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Maria Pfeilschifter, Verena Preis, Michael Behr, Martin Rosentritt
OBJECTIVES: To investigate the edge force of CAD/CAM materials as a function of (a) material, (b) thickness, and (c) distance from the margin. METHODS: Materials intended for processing with CAD/CAM were investigated: eight resin composites, one resin-infiltrated ceramic, and a clinically proven lithiumdisilicate ceramic (reference). To measure edge force (that is, load to failure/crack), plates (d = 1 mm) were fixed and loaded with a Vickers diamond indenter (1 mm/min, Zwick 1446) at a distance of 0...
May 16, 2018: Journal of Dentistry
Ramin Aghababaei, Tobias Brink, Jean-François Molinari
Wear is the inevitable damage process of surfaces during sliding contact. According to the well-known Archard's wear law, the wear volume scales with the real contact area and as a result is proportional to the load. Decades of wear experiments, however, show that this relation only holds up to a certain load limit, above which the linearity is broken and a transition from mild to severe wear occurs. We investigate the microscopic origins of this breakdown and the corresponding wear transition at the asperity level...
May 4, 2018: Physical Review Letters
María Jesús Gómez, Eduardo Corral, Cristina Castejón, Juan Carlos García-Prada
Crack detection for railway axles is key to avoiding catastrophic accidents. Currently, non-destructive testing is used for that purpose. The present work applies vibration signal analysis to diagnose cracks in real railway axles installed on a real Y21 bogie working on a rig. Vibration signals were obtained from two wheelsets with cracks at the middle section of the axle with depths from 5.7 to 15 mm, at several conditions of load and speed. Vibration signals were processed by means of wavelet packet transform energy...
May 17, 2018: Sensors
Lei Zhang, Yue-Hua Liu, Kai-Yu Luo, Yong-Kang Zhang, Yong Zhao, Jian-Yun Huang, Xu-Dong Wu, Chuang Zhou
Tensile property was one important index of mechanical properties of ANSI 304 stainless steel laser weldments subjected to cavitation erosion (CE). Laser shock processing (LSP) was utilized to strengthen the CE resistance, and the tensile property and fracture morphology were analyzed through three replicated experiment times. Results showed tensile process of treated weldments was composed of elastic deformation, plastic deformation, and fracture. The elastic limit, elastic modulus, elongation, area reduction, and ultimate tensile strength of tensile sample after CE were higher in view of LSP...
May 16, 2018: Materials
Typhanye V Dyer, Maria R Khan, Rotrease Regan, Nina T Harawa, LaRon E Nelson, Leo Wilton, Lei Wang, Lili Peng, San San Ou, Steve Shoptaw
BACKGROUND: Black men who have sex with men (BMSM); some who also have sex with women (BMSMW), account for over 70% of new HIV infections in the US representing an elevated HIV risk in this group, also informing risks for HIV transmission to other BMSM and female sexual partners. SETTINGS: We examined trajectories of self-reported substance use, HIV-related sexual risk behaviors and psychosocial vulnerabilities among BMSMW versus BMSM over a one-year study period...
May 10, 2018: Journal of Acquired Immune Deficiency Syndromes: JAIDS
Hina Shah, Pablo Hernandez, Francois Budin, Deepak Chittajallu, Jean-Baptiste Vimort, Rick Walters, André Mol, Asma Khan, Beatriz Paniagua
Studies show that cracked teeth are the third most common cause for tooth loss in industrialized countries. If detected early and accurately, patients can retain their teeth for a longer time. Most cracks are not detected early because of the discontinuous symptoms and lack of good diagnostic tools. Currently used imaging modalities like Cone Beam Computed Tomography (CBCT) and intraoral radiography often have low sensitivity and do not show cracks clearly. This paper introduces a novel method that can detect, quantify, and localize cracks automatically in high resolution CBCT (hr-CBCT) scans of teeth using steerable wavelets and learning methods...
February 2018: Proceedings of SPIE
Erwei Nie, Jiao Yu, Debaditya Dutta, Yanying Zhu
BACKGROUND: Liver trauma is an important source of morbidity and mortality worldwide. A timely detection and precise evaluation of traumatic liver injury and the bleeding site is necessary. There is a need to develop better imaging modalities of hepatic injuries to increase the sensitivity of ultrasonic imaging techniques for sites of hemorrhage caused by cracks. In this study, we conduct an in silico simulation of liver crack detection and delineation using an ultrasonic shear wave imaging (USWI) based method...
May 16, 2018: BMC Medical Imaging
Érika Barbosa de Oliveira Silva, Adriana Lenho de Figueiredo Pereira, Lúcia Helena Garcia Penna
The study analyzed health professionals' conceptions toward female users of crack and powder cocaine currently receiving psychosocial care, based on a gender perspective. Seventeen health professionals were interviewed, and systematic observations were made of the spaces for collective care in a Center for Psychosocial Care specializing in alcohol and drug addiction in Greater Metropolitan Rio de Janeiro, Brazil. Analysis of the interviews and field diaries using the hermeneutic-dialectic method revealed three categories: frailty as a constitutive attribute of women's condition, the women's emotional addiction to crack and powder cocaine use, and gender stereotypes during psychosocial care...
May 10, 2018: Cadernos de Saúde Pública
Xiaoyu Ji, Shanshan Wang, Changwei Shao, Hao Wang
Amorphous SiBCN fibers possessing superior stability against oxidation have become a desirable candidate for the high-temperature aerospace applications. Currently, investigations on the high-temperature corrosion behavior of these fibers for the application in high-heat engines are insufficient. Here, our polymer-derived SiBCN fibers were corroded at 1400 °C in air and simulated combustion environments, respectively. The fibers' structural evolution after corrosion in two different conditions and the potential mechanisms are investigated...
May 16, 2018: ACS Applied Materials & Interfaces
Daiani Modernel Xavier, Giovana Calcagno Gomes, Juliane Portella Ribeiro, Marina Soares Mota, Simone Quadros Alvarez
OBJECTIVES: To know the effects for the newborn of the use of crack in pregnancy. METHODS: This is a qualitative study conducted in a university hospital in southern Brazil, in the first half of 2014. Fifteen mothers crack users and five grandparents participated. The data were produced through semi-structured interviews and later submitted to content analysis. RESULTS: It was found that the use of crack in pregnancy leads to repercussions related to the health of the newborn and repercussions related to family restructuring...
October 2017: Investigación y Educación en Enfermería
Kristine F Frederiksen, Kacper Januchta, Nerea Mascaraque, Randall E Youngman, Mathieu Bauchy, Sylwester J Rzoska, Michal Bockowski, Morten M Smedskjaer
Alkali aluminoborate glasses have recently been shown to exhibit a very high threshold for indentation cracking compared to other bulk oxide glasses. However, to enable the use of these materials in engineering applications, there is a need to improve their hardness by tuning the chemical composition. In this study, we substitute alkaline earth for alkali network-modifying species at fixed aluminoborate base glass composition and correlate it with changes in structure, mechanical properties, and densification behavior...
May 16, 2018: Journal of Physical Chemistry. B
Huawei Liu, Liping Wu, Ekaterina Nikolaeva, Kari Peter, Zongrang Liu, Dimitre Mollov, Mengji Cao, Ruhui Li
BACKGROUND: 'Rapid Apple Decline' (RAD) is a newly emerging problem of young, dwarf apple trees in the Northeastern USA. The affected trees show trunk necrosis, cracking and canker before collapse in summer. In this study, we discovered and characterized a new luteovirus from apple trees in RAD-affected orchards using high-throughput sequencing (HTS) technology and subsequent Sanger sequencing. METHODS: Illumina NextSeq sequencing was applied to total RNAs prepared from three diseased apple trees...
May 15, 2018: Virology Journal
Marta Vila-Cortavitarte, Daniel Jato-Espino, Daniel Castro-Fresno, Miguel Á Calzada-Pérez
Major advances have been achieved in the field of self-healing by magnetic induction in which the addition of metallic particles into asphalt mixtures enables repairing their own cracks. This technology has already been proven to increase the life expectancy of roads. Nevertheless, its higher costs in comparison with conventional maintenance caused by the price of virgin metallic particles still makes it unattractive for investment. This research aimed at making this process economically accessible as well as environmentally efficient...
May 15, 2018: Materials
Jicheng Zhang, Yongshui Huang, Yu Zheng
In recent years, piezoelectric-based transducers and technologies have made significant progress towards structural health monitoring and damage evaluation for various metal and concrete structures. Timber is still commonly used as a construction material in practical engineering; however, there is a lack of research on the health monitoring of timber-based structures using piezoelectric-based transducers and methods. This paper conducts a feasibility study on timber damage detection using surface-mounted piezoelectric patches, which enable the stress-wave-based active sensing approach...
May 15, 2018: Sensors
Abe DeAnda, Leora B Balsam
No abstract text is available yet for this article.
April 16, 2018: Journal of Thoracic and Cardiovascular Surgery
Anahit Galstyan, Angela Hay
There is an increasing appreciation for the role of physical forces in plant development. Mechanics are fundamental to how explosive fruit eject their seeds, and recent studies have successfully combined mechanics with developmental genetics to help explain how these dispersal traits are produced and how they evolved. Computational modeling is used more and more to address developmental questions, and explosive fruit are particularly good systems for combining biology and modeling approaches. Finite element models have been recently used to explore questions such as: Why do touch-me-not species with similar fruits, differ so much in how efficiently they transfer stored energy to eject seeds? And how do popping cress fruits use the expansive force of turgor pressure for tissue contraction?...
May 9, 2018: Current Opinion in Genetics & Development
Zhihui Zhang, Lan Zhang, Zhenglei Yu, Jingjing Liu, Xiujuan Li, Yunhong Liang
In natural biological systems, many insects in complex environments exhibit exemplary mechanical properties. Dragonfly wings are light and strong enough to withstand wind loading. Their rigid veins play supporting and strengthening roles to enhance resistance to fatigue. To explore the effect of veins on arresting cracking in the wing, the costa, subcosta, radius R1, and two areas of dragonfly hind wings were samples for in situ tensile tests. The fracture process of the samples was observed with a high-speed camera and a scanning electron microscope...
May 5, 2018: Micron: the International Research and Review Journal for Microscopy
Chaohua Yang, Gaoju Wang, Fenfen Ma, Baoqing Yu, Fancheng Chen, Jin Yang, Jianjun Feng, Qing Wang
BACKGROUND: Spinal cord injuries (SCIs) are sustained by an increasing number of patients each year worldwide. The treatment of SCIs has long been a hard nut to crack for doctors around the world. Mesenchymal stem cells (MSCs) have shown benefits for the repair of SCI and recovery of function. Our present study aims to investigate the effects of intravenously infused human umbilical cord blood-derived MSCs (hUCB-MSCs) on functional recovery after subacute spinal cord compression injury of two noncontinuous segments...
May 11, 2018: Stem Cell Research & Therapy
Hyeong Min Son, Ha Yeon Kim, Sol Moi Park, Haeng Ki Lee
The present study investigated the CaCO₃ precipitation performance of ureolytic and non-ureolytic bacteria co-cultured as a self-healing agent for cementitious materials crack repair. Three different inoculum ratios of ureolytic Sporosarcina pasteurii and non-ureolytic Bacillus thuringiensis (10:0, 8:2, or 5:5) were used. The effect of coculturing ureolytic and non-ureolytic bacteria on microbial metabolism was investigated by measuring the rate of growth in urea-containing medium and the rate of NH₄⁺ and CaCO₃ production in urea⁻calcium lactate medium...
May 11, 2018: Materials
Hongxun Wang, Weifang Zhang, Jingyu Zhang, Wei Dai, Yan Zhao
In-situ scanning electron microscopy (SEM) testing based on a small time scale is proposed to integrally investigate the fatigue crack growth behavior and mechanisms, which is different from the widely-used, cycle-based approach due to its small time scale and comprehensive analysis of the effects of microstructure, crack closure and applied loading on crack growth. In the proposed methodology, the behavior of fatigue crack growth at any time within a loading cycle is observed by SEM to investigate the influence of microstructure on crack growth...
May 11, 2018: Materials
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