two different types of polishing systems. MATERIALS AND METHODS: A total of 30 disk-shaped specimens of nanocomposite Filtek™ Z350 and Ceram-X® were prepared. They were divided into three groups. The control group (n = 10) received no finishing and polishing. The remaining specimens were divided into two groups, and they received polishing and finishing either with PoGo or Sof-Lex system...
August 1, 2017: Journal of Contemporary Dental Practice
Jiang-Yuan Fan, Ting-Ting Lin, Fang-Xuan Hu, Rui-Bin Zheng, Fan Fan, Jian-Feng Ma
PURPOSE: To investigate the effect of sintering temperature on mechanical properties of dental zirconia toughened alumina (ZTA) ceramics prepared by gel-casting technique. METHODS: The samples prepared by gel-casting were sintered at 1100, 1200, 1250, 1300 and 1400degrees centigrade for each group. The flexural strength, fracture toughness, Vickers hardness and brittleness index were obtained and microscopic morphology of each group was observed under scanning electron microscope (SEM)...
April 2017: Shanghai Kou Qiang Yi Xue, Shanghai Journal of Stomatology
Zixu Yuan, Kelsey Baker, Mary W Redman, Lei Wang, Scott V Adams, Ming Yu, Brandon Dickinson, Karen Makar, Neli Ulrich, Jürgen Böhm, Michelle Wurscher, Maria Westerhoff, Steve Medwell, Ravi Moonka, Mika Sinanan, Alessandro Fichera, Kathy Vickers, William M Grady
BACKGROUND: Plasma microRNAs (miRNAs) are promising non-invasive biomarkers for colorectal cancer (CRC) prognosis. However, the published studies to date have yielded conflicting and inconsistent results for specific plasma miRNAs. METHODS: We have conducted a study using robust assays to assess a panel of nine miRNAs for CRC prognosis and early detection of recurrence. Plasma samples from 144 patients in a prospective CRC cohort study were collected at diagnosis, 6, 12, and 24 months after diagnosis...
August 15, 2017: British Journal of Cancer
Maryam Kazemipoor, Shaghayegh Azad, Farnaz Farahat
INTRODUCTION: The aim of the present study was to evaluate the concurrent effect of root canal preparation size and intra coronal bleaching on dentin microhardness. METHODS AND MATERIALS: Seventy-two intact anterior teeth were root canal treated and randomly divided into two groups (n=36) according to the size of coronal root canal preparation. The coronal portions of the canals were then enlarged with #2 and 4 Peeso reamers, respectively. Following root canal obturation, teeth were assigned into three groups (n=12) to be treated with bleaching agents containing 35% hydrogen peroxide (HP), sodium perborate (SP) and distilled water as control group...
2017: Iranian Endodontic Journal
Wei Li, Frank Liou, Joseph Newkirk, Karen M Brown Taminger, William J Seufzer
Joining titanium alloy and stainless steel is becoming an urgent need since their outstanding mechanical properties can be utilized integratedly. However, direct fusion joining of Ti6Al4V to SS316 can cause brittle Ti-Fe intermetallics which compromise join bonds' mechanical properties. In this research, Laser 3D Printing was applied to explore a new Ti6Al4V to SS316 multi-metallic structure. A novel filler transition route was introduced (Ti6Al4V → V → Cr → Fe → SS316) to avoid the Ti-Fe intermetallics...
August 11, 2017: Scientific Reports
Ruili Wang, Eric Habib, X X Zhu
OBJECTIVE: The aim of this work is to explore the reinforcing effect of wrinkled mesoporous silica (WMS), which should allow micromechanical resin matrix/filler interlocking in dental resin composites, and to investigate the effect of silica morphology, loading, and compositions on their mechanical properties. METHODS: WMS (average diameter of 496nm) was prepared through the self-assembly method and characterized by the use of the electron microscopy, dynamic light scattering, and the N2 adsorption-desorption measurements...
August 7, 2017: Dental Materials: Official Publication of the Academy of Dental Materials
Elwyn C Firth, Greg D Gamble, Jillian Cornish, Mark H Vickers
Alterations in the early life environment, including maternal undernutrition (UN) during pregnancy, can lead to increased risk of metabolic and cardiovascular disorders in offspring. Leptin treatment of neonates born to UN rats reverses the programmed metabolic phenotype, but the possible benefits of this treatment on bone tissue have not been defined. We describe for the first time the effects of neonatal leptin treatment on bone in adult offspring following maternal UN. Offspring from either UN or ad libitum-fed (AD) rats were treated with either saline or leptin (2...
August 9, 2017: Scientific Reports
Michelle Y Martin, Soumya J Niranjan, Raegan W Durant, Jennifer A Wenzel, Elise D Cook, Mona N Fouad, Selwyn M Vickers, Badrinath R Konety, Sarah B Rutland, Zachary R Simoni, Michelle Y Martin
The study of disparities in minority recruitment to cancer clinical trials has focused primarily on inquiries among minority patient populations. However, clinical trial recruitment is complex and requires a broader appreciation of the multiple factors that influence minority participation. One area that has received little attention is minority recruitment training for professionals who assume various roles in the clinical trial recruitment process. Therefore, we assessed the perspectives of cancer center clinical and research personnel on their training and education needs toward minority recruitment for cancer clinical trials...
August 3, 2017: Journal of Cancer Education: the Official Journal of the American Association for Cancer Education
Renata Borges Rodrigues, Carlos José Soares, Paulo Cézar Simamoto Junior, Vitor Carvalho Lara, Victor Elias Arana-Chavez, Veridiana Resende Novais
OBJECTIVES: The objective of this study was to evaluate the biomechanical properties of dentin and the microtensile bond strength (μTBS) performed before or after radiotherapy (RT). MATERIAL AND METHODS: Dentin chemical composition (infrared spectroscopy-FTIR), SEM images, and mechanical properties (Vickers microhardness-VHN and elastic modulus-E) were evaluated comparing no irradiated and irradiate dentin (n = 5). RT was defined by application of 72 Gy (1.8 Gy daily, 5 days per week, during 8 weeks) with sample immersed in distilled water...
August 4, 2017: Clinical Oral Investigations
Jun Wang, Hong Xu, Tiexiong Su, Yi Zhang, Zhen Guo, Huping Mao, Yangang Zhang
An investigation was carried out in order to study the fretting fatigue behavior of an AlSi9Cu2Mg aluminum alloy. The fretting fatigue tests of AlSi9Cu2Mg were performed using a specially designed testing machine. The failure mechanism of fretting fatigue was explored by studying the fracture surfaces, fretting scars, fretting debris, and micro-hardness of fretting fatigue specimens using scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), and micro Vickers hardness test techniques...
December 5, 2016: Materials
Luigi Alberto Ciro De Filippis, Livia Maria Serio, Francesco Facchini, Giovanni Mummolo, Antonio Domenico Ludovico
A simulation model was developed for the monitoring, controlling and optimization of the Friction Stir Welding (FSW) process. This approach, using the FSW technique, allows identifying the correlation between the process parameters (input variable) and the mechanical properties (output responses) of the welded AA5754 H111 aluminum plates. The optimization of technological parameters is a basic requirement for increasing the seam quality, since it promotes a stable and defect-free process. Both the tool rotation and the travel speed, the position of the samples extracted from the weld bead and the thermal data, detected with thermographic techniques for on-line control of the joints, were varied to build the experimental plans...
November 10, 2016: Materials
Xiao-Yu Ding, Lai-Ma Luo, Hong-Yu Chen, Xiao-Yong Zhu, Xiang Zan, Ji-Gui Cheng, Yu-Cheng Wu
Highly uniform oxide dispersion-strengthened materials W-1 wt % Nd₂O₃ and W-1 wt % CeO₂ were successfully fabricated via a novel wet chemical method followed by hydrogen reduction. The powders were consolidated by spark plasma sintering at 1700 °C to suppress grain growth. The samples were characterized by performing field emission scanning electron microscopy and transmission electron microscopy analyses, Vickers microhardness measurements, thermal conductivity, and tensile testing. The oxide particles were dispersed at the tungsten grain boundaries and within the grains...
October 28, 2016: Materials
Qun Wei, Quan Zhang, Haiyan Yan, Meiguang Zhang
Using the particle swarm optimization technique, we proposed a cubic superhard phase of C₃N (c-C₃N) with an estimated Vicker's hardness of 65 GPa, which is more energetically favorable than the recently proposed o-C₃N. The c-C₃N is the most stable phase in a pressure range of 6.5-15.4 GPa. Above 15.4 GPa, the most energetic favorable high pressure phase R3m-C₃N is uncovered. Phonon dispersion and elastic constant calculations confirm the dynamical and mechanical stability of c-C₃N and R3m-C₃N at ambient pressure...
October 17, 2016: Materials
Yongchang Liu, Yi Shao, Chenxi Liu, Yan Chen, Dantian Zhang
The mechanical properties of the high-strength low-alloy pipeline steels were mainly controlled by the subsequent phase transformations after rolling. The influence of hot uniaxial compression on the phase transformation of acicular ferrite was explored by viewing of the deformation degree, the deformation temperature, and the strain rate. The results show that the increase of deformation amounts raises the transformation starting and finishing temperature during the subsequent cooling and also promotes the polygonal ferrite transformation, which leads to the decrease of Vickers hardness accordingly...
August 24, 2016: Materials
Jing An, Jinpeng Song, Guoxing Liang, Jiaojiao Gao, Juncai Xie, Lei Cao, Shiying Wang, Ming Lv
The effects of HfB₂ and HfN additions on the microstructures and mechanical properties of TiB₂-based ceramic tool materials were investigated. The results showed that the HfB₂ additive not only can inhibit the TiB₂ grain growth but can also change the morphology of some TiB₂ grains from bigger polygons to smaller polygons or longer ovals that are advantageous for forming a relatively fine microstructure, and that the HfN additive had a tendency toward agglomeration. The improvement of flexural strength and Vickers hardness of the TiB₂-HfB₂ ceramics was due to the relatively fine microstructure; the decrease of fracture toughness was ascribed to the formation of a weaker grain boundary strength due to the brittle rim phase and the poor wettability between HfB₂ and Ni...
April 27, 2017: Materials
Felix Rickhey, Karuppasamy Pandian Marimuthu, Hyungyil Lee
Vickers indentation fracture can be used to estimate equibiaxial residual stresses (RS) in brittle materials. Previous, conceptually-equal, analytical models were established on the assumptions that (i) the crack be of a semi-circular shape and (ii) that the shape not be affected by RS. A generalized analytical model that accounts for the crack shape and its change is presented. To assess these analytical models and to gain detailed insight into the crack evolution, an extended finite element (XFE) model is established...
April 12, 2017: Materials
Zhongfa Mao, David Z Zhang, Peitang Wei, Kaifei Zhang
Copper alloys, combined with selective laser melting (SLM) technology, have attracted increasing attention in aerospace engineering, automobile, and medical fields. However, there are some difficulties in SLM forming owing to low laser absorption and excellent thermal conductivity. It is, therefore, necessary to explore a copper alloy in SLM. In this research, manufacturing feasibility and forming properties of Cu-4Sn in SLM were investigated through a systematic experimental approach. Single-track experiments were used to narrow down processing parameter windows...
March 24, 2017: Materials
José C González, Miguel Á Rodríguez, Ignacio A Figueroa, María-Elena Villafuerte-Castrejón, Gerardo C Díaz
The synthesis of AlN and TiB₂ by spark plasma sintering (SPS) and the effect of Nb₂O₅, Y₂O₃ and ZrO₂ additions on the mechanical properties and densification of the produced composites is reported and discussed. After the SPS process, dense AlN and TiB₂ composites with Nb₂O₅, Y₂O₃ and ZrO₂ were successfully prepared. X-ray diffraction analysis showed that in the AlN composites, the addition of Nb₂O₅ gives rise to Nb₄N₃ during sintering. The compound Y₃Al₅O12 (YAG) was observed as precipitate in the sample with Y₂O₃...
March 22, 2017: Materials
Stanisław Fic, Andrzej Szewczak, Danuta Barnat-Hunek, Grzegorz Łagód
The article presents a proposal of a model of fatigue destruction of hydrophobised ceramic brick, i.e., a basic masonry material. The brick surface was hydrophobised with two inorganic polymers: a nanopolymer preparation based on dialkyl siloxanes (series 1-5) and an aqueous silicon solution (series 6-10). Nanosilica was added to the polymers to enhance the stability of the film formed on the brick surface. To achieve an appropriate blend of the polymer liquid phase and the nano silica solid phase, the mixture was disintegrated by sonication...
January 6, 2017: Materials
B M Assis, L A F Silva, C R O Lima, R F Gouveia, V A S Vulcani, F J F de Sant'Ana, R E Rabelo
The aim of this study was to describe the microstructure of hoof capsules of the buffalo. In addition, the study emphasized the morphometric aspects of the horn tubules, the Vickers nanohardness of the dorsal and abaxial walls and sole of the digits of the thoracic and pelvic limbs of the buffalo. The abaxial wall in the thoracic and pelvic digits showed larger diameter of the horn tubules when compared to all dorsal wall and sole. In addition, the abaxial wall of the thoracic digits showed larger diameter of the horn tubules when compared with the pelvic digits...
July 31, 2017: Anatomia, Histologia, Embryologia
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