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https://www.readbyqxmd.com/read/28441738/simulation-study-of-the-localization-of-a-near-surface-crack-using-an-air-coupled-ultrasonic-sensor-array
#1
Steven Delrue, Vladislav Aleshin, Mikael Sørensen, Lieven De Lathauwer
The importance of Non-Destructive Testing (NDT) to check the integrity of materials in different fields of industry has increased significantly in recent years. Actually, industry demands NDT methods that allow fast (preferably non-contact) detection and localization of early-stage defects with easy-to-interpret results, so that even a non-expert field worker can carry out the testing. The main challenge is to combine as many of these requirements into one single technique. The concept of acoustic cameras, developed for low frequency NDT, meets most of the above-mentioned requirements...
April 22, 2017: Sensors
https://www.readbyqxmd.com/read/28441274/-meth-mouth-an-interdisciplinary-review-of-a-dental-and-psychiatric-condition
#2
Cornel N Stanciu, Magdalena Glass, Brian C Muzyka, Oliver M Glass
OBJECTIVE: Chronic methamphetamine (MA) users experience many dental problems, a condition characterized as "meth mouth." These devastating effects on dentition is the main reason why many seek professional help. Here, we discuss the effects of MA on oral health and advocate for improved collaboration between dentists and mental health providers. We also introduce a dental evaluation tool with the goal of improving the quality of care for this often-marginalized patient population. METHODS: A Medline literature search (1985-2016) was conducted with keywords "meth mouth," "methamphetamine AND oral health"; "methamphetamine AND dental"; "methamphetamine AND dentist...
April 24, 2017: Journal of Addiction Medicine
https://www.readbyqxmd.com/read/28439069/drying-mediated-patterns-in-colloid-polymer-suspensions
#3
Seul-A Ryu, Jin Young Kim, So Youn Kim, Byung Mook Weon
Drying-mediated patterning of colloidal particles is a physical phenomenon that must be understood in inkjet printing technology to obtain crack-free uniform colloidal films. Here we experimentally study the drying-mediated patterns of a model colloid-polymer suspension and specifically observe how the deposit pattern appears after droplet evaporation by varying particle size and polymer concentration. We find that at a high polymer concentration, the ring-like pattern appears in suspensions with large colloids, contrary to suppression of ring formation in suspensions with small colloids thanks to colloid-polymer interactions...
April 24, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28438007/high-speed-cleaving-of-crystals-with-ultrafast-bessel-beams
#4
L Rapp, R Meyer, L Furfaro, C Billet, R Giust, F Courvoisier
We develop a novel concept for ultra-high speed cleaving of crystalline materials with femtosecond lasers. Using Bessel beams in single shot, fracture planes can be induced nearly all along the Bessel zone in sapphire. For the first time, we show that only for a pulse duration below 650 fs, a single fracture can be induced in sapphire, while above this duration, cracks appear in all crystallographic orientations. We determine the influential parameters which are polarization direction, crystallographic axes and scanning direction...
April 17, 2017: Optics Express
https://www.readbyqxmd.com/read/28437778/strengthening-governance-for-intertidal-ecosystems-requires-a-consistent-definition-of-boundaries-between-land-and-sea
#5
Stefanie M Rog, Carly N Cook
The protection of intertidal ecosystems is complex because they straddle both marine and terrestrial realms. This leads to inconsistent characterisation as marine and/or terrestrial systems, or neither. Vegetated intertidal ecosystems are especially complex to classify because they can have an unclear border with terrestrial vegetation, causing confusion around taxonomy (e.g., mangrove-like plants). This confusion and inconsistency in classification can impact these systems through poor governance and incomplete protection...
April 21, 2017: Journal of Environmental Management
https://www.readbyqxmd.com/read/28435364/influence-of-reuse-and-cervical-preflaring-on-the-fracture-strength-of-reciprocating-instruments
#6
Claudio Maniglia-Ferreira, Fabio de Almeida Gomes, Tatyana Ximenes, Murilo Alves Teixeira Neto, Thiane Elys Arruda, Giovani Gonçalves Ribamar, Luis Flávio Gaspar Herculano
OBJECTIVE: This study sought to assess the influence of cervical preflaring and reuse after resterilization, on fracture strength and plastic deformation and/or surface cracking in reciprocating nickel-titanium [NiTi] endodontic instruments after root canal instrumentation of extracted human teeth. MATERIALS AND METHODS: Forty engine-driven reciprocating NiTi instruments (20 Reciproc(®) [RC], VDW; 20 WaveOne(®) [WO], Dentsply) were used in root canal instrumentation of extracted human molars...
January 2017: European Journal of Dentistry
https://www.readbyqxmd.com/read/28435332/lacquer-cracks-observed-in-peripheral-fundus-of-eyes-with-high-myopia
#7
Mitsuki Suga, Kosei Shinohara, Kyoko Ohno-Matsui
We report a case with lacquer cracks observed in the peripheral fundus. A 37-year-old patient with bilateral high myopia who visited our clinic was examined by fluorescein angiography (FA) and fundus autofluorescence (FAF) to determine whether there were myopic fundus lesions. FA showed many arch-shaped, hyperfluorescent linear lesions running circumferentially in the peripheral fundus. FAF showed hypo-autofluorescence at the corresponding sites. These characteristics were very similar to the lacquer cracks present in the posterior fundus in highly myopic eyes...
2017: International Medical Case Reports Journal
https://www.readbyqxmd.com/read/28434434/local-structural-damage-evaluation-of-a-c-c-sic-ceramic-matrix-composite
#8
Benedicta D Arhatari, Matthew Zonneveldt, John Thornton, Brian Abbey
Ceramic matrix composites (CMCs) are structural materials, which have useful properties that combine high strength at high temperatures with moderate toughness. Carbon fibers within a matrix of carbon and silicon carbide, called C/C-SiC, are a particular class of CMC noted for their high oxidation resistance. Here we use a combination of four-point bending and X-ray radiography, to study the mechanical failure of C/C-SiC CMCs. Correlating X-ray radiographic and load/displacement curve data reveals that the fiber bundles act to slow down crack propagation during four-point bending tests...
April 24, 2017: Microscopy and Microanalysis
https://www.readbyqxmd.com/read/28433886/controlled-release-of-metformin-from-chitosan-based-nanocomposite-films-containing-mesoporous-mcm-41-nanoparticles-as-novel-drug-delivery-systems
#9
Zahra Shariatinia, Zahra Zahraee
Biocompatible nanocomposite films based on blended chitosan and poly(ethylene glycol)-block-poly(propylene glycol)-block-poly(ethylene glycol) (BP) polymers containing metformin (MET) drug and MCM-41 or MCM-41-APS (APS=aminopropylsilane) nanoparticles (NPs) were designed and fabricated in order to prepare novel drug delivery systems which are useful for controlled drug release purposes. The total pore volume and mesopore volume of MCM-41 were measured equal to 1.08 and 1.05 cm(3)/g but those of MCM-41-APS were 0...
April 13, 2017: Journal of Colloid and Interface Science
https://www.readbyqxmd.com/read/28433810/generation-mechanism-of-nonlinear-ultrasonic-lamb-waves-in-thin-plates-with-randomly-distributed-micro-cracks
#10
Youxuan Zhao, Feilong Li, Peng Cao, Yaolu Liu, Jianyu Zhang, Shaoyun Fu, Jun Zhang, Ning Hu
Since the identification of micro-cracks in engineering materials is very valuable in understanding the initial and slight changes in mechanical properties of materials under complex working environments, numerical simulations on the propagation of the low frequency S0 Lamb wave in thin plates with randomly distributed micro-cracks were performed to study the behavior of nonlinear Lamb waves. The results showed that while the influence of the randomly distributed micro-cracks on the phase velocity of the low frequency S0 fundamental waves could be neglected, significant ultrasonic nonlinear effects caused by the randomly distributed micro-cracks was discovered, which mainly presented as a second harmonic generation...
April 12, 2017: Ultrasonics
https://www.readbyqxmd.com/read/28433536/assessment-of-enamel-cracks-at-adhesive-cavosurface-margin-using-three-dimensional-swept-source-optical-coherence-tomography
#11
Tomoko Tabata, Yasushi Shimada, Alireza Sadr, Junji Tagami, Yasunori Sumi
OBJECTIVES: Swept-source optical coherence tomography (SS-OCT) can construct cross-sectional images of internal biological structures. The aim of this study was to evaluate enamel cracks at the cavosurface margin of composite restorations using SS-OCT. METHODS: Bowl-shaped cavities were prepared at two locations (mid-coronal and cervical regions) on the enamel surface of 60 bovine teeth. Half of the cavities (30) were treated with phosphoric acid gel. A two-step self-etch adhesive (Clearfil SE Bond) was applied to all cavities and a flowable composite was placed in bulk...
April 19, 2017: Journal of Dentistry
https://www.readbyqxmd.com/read/28433166/chitosan-graphene-oxide-films-and-co2-dried-porous-aerogel-microspheres-interfacial-interplay-and-stability
#12
Sana Frindy, Ana Primo, Hamid Ennajih, Abou El Kacem Qaiss, Rachid Bouhfid, Mohamed Lahcini, El Mokhtar Essassi, Hermenegildo Garcia, Abdelkrim El Kadib
The intimate interplay of chitosan (CS) and graphene oxide (GO) in aqueous acidic solution has been explored to design upon casting, nanostructured "brick-and-mortar" films (CS-GO-f) and by acidic-to-basic pH inversion, porous CO2-dried aerogel microspheres (CS-GO-m). Owing to the presence of oxygenated functional groups in GO, good-quality crack-free hybrid films were obtained. Mechanical properties were improved independently of the GO content and it was found that a 20wt% loading affords hybrid film characterized with a Young modulus three times superior to that reached with the same loading of layered clay...
July 1, 2017: Carbohydrate Polymers
https://www.readbyqxmd.com/read/28430081/prevalence-and-factors-associated-with-criminal-behavior-among-illicit-drug-users-a-cross-sectional-study
#13
Rafael Alves Guimarães, Natália Silva Mesquita, Renata Silva Lopes, Roselma Lucchese, Rodrigo Lopes de Felipe, Ivânia Vera, Inaina Lara Fernandes, Paulo Alexandre de Castro, Luiz Henrique Batista Monteiro, Graciele Cristina Silva
BACKGROUND: Studies indicate high rates of criminal behavior, violent activities, and legal problems among illicit drug users (IDU) in Brazil. The aim of this study was to estimate the prevalence and factors associated with criminal behavior among IDU undergoing treatment for chemical dependency in Central Brazil. METHODS: Cross-sectional study carried out with IDU undergoing treatment for chemical dependence. Data were collected by means of face-to-face interviews and analyzed using logistic regression...
April 21, 2017: Substance Use & Misuse
https://www.readbyqxmd.com/read/28429875/effect-of-untreated-zirconium-oxide-nanofiller-on-the-flexural-strength-and-surface-hardness-of-autopolymerized-interim-fixed-restoration-resins
#14
Abdolhamid Alhavaz, Maryam Rezaei Dastjerdi, Arman Ghasemi, Azade Ghasemi, Abolfazl Alizadeh Sahraei
OBJECTIVE: Autopolymerized poly methyl methacrylate (PMMA) resin is commonly used for the construction of interim restorations; however, it has less than optimal mechanical properties. In this article, we evaluated the reinforcing effect of adding untreated zirconia nanoparticles on the flexural strength and surface hardness of this resin. METHODS: A total of 80 specimens were fabricated. Forty each were used for the flexural strength test and for the surface hardness test...
April 21, 2017: Journal of Esthetic and Restorative Dentistry
https://www.readbyqxmd.com/read/28429506/a-robust-and-conductive-black-tin-oxide-nanostructure-makes-efficient-lithium-ion-batteries-possible
#15
Wujie Dong, Jijian Xu, Chao Wang, Yue Lu, Xiangye Liu, Xin Wang, Xiaotao Yuan, Zhe Wang, Tianquan Lin, Manling Sui, I-Wei Chen, Fuqiang Huang
SnO2 -based lithium-ion batteries have low cost and high energy density, but their capacity fades rapidly during lithiation/delithiation due to phase aggregation and cracking. These problems can be mitigated by using highly conducting black SnO2-x , which homogenizes the redox reactions and stabilizes fine, fracture-resistant Sn precipitates in the Li2 O matrix. Such fine Sn precipitates and their ample contact with Li2 O proliferate the reversible Sn → Li x Sn → Sn → SnO2 /SnO2-x cycle during charging/discharging...
April 21, 2017: Advanced Materials
https://www.readbyqxmd.com/read/28429484/interaction-between-endodontics-and-periodontics
#16
REVIEW
Ilan Rotstein
Endodontic-periodontal lesions present challenges to the clinician regarding diagnosis, treatment planning and prognosis. Etiologic factors, such as bacteria and viruses, as well as contributing factors, such as trauma, root resorptions, perforations, cracks and dental malformations, play an important role in the development and progression of such lesions. Treatment and prognosis of endodontic-periodontal lesions vary, depending on the etiology, pathogenesis and correct diagnosis of each specific condition...
June 2017: Periodontology 2000
https://www.readbyqxmd.com/read/28427837/in-vitro-fatigue-tests-and-in-silico-finite-element-analysis-of-dental-implants-with-different-fixture-abutment-joint-types-using-computer-aided-design-models
#17
Satoshi Yamaguchi, Yasufumi Yamanishi, Lucas S Machado, Shuji Matsumoto, Nick Tovar, Paulo G Coelho, Van P Thompson, Satoshi Imazato
PURPOSE: The aim of this study was to evaluate fatigue resistance of dental fixtures with two different fixture-abutment connections by in vitro fatigue testing and in silico three-dimensional finite element analysis (3D FEA) using original computer-aided design (CAD) models. METHODS: Dental implant fixtures with external connection (EX) or internal connection (IN) abutments were fabricated from original CAD models using grade IV titanium and step-stress accelerated life testing was performed...
April 17, 2017: Journal of Prosthodontic Research
https://www.readbyqxmd.com/read/28427678/application-and-mechanism-of-ultrasonic-static-mixer-in-heavy-oil-viscosity-reduction
#18
Chunwei Shi, Wei Yang, Jianbin Chen, Xiaoping Sun, Wenyi Chen, Huiyong An, Yili Duo, Mingyuan Pei
In the present study, heavy oil viscosity reduction in Daqing oil field was investigated by using an ultrasonic static mixer. The influence of the ultrasonic power on the viscosity reduction rate was investigated and the optimal technological conditions were determined for the ultrasonic treatment. The mechanism for ultrasonic viscosity reduction was analyzed. The flow characteristics of heavy oil in the mixer under the effect of cavitation were investigated using numerical modeling, and energy consumptions were calculated during the ultrasonic treatment and vis-breaking processes...
July 2017: Ultrasonics Sonochemistry
https://www.readbyqxmd.com/read/28426180/secondary-sensitivity-control-of-silver-nanowire-based-resistive-type-strain-sensors-by-geometric-modulation-of-the-elastomer-substrate
#19
Yunjeong Heo, Youngkyu Hwang, Hoon Sun Jung, Sung-Hoon Choa, Heung Cho Ko
A secondary method for modulation of the sensitivity in silver nanowire (AgNW) resistive-type strain sensors without the need to change the material or coating process in the sensory layer is demonstrated. Instead of using a planar elastomer (polydimethylsiloxane is used in this study) substrate, diverse relief structures are introduced to induce nonuniform and complex strain within the elastic substrate and thereby different distributions of the crack density of the AgNWs upon stretching, which plays an important role in the modulation of the gauge factor (GF)...
April 20, 2017: Small
https://www.readbyqxmd.com/read/28425466/crystal-structures-of-the-no-sensor-nsrr-reveal-how-its-iron-sulfur-cluster-modulates-dna-binding
#20
Anne Volbeda, Erin L Dodd, Claudine Darnault, Jason C Crack, Oriane Renoux, Matthew I Hutchings, Nick E Le Brun, Juan C Fontecilla-Camps
NsrR from Streptomyces coelicolor (Sc) regulates the expression of three genes through the progressive degradation of its [4Fe-4S] cluster on nitric oxide (NO) exposure. We report the 1.95 Å resolution crystal structure of dimeric holo-ScNsrR and show that the cluster is coordinated by the three invariant Cys residues from one monomer and, unexpectedly, Asp8 from the other. A cavity map suggests that NO displaces Asp8 as a cluster ligand and, while D8A and D8C variants remain NO sensitive, DNA binding is affected...
April 20, 2017: Nature Communications
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