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M B Agranat, O V Chefonov, A V Ovchinnikov, S I Ashitkov, V E Fortov, P S Kondratenko
We report on the experimental observation of high-power terahertz-radiation-induced damage in a thin aluminum film with a thickness less than a terahertz skin depth. Damage in a thin metal film produced by a single terahertz pulse is observed for the first time. The damage mechanism induced by a single terahertz pulse could be attributed to thermal expansion of the film causing debonding of the film from the substrate, film cracking, and ablation. The damage pattern induced by multiple terahertz pulses at fluences below the damage threshold is quite different from that observed in single-pulse experiments...
February 23, 2018: Physical Review Letters
Matthew J Catenacci, Christopher Reyes, Mutya A Cruz, Benjamin J Wiley
Materials that retain a high conductivity under strain are essential for wearable electronics. This article describes a conductive, stretchable composite consisting of a Cu-Ag core-shell nanowire felt infiltrated with a silicone elastomer. This composite exhibits a retention of conductivity under strain that is superior to any composite with a conductivity greater than 1000 S cm-1 . This work also shows how the mechanical properties, conductivity, and deformation mechanism of the composite changes as a function of the stiffness of the silicone matrix...
March 14, 2018: ACS Nano
A A Alhasyimi, P P Pudyani, W Asmara, I D Ana
OBJECTIVE: To evaluate the effect of carbonated hydroxyapatite-incorporated advanced platelet-rich fibrin on relapse and bone remodelling in rabbits. MATERIALS AND METHODS: Forty-five rabbits were divided into 3 groups (n = 15): a control group, carbonated hydroxyapatite (CHA) and carbonated hydroxyapatite-incorporated advanced platelet-rich fibrin (CHA-aPRF) group. The lower incisors were subjected to an orthodontic force of 50 cN. During the retention period, CHA and CHA-aPRF hydrogel were gently injected in the mesial gingival sulcus every 7 days...
March 14, 2018: Orthodontics & Craniofacial Research
Ruike Zhao, Shaoting Lin, Hyunwoo Yuk, Xuanhe Zhao
Structures of thin films bonded on substrates have been used in technologies as diverse as flexible electronics, soft robotics, bio-inspired adhesives, thermal-barrier coatings, medical bandages, wearable devices and living devices. The current paradigm for maintaining adhesion of films on substrates is to make the films thinner, and more compliant and adhesive, but these requirements can compromise the function or fabrication of film-substrate structures. For example, there are limits on how thin, compliant and adhesive epidermal electronic devices can be fabricated and still function reliably...
March 14, 2018: Soft Matter
K Kavvadia, K Seremidi, C Reppa, M Makou, P Lagouvardos
AIM: To clinically validate the fluorescence devices, DIAGNOdent Pen™ and Vista Proof™ for the evaluation of non-cavitated white spot lesions (WSL) in orthodontic patients and using direct visual examination after the brackets removal, as the gold standard. METHODS: The sample consisted of 31 patients, 13-28 years old, under fixed appliance orthodontic treatment. Teeth (N = 619) were evaluated with the brackets on, after cleaning and air drying, by direct, indirect visual examination and using the DIAGNOdent Pen™ device...
March 13, 2018: European Archives of Paediatric Dentistry: Official Journal of the European Academy of Paediatric Dentistry
Timotheus K T Wolterbeek, Amir Raoof
Defects along wellbore interfaces constitute potential pathways for CO2 to leak from geological storage systems. In previous experimental work, we demonstrated that CO2 -induced reaction over length-scales of several meters can lead to self-sealing of such defects. In the present work, we develop a reactive transport model that, on the one hand, enables μm-mm scale exploration of reactions along debonding defects and, on the other hand, allows simulation of the large, 6 m-long samples used in our experiments...
March 8, 2018: Environmental Science & Technology
C D Bergoli, L P Brondani, V F Wandscher, Gkr Pereira, M S Cenci, T Pereira-Cenci, L F Valandro
OBJECTIVES: The aim of this prospective randomized multicenter clinical trial was to evaluate the survival rate of glass fiber-reinforced posts cemented with self-adhesive or regular resin cements. METHODS: The sample was comprised of 152 teeth randomized within two centers and in accordance with the adhesive strategies for RelyX U100/U200 (3M ESPE) or Single Bond and RelyX ARC (3M ESPE). The cementation procedures were standardized and performed by previously trained operators...
March 2018: Operative Dentistry
Saman Faruqui, Mubassar Fida, Attiya Shaikh
BACKGROUND: One of the first concerns of new orthodontic patients, apart from the outcome, is the duration of treatment. A better understanding of orthodontic treatment duration as well as factors affecting the treatment duration is useful for efficient patient counselling and improved clinical practice. Hence, the objectives of this study are to compare the treatment durations of subjects with Class I and Class II division 1 (II/1) malocclusions, and to identify the factors affecting the treatment duration of these malocclusions...
January 2018: Journal of Ayub Medical College, Abbottabad: JAMC
Wadih Abou Hamdan, Sherine Badri, Ahmed El Sayed
AIM: The aim of this study was to evaluate in vitro the effectiveness of fluoride Vanish™ in preventing enamel demineralization around and under orthodontic brackets, using a laser fluorescence monitoring device on a group of teeth, using a laser fluorescence monitoring device on a group of extracted teeth with bonded brackets. METHODS: Orthodontic brackets were bonded to 32 extracted premolars. Buccal surfaces of teeth were divided into two halves: mesial and distal, fluoride Vanish™ (3M Unitek, Monrovia, CA, USA) was applied only on the distal half while the mesial one served as control half...
March 1, 2018: International Orthodontics
Vladimir A Inozemtsev, Artemii L Gamov, Alexander P Moscalets
In the present paper, adhesive properties (in terms of practical work of adhesion, Wa , and maximum stress in probe tack test) of blends of polyvinyl pyrrolidone (PVP) with polyethylene glycol (PEG-400) are studied at different level of stretching stress, applied perpendicular to the probe. The anisotropic behavior in both directions is investigated. Upon stretching, blends of 50/50 wt% PVP-PEG demonstrate little decrease in tack and little increase in maximum debonding stress. Whereas for more cohesive blends like PVP-PEG mixtures with down to 35 wt% of PEG, a significant reduction in Wa at the size of an order of a magnitude is observed...
March 1, 2018: Soft Matter
Irma Dumbryte, Jurate Vebriene, Laura Linkeviciene, Mangirdas Malinauskas
Objectives: To evaluate and compare the enamel microcracks (EMCs) characteristics (qualitative and quantitative) in the form of tooth damage before and after debonding from human teeth of in vitro studies. Eligibility criteria: Laboratorial studies evaluating EMCs characteristics before and after debonding metal and ceramic brackets from human teeth with intact buccal enamel. Information sources: An electronic search of four databases (all databases of the Cochrane Library, CA Web of Science, MEDLINE via PubMed, and Google Scholar) and additional manual searches were carried out, without language restrictions...
February 21, 2018: European Journal of Orthodontics
Eui-Hyun Kim, Hyunbae Lee, Jae-Hwan Kim, Seung-Muk Bae, Heesu Hwang, Heesun Yang, Eunsoo Choi, Jin-Ha Hwang
Self-healing is an essential property of smart concrete structures. In contrast to other structural metals, shape memory alloys (SMAs) offer two unique effects: shape memory effects, and superelastic effects. Composites composed of SMA wires and conventional cements can overcome the mechanical weaknesses associated with tensile fractures in conventional concretes. Under specialized environments, the material interface between the cementitious component and the SMA materials plays an important role in achieving the enhanced mechanical performance and robustness of the SMA/cement interface...
February 22, 2018: Materials
Francois De Luca, Giorgio Sernicola, Milo S P Shaffer, Alexander Bismarck
The fiber-matrix interface plays a critical role in determining composite mechanical properties. While a strong interface tends to provide high strength, a weak interface enables extensive debonding, leading to a high degree of energy absorption. Balancing these conflicting requirements by engineering composite interfaces to improve strength and toughness simultaneously still remains a great challenge. Here, a nanostructured fiber coating was realized to manifest the critical characteristics of natural nacre, at a reduced length scale, consistent with the surface curvature of fibers...
February 13, 2018: ACS Applied Materials & Interfaces
Takashi Hatayama, Ayaka Chiba, Kimisuke Kainose, Masatoshi Nakajima, Keiichi Hosaka, Noriyuki Wakabayashi, Richard M Foxton, Junji Tagami
This study aimed to evaluate influence of different post-end positions in alveolar bone level on stress distributions in resin-core build-up tooth under different load directions. Three-dimensional mathematical models of a root-filled mandibular premolar tooth were constructed. Resin post and core were built-up with six post lengths: 0, 1, 2, 3, 4, and 6 mm. Finite element analysis calculated stress distributions with oblique load of 400 N to buccal cusp 45 degree from buccal side or from lingual side. The 3 mm-post length (post-end position equal to cancellous bone level) caused highest equivalent stress of post-end compared with the shorter or longer post length...
February 8, 2018: Dental Materials Journal
R Pilo, M Folkman, A Arieli, S Levartovsky
The absolute marginal gap (AMG) precementation and postcementation and the retention of zirconia crowns cemented to standardized molar preparations (4×10) by self-adhesive resin cements (SARCs) were evaluated. The following SARCs were used: RelyX U-200 (RXU200; 3M ESPE, Seefeld, Germany), SmartCem 2 (SC2; Dentsply, Milford, DE, USA), and G-Cem Automix (GCA; GC, Alsip, IL, USA). The control adhesive resin cement was Panavia 21 (PAN; Kuraray Dental Co Ltd, Osaka, Japan). Twenty measuring locations at a constant interval along the margins were marked, and the AMG was measured by an image analysis system connected to a stereomicroscope (20×)...
February 2, 2018: Operative Dentistry
Didem Nalbantgil, Murat Tozlu, Mehmet Oguz Oztoprak
OBJECTIVE: This study was done to compare the intrapulpal temperature change generated by different energy levels of Er:YAG laser used during debonding of ceramic brackets and find the most suitable level for clinical use. MATERIAL AND METHODS: Eighty polycrystalline alumina brackets were bonded on bovine incisor teeth, which were randomly divided into 4 groups of 20. One group was assigned as control. In the study groups, after laser exposure with 2, 4, or 6 Watt energy levels, brackets were debonded using an Instron Universal Testing machine...
February 2, 2018: Photomedicine and Laser Surgery
Ne Myo Han, Zhenyu Wang, Xi Shen, Ying Wu, Xu Liu, Qingbin Zheng, Tae-Hyung Kim, Jinglei Yang, Jang-Kyo Kim
Unidirectional graphene aerogels (UGAs) with tunable densities, degrees of alignment and electrical conductivities are prepared by varying the average size of precursor graphene oxide (GO) sheets between 1.1 and 1596 µm2. The UGAs prepared using ultralarge GO (UL-UGA) outperform those made from small GO in these properties. The UL-UGA/epoxy composites prepared by infiltrating liquid epoxy resin into the porous UGA structure exhibit an excellent electrical conductivity of 0.135 S cm-1, along with an ultralow percolation threshold of 0...
February 1, 2018: ACS Applied Materials & Interfaces
Carrol Jin, Florence Bennani, Andrew Gray, Mauro Farella, Li Mei
Objective: Retainers play a critical role in the long-term success of orthodontic treatment. The aims of this study were to evaluate the survival time of different retainers and to investigate the potential predictors of the retainer failures. Material and methods: A total of 591 retainers from 309 patients (between 2003 and 2014) were included in the study, including Hawley retainers (n = 199), vacuum-formed retainers (n = 34), lingual fixed retainers (n = 278), and the COMBO (a combination of two different retainers in the same arch; n = 80)...
January 24, 2018: European Journal of Orthodontics
Giuliano Lazzaroni, Lorenzo Nardini
The aim of this paper is to study the quasistatic limit of a one-dimensional model of dynamic debonding. We start from a dynamic problem that strongly couples the wave equation in a time-dependent domain with Griffith's criterion for the evolution of the domain. Passing to the limit as inertia tends to zero, we find that the limit evolution satisfies a stability condition; however, the activation rule in Griffith's (quasistatic) criterion does not hold in general, thus the limit evolution is not rate-independent...
2018: Journal of Nonlinear Science
Celin Arce, Nathaniel C Lawson, Perng-Ru Liu, Chee Paul Lin, Daniel A Givan
PURPOSE: Screw-retained zirconia implant crowns with an internal titanium base have favorable mechanical properties compared with single-piece zirconia implant crowns; however, the screw-retained implant crowns require adequate bonding between the zirconia crown and the titanium base. This study measured the retention between a titanium base and a full-contour zirconia implant crown following different surface treatments of their bonded surfaces. MATERIALS AND METHODS: Full-contour screw-retained zirconia implant crowns were fabricated to fit a titanium base...
January 19, 2018: International Journal of Oral & Maxillofacial Implants
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